Aviremic Patients Research Articles

Antiretroviral therapy for adults infected with HIV: Guidelines for health care professionals from the Quebec HIV care committee

The appropriate use of antiretrovirals reduces morbidity and mortality caused by HIV infection. The present article provides health care professionals with a practical guide for the use of antiretrovirals. Therapy should be initiated based predominantly on clinical presentation and CD4 count, and should consist of three active drugs or at least two active drugs when this is not possible, as in cases of some treatment-experienced patients. This is the most effective way to achieve long-term suppression of viral replication. Selection of individual drugs in the regimen should consider the weight of the evidence supporting these choices, as well as their tolerability profiles and ease of use, the patients' comorbidities and treatment history. Treatment interruption is not recommended, either in aviremic patients or in those who have experienced virological failure. Instead, the therapeutic regimen should be adjusted to minimize side effects, promote adherence and suppress viral replication.

Cognitive dysfunction in HIV patients despite long-standing suppression of viremia

To determine the prevalence of cognitive complaints and HIV-associated neurocognitive disorders (HANDs) in a cohort of aviremic HIV-positive patients. To evaluate the relevance of the HIV dementia scale to detect HANDs. Assessment of HANDs with neuropsychological tests. Two hundred HIV-infected patients with undetectable HIV-1 RNA concentrations in the plasma, no history of major opportunistic infection of the central nervous system in the past 3 years, no current use of intravenous drugs, and no major depression answered a questionnaire designed to elicit cognitive complaints. Cognitive functions of 50 complaining and 50 noncomplaining HIV-positive patients were assessed. Patients had undetectable HIV-1 RNA concentrations for a median time of 48 months (range 3.2-136.6). The prevalence of cognitive complaints was 27%. The prevalence of HANDs was 84% among patients with cognitive complaints (asymptomatic neurocognitive impairment 24%, mild neurocognitive disorders 52%, and HIV-associated dementia 8%) and 64% among noncomplainers (asymptomatic neurocognitive impairment 60%, mild neurocognitive disorders 4%, and HIV-associated dementia 0%; P < 0.001). A score of 14 points or less on the HIV dementia scale yielded a positive predictive value of HANDs of 92% in complainers and 82% in noncomplainers. The prevalence of HANDs is high even in long-standing aviremic HIV-positive patients. However, HANDs without functional repercussion in daily life (asymptomatic neurocognitive impairment) is the most frequent subtype observed. In this population, the HIV dementia scale with a cutoff of 14 points or less seems to provide a useful tool to screen for the presence of HANDs.

P07-11 LB. Impact of highly active antiretroviral therapy on cell-free and cell-associated HIV-1 in cervicovaginal secretions and blood

Results Cell-free HIV-1 RNA was frequently detected in CVS from patients viremic for HIV RNA in plasma but was unusual in aviremic patients (75% versus 16%, and mean = 5921 copies/ml versus 2696 copies/ml, respectively, P < 0.001). Levels of HIV-1 RNA were positively correlated in CVS and plasma (ρ = 0.7, P < 0.001). CVS contains low T lymphocytes quantities (mean = 120 CD4+ cells/ml and 133 CD8+ cells/ml) and CVS-derived CD4+ T cells are mostly memory and activated lymphocytes (CD45RA-, HLA-DR+, CD38+, CD69+). Those cells were strikingly different from blood CD4+ T cells with a phenotype exhibiting a mucosal profile with higher expression of CD103 combined with lower expression of CCR7. Cell-associated HIV-1 RNA was detectable in only 3/51 CVS including 2 from viremic patients, whereas 28/51 plasma cell-culture supernatants were positive. Levels of cell-associated HIV-1 RNA were higher in blood samples of viremic individuals than in undetectable subjects (P = 0.01).

Expression of latent human immunodeficiency type 1 is induced by novel and selective histone deacetylase inhibitors

A family of histone deacetylases (HDACs) mediates chromatin remodeling, and repression of gene expression. Deacetylation of histones within the HIV-1 long terminal repeat (LTR) by HDACs plays a key role in the maintenance of latency, whereas acetylation of histones about the LTR is linked to proviral expression and escape of HIV from latency. Global HDAC inhibition may adversely affect host gene expression, leading to cellular toxicities. Potent inhibitors selective for HDACs that maintain LTR repression could be ideal antilatency therapeutics. We investigated the ability of selective HDAC inhibitors to de-repress the HIV-1 LTR in both a cell line model of latency and in resting CD4 T cells isolated from patients who were aviremic on antiretroviral therapy (ART). We found that inhibition of class I HDACs increased acetylation of histones at the LTR, but that LTR chromatin was unaffected by class II HDAC inhibitors. In a latently infected cell line, inhibitors selective for class I HDACs were more efficient activators of the LTR than inhibitors that target class II HDACs. Class I HDAC inhibitors were strikingly efficient inducers of virus outgrowth from resting CD4 T cells of aviremic patients, whereas HIV was rarely recovered from patient's cells exposed to class II HDAC inhibitors. Further development of selective HDAC inhibitors as part of a clinical strategy to target persistent HIV infection is warranted.

CpG Methylation Controls Reactivation of HIV from Latency

DNA methylation of retroviral promoters and enhancers localized in the provirus 5′ long terminal repeat (LTR) is considered to be a mechanism of transcriptional suppression that allows retroviruses to evade host immune responses and antiretroviral drugs. However, the role of DNA methylation in the control of HIV-1 latency has never been unambiguously demonstrated, in contrast to the apparent importance of transcriptional interference and chromatin structure, and has never been studied in HIV-1-infected patients. Here, we show in an in vitro model of reactivable latency and in a latent reservoir of HIV-1-infected patients that CpG methylation of the HIV-1 5′ LTR is an additional epigenetic restriction mechanism, which controls resistance of latent HIV-1 to reactivation signals and thus determines the stability of the HIV-1 latency. CpG methylation acts as a late event during establishment of HIV-1 latency and is not required for the initial provirus silencing. Indeed, the latent reservoir of some aviremic patients contained high proportions of the non-methylated 5′ LTR. The latency controlled solely by transcriptional interference and by chromatin-dependent mechanisms in the absence of significant promoter DNA methylation tends to be leaky and easily reactivable. In the latent reservoir of HIV-1-infected individuals without detectable plasma viremia, we found HIV-1 promoters and enhancers to be hypermethylated and resistant to reactivation, as opposed to the hypomethylated 5′ LTR in viremic patients. However, even dense methylation of the HIV-1 5′LTR did not confer complete resistance to reactivation of latent HIV-1 with some histone deacetylase inhibitors, protein kinase C agonists, TNF-α, and their combinations with 5-aza-2deoxycytidine: the densely methylated HIV-1 promoter was most efficiently reactivated in virtual absence of T cell activation by suberoylanilide hydroxamic acid. Tight but incomplete control of HIV-1 latency by CpG methylation might have important implications for strategies aimed at eradicating HIV-1 infection.

Programmed death (PD)-1 molecule and its ligand PD-L1 distribution among memory CD4 and CD8 T cell subsets in human immunodeficiency virus-1-infected individuals

Human immunodeficiency virus (HIV)-1 causes T cell anergy and affects T cell maturation. Various mechanisms are responsible for impaired anti-HIV-1-specific responses: programmed death (PD)-1 molecule and its ligand PD-L1 are negative regulators of T cell activity and their expression is increased during HIV-1 infection. This study examines correlations between T cell maturation, expression of PD-1 and PD-L1, and the effects of their blockade. Peripheral blood mononuclear cells (PBMC) from 24 HIV-1(+) and 17 uninfected individuals were phenotyped for PD-1 and PD-L1 expression on CD4(+) and CD8(+) T cell subsets. The effect of PD-1 and PD-L1 blockade on proliferation and interferon (IFN)-gamma production was tested on eight HIV-1(+) patients. Naive (CCR7(+)CD45RA(+)) CD8(+) T cells were reduced in HIV-1 aviraemic (P = 0.0065) and viraemic patients (P = 0.0130); CD8 T effector memory subsets [CCR7(-)CD45RA(-)(T(EM))] were increased in HIV-1(+) aviraemic (P = 0.0122) and viraemic (P = 0.0023) individuals versus controls. PD-1 expression was increased in CD4 naive (P = 0.0496), central memory [CCR7(+)CD45RA(-) (T(CM)); P = 0.0116], T(EM) (P = 0.0037) and CD8 naive T cells (P = 0.0133) of aviraemic HIV-1(+) versus controls. PD-L1 was increased in CD4 T(EMRA) (CCR7(-)CD45RA(+), P = 0.0119), CD8 T(EM) (P = 0.0494) and CD8 T(EMRA) (P = 0.0282) of aviraemic HIV-1(+)versus controls. PD-1 blockade increased HIV-1-specific proliferative responses in one of eight patients, whereas PD-L1 blockade restored responses in four of eight patients, but did not increase IFN-gamma-production. Alteration of T cell subsets, accompanied by increased PD-1 and PD-L1 expression in HIV-1 infection contributes to anergy and impaired anti-HIV-1-specific responses which are not rescued when PD-1 is blocked, in contrast to when PD-L1 is blocked, due possibly to an ability to bind to receptors other than PD-1.

Hepatitis C Virus Coinfection Does Not Influence the CD4 Cell Recovery in HIV-1-Infected Patients With Maximum Virologic Suppression

Conflicting data exist whether hepatitis C virus (HCV) affects the CD4 cell recovery in patients with HIV starting antiretroviral treatment. To investigate the influence of HCV coinfection on the CD4 recovery in patients with maximum virologic suppression within the EuroSIDA cohort. Patients tested for anti-HCV antibodies and with at least 2 consecutive HIV viral loads (VLs) <50 copies per milliliter after starting combination antiretroviral therapy were eligible for inclusion. For each pair of VL <50 copies per milliliter, the annual change in CD4 count was calculated and compared between (1) HCV-seronegative vs. HCV-seropositive patients, (2) HCV genotypes 1-4 in HCV-RNA+ patients, and (3) viremic vs. aviremic (HCV-RNA < 615 IU/mL) in HCV-seropositive patients. Results were adjusted for known confounders. Four thousand two hundred eight patients were included, representing 39,474 pairs of HIV VL measurements with VL <50 copies per milliliter and 12,492 person-years of follow-up. The unadjusted annual change in CD4 count for HCV-seropositive and HCV-seronegative patients was 35.5 cells per milliliter (95% confidence interval 27.2 to 43.9) and 38.3 cells per milliliter (95%confidence interval 34.8 to 41.9), respectively. After adjustment, there was no difference in CD4 change when comparing, according to HCV serostatus (P = 0.17), between genotypes (P = 0.23) or when comparing HCV viremic vs. aviremic patients (P = 0.57). Adjusting additionally for HCV treatment and HCV-RNA VL did not change the findings. HCV serostatus did not influence the CD4 recovery in patients with HIV with maximum virologic suppression after starting combination antiretroviral therapy. Furthermore, no difference in CD4 gain was found when comparing distinct HCV genotypes in HCV-RNA+ patients or when comparing HCV viremic vs. aviremic HCV-seropositive patients.

A Limited Group of Class I Histone Deacetylases Acts To Repress Human Immunodeficiency Virus Type 1 Expression

Silencing of the integrated human immunodeficiency virus type 1 (HIV-1) genome in resting CD4(+) T cells is a significant contributor to the persistence of infection, allowing the virus to evade both immune detection and pharmaceutical attack. Nonselective histone deacetylase (HDAC) inhibitors are capable of inducing expression of quiescent HIV-1 in latently infected cells. However, potent global HDAC inhibition can induce host toxicity. To determine the specific HDACs that regulate HIV-1 transcription, we evaluated HDAC1 to HDAC11 RNA expression and protein expression and compartmentalization in the resting CD4(+) T cells of HIV-1-positive, aviremic patients. HDAC1, -3, and -7 had the highest mRNA expression levels in these cells. Although all HDACs were detected in resting CD4(+) T cells by Western blot analysis, HDAC5, -8, and -11 were primarily sequestered in the cytoplasm. Using chromatin immunoprecipitation assays, we detected HDAC1, -2, and -3 at the HIV-1 promoter in Jurkat J89GFP cells. Targeted inhibition of HDACs by small interfering RNA demonstrated that HDAC2 and HDAC3 contribute to repression of HIV-1 long terminal repeat expression in the HeLa P4/R5 cell line model of latency. Together, these results suggest that HDAC inhibitors specific for a limited number of class I HDACs may offer a targeted approach to the disruption of persistent HIV-1 infection.

Expression of Latent HIV Induced by the Potent HDAC Inhibitor Suberoylanilide Hydroxamic Acid

Histone deacetylases (HDACs) act on histones within the nucleosome-bound promoter of human immunodeficiency virus type 1 (HIV-1) to maintain proviral latency. HDAC inhibition leads to promoter expression and the escape of HIV from latency. We evaluated the ability of the potent inhibitor recently licensed for use in oncology, suberoylanilide hydroxamic acid (SAHA; Vorinostat), selective for Class I HDACs, to induce HIV promoter expression in cell lines and virus production from the resting CD4(+) T cells of antiretroviral-treated, aviremic HIV-infected patients. In J89, a Jurkat T cell line infected with a single HIV genome encoding the enhanced green fluorescence protein (EGFP) within the HIV genome, SAHA induced changes at nucleosome 1 of the HIV promoter in chromatin immunoprecipitation (ChIP) assays in concert with EGFP expression. In the resting CD4(+) T cells of antiretroviral-treated, aviremic HIV-infected patients clinically achievable exposures to SAHA induced virus outgrowth ex vivo. These results suggest that potent, selective HDAC inhibitors may allow improved targeting of persistent proviral HIV infection, and define parameters for in vivo studies using SAHA.

Close association of CD8+/CD38bright with HIV‐1 replication and complex relationship with CD4+ T‐cell count

Measuring lymphocyte activation provides information in addition to CD4(+) T-cell count for immune monitoring of HIV-1 infected patients. CD38 is a well-established activation marker that is generally analyzed on the whole population of CD8(+) T-cells. Focusing specifically on CD38 high expression (CD8(+)/CD38(bright)) may be an interesting surrogate gating strategy because CD38(bright) characterizes principally activated memory cells. CD8(+)/CD38(bright) was investigated in 1,353 HIV-1 infected patients over a one-year period to establish relevant cutoff values and clarify the relationships of this marker with HIV-1 RNA viral load (VL) and CD4(+) T-cell count. The CD8(+)/CD38(bright) (>8,500 CD38 binding site per cells) is well correlated with HIV-1 VL (r = 0.87, P < 0.001) in this longitudinal follow-up of nonimmunodepressed patients that initiated antiviral therapy (ART). In aviremic patients on ART, the marker was highly predictive of VL rebound (sensitivity 93%, specificity 64% for a VL level of detection >200 copies/ml). While the CD8(+)/CD38(bright) moderately correlated with CD4(+) T-cell count independently of the VL (r = -0.37, P < 0.001), it increased dramatically in aviremic patient groups that exhibited profound CD4(+) T-cell depletion (median 39% for CD4(+) T-cell counts <50/mm(3)). This result indicates that other additional immunological and/or viral factors than readily detectable HIV-1 replication appears to be involved in T-cell activation of immunodepressed individuals. CD8(+)/CD38(bright) is an effective marker for monitoring T-cell activation, which is a central factor of HIV-1 pathogenesis. This gating strategy requires only a single additional staining in conventional four color CD4 protocols.

Hexamethylbisacetamide and Disruption of Human Immunodeficiency Virus Type 1 Latency in CD4+T Cells

Novel therapeutic approaches are needed to attack persistent proviral human immunodeficiency type 1 (HIV-1) infection. Hexamethylbisacetamide (HMBA), a hybrid bipolar compound, induces expression of the HIV-1 promoter in the long terminal repeat (LTR) region in a Tat-independent manner but mimics the effect of Tat, overcoming barriers to LTR expression and increasing the processivity of LTR transcription complexes. We studied alterations in cellular factors and their LTR occupancy induced by HMBA in models of latent HIV-1 infection. We measured the induction of viral outgrowth by HMBA in resting CD4(+) T cells from aviremic HIV-1-infected donors. HMBA induced outgrowth of HIV-1 from resting CD4(+) T cells recovered from aviremic patients treated with antiretroviral therapy (ART). HMBA triggered cyclin-dependent kinase 9 (CDK9) recruitment to the LTR, a key factor in the induction of efficient HIV-1 expression, via an unexpected interaction with the transcription factor Sp1. The availability of Sp1 and Sp1 DNA binding sites were necessary for HMBA-induced CDK9 recruitment and LTR expression. HMBA signaling via both protein kinase C mu and phosphatidylinositol 3-kinase appeared to contribute to LTR induction. The novel mechanism through which HMBA disrupts latent HIV-1 infection involves 2 cellular kinases that may be therapeutically exploited to induce expression of persistent proviral HIV-1.

Planned Multiple Exposures to Autologous Virus in HIV Type 1-Infected Pediatric Populations Increases HIV-Specific Immunity and Reduces HIV Viremia

We tested to determine if planned multiple exposures to autologous HIV in pediatric patients with HIV-1 infection will induce cellular immunity that controls viremia. A prospective multicenter study of aviremic pediatric patients on highly active antiretroviral therapy who underwent progressively longer antiretroviral treatment interruptions in cycles starting with 3 days, increasing by 2 days in length each consecutive cycle, was conducted. Eight individuals became viremic and reached Cycle 13 or greater with an "off-therapy" interval of >or=27 days. HIV-specific interferon-gamma (IFN-gamma) production to inactivated HIV and vaccinia vectors expressing gag, env, nef, and pol increased (>10-fold) from baseline in six of eight subjects. The HIV-specific lymphoproliferative response as measured by the median stimulation index (SI) increased in the treatment group from 1 at baseline to 16, 12, 4, and 3 at Cycles 7, 10, 13, and 17, respectively. Median plasma RNA levels peaked at Cycle 7 (4.45 log) and declined to levels <10(4) cp/ml after Cycle 10 (4.1, 3.5, and 3.4 at Cycles 10, 13, and 17). In a subset of five patients who reached Cycle 17, HIV-specific IFN-gamma frequencies were 4- to 30-fold higher and median RNA levels were 0.32-2.10 (median 1.3) log lower than at comparable days off treatment at Cycle 8 (17 days off therapy). A second group of children, not undergoing drug interruption, did not develop significant increases in either HIV-specific IFN-gamma production or SI. Increased HIV-specific immune responses and decreased HIV RNA were seen in those children who have had >10 cycles of antiretroviral discontinuations of increasing durations acting as autologous virus vaccinations. Other studies may have failed due to an insufficient number of exposures to HIV; most of the studies had fewer than six drug interruptions.

Immunophenotypic patterns of CD8 + T cell subsets expressing CD8αα and IL-7Rα in viremic, aviremic and slow progressor HIV-1-infected subjects

Evidence from animal models suggests that the expression of CD8αα homodimer on CD8 + T cells plays a key role in the generation of long-lived memory cells. Here, we studied the quantitative alterations of CD8 + T cell subsets expressing CD8αα, interleukin-7 receptor (IL-7Rα) and activation markers in HIV-1-infected individuals including aviremic, viremic and slow progressor subjects using eight-color flow cytometry. Compared to slow progressor subjects, expression of CD8αα was significantly reduced in aviremic and viremic patients and this reduction occurred mainly within central memory cell subsets and not in naive and effector memory compartments. Persistence of antigenemia leads to IL-7Rα loss mainly on central and pre-terminal memory CD8 + T cell subsets in viremic patients but not in slow progressor subjects. Compared to aviremic and viremic patients, slow progressor subjects had lower levels of IL-7 and reduced activated cells. The expression of CD8αα was not significantly related to IL-7Rα although negative associations were evidenced within all CD8 + T cell subsets. Collectively, these results further advance the characterization of immunophenotypic patterns of CD8 + T cell subsets expressing CD8αα/IL-7Rα and provide new insights into the ability of HIV-1 infection to alter memory cell population.

Expression of PD-L1, a marker of disease status, is not reduced by HAART in aviraemic patients

Anergy and defective immune responses are characteristic of chronic HIV-1 infection. The programmed death 1 (PD-1)/PD-1 ligand (PD-L1) pathway appears to be involved in downregulating T-cell functionality. We found raised levels of PD-L1 in aviraemic chronically infected HIV-1-positive patients, which may contribute to incomplete immune reconstitution after treatment with HAART.

Slow disease progression and robust therapy-mediated CD4+ T-cell recovery are associated with efficient thymopoiesis during HIV-1 infection

AbstractIn chronic HIV infection, most untreated patients lose naive CD4+ and CD8+ T cells, whereas a minority preserve them despite persistent high viremia. Although antiretroviral therapy (ART)–mediated viral suppression generally results in a rise of naive and total CD4+ T cells, certain patients experience very little or no T-cell reconstitution. High peripheral T-cell activation has been linked to poor clinical outcomes, interfering with previous evaluations of thymic function in disease progression and therapy-mediated T-cell recovery. To circumvent this, we used the sj/βTREC ratio, a robust index of thymopoiesis that is independent of peripheral T-cell proliferation, to evaluate the thymic contribution to the preservation and restoration of naive CD4+ T cells. We show that the loss of naive and total CD4+ T cells is the result of or is exacerbated by a sustained thymic defect, whereas efficient thymopoiesis supports naive and total CD4+ T-cell maintenance in slow progressor patients. In ART-treated patients, CD4+ T-cell recovery was associated with the normalization of thymopoiesis, whereas the thymic defect persisted in aviremic patients who failed to recover CD4+ T-cell counts. Overall, we demonstrate that efficient thymopoiesis is key in the natural maintenance and in therapy-mediated recovery of naive and total CD4+ T cells.

Expression of Immune Memory Markers CD8 α α and Interleukin−7 Receptor on CD8+ T Cell Subsets among HIV−1 Infected Patients.

Evidence from animal models suggests that the expression of CD8α α homodimer on CD8+ T-cells plays a key role in the generation of long-lived memory cells. However, very little information is available in the human clinical setting. Here, we examined immunophenotypic patterns of CD8+ T-cell subsets expressing CD8α α with other markers involved in generating and maintaining memory cells such as interleukin-7 receptor (IL-7Rα ) and circulating levels of IL-7 and IL-15, in three well-defined groups of human immunodeficiency virus-1 (HIV-1)-infected individuals including aviremic (n=15), viremic (n=31) and slow-progressor (n=15). In addition, immunophenotypic patterns were correlated with immune activation markers (CD38/HLA-DR), which are known to be an important factor in HIV-1 disease pathogenesis. Cell-surface expression of CD8α α , IL-7Rα and CD38/HLA-DR on CD8+ naïve, central memory, pre-terminal and terminal effector memory T-cells was measured by eight-color flow cytometry on freshly peripheral blood samples. IL-7 and IL-15 levels were measured by ELISA and viral loads were assessed by PCR. Group differences in the CD8+ T-cell subsets expressing each antigen tested were evaluated using the unpaired nonparametric Mann Whitney U test. Correlations were determined by Spearman's correlation tests. Compared to slow-progressor subjects, expression of CD8α α was significantly reduced in aviremic and viremic patients and this reduction occurred mainly within naïve and central memory T-cell subsets and not in effector memory compartments. In contrast, persistent antigenemia in viremic patients appeared to lead to IL-7Rα loss mainly on central and effector memory subsets and not on naive T-cells. Compared to aviremic and viremic patients, slow-progressor subjects had lower levels of circulating IL-7, normal levels of IL-15, CD8α α and IL-7Rα , and reduced activated T-cells. Overall, expression of CD8α α was not significantly related to IL-7Rα although negative associations were evidenced within all CD8+ T-cell subsets. However, in viremic patients, naïve and central memory cell subsets expressing CD8α α were positively correlated with viral load but not with CD8+ T-cell subsets expressing immune activation markers. Together, these results provide new insights into the role of CD8α α /IL-7Rα along with immune activation markers in maintaining memory populations during HIV-1 infection. The inter-relationships between these immune memory markers require further investigations, which may help understanding the mechanisms of antiviral control.

Characterization of the defective interaction between a subset of natural killer cells and dendritic cells in HIV-1 infection

In this study, we demonstrate that the in vitro interactions between a CD56neg/CD16pos (CD56neg) subset of natural killer (NK) cells and autologous dendritic cells (DCs) from HIV-1–infected viremic but not aviremic individuals are markedly impaired and likely interfere with the development of an effective immune response. Among the defective interactions are abnormalities in the process of reciprocal NK–DC activation and maturation as well as a defect in the NK cell–mediated editing or elimination of immature DCs (iDCs). Notably, the lysis of mature DCs (mDCs) by autologous NK cells was highly impaired even after the complete masking of major histocompatibility complex I molecules, suggesting that the defective elimination of autologous iDCs is at the level of activating NK cell receptors. In this regard, the markedly impaired expression/secretion and function of NKp30 and TNF-related apoptosis-inducing ligand, particularly among the CD56neg NK cell subset, largely accounts for the highly defective NK cell–mediated lysis of autologous iDCs. Moreover, mDCs generated from HIV-1 viremic but not aviremic patients are substantially impaired in their ability to secrete interleukin (IL)-10 and -12 and to prime the proliferation of neighboring autologous NK cells, which, in turn, fail to secrete adequate amounts of interferon-γ.

Switch from inhibitory to activating NKG2 receptor expression in HIV-1 infection: lack of reversion with highly active antiretroviral therapy

HIV-1 infection is characterized by increase in inhibitory receptors and loss of activating receptors on natural killer (NK) cells, resulting in loss of cell activity. Exceptionally, for an inhibitory receptor, the proportion of NK cells bearing CD94-NKG2A decreases during HIV-1 infection. It is not understood whether HIV-1 itself or other concomitant infections drive these changes. To investigate the relationship between HIV-1 viraemia and changes in C-type lectin-like receptor expression in NK cells and to investigate the effect of highly active antiretroviral therapy (HAART) on these changes. Three cohorts of patients were studied: (1) before, during and after treatment interruption in aviraemic and viraemic patients receiving HAART (n = 15); (2) HIV-1-positive treatment-naive individuals (n = 13); and (3) HIV-1-positive individuals receiving successful HAART for a minimum of 1 year without interruption (n = 11). Flow cytometry was used to study the expression of NKG2A before and after treatment interruption and to define expanded populations of NK cells in untreated and treated HIV-1-positive individuals. Assays were performed in vitro to assess the cytotoxicity of the expanded populations. Increases in plasma HIV-1 RNA during treatment interruption in aviraemic HAART-treated individuals did not influence the proportion of NK cells carrying the complex CD94-NKG2A. Loss of NKG2A NK cells corresponded to the dramatic expansion of a distinct population of cells expressing a functional activating CD94-NKG2C receptor with skewed expression of killer cell immunoglobulin-like receptor family and natural cytotoxicity receptors. Changes in the NK cell repertoire during HIV-1 infection were not a result of HIV-1 viraemia alone but resembled those associated with concomitant infections.

Interleukin-15 enhances the secretion of IFN-γ and CC chemokines by natural killer cells from HIV viremic and aviremic patients

Several lines of evidence documented a renewed interest in the role of natural killer (NK) cells in the innate immune control of HIV infection and disease progression. To further assess the role of NK cells as target for immunotherapy in HIV infection, we evaluated the priming effect of interleukin (IL)-15 on freshly isolated human peripheral NK cells, from viremic and aviremic HIV-infected patients, measuring the production of IFN-γ and CC chemokines. In vitro IL-15 priming induced a significant increase of IFN-γ production in both viremic and aviremic patients. IL-15 stimulated NK cells producing CC chemokine quantities that are reported to be capable of inhibiting HIV infection and replication. This priming effect is observed both in viral suppressed patients after antiretroviral therapy, and in viremic subjects with progressive HIV infection. The combination of IL-15 plus IL-12 is the most potent costimulus for CD69 expression and production of CC chemokines by NK cells. These findings indicate that NK cells are an important target for immunotherapeutic agents and provide additional pre-clinical data supporting the great potential of IL-15 in the immune-based interventions in HIV disease.

The effect of combination antiretroviral therapy on CD5 B‐ cells, B‐cell activation and hypergammaglobulinaemia in HIV‐1‐infected patients

This study assessed B-cell activation, CD5 B-cells and circulating immunoglobulin levels in HIV-infected patients treated with combination antiretroviral therapy (CART). Measurement of plasma immunoglobulin levels and electrophoresis of plasma proteins, and analyses of total numbers of B-cells and B-cells expressing CD 38 and CD5 in whole blood, were undertaken in 47 consecutive HIV-1-infected patients attending an out-patient clinic. All HIV-infected patients had similar percentages and numbers of B-cells. Proportions of CD5 B-cells in all HIV-infected patients were significantly lower than those in HIV-negative controls. Aviraemic HIV-infected patients on CART had lower percentages of CD5, CD 38 and CD5 CD 38 B-cell subsets and lower plasma levels of immunoglobulin G (IgG) and immunoglobulin A (IgA) than viraemic HIV-infected patients (untreated or on CART). However, 33-37% of aviraemic HIV-infected patients had IgG and IgA levels above the 95th percentile of the normal range defined in HIV-seronegative donors. In aviraemic HIV-infected patients, plasma IgA levels correlated only with proportions of activated (CD 38) B-cells. IgG levels did not correlate with the proportions of B-cell subsets or any marker of HIV disease activity. Monoclonal immunoglobulins were not detected in any plasma sample. Aviraemic HIV-infected patients on CART have lower plasma levels of IgG and IgA than viraemic HIV-infected patients, but levels are often above the normal range. CD5 B-cell numbers are depressed, so these cells are unlikely to contribute to hypergammaglobulinaemia in HIV-infected patients.