Liver immunity index: circulating HBV-specific CXCR6+ CD8 T-cells mirror intrahepatic anti-viral T cell immunity and predict immune control in models of chronic hepatitis B
WINTERSTELLER H. 1, BOSCH M. 1, DONAKONDA S. 1, KOSINSKA A. 2,3, ATES E. 2,3, WURMSER C. 4, ZEHN D. 4, PROTZER U. 2,3, WOHLLEBER D. 1, KNOLLE P. 1,3
1 Institute of Molecular Immunology, Technical University of Munich, Munich, Germany; 2 Institute of Virology, Technical University of Munich, Munich, Germany; 3 German Center for Infection Research, Munich, Germany; 4 Division of Animal Physiology and Immunology, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
Persistent hepatic viral infections, such as chronic hepatitis B, are characterized by a scarcity and dysfunction of virus-specific CD8 T cells in the liver and circulation. Immunotherapies, such as therapeutic vaccination, thus aim to reinvigorate and expand CD8 T cell immunity to control viral infections in the liver. To overcome the necessity of liver biopsies for immune monitoring of immunotherapies, this work suggests a novel diagnostic approach, by identifying markers on circulating virus-specific CD8 T cells which reflect the immune response in the liver.
Using pre-clinical models of adenoviral hepatocyte-specific delivery of nominal antigens and HBV genomes, we studied the dynamics of virus-specific T cell responses by flow cytometry and single-cell RNA sequencing (scRNAseq).
Following adenoviral transduction of hepatocytes, we detected local accumulation of CXCR6+ CD8 T cells with a liver-resident phenotype. During an acute-resolving infection, CXCR6+ CD8 T cells displayed potent effector functions, expressing high levels of Granzyme B and TNF/IFNγ after ex vivo stimulation, whereas CXCR6+ CD8 T cells in a persistent infection were rendered dysfunctional. Strikingly, the phenotype and functionality of CXCR6+ CD8 T cells circulating in peripheral blood were identical to their counterparts in the liver, and predicted infection outcome. Notably, CXCR6+ CD8 T cells developed solely upon recognition of their antigen in the liver and not upon systemic DNA vaccination in the absence of infection. scRNAseq analyses of virus-specific CD8 T cells confirmed a highly similar transcriptional profile of CD8 T cells from the liver and blood and revealed a Tcf7+ progenitor population, offering a target for therapeutic vaccination.
Our results report the occurrence of virus-specific CXCR6+ CD8 T cells in the circulation, that have previously seen their antigen in the liver, and provide the basis for using CXCR6 as a predictive marker for intrahepatic immune responses in treated chronic hepatitis B patients.