Caveolin-1低表达介导的巨噬细胞M2极化在系统性硬化症肺纤维化发生发展中的作用及相关机制研究

Pulmonary fibrosis is the most frequent complication of systemic sclerosis (SSc) with the worst prognosis, which has posed great threat on patients’ lives and health. Recent studies have indicated that macrophage M2 polarization could play a critical role in the onset and progression of pulmonary fibrosis in SSc patients, however, it is still unknown how macrophage M2 polarization is triggered. It has been found that caveolin-1 (Cav-1) expression level are very low in SSc patients and mice deficient for Cav-1 develop spontaneous pulmonary fibrosis similar to SSc patients. In our early studies, we have found that Cav-1 deficiency can promote macrophage M2 polarization, which raises the possibility that Cav-1 could accelerate the process of pulmonary fibrosis by promoting macrophage M2 polarization. Based on these findings, the current project is dedicated to perform the following studies: 1) to investigate the molecular mechanisms of accelerated macrophage M2 polarization by Cav-1 deficiency; 2) to clarify the roles of Cav-1 KO M2 macrophages in the development of pulmonary fibrosis; 3) to explore the relationship between Cav-1 expression, macrophage M2 polarization and the disease evolution of the SSc patients with pulmonary fibrosis, with a purpose to identify novel biomarkers with predictive and prognostic values. Collectively, this project will not only provide critical information to help to dissect the underlying mechanisms to the onset and progression of lung fibrosis in SSc patients, but also harbor the potential to provide novel clues to facilitate the prevention and treatment of this severe disease.

肺纤维化是系统性硬化病（SSc）最常见且预后最差的并发症，严重威胁患者的生命健康。近期的研究发现巨噬细胞M2极化在SSc肺纤维化过程中发挥了重要作用，但巨噬细胞发生M2极化的具体机制尚不清楚。SSc患者体内小窝蛋白1（Cav-1）表达水平极低而Cav-1基因缺失的小鼠可发生与SSc患者相似的肺纤维化；而我们的前期工作发现Cav-1缺失可促进巨噬细胞发生M2极化，提示Cav-1可能是通过促进巨噬细胞M2极化进而促进肺纤维化。在上述工作的基础上，本项目拟开展如下研究: 1) 研究Cav-1缺失促进巨噬细胞M2极化的分子机制；2) 明确Cav-1 KO M2型巨噬细胞在鼠肺纤维化形成中的作用；3) 明确Cav-1和M2巨噬细胞与SSc 肺纤维化患者病情的相关性，寻找具有预测和预后价值的生物学标志物。本研究不但对于阐明SSc 肺纤维化形成的机制有着重要的意义，而且也可为肺纤维化的诊治提供新的线索。

背景：.结缔组织病是一组由自身免疫异常介导的炎症性疾病，间质性肺病是结缔组织病常见并发症之一。结缔组织病患者合并间质性肺病会不仅会严重影响生活质量，并且会对患者的预后产生重大影响。巨噬细胞作为对纤维化过程有重要影响的先天免疫细胞，可在受到刺激之后活化，巨噬细胞向M2极化可促进肺纤维化。Caveolin-1（Cav-1）在巨噬细胞极化过程中被证明发挥重要作用。microRNA可调节基因表达，microRNA199a/b被发现可影响Cav-1表达水平。本研究旨在研究microRNA199a/b对巨噬细胞极化的作用以及对肺纤维化发病的影响，探索抗纤维化治疗的新方向。.主要研究内容：.我们首先在细胞水平验证了microRNA199a/b对巨噬细胞极化的影响。将小鼠腹腔巨噬细胞利用lipofectamine RNAiMAX Reagent转染试剂进行microRNA199a/b agomir转染，然后加入IL-4诱导巨噬细胞向M2方向极化，观察microRNA199a/b agomir转染之后的巨噬细胞对IL-4诱导的反应。然后我们在小鼠模型上试验了microRNA199a/b antagomir对肺纤维化的影响。对博来霉素诱导的肺纤维化小鼠通过尾静脉注射microRNA199a/b antagomir，观察其是否有治疗效果。.重要结果：.在细胞水平上我们观察到microRNA199a/b agomir转染巨噬细胞可以促进其向M2方向极化。同时我们在小鼠模型上发现尾静脉注射microRNA199a/b antagomir可以减轻博来霉素诱导的小鼠肺纤维化。.结论：.上调microRNA199a/b水平可以通过抑制Cav-1表达从而促进巨噬细胞向M2极化，进而导致肺部纤维化的发生，而下调microRNA199a/b水平可以减少肺纤维化的发生。