The Role And Mechanisms Of The Immunoregulatory Function Of RPE Cells In T Cells In The Development Of AMD

Background and Purpose:Age-related macular degeneration(AMD)is the leading cause of blindness in older people.The dysfunction of RPE cells and loss of photoreceptors were consider to be essential in the pathological progression in AMD.Recent researches have indicated AMD as an inflammatory disease,in which both innate,such as T cells and adaptive immunity,such as macrophages were involved.However,how immunoregulatory function of RPE cells in T cell subsets differentiation and triggered inflammation in AMD development was not elucidated.So,this study used A2E as an AMD risk factor to investigate how oxidative stress impaired immunoregulatory function of RPE cells in T cells immunity in vitro,so as to investigate the role of T subsets immunity in the development of AMD.Methods:First,mouse RPE cells or human ARPE19 cells were cocultured with na?ve T cells under T subsets polarization conditions,and flow cytometer was used to analyze the phenotypes and function of induced T subsets.Second,RPE cells were stimulated with A2E,and co-cultured with na?ve T cells under Th1,Th2,Th17,and regulatory T cells(Tregs)polarization conditions.Flow cytometer and qRT-PCR were used to detect the intracellular cytokines or transcript factors of the induced T cells subsets.Finally,ROS levels of RPE cells after stimulation of A2E were detected,and the factors and possible pathways involved in the A2E-laden RPE cells were analyzed through neutralization of IL-1?and inhibitors of COX2-PGE2 pathways.Results:First,we found that RPE cells could induce na?ve T cells into a Foxp3~+regulatory subset,which had immunosuppressive function.RPE cells could also inhibit the differentiation of effective T subsets Th1,Th2,Th17 differentiation.These results indicated that normal RPE cells had immunoregulatory function through inducing regulatory T cells and inhibiting effective T cell subsets Th1,Th2,and Th17cellls.Secondly,we researched the role of AMD related oxidative stress in the immunoregulatory function of RPE cells.We co-cultured A2E-laden RPE(A2E-RPE)cells and na?ve T cells and found that A2E-RPE induced T cells expressed a lower level of Foxp3.A2E-laden RPE cells induced T cells showed lower suppressive function on the proliferation of responder cells.We found that A2E-laden RPE cells could not reduce Th1 cells differentiation.However,A2E-laden RPE cells exhibited suppressive effects on Th2 cells and Th17 cells.Finally,we found A2E induced RPE cells into inflammatory status,which expressed high level of inflammatory factors and ROS.Through neutralized IL-1?,we found that IL-1?mediated the effect of A2E on reducing regulatory function of RPE cells in Th1 differentiation.Through analysis of PGE2 and COX2 expression in RPE cells and blocking COX2-PGE2 pathways in RPE cells,We found that COX2-PGE2 pathways might mediate regulatory function of RPE cells in Th1 immunity,which could be inhibited by A2E.These resucts indicated that A2E inhibited PGE2-COX2 pathways and promoted IL-1?production to impaire regulatory function of RPE cells.Conclusions:Our study demonstrated that A2E induced RPE cells oxdative stress and inhibited regulatory function of RPE cells in Th1 immunity in vitro through production of IL-1?and inhibition of COX2-PGE2 pathways.Our data indicate that A2E could suppress immunoregulatory function of RPE cells and adaptive immunity might play a role in the immune pathogenesis of AMD,suggesting that targeting RPE immunoregulatory function may represent a novel strategy in AMD treatment.