Xie Weijie, Zhou Ping, Qu Muwen, Dai Ziru, Zhang Xuelian, Zhang Chenyang, Dong Xi, Sun Guibo, Sun Xiaobo
Institute of Medicinal Plant Development, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.
Guang'anmen Hospital, Chinese Academy of Chinese Medical Sciences, Beijing, China.
Front Pharmacol. 2020 May 21;11:695. doi: 10.3389/fphar.2020.00695. eCollection 2020.
Hyperglycaemia-induced retinal microvascular endothelial cell apoptosis is a critical and principle event in diabetic retinopathy (DR), which involves a series of complex processes such as mitochondrial dysfunction and oxidative stress. Ginsenoside Re (Re), a key ingredients of ginseng, is considered to have various pharmacologic functions, such as antioxidative, inhibition of inflammation and anti-apoptotic properties. However, the effects of Re in DR and the related mechanisms of endothelial cell injury induced by high glucose (HG) exposure remain unclear. The present study was designed to investigate and evaluate the ability of Re to ameliorate HG-induced retinal endothelial RF/6A cell injury and the potential mechanisms involved in the hypoxia-inducible factor-1-alpha (HIF-1α)/vascular endothelial growth factor (VEGF) signaling regulated by phosphoinositide 3-kinase (PI3K)/AKT pathway. Our results showed that preincubation with Re exerted cytoprotective effects by reversing the HG-induced decrease in RF/6A cell viability, downregulation of apoptosis rate and inhibition of oxidative-related enzymes, thereby reducing the excess intracellular reactive oxygen species (ROS) and HG-triggered RF/6A cell injury. In addition, Western blot analysis results showed ginsenoside Re significantly increased HIF-1α expression in the cytoplasm but decreased its expression in the nucleus, suggesting that it reduced the translocation of HIF-1α from the cytoplasm to the nucleus, and downregulated VEGF level. Moreover, this effect is involved in the activation of the PI3K/Akt pathway. LY294002, a PI3K inhibitor, was used to block the Akt pathway. Afterwards, the effects of Re on the regulation of apoptotic related proteins, VEGF and HIF-1α nuclear transcription was partially reversed. These findings suggested the exerting protective effects of ginsenoside Re were associated with regulating of PI3K/AKT and HIF-1α/VEGF signaling pathway, which indicates that ginsenoside Re may ameliorates HG-induced retinal angiogenesis and suggests the potential for the development of Re as a therapeutic for DR.
高血糖诱导的视网膜微血管内皮细胞凋亡是糖尿病视网膜病变（DR）中的关键和主要事件，其涉及一系列复杂过程，如线粒体功能障碍和氧化应激。人参皂苷Re（Re）是人参的关键成分之一，被认为具有多种药理功能，如抗氧化、抑制炎症和抗凋亡特性。然而，Re在DR中的作用以及高糖（HG）暴露诱导内皮细胞损伤的相关机制仍不清楚。本研究旨在探讨和评估Re改善HG诱导的视网膜内皮RF/6A细胞损伤的能力以及参与磷酸肌醇3激酶（PI3K）/蛋白激酶B（AKT）途径调节的缺氧诱导因子-1α（HIF-1α）/血管内皮生长因子（VEGF）信号传导的潜在机制。我们的结果表明，预先用Re孵育可通过逆转HG诱导的RF/6A细胞活力下降、下调凋亡率和抑制氧化相关酶来发挥细胞保护作用，从而减少细胞内过量的活性氧（ROS）和HG触发的RF/6A细胞损伤。此外，蛋白质印迹分析结果显示人参皂苷Re显著增加了细胞质中HIF-1α的表达，但降低了其在细胞核中的表达，表明它减少了HIF-1α从细胞质向细胞核的转位，并下调了VEGF水平。此外，这种作用涉及PI3K/Akt途径的激活。PI3K抑制剂LY294002用于阻断Akt途径。之后，Re对凋亡相关蛋白、VEGF和HIF-1α核转录调节的作用部分被逆转。这些发现表明人参皂苷Re的保护作用与PI3K/AKT和HIF-1α/VEGF信号通路的调节有关，这表明人参皂苷Re可能改善HG诱导的视网膜血管生成，并提示Re作为DR治疗药物开发的潜力。
