The Expression and Significance of Connective Tissue Growth Factor in Fibrotic Lung Tissue of Patients with Idiopathic Pulmonary Fibrosis

Objective:To investigate the expression and significances of connective tissue growth factor in fibrotic lung tissue of patients with idiopathic pulmonary fibrosis(IPF).Methods:Fibrotic lung tissue specimens were obtained from a total of 35 patients with IPF by transbronchial lung biopsy(TBLB),30 normal lung specimens obtained from resection of thoracic surgery were used as controls.To investigate the expression of CTGF messenger ribonuclear acid(CTGF mRNA) and its protein using in situ hybridization and immunohistochemical staining respectively through comparing distribution grade in various cells(score) and positive proportion percentage.To investigate fibronection(Fn) expression using immunohistochemical staining through comparing positive proportion percentage.The correlation with the positive proportion percentage of CTGF mRNA and its protein and that of Fn were further analyzed.Results:(1)The positive proportion percentage of CTGF mRNA and its protein and Fn were significantly elevated in fibrotic lung tissue in patients with IPF compared to nomal lung tissue(P0.001);(2)CTGF mRNA and its protein were confined predominantly to proliferating type Ⅱ alveolar epithelial cells,fibroblasts and alveolar macrophages in fibrotic lung tissue in patients with IPF(P0.001).The distribution of them in tiny bronchial epithelial cells were found have no difference in two groups(P0.05).(3)The rank correlation coefficient of positive proportion percentage of CTGF mRNA and its protein with that of Fn was 0.51 and 0.64 respectively(P0.01) in fibrotic lung tissue of patients with IPF.Namely the expression of CTGF mRNA and its protein were found to have a close positive correlation with that of Fn in fibrotic lung tissue of patients with IPF.Conclusions:In the present study,we have shown that CTGF mRNA and its protein were expressed at a high level in fibrotic lung tissue of patients with IPF.The immunolocalization of CTGF was confined predominantly to proliferating type II alveolar epithelial cells,fibroblasts and alveolar macrophages.The expression of Fn was elevated in fibrotic lung tissue of patients with IPF.A positive correlation was found between the expression of CTGF and Fn.We suspected that connective tissue growth factor(CTGF) may play a critical role in pulmonary fibrosis by producing fibronection(Fn) in IPF.