Intrahepatic exhausted antiviral immunity in an immunocompetent mouse model of chronic hepatitis B.

Background & aims: Targeting exhausted immune systems would be a promising therapeutic strategy to achieve a functional cure for HBV infection in chronic hepatitis B (CHB) patients. However, animal models recapitulating the immunokinetics of CHB are very limited. We aimed to develop an immunocompetent mouse model of CHB for intrahepatic immune profiling.

Methods: CHB mice were created by intrahepatic delivery of the Sleeping Beauty transposon vector tandemly expressing the hepatitis B virus (HBV) genome and fumarylacetoacetate hydrolase (FAH) cDNA into C57BL/6J congenic FAH knockout mice via hydrodynamic tail vein injection. We profiled the viral and intrahepatic immune kinetics in CHB mice with or without treatment with recombinant IFNα or the hepatotropic Toll-like receptor 7 agonist SA-5 using single-cell RNA-seq.

Results: CHB mice exhibited sustained HBV viremia and persistent hepatitis. They showed intrahepatic expansion of exhausted CD8+ T (Tex) cells, the frequency of which was positively associated with viral load. Recruited macrophages increased in number but impaired inflammatory responses in the liver. The cytotoxicity of mature NK cells also increased in CHB mice. IFNα and SA-5 treatment both resulted in viral suppression with mild hepatic flares in CHB mice. While both treatments activated NK cells, SA-5 had the capacity to revitalize the impaired function of Tex cells and liver-recruited macrophages.

Conclusion: Our novel CHB mouse model recapitulated the intrahepatic exhausted antiviral immunity in CHB patients, which might be able to be reinvigorated by a hepatotropic TLR7 agonist.