School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, China.
Guangdong Lewwin Pharmaceutical Research Institute Co., Ltd., Guangdong Provincial Key Laboratory of Drug Non-clinical Evaluation and Research, TCM Non-clinic Evaluation Branch of National Engineering Research Center for Modernization of Traditional Chinese Medicine, Guangdong Provincial Center for Ophthalmic Drug Creation and Evaluation Engineering Technology, Guangzhou, Guangdong 510990, China.
Oxid Med Cell Longev. 2021 Nov 17;2021:4053276. doi: 10.1155/2021/4053276. eCollection 2021.
Dry age-related macular degeneration (dAMD) is a chronic degenerative ophthalmopathy that leads to serious burden of visual impairment. Antioxidation in retinal pigment epithelium (RPE) cells is considered as a potential treatment for dAMD. Our previous studies have showed that naringenin (NAR) protects RPE cells from oxidative damage partly through SIRT1-mediated antioxidation. In this study, we tested the hypothesis that the Nrf2 signaling is another protective mechanism of NAR on dAMD. NaIO-induced mouse retinopathy and ARPE-19 cell injury models were established. Immunochemical staining, immunofluorescence, and western blotting were performed to detect the protein expressions of Nrf2 and HO-1. In addition, ML385 (activity inhibitor of Nrf2) and zinc protoporphyrin (ZnPP, activity inhibitor of HO-1) were applied to explore the effect of NaIO or NAR. The results showed that NAR increased the protein expressions of Nrf2 and HO-1 in the retinas in mice exposed to NaIO at the early stage. NAR treatment also resulted in a stronger activation of Nrf2 at the early stage in NaIO-treated ARPE-19 cells. Moreover, inhibition of HO-1 by ZnPP weakened the cytoprotective effect of NAR. The constitutive accumulation and activation of Nrf2 induced by NaIO led to the death of RPE cells. However, NAR decreased the protein expressions of Nrf2 and HO-1 towards normal level in the mouse retinas and ARPE-19 cells exposed to NaIO at the late stage. Our findings indicate that NAR protects RPE cells from oxidative damage via activating the Nrf2 signaling pathway.
干性年龄相关性黄斑变性（dAMD）是一种导致严重视力损害的慢性退行性眼病。视网膜色素上皮（RPE）细胞的抗氧化作用被认为是治疗 dAMD 的一种潜在方法。我们之前的研究表明，柚皮素（NAR）通过 SIRT1 介导的抗氧化作用部分保护 RPE 细胞免受氧化损伤。在这项研究中，我们检验了 NAR 通过 Nrf2 信号通路对 dAMD 起保护作用的假设。建立了 NaIO 诱导的小鼠视网膜病变和 ARPE-19 细胞损伤模型。通过免疫化学染色、免疫荧光和 Western blot 检测 Nrf2 和 HO-1 的蛋白表达。此外，还应用了 ML385（Nrf2 活性抑制剂）和锌原卟啉（HO-1 活性抑制剂）来探讨 NaIO 或 NAR 的作用。结果表明，NAR 增加了早期暴露于 NaIO 的小鼠视网膜中 Nrf2 和 HO-1 的蛋白表达。NAR 处理还导致早期 NaIO 处理的 ARPE-19 细胞中 Nrf2 的激活更强。此外，HO-1 的抑制物 ZnPP 减弱了 NAR 的细胞保护作用。NaIO 诱导的 Nrf2 的组成性积累和激活导致 RPE 细胞死亡。然而，NAR 使晚期暴露于 NaIO 的小鼠视网膜和 ARPE-19 细胞中 Nrf2 和 HO-1 的蛋白表达降低至正常水平。我们的研究结果表明，NAR 通过激活 Nrf2 信号通路来保护 RPE 细胞免受氧化损伤。
