Abstract: Objective To investigate the mechanism ofTanshinone IIA in treating with pulmonary fibrosis in mice. Methods A549 cells and Bleomycin induced pulmonary fibrosis mice were divided into control group, pulmonary fibrosis model group and Tanshinone IIA group, observe iNOS expression between different groups by PCR and western blot. Detect the down-stream cytokines TNF-α,IL-1βand IL-6 by using ELISA. Results Histopathology showed that pulmonary fibrosis group mice had more severe fiber foci in alveolar septum, lesions, structural damage to the lung parenchyma.The in vitro experiment showed a inhibition effect of Tanshinone IIA on iNOS expression(P<0.05).TNF-α,IL-1βand IL-6 expressions decreased significantly compared to bleomycin group (P<0.05).Conclusion Tanshinone IIA can reduce pulmonary fibrosisin mice by regulating iNOS expression.

Key words: Tanshinone IIA, pulmonary fibrosis, iNOS