Preferential loss of gut-homing α4β7 CD4+ T cells and their circulating functional subsets in acute HIV-1 infection

Preferential infection and depletion of gut-homing α4β7 CD4+ T cells in the blood are observed in chronic HIV/SIV infection. The dynamic change in gut-homing α4β7 CD4+ T cells and their functional subsets during the acute stages of HIV-1 infection are less documented. Therefore, we conducted a cohort study to investigate whether acute HIV-1 infection induced abnormalities in gut-homing α4β7 CD4+ T cells and their functional subsets. We examined the frequency, absolute number, and functionality of gut-homing α4β7 CD4+ T cells in 26 acute HIV-1-infected patients compared with 20 healthy individuals. We found that circulating gut-homing α4β7 CD4+ T cells were preferentially depleted during acute HIV-1 infection and were positively correlated with absolute CD4+ T-cell count in blood. Notably, Th17 and Th1 cell subsets of gut-homing CD4+ T cells were also decreased, which resulted in an imbalance of T helper cells (Th1):regulatory T cells (Treg) and Treg:Th17 ratios. Gut-homing Th17 and Th1 cells were also positively correlated with the absolute number of total CD4+ T cells and gut-homing CD4+ T cells. The gut-homing Treg:Th17 ratio was inversely correlated with the CD4+ T-cell count. Taken together, the analyses of our acute HIV-1 cohort demonstrate that gut-homing α4β7 CD4+ T cells and their functional subsets were profoundly depleted during acute HIV-1 infection, which may have resulted in the persistent loss of circulating CD4+ T cells and an imbalance of Th1:Treg and Treg:Th17 ratios and contribute to HIV-1 disease pathogenesis.