Abstract
Problem: Annexin A1 has been implicated in various cellular processes such as intracellular signal transduction, membrane skeletal linkage, proliferation, and differentiation. Additional functions have been postulated for this protein, in particular an inhibitory function of inflammatory processes. However, the studies of the expression of annexin A1 in normal respiratory mucosa are scarce, and none has been performed in inflamed nasal mucosa. The objective of this work is to determine the expression pattern of annexin A1 in normal nasal mucosa, nasal mucosa of patients with perennial rhinitis, and nasal polyps.
Methods: Annexin A1 expression was examined with a standard immunohistochemical protocol on paraffin sections of normal middle turbinates (n = 5), middle turbinates of patients with perennial rhinitis (n = 5), and nasal polyps (n = 7).
Results: Annexin A1 was highly expressed by ciliated cells, where it was concentrated on the apical surface and within the cilia. Goblet cells and nondifferentiated basal epithelial cells did not stain. In the glands of the lamina propria, intense staining was found in the cytoplasm and in the nucleus of the cells in the duct epithelium, whereas acinar cells did not stain. Intense cytoplasmic staining was observed in infiltrating polymorphonuclear cells and macrophages. No differences in the pattern or the level of expression of annexin A1 were found in the epithelial cells and glands between normal and chronically inflamed (perenial rhinitis or polyps) nasal mucosa.
Conclusion: These results suggest that the expression of annexin A1 in respiratory epithelium of nasal mucosa is related to the differentiation status of the cells and is not influenced by inflammatory diseases.
Significance: Intracellular annexin A1 does not appear to be implicated in chronic nasal inflammation.
Support: Supported by grant from Fondo de Investigaciones Sanitarias, Madrid, Spain (No. 00/0171).