ABSTRACT
Objective To investigate whether thalidomide inhibits the over expression of type I collagen in pulmonary fibrosis rats via inhibiting the JNK signaling pathway,thereby reducing bleomycin induced pulmonary interstitial fibrosis in rats.Methods 90 healthy male SD rats were randomly divided into normal control group (group N),model group (group M),thalidomide group (group T),SP600125 group (group SP) and thalidomide+SP600125 group (group T+SP).The pulmonary fibrosis models were prepared via intratracheal injection of 5mg/kg bleomycin,and rats in groups were given corresponding drugs from the first day after preparing model.Rats were randomly sacrificed at 7,14 and 28 days after treatment.The degree of pulmonary alveolitis and fibrosis was evaluated by H&E and trichrome masson stainings.The level of hydroxyproline in the lung tissue was detected by applying alkaline hydrolysis technique,and expression levels of p-JNK and type I collagen were tested by Western bloting for protein expression and real-time polymerase chain reaction (RT-PCR) for mRNA expression.Results In group M,alveolitis was the most serious on day 7; a marked pulmonary fibrosis formed on day 28; the level of hydroxyproline also peaked on day 28,and the contents of p-JNK and type I collagen were higher than in group N(F=277.87,472.51,both P＜ 0.01).Group T,SP and T+SP showed mild alveolitis and fibrosis at all time points,and their levels of hydroxyproline,p-JNK and type I collagen were remarkably decreased as compared with group M (F=14.77,61.59,101.73,all P＜0.01;F=10.33、79.12、57.48,all P＜0.01).No significant difference in p JNK was found between group SP and group T+SP.Conclusions Thalidomide may inhibit the over expression of type I collagen in pulmonary fibrosis rats via inhibiting the JNK signaling pathway,thereby reducing bleomycin induced pulmonary interstitial fibrosis in rats.