apyrase and HIV-Infections

Natural regulatory T cells (Tregs) participate in responses to various chronic infections including HIV. HIV infection is associated with a progressive CD4 lymphopenia and defective HIV-specific CD8 responses known to play a key role in the control of viral replication. Persistent immune activation is a hallmark of HIV infection and is involved in disease progression independent of viral load. The consequences of Treg expansion, observed in HIV infection, could be either beneficial, by suppressing generalized T-cell activation, or detrimental, by weakening HIV-specific responses and thus contributing to viral persistence. The resulting balance between Tregs contrasting outcomes might have critical implications in pathogenesis. Topics covered in this review include HIV-induced alterations of Tregs, Treg cell dynamics in blood and tissues, Treg-suppressive function, and the relationship between Tregs and immune activation. This review also provides a focus on the role of CD39(+) Tregs and other regulatory cell subsets. All these issues will be explored in different situations including acute and chronic infection, antiretroviral treatment-mediated viral control, and spontaneous viral control. Results must be interpreted with regard to both the Treg definition used in context and to the setting of the disease in an attempt to draw clearer conclusions from the apparently conflicting results.

Topics: Animals; Anti-HIV Agents; Antigens, CD; Apyrase; CD4-Positive T-Lymphocytes; Chlorocebus aethiops; Diphtheria Toxin; Disease Progression; Forkhead Transcription Factors; HIV Infections; HIV Seronegativity; HIV-1; Humans; Immune Reconstitution Inflammatory Syndrome; Immune Tolerance; Immunity, Cellular; Immunity, Mucosal; Interleukin-2; Lymphocyte Activation; Lymphocyte Count; Lymphoid Tissue; Recombinant Fusion Proteins; Recombinant Proteins; Simian Acquired Immunodeficiency Syndrome; T-Lymphocytes, Regulatory; Virus Replication

Human Ag-specific CD4(+) T cells can be detected by their dual expression of CD134 (OX40) and CD25 after a 44 hours stimulation with cognate Ag. We show that surface expression of CD39 on Ag-specific cells consistently identifies a substantial population of CD4(+) CD25(+) CD134(+) CD39(+) T cells that have a Treg-cell-like phenotype and mostly originate from bulk memory CD4(+) CD45RO(+) CD127(low) CD25(high) CD39(+) Treg cells. Viable, Ag-specific CD25(+) CD134(+) CD39(+) T cells could be expanded in vitro as cell lines and clones, and retained high Forkhead Box Protein 3, CTLA-4 and CD39 expression, suppressive activity and Ag specificity. We also utilised this combination of cell surface markers to measure HIV-Gag responses in HIV(+) patients before and after anti-retroviral therapy (ART). Interestingly, we found that the percentage of CD39(-) cells within baseline CD4(+) T-cell responses to HIV-Gag was negatively correlated with HIV viral load pre-ART and positively correlated with CD4(+) T-cell recovery over 96 weeks of ART. Collectively, our data show that Ag-specific CD4(+) CD25(+) CD134(+) CD39(+) T cells are highly enriched for Treg cells, form a large component of recall responses and maintain a Treg-cell-like phenotype upon in vitro expansion. Identification and isolation of these cells enables the role of Treg cells in memory responses to be further defined and provides a development pathway for novel therapeutics.

Topics: Antigens, CD; Antigens, Viral; Apyrase; CD4 Antigens; Female; Gene Expression Regulation; HIV Core Protein p24; HIV Infections; HIV-1; Humans; Interleukin-2 Receptor alpha Subunit; Male; Receptors, OX40; T-Lymphocytes, Regulatory; Viral Load

Regulatory T cells (Tregs) act by suppressing the activation and effector functions of innate and adaptive immune responses. HIV infection impacts Treg proportion and phenotype, although discrepant results have been reported depending on the patient population and the way Tregs were characterized. The effects of highly active antiretroviral therapy (HAART) on Treg frequency have not been thoroughly documented. We performed a detailed longitudinal analysis of Treg frequency and phenotype in 11 HIV-infected individuals enrolled in a single, prospective clinical trial, in which all patients underwent the same treatment protocol and were sampled at the same time points. Tregs were characterized for their expression of molecules associated with activation, cell cycle, apoptosis, or function, and compared to circulating Tregs from a group of age-matched healthy individuals.Our results revealed increased proportions, but reduced absolute numbers of circulating CD3(+)CD4(+)FOXP3(+) Tregs in chronically infected HIV-infected patients. Treg frequency was largely normalized by HAART. Importantly, we show that similar conclusions were drawn regardless of the combination of markers used to define Tregs. Our results also showed increased expression of cell cycle markers (Ki67 and cyclin B) in Tregs from untreated infected individuals, which were decreased by HAART. However, the Treg phenotype in untreated patients was not consistent with a higher level of generalized activation, as they expressed very low levels of CD69, slightly elevated levels of HLA-DR and similar levels of GARP compared to Tregs from uninfected donors. Moreover, none of these markers was significantly changed by HAART. Treg expression of CTLA-4 and cytotoxic molecules was identical between patients and controls. The most striking difference in terms of functional molecules was the high expression of CD39 by Tregs in untreated patients, which HAART only partially controlled.

Topics: Adult; Antigens, CD; Antiretroviral Therapy, Highly Active; Apyrase; Biomarkers; CD3 Complex; CD4-Positive T-Lymphocytes; Female; Gene Expression Regulation; HIV Infections; Humans; Immunophenotyping; Ki-67 Antigen; Longitudinal Studies; Male; Middle Aged; Phenotype; T-Lymphocytes, Regulatory; Viral Load

CCR5 antagonists block HIV cell entry through competitive binding to the CCR5 receptor present on the surface of CD4(+) cells. The CCR5 receptor is also present on CD8(+) cells involved in clearing hepatitis C virus (HCV). The goal of the present study was to examine the short-term safety of a CCR5 antagonist, vicriviroc, in patients with HIV/HCV coinfection.. A randomized, double-blind trial was conducted in 28 HIV/HCV-coinfected subjects with compensated liver disease and plasma HIV RNA below 400 copies/mL. All subjects were receiving a ritonavir-enhanced protease inhibitor regimen, to which vicriviroc (5, 10, or 15 mg/day) or placebo was added for 28 days. Clinical and laboratory evaluations were performed 21 days beyond the treatment period.. Treatment with vicriviroc resulted in no clinically meaningful changes in HCV or HIV viral load or any immune parameters. Adverse events were equally distributed among placebo and vicriviroc groups. Transaminase elevations of grade 1 or more were reported as AEs in 1 subject receiving 10-mg vicriviroc and 1 placebo subject. Vicriviroc plasma concentrations were similar to those observed in healthy subjects.. Short-term treatment with vicriviroc as part of a ritonavir-containing protease inhibitor-based regimen was safe and well tolerated in HIV/HCV-coinfected subjects. HIV/HCV coinfection also did not affect vicriviroc pharmacokinetics.

Topics: Adult; alpha-Fetoproteins; Antigens, CD; Antigens, CD19; Apyrase; C-Reactive Protein; CCR5 Receptor Antagonists; CD4 Antigens; CD4 Lymphocyte Count; CD8 Antigens; Double-Blind Method; Female; Hepacivirus; Hepatitis C; HIV Infections; HIV-1; Humans; Immunoglobulins; Liver; Lymphocyte Subsets; Male; Middle Aged; Piperazines; Pyrimidines; Viral Load

HIV infection promotes the expansion of immunosuppressive regulatory T-cells (Tregs), contributing to immune dysfunction, tissue fibrosis and disease progression. Early antiretroviral treatment (ART) upon HIV infection improves CD4 count and decreases immune activation. However, Treg dynamics and their epigenetic regulation following early ART initiation remain understudied.. Treg subsets were characterized by flow cytometry in 103 individuals, including untreated HIV-infected participants in acute and chronic phases, ART-treated in early infection, elite controllers (ECs), immunological controllers (ICs), and HIV-uninfected controls. The methylation status of six regulatory regions of the foxp3 gene was assessed using MiSeq technology.. Total Treg frequency increased overtime during HIV infection, which was normalized in early ART recipients. Tregs in untreated individuals expressed higher levels of activation and immunosuppressive markers (CD39, and LAP(TGF-β1)), which remained unchanged following early ART. Expression of gut migration markers (CCR9, Integrin-β7) by Tregs was elevated during untreated HIV infection, while they declined with the duration of ART but not upon early ART initiation. Notably, gut-homing Tregs expressing LAP(TGF-β1) and CD39 remained higher despite early treatment. Additionally, the increase in LAP(TGF-β1). Early ART initiation was unable to control the levels of immunosuppressive Treg subsets and their gut migration potential, which could ultimately contribute to gut tissue fibrosis and HIV disease progression.. This study was funded by the Canadian Institutes of Health Research (CIHR, grant MOP 142294) and in part by the AIDS and Infectious Diseases Network of the Réseau SIDA et maladies infectieuses du Fonds de recherche du Québec-Santé (FRQ-S).

Topics: Adult; Anti-HIV Agents; Antigens, CD; Apyrase; DNA Methylation; Epigenesis, Genetic; Female; Forkhead Transcription Factors; HIV Infections; Humans; Integrin beta Chains; Male; Receptors, CCR; T-Lymphocytes, Regulatory; Transforming Growth Factor beta

Topics: Antigens, CD; Apyrase; Biomarkers; CD4 Lymphocyte Count; Disease Progression; DNA, Viral; Gene Expression; HIV Infections; Host-Pathogen Interactions; Humans; Immunophenotyping; T-Lymphocytes, Regulatory; Viral Load

The expression pattern of the ectonucleotidases CD39 and CD73 on natural killer (NK) cells was examined in peripheral blood mononuclear cell of 61 HIV-1-infected patients. Increased frequencies of CD39CD56 NK cells were detectable in untreated HIV patients, which was associated with high viral load, low CD4 T-cell count, and CD8 T-cell activation. Additionally, levels of CD39 on NK cells were inducible by in vitro stimulation of NK cells, correlating with aryl hydrocarbon receptor and interleukin 10 expression. Here, we provide the first evidence of increased CD39CD56 NK cell frequencies during HIV infection, which might have consequences for NK cell function and HIV pathogenesis.

Topics: Antigens, CD; Apyrase; CD56 Antigen; Disease Progression; HIV Infections; HIV-1; Humans; Killer Cells, Natural; Lymphocyte Activation; Polymerase Chain Reaction; Viral Load

Recently, alterations of the T cell expression of the ectonucleotidases, CD39 and CD73, during HIV infection have been described. Here, peripheral (

Topics: 5'-Nucleotidase; Adult; Aged; Aged, 80 and over; Anti-HIV Agents; Antigens, CD; Apyrase; B-Lymphocytes; Case-Control Studies; CD4 Lymphocyte Count; Cell Differentiation; Cell Proliferation; Disease Progression; Female; Gene Expression Regulation; GPI-Linked Proteins; HIV Infections; Humans; Immunologic Memory; Ki-67 Antigen; Lymph Nodes; Lymphocyte Activation; Male; Middle Aged; Programmed Cell Death 1 Receptor; Receptors, Complement 3d; Tumor Necrosis Factor Receptor Superfamily, Member 7; Viremia

Correlates of death soon after antiretroviral therapy (ART) initiation remain unclear. We investigated the association between expression of CD39, a novel immune exhaustion marker, and early mortality in patients with human immunodeficiency virus/tuberculosis co-infection. Elevated pre-ART CD39+CD8+ T cell frequency was independently associated with mortality within 6 months of ART initiation.

Topics: Adult; Aged; Anti-Retroviral Agents; Antigens, CD; Antiretroviral Therapy, Highly Active; Apyrase; Biomarkers; Botswana; CD4 Lymphocyte Count; CD8-Positive T-Lymphocytes; Cohort Studies; Coinfection; Female; HIV Infections; Humans; Male; Middle Aged; Prospective Studies; Tuberculosis; Young Adult

Exhausted T cells express multiple co-inhibitory molecules that impair their function and limit immunity to chronic viral infection. Defining novel markers of exhaustion is important both for identifying and potentially reversing T cell exhaustion. Herein, we show that the ectonucleotidse CD39 is a marker of exhausted CD8+ T cells. CD8+ T cells specific for HCV or HIV express high levels of CD39, but those specific for EBV and CMV do not. CD39 expressed by CD8+ T cells in chronic infection is enzymatically active, co-expressed with PD-1, marks cells with a transcriptional signature of T cell exhaustion and correlates with viral load in HIV and HCV. In the mouse model of chronic Lymphocytic Choriomeningitis Virus infection, virus-specific CD8+ T cells contain a population of CD39high CD8+ T cells that is absent in functional memory cells elicited by acute infection. This CD39high CD8+ T cell population is enriched for cells with the phenotypic and functional profile of terminal exhaustion. These findings provide a new marker of T cell exhaustion, and implicate the purinergic pathway in the regulation of T cell exhaustion.

Topics: Animals; Antigens, CD; Apyrase; Arenaviridae Infections; Biomarkers; CD8-Positive T-Lymphocytes; Chromatography, High Pressure Liquid; Chronic Disease; Disease Models, Animal; Flow Cytometry; Hepatitis C, Chronic; HIV Infections; Humans; Lymphocytic Choriomeningitis; Lymphocytic choriomeningitis virus; Mice; Mice, Inbred C57BL; Oligonucleotide Array Sequence Analysis; RNA Virus Infections; T-Lymphocyte Subsets

The mechanisms by which Regulatory T cells suppress IL-2 production of effector CD4+ T cells in pathological conditions are unclear. A subpopulation of human Treg expresses the ectoenzyme CD39, which in association with CD73 converts ATP/ADP/AMP to adenosine. We show here that Treg/CD39+ suppress IL-2 expression of activated CD4+ T-cells more efficiently than Treg/CD39-. This inhibition is due to the demethylation of an essential CpG site of the il-2 gene promoter, which was reversed by an anti-CD39 mAb. By recapitulating the events downstream CD39/adenosine receptor (A2AR) axis, we show that A2AR agonist and soluble cAMP inhibit CpG site demethylation of the il-2 gene promoter. A high frequency of Treg/CD39+ is associated with a low clinical outcome in HIV infection. We show here that CD4+ T-cells from HIV-1 infected individuals express high levels of A2AR and intracellular cAMP. Following in vitro stimulation, these cells exhibit a lower degree of demethylation of il-2 gene promoter associated with a lower expression of IL-2, compared to healthy individuals. These results extend previous data on the role of Treg in HIV infection by filling the gap between expansion of Treg/CD39+ in HIV infection and the suppression of CD4+ T-cell function through inhibition of IL-2 production.

Topics: 5'-Nucleotidase; Adenosine; Antibodies, Monoclonal; Antigens, CD; Apyrase; Cell Proliferation; Cyclic AMP; DNA Methylation; HIV Infections; HIV-1; Humans; Interleukin-2; Lymphocyte Activation; Promoter Regions, Genetic; Receptor, Adenosine A2A; T-Lymphocyte Subsets; T-Lymphocytes, Regulatory

The role of the adenosine (ADO) suppression pathway, specifically CD39-expressing and CD73-expressing CD4⁺ T cells in HIV-1 infection is unclear.. We evaluated the frequency and numbers of CD4⁺CD39⁺ and CD4⁺CD73⁺ T cells, activated T cells, and plasma C reactive protein (CRP) levels in 36 HIV-1-positive individuals and 10 normal controls (NC). Low-level plasma viremia was evaluated using single copy assay. Mass spectrometry was used to measure hydrolysis of ATP by ectoenzyme-expressing CD4⁺ T cells, whereas cyclic adenosine monophosphate (cAMP) levels were measured using enzyme immunoassay. Suppression of T-cell function by exogenous ADO and CD4⁺CD73⁺ T cells was tested by flow cytometry.. CD39 and CD73 are expressed in different CD4⁺ T-cell subsets. CD4⁺CD73⁺ T cells do not express CD25 and FOXP3, and their frequency and numbers were lower in HIV-1-positive individuals regardless of virologic suppression (P=0.005 and P<0.001, respectively). CD4⁺CD73⁺ numbers inversely correlated with CD4⁺CD38⁺DR⁺ (P=0.002), CD8⁺CD38⁺DR⁺ T-cell frequency (P=0.05), and plasma CRP levels (P=0.01). Both subsets are required for hydrolysis of exogenous ATP to ADO and can increase CD4⁺ T-cell cAMP levels when incubated with exogenous ATP. Low-level viremia did not correlate with activated T-cell frequency. In vitro, ADO suppressed T-cell activation and cytokine expression. CD4⁺CD7⁺ T cells suppressed T-cell proliferation only in the presence of exogenous 5'-AMP.. The ADO-producing CD4⁺CD73⁺ subset of T cells is depleted in HIV-1-positive individuals regardless of viral suppression and may play a key role in controlling HIV-1-associated immune activation.

Topics: 5'-Nucleotidase; Adenosine; Adult; Aged; Antigens, CD; Apyrase; Biological Assay; C-Reactive Protein; Case-Control Studies; CD4-Positive T-Lymphocytes; Flow Cytometry; HIV Infections; HIV-1; Humans; Lymphocyte Activation; Mass Spectrometry; Middle Aged

There are conflicting data about the frequency and role of regulatory T cells (Tregs) during the course of HIV infection. Peripheral blood of a large cohort of HIV-infected patients (n = 131) at different stages of disease, including 15 long-term nonprogressors and 21 elite controllers, was analyzed to determine the frequency and phenotype of Tregs, defined as CD4(+), CD25(high), CD127(low), FoxP3(high) cells. A significantly increased relative frequency of Tregs within the CD4(+) compartment of HIV(+) patients compared to that of healthy controls (P < 0.0001) was observed. Additionally, the relative frequency of Tregs directly correlated with HIV viral load and inversely with CD4(+) counts. However, the absolute Treg number was reduced in HIV-infected patients versus healthy controls (P < 0.0001), with the exception of elite controllers (P > 0.05). The loss of absolute Treg numbers coincided with rising markers of immune activation (P < 0.0006). The initiation of antiviral therapy significantly increased absolute Treg numbers (P < 0.0031). We find that the expression of CD39, a newly defined ectonucleotidase with immunomodulatory functions on Tregs, correlated with progressive HIV disease, HIV viral load, and immune activation. Of note, when tested in peripheral blood mononuclear cells of healthy volunteers, the in vitro capacity to suppress T-cell proliferation was limited to CD4(+), CD25(high), CD39(+) T cells. Interestingly, Tregs of elite controllers exhibited not only the highest expression of CCR5, CTLA-4, and ICOS but also the lowest level of CD39. The data presented here reconcile the seemingly contradictory results of previous studies looking at Tregs in HIV and highlight the complexity of Treg-mediated immunoregulation during human viral infections.

Topics: Adult; Aged; Aged, 80 and over; Antigens, CD; Apyrase; Disease Progression; Female; Forkhead Transcription Factors; HIV Infections; Humans; Male; Middle Aged; T-Lymphocytes, Regulatory; Viral Load

We hypothesized that regulatory T cells (Tregs) could play a beneficial role during HIV infection by controlling HIV replication in conventional T cells (Tcons). Purified Tregs and Tcons from healthy donors were activated separately. Tcons were infected with the X4 or R5 HIV strains and cultured with or without autologous Tregs. Coculture of Tcons and Tregs resulted in a dose-dependent inhibition of Tcon infection, which was significant when a 1:1 Treg:Tcon ratio was used. Treg suppression of HIV infection was largely mediated by contact-dependent mechanisms. Blockage of cytotoxic T-lymphocyte-associated antigen-4 did not significantly reduce Treg function. In contrast, Tregs acted through cAMP-dependent mechanisms, because the decrease of cAMP levels in Tregs, the blockade of gap junction formation between Tregs and Tcons, the blockage of CD39 activity, and the blockage of protein kinase A in Tcons all abolished Treg-mediated suppression of HIV replication. Our data suggest a complex role for Tregs during HIV infection. Although Tregs inhibit specific immune responses, their inhibition of HIV replication in Tcons may play a beneficial role, particularly during early HIV infection, when the effector immune cells are not yet activated. Such a protective role of Tregs could have a profound impact on infection outcome.

Topics: Antigens, CD; Apyrase; Coculture Techniques; CTLA-4 Antigen; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Gap Junctions; HIV; HIV Infections; Humans; Lymphocyte Activation; Lymphocyte Cooperation; Lymphocyte Count; T-Lymphocytes; T-Lymphocytes, Regulatory; Virus Replication

HIV-1 infection is characterized by a chronic activation of the immune system and suppressed function of T lymphocytes. Regulatory CD4+ CD25(high) FoxP3+CD127(low) T cells (Treg) play a key role in both conditions. Here, we show that HIV-1 positive patients have a significant increase of Treg-associated expression of CD39/ENTPD1, an ectoenzyme which in concert with CD73 generates adenosine. We show in vitro that the CD39/adenosine axis is involved in Treg suppression in HIV infection. Treg inhibitory effects are relieved by CD39 down modulation and are reproduced by an adenosine-agonist in accordance with a higher expression of the adenosine A2A receptor on patients' T cells. Notably, the expansion of the Treg CD39+ correlates with the level of immune activation and lower CD4+ counts in HIV-1 infected patients. Finally, in a genetic association study performed in three different cohorts, we identified a CD39 gene polymorphism that was associated with down-modulated CD39 expression and a slower progression to AIDS.

Topics: Adenosine; Antigens, CD; Apyrase; Biomarkers; Bulgaria; Cell Proliferation; Cells, Cultured; Disease Progression; Down-Regulation; Forkhead Transcription Factors; France; Gene Expression; HIV Infections; Humans; Lymphocyte Activation; Polymorphism, Genetic; Receptor, Adenosine A2A; Survival Rate; T-Lymphocytes, Regulatory

Infection with the human immunodeficiency virus (HIV) results in alterations in immune cells such as an increase or decrease of cytokine secretion and immunodeficiency. HIV causes a state of chronic cellular activation that can induce apoptosis in lymphocyte T-helpers, making the patient susceptive to opportunistic infections. The biochemical mechanisms involved in this immune response to HIV have been researched. Here, we have shown for the first time that ATP and ADP hydrolysis are essential for the immune response to HIV. Our results clearly indicate an increase of NTPDase-1 (EC 3.6.1.5) activity in lymphocytes of HIV-positive patients, confirmed by an enhanced CD39 expression on its surface. These results suggest that NTPDase-1 may be important to keep an adequate balance between the generation and consumption of ATP and to preserve cellular integrity and immune response to the HIV infection.

Topics: Adult; Antigens, CD; Apyrase; Case-Control Studies; Female; HIV Infections; HIV-1; Humans; Lymphocytes; Male; Receptors, Interleukin-2

Human Immunodeficiency Virus type 1 (HIV-1) infects CD4+ T lymphocytes and various other cell types, including B cells. Since HIV-1 seropositive individuals have high numbers of B cells carrying Epstein-Barr Virus (EBV), and are at high risk for development of EBV-associated lymphoproliferative diseases, we studied the mode of HIV-1 infection in four EBV-positive lymphoblastoid B-cell lines (LCLs) as well as some molecular and biological features of the B cells infected by both viruses. We found that LCL cells were successfully infected in vitro by HIV-1, despite the lack of CD4 antigen expression on the cell membrane. LCL cells displayed a persistent, productive, and non-cytopathic infection. Moreover, HIV-1 infection induced reactivation of EBV latent genomes in one cell line. Following HIV-1 infection, LCL cells showed a decrease in B-cell activation markers CD23 and CD39, and an increase in CD10 immature B-cell antigen. Not all cells in each LCL expressed HIV-1 antigens, but all CD10+ cells also co-expressed the HIV-1 envelope protein gp 120. Furthermore, HIV-1 infected LCL cells grew as disperse suspensions, and formed more agar colonies than control, non-HIV-1-infected LCLs. These findings raise the possibility that HIV-1 might play a role in EBV reactivation, and in B-cell lymphoma pathogenesis in AIDS patients.

Topics: Adenosine Triphosphatases; Antigens, CD; Antigens, Differentiation, B-Lymphocyte; Apyrase; B-Lymphocytes; Cells, Cultured; DNA, Viral; Herpesvirus 4, Human; HIV Infections; HIV-1; Humans; Phenotype; Receptors, Fc; Receptors, IgE; Tumor Virus Infections; Virus Activation