High IFN－α expression is associated with the induction of experimental autoimmune uveitis （EAU） in Fischer 344 rat

INTRODUCTIONThe CD4 T cells can be subdivided intoTh1 and Th2 subsets based on their secreted cy-tokine profile. Th1 cells characteristical1y secreteInterferonry (IFN--ry), whereas Th2 cells maiuly pro--duce IL--41]. IL-12 po1arizes the differentiation ofnaitre, CD4 T cells towards Th1 pathWay, in con-trast IL--4 directs T cell differentiation towards Th2pathWay The broken balance between Th1 and Th2immune responses and predominant Th1 responseare crucial factors in initiation…

High IFN-alpha expression is associated with the induction of experimental autoimmune uveitis (EAU) in Fischer 344 rat.

Th1-response plays a crucial role in determining pathogenesis of organ-specific autoimmune diseases. It is believed that both IL-12 and INF-a are initiators to regulate Th1-response. In our experimental autoimmune uveitis (EAU) model, both Lewis and Fischer 344 rats share the same MHC class II molecules, while Lewis rat is EAU susceptible and Fischer 344 rat is EAU resistant. However, under the same condition of immunization, if pertussis toxin (PTX) was injected intraperitoneally as an additional adjuvant, Fischer 344 rat can develop EAU. In this study we investigate which mechanisms are involved in the induction of EAU in CFA R16 PTX treated (CRP- treated) Fischer 344 rats. In vivo and in vitro data demonstrated that Th1-cytokine, IFN- mRNA expression was significantly increased in disease target tissue-eyes and in draining lymph node cells of CRP-treated Fischer 344 rat. When IL-12 and IFN-a mRNA expression were compared in the experimental groups, only IFN-a mRNA expression was associated with EAU development. To distinguish the sources of IFN-a producing cells, it was observed that IFN-a expression was mainly produced by macrophages. It was further confirmed that normal macrophage from Fischer 344 rat was able to produce significant IFN-a in the presence of PTX. The data strongly suggested that IFN-a might be involved in initiating Th1-cell differentiation and in turn contribute to the induction of EAU. High IFN-a expression induced by PTX may represent a novel pathway to initiate Th1 response in Fischer 344 rat.