Plexin C1/LIMK II/Cofilin-1信号通路在肺纤维化发病机制中的作用研究

Pulmonary Fibrosis is a chronic,progressive lung disease that etiopathogenisis and pathogenesis remain unknown and treatment is very limited.We have found that semaphorin 7A(sema 7A) plays an important role in the pathogenesis of pulmonary fibrosis,but the mechanism and pathway are not clear.Plexin C1 is one of the receptors for sema 7A.One of the downstream targets of plexin C1 is cofilin-1(CFL-1) whose activity can be regulated by phosphorylation.CFL-1 may also play an important role in the pathogenesis of pulmonary fibrosis.Some researchers have found that sema 7A can activate LIM kinase II(LIMK II) and regulate CFL-1 phosphorylation through plexin C1.So we hypothesize that sema 7A may modulate the pathogenesis of pulmonary fibrosis by regulating the phosphorylation status of CFL-1 through plexin C1 receptor and LIMK II.We aim to culture the peripheral blood fibrocytes of the Idiopathic Pulmonary Fibrosis（IPF） patients and normal control,establish bleomycin induced pulmonary fibrosis mouse model and TGF-β1 transgenic mouse model.Then detect the expression of CFL-1,phosphorylated cofilin-1（PCFL-1）,plexin C1 and LIMK II,the differentiation of the peripheral blood fibrocytes and the lung pathological changes of bleomycin induced pulmonary fibrosis mouse model and TGF-β1 transgenic mouse model before and after silencing plexin C1,LIMK II and CFL-1.Our aim is to clarify the role of plexin C1/LIMK II /CFL-1 signaling pathway in the pathogenesis of pulmonary fibrosis. Hopefully,through this research,we would give an insight into the pathogenesis of pulmonary fibrosis and explore a new therapentic target for it.

我们的前期研究发现semaphorin 7A(sema 7A)在肺纤维化的发病机制中起重要作用，但其确切机制不明。Plexin C1是sema 7A的受体之一，cofilin-1（CFL-1）是plexin C1的下游基因且可能参与肺纤维化的发病。有研究证实sema 7A能经plexin C1激活LIMK II而使CFL-1磷酸化。故我们推测sema 7A可能通过plexin C1调节CFL-1磷酸化而参与肺纤维化的发病机制。本研究拟通过培养IPF患者外周血纤维细胞、建立博来霉素致肺纤维化小鼠模型和TGF-β1转基因小鼠模型，检测阻断CFL-1各种通路前后CFL-1、PCFL-1、LIMK II、plexin C1的表达、纤维细胞的生长分化及小鼠肺纤维化的变化，探讨plexin C1/LIMK II/CFL-1通路是否参与肺纤维化的发病机制及其作用。为寻找肺纤维化新的治疗方法提供理论基础。

既往研究证实sema7A在肺纤维化的发病机制中起重要作用，CFL-1可能在肺纤维化中起重要作用，其活性受磷酸化调控。plexinC1是sema7A的受体之一，而CFL-1是plexinC1的下游靶点之一，plexinC1可以激活LIMK II而使CFL-1磷酸化从而失去其活性。但sema 7A是否通过Plexin C1/LIMK II/PCFL-1通路在肺纤维化中起作用目前不明确。本研究发现CFL-1促进肺纤维化，sema 7A可通过plexin C1调节CFL-1磷酸化而参与肺纤维化的发病机制。本研究发现在IPF患者和CTD-ILD患者的PBMCs中Plexin C1、LIMK II、PCFL-1的mRNA及蛋白表达水平较正常人下调，而CFL-1表达水平上调。体外培养人PBMCs，过表达CFL-1后促进纤维细胞的分化，而沉默CFL-1后抑制纤维细胞的分化。分别沉默Plexin C1、LIMK II后均能降低磷酸化CFL-1的表达水平，促进纤维细胞的分化，且下调PlexinC1后LIMK II水平下调。在博莱霉素致肺纤维化小鼠模型和TGF-β1过表达小鼠模型中发现Plexin C1、LIMK II、PCFL-1的mRNA及蛋白表达水平下调，而CFL-1表达水平上调。在两组肺纤维化小鼠模型中沉默CFL-1后小鼠肺纤维化减轻，分别沉默LIMK II、plexin C1后小鼠肺纤维化加重,且均能下调PCFL-1的水平，且下调PlexinC1后，LIMK II水平下调。这说明plexin C1通过plexin C1/LIMK II/PCFL-1通路参与肺纤维化的发病机制并起到抑制作用，而plexin C1为sema 7A的受体，sema 7A可能是通过plexin C1/LIMK II/PCFL-1通路而促进肺纤维化的发展的。此研究将为寻找肺纤维化新的治疗方法提供理论基础。