Overexpression of Fibulin-5 in Retinal Pigment Epithelial Cells Inhibits Cell Proliferation and Migration and Downregulates VEGF, CXCR4, and TGFB1 Expression in Cocultured Choroidal Endothelial Cells

Purpose of the study: Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss. Fibulin-5 (FBLN5) plays a pleiotropic role in the pathogenesis of AMD. We examined whether the in vitro overexpression of FBLN5 in retinal pigment epithelial (RPE) cells alters the proliferation and migration of cocultured choroidal endothelial cells (CECs) and explored the possible mechanisms involved. Materials and methods: A recombinant lentiviral vector carrying the Fbln5 gene was generated to transduce rat RPE cells. The expression of FBLN5 in transduced RPE cells was detected by quantitative real-time PCR and Western blot. The transduced RPE cells were then cocultured with rhesus macaque CECs in a Transwell coculture system. The impact of overexpression of FBLN5 in RPE cells on CEC proliferation and migration was assessed, as well as the impact on the mRNA expressions of vascular endothelial growth factor (VEGF), C-X-C chemokine receptor type 4 (CXCR4), and transforming growth factor beta 1 (TGFB1). Results: Our results showed that a recombinant lentivirus carrying the Fbln5 gene, which could induce overexpression of FBLN5 in RPE cells, was successfully generated. Overexpression of FBLN5 in RPE cells inhibited cell proliferation and migration and downregulated the mRNA expressions of VEGF, CXCR4, and TGFB1 in cocultured CECs. Conclusions: These findings suggest that FBLN5 may interfere with choroidal neovascularization by downregulating VEGF, CXCR4, and TGFB1 expression and inhibiting CEC proliferation and invasion, intensifying interest in FBLN5 as a target for therapeutic intervention in neovascular AMD.