树突状细胞在葡萄膜炎中调节CD4+T细胞活化的作用及分子机制

Uveitis is a CD4+ T-cell-mediated autoimmune disease, and it damages visual function seriously. However the treatment of disease is not efficient and pathogenesis of it is not completely clear. It is of great importance to further study the pathogenesis of uveitis for seeking an efficient method to treat this disease. Dendritic cell (DC) is considered to have a core role in the regulation of autoimmune disease. The mature state of it is associated with the activation of T cell. CD83 is a mature marker of DC, and plays an important role in regulating T-cell activation. High expression of CD83 in DC is found at the onset of uveitis. Therefore, we hypothesize that DC may affect the activation of CD4+ T cell by adjusting the expression of CD83 in the development of uveitis. In our previous experiment, we constructed living cell model of DC-CD4+ T cell interaction. On the basis of this, with flow cytometry and confocal microscopy, we will study the mature state of DC in the development of uveitis, and how DC regulates the migration, immunological synapse formation, activation of CD4+ T cell in the development process of experimental autoimmune uveitis. Furthermore, mCD83/sCD83 is studied to prove whether it involves in uveitis disease process, and whether it regulates F-actin arrangement to affect the cellular localization of ICAM-1 in DC, which further regulates the activation of CD4+ T cell. This study will elucidate the function and molecule mechanisms of DC in pathogenesis of uveitis, and seek a new target for treatment of uveitis.

葡萄膜炎是CD4+T细胞介导的、严重损害视功能的自身免疫性疾病。该病防治困难，发病机制尚不完全清楚，深入研究其发病机制对临床防治具有重要意义。树突状细胞（DC）在调节自身免疫性疾病中起核心作用，其成熟状态与T细胞活化密切相关。CD83是DC的成熟标志，在调节T细胞激活中起重要作用。葡萄膜炎发病期CD83在DC上高表达，因此我们推测DC可能通过CD83调节CD4+T细胞的活化，影响葡萄膜炎的发展进程。基于前期构建的DC-CD4+T细胞相互作用模型，本课题拟以实验性葡萄膜炎小鼠为研究对象，采用流式细胞术和激光共聚焦技术研究葡萄膜炎病程中DC的成熟状态及其调控CD4+T细胞活化的机制，探讨mCD83/sCD83通过调节F-actin调控ICAM-1在DC上的定位，进而调节CD4+T细胞活化的机制。本研究旨在阐明DC在葡萄膜炎发病过程中的作用及机制，为治疗葡萄膜炎提供的新靶点和思路。

树突状细胞（dendritic cells, DCs）是体内功能最强、唯一能激活静息T细胞的专职抗原提呈细胞，是启动、调控和维持免疫应答的中心环节。DCs广泛分布于肝脏、脾脏、肺脏等组织器官，在调节自身免疫性疾病中起核心作用。但目前关于眼中DCs的表型特征和功能及其调节机制尚不完全清楚。CD83是DCs的成熟标志，经水解后产生可溶性成分sCD83。sCD83在器官移植、多种自身免疫性疾病中起免疫调节作用，但sCD83对葡萄膜炎的调节作用以及对眼中DCs的功能及其调节尚不明确。本课题以实验性葡萄膜炎小鼠（EAU）为模型， 运用流式、激光共聚焦、Western-blot等技术，通过体内外实验研究发现：（1）正常小鼠眼内的存在一群CD11bhighCD11clowI-alow调节性DCs，疾病康复期这群细胞增加，参与实验性葡萄膜炎小鼠模型（EAU）眼内浸润的淋巴细胞数量和活性的调节，促进葡萄膜炎症状的缓解；眼内微环境促进了调节性DCs的形成；（2）炎症期成熟性DCs增加，通过细胞间相互作用促进炎性的T细胞增加；（3）葡萄膜炎的炎症期眼内sCD83浓度增高，sCD83作为一种抑制性小分子通过下调DCs细胞中骨架蛋白F-actin依赖的钙活化，进而下调T细胞活化，从而缓解EAU小鼠炎症症状、降低眼内淋巴细胞的浸润；（4）sCD83可通过下调活化的NK细胞亚群比例，促进EAU炎症的缓解。通过本项研究，阐明了葡萄膜炎发病的新机制，揭示了sCD83作为免疫抑制分子抑制葡萄膜炎发病的新机制，sCD83具有调节免疫作用对于治疗葡萄膜炎具有潜在的应用前景。