Detectable viral load aggravates immunosenescence features of CD8 T-cell subsets in vertically HIV-infected children

The role of TEMRA cell-mediated immune senescence in the development and treatment of HIV disease

Human Immunodeficiency Virus (HIV) has plagued human society for a long time since its discovery, causing a large number of patients to suffer and costing hundreds of millions of medical services every year. Scientists have found that HIV and antiretroviral therapy accelerate immune aging by inducing mitochondrial dysfunction, and that terminal effector memory T cells (TEMRA cells) are crucial in immune aging. This specific subset of effector memory T cells has terminally differentiated properties and exhibits high cytotoxicity and proinflammatory capacity. We therefore explored and described the interplay between exhaustion features, essential markers, functions, and signaling pathways from previous studies on HIV, antiretroviral therapy, immune senescence, and TEMRA cells. Their remarkable antiviral capacity is then highlighted by elucidating phenotypic changes in TEMRA cells during HIV infection, describing changes in TEMRA cells before, during, and after antiretroviral therapy and other drug treatments. Their critical role in complications and cytomegalovirus (CMV)-HIV superinfection is highlighted. These studies demonstrate that TEMRA cells play a key role in the antiviral response and immune senescence during HIV infection. Finally, we review current therapeutic strategies targeting TEMRA cells that may be clinically beneficial, highlight their potential role in HIV-1 vaccine development, and provide perspectives and predictions for related future applications.

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.

The struggle of a good friend getting old: cellular senescence in viral responses and therapy

Cellular senescence is a state of stable cell cycle arrest associated with macromolecular alterations and secretion of pro-inflammatory cytokines and molecules. Senescence-associated phenotypes restrict damage propagation and activate immune responses, two essential processes involved in response to viral infections. However, excessive accumulation and persistence of senescent cells can become detrimental and promote pathology and dysfunctions. Various pharmacological interventions, including antiviral therapies, lead to aberrant and premature senescence. Here, we review the molecular mechanisms by which viral infections and antiviral therapy induce senescence. We highlight the importance of these processes in attenuating viral dissemination and damage propagation, but also how prematurely induced senescent cells can promote detrimental adverse effects in humans. We describe which sequelae due to viral infections and treatment can be partly due to excessive and aberrant senescence. Finally, we propose that pharmacological strategies which eliminate senescent cells or suppress their secretory phenotype could mitigate side effects and alleviate the onset of additional morbidities. These strategies can become extremely beneficial in patients recovering from viral infections or undergoing antiviral therapy.

Real-World Analysis of Survival and Clinical Events in a Cohort of Italian Perinatally HIV-1 Infected Children From 2001 to 2018

Background: Combined antiretroviral therapy (cART) has been associated with a steep decrease in mortality and morbidity in HIV-1 infected children. New antiretroviral molecules and drug classes have been developed and the management of HIV-infected children has improved, but recent data on survival are limited. Methods: An observational retrospective study investigating changes in mortality and morbidity was conducted on 1,091 perinatally HIV-1 infected children enrolled in the Italian Register for HIV Infection in Children and followed-up from 2001 to 2018. Results: Three hundred and fifty-four (32%) AIDS events and 26 (2%) deaths occurred overtime. Mortality rates decreased from 0.4/100 person-years in 2001-2006 to 0.27/100 person-years in 2007-2012 and 0.07/100 person-years in 2013-2018. Notably, 92% of the dead children were born in Italy, but only 50% were followed-up since birth or within three months of age. Seventy three percent of children had started cART at age ≥6 months; 23% were treated for <30 days before death. B and C clinical events progressively decreased (P < 0.0001). Opportunistic infections significantly decreased over time, but still were the most common events in all the periods (6.76/100 person-years in 2013-2018). In the last period, severe bacterial infections were the most common ones. Cancer rates were 0.07/100; 0.17/100; 0.07/100 person-years in the three periods, respectively. Conclusions: Progressive reductions both in mortality and in rates of class B and C clinical events and OIs have been observed during the cART era. However, deaths were still registered; more than half of dead children were enrolled after birth and had belatedly started cART.

Nanoparticle-Delivered HIV Peptides to Dendritic Cells a Promising Approach to Generate a Therapeutic Vaccine

Finding a functional cure for HIV-1 infection will markedly decrease the social and economic burden of this disease. In this work, we have taken advantage of the antigen presenting cell role of human dendritic cells (DCs) to try to induce an immune response to HIV-derived peptide delivered to DCs using two different polycationic nanoparticles: a G4 PAMAM dendrimer modified to a 70/30 ratio of hydroxyl groups/amines and a cyclodextrin derivative. We have studied peptide delivery using a fluorescence peptide and have studied the immune response generation by cytokine determination and flow cytometry. We have found a robust delivery of the antigenic peptide to DCs and activated dendritic cell-mediated peripheral blood mononuclear cells (PBMCs) proliferation using the mixed lymphocyte reaction. However, no expression of markers indicating activation of either B or T lymphocytes was observed. Moreover, the release of the pro-inflammatory cytokine TNF-α or IL-2 was only observed when DCs treated with either the dendrimer or the dendriplex containing the peptide. Antigenic peptide delivery to DCs is a promising approach to generate a vaccine against HIV-1 infection. However, more studies, including the simultaneous delivery of several antigenic peptides from different viral proteins, can markedly improve the immune response.

Biological Aging and Immune Senescence in Children with Perinatally Acquired HIV

Chronic HIV-infected children suffer from premature aging and aging-related diseases. Viral replication induces an ongoing inflammation process, with the release of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), the activation of the immune system, and the production of proinflammatory cytokines. Although combined highly active antiretroviral therapy (ART) has significantly modified the natural course of HIV infection, normalization of T and B cell phenotype is not completely achievable; thus, many HIV-infected children display several phenotypical alterations, including higher percentages of activated cells, that favor an accelerated telomere attrition, and higher percentages of exhausted and senescent cells. All these features ultimately lead to the clinical manifestations related to premature aging and comorbidities typically observed in older general population, including non-AIDS-related malignancies. Therefore, even under effective treatment, the premature aging process of HIV-infected children negatively impacts their quality and length of life. This review examines the available data on the impact of HIV and ART on immune and biological senescence of HIV-infected children.

Accelerated aging in perinatally HIV-infected children: clinical manifestations and pathogenetic mechanisms

Background: Premature aging and related diseases have been documented in HIV-infected adults. Data are now emerging also regarding accelerated aging process in HIV-infected children.

Methods: A narrative review was performed searching studies on PubMed published in English language in 2004-2017, using appropriate key words, including “aging”, “children”, “HIV”, “AIDS”, “immunosenescence”, “pathogenesis”, “clinical conditions”.

Results: Premature immunosenescence phenotype of B and T cells in HIV-infected children is mediated through immune system activation and chronic inflammation. Ongoing inflammation processes have been documented by increased levels of pathogen-associated molecular patterns (PAMPS), increased mitochondrial damage, higher levels of pro-inflammatory cytokines, and a positive correlation between sCD14 levels and percentages of activated CD8⁺ cells. Other reported features of premature aging include cellular replicative senescence, linked to an accelerated telomeres shortening. Finally, acceleration of age-associated methylation pattern and other epigenetic modifications have been described in HIV-infected children. All these features may favor the clinical manifestations related to premature aging. Lipid and bone metabolism, cancers, cardiovascular, renal, and neurological systems should be carefully monitored, particularly in children with detectable viremia and/or with CD4/CD8 ratio inversion.

Conclusion: Aging processes in children with HIV infection impact their quality and length of life. Further studies regarding the mechanisms involved in premature aging are needed to search for potential targets of treatment.

Prognostic factors of a lower CD4/CD8 ratio in long term viral suppression HIV infected children

BACKGROUND

Combination antiretroviral therapy (cART) is associated with marked immune reconstitution. Although a long term viral suppression is achievable, not all children however, attain complete immunological recovery due to persistent immune activation. We use CD4/CD8 ratio like a marker of immune reconstitution.

METHODS

Perinatal HIV-infected children who underwent a first-line cART, achieved viral suppression in the first year and maintained it for more than 5 years, with no viral rebound were included. Logistic models were applied to estimate the prognostic factors, clinical characteristics at cART start, of a lower CD4/CD8 ratio at the last visit.

RESULTS

146 HIV-infected children were included: 77% Caucasian, 45% male and 28% CDC C. Median age at cART initiation was 2.3 years (IQR: 0.5-6.2). 42 (30%) children received mono-dual therapy previously to cART. Time of undetectable viral load was 9.5 years (IQR: 7.8, 12.5). 33% of the children not achieved CD4/CD8 ratio >1. Univariate analysis showed an association between CD4/CD8 <1 with lower CD4 nadir and baseline CD4; older age at diagnosis and at cART initiation; and a previous exposure to mono-dual therapy. Multivariate analysis also revealed relationship between CD4/CD8 <1 and lower CD4 nadir (OR: 1.002, CI 95% 1.000-1.004) as well as previous exposure to mono-dual therapy (OR: 0.16, CI 95% 0.003-0.720).

CONCLUSIONS

CD4/CD8 >1 was not achieved in 33% of the children. Lower CD4 nadir and previous exposure to suboptimal therapy, before initiating cART, are factors showing independently association with a worse immune recovery (CD4/CD8 < 1).

Immune Activation, Inflammation, and Non-AIDS Co-Morbidities in HIV-Infected Patients under Long-Term ART

Despite effective antiretroviral therapy (ART), people living with HIV (PLWH) still present persistent chronic immune activation and inflammation. This condition is the result of several factors including thymic dysfunction, persistent antigen stimulation due to low residual viremia, microbial translocation and dysbiosis, caused by the disruption of the gut mucosa, co-infections, and cumulative ART toxicity. All of these factors can create a vicious cycle that does not allow the full control of immune activation and inflammation, leading to an increased risk of developing non-AIDS co-morbidities such as metabolic syndrome and cardiovascular diseases. This review aims to provide an overview of the most recent data about HIV-associated inflammation and chronic immune exhaustion in PLWH under effective ART. Furthermore, we discuss new therapy approaches that are currently being tested to reduce the risk of developing inflammation, ART toxicity, and non-AIDS co-morbidities.

Low Bone Mineral Density in Vertically HIV-infected Children and Adolescents: Risk Factors and the Role of T-cell Activation and Senescence

BACKGROUND

Our aim was to determine the prevalence and risk factors associated with low bone mineral density (BMD) in vertically HIV-infected patients and to investigate whether low BMD is related to immune activation and senescence induced by HIV infection.

METHODS

A cross-sectional study was performed in 98 vertically HIV-infected patients. BMD was measured by dual-energy radiograph absorptiometry at lumbar spine. Height adjustment of BMD Z score was performed using height-for-age Z score. T-cell immune activation and senescence were analyzed in a subgroup of 54 patients by flow cytometry.

RESULTS

Median age was 15.9 years, 71.4% were Caucasian, 99% received antiretroviral therapy and 80.6% had undetectable viral load. Low BMD (BMD Z score ≤ -2) was present in 15.3% of cases, but after height adjustment in 4.1% of cases. Height-adjusted BMD Z score was positively correlated with body mass index Z score, CD4/CD8 ratio and nadir CD4, and inversely with duration of severe immunosuppression and parathyroid hormone values. In the multivariate model including age, gender, ethnicity, encephalopathy, Tanner stage, nadir CD4, duration of viral suppression, CD4 count, CD4/CD8 ratio, body mass index, cumulative duration of antiretroviral therapy, tenofovir and protease inhibitors exposure, nadir CD4 was independently associated to height-adjusted BMD Z score. No association was found between height-adjusted BMD Z score and T-cell activation or senescence.

CONCLUSIONS

The prevalence of low BMD in vertically HIV-infected patients was low after height adjustment. Nadir CD4, but not T-cell activation or senescence, was an independent predictor for low BMD. Larger and prospective studies are needed to achieve better knowledge of the pathogenesis of low BMD in vertical HIV infection.

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.

Abnormal Bone Acquisition With Early-Life HIV Infection: Role of Immune Activation and Senescent Osteogenic Precursors

Chronic immune activation associated with human immunodeficiency virus (HIV) infection may have negative consequences on bone acquisition in individuals infected with HIV early in life. Bone mineral density (BMD) and microarchitecture were characterized in 38 HIV-infected men on antiretroviral therapy (18 perinatally-infected, 20 adolescence-infected) and 20 uninfected men age 20 to 25 years by dual-energy X-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HRpQCT). Flow cytometry was utilized to measure CD4+/CD8+ activation (HLADR+CD38+) and senescence (CD28-CD57+) and to quantify circulating osteogenic precursor (COP) cells in peripheral blood mononuclear cells using antibodies to RUNX2 and osteocalcin (OCN). Telomere lengths were measured in sorted COP cells using qPCR. DXA-derived areal BMD Z-scores and HRpQCT-derived volumetric BMD (vBMD) measures were lower in HIV-infected than uninfected men. Proportion of activated and senescent CD4+ and CD8+ T cells were higher in HIV-infected than uninfected men. The percentage of COP cells (mean ± SE) was lower in HIV-infected than uninfected (0.19% ± 0.02% versus 0.43% ± 0.06%; p < 0.0001) men, and also lower in perinatally-infected than adolescence-infected men (0.15% ± 0.02% versus 0.22% ± 0.03%; p < 0.04). A higher proportion of COP cells correlated with higher bone stiffness, a measure of bone strength, whereas a higher proportion of activated CD4+ T cells correlated with lower BMD and stiffness and lower proportion of COP cells. T cell activation with HIV-infection was associated with decreased numbers of osteogenic precursors as well as lower peak bone mass and bone strength. © 2016 American Society for Bone and Mineral Research.

Immune activation and immune aging in HIV infection

PURPOSE OF REVIEW

The development of serious non-AIDS-related pathologies typically associated with aging, and the premature immune aging that characterizes HIV-1-infected patients, even with suppressive antiretroviral therapy, have raised increasing concerns in recent years. Deciphering the causes of these phenomena is key for our understanding of HIV pathogenesis and for the clinical care of patients living with the virus.

RECENT FINDINGS

An important basis for the immune parallels between HIV infection and aging lies in the exhaustion of the lymphopoietic capacity of infected individuals, which eventually affects all compartments of the immune system. The alleged cause for these immune alterations, and the onset of age-related comorbidities, is the systemic chronic immune activation that is established in patients. However, there is a multiplicity of contributors to this immune activation.

SUMMARY

Our understanding of the precise link between immune activation and aging in HIV infection is complicated by the influence of coinfections and life style factors. Developing rational interventions to reduce the hyper-inflammatory status of HIV-1-infected patients requires a clearer delineation of the factors contributing to the increased levels of systemic immune activation.

Premature aging and immune senescence in HIV-infected children

Supplemental Digital Content is available in the text

Several pieces of evidence indicate that HIV-infected adults undergo premature aging. The effect of HIV and antiretroviral therapy (ART) exposure on the aging process of HIV-infected children may be more deleterious since their immune system coevolves from birth with HIV.

CD4+/CD8+ ratio, age, and risk of serious noncommunicable diseases in HIV-infected adults on antiretroviral therapy

OBJECTIVE

In virologically suppressed HIV-infected adults, noncommunicable diseases (NCDs) have been associated with immune senescence and low CD4/CD8 lymphocyte ratio. Age differences in the relationship between CD4/CD8 ratio and NCDs have not been described.

DESIGN

Observational cohort study.

METHODS

We assessed CD4/CD8 ratio and incident NCDs (cardiovascular, cancer, liver, and renal diseases) in HIV-infected adults started on antiretroviral therapy between 1998 and 2012. Study inclusion began once patients maintained virologic suppression for 12 months (defined as baseline). We examined age and baseline CD4/CD8 ratio and used Cox proportional hazard models to assess baseline CD4/CD8 ratio and NCDs.

RESULTS

This study included 2006 patients. Low baseline CD4/CD8 ratio was associated with older age, male sex, and low CD4 lymphocyte counts. In models adjusting for CD4 lymphocyte count, CD4/CD8 ratio was inversely associated with age (P < 0.01). Among all patients, 182 had incident NCDs, including 46 with coronary artery disease (CAD) events. CD4/CD8 ratio was inversely associated with risk of CAD events [adjusted HR per 0.1 increase in CD4/CD8 ratio = 0.87, 95% confidence interval (CI): 0.76-0.99, P = 0.03]. This association was driven by those under age 50 years (adjusted HR 0.83 [0.70-0.97], P = 0.02) vs. those over age 50 years (adjusted HR = 0.96 [0.79-1.18], P = 0.71). CD4/CD8 ratio was not significantly associated with incident noncardiac NCDs.

CONCLUSIONS

Higher CD4/CD8 ratio after 1 year of HIV virologic suppression was independently predictive of decreased CAD risk, particularly among younger adults. Advanced immune senescence may contribute to CAD events in younger HIV patients on antiretroviral therapy.

Low thymic output, peripheral homeostasis deregulation, and hastened regulatory T cells differentiation in children with 22q11.2 deletion syndrome

OBJECTIVE

To perform an extensive analysis of the immune status of asymptomatic children with the 22q11.2 deletion syndrome, with special emphasis on the regulatory T cells (Treg) population.

STUDY DESIGN

Analysis of thymic function, frequency and absolute counts of immune subsets, and phenotype of Treg were performed in 10 asymptomatic children bearing the 22q11.2 deletion and compared with 12 age-matched, healthy children.

RESULTS

Children with 22q11.2 deletion syndrome showed a curtailed thymic output, lower T-cell levels, and a homeostatic deregulation in the CD4 T-cell compartment, characterized by a greater proliferative history in the naïve CD4 T-cell subset. Treg numbers were markedly reduced in children with 22q11.2 deletion syndrome, and remaining Treg showed mostly an activated phenotype.

CONCLUSIONS

Reduced thymic output in children with 22q11.2 deletion syndrome could be related with an increased proliferation in the naïve CD4 T-cell compartment and the consequent Treg activation to ensure that T-cell expansion remains under control. Deregulated peripheral homeostasis and loss of suppressive capacity by Treg could compromise the integrity of T-cell immunity during adulthood and play a relevant role in the increased incidence of autoimmune diseases reported in patients with the 22q11.2 deletion syndrome.

Subclinical atherosclerosis and markers of immune activation in HIV-infected children and adolescents: the CaroVIH Study

BACKGROUND

HIV-infected adults display increased cardiovascular disease, probably driven by inflammation and immune activation. These relationships have not been addressed in vertically HIV-infected children and adolescents, a population at very high risk for long-term non-AIDS complications.

METHODS

Carotid intima media thickness (IMT) was measured in a cohort of HIV-infected children and adolescents and healthy controls. C-reactive protein and markers of immune activation (CD38⁺HLA-DR⁺) and immune senescence (CD28⁻CD57⁺) were determined.

RESULTS

One hundred fifty HIV-infected patients and 150 controls were included, 64.8% female. IMT was thicker in HIV-infected patients (0.434 mm ± 0.025 vs. 0.424 mm ± 0.018, P < 0.001). After adjustment by age, sex, body mass index, and smoking status, HIV infection was independently associated with thicker IMT (odds ratio, 2.28; 95% confidence interval: 1.25 to 4.13; P = 0.007). Among HIV-related variables, a low CD4 nadir was related to an increased IMT. Although HIV-infected subjects presented higher frequencies of activated CD4⁺ and CD8⁺ T cells (P = 0.002 and P = 0.087, respectively), no relation was found between IMT and inflammation, immune activation, or senescence.

CONCLUSIONS

Structural changes of the vasculature present early in vertically HIV-infected subjects as well as immune activation and senescence. These patients should be carefully monitored for the prompt detection and early treatment of cardiovascular disease.