Aflibercept, bevacizumab and ranibizumab prevent glucose-induced damage in human retinal pericytes in vitro, through a PLA2/COX-2/VEGF-A pathway

Diabetic retinopathy, a major cause of vision loss, is currently treated with anti-VEGF agents. Here we tested two hypotheses: (i) high glucose damages retinal pericytes, the cell layer surrounding endothelial cells, via VEGF induction, which may be counteracted by anti-VEGFs and (ii) activation of PLA(2)/COX-2 pathway by high glucose might be upstream and/or downstream of VEGF in perycites, as previously observed in endothelial cells. Human retinal pericytes were treated with high glucose (25 mM) for 48 h and/or anti-VEGFs (40 mu g/ml aflibercept, 25 mu g/ml bevacizumab, 10 mu g/ml ranibizumab). All anti-VEGFs significantly prevented high glucose-induced cell damage (assessed by LDH release) and improved cell viability (assessed by MTT and Evans blue). High glucose-induced VEGF-A expression, as detected both at mRNA (qPCR) and protein (ELISA) level, while receptor (VEGFR(1) and VEGFR(2)) expression, detected in control condition, was unaffected by treatments. High glucose induced also activation of PLA(2)/COX-2 pathway, as revealed by increased phosphoxylation of cPLA(2). COX-2 expression and PGE(2) release. Treatment with cPLA(2) (50 mu M AACOCF3) and COX-2 (5 mu M NS-392) inhibitors prevented both cell damage and VEGF-A induced by high glucose. Finally, challenge with exogenous VEGF-A (10 ng/ml) induced VEGF-A expression, while anti-VEGFs reduced VEGF-A expression induced by either high glucose or exogenous VEGF-A. These data indicate that high glucose directly damages pericytes through activation of PLA(2)/COX-2/VEGF-A pathway. Furthermore, a kind of feed-forward loop between cPLA(2)/COX-2/PG axis and VEGF appears to operate in this system. Thus, anti-VEGFs afford protection of pericytes from high glucose by inhibiting this loop. (C) 2015 Elsevier Inc. All rights reserved.