Effect of honokiol regulating SIRT3 on chronic hypoxia-induced microglia and astrocyte polarization
Objective:To investigate the effect of honokiol on microglia polarization and the underlying mechanism.Meth-ods:Inflammatory factors were detected using ELISA to determine the optimal concentration of cobalt chloride to induce,and that of honokiol to treat chronic hypoxia(48 h)in microglia cell line BV2 cells.BV2 cells were divided into four groups:control,chronic hypoxia,chronic hypoxia+honokiol,chronic hypoxia+honokiol+3-TYP(SIRT3 inhibitor).ELISA was used to mea-sure the concentration of supernatant TNFα and IL-1β proteins,qPCR was used to detect the expression of cellular M1 and M2 po-larization markers,and biochemical assays were used to detect the level of reactive oxygen species in each group.Western Blot was used to detect protein levels of SIRT3 and upstream inflammatory molecules NLRP3 and caspase1.Results:Chronic cobalt chloride stimulation of BV2 cells at an optimal concentration of 100 μmol/L significantly increased the release of inflammatory fac-tors TNFα and IL-1β after stimulation compared with the control group(P<0.05);compared with the control group,cells in the chronic hypoxia group had down-regulation of SIRT3 protein expression,whereas the ROS levels,NLRP3 and caspase1 protein levels,the M1 polarization marker CD86,iNOS mRNA levels and CD16/32 ratio were upregulated.and honokiol(10 μmol/L)significantly up-regulated the SIRT3 protein and mRNA levels of M2 markers Arg-1 and CD206 in chronic hypoxic cells(P<0.05)and down-regulated levels of ROS,NLRP3/caspase1 protein,and mRNA levels of M1 markers(P<0.05),and this anti-oxidative and anti-inflammatory effect was able to be reversed by SIRT3 inhibitor.Conclusion:Honokiol inhibits chronic hypoxia-induced microglia M1 polarization and inflammatory pathway activation,and its anti-inflammatory effects are SIRT3-de-pendent.