Low CD4+ T-cell counts in HIV patients receiving effective antiretroviral therapy are associated with CD4+ T-cell activation and senescence but not with lower effector memory T-cell function

HIV-1 Integrase T218I/S Polymorphisms Do Not Reduce HIV-1 Integrase Inhibitors' Phenotypic Susceptibility

The recently Food and Drug Administration (FDA)-approved cabotegravir (CAB) has demonstrated efficacy as an antiretroviral agent for HIV treatment and prevention, becoming an important tool to stop the epidemic in the United States of America (USA). However, the effectiveness of CAB can be compromised by the presence of specific integrase natural polymorphisms, including T97A, L74M, M50I, S119P, and E157Q, particularly when coupled with the primary drug-resistance mutations G140S and Q148H. CAB's recent approval as a pre-exposure prophylaxis (PrEP) may increase the number of individuals taking CAB, which, at the same time, could increase the number of epidemiological implications. In this context, where resistance mutations, natural polymorphisms, and the lack of drug-susceptibility studies prevail, it becomes imperative to comprehensively investigate concerns related to the use of CAB. We used molecular and cell-based assays to assess the impact of T218I and T218S in the context of major resistance mutations G140S/Q148H on infectivity, integration, and resistance to CAB. Our findings revealed that T218I and T218S, either individually or in combination with G140S/Q148H, did not significantly affect infectivity, integration, or resistance to CAB. Notably, these polymorphisms also exhibited neutrality concerning other widely used integrase inhibitors, namely raltegravir, elvitegravir, and dolutegravir. Thus, our study suggests that the T218I and T218S natural polymorphisms are unlikely to undermine the effectiveness of CAB as a treatment and PrEP strategy.

The TLR7/IRF-5 axis sensitizes memory CD4+ T cells to Fas-mediated apoptosis during HIV-1 infection

HIV-1 infection is characterized by inflammation and a progressive decline in CD4+ T cell count. Despite treatment with antiretroviral therapy (ART), the majority of people living with HIV (PLWH) maintain residual levels of inflammation, a low degree of immune activation, and higher sensitivity to cell death in their memory CD4+ T cell compartment. To date, the mechanisms responsible for this high sensitivity remain elusive. We have identified the transcription factor IRF-5 to be involved in impairing the maintenance of murine CD4+ T cells during chronic infection. Here, we investigate whether IRF-5 also contributes to memory CD4+ T cell loss during HIV-1 infection. We show that TLR7 and IRF-5 were upregulated in memory CD4+ T cells from PLWH, when compared with naturally protected elite controllers and HIVfree participants. TLR7 was upstream of IRF-5, promoting Caspase 8 expression in CD4+ T cells from ART HIV-1+ but not from HIVfree donors. Interestingly, the TLR7/IRF-5 axis acted synergistically with the Fas/FasL pathway, suggesting that TLR7 and IRF-5 expression in ART HIV-1+ memory CD4+ T cells represents an imprint that predisposes cells to Fas-mediated apoptosis. This predisposition could be blocked using IRF-5 inhibitory peptides, suggesting IRF-5 blockade as a possible therapy to prevent memory CD4+ T cell loss in PLWH.

Inflammasomes as mediators of inflammation in HIV-1 infection

Human immunodeficiency virus type 1 (HIV-1) infection is a chronic disease without a known cure. The advent of effective antiretroviral therapy (ART) has enabled people with HIV (PWH) to have significantly prolonged life expectancies. As a result, morbidity and mortality associated with HIV-1 infection have declined considerably. However, these individuals experience chronic systemic inflammation whose multifaceted etiology is associated with other numerous comorbidities. Inflammasomes are vital mediators that contribute to inflammatory signaling in HIV-1 infection. Here, we provide an overview of the inflammatory pathway that underlies HIV-1 infection, explicitly highlighting the role of the NLRP3 inflammasome. We also delineate the current literature on inflammasomes and the therapeutic targeting strategies aimed at the NLRP3 inflammasome to moderate HIV-1 infection-associated inflammation. Here we describe the NLRP3 inflammasome as a key pathway in developing novel therapeutic targets to block HIV-1 replication and HIV-1-associated inflammatory signaling. Controlling the inflammatory pathways is critical in alleviating the morbidities and mortality associated with chronic HIV-1 infection in PWH.

Methadone use is associated with increased levels of sCD14, immune activation, and inflammation during suppressed HIV infection

Opioid use has negative effects on immune responses and may impair immune reconstitution in persons living with HIV (PLWH) infection undergoing antiretroviral treatment (ART). The effects of treatment with μ opioid receptor (MOR) agonists (e.g., methadone, MET) and antagonists (e.g., naltrexone, NTX) on immune reconstitution and immune activation in ART-suppressed PLWH have not been assessed in-depth. We studied the effects of methadone or naltrexone on measures of immune reconstitution and immune activation in a cross-sectional community cohort of 30 HIV-infected individuals receiving suppressive ART and medications for opioid use disorder (MOUD) (12 MET, 8 NTX and 10 controls). Plasma markers of inflammation and immune activation were measured using ELISA, Luminex, or Simoa. Plasma IgG glycosylation was assessed using capillary electrophoresis. Cell subsets and activation were studied using whole blood flow cytometry. Individuals in the MET group, but no in the NTX group, had higher plasma levels of inflammation and immune activation markers than controls. These markers include soluble CD14 (an independent predictor of morbidity and mortality during HIV infection), proinflammatory cytokines, and proinflammatory IgG glycans. This effect was independent of time on treatment. Our results indicate that methadone-based MOUD regimens may sustain immune activation and inflammation in ART-treated HIV-infected individuals. Our pilot study provides the foundation and rationale for future longitudinal functional studies of the impact of MOUD regimens on immune reconstitution and residual activation after ART-mediated suppression.

Inflammation, Immune Senescence, and Dysregulated Immune Regulation in the Elderly

An optimal immune response requires the appropriate interaction between the innate and the adaptive arms of the immune system as well as a proper balance of activation and regulation. After decades of life, the aging immune system is continuously exposed to immune stressors and inflammatory assaults that lead to immune senescence. In this review, we will discuss inflammaging in the elderly, specifically concentrating on IL-6 and IL-1b in the context of T lymphocytes, and how inflammation is related to mortality and morbidities, specifically cardiovascular disease and cancer. Although a number of studies suggests that the anti-inflammatory cytokine TGF-b is elevated in the elderly, heightened inflammation persists. Thus, the regulation of the immune response and the ability to return the immune system to homeostasis is also important. Therefore, we will discuss cellular alterations in aging, concentrating on senescent T cells and CD4+ CD25+ FOXP3+ regulatory T cells (Tregs) in aging

Immune Recovery Following Autologous Hematopoietic Stem Cell Transplantation in HIV-Related Lymphoma Patients on the BMT CTN 0803/AMC 071 Trial

We report a first in-depth comparison of immune reconstitution in patients with HIV-related lymphoma following autologous hematopoietic cell transplant (AHCT) recipients (n=37, lymphoma, BEAM conditioning), HIV(-) AHCT recipients (n=30, myeloma, melphalan conditioning) at 56, 180, and 365 days post-AHCT, and 71 healthy control subjects. Principal component analysis showed that immune cell composition in HIV(+) and HIV(-) AHCT recipients clustered away from healthy controls and from each other at each time point, but approached healthy controls over time. Unsupervised feature importance score analysis identified activated T cells, cytotoxic memory and effector T cells [higher in HIV(+)], and naïve and memory T helper cells [lower HIV(+)] as a having a significant impact on differences between HIV(+) AHCT recipient and healthy control lymphocyte composition (p<0.0033). HIV(+) AHCT recipients also demonstrated lower median absolute numbers of activated B cells and lower NK cell sub-populations, compared to healthy controls (p<0.0033) and HIV(-) AHCT recipients (p<0.006). HIV(+) patient T cells showed robust IFNγ production in response to HIV and EBV recall antigens. Overall, HIV(+) AHCT recipients, but not HIV(-) AHCT recipients, exhibited reconstitution of pro-inflammatory immune profiling that was consistent with that seen in patients with chronic HIV infection treated with antiretroviral regimens. Our results further support the use of AHCT in HIV(+) individuals with relapsed/refractory lymphoma.

Markers of T Cell Exhaustion and Senescence and Their Relationship to Plasma TGF-β Levels in Treated HIV+ Immune Non-responders

Background: Immune non-responders (INR) are HIV+, ART-controlled (>2 yrs) people who fail to reconstitute their CD4 T cell numbers. Systemic inflammation and markers of T cell senescence and exhaustion are observed in INR. This study aims to investigate T cell senescence and exhaustion and their possible association with soluble immune mediators and to understand the immune profile of HIV-infected INR. Selected participants were <50 years old to control for the confounder of older age. Methods: Plasma levels of IL-6, IP10, sCD14, sCD163, and TGF-β and markers of T cell exhaustion (PD-1, TIGIT) and senescence (CD57, KLRG-1) were measured in ART-treated, HIV+ participants grouped by CD4 T cell counts (n = 63). Immune parameters were also measured in HIV-uninfected, age distribution-matched controls (HC; n = 30). Associations between T cell markers of exhaustion and senescence and plasma levels of immune mediators were examined by Spearman rank order statistics. Results: Proportions of CD4 T cell subsets expressing markers of exhaustion (PD-1, TIGIT) and senescence (CD57, KLRG-1) were elevated in HIV+ participants. When comparing proportions between INR and IR, INR had higher proportions of CD4 memory PD-1+, EM CD57+, TEM TIGIT+ and CD8 EM and TEM TIGIT+ cells. Plasma levels of IL-6, IP10, and sCD14 were elevated during HIV infection. IP10 was higher in INR. Plasma TGF-β levels and CD4 cycling proportions of T regulatory cells were lower in INR. Proportions of CD4 T cells expressing TIGIT, PD-1, and CD57 positively correlated with plasma levels of IL-6. Plasma levels of TGF-β negatively correlated with proportions of TIGIT+ and PD-1+ T cell subsets. Conclusions: INR have lower levels of TGF-β and decreased proportions of cycling CD4 T regulatory cells and may have difficulty controlling inflammation. IP10 is elevated in INR and is linked to higher proportions of T cell exhaustion and senescence seen in INR.

Cell-Associated HIV-1 Unspliced-to-Multiply-Spliced RNA Ratio at 12 Weeks of ART Predicts Immune Reconstitution on Therapy

Human immunodeficiency virus (HIV) infection is currently managed by antiretroviral drugs, which block virus replication and promote immune restoration. However, the latter effect is not universal, with a proportion of infected individuals failing to sufficiently reconstitute their immune function despite a successful virological response to antiretroviral therapy (ART).

Incomplete restoration of CD4⁺ T-cell counts on antiretroviral therapy (ART) is a major predictor of HIV-related morbidity and mortality. To understand the possible mechanisms behind this poor immunological response despite viral suppression, we longitudinally measured more than 50 virological and immunological biomarkers in a cohort of HIV-infected individuals at several time points during the first 96 weeks of virologically suppressive ART. No baseline virological or immunological marker was predictive of the degree of immune reconstitution. However, the cell-associated HIV-1 unspliced-to-multiply-spliced (US/MS) RNA ratio at 12 weeks of ART positively correlated with markers of CD4⁺ T-cell activation and apoptosis and negatively predicted both the absolute and relative CD4⁺ T-cell counts at 48 and 96 weeks. A higher US/MS RNA ratio may reflect the higher frequency of productively infected cells that could exert pressure on the immune system, contributing to persistent immune activation and apoptosis and subsequently to a poor immunological response to ART.

Immunology of EBV-Related Lymphoproliferative Disease in HIV-Positive Individuals

Epstein-Bar virus (EBV) can directly cause lymphoproliferative disease (LPD), including AIDS-defining lymphomas such as Burkitt’s lymphoma and other non-Hodgkin lymphomas (NHL), as well as human immunodeficiency virus (HIV)-related Hodgkin lymphoma (HL). The prevalence of EBV in HL and NHL is elevated in HIV-positive individuals compared with the general population. Rates of incidence of AIDS-defining cancers have been declining in HIV-infected individuals since initiation of combination anti-retroviral therapy (cART) use in 1996. However, HIV-infected persons remain at an increased risk of cancers related to infections with oncogenic viruses. Proposed pathogenic mechanisms of HIV-related cancers include decreased immune surveillance, decreased ability to suppress infection-related oncogenic processes and a state of chronic inflammation marked by alteration of the cytokine profile and expanded numbers of cytotoxic T lymphocytes with down-regulated co-stimulatory molecules and increased expression of markers of senescence in the setting of treated HIV infection. Here we discuss the cooperation of EBV-infected B cell- and environment-associated factors that may contribute to EBV-related lymphomagenesis in HIV-infected individuals. Environment-derived lymphomagenic factors include impaired host adaptive and innate immune surveillance, cytokine dysregulation and a pro-inflammatory state observed in the setting of chronic, cART-treated HIV infection. B cell factors include distinctive EBV latency patterns and host protein expression in HIV-associated LPD, as well as B cell-stimulating factors derived from HIV infection. We review the future directions for expanding therapeutic approaches in targeting the viral and immune components of EBV LPD pathogenesis.

Effect of Opioid Use on Immune Activation and HIV Persistence on ART

While there is an emerging consensus that engagement of the Mu opioid receptor by opioids may modulate various stages the HIV life cycle (e.g.: increasing cell susceptibility to infection, promoting viral transcription, and depressing immune responses to virally-infected cells), the overall effect on latency and viral reservoirs remains unclear. Importantly, the hypothesis that the increase in immune activation observed in chronic opioid users by direct or indirect mechanisms (i.e., microbial translocation) would lead to a larger HIV reservoir after ART-suppression has not been supported to date. The potential for a subsequent decrease in reservoirs after ART-suppression has been postulated and is supported by early reports of opioid users having lower latent HIV burden. Here, we review experimental data supporting the link between opioid use and HIV modulation, as well as the scientific premise for expecting differential changes in immune activation and HIV reservoir between different medications for opioid use disorder. A better understanding of potential changes in HIV reservoirs relative to the engagement of the Mu opioid receptor and ART-mediated immune reconstitution will help guide future cure-directed studies in persons living with HIV and opioid use disorder. Graphical Abstract Review. HIV replication, immune activation and dysbiosis: opioids may affect immune reconstitution outcomes despite viral suppression.

Associations between recent thymic emigrants and CD4+ T-cell recovery after short-term antiretroviral therapy initiation

Supplemental Digital Content is available in the text

Objective:

Around 20–30% of HIV-infected individuals (HIV+) on successful antiretroviral therapy (ART) fail to normalize their CD4⁺ T-cell counts. Various factors could contribute to the lack of immune reconstitution, one of them being thymic insufficiency. We aimed to explore associations between recent thymic emigrants (RTEs) and CD4⁺ T-cell recovery.

Design:

ART-naive HIV+ individuals who started ART with advanced AIDS were selected. Good versus poor immune reconstitution was defined by CD4⁺ gains above or below 100 CD4⁺ T cells/μl. The follow-up period was 6 months.

Methods:

Peripheral blood mononuclear cells were isolated and flow cytometry was used to characterize RTEs as the fraction of naive CD4⁺ T cells expressing CD31⁺, the platelet endothelial cell adhesion molecule. Markers of cellular activation, senescence, exhaustion and cycling were also assessed.

Results:

After 6 months on ART, HIV+ individuals with good immune reconstitution had higher absolute numbers of RTEs, compared with those with poor immune reconstitution, and these strongly correlated with CD4⁺ gains in those individuals with good immune reconstitution but not with poor immune reconstitution. We also found that CD8⁺ T-cell immune activation decreased as early as 2 months post-ART initiation in individuals with good immune reconstitution, but only at month 6 post-ART in individuals with poor immune reconstitution. Levels of immune activation were inversely correlated with the absolute numbers of RTEs in both groups, but more strongly so in individuals with poor immune reconstitution.

Conclusion:

We show that RTEs are linked to CD4⁺ T-cell recovery and that the degree of immune reconstitution is not directly linked to persistent immune activation.

Prevalence, incidence, predictors, treatment, and control of hypertension among HIV-positive adults on antiretroviral treatment in public sector treatment programs in South Africa

BACKGROUND

One of the key risk factors for cardiovascular disease is hypertension. Hypertension, which leads to heart attacks and strokes, already affects one billion people worldwide, making it a global public health issue. Incidence and prevalence of the condition is on the rise in low- and middle-income countries, with the biggest increase in sub-Saharan Africa and South Africa at the forefront. We examined the prevalence, incidence, predictors, treatment, and control of hypertension among HIV-positive patients on ART in a large South African observational cohort.

METHODS

We conducted a prospective study of ART naïve adults initiating ART at a public sector HIV clinic in South Africa between April 2004-2017. Patients with diagnosed hypertension at ART initiation were excluded from the incidence analysis. Log-binomial regression was used to estimate predictors of hypertension at ART initiation, while competing risks regression was used to evaluate the relationship between predictors of incident hypertension, accounting for death as a competing risk.

RESULTS

Among 77,696 eligible patients, 22.0% had prevalent hypertension at ART initiation. Of the remaining patients with no hypertension at ART initiation, 8,125 incident hypertension cases were diagnosed over the period of follow-up, corresponding to an incident rate of 5.4 per 100 person-years (95% confidence interval (CI): 5.3-5.6). We found patients ≥40 years of age and patients with a body mass index (BMI) ≥25kg/m2 were at increased risk of both prevalent and incident hypertension. Male patients and those with pre-hypertension at ART initiation had increased hazards of hypertension over the period of follow-up. When assessing the choice of antiretroviral drug in first-line ART, patients initiated on nevirapine were at 27% increased risk of developing hypertension compared to those initiated on efavirenz, while patients who initiated on either zidovudine or stavudine had a 40% increased risk of developing hypertension compared to patients initiated on tenofovir. Patientswith poorer health status at ART initiation (i.e. WHO III/IV stage, low CD4 count, low hemoglobin levels and low BMI) had a decrease risk of prevalent hypertension. We found an inverse relationship in patients with a CD4 count <50 cells/mm3 at ART initiation who had a 25% increased risk of incident hypertension compared to those with a CD4 count ≥350 cells/mm3.

CONCLUSION

Over 20% of patients in our cohort had hypertension at ART initiation, and 13% of those with normal blood pressure at ART initiation developed hypertension while on ART. Older patients, males, those on nevirapine, zidovudine or stavudine, and those who are overweight/obese should be targeted for frequent blood pressure monitoring and the identification of other cardiovascular risk factors to encourage lifestyle modifications. Additionally, these groups should be offered pharmaceutical therapy to help prevent myocardial infarction, heart failure, stroke, and kidney disease. Further research is needed to determine the level of access and adherence to pharmaceutical treatment for hypertension in this population. Additionally, an HIV-negative comparison population is needed to assess the association of the HIV virus itself with hypertension.

Distinct systemic microbiome and microbial translocation are associated with plasma level of anti-CD4 autoantibody in HIV infection

Microbial signals have been linked to autoantibody induction. Recently, we found that purified anti-CD4 autoantibodies from the plasma of chronic HIV-1-infected patients under viral-suppressed antiretroviral therapy (ART) play a pathologic role in poor CD4+ T cell recovery. The purpose of the study was to investigate the association of systemic microbiome and anti-CD4 autoantibody production in HIV. Plasma microbiome from 12 healthy controls and 22 HIV-infected subjects under viral-suppressed ART were analyzed by MiSeq sequencing. Plasma level of autoantibodies and microbial translocation (LPS, total bacterial 16S rDNA, soluble CD14, and LPS binding protein) were analyzed by ELISA, limulus amebocyte assay, and qPCR. We found that plasma level of anti-CD4 IgGs but not anti-CD8 IgGs was increased in HIV+ subjects compared to healthy controls. HIV+ subjects with plasma anti-CD4 IgG > 50 ng/mL (high) had reduced microbial diversity compared to HIV+ subjects with anti-CD4 IgG ≤ 50 ng/mL (low). Moreover, plasma anti-CD4 IgG level was associated with elevated microbial translocation and reduced microbial diversity in HIV+ subjects. The Alphaproteobacteria class was significantly enriched in HIV+ subjects with low anti-CD4 IgG compared to patients with high anti-CD4 IgG even after controlling for false discovery rate (FDR). The microbial components were different from the phylum to genus level in HIV+ subjects with high anti-CD4 IgGs compared to the other two groups, but these differences were not significant after controlling for FDR. These results suggest that systemic microbial translocation and microbiome may associate with anti-CD4 autoantibody production in ART-treated HIV disease.

The impact of HCV co-infection status on healthcare-related utilization among people living with HIV in British Columbia, Canada: a retrospective cohort study

Background

The burden of HCV among those living with HIV remains a major public health challenge. We aimed to characterize trends in healthcare-related visits (HRV) of people living with HIV (PLW-HIV) and those living with HIV and HCV (PLW-HIV/HCV), in British Columbia (BC), and to identify risk factors associated with the highest HRV rates over time.

Methods

Eligible individuals, recruited from the BC Seek and Treat for Optimal Prevention of HIV/AIDS population-based retrospective cohort (N = 3955), were ≥ 18 years old, first started combination antiretroviral therapy (ART) between 01/01/2000–31/12/2013, and were followed for ≥6 months until 31/12/2014. The main outcome was HRV rate. The main exposure was HIV/HCV co-infection status. We built a confounder non-linear mixed effects model, adjusting for several demographic and time-dependent factors.

Results

HRV rates have decreased since 2000 in both groups. The overall age-sex standardized HRV rate (per person-year) among PLW-HIV and PLW-HIV/HCV was 21.11 (95% CI 20.96–21.25) and 41.69 (95% CI 41.51–41.88), respectively. The excess in HRV in the co-infected group was associated with late presentation for ART, history of injection drug use, sub-optimal ART adherence and a higher number of comorbidities. The adjusted HRV rate ratio for PLW-HIV/HCV in comparison to PLW-HIV was 1.18 (95% CI 1.13–1.24).

Conclusions

Although HRV rates have decreased over time in both groups, PLW-HIV/HCV had 18% higher HRV than those only living with HIV. Our results highlight several modifiable risk factors that could be targeted as potential means to minimize the disease burden of this population and of the healthcare system.

Electronic supplementary material

The online version of this article (10.1186/s12913-018-3119-5) contains supplementary material, which is available to authorized users.

Impact of Human Immunodeficiency Virus Infection on Survival and Acute Toxicities From Chemoradiation Therapy for Cervical Cancer Patients in a Limited-Resource Setting

PURPOSE

To prospectively compare survival between human immunodeficiency virus (HIV)-infected versus HIV-uninfected cervical cancer patients who initiated curative chemoradiation therapy (CRT) in a limited-resource setting.

METHODS AND MATERIALS

Women with locally advanced cervical cancer with or without HIV infection initiating radical CRT in Botswana were enrolled in a prospective, observational, cohort study from July 2013 through January 2015.

RESULTS

Of 182 women treated for cervical cancer during the study period, 143 women initiating curative CRT were included in the study. Eighty-five percent of the participants (122 of 143) had stage II/III cervical cancer, and 67% (96 of 143) were HIV-infected. All HIV-infected patients were receiving antiretroviral therapy (ART) at the time of curative cervical cancer treatment initiation. We found no difference in toxicities between HIV-infected and HIV-uninfected women. The 2-year overall survival (OS) rates were 65% for HIV-infected women (95% confidence interval [CI] 54%-74%) and 66% for HIV-uninfected women (95% CI 49%-79%) (P = .70). Factors associated with better 2-year OS on multivariate analyses included baseline hemoglobin >10 g/dL (hazard ratio [HR] 0.37, 95% CI 0.19-0.72, P = .003), total radiation dose ≥75 Gy (HR 0.52, 95% CI 0.27-0.97, P = .04), and age <40 years versus 40-59 years (HR 2.17, 95% CI 1.05-4.47, P = .03).

CONCLUSIONS

Human immunodeficiency virus status had no effect on 2-year OS or on acute toxicities in women with well-managed HIV infection who initiated curative CRT in Botswana. In our cohort, we found that baseline hemoglobin levels, total radiation dose, and age were associated with survival, regardless of HIV status.

Aberrant plasma IL-7 and soluble IL-7 receptor levels indicate impaired T-cell response to IL-7 in human tuberculosis

T-cell proliferation and generation of protective memory during chronic infections depend on Interleukin-7 (IL-7) availability and receptivity. Regulation of IL-7 receptor (IL-7R) expression and signalling are key for IL-7-modulated T-cell functions. Aberrant expression of soluble (s) and membrane-associated (m) IL-7R molecules is associated with development of autoimmunity and immune failure in acquired immune deficiency syndrome (AIDS) patients. Here we investigated the role of IL-7/IL-7R on T-cell immunity in human tuberculosis. We performed two independent case-control studies comparing tuberculosis patients and healthy contacts. This was combined with follow-up examinations for a subgroup of tuberculosis patients under therapy and recovery. Blood plasma and T cells were characterised for IL-7/sIL-7R and mIL-7R expression, respectively. IL-7-dependent T-cell functions were determined by analysing STAT5 phosphorylation, antigen-specific cytokine release and by analysing markers of T-cell exhaustion and inflammation. Tuberculosis patients had lower soluble IL-7R (p < 0.001) and higher IL-7 (p < 0.001) plasma concentrations as compared to healthy contacts. Both markers were largely independent and aberrant expression normalised during therapy and recovery. Furthermore, tuberculosis patients had lower levels of mIL-7R in T cells caused by post-transcriptional mechanisms. Functional in vitro tests indicated diminished IL-7-induced STAT5 phosphorylation and impaired IL-7-promoted cytokine release of Mycobacterium tuberculosis-specific CD4⁺ T cells from tuberculosis patients. Finally, we determined T-cell exhaustion markers PD-1 and SOCS3 and detected increased SOCS3 expression during therapy. Only moderate correlation of PD-1 and SOCS3 with IL-7 expression was observed. We conclude that diminished soluble IL-7R and increased IL-7 plasma concentrations, as well as decreased membrane-associated IL-7R expression in T cells, reflect impaired T-cell sensitivity to IL-7 in tuberculosis patients. These findings show similarities to pathognomonic features of impaired T-cell functions and immune failure described in AIDS patients.

IL-7 is important for the development and homeostasis of T cells and promotes antigen-specific T-cell responses. Aberrant expression of plasma IL-7 and soluble IL-7R are found in autoimmune diseases and chronic viral infections. In AIDS patients—especially those who fail to reconstitute T-cell numbers during therapy—impaired IL-7-promoted T-cell functions indicated T-cell exhaustion/senescence. In order to evaluate the potential impact of IL-7 on tuberculosis, we characterised various parameters involved in the IL-7-response of tuberculosis patients and healthy contacts. Despite IL-7 being available at higher plasma levels among tuberculosis patients, the T-cell response to IL-7 was impaired when compared to healthy contacts. Soluble IL-7R levels were aberrantly low in plasma during acute tuberculosis but did not account for impaired IL-7 usage. Chronic inflammation in tuberculosis patients—reflected by increased IL-6 plasma levels—did not account for dysfunctional T-cell responses and analysed T-cell exhaustion markers were only moderately correlated. Our findings demonstrate that availability of IL-7 alone is not sufficient to promote protective T-cell immunity against tuberculosis. We describe aberrant IL-7/soluble IL-7R expression and impaired IL-7-mediated T-cell functions in tuberculosis patients with similarities and differences to described IL-7 dysregulation seen in patients with AIDS.

D-Dimer Levels and Traditional Risk Factors Are Associated With Incident Hypertension Among HIV-Infected Individuals Initiating Antiretroviral Therapy in Uganda

OBJECTIVES

We sought to describe blood pressure (BP) changes after antiretroviral therapy (ART) initiation and evaluate the association of markers of inflammation with incident hypertension in a cohort of HIV-infected individuals in Uganda.

METHODS

We used mixed effects linear regression to model changes in systolic BP over time among a cohort of HIV-infected individuals initiating ART in Uganda. After exclusion of participants with preexisting hypertension, we identified participants with normal BP throughout follow-up (controls) and those with elevated BP on ≥3 consecutive visits (cases). Before ART initiation, participants had testing for interleukin 6, kynurenine/tryptophan ratio, lipopolysaccharide, soluble CD14, soluble CD163, and D-dimer and those with viral suppression at 6 months during ART had repeat tests. We fit logistic regression models to estimate associations between biomarkers and risk of incident hypertension.

RESULTS

In the entire cohort, systolic BP increased by 9.6 mm Hg/yr (95% CI: 7.3 to 11.8) in the first 6 months of ART, then plateaued. Traditional factors: male gender (adjusted odds ratio (AOR) 2.76, 95% CI: 1.34 to 5.68), age (AOR 1.09, 95% CI: 1.04 to 1.13), overweight (AOR 4.48, 95% CI: 1.83 to 10.97), and a CD4 count <100 cells (AOR 3.08, 95% CI: 1.07 to 8.89) were associated with incident hypertension. After adjusting for these, D-dimer levels at month 6 were inversely associated with incident hypertension (AOR 0.61, 95% CI: 0.37 to 0.99). Although not significant, similar associations were seen with sCD14 and kynurenine/tryptophan ratio.

CONCLUSION

BP increases early after ART initiation in Ugandans. Traditional risk factors, rather than immune activation, were associated with incident hypertension in this population.

Plasma IP-10 Is Increased in Immunological NonResponders and Associated With Activated Regulatory T Cells and Persisting Low CD4 Counts

OBJECTIVE

To explore immune mechanisms and identify biomarkers associated with an inadequate immune recovery in patients with HIV with efficient antiretroviral therapy.

DESIGN

A cross-sectional study of 67 HIV-infected patients on antiretroviral therapy for ≥24 months with HIV RNA ≤20 copies per milliliter; 41 were defined as immunological nonresponders (INR) (CD4 < 400 cells per microliter) and 26 as immunological responders (CD4 > 600 cells per microliter). CD4 counts were also registered 2 years after inclusion.

METHODS

Cytokines, soluble markers of microbial translocation, and tryptophan catabolites were measured in plasma by multiplex assay, ELISA, or mass spectrometry. T-cell activation, differentiation, and regulatory T cells (Tregs) were analyzed by flow cytometry in 2 subgroups with comparable nadir CD4 counts.

RESULTS

Plasma interferon-inducible protein-10 (IP-10) levels were higher (P < 0.05), the T cells were more activated (CD38HLA-DR) (P < 0.05), the naive/effector memory T-cell ratio was lower (P < 0.01) and the proportion of resting Tregs (CD4CD45RAFoxP3) was reduced (P < 0.001) in INR patients compared with immunological responders. INR patients with CD4 counts ≤300 cells per microliter also demonstrated a higher fraction of activated Tregs (aTreg) (CD4CD147CD25) (P < 0.05). In the INR group, the aTreg percentages correlated with plasma IP-10 levels and inversely with CD4 counts (both P < 0.01). IP-10 levels (P < 0.05) and kynurenine/tryptophan ratio (P < 0.01) were negatively associated with the CD4 count 2 years after inclusion.

CONCLUSION

Patients with HIV with inadequate CD4 responses had higher levels of IP-10, more activated and differentiated T-cell phenotypes, as well as aTreg, compared with patients with satisfactory CD4 gain. High IP-10 levels were also associated with lower CD4 counts after 2 years.

Impaired Upregulation of the Costimulatory Molecules, CD27 and CD28, on CD4+ T Cells from HIV Patients Receiving ART Is Associated with Poor Proliferative Responses

HIV patients beginning antiretroviral therapy (ART) with advanced immunodeficiency often retain low CD4⁺ T cell counts despite virological control. We examined proliferative responses and upregulation of costimulatory molecules, following anti-CD3 stimulation, in HIV patients with persistent CD4⁺ T cell deficiency on ART. Aviremic HIV patients with nadir CD4⁺ T cell counts <100 cells/μL and who had received ART for a median time of 7 (range 1-11) years were categorized into those achieving low (<350 cells/μL; n = 13) or normal (>500 cells/μL; n = 20) CD4⁺ T cell counts. Ten healthy controls were also recruited. CD4⁺ T cell proliferation (Ki67) and upregulation of costimulatory molecules (CD27 and CD28) after anti-CD3 stimulation were assessed by flow cytometry. Results were related to proportions of CD4⁺ T cells expressing markers of T cell senescence (CD57), activation (HLA-DR), and apoptotic potential (Fas). Expression of CD27 and/or CD28 on uncultured CD4⁺ T cells was similar in patients with normal CD4⁺ T cell counts and healthy controls, but lower in patients with low CD4⁺ T cell counts. Proportions of CD4⁺ T cells expressing CD27 and/or CD28 correlated inversely with CD4⁺ T cell expression of CD57, HLA-DR, and Fas. After anti-CD3 stimulation, induction of CD27^hiCD28^hi expression was independent of CD4⁺ T cell counts, but lower in HIV patients than in healthy controls. Induction of CD27^hiCD28^hi expression correlated with induction of Ki67 expression in total, naïve, and CD31⁺ naïve CD4⁺ T cells from patients. In HIV patients responding to ART, impaired induction of CD27 and CD28 on CD4⁺ T cells after stimulation with anti-CD3 is associated with poor proliferative responses as well as greater CD4⁺ T cell activation and immunosenescence.

Naive and Memory CD4⁺ T Cells Are Differentially Affected in Indonesian HIV Patients Responding to ART

While most HIV patients beginning antiretroviral therapy (ART) with advanced immunodeficiency recover CD4(+) T cell numbers, the profiles and functions of the newly acquired CD4(+) T cells have not been monitored in a resource-limiting setting. In this study, HIV patients (n = 31) from Jakarta, Indonesia, were studied 9 months after commencing ART with nadir CD4(+) T cell counts <200 cells/μL. All patients were hepatitis C virus (HCV) seropositive, but asymptomatic. Twelve healthy age-matched controls from the same community were included. CD4(+) T cell subsets, immune activation (HLA-DR), and expression of the interleukin (IL)-7 receptor α chain (CD127) were quantitated by flow cytometry. Proliferation (expression of Ki67) was measured following in vitro stimulation (5 days) with anti-CD3 antibody or IL-7. Fifty-two percent of patients recovered CD4(+) T cell counts >200 cells/μL over 12 months. At 9 months, patients had fewer naive and CD31(+)-naive CD4(+) T cells, more effector memory (EM) CD4(+) T cells, and higher HLA-DR expression on CD4(+) T cells than controls. CD127 expression was low on all CD4(+) T cell subsets except for naive cells, where it was similar to controls. Similarly, after anti-CD3 antibody or IL-7 stimulation, patients had lower Ki67 expression than controls in all subsets, except naive CD4(+) T cells where it was normal or elevated. Overall in the first year of ART, patients had fewer naive and more EM CD4(+) T cells. Ongoing immune activation and, antigen-driven stimulation and differentiation of naive T cells may reduce the naive T cell pool, while driving the maturation and accumulation of memory cells with proliferative defects.

Quantifying Adaptive and Innate Immune Responses in HIV-Infected Participants Using a Novel High Throughput Assay

Objectives

HIV infection is characterised by persistent immune dysfunction of both the adaptive and innate immune responses. The aim of this study was to evaluate these responses using a novel high throughput assay in healthy controls and HIV-infected individuals prior to and following anti-retroviral treatment (ART).

Design

Cross-sectional study.

Methods

Whole blood was assessed using the QuantiFERON Monitor^® (QFM) assay containing adaptive and innate immunostimulants. Interferon (IFN)-γ levels (IU/mL) were measured by enzyme-linked immunosorbent assay (ELISA).

Results

We recruited HIV-infected participants (n = 20 off ART and viremic; n = 59 on suppressive ART) and HIV-uninfected controls (n = 229). Median IFN-γ production was significantly higher in HIV-infected participants compared to controls (IFN-γ 512 vs 223 IU/ml, p<0.0001), but within the HIV-infected participants there was no difference between those on or off ART (median IFN-γ 512 vs 593 IU/ml p = 0.94). Amongst the HIV-infected participants, IFN-γ production was higher in individuals with CD4 count>350 compared to <350 cells/μL (IFN-γ IU/ml 561 vs 259 p = 0.02) and in males compared to females (IFN-γ 542 vs 77 IU/ml p = 0.04). There were no associations between IFN-γ production and age, plasma HIV RNA, nadir CD4 count or duration of HIV infection. Using a multivariable analysis, neither CD4 nor sex were independently predictive of IFN-γ production.

Conclusion

Using a high throughput assay which assesses both adaptive and innate immune function, we showed elevated IFN-γ production in HIV-infected patients both on and off ART. Further research is warranted to determine if changes in QuantiFERON Monitor^® are associated with clinical outcomes.

Increased Immune Activation and Exhaustion in HIV-infected Youth

BACKGROUND

Immune activation and exhaustion drive several comorbidities and disease progression in HIV-infected adults; however, they are not well studied in HIV-infected youth. Thus, this study sought to examine levels of immune activation and exhaustion in this population, investigate associated HIV- and non-HIV-related variables and compare results with a matched healthy control group.

METHODS

HIV-infected youth 8-25 years of age on stable antiretroviral therapy with an HIV-1 RNA level <1000 copies/mL were enrolled, along with matched healthy controls. We measured T-cell and monocyte immune activation and exhaustion markers in cryopreserved peripheral blood mononuclear cell and plasma samples.

RESULTS

A total of 136 subjects (80 HIV+: 66% male; 91% black) were enrolled. Markers of CD4+ and CD8+ T-cell activation were higher in the HIV-infected group versus controls [mean % CD4+CD38+HLA-DR+ and CD8+CD38+HLA-DR+ = 2.2 versus 1.5 (P=0.002) and 4.9 versus 2.2 (P<0.0001), respectively], as were exhausted CD4+ and CD8+ T-cells [mean % CD4+CD38+HLA-DR+PD-1+ and CD8+CD38+HLA-DR+PD-1+ = 1.0 versus 0.5 (P<0.0001) and 1.6 versus 0.7 (P<0.0001), respectively]. There were no differences in proportions of inflammatory or patrolling monocytes between groups (P>0.05); however, soluble CD14 was higher in HIV-infected compared with controls (1.6 versus 1.4 µg/mL; P=0.01). Current CD4 count, low-density lipoprotein cholesterol and age were the variables most associated with CD4+ and CD8+ T-cell activation.

CONCLUSIONS

CD4+ and CD8+ T-cell immune activation and exhaustion are higher in HIV-infected youth compared with matched controls, while monocyte subpopulations are not altered despite a high soluble CD14 level. The clinical significance of the increased immune activation and exhaustion should be further explored.

Inflammation Perturbs the IL-7 Axis, Promoting Senescence and Exhaustion that Broadly Characterize Immune Failure in Treated HIV Infection

BACKGROUND

HIV-infected patients who fail to normalize CD4 T cells despite suppressive antiretroviral therapy have impaired immune homeostasis: diminished naive T-cell numbers, elevated T-cell turnover, senescence, and inflammation.

METHODS

Blood samples from immune failures (n = 60), immune successes (n = 20), and healthy controls (n = 20) were examined for plasma interleukin (IL)-7 levels, for cellular expression of the IL-7Rα chain (CD127), for the exhaustion and senescence markers programed death 1 (PD-1) and CD57, and for the survival factor Bcl2. Because both inflammatory and homeostatic cytokines can induce T-cell cycling, we also examined the effects of these mediators on exhaustion and senescence markers.

RESULTS

Plasma levels of IL-7 were elevated and both CD4 and CD8 T-cell CD127 expression was decreased in immune failure. Plasma levels of IL-7 correlated directly with naive CD4 T-cell counts in immune success and inversely with T-cell cycling (Ki67) in healthy controls and immune success, but not in immune failure. CD4 T-cell density of PD-1 was increased and Bcl2+ CD4 T cells were decreased in immune failure but not in immune success, whereas the proportion of T cells expressing CD57 was increased in immune failure. PD-1 and CD57 were induced on CD4 but not CD8 T cells by stimulation in vitro with inflammatory IL-1β or homeostatic (IL-7) cytokines.

CONCLUSIONS

Perturbation of the IL-7/IL-7 receptor axis, increased T-cell turnover, and increased senescence may reflect dysregulated responses to both homeostatic and inflammatory cytokines in immune failure patients.

CD38 Expression in a Subset of Memory T Cells Is Independent of Cell Cycling as a Correlate of HIV Disease Progression

In order to determine if the expression of the activation marker CD38 can correlate with HIV disease progression independently of cycling, we performed a cluster-based multivariate correlation analysis of total circulating CD4⁺ T cell counts and viral loads with frequencies of CD38 and Ki67 expression on CD4⁺ lymphocytes from patients with untreated HIV infection, stratified in maturation subpopulations, and subpopulation subsets defined by the expression of CXCR5, CXCR3, and CCR4. The frequencies of the activated phenotypes %CD38⁺ Ki67⁻ and %CD38⁺ Ki67⁺ of the CXCR5⁻ CXCR3⁻ CCR4⁺ (“pre-Th2”) central memory (T_CM) cell subset clustered together, comprising a significant negative correlate of total circulating CD4⁺ T cell counts and a positive correlate of viral load in multivariate analysis. Frequency of cycling-uncoupled CD38 expression in “pre-Th2” T_CM cells was a negative correlate of total circulating CD4⁺ T cell counts in univariate analysis, which was not the case of their %CD38⁺ Ki67⁺. CXCR5⁺ CXCR3⁻ CCR4⁻T_CM cells were underrepresented in patients, and their absolute counts correlated negatively with their %CD38⁺ Ki67⁻ but not with their % CD38⁺ Ki67⁺. Our results may imply that CD38 expression either reflects or participates in pathogenic mechanisms of HIV disease independently of cell cycling.

High-risk oncogenic HPV genotype infection associates with increased immune activation and T cell exhaustion in ART-suppressed HIV-1-infected women

Persistence of human papillomavirus (HPV) and cervical disease in the context of HIV co-infection can be influenced by introduction of antiretroviral therapy (ART) and sustained immune activation despite ART. We conducted a cross-sectional study in order to evaluate immune activation/exhaustion in ART-suppressed HIV(+) women with or without high-risk (HR) HPV-related cervical intraepithelial neoplasia (CIN). 55 South African women were recruited in three groups: HR (-) (n = 16) and HR (+) (n = 15) HPV with negative cervical histopathology, and HR (+) HPV with CIN grade 1/2/3 (n = 24). Sampling included endocervical brushing (HPV DNA genotyping), Pap smear (cytology), colposcopic punch biopsy (histopathology, histochemical evaluation of immune cells), and peripheral blood (clinical assessment, flow cytometry-based immune subset characterization). Statistics were done using R2.5.1. Irrespective of the presence of CIN, HR (+) HPV women had higher circulating levels of T cells expressing markers of activation/exhaustion (CD38, PD1, CTLA-4, BTLA, CD160), Tregs, and myeloid subsets expressing corresponding ligands (PDL1, PDL2, CD86, CD40, HVEM) than HR (-) HPV women. A decrease in circulating NK cells was associated with CIN grade. CD4(+) T cell count associated negatively with T cell exhaustion and expression of negative regulators on myeloid cells. Women with CIN when compared to HR (-) HPV women, had higher cervical cell density in stroma and epithelium for CD4(+), CD68(+), and CD11c(+) cells, and only in stroma for CD8(+) cells. We conclude that in ART-suppressed HIV-infected women with HPV co-infection the levels of T and myeloid cell activation/exhaustion are associated with the presence of HR HPV genotypes.

Normal T-cell activation in elite controllers with preserved CD4+ T-cell counts

BACKGROUND

HIV elite controllers suppress HIV viremia without antiretroviral therapy (ART), yet previous studies demonstrated that elite controllers maintain an activated T-cell phenotype. Chronic immune activation has detrimental consequences and thus ART has been advocated for all elite controllers. However, elite controllers are not a clinically homogenous group. Since CD4% is among the best predictors of AIDS-related events, in the current study, we assessed whether this marker can be used to stratify elite controllers needing ART.

METHODS

Sixteen elite controllers were divided into two groups based on CD4% (EC > 40% and EC ≤40%), and T-cell subsets were analyzed for markers of memory/differentiation (CD45RA, CCR7, CD28), activation (CD38/HLA-DR), immunosenescence (CD57), costimulation (CD73, CD28) and exhaustion (PD-1, CD160, Tim-3). Monocyte subsets (CD14, CD16) were also analyzed and sCD14 levels were quantified using ELISA.

RESULTS

In the EC group, expression of activation, exhaustion, and immunosensescence markers on T cells were significantly reduced compared with the EC group and similar to the seronegative controls. The EC group expressed higher levels of costimulatory molecules CD28 and CD73 and had lower levels of monocyte activation (HLA-DR expression) with a reduced frequency of inflammatory monocyte (CD14 CD16) subset. Furthermore, the EC group maintained a stable CD4% during a median follow-up of 6 years.

CONCLUSION

Elite controllers with preserved CD4T cells (EC) have normal T-cell and monocyte phenotypes and therefore may have limited benefit from ART. CD4% can be an important marker for evaluating future studies aimed at determining the need for ART in this group of individuals.

Increased ex vivo cell death of central memory CD4 T cells in treated HIV infected individuals with unsatisfactory immune recovery

Background

High levels of ex vivo CD4 T-cell death and the accumulation of highly differentiated and/or immunosenescent T cells have been associated with poor CD4 T-cell recovery in treated HIV-infected individuals. However, the relationship between cell death and T-cell differentiation is still unclear.

Methods

We have analyzed cell death, immunosenescence and differentiation parameters in HAART-treated subjects (VL <50 copies/mL for more than 2 years) with CD4 T-cell count <350 cells/μL (immunodiscordant, n = 23) or >400 cells/μL (immunoconcordant, n = 33). We included 11 healthy individuals as reference.

Results

As expected, suboptimal CD4 T-cell recovery was associated with low frequencies of naïve cells, high frequencies of transitional and effector memory cells and a subsequent low ratio of central/transitional memory cells in the CD4 compartment. These alterations correlated with spontaneous CD4 T-cell death. A deeper analysis of cell death in CD4 T-cell subsets showed increased cell death in memory cells of immunodiscordant individuals, mainly affecting central memory cells. Immunosenescence was also higher in immunodiscordant individuals albeit unrelated to cell death. The CD8 compartment was similar in both HIV-infected groups, except for an underrepresentation of naïve cells in immunodiscordant individuals.

Conclusion

Immunodiscordant individuals show alterations in memory CD4 T-cell differentiation associated with a short ex vivo lifespan of central memory cells and an in vivo low central/transitional memory cell ratio. These alterations may contribute to poor CD4 T-cell repopulation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0601-2) contains supplementary material, which is available to authorized users.

Increased T-cell turnover is associated with spondyloarthritis in virally suppressed patients with HIV-1 infection

OBJECTIVES

Spondyloarthritis (SpA) is one of the most frequently observed inflammatory joint diseases in HIV-1-seropositive patients. T-cells were described frequently as one of the major driving forces in SpA, therefore we tried to look for T-cell aberrancies in our HIV-positive patients with SpA.

METHODS

A total of 1098 files for HIV-positive patients who attended the HIV out-patient clinic of the Department of Clinical Immunology and Rheumatology at the Medical University Hanover for at least one visit between January 2004 and December 2010 were screened for the presence of a diagnosis of SpA. A cross-sectional study was conducted to investigate aberrancies in T-cell homeostasis induced by HIV-1 in these subjects.

RESULTS

The prevalence of SpA in the HIV-positive patients was 1.6% (18 of 1098). Interestingly, the percentage of patients with SpA who were human leucocyte antigen (HLA)-B27 negative in our HIV-positive cohort was 80%. Despite combination antiretroviral therapy (cART) and viral suppression, an incomplete immune recovery of T-cell naïve/memory distribution and turnover, as identified by intracellular Ki-67 expression, was observed in HIV-positive patients with SpA.

CONCLUSIONS

Independent of HLA-B27 status and despite cART, HIV-positive patients can develop SpA and exhibit an increased T-cell turnover rate.

Interleukin-7 signalling defects in naive CD4+ T cells of HIV patients with CD4+ T-cell deficiency on antiretroviral therapy are associated with T-cell activation and senescence

OBJECTIVE

To examine the relationship of defects in interleukin (IL)-7-induced naive CD4 T-cell homeostasis with residual immune activation and CD4 T-cell senescence in HIV patients receiving antiretroviral therapy (ART) who exhibit persistent CD4 T-cell deficiency.

DESIGN

IL-7 induced proliferation of, and IL-7 receptor signalling in, total and naive CD4 T cells of HIV patients who had low (<350 cells/μl) or normal (>500 cells/μl) CD4 T-cell counts on ART was examined and related to markers of CD4 T-cell activation and senescence and innate immune activation.

METHODS

Total, naive (CD45RA CD27) and CD31 naive CD4 T cells from aviremic HIV patients (n=39) with nadir CD4 T-cell counts less than 100 cells/μl, who had received ART for a median time of 7 (range 1-11) years, were assessed for CD127 expression, proliferation (Ki67), signal transducer and activator of transcription 5 phosphorylation (pSTAT5) and CD127 modulation following IL-7 stimulation. Changes were related to proportions of CD4 T cells expressing HLA-DR or CD57 and plasma levels of sCD14, CXCL9 and CXCL10.

RESULTS

Patients with CD4 T-cell deficiency exhibited lower expression of CD127 on total, naive and CD31 naive CD4 T cells. Downregulation of CD127 after culture with IL-7 correlated inversely with CD4 T-cell counts and directly with Ki67 expression. Induction of pSTAT5 in CD4 T-cell subsets was greater in patients with normal CD4 T-cell counts. CD127 expression correlated inversely with proportions of CD4CD57 T cells, and pSTAT5 induction correlated inversely with CD4 T-cell expression of HLA-DR and CD57.

CONCLUSION

Defects of IL-7 signalling in HIV patients with persistent CD4 T-cell deficiency receiving ART are associated with CD4 T-cell activation and senescence.

Correlation between different methods to measure microbial translocation and its association with immune activation in long-term suppressed HIV-1-infected individuals

INTRODUCTION

Microbial translocation (MT) has been proposed as one of the triggering mechanisms of persistent immune activation associated to HIV-1 infection. Our objectives were to determine the correlation between different measurements of MT in suppressed HIV-1-infected individuals and to evaluate its correlation with immune activation.

METHODS

Eighteen suppressed HIV-1-infected patients with CD4+ T-cell count above 350 cells per cubic millimeter and undetectable plasma viral load, included in antiretroviral treatment intensification clinical trials, were evaluated. Samples obtained at baseline and at established time points during the trials were analyzed. Lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP), soluble CD14 (sCD14), and bacterial 16S ribosomal DNA (16S rDNA), and markers of immune activation were determined.

RESULTS

We analyzed 126 plasma samples from the 18 patients. LPS significantly correlated with sCD14 (P < 0.001, r = 0.407) and LBP (P = 0.042, r = 0.260). Also, a significant correlation was found between sCD14 and LBP (P = 0.009, r = 0.325) but not between bacterial 16S rDNA and LPS, sCD14, or LBP (P = 0.346, P = 0.405, and P = 0.644). On the other hand, no significant correlation was found between LPS, sCD14, or LBP and CD4 (P = 0.418, P = 0.619, and P = 0.728) or CD8 T-cell activation (P = 0.352, P = 0.275, and P = 0.124). Bacterial 16S rDNA correlated with activated CD4 T cells (P = 0.005, r = 0.104) but not with activated CD8 T cells (P = 0.171).

CONCLUSIONS

There is a good correlation in the quantification of LPS, sCD14, and LBP levels, but not with bacterial 16S rDNA, as measurements of MT. We are unable to ensure that MT directly triggers T-cell immune activation at least among these patients with relatively good immune recovery and under treatment intensification.

Low nadir CD4 cell count predicts sustained hypertension in HIV-infected individuals

Hypertension is associated with cardiovascular disease in the human immunodeficiency virus (HIV)-infected population. The authors aimed to test the hypothesis whether advanced immunosuppression with low nadir CD4 lymphocyte cell count is a predictor of sustained hypertension in HIV-infected individuals. In a longitudinal study of an HIV cohort of 434 patients (43±11 years, 72% men, 71% Caucasians), standardized blood pressure was measured in duplicate during 3 clinical visits both at baseline and after 3.4±0.8 years. The lowest CD4 cell count in the individual history was recorded as nadir CD4. Both nadir CD4 cell count<50 cells/μL and duration of antiretroviral therapy (ART) were associated with sustained hypertension, and the highest proportion of hypertensive patients was observed in those who had both nadir CD4 cell count<50 cells/μL and prolonged ART duration. Nadir CD4 cell-count<50 cells/μL was an independent predictor of hypertension (adjusted odds ratio [OR], 2.48; 95% confidence interval [CI], 1.27-4.83), as was ART duration (adjusted OR, 1.13; 95% CI, 1.03-1.24). The predictive power of ART duration was more pronounced in patients with nadir CD4 cell count<50 cells/μL. Delaying ART initiation until a state of advanced immunosuppression might add to and even fuel the cardiovascular risk associated with ART.

Immunosenescence and HIV

PURPOSE OF REVIEW

The present review discusses the interplay between HIV infection and other environmental factors (e.g. co-infection with CMV) in the acceleration of the aging process of the immune system, leading to 'immunosenescence.'

RECENT FINDINGS

Basic studies in cell biology demonstrate that replicative senescence is a common pathway of many cell lineages, including those of the immune system, characterized by activation of a unique pro-inflammatory secretory program. In the setting of HIV disease, this process is accelerated, resulting in an immunosuppressed state that diminishes the ability of the immune system to contain virus while at the same time facilitating viral replication and spread. Clinically, these changes result in a lower capacity to respond to new infections as well as an increased frequency of age-associated end-organ disease (e.g. cardiovascular complications, cancer, and neurologic disease).

SUMMARY

Accelerated immunosenescence in the setting of HIV disease is associated with increased morbidity and mortality, prompting the need for more investigation into its causes, diagnosis, and treatment.

Immunologic failure despite suppressive antiretroviral therapy is related to activation and turnover of memory CD4 cells

BACKGROUND

Failure to normalize CD4(+) T-cell numbers despite effective antiretroviral therapy is an important problem in human immunodeficiency virus (HIV) infection.

METHODS

To evaluate potential determinants of immune failure in this setting, we performed a comprehensive immunophenotypic characterization of patients with immune failure despite HIV suppression, persons who experienced CD4(+) T-cell restoration with therapy, and healthy controls.

RESULTS

Profound depletion of all CD4(+) T-cell maturation subsets and depletion of naive CD8(+) T cells was found in immune failure, implying failure of T-cell production/expansion. In immune failure, both CD4(+) and CD8(+) cells were activated but only memory CD4(+) cells were cycling at increased frequency. This may be the consequence of inflammation induced by in vivo exposure to microbial products, as soluble levels of the endotoxin receptor CD14(+) and interleukin 6 were elevated in immune failure. In multivariate analyses, naive T-cell depletion, phenotypic activation (CD38(+) and HLA-DR expression), cycling of memory CD4(+) T cells, and levels of soluble CD14 (sCD14) distinguished immune failure from immune success, even when adjusted for CD4(+) T-cell nadir, age at treatment initiation, and other clinical indices.

CONCLUSIONS

Immune activation that appears related to exposure to microbial elements distinguishes immune failure from immune success in treated HIV infection.

CD4+ T-cell deficiency in HIV patients responding to antiretroviral therapy is associated with increased expression of interferon-stimulated genes in CD4+ T cells

Most patients with human immunodeficiency virus (HIV) who remain CD4(+) T-cell deficient on antiretroviral therapy (ART) exhibit marked immune activation. As CD4(+) T-cell activation may be mediated by microbial translocation or interferon-alpha (IFN-α), we examined these factors in HIV patients with good or poor CD4(+) T-cell recovery on long-term ART. Messenger RNA levels for 3 interferon-stimulated genes were increased in CD4(+) T cells of patients with poor CD4(+) T-cell recovery, whereas levels in patients with good recovery did not differ from those in healthy controls. Poor CD4(+) T-cell recovery was also associated with CD4(+) T-cell expression of markers of activation, senescence, and apoptosis, and with increased serum levels of the lipopolysaccharide receptor and soluble CD14, but these were not significantly correlated with expression of the interferon-stimulated genes. Therefore, CD4(+) T-cell recovery may be adversely affected by the effects of IFN-α, which may be amenable to therapeutic intervention.

Intensification of antiretroviral therapy with raltegravir or addition of hyperimmune bovine colostrum in HIV-infected patients with suboptimal CD4+ T-cell response: a randomized controlled trial

BACKGROUND

Despite virally suppressive combination antiretroviral therapy (cART), some HIV-infected patients exhibit suboptimal CD4(+) T-cell recovery. This study aimed to determine the effect of intensification of cART with raltegravir or addition of hyperimmune bovine colostrum (HIBC) on CD4(+) T-cell count in such patients.

METHODS

We randomized 75 patients to 4 treatment groups to receive raltegravir, HIBC, placebo, or both raltegravir and HIBC in a factorial, double-blind study. The primary endpoint was time-weighted mean change in CD4(+) T-cell count from baseline to week 24. T-cell activation (CD38(+) and HLA-DR(+)), plasma markers of microbial translocation (lipopolysaccharide, 16S rDNA), monocyte activation (soluble (s) CD14), and HIV-RNA (lowest level of detection 4 copies/mL) were monitored. Analysis was performed using linear regression methods.

RESULTS

Compared with placebo, the addition of neither raltegravir nor HIBC to cART for 24 weeks resulted in a significant change in CD4(+) T-cell count (mean difference, 95% confidence interval [CI]: 3.09 cells/μL, -14.27; 20.45, P = .724 and 9.43 cells/μL, -7.81; 26.68, P = .279, respectively, intention to treat). There was no significant interaction between HIBC and raltegravir (P = .275). No correlation was found between CD4(+) T-cell count and plasma lipopolysaccharide, 16S rDNA, sCD14, or HIV-RNA.

CONCLUSION

The determinants of poor CD4(+) T-cell recovery following cART require further investigation.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov identifier: NCT00772590, Australia New Zealand Clinical Trials Registry: ACTRN12609000575235.

Biomarkers of immune dysfunction following combination antiretroviral therapy for HIV infection

Combination antiretroviral therapy (cART) has significantly reduced morbidity and mortality of HIV-infected patients, yet their life expectancy remains reduced compared with the general population. Most HIV-infected patients receiving cART have some persistent immune dysfunction characterized by chronic immune activation and premature aging of the immune system. Here we review biomarkers of T-cell activation (CD69, -25 and -38, HLA-DR, and soluble CD26 and -30); generalized immune activation (C-reactive protein, IL-6 and D-dimer); microbial translocation (lipopolysaccharide, 16S rDNA, lipopolysaccharide-binding protein and soluble CD14); and immune dysfunction of specific cellular subsets (T cells, natural killer cells and monocytes) in HIV-infected patients on cART and their relationship to adverse clinical outcomes including impaired CD4 T-cell recovery, as well as non-AIDS clinical events, such as cardiovascular disease.

Robust interferon-α and IL-12 responses by dendritic cells are related to efficient CD4+ T-cell recovery in HIV patients on ART

Amongst HIV patients with successful virological responses to antiretroviral therapy (ART), poor CD4(+) T-cell recovery is associated with low nadir CD4(+) T-cell counts and persistent immune activation. These factors might be influenced by dendritic cell (DC) function. Interferon-α-producing plasmacytoid DC and IL-12-producing myeloid DC were quantified by flow cytometry after stimulation with agonists to TLR7/8 (CL075) or TLR9 (CpG-ODN). These were compared between patients who achieved CD4(+) T-cell counts above or below 200 cells/μL after 6 months on ART (High vs. Low groups). High Group patients had more DC producing interferon-α or IL-12 at Weeks 6 and 12 on ART than Low Group patients. The frequencies of cytokine-producing DC at Week 12 were directly correlated with CD4(+) T-cell counts at baseline and at Week 12. Patients with good recovery of CD4(+) T-cells had robust TLR-mediated interferon-α responses by plasmacytoid DC and IL-12 responses by myeloid DC during early ART (1-3 months).

Dissociation of CD154 and cytokine expression patterns in CD38+ CD4+ memory T cells in chronic HIV-1 infection

Expression of the activation antigen CD38 on T cells is a strong predictor of the risk of HIV disease progression, but it is not known whether CD38 is a marker or mediator of dysfunction. We examined the relationship between CD38 expression and responses to T-cell receptor stimulation in central memory and effector memory CD4 T cells in HIV-infected persons and in healthy controls. Basal CD38 expression was preserved by blocking golgi transport with brefeldin A. Intracellular expression of interleukin 2, interferon γ, and CD154 was measured after stimulating peripheral blood mononuclear cells with the superantigen staphylococcal enterotoxin B with or without anti-CD28 costimulation. Interferon-γ responses were comparable or increased in stimulated CD38 memory cells, and the interleukin 2 responses of costimulated CD38 central memory cells were decreased in HIV infection. In CD38 cells and especially in CD38 cells of HIV-infected persons, stimulated memory cells more often failed to express CD154 (CD40 ligand) when induced to express cytokine. A dissociated cytokine and CD154 expression by memory CD4 T cells may impair interactions between T cells and antigen-presenting cells, contribute to impaired immunity and help explain the relationship between CD38 expression and disease progression in chronic HIV infection.

HIV+ elite controllers have low HIV-specific T-cell activation yet maintain strong, polyfunctional T-cell responses

OBJECTIVE

HIV elite controllers are a unique group of rare individuals who maintain undetectable viral loads in the absence of antiretroviral therapy. We studied immune responses in these individuals to inform vaccine development, with the goal of identifying the immune correlates of protection from HIV.

METHODS

We compared markers of cellular activation, HIV-specific immune responses and regulatory T (Treg) cell frequencies in four groups of individuals: HIV-negative healthy controls, elite controllers (HIV RNA level <75 copies/ml), individuals on HAART and individuals with HIV RNA level more than 10,000 copies/ml (noncontrollers).

RESULTS

Elite controllers possessed significantly lower levels of activated HIV-specific CD8 T cells and of recently divided HIV-specific CD4 T cells than noncontrollers, whereas these differences were not seen in the respective cytomegalovirus-specific T-cell populations. Elite controllers also mounted a stronger and broader cytokine and chemokine response following HIV-specific stimulation than individuals on HAART and noncontrollers. Finally, we found that HAART-suppressed individuals had elevated Treg cell frequencies, whereas elite controllers and noncontrollers maintained normal percentages of Treg cells.

CONCLUSION

Elite controllers maintain high levels of HIV-specific immune responses with low levels of HIV-specific T-cell activation and do not have elevated Treg cell levels. Based on these data an ideal HIV vaccine would induce strong HIV-specific immune responses whereas minimizing HIV-specific T-cell activation.

Premature immunosenescence in HIV-infected patients on highly active antiretroviral therapy with low-level CD4 T cell repopulation

OBJECTIVES

To analyse the role of thymic function and its association with cellular immunosenescence markers in patients with low-level CD4 T cell repopulation, despite complete HIV RNA replication control on highly active antiretroviral therapy (HAART).

METHODS

Cellular immunosenescence markers comparing patients with CD4 T cell counts <or=250 cells/mm(3) for >or=48 weeks (n = 11) and patients with a CD4 T cell count >or=500 cells/mm(3) (n = 11) were investigated. Both groups were also compared with 11 healthy volunteers of similar age. Naive CD4 T cell counts, beta- and delta-T cell rearrangement excision circles, recent thymic emigrants, replicative senescence marker, cell activation, and rate of apoptosis were analysed. The Mann-Whitney U-test was used to compare parameters between both low-level and high-level CD4 T cell repopulation groups, and healthy volunteers.

RESULTS

Our results showed a lower thymic activity in patients with low-level CD4 T cell repopulation, leading to a decline in CD4 T cell production. On the other hand, a higher activation along with a higher replicative senescence of CD4 T cells contributed to a higher rate of apoptotic CD4 T cells in this group of patients.

CONCLUSIONS

We propose a model with several different related mechanisms involved in premature immune senescence in HIV-infected patients with low-level CD4 repopulation on HAART. The understanding of such different mechanisms could help find effective strategies to prevent immune decay.

Replication capacity in relation to immunologic and virologic outcomes in HIV-1-infected treatment-naive subjects

OBJECTIVES

To evaluate the association between baseline (BL) replication capacity (RC) (RCBL) and immunologic/virologic parameters (at BL and after 48 weeks on therapy) in HIV-1-infected subjects initiating antiretroviral therapy.

METHODS

RCBL was determined using a modified Monogram PhenoSense HIV drug susceptibility assay on plasma HIV-1 from 321 treatment-naive subjects from AIDS Clinical Trials Group 384. Univariate and multivariable analyses were performed to determine the association of RCBL with BL and on-therapy virologic and immunologic outcomes.

RESULTS

Higher RCBL was associated with lower baseline CD4 (CD4BL) (r = -0.23, P < 0.0001), higher baseline HIV-1 RNA (r = 0.25, P < 0.0001), higher CD4BL activation percent (r = 0.23, P < 0.0001), and lower CD4BL memory count (r = -0.21, P = 0.0002). In a multivariable model, week 48 CD4 increase (DeltaCD448) was associated with lower CD4BL memory count and higher CD4BL-naive percent (P = 0.004, P = 0.015, respectively). The interaction between CD4BL and RCBL was significant (P = 0.018), with a positive association between RCBL and DeltaCD448 in subjects with higher CD4BL and a negative association at lower absCD4BL.

CONCLUSIONS

At baseline, higher RC was significantly associated with higher HIV-1 RNA, higher CD4 cell activation, lower CD4 cell count, and lower CD4 memory cell count. These factors may interact, directly or indirectly, to modify the extent to which CD4 recovery occurs in patients starting antiretroviral therapy at different CD4BL counts.

HIV immunopathogenesis and strategies for intervention

Therapeutic options aimed at tackling the HIV pandemic face many obstacles. The lack of readily accessible and affordable therapies means that most of those affected go untreated. The array of escape mechanisms used by HIV has undermined the efficiency of many antiviral products and continually represents a barrier to the development of an effective vaccine. Recent developments have seen a shift away from a cytopathic viral model of HIV pathogenesis towards the crucial role of immunopathogenic features--notably generalised immune activation--in the development of AIDS. As conventional vaccine strategies have sought to promote viral neutralisation and suppressive cellular responses, novel strategies that aim to address HIV immunopathogenesis should be sought. We review current opinion on HIV-induced pathogenic immune activation and strategies aimed at eliminating HIV, including a potential role for non-neutralising antibodies as part of a therapeutic vaccine option.

Factors associated with poor immunologic responses despite viral suppression in markedly immunosuppressed patients

To determine the factors associated with poor immunologic responses despite viral suppression in markedly immunocompromised patients (</=200 CD4 cells per microliter at baseline), individuals with less than 100 CD4 increases after 12 months of nelfinavir-based highly active antiretroviral therapy (HAART; n = 114) were compared to those with 100 or more CD4 increases (n = 338). Responders were more likely to be naïve to antiretroviral therapy (p = 0.009) and to protease inhibitors (p< 0.001), less likely to have undetectable viral load at baseline (p = 0.01), to be infected through injection drug use (p = 0.02), to receive two versus three daily nelfinavir doses (p = 0.05), and to have higher viral load (p< 0.001) and lower CD4 counts (p = 0.03) at baseline than nonresponders. Logistic regression analysis revealed that baseline viral load (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.64-0.91), two daily nelfinavir doses (OR 1.85, 95% CI 1.12-3.03) and prior treatment with protease inhibitors (OR 1.85, 95% CI 1.11-3.07) were significantly predictive of poor immunologic responses. On the contrary, viral load had no predictive role in antiretroviral therapy (ART)-naïve patients (p = 0.7). We conclude that poor immunologic responses are common in these patients. Lower viral load at baseline is associated with poorer responses, which could be related to suboptimal prior antiretroviral therapy. In patients taking nelfinavir, administration in two versus three daily doses is also associated with worse immunologic responses.

Disorders of immune reconstitution in patients with HIV infection responding to antiretroviral therapy

Patients with HIV infection who were very immunodeficient before achieving a virologic response to antiretroviral therapy (ART) may experience various disorders of immune reconstitution. Immune restoration disease occurs in approximately 10% to 50% of patients and results from the restoration of a pathogen-specific immune response that causes immunopathology and presents as tissue inflammation or cellular proliferative disease. Opportunistic infections occur in no more than 5% of patients, but approximately one half of these patients have higher than expected CD4 T-cell counts and appear to have residual immune dysfunction. Autoimmune disease may arise because the reconstituted immune system confers an increased susceptibility to immune dysregulation but there may be different mechanisms because Graves' disease presents after a median time of about 2 years of ART whereas systemic lupus erythematosus presents earlier. Persistent CD4 T-cell deficiency (< 500/microL) affects up to 60% of patients and appears to reflect depletion of the naïve T-cell pool that results from low production and/or increased turnover of cells.