Relationship Between T-Cell Responses to CMV, Markers of Inflammation, and Frailty in HIV-uninfected and HIV-infected Men in the Multicenter AIDS Cohort Study

Cytomegalovirus serostatus among people with HIV, characterizing the prevalence, risk factors, and association with immune recovery

INTRODUCTION

Cytomegalovirus (CMV) infection is common among people with HIV (PWH), and may be associated with negative outcomes. We aimed to identify the seroprevalence of CMV between 01 January 1998 and 01 June 2022 among PWH accessing care at the Southern Alberta Clinic (SAC) and the associated risk factors. We also aimed to assess the impact of CMV seropositivity on CD4+ T-cells and CD4+/CD8+ ratio recovery among PWH who maintain HIV viral suppression.

METHODS

Poisson regression models with robust variance estimated crude and adjusted prevalence ratios and 95% confidence intervals to identify risk factors for CMV seronegativity. Among PWH maintaining viral suppression, trends in the median CD4+ T-cell count and CD4+/CD8+ ratio were visualized, and continuous time-to-event Cox proportional hazard models estimated hazards ratios (aHR) for CD4+ cell count recovery to ≥500 cells/mm3 and CD4+/CD8+ ratio of >1 at 10 years by CMV serostatus.

RESULTS

Among 3249 PWH, 2954 (91%) were CMV seropositive. CMV seronegativity was associated with younger ages, male sex, non-Hispanic white race and an education of ≥12 years. While CMV seronegativity did not affect CD4+ T-cell recovery following HIV viral suppression (aHR 1.15 [0.89-1.48]), it was associated with a greater likelihood of CD4+/CD8+ ratio normalization (aHR 2.38 [1.85-3.07]) at 10 years of follow-up.

CONCLUSIONS

CMV is a common coinfection among PWH. We found that CMV positivity among PWH maintaining HIV viral suppression, while not associated with CD4+ T-cell recovery, was associated with a reduced CD4+/CD8+ ratio recovery. This suggests an association with chronic CMV infection-mediated immune activation and inflammation among PWH.

Breadth and polyfunctionality of T cell responses to human cytomegalovirus in men who have sex with men: relationship with HIV infection and frailty

Cytomegalovirus (CMV)-seropositive adults have large T cell responses to a wide range of CMV proteins; these responses have been associated with chronic inflammation and frailty in people with or without HIV infection. We analyzed the relationships between chronic HIV infection, frailty, and the breadth and polyfunctionality of CD4 and CD8 T cell responses to CMV. Peripheral blood mononuclear cells from 42 men (20 without HIV and 22 with virologically suppressed HIV) in the Multicenter AIDS Cohort Study (MACS) were stimulated with peptide pools spanning 19 CMV open reading frames (ORFs). As measured by flow cytometry and intracellular cytokine staining for IFN-γ, TNF-α, and IL-2, CD8 T cells from men with HIV responded to significantly more CMV ORFs than those from men without HIV. This was primarily due to a broader response to ORFs that are expressed during the late phase of CMV replication. The number of ORFs to which a participant's T cells responded was positively correlated with the sum of all that individual's T cell responses; these correlations were weaker in men with than without HIV. Polyfunctional CMV-specific CD4 responses (production of more than one cytokine) were significantly lower in men with than without HIV. Frailty status did not substantially affect the breadth or magnitude of the CMV-specific T cell responses. These results suggest that immune control of CMV infection is affected more by chronic HIV infection than by frailty. The differences between men with and without HIV were similar to those reported between young and older adults without HIV.

IMPORTANCE

T cell responses to chronic cytomegalovirus (CMV) infection have significant biological and clinical implications in HIV infection and aging. Here, we systematically analyzed the breadth, magnitude, and polyfunctionality of T cell responses to multiple CMV antigens in men with and without HIV in the Multicenter AIDS Cohort Study (MACS), a longstanding study of the natural and treated history of HIV-1 infection in men who have sex with men. We found that the breadth and polyfunctionality of T cell responses to CMV were different between men with chronic, treated HIV and those without HIV. The reason for these differences is unknown, but these findings suggest that people with treated HIV may have more frequent CMV reactivation than people without HIV. Differences between people with and without HIV also resembled differences reported between young and older adults without HIV, supporting a role for the immune responses to CMV in the aging process.

Cytomegalovirus IgG is Associated With Physical Function But Not Muscle Density in People With HIV

BACKGROUND

Cytomegalovirus (CMV) seropositivity is associated with poor outcomes, including physical function impairment, in people without HIV. We examined associations between CMV IgG titer and physical function in virologically suppressed people with HIV (PWH).

METHODS

REPRIEVE is a double-blind randomized trial evaluating pitavastatin for primary prevention of atherosclerotic cardiovascular disease in PWH. This analysis focused on participants enrolled in a substudy with additional biomarker testing, imaging [coronary CT angiography], and physical function measures at entry. CMV IgG was measured using quantitative enzyme immunoassay, physical function by Short Physical Performance Battery, and muscle density and area by CT. Associations between CMV IgG (risk factor) and outcomes were evaluated using the partial Spearman correlation and linear and log-binomial regression.

RESULTS

Among 717 participants, 82% male, the median CMV IgG was 2716 (Q1, Q3: 807, 6672) IU/mL, all above the limit of quantification. Among 631 participants with imaging, there was no association between CMV IgG and CT-based muscle density or area, controlling for age (r = -0.03 and r = -0.01, respectively; P ≥ 0.38). Among 161 participants with physical function data, higher CMV IgG was associated with poorer overall modified Short Physical Performance Battery score ( P = 0.02), adjusted for age, nadir CD4, and high-sensitivity C-reactive protein.

CONCLUSIONS

Higher CMV IgG titer was associated with poorer physical function, not explained by previous immune compromise, inflammation, or muscle density or area. Further mechanistic studies are needed to understand this association and whether CMV-specific therapy can affect physical function in PWH.

Evolving mechanisms and presentations of cardiovascular disease in people with HIV: implications for management

People with HIV (PWH) are at elevated risk for cardiovascular diseases (CVDs), including myocardial infarction, heart failure, and sudden cardiac death, among other CVD manifestations. Chronic immune dysregulation resulting in persistent inflammation is common among PWH, particularly those with sustained viremia and impaired CD4+ T cell recovery. This inflammatory milieu is a major contributor to CVDs among PWH, in concert with common comorbidities (such as dyslipidemia and smoking) and, to a lesser extent, off-target effects of antiretroviral therapy. In this review, we discuss the clinical and mechanistic evidence surrounding heightened CVD risks among PWH, implications for specific CVD manifestations, and practical guidance for management in the setting of evolving data.

Immune profiles of pre-frail people living with HIV-1: a prospective longitudinal study

BACKGROUND

People living with HIV (PLWH) are at risk of frailty, which is predictive for death. As an overactivity of the immune system is thought to fuel frailty, we characterized the immune activation profiles linked to frailty.

METHODS

We quantified twenty-seven activation markers in forty-six virological responders (four females and forty-two males; median age, 74 years; median duration of infection, 24 years; median duration of undetectability, 13 years), whose frailty was determined according to the Fried criteria. T cell and NK cell activation was evaluated by flow cytometry, using a panel of cell surface markers. Soluble markers of inflammation, and monocyte activation and endothelial activation were measured by ELISA. The participants' immune activation was profiled by an unsupervised double hierarchical clustering analysis. We used ANOVA p-values to rank immunomarkers most related to Fried score. A Linear Discriminant Analysis (LDA) was performed to link immune activation markers to frailty.

RESULTS

41% of the participants were pre-frail, including 24% with a Fried score of 1, and 17% with a Fried score of 2. ANOVA identified the 14 markers of T cell, monocyte, NK cell, endothelial activation, and inflammation the most linked to Fried 3 classes. The LDA performed with these 14 markers was capable of discriminating volunteers according to their Fried score. Two out of the 5 immune activation profiles revealed by the hierarchical clustering were linked to and predictive of pre-frailty. These two profiles were characterized by a low percentage of CD4 T cells and a high percentage of CD8 T cells, activated CD4 T cells, CD8 T cells, and NK cells, and inflammation.

CONCLUSIONS

We identified a particular immune activation profile associated with pre-frailty in PLWH. Profiling participants at risk of developing frailty might help to tailor the screening and prevention of medical complications fueled by loss of robustness. Further studies will indicate whether this frailty signature is specific or not of HIV infection, and whether it also precedes frailty in the general population.

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.

Association between frailty phenotype, quantification of plasma HIV-1 RNA, CD4 cell count and HAART in HIV-positive subjects: a systematic review and meta-analysis of observational studies

HIV infection causes a constant activation of the immune system and contributes to an enhanced systemic pro-inflammatory cytokine milieu, which has been associated with premature aging and frailty. We performed a systematic review and meta-analysis to analyze whether the HIV-1 RNA load, CD4+ T-lymphocyte counts and exposure to HAART in HIV-positive subjects are associated with frailty phenotype. Searches were performed in PubMed, SCOPUS, Lilacs, Web of Science, Google Scholar, and OpenThesis databases. We used the odds ratio as a measure of the association. We used either a fixed or random-effects model to pool the results of individual studies depending on the presence of heterogeneity. Eleven studies were included in the review. Data from 8035 HIV-positive subjects were analyzed; 2413 of the subjects had viral load detectable, 981 had a CD4T-cell count <350 cells/μL, and 1342 had HAART exposure information. We found an association between frailty and CD4T-cell count <350 cells/μL (OR 2.68, CI 95% 1.68-4.26, I²= 46%), HIV-1 RNA load detectable (OR 1.71, CI 95% 1.38-2.12, I²= 0%), and protease inhibitor-containing HAART regimen (OR 2.21, CI 95% 1.26-3.89, I² = 0%). Further studies are necessary to evaluate the effects of other factors on the development of clinical features related to frailty.

Inflammatory and immune markers in HIV-infected older adults on long-term antiretroviral therapy: Persistent elevation of sCD14 and of proinflammatory effector memory T cells

HIV-positive patients whose viral loads are successfully controlled by active antiretroviral therapy (ART) show no clinical signs of AIDS. However, their lifespan is shorter compared with individuals with no HIV infection and they prematurely exhibit a multitude of chronic diseases typically associated with advanced age. It was hypothesized that immune system aging may correlate with, and provide useful biomarkers for, this premature loss of healthspan in HIV-positive subjects. Here, we tested whether the immune correlates of aging, including cell numbers and phenotypes, inflammatory status, and control of human cytomegalovirus (hCMV) in HIV-positive subjects on long-term successful ART (HIV+) may reveal increased "immunological age" compared with HIV-negative, age-matched cohort (HIV-) in participants between 50 and 69 years of age. Specifically, we expected that younger HIV+ subjects may immunologically resemble older individuals without HIV. We found no evidence to support this hypothesis. While T cells from HIV+ participants displayed differential expression in several differentiation and/or inhibitory/exhaustion markers in different T cell subpopulations, aging by a decade did not pronounce these changes. Similarly, while the HIV+ participants exhibited higher T cell responses and elevated inflammatory marker levels in plasma, indicative of chronic inflammation, this trait was not age-sensitive. We did find differences in immune control of hCMV, and, more importantly, a sustained elevation of sCD14 and of proinflammatory CD4 and CD8 T cell responses across age groups, pointing towards uncontrolled inflammation as a factor in reduced healthspan in successfully treated older HIV+ patients.

Longitudinal association of cytokine-producing CMV-specific T cells with frailty in HIV-infected and -uninfected men who have sex with men

BACKGROUND

Chronic cytomegalovirus (CMV) infection has been postulated as a driver of chronic inflammation that has been associated with frailty and other age-related conditions in both HIV-infected (HIV+) and -uninfected (HIV-) people.

METHODS

To study the T cell response to CMV as a predictor of onset and maintenance of frailty, baseline CMV-specific T cell responses of 42 men (20 HIV-, 22 HIV+; 21 frail, 21 nonfrail) in the Multicenter AIDS Cohort Study (MACS) were assessed by flow cytometric analysis of cytokine production (IFN-γ, TNF-⍺, and IL-2) in response to overlapping peptide pools spanning 19 CMV open reading frames. The Fried frailty phenotype was assessed at baseline and semiannually thereafter. Times to transition into or out of frailty were compared by tertiles of percentages of cytokine-producing T cells using Kaplan-Meier estimators and the exact log-rank test.

RESULTS

Over a median follow-up of 6.5 (interquartile range: 2) years, faster onset of frailty was significantly predicted by higher (HIV- men) or lower (HIV+ men) percentages of CD4 T cells producing only IFN-γ (IFN-γ-single-producing (SP)), and by lower percentages of IFN-γ-, TNF-⍺-, and IL-2-triple-producing CD8 T cells (HIV- men). Greater maintenance of frailty was significantly predicted by lower percentages of both these T cell subsets in HIV- men, and by lower percentages of IFN-γ-SP CD4 T cells in HIV+ men. The antigenic specificity of IFN-γ-SP CD4 T cells was different between HIV- and HIV+ nonfrail men, as were the correlations between these cells and serum inflammatory markers.

CONCLUSIONS

In this pilot study, percentages of CMV-specific T cells predicted the onset and maintenance of frailty in HIV- and HIV+ men. Predictive responses differed by HIV status, which may relate to differential control of CMV reactivation and inflammation by anti-CMV T cell responses.

HIV-Related Immune Activation and Inflammation: Current Understanding and Strategies

Although antiretroviral therapy effectively controls human immunodeficiency virus (HIV) replication, a residual chronic immune activation/inflammation persists throughout the disease. This aberrant immune activation and inflammation are considered an accelerator of non-AIDS-related events and one of the driving forces of CD4⁺ T cell depletion. Unfortunately, HIV-associated immune activation is driven by various factors, while the mechanism of excessive inflammation has not been formally clarified. To date, several clinical interventions or treatment candidates undergoing clinical trials have been proposed to combat this systemic immune activation/inflammation. However, these strategies revealed limited results, or their nonspecific anti-inflammatory properties are similar to previous interventions. Here, we reviewed recent learnings of immune activation and persisting inflammation associated with HIV infection, as well as the current directions to overcome it. Of note, a more profound understanding of the specific mechanisms for aberrant inflammation is still imperative for identifying an effective clinical intervention strategy.

Senotherapeutics for HIV and aging

PURPOSE OF REVIEW

To summarize the state of chronic, treated HIV infection and its contribution to accelerated aging, and to evaluate recent research relevant to the study and treatment of aging and senescence.

RECENT FINDINGS

Chronic treated HIV-1 infection is associated with significant risk of end-organ impairment, non-AIDS-associated malignancies, and accelerated physiologic aging. Coupled with the chronologic aging of the HIV-1-positive population, the development of therapies that target these processes is of great clinical importance. Age-related diseases are partly the result of cellular senescence. Both immune and nonimmune cell subsets are thought to mediate this senescent phenotype, a state of stable cell cycle arrest characterized by sustained release of pro-inflammatory mediators. Recent research in the field of aging has identified a number of 'senotherapeutics' to combat aging-related diseases, pharmacologic agents that act either by selectively promoting the death of senescent cells ('senolytics') or modifying senescent phenotype ('senomorphics').

SUMMARY

Senescence is a hallmark of aging-related diseases that is characterized by stable cell cycle arrest and chronic inflammation. Chronic HIV-1 infection predisposes patients to aging-related illnesses and is similarly marked by a senescence-like phenotype. A better understanding of the role of HIV-1 in aging will inform the development of therapeutics aimed at eliminating senescent cells that drive accelerated physiologic aging.

Frailty: the current challenge for aging people with HIV

PURPOSE OF REVIEW

Older adults account for the majority of people with HIV (PWH) in high-income countries and have increasingly complex clinical profiles related to premature aging. Frailty is an important geriatric syndrome affecting a minority of PHW. Frailty negatively affects PHW's clinical status and quality of life. This review will update care providers on the current state of frailty that limits the healthspan of PWH.

RECENT FINDINGS

Ongoing low-level HIV replication in treated PWH leads to immune activation and chronic inflammation contributing to the destabilization of normally autoregulated physiologic systems in response to environmental and biologic challenges characteristic of frailty. Understanding these underlying mechanisms will determine potential intervention options. Potentially reversible risk factors that promote progression to and reversion from the dynamic state of frailty are being studied and will help prevent frailty. Simple assessment tools and treatment strategies for frailty are being adapted for aging PWH.

SUMMARY

Insight into underlying biologic mechanisms and adapting proven geriatric principles of interdisciplinary care will inform the healthy aging of PWH.

Clinical consequences of asymptomatic cytomegalovirus in treated human immunodeficency virus infection

PURPOSE OF REVIEW

Despite antiretroviral therapy (ART)-mediated viral suppression, people with human immunodeficiency virus (HIV) (PWH) have increased morbidity and mortality. Immune activation and inflammation persist on ART and predict these complications. Over 90% of PWH have cytomegalovirus (CMV) co-infection, and CMV is considered a plausible contributor to this persistent immune activation.

RECENT FINDINGS

A detailed understanding of the link between CMV and multimorbidity is needed, particularly as research moves toward identifying potential targeted therapeutics to attenuate inflammation-mediated morbidity and mortality in treated HIV. We review the literature on the association between CMV and immune activation as well as multiple end-organ complications including cardiovascular disease, venous thromboembolic disease, metabolic complications, gastrointestinal dysfunction, central nervous system involvement, birth sex-related differences, and the relation to the HIV reservoir. We conclude with a discussion of ongoing therapeutic efforts to target CMV.

SUMMARY

As CMV is a plausible driver of multiple comorbidities through persistent immune activation in treated HIV, future research is needed and planned to address its causal role as well as to test novel therapeutics in this setting.

Descriptive modification of inflammatory markers in HIV patients after cART initiation according to gender, smoking habit, CMV infection, BMI and serum lipids

Persistent inflammation, despite anti-retroviral therapy (ART), is an independent predictor of mortality and comorbidities in HIV infection. Multiple factors, including lifestyle and chronic viral coinfections, may contribute. Several of these factors are also associated with a chronic inflammation in the general population. Little is known about the degree to which these factors influence inflammation in HIV infection, particularly within the first year of ART. The purpose of this study was to distinguish the effects of factors (gender, body mass index, cholesterol and triglyceride levels, smoke habit and cytomegalovirus seropositivity), known to contribute to inflammation, on inflammation biomarkers over the first year of ART in HIV-infected patients. Linear mixed model analysis revealed significant biomarker decreases [soluble CD14 (s-CD14), soluble CD163 (s-CD163) and D-dimer (DD)], or increases [C Reactive Protein (CRP) and interleukin-6 (IL-6)] over time in the whole cohort, differences in most categories (genders for IL-6, smoke habit for s-CD14, cytomegalovirus infection for s-CD163 and IL-6) and in some category × time interactions [gender for interleukin-7 (IL-7)], cytomegalovirus infection for s-CD14 and cholesterol levels for s-CD14 and Tumor Necrosis Factor α (TNF-α)]. This explorative longitudinal study suggests further investigations on targeting inflammation pathophysiology in HIV-infected patients on ART.

Validation of Preamplification to Improve Quantification of Cytomegalovirus DNA Using Droplet Digital Polymerase Chain Reaction

Subclinical cytomegalovirus (CMV) replication is associated with strong cellular immune response and chronic inflammation, which could contribute to aging-related conditions such as cardiovascular disease and frailty. However, because of very low levels of CMV DNA present in people with chronic CMV infection, it has been difficult to explore the virologic and immunologic mechanisms of chronic low-level CMV infection and a sensitive method to monitor CMV replication is needed. Droplet digital PCR (ddPCR) has been shown to have higher precision and reproducibility than real-time quantitative PCR (qPCR) in quantifying low levels of CMV DNA, but it is not always sensitive enough for this purpose. Through rigorous validation experiments, we demonstrated that sensitivity and precision of quantification of very low levels of CMV DNA by ddPCR can be significantly increased by preamplification of samples with 10-20 cycles of conventional PCR, especially when testing CMV DNA in the presence of cellular DNA. With preamplification, we could reliably quantify down to two copies of CMV DNA, as opposed to five copies without preamplification. Further studies are needed to determine if ddPCR with preamplification can facilitate mechanistic studies of the characteristics and consequences of chronic CMV infection in aging adults.

Frailty in People Living with HIV

PURPOSE OF REVIEW

Different factors contribute to the decreased overall long-term survival in treated people living with HIV (PLWH). This paper will review the state of physical frailty which limits successful aging in PLWH.

RECENT FINDINGS

Identifiable events on the continuum from clinical normality to heightened risk of adverse health outcomes contribute to frailty. These center on chronic inflammation leading to destabilization of autoregulated physiologic systems challenged by environmental and biologic challenges. Frailty assessment can inform the profile of aging PLWH at increased risk of common age-related disorders and geriatric syndromes. Biologic and psychosocial risk factors promoting progression to and reversion from a dynamic state of frailty are being investigated, allowing for preventative interventions to be considered. Insights gained from studying frail PLWH will help adapt an interdisciplinary geriatric model of health care for selected PLWH. This will improve the health and well-being of aging PLWH.

Pathogenesis of Aging and Age-related Comorbidities in People with HIV: Highlights from the HIV ACTION Workshop

People with HIV (PWH) experience accentuated biological aging, as defined by markers of inflammation, immune dysfunction, and the epigenetic clock. They also have an elevated risk of multiple age-associated comorbidities. To discuss current knowledge, research gaps, and priorities in aging and age-related comorbidities in treated HIV infection, the NIH program staff organized a workshop held in Bethesda, Maryland in September 2019. This review article describes highlights of discussions led by the Pathogenesis/Basic Science Research working group that focused on three high priority topics: immunopathogenesis; the microbiome/virome; and aging and senescence. We summarize knowledge in these fields and describe key questions for research on the pathogenesis of aging and age-related comorbidities in PWH. Understanding the drivers and mechanisms underlying accentuated biological aging is a high priority that will help identify potential therapeutic targets to improve healthspan in older PWH.

Understanding the mechanism of action of cytomegalovirus-induced regulatory T cells

We previously showed that CMV-induced CD4⁺CD27^-CD28^- T cells have regulatory (Treg) function. Here we sought to identify the target/s and the mechanistic underpinning/s of this effect. CMV-induced CD4⁺CD27^-CD28^-were sorted from CMV-stimulated PBMC and added to CMV-stimulated autologous PBMC cultures. Transwell experiments showed that the CMV-induced Treg mechanism of action required cell-to-cell contact. CMV-Treg significantly decreased proliferation of autologous CMV-stimulated CD8⁺ and, to a lesser extent, CD4⁺ T cells; reduced activation and increased apoptosis of CD4⁺ and CD8⁺ T cells; and increased apoptosis and expression of CTLA-4, T cell-inhibitory ligand, on dendritic cells. There was no effect on monocytes. Anti-PD-1, but not anti-CTLA-4, mAb-treatment increased proliferation of CD8⁺ T cells and decreased apoptosis of CD4⁺ and CD8⁺ T cells. Our data indicated that CD8⁺ T cells were the main target of CMV-specific Treg, which induced apoptosis of their targets using the PD-1 pathway.

Chronic comorbidities in children and adolescents with perinatally acquired HIV infection in sub-Saharan Africa in the era of antiretroviral therapy

Globally, 1·7 million children are living with HIV, of which 90% are in sub-Saharan Africa. The remarkable scale-up of combination antiretroviral therapy has resulted in increasing numbers of children with HIV surviving to adolescence. Unfortunately, in sub-Saharan Africa, HIV diagnosis is often delayed with children starting antiretroviral therapy late in childhood. There have been increasing reports from low-income settings of children with HIV who have multisystem chronic comorbidities despite antiretroviral therapy. Many of these chronic conditions show clinical phenotypes distinct from those in adults with HIV, and result in disability and reduced quality of life. In this Review, we discuss the spectrum and pathogenesis of comorbidities in children with HIV in sub-Saharan Africa. Prompt diagnosis and treatment of perinatally acquired HIV infection is a priority. Additionally, there is a need for increased awareness of the burden of chronic comorbidities. Diagnostic and therapeutic strategies need to be collectively developed if children with HIV are to achieve their full potential.

Advances in cytomegalovirus (CMV) biology and its relationship to health, diseases, and aging

Cytomegalovirus (CMV) is one of the largest and most ubiquitous latent persistent viruses. Most humans are infected with CMV early in life, and all immunocompetent humans spend several decades living with CMV. In the vast majority of the hosts, CMV does not cause manifest disease, and CMV therefore can be considered part of normal aging for 50–90% of the human population worldwide. Experimental, clinical, and epidemiological studies suggest that CMV carriage can have nuanced outcomes, including both potentially harmful and potentially beneficial impacts on the host. We here present a summary of the 7th International Workshop on CMV and Immunosenescence, covering various aspects of the interplay between CMV and its mammalian hosts in the context of virus spread, immune evasion, antiviral immunity, as well as the impact on health span and aging.

Tfh cell subset biomarkers and inflammatory markers are associated with frailty status and frailty subtypes in the community-dwelling older population: a cross-sectional study

We conducted a cross-sectional study investigating community-dwelling older population to determine association between immunoscenescence marker, inflammatory cytokines and frailty. Frailty status was classified with 33-item modified frailty index and latent class analysis was applied to explore the latent classes (subtypes) of frailty. In multivariable analysis, higher Tfh2 cells were associated with a higher risk of frailty [1.13(1.03–1.25)] in females, but a lower risk of cognitive and functional frail [0.92(0.86–0.99)] and physiological frail [0.92(0.87–0.98)]. Additionally, a greater risk of multi-frail and physiological frail correlated with low Tfh1 [0.77(0.60–0.99); 0.87(0.79–0.96)] and Tfh17 cells [0.79(0.65–0.96); 0.86(0.78–0.94)], respectively. Higher B cells were associated with decreased frailty/pre-frailty both in females [0.89(0.81–0.98)] and males [0.82(0.71–0.96)], but did not correlate with frailty subtypes. Regarding inflammatory markers, participants in the TGF-β 2^nd quartile showed a decreased risk of pre-frailty/frailty in females [0.39(0.17–0.89)] and psychological frail [0.37(0.16–0.88)], compared with those in the top tertile. Moreover, we found participants in the 2^nd tertile for IL-12 levels showed a decreased risk of physiological frail [0.40 (0.17–0.97)]. Our study highlights the importance of Tfh cell subsets and inflammatory markers in frailty in a sex-specific manner, particularly in terms of frailty subtype.

Aging, sex, inflammation, frailty, and CMV and HIV infections

Aging is characterized by significant immune remodeling at both cellular and molecular levels, also known as immunosenescence. Older adults often manifest a chronic low-grade inflammatory phenotype. These age-related immune system changes have increasingly been recognized not only to lead to immune functional decline and increased vulnerability to infections, but also to play an important role in many chronic conditions such as frailty in older adults. In addition to sex as an important biological factor, chronic viral infections including that by human immunodeficiency virus (HIV) and cytomegalovirus (CMV) are all known to have major impact on the aging immune system. This article provides an overview of our current understanding of aging immunity, sex, inflammation, frailty, and HIV and CMV infections.

HIV-negative Men Who Have Sex with Men have higher CD8+ T-cell Counts and Lower CD4+/CD8+ T-cell Ratios compared to HIV-negative Heterosexual Men

Background

We previously reported T-cell senescence to be similar in people with human immunodeficiency virus (PWH) with suppressed viremia (predominantly men who have sex with men [MSM]) and human immunodeficiency virus (HIV)-negative otherwise comparable controls but greater than in healthy blood donors. This led us to compare CD4⁺ and CD8⁺ T-cell counts and CD4⁺/CD8⁺ ratios between HIV-negative MSM and men who only have sex with women (MSW) and relate observed differences in behavioral factors and infectious exposures, including cytomegalovirus (CMV) infection.

Methods

In 368 HIV-negative MSM and 72 HIV-negative MSW, T lymphocyte phenotyping was performed 3 times biennially. Baseline CMV serology and sexually transmitted infection (STI) incidence and/or STI seroprevalence, sexual, and substance-use behavior data were collected during study visits.

Results

Men who have sex with men, compared with MSW, had higher CD8⁺ counts (551 vs 437 cells/mm³, P < .001), similar CD4⁺ counts (864 vs 880 cells/mm³, P = .5), and lower CD4⁺/CD8⁺ ratios (1.84 vs 2.47, P < .001). Differences were most pronounced for MSM with >10 recent sex partners and partly explained by higher CMV seroprevalence in MSM.

Conclusions

These findings suggest that factors other than HIV may, in both PWH and certain HIV-negative MSM, contribute to a low CD4⁺/CD8⁺ ratio. Whether this, like in PWH, contributes to comorbidity risk in HIV-negative MSM requires further study.

Systemic Inflammation and the Increased Risk of Inflamm-Aging and Age-Associated Diseases in People Living With HIV on Long Term Suppressive Antiretroviral Therapy

The ART program in low- and middle-income countries (LMIC) like India, follows a public health approach with a standardized regimen for all people living with HIV (PLHIV). Based on the evidence from high-income countries (HIC), the risk of an enhanced, and accentuated onset of premature-aging or age-related diseases has been observed in PLHIV. However, very limited data is available on residual inflammation and immune activation in the populations who are on first-generation anti-HIV drugs like zidovudine and lamivudine that have more toxic side effects. Therefore, the aim of the present study was to evaluate the levels of systemic inflammation and understand the risk of age-associated diseases in PLHIV on long-term suppressive ART using a large number of biomarkers of inflammation and immune activation. Blood samples were obtained from therapy naïve PLHIV (Pre-ART, n = 43), PLHIV on ART for >5 years (ART, n = 53), and HIV-negative healthy controls (HIVNC, n = 41). Samples were analyzed for 92 markers of inflammation, sCD14, sCD163, and telomere length. Several statistical tests were performed to compare the groups under study. Multivariate linear regression was used to investigate the associations. Despite a median duration of 8 years of successful ART, sCD14 (p < 0.001) and sCD163 (p = 0.04) levels continued to be significantly elevated in ART group as compared to HIVNC. Eleven inflammatory markers, including 4E-BP1, ADA, CCL23, CD5, CD8A, CST5, MMP1, NT3, SLAMF1, TRAIL, and TRANCE, were found to be significantly different (p < 0.05) between the groups. Many of these markers are associated with age-related co-morbidities including cardiovascular disease, neurocognitive decline and some of these markers are being reported for the first time in the context of HIV-induced inflammation. Linear regression analysis showed a significant negative association between HIV-1-positivity and telomere length (p < 0.0001). In ART-group CXCL1 (p = 0.048) and TGF-α (p = 0.026) showed a significant association with the increased telomere length and IL-10RA was significantly associated with decreased telomere length (p = 0.042). This observation warrants further mechanistic studies to generate evidence to highlight the need for enhanced treatment monitoring and special interventions in HIV-infected individuals.

HIV-Related Arterial Stiffness in Malawian Adults Is Associated With the Proportion of PD-1-Expressing CD8+ T Cells and Reverses With Antiretroviral Therapy

BACKGROUND

The contribution of immune activation to arterial stiffness and its reversibility in human immunodeficiency virus (HIV)-infected adults in sub-Saharan Africa is unknown.

METHODS

HIV-uninfected and HIV-infected Malawian adults initiating antiretroviral therapy (ART) with a CD4+ T-cell count of <100 cells/μL were enrolled and followed for 44 weeks; enrollment of infected adults occurred 2 weeks after ART initiation. We evaluated the relationship between carotid femoral pulse wave velocity (cfPWV) and T-cell activation (defined as HLA-DR+CD38+ T cells), exhaustion (define as PD-1+ T cells), and senescence (defined as CD57+ T cells) and monocyte subsets, using normal regression.

RESULTS

In 279 HIV-infected and 110 HIV-uninfected adults, 142 (37%) had hypertension. HIV was independently associated with a 12% higher cfPWV (P = .02) at baseline and a 14% higher cfPWV at week 10 (P = .02), but the increases resolved by week 22. CD4+ and CD8+ T-cell exhaustion were independently associated with a higher cfPWV at baseline (P = .02). At 44 weeks, arterial stiffness improved more in those with greater decreases in the percentage of CD8+ T cells and the percentage of PD-1+CD8+ T cells (P = .01 and P = .03, respectively). When considering HIV-infected participants alone, the adjusted arterial stiffness at week 44 tended to be lower in those with higher baseline percentage of PD-1+CD8+ T cells (P = .054).

CONCLUSIONS

PD-1+CD8+ T-cells are associated with HIV-related arterial stiffness, which remains elevated during the first 3 months of ART. Resources to prevent cardiovascular disease in sub-Saharan Africa should focus on blood pressure reduction and individuals with a low CD4+ T-cell count during early ART.

T-cell immunity against cytomegalovirus in HIV infection and aging: relationships with inflammation, immune activation, and frailty

Both aging and treated human immunodeficiency virus (HIV) infection are characterized by low-level chronic inflammation and immune activation which contribute to the development of age-related diseases, frailty, and early mortality. Chronic cytomegalovirus (CMV) infection is highly prevalent in older adults and HIV-infected populations. A number of studies have shown that CMV induces broad and strong T-cell responses in CMV-seropositive older adults and HIV-infected individuals. CMV infection rarely develops into clinical disease in immunocompetent individuals. However, a large body of literature has shown adverse effects of chronic CMV infection on the health and longevity of these populations. It has been hypothesized that chronic CMV infection may be a driver of chronic inflammation and immune activation, and may further contribute to the development of frailty. Thus, there is a need to better understand the extent of the impact of chronic CMV infection on T-cell immunity and health in aging and HIV infection. In this review, we will address important considerations and challenges in the assessment of chronic CMV infection and CMV-specific T-cell responses. We will then review recent data on relationships between T-cell responses to CMV and levels of inflammatory markers and immune activation, as well as the onset of frailty.

Chronic Low-grade Inflammatory Phenotype (CLIP) and Senescent Immune Dysregulation

PURPOSE

The aim was to provide an overview of chronic low-grade inflammatory phenotype (CLIP) and evidence for its role in the pathogenesis of frailty and other chronic conditions as well as potential causative factors and interventions.

METHODS

We reviewed evidence from published clinical and laboratory studies and summarized the opinions of experts from published reviews.

FINDINGS

CLIP is a low-grade, systemic, unresolved, and smoldering chronic inflammatory state clearly indicated by a 2- to 4-fold increase in serum levels of inflammatory mediators, such as interleukin-6 and C-reactive protein. It involves many other cellular and molecular inflammatory mediators. CLIP typically occurs during aging, also known as "inflammaging," and is an integral part of the spectrum of immunosenescence. Causative factors likely include persistent viral infections, particularly chronic cytomegalovirus infection, cellular senescence, failure to eliminate degraded materials and waste products, dysregulated microbiota and gut permeability, obesity, and others. Substantial evidence supports CLIP as a powerful contributing factor to frailty and many other chronic conditions and adverse health outcomes. Many of the inflammatory mediators and their regulatory mechanisms in CLIP may serve as potential targets for therapeutic intervention. However, development of new interventional strategies for CLIP and its associated chronic conditions should take the complexity of the inflammatory network into consideration. Nonpharmacologic interventions, such as caloric restriction and exercise, may have significant impact on CLIP and its causative factors, leading to substantial health benefits. Metformin and resveratrol have anti-inflammatory property and may serve as a promising therapeutic agent for treatment of CLIP and frailty.

IMPLICATIONS

CLIP is a chronic inflammatory pathophysiologic process that plays an important role in the pathogenesis of frailty and many other chronic conditions. Improving our understanding of this phenotype may provide opportunities to identify potential targets of effective prevention and therapeutic strategies for frailty and other CLIP-associated conditions.