Protective Mechanism of Berberine on Human Retinal Pigment Epithelial Cells against Apoptosis Induced by Hydrogen Peroxide via the Stimulation of Autophagy.

Shuai Li,Wenshu Zhou,Qin Li,Yizhou Jiang,Ruohong Lin,Wenhua Zheng,Xingan Xing,Wei Qiu,Ji Bihl

doi:10.1155/2021/7654143

Abstract

Age-related macular degeneration (AMD) is a major cause of severe and irreversible vision loss with limited effective therapies. Diminished autophagy and increased oxidative damage caused by ROS in the retinal pigment epithelium (RPE) have been implicated in the pathogenesis of AMD, and strategies aimed at enhancing autophagy are likely to protect these cells from oxidative damage. We have previously shown that berberine (BBR), an isoquinoline alkaloid isolated from Chinese herbs, was able to protect human RPE cells from H2O2-induced oxidative damage through AMPK activation. However, the precise mechanisms behind this protective effect remain unclear. Given the essential role of AMPK in autophagy activation, we postulated that BBR may confer protection against H2O2-induced oxidative damage by stimulating AMPK-dependent autophagy. Our results showed that BBR was able to induce autophagy in D407 cells, whereas autophagy inhibitor PIKIII or silencing of LC3B blocked the protective effect of BBR. Further analysis showed that BBR activated the AMPK/mTOR/ULK1 signaling pathways and that both pharmacological and genetic inhibitions of the AMPK pathway abolished the autophagy-stimulating effect of BBR. Similar results were obtained in primary cultured human RPE cells. Taken together, these results demonstrate that BBR is able to stimulate autophagy in D407 cells via the activation of AMPK pathway and that its protective effect against H2O2-induced oxidative damage relies on its autophagy-modulatory effect. Our findings also provide evidence to support the potential application of BBR in preventing and treating AMD.

Highlights

Age-related macular degeneration (AMD) is a leading cause of vision loss in aged people with a great impact in their quality of life
Primary cultured human retinal pigment epithelial cells were obtained from the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center with approval of the Ethics Committee of Zhongshan Ophthalmic Center (2018KYPJ082, 15 May, 2018). 3-(4,5Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), fetal bovine serum (FBS), bovine serum albumin (BSA), Dulbecco’s modified Eagle’s medium (DMEM), and 0.25% trypsin were obtained from GIBCOTM (Grand Island, NY, USA)
To evaluate the protective effect of BBR against H2O2-induced cell death, D407 cells were pretreated with different doses of BBR for 2 h before being exposed to 100 μM H2O2 for 24 h taking into consideration the doses used previously [19]

Summary

Introduction

Age-related macular degeneration (AMD) is a leading cause of vision loss in aged people with a great impact in their quality of life. Affecting the macula of the retina, it causes a chronic and progressive vision loss [1]. Late AMD can be divided into neovascular (wet) and nonneovascular (dry) forms [1]. In neovascular AMD, choroidal neovascularization causes fluid and blood leakage and leads to macula damage [2]. Nonneovascular AMD, called geographic atrophy, accounts for approximately 90% of AMD cases and is characterized by the progressive atrophy of retinal photoreceptors, choriocapillaris, and the retinal pigment epithelium (RPE) [3]. The use of anti-VEGF therapies, such as ranibizumab and bevacizumab, has been effective in the treatment of neovascular AMD [4]. There is no effective treatment for nonneovascular AMD

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