[Nitric oxide, biomarker of experimental autoimmune uveitis induced by S antigen].

INTRODUCTION

uveitis is an intraocular inflammation and one of the most severe and frequent manifestations of Behçet disease. S antigen (S Ag) is a highly conserved retinal protein implicated in the mechanism of the physiopathology in Behçet disease. This autoantigen is used in different animal models for experimental autoimmune uveitis (EAU) development, particularly in Behçet uveitis. Nitric oxide (NO) production has been reported in this disease by several groups and mainly by our team.

MATERIALS AND METHODS

in this study, we investigated the development of Behçet uveitis in an experimental model using the Wistar rat after treatment with S antigen. This antigen was isolated and purified from bovine retina by gel filtration chromatography using Sephadex G-200. The rats were immunized with 10μg of S Ag. We evaluated the changes in nitric oxide metabolite production in plasma using the Griess reaction, during the 7th, 14th, and 21st days post-immunization. Furthermore, deleterious effects by S antigen on retinal tissue were assessed in a histological study.

RESULTS

the results showed a significant increase in NO production in Wistar rats treated with S Ag in comparison with controls. We noted with interest that the clinical stages of EAU correlated with NO production. Furthermore, S Ag had several deleterious effects on Wistar rat retina.

CONCLUSION

this study indicated in vivo elevation of NO levels, which was observed before retinal tissue damage. Nitric oxide appears to be a good marker for a poor prognosis in this experimental model. Moreover, oxidative stress can be considered the primary step in pathogenesis inducing the destruction of retinal photoreceptors. Collectively, our data could be helpful in the development of strategies for diagnosing patients with Behçet uveitis.