Interleukin-33 Reinvigorates Antiviral Function of Viral-Specific CD8+ T Cells in Chronic Hepatitis B Virus Infection

Restoration of exhausted hepatitis B virus (HBV)-specific CD8+ T cells is one of the important strategies for inhibition of viral replication. The role of interleukin (IL)-33 to recovery of CD8+ T cell activity is not fully elucidated. We investigated the effect of IL-33 on viral-specific CD8+ T cell responses in chronic hepatitis B (CHB) patients in vitro by both phenotypic and functional analysis. Plasma IL-33 was downregulated in CHB patients, while effective antiviral therapy rescued IL-33 expression. There was no significant difference of IL-33 receptor mRNA relative level in CD8+ T cells between CHB patients and controls. IL-33 induced the proliferation of HBV-specific CD8+ T cells, and reduced programmed death-1 expression on HBV-specific CD8+ T cells. IL-33 promoted the direct cytolytic activity of CD8+ T cells against HepG2.2.15 cells through boosting perforin and granzyme B production. Furthermore, IL-33 administration increased HBV-specific CD8+ T cell-mediated HBV replication and HBV antigen secretion mainly via enhancement of interferon-γ and tumor necrosis factor-α. IL-33 reinvigorated antiviral activity of HBV-specific CD8+ T cells, revealing that IL-33 might contribute to viral clearance in persistent HBV infection.