Etanercept attenuates bleomycin-induced lung fibrosis in mice

AIM: To evaluate the effect of tumor necrosis factor α (TNF-α) antagonist etanercept on bleomycin-induced lung fibrosis in mice.METHODS: Forty-five Kunming female mice were randomly divided into 3 groups: the mice in control group were intraperitoneally injected with vehicle and intratracheally administered with saline aerosol, the mice in bleomycin group were intraperitoneally injected with vehicle and intratracheally administered with bleomycin (3 mg/kg) aerosol, and the mice in bleomycin+etanercept group were intraperitoneally injected with etanercept (4 mg/kg) every 3 d and intratracheally administered with bleomycin aerosol. All animals were sacrificed 28 d after treatments. The left lung was fixed in 10% neutral formalin and then stained with hematoxylin-eosin or Masson’s trichrome for the pathological examination. The tissues of right lung were sampled for measuring the content of hydroxyproline (HYP) by the method of alkaline hydrolysis. The serum concentrations of TNF-α and TGF-β were detected by ELISA. Total tissue protein was extracted for examination of ERK1/2, JNK and p38 by Western blotting.RESULTS: Etanercept prevented the collagen accumulation under the airway epithelium and decreased the scores of lung inflammation and fibrosis induced by bleomycin with significantly reduced the levels of tissue HYP, serum TNF-α and serum TGF-β. The protein phosphorylations of ERK/JNK/p38 in the lung tissues were remarkably decreased compared with BLM group.CONCLUSION: Etanercept decreases the phosphorylations of ERK1/2/JNK/p38 via inhibiting the expression of TNF-α and TGF-β. Etanercept might be useful in the treatment of pulmonary fibrosis.