Objective: To explore the effect of metformin on murine model of bleomycin (BLM)-induced lung injury and fibrosis. Methods: A total of 30 mice were divided into 3 groups: control, BLM, and BLM with metformin, in accordance with the random number table and each group had 10 mice. To induce the pulmonary fibrosis model, a concentration of 2 mg/ml bleomycin was intratracheally administered in the BLM group and BLM with metformin group with a volume of 1.75 μl/g, while the control group accepted saline with the same volume. Metformin (200 mg/kg) was given to the mice orally once a day from the day before intratracheal instillation of bleomycin to day 14. The daily survival condition of mice was recorded during 14 days. At day 14, HE-staining was used to assess the severity of fibrosis according to the method proposed by Ashcroft. Total lung collagen content was determined by hydroxyproline assay and Masson's trichrome staining. To examine the expression of fibronectin we used the method of immunohistochemistry staining. The changes of Transforming Growth Factor beta 1 (TGF-β(1)) in plasm, bronchoalveolar lavage fluid (BALF) and lung were measured by ELISA. Results: The survival rates of control group, BLM group and BLM with metformin group at day 14 were 10/10, 4/10 and 7/10 respectively. According to the method proposed by Ashcroft the score of metformin treated mice was significantly lower than that of the bleomycin model mice[(3.82±0.58) vs (7.79±0.06), (P<0.05)]. The hydroxyproline level in lung tissue were markedly attenuated in metformin treated mice compared with bleomycin model mice [(0.40±0.05) vs (0.73±0.10) μg/mg, (P<0.05)]. The level of TGF-β(1) in plasma, BALF and lung tissue were also decreased in mice treated with metformin compared with bleomycin model mice [(2.32±0.68) vs (4.59±0.45) ng/ml, (0.81±0.09) vs (1.40±0.06) ng/ml, (17.12±0.83) vs (21.25±0.69) ng/mg, all P<0.05]. Conclusion: Metformin can reduce the severity of pulmonary fibrosis in mice induced by bleomycin.
目的： 探讨二甲双胍对博来霉素诱导的小鼠肺纤维化的作用。 方法： 将30只小鼠按随机数字表法分为正常对照组、博来霉素组、二甲双胍组3组各10只。博来霉素组和二甲双胍组以1.75 μl/g气管内注射浓度为2 mg/ml的博来霉素以制造肺纤维化模型，正常对照组气管内注射等量生理盐水。于造模前一天，二甲双胍组给予二甲双胍溶液(200 mg/kg)灌胃，1次/d，连续14 d。观察各组用药期间小鼠生存状态，于造模后第14天取材并对肺组织进行HE染色、Masson染色及纤维连接蛋白免疫组化染色，根据Ashcroft评分评价肺纤维化程度；通过碱水解法测定肺组织中羟脯氨酸的含量；采用酶联免疫吸附(ELISA)法测定血浆、支气管肺泡灌洗液(BALF)以及肺组织中转化生长因子β(1)(TGF－β(1))的水平。 结果： 正常对照组、博来霉素组、二甲双胍组小鼠第14天存活率分别为10/10、4/10、7/10；二甲双胍组肺组织Ashcroft评分显著低于博来霉素组[(3.82±0.58)比(7.79±0.06)分，P<0.05]；二甲双胍组肺组织羟脯氨酸含量显著低于博来霉素组[(0.40±0.05)比(0.73±0.10)μg/mg，P<0.05]；二甲双胍组血浆、BALF、肺组织中TGF－β(1)含量均显著低于博来霉素组[(2.32±0.68)比(4.59±0.45)ng/ml、(0.81±0.09)比(1.40±0.06)ng/ml、(17.12±0.83)比(21.25±0.69)ng/mg，均P<0.05]。 结论： 二甲双胍可减轻博来霉素诱导的小鼠肺纤维化程度。.
Keywords: Bleomycin; Metformin; Pulmonary fibrosis; Transforming growth factor beta 1.