CXCL13-mediated recruitment of intrahepatic CXCR5+CD8+ T cells favors viral control in chronic HBV infection
Authors: Yongyin Li, Libo Tang, Ling Guo, Chengcong Chen, Shuqin Gu, Yang Zhou, Guofu Ye, Xiaoyi Li, Weibin Wang, Xinxin Liao, Yu Wang, Xiaohong Peng, Guangze Liu, Xiaoyong Zhang, Jian Sun, Jie Peng, Jinlin Hou
Journal: Journal of Hepatology (2019)

•CXCR5+CD8+T cells produce higher levels of HBV-specific IFN-γ and IL-21 than CXCR5−CD8+T cells.•CXCR5+CD8+T cells retain functional capacity in inhibiting HBV replication and supporting B cell antibody production.•PD1 blockade and exogenous IL-21 enhance production of IFN-γ from CXCR5+CD8+T cells.•High expression of intrahepatic CXCL13 facilitates CXCR5+CD8+T cell recruitment and promotes immune control of HBV. Background & AimsAlthough CD8+T cell exhaustion hampers viral control during chronic HBV infection, the pool of CD8+T cells is phenotypically and functionally heterogeneous. Therefore, a specific subpopulation of CD8+T cells should be further investigated. This study aims to dissect a subset of CD8+T cells expressing C-X-C motif chemokine receptor 5 (CXCR5) in chronic HBV infection.MethodsThe frequency of CXCR5+CD8+T cells and the levels of C-X-C motif chemokine ligand 13 (CXCL13), a chemokine of CXCR5, were measured in patients with chronic HBV infection. C57BL/6, interleukin (IL)-21 receptor- or B cell-deficient mice were hydrodynamically injected with pAAV-HBV1.2 plasmids. Phenotype and functions of peripheral and intrahepatic CXCR5+ and CXCR5−CD8+T cells were assessed.ResultsCXCR5+CD8+T cells were partially exhausted but possessed a stronger antiviral ability than the CXCR5− subset in patients with chronic HBV infection; moreover, CXCR5+CD8+T cells were associated with a favorable treatment response in patients with chronic hepatitis B (CHB). High levels of CXCL13 from patients with CHB facilitated the recruitment of intrahepatic CXCR5+CD8+T cells, and this subpopulation produced high levels of HBV-specific interferon (IFN)-γ and IL-21. Notably, PD1 (programmed death 1) blockade and exogenous IL-21 enhanced the production of IFN-γ. More strikingly, mice injected with CXCR5+CD8+T cells showed remarkably decreased expression of HBsAg. Additionally, an impaired production of HBV-specific IFN-γ from intrahepatic CXCR5+CD8+T cells was observed in IL-21 receptor- or B cell-deficient mice.ConclusionCXCL13 promotes the recruitment of CXCR5+CD8+T cells to the liver, and this subpopulation improves viral control in chronic HBV infection. The identification of this unique subpopulation may contribute to a better understanding of CD8+T cell functions and provide a potential immunotherapeutic target in chronic HBV infection.Lay summaryExhaustion of CD8+ T cells is an important factor in the development of chronic hepatitis B virus (HBV) infection. CD8+ T cells expressing the receptor CXCR5 are partially exhausted, but have potent antiviral activity, as they produce high levels of HBV-specific cytokines in chronic HBV infection. Increased expression of CXCL13 within the liver facilitates the recruitment of CXCR5+CD8+T cells and establishes effective immune control of HBV infection. Although CD8+T cell exhaustion hampers viral control during chronic HBV infection, the pool of CD8+T cells is phenotypically and functionally heterogeneous. Therefore, a specific subpopulation of CD8+T cells should be further investigated. This study aims to dissect a subset of CD8+T cells expressing C-X-C motif chemokine receptor 5 (CXCR5) in chronic HBV infection. The frequency of CXCR5+CD8+T cells and the levels of C-X-C motif chemokine ligand 13 (CXCL13), a chemokine of CXCR5, were measured in patients with chronic HBV infection. C57BL/6, interleukin (IL)-21 receptor- or B cell-deficient mice were hydrodynamically injected with pAAV-HBV1.2 plasmids. Phenotype and functions of peripheral and intrahepatic CXCR5+ and CXCR5−CD8+T cells were assessed. CXCR5+CD8+T cells were partially exhausted but possessed a stronger antiviral ability than the CXCR5− subset in patients with chronic HBV infection; moreover, CXCR5+CD8+T cells were associated with a favorable treatment response in patients with chronic hepatitis B (CHB). High levels of CXCL13 from patients with CHB facilitated the recruitment of intrahepatic CXCR5+CD8+T cells, and this subpopulation produced high levels of HBV-specific interferon (IFN)-γ and IL-21. Notably, PD1 (programmed death 1) blockade and exogenous IL-21 enhanced the production of IFN-γ. More strikingly, mice injected with CXCR5+CD8+T cells showed remarkably decreased expression of HBsAg. Additionally, an impaired production of HBV-specific IFN-γ from intrahepatic CXCR5+CD8+T cells was observed in IL-21 receptor- or B cell-deficient mice. CXCL13 promotes the recruitment of CXCR5+CD8+T cells to the liver, and this subpopulation improves viral control in chronic HBV infection. The identification of this unique subpopulation may contribute to a better understanding of CD8+T cell functions and provide a potential immunotherapeutic target in chronic HBV infection.