Quercetin suppresses pyroptosis in mouse fibroblasts by inhibiting the NLRP3/caspase-1/GSDMD pathway
Objective To investigate whether quercetin inhibits pyroptosis of mouse fibroblast NIH-3T3 cells by regulating the NLRP3/caspase-1/GSDMD signaling pathway.Methods NIH-3T3 cells were treated with quercetin or MCC950(a specific inhibitor of NLRP3)before stimulation with lipopolysaccharide(LPS)and ATP to induce cell pyroptosis.The optimal quercetin concentration and duration were screened using the CCK-8assay after testing various concentrations and times.Morphological changes of the treated cells was observed,and the levels of IL-18 and IL-1β in the cell culture supernatant were detected with ELISA;the protein expressions of NLRP3,cleaved caspase-1,and GSDMD-N and the mRNA levels of NLRP3,caspase-1 and GSDMD were detected using Western blotting and qRT-PCR.The changes in cell pyroptosis were examined with TUNEL staining and LDH release assay.Results The CCK-8 assay indicated that 24-hour treatment with 20 μmol/L quercetin yielded the most favorable results.LPS and ATP stimulation of NIH-3T3 cells induced obvious swelling,cell membrane rupture and leakage of cell contents,significantly increased IL-18 and IL-1β levels,and enhanced protein expressions of NLRP3,cleaved caspase-1 and GSDMD-N and mRNA levels of NLRP3,caspase-1 and GSDMD.LPS and ATP stimulation also caused a significant increment of TUNEL-positive cell counts and LDH release in NIH-3T3 cells.Treatment with quercetin or MCC950 significantly reduced cell pyroptosis induced by LPS and ATP,lowered the concentrations of IL-18 and IL-1β,decreased the expression levels of NLRP3,caspase-1/cleaved caspase-1,GSDMD/GSDMD-N,and reduced the number of TUNEL-positive cells and LDH release.Conclusion Quercetin suppresses pyroptosis of mouse fibroblasts stimulated with LPS and ATP and reduces secretion of inflammatory cytokines by inhibiting the NLRP3/caspase-1/GSDMD pathway.
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