Rejuvenation Research

Findings on the association of both nicotinamide mononucleotide (NMN) and iron metabolism with antiaging or aging led us to speculate that some pharmacological functions of NMN may be achieved partially by affecting iron metabolism. Here, we investigated the effects of NMN on cell viability, iron contents, oxidative stress, and the expression of ferritins, transferrin receptor 1 (TfR1), ferroportin1 (Fpn1), hepcidin, interleukin 6 (IL-6), interleukin-1β (IL-1β), and signal transducer and activator of transcription 3 (STAT3) in BV2 microglia (BV-2) cells treated with 150 μM of ferric ammonium citrate. We found that NMN induced a significant reduction in iron concentration, ferritin expression, and reactive oxygen species level, and an increase in cell viability in iron-overloaded BV-2 cells. Also, NMN significantly up-regulated TfR1 and down-regulated Fpn1 and hepcidin expression as well as IL-6, IL-1β, and pSTAT3 contents in iron-overloaded BV-2 cells. We concluded that NMN is able to regulate the expression of iron transport proteins TfR1 and Fpn1, via IL6/STAT3/hepcidin and IL-1β/hepcidin pathways, and then down-regulate iron contents and the expression of ferritin and inhibit oxidative stress in iron-overloaded BV-2 microglia cells, supporting that some pharmacological functions of NMN may be partly associated with the effects of NMN on iron metabolism. Our results suggest that NMN may have beneficial therapeutic effects on iron-related diseases such as neurodegenerative diseases.

The aim of this study was to find potential drug targets of knee osteoarthritis (KOA) through druggable genome and Mendelian randomization (MR) analysis. Through integrating data from expression quantitative trait loci at different tissue and cellular levels, we identified potential therapeutic targets for KOA using drug target MR and single-cell MR analyses. Based on peripheral protein quantitative trait locus (pQTL) data, we validated the identified targets at the proteomic level using summary data-based MR and Heterogeneity in Dependent Instrument tests. Meanwhile, we used mediation MR analysis to explore possible mechanisms of action of the identified targets in KOA. To capture tissue specificity, we further applied the genetically informed spatial mapping (gsMap) framework, integrating KOA genome-wide association studies with spatial transcriptomics of E16.5 mouse embryonic tissues. We identified 12 and 5 potential therapeutic targets for KOA from peripheral and central tissues, respectively. Mitogen-activated protein kinase (MAPK3) and MARK3 were validated at the proteomic level, with MAPK3 showing a genetic association with reduced risk against KOA in both peripheral and central tissues. Single-cell MR analysis revealed that Lymphocyte antigen 6 D (LY6D) was associated with an increased risk of KOA in exogenous cells, MAPK3 showed a protective association in inhibitory neuron cells, and transforming growth factor alpha (TGFA) was associated with a reduced risk of KOA in oligodendrocyte precursor cells. Mediation MR analysis showed that body mass index (BMI) played a 16.6% mediating role in the causal association between MAPK3 and KOA. GsMap analysis revealed significant enrichment of KOA signals in cartilage primordium, cartilage, lung, and brain tissues. Finally, we proposed 16 potential therapeutic targets for KOA from both central and peripheral perspectives. Meanwhile, we found that BMI served as a mediator to mediate the causal effect between MAPK3 and KOA. Further experiments are needed in the future to verify the mechanism of action of the targets identified in this study in KOA.

Ischemic stroke (IS) is the worldwide leading cause of death and disability, so finding new approaches to prevent and treat IS has become urgent. Naomaili granules (NML), a proprietary Chinese medicine modified from Buyang Huanwu Decoction, has significant beneficial effects in treating IS. The present study demonstrated that NML significantly narrowed the volume of cerebral infarction in rats after middle cerebral artery occlusion (MCAO)/reperfusion (R), and in addition, improved their neurological function and reduced neuronal cell damage. Moreover, NML suppressed endoplasmic reticulum (ER) stress in MCAO/R rats and attenuated cellular pyroptosis by inhibiting the Ras Homolog Family Member A (RhoA)/pyrin pathway. In conclusion, the present study demonstrated that cerebral ischemia/reperfusion-induced ER stress in rat cortical neurons and may mediate pyroptosis of the cortical neurons through RhoA/pyrin. Meanwhile, NML reduced neuronal death and improved neurological function in rats by inhibiting ER stress and the RhoA/pyrin cellular pathway.

Agrin-mediated neuromuscular junction (NMJ) morphological alterations is one of the main pathogeneses of sarcopenia. The aim of this study was to observe the changes in serum agrin in patients with different degrees of sarcopenia and the alterations in Agrin receptors in human skeletal muscle with age. A total of 236 elderly subjects were enrolled and categorized into nonsarcopenia, possible sarcopenia, sarcopenia, and severe sarcopenia groups. Serum levels of the C-terminal Agrin fragment were quantified using an Enzyme-Linked Immunosorbent Assay (ELISA) kit. In addition, in a distinct and smaller exploratory subgroup (n = 12), quantitative real-time polymerase chain reaction and immunofluorescence staining were performed to investigate the expression of Agrin receptors, specifically low-density lipoprotein receptor-related protein 4 (Lrp4) and alpha-dystroglycan (α-DG), in human skeletal muscle samples. Compared with that in the nonsarcopenia group, the level of agrin in the other groups was significantly different. Partial correlation analysis and binary logistic regression analysis suggested that the level of Agrin was associated with handgrip strength. There was a significant increase in the serum level of agrin and a reduction in the mRNA expression of the agrin receptors Lrp4, α-DG, and RAPSN, while immunofluorescence analysis confirmed the expression patterns of the Lrp4 and α-DG receptors. In the elderly population, the level of agrin decreased in patients with sarcopenia, while the expression of its receptors also decreased. These factors result in NMJ morphological alterations, weakened muscle contraction, and increased risk of sarcopenia.

Taurine and tauroursodeoxycholic acid are used for treating cerebral ischemia. In this study, we used the combination of taurine and tauroursodeoxycholic acid to establish a model of ischemia-reperfusion injury and evaluate the effect and target of the drug combination using the neurovascular unit (NVU) model of hypoxia and reoxygenation in vitro. Results showed that the combined application of these two drugs improved the survival of neurons, astrocytes, and endothelial cells; reduced inflammatory damage, levels of tumor necrosis factor-alpha, interleukin (IL)-6, and IL-1β, oxidative stress response, and the release of malondialdehyde and nitric oxide; and enhanced the activity of superoxide dismutase. Simultaneously, they acted on the blood–brain barrier (BBB) and improved the transendothelial electrical resistance value, reduced lactate dehydrogenase levels, improved the activity of γ-glutamyl transferase, and protected the integrity of the BBB against damage caused by oxygen-glucose deprivation/reoxygenation. At the same time, they prevented neuronal apoptosis, reduced the expression of Bax and caspase-3, and increased the expression of Bcl-2. These two drugs regulated the expression of connexin 43 (CX43) and aquaporin 4 (AQP4) in astrocytes, reducing the level of AQP4, and improving the activity of CX43. In addition, the drug combination increased the expression of tight junction proteins in endothelial cells, such as zona occludens-1, occluding, and claudin-5, and decreased the expression of matrix metalloproteinase (MMP)2 and MMP9. Furthermore, they acted together on the p38 mitogen-activated protein kinase (MAPK) signaling pathway, and the addition of the p38 inhibitor SB203580 partially inhibited the expression of p38MAPK. Thus, the combined action of these drugs protected the NVU.