HBV Promotes M2 Macrophage Polarization By SIRT1/Notch Signaling

Hepatitis B virus(HBV)immune evasion is an important cause of HBV long-term carrying and leading to chronic disease.Blocking HBV immune evasion is an important means to stop the chronic carrying and chronicization of HBV.Although the mechanism of chronic HBV infection has made some progress in recent years,the cellular and molecular mechanisms of HBV immune evasion remain to be further studied.Liver macrophages are important natural immune defense cells that process and present antigens,regulate immune responses,and clear pathogens to antagonize infections.They can be polarized into different phenotypes under different tissue microenvironments and different pathological conditions: macrophages that secrete pro-inflammatory cytokines and play a pro-inflammatory function are called M1macrophages;macrophages that suppress the immune response and play a major role in tissue repair function are called M2 macrophages.The polarization of macrophages is widespread in the development of various diseases such as tumors,viral infections and cardiovascular diseases.Among them,M2 macrophage polarization plays a very important role in HBV immune evasion,but its underlying molecular mechanism is still unclear.In this study,we used an acute HBV infection model by injecting pHBV1.3plasmid into the tail vein.The liver tissue sections showed that HBV significantly promoted the expression of M2 marker molecule Arginase-1(Arg1)in hepatic macrophages.By analyzing the correlation between HBV expression level and M1/M2 phenotype marker molecules,the results showed that the M2 phenotype characteristic molecule Arg1 was positively correlated with HBV pregenomic RNA(HBV pgRNA),while the M1 phenotype characteristic molecule inducible nitric oxide synthase(iNOS)was negatively correlated with HBV pgRNA.This indicates that HBV promotes M2 macrophage polarization in mice.In vitro cell experiments,RAW264.7 cells,THP-1 cells,and mouse bone marrow-derived macrophages(BMDM)were used to treat these cells in HBV conditioned medium.The results showed that HBV can significantly induce macrophage polarized to M2 phenotype.To elucidate its underlying molecular mechanisms,this study analyzed possible signaling pathways involved in HBV-induced macrophage polarization.The results showed that after HBV was applied to the above three macrophages,the NAD-dependent protein deacetylase sirtuin-1(SIRT1)protein level was significantlyup-regulated,while the Notch1 signal was inhibited.However,Notch1 overexpression in macrophages significantly inhibited HBV-induced M2 polarization.This result demonstrates that the SIRT1/Notch1 signaling pathway is involved in HBV-induced M2 polarization.Furthermore,we found that HBV promotes macrophage Akt phosphorylation and inhibits NF-κB nuclear translocation through Notch1 signaling,thereby inducing macrophage polarized to M2 phenotype.Finally,by transfecting pHBsplasmid or si-HBs,and pHBeplasmid or pHBV1.3-G1896 A mutant plasmid in vitro,both HBsAg and HBeAg induced M2 polarization by SIRT1/Notch1 signaling.This study revealed that hepatitis B surface antigen(HBsAg)and hepatitis B e antigen(HBeAg)regulate Akt phosphorylation via SIRT1/Notch1 signaling and affect nuclear translocation of NF-κB,thereby mediating macrophage polarized to M2 phenotype.The elucidation of this mechanism provides new ideas and potential targets for blocking HBV immune evasion and designing HBV immunotherapy.