Abstract
Purpose: :
Vascular endothelial growth factors (VEGF) play a critical role in choroidal neovascularization (CNV) in age related macular degeneration (AMD). Retinal pigment epithelium (RPE) is a key tissue involved in AMD pathogenesis. Our previous studies have shown that inflammatory cytokine mix (ICM) and TGF-β induce VEGF expression by human RPE cells (HRPE). In this study, we evaluated the role of resveratrol (RSV) in regulating the expression of VEGF by HRPE.
Methods: :
Primary cultures of HRPE derived from adult donor eyes were used. Confluent cultures grown in 24 well plates were treated with ICM (IFN-γ, 20 u/ml+TNF-α, 2 ng/ml+IL-1β, 2 ng/ml), TGF-β1 (2 ng/ml) or cobalt chloride (Cocl2, hypoxia mimic) in the presence of RSV in serum free medium for 24 h. Levels of secreted VEGF-A, VEGF-C, other cytokines and chemokines were determined by ELISA. VEGF mRNA expression was evaluated by RT-PCR.
Results: :
VEGF-A secretion was significantly enhanced by HRPE cells by ICM, TGF-β1 and Cocl2. RSV at 10 - 50 uM concentration exhibited dose dependent inhibition of VEGF-A secretion upregulated by ICM, TGF-β and Cocl2. RSV at 50 uM slightly decreased constitutively secreted VEGF-A. VEGF-C secretion was significantly enhanced in HRPE cells by ICM but not by TGF-β and Cocl2. RSV at 10 - 50 uM suppressed VEGF-C secretion induced by ICM in HRPE cells by 40 to 80%. These data demonstrate that RSV is a potent suppresser of VEGF secretion elevated during hypoxic and inflammatory conditions.
Conclusions: :
RSV suppressed the HRPE secretion of VEGF-A and VEGF-C that was upregulated by ICM in HRPE. VEGF-A secretion enhanced by TGF-β and hypoxia was also suppressed by RSV. Our results suggest that RSV inhibits expression of VEGF by HRPE cells under a variety of conditions such as inflammation and hypoxia. The potential usefulness of RSV, present in grapes and other plant derived products, may be considered as a neutraceutical in AMD.
Keywords: retinal pigment epithelium • vascular endothelial growth factor • age-related macular degeneration