Therapeutic potential of co-signaling receptor modulation in hepatitis B [scRNA-Seq]

Reversing CD8+ T cell dysfunction is crucial in therapeutic approaches to eliminate chronic hepatitis B virus (HBV) infection. However, the specific molecular targets for achieving this goal are not fully understood. In this study, we conducted a comprehensive analysis of the co-signaling receptors induced during hepatocellular priming and examined the trajectory and long-term fate of dysfunctional HBV-specific CD8+ T cells. Our findings demonstrate that early during intrahepatic priming, HBV-specific CD8+ T cells selectively upregulate co-inhibitory receptors PD-1, CTLA-4, and LAG-3, as well as co-stimulatory receptors OX40, 4-1BB, and ICOS. While blocking the co-inhibitory receptors had no significant impact, activating 4-1BB and OX40, but not ICOS, transformed these cells into potent antiviral effectors. Prolonged antigenic stimulation of intrahepatically-primed dysfunctional T cells led to the development of a self-renewing, long-lived, heterogeneous population with a unique transcriptional profile that only partially overlaps with other forms of T cell hyporesponsiveness. This population consists of a dysfunctional progenitor or stem-like (TSL) population and two distinct dysfunctional tissue-resident memory (TRM) cell populations, which are hierarchically related. While 4-1BB expression is maintained across all populations, OX40 expression is limited to TSL cells. At later stages, only stimulation of 4-1BB, not OX40, conferred antiviral activity to HBV-specific CD8+ T cells. These findings highlight the therapeutic potential of co-signaling receptor modulation for chronic HBV infection and suggest that targeting all dysfunctional tissue-resident T cells, rather than solely the stem-like precursors, represents a promising strategy, distinguishing it from other conditions characterized by chronic antigenic stimulation. Single-cell RNA sequencing was performed on Cor93 T cells 28 days after adoptive transfer into HBV Tg mice. These hepatocellularly (HC)-primed dysfunctional cells were compared to control Cor93 T cells injected into wild-type (WT) mice transduced with a replication-defective recombinant lymphocytic choriomeningitis-based vector (rLCMV-core) that targets the same antigen, a non-secretable version of the HBV core protein, to Kupffer cells (KC) and dendritic cells that are not naturally infected by HBV.