Abstract
Data Blitz Oral Presentations
SLEEP FRAGMENTATION FOLLOWING TRAUMATIC BRAIN INJURY EXACERBATES SUB‐ACUTE BEHAVIORAL DEFICITS AND TRANSCRIPTIONAL CHANGES AT CHRONIC TIME POINTS
1Department of Neuroscience, The Ohio State University, Columbus OH, United States, 2Institute for Behavioral Medicine Research, The Ohio State University, Columbus OH, United States, 3College of Medicine, University of Arizona, Phoenix AZ, United States, 4Department of Integrative Physiology, University of Colorado, Boulder, Boulder CO, United States
Stressful experiences elicit an immune response that is initially adaptive. However, persistent stress shifts the immune response to be detrimental. Stress‐immune interactions may worsen long‐term outcome in traumatic brain injury (TBI) survivors, who often experience impaired stress response. Here, we leverage sleep fragmentation (SF) as a common physiological consequence of stress to study post‐TBI neuroinflammation. We hypothesize that post‐injury SF exacerbates TBI‐induced sleep‐wake disturbances, neuroinflammation, and cognitive impairments. Adult male and female mice received either a moderate lateral fluid percussion TBI or a sham injury. Mice were exposed to SF 5am‐10am beginning one hour prior to light cycle or remained in control housing for 14 days post‐injury (DPI). At 14DPI all mice were allowed to recover until 30DPI. Sleep‐wake activity was acquired for all mice using custom piezo‐electric sensors for 30DPI.
TBI increased sleep for 4 hours following injury. Unexpectedly, all mice exposed to SF slept more than control mice through 7DPI. However, post‐TBI SF exacerbated spatial learning and memory deficits in the Morris water maze 14DPI. By the last week of recovery SF mice slept comparably to control animals. Nonetheless, post‐TBI SF increased transcription of cortical inflammation (Spi1, Abca1, Itga7), neurodegeneration (Abca1, Atg2b), and immunometabolic (Abca1, Lpl) genes compared to other groups. Canonical pathway analysis revealed that post‐TBI SF upregulated the complement cascade, and nitric oxide and reactive oxygen species production in macrophages. Together, these results indicate that post‐injury stress impairs the ability of the brain to adequately respond to and recover from injury.
Keywords: Sleep, Microglia, Cognition/Learning/Memory, Inflammation/Immune Function
SMOOTH MUSCLE EXCITATION AND REMODELING OF COLONIC INTERSTITIAL CELLS OF CAJAL AFTER SPINAL CORD INJURY
1Penn State University College of Medicine, Hershey PA, United States
Spinal cord injury (SCI) frequently provokes reduced colonic transit; termed neurogenic bowel. Intrinsic to the colon, the enteric nervous system (ENS) drives smooth muscle slow‐wave activity largely through Interstitial Cells of Cajal (ICC). These electrically coupled pacemaker cells generate electrical activity by phasic Ca2+ release and are further influenced by excitatory (ACh) and inhibitory (NO, ATP) neural inputs from the ENS. Neurogenic bowel treatment often involves pro‐motility drugs targeting the ENS and ICC's, which are often clinically ineffective.
This study aims to expand current understanding of neurogenic bowel neurobiology in acute and chronic SCI rats by accessing colonic ICC's plasticity and neuromuscular responsiveness to promotility drugs. Experimentally, male and female rats received surgical control or T3 SCI (n = 41). Following euthanasia, distal colon smooth muscle was harvested for immunohistochemical and electrophysiological analysis. The ICC's were fluorescently labeled with c‐Kit antibody. Upon quantification, we identified a significant increase in pacemaker myenteric plexus ICC's (p = 0.05) and their projection length (p = 0.009) following chronic SCI. Additionally, a significant interaction effect was observed between animal timepoint and surgical group for cell count (p = 0.001). Smooth muscle electrophysiology revealed that during application of cholinergic agonist (Bethanechol), cells depolarized in a dose dependent manner in control and SCI rats (p < 0.0001). Inversely, neuronally‐mediated colonic junction potentials did not respond upon electrical field stimulation in a dose dependent manner after SCI. The current data illustrates a potential compensatory ICC response due to loss of functional inputs, alluding to why pro‐motility ENS and ICC pharmacodynamics have poor patient satisfaction.
Support: NINDS‐105987
Keywords: Imaging, Electrophysiology
EPISODIC MEMORY IMPAIRMENT FOLLOWING MILD TRAUMATIC BRAIN INJURY
1Indiana University, Bloomington IN, United States
Mild traumatic brain injury (mTBI) is the most common type of traumatic brain injury, and it leads to temporary memory impairment as well as an excitotoxic response in the brain, particularly the hippocampus. While many animal models of mTBI exist, it is difficult to fully replicate the injury seen in humans, and the effects of mTBI on the microenvironments of the brain are unclear. Additionally, no treatments specifically for mTBI currently exist. Notably, the Wayne State modified weight drop rat model of mTBI accurately recapitulates the elements of a sport‐related injury, as well as the excitotoxic response in the hippocampus. Yet, this model has not previously been evaluated using a complex memory task. In this study, rats were trained in an odor‐based item‐in‐context task which dissociates episodic and non‐episodic memory (Panoz‐Brown et al., Current Biology, 2016). The animals then underwent either a weight drop or sham treatment using the Wayne State model. After the manipulation, animals continued the item‐in‐context task. Episodic memory suffered a 11% drop in performance (p < 0.01) in the injured rats, but not in the sham rats. Non‐episodic memory was not impaired in either group. Additionally, immunohistochemical analysis of the hippocampus documented morphological changes in astrocytes and microglia in injured rats compared to sham rats. These findings are the first to document episodic memory impairment in an animal model of mTBI.
Keywords: Astrocyte, Microglia, Cognition/Learning/Memory, Imaging, Concussion/mTBI, Inflammation/Immune Function
ASSESSMENT OF MAGNETIC RESONANCE IMAGING CHANGES IN RESPONSE TO DAILY GUT MICROBIAL THERAPY IN A PIGLET TBI MODEL
1Department of Animal and Dairy Science, University Of Georgia, Athens GA, United States, 2Neuroscience Program, Biomedical and Health Sciences Institute, University of Georgia, Athens GA, United States , 3Regenerative Bioscience Center, University of Georgia, Athens GA, United States , 4Department of Foods and Nutrition, College of Family and Consumer Sciences, University of Georgia, Athens GA, United States
Pediatric traumatic brain injury (TBI) is a leading cause of death and disability in children. Due to the bidirectional communication between the brain and gut microbial population, the introduction of key gut bacteria may mitigate critical TBI‐induced secondary injury cascades, thus lessening neural damage. The objective of this study was to determine the ability of gut microbial transplantation (GMT) to reduce injury severity in a piglet TBI model. A moderate/severe TBI was induced by controlled cortical impact in 4‐week‐old male crossbred piglets (treated: GMT, n = 6; control: CON, n = 6). Sham animals (S, n = 6) underwent craniectomy only. TBI animals were administered a 25 mL oral gavage of GMT or saline, 2‐hours post‐injury and every 24 hours for 7 days. An MRI was collected 1‐day (1D) and 7‐days (7D) post‐injury. Sequences included T2 FSE for lesion volume and midline shift (MLS) analysis, and SWAN for intracranial hemorrhage (ICH) volume measurement. No differences were noted between lesion volume, ICH volume, or MLS between GMT and CON pigs at 1D. GMT animals exhibited smaller lesion volumes (P = 0.005) and reduced ICH volumes (P = 0.031) at 7D relative to 1D. At 7D, MLS did not significantly differ between GMT and S animals. No significant differences were observed in lesion and ICH volume between 1D and 7D in CON animals. CON animals showed the most pronounced level of MLS at 7D, which differed from CON 1D (P = 0.004). These results indicate that daily GMT significantly decreased neural injury severity after a moderate/severe pediatric TBI.
Keywords: Pediatric, Secondary Injury, Imaging, Therapeutics/Drug Discovery
ENDOCANNABINOIDS 2‐ARACHIDONOYLGLYCEROL AS AN IMMUNE MODULATOR OF NEUROVASCULAR RECOVERY AFTER TRAUMATIC BRAIN INJURY
1Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta GA, United States, 2Department of Psychiatry and Behavioral Sciences at University of Washington, School of Medicine, Seattle WA, United States, 3Department of Oral Biology and Diagnostic Science, Dental College of Georgia, Augusta University, Augusta GA, United States, 4Department of Neurology, Medical College of Georgia, Augusta University, Augusta GA, United States
Inflammation is an important mediator of secondary pathological events after traumatic brain injury (TBI). Endocannabinoids, endogenously produced arachidonate based lipids, are endogenous anti‐inflammatory compounds and bind to two cannabinoid receptors‐CB1R and CB2R, yet the molecular and cellular mechanisms underlying these effects are poorly defined. In the present study, we hypothesize that TBI‐induced loss of endocannabinoids exaggerate neurovascular injury and cause behavioral dysfunction. We determined the human CSF and plasma levels of endocannabinoids post‐TBI and correlated with a murine controlled cortical impact (CCI) model of TBI. Briefly, adult mixed sex C57Bl/6j or CD1 mice were anesthetized, placed in a stereotaxic frame, and a craniotomy was made in the right parietal bone, leaving the dura intact. Mice were impacted at 3 m/s with a 85 ms dwell time and 3 mm depression using a 3 mm diameter convex tip to mimic a moderate TBI. Sham‐operated control mice underwent the identical surgical procedures, but were not impacted. We observed acute loss of cerebral blood flow (CBF) with upregulated glial fibrillary acidic protein (GFAP), ionized calcium binding adaptor molecule 1 (IBA1) and aquaporin 4 (AQP4) up to 3 weeks with severe inflammation after TBI. Attenuated CBF resulted in loss of motor functions and induced anxiety behavior in TBI mice. However, inhibition of endocannabinoid 2‐arachidonyl glycerol (2‐AG) metabolism or supplementation of exogenous 2‐AG protected the blood flow, minimized inflammation, and reduced edema after injury. Taken together, our findings suggest an important modulatory role of 2‐AG and its metabolism in neurovascular injury and long‐term functional deficits.
Keywords: Secondary Injury, Vascular, Inflammation/Immune Function, Neuropathology
AMPLIFIED GLIOSIS AND INTERFERON‐ASSOCIATED INFLAMMATION IN AGED MICE FOLLOWING TRAUMATIC BRAIN INJURY
1The Ohio State University, Columbus OH, United States
Traumatic brain injury (TBI) is associated with an increased risk of cognitive and neurodegenerative complications that may develop and persist years after injury. Aged individuals are particularly susceptible to fall‐related TBIs and account for the most TBI‐related hospitalizations and deaths. We have shown that diffuse brain injury causes prolonged neuroinflammation associated with a pronounced increase in type 1 IFN signaling. Here, we compared the neuroinflammatory response to diffuse TBI between adult and aged mice. Adult (2 mo) and aged (16‐18 mo) C57BL/6 mice were subjected to a diffuse brain injury, induced by midline fluid percussion, after which several biochemical and behavioral parameters were assessed 7 days post injury (dpi). As expected, acute cognitive impairment was evident 7 dpi in both adult and aged TBI mice. There was enhanced reactive gliosis 7 dpi (IBA1, microglia and GFAP, astrocytes) in the cortex and hippocampus of aged mice. Neuropathology RNA analysis showed amplified cytokine/chemokine, complement, inflammatory, and interferon‐associated gene expression in the cortex of aged mice after TBI compared to adults. Ingenuity Pathway Analysis confirmed interferon (IFN) signaling was robustly enhanced in Aged‐TBI. Accordingly, we used a STING (stimulator of interferons) agonist, to determine if enhanced IFN signaling would worsen neuroinflammation after TBI in adult mice. There was a significant interaction between DMXAA and TBI. Adult TBI mice treated with the STING agonist had amplified expression of myriad genes that were also amplified in aged TBI mice. Overall, persistent IFN‐associated inflammation induced by TBI was especially prominent in aged mice.
Keywords: Secondary Injury, Microglia, Aging, Inflammation/Immune Function
TRANSFORMING RESEARCH AND CLINICAL KNOWLEDGE IN GERIATRIC TBI (TRACK‐GERI): INITIAL ENROLLMENT AND OUTCOMES
1University Of California San Francisco, San Francisco CA, United States, 2University of Pittsburgh Medical Center, Pittsburgh PA, United States, 3University of Washington, Seattle WA, United States, 4MedRhythms, Portland OR, United States
Keywords: Cognition/Learning/Memory, Aging, Neurodegeneration, Concussion/mTBI
CNR2 IS UPREGULATED ON THE CEREBROVASCULATURE FOLLOWING EXPERIMENTAL TRAUMATIC BRAIN INJURY INDICATING THE POTENTIAL FOR CANNABINOID RECEPTOR 2 AS A DRUGGABLE INTERVENTION STRATEGY
1Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia PA, United States, 2Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia PA, United States, 3Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, Philadelphia PA, United States, 4Instituto de Quíca Médica, Consejo Superior de Investigaciones Científicas, Madrid, Spain
Traumatic brain injury is a substantial public health issue for which there are no currently approved pharmacological interventions. Previous research shows Cannabinoid Receptor 2 (CB2) agonists promote resolution of inflammation in multiple neuroinflammatory disease states. Here, we hypothesized CB2 is a potential pharmacological target at the level of the cerebral vasculature following experimental TBI. First, C57BL/6 mice (n = 3/group) were given a moderate TBI (CCI, 4.5m/s, 2mm impact depth) and CNR2, the gene encoding for CB2, expression was analyzed via qRT‐PCR at 4, 8, 24, and 48 hours post injury. Results indicated a 20‐fold upregulation of CNR2 (p < 0.0001) in mouse microvessels isolated from the area of impact 24 hours after injury. To subsequently evaluate the translational aspects of targeting CB2 on the cerebral endothelium, we treated human brain microvascular endothelial cells with TNFα and a novel CB2 agonist, PM289 (n = 3/experiment). PM289 is a novel chromenopyrazole derivative featuring enhanced solubility and specificity for CB2. Utilizing an in vitro blood brain barrier model (BBB), we analyzed the effects of PM289 on the integrity of the BBB using Electrical Cell‐Substrate Impedance Sensing and Western Blot. These experiments demonstrated that PM289 significantly reduced TNFα induced disruptions to the physical barrier (p < 0.05). Moreover, PM289 attenuated TNFα‐induced endothelial activation (p < 0.05). Taken together, these results show that CB2 is a viable treatment target at the level of the cerebral vasculature following experimental neurotrauma. Ongoing studies are aimed at interrogating the intracellular signaling events responsible for these cerebrovascular protective effects.
Keywords: Secondary Injury, Blood Brain Barrier, Vascular, Inflammation/Immune Function
WHETHER NOREPINEPHRINE TREATMENT AFTER SPINAL CORD INJURY INDUCES HEMORRHAGE DEPENDS UPON TIME OF ADMINISTRATION AND SEX
1Department of Psychological & Brain Sciences, Texas A&M University, College Station TX, United States, 2Texas A&M Institute for Neuroscience, College Station, Unites States, 3Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, Canada
Our prior work focused on how pain after spinal cord injury (SCI) undermines locomotor recovery, and provides evidence pain increases the area of hemorrhage. We hypothesized that pain may be having this effect because it drives an acute rise in systolic blood pressure. The current study explores this issue by pharmacologically inducing hypertension with norepinephrine (NE). In all experiments, Sprague‐Dawley rats received a contusion injury at the T10‐T11 spinal level. Baseline BBB and/or tail blood pressure (BP) were assessed prior to treatment. In experiment 1, male rats received NE or vehicle 30 min or 24 hrs post‐SCI to assess the window of time in which the spinal cord is most vulnerable to hypertension. In experiment 2, male rats received NE or vehicle at the beginning of treatment and then again 1.5 hr later to examine the effects of maintained hypertension. In experiment 3, male and female rats received NE or vehicle 24‐hrs post‐SCI to assess for sex‐differences. BP and/or BBB scores were assessed 0, 1, 2, and 3 hours after treatment. Tissue was then collected and assessed for hemorrhage using spectrophotometry in experiments 1 & 2, and histology in experiment 3. NE produced an increase in BP and hemorrhage and the magnitude of these effects varied with time post‐SCI. NE also, undermines locomotor recovery when given 24 hrs post‐SCI in both males and females. Additional studies are being conducted to assess the mechanism by which NE is acting.
Keywords: Behavioral Function, Secondary Injury, Neurotoxicity, Hemorrhage
AGE‐ AND AGING‐WITH‐INJURY‐RELATED TEMPORAL MICROGLIAL MORPHOLOGICAL PROFILES INDICATE UNIQUE PATHOLOGICAL PROCESSES IN BEHAVIORALLY RELEVANT CIRCUIT RELAYS
1College of Medicine‐Phoenix, University of Arizona, Department of Child Health, Phoenix AZ, USA, 2BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix AZ, USA, 3Phoenix VA Healthcare System, Phoenix AZ, USA, 4University of Arizona, Tucson AZ, USA, 5Arizona State University, Tempe AZ, USA
Traumatic brain injury(TBI)‐induced chronic neuroinflammation is implicated in the development of persisting neurological morbidities and age‐related neurodegenerative diseases. A chronic time course of neuroinflammation in a behaviorally relevant circuit in both sexes is needed to accurately and comprehensively assess the benefits and consequences of neuroinflammation. We used a temporal profile for structural, molecular, and functional mechanisms contributing to late‐onset persisting sensory hypersensitivity in the rat whisker‐barrel‐circuit (WBC) relays to assess neuroinflammation. Age‐matched male and female Sprague‐Dawley rats underwent midline fluid percussion injury (FPI) or sham surgery (n = 5‐6/group;total = 64). At 7‐, 56‐, and 168‐days post‐injury (DPI), Iba‐1 stained morphologies and morphological characteristics were quantified in cortical and thalamic WBC relays followed by three‐way ANOVAs (FPI, DPI, Sex). In the cortex and thalamus, microglia had shorter branches and fewer endpoints, indicative of microglial activation, as a function of FPI (p < 0.05), DPI (p < 0.05), and FPI ͯ DPI (p < 0.05), where FPI‐induced activation decreased and age‐related activation (shams) increased over time. By 168DPI, sham and FPI morphological characteristics were similar; However, hyper‐ramified microglia increased in sham versus FPI (p < 0.05). Cortical rod microglia were highest at 7DPI (p < 0.05) and present through 168DPI (FPI ͯ DPI interaction; p < 0.05). FPI ͯ DPI ͯ Sex interaction for thalamic cell counts (p < 0.05) indicated a greater FPI response in 7DPI males versus females (p < 0.05). Chronic TBI‐induced neuroinflammation has a distinct regional and sex‐dependent temporal profile compared to age‐related neuroinflammation, providing a template for more comprehensive interpretation of the impact of intervention on specific pathological processes associated with aging‐ and aging‐with‐injury‐related morbidities.
Keywords: Microglia, Aging, Neurodegeneration, Neuropathology
NTS‐105 DECREASES CELL DEATH AFTER IN VITRO STRETCH INJURY
1Department of Biomedical Engineering, Columbia University, United States
Administration of pleiotropic neurosteroids have demonstrated neuroprotective potential in experimental models of traumatic brain injury (TBI). NTS‐105 is a novel neurosteroid with demonstrated activity at multiple intracellular nuclear hormone receptor systems known to protect brain tissue after acute injury. To evaluate the potential for NTS‐105 to reduce cell death in an organotypic hippocampal slice culture (OHSC) stretch injury model of moderate‐severe TBI, P8‐10 Sprague Dawley hippocampi were sliced into 400 μm sections and cultured on PDMS wells. Propidium iodide (PI) staining was performed to confirm less than 5% cell death in OHSCs at least 10 days after culture. Healthy slices were stretched to an average equibiaxial strain of 26% at 9.8 1/s. One hour after injury, cultures were treated with NTS‐105, progesterone (1 nM as positive control) or vehicle. At 96 hours after injury cell death was quantified. Over a broad concentration range, NTS‐105 significantly reduced neuronal cell death compared to vehicle. The decrease in cell death over that range was similar to 1 nM progesterone (1.18 ± 0.44%; N = 13; p < 0.05 vs vehicle). The dose‐response of NTS‐105 indicated that prevention of cell death was lost at high exposure levels (i.e. neuroprotection observed with NTS‐105 concentrations as low as 0.1 nM (2.53 ± 0.77%; N = 20) but not at a high concentration of 300 nM (6.95 ± 3.13%; N = 16)). Thus, NTS‐105 produces significant stretch‐injured hippocampal neuroprotection over a broad concentration range and may be therapeutically beneficial for the treatment of TBI.
This study was supported by NeuroTrauma Sciences.
Keywords: Neuroprotection, Cell Death, Therapeutics/Drug Discovery, Biomechanics
FIBRILLIN‐1 MUTATION ACCELERATES CEREBROVASCULAR AGING AND INCREASES NEUROVASCULAR VULNERABILITY TO MILD TRAUMATIC BRAIN INJURY
1University of Arizona College of Medicine‐Phoenix, Phoenix AZ, United States, 2Midwestern University, Glendale AZ, United States, 3Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix AZ, United States, 4University of Colorado Boulder, Boulder CO, United States
Age presents a significant risk for prolonged morbidity and mortality after traumatic brain injury (TBI), yet mechanisms associated with age‐related cerebrovascular vulnerability following TBI remain unclear. Age‐induced transforming growth factor‐β (TGF‐β) upregulation is implicated in cerebrovascular dysfunction, loss of blood‐brain barrier (BBB) integrity, and increased risk of neuroinflammation and cognitive impairment. Fibrillin‐1 (Fbn1) mutation increases TGF‐β availability and signaling in Fbn1+/‐ mice, inducing peripheral vascular dysfunction by 6‐months of age. This study investigated Fbn1 deficiency on cerebrovascular integrity and increased vulnerability to TBI using a transgenic mouse model with constitutively increased TGF‐β conditions. We hypothesize that during conditions of increased TGF‐β availability, cerebrovascular aging accelerates, leaving the brain vulnerable to mild‐TBI (mTBI). In male and female 6‐ and 12‐month‐old Fbn1+/‐ and C57BL/6 wildtype (WT) mice (n = 3‐11/group), posterior cerebral artery (PCA) blood flow, PCA rupture point, BBB permeability, injury viability, neurological severity scale (NSS) outcomes, and microglial perturbation were assessed. We observed that 6‐month‐old Fbn1+/‐ mice exhibited significantly decreased PCA blood flow and wall strength (p < 0.05), exacerbated BBB permeability (p < 0.05), microglial activation (p < 0.05), and NSS scores (p < 0.05) compared to age‐matched WT mice that were comparable to 12‐month‐old WT mice. Fbn1+/‐ mice required a 15% lower pressure to induce mTBI righting reflex times (5‐10 minutes) compared to WT (p < 0.05), and sex differences were observed. At 24h post‐TBI, Fbn1+/‐ mice demonstrated increased BBB permeability and microglial activation. These findings indicate that Fbn1 mutation alters cerebrovascular vulnerability following mTBI, where age‐related modulation could be neuroprotective, and sex could be a determinant. Funding‐Valley_Research_Partnership‐P1A‐5012, NIH‐R15HL145646, NIH‐R01NS100793
Keywords: Aging, Blood Brain Barrier, Vascular, Cerebral Blood Flow
SEDATION TOXICITY IN PEDIATRIC TRAUMATIC BRAIN INJURY
1Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore MD, United States, 2Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore MD, United States, 3Department of Neurology and Neurosurgery, Johns Hopkins University School of Medicine, Baltimore MD, United States
Following severe pediatric TBI, patients commonly receive IV sedatives. Studies have shown negative effects of sedative exposure on the normal, developing brain. We hypothesized that early exposure to sustained sedation would worsen outcomes after TBI in immature rats. Male Sprague‐Dawley rats (PND 17) were divided into four groups: naive, naive‐sedation, TBI and TBI‐sedation. TBI groups underwent controlled cortical impact (CCI). Starting on post‐injury day (PID) 1, sedation groups received midazolam 12 h/day for 3 days. Histologic endpoints (PID 4) included Iba‐1, GFAP, TUNEL, Caspase‐8, and tissue loss. Separate groups of rats were used for mitochondrial measurements (PID 4) and long‐term behavior (PND 80‐120). TBI‐sedation rats had a decrease in Iba‐1 staining in the thalamus (Tukey's HSD, p < 0.05 vs TBI), and a decrease in Caspase‐8 in the dentate gyrus and cortex (unpaired t‐test, p < 0.05). TBI resulted in ∼7% ipsilateral tissue loss, with no difference between groups. In naive rats, 72 hours of sedation tended to reduce Iba‐1 staining across brain areas. TBI‐sedation rats had a lower mitochondrial respiratory control ratio than TBI alone. Behavioral analysis revealed a higher failure rate in a visual discrimination touchscreen task for TBI‐sedation rats. They also committed more errors and required more correction trials. In open‐field testing, TBI‐sedation rats spent significantly less time in the center of the field, and had more deficits on gait analysis than TBI rats. In summary, rats with post‐TBI sedation had reduced microglial staining and apoptotic activity early after injury, but had long‐term cognitive deficits in associative learning, locomotion and gait.
Keywords: Pediatric, Behavioral Function, Inflammation/Immune Function
EFFECTS OF CAFFEINE ON VESTIBULAR‐OCULAR MOTOR FUNCTION AND OBJECTIVE MEASURES OF CLINICAL OUTCOME AND RECOVERY FOLLOWING CONCUSSION IN ADOLESCENTS
1University Of South Carolina, Columbia SC, United States, 2Department of Pediatrics, Prisma Health Children's Hospital, Columbia SC, United States
Caffeine consumption is becoming increasingly prevalent within the adolescent population and often coincides with recreational activities where incidence of concussion is high. However, the influence of caffeine on concussion pathology is not well established. Therefore, the purpose of the present study was to determine if caffeine impacts clinical outcome and recovery in adolescents following concussion. Twenty‐four concussed adolescents who habitually consume caffeine (CAF+; 12 males, 12 females; 15 ± 1 years) and twelve matched non‐consumers (CAF‐) were clinically evaluated at a local pediatric concussion clinic on days 13 ± 7 (Eval1) and 32 ± 11 (Eval2) post injury. Working memory, executive function and visual memory recall were assessed using one (ONB) and two‐back (TWOB) tasks, the Groton maze learning task (GMLT), and the Groton maze delayed recall task (GMR), respectively. Cardio‐autonomic function was assessed via Heart rate variability (HRV), and the Vestibular Ocular Motor Screening (VOMS) was used to assess vestibular‐ocular motor function. Group main effects irrespective of time revealed CAF+ had significantly worse accuracy than CAF‐ for ONB task performance (P = 0.037) and a group X time interaction showed CAF+ had significantly worse TWOB performance accuracy than CAF‐ at Eval1 (P = 0.004). In addition, at both time points CAF+ had a suppressed HRV indexed via a lower SDNN (P = 0.046). However, CAF+ experienced fewer symptoms of fogginess during the VOMS compared to CAF‐ (P = 0.02). These findings suggest caffeine consumption can negatively impact cardio‐autonomic function and working memory in adolescents following concussion but may aid other cognitive domains by alleviating symptoms of mental fogginess.
Keywords: Pediatric, Executive Function, Concussion/mTBI, Electrophysiology
GLUTAMATERGIC HYPEREXCITABILITY IN HIPPOCAMPAL NEURONS INDUCED BY LOW‐INTENSITY BLAST EXPOSURE IS CONTRIBUTIVE TO LONG‐TERM LEARNING DEFICITS AND ANXIETY‐LIKE RESPONSES IN MICE
1Department of Pathology & Anatomical Sciences, University of Missouri School of Medicine, Columbia MO, United States, 2Truman VA Hospital Research Service, Columbia SC, United States, 3Department of Medicine, University of Missouri School of Medicine, Columbia SC, United States, 4Charles W. Gehrke Proteomics Center, University of Missouri, Columbia SC, United States, 5Department of Mining and Explosives Engineering, Missouri University of Science and Technology, Rolla MO, United States, 6Office of Research and Development, Department of Veterans Affairs, Washington DC, United States, 7Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda MD, United States
Cognitive and neuropsychological consequences of blast‐induced traumatic brain injury (bTBI) pose significant health concerns for military service members and veterans. However, underlying mechanisms of mild bTBI by low‐intensity blast (LIB) exposure resulting in long‐term cognitive and mental deficits remain elusive. Our prior studies using an open‐field blast model (350‐gram high‐energy C4) in mice in the absence of head motion revealed behavioral and ultrastructural impairments up to 1‐month post‐LIB injury. Recently, we found LIB‐induced hippocampal hyperexcitability linking to long‐term neurobehavioral impairments. In brain slice recordings, there was an increase in averaged frequencies with a burst pattern of miniature excitatory postsynaptic currents (mEPSCs) in hippocampal CA3 neurons in LIB‐exposed mice at 1‐ and 7‐days post‐injury, which was blocked by a specific NMDA receptor antagonist AP5 (Chen et al., in press). Label‐free quantitative proteomics using high‐throughput, tandem mass spectrometry with bioinformatic analysis showed altered expression of proteins involved in synaptic plasticity in hippocampal tissues 3‐months post‐LIB injury. Long‐term behavioral changes on cognition and learning were assessed at 3‐months post‐LIB using an automated home‐cage monitoring (HCM) system to minimize operator bias and interference. Changes were observed in multi‐domain responses of anxiety‐like behaviors in LIB‐exposed mice, including altered HCM sheltering behavior in a natural environment and increased kinematics when introduced to a challenged environment with an aversive light stimulus. Our results suggest that the LIB model with home‐cage behavioral assessment is a useful platform to develop clinical treatment, and support a more comprehensive neuropsychological testing and long‐term assessment of war‐fighters and veterans with bTBI.
Keywords: Behavioral Function, Blast, Concussion/mTBI, Synaptic Function
BALLISTIC MODELS OF BLUNT INJURY IN THE GYRENCEPHALIC BRAIN (SWINE): AXONAL PATHOLOGY IN THE BRAIN STEM
1Johns Hopkins School Of Medicine, Depart of Pathology, Baltimore MD, United States, 2Army DEVCOM Chemical Biological Center, Gunpowder MD, United States, 3Army SURVICE Engineering Company, Belcamp MD, United States, 4DEVCON Army Research Laboratory, APG, United States, 5Uniformed Services University, Bethesda MD, United States
The neuropathology of TBI when high‐velocity objects (bullets) strike the helmeted head (Behind‐Helmet Blunt Trauma‐BHBT) is an important problem for the military and beyond. We have shown before that BHBT is associated with subarachnoid hemorrhage (SAH) and diffuse vascular and axonal lesions. Axonal pathologies appear as classic diffuse axonal injury (DAI), which are indistinguishable from ones encountered in acceleration injuries. This finding suggests acute morbidity/mortality in BHBT may result from a combination of increased intracranial pressure and shearing. Here, we extend our previous findings to 42 brains of Yucatan swine injured from ballistic impacts to helmeted heads. Animals with stable or critical vitals were euthanized at 4 hours or immediately after injury, respectively. Paraffin serial sections were processed for anatomy (Nissl), vascular pathology (Masson's trichrome), and axonal pathology (APP). To explore acute mortality causes, we focused on brainstem DAI and microhemorrhages. Brain stems were divided into 92 regions: 48 representing gray matter, 29 white matter, and 15 regions of nerve tracts or yet undefined. Individual cases were taken for stereological analysis of DAI per region. The majority of cases had SAH. DAI in the brain stem differed among regions, but some areas such as the cerebral peduncle, substantia nigra‐pars reticulata, and certain thalamic regions were most heavily affected. There was common involvement of various subdivisions of the reticular formation. We observed correlation between regional DAI severity and neurological outcome, i.e. critical versus stable vital status post‐injury. We are still exploring relationships between DAI, microhemorrhages and post‐injury vital sign status.
Keywords: Neurodegeneration, Ballistic Injury, Axonal Injury, Hemorrhage, Vascular, Intracranial Pressure, Neurocritical Care, Neuropathology, White Matter
MONOCYTE DEPLETION ALTERS THE BRAIN INJURY‐INDUCED PHENOTYPIC SHIFT OF CIRCULATING AND INFILTRATING INNATE IMMUNE CELLS
1Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg VA, United States, 2Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke VA, United States, 3Center for Engineered Health, Virginia Tech, Blacksburg VA, United States
Monocyte/macrophages represent key cellular elements that contribute to tissue damage in the brain. Strategies aimed at their sequestration have revealed critical insight into the injury response that warrants further investigation. We show that suppressing circulating blood monocytes prior to murine brain injury, using clodronate encapsulated liposomes, augments the release of Ly6Chi monocytes that are swiftly skewed to LyC6‐/lo. We reveal this shift surprisingly results in reduced numbers of neutrophils and increased monocytes in the brain, with a predominate influx of Ly6Clow/‐ anti‐inflammatory monocyte/macrophages which correlates with neuroprotection. Moreover, the morphology of monocytes present in clodronate‐treated injured mice, designates them as a subset that are larger in size and granularity which implies their origin or maturation status are divergent from those released due to brain injury alone. Depleted mice reconstituted with immature monocytes isolated directly from the bone marrow (BM) retained protection from brain injury compared to those that were first allowed to mature ex vivo suggesting BM release of an alternate or immature monocyte subset may help curb tissue damage in the brain. Findings from this study suggest monocyte subsets and their maturation stage represents a unique cellular niche that may quell the neuroimmune response to brain injury
Keywords: Neuroprotection, Secondary Injury, Gene Expression, Inflammation/Immune Function
THE EFFECT OF SECRETED FRIZZLED RELATED‐PROTEIN 3 (SFRP3) AND WNT SIGNALING ON COGNITIVE BEHAVIOR AFTER TRAUMATIC BRAIN INJURY
1Johns Hopkins University School Of Medicine, Baltimore MD, United States
Traumatic brain injury (TBI) is a major cause of death and disability, with an incidence of approximately 64‐74 million cases occurring worldwide each year. An important avenue of research in TBI has been the use of stem cells for repair after injury. Wnt signaling modulates diverse cellular processes, including stem cell proliferation, differentiation, regeneration, and inflammation, through the canonical Wnt/β‐catenin and the noncanonical Wnt/calcium pathways. Recent studies have revealed that inhibition of the secreted Frizzled Related‐Protein 3 (sFRP3), an inhibitor of Wnt signaling, regulated neural stem cell quiescence and increased activity‐dependent proliferation and maturation in the hippocampus. Nevertheless, the role of sFRP3/Wnt in neurogenesis after brain injury remains unclear. Here, we examine the effect of sFRP3 deletion on neurogenesis in the subgranular and subventricular zones after TBI. We assess whether sFRP3 depletion promotes functional recovery four weeks after TBI. We used 10‐12 weeks old male C57BL/6 and homozygous sFRP3 knockout mice. The mice were randomly assigned to three groups: TBI, sham (craniotomy), and naïve. TBI was induced by controlled cortical impact (1.0 mm depth, 3.0 m/s at 15° impact angle). TBI causes a significant increase in righting reflex and modified neurological severity score. sFRP3 depletion improves the neurobehavioral outcome of learning and memory assessed by novel object recognition 4 weeks after TBI. Immunohistochemical analysis is currently underway to quantify the effects of sFRP3 inhibition on neurogenesis after TBI, assessing survival, differentiation, and maturation, in correlation with the described functional effects.
This work was supported by NIH grant R01NS105894.
Keywords: Behavioral Function, Cognition/Learning/Memory, Stem Cells, Neurogenesis
CARVACROL DECREASES THE BLOOD–BRAIN BARRIER PERMEABILITY AFTER DIFFUSE TRAUMATIC BRAIN INJURY IN RATS
1Endocrinology And Metabolism Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman, Iran (Islamic Republic of), 2American University of Beirut, Lebanon, 3College of Medicine‐Phoenix, University of Arizona, Phoenix AZ, USA
Previously, we showed that CAR, the active ingredient in Satureja Khuzestanica Jamzad essential oil (SKEO), 5‐isopropyl‐2‐methylphenol, has anti‐inflammatory, anti‐apoptotic, and anti‐edematous properties after experimental traumatic brain injury (TBI) in rats. In this study, the efficacy of CAR to protect the injured blood–brain barrier (BBB) was evaluated. Seventy‐two male Wistar rats were randomly divided into Five groups and injured using Marmarou weight drop: Sham, TBI, TBI+Vehicle, TBI+CAR (100 and 200 mg/kg) (we used n = 11/ cohort where n = 6 for water content and evans blue (EB) extravasation assay; n = 4 for ELISA and western blotting). Thirty minutes after TBI induction, vehicle and CAR were intraperitoneally injected. At 24h post‐injury, brain edema, BBB permeability, and BBB‐related protein levels (occludin, ZO‐1, and matrix metalloproteinase‐9; MMP‐9), and oxidative activity (malondialdehyde; MDA, superoxide production, superoxide dismutase activity; SOD, total antioxidative capability levels ;T‐AOC, and reactive oxygen species ;ROS) were measured. Our data showed that the CAR200 treatment decreased brain edema and ameliorated BBB permeability (P < 0.001). In addition, the CAR treatment suppressed the expression of MMP‐9 (P < 0.001), and increased expression of ZO‐1 and occluding (P < 0.01& P < 0.05 respectively). CAR also exerts antioxidant activity by inhibiting MDA and ROS (P < 0.05 & P < 0.001respectively), and increasing SOD and T‐AOC (P < 0.01). Taken together, these results indicated that CAR treatment showed BBB protection post TBI and offered a more affordable alternative as a treatment can prevent or attenuate post‐TBI symptoms by repairing some of TBI major pathological effects.
Keywords: Blood Brain Barrier
TOLL‐LIKE RECEPTOR‐4 DEPENDENT INCREASE IN MATRIX METALLOPROTEINASE‐9 UNDERLIES ALTERED NETWORK EXCITABILITY AND PLASTICITY IN HIPPOCAMPAL DENTATE GYRUS IN RODENT MODEL OF TRAUMATIC BRAIN INJURY
1University Of California ‐ Riverside, Riverside CA, United States
Early inflammatory responses are known to drive epileptogenesis and memory deficits following Traumatic Brain Injury (TBI). We recently identified that Toll‐like receptor 4 (TLR4), an innate immune receptor could be targeted to limit epileptogenesis and memory deficits after TBI by mechanisms which are not fully understood. Here we examined whether TLR4 signaling recruits Matrix Metalloproteinase‐9 (MMP‐9), a potent Zn+ activated endopeptidase, and if the TLR4:MMP‐9 signaling axis alters neuronal excitability and synaptic plasticity in the hippocampal dentate gyrus (DG) after concussive brain injury. Rats (p24) subjected to moderate lateral Fluid Percussion Injury (l‐FPI)/ sham injury were treated with antagonists of TLR4 (CLI‐095, 0.5mg/kg,i.p.) or MMP‐9 (SB‐3CT, 50mg/kg,i.p.) or vehicle 30min to 24hrs post‐injury and examined at 48 hrs for MMP‐9 activity and at one week for changes in DG excitability. In situ zymography revealed an increase in MMP‐9 activity 48 hrs after l‐FPI, which was reduced by CLI‐095 treatment (n = 4/group). In urethane anesthetized rats, responses to activation of perforant path inputs to DG in vivo revealed an increase in excitability and impaired long‐term potentiation one week after l‐FPI, which were reduced by treatment with CLI‐095 or SB‐3CT (n = 3‐4/group). Together, our results provide the first evidence of TLR4 mediated increase in MMP‐9 activity after TBI and identify a role for TLR4:MMP‐9 signaling in altered dentate excitability and plasticity following TBI.
Keywords: Cognition/Learning/Memory, Epilepsy/Seizure, Electrophysiology, Inflammation/Immune Function
Data Blitz Oral Presentations & Poster Competition Finalists
SEX DIFFERENCES IN ALTERED FUNCTIONAL ACTIVITY OF OREXIN NEURONS AFTER MILD TRAUMATIC BRAIN INJURY
Mrs. Rebecca Somach1,2, Mr. Ian Jean2, Dr. Akiva Cohen1,2
1University Of Pennsylvania, Philadelphia PA, United States, 2Children's Hospital of Philadelphia, Philadelphia PA, United States
Sleep disorders are a common occurrence after mild traumatic brain injury (mTBI) with 30‐70% of patients reporting a sleep disorder after injury. Furthermore, women are more susceptible to sleep disorders in the general population, signaling that disruptions to sleep can be affected by sex. Little work has been done to understand functional changes in sleep circuitry after mTBI, and even less has been done to study if injury induced alterations to sleep circuitry would differ by sex. Previous work from our lab has demonstrated that animals display an inability to maintain wakefulness after injury. Therefore, this study examines a specific cell type, orexin neurons, that normally promote arousal and wakefulness. We studied orexin neurons in male and female mice 6‐8 weeks of age one week after a lateral fluid percussion injury (LFPI) [N = Between 4‐10 animals per group]. We used the whole cell patch clamp technique to record functional properties from orexin neurons. In male mice, we found that there was a decrease in the amplitude and frequency of excitatory afferent synaptic activity onto orexin neurons [P < 0.0001 with a Kolmogorov‐Smirnov test]. Interestingly in females we found reduced afferent excitatory activity together with an increase in afferent inhibitory activity that was not present in male animals. These changes in afferent synaptic activity would all lead to reduced activity in orexin neurons but do so through different mechanisms. This indicates that sex differences are important to consider when studying the circuit based mechanisms of the symptoms of mTBI.
Keywords: Sleep, Concussion/mTBI, Synaptic Function, Electrophysiology
INHIBITION OF AUTOPHAGY IN MICROGLIA AND INFILTRATING MONOCYTES/MACROPHAGES EXACERBATES NEUROINFLAMMATION AND FUNCTIONAL DEFECTS FOLLOWING TRAUMATIC BRAIN INJURY
1University Of Maryland, Baltimore, Baltimore MD, United States
The autophagy‐lysosomal pathway serves an important role in cellular homeostasis and protection against neurodegeneration. Recently autophagy has been also implicated in regulation of immune and inflammatory responses: high levels of autophagy flux are generally associated with anti‐inflammatory responses, and inhibition of flux with pro‐inflammatory responses.
To determine if autophagy may be involved in modulation of brain inflammation after traumatic brain injury (TBI), we assessed the levels of autophagy in resident microglia and infiltrating macrophages following moderate controlled cortical impact (CCI) in C57Bl/6 mice. Our data in transgenic Cx3Cr1‐GFP microglial and Ccr2‐RFP demonstrated accumulation of autophagosomes and inhibition of autophagy flux specifically in the activated microglia and infiltrating macrophages starting by day 1 and continuing through day 28 post‐CCI. We used flow cytometry analysis to demonstrate that immune cells with inhibited autophagy flux after CCI expressed increased levels of pro‐inflammatory markers, including IL‐1 and TNF‐, as compared to corresponding immune cells with normal levels of autophagy. These trends persisted through day 28‐ post CCI, suggesting that autophagy flux impairment following TBI has long‐term consequences. Consistent with ability of autophagy to affect inflammation, our in vitro experiments in microglial and macrophage cell lines demonstrated that inhibition of autophagy can potentiate pro‐inflammatory activation. In vivo, mice with microglia/macrophage‐specific knockout of the autophagy gene Becn1 (Beclin1flox/flox,LysMCre/Cre) showed increased expression of pro‐inflammatory genes and proteins, and poorer behavioral outcomes as compared to LysMCre/Cre controls after CCI. Overall, these findings indicate that inhibition of autophagy in microglia/macrophages exacerbates neuroinflammation after TBI and contributes to functional deficits.
Keywords: Neuroprotection, Microglia, Aging, Blood Brain Barrier, Inflammation/Immune Function
NEUROPROTECTIVE EFFECTS OF TREHALOSE IN A SEVERE TRAUMATIC BRAIN INJURY MODEL IN MICE
1Neurotrauma and Biomarkers Laboratory, Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil, 2Departamento de Ciências Morfológicas, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil, 3Experimental Research Unit, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brasil
Traumatic brain injury (TBI) is a leading cause of death and disability. Following injury, mitochondrial dysfunction supports long‐term neurodegeneration. Autophagy is the main mechanism of mitochondrial recycling, and it is impaired in TBI. Here, we investigate the neuroprotective effects of trehalose, an autophagy inducer, over mitochondrial function after severe TBI in mice using the controlled cortical impact model. Briefly, 60 male adult C57BL6J mice were separated into three groups: one SHAM group, and two severe cortical impact groups; one with free access to water (CCI) and another to a 3% trehalose solution (TRE) until euthanasia. Three days following injury high‐resolution mitochondrial respiration, calcium handling, and membrane potential assessments in ipsilateral synaptosomes were performed. Lysosomal and mitochondrial content was assessed through flow cytometry analysis of ipsilateral hemisphere homogenates. A separate cohort of mice was euthanized on day 15 to evaluate memory in the Morris' Water Maze. Statistical significance was calculated using two‐way analysis of variance (ANOVA), considered when p < 0.05, and all procedures were approved by the local ethics committee. A decrease was observed in the mitochondrial and lysosomal content in CCI, which was attenuated on the TRE group. Reduced mitochondrial complexes I and II respiration, excessive calcium influx and decreased efflux capacity, and reduced mitochondrial membrane formation were observed in the CCI group, and were prevented in TRE. Spatial memory was impaired in the CCI group and was attenuated by TRE. Our study suggests that trehalose mitigates the effects of secondary damage through the modulation of autophagic function and mitochondrial metabolism.
Keywords: Secondary Injury, Therapeutics/Drug Discovery, Metabolism/Energetics
CLOSED‐HEAD INJURY INCREASED AVOIDANCE IN RATS
1University of Puerto Rico, Río Piedras, San Juan, United States, 2Department of Anatomy & Neurobiology, University of Puerto Rico, School of Medicine, San Juan, United States
The most common form of brain injury, concussion, is frequently seen in contact sports and military combat. Converging lines of evidence suggest that concussion may impair fear‐related behaviors. One type of fear‐related behavior, avoidance, occurs when the need to escape from difficult situations such as an aversive stimulus (i.e. footshock) is presented in the presence of a reward (i.e. sucrose pellets). The effects of concussion on avoidance remains unknowns. Concussion can be modeled in rodents with a closed head injury (CHI). Here, a guide tube is placed above the head of anesthetized rats, and a weight is dropped through the tube. In the current study, we hypothesize that CHI will impair avoidance. One hour after CHI or Sham injury, locomotion behaviors were assessed in an open field to test for motion deficits, and CHI did not affect the distance travelled. In the platform‐mediated avoidance, rats were conditioned in an operant chamber to auditory tones co‐terminating with a mild footshock. An acrylic platform in the opposite corner of the sucrose‐delivering bar allowed rats to avoid the shocks. Animals that underwent a CHI spent more time on the platform throughout the test session during the absence of the tone, even though they learn previously that the absence of tone was a safe period. These suggesting that brain injury results in excess avoidance (p = 0.0127). The translational relevance of this work suggests that brain injury may contribute to mental health disorders, since excess avoidance is characteristic of patients with fear and anxiety disorders
Keywords: Behavioral Function, Concussion/mTBI
ALTERATIONS IN FEAR EXTINCTION AND CORTICAL FUNCTION FOLLOWING MILD TRAUMATIC BRAIN INJURY
1University Of Pennsylvania, Philadelphia PA, United States, 2Children's Hospital of Philadelphia, Philadelphia PA, United States
Traumatic brain injury (TBI) is a leading cause of death and disability in children and adults in the United States. 10‐15% of mild TBI (mTBI) survivors develop neuropsychiatric disorders such as posttraumatic stress disorder, making them a significant public health concern. Notably, an inability to suppress fear and override fearful memories lies at the core of many neuropsychiatric disorders. This ability, known as fear extinction, is essential to mental health. Fear extinction requires learning and remembering that a fear‐evoking object or situation is nonthreatening after it is repeatedly presented without an aversive consequence, thereby creating a retrievable extinction memory. The ability to retrieve fear extinction memories relies on the infralimbic cortex (IL) subregion of the mPFC. Data suggests that the potentiation of IL neurons is necessary for fear suppression and the retention of fear extinction memories. While previous research shows fear extinction is impaired after mTBI in both humans and rodents, little is known of how the IL responds to mTBI. Using a well‐established mouse model of mTBI, this work aims to determine whether mTBIs disrupt the IL neurocircuitry responsible for fear extinction. Preliminary data suggests that during the fear extinction retrieval test session, injured mice freeze more than sham. We further predict injured mice will show reduced IL network activity, a failure to generate long‐term potentiation, and reduced excitability in IL neurons. This work begins to outline the mechanism of injury‐induced fear‐based neuropsychiatric disorders, and lays the groundwork for the development of a treatment for mTBI survivors.
Keywords: Behavioral Function, Cognition/Learning/Memory, Post‐Traumatic Stress, Concussion/mTBI, Electrophysiology
SEX‐SPECIFIC NEUROENDOCRINE DYSFUNCTION AFTER TRAUMATIC BRAIN INJURY IS MEDIATED BY HPA‐ACTIVATION
1University Of California Los Angeles, Neurosurgery, Los Angeles CA, United States
Hormonal dysfunction is a growing concern for women following traumatic brain injury (TBI). This may lead to neuropsychiatric consequences such as anxiety and depression. Dysregulation of sex hormone production may be caused by chronic hypothalamic‐pituitary‐adrenal (HPA) axis activation and/or damage to the pituitary gland. However, this has not been well studied following TBI. Estrus cycle was tracked in adult female Sprague Dawley rats prior to sham craniotomy or moderate controlled cortical impact (CCI) injury and monitored daily thereafter to determine cycle patterns. Plasma was collected at 24hr, 72hr, 1w, 2w, and 5w following injury. Adrenocorticotropic hormone (ACTH), corticosterone (CORT), estrogen (E2), and progesterone (PROG) were quantified via ELISA. A separate group of adult female rats underwent sham or CCI injury, and were injected intraperitoneally with Evans Blue dye (EBD) at 72hr post‐TBI to determine vascular damage. Levels of CORT and ACTH were chronically elevated in CCI rats following injury, while PROG decreased and E2 measurements were inconsistent likely due to differences in estrus stage at time of collection. CCI resulted in an abnormal prolonged state of diestrus. No differences were observed in the tissue concentration of EBD between groups. These data strongly suggest that HPA is the primary factor driving hormone dysfunction in females following TBI.
Keywords: Secondary Injury, Concussion/mTBI, Endocrine
CX3CR1 is a critical neuroinflammatory mediator in degenerative cervical myelopathy
1University Health Network, Toronto, Canada
Degenerative cervical myelopathy is the most common cause of spinal cord impairment worldwide. However, the molecular cascades involved in the induction and maintenance of neuroinflammation resulting from chronic compression of the cervical spinal cord in the setting of DCM have yet to be defined. Here, we determined the role of the fractalkine receptor, CX3CR1, during the neuroinflammatory response in a novel mouse model of DCM and demonstrate the relevance of this mechanism with human DCM tissue. Using CX3CR1 knockout mice and a neutralizing antibody of CX3CR1 in wild type mice, we examined protein, neurobehavioural and immunohistochemical readouts. The animal data were then complemented with immunohistochemical results from human post‐mortem spinal cord tissue from individuals with DCM. Humans and mice with DCM exhibited an up‐regulation of CX3CR1 as well as markers of activated monocytes/microglia in the cervical cord. Knockout and neutralization of CX3CR1 hindered microglia/macrophage activation and accumulation at the site of spinal cord compression. DCM mice exhibited decreased body speed and increased stance phase duration, which mirrors human DCM gait deficits. Strikingly, both CX3CR1 deficiency and CX3CR1 neutralization alleviated these gait deficits in DCM mice. Collectively, these data provide strong evidence that CX3CR1 plays a critical role in the secondary injury of neural structures in the setting of DCM. Further, targeting of CX3CR1 represents a promising therapeutic strategy to enhance neurological outcomes in DCM.
Keywords: Secondary Injury, Microglia, Blood Brain Barrier, Hypoxia/Ischemia, Vascular, Inflammation/Immune Function, Cervical
REPETITIVE TBI SILENCES MEMORY THROUGH ENGRAM CELL SYNAPTIC CHANGES
1Georgetown, Washington DC, United States, 2Trinity College Dublin, Dublin, Ireland
Traumatic brain injury is the most common neurological disorder and 80% consist of mild traumatic brain injury (mTBI). The severity and persistence of cognitive symptoms is increased with additional repeat mTBIs (rmTBI). A high frequency head impact (HFHI) mouse model of rmTBI developed by the Burns lab displays decreased learning and changes in transcriptomic profiles related to synaptic signaling accompanied by decreased plasticity and synaptic changes in CA1 pyramidal neurons. This would suggest that synaptic modifications underly the anterograde cognitive symptoms following rmTBI. It is still unknown how rmTBI directly effects an already established memory. Engrams, defined as lasting physical or chemical changes in neurons, are the neural substrate underlying episodic memory and previous studies have shown that activating this population of neurons can recover amnesia. In this study, we use advances in engram cell labeling to interrogate the mechanisms behind cognitive dysfunction in the repat head impact brain and whether they are treatable. Using a contextual fear conditioning model, we found that the HFHI model confers a retrograde amnesia phenotype but does not result in loss of memory bearing engram cells. Sham animals displayed an engram cell specific increase in spine volume, AMPA/NMDA ratio, and AMPA decay tau that was abolished by HFHI. Upon optogenetic reactivation of the engram, the freezing response was recovered in HFHI, suggesting that memories are silenced, not lost. These data provide mechanistic insights into retrograde amnesia in the repeat head impact brain and warrant a further investigation into functional treatments for cognitive recovery.
Keywords: Cognition/Learning/Memory, Concussion/mTBI, Synaptic Function, Electrophysiology
TREATMENT OF TRAUMATIC BRAIN INJURY IN COMBAT VETERANS
1Tulane University School Of Medicine, New Orleans LA, United States, 2Department of Neurological Surgery, Joan & Sanford I. Weill Medical College, Cornell University, New York NY, United States, 3Department of Neurological Surgery, Rutgers University, Newark NJ, United States
Keywords: Post‐Traumatic Stress, Concussion/mTBI
INVESTIGATION OF GLYMPH TO LYMPH DRAINAGE IN A TBI RAT MODEL
1Georgia Institute of Technology, Atlanta GA, United States
Nearly 70 million people worldwide are estimated to sustain a traumatic brain injury (TBI) each year. New findings show the glymphatic system facilitates interstitial fluid/cerebrospinal fluid (CSF) exchange and is likely contiguous with the cervical lymphatic system. There is a drainage system in which fluid, waste products, macromolecules, and immune cells from the brain exit to the deep cervical lymph nodes (CLNs). Here, we seek to investigate how glymphatic‐lymphatic function is altered in TBI. Rats received either a repetitive closed head mild TBI with a pneumatic impact device with 3 impacts at 2‐minute intervals (5 m/s and head displacements of 5, 2, and 2 mm; N = 6), or sham procedures (N = 8). After 24 hrs, we injected 7 L 20 kDa PEG‐linked infrared dye into the right lateral ventricle (RLV) and used near‐infrared (NIR) imaging through the skull to quantify signal‐to‐noise ratio (SNR) and appearance time of NIR dye in the RLV. TBI animals yielded a lower SNR compared to sham, while NIR dye appears faster to the RLV in TBI animals (t = 26.67 min; sham: t = 30.25 min). Post‐mortem imaging reveals that NIR dye is not present in the deep CLNs in TBI animals in contrary to sham. Our preliminary data suggest that administration of 20 KDa tracer targets lymphatics that are downstream of the drainage of CSF from the brain. Future studies will investigate how these kinetics/routes might differ for smaller tracers and further establish how lymphatic function is altered in TBI. Support: R01NS101909.
Keywords: Edema, Imaging, Biomechanics, Cervical
EVALUATION OF THE THERAPEUTIC EFFECTS OF MYELOTOMY ON RAT CERVICAL SPINAL CORD USING MRI
1Medical College Of Wisconsin, Milwaukee WI, United States
Keywords: Imaging, Axonal Injury, Monitoring
CHARACTERIZATION OF A RAT MODEL OF REPETITIVE MILD FLUID PERCUSSION INJURY AT 2 WEEKS POST‐INJURY
1University of Pittsburgh, Pittsburgh PA, United States, 2VA Pittsburgh Healthcare System, Pittsburgh PA, United States
Repetitive mild traumatic brain injury (rmTBI) is a prominent public health concern, with linkage to debilitating chronic sequalae. Developing reliable and well characterized preclinical models of rmTBI is imperative in the investigation of the underlying pathophysiological mechanism, as models can have varying parameters, affecting the overall pathology of the resulting injury. The fluid percussion injury (FPI) model is a reliable method of rmTBI replication in rodent subjects, though it is currently underutilized in rmTBI research. In this study, we have performed a novel characterization of a variation of the repetitive mild FPI (rmFPI) model, showing the graded acute behavioral impairment and histopathology occurring in response to one, two or four mild FPI (1.25 atm) or sham surgeries, implemented 24h apart (n = 12 per group). Beam balance and Morris water maze performances revealed significant impairment in injured groups, with severity increasing with additional injury. Qualitive analysis of contusion formation, assessed by Cresyl violet staining (n = 6), revealed overt cell loss following four FPI only, which led us to further characterize the subacute pathophysiological outcomes of the dual FPI (dFPI) (n = 6), as this injury demonstrated compounding behavioral dysfunction, while showing no overt lesion formation. Immunoreactivity measures showed that dFPI led to no significant changes in synaptic density two weeks post‐injury, as measured by synaptophysin abundance, but did lead to a striking increase in Iba‐1‐positive microglia in several brain regions. With this characterization, we have provided a novel account of post‐injury outcomes occurring in response to a rmFPI with these parameters.
Keywords: Behavioral Function, Cognition/Learning/Memory, Concussion/mTBI, Synaptic Function
AMYLOID‐β AND TAU IMAGING IN CHRONIC TRAUMATIC BRAIN INJURY: A CROSS‐SECTIONAL STUDY
1Monash University, Caulfield North, Australia
Keywords: Aging, Neurodegeneration, Neuropathology
DIGITAL SPATIAL PROTEOMIC PROFILING IDENTIFIES REGION SPECIFIC CHANGES FOLLOWING REPETITIVE MILD TRAUMATIC BRAIN INJURY IN MICE
1University of Florida, Gainesville GA, United States
Repetitive mild traumatic brain injury (rmTBI) is one of the most frequent and diagnostically elusive type of brain traumas due to the injury's heterogeneity and observed phenotypic outcome. This is partly due to compensatory mechanisms, selective vulnerability of brain regions, and the variability in how frequently the injuries are sustained. Moreover, rmTBIs are associated with risk for numerous dementias including Alzheimer's disease and Parkinsonisms, among other tauopathies and synucleinopathies. A common pathological feature of rmTBIs is axonal injury and damage to white matter integrity, widespread neuroinflammation, and cellular structural damage. Unlike the cases of single injuries, a major clinical challenge for patients sustaining rmTBIs is lack of reliable biomarkers. Given that rmTBIs disrupt white matter integrity, and that head injuries promote neuroinflammation and neurodegenerative processes, we hypothesized that rmTBIs modify these proteomes in a region‐specific manner. Furthermore, we expected these proteins to be differentially expressed in white matter tracts. Isolation of these structures present technical challenges that may produce inconsistent results and impact translational value. To address this issue, we measured changes in proteomic profiles using NanoString GeoMx™ multiplex digital spatial profiler in brains of mice subjected to rmTBI via the Closed‐Head Impact Model of Engineered Rotational Acceleration (CHIMERA). We detected changes in protein profiles associated with Alzheimer's, Parkinson's, glial phenotypes, and autophagic protein pathways post injury. Our data suggest that spatial distribution of brain damage following rmTBIs varies by brain region, and using spatial profiling will enable identification of novel biomarkers that predict outcomes and neurodegenerative processes.
Keywords: Biomarker, Secondary Injury, Imaging, Axonal Injury, Concussion/mTBI, Neuronal‐Glial Interactions, White Matter
CHANGES IN SUPERIOR FRONTAL CORTEX STRUCTURE ARE ASSOCIATED WITH HEAD IMPACT EXPOSURE IN A SEASON OF COLLEGIATE CLUB ICE HOCKEY
1Ludwig‐Maximilians‐Universität München ‐ University of Munich, Munich, Germany, 2University of Delaware, Newark DE, USA, 3Brigham and Women's Hospital, Boston MA, USA, 4Harvard Medical School, Boston MA, USA
SFC volume and thickness were segmented from MPRAGE images using FreeSurfer. A nonlinear inversion algorithm calculates viscoelastic shear stiffness from MRE displacement fields. SFC masks were generated by registering MPRAGE images to the corresponding MRE data. Wilcoxon signed‐ranks tests was performed to examine pre‐to‐post‐season differences in SFC volume, thickness, and stiffness. Pearson correlations examined the relationship between these significantly different measures and the number of impacts sustained.
Keywords: Imaging, Concussion/mTBI, Neuropathology
TRAIN YOUR BRAIN: A PATIENT‐PARTNERED STUDY TO DETERMINE IF THREE‐DIMENSIONAL MULTIPLE‐OBJECT TRACKING IMPROVES COGNITIVE FUNCTION IN INDIVIDUALS WITH MODERATE TO SEVERE BRAIN INJURY
1University of Victoria, Victoria, Canada
Traumatic brain injury (TBI) is a leading cause of death and disability globally. Each TBI is unique; however, attention and memory are commonly impacted. Three‐Dimensional Multiple Object Tracking (3D‐MOT) is an adaptive cognitive training tool that shows promise for individuals with TBI. In this patient‐partnered study, thirteen TBI survivors were randomly assigned to a five‐week waitlist‐control or intervention group. The intervention consisted of two 3D‐MOT sessions per week. Various patient‐partner‐identified cognitive functions were examined before and after the five weeks. TBI survivors demonstrated an average 124% improvement on 3D‐MOT, an improvement similar to cognitively healthy individuals. Estimation statistics were used for all analyses, 5000 bootstrap samples were taken, and the confidence intervals were bias‐corrected and accelerated. Results are presented as (mean‐difference from pre‐intervention to post‐intervention [95%CI]), (mean‐difference from pre‐waiting period to post‐waiting period [95%CI]). The intervention group had decreased proactive interference on the CVLT compared to the waitlisted group (‐0.332 [95CI ‐0.873; 0.0523]) (0.161 [95CI ‐0.0846; 0.435]). The intervention group had greater inhibition on the STROOP task, demonstrated by fewer trial repetitions at the follow‐up time point (‐1.78 [95CI ‐4; ‐0.556]) (2.0 [95CI ‐0.75; 4.75]). The intervention group had improved digit span sequencing scores following the intervention (1.67 [95CI 0.111; 3.22]) (‐0.5 [95CI ‐1.75; 0.277]), and demonstrated greater verbal fluency (3.56 [95CI ‐7.56; 15.1]) (‐3.25 [95CI ‐9.0‐6.64]. The intervention group's TBI‐related symptoms decreased near 50% (‐15.9 [95CI ‐36.6; 4.89]) (3.25 [95CI ‐8.25; 12]). TBI survivors can learn a 3D‐MOT task, and this training may improve various TBI‐related cognitive challenges.
Keywords: Rehabilitation, Cognition/Learning/Memory, Executive Function, Attention
LONG‐TERM FATE OF HIPPOCAMPAL ASCL1‐DERIVED NEURAL PROGENITOR CELLS IN THE CONTEXT OF TBI
1University of Kentucky College of Medicine, Lexington KY, United States, 2University of Kentucky Department of Physiology, Lexington KY, United States , 3Spinal Cord and Brain Injury Research Center , Lexington KY, United States
Keywords: Cognition/Learning/Memory, Imaging, Neurogenesis
NEURO‐FILAMENT LIGHT AND GLIAL FIBRILLARY ACIDIC PROTEIN CHANGES THROUGHOUT A HIGH SCHOOL SPORTS SEASON
1Indiana University ‐ Bloomington, Bloomington IN, United States
This study investigated the time‐course trend of serum neurofilament‐light (NfL) and glial fibrillary acidic protein (GFAP) over the course of a high school football season. A total of 99 healthy high school American football players participated in the study and attended data collection sessions at preseason, three mid‐season time points (August, September, and October), and a post‐season follow up. At each time point, blood was collected from the upper arm using Tasso‐SST devices. Blood samples clotted for 30 minutes at room temperature before centrifugation. Serum was aliquoted and stored at ‐80C until analysis. NfL and GFAP were measured using Simoa® assay kits and a Quanterix SR‐X™ Biomarker Detection System. Changes in biomarker expression across the season were assessed using mixed‐effect regression models. Serum GFAP was significantly elevated at all mid‐season time points (August: B = 9.71, SE = 3.46, p = 0.005; September: B = 19.70, SE = 3.37, p < 0.001; October: B = 25.74, SE = 3.40, p < 0.001) and at post‐season follow up (B = 12.43, SE = 3.39, p < 0.001), compared to preseason baseline. Serum NfL was significantly elevated at the October mid‐season time point (B = 1.44 [SE = 0.59], p = 0.017) compared to preseason baseline. However, NfL concentrations at the August and September mid‐season time points, in addition to the post‐season follow up, did not significantly differ from baseline. These findings suggest that football players may experience astrocyte activation, as indicated by sustained elevation of GFAP levels, which persisted past the end of the season. Additional investigation is needed to understand the late season increase in serum NfL and, more broadly, the relationship between blood biomarker expression and contact sports participation.
Keywords: Biomarker, Blood Brain Barrier, Concussion/mTBI
SELECTIVE REMOVAL OF ASTROCYTIC RELA BLUNTS TBI‐INDUCED NEUROINFLAMMATION AND COGNITIVE DYSFUNCTION
1University Of Kentucky Department of Neuroscience, Lexington KY, United States, 2University of Kentucky Sanders‐Brown Center on Aging, Lexington KY, United States, 3University of Kentucky Spinal Cord and Brain Injury Research Center, Lexington KY, United States
Inflammatory roles of astrocytes in TBI remain controversial as both beneficial and detrimental functions have been reported. In the current study we sought to examine whether canonical NFκβ signaling via RelA is a driver of maladaptive responses of astrocytes in both cell‐ and non‐cell autonomous inflammatory signaling. We have created a novel astrocyte‐specific conditional knockout (cKO) of RelA using the Aldh1l1‐Cre/ERT2 line that simultaneously expresses tdTomato reporter (Ai9). Approximately 3‐month‐old wildtype (WT; Aldh1l1‐Cre/ERT2+/‐Ai9FL/+) and cKO (Aldh1l1‐Cre/ERT2+/‐Ai9FL/+RelAFL/FL). Following a 2‐week washout of tamoxifen administration, mice received either sham or mild‐moderate CCI surgeries and examined at acute (3d) or chronic (28d) post‐surgery intervals. Acutely, we examined astrocyte‐ and microglia‐specific transcriptional signatures using FACS‐mediated enrichment of these cell populations coupled with Nanostring gene arrays. RelA‐knockout in astrocytes blunts multiple TBI‐induced downregulation of homeostatic/synaptic support genes (e.g. Agt, Slc6a1, Gja1, and Kcnj10) as well as pro‐inflammatory response (e.g. Ccl2 and Tnfa). In parallel, we also observed non‐cell autonomous regulation of microglial response, such that genes associated with “DAM” microglia phenotypes were blunted (e.g. Spp1, Clec7a), as well as restoring Tgfbr1 expression, and dampening Il1b responses in mice lacking RelA in astrocytes. Chronically (28d), injured cKO mice had diminished cognitive impairment (i.e. less errors) in the radial arm water maze, compared injured WT mice. Furthermore, cKO mice showed significant sparing of tissue loss relative to WT. Collectively, our data demonstrate that hindering astrocyte usage of RelA dampens the neuroinflammatory milieu, which may be linked to tissue sparing and ultimately dampening TBI‐induced cognitive impairment.
Keywords: Behavioral Function, Astrocyte, Microglia, Cognition/Learning/Memory, Aging, Genetic Factors, Gene Expression, Concussion/mTBI, Inflammation/Immune Function, Growth Factors/Cytokines
CHRONIC SLEEP DISRUPTION AS A PROGNOSTIC BIOMARKER OF COGNITIVE RECOVERY FOLLOWING TRAUMATIC BRAIN INJURY
1Center for Brain Injury and Repair, Department fo Neurosurgery, University of Pennsylvania, Philadelphia PA, United States, 2Center for Neurotrauma, Neurodegeneration, and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia PA, United States
Keywords: Biomarker, Sleep, Cognition/Learning/Memory, Electrophysiology
Poster Abstracts
TRAUMATIC BRAIN INJURY EVOKES IMPAIRED STRUCTURE AND FUNCTION IN THE CEREBELLUM OF GYRENCEPHALIC ANIMALS
Kyle Manetz1, Ms. Adedunsola Obasa1, Mrs. Mitali Chatterjee1, Dr Susan Schwerin1,
1Uniformed Services University of the Health Sciences, Bethesda MD, United States
Traumatic brain injury (TBI) occurs for multiple reasons and shows symptoms that persist for years. To study this problem, we constructed an injury model that mimicked experiences of those in warfare, which can result in TBI. The model included 2 types of injury (blast and strong rotation of the head) with or without stress. The ferret is the smallest mammal with a gyrencephalic cerebral cortex, making it an excellent animal for these studies. We included groups of Sham, Injured (including both injury types) and Injured + Stress, who survived for 4 weeks or 6 months. The cerebellum is a neural center that mediates several functions, including motor coordination, but also higher operations such as cognition, emotion, and sleep. Despite its functional importance, this region is not well studied after TBI. We evaluated the cerebelli of ferrets after TBI using histological, biochemical, and behavioral measures. We found strong pathology in Purkinje cells, especially for the animals surviving for 6 months. These cells showed diminished reactivity for calbindin, especially in the soma and/or dendrites. Disrupted Purkinje cells occurred throughout the posterior lobe for animals surviving 6 months, and in spotty regions for those with shorter survival time. In the longer surviving animals, western blots revealed increases in phosphorylated tau, a protein often involved in neurodegenerative diseases. Behavioral studies revealed surprisingly little motor involvement, but showed deficits in memory and socialization. Overall our study establishes chronic cerebellar neuropathology after a TBI, accompanied by behavioral deficits, and underlines cerebellar significance in multiple functions.
Keywords: Astrocyte, Blast, Neuropathology
POST‐TRAUMATIC EPILEPSY DELAYS RECOVERY FROM SEVERE TRAUMATIC BRAIN INJURY
1UPMC, Pittsburgh PA, United States
Keywords: Epilepsy/Seizure
MIR‐223‐3P DEFICIENCY LEADS TO IMPAIRED AUTOPHAGY THROUGH STAT3 AND ENHANCED PROINFLAMMATORY RESPONSES IN BONE MARROW‐DERIVED MACROPHAGES
1SCoBIRC, University of Kentucky, Lexington KY, United States, 2Neuroscience, University of Kentucky, Lexington KY, United States, 3Sanders Brown Center on Aging, University of Kentucky, Lexington KY, United States, 4Pathology & Laboratory Medicine, Lexington KY, United States
Autophagy is a fundamental catabolic process associated with various eukaryotic cellular events including development, differentiation, immunity, and aging. This highly conserved process plays a significant role in neuroinflammatory responses by modulating inflammatory cell homeostasis, as well as influencing the synthesis and secretion of various cytokines. Autophagy is a well‐organized, multistep, and highly regulated process involving many molecular players including microRNAs (miRNAs). miRNAs are a class of small non‐coding RNAs that regulate various physiological and pathological processes. miR‐223‐3p plays a key role in monocyte/macrophage differentiation and inflammatory responses. However, the role of miR‐223‐3p as a mediator of autophagy remains elusive. Here, we report that the deficiency of miR‐223 enhances the pro‐inflammatory response of bone marrow‐derived macrophage (BMDMs) to inflammatory challenge. Specifically, levels of the autophagy regulators STAT3 and MCL1 were significantly increased in BMDMs isolated from miR‐223 knockout (KO) mice following inflammatory stress compared to wild type BMDMs. Corresponding to the increased expression of STAT3 and MCL1 in the miR‐223 KO BMDMs cells, autophagy was significantly compromised as there was an increased accumulation of the autophagy adaptor protein p62 and decreased level of the autophagy markers LC3‐I and LC3‐II in the miR‐223 depleted BMDMs. Transfection of KO BMDMs with a miR‐223‐3p mimic resulted in normalized STAT3 and MCL1 levels and restored autophagy. More importantly, replenishing miR‐223‐3p resulted in a significant decrease in several major pro‐inflammatory genes. These observations support our hypothesis that miR‐223‐3p regulates autophagy via targeting of STAT3, and this regulation may contribute to inflammatory responses of monocytes/macrophages.
Keywords: Cell Death, Inflammation/Immune Function
EVALUATION AND VALIDATION OF PANEL OF BLOOD‐BASED BIOMARKERS AS NOVEL, TRANSLATIONAL OUTCOMES FOR PRECLINICAL TBI MODELS: AN INTERIM REPORT FROM THE TOP‐ NT PRECLINICAL CONSORTIUM STUDY
1University of Florida, Gainesville GA, United States, 2UCLA, Los Angeles CA, United States, 3Georgetown University, Washington DC, United States, 4John Hopkins University, Baltimore MD, United States, 5UCSF, San Francisco CA, United States
APPROACH/RESULTS: For the biomarker component, during the “Discovery UG3 phase” of the project, two sites have proposed to evaluate potential biomarkers with several TBI model) as follows: GFAP, ALDOC, NF‐L, pNF‐H, Tau, P‐Tau, c‐fibronectin. Serial serum samples were collected biomarkers were assayed and then evaluated for robustness based on these criteria: effect size, area under the ROC (TBI vs. control), linkage to pathophysiological mechanisms in the brain (immunohistochemical and MRI), and correlation to brain tissue level. Five markers (GFAP, ALDOC, NF‐L, Tau, P‐Tau ) were advanced to the UH3 validation phase.
For the on‐going UH3 validation, (i) biosample collection and biomarker assay methods were first harmonized across sites with standard operation procedure. (ii) markers‐relevant preclinical CDE were generated, including biomarker units, assay/ instrument type, sample type/time and QC elements.
Each site (JHU, GU, UCLA, UF) first conducted CCI at two injury magnitudes , followed by FPI/CHIMERA. Biomarker data are generated on Day 1,7 and 30 serum and terminal brain tissue (cortex, hippocampus) samples at UCLA (GFAP, ALOC) and UF (GFAP, NFL, tau, P‐Tau). Validation will include comparing biomarkers profile across‐sites, correlation to (immunohistochemistry, brain levels, MRI and neurobehavior endpoints by the UCSF bioinformatic team. We aim is to increase access/adaptation/usage of validated biomarkers as animal TBI outcome measures.
Keywords: Biomarker, Astrocyte, Axonal Injury, Cell Death
COMPARISON GROUPS MATTER IN TRAUMATIC BRAIN INJURY RESEARCH: AN EXAMPLE WITH RISK OF DEMENTIA
Dr. Jennifer Albrecht1,
1University of California San Francisco and San Francisco VA Medical Center, San Francisco CA, United States
The association between traumatic brain injury (TBI) and risk for Alzheimer's disease and related dementias (ADRD) has been investigated in multiple studies yet reported effect sizes have varied widely. Choice of the unexposed or comparison group is critical to estimating total associated risk. For example, large differences in characteristics between individuals with and without TBI could result in spurious associations between TBI and poor outcomes, even when control for confounding is attempted. Yet, inadvertent control for post‐TBI exposures (e.g., psychological and physical trauma) could result in an underestimate of the effect of TBI. The objective of this study was to highlight how selection of the comparison group impacts estimates of the effect of TBI on risk for ADRD. Using data on veterans aged ≥55 years obtained from the Veterans Health Administration (VA) for years 1999‐2019, we compared risk of ADRD between veterans with incident TBI (n = 9,440) and 1) the general population of veterans who receive care at the VA (All VA)(n = 119,003); 2) veterans who received care at a VA emergency department (VA ED)(n = 111,342); and 3) veterans who received care at a VA ED for non‐TBI trauma (VA ED NTT)(n = 65,710). In inverse probability of treatment weighted models, TBI was associated with increased risk of ADRD compared to All VA (HR 1.94; 95% CI 1.84, 2.04), VA ED (HR 1.42; 95% CI 1.35, 1.50), and VA ED NTT (HR 1.12; 95% CI 1.06, 1.18). The estimated effect of TBI on incident ADRD was strongly impacted by choice of the comparison group.
Keywords: Cognition/Learning/Memory, Neurodegeneration
FEASIBILITY AND UTILITY OF A FLEXIBLE OUTCOME ASSESSMENT BATTERY FOR LONGITUDINAL TRAUMATIC BRAIN INJURY RESEARCH: A TRACK‐TBI STUDY
The effects of traumatic brain injury (TBI) are difficult to measure in longitudinal cohort studies, as disparate preinjury characteristics and injury mechanisms produce variable impairment profiles and recovery trajectories. In preparation for the Transforming Research and Clinical Knowledge in TBI (TRACK‐TBI) study, which followed patients with injuries resulting in uncomplicated mild TBI to coma, we designed a multidimensional, Flexible outcome Assessment Battery (FAB). The FAB relies on a decision‐making algorithm that assigns participants to a Comprehensive [CAB] or Abbreviated Assessment Battery [AAB] and guides test selection across all phases of recovery. To assess feasibility of the FAB, we calculated the proportion of participants followed at 2 weeks and at 3, 6 and 12 months (3m, 6m, 12m) post‐injury who completed the FAB and received valid scores. We evaluated utility by examining differences in 6m and 12m Glasgow Outcome Scale‐Extended (GOSE) scores between participant subgroups derived from the FAB‐enabled versus traditional approach to outcome assessment applied at 2w. Among participants followed at 2w (N = 2,094), 3m (N = 1,871), 6m (N = 1,736), and 12m (N = 1,607) post‐injury, 95‐99% received valid completion scores on the FAB, in full or in part, either in‐person or by telephone. Level of function assessed by the FAB‐enabled approach at 2w was associated with 6m and 12m GOSE scores (proportional odds p < 0.001). These findings suggest that the participant classification methodology afforded by the FAB may enable more effective data collection to improve detection of natural history changes and TBI treatment effects.
Keywords: Diagnostics, Neurocritical Care, Consciousness
USING AN ORGANOMETALLIC GOLD COMPOUND TO IMPROVE MITOCHONDRIAL BIOENERGETICS AFTER TRAUMATIC BRAIN INJURY IN MICE
1Department of Neuroscience, University of Kentucky, Lexington KY, United States, 2Spinal Cord and Brain Injury and Research Center, University of Kentucky, Lexington KY, United States, 3Lexington VA Healthcare System, Lexington KY, United States, 4Department of Chemistry, University of Kentucky, Lexington KY, United States
Traumatic brain injury (TBI) is a serious health concern resulting from a bump, blow, or jolt to the head that impairs normal brain function and affects millions of people yearly. Mitochondrial dysfunction is a hallmark of TBI and an enticing target for therapeutic intervention. We utilized the organometallic gold(III) compound, AuPhos‐89, which drives mitochondrial respiration independent of ATP synthesis, by feeding electrons to Complex‐I of the electron transport chain. Male mice received CCI or sham surgery, and at 15 minutes and 47 hours post‐injury were given vehicle or 10mg/kg AuPhos‐89 by IP injection. At 48 hours post‐surgery, hippocampus and cortex mitochondria were isolated for mitochondrial bioenergetic analysis from the first cohort of mice. Results showed impaired states three and five cortical mitochondrial respiration in vehicle‐treated mice relative to sham, and no significant difference between AuPhos‐89‐treated mice relative to sham. Another cohort was used for the novel object recognition (NOR) assay 1, 2, and 3 days post‐injury, which received treatment 15 minutes, 2 days and 4 days following surgery. AuPhos‐89‐treated mice had a significantly higher recognition index score than vehicle‐treated mice. At 7 days post‐surgery, this cohort was euthanized, and lesion volume and white matter sparing were assessed, revealing there was no significant cortical lesion volume or corpus callosum sparing. AuPhos‐89 shows promise in targeting mitochondria following TBI to improve behavioral and bioenergetic outcomes, but more research needs to be done in the optimal dosing, long term and pathological effects of this treatment.
Keywords: Cognition/Learning/Memory, Therapeutics/Drug Discovery, Metabolism/Energetics
THE MECHANISM OF NEUROPROTECTION OF CD1D DEFICIENCY IN SPINAL CORD INJURY
1Indiana Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, 2Department of Neurological Surgery, 3Department of Microbiology and Immunology, 4Department of Anatomy, Cell Biology and Physiology, 5Indiana University School of Medicine, Indianapolis IN, United States
CD1d is the presentation of lipid antigens to natural killer T cell (NKT). CD1d/NKT axis plays important role in inflammation/immune response. In our previous study, we found CD1d deficiency could significantly promote functional recovery and protect neurons, reduce lesion area, and demyelination of white matter after spinal cord injury (SCI). In this study, we investigated the mechanism of neuroprotection with thoracic 10 contusive mouse model. At 1‐, 3‐, 7‐, and 35‐days (dpi) after SCI CD1d deletion significantly reduced pro‐inflammation cytokine IL‐6 by 3.5, 4.0, 2.9 and 2.3 folds. IFN‐γ, IL‐α and TNF‐α decreased by 45%, 38%, and 25.4%, the chemokine Eotaxin reduced by 59% at 1dpi. However, in CD1dKO mice anti‐inflammatory cytokine IL‐4 increased by 132% and 223%, vascular endothelial growth factor (VEGF) increased by 278% and 446% at 1 and 3dpi. The activated inflammatory cells microglia/macrophages were reduced by 26.3%, 65.5%, 44.8%, 38% and 43.2% at epicenter (Epi.) and 500/1000 μM both rostral and caudal away from Epi. Further, we investigated whether this inflammatory response reduction was through CD1d/NKT axis. We compared the SCI Traj18KO mice which NKT cell deficiency with WT SCI mice. All the functional assessments of Traj18KO were not improvement which showed in CD1dKO mice. Moreover, administration of the NKT activator α‐galactosylceramide (α‐GalCer) after SCI did not exacerbate functional deficits. All these data indicate the mechanism of neuroprotection of CD1d deficiency is CD1d‐dependent inflammation reduction, but not via conventional CD1d/NKT axis.
Keywords: Neuroprotection, Behavioral Function, Secondary Injury, Microglia, Inflammation/Immune Function, Growth Factors/Cytokines
ROLE OF CARDIOLIPIN ALTERATION IN THE PATHOGENESIS OF SPINAL CORD INJURY
1Indiana University School of Medicine, Indianapolis IN, United States, 2University of Pittsburgh, Pittsburgh PA, United States, 3University of Texas Health Science Center at San Antonio, San Antonio TX, United States
Although alterations in phospholipids have long been associated with spinal cord injury (SCI), their specific roles and signaling cascades in mediating damage are not well understood. Here we explored the role of cardiolipin (CL), a family of mitochondrion‐specific phospholipids, in the pathogenesis of SCI in a moderate contusive SCI model in the adult rats. Lipidomics analysis showed CL alterations at an early stage of SCI. Over 50 distinct CL species were identified, of which 50% showed significantly decreased abundance after SCI. The decreased CL species contained mainly polyunsaturated fatty such as acids arachidonic acid (C20:4) (AA), docosahexaenoic acid (C22:6) (DHA), and linoleic acid (C18:2) (LA) fatty acids that are highly susceptible to peroxidation. In parallel, 4‐HNE, a lipid peroxidation marker, significatly increased after SCI. We found that mitochondrial oxidative stress not only induced CL oxidation, but also resulted in CL loss by activating cPLA2 to hydrolyze CL. CL alterations (peroxidation and loss) induced mitochondrial dysfunction and neuronal death. Remarkably, pharmacologic inhibition of CL alterations with XJB‐5‐131, a novel mitochondria‐targeted electron and reactive oxygen species scavenger reduced tissue damage and ameliorated motor deficits after SCI in rats. These findings suggest that CL alteration may play an important role in the pathogenesis of SCI, and as such could be an attractive therapeutic target for ameliorating secondary SCI.
Keywords: Neuroprotection, Cell Death, Free Radicals
LATENT NEUROPSYCHOLOGICAL PROFILES ARE BETTER THAN STRUCTURAL NEUROIMAGING PROFILES IN DIFFERENTIATING ACTIVE‐DUTY MILITARY SERVICE MEMBERS WITH MILD TRAUMATIC BRAIN INJURY AND POST‐TRAUMATIC STRESS DISORDER
1Rutgers Biomedical and Health Sciences, Newark NJ, United States, 2Brigham Young University, Provo UT, United States, 3University of Utah, Salt Lake City UT, United States, 4George E. Wahlen Veterans Affairs Salt Lake City Healthcare System, Salt Lake City UT, United States, 5Pennsylvania State University, University Park, United States, 6San Antonio VA Polytrauma Rehabilitation Center, San Antonio TX, United States, 7Brooke Army Medical Center, Houston TX, United States, 8Wright State University, Dayton OH, United States, 9Alaska Radiology Associates, Anchorage AK, United States, 10Michael E. DeBakey VA Medical Center, Houston TX, United States, 11Baylor College of Medicine, Houston TX, United States
Mild traumatic brain injury (mTBI) and post‐traumatic stress disorder (PTSD) commonly occur among military Service Members and Veterans and have heterogenous, but also overlapping symptom presentations, which often complicate the diagnoses of underlying impairments and development of effective treatment plans. Thus, we sought to examine whether the combination of whole brain gray matter (GM) and white matter (WM) structural measures with neuropsychological performance can aid in the classification of military personnel with mTBI and PTSD. Active‐Duty U.S. Service Members (n = 156; 87.8% male) with a history of mTBI, PTSD, combined mTBI+PTSD, or orthopedic injury completed a neuropsychological battery and T1‐ and diffusion‐weighted structural neuroimaging. Cortical, subcortical, ventricular, and WM volumes and whole brain fractional anisotropy (FA), mean (MD), radial (RD), and axial diffusivity (AD) were calculated. Latent profile analyses were performed to determine how the GM, WM, and neuropsychological indicators classified individuals. For both GM and WM respectively, a four‐profile model was the best fit. The GM model identified greater ventricular volumes in Service Members with cognitive symptoms, including those with a diagnosis of mTBI, either alone or with PTSD. The WM model identified reduced FA and elevated RD in those with psychological symptoms, including those with PTSD or mTBI and comorbid PTSD. However, contrary to expectation, a global neural signature unique to those with comorbid mTBI and PTSD was not identified. This finding demonstrates that neuropsychological performance alone is more robust in differentiating military personnel with mTBI and PTSD, whereas global neuroimaging measures do not reliably differentiate between these groups.
Keywords: Cognition/Learning/Memory, Post‐Traumatic Stress, Concussion/mTBI, White Matter
NON‐ESSENTIAL ROLE FOR CX3CR1‐EXPRESSING EPH RECEPTOR A4 IN A MURINE MODEL OF TBI
1Virginia Tech, Blacksburg VA, United States
Erythropoietin‐producing human hepatocellular (Eph) receptors contribute significantly to central nervous system injury. Our findings demonstrated that Cx3cr1‐expressing cells within the perilesional cortex showed increased levels of EphA4 after induction of controlled cortical impact (CCI) injury in mice. Cx3cr1 is a fractalkine receptor, commonly expressed on resident microglial and peripheral‐derived macrophage (PDM) cells. The aim of this study is to identify the role of microglial‐specific EphA4 in CCI‐induced damage. Cx3cr1CreER/EYFP knock‐in/knock‐out mice expressing EYFP in Cx3cr1+ cells were used to evaluate microglia in EphA4‐deficient mice following 1‐month tamoxifen injections. CCI‐Injured wild‐type (WT) Cx3cr1CreER/EYFP/EphA4+/+ mice displayed increased EphA4 expression on the EYFP‐positive cx3cr1 cells within the peri‐lesion. Immunohistochemical applications were further used to differentiate between the peripheral‐derived macrophage and resident microglia using anti‐Ccr2, which selectively labeled PDMs and not microglia. We then exploited GFP bone marrow chimeric mice to discriminate EphA4 expression on microglia (TMEM119+/GFP‐) versus PDMs (GFP+) following CCI. Finally, the use of Cx3cr1CreER/EYFP/EphA4f/f (KO) mice, which show no detectable transcript for EphA4 in microglia only, demonstrated no discernible difference in lesion volume or blood brain barrier (BBB) disruption when compared to the WT mice. These findings illustrate that although EphA4 is upregulated on cortical microglia after TBI, it plays a nonessential role in acute response following TBI.
Keywords: Neuroprotection, Secondary Injury, Microglia, Neurodegeneration, Blood Brain Barrier, Concussion/mTBI, Neuronal‐Glial Interactions, Inflammation/Immune Function
MITOCHONDRIAL DYSFUNCTION AFTER INJURY TO THE AGING BRAIN
Sadie Ferren1, Jinxiang Hu2, Heather Wilkins3,4,
1KU Medical Center Department of Anatomy and Cell Biology, Kansas City MO, United States, 2KU Medical Center Department of Biostatistics, Kansas City MO, United States, 3KU Medical Center Department of Neurology, Kansas City MO, United States, 4KU Medical Center Department of Biochemistry, Kansas City MO, United States, 5KU Medical Center Hoglund Biomedical Imaging Center, Kansas City MO, United States
Mitochondrial impairment is a critical element of TBI pathophysiology, but our understanding of this injury mechanism in older individuals remains limited. In this study we assessed a time course of injury‐induced functional changes in specific sub‐populations of mitochondria after TBI in young and aged rats. Male and female F344 rats (3 or 21 months old) were randomized to receive a controlled cortical impact TBI or sham surgery. Animals were euthanized 3 or 14 days later and the injured cortex was dissected along with an intact sample from the contralateral cortex. We used fractionated mitochondrial magnetic separation, a recently developed antibody‐based approach, to purify synaptic and non‐synaptic mitochondrial sub‐populations from brain tissue. Mitochondrial respiration was measured with a Seahorse XF Extracellular Flux Analyzer. The synaptic mitochondrial pool showed a larger acute defect in aged rats than in young adults across all respiratory states. Synaptic mitochondria from aged rats also had prolonged deficits in State V respiration compared with younger adults. For the non‐synaptic mitochondrial pool, the time course of State IV respiratory deficits differed by age, and aged rats also had larger and prolonged deficits in State V respiration. Together, these results suggest that older age is associated with greater metabolic disruption after TBI, and that synaptic mitochondria are more sensitive than non‐synaptic mitochondria to the effects of injury and aging. Understanding how age influences mitochondrial dysfunction after brain trauma will help inform and refine therapeutic studies, with the ultimate goal of improving outcomes for TBI survivors of all ages.
Keywords: Aging, Metabolism/Energetics
LOCOMOTOR EXERCISE ENHANCES SUPRASPINAL CONTROL OF LOWER URINARY TRACT ACTIVITY TO IMPROVE MICTURITION FUNCTION AFTER CONTUSIVE SPINAL CORD INJURY
1Indiana University, Indianapolis IN, United States, 2Drexel University, Philadelphia PA, United States
Recovery of lower urinary tract (LUT) activity is a top priority for patients with a spinal cord injury (SCI). Historically, locomotor training (LT) has been shown to improve micturition function in both SCI patients and animal models alike. However, it is unknown whether this effect is attributable to the augmentation of supraspinal control of the external urethral sphincter (EUS) which results in enhanced coordination between detrusor‐sphincter activity. In this study, we implemented a clinically relevant contusive SCI at the 12th thoracic level (T12) in rats and administered with forced wheel running exercise for 11 weeks. Awake rats then underwent bladder cystometrogram (CMG) and EUS electromyography recordings to examine the micturition reflex. Subsequently, pseudorabies virus (PRV) encoding red fluorescent protein were injected into the EUS to transsynaptically trace the supraspinal innervation of Onuf's motoneurons. The results indicated that LT in rats with SCI reduced the occurrence of bladder non‐voiding contractions, decreased the voiding threshold and peak intravesical pressure, and shortened the latency of EUS bursting during voiding, leading to enhanced voiding efficiency. Histological analysis demonstrated that LT increased the extent of spared spinal cord tissue around the epicenter of lesion. Compared to rats receiving SCI without exercise, LT elicited denser 5‐HT+ axon terminals in the vicinity of Onuf's motoneurons in the cord; more PRV‐labeled or c‐fos expressing neurons were detected in the brainstem, suggesting enhanced supraspinal control of EUS activity. Thus, LT promotes tissue sparing and axon innervation of spinal motoneurons to improve LUT function following contusive SCI.
Keywords: Exercise, Regeneration & Plasticity
DEFICITS TO GLYCEMIC CONTROL FOLLOWING SPINAL CONTUSION
1University Of Mississippi Medical Center, Jackson MS, United States
Type 2 diabetes mellitus afflicts spinal cord‐injured individuals at a much higher rate than able‐bodied controls. The mechanisms driving this disparity remain poorly understood. The goal of the current study was to evaluate the impact of diet on glycemic regulation using a moderate contusion model of thoracic spinal cord injury (SCI). Male Long Evans rats were either T10 spinal contused or were naïve to surgery. The animals were provided with high–fat diet (HFD) or standard chow for 16 weeks. Following surgery, animals were analyzed for body weight, body composition and glucose tolerance. Overall, SCI resulted in reduced body weight in comparison to naïve controls. HFD‐fed rats were glucose intolerant, with elevated fasting and elicited glucose and insulin levels. SCI rats also had elevated fasting and elicited glucose and insulin levels. Paradoxically, fasted and elicited total GLP‐1 were elevated and appeared uncoupled to improvements in glycemic control following a mixed‐meal gavage. Pancreatic glucagon protein levels were reduced in SCI in comparison to naïve controls. This was accompanied by elevated glucagon mRNA and GLPR in the pancreas. Both in the hypothalamus and ileum, GLPR gene expression was elevated in SCI in comparison to naïve. In total, these data suggest GLP‐1 signaling may be altered following SCI. More studies are needed to determine the mechanism of dysfunction.
This work is supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number 5U54GM115428.
Keywords: Endocrine, Nutrition, Metabolism/Energetics
CHARACTERIZATION OF SEX DIFFERENCES IN MITOCHONDRIAL DYSFUNCTION AFTER SEVERE CONTROLLED CORTICAL IMPACT IN MICE.
1Department of Neuroscience, University Of Kentucky, Lexington KY, United States, 2Spinal Cord and Brain Injury Research Center, Lexington KY, United States, 3Lexington VA Healthcare System, Lexington KY, United States, 4Department of Physiology, University Of Kentucky, Lexington KY, United States
Traumatic brain injury (TBI) is caused by a blow to the head resulting in abnormal brain function. Mitochondrial dysfunction is a hallmark of TBI and has been thoroughly studied in male rodent models of injury. Relatively little is known about mitochondrial outcomes in females, though current data suggests sex differences. To develop mitochondrial‐based therapeutics to treat TBI patients, it's imperative that we understand this underlying dysfunction in both sexes. Here, male and female mice received sham or CCI surgery followed by bioenergetic assessment of synaptic and non‐synaptic mitochondria from the injured cortex 3, 12, 24, and 48 hours post‐surgery.
The results showed synaptic mitochondria from injured females had 74% ATP production‐driven respiration at 3h, 67% at 12h, 47% at 24h, and 88% at 48h after CCI compared to normalized (100%) sham female values, with significance only at 24h. Non‐synaptic mitochondria from injured females maintained 88‐95% function across time, but were significantly different from sham at 12h and 48h post‐CCI. Synaptic mitochondria from male mice followed an earlier, but similar temporal pattern of bioenergetic dysfunction as females and non‐synaptic mitochondria from males had delayed bioenergetic decreases (81% of sham) starting at 24h post‐CCI. There were no significant changes in oxidative stress marker expression (4‐HNE and 3‐NT) in either mitochondrial fraction between injured and sham or between the sexes 24h post‐CCI. Ongoing studies will further elucidate the mechanism of mitochondrial dysfunction in females after TBI.
NIH NINDS 1R01NS112693‐01A1 (PGS); HHS PHS Ruth L. Kirschstein NRSA T32NS077889 (OJK); Lexington VA Merit BX003405 (PGS).
Keywords: Excitotoxicity, Secondary Injury, Synaptic Function, Metabolism/Energetics
A BIOENERGETICS APPROACH TO STUDY PATHWAY‐SPECIFIC MITOCHONDRIAL METABOLIC DYSFUNCTION AFTER TRAUMATIC BRAIN INJURY
1Spinal cord and Brain Injury Research Center, University Of Kentucky, Lexington KY, United States, 2Department of Neuroscience, University Of Kentucky, Lexington KY, United States, 3Lexington VA Healthcare System, Lexington KY, United States, 4Department of Physiology, University Of Kentucky, Lexington KY, United States
Traumatic brain injury (TBI) results in mitochondrial metabolic dysfunction by affecting the availability and utilization of different energy intermediates. Analysis of mitochondrial bioenergetics is a proven way to study metabolic pathophysiology of TBI. However, use of only few selective substrates limit detailed understanding of the complex metabolic changes after TBI. To study mitochondrial dysfunction after TBI, we developed a high throughput respirometry assay to determine pathway specific utilization of metabolic intermediates as mitochondrial energy substrates. Adult male C57BL/6 mice were subjected to either severe controlled cortical impact (CCI) or sham injury. At 48h mitochondria were isolated from the ipsilateral cortex. Mitochondrial bioenergetics were performed using Seahorse Xfe96 Analyzer (Agilent) in the presence of 10 different substrates (Pyruvate, Glutamate, Succinate, Citrate, Isocitrate, α‐ketoglutarate, Ascorbate, Palmitoyl L‐carnitine, Octanoly L‐carnitine, β‐hydroxy butyrate) metabolized through key metabolic pathways representing TCA cycle, β‐oxidation, ketone and amino acid metabolism. The results demonstrate that in cortex, the state‐III (ADP‐driven), state‐IV (proton leak) and state‐V (uncoupled) mitochondrial respiration rates were significantly decreased in the CCI mice as compared to sham group with all the substrates used except α‐ketoglutarate and Octanoyl‐L‐carnitine. Collectively, our results indicate that the ipsilateral cortex exhibits global mitochondrial dysfunction affecting majority of the mitochondrial pathways. This study will be helpful in determining the mitochondrial functional changes in response to multiple energy intermediates after TBI.
Keywords: Excitotoxicity, Secondary Injury, Metabolism/Energetics
RECENT UPDATES ON THE GHBMC HUMAN HEAD FINITE ELEMENT MODEL – BRAIN STRAIN VALIDATION AND CRASH INDUCED HEAD INJURY INDEX DEVELOPMENT
Ding Lyu1,
1Wayne State University, Detroit MI, United States
The Finite Element Global Human Body Models Consortium 50th percentile (GHBMC M50) adult male head model was refined to incorporate an anisotropic visco‐hyperelastic brain model capable of simulating direction‐dependent impact responses. The material parameters were optimized by matching the model strain responses with those measured in the brains of the Post‐Mortem Human Subjects (PMHS) subjected to head impact. The model was then rigorously validated against force‐deflection responses in the skull and face, intracranial pressure (ICP), and brain maximum principal strain (MPS) measured from 30 PMHS head impact experiments. Crash‐induced Injury Indices (CIIs) based on tissue level response parameters for facial bone fracture, skull fracture, cerebral contusion, acute subdural hematomas (ASDH), and diffuse brain injury were developed by simulating 32 PMHS and real‐world injury cases. The model predicted MPS matched favorably to the PMHS results. The skull and facial bone fracture CIIs for compact and spongy bones were determined to be 0.88% MPS and 20 MPs stress, respectively. The AUC of the risk functions (logistic regression and survival analysis) for cerebral contusion and ASDH was above 0.8. ICP of 161 kPa and bridging vein strain of 0.46 would result in 50% risk of contusion and ASDH. Model predictions of diffuse brain injury (AIS4+) suggested that the strain rate in the white mater (107s‐1) is an essential brain response that discriminates between moderate and severe brain injuries. The current GHBMC M50 v.6 is an advanced tool for injury prediction and mitigation of injuries in automotive crashes, sports, recreational and military environments.
Keywords: Computational/Modeling, Biomechanics, White Matter
A REAL‐TIME SYSTEM TO MONITOR BRAIN STRAIN TO DETECT DANGEROUS HEAD IMPACTS
1Stanford University, Stanford CA, United States
Traumatic brain injury (TBI) is caused by head impacts and physiologically, brain strain and strain rate are key parameters causing TBI pathologies. After years of work, we integrated our previous works in the instrumented mouthguards, the denoising algorithm for head kinematics and the head model to estimate the brain strain and strain rate to a TBI risk monitoring system. Firstly, with 163 laboratory impacts, we developed a deep‐learning denoiser of mouthguard kinematics with one‐dimensional convolutional neural network (1D‐CNN). The models are effective in generating kinematics better correlated with the reference kinematics measured by sensors implanted in the dummy head. The error between the denoised kinematics and the reference kinematics is significantly smaller than that between the raw mouthguard measurement and the reference. Furthermore, the 1D‐CNN denoising models significantly reduce the errors of the strain and strain rate calculation based on the kinematics measurement. Secondly, with 13,623 head impacts from simulations, American football, mixed martial arts, and car crashes, we developed fully connected neural networks (FCNN) to estimate the maximum principal strain (MPS) and MPS rate (MPSR) for 4,124 brain elements and compared the predictions with the reference values given by finite element modeling. The models output the whole‐brain MPS and MPSR within 1ms with a mean absolute error (MAE) smaller than 0.03 in predicting MPS and smaller than 7 (1/s) in predicting MPSR on all impact datasets. The system can be applied to the real‐time brain strain and strain rate monitoring to detect dangerous head impacts with wearable devices.
Keywords: Diagnostics, Computational/Modeling, Biomechanics
TRAUMATIC BRAIN INJURY INDUCED CHRONIC INFLAMMATION AND COGNITIVE IMPAIRMENT IS ATTENUATED BY INHIBITION OF THE TYPE 1 INTERFERON PATHWAY
1The Ohio State University, Columbus OH, United States
Neuropsychiatric complications including depression and cognitive decline develop, persist, and worsen in the years after traumatic brain injury (TBI). Chronic inflammatory processes persist after TBI, but the mechanism that promotes this response is unclear. We previously reported that microglia promoted chronic inflammation following diffuse TBI in mice. Moreover, the subacute phase of cortical inflammation 7 days post injury (dpi) was dominated by a robust type 1 interferon (IFN) response. Thus, we hypothesize that increased IFN signaling is critical in promoting microglial priming and the transition from acute to chronic neuroinflammation after TBI. We targeted the IFN pathway by using knockout mice for the interferon alpha/beta receptor (IFNAR) and the transmembrane protein stimulator of interferon genes (STING). In these experiments, adult male wildtype (WT), STINGKO, and IFNARKO C57BL/6 mice received a TBI and neuroinflammation and functional recovery were assessed 7 and 30 dpi. Inflammatory/priming related genes and IFN genes were increased 7 dpi in the cortex of TBI mice compared to controls, but were attenuated in both IFNARKO mice and STINGKO mice. In STINGKO mice there was reduced microglial activation within the somatosensory cortex and hippocampus (7 dpi). In addition, there was reduced neuroinflammatory related mRNA expression 30 dpi in STINGKO compared to WT TBI controls. Last, the TBI associated deficits in cortical and hippocampal dependent memory in the novel object tasks 30 dpi were attenuated in the TBI‐ STINGKO mice. Taken together, reducing type I IFN signaling after TBI intervention effectively reduces chronic inflammation and improves functional recovery post‐TBI.
Keywords: Microglia, Axonal Injury, Concussion/mTBI, Inflammation/Immune Function
DISTURBANCES IN SLEEP ARCHITECTURE ARE ASSOCIATED WITH POOR COGNITIVE OUTCOME AND QUALITY OF LIFE IN CHRONIC TBI
1Centre For Neuro Skills, Irving CA, United States, 2UCLA David Geffen School of Medicine, Los Angeles CA, United States, 3Inspire Sleep Apnea Innovations, Golden Valley MN, United States
Those who endured a TBI frequently report problems with sleep and diurnal somnolence. We investigated if alterations in sleep architecture were associated with cognitive, social, and emotional health. Methods: TBI patients (n = 58) were assessed via overnight polysomnography. Mean age was 41 years and mean TBI chronicity was 2.3 years. Sleep measures included slow wave sleep (SWS), REM latency, percent time in sleep stages, apnea/hypopnea index (AHI), wake after sleep onset (WASO), and arousal index. Outcome measures included the California Verbal Learning Test (CVLT‐II), Montreal Cognitive Assessment (MoCA), and Neuro‐QoL. Medications taken at the time of the PSG were considered. Results: SWS was lower than age and sex matched norms and was less than 1% of total sleep time in 29% of patients. For those with over 10% SWS, SWS was positively correlated recall measures on the CVLT‐II (p < .05). Men spent significantly more time in REM sleep (p < .05), which was correlated with higher immediate memory scores according to CVLT‐II (p < 0.005). Women reported more fatigue and dissatisfaction across quality‐of‐life measures compared to men (p < 0.05). Respiratory events were more prevalent in men, indicated by higher AHI and obstructive apnea events (p < 0.05). Benzodiazepine use was positively correlated with AHI (r = .3). Hypnotic/Sedative use was positively correlated with sleep efficiency (r = .6) and negatively correlated with WASO (r = ‐.3). Conclusion: Female TBI patients show significant impairments in REM sleep, which is critical for learning and memory. Sleep disturbances were associated with poorer cognitive performance and may ultimately affect outcome, as indicated by lower scores on quality‐of‐life measures.
Keywords: Sleep, Cognition/Learning/Memory
TARGETING OF DUAL ANTIOXIDANT ENZYME CONJUGATES TO THE CEREBRAL VASCULATURE FOR ATTENUATION OF OXIDATIVE STRESS RESPONSES FOLLOWING EXPERIMENTAL TRAUMATIC BRAIN INJURY
1Department of Pathology and Laboratory Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia PA, United States, 2Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, United States
Oxidative stress responses following TBI are key contributors of the secondary injury phase. Specifically high‐energy reactive oxygen and nitrogen species (ROS & RNS) potentiates immune responses, compromises surrounding healthy CNS tissue, and disrupts blood brain barrier (BBB) function. Therefore, we hypothesize that attenuating ROS and RNS at the vasculature after TBI will result in improved BBB integrity and neuroprotection. Utilizing click‐chemistry, dual conjugates (dual AOE/ICAM) consisting of the antioxidant enzymes, superoxide dismutase 1 (SOD1) and catalase, were covalently linked to anti‐ICAM‐1 antibodies. In order to determine that generating the conjugate did not alter antioxidant enzyme function, mouse endothelial cell monolayers were exposed to increasing concentrations of hydrogen peroxide (H2O2) and SIN‐1 (superoxide donor). Concentrations added for 1h, ranged from 50 μM to 1mM and 200μM to 1mM for H2O2 and SIN‐1 respectively. Using the Seahorse Mito Stress Assay, our results show that dual AOE/ICAM effectively mitigated the mitochondrial stress due to oxidative damage. Measured by oxygen consumption rate (OCR), compared to untreated, the dual AOE/ICAM show significant improvements in OCR against H2O2 (p = 0.0018) and SIN‐1 (p < 0.0001). Next, to simulate the oxidative stress response from mechanical injury, a Cytostretcher™(CuriBio) with endothelial cells was used. Addition of the conjugates following a 20% mechanical strain significantly reduced oxidative stress which promoted an accelerated BBB recovery and inhibition of cellular activation. The results presented here suggest that targeted dual AOE/ICAM to the cerebral endothelium may offer a therapeutic avenue for minimizing oxidative stress associated tissue damage in the context of TBI.
Keywords: Secondary Injury, Blood Brain Barrier, Therapeutics/Drug Discovery, Free Radicals
CONSENSUS BIOPSYCHOSOCIAL MECHANISM LINKING PEDIATRIC TBIS TO ADULT INCARCERATION
1Rutgers New Jersey Medical School, Newark NJ, United States, 2Center for Advanced Biotechnology and Medicine, Piscataway NJ, United States, 3Weill Cornell Medical College, New York NY, United States, 4Heersink School of Medicine, Birmingham, United States
Keywords: Behavioral Function, Cognition/Learning/Memory, Executive Function, Concussion/mTBI
SEX‐RELATED DIFFERENCES IN ADULT INCARCERATION FOLLOWING PEDIATRIC TBIS
1Rutgers New Jersey Medical School, Newark NJ, United States, 2Rutgers Robert Wood Johnson Medical School, Piscataway NJ, United States, 3Weill Cornell Medical College, New York NY, Unites States, 4Tulane University School of Medicine, New Orleans LA, United States
Keywords: Pediatric, Behavioral Function, Executive Function, Concussion/mTBI
BEHAVIORAL DEFICITS FOLLOWING REPEAT MILD BRAIN INJURY IN FEMALE ADOLESCENT RATS ARE ACTIVITY DEPENDENT
1University Of California Los Angeles, Los Angeles CA, United States, 2Pepperdine University, Malibu CA, United States
Recovery from repeat mild traumatic brain injury (rTBI) differs between exercised rats (rathletes) and non‐rathletes, and as a result of timing of post‐injury exercise. Adolescent females seem especially prone to depression and impaired social interactions post‐rTBI. Female rats (age 35days) were allowed access to a running wheel for 10 days before rTBI (2x24hr apart) or sham surgery. Following, voluntary exercise varied, either no exercise (sham, rTBI), immediate access (sham, rTBI), or after 3day delay (rTBI). All rats were euthanized at post‐injury day (PID) 10. On PID 1, 3, 5, and 7, rats were tested for motor impairment and anxiety‐like behavior. Injured females did not show any motor impairment on a foot fault test compared to shams at any of the days tested. Anxiety‐like behavior was decreased after injury, particularly on PID 7 as shown by significantly decreased latency to enter and explore an open lit arena. Timing of exercise post‐injury did not affect anxiety measures. Social interactions were tested on PID 8 and results showed reduced interactions overall in all injured rats. Specifically, time spent investigating a novel conspecific was significantly reduced, particularly in rTBI rats with a 3day delay. Rats were also tested for anhedonia using the saccharine test on PID 8‐9. Those rats with a 3d delay to exercise post‐injury showed a reduced preference for saccharine. Overall, these results indicate that timing of post‐rTBI exercise influences recovery in female adolescent rats.
This work was supported by NIH NS110757, the UCLA Brain Injury Research Center, BrainSPORT, and Easton Labs.
Keywords: Pediatric, Behavioral Function, Cognition/Learning/Memory, Depression, Concussion/mTBI, Exercise
ACUTE INTRANASAL INSULIN DELIVERY IMPROVES LONG‐TERM OUTCOME AFTER SPINAL CORD INJURY IN AGED BUT NOT YOUNG RODENTS
1Uniformed Services University, Bethesda MD, United States
Intranasal insulin can rapidly enter the central nervous system and the cerebrospinal fluid to increase glucose uptake and improve functional outcomes in models of brain injury and Alzheimer's Disease. In rodent spinal cord injury (SCI), we previously determined that acute administration of intranasal insulin led to short‐term improvements in motor function in both young adult (3 month) and middle‐aged (12 month) rats. However, the effect of acute insulin delivery on long‐term function outcomes has not been determined. We therefore assessed the long‐term effects of insulin in the young and aged models. Young adult (3 month) and middle‐aged (12 month) male Sprague‐Dawley rats underwent a moderate contusion SCI at T9 (200kdyne) and received daily intranasal administration of insulin or saline from 4 hours to 7 days post injury. Positron emission tomography (PET) scans of 18Fluorodeoxyglucose (FDG) were conducted at baseline and day 28 post‐injury. In both young adult and aged animals, there was a reduction in FDG uptake at 28 days with insulin administration, suggesting a reduction in heavily glycolytic inflammatory cells at the lesion site. Motor function was examined with the Basso‐Beattie‐Bresnahan (BBB) scale weekly through day 28 and DigiGait gait analysis on day 21 post‐injury. BBB scores and analysis of gait demonstrated a significant improvement in hindlimb locomotion in the aged group with insulin; there was no significant improvement observed in young‐adult rats. These data demonstrate that intranasal insulin significantly improves outcome in an age dependent manner, despite similar reductions in inflammation in the lesion site chronically after injury.
Keywords: Aging, Imaging, Inflammation/Immune Function, Metabolism/Energetics
TRANSLATIONAL OUTCOMES PROJECT IN NEUROTRAUMA (TOP‐NT): OVERVIEW ON EXPERIMENTAL STANDARDS AND COMMON DATA ELEMENTS FOR SERUM BIOMARKERS, MULTIMODAL MRI, BEHAVIORAL OUTCOMES, AND QUANTITATIVE HISTOPATHOLOGY FOR ASSESSING TRAUMATIC BRAIN INJURY (TBI) ACROSS DOMAINS
1UCLA, Los Angeles CA, United States, 2BRAINBox Solutions Inc., Richmond VA, United States, 3John Hopkins University, Baltimore MD, United States, 4University of Florida McKnight Brain Institute, Gainesville GA, United States, 5Georgetown University Medical Center, Washington DC, United States, 6Uniformed Services University of the Health Sciences, Bethesda MD, United States, 7UCSF, San Francisco CA, United States
Preclinical TBI research is hampered by non‐uniform models and clinically incompatible tools, limiting comparison, generalization, and translation. Harmonized approaches, including noninvasive assessment, standardized language via common data elements (CDE), and a shareable infrastructure are needed. The TOP‐NT Consortium assembled a coordinated preclinical CDE data dictionary of 415 CDEs (embracing 185, adding 230) including preclinical MRI, biomarkers, and unbiased histopathology. We harmonized SOPs for controlled cortical impact, fluid percussion, and rotational rat TBI models. MRI includes structural, functional, and molecular protocols (fMRI, diffusion tensor‐, amide proton transfer‐weighted and, T2*‐parametric mapping) at multiple post‐injury time‐points. TOP‐NT established a consensus analysis code guiding unbiased detection of image‐based pathology using spatially co‐registered sham‐population z‐score standardization. Behavioral CDEs were constructed upon existing preclinical elements including neuroseverity score, rotor‐rod, Barnes, elevated‐plus, and Y‐maze. Biomarkers are measured by ELISA in rat serum and brain tissue homogenates and by densitometric histopathology for GFAP, aldolase C, Iba1, neurofilament light, tau, and phospho‐tau, alongside nuclear density and myelin amounts. A new morphometry approach was established across labs for accurate registration of injury‐distance and anatomical regions providing sham‐standardized metrics of cortical gray, white matter, and hippocampal biomarker changes. Relating TOP‐NT neuroimaging and fluid biomarkers to behavioral outcomes and histopathology will help understand TBI mechanisms and reveal TBI subtypes informing on ‘contexts of use’ for translatable tools. TOP‐NT datasets are curated using the open‐data‐commons repository for analytics and multidimensional associations (Ferguson, link‐abstract‐##; Radabaugh, link‐abstract‐##). TOP‐NT CDEs can help advance preclinical TBI reproducibility across laboratories and accelerate the efficacy of multi‐center trials.
Keywords: Biomarker, Imaging, Computational/Modeling, Neuropathology
WHAT'S SEX GOT TO DO WITH IT? IMPACT OF SHAM PROCEDURES, TRAUMATIC BRAIN INJURY ON CHRONIC GUT MICROBIOTA DYSBIOSIS, AND AFFECTIVE BEHAVIORS
1University of Arizona College of Medicine, Child Health, Phoenix AZ, United States, 2BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix AZ, United States, 3University of Arizona College of Medicine, Basic Medical Sciences, Phoenix AZ, United States, 4University of Arizona College of Medicine, Obstetrics and Gynecology, Phoenix AZ, United States, 5Phoenix VA Health Care System, Phoenix AZ, United States
Traumatic brain injury (TBI)‐induced enduring shifts in the gut microbiota are implicated in manifesting persisting affective symptoms (PASs). Clinical reports indicate TBI‐induced PASs are greater in women. Sex can influence microbiota diversity; however, the effect of sex, TBI, and time post‐injury on shifts in microbial milieu and the association with PASs have not been evaluated. Evaluation of microbial shifts with detailed comparison‐classification analyses provides for detection and identification of relevant microbial features that could be useful to predict outcomes. We hypothesize that sex‐specific TBI‐induced longitudinal microbiota dysbiosis can predict persisting affective‐like symptoms. Young adult, male and female Sprague‐Dawley rats (n = 9‐13/group) were randomized into midline fluid percussion or sham groups. Fecal pellets collected at baseline, 1, and 28‐days post‐injury (DPI), and anxiety‐like behaviors were assessed. Clustering and comparative analyses were performed to identify differential and predictive taxa using MicrobiomeAnalyst. Open‐field testing indicated anxiety‐like behavior in both sexes (p < 0.05). Clustering analyses of all detected microbes across all samples showed that grouping is dependent on injury, sex, and time‐post‐injury. LEfSe and Random Forest analysis identified these microbes responsible for differences: male shams: Ruminococcus at 28d post‐surgery; male TBI: Lactobacillus at 1DPI and Clostridium at 28DPI; female TBI: Ruminococcaceae UCG‐003 at 1DPI. Sham procedures increased the abundance of Ruminococcaceae UCG_014 and Lachnospiraceae NK4A136 (p < 0.001) in females and Ruminococcus in males (p < 0.001). TBI‐responsive microbiota composition was altered based on sex, acutely and chronically. These data indicate sex‐specific shifts in microbiota that may partly be responsible for anxiety‐like behavior with implications for sex‐dependent therapy.
Keywords: Biomarker, Behavioral Function, Gene Expression, Therapeutics/Drug Discovery, Informatics
DECONSTRUCTING THE BLOOD BRAIN BARRIER: EVALUATION OF CORTICAL ASTROCYTIC CHANGES SURROUNDING MICROVASCULATURE POST‐TBI
1Department of Child Health, College of Medicine‐Phoenix, University of Arizona, Phoenix AZ, USA, 2BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix AZ, USA , 3Phoenix VA Healthcare System, Phoenix AZ, USA, 4Arizona State University, Tempe AZ, United States, 5Midwestern University, Glendale AZ, USA
Diffuse traumatic brain injury (TBI)‐induced astrogliosis is implicated in long‐term post‐TBI recovery and morbidity, where blood‐brain barrier (BBB) permeability is specifically implicated as an increased risk for neurodegenerative diseases. Post‐TBI astrogliosis influences neuroprotection, neurorepair, neuropathology and BBB permeability; however, few studies have evaluated the temporal pathology as a function of aging‐with‐injury and sex‐dependence, including morphological evaluation around cerebrovasculature. Male and female late‐adolescent Sprague Dawley rats (n = 5‐6/group; total = 64) were subjected to sham surgery or midline fluid percussion injury (FPI). At 7‐, 56‐, and 168‐days post‐injury (DPI), brains were processed for immunohistochemical analyses to evaluate GFAP+ staining intensity in cortex without large vessels and a skeleton analysis and neuronal tracing of astrocyte branch projections around cortical penetrating arterioles using 40x and 100x brightfield microscopy, respectively. Cortical GFAP intensity changes as a function of FPI (p > 0.0001), DPI (p < 0.0001), and FPIxDPI (p < 0.0001); where FPI‐induced astrogliosis was greatest at 7DPI and declined over time (p < 0.001) and age‐related astrogliosis increased overtime (p < 0.05). SexxFPI approached significance (p = 0.07), with interactions occurring at 168DPI. An interim analysis indicates astrocyte branching increased near penetrating arterioles at 7DPI compared to shams (p < 0.05), appearing to form additional end feet that were no longer present at 168DPI. These data show different temporal profiles of astrogliosis as a function of aging and aging‐with‐injury, where distinct morphological changes around cerebrovasculature at acute time points are indicative of injury‐induced functional or structural mechanisms mediating post‐TBI cerebrovascular homeostasis, warranting further investigation as to whether changes are protective or pathological.
Keywords: Astrocyte, Aging, Blood Brain Barrier, Axonal Injury, Concussion/mTBI
POLARIZED SPLENIC MACROPHAGES AND SPINAL CORD INJURY REPAIR: THE SECRETOME EFFECT
Jose Lentilhas‐Graça1, Joao Afonso1, Diogo Santos1, Andreia Pinho1, Rui Lima1, Nidia Sousa1, Jorge Cibrao1, Tiffany Pinto1, Susana Monteiro1, Antonio Salgado1,
1Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
After injury the spinal cord is infiltrated by macrophages originated from splenic monocyte reservoir. Recently, the splenic monocyte reservoir was characterized as a major source of pro‐inflammatory subtype (M1). Herein, we aim to characterized alternative (M2a and M2c) and classic polarized splenic macrophages in vitro and understand how the molecules secreted by different subtypes influence spinal cord repair and functional recovery in vivo. Monocytes were isolated from the spleen of adult mice and were then polarized into M2a, M2c and M1 subtypes. The effect of each phenotype on axonal growth was studied using dorsal root ganglia (DRGs) explants. DRGs co‐cultured with M2a and M2c macrophages had further maximum distances reached by the axons and higher axonal arborization than those co‐cultured with M1, presenting significant differences. For the in vivo studies, the secretome of M1, M2a and M2c was collected and systemically injected into a mice SCI model. Results shown that only the animals injected with the secretome derived from M2c cells were able to significantly recovery their locomotor and autonomic functions. Interestingly, the pro‐inflammatory secretome (M1) appear to be beneficial in the acute phase, however, the positive effect stops after 3 weeks of administration. Histological analysis revealed that M2c‐treated mice have more ramified microglia and less astrogliosis. In conclusion, our data revealed that this relevant poll of macrophages can be polarized into pro‐regenerative phenotypes and that their secretome have a therapeutic effect on SCI mice.
Keywords: Neuroprotection, Therapeutics/Drug Discovery, Inflammation/Immune Function, Growth Factors/Cytokines
HEMOSTATIC MANAGEMENT PRIOR TO THE PLACEMENT OF INTRACRANIAL DEVICES IN PEDIATRIC TRAUMATIC BRAIN INJURY PATIENTS
1Penn State College Of Medicine, Hershey PA, United States, 2Penn State Department of Pediatrics, Hershey PA, United States, 3Penn State Department of Neurosurgery, Hershey PA, United States
Pediatric patients with traumatic brain injuries (TBI) often experience derangements in hemostasis that may lead to a delay in treatment, especially as it pertains to intracranial pressure (ICP) monitoring and placement of external ventricular drains (EVD). This study examines the clinical management of hemostatic correction prior to the placement of intracranial devices, the impact on the time to treatment and resulting complications in pediatric patients with TBIs.
This is a retrospective review of 49 pediatric TBI patients who required EVD or ICP monitoring at a level 1 pediatric trauma center from 2006‐2021. PT/INR, PTT, and platelet count prior to device placement were recorded. A timeline of clinical monitoring results from presentation to device placement was constructed. Complications from transfusion or device placement were recorded.
Seventeen patients had an abnormal PT/INR (≥1.6), PTT (>35 seconds), or platelet count (<100,000) in the first 24hrs. Twelve patients received fresh frozen plasma, and 4 patients received platelets prior to device placement. Transfused patients had a mean time from presentation to device placement of 8hr and 22min versus 4hr and 49min for non‐transfused patients. There were no complications recorded from transfusion or device placement, including in 4 patients with an INR ≥1.6 and 1 patient with platelets <100,000 immediately prior to placement.
Correction of abnormal hemostatic parameters delays placement of intracranial devices in pediatric TBI patients. There were no procedural or transfusion‐related complications in our cohort, even when abnormal hemostatic laboratory values were not corrected prior to device placement. Overall prognosis was not measured.
Keywords: Pediatric, Monitoring, Hemorrhage, Intracranial Pressure, Neurocritical Care
UNDERSTANDING SUBSTANCE USE DISORDER AMONG VETERANS WITH AND WITHOUT TRAUMATIC BRAIN INJURY: MERITS OF THE MULTITUDINOUS SELF MODEL
1Department of Psychology, University of Texas at San Antonio , San Antonio TX, United States, 2Polytrauma Rehabilitation Center, South Texas Veterans Health Care System , San Antonio TX, United States, 3Medical Humanities Program, The University of Texas at San Antonio, San Antonio TX, United States , 4Information, Decision‐Enhancement and Analytic Sciences Center, VA Health Care System , Salt Lake City UT, United States , 5Department of Internal Medicine, University of Utah , Salt Lake City UT, United States
Keywords: Rehabilitation, Behavioral Function, Concussion/mTBI
DUAL VULNERABILITY OF DENDRITIC PROTEIN MAP2 TO CALPAIN VS. CASPASE‐3 PROTEOLYSIS DURING EXPERIMENTAL AND CLINICAL NEURAL INJURY PARADIGMS: IMPLICATIONS FOR CLINICAL BIOMARKER
1University Of Florida, Gainesville GA, United States
Traumatic brain injury (TBI) is one of the major causes of mortality and morbidity worldwide. TBI represents a major diagnostic and therapeutic challenge where is an unmet need to identify brain‐specific markers indicating the pathophysiological characteristics of TBI. Recently, microtubule associate protein‐2 (MAP2) has shown to be a promising dendritic‐specific marker for TBI. In this study, we investigated the degradation pattern of MAP2, mediated by calpain‐ and caspase‐3, via utilizing different experimental models of in vitro and in vivo approaches and validating them with clinical samples. Biocemical analysis showed differential significant fragmentation patterns of caspase‐mediated breakdown product (BDP) of 130 kDa and 4 four calpain‐mediated BDPs (250, 110, 80, and 30 kDa). Furthermore, the degradation pattern of MAP2 was explored in vivo in a rat TBI model. This revealed that MAP2a/2b protein exhibits a specific BDP molecular signature where calpain‐ and caspase‐3 are involved in TBI‐associated proteolysis in a timely fashion. Furthermore, we translated the experimental findings of MAP2a/2b into human clinical settings characterizing the utility of MAP2a/2b to differentiate TBI patients from controls as evaluated in two independent clinical cohorts. Of interest, this study showed a correlation between CSF MAP2 concentrations and the occurrence of intracranial hypertension, a common secondary brain insult in diffused brain injury, where these patients displayed higher CSF MAP2 concentrations compared to controls. Taken together, our collective findings provide strong evidence supporting the utility of MAP2a/2b protein and its associated specific BDPs as brain injury‐specific dendritic biomarker that can be translated to clinical settings.
Keywords: Biomarker, Neurodegeneration, Axonal Injury
INCREASED NEUROINFLAMMATION IN SPECIAL OPERATORS WITH A HISTORY OF BLAST OVERPRESSURE EXPOSURE
1University Of Virginia School of Medicine, Charlottesville VA, United States, 2Johns Hopkins University School of Nursing, Baltimore MD, United States, 3University of Utah School of Medicine, Salt Lake City UT, United States, 4US Special Operations Command, Tampa FL, United States, 5Naval Medical Research Center, Silver Spring MD, United States
Exposure to blast overpressure has been a pervasive feature of combat‐related injuries. Studies exploring the neurological correlates of repetitive low‐level blast exposure in career Breachers demonstrated higher levels of tumor necrosis factor alpha (TNFα) and interleukin 6 (IL‐6) and decreases in interleukin‐10 (IL‐10) within brain‐derived exosomes (BDEs). The current study was initiated in partnership with US Special Operations Command (USSOCOM) to explore whether neuroinflammation is seen within special operators with prior blast exposure. Data was analyzed from 9 blast‐exposed special operators and 9 controls matched by age and duration of service. Neuroinflammation was assessed utilizing PET imaging of [18F]DPA‐714. Serum was acquired to assess inflammatory biomarkers within whole serum and BDEs. The Blast Exposure Threshold Survey (BETS) was acquired to determine blast history and self‐report and neurocognitive measures were acquired. Similarity‐driven Multi‐view Linear Reconstruction (SiMLR) was used for joint analysis of acquired data. Analysis of BDEs indicated significantly higher levels of TNFα within the exposed group. SiMLR‐based analyses of neuroimaging demonstrated strong relationships between GBEV, PET‐neuroinflammation, and cortical volume loss within highly blast‐exposed special operators. Affected areas included the anterior cingulate, anterior insula, superior temporal gyrus, and lingual gyrus. Post‐hoc assessments of cognitive measures failed to demonstrate significant associations with PET and cortical thickness values. This emerging evidence suggests neuroinflammation may be a key feature of the brain response to blast exposure over a career in operational personnel. The common thread of neuroinflammation observed in blast‐exposed populations requires further study.
Keywords: Biomarker, Blast, Imaging, Inflammation/Immune Function
NANOPARTICLE‐ER STRESS INHIBITOR CONJUGATES AMELIORATE ER STRESS AND NEUROINFLAMMATION IN A MOUSE MODEL OF PEDIATRIC TRAUMATIC BRAIN INJURY
Tejas Athavale1, Dhuha Al‐Rasool1, Mauda Abdullah1, Hassan El Ghoul1, Dr. Krisanu Bandyopadhyay1,
1University Of Michigan ‐Dearborn, Dearborn MI, United States
Traumatic brain injury (TBI) can trigger endoplasmic reticulum (ER) stress, which activates unfolded protein response (UPR) to restore ER homeostasis. However, prolonged ER stress can activate inflammatory and apoptotic pathways and exacerbate neurotoxicity and cell death. The objective of this study is to evaluate the therapeutic efficacy of nanoparticle‐ER stress inhibitor conjugates (nano‐ERi) on ER stress and inflammatory responses in a mouse model of pediatric TBI. Mice (males) from the same litter were randomized into 7 subgroups on postnatal day 20‐21: sham, TBI+saline, TBI+nano‐ERi (low dose), TBI+ nano‐ERi (medium dose), TBI+ nano‐ERi (high dose), TBI+nanoparticle alone, and TBI+ERi alone. Neurobehavioral tests were performed before injury (baseline) and at 24 hours post‐injury. The drugs (or same amount of saline) were administered intraperitoneally at 4‐6 hours post‐injury. Animals were euthanized at 24‐hour post‐treatment. The brains were collected for the evaluation of ER stress and inflammatory markers at the site of injury. We found that nano‐ERi conjugates 1) significantly inhibited ER stress pathways, indicated by decreased expression of ER stress markers; 2) significantly ameliorated neuroinflammation, indicated by decreased expression of pro‐inflammatory cytokines, and 3) significantly improved motor function and sensorimotor coordination at 1 day post‐injury, in comparison with TBI+saline, TBI+ERi alone and TBI+nanoparticle‐alone groups. In conclusion, nano‐ERi conjugates exhibit promising efficacy in decreasing ER stress and improving functionality after pediatric TBI. Future studies will focus on long‐term efficacy of nano‐ERi conjugates and explore the therapeutic time window as well as gender differences.
Keywords: Pediatric, Neuroprotection, Therapeutics/Drug Discovery, Inflammation/Immune Function
SLEEP FRAGMENTATION ENGAGES STRESS CIRCUITRY, ENHANCES INFLAMMATION, AND COMPROMISES HIPPOCAMPAL FUNCTION FOLLOWING TRAUMATIC BRAIN INJURY
1Department of Neuroscience, College of Medicine, The Ohio State University, Columbus OH, United States, 2Institute for Behavioral Medicine Research, Neurological Institute, The Ohio State University, Columbus OH, United States, 3Division of Biosciences, College of Dentistry, The Ohio State University, Columbus OH, United States
Traumatic brain injury (TBI) impairs the ability to restore homeostasis in response to stress, indicating hypothalamic‐pituitary‐adrenal (HPA)‐axis dysfunction. Many stressors result in sleep disturbances, thus mechanical sleep fragmentation (SF) provides a physiologically relevant approach to study the effects of stress after injury. We hypothesize SF stress engages the dysregulated HPA‐axis after TBI to exacerbate post‐injury neuroinflammation and compromise recovery. To test this hypothesis, male and female mice were given moderate lateral fluid percussion TBI or sham‐injury and left undisturbed or exposed to daily, transient SF for 30‐days post‐injury (DPI). Post‐TBI SF enhances cortical microgliosis and increases expression of pro‐inflammatory glial signaling genes characterized by persistent inhibition of the NR3C1 upstream regulator, which encodes glucocorticoid receptor (GR). Within the hippocampus, post‐TBI SF exaggerates microgliosis and decreases CA1 neuronal activity. Downstream of the hippocampus, post‐injury SF suppresses neuronal activity in the hypothalamic paraventricular nucleus, indicating decreased HPA‐axis reactivity. Direct application of GR agonist, dexamethasone, to the CA1 30 DPI increased GR activity in TBI SF mice but not Sham SF mice. This indicates altered GR sensitivity to agonism with post‐TBI SF, which could influence GR‐mediated HPA‐axis feedback inhibition. Electrophysiological assessment reveals TBI and SF induces deficits in Schaffer collateral long‐term potentiation associated with impaired acquisition of trace fear conditioning, reflecting dorsal hippocampal‐dependent cognitive deficits. Together these data demonstrate that post‐TBI SF engages the dysfunctional post‐injury HPA‐axis, enhances inflammation, and compromises hippocampal function. Therefore, external stressors that disrupt sleep have an integral role in mediating outcome after brain injury.
Keywords: Sleep, Behavioral Function, Secondary Injury, Microglia, Cognition/Learning/Memory, Gene Expression, Electrophysiology, Inflammation/Immune Function
REPETITIVE MILD TRAUMATIC BRAIN INJURY PROMOTES INFLAMMATION AND DISRUPTS FUNCTIONAL CONNECTIVITY IN THALAMIC NUCLEI
1University of Florida, Gainesville GA, United States
A major challenge in the field of head injury research is identification of the mechanisms driving brain dysfunction following traumatic brain injury (TBI). This is partly due to the wide variety of post‐injury manifestations in patients. We measured functional connectivity (FC) and expression of neuropathological markers after repetitive mild traumatic brain injury (rmTBI). C57Bl6 mice (∼2.5mo) sustained two rmTBI (0.6 J impacts 24 h apart) using the CHIMERA model or sham procedures. At 5 days post‐injury (dpi), changes in FC were assessed using resting state functional MRI (rsfMRI). We measured changes in gliosis and expression of disease‐associated neuropathological markers in grey and white matter (WM) regions using immunohistochemistry and nanoString‐GeoMx spatial profiling. Injured mice showed WM gliosis in the optic tract and corpus callosum. The rsfMRI data revealed aberrant node strength signatures in the mediodorsal and paracentral thalamus nuclei. In addition, the node clustering coefficient and eigenvector centrality in specific brain regions that processes visual, auditory, and somatosensory information also showed significant alterations. Phospho‐tau (S199) levels and expression of glial markers such Aldh1L1, GFAP, cathepsin‐D, and Iba‐1 were significantly increased in the optic tract. Moreover, the neuroinflammatory marker GPNMB was significantly increased in the thalamus of rmTBI mice. Our data suggest that besides chronic WM damage, rmTBI significantly alters brain functional connectivity and causes a profound inflammatory response in gray matter regions, including the thalamus. Given that the thalamus integrates a wide variety of signaling inputs, alterations to this structure could explain the variability of clinical outcomes following rmTBI.
Keywords: Astrocyte, Microglia, Axonal Injury, Concussion/mTBI, Inflammation/Immune Function, White Matter
EXPLOITING THE BIOLOGIC ABILITY OF CARBON DIOXIDE TO MANIPULATE CEREBRAL BLOOD FLOW IN ORDER TO PREVENT MILD TRAUMATIC BRAIN INJURY
1University of Cincinnati, James L. Winkle College of Pharmacy, Division of Pharmaceutical Sciences, Cincinnati OH, USA, 2University of Cincinnati, College of Arts and Sciences, Division of Neuroscience, Cincinnati OH, USA, 3Delta Chase LLC, West Chester PA, USA
Keywords: Neuroprotection, Concussion/mTBI, Therapeutics/Drug Discovery, Cerebral Blood Flow
SEX AS A BIOLOGICAL VARIABLE IN THE ACUTE VASCULAR AND BEHAVIORAL RESPONSE FOLLOWING MILD BLAST TRAUMATIC BRAIN INJURY
1Lexington VA Healthcare System, Lexington KY, United States, 2University of Kentucky, Lexington KY, United States
Low‐level blast exposure can result in neurological impairment for military personnel. Currently, there is a lack of experimental data using sex as a biological variable in neurovascular outcomes following blast exposure. To model mild blast traumatic brain injury (mbTBI), male and female rats (N = 6/group) were exposed to a single 11psi static peak overpressure blast wave using the McMillan blast device and cohorts were then euthanized at 6h, 24h, 7d, and 14d post‐blast followed by isolation of the amygdala. At 7d post‐mbTBI, male mbTBI group displayed significantly higher levels of anxiety‐like behavior (open field and elevated plus maze) compared to male sham at 7d post‐mbTBI; however, there were no differences in levels of anxiety behaviors in female groups. Blast‐induced neurovascular damage was explored by measuring expression of tight junction (TJ) proteins (zonula occludens‐1 (ZO1), occludin and claudin‐5), glial fibrillary acidic protein (GFAP) and astrocyte end‐feet coverage around the blood‐brain barrier (BBB). Western blot analysis demonstrates that TJ protein levels were significantly decreased at 6h and 24h post‐mbTBI in male rats, but not in female rats, compared to sham. Males showed decreased GFAP expression at 6h and 24h post‐mbTBI, whereas females decreased only at 6h post‐mbTBI. At 24h post‐mbTBI, astrocytic end‐feet coverage around BBB was significantly decreased in males following mbTBI. By 7d post‐mbTBI, there were no significant differences in TJ or GFAP levels between groups in either sex. Our findings also demonstrate sex differences in acute vascular and behavioral outcomes after single mbTBI.
Keywords: Blast, Post‐Traumatic Stress, Blood Brain Barrier, Vascular
NA+/H+ EXCHANGER IN INFLAMMATORY ACTIVATION OF MICROGLIA/MYELOID CELLS AND TRAUMATIC BRAIN INJURY OUTCOMES
1Department of Neurology, University of Pittsburgh, Pittsburgh PA, United States, 2Pittsburgh Institute for Neurodegenerative Disorders, University of Pittsburgh, Pittsburgh PA, United States, 3Department of Neurological Surgery, University of Pittsburgh, Pittsburgh PA, United States, 4Veterans Affairs Pittsburgh Health Care System, Pittsburgh PA, United States
Microglial inflammatory responses play an important role in neuroinflammation after traumatic brain injury (TBI). Here, we investigated the roles of a microglial pH regulatory protein Na+/H+ exchanger (NHE1) in TBI using Cx3cr1‐CreERT2 control (Ctrl) mice and selective microglial Nhe1 knockout (Cx3cr1‐CreERT2;Nhe1flox/flox, Nhe1 cKO) mice. Compared to Ctrl mice, Nhe1 cKO mice exhibited improved white matter myelination and neurological function recovery at 1‐30 days post‐TBI in a controlled cortical impact‐induced murine TBI model. To evaluate microglial proinflammatory activation in these mice, profiles of microglia/myeloid cells were analyzed by flow cytometry at 3‐day post‐TBI. No differences in the percentage of microglia (CD11b+CD45lo) and infiltrated myeloid cells (CD11b+CD45hi) were detected in contralateral (CL) or ipsilateral (IL) hemispheres of the Ctrl and Nhe1 cKO mice. However, the percentage of anti‐inflammatory CD206 and Ym‐1‐positive microglia was increased in the IL hemisphere of the cKO mice by 3‐fold and 7‐fold, respectively, compared to Ctrl mice. Similarly, the percentage of CD206 and Ym‐1‐positive myeloid cells was elevated in the cKO brains by ∼2.5‐fold. Additionally, post‐TBI administration of selective NHE1 inhibitor HOE642 stimulated Ym‐1‐positive myeloid cell profile. RNA sequencing of CD11b+ microglia/myeloid cells identified 233 genes differentially expressed between Ctrl and cKO brains, in which the cKO microglia showed significantly decreased expression of inflammatory genes. Taken together, these findings demonstrate that selective deletion of microglial Nhe1 gene promotes the restorative activation of microglia/myeloid cells after TBI and that microglial Nhe1 plays important roles in neuroinflammation and TBI‐induced demyelination and neurological function deficits.
Supported by VA awards; I01BX004625, IK6BX005647.
Keywords: Microglia, Gene Expression, Inflammation/Immune Function, White Matter
BAD BLOOD: BLOOD SERUM TRANSFUSION FROM ANIMALS THAT RECEIVED PAIN INPUT FUELS SECONDARY INJURY
1Texas A&M University, College Station TX, United States
Spinal cord injury (SCI) involves both the primary insult to the spinal cord and the progressive secondary damage that occurs after the initial injury. Our laboratory has found that nociceptive stimulation applied caudal to the lesion site can further worsen this secondary injury by expanding the area of hemorrhage and increasing inflammation. The present experiment provides evidence that pain‐induced exacerbation in secondary injury is not a strictly local process. In the preliminary phase of this experiment, 8 rats received a moderate spinal contusion injury. The next day four of the rats received pain input in the form of electrical stimulation delivered to the tail. The other four rats received an equal period of restraint (no shock). All animals were then sacrificed, and their blood was collected and spun into serum. In the next phase of the experiment, the blood serum for each group (shock, no shock) was equally pooled and 16 rats received a moderate spinal contusion injury. The next day, these rats were given a 0.3mL intravenous transfusion of the serum either from the pain‐input or the no pain‐input rats. Rats that received serum from pain‐input animals had increased hemorrhage and pro‐inflammatory cytokines at the lesion site. Rats that received serum from pain‐input rats also had a decrease in spleen weight and a decrease in locomotor function. Future studies aim to examine the components of the blood serum that are involved in driving these effects.
Keywords: Secondary Injury, Hemorrhage, Pain, Inflammation/Immune Function
UNEXPECTED ANTI‐INFLAMMATORY CHANGES FOLLOWING LOW‐LEVEL REPETITIVE HEAD IMPACTS
1Division of Emergency Medicine, Boston Children's Hospital, Boston MA, United States, 2Department of Pediatrics, Harvard Medical School, Boston MA, United States, 3Department of Kinesiology, Indiana University, Bloomington IN, United States, 4Department of Emergency Medicine, University of Rochester School of Medicine and Dentistry, Rochester NY, United States, 5Division of Sports Medicine, Boston Children's Hospital, Boston MA, United States, 6The Micheli Center for Sports Injury Prevention, Waltham MA, United States
Recently, there has been increased attention in the scientific community to the phenomenon of sub‐concussive impacts, those hits to the head that do not cause the signs and symptoms of a concussion. Some suggest that repeated sub‐concussive impacts may alter behavior and cognition, but the mechanisms underlying these changes are not well‐defined. Here, we adapt our weight drop model of repetitive mild traumatic brain injury in an attempt to produce a model of low‐level repetitive head impacts (RHIs). To understand the effects of a single cluster of RHIs, as well as the effect of an increased impact frequency within the cluster, we evaluated behavioral measures, serum biomarkers, cortical protein quantification, and immunohistochemistry both acutely and sub‐acutely. In the absence of statistically significant differences in performance on rotarod, open field test, elevated plus maze, and Morris water maze, the impact protocol did generate dose‐dependent changes in brain pathology. Evaluation of serum biomarkers revealed limited changes in GFAP and NF‐L, which suggests that their diagnostic utility may not emerge until the exposure reaches a certain threshold. Robust decreases in both IL‐1β and IL‐6 were observed in the serum and the cortex, indicating downregulation of inflammatory pathways. Additional exploratory analyses revealed similar changes in serum CXCL1, IL‐22, IL‐23, IL‐27, and CCL7. These experiments yield initial data on pathology and biomarkers in a mouse model of low‐level RHIs, providing a starting point for further exploration of the potential role of anti‐inflammatory processes in outcomes, and how these markers may evolve with repeated exposure.
Keywords: Biomarker, Concussion/mTBI, Inflammation/Immune Function
PENTOBARBITAL ANESTHESIA ATTENUATES PAIN INDUCED HEMORRHAGE AFTER TRAUMATIC BRAIN INJURY (TBI)
1Texas A&M University, College Station TX, United States
Traumatic brain injury (TBI) is often accompanied by polytrauma. This tissue damage provides a source of nociceptive input that increases the extent of hemorrhage. The present study links the adverse effects of nociceptive stimulation to an increase in blood brain barrier (BBB) permeability and shows that inducing and anesthetic state blocks pain‐induced hemorrhage. Male Sprague‐Dawley rats received a moderate unilateral injury to the right frontal region. 24 hours later, rats received an injection of capsaicin or vehicle to the contralateral hindpaw. In Exp. 1, rats received a systematic injection of Evans Blue dye (2.5 mL i.p.) immediately following pain stimulation to assess BBB permeability. Rats were sacrificed at three hours, perfused with saline, and brain tissue was flash frozen. Evans Blue infiltration was assessed using nanodrop spectrometry. Only animals who received capsaicin displayed increased concentrations of Evans Blue dye on the injured side compared to the contralateral (p < .05). Exp. 2 examined whether pretreatment with pentobarbital attenuates pain induced hemorrhage. Rats received a systematic injection of pentobarbital (35 mg/kg i.p.) or its vehicle thirty minutes prior to pain simulation to induce an anesthetic state. At three hours, rats were sacrificed, perfused with saline, then 4% PFA. Brain tissue was cryoprotected, sectioned, and stained with hematoxylin and eosin. Vehicle treated capsaicin rats displayed increased hemorrhage compared to pentobarbital treated capsaicin rats (p < .05). Future studies are examining mechanisms by which pain fuels hemorrhage after TBI.
Keywords: Neuroprotection, Secondary Injury, Blood Brain Barrier, Hemorrhage, Pain
PROPRIOCEPTIVE GATING OF NOCICEPTIVE SIGNALING: POSITIONING TO MINIMIZE MALADAPTIVE PLASTICITY AFTER SPINAL CORD INJURY.
1Texas A&M, College Station TX, United States, 2McGovern Medical School, Houston TX, United States
Prior studies have shown that neurons within the spinal cord can support instrumental learning and that this adaptive plasticity can be interrupted by nociceptive input. Rats undergo a thoracic (T2) transection and are subsequently tested. Over time, rats shocked whenever the leg is extended (controllable stimulation) learn to maintain the stimulated leg in a flexed position that minimizes net shock exposure. This capacity to learn is prohibited by as little as 6 minutes of uncontrollable shock. To identify ways to maximize adaptive plasticity while minimizing maladaptive impacts the present study assessed the role of proprioceptive signals. In experiment 1 rats received 6 minutes of uncontrollable shock to the hind limb while it was held in a flexed position or allowed to hang freely. Experiment 2 mirrored experiment one using a more clinically relevant source of nociceptive input, capsaicin. Experiment 3 assessed whether the effects of proprioceptive signaling were dependent upon the stimulation occurring on the limb in question. 6 minutes of uncontrollable shock to the tail was administered while both hind limbs were held in a flexed position or allowed to hang freely. In all experiments animals were tested for spinal learning. Rats that were exposed to nociceptive stimulation while the hindlimbs were flexed were able to learn, whereas those that received pain input with the legs hanging freely expressed a learning deficit. These results suggest that proprioceptive signals gate the effects of nociceptive input after spinal cord injury (SCI) and suggest a non‐invasive therapeutic option.
Keywords: Neuroprotection, Behavioral Function, Cognition/Learning/Memory, Pain, Regeneration & Plasticity, Neuropathology
ALTERED WHITE MATTER STRUCTURE IN PIG BRAIN REVEALED BY EX VIVO DIFFUSION MRI AFTER CLOSED‐HEAD TRAUMATIC BRAIN INJURY
1University of Pennsylvania, Philadelphia PA, United States, 2University of Virginia, Charlottesville VA, United States
Diffusion‐weighted magnetic resonance imaging (DWI) provides rich information on white matter integrity, an important pathological feature of traumatic brain injury (TBI). A pig model was used to test whether the alteration of brain structure depicted by DWI could be used to better diagnose TBI. Twelve 6‐month‐old female Yucatan pigs, including 4 sham animals, were anesthetized and subjected to rapid sagittal head rotation to produce mild (n = 4) or moderate (n = 4) TBI. Fourteen days after injury, brains were removed after transcardial perfusion. DWI were acquired with a diffusion‐weighted spin‐echo sequence in a Bruker 9.4T scanner. An investigator‐blind study was carried out to process the imaging data following the standard analysis steps including pre‐processing of the data (eddy current correction), diffusion tensor reconstruction, atlas‐based regions of interest (ROI), and tractography. Mean diffusion measures (e.g., fractional anisotropy: FA) were calculated for the white matter ROIs. Structural connectivity based on the gray matter ROIs was also generated. Diffusion measures and the connectivity matrices (including subsequent graph measures) were used to cluster the subjects into different groups using a modularity algorithm. Preliminary results (n = 9) show groupings based on FA could distinguish injured from sham with an accuracy of 77.8%; groupings were less accurate in predicting injury severity (66.7%). Alternative network measures (modularity and eigenvector centrality) also correlated with injury status with an accuracy of 66.7%. These findings are first to calculate the accuracy of DWI‐based measures in predicting injury in a large animal TBI model, and provide more support for developing image‐based biomarkers for TBI.
Keywords: Biomarker, Imaging, Axonal Injury, White Matter
FORMOTEROL AMELIORATES THERMAL HYPERALGESIA AND IMPROVES LOCOMOTOR FUNCTION AFTER MODERATE SPINAL CORD INJURY
1University Of Arizona, Tucson AZ, United States, 2United States Department of Veterans Affairs, Tucson AZ, United States
In addition to loss of sensation and function below the injury site, neuropathic pain is a well‐documented and debilitating consequence of spinal cord injury (SCI). While the FDA‐approved β2‐adrenergic receptor agonist, formoterol, improves mitochondrial function and locomotor capability post‐SCI in mice, the effect of formoterol on pain after injury has yet to be determined. Female C57bl/6j mice were subjected to moderate SCI (60 kdyn) followed by daily treatment with vehicle or formoterol (0.3 mg/kg, i.p) beginning 8h after injury and continuing for 6 weeks. Formoterol treatment improved functional recovery in SCI mice compared to vehicle treatment by 7 DPI (BMS score 3 v 2), reaching a final BMS score of 5 v 4, at 6 weeks. All injured mice experienced a 20% weight loss by 3 DPI. Formoterol‐treated mice returned to pre‐surgery weight by 21 DPI, while body weight was not restored in vehicle‐treated mice. Nociceptive pain was assessed via thermal hyperalgesia using a Hargreaves Apparatus with an IR intensity of 50 and automatic cutoff of 20s. Withdrawal latency was measured prior to injury, then weekly beginning 21 DPI, at which point all injured mice displayed a BMS score of at least ∼4 and were able to respond to heat stimulation. Formoterol‐treated mice displayed increased withdrawal time compared to vehicle‐treated mice 21, 35 and 42 DPI. We suggest that formoterol treatment not only improves functional recovery post‐SCI, but also reduces thermal pain sensitivity, further supporting formoterol as a potential therapeutic option after SCI.
Keywords: Rehabilitation, Behavioral Function, Secondary Injury, Pain
INVENTION AND COMPARISON OF METHODS FOR AUTOSTOP AND STABILITY IN CRANIAL DRILLING
1Johns Hopkins University, Baltimore MD, United States, 2Hubly Surgical, Lisle IL, United States, 3Centura Health, Colorado Springs CO, United States, 4Northwestern Medicine, Chicago IL, United States
Patients with hydrocephalus, traumatic brain injury, intracranial hemorrhage, and ruptured aneurysm often undergo surgery performed outside the operating room. These emergency intracranial access procedures rely on a hand‐crank drill that allows for drilling beyond the skull into soft tissue and for unstable drilling, which can result in misaligned burr holes and subsequent catheter misplacement. Today's hand‐crank drill plunges an average 4.9mm per procedure, and an average three catheter placement attempts are made per procedure. Both can cause catastrophic damage to the patient. Thus, a portable cranial drilling system with increased stability and autostop is needed to improve patient safety in emergency intracranial access procedures. Several methods of producing stability and autostop within a portable cranial drilling system are user‐tested to determine the optimal solution for patient safety. Drill‐power, unique drill bit geometry, and tripod guide hub are tested for improved stability. Autostop methods tested include: interface ledge‐lock, lever‐lock, cam pin lock, over‐center linkage, conical interface collet, clutch (as employed in the operating room‐only cranial perforator), and current monitor. Methods were compared based on their efficacy in ideal environments, integration with procedure, ability to reset, likelihood for user error, flexibility for varying bone thickness and density, flexibility to drilling angle, durability in extreme environments (i.e. humidity, transit), and cost. These metrics determined the current‐monitor autostop and a combination of power, unique drill bit geometry, and a non‐tripod guide hub to be optimal for increasing patient safety in emergency intracranial access procedures when applied to a portable cranial drilling system.
Keywords: Cerebrospinal Fluid, Hemorrhage, Intracranial Pressure, Neurocritical Care
CONCUSSION IN CIVILIANS AND MILITARY SERVICE MEMBERS OCCURS IN THE TOP 1% OF HIGH‐ENERGY HEAD IMPACTS
1Prevent Biometrics, Chaska MN, United States
This paper summarizes new data aggregated from the past few years of a DoD‐funded project (W81XWH‐17‐1‐0019) aimed at accurately and precisely monitoring head impacts across a variety of military training and civilian sport activities.
A total of n = 57 ‘check engine’ impacts, when a subject had at least one visible concussion sign, were observed. Clinical information was available for 19 of these impacts, and all were concussions.
All of the ‘check engine’ impacts were in the top 1% by magnitude of PLA, Workload, or both.
Keywords: Blast, Concussion/mTBI, Chronic Traumatic Encephalopathy, Biomechanics
AGING WITH TRAUMATIC BRAIN INJURY: EVALUATION OF NEUROPATHOLOGY, AXONAL INJURY, NEUROINFLAMMATION, AUTOPHAGY, AND PTAU PATHOLOGY IN THE DENTATE GYRUS AT 6‐MONTHS POST‐INJURY
1Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix AZ, USA, 2University of Arizona College of Medicine‐Phoenix, Phoenix AZ, USA, 3Arizona State University, Tempe AZ, USA, 4Neuroscience Associates, Knoxville TN, USA, 5Phoenix VA Health Care System, Phoenix AZ, USA
Traumatic brain injury (TBI)‐induced Wallerian degeneration and secondary injury sequelae are associated with persisting neuroinflammation hypothesized to increase risk or early‐onset of neurodegenerative diseases. At 6‐months post‐midline fluid percussion injury (FPI), we evaluated markers of neuropathology (amino cupric‐silver stain), axonal injury (APP), neuroinflammation (Iba‐1; GFAP), autophagy (neutral red), and phospho‐tau (AT8) pathology in the dentate gyrus (DG) of the hippocampus in male and female Sprague Dawley rats (n = 5‐6/group). Positive silver stain was present in injured and age‐matched shams; however, the organization, localization, and amount of neuropathology were region‐dependent within the DG. After FPI, punctate pathology was predominantly found within the inner granule layer vs. sham, where punctate and neuronal pathology was predominant in the granule cell layer. Positive APP pathology was present in sham and injured white matter tracts. Microglia number, branch length/microglia, and endpoints/microglia were similar between groups, although visual assessment revealed non‐uniform presentation of activated morphologies indicative of a neuroinflammatory response. Evaluation of a time course of glial activation at 7‐, 56‐, and 168DPI indicated a timexinjury interaction (F(2,51) = 17.47;p<0.0001) where activation follows an independent and different time course in sham (p < 0.05) vs. injured (p < 0.05) DG. A 45% increase in neutral red staining was present in FPI compared to sham (p < 0.05). No AT8 staining was observed in the DG or other brain regions. No quantifiable sex differences were detected. Different distribution of neuropathology, glial activation time courses, and evidence of persistently activated autophagy pathways implicate novel differences between age‐ and aging‐with‐injury‐related neuropathological processes requiring further investigation.
Funding: NIH_R01NS100793_Phoenix_Children's_Hospital_Mission_Support.
Keywords: Biomarker, Neurodegeneration, Axonal Injury, Cell Death, Neuropathology
THE INTERACTION OF INSOMNIA AND DEPRESSIVE SYMPTOMS DURING RECOVERY FROM MTBI
1University of Texas at Austin, Austin TX, United States, 2University of California, Berkeley, Berkeley CA, United States, 3University of Washington, Seattle WA, United States, 4Medical College of Wisconsin, Milwaukee WI, United States
The purpose of this study was to characterize the trajectory and bidirectional relationships of insomnia and depressive symptomatology during the year following mTBI using data from TRACK‐TBI, a longitudinal cohort study of TBI and orthopedic controls (OTC). The Insomnia Severity Index (ISI), Patient Health Questionnaire 9 (PHQ‐9), and Brief Symptom Inventory 18 (BSI‐18) assessed insomnia and depressive symptoms at 2 weeks and 3, 6 and 12 months post‐injury. Participants with psychiatric or sleep disorder history were excluded, yielding 1557 mTBI (GCS 13‐15) and 226 OTC participants. Latent class growth analysis (LCGA) identified ISI trajectories. A random intercept cross‐lagged panel model (RI‐CLPM) tested the lagged effects of ISI, PHQ‐9 and BSI‐18 on each other. All measures were tightly correlated, with overall morbidity diminishing over 12 months. An LCGA 5‐group model showed 25% with persistent insomnia, 5% improving and 70% consistently below the ISI clinical cutoff. The RI‐CLPM (overall model fit: CFI = .99, TLI = .99, RMSEA = .04) confirmed that insomnia and depressive symptoms are worse for mTBI than for OTC. In addition to being longitudinally correlated (random intercept ϕ = .74, p < .001), depressive symptomatology operates as a leading indicator of worsening insomnia 3 to 6 months post‐injury (β = .27, p = .001). Patients with mTBI experience greater mental health and sleep difficulties than OTC, and worsening depressive symptoms may be an earlier contributor to worsening insomnia during the subacute period post mTBI.
Keywords: Sleep, Depression, Concussion/mTBI
HIGH AMYOTROPHIC LATERAL SCLEROSIS RISK, BUT TYPICAL AGE OF ONSET AMONG FORMER PROFESSIONAL SOCCER PLAYERS
1University of Glasgow, Institute of Neuroscience and Psychology, Glasgow, United Kingdom, 2University of Glasgow, Institute of Health and Wellbeing, Glasgow, United Kingdom, 3Hampden Sport Clinic, Hampden Park, Glasgow, United Kingdom, 4Department of Neuropathology, Queen Elizabeth University Hospital, Glasgow, United Kingdom
There is growing evidence that risk of a range of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS)/motor neuron disease, is high among former elite level contact sport athletes. However, wider understanding of the disease profile in former athletes, including age at diagnosis, remains poorly described. To address this, we compared data on ALS diagnoses among former professional soccer players to that of matched general population controls.
“Football's InfluencE on Lifelong health and Dementia risk: Later Outcomes and NeuroradioloGy” (FIELD:LONG) is a retrospective cohort study accessing comprehensive, electronic medical, prescribing, and death records for all Scottish former professional soccer players (FSP) born 1900 to 1990 (n = 11,995) and their sex, age, and social deprivation matched population controls (MPC; n = 35,952). Incident ALS diagnoses were identified from available datasets, and risk compared between populations.
Over a median follow up of 21.1 years, 34 (0.28%) FSP and 29 (0.08%) MPC were identified with ALS (hazard ratio 3.30; 95% confidence interval 1.96 to 5.56; p < 0.001). Age at earliest coding of ALS was equivalent among FSP (median 60; IQR 47‐73) and MPC (median 63; IQR 54‐70; Kruskal‐Wallis: 0.969).
This study adds to the growing body of evidence highlighting increased neurodegenerative disease risk in former contact sport athletes, and further shows no difference in age at onset of the disease in this at risk population.
Keywords: Neurodegeneration, Concussion/mTBI
HISTORY OF INTIMATE PARTNER VIOLENCE IS ASSOCIATED WITH ADVERSE MENTAL HEALTH OUTCOMES IN MID‐LIFE
1School of Neuroscience and Psychology, University Of Glasgow, Glasgow, UK, 2Department of Social Medicine, Ohio University, Athens, USA, 3Edinburgh Dementia Prevention, University of Edinburgh, Edinburgh, UK, 4Department of Psychiatry, University of Oxford, Oxford, UK, 5Institut des Neurosciences de Montpellier, Montpellier, France, 6Department of Neuropathology, Queen Elizabeth University Hospital, Glasgow, UK
There is growing awareness of the association between traumatic brain injury (TBI) and risk of neurodegenerative disease. Estimates indicate approximately 30% of women will experience intimate partner violence (IPV) in their lifetime, often with TBI exposure. Nevertheless, to date, studies on brain health outcomes following IPV are limited. To address this, we investigated the prevalence of IPV, TBI, and mental health outcomes in mid‐life within an observational cohort study.
PREVENT Dementia is a general population cohort study with participants recruited aged 40‐ 59 years for longitudinal measures of brain health. Participants with histories of domestic abuse were identified and compared with control participants in measures of lifetime symptomology of post‐traumatic stress disorder (Lifestressor checklist), TBI (Brain Injury Screening Questionnaire) and mental health outcomes (clinical interview; Spielberger State Anxiety Inventory; Centre for Epidemiologic Studies Depression Scale).
A history of domestic abuse was reported in 149/691 (22%) of PREVENT participants, 90 of whom report IPV. Among IPV exposed participants there was greater TBI exposure in multiple measures than among controls, including hospitalisations from concussion. Further, lifetime PTSD symptomology and clinical diagnoses of depression and anxiety disorders were higher in participants with history of IPV than in controls.
Our data confirm high TBI exposure among individuals with IPV history, while also demonstrating this population show higher rates of adverse mental health outcomes. This work underlines the prevalence of IPV and the necessity to consider TBI exposure and brain health outcomes among this population.
Supported by U54NS115322 and The Drake Foundation.
Keywords: Aging, Depression, Post‐Traumatic Stress, Concussion/mTBI
TRAUMATIC BRAIN INJURY RECAPITULATES DEVELOPMENTAL CHANGES OF AXONS
1University Of Pennsylvania, Philadelphia PA, United States, 2University of Missouri, Columbia SC, United States
During development, half of brain white matter axons are maintained for growth, while the remainder undergo developmental axon degeneration. After traumatic brain injury (TBI), injured axons also appear to follow pathways leading to either degeneration or repair. These observations raise the intriguing, but unexamined possibility that TBI recapitulates developmental axonal programs. Here, we examined axonal changes in the developing brain in young rats and after TBI in adult rat. Multiple new mechanisms were found in both development and TBI that regulate axonal microtubule (MT) stability through tubulin post‐translational modifications and the MT associated proteins (MAPs), tau and MAP6. Specifically, degenerating axons in both development and TBI underwent phosphorylation of tau and excessive tubulin tyrosination, suggesting MT instability and depolymerization. Conversely, nearby axons without degenerating morphologies, had increased MAP6 expression and maintenance of tubulin acetylation, suggesting enhanced MT stabilization, thereby supporting survival or repair. Quantitative proteomics further revealed similar signaling pathways of axon degeneration and growth/repair, including protein clusters and networks. This comparison approach demonstrates how focused evaluation of developmental processes may provide insight into pathways initiated by TBI. In particular, the data suggest that TBI may reawaken dormant axonal programs that direct axons towards either degeneration or growth/repair.
Keywords: Neurodegeneration, Axonal Injury, Concussion/mTBI, Informatics
TDP‐43 PROTEINOPATHY IN TRAUMATIC BRAIN INJURY RELATED NEURODEGENERATION (TREND): A CONNECT‐TBI STUDY
1University Of Pennsylvania, Philadelphia PA, United States, 2University of Glasgow, Glasgow, United Kingdom
Limited studies document abnormally phosphorylated transactive response DNA‐binding protein 43 (p‐TDP‐43) deposition in patients with traumatic brain injury related neurodegeneration (TReND), in particular, in association with chronic traumatic encephalopathy neuropathologic change (CTE‐NC). However, the prevalence and distribution of p‐TDP‐43 in CTE‐NC and its distinction from that seen in wider neurodegenerative disease (NDD) has not been formally assessed. Patients with history of exposure to repetitive mild traumatic brain injury and documented NDD (rmTBI; n = 30), together with age‐matched controls with no known TBI exposure, either with (n = 24) or without (n = 11) NDD, were identified within the CONNECT‐TBI archive. Whole slide digital images of standardized brain tissue sections stained for p‐TDP‐43 (1D3) were reviewed and the pattern and distribution of pathology mapped. Whilst no p‐TDP‐43 pathology was present in controls without NDD, the prevalence of p‐TDP‐43 pathology was similar in rmTBI patients (53%) and in age‐matched controls with NDD (50%; NS). However, whereas p‐TDP‐43 was typically localized (limbic‐predominant age‐related TDP‐43 encephalopathy [LATE] stage 1‐2) in controls with NDD and in rmTBI patients without CTE‐NC, in patients with CTE‐NC this pathology was more often widespread and advanced (LATE stage 3; p = 0.0357). These results demonstrate the relationship between rmTBI and TDP‐43 pathologies is perhaps more nuanced than previously understood. Further studies are required to characterize the association between TReND and TDP‐43 proteinopathy, meanwhile this work underlines the importance of robust study design in human neuropathology investigations, including comparison to appropriate controls.
Keywords: Neurodegeneration, Concussion/mTBI, Chronic Traumatic Encephalopathy, Neuropathology
NEUTROPHIL EXTRACELLULAR TRAPS IN SPINAL CORD INJURY
1Texas A&M University, College Station TX, United States
Neutrophils are the first peripheral immune cell to infiltrate the spinal cord in large numbers following injury; however, their role in secondary tissue damage is poorly understood. Neutrophil extracellular traps (NETs) are a neutrophil effector function wherein chromatin is decondensed, decorated with granule proteins, and expelled from the cell as a mechanism to trap and destroy pathogens. However, NETs have also been shown to be damaging to host tissues. The contribution of NETs to tissue damage in spinal cord injury (SCI) remains underexplored. To determine if NET formation occurs acutely after SCI, we performed an ELISA for citrullinated histone 3 (CitH3) and DNA complexes (indicative of NETs) in spinal cord samples at various acute time points after SCI and found that CitH3/DNA levels rapidly increased over the first 12 hours and peaked within the first 24 hours after injury. Similar capture ELISAs for complexes of DNA and granule enzyme (Myeloperoxidase (MPO) and Neutrophil Elastase (NE)) confirmed these data. We also verified NET formation in SCI via flow cytometry using neutrophils isolated from blood and spinal cord samples. At 24 hours post‐SCI, we observed a nearly 7‐fold increase in CitH3+/Ly6G+ cells in the injured spinal cord relative to the blood, confirming that NET formation occurs in the spinal cord post‐SCI. Finally, colocalization of NET markers (CitH3, MPO, and NE) with neutrophil markers (Ly6G) in tissue sections further confirmed NET formation in vivo following SCI. Collectively, our data demonstrate the first evidence of NETs in the injured murine spinal cord.
Keywords: Behavioral Function, Secondary Injury, Inflammation/Immune Function
TRAUMATIC BRAIN INJURY INDUCES CHRONIC INFLAMMATORY, VISUAL AND SENSORY ALTERATIONS IN CONTROLLED‐CORTICAL IMPACT MICE MODEL
1Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta GA, United States, 2Department of Pathology, Medical College of Georgia, Augusta University, Augusta GA, United States, 3Department of Neurology, Medical College of Georgia, Augusta University, Augusta GA, United States, 4Georgia Cancer Center, Augusta GA, United States, 5Oral Biology and diagnostic Sciences, Dental College of Georgia at Augusta University, Augusta GA, United States
Traumatic brain injury (TBI) is the acquired brain injury due to a single or multiple blow(s) to the head. While severe TBI is an immediate risk to life, secondary long‐term effects are not yet fully discovered. Clinical studies highlight the potential risk of developing neurodegenerative disorders post‐TBI, however, the underlying drivers are unknown. Controlled‐cortical impact mice model has been extensively used to investigate acute and chronic effects of brain injury. Here, we hypothesized that cellular and molecular analysis of post‐TBI mice in the chronic phase could potentially reveal the long‐term risks of TBI‐induced neurodegeneration. Using NanoStringTM, we have analyzed gene signatures associated with neuropathology pathways in 1‐year post‐TBI mice. Magnetic resonance imaging was used to investigate anatomical, and functional changes in the brain, and field tests were used to investigate behavioral changes. 1‐year post‐TBI mice show white matter injury accompanied by increased necrotic volume, decreased cerebral blood flow, and restricted behavioral functions. Gene‐signature analysis revealed 77 differentially expressed genes associated with neuropathology, activated microglia, and astrocytes. Ontology analysis suggests that genes related to the visual system and sensory pathways were greatly impaired, which were further confirmed by the IHC of the retina and brain. We also found increased senescence in 1‐year post‐TBI mice. In conclusion, our results show that chronic inflammation post‐TBI represents a significant risk factor for neurodegenerative disorders and can also affect distinct organs other than the brain.
Keywords: Neurodegeneration, Gene Expression, Concussion/mTBI, Inflammation/Immune Function
AMNION CELL SECRETOME‐MEDIATED THERAPY INITIATED AT 24H POST EXPERIMENTAL BRAIN TRAUMA PROTECTS AGAINST TRAUMATIC OPTIC NEUROPATHY
1The Roskamp Institute, Sarasota FL, United States, 2James A. Haley Veterans Hospital, Tampa FL, United States, 3Noveome Biotherapeutics, Inc, Pittsburgh PA, United States, 4University of South Florida, Tampa FL, United States
Research sponsored by the Department of Veterans Affairs reported that as many as 75% of the Service members who sustained a traumatic brain injury had visual dysfunction. The proposed project explores the potential benefit of ST266 delivered by the intranasal route to treat TBI‐associated visual defects. ST266 is a proprietary secretome obtained by culturing a novel population of cells termed Amnion‐derived Multipotent Progenitor cells under proprietary, pharmaceutical grade GMP conditions provided by Noveome Inc. We tested a known therapeutic dose via intranasal delivery once or twice daily in male C57BL/6 mice using our r‐mTBI model. ST266 was delivered beginning 24h post last injury/sham anesthesia. ST266 improved learning and spatial memory when using the Barnes Maze starting at 10 days post last injury. The optomotor response frequency decreased with increasing cycles per degree and in response to injuries, but no treatment effect was observed. ST266 treatment significantly reduced the loss of retinal ganglion cells at 20 days post last injury compared to control. ST266 treatment also attenuated astrogliosis, microgliosis and leukocytes infiltration in the optic nerve and tract of the injured mice. Microgliosis and astrogliosis was also reduced after treatment with ST2666 in the dorsal lateral geniculate nucleus of the injured animals when compared to control. No injury or treatment effect was observed in the visual cortex in this preclinical model. The current results support non‐invasive, intranasal ST266 as a potential neuroprotective therapy for optic nerve injury as it reduces RGC loss, optic nerve neuroinflammation, and improves learning and spatial memory.
Keywords: Secondary Injury, Concussion/mTBI, Therapeutics/Drug Discovery, Regeneration & Plasticity, Inflammation/Immune Function, Neuropathology
CHARACTERIZATION OF HIPPOCAMPAL CA1 DENDRITIC SPINE DENSITY AND MORPHOLOGY AND GLUA1 EXPRESSION 2 WEEKS AFTER CONTROLLED CORTICAL IMPACT IN RATS
1Dept of Neurological Surgery, University of Pittsburgh, Pittsburgh PA, United States, 2VA Pittsburgh Healthcare System, Pittsburgh PA, United States
Extensive effort has been made to study the role of synaptic deficits in cognitive impairment after traumatic brain injury (TBI). The dendritic spine is a dynamic structure, which functions as the anatomical locus of synaptic plasticity and underlies learning and memory. This study examined the effect of controlled cortical impact (CCI) on hippocampal CA1 dendritic spine density and morphology, along with protein expression of hippocampal α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptor GluA1 sub‐unit, a protein integral to synaptic plasticity. Adult, male Sprague Dawley rats (275‐300g, 3 animals per group, 2‐3 neurons per animal) received either CCI (2.5mm deformation, 4m/s) or control/Sham surgery. 2 weeks post‐injury, brains were processed for Golgi staining, z‐stacks were imaged on a Nikon confocal microscope and spines were counted and classified using Neurolucida 360 software. No change in spine density was observed between groups. However, there was a significant decrease in the number of “mushroom” spines on apical dendrites and a trending decrease on basal dendrites after CCI compared to Sham (Student's t‐test, p = 0.0227, p = 0.0533, respectively). There was a trending decrease in number of “thin” spines on apical dendrites after CCI (p = 0.0533). Protein expression of GluA1 was measured by western blot in hippocampal synaptosomes. There was a significant decrease in GluA1 expression after CCI compared to Sham (p < 0.0001). In conclusion, CCI significantly alters CA1 dendritic spine morphology and GluA1 expression 2 weeks post‐injury, reflective of cognitive deficits previously observed at this time‐point. This metric may be used to evaluate future therapeutic studies targeting synaptic plasticity deficits after TBI.
Keywords: Cognition/Learning/Memory, Synaptic Function
NEUROPHYSIOLOGICAL AND GAIT DEFICITS DURING DUAL‐TASK CONDITIONS IN CONCUSSED ADOLESCENTS
1Department of Bioengineering, University Of Pennsylvania, Philadelphia PA, United States, 2Center for Injury Research and Prevention, The Children's Hospital of Philadelphia, Philadelphia PA, United States, 3School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia MI, USA, 4Department of Physical Therapy, The Children's Hospital of Philadelphia, Philadelphia MI, USA, 5Department of Psychology, College of Arts and Sciences, Drexel University, Philadelphia MI, USA, 6Drexel Solutions Institute, Drexel University, Philadelphia MI, USA, 7School of Nursing, University of Pennsylvania, Philadelphia MI, USA, 8Division of Rehabilitation Medicine, The Children's Hospital of Philadelphia, Philadelphia MI, USA, 9Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia MI, USA, 10Sports Medicine and Performance Center, Children's Hospital of Philadelphia, Philadelphia MI, USA
Gait deficits are common after concussion, can persist past symptom resolution, and are related to subsequent musculoskeletal injury. Dual‐task gait conditions combine locomotion with a cognitive task to provide a level of complexity useful for assessing gait deficits. Combining gait assessment with functional near‐infrared spectroscopy (fNIRS), a portable, non‐invasive neuroimaging technique, allows simultaneous assessment of neurophysiological and biomechanical deficits post‐injury. Uninjured (N = 16, 18.1 ± 0.6 years, 56% female) and concussed adolescents (N = 14, 17.3 ± 0.5 years, 86% female, 25.4 ± 9.5 days since injury) were assessed under three conditions (single‐task: walking, single‐task: serial subtraction, dual‐task: walking+serial subtraction) each repeated three times. Gait data was collected with seven inertial sensors and mean oxygenated hemoglobin concentration (HbO) of the anterior prefrontal cortex was collected via fNIRS. Neural efficiency (NE) was calculated by normalizing gait speed and mean HbO across participants and the single‐task walking and dual‐task conditions. Separate linear mixed‐effect models were used to evaluate the effects of task condition and injury status on gait outcomes, mean HbO, and NE. Concussed adolescents had significantly slower cadence (p = 0.01), shorter gait cycles (p = 0.01), and step duration (p = 0.01) during the dual‐task condition compared to uninjured adolescents. Concussed adolescents displayed significantly higher prefrontal cortical activation during single‐task subtraction (p = 0.002) and dual‐task (p = 0.002) conditions, and significantly lower NE during the dual‐task condition (p = 0.004) than uninjured adolescents. These findings emphasize that for concussed youth, complex tasks with a cognitive component manifest significant biomechanical and neurophysiological deficits. This work was supported by R01NR018425.
Keywords: Pediatric, Executive Function, Imaging, Concussion/mTBI
ERYTHROID TRANSIENT RECEPTOR POTENTIAL VANILLOID‐1, A KEY MODULATOR IN RED BLOOD CELLS‐MEDIATED BRAIN OXYGENATION AND CEREBRAL CIRCULATION AFTER TRAUMATIC BRAIN INJURY
1Department of Neurosurgery, Medical College of Georgia, Augusta University, Augusta GA, United States, 2Department of Pathology, Medical College of Georgia, Augusta University, Augusta GA, United States, 3Department of Oral Biology and Diagnostic Science, Dental College of Georgia, Augusta University, Augusta GA, United States, 4Department of Neurology, Medical College of Georgia, Augusta University, Augusta GA, United States
Cerebral hypoxia and loss of re‐oxygenation, secondary to global and regional changes in cerebral blood flow (CBF) and loss of erythroid rheology are clinically associated with increased morbidity and mortality after Traumatic brain injury (TBI). Given the role of calcium in RBC deformation, we hypothesized that modulation of Transient receptor potential vanilloid‐1 (TRPV1), a cation channel and pain receptor causes calcium influx in RBCs, and leads to loss of function by RBCs after TBI. We utilized moderate controlled‐cortical impact model of mice for TBI. Briefly, a craniotomy was made in the right parietal bone and brain was impacted at 3 m/s with 85 ms dwell time and 3 mm depression using a 3 mm diameter convex tip to mimic a moderate to severe TBI. Oxygenated RBCs were measured by Vevo Lazr‐X, while MRI was used to estimate edema and cerebral perfusion at 3 days post‐TBI. Mice were also tested for functional outcomes. Mice were sacrificed at 7th day post‐injury, blood was collected, fixed for electron microscopy and imaging. Statistical significance was determined at p < 0.05. TBI mice showed higher number of deformed RBCs resulted as a consequence of erroneous erythropoiesis and expressed high TRPV1 and Phosphoinositide Interacting Regulator of TRP Channels (PIRT), which mirrored loss of their elasticity, microthrombi formation, restricted CBF and lack of cerebral oxygenation. Our results demonstrate a key role for erythroid TRPV1‐PIRT in regulation of hypoxia and vaso‐occlusion, and may provide a therapeutic target and biomarker for loss of oxygenation and long‐term TBI outcomes.
Keywords: Biomarker, Secondary Injury, Hypoxia/Ischemia, Vascular, Cerebral Blood Flow
AUTOMATED PUPILLOMETRY FOR PREDICTION OF SPACE‐OCCUPYING HEMISPHERIC INFARCTION AFTER ENDOVASCULAR TREATMENT
1University of Erlangen‐Nuremberg, Department of Neurology, Erlangen, Germany
Keywords: Edema, Monitoring, Vascular, Neurocritical Care
FIBRIN(OGEN)‐INDUCED NUCLEAR FACTOR‐κB SIGNALING DURING MILD TRAUMATIC BRAIN INJURY IN MICE
1University Of South Florida, Tampa FL, United States
Activity of nuclear factor‐κB (NF‐kB) has been implicated in the pathogenesis of traumatic brain injury (TBI). Previously we showed that TBI increased blood level of fibrinogen that was associated with upregulation of inflammatory cytokines in astrocytes and in neurons, resulting in oxidative stress and neuronal death through activation of intercellular adhesion molecule‐1 (ICAM‐1). Since ICAM‐1 is regulated by NF‐kB, we tested if an interaction of fibrin(ogen) with its neuronal receptors, ICAM‐1 and cellular prion protein (PrPC), activates NF‐kB. Primary mouse brain cortex neurons from C57BL/6, wild‐type (WT) mice were pre‐treated with or without NF‐kB inhibitor, caffeic acid phenthyl ester (CAPE), prior to treatment with either media (control) or fibrinogen (1mg/mL). Separately, neurons were treated with or without fibrinogen in the presence of either a function‐blocking antibody against ICAM‐1 or a function‐blocking peptide against PrPC. Mild‐to‐moderate TBI was induced in WT and fibrinogen‐knockout (FgKO) mice. Fibrinogen‐induced increases in IκBα and interleukin‐6 mRNA levels detected in neurons were attenuated by inhibiting the functions of ICAM‐1 and PrPC or exposure to CAPE. An increase in DNA bound p65 in the nuclear extract of fibrinogen‐treated neurons was found via the TransAMTM NF‐kB‐p65 assay, a sensitive ELISA‐based method for the detection of specific transcription factor binding activity. A higher expression of NF‐kB‐p65 was found in brains from WT mice with TBI than that in brains from FgKO mice. We present novel evidence that NF‐kB is involved in fibrin(ogen)‐induced neuronal pathology suggesting that an interaction of fibrin(ogen) with ICAM‐1 and/or PrPC modulates NF‐kB activation in neurons.
Keywords: Neurodegeneration, Gene Expression, Concussion/mTBI, Inflammation/Immune Function, Receptor Mediated/Signaling, Neuropathology
EFFECT OF INJURY MECHANISM AND SEVERITY ON THE MOLECULAR PATHOPHYSIOLOGY OF TRAUMATIC BRAIN INJURY
1University Of Nebraska Lincoln, Lincoln NE, United States
Traumatic brain injury (TBI) mechanism and severity are heterogenous clinically; however, approximately 80% suffer from milder injuries. Thus, examining pathophysiological changes associated with mild TBI is imperative for improving clinical translation. Here, we employed derivations of the controlled cortical impact (CCI) model, including traditional CCI (tCCI, 4 m/s velocity, 2.5 mm depth), mild CCI with silicone tip (mTBI, 0.4 m/s velocity, 2.0 mm depth), and closed skull CCI with protective helmet (dTBI, 3.3 m/s velocity, 3.0, 9.0, and 15.0 mm depths). Injuries were performed on 8‐week old male C57BL/6J mice (N = 3), and perfused at 1, 3, and 7 days post‐injury. Ipsilateral and contralateral cortices (IC, CC) and hippocampi (IH, CH) were harvested for Western blot analyses to identify changes in necrosis (α‐II‐spectrin breakdown products, SBDPs) and autophagy biomarkers, LC3BII and SQSTM1. Following tCCI, we observed a peak in necrosis (145 kDa SBDP) in the IH at 3 days post‐injury (mean±SD, 13.365 ± 1.18, p < 0.001), coinciding with fold increases in LC3BII and SQSTM1 (8.3‐fold p < 0.05 and 2.13‐fold p < 0.05, respectively) indicating autophagosome accumulation and autophagic dysfunction. Following mTBI, we observed no significant changes in necrosis (145 kDa SBDP) or autophagy. Unexpectedly, while dTBI at 3.0 and 15.0 mm depths showed decreases in autophagy biomarkers, the 9.0 mm depth showed an increase in LC3BII (2.81‐fold p < 0.0001) with no significant changes in necrosis. Thus, these results suggest that cell death and survival mechanisms are highly variable depending on mechanism and severity of TBI. Overall, these results will aid in improving our understanding of mild TBI pathophysiology.
Keywords: Secondary Injury, Cell Death, Concussion/mTBI
INTRACRANIAL PRESSURE MAGNITUDE DURING BLAST EXPOSURE VARIES WITH LOCATION
1Virginia Tech, Blacksburg VA, United States, 2Salem Veterans Affairs Medical Center, Salem WA, United States
Blast‐induced traumatic brain injury (bTBI) occurs when a blast wave interacts with the head and energy is transmitted to the brain, leading to lasting neurological deficits. The mechanism of how energy is transmitted to the brain remains unclear. The objective of this work was to investigate the injury mechanism by characterizing the intracranial pressure (ICP) response across a range of overpressure magnitudes in a rat model. In this work, male Sprague Dawley rats (n = 5) were anesthetized, a pressure sensor was surgically implanted through the occiput, each subject was positioned head‐on in the Virginia Tech Advanced Blast Simulator (ABS), and then exposed to 12 blasts ranging from 5 to 25 psi. Biplane X‐ray and Hematoxylin & Eosin staining procedures were performed to confirm sensor location. It was found that ICP magnitude increased linearly with increasing static overpressure magnitudes, where R‐squared values ranged from 0.94 to 0.99. On a subject‐level, ICP magnitude increased by a factor of 1.30 to 1.86 times the static overpressure. Variability was found to be dependent on the sensor distance from the top of the skull (i.e. the closer to the top of the skull, the greater the increase in ICP magnitude relative to the static overpressure). Further, ICP traces showed an initial frequency response that was not visible in the static overpressure. These findings indicate that skull flexure, which is greater at the top of the skull, may be influencing a steep pressure gradient from superior to inferior regions where the cortex is disproportionately affected.
Keywords: Blast, Biomechanics, Intracranial Pressure
MORPHINE EXPOSURE FOLLOWING MILD TBI INCREASES ANXIETY‐LIKE BEHAVIOR AND ALTERS THE PROINFLAMMATORY RESPONSE TO INJURY IN MICE
1University Of Minnesota, Shoreview MN, United States
Rates of substance use disorder (SUD) among individuals with a history of traumatic brain injury (TBI) is 3‐6x greater than that of the general population. Experimental evidence has linked cocaine and alcohol SUD to the inflammatory response after TBI. Macrophages are prominent in the response to all severities of TBI, including the most common type, mild TBI. However, the mechanisms linking mild TBI and SUD is not understood, particularly to opioid addiction. Our laboratory charecterized a murine model of mild TBI where temporal changes in the inflammatory response correlated with behavioral deficits. Utilizing this model, mice with mild TBI or sham injury were given morphine (5mg/kg) or saline subcutaneously twice daily immediately after the procedure. The consequences of exposure to morphine following mild TBI was evaluated by changes in behavior, blood brain barrier (BBB) integrity, and immune cell infiltration. In an open field test, mice with mild TBI displayed increased anxiety‐like behavior two days post injury (dpi), which was not evident at 7dpi. However, mice with mild TBI and given morphine maintained higher levels of anxiety through 15dpi. Administration of morphine increased infiltrating macrophages in the brain at 3dpi greater than injury alone, and at 15 dpi increased CD8 T cells were found in the brain. These findings suggest that inflammatory mechanisms associated with TBI may influence SUD.
Keywords: Behavioral Function, Secondary Injury, Cognition/Learning/Memory, Blood Brain Barrier, Concussion/mTBI, Inflammation/Immune Function
ALTERED AQUAPORIN‐4 EXPRESSION AND DELAYED GLYMPHATIC IMPAIRMENT FOLLOWING BLAST INJURY
1University of Washington, Seattle WA, United States, 2VA Puget Sound Healthcare System, Seattle WA, United States, 3Uniformed Services University of the Health Sciences, Bethesda MD, United States
Mild traumatic brain injury (mTBI) has emerged as a potential risk factor for development of neurodegenerative conditions such as Alzheimer's disease (AD) and chronic traumatic encephalopathy (CTE). Blast mTBI, caused by exposure to a pressure wave from an explosion, is predominantly experienced by military personnel and has increased in prevalence and severity in recent decades. Yet the underlying pathology of blast mTBI and how it may differ from impact mTBI is largely unknown. One of the few studies that has examined the neuropathological changes in the blast‐exposed human brain reported a distinct pattern of astroglial scarring at the pial surface, white matter‐gray matter interface, and along penetrating cortical blood vessels. Given these astroglial changes, we hypothesized that blast exposure results in changes in localization of the astroglial water channel aquaporin‐4 (AQP4) and impairs AQP4‐dependent perivascular glymphatic exchange. We examined expression and localization of AQP4 in human post‐mortem frontal cortex and observed distinct laminar differences in AQP4 expression following blast exposure. In a mouse model of mild repetitive blast injury we examined altered AQP4 expression and localization. Measuring CSF tracer influx following repetitive blast mTBI, we observed delayed impairment of glymphatic function in blast exposed mice. Given the role of glymphatic exchange in the clearance of interstitial solutes such as Aβ and tau, these findings suggest that changes in AQP4 and delayed glymphatic impairment following blast injury may render the post‐traumatic brain vulnerable to neurodegeneration and suggest that pathophysiology and progression of blast injury may be fundamentally different from impact TBI.
Keywords: Astrocyte, Blast, Cerebrospinal Fluid, Neurodegeneration
CHRONIC DYSFUNCTION OF EXTRASYNAPTIC GABAA RECEPTORS IN MEDIODORSAL THALAMUS AFTER TRAUMATIC BRAIN INJURY
1University Of Washington, Seattle WA, United States
Traumatic brain injury (TBI) causes cellular and molecular changes that contribute to neuropsychiatric disease and epilepsy, including dysfunction of GABAergic signaling. The mediodorsal nucleus (MD) of the thalamus has broad connections that critically influence behaviors affected by TBI, including those involved in attention, cognitive function, and arousal. Compared to neocortex and hippocampus, much less is known about neurophysiological changes occurring in thalamocortical neurons after TBI. Tonic GABAergic inhibition mediated by delta‐subunit containing GABA(A) receptors has potent effects on firing properties and oscillatory network properties of thalamocortical neurons. Thus, we sought to investigate if TBI modifies extrasynaptic GABA(A) receptor function in the MD thalamus. Using murine ex vivo brain slices and patch‐clamp techniques, we measured tonic GABA currents in the presence of the delta subunit‐selective GABA(A) receptor agonist THIP (1‐10 M) after TBI (controlled cortical impact, CCI) or sham surgery. We found that THIP‐induced tonic currents showed significant reductions in MD neurons 8 months after TBI compared to controls (p = 0.0043 for TBI effect, mixed effects model). These results indicate that GABAergic dysfunction in MD neurons is a chronic consequence of TBI and motivates further investigation into thalamic dysfunction after TBI.
Keywords: Neurotransmitter, Synaptic Function
IDENTIFYING COMMON BRAIN NETWORKS ASSOCIATED WITH PAROXYSMAL SYMPATHETIC HYPERACTIVITY
1Oregon Health and Science University, Portland OR, United States, 2Brigham and Women's Hospital, Boston MA, United States, 3Massachusetts General Hospital, Boston MA, United States
Paroxysmal Sympathetic Hyperactivity (PSH) is a syndrome that occurs in patients with severe acquired brain injury. Disconnection of inhibitory pathways may play a role, but no common lesion location is known. We hypothesized that a common network may be disrupted in PSH.
We segmented lesions with reduced diffusivity on diffusion weighted imaging in traumatic brain injury patients with (n = 15) and without PSH (n = 32) then analyzed lesion overlap on a common brain template. Lesion maps and a public normative dataset based on 1000 control subjects were used to determine resting state functional connectivity between PSH lesion locations and networks in the brain.
Patients with PSH were younger than controls (27 ± 12 years v. 51 ± 21 years, p < 0.001). Patients with PSH also had a lower median GCS score of (3 [3‐4] v. 4 [3‐8], p = 0.04). There were no significant differences in race or sex between groups. Lesions located in the left posterior corpus callosum were associated with PSH. In an exploratory analysis, the location of this cluster was functionally connected to the mesial temporal lobe, fornix, lateral hypothalamus, parietal lobe, ventral midbrain, inferior cerebellum, and dorsal pons (T value >7, corrected p < 0.05).
Lesions in the left posterior corpus callosum and functional connections to the mesial temporal lobe, fornix, lateral hypothalamus, parietal lobe, ventral midbrain, inferior cerebellum, and dorsal pons may be associated with PSH.
Keywords: Imaging, Axonal Injury, Neurocritical Care, White Matter
SIMPLE WOUND CLOSURE COMPARED TO SURGERY FOR CIVILIAN CRANIAL GUNSHOT WOUNDS
1University of Miami, Miami FL, United States
The appropriate clinical scenario for utilizing simple wound closure (SWC) for civilian cranial gunshot wounds (CGSW) is not well described. We compared SWC and surgery patients in terms of their neurologic outcomes and incidence of infections, seizures, and additional operations. This was a single‐center, retrospective review of adult patients. Excluded were patients with non‐firearm penetrating injuries, initial Glasgow coma scale (GCS) 3, initial GCS 4 and nonreactive pupils, or mortality within 48 hours. Seventeen patients (25.4%) were treated with SWC and 50 (74.6%) were treated with surgery. The SWC group had a lower incidence of radiographic mass effect (3/17, 17.6% SWC versus 31/50, 62.0% surgery; p = .002) and lower incidence of involvement of the frontal sinus (0/0, 0.0% SWC versus 14/50, 28.0% surgery; p = .01). There were no differences in the frequency of Glasgow outcome scale extended scores ≥5 between the SWC and surgery groups at 30‐ (4/11, 36.4% SWC versus 12/35, 34.3% surgery), 60‐ (2/7, 28.6% SWC versus 8/26, 30.8% surgery), and 90‐days (3/8, 37.5% SWC versus 12/26, 46.2% surgery). There were no differences in the incidence of infections (1/17, 5.9% SWC versus 6/50, 12.0% surgery; p = .67), cerebrospinal fluid fistulas (2/11, 11.6% SWC versus 3/50, 6.0% surgery; p = .60), seizures (3/17, 17.6% SWC versus 9/50, 18.0% surgery; p = 1), and reoperations (3/17, 17.6% SWC versus 4/50, 8.0% surgery; p = .36) between the SWC and surgery groups. There were clinically relevant differences between the two groups. SWC is a safe and efficacious alternative therapy in a carefully selected subset of civilian CGSW patients.
Keywords: Ballistic Injury
REGIONAL CEREBRAL BLOOD FLOW ALTERATIONS AFTER ABUSIVE HEAD TRAUMA
Dr. Brenda Bartnik Olson1,
1Department of Radiology, Loma Linda University Medical Center, Loma Linda CA, United States, 2Department of Pediatrics, Loma Linda University Medical Center, Loma Linda CA, United States
Abusive head trauma (AHT) typically involves injury to the intracranial structures or skull of children younger than 5 and is the number one cause of death in children younger than 2 years old. Like traumatic brain injury (TBI), AHT pathology may involve secondary injuries including impaired cerebral blood flow (CBF). The purpose of this study is to assess the prevalence of CBF changes in pediatric patients being evaluated for AHT. Sixteen pediatric subjects being evaluated for AHT were retrospectively enrolled (mean age 6.38 ± 5.1 months, range 1 – 23 months). Subjects were dichotomized into 2 groups, head injury (HI)+ and HI‐, based on radiographic evidence of HI (skull fracture, epidural, or subdural hemorrhage). 3D T1 weighted and pseudo continuous arterial spin labeled (pCASL) MR images were acquired at 3T using a 64 channel receive‐only head coil. CBF images were co‐registered to structural MR images using ANTS (Advanced Normalization Tools Software), and regional cortical and subcortical CBF were measured using ITK‐SNAP. Results: In the HI+ group, 25% had skull fractures, 12.5% had epidural hemorrhage(s), and 75% had subdural hemorrhage(s). Additionally, 25% of the HI+ group showed evidence of hypoxic‐ischemic injury and were excluded from the CBF analysis. Compared to HI‐ subjects, CBF was reduced in the right precentral (p = 0.01) and right post‐central (p = 0.01) cortex of HI+. These findings suggest that hypoperfusion is a component of the pathological response to AHT and support further studies investigating the prognostic value of these abnormalities.
Keywords: Pediatric, Cerebral Blood Flow
DYSFUNCTIONAL GLUTAMATERGIC NEUROTRANSMISSION IN A PRECLINICAL MODEL OF CONCUSSION
1Graduate Program in Translational Biology, Medicine & Health, Virginia Tech, Blacksburg VA, United States, 2Department of Biomedical Engineering and Mechanics, College of Engineering, Virginia Tech, Blacksburg VA, United States, 3Salem Veterans Affairs Medical Center, Salem OR, United States
Concussions represent a major source of injury and disability in the United States with an estimated 1.6‐3.8 million concussions occurring annually. Changes in mood and development of mood disorders are commonly reported following concussion and dysfunctional glutamatergic neurotransmission may be a contributing factor. Downregulation of astrocytic glutamate transporters, GLAST and GLT‐1, has been observed in animal models of traumatic brain injury (TBI). Similar downregulation of these transporters is seen in mood disorders such as depression. Involvement of glutamatergic dysfunction in the development of mood disorders following concussion is not currently well understood. This study evaluated changes in glutamate transporter and reactive astrocyte expression in the prefrontal cortex (PFC), a brain region linked to post‐concussion neuropsychiatric sequelae. A closed‐head controlled cortical impact (CCI) was used to model mild TBI in 12‐week‐old male rats. The PFC of sham and CCI animals were analyzed seven days post‐injury for expression of GLAST, GLT‐1 and GFAP, a marker for astrogliosis. Overall, significant downregulation of GLAST (p = 0.0373) and trending downregulation in GFAP (p = 0.0651) were observed in the PFC of CCI animals with no expressional changes observed in GLT‐1 (p = 0.1432). Interestingly, hemispheric analyses revealed downregulation of GLAST in the ipsilateral (p = 0.0833) and contralateral (p = 0.0501) hemispheres of impact animals and trending decreases in GLT‐1 and GFAP, although not statistically significant. These findings suggest complex glutamatergic changes occur in the PFC at 7 days post‐concussion. Further evaluation of the link between concussion, temporal response and depression in corticolimbic structures is needed, including investigations of sex as a biological variable.
Keywords: Depression, Neurotoxicity, Concussion/mTBI, Synaptic Function
NEUROPEPTIDE RESPONSE IN TRAUMATIC BRAIN INJURY
1Faculdade De Medicina Da Universidade De Coimbra, Coimbra, Portugal
An animal model of TBI was used, with administration of intranasal NPY and assessment of pathological phenomena ‐ BBB disruption (quantification of albumin extravasation); cell death (cleaved caspase‐3 levels); microglia/astrocyte activation (morphological parameters); neuroinflammation (IL‐1β, iNOS).
Keywords: Neuroprotection, Secondary Injury, Blood Brain Barrier, Edema
ACUTELY MEASURED CIRCULATING LEVELS OF TAU PHOSPHORYLATED AT THREONINE‐181 (PTAU‐181) AS A DIAGNOSTIC BIOMARKER OF RADIOGRAPHIC INTRACRANIAL LESION AND PROGNOSTICATOR OF UNFAVORABLE NEUROLOGICAL OUTCOME FOLLOWING TRAUMATIC BRAIN INJURY (TBI)
1Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, United States
Keywords: Biomarker, Aging, Neurodegeneration, Axonal Injury, Neuropathology
CALORIC RESTRICTION DIFFERENTIALLY AFFECTS IMPULSIVITY, RISKY DECISION‐MAKING, AND MOTIVATION FOLLOWING TRAUMATIC BRAIN INJURY
1The Ohio State University, Columbus OH, United States, 2West Virginia University, Morgantown WV, United States
Traumatic brain injuries (TBIs) increase risk for psychiatric disorders and subclinical symptoms, including deficits in impulsivity and risky decision‐making. The gut microbiome is a particularly interesting candidate for the evolution of these deficits. Prior research in our laboratory has extensively used food‐restricted rats to motivate responding, which may also influence the gut microbiome. In the current study, rats were trained on the Rodent Gambling Task (RGT), which measured decision‐making via four choices, two high risk versus two optimal low risk. To measure impulsivity, the rats were to inhibit responding until given a light prompt. Motivation was measured by response latencies and omissions. Rats were assigned to free‐feeding or food‐restricted. After behavioral baseline was determined, rats received a moderate‐to‐severe bilateral frontal controlled cortical impact injury. Pre‐injury, free‐feeding increased omitted trials, reduced impulsivity, and led to fewer reinforcers. However, decision‐making was unchanged. Post‐injury, free‐feeding did not significantly impact decision making, but decreased trials, pellet collection, and premature responding. Ongoing studies are determining the effects of TBI and caloric restriction on the gut microbiome and markers of brain inflammation. In conclusion, caloric restriction is useful to measure impulsivity and motivation, but may not drastically affect decision‐making. More work is needed to determine if the effects on the gut microbiome are drastic enough to warrant the loss of resolution in measuring impulsive behavior which accompanies free‐feeding.
Keywords: Behavioral Function, Executive Function
EFFECTS OF DOCOSAHEXAENOIC ACID AND SEX ON EX VIVO PHAGOCYTIC CAPACITY AND OXIDATIVE POTENTIAL OF MICROGLIA AND MACROPHAGES IN RAT PUP BRAIN AFTER CONTROLLED CORTICAL IMPACT
1University Of Utah, Salt Lake City UT, United States, 2University of Maryland, Baltimore MD, United States, 3Trinity College University of Dublin, Dublin, Ireland
Inflammation and oxidative stress adversely affect pediatric traumatic brain injury (pTBI). In our rat pup pTBI model using controlled cortical impact (CCI) Docosahexaenoic Acid (DHA) decreased microglial inflammatory markers, oxidative stress and adverse outcomes. Whether DHA affects microglial phagocytic capacity and oxidative potential after TBI in either sex is unknown. We hypothesized that CCI increases ex vivo phagocytosis and oxidative potential of microglia (mμ) and macrophages (MO) at Post Injury Day (PID) 1, 3 and 7, blunted by DHA and female sex. 17 day old male/ female rats received CCI/SHAM followed by vehicle/ DHA. We sorted rat brain cells into CD11b +/CD45 hi/lo (MO/mμ) and CD11b(‐)(NEGS, mainly neurons and astrocytes) after exposure to fluorescent beads or DHR123 to assess phagocytic capacity and oxidative potential and assayed using ImageStream® and flow cytometry. At PID1, CCI increased microglial phagocytic capacity relative to control (47 ± 1.4 vs 29 ± 1.4 % positive cells, p < 0.0001). Interestingly, microglia showed greater beads/cell than other CD11b+ cells. CCI increased oxidative potential in MO (25 ± 4.2 vs 2.9 ± 0.6% positive cells p = 0.003) and in an “intermediate” population we unexpectedly found at PID1 (not at 3 nor 7: CD11b+/CD45int) relative to controls (25 ± 3.4 vs 3.4 ± 0.6, p = 0.003). By histology and cytospin, these cells are not neutrophils but MO and monocytes. We report novel, ex vivo, functional assays of inflammation in the developing brain after TBI. We anticipate that DHA and female sex will blunt injury at PID 7 and PID1. We speculate that intermediates are blood monocytes that enter the brain transiently after CCI.
Keywords: Pediatric, Neuroprotection, Microglia, Inflammation/Immune Function
LINKS BETWEEN GUT MICROBIOME AND BLOOD AND BRAIN METABOLITE AVAILABILITY AFTER BRAIN INJURY
1Ohio State University, Columbus OH, United States, 2West Virginia University, Morgantown WV, United States
The gut microbiome is disrupted as a result of brain injury. This is most evident in the acute post‐injury period, although disruptions may continue chronically. It is not yet clear whether this disruption has any effects on the progression of symptoms related to brain injury. Because psychiatric symptoms develop slowly over time after injury, the current project sought to evaluate the degree to which monoaminergic pathways were affected by TBI and gut‐mediated processing of food. Rats were given a bilateral frontal controlled cortical impact and euthanized at 24 h, 72 h, or 7 days after injury. Twenty‐six hours prior to euthanasia, rats were food deprived. Two hours prior to euthanasia, blood samples were taken along with fecal samples. Rats were then given an oral gavage of liquid diet. Blood was taken again 2 hours later and brains extracted. Blood and brain were analyzed using HPLC/MS for targeted analysis of metabolites along the dopamine and serotonin synthesis pathways. Gut bacteria were analyzed with 16S sequencing to determine predicted metagenomic functional disruptions in these same pathways. TBI disrupted metabolite availability in the blood and altered the gut microbiome. Brain metabolomics analyses are ongoing. Though this study represents an important first step, additional research is needed to strengthen causal relations between the gut microbiome and brain function. Future studies will seek to determine whether bioavailability of metabolic products is solely regulated by changes in the gut microbiome and whether treatment focused on this may restore function.
Keywords: Biomarker, Biomaterials, Nutrition, Metabolism/Energetics
INCREASED RESTING‐STATE BETA AND GAMMA ACTIVITY IN FRONTAL AND CENTRAL BRAIN AREAS IN ADOLESCENTS WITH MILD TRAUMATIC BRAIN INJURY
Christopher Edgar, Lisa Blaskey, Olivia Podolak, Drayton Murray, Marybeth Macnamee, Kimberly Konka, Jeffrey Berman, Timothy Roberts, Dr. Kristy Arbogast,
Children's Hospital Of Philadelphia/University Of Pennsylvania Perelman School Of Medicine
Mild traumatic brain injury (mTBI) is common in adolescents, often resulting in significant cognitive and physiological impairment. However, the clinical assessment of mTBI is subjective and imprecise, and our understanding of brain pathology associated with mTBI is meager, as structural deficits are not identifiable via standard imaging (e.g., CT/MRI). In the present study, magnetoencephalography (MEG) data were obtained during a resting‐state (RS) eyes‐closed exam, with source localization examining activity in brain space. Evaluable RS data were obtained from 47 adolescents with mTBI (average age = 15.3 years, SD = 1.7, 25 females) within 3 months of their concussion (range 4‐90 days) and 49 controls (average age = 15.2 years, SD = 1.6, 13 females). Group differences were examined in standard frequency bands via t‐tests, with a cluster threshold of p < 0.05 for 5+ frequency bins and family‐wise correction applied. Adolescents with mTBI showed reduced theta (4‐8Hz), beta (16‐30Hz), and gamma power (30‐55Hz), most prominent at frontal and central brain areas. Exploratory analyses examining group differences as a function of sex, given an extensive literature showing that adolescent brain rhythms often differ between males and females, suggested that group differences were more pronounced in females than males. The frontal focus potentially reflects the fact that frontal and temporal pole areas are more likely than other brain areas to be damaged following brain injury, and the present findings indicate the need to consider sex differences in mTBI pathophysiology. Ongoing analyses will relate these observed patterns in RS activity to clinical symptoms, in order to understand the clinical implications of the findings.
Keywords: Pediatric, Concussion/mTBI
FUNCTIONAL NEAR INFRARED SPECTROSCOPY DISTINGUISHES VISUAL COGNITIVE WORKLOAD BEFORE AND AFTER CONCUSSION
1Children's Hospital Of Philadelphia, Philadelphia PA, United States, 2University Of Pennsylvania Perelman School Of Medicine, Philadelphia PA, United States, 3Drexel University, Philadelphia PA, United States, 4University of Pennsylvania School of Nursing, Philadelphia PA, United States, 5Georgia Institute of Technology, Atlanta GA, United States
Keywords: Concussion/mTBI
IMPAIRMENT OF MITOCHONDRIA TARGETED POST‐INJURY MECHANISMS IN THE RAT MODEL OF PENETRATING TBI
1Walter Reed Army Institute Of Research (WRAIR), Silver Spring MD, United States
Mitochondrial dysfunction is a commonality among various severity of traumatic brain injury (TBI) that leads to secondary injury progression. Abnormal mitochondrial function following TBI includes impaired energy, Ca2+ and redox homeostasis. Oxidative stress further causes irreversible oxidative modifications of biomembrane components, alters membrane integrity and triggers apoptosis. The current study evaluates the mitochondria targeted post‐injury mechanisms following penetrating TBI (PTBI). Anesthetized adult male rats were subjected to either 10% unilateral PTBI or uninjured Sham craniectomy (n = 6/group). Animals were euthanized at 24h post‐PTBI, and mitochondria isolated from the injury core and perilesional frontal cortex and striatum regions. At 24hr post‐injury, a significantly higher free radicals production, elevated lipid and protein oxidative markers were observed following PTBI vs. Sham. Together, mitochondrial antioxidants such as glutathione, peroxiredoxins‐3, thioredoxins, NADPH, superoxide dismutase expression/levels were significantly decreased following PTBI. The PTBI mitochondria displayed significant loss of Ca2+ homeostasis, early opening of mitochondrial permeability transition pore and increased Ca2+ induced mitochondrial swelling. Mitochondrial membrane integrity markers such as VDAC and cytochrome c expression were significantly decreased following PTBI. This may further exacerbate apoptotic cell death as evidenced by decreased anti‐apoptotic protein BCL‐2, and increased apoptotic GAPDH protein expression following PTBI. Overall, the PTBI group showed increased oxidative stress, decreased antioxidants, decreased Ca2+ load capacity at 24h post‐injury. The significant loss of mitochondrial membrane integrity and elevated apoptosis indicators may contribute to non‐salvageable acute‐phase effects following PTBI. Collectively, the current results suggest that, mitochondria targeted neuroprotective intervention is crucial for preserving brain functions during acute‐phase of PTBI.
Keywords: Excitotoxicity, Neuroprotection, Metabolism/Energetics, Free Radicals
PENETRATING BRAIN INJURIES – EVALUATION OF PATIENT OUTCOMES AND A CARE ALGORITHM FROM A LEVEL 1 TRAUMA CENTER
1University Of Florida College Of Medicine, Jacksonville FL, United States
Penetrating Brain injuries are less prevalent than closed head injury but carry a worse prognosis. Management of these complex injuries continues to present controversies and challenges as outcomes are variable and there are no specific recommendations to guide practice.
Keywords: Ballistic Injury
THE INFLUENCE OF AEROBIC EXERCISE ON LEARNING AND MEMORY AFTER MTBI IN MICE
Ms. Liron Tseitlin1, Dr. Lior Bikovski2,3, Dr. Shaul Schreiber4,5,6,
1Department of Anatomy, Tel Aviv University Sackler Faculty of Medicine, Tel Aviv, Israel, 2Myers Neuro‐Behavioral Core Facility, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel, 3School of Behavioral Sciences, Netanya Academic College, Netanya, Israel, 4Department of Psychiatry, Tel Aviv Sourasky Medical Center, Tel Aviv , Israel, 5Dr. Miriam and Sheldon G. Adelson Clinic for Drug Abuse Treatment and Research, Tel Aviv Sourasky Medical Center , Tel Aviv, Israel, 6Sagol School of Neuroscience, Sackler Faculty of Medicine,Tel Aviv University , Tel Aviv, Israel, 7Dr. Miriam and Sheldon G. Adelson Chair and Center for the Biology of Addictive Diseases, Tel‐Aviv University, Tel Aviv , Israel, 8Sylvan Adams Sports Institute, Tel Aviv University , Tel Aviv , Israel
Keywords: Neuroprotection, Behavioral Function, Cognition/Learning/Memory, Regeneration & Plasticity
α7 NICOTINIC ACETYLCHOLINERGIC RECEPTOR MODULATION AND ENVIRONMENTAL ENRICHMENT HAVE POSITIVE EFFECTS ON SUSTAINED ATTENTION, CHOLINERGIC NEUROTRANSMISSION, AND SYSTEMIC INFLAMMATION FOLLOWING CONTROLLED CORTICAL IMPACT IN RATS
1UPMC Dept. of PM&R, Pittsburgh PA, United States, 2Safar Center for Resuscitation Research, Pittsburgh PA, United States, 3University of Pittsburgh, Pittsburgh PA, United States
Post‐traumatic brain injury (TBI) attentional domain impairments lack proven treatments and can result from cholinergic dysfunction. We hypothesized NS‐1738, a novel α7 nicotinic acetylcholine (Ach) receptor (α7‐NAChR) type‐I positive allosteric modulator (PAM), could improve sustained attention post‐TBI. Adult male rats trained in the 3‐choice serial reaction time task (3‐CSRT) reached stable pre‐injury baselines prior to moderate severity right parietal controlled cortical impact (CCI) or sham injury. Rats were randomized to receive NS‐1738 (3 mg/kg) or vehicle (1 mL/kg saline) beginning post‐injury day (PID) 1, then continued once daily [subacute (7d); chronic (28d)]. The chronic paradigm co‐investigated daily environmental enrichment (EE; 6h/d). 3‐CSRT retrials occurred on PID 14‐24 with sacrifice PID 30. Western blots of medial prefrontal cortex (mPFC) assessed cholinergic markers [acetylcholinesterase (AChE), choline acetyltransferase (ChAT), and α7‐NAChR]. Microarrays examined serum inflammatory gene expression. Statistical analysis was performed with ANOVAs with Newman‐Keuls post hoc tests.
TBI rats demonstrated impaired 3‐CSRT sustained attention compared to shams (p < 0.05), which was not ameliorated by subacute NS‐1738 (p > 0.05). However, ongoing work suggests chronic NS‐1738 improves post‐TBI sustained attention, with drug+EE rendering an additive effect: reducing omissions. Drug+EE treatment also improved inflammatory markers (p < 0.05) including TREM‐1 (triggering receptor expressed on myeloid cells‐1) and IL‐1 RA (interleukin‐1 receptor antagonist). TBI notably decreased mPFC cholinergic markers ChAT and AchE (p < 0.05) with partial restoration by NS‐1738. These preliminary findings support possible benefits of α7‐NAChR type‐I PAM and/or EE treatment after experimental TBI in sustained attention, cholinergic neurotransmission, and systemic inflammation.
Keywords: Rehabilitation, Behavioral Function, Neurotransmitter, Cognition/Learning/Memory, Executive Function, Inflammation/Immune Function, Receptor Mediated/Signaling, Attention
DEVELOPMENT OF A TOUCHSCREEN FOR ASSESSING PIG BEHAVIORAL FUNCTION
1Ohio State University, Columbus OH, USA, 2Utah State University, Salt Lake City UT, USA
Pigs are becoming increasingly common models for neurotrauma research. There are key benefits to the size of the brain, ratio of grey and white matter, and large gyri which more closely mimic the human brain relative to rodent models. However, behavioral analysis of pigs is relatively limited, partially due to training time required and space constraints for pig‐sized apparatuses. Thus, the current project evaluated the use of a touchscreen device to behaviorally train pigs. Two iterations were constructed. The first was not strong enough to withstand daily pig interaction. The second used an industrial‐strength touchscreen, was fully enclosed in a metal frame and withstood repeated testing over several weeks. Pigs were trained to walk to the testing room and respond to the screen for fruit‐flavored sucrose pellets. Two male pigs were tested on a delay discounting task to measure impulsivity. Two female pigs were tested on a simple color discrimination task. Pigs acquired response to the touchscreen within several sessions and were able to perform both tasks. The male pigs exhibited strong aversion to reinforcement delays, indicative of impulsive behavior. The female pigs rapidly acquired a simple discrimination, but were relatively inaccurate matching to a sample (e.g., show green, must pick green). Because these experiments were primarily designed to assess the stability/capability of the device, more work is needed to refine behavioral training protocols and optimize behaviors which can be either 1) rapidly assessed after injury or 2) are suitable for repeated long‐term testing.
Keywords: Behavioral Function, Cognition/Learning/Memory, Executive Function, Attention
CHARACTERIZATION OF A FERRET MODEL OF UNDER‐VEHICLE BLAST‐INDUCED TRAUMATIC BRAIN INJURY
1University Of Maryland School Of Medicine, Baltimore MD, United States, 2University of Maryland‐ College Park, College Park MD, United States
Under‐vehicle blast (UVB) causes a unique TBI in warfighters targeted by improvised explosive devices. UVB hyperacceleration produces an impact‐independent TBI, however, an impact injury can also occur. While rodent UVB studies are useful, translating findings into improved patient outcomes is challenging, perhaps because rodents lack human‐like brain gyrification. Thus, a UVB model was developed in gyrencephalic ferrets.
Adult male ferrets were exposed to UVB via pentaerythritol tetranitrate detonation (2000–2500G), controlled cortical impact (CCI; 4 – 6mm depth), combined UVB+CCI (BCCI), or sham injury (craniotomy). Six days post‐injury (dpi), mood (play behavior), motor dysfunction (ladder walk, open field), and memory (novel object recognition and location) were assessed. A subset of UVB‐alone and BCCI ferrets received magnetic resonance spectroscopy (MRS) scans at baseline and 7dpi. Ferrets were euthanized 7dpi for brain histologic analysis.
Relative to shams, BCCI animals demonstrated impaired spatial memory, hyperactivity, and putative elevations in anxiety‐like behavior. MRS showed altered neurochemical concentrations following BCCI, suggesting impaired neurotransmission and energy generation, neuronal injury/death, and oxidative stress. Finally, compared to shams, UVB‐ and CCI‐alone generated elevated immunoglobulin (IgG) staining, indicative of BBB disruption. CCI‐alone caused robust diffuse axonal injury compared to sham and UVB‐alone, demonstrated by beta‐amyloid precursor protein (βAPP) staining. BCCI did not exacerbate IgG or βAPP. Results were significant p < 0.05.
Neuropathological outcomes in this model closely mirror those of human blast survivors. The model will next be applied to evaluate secondary injury following aeromedical evacuation (hypobaria) to inform protocols for safe transport of injured personnel.
Keywords: Behavioral Function, Blast, Blood Brain Barrier, Imaging
FLIGHT‐RELEVANT HYPOBARIA WORSENS NEUROPATHOLOGIC AND BEHAVIORAL OUTCOMES IN RATS FOLLOWING THE COMBINATION OF UNDER VEHICLE BLAST AND CONTROLLED CORTICAL IMPACT
1University Of Maryland School Of Medicine Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR) , Baltimore MD, United States, 2University of Maryland‐ College Park, College Park MD, United States
US warfighters experience a high incidence of blast ± impact TBI, often resulting in persistent neurologic impairment. We developed a small‐scale model of “under‐vehicle” blast followed by controlled cortical impact (BCCI) to test the hypothesis that aeromedical evacuation‐relevant hypobaria exposure ( = 8000 ft) one day post‐injury (dpi) results in increased behavioral deficits, cortical inflammation, and cerebellar cell death compared to ground transport (normobaria).
Under‐vehicle blast was induced via pentaerythritol tetranitrate detonation (1800G), followed immediately by CCI. At 1dpi, rats were placed inside an altitude chamber under normobaric or hypobaric pressures in either normoxic (21‐28% O2) or hyperoxic (50% O2) conditions for 6 hours. The elevated plus maze assessed anxiety‐like behavior at 2, 7, and 14dpi. Cortical inflammation (ED1 and myeloperoxidase (MPO)) and cerebellar injury (calbindin) were quantified using immunohistochemistry on 2 or 14dpi.
BCCI animals showed an acute and transient increase in cortical MPO+ neutrophils (2x) and peri‐lesional astrocytes (7x) on 2dpi. On 14dpi, BCCI animals exhibited elevated numbers of injured and dark cerebellar Purkinje cells. These histologic changes were not exacerbated by hypobaria though moderate hyperoxia during hypobaria improved cerebellar cell survival. Both anxiety‐like behavior and cortical penumbral inflammation were elevated in BCCI following hypobaria 14dpi.
BCCI induces an acute increase in cortical glial activation and persistent cerebellar injury. Subsequent hypobaria exposure increases long‐term cortical inflammation and anxiety‐like behavior in rats. These results raise concerns that trauma patient exposure to hypobaria during aeromedical transport can worsen neurologic outcomes.
Keywords: Behavioral Function, Blast, Cell Death, Inflammation/Immune Function
EVALUATING CATHEPSIN B AND ITS ROLE IN NEURONAL MEMBRANE DISRUPTION FOLLOWING DIFFUSE BRAIN INJURY IN RATS
1Virginia Commonwealth University, Richmond VA, United States
Traumatic brain injury (TBI) has consequences that last for years following injury and are associated with diffuse pathology. While TBI can precipitate a variety of diffuse pathologies, the mechanisms involved in injury‐induced neuronal membrane disruption remain elusive. Additionally, elevations in intracranial pressure (ICP) has been associated with increased neuronal membrane disruption. The lysosomal cysteine protease, Cathepsin B (Cath B), and specifically its redistribution into the cytosol upon membrane disruption has been implicated in cell death. While Cath B expression and activity in the lateral neocortex does not change with TBI compared to sham, immunohistological studies, revealed a sub‐cellular re‐localization of Cath B at 2w and 4w post‐injury in the membrane disrupted neuronal population. Therefore, the current study evaluated Cath B and diffuse neuronal membrane disruption over a more chronic post‐injury window paired with 20mmHg ICP elevation. We evaluated Cath B in adult male Sprague‐Dawley rats at 2w following central fluid percussion injury (CFPI). In order to focus on Cath B and its role in membrane disruption, we administered CA‐074Me (10 μg/μL), a Cath B inhibitor, into the left lateral ventricle and assessed both left and right cortices, alongside the liver to evaluate systemic Cath B inhibition. Expression of Cath B was assessed using western blot analysis. Cath B activity was assessed with the fluorescent substrate, z‐F‐R‐AMC, in sham and CFPI animals, and CFPI + ICP elevation animals. Furthering our understanding of Cath B and its role in neuronal membrane disruption has implications for future treatment for TBI.
Keywords: Concussion/mTBI, Intracranial Pressure, Receptor Mediated/Signaling, Neuropathology
COMBINATION OF FACTORS REPROGRAM ASTROCYTES INTO NEURONS IN ADULT SPINAL CORD
1University of Texas Southwestern Medical Center, Molecular Biology, Dallas TX, United States, 2University of Texas Southwestern Medical Center, Hamon Center for Regenerative Science and Medicine, Dallas TX, United States
Spinal cord injury (SCI) can cause severe disability and mortality. SCI induces reactive gliosis but not neurogenesis. In the present study, we conducted in vivo screens of transcription factors for their ability of induced neurogenesis. Our screens found that a combination of factors mainly including NGN2 and microRNAs, could induce neurons from resident astrocytes of the adult spinal cord. Lineage tracing in transgenic mice confirmed that the induced neurons mainly originated from astrocytes with minor contributions from NG2 glia. Further examining the role of each of the factors in the combination in the process of reprogramming, we found that NGN2 is essential, whereas microRNAs can improve the reprogramming efficiency and promote maturation of the reprogrammed neurons. The time‐course analysis showed that the combination of factors could induce neurons as early as 1 week post virus injection; the number of induced neurons increased with time and reached to a peak level at 4 weeks after virus injection. These results show that the combination of factors can reprogram astrocytes into mature neurons within 4 weeks, which might provide a potential therapeutic strategy for SCI.
Keywords: Astrocyte, Regeneration & Plasticity, Neurogenesis
INTER‐HOSPITAL VARIABILITY IN NEUROSURGERY IS LARGEST FOR ISOLATED SUBDURAL HEMORRHAGES: A NATIONWIDE 13‐YEAR REVIEW OF MILD TRAUMATIC BRAIN INJURIES WITH INTRACRANIAL HEMORRHAGE
1Johns Hopkins Bloomberg School Of Public Health, Baltimore MD, USA, 2Medical City Plano, Plano TX, USA, 3Swedish Medical Center, Englewood CO, USA, 4Wesley Medical Center, Wichita KS, USA, 5Penrose Hospital, Colorado Springs CO, USA, 6St. Anthony Hospital, Lakewood CA, USA
Keywords: Concussion/mTBI, Hemorrhage, Neurocritical Care
SIGNIFICANT NATIONAL DECLINES IN NEUROSURGERY IN THE SETTING OF MILD TRAUMATIC BRAIN INJURY WITH INTRACRANIAL HEMORRHAGE: A 13‐YEAR REVIEW OF THE NATIONAL TRAUMA DATA BANK
1Johns Hopkins Bloomberg School of Public Health, Baltimore MD, USA, 2Medical City Plano, Plano TX, USA, 3Swedish Medical Center, Englewood CO, USA, 4Wesley Medical Center, Wichita KS, USA, 5Penrose Hospital, Colorado Springs CO, USA, 6St. Anthony Hospital, Lakewood CA, USA
Keywords: Concussion/mTBI, Hemorrhage, Neurocritical Care
HIGH INTENSITY BLAST EXPOSURE LEADS TO TEMPORAL ALTERATIONS IN CEREBROVASCULAR GLYCOCALYX
1Henry M. Jackson Foundation for the Advancement of Military Medicine, Silver Spring MD, United States, 2Naval Medical Research Center, Silver Spring MD, United States, 3Parsons Corporation, Columbia SC, United States, 4Uniformed Services University of the Health Sciences, Bethesda MD, United States
Blast‐related traumatic brain injury (bTBI) is a prevalent concern among military personnel. bTBI has been shown to alter cerebral vasculature leading to vascular pathologies. Endothelial glycocalyx is essential in maintaining the structural and functional integrity of the vasculature and is prone to damage due to the initial mechanical insult and the pathological processes that are initiated by blast exposure. This study assessed temporal alterations in the density of glycocalyx and its proteoglycan‐glycoprotein‐glycosaminoglycan components (heparan sulphate proteoglycan (HSPG/syndecan‐2), heparan sulphate (HS), and chondroitin sulphate (CS)) at 2‐3 hours, 1, 3, 14, and 28 days after 132 kPa blast exposure in rats. Microstructural assessment of glycocalyx in frontal cortex was done using electron microscopy (EM) and the concentration of proteoglycan‐glycoprotein‐glycosaminoglycan components in frontal cortex and plasma was determined by enzyme‐linked immunosorbent assay. EM showed a significant shedding and reduction in the thickness of glycocalyx at 2‐3 h, 1 and 3 days post‐blast and recovery by 28 days. A significant increase in HS (14 and 28 days), HSPG/syndecan‐2 and CS (28 days) was observed in frontal cortex whereas no significant changes were seen in plasma. The data shows degradation of glycocalyx in the early phase (up to 3 days) and recovery in the delayed phase (14 and 28 days) after blast exposure. Given the role of glycocalyx in physiological function of the cerebral vasculature, damage to glycocalyx early on after bTBI may result in the onset of pathogenesis and progression of cerebrovascular dysfunction leading to neuropathology.
Keywords: Biomarker, Ballistic Injury, Vascular, Cerebral Blood Flow
SENESCENT‐LIKE NEURONS ACCUMULATE AFTER TRAUMATIC BRAIN INJURY POSSIBLY LIMIT THE THERAPEUTIC POTENTIAL OF SENOLYTIC DRUG ABT263
1Laboratory Medicine and Pathobiology, University of Toronto, Canada, Toronto, Canada, 2Department of Pediatric Lab Medicine, The Hospital for Sick Children, Toronto, Canada, Toronto, Canada, 3Neuroscience and Mental Health, The Peter Gilgan Centre for Research and Learning, Toronto, Canada, Toronto, Canada
Mild traumatic brain injury (mTBI) leads to long‐term neurological impairment and a propensity towards neurodegenerative diseases, although the molecular mechanisms driving this are unclear. The objective of this study is to characterize and target cellular senescence in a mouse model of mTBI. Methods: In the current study, sex‐balanced groups of C57BL/6 mice received three mTBIs, each 24h apart, or sham procedures, followed by behavioural testing or tissue analysis one week later. Results: We found that closed skull mild injury elicited prolonged righting reflex, neurocognitive impairment in the Morris water maze test, and evidence of gliosis and microgliosis despite the absence of any gross lesion in both males and females. In the cortical and hippocampal region near injury site, we found evidence of DNA damage (double strand breaks, oxidative damage, and R‐loops), senescence (elevated p16 and p21), and neuroinflammation in a sex‐specific manner. Single‐cell RNA sequencing revealed neurons with senescent‐like features, including the DNA damage response and the senescence‐associated secretory phenotype (SASP), and cell‐type specific changes consistent with innate immune activation, synaptic dysfunction indicating excitotoxicity, gliosis, and metabolic reprogramming. Treatment with the senolytic agent ABT‐263, which selectively eliminates senescent cells, improved behavioural performance and reduced markers of DNA damage and senescence, but did not significantly reduce inflammation. Conclusion: This study shows compelling evidence that senescence is a viable clinical target, but we conclude that more targeted strategies towards inflammation that do not eliminate cell populations and that may be sex‐specific will be critical in the future treatment of mTBI
Keywords: Secondary Injury, Aging, Gene Expression, Concussion/mTBI
STROKE OUTCOMES AFTER MILD TRAUMATIC BRAIN INJURY ARE TIME AND SEX DEPENDENT IN MICE
1West Virginia University, Morgantown WV, United States
Traumatic Brain Injuries (TBI) have lasting physical and cognitive consequences, and can lead to cerebrovascular dysfunction. There is significant epidemiological evidence that TBI is associated with increased incidence of ischemic stroke. Experimental TBI exacerbates stroke outcomes in mice. Due to the link among TBI, ischemic stroke, and cerebrovascular function, we have hypothesized that TBI‐induced impairments have long lasting roles in stroke outcomes. To test this hypothesis, we performed mild closed‐head TBI or a control procedure on 6‐8 week old Swiss‐Webster mice. We then performed a transient middle cerebral artery occlusion (MCAO) for one hour either 7‐ or‐28 days post‐injury, and used laser speckle flowmetry to measure cerebral blood flow. In additional cohorts of mice, we conducted behavioral testing to measure motor impairments five days after occluder removal and measured infarct volume using 2,3,5‐Triphenyltetrazolium choloride (TTC) staining. We also induced mild TBI and collected brains at either 7‐or 28‐days post‐injury for immunohistochemistry (IHC) to assess changes in astrocyte morphology. Finally, we performed a blood‐brain barrier permeability assay and IHC analysis on collected brains for CD31 expression to measure endothelial cell accumulation of extravasated tracer. Sex differences emerged with female mice showing more persistent vulnerability, while male mice had reduced vulnerability by 28 days after the injury. These data suggest sex differences in cerebrovascular responses after TBI that can cause differential severities of stroke responses over time post‐TBI.
Keywords: Secondary Injury, Astrocyte, Blood Brain Barrier, Concussion/mTBI, Vascular, Cerebral Blood Flow
MICROBIOME DISRUPTION WITH ANTIBIOTICS PRIOR TO BRAIN INJURY DELAYS IMPAIRMENT ON THE RODENT GAMBLING TASK
1The Ohio State University, Columbus OH, United States, 2West Virginia University, Morgantown WV, United States
Traumatic brain injury (TBI) results in chronic psychiatric symptoms including risky decision‐making and impulsivity. It is unclear how these symptoms develop after TBI. Brain injury can lead to gut dysbiosis that can disrupt the brain‐gut communication network. An antibiotic cocktail can induce gut dysbiosis and increase depressive‐ and anxiety‐like symptoms. This study sought to assess the role of the gut microbiome in the development of psychiatric deficits after TBI by inducing gut dysbiosis with an antibiotic cocktail prior to injury. An operant behavioral task, the rodent gambling task (RGT), was used to measure risky decision‐making and impulsivity. The RGT has four different choice options with varying corresponding probabilities of reinforcement or punishment, with two safe choices (lower magnitude of reinforcement, but more optimal) and two risky options (higher magnitude of reinforcement, but overall detrimental). After a stable behavioral baseline was established, an antibiotic cocktail consisting of Bacitracin, Neomycin sulfate, Vancomycin, and Pimaricin or vehicle was administered in water for three weeks. Drug treatment was stopped 72 h before receiving a bilateral frontal controlled cortical impact or sham injury. Antibiotics alone did not impact optimal decision‐making or impulsivity prior to injury. TBI increased impulsivity and decreased optimal decision‐making, but antibiotics delayed the onset of decision‐making deficits injury in the TBI group. Ongoing work will determine the specific changes to the gut microbiome which accompanied this behavioral phenotype.
Keywords: Behavioral Function, Executive Function
HEAD IMPACTS AND BRAIN‐DERIVED BLOOD BIOMARKERS DIFFER BETWEEN MALE AND FEMALE COLLEGIATE ICE HOCKEY PLAYERS
1Lewis Katz School of Medicine, Temple University, Philadelphia MI, USA, 2Department of Exercise and Sport Performance, University of New England, Biddeford ME, USA
Keywords: Biomarker, Concussion/mTBI
REPEATED LOW‐LEVEL BLAST INDUCES CHRONIC NEUROBEHAVIORAL CHANGES
1New Jersey Institute Of Technology, Newark NJ, United States, 2Center for Injury Biomechanics, Materials and Medicine, Newark NJ, United States
Service members and law enforcement experience repeated blast exposures frequently due to the constant use of heavy weaponry including large caliber rifles and explosives. While injury is always associated with overt symptoms, exposure to repeated low‐level blasts can led to cognitive impairments, attention deficits and sleep disturbances over time. To study the effects of repeated low‐level blast injury (rLLB), we developed a mouse model exposed to <10 psi shock waves repeated 24 hours for 5 days. Injured mice developed chronic anxiety‐like symptoms, and short‐term memory impairments over 1 month post injury. Open field test revealed that the sham mice spent 200.9 ± 18.8 sec in center zone while rLLB mice spent 104.0 ± 10.7 sec in center zone. In the novel object recognition test, sham mice showed more interest in a new object (discrimination index 0.62 ± 0.02) while the rLLB injured mice spent equal time on the new and old object (discrimination index 0.50 ± 0.02). In the elevated plus maze test, sham mice entered open arm zone 14.7 ± 2.4 times while rLLB injured mice entered open arm zone 7.6 ± 1.7 times. The sham mice spent 30.1 ± 3.5 sec in open arm zone while the rLLB injured mice spent 20.2 ± 3.1 sec in open arm zone. Sacrificed animals will undergo pathological analysis of associated chronic inflammation. rLLB induces chronic neurobehavioral changes which strongly suggest that repeated blast causes cumulative damage to brain regions and, in doing so, may be responsible for neurobehavioral alterations.
Keywords: Behavioral Function, Blast, Biomechanics
NEUROBEHAVIORAL AND PHYSIOLOGICAL EFFECTS OF TRAUMATIC BRAIN INJURY IN SPONTANEOUSLY HYPERTENSIVE RATS
1Safar Center for Resuscitation Research, Pittsburgh PA, United States, 2UPMC Department of Physical Medicine and Rehabilitation, Pittsburgh PA, United States
Keywords: Behavioral Function, Cognition/Learning/Memory, Aging, Executive Function
NEURAL NETWORK CLASSIFICATION OF BARNES MAZE SEARCH STRATEGY UTILIZATION
1Roskamp Institute, Sarasota FL, United States
The Barnes maze is a hippocampal‐dependent spatial learning and memory task involving a circular table with holes positioned around the perimeter originally developed for rats and later adapter for mice. Spatial cues located around the walls of the room allow the animal to orient themselves and locate a target box hidden beneath a hole at the perimeter of an elevated table. The outcome measures evaluated typically include the frequency of nose poke errors, both primary (errors made before the first poke in the target hole) and total (total frequency of errors), as well as the frequency of target hole nose pokes, and the latency to the first target hole nose poke. The Barnes maze itself is intended to evaluate spatial learning and memory, and while these outcome measures can each serve as a proxy to detecting differences in spatial learning and memory, directly quantifying search strategy utilization has gained popularity in recent years. This is typically done by a trained blinded observer who is manually categorizing trials or portions of trials as spatial, serial (non‐spatial systematic searching), or random in their search strategies. We present here the development and use of an artificial recurrent neural network (RNN) to perform continuous automatic and blinded categorization and quantification of the search strategies used by mice in the Barnes maze.
Keywords: Behavioral Function, Concussion/mTBI, Computational/Modeling
FUNCTIONAL IMPAIRMENT IS ASSOCIATED WITH LONG‐TERM LIFE SATISFACTION IN VETERANS WITH MTBI
1Department of Psychology, University of Texas San Antonio, San Antonio TX, United States, 2Polytrauma Rehabilitation Center, South Texas Veterans Health Care System, San Antonio TX, United States
Keywords: Post‐Traumatic Stress, Concussion/mTBI
TRANSCRANIAL DIRECT‐CURRENT STIMULATION AFTER BRAIN INJURY DOES NOT IMPROVE IMPULSIVITY OR RISKY DECISION‐MAKING DEFICITS IN MALE AND FEMALE RATS
1The Ohio State University, Columbus OH, United States
Traumatic brain injury (TBI) often results in chronic deficits in decision‐making and impulsivity. Impaired dopamine signaling is a potential contributor to these impairments and may be recovered by cathodal transcranial direct current stimulation (tDCS). Therefore, it may be an effective treatment strategy for long‐term cognitive deficits in patients with TBI. The purpose of this study was to determine how TBI affected female rats' decision‐making and impulsivity compared to male rats and to evaluate if tDCS could treat such deficits. Rats were trained on the Rodent Gambling Task (RGT) which measures risk‐based decision‐making and motor impulsivity. During the task, rats chose between options of varying probabilities and magnitudes of reinforcement and punishment. Once responding stabilized, rats were given a bilateral frontal controlled cortical impact injury. After establishing a new baseline of responding following injury (7 weeks), tDCS (cathodal, 10 min, 800 μA) was delivered two hours prior to testing for seven days in a cross‐over design. Though there were minimal baseline sex differences, brain injury similarly increased impulsivity and impaired decision‐making. tDCS did not improve these symptoms in sham or TBI rats. While disappointing, these results will help to determine effective treatment strategies for both males and female.
Keywords: Behavioral Function, Executive Function
THE EFFECTS OF LATERAL FLUID PERCUSSION INJURY AND DEEP BRAIN STIMULATION ON HIPPOCAMPAL NETWORK OSCILLATIONS
1University Of California Davis, Davis CA, United States
Our lab has demonstrated that short (1‐5min) and extended epochs (30min) of theta frequency deep brain stimulation (DBS) of the medial septal nucleus (MSN) improve cognitive outcomes in the weeks following lateral fluid percussion injury. Additionally, DBS delivered during the subacute period (post injury days; PID3‐7) results in maximal benefits as compared to acute (PID0‐4) and delayed (PID8‐12) stimulation. We hypothesize that behavioral changes will be related to altered network oscillations, and that stimulation will restore more physiologic activity.
Male Sprague‐Dawley rats underwent sham (n = 11) or TBI (n = 41). Bipolar stimulating electrodes were implanted in the MSN and bilateral recording electrodes in the dorsal hippocampus (dHPC), MSN, and prefrontal cortex (PFC). Injured animals received either no stimulation (n = 10), ACUTE (PID0‐4; n = 11), SUBACUTE (PID3‐7; n = 10), or DELAYED (PID8‐12; n = 10) stimulation (7.7Hz, 80uA, 30min/day). Local fields were recorded on PID1, 7, 12 as well as before, during, and after each stimulation epoch.
Ipsilateral neural activity was significantly reduced on PID1 and 7 in dHPC, but only on PID1 in the MSN and PFC as compared to sham (p < 0.05). Contralaterally, power was only reduced on PID1 in the dHPC, but was reduced on PID1 and 7 in the PFC (p < 0.05). Counter to our hypothesis, 30‐minutes of stimulation significantly suppressed local fields for at least one hour but less than 24‐hours (p < 0.05). This was evident in both brain hemispheres and across regions.
Keywords: Cognition/Learning/Memory, Electrophysiology
ANALYSIS OF CORTICAL SPREADING DEPOLARIZATIONS IN A RODENT MODEL OF TRAUMATIC BRAIN INJURY
1University of Cincinnati, Cincinnati OH, United States, 2Department of Neurosurgery, University of Cincinnati, Cincinnati OH, United States, 3Neurotrauma Center, University of Cincinnati Gardner Neuroscience Institute, Cincinnati OH, United States
Cortical spreading depolarizations (CSDs) are waves of mass depolarization that travel through the gray matter of the brain and cause near‐complete loss of ion homeostasis. CSDs occur in more than half of patients with moderate/severe traumatic brain injuries (TBIs) and are associated with worse outcomes. We investigated the consequences of CSDs in an experimental model of TBI. Adult Long Evans rats were subjected to either a moderate lateral fluid percussion injury (LFPI) or a sham injury. Within 2 hours of injury or sham, saline (control) was applied to the cortex, or CSDs were induced every 15 minutes with 1M potassium chloride (KCl). Electrocorticographic activity was recorded for 2 hours. Four days after injury or sham, animals were injected with 2 doses of 100mg/kg bromodeoxyuridine (BrdU) at 6‐hour intervals. Tissue was collected 2 weeks after injury or sham, and ipsilateral dentate gyrus was evaluated for newly generated neurons. A total of 36 SDs were induced in the sham group and 33 SDs were induced in the TBI group. The TBI+CSD group had longer average duration of depolarization (p = 0.0019). Total number of BrdU+ nuclei in the dentate gyrus was significantly increased in TBI+CSD animals (p = 0.0373). Total number of new immature (BrdU+/DCX+) neurons was significantly increased in TBI+CSD animals (p = 0.0174). Our study revealed electrophysiologic and neurogenesis differences between TBI and sham animals subjected to CSDs.
Keywords: Secondary Injury, Electrophysiology, Neurogenesis
ASTROCYTES SHOW MULTIPLE ALTERATIONS AFTER TBI AS REVEALED BY GFAP AND AQ4
1Uniformed Services University Of The Health Sciences, Bethesda MD, United States, 2Anatomy, Physiology and Genetics, Bethesda MD, United States, 3Molecular and Cellular Biology, Bethesda MD, United States, 4Center for Neuroscience and Regenerative Medicine, Bethesda MD, United States
The impact of modern warfare correlates with increases in US military personnel experiencing traumatic brain injuries (TBI), which impact individuals' ability to function long after the primary injury. Our laboratory designed an injury model mimicking combat trauma consisting of multiple blasts (using an advanced blast simulator) and CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration) insults with and without stress, to reveal the details of persistent neurobiological alterations, at 4‐weeks and 6‐months post injury. To enhance translational ability, we used ferrets ‐ the smallest mammal with a gyrencephalic cortex. The glymphatic pathway, a recently described mechanism with a role in neural toxin clearance, may be impacted after TBI, because of abnormal protein aggregation (such as phosphorylated tau) often associated with neurodegenerative diseases. Astrocytes influence the function of the glymphatic pathway by contributing to the exchange of fluids and removal of toxins. To assess the impact of astrocytes in this model, we evaluated the immunoreactivity of glial fibrillary acidic protein (GFAP) and aquaporin‐4 (AQ4). GFAP labels the astrocytic soma and processes, while AQ4 is immunoreactive for astrocytic end feet, which surround blood vessels. Quantification of the immunofluorescence (for GFAP and AQ4) in the frontal cortex reveals significant increases in both area and intensity after TBI. Simple Neurite Tracing techniques applied to astrocytes show increased complexity when measuring lengths and total primary branches after TBI, compared to controls. These results emphasize changes in astrocytic components after TBI, which may influence the function of the glymphatic system.
Keywords: Astrocyte, Blast, Blood Brain Barrier, Imaging, Concussion/mTBI
BRAIN ARCHITECTURE TYPES EXPERIENCE DIFFERENTIAL RESPONSE TO STRUCTURAL LESIONS FROM SIMULATED IMPACTS
1Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville VA, United States, 2Department of Bioengineering, University of Pennsylvania, Philadelphia PA, United States, 3Department of Neurosurgery, University of Pennsylvania, Philadelphia PA, United States, 4Department of Biomedical Engineering, University of Virginia, Charlottesville VA, United States
While angular head kinematics and brain deformation during impact are correlated with traumatic brain injury likelihood, the disparate outcomes among populations that experience similar impact conditions remain unexplained. Herein, we leveraged the structural connectivity (SC) networks of 1,065 brains from the Human Connectome Project (HCP) to simulate the network effects of injury among a population. First, we identified two significantly different brain types according to their SC architectures that experienced differential responses to impacts. Healthy Group 1 networks were characterized by significantly lower global efficiencies, clustering coefficients, and mean betweenness centralities than those in Group 2 (p < 0.05). Then, we used the 50th percentile male Global Human Body Model Consortium (GHBMC) finite element brain model to simulate approximately 1,600 automotive and sports head impact simulations. Using regional strains predicted in each simulation case, we lesioned the edges of each SC network according to the fraction of corresponding elements that experienced maximum principal strains above 15%. To quantify the extent of network disruption, we computed a cosine distance between the healthy and lesioned SC networks. In 32% of the simulated impact cases, lesioned Group 1 exhibited significantly more disruption to the SC network than did lesioned Group 2; in 19% of cases, Group 2 networks were significantly more disrupted (p < 0.05; Bonferroni corrected). For the remaining 49% of cases, no significant difference in SC disruption was predicted. This analysis suggests that network response to lesions is sensitive to both brain architecture type and the strain distributions produced from impact.
Keywords: Computational/Modeling, Biomechanics, White Matter
MODERATE/SEVERE TRAUMATIC BRAIN INJURY ACCELERATES NORMAL BRAIN AGING
1University Of Utah, Salt Lake City UT, United States, 2Thompson Institute, University of the Sunshine Coast, Birtinya, Australia, 3Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran, 4Imaging Genetics Center, Stevens Neuroimaging & Informatics Institute, Keck School of Medicine of USC, Marina del Rey CA, USA, 5Rehabilitation Department, VA Palo Alto, Palo Alto CA, USA, 6Cognitive Neuroscience Unit, School of Psychology, Deakin University, Melbourne, Australia, 7Department of Rehabilitation Medicine, Icahn School of Medicine at Mount Sinai, New York NY, USA, 8Center for Traumatic Brain Injury, Kessler Foundation, East Hanover, USA, 9Cognitive Neuroscience Laboratory, Shirley Ryan AbilityLab, Chicago IL, USA, 10Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway, 11Department of Psychology, Penn State University, State College PA, USA, 12Leonard Davis School of Gerontology, University of Southern California, Los Angeles CA, USA, 13University of Pittsburgh, Departments of Critical Care Medicine, Neurology, Neurological Surgery, Pittsburgh PA, USA, 14Department of Psychology, UCLA, Los Angeles CA, USA, 15H. Ben Taub Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston TX, USA, 16Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway, 17Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Melbourne, Australia
Traumatic brain injury (TBI) can have lifelong consequences for brain health, but exactly how injury influences the normal aging processes is unclear. We leverage data from five cohorts participating in the ENIGMA Adult Mod/Sev TBI working group, some of which are multi‐site projects. A total of 651 participants (405 TBI/246 comparison, 499 M/152 F, age 49.7 ± 18.4 years,age range 17‐85 years) were included. Participants with TBI were scanned with a mean post‐injury interval of 16.1 ± 18.2 years (range = 2 months‐66 years). Brain age was estimated using BrainAgeR (
Keywords: Secondary Injury, Aging, Imaging, Computational/Modeling
ASSOCIATION OF INTRAVENTRICULAR FIBRINOLYSIS WITH CLINICAL OUTCOMES IN PATIENTS WITH INTRACEREBRAL HEMORRHAGE: AN INDIVIDUAL PARTICIPANT DATA META‐ANALYSIS
1University Hospital Erlangen, Erlangen, Germany
Keywords: Hemorrhage, Neurocritical Care
THE ASSOCIATION OF FUNCTIONAL IMPAIRMENT AND LIFE SATISFACTION AMONG VETERANS WITH MILD TRAUMATIC BRAIN INJURY
1The University Of Texas At San Antonio, San Antonio TX, United States, 2South Texas Veterans Health Care System, San Antonio TX, United States
Keywords: Rehabilitation, Behavioral Function, Post‐Traumatic Stress, Concussion/mTBI, Attention
TRANSLATIONAL OUTCOMES PROJECT IN NEUROTRAUMA (TOP‐NT): DATA SHARING AND ANALYTICS OVERVIEW
1UCSF Brain and Spinal Injury Center, Department of Neurological Surgery, San Francisco CA, United States, 2San Francisco VA Healthcare System, San Francisco CA, United States, 3UCLA, Los Angeles CA, United States, 4University of Florida, Gainesville GA, United States, 5Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore MD, United States, 6Department of Radiology, Johns Hopkins University,, Baltimore MD, United States, 7Georgetown University, Washington, United States, 8Uniformed Services University, Bethesda MD, United States
The Translational Outcomes Program for NeuroTrauma (TOP‐NT) is an NINDS cooperative agreement for developing reproducible TBI biomarkers and data standards that make preclinical data findable, accessible, interoperable, and reusable (FAIR). Four centers (GU/USU, JHU, UCLA, UF) are collecting data using multiple rat TBI models. UCSF supports data sharing/publication/citation and analytics. Here, we provide an overview of the data organization and analytical strategies developed for addressing the difficulties associated with TBI animal data. TOP‐NT established cross‐laboratory standard operating procedures (SOPs) and project‐related common data elements (Wanner et al., NNS2022). Open Data Commons for TBI (odc‐tbi.org), an online data repository for preclinical TBI research with privacy‐controlled data sharing, houses the TOP‐NT consortium datasets. Currently, there are 21 TOP‐NT datasets containing n = 2016 subjects uploaded, and these datasets will be made public and citable with digital object identifiers (DOIs), adhering to the NIH 2023 data sharing policy. We have developed a pipeline for the generation of information (content, type of variables) and statistics (quartiles, deviations, outliers, missing values) to alert those utilizing the dataset to characteristics important for analysis (variable types, missingness). UCSF has begun multidimensional analyses on a portion of these data (Radabaugh et al., NNS2022). TOP‐NT represents a successful example of multicenter, preclinical research that has generated valuable data for both primary analysis by the TOP‐NT centers and secondary analyses by the entire neurotrauma community. Qualified researchers can sign up to access and reuse these data at odc‐tbi.org, as long as the data creators are credited.
Keywords: Biomarker, Behavioral Function, Astrocyte, Imaging, Axonal Injury, Neural Engineering, Concussion/mTBI, Synaptic Function, Electrophysiology, Computational/Modeling, Informatics, White Matter
THE INTRASPINAL ADAPTIVE IMMUNE RESPONSE IN PIGS VARIES BETWEEN MALES AND FEMALES AFTER SPINAL CORD INJURY
1Spinal Cord and Brain Injury Research Center and Department of Physiology, University Of Kentucky, Lexington KY, United States, 2University of Utah, Salt Lake City UT, United States
The incidence of spinal cord injury (SCI) among females is increasing, however, sex is understudied in SCI pathophysiology. Further, responses in rodents may not predict human conditions. Here, we examined intraspinal inflammatory responses between male and female pigs after T10 contusion injury. The pig SCI model has important similarities to humans in anatomic and physiologic characteristics including inflammation. Briefly, adult (gonad‐intact) male and female Yucatan miniature swine were subjected to either a SCI or laminectomy only control. Females were injured on proestrus, estrus and diestrus stages to consider the effects of estrous cycle. Animals were sacrificed at 48hr or 6 weeks after SCI and spinal cord sections analyzed for astrocytes, microglia, macrophages, and T‐lymphocytes (T cells) by immunohistochemistry. Neutrophils were counted based on H&E morphology. No histopathological abnormalities were identified in control cases. All data was analyzed on Halo v2.2.1870. No differences were seen for astrocytes, microglia, macrophages and neutrophil infiltration between males and females. Individual intraspinal T cell counts and T cell microclusters were significantly higher in females (independent of estrus stage) and in females injured at proestrus (in case of T cell counts only) compared to males by Welch's t test. Our observation indicates that sex is a potential biological variable for T cell infiltration and may contribute to difference in sex‐based differences in SCI pathophysiology and recovery outcomes. The adaptive immune response is implicated in a number of SCI complications (pain, autoimmunity, neural repair); our data implicates sex as a potential factor for immune‐focused SCI therapies.
Keywords: Neuroprotection, Secondary Injury, Pain, Inflammation/Immune Function, Neuropathology
NOVEL BIOMARKERS WITHIN EXTRACELLULAR VESICLES FOR THE IDENTIFICATION OF TRAUMATIC BRAIN INJURY SEVERITY
1Department of Ophthalmology and Visual Sciences, University of Texas Medical Branch at Galveston, Galveston TX, United States, 2Department of Cancer Biology, The University of Kansas Medical Center, Kansas City MO, United States, 3Department of Anesthesiology, University of Texas Medical Branch at Galveston, Galveston TX, United States, 4Neuroscience Graduate Program, University of Texas Medical Branch at Galveston, Galveston TX, United States
The current diagnosis of TBI include a neurological exam such as Glasgow Coma Scale (GCS) and imaging tests (CT, MRI) that are time consuming and require dedicated resources that are not readily available in resource‐challenged environments such as emergency rooms, sports arenas, and battlefields. Thus, there is an urgent need for the rapid identification of novel biomarkers in liquid biopsies for an early detection and quantitative monitoring of TBI severity. Based on our preliminary data and recently published study, we propose that amounts of circulating cell free DNA (ccf‐DNA) particularly of mitochondrial origin and brain‐type specific markers, present in circulating extracellular vesicles (EV's), represent a novel class of biomarkers for TBI. In this project, we subjected 8–10‐week‐old C57BL6 male mice to mild TBI using the closed head weight drop model followed by isolation of blood plasma at several time points post injury. We have characterized the number and size distribution of EV's post injury, together with the origin and amount of ccf‐DNA released in the EV's. Furthermore, we have performed proteomic analysis of isolated EVs and discovered several novel protein biomarkers that are both up‐ and downregulated across various time points post‐injury. Our findings suggest ccf‐DNA, along with EVs' biomarkers, could potentially be used as diagnostic tools for the rapid, accurate assessment of TBI occurrence and severity.
Keywords: Biomarker, Blood Brain Barrier, Concussion/mTBI, Diagnostics
SEX‐SPECIFIC VARIATION OF CATECHOLAMINE REGULATORY PROTEINS MAY UNDERLIE INCREASED RISKY CHOICE PREFERENCE FOLLOWING REPETITIVE MILD TRAUMATIC BRAIN INJURY
1Rowan University Graduate School of Biomedical Sciences, Stratford CT, United States, 2University of British Columbia, Vancouver, Canada
Mild traumatic brain injury (mTBI) can disrupt cognitive processes leading to increased risk‐taking behavior. Little is known how repetitive injury (rmTBI) affects risky choices or whether these outcomes are sex‐specific. Here we examined how rmTBI affects risk/reward behavior in rodents using a well‐established probabilistic discounting task (PDT). Rats were trained in the PDT, exposed to a single or a series of 3 closed‐head control cortical impact injuries within 1 week, and then tested for 4 weeks. RmTBI increased risky choice in females, but not males, during the first two weeks post‐injury. This behavior normalized by week 3 indicating that these effects are transient. The medial (mPFC), orbitofrontal (OFC), and anterior cingulate (ACC) regions of the PFC play prominent roles in risk/reward decision making. Previous reports have demonstrated catecholamine imbalances within the PFC following TBI, which may underlie TBI‐induced behavioral outcomes. To investigate potential mechanisms of catecholamine imbalance, Western blotting was used to measure levels of the packaging enzyme, VMAT2, and degradation enzymes, COMT and MAO‐A, in PFC sub‐regions following injury. VMAT2 and COMT were reduced in the OFC of rmTBI males and females, while MAO‐A was only reduced in the OFC of rmTBI females. These results indicate a lower capacity for packaging and release, and a decreased need for degradation. This sex‐specific decrease of MAO‐A serves as a novel variable to further elucidate differential rmTBI‐induced mechanisms of increased risk preference. Funding sources: New Jersey Commission on Brain Injury Research CBIR20PIL004 and CBIR19IRG025, and Osteopathic Heritage Foundation for Primary Care Research.
Keywords: Behavioral Function, Neurotransmitter, Executive Function, Concussion/mTBI
REDUCED PLASMA GLIAL FIBRILLARY ACID PROTEIN CORRELATES WITH POOR SLEEP QUALITY IN WARFIGHTERS WITH MILD TRAUMATIC BRAIN INJURY
1School of Medicine , Bethesda MD, United States, 2Center for Neurosciences and Regenerative Medicine, Bethesda MD, United States, 3CENC Biorepository, Bethesda MD, United States, 4School of Nursing and School of Medicine, Baltimore MD, United States
Keywords: Biomarker, Sleep, Blast, Concussion/mTBI
SUBCONCUSSIVE HEAD IMPACTS CONFER POSSIBLE PARAHIPPOCAMPAL PROTECTION IN MICE
1University of Pennsylvania, Philadelphia PA, United States
Subconcussive head impacts (SHIs) are defined as impacts that produce no immediate neurocognitive deficit. Although highly pervasive in contact sports, SHIs have an uncertain effect on concussion outcomes. Human studies investigating SHIs' effect on concussion risk and outcome are largely inconclusive, likely due to uncontrollable variability in both subjects and the impacts they experience. Preclinical models examining the neural and glial response to controlled subthreshold loading suggest that impact timing is a key modulator of concussion outcome after SHIs. In this study, we examine the effect of short (1 minute) and long (24 hour) inter‐impact interval (III) subconcussive preconditioning on mouse cognition. For each III, we deliver 3 total impacts, two subconcussive and one concussive, using closed‐head mild CCI. Subconcussive preconditioning with short III, but not long III, may rescue novel object recognition (NOR) (p = 0.10 ‐ short III vs concussion; p > 0.99 ‐ short III vs sham; p = 0.98 ‐ long III vs concussion; p = 0.85 ‐ long III vs sham), suggesting protection of parahippocampal function. In contrast, we find that subconcussive preconditioning has no effect on contextual fear conditioning (CFC) (p = 0.96 ‐ short III vs concussion; p = 0.29 ‐ short III vs sham; p = 0.61 ‐ long III vs concussion; p = 0.96 ‐ long III vs sham), suggesting no protection of hippocampal functioning. Future work will focus on examining the neural and glial changes that subconcussive preconditioning induces to produce this protective effect.
Keywords: Neuroprotection, Behavioral Function
NOVEL DRUG COCKTAIL THERAPY ATTENUATES POST‐TRAUMATIC HYDROCEPHALUS IN A PRECLINICAL MODEL
1Johns Hopkins University of School of Medicine, Baltimore MD, United States
Post‐traumatic hydrocephalus (PTH), a serious and common complication of traumatic brain injury (TBI), is characterized by ongoing chronic inflammation. PTH typically develops over a period of several weeks post‐injury and requires shunt insertion. This interval between the TBI and PTH provides a window of opportunity for therapeutic intervention to prevent a permanent shunt. We hypothesized that neuroimmunomodulation could treat PTH by restoring ventricular homeostasis, attenuating inflammation and improving function. Based on prior work, we chose to test cocktail therapy with roxadustat (ROX), a member of a new class of oral prolyl hydroxylase domain inhibitors, plus high dose melatonin (MLT). To induce PTH secondary to systemic inflammation and TBI, young adult rats received LPS (3mg/kg, ip) or saline on postnatal day 21 (P21) and P23. On P25, rats of both injury groups underwent TBI via impact. Injured rats of both sexes were then randomly allocated to ROX (10mg/kg) plus MLT(20mg/kg) or saline vehicle (P26‐P36). Rats with PTH treated with vehicle developed ventriculomegaly and elevated intracranial pressure (p < 0.05). Treatment with ROX+MLT attenuated increases in intracranial pressure, stabilized glymphatic flow, normalized brain diffusion metrics on diffusion tensor imaging and mitigated gait deficits in PTH animals (p < 0.05). ROX+MLT attenuated deficits in stance, posture, and paw placement and increased fractional anisotropy in white matter tracts (all p < 0.05). In conclusion, the chronic inflammatory state present in after PTH may suppress spontaneous neurological recovery and propagate development of PTH. Neuroimmunomodulation with a cocktail after TBI may provide a clinically‐viable therapeutic strategy to treat individuals suffering from PTH.
Keywords: Neuroprotection, Cerebrospinal Fluid, Inflammation/Immune Function
LONG‐TERM T‐CELL DYSFUNCTION AND DISRUPTION OF CSF DYNAMICS IN POSTHEMORRHAGIC HYDROCEPHALUS
Dr. Shenandoah Robinson1,
1Johns Hopkins University of School of Medicine, Baltimore MD, United States
Acquired hydrocephalus, elevated intracranial pressure from abnormal accumulation of cerebrospinal fluid (CSF), commonly occurs in adults after intraventricular hemorrhage (IVH) and subarachnoid hemorrhage (SAH). Post‐hemorrhagic hydrocephalus (PHH) can be life‐threatening, and treatment typically requires CSF diversion with a shunt. Shunts predispose patients to a lifelong risk of unpredictable malfunction and infection, an impractical and burdensome treatment strategy for most individuals. Here, we tested the hypothesis that sustained inflammation induced from hemoglobin metabolites after IVH preclude the recovery of multiple neural cell types essential to efficient CSF dynamics, including CSF secretion, propulsion and reabsorption. To induce PHH secondary to systemic inflammation and IVH, young adult rats of both sexes were given 3mg/kg LPS (i.p.) or saline control on postnatal day (P)21 and P23. On P25, 50 μl of littermate lysed red blood cells were injected into each lateral ventricle. Results show IVH in the setting of systemic inflammation yields ventriculomegaly and elevated intracranial pressure (n = 10‐13, p < 0.05), concomitant with microstructural brain injury observed on diffusion tensor imaging and glymphatic disturbance. Multiparameter flow cytometry revealed T cell subpopulations are significantly altered in animals with PHH, including an increase in activated CD25(lo)/CD8(hi) T cells, and a reduction in anti‐ inflammatory CD25(lo)Foxp3(hi) T‐cells (p < 0.01). These maladaptive changes in T cells were associated with cilia and choroid plexus inflammation (all p < 0.05). Taken together, chronic inflammation after PHH persists through adulthood and alters CSF dynamics and ventricular homeostasis. These results support the use of immunomodulatory therapies to normalize the altered cellular inflammatory pathophysiology that propagates acquired hydrocephalus.
Keywords: Cerebrospinal Fluid, Hemorrhage, Inflammation/Immune Function, Neuropathology
TREATMENT WITH THE 5‐HYDROXYTRYPTAMINE 1F RECEPTOR AGONIST LASMIDITAN POST‐SCI UPREGULATES MITOCHONDRIAL SIRTUIN ACTIVITY
1Department of Pharmacology & Toxicology, College of Pharmacy, University Of Arizona, Tucson AZ, United States, 2Southern Arizona VA Health Care System, Tucson AZ, United States, 3Southwest Environmental Health Science Center, University of Arizona, Tucson AZ, United States, 4Center for Innovation in Brain Science, University of Arizona, Tucson AZ, United States
Spinal cord injury (SCI) decreases oxygen delivery throughout the cord, resulting in a cascade of secondary injuries, including mitochondrial dysfunction. Treatment with the FDA‐approved 5‐hydroxytryptamine 1F (5‐HT1F) receptor agonist lasmiditan induces mitochondrial biogenesis (MB) in the spinal cord and improves locomotor function following SCI. However, the mechanism of lasmiditan‐induced recovery remains unknown. Sirtuins (SIRTs) play vast roles within the CNS, with mitochondrial SIRTs, including SIRT3, having neuroprotective effects. SIRT3 is involved in the deacetylation and activation of mitochondrial proteins, meaning decreased SIRT3 activity can lead to decreased mitochondrial function. Additionally, SIRT3 is downstream of PGC‐1α, the “master regulator” of MB. To investigate the role of SIRT3 in lasmiditan‐induced MB and recovery post‐SCI, female C57bl/6j mice were subjected to severe thoracic injury (80 kdyn) followed by daily treatment with vehicle or 0.1 mg/kg lasmiditan (i.p) beginning 1h post‐SCI. We observed SIRT3 downregulation 3 DPI in the injury site of injured mice, correlating with mitochondrial dysfunction. By 7 DPI, lasmiditan‐treated mice had increased PGC‐1α, mitochondrial transcription factor A (TFAM), and SIRT3 at the injury site compared to vehicle‐treated and sham groups. Based on these data, mitochondrial protein lysate was used to measure SIRT3 deacetylation activity at 7 DPI. Similar to increases in PGC‐1, TFAM and SIRT3, SIRT3 deacetylation activity was upregulated 1.4‐fold in lasmiditan‐treated mice compared to sham controls. We suggest a role for mitochondrial SIRT3 activity in lasmiditan‐induced recovery post‐SCI.
Keywords: Secondary Injury, Gene Expression, Receptor Mediated/Signaling, Metabolism/Energetics
DISCONNECTING BRAIN REGIONS INTEGRAL TO STRUCTURAL PATHS FROM THE HIPPOCAMPUS ALTERS SIMULATED FUNCTIONAL CONNECTIONS FOR AN IN SILICO MOUSE BRAIN NETWORK MODEL
1University Of Pennsylvania, Philadelphia PA, United States, 2University of Virginia, Charlottesville VA, United States
At least 15% of concussion patients experience persistent cognitive impairments, the causes of which remain unclear. Structural brain imaging of concussion patients shows that damage to white matter connections between brain regions may differ for patients with persistent symptoms relative to those patients without impairments. Functional brain imaging also reveals altered connectivity patterns in concussion patients which may develop as a consequence of damage to the white matter network, and these altered functional connectivity patterns have been associated with impairments. There is a need to experimentally test the consequences of structural brain network damage on function. To predict the functional effects of local brain injuries in an animal model, we generate a 426‐node mouse brain network model in silico from directed structural connectivity data and simulate brain activity using a simplified dynamical model, the Kuramoto model. To focus on changes which may affect hippocampal function in vivo, we individually disconnect 38 nodes which possess strong structural connections with hippocampal regions or support the shortest structural paths from hippocampal nodes to other nodes. We find that disconnecting nodes with strong input connections significantly changes the whole brain network's simulated functional connectivity (R = 0.8012, p < 0.01), while disconnecting nodes which are incorporated in the shortest structural paths from hippocampal nodes to other nodes significantly changes the functional connections that involve hippocampal regions (R = 0.5761, p < 0.01). These results identify brain regions which may impair cognition after injury, which can be experimentally tested in vivo.
Keywords: Computational/Modeling, White Matter
POST‐INJURY TIME‐COURSE OF MITOCHONDRIAL OXIDATIVE STRESS AND ANTIOXIDANTS MARKERS FOLLOWING SEVERE PENETRATING TBI
1WRAIR, Silver Spring MD, United States
Oxidative stress is a pathological state when free radicals generation outbalances elimination of these radicals through innate antioxidants system. The injured brain is susceptible to oxidative stress due to its high metabolic demand, and contains high polyunsaturated fatty acids and redox transition metals making it an ideal target for free radicals attack. In the interest of future evaluation of mitochondria targeted neuroprotection drugs, we conducted a time‐course evaluation of oxidative stress and antioxidant markers following penetrating traumatic brain injury (PTBI). Anesthetized adult male Sprague‐Dawley rats (280–350 g) were subjected to either 10% unilateral PTBI or Sham craniectomy, followed by excitotoxic responses evaluated at 30 min, 3h, 6h, 24h, 3d, 7d and 14d (n = 6‐10 animals/group X 7 time‐points). At each‐time point, animals were euthanized and mitochondria isolated from ipsilateral frontal cortex and striatum areas. Both 3‐nitrotyrosine (3‐NT) and protein carbonyl (PC), the hallmarks of free radicals mediated protein modification during oxidative stress resulted in significantly increased expression (14‐53%, vs. Sham) during first 3d time‐points following PTBI. In general, all antioxidants such as glutathione (GSH), peroxiredoxins (PRX‐3), thioredoxins (TRX), nicotinamide adenine dinucleotide phosphate (NADPH) and superoxide dismutase (SOD) expression/level were significantly decreased (20‐80%, vs. Sham), whereas the catalase (CAT) exhibited increased (45‐75%, vs. Sham) expression during first 7d post‐injury period. Overall, we observed a maximum imbalance of oxidative stress and antioxidant markers during the first week following PTBI. The mitochondria‐targeted acute pathophysiological secondary injury responses should be mitigated by targeted mitochondrial antioxidant therapeutics following PTBI.
Keywords: Excitotoxicity, Neuroprotection, Metabolism/Energetics, Free Radicals
REGIONAL VARIABILITY IN ANNUALIZED RATES OF CORTICAL ATROPHY LEADING TO ACCELERATED BRAIN AGING AFTER MILD TRAUMATIC BRAIN INJURY
Mr. Alexander Maher1, Dr. Anar Amgalan1, Mr. Roy Massett1,
1University Of Southern California, Los Angeles CA, United States
Traumatic brain injury (TBI) is associated with biological brain aging. However, the specific anatomical features and structures explaining TBI‐related brain aging have not been described. To identify these, we undertook systematic regression analyses of anatomic features across 83 cortical and subcortical structures in a cross‐sectional cohort of 3418 healthy controls (HCs, 1853 females, age μ = 53,σ = 19, range = 22‐95) and 259 participants with a single mild TBI (mTBI, 79 females, age μ = 42,σ = 16, range = 20‐86). In 66 of the 83 brain structures studied, mTBI participants exhibited annualized atrophy rates that were both significantly faster (all p < 0.05, corrected) and at least twice as fast as HCs'. The regions with greatest acceleration in annualized atrophy were in the frontal and temporal lobes. In 32 of the 75 74 cortical regions studied, the cortex thinned significantly faster in mTBI (all p < 0.05, corrected). This study provides initial evidence on the region‐specific anatomic profiles of post‐traumatic cortical thinning and atrophy leading to older biological age of the brain. Future studies leveraging such information could further evaluate the extent to which such regional alterations affect mTBI clinical outcome, risk for neurological disease, and mortality.
Keywords: Biomarker, Aging, Concussion/mTBI
DEGENERATION AND COLLATERAL PLASTICITY IN THE MURINE RETINOCOLLICULAR SYSTEM AFTER IMPACT‐ACCELERATION TRAUMATIC BRAIN INJURY
1Johns Hopkins School of Medicine, Department of Pathology, Baltimore MD, United States, 2Johns Hopkins School of Medicine, Department of Neurology, Baltimore MD, United States, 3Johns Hopkins School of Medicine, Department of Psychiatry and Behavioral Sciences, Baltimore MD, United States, 4Johns Hopkins School of Medicine, Department of Ophthalmology, Baltimore MD, United States, 5University of California San Diego, Department of Ophthalmology and Shiley Eye Institute, La Jolla CA, United States
Traumatic axonal injury (TAI) is one of the most common neuropathologies in traumatic brain injury and the cause of significant morbidity due to structural and functional disconnection of diverse neuronal networks. In TAI the axonal segments distal to the injury invariably degenerate due to the action of an axon‐specific “suicide” program termed Wallerian degeneration (WD), while the regenerative capacity of the proximal stumps is limited and does not typically result in reconnection with their target. On the other hand, functional recovery may primarily depend on collateral sprouting of surviving and/or uninjured axons. Although suppression of WD is a promising target for neural repair, it is not known whether it may have a negative impact on collateral plasticity. The murine visual system, and particularly the retinocollicular pathway, is ideal for the study of injury‐induced degeneration and plasticity as it allows the separate study of perikarya, axons and terminal fields. Here we utilize our impact acceleration TBI (IA‐TBI) model in combination with AAV‐mediated axon and synapse tracing strategies in order to characterize injury‐related degeneration and plasticity of the retinocollicular system. Preliminary analysis revealed that IA‐TBI results in a 35% loss of retinocollicular axon terminals and synapses at 7 days, followed by partial recovery at 28 days. Characterizing the time‐course of axonal and synaptic degeneration and plasticity in this model system will be pivotal not only for understanding the responses of the CNS to injury but also for assessing the effect of therapeutic interventions that target axonal degeneration and restoration of neurological function.
Keywords: Neurodegeneration, Axonal Injury, Synaptic Function, Regeneration & Plasticity, Neuropathology, White Matter
TRAUMATIC AXONOPATHY IN SPINAL TRACTS AFTER IMPACT ACCELERATION HEAD INJURY: ULTRASTRUCTURAL OBSERVATIONS AND EVIDENCE OF SARM1‐DEPENDENT AXONAL DEGENERATION
1Johns Hopkins University, Department of Pathology, Baltimore MD, United States, 2Johns Hopkins University, Department of Otolaryngology‐HNS, Baltimore MD, United States, 3Johns Hopkins University, Department of Neurology, Baltimore MD, United States, 4Johns Hopkins University, Department of Psychiatry and Behavioral Sciences, Baltimore MD, United States
Traumatic axonal injury (TAI) is a major cause of neurological impairments following traumatic brain injury (TBI). We and others have suggested that TAI activates a highly conserved program of axonal self‐destruction known as Wallerian degeneration (WD). Here, we utilize our well‐established impact‐acceleration (IA)‐TBI model for the ultrastructural characterization of traumatic axonopathy in white matter tracks traversing the ventral, lateral, and dorsal spinal columns of the mouse; and to further assess the effect of genetic SARM1 deletion on axon degeneration and myelin pathology. In silver‐stained preparations, we found that IA‐TBI results in extensive axonopathy across the rostrocaudal axis of the spinal cord associated with microglial reactivity. At the ultrastructural level, we found that traumatic axonopathy is associated with diverse pathologies, ranging from focal axoskeletal perturbations and splitting of myelin sheath to complete axonal fragmentation. While certain ultrastructural alterations may be specific to the biomechanical insult, other features such axoskeletal dissolution, collapsed myelin figures and ovoids are overlapping those encountered in classical paradigms of WD. Profiles such as excess myelin figures and increased inner‐tongue evaginations are more typical of chronic neuropathies. Stereological analysis of pathological profiles in cervical segments from WT and SARM1 KO mice at 3 and 7 days post IA‐TBI (n = 32) revealed an up to 90% reduction of pathological profiles in SARM1 KO mice. Our findings demonstrate the presence of traumatic axonopathy in diverse CNS tracts traversing the spinal cord after IA TBI and the attenuating effect of SARM1 deletion on acute and subacute axonal and myelin pathology.
Keywords: Neuroprotection, Neurodegeneration, Axonal Injury, Neuronal‐Glial Interactions, Neuropathology, White Matter
PERIPHERAL‐DERIVED MONOCYTES DRIVEN BY EPHA4/TIE2 SIGNALING DICTATE BRAIN INJURY OUTCOME
1Virginia Tech, Blacksburg VA, United States
Peripheral derived monocytes (PDMs) have emerged as key regulators of the neuroinflammatory milieu in many neuropathological disorders, including traumatic brain injury (TBI). Ephrin Type‐A Receptor 4 (EphA4) tyrosine kinase has been implicated in the regulation of neuroinflammation. To assess the role of PDM‐derived EphA4 on TBI outcome, we utilized GFP bone marrow chimeric EphA4‐knockout (+KO BMCs) and wild type (+WT BMCs) and the controlled cortical impact (CCI) injury model. We quantified lesion volume (mm3) on serial coronal sections at 4hr, 1‐ and 3‐days post injury (dpi). We found a significant lesion reduction at 1 and 3 dpi (p < 0.01, n = 5) demonstrating neuroprotection in KO mice. Flow cytometry analysis demonstrated a shift in GFP+ monocytes toward an anti‐inflammatory subpopulation in the ipsilateral cortex of KO mice. This included increased Tie2 expression at the mRNA and protein levels. KO macrophages also showed increased levels of activated phosphoinositide 3‐kinase (PI3K) signaling indicated by increased levels of pPDK1 and pAKT. The use of soluble (s)Tie2‐Fc to block Tie2 shows induction of a pro‐inflammatory gene profile in WT, which is attenuated in KO macrophages. In vivo analysis of Tie2 expression on GFP‐positive infiltrating PDMs show increased Tie2 expression and clustering in the damaged cortex of KO mice. Treatment with Tie2 agonist Vasculotide, an Angiopoietin 1 peptide mimetic, demonstrated neuroprotection in WT CCI‐injured mice at 1 dpi versus vehicle control (p < 0.0001, n = 5). Our findings suggest EphA4 may negatively regulate Tie2 to promote an inflammatory profile and Tie2 may be a therapeutic target for controlling neuroinflammation following TBI.
Keywords: Neuroprotection, Therapeutics/Drug Discovery, Inflammation/Immune Function, Receptor Mediated/Signaling
EARLY URINE BIOMARKERS IN A RODENT MODEL OF MILD TRAUMATIC BRAIN INJURY
1Children's Hospital Of Philadelphia, Philadelphia PA, United States, 2Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, United States, 3Monell Chemical Senses Center, Philadelphia PA, United States
The lack of an objective biomarker hampers mild traumatic brain injury (mTBI) diagnosis and limits the ability to treat and monitor patients. Urine has high potential as a valuable source for a biomarker as it is easily collected, especially for children, and can be distinguished by odor volatiles. Our previous work identified discriminatory volatile metabolites appearing 48 hours after injury in urine of mice with mild lateral fluid percussion injury (mLFPI) and persisting up to two weeks after injury. The objective of this work is to extend this analysis to the acute time period (<48 hours) which is critical to establishing the potential of the urine biomarker for clinical use. We subjected 50 male mice to mLFPI and compared them to 50 surgical shams. Gas chromatography coupled with mass spectrometry was used to analyze urine samples taken from both cohorts at 1, 12‐, 24‐, 48‐, and 96‐hours post‐injury. Analysis of variance was performed on the chromatographic peak responses normalized to a reference standard to investigate the effect of treatment (mLFPI or sham) and time, controlling for false discovery rate. Of the 68 volatiles detected, 10 demonstrated elevated peak responses at 1 hour in the injured animals compared to shams, and five of these compounds were ketones. These volatile metabolites could form the basis for a urine‐based human biomarker of mTBI and greatly improve mTBI diagnosis, monitoring and treatment.
Keywords: Biomarker, Concussion/mTBI
INTRANASAL ADMINISTRATION OF ST266 IN A RODENT MODEL OF TRAUMATIC BRAIN INJURY
1Walter Reed Army Institute of Research, Silver Spring MD, USA, 2Noveome Biotherapeutics, Inc, Pittsburgh PA, USA
ST266 is human amnion‐derived multipotent progenitor cell secretome that is currently being evaluated clinically for ophthalmological/anti‐inflammatory indications and received FDA approval for Phase 1 intranasal nose‐to‐brain study in humans. Intracerebroventricular infusion of ST266 after traumatic brain injury (TBI) has significantly improved motor function and moderated neuroinflammation in rats. However, intracranial administration is not clinically feasible, whereas intranasal drug delivery bypasses the blood brain barrier and limits adverse systemic effects. The current study was designed to test the potential efficacy of intranasal administration of ST266 following severe penetrating TBI (pTBI) in rodents. Adult Sprague‐Dawley rats were subjected to pTBI and received 48μl ST266 or saline delivered in 8μl drops to each nostril. Experimental groups included: (1) sham, (2) pTBI with saline (pTBI+Veh), (3) pTBI with ST266 (pTBI+ST266), and (4) pTBI with a topical bolus of ST266 followed by intranasal delivery (pTBI+Topical). ST266 was administered immediately after brain injury and at 2hr, 6hr, and 24hr post‐injury. Brain tissue from regions of interest were collected for assessment of TNF, IL‐1β, IL‐6, and IFN‐γ. Plasma was collected prior to injury, and at 4h, 24h, and 28h post‐injury for quantification of GFAP, UCH‐L1, NF‐L, and Tau using Quanterix Simoa digital ELISA assay. Intranasal administration of ST266 showed a trend towards reducing inflammatory cytokines in brain tissue. However, ST266 did not ameliorate injury‐induced increases of GFAP, UCH‐L1, NF‐L, and Tau in plasma, which may due to the severity of the injury. Additional work evaluating intranasal administration of ST266 in models of concussion may be warranted.
Keywords: Neuroprotection, Drug Delivery, Therapeutics/Drug Discovery
FDA‐APPROVED HUMAN FETAL‐DERIVED NEURAL STEM CELLS FAIL TO IMPROVE COGNITIVE OR MOTOR OUTCOME IN A RODENT MODEL OF TRAUMATIC BRAIN INJURY
1Walter Reed Army Institute of Research, Silver Spring MD, USA
Penetrating traumatic brain injury (pTBI) inflicts a defined focal injury with neurological impairment. Cellular replacement therapy is a potential restorative strategy. NSI‐566 are a FDA‐approved human neural stem cell (NSC) line with neuronal differentiation capacity used in stroke and spinal cord injury Phase I and II clinical trials. Pre‐clinical studies demonstrated NSI‐566 transplantation mitigates motor dysfunction. This study evaluated the neuroprotective potential of NSI‐566 transplantation into the striatum (STR) or hippocampus (HC) following pTBI. Unilateral pTBI was performed on anesthetized rats. At 7 days post‐injury, NSCs or vehicle (VEH) were injected into STR or HC regions in injured hemisphere as experimental groups: sham, STR‐NSC, STR‐VEH, HC‐NSC, and HC‐VEH. Rotarod testing assessed prior to transplantation (6 days post‐pTBI), 8 and 21 days post‐transplant. Morris water maze tasks performed at 5 and 6 weeks post‐transplant. Significant motor deficits were found in injured groups prior to transplantation (p < 0.05 vs sham); however, this was not true following transplantation, regardless of transplant locations (STR, p = 0.35. HC, p = 0.2). Significant cognitive deficits were found in injured groups vs shams. Transplantation into injured striatal (i.e. perilesional) region nor hippocampus did not yield cognitive benefits. Our results revealed intracerebral targeted treatment with NSI‐566 failed to provide significant therapeutic outcomes regardless of the transplant location. The lack of therapeutic effects for NSC transplantation was unexpected and may preclude continued pre‐clinical research on this cell line for TBI. This work was funded by the U.S. Army Combat Casualty Care Research Program.
Keywords: Neuroprotection, Behavioral Function, Stem Cells, Ballistic Injury
PRELIMINARY PHARMACOKINETIC AND PHARMACODYNAMICS (PK/PD) PROFILE OF PERIPHERALLY ADMINISTRATED ANTI‐CD47 ANTIBODIES IN A RAT MODEL OF PTBI
1Walter Reed Army Institute Of Research, Silver Spring MD, United States
There remains a lack of therapeutic options for traumatic brain injury (TBI)‐induced intracerebral hematoma clearance. CD47 is an anti‐phagocytic cell surface protein involved in hematoma stability. Pre‐clinical stroke models have demonstrated potential for anti‐CD47 antibodies in augmenting hematoma clearance. The objective of this study was to evaluate the pharmacokinetic and pharmacodynamics profile of intravenously (i.v.) administrated anti‐CD47 antibody following TBI, and potential neuroprotective effects. Anti‐CD47 antibody therapy was administered at varying doses intravenously. Blood, urinalysis and extensive diagnostic necropsy were used to evaluate the safety of this antibody. Anti‐CD47 antibody concentration in blood and brain lysates was detected using a customized fluorescence‐based spectrophotometric assay. Neurological assessment, cerebral edema measurement and immunohistochemistry were used to determine efficacy on mitigating TBI‐induced neuropathology. At 2 hrs post‐injury, preliminary results showed that anti‐CD47 antibody was detected in plasma at 10.37 ± 0.36 ug/ml and was still present in plasma at 72 hrs post‐injury at a concentration of 2.41 ± 0.52 ug/ml. In addition, 32 ng/ml (contralateral) and 55 ng/ml (ipsilateral) were detected in brain lysates. Neurological assessment revealed no change in neurological deficits following anti‐CD47 antibody treatment. Blood test and initial necropsy analysis has demonstrated no severe adverse events but additional evaluation is ongoing. These results provide preliminary evidence that peripherally administrated anti‐CD47 antibodies following pTBI did not cause severe adverse events and is well tolerated. While no improvement of neurological deficits was observed, continued analysis of neuropathology will evaluate potential neuroprotective effects and hematoma clearance. This work was supported by Combat Casualty Care Research Program.
Keywords: Neuroprotection, Neuropathology
A NOVEL ANNOTATION TOOL USING MULTIMODALITY NEUROMONITORING DATA SUPERIMPOSED WITH CLINICALLY‐RELEVANT EVENTS FOR MACHINE LEARNING
1Moberg Analytics, Philadelphia PA, United States, 2Drexel University School of Biomedical Engineering, Philadelphia PA, United States, 3IBM Corporation, San Francisco CA, United States, 4Massachusetts General Hospital, Boston MA, United States, 5University of Cincinnati, Cincinnati OH, United States, 6University of Texas Southwestern, Dallas TX, United States
Multimodal neuromonitoring data has been shown to be advantageous in the acute care management of brain‐injured patients. This integrated data is now routinely available from several commercial and research platforms. Missing from all of these systems is the ability to record and time synchronize concurrent therapeutic actions related to the patient. The lack of this data can confound the interpretation of the physiological recordings, particularly when used in downstream machine learning applications.
For these reasons, we have developed a novel annotation tool and display for multimodal neuromonitoring data with an in‐time display of contextual data, such as medication administration, dose changes, and clinical events. It allows the user to interact with this diverse set of metadata and add free‐text or form‐text annotations in a variety of modality configurations.
We performed preliminary feasibility testing with our clinical team whose expertise spans neurocritical care, intensive care nursing, and multimodal neuromonitoring reports. This focus group reported that there are significant advantages to our tool real‐time and post‐time clinical events display compared to traditional multimodality monitors and medical record systems.
This tool serves as a preliminary step toward incorporating important contextual data into downstream machine learning applications.
This work was supported by the Combat Casualty Care Research Program (Award W81XWH‐19‐2‐0013).
Keywords: Monitoring, Informatics
DELETION OF ICAM‐1 USING CRISPR/CAS9 PROTECTS NEUROVASCULAR DAMAGE AFTER TRAUMATIC BRAIN INJURY
1Laboratory of CNS Injury and Molecular Therapy, JFK Neuroscience Institute, Hackensack Meridian Health JFK University Medical Center, Edison NJ, United States
Traumatic brain injury (TBI) causes the blood‐brain barrier (BBB) dysfunction and transmigration of immune cells into the brain, an important mechanism underlying neurovascular damage and neuroinflammation. Intercellular adhesion molecule‐1 (ICAM‐1) is identified as an initiator of neuroinflammatory responses that leads to neurodegeneration and cognitive and sensory‐motor deficits in several pathophysiological conditions. However, the underlying mechanisms of ICAM‐1‐mediated neuroinflammation and neurovascular damage and its link with functional deficits following TBI remains elusive. We hypothesize that deletion of ICAM‐1 using CRISPR/Cas9 technology remodels the neurovascular system and promotes functional recovery after TBI. The experimental TBI was induced in vivo by fluid percussion injury (20 psi) in wild‐type and ICAM‐1‐/‐ mice and in vitro by stretch‐injury (3 psi) in human brain microvascular endothelial cells (hBMVECs). We manipulated ICAM‐1 pharmacologically and genetically and conducted several biochemical analyses to gain insight into the mechanisms underlying ICAM‐1‐mediated transmigration of leukocytes to the brain. We demonstrated the mechanisms of transmigration of blood cells across the BBB due to brain injury and CRISPR/Cas9‐mediated ICAM‐1 deletion mitigates leukocytes transmigration by disrupting the paxillin‐FAK signaling pathway. We used a cohort of behavioral tests that include sensorimotor functions, and psychological stress analyses to test functional outcome upon deletion of ICAM‐1 following TBI. In conclusion, this study could establish the significance of deletion of ICAM‐1 in transforming into a novel preventive approach against the pathophysiology of TBI. This work was supported by New Jersey Commission on Brain Injury Research #CBIR19PIL010 to P.M. Abdul‐Muneer.
Keywords: Behavioral Function, Neurodegeneration, Post‐Traumatic Stress, Blood Brain Barrier
NOVEL CATHETER TECHNOLOGY FOR BURR HOLE EVACUATION OF CHRONIC SUBDURAL HEMATOMA AT THE OPERATIVE ROOM AND BEDSIDE
1University Of Miami, Miami FL, United States
Chronic subdural hematoma (cSDH) burr hole evacuation is a well‐established treatment for symptomatic cases with associated mass effect. Routinely postoperative drain is left in the subdural space to account for residual blood. Drainage obstruction is not rare to occur requiring catheter flushing. The maneuver can be unsuccessful and potentially increase infection risk.
A currently available “anti‐thrombotic” catheter FDA approved for hydrocephalus secondary to hemoventricle was analyzed in our study to mitigate this issue. In this study we studied a new proof of concept. We present the first 14 patients in the literature with cSDH treated with the coated ventricular catheter placed into the subdural space on the operating room or bedside. There was no complication related to the procedure including no related infection. Distal drain obstruction was observed in 2 cases (16.7%), resolved after flushing the system, no proximal obstruction was experienced. The drainage length was 4,7 ± 2,2 days. After 24h of surgery, hematoma width improved in all patients (18.6 ± 7.2mm x 12.7 ± 6.9mm; p < 0.00001; mean volume reduction of 26.3%), as well as midline shift (13.0 ± 7.3mm x 6.7 ± 4.5mm; p < 0.0001). This series shows that this technology can be safely translated for a new indication being effectively used for cSDH burr hole evacuation.
Keywords: Biomaterials, Hemorrhage, Neurocritical Care
DISSOLVING A LARGE ACUTE COMPONENT OF CSDH USING LOCAL RECOMBINANT TISSUE‐TYPE PLASMINOGEN: A CASE REPORT
1University Of Miami, Miami FL, United States
Large acute component in chronic subdural hematoma (cSDH) typically requires craniotomy. Open surgery can be associated to increased morbidity and is not always possible due systemic conditions. We present the dramatic case of a 58 y/o patient that presented with GCS 3 and fixed pupils, with remaining brainstem reflexes present. Brain CT showed a large mixed subdural left chronic hematoma, with predominant acute component, with around 26mm midline shift. The patient was hemodynamically unstable, coagulopathic, thus, emergency burr hole evacuation was done. An “anti‐thrombotic catheter”, originally designed for hemoventricle, was left in the subdural space as postoperative drain. Postoperatively, GCS improved, and CT presented a 13mm midline shift, due to the residual acute bleeding component. Due to patient's poor clinical condition, recombinant tissue‐type plasminogen (r‐tPA) solution was repeatedly administered using the catheter for 2 days. After that, the catheter continued to drain for 10 more days with no additional dose. The patient presented clinical and radiological improvement with near complete dissolution of the acute component. No new hemorrhages or surgical related infection occurred. He started following simple commands after 45 days. This case illustrates the potential role of local therapy using subdural r‐tPA to treat the acute component of cSDH in critically ill patients coupled to an “anti‐thrombotic” catheter.
Keywords: Biomarker, Hemorrhage, Therapeutics/Drug Discovery, Neurocritical Care
D‐SERINE AS POTENTIAL TARGET TO REDUCE SYNAPTIC DAMAGE ON TBI
1University Of Miami, Miami FL, United States
Traumatic brain injury (TBI) results from both inflammatory and non‐inflammatory pathways culminating with progressive cellular loss and synaptic damage. Synaptic damage is one of the most prevalent pathophysiological responses to brain injury and is associated with cognitive, motor and sensory deficits, but is poorly understood. D‐serine is a D‐amino acid that acts as a NMDA receptors (NDMARs) co‐agonist and is a critical mediator of NMDAR‐dependent transmission and synaptic plasticity. In the normal brain, D‐serine is synthetized and released by neurons after conversion from L‐serine by the enzyme serine racemase (SRR). In the pathological TBI hippocampus, we show that glia synthesized D‐serine plays a critical role in synaptic damage after TBI, where both astrocytes and microglia produce and release D‐serine through the Slc1a4 (ASCT1) transporter. In our study we investigated the role of D‐serine in a TBI murine model in and translated the findings to human TBI samples.
Compared to human non‐TBI controls, 12 brain samples from human TBI showed SRR protein level mean increase of 1.6 ± 0.4. Analysis of the D‐serine transporter Slc1a4 showed mean increase of 6.1 ± 1.14 and mRNA ranged mean increase of 3.3 ± 1.7. These findings point to a novel role for glial D‐serine in synaptic damage after TBI, paving the way for the human translation of a potential new pharmacological approach for TBI management.
Keywords: Excitotoxicity, Astrocyte, Neurotransmitter, Synaptic Function
CLEANING UP THE BRAIN AFTER TRAUMA: A NOVEL ROLE FOR EPHA4/STAT6/MERTK SIGNALING IN PERIPHERAL‐DERIVED MACROPHAGES
1Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg VA, United States, 2Center for Engineered Health, Virginia Tech, Blacksburg VA, United States
Neuroinflammation and neuronal apoptosis are hallmarks of traumatic brain injury (TBI). Efferocytosis is a coordinated process that removes apoptotic cell debris and contributes to the resolution of inflammation, however, it's role in TBI remains ill‐defined. Our previous studies demonstrated that EphA4 receptor mediates the pro‐inflammatory peripheral‐derived macrophage (PDM) driven response after trauma. Here, we aimed to characterize efferocytosis, the cell types involved, and evaluate whether PDM‐specific EphA4 restricts this process following TBI. We generated wild‐type (WT) and EphA4‐knockout (KO), GFP+ bone marrow (BM) chimeric mice and performed CCI injury followed by behavioral analysis and histological examination of the damaged cortex. We observed that KO mice displayed improved motor function, reduced cortical cell death as measured by TUNEL, and enhanced efferocytosis efficiency compared to WT mice. The percentage of GFP+/Iba1‐expressing PDMs that engulf NeuN+ or TUNEL+ cells was significantly higher in KO mice (p < 0.05, n = 5). We further performed an in vitro efferocytosis assay using pHrodo‐labeled apoptotic Jurkat cells co‐cultured with GFP+ WT and KO BM‐derived macrophages. We found a significant increase in efferocytosis efficiency in KO compared to WT cells (p < 0.05, n = 4). In addition, mRNA isolated from KO cells show increased expression of the efferocytosis receptor/ligand “eat me” complex MerTK/Gas6 and phospho‐array analysis shows increased p‐Stat6, a key regulator of MerTK/Gas6. Interestingly, the use of Stat6 and MerTK inhibitors attenuated efferocytosis effects in KO macrophages in‐vitro. Our findings implicate the EphA4/Stat6/MerTK axis as a novel regulator of apoptotic debris clearance that may be targeted to augment resolution of inflammation following TBI.
Keywords: Neuroprotection, Cell Death, Inflammation/Immune Function
MICROGLIA AND PERIPHERAL IMMUNE CELLS CONTRIBUTE TO STIMULATOR OF INTERFERON GENES NEUROINFLAMMATORY SIGNALING IN BRAIN INJURY
1Virginia Tech, Blacksburg VA, United States
As a critical component of secondary injury progression in traumatic brain injury (TBI), neuroinflammatory events are highly complex involving both central nervous system‐resident and peripheral immune cells. Using a murine controlled cortical impact (CCI) model, we sought to uncover which cell types controlled the Stimulator of Interferon Genes (STING)‐mediated neuroinflammatory response. Global loss of endogenous STING produced a blunted cytokine response, reduced lesion volume, and resulted in less neuronal cell death compared to wildtype (WT) controls 24 hours after injury (n = 6‐12/genotype). While it has been well‐established that most immune cell types express STING, our data suggests microglia are the primary cell type in the brain expressing STING. To evaluate whether microglia or peripheral immune cells are responsible for catalyzing STING‐mediated neuroinflammation, we utilized transgenic bone marrow (BM) chimeric animals to knockout (KO) STING in either the periphery or brain. When lesion size was assessed 24 hours after TBI, mice lacking STING in either the periphery or brain (WT+KOBM, KO+WTBM) had smaller lesions than their WT chimeric counterparts (WT+WTBM), though they did not fully reach the level of protection seen in the global chimeric STING KO (KO+KOBM) (n = 6‐9/group). However, the chimeric WT+KOBM and KO+WTBM groups had similarly reduced levels of peripheral immune cell infiltration at the site of injury as KO+KOBM controls (n = 4/group). These data suggest that both peripheral and brain‐resident STING signaling contributes to the detrimental neuroinflammatory milieu following TBI. This work was supported by the Commonwealth Health Research Board and NINDS.
Keywords: Secondary Injury, Microglia, Cell Death, Inflammation/Immune Function
CLEARING THROUGH THE SPINAL CORD LESION AFTER INJURY USING IDISCO+
1Department of Biology, Texas A&M University, College Station TX, United States, 2Department of Biomedical Engineering, Texas A&M University, College Station TX, United States, 3Texas A&M Institute for Neuroscience, Texas A&M University, College Station TX, United States
Spinal cord injury (SCI) triggers a diverse array of processes including cell death, inflammation, and scarring. In the sub‐chronic phase of contusion SCI in mice, the injury site typically consists of a dense lesion filled with fibroblasts, macrophages, and extracellular matrix (ECM) components surrounded by layers of reactive astrocytes. We have previously shown that the SCI lesion is resistant to optical tissue clearing when using aqueous‐based techniques, such as the passive CLARITY technique (PACT). The opaque lesion hinders 3D imaging techniques, such as lightsheet microscopy, and prevents the use of tissue clearing for detailed analysis of neural circuit plasticity and sparing following SCI. Organic solved‐based tissue clearing protocols, such as iDISCO+, have been previously shown to clear ECM‐rich tissues. To determine if iDISCO+ could clear through the sub‐chronic SCI lesion, we collected spinal cord tissue at 14 days post‐injury and performed iDISCO+ clearing, including immunolabeling for neuronal soma with NeuN and motor neurons with choline acetyltransferase (ChAT). In this study, iDISCO+ successfully cleared through the lesion site, allowing us to image whole spinal cord tissue, including the lesion site, by lightsheet microscopy. We are currently further optimizing the iDISCO+ protocol as a powerful tool to study neural circuit damage and repair after SCI.
Keywords: Imaging
HYPER‐RAMIFIED MICROGLIA MORPHOLOGY IN PORCINE CORTICAL GRAY MATTER AFTER MILD TRAUMATIC BRAIN INJURY: A NEW CHRONIC PHENOTYPE
1University Of Pennsylvania, Philadelphia PA, United States, 2CMJC VA Medical Center, Philadelphia PA, United States
Traumatic brain injury (TBI) is a major contributor to morbidity and mortality in the United States as several million people visit the emergency department every year due to TBI incidents. Unfortunately, there is still no consensus on the pathology underlying mild TBI, the most common type of TBI. Previous preclinical and post‐mortem human studies have detailed the presence of diffuse axonal injury following TBI, suggesting that white matter pathology is the predominant pathology of diffuse brain injury. However, the inertial loading produced by TBI results in strain fields in both gray and white matter. To further characterize gray matter mild TBI pathology, our lab used a pig model of closed‐head rotational acceleration‐induced TBI to evaluate blood‐brain barrier disruptions, neurodegeneration, and microglia reactivity in the cerebral cortex out to 1 year post‐injury. Immunohistochemical staining revealed an increase in fibrinogen reactivity ‐ a measure of blood‐brain barrier disruption – predominately in the gray matter at 3 days post injury (DPI) which resolved by 7 DPI. Additionally, we observed a hyper‐ramified microglia phenotype – longer processes; more branches, junctions and endpoints ‐ at 30 DPI out to 1 year post injury in discrete cortical regions. Notably, we did not find neuronal loss paired with these chronic microglia changes. Future studies should employ gene expression assays, neuroimaging, and behavioral assays to elucidate the effects of these hyper‐ramified microglia. Further understanding of the brain's inflammatory activity after mild TBI will hopefully provide knowledge of neuronal health that translates to the treatment of TBI in people.
Keywords: Microglia, Blood Brain Barrier, Concussion/mTBI, Inflammation/Immune Function
CHRONIC MICROGLIAL RESPONSES TO TRAUMATIC BRAIN INJURY IN THE AGED BRAIN ARE LINKED WITH APOE
1SBCoA/University Of Kentucky, Lexington KY, United States, 2Department of Neuroscience/University of Kentucky, Lexington KY, United States, 3Department of Physiology/University of Kentucky, Lexington KY, United States
Keywords: Microglia, Aging, Post‐Traumatic Stress, Gene Expression
PURINOMIC‐BASED BIOMARKERS FOR OUTCOME PREDICTION IN SEVERE TBI
1Neurotrauma and Biomarkers Laboratory, Departamento de Bioquímica, Universidade Federal Do Rio Grande Do Sul, Porto Alegre, Brazil, 2Laboratory of Neuroanatomy, Departamento de Ciências Morfológicas, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, 3Neuroinflammation and Neuroimmunology Laboratory, Brain Institute of Rio Grande do Sul, Pontifical Catholic University of Rio Grande do Sul , Porto Alegre, Brazil, 4Department of Anesthesia and Perioperative Medicine, Hospital de Clínicas de Porto Alegre, UFRGS, Porto Alegre, Brazil, 5Department of Anesthesia, Santa Casa de Porto Alegre, Universidade Federal de Ciências Médicas de Porto Alegre, Porto Alegre, Brazil, 6Department of Anesthesia, Hospital Nossa Senhora da Conceição, Porto Alegre, Brazil, 7Programa de Pós‐Graduação em Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Rio Grande, Brazil, 8Penn Center for Brain Injury and Repair and Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia MI, USA
Neurochemical abnormalities are known to underlie high rates of mortality and long‐term disability following severe TBI. Among these, purine‐derivatives have been shown to play important roles in TBI pathogenesis in preclinical models. Nonetheless, very little is known about changes in purine levels and their implications in human TBI. We assessed cerebrospinal fluid (CSF) levels of purines in severe TBI patients as potential biomarkers that predict mortality 3 days following ICU admission and two‐years neurofunctional score using the modified Rankin Scale (mRS). This was a cross‐sectional study performed in 17 severe TBI patients (Glasgow Coma Scale <8) and 51 controls, with registered approval at the local Ethics Committee. Purine levels were compared between control and TBI, and between surviving and non‐surviving patients using Student's t‐test or Mann‐Whitney U test. The mRS follow‐up was correlated with purine levels (Spearman test). Compared to controls, TBI patients presented increased levels of GDP, guanosine, adenosine, inosine, hypoxanthine, and xanthine, with guanosine being associated with improved mRS. Further, GTP, GDP and xanthine levels were increased in surviving, relative to non‐surviving patients. Interestingly, decreased IMP levels were observed in surviving relative to non‐surviving patients, and GTP alone displayed predictive value (AUC = 0.841, p = 0.024) for discriminating survival vs. non‐survival patients up to three days from admission. We highlighted TBI‐specific purine signatures, such as GTP as a sensitive and specific biomarker of mortality, and guanosine as an indicator of long‐term functional disability.
Keywords: Biomarker, Cerebrospinal Fluid, Metabolism/Energetics
BRIDGING ENRICHMENT WITH AMANTADINE AFTER BRAIN TRAUMA IN ADULT MALE RATS
1University of Pittsburgh, Pittsburgh PA, United States
Environmental enrichment (EE) facilitates recovery after traumatic brain injury (TBI). Historically, EE has been provided immediately after TBI, but this approach is not clinically relevant as strenuous rehabilitation is typically not initiated early in TBI patients. However, it is important to begin treating soon after TBI to optimize recovery. Hence, we sought to administer amantadine (AMT) as a bridge therapy before commencing EE. We hypothesized that bridging EE with AMT would result in better neurobehavioral benefits than AMT or EE alone. Anesthetized male rats received a cortical impact or sham injury and then housed in standard (STD) conditions for one week and administered either AMT (10 mg/kg) or saline vehicle (1 mL/kg) intraperitoneally for 7 days (bridge). EE began on day 8 for the bridge and continuous EE groups. Motor and cognition were evaluated. The data showed that EE, whether provided alone or in combination with AMT benefitted both behavioral outcomes (p < 0.05). The AMT bridge plus EE group also recovered behavioral outcomes relative to the STD‐housed groups regardless if given AMT or vehicle (p < 0.05). There was no difference between the AMT bridge and the EE alone groups (p < 0.05), which does not support the hypothesis. Despite not showing an additive benefit, these data show that EE does not have to be implemented immediately after TBI and does not have to be provided continuously to confer benefits after TBI. The lack of an additive effect may be due to the robustness of EE and/or the sub‐optimal dose of AMT.
Keywords: Behavioral Function, Cognition/Learning/Memory, Drug Delivery, Executive Function
DRAG‐REDUCING POLYMERS IMPROVE MICROVASCULAR FLOW AND TISSUE OXYGENATION IN A DOSE‐DEPENDENT MANNER IN MALE AND FEMALE RATS AFTER TBI
Associate Professor Denis Bragin1, Dr. Olga Bragina1, Dr. Marina Kameneva2,
1Lovelace Biomedical Research Institute, Albuquerque NM, United States, 2University of Pittsburgh, Pittsburgh PA, USA, 3Department of Neurology, University of New Mexico School of Medicine, Albuquerque NM, USA
Keywords: Neuroprotection, Secondary Injury, Vascular, Cerebral Blood Flow
NONINVASIVE VAGUS NERVE STIMULATION FOR TREATMENT OF BRAIN INJURY IN RATS
Dr Afshin Divani1, Dr. Yirong Yang1, Dr. Hafiz Abdullha Ikram1, Dr. Pascal Salazar2, Dr. Karen SantaCruz3, Dr. Erik Taylor4,
1Department of Neurology, University of New Mexico School of Medicine,, Albuquerque NM, USA, 2Canon Medical Informatics, Inc., Minnetonka, Minnetonka MN, USA, 3Department of Pathology, University of New Mexico School of Medicine, Albuquerque NM, USA, 4Department of Radiology, University of New Mexico School of Medicine, Albuquerque NM, USA, 5Lovelace Biomedical Research Institute, Albuquerque NM, USA
Keywords: Neuroprotection, Secondary Injury, Imaging, Inflammation/Immune Function
THE OCULAR VERGENCE INDICES DYNAMICS AT MILD‐TO‐MODERATE TBI: PRELIMINARY EYE TRACKING‐BASED STUDY
Dr Alex Trofimov1, Dr. Darya Agarkova1, Dr. Kseniia Trofimova1, Dr. Andrew Abashkin2, Dr. Kyril Lidji‐Goryaev1,
1Department of Neurological Diseases, Privolzhsky Research Medical University, Nizhny , Russia, 2Clinical Emergency Hospital, Dzerzhinsk, Russia, 3Department of Neurology, University of New Mexico School of Medicine, Albuquerque NM, USA, 4Lovelace Biomedical Research Institute, Albuquerque NM, USA
Keywords: Behavioral Function, Monitoring, Concussion/mTBI, Diagnostics, Neurocritical Care
CEREBRAL ISCHEMIA AND CEREBRAL BLOOD FLOW DYSREGULATION IN THE PATHOGENESIS OF TRAUMATIC BRAIN INJURY
1University Of New Mexico, Albuquerque NM, United States
That low cerebral blood flow (CBF) and cerebral ischemia are definitive events in the pathogenesis and outcome after severe traumatic brain injury (sTBI) has been clearly demonstrated both experimentally and clinically. The impact of low flow and ischemia as a result of tissue edema progressively leads to capillary transit heterogeneity reflecting cerebral perfusion through microvascular shunts (MVS) has neither gas nor nutrient exchange with tissue . Low flow and cerebral ischemia and its impact on endothelial sheary rate detected by the glycocalyx wreaks havoc on endothelial function and degradation of the glycocalyx leading to: increased endothelial water permeability; increased adhesion of leucocytes to the endothelium and transendothelial transport to tissue; inflammatory activation; impaired antioxidant defenses; loss of coagulation control and impaired mechanotransduction. This cascade of events leads to exacerbation of brain edema and dysregulation of CBF and increased intracranial pressure (ICP), an important secondary injury process after severe TBI. The suggestion in light of these secondary injury processes after sTBI is that therapeutic interventions should be directed toward increasing CBF and preventing the development of brain edema early after sTBI as a targeted therapeutic intervention for sTBI. Our recent work with a high molecular weight drag reducing polymer increasing CBF by altering the physical dynamics of flow, not pharmacologically,
promises to be an effective therapeutic intervention in sTBI.
Keywords: Secondary Injury, Edema, Intracranial Pressure, Cerebral Blood Flow
ASTROGLIAL AND NEURONAL RESPONSE IN ATTENTION‐DEFICIT/HYPERACTIVITY DISORDER FOLLOWING SUBCONCUSSIVE HEAD IMPACTS
1Indiana University, Bloomington IN, United States, 2Alabama Life Research Institute, Tuscaloosa AL, United States
Keywords: Biomarker, Astrocyte, Concussion/mTBI, Attention
SODIUM‐HYDROGEN EXCHANGER (NHE1) AS A THERAPEUTIC TARGET FOR TRAUMATIC BRAIN INJURY
1Department of Neurology, University of Pittsburgh, Pittsburgh PA, United States, 2Pittsburgh Institute for Neurodegenerative Disorders, University of Pittsburgh, Pittsburgh PA, United States, 3Department of Neurological Surgery, University of Pittsburgh, Pittsburgh PA, United States, 4Veterans Affairs Pittsburgh Health Care System, Pittsburgh PA, United States
Dysregulated microglial (brain resident macrophage) function and pro‐inflammatory responses can cause white matter injury and/or inhibition of tissue repair. We explored a novel TBI therapeutic target aiming to reduce the microglial pro‐inflammatory responses while increasing the tissue repair phenotypes for remyelination. NHE1 protein mediates H+ efflux in exchange of Na+ influx, which regulate microglial intracellular pH and reactive oxygen species (ROS) production. We investigated whether blocking NHE1 activity can modulate microglial function and attenuate TBI. In our study, selective deletion of NHE1 in Cx3cr1‐CreERT2;Nhe1flox/flox (cKO) mice displayed improvements in motor‐sensory and cognitive function at 1‐30 days post‐TBI using the controlled cortical impact (CCI) murine model. Flow cytometry showed that cKO mice had increased CD206 and Ym‐1‐positive microglia by 3‐fold and 7‐fold, respectively, in the ipsilateral hemisphere, compared to wild‐type (WT) mice. These cKO mice concurrently showed enhanced white matter remyelination with increased corpus callosum thickness and enhanced oligodendrogenesis, along with less apoptosis at 3‐day post‐TBI. Post‐TBI administration of a NHE1 inhibitor HOE642 in WT mice showed similar microglial profiles to cKO mice at 3‐day post‐TBI and displayed improvement of neurological function with accelerated recovery in adhesive removal and foot fault tests. Taken together, these data showed that microglial NHE1 protein plays a role in inflammation and demyelination, demonstrating the potential of targeting microglial NHE1 protein as a novel therapeutic strategy for TBI.
Keywords: Neuroprotection, Behavioral Function, Secondary Injury, Concussion/mTBI, Therapeutics/Drug Discovery, Neuronal‐Glial Interactions, Inflammation/Immune Function, White Matter
NOCICEPTIN/ORPHANIN FQ PEPTIDE RECEPTOR ANTAGONIST RESCUES TRAUMATIC BRAIN INJURY‐INDUCED IMPAIRED CEREBRAL BLOOD FLOW
1Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City OK, United States, 2Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City OK, United States, 3Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City OK, United States, 4Stephenson Cancer Center, Oklahoma City OK, United States
Keywords: Concussion/mTBI, Therapeutics/Drug Discovery, Cerebral Blood Flow, Receptor Mediated/Signaling
PRE‐INTERVENTION BLOOD HYPERPHOSPHORYLATED TAU AND UBIQUITIN C‐TERMINAL HYDROLASE‐L1 CONCENTRATIONS ARE ASSOCIATED WITH MAGNITUDE OF SYMPTOM IMPROVEMENT FOLLOWING TARGETED INTERVENTION IN PATIENTS WITH CHRONIC TRAUMATIC BRAIN INJURY
1University Of Pittsburgh, Pittsburgh PA, United States, 2Uniformed Services University for Health Sciences, Bethesda MD, United States
Keywords: Rehabilitation, Biomarker, Blood Brain Barrier
UBIQUITIN C‐TERMINAL HYDROLASE‐L1 AND VON WILLEBRAND FACTOR AS POTENTIAL PREDICTIVE BLOOD BIOMARKERS FOR PATIENTS WITH PSYCHOLOGICAL ISSUES FROM CHRONIC TRAUMATIC BRAIN INJURY
1University Of Pittsburgh, Pittsburgh PA, United States, 2Uniformed Services University for Health Sciences, Bethesda MD, United States
Keywords: Rehabilitation, Biomarker, Sleep, Behavioral Function
HUMAN MSC‐DERIVED EXTRACELLULAR VESICLE TREATMENT AFTER TBI CAN DIMINISH CHRONIC NEUROINFLAMMATION BY BLOCKING NLRP3 INFLAMMASOME‐MEDIATED P38 MAPK SIGNALING CASCADE
Traumatic brain injury (TBI) results in acute neuroinflammation typified by nucleotide‐binding domain leucine‐rich repeat and pyrin domain‐containing receptor 3 (NLRP3) inflammasome activation, leading to a chronic inflammatory state. This study investigated the efficacy of a single intranasal (IN) dose of human mesenchymal stem cell‐derived extracellular vesicles (hMSC‐EVs) shortly after TBI for preventing chronic neuroinflammation. Small RNA sequencing confirmed that the hMSC‐EVs purified through anion‐exchange chromatography employed in the study were enriched with many miRNAs capable of modulating activated microglia and NLRP3 inflammasomes. Ninety minutes after a controlled cortical impact injury, adult mice received ∼25 billion EVs or vehicle. TBI mice receiving vehicle treatment exhibited robust NLRP3 inflammasome activation 48 hours post‐TBI, which persisted at three months post‐TBI. These were evidenced by higher concentrations of NLRP3 inflammasome components (NLRP3, apoptosis‐associated speck‐like protein containing a CARD [ASC], activated caspase‐1) and their products, interleukin‐1 beta (IL‐1β) and IL‐18. Moreover, proteomics suggested hyperactivated p38 mitogen‐activated protein kinase (MAPK) inflammatory signaling cascade, which could be confirmed from elevated levels of various proteins involved in MAPK activation and increased release of proinflammatory cytokines IL‐1β, IL‐6, IL‐8, and tumor necrosis factor‐alpha. Remarkably, hMSC‐EV treatment inhibited NLRP3 inflammasome activation in the acute phase of TBI, which was sustained in the chronic phase, resulting in no activation of p38 MAPK inflammatory signaling cascade, and decreased release of proinflammatory cytokines. Thus, a single IN dose of hMSC‐EVs is efficacious for blocking the activation p38 MAPK inflammatory signaling cascade after TBI by inhibiting NLRP3 inflammasomes, which results in reduced chronic neuroinflammation.
Keywords: Secondary Injury, Microglia, Therapeutics/Drug Discovery, Inflammation/Immune Function
THE ROLE OF PERIVASCULAR AQUAPORIN‐4 LOCALIZATION IN POST‐TRAUMATIC NEURODEGENERATION
1University Of Washington, Seattle WA, United States, 2VA Puget Sound Healthcare System, Seattle WA, United States
Traumatic brain injury (TBI) is a leading cause of death and disability worldwide and has been established as a risk factor for neurodegenerative diseases such as Alzheimer's disease (AD). Neurofibrillary tangles, aggregates of intracellular tau, are hallmarks of AD and are observed in the post‐TBI brain; however, the mechanisms that contribute to tau aggregation and accumulation are not well understood. One key mechanism that may contribute to this tau aggregation is decreased clearance by the glymphatic system, a perivascular pathway that clears solutes, including tau, from the brain. We have shown that following TBI there is loss of perivascular localization of the astrocytic water channel aquaporin‐4 (AQP4) and slowed solute clearance. We hypothesized that loss of perivascular AQP4 localization impairs interstitial tau clearance and promotes neurodegeneration. We examined whether loss of perivascular AQP4 localization in the Snta1‐/‐ mouse following TBI promotes tau pathology in a transgenic PS19 tauopathy mouse line. We found that glymphatic influx was impaired at 7 days following a closed‐head moderate impact TBI and impairment in learning was greatest in PS19 mice with loss of perivascular AQP4, as measured by Barnes maze 1‐month post‐TBI. These studies may provide a mechanistic basis for the vulnerability of the post‐traumatic brain to tau aggregation and neurodegeneration and suggest that targeting glymphatic dysfunction may be useful in the prevention and treatment of post‐TBI neurodegeneration.
Keywords: Astrocyte, Cerebrospinal Fluid, Neurodegeneration, Neuropathology
POST‐INJURY TIME‐COURSE OF MITOCHONDRIAL CALCIUM DYNAMICS, MEMBRANE INTEGRITY AND APOPTOSIS MARKERS FOLLOWING SEVERE PENETRATING TBI
1Walter Reed Army Institute of Research (WRAIR), Silver Spring MD, United States
Traumatic brain injury (TBI) remains a significant and urgent medical concern for the US military. From moderate to severe TBI, the most common mitochondria‐centered cellular excitotoxic responses involved are calcium (Ca2+), oxidative stress and energy homeostasis. Their imbalance subsequently prompt the downstream cellular processes such as apoptotic/necrotic cell death and ultimately alters behavioral outcomes after TBI. However, the time‐course analysis of mitochondrial excitotoxic responses are lacking in the pre‐clinical penetrating TBI (PTBI). Anesthetized adult male Sprague‐Dawley rats (280–350 g) were subjected to either 10% unilateral PTBI or Sham craniectomy, followed by excitotoxic responses evaluated at 30 min, 3h, 6h, 24h, 3d, 7d and 14d (n = 6‐10 animals/group X 7 time‐points). At each‐time point, animals were euthanized and mitochondria isolated from ipsilateral frontal cortex and striatum areas. Time‐course of PTBI group mitochondrial Ca2+ dynamics resulted in a “U‐shaped” loss in Ca2+ buffering capacity (12‐76%, vs. Sham) during the 2 weeks post‐injury period, with maximum loss noted at 24h post‐PTBI. Mitochondrial membrane integrity markers cytochrome c (Cyt C) and voltage‐dependent anion channel (VDAC) revealed significant loss (20‐50% vs. Sham) during the 2 weeks post‐injury period. Additionally, the glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) expression elevated significantly (∼2‐4 folds) in the PTBI group, which was reported as an indicator of apoptosis following injury. Following PTBI, brain region mitochondria showed loss of Ca2+ dynamics and early opening of permeability transition pore following PTBI. The current time‐course data demonstrated that an early therapeutic intervention is necessary to mitigate mitochondrial excitotoxic responses for achieving neuroprotection following PTBI.
Keywords: Excitotoxicity, Neuroprotection, Secondary Injury, Free Radicals
EXPLORING METHODS FOR CURATING DATA FROM THE GLASGOW OUTCOME SCALE‐EXTEND AND FUNCTIONAL STATUS EXAM INTERVIEWS
1Medical College Of Wisconsin, Milwaukee WI, United States
The Glasgow Outcome Scale‐Extended (GOSE) and Functional Status Examination (FSE) are widely used interviews of functional recovery from traumatic brain injury (TBI). Subjective patient report and variable interviewer practices can compromise the reliability and validity of GOSE and FSE scores. We examined the impact of two strategies to curate data from the GOSE and FSE according to their most current administration manuals. N = 307 interviews were conducted on 136 individuals using both the GOSE and FSE. Data were double entered to correct transcription errors, while an independent audio file review process was conducted on a subset of interviews (n = 106 GOSE; 105 FSE) to identify transcription errors, interpretation differences (due to ambiguous procedures or patient report), administrator deviations (deviations from the study interview protocol/manual), or other errors. A second rater rated audio recordings; a third rater resolved discrepancies between the original interviewer and second rater. Double entry resulted in changing the total score for 2.0% of GOSE and 1.3% of FSE interviews. Second audio‐file rating changed total score for 15.5% of GOSE and 9.9% of FSE interviews. Third raters almost always agreed with the second rater. Among the interview questions with code changes due to audio‐file rating, the most common reasons for changes were interpretation differences (41.7% GOSE, 50.7% FSE), transcription errors (29.4% GOSE, 15.7% FSE), and administrator deviations (12.9% GOSE, 20.1% FSE). The findings can inform the development of evidence‐based practice guidelines that balance the goals of accurate, reliable GOSE and FSE assessments and low personnel burden/cost in conducting outcome assessments.
Keywords: Cognition/Learning/Memory, Concussion/mTBI
EXERCISE AND PLASTICITY IN ADOLESCENCE: SEX AND RUNNING BEHAVIOR AFFECT DENDRITIC SPINE MORPHOLOGY IN RATS
Ms. Hannah Robert1, Molly Smith1, Miss Rebecka Serpa, Julie Bailard1, Ms. Payton Flores1, Dr. Tiffany Greco1, Dr. Lindsay Ferguson1, Dr. Michael Folkerts2, Dr. Mayumi Prins1
1University Of California Los Angeles, Los Angeles CA, United States, 2Pepperdine University, Malibu CA, United States
Adolescent athletes are particularly vulnerable to mild traumatic brain injury. This time period is characterized by active synaptic pruning. How exercise affects the developing brain pre‐injury at both acute and chronic timepoints remains unknown. Sex differences are particularly understudied. Given the influence of exercise and sex on cognitive functioning, and plasticity, these variables are vital in understanding neurotrauma. Objectives: This study characterized the effects of running behavior on neuroplasticity in adolescent (PD35) rats. Methods: 60 Sprague Dawley rats (31 males; 29 females) were given voluntary access to locked (sedentary) or functional (run) running wheels from 10:00am ‐ 6:00am for 10 days. One group was immediately euthanized (acute) while the other remained sedentary for an additional 10 days (chronic). The morphology of dendritic spines located in layer II/III of the medial prefrontal cortex were analyzed to examine plasticity. Z‐stack images of dendritic spines were processed via the RapidGolgi stain technique and measured using the RECONSTRUCT software. Results: Run and sedentary groups of both sexes did not differ in synaptic density. No differences in synaptic density were seen in run compared to sedentary groups at either time point in males and females. In the sedentary groups, females had more total spines and greater spine density than sedentary males at the acute time point only. Males, however, had more immature spine types than females. Conclusions: Results suggest that exercise may normalize sex differences in the adolescent pruning process.
Keywords: Concussion/mTBI, Synaptic Function, Exercise, Regeneration & Plasticity
TEMPORAL CHARACTERIZATION OF THE IMMUNE RESPONSE FOLLOWING REPEAT MILD TRAUMATIC BRAIN INJURY
1University of California, Irvine CA, United States
America is facing an epidemic with over 1.5 million individuals suffering from a traumatic brain injury (TBI) annually. While our understanding of TBI and its devastating effects is growing, less is known about a serious subtype of TBI called repeated mild TBI (rmTBI). Previous neurotrauma research suggests that immune cell activation is altered following injury. However, a comprehensive picture of immune cell infiltration and activation following rmTBI remains to be established. Therefore, this study will characterize the immune response at multiple timepoints following rmTBI using flow cytometry (FCM), immunohistochemistry, and stereological cell counting to establish a clear timeline for treatments to mitigate some of the damage seen in neurotrauma related conditions like chronic traumatic encephalopathy. Eight week old C57Bl6 male mice received five mild closed‐skull hits once every other day for 10 days using a controlled cortical injury device. The mice were sacrificed 1, 3, 7, 14, 28, or 60 days post injury (dpi) with an average of 6 mice per time point. Fresh brains were dissected and a two millimeter thick coronal section from ‐1 to ‐3 bregma was cut. Bilateral 4mm diameter biopsy punches were made at the midline at the dorsal‐most region to isolate the injury epicenter, which were then stained and processed by FCM. Macrophages/microglia, neutrophils, and T‐cells were fluorescently labeled and counted via FCM. A subsequent study was performed and quantification of the immune cell populations within the tissue using immunohistochemistry and stereology are ongoing.
Keywords: Secondary Injury, Microglia, Concussion/mTBI, Inflammation/Immune Function
INVESTIGATION OF EXERCISE INTOLERANCE IN CIVILIANS WITH MILD TRAUMATIC BRAIN INJURY (MTBI)
1Department of Neurosurgery, Medical College Of Wisconsin, Milwaukee WI, United States, 2UBMD Orthopardics and Sports Medicine, Buffalo NY, United States, 3SUNY Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo NY, United States, 4Departments of Medicine, Surgery and Physiology at the Medical College of Wisconsin, Milwaukee WI, United States, 5The Endocrine Research Laboratory at Aurora St. Luke's Medical Center, Milwaukee WI, United States, 6Advocate Aurora Research Institute, Milwaukee WI, United States, 7Department of Kinesiology, Indiana University, Bloomington IN, United States
The Buffalo Concussion Treadmill Test (BCTT) is a validated test of exercise tolerance frequently used to differentiate mTBI phenotypes (e.g., autonomic/physiological mTBI) and tailor exercise recommendations in youth athletes with mTBI. We examined the degree to which adult civilians with and without mTBI tolerate the BCTT (i.e., complete the 15‐minute test without meeting discontinue criteria). We also explored the relationship between baseline factors, mTBI‐related symptoms, and BCTT duration. N = 37 level 1 trauma center patients with mTBI and 24 healthy controls (HC) were assessed at 1‐week and 1‐month post‐injury with an interview, questionnaires (Rivermead Post‐Concussion Symptoms questionnaire [RPQ]; International Physical Activity Questionnaire), and the BCTT. Pre‐injury baseline variables considered were age, gender, body mass index [BMI], height, and activity level. mTBI participants completed the BCTT (i.e., made it to the 15‐minute limit) 14% and 16% of the time at 1 week and 1 month, respectively. Thirty percent of HCs completed the BCTT at both times. Greater BMI, shorter height, and female gender predicted shorter BCTT duration at one or more time points (1‐week/1‐month). Age and pre‐injury activity did not predict BCTT duration. Greater mTBI‐related symptom burden (higher RPQ score) was associated with shorter BCTT duration. Exercise intolerance was prevalent in civilians with and without mTBI through 1‐month post‐injury. That pre‐injury factors influenced tolerance to the BCTT indicates a need to further tailor the BCTT protocol to individual baseline characteristics (e.g., using lower starting speeds) to better discern individual exercise tolerance levels and determine the physiological effects of mTBI.
Keywords: Rehabilitation, Neuroprotection, Concussion/mTBI, Exercise
MEASURABLE PAIN PHENOTYPES AFTER SPINAL CORD INJURY
1McGovern Medical School At UTHealth Houston, Houston TX, United States, 2Baylor College of Medicine, Houston TX, United States, 3Emory University, Atlanta GA, United States, 4Washington University, St. Louis MO, United States
Keywords: Biomarker, Pain
C1Q‐RECEPTOR INTERACTIONS AS REGULATORS OF MICROGLIAL INFLAMMATION AFTER SCI
1University Of California, Irvine, Irvine CA, United States
Spinal cord injury (SCI) drives microglia, the immune cells of the central nervous system, into an inflammatory state within minutes following the injury. However, microglia can remain in this state for years following injury: inhibiting neural repair, driving secondary damage, and triggering chronic pain. Thus, understanding how microglial inflammation is initiated/maintained will identify novel targets to promote repair and regeneration after SCI. One molecular regulator of interest is C1q, the initiator molecule of the complement cascade that is highly abundant in the SCI microenvironment due to influx from the blood and increased production from immune cells. In this study, we utilize human induced pluripotent stem cell‐derived microglia (hiPS‐microglia) to test the hypothesis that C1q triggers microglial inflammation. Here, we show (1) exogenous C1q drives hiPS‐microglia to an inflammatory state, (2) hiPS‐microglia treated with lipopolysaccharide (LPS) shift to an inflammatory state and upregulate autocrine C1q production, and (3) blocking this autocrine C1q upregulation significantly attenuates LPS‐induced inflammation in hiPS‐microglia. To interrogate the mechanisms underlying this, we are investigating five novel C1q receptors that our lab recently identified (ADCY5, BAI‐1, CD44, cMET, and GPR62). RNA sequencing and proximity ligation assay (PLA) have validated receptor expression and C1q‐receptor candidate interactions at the microglial membrane, confirming a novel role for C1q as a ligand within hiPS‐microglia. Further characterization of C1q‐receptor interactions and their influence on microglial state will elucidate the mechanisms of microglial inflammation, allowing for the identification of therapeutic targets that will alleviate neuroinflammation and promote neural repair after SCI.
Keywords: Microglia, Stem Cells, Neuronal‐Glial Interactions, Inflammation/Immune Function
MULTIMODAL NEUROMONITORING AND NEUROCRITICAL CARE OF TRAUMATIC BRAIN INJURY IN SWINE
1Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, United States, 2Center for Neurotrauma, Neurodegeneration, & Restoration, CMC‐VA Medical Center, Philadelphia PA, United States, 3Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia PA, United States, 4Department of Anesthesiology and Critical Care Medicine, Perelman School of Medicine , University of Pennsylvania, The Children's Hospital of Philadelphia, Philadelphia PA, United States
Monitoring and responding to secondary injury processes—including altered intracranial pressure (ICP) and brain tissue oxygen (PbtO2)—following moderate‐to‐severe traumatic brain injury (TBI) is central to achieving a positive outcome. Preclinical study of neurocritical care requires an animal model that recapitulates injury mechanisms (e.g., rotational loading) and responses (e.g., coma) observed in humans. Herein we report replication of clinical multimodal neuromonitoring and neurocritical care in the swine rotational head acceleration model of TBI. Female swine (25–30kg) were induced via ketamine/midazolam, intubated, and maintained with isoflurane anesthesia. Femoral artery and internal jugular vein catheterizations allowed for continuous blood pressure monitoring and drug administration, respectively. Lumbar drain placement facilitated cerebrospinal fluid (CSF) sampling. Following rotational TBI, a quad‐lumen bolt was secured 1cm rostral to bregma for placement of a parenchymal ICP probe, PbtO2/temperature sensors, depth electrode, and microdialysis probe; afterwhich total intravenous anesthesia with propofol/fentanyl was initiated. Animals were monitored continuously up to 36h. EKG, SpO2, capnography, blood pressure, ICP, PbtO2/temperature, and EEG (depth+scalp) were time‐synchronized and continuously recorded with waveform resolution on a Moberg CNS‐200, and we collected arterial blood, CSF, microdialysate, and urine. Patterns and events mirrored those seen clinically. A large animal model replicating the mechanisms and manifestations of human TBI is essential to bridge the translational gap between rodent studies and clinical trials. The integration of neuromonitoring and critical care into such a model further increases translational relevance and allows for preclinical study of neurocritical care, while extending the study period for moderate‐to‐severe TBI with coma.
Keywords: Monitoring, Intracranial Pressure, Neurocritical Care, Consciousness
EXPLORATORY STUDY OF FACTORS ASSOCIATED WITH DEVELOPMENT OF POST‐TRAUMATIC EPILEPSY IN CHILDREN WITH ABUSIVE HEAD TRAUMA
1Department of Critical Care Medicine, Division of Pediatric Critical Care Medicine, Pittsburgh PA, United States, 2Department of Surgery, Division of Pediatric Surgery, University of Pittsburgh School of Medicine, Pittsburgh PA, United States, 3Department of Pediatrics, Division of Child Neurology, University of Pittsburgh School of Medicine, Pittsburgh PA, United States, 4Department of Pediatrics, Division of Child Advocacy, University of Pittsburgh School of Medicine, Pittsburgh PA, United States
Keywords: Pediatric, Epilepsy/Seizure, Concussion/mTBI, Neurocritical Care
BRCA1 DEFICIENT DNA REPAIR AND SEX‐SPECIFIC OUTCOMES FOLLOWING MILD TRAUMATIC BRAIN INJURY
1University of Toronto, Toronto, Canada, 2The Hospital for Sick Children, Toronto, Canada
Mild traumatic brain injury (mTBI) is a growing public health issue impacting millions of individuals annually. Resulting in psychiatric and cognitive symptoms, most individuals recover within a few weeks, while others experience symptoms for over a year. Moreover, different outcomes are often reported in women compared to men for reasons currently unknown. Previous research examining humans with history of mTBI reported upregulation in DNA damage and senescence‐associated genes, with downregulation in DNA repair genes. Among these DNA repair genes, breast cancer type I (BRCA1) was significantly downregulated. BRCA1 functions in maintaining genomic integrity, but also in maintaining neuron function in the brain. Thus, this research investigates BRCA1 in deficient DNA repair, its contribution to DNA‐damage induced senescence, and sex‐specific outcomes post‐mTBI. Mice heterozygous for BRCA1 (HET) were used in conjunction with a closed‐skull cortical impact model of mTBI, where pathological and behavioural outcomes were assessed 1‐ and 6‐weeks post‐injury. BRCA1 deficiency resulted in elevated levels of DNA damage and cellular senescence compared to wildtype and sham counterparts 1‐week post‐mTBI, with increased disinhibition associated with anxiety and worse cognition in males compared to females. At 6‐weeks post‐mTBI, injured mice exhibited a downregulation in DNA repair genes, with persistent neuroinflammation and behavioural deficits that was not exacerbated by BRCA1 deficiency. Evidence of a compensatory mechanism was also observed in BRCA1 deficient female mice post‐injury compared to wildtype counterparts that requires further investigation. These results support deficient DNA repair in promoting brain dysfunction through stress‐induced senescence, and its contribution to sex‐specific outcomes post‐mTBI.
Keywords: Gene Expression, Concussion/mTBI, Inflammation/Immune Function
IDENTIFYING NEUROPROTEOMIC BIOSIGNATURES FOR SPONTANEOUS POST‐TRAUMATIC EPILEPSY IN A CD1 MOUSE MODEL
1Unniversity Of Florida, Gainesville FL, United States, 2American University in Beirut, Beirut, Lebanon, 3Mario Negri Institute for Pharmacological Research, Milan , Italy
Traumatic brain injury (TBI) causes significant tissue damage, neuron and glia death, and axonal and metabolic abnormalities. TBI increases the risk of epilepsy. Post‐traumatic epilepsy (PTE) affects up to 50% of severe TBI patients. This study aimed to identify OMICS biomarkers of PTE in severe TBI at five months of CD1 male mice in the ipsilateral (IC) and contralateral cortices (CC) following PTE. We used a tandem mass tag (TMT‐11 PLEX) isobaric label proteomic workflow with liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) to identify differentially expressed proteins. Western blotting was carried out to validate proteins. Bioinformatics tools such as Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), were used to analyze the proteomic pathways. We found ∼25 (from ∼11,500 proteins) differentially expressed proteins (p < 0.01) from IC and CC brain tissues. Top upregulated proteins following PTE were β‐2‐globulin (IC, and CC), α‐globulin (CC), GFAP (IC), Myelin transcription factor 1 (IC), Transthyretin (CC), and Phospholipid‐transporting ATPase (CC) (p < 0.01). Top downregulated proteins following PTE include NADH dehydrogenase (IC), Dual Specificity Phosphatase 15 (IC), Inhibitory Synaptic Factor 2A (CC), Tubulin Beta 6 Class V (IC), MAGUK p55 subfamily member 2 (CC), and S100 calcium‐binding protein A9 (CC) (p < 0.01).Many critical biological processes and signaling pathways were involved in the brain damage caused by PTE in this study, such as inflammation, cell adhesion, phagocytosis, neuronal and synaptic damage, oxidative stress, and apoptosis. As Western blotting confirmed, these proteins and signaling pathways were linked to brain damage caused by PTE.
Keywords: Biomarker, Epilepsy/Seizure, Axonal Injury, Cell Death, Concussion/mTBI
NEUROBIOCHEMICAL AND PEPTIDOMIC APPROACH TO CHARACTERIZE POTENTIAL TAU PEPTIDOME BIOMARKERS FOLLOWING TRAUMATIC BRAIN INJURY ANIMAL MODEL
1Unniversity Of Florida, Gainesville FL, United States, 2Kuwait University , Abdullah Al Mubarak, Kuwait , 3American University of Beirut Medical Center, Beirut, Lebanon
Traumatic brain injury (TBI) is a complex condition with numerous medical complications. Tauopathies are diseases that cause abnormal hyperphosphorylation and aggregation of microtubule‐associated tau proteins. Caspases and calpain signaling cascades are activated within the cell after brain injury, resulting in tau truncation and fragmentation (MW400‐45,000 Da). Tau hyperphosphorylation and proteolysis cause neurodegenerative diseases like Alzheimer's, TBI, and chronic traumatic encephalopathy. Inhibiting a specific pathway involved in tau hyperphosphorylation, proteolysis, and oligomerization can reduce neurotoxicity and improve therapeutic outcomes. In this study, we investigated tau proteolytic fragments (<10 kDa) and pathological phosphorylation sites employing controlled cortical impact animal experimental model of TBI (CCI‐TBI). We used immunological (antibody‐based detection) and peptidomic‐based approaches. Following CCI‐TBI animal models, the immunoblotting experiment identified 55 kDa, 24 kDa, 15 kDa tau break‐down products, and 250 kDa high‐molecular‐weight bands. We also detected increased phosphorylation levels at multiple tau epitopes tested at days one, three, and seven. For peptidomic analysis, we used ultrafiltration (10 kDa molecular weight cut‐off) and nanoLC‐MS/MS to analyze the filtrates. Following CCI‐TBI, we identified novel tau low molecular weight peptides which were calpain‐mediated, including AEPRQEFEVMEDHAGTYG, SPRHLSNVSSTGSIDMVDSPQLATLADEVS, and STGSIDMVDSPQLA. The N‐terminal peptide AEPRQEFEVMEDHAGTYGLGDRKDQGGYT was found in multiple truncated isoforms following CCI‐TBI in our peptidomic analysis. We have also shown the power of sorting algorithms and open‐source software to visualize peptidomic data. The abundance of tau peptides from CCI‐TBI may contribute to neurodegeneration. Monitoring a subset of these targets generated by TBI may provide biomarker utility in enhancing clinical trials for new TBI drug development.
Keywords: Biomarker, Neurodegeneration, Axonal Injury, Concussion/mTBI, Computational/Modeling
IMPLEMENTATION OF NOVEL NEUROPROTEOMICS, BIOINFORMATIC, AND SYSTEM BIOLOGY APPROACHES IN ANIMAL MODEL OF OVERPRESSURE BLAST‐INDUCED TRAUMATIC BRAIN INJURY FOR BIOMARKER DISCOVERY AND THERAGNOSTIC POTENTIALS
1Unniversity Of Florida, Gainesville FL, United States, 2Kuwait University , Abdullah Al‐Mubarak, Kuwait, 3American University of Beirut, Beirut , Lebanon, 4Immunova, LLC, Gainesville, USA
A major cause of neurotrauma in modern military conflicts and terrorism is blast overpressure‐wave traumatic brain injury (OBI‐TBI). TBI diagnostic endpoints were lacking, which hampered TBI therapeutic development. This study aims to create a network map of blast brain injury biomarkers using a System Biology algorithm, using blast exposure of 24 hours (D1) and seven days (D7) in male Sprague‐Dawley rats. We used ipsilateral cortices of OBI and naive rat cortices. Polyacrylamide gel electrophoresis separated proteins (CAX‐PAGE). The trypsinized proteins were then identified and quantified using reversed‐phase LC‐MSMS. SDS‐PAGE and Western blotting were used to validate the top ten neuroproteomic proteins in OBI‐TBI cortex samples (n = 4). A rat protein ontology database was used to classify proteins into molecular functions, cellular components, and biological processes. It was made with PathwayStudio. After OBI‐TBI, 26 proteins were differentially expressed, ten downregulated and sixteen upregulated. Examples of downregulated proteins identified at OBI‐TBI‐D1 and D7 include phosphoglycerate kinase 1, Neurofascin, and synaptojanin 1. Other significant upregulated proteins at D1 and D7 include Mitochondrial Aconitate hydratase, Hexokinase‐1, Isoform 1A of Synapsin‐1, Ubiquitin carboxy‐terminal hydrolase isozyme L1, isoform 4 of Dynamin‐1 and, ‐3, and Mitochondrial 2‐oxoglutarate dehydrogenase E1 component. We used PANTHER to classify cellular and molecular functions . Our pathway analysis affects apoptosis and microtubule cytoskeleton assembly, among other things. These are all explained in the proposed model of controlled nonpenetrating blast in rats. Our findings revealed significant proteome changes that warrant further investigation and potential clinical trial biomarkers.
Keywords: Biomarker, Blast, Neurodegeneration, Axonal Injury, Diagnostics, Computational/Modeling, Informatics
WHITE MATTER DAMAGE EVALUATED BY MRI AND ACUTE PLASMA LEVEL OF NEUROFILAMENT LIGHT ANTICIPATE FUNCTIONAL IMPAIRMENT IN REPETITIVE MILD TRAUMATIC BRAIN INJURED MICE
1Laboratory of Acute Brain Injury and Therapeutic Strategies, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milan, Italy, 2Laboratory of Biology of Neurodegenerative Disorders, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milan, Italy, 3Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville FL, USA
Keywords: Biomarker, Axonal Injury, Concussion/mTBI
EFFICACY OF NEUROSURGEONS' DIRECT INTERVENTION TO SPORTS ORGANIZATIONS ON THE SOCIAL AWARENESS OF SPORTS HEAD INJURIES IN JAPAN
1Toho University Ohasi Medical Center, Tokyo, Japan
The search period is April 2016 to March 2021. The search objectives are 8 SOs. 4 SOs directly intervened by assuming the role of medical committee member. These organizations are direct‐intervention (DI) group.
Another 4 SOs indirectly intervened by education‐only, not assuming the role of medical committee member. These organizations are indirect‐intervention (II) group.
The examination items were as follows: 1) Medical committee (MC), 2) Concussion Guideline (CG), 3) Assessment tools (AT). Both groups received with follow‐up at 48 months. A comparison was made to identify whether the 4 year intervention produced changes in the 3 items observed for each group.
Keywords: Neurotoxicity, Concussion/mTBI
CHOLESTEROL ACCUMULATION IN LYSOSOMES IMPAIRS AUTOPHAGY IN MONONUCLEAR PHAGOCYTES AFTER TRAUMATIC BRAIN INJURY AND CONTRIBUTES TO NEUROINFLAMMATION
1University Of Maryland Baltimore, Baltimore MD, United States
Prolonged neuroinflammation, mediated by both resident microglia and infiltrating monocytes/macrophages, has been consistently observed in traumatic brain injury (TBI) and correlated to poor prognosis. Data from our laboratory demonstrate that inhibition of the catabolic pathway autophagy, in both activated microglia and infiltrating macrophages contributes to their proinflammatory phenotype in TBI lesion. However, the mechanisms responsible for the inhibition of autophagy in monocytes after TBI remain unknown. Our data, including LC‐SM/MS lipidomic analysis and immunofluorescent staining, demonstrate that inhibition of autophagy in infiltrating macrophages after TBI is associated with intracellular lipid accumulation and formation of lipid droplets. The phenotype resembles foam macrophages also observed in multiple sclerosis where it is thought to be caused by phagocytosis of myelin‐derived cholesterol, which is abundant in TBI lesion. Cholesterol accumulation has been shown to disrupt lysosomal function in various tissues. We hypothesized that excessive uptake of myelin debris and other complex cholesterol species such as oxidized LDL (oxLDL), which we also observed to be abundant in the TBI brain, leads to inhibition of autophagy after TBI. Consistently, we observed intracellular lipid accumulation and pronounced inhibition of autophagy in RAW macrophages exposed to several different cholesterol species including oxLDL. Cholesterol exposure also exacerbated LPS‐induced inflammatory responses. Our data also confirmed colocalization of lipid accumulation with lysosomal marker in monocytes in TBI brain sections. Our data support a mechanism where lipid and cholesterol accumulation in myeloid cells leads to lysosomal dysfunction and inhibition of autophagy, thus exacerbating TBI inflammatory responses.
Keywords: Microglia, Imaging, Inflammation/Immune Function
PLASMA NEUROFILAMENT LIGHT AND GLIAL FIBRILLARY ACIDIC PROTEIN LEVELS OVER 30 DAYS IN A PORCINE MODEL OF TRAUMATIC BRAIN INJURY
1University Of Pennsylvania, Philadelphia PA, United States
To establish the clinical relevance of porcine model of TBI using the plasma biomarkers with diffusion tensor imaging (DTI), we performed a randomized, blinded, preclinical trial using Yorkshire pigs. Twelve pigs were subjected to Sham injury (n = 5) or traumatic brain injury (n = 7) by controlled cortical impact. Blood samples were collected at 5‐day intervals until 30 days. Both groups also had diffusion tensor imaging (DTI) at 24 hours and at 30 days after injury. Plasma samples were isolated and single molecule array (Simoa) was performed for glial fibrillary acidic protein (GFAP) and neurofilament light (NFL) levels. Brain tissue samples were then stained for β‐APP. DTI showed FA decrease in the right corona radiata (ipsilateral to injury), contralateral corona radiata, and anterior corpus callosum at 1 day. At 30 days, ipsilateral corona radiata showed decreased FA. Pigs with TBI also had increase in GFAP and NFL at 1‐5 days after injury. Significant difference between Sham and TBI animals continued up to 20 days. Linear regression showed significant negative correlation between ipsilateral corona radiata FA and both NFL and GFAP levels at 1 day. Then, β‐APP immunohistochemistry was performed on a perilesional tissue as well as corona radiata bilaterally. Porcine model of TBI replicates the acute increase in plasma biomarkers seen in clinical TBI. Furthermore, long term white matter injury is confirmed in the areas such as the splenium and corona radiata. Future study stratifying severity of TBI and comparison with other subtypes of TBI such as diffuse axonal injury may be warranted.
Keywords: Biomarker, Imaging, Axonal Injury, Neuropathology
POPULATION LEVEL DATA PROVIDE EVIDENCE OF DISTURBED CENTRAL WHITE MATTER INTEGRITY ASSOCIATED WITH IMPAIRED COGNITIVE PERFORMANCE FOLLOWING TRAUMATIC BRAIN INJURY
1Institute of Health and Wellbeing, University Of Glasgow, Glasgow, United Kingdom, 2School of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom, 3Department of Neuropathology, Queen Elizabeth University Hospital, Glasgow, United Kingdom
There is recognition that traumatic brain injury (TBI) may lead to the development of mixed neuropathologies contributing to TBI related neurodegeneration (TReND), including persisting white matter degeneration. However, the relationship between white matter pathology and clinical outcome remains poorly defined. To address this, we tested for associations between TBI and specific magnetic resonance imaging (MRI) measures of white matter integrity and cognitive performance.
United Kingdom Biobank (UKB) is a general population cohort of around 0.5 million subjects enrolled between ages 40 and 70 years for prospective studies. From the UKB imaging sub‐study, participants were identified with prior history of TBI (n = 822), or as controls with no history of TBI (n = 47,098). MRI and cognitive measures were then compared, with outcomes adjusted for age, sex, social deprivation and cardiometabolic disease.
History of TBI associated with multiple MRI measures of disturbance in corpus callosum integrity, including decreased fractional anisotropy in the genu (fully adjusted standardized β ‐0.034, 95% CI 0.47 to ‐0.20), body (β ‐0.35, ‐0.48 to ‐0.21) and splenium (β ‐0.27, ‐0.41 to ‐0.12). Further, TBI associated with impaired information processing speed (Digit Symbol Substitution; β ‐0.14, ‐0.21 to ‐0.06) and executive function (Matrix Completion; β ‐0.09, ‐0.17 to ‐0.01), with imaging/cognitive phenotypes inter‐correlated (Pearson r range 0.05 to 0.21, P < 0.001).
Our data demonstrate history of TBI is associated with MRI evidence of white matter degeneration associated with reductions in measures of cognitive function, which may provide an imaging biomarker identifying individuals at greatest risk of TReND.
Keywords: Cognition/Learning/Memory, Aging, Imaging, Concussion/mTBI
THE IMPACT OF BDNF VAL66MET GENETIC POLYMORPHISM ON THE VULNERABILITY OF HUMAN MOTOR NEURONS TO IN VITRO STRETCH INJURY
Suning He1, Alyssa Weston1, Dr. John Finan2,
1Shirley Ryan AbilityLab/Northwestern University, Chicago IL, United States, 2Department of Mechanical and Industrial Engineering, Chicago IL, United States
Lower motor neuron (MN) loss after spinal cord injury (SCI) occurs several segments above and below the level of injury, but varies a lot between patients. Genetic variation may contribute to this variation, but has proved difficult to isolate. To begin to define how genetic variation may affect SCI outcomes, we employed a stem cell‐based assay to isolate the effects of the Val66Met single nucleotide polymorphism in the brain‐derived neurotrophic factor (BDNF) gene. BDNF Val66Met carriers have impaired activity‐dependent release of BDNF protein and this is implicated in altered clinical neurotrauma outcomes. It is also highly prevalent, carried by about 1/3rd of the US population. To test the hypothesis that carriers of the Met allele are more susceptible to motor neuron degeneration after injury, we use an in vitro stretch injury model designed for human induced pluripotent stem cell (iPSC)‐derived motor neurons. We apply different strain levels to isogenic iPSC‐motor neurons (gene edited to differ by only the presence or absence of the Met allele), then measured the cell viability and neurite length after the injury. The results show that motor neurons with the Met allele are more susceptible to neurodegeneration. This genotype difference could be ameliorated by adding recombinant BDNF to injured motor neurons before injury, which implies a BDNF‐TrkB signaling mechanism. Transcriptomic analysis of isogenic iPSC‐motor neurons by RNA sequencing reveals differential expression of 1491 genes (613 upregulated, 878 downregulated) with gene ontology enrichment analysis identifying both TrkB and other pathways altered by this genetic variation.
Keywords: Stem Cells, Genetic Factors, Cell Death, Regeneration & Plasticity
COMORBIDITY PHENOTYPE TRAJECTORIES IN VETERANS BEFORE AND AFTER EMERGENCE OF EPILEPSY: THE ROLE OF TBI
1VA Salt Lake City, Salt Lake City UT, United States, 2University of Utah, Salt Lake City UT, United States, 3Wounded Warrior Foundation, Jacksonville FL, United States, 4Hunter Holmes McGuire VA Medical Center, Richmond VA, United States, 5Virginia Commonwealth University, Richmond VA, United States, 6VA Connecticut Healthcare System , West Haven CT, United States, 7Yale University, West Haven CT, United States, 8University of Texas Health Science Center San Antonio, San Antonio TX, United States
Comorbidities common in epilepsy are burdensome to patients and may also be associated with mortality. Little is known aboutphenotypic patterns of comorbidity before and after emergence of epilepsy, or their associations with mortality/cause of death.
Bipolar/Substance Use Disorder (SUD)
Chronic Disease (CD): hypertension, stroke, cardiac disease
Post‐traumatic Stress Disorder (PTSD): PTSD, TBI, headache
Polytrauma: TBI, PTSD, pain. headache, lung disease
Mortality was significantly higher for CD and Bipolar/SUD groups (p < .01). Death by Accident/suicide was significantly higher in PTSD, Bipolar/SUD, and Deterioration groups. Cancer death was significantly higher in the Healthy group. Stroke death was significantly higher in CD (p < .01).
Keywords: Aging, Epilepsy/Seizure, Concussion/mTBI, Computational/Modeling
PRESSURE CHANGES IDENTIFIED BY SMARTPILL AFTER SPINAL CORD INJURY IN A PORCINE SCI MODEL
Mr. Chase Knibbe1,2,
1University of Louisville School of Medicine, Louisville KY, United States, 2Department of Neurological Surgery and KY Spinal Cord Injury Research Center, Louisville KY, United States, 3Comparative Medicine Research Unit, University of Louisville, Louisville KY, United States, 4Division of Gastroenterology, Hepatology, and Nutrition, Department of Internal Medicine, University of Louisville, Louisville KY, United States, 5Medtronic Inc., Minneapolis MN, United States, 6Research Service, Robley Rex Veterans Affairs Medical Center, Louisville KY, United States
Autonomic disruptions after SCI (spinal cord injury) can lead to severe gastrointestinal (GI) dysfunction. To assess these autonomic disruptions, we employed the Smartpill™ which actively transmits pH, temperature, and pressure. The Smartpill™ was administrated to three pigs in the fed state before T10/T11 SCI from a 10cm drop height and at 2‐ and 6‐weeks post‐injury. MotiliGI® and GIMS® software were then used to generate transit times, contraction frequency (ConFreq), and maximum pressure (SumAmp). Tributyrin, a triglyceride that treats gut dysbiosis, was also administered to pigs 1 and 2 post‐injury BID for 8 weeks. We found an initial decrease in ConFreq and SumAmp in the stomach at 2‐weeks post‐injury and a slight increase at 6‐weeks post‐injury. Small intestine pressures appear unaffected with decreases only noted in the duodenum. Decreases in ConFreq were observed for all colonic quartiles at both post‐injury time points, with a corresponding increase in SumAmp, indicating less frequent but more forceful contractions. For example, animal 1's pre‐injury ConFreq and SumAmp for each quartile were 1.59, 1.76, 1.84, 1.44, and 950.81, 34.86, 1721.61, 1052.29, respectively. At 6 weeks post‐SCI, the concentration frequencies decreased to 0.08, 0.04, 0.16, 0.14 while the maximum pressures increased to 1656.46, 660.02, 2522.4, 2912.1. This trend was also seen with the other 2 pigs in the study. We also observed delays in Gastric Exit Times (GETs) and Colon Transit Times (CTTs) at both 2‐ and 6‐weeks post‐injury. These observations are consistent with the limited available data, both in pre‐clinical and in human studies.
Keywords: Secondary Injury, Endocrine, Nutrition, Metabolism/Energetics
SEIZURE SUSCEPTIBILITY AND SLEEP STRUCTURE AS BIOMARKERS FOR EPILEPTOGENESIS AFTER EXPERIMENTAL TBI
1UEF, Kuopio, Finland
Keywords: Sleep, Epilepsy/Seizure, Electrophysiology
CHRONIC CORTICAL INFLAMMATION, COGNITIVE IMPAIRMENT AND IMMUNE REACTIVITY ASSOCIATED WITH DIFFUSE BRAIN INJURY ARE AMELIORATED BY FORCED TURNOVER OF MICROGLIA
1The Ohio State University, Columbus OH, United States
Traumatic brain injury (TBI) is associated with an increased risk of cognitive, psychiatric, and neurodegenerative complications that may develop and persist years after injury. Increased microglial reactivity following TBI may underlie chronic neuroinflammation, neuropathology, and exaggerated responses to immune challenges. Therefore, the goal of this study was to force turnover of trauma‐associated microglia that develop after diffuse TBI and determine if this alleviated chronic inflammation, improved functional recovery and attenuated reduced immune reactivity to lipopolysaccharide (LPS) challenge. Mice received a midline fluid percussion injury and 7 days later were subjected to a forced microglia turnover paradigm using CSF1R antagonism (PLX5622). At 30 days post injury (dpi), cortical gene expression, dendritic complexity, myelin content, neuronal connectivity, cognition, and immune reactivity were assessed. Myriad neuropathology‐related genes were increased 30 dpi in the cortex, and 90% of these gene changes were reversed by microglial turnover. Reduced neuronal connectivity was evident 30 dpi and these deficits were attenuated by microglial turnover. TBI‐associated dendritic remodeling and myelin alterations, however, remained 30 dpi independent of microglial turnover. In assessments of functional recovery, increased depressive‐like behavior, and cognitive impairment 30 dpi were ameliorated by microglia turnover. To investigate microglial priming and reactivity 30 dpi, mice were injected i.p. with LPS. This immune challenge caused prolonged lethargy, sickness behavior, and microglial reactivity in the TBI mice. These extended complications with LPS in TBI mice were prevented by microglia turnover. Collectively, microglial turnover 7 dpi alleviated behavioral and cognitive impairments associated with microglial priming and immune reactivity 30 dpi.
Keywords: Microglia, Cognition/Learning/Memory, Neuronal‐Glial Interactions, Inflammation/Immune Function
NEUROREHABILITATION, EIGHTEEN MONTHS POST DIFFUSE AXONAL INJURY, IS IT EVER TOO LATE?
1Plasticity Centers, Marietta GA, United States
Keywords: Rehabilitation, Behavioral Function, Cognition/Learning/Memory, Axonal Injury
DELAYED INTRANASAL LEUKEMIA INHIBITORY FACTOR PREVENTS TERTIARY NEURODEGENERATION AFTER A MILD CONCUSSIVE HEAD INJURY
1New Jersey Medical School, Newark NJ, United States, 2Yale University, New Haven CT, USA, 3Robert Wood Johnson Medical School, New Brunswick NJ, USA
We recently showed that administering LIF intranasally (IN) acutely after a mTBI prevents axonal injury and reduces gliosis. Therefore, we hypothesized that IN‐LIF Rx would prevent neurodegeneration when adminstered during the chronic period of recovery from a mTBI. To test this hypothesis, 8‐10 week old male CD1 mice were subjected to a closed head injury using a flat 3mm metal impactor positioned just in front of bregma (velocity of 4.0m/s; depth of 1.3mm; dwell time of 100ms). LIF was administered 2X daily, 5 days/week during the 7th and 8th week following mTBI. We assessed microstructural integrity in fixed brains using a 9.4T Bruker BioSpin MRI, metabolite levels by LC‐MS/MS and sensorimotor function. At 9 weeks after the mTBI, IN‐vehicle Rx mice showed significantly increased mean difussivity (MD) and decreased fractional anisotropy (FA) in the corpus callosum (CC) when compared to shams. IN‐LIF Rx significantly decreased MD in the motor cortex with a trend towards decreased MD in the CC vs. IN‐vehicle group. LC‐MS/MS analyses of the CC showed a significant increase in NAD+ levels and overall increase in amino acids in IN‐LIF Rx mice. Importantly, IN‐LIF Rx mice performed better than the IN‐vehicle group on a test of fine motor function. However, no significant differences in Catwalk gait analysis was observed. Our studies recommend delayed IN‐LIF administration as a prospective therapeutic for improving neurological function in young adults battling the chronic phase of mTBI. Supported by R21 NS125201 awarded to SK and SWL.
Keywords: Neuroprotection, Secondary Injury, Astrocyte, Microglia, Imaging, Axonal Injury, White Matter
TYPE I INTERFERONS CONTRIBUTE TO CHRONIC MICROGLIAL‐MEDIATED INFLAMMATION AND NEUROLOGICAL DECLINE FOLLOWING EXPERIMENTAL TRAUMATIC BRAIN INJURY IN MICE
1University Of Maryland, Baltimore MD, United States, 2Trinity College Dublin, Dublin, Ireland
Keywords: Secondary Injury, Microglia, Inflammation/Immune Function, Receptor Mediated/Signaling
A NOVEL ROLE FOR MATRIX METALLOPROTEINASES IN ABNORMAL REMODELING OF THE BLADDER WALL AFTER SPINAL CORD INJURY AND LONG‐TERM LOSS OF BLADDER COMPLIANCE
1University of Texas at Austin Dell Medical School, Department of Neurology, Austin TX, USA, 2University of California at San Francisco, Department of Laboratory Medicine, San Francisco CA,USA, 3Texas A&M University College of Veterinary Medicine and Biomedical Sciences, Department of Small Animal Clinical Sciences, College Station TX, USA, 4University of California at San Francisco, Department of Neurological Surgery, San Francisco CA, USA, 5University of Texas at Austin, Department of Psychology, Austin TX, USA
Loss of bladder compliance after spinal cord injury (SCI) has been poorly addressed in the research community despite its impact on quality of life, ranging from the inconvenience of frequent bladder evacuations to increased risk of kidney infections and mortality. SCI results in abnormal stretch of the bladder wall which may signal hyperplasia and/or hypertrophy in the detrusor muscle and increased extracellular matrix production, which collectively contribute to loss of compliance. Recent studies in spinal cord injured dogs, treated systemically with a general matrix metalloproteinase (MMP) inhibitor in the acute phase, resulted in long‐term improvement in bladder compliance. This suggests that MMPs, well known for tissue remodeling, may be directly acting on the bladder wall and that this gives rise to a loss of bladder compliance. Consistent with this hypothesis, we find that spinal cord injured mice, treated systemically with a general MMP inhibitor within the acute phase, show long‐term improvement in voiding efficiency coincident with a significant reduction in detrusor area, compared to vehicle controls. Gelatin and in situ zymography confirm early upregulation of MMP‐2 and MMP‐9 and rtPCR shows dynamic regulation of multiple MMP family members in the bladder wall within the first week post‐SCI. Systemic MMP blockade reduces early smooth muscle proliferation, possibly via an ERK‐dependent signaling cascade. These collective findings suggest a novel role for MMPs after SCI through their direct action on the bladder wall, functioning as early determinants of long‐term urological recovery. Funded by the Craig H. Neilsen Foundation.
Keywords: Secondary Injury, Therapeutics/Drug Discovery
ASSOCIATION BETWEEN CHRONIC CANNABIS USE AND NEUROLOGIC RESPONSE TO ACUTE SUBCONCUSSIVE HEAD IMPACTS
1Indiana University, Bloomington IN, United States, 2Alabama Life Research Institute, Tuscaloosa AL, United States
Keywords: Biomarker, Neuroprotection, Astrocyte, Concussion/mTBI
TRANSLATIONAL OUTCOMES PROJECT IN NEUROTRAUMA (TOP‐NT): PHENOTYPES OF ACUTE CORTICAL TRAUMA AND THEIR SYNDROMIC REPRESENTATION BY NONINVASIVE NEUROIMAGING AND BIOMARKER SIGNATURES
1University Of California, San Francisco, San Francisco CA, United States, 2University of Miami, Miami FL, United States, 3University of California, Los Angeles, Los Angeles CA, United States, 4EnCor Biotechnologies, Gainesville GA, United States, 5BRAINBox Solutions, Inc., Richmond VA, United States
Translational studies have struggled to fully capture clinical heterogeneity in the laboratory. Experimental TBI research is poorly integrated as most studies focus on single parameters (e.g., cell type, molecule, tool). To better capture injury phenotypes, Translational Outcomes Project in Neurotrauma (TOP‐NT) employs a multimodal approach across three domains (histopathology, neuroimaging, fluid biomarkers) assessing controlled cortical impact in rats. To enable phenotypic indexing, we conducted principal component analysis (PCA), a multidimensional technique for detecting patterns across variables as principal components (PC) each covering a proportion of the dataset's variance (%). Histopathology PC1 (49%) was dominated by injury day blood extravasation in the contusion core that was more pronounced in females. One‐day postinjury, cytological trauma was accompanied by non‐cellular proteinopathies of astroglial and neuronal markers, aldolase C (ALDOC) and neurofilament light (NF‐L; 25%PC2). This was preceded by pericontusional neuronal fiber loss (11%PC3). MRI PC1 (46%) captured early decreased mean diffusivity (MD) including axial (AD) and radial diffusivity (RD) likely capturing cell swelling and membrane failure. Subsequent vasogenic edema was reflected by increased MD, AD and RD (25%PC2). Remarkably, an independent cohort validated these MRI components. The biofluid PCA revealed different profiles for two CSF and serum astroglial biomarkers, glial fibrillary acidic protein (GFAP) and ALDOC. Hyperacute ALDOC serum levels loaded independently (14%PC3), suggesting different release kinetics and expression. In conclusion, our intra‐domain PCAs typified sex‐dependent and temporal injury events and their proportional importance. This provides confidence that multidimensional approaches can identify phenotypes, which may facilitate diagnostic monitoring and targeted treatment strategies.
Keywords: Biomarker, Astrocyte, Imaging, Informatics
HARMONIZING DATA ACROSS OPERATION BRAIN TRAUMA THERAPY IDENTIFIES DISTINCT, BIOMARKER‐PROJECTED MULTIMODAL PROFILES OF THREE TYPES OF EXPERIMENTAL TRAUMATIC BRAIN INJURY
1University of Miami, Miami FL, United States, 2University of Messina, Messina, Italy, 3University of Pittsburgh, Pittsburgh PA, United States, 4Walter Reed Army Institute of Research, Silver Spring MD, United States, 5University of Florida, Gainesville GA, United States, 6Banyan Biomarkers Research, Alachua FL, United States, 7University of California, San Francisco, San Francisco CA, United States
The multi‐center Operation Brain Trauma Therapy (OBTT) consortium generated a large dataset comparing outcomes across animal models. We explored the potential utility of harmonizing data from 531 male rats subjected to one of three TBI models (fluid percussion injury [FPI], controlled cortical impact [CCI], and penetrating ballistic‐like brain injury [PBBI]) and the predictive value of blood‐based biomarkers. One‐month of testing including blood biomarkers (glial fibrillary acidic protein [GFAP] and Ubiquitin carboxy‐terminal hydrolase‐L1 [UCH‐L1]), behavior, and histology followed injury. Applying common data elements, variables from each center were harmonized. The stats and syndRomics R packages were used for analysis and interpretation. We observed associations between biomarkers, behavior, and histology explaining 96.2% of the variance. PC loadings found these associations to be injury‐type dependent. The best behavior and least severe histological measures exhibited an exaggerated GFAP 4h response dissipating by 24h. UCH‐L1 impact was near‐zero. Rats in the middle of behavioral and histological severity showed increased UCH‐L1 (both time points) and increased GFAP at 24h. The most impaired behavior and severe histology were associated with both UCH‐L1 time points but never GFAP. Plotting each rat across PC1 and PC2 revealed these profiles corresponded to FPI, CCI, and PBBI, respectively. We report successful harmonization of data across OBTT, demonstrating that TBI models yield identifiably distinct injuries. This work also emphasizes the importance of data sharing and interoperability approaches to identify phenotype‐biomarker associations and develop innovative data‐driven strategies for precision medicine in TBI.
Keywords: Biomarker, Cognition/Learning/Memory, Computational/Modeling, Neuropathology
BLAST‐RELATED OCULOMOTOR FUNCTIONAL DEFICITS: ACUTE AND CHRONIC EXPOSURE EFFECTS
1Walter Reed Army Institute of Research, Silver Spring MD, United States, 2Oak Ridge Institute for Science and Education, Oak Ridge TN, United States
Exposure to explosive blast is a risk to neurologic function and behavioral performance. Our research team has sought an objective, automated measure of eye tracking to reveal subtle functional deficits among military cohorts exposed to blast in training but who are otherwise regarded as clinically normal and healthy. Here, we report a pilot assessment with explosive entry instructors (“breachers”) within 2 hours of exposure (acute), building upon our previous reporting of subacute effects across a 3‐year timeframe (chronic). We administered SyncThink's EYE‐SYNC eye tracking measure to 11 volunteer breaching instructors at the beginning of an intensive training day, before exposures to multiple explosive detonations. In EYE‐SYNC scoring, greater magnitude scores reflect greater variance in eye tracking during the visual smooth pursuit task and, thus, worse performance. Scores at the end of the day, following exposures, were elevated relative to each individual's baseline except for the one volunteer who was exposed at lower magnitudes due to greater distance from detonations (t = 3.42, p = .03). In subsequent assessment, 8 hours from most recent exposure and after overnight sleep, EYE‐SYNC scores had returned towards baseline levels (t = ‐3.01, p = .04). This preliminary result of an eye tracking deficit following acute exposure to blast is consistent with our previous reporting in which we observed increasing error scores across breaching sessions and over time (several months; r = .32, p = .02), suggesting deficit accrual commensurate with chronic exposure. Our eye tracking assessment studies are being evaluated as a candidate component of longitudinal brain health monitoring for service members repeatedly exposed to blast.
Keywords: Blast
INITIAL COMPARISON OF THREE EYE‐TRACKING DEVICES FOR DETECTION OF OCULOMOTOR CHANGES FOLLOWING TRAUMATIC BRAIN INJURY
1Walter Reed Army Institute of Research, Silver Spring MD, United States, 2National Intrepid Center of Excellence, Bethesda MD, United States, 3Bloomsburg University, Bloomsburg PA, United States, 4Oak Ridge Institute for Science and Education, Oak Ridge TN, United States
Oculomotor testing has been identified as a possible indicator of traumatic brain injury (TBI) due to its sensitivity to impaired neural pathways. Three commercially available eye‐tracking devices (SyncThink EYE‐SYNC, Oculogica EyeBOX, NeuroKinetics IPAS) were selected by the US Army Medical Research and Development Command Non‐Invasive NeuroAssessment Devices (NINAD) Integrated Product Team as meeting criteria towards being operationally effective in detection of TBI in service members. This study seeks to provide analytical comparison of these devices to inform of viability of use with servicemembers. We present here initial findings obtained from twelve participants with chronic symptoms of mild TBI recruited from the patient population at the National Intrepid Center of Excellence in comparison with healthy controls with no reported TBI history. Each participant completed a TBI assessment protocol with all three devices that was counterbalanced across participants. Data from each device was analyzed to determine optimal metrics for classification of subjects as TBI or control, which was used to generate Area Under the Curves (AUC) to enable comparison of device sensitivity/specificity to TBI. AUCs obtained from this initial analysis ranged from 0.649 to 0.820, indicating that all three devices demonstrated varying capacity to distinguish TBI cases from controls. While the AUCs presented here suggest differential performance amongst the three devices, these findings were obtained from a small sample of long‐term post‐injury subjects. Ongoing data collection and analysis will provide more accurate determination of device capabilities with larger sample size and inclusion of acute TBI data.
Keywords: Concussion/mTBI
UNLIKE GENERAL NEUROSURGEONS, NEUROTRAUMA SURGICAL TRIALISTS ARE AS DIVERSE AS THE PARTICIPANTS THEY ENROLL: A SYSTEMATIC SAMPLING REVIEW
1University of Ottawa, Faculty of Medicine, Ottawa, Canada, 2Ashbury College, Ottawa, Canada, 3Spine Program, University of Ottawa; Division of Orthopedic Surgery, The Ottawa Hospital, Ottawa, Canada, 4Ottawa Hospital Research Institute; Division of Neurosurgery, The Ottawa Hospital; University of Ottawa, Ottawa, Canada
Keywords: Concussion/mTBI, Hemorrhage
ASSESSMENT OF CHRONIC NEURODEGENERATION FOLLOWING A TRAUMATIC BRAIN INJURY
1School of Biological and Health Systems Engineering, Arizona State University, Tempe AZ, United States, 2Department of Neurobiology, Barrow Neurological Institute, Phoenix AZ, United States
Directly following the primary impact from a traumatic brain injury (TBI), secondary injury sequalae ensues consisting of consecutive injury induced pathological processes. The primary injury event is considered irreversible, however, the secondary sequalae may be targeted to improve the patient's outcome in the minutes and years after suffering a TBI. In this histochemical based study, we have identified evidence of significant neurodegenerative effects in both the cortex distal from the initial injury region and the cervical spinal cord following a TBI. In both the cortex and cervical spinal cord of injured mice, we have revealed a significant number of neuronal cells that display a nuclear mislocalization of the TAR DNA Binding Protein 43 (TDP‐43) when compared to age‐matched naïve control animals. Cells displaying this nuclear mislocalization also showed cytosolic accumulations of TDP‐43 that appeared heavily ubiquitinated. These cellular abnormalities were detected post injury at up to 180 days. TDP‐43 nuclear mislocalization, cytosolic aggregation with ubiquitination, and hyperphosphorylation, are known as hallmarks of amyotrophic lateral sclerosis (ALS) and are also found in ∼50% of frontotemporal lobar degeneration, up to 70% of Alzheimer's disease patients, and is a prominent feature of Parkinson's and Huntington diseases. Our results indicate that secondary injury sequelae following a TBI leads to a chronic neurodegenerative state and supports a link between TBI and the development of neurodegenerative disease.
Keywords: Secondary Injury, Aging, Neurodegeneration, Neurotoxicity, Neuropathology
TRANSLATING INJURY BIOMECHANICS RESEARCH INTO CLINICAL TOOLS FOR ENHANCING TBI EVALUATION
1University Of Virginia, Charlottesville VA, United States
Combining brain biomechanics and symptomology associated with an injury can be challenging for both engineers and clinicians. It can be difficult for a clinician to contextualize the forces and risks of a traumatic brain injury (TBI) in complex scenarios, and, conversely, difficult for an engineer to understand symptoms stemming from TBIs. Therefore, the goal of this research was to bridge these disciplines and develop a web‐based toolkit for clinicians to assess the risk of TBI in specific automotive crashes and to provide context of the severity of head impacts. First, the toolkit allows clinicians to input the factors related to the patient (e.g., age, sex, height, weight) and automotive crash (e.g., speed, crash direction, model year) to output the risk and severity of TBI based on epidemiology from field data. To help interpret impact severity associated with automotive crashes, a database of head kinematics (n = 210) was generated using computational crash models across a variety of crash conditions and occupant characteristics. A regression tree model was trained using the crash parameters to predict brain injury metrics, DAMAGE and HIC (R2 = 0.8 and R2 = 0.84, respectively), and was validated on a unique set of crash conditions (n = 50). These brain injury metrics were then linked to brain injury metrics from experimentally collected head kinematics (n = 103) (e.g., helmet impacts or falling) to provide the clinician a relatable example. This toolkit offers the clinician a better understanding of the biomechanical impact resulting from an injury and enables research relating patient outcomes to the severity of the impact.
Keywords: Concussion/mTBI, Diagnostics, Computational/Modeling, Biomechanics
USE OF RESPONSIVE NEUROSTIMULATION FOR TREATMENT OF REFRACTORY EPILEPSY AFTER TRAUMATIC BRAIN INJURY: A CASE SERIES
Dr. Jorge Roa, Dr. Fedor Panov, Dr. Saadi Ghatan,
1Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York NY, USA
Keywords: Epilepsy/Seizure, Neural Engineering
NEUROVASCULAR COUPLING IN ACUTELY CONCUSSED PEDIATRIC PATIENTS
1Center for Injury Research and Prevention, The Children's Hospital of Philadelphia, Philadelphia PA, United States, 2Perelman School of Medicine, University of Pennsylvania, Philadelphia PA, United States, 3Sports Medicine Performance Center, The Children's Hospital of Philadelphia, Philadelphia PA, United States, 4Division of Emergency Medicine, The Children's Hospital of Philadelphia, Philadelphia PA, United States
Neurovascular coupling (NVC) describes cerebrovascular response to neural activation and is impaired following concussion in adults. It is unclear if pediatric patients experience impaired NVC acutely following concussion. The purpose of this study was to investigate NVC in acutely concussed pediatric patients relative to controls. This prospective cohort study recruited patients presenting to a sports medicine clinic within 28 days of a concussion (cases) or a musculoskeletal injury (controls). Transcranial doppler was used to measure changes in patients' posterior cerebral artery velocity (PCAv) in response to a reading and visual search task. PCAv response was time‐aligned to stimulus onset to generate a single curve representing NVC response for each participant for each task. Separate linear mixed effects models were used to evaluate group differences in NVC response profiles for both visual tasks. Twenty‐one cases (female = 9(42.9%); age = 14.4 ± 1.9 years) and 10 controls (female = 5(50%); age = 13.7 ± 1.5 years) were included. On average, cases presented with higher relative NVC response curves during the reading task (1.1% increase) and the visual search task (4.4% increase) relative to controls. Our data indicate that concussed patients present with elevated NVC response to visual tasks, particularly the more complex visual search task. This may suggest that concussed patients require increase neural resource allocation to complete a visual task relative to controls. The study provides insight into the neurophysiological consequences of concussion in pediatric patients.
Research supported by National Institute of Neurologic Disorders and Stroke of the National Institutes of Health (R01NS097549 and T32NS043126) and the Pennsylvania Department of Health.
Keywords: Pediatric, Concussion/mTBI, Cerebral Blood Flow
BLOOD‐BRAIN BARRIER DYSFUNCTION PREDICTS MICROGLIAL ACTIVATION FOLLOWING TBI IN JUVENILE RATS
1University Of Arizona, College of Medicine, Phoenix AZ, United States, 2University of Colorado Boulder ‐ Department of Integrative Physiology, Boulder CO, United States, 3Phoenix Veteran Affairs Health Care System, Phoenix AZ, United States
Traumatic brain injury (TBI) disrupts the blood‐brain barrier (BBB), a critical regulator of brain homeostasis, which may exacerbate neuroinflammation post‐injury. Children are more susceptible to BBB breakdown after infection; however, few translational studies have examined BBB dysfunction and subsequent neuroinflammation following TBI in juveniles. We hypothesized that BBB dysfunction positively predicts microglial activation and that vulnerability to BBB dysfunction and associated neuroinflammation are dependent on age‐at‐injury. Post‐natal‐day (PND)17 and PND35 rats (n = 56) received midline fluid percussion injury or sham surgery. We investigated BBB dysfunction and the cortical microglial response relative to age‐at‐injury and days post‐injury (DPI; 1, 7, 25). Immunoglobulin‐G (IgG) stain was quantified as a marker of BBB dysfunction. We measured the morphologies of Iba1‐labeled microglia using cell body area, branch length, branch endpoints, and cell abundance. Data were analyzed using Bayesian multi‐level models. TBI increased levels of IgG compared to shams, regardless of age‐at‐injury or DPI. In both PND17 and PND35 rats, TBI activated microglia (more cells, shorter branches, fewer endpoints, larger area) compared to uninjured shams, specifically at 1DPI and 25DPI. PND17 rats had more activated microglia compared to PND35 rats, independent of TBI. Importantly, we found support in both ages that IgG quantification predicted microglia activation after TBI: Microglia cell abundance increased with increasing IgG, whereas both branch length and number of endpoints decreased with increasing IgG, which collectively indicate microglia activation. Our data indicate that stabilization of the BBB after pediatric TBI is an important therapeutic strategy to limit neuroinflammation and promote recovery.
Funding‐NINDS‐R21NS120022
Keywords: Pediatric, Microglia, Inflammation/Immune Function, Cerebral Blood Flow
ROLE OF MLKL AND INFLAMMASOME IN CHRONIC BLOOD BRAIN BARRIER DAMAGE AFTER CONTROLLED CORTICAL IMPACT
1MGH, Charlestown MA, United States
Persistent blood‐brain barrier (BBB) damage contributes to cognitive impairment and neuronal loss in aging and neurodegenerative diseases. Dysfunction of BBB after traumatic brain injury (TBI) has been proposed to cause neurodegeneration, but mechanisms that underlie how BBB damage is initiated and maintained are completely unknown. It is important to understand the cellular and molecular mechanisms of how TBI perpetuates chronic BBB damage. Mixed lineage kinase domain‐like protein (MLKL) is a key effector protein of necroptotic cell death and upstream regulator for inflammasome activation. Using a model of cerebral contusion in mice, we show that
(1) BBB damage in the acute phase of CCI resolves by one week and is re‐established by two weeks and persists through at least two months after injury; (2) mice deficient in MLKL (MLKL‐/‐) have significantly reduced BBB damage at 2 months after CCI compared to wild type (WT); (3) inflammasomes are persistently activated at 2 months in injured brain regions with BBB permeability and in brain endothelial cells isolated from injured hemispheres; (4) BBB damage is markedly reduced in caspase‐1/11‐/‐ (inflammasome deficient) mice. These data strongly support the idea that MLKL and inflammasome activation are targetable drivers of chronic BBB damage after CCI.
Keywords: Blood Brain Barrier, Vascular, Inflammation/Immune Function
TLR4 INHIBITION WITH C34 FAVORABLY AFFECTS NORMAL ASTROCYTIC FUNCTION FOLLOWING TRAUMATIC BRAIN INJURY ALLOWING MYELIN REGENERATION AND IMPROVED NEUROCOGNITIVE OUTCOMES
1Johns Hopkins University, Baltimore MD, United States
Astrocytes play several key roles in traumatic brain injury (TBI), including scar formation and microglial activation. To investigate the role of astrocytes in TBI‐induced neuroinflammation, we used a novel TLR4 inhibitor (C34).
A murine controlled cortical impact model was utilized, whereby the left parietal lobe was injured after craniotomy then analyzed at post injury day (PID) 1, 7, 28. The experimental groups are: C57Bl (CTRL), C57Bl treated with C34 intraperitoneally (C34). Morris Water Maze (MWM) was used to assess neurocognitive outcomes. Real‐time PCR (qPCR) was used to quantify gene expression associated with astrocytic activation. Fixed frozen cortical samples were sectioned, stained for MBP and DAPI then imaged. Student's T‐test and One‐way ANOVA were used for statistical analysis with significance achieved when p < 0.05.
On qPCR, C34 group showed increased expression of the astrocytic activation marker GFAP at PID1 compared to CTRL (1882+/‐332.4, 980.6+/‐146.1 respectively). By PID28, the expression of GFAP (608.4+/‐44.12, 750.4+/‐60.85 respectively) and NG2 (17.31+/‐1.788, 24.37+/‐2.052 respectively) in C34 group was lower than CTRL. On MWM, C34 group had more platform entries (1.8 +/‐ 1.67) than CTRL (0.4 +/‐ 1.1). On IHC, C34 group revealed GFAP expression around the lesion was increased then attenuated sooner. MBP staining revealed progressive myelin growth into the lesion by PID28.
Activated astrocytes are crucial in TBI pathogenesis, and modulation through TLR4 inhibition with C34 leads to earlier astrocytic activation and promotes myelin regeneration. It is possible that C34 decreases late reactive gliosis offering improved neurocognitive outcomes, highlighting C34 as a novel therapy for TBI.
Keywords: Neuroprotection, Astrocyte, Axonal Injury, Concussion/mTBI, Therapeutics/Drug Discovery, Inflammation/Immune Function
MILD TRAUMATIC BRAIN INJURY PHENOTYPES FOLLOWING CLOSED HEAD INJURY IN RATS
1Uniformed Services University, Rockville MD, United States
Keywords: Biomarker, Behavioral Function, Concussion/mTBI, Inflammation/Immune Function
EFFECTS OF DEVELOPMENTAL RESTRICTION ON NEURAL PROGENITOR GRAFT COMPOSITION AND RECOVERY OF FUNCTION FOLLOWING SPINAL CORD INJURY
1Texas A&M University, College Station TX, United States
Neural progenitor cell (NPC) transplantation has shown high therapeutic potential following spinal cord injury (SCI). However, there is limited understanding of how distinct subtypes of graft‐derived neurons can support reestablishment of specific spinal circuitry. We have previously reported that NPCs from restricted regions of the embryonic rodent spinal cord differ in their dorsal/ventral neuronal identities upon maturation. We now show that the developmental stage of donor NPCs also significantly influences the neuronal subtypes populating mature grafts. In this study, donor NPCs were isolated from mouse embryonic spinal cords at E11.5, E12.5, and E13.5 and transplanted into sites of SCI (C4 dorsal column lesion). Four weeks post‐transplantation, tissue was collected and analyzed using various neuronal cell type markers. We found that earlier‐stage grafts were enriched for ventral/motor neurons. Conversely, later‐stage grafts were enriched for dorsal/sensory neurons. Interestingly, this temporal effect on graft phenotype closely mirrors neurogenic ‘peaks' differentially exhibited by distinct neural progenitor subtypes during normal spinal cord development and suggests that different NPC developmental stages may be better suited for restoration of motor or sensory functions damaged by injury to the spinal cord. The latter is currently being investigated in ongoing work examining the effects of NPC developmental restriction on graft‐host connectivity and recovery of function following transplantation into the lesion site in a mouse model of spinal contusion.
Keywords: Behavioral Function, Stem Cells, Transplantation, Regeneration & Plasticity
REPEATED MILD TRAUMATIC BRAIN INJURY IMPAIRS LONG‐TERM DEPRESSION OF SYNAPTIC EFFICACY IN THE HIPPOCAMPUS.
Miss Cristina Pinar, Miss Christine Fontaine, Mr. Juan Trivino ‐ Paredes,
1University Of Victoria, Victoria, Canada
Traumatic Brain Injury (TBI) is a global health problem and concussion, or mild TBI (mTBI), accounts for up to 75% of all brain injuries occurring annually in the US. There is also growing evidence indicating that repeated mTBI (r‐mTBI) can result in cumulative neuropathology and behavioural deficits. In this study we used an awake closed head injury (ACHI) model to administer an mTBI repeatedly (8 times) over a 4 day period in juvenile male and female rats (P25‐28). At 1 or 7 days after the last injury, hippocampal slices were prepared for in vitro electrophysiological recordings, and the capacity for long‐term depression (LTD) was examined in the medial perforant path (MPP)‐dentate gyrus (DG) synapse. We found that r‐mTBI did not produce significant alterations in presynaptic neurotransmitter release or in the size of fEPSPs generated with different stimulus intensities. In contrast, r‐mTBI significantly impaired the capacity for LTD in both sexes, an effect that developed over a period of days. These data are the first to describe the negative impact of r‐mTBI on LTD in the juvenile DG in both males and females, and provide evidence for the delayed development of neurological deficits with r‐mTBI.
Keywords: Neurotransmitter, Cognition/Learning/Memory, Concussion/mTBI, Spasticity
GUT MICROBIAL TRANSPLANTATION RESTORES THE GASTROINTESTINAL MICROBIAL POPULATIONS FOLLOWING A TRAUMATIC BRAIN INJURY IN A PEDIATRIC PORCINE MODEL
1Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens GA, United States, 2Neuroscience Program, Biomedical and Health Sciences Institute, Athens GA, United States, 3Regenerative Bioscience Center, University of Georgia, Athens GA, United States, 4Department of Foods and Nutrition, College of Family and Consumer Sciences, University of Georgia, Athens GA, United States
Annually 400,000 children in the US are treated for traumatic brain injury (TBI), with 3,000 dying; however, currently there is no FDA‐approved therapeutic. The microbiome‐gut‐brain axis (MGBA) is potentially a novel therapeutic target to modulate secondary injury following TBI. The objective of this study was to determine the potential of gut microbial transplantation (GMT) to restore TBI‐induced gut microbiota alterations to pre‐injury populations utilizing a pediatric porcine model. Moderate/severe controlled cortical impact TBI was induced in four‐week‐old, crossbred piglets that were then administered a GMT (n = 6) or saline solution (CON, n = 6) by oral gavage 2‐hours post injury and every 24 hours for seven days. Sham (S, n = 6) control animals only received a craniectomy. MRI data were collected 1‐day (1D) and 7‐days (7D) post‐injury. Fecal samples were collected pre‐injury and 1D, three‐days (3D), and 7D post‐injury. Cecal samples were collected 7D post‐injury. Fecal and cecal microbial populations were identified using 16S rRNA gene sequencing. Lesion volume decreased in GMT piglets from 1D to 7D (P = 0.005). Cecal Lactobacillus coleohominis and Lactobacillus pontis increased in GMT piglets (P ≤ 0.018) compared to CON and S piglets. Fecal Actinobacillus, Actinobacillus indolicus, Actinomyces howellii, and Bifidobacterium increased in CON pigs at 1D (P ≤ 0.048). Erysipelotrichaceae_UCG‐006 and Streptococcus hyointestinalis increased on 1D and 3D, respectively, in CON piglets (P ≤ 0.034) before returning to baseline on 7D. These results suggest an acute increase in potentially harmful bacteria following a TBI that can be corrected by GMT, thus lessening the severity of pediatric TBI.
Keywords: Pediatric, Secondary Injury, Imaging, Therapeutics/Drug Discovery
MODULATING BLAST INTENSITY AND INJURY SEVERITY IN A NOVEL RODENT MODEL OF BLAST‐INDUCED TBI
1University of Nevada Las Vegas, Las Vegas NV, United States
Cell death following extensive damage can become necrotic and dysregulated, spreading into neighboring healthy tissue. Injured tissue following blast‐induced traumatic brain injuries (bTBIs) undergoes a rapid spread of heterogeneous, necrotic processes that determine the severity of the injury from mild to severe. Post‐injury outcomes including permanent neuronal circuit alterations and glia activation are associated with the severity of the injury, but the precise mechanisms contributing to the heterogeneity of symptoms are not well understood. Modeling bTBI is difficult due to the low availability of rodent models or the use of extensive apparatus. Models possessing multiple levels of validity, including face and content validity are key to expanding our understanding of the pathological effects of injury following a blast. Blast parameters including intensity, recurrence, and the culmination of blast wave lead to differences in necrotic cell death signaling and heterogeneity of symptoms. Effective experimental modeling will cause neuronal cell death at various degrees and allow us to investigate the interplay between the blast parameters, cell death, and symptoms. This novel model generated blast ranging from 50 psi to 120 psi that caused differential injury severity localized to a single hemisphere using a single apparatus. At higher pressures, the injury volume was larger with a smaller peri‐injury area in comparison to lower pressures. Controlling mild to severe injury will further our understanding of the pathological mechanisms following injury prompting the creation of effective interventions for bTBIs slowing and/or eliminating the development of neurodegenerative disorders such as chronic traumatic encephalopathy.
Keywords: Blast, Cell Death
NONINVASIVE PERFUSION MRI PREDICTS FUNCTIONAL OUTCOME FOLLOWING RODENT CERVICAL SPINAL CORD INJURY
1Medical College Of Wisconsin, Milwaukee WI, United States, 2Clement J Zablocki Veteran's Affairs Medical Center, Milwaukee WI, United States
Optimizing spinal cord tissue perfusion after traumatic spinal cord injury (SCI) is a goal in the acute setting, however, a noninvasive measurement of perfusion remains an unmet need. This project combined perfusion (PWI) and diffusion weighted (DWI) MRI to compare the status of the hemodynamics and microstructure, respectively, in acute SCI.
Adult Sprague‐Dawley rats received a cervical contusion injury of varying injury severity (injured = 30, sham = 9). MRI was performed at 4‐ and 48‐hours post‐SCI and included T1, T2, and T2* weighted imaging, with T2 images at 12 weeks to measure chronic lesions. Functional outcomes were assessed with the Forelimb Locomotor Assessment Scale (FLAS). Acute PWI and DWI thresholds were derived using spatial registration to predict chronic lesions. Acute lesion volumes were subsequently compared to functional outcomes.
At 4 hours post injury, perfusion (197 ± 112μm3) and diffusion (208 ± 75μm3) lesion volumes were similar. However, at 48 hours, diffusion lesions expanded (333 ± 119μm3), whereas perfusion lesion contracted (142 ± 96μm3). Perfusion lesion volumes at 4 hours were the stronger predictors of chronic functional outcomes (R2adj = 0.47, p < 0.001) compared to perfusion at 48 hours (R2adj = 0.29, p = 0.003). In contrast, diffusion lesions at 48 hours (R2adj = 0.39, p < 0.001). were stronger predictors of chronic function compared to 4 hours (R2adj = 0.22, p = 0.011). At 4 hours, perfusion was also stronger predictor of outcome than conventional measures of T2 and T1.
These results indicate that perfusion deficits were pronounced acutely after SCI, predicted long‐term outcome, and recovered considerably by 48 hours. The results highlight the unique information provided by perfusion and diffusion MRI early after SCI.
Keywords: Biomarker, Imaging, Cerebral Blood Flow
ONE‐YEAR EFFICACY AND SAFETY OUTCOMES IN PATIENTS WITH CHRONIC TRAUMATIC BRAIN INJURY: FINAL ANALYSIS OF THE PHASE 2 STEMTRA TRIAL
1Neurotrauma Rehab Comsultants LLC, Littleton CO, USA, 2University of Pittsburgh Medical Center, Pittsburgh PA, USA, 3Stanford University School of Medicine, Stanford CA, USA, 4Hokkaido University Hospital, Sapporo, Japan, 5JCHO Tokyo Shinjuku Medical Center, Tokyo, Japan, 6Okayama University Hospital, Okayama, Japan, 7University of California, San Francisco, San Francisco CA, USA, 8New York University and NYU Langone Medical Center, New York NY, USA, 9Loma Linda University Medical Center, Loma Linda CA, USA, 10SanBio, Inc., Mountain View CA, USA, 11Yale University, New Haven CT, USA
Keywords: Stem Cells, Concussion/mTBI, Transplantation
INVESTIGATING THE RELATIONSHIP BETWEEN VASCULATURE DISTRIBUTION AND NEURONAL PERMEABILITY FOLLOWING REPETITIVE DIFFUSE TBI IN SWINE
1University Of Pennsylvania, Philadelphia PA, United States, 2Corporal Michael J. Crescenz VA Medical Center, Philadelphia PA, United States
Closed‐head diffuse TBI, the most common form of clinical TBI, results in diffusely distributed neuropathology. We previously reported that plasmalemmal damage to neuronal somata and dendrites was a primary feature following diffuse TBI in our porcine model. The current study, sought to contextualize neuronal permeability changes based on anatomical features in the midbrain, paying particular attention to proximity to vasculature, referred to as “perivascular domains”. Pigs were subjected to single or repetitive moderate‐to‐severe, closed‐head rotational‐acceleration injury in the sagittal plane to induce diffuse TBI. We utilized the cell impermeable dye, Lucifer yellow (LY), to label mechanically permeabilized neurons during a sham, single, or repetitive injuries separated by 15 minutes, 3 days, or 7 days. The quantity of LY+ neurons in the ventral portion of the midbrain increased in repetitive injuries separated by 3 days relative to all other conditions or midbrain regions (p < 0.05). Surprisingly, we also found a reduction in the number of larger (≥100μm diameter) and mid‐sized (50‐99.9μm), but not smaller (0‐49.9μm), blood vessels in the midbrains of animals subjected to repetitive injuries separated by 3 days (p < 0.05). Finally, the density of LY+ neurons was not preferentially distributed in perivascular domains relative to regions further from blood vessels in the midbrain under these injury conditions. Together, these data suggest co‐occurring changes in vasculature and neuronal permeability following closed‐head diffuse TBI. Future studies will aim to understand the cause and implications of seemingly transient blood vessel loss and/or contraction following TBI and the relationship with repetitive injuries.
Keywords: Vascular, Neuropathology
RAPID PREDICTION OF SECONDARY NEUROLOGIC DECLINE AFTER TRAUMATIC BRAIN INJURY: A DATA ANALYTIC APPROACH TO THE GOLDEN HOUR
Dr. Jamie Podell1, Dr. Shiming Yang1, Ryan Felix1, Dr Catriona Miller, Dr. Gunjan Parikh1, Dr Hegang Chen1, Yi‐Mei Kuo1, Chien Yu Lin1, Dr. Peter Hu1,
1Univ Of Maryland School of Medicine, Baltimore MD, United States
Keywords: Secondary Injury, Concussion/mTBI, Computational/Modeling, Neurocritical Care, Informatics
REPETITIVE MILD TRAUMATIC BRAIN INJURY INCREASES TAU PHOSPHORYLATION, CYTOKINE EXPRESSION, AND PHOSPHO‐PROTEIN SIGNALING IN THE 3XTG MOUSE MODEL OF ALZHEIMER'S DISEASE
1Georgia Institute Of Technology, Atlanta GA, USA, 2Emory University, Atlanta GA, USA
Repeated mild traumatic brain injuries (mTBIs) sustained within a “window of vulnerability” can lead to a cumulative severity of outcomes. We previously reported that acute increases in neural immune signaling were linked to worse cognitive outcome in a weight‐drop mouse model of repetitive mTBI. We hypothesized that an increasing number of injuries would drive neural immune signaling, pathology, and glial activation.
Female 3xTg mice at 3‐4mo of age were subjected to 1x, 3x, or 5x weight‐drop closed head injuries (CHI) spaced once‐daily and brains were harvested at 30min, 4h, or 24h after the final CHI (n = 7‐10/time point/injury group). 32 cytokines, 10 MAPK phospho‐proteins, phospho‐tau (pThr181), and total tau were measured by Luminex. GFAP was measured by ELISA.
Total tau and phospho‐tau were significantly increased in the hippocampus 30min after 5xCHI (p = 0.004, p = 0.007). We used hierarchical clustering to identify groups of coordinated phospho‐proteins and cytokines among all sham/injury groups and found that certain cytokines (RANTES, MIP‐1a, IL‐4) and phospho‐proteins (pStat3, pJnk, pHSP27) were associated with elevated GFAP while others were associated with phospho‐tau (VEGF, IL‐13, IL‐17). Noting within‐group heterogeneity, we conducted a regional ratio analysis to identify cortical differences accentuated with respect to the hippocampus, finding that several pro‐inflammatory cytokines (IP‐10, KC, IL‐17; p = 0.01, p = 0.002, p = 0.04) were significantly up‐regulated 24h after 3xCHI. GFAP was upregulated 30min after 5xCHI (p = 0.005).
Together, our data identify different groups of cytokines associated with phospho‐tau, GFAP, and repetitive injury, suggesting distinct immune signaling pathways are associated with tau pathology, astrocyte reactivity, and injury response.
Keywords: Concussion/mTBI, Inflammation/Immune Function, Cerebral Blood Flow, Neuropathology
INTRAVENOUS IRON ADMINISTRATION RESULTS IN CEREBRAL EDEMA EXPANSION
1The University of Texas Health Science Center at San Antonio, San Antonio TX, United States
Iron plays an important role in the development of perihematomal edema in the setting of intracerebral hemorrhage (ICH). Cerebral iron is increased via direct hemoglobin release in ICH. Several‐studies have investigated using iron‐chelating agents to mitigate its toxicity, however the effect of systemic iron administration, corroborating the reverse concept, has never been reported clinically. Herein, we report the first case of systemic iron administration in the setting of hemorrhagic traumatic brain injury (TBI).
A 46‐year‐old woman was admitted to the hospital with acute TBI. Her head CT scan showed bifrontal hemorrhagic contusions. She was started on hyperosmolar therapy and her condition remained stable. She was found to be anemic and was given intravenous iron sucrose. Shortly after iron administration, her mental status declined, and left pupil became dilated and sluggish. Repeat CT demonstrated significantly worsening pericontusional edema. This prompted maximum hyperosmolar therapy and external ventricular drain (EVD) placement. Therapy was weaned slowly due to highly liable ICPs. She was discharged home after a 25‐day hospital stay. We believe this is the first report of significant worsening perihematomal edema alongside clinical decline after intravenous iron administration in the setting of acute hemorrhagic TBI.
Administration of systemic iron in acute TBI may be detrimental. The effects of systemic iron administration on brain edema, and the treatments targeting cerebral iron are poorly understood. More research is needed to find effective treatments for iron toxicity in TBI. Our case adds to the growing evidence for such a pathway in treatment of ICH and TBI.
Keywords: Edema, Hemorrhage, Therapeutics/Drug Discovery, Metabolism/Energetics
EXACERBATION OF NEUROINFLAMMATORY GENE EXPRESSION BY EARLY LIFE STRESS AND MILD TBI
1Miami project Cure to Paralysis. University of Miami Miller School of Medicine, Miami FL, United States, 2Neurological Surgery Department. University of Miami Miller School of Medicine, Miami FL, United States
Although the majority of people with mild traumatic brain injury (mTBI) recover rapidly, some have chronic symptoms such as cognitive dysfunction. One risk factor for prolonged recovery after mTBI is chronic stressful life experiences. A key mechanism linking chronic early life stress (ELS) to neurological problems in adulthood is neuroinflammation. We hypothesized that ELS is a risk factor for prolonged cognitive dysfunction after mTBI by increasing neuroinflammation. The rat pups were maternally separated 3hrs daily from P2‐P14 and young adulthood received a fluid percussion brain injury or sham surgery. We found that ELS worsened recovery after mTBI by significantly increasing microglia numbers within the hippocampus. Using qPCR to assess inflammatory signaling molecules in the hippocampus at 24 after mTBI revealed that the combination of ELS+mTBI increased levels of HMGB1, IL‐18, TLR4, NLRP3, caspase‐1 and IL‐1β mRNA levels. This regulation was persistent and NLRP3 levels remained elevated up to 2‐months after mTBI‐ELS. Treatment with the NLRP3‐inflammasome inhibitor MCC950 reduced mRNA levels of NLRP3 and IL‐1β. Using fluorescence‐activated‐cell‐sorting to isolate microglia, we observed a significant increase in NLRP3 in Sham+ELS, mTBI+Ctl and mTBI+ELS. However, IL‐1β levels only significantly increased with mTBI+ELS. IL‐1β upregulation was NLRP3‐dependent as MCC950 reduced IL‐1β and NLRP3 levels within microglia. Moreover, ELS prior to mTBI significantly impaired contextual fear conditioning, and this was prevented with MCC950 treatment. In summary, ELS limits recovery after mTBI by activating the NLRP3‐inflammasome in microglia, and inhibition of NLRP3 could be a potential therapeutic for treating chronic cognitive deficits after ELS and mTBI.
Keywords: Post‐Traumatic Stress, Concussion/mTBI, Inflammation/Immune Function, Neuropathology
NON‐INVASIVE VAGUS NERVE STIMULATION AS AN APPROACH TO TREATMENT OF TBI & STROKE?
1Arkansas Tech University, Russellville AR, United States, 2University of Arkansas for Medical Sciences, Little Rock AR, USA
Treatment of traumatic brain injury and stroke with invasive vagus nerve stimulation has been of interest over the past two decades with experimental evidence providing support for the efficacy in motor and cognitive recovery. Vagus nerve stimulation is thought to exert its beneficial effects by altering synaptic NE in the terminal fibers of the locus coeruleus. Vagus nerve stimulation has notable advantages over other treatments, namely its non‐pharmacological nature and the presumed ability to modulate dosage via altering stimulus frequency and intensities. Nonetheless, a significant limitation of VNS is that it is invasive, requiring the implantation of the stimulator and stimulating electrodes at the carotid level of the vagus. More recently, fibers of the vagus projecting to the near the surface of the auricle region of the ear have been identified raising the question: can transcutaneous VNS activate the same pathway as does traditional VNS, and do so with sufficient strength to be physiologically meaningful? To test this question, we transcutaneously stimulated the auricle region of healthy individuals and monitored changes in EEG alpha power. Suppression of EEG alpha would be expected with increased synaptic NE. When compared to baseline, we observed statistically significant reduction (< p 0.05) in both right and left occipital, parietal region electrodes, & right Temporal electrodes. Frontal and left temporal electrodes did not produce reduction in EEG Alpha. These data are consistent with the hypothesis that tVNS is capable of activating similar pathways as does cVNS and at a magnitude sufficient to be of interest.
Keywords: Rehabilitation, Neuroprotection, Secondary Injury, Neurotransmitter, Cognition/Learning/Memory, Epilepsy/Seizure, Regeneration & Plasticity, Neurocritical Care
LONG‐TERM CHARACTERIZATION OF THE LOCAL SPINAL IMMUNE RESPONSE IN MICE SUBJECTED TO CONTUSIVE SPINAL CORD INJURY
1Department of Neurosurgery, Rush University Medical Center, Chicago IL, United States
Traumatic spinal cord injury is rapidly followed by a robust, local immune response within the spinal cord, consisting of activation of central nervous system resident immune cells and infiltration by peripheral immune cells. This local immune response persists chronically and is widely recognized to hold considerable sway over the progression of secondary tissue damage. As the majority of spinal cord injury sufferers live with chronic injuries, studies examining chronic spinal cord inflammation are warranted, yet they are much fewer in number than studies of acute and subacute inflammation. We present an extensive, long‐term characterization of the local post‐injury immune response in female wild type (C57BL/6) mice, following a moderate (50 kdyn) spinal cord contusion. Multiple terminal assessment timepoints are included, ranging from 1 day to 180 days post‐injury. The relative levels of certain T cell subsets (helper T cells, cytotoxic T cells, regulatory T cells), as well as macrophages and microglia, are monitored via flow cytometry. By applying standard measures of locomotor and sensory function at each of the terminal timepoints, we are able to identify any correlations between the progression of the local immune response and behavioral recovery. At 180 days post‐injury, we observe elevated levels of all measured cell types in injured animals, relative to sham controls, most notably, a 5‐fold increase in the number of observed regulatory T cells.
Keywords: Secondary Injury, Inflammation/Immune Function
ALZHEIMER'S DISEASE ACCELERATES SYNAPTIC DYSFUNCTION AND LEARNING AND MEMORY DEFICITS AFTER MILD TRAUMATIC BRAIN INJURY
1Miami project Cure to Paralysis. University of Miami Miller School of Medicine, Miami FL, United States, 2Neurological Surgery Department. University of Miami Miller School of Medicine, Miami FL, United States
Traumatic brain injury (TBI) and Alzheimer's disease (AD) are significant public health problems. TBI is an environmental risk factor for AD. The molecular mechanisms that link TBI to the development of AD remain unclear. A common pathology for TBI and AD is synaptic loss, which contributes to cognitive deficits and neuroinflammation. TBI exacerbates cognitive deficits in AD, however whether these cognitive deficits are mediated by an acceleration of synaptic dysfunction and loss is unknown. In this study, we determined if synaptic dysfunction and loss were worsened after TBI in the context of developing AD prior to AD‐associated cognitive deficits. B6C3 wild type and APP/PS1 mice received mild controlled‐cortical impact (CCI) or sham surgery at 2‐month of age. The injury severity was selected to be mild (0.55 mm depth, 2 m/sec), which does not impair hippocampal synaptic transmission or learning and memory in wild type mice. Hippocampal slices from the ipsilateral side were prepared at 2‐month post‐surgery. We found that basal synaptic transmission was depressed in slices from APP/PS1 mice after CCI as compared to APP/PS1‐sham mice. Slices were tetanized with high frequency stimulation. LTP was impaired in slices from APP/PS1‐CCI mice, but not in slices from APP/PS1‐CCI mice or wild type‐CCI mice. To assess cognition, mice received contextual fear conditioning at 2‐month post‐surgery. APP/PS1‐CCI mice exhibited significantly less contextual fear conditioning as compared to APP/PS1‐sham, wild type‐CCI, and wild type‐sham mice. These data suggest that TBI results in synaptic dysfunction and learning and memory deficits in an AD mouse model.
Keywords: Behavioral Function, Cognition/Learning/Memory, Synaptic Function, Neuropathology
EXOGENOUS MITOCHONDRIAL SUPPLEMENTATION TO THE INJURED SPINAL CORD VIA ENGINEERED ERODIBLE HYDROGELS
1Spinal Cord & Brain Injury Research Center (SCoBIRC), Department of Physiology, University Of Kentucky, Lexington KY, United States, 2Department of Chemical and Materials Engineering, University of Kentucky, Lexington KY, United States, 3Department of Chemistry, University of Kentucky, Lexington KY, United States, 4VA Medical Center, Lexington KY, United States, 5Spinal Cord & Brain Injury Research Center (SCoBIRC), Department of Neuroscience, University Of Kentucky, Lexington KY, United States
Spinal cord injury elicits widespread mitochondrial damage that leads to increased oxidative stress and inflammation. Replacement of dysfunctional mitochondria with healthy exogenous mitochondria via intraspinal injections after injury improves mitochondrial bioenergetics after 24hr, but not functional improvement. Because this might be attributed to technical limitations of needle tract damage, accumulation at injection sites, and reduced mitochondrial integrity extracellularly, we developed in a minimally invasive subdural delivery route utilizing thermogelling erodible hydrogels that can be fabricated to degrade at a controlled rate in vivo to deliver healthy mitochondria in and around the injury site. Initial studies employed established cell lines to optimize an ideal hydrogel composition. A hydrogel composed of methylcellulose (1%) and hyaluronic acid (1%) promoted greater integrity of isolated mitochondria for ∼1 hour at 37°C. Using SH‐SY5Y cells with genetically modified RFP‐tagged mitochondria, uptake into unlabeled host cells was monitored with confocal microscopy to confirm internalization within 30 minutes, with time‐dependent increases in uptake up to 24 hours. The presence of human mitochondrial DNA (mtDNA) was used to verify internalization of exogenous human mitochondria transplanted into rat PC‐12 cells two hours after incubation, and in naïve rat spinal cord 24 hours after intraspinal vs subdural mitochondrial transplantation. The extent mitochondrial uptake was highly varied between delivery methods, as well as rostro‐caudal dispersion with respect to the site of delivery. Ongoing experiments are assessing the dose‐ and time‐dependent effects of intraspinal vs subdural mitochondrial delivery on cellular bioenergetics and cell‐specific internalization.
Support: SCoBIRC Chair Endowments (AGR&PGS); DoD W81XWH2010347(AGR); NIH‐R01 NS119337(AGR&SPP)
Keywords: Therapeutics/Drug Discovery, Transplantation
SEX‐DEPENDENT TIMELINES OF MITOCHONDRIAL LOSS AND MITOPHAGIC ACTIVITY AFTER TRAUMATIC BRAIN INJURY
1UCLA Neurosurgery, Los Angeles CA, United States, 2UCLA Brain Injury Research Center, Los Angeles CA, United States
Traumatic brain injury's excitotoxic, oxidative, and ischemic sequelae produce acute mitochondrial dysfunction and alter energy metabolism. These deficits follow sex‐dependent timelines. While female rats return to sham‐like respiratory control 24hr after moderate controlled cortical impact (CCI), dysfunction persists until 10d in males. Returning respiratory function could reflect removal of dysfunctional mitochondria through cell death or mitochondria‐specific autophagy. Mitophagic activity may vary by sex, with females exhibiting a shorter period of mitochondrial loss. Mitochondria were isolated from ipsilateral hippocampus and pericontusional cortex of adult female and male rats 6hr, 24hr, 3d, and 10d following CCI, or after sham craniotomy. Mitochondrial mass was quantified in isolated samples with MitoTracker Green. Expression of proteins involved in mitochondrial fission (Drp1), fusion (OPA1, OMA1) and autophagosome recruitment (PINK1, Parkin) were measured via western blot. MitoTracker fluorescence increased in injured males' cortical samples to 153% sham by 10d and peaked in female cortex 24hr post‐CCI at 184% sham before returning to sham levels by 10d. Increased fluorescence indicated lower mitochondrial content. Parkin, PINK1, and Drp1 expression decreased post‐injury in cortical mitochondria, suggesting increased mitophagic degradation, before returning to sham levels in females by 10d. Injury increased both sexes' ratios of inactive OMA1 to short‐chain OMA1, active in OPA1 cleaving, while OPA1 expression decreased only in males. Results support a sex‐dependent timecourse for mitochondrial loss post‐injury with earlier repopulation in females.
Keywords: Secondary Injury, Metabolism/Energetics
REDOX PRECONDITIONING OF MITOKATP BY ESTRADIOL ALLEVIATES MITOCHONDRIAL DYSFUNCTION AFTER TRAUMATIC BRAIN INJURY
1UCLA Neurosurgery, Los Angeles CA, United States, 2UCLA Brain Injury Research Center, Los Angeles CA, United States, 3Great Lakes Institute of Technology, Erie PA, United States
Mitochondrial dysfunction incites secondary injury after traumatic brain injury (TBI) by altering energy metabolism and reactive oxygen species (ROS) production. Metabolic recovery after TBI in rats follows sex‐dependent timelines. Females recover sham‐level mitochondrial respiration 24hr post‐injury without increased ROS production, while males retain respiratory deficits and greater ROS generation up to 10d post‐injury. Hormone mediation of metabolism may inform these differences. Estradiol (E2) promotes ROS‐producing fatty acid oxidation (FAO), while thiol oxidation facilitates opening of the putative MitoKATP channel (CCDC51). In females, ROS from FAO may “pre‐condition” MitoKATP, helping mitochondria buffer ionic changes post‐TBI. Adult female and male rats were respectively dosed with ER⍺ antagonist methyl piperidinopyrazole (MPP) or E2 24hr before and immediately following controlled cortical impact (CCI). Respiration, ROS production, FAO, mitochondrial membrane polarization, and CCDC51 thiol oxidation were assessed in pericontusional cortex 24hr post‐injury. Vehicle‐treated sham females exhibited no mitochondrial deficits and higher FAO than vehicle sham males. MPP alone reduced females' ROS production and FAO while increasing depolarization. With injury, MPP reduced females' mitochondrial function. E2 treatment increased males' FAO and protected against CCI for mitochondrial respiration, ROS, and FAO. CCDC51 thiol oxidation was higher in females than males. MPP treatment increased females' CCDC51 thiol reduction while E2 modestly decreased reduction in males. By stimulating redox signaling to activate MitoKATP and buffer hyperpolarization, E2 preconditioning may ameliorate mitochondrial dysfunction post‐TBI.
Keywords: Neuroprotection, Secondary Injury, Endocrine, Metabolism/Energetics
THE RISK ANALYSIS INDEX PREDICTS POST‐OPERATIVE MORTALITY & NON‐ROUTINE DISCHARGE BETTER THAN THE 5‐FACTOR MODIFIED FRAILTY INDEX AFTER NEUROSURGICAL INTERVENTIONS IN TRAUMATIC BRAIN INJURY
Ms. Rachel Thommen1, Mr. Matt Conlon1, Mr. John Vellek1, Dr. Syed Faraz Kazim2, Dr. Meic Schmidt2, Dr. Rohini McKee2,
1New York Medical College, Valhalla NY, USA, 2University of New Mexico Department of Neurological Surgery, Albuquerque NM, United States
Keywords: Rehabilitation, Concussion/mTBI, Intracranial Pressure, Consciousness
MITOCHONDRIAL DYSFUNCTION IN ASTROCYTES FOLLOWING PRIMARY BLAST TRAUMATIC BRAIN INJURY
1Virginia Tech, Translational Biology, Medicine, and Health Graduate Program, Roanoke VA, United States, 2Virginia Tech, Department of Biomedical Engineering and Mechanics, Blacksburg VA, United States, 3Salem Veterans Affairs Medical Center, Salem OR, United States
Astrocyte reactivity is a common pathology following blast‐induced traumatic brain injury (bTBI) and mitochondrial dynamics (fission and fusion) may be contributing to this phenotype. Current literature investigates the role of neuronal mitochondria post‐bTBI, however, changes in astrocyte‐specific mitochondrial fission and fusion have not been explored. Therefore, this study aims to characterize changes in astrocytic mitochondrial dynamics at seven days after blast exposure and evaluate its potential contribution to astrocyte reactivity. Adult male Sprague Dawley rats were exposed to a single blast overpressure (17psi) in the Virginia Tech Advanced Blast Simulator to re‐create free‐field blast exposure. Following injury, hippocampal astrocytes were isolated using the magnetic‐activated cell sorting technique (MACS) and underwent protein quantification and mRNA expression analysis. At seven days post‐bTBI, western blotting analysis revealed a significant increase in the pro‐fission protein DRP1 (p < 0.05) and a trending increase (p ≤ 0.1) of the DRP1 phosphorylated form at Ser616 (p‐DRP1ser616), where p‐DRP1ser616 is required to initiate mitochondrial fission. Furthermore, western blotting and immunohistochemistry revealed a significant increase in intermediate filament glial fibrillary acidic protein (GFAP) levels, indicating a reactive astrocyte phenotype in the hippocampus at seven days post‐bTBI. These findings indicate mitochondrial fragmentation may be elevated resulting from the increased pro‐fission protein DRP1 and could be correlated with detrimental astrocyte reactivity characteristics at seven days. Future work will further investigate therapeutic approaches targeting astrocyte‐specific mitochondria after blast by assessing the potential influence of DRP1 and p‐DRP1ser616 on the acute astrocytic reactivity at one and three days following blast.
Keywords: Secondary Injury, Astrocyte, Blast, Concussion/mTBI
TRAUMATIC BRAIN INJURY CHARACTERISTICS PREDICTIVE OF SUBSEQUENT SLEEP‐WAKE DISTURBANCES IN PEDIATRIC PATIENTS
1Department of Child Health ‐ University of Arizona College of Medicine ‐ Phoenix, Phoenix AZ, United States, 2Phoenix VA Health Care System, Phoenix AZ, United States, 3Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix AZ, United States, 4Department of Integrative Physiology ‐ University of Colorado at Boulder, Boulder CO, United States
Traumatic brain injury (TBI) frequently leads to sleep‐wake disturbances (SWD) but few studies have characterized TBI‐induced SWD in the pediatric population. Here, we sought to determine the prevalence of SWD following pediatric TBI, and to examine characteristics of TBI and patient demographics that could predict subsequent SWD development. We conducted a single‐institution, retrospective review of all patients who were diagnosed with a TBI and subsequently diagnosed with a SWD from the years 2008 – 2019. 207 patients met the inclusion/exclusion criteria and were included in the analyses. Data analyzed included: age at initial TBI, gender, TBI severity, number of TBIs, type of SWD, and time from initial TBI to SWD diagnosis. Multinomial logit and negative‐binomial models were fit to investigate if the multiple types of SWD and the time to onset of SWD following TBI could be predicted by patient variables. We found that distributions of SWD diagnosed after TBI were similar between genders. Probability of insomnia increased with increasing patient age. Older TBI patients had shorter time to SWD onset than younger patients. Patients with severe TBI had the shortest time to SWD onset, whereas patients with mild or moderate TBI had comparable times to SWD onset. Multiple TBI characteristics and patient demographics were predictive of a subsequent SWD diagnosis in the pediatric population. This is an important step toward increasing education among providers, parents, and patients about the risk of developing SWD following TBI.
Keywords: Pediatric, Sleep, Behavioral Function, Concussion/mTBI
LONGTERM AND CHRONIC ALTERATION OF NEURONAL ACTIVITY IN FREELY‐BEHAVING MICE AFTER A JUVENILE MILD TRAUMATIC BRAIN INJURY
Dr. Christophe Dubois1, Lea Hippauf1, Richard Rouland1,
1CNRS, Bordeaux, France
Materials & Methods: Seventeen‐day‐old mice were impacted over the somatosensory cortex (SC) to produce jmTBI (Rodriguez‐Grande et al. 2018; PMID:29665077). Neuronal In vivo calcium imaging was performed up to 9 months post‐injury at rest and during behavioral paradigms (novel object recognition, elevated plus maze, beam walk, rotarod and hot plate tests) after miniscope lens implantation and neuronal transfection to express Gcamp6f (n = 5 shams, n = 4 jmTBI).
Keywords: Pediatric, Aging, Imaging, Concussion/mTBI, Synaptic Function, Neuronal‐Glial Interactions, Neuropathology
WHITE MATTER INTEGRITY MODERATES THE ASSOCIATION BETWEEN REMOTE BLAST‐RELATED MILD TBI AND EXECUTIVE CONTROL
1Minneapolis VA Healthcare System, Minneapolis MN, United States
Mild traumatic brain injury (mTBI) is a critical research area in recent combat veterans due to increased prevalence of survived blasts. Post‐mTBI outcomes are highly heterogenous and defining neurological differences may help in discrimination and prediction of cognitive outcomes. This study investigates if white matter integrity, measured with diffusion tensor imaging (DTI), could influence how remote mTBI history is associated with executive control. The sample included 182 veterans from the Minneapolis VA Medical Center who were administered a clinical/TBI assessment, neuropsychological battery, and DTI scan as part of a larger battery. From previous research, five white matter tracts were identified as having a relationship with blast severity: the cingulum, corticospinal tract, inferior fronto‐occipital fasciculus, superior longitudinal fasciculus and uncinate. Fractional anisotropy (FA) of the a priori selected white matter tracts, PTSD severity, and mTBI severity (separated into blast and impact scores) were used as predictors of Trail‐Making Test B (Trails B) performance in a multiple linear regression model. In veterans with history of blast mTBI, the association between blast severity and Trails B was moderated by FA of the right hippocampal cingulum (CGHR), shown by a significant interaction (p = 0.0011), such that lower FA increased the association between blast severity and Trails B. No significant moderation existed for other selected tracts, and the effect was not observed with PTSD in place of mTBI. Analysis showed that investigation at the individual‐tract level may lead to a deeper understanding of neurological differences between blast and impact injuries.
Keywords: Blast, Executive Function, Concussion/mTBI, White Matter
INTERESTING, SURPRISING AND USEFUL PROPERTIES OF NOVEL ANTIBODIES TO NEUROFILAMENT NF‐L
1EnCor Biotechnology Inc, Gainesville GA, United States, 2Department of Neuroscience, University of Florida, Gainesville GA, United States, 3Department of Physical Therapy, University of Florida, Gainesville GA, United States, 4Breathing Research and Therapeutics Center, University of Florida, Gainesville GA, United States, 5McKnight Brain Institute, University of Florida, Gainesville GA, United States
Much interest has focused on the detection of neurofilament subunits as surrogate markers of neuronal injury and degeneration. The neurofilament light chain, NF‐L, can be detected at informative levels in blood and CSF in a variety of CNS injury or degenerative states. We provide a detailed characterization of novel anti human NF‐L antibodies. One class of reagents does not recognize typical NF‐L profiles in healthy neurons and their processes in sectioned material or growing in cell cultures. They instead bind certain NF‐L epitopes which only become accessible to antibodies in degenerating neuronal cells and their processes. Spinal cords from healthy rats show staining with these antibodies in only a very minor subset of presumably spontaneously degenerating processes. In stark contrast, following a mid‐cervical spinal cord contusion injury, these antibodies reveal numerous strongly stained nerve fibers in regions expected to contain compromised processes. Many of these processes appear beaded, sinusoidal or discontinuous as expected for degenerating axons. We have also developed specific antibodies which recognizes a proteolytically labile site in healthy axons which disappears in degenerating processes, allowing positive identification of both healthy and degenerating processes. The unmasking of degeneration specific epitopes appears to be due to proteolysis and can be mimicked by treating sections of healthy tissue with proteases, which results in previously unreactive NF‐L containing profiles becoming strongly reactive with this specific type of NF‐L antibody. These reagents are robust excellent, novel and specific markers of neurodegeneration of wide utility in future studies of CNS disease and injury.
Keywords: Biomarker, Neurodegeneration, Axonal Injury, Diagnostics
CO‐EXPRESSION META‐ANALYSIS OF YOUNG AND AGED MICROGLIA IDENTIFIES UPSTREAM REGULATORS DRIVING NEUROINFLAMMATION AND NEURODEGENERATION IN THE ACUTE TO CHRONIC AFTERMATH OF REPETITIVE MILD TRAUMATIC BRAIN INJURY
1Roskamp Institute, Sarasota FL, United States, 2Open University, Milton Keynes, United Kingdom, 3James A. Haley Veterans' Hospital, Tampa FL, United States
Keywords: Microglia, Neurodegeneration, Gene Expression, Inflammation/Immune Function, Informatics
INFLUENCE OF TBI AND APOE ISOFORMS ON EXTRACELLULAR TAU DYNAMICS AND ELIMINATION FROM THE BRAIN
Dr. Maxwell Eisenbaum1, Arissa Gratkowski1, Dr. Joseph Ojo1, Dr. Fiona Crawford1,2,
1The Roskamp Institute, Sarasota FL, United States, 2James A Haley Veterans Hospital, Tampa FL, United States, 3Bay Pines VA Healthcare System, Bay Pines FL, United States
Keywords: Aging, Neurodegeneration, Blood Brain Barrier, Concussion/mTBI
TAU PROCESSING BY ASTROCYTES IS IMPAIRED AFTER TRAUMATIC BRAIN INJURY IN AN APOE ISOFORM‐DEPENDENT MANNER
1The Roskamp Institute, Sarasota FL, United States, 2James A Haley Veterans Hospital, Tampa FL, United States, 3Bay Pines VA Healthcare System, Bay Pines FL, United States
Keywords: Astrocyte, Neurodegeneration, Concussion/mTBI, Chronic Traumatic Encephalopathy
DEVELOPING A MOUSE MODEL OF SPINAL CORD INJURY INDUCED BOWEL DYSFUNCTION
1University Of Kentucky, Lexington KY, United States
Bowel dysfunction is one of the most prevalent and life‐impacting co‐morbidities associated with spinal cord injury (SCI) with no long‐term treatment available. The extent to which SCI‐induced changes in the colon (e.g. inflammation, fibrosis, and reduced enteric neuron density) cause progressive dysfunction is understudied. There remains a significant unmet need to develop strategies to prevent or reverse bowel dysfunction after SCI. Previous studies have modeled chronic constipation after SCI in rats, however, mouse models of bowel dysfunction after SCI are less prevalent. We hypothesized that a T3 spinal transection would induce chronic functional bowel deficits coincident with colon pathology. Functional bowel deficits were examined through quantification of total transit time (TTT) and fecal pellet counts in the colon to model constipation and potential fecal impaction, respectively. TTT was significantly decreased by 3 days post injury (dpi) in animals receiving SCI compared to sham (laminectomy) injuries. Chronically, at 21 dpi, total fecal pellet count increased in SCI animals compared to those receiving sham injury. Chronic functional deficits measured by fecal pellet count and the presence of fibrosis are consistent with our hypothesis that T3 transection causes chronic bowel dysfunction in mice. Establishing this mouse model will enable further interrogation of cell‐type specific responses and signaling pathways using transgenic models. Determining the extent to which SCI causes pathophysiological changes to the bowel will help develop therapies to improve the lives of individuals with SCI.
Keywords: Secondary Injury, Cell Death
A NOVEL TROPOMYOSIN‐RELATED KINASE‐B (TRKB) RECEPTOR AGONIST PREVENTS VISION LOSS AFTER BLAST OVERPRESSURE INJURY
1Department of Ophthalmology, School of Medicine, Emory University,Atlanta, Atlanta GA, United States, 2Department of Chemistry, Emory University, Atlanta, Atlanta GA, United States
Keywords: Blast, Receptor Mediated/Signaling
THE INFLUENCE OF AGE ON ASTROCYTE AND MICROGLIAL NEUROIMMUNE RESPONSES AFTER TBI
1Georgetown University, Washington DC, United States
Keywords: Secondary Injury, Astrocyte, Microglia, Aging, Neurodegeneration, Inflammation/Immune Function
RNA‐BINDING MOTIF 5 LEVELS ARE DIFFERENTIALLY EXPRESSED IN A SEX DEPENDENT MANNER IN A MURINE MODEL OF NEURONAL MECHANICAL STRETCH‐INJURY
1University Of South Florida, Tampa FL, United States, 2University of Pittsburgh, Pittsburgh PA, United States
RNA‐binding motif 5 (RBM5) is a potent pro‐death tumor suppressor gene. We reported a trend for increased hippocampal survival in female RBM5 knockout (KO) mice after traumatic brain injury (TBI). We also found that females had increased hippocampal estrogen receptor α (ERα) levels vs. injured male KOs which may have influenced neuronal survival. The mechanical stretch‐injury model is a promising tool to further dissect these mechanisms in vitro. To support the study of sex‐dimorphic mechanisms regulating RBM5 in neurons, here we validated a modification to our in vitro mechanical stretch‐injury protocol. Wild‐type (WT) mouse embryos were sex‐dichotomized under a dissecting microscope by visualizing the reproductive organs, and cortices pooled. Tail snips were collected for sex‐determining region Y (SRY) genotyping. Using this methodology, we consistently achieved >90% pure male or female neurons. No sex‐dependent differences were detected in the magnitude of cell death 24h post‐injury, as measured by lactate dehydrogenase release (LDH) or calpain cleavage products. Next, we measured endogenous RBM5 levels. Two‐way ANOVA revealed a significant interaction term (p < 0.0001) between sex and stretch‐injury; RBM5 levels were unaffected by stretch in male neurons but significantly increased in female neurons. In conclusion, we successfully established a protocol to study sex‐dimorphic effects of RBM5 after TBI in vitro. Studies are underway to test if RBM5 KO is neuroprotective in female vs. male neurons using transgenic Rbm5tm1Ozg derived neurons, and to test if 17β‐estradiol preferentially augments RBM5 KO mediated neuroprotection in female vs. male neurons. Support: NIH/NINDS R01NS105721.
Keywords: Neuroprotection, Neurotoxicity, Gene Expression, Cell Death
CHEMOGENETIC SILENCING OF ASCENDING PROPRIOSPINAL NEURONS TO MODULATE AUTONOMIC DYSREFLEXIA
1Spinal Cord & Brain Injury Research Center (SCoBIRC), Department of Physiology, University of Kentucky, Lexington KY, United States
Spinal cord injury above high thoracic levels often results in autonomic dysreflexia (AD), a condition that manifests as acute, episodic hypertension with concurrent bradycardia instigated by massive discharge of sympathetic preganglionic neurons (SPN) in the intermediolateral cell column that are reflexively activated by noxious stimuli below the injury. In addition to loss of supraspinal modulation, the neural circuitry involved in AD includes nociceptive primary afferent C‐fibers, the SPN that trigger the sympathetic response, and ascending propriospinal neurons (APN) that relay the information from the afferent terminals to the SPN.
Maladaptive intraspinal sprouting of nociceptive afferent C‐fibers is associated with AD development, but they do not directly excite SPN, instead communicating with SPN via interneurons. Using chemogenetic tools we aimed to correlate the contribution of APN sprouting with hemodynamic responses during AD. Putative APN reside in the lumbosacral cord with terminals projecting rostrally to thoracic SPN, thus contributing to AD. Accordingly, we selectively and reversibly silenced APN with inhibitory designer receptors exclusively activated by designer drugs at terminals, and the severity of colorectal distension‐induced hypertension was evaluated before, during and after silencing in rats with complete spinal transection. Because of the temporal development of AD, we further compared responses of APN transfected before and after the onset of injury‐induced sprouting (immediate vs delayed). Preliminary results indicate that increased numbers of silenced APN (indicated by mCherry fluorescence) is associated with reduced AD severity, irrespective of immediate vs delayed APN labelling.
Supported Craig H. Neilsen Postdoctoral Fellowship #651019 (FMM), SCoBIRC Chair Endowment (AGR).
Keywords: Regeneration & Plasticity, Neuropathology
USE OF TRANEXAMIC ACID IN GUNSHOT WOUNDS TO THE HEAD
MD Ali Mansour1, MD Andrea Loggini2, MD Faten El Ammar1, MD, MBA Susan Rowell1, MD Victoria Marquevich3,
1University Of Chicago, Chicago IL, United States, 2Southern Illinois Healthcare, Carbondale IL, USA, 3Santo Domingo, Santo Domingo, Dominican Republic
Keywords: Drug Delivery, Ballistic Injury, Neurocritical Care
ENTROPY OF INTRACRANIAL PRESSURE
Eng Fernando Pose2,3, MD Nicolas Ciarrocchi5, MD Christos Lazaridis1,
1University Of Chicago, Chicago IL, United States, 2CONICET, Buenos Aires, Argentina, 3Instituto de Medicina Translacional e Ingenierıa Biomedica, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina, 4Universidad Nacional de Quilmes, Departamento de Ciencia y Tecnologıa, Bernal, Argentina, 5Hospital Italiano de Buenos Aires, Critical Care Medicine Section, Buenos Aires, Argentina
Keywords: Computational/Modeling, Biomechanics, Intracranial Pressure, Neurocritical Care
METHAMPHETAMINE USE AND TRAUMATIC BRAIN INJURY OUTCOMES: A SINGLE‐CENTER RETROSPECTIVE REVIEW
1Barrow Neurological Institute, Phoenix AZ, United States
Keywords: Neuroprotection, Hemorrhage, Neurocritical Care
HDAC INHIBITOR ROMIDEPSIN REDUCES NEUROINFLAMMATION AND ATTENUATES NEUROLOGICAL DEFICITS FOLLOWING TBI
1University of Maryland Baltimore School of Medicine, Baltimore MD, United States
Traumatic brain injury (TBI) triggers delayed molecular and cellular responses, including neuroinflammation, that contribute to neuronal loss and neurological dysfunction. TBI‐induced epigenetic changes may promote excessive inflammation and neurodegeneration. For example, activation of histone deacetylases (HDACs) may alter microglia transcriptomic signatures that promote pro‐inflammatory, neurotoxic phenotypes. Conversely, HDAC inhibitor (HDACi)‐induced changes in the chromatin at key promoter regions may favor gene expression that facilitates neurorestorative microglia phenotypes. Romidepsin (RMD) is a potent, class 1/2 HDACi that increases histone acetylation and improves cognitive outcome in experimental autism models. The current study evaluated effects of RMD on neuroinflammation and selected functional outcomes following experimental TBI. 12 week old C57Bl/6 mice received 3 daily injections of RMD or vehicle beginning immediately after or 5 weeks following a moderate, controlled cortical impact (CCI). Beamwalk, Y maze and Novel Object Recognition were used to assess neurological function. Animals were sacrificed at either 7 or 56 days after injury; the hippocampus and cortex were examined for protein and gene expression analyses and another set were taken for lesion volume analysis. RMD treatment not affect the motor dysfunction but significantly improved cognitive performance on the novel object recognition task both during the chronic and acute phases of TBI. RMD also attenuated TBI‐induced expression of the pro‐inflammatory genes CD68 and NOX2 in the hippocampus. These findings show that RMD has selective effects on cognitive function after TBI, which may in part reflect modulation of microglia activation. Thus, RMD may be a promising therapeutic intervention for brain injury.
Keywords: Behavioral Function, Cognition/Learning/Memory, Neurodegeneration, Inflammation/Immune Function, Neuropathology
INHIBITION OF VASCULAR REMODELING BY EPHA4 IN THE ACUTE PHASE OF ISCHEMIC STROKE
1Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg VA, United States, 2School of Neuroscience, Virginia Tech, Blacksburg VA, United States, 3Department of Chemistry, Virginia Tech, Blacksburg VA, United States
Ischemic stroke is a leading cause of death and long‐term disability in the United States. Pial collateral vessels – vascular redundancies that form during development and can allow for retrograde perfusion following ischemic stroke – are a major determinant of patient outcome and have therefore garnered attention as a therapeutic target. Our novel pre‐clinical murine findings suggest the receptor tyrosine kinase, EphA4, plays a role in hindering pial collateral growth and remodeling following surgically induced ischemic stroke (permanent middle cerebral artery occlusion, pMCAO). Utilizing conditional endothelial cell (EC)‐specific EphA4 knockout (EphA4fl/fl/Cdh5::CreERT2; KO) and wild type (EphA4fl/fl; WT) mice, we found that KO mice exhibited a significant reduction in infarct volume (24.0 ± 1.8mm3 vs 14.3 ± 2.5mm3; n = 9). This decrease in tissue damage correlated with larger ipsilateral pial collateral vessels as early as 4.5hrs (27.31 ± 0.6um vs 32.41 ± 0.8um; n = 15) and up to 24hrs post‐pMCAO (31.14 ± 0.8um vs 36.7 ± 0.9um; n = 15). Analysis of mRNA expression in the pial surface 24‐hours post‐pMCAO revealed a reduction in the expression of angiopoietin‐2 (1.4 ± 0.2 vs 0.8 ± 0.09; n = 5) and Tie1 (5.3 ± 1.8 vs 0.9 ± 0.2; n = 5), inhibitors of EC Tie2 signaling, in WT compared to KO tissue. To assess the role of Tie2 signaling in collateral growth, WT mice were treated with Vasculotide, an Angiopoeitin‐1 mimetic peptide. Vasculotide treatment resulted in significantly larger ipsilateral collateral vessels (30.45 ± 0.67um vs 36.60 ± 0.75um; n = 6), coupled with a significant decrease in infarct volume (18.6 ± 1.4mm3 vs 8.5 ± 0.6mm3; n = 4). Therefore, inhibiting EphA4 or stimulating Tie2 may represent novel options for therapeutically stimulating pial collateral vessel growth following ischemic stroke.
Keywords: Neuroprotection, Hypoxia/Ischemia, Vascular, Cerebral Blood Flow
FIGHTING FOR RECOVERY ON MULTIPLE FRONTS: SPINAL CORD INJURY CLINICAL TRIALS, PAST, PRESENT, AND FUTURE
1Texas A&M University, College Station TX, United States
Through decades of preclinical research, great progress in understanding the complex nature of spinal cord injury (SCI) has been achieved. However, although research efforts focused on developing novel effective therapies to improve the quality of life for individuals living with SCI are continually evolving, currently there remains no conclusive cure for SCI. Preclinical discoveries have significantly informed the development of clinical trials. Currently, over 1,400 clinical trials focused on promoting recovery after SCI are registered in the U.S. National Library of Medicine. With so many clinical trails, it is important to wholistically look and critically analyze the trends in parameters such as: phase of clinical trial, number of participants, type of intervention, primary outcome, and secondary outcome etc. By removing clinical trials that were listed as withdrawn or ineligible status, we categorized over 1,300 trials by type of intervention, primary outcome and secondary outcome. This review will demonstrate the change over time from the 1980's to current day in therapeutic interventions and highlight important shifts in focus of primary/secondary outcomes. Here, we review lessons learned from past trials and look toward the future as we continue fighting for recovery on all fronts from the lab bench to the clinic.
Keywords: Therapeutics/Drug Discovery
L‐SELECTIN SHEDDING REDUCES NEUTROPHIL ACCUMULATION AND IMPROVES LONG‐TERM RECOVERY AFTER SPINAL CORD INJURY
1Texas A&M University, College Station TX, United States
Spinal cord injury (SCI) is a traumatic event that can result in paralysis due to the disruption of neural circuitry. Neutrophils can cause further tissue damage after SCI, however, the mechanisms underlying pathogenic neutrophils activities in the injured spinal cord remain poorly understood. L‐selectin is an adhesion receptor that participates in trans‐endothelial migration of neutrophils from vasculature into inflamed tissue. L‐selectin contains a membrane‐proximal cleavage site and can undergo “shedding” or loss of the ligand‐binding ectodomain. We have previously shown that inducing L‐selectin shedding using FDA‐approved diclofenac improves functional recovery and white matter sparing after SCI. However, the effect of L‐selectin shedding on neutrophil accumulation and function after SCI remains unknown. To investigate the role of L‐selectin shedding in neutrophil function after SCI, we performed a thoracic contusion SCI in WT and L(E) mice (which express a non‐cleavable version of L‐selectin) and performed immunofluorescent staining on tissue sections at 3 days post‐SCI. To assess neutrophil accumulation, we quantified the total area of Ly6G staining and the number of Ly6G+ cells in tissue sections spanning the lesion site. In both methods, we observed a greater number of neutrophils in the injured spinal cord in L(E) mice compared to the WTs. Our previous data demonstrated no differences in neutrophils between WT and L(E) mice at 1 day post‐SCI, a time when neutrophil accumulation peaks. Our data suggests that the shedding of L‐selectin may play an essential role in prolonging neutrophil accumulation at the injury site.
Keywords: Secondary Injury, Inflammation/Immune Function
THE ROLE OF PRIOR TRAUMATIC BRAIN INJURY IN CURRENT INJURY OUTCOME
1National Institute of Neurological Disorders and Stroke, NIH, Bethesda MD, United States
Keywords: Behavioral Function, Secondary Injury, Concussion/mTBI
CHARACTERIZATION OF IMMUNE CELL INFILTRATION FOLLOWING MODERATE TRAUMATIC BRAIN INJURY IN MICE
Dr. Venkatramana Krishna1, Dr. Andrew Crane3, Nicole Emmitt1, Michael Patterson4, Dr. Walter Low2, Dr. Andrew Grande2, Dr. Jesse Williams4,
1Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul MN, United States, 2Department of Neurosurgery, University of Minnesota Medical School, Minneapolis MN, United States, 3Department of Pediatrics, University of Minnesota Medical School, Minneapolis MN, United States, 4Department of Integrative Biology & Physiology, University of Minnesota Medical School, Minneapolis MN, United States
Neuroinflammation is an important secondary injury mechanism that initiates and potentiates neuropathology following traumatic brain injury (TBI). CNS infiltration by peripheral immune cells after TBI has been observed in both preclinical and clinical studies. The objective of this study is to characterize the kinetics and inflammatory state of immune cell infiltration into the brain following TBI. Moderate TBI was induced by a controlled cortical impact (CCI) on the intact dura matter in 8‐week‐old female C57/BL6 mice and immune cell phenotypes in the brain were characterized by flow cytometry. To determine the contribution of resident versus infiltrating myeloid cells in neuroinflammation following TBI, CCR2+ circulating monocytes and resident CX3CR1+ microglia were identified using CCR2creER R26‐tdTomato x CX3CR1gfp reporter mice. To determine the source of infiltrating immune cells, bone marrow chimeras were generated by transplanting bone marrow from CD45.2 mice to radiation‐induced myeloablated CD45.1 congenic mice with heads protected to prevent CNS radiation. Neutrophils and CD45hi CD11b+ monocyte/ macrophages infiltration peaked at 1 and 3 days post‐injury (dpi), respectively. Fate mapping showed the presence of tdTomato+ Ly6C+ cells at 3 dpi, indicating infiltrating monocytes/macrophages. However, Ly6C+ cells and neutrophils in the brain of bone marrow chimeric mice were host‐derived and not from the donor bone marrow. In contrast, >80% of Ly6C+ monocytes and neutrophils in the blood and bone marrow of chimeric mice were donor‐derived. These results suggest that following TBI, infiltrating monocytes and neutrophils in the brain are not derived from circulation or peripheral bone marrow.
Keywords: Secondary Injury, Microglia, Inflammation/Immune Function
TRACKING NANOPARTICLE TREATMENT EFFECTS USING MAGNETIC RESONANCE IMAGING IN A CONTROLLED CORTICAL IMPACT MOUSE MODEL
1University Of Nebraska‐Lincoln, Lincoln NE, United States
Our project goal is to develop a minimally invasive process for tracking the treatment effects of multifunctional antioxidant nanoparticles (NPs) used to treat traumatic brain injury (TBI). To date, there is a limited understanding of the brain's microenvironment as it relates to NP intervention in TBI. We hypothesized that NPs would produce a detectable change in the microenvironment of injury sites over prolonged treatment and examination. We addressed our hypothesis by characterizing a series of NPs that are capable of sequestering reactive oxygenated species and lipid peroxidation products by testing their efficacy using a controlled cortical impact (CCI) mouse model via magnetic resonance imaging (MRI). To establish a treatment window, we used dynamic contrast‐enhanced MRI (DCE‐MRI) to compare NP accumulation and retention when administered at 0hr, 1hr, 3hr, 6hr, 24hr post‐injury (n = 3/ timepoint). We found that NPs injected 0hr post‐injury yielded greatest permeability around the injury site (p < 0.05). Microstructure and diffusivity changes were evaluated using diffusion tensor imaging (DTI, n = 3 for NP and untreated CCI mice) at 1 day, 3 day, 1 week, and 1 month post‐injury. Results demonstrated a difference in injury site mean diffusivity at 1‐month post‐injury (p < 0.05) suggesting cortical tissue protection. Brain metabolite tracking was conducted in these same mice using proton magnetic resonance spectroscopy (MRS). A decrease in N‐acetylaspartate and glutamate were recorded for CCI and NP treatment. In conclusion, we have found these MRI‐based methods are a useful tool for following the effects of NPs on TBI progression.
Keywords: Secondary Injury, Blood Brain Barrier, Imaging, Monitoring
REPLACING POLYDIMETHYLSILOXANE ENABLES LONG TERM EXPERIMENTS IN A HUMAN IN VITRO NEUROTRAUMA MODEL
1University Of Illinois At Chicago, Chicago IL, United States, 2Northwestern University Feinberg School of Medicine, Evanston, United States, 3Biomer Technology Limited, Warrington, United Kingdom
Most current 2D models of neurotrauma culture cells or tissues slices on sheets of polydimethylsiloxane (PDMS) that are stretched to induce trauma. PDMS has been used in neurotrauma modeling and other fields of cell biomechanics for decades because it is transparent, elastic and easy to manufacture. However, PDMS also has limitations. It is difficult to cure completely and uncured polymer leaches into the culture media and poisons cultures over time. Also, PDMS absorbs small molecules in an unpredictable fashion that distorts drug concentrations and complicates drug testing. Here, we address these issues by replacing PDMS with either FlexDym (a material marketed as a substitute for PDMS) or a highly biocompatible form of polyurethane. New manufacturing techniques were developed to incorporate these alternative membranes into an established in vitro neurotrauma model. Time lapse microscopy showed that fragile monocultures of human induced pluripotent stem cell‐derived neurons (hiPSCNs) survived longer on the alternative membranes than on PDMS. High speed videography of stretch experiments post‐processed with digital image correlation showed that dynamic stretch can be induced in the alternative membranes by indentation. Therefore, replacing PDMS may enable long term studies of post‐traumatic neurodegeneration in hiPSCNs without the need for glial support cells. hiPSCNs are an attractive system for studying post‐traumatic neurodegeneration because they excel at modeling genetic variation across human subjects that may influence this pathology.
Keywords: Stem Cells, Biomaterials, Biomechanics
GENETIC ABLATION OF SARM1 REDUCES TAU HYPERPHOSPHORYLATION AFTER TRAUMATIC BRAIN INJURY IN MICE
1University of Massachusetts, Chan Medical School, Worcester MA, United States
Keywords: Neurodegeneration, Axonal Injury, Concussion/mTBI, Chronic Traumatic Encephalopathy, Neuropathology
TRAUMATIC BRAIN INJURY PROMOTES LONG‐TERM NEUROLOGICAL DEFICITS AND NEURODEGENERATION IN TRANSGENIC MICE EXPRESSING HUMAN C9ORF72 HEXANUCLEOTIDE REPEAT EXPANSIONS
1Department of Neurology, University of Massachusetts, Chan Medical School, Worcester MA, United States, 2Department of Psychological and Brain Sciences, University of Massachusetts, Amherst MA, United States, 3Department of Pathology, University of Massachusetts, Chan Medical School, Worcester MA, United States
Keywords: Neurodegeneration, Gene Expression, Cell Death
ESTABLISHING HEALTHY PORCINE GAIT REFERENCE RANGES TO TRACK GAIT ALTERATIONS AFTER TRAUMATIC BRAIN INJURY
1Department Of Biomedical Engineering, Georgia Tech And Emory University, Atlanta GA, United States, 2Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio TX, United States
Mild traumatic brain injury (mTBI) represents >80% of pediatric TBIs, and functional disabilities, like motor impairments, can persist even after other symptoms have resolved. The pig is a well‐developed animal model for TBI and other diseases, and we sought to identify reliable, objective gait metrics and establish healthy normal ranges to track alterations following TBI. Male and female 4‐week old Yorkshire swine were acclimated to a Tekscan Strideway™ pressure system for three days, then assessed in healthy normals (N = 16), and before, and 1, 4 and 7 days after a single (N = 7) or multiple (N = 10) rapid nonimpact head rotations (RNR) or an anesthetized sham experience (N = 8). Reference ranges (RR) were calculated using the 2.5th and 97.5th percentile values of daily averages from a set of healthy animals tested on 3 nonconsecutive days (RR group, N = 10). Daily averages from separate animals (validation group, N = 6) tested 1‐3 days were calculated and compared to the RR; metrics with >80% values in the RR were considered reliable (velocity, gait time, cycle time, cycles per minute, stride length, stride time, stride velocity, stance time, and swing time). Using Fisher's Exact Test, Cochran Q Test, and McNemar's test, these reliable metrics for single, multiple and shams were compared to the RR. Multiple RNR animals fell significantly below the RR for stride length and stride velocity. We have established reliable immature porcine gait metrics and developed healthy RR that can be used to identify alterations after TBI. Funded by the Georgia Research Alliance and NIH R01NS097549.
Keywords: Pediatric, Behavioral Function, Concussion/mTBI, Biomechanics
THE EFFECT OF SELF‐REPORTED LEVEL OF SLEEP DISTURBANCE ON SYMPTOM SEVERITY IN PEDIATRIC CONCUSSION
1Arnold School of Public Health, University of South Carolina, Columbia SC, United States, 2Department of Pediatrics, Prisma Health Children's Hospital, Columbia SC, United States
Sleep disturbances are a common occurrence in adolescents after concussion. However, little research has systematically examined the influence of sleep disturbance using both subjective and objective measures of functioning. The aim of this study was to examine the influence of self‐reported levels of sleep disturbance on concussion outcomes by comparing adolescents reporting low (lowSD, n = 30) and high sleep disturbance (HighSD, n = 30) on the NIH Neuro‐QoL Sleep form. Patients were matched on key demographic factors. Cognitive function, heart rate variability, balance and vision, and symptom severity were measured at initial (T1) and follow‐up (T2) clinical evaluations. No group*time differences were found for balance, vision, cognition or heart rate variability. However, a significant decrease in heart rate variability was observed for HighSD compared to LowSD patients at both timepoints (p = .02). Similarly, HighSD patients also reported significantly worse dizziness, nausea & fogginess during Visual Ocular‐Motor Screening, and exhibited significant deficits in attention and working memory at both time points relative to LowSD patients (ps≤.04). Lastly, a significant group*time interaction was observed for Rivermead Post‐Concussion Symptom Questionnaire. Post hoc analyses revealed that HighSD patients had higher scores at T1 for all three subscales, Emotion, Cognition and Somatic (p < .001), and for Emotion and Cognition at T2 (p = .001, p < .001). These findings highlight the importance of sleep following concussion and the need to more effectively manage patients with sleep disturbance. Future research should seek to validate interventions to reduce sleep disturbance and optimize injury recovery.
Keywords: Pediatric, Sleep, Concussion/mTBI
THE EFFECT OF SELF‐REPORTED LEVELS OF SLEEP DISTURBANCE ON FUNCTIONAL OUTCOMES IN PEDIATRIC CONCUSSION
1Arnold School of Public Health, University Of South Carolina, Columbia SC, United States, 2Department of Pediatrics, Prisma Health Children's Hospital, Columbia SC, United States
Sleep disturbances are a common occurrence in adolescents after concussion. However, little research has systematically examined the influence of sleep disturbance using both subjective and objective measures of functioning. The aim of this study was to examine the influence of self‐reported levels of sleep disturbance on concussion outcomes by comparing adolescents reporting low (LowSD, n = 30) and high sleep disturbance (HighSD, n = 30) on the NIH Neuro‐QoL Sleep form. Patients were matched on key demographic factors. Cognitive function, heart rate variability, balance and vision, and symptom severity were measured at initial (T1) and follow‐up (T2) clinical evaluations. No group*time differences were found for balance, vision, cognition or heart rate variability. However, a significant decrease in heart rate variability was observed for HighSD compared to LowSD patients at both timepoints (p = .02). Similarly, HighSD patients also reported significantly worse dizziness, nausea & fogginess during Visual Ocular‐Motor Screening, and exhibited significant deficits in attention and working memory at both time points relative to LowSD patients (ps≤.04). Lastly, a significant group*time interaction was observed for Rivermead Post‐Concussion Symptom Questionnaire. Post‐hoc analyses revealed that HighSD patients had higher scores at T1 for all three subscales, Emotion, Cognition and Somatic (p < .001), and for Emotion and Cognition at T2 (p = .001, p < .001). These findings highlight the importance of sleep following concussion and the need to more effectively manage patients with sleep disturbance. Future research should seek to validate interventions to reduce sleep disturbance and optimize injury recovery.
Keywords: Pediatric, Sleep, Concussion/mTBI
NEURONAL ACTIVITY‐BASED THERAPIES DO NOT ENHANCE SYMPATHETIC AXONAL REGENERATION
1Emory University Medical Scientist Training Program, Atlanta GA, United States, 2Emory University Neuroscience Graduate Program, Atlanta GA, United States, 3Emory University Department of Cell Biology, Atlanta GA, United States
Axonal injuries are common and lead to a loss of motor, sensory, and autonomic functions that lead to lifelong disabilities. Enhancing axon regeneration is important for the development of novel therapeutics to complement surgical repair, such as nerve transfers for hand reanimations after spinal cord injury. However, the regenerative capacity of post‐ganglionic sympathetic axons and their functional recovery has rarely been studied. Sympathetic innervation plays a major role in muscle strength and thermoregulation. The objective of this study is to study the regenerative capacity of sympathetic axons in the sciatic nerve after injury following neuronal activity‐based treatments.
Keywords: Axonal Injury, Synaptic Function, Exercise, Electrophysiology, Regeneration & Plasticity, Metabolism/Energetics, Neurogenesis
IMPACT OF SOCIAL MEDIA IN PROMOTING AWARENESS OF THE FENCING RESPONSE AND TRAUMATIC BRAIN INJURY
Dr. Kyle L Roe1, Katherine R Giordano1,2, Dr. Gary A Ezzell1,
1University of Arizona, Phoenix AZ, United States, 2Phoenix VA Health Care System, Phoenix AZ, United States, 3Phoenix Children's Hospital, Phoenix AZ, United States
In 2009, the fencing response described an overt visual indication of traumatic brain injury (TBI) based on video observation in individuals subjected to brain injury forces of moderate magnitude. Upon impact to the head, the fencing response is the extension and/or flexion of arms and tonic posturing for several seconds. Educating the general public about the fencing response promotes brain injury awareness and detection of possible TBIs. Our objective was to demonstrate increased public awareness of the fencing response using Twitter and Wikipedia data.
Raw data were accessed using RStudio packages “academictwitteR”, “wikipediatrend” and “pageviews”. Tweets with “fencing response” text and Wikipedia page views were queried (2010‐2019). Data were clustered by weekday, month, half‐year, and year to identify trends.
Tweets that mentioned the fencing response increased annually from 2010 to 2019. Most Tweets occurred on Sunday, followed by Monday. More than three times as many Tweets mentioned the fencing response during the months of September‐February compared to March‐August (American football season). Wikipedia article views increased annually from 2010 to 2019. Monthly views varied, with the most in January. Views by weekday varied with no clear pattern.
Twitter mentions and Wikipedia views of the fencing response increased over time following peer‐reviewed publication. Use of social media has increased public awareness of the fencing response and demonstrates the impact of effective science communication. Greater awareness of the fencing response as a “red‐flag” sign of TBI among coaches, athletic trainers, and sports fans has the potential to guide decisions regarding medical care.
Keywords: Biomarker, Concussion/mTBI, Diagnostics, Consciousness
EFFECTS OF ACUTE ETHANOL INTOXICATION ON SPINAL CORD INJURY OUTCOMES
1Spinal Cord and Brain Injury Research Center, University Of Kentucky, Lexington KY, USA, 2Department of Physiology, University Of Kentucky, Lexington KY, USA, 3Department of Psychology, University Of Kentucky, Lexington KY, USA, 4University of Kentucky MD/PhD Program, Lexington KY, USA
Approximately, one in three traumatic spinal cord injuries (SCI) occurs during or shortly after the consumption of alcohol. Retrospective clinical studies report variable effects of alcohol intoxication on mortality, neurological recovery, and complications after SCI. Some studies suggest there is a protective effect of alcohol intoxication on SCI outcomes while others suggest it causes an increased complication risk. Preclinical studies in rodent and feline SCI models have employed a supraclinical BAC and demonstrated a detrimental effect on neurological recovery and hemorrhage. Therefore, we combined pre‐clinical rodent models of acute ethanol intoxication and experimental T9 contusion SCI to simulate this scenario in female mice. We first investigated the effect of SCI on ethanol metabolism and found that SCI does alter the rate of ethanol catabolism. However, we did find that isoflurane anesthesia significantly slowed ethanol metabolism independent of SCI. We also determined how acute ethanol intoxication at the time of SCI alters locomotor recovery and lesion pathology. Using the Basso Mouse Scale (BMS) and CatWalk XT gait analysis system, we assessed locomotor recovery for six weeks after injury and observed that acute ethanol intoxication at the time of injury did not alter locomotor recovery. Similarly, there was no effect of ethanol intoxication on tissue sparing after SCI. Therefore, we conclude that acute alcohol intoxication at the time of injury may not alter neurological recovery in a rodent model of SCI and may not contribute to tissue pathology.
This work was funded by the NIAAA training grant T32 AA027488
Keywords: Neuroprotection, Behavioral Function, Secondary Injury, Neurodegeneration
CLINICAL RISK FACTORS ASSOCIATED WITH CEREBROSPINAL FLUID LEAK IN FACIAL TRAUMA: A RETROSPECTIVE ANALYSIS
1University of Florida, Gainesville GA, United States
Keywords: Secondary Injury, Cerebrospinal Fluid, Imaging, Biomechanics
PUPILLARY LIGHT RESPONSES ARE SIGNIFICANTLY DEPRESSED AFTER SINGLE AND MULTIPLE SAGITTAL HEAD ROTATIONS IN PIGLETS
Giancarlo Riccobono2, Ms. Mackenzie Mull1, Dr. Anna Oeur1,
1Emory University, Atlanta GA, United States, 2Georgia Institute of Technology , Atlanta GA, United States
Problems with visual processing are a common symptom of concussion and pupillary light responses (PLR) provide an assessment of the visual pathways that could be affected after injury. Employing 4‐week‐old piglets and a rapid non‐impact head rotation (RNR) model for traumatic brain injury, we studied PLR in healthy (n = 7), anesthetized sham (n = 5), single RNR (n = 5), and multiple RNR (n = 6). A PLR device was used to assess the healthy group (3 test days) to establish healthy reference ranges (RR). For sham, single (100 rad/s) and multiple RNR (100 rad/s, 60 rad/s x 4 within 1 hour) measurements were taken before, at day 1, 4 and 7 post injury. A repeated measures MANOVA was conducted on the average response of both eyes. An interaction effect (day x group) was significant for initial and end pupil diameters (p < 0.05), including post hoc analyses that showed significant decreases in multiple compared to pre‐injury and remained significantly lower at day 7 in comparison to pre‐injury (p < 0.05). There was a main effect of day on average pupil constriction velocity (p = 0.038) and post hoc analyses revealed that this measure was sensitive to changes in the single RNR group where velocity was depressed at day 1 and 4 post injury (p < 0.05). On day 4, single RNR had lower velocities than sham and multiple groups (p < 0.05). Healthy RR were established for each measure and comparisons were completed to determine which group of animals fell within RR on each day. Supported by NIH R01NS097549 and the Georgia Research Alliance.
Keywords: Concussion/mTBI
VISUAL EVENT RELATED POTENTIALS ARE ALTERED AFTER MULTIPLE SAGITTAL ROTATIONS IN PIGLETS
1Emory University, Atlanta GA, United States, 2Georgia Institute of Technology , Atlanta GA, United States
Visual deficits are a symptom of concussion and visual evoked potentials (VEPs) can track neural integrative processing. The porcine rapid non‐impact head rotation (RNR) is a model of traumatic brain injury (TBI). We studied VEPs in shams (N = 5) and before and 1, 4, and 7 days after multiple RNR applied within 1 hour in 4‐week‐old female piglets (N = 7, 100 rad/s + four 60 rad/s). A white light stimulus was presented to the left eye 30 times per trial, 6 trials/day using a 32‐electrode net. VEPs were modelled using a piglet FE and current density associated with visual processing were localized in 5 brain regions at 50, 85, and 110 ms post‐stimuli to capture the progression of neural processing around maximum cortical activity. A 3‐way repeated measures ANOVA (region, day, and injury group) revealed a main effect of region at 50 and 85ms, interaction effects at 85 ms (day x injury group) and 110 ms (day x injury group x brain region; p < 0.05). Post hoc analyses showed that the right temporal and occipital regions had greater current densities at 50ms compared to the other regions. At day 4, current densities (85 ms) were greatly reduced in multiple RNR (p < 0.001) which was not observed at day 7. Current densities (110 ms) on day 4 were reduced for multiple RNR in the temporal region where at pre‐injury this group had greater activations (p < 0.05). VEP current densities are significantly depressed by day 4 after multiple RNR. Supported by NIHR01NS097549 and Georgia Research Alliance.
Keywords: Pediatric, Behavioral Function, Concussion/mTBI
INTEGRATING BIOMECHANICS WITH STAKEHOLDER PERSPECTIVES TO INFORM HEAD IMPACT SAFETY IN YOUTH FOOTBALL
1Department of Biomedical Engineering, Winston Salem NC, United States, 2Department of Implementation Science, Winston Salem NC, United States, 3Department of Public Health Sciences ‐ Social Sciences, Winston Salem NC, United States, 4Department of Family and Community Medicine, Winston Salem NC, United States, 5Department of Gerontology and Geriatric Medicine, Winston Salem NC, United States
In response to rising concerns for brain health, youth football organizations have implemented regulations to reduce contact and concussion risk; however, evidence to effectively inform policies is lacking. The objective of this study is to integrate biomechanical, survey, and qualitative data to inform the development of an evidence‐based intervention to reduce head impact exposure in youth football practices. Football players (n = 31) participating on two middle school level teams (ages 11‐13) were fitted with mouthpiece‐based head acceleration sensors (recording threshold: 5g); 5,648 verified head acceleration events were collected. The median [95th percentile] linear and angular acceleration was 9.6 g [29.3 g] and 677 rad/s2 [2166 rad/s2], respectively. Parents (n = 13) and coaches (n = 10) of each team participated in separate, team‐specific monthly focus groups where biomechanical data were shared with participants and receptivity to changes to football practice that could reduce head impact exposure was assessed. We also measured the acceptability and feasibility of changing practice using a validated instrument (5‐point scale). Overall, coaches reported creating safer practices as acceptable (4.95) and feasible (4.70). Parents were supportive, but less so than coaches (4.57 and 4.32, respectively). Preliminary focus group findings revealed that parents and coaches felt that use of proper technique and mental focus were important for injury prevention. Benefits of participating in youth football were discussed, while many stakeholders identified athlete safety concerns. Overall, stakeholders found value in using biomechanics data to inform head impact safety in football but recognized challenges in developing and implementing strategies at the youth level.
Keywords: Pediatric, Concussion/mTBI, Biomechanics
CYCLOOXYGENASE AND EP3 RECEPTOR INHIBITION FOLLOWING REPEATED BLAST‐INDUCED TRAUMATIC BRAIN INJURY IN RAT ORGANOTYPIC HIPPOCAMPAL SLICE CULTURES AMELIORATES LONG TERM POTENTIATION DEFICITS
1Columbia University, New York NY, United States
Repeated blast induced traumatic brain injury (bTBI) in rat organotypic hippocampal slice cultures (OHSC) impaired long term potentiation (LTP). OHSCs were exposed to repeated level 1, 2, or 3 blasts with varying inter‐blast intervals (IBI, 1 day, 3 day or 6 day); LTP was measured after a 4 day recovery period. Following two Level 3 blasts delivered one or three days apart, there was significant LTP deficits. A subset of OHSCs were exposed to two repeated level 3 blasts with a 1 day IBI and treated with ibuprofen (50 μM, 200 μM, 400 μM, and 1000 μM), rofecoxib (2.5 nM, 25 nM, and 50 nM), SC‐560 (10 nM, 20 nM, and 200 nM), or L‐798,106 (100 nM, 250 nM, 1000 nM, and 2000 nM). Treatment with ibuprofen (200 or 400 μM), a non‐specific cyclooxygenase inhibitor, after repeated bTBI significantly attenuated LTP deficits. Treatment with the cyclooxygenase ‐2 specific inhibitor, rofecoxib (25nM), and the cyclooxygenase ‐1 specific inhibitor, SC‐560 (20nM), also significantly attenuated LTP deficits following repeated bTBI. Lastly, all concentrations above 100nM of L‐798,106, an EP3 receptor inhibitor, reduced injury induced LTP deficits. Our findings suggest that inhibiting cyclooxygenase or EP3 receptors after repeated bTBI contributes to the recovery of LTP. This research was supported by the Army Research Laboratory.
Keywords: Blast, Therapeutics/Drug Discovery, Electrophysiology, Regeneration & Plasticity
A PUBLICLY AVAILABLE DATASET OF HUMAN BRAIN BIOMECHANICS USING MR IMAGING FOR COMPUTATIONAL MODEL VALIDATION
1Johns Hopkins University, Baltimore MD, United States, 2Washington University in St. Louis, St. Louis MO, United States, 3The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda MD, United States, 4National Institutes of Health, Bethesda MD, United States, 5University of Delaware, Newark DE, United States
Traumatic brain injury (TBI) results from tissue deformation in response to rapid head motions. Computational models for TBI simulation provide insight into the mechanisms of injury and can help develop safety countermeasures. However, models require both accurate inputs (geometry, boundary conditions, and material parameters) and experimental measurements of brain deformation for validation. While measurements of brain deformation have been made in cadaveric specimens, publicly available data on the biomechanics of the in‐vivo human brain is needed for robust model development and validation.
We are collecting three types of data for developing and validating computational models: 1) Anatomical magnetic resonance (MR) imaging data, comprised of T1‐w, T2‐w, susceptibility weighted imaging (SWI), time of flight MR angiography (MRA‐ToF), and diffusion tensor images, which are processed to label the brain and other structures, including axonal tracts, falx, tentorium, vasculature, and meninges; 2) Multi‐frequency MR elastography is used to characterize the linear viscoelastic material properties of the brain at harmonic loading, resulting in voxel‐wise measurements of brain displacement, strain, and material properties; 3) Tagged MR imaging is used to measure how the brain deforms in response to mild deceleration loading during neck extension and neck rotation, resulting in 3D dynamic displacement and strain fields over time.
The data are collected at three acquisition sites with centralized processing and quality assessment, and are being made publicly available (
Keywords: Imaging, Concussion/mTBI, Computational/Modeling, Biomechanics
INVESTIGATING THE BIOMECHANICS OF THE BRAIN‐SKULL INTERFACE USING SUBJECT‐SPECIFIC COMPUTATIONAL BRAIN MODELS
1Johns Hopkins University, Baltimore MD, USA, 2The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda MD, USA, 3Washington University in St. Louis, St. Louis MO, USA, 4University of Delaware, Newark DE, USA
Finite element (FE) models of the human brain are the state‐of‐the‐art technique for simulating real‐world head impacts to assess brain injury risk. Subject‐specific brain models minimize model assumptions in the simulated brain deformation. An unknown in many models is how to represent the connection between the brain and skull, and what data can validate the brain‐skull interface response. Previous models have used various material representations of the subarachnoid space (SAS), with inconclusive results because of limited, sparse brain motion data.
We developed a subject‐specific brain FE model of a 31‐year‐old male that includes neuroanatomy from magnetic resonance (MR) images, material properties from MR elastography, and brain deformation measurements using tagged MR experiments under mild head rotation. To investigate the choice of SAS material, nine models were simulated and relative brain‐skull displacement/strain at cortical brain regions were compared to the experimental measurements from tagged MR. All SAS models used a tied node interface between all elements.
There were significant differences between simulations and experimental data in maximal strain (0.025‐0.08 mm/mm) and displacement (0.38‐1.8 mm) at cortical brain elements, with soft viscoelastic materials outperforming all models. The choice of SAS material affects both the peak strain magnitude and temporal dynamics of brain motion. Features of the experimental data that none of the SAS models matched included asymmetric strain distributions, relative sliding, and a highly damped response at the brain skull interface. Future work will focus on assessing new material implementations of the SAS, including cohesive zone modeling and computational fluid methods.
Keywords: Cerebrospinal Fluid, Imaging, Concussion/mTBI, Computational/Modeling, Biomechanics
COMPARING THE THERAPEUTIC AND TREATMENT WINDOWS OF ANTIOXIDANT NANOPARTICLES BETWEEN MALE AND FEMALE MOUSE MODEL OF TBI
1University Of Nebraska‐Lincoln, Lincoln NE, United States, 2Missouri University of Science and Technology, Rolla MO, United States
Reactive oxygen species (ROS) and lipid peroxidation products (LPOx) are major contributors to the progression of secondary injury of TBI. Currently, antioxidant therapies are limited to an 8 h treatment window following injury, whereas LPOx therapies extend this window to 24 h post‐injury. To expand the treatment window, we have developed nanoparticles (LIPOMA) with a size of 9 nm and scavenge around 0.3 μmol ROS and 0.07 μmol LPOx per mg LIPOMA. Using the controlled cortical impact (CCI) mouse model of TBI, we identified the treatment and therapeutic windows of LIPOMA as well as the effects on post‐traumatic oxidative stress and necrosis in both male and female mice (8‐weeks‐old; n = 3 for all treatment groups). Through Ktrans imaging using DCE‐MRI, we observed the highest accumulation of LIPOMA when injected 0 h post‐CCI, with accumulation still observed when injected 24 h post‐CCI, in both male and female mice. Using dihydroethidium at 4 h post‐CCI, we found the maximal inhibition window of post‐traumatic oxidative stress with LIPOMA between 4‐20 mg/kg in male (p < 0.05) and 4‐40 mg/kg in female mice (p < 0.01) when injected 0 h post‐CCI. LIPOMA (8 mg/kg, 0 h post‐CCI) decreased post‐traumatic necrosis in the ipsilateral cortex at 3 d post‐CCI, as determined by Western blot of 150 kDa α‐II‐spectrin breakdown products, by 30% in male (p < 0.05) and 33% in female (p < 0.05) mice. Thus, our results suggest that LIPOMA is a promising candidate to reduce post‐traumatic oxidative stress and necrosis in both males and females.
Keywords: Neuroprotection, Secondary Injury, Biomaterials, Therapeutics/Drug Discovery
EXPOSURE TO LOW‐INTENSITY BLAST INCREASES CLEARANCE OF BRAIN Aβ
1Henry M Jackson Foundation, Silver Spring MD, United States, 2Parsons Corp, 3James J. Peters Department of Veterans Affairs, Bronx NY, USA, 4University of Virginia, Charlottesville VA, USA , 5Naval Medical Research Center, Silver Spring MD, USA
The long‐term effects of exposure to blast overpressure are an important health concern in military personnel. Increase in amyloid beta (Aβ) has been documented after non‐blast TBI and may contribute to neuropathology and an increased risk for Alzheimer's Disease. We have shown that Aβ levels decrease in the acute phase following exposure to low‐intensity blast. To further explore this observation, we examined the effects of a single 37kPa blast exposure on brain Aβ levels, production and clearance mechanisms in the acute (24 hours) and delayed (28 days) phases post‐blast exposure in an experimental rat model. Aβ and, notably, the highly neurotoxic detergent‐soluble Aβ42 form, was reduced acutely after blast exposure. This reduction was not associated with changes in the levels of Aβ oligomers, expression levels of amyloid precursor protein (APP), or increase in enzymes involved in the amyloidogenic cleavage of APP, the β‐ and ϒ‐secretases BACE1 and presenilin‐1, respectively. The levels of ADAM17 α‐secretase (also known as tumor‐necrosis factor α (TNFα )‐converting enzyme) decreased , concomitant with the reduction in brain Aβ and TNFα. Additionally, significant increases in brain levels of the endothelial transporter, low‐density related protein 1 (LRP1), and enhancement in co‐localization of AQP4 to perivascular astrocytic end‐feet occurred acutely after blast. These findings suggest that exposure to low‐intensity blast may enhance clearance of Aβ by LRP1‐mediated transcytosis through the endothelium as well as AQP4‐aided glymphatic clearance. Collectively, the data demonstrate that low‐intensity blast alters enzymatic, transvascular, and perivascular clearance of Aβ and may modulate the inflammatory response.
Keywords: Astrocyte, Blast, Concussion/mTBI, Vascular
PROGESTERONE DECREASED LONG TERM POTENTIATION DEFICITS AFTER REPETITIVE MILD PRIMARY BLAST
1Columbia University Department Of Biomedical Engineering, New York NY, United States
There is growing concern that repeated exposure to shock waves of lower intensities than improvised explosive devices may contribute to neurocognitive deficits, particularly service members such as trainers who are subjected to repeated exposures. Our previous studies demonstrated significant decreases in long term potentiation (LTP) in organotypic hippocampal slice cultures (OHSC) 24 hours following rapidly successive mild blast exposure. In our current studies, we used progesterone to interrogate the injury mechanism. Blasts were generated with a 76‐mm diameter aluminum shock tube (190.5mm driver section and 1240 mm long driven section) to deliver a peak overpressure of 45.67 ± 8.74 kPa, duration of 2.77 ± 0.05 ms, and impulse of 53.40 ± 6.96 kPa*ms. The lower peak overpressure and longer shock wave duration better simulates lower intensity artillery. OHSCs were exposed to triple repeat blasts in rapid succession. At 24hr following injury, synaptic plasticity (LTP) was measured in the CA1. Death was less than 5% for all samples. Progesterone was added 1 hour following injury. All three concentrations (0.1nM, 1nM, and 10nM) led to higher LTP than the vehicle, with 1nM progesterone having the most potent protective effect. Treatment with both 1nM progesterone and 10nM RU486, a progesterone receptor antagonist, led to LTP deficits compared to progesterone alone, but increased LTP compared to vehicle. RU486 alone did not cause LTP deficits in uninjured slices. Together the findings support the hypothesis that progesterone is providing a neuroprotective effect via the progesterone receptor binding pathway.
Funded by Army Research Laboratory.
Keywords: Neuroprotection, Blast, Concussion/mTBI, Electrophysiology
THE DYNORPHIN/KAPPA OPIOID RECEPTOR MEDIATES ADVERSE BEHAVIORAL OUTCOMES INDUCED BY REPETITIVE BLAST MILD TRAUMATIC BRAIN INJURY
1Veteran Affairs Puget Sound Health Care System, Seattle WA, United States
Mild traumatic brain injury (mTBI) from repetitive blast exposure is highly comorbid with post‐traumatic stress disorder (PTSD), depression, and chronic pain, yet effective treatment options are limited. Trauma is associated with aversion/dysphoria, mediated largely by the endogenous dynorphin/kappa opioid receptor (KOR) system. Critically, trauma‐induced KOR activation can exacerbate affective disorders and the risk for substance abuse. However, the role KOR signaling plays in behavioral symptoms of people and animal models with a history of blast trauma is not well understood. We have reported that rodents exposed to repetitive blasts develop PTSD‐like behaviors that include chronic aversion/dysphoria to blast‐paired cues. Here, we hypothesized that the KOR system mediates blast‐induced aversion/dysphoria and evaluated this by pharmacologically antagonizing KOR. We utilized a pneumatic shock tube that delivers clinically relevant blast waves onto mice. Male mice were pretreated with vehicle (saline) or the selective long‐acting KOR antagonist norbinaltorphimine (norBNI) prior to repetitive (3x) sham (anesthesia only) or blast exposure, followed by behavioral testing after one month. KOR antagonism did not block blast‐induced increase in acute loss of righting reflex or weight loss. Conversely, KOR antagonist pretreatment prevented blast‐induced conditioned aversion, hyperarousal, and light sensitivity, but not sensorimotor deficits when tested one‐month post sham/blast exposure.
Our results suggest that norBNI inhibited blast‐induced affective but not sensorimotor deficits in blast exposed mice. Together, these data highlight a new potential therapeutic strategy targeting the KOR system to prevent chronic neuropsychological symptoms experienced by individuals with blast‐related mTBI. Funding by VA BLR&D 1IK2BX003258, VA Seed, MIRECC, and GRECC.
Keywords: Behavioral Function, Blast, Post‐Traumatic Stress, Concussion/mTBI
ACUTE, SEX‐SPECIFIC IMPAIRMENT OF THE MITOCHONDRIAL RESPIRATORY CHAIN IN A JUVENILE RAT MODEL OF TRAUMATIC BRAIN INJURY
1Department of Anesthesiology and Shock, Trauma, and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore MD, United States, 2Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore MD, United States
Mitochondrial bioenergetic impairment is thought to contribute to secondary brain damage following traumatic brain injury (TBI). However, isolating mitochondria of sufficient quality and yield to assess respiration ex vivo is an obstacle to evaluating electron transport chain (ETC) function post‐TBI. Using the 17 day‐old controlled cortical impact rat model of immature TBI, the objective of this study was to determine whether damage to the ETC occurs in the injured brain hemisphere of either males or females at 24 hours post‐TBI. We adapted Seahorse‐based Extracellular Flux respirometry (Agilent) to measure Complex I‐, II‐, and IV‐dependent oxygen consumption rates (OCR) using only four micrograms of frozen brain homogenates per measurement. Measurements were made from ipsilateral, injured hemispheres, compared to contralateral, control hemispheres from the same animals. The pore‐forming peptide alamethicin was used to supply NADH to the mitochondrial matrix and was added in combination with purified cytochrome c to allow for Complex III to Complex IV electron transfer in permeabilized mitochondria. The Complex I inhibitor rotenone, the Complex II substrate succinate, and the Complex IV substrate TMPD, in combination with the reducing agent ascorbate, were then successively added. No significant differences were observed between ipsilateral and contralateral rates of Complex I‐, II‐, or IV‐dependent oxygen consumption in females (n = 11). However, Complex I‐ and Complex IV‐dependent OCRs were significantly reduced in injured male brain relative to the contralateral side (Two‐way ANOVA, p < 0.05, n = 11). Future work will search for the mechanism underlying this unexpected sex difference and whether it relates to long‐term behavioral outcome.
Keywords: Pediatric, Secondary Injury, Metabolism/Energetics
COMBINING AUTOLOGOUS NEURAL STEM CELL TRANSPLANT WITH FIBRIN HYDROGEL AND RHO INHIBITOR RHO GTPASE INHIBITOR FOR THERAPY IN RHESUS MONKEY SPINAL CORD INJURY
1University of California Riverside, Riverside CA, United States, 2Royan Institute, Tehran, Iran
Keywords: Behavioral Function, Stem Cells, Biomaterials, Transplantation, Neurogenesis
UNIQUE FORM OF BLAST‐RELATED ASTROCYTIC DYSMORPHOLOGY IN POSTMORTEM BRAINS FROM MILITARY PERSONNEL SUGGESTS SIGNIFICANT ASTROCYTE DYSFUNCTION
1Department of Pathology, Uniformed Services University School of Medicine, Bethesda MD, USA, 2VA Medical Center (VAPSHCS) and University of Washington, Seattle WA, USA, 3M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda MD, USA, 4James J. Peters VA Medical Center and Icahn School of Medicine at Mount Sinai, New York NY, USA, 5State University of New York (SUNY), Albany NY, USA
Keywords: Astrocyte, Blast, Blood Brain Barrier, Neuropathology
HEAD KINEMATICS IN DIRT TRACK RACING: QUANTIFYING DIFFERENCES BETWEEN TRACKS
1Wake Forest School of Medicine Department of Biomedical Engineering, Winston‐Salem NC, United States, 2Virginia Tech ‐ Wake Forest University School of Biomedical Engineering and Sciences, Winston‐Salem NC, United States, 3Wake Forest School of Medicine Department of Neurosurgery, Winston‐Salem NC, United States, 4Wake Forest School of Medicine, Winston‐Salem NC, United States, 5Wake Forest School of Medicine Department of Orthopaedic Surgery & Rehabilitation, Winston‐Salem NC, United States, 6Atrium Health Wake Forest Baptist Medical Center Department of Neurology, Section of Neuropsychology, Winston‐Salem NC, United States, 7Wake Forest School of Medicine Department of Family and Community Medicine, Winston‐Salem NC, United States
The objective of this study was to compare head kinematics experienced by race car drivers during open‐wheel races across various dirt tracks throughout the United States. Instrumented mouthpiece sensors were used to collect head motion data from four drivers. During races, mouthpiece sensors measured tri‐axial linear acceleration and rotational velocity of the head at 200 Hz; rotational acceleration was derived from rotational velocity. Data associated with complete racing laps were identified via film review. A moving average was subtracted from head motion data of each lap to obtain head motion irrespective of periodic movement around the track. Deviations from the moving average (i.e., “perturbations”) were identified from linear acceleration and rotational velocity data. Peak magnitudes of laps and the magnitude and frequency of perturbations were compared between tracks. A total of 2,484 laps were segmented from 521 driver‐races at 26 unique tracks. The median peak linear acceleration (PLA), rotational acceleration (PRA), and rotational velocity (PRV) of all laps recorded at each track ranged from 4.65 g to 6.63 g, 145 rad/s2 to 239 rad/s2, and 2.54 rad/s to 3.51 rad/s, respectively. The median frequency of perturbations ranged from 4.00 Hz (angular perturbations about inferior‐superior axis) to 9.73 Hz (linear perturbations along inferior‐superior axis). The median peak‐to‐peak LA, RA, and RV of perturbations ranged from 1.37 g to 2.19 g, 53.8 rad/s2 to 82.8 rad/s2, and 0.65 rad/s to 1.15 rad/s, respectively. Understanding factors that influence differences in exposure between tracks may help inform safety interventions.
Keywords: Concussion/mTBI, Biomechanics
SEX‐DEPENDENT COGNITIVE DYSFUNCTION FOLLOWING REPEATED MILD TBI IN ADOLESCENT ANIMALS MAY BE DEPENDENT ON ALTERATIONS IN ACETYLCHOLINE AND CORTICOTROPIN RELEASING FACTOR EXPRESSION
1Program in Neuroscience, Graduate School of Biomedical Sciences and Professional Studies, Philadelphia PA, United States, 2Department of Neurobiology and Anatomy Drexel University College of Medicine, Philadelphia PA, United States
Sports‐related concussions (SRC, a subset of mild TBI) are a leading cause of long‐term cognitive deficits in adolescents. Either moderate TBI or chronic stress in animals lead to alterations in expression of choline acetyltransferase (ChAT) and corticotrophin releasing factor (CRF) within the medial septum (MS), contributing to impairments in spatial memory. Previously, we had reported that repeated mild injuries in adolescent male and female rats resulted in hippocampal‐dependent spatial memory deficits at 1‐and‐4‐weeks post‐injury in the novel object location task; only male brain‐injured animals exhibited significant deficits at 1 week whereas both male and female brain‐injured animals showed impairment at 4 weeks. We hypothesized that disrupted cholinergic transmission between the MS and hippocampus may be the mechanistic basis for these deficits, and that CRF expression in the amygdala regulated ChAT expression in the MS. Following behavioral assessment at each time point, rats were sacrificed for quantitative real‐time PCR and immunohistochemistry. Our data show that there is a decrease in ChAT immunoreactivity in the MS of male brain‐injured animals at 1‐and‐4‐weeks, but fewer ChAT(+) cells were observed in female brain‐injured animals only at the 4‐week time point. Whereas CRF immunoreactivity within the MS and amygdala showed no change in any brain‐injured animal, CRF mRNA within the amygdala was increased 1‐and‐4‐weeks post‐injury only in male brain‐injured animals. These results provide novel sex‐dependent associations between ChAT and CRF expression and cognitive impairments post‐injury, offering further insight into a potential mechanism of action.
Keywords: Neurotransmitter, Cognition/Learning/Memory, Gene Expression, Concussion/mTBI
PROTECTIVE AND RISK FACTORS FOR POST CONCUSSION SYMPTOMS AND RETURN TO PLAY OF NCAA COLLEGIATE ATHLETES: FINDINGS FROM THE NCAA‐DOD CARE CONSORTIUM
1Indiana University, Bloomington IN, United States, 2University of Texas, Austin TX, United States
The purpose of this study is to identify protective or risk factors for developing Post concussion syndrome (PCS) using medical histories, contact sport level, the side‐line concussion assessment tool (SCAT) and brief symptom inventory (BSI18) assessments at baseline and post‐injury. Medical histories, preseason baselines (n = 47,518), and post‐injury SCAT and BSI‐18 exams (n = 3,586) were analyzed for collegiate athletes in the NCAA‐DoD CARE Consortium. PCS is defined as cleared for full return to play (RTP) >48 days. At the preseason timepoint, mental health, learning disability, concussion, migraine histories, and sex have a minimal to large effect (d = 0.16‐0.99) on BSI18 and SCAT total scores. At the post‐injury time point, mental health and sex have a small effect on BSI18 and SCAT total scores (d = 0.23‐0.50). At post‐injury, mental health, learning disability, and female sex have a small effect on RTP (d = 0.14‐0.22). Odds ratios (OR) indicate mental health (OR = 1.51), BSI18 > 30 (OR = 1.73), SCAT >68 (OR = 2.02), loss of consciousness (OR = 1.45), female‐sex (OR = 1.39), limited contact sport athlete (OR = 1.33), and non‐NCAA athlete (OR = 2.10) are risk factors for developing PCS. Similarly, learning disability (OR = 0.42), prior concussion (OR = 0.57), migraine (OR = 0.78), non‐contact sport (OR = 0.94), or contact sport (OR = 0.43) are protective factors against developing PCS. A stepwise logistic regression model using these risk and protective variables does a poor job of predicting PCS.
Keywords: Behavioral Function, Concussion/mTBI
MILD TRAUMATIC BRAIN INJURY‐INDUCED BLOOD‐BRAIN BARRIER DISRUPTION INDUCES ATYPICAL NEURONAL PHENOTYPE
1University of Alabama at Birmingham, Birmingham AL, United States, 2Virginia Tech, Blacksburg VA, United States, 3Kenyon College, Gambier OH, United States
Mild traumatic brain injury (mTBI) is the most common and least studied type of TBI. Yet, mTBI can be sufficient to induce brain changes that might lead to consequences including sleep disturbances, cognitive impairment, mood swings, and post‐traumatic epilepsy. To interrupt the progression of these comorbidities, identifying early pathological events is key. Recent studies have demonstrated that microbleeds, caused by mechanical impact, are correlated with worse TBI outcomes. However, the mechanisms triggered by blood entrance in the brain that affect neurons are yet to be elucidated.
In this work, we used the a weight‐drop mouse model and used immunohistochemistry and histology to assess the expression of neuronal proteins after TBI. NeuN, Parvalbumin and CamKII expression was lost within minutes after the injury in areas with BBB disruption, but neurons remained alive, as demonstrated by Nissl staining. These changes persisted for at least 6 months after the injury. vGlut1/Homer1 and Golgi staining analysis revealed a decreased in post‐synaptic spines and changes in the spine width and type, being and indicative of functional consequences. A similar neuronal response was observed in an endothelial cell ablation mouse model in which BBB disruption was induced in absence of mechanical insult, demonstrating that BBB disruption alone is sufficient to induce these neuronal changes.
These results indicate that TBI‐induced BBB disruption is sufficient to induce long‐lasting changes in neuronal proteins expression and spines as early as five minutes after the injury. Future studies will address the functional consequences of these changes in neuronal circuits and behavior.
Keywords: Secondary Injury, Neurodegeneration, Blood Brain Barrier, Cell Death, Concussion/mTBI, Synaptic Function
TAU ASTROGLIOPATHY IN THE AFTERMATH OF REPETITIVE MILD TRAUMATIC BRAIN INJURY
1Roskamp Institute, Sarasota FL, United States, 2The Open University, Milton Keynes, United Kingdom, 3James A Haley VA, Tampa FL, United States, 4Barrow Neurological Institute, Phoenix AZ, United States
Repetitive mild traumatic brain injury (r‐mTBI) is a risk factor for neurodegenerative diseases such as chronic traumatic encephalopathy (CTE). Postmortem studies have identified tau astrogliopathy, as one of the pathological features of r‐mTBI. It remains unknown whether tau astrogliopathy induces astrocyte dysfunction, contributes to tau spreading or augments TBI mediated neurodegeneration. To begin to address these unknowns, we combined histopathological and single cell population RNAseq techniques to investigate outcomes in a conditional mouse model that allows genetic regulation of astrocytic tau expression after r‐mTBI. Methods: 3‐month‐old WT and GFAP‐P301L mice were exposed to our 20 hits r‐mTBI paradigm over a month. At 3‐months post‐last injury, brains were collected for histology, and magnetic activated (ACSA2+ astrocyte) cell sorting and RNAseq. In a parallel study, immediately post‐last injury, the expression of pathogenic tau in astrocytes was genetically silenced for 3 months by oral administration of doxycycline. Results: Gene ontology analysis revealed profound changes in tau bearing astrocytes from our mouse model, and similar effects were noted in micro‐dissected human astrocytes from CTE brains after gene array analyses. Notably, there was a prominent downregulation of mitochondrial bioenergetics and upregulation of apoptotic pathways. The histological analyses in the WT and GFAP‐P301L mice treated with doxycycline are currently ongoing. Conclusions: Thus far, our data reveal that tau bearing astrocytes may be neurotoxic to astrocytes and drive senescent pathways. Our future work will explore the specific mechanism driving these effects and the identification of novel (astrocyte cell‐specific) targets for therapeutic discovery.
Keywords: Astrocyte, Gene Expression, Cell Death, Chronic Traumatic Encephalopathy, Inflammation/Immune Function, Neuropathology
THE INFLUENCE OF HORMONAL CONTRACEPTIVES ON CONCUSSION RECOVERY IN COLLEGIATE ATHLETES: DATA FROM THE NCAA‐DOD CARE CONSORTIUM
1University Of South Carolina, Arnold School of Public Health, Columbia SC, United States, 2Prisma Health Children's Hospital, Columbia SC, United States, 3Cummins School of Medicine, Hotchkiss Brain Institute, Calgary, Canada, 4Indiana University School of Medicine, IU Health Neuroscience Center, Indianapolis IN, United States, 5Medical College of Wisconsin, Center for Neurotrauma Research, Milwaukee WI, United States, 6University of Michigan, Michigan Concussion Center, Ann Arbor MI, United States
The hormonal withdrawal hypothesis suggests that following concussion women may experience increased symptom burden and a longer recovery time due to a reduction in progesterone. Hormonal contraception use may therefore be protective against these effects by artificially stabilizing hormone levels. The objective of our investigation was to longitudinally examine the relation of hormonal contraception use and concussion outcomes. Eighty‐six female collegiate athletes reporting hormonal contraception use (HC+) and 86 matched control athletes reporting no use (HC‐) completed assessments at baseline, 24‐48 hours after sustaining a concussion, and when cleared for unrestricted return to play as part of the NCAA‐DoD CARE Consortium Research Initiative. The Sports Concussion Assessment Tool (SCAT)‐Symptom Scale was used to evaluate symptoms and Immediate Post‐concussion Assessment and Cognitive Testing (ImPACT) was used to examine cognitive function. The average number of days from injury to return to play did not differ between groups. Group X time interactions revealed no significant differences in SCAT symptom scores nor ImPACT composite scores at baseline or any post‐injury timepoint. However, the HC+ group displayed higher average scores than the HC‐ group for ImPACT verbal memory across all timepoints (p = 0.048). Our findings suggest that hormonal contraception use does not influence recovery trajectory, symptoms, nor recovery of cognitive function following concussion.
Keywords: Cognition/Learning/Memory, Concussion/mTBI
THE INFLUENCE OF REPETITIVE EXPOSURE TO SUB‐CONCUSSIVE HEAD IMPACTS ON AUDITORY AND COGNITIVE PROCESSING
Ms. Nathalee Ewers1,
1McMaster University, Hamilton, Canada, 2University of South Carolina, Columbia SC, United States
There is increasing evidence that exposure to repetitive sub‐concussive impacts may negatively impact brain health and cognition, even without the clinical presentation of concussion. Event‐related brain potentials (ERPs) have shown utility for detecting deficits in sensation, perception, and cognition in concussed athletes. Our study sought to use ERPs to investigate the influence of repetitive sub‐concussive impacts on cognitive processing during auditory task performance. Thirty‐eight Canadian college football players completed computerized cognitive tasks at baseline and after their sports season; and 18 non‐contact athletes completed the same tasks at a single timepoint throughout their season. A passive auditory task that did not require participants to respond was used to assess the mismatch negativity (MMN) ERP component, which represents automatic pre‐attentive processing. In addition, an active auditory oddball task that required participants to respond to an infrequently presented stimulus was used to assess the N2b, P3a, and P3b ERP components, which index inhibitory processing, stimulus discrimination, and attention resource allocation respectively. In comparison to non‐contact athletes, football players exhibited reduced MMN, P3a, and P3b amplitudes (all ps <0.05). However, there were no group differences for the N2b amplitude. Our results provide evidence that repetitive sub‐concussive impacts may negatively impact both pre‐attentive and attentive processes, but not inhibitory processes during auditory tasks. These deficits may carry real‐world implications for athletes, particularly for those competing in noisy environments.
Keywords: Concussion/mTBI, Electrophysiology, Attention
TIME‐COURSE CHANGES IN NEAR POINT OF CONVERGENCE ACROSS HIGH SCHOOL FOOTBALL SEASON
1Indiana University ‐ Bloomington, Bloomington IN, United States
This study investigated the effects of repetitive subconcussive head impacts on near point of convergence (NPC) over the course of a high school football season. A total of 99 healthy adolescent high school American football players and 19 healthy adolescent high school non‐contact athletes (tennis or cross country) participated in the study and attended data collection sessions at preseason, three mid‐season time points (August, September, and October), and a post‐season follow up. At each time point, NPC was assessed twice and then averaged. The effects of group, time, and group‐by‐time interaction on NPC, as well as association between NPC and head impact kinematics (frequency and peak‐linear/rotational accelerations, assessed by a sensor‐installed mouthguard), were assessed using a mixed‐effects regression model. The football group exhibited increased NPC relative to the non‐contact control group at all three mid‐season time points, as illustrated by significant group‐by‐time interactions (estimate [95%CI]: August, 1.90 [0.90,2.89], p < 0.001; September, 1.48 [0.47,2.49], p = 0.004; October, 1.22 [0.22,2.21], p = 0.017) and at post‐season follow up (2.18 [1.20,3.17], p < 0.001). NPC did not change over time for the non‐contact athletes. Within the football group, NPC was increased relative to pre‐season at the three mid‐season time points. However, the increase in NPC did not correlate with any head impact kinematics. These findings suggest that football players experienced chronic deficits in oculomotor function over the course of a season, but there was no dose‐dependent relationship between NPC and head impact kinematics.
Keywords: Biomarker, Concussion/mTBI, Vestibular
MECHANISMS UNDERLYING TLR4 MODULATION OF DENTATE INHIBITION FOLLOWING BRAIN INJURY
1University Of California, Riverside, Riverside CA, United States
Neuroimmune changes following trauma may play a critical role in the development of post traumatic epilepsy (PTE). Toll‐Like Receptor 4 (TLR4), an innate immune receptor, is enhanced after brain injury and is implicated in epileptogenesis. We find that pharmacological suppression of TLR4 after fluid percussion injury (FPI), a model of concussive brain injury, reduces seizure susceptibility and memory deficits but exhibits opposing effects in the uninjured brain by mechanisms that are not yet fully characterized. This study examines the contribution of TLR4 modulation cell‐type specific GABAergic inhibition. Using whole‐cell voltage clamp from hippocampal dentate granule cells in response to perforant‐path stimulation, we found that FPI in mice reduced evoked IPSC amplitude. TLR4 antagonist bidirectionally modulated evoked IPSC amplitude in sham and injured mice, demonstrating that TLR4 signaling modifies dentate inhibition. FPI reduced afferent‐evoked IPSC amplitude in granule cells that was reversed with TLR4 antagonist. Immunostaining revealed TLR4 modulation of GABAAR α1 and γ2 subunit expression may be specific to dentate regions. Optogenetic stimulation of somatostatin (SST) or parvalbumin (PV) interneuron subtypes identified that TLR4 antagonism selectively modulated GABAergic synapses from SST interneurons after injury but not in controls, while having little effect on PV synapses. These findings indicate that TLR4 signaling leads to cell‐type specific differential modulation of GABA currents in granule cells from control and FPI mice. Acute targeting of TLR4 signaling after brain injury may limit post‐injury increases in dentate excitability by promoting synaptic GABAergic inhibition.
Keywords: Epilepsy/Seizure, Concussion/mTBI, Electrophysiology, Inflammation/Immune Function
EFFECTS OF CAFFEINE ON SUBJECTIVE MEASURES OF CLINICAL OUTCOME AND RECOVERY FOLLOWING CONCUSSION IN ADOLESCENTS
1Arnold School of Public Health, University Of South Carolina, Columbia SC, United States, 2Department of Pediatrics, Prisma Health Children's Hospital, Columbia SC, United States
Caffeine is the most widely consumed drug in the world and is the only psychoactive compound legally available to minors. Consumption is becoming more prevalent within the adolescent population, often coinciding with recreational activities where incidence of concussion is high. However, the influence of caffeine on concussion pathology is not well established. Therefore, the purpose of the present study was to determine if caffeine impacts clinical outcome and recovery in adolescents following concussion. Thirty‐four concussed adolescents who habitually consume caffeine (CAF+; 18 males, 16 females; 15 ± 1 years) and seventeen matched non‐consumers (CAF‐) completed a comprehensive clinical evaluation on two separate occasions at a local paediatric concussion clinic. The Rivermead Post‐Concussion Symptoms Questionnaire (RPQ), Depression Subscale of the Beck Youth Inventories ‐ Second Edition (BYI‐2), and The Behaviour Rating Inventory of Executive Function (BRIEF) were used to assess somatic, affective, and cognitive symptomatology at 13 ± 7 (Eval1) and 30 ± 12 days (Eval2) post injury. Results indicated no significant main effects of group or group X time interactions in RPQ symptomology, or BRIEF executive function. However, a group X time interaction for BYI‐2 revealed CAF+ had a significantly higher mean score than CAF‐ for depressive symptoms at Eval2 (P = 0.009). In conclusion, these findings suggest caffeine attenuates the recovery of symptoms associated with depression in adolescents' post‐concussion. Future studies should elucidate whether a dose response exists between level of habitual caffeine consumption and severity of psychiatric outcome and recovery post‐concussion.
Keywords: Pediatric, Behavioral Function, Depression, Concussion/mTBI
COGNITIVE OUTCOMES OF HEAD IMPACT EXPOSURE IN YOUTH ICE HOCKEY
1Wake Forest School Of Medicine Dept. of Neuroscience, Winston Salem NC, United States, 2Wake Forest School Of Medicine Dept. of Biomedical Engineering, Winston Salem NC, United States, 3Virginia Tech ‐ Wake Forest University School of Biomedical Engineering, Winston Salem NC, United States, 4Atrium Health Wake Forest Baptist, Dept. of Neuropsychology, Winston Salem NC, United States
This study aimed to examine relationships between head impact exposure (HIE) metrics and neurocognitive outcomes in non‐concussed youth hockey athletes following a single season of play. 15 athletes ages 12‐16 at preseason were recruited from a local youth hockey organization and were fitted with a custom instrumented mouthpiece for measuring head kinematics. HIE metrics recorded included mean and 95th percentile peak resultant linear acceleration (PLA), rotational velocity (PRV), and rotational acceleration (PRA). Athletes completed a pre‐ and post‐season cognitive exam which included subtests from the NIH Toolbox and ImPACT test. Preliminary relationships between HIE metrics and cognitive outcomes were assessed using linear regression models with estimated IQ, years of hockey experience, and interval between last head impact exposure and post‐season test date as covariates. We recorded 894 video‐verified contact scenarios with the mouthpiece, with a mean [95th percentile] PLA, PRV, and PRA of 9.14 [21.65] g, 8.78 [17.84] rad/s, and 677.4 [1478.1] rad/s2 respectively. Increased mean PRA and 95th percentile PLA were significantly associated with declining visual (mean PRA: p = .004, R2 = .511; 95th percentile PLA: p = .006, R2 = .512) and verbal memory (mean PRA: p = .0008, R2 = .590; 95th percentile PLA: p = .005, R2 = .472) ImPACT scores. Mean PLA was similarly associated with verbal memory (p = .0002, R2 = .705). Mean and 95th percentile PRV were not associated with declines in cognition. These relationships were consistent across covariates. In summary, we observed significant relationships between mean and 95th percentile head accelerations and cognitive outcomes among youth hockey athletes after one season of play, warranting further study.
Keywords: Pediatric, Cognition/Learning/Memory, Concussion/mTBI, Biomechanics
INFLUENCE OF FAMILY HISTORY OF MIGRAINE ON PATIENT REPORTED OUTCOME MEASURES FOLLOWING ADOLESCENT CONCUSSION
1Arnold School of Public Health, University Of South Carolina, Columbia SC, United States, 2Department of Pediatrics, Prisma Health Children's Hospital, Columbia SC, United States of America
Outcomes following adolescent concussion are highly variable and difficult to predict. Increased understanding of the factors that contribute to variability of symptoms and their recovery is needed to improve prognosis of outcomes. Family history of migraine is a known predictor of post‐concussive headache, but its relationship to other symptoms and their recovery remains unknown. A prospective cohort design was utilized to examine the influence of family history of migraine and its interactions with biological sex on initial symptom reports and recovery of symptoms following adolescent concussion. We studied 168 concussed adolescents, including 84 with family history of migraine and 84 without family history of migraine matched on demographic and injury characteristics. Subscales of the Rivermead Post‐Concussion Questionnaire (RPQ) were used to measure affective, cognitive, and somatic symptoms at two timepoints following concussion. Subjects with Family History of migraine initially reported more somatic symptoms than subjects without Family History (p < 0.001) and reported less recovery of somatic symptoms between timepoints (p = 0.002). A significant interaction between Family History of migraine and Sex (p = 0.03) also indicated that Females with Family History of migraine initially reported more somatic symptoms than Males with Family History (p = 0.02). No significant main effects or interactions were found for initial reports or recovery of affective or cognitive symptoms. These findings demonstrate that family history of migraine influences initial presentation and recovery of somatic symptoms in concussed adolescents and can be used to improve prediction of outcomes following adolescent concussion.
Keywords: Pediatric, Genetic Factors, Concussion/mTBI
FAMILY HISTORY OF MIGRAINE DOES NOT INFLUENCE COGNITIVE PERFORMANCE FOLLOWING ADOLESCENT CONCUSSION
1Arnold School of Public Health, University Of South Carolina, Columbia SC, United States, 2Department of Pediatrics, Prisma Health Children's Hospitall, Columbia SC, United States
Outcomes following adolescent concussion are highly variable and difficult to predict. Increased understanding of the factors that contribute to variability of symptoms and their recovery is needed to improve prognosis of outcomes. Family history of migraine is a known predictor of post‐concussive headache, but its relationship to other symptoms and their recovery remains unknown. A prospective cohort design was utilized to examine the influence of family history of migraine and its interactions with biological sex on cognitive performance outcomes and recovery following adolescent concussion. Fifty‐five concussed adolescents with a family history of migraine and fifty‐five concussed adolescents without a family history of migraine were matched on demographic and injury characteristics. The Groton Maze Learning (GML), Groton Maze Recall (GMR), and Two Back (TWOB) tasks from the Cogstate computerized cognitive assessment were used to measure executive function and cognition. Initial outcomes were measured at first evaluation, and recovery was determined by the difference between measures at evaluation one and evaluation two. Two‐way ANOVAs were conducted on each measure to determine the main effects of family history of migraine and any interaction effects between family history of migraine and sex. No significant main or interaction effects were found. These findings demonstrate that family history of migraine does not influence adolescents' initial cognitive performance or recovery of cognitive performance following concussion.
Keywords: Pediatric, Cognition/Learning/Memory, Genetic Factors, Concussion/mTBI
LEVELS OF LYSOPHOSPHATIDIC ACIDS IN THE CEREBROSPINAL FLUID (BUT NOT PLASMA) CAN BE A SUITABLE BIOMARKER OF BLAST‐INDUCED TRAUMATIC BRAIN INJURY
1Walter Reed Army Institute of Research, Silver Spring MD, United States
Blast‐induced traumatic brain injury (bTBI) has been identified as the signature injury of Operation Iraqi Freedom and Operation Enduring Freedom. Development of suitable biomarkers that could aid in the proper diagnosis and prognosis of both acute and chronic bTBI is essential. Lysophosphatidic acid (LPA) is a bioactive phospholipid generated by activated platelets, astrocytes, choroidal plexus cells and microglia and is reported to play major roles in stimulating inflammatory processes. The levels of LPA in the cerebrospinal fluid (CSF) have been reported to increase acutely after brain injuries unrelated to blast, prompting the current interest in bTBI. In the present study, we have evaluated the utility of LPA levels measured in the CSF and plasma of rats as acute and chronic biomarkers of bTBI using an advanced blast simulator. In the CSF, many LPA species were increased at acute time points, returned to normal levels at 1 month, but then increased again at 6 months and 1 year post‐blast. The changes in LPA levels in the CSF negatively correlated with neurobehavioral functions in the rats. In the plasma, several LPA species were increased acutely and returned to normal levels by 24 hr, but levels of many LPA species were decreased significantly at 1 year post‐blast. The decrease in LPA species in the plasma at 1 year post‐blast was associated with decreased levels of lysophosphatidyl choline, suggesting a defective upstream biosynthetic pathway of LPAs in the plasma. Thus, CSF (but not plasma) levels of LPAs can be a suitable biomarker of bTBI.
Keywords: Biomarker, Blast, Concussion/mTBI, Inflammation/Immune Function
CIRCADIAN AND SLEEP DISRUPTION IN A MOUSE MODEL OF CHRONIC TRAUMATIC BRAIN INJURY
1University of Florida, Gainesville GA, United States
Keywords: Sleep, Concussion/mTBI
JUVENILE CONCUSSION RESULTS IN ACCELERATED AGING ACCOMPANIED BY EVOLVING REGIONAL BRAIN TISSUE MODIFICATIONS: A DTI INVESTIGATION
Dr. Jeong Bin Lee4, Dr. Beatriz Rodriguez‐Grande2, Ms. Marie Line Fournier2, Ms. Tifenn Clément2, Dr. Aurélien J Trotier2, Dr. Sylvain Miraux2, Dr. Nicola Marchi3, Dr. Jerome Badaut2,
1Department of Pediatrics, University of California, Irvine, Irvine CA, United States, 2Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/Université de Bordeaux, Bordeaux, France, 3Cerebrovascular and Glia Research Laboratory, Department of Neuroscience, Institute of Functional Genomics , Montpellier, France, 4Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda CA, United States
Keywords: Behavioral Function, Aging, Imaging, Concussion/mTBI
REGENERATION OF SPINAL CORD NEURONS AFTER INJURY VIA IN SITU NEUROD1‐MEDIATED ASTROCYTE‐TO‐NEURON CONVERSION
1Augusta University, Augusta GA, United States
Spinal cord injury (SCI) often leads to impaired motor and sensory functions, partially because the injury‐induced neuronal loss cannot be easily replenished through endogenous mechanisms. In vivo neuronal reprogramming has emerged as a novel technology to regenerate neurons from endogenous glial cells by forced expression of neurogenic transcription factors. We have previously demonstrated successful astrocyte‐to‐neuron conversion in mouse brains with injury or Alzheimer's disease by overexpressing a single neural transcription factor NeuroD1 via retroviruses. Here we demonstrate regeneration of dorsal spinal cord neurons from reactive astrocytes after SCI via adeno‐associated virus (AAV), a more clinically relevant gene delivery system. We find that NeuroD1 converts reactive astrocytes into neurons in the dorsal horn of stab‐injured spinal cord with high efficiency (∼95%). Interestingly, NeuroD1‐converted neurons in the dorsal horn mostly acquire glutamatergic neuronal subtype, expressing spinal cord‐specific markers such as Tlx3 but not brain‐specific markers such as Tbr1, suggesting that the astrocytic lineage and local microenvironment affect the cell fate of conversion. Electrophysiological recordings show that the NeuroD1‐converted neurons can functionally mature and integrate into local spinal cord circuitry by displaying repetitive action potentials and spontaneous synaptic responses. We further show that NeuroD1‐mediated neuronal conversion can occur in the contusive SCI model, allowing future studies of evaluating this reprogramming technology for functional recovery after SCI. In conclusion, this study may suggest a paradigm shift for spinal cord repair using in vivo astrocyte‐to‐neuron conversion technology to generate functional neurons in the grey matter.
Keywords: Astrocyte, Regeneration & Plasticity, Neurogenesis
REPETITIVE TRAUMATIC BRAIN INJURY LEADS TO PERSISTENT BEHAVIORAL DEFICITS AND TRANSCRIPTIONAL CHANGES IN A MOUSE MODEL OF ALZHEIMER'S DISEASE
1Institute for Behavioral Medicine Research , Columbus OH, United States, 2Department of Neuroscience , Columbus OH, United States
Apolipoprotein‐ɛ4 (APOE‐ɛ4) confers increased genetic risk for late‐onset Alzheimer's disease (LOAD) and has simultaneously been associated with poor outcome after single incident and repetitive traumatic brain injury (rTBI). Recent evidence demonstrates that APOE and Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) work together to influence microglial activity within the brain. The interrelationship between APOE and TREM2 after rTBI remains unknown. To investigate this interaction, we used the Closed Head Impact Model of Engineered Rotational Acceleration (CHIMERA) on a mouse model containing the APOE‐ɛ4 and TREM2‐R47H risk variants. We hypothesized that rTBI would exaggerate the neuroinflammatory response in mice at risk for LOAD. 10‐week‐old, male and female APOE‐ɛ4 /TREM2R47H mice received either 0, 1, 2, or 3 TBIs separated by 24 hours respectively. Behavioral, transcriptional, and immunohistological experiments were completed through 30 days post‐injury(DPI). We found increased presence of infiltrating CD45 positive cells in both the cortex and hippocampus 7DPI. While Iba1 percent area remained similar between experimental groups 7DPI, rTBI mice displayed increased cortical gene expression of Trem2, Interlukin‐6, and Tumor Necrosis Factor alpha . This finding was accompanied by exacerbated spatial working memory deficits in the Y‐Maze 7 and 14DPI. rTBI increased disinhibition in elevated zero maze 29 DPI; however, no significant differences in cortical and hippocampal CD45 and Iba1 labelling were identified between groups 30DPI. These data suggest that APOE‐ɛ4/TREM2R47H alter the acute response to rTBI and compromise functional recovery. However, more work is needed to define the chronic inflammatory milieu and long‐term outcome.
Keywords: Microglia, Neurodegeneration, Inflammation/Immune Function
REPETITIVE WEAPONRY‐TYPE BLAST‐INDUCED TRAUMATIC BRAIN INJURY IN RODENTS
1Laboratory of Molecular Biology, Research & Development, Department of Veterans Affairs, VA New Jersey Health Care System, East Orange NJ, United States, 2Neurobehavior Research Laboratory, Research & Development, Department of Veterans Affairs, VA New Jersey Health Care System, East Orange NJ, USA, 3Rutgers University, School of Graduate Studies, Newark NJ, USA, 4Center for Injury Biomechanics, Materials, and Medicine, Department of Biomedical Engineering, New Jersey Institute of Technology, Newark NJ, USA, 5Pharmacology, Physiology, and Neuroscience, Rutgers‐New Jersey Medical School, Newark NJ, USA
Mild traumatic brain injuries (TBIs) among military personnel are most frequently caused by blast exposures from a variety of heavy weaponry, including 50‐caliber rounds, grenades, and breaching devices during training and active service. We are interested in neuronal health and understanding mechanisms to improve cognitive outcomes for Veterans and others. Our data from other repetitive closed‐head injury models indicate that significant memory deficits are accompanied by upregulation of neurodegeneration‐associated TDP‐43 at chronic post‐injury time points. The blast profile chosen for this injury model reproduces the heavy weaponry environment and consequent microsecond pressure waves in an established shock tube system. Rodents were subjected to five shock waves at 1‐min intervals with monitored peak overpressure at 10‐12 psi. We evaluated behavioral effects, including Y‐maze testing for spatial memory deficits, and have also been examining neuropathological changes by immunohistochemistry as well as changes in gene expression at the mRNA and protein levels. Results indicated that inflammatory responses are induced. For example, the rat hippocampus displayed an upregulation greater than 2‐fold of NLRP3 by immunohistochemistry (p < 0.01) and Western immunoblotting (p < 0.05, n = 3 per group) through 35 days post‐injury. Through these experiments, we hope to obtain a better understanding of the dysregulations triggered by repetitive weaponry‐type blast exposure and identify therapeutic targets that could lead to strategies to improve post‐injury outcomes.
Keywords: Cognition/Learning/Memory, Blast, Neurodegeneration, Gene Expression
CHRONIC ELEVATION OF SERUM S100B BUT NOT NEUROFILAMENT‐LIGHT DUE TO FREQUENT CHOKING/STRANGULATION DURING SEX IN YOUNG ADULT WOMEN
1Department of Kinesiology, Indiana University School of Public Health‐Bloomington, Bloomington IN, United States, 2Department of Applied Health Science and The Center for Sexual Health Promotion, Indiana University School of Public Health, Indiana University, Bloomington IN, United States, 3Department of Pediatrics, Indiana University School of Medicine, Indianapolis IN, United States, 4Department of Kinesiology, Indiana University School of Public Health and Program in Neuroscience, The College of Arts and Sciences, Indiana University, Bloomington IN, United States
Keywords: Biomarker, Astrocyte, Hypoxia/Ischemia, Inflammation/Immune Function
CHANGES IN PERICYTES IN A RAT MODEL OF BLAST‐INDUCED TRAUMATIC BRAIN INJURY
1Henry M Jackson Foundation, Silver Spring MD, United States, 2Parsons Corporation, United States, 3Naval Medical Research Center, Silver Spring MD, United States
The incidence of blast‐induced traumatic brain injury (bTBI) has been a persistent risk for neurological impairment in the military population, yet its detailed pathophysiology remains to be fully investigated. Brain pericytes play a pivotal role in maintaining vascular stability and in pathophysiological processes after bTBI. In this study we used immunohistochemistry combined with in situ RNA hybridization and electron microscopy techniques to investigate blast‐induced temporal changes in pericyte markers including Platelet‐Derived Growth Factor Receptor Beta (PDGFR‐β) and Neural/Glial Antigen 2 (NG2) in a rat model of bTBI. Assessments were performed at 2‐3 hours (h), 1, 3, 14, and 28 days after exposure to a single 132 kPa blast (n = 5/group). A sham group (n = 5) was treated similar to blast groups except for exposure to blast. The localization of the PDGFR‐β and NG2 in blood vessels was visualized by double labeling with the vascular smooth muscle marker, smoothelin and the endothelial cell marker, platelet endothelial cell adhesion molecule (PECAM). Compared with the sham group, the immunofluorescence intensities of PDGFR‐β and NG2 were significantly decreased acutely (2‐3 h and 1day post‐blast, respectively) and chronically (28 days post‐blast). A significant blast‐induced decrease in the mRNA expression of PDGFR‐β (at all time points) and NG2 (1 day onwards) was also observed. Ultrastructural changes including swelling and migration of pericytes were visible at all post‐blast time points. Our findings show that blast exposure leads to acute and chronic impairment of brain pericytes which may have a role in the development of pathology following bTBI.
Keywords: Blast, Blood Brain Barrier, Imaging
IMPROVEMENT IN FUNCTIONAL CONNECTIVITY AND BEHAVIOR DEFICITS AFTER FPI THROUGH TRKB RECEPTOR ACTIVATION
1Neurosurgery, Los Angeles CA, United States, 2UCLA Brain Injury Research Center, Los Angeles CA, United States, 3Dept. Integrative Biology and Physiology, Los Angeles CA, United States
R13 an agonist of the Brain‐derived neurotrophic factor (BDNF)/tropomyosin‐related kinase B (TrkB) receptor has been shown to be neuroprotective. In this study R13 was tested for its ability to improve deficits in behavior and functional connectivity in the brain following moderate Traumatic brain Injury (mTBI).
Adult Sprague Dawley rats were injured using a lateral fluid percussion injury (FPI) rodent model and R13 or vehicle was administered daily (7.25 mg/kg, i.p.) from 1‐7d post‐injury.
In both male and female, vehicle‐treated, injured rats showed significant deficits compared to sham‐controls in spatial working memory on the Barnes Maze task at 6d post‐injury which was mitigated in injured rats by R13 intervention. Vehicle‐treated injured rats showed a moderate decrease in the time spent and distance travelled in the open arms of the elevated plus‐maze compared to sham‐controls. R13 intervention largely prevented these effects.
Resting state functional connectivity (FC) data were acquired at 7d post‐injury and were post‐processed to determine differences in brain wide FC after correction for multiple region comparison. Deficits in FC occurred in several brain circuits in vehicle‐treated mTBI rats compared to shams, including thalamic, hippocampal, striatal, and sensory/motor cortex. Intervention with R13 resulted in significant increases in FC in the circuits that showed deficits post‐TBI (P < 0.01, FDR corrected).
This study revealed that R13 counteracted cognitive deficit effect post‐TBI, and that FC deficits in circuits related to this altered function were also ameliorated by TrkB activation. These findings delineate the therapeutic potential of R13 in the management of TBI.
Keywords: Behavioral Function, Cognition/Learning/Memory, Imaging, Concussion/mTBI, Metabolism/Energetics
PEG BASED HA‐DEXAMETHASONE HYDROGEL REDUCED INFLAMMATORY RESPONSE AND IMPROVES MOTOR AND COGNITIVE FUNCTION IN A RAT MODERATE CONTROLLED CORTICAL IMPACT (CCI) TBI MODEL
1Drug Design, Development and Delivery Laboratory, Clemson University, Greenville SC, United States, 2MicroEnvironmental Engineering Laboratory, Clemson University, Clemson SC, United States, 3Brain Trauma Neuroprotection Branch, Walter Reed Army Institute of Research (WRAIR), Silver Spring MD, United States
Secondary injury following traumatic brain injury (TBI) initiates an inflammatory response that can be detrimental to the tissue and limits functional recovery. Dexamethasone (DX), a synthetic glucocorticoid, is known to minimize the neurotoxic effects and improve recovery by attenuating inflammation and reducing early expression of pro‐inflammatory cytokines associated with activation of microglia/infiltrated macrophages. In this study we investigated the effects of locally applied hydrolytically degradable hydrogel composed of polyethylene glycol‐bis‐(acryloyloxy acetate) (PEG‐bis‐AA) and dexamethasone‐conjugated hyaluronic acid (HA‐DXM) hydrogels on secondary injury, motor, and cognitive function recovery in a rat moderate CCI model. We observed that PEG‐bis‐AA/HA‐DXM hydrogel treatment immediately after injury significantly improved motor function by rotarod and beam walk. For histological analysis at 7 DPI, we observed significantly reduced lesion volume in hydrogel treated groups compared to that in untreated TBI group by NISSL staining. We also observed the number of ED1+ (activated microglia/infiltrated macrophage) cells and the fluorescence intensity of GFAP (expressed in astrocytes) in the hydrogel treated group were lower than that in untreated TBI group. For the cognitive function by Morris Water Maze, PEG‐bis‐AA/HA‐DXM treated rats demonstrated a decreased time to find hidden platform (target), decreased distance to swim to find hidden platform, and decreased percent time to swim in border when compared to TBI untreated rats on both training period and the probe test. Histological analyses for inflammatory response and neuroprotection using brain tissue harvested at 2 weeks post‐injury are in progress.
Acknowledgement: US Department of ACCCRP under award number W81XWH‐20‐C‐0114
Keywords: Neuroprotection, Secondary Injury, Drug Delivery, Therapeutics/Drug Discovery, Inflammation/Immune Function
GAZE BEHAVIOR STRATEGIES AMONG SYMPTOMATIC AND ASYMPTOMATIC INDIVIDUALS FOLLOWING CONCUSSIVE BRAIN INJURIES
1University of South Carolina, Columbia SC, United States
Keywords: Biomarker, Behavioral Function, Executive Function, Concussion/mTBI
BEHAVIORAL PERFORMANCE AMONG SYMPTOMATIC AND ASYMPTOMATIC INDIVIDUALS WITH A HISTORY OF CONCUSSION: COMPARISON WITHIN DISCRETE AND CONTINUOUS TASK PARADIGMS
1University Of South Carolina, Columbia SC, United States
Keywords: Behavioral Function, Executive Function, Concussion/mTBI
TRAUMATIC BRAIN INJURY PATIENT TRAJECTORIES IN THE ICU: FULL‐CONTEXT MODELLING WITH ARTIFICIAL INTELLIGENCE FOR DYNAMIC ORDINAL PROGNOSES
1Division of Anaesthesia, University of Cambridge, Cambridge, United Kingdom, 2Department of Computer Science and Technology, University of Cambridge, Cambridge, United Kingdom, 3Division of Psychology, University of Stirling, Stirling, United Kingdom, 4Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore MD, United States of America, 5Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands, 6Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
Traumatic brain injury (TBI) patient trajectories in the ICU are variable and poorly understood. There are no evidence‐based methods to determine the evolution of a patient's prognosis or the individualized effect of time‐sensitive treatments. Previously, we developed ordinal models to predict individual scores of the Glasgow Outcome Scale – Extended (GOSE) at 6 months post‐injury from all clinical information available at 24 hours after ICU admission. In this work, we aimed to extend this strategy to dynamically interpret all clinical events in real‐time to model the longitudinal evolution of TBI patient prognoses in the ICU. From a prospective cohort (n = 1,550, 65 centres) in the ICU stratum of the Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER‐TBI) patient dataset, we extracted all information collected during ICU stay (1,152 variables) as well as 6‐month GOSE. We trained recurrent neural‐network models on a token‐embedded representation of all variables to return ordinal prognoses of 6‐month GOSE every 2 hours. Then, we determined the impact of clinical events on each individual's outcome at different points of ICU stay with Shapley additive explanation values. With repeated k‐fold cross‐validation (20 repeats, 5 folds), we observed that the all‐variable dynamic ordinal model achieves significantly higher (95% CI) discrimination of individual GOSE than the all‐variable static (first 24 hours) baseline model only 8 hours after admission (ordinal c‐index: 0.76 [0.74‐0.77]). The dynamic model achieves moderate calibration at each threshold of GOSE. Our results validate dynamic AI modelling for mapping TBI trajectories and predicting individualized treatment effects for decision support.
Keywords: Monitoring, Computational/Modeling, Neurocritical Care, Informatics
LONGITUDINAL DYNAMICS OF MICROVASCULAR RECOVERY AFTER ACQUIRED CORTICAL INJURY
Xiaoxiao Lin1, Lujia Chen1,
1Department of Anatomy and Neurobiology, University of California, Irvine, Irvine CA, United States, 2Department of Pediatrics, University of California, Irvine, Irvine CA, United States, 3Department of Physiology and Biophysics, University of California, Irvine, Irvine CA, United States, 4Department of Biomedical Engineering, University of California, Irvine, Irvine CA, United States, 5Center for Neural Circuit Mapping, University of California, Irvine, Irvine CA, United States
Traumatic brain injuries (TBI) damage cortical vasculature, which in turn impairs blood flow to injured tissues. There are reports of vascular morphological recovery following TBI, but the remodeling process has not been examined longitudinally in vivo. To fill this gap, we evaluated the longitudinal and dynamic microvascular recovery and remodeling up to 2 months post‐injury using live brain miniscope and 2‐photon microscopic imaging, providing high spatial and temporal resolution in vivo. Vessel painting documented the initial loss and subsequent temporal morphological vascular recovery at the injury site. Miniscopes were used to longitudinally image the temporal dynamics of vascular repair in vivo after TBI in individual mice. We observed near‐immediate nascent growth of new vessels in and adjacent to the injury site that peaks between 14‐21 days post‐injury (dpi). 2‐photon microscopy confirms new vascular growth and demonstrates differences between cortical layers after TBI: large vessels persist in deeper cortical layers (>200 μm), while superficial layers exhibit a dense plexus of fine (often non‐perfused) vessels displaying regrowth. Functionally, blood flow increases mirror increasing vascular density. Filopodia development and endothelial sprouting is measurable within 3 dpi and transforms regions devoid of vessels into dense vascular plexus in which new vessels become increasingly perfused. Within 7 dpi, blood flow is observed in these nascent vessels. Behavioral analysis reveals improved vascular modulation after 9 dpi, consistent with vascular regrowth. We conclude that morphological recovery events are closely linked to functional recovery of blood flow to the compromised tissues, which subsequently leads to improved behavioral outcomes.
Keywords: Imaging, Vascular, Cerebral Blood Flow
TRANSFORMING RESEARCH & CLINICAL KNOWLEDGE IN GERIATRIC TRAUMATIC BRAIN INJURY (TRACK‐GERI): PREVALENCE AND PREDICTORS OF CAREGIVER STRAIN AT 2‐WEEKS POST‐INJURY AMONG CAREGIVERS OF OLDER ADULTS WITH MILD TRAUMATIC BRAIN INJURY
1UCSF, San Francisco CA, United States, 2University of Pittsburgh, Pittsburgh PA, USA, 3University of Washington, Seattle, Seattle WA, USA, 4MedRythyms , Portland OR, USA
Keywords: Aging, Concussion/mTBI
INTRAVENTRICULAR ZICONOTIDE AS A NOVEL THERAPY FOR NEUROPROTECTION FOLLOWING LATERAL FLUID PERCUSSION INJURY IN A RAT MODEL
1University Of California, Davis, School Of Medicine, Sacramento CA, United States, 2Department of Neurological Surgery, University of California, Davis, Sacramento CA, United States, 3Center for Neuroscience, University of California, Davis, Davis CA, United States
Traumatic brain injury (TBI) is a major source of morbidity and mortality worldwide. In previous studies, intravenous ziconotide, a selective N‐type voltage‐gated calcium channel blocker, reduced brain calcium accumulation, improved brain mitochondrial respiration, and improved cognitive and motor outcomes in rodent models of TBI. Attempts to translate intravenous ziconotide therapy to humans were halted due to peripheral side‐effects. However, ziconotide is now FDA‐approved for treatment of severe pain syndromes when administered intrathecally instead of intravenously. We hypothesize that intraventricular administration of ziconotide following TBI will improve cognitive and motor function in the absence of significant side effects.
Male Sprague‐Dawley rats underwent sham (n = 11) or lateral fluid percussion (LFP) injury (n = 21). One‐hour post‐injury, rats received either an intraventricular injection of saline (n = 11 sham, n = 11 LFP) or ziconotide (n = 10 LFP). A catheter was implanted in the left lateral ventricle and connected to an Alzet micro‐osmotic pump to allow for 72 hours of continuous infusion (saline or ziconotide). Motor and cognitive outcomes were evaluated using Rotarod (days 3,5,7,9,16,22), Morris water maze (MWM; days 10‐15), and novel object recognition task (NOR; day 17).
TBI‐saline rats performed significantly worse than shams on rotarod (p < 0.005) and MWM (p < 0.01), and showed no preference for the novel object. Ziconotide treated rats had an intermediate phenotype on MWM and had a significant preference for the novel object (p < 0.01). Ziconotide treatment did not significantly improve motor function on the rotarod task. These findings support centrally delivered ziconotide as a potential neuroprotective agent to improve cognitive performance following TBI.
Keywords: Neuroprotection, Behavioral Function, Secondary Injury, Therapeutics/Drug Discovery
INCREASED LEVELS OF OSTEOPONTIN IN CHILDREN WITH SUBDURAL HEMATOMAS DUE TO ABUSIVE HEAD TRAUMA
1Children's Healthcare of Atlanta, Atlanta GA, United States, 2Emory University, Atlanta GA, United States
Keywords: Biomarker, Pediatric
MUSIC AS A NOVEL AND NON‐INVASIVE REHABILITATIVE PARADIGM TO PROMOTE MOTOR, AFFECT, AND COGNITIVE RECOVERY AFTER EXPERIMENTAL TRAUMATIC BRAIN INJURY
1Center for Neuroscience, University of Pittsburgh, Pittsburgh PA, United States, 2Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh PA, United States, 3Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh PA, United States, 4Pediatric Critical Care Medicine, University of Pittsburgh, Pittsburgh PA, United States
Keywords: Rehabilitation, Behavioral Function, Cognition/Learning/Memory, Inflammation/Immune Function
TRAUMATIC INJURY EXACERBATES NEUROPATHOLOGY IN C9ORF72 ALS MOTOR NEURONS
1Northwestern University, Chicago IL, United States, 2University of Illinois at Chicago, Chicago IL, United States
Epidemiological studies reveal an increased correlation between traumatic injury and amyotrophic lateral sclerosis (ALS). Additionally, trauma has been linked to mislocalization of TAR DNA binding protein 43 (TDP‐43), a major pathological feature of multiple neurodegenerative diseases. However, controlled models of trauma are limited and have not extensively characterized this relationship. In this work, we aim to investigate trauma within the scope of ALS using a highly reproducible system designed to study motor neurons derived from human induced pluripotent stem cells (iPSCs). We find that ALS motor neurons have increased susceptibility to severe trauma. Trauma induces extended TDP‐43 mislocalization in ALS motor neurons, whereas only a brief mislocalization is observed in isogenic controls. This results in increased missplicing of downstream RNA‐regulated targets in ALS motor neurons. RNA‐seq results show that differentially expressed genes have opposing patterns in ALS versus isogenic control motor neurons. Trauma induces differential responses in nucleocytoplasmic transport in ALS motor neurons, with a delay in FGNUP response and reduced RANGAP1 staining when compared to isogenic controls. Furthermore, multiple injuries extend TDP‐43 mislocalization. C9orf72 repeat expansion, the most prominent ALS mutation that is also present in frontotemporal dementia (FTD), displays increased neuropathology as a result of trauma. Toxic RNA foci are increased following trauma. Treatment with antisense oligonucleotides (ASOs) targeting the C9orf72 repeat expansion are capable of preventing the increase in RNA foci. Taken together, our results characterize the role trauma plays in enhancing neurodegenerative disease pathology and explore ASOs as a possible preventative therapy for C9orf72 ALS.
Keywords: Neurodegeneration, Axonal Injury, Concussion/mTBI, Neuropathology
PERIPHERAL‐DERIVED IMMUNE CELLS CONTRIBUTE TO THE REMODELING OF PIAL COLLATERAL VESSELS FOLLOWING ISCHEMIC STROKE
1Department of Biomedical Sciences and Pathobiology, Blacksburg VA, United States, 2VA‐MD College of Veterinary Medicine, Blacksburg VA, United States, 3Molecular and Cellular Biology Program, Blacksburg VA, United States, 4Virginia Tech, Blacksburg VA, United States
Stroke is a leading cause of neurological morbidity and mortality in the United States. Approximately 85% of which are categorized as ischemic resulting from embolic middle cerebral artery (MCA) occlusion in the pial surface of the brain. Remodeling of pial collateral vessels (arteriogenesis) is important to enhance retrograde reperfusion of cerebral blood flow, through anterior cerebral artery, into the ischemic penumbra and reduce tissue damage. Increased fluid shear stress triggers arteriogenesis, leading to the activation of endothelium and subsequent recruitment of peripheral‐derived immune (PDI) cells, which promotes the outward growth of collateral vessels. Currently, our studies indicate that EphA4 receptor tyrosine kinase serves as a crucial negative regulator of arteriogenesis in ischemic stroke. The objective of current study is to explore the role of EphA4 in regulating PDI cell‐mediated pial collateral remodeling in a mouse model of permanent middle cerebral artery occlusion (pMCAO). EphA4 bone marrow chimeric knockout (KOBMCs) and wild‐type mice (WTBMCs) were sacrificed 1d post pMCAO. Vessel painted whole brains were harvested for immuno‐histological analysis. Flow cytometry was used to analyze circulating immune cell phenotype dynamics. Rotarod test was performed to assess behavioral recovery. Our initial findings show that PDI‐specific EphA4 negatively regulates arteriogenesis and influences PDI recruitment and function to limit pial collateral remodeling, and tissue perseveration following pMCAO. Overall, our studies will give an insightful understanding of PDI‐specific EphA4 contributes to the neuroinflammatory milieu during pial collateral remodeling.
Keywords: Neuroprotection, Hypoxia/Ischemia, Vascular, Inflammation/Immune Function
LIPIDOME ALTERATIONS IN MILD TRAUMATIC BRAIN INJURY MAPPED USING ULTRAHIGH RESOLUTION MASS SPECTROMETRY IMAGING
1Georgia Institute Of Technology, Atlanta GA, United States, 2Emory University, Atlanta GA, United States
Traumatic Brain Injury (TBI) is a complex disease caused by an impact to the head that alters normal brain function and causes physical, emotional and cognitive disabilities. Lipid biomarkers have the potential to determine TBI severity, to track disease progression, and to aid in treatment decisions. A non‐targeted spatial metabolomics workflow utilizing ultrahigh resolution mass spectrometry imaging (MSI) was developed to determine and localize brain lipid changes in rats following closed head impact. Male Sprague‐Dawley rats were subjected to three impacts (2 min interval; 5 m/s; 5mm, 2mm, and 2mm head displacement; n = 6) to the dorsal head surface using a modified controlled cortical impact device, with a silicone‐padded piston to model repetitive mild TBI, or sham conditions (n = 6). Rats were sacrificed 72 hours post injury, the brains were extracted, flash frozen and sectioned sagittally at 12um. Averaged mass spectra across the 24 imaged sections showed that the highest abundance species were in the 700‐850 m/z range and included phosphatidylcholines, sphingomyelins, phosphatidylethanolamines and phosphatidylglycerols. Principal Component Analysis (PCA) biplots from a control and injured brain demonstrated noteworthy clustering and separation of the control and injured data. A fold change analysis using two replicates of the frontoparietal cortex from three control and three injured brains identified 70 ions that decreased in abundance, and 26 ions that increased in abundance by at least two‐fold in injured brains. Analysis is ongoing, however these results suggest that ultrahigh resolution MSI is a promising method to detect and localize brain lipid alterations following TBI. Support: R01NS101909
Keywords: Biomarker, Imaging, Concussion/mTBI
CONTROLLED CORTICAL IMPACT INDUCES CELL TYPE‐SPECIFIC CHANGES IN BRAIN METABOLISM THAT CONTRIBUTE TO GABAERGIC INTERNEURON LOSS
Sadi Quinones1, Dr. Mike McConnell1, Dr, Michael Whalen1, Dr Joshy George1, Dr Parveen Kumar1, Mary Sommer1, Sammi Bottom‐Tanzer1, Moritz Armbruster1, Julia Schnipper1, Matt Gentry1, Jessica Macedo1, Ramon Sun1,
1Tufts University, Boston MA, United States
Complex and interrelated changes in synaptic transmission, neuronal activity, metabolism, and vascular perfusion occur after TBI. In addition, diverse neuronal and glial cell types undergo heterogeneous changes after injury. To develop novel therapeutics, we need a robust understanding of the diversity of cellular responses to TBI. Human and animal data shows that TBI increases excitatory glutamate signaling. Strategies to reduce glutamate levels have therapeutic promise, as prolonged elevation of brain glutamate after TBI is associated with poor clinical outcomes. Beyond its role as a neurotransmitter, glutamate can serve as a metabolic substrate. Can excess glutamate present following injury be catabolized as a metabolic fuel, both reducing glutamate excitotoxity and restoring metabolic homeostasis? Our data suggest that in vivo treatment with the glycolytic inhibitor 2‐deoxyglucose (2‐DG) in the days after TBI inhibits glutamatergic neuronal activity and reduces glutamate levels. Excitingly, preliminary data suggest in vivo 2‐DG treatment increases the expression of glutamate dehydrogenase (Glud1), which catabolizes glutamate for use in the TCA cycle. 2‐DG upregulation of Glud1 would provide a novel pathway by which injury‐induced increases in glutamate could be harnessed to provide metabolic support after TBI. Here, we will test the hypothesis that in vivo inhibition of glycolysis after TBI reduces glutamate levels by promoting the catabolism of glutamate via upregulation of Glud1. To test our hypothesis, we will use the controlled cortical impact (CCI) model of moderate contusional TBI, combined with electrophysiology, in vivo and in vitro neurotransmitter imaging, single nucleus RNA sequencing (snRNAseq), RNAScope, and advanced metabolomics.
Keywords: Excitotoxicity, Astrocyte, Neurotransmitter, Epilepsy/Seizure, Gene Expression, Electrophysiology, Metabolism/Energetics
MYELOPEROXIDASE PARTICIPATES IN THE REGULATION OF INFLAMMATORY RESPONSES TO CONTROLLED CORTICAL IMPACT BY GENERATING NON‐CANONICAL PHOSPHOLIPID SIGNALS
1Children's Neuroscience Institute, University of Pittsburgh, Pittsburgh PA, United States, 2Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh Medical Center, Pittsburgh PA, United States, 3Department of Environmental and Occupational Health and Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh PA, United States, 4Interdisciplinary Neuroscience PhD Program, Ankara University, Ankara, Turkey
Lysophospholipids (LPLs) are known as pivotal signaling lipids acting as regulators of inflammation. They are canonically generated via phospholipase A‐driven hydrolysis of membrane phospholipids (PLs) but also via a non‐canonical pathway ‐ acting on plasmalogen phospholipids ‐ by myeloperoxidase (MPO). Unlike phospholipases A1 and A2 which attack sn‐1 and sn‐2 positions in PLs, MPO reacts with vinyl‐ether bond at the sn‐1 position of plasmalogens and generates 2‐sn‐polyunsaturated Lyso‐PLs (2‐sn‐PUFA‐LPLs) which may act via G‐coupled‐receptors in the brain after TBI. To explore the effects of the MPO‐driven mechanisms, wild type (wt) and MPO knock‐out (KO) mice (8‐12 wk) underwent CCI (5m/sec velocity, 1.2mm depth, n = 5/group). The enzymatic activity was measured in pericontusional area at different time points and liquid chromatography‐mass‐spectrometry (LC‐MS/MS) was performed to characterize the phospholipidome. We found that CCI caused accumulation of LPLs formed via canonical PLA2‐catalyzed reaction(s) in the brain of both wt and MPO‐KO mice. These LPL species were identified as 1‐sn‐16:0‐2‐sn‐0:0‐LPE, 1‐sn‐18:0‐2‐sn‐0:0‐LPE, 1‐sn‐18:1‐2‐sn‐0:0‐LPE, 1‐sn‐16:0‐2‐sn‐0:0‐LPC and 1‐sn‐18:0‐2‐sn‐0:0‐LPC. We also discovered the PUFA‐LPL produced via a non‐canonical MPO driven hydrolysis reactions of phospholipid plasmalogens pathway in the brain of wt mice. They were represented by 1‐sn‐0:0‐2‐sn‐20:4‐LPE, 1‐sn‐0:0‐2‐sn‐22:4‐LPE and 1‐sn‐0:0‐2‐sn‐20:4‐LPC. No increase in the contents of PUFA‐LPL was detected in MPO‐KO mice. This study demonstrates for the first‐time the presence of non‐canonically MPO‐generated PUFA‐LPLs in the brain of CCI exposed mice. Given the high susceptibility of PUFA‐LPL to enzymatic and non‐enzymatic oxygenation reaction, their pathogenic role and mechanisms of action as regulators of inflammatory responses should be further investigated.
Keywords: Neurotoxicity, Concussion/mTBI, Inflammation/Immune Function, Free Radicals
LIFESPAN DIFFUSION MAGNETIC RESONANCE IMAGING IN MALE MICE REVEALS PROGRESSIVE CORPUS CALLOSUM ABNORMALITIES FOLLOWING JUVENILE CONCUSSION
1University Of California, Irvine, Irvine CA, United States, 2Division of Physiology‐School of Medicine, Loma Linda University, Loma Linda CA, United States, 3Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/Université de Bordeaux, Bordeaux, France
We previously reported early (<30 days) modifications to white matter (WM) composition on both neuroimaging and histological measures following juvenile concussions (Rodriguez‐Grande et al 2018). Diffusion tensor magnetic resonance imaging (DTI) has demonstrated sensitivity to assessment of WM in brain trauma. DTI can assess the lifespan (1‐18mo) modifications to corpus callosum (CC) and overlying somatosensory cortex (SSC).
C57Bl/6 mice were exposed to sham (S), Grade 1 (G1, speed 2 m/sec, depth 1mm), or Grade 2 (G2, 3m/sec, 3mm) closed‐head injury using an electromagnetic impactor at postnatal day 17. In vivo high resolution DTI was conducted at 1‐18 months on a 7T scanner (21 directions, b = 2000 mm2/sec). Diffusion metrics such fractional anisotropy (FA), axial (AD), radial (RD), and mean diffusivity (MD) were extracted from CC and SCC.
The ipsilateral CC exhibited increased MD and RD at 18 months in G1/G2 mice relative to shams. G2 showed elevated RD at 12 months but reduced FA at all ages. G2 contralateral CC had reduced FA and increased RD at 18mo. SSC were less predictive than the CC. Data from DTI were confirmed with immunohistochemistry metrics.
Here we report for the first time, lifespan alterations in the WM of male mice after a single juvenile concussion. We show progressive ipsilateral and contralateral CC alterations that were dependent on concussion severity as identified using DTI. We also found decreased learning and memory that was coincident with the DTI metrics. Thus, juvenile concussion patients would benefit from long‐term monitoring of WM.
Keywords: Aging, Imaging, Concussion/mTBI, White Matter
EFFECTS OF CONTROLLED CORTICAL IMPACT ON DENDRITIC ARBORIZATION IN HIPPOCAMPAL CA1 NEURONS AT 1 MONTH POST‐INJURY
1Dept. of Neurological Surgery, University Of Pittsburgh School Of Medicine, Pittsburgh PA, United States, 2VA Pittsburgh Healthcare System, Pittsburgh PA, United States
The effects of synaptic changes following traumatic brain injury (TBI) have been studied as a mechanism for the cognitive impairments observed in the chronic timeframe. Existing literature demonstrates that in the cornu ammonis 1 (CA1) region of the hippocampus, there is an initial loss of synapses that is counteracted by a delayed increase in the number of synapses in the ensuing weeks, a quantitative recovery that is not correlated with functional recovery. To investigate a potential structural feature that impedes functional recovery, this study examined the effect of controlled cortical impact (CCI) on dendritic arborization in the hippocampal CA1 in rats 4 weeks post‐injury. Adult male Sprague‐Dawley rats (4 animals/group, 4‐6 neurons/animal) were randomly divided into CCI (2.6mm, 4m/s) and Sham control groups. Brains were processed for Golgi staining, then imaged on a Nikon confocal microscope and reconstructed into 3‐dimensional computer models using Neurolucida 360. Sholl analysis showed an uptrend in the number of dendritic branching in the surviving neurons in the CCI condition compared to the sham (1 way repeated measures ANOVA, p < 0.053). This difference was driven by an increase in higher‐order branching – i.e. tertiary branching and above (p = 0.009) – and not by lower order branches, i.e. primary (p = 0.506) and secondary (p = 0.305). In conclusion, CCI leads to significant changes in dendritic arborization in CA1 in the chronic time course concurrent with the synaptic and behavioral changes previously observed in this timeframe. Further study into the molecular mechanisms behind this plasticity may provide insight into future therapeutic targets.
Keywords: Secondary Injury, Cognition/Learning/Memory, Synaptic Function, Regeneration & Plasticity
TRAUMATIC BRAIN INJURY INDUCES AN ACUTE INCREASE IN INTESTINAL PERMEABILITY AND SUBACUTE CHANGES TO THE GUT MICROBIOME OF MICE
1University of Kentucky College of Medicine, Lexington KY, United States, 2University of Kentucky Department of Physiology, Lexington KY, United States, 3Spinal Cord and Brain Injury Research Center, Lexington KY, United States, 4University of Kentucky Internal Medicine ‐ Digestive Health, Lexington KY, United States, 5University of Kentucky Department of Immunology & Molecular Genetics, Lexington KY, United States
Traumatic brain injury (TBI) triggers systemic responses beyond the neurovascular and glial changes within the brain that can include gastrointestinal (GI) dysfunction. The gut microbiota are a key regulator of health and disease, and recent findings associate TBI with altered fecal microbial diversity, but little is known about the timeline of these changes and their relation to gut dysfunction or pathology. Examination of hematoxylin/eosin stained intestinal tissue from mice receiving sham or controlled cortical impact (CCI) TBI (n = 3‐8/injury group at 7 timepoints: 4hr‐4wks) revealed no overt damage. To interrogate intestinal permeability, we orally administered FITC‐Dextran (4kda) prior to euthanasia (n = 6‐8/group, 4 timepoints: 4hr‐3d). Quantification of serum fluorescence revealed an increased permeability at 4hr after CCI (p = 0.0067 compared to sham). To determine a timeline of post‐TBI gut microbiome changes, fecal samples were collected prior to and after sham/CCI injury (n = 6‐7/group, 6 timepoints: 1d‐4wk) for 16s gene sequencing. The phylum Verrucamicrobiota was differentially abundant in CCI mice at 1, 2, and 3d postinjury (ANCOM‐BC; q < 0.05). Verrucamicrobiota species increase under hypoxic conditions and promote intestinal wound healing. To assess GI hypoxia after CCI, pimonidazole‐HCl was administered prior to euthanasia to label hypoxic tissue. Preliminary evidence suggests increased hypoxia at 1 and 3d after CCI. Species within Verrucamicrobiota reside in and regulate the intestinal mucous layer. We found no difference between injury groups when quantifying mucin‐producing goblet cells. Our findings suggest an acute GI disturbance and an increase of beneficial bacteria suggesting a potential compensatory response to systemic stress after TBI.
Keywords: Secondary Injury, Endocrine, Hypoxia/Ischemia, Inflammation/Immune Function, Informatics
SHORT‐CHAIN FATTY ACIDS RESCUE NEUROGENESIS AND FEAR MEMORY IMPAIRED BY GUT MICROBIAL DYSBIOSIS AFTER TBI
1Washington University In St Louis, St Louis MO, United States
Short‐chain fatty acids (SCFAs) are gut‐derived metabolites that are speculated to have a key role in microbiota–gut–brain axis. In our previous report, we demonstrated that antibiotic‐induced gut microbial dysbiosis (AGMD) after traumatic brain injury (TBI) reduces hippocampal neurogenesis and modulates the neuroinflammatory response. In light of these data, we now hypothesize that SCFAs may mediate gut microbiota modulation of TBI. We measured SCFAs concentration in the stool and plasma in antibiotic‐treated and control animals 7 days after controlled cortical impact (CCI) or sham surgery observing a significant reduction in the concentration of SCFAs in stool and plasma in antibiotic‐treated mice. Male and female mice underwent CCI and were then randomized to antibiotics in drinking water or control with or without SCFAs supplementation (25 mM sodium propionate, 40 mM sodium butyrate and 67.5 mM sodium acetate in drinking water) for 1 week. Flow cytometry of brain, blood and gut 7 days after injury revealed a reversal of the T cell response associated with AGMD in SCFA antibiotic‐treated mice. Mice exposed to antibiotics and supplemented with SCFAs also had increased hippocampal neurogenesis and more ramified microglia compared with mice given antibiotics alone. Because antibiotic‐induced changes in gut microbiota persist after discontinuation of antibiotics, we continued SCFA supplementation for 3 weeks and performed fear conditioning 3 months post‐injury. SCFA antibiotic‐treated mice had improved contextual fear memory recall compared with antibiotic‐treated mice. These data suggest SCFAs as an important mechanistic link between the gut microbiota and the traumatically injured brain.
Keywords: Behavioral Function, Microglia, Inflammation/Immune Function, Neurogenesis
PAIN OUTCOMES 3 MONTHS AFTER ADOLESCENT TRAUMATIC BRAIN INJURY
1Harborview Injury Prevention and Research Center, Seattle WA, United States
Keywords: Pediatric, Concussion/mTBI, Pain
ASSOCIATION OF CRANIOTOMY, DECOMPRESSIVE HEMICRANIECTOMY, AND EXTERNAL VENTRICULAR DRAIN (EVD) PLACEMENT WITH PATIENT MORTALITY AND 6‐MONTH FUNCTIONAL OUTCOME FOLLOWING MODERATE TO SEVERE TBI: SECONDARY ANALYSIS OF THE PROTECTIII DATASET
1Dept. of Neurosurgery, Brown University, Providence RI, United States, 2Dept. of Emergency Medicine, Brown University, Providence RI, United States, 3Dept. of Neurosurgery, University of Florida, Gainesville GA, United States, 4Dept. of Information Systems and Operation Management, University of Florida, Gainesville GA, United States, 5Dept. of Biostatistics, Medical University of South Carolina, Charleston SC, United States, 6Dept. of Emergency Medicine, Emory University, Atlanta GA, United States, 7Dept. of Radiology, University of Florida, Gainesville GA, United States, 8Dept. of Health Outcomes & Biomedical Informatics, University of Florida, Gainesville GA, United States, 9Dept. of Emergency Medicine, Virginia Commonwealth University, Richmond VA, United States
Keywords: Imaging, Monitoring, Intracranial Pressure, Neurocritical Care
EFFICACY OF KETONE ESTER DIET IN IMPROVING OUTCOME AFTER BLAST‐INDUCED TRAUMATIC BRAIN INJURY
1Parsons Corporation, Houston TX, United States, 2Henry M Jackson Foundation, Bethesda MD, United States, 3Naval Medical Research Center, Silver Spring MD, United States
The ketogenic diet has shown therapeutic promise for managing neuropathological conditions and treating impact traumatic brain injury (TBI). To date there has been no assessment of its potential benefits in blast‐induced TBI (bTBI), which is a prevalent concern in the military. This study examined the therapeutic potential of artificially induced ketogenesis using a ketone ester (KE) after bTBI. Rats were trained on motor function and cognitive tests and blood samples were analyzed for baseline glucose and ketone levels. Anesthetized rats were exposed to repetitive high intensity blast (or sham) conditions followed immediately by conditioning on KE diet or standard diet for fourteen days, during which blood ketone and glucose levels were analyzed; and the animals were subsequently evaluated for deficits in motor coordination, cognition, and oxidative stress. Within one day, KE treated animals showed an increase in ketone levels with no significant changes to glucose levels indicative of animals being in the state of ketogenesis. KE treated rats showed a significant increase in exploratory behaviors measured via Y‐maze, but no significant changes in motor coordination or cognition. Blast exposures led to a trend towards increase in oxidative stress as seen by elevated reactive oxygen species and 3‐nitrotyrosine in the frontal cortex. KE treatment resulted in a significant increase in total antioxidant capacity in frontal cortex and hippocampus under both sham and blast conditions and a reduction in blast‐induced increase in 3‐nitrotyrosine. These results suggest that post‐blast treatment with KE can potentially ameliorate blast‐induced deficits and improve outcome.
Keywords: Neuroprotection, Behavioral Function, Secondary Injury, Cognition/Learning/Memory, Blast, Concussion/mTBI, Nutrition, Metabolism/Energetics, Free Radicals
NEIGHBORHOOD DISADVANTAGE AND ITS EFFECTS ON POSTTRAUMATIC STRESS SYMPTOMS AFTER MILD TRAUMATIC BRAIN INJURY
1Medical College Of Wisconsin, Milwaukee WI, United States
Mild traumatic brain injuries (mTBI) affect people across the globe, though individual recovery can vary greatly within localized populations. Despite the name suggesting a lower‐severity injury, mTBI and the circumstances that lead to them may cause long‐lasting physical and mental effects. Previous work has found factors such as socioeconomic position (SEP), gender, and race to predict mTBI recovery, but deeper understanding of the impact of social‐ecological factors on recovery is lacking. Recently, neighborhood disadvantage has been found to be a unique contextual factor predicting diverse health outcomes. Our goal was to test the hypothesis that neighborhood disadvantage—measured using the Area Deprivation Index (ADI)—predicts higher severity of posttraumatic stress symptoms after mTBI. Patients (n = 101) were prospectively enrolled from three level 1 trauma center within 24‐hours of injury and assessed with the posttraumatic stress disorder for DSM‐5 symptom checklist (PCL‐5) at 2‐weeks, 3‐months, and 6‐months post‐injury. Linear mixed effects (LME) modeling revealed that higher ADI predicted higher PCL‐5 symptoms across time (ADI main effect p < .001; ADI x visit, p = .241). Importantly, ADI remained a significant predictor of PCL‐5 symptoms (Estimate = 0.31, SE = .06, p < .001) after controlling for demographics (i.e., race, gender), individual SES (i.e., household income, insurance type), and injury variables (injury cause, acute injury characteristics). The effect neighborhood disadvantage has on PTSD symptoms suggests more research is needed to evaluate the relationship between the two and how recovery outcomes can be improved within more disadvantaged populations.
Keywords: Post‐Traumatic Stress, Concussion/mTBI
TBI INFLAMMATORY RESPONSE IS MODULATED BY PROBIOTICS THROUGH THE GUT MICROBIOME
1Child Health, University of Arizona COM‐Phoenix, Phoenix AZ, United States, 2Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix AZ, United States, 3Phoenix Veterans Affairs Health Care System, Phoenix AZ, United States
Digestive system dysfunction and infections are common comorbidities in TBI patients. The systemic inflammatory response post‐TBI alters gut barrier structure and function leading to a decrease in gut microbiome diversity. In this way, the gut microbiome could represent a therapeutic target post‐TBI to alleviate digestive system dysfunction and reduce systemic inflammation. We propose the use of a probiotic product post‐TBI to restore the gut microbiome diversity and reduce the inflammatory response.
15 male and 16 female C57BL/6 mice received midline fluid percussion injury and were administered oral daily the Target GB‐X© probiotic during the first 7‐day post‐injury (DPI). Feces were collected daily starting 7 days before injury (DBI) until 7 DPI. Submandibular blood draws (150 μl) were collected at 7 DBI, 1 DPI, 3DPI, and at 7 DPI to measure macrophages, monocytes, and neutrophils by flow cytometry. Estrous cycle was assessed in female mice starting at 14 DBI by vaginal lavage. The animals were euthanized at 7 DPI for brain and gastrointestinal tract collection.
Male and female mice showed a significant decrease in leukocytes (CD45+) and classical monocytes (CD45+CD11b+ Ly6Chigh) at 1 DPI and 3 DPI and a significant increase in neutrophils (CD45+CD11b+Ly6G+) at 3 DPI and 7 DPI. Pro‐inflammatory blood cell populations are an initial indicator of the inflammatory response post‐TBI with quantification according to the treatment (Water vs probiotic) pending. Further sequencing of the fecal samples will reveal the interaction of the gut microbiome with the pro‐inflammatory response post‐TBI and the modulation by the probiotic treatment.
Keywords: Secondary Injury, Inflammation/Immune Function, Nutrition, Metabolism/Energetics
NEUROMODULATION OF AMPK ON INNATE LYMPHOID CELLS AFTER TRAUMATIC BRAIN INJURY
1Augusta University, Augusta GA, United States
Tissue‐resident and antigen‐independent innate lymphoid cells (ILCs) are cytokine‐producing cells which regulate the initiation and resolution of inflammation. Although extensively studied in periphery, their functional relevance and mechanistic regulation in CNS are still poorly unknown after traumatic brain injury (TBI). Herein, we show presence of ILCs within resected dura and elevated proliferation of all ILC subtypes (ILC1, ILC2, ILC3) within cerebrospinal fluid (CSF) of moderate‐to‐severe TBI patients. We further demonstrate increased presence of meninges‐resident ILCs for up to 1 year after experimental TBI. In line with energetic derangements after TBI, loss of the metabolic regulator, AMPK in genetic mice, increased meningeal ILCs expansion, whereas AMPK activation suppressed proinflammatory ILC1/ILC3 and promoted the frequency of IL‐10–expressing ILC2 after TBI. Moreover, intracisternal administration of IL‐33, an ILC2‐stimulating cytokine, activated AMPK, expanded ILC2, and suppressed ILC1 and ILC3 within the meninges of WT and Rag1 –/– mice, but not Rag1 –/– IL2rg –/– mice. Taken together, we provide novel evidence that AMPK acts as a brake on the expansion of proinflammatory CNS‐resident ILC1/ILC3, while activates the anti‐inflammatory ILC2 after brain injury. These findings establish a mechanistic framework whereby immunometabolic modulation of ILCs may direct the specificity, timing, and magnitude of cerebral immunity.
Keywords: Concussion/mTBI, Inflammation/Immune Function, Metabolism/Energetics
USING INSIGHTS FROM GENOMIC PROFILING TO EXPLAIN THE PROGRESSIVE NEURODEGENERATION AFTER EXPERIMENTAL TRAUMATIC BRAIN INJURY
1Augusta University, Augusta GA, United States, 2University of Washington, Seattle WA, United States
Keywords: Neurodegeneration, Gene Expression, Inflammation/Immune Function, Neuropathology, White Matter
BRINGING THE CLINIC INTO THE LAB: AN EVALUATION OF HOW CLINICALLY COMMON DRUGS AND PHYSICAL THERAPY MUSCLE STRETCHING INFLUENCE THE FUNCTIONAL RECOVERY OF RODENTS AFTER SPINAL CORD INJURY
1Interdisciplinary Program in Translational Neuroscience, University of Louisville KY, USA, 2Kentucky Spinal Cord Injury Research Center, University of Louisville KY, USA, 3Department of Physiology, University of Louisville KY, USA, 4Department of Bioengineering, University of Louisville KY, USA, 5Department of Anatomical Sciences and Neurobiology, University of Louisville KY, USA, 6Department of Neurological Surgery, University of Louisville KY, USA
Stretch‐based physical therapy remains a frontline intervention following spinal cord injury (SCI) utilized to combat muscle atrophy, spasticity, and contractures. In addition to rehabilitation and physical therapy, SCI patients receive a barrage of pharmacological treatments to ameliorate acute and/or chronic sequelae such as neuropathic pain and spasticity. However, the effects of many of these drugs on motor/locomotor function after SCI remains unknown, and in some cases, drugs are known be detrimental to functional recovery in animal models. Despite its clinical relevance, numerous studies have shown that clinically modeled hindlimb stretching of rodents significantly impairs locomotor function. Thus, interactions that may be occurring between physical therapy and commonly prescribed drugs after SCI remain unexplored and may reveal novel cellular mechanisms mediating the detrimental effects of stretching. To address these fundamental questions, adult female Sprague‐Dawley rats received a T10 spinal contusion (n = 12). After 4 weeks of recovery, all animals received daily hindlimb stretching for 2 weeks in combination with a pharmacological intervention (acetaminophen, morphine, baclofen, ibuprofen, or saline). Functional recovery was assessed using the Basso, Beattie, and Bresnahan (BBB) Locomotor Recovery Scale, kinematic gait analysis, and tail‐flick sensory assays to assess thermal cutaneous sensitivity. Locomotor analysis revealed that baclofen and ibuprofen appear to partially mitigate the effects of stretching on locomotor function, while opioids may exacerbate the deleterious effects of stretching. These results emphasize the need to further evaluate the combinatory effects of pharmacological and rehabilitative therapies after experimental and clinical SCI. Supported by the DOD (SC170121).
Keywords: Rehabilitation, Behavioral Function, Therapeutics/Drug Discovery, Pain
IMPLICATIONS OF RACE AND SOCIOECONOMIC STATUS ON PEDIATRIC TRAUMATIC BRAIN INJURY SEVERITY AND OUTCOME
1Children's Healthcare of Atlanta, Atlanta GA, United States, 2Emory University, Atlanta GA, United States
presenting to the Emergency Department with mild to severe TBI were analyzed (n = 463) as part of a larger investigation. The sample is majority male (64.1%) and categorized into Caucasians (48.5%), African‐Americans (37.3%), Latinos (10.1%) and Asian/Pacific Islander/Native American (4.2%).
Keywords: Biomarker, Pediatric
ANTIBIOTIC PROPHYLAXIS IN PENETRATING TRAUMATIC BRAIN INJURY: OUTCOMES FORM A SINGLE‐INSTITUTIONAL SERIES AND META‐ANALYSIS OF THE LITERATURE
1The Warren Alpert Medical School of Brown University, Providence RI, United States, 2Department of Neurosurgery, Rhode Island Hospital, Providence RI, United States, 3Department of Infectious Diseases, Rhode Island Hospital, Providence RI, United States
Penetrating traumatic brain injury (pTBI) is a medical emergency with high mortality. Surviving patients face infection risk stemming from foreign body transgression into the CNS. Research regarding the use of antibiotic prophylaxis to pTBI patients is outdated and contradictory. We performed a MEDLINE literature review and analyzed a local series to learn whether prophylactic antibiosis can reduce infection risks among pTBI patients.
Our local series contained 21 patients from 2015‐2019 (20 male, 1 female; mean age 32 ± 13 years). The most common mechanisms of injury were cranial gunshot wounds. 17 patients received prophylactic antibiotics (regimen range: 1 to >30 days) and 4 did not. Among those receiving antibiotics, 7 received cefazolin alone while 10 received broad spectrum antibiotics. 4 patients (19%) developed CNS infections (3 intraparenchymal brain abscesses, 1 meningitis), with 2 requiring surgical intervention. 2/4 patients (50%) who did not receive prophylactic antibiotics developed CNS infections, compared to 2/17 (12%) who received prophylactic antibiotics. Of the 4 patients who developed intracranial infections, all speciated at least one gram‐positive organism and 1/3 speciated a gram‐negative organism. In the literature, we identified 330 cases. 216/330 (65%) cases received prophylactic antibiotics and 114 did not. Among patients who received antibiotics, 38 (17%) developed an infection. Among patients who did not, 23 (20%) developed an infection (Fisher's exact test, p = .55). While the literature suggests no benefit concerning prophylactic antibiosis, our institutional series indicates that pTBI carries a risk of infection and prophylactic antibiotics may decrease risk of this outcome.
Keywords: Ballistic Injury, Inflammation/Immune Function, Neurocritical Care
SOCIAL INTEGRATION AND ITS RELATIONSHIP WITH COGNITIVE FUNCTION IN TRAUMATIC BRAIN INJURY: A SCOPING REVIEW
1University Of Washington, Seattle WA, United States
Keywords: Rehabilitation, Behavioral Function, Cognition/Learning/Memory, Concussion/mTBI
IMPACT OF BLAST EXPOSURE ON CIRCADIAN MELATONIN RHYTHM AND ITS IMPLICATIONS IN BLAST‐INDUCED SLEEP DISRUPTIONS
1Blast Induced Neurotrauma Branch, Walter Reed Army Institute of Research, Silver Spring MD, United States
Sleep‐wake disturbances are frequently reported after blast‐induced neurotrauma. However, the molecular signaling mechanisms underlying these sleep disturbances are less studied and hence efficacious treatments are lacking. We examined the effects of single and tightly coupled repeated blast exposure on melatonin synthesis pathway in the pineal gland of rats. An advanced blast simulator was used to expose Sprague Dawley rats to single and repeated blasts. Rats were euthanized at 6 hours, 24 hours or 1 month post‐blasts. Expression of genes involved in melatonin synthesis were measured in the pineal glands using quantitative real‐time PCR. Plasma and cerebrospinal fluid melatonin levels were quantified utilizing a commercially available ELISA kit. Single and repeated blast exposures induced statistically significant decreases in MTNR1A, MTNR1B, AANAT and ASMT mRNAs along with an upregulation of TPH2 mRNA in the pineal glands collected at night at all three time point's post‐blasts. No significant changes in any of the genes examined were seen in the pineal glands of animals euthanized in the morning. Plasma and cerebrospinal fluid melatonin levels were correspondingly decreased in the rats euthanized in darkness during the night at 24 hours and at one month after the blast exposure with no significant changes noted in rats euthanized in morning at two time points after blast exposure. Downregulation of genes involved in melatonin synthesis in the pineal gland were noted in blast exposed rats, indicating that disruption of circadian regulation of melatonin synthesis occurs after blast exposure, possibly contributing to sleep disruptions commonly reported in blast victims.
Keywords: Sleep, Blast, Cerebrospinal Fluid, Gene Expression
IMPAIRMENT FOLLOWING BLAST‐INDUCED TRAUMATIC BRAIN INJURY VARIES WITH BRAIN SIZE
1University of Pennsylvania, Philadelphia PA, United States
Blast‐induced traumatic brain injury (bTBI) is a common cause of traumatic brain injury (TBI) within the military population. Although blast exposure is frequently studied in murine models, genetic predisposition to bTBI has not been studied directly, and different mouse strains may show unique responses to blast damage. In this study, we compared the effects of bTBI in six strains of mice (A/J, 129S1/SvlmJ, NOD/LtJ, NZO/HILtJ, C57BL/6, and Ast/EiJ), which encompass over 90% of the genetic variation in commonly used laboratory mice. We exposed each mouse to a shock wave at a pressure of 300 kPa. Immediately following injury, we recorded apnea and righting time. We survived 12 mice from each strain to examine gross brain pathology at 2 different timepoints: 30 min or 8 days post‐blast. All strains had survival rates of 100%, except Ast/EiJ, which had a survival rate of 56.3%. At the same blast exposure level, righting time was moderately correlated with brain mass (y = ‐649.1*x + 493.1, linear regression, p = 0.098), indicating shorter righting times are more likely in larger brains. Righting time also correlates with body weight (y = ‐3.796*x + 270.5, linear regression, p = 0.034), suggesting that individual mice or entire genetic strains with lower body weights had longer righting times, and therefore may suffer greater neurological impairment from bTBI. Future studies will examine potential genetic predispositions and compare pathology across all six strains.
Keywords: Blast, Concussion/mTBI
BRAIN AND SERUM LIPIDOME ALTERATIONS AFTER MILD TRAUMATIC BRAIN INJURY
1Georgia Institute Of Technology And Emory University, Atlanta GA, United States, 2School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta GA, United States , 3Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta GA, United States
Mild traumatic brain injury (mTBI) is diagnostically challenging due to the heterogeneity. TBI causes membrane damage and altered lipid metabolism, therefore, we investigated the overlap of brain and serum lipid changes after closed head TBI. Male (n = 10) and female (n = 16) rats received single impact (smTBI) (n = 8) (5 m/s, 5 mm head displacement), repetitive impacts (rmTBI) (n = 8) (5 m/s, 2 min interval, 5, 2, 2mm displacements), or sham conditions (n = 10). Righting reflex was measured immediately post‐impact and brain and serum samples were analyzed at 24 hours post‐injury by untargeted ultra‐performance liquid chromatography mass spectrometry (UPLC‐MS). Repetitive mTBI rats took significantly longer time‐to‐right than sham (p < 0.05). UPLC‐MS yielded a total of 14,119 and 14,909 total MS features in serum and brain, respectively. Principal component analysis (PCA) of serum showed a separation of sex along PC1, however, there is prominent overlap between male and female brain features. There were 251 tentatively identified features that overlapped between serum and brain. A potential yin‐yang mechanism was evident between the lipid subclasses diacylglycerides, ceramides, and sphingomyelin for rmTBI vs sham, and between diacylglycerides and carnitines for smTBI and sham (increase in serum, decrease in brain). Collectively, the results from this study show overlapping lipids in the brain and serum compartments, suggesting that brain lipid changes may be reflected in the serum, but that the relationship is likely complex and/or reflect independent changes. Understanding TBI‐related lipid dysregulation may lead to novel biomarker candidates, as well as targeted treatment strategies… Support: R01NS101909, 2T32GM008433‐26, DGE‐1650044
Keywords: Biomarker, Concussion/mTBI, Diagnostics
INTERPRETATION OF PEDAL REACTION FORCES IN A RAT MODEL OF MOTORIZED CYCLING
1University Of Louisville, Louisville KY, United States
Passive leg cycling is often utilized with human patients with limited lower‐limb function, despite negligible or inconsistent cardiovascular benefits. Passive hindlimb cycling (PHLC) in rodent models of SCI, however, has been shown to improve multiple indices of cardiac function. One potential mechanism to explain this discrepancy is increased return of peripheral blood to the heart through spinal reflex activation of hindlimb muscles in the rodent model. We hypothesized that the stretch reflex is activated during PHLC, and that muscle activation (and resultant pedal reaction forces) will be cycle period and crank length dependent. To test these hypotheses, we developed a motorized cycle that incorporates a force sensor synchronized to hindlimb kinematics. Our previous studies demonstrated a low frequency component of the pedal force associated with cycle period and pedal crank length, while a high frequency component was associated with spasticity. To differentiate between these components of pedal force, we created a frequency‐domain method for separating forces developed with the motion of the pedal and the remaining high‐frequency forces. Preliminary results from rats with T2, 35g‐cm contusion injuries (n = 5) suggest that the low frequency component of the pedal reaction force increases for cycling cadences ranging from 30 RPM to 60 RPM and are crank‐length dependent. Conversely, high frequency component of the pedal force was larger for movement frequencies below 30 RPM while the limb is in extension. Our results suggest that forces generated during PHLC may be modulated by adjusting straightforward parameters such as limb position, cycling cadence and crank length.
Keywords: Rehabilitation, Exercise
MILD REPETITIVE TRAUMATIC BRAIN INJURY INDUCES CHANGE IN MICROGLIAL MORPHOLOGY
1Georgia Institute of Technology, Atlanta GA, United States
Neuronflammation associated with mild traumatic brain injury (mTBI) is modulated by resident microglia. Factors that promote microglial activation into pro‐ and anti‐inflammatory states after mTBI are not fully understood. The goal of this study was to analyze microglial morphology after single mTBI (smTBI) and repetitive mTBI (rmTBI). Male and female Fischer rats received single (n = 8) or double (24‐hour interval, n = 8) closed head impact with a pneumatic piston (5 m/s, 5 mm head displacement) or sham conditions (n = 8). Brains were collected 24 hours and 1 week post injury and sectioned (30μm). Cortical microglia were counted in 4 sections/brain (IHC for Iba1; 1:500, Wako 019‐19741) and morphological analysis was done using a custom MATLAB program and principal component analysis for features such as cell volume and branch closeness. At 24 hours post injury, cell counts increased in both smTBI ( p = 0.03) and rmTBI (p = 0.0001) relative to sham . There was no significant difference between sham and smTBI at 1 week, however, cell count significantly differed between sham and rmTBI (p = 0.002). PCA1 score shows microglia with pro‐inflammatory characteristics at 24 hours post smTBI and rmTBI. At 1 week, the pro‐inflammatory morphology was attenuated in the smTBI group; however, the rmTBI group appeared to display an anti‐inflammatory morphology. These results indicate microglia immediately activate towards the pro‐inflammatory state following both smTBI and rmTBI but may change towards an anti‐inflammatory state. Future studies will further investigate the potential shift in microglial function after smTBI and rmTBI and analyze sex differences. Supported by R21 NS091832
Keywords: Neuroprotection, Microglia, Concussion/mTBI, Inflammation/Immune Function
DIAGNOSTIC UTILITY OF GFAP BEYOND 24 HOURS OF ACUTE TRAUMATIC BRAIN INJURY: A TRACK‐TBI STUDY
1University Of Pittsburgh, Dept of Neurosurgery, Pittsburgh PA, United States, 2University of Michigan, Dept of Emergency Medicine, Ann Arbor MI, United States, 3University of Pennsylvania, Dept of Neurology, Philadelphia PA, United States, 4University of California, San Francisco, San Francisco CA, United States, 5University of Florida, McKnight Brain Institute, Gainesville GA, United States, 6University of California, San Diego, San Diego CA, United States
Keywords: Biomarker, Imaging, Concussion/mTBI, Diagnostics
TREATING ACUTE SPINAL CORD PATIENTS WITH A SPINAL CORD PERFUSION PRESSURE MANAGEMENT PROTOCOL
1University Of Pittsburgh, Pittsburgh PA, United States, 2Vancouver Spine Surgery Institute, Vancouver, Canada
Keywords: Cerebrospinal Fluid, Edema, Monitoring, Inflammation/Immune Function
ADAPTIVE IMMUNE TARGETING AMELIORATES DEPRESSION AND COGNITIVE IMPAIRMENT IN A MOUSE MODEL OF ALZHEIMER'S DISEASE FOLLOWING TBI
1Texas A&m Health Science Center, Bryan TX, United States
Traumatic brain injury (TBI) is a substantial risk factor for developing Alzheimer's disease (AD). Evidence supports the idea that TBI induces immune and neuropathological signatures associated with AD. While inflammation and neuroinflammation are considered pathological hallmarks of AD, it is unknown how inflammation after TBI might facilitate or accelerate AD. We previously identified a pathogenic role for rapid post‐TBI B cell expansion. B cells are an essential element in the transition to an adaptive immune response and evidence supports a pathogenic role for B cells in AD. We previously identified and synthesized a competitive antagonist peptide (CAP) to class II invariant peptide (CLIP) in the MHC‐binding groove of antigen presenting cells, including B cells. We hypothesized that CAP administration after TBI in 5xFAD mice would inhibit TBI‐induced AD pathogenesis. We examined functional outcomes related to depression and cognition. Depression‐associated behaviors were assessed because depression occurs in >50% of TBI patients and is a major predictor of AD. Animals underwent depression battery testing one‐week post‐injury, and then monthly for 4 additional months, followed by cognitive testing 5 months post‐injury. Plaques were examined postmortem in the hippocampus and neocortex, and TBI was observed to enhance plaque accumulation. TBI induced a progressive depression‐like phenotype that was partially mitigated by CAP. TBI also induced a long‐term deficit in the pattern recognition task, but not in the object location task. These results suggest that TBI induces chronic neurobehavioral dysfunction in 5xFAD mice that is selectively sensitive to antagonizing CLIP in the antigen‐binding groove of MHCII.
Keywords: Aging, Depression, Neurodegeneration, Inflammation/Immune Function
DYNAMIC CHANGES IN LIPID MEDIATORS OF INFLAMMATION ACUTELY FOLLOWING TRAUMATIC BRAIN INJURY: A PROSPECTIVE, OBSERVATIONAL LIPIDOMIC STUDY
1The University of Southern California, Los Angeles CA, United States
Keywords: Biomarker, Secondary Injury, Inflammation/Immune Function
ACCELERATED MATURATION AND INTEGRATION OF IMMATURE ADULT BORN GRANULE CELLS AFTER TRAUMATIC BRAIN INJURY
1Rutgers School of Graduate Studies, Newark NJ, United States, 2University of California, Riverside, Riverside CA, United States
Traumatic brain injury (TBI) is associated with altered neurogenesis in the adult neurogenic niche of the hippocampal dentate gyrus. However, how immature adult‐born granule cells (abGCs) generated after trauma impact the circuit and the timeline for their circuit effects are not known. We examined wild‐type or tamoxifen inducible Nestin‐creERT2‐ChR2‐YFP mice subject to sham or moderate concussive fluid percussion injury (FPI) at 8‐10 weeks of age at various time points after injury to determine circuit integration of abGCs. We find an increase in aberrant migration of doublecortin‐positive immature abGCs to the outer 2/3rd's of the granule cell layer at three days post‐injury. Both the number of BrdU labeled cells as well as co‐expression of NeuN, a marker for mature neurons, with BrdU were increased one week after FPI. In whole cell recordings from mature granule cells, optically activating abGCs born after injury consistently evoked monosynaptic excitatory currents in slices from FPI mice as early as one‐week post‐injury but not in SHAM controls. The amplitude of optically‐evoked, abGC‐mediated IPSCs, observed in both SHAM and FPI groups, was significant increase in FPI mice. In‐vivo stimulus evoked LFPs revealed increase in excitability one week after FPI which was selectively suppressed by optical activation of injury‐induced abGCs selectively in FPI mice but not in sham controls. These results identify accelerated maturation and circuit integration of abGCs generated after injury within one week post‐mitosis, much earlier than the normal abGC maturation and integration timeline.
Support NIH R01NS097750 to V. S; NIH 5F31NS110220‐03 to L.C
Keywords: Epilepsy/Seizure, Neurogenesis
TRIGEMINAL NERVE STIMULATION PROTECTS WHITE MATTER FROM SUBARACHNOID HEMORRHAGE THROUGH CGRP PATHWAY
1Elmezzi Graduate School of Molecular Medicine , Manhasset NY, United States, 2Neurosurgery, Zucker School of Medicine at Hofstra/Northwell Health, Manhasset NY, United States
Keywords: Neuroprotection, Secondary Injury, Blood Brain Barrier, Axonal Injury, Cell Death, Hemorrhage, Therapeutics/Drug Discovery, Hypoxia/Ischemia, Inflammation/Immune Function, Cerebral Blood Flow, White Matter
TEMPORAL PATTERNS OF SERUM SODIUM ASSOCIATED WITH MORTALITY IN CHILDREN WITH SEVERE TBI IDENTIFIED USING CLUSTER ANALYSIS
1Department Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh PA, United States, 2Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh PA, United States, 3Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh PA, United States, 4Brain Care Institute, UPMC Children's Hospital of Pittsburgh, Pittsburgh PA, United States, 5Division of Critical Care Medicine, Children's National Medical Center, George Washington University School of Medicine, Washington DC, United States, 6Department of Pediatrics, Division of Health Informatics, UPMC Children's Hospital of Pittsburgh, Pittsburgh PA, United States
Keywords: Pediatric, Intracranial Pressure, Neurocritical Care
MICRORNA BIOMARKERS FOR REPETITIVE BLAST EXPOSURES IN A BREACHER COHORT
1Uniformed Services University Of The Health Sciences, Bethesda MD, United States, 2John Hopkins University School of Nursing, Baltimore MD, United States, 3Naval Medical Research Center, Silver Spring MD, United States
Injuries from single or repetitive blast explosions are a common type of brain trauma in the US military. Professional breachers are exposed to multiple explosive blast events as a part of their training and duty. Evidence suggests that these individuals exhibit impairments which are consistent with neurological outcomes reported with repetitive blast exposure. The aim of this study was to identify blood‐based biomarkers that can differentiate individuals with repetitive blast injury from controls. MicroRNAs (miRNAs) are small non‐coding RNAs of 20‐25 nucleotides in length that regulate gene expression and are considered biomarkers for neurological disease and disorders. This study included serum samples from breachers cohorts (N = 23) and age‐matched controls (N = 16). Analysis of miRNA expression from serum samples was accomplished using TaqMan low‐density array cards. Results show significantly increased expression of six miRNAs in the breacher cohort. A significant down regulation of 19 miRNAs is also observed. The miRNA expression changes are confirmed by digital PCR. Pathway analysis shows that the dysregulated miRNAs are predominantly related to inflammatory pathways, and the downregulated miRNAs may contribute to increased inflammation. In summary, this study identifies miRNA signatures from serum samples from experienced breachers which can be further explored as signature biomarkers for blast‐related neurocognitive impairment.
Keywords: Biomarker, Blast, Concussion/mTBI, Diagnostics
SYNAPTOPODIN AS A POTENTIAL REGULATOR OF AXONAL COLLATERAL SPROUTING
1University Of Louisville, Louisville KY, United States, 2University of Louisville, Department of Anatomical Sciences and Neurobiology, Louisville KY, USA, 3Wolfson Centre for Age‐Related Research, King's College London, London, UK, 4Spark Therapeutics, Philadelphia PA, USA, 5Swiss Federal Institute of Technology (EPFL), Geneva, Switzerland, 6University of New England, Department of Biology, Biddeford ME, United States
Keywords: Biomarker, Genetic Factors, Gene Expression, Imaging, Regeneration & Plasticity
ROLIPRAM DELIVERED BY PGP NANOCARRIER REDUCES SECONDARY INJURY AND ENHANCES MOTOR FUNCTION IN A RAT MODERATE CONTUSION SCI MODEL
1Clemson University, Greenville SC, United States, 2Drexel University, Philadelphia PA, United States
Due to limited intrinsic healing capacity and the absence of effective therapeutic treatment, spinal cord injury (SCI) usually results in permanent loss of motor and sensory function below the level of the lesion. SCI exhibits a complex pathophysiology that presents multiple barriers such as reduction of cAMP, activation of myelin‐associated inhibitors and formation of astrogliosis. Our goal is to develop nanotherapeutics for a combinatorial therapy of rolipram (Rm) and RhoA siRNA (siRhoA) modulating cAMP and RhoA signaling pathways, respectively, using a cationic amphiphilic polymeric nanocarrier, poly (lactide‐co‐glycolide)‐graft‐polyethylenimine (PgP). In this study, we evaluated the effect of Rm loaded PgP (Rm‐PgP) single and repeat treatment via intrathecal catheter on neuroprotection and inflammatory response; motor function recovery; and neuropathic pain in a rat moderate contusion SCI model at 1 week post‐injury (Acute) and 6 weeks post‐injury (Chronic). We observed that Rm‐PgP treated groups had significant cAMP levels restoration and lesion volume reduction at 7 DPI. We also observed that both Rm‐PgP treatment groups significantly increased the neuronal survival by reducing the inflammatory response and reduced astrogliosis formation compared to untreated SCI group. For the motor function recovery, we observed that BBB scores of both Rm‐PgP treatment animals were significantly higher than that of untreated SCI animals from 5 DPI up to 6 weeks. For neuropathic pain, we observed that pain level in both Rm‐PgP treated groups were significantly lower than that in untreated SCI group.
Keywords: Behavioral Function, Secondary Injury, Drug Delivery, Axonal Injury
IMBALANCE OF EVOKED GLUTAMATE AND GAMMA‐AMINOBUTYRIC ACID RELEASE IN THE HIPPOCAMPUS AND COGNITIVE IMPAIRMENT AFTER FLUID PERCUSSION INJURY
1Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh PA, United States, 2Department of Pharmacy & Therapeutics, University of Pittsburgh School of Pharmacy, Pittsburgh PA, United States, 3Center for Clinical Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh PA, United States, 4Department of Neurosurgery, Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh PA, United States
Cognitive impairment from traumatic brain injury (TBI) is a substantial source of morbidity after injury. Impaired cognitive abilities have been well observed both clinically and in animal models after TBI. In a healthy hippocampus, glutamate (excitatory) and GABA (inhibitory) amino acid neurotransmitters release is dictated by a coordinated response integral to hippocampal dependent learning and memory. From within hours to months after TBI, neurotransmitters release imbalances have been associated with neuroexcitoxicity and synaptic dysfunction, that can manifest to chronic post traumatic epilepsy. Simultaneous assessment of these neurotransmitters is informative to understanding these imbalances. We hypothesized that evoked glutamate and GABA release is altered after fluid percussion injury (FPI), thus contributing to cognitive impairment. To test this, male Sprague Dawley rats (SHAM = 9, Lateral FPI = 9) were tested for motor and cognitive function for 2wks after FPI. A microdialysis probe was implanted in the ipsilateral hippocampus. Cerebrospinal Fluid (aCSF) was pumped through the probe. High potassium aCSF was administered to measure evoked release. Microdialysis samples were collected every 20min. Using a novel LC/MS approach, we measured glutamate (50‐1500ng/mL) and GABA (5‐150ng/mL) concentrations simultaneously. Results show that in FPI rats glutamate release was significantly lower (p = 0.05) but GABA release was unchanged as compared to sham. Our findings highlight simultaneous measurements of glutamate and GABA can be implemented and ongoing work is aimed at understanding mechanisms contributing to impaired synaptic function and for testing the efficacy of therapeutic interventions to promote recovery of synaptic function after TBI.
Keywords: Behavioral Function, Neurotransmitter, Cerebrospinal Fluid, Synaptic Function
VAGAL NERVE STIMULATION AS A TREATMENT FOR DYSAUTONOMIA AND BEHAVIORAL DEFICITS FOLLOWING BLAST TBI
1Graduate Program in Neuroscience, University of Washington, Seattle WA, United States, 2Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle WA, United States, 3Department of Pharmacology, University of Washington, Seattle WA, United States, 4Center for the Neurobiology of Addiction, Pain, & Emotion, Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle WA, United States, 5Geriatric Research Education and Clinical Center, Veterans Affairs Puget Sound, Seattle WA, United States, 6Mental Illness Research Educational and Clinical Center, Veterans Affairs Puget Sound, Seattle WA, United States
Mild traumatic brain injuries (mTBI) are one of the leading causes of death and disabilities worldwide and are especially insidious in the military, with up to 25% of OIF/OEF Servicemembers diagnosed with a service‐related mTBI. The majority (∼75%) of these injuries occur as the result of exposure(s) caused by high explosives. Blast mTBI cause inflammation resulting in chronic neurodegenerative pathophysiology and autonomic nervous system dysfunction, which may underlie post‐concussive sensorimotor symptoms (e.g., headaches, dizziness, fatigue, etc.) and behavioral dysfunction (e.g., anxiety, depression, impulsivity, etc.) post‐blast. Vagus nerve stimulation (VNS) is a promising treatment for symptoms related to blast TBI since the vagus nerve serves as a key regulator between the autonomic and central nervous system, has anti‐inflammatory properties and is already approved to treat migraines and depression. Using an established blast overpressure model of blast TBI in mice, male C57Bl/6 mice underwent either 3 blasts (one exposure/day for 3 days) or sham (anesthesia only) exposures and were either treated 1‐hour later with VNS (2‐minute trains, every 15 minutes, for 1 hour) or sham (anesthesia only) stimulation. Behavioral dysfunction was examined acutely following blast and up to 5 months post‐blast. Vital signs and inflammation; as measured through cytokine expression in whole brain and blood serum samples; were analyzed throughout the experiment. These findings demonstrate differences in inflammation following blast and sham exposure and support the therapeutic use of VNS treatment following blast‐induced mTBI. We thank the NIDA Training Grant 2T32DA007278‐26 (BMB) for funding this project.
Keywords: Behavioral Function, Blast, Concussion/mTBI, Therapeutics/Drug Discovery
EFFECTS OF CHRONIC STRESS AND DIET ON OUTCOME FOLLOWING CLOSED HEAD INJURY IN RATS
1Georgia Institute Of Technology, Atlanta GA, United States
Traumatic brain injury (TBI) outcomes can vary based on injury severity, premorbid conditions, and secondary injury manifestation, as well as non‐medical factors. While psychosocial and socioeconomic factors cannot be captured in preclinical TBI models, chronic stressors can be introduced to partially address disparities in outcome. This study models the effect of chronic unpredictable mild stress (CUMS) and Western diet on TBI outcome. Experimental groups consisted of 48 male Sprague Dawley rats randomly assigned to 1 of 8 groups (n = 6/group): 21 days of CUMS or normal handling, balanced or Western diet rat chow, and single closed head impact (5 m/s, 5 mm unrestrained head displacement) or sham conditions. Outcomes included righting time, body weight, and sucrose preference test (SPT). Preliminary results show an increased righting time for injured rats that were both stressed and had Western diet (p < 0.01). Weight tracking showed significant differences between normal diet stressed and unstressed rats at days 15, 17, and 19 (p < 0.05) and days 22, 24, 26 (p < 0.01), suggesting evidence of stress. However, there are no significant differences between Western diet stressed and unstressed groups. SPT showed no differences among groups. Ongoing analyses include elevated plus maze, modified neurological severity score, blood corticosterone, and histopathological markers for neuroinflammation and neuronal and glial changes. We expect that corticosterone and inflammatory markers will increase for the stress and Western diet combination more than either alone. This experimental framework of heterogeneous physiologic stressors may mimic allostatic overload associated with poor TBI outcome. Funding provided by departmental seed funds.
Keywords: Depression, Post‐Traumatic Stress, Concussion/mTBI
THE EFFECT OF HIGH FREQUENCY HEAD IMPACT AND CONTROLLED CORTICAL IMPACT ON SLEEP ARCHITECTURE AND CIRCADIAN RHYTHMS
1Georgetown University, Washington DC, United States
Traumatic brain injury (TBI) is a significant risk factor for the development of chronic sleep impairments, with even a mild TBI causing sleep disturbances in over 25% of patients. Studies show that sleep disruption in animal models of TBI potentiate cognitive impairments, but there are limited in‐depth studies on the impact of TBI on sleep in rodent models of TBI.
Here we characterized and compared sleep architecture and circadian rhythms using two mouse models of TBI – a high frequency head impact (HFHI) model and controlled cortical impact (CCI) model. We found disruptions in diurnal expression of core clock genes in multiple brain regions following both HFHI and CCI. We studied sleep architecture using implantable EEG/EMG telemetry devices, and at 7d post‐injury we found no differences in time spent in wake, NREM, or REM states, or in the bout length of these behavior states. However, we found shifts in sleep microarchitecture during both NREM and REM sleep in CCI mice, but not in HFHI mice. In addition, we report increases in alpha and delta power in HFHI mice during wakefulness, but not in CCI mice.
Our data show that while there is disruption of diurnal circadian rhythm gene expression in the HFHI and CCI models, this does not result in gross changes to sleep architecture. However, both repeat mTBI and severe brain trauma caused distinct and discrete shifts in EEG power bands that indicate distinct EEG patterns after injury, and a disrupted sleep quality in severe brain trauma.
Keywords: Sleep, Gene Expression, Concussion/mTBI
IDENTIFYING BIOMARKERS FOR DIFFERENT SENSORY MODALITIES OF CENTRAL NEUROPATHIC PAIN FOLLOWING SPINAL CORD INJURY
1Rush University Medical Center, Chicago IL, United States
Central neuropathic pain (CNP) commonly develops in patients after spinal cord injury (SCI), causing debilitating symptoms and sensory abnormalities such as allodynia and hyperalgesia. CNP regularly presents itself around a year after the injury, resulting from permanent cellular and anatomical changes from a strong inflammatory response. Previous scientific studies have demonstrated greater efficacy of treatments when delivered preemptively, but there is currently no marker to indicate which individuals are likely to develop CNP. Thus, it is necessary to investigate the physiological processes contributing to sensory changes that develop over time in CNP. Here we assess heart rate, blood pressure, and cytokines as early biomarkers to CNP through changes in allodynia, hyperalgesia and gait. First, we used female Sprague Dawley rats to successfully show repeated assessments over a period of 6 weeks does not alter mean outcomes (p < .001). The tail flick test for hyperalgesia showed elevated heart rate and blood pressure at 7 days post injury (p < .05). The Von Frey test for allodynia did not show any significant changes at acute timepoints for heart rate or blood pressure. The CatWalk analysis did not correlate to blood pressure or heart rate but did show moderate correlation between intensity and allodynia, suggesting altered gait can be used as a measure of mechanical allodynia. We conclude acute elevation in heart rate may predict the development of hyperalgesia, as well as significantly altered gait after SCI as an indicator of allodynia.
Keywords: Biomarker, Pain, Inflammation/Immune Function, Neuropathology
HDAC6 INHIBITION EFFECTIVELY PREVENTS LOSS OF SENSORY NERVE FIBER DENSITY IN BLADDER TISSUE AND IMPROVES BLADDER FUNCTION AFTER CONTUSION SCI IN A MURINE MODEL
1University of Alabama at Birmingham, Birmingham AL, United States
Spinal cord injury (SCI) commonly results in neurogenic lower urinary tract (LUT) dysfunction, including reduced detrusor contractility normally mediated by sensory afferent nerve activity. Histone deacetylase 6 (HDAC6) is a cytoplasmic class II HDAC with specificity for several nonhistone proteins, including the cytoskeleton protein alpha‐tubulin. The objective of this study was to examine changes in bladder wall sensory nerve fiber density after SCI and test the efficacy of histone deacetylase 6 (HDAC6) inhibition in preventing nerve fiber loss and improving functional outcomes. Groups of adult female C57Bl6/J mice underwent midthoracic contusion SCI (75 kdynes). Starting on the day of surgery, mice were administered a daily regimen of an HDAC6 inhibitor (ACY‐1083 or tubacin) or vehicle. One week later, cystometrogram (CMG) testing was performed to assess bladder contractility and bladders were harvested for quantification of PGP 9.5+ nerve fiber profiles. During CMG testing, there was a significant decrease in intercontraction interval with ACY‐1083 (p = 0.0045) and tubacin (p = 0.0089) treatment compared to vehicle that correlated with a significant increase in the number of voiding contractions after ACY‐1083 (p = 0.0319) and tubacin (p = 0.0023) treatment. Both drugs also prevented a significant reduction in bladder nerve fiber profile density compared to vehicle (ACY‐1083 p < 0.0001; tubacin p < 0.0001). In summary, HDAC6 inhibition with ACY‐1083 or tubacin improved LUT functional outcomes and reduced denervation of peripheral sensory axons in bladder tissue. HDAC6 inhibitor isoforms may function as a deacetylase for several nonhistone proteins. However, tubacin specifically alters alpha‐tubulin acetylation status, which is a key regulator of neuronal mitochondrial transport.
Keywords: Behavioral Function, Axonal Injury, Therapeutics/Drug Discovery
METFORMIN ATTENUATES EFFECTOR T‐CELL ACTIVATION AND WHITE MATTER LOSS VIA IMMUNOMETABOLIC REPROGRAMMING AFTER TRAUMATIC BRAIN INJURY
1Augusta University, Augusta GA, United States, 2University of Washington, Seattle WA, United States
Keywords: Secondary Injury, Inflammation/Immune Function, Metabolism/Energetics, White Matter
ALLEVIATION OF IMPULSIVITY AFTER TRAUMATIC BRAIN INJURY VIA HIPPOCAMPAL‐HYPOTHALAMIC CIRCUITRY MANAGEMENT
1Indiana University, Indianapolis IN, United States
TBI causes a wide range of pathological changes in the brain that lead to multiple neurological disorders. To date, these disorders are mostly incurable due to we are unable to link the pathological changes in TBI to specific symptoms. Recent findings and emerging new technologies have identified abundant of function related neural circuitries. This provides an opportunity to bridge the gap between pathologies and functional outcomes after trauma. Moreover, it offers a new approach: we may treat specific disorder by directly target the neural circuitry. Impulsivity is a commonly reported emotional disorder among young TBI patients. We replicated this symptom in a controlled cortical impact (CCI) mouse model of TBI and studied the alteration of impulsivity and related hippocampal‐hypothalamic circuit following trauma. Our data showed that TBI dramatically increased the injured mice impulsivity and significantly damaged hippocampal‐hypothalamic circuit with a remarkable decrease of neuronal activity in ventral hippocampal CA1 (vCA1) and lateral hypothalamic area (LHA), two regions that have been demonstrated to be critical for regulating impulsive activity. Using chemogenetic system DREADD, we manually increased the neuronal activity in vCA1 of TBI mice. The Dreadd infected vCA1 neurons not only projected into LHA, but also enhanced the neuronal activity in LHA. This increase of neuronal activity in LHA may eventually lead to the alleviation of impulsive activity after TBI. Taken together, we hypothesize that the disruption of hippocampal‐hypothalamic circuit is the molecular mechanism underlies impulsivity after TBI and impulsivity may be able to be alleviated via hippocampal‐hypothalamic circuitry management.
Keywords: Behavioral Function
ARE CERVICAL CT SCANS NECESSARY IN ALL INTOXICATED TRAUMA PATIENTS: A RETROSPECTIVE EVALUATION OF PREDICTORS FOR C‐SPINE INJURIES
1Louisiana State University School of Medicine in New Orleans, New Orleans LA, United States, 2University of Miami Miller School of Medicine, Miami FL, United States, 3Louisiana State University School of Medicine in New Orleans, Department of Surgery, New Orleans LA, United States, 4University Medical Center New Orleans LCMC Health, New Orleans LA, United States
Keywords: Imaging, Cervical
ESTABLISH SEVERE ISCHEMIA MODEL BY GERBIL CCA OCCLUSION
1Kangwon National University, Chuncheon, Republic of Korea
Compared to mice or rat ischemia model, CCA occlusion model(UOCCA) of gerbil have advantages of simplicity and reproducibility due to lack of the posterior communicating arteries. Previously we reported 30 min of UOCCA can be used to study mechanisms of infarction and/or regional selective neuronal death/loss. Here we present sever ischemia model by 1h of UOCCA.
Male Mongolian gerbils were obtained at 6 months of age (body weight , 70‐75 g) from the Experimental Animal Center. the gerbils were carried out at left side for 1 hour using nontraumatic aneurysm clips after a midline incision under general anesthesia. After surgery, neurological signs of the animals were observed as a previously reported method for quick evaluation of six neurological signs. For histology in the cerebral cortex, striatum, thalamus and hippocampus at 5 days after UOCCA. We analyzed numbers of F‐J B, NeuN, GFAP, and Iba‐1 positive cells according to our published method.
This study reveals that 1hour of UOCCA induced infarcts in cerebral cortex, striatum, thalamus, and hippocampus depending in relation with ischemic symptoms in gerbils at 5 days after UOCCA. A substantial degree of reactive astrocytes and microglia were found, although numbers of GFAP and/or Iba‐1 immunoreactive cells were different depending on the ischemic regions 5 days after UOCCA.
For developing biomarker, It is most important to establish the mild, moderate and severe brain injury model with reproducibility. We produce the graded brain ischemia model by gerbil.
Keywords: Biomarker, Microglia, Axonal Injury, Vascular, Neuropathology
AGE‐RELATED VASCULAR DYSFUNCTION INCREASES VULNERABILITY TO TRAUMATIC BRAIN INJURY
1Midwestern University, Surprise AZ, United States, 2University of Arizona, College of Medicine, Phoenix AZ, United States, 3Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix AZ, United States
Nearly half of adults in the USA have vascular dysfunction, where numbers increase with age, but few studies link peripheral changes to cerebral, and there is no method to assess contribution of vascular dysfunction to vulnerability of TBI. Vascular dysfunction is a major contributor to this increased risk due to compromised extracellular matrix, vascular wall stiffening and weakening, and endothelial dysregulation. We hypothesize that vascular dysfunction and age contribute to alterations in the aorta, posterior cerebral artery (PCA) and increases in blood‐brain barrier (BBB) permeability, making the brain more vulnerable to mild TBI (mTBI). This study utilized a well‐characterized transgenic mouse model (Fbn1+/‐) that develops vascular dysfunction, including aortic aneurysm, by 6months‐of‐age. In 6M Fbn1+/‐, 6M‐ and 12M‐old C57BL/6 wildtype (WT) mice, aortic pulse wave velocity (PWV), aortic root diameters, PCA blood flow velocity, and BBB permeability were assessed (N = 3‐12). Our data demonstrate that 6M‐old Fbn1+/‐ mice have peripheral vascular dysfunction demonstrated through increased aortic PWV (p < 0.05), and aortic root diameters (p < 0.001), as well as cerebrovascular dysfunction seen through decreased PCA blood flow velocity (p < 0.05), and increased BBB permeability in the hippocampus (p < 0.05) compared to 6M‐old WT, similar to 12M‐old WT. At 24 hours post‐midline fluid percussion injury, Fbn1+/‐ mice demonstrated robust BBB permeability in the hippocampus compared to naive mice. This data supports that peripheral vascular dysfunction can accelerate cerebrovascular aging and vulnerability to mTBI. Furthermore, this data supports the novel utilization of the Fbn1+/‐ mouse model as a model of accelerated vascular aging. Funding‐Valley Research Partnership‐2232011, NIH‐R15HL145646, NIH‐R01NS100793.
Keywords: Aging, Blood Brain Barrier, Concussion/mTBI, Vascular, Cerebral Blood Flow
CHEMOGENETIC ATTENUATION OF NOCICEPTIVE HYPERACTIVITY TO ENHANCE FUNCTIONAL RECOVERY FOLLOWING SPINAL CORD INJURY
1Department of Biology, Texas A&M University, College Station TX, United States, 2Texas A&M Institute for Neuroscience, Texas A&M University, College Station TX, United States
Spinal cord injury (SCI) frequently results in chronic neuropathic pain, for which there are no effective treatment strategies available. Previous work has demonstrated that primary nociceptors residing in the dorsal root ganglion (DRG) become persistently hyperactive after SCI, contributing to the development of chronic sensitization and impairing locomotor recovery. We, therefore, hypothesize that silencing the hyperactivity of pain neurons that occurs early after injury will be advantageous for long‐term sensory and motor functional outcomes. To test this hypothesis, we took advantage of a chemogenetic strategy to selectively silence nociceptors. We found that DREADD expression was almost completely restricted specific to small‐diameter nociceptors. We delivered AAV6‐Gi‐DREADD to lumbar DRG nociceptors through intrasciatic injections 4 weeks before thoracic contusion SCI, activated DREADDs through oral delivery of agonist clozapine‐N‐oxide for 14d post‐injury, and analyzed sensory and motor outcomes for 10 weeks. Through analysis of behavioral assessments, a higher thermal pain threshold and greater hindlimb coordination were observed in subjects that received acute nociceptor silencing, compared to the controls. Together, our findings suggest that nociceptor silencing in the acute phase of SCI may promote beneficial plasticity in the acute phase of injury that affects long‐term functional outcomes. We are currently performing histological assessments on the spinal cord and DRG tissue. The results of this will allow us to determine the anatomical outcome of DREADDs administration and also correlate these outcomes with behavioral responses.
Keywords: Neuroprotection, Behavioral Function, Pain, Regeneration & Plasticity
EFFECTS OF CLOSED HEAD INJURY ON EXTINCTION OF CONDITIONED FEAR IN RATS
1University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
Over 2.8 million people in the United States suffer from concussive brain injury yearly. Unfortunately, individuals are more susceptible to develop fear related disorders after concussion. The influence of concussion on fear regulation can be understood in an animal model using Pavlovian fear conditioning and extinction. In fear conditioning, a subject learns that a neutral stimulus (i.e. auditory tone) predicts an aversive stimulus (i.e. mild foot shock), such that subsequent presentations of the stimulus elicit fear responses. Fear extinction occurs when the previously neutral stimulus that had been presented with an aversive stimulus is repeatedly presented in the absence of the stimulus. In the current study, we evaluated the effects of closed head injury on the extinction of learned fear in rats. We hypothesized that closed head injury impairs fear extinction. To achieve this, adult male Sprague‐Dawley rats underwent fear conditioning, where they learned that an auditory stimulus predicts an unconditioned stimuli (i.e. mild foot shock). Fear was indicated by quantifying freezing behavior, which is defined as a lack of movement except for those related to breathing. Subsequently, rats received either closed head injury or sham injury using a weight‐drop. After recovery from closed head injury, rats then underwent extinction. Results showed no significant difference (p > 0.05) between closed head injury and sham‐injured groups, suggesting that concussive brain injury does not affect the ability to extinguish fear. We are currently examining changes in neuronal activity in brain regions relevant to fear, such as the amygdala and prefrontal cortex, using cFos immunohistochemistry.
Keywords: Concussion/mTBI
ATTENUATION OF INFLAMMATION WITH INTRAVENOUS IMMUNOGLOBULIN G (IVIG) IN DEGENERATIVE CERVICAL MYELOPATHY LEADS TO ENHANCEMENT OF NEUROLOGICAL RECOVERY FOLLOWING SURGICAL DECOMPRESSION
1University Health Network, North York, Canada, 2Universidad Católica de la Santísima Concepción, Concepción, Chile
Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord impairment worldwide.. Although DCM is currently treated with decompression (DEC), many patients are left with neurological deficits. Here, we postulated that intravenous administration of the FDA‐approved immunomodulatory drug IgG (IVIG) can effectively reduce vascular disruption and inflammation, as well as improve neurological outcome post‐DEC, resulting in improved behavioural recovery. We used a validated IVIG‐infusion protocol in a murine model of DCM. The murine model of DCM was associated with neuronal loss, inflammation, reduced spinal cord blood flow, and increased blood vessel density. We showed that these changes recapitulated human DCM using post‐mortem samples. In the DCM mice that underwent DEC, surgery significantly improved functional vascularity relative to DCM, however the inflammatory response remained pronounced due to ischemia reperfusion injury (IRI). IVIG‐infusion in both DCM and DEC animals significantly reduced inflammation and increased laminin expression in the basement membrane of blood vessels. This was accompanied by improved spinal cord blood flow and behavioural recovery, as evidenced by changes in forelimb swing speed, stride length and overall speed compared with saline controls. Taken together, our results provide evidence that IVIG may attenuate the systemic immune response in DCM and the localized immune response following surgical intervention by reducing IRI observed following DEC. As such, the use of IVIG represents a potential non‐surgical adjunctive treatment strategy for DCM in concert with DEC.
Keywords: Secondary Injury, Neurodegeneration, Blood Brain Barrier, Hypoxia/Ischemia, Vascular, Inflammation/Immune Function, Cervical
REMOTE ISCHEMIC PRECONDITIONING ATTENUATES ISCHEMIA REPERFUSION INJURY AND AIDS FUNCTIONAL RECOVERY FOLLOWING SURGICAL DECOMPRESSION OF DEGENERATIVE CERVICAL MYELOPATHY
1University Health Network, Toronto, Canada, 2Tokai University, Hiratsuka, Japan
Degenerative cervical myelopathy (DCM) is caused by progressive compression of the cervical spinal cord. Surgical decompression (DEC), while effective in most cases, results in ischemia reperfusion injury (IRI) and hinders a return to baseline function. Remote ischemic preconditioning (RIPC) is a non‐invasive intervention that uses transient ischemia distal to the site of injury to protect the host from ischemic insult. In this study, we posit that RIPC prior to DEC will enhance neurological recovery through the amelioration of DEC‐induced IRI. DCM was induced in mice and at 12‐weeks they either underwent: 1) RIPC prior to DEC; or 2) DEC alone (n = 50, respectively). Acute (24h post‐DEC) and chronic (5wk post‐DEC) cohorts were subjected to molecular and Catwalk gait analysis. Acutely, RIPC resulted in a significant decrease of nearly all proinflammatory markers relative to DEC alone (p < 0.05) and markedly reduced astrogliosis. Chronically, RIPC animals significantly outperformed both DEC and DCM groups in nearly all gait metrics and returned to pre‐DCM baselines (p < 0.05). RNA‐seq revealed that RIPC negated the change of thousands of DEC‐associated genes and combined with Western blotting we show that RIPC upregulates PPARγ, an inhibitor of STAT3, which is a critical activator of IRI‐mediated astrogliosis. In conclusion, RIPC when performed prior to DEC, reduces neuroinflammation and confers robust long‐term neurological recovery relative to DEC alone.
Keywords: Neuroprotection, Secondary Injury, Astrocyte, Neurodegeneration, Blood Brain Barrier, Gene Expression, Therapeutics/Drug Discovery, Vascular, Cervical, Informatics
INFLAMMATORY BIOMARKERS IN ELDERLY CHRONIC SUBDURAL HEMATOMA PATIENTS
1University of Pittsburgh, Pittsburgh PA, United States
Keywords: Biomarker, Aging, Inflammation/Immune Function, Neurocritical Care
AN EXPLORATORY STUDY ON FUNCTIONAL CONNECTIVITY AFTER MILD TRAUMATIC BRAIN INJURY; PRESERVED GLOBAL BUT ALTERED LOCAL ORGANIZATION
1Seoul National University Hospital, Seoul, Republic of Korea
Grant
NRF‐2018R1C1B6002554 and 2021R1A2B5B02087294
Keywords: Concussion/mTBI
APPLICATION OF UNSUPERVISED MACHINE LEARNING APPROACH TO CATEGORIZE PATIENTS WITH TRAUMATIC SPINAL CORD INJURY
1University Of Ottawa, Ottawa, Canada, 2Ottawa Hospital Research Institute, Ottawa, Canada
Keywords: Rehabilitation, Informatics
MYELOID DERIVED SUPPRESSOR CELLS IN TRAUMATIC BRAIN INJURY
1UTHealth, Houston TX, United States
Traumatic brain injury (TBI) affects 1.7 million people annually, and contributes to over 30% of injury‐related deaths in the United States with an estimated cost of over $76 billion. TBI patients suffer long‐lasting immune dysfunction that results in opportunistic infections. Studies in cancer and other chronic inflammatory diseases have found that a particular specialized immune cell type, called a Myeloid Derived Suppressor Cell (MDSC), is capable of paralyzing the immune system. This cell usually participates in an anti‐inflammatory response intended to help restore balance to the immune system once an injury or infection has been resolved. However, in the case of severe injury or disease, these cells may contribute to a broken feedback loop. Here, we present a flow cytometry‐based analysis of MDSC in the brain (contralateral and ipsilateral to TBI), spleen, and blood at 1, 3, 7, and 14 days after TBI using the controlled cortical impact model. We use CD11bc+ and His48+ to identify MDSC and evaluate their activation of additional markers RP‐1, RT1B, CD45, and CD172a. We also chose to apply the t‐distributed stochastic neighbor embedding (tSNE) algorithm which allows the compression of the fluorescent parameters into two‐dimension plots. The tSNE analysis showed increased expression in the spleen of CD11bc, His48, RT1B, CD172a, but an overall decreased expression of RP‐1 compared to brain samples at 7 days after TBI. The results from flow cytometry analysis demonstrated that systemic MDSC biomarkers can vary depending on the time following TBI.
Keywords: Pediatric
GLUTAMATE ACTIVATES A PROLIFERATIVE AND ASTROGLIOGENIC PROGRAM IN EPENDYMAL STEM CELLS: IMPLICATIONS FOR REGENERATIVE THERAPEUTIC TRANSLATION
1University Of Toronto, Toronto, Canada
The adult spinal cord contains a population of ependymal derived neural stem/progenitor cells (epNSPCs) that are normally quiescent, but are activated to proliferate, differentiate, and migrate after spinal cord injury (SCI). Once activated, epNSPCs serve as critical players in modulating the injury environment. However, epNSPC numbers remain insufficient for adequate regeneration in the subacute and chronic injury period. The factors that regulate epNSPC proliferation and differentiation in response to cellular stress and injury remain largely unknown. Elucidating these mechanisms is essential in regulating endogenous neural stem cells and further enhancing their regenerative potential. Glutamate excitotoxicity is a hallmark of SCI, and while toxic to neurons and glia, we recently discovered that excitotoxic levels of glutamate paradoxically lead to activation of epNSPCs. Herein, we demonstrate that glutamate leads to calcium influx in epNSPCs via AMPA receptors (AMPARs). Through a combination of RNAseq and protein analysis, we demonstrate that this change in calcium in concert with Notch signaling serve to increase the proliferation of epNSPCs via pCREB, and induce astrocytic cell fate specification through Hes1 upregulation. Using a clinically relevant in vivo model of SCI we demonstrate that positive allosteric modulation of AMPARs after injury enhances epNSPC proliferation, astrogliogenesis, neurotrophin production and promotes neuronal survival and early functional recovery. Our study uncovers an important mechanism by which glutamatergic signaling via AMPARs alters the proliferation and phenotype of epNSPCs. Pharmacological modulation of AMPAR signaling offers an important therapeutic strategy to regulate the fate of epNSPCs and better harness their regenerative potential after SCI.
Keywords: Excitotoxicity, Secondary Injury, Stem Cells, Regeneration & Plasticity
POST‐TRAUMATIC EPILEPSY: A RETROSPECTIVE STUDY FROM A TERTIARY TRAUMA CENTER IN MALAYSIA
1Neuropharmacology Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Subang Jaya, Malaysia, 2Neurology Unit, Department of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Malaysia, 3Neuropharmacology Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Subang Jaya, Malaysia, 4Global Public Health, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Subang Jaya, Malaysia, 5School of Pharmacy, Monash University Malaysia, , Bandar Sunway, Subang Jaya, Malaysia, 6Epilepsy Program, Neurology Department, Ruber Internacional Hospital, Spain
Keywords: Epilepsy/Seizure