Role of Extracellular Vesicles in Human Uveitis

Abstract Non-infectious uveitis (NIU) is a significant cause of blindness. It is an immune mediated disease however the exact pathogenesis remains elusive. Considerable evidence exists on the immunomodulatory effects of Extracellular Vesicles (EVs) in various diseases; but little is known on the role of EVs in uveitis patients. We have previously shown that cytokine stimulated ARPE19 cells, release EVs; these EVs are capable of inhibiting T cell proliferation, inducing proinflammatory cytokine production from monocytes and monocyte cell death, in PBMCs from uveitis patients. The purpose of this study was to isolate EVs from uveitis patients and to determine their immune-modulatory potential in-vitro. EVs were isolated from the serum of NIU patients using Size Exclusion Chromatography (SEC) and set up in culture with PBMCs or ARPE19 cells; after stimulation cells were stained to determine activation and cytokine production. A higher number of EVs were isolated from patients, as compared to healthy controls; but EVs from both, were of the appropriate size, had a low protein content and were positive for the exosome associated markers CD9, CD63 and CD81. EVs from patients expressed increased levels of CD8, CD29, CD44, and HLA-DR/DP/DQ, indicating their potential to activate cells in-vivo as compared to controls. An upregulation of CD69 and CD25 on T cells and increased IFNg production was observed when the cells were cultured with EVs from patients. Incubating ARPE19 cells with the EVs from patients, increased the expression of MCP1 and IL8 in the cells. Preliminary data indicates that EVs isolated from uveitis patients can induce a robust activation of cells in-vitro. Current experiments are underway to further substantiate these results.