Telomeres and immune competency

Current and Future Trends of Colorectal Cancer Treatment: Exploring Advances in Immunotherapy

Cancer of the colon and rectum (CRC) has been identified among the three most prevalent types of cancer and cancer-related deaths for both sexes. Even though significant progress in surgical and chemotherapeutic techniques has markedly improved disease-free and overall survival rates in contrast to those three decades ago, recent years have seen a stagnation in these improvements. This underscores the need for new therapies aiming to augment patient outcomes. A number of emerging strategies, such as immune checkpoint inhibitors (ICIs) and adoptive cell therapy (ACT), have exhibited promising outcomes not only in preclinical but also in clinical settings. Additionally, a thorough appreciation of the underlying biology has expanded the scope of research into potential therapeutic interventions. For instance, the pivotal role of altered telomere length in early CRC carcinogenesis, leading to chromosomal instability and telomere dysfunction, presents a promising avenue for future treatments. Thus, this review explores the advancements in CRC immunotherapy and telomere-targeted therapies, examining potential synergies and how these novel treatment modalities intersect to potentially enhance each other's efficacy, paving the way for promising future therapeutic advancements.

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.

Shorter telomere length increases the risk of lymphocyte immunodeficiency: A Mendelian randomization study

BACKGROUND

For a long time, the prevailing viewpoint suggests that shorter telomere contribute to chromosomal instability, which is a shared characteristic of both aging and cancer. The newest research presented that T cell immune deficiency rather than chromosome instability predisposes patients with short telomere syndromes to some cancers. However, the relationship between genetically determined telomere length (TL) and immune cells remains unclear.

METHODS

The two-sample Mendelian randomization analysis was conducted to elucidate the potential causal relationship. The genetic data of TL and immune cells were obtained from the Genome-Wide Association Study. The inverse variance weighted (IVW) method was used to estimate the effects primarily and another four methods were as a supplement. Sensitivity analysis was used to test the results.

RESULTS

The IVW method showed a significant correlation between TL and the percentage of T cells in lymphocytes (odds ratio [OR]: 1.222, 95% confidence interval [CI]: 1.014-1.472, p = .035), indicating that shorter TL significantly increases the risk of low T cell percentage. Further analysis of T cell subsets indicated that shorter TL may primarily lead to a lower percentage of Natural Killer T cells (OR: 1.574, 95% CI: 1.281-1.935, p < .001). Analysis of B cell subsets revealed that shorter TL may be associated with a higher percentage of Naive-mature B cells, and a lower percentage of Memory B cells. And the sensitivity analysis indicated the validity and robustness of our findings.

CONCLUSION

In summary, our findings suggest that shorter TL may be associated with a decline in the percentage of T cell, as well as impediments in the differentiation of B cell, consequently leading to the onset of immunosenescence and immunodeficiency. The relevant mechanisms and potential therapeutic avenues still need further investigation.

Gender-specific associations between mixture of polycyclic aromatic hydrocarbons and telomere length

Evidence shows the relationships of individual environmental PAHs by their urinary metabolites with relative telomere length (RTL), which may be affected by biological gender differences. Since plasma parent PAHs are not metabolized, it may reflect human exposure to PAHs more realistically in daily life. Thus, exploring joint associations between plasma parent PAHs and RTL is urgent, which may identify the major contributor to its adverse effect. In this study, 2577 participants were obtained from the Henan Rural Cohort. The level of PAHs in blood samples was detected by gas chromatography coupled with tandem mass spectrometry. RTL in blood samples was detected by quantitative polymerase chain reaction. Generalized linear models or quantile g-computation were performed to evaluate the associations between the individual or a mixture of PAHs and RTL. Results from generalized linear models showed that each unit increment in BghiP value corresponded to a 0.098 (95%CI: 0.067, 0.129) increment in RTL for men; each unit increment in BaP, BghiP and Flu value corresponded to a 0.041 (95%CI: 0.014, 0.068), 0.081 (95%CI: 0.055, 0.107) and 0.016 (95%CI: 0.005, 0.027) increment in RTL for women. Results from quantile-g computation revealed that each one-quantile increment in the mixture of 10 PAHs corresponded to a 0.057 (95%CI: 0.021, 0.094) and 0.047 (95%CI: 0.003, 0.091) increment in RTL values of women and men, but these associations were mainly ascribed to three PAHs for women (BaP, Flu and BghiP) and men (BaP, BghiP and Pyr), respectively. Similar results were found in smoking men and cooking women without smoking. Our study found that exposure to 10 PAHs mixture was positively associated with RTL across gender, mainly attributed to Flu, BaP and BghiP, implicating that gender-specific associations may be ascribed to tobacco and cooking smoke pollution. The findings provided clues for effective measures to control PAHs pollutants-related aging disease.Clinical trial registration The Henan Rural Cohort Study has been registered at the Chinese Clinical Trial Register (Registration number: ChiCTR-OOC-15006699). Date of registration: 06 July 2015. http://www.chictr.org.cn/showproj.aspx?proj=11375 .

Understanding the health effects of caregiving stress: New directions in molecular aging

Dementia caregiving has been linked to multiple health risks, including infectious illness, depression, anxiety, immune dysregulation, weakened vaccine responses, slow wound healing, hypertension, cardiovascular disease, metabolic syndrome, diabetes, frailty, cognitive decline, and reduced structural and functional integrity of the brain. The sustained overproduction of proinflammatory cytokines is a key pathway behind many of these risks. However, contrasting findings suggest that some forms of caregiving may have beneficial effects, such as maintaining caregivers' health and providing a sense of meaning and purpose which, in turn, may contribute to lower rates of functional decline and mortality. The current review synthesizes these disparate literatures, identifies methodological sources of discrepancy, and integrates caregiver research with work on aging biomarkers to propose a research agenda that traces the mechanistic pathways of caregivers' health trajectories with a focus on the unique stressors facing spousal caregivers as compared to other informal caregivers. Combined with a focus on psychosocial moderators and mechanisms, studies using state-of-the-art molecular aging biomarkers such as telomere length, p16INK4a, and epigenetic age could help to reconcile mixed literature on caregiving's sequelae by determining whether and under what conditions caregiving-related experiences contribute to faster aging, in part through inflammatory biology. The biomarkers predict morbidity and mortality, and each contributes non-redundant information about age-related molecular changes -together painting a more complete picture of biological aging. Indeed, assessing changes in these biopsychosocial mechanisms over time would help to clarify the dynamic relationships between caregiving experiences, psychological states, immune function, and aging.

Big data analysis identified a telomere-related signature predicting the prognosis and drug sensitivity in lung adenocarcinoma

Telomeres exert a critical role in chromosome stability and aberrant regulation of telomerase may result in telomeres dysfunction and genomic instability, which are involved in the occurrence of cancers. However, limited studies have been performed to fully clarify the immune infiltration and clinical significance of telomeres-related genes (TRGs) in lung adenocarcinoma (LUAD). The number of clusters of LUAD was determined by consensus clustering analysis. The prognostic signature was constructed and verified using TCGA and GSE42127 dataset with Least Absolute Shrinkage and Selection Operator cox regression analysis. The correlation between different clusters and risk-score and drug therapy response was analyzed using TIDE and IMvigor210 dataset. Using several miRNA and lncRNA related databases, we constructed a lncRNA-miRNA-mRNA regulatory axis. We identified 2 telomeres-related clusters in LUAD, which had distinct differences in prognostic stratification, TMB score, TIDE score, immune characteristics and signal pathways and biological effects. A prognostic model was developed based on 21 TRGs, which had a better performance in risk stratification and prognosis prediction compared with other established models. TRGs-based risk score could serve as an independent risk factor for LUAD. Survival prediction nomogram was also developed to promote the clinical use of TRGs risk score. Moreover, LUAD patients with high risk score had a high TMB score, low TIDE score and IC50 value of common drugs, suggesting that high risk score group might benefit from receiving immunotherapy, chemotherapy and target therapy. We also developed a lncRNA KCNQ1QT1/miR-296-5p/PLK1 regulatory axis. Our study identified 2 telomeres-related clusters and a prognostic model in LUAD, which could be helpful for risk stratification, prognosis prediction and treatment approach selection.

Association of Telomere Length with Cognitive Impairment

Telomere attrition is attributed to Alzheimer's disease (AD), major depressive disorder, stress levels, physical inactivity, short sleep duration, and reduced educational abilities. In this article, we tried to assess the association between the telomere length in peripheral blood leukocytes and level of cognitive impairment and its dependence on age and sex. Healthy subjects and patients with amnestic mild cognitive impairment (aMCI) and different AD stages were recruited in the study. All patients were assessed by the same standard diagnostic procedure, including neurological examination-Mini-Mental State Examination (MMSE). Blood samples from 66 subjects (18 men and 48 women, mean age 71.2 ± 0.56 years) were collected for DNA extraction from peripheral mononuclear cells (PBMC). Relative telomere length (RTL) was measured by monochrome multiplex polymerase chain reaction. The data obtained in the study indicate that RTL in PBMCs has a statistically significant association with MMSE score (p < 0.02). Moreover, the sex-specific difference was observed for the association between telomere length and various parameters of MMSE. Also, it has been found that a decrease in RTL by one unit is associated with an increase in the odds to get AD at a ratio of 2.54 (95% CI, 1.25 to 5.17). The results obtained in this research are in coherence with other studies that telomere length may be a valuable biomarker of cognitive decline. However, the potential need for longitudinal studies of telomere length, in order to estimate the influence of hereditary and environmental factors, remains.

Association between leukocyte telomere length and COVID-19 severity

Background

Inter-individual variations in the clinical manifestations of SARS-CoV-2 infection are among the challenging features of COVID-19. The known role of telomeres in cell proliferation and immune competency highlights their possible function in infectious diseases. Variability in telomere length is an invaluable parameter in the heterogeneity of the clinical presentation of diseases.

Result

In this study, our aim was to investigate the possible association between leukocyte telomere length (LTL) and COVID-19 severity. LTL was measured in 100 patients with moderate and severe forms of COVID-19 using the quantitative PCR (q-PCR) method. Statistical analysis confirmed a strong inverse correlation between relative LTL and COVID-19 severity.

Conclusions

These findings suggest that LTL can be a useful parameter for predicting disease severity in patients, as individuals with short telomeres may have a higher risk of developing severe COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43042-023-00415-z.

Causes and consequences of telomere lengthening in a wild vertebrate population

Telomeres have been advocated to be important markers of biological age in evolutionary and ecological studies. Telomeres usually shorten with age and shortening is frequently associated with environmental stressors and increased subsequent mortality. Telomere lengthening - an apparent increase in telomere length between repeated samples from the same individual - also occurs. However, the exact circumstances, and consequences, of telomere lengthening are poorly understood. Using longitudinal data from the Seychelles warbler (Acrocephalus sechellensis), we tested whether telomere lengthening - which occurs in adults of this species - is associated with specific stressors (reproductive effort, food availability, malarial infection and cooperative breeding) and predicts subsequent survival. In females, telomere shortening was observed under greater stress (i.e., low food availability, malaria infection), while telomere lengthening was observed in females experiencing lower stress (i.e., high food availability, assisted by helpers, without malaria). The telomere dynamics of males were not associated with the key stressors tested. These results indicate that, at least for females, telomere lengthening occurs in circumstances more conducive to self-maintenance. Importantly, both females and males with lengthened telomeres had improved subsequent survival relative to individuals that displayed unchanged, or shortened, telomeres - indicating that telomere lengthening is associated with individual fitness. These results demonstrate that telomere dynamics are bidirectionally responsive to the level of stress that an individual faces, but may poorly reflect the accumulation of stress over an individuals lifetime.

Transmissible cancer and longitudinal telomere dynamics in Tasmanian devils (Sarcophilus harrisii)

A plethora of intrinsic and environmental factors have been shown to influence the length of telomeres, the protector of chromosome ends. Despite the growing interest in infection-telomere interactions, there is very limited knowledge on how transmissible cancers influence telomere maintenance. An emblematic example of transmissible cancer occurs in the Tasmanian devil (Sarcophilus harrisii), whose populations have been dramatically reduced by infectious cancer cells. To investigate associations between telomere dynamics and the transmissible cancer, we used longitudinal data from a Tasmanian devil population that has been exposed to the disease for over 15 years. We detected substantial temporal variation in individual telomere length (TL), and a positive significant association between TL and age, as well as a marginally significant trend for devils with devil facial tumour disease (DFTD) having longer telomeres. A proportional hazard analysis yielded no significant effect of TL on the development of DFTD. Like previous studies, we show the complexity that TL dynamics may exhibit across the lifetime of organisms. Our work highlights the importance of long-term longitudinal sampling for understanding the effects of wildlife diseases on TL.

Shortened Telomere Length in Sputum Cells of Bronchiectasis Patients is Associated with Dysfunctional Inflammatory Pathways

Telomere attrition is an established ageing biomarker and shorter peripheral blood leukocyte telomere length has been associated with increased risks of respiratory diseases. However, whether telomere length in disease-relevant sputum immune cells of chronic respiratory disease patients is shortened and which pathways are dysfunctional are not clear. Here we measured telomere length from sputum samples of bronchiectasis and asthmatic subjects and determined that telomere length in sputum of bronchiectasis subjects was significantly shorter (Beta =  - 1.167, P_Adj = 2.75 × 10^-4). We further performed global gene expression analysis and identified genes involved in processes such as NLRP3 inflammasome activation and regulation of adaptive immune cells when bronchiectasis sputum telomere length was shortened. Our study provides insights on dysfunctions related to shortened telomere length in sputum immune cells of bronchiectasis patients.

The association of telomere maintenance and TERT expression with susceptibility to human papillomavirus infection in cervical epithelium

The role of telomerase reverse transcriptase (TERT) induction and telomere maintenance in carcinogenesis including cervical cancer (CC) pathogenesis has been well established. However, it remains unclear whether they affect infection of high-risk human papillomavirus (hrHPV), an initiating event for CC development. Similarly, genetic variants at the TERT locus are shown to be associated with susceptibility to CC, but it is unclear whether these SNPs modify the risk for cervical HPV infection. Here we show that in CC-derived HeLa cells, TERT overexpression inhibits, while its depletion upregulates expression of Syndecan-1 (SDC-1), a key component for HPV entry receptors. The TCGA cohort of CC analyses reveals an inverse correlation between TERT and SDC-1 expression (R = -0.23, P = 0.001). We further recruited 1330 females (520 non-HPV and 810 hrHPV-infected) without CC or high-grade cervical intraepithelial neoplasia to analyze telomeres in cervical epithelial cells and SNPs at rs2736098, rs2736100 and rs2736108, previously identified TERT SNPs for CC risk. Non-infected females exhibited age-related telomere shortening in cervical epithelial cells and their telomeres were significantly longer than those in hrHPV-infected group (1.31 ± 0.62 vs 1.19 ± 0.48, P < 0.001). There were no differences in rs2736098 and rs2736100 genotypes, but non-infected individuals had significantly a higher C-allele frequency (associated with higher TERT expression) while lower T-allele levels at rs2736108 compared with those in the hrHPV group (P = 0.020). Collectively, appropriate telomere maintenance and TERT expression in normal cervical cells may prevent CC by modulating hrHPV infection predisposition, although they are required for CC development and progression.

Telomere length as a biomarker of aging and diseases

As research related to healthspan and lifespan has become a hot topic, the necessity for a reliable and practical biomarker of aging (BoA), which can provide information about mortality and morbidity risk, along with remaining life expectancy, has increased. The chromosome terminus non-coding protective structure that prevents genomic instability is called a telomere. The continual shortening of telomeres, which affects their structure as well as function, is a hallmark of agedness. The aforementioned process is a potential cause of age-related diseases (ARDs), leading to a bad prognosis and a low survival rate, which compromise health and longevity. Hence, studies scrutinizing the BoAs often include telomere length (TL) as a prospective candidate. The results of these studies suggest that TL measurement can only provide an approximate appraisal of the aging rate, and its implementation into clinical practice and routine use as a BoA has many limitations and challenges. Nevertheless, measuring TL while determining other biomarkers can be used to assess biological age. This review focuses on the importance of telomeres in health, senescence, and diseases, as well as on summarizing the results and conclusions of previous studies evaluating TL as a potential BoA.

Resolution of recurrent pediatric acute liver failure with liver transplantation in a patient with NBAS mutation

BACKGROUND

Pediatric acute liver failure (PALF) remains an enigmatic process of rapid end-organ dysfunction associated with a variety of pathologic conditions though the predominant cause is indeterminate. A growing body of research has identified mutations in the NBAS gene to be associated with recurrent acute liver failure and multi-systemic disease including short stature, skeletal dysplasia, facial dysmorphism, immunologic abnormalities, and Pelger-Huët anomaly.

METHODS AND RESULTS

Here, we describe a 4-year-old girl who presented with dehydration in the setting of acute gastroenteritis and fever but went on to develop PALF on day 2 of hospitalization. She clinically recovered with supportive measures, but after discharge, had at least 2 additional episodes of PALF. Ultimately, she underwent liver transplant and her recurrent episodes of PALF did not recur throughout a 6-year follow-up period. Whole-exome sequencing post-liver transplant initially revealed two variants of uncertain significance in the NBAS gene. Parental studies confirmed the c.1549C > T(p.R517C; now likely pathogenic) variant from her mother and a novel c.4646T > C(p.L1549P) variant from her father. In silico analyses predicted these variants to have a deleterious effect on protein function. Consistent with previously characterized NBAS mutation-associated disease (NMAD), our patient demonstrated the following features: progeroid facial features, hypoplasia of the 12th ribs, Pelger-Huët anomaly on peripheral blood smear, and abnormal B and NK cell function.

CONCLUSION

Altogether, we describe a novel pathogenic variant in the NBAS gene of a patient with NMAD and report the resolution of recurrent PALF secondary to NMAD following liver transplantation.

Telomeres, species differences, and unusual telomeres in vertebrates: presenting challenges and opportunities to understanding telomere dynamics

There has been increasing interest in the use of telomeres as biomarkers of stress, cellular ageing and life-histories. However, the telomere landscape is a diverse feature, with noticeable differences between species, a fact which is highlighted by the unusual telomeres of various vertebrate organisms. We broadly review differences in telomere dynamics among vertebrates, and emphasize the need to understand more about telomere processes and trends across species. As part of these species differences, we review unusual telomeres in vertebrates. This includes mega-telomeres, which are present across a diverse set of organisms, but also focusing on the unusual telomeres traits of marsupials and monotremes, which have seen little to no prior discussion, yet uniquely stand out from other unusual telomere features discovered thus far. Due to the presence of at least two unique telomere features in the marsupial family Dasyuridae, as well as to the presence of physiological strategies semelparity and torpor, which have implications for telomere life-histories in these species, we suggest that this family has a very large potential to uncover novel information on telomere evolution and dynamics.

Telomere length and outcome of treatment for pulmonary tuberculosis in a gold mining community

Telomere length (TL) is a marker of ageing and mitochondrial DNA (mtDNA) is an early marker of inflammation caused by oxidative stress. We determined TL and mtDNA content among active pulmonary tuberculosis (PTB) patients to assess if these cellular biomarkers differed between artisanal miners and non-miners, and to assess if they were predictive of treatment outcome. We conducted a prospective cohort study from August 2018 to May 2019 involving newly diagnosed PTB patients at three outpatient TB clinics in a rural Democratic Republic of Congo. We measured relative TL and mtDNA content in peripheral blood leukocytes (at inclusion) via qPCR and assessed their association with PTB treatment outcome. We included 129 patients (85 miners and 44 non-miners) with PTB (median age 40 years; range 5-71 years, 22% HIV-coinfected). For each increase in year and HIV-coinfection, TL shortened by - 0.85% (- 0.19 to - 0.52) (p ≤ 0.0001) and - 14% (- 28.22 to - 1.79) (p = 0.02) respectively. Independent of these covariates, patients with longer TL were more likely to have successful TB treatment [adjusted hazard ratio; 95% CI 1.27 for a doubling of leucocyte telomere length at baseline; 1.05-1.44] than patients with a shorter TL. Blood mtDNA content was not predictive for PTB outcome. For a given chronological age, PTB patients with longer telomeres at time of diagnosis were more likely to have successful PTB treatment outcome.

COVID-19 Risk: Clinical Tools for Assessing and Personalizing Immunity

Researchers and clinicians all over the world are struggling to bring the spread of SARS-CoV-2 under control. Whether we refer to COVID-19 as a pandemic (a widely used word) or a syndemic (a new emerging term), we now know that specific immunotypes have been linked to both risk to infection and presentation of this disease. Application of assessment tools that support a fuller understanding of individual immune system status is next-level care that providers must prepare for and deliver. Commonly used biometric devices already gather data that can be relevant and useful to a phenotypic evaluation of immune function. These variables include pulse rate, blood oxygenation, sleep cycles, respiration rate, heart rate variability, continuous blood glucose monitoring, and ambulatory blood pressure. When coupled with traditional blood analytes and measurements of nutrient status, a more complete picture of immunological function may be revealed. Innovative questionnaires and algorithms can also be helpful additions to a clinician's toolkit. In a therapeutic relationship between provider and patient, this approach may lead to options for personalized immune intervention using diet, medical nutrition, and lifestyle medicine.

The Association Between Leukocyte Telomere Length and Cognitive Performance Among the American Elderly

Background

Age-related cognitive decline begins in middle age and persists with age. Leukocyte telomere length (LTL) decreases with age and is enhanced by inflammation and oxidative stress. However, whether shorter LTL correlates with cognitive decline remains controversial.

Aims

We aimed to investigate the relationship between LTL and cognitive decline in the American elderly.

Methods

We used data from the 1999 to 2002 U.S. National Health and Nutrition Examination Survey (NHANES). We included participants aged 65–80 with available data on LTL and cognitive assessments. The cognitive function assessment used the digit symbol substitution test (DSST). We applied multivariate modeling to estimate the association between LTL and cognitive performance. Additionally, to ensure robust data analysis, we converted LTL into categorical variables through quartile and then calculated the P for trend.

Results

After adjusting for age, cardiovascular disease (CAD) score, gender, race, body mass index (BMI), and educational level, LTL showed a positive correlation with DSST score (odds ratio [OR] 3.47 [0.14, 6.79], P = 0.04). Additionally, to further quantify the LTL–DSST interaction, we found a similar trend when LTL was regarded as a categorical variable (quartile) (P for trend = 0.03).

Conclusion

LTL was associated with cognitive capabilities among the elderly, implying that LTL might be a biomarker of cognitive aging.

Health Disparities in COVID-19: Addressing the Role of Social Determinants of Health in Immune System Dysfunction to Turn the Tide

It is evident that health disparities exist during the COVID-19 pandemic, a pandemic caused by the novel coronavirus SARS-CoV-2. Underlying reasons for COVID-19 health disparities are multi-factorial. However, social determinants, including those regarding socioeconomic status, social inequalities, health behaviors, and stress, may have implications on these disparities. Exposure to one or more of these social determinants is associated with heightened inflammatory responses, particularly increases in the cytokine interleukin-6 (IL-6), as well as immune system dysfunction. Thus, an amplified effect during COVID-19 could occur, potentially resulting in vulnerable patients experiencing an intensified cytokine storm due to a hyperactive and dysfunctional immune response. Further understanding how social determinants play a mechanistic role in COVID-19 disparities could potentially help reduce health disparities overall and in future pandemics.

Telomere Length is a Susceptibility Marker for Tasmanian Devil Facial Tumor Disease

Telomeres protect chromosomes from degradation during cellular replication. In humans, it is well-documented that excessive telomere degradation is one mechanism by which cells can become cancerous. Increasing evidence from wildlife studies suggests that telomere length is positively correlated with survival and health and negatively correlated with disease infection intensity. The recently emerged devil facial tumor disease (DFTD) has led to dramatic and rapid population declines of the Tasmanian devil throughout its geographic range. Here, we tested the hypothesis that susceptibility to DFTD is negatively correlated with telomere length in devils across three populations with different infection histories. Our findings suggest telomere length is correlated with DFTD resistance in three ways. First, devils from a population with the slowest recorded increase in DFTD prevalence (West Pencil Pine) have significantly longer telomeres than those from two populations with rapid and exponential increases in prevalence (Freycinet and Narawantapu). Second, using extensive mark-recapture data obtained from a long-term demographic study, we found that individuals with relatively long telomeres tend to be infected at a significantly later age than those with shorter telomeres. Third, a hazard model showed devils with longer telomeres tended to become infected at a lower rate than those with shorter telomeres. This research provides a rare study of telomere length variation and its association with disease in a wildlife population. Our results suggest that telomere length may be a reliable marker of susceptibility to DFTD and assist with future management of this endangered species.

The telomerase gene polymorphisms, but not telomere length, increase susceptibility to primary glomerulonephritis/end stage renal diseases in females

Background

Primary glomerulonephritis (GN) is the leading cause of chronic kidney disease (CKD) and frequently progresses into end stage renal diseases (ESRDs). Shorter leukocyte telomere length (LTL) has been implicated in the CKD susceptibility and diminished kidney function, however, it is unclear whether the variants in telomerase genes contribute to risk to GN/CKD/ESRD. Here we address this issue by determining their association with the genetic variants of rs12696304 at the telomerase RNA component (TERC) and rs2736100 at the telomerase reverse transcriptase (TERT) loci.

Methods

The study includes 769 patients (243 primary GN-derived CKD and 526 ESRD cases) and sex-/age-matched healthy controls. Genomic DNA was extracted from peripheral blood of both controls and patients. Genotyping of rs12696304 and rs2736100 variants was carried out using PCR-based assays. Leukocyte telomere length (LTL) was determined using quantitative PCR (qPCR).

Results

A significantly higher frequency of TERC rs12696304 G allele was observed in patients and associated with increased disease risk (C vs G: OR = 1.334, 95% CI 1.112–1.586, P = 0.001; CC + GC vs GG: OR = 1.334, 95% CI 1.122–1.586, P = 0.001). Further analyses showed that such significant differences were only present between female controls and patients (C vs G: OR = 1.483, 95% CI 1.140–1.929, P = 0.003; CC + GC vs CC: OR = 1.692, 95% CI 1.202–2.383, P = 0.003), but not males. There were no differences in rs2736100 variants between controls and patients, but female ESRD patients carried significantly higher C allele frequencies than did female controls (A vs C: OR = 1.306, 95% CI 1.005–1.698, P = 0.046; AA vs CC: OR = 1.781, 95% CI 1.033–3.070, P = 0.037). There was no difference in LTL between controls and patients.

Conclusions

Our results reveal that the TERC rs12696304 and TERT rs2736100 polymorphisms, but not LTL per se, contribute to GN/CDK/ESRD risk.

Association between Leucocyte Telomere Length and Risk of Hearing Loss in the General Population: A Case-Control Study in Zhejiang Province, China

Limited studies have assessed the relation between telomere length and risk of hearing loss; moreover, they have reported equivocal associations. In the first case-control study, the subjects were chosen from the general population of Zhejiang province in order to assess the association between leucocyte telomere length and risk of hearing loss from 2016 to 2018. A total of 817 cases (55.93 ± 8.99 years) and 817 age-, sex- and residential city-matched controls (55.91 ± 9.03 years) were included for analysis. In the multivariable models, individuals in the top quartile of relative telomere length (RTL) had an odds ratio (OR) for hearing loss of 0.53 (95% confidence intervals [CI], 0.38–0.74) compared to those in the bottom quartile, and specifically, the OR was 0.45 (95% CI, 0.28–0.73) in females. In females, the risk of hearing loss decreased by 46% as RTL doubling increased; the standard deviation of RTL was associated with a 29% decrease in hearing loss risk. Additional analysis showed significant difference between participants in the female mild hearing loss group and corresponding controls. These results suggest that telomere length is associated with hearing loss in the general population, particularly in females with mild hearing loss. Telomere length might be a potential predictive biomarker of hearing loss at early stage.

Shorter Leukocyte Telomere Length coupled with lower expression of Telomerase Genes in patients with Essential Hypertension

Background: The essential hypertension (EH) pathophysiology remains poorly understood. Many studies indicate that reduced leukocyte telomere length (LTL) is involved in the EH pathogenesis, however, the direct analysis of arterial telomere length (ATL) from EH patients and normotensive individuals did not show a difference. To address these discrepant observations between LTL and ATL, we performed comprehensive analyses of LTL, telomerase gene expression and their genetic variants in healthy normotensive controls and EH patients. Methods: Sex-matched 206 EH patients and equal numbers of healthy controls were recruited. LTL, and the expression of two key telomerase components, telomerase reverse transcriptase (TERT) and internal RNA template (TERC) were determined using qPCR. Genetic variants of rs2736100 at the TERT and rs12696304 at the TERC loci were determined using TaqMan genotyping kits. Results: LTL was significantly shorter in EH patients than in their normotensive controls (0.96 ± 0.52 vs 1.19 ± 0.58, P = 0.001). Moreover, TERT and TERC expression in patients' leukocytes were substantially lower compare to that in healthy controls (TERT, 0.98 ± 0.98 vs 1.76 ± 1.75, P = 0.003; TERC, 1.26 ± 1.62 vs 4.69 ± 3.61, P < 0.001). However, there were no differences in the genetic variants of rs2736100 and rs12696304 between patient and control groups. Conclusions: EH patients have significantly shorter LTL, which may result from defective TERT and TERC expression in leukocytes. Collectively, lower telomerase expression contributes to shorter LTL observed in EH patients, and telomerase activators may be considered for EH therapy.

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.

Age-associated telomere shortening in Thoroughbred horses

Telomeres are genetically conserved repetitive terminal DNA that protect against genomic instability and shorten with ageing. Here, we reveal the leukocyte telomere length of Equus caballus by measuring terminal restriction fragments (TRFs) using Southern Blot analysis in a cohort of 43 Thoroughbred horses (age: 24 h-25 years). Heterogeneous TRFs were observed in each animal and large inter-animal variation in mean TRF was observed (range: 10.5-18.7 kbp). Mean TRFs were inversely correlated with age (r = -0.47). The estimated yearly rate of telomere attrition was 134 bp. Horses should be considered as an alternative animal model to investigate environmental and lifestyle factors that regulate telomeres and promote healthy ageing.

Telomeres in neurological disorders

Ever since their discovery, the telomeres and the telomerase have been topics of intensive research, first as a mechanism of cellular aging and later as an indicator of health and diseases in humans. By protecting the chromosome ends, the telomeres play a vital role in preserving the information in our genome. Telomeres shorten with age and the rate of telomere erosion provides insight into the proliferation history of cells. The pace of telomere attrition is known to increase at the onset of several pathological conditions. Telomere shortening has been emerging as a potential contributor in the pathogenesis of several neurological disorders including autism spectrum disorders (ASD), schizophrenia, Alzheimer's disease (AD), Parkinson's disease (PD) and depression. The rate of telomere attrition in the brain is slower than that of other tissues owing to the low rate of cell proliferation in brain. Telomere maintenance is crucial for the functioning of stem cells in brain. Taking together the studies on telomere attrition in various neurological disorders, an association between telomere shortening and disease status has been demonstrated in schizophrenia, AD and depression, in spite of a few negative reports. But, studies in ASD and PD have failed to produce conclusive results. The cause-effect relationship between TL and neurological disorders is yet to be elucidated. The factors responsible for telomere erosion, which have also been implicated in the pathogenesis of neurological disorders, need to be explored in detail. Telomerase activation is now being considered as a potential therapeutic strategy for neurological disorders.

Experimental manipulation of telomere length: does it reveal a corner-stone role for telomerase in the natural variability of individual fitness?

Telomeres, the non-coding ends of linear chromosomes, are thought to be an important mechanism of individual variability in performance. Research suggests that longer telomeres are indicative of better health and increased fitness; however, many of these data are correlational and whether these effects are causal are poorly understood. Experimental tests are emerging in medical and laboratory-based studies, but these types of experiments are rare in natural populations, which precludes conclusions at an evolutionary level. At the crossroads between telomere length and fitness is telomerase, an enzyme that can lengthen telomeres. Experimental modulation of telomerase activity is a powerful tool to manipulate telomere length, and to look at the covariation of telomerase, telomeres and individual life-history traits. Here, we review studies that manipulate telomerase activity in laboratory conditions and emphasize the associated physiological and fitness consequences. We then discuss how telomerase's impact on ageing may go beyond telomere maintenance. Based on this overview, we then propose several research avenues for future studies to explore how individual variability in health, reproduction and survival may have coevolved with different patterns of telomerase activity and expression. Such knowledge is of prime importance to fully understand the role that telomere dynamics play in the evolution of animal ageing.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.

Telomere length and survival in primary cutaneous melanoma patients

Telomere repeats at chromosomal ends, critical to genomic integrity, undergo age-dependent attrition. Telomere length, a polygenic trait, has been associated with risk of several disorders including cancers. In contrast to association of long telomeres with increased risk of several cancers, including melanoma, emerging reports suggest that short telomeres predict poor survival in patients with different cancers. In this study based on 1019 stage I and II cutaneous melanoma patients, we show an association between the patients with short telomeres and poor melanoma-specific survival (HR 2.05, 95% CI 1.33-3.16) compared to patients with long telomeres. Due to inverse correlation between age and telomere length (r -0.19, P < 0.0001), we stratified the patients into quantiles based on age at diagnosis and also carried out age-matched analysis. The effect of short telomeres on survival was determined by using multivariate Cox regression that included composite genetic risk score computed from genotyping of the patients for telomere-length associated polymorphisms. The effect of decreased telomere length on poor melanoma-specific survival was particularly strong in patients within the age quantile below 30 years (HR 3.82, 95% CI 1.10-13.30) and between 30-40 years (HR 2.69, 95% CI 1.03-7.03). Our study shows that in contrast to increased melanoma risk associated with increased telomere length, decreased telomere length predicts poor survival in melanoma subgroups.

Prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances affects leukocyte telomere length in female newborns

Evidence has shown that leukocyte telomere length (LTL) at birth is related to the susceptibility to various diseases in later life and the setting of newborn LTL is influenced by the intrauterine environment. Perfluoroalkyl and polyfluoroalkyl substances (PFASs), as a kind of persistent organic pollutants, are commonly used in commercial and domestic applications and are capable of crossing the maternal-fetal barrier during pregnancy. We hypothesized that intrauterine exposure to PFASs may affect fetal LTL by increasing oxidative stress. To verify this hypothesis, LTL, concentrations of PFASs and reactive oxygen species (ROS) were measured in umbilical cord blood of 581 newborns from a prospective cohort. Our results showed that there were interactions between PFOS/PFDA and sex on LTL and ROS. The LTL was significantly shorter (0.926 ± 0.053 vs 0.945 ± 0.054, P = .023 for PFOS; 0.919 ± 0.063 vs 0.940 ± 0.059, P = .011 for PFDA) and the ROS levels were extremely higher (252.9 ± 60.5 [M] vs 233.5 ± 53.6 [M], P = .031 for PFOS; 255.2 ± 62.9 [M] vs 232.9 ± 58.3 [M], P = .011 for PFDA) in the female newborns whose PFOS or PFDA concentrations fell in the upmost quartile compared with those in the lowest quartile after adjusting for potential confounders. ROS levels were inversely associated with LTL in female newborns (β = -1.42 × 10^-4, P = .022). 13% of the effect of PFOS on female LTL was mediated through ROS approximately by the mediation analyses. However, in male newborns, no relationships among PFASs, ROS and LTL were observed. Our findings suggest a "programming" role of PFASs on fetal telomere biology system in females in intrauterine stage.

Association of TERT polymorphisms with chronic hepatitis B in a Chinese Han population

In this study, we investigated the association between the polymorphisms of telomerase reverse transcriptase (TERT) gene and the risk of chronic hepatitis B (CHB) in a Chinese Han population. Four single nucleotide polymorphisms (SNPs) in TERT (rs10069690, rs2242652, rs2853677 and rs2853676) were genotyped from 224 CHB patients and 300 healthy controls using the Sequenom Mass-ARRAY platform. We used genetic model, haplotype analyses, chi-square test, logistic regression analysis to evaluate the association between SNPs and CHB risk. The relative risk was estimated by odd ratios (ORs) and 95% confidence intervals (CIs). We found that rs10069690 was significantly associated with an increased CHB risk in the dominant model (adjusted OR = 1.70, 95% CI: 1.06–2.71, P = 0.031) and additive model (adjusted OR = 1.62, 95% CI: 1.09–2.41, P = 0.018). The haplotype “TA” (rs10069690 and rs2242652) was found to be associated with an increased risk of CHB (adjusted OR = 1.58, 95% CI: 1.05–2.38, P = 0.027). Our results suggested potential genetic contributes for TERT in CHB development in a Chinese Han population. Future functional and association studies with larger sample sizes are required to confirm these findings.

Current perspectives on the role of CD8+ T cells in systemic sclerosis

Despite long-standing recognition of the importance of T cells in systemic sclerosis (SSc; scleroderma), the role of CD8⁺ T cells in disease pathogenesis has not been well studied. Our work has shown that over-production of the pro-fibrotic cytokine IL-13 by peripheral blood effector/memory CD8⁺ T cells is critical for predisposing patients to more severe forms of cutaneous fibrosis. Moreover, IL-13-producing CD8⁺ T cells induce a pro-fibrotic phenotype in normal and SSc dermal fibroblasts, and exhibit a strong cytotoxic activity ex vivo. We also found that CD8⁺ T cells are predominantly abundant in the skin lesions of patients in the early stages of diffuse cutaneous (dc)SSc compare to late-stage disease patients. Isolation of CD8⁺ T cells from the lesional skin of early active dcSSc patients, established that they are skin-resident, express cytolytic molecules and co-express extremely high levels of IL-13 and IFNγ. Other recent studies corroborate these findings and together strongly suggest that CD8⁺ T cells contribute to SSc pathogenesis through the production of high levels of cytokines with pro-inflammatory and pro-fibrotic function as well as by exhibiting a cytotoxic activity.

Association of leukocyte telomere length and the risk of age-related hearing impairment in Chinese Hans

Age-related hearing loss (ARHI) is the most common sensory disorder in the elderly. Although telomere attrition has been shown as a determinant in the pathobiology of various age-related diseases, it remains unknown whether telomere length is associated with ARHI. We hypothesized that decreased leukocyte telomere length (LTL) increased the risk of ARHI. Thus, we measured LTL of 666 ARHI and 43 controls by an established quantitative PCR technique. Four audiogram shape subtypes of ARHI, including “flat shape (FL)”, “2–4 kHz abrupt loss (AL) shape”, “8 kHz dip (8D) shape” and “sloping shape (SL)” could be identified among the cases using K-means cluster analysis. Longer LTL was associated with the reduced incidence of ARHI (adjusted OR = 0.550, 95% CI: 0.420–0.721, P < 0.0001 for all the ARHI; 0.498, 0.318–0.780, P = 0.0023 for FL subgroup; 0.428, 0.292–0.628, P < 0.0001 for AL subgroup; 0.552, 0.399–0.764, P = 0.0003 for mSL subgroup). Subjects in the highest tertile of LTL were at less risk for ARHI than those in the lowest and middle tertiles (OR for ARHI: 0.327, 95% CI 0.170–0.629, P = 0.0008). There was a descending trend of LTL as the degree of pure tone threshold average (PTA) aggravated. These results suggest that telomere attrition may be involved in the progression of ARHI.

Telomere Shortening, Inflammatory Cytokines, and Anti-Cytomegalovirus Antibody Follow Distinct Age-Associated Trajectories in Humans

A number of biological parameters have been cited as hallmarks of immune aging. However, it is not clear whether these multiple biological changes are the result of common underlying aging processes and follow correlated trajectories, or whether the patterns of change for multiple parameters vary across individuals and reflect heterogeneity in the aging process. Here, we have studied parameters of immune system aging through longitudinal analysis of telomere length, inflammatory cytokines, and antibody titer to cytomegalovirus (CMV) in 465 subjects ranging in age from 21 to 88 years at the first visit, with an average of 13 years (7-19 years) follow-up. We observed a highly variable rate of change in telomere length of PBMCs with a relatively slow average rate of telomere shortening (-16 bp/year). Similarly, there were significant increases with age in vivo in three inflammation-related cytokines (interferon gamma, IL-6, and IL-10) and in anti-CMV IgG titer, which varied widely across individuals as well. We further observed positive correlative changes among different inflammatory cytokines. However, we did not find significant correlations among the rate of changes in telomere length, inflammatory cytokines, and anti-CMV IgG titers. Our findings thus reveal that age-related trajectories of telomere attrition, elevated circulating inflammatory cytokines, and anti-CMV IgG are independent and that aging individuals do not show a uniform pattern of change in these variables. Immune aging processes are complex and vary across individuals, and the use of multiple biomarkers is essential to evaluation of biological aging of the immune system.

Shorter leukocyte telomere length is associated with higher risk of infections: a prospective study of 75,309 individuals from the general population

In the general population, older age is associated with short leukocyte telomere length and with high risk of infections. In a recent study of allogeneic hematopoietic cell transplantation for severe aplastic anemia, long donor leukocyte telomere length was associated with improved survival in the recipients. These findings suggest that leukocyte telomere length could possibly be a marker of immune competence. Therefore, we tested the hypothesis that shorter leukocyte telomere length is associated with higher risk of infectious disease hospitalization and infection-related death. Relative peripheral blood leukocyte telomere length was measured using quantitative polymerase chain reaction in 75,309 individuals from the general population and the individuals were followed for up to 23 years. During follow up, 9228 individuals were hospitalized with infections and infection-related death occurred in 1508 individuals. Shorter telomere length was associated with higher risk of any infection (hazard ratio 1.05 per standard deviation shorter leukocyte telomere length; 95% confidence interval 1.03–1.07) and pneumonia (1.07; 1.03–1.10) after adjustment for conventional infectious disease risk factors. Corresponding hazard ratios for infection-related death were 1.10 (1.04–1.16) for any infection and 1.11 (1.04–1.19) for pneumonia. Telomere length was not associated with risk of skin infection, urinary tract infection, sepsis, diarrheal disease, endocarditis, meningitis or other infections. In conclusion, our findings indicate that leukocyte telomere length may be a marker of immune competence. Further studies are needed to determine whether risk of infections in allogeneic hematopoietic cell transplantation recipients can be reduced by considering donor leukocyte telomere length when selecting donors.

Association Between the Telomerase rs2736098_TT Genotype and a Lower Risk of Chronic Hepatitis B and Cirrhosis in Chinese Males

OBJECTIVES

Chronic hepatitis B (CHB) is caused by infection of hepatitis B virus (HBV) and liver cirrhosis (LC) is its most common complication. The accumulated evidence indicates a genetic context of HBV infection phenotypes. Here we determine a potential association of CHB/LC with the genetic variant of telomerase reverse transcriptase (TERT), a key player in aging including immune-senescence.

METHODS

The study included 227 Chinese CHB patients and 315 sex/age-matched healthy controls. TERT rs2736098 and rs2736100 genotyping was performed using pre-designed TaqMan SNP genotyping assay kits. Leukocyte telomere length (LTL) was determined using quantitative PCR.

RESULTS

The rs2736098_CT/CC genotypes were significantly associated with risk of CHB compared to the TT one (OR 2.265, 95% CI 1.202-4.269, P=0.015). A similar association was also found in CHB patients with cirrhosis (CT/CC vs TT: OR 2.398, 95% CI 1.168-4.922, P=0.02). Further analyses showed that the rs2736098_TT genotype difference occurred between male controls and patients (P=0.008) and male CT/CC-carriers exhibited highly increased risk of CHB compared to male controls (CT+CC vs TT, OR 3.182, 95% CI 1.350-7.500, P=0.01). There was no difference in the rs2736100 variants between controls and CHB patients. LTL was not different between cases and controls.

CONCLUSIONS

The TERT rs2736098_TT genotype is associated with a lower CHB and LC risk in Chinese males, which may have implications in CHB pathogenesis and prevention.

Impact of Dehydroepiandrosterone Sulfate on Newborn Leukocyte Telomere Length

The newborn setting of leukocyte telomere length (LTL) likely has important implications for telomere dynamics over the lifespan. However, its determinants are poorly understood. Hormones play an important role during pregnancy and delivery. We hypothesized that exposure to hormones may impact the fetal telomere biology system. To test this hypothesis, cortisol, estradiol, dehydroepiandrosterone sulfate (DHEAS) and reactive oxygen species (ROS) were measured in cord blood of 821 newborns from a prospective study. After accounting for the effects of potential determinants of newborn LTL, a 10-fold increase in DHEAS concentration was associated with a 0.021 increase in T/S ratio of newborn LTL (95% confidence interval: 0.009-0.034, P = 0.0008). For newborns who fell in the lowest quartile of DHEAS level, the mean newborn LTL was estimated to be approximately 2.0% shorter than the newborns in the highest DHEAS concentration quartile (P = 0.0014). However, no association was found between newborn LTL and cortisol or estradiol. As expected, newborns with higher ROS level (ROS > 260 mol/L) had lower LTL compared to that with lower ROS level (ROS ≤ 260 mol/L) (P = 0.007). There was also an inverse relationship between DHEAS and ROS (P < 1×10^-4). Our findings suggest that exposure to DHEAS may exert a "programming" effect on the newborn telomere biology system.

Is cancer a severe delayed hypersensitivity reaction and histamine a blueprint?

Longevity and accumulation of multiple context-dependent signaling pathways of long-standing inflammation (antigen-load or oxidative stress) are the results of decreased/altered regulation of immunity and loss of control switch mechanisms that we defined as Yin and Yang of acute inflammation or immune surveillance. Chronic inflammation is initiated by immune disruptors-induced progressive changes in physiology and function of susceptible host tissues that lead to increased immune suppression and multistep disease processes including carcinogenesis. The interrelated multiple hypotheses that are presented for the first time in this article are extension of author's earlier series of 'accidental' discoveries on the role of inflammation in developmental stages of immune dysfunction toward tumorigenesis and angiogenesis. Detailed analyses of data on chronic diseases suggest that nearly all age-associated illnesses, generally categorized as 'mild' (e.g., increased allergies), 'moderate' (e.g., hypertension, colitis, gastritis, pancreatitis, emphysema) or 'severe' (e.g., accelerated neurodegenerative and autoimmune diseases or site-specific cancers and metastasis) are variations of hypersensitivity responses of tissues that are manifested as different diseases in immune-responsive or immune-privileged tissues. Continuous release/presence of low level histamine (subclinical) in circulation could contribute to sustained oxidative stress and induction of 'mild' or 'moderate' or 'severe' (immune tsunami) immune disorders in susceptible tissues. Site-specific cancers are proposed to be 'severe' (irreversible) forms of cumulative delayed hypersensitivity responses that would induce immunological chaos in favor of tissue growth in target tissues. Shared or special features of growth from fetus development into adulthood and aging processes and carcinogenesis are briefly compared with regard to energy requirements of highly complex function of Yin and Yang. Features of Yang (growth-promoting) arm of acute inflammation during fetus and cancer growth will be compared for consuming low energy from glycolysis (Warburg effect). Growth of fetus and cancer cells under hypoxic conditions and impaired mitochondrial energy requirements of tissues including metabolism of essential branched amino acids (e.g., val, leu, isoleu) will be compared for proposing a working model for future systematic research on cancer biology, prevention and therapy. Presentation of a working model provides insightful clues into bioenergetics that are required for fetus growth (absence of external threat and lack of high energy-demands of Yin events and parasite-like survival in host), normal growth in adulthood (balance in Yin and Yang processes) or disease processes and carcinogenesis (loss of balance in Yin-Yang). Future studies require focusing on dynamics and promotion of natural/inherent balance between Yin (tumoricidal) and Yang (tumorigenic) of effective immunity that develop after birth. Lawless growth of cancerous cells and loss of cell contact inhibition could partially be due to impaired mitochondria (mitophagy) that influence metabolism of branched chain amino acids for biosynthesis of structural proteins. The author invites interested scientists with diverse expertise to provide comments, confirm, dispute and question and/or expand and collaborate on many components of the proposed working model with the goal to better understand cancer biology for future designs of cost-effective research and clinical trials and prevention of cancer. Initial events during oxidative stress-induced damages to DNA/RNA repair mechanisms and inappropriate expression of inflammatory mediators are potentially correctable, preventable or druggable, if future studies were to focus on systematic understanding of early altered immune response dynamics toward multistep chronic diseases and carcinogenesis.

CAR T Cell Therapy: A Game Changer in Cancer Treatment

The development of novel targeted therapies with acceptable safety profiles is critical to successful cancer outcomes with better survival rates. Immunotherapy offers promising opportunities with the potential to induce sustained remissions in patients with refractory disease. Recent dramatic clinical responses in trials with gene modified T cells expressing chimeric antigen receptors (CARs) in B-cell malignancies have generated great enthusiasm. This therapy might pave the way for a potential paradigm shift in the way we treat refractory or relapsed cancers. CARs are genetically engineered receptors that combine the specific binding domains from a tumor targeting antibody with T cell signaling domains to allow specifically targeted antibody redirected T cell activation. Despite current successes in hematological cancers, we are only in the beginning of exploring the powerful potential of CAR redirected T cells in the control and elimination of resistant, metastatic, or recurrent nonhematological cancers. This review discusses the application of the CAR T cell therapy, its challenges, and strategies for successful clinical and commercial translation.

Lifelong leukocyte telomere dynamics and survival in a free-living mammal

Telomeres play a fundamental role in the maintenance of genomic integrity at a cellular level, and average leukocyte telomere length (LTL) has been proposed as a biomarker of organismal aging. However, studies tracking LTL across the entire life course of individuals are lacking. Here, we examined lifelong patterns of variation in LTL among four birth cohorts of female Soay sheep (Ovis aries) that were longitudinally monitored and sampled from birth to death. Over the first 4 months of life, there was within‐individual loss of LTL, consistent with findings in the human and primate literature, but there was little evidence of consistent LTL loss associated with age after this point. Overall, we observed only weak evidence of individual consistency in LTL across years and over the entire lifespan: Within‐individual variation was considerable, and birth cohorts differed markedly in their telomere dynamics. Despite the high levels of LTL variation within the lifetimes of individuals, there remained significant associations between LTL and longevity. Detailed analysis of the longitudinal data set showed that this association was driven by improved survival of individuals with longer LTL over the first 2 years of life. There was no evidence that LTL predicted survival in later adulthood. Our data provide the first evidence from a mammal that LTL can predict mortality and lifespan under natural conditions, and also highlight the potentially dynamic nature of LTL within the lifetimes of individuals experiencing a complex and highly variable environment.

Discarded Human Thymus Is a Novel Source of Stable and Long-Lived Therapeutic Regulatory T Cells

Regulatory T cell (Treg)-based therapy is a promising approach to treat many immune-mediated disorders such as autoimmune diseases, organ transplant rejection, and graft-versus-host disease (GVHD). Challenges to successful clinical implementation of adoptive Treg therapy include difficulties isolating homogeneous cell populations and developing expansion protocols that result in adequate numbers of cells that remain stable, even under inflammatory conditions. We investigated the potential of discarded human thymuses, routinely removed during pediatric cardiac surgery, to be used as a novel source of therapeutic Tregs. Here, we show that large numbers of FOXP3(+) Tregs can be isolated and expanded from a single thymus. Expanded thymic Tregs had stable FOXP3 expression and long telomeres, and suppressed proliferation and cytokine production of activated allogeneic T cells in vitro. Moreover, expanded thymic Tregs delayed development of xenogeneic GVHD in vivo more effectively than expanded Tregs isolated based on CD25 expression from peripheral blood. Importantly, in contrast to expanded blood Tregs, expanded thymic Tregs remained stable under inflammatory conditions. Our results demonstrate that discarded pediatric thymuses are an excellent source of therapeutic Tregs, having the potential to overcome limitations currently hindering the use of Tregs derived from peripheral or cord blood.

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

BACKGROUND

Telomeres provide a key mechanism for protecting the integrity of chromosomes and their attrition after cell division and during aging are evident in lymphocytes. However, the significance of telomere shortening in age-associated decline of immune function is unknown.

METHODS

We selected 22 HLA-A2-positive healthy older adults who have relatively short or long telomere lengths to compare their antibody response against the influenza vaccine, and their CD8(+) T-cell response against an influenza antigen.

RESULTS

B cells from individuals with a robust antibody response to the influenza vaccine had significantly longer telomeres than those with a poor antibody response. Monocyte-derived antigen-presenting cells of both short and long telomere groups induced similar expansions of influenza M1-specific CD8(+) T cells. Vaccination did not increase M1-specific CD8(+) T cells in blood, but M1-specific CD8(+) T cells from the long telomere group exhibited significantly greater expansion in vitro than those from the short telomere group. Finally, M1-specific CD8(+) T cells that underwent more expansions had significantly longer telomeres than cells with fewer divisions.

CONCLUSIONS

Telomere length is positively associated with a robust lymphocyte response, and telomere attrition may contribute to the age-associated decline of adaptive immunity.

Life equations for the senescence process

The Gompertz law of mortality quantitatively describes the mortality rate of humans and almost all multicellular animals. However, its underlying kinetic mechanism is unclear. The Gompertz law cannot explain the mortality plateau at advanced ages and cannot give an explicit relationship between temperature and mortality. In this study a reaction kinetics model with a time dependent rate coefficient is proposed to describe the survival and senescence processes. A temperature-dependent mortality function was derived. The new mortality function becomes the Gompertz mortality function with the same relationship of parameters prescribed by the Strehler–Mildvan correlation when age is smaller than a characteristic value δ, and reaches the mortality plateau when age is greater than δ. A closed-form analytical expression for describing the relationship of average lifespan with temperature and other equations are derived from the new mortality function. The derived equations can be used to estimate the limit of average lifespan, predict the maximal longevity, calculate the temperature coefficient of lifespan, and explain the tendency of the survival curve. This prediction is consistent with the most recently reported mortality trajectories for single-year birth cohorts. This study suggests that the senescence process results from the imbalance between damaging energy and protecting energy for the critical chemical substance in the body. The rate of senescence of the organism increases while the protecting energy decreases. The mortality plateau is reached when the protecting energy decreases to its minimal levels. The decreasing rate of the protecting energy is temperature-dependent. This study is exploring the connection between the biochemical mechanism and demography.

•

A temperature-dependent mortality function is derived.

•

The function reaches a mortality plateau as age>δ (a life characteristic value).

•

An expression for the temperature-dependent average lifespan is derived.

•

The equation for estimating the limit of average lifespan is derived.

From cellular senescence to Alzheimer's disease: The role of telomere shortening

The old age population is increasing worldwide as well as age related diseases, including neurodegenerative disorders, such as Alzheimer's disease (AD), which negatively impacts on the health care systems. Aging represents per se a risk factor for AD. Thus, the study and identification of pathways within the biology of aging represent an important end point for the development of novel and effective disease-modifying drugs to treat, delay, or prevent AD. Cellular senescence and telomere shortening represent suitable and promising targets. Several studies show that cellular senescence is tightly interconnected to aging and AD, while the role of telomere dynamic and stability in AD pathogenesis is still unclear. This review will focus on the linking mechanisms between cellular senescence, telomere shortening, and AD.

ATG-induced accelerated immune senescence: clinical implications in renal transplant recipients

Persistent ATG-induced CD4(+) T cell lymphopenia is associated with serious clinical complications. We tested the hypothesis that ATG induces accelerated immune senescence in renal transplant recipients (RTR). Immune senescence biomarkers were analyzed at transplant and one-year later in 97 incident RTR -62 patients receiving ATG and 35 receiving anti-CD25 mAb (α-CD25). This consisted in: (i) thymic output; (ii) bone marrow renewal of CD34(+) hematopoietic progenitor cells (CD34(+) HPC) and lymphoid (l-HPC) and myeloid (m-HPC) progenitor ratio; (iii) T cell phenotype; and (iv) measurement of T cell relative telomere length (RTL) and telomerase activity (RTA). Clinical correlates were analyzed with a 3 year follow-up. Thymic output significantly decreased one-year posttransplant in ATG-treated patients. ATG was associated with a significant decrease in l-HPC/m-HPC ratio. Late stage differentiated CD57(+) /CD28(-) T cells increased in ATG-treated patients. One-year posttransplant T cell RTL and RTA were consequently lower in ATG-treated patients. ATG is associated with accelerated immune senescence. Increased frequency of late differentiated CD4(+) T cell frequency at transplantation tended to be predictive of a higher risk of subsequent opportunistic infections and of acute rejection only in ATG-treated patients but this needs confirmation. Considering pretransplant immune profile may help to select those patients who may benefit from ATG to prevent severe infections and acute rejection.

Association of Average Telomere Length with Body-Mass Index and Vitamin D Status in Juvenile Population with Type 1 Diabetes

Background

Type 1 diabetes (T1D) is an autoimmune chronic disease where hyperglycemia, increased risk of oxidative stress, advanced glycation end-products and other genetic and environmental factors lead to T1D complications. Shorter telomeres are associated with hyperglycemic levels and lower serum vitamin D levels.

Methods

Average telomere length (ATL) in whole blood DNA samples was assessed with qPCR method in 53 Slovenian T1D children/adolescents (median age 8.7 years, 1:1.3 male/female ratio). Body mass index standard deviation score (BMI-SDS), glycated haemoglobin and serum level of vitamin D metabolite (25-(OH)-D3) and the age at the onset of T1D were collected from the available medical documentation.

Results

Results indicate shorter ATL in subjects with higher BMI-SDS when compared to those with longer ATL (0.455 ± 0.438, −0.63 ± 0.295; p=0.049). Subjects with higher BMI-SDS had lower serum vitamin D levels when compared to those with lower BMI-SDS (40.66 ± 3.07 vs. 52.86 ± 4.85 nmol/L; p=0.045). Vitamin D serum levels did not significantly differ between subjects with longer/shorter ATL.

Conclusion

T1D children/adolescents with shorter ATL tend to have higher BMI-SDS. Lower serum vitamin D levels were associated with higher BMI-SDS, while associations between vitamin D serum levels, age at the onset of T1D, glycated haemoglobin and ATL were not observed. Additional studies with more participants are required to clarify the role of the telomere dynamics in T1D aetiology and development of complications.

Short telomere length in peripheral blood leukocyte predicts poor prognosis and indicates an immunosuppressive phenotype in gastric cancer patients

Compelling evidences indicate that relative telomere length (RTL) in peripheral blood leukocytes (PBLs) can predict the clinical outcome of several cancers. However, to date, the prognostic value of leukocyte RTL in gastric cancer (GC) patients has not been explored. In this study, relative telomere length (RTL) in peripheral blood leukocytes (PBLs) was measured using a real-time PCR-based method in a total of 693 GC patients receiving surgical resection. The prognostic value of leukocyte RTL was first explored in the training set (112 patients) using Kaplan-Meier and Cox proportional hazards regression analyses. Then an independent cohort of 581 patients was used as a validation set. To explore potential mechanism, we detected the immunophenotypes of peripheral blood mononuclear cells and plasma concentrations of several cytokines in GC patients. Patients with short RTL showed significantly worse overall survival (OS) and relapse-free survival (RFS) than those with long RTL in all patient sets. Furthermore, leukocyte RTL and TNM stage exhibited a notable joint effect in prognosis prediction. Integration of TNM stage and leukocyte RTL significantly improved the prognosis prediction efficacy for GC. In addition, we found that patients with short RTL had a higher CD4(+) T cell percentage in PBMCs, CD19(+)IL-10(+) Breg percentage in B cells and plasma IL-10 concentration, indicating an enhanced immunosuppressive status with short leukocyte RTL. In conclusion, our study for the first time demonstrates that leukocyte RTL is an independent prognostic marker complementing TNM stage and associated with an immunosuppressive phenotype in the peripheral blood lymphocytes in GC patients.