低剂量二甲双胍延缓矽肺小鼠肺纤维化研究

Low dose metformin delays silicosis-induced pulmonary fibrosis in mice

目的探讨低剂量二甲双胍延缓矽肺小鼠肺纤维化的作用与机制。方法将无特定病原体级C57BL/6雄性小鼠随机分为4组,每组6只。采用一次性气管暴露法,矽肺模型组和二甲双胍干预组小鼠均予质量浓度为250 g/L的二氧化硅混悬液20μL,空白对照组和药物对照组小鼠均予0.9%氯化钠溶液20μL。染尘72.0 h后,药物对照组和二甲双胍干预组小鼠分别腹腔注射剂量为65 mg/kg体质量的二甲双胍,空白对照组和矽肺模型组小鼠均予等体积0.9%氯化钠溶液,隔天1次,连续28 d。干预结束后,观察小鼠肺组织病理学改变情况,计算肺脏器系数,以Ashcroft评分法评估肺组织纤维化程度,以实时荧光定量聚合酶链式反应法检测肺组织中纤维连接蛋白(Fn)1和Ⅰ型胶原蛋白(ColI)α1链(Col1a1)的mRNA相对表达水平,采用蛋白质印迹法测定肺组织中FN和COLⅠ的蛋白相对表达水平。结果肺组织病理学检查结果显示,空白对照组和药物对照组小鼠肺部无出现炎症和纤维化改变;矽肺模型组小鼠肺组织出现炎症和纤维化的改变;二甲双胍干预组小鼠肺组织炎症和纤维化程度均较矽肺模型组减轻。矽肺模型组小鼠肺组织肺脏器系数、Ashcroft评分,以及Fn1、Col1a1的mRNA和FN、COLⅠ蛋白的相对表达水平均高于空白对照组和药物对照组(P值均<0.05)。二甲双胍干预组小鼠上述指标均低于矽肺模型组(P值均<0.05)。结论低剂量二甲双胍可延缓矽肺小鼠肺组织纤维化的进展;其机制可能与二甲双胍改善二氧化硅诱导的细胞外基质过度沉积有关。

Objective To investigate the effect and mechanism of low dose metformin in delaying pulmonary fibrosis in silicosis mice.Methods The specific pathogen free C57BL/6 male mice were randomly divided into four groups,with six mice in each group.Mice in the silicosis model group and the metformin intervention group were given 20μL of a mass concentration of 250 g/L silica suspension,and mice in the blank control group and the drug control group were given 20μL of 0.9%sodium chloride solution,using tracheal exposure method.After 72.0 hours of dust exposure,the mice of drug control group and metformin intervention group were intraperitoneally injected with metformin at a dose of 65 mg/kg body mass,while the mice in the blank control group and the silicosis model group were given 0.9%sodium chloride solution at the same volume,once every other day for 28 days.After the treatment,histopathological change of the lungs was observed,lung organ coefficient was calculated,degree of pulmonary fibrosis was evaluated with Ashcroft score,and mRNA expression of fibronectin(Fn)1 and collagen typeⅠ(COLⅠ)alpha 1(Col1a1)in lung tissues were detected by real-time fluorescence quantitative polymerase chain reaction.The relative expression of FN and COLⅠin lung tissues was determined by Western blot.Results The results of histopathological examination of the lungs showed that there were no inflammation and fibrosis in the lungs of mice in the blank control group and the drug control group;mice in silicosis model group had inflammation and fibrosis in lung;the degree of lung inflammation and fibrosis was reduced in the mice of metformin intervention group compared with the silicosis model group.The lung organ coefficient,Ashcroft score,the relative expression of Fn1 and Col1a1 mRNA,the relative expression of FN and COLⅠprotein in lung tissues increased in silicosis model group(all P<0.05),compared with those in both blank control group and drug control group.The indexes above decreased of mice in the metformin intervention group than those in the silicosis model group(all P<0.05).Conclusion Low-dose metformin can delay the progression of pulmonary fibrosis in silicosis mice.The mechanism may be related to metformin′s improving excessive deposition of extracellular matrix induced by silica.