Th17 deviation under influence of Th1 response attenuates the inflammation in late phase of influenza virus infection (VIR5P.1138)

Abstract

Abstract Overwhelming inflammation with cytokine storm has been postulated as a major cause of severe influenza disease in human. In our influenza Ag- specific mouse experimental system, we discovered a Th17 deviation of CD4+ T cell response with resultant attenuation of inflammation in the late phase of influenza infection. Naïve hemagglutinin (HA)-specific CD4+ T cells respond to acute influenza virus infection with Th1 phenotype. In the presence of antigen specific Th1 CD4+ T cells, naïve CD4+ T cells adoptively transferred 4 days after the acute infection are activated with deviation to the Th17 phenotype. The second batch of naïve HA-specific CD4+ T cells is activated in an environment enriched with Th1 cytokines and active TGF-β. They proliferate, secrete IL-17 but not IFN-γ and express LAG-3 on the cell surface. They can suppress T cell activation in vitro and decrease lung inflammation in vivo. The 6.5 mice, with monotonous TCR repertoire responsive to influenza HA, reveal a Th17 deviated CD4+ T cell response and significant survival benefit in influenza virus infection. Consecutive waves of naïve CD4+ T cells from the thymus in 6.5 mice are probably activated as subsequent batches of naïve CD4+ T cells, with Th17 deviation which attenuates the inflammation in late phase of influenza virus infection.