Abstract
Purpose: :
Vascular Endothelial Growth Factors (VEGFs) play critical roles in choroidal neovascularization (CNV) in age-related macular degeneration (AMD). Retinal pigment epithelium (RPE) and choroid are the key tissues in the pathogenesis of AMD. We have recently reported that inflammatory cytokines (ICM) upregulate VEGFs expression by human RPE cells (HRPE). Resveratrol (RSV), a phytoalexin polyphenol found in grapes and several plant products, was shown to have beneficial effects against many age-related diseases,but its usefulness for AMD is not known. In this study, we investigated the possible actions of RSV in regulating the expression of VEGFs by HRPE.
Methods: :
Primary cultures of HRPE were prepared from eyes from aged donors obtained from Eye Banks. Confluent cultures grown in 24 well plates were treated with ICM (IFN-γ, 100 u /ml + TNF-α, 10 ng/ml + IL-1β, 10 ng/ml [10x conc.]) at different concentrations (0.2x, 1x, 5x and 10x) in the presence of RSV (0 - 50 uM) for 24 h. HRPE cell viability was assessed using CellTiter 96 AQuoeous One reagent. Levels of VEGF-A, VEGF-C, pigment epithelial derived factor (PEDF) and endostatin in the culture supernatants were determined by ELISA. VEGF mRNA expression was evaluated by RT-PCR. Effects of RSV on HRPE cell migration and proliferation were studied by in vitro wound closure assay.
Results: :
HRPE cell viability was not significantly affected by RSV and RSV+ICM treatment for 24 hr. VEGF-A and VEGF-C secretion were significantly enhanced in HRPE cells by ICM even at very low (1x and 0.2x) concentrations. VEGF-A and VEGF-C secretion that was enhanced by ICM at a wide range of concentrations (0.2x-10x) was inhibited significantly by RSV in a dose (10 -50 uM) dependent manner. There were no significant effects of ICM and /or RSV on the secretion of two anti-angiogenic molecules, PEDF and endostatin by HRPE cells. These data demonstrate that RSV is a potent suppressor of both VEGF-A and VEGF-C secretion elevated during inflammatory conditions. RSV exhibited dose (0-50 uM) dependent inhibition of wound closure in confluent HRPE cultures.
Conclusions: :
Our results suggest that RSV inhibits expression of VEGFs in HRPE cells during inflammatory conditions, which are known to be associated with CNV in AMD. RSV also inhibited HRPE cell migration and /or proliferation. Thus, RSV or its derivatives have great therapeutic potential as nutraceutical in controlling choroidal and /or retinal neovascularization in AMD.
Keywords: age-related macular degeneration • retinal pigment epithelium • vascular endothelial growth factor