Abstract:Objective To study the intervention of Montelukast plus Prednisone in a rat model of pulmonary fibrosis (PF) induced by Bleomycin. Methods Sixty Wister rats were randomly divided into 5 groups including blank control, model control, Montelukast, Prednisone and combined Montelukast and Prednisone treatment groups. Pulmonary fibrosis model was induced by Bleomycin. The rats were sacrificed on the 7th and 28th day after modeling respectively. The degrees of lung inflammation and pulmonary fibrosis were detected by hematoxylin and eosin staining and Masson staining. The serum levels of connective tissue growth factor (CTGF) and TGF-β1 were assessed by enzyme-linked immunosorbent assay. The expressions of CTGF and TGF-β1 in lung tissues were evaluated by immunohistochemical staining. Results The scores of alveolitis in the model control group and the Montelukast group on day 7 were (1.63 ± 0.16) and (2.73 ± 0.15) respectively, the difference was significant between the two groups (P < 0.01). The scores of pulmonary fibrosis in the model control group and the Montelukast group on day 28 were (1.66 ± 0.10) and (2.76 ± 0.13) respectively, the difference was significant between the two groups (P < 0.01). On day 7, the TGF-β1 level in the lung tissues of the blank control, Montelukast, Prednisone and combined Montelukast and Prednisone treatment groups decreased as compared to the model control group with significant differences (P < 0.05). Compared with the model control group, the CTGF and TGF-β1 levels in the lung tissues of other groups significantly decreased on day 28 (P < 0.01). On day 7 and 28, the serum levels of CTGF and TGF-β1 in the model control group were significantly higher than those of other groups (P < 0.01). Conclusions The combined treatment of Montelukast and Prednisone can alleviate alveolitis and pulmonary fibrosis induced by Bleomycin, and its mechanism is associated with the reduced CTGF and TGF-β1 expressions in lung tissues.