CD44-RhoA-YAP信号通路调控纤维母细胞活化及其在实验性矽肺中的作用机制研究

Silicosis accounts for about 50% of the total pneumoconiosis cases in China. It is the most serious kind of pneumoconiosis. The pathological process of silicosis is mainly characterized as progressive pulmonary fibrosis. In recent years, researchers have proposed a new concept for the pathogenesis of fibrosis: the synthesis of extracellular matrix plays a positive role in promoting the fibrosis mediated by fibroblast proliferation and activation. However, the exact molecular mechanism is not clear. Our previous study found that extracellular matrix could induce CD44 expression on fibroblast surface and lead to YAP protein higher expression in the nucleus; blocking CD44 can lead to a reduced nucleus expression of YAP; Besides, we found increased expression of nucleus YAP in lung sections of mice with experimental silicosis; The aim of this project is to explore the role of CD44-RhoA-YAP signaling in the activation of fibroblasts induced by extracellular matrix proteins. We expect to explore its role in the progression of experimental silicosis. This study intends to investigate the molecular mechanism of YAP expression in the nucleus induced by increased extracellular matrix proteins, and explore the effect of the signaling pathway on the activation of fibroblasts by upstream and downstream blockade. The role of CD44-RhoA-YAP signaling pathway in the progression of pulmonary fibrosis in mice could be elucidated by the animal models of experimental silicosis. This project can provide a new basis and potential molecular targets for delaying the progression of silicosis.

矽肺约占我国尘肺总病例的50%，是尘肺病中危害最严重的一种。矽肺的病理改变主要表现为肺组织纤维化。近年来，研究人员对纤维化的发病机理提出新的理念：细胞外基质的合成与纤维母细胞增殖活化所介导的纤维化之间存在正向促进作用。但其确切分子机制尚不明确。本课题组前期研究发现细胞外基质硬度增加可引起纤维母细胞CD44表达增高和YAP蛋白入核；实验性矽肺小鼠肺组织中YAP核内表达明显升高；体外阻断CD44可以使纤维母细胞YAP入核表达降低。本项目以细胞外基质导致纤维母细胞活化为切入点，拟通过体外实验证明细胞外基质蛋白可通过CD44-RhoA-YAP信号使纤维母细胞活化，并从上下游阻断该通路探究其对纤维母细胞功能的影响；进一步利用实验性矽肺动物模型，阐明该信号通路对矽肺纤维化进展的调控作用。本项目可为延缓矽肺纤维化的进展提供新的理论依据和潜在分子靶点。

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，以肺部纤维化为主的职业性肺疾病。矽肺约占我国尘肺总病例的50%，是尘肺病中危害最严重的一种。由于矽尘难以从肺部移除，即使工人离开接尘环境肺纤维化仍可进展。因此，探究矽肺纤维化的发病机制，寻找有效的治疗靶点延缓矽尘所致肺纤维化进展，对预防和控制矽肺病具有十分重要的意义。.近年来，研究人员对纤维化的发病机理提出新的理念:细胞外基质的合成与纤维母细胞增殖活化所介导的纤维化之间存在正向促进作用。但其确切分子机制尚不明确。本项目以细胞外基质诱导纤维母细胞活化为切入点，以小鼠胚胎纤维母细胞系NIH-3T3及实验性矽肺模型小鼠为研究对象，明确CD44-RhoA-YAP信号通路在机械力诱导纤维母细胞活化及矽肺纤维化进展中的作用。以NIH-3T3为研究对象，通过逐一沉默和逆转实验，构建CD44-RhoA-YAP信号通路，并证明细胞外机械应力可通过该信号活化纤维母细胞。CD44中和抗体，维替泊芬和二氢丹参酮均可阻断该信号通路影响纤维母细胞功能。以矽尘暴露模型小鼠为研究对象开展体内实验，通过CD44中和抗体，维替泊芬和二氢丹参酮处理分别从上下游阻断CD44-RhoA-YAP信号通路,明确阻断该通路可抑制小鼠肺纤维母细胞活化，延缓矽肺纤维化进程并明显改善矽肺小鼠肺功能。除此之外，本项目证明天然提取物二氢丹参酮I，可通过减少淋巴细胞在矽尘暴露小鼠肺组织浸润，抑制Th免疫反应，调节矽尘所致的适应性免疫应答，从而减轻矽尘所致肺部炎症反应。.本项目研究成果揭示了肺纤维化进展的一种新的分子机制，并为延缓矽肺纤维化进展提供了新的分子靶点和治疗策略，对其他类型的纤维化疾病的基础研究同样具有重要的借鉴意义。