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

How to properly define immunological nonresponse to antiretroviral therapy in people living with HIV? an integrative review

In recent decades, significant progress has been made in understanding the mechanisms underlying human immunodeficiency virus (HIV) infection and its treatment. Antiretroviral therapy (ART) has notable improved the life expectancy and quality of life for people living with HIV (PLHIV) by suppressing viral replication and promoting CD4+ T-cell recovery. However, despite its efficacy, approximately 10-40% of ART-treated PLHIV with virological suppression (<50 RNA copies/mL) do not achieve adequate immunological reconstitution. These PLHIV, classified as immunological non-responders (INR), experience higher morbidity and mortality rates compared to those with satisfactory immune reconstitution, known as immunological responders (IR). Various studies have explored the mechanisms contributing to immunological nonresponse, yet a major challenge remains: the lack of a standardized definition of immunological response and nonresponse across studies. Currently, definitions are inconsistent, limiting comparability between studies. This review proposes a clear and adequate classification for IR and INR PLHIV to support future advancements in understanding immunological recovery and improving the quality of life for ART-treated PLHIV.

The influence of extrinsic apoptosis gene expression on immunological reconstitution of male ART-treated PLHIV

The primary goal of antiretroviral therapy (ART) is to suppress viral replication to undetectable levels (< 50 copies/mL). Despite achieving complete viral suppression, 10-40% of individuals on ART do not adequately restore their CD4 + T-cell count, being defined as immunological non-responders (INR). Factors such as sex, age at treatment initiation, coinfections, and pre-ART CD4 + T-cell count may influence this insufficient recovery. This impairment can also result from poor production or exacerbated destruction of CD4 + T-cells, particularly through extrinsic pathway-mediated apoptosis involving Fas/FasL and caspase-3. Thus, this study aimed to evaluate the expression profile of extrinsic apoptosis pathway genes (CASP3, FAS, FASLG) in adult male HIV patients on ART. The patients were stratified as immunological responders (n = 25) and immunological non-responders (n = 8) based on the increase and total count of CD4 + T-cells. Significant differences for CASP3 (FC = 1.39, p = 0.047) and FASLG (FC = 1.94, p < 0.0001) gene expressions were identified between IR and INR groups, but not for FAS (FC=-1.2, p = 0.638). This study indicates increased apoptotic pathway gene expression in INR and highlights the influence of cell destruction mechanisms on immunological recovery.

Insights to the HIV-associated visceral leishmaniasis clinical outcome: lessons learned about immune mediated disorders

Most cases of visceral leishmaniasis (VL) and human immunodeficiency virus (HIV) co-infection (VL/HIV) in the Americas occur in Brazil, and the prevalence of VL/HIV has been increasing since 2019, reaching 19% in 2023. This association presents a challenge for the management of VL, since both VL and HIV infection share immunopathogenic characteristics that can reciprocally affect co-infected patients. Thus, VL may contribute to the immunosuppression and other immunological disturbances associated with the rapid progression to acquired immunodeficiency syndrome (AIDS), whereas HIV infection accelerates the development of active VL and reduces the probability of a successful response to anti-Leishmania therapy, resulting in an increase in the relapse and lethality rates of VL. In this synergistic impairment, one of the most critical hallmarks of VL/HIV co-infection is the enhancement of immunosuppression and intense chronic immune activation, caused not only by each infection per se, but also by the cytokine storm and translocation of microbial products. Thus, co-infected patients present with an impaired effector immune response that may result in inefficient parasitic control. In addition, the chronic activation environment in VL/HIV patients may favor progression to early immunosenescence and exhaustion, worsening the patients' clinical condition and increasing the frequency of disease relapse. Herein, we review the immunological parameters associated with the immunopathogenesis of VL/HIV co-infection that could serve as good biomarkers of clinical prognosis in terms of relapse and severity of VL.

One-Year Frailty Transitions Among Persons With HIV Aged 70 Years or Older on Antiretroviral Treatment

Background

People with HIV (PWH) are aging. Frailty is an age-related condition predictive of hospitalization and mortality. Here, we assessed the frequency and factors associated with frailty transitions at 1-year follow-up in elderly PWH.

Methods

Five hundred eight PWH aged 70 years or older who were on antiretroviral treatment were included in the French multicenter SEPTAVIH study in 2019-2020. Participants were classified as robust, prefrail, or frail according to Fried frailty phenotype at baseline and at 1 year. Logistic regression models were used to evaluate socioeconomic and medical factors associated with transition between frailty states. Models were adjusted for gender, age at baseline, education, and period of HIV diagnosis (before vs after 1996).

Results

Seventeen PWH died during the 1-year follow-up. Of the remaining 491 PWH (median age, 73 years), frailty status worsened for 18% of participants and improved for 14% at 1 year. Advanced age, baseline CD4+ T-cell count <350 cells/mm3, and type 2 diabetes were associated with transition from prefrailty to frailty (adjusted odds ratio [aOR], 1.10 per 1-year positive difference; 95% CI, 1.01-1.20; aOR, 3.05; 95% CI, 1.14-8.18; and aOR, 2.63; 95% CI, 1.05-6.57; respectively). Being female was associated with more frequent improvement from prefrailty to robustness (aOR, 2.50; 95% CI, 1.09-5.55).

Conclusions

Preventing frailty in elderly PWH is a long-term problem, beginning with the early diagnosis of HIV infection and the management of comorbidities.

Unexpected CD4 decay, hidden adherence gaps, resilience, and the need for long-acting therapy in a single HIV outpatients' cohort

This single-centre, single-cohort study examines hidden non-adherence to antiretroviral therapy in a setting of persistent optimal viral suppression but concordant absolute and percent CD4 decay by >10% from the previous test. After the finding of important drug holidays in two virologically suppressed patients, between January 2021 and January 2022 all PLWH who fulfilled CD4 decay criteria were asked for how long therapy was interrupted, how many days before re-testing CD4 and HIV RNA was it resumed and the reason for interruption. Of 668 HIV-infected subjects, 61 fulfilled the pre-specified criteria for significant CD4 decay and 15 (2.25% of the total, 25% of the CD4 decay group) admitted long-lasting treatment interruptions, compensated by treatment resumption before the subsequent testing. Eleven treatment interruptions exceeded 28 days, and none was shorter than 15 days. CD4 recovery was worse at 6 months in non-adherent subjects (-0.5 vs + 16/mmc, p < 0.0001) and in non adherence vs immune decay time-related with COVID-19 (0 vs + 22/mmc, p < 0.0001). Reasons for interrupting treatment were travel, psychological, poverty-related, addiction and sentimental sphere problems. Long-acting regimens, with stringent control of precision in timely administration, may protect PLWH from damaging their health status and possibly transmit HIV.

HIV-Induced Thymic Insufficiency and Aging-Related Immunosenescence on Immune Reconstitution in ART-Treated Patients

The mechanisms underlying unsatisfactory immune reconstitution in HIV-1 positive patients under ART have not been fully elucidated, even after years of investigation. Thus, this study aimed to assess the correlation between age and thymic production profile, and its influence on inadequate immunological recovery. Here, 44 ART-treated patients with undetectable plasma HIV-1 load (<40 copies/mL) were classified as 31 immunological responders (IR) and 13 immunological non-responders (INR), according to their CD4+ T-cell count after 18 months of ART. The thymic function was assessed by identifying recent thymic emigrants (RTEs) CD4+ T cells (CD4+/CD45RA+CD31+) in PBMCs using flow cytometry. Clinical data were also analyzed from medical records. The INR group showed a higher age at ART initiation (41 ± 3.0) compared to the IR (33.7 ± 2.1) group (p = 0.041). Evaluating RTE CD4+ T-cells, we observed a lower percentage in the INR group (19.5 ± 6.3) compared to the IR group (29.9 ± 11.5) (p = 0.012). There was a strong negative correlation between age at ART initiation and RTE CD4+ T-cells in INRs (r = -0.784, p = 0.004). Our study has highlighted the thymic insufficiency and aging-related immunosenescence with unsatisfactory immunological recovery during ART in HIV-1 positive patients.

Cellular and molecular insights into incomplete immune recovery in HIV/AIDS patients

Highly active antiretroviral therapy (ART) can effectively inhibit virus replication and restore immune function in most people living with human immunodeficiency virus (HIV). However, an important proportion of patients fail to achieve a satisfactory increase in CD4⁺ T cell counts. This state is called incomplete immune reconstitution or immunological nonresponse (INR). Patients with INR have an increased risk of clinical progression and higher rates of mortality. Despite widespread attention to INR, the precise mechanisms remain unclear. In this review, we will discuss the alterations in the quantity and quality of CD4⁺ T as well as multiple immunocytes, changes in soluble molecules and cytokines, and their relationship with INR, aimed to provide cellular and molecular insights into incomplete immune reconstitution.

Accelerated Aging of T-cell Subsets among ART-Naïve HIV-Infected Chinese Men who Have Sex with Men: A Case-control Study

BACKGROUND

Evidence of lymphopoiesis, exhaustion, and premature aging in Chinese patients with human immunodeficiency virus (HIV) is very limited.

OBJECTIVE

To assess biological aging and immune senescence in Chinese healthy controls (HC) and ART-naïve HIV-infected men who have sex with men (MSM).

METHODS

This case-control study was conducted in Beijing Ditan Hospital from March 2018 to June 2019. The percentages of naïve (TN), central memory (TCM), effector memory (TEM), and terminally differentiated memory (TemRA) subsets of CD4 and CD8 T cells were studied, along with markers of senescence (CD28-CD57+) and activation (HLA-DR+). Telomere length of naïve (CD45RA+) and memory (CD45RO+) CD8 T cells was quantified by real-time PCR.

RESULTS

A total of 26 HIV-infected and 20 age-matched HC MSM were included. Compared to HC group, CD4/CD8 ratio of HIV-infected group was significantly reduced (0.30 vs. 1.70, P<0.001); significant differences emerged among all CD8 but not CD4 T cell subsets (all P<0.05). In HIV-infected group, the percentages of senescent cells (CD28-CD57+) in TN, TCM, TEM, and TemRA subsets of CD8 T cells were higher (all P<0.05); while a significant difference was only found in naïve CD4 T cells (P<0.05). HLA-DR expression was increased significantly in all CD4 and CD8 T cell subsets. Both naïve (CD45RA+) and memory (CD45RO+) CD8 T cells in this population had significantly shorter telomere length (P<0.01) compared to HC group.

CONCLUSION

HIV-infected MSM exhibit signs of accelerated immune senescence and biological aging, which particularly affects the CD8 T-cell subsets.

Stage-Dependent Within-Individual Comparison Reveals SIV-Specific Activation/Exhaustion Shift in Rhesus Macaques

It is challenging to trace the complicated individual-based variations of HIV-specific immunocompetence shift during the successful antiretroviral therapy (ART) era. Using eight rhesus monkeys simulating a longitudinal stage-dependent cohort (baseline-SIV acute infection-SIV suppression by ART-ART withdrawal), baseline immunocompetence monitoring for 28 days (SIV-negative stage, SN) was compared with host immunocompetence undergoing 90-day ART treatment (SIV-suppressed stage, SS) to reveal the SIV-specific immunity shift aroused by undetectable individual viral replication. During acute SIV infection for 98 days (SIV-emerged stage, SE), immune activation was compared with re-immune activation post ART for 49-day follow-up (SIV-rebounded stage, SR) to reveal the SIV-specific immune activation variation aroused by detectable individual viral replication. Individual immunocompetence was measured by co-expression of CD4, CD8, CD38, HLA-DR, CCR7, CD45RA, and PD-1 on T cells and a cytokine panel. Compared with SN, mild immune activation/exhaustion was characterized by increased CD38⁺ HLA-DR^– CD4⁺/CD8⁺ T-cell subsets and PD-1⁺ memory CD4⁺/CD8⁺ T-cell subsets with three elevated cytokines (MIP-1β, IL-8, and IL-10) significantly emerged in SS. Compared with SE, SR produced more exhaustion characterized by increased PD-1⁺ CD4⁺ T_CM cells and decreased PD-1⁺ CD4⁺ T_EM cells with four elevated pro-inflammatory cytokines (IFN-γ, IL-1β, IL-6, and TNF-α). By such individualized stage-dependent comparison, the sustainable immune activation was found from activation/exhaustion shifted into exhaustion during the longitudinal viral persistence. Further, validated SIV accelerates host immunosenescence continuously independent of viral replication.

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.

Mesenchymal stromal cells in human immunodeficiency virus-infected patients with discordant immune response: Early results of a phase I/II clinical trial

Between 15% and 30% of HIV‐infected subjects fail to increase their CD4⁺ T‐cell counts despite continuous viral suppression (immunological nonresponders [INRs]). These subjects have a higher morbidity and mortality rate, but there are no effective treatments to reverse this situation so far. This study used data from an interrupted phase I/II clinical trial to evaluate safety and immune recovery after INRs were given four infusions, at baseline and at weeks 4, 8, and 20, with human allogeneic mesenchymal stromal cells from adipose tissue (Ad‐MSCs). Based on the study design, the first 5 out of 15 INRs recruited received unblinded Ad‐MSC infusions. They had a median CD4⁺ nadir count of 16/μL (range, 2‐180) and CD4⁺ count of 253 cells per microliter (171‐412) at baseline after 109 (54‐237) months on antiretroviral treatment and 69 (52‐91) months of continuous undetectable plasma HIV‐RNA. After a year of follow‐up, an independent committee recommended the suspension of the study because no increase of CD4⁺ T‐cell counts or CD4⁺/CD8⁺ ratios was observed. There were also no significant changes in the phenotype of different immunological lymphocyte subsets, percentages of natural killer cells, regulatory T cells, and dendritic cells, the inflammatory parameters analyzed, and cellular associated HIV‐DNA in peripheral blood mononuclear cells. Furthermore, three subjects suffered venous thrombosis events directly related to the Ad‐MSC infusions in the arms where the infusions were performed. Although the current study is based on a small sample of participants, the findings suggest that allogeneic Ad‐MSC infusions are not effective to improve immune recovery in INR patients or to reduce immune activation or inflammation. ClinicalTrials.gov identifier: NCT0229004. EudraCT number: 2014‐000307‐26.

Definition of Immunological Nonresponse to Antiretroviral Therapy: A Systematic Review

BACKGROUND

Terms and criteria to classify people living with HIV on antiretroviral therapy who fail to achieve satisfactory CD4 T-cell counts are heterogeneous, and need revision and summarization.

METHODS

We performed a systematic review of PubMed original research articles containing a set of predefined terms, published in English between January 2009 and September 2018. The search retrieved initially 1360 studies, of which 103 were eligible. The representative terminology and criteria were extracted and analyzed.

RESULTS

Twenty-two terms and 73 criteria to define the condition were identified. The most frequent term was "immunological nonresponders" and the most frequent criterion was "CD4 T-cell count <350 cells/µL after ≥24 months of virologic suppression." Most criteria use CD4+ T-cell counts as a surrogate, either as an absolute value or as a change after a defined period of time [corrected]. Distinct values and time points were used. Only 9 of the 73 criteria were used by more than one independent research team. Herein we propose 2 criteria that could help to reach a consensus.

CONCLUSIONS

The high disparity in terms and criteria here reported precludes data aggregation and progression of the knowledge on this condition, because it renders impossible to compare data from different studies. This review will foster the discussion of terms and criteria to achieve a consensual definition.

Frailty, markers of immune activation and oxidative stress in HIV infected elderly

People living with HIV-1 experience an accelerated aging due to the persistent and chronic activation of the immune system. This phenomenon conduces to immune exhaustion and precipitate immunosenescence. In general, frailty is defined as a syndrome of physiological degeneration in the elderly. Circulating naïve and memory T cells were studied by flow cytometry in non-frail and frail HIV-1-infected groups. Thymopoiesis, cell activation, senescence and cell proliferation were analyzed by CD31, HLA-DR/CD38, CD28/CD57 and Ki-67 expression, respectively. Plasma levels of sCD14 and MDA were measured by ELISA. Frail infected individuals showed a reduced number of memory T cells, both CD4+ and CD8+ populations. Activated CD3+CD4+HLA-DR+ T cells were lower in frail individuals, and directly correlated with CD3+CD8+HLA-DR+ and CD8M cells. Senescent CD8+CD28-CD57+ cells were reduced in frail HIV-1 infected individuals and inversely correlated with CD8RTE, CD8N and CD3+CD4+HLA-DR+. Higher plasma levels of sCD14 and MDA were found in HIV-1 infected frail individuals. Our data show association among frailty, markers of immune activation and oxidative stress. Understanding the immune mechanisms underlying frailty status in HIV-1 population is of high relevance not only for the prediction of continuing longevity but also for the identification of potential strategies for the elderly.

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.

Endothelial mitochondrial senescence accelerates cardiovascular disease in antiretroviral-receiving HIV patients

Combination antiretroviral therapy (cART) has been hugely successful in reducing the mortality associated with human immunodeficiency virus (HIV) infection, resulting in a growing population of people living with HIV (PLWH). Since PLWH now have a longer life expectancy, chronic comorbidities have become the focus of the clinical management of HIV. For example, cardiovascular complications are now one of the most prevalent causes of death in PLWH. Numerous epidemiological studies show that antiretroviral treatment increases cardiovascular disease (CVD) risk and early onset of CVD in PLWH. Nucleoside reverse transcriptase inhibitors (NRTIs) are the backbone of cART, and two NRTIs are typically used in combination with one drug from another drug class, e.g., a fusion inhibitor. NRTIs are known to induce mitochondrial dysfunction, contributing to toxicity in numerous tissues, such as myopathy, lipoatrophy, neuropathy, and nephropathy. In in vitro studies, short-term NRTI treatment induces an endothelial dysfunction with an increased reactive oxygen species (ROS) production; long-term NRTI treatment decreases cell replication capacity, while increasing mtROS production and senescent cell accumulation. These findings suggest that a mitochondrial oxidative stress is involved in the pathogenesis of NRTI-induced endothelial dysfunction and premature senescence. Mitochondrial dysfunction, defined by a compromised mitochondrial quality control via biogenesis and mitophagy, has a causal role in premature endothelial senescence and can potentially initiate early cardiovascular disease (CVD) development in PLWH. In this review, we explore the hypothesis and present literature supporting that long-term NRTI treatment induces vascular dysfunction by interfering with endothelial mitochondrial homeostasis and provoking mitochondrial genomic instability, resulting in premature endothelial senescence.

Thymic Function as a Predictor of Immune Recovery in Chronically HIV-Infected Patients Initiating Antiretroviral Therapy

Poor immunological responders (PIR) are HIV-infected patients with virologic suppression upon antiretroviral therapy (ART) but persistently low CD4⁺ T cell counts. Early identification of PIR is important given their higher morbimortality compared to adequate immune responders (AIR). In this study, 33 patients severely lymphopenic at ART onset, were followed for at least 36 months, and classified as PIR or AIR using cluster analysis grounded on their CD4⁺ T cell count trajectories. Based on a variety of immunological parameters, we built predictive models of PIR/AIR outcome using logistic regression. All PIR had CD4⁺ T cell counts consistently below 500 cells/μL, while all AIR reached this threshold. AIR showed a higher percentage of recent thymic emigrants among CD4⁺ T cells; higher numbers of sj-TRECs and greater sj/β TREC ratios; and significant increases in thymic volume from baseline to 12 months of ART. We identified mathematical models that correctly predicted PIR/AIR outcome after 36 months of therapy in 77-87% of the cases, based on observations made until 2-6 months after ART onset. This study highlights the importance of thymic activity in the immune recovery of severely lymphopenic patients, and may help to select the patients that will benefit from closer follow-up or novel therapeutic approaches.

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.

HIV-Infected Subjects With Poor CD4 T-Cell Recovery Despite Effective Therapy Express High Levels of OX40 and α4β7 on CD4 T-Cells Prior Therapy Initiation

Background

HIV-infected subjects with suboptimal CD4 restoration despite suppressive combined antiretroviral treatment (cART) (immunodiscordant subjects) have been classically characterized after a variable period of time under cART. Recently, we have reported that an increased frequency of proliferating CD4 T-cells in these subjects is already present before the cART onset. The potential contribution of peripheral compensatory homeostatic proliferation (HP) is yet unknown. We aimed to analyze the expression of HP-related cellular markers on CD4 T-cells of immunodiscordant subjects before cART.

Methods

We analyzed the expression of OX40 and α4β7 on peripheral CD4 T-cells from immunodiscordant and control subjects (n = 21 each group) before cART initiation, and also on available follow-up samples (after 24 month of suppressive cART). Additionally, we tested the expression of these markers in an in vitro system for the study of human HP processes.

Results

Immunodiscordant subjects showed increased levels of OX40 and α4β7 on CD4 T-cells before cART initiation. While the cART tended to reduce these levels, immunodiscordant subjects still maintained comparatively higher levels of OX40 and α4β7 after 24 months under suppressive cART. These HP-related markers were upregulated in vitro during the human HP, especially during the fast HP.

Conclusion

Our results are compatible with exacerbated HP processes in immunodiscordant subjects, already before the cART onset.

Birth Weight and Preterm Delivery Outcomes of Perinatally vs Nonperinatally Human Immunodeficiency Virus-Infected Pregnant Women in the United States: Results From the PHACS SMARTT Study and IMPAACT P1025 Protocol

Background

Pregnancy outcomes of perinatally human immunodeficiency virus-infected women (PHIV) are poorly defined.

Methods

We compared preterm delivery and birth weight (BW) outcomes (low BW [LBW], <2500 g), small-for-gestational-age [SGA], and BW z scores [BWZ]) in HIV-exposed uninfected infants of PHIV vs nonperinatally HIV-infected (NPHIV) pregnant women in the Pediatric HIV/AIDS Cohort Study Surveillance Monitoring of ART Toxicities or International Maternal Pediatric Adolescent AIDS Clinical Trials P1025 studies. Mixed effects models and log binomial models were used to assess the association of maternal PHIV status with infant outcomes. Age-stratified analyses were performed.

Results

From 1998 to 2013, 2270 HIV-infected pregnant women delivered 2692 newborns (270 born to PHIV and 2422 to NPHIV women). PHIV women were younger, (mean age 21 vs 25 years, P < .01) and more likely to have a pregnancy CD4 count <200 cells/mm3 (19% vs 11%, P = .01). No associations between maternal PHIV status and preterm delivery, SGA, or LBW were observed. After adjustment, BWZ was 0.12 lower in infants of PHIV vs NPHIV women (adjusted mean, -0.45 vs -0.33; P = .04). Among women aged 23-30 years (n = 1770), maternal PHIV was associated with LBW (aRR = 1.74; 95% confidence interval, 1.18, 2.58; P < .01).

Conclusion

The overall lack of association between maternal PHIV status and preterm delivery or infant BW outcomes is reassuring. The higher rates of LBW observed in PHIV women aged 23-30 years warrants further mechanism-based investigations as this is a rapidly growing and aging population worldwide.

Clinical Trials Registration

PHACS SMARTT study, NCT01310023.

Clinical Trials Registration

IMPAACT 1025, NCT00028145.

Alteration of CCR6+CD95+CD4+ naïve T cells in HIV-1 infected patients: Implication for clinical practice

The profound deficiency of Th17 cells contributes to HIV disease progression. The mechanisms of their perturbation remain unclear. Recently, CCR6⁺CD95⁺CD4⁺ naïve T cells (CCR6⁺CD95⁺CD4⁺ T_NA), identified as pre-committed Th17 precursors, were recognized as a subpopulation of CD4⁺ T cells with stem cell properties. Following phenotypical identification, we evaluated their level in patients during chronic HIV infection and following antiretroviral therapy (ART) using flow cytometry. The levels of CCR6⁺CD95⁺CD4⁺ T_NA were decreased during chronic HIV infection and correlated with CD4⁺ T cell counts. Immunological responders harbored higher frequency of CCR6⁺CD95⁺CD4⁺ T_NA, which was associated with CD4/CD8 T cell ratio. Immunological non-responders with lower frequency of CCR6⁺CD95⁺CD4⁺ T_NA failed to exhibit a correlation between CCR6⁺CD95⁺CD4⁺ T_NA and CCR6⁺CD95⁺CD4⁺ T_CM, and displayed elevated ratio of CCR6⁺CD95⁺CD4⁺ T_CM/T_NA. The number of CCR6⁺CD95⁺CD4⁺ T_NA was increased following early ART. These findings shed light on the importance of targeting pre-committed Th17 precursors that enhance immune reconstitution.

Thymic Function Failure Is Associated With Human Immunodeficiency Virus Disease Progression

Background

Thymic function has been mainly analyzed with surrogate peripheral markers affected by peripheral T-cell expansion, making it difficult to assess the role of thymic failure in human immunodeficiency virus (HIV) disease progression. The assay of signal-joint/DβJβ T-cell rearrangement excision circles (sj/β-TREC ratio) overcomes this limitation but has only been assayed in small cohorts. Thus, the aim of this study was to determine the role of thymic function, measured by the sj/β-TREC ratio, on CD4 T-cell maintenance in prospective HIV cohorts that include patients with a wide age range and different immunological phenotypes.

Methods

Seven hundred seventy-four patients including typical progressors, long-term nonprogressors (LTNPs), and vertically HIV-infected subjects were analyzed. Thymic function was quantified in peripheral blood samples using the sj/β-TREC ratio. Associations between thymic function and CD4 T-cell dynamics and combination antiretroviral therapy (cART) onset were analyzed using linear, logistic, and Cox proportional hazard models.

Results

Thymic function failure (sj/β-TREC ratio <10) was independently associated with HIV progression. In agreement, patients with distinctive high CD4 T-cell levels and low progression rates (vertically HIV-infected patients and LTNPs, including HIV controllers) had significantly higher thymic function levels whereas patients with thymic function failure had lower CD4 T-cell levels, lower nadir, and faster CD4 T-cell decay.

Conclusions

This work establishes the relevance of thymic function, measured by sj/β-TREC ratio, in HIV disease progression by analyzing a large number of patients in 3 cohorts with different HIV disease progression phenotypes. These results support and help to understand the mechanisms underlying the rationale of early cART onset.

Preserved immune functionality and high CMV-specific T-cell responses in HIV-infected individuals with poor CD4+ T-cell immune recovery

Poor CD4⁺ T-cell recovery after cART has been associated with skewed T-cell maturation, inflammation and immunosenescence; however, T-cell functionality in those individuals has not been fully characterized. In the present study, we assessed T-cell function by assessing cytokine production after polyclonal, CMV and HIV stimulations of T-cells from ART-suppressed HIV-infected individuals with CD4⁺ T-cell counts >350 cells/μL (immunoconcordants) or <350 cells/μL (immunodiscordants). A group of HIV-uninfected individuals were also included as controls. Since CMV co-infection significantly affected T-cell maturation and polyfunctionality, only CMV⁺ individuals were analyzed. Despite their reduced and skewed CD4⁺ T-cell compartment, immunodiscordant individuals showed preserved polyclonal and HIV-specific responses. However, CMV response in immunodiscordant participants was significantly different from immunoconcordant or HIV-seronegative individuals. In immunodiscordant subjects, the magnitude of IFN-γ⁺ CD8⁺ and IL-2⁺ CD4⁺ T-cells in response to CMV was higher and differently associated with the CD4⁺ T-cell maturation profile., showing an increased frequency of naïve, central memory and EMRA CMV-specific CD4⁺ T-cells. In conclusion, CD4⁺ and CD8⁺ T-cell polyfunctionality was not reduced in immunodiscordant individuals, although heightened CMV-specific immune responses, likely related to subclinical CMV reactivations, may be contributing to the skewed T-cell maturation and the higher risk of clinical progression observed in those individuals.

A Lower Baseline CD4/CD8 T-Cell Ratio Is Independently Associated with Immunodiscordant Response to Antiretroviral Therapy in HIV-Infected Subjects

We explored if baseline CD4/CD8 T-cell ratio is associated with immunodiscordant response to antiretroviral therapy in HIV-infected subjects. Comparing immunodiscordant and immunoconcordant subjects matched by pretreatment CD4 counts, we observed a lower pretreatment CD4/CD8 T-cell ratio in immunodiscordant subjects. Furthermore, pretreatment CD4/CD8 T-cell ratio, but not CD4 counts, correlated with the main immunological alterations observed in immunodiscordants, including increased regulatory T-cell (Treg) frequency and T-cell turnover-related markers. Then, in a larger cohort, only baseline CD4/CD8 T-cell ratio was independently associated with immunodiscordance, after adjusting by the viral CXCR4-tropic HIV variants. Our results suggest that the CD4/CD8 T-cell ratio could be an accurate biomarker of the subjacent immunological damage triggering immunodiscordance.

Higher levels of IL-6, CD4 turnover and Treg frequency are already present before cART in HIV-infected subjects with later low CD4 recovery

Immunological characterization of HIV-infected subjects with low CD4-recovery (LR-subjects) has been extensively performed after a variable period of combined antiretroviral therapy (cART). We now explore immunological alterations present before the cART onset. In a case-control study, we selected pre-cART samples of HIV-subjects with and without low CD4-recovery after cART (n = 21 per group). CD4 T-cell activation, senescence and exhaustion related markers were not found specifically altered before cART initiation. On the other hand, we found that LR-subjects before cART already showed increased levels of IL6 (p = 0.009) and increased frequencies of Ki67+CD4⁺ T-cells (p = 0.026), CD45RA-CD27+CD4⁺ T-cells (p = 0.008) and Treg (p = 0.001), as well as increased expression of CD95 and CD127 on CD4 T-cells (p = 0.016; p = 0.032, respectively). These parameters characterize the immunological damage in LR-subjects before the cART onset and could be associated to the mechanisms hindering the subsequent CD4 recovery.

Increase in frequencies of circulating Th-17 cells correlates with microbial translocation, immune activation and exhaustion in HIV-1 infected patients with poor CD4 T-cell reconstitution

We analyzed the association of circulating Th-17 cells (cTh-17) with immune activation (IA), immune exhaustion (IE) and regulatory T-cells (T-regs) in 20 human immunodeficiency virus-1 (HIV-1) infected patients with impaired restoration of CD4 T-cell counts despite prolonged suppression of plasma viremia (discordant) and compared it with 20 HIV-1 infected patients showing good immunologic and virologic responses (concordant) following highly active antiretroviral therapy (HAART). Discordant HIV-1 infected patients showed significantly higher frequencies of cTh-17 cells compared to concordant patients and healthy controls after PMA+Ionomicin stimulation. Discordant patients also showed higher CD4 T-cell immune activation (HLA-DR+CD38+) than concordant patients which directly correlated with microbial translocation. Additionally, CD4 T-cells of discordant patients showed higher frequencies of CD4 T-cells expressing multiple immune exhaustion markers (Tim3+PD-1+) which correlated with immune activation indicating that combined analysis of inhibitory molecules along with PD-1 might be a better predictor for immune exhaustion of CD4 T-cells. Increased cTh-17 cell frequency correlated inversely with CD4 T-cell percentages and absolute counts and directly with CD4 T-cell immune activation and T-reg frequencies. Persistent CD4 T-cell immune activation might favor differentiation of activated CD4 T-cells toward cTh-17 phenotype in discordant patients. Discordant patients had significantly lower baseline CD4 T-cell counts and higher viral load at the initiation of HAART and higher immune activation and immune exhaustion after being on HAART for long time indicating that these factors might be associated with an increase in cTh-17 cell frequency, thus, increasing the risk of disease progression despite virologic control.

Increased frequency of late-senescent T cells lacking CD127 in chronic hepatitis C disease

BACKGROUND

Hepatitis C virus (HCV) causes persistent disease in ~85% of infected individuals, where the viral replication appears to be tightly controlled by HCV-specific CD8+ T cells. Accumulation of senescent T cells during infection results in considerable loss of functional HCV-specific immune responses.

MATERIALS AND METHODS

We characterized the distinct T-cell phenotypes based on the expression of costimulatory molecules CD28 and CD27, senescence markers PD-1 and CD57, chronic immune activation markers CD38 and HLA-DR, and survival marker CD127 (IL-7R) by flow cytometry following activation of T cells using HCV peptides and phytohemagglutinin.

RESULTS

HCV-specific CD4+ and CD8+ T cells from chronic HCV (CHC) patients showed increased expression of PD-1. Furthermore, virus-specific CD4+ T cells of CHC-infected subjects displayed relatively increased expression of HLA-DR and CD38 relative to HCV-specific CD8+ T cells. The CD4+ and CD8+ T cells from HCV-infected individuals showed significant increase of late-differentiated T cells suggestive of immunosenescence. In addition, we found that the plasma viral loads positively correlated with the levels of CD57 and PD-1 expressed on T cells.

CONCLUSIONS

Chronic HCV infection results in increased turnover of late-senescent T cells that lack survival potentials, possibly contributing to viral persistence. Our findings challenge the prominence of senescent T-cell phenotypes in clinical hepatitis C infection.

Visceral leishmaniasis as an independent cause of high immune activation, T-cell senescence, and lack of immune recovery in virologically suppressed HIV-1-coinfected patients

OBJECTIVES

Different immune alterations have been described in HIV-infected patients with visceral leishmaniasis (VL). We aimed to identify the immunological factors involved in the lack of immunological recovery and VL relapses in HIV-infected patients with VL, by comparison with other HIV-infected patients.

METHODS

We carried out a cross-sectional study of 55 patients receiving suppressive combination antiretroviral therapy (cART) for at least 1 year: nine with previous relapsing VL, 20 with an immunodiscordant response (IDR) to cART (CD4 count < 200 cells/μL) and no previous VL, and 26 with a concordant response (CR) to cART (CD4 count > 350 cells/μL) without VL. Immunosenescence was investigated by analysing CD57(+) CD28(-) levels, immune activation by analysing CD38(+) HLA-DR(+) levels, inflammation by analysing interleukin (IL)-6 levels, and microbial translocation by analysing lipopolysaccharide (LPS) and soluble CD14 (sCD14) levels.

RESULTS

In VL patients, the median time since VL diagnosis was 42 months, and all patients had had at least one relapse despite suppressive cART for a median time of 43 months. Patients with previously diagnosed VL had a higher CD8 T-cell activation level (P < 0.001) than those with IDR. Also, levels of IL-6, LPS and especially sCD14, associated with bacterial translocation and additional monocyte activation, were significantly increased in patients with previous VL compared with patients with IDR (P = 0.048, P = 0.049 and P < 0.001, respectively). In addition, patients with previous VL had higher levels of CD8 T-cell senescence. Notably, the levels of immune activation and inflammation in patients with previous VL were not related to the time of VL diagnosis, the number of VL relapses, or hepatitis C virus (HCV) coinfection.

CONCLUSIONS

Our data demonstrate that VL patients had an even worse immunological status than patients with IDR, which was probably associated with increased microbial translocation and additional monocyte/macrophage activation. These data explain the observed lack of immunological recovery and the occurrence of VL relapses in HIV-infected patients with previous VL.

Immunodiscordant responses to HAART--mechanisms and consequences

A relevant fraction of HIV-1-infected individuals (ranging from 15 to 30%) presenting virologically successful highly active antiretroviral therapy fail to recover CD4 T-cell counts. These individuals, called immunodiscordant or immunological nonresponders, are at increased risk of clinical progression and death. Although older age, lower nadir CD4 T-cell count and HCV co-infection are some of clinical predictive factors, immunological mechanisms rely on impaired thymic production and accumulation of apoptosis-prone CD4 T cells. Indeed, immunodiscordant individuals may show increased tissue fibrosis and damage of gut-associated lymphoid tissue that results in higher hyperactivation, inflammation and immunosenescence, altered Treg/Th17 ratio and increased T-cell death. A better knowledge of the final pathogenic mechanism and factors influencing CD4 T-cell recovery will help to select the optimal therapeutic strategies for them.

Evaluation of the pharmacogenetics of immune recovery in treated HIV-infected patients

INTRODUCTION

Combination antiretroviral therapy has markedly improved the survival rate and quality of life in patients infected with HIV due to the powerful suppressor effect that current antiretroviral drugs have on the viral load. Consequently, the immune system undergoes a substantial qualitative and quantitative improvement; and this leads to an increase in the absolute CD4(+) T-lymphocyte count and the restoration of lost T-cell responses against certain opportunistic pathogens. Unfortunately, not all patients who successfully suppress plasma viremia experience sufficient CD4(+) T-cell gain and these patients, in turn, are associated with worse outcomes. Pharmacogenetic studies have been used to investigate how a patient's genetic predisposition may affect their response to antiretroviral drugs.

AREAS COVERED

This article reviews the investigations that have been published on the association between host genetic determinants of CD4(+) T-cell gain in treated HIV-infected patients. Studies were identified through a PubMed database search. Longitudinal studies into pharmacogenetic association were specifically selected.

EXPERT OPINION

While the possibility of genetic predisposition to HIV therapeutics has potential, most studies provide inconsistent data. Inconsistency is often due to partial genetic evaluation, different categorization of poor immune recovery or due to small numbers of patients evaluated. Currently, studies still belong to the research laboratory stage and more studies are required to improve our understanding.

Prevalence of parasitemia and associated immunodeficiency among HIV-malaria co-infected adult patients with highly active antiretroviral therapy

OBJECTIVE

To investigate the malaria parasitemia, CD4(+) cell counts and some haematological indices among HIV-malaria co-infected adult patients with highly active antiretroviral therapy (HAART).

METHODS

A total of 342 adult HIV positive subjects were recruited at the consultant outpatient HIV/AIDS clinic, University of Benin Teaching Hospital, Benin City, Nigeria between June 2011 to November 2011. Blood samples were taken for malaria parasite count, CD4(+) cell count and other haematological counts.

RESULTS

Out of the 342 adult HIV positive subjects a total of 254 patients (74.3%) were found to have malaria parasitemia. The incidence of malaria parasitemia increased with advancing clinical stage of HIV infection and this was statistically significant (P=0.002). There was no statistical significance when gender was compared with the HIV-malaria status (P >0.05). Of the 254 co-infected patients, 134 (52.8%) had high parasitemia (>1.25 × 10(9)/L). Sixty patients were found to be hyperparasitemic (>2.5 parasites/L). There was a significant association between CD4(+) cell count and having significant parasitemia (P < 0.000 1). About half (50.8%) of co-infected patients had CD4(+) cell count ≤ 200/μL, and majority (44.9%) of this population also had significant parasitemia. Anaemia and thrombocytopenia were not significantly associated with HIV-malaria co-infection (P > 0.05).

CONCLUSIONS

The prevalence of parasitemia is high among the HIV/AIDS infected patients.

Incidence and clinical and immunological characteristics of primary Toxoplasma gondii infection in HIV-infected patients

OBJECTIVES

To determine the incidence and laboratory characteristics of primary Toxoplasma gondii infection in HIV-infected individuals.

METHODS

This retrospective study was conducted between 1988 and 2012 on a cohort of 1130 HIV-infected patients at the AIDS Center Prague. Toxoplasma serology, standard laboratory parameters, and health status were evaluated at 3-6-month intervals for all patients.

RESULTS

The total person-time of follow-up of patients at risk of Toxoplasma seroconversion was 3046.3 years; there were 14 primary T. gondii infections, yielding an incidence rate of 0.0046 (95% confidence interval 0.0027-0.0078). Most of the subjects were clinically asymptomatic, but in one case seroconversion was accompanied by transient cervical lymphadenopathy. The CD4+ T-lymphocyte count geometric mean increased from 418 (95% confidence interval 303-579) cells/μl before seroconversion to 501 (95% confidence interval 363-691) cells/μl after seroconversion (p = 0.004), while other parameters (CD8+ T-lymphocytes, natural killer cells, viral load, beta2-microglobulin, total immunoglobulins) remained unchanged. As compared to the control group, patients with primary toxoplasmosis had higher initial levels of total immunoglobulins IgA and IgG and a tendency to higher CD8+ T lymphocyte counts.

CONCLUSIONS

Neither the incidence nor the course of the primary Toxoplasma infection was influenced by the immune status of the patients. Immune parameters of patients with primary Toxoplasma infection did not differ from those of the controls.

Assessing main death pathways in T lymphocytes from HIV infected individuals

Increased lymphocyte death is a hallmark of human immunodeficiency virus (HIV) infection. Although virological factors have been linked to this phenomenon, increased cell death rates are still observed in treated individuals in which viral replication is halted. To understand the nature of this remaining altered cell death, we have developed a simple and fast assay to assess major cell death pathways in lymphocytes isolated from HIV-infected individuals. The combination of three factors: (i) antibody staining to identify CD3(+) CD4(+) and CD3(+) CD8(+) cells, (ii) assessment of mitochondrial and plasma membrane function using DiOC6(3) or JC-1 probes and vital dyes, and (iii) caspase inhibition, allowed for the quantification of caspase-independent and -dependent cell death in CD4 and CD8 T cells. The latter mechanism was divided in intrinsic and extrinsic apoptotic pathways according to the sensitivity of the dissipation of mitochondrial membrane potential to Z-VAD-fmk or Q-VD-oPH treatment. Our data show similar results for both caspase inhibitors in treated infected individuals, whereas Q-VD-oPH showed a more potent inhibition in viremic individuals, yielding lower levels of intrinsic apoptosis. Comparison of DiOC6(3) and JC-1 probes yielded similar results in CD4 T cells, allowing for a clear definition of death mechanism in these cells. However, in CD8 T-cells, JC-1 showed heterogeneous staining and detected significantly lower levels of cell death with a higher contribution of intrinsic apoptosis. In conclusion, we provide a simple method to assess CD4 T-cell death mechanisms in HIV-infected individuals. The reasons and consequences of mitochondrial heterogeneity in CD8 T-cells require further evaluation.

Thymic function failure and C-reactive protein levels are independent predictors of all-cause mortality in healthy elderly humans

Relationship between thymic function and elderly survival has been suspected, despite the fact that formal proof is elusive due to technical limitations of thymic function-related markers. The newly described sj/β-TREC ratio allows now, by overcoming these limitations, an accurate measurement of thymic output in elderly humans. Thus, the aim of this study was to determine the impact of thymic function and inflammatory markers on healthy elderly human survival. Healthy volunteers (n = 151), aged over 65, were asked to participate (CARRERITAS cohort). Subjects were excluded if diagnosed of dementia or, during the last 6 months, had clinical data of infection, hospital admission, antitumor therapy, or any treatment that could influence the immune status. Thymic function (sj/β-TREC ratio), CD4:CD8 T cell ratio, C-reactive protein, interleukin-6, and neutrophilia were determined from basal samples. All basal variables and age were associated with 2-year all-cause mortality. Multivariate analysis showed that only thymic function and C-reactive protein were independently associated with time to death. In conclusion, we show, for the first time, the direct role of thymic function in human survival. C-reactive protein raise is also a marker of mortality in the healthy elderly, in a thymic-independent way.

Impact of age on markers of HIV-1 disease

Aging is a complicated process characterized by a progressive loss of homeostasis, which results in an increased vulnerability to multiple diseases. HIV-1-infected patients demonstrate a premature aging phenotype and develop certain age-related diseases earlier in their lifespan than what is seen in the general population. Age-related comorbidities may include the development of bone disease, metabolic disorders, neurologic impairment and immunosenescence. Age also appears to have an effect on traditional markers of HIV-1 disease progression, including CD4+ T-cell count and viral load. These effects are not only a consequence of HIV-1 infection, but in many cases, are also linked to antiretroviral therapy. This review summarizes the complex interplay between HIV-1 infection and aging, and the impact that aging has on markers of HIV-1 disease.

Specific patterns of CD4-associated immunosenescence in vertically HIV-infected subjects

Vertical transmission of human immunodeficiency virus (HIV) represents an important world-wide health problem although the incidence in developed countries has been drastically reduced by the extensive use of highly active antiretroviral therapy. Vertically HIV-infected subjects have been exposed to the virus during the maturation of their immune systems and have suffered a persistent chronic activation throughout their lifetime; the consequences of this situation for their immune system are not fully understood. The objective of this study was to analyse immunosenescence-related parameters in different CD4 T-cell subsets. Fifty-seven vertically HIV-infected subjects and 32 age-matched healthy subjects were studied. Activation (HLA(-) DR(+) ), senescence (CD28(-) CD57(+) ) and proliferation (Ki67(+) ) were analysed on different CD4 T-cell subsets: naive (CD45RA(+) CD27(+) ), memory (CD45RO(+) CD27(+) ), effector memory (CD45RO(+) CD27(-) ) and effector memory RA (CD45RA(+) CD27(-) ). Compared with healthy subjects, vertically HIV-infected subjects showed increased naive and memory CD4 T-cell frequencies (p 0.035 and p 0.010, respectively) but similar frequencies of both effector subsets. Whereas naive CD4 T cells were not further altered, memory CD4 T cells presented increased levels of senescence and proliferation markers (p <0.001), effector memory CD4 T cells presented increased levels of activation, senescence and proliferation markers (p <0.001) and effector memory RA CD4 T cells presented increased levels of activation and senescence (p <0.001) compared with healthy subjects. Despite long periods of infection, vertically HIV-infected subjects show specific patterns of immunosenescence, revealing a preserved CD4 T-cell homeostasis for subset differentiation and distribution. Nevertheless, excepting the naive subpopulation, all subsets experienced some immunosenescence, pointing to uncertain consequences of the future aging process in these subjects.

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.

Severe immune dysregulation affects CD4⁺CD25(hi)FoxP3⁺ regulatory T cells in HIV-infected patients with low-level CD4 T-cell repopulation despite suppressive highly active antiretroviral therapy

We hypothesized that CD4(+)CD25(hi)FoxP3(+) regulatory T cells (Tregs) could be involved in the high immune activation existing in patients with low-level CD4 T-cell repopulation under suppressive high active antiretroviral therapy (hereafter, "LLR patients"). Sixteen LLR patients, 18 human immunodeficiency virus (HIV)-infected controls (hereafter, "HIV controls"), and 16 healthy subjects were included. The frequency of CD4(+)CD25(hi)FoxP3(+) and HIV-specific Treg suppressive function were assessed. Relationships between Treg and CD4/CD8 activation (HLA-DR/CD38) and the frequency of naive CD4 T-cells were assessed. Low-level patients showed a higher Treg frequency but reduced HIV-specific immunosuppressive functions than HIV controls. Whereas in healthy subjects a strong negative correlation between Tregs and activated CD8 T cells emerged (r = -0.75, P < .001), it appeared disrupted in both HIV-infected groups (r = -0.06 and P = .83 for LLR patients; r = -0.11 and P = .68 for and HIV controls). Nevertheless, in LLR patients, Tregs negatively correlated with naive CD4 T cells (r = -0.60, P = .01), whereas there was no such correlation in HIV controls (r = -0.19, P = .46) or healthy subjects (r = -0.10, P = .73). Remarkably, a higher ratio of Tregs to naive CD4 T cells was observed in LLR patients than in HIV controls (P = .001) and healthy subjects (P < .001). We conclude that LLR patients have important alterations in immunoregulation involving CD4(+)CD25(hi)FoxP3(+) Tregs. In this scenario, the role of Tregs seems to be more related to the control of the naive CD4 T-cell homeostatic proliferation, rather than to the immune activation.

HIV infection and aging of the innate immune system

The increased life expectancy of HIV-infected individuals due to improved treatment has revealed an unexpected increase in non-AIDS comorbidities that are typically associated with older age including cardiovascular disease, dementia and frailty. The majority of these diseases arise as the result of dysregulated systemic inflammation, and both the aged and HIV-infected individuals exhibit elevated basal levels of inflammation. In the elderly, increased inflammation and age-related diseases are associated with a state of impaired immunity called immunosenescence, which is thought to result from a lifetime of immune stimulation. It is now apparent that HIV induces premature immunosenescence within T-cells; however, the impact of HIV on aging of cells of the innate arm of the immune system is unknown. Innate immune cells play a central role in inflammation and are thus critical for the pathogenesis of inflammatory diseases. Limited evidence suggests HIV infection mimics age-related changes to innate immune cells; however, the extent of this effect and the mechanism underlying these changes remain to be defined. This review focuses on the impact of HIV infection on the function and aging of innate immune cells and discusses potential drivers of premature immunosenescence including chronic endotoxaemia, residual viraemia, telomere attrition and altered cellular signalling.

Induction of strong HIV-1-specific CD4+ T-cell responses using an HIV-1 gp120/NefTat vaccine adjuvanted with AS02A in antiretroviral-treated HIV-1-infected individuals

BACKGROUND

Induction of HIV-1-specific CD4(+) T-cell responses by therapeutic vaccination represents an attractive intervention to potentially increase immune control of HIV-1.

METHODS

We performed a double-blinded, randomized, placebo-controlled clinical trial to determine the safety and immunogenicity of GlaxoSmithKline Biologicals' HIV-1 gp120/NefTat subunit protein vaccine formulated with the AS02(A) Adjuvant System in subjects with well-controlled chronic HIV-1 infection on highly active antiretroviral therapy. Ten individuals received the vaccine; whereas adjuvant alone or placebo was given to 5 subjects each. Immunogenicity was monitored by intracellular cytokine flow cytometry and carboxyfluorescein succinimidyl ester-based proliferation assays.

RESULTS

The vaccine was well tolerated with no related serious adverse events. Vaccine recipients had significantly stronger gp120-specific CD4(+) T-cell responses which persisted until week 48 and greater gp120-specific CD4(+) T-cell proliferation activity as compared with controls. In the vaccine group, the number of participants who demonstrated positive responses for both gp120-specific CD4(+) T-cell interleukin-2 production and gp120-specific CD8(+) T-cell proliferation were significantly higher at week 6.

CONCLUSIONS

The gp120/NefTat/AS02(A) vaccine induced strong gp120-specific CD4(+) T-cell responses and a higher number of vaccinees developed both HIV-1-specific CD4(+) T-cell responses and CD8(+) T-cell proliferation. The induction of these responses may be important in enhancing immune-mediated viral control.

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.

T-cell signalling in antiretroviral-treated, aviraemic HIV-1-positive individuals is present in a raised state of basal activation that contributes to T-cell hyporesponsiveness

OBJECTIVE

Successful antiretroviral therapy (ART) suppresses plasma HIV-1 RNA below detection limits, reducing the chronic insult to the immune systems of infected individuals and supporting a degree of immunological recovery. However, the surface phenotypic profile of T cells in ART-treated patients does not resemble that of healthy, uninfected individuals, but rather shows upregulation of proteins associated with an exhausted immune system. We sought to address whether aviraemic HIV-1 infection, therefore, contributed to long-term alterations in intracellular signalling events within the T cells of infected individuals that contributed to the exhausted phenotype.

DESIGN

A flow cytometric approach was employed to assess levels of phosphorylation within T-cell signalling proteins in ART-treated HIV-1-positive patients and HIV-negative individuals.

METHODS

The relative phosphorylation levels of extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), p38, zeta-chain-associated protein kinase 70 (ZAP70), linker of activated T cells, SLP76, nuclear factor kappaB were measured within resting and stimulated CD4(+) and CD8(+) T cells from aviraemic HIV-1-positive and healthy individuals by intracellular staining and flow cytometric analysis.

RESULTS

Basal levels of phospho-ZAP70, phospho-ERK and phospho-JNK were two-fold to three-fold higher in HIV-1-positive individuals compared with healthy controls, with phospho-p38 also showing a tendency to increase in HIV-1-positive individuals. Interestingly, in contrast to healthy controls, peripheral blood mononuclear cells from aviraemic, infected individuals were refractory to stimulation with IL-2 and CD3/CD28 showing no enhancement of phosphorylation.

CONCLUSION

CD4(+) and CD8(+) T cells from HIV-1-positive individuals are poorly responsive to direct stimulation through the T-cell receptor due to chronically raised basal activation levels of intracellular signalling molecules.

Cocaine reduces thymic endocrine function: another mechanism for accelerated HIV disease progression

Thymulin is a thymic peptide important for the maturation and differentiation of immature thymocytes, which have been found to be depressed in patients with low-level CD4(+) cell recovery despite viral control. Substance use is associated with faster progression of HIV disease, which has been ascribed to poor adherence to antiretroviral medication. Recent findings of an association between cocaine use and decline in CD4(+) cell counts independent of antiretroviral adherence indicate alternative mechanisms for disease progression. We evaluated the relationship between thymulin activity, CD4(+) and CD8(+) cell counts and the CD4(+)/CD8(+) ratio, and the covariate effects of substance use cross-sectionally in 80 HIV(+) active substance users and over 12 months in 40 participants. Thymulin activity was analyzed in plasma using a modification of the sheep rosette bioassay. Thymulin activity was negatively associated with cocaine use (β = -0.908,95% CI: -1.704, -0.112; p = 0.026). Compared to those who do not use cocaine, cocaine users were 37% less likely to have detectable thymulin activity (RR = 0.634, 95% CI: 0.406, 0.989 p = 0.045) and were 75 times more likely to show a decrease in thymulin activity (OR = 74.7, 95% CI: 1.59, 3519.74; p = 0.028) over time. CD4(+) cell count was positively associated with thymulin activity (β = 0.127, 95% CI: 0.048,0.205; p = 0.002), detectable thymulin activity was 2.32 times more likely in those with a CD4 cell count ≥200 cells/μl (RR = 2.324, 95% CI: 1.196, 4.513, p = 0.013), and those with an increase in CD4 cell counts were more likely to show an increase in thymulin activity (OR = 1.02, 95% CI: 1.00, 1.034; p = 0.041) over time. Thymulin activity is predictive of HIV disease progression and is depressed in cocaine users independent of antiretroviral treatment (ART) and HIV viral load. Understanding the mechanisms for accelerated HIV disease progression provides opportunities to find alternative strategies to counteract immunosuppression.

[Immunopathogenesis of HIV infection]

Killing of CD4 lymphocytes and systemic immune suppression are the hallmarks of HIV infection. These milestones are produced by different mechanisms that draw a complex picture of AIDS immunopathogenesis. The role of the GALT system as a preferential target for HIV, chronic activation of the immune system and viral escape mechanisms are recent challenges that have changed our current view on the mechanisms leading to immune destruction and development of AIDS. In this article, the mechanisms of immune suppression, the evolution of immune response throughout the infection and the mechanisms of viral escape are analysed.

Association between use of HMG CoA reductase inhibitors and mortality in HIV-infected patients

INTRODUCTION

HIV infection is a disease associated with chronic inflammation and immune activation. Antiretroviral therapy reduces inflammation, but not to levels in comparable HIV-negative individuals. The HMG-coenzyme A reductase inhibitors (statins) inhibit several pro-inflammatory processes and suppress immune activation, and are a logical therapy to assess for a possible salutary effect on HIV disease progression and outcomes.

METHODS

Eligible patients were patients enrolled in the Johns Hopkins HIV Clinical Cohort who achieved virologic suppression within 180 days of starting a new highly active antiretroviral therapy (HAART) regimen after January 1, 1998. Assessment was continued until death in patients who maintained a virologic suppression, with right-censoring of their follow-up time if they had an HIV RNA > 500 copies/ml. Cox proportional hazards regression was used to assess statin use as a time-varying covariate, as well as other demographic and clinical factors.

RESULTS

A total of 1538 HIV-infected patients fulfilled eligibility criteria, of whom 238 (15.5%) received a statin while taking HAART. There were 85 deaths (7 in statin users, 78 in non-users). By multivariate Cox regression, statin use was associated with a relative hazard of 0.33 (95% CI: 0.14, 0.76; P =  0.009) after adjusting for CD4, HIV-1 RNA, hemoglobin and cholesterol levels at the start of HAART, age, race, HIV risk group, prior use of ART, year of HAART start, NNRTI vs. PI-based ART, prior AIDS-defining illness, and viral hepatitis coinfection. Malignancy, non-AIDS-defining infection and liver failure were particularly prominent causes of death.

DISCUSSION

Statin use was associated with significantly lower hazard of dying in these HIV-infected patients who were being effectively treated with HAART as determined by virologic suppression. Our results suggest the need for confirmation in other observational cohorts, and if confirmed, the need for a clinical trial of statin use in HIV infection.

Reduced immune response to influenza A (H1N1) 2009 monovalent vaccine in HIV-infected Japanese subjects

We evaluated the immunogenicity and safety of the influenza A (H1N1) 2009 monovalent vaccine in HIV-infected Japanese subjects. A total of 182 HIV-infected and 42 HIV-uninfected subjects were enrolled, and antibody (ab) titers were measured by hemagglutination-inhibition assay at baseline and 32.3±10.4 and 29.7±3.3 days after vaccination, respectively. In the HIV-infected cohort, ab titers ≥ 1:40 at baseline and post-vaccination were 12.6% and 49.5%, respectively. The seroconversion rate, defined as either an ab titer ≤ 1:10 before and ≥ 1:40 after or ≥ 1:10 before and ≥ 4-fold increase in ab titer, was only 38.5% in the HIV-infected cohort, whereas the rate was 85.7% in the HIV-uninfected cohort. Multivariate logistic regression analysis showed that the CD4 cell count was the only significant predictor of a positive vaccine response. There were no serious adverse events in any of the subjects receiving the vaccine. Additional study is warranted to identify a more effective method of vaccinating HIV-infected Japanese subjects.

HIV infection, inflammation, immunosenescence, and aging

Although antiretroviral therapy for HIV infection prevents AIDS-related complications and prolongs life, it does not fully restore health. Long-term treated patients remain at higher than expected risk for a number of complications typically associated with aging, including cardiovascular disease, cancer, osteoporosis, and other end-organ diseases. The potential effect of HIV on health is perhaps most clearly exhibited by a number of immunologic abnormalities that persist despite effective suppression of HIV replication. These changes are consistent with some of the changes to the adaptive immune system that are seen in the very old ("immunosenescence") and that are likely related in part to persistent inflammation. HIV-associated inflammation and immunosenescence have been implicated as causally related to the premature onset of other end-organ diseases. Novel therapeutic strategies aimed at preventing or reversing these immunologic defects may be necessary if HIV-infected patients are to achieve normal life span.

Immunogenicity of a monovalent 2009 influenza A (H1N1) vaccine in an immunocompromised population: a prospective study comparing HIV-infected adults with HIV-uninfected adults

BACKGROUND

Limited data exist on the immunogenicity of the 2009 influenza A (H1N1) vaccine among immunocompromised persons, including those with human immunodeficiency virus (HIV) infection.

METHODS

We compared the immunogenicity and tolerability of a single dose of the monovalent 2009 influenza A (H1N1) vaccine (strain A/California/7/2009H1N1) between HIV-infected and HIV-uninfected adults 18-50 years of age. The primary end point was an antibody titer of ≥ 1:40 at day 28 after vaccination in those with a prevaccination level of ≤ 1:10, as measured by hemagglutination-inhibition assay. Geometric mean titers, influenza-like illnesses, and tolerability were also evaluated.

RESULTS

One hundred thirty-one participants were evaluated (65 HIV-infected and 66 HIV-uninfected patients), with a median age of 35 years (interquartile range, 27-42 years). HIV-infected persons had a median CD4 cell count of 581 cells/mm(3) (interquartile range, 476-814 cells/mm(3)) , and 82% were receiving antiretroviral medications. At baseline, 35 patients (27%) had antibody titers of >1:10. HIV-infected patients (29 [56%] of 52), compared with HIV-uninfected persons (35 [80%] of 44), were significantly less likely to develop an antibody response (odds ratio, .20; P = .003). Changes in the median geometric mean titer from baseline to day 28 were also significantly lower in HIV-infected patients than in HIV-uninfected persons (75 vs 153; P = .001). Five influenza-like illnesses occurred (2 cases in HIV-infected persons), but none was attributable to the 2009 influenza H1N1 virus. The vaccine was well tolerated in both groups.

CONCLUSIONS

Despite high CD4 cell counts and receipt of antiretroviral medications, HIV-infected adults generated significantly poorer antibody responses, compared with HIV-uninfected persons. Future studies evaluating a 2-dose series or more-immunogenic influenza A (H1N1) vaccines among HIV-infected adults are needed (ClinicalTrials.gov NCT00996970).