Expression And Significance Of Connective Tissue Growth Factor In Bleomycin Induced Pulmonary Fibrotic Rats

Background and Objective: The pathogenesis of pulmonary fibrosis is complicated, it is characterized with myofibroblast hyperplasia and deposition of collagen protein. Study demonstrated that the pathogenesis is associated with disorders of all kinds of cytokines or growth factors. Connective tissue growth factor(CTGF), which is a downstream cytokine of transforming growth factor- 1 (TGF- 1), may be a critical cytokine in the development of bleomycin-induced pulmonary fibrosis in rats. This experiment is to investigate the expression and significance of CTGF in bleomycin-induced pulmonary fibrotic rats.Materials and Methods: In this study, 42 rats were divided into two groups: control group, model group in random.On experimental day(dayO), the rats were intratracheally instilled with bleomycin(5mg/kg body weight)or sterile saline.On day 7, 14, 28 after instillation, 7 rats of each group were sacrificed and the lung tissues were harvested for histopathological examination.The expression of CTGF mRNA, TGF-, Tumor necrosis factor -alpha(TNF- ), fibronectin(FN), Collagen-1 *, III were measured by using in situ hybridization or SABC immunohistochemical technique.Results: (l)The degrees of alveolitis and pulmonary fibrosis of model group were increased remarkably on day 7, 14, 28 compared with control group (P<0.05); (2) The expression of CTGF mRNA of model group was higher than of control group on day 7, 14, 28 (P<0.05); (3) The expression of TGF- 1 protein of model group on day 7,14, 28 was remarkably increased compared with control groups (P<0.05); (4) The expression of TNF- protein of model group on day 7, 14, 28 was remarkably increased compared with control group (P<0.05); (5) The expression of FN protein of model group on day 7, 14, 28 was remarkably increased compared with control group (P<0.05); (6) The collagen I , III protein expression of model groupon day 7, 14, 28 were remarkably increased compared with control group (P<0.05). Conclusion: The expression of CTGF mRNA in lungs of rats with pulmonary fibrosis by bleomycin-induced was remarkably up-regulated.As a downstream cytokine of TGF- 1, CTGF may play an important role in the development of the pulmonary fibrosis in bleomycin-induced fibrotic rats through promoting the synthesis of ECM, which will provide a new idea for us.