Characteristics And Their Implication Of CD39~+ And/or PD-1~+ T Cells In Patients With Chronic HIV-1 Infection

Background:CD39 is an extracellular nucleotidase that acts on the adenosine pathway.In the extracellular environment,CD39 hydrolyzes ATP to AMP.AMP continues to hydrolyze to produce adenosine under the action of another extracellular nucleotide enzyme,CD73.Studies have shown that the percentage of CD39⁺CD4 Treg in HIV-1infected patients is related to disease progression,and that expression of CD39 is up-regulated on virus-specific CD8 T cells.Furthermore,the percentage of CD39 and PD-1 co-expression is as high,while PD-1 is an exhaustive marker,so CD39 is also an exhaustive marker of CD8 T cells.At the same time,CD39⁺CD8 T has been proved to have immunomodulatory function,and CD39⁺CD8 T is a group of cells enriched with specific antigens in tumor immunity.However,the characteristics and mechanism of CD39⁺CD8 T cells in chronic HIV-1 infection have not been reported,and the expression and clinical significance of CD39⁺PD-1⁺CD4 T cells in HIV-1infection remains elusive.Objective:The aim of this study was to investigate the changes of CD39 and PD-1 in T cells of patients with chronic HIV-1 infection and their clinical significance.Methods:This study enrolled 71 HIV-1 infected patients,including 40 typical progressors（TNs）,21 complete responders（CRs）,and 10 immunological non-responders（INRs）,meanwhile,11 age-and sex-matched healthy individuals were included as health controls（HCs）.（1）The expression of CD39 and PD-1 on CD4 T,CD8 T cells in peripheral blood of HIV-1 infected patients was detected by flow cytometry,and analyzed its correlation with CD4 T cell counts and viral load.（2）We used real-time quantitative PCR to detect HIV reservoir in CRs and INRs patients,and analyzed their correlations with the frequencies of CD39⁺PD-1⁺CD4 cells.（3）We used flow cytometry to detect the expression of A_2AR in patients with chronic HIV-1infection and healthy controls,and compared the MFI value of A_2AR in CD39⁺,CD39^-,PD-1⁺and PD-1^-T cells in TNs and HCs.（4）The effect of exogenous adenosine on the function of CD8 T cells was observed in vitro.（5）The changes of CD8 T cell and HIV specific T cell function after intervention of adenosine targeted pathway and/or PD-1pathway were observed in vitro.（6）The expression of P24 in CD4 T cell population was detected in vitro,and the killing function of HIV-specific T cells to the HIV latent reservoir was observed.Results:（1）Compared with the HCs,the expression of CD39⁺,PD-1⁺and CD39⁺PD-1⁺on T cells in HIV-1 infected patients were significantly increased,especially in TNs.In CRs,the expressions of CD39 and PD-1 decreased,but were still higher than those in HCs.The frequency of CD39⁺PD-1⁺CD4 cells in INRs was significantly higher than CRs.（2）Correlation analysis showed that the frequency of CD39⁺CD8 T,PD-1⁺CD8 T,CD39⁺PD-1⁺CD8 T and CD39⁺PD-1⁺CD4 T cell was negatively correlated with CD4 cell count,and the frequency of CD39⁺CD8 T,CD39⁺PD-1⁺CD8 T,and CD39⁺PD-1⁺CD4 T cell were positively correlated with viral load.（3）The frequency of CD39⁺PD-1⁺CD4 cell subsets in patients with antiretroviral therapy（ART）for more than two years was positively correlated with HIV DNA and cell-associated HIV usRNA（4）The results of flow cytometry analysis showed that the expression of A_2AR in CD39⁺CD8 T,PD-1⁺CD8 T cells was higher than the negative cell population;（5）Compared with the control groups,CADO could reduce the secretion of cytokines by CD8 T cells in HIV-1 infected patients;（6）In vitro combined blocking of PD-1 and CD39/adenosine signaling showed synergic effect on restoring CD8 T cell function,and HIV-specific T cells could kill the HIV-1 latent reservoir;（7）These data indicate that the function of effector CD8 T cells expressing CD39 and PD-1molecules is increased,which is related to the progression of HIV/AIDS disease.At the same time,expansion of CD39⁺PD-1⁺CD4 cells is associated with failure of immune reconstitution in the HIV-1 patients who received long-term ART.The mechanism might be that CD39⁺PD-1⁺CD4 cells promote the establishment of latent reservoir of HIV.Conclusions:This study elucidated the characteristics and clinical significance of CD39 and PD-1 in T cells of patients with chronic HIV-1 infection.By targeting adenosine pathway and/or combining PD-1/PD-L1 pathway,we can observe the changes of the function of effector cells,which may open a new direction for the target therapy of the disease.