The Role of N-acetylcysteine in Suppressing Bleomycin-induced Pulmonary Fibrosis in rats

Objective To investigate the role and mechanism of N-acetylcysteine in suppressing bleomycin-induced pulmonary fibrosis in rats.Methods One hundred SD rats were randomly divided into four groups(25 rats in each group):normal group,bleomycin-induced pulmonary fibrosis model group,dexamethasone-treated group,and N-acetylcysteine-treated group.Five rats in each group were randomly killed on the 1st day,3rd day,7th day,14th day and 28 th day,respectively,and lung tissue samples were harvested for histopathology study.HE and Masson staining were used to determine the extent of alveolus inflammation and pulmonary fibrosis,respectively.Histoimmunochemical staining was used to determine the protein levels of transforming growth factor-β1(TGF-β1).Serum and bronchoalveolar lavage fluid(BALF) were harvested to determine the protein levels of transforming growth factor-β1(TGF-β1)by ELISA,lung tissue samples were harvested to determine the concentration of hydroxyproline(HYP).Results Histopathological study showed that treatment with either dexamethasone or N-acetylcysteine remarkably meliorated the extent of alveolus inflammation and suppressed pulmonary fibrosis(compared with model group,P 0.05).Histoimmunochemical study suggested that both dexamethasone and N-acetylcysteine inhibited the expression of TGF-β1(compared with model group,P 0.05),there was the same tendency of changes in serum and bronchoalveolar lavage fluid(BALF)as that in the tissue,and the suppression of TGF-β1 was more obvious in N-acetylcysteine-treated group than those in dexamethasone-treated group(P 0.05).The treatment with either dexamethasone or N-acetylcysteine remarkably reduced contents of hydroxyproline(HYP)in lung tissue(compared with model group,P 0.05),and the suppression of contents of hydroxyproline(HYP)was more obvious in N-acetylcysteine-treated group than that in dexamethasone-treated group(P 0.05).Conclusions N-acetylcysteine has potent anti-fibrosis effect similar to dexamethasone.Such effect may result from inhibition of the cytokine TGF-β1