Bone marrow stromal antigen 2 (BST-2) genetic variants influence expression levels and disease outcome in HIV-1 chronically infected patients

BACKGROUND: Bone marrow stromal antigen 2 (BST-2) also known as Tetherin (CD317/HM1.24), is a host restriction factor that blocks the release of HIV-1 virions from infected cells. Previous studies reported that BST-2 genetic variants or single nucleotide polymorphims (SNPs) have a preventative role during HIV-1 infection. However, the influence of BST-2 SNPs on expression levels remains unknown. In this study, we investigated the influence of BST-2 SNPs on expression levels and disease outcome in HIV-1 subtype C chronically infected antiretroviral therapy naïve individuals. RESULTS: We quantified BST-2 mRNA levels in peripheral blood mononuclear cells (PBMCs), determined BST-2 protein expression on the surface of CD4+ T cells using flow cytometry and genotyped two intronic single nucleotide polymorphisms (SNPs) rs919267 and rs919266 together with one SNP rs9576 located in the 3' untranslated region (UTR) of bst-2 gene using TaqMan assays from HIV-1 uninfected and infected participants. Subsequently, we determined the ability of plasma antibody levels to mediate antibody-dependent cellular phagocytosis (ADCP) using gp120 consensus C and p24 subtype B/C protein. Fc receptor-mediated NK cell degranulation was evaluated as a surrogate for ADCC activity using plasma from HIV-1 positive participants. BST-2 mRNA expression levels in PBMCs and protein levels on CD4+ T cells were lower in HIV-1 infected compared to uninfected participants (p = 0.075 and p < 0.001, respectively). rs919267CT (p = 0.042) and rs919267TT (p = 0.045) were associated with lower BST-2 mRNA expression levels compared to rs919267CC in HIV-1 uninfected participants. In HIV-1 infected participants, rs919267CT associated with lower CD4 counts, (p = 0.003), gp120-IgG1 (p = 0.040), gp120-IgG3 (p = 0.016) levels but higher viral loads (p = 0.001) while rs919267TT was associated with lower BST-2 mRNA levels (p = 0.046), CD4 counts (p = 0.001), gp120-IgG1 levels (p = 0.033) but higher plasma viral loads (p = 0.007). Conversely, rs9576CA was associated with higher BST-2 mRNA expression levels (p = 0.027), CD4 counts (p = 0.079), gp120-IgG1 (p = 0.009), gp120-IgG3 (p = 0.039) levels but with lower viral loads (p = 0.037). CONCLUSION: Our findings show that bst-2 SNPs mediate BST-2 expression and disease outcome, correlate with gp120-IgG1, gp120-IgG3 levels but not p24-IgG levels, ADCC and ADCP activity

Antigen Presenting Cells Contribute to Persistent Immune Activation Despite Antiretroviral Therapy Initiation During Hyperacute HIV-1 Infection

Human immunodeficiency virus (HIV)-induced changes in immune cells during the acute phase of infection can cause irreversible immunological damage and predict the rate of disease progression. Antiretroviral therapy (ART) remains the most effective strategy for successful immune restoration in immunocompromised people living with HIV and the earlier ART is initiated after infection, the better the long-term clinical outcomes. Here we explored the effect of ART on peripheral antigen presenting cell (APC) phenotype and function in women with HIV-1 subtype C infection who initiated ART in the hyperacute phase (before peak viremia) or during chronic infection. Peripheral blood mononuclear cells obtained longitudinally from study participants were used for immunophenotyping and functional analysis of monocytes and dendritic cells (DCs) using multiparametric flow cytometry and matched plasma was used for measurement of inflammatory markers IL-6 and soluble CD14 (sCD14) by enzyme-linked immunosorbent assay. HIV infection was associated with expansion of monocyte and plasmacytoid DC (pDC) frequencies and perturbation of monocyte subsets compared to uninfected persons despite antiretroviral treatment during hyperacute infection. Expression of activation marker CD69 on monocytes and pDCs in early treated HIV was similar to uninfected individuals. However, despite early ART, HIV infection was associated with elevation of plasma IL-6 and sCD14 levels which correlated with monocyte activation. Furthermore, HIV infection with or without early ART was associated with downmodulation of the co-stimulatory molecule CD86. Notably, early ART was associated with preserved toll-like receptor (TLR)-induced IFN-α responses of pDCs. Overall, this data provides evidence of the beneficial impact of ART initiated in hyperacute infection in preservation of APC functional cytokine production activity; but also highlights persistent inflammation facilitated by monocyte activation even after prolonged viral suppression and suggests the need for therapeutic interventions that target residual immune activation

Differing natural killer cell, T cell and antibody profiles in antiretroviral-naive HIV-1 viraemic controllers with and without protective HLA alleles

Previous work suggests that HIV controllers with protective human leukocyte antigen class I alleles (VC+) possess a high breadth of Gag-specific CD8+ T cell responses, while controllers without protective alleles (VC-) have a different unknown mechanism of control. We aimed to gain further insight into potential mechanisms of control in VC+ and VC-. We studied 15 VC+, 12 VC- and 4 healthy uninfected individuals (UI). CD8+ T cell responses were measured by ELISpot. Flow cytometry was performed to analyse surface markers for activation, maturation, and exhaustion on natural killer (NK) cell and T cells, as well as cytokine secretion from stimulated NK cells. We measured plasma neutralization activity against a panel of 18 Env-pseudotyped viruses using the TZM-bl neutralization assay. We found no significant differences in the magnitude and breadth of CD8+ T cell responses between VC+ and VC-. However, NK cells from VC- had higher levels of activation markers (HLA-DR and CD38) (p = 0.03), and lower cytokine expression (MIP-1β and TNF-α) (p = 0.05 and p = 0.04, respectively) than NK cells from VC+. T cells from VC- had higher levels of activation (CD38 and HLA-DR co-expression) (p = 0.05), as well as a trend towards higher expression of the terminal differentiation marker CD57 (p = 0.09) when compared to VC+. There was no difference in overall neutralization breadth between VC+ and VC- groups, although there was a trend for higher neutralization potency in the VC- group (p = 0.09). Altogether, these results suggest that VC- have a more activated NK cell profile with lower cytokine expression, and a more terminally differentiated and activated T cell profile than VC+. VC- also showed a trend of more potent neutralizing antibody responses that may enhance viral clearance. Further studies are required to understand how these NK, T cell and antibody profiles may contribute to differing mechanisms of control in VC+ and VC-

Early Initiation of Antiretroviral Therapy Preserves the Metabolic Function of CD4+ T Cells in Subtype C Human Immunodeficiency Virus 1 Infection

Background: Immune dysfunction often persists in people living with human immunodeficiency virus (HIV) who are on antiretroviral therapy (ART), clinically manifesting as HIV-1-associated comorbid conditions. Early ART initiation may reduce incidence of HIV-1–associated immune dysfunction and comorbid conditions. Immunometabolism is a critical determinant of functional immunity. We investigated the effect of HIV-1 infection and timing of ART initiation on CD4+ T cell metabolism and function. // Methods: Longitudinal blood samples from people living with HIV who initiated ART during hyperacute HIV-1 infection (HHI; before peak viremia) or chronic HIV-1 infection (CHI) were assessed for the metabolic and immune functions of CD4+ T cells. Metabolite uptake and mitochondrial mass were measured using fluorescent analogues and MitoTracker Green accumulation, respectively, and were correlated with CD4+ T cell effector functions. // Results: Initiation of ART during HHI prevented dysregulation of glucose uptake by CD4+ T cells, but glucose uptake was reduced before and after ART initiation in CHI. Glucose uptake positively correlated with interleukin-2 and tumor necrosis factor-α production by CD4+ T cells. CHI was associated with elevated mitochondrial mass in effector memory CD4+ T cells that persisted after ART and correlated with PD-1 expression. // Conclusions: ART initiation in HHI largely prevented metabolic impairment of CD4+ T cells. ART initiation in CHI was associated with persistently dysregulated immunometabolism of CD4+ T cells, which was associated with impaired cellular functions and exhaustion

Neutrophil Effector Functions Are Not Impaired in Duffy Antigen Receptor for Chemokines (DARC)-Null Black South Africans

Neutrophils are well-recognized for their pathogen killing mechanisms and disorders of neutrophil count and function are associated with recurrent infections. The Duffy Antigen Receptor for Chemokines (DARC)-null genotype is predominant in sub-Saharan African ancestry populations and is the major genetic determinant of benign ethnic neutropenia which has been associated with increased risk of Human Immunodeficiency Virus (HIV)-1 acquisition and mother-to-child transmission. However, the impact of DARC-null-linked neutropenia on HIV disease progression remains controversial. While the DARC-null genotype is associated with low numbers of circulating neutrophils, the effects of the polymorphism on neutrophil functions is unknown. We investigated the impact of the DARC-null trait and lower absolute neutrophil counts (ANCs) on key neutrophil effector functions [proteolytic activity within the phagosome following Fc receptor-mediated phagocytosis, reactive oxygen species (ROS) production, and neutrophil extracellular trap (NET) formation] in 20 HIV negative and 22 HIV-1 chronically infected black South Africans. Phagosome maturation was measured by flow cytometry following Fc-mediated uptake of IgG opsonized beads; ROS production was measured by chemi-luminescence after activation of neutrophils with phorbol 12-myristate 13-acetate (PMA). Activated neutrophils were also visualized by fluorescent microscopy for NET quantification. Study subjects were genotyped for the DARC trait using TaqMan allelic discrimination assays and ANCs were measured by full blood count. As expected, the DARC-null polymorphism was highly prevalent in our participant cohort (69%) and was strongly associated with lower ANCs in uninfected (p = 0.0007) and HIV-1 infected (p = 0.03) subjects. We observed enhanced proteolytic activity within the phagosome in the absence of DARC at 10 min (p = 0.05 and p = 0.009) and 60 min (p = 0.05 and p = 0.07) in uninfected and HIV-1 infected subjects, respectively. ROS was unaffected by DARC trait irrespective of HIV status. Furthermore, formation of NETs was reduced in neutrophils from DARC-null subjects (p = 0.04) following prolonged in vitro stimulation, but only in HIV-1 infected subjects. The data indicate differential neutrophil function in the absence of DARC that may be moderately modulated by HIV-1 infection but overall, the data suggest that DARC-null trait is not deleterious to neutrophil effector functions in African populations