Reversal of the CD8+ T-Cell Exhaustion Induced by Chronic HIV-1 Infection Through Combined Blockade of the Adenosine and PD-1 Pathways
Jing Li, Hui-Huang Huang, Bo Tu, Ming‐Ju Zhou, Wei Hu, Yulong Fu, Xiaoyu Li, Tao Yang, Jin‐Wen Song, Xing Fan, Yan‐Mei Jiao, Ruonan Xu, Ji‐Yuan Zhang, Chun‐Bao Zhou, Jin‐Hong Yuan, Cheng Zhen, Ming Shi, Fu‐Sheng Wang, Chao Zhang
Abstract
Background Targeting immune checkpoints for HIV treatment potentially provides a double benefit resulting from the ability to restore viral-specific CD8 + T-cell functions and enhance HIV production from reservoir cells. Despite promising pre-clinical data, PD-1 blockade alone in HIV-1-infected patients with advanced cancer has shown limited benefits in controlling HIV, suggesting the need for additional targets beyond PD-1. CD39 and PD-1 are highly co-expressed on CD8 + T cells in HIV-1 infection. However, the characteristics of CD39 and PD-1 dual-positive CD8 + T-cell subsets in chronic HIV-1 infection remain poorly understood. Methods This study enrolled 72 HIV-1-infected patients, including 40 treatment naïve and 32 ART patients. A total of 11 healthy individuals were included as controls. Different subsets of CD8 + T cells defined by CD39 and/or PD-1 expression were studied by flow cytometry. The relationships between the frequencies of the different subsets and parameters indicating HIV-1 disease progression were analyzed. Functional (i.e., cytokine secretion, viral inhibition) assays were performed to evaluate the impact of the blockade of adenosine and/or PD-1 signaling on CD8 + T cells. Results The proportions of PD-1 + , CD39 + , and PD-1 + CD39 + CD8 + T cells were significantly increased in treatment naïve patients but were partially lowered in patients on antiretroviral therapy. In treatment naïve patients, the proportions of PD-1 + CD39 + CD8 + T cells were negatively correlated with CD4 + T-cell counts and the CD4/CD8 ratio, and were positively correlated with viral load. CD39 + CD8 + T cells expressed high levels of the A2A adenosine receptor and were more sensitive to 2-chloroadenosine-mediated functional inhibition than their CD39 - counterparts. In vitro , a combination of blocking CD39/adenosine and PD-1 signaling showed a synergic effect in restoring CD8 + T-cell function, as evidenced by enhanced abilities to secrete functional cytokines and to kill autologous reservoir cells. Conclusion In patients with chronic HIV-1 infection there are increased frequencies of PD-1 + , CD39 + , and PD-1 + CD39 + CD8 + T cells. In treatment naïve patients, the frequencies of PD-1 + CD39 + CD8 + T cells are negatively correlated with CD4 + T-cell counts and the CD4/CD8 ratio and positively correlated with viral load. Combined blockade of CD39/adenosine and PD-1 signaling in vitro may exert a synergistic effect in restoring CD8 + T-cell function in HIV-1-infected patients.