The Effects Of IGF-â…  And TGF-β₁ On The Pulmonary Fibrosis And The Intervention Of Simvastatin

Pulmonary fibrosis is not rare in clinic. For the unknown of its etiology and lacking valid treatment, most of patients died of respiratory failure. So it is necessary to study the pathogenesis and treatment of pulmonary fibrosis. To date, more attentions have been paid to the cytokines related to pulmonary fibrosis in the world. Former studies usually focused on only one cytokine's effect on pulmonary fibrosis. Nevertheless, in vivo, several types of cells and cytokines or the network between them are involved in the pathogenesis. The biological effects of these cells and cytokines interact each other. The study targets the coordinating function of two cytokines, IGF-Ⅰand TGF-β1, which are two important factors to pulmonary fibrosis. Meanwhile, the basic research on the efficiency of simvastatin to anti-pulmonary fibrosis is performed.The study includes the following two partsPart I IGF-Ⅰand TGF-β1 expression in lung tissue and model formation of rat with pulmonary fibrosis.Firstly, we made the animal model through the method that has been widely accepted using bleomycin to induce pulmonary fibrosis. The rats were divided into two groups, experimental group and control group. They were sacrificed respectively 1,2,3,4,weeks after bleomycin administration. The success of animal model was verified through H.E. staining and immunohistochemistry. The kinetic expressions of IGF-Ⅰand TGF-β1 were detected during model formation.Results of part IModel formationPulmonary tissue structures were normal in control group with H.E. staining. The sizes of alveolar cavities were uniform without effusion in them. In experimental group, the pulmonary interval widened and inflammatory cells infiltrated 1 week later. After 2 weeks, alveolar cavities became vanished and alveolar interval thickened markedly. The pathological changes in lung tissue were in accordance with pulmonary fibrosis after 4 weeks. Pulmonary interstitial fibers were found by VG staining. The animal model of pulmonary fibrosis was made successfully.Expression of IGF-Ⅰand TGF-β1 in rat lung tissue with pulmonary fibrosis1.In experimental group, IGF-Ⅰand TGF-β1 positive staining cells were located in pulmonary. There were no strong positive staining cells in control group.2.The expression of IGF-Ⅰand TGF-β1 was higher than that of control group, and there were excellent differences. (P﹤0.05)3.The expression of IGF-1 was increasing in the first, second, and third week, and decreased in the fourth week, however, there were marked differences between the first and the third week also between the first and the fourth week(P﹤0.05). 4.The peak of TGF-β1 expression was on the second week, and decreased during the third week. But its expression on the fourth week was also higher than that of the first week. Obvious differences were found between the first week and the second or the third week(P﹤0.05). Although decreased in the fourth week, the level of expression was still high.Part II Effect of IGF-Ⅰ, TGF-β1 and Simvastatin on HFL-1 cells proliferation and activationIn part I, we found that IGF-Ⅰand TGF-β1 take part in the formation of pulmonary fibrosis. Both of them regulate the development and progression of the disease. Following on, we studied the effect of IGF-Ⅰ, TGF-β1 and Simvastatin on HFL-1 cells proliferation and activation.Results of part IIThe effect of IGF-I and TGF-β1 on proliferation of HFL-1 cells1.IGF-Ⅰcould stimulate the proliferation of HFL-1 cells or TGF-β1 activated HFL-1 cells.2.IGF-Ⅰand TGF-β1 simultaneously acted on HFL-1 cells, the proliferation of cells were inhibited.The effect of IGF-Ⅰand TGF-β1 on the formation ofα-SMA and Procollagen-I in HFL-1 cells1.Both IGF-Ⅰand TGF-β1 induced Procollagen-I formation respectively without overlapping.2.TGF-β1 could induceα-SMA expression in HFL-1 cells, while IGF-Ⅰhad a weaker effect. As IGF-Ⅰand TGF-β1 worked together, the level ofα-SMA expression was less than that of TGF-β1 act alone.3.TGF-β1 could stimulate mRNA expression of IGF-Ⅰin HFL-1 cells. 4.TGF-β1 were needed for the activation of HFL-1 cells to expressα-SMA, otherwise, both IGF-Ⅰand TGF-β1 inhibited HFL-1 cells to expressα-SMA, which were activated by TGF-β1.Effect of IGF-Ⅰ,TGF-β1 and Simvastatin on cytobiological characters of HFL-1 cellsIGF-Ⅰand Simvastatin both acting on HFL-1cells could inhibit the cell proliferation, and TGF-β1 with Simvastatin (50μmol/L) could reduce the formation of Procollagen-I.The innovations of my studyThat the expression peak of IGF-Ⅰand TGF-β1 is not consistent was firstly identified domestically.The expression peak of IGF-I is behind that of TGF-β1, there is a little overlapping between them. These suggest that both IGF-Ⅰand TGF-β1 take part in the regulation of development and progress of pulmonary fibrosis and affect each other. TGF-β1 could inhibit HFL-1 cells proliferation that was stimulated by IGF-I. IGF-I could also inhibit HFL-1 activation and formation of Procollagen-I, which were stimulated by TGF-β1. These results suggest that IGF-I and TGF-β1 play roles in the process of pulmonary fibrosis, but have differences in pattern.TGF-β1 could stimulate mRNA expression of IGF-I in HFL-1 cells suggests that IGF-I could affect pulmonary fibrosis through autocrine pathway. Our study, in vitro, found that Simvastatin and IGF-I work on HFL-1 cells could inhibit cells proliferation. High concentration of Simvastatin act with TGF-β1 could induce formation of Procollagen-I.The study investigated the coordinate effect of IGF-I and TGF-β1 in pulmonary fibrosis and had new insight on how the two key factors affecting the process of pulmonary fibrosis. Meanwhile, the basic research on the efficiency of Simvastatin to anti-pulmonary fibrosis were performed and provided laboratory evidences for the new treatment to pulmonary fibrosis.