Epigallocatechin-3-gallate stimulates autophagy and reduces apoptosis levels in retinal Müller cells under high-glucose conditions

Abstract

Retinal neurodegeneration is an early feature in the pathogenesis of diabetic retinopathy (DR). Autophagy is an intracellular catabolic process involved in protein and organelle degradation that has been linked in DR. Epigallocatechin gallate (EGCG) is a major polyphenol in green tea that has beneficial effects in diabetic. however, it is not currently known whether EGCG can regulate Müller cell autophagy. Here, we showed that EGCG increased autophagy by promoting the formation of autophagosomes, increasing lysosomal acidification, and stimulating autophagic flux in Müller cells, while high glucose (HG) induced a decrease in autophagy and an increase in apoptosis. However, retinal Müller cells in HG treated with EGCG showed autophagy machinery activation and reestablishment of cargo degradation, protecting the cells from apoptosis. EGCG could increase the ability of cells to proliferate by increasing autophagy. In an experimental model of diabetic retinopathy, EGCG reduced the reactive gliosis of Müller cells and decreased retinal damage. These results highlight that HG downregulates autophagy and accumulates P62 cargo due to lysosomal dysfunction and then increases apoptosis, which was reversed by treatment with EGCG. This finding might be valuable for developing a novel therapeutic strategy to treat DR.

Keywords: Apoptosis; Autophagy; Diabetes retinopathy; EGCG; Müller cells.