Carnosine inhibits LPS-induced inflammasome activation and pyroptosis in microglia
Objective:To investigate the effects of carnosine on lipopolysaccharide(LPS)-induced inflammasome activation and pyroptosis in microglia,and to clarify its mechanism.Methods:Activation model of microglia was established by LPS(10 ng/ml).CCK-8 assay was used to detect cell activity of microglia treated with different concentrations of carnosine(0.2,1,5,20,50 mmol/L)for 6 h,and the cell activity of microglia pretreated with different concentrations of carnosine for 0.5 h and then stimulated with LPS for 6 h,to screen a suitable concentration.Then microglia were divided into control group,carnosine group(5 mmol/L),LPS group,and LPS+carnosine group:cell morphological changes in each group were observed under an inverted phase contrast microscope;levels of IL-1β,TNF-α and IL-6 in microglial culture medium were measured by ELISA;propidium iodide(PI)staining was used to detect py-roptotic cells;immunofluorescence was used to observe protein expression of Nod-like receptor protein 3(NLRP3).Results:Com-pared with control group,cell viability of microglia in LPS group was significantly decreased(P<0.01),the shape of microglia was mostly"amoeboid",levels of IL-1β,TNF-α and IL-6 in microglial culture medium were significantly increased(P<0.01),the posi-tive rate of PI and the number of NLRP3 positive cells were significantly increased(P<0.01).Compared with LPS group,cell viability of microglia in LPS+carnosine group was significantly increased(P<0.01),the number of"amoeboid"microglia was decreased,levels of IL-1β,TNF-α in microglial culture medium were significantly decreased(P<0.01),and the level of IL-6 was decreased(P<0.05),the positive rate of PI and the number of NLRP3 positive cells were both significantly decreased(P<0.01).Conclusion:Carnosine can inhibit LPS-induced microglia activation and inflammasome activation,thereby inhibiting cell pyroptosis and the release of inflammato-ry factors.
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