Chlorogenic acid attenuates diabetic retinopathy by reducing VEGF expression and inhibiting VEGF-mediated retinal neoangiogenesis.

Diabetic retinopathy (DR) is one of the most common and serious complications of diabetes mellitus (DM). This study aims to investigate the amelioration of chlorogenic acid (CGA) on proliferative DR (PDR) via focusing on inhibiting retinal neoangiogenesis. CGA reduced the increased cell proliferation, migration and tube formation induced by vascular endothelial growth factor (VEGF) in human retinal endothelial cells (HREC) and choroid-retinal endothelial RF/6A cells. CGA abrogated VEGF-induced the phosphorylation of VEGFR2 and its downstream mitogen-activated extracellular regulated kinase (MEK1/2), extracellular regulated protein kinase (ERK1/2) and p38 kinase. CGA reduced high glucose (HG)-induced the activation of microglia BV-2 cells. CGA also reduced HG-induced the increased VEGF expression and hypoxia-inducible factor 1-alpha (HIF-1α) translocation into nucleus in BV2 cells. Retinal immunofluorescence staining with cluster of differentiation 31 (CD31) and retinal histopathological observation both demonstrated that CGA (1, 10mg/kg) decreased the increased retinal vessels in streptozotocin (STZ)-induced hyperglycemic mice. CGA reduced the elevated serum VEGF level and microglia activation in STZ-induced hyperglycemic mice. In conclusion, CGA inhibits retinal neoangiogenesis during the process of DR by abrogating HG-induced HIF-1α-mediated paracrine VEGF expression in microglia cells and inhibiting VEGF-induced angiogenesis in retinal endothelial cells.