4-1BB信号通路在矽肺炎症纤维化发展过程中的免疫调控机制

Silicosis is the most severe and harmful occupational disease, which composed 50 percent of the pneumoconiosis. The pathological change of the silicosis is lung inflammation and fibrosis. Our previous data showed that the level of receptor induced by lymphocyte activation 4-1BB in silicosis mice was significant higher than that in control mice. As the co-stimulation factor of T cell activation, 4-1BB takes part in the immune regulation of many diseases. However, the immunological mechanism during the pathology process of silicosis is not clearly demonstrated yet. What’s more, the regulatory mechanism of 4-1BB during the immune response in silicosis chronic inflammation and fibrosis is investigated rarely. Firstly, our study tries to analyze the molecular regulatory mechanism of 4-1BB signal pathway on silica induced lung inflammation and fibrosis in silicosis animal model by using gene knockout mice and agonistic antibody. Secondly, our study tries to research the molecular mechanism of 4-1BB signal pathway activation and the regulation of T cell’s differentiation by using the primary cells culture of 4-1BB knockout mice in vitro. Finally, our study try to investigated the regulatory role and molecular mechanism of 4-1BB on silicosis patients’ fibrosis by testing the activation of 4-1BB and its related signal pathways. The aim of our study is to illustrate molecular mechanism of the activation of 4-1BB signal pathways and the regulation of 4-1BB pathway on silicosis lung fibrosis. It is believed that if we demonstrated the mechanism of 4-1BB activation and/or the immune regulation of 4-1BB on silicosis development successfully, the potential molecular targets will be provided to help delaying the development of silicosis and curing the lung fibrosis.

矽肺患者约占我国尘肺总病例的50%，是尘肺中危害最严重的一种职业病。矽肺的病理过程主要表现为肺部炎症纤维化。前期研究发现矽肺小鼠淋巴细胞活化诱导受体4-1BB的水平显著高于对照组。4-1BB是T细胞活化共刺激分子，参与调控多种疾病。目前对矽肺免疫调控机制尚未十分清楚，特别是4-1BB调控矽肺炎症纤维化的研究尚未见报道。本研究拟通过基因敲除及激活抗体干预等方法，利用矽肺动物模型，研究4-1BB信号通路调控矽肺炎症纤维化的作用及分子机制；利用4-1BB基因敲除鼠原代细胞，研究SiO2激活4-1BB信号通路及对T细胞分化的调控机制；利用矽肺患者临床样本，研究4-1BB信号通路对矽肺患者纤维化的调控作用及其机制。以探明矽肺中4-1BB信号通路激活及其调控矽肺炎症纤维化的分子机制。本项目有望为延缓和阻抑矽肺炎症纤维化发生发展提供潜在的免疫分子靶标。

矽肺是由于生产过程中长期吸入大量结晶型二氧化硅所引起的，以肺部广泛结节性纤维化为主的职业性疾病。矽肺是危害接尘工人健康最严重的职业病。由于二氧化硅粉尘难以从肺部移除，即使工人离开接尘环境肺纤维化仍可继续发展。因此，探究矽肺纤维化的发病机制，寻找有效的治疗靶点和延缓矽尘所致肺组织纤维化进展的，对预防和控制矽肺病具有十分重要的意义。.本研究以实验性矽肺模型小鼠，小鼠肺泡巨噬细胞系MH-S以及矽肺患者血液样本为研究对象，通过体内体外和矽肺患者检测三方面，探讨4-1BB信号通路在矽肺发生发展中的作用机制。在此基础上，本课题引入薯蓣皂苷探究其对矽尘导致肺纤维化的作用及其免疫调控机制。结果表明，矽肺模型小鼠肺组织4-1BB蛋白表达增高；阻断4-1BB信号通路可以减轻矽尘导致的肺部炎症和纤维化；阻断4-1BB信号通路可以减轻肺部Th免疫应答和循环纤维细胞向肺部聚集进而减轻肺纤维化；4-1BB信号通路可调控巨噬细胞分泌促炎及促纤维化细胞因子；矽肺患者外周血中Vδ2+γδT细胞、CD4+T和CD8+T细胞以及Tc1细胞表达4-1BB的比例显著降低。薯蓣皂苷可通过调控4-1BB蛋白下游信号通路减少巨噬细胞、T淋巴细胞、B淋巴细胞向肺部的聚集，进而减轻肺部炎症；薯蓣皂苷亦通过调节肺部Th免疫应答、减少循环纤维细胞向肺部的聚集以及减轻矽尘颗粒对肺泡上皮的损伤，减轻肺组织纤维化。.综合动物、细胞及矽肺患者研究结果，本研究证实4-1BB信号通路是延缓矽尘所致肺组织纤维化的潜在分子靶点。薯蓣皂苷对于先天、适应性免疫应答及循环纤维细胞的调节作用可为其应用提供可靠的理论和实验依据。