Study On Mechanism Of Rho/Rock Signal Transduction Pathway In Lung Tissues Of Mice With Pulmonary Fibrosis And The Intervention

Objective To determine the expression and significance of Rho Associated Kinase-1 in lung tissues of mice with pulmonary fibrosis(PF) induced by bleomycin at various periods and to study the effects of Rho/Rock signal transduction pathway on pulmonary fibrosis.Methods According to the random number table,all 100 mice were randomly divided into 5 groups,of which there were four model groups of pulmonary fibrosis. Fibrosis model was established by intratracheal injection of bleomycin(5mg·kg^-1). Theses four goups were respectively BLM group,DXM group,FAS group,FAS+DXM group,each of which contains 20 mice.After molding an hour,the 3 groups ranked behind were administered dexamethasone(DXM,5mg·kg^-1·d^-1 0.1ml), FAS(15mg·kg^-1·d^-1 0.3ml),FAS+SSd(0.28ml) respectively by intraperitoneal injection(ip) once daily up to the 28^th day.BLM group were administered normal saline(ip).In addition,there 20 mice in the normal control group(Cont group) was administered normal saline also by intraperitoneal injection at the same time in the same way.The mice were anesthetized and sacrificed at the 3^th 7^th,14^th,28^th day for lung tissue,and we observated the conventional histopathological change of the lung tissue,hydroxyproline(HYP) were lung tissue samples。Immunohistochemistry were used to detect the expression of alpha-smooth muscle actin(α-SMA) and E-cadherin..Western Blotting were used to detect the expression of rock-1.Results(1)In the Cont group,after the investigation of histopathology of the lung tissues,inflammatory cell infiltrates,and Alveolar inflammatory exudate was rarely to be found,meanwhile,without finding Alveolar septum thickening,the proliferation of fibroblast and remarkable alterations of PF.Dynamic changes range from alveolitis to pulmonary fibrosis could be observed in the slices by pathological method according to times;In the early stage,Alveolar inflammatory exudate was heavier,there were a large number of inflammatory cells infiltration in the alveolar wall.In the middle and Late stages,Inflammatory exudate can be seen gradually reduced,alveolars collapsed and disappeared,vary in size,alveolar septum became thicken gradually,A large number of proliferating fibroblasts could be seen.In the BLM group alveolitis and lung fibrosis scores were higher than the Cont group and the DXM group,there were statistically significant(P＜0.05);In the DXM group,dynamics of changes from alvealitis to pulmonary fibrosis can be seen in the pathological examination,but alveolitis and pulmonary fibrosis in the DXM group is lighter than the BLM group.(2) The index HYP of BLM group in lung tissue begin to ascend on the 7^th day, and get peak value on the 28^th day;on the 28^th day,compaired with BLM group,there was a significant difference in DXM group.(3) Compared to those in the Cont group,the protein level ofα-SMA was significantly increased in the BLM group and DXM group.while the protein level of E-cadherin was decreased significantly.(4)The expressions of rock-1 and Mypt-1protein in lung tissues in BLM group were higher than those in Cont group(P＜0.05),the expression of rock-1 protein were higher in BLM group from the third day,the peak was observed on the 14th day, and the expression was decreased on the 28th day.while the protein level of Rock-1 and Mypt-1 in DXM group was decreased significantly.(5) Compared with DXM group and FAS group,the Rock-1 of FAS+DXM group decreased significantly.(6) the Rock-1 of DXM group,FAS group decreased significantly.The Rock-1 of FAS group decreased faster than the Rock-1 of DXM group.There is significance of Rock-1 in lung tissue between the two therapeutic groups.Conclusion The expression of rock-1 is positively correlated with the degree of pulmonary fibrosis,which probably suggests that Rock-1 is a promoter to pulmonary fibrosis via the induction of epithelial-mesenchymal transition..Fasudil could have obvious therapeutic effects on Bleomycin-induced pulmonary fibrosis in mice.The therapeutic efficacy of using fasudil and dexamethasone is better than using either fasudil or dexamethasone.