Telomere Length as an Indicator of the Robustness of B- and T-Cell Response to Influenza in Older Adults

No correlative evidence of costs of infection or immunity on leucocyte telomere length in a wild population of Soay sheep

Telomere length (TL) is a biomarker hypothesized to capture evolutionarily and ecologically important physiological costs of reproduction, infection and immunity. Few studies have estimated the relationships among infection status, immunity, TL and fitness in natural systems. The hypothesis that short telomeres predict reduced survival because they reflect costly consequences of infection and immune investment remains largely untested. Using longitudinal data from a free-living Soay sheep population, we tested whether leucocyte TL was predicted by infection with nematode parasites and antibody levels against those parasites. Helminth parasite burdens were positively associated with leucocyte TL in both lambs and adults, which is not consistent with TL reflecting infection costs. We found no association between TL and helminth-specific IgG levels in either young or old individuals which suggests TL does not reflect costs of an activated immune response or immunosenescence. Furthermore, we found no support for TL acting as a mediator of trade-offs between infection, immunity and subsequent survival in the wild. Our results suggest that while variation in TL could reflect short-term variation in resource investment or environmental conditions, it does not capture costs of infection and immunity, nor does it behave like a marker of an individual's helminth-specific antibody immune response.

Efficacy of a dietary supplement derived from five edible plants on telomere length in Thai adults: A randomized, double-blind, placebo-controlled trial

Mylife/Mylife100® is a dietary supplement consisting of black sesame seed, guava fruit, mangosteen aril, pennywort leaves, and soy protein. These edible plants contain multiple high-potential bioactive compounds exerting various vital biological functions including antioxidants which contribute to delaying the rate of telomere shortening. Telomere length is associated with cellular aging and age-related diseases. This study aimed to assess the efficacy of Mylife/Mylife100® on telomere length through a randomized, double-blind placebo-controlled trial. The trial assessed the alteration of leukocyte telomere length after 32 adults aged 50-65 years received either Mylife/Mylife100® or placebo (five capsules/day) for 8-week supplementation. The results demonstrated a significant increase in mean telomere length from baseline (6313 bp) to the 8-week supplementation period (6655 bp; p < 0.05) in the group receiving the product, whereas no significant change was observed in the placebo group. Additionally, the product group exhibited a significant improvement in plasma total antioxidant capacity levels compared to the placebo group (mean change, +35 vs -38; p = 0.006). This study also showed a significant correlation between telomere length and % CD4 + T cells (r = +0.325; p = 0.00003), % CD8 + T cells (r = +0.156; p = 0.048), and visceral fat (r = - 0.349; p = 0.000006). The findings suggest that consuming this dietary supplement (Mylife/Mylife100®) for 8 weeks has a positive effect on cellular aging by lengthening telomeres possible through their antioxidant capacities. Oxidative stress and cellular aging are underlying predisease mechanisms that might be alleviated by supplementing with this product.

Genomic Instability Evolutionary Footprints on Human Health: Driving Forces or Side Effects?

In this work, we propose a comprehensive perspective on genomic instability comprising not only the accumulation of mutations but also telomeric shortening, epigenetic alterations and other mechanisms that could contribute to genomic information conservation or corruption. First, we present mechanisms playing a role in genomic instability across the kingdoms of life. Then, we explore the impact of genomic instability on the human being across its evolutionary history and on present-day human health, with a particular focus on aging and complex disorders. Finally, we discuss the role of non-coding RNAs, highlighting future approaches for a better living and an expanded healthy lifespan.

Transcriptome-based measurement of CD8+ T cell age and its applications

The ability of T cells to undergo robust cell division in response to antigenic stimulation is essential for competent T cell function. However, this ability is reduced with aging and contributes to increased susceptibility to infectious diseases, cancers, and other diseases among older adults. To better understand T cell aging, improved measurements of age-related cellular changes in T cells are necessary. The recent development of machine learning (ML)-assisted transcriptome-based quantification of individual CD8+ T cell age represents a significant step forward in this regard. It reveals both prominent and subtle changes in gene expression and points to potential functional alterations of CD8+ T cells with aging. I argue that single-cell transcriptome-based age prediction in the immune system may have promising future applications.

Assessing the association of leukocyte telomere length with ankylosing spondylitis and rheumatoid arthritis: A bidirectional Mendelian randomization study

Background

Telomere length shortening can cause senescence and apoptosis in various immune cells, resulting in immune destabilization and ageing of the organism. In this study, we aimed to systematically assess the causal relationship of leukocyte telomere length (LTL) with ankylosing spondylitis (AS) and rheumatoid arthritis (RA) using a Mendelian randomization study.

Methods

LTL (n=472174) was obtained from the UK Biobank genome-wide association study pooled data. AS (n=229640), RA (n=212472) were obtained from FinnGen database. MR-Egger, inverse variance weighting, and weighted median methods were used to estimate the effects of causes. Cochran's Q test, MR Egger intercept test, MR-PRESSO, leave-one-out analysis, and funnel plots were used to look at sensitivity, heterogeneity, and multiple effects. Forward MR analysis considered LTL as the exposure and AS, RA as the outcome. Reverse MR analysis considered AS, RA as the exposure and LTL as the outcome.

Results

In the forward MR analysis, inverse variance-weighted and weighted median analysis results indicated that longer LTL might be associated with increased risk of AS (IVW: OR = 1.55, 95% CI: 1.14-2.11, p = 0.006). MR Egger regression analysis showed no pleiotropy between instrumental variables (IVs) (Egger intercept= 0.008, p = 0.294). The leave-one-out analysis showed that each single nucleotide polymorphism (SNP) of AS was robust to each outcome. No significant causal effects were found between AS, RA and LTL in the reverse MR analysis.

Conclusion

Longer LTL may be related with an increased risk of developing AS, and these findings provide a foundation for future clinical research on the causal association between LTL and AS.

Association of weight range with telomere length: A retrospective cohort study

Objective

Previous research has shown a significant association between weight and telomere length, but did not take into consideration weight range. The study was to investigate the association of weight range with telomere length.

Methods

Data of 2918 eligible participants aged 25-84 years from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 cycle were analyzed. Information about demographic variables, lifestyle factors, anthropometric variables, and medical comorbidities were included. Univariate and multivariate linear regression model with adjustments for potential confounders were employed to determine the association between weight range and telomere length. A non-parametrically restricted cubic spline model was used to illustrate the possible non-linear relationship.

Results

In univariate linear regression, BMI_max, BMI range, and weight range all revealed significant negative associations with telomere length. However, annual rate of BMI/weight range showed a significant positive associations with telomere length. There was no significant association between telomere length and BMI_min. After adjusting for potential confounders, the inverse associations persisted in BMI_max (β=-0.003, P<0.001), BMI range (β=-0.002, P=0.003), and weight range (β=-0.001, P=0.001). Furthermore, annual rate of BMI range (β=-0.026, P=0.009) and weight range (β=-0.010, P=0.007) presented negative associations with telomere length, after adjusting for covariates in Model 2-4. The association between BMI_min (β =-0.002, P=0.237) and telomere length still could not reach statistical significance in multivariate linear regression model. The results of restricted cubic spline analysis showed that BMI_max (P for nonlinear =0.026), BMI range (P for nonlinear =0.022), weight range (P for nonlinear =0.035), annual rate of BMI range (P for nonlinear =0.030), and annual rate of weight range (P for nonlinear =0.027) all had nonlinear inverse associations with telomere length.

Conclusions

The study suggests that weight range is inversely associated with telomere length in U.S. adults. Larger weight fluctuation may accelerate telomere shortening and aging.

The role of miRNAs in viral myocarditis, and its possible implication in induction of mRNA-based COVID-19 vaccines-induced myocarditis

BACKGROUND

Several reports of unheeded complications secondary to the current mass international rollout of SARS-COV-2 vaccines, one of which is myocarditis occurring with the FDA fully approved vaccine, Pfizer, and others.

MAIN BODY OF THE ABSTRACT

Certain miRNAs (non-coding RNA sequences) are involved in the pathogenesis in viral myocarditis, and those miRNAs are interestingly upregulated in severe COVID-19. We hypothesize that the use of mRNA-based vaccines may be triggering the release of host miRNAs or that trigger the occurrence of myocarditis. This is based on the finding of altered host miRNA expression promoting virus-induced myocarditis.

SHORT CONCLUSION

In conclusion, miRNAs are likely implicated in myocarditis associated with mRNA vaccines. Our hypothesis suggests the use of miRNA as a biomarker for the diagnosis of mRNA vaccine-induced myocarditis. Additionally, the interplay between viral miRNA and the host immune system could alter inflammatory profiles, hence suggesting the use of therapeutic inhibition to prevent such complications.

TRF2 inhibition rather than telomerase disruption drives CD4T cell dysfunction during chronic viral infection

We investigated the role of telomerase and telomere repeat-binding factor 2 (TRF2 or TERF2) in T-cell dysfunction in chronic viral infection. We found that the expression and activity of telomerase in CD4+ T (CD4T) cells from patients with hepatitis C virus (HCV) infections or people living with HIV (PLWH) were intact, but TRF2 expression was significantly inhibited at the post-transcriptional level, suggesting that TRF2 inhibition is responsible for the CD4T cell dysfunction observed during chronic viral infection. Silencing TRF2 expression in CD4T cells derived from healthy subjects induced telomeric DNA damage and CD4T cell dysfunction without affecting telomerase activity or translocation - similar to what we observed in CD4T cells from HCV patients and PLWH. These findings indicate that premature T-cell aging and dysfunction during chronic HCV or HIV infection are primarily caused by chronic immune stimulation and T-cell overactivation and/or proliferation that induce telomeric DNA damage due to TRF2 inhibition, rather than telomerase disruption. This study suggests that restoring TRF2 presents a novel approach to prevent telomeric DNA damage and premature T-cell aging, thus rejuvenating T-cell functions during chronic viral infection.

Longitudinal Study of DNA Methylation and Epigenetic Clocks Prior to and Following Test-Confirmed COVID-19 and mRNA Vaccination

The host epigenetic landscape rapidly changes during SARS-CoV-2 infection, and evidence suggest that severe COVID-19 is associated with durable scars to the epigenome. Specifically, aberrant DNA methylation changes in immune cells and alterations to epigenetic clocks in blood relate to severe COVID-19. However, a longitudinal assessment of DNA methylation states and epigenetic clocks in blood from healthy individuals prior to and following test-confirmed non-hospitalized COVID-19 has not been performed. Moreover, the impact of mRNA COVID-19 vaccines upon the host epigenome remains understudied. Here, we first examined DNA methylation states in the blood of 21 participants prior to and following test-confirmed COVID-19 diagnosis at a median time frame of 8.35 weeks; 756 CpGs were identified as differentially methylated following COVID-19 diagnosis in blood at an FDR adjusted p-value < 0.05. These CpGs were enriched in the gene body, and the northern and southern shelf regions of genes involved in metabolic pathways. Integrative analysis revealed overlap among genes identified in transcriptional SARS-CoV-2 infection datasets. Principal component-based epigenetic clock estimates of PhenoAge and GrimAge significantly increased in people over 50 following infection by an average of 2.1 and 0.84 years. In contrast, PCPhenoAge significantly decreased in people fewer than 50 following infection by an average of 2.06 years. This observed divergence in epigenetic clocks following COVID-19 was related to age and immune cell-type compositional changes in CD4+ T cells, B cells, granulocytes, plasmablasts, exhausted T cells, and naïve T cells. Complementary longitudinal epigenetic clock analyses of 36 participants prior to and following Pfizer and Moderna mRNA-based COVID-19 vaccination revealed that vaccination significantly reduced principal component-based Horvath epigenetic clock estimates in people over 50 by an average of 3.91 years for those who received Moderna. This reduction in epigenetic clock estimates was significantly related to chronological age and immune cell-type compositional changes in B cells and plasmablasts pre- and post-vaccination. These findings suggest the potential utility of epigenetic clocks as a biomarker of COVID-19 vaccine responses. Future research will need to unravel the significance and durability of short-term changes in epigenetic age related to COVID-19 exposure and mRNA vaccination.

Learned lesson from COVID-19: can routine immunizations be the first line of defense against the next pandemic?

Background

Single-cell sequencing studies on the lung microenvironment have revealed that the outcome of COVID-19 depends largely on the immune system response rather than the viral load. A robust innate immune response and a regulated adaptive immunity can prevent the worst outcomes such as hospitalization and the need for mechanical ventilation.

Main body

Intriguingly, several vaccines pertaining to the routine vaccination schedule, not only BCG, can skew the immune response towards the aforementioned beneficial effects.

Short conclusion

This means that routine immunization not only can help in the current pandemic but can also offer a rapid rescue in the subsequent epidemics or pandemics until a vaccine is developed.

SARS-CoV-2 Morbidity in the CNS and the Aged Brain Specific Vulnerability

The infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be the cause of a fatal disease known as coronavirus disease 2019 (COVID-19) affecting the lungs and other organs. Particular attention has been given to the effects of the infection on the brain due to recurring neurological symptoms associated with COVID-19, such as ischemic or hemorrhagic stroke, encephalitis and myelitis, which are far more severe in the elderly compared to younger patients. The specific vulnerability of the aged brain could derive from the impaired immune defenses, from any of the altered homeostatic mechanisms that contribute to the aging phenotype, and from particular changes in the aged brain involving neurons and glia. While neuronal modifications could contribute indirectly to the damage induced by SARS-CoV-2, glia alterations could play a more direct role, as they are involved in the immune response to viral infections. In aged patients, changes regarding glia include the accumulation of dystrophic forms, reduction of waste removal, activation of microglia and astrocytes, and immunosenescence. It is plausible to hypothesize that SARS-CoV-2 infection in the elderly may determine severe brain damage because of the frail phenotype concerning glial cells.

The proliferation of belatacept-resistant T cells requires early IFNα pathway activation

Belatacept was developed to replace calcineurin inhibitors in kidney transplantation. Its use is associated with better kidney transplant function, a lower incidence of anti-donor antibodies and higher graft survival. However, it is also associated with a higher risk of cellular rejection. We studied the activation and proliferation mechanisms of belatacept-resistant T lymphocytes (TLs), to identify new pathways for control. We performed a transcriptomic analysis on CD4⁺ CD57⁺ PD1^- memory TLs, which are responsible for a higher incidence of graft rejection, after allogeneic stimulation with activated dendritic cells (aDCs) in the presence or absence of belatacept. After six hours of contact with aDCs, the (CD4⁺ CD57⁺ PD1^- ) (CD4⁺ CD57⁺ PD1⁺ ) and (CD4⁺ CD57^- ) lymphocytes had different transcriptional profiles with or without belatacept. In the CD4⁺ CD57⁺ PD1^- population, the IFNα-dependent activation pathway was positively overrepresented, and IRF7 transcript levels were high. IRF7 was associated with IFNα/β and IL-6 regulation. The inhibition of both these cytokines in a context of belatacept treatment inhibited the proliferation of CD4⁺ CD57⁺ PD1^- T cells. Our results show that IRF7 is rapidly upregulated in belatacept-resistant CD4⁺ CD57⁺ PD1^- TLs. The inhibition of type I IFN or IL-6 in association with belatacept treatment reduces the proliferation of belatacept-resistant TLs, paving the way for new treatments for use in organ transplantation.

Telomere Shortening and Its Association with Cell Dysfunction in Lung Diseases

Telomeres are localized at the end of chromosomes to provide genome stability; however, the telomere length tends to be shortened with each cell division inducing a progressive telomere shortening (TS). In addition to age, other factors, such as exposure to pollutants, diet, stress, and disruptions in the shelterin protein complex or genes associated with telomerase induce TS. This phenomenon favors cellular senescence and genotoxic stress, which increases the risk of the development and progression of lung diseases such as idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, SARS-CoV-2 infection, and lung cancer. In an infectious environment, immune cells that exhibit TS are associated with severe lymphopenia and death, whereas in a noninfectious context, naïve T cells that exhibit TS are related to cancer progression and enhanced inflammatory processes. In this review, we discuss how TS modifies the function of the immune system cells, making them inefficient in maintaining homeostasis in the lung. Finally, we discuss the advances in drug and gene therapy for lung diseases where TS could be used as a target for future treatments.

T Cell Aging in Patients with Colorectal Cancer-What Do We Know So Far?

Simple Summary

This review describes the role of T cell aging in colorectal cancer development. T cells are important mediators in cancer immunity. Aging affects T cells, leading to various dysfunctions which can impede antitumor immunity. While some hallmarks of T cell aging have been observed in colorectal cancer patients, the functional role of such cells is not clear. Therefore, understanding how aged T cells influence overall patient outcome could potentially help in the pursue to develop new therapies for the elderly.

Abstract

Colorectal cancer (CRC) continues to be one of the most frequently diagnosed types of cancers in the world. CRC is considered to affect mostly elderly patients, and the number of diagnosed cases increases with age. Even though general screening improves outcomes, the overall survival and recurrence-free CRC rates in aged individuals are highly dependent on their history of comorbidities. Furthermore, aging is also known to alter the immune system, and especially the adaptive immune T cells. Many studies have emphasized the importance of T cell responses to CRC. Therefore, understanding how age-related changes affect the outcome in CRC patients is crucial. This review focuses on what is so far known about age-related T cell dysfunction in elderly patients with colorectal cancer and how aged T cells can mediate its development. Last, this study describes the advances in basic animal models that have potential to be used to elucidate the role of aged T cells in CRC.

Research and resource needs for understanding host immune responses to SARS-CoV-2 and COVID-19 vaccines during aging

On 16 and 17 March 2021, the National Institute of Allergy and Infectious Diseases and the National Institute of Aging convened a virtual workshop to discuss developments in SARS-CoV-2 research pertaining to immune responses in older adults, COVID-19 vaccines in both aged animals and older individuals, and to gain some perspective on the critical knowledge gaps that need addressing to establish scientific priorities for future research studies.

Humoral Immune Status in Relation to Outcomes in Patients with Idiopathic Pulmonary Fibrosis

PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a severe fibrotic lung disease, in which inflammation is thought to only play a secondary role. Several factors associated with acute exacerbations of IPF (AE-IPF) have been identified, including infections. This study investigated whether humoral immunodeficiency or increased inflammatory markers at diagnosis were associated with AE-IPF and survival.

METHODS

Four-hundred-and-nine patients diagnosed with IPF between 2011 and 2017 were retrospectively included. Immune status investigations at diagnosis included measurement of serum immunoglobulins (available in 38%), leukocyte and lymphocyte subsets in blood and bronchoalveolar lavage (BAL) fluid (available in 58%), as well as response to pneumococcal vaccination (available in 64%).

RESULTS

Serum immunoglobulins or IgG subclass levels were below the lower limit of normal in 6%. The response to pneumococcal vaccination was severely impaired in 1%. Thirteen percent of patients developed an AE-IPF (4.7% per year). AE-IPF were associated with elevated lymphocytes in BAL fluid at diagnosis (p = 0.03). Higher serum IgA and IgG at diagnosis were associated with worse survival (p = 0.01; and p = 0.04), as were an increased BAL lymphocyte percentage (p = 0.005), and higher blood leukocytes and neutrophils (p = 0.01; and p = 0.0005). In a multivariate model, only BAL lymphocyte count retained statistical significance (p = 0.007).

CONCLUSION

The prevalence of humoral immunodeficiencies was low in patients with IPF and not associated with AE-IPF or survival. Elevated lymphocytes in BAL were associated with the development of AE-IPF and worse survival. Higher serum immunoglobulins and immune cells in blood were also associated with worse survival. The local immune response in the lungs may be a target for future therapies.

The Extent of Inflammatory Cell Infiltrate and Fibrosis in Lungs of Telomere- and Surfactant-Related Familial Pulmonary Fibrosis

Familial pulmonary fibrosis (FPF) is a monogenic disease most commonly involving telomere- (TERT) or surfactant- (SFTP) related mutations. These mutations have been shown to alter lymphocytic inflammatory responses, and FPF biopsies with histological lymphocytic infiltrates have been reported. Recently, a model of a surfactant mutation in mice showed that the disease initially started with an inflammatory response followed by fibrogenesis. Since inflammation and fibrogenesis are targeted by different drugs, we investigated whether the degree of these two features co-localize or occur independently in different entities of FPF, and whether they influence survival. We quantified the number of lymphocyte aggregates per surface area, the extent of diffuse lymphocyte cell infiltrate, the number of fibroblast foci per surface area, and the percentage of fibrotic lung surface area in digitally scanned hematoxylin and eosin (H&E) sections of diagnostic surgical biopsies of patients with TERT-related FPF (TERT-PF; n = 17), SFTP-related FPF (SFTP-PF; n = 7), and sporadic idiopathic pulmonary fibrosis (sIPF; n = 10). For comparison, we included biopsies of patients with cellular non-specific interstitial pneumonia (cNSIP; n = 10), an inflammatory interstitial lung disease with high lymphocyte influx and usually responsive to immunosuppressive therapy. The degree of inflammatory cell infiltrate and fibrosis in TERT-PF and SFTP-PF was not significantly different from that in sIPF. In comparison with cNSIP, the extent of lymphocyte infiltrates was significantly lower in sIPF and TERT-PF, but not in SFTP-PF. However, in contrast with cNSIP, in sIPF, TERT-PF, and SFTP-PF, diffuse lymphocyte cell infiltrates were predominantly present and lymphocyte aggregates were only present in fibrotic areas (p < 0.0001). Furthermore, fibroblast foci and percentage of fibrotic lung surface were associated with survival (p = 0.022 and p = 0.018, respectively), while this association was not observed for lymphocyte aggregates or diffuse lymphocytic infiltration. Inflammatory cells in diagnostic lung biopsies of TERT-PF, SFTP-PF, and sIPF were largely confined to fibrotic areas. However, based on inflammation and fibrosis, no differences were found between FPF and sIPF, substantiating the histological similarities between monogenic familial and sporadic disease. Furthermore, the degree of fibrosis, rather than inflammation, correlates with survival, supporting that fibrogenesis is the key feature for therapeutic targeting of FPF.

COVID-19 infection, progression, and vaccination: Focus on obesity and related metabolic disturbances

Coronaviruses are constantly circulating in humans, causing common colds and mild respiratory infections. In contrast, infection with the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for coronavirus disease-2019 (COVID-19), can cause additional severe complications, particularly in patients with obesity and associated metabolic disturbances. Obesity is a principal causative factor in the development of the metabolic syndrome; a series of physiological, biochemical, clinical, and metabolic factors that increase the risk of obesity-associated diseases. "Metabolically unhealthy" obesity is, in addition to metabolic disturbances, also associated with immunological disturbances. As such, patients with obesity are more prone to develop serious complications from infections, including those from SARS-CoV-2. In this review, we first describe how obesity and related metabolic disturbances increase the risk of SARS-CoV-2 infection. Then, mechanisms contributing to COVID-19 complications and poor prognosis in these patients are discussed. Finally, we discuss how obesity potentially reduces long-term COVID-19 vaccination efficacy. Despite encouraging COVID-19 vaccination results in patients with obesity and related metabolic disturbances in the short-term, it is becoming increasingly evident that long-term COVID-19 vaccination efficacy should be closely monitored in this vulnerable group.

Antibody Responsiveness to Influenza: What Drives It?

The induction of a specific antibody response has long been accepted as a serological hallmark of recent infection or antigen exposure. Much of our understanding of the influenza antibody response has been derived from studying antibodies that target the hemagglutinin (HA) protein. However, growing evidence points to limitations associated with this approach. In this review, we aim to highlight the issue of antibody non-responsiveness after influenza virus infection and vaccination. We will then provide an overview of the major factors known to influence antibody responsiveness to influenza after infection and vaccination. We discuss the biological factors such as age, sex, influence of prior immunity, genetics, and some chronic infections that may affect the induction of influenza antibody responses. We also discuss the technical factors, such as assay choices, strain variations, and viral properties that may influence the sensitivity of the assays used to measure influenza antibodies. Understanding these factors will hopefully provide a more comprehensive picture of what influenza immunogenicity and protection means, which will be important in our effort to improve influenza vaccines.

The Effects of Physical Activity on the Aging of Circulating Immune Cells in Humans: A Systematic Review

Age-induced cellular senescence leads to a decline in efficacy of immune response and an increase in morbidity and mortality. Physical activity may be an intervention to slow down or reverse this process for elderly individuals or even delay it via enhanced activity over their lifespan. The aim of this systematic review was to analyze and discuss the current evidence of the effects of physical activity on senescence in leukocyte subpopulations. Two electronic databases (PubMed, Web of Science) were scanned in July 2020. Studies performing endurance or resistance exercise programs and investigating leukocytes of healthy, particularly elderly subjects were included. Nine human studies were identified, including a total of 440 participants, of which two studies examined different types of exercise training retrospectively, three conducted resistance exercise, three endurance exercise, and one endurance vs. resistance training. Results revealed that exercise training increased the naïve subsets of peripheral T-helper cells and cytotoxic T-cells, whereas the senescent and effector memory T-cells re-expresses CD45RA (TEMRA) subsets decreased. Moreover, the percentage of T-helper- compared to cytotoxic T-cells increased. The results suggest that physical activity reduces or slows down cellular immunosenescence. Endurance exercise seems to affect cellular senescence in a more positive way than resistance training. However, training contents and sex also influence senescent cells. Explicit mechanisms need to be clarified.

Emerging Molecular Connections between NM23 Proteins, Telomeres and Telomere-Associated Factors: Implications in Cancer Metastasis and Ageing

The metastasis suppressor function of NM23 proteins is widely understood. Multiple enzymatic activities of NM23 proteins have also been identified. However, relatively less known interesting aspects are being revealed from recent developments that corroborate the telomeric interactions of NM23 proteins. Telomeres are known to regulate essential physiological events such as metastasis, ageing, and cellular differentiation via inter-connected signalling pathways. Here, we review the literature on the association of NM23 proteins with telomeres or telomere-related factors, and discuss the potential implications of emerging telomeric functions of NM23 proteins. Further understanding of these aspects might be instrumental in better understanding the metastasis suppressor functions of NM23 proteins.

Hallmarks and detection techniques of cellular senescence and cellular ageing in immune cells

The ageing of the global population brings about unprecedented challenges. Chronic age-related diseases in an increasing number of people represent an enormous burden for health and social care. The immune system deteriorates during ageing and contributes to many of these age-associated diseases due to its pivotal role in pathogen clearance, tissue homeostasis and maintenance. Moreover, in order to develop treatments for COVID-19, we urgently need to acquire more knowledge about the aged immune system, as older adults are disproportionally and more severely affected. Changes with age lead to impaired responses to infections, malignancies and vaccination, and are accompanied by chronic, low-degree inflammation, which together is termed immunosenescence. However, the molecular and cellular mechanisms that underlie immunosenescence, termed immune cell senescence, are mostly unknown. Cellular senescence, characterised by an irreversible cell cycle arrest, is thought to be the cause of tissue and organismal ageing. Thus, better understanding of cellular senescence in immune populations at single-cell level may provide us with insight into how immune cell senescence develops over the life time of an individual. In this review, we will briefly introduce the phenotypic characterisation of aged innate and adaptive immune cells, which also contributes to overall immunosenescence, including subsets and function. Next, we will focus on the different hallmarks of cellular senescence and cellular ageing, and the detection techniques most suitable for immune cells. Applying these techniques will deepen our understanding of immune cell senescence and to discover potential druggable pathways, which can be modulated to reverse immune ageing.

Aging induces B cell defects and decreased antibody responses to influenza infection and vaccination

Background

Aging is characterized by a progressive decline in the capacity of the immune system to fight influenza virus infection and to respond to vaccination. Among the several factors involved, in addition to increased frailty and high-risk conditions, the age-associated decrease in cellular and humoral immune responses plays a relevant role. This is in large part due to inflammaging, the chronic low-grade inflammatory status of the elderly, associated with intrinsic inflammation of the immune cells and decreased immune function.

Results

Aging is usually associated with reduced influenza virus-specific and influenza vaccine-specific antibody responses but some elderly individuals with higher pre-exposure antibody titers, due to a previous infection or vaccination, have less probability to get infected. Examples of this exception are the elderly individuals infected during the 2009 pandemic season who made antibodies with broader epitope recognition and higher avidity than those made by younger individuals. Several studies have allowed the identification of B cell intrinsic defects accounting for sub-optimal antibody responses of elderly individuals. These defects include 1) reduced class switch recombination, responsible for the generation of a secondary response of class switched antibodies, 2) reduced de novo somatic hypermutation of the antibody variable region, 3) reduced binding and neutralization capacity, as well as binding specificity, of the secreted antibodies, 4) increased epigenetic modifications that are associated with lower antibody responses, 5) increased frequencies of inflammatory B cell subsets, and 6) shorter telomeres.

Conclusions

Although influenza vaccination represents the most effective way to prevent influenza infection, vaccines with greater immunogenicity are needed to improve the response of elderly individuals. Recent advances in technology have made possible a broad approach to better understand the age-associated changes in immune cells, needed to design tailored vaccines and effective therapeutic strategies that will be able to improve the immune response of vulnerable individuals.

Pathogen burden and leukocyte telomere length in the United States

BACKGROUND

Prior studies in humans have suggested that telomere shortening may be accelerated by infection, but research on multiple pathogens and use of large population-based study samples has been limited. We estimated cross-sectional associations between seropositivity to five persistent pathogens (Herpes Simplex Virus Type-1 (HSV-1), Herpes Simplex Virus Type-2 (HSV-2), cytomegalovirus (CMV), Helicobacter pylori (H.pylori), and Hepatitis B) as well as total pathogen burden and leukocyte telomere length. Data were derived from the National Health and Nutrition Examination Survey (1999-2000) for individuals 20-49 years of age, N = 1708. We analyzed the influence of each pathogen separately, a pathogen count score and a latent class model of pathogen burden on log telomere length using linear regression models, adjusted for covariates.

RESULTS

Individuals in a latent pathogen burden class characterized by high probabilities of infection with HSV-1, CMV, and H. pylori, had significantly decreased log telomere length (- 0.30 [95% CI: - 0.36, - 0.24]) compared to those in a latent class characterized by low probabilities of all five infections. There were limited significant associations using other pathogen measures.

CONCLUSIONS

These results suggest that infection with specific combinations of pathogens may be one mechanism contributing to accelerated cellular senescence with possible origins early in the life course.

Immunotherapy in older patients with cancer

Ageing implicates a remodeling of our immune system, which is a consequence of the physiological senescence of our cells and tissues coupled with environmental factors and chronic antigen exposure. An immune system that senesces includes more differentiated cells with accumulation of highly differentiated CD4 and CD8 T cells. The pool of naive T cells decreases with the exponential thymic involution induced by age. Differentiated T cells have similar, if not higher, functional capacities but scarce studies are looking at the impact of senescence among specific T cells. After a stimulation, other immune cells (monocytes, dendritic cells and NK) are functionally altered during ageing. It is as if the immune system was more efficient at the basal level, but less efficient after a stimulation in the old compared to young people, likely due to less reserve. Concerning the clinical impact, older people are more prone to certain pathogens and their clinical manifestations differ from the younger people. Severe flu and VZV reactivation are more frequent with an altered cellular response to vaccination. Vaccination failure can have detrimental consequences in people presenting frailty criteria. Old people frailty is majored by their comorbidities and diseases like cancer. Thus, chemotherapies are employed with circumspection in older patients. The use of anti-PD-1/PD-L1 immunotherapies is therefore attractive, because of less side effects with a better response compared to chemotherapy. Old persons inclusion is lacking in current studies and clinical trials. Some subgroups or pooled analyses confirm the gain in response without increased toxicities in older patients but their inclusion criteria differ from the real-life practice. Specific studies focusing on this population are needed because of the increasing cancer incidence with age and the overall ageing of the population.

Results from the German Chronic Kidney Disease (GCKD) study support association of relative telomere length with mortality in a large cohort of patients with moderate chronic kidney disease

Telomere length is known to be inversely associated with aging and has been proposed as a marker for aging-related diseases. Telomere attrition can be accelerated by oxidative stress and inflammation, both commonly present in patients with chronic kidney disease. Here, we investigated whether relative telomere length is associated with mortality in a large cohort of patients with chronic kidney disease stage G3 and A1-3 or G1-2 with overt proteinuria (A3) at enrollment. Relative telomere length was quantified in peripheral blood by a quantitative PCR method in 4,955 patients from the GCKD study, an ongoing prospective observational cohort. Complete four-year follow-up was available from 4,926 patients in whom we recorded 354 deaths. Relative telomere length was a strong and independent predictor of all-cause mortality. Each decrease of 0.1 relative telomere length unit was highly associated with a 14% increased risk of death (hazard ratio1.14 [95% confidence interval 1.06-1.22]) in a model adjusted for age, sex, baseline eGFR, urine albumin/creatinine ratio, diabetes mellitus, prevalent cardiovascular disease, LDL-cholesterol, HDL-cholesterol, smoking, body mass index, systolic and diastolic blood pressure, C-reactive protein and serum albumin. This translated to a 75% higher risk for those in the lowest compared to the highest quartile of relative telomere length. The association was mainly driven by 117 cardiovascular deaths (1.20 [1.05-1.35]) as well as 67 deaths due to infections (1.27 [1.07-1.50]). Thus, our findings support an association of shorter telomere length with all-cause mortality, cardiovascular mortality and death due to infections in patients with moderate chronic kidney disease.

Measuring biological aging in humans: A quest

The global population of individuals over the age of 65 is growing at an unprecedented rate and is expected to reach 1.6 billion by 2050. Most older individuals are affected by multiple chronic diseases, leading to complex drug treatments and increased risk of physical and cognitive disability. Improving or preserving the health and quality of life of these individuals is challenging due to a lack of well-established clinical guidelines. Physicians are often forced to engage in cycles of "trial and error" that are centered on palliative treatment of symptoms rather than the root cause, often resulting in dubious outcomes. Recently, geroscience challenged this view, proposing that the underlying biological mechanisms of aging are central to the global increase in susceptibility to disease and disability that occurs with aging. In fact, strong correlations have recently been revealed between health dimensions and phenotypes that are typical of aging, especially with autophagy, mitochondrial function, cellular senescence, and DNA methylation. Current research focuses on measuring the pace of aging to identify individuals who are "aging faster" to test and develop interventions that could prevent or delay the progression of multimorbidity and disability with aging. Understanding how the underlying biological mechanisms of aging connect to and impact longitudinal changes in health trajectories offers a unique opportunity to identify resilience mechanisms, their dynamic changes, and their impact on stress responses. Harnessing how to evoke and control resilience mechanisms in individuals with successful aging could lead to writing a new chapter in human medicine.

Cellular aging over 13 years associated with incident antinuclear antibody positivity in the Baltimore Longitudinal Study of Aging

Age-associated increases in antinuclear antibodies (ANA) in the general population are commonly noted but the mechanisms underlying this observation are unclear. This study aims to evaluate whether shorter peripheral blood mononuclear cell (PBMC) telomere length, a marker of more advanced biological age, is associated with ANA positivity prevalence and incidence in middle and older aged autoimmune disease-free individuals from the Baltimore Longitudinal Study of Aging (BLSA). Telomere length was measured by Southern Blot and categorized into tertiles. ANA was measured in a 1:80 and a 1:160 dilution of sera by immunofluorescence using HEp-2 cells (seropositive = 3 or 4). Multiple logistic regression was used to estimate the odds ratios and 95% confidence intervals of ANA positivity comparing the shorter tertiles of telomere length to the longest tertile for two cross-sectional points in time and then longitudinally to assess the association between shorter telomere length and incident ANA positivity. Cross-sectional analyses were adjusted for sex, race and BMI (N = 368 baseline, N = 370 follow-up) and longitudinal analyses were adjusted for sex, race, BMI and time between baseline and follow-up (N = 246). No statistically significant cross-sectional associations were observed at baseline or follow-up. Among those where ANA negative at baseline, individuals with shorter telomeres were more likely to be ANA positive at follow-up, an average 13 years later. Individuals with short telomeres at both time periods were more likely to be ANA positive. Findings suggest that ANA positivity in the general population may be indicative of immune dysfunction resulting from advanced cellular aging processes.

Host Factors Impact Vaccine Efficacy: Implications for Seasonal and Universal Influenza Vaccine Programs

Influenza is a global public health problem. Current seasonal influenza vaccines have highly variable efficacy, and thus attempts to develop broadly protective universal influenza vaccines with durable protection are under way. While much attention is given to the virus-related factors contributing to inconsistent vaccine responses, host-associated factors are often neglected. Growing evidences suggest that host factors including age, biological sex, pregnancy, and immune history play important roles as modifiers of influenza virus vaccine efficacy. We hypothesize that host genetics, the hormonal milieu, and gut microbiota contribute to host-related differences in influenza virus vaccine efficacy. This review highlights the current insights and future perspectives into host-specific factors that impact influenza vaccine-induced immunity and protection. Consideration of the host factors that affect influenza vaccine-induced immunity might improve influenza vaccines by providing empirical evidence for optimizing or even personalizing vaccine type, dose, and use of adjuvants for current seasonal and future universal influenza vaccines.

Host Factors Impact Vaccine Efficacy: Implications for Seasonal and Universal Influenza Vaccine Programs

Influenza is a global public health problem. Current seasonal influenza vaccines have highly variable efficacy, and thus attempts to develop broadly protective universal influenza vaccines with durable protection are under way. While much attention is given to the virus-related factors contributing to inconsistent vaccine responses, host-associated factors are often neglected. Growing evidences suggest that host factors including age, biological sex, pregnancy, and immune history play important roles as modifiers of influenza virus vaccine efficacy. We hypothesize that host genetics, the hormonal milieu, and gut microbiota contribute to host-related differences in influenza virus vaccine efficacy. This review highlights the current insights and future perspectives into host-specific factors that impact influenza vaccine-induced immunity and protection. Consideration of the host factors that affect influenza vaccine-induced immunity might improve influenza vaccines by providing empirical evidence for optimizing or even personalizing vaccine type, dose, and use of adjuvants for current seasonal and future universal influenza vaccines.

Telomere length and cognitive function: Differential patterns across sociodemographic groups

OBJECTIVE

The present study investigates whether associations between telomere length (TL) and cognitive performance across multiple domains are moderated by poverty status and race.

METHOD

Participants were 325 African American and White urban-dwelling adults (M age = 47.9 years; 49.5% African American; 50.2% female; 48.9% living in poverty) from the Healthy Aging in Neighborhoods of Diversity across the Life Span study. TL was assayed from peripheral blood mononuclear cells using quantitative polymerase chain reactions. Multivariable regression analyses examined interactions of TL, poverty status, and race with performance on the following cognitive tests: Trail-Making Test Parts A and B, Digit Span Forward and Backward, semantic verbal fluency, Brief Test of Attention, Benton Visual Retention Test (BVRT), and California Verbal Learning Test-II total learning, short-delay free recall, and long-delay free recall scores. Analyses adjusted for age, sex, and high school-or-greater educational attainment.

RESULTS

Significant three-way interactions of TL × Poverty Status × Race revealed that, among White participants living in poverty, shorter TL was associated with worse performance on Digit Span Forward and Backward (ps<.05). Additionally, significant two-way interactions of TL × Poverty Status revealed that, among all participants living in poverty, shorter TL was associated with worse performance on the Trail-Making Test Part B and the BVRT (ps<.05).

CONCLUSIONS

TL may be differentially associated with aspects of attention, executive functioning, and memory among individuals living in poverty, who may be uniquely vulnerable to adverse effects of shorter telomeres. Replication of these findings is needed to determine their generalizability. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

The protective function of non-coding DNA in DNA damage accumulation with age and its roles in age-related diseases

Aging is a progressive decline of physiological function in tissue and organ accompanying both accumulation of DNA damage and reduction of non-coding DNA. Peripheral non-coding DNA/heterochromatin has been proposed to protect the genome and centrally-located protein-coding sequences in soma and male germ cells against radiation and the invasion of exogenous nucleic acids. Therefore, this review summarizes the reduction of non-coding DNA/heterochromatin (including telomeric DNA and rDNA) and DNA damage accumulation during normal physiological aging and in various aging-related diseases. Based on analysis of data, it is found that DNA damage accumulation is roughly negatively correlated with the reduction of non-coding DNA and therefore speculated that DNA damage accumulation is likely due to the reduction of non-coding DNA protection in genome defense during aging. Therefore, it is proposed here that means to increase the total amount of non-coding DNA and/or heterochromatin prior to the onset of these diseases could potentially better protect the genome and protein-coding DNA, reduce the incidence of aging-related diseases, and thus lead to better health during aging.

Human T Cell Differentiation Negatively Regulates Telomerase Expression Resulting in Reduced Activation-Induced Proliferation and Survival

Maintenance of telomeres is essential for preserving T cell proliferative responses yet the precise role of telomerase in human T cell differentiation, function, and aging is not fully understood. Here we analyzed human telomerase reverse transcriptase (hTERT) expression and telomerase activity in six T cell subsets from 111 human adults and found that levels of hTERT mRNA and telomerase activity had an ordered decrease from naïve (TN) to central memory (TCM) to effector memory (TEM) cells and were higher in CD4+ than their corresponding CD8+ subsets. This differentiation-related reduction of hTERT mRNA and telomerase activity was preserved after activation. Furthermore, the levels of hTERT mRNA and telomerase activity were positively correlated with the degree of activation-induced proliferation and survival of T cells in vitro. Partial knockdown of hTERT by an anti-sense oligo in naïve CD4+ cells led to a modest but significant reduction of cell proliferation. Finally, we found that activation-induced levels of telomerase activity in CD4+ TN and TCM cells were significantly lower in old than in young subjects. These findings reveal that hTERT/telomerase expression progressively declines during T cell differentiation and age-associated reduction of activation-induced expression of hTERT/telomerase mainly affects naïve CD4+ T cells and suggest that enhancing telomerase activity could be a strategy to improve T cell function in the elderly.

Effect of homeostatic T-cell proliferation in the vaccine responsiveness against influenza in elderly people

Background

Seasonal influenza virus infection is a significant cause of morbimortality in the elderly. However, there is poor vaccine efficacy in this population due to immunosenescence. We aimed to explore several homeostatic parameters in the elderly that could impact influenza vaccine responsiveness.

Methods

Subjects (> 60 years old) who were vaccinated against influenza virus were included, and the vaccine response was measured by a haemagglutination inhibition (HAI) test. At baseline, peripheral CD4 and CD8 T-cells were phenotypically characterized. Thymic function and the levels of different inflammation-related biomarkers, including Lipopolysaccharide Binding Protein (LBP) and anti-cytomegalovirus (CMV) IgG antibodies, were also measured.

Results

Influenza vaccine non-responders showed a tendency of higher frequency of regulatory T-cells (Tregs) before vaccination than responders (1.49 [1.08–1.85] vs. 1.12 [0.94–1.63], respectively, p = 0.061), as well as higher expression of the proliferation marker Ki67 in Tregs and different CD4 and CD8 T-cell maturational subsets. The levels of inflammation-related biomarkers correlated with the frequencies of different proliferating T-cell subsets and with thymic function (e.g., thymic function with D-dimers, r = − 0.442, p = 0.001).

Conclusions

Age-related homeostatic dysregulation involving the proliferation of CD4 and CD8 T-cell subsets, including Tregs, was related to a limited responsiveness to influenza vaccination and a higher inflammatory status in a cohort of elderly people.

Electronic supplementary material

The online version of this article (10.1186/s12979-019-0154-y) contains supplementary material, which is available to authorized users.

The paternal age at conception effect on offspring telomere length: mechanistic, comparative and adaptive perspectives

Telomeres are repeating DNA found at the ends of chromosomes that, in the absence of restorative processes, shorten with cell replications and are implicated as a cause of senescence. It appears that sperm telomere length (TL) increases with age in humans, and as a result offspring of older fathers inherit longer telomeres. We review possible mechanisms underlying this paternal age at conception (PAC) effect on TL, including sperm telomere extension due to telomerase activity, age-dependent changes in the spermatogonial stem cell population (possibly driven by 'selfish' spermatogonia) and non-causal confounding. In contrast to the lengthening of TL with PAC, higher maternal age at conception appears to predict shorter offspring TL in humans. We review evidence for heterogeneity across species in the PAC effect on TL, which could relate to differences in statistical power, sperm production rates or testicular telomerase activity. Finally, we review the hypothesis that the PAC effect on TL may allow a gradual multi-generational adaptive calibration of maintenance effort, and reproductive lifespan, to local demographic conditions: descendants of males who reproduced at a later age are likely to find themselves in an environment where increased maintenance effort, allowing later reproduction, represents a fitness improving resource allocation.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.

Mononuclear Cell Telomere Attrition Is Associated with Overall Survival after Nonmyeloablative Allogeneic Hematopoietic Cell Transplantation for Hematologic Malignancies

After allogeneic hematopoietic cell transplantation (allo-HCT), transplanted cells rapidly undergo multiple rounds of division. This may cause extensive telomere attrition, which could potentially prohibit further cell division and lead to increased mortality. We therefore characterized the development in telomere length after nonmyeloablative allo-HCT in 240 consecutive patients transplanted because of hematologic malignancies and tested the hypothesis that extensive telomere attrition post-transplant is associated with low overall survival. Telomere length was measured using quantitative PCR in mononuclear cells obtained from donors and recipients pretransplant and in follow-up samples from recipients post-transplant. Telomere attrition at 9 to 15 months post-transplant was calculated as the difference between recipient telomere length at 9 to 15 months post-transplant and donor pretransplant telomere length, divided by donor pretransplant telomere length. Although allo-HCT led to shorter mean telomere length in recipients when compared with donors, recipients had longer mean telomere length 9 to 15 months post-transplant than they had pretransplant. When compared with donor telomeres, recipients with extensive telomere attrition at 9 to 15 months post-transplant had low overall survival (10-year survival from 9 to 15 months post-transplant and onward: 68% in the tertile with least telomere attrition, 57% in the middle tertile, and 39% in the tertile with most attrition; log-rank P = .01). Similarly, after adjusting for potential confounders, recipients with extensive telomere attrition had high all-cause mortality (multivariable adjusted hazard ratio, 1.84 per standard deviation of telomere attrition at 9 to 15 months post-transplant; 95% confidence interval, 1.25 to 2.72; P = .002) and high relapse-related mortality (subhazard ratio, 2.07; 95% confidence interval, 1.14 to 3.76; P = .02). Taken together, telomere attrition may be a clinically relevant marker for identifying patients at high risk of mortality.

Weight Loss Maintenance and Cellular Aging in the Supporting Health Through Nutrition and Exercise Study

OBJECTIVE

The aim of the study was to determine, within a weight loss clinical trial for obesity, the impact of intervention arm, weight change, and weight loss maintenance on telomere length (TL).

METHODS

Adults (N = 194) with a body mass index between 30 and 45 were randomized to a 5.5-month weight loss program with (n = 100) or without (n = 94) mindfulness training and identical diet-exercise guidelines. We assessed TL at baseline and 3-, 6-, and 12-month postbaseline in immune cell populations (primarily in peripheral blood mononuclear cells [PBMCs], but also in granulocytes and T and B lymphocytes). We defined weight loss maintenance as having lost at least 5% or 10% of body weight (tested in separate models) from preintervention to postintervention, and having maintained this loss at 12 months. We predicted that greater weight loss and weight loss maintenance would be associated with TL lengthening.

RESULTS

Neither weight loss intervention significantly predicted TL change nor did amount of weight change, at any time point. Across all participants, weight loss maintenance of at least 10% was associated with longer PBMC TL (b = 239.08, 95% CI = 0.92 to 477.25, p = .049), CD8+ TL (b = 417.26, 95% CI = 58.95 to 775.57, p = .023), and longer granulocyte TL (b = 191.56, 95% CI = -4.23 to 387.35, p = .055) at 12 months after accounting for baseline TL. Weight loss maintenance of 5% or more was associated with longer PBMC TL (b = 163.32, 95% CI = 4.00 to 320.62, p = .045) at 12 months after accounting for baseline TL. These tests should be interpreted in light of corrections for multiple tests.

CONCLUSIONS

Among individuals with obesity, losing and maintaining a weight loss of 10% or more may lead to TL lengthening, which may portend improved immune and metabolic function. TL lengthening in this study is of unknown duration beyond 12 months and requires further study.

TRIAL REGISTRATION

Clinicaltrials.govidentifierNCT00960414; Open Science Framework (OSF) preregistration: https://osf.io/t3r2g/.

Improved CD4 T cell profile in HIV-infected subjects on maraviroc-containing therapy is associated with better responsiveness to HBV vaccination

Background

Maraviroc-containing combined antiretroviral therapy (MVC-cART) improved the response to the hepatitis B virus (HBV) vaccine in HIV-infected subjects younger than 50 years old. We aimed here to explore the effect of this antiretroviral therapy on different immunological parameters that could account for this effect.

Methods

We analysed baseline samples of vaccinated subjects under 50 years old (n = 41). We characterized the maturational subsets and the expression of activation, senescence and prone-to-apoptosis markers on CD4 T-cells; we also quantified T-regulatory cells (Treg) and dendritic cell (DC) subsets. We used binary logistic regression to evaluate the immunological impact of MVC-cART, correlation with MVC exposure and linear regression for association with the magnitude of the HBV vaccine response.

Results

HIV-infected subjects on MVC-cART prior to vaccination showed increased recent thymic emigrants levels and reduced myeloid-DC levels. A longer exposure to MVC-cART was associated with lower frequencies of Tregs and activated and proliferating CD4 T-cells. Furthermore, the frequencies of activated and proliferating CD4 T-cells were inversely associated with the magnitude of the HBV vaccine response.

Conclusion

The beneficial effect of MVC-cART in the HBV vaccine response in subjects below 50 years old could be partially mediated by its reducing effect on the frequencies of activated and proliferating CD4 T-cells prior to vaccination.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1617-1) contains supplementary material, which is available to authorized users.

Elderly human hematopoietic progenitor cells express cellular senescence markers and are more susceptible to pyroptosis

The maintenance of effective immunity over time is dependent on the capacity of hematopoietic stem cells (HSCs) to sustain the pool of immunocompetent mature cells. Decline of immune competence with old age may stem from HSC defects, including reduced self-renewal potential and impaired lymphopoiesis, as suggested in murine models. To obtain further insights into aging-related alteration of hematopoiesis, we performed a comprehensive study of blood hematopoietic progenitor cells (HPCs) from older humans. In the elderly, HPCs present active oxidative phosphorylation and are pressed to enter cell cycling. However, p53-p21 and p15 cell senescence pathways, associated with telomerase activity deficiency, strong telomere attrition, and oxidative stress, are engaged, thus limiting cell cycling. Moreover, survival of old HPCs is impacted by pyroptosis, an inflammatory form of programmed cell death. Lastly, telomerase activity deficiency and telomere length attrition of old HPCs may be passed on to progeny cells such as naive T lymphocytes, further highlighting the poor hematopoietic potential of the elderly. This pre-senescent profile is characteristic of the multiple intrinsic and extrinsic factors affecting HPCs in elderly individuals and represents a major obstacle in terms of immune reconstitution and efficacy with advanced age.

Donor telomere length and causes of death after unrelated hematopoietic cell transplantation in patients with marrow failure

Previous studies have suggested that longer donor leukocyte telomere length (TL) is associated with improved survival after hematopoietic cell transplantation (HCT) in severe aplastic anemia (SAA). This study aimed to determine whether cell-specific lymphocyte TL is associated with certain post-HCT causes of death. We used flow cytometry and fluorescence in situ hybridization to measure TL in donor total lymphocytes and subsets: naïve enriched T cells (CD45RA⁺CD20^-), memory enriched T cells (CD45RA^-CD20^-), natural killer (NK) fully differentiated T cells (CD45RA⁺CD57⁺), and B cells (CD45RA⁺CD20⁺). Competing risk survival regression was used for cause-specific death analyses. Clinical data and biospecimens were available from the Center for International Blood and Marrow Transplant Research database and biorepository. The study included 197 patients who underwent unrelated-donor HCT for SAA between 1988 and 2004. The median age at HCT was 15 years (range, 0.5-40 years), and the median follow-up was 5 years (range, <1 month to 20.7 years). Longer donor TL in all cell subsets was associated with lower risk of all-cause mortality (P < .01). In cause-specific mortality analyses, longer TL in B cells (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.46-0.87; P = .006) and possibly NK fully differentiated T cells (HR, 0.7; 95% CI, 0.51 to 0.97; P = .03) was associated with lower risk of infection-related death. Donor TL in other tested lymphocyte subsets was not statistically significantly associated with death resulting from graft-versus-host disease or graft failure (P > .05). However, a trend toward excess risk of graft-versus-host mortality was noted (HR for total lymphocyte TL, 1.26; P = .15). In conclusion, longer donor TL was associated with reduced rate of infection-related deaths after HCT for SAA.

The fetal programming of telomere biology hypothesis: an update

Research on mechanisms underlying fetal programming of health and disease risk has focused primarily on processes that are specific to cell types, organs or phenotypes of interest. However, the observation that developmental conditions concomitantly influence a diverse set of phenotypes, the majority of which are implicated in age-related disorders, raises the possibility that such developmental conditions may additionally exert effects via a common underlying mechanism that involves cellular/molecular ageing-related processes. In this context, we submit that telomere biology represents a process of particular interest in humans because, firstly, this system represents among the most salient antecedent cellular phenotypes for common age-related disorders; secondly, its initial (newborn) setting appears to be particularly important for its long-term effects; and thirdly, its initial setting appears to be plastic and under developmental regulation. We propose that the effects of suboptimal intrauterine conditions on the initial setting of telomere length and telomerase expression/activity capacity may be mediated by the programming actions of stress-related maternal-placental-fetal oxidative, immune, endocrine and metabolic pathways in a manner that may ultimately accelerate cellular dysfunction, ageing and disease susceptibility over the lifespan. This perspectives paper provides an overview of each of the elements underlying this hypothesis, with an emphasis on recent developments, findings and future directions.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.

Long term effects of radiation exposure on telomere lengths of leukocytes and its associated biomarkers among atomic-bomb survivors

Ionizing radiation (IR) is a major source of cellular damage and the immediate cellular response to IR has been well characterized. But the long-term impact of IR on cell function and its relationship with aging are not known. Here, we examined the IR effects on telomere length and other biomarkers 50 to 68 years post-exposure (two time points per person) in survivors of the atomic bombing at Hiroshima during WWII. We found that telomere length of leukocytes was inversely correlated with the dose of IR (p=0.008), and this effect was primarily found in survivors who were exposed at younger ages; specifically those <12 years old (p=0.0004). Although a dose-related retardation of telomere shortening with age was observed in the cross-sectional data, longitudinal follow-up after 11 years did not show IR exposure-related alteration of the rate of telomere shortening with age. In addition, IR diminished the associations between telomere length and selected aging biomarkers that were observed in survivors with no dose. These included uric acid metabolism, cytokines, and blood T cell counts. These findings showed long-lasting detrimental effects of IR on telomere length of leukocytes in both dose- and age-at-exposure dependent manner, and on alterations of biomarkers with aging.

Association between a Suppressive Combined Antiretroviral Therapy Containing Maraviroc and the Hepatitis B Virus Vaccine Response

The response to the HBV vaccine in HIV-infected patients is deficient. Our aim was to analyze whether a suppressive combined antiretroviral treatment (cART) containing maraviroc (MVC-cART) was associated with a better response to HBV vaccine. Fifty-seven patients on suppressor cART were administered the HBV vaccine. The final response, the early response, and the maintenance of the response were assessed. An anti-HBs titer of >10 mIU/ml was considered a positive response. A subgroup of subjects was simultaneously vaccinated against hepatitis A virus (HAV). Lineal regression analyses were performed to determine demographic, clinical, and immunological factors associated with the anti-HBs titer. Vaccine response was achieved in 90% of the subjects. After 1 year, 81% maintained protective titers. Only simultaneous HAV vaccination was independently associated with the magnitude of the response in anti-HBs titers, with a P value of 0.045 and a regression coefficient (B) [95% confident interval (CI)] of 236 [5 to 468]. In subjects ≤50 years old (n = 42), MVC-cART was independently associated with the magnitude of the response (P = 0.009; B [95% CI], 297 [79 to 516]) together with previous vaccination and simultaneous HAV vaccination. High rates of HBV vaccine response can be achieved by revaccination, simultaneous HAV vaccination, and administration of cARTs including MVC. MVC may be considered for future vaccination protocols in patients on suppressive cART.

In aged primary T cells, mitochondrial stress contributes to telomere attrition measured by a novel imaging flow cytometry assay

The decline of the immune system with age known as immune senescence contributes to inefficient pathogen clearance and is a key risk factor for many aged‐related diseases. However, reversing or halting immune aging requires more knowledge about the cell biology of senescence in immune cells. Telomere shortening, low autophagy and mitochondrial dysfunction have been shown to underpin cell senescence. While autophagy has been found to control mitochondrial damage, no link has been made to telomere attrition. In contrast, mitochondrial stress can contribute to telomere attrition and vice versa. Whereas this link has been investigated in fibroblasts or cell lines, it is unclear whether this link exists in primary cells such as human lymphocytes and whether autophagy contributes to it. As traditional methods for measuring telomere length are low throughput or unsuitable for the analysis of cell subtypes within a mixed population of primary cells, we have developed a novel sensitive flow‐FISH assay using the imaging flow cytometer. Using this assay, we show a correlation between age and increased mitochondrial reactive oxygen species in CD8⁺ T‐cell subsets, but not with autophagy. Telomere shortening within the CD8⁺ subset could be prevented in vitro by treatment with a ROS scavenger. Our novel assay is a sensitive assay to measure relative telomere length in primary cells and has revealed ROS as a contributing factor to the decline in telomere length.

Aging, cytomegalovirus (CMV) and influenza vaccine responses

Influenza vaccination is less effective in elderly as compared to young individuals. Several studies have identified immune biomarkers able to predict a protective humoral immune response to the vaccine. In this review, we summarize current knowledge on the effects of aging on influenza vaccine responses and on biomarkers so far identified, and we discuss the relevance of latent cytomegalovirus (CMV) infection on these vaccine responses.

Persistent Herpesvirus Infections and Telomere Attrition Over 3 Years in the Whitehall II Cohort

The determinants of telomere attrition, a potential marker of cellular aging, are not well understood. Persistent herpesvirus infections including cytomegalovirus (CMV) infection may be particularly important for telomere dynamics via mechanisms such as inflammation, oxidative stress, and their impact on peripheral blood lymphocyte composition. This study examined the association of 4 human herpesviruses (CMV, herpes simplex virus type 1, human herpesvirus type 6, and Epstein-Barr virus) with change in leukocyte telomere length (LTL) over 3 years in 400 healthy individuals (aged 53-76 years) from the Whitehall II cohort. CMV, herpes simplex virus type 1, and human herpesvirus 6 infection were independently associated with greater 3-year LTL attrition, with no association found for Epstein-Barr virus. The magnitudes of these associations were large, for example, the equivalent of almost 12 years of chronological age for those CMV seropositive. Seropositivity to more herpesviruses was additively associated with greater LTL attrition (3 herpesviruses vs none, β = -0.07 and P = .02; 4 infections vs none, β = -0.14 and P < .001). Higher immunoglobulin G antibody levels among those seropositive to CMV were also associated with shorter LTL at follow-up. These associations were robust to adjustment for age, sex, employment grade, body mass index, and smoking status. These results suggest that exposure to infectious agents should be an important consideration in future studies of telomere dynamics.

Successful and Maladaptive T Cell Aging

Throughout life, the T cell system adapts to shifting resources and demands, resulting in a fundamentally restructured immune system in older individuals. Here we review the cellular and molecular features of an aged immune system and discuss the trade-offs inherent to these adaptive mechanisms. Processes include homeostatic proliferation that maintains compartment size at the expense of partial loss in stemness and incomplete differentiation and the activation of negative regulatory programs, which constrain effector T cell expansion and prevent increasing oligoclonality but also interfere with memory cell generation. We propose that immune failure occurs when adaptive strategies developed by the aging T cell system fail and also discuss how, in some settings, the programs associated with T cell aging culminates in a maladaptive response that directly contributes to chronic inflammatory disease.