低氧诱导因子-1α在慢性阻塞性肺疾病上皮-间质转化中的作用及机制研究

So far, the molecular and cellular mechanisms for chronic obstructive pulmonary disease(COPD) are not well understood, and lack of effective prevention and treatment methods for COPD. Epithelial–mesenchymal transition(EMT) is the most important pathophysiological character of COPD, and may lead to weakened pulmonary function, pulmonary fibrosis, even meeting canceration. As an improtant transcription factor, hypoxia inducible factor-1α(HIF-1α) plays important roles in hypoxia and inflammation through regulates its target genes. In addition to hypoxia, inflammation is the most important factor that induced HIF-1α activity. Studies about the roles and mechanisms of EMT in COPD were very scarce. In our previous study, we found that collagen deposition was incerased in COPD lung tissue, and the levels of epithelial cells marker proteins were decreased and mesenchymal cells marker proteins were increased significantly in COPD lung tissue. In addition,we found that HIF-1α protein level was increased in lung tissue of COPD. In combination with related literature, we speculate that HIF-1α very likely play important roles in the development and progress of EMT in COPD. This research will take mainly HIF-1α transgenic mice as test subjects, further investigate the role and mechanism of HIF-1α in EMT of COPD. In addition, the role and mechanism of HIF-1α inhibitor digoxin in prevention development and progress of EMT in COPD will also been studied in this research. The research will gain more insight into mechanism of COPD, and provide some new ideas on searching potential target and improving treatment of COPD.

慢性阻塞性肺疾病（COPD）发病机制目前仍不完全清楚，缺乏有效的防治手段。上皮-间质转化（EMT）是COPD的重要病理生理特征，是导致肺功能下降、肺纤维化甚至发生癌变的重要原因。作为一种核心转录因子，低氧诱导因子-1α（HIF-1α）通过调节下游靶基因在炎症或低氧条件下发挥重要作用，但目前对HIF-1α在COPD发生EMT中的作用及分子机制研究十分匮乏。我们在前期研究中发现，COPD模型小鼠肺组织胶原沉积量明显增加，上皮细胞标志蛋白表达水平降低而间质细胞标志蛋白表达水平增加，同时HIF-1α在COPD模型小鼠肺组织中表达水平明显升高。本课题将主要以HIF-1α转基因小鼠为研究对象，应用分子生物学和病理学等方法继续深入研究HIF-1α在COPD发生EMT中的作用及具体机制，本课题将有助于加深对COPD发病机制的认识，为寻找新的防治靶点、改进治疗方法提供理解依据。

慢性阻塞性肺疾病（COPD）发病机制目前仍不完全清楚，缺乏有效的防治手段。上皮-间质转化（EMT）是COPD的重要病理生理特征，是导致肺功能下降、肺纤维化甚至发生癌变的重要原因。作为一种核心转录因子，低氧诱导因子-1α（HIF-1α）通过调节下游靶基因在炎症或低氧条件下发挥重要作用，但目前对HIF-1α在COPD发生EMT中的作用及分子机制研究十分匮乏。本课题主要以HIF-1α转基因小鼠（HIF-1α+/-）为研究对象，建立HIF-1α+/-小鼠COPD模型，应用分子生物学和病理学等方法，继续深入研究HIF-1α在COPD发生EMT中的作用及具体机制，同时探讨HIF-1α抑制剂地高辛对COPD发生EMT的干预作用及机制。本研究前期成功建立了HIF-1α+/-及其对照小鼠（HIF-1α+/+）的COPD模型，并用地高辛进行干预。结果表明：1.HIF-1α可促进COPD的发生发展；2.地高辛有助于保护烟草烟雾诱导的COPD小鼠的肺功能；.3.地高辛能够减轻烟草烟雾诱导COPD小鼠的肺气肿程度；4.地高辛能够减轻烟草烟雾诱导COPD小鼠的肺部慢性炎症；5.地高辛能够减轻烟草烟雾诱导COPD小鼠的大气道的粘液分泌。通过进一步研究HIF-1α抑制剂地高辛对COPD肺组织EMT中的作用，我们发现：1.地高辛对COPD小鼠肺组织EMT相关蛋白Fibronectin、Vimentin有明显的抑制作用；2.地高辛抑制烟COPD小鼠肺组织TGF-ß、smad1及smad3的mRNA水平；3.地高辛抑制烟草烟雾提取物暴露导致A549细胞上皮间质转化；4.地高辛抑制烟草烟雾提取物暴露导致A549细胞TGFβ1\Smad3mRNA水平的表达；5.地高辛抑制烟草烟雾提取物暴露导致A549细胞培养液白介素等炎症因子释放。综上，本课题首次证明：1. HIF-1α促进COPD上皮间质转化，地高辛作为HIF-1α抑制剂可以抑制上皮间质转化的发生；2. HIF-1α参与COPD上皮间质转化可能是通过HIF-1α\TGF-β1\ Smad3信号通路。本课题基本明确了HIF-1α对COPD肺组织上皮间质转化的调控作用，为寻找治疗COPD的粘液高分泌及上皮间质转化提供了新的靶点和理论依据。