石英粉尘引起的肺组织纤维化是矽肺的主要病理改变，肺泡上皮细胞向间质细胞转化(EMT)是肺纤维化成纤维细胞的重要来源。已有研究表明骨形态发生蛋白-7(BMP-7)具有逆转EMT的作用，但机制不清。本课题组前期研究发现TGF-β信号通路可能参与了石英诱导的肺泡II型上皮细胞发生EMT的过程。本研究在此基础上拟通过建立石英诱导的EMT细胞模型，观察TGF-β信号通路(Smad和MAPK)在EMT中的变化特点；通过建立BMP-7基因过表达和沉默的细胞模型，探讨BMP-7拮抗TGF-β信号通路(Smad和MAPK)的作用机制；通过建立石英诱发的大鼠矽肺模型，采用BMP-7干预治疗，研究EMT、肺纤维化进展、TGF-β下游信号通路(Smad和MAPK)三者的关系。本课题拟从分子、细胞、整体水平证实我们的假说：BMP-7可能通过拮抗TGF-β信号通路（Smad和MAPK）发挥预防和延缓矽肺纤维化的作用。

Pulmonary fibrosis is the main pathological change of silicosis induced by silica dust. Pulmonary epithelial-to-mesenchymal transition(EMT) is one important source of fibroblasts in the pulmonary fibrosis. Studies have shown that BMP-7 could reverse EMT, but the mechanism is not clear. Our previous work demonstrated that TGF-β signaling pathway may be involved in EMT of type II alveolar epithelial cell treated with silica. This study on this base is to observe the change characteristics of TGF-β signal pathways(Smad and MAPK) in the EMT process through establishing EMT cell model induced by silica. The mechanisms of BMP-7 antagonizing TGF-β signal pathways(Smad and MAPK) are going to be explored through the establishment of cell models of BMP-7 gene overexpression and silence. In vivo animal studies, BMP-7 will be administered to rats with pulmonary fibrosis induced by silica to investigate the mutual relationship among EMT, pulmonary fibrosis progression and TGF-β downstream signal pathways(Smad and MAPK). This subject will confirm our hypothesis in cellular, molecular and whole levels that BMP-7 could prevent and delay pulmonary fibrosis caused by occupational exposure to silica dust through antagonizing TGF-β signal pathways(Smad and MAPK).