Foxp3(+)Helios(+) regulatory T cells are associated with monocyte subsets and their PD-1 expression during acute HIV-1 infection

BACKGROUND: Helios has been reported to stabilize regulatory T (Treg) suppressive function. Programmed cell death protein 1 (PD-1) expression in three human monocyte subsets modulates immune responses. Recently, our team reported that three monocyte subsets are associated with T helper cell differentiation in HIV-1-infected patients. Until now, the effects of monocyte subsets and their PD-1 expression on Foxp3(+)Helios(+) Treg cells have not been fully characterized, especially during acute HIV-1 infection. RESULTS: The frequency of Foxp3(+)Helios(+)CD45RA(+) Treg cells is significantly higher in patients with acute HIV-1 infection than those of healthy controls and chronic HIV-1-infected patients undergoing combined antiretroviral therapy. The frequency of Foxp3(+)Helios(+)CD45RA(+) Treg cells is inversely correlated with CD4 T-cell counts and the CD4/CD8 ratio in chronic HIV-1-infected patients. During acute HIV-1 infection, the frequency of Foxp3(+)Helios(+)CD45RA(+) Treg cells is inversely correlated with the frequency of the intermediate CD14(++)CD16(+) monocyte subset, but positively correlated with PD-1 expression in both intermediate CD14(++)CD16(+) and non-classical CD14(+)CD16(++) monocyte subsets. CONCLUSIONS: In this study, the perturbations of Foxp3(+)Helios(+) Treg cells were characterized, and the association between monocyte subsets and their PD-1 expression and Foxp3(+)Helios(+) Treg cells was evaluated during HIV-1 infection. Our observations provide new evidence of the roles for Foxp3(+)Helios(+) Treg cells and PD-1 expression on monocyte subsets in HIV pathogenesis.