Liraglutide Up-regulation Thioredoxin Attenuated Müller Cells Apoptosis in High Glucose by Regulating Oxidative Stress and Endoplasmic Reticulum Stress

<b>Purpose</b>: Diabetic retinopathy (DR) has become one of the most important complications of diabetes which is the leading cause of vision impairment and blindness all over the world. Increasing evidence shows that reactive gliosis are basic pathological features of early DR. The study was aimed to explore the protective effect and mechanism of Liraglutide (LIRA) which has similar properties to Glucagon-like peptide-1 (GLP-1) on Müller cell damage induced by diabetes. <b>Materials and methods</b>: <i>In vitro</i>, the Müller cell was cultured in high glucose (HG) to establish the model of diabetic retinopathy. The apoptosis was detected using flow cytometry. Western blot and immunofluorescence were used to detect the expression of related proteins. DCFH-DA probe was used to detect the ROS generation. <b>Results</b>: The data showed that the apoptosis and the expression of GFAP were increased significantly with HG treatment. However, the apoptosis percentage and the expression of GFAP were decreased after LIRA treatment. Moreover, the expression of p-Erk/Nrf2/Trx-signaling pathway proteins was also up-regulated and the generation of ROS was decreased after LIRA treatment which was inhibited after treatment with U0126 (Erk inhibitor). Besides, endoplasmic reticulum stress (ER stress) related proteins were up-regulated after Trx down-regulation by transfection with sh-RNA. <b>Conclusions</b>: LIRA could protect Müller cells from HG-induced damage via activating p-Erk pathway through increasing Trx expression which attenuated oxidative stress and ER stress. Trx could play a key role in the process.

<b>研究目的</b>：糖尿病视网膜病变（Diabetic retinopathy, DR）是糖尿病最主要的并发症之一，目前已成为全球范围内视力受损与失明的首要诱因。越来越多的研究证据表明，反应性胶质增生是早期糖尿病视网膜病变的核心病理特征。本研究旨在探讨与胰高血糖素样肽-1（Glucagon-like peptide-1, GLP-1）功能相似的利拉鲁肽（Liraglutide, LIRA）对糖尿病诱导的Müller细胞（Müller cell）损伤的保护作用及其潜在分子机制。
<b>材料与方法</b>：<i>体外</i>（in vitro）实验中，采用高糖（high glucose, HG）环境培养Müller细胞，构建糖尿病视网膜病变细胞模型。采用流式细胞术（flow cytometry）检测细胞凋亡情况；通过蛋白质印迹法（Western blot）与免疫荧光技术（immunofluorescence）检测相关蛋白的表达水平；使用DCFH-DA探针（DCFH-DA probe）检测活性氧（reactive oxygen species, ROS）的生成量。
<b>结果</b>：实验数据显示，高糖处理可显著升高Müller细胞的凋亡率与胶质纤维酸性蛋白（glial fibrillary acidic protein, GFAP）的表达水平。而经利拉鲁肽干预后，细胞凋亡率与GFAP的表达水平均显著降低。此外，利拉鲁肽干预可上调p-Erk/Nrf2/Trx信号通路相关蛋白的表达，并减少ROS生成；而U0126（Erk抑制剂）处理可阻断上述效应。同时，通过转染短发夹RNA（short hairpin RNA, shRNA）下调硫氧还蛋白（Thioredoxin, Trx）的表达后，内质网应激（endoplasmic reticulum stress, ER stress）相关蛋白的表达水平显著上调。
<b>结论</b>：利拉鲁肽可通过上调Trx的表达激活p-Erk信号通路，从而减轻氧化应激与内质网应激，最终保护Müller细胞免受高糖诱导的损伤。硫氧还蛋白在该保护过程中发挥关键调控作用。