Body mass index and leukocyte telomere length dynamics among older adults: Results from the ESTHER cohort

Telomere Length, Health, and Mortality in a Cohort of Older Black South African Adults

Telomere length (TL) may be a biomarker of aging processes as well as age-related diseases. However, most studies of TL and aging are conducted in high-income countries. Less is known in low- and middle-income countries (LMICs) such as South Africa, where life expectancy remains lower despite population aging. We conducted a descriptive analysis of TL in a cohort of older adults in rural South Africa. TL was assayed from venous blood draws using quantitative polymerase chain reaction (T/S ratio). We examined the correlation between TL and biomarkers, demographic characteristics, mental/cognitive health measures, and physical performance measures in a subsample of the Wave 1 2014-2015 "Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa" (HAALSI) cohort (n = 510). We used logistic regression to measure the association between TL and mortality through Wave 3 (2021-2022). In bivariate analyses, TL was significantly correlated with age (r = -0.29, p < .0001), self-reported female sex (r = 0.13, p = .002), mortality (r = -0.1297, p = .003), diastolic blood pressure (r = 0.09, p = .037), pulse pressure (r = -0.09, p = .045), and being a grandparent (r = -0.17, p = .0001). TL was significantly associated with age (β = -0.003; 95% confidence interval [CI] = -0.005, -0.003). TL was significantly associated in unadjusted multivariate analyses with mortality, but the relationship between TL and mortality was attenuated after adjusting for age (odds ratio [OR] = 0.19; 95% CI = 0.03, 1.27) and other covariates (OR = 0.17; 95% CI = 0.02, 1.19). Our study is the first analysis of TL in an older adult South African population. Our results corroborate existing relationships between TL and age, sex, cardiometabolic disease, and mortality found in higher-income countries.

Identifying effects of genetic obesity exposure on leukocyte telomere length using Mendelian randomization

Background

Observational studies have shown that obesity is closely associated with leukocyte telomere length (LTL). However, the causal relationship between obesity and LTL remains unclear. This study investigated the causal relationship between obesity and LTL through the Mendelian randomization approach.

Materials and Methods

The genome-wide association study (GWAS) summary data of several studies on obesity-related traits with a sample size of more than 600,000 individuals were extracted from the UK Biobank cohort. The summary-level data of LTL-related GWAS (45 6,717 individuals) was obtained from the IEU Open GWAS database. An inverse-variance-weighted (IVW) algorithm was utilized as the primary MR analysis method. Sensitivity analyses were conducted via MR-Egger regression, IVW regression, leave-one-out test, MR-pleiotropy residual sum, and outlier methods.

Results

High body mass index was correlated with a short LTL, and the odds ratio (OR) was 0.957 (95% confidence interval [CI] 0.942-0.973, p = 1.17E-07). The six body fat indexes (whole body fat mass, right leg fat mass, left leg fat mass, right arm fat mass, left arm fat mass, and trunk fat mass) were consistently inversely associated with LTL. Multiple statistical sensitive analysis approaches showed that the adverse effect of obesity on LTL was steady and dependable.

Conclusion

The current study provided robust evidence supporting the causal assumption that genetically caused obesity is negatively associated with LTL. The findings may facilitate the formulation of persistent strategies for maintaining LTL.

Longitudinal Association of Telomere Dynamics with Obesity and Metabolic Disorders in Young Children

In adults, short leukocyte telomere length (LTL) is associated with metabolic disorders, such as obesity and diabetes mellitus type 2. These associations could stem from early life interactions between LTL and metabolic disorders. To test this hypothesis, we explored the associations between LTL and metabolic parameters as well as their evolution over time in children with or without obesity at baseline. Seventy-three (n = 73) children attending our Outpatient Clinic for the Prevention and Management of Overweight and Obesity in Childhood and Adolescence, aged 2-10 years (mean ± SD: 7.6 ± 2.0 years), were followed for 2 to 4 years. Anthropometric, clinical, and biological (including LTL by Southern blot) measurements were performed annually. Baseline LTL correlated negatively with BMI (p = 0.02), fat percentage (p = 0.01), and blood glucose (p = 0.0007). These associations persisted after adjustments for age and sex. No associations were found between LTL attrition during the follow-up period and any of the metabolic parameters. In young children, obesity and metabolic disturbances were associated with shorter telomeres but were not associated with more pronounced LTL attrition. These results suggest that short telomeres contribute to the development of obesity and metabolic disorders very early in life, which can have a major impact on health.

Leukocyte telomere length and obesity in children and adolescents: A systematic review and meta-analysis

Background: Several studies have revealed the negative effects of adiposity on telomere length shortening. However, the results of the studies assessing the negative relationship between obesity and leukocyte telomere length (LTL) are not consistent. This systematic review and meta-analysis are aimed to pool the results of articles assessing the relationship between obesity and LTL among children and adolescents. Methods: To retrieve the related studies, four online databases including PubMed, Embase, ProQuest, and Scopus were searched until May 2022. Observational studies evaluating the relationship between obesity and LTL among apparently healthy children and adolescents (aged ≤18 years) were included in the study. We considered the studies that had reported a mean ± standard deviation of LTL. The random-effects model was used to assess the pooled weighted mean difference (WMD) and a 95% confidence interval (CI). Results: The search yielded seven studies from an initial 3,403 records identified. According to the results of seven articles with 4,546 participants, obesity was associated with LTL shortening among children and adolescents (WMD = -0.081; 95% CI: -0.137 to -0.026; p = 0.004; I2 = 99.9%). Also, no publication bias was observed. According to the results of subgrouping, significant results were only attributed to the studies conducted in Europe, with high quality scores, among overweight and obese adolescents, with a baseline LTL lower than 1, and performed in community-based school settings. Also, according to the subgrouping and meta-regression results, the obesity definition criteria and baseline LTL were the possible sources of between-study heterogeneity. Conclusion: We observed shorter LTL among overweight and obese children and adolescents. To obtain more reliable results, further longitudinal prospective studies with large sample sizes and more consistent and accurate definitions of obesity are required.

The association between visceral adiposity index and leukocyte telomere length in adults: results from National Health and Nutrition Examination Survey

BACKGROUND

Leukocyte telomere length (LTL) is a robust marker of biological aging, which is associated with obesity. Recently, the visceral adiposity index (VAI) has been proposed as an indicator of adipose distribution and function.

OBJECTIVE

To evaluated the association between VAI and LTL in adult Americans.

METHODS

There were 3193 participants in U.S. National Health and Nutrition Examination Surveys (1999-2002) included in this analysis. LTL was measured using quantitative PCR (qPCR) and expressed as telomere to single-gene copy ratio (T/S ratio). We performed multiple logistic regression models to explore the association between VAI and LTL by adjusting for potential confounders.

RESULTS

Among all participants, VAI was associated with the shorter LTL (β:  - 14.81, 95% CI  - 22.28 to  - 7.34, p < 0.001). There were significant differences of LTL in VAI tertiles (p < 0.001). Participants in the higher VAI tertile had the shorter LTL (1.26 ≤ VAI < 2.46: β =  - 130.16, 95% CI [ - 183.44,  - 76.87]; VAI ≥ 2.46: β =  - 216.12, 95% CI [ - 216.12,  - 81.42], p for trend: < 0.001) comparing with the lower VAI tertile. We also found a non-linear relationship between VAI and LTL. VAI was negatively correlated with LTL when VAI was less than 2.84.

CONCLUSIONS

The present study demonstrates that VAI is independently associated with telomere length. A higher VAI is associated with shorter LTL. The results suggest that VAI may provide prediction for LTL and account for accelerating the biological aging.

A causal relationship between leukocyte telomere length and multiple sclerosis: A Mendelian randomization study

Objectives

Multiple sclerosis (MS) is a chronic inflammatory autoimmune and degenerative disorder of the central nervous system. Telomeres are protective structures located at the ends of linear chromosomes, and leukocyte telomere length (LTL) is closely connected with cell aging and senescence. However, the relationship between LTL and the risk of MS remains unknown.

Methods

We performed a two-sample Mendelian randomization (MR) to evaluate whether LTL was causally associated with MS risk.

Results

In our MR analysis, 12 LTL-related variants were selected as valid instrumental variables, and a causal relationship between LTL and MS was suggested. The risk of MS nearly doubled as the genetically predicted LTL shortened by one standard deviation (SD) under the inverse variance weighted (IVW) fixed effect model (odds ratio (OR) = 2.00, 95% confidence interval (CI): 1.52-2.62, p = 6.01e-07). Similar estimated causal effects were also observed under different MR models. The MR–Egger regression test did not reveal any evidence of directional pleiotropy (intercept = -0.005, stand error (SE) = 0.03, p = 0.87). The Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) analysis also indicated no directional pleiotropy or outliers for any LTL-related IVs (p-global test = 0.13). In addition, a leave-one-out sensitivity analysis showed similar findings, which further emphasized the validity and stability of the causal relationship.

Conclusions

Our results suggest a potential causal effect of LTL on the risk of MS. Genetically predicted shorter LTL could increase the risk of MS in the European population. LTL should be noted and emphasized in the pathogenesis and treatment of MS.

Obesity Accelerates Leukocyte Telomere Length Shortening in Apparently Healthy Adults: A Meta-Analysis

Background

Shorter telomere length is associated with numerous comorbidities. Several studies have investigated the role of obesity in telomere shortening. In the current systematic review and meta-analysis, we summarized the results of studies that evaluated the association between obesity and telomere length.

Methods

A systematic search from Scopus, PubMed, Embase, and ProQuest electronic databases up to 19 March 2021 without language restriction was performed and after data extraction and screening, 19 manuscripts were eligible to be included in the final meta-synthesis.

Results

The highest category of telomere length was associated with an approximate 0.75 kg/m2 reduction in body mass index (BMI; WMD = -0.75 kg/m2; CI = -1.19, -0.31; p < 0.001; I 2 = 99.4%). Moreover, overweight/obese individuals had 0.036 kbp shorter telomere length compared with non-overweight/obese adults (WMD = -0.036; CI = -0.05, -0.02; p = 0.030; I 2 = 100%). According to the results of subgroupings, continent, age, and sample size could be possible sources of heterogeneity.

Conclusion

From the results, it was clear that obesity was associated with shorter telomere length. Because of the observational design of included studies, the causality inference of results should be done with caution; thus, further longitudinal studies are warranted for better inference of causal association.

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.

Telomere and Telomerase: Biological Markers of Organic Vital Force State and Homeopathic Treatment Effectiveness

BACKGROUND

 Philosophical-scientific correlations described in previous studies suggest that the genome can be the biological representation of the vital force, whilst the disease-promoting epigenetic alterations would be the biological representation of the chronic miasmas. In this study, we expand the functional correlation between vital force and chromosomes, describing the mechanism of action of the telomere-telomerase complex in the context of physiological balance.

AIMS

 The aim of the work is to study the role of the telomere-telomerase complex in cell vitality, biological aging, and the health-disease process, with the goal of proposing the use of telomere length as a biomarker of the vital force state and the effectiveness of homeopathic treatment.

RESULTS

 Similar to the vital force, telomere length and telomerase enzyme activity play an important role in maintaining cellular vitality, biological longevity, and physiological homeostasis. Telomere shortening functions as a biomarker of vital imbalance and is associated with numerous diseases and health disorders. On the other hand, health-promotion practices neutralize the pathological shortening of the telomeres, acting therapeutically in diseases or age-dependent health disorders.

CONCLUSIONS

 As a hypothetical biomarker of the vital force state, an intra-individual analysis of the mean leukocyte telomere length before, during, and after homeopathic treatment can be used as a biomarker of therapeutic effectiveness.

Telomere length: biological marker of cellular vitality, aging, and health-disease process

The aging process occurs due to the decline of vital physiological functions and adaptability of the body, being influenced by genetics and lifestyle. With advances in genetics, biological aging can be calculated by telomere length. Telomeres are regions at the ends of chromosomes that play a role in the maintenance and integrity of DNA. With biological aging, telomere shortening occurs, causing cellular senescence. Several studies show that shorter telomeres are associated with acute and chronic diseases, stress, addictions, and intoxications. Even in the current COVID-19 pandemic, telomere shortening is proposed as a marker of severity in individuals infected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). On the other hand, healthy lifestyle habits increase telomere length and balance of various cellular functions, preventing diseases.

Function of telomere in aging and age related diseases

Telomeres consist of specialized non-coding DNA repeat sequences. They are essential for preserving the integrity of the genome during cancer development, senescence. Mammalian telomeres might have 1-50 kb of telomeric DNA, which becomes 40-200 base pairs shorter after per cell cycle, and becomes 5-8 kilobase shorter during senescence. There are many studies on the correlation of telomere length and aging rate. However, as the differences in the methods used in the studies and the scarcity of prospective studies, factors affecting telomere length are not really well understood. Some of the age related diseases may develop due to telomere dysfunction and telomere shortness. The short telomere structure detected in both peripheral blood leukocytes and cells of the disease-related tissue has the feature of being a predictive marker for many age-related diseases. It is expected that with future research, telomere length analysis is expected to enter clinical practice.

Telomere length in depression and association with therapeutic response to electroconvulsive therapy and cognitive side-effects

BACKGROUND

Electroconvulsive therapy (ECT) is the most acutely effective treatment for severe treatment-resistant depression. However, there are concerns about its cognitive side-effects and we cannot yet confidently predict who will experience these. Telomeres are DNA-protein complexes that maintain genomic integrity. In somatic cells, telomeres shorten with each cell division. Telomere length (TL) can thus provide a measure of 'biological' aging. TL appears to be reduced in depression, though results are mixed. We sought to test the following hypotheses: (1) that TL would be shorter in patients with depression compared to controls; (2) that TL would be a predictor of response to ECT; and (3) that shorter TL would predict cognitive side-effects following ECT.

METHOD

We assessed TL in whole blood DNA collected from severely depressed patients (n = 100) recruited as part of the EFFECT-Dep Trial and healthy controls (n = 80) using quantitative real-time polymerase chain reaction. Mood and selected cognitive measures, including global cognition, re-orientation time, and autobiographical memory, were obtained pre-/post-ECT and from controls.

RESULTS

Our results indicate that TL does not differ between patients with depression compared to controls. TL itself was not associated with mood ratings and did not predict the therapeutic response to ECT. Furthermore, shorter baseline TL is not a predictor of cognitive side-effects post-ECT.

CONCLUSIONS

Overall, TL assessed by PCR does not represent a useful biomarker for predicting the therapeutic outcomes or risk for selected cognitive deficits following ECT.

Subcutaneous adipose tissue distribution and telomere length

Background Overweight and obese individuals have a reduced life expectancy due to cardiovascular disease (CVD), type 2 diabetes, stroke and cancer. Systemic inflammation and premature telomere shortening have been discussed as potential mechanisms linking these conditions. We investigated the relation of subcutaneous adipose tissue (SAT) distribution to leukocyte relative telomere length (RTL). Methods We measured RTL in 375 participants of the observational STYJOBS/EDECTA cohort (ClinicalTrials.gov Identifier NCT00482924) using a qPCR based method. SAT distribution was determined by lipometry yielding a percent body fat value and SAT thicknesses at 15 standardized locations across the entire body. A correlation analysis between RTL, age, sex, lipometry data and conventional body measures (body mass index [BMI], waist-, hip circumference, waist-to-hip ratio, waist-to-height ratio) was calculated. The strongest determinants of RTL were determined by a stepwise multiple regression analysis. Results RTL was not associated with age or sex. RTL was significantly negatively correlated with BMI, percent body fat, waist-, hip circumference and waist-to-height ratio. Furthermore, RTL correlated with SAT at the following locations: neck, triceps, biceps, upper back, front chest, lateral chest, upper abdomen, lower abdomen, lower back, hip, front thigh, lateral thigh, rear thigh and calf. Stepwise regression analysis revealed nuchal and hip SAT as the strongest predictors of RTL. No significant association was seen between RTL and waist-to-hip ratio. Conclusions RTL is negatively associated with parameters describing body fat composure. Nuchal and hip SAT thicknesses are the strongest predictors of RTL. Central obesity appears to correlate with premature genomic aging.

Telomere shortening associates with elevated insulin and nuchal fat accumulation

Obesity and relative leucocyte telomere length (RTL) are both linked to accelerated aging and premature mortality. We examined if nuchal subcutaneous adipose tissue (SAT) thickness, a surrogate marker of central trunk-weighted obesity, is an independent predictor of RTL that provides information beyond BMI, metabolic and inflammatory markers. RTL and nuchal SAT thickness were determined in 362 participants of the STYJOBS/EDECTA study (STYrian Juvenile Obesity Study, Early DEteCTion of atherosclerosis), which included overweight individuals and matched eutrophic controls. Fasting plasma samples were used for the measurement of leptin, resistin, adiponectin, glucose, insulin, high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), liver enzymes, creatinine, cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, oxidized LDL, triglycerides, homocysteine and uric acid. Furthermore, all participants underwent carotid artery ultrasound. Obese individuals had markedly higher body mass index (BMI), nuchal SAT thickness, hip and waist circumferences and carotid intima media thickness (IMT) than eutrophic controls. In addition, they showed typical biochemical abnormalities related to energy metabolism, systemic inflammation and liver function. RTL was inversely correlated with nuchal SAT thickness, IMT, hs-CRP, alkaline phosphatase, insulin, resistin, and leptin. Positive correlations were seen with homocysteine and creatinine. Stepwise linear regression analyses identified nuchal SAT thickness and insulin as the only significant predictors of RTL. In conclusion, nuchal SAT thickness is a robust predictor of RTL that provides information beyond traditional obesity-related metabolic and inflammatory biomarkers. This suggests an important role of fat depots at the neck for accelerated telomere shortening.

Reduction of Premature Aging Markers After Gastric Bypass Surgery in Morbidly Obese Patients

Background

Obesity is considered to be a major comorbidity. Obese patients suffer from an increased proinflammatory state associated with a premature aging phenotype including increased secretion of senescence-associated secretory proteins (SASP) and reduced telomere length. Micro-ribonucleic acids (miRNAs) are non-coding RNA molecules that could modify the post-transcriptional process. Several studies have reported associations between miRNAs and metabolic unhealthy conditions.

Aim

To determine if bariatric surgery and the resulting weight loss could reverse the premature aging phenotype.

Methods

We enrolled 58 morbidly obese patients undergoing bariatric surgery. Markers of premature aging including the SASP IL-6, CRP and PAI-1, 7 miRNAs, as well as telomere length and telomere oxidation in mononuclear cells were evaluated.

Results

Patients showed a significant drop of body mass index (BMI; 43.98 ± 3.5 versus 28.02 ± 4.1, p < 0.001). We observed a significant reduction in SASP including a reduction of 55% of plasma IL-6 levels (p = 0 < 0.001), 83% of CRP levels (p = 0.001) and 15% of plasma PAI-1 levels (p < 0.001). Telomere length doubled in the patient cohort (p < 0.001) and was accompanied by a reduction in the telomere oxidation index by 70% (p < 0.001). Telomere length was inversely correlated with telomere oxidation. The aging-associated miRNA miR10a_5p was upregulated significantly (p = 0.039), while the other tested miRNAs showed no difference.

Conclusion

Our data indicate a significant reduction of the proinflammatory SASP after bariatric surgery. We observed an increase in telomere length and reduced oxidative stress at telomeres. miR10a_5p which is downregulated during aging was upregulated after surgery. Overall, bariatric surgery ameliorated the premature aging phenotype.

Heart-Breaking Telomeres

Telomeres, the protective ends of linear chromosomes, shorten throughout an individual's lifetime. Accumulation of critically short telomeres is proposed to be a primary molecular cause of aging and age-associated diseases. Mutations in telomere maintenance genes are associated with pathologies referred to as or telomeropathies. The rate of telomere shortening throughout life is determined by endogenous (genetic) and external (nongenetic) factors. Therapeutic strategies based on telomerase activation are being developed to treat and prevent telomere-associated diseases, namely aging-related diseases and telomeropathies. Here, we review the molecular mechanisms underlying telomere driven diseases with particular emphasis on cardiovascular diseases.

Maternal pro-inflammatory state during pregnancy and newborn leukocyte telomere length: A prospective investigation

INTRODUCTION

Telomere biology plays a fundamental role in maintaining the integrity of the genome and cell, and shortened telomeres have been linked to several age-related diseases. The initial (newborn) telomere length (TL) represents a critically important feature of the telomere biology system. Exposure to a variety of adverse prenatal conditions such as maternal stress, suboptimal diet, obesity, and obstetric complications, is associated with shorter offspring TL at birth and in adult life. Many, if not all, of these exposures are believed to have an inflammatory component. In this context, stress-related immunological processes during pregnancy may constitute a potential additional biological pathway because they can affect telomere length and telomerase activity via transcriptions factors such as cyclic adenosine monophosphate-dependent transcription factor (ATF7) and nuclear factor-kappa B (NF-κB). Thus, in the present study we examined the hypothesis that maternal pro-inflammatory state across pregnancy, operationalized as the balance between tumor necrosis factor (TNF)-α, a major pro-inflammatory cytokine, and interleukin-10 (IL-10), the major anti-inflammatory cytokine, is associated with newborn leukocyte telomere length (LTL) at birth.

METHODS AND MATERIALS

Participants were healthy women (N = 112) recruited in early pregnancy. Concentrations of TNF- α and IL-10 were quantified in early, mid and late pregnancy from maternal blood samples. Telomere length was assessed in newborn blood samples soon after birth.

RESULTS

After adjusting for maternal age, maternal pre-pregnancy BMI, birth weight percentile, and infant sex, a higher mean TNF-α/IL-10 ratio across pregnancy was significantly associated with shorter newborn TL (β = -.205, p = .030). Newborn TL was, on average, 10% shorter in offspring of women in the upper compared to lower quartile of the TNF-α/IL-10 ratio during pregnancy.

DISCUSSION

These findings provide new evidence in humans for a potential "programming" mechanism linking maternal systemic pro-inflammatory processes during pregnancy with the initial (newborn) setting of her offspring's telomere system.

Telomeres, Telomerase and Ageing

Telomeres are specialised structures at the end of linear chromosomes. They consist of tandem repeats of the hexanucleotide sequence TTAGGG, as well as a protein complex called shelterin. Together, they form a protective loop structure against chromosome fusion and degradation. Shortening or damage to telomeres and opening of the loop induce an uncapped state that triggers a DNA damage response resulting in senescence or apoptosis.Average telomere length, usually measured in human blood lymphocytes, was thought to be a biomarker for ageing, survival and mortality. However, it becomes obvious that regulation of telomere length is very complex and involves multiple processes. For example, the "end replication problem" during DNA replication as well as oxidative stress are responsible for the shortening of telomeres. In contrast, telomerase activity can potentially counteract telomere shortening when it is able to access and interact with telomeres. However, while highly active during development and in cancer cells, the enzyme is down-regulated in most human somatic cells with a few exceptions such as human lymphocytes. In addition, telomeres can be transcribed, and the transcription products called TERRA are involved in telomere length regulation.Thus, telomere length and their integrity are regulated at many different levels, and we only start to understand this process under conditions of increased oxidative stress, inflammation and during diseases as well as the ageing process.This chapter aims to describe our current state of knowledge on telomeres and telomerase and their regulation in order to better understand their role for the ageing process.

The telomere world and aging: Analytical challenges and future perspectives

Telomeres, the terminal nucleoprotein structures of eukaryotic chromosomes, play pleiotropic functions in cellular and organismal aging. Telomere length (TL) varies throughout life due to the influence of genetic factors and to a complex balancing between "shortening" and "elongation" signals. Telomerase, the only enzyme that can elongate a telomeric DNA chain, and telomeric repeat-containing RNA (TERRA), a long non-coding RNA involved in looping maintenance, play key roles in TL during life. Despite recent advances in the knowledge of TL, TERRA and telomerase activity (TA) biology and their measurement techniques, the experimental and theoretical issues involved raise a number of problems that should carefully be considered by researchers approaching the "telomere world". The increasing use of such parameters - hailed as promising clinically relevant biomarkers - has failed to be paralleled by the development of automated and standardized measurement technology. Consequently, associating given TL values to specific pathological conditions involves on the one hand technological issues and on the other clinical-biological issues related to the planning of clinically relevant association studies. Addressing these issues would help avoid major biases in association studies involving TL and a number of outcomes, especially those focusing on psychological and bio-behavioral variables. The main challenge in telomere research is the development of accurate and reliable measurement methods to achieve simple and sensitive TL, TERRA, and TA detection. The discovery of the localization of telomeres and TERRA in cellular and extracellular compartments had added an additional layer of complexity to the measurement of these age-related biomarkers. Since combined analysis of TL, TERRA and TA may well provide more exhaustive clinical information than a single parameter, we feel it is important for researchers in the various fields to become familiar with their most common measurement techniques and to be aware of the respective merits and drawbacks of these approaches.

Incident hand OA is strongly associated with reduced peripheral blood leukocyte telomere length

OBJECTIVE

To evaluate the relationship of telomere length to the prevalence and incidence of hand osteoarthritis in a longitudinal cohort.

DESIGN

We conducted a cross-sectional and longitudinal analysis of data from a subset of participants in the Osteoarthritis Initiative (OAI) recruited between February 2004 and May 2006. 274 individuals were eligible for the study based on availability of both baseline and 48-month hand radiographs and peripheral blood leucocyte telomere length data. Mean telomere length of peripheral blood leukocytes (PBL)s from the DNA samples was determined using a validated quantitative polymerase chain reaction (PCR)-based assay, and hand radiographs were analyzed and graded using the Kellgren-Lawrence scale.

RESULTS

In joint -level analyses, prevalent Interphalangeal Joint Osteoarthritis (IPJOA) was significantly associated with PBL telomere length in the baseline sample in unadjusted analyses (RR = 2.84; 95% CI:0.87-9.29) or in models adjusted for age, sex, and body mass index (aRR = 1.10; 95% CI: 0.96-1.27). The association in crude and adjusted analyses appeared slightly stronger with incident IPJOA, especially in the subset with normal hands at baseline (aRR = 1.62; 95% CI: 1.02-2.57). PBL telomere length was also associated with prevalent HOA at baseline (significant in unadjusted analysis: RR = 1.22; 95% CI 1.06-1.42), but not after adjusting for covariates: aRR = 1.12; 95% CI: 0.96-1.30). The magnitude of association was stronger for incident HOA, especially incident symptomatic HOA (aRR = 1.53; 95% CI: 1.09-2.15).

CONCLUSIONS

In summary, the results of this exploratory analysis are confirmatory of previous work showing a cross-sectional relationship between telomere length and HOA and add to the field by demonstrating an even stronger association with incident IPJOA, both radiographic and symptomatic.

Possible association of the TERT promoter polymorphisms rs2735940, rs7712562 and rs2853669 with diabetes mellitus in obese elderly Polish population: results from the national PolSenior study

One of the markers of aging is lymphocyte telomere length (LTL), which is affected by genetic constitution of the organism and environmental conditions, such as development and diseases, including diabetes. The relationship of the later seems to be bilateral. The enzyme responsible for the maintenance of telomere length is a subunit of telomerase-telomerase reverse transcriptase (TERT). The aims of the present study were to (1) determine the influence of the TERT promoter sequence SNP variants on relative telomere length (RTL) in an elderly Polish population and (2) explore the potential associations of the SNPs with the type 2 diabetes mellitus (T2DM) in the obese individuals. Two highly homogenous subgroups of PolSenior participants were investigated, the first constituted 70 relatively healthy respondents and the second 70 individuals with T2DM. Telomere length ratio (T/S value) was measured; 1.5 kb part upstream of the transcription start site of the TERT promoter was sequenced, and the frequencies of polymorphisms were calculated and compared against analysed data. Low-frequency SNPs were evaluated but excluded from further comparative analyses to RTL and glucose metabolism markers. No significant difference in telomere length was found between the two studied subgroups. Univariate statistical analyses showed only a weak association of environmental or genetic factors altering this marker of aging. Approximate frequency of four SNPs in TERT promoter sequence was assessed in Polish population aged 65-95 years, but three of them (rs2735940, rs7712562 and rs2853669) were selected for further analyses. The SNP selection was based on their minor allele frequencies in general population and on published data. The univariate analysis has revealed that carriers of CC SNP (rs2853669) have had the shortest RTL in the T2DM group. Multivariate analysis has also revealed that the genetic effect of TERT promoter CC SNP was strengthened by the incidence of T2DM. The additional variation in RTL in paired groups indicates that in addition to T2DM and genetics, there are other factors contributing to development of the age-related diseases.

Adiposity, Telomere Length, and Telomere Attrition in Midlife: the 1946 British Birth Cohort

Background

Obesity has been linked with shorter telomere length, both of which have been implicated in ageing, but the impact of early life adiposity on telomere length is unclear.

Methods

We included 2,479 participants from the MRC National Survey of Health and Development with measurements of body mass index, waist and hip circumference, and leukocyte telomere length (LTL) at age 53, of whom 1,000 had second measurements at ages 60-64. Relative LTL was measured with rt-PCR. Linear regression was performed to investigate associations between adiposity and LTL. Body mass index from childhood through adulthood was used to assess adiposity across the life course.

Results

We found no cross-sectional associations between adiposity measures and LTL at ages 53 or 60-64. Longitudinally, each unit gain in waist circumference weakly corresponded with a 0.06% (95% CI: -1.31 to 0.10) LTL decrease annually, with association approaching statistical significance (p = 0.09). Being overweight at ages 6 and 15 corresponded to a nonsignificant shorter LTL at age 53 and they were associated with 2.06% (95% CI: 0.05-4.08%) and 4.26% (1.98-6.54%) less LTL attrition in midlife, respectively, compared to those who were not overweight.

Conclusion

There is a weak indication that greater telomere loss was seen with greater concurrent body mass index gain. Adolescent overweight corresponded to shorter telomeres in midlife, albeit weakly, and with less subsequent attrition. Our findings point toward potential pathways which may link adiposity and ageing outcomes.

Longitudinal associations of lifetime adiposity with leukocyte telomere length and mitochondrial DNA copy number

Adiposity may cause adverse health outcomes by increasing oxidative stress and systemic inflammation, which can be reflected by altered telomere length (TL) and mitochondrial DNA copy number (mtCN) in peripheral blood leukocytes. However, little is known about the influence of lifetime adiposity on TL and mtCN in later life. This study was performed to investigate the associations of lifetime adiposity with leukocyte TL and mtCN in 9613 participants from the Nurses' Health Study. A group-based trajectory modelling approach was used to create trajectories of body shape from age 5 through 60 years, and a genetic risk score (GRS) was created based on 97 known adiposity susceptibility variants. Associations of body shape trajectories and GRS with dichotomized TL and mtCN were assessed by logistic regression models. After adjustment for lifestyle and dietary factors, compared with the lean-stable group, the lean-marked increase group had higher odds of having below-median TL (OR = 1.18, 95% CI 1.04, 1.35; P = 0.01), and the medium-marked increase group had higher odds of having below-median mtCN (OR = 1.28, 95% CI 1.00, 1.64; P = 0.047). There was a suggestive trend toward lower mtCN across the GRS quartiles (P for trend = 0.07). In conclusion, telomere attrition may be accelerated by marked weight gain in middle life, whereas mtCN is likely to be reduced persistently by adiposity over the life course. The findings indicate the importance of lifetime weight management to preserve functional telomeres and mitochondria.

Investigating the associations between adiposity, life course overweight trajectories, and telomere length

Obesity may accelerate ageing through chronic inflammation. To further examine this association, we assessed current adiposity, adiposity at early adulthood and life course overweight trajectories in relation to leukocyte telomere length (LTL). We included a total of 7,008 nationally representative U.S. residents and collected information on objectively measured body mass index (BMI), waist circumference and percent body fat. BMI at age 25 and overweight trajectories were assessed using self-reported history. Leukocyte telomere length (LTL) relative to a standard DNA reference (T/S ratio) was quantified by polymerase chain reaction (PCR). Linear regression models were used to examine the difference in LTL across adiposity measures at examination, BMI at age 25, and overweight trajectories. A 0.2% decrease in telomere length (95% CI:−0.3 to −0.07%) was observed for every kg/m2 increase in BMI, whereas a unit increase in waist circumference (cm) and percent body fat contributed to a 0.09% and 0.01% decrease in LTL, respectively. Higher BMI and being obese at age 25 contributed to lower LTL at older ages. Associations between weight loss through life course and LTL were observed, which further marked the importance of life course adiposity dynamics as a determinant of ageing.

Steeper change in body mass across four decades predicts poorer cardiometabolic outcomes at midlife

OBJECTIVE

This study examined patterns of change in adiposity across four decades starting in young adulthood as well as associations between change and midlife cardiometabolic outcomes.

METHODS

BMI was assessed at ages 20, 40, 56, and 62 years in 977 male veterans from the Vietnam Era Twin Study of Aging. Age 62 (range 56-66) cardiometabolic outcomes included hypertension, diabetes, dyslipidemia, inflammation, and ischemic heart disease. Analyses included latent growth modeling (LGM), latent class growth modeling (LCGM), and logistic regression models.

RESULTS

Linear BMI slope was associated with all outcomes. Accelerated (quadratic) BMI slope was significantly associated with greater risk for hypertension, diabetes, dyslipidemia, and inflammation; odds ratios ranged from 1.93 (diabetes) to 3.15 (dyslipidemia). Initial BMI did not predict later outcomes. Linear slope contributed significant unique variance for diabetes and dyslipidemia even controlling for age 62 BMI. LCGM revealed three trajectories. Men with the relatively stable, lower BMI trajectory had significantly better outcomes than those with trajectories with accelerated increases, especially those including obesity.

CONCLUSIONS

How individuals reach late-midlife BMI is important. Steepness of BMI change across 40 years from young adulthood to late midlife, in addition to late-midlife BMI itself, was robustly associated with greater risk for poor cardiometabolic outcomes.

Association of Leukocyte Telomere Length and Mitochondrial DNA Copy Number in Children from Salamanca, Mexico

AIM

The purpose of this study was to determine if there is a correlation between telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) in children.

METHODS

Leukocyte TL and mtDNAcn were measured by real-time PCR in 98 Mexican children 6-12 years of age from Salamanca, México.

RESULTS

A positive association was found between TL and mtDNAcn after a natural log transformation (Pearson correlation r = 0.72; p < 0.0001). No correlation between age and body mass index (BMI) biomarkers was found, and no differences according to sex were observed. After adjustment for these variables, a linear regression model showed an association between TL and mtDNAcn (β = 0.739, 95% confidence interval 0.594; 0.885, p < 0.0001).

CONCLUSIONS

A strong positive correlation between TL and mtDNAcn was found in the study population; age, sex, and BMI seemed to have no effect on this correlation.

Leukocyte telomere length in relation to the risk of Barrett's esophagus and esophageal adenocarcinoma

Chronic inflammation and oxidative damage caused by obesity, cigarette smoking, and chronic gastroesophageal reflux disease (GERD) are major risk factors associated with Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). EAC has been increasing the past few decades, and early discovery and treatment are crucial for survival. Telomere shortening due to cell division and oxidative damage may reflect the impact of chronic inflammation and could possibly be used as predictor for disease development. We examined the prevalence of shorter leukocyte telomere length (LTL) among individuals with GERD, BE, or EAC using a pooled analysis of studies from the Barrett's and Esophageal Adenocarcinoma Consortium (BEACON). Telomere length was measured in leukocyte DNA samples by Q-PCR. Participants included 1173 patients (386 with GERD, 384 with EAC, 403 with BE) and 736 population-based controls. The association of LTL (in tertiles) along the continuum of disease progression from GERD to BE to EAC was calculated using study-specific odds ratios (ORs) and 95% confidence intervals (CIs) from logistic regression models adjusted for potential confounders. Shorter LTL were less prevalent among GERD patients (OR 0.57; 95% CI: 0.35-0.93), compared to population-based controls. No statistically significant increased prevalence of short/long LTL among individuals with BE or EAC was observed. In contrast to some earlier reports, our findings add to the evidence that leukocyte telomere length is not a biomarker of risk related to the etiology of EAC. The findings do not suggest a relationship between LTL and BE or EAC.