IL-17介导小胶质细胞M1极化在视网膜新生血管疾病中的作用及机制研究

Retinal neovascular diseases are the major causes leading to irreversible blindness in China. The important role of immune inflammation in various vascular diseases has been gradually recognized, but the effect of currently available anti-inflammatory therapy is limited. Recently, microglia have been regarded as the most important innate immune cells located in retina, while its characteristics and function remain unknown. Previously, we found that IL-17-mediated inflammation was involved in the onset and development of retinal vascular diseases, and microglia undergo specific polarization to M1 state in retinal neovascularization model. Based on these findings and previous reports, we propose a novel hypothesis: IL-17 induced the M1 polarization of retinal microglia through STAT3 pathway promoting the pathological angiogenesis in retinal neovascular diseases. This project aims to explore whether IL-17 can induce the activation and polarization of retinal microglia in vivo and in vitro by knock-out mice and single cell sequencing, and clarify the underlying mechanism; to find out whether the regulation by IL-17-STAT3-M1 microglia could provide new clues to find novel specific immune regulator, so as to provide a new strategy for preventing retinal pathological neovascularization. These results will expand our understanding of the immunologic effect in retinal neovascular diseases and provide experimental and theoretical basis for exploring new targets of anti-angiogenesis therapy in retina.

视网膜新生血管性疾病是我国重大的难治性致盲眼病。近年来，免疫炎症在新生血管病变中的重要作用备受关注。小胶质细胞被认为是视网膜关键的固有免疫细胞，但其功能特征及在疾病中的作用至今尚未阐明，是否能够通过靶向调控小胶质细胞功能，抑制视网膜新生血管形成，是本课题研究的关键科学问题。我们前期发现促炎因子IL-17参与视网膜新生血管形成，并在视网膜新生血管模型中发现小胶质细胞呈现独特的M1促炎极化表型。由此提出新假说：IL-17经STAT3通路诱导视网膜小胶质细胞发生M1极化，促进病理性新生血管形成。本课题拟利用基因敲除鼠、单细胞测序等技术探索IL-17诱导视网膜小胶质细胞活化、极化的分子机制；以IL-17-STAT3-M1小胶质细胞极化通路为靶点，探索新的特异性免疫调控剂靶向调控小胶质细胞极化状态，抑制视网膜新生血管的有效性和可能性。研究结果将为探寻新型抗新生血管治疗策略提供实验依据和理论基础。

视网膜变性疾病是一类严重危害人类视功能的难治性致盲眼病，包括新生血管性疾病如糖尿病视网膜病变、氧诱导视网膜变性、老年性黄斑变性等多种疾病，现有治疗效果不佳。免疫炎症被认为是导致多种视网膜变性疾病的核心机制，因此阐明神经免疫炎症对视网膜病变的作用机制是视网膜变性疾病综合治疗的关键环节。本项目以视网膜固有免疫细胞小胶质细胞的免疫调控机制为主要研究内容，阐明了不同视网膜变性疾病模型的免疫炎症机制，为免疫调控视网膜组织微环境奠定基础，并创新性提出应用细胞外囊泡发挥免疫调控功能，改善微环境，促进视网膜损伤修复策略。.本项目首先明确了IL-17诱导的iNOS+小胶质细胞激活介导视网膜血管变性的新机制，为以IL-17-STAT3-iNOS-IL-6为靶点调控小胶质细胞，应用于视网膜变性的治疗提供实验依据。进一步，本项目首次在AMD患者及视网膜变性小鼠中发现IL-4表达明显下降，且IL-4主要来源于小胶质细胞。应用IL-4行玻璃体腔注射，发现IL-4可诱导RPE细胞的修复表型，缓解视网膜变性。由此提出IL-4通过上调RPE细胞中IL-4Rα和激活Nrf2，利用抗氧化和抗炎特性发挥保护功能的新观点。靶向IL-4/IL-4Rα-Nrf2轴或成为神经退行性疾病的潜在新疗法。.此外，本项目还探索发现了多种免疫制剂调控小胶质细胞表型及功能，改善视网膜微环境，延缓视网膜变性疾病的效应及分子机制，阐明了细胞外囊泡调控树突状细胞介导免疫反应，改善缺血损伤的机制；证明局部应用MSC-exo，可有效调控局部固有免疫细胞的免疫表型，重塑微环境，从而促进组织再生及视网膜神经损伤后修复，为眼科临床应用MSC-exo免疫治疗奠定基础。这些研究成果揭示了免疫调控干预视网膜病变的机制及靶点，开拓了视网膜变性疾病治疗的新策略。