Expressions of platelet derived growth factor and plaminogen activator inhibitor-1 in lung tissue of pulmonary fibrosis rats induced by bleomycin

Objective To study the expression of platelet derived growth factor and plaminogen activator inhibitor-1 in lung tissue of pulmonary fibrosis models induced by bleomycin in rat,and discuss the possible mechanism.Methods Thirty Wistar rats were randomly divided into two groups(15 in each group),bleomycin group(BLM group)and control group(NS group).①BLM group was intratracheally instilled with belomycin(BLM)(5 mg/kg)for pulmonary fibrosis.②NS group was intratracheally instilled with saline(5 mg/kg).Five rats in each group were sacrificed at 7.14,and 28 days after intratrachel instillation,BALF of right lung was taken for cell classification and calculation.Collagen content of the left lung tissue was assessed by hydroxyproline concentration.The expressions of PDGF and PAI-1 protein were assessed by immunohistochemistry.Results ①The collagen in BLM group significantly increased compared with that in NS group at day 7(P＜0.01);at day 14 and 28 the collagen continued to elevate.and there was significant difference compared with that in NS group(P＜0.01);②the expression of PDGF protein in BLM group after administraton of bleomycin was the highest at day 7 and then declined,but still elevated over NS group at day 2 8(P＜0.05);the expression of PAI-1 protein was significantly increased in BLM group at day 7.and was the highest at day 28.The expession was correlated with the collagen of lung(r=0.952,P＜0.01).Conclusions The deposition of collagen in lung might be the mechanism of PDGF and PAI-1 protein leading to pulmonary fibrosis. Key words: Pulmonary fibrosis; Bleomycin; Platelet derived growth factor; Plaminogen activator inhibitor-1; Collagen