The effects of emodin on lipopolysaccharide induced pyroptosis of human dental pulp fibroblasts by regula-ting HMGB1/TLR4 signaling pathway
Objective:To investigate the effects of emodin on lipopolysaccharide(LPS)induced pyroptosis of human dental pulp fibro-blasts(HDPFs)by regulating the high mobility group protein B1(HMGB1)/Toll-like receptor 4(TLR4)signaling pathway.Methods:HDPFs were in vitro cultured and grouped into control(normal culture),LPS with low,medium and high dose emodin groups,pcDNA(transfected with pcDNA3.1)and pcDNA-HMGB1 groups(transfected with pcDNA3.1 HMMGB1).qRT-PCR was applied to detect the expression level of HMGB1 mRNA in cells,MTT assay,plate cloning assay and flow cytometry were applied to detect cell prolifera-tion and pyrotosis,respectively.ELISA was applied to detect levels of IL-18,IL-1β and TNF-α in cell supernatant.Western blot was applied to detect the expression of pyroptosis protein Nod-like receptor protein 3(NLRP3),cleaved caspase-1,GSDMD,HMGB1 and TLR4 proteins in the cells.Results:Compared with the control group,the HMGB1 mRNA level,pyrotosis rate,IL-18,IL-1β,TNF-α levels,NLRP3,cleaved Caspase-1,GSDMD,HMGB1,TLR4 protein levels in the LPS group obviously increased,the A490 value and colony formation obviously decreased(P<0.05).Compared with the LPS group,the above indicators in the low,medium,and high dose emodin groups decreased,the A490 value and colony formation increased,the high-dose emodin group showed more obvious changes(P<0.05);overexpression of HMGB1 attenuated the inhibitory effects of emodin on LPS-induced pyroptosis and inflammation of HDPFs,and promoted cell proliferation(P<0.05).Conclusion:Emodin inhibit the activation of NLRP3 inflammasome by inhibiting the HMGB1/TLR4 pathway,thereby reduces LPS induced pyroptosis of HDPFs.