Expansion of GARP-Expressing CD4^(+)CD25^(-)FoxP3^(+)T Cells and SATB1Association with Activation and Coagulation in Immune Compromised HIV-1-Infected Individuals in South Africa

Although antiretroviral treatment lowers the burden of human immunodeficiency virus(HIV)-related disease,it does not always result in immunological recovery.This manifests as persistent chronic inflammation,immune activation or exhaustion that can promote the onset of co-morbidities.As the exact function of regulatory T(Treg)cells in HIV remains unclear,this cross-sectional study investigated three expression markers(Forkhead box protein P3[FOXP3],glycoprotein A repetitions predominant[GARP],special AT-rich sequence binding protein 1[SATB1])and compared their expansion between CD4^(+)CD25^(-)and CD4^(+)CD25^(++)T cells.Age-matched study subjects were recruited(Western Cape,South Africa)and sub-divided:HIV-negative subjects(n=12),HIV-positive na(i|")ve treated(n=22),HIV-positive treated based on CD4 count cells/μL(CD4>500 and CD4<500)(n=34)and HIV-treated based on viral load(VL)copies/mL(VL<1000 and VL>1000)(n=34).Markers of immune activation(CD38)and coagulation(CD142)on T cells(CD8)were assessed by flow cytometry together with FOXP3,GARP and SATB1 expression on CD4^(+)CD25^(-)and CD4^(+)CD25^(++)T cells.Plasma levels of interleukin-10(IL-10;anti-inflammatory marker),IL-6(inflammatory marker)and D-dimer(coagulation marker)were assessed.This study revealed three major findings in immuno-compromised patients with virological failure(CD4<500;VL>1000):(1)the expansion of the unconventional Treg cell subset(CD4^(+)CD25^(-)FOXP3^(+))is linked with disease progression markers;(2)increased GARP expression in the CD4^(+)CD25^(-)and CD4^(+)CD25^(++)subsets;and(3)the identification of a strong link between CD4^(+)CD25^(-)SATB1+cells and markers of immune activation(CD8^(+)CD38^(+))and coagulation(CD8^(+)CD142^(+)and D-dimer).