| ABSTRACTBackground and Objective: Idiopathic pulmonary fibrosis(IPF) is characterized by the alveolar epithelial cell injury,abnormal tissue repair,the excessive proliferation of fibroblasts,deposition of extracellular matrix(ECM) and lung structure remodeling.These result to pulmonary fibrosis,pulmonary function decline,respiratory failure and serious consequences.The pathogenesis of pulmonary fibrosis remains unknown.IPF has a high morbidity and mortality, and is lack of effective treatment.Plasminogen activator inhibitor-1(PAI-1)is one of the serine protease inhibitor,it is an important inhibitor of fibrinolytic system activation.It can inhibit the activity of u PA and t PA.The compound of PAI-1 and vitronectin are the major component of the extracellular matrix(ECM).The expression of u PA and PAI-1 is balanced in normal alveoli.UPA can remove the fibrin.The expression of PAI-1 is increase,while the the expression of the u PA is decreased when the lung tissued injured.The fibrin cannot be degradated because of the balance of fibrinolytic system is discrupted.This is an important reason of pulmonary fibrosis.Peroxidase proliferation-activated receptor gamma(PPARγ) is a kind of transcription factor that can be activated by PPARγ agonists.Rosiglitazone(RSG) is a synthetic ppar-gamma ligands.Over the past decade,it’s reported that rosiglitazone can increase insulin sensitivity,and reduce insulin resistance in the treatment of diabetes.In addition to,the rosiglitazone has very strong anti-inflammatory effects. A growing body of evidence suggests that rosiglitazone is effective in the treatment of tissue fibrosis.In the treatment of renal fibrosis,Ppar-gamma agonist rosiglitazone can suppress the expression of PAI-1.It’s reported that rosiglitazone play a role in the treatment of lung fibrosis.The molecular mechanism of rosiglitazone in the treatment of pulmonary fibrosis remains unclear.Rosiglitazone play a role in the treatment of pulmonary fibrosis.The mechanisms include preventing the proliferation of fibroblasts, reducing the inflammation reaction,decreasing the thickeness of basement membrane,increasing cell apoptosis conversion and derease the deposition of extracellular matrix.In our study,we explore whether rosiglitazone can inhibit the process of pulmonary fibrosis,and whether the signal mechanism by the modulation the fibrinolytic system.Methods:A total of 54 healthy male wistar rats(provided by Experiment Animal of Hebei Medical University) weighed 120-130 g were divided into three groups with random number table:control group,BLM group(B),and BLM+RSG group(B+R).There were18 rats in each group.Abdominal cavity anesthesia was performed by 10% chloral hydrate(3 ml/kg).The rats were fixed in supine position,the neck skins were disinfect,the middle of the neck skins were cut, the tissues were separated,tracheas were expose.Lung fibrosis models were induced by intratracheal injection BLM(5mg/kg) 0.2~0.3ml in B and B+Rgroups,while equal volume 0.9% Na Cl were injected into trachea in control group.After 24 hours B + R group was lavaged with rosiglitazone in 3 mg/kg everyday,other two groups were lavaged with equal volume 0.9% Na Cl. 6 rats were sacrificed on 7d,14 d and 28 d in each group.Middle lobe of right lung was fixed by 4% paraformaldehyde,for histological examination(HE staining to observe the histologic changes,Masson staining to observe the pulmonary fibrosis degree);superior lobe of right lung were stored at-80℃for Real time PCR to determine the relative concentration of PAI-1,u PA and PPARγ m RNA in lung tissue.Right lower lung were stored at-80 ℃for Western blot to determine the relative protein expression of P-AKT. Alveolitis and pulmonary fibrosis were determined by the method of Szapiel. Statistical analysis of values was performed with SPSS13.0 software.Results:1 The results of pulmonary pathology:on 7d,14 d and 28 d,the degree of alveolitis of group B was more serious than that of the control group,(P<0.05).The level of fibrosis became obvious on 14 th day in group B,and group B was more serious than that of the control group(P<0.05)on the 14 th day and 28 th day.After the treatment of RSG,the level of alveolitis and the degree of fibrosis in group B+R was ameliorated than that in group B on 7th day,14 th day and 28 th day(P<0.05).2 Real time PCR results: The expression of PAI-1 m RNA in group B was Higer than that in the control group(P<0.05)on each time point.After the treatment of RSG,the expression of PAI-1 m RNA in group B+R was lower than that in the group B on each time point.The expression of u PA m RNA and PPARγ m RNA in group B was lower than that in the control group on 7th day, 14 th day and 28 th day(P<0.05).After the treatment of RSG,the expression of u PA m RNA and PPARγ m RNA in group B+R was lower than that in the control group on 7th day,14 th day and 28 th day(P<0.05).3 Western blot results:The expression of P-AKT protein in group B was higher than that in the control group on each time(P<0.05).After the treatment of RSG,the expression of P-AKT protein in group B+R was lower than that in the group B on 7th day,14 th day and 28 th day(P<0.05).Conclusions:1 Rosiglitazone has an effect on bleomycin-induced lung fibrosis in rats.2 In the process of pulmonary fibrosis,the expression of PAI-1 is increased,the u PA expression is decreased,and the fibrinolytic system is restrained.After PPAR gamma is activated,the expression of PAI-1 is decreased,the u PA expression is increased,and the fibrinolytic system is activated.3 Pehaps the cross-talk between PAI-1 and P-AKT signaling pathways plays an important role in rosiglitazone treatment on pulmonary fibrosis. |
