Low dose metformin delays silicosis-induced pulmonary fibrosis in mice / 中国职业医学

ABSTRACT

{L-End}Objective To investigate the effect and mechanism of low dose metformin in delaying pulmonary fibrosis in silicosis mice. {L-End}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 20 μL of a mass concentration of 250 g/L silica suspension, and mice in the blank control group and the drug control group were given 20 μL 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 COLⅠ in lung tissues was determined by Western blot. {L-End}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). {L-End}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.