Hu Chengyu, Cui Tao, Xu Zihang, Yang Kun, Wu Yan, Cai Wenting, Yu Jing, Qiu Yaoyan
Department of Ophthalmology, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200072 China.
Tianjin Medical Device Evaluation and Inspection Center, Tianjin, China.
Int Immunopharmacol. 2025 Mar 6;149:114192. doi: 10.1016/j.intimp.2025.114192. Epub 2025 Feb 3.
Retinitis pigmentosa (RP) is an inherited retinal neurodegenerative disease which is a significant contributor to blindness. Microglia-mediated inflammation plays a crucial role in retinitis pigmentosa. However, the activation mechanisms of microglia and the role of polarized microglia in RP remain unclear. High-mobility group box 1 (HMGB1) is a key contributor to aseptic inflammation, and glycyrrhizin exerts anti-inflammatory effects by targeting HMGB1. This study aimed to investigate the role of HMGB1 and microglia in RP and explore the protective effects of glycyrrhizin on photoreceptors.
Male C57BL/6 mice and age-matched rd1 mice were used for in vivo models, while zaprinast-treated 661w cells and HMGB1-treated BV-2 cells were used for in vitro models. In this study, the expression of HMGB1 was analyzed using QPCR and western blot (WB). Immunofluorescence staining and ELISA were performed to assess HMGB1 translocation and secretion. Glycyrrhizin was used to inhibit HMGB1, while FPS-ZM1 served as an inhibitor of the receptor for advanced glycation end products (AGER). Microglial polarization was evaluated by QPCR, and the HMGB1/ AGER/ NF-κB signaling pathway was analyzed through WB. Photoreceptor degeneration and visual function were assessed through H&E staining, electroretinography, and TUNEL staining.
We observed elevated levels of HMGB1 in the retina of rd1 mice and demonstrated in vitro that photoreceptors may serve as a significant source of HMGB1 in the retina. Additionally, HMGB1 was observed to cause microglial polarization via the HMGB1/AGER/ NF-κB pathway and the polarized microglia secrete inflammatory factors including TNF-α and IL-1β which accelerates the degeneration of photoreceptors. Glycyrrhizin reversed the degeneration of photoreceptors and loss of visual function in rd1 mice through the HMGB1/AGER/ NF-κB pathway.
Our findings showed that HMGB1 secreted by photoreceptors activated the microglia through the HMGB1/AGER/NF-κB pathway and the polarized microglia accelerates the degeneration of photoreceptors. Glycyrrhizin reversed the polarization caused by HMGB1 in vitro and delayed the progression of RP in vivo, presenting a potential novel approach for treating retinitis pigmentosa.
视网膜色素变性（RP）是一种遗传性视网膜神经退行性疾病，是导致失明的重要原因。小胶质细胞介导的炎症在视网膜色素变性中起关键作用。然而，小胶质细胞的激活机制以及极化小胶质细胞在RP中的作用仍不清楚。高迁移率族蛋白B1（HMGB1）是无菌性炎症的关键促成因素，甘草酸通过靶向HMGB1发挥抗炎作用。本研究旨在探讨HMGB1和小胶质细胞在RP中的作用，并探索甘草酸对光感受器的保护作用。
雄性C57BL/6小鼠和年龄匹配的rd1小鼠用于体内模型，而用扎普司特处理的661w细胞和用HMGB1处理的BV-2细胞用于体外模型。在本研究中，使用实时定量聚合酶链反应（QPCR）和蛋白质免疫印迹法（WB）分析HMGB1的表达。进行免疫荧光染色和酶联免疫吸附测定（ELISA）以评估HMGB1的转位和分泌。使用甘草酸抑制HMGB1，而FPS-ZM1用作晚期糖基化终末产物受体（AGER）的抑制剂。通过QPCR评估小胶质细胞极化，并通过WB分析HMGB1/AGER/核因子κB（NF-κB）信号通路。通过苏木精-伊红（H&E）染色、视网膜电图和末端脱氧核苷酸转移酶介导的缺口末端标记（TUNEL）染色评估光感受器变性和视觉功能。
我们观察到rd1小鼠视网膜中HMGB1水平升高，并在体外证明光感受器可能是视网膜中HMGB1的重要来源。此外，观察到HMGB1通过HMGB1/AGER/NF-κB途径引起小胶质细胞极化，并且极化的小胶质细胞分泌包括肿瘤坏死因子-α（TNF-α）和白细胞介素-1β（IL-1β）在内的炎症因子，加速光感受器的变性。甘草酸通过HMGB1/AGER/NF-κB途径逆转rd1小鼠光感受器的变性和视觉功能丧失。
我们的研究结果表明，光感受器分泌的HMGB1通过HMGB1/AGER/NF-κB途径激活小胶质细胞，并且极化的小胶质细胞加速光感受器的变性。甘草酸在体外逆转了HMGB1引起的极化，并在体内延缓了RP的进展，为治疗视网膜色素变性提供了一种潜在的新方法。
