No abstract

Accumulation of activated immune cells results in nonspecific hepatocyte killing in chronic hepatitis B (CHB), leading to fibrosis and cirrhosis. This study aims to understand the underlying mechanisms in humans and to define whether these are driven by widespread activation or a subpopulation of immune cells. We enrolled CHB patients with active liver damage to receive antiviral therapy and performed longitudinal liver sampling using fine-needle aspiration to investigate mechanisms of CHB pathogenesis in the human liver. Single-cell sequencing of total liver cells revealed a distinct liver-resident, polyclonal CD8 + T cell population that was enriched at baseline and displayed a highly activated immune signature during liver damage. Cytokine combinations, identified by in silico prediction of ligand-receptor interaction, induced the activated phenotype in healthy liver CD8 + T cells, resulting in nonspecific Fas ligand–mediated killing of target cells. These results define a CD8 + T cell population in the human liver that can drive pathogenesis and a key pathway involved in their function in CHB patients.

Background and Aims CD8 T cells are essential in controlling HBV infection. Viral control is dependent on efficient recognition of HBV‐infected hepatocytes by CD8 T cells, which can induce direct lysis of infected hepatocytes. In addition, CD8 T cells produce interferon (IFN)‐γ, which mediates noncytopathic viral clearance. Innate immunomodulators and HBV‐targeted RNA interference (RNAi) are being developed to treat chronic hepatitis B (CHB), but may modify HBV antigen presentation and impact CD8 T‐cell recognition, in addition to their primary mechanisms of action. Approach and Results HBV‐infected HepG2‐NTCP cells were treated with tenofovir disoproxil fumarate (TDF), Toll‐like receptor (TLR) 7/8 agonists, TLR7/8 conditioned media (CM) collected from immune cells, or RNAi using short interfering RNAs. The effect of these treatments on antigen presentation was measured through coculture with CD8 T cells recognizing human leukocyte antigen–A0201 restricted epitopes, HBc18‐27 or HBs183‐191. Cytokine profiles of TLR7/8 CM were measured using a cytometric bead array. TDF reduced viral replication, but not CD8 T‐cell recognition, of infected cells. Direct exposure of infected HepG2‐NTCP to TLR7/8 agonists had no impact on T‐cell recognition. Exposure of infected HepG2‐NTCP to TLR7/8 CM enhanced HBV‐specific CD8 T‐cell recognition through type 1 interferon (IFN) and IFN‐γ‐dependent mechanisms. RNAi rapidly suppressed HBV‐DNA, HBcAg, and HBsAg expression, impairing recognition by HBV‐specific CD8 T cells. Conclusions Immunomodulation and RNAi, but not nucleos(t)ide analogues, alter the recognition of infected HepG2‐NTCP by HBV‐specific CD8 T cells. Understanding these changes will inform combination treatments for CHB.