Objective To explore the mechanism by which diazepam alleviates lipopolysaccharide(LPS)-induced pyroptosis and inflammation to delay the progression of pulmonary fibrosis.Methods MRC-5 cells challenged with LPS were treated with diazepam and transfected with a let-7a-5p mimic alone or co-transfected with pc-DNA-MYD88.The changes in cellular expressions of inflammatory factors were analyzed with ELISA,and the expressions of fibrosis-and pyroptosis-related proteins were detected using Western blotting.In the animal experiment,C57BL/6 mice were randomized for treatment with LPS,LPS+diazepam,LPS+diazepam+let-7a-5p mimic,LPS+diazepam+ST2825(a MYD88 inhibitor),or LPS+diazepam+let-7a-5p mimic+pc-DNA-MYD88,and pulmonary fibrosis and pulmonary expression of α-SMA were examined using Masson staining and immunofluorescence staining,respectively.Results LPS exposure of MRC-5 cells significantly downregulated let-7a-5p expression,up-regulated MYD88 expression,increased the levels of IL-4,IL-6,TGF-β and TNF-α,and enhanced the expressions of fibrosis-related proteins(Col-I,Col-III,and α-SMA)and pyroptosis-related proteins(NLRP3,caspase-1,ASC,and GSDMD-N).Diazepam treatment of LPS-stimulated cells effectively inhibited the expressions of inflammation-related factors and the fibrosis-and pyroptosis-related proteins.In C57BL/6 mice,diazepam treatment obviously alleviated LPS-induced pulmonary fibrosis and reduced and pulmonary expression of α-SMA,and these effects were further enhanced by treatment with let-7a-5p mimic or ST2825,but the effect of let-7a-5p mimic was significantly attenuated by MYD88 over-expression.Conclusion Diazepam can negatively regulate MYD88 by upregulating the expression of let-7a-5p to inhibit LPS-induced pyroptosis and inflammatory response,thereby alleviating lung fibrosis in mice.

Objective To explore the mechanism by which diazepam alleviates lipopolysaccharide(LPS)-induced pyroptosis and inflammation to delay the progression of pulmonary fibrosis.Methods MRC-5 cells challenged with LPS were treated with diazepam and transfected with a let-7a-5p mimic alone or co-transfected with pc-DNA-MYD88.The changes in cellular expressions of inflammatory factors were analyzed with ELISA,and the expressions of fibrosis-and pyroptosis-related proteins were detected using Western blotting.In the animal experiment,C57BL/6 mice were randomized for treatment with LPS,LPS+diazepam,LPS+diazepam+let-7a-5p mimic,LPS+diazepam+ST2825(a MYD88 inhibitor),or LPS+diazepam+let-7a-5p mimic+pc-DNA-MYD88,and pulmonary fibrosis and pulmonary expression of α-SMA were examined using Masson staining and immunofluorescence staining,respectively.Results LPS exposure of MRC-5 cells significantly downregulated let-7a-5p expression,up-regulated MYD88 expression,increased the levels of IL-4,IL-6,TGF-β and TNF-α,and enhanced the expressions of fibrosis-related proteins(Col-I,Col-III,and α-SMA)and pyroptosis-related proteins(NLRP3,caspase-1,ASC,and GSDMD-N).Diazepam treatment of LPS-stimulated cells effectively inhibited the expressions of inflammation-related factors and the fibrosis-and pyroptosis-related proteins.In C57BL/6 mice,diazepam treatment obviously alleviated LPS-induced pulmonary fibrosis and reduced and pulmonary expression of α-SMA,and these effects were further enhanced by treatment with let-7a-5p mimic or ST2825,but the effect of let-7a-5p mimic was significantly attenuated by MYD88 over-expression.Conclusion Diazepam can negatively regulate MYD88 by upregulating the expression of let-7a-5p to inhibit LPS-induced pyroptosis and inflammatory response,thereby alleviating lung fibrosis in mice.