Interleukin-17 induces angiogenesis in human choroidal endothelial cells in vitro.

PURPOSE The proinflammatory cytokine interleukin-17 (IL-17) has recently been shown to promote angiogenesis. In addition, a receptor for IL-17, IL-17 receptor C (IL-17RC), is enriched in patients with wet, age-related macular degeneration (AMD), a disease characterized by the formation of choroidal neovascularization. However, the role of IL-17 in choroidal endothelial cells (CECs) angiogenesis has not been defined. This study was conducted to determine the effect of IL-17 on proliferation, migration, and tube formation of human CECs. METHODS Expression patterns of IL-17 receptor A (IL-17RA) and IL-17RC on isolated human CECs were analyzed by flow cytometry and immunofluorescent staining. Proangiogenic effects of IL-17 on CECs was determined by proliferation assays with a water-soluble tetrazolium cell proliferation reagent kit, wound healing migration assays, and tube formation assays using basement membrane matrix. Cytoskeletal changes were observed by F-actin immunofluorescent staining. Activated Rac1 and RhoA levels were analyzed by pull-down assays. RESULTS Interleukin-17RA and IL-17RC were present on human CECs. Interleukin-17 enhanced migration and tube formation but did not affect proliferation. Moreover, IL-17 induced rearrangement of the actin cytoskeleton and upregulated activated Rac1 and RhoA in CECs. The PI3K inhibitor wortmannin suppressed CEC migration, cytoskeleton rearrangement, and upregulation of activated Rac1 and RhoA induced by IL-17. CONCLUSIONS Interleukin-17 elicits a proangiogenesis effect on human CECs in vitro by promoting migration and tube formation. The promoted migration effect was dependent on PI3K-Rac1 and RhoA-mediated actin cytoskeleton remodeling.