COPD细胞外基质失调对支气管上皮细胞EMT的影响及整合素αVβ6/αVβ8在其中的作用

Chronic obstructive pulmonary disease (COPD) leads to a huge economic and social burden, and the available therapies cannot effectively slow disease progression. Aberrant extracellular matrix (ECM) deposition in small airway wall and epithelial remodeling play an important role in the development of COPD. Fibroblasts are known to be the main source for ECM. Our preliminary study suggests that primary human lung fibroblasts from COPD patients showed a profibrotic profile, but the growth capacity was weakened; moreover, conditioned medium of fibroblasts exposed to tobacco combustion stimulation was capable of inducing epithelial-mesenchymal transition (EMT). These findings, together with the most recent results from the studies on pulmonary fibrosis, prompt the hypothesis that abnormal ECM as a whole (matrisome) might induce EMT of bronchial epithelial cells, leading to epithelial remodeling via a positive feedback loop between fibroblasts, aberrant ECM and epithelial cells. The details in such profibrotic circle and its mechanism is unknown. The current project is aimed to extract decellularized ECM and reproduce fibroblast-ECM-epithelial COPD models. The impact of abnormal ECM on EMT in small airways is to be investigated in patients with COPD, animal model and in vitro cell cultures. Integrin αVβ6 and αVβ8, which is expressed mainly on epithelial cells as ECM receptors, are hypothesized to play a key role in ECM induced EMT. To verify this hypothesis, the expression of integrin αVβ6 /αVβ8 and its relationship with EMT and aberrant ECM is to be observed. In animal and cell COPD models, molecular tools including siRNA knockdown and overexpression are to be used to clarify its mechanism of action including TGF-β1 and signal transduction pathway. The data from these studies will help to develop new therapeutic targets for small airway remodeling in COPD.

小气道壁细胞外基质（ECM）异常沉积和上皮重塑在慢性阻塞性肺疾病（COPD）的发生发展中起着重要作用。成纤维细胞异常活化是ECM 过度沉积的主要原因，课题组前期研究提示COPD 患者肺成纤维细胞虽然有促纤维化的高分泌特征，但增殖功能减弱；烟草燃烧物刺激后的成纤维细胞培养液能诱发上皮细胞间充质转化（EMT），提示异常ECM可能通过诱发支气管上皮细胞EMT维持促纤维化正向循环，但机制不明。本项目拟从COPD患者和动物模型中提取脱细胞ECM，从人体、动物、细胞三个层面建立肺成纤维细胞-ECM-支气管上皮细胞实验平台，研究ECM对COPD小气道EMT的作用及其影响因素；通过siRNA等多种分子手段，明确整合素αVβ6 、αVβ8是否为异常ECM所致上皮EMT中的关键上皮细胞受体，及其TGF-β1作用机制和可能的信号转导通路，期望阐明COPD小气道重塑的始动机制，为开发新治疗靶点提供依据。

小气道壁细胞外基质（ECM）异常沉积和上皮重塑在慢性阻塞性肺疾病（COPD）的发生发展中起着重要作用。我们研究了COPD肺成纤维细胞及异常ECM诱发上皮细胞EMT的作用及其影响因素。同时还研究了ECM及整合素的代谢产物PICP 和 ICTP水平与稳定期慢阻肺患者气道重构的关系以及筛选出多个与慢阻肺肺气肿发生的候选基因。发现PICP与稳定期慢阻肺患者气道重构情况相关，并且炎症因子在调控ECM及整合素的生成释放中发挥关键作用；慢阻肺患者气道的ECM和整合素αVβ6表达处于紊乱状态；成纤维细胞分泌ECM的培养基(FCM)可以促进气道上皮细胞的EMT，但是上皮细胞过度增殖导致与成纤维细胞接触时，便失去了成纤维细胞分泌细胞因子对其的保护作用。上述研究进一步阐释了COPD小气道重塑的始动机制，为开发新治疗靶点提供依据。