Arbutin inhibits inflammation and apoptosis by enhancing autophagy via SIRT1

Background: SIRT1 plays a protective role against diabetic retinopathy as it regulates inflammation, apoptosis and autophagy of cells.

Objectives: This study was designed to investigate the effects of arbutin and to identify a potential mechanism of action. Adult human retinal pigment epithelial (ARPE-19) cells were exposed to high glucose (HG) or treated with different concentrations of arbutin.

Material and methods: The protein levels of pro-inflammatory cytokines, like tumor necrosis factor-α (TNF-α), interleukin (IL)-1β), IL-6, and p65 were assessed using enzyme-linked immunosorbent assay (ELISA). The expression of NF-κB p65 and cyclooxygenase-2 (COX-2) was detected with western blot assay. Cell apoptosis was analyzed with TUNEL assay, and expression levels of Bcl2, BAX, cleaved caspase-3, cleaved PARP, LC3II, LC3I, and beclin1 were detected with western blot assay. Autophagy levels were detected using LC3II immunofluorescence staining.

Results: Arbutin treatment markedly enhanced viability and autophagy mediators, decreased pro-inflammatory proteins and reduced apoptosis in ARPE cells under HG exposure, while increasing SIRT1 protein level. This could be blocked by Sirtinol treatment. Additionally, 3MA treatment significantly reduced the efficacy of arbutin against inflammatory markers and apoptosis in ARPE cells exposed to HG.

Conclusions: Arbutin suppressed inflammation and apoptosis of ARPE cells induced by HG by promoting autophagy via SIRT1. A potential target, SIRT1, was identified for the treatment of DR, and new effects of and action mechanisms for arbutin were found and confirmed.