IFN-γ facilitates liver fibrogenesis by CD161+CD4+ T cells through a regenerative IL-23/IL-17 axis in chronic hepatitis B virus infection.

Objectives This study aimed to determine the role of CD161+CD4+ T cells in chronic hepatitis B virus (HBV) infection. Methods A total of 94 patients with chronic hepatitis B (CHB), 73 with liver cirrhosis (LC) and 28 healthy controls were enrolled to determine frequency, cytokine production and chemokine receptor expression of circulating CD161+CD4+ T cells. Among these, 50 CHB and 34 LC patients were followed up for a period of 52-week entecavir monotherapy to assess the association of CD161+CD4+ T cells with seroconversion of HBV e antigen (HBeAg). In addition, 15 patients with hepatocellular carcinoma (HCC) and 15 with hepatic haemangioma (HHA) were enrolled to compare the paired circulating and intrahepatic CD161+CD4+ T cells. Results CD161+CD4+ T cells were found to accumulate in the circulation of HBV cohorts, which showed a significant correlation with the clinical parameters of disease progression. In addition, higher numbers of circulating CD161+CD4+ T cells were associated with an improved serological response of HBeAg to antiviral treatment. Moreover, CD161+CD4+ T cells as compared to homologous CD161-CD4+ T cells produced more pro-inflammatory cytokines including interleukin (IL)-17 and interferon (IFN)-γ and expressed higher levels of liver-homing chemokine receptors including CCR6, CXCR6 and CX3CR1. Notably, a significant enrichment of CD161+CD4+ T cell subsets co-expressing IFN-γ and IL-17 was observed in HBV-associated cirrhotic livers. During in vitro co-cultures, circulating CD161+CD4+ T cells in the chronic HBV setting exhibited prominent pro-fibrogenic effects by regulating primary hepatic stellate cells through a regenerative IFN-γ/IL-23/IL-17 axis. Conclusions In chronic HBV infection, CD161+CD4+ T cells play antiviral, pro-inflammatory and pro-fibrogenic roles.