PEDF prevents reactive oxygen species generation and retinal endothelial cell damage at high glucose levels

Oxidative stress is associated with the development of retinopathy in diabetes; dietary supplementations of multi-antioxidants have no beneficial effects clinically. An antioxidant which could specifically target pathogenesis of diabetic retinopathy is the need of the hour. Pigment epithelium-derived factor is a potent, endogenously produced, multifunctional factor (neurotrophic, anti-angiogenic, anti-inflammatory etc.,) in the eye which recently was also shown to possess anti-oxidative action. However, its anti-oxidative effect against high glucose-induced oxidative stress in retinal endothelial cells has not been investigated. Here, we examined its anti-oxidative effect on cell morphology, survival, reactive oxygen species generation, lipid peroxidation, antioxidant status and caspase-3 activation under high glucose conditions in bovine retinal endothelial cells (BRECs). Cells grown at 33 mM glucose in the presence of PEDF at concentrations 10-50 nM did not exhibit shrinkage. Pigment epithelium-derived factor inhibited the high glucose-induced rise in reactive oxygen species generation and lipid peroxidation. In these cells, reduced glutathione levels and mitochondrial and superoxide dismutase activities increased markedly while reactive oxygen species generation decreased significantly in presence of PEDF as compared with cells grown in the absence of PEDF under high glucose conditions (10-20 nM, *p < 0.01&**p < 0.001; 30-50 nM, ***p < 0.0001). Our results suggest that pigment epithelium-derived factor has an anti-oxidant effect in bovine retinal endothelial cells at a high glucose level. The action of pigment epithelium-derived factor not only varies with the cell type but also depends on its concentration and environmental conditions. Therefore, further studies are required to determine if pigment epithelium-derived factor might constitute a preventive and/or a curative treatment for retinal neovascularization.