Trakkides, Timon-OrestTimon-OrestTrakkidesSchäfer, NicoleNicoleSchäferReichenthaler, MariaMariaReichenthalerKühn, KonstanzeKonstanzeKühnBrandwijk, Ricardo J M G ERicardo J M G EBrandwijkToonen, Erik J MErik J MToonenUrban, FlorianFlorianUrbanWegener, JoachimJoachimWegenerEnzmann, VolkerVolkerEnzmann0000-0003-4384-4855Pauly, DianaDianaPauly2024-10-282024-10-282019-11-13https://boris-portal.unibe.ch/handle/20.500.12422/184611Oxidative stress-induced damage of the retinal pigment epithelium (RPE) and chronic inflammation have been suggested as major contributors to a range of retinal diseases. Here, we examined the effects of oxidative stress on endogenous complement components and proinflammatory and angiogenic responses in RPE cells. ARPE-19 cells exposed for 1-48 h to H2O2 had reduced cell-cell contact and increased markers for epithelial-mesenchymal transition but showed insignificant cell death. Stressed ARPE-19 cells increased the expression of complement receptors CR3 (subunit CD11b) and C5aR1. CD11b was colocalized with cell-derived complement protein C3, which was present in its activated form in ARPE-19 cells. C3, as well as its regulators complement factor H (CFH) and properdin, accumulated in the ARPE-19 cells after oxidative stress independently of external complement sources. This cell-associated complement accumulation was accompanied by increased nlrp3 and foxp3 expression and the subsequently enhanced secretion of proinflammatory and proangiogenic factors. The complement-associated ARPE-19 reaction to oxidative stress, which was independent of exogenous complement sources, was further augmented by the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib. Our results indicate that ARPE-19 cell-derived complement proteins and receptors are involved in ARPE-19 cell homeostasis following oxidative stress and should be considered as targets for treatment development for retinal degeneration.encomplement system foxp3 inflammasome olaparib oxidative stress retinal pigment epithelial cells600 - Technology::610 - Medicine & healtharticle10.7892/boris.1370223176629510.3390/antiox8110548