Objective: To study the roles of fibronectin (FN) played in rat pulmonary fibrosis.
Methods: The dynamic change of FN was observed in bleomycin-induced rat pulmonary fibrosis using immunohistochemical technique. Northern blot analysis and immunocytochemistry techniques were performed to detect the expression of type I, III procollagen mRNA and their relevant proteins in cultured rat pulmonary fibroblasts (PFbs) after FN treatment.
Results: (1) The pulmonary tissue of rats which received bleomycin showed continuously strong positive reaction with anti-FN. (2) The expression of type I, III procollagen mRNA in rat PFbs enhanced at 2 h after FN treatment, and reached their peaks at 6 h, 12 h respectively. The expression of type I, III procollagen proteins detected by immunocytochemistry was also increased after the FN treatment (P < 0.01). Anti-integrin alpha(5) monoclonal antibody could partially inhibit the effect of FN on enhancing the expression of type I, III procollagen in PFbs (P < 0.05).
Conclusions: FN could up-regulate the synthesis of type I, III procollagen mainly by enhancing the transcriptions of procollagen genes.