HBV persistence is enabled by dysfunctional antiviral immunity. CD8 T cells are key mediators of virus control but fail to clear the virus from chronically infected hosts. The role of hepatocytes during this process is less clear. We addressed the hypothesis that HBV infection alters antigen presentation by hepatocytes and mitigates cytotoxic T cell responses.
Primary human T cells were grafted with cloned T-cell receptor (TCR) recognizing either Glypican 3 (GPC3) as a typical liver cancer antigen, or myeloperoxidase (MPO), a neoantigen on leukemic cells. HepG2- or HuH7-cells grafted with the HBV receptor (NTCP) were used as target cells. T-cell mediated killing of hepatoma cells was monitored in real-time using the xCELLigence real-time cell analyzer. T cell activation was determined by cytokine release.
In a first set of experiments, HBV-permissive HepG2-NTCP cells were infected with HBV and co-cultured with T cells engrafted with a GPC3-specific TCR. As GPC3 is highly expressed on hepatoma cells, the GPC3-specific T cells killed all HepG2-NTCP cells. This was neither altered by HBV-infection nor in HBV-transgenic hepatoma cell lines HepG2-H1.3, HepG2-2.2.15 and HepG2-tgHBV-tRFP. Killing capacity correlated with IFN-γ-levels released as a marker for T-cell activation and remained unchanged irresepctive of HBV infection or replication. In a second set of experiments, the results were confirmed using HuH7-Lunet cells expressing MPO after mRNA-transfection. Again, HBV infection did not alter T-cell activation or T-cell mediated killing. In conclusion, HBV infection did not alter the hepatocyte microenviroment in our experiments in order to prevent T-cell activation or cytoxicity.
