CCL5-Secreting Virtual Memory CD8+ T Cells Inversely Associate With Viral Reservoir Size in HIV-1-Infected Individuals on Antiretroviral Therapy

Recent studies highlighted that CD8+ T cells are necessary for restraining reservoir in HIV-1-infected individuals who undergo antiretroviral therapy (ART), whereas the underlying cellular and molecular mechanisms remain largely unknown. Here, we enrolled 60 virologically suppressed HIV-1-infected individuals, to assess the correlations of the effector molecules and phenotypic subsets of CD8+ T cells with HIV-1 DNA and cell-associated unspliced RNA (CA usRNA). We found that the levels of HIV-1 DNA and usRNA correlated positively with the percentage of CCL4+CCL5- CD8+ central memory cells (T_CM) while negatively with CCL4-CCL5+ CD8+ terminally differentiated effector memory cells (T_EMRA). Moreover, a virtual memory CD8+ T cell (T_VM) subset was enriched in CCL4-CCL5+ T_EMRA cells and phenotypically distinctive from CCL4+ T_CM subset, supported by single-cell RNA-Seq data. Specifically, T_VM cells showed superior cytotoxicity potentially driven by T-bet and RUNX3, while CCL4+ T_CM subset displayed a suppressive phenotype dominated by JUNB and CREM. In viral inhibition assays, T_VM cells inhibited HIV-1 reactivation more effectively than non-T_VM CD8+ T cells, which was dependent on CCL5 secretion. Our study highlights CCL5-secreting T_VM cells subset as a potential determinant of HIV-1 reservoir size. This might be helpful to design CD8+ T cell-based therapeutic strategies for cure of the disease.