Plasmacytoid dendritic cells induce efficient stimulation of antiviral immunity in the context of chronic hepatitis B virus infection

The immune control of hepatitis B virus (HBV) infection is essential for viral clearance. Therefore, restoring functional antiHBV immunity is a promising immunotherapeutic approach to treatment of chronic infection. Plasmacytoid dendritic cells (pDCs) play a crucial role in triggering antiviral immunity through their ability to capture and process viral antigens and subsequently induce adaptive immune responses. We investigated the potential of pDCs to trigger antiviral cellular immunity against HBV. We used a human leukocyte antigen A (HLAA)*0201(+) pDC line loaded with HLAA*0201-restricted peptides derived from hepatitis B core/hepatitis B surface (HBc/HBs) antigens to amplify specific CD8 T cells ex vivo from chronic HBV patients and established a Hepato-HuPBL mouse model to address the therapeutic potential of the strategy in vivo. Stimulation of PBMCs or liver-infiltrating lymphocytes from HLAA*0201(+) chronic HBV patients by HBc peptide-loaded pDCs elicited up to 23.1% and 76.1% HBV-specific CD8 T cells in 45.8% of cases. The specific T cells from the responder group secreted interferon-gamma, expressed CD107 upon restimulation, and efficiently lysed HBV antigen-expressing hepatocytes. Circulating hepatitis B e antigen (HBeAg) was found to distinguish the group of patients not responding to the pDC stimulation. The therapeutic efficacy of the pDC vaccine was evaluated in immunodeficient NOD-SCID beta(2)m(-/-) mice reconstituted with HBV patients' PBMCs and xenotransplanted with human HBV-transfected hepatocytes. Vaccination of HepatoHuPBL mice with the HBc/HBs peptideloaded pDCs elicited HBV-specific T cells able to specifically lyse the transfected hepatocytes and reduce the systemic viral load. Conclusion: pDCs loaded with HBVderived peptides can elicit functional virus-specific T cells. HBeAg appears to be critical in determining the outcome of immunotherapies in chronic HBV patients. A pDC-based immunotherapeutic approach could be of interest in attempts to restore functional antiviral immunity, which is critical for the control of the virus in chronic HBV patients. (HEPATOLOGY 2012;56:17061718)