Gender and telomere length: systematic review and meta-analysis

Telomere length is independently associated with subclinical atherosclerosis in subjects with type 2 diabetes: a cross-sectional study

AIMS

Individuals with type 2 diabetes show shorter leukocyte telomere length (LTL) compared to people without diabetes. Reduced LTL is associated with increased carotid intima-media thickness (IMT) in healthy subjects. The aim of the study is to assess whether LTL also correlates with IMT in patients with diabetes.

METHODS

In a cohort of 104 subjects with type 2 diabetes and atherogenic dyslipidemia, we assessed anthropometric, hemodynamic and metabolic parameters. Common carotid IMT was expressed as the maximum IMT. LTL was assessed by a specific real-time PCR reaction.

RESULTS

At univariate analysis, IMT values were positively correlated with age (p < 0.001), previous history of cardiovascular events (p < 0.005), fasting plasma glucose (p < 0.01), HbA1c (p < 0.05) and negatively correlated with LTL (p < 0.05). In a multivariate model, age (p < 0.001) and LTL (p < 0.05) were the only independent predictors of maximum IMT, with an adjusted R (2) of 0.22.

CONCLUSIONS

LTL is an independent predictor of subclinical atherosclerosis pointing to a role of LTL as an early marker of vascular burden and cardiovascular disease also in type 2 diabetes.

Short telomere length and its correlation with gene mutations in myelodysplastic syndrome

Background

Telomere erosion can lead to genomic instability and cancer progression. It has been suggested that the shortest telomere, not the average telomere length (TL), is critical for cell viability. Some studies have shown shorter TL in myelodysplastic syndrome (MDS) patients but the critically short telomeres, the variability of TL within individual patient has not been evaluated. Thus, we aimed to investigate the TL of MDS patients and assessed the association of TL with recurrent genetic mutations in MDS.

Methods

We measured the TL of bone marrow nucleated cells for diagnostic samples at a single-cell level by quantitative fluorescence in situ hybridization (Q-FISH) for 58 MDS patients and analyzed the minimum, median, average, standard deviation, average of the 0th to 10th percentile TL within a patient, and the proportion of cells with TL that is shorter than the lowest 10th percentile of the normal control (NC). The correlations of TL to clinical parameters, cytogenetic results, and genetic mutations were assessed.

Results

MDS patients showed eroded telomeres and narrow distribution compared to the NC (P < 0.001, P = 0.018, respectively). Patients with mutation showed significantly lesser cells with short TL, below the lowest 10th percentile of the NC (P = 0.017), but no differences in TL were found according to mutations/cytogenetic abnormalities except for CSF3R mutation. However, those patients with a high percentage (≥80 %) of cells with short TL showed poorer overall survival (P = 0.021), and this was an independent prognostic factor, along with TP53, U2AF1 mutation, and high BM blast count (P = 0.044, 0.001, 0.004, 0.012, respectively).

Conclusions

The shortest TL, which determines the fate of the cell, was significantly shorter, and higher burden of cells with short TL were found in MDS, which correlated with poor survival, suggesting the need to measure TL in single cells by Q-FISH.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0287-9) contains supplementary material, which is available to authorized users.

Telomere Length Among Older U.S. Adults: Differences by Race/Ethnicity, Gender, and Age

OBJECTIVE

We examine race/ethnic, gender, and age differences in telomere length (TL) within a diverse, nationally representative sample of older adults.

METHOD

Data come from 5,228 White, Black, and Hispanic respondents aged 54+ in the 2008 Health and Retirement Study. TL was assayed from saliva using quantitative polymerase chain reaction (qPCR) by comparing telomere sequence copy number with a single gene copy number (T/S ratio). Linear regression was used to examine TL by race/ethnicity, gender, and age adjusting for social, economic, and health characteristics.

RESULTS

Women had longer TL than men (p < .05). Blacks ( p < .05) and Hispanics ( p < .10) had longer TL than Whites. Black women and men had the longest TL relative to other groups ( p < .05), while White men had the shortest TL ( p < .05). Black women and Hispanic men showed greater differences in TL with age.

DISCUSSION

Findings indicate social patterns in TL by race/ethnicity, gender, and age among older adults do not reflect differences observed in most population health outcomes.

Shorter telomeres in adults with Type 1 diabetes correlate with diabetes duration, but only weakly with vascular function and risk factors

OBJECTIVE

To determine if white blood cell (WBC) telomeres are shorter in Type 1 diabetes (T1D) than in subjects without diabetes (non-DB), and shorter in T1D subjects with vs. without vascular complications; and to determine associations with vascular biomarkers.

RESEARCH DESIGN AND METHODS

WBC relative telomere length (RTL) was determined by quantitative PCR in a cross-sectional study of 140 non-DB and 199 T1D adults, including 128 subjects without vascular complications (T1DNoCx) and 71 subjects with vascular complications (T1DCx). Relationships of RTL with age, T1D duration, arterial elasticity, pulse pressure and vascular risk factors were determined.

RESULTS

RTL did not differ by gender within T1D and non-DB groups. Age-adjusted RTL was shorter in T1D vs. non-DB subjects (1.48±0.03 AU vs. 1.64±0.04 AU, p=0.002), but did not differ by T1D complication status (T1DNoCX 1.50±0.04 vs. T1DCX 1.46±0.05, p=0.50), nor correlate with arterial elasticity. Univariate analysis in T1D showed RTL correlated (inversely) with age r=-0.27, p=0.0001, T1D duration r=-0.16, p=0.03, and pulse pressure (r=-0.15, p=0.04), but not with HbA1c, BP, renal function (serum creatinine, ACR, eGFR), lipids, insulin sensitivity, inflammation (CRP, CAMs) or oxidative stress (OxLDL, OxLDL/LDL-C, MPO, PON-1). Multiple regression analysis showed independent determinants of RTL were age and T1D presence (r=0.29, p<0.0001).

CONCLUSIONS

In this cross-sectional study telomeres were shorter in T1D. RTL correlated inversely with T1D duration, but did not differ by complication status and weakly correlated with pulse pressure and vascular risk factors. Only age and T1D were independent determinants of RTL. Longitudinal studies are merited.

Telomere length in subjects with schizophrenia, their unaffected siblings and healthy controls: Evidence of accelerated aging

Schizophrenia (SZ) is associated with broad burden. The clinical manifestations of SZ are related to pathophysiological alterations similar to what is seen in normal aging. Our aim was to evaluate the differences in telomere length (TL), a biomarker of cellular aging, in subjects with SZ (n=36), unaffected siblings (SB, n=36) and healthy controls (HC, n=47). SZ had shorter TL compared to HC, but no difference was found in SB comparing to SZ. These findings indicate that a pathological accelerated aging profile could be present in the course of SZ and further studies are needed to confirm TL as potential endophenotype, especially in at risk populations.

The impact of hypertension on leukocyte telomere length: a systematic review and meta-analysis of human studies

Shortened leukocyte telomere length (LTL) is a novel biomarker for age and age-related diseases. Several epidemiological studies have examined the association between telomere length in surrogate tissues (for example, blood cells) and hypertension, and meanwhile the majority of studies reported an association some individual studies do not. We carried out a systematic review and meta-analysis to address the hypothesis that, in humans, telomere length is related with hypertension. Searches were conducted in Pubmed by September 2015 and reference lists of retrieved citations were hand searched. Eligible studies measured telomeres for both hypertensive and normotensive subjects. No restrictions were placed on sample size, publication type, age or gender. We calculated summary estimates using fixed and random effects meta-analysis. Publication bias and heterogeneity among studies were further tested. Meta-analyses from 3097 participants (1415 patients with hypertension and 1682 control subjects) showed a significant standardized mean difference between LTL in hypertensive patients and controls, either in the fixed (P<5 × 10^-6) or the random model (P<0.005). Heterogeneity among studies was substantial (Q-statistic P-value <0.001, I² 97.73%). Sensitivity analysis indicated that no single study changed the standardized mean difference qualitatively (0.022> random model P-value >0.002). Egger's test for asymmetry of effect sizes (intercept±s.e.=-7.278±3.574; P=0.072) did not show evidence for strong study publication bias. Leukocyte telomeres may be shorter in hypertensive than in normotensive individuals. Larger studies controlling for confounder effects are needed to confirm these findings and further explore sources of heterogeneity.

Telomere length elongation after weight loss intervention in obese adults

INTRODUCTION

Telomeres may be considered markers of biological aging, shorter telomere length is associated with some age-related diseases; in several studies short telomere length has also been associated to obesity in adults and adolescents. However the relationship between telomere complex functions and obesity is still not clear. Aim of the study was to assess telomere length (TL) in adults' obese subjects before and after weight loss obtained by placement of bioenteric intragastric balloon (BIB) for 6months.

METHODS

We enrolled 42 obese subjects before and after BIB placement as weight loss intervention. Blood samples were collected in order to obtain DNA from leukocyte to measure TL by quantitative PCR.

RESULTS

Data were analyzed only in 37 subjects with complete data; all presented important body weight loss (124.06±26.7 vs 105.40±23.14, p<0.001) and more interesting they presented a significant increase in TL (3.58±0.83 vs 5.61±3.29, p<0.001). Moreover we observed a significant positive correlation between TL elongation and weight loss (r=0.44, p=0.007) as well as an inverse correlation between TL at baseline and TL elongation (r=-0.35, p=0.03).The predictors of TL elongation were once again weight loss and short TL at baseline (respectively p=0.007 and p=0.003).

CONCLUSIONS

Our study shows that weight loss is associated to telomere lengthening in a positive correlation: the greater weight loss the greater telomere lengthening; moreover telomere lengthening is more significant in those subjects with shortest telomeres at baseline.

Perceived stress and telomere length: A systematic review, meta-analysis, and methodologic considerations for advancing the field

IMPORTANCE

Psychological stress contributes to numerous diseases and may do so in part through damage to telomeres, protective non-coding segments on the ends of chromosomes.

OBJECTIVE

We conducted a systematic review and meta-analysis to determine the association between self-reported, perceived psychological stress (PS) and telomere length (TL).

DATA SOURCES

We searched 3 databases (PubMed, PsycInfo, and Scopus), completed manual searches of published and unpublished studies, and contacted all study authors to obtain potentially relevant data.

STUDY SELECTION

Two independent reviewers assessed studies for original research measuring (but not necessarily reporting the correlation between) PS and TL in human subjects. 23 studies met inclusion criteria; 22 (totaling 8948 subjects) could be meta-analyzed.

DATA EXTRACTION AND SYNTHESIS

We assessed study quality using modified MINORS criteria. Since not all included studies reported PS-TL correlations, we obtained them via direct calculation from author-provided data (7 studies), contact with authors (14 studies), or extraction from the published article (1 study).

MAIN OUTCOMES AND MEASURES

We conducted random-effects meta-analysis on our primary outcome, the age-adjusted PS-TL correlation. We investigated potential confounders and moderators (sex, life stress exposure, and PS measure validation) via post hoc subset analyses and meta-regression.

RESULTS

Increased PS was associated with a very small decrease in TL (n=8724 total; r=-0.06; 95% CI: -0.10, -0.008; p=0.01; α=0.025), adjusting for age. This relationship was similar between sexes and within studies using validated measures of PS, and marginally (nonsignificantly) stronger among samples recruited for stress exposure (r=-0.13; vs. general samples: b=-0.11; 95% CI: -0.27, 0.01; p=0.05; α=0.013). Publication bias may exist; correcting for its effects attenuated the relationship.

CONCLUSIONS AND RELEVANCE

Our analysis finds a very small, statistically significant relationship between increased PS (as measured over the past month) and decreased TL that may reflect publication bias, although fully parsing the effects of publication bias from other sample-size correlates is challenging, as discussed. The association may be stronger with known major stressors and is similar in magnitude to that noted between obesity and TL. All included studies used single measures of short-term stress; the literature suggests long-term chronic stress may have a larger cumulative effect. Future research should assess for potential confounders and use longitudinal, multidimensional models of stress.

Baseline biopsychosocial determinants of telomere length and 6-year attrition rate

BACKGROUND

Short leukocyte telomere length (TL) and accelerated telomere attrition have been associated with various deleterious health outcomes, although their determinants have not been explored collectively in a large-scale study.

MATERIAL AND METHODS

Leukocyte TL was measured (baseline N=2936; 6-year follow-up N=1860) in participants (18-65 years) from the NESDA study. Baseline determinants of TL included sociodemographics, lifestyle, chronic diseases, psychosocial stressors, and metabolic and physiological stress markers. Multivariate linear regression models were used to examine the associations between these determinants and (1) baseline TL, and (2) 6-year TL change. Multinomial logistic regression analyses were used to examine the predictors of telomere attrition and lengthening, as compared to stable TL.

RESULTS

Short baseline TL was associated with older age, male sex, non-European ethnicity, cigarette smoking, recent life events, and higher triglycerides, glucose and pre-ejection period (R(2)=11.3%). The 6-year telomere attrition was inversely associated with baseline TL (R(2)=51.6%); also older age, long sleep, not having a partner, high childhood trauma index, and gastrointestinal disease were associated with 6-year TL attrition (additional R(2)=3.7%). Telomere attrition seemed to have slightly more predictors than lengthening.

CONCLUSIONS

Sociodemographic, lifestyle, psychosocial stress and metabolic and physiological stress factors are cross-sectionally linked with TL. Telomere attrition over six years was strongly associated with baseline TL, suggesting an internal homeostatic influence. Modulation of the identified determinants may become target of future studies to promote telomere maintenance and healthy aging.

Marital disruption is associated with shorter salivary telomere length in a probability sample of older adults

RATIONALE

Marital disruption (i.e., marital separation, divorce) is associated with a wide range of poor mental and physical health outcomes, including increased risk for all-cause mortality. One biological intermediary that may help explain the association between marital disruption and poor health is accelerated cellular aging.

OBJECTIVE

This study examines the association between marital disruption and salivary telomere length in a United States probability sample of adults ≥50 years of age.

METHOD

Participants were 3526 individuals who participated in the 2008 wave of the Health and Retirement Study. Telomere length assays were performed using quantitative real-time polymerase chain reaction (qPCR) on DNA extracted from saliva samples. Health and lifestyle factors, traumatic and stressful life events, and neuroticism were assessed via self-report. Linear regression analyses were conducted to examine the associations between predictor variables and salivary telomere length.

RESULTS

Based on their marital status data in the 2006 wave, people who were separated or divorced had shorter salivary telomeres than people who were continuously married or had never been married, and the association between marital disruption and salivary telomere length was not moderated by gender or neuroticism. Furthermore, the association between marital disruption and salivary telomere length remained statistically significant after adjusting for demographic and socioeconomic variables, neuroticism, cigarette use, body mass, traumatic life events, and other stressful life events. Additionally, results revealed that currently married adults with a history of divorce evidenced shorter salivary telomeres than people who were continuously married or never married.

CONCLUSION

Accelerated cellular aging, as indexed by telomere shortening, may be one pathway through which marital disruption is associated with morbidity and mortality.

Maternal adiposity and infancy growth predict later telomere length: a longitudinal cohort study

BACKGROUND/OBJECTIVES

Maternal overweight and obesity during pregnancy, and childhood growth patterns are risk factors influencing long-term health outcomes among the offspring. Furthermore, poor health condition has been associated with shorter leukocyte telomere length in adult subjects. We aimed to assess whether maternal adiposity during pregnancy and growth trajectory during infancy predict leukocyte telomere length (LTL) in later life.

SUBJECTS/METHODS

We studied a cohort of 1082 subjects belonging to the Helsinki Birth Cohort Study, born between 1934 and 1944. They underwent two clinical visits 10 years apart (2001-2004 and 2011-2013), during which LTL and anthropometrics were assessed. Birth records included birth weight, length, maternal body mass index (BMI) at the end of pregnancy. Serial measurements of height and weight from birth to 11 years were available.

RESULTS

Higher maternal BMI was associated with shorter LTL in elderly women (r=-0.102, P=0.024) but not in men. Also, in women but not in men shorter LTL and greater telomere shortening over a 10-year interval were predicted by higher weight at 12 months of age (P=0.008 and P=0.029, respectively), and higher weight gain during the first 12 months of life (P=0.008 and P=0.006, respectively), particularly between 6 and 9 months of age (P=0.002 for both LTL and LTL shortening rate). A correlation between younger age at adiposity rebound and shorter LTL at 60 years (P=0.022) was also found.

CONCLUSIONS

High maternal adiposity during pregnancy is associated with shorter LTL in elderly female offspring, but not in men. Moreover, higher weight and weight gain during the first year of life and younger age at adiposity rebound predict shorter LTL in older age in women, suggesting that rapid growth during the perinatal period accelerates cellular aging in late adulthood.

Mediterranean diet and telomere length in high cardiovascular risk subjects from the PREDIMED-NAVARRA study

BACKGROUND & AIMS

A healthy lifestyle has been associated with longer telomeres, but whether Mediterranean Diet (MeDiet) affect telomere length (TL) has not been fully elucidated yet. Our aim was to assess the relationship between MeDiet and TL in high cardiovascular risk subjects in the context of a randomized nutritional intervention trial.

METHODS

We assessed 520 participants (55-80 years, 55% women) from the PREDIMED-NAVARRA trial. Leukocyte TL was measured by qPCR at baseline and after 5 years of a dietary intervention program where subjects were randomly assigned to a low-fat control diet or to two MeDiets, one supplemented with extra virgin olive oil (MeDiet-EVOO) and the other with mixed nuts (MeDiet-nuts). A validated 14-item questionnaire was used to appraise baseline adherence of participants to the MeDiet.

RESULTS

Better adherence to MeDiet (as appraised by the 14-item score) was associated with longer basal telomeres in women in the baseline cross-sectional analysis, whereas the opposite was observed in men (P interaction = 0.036). Female subjects who scored 10 points had longer basal telomeres (0.27, 95% CI: 0.03-0.52) than women scoring ≤6 points at the beginning of the study (-0.46, 95% CI: -0.85 to -0.7) (P = 0.003). However, allocation to the MeDiet-nuts group (-0.24, 95% CI: -0.38 to -0.01) was associated with a higher risk of telomere shortening after 5 years of intervention, whereas no differences were found for the MeDiet-EVOO group (0.14, 95% CI: 0.02-0.27), in comparison with the Control group (0.07, 95% CI: -0.08 to 0.23) (P = 0.003 and P = 0.537, respectively).

CONCLUSION

A greater baseline adherence to a Mediterranean dietary pattern was associated with longer telomeres only in women. No beneficial effect of the intervention with the MeDiet for the prevention of telomere shortening in comparison with a low-fat diet was observed.

Longitudinal telomere length shortening and cognitive and physical decline in later life: The Lothian Birth Cohorts 1936 and 1921

Telomere length is hypothesised to be a biological marker of both cognitive and physical ageing. Here we measure telomere length, and cognitive and physical abilities at mean ages 70, 73 and 76 years in the Lothian Birth Cohort 1936 (LBC1936), and at mean ages 79, 87, 90 and 92 years in the Lothian Birth Cohort 1921 (LBC1921). We investigate whether telomere length change predicts change in cognitive and physical abilities. In LBC1936 telomere length decreased by an average of 65 base pairs per year and in LBC1921 by 69 base pairs per year. However, change in telomere length did not predict change in cognitive or physical abilities. This study shows that, although cognitive ability, walking speed, lung function and grip strength all decline with age, they do so independently of telomere length shortening.

Body weight status and telomere length in U.S. middle-aged and older adults

OBJECTIVE

Telomere length has been proposed as a biomarker of biological aging. This study examined the relationship between body weight status and telomere length in U.S. middle-aged and older adults.

METHODS

Nationally representative data (N=2749) came from the Health and Retirement Study. Linear regressions were performed to examine the relationship between baseline body weight status reported in 1992 and telomere length measured in 2008 in the overall sample and by sex and racial/ethnic groups, adjusted for individual characteristics.

RESULTS

Baseline overweight (25kg/m²≤body mass index [BMI]<30kg/m²) and obesity (BMI≥30kg/m²) status positively predicted telomere length 17 years later. Compared with their normal weight counterparts, telomere length ratio was on average 0.062 (95% confidence interval=0.016, 0.109) and 0.125 (0.048, 0.202) larger among overweight and obese adults, respectively. In comparison to women and racial/ethnic minorities, the estimated positive associations between overweight and obesity status and telomere length were more salient among men and non-Hispanic whites, respectively.

CONCLUSIONS

The positive association between body weight status and telomere length found in this study was opposite to what existing biological model predicts, and could partially relate to the nonlinear relationship between body weight status and telomere length across age cohorts, and/or the lack of reliability of BMI as an indicator for adiposity in the older population. Large-scale longitudinal studies with baseline telomere length measures are warranted to replicate this study finding and explore the potential heterogeneous relationship between body weight status and telomere length.

Telomere length, genetic variants and risk of squamous cell carcinoma of the head and neck in Southeast Chinese

Telomere dysfunction participates in malignant transformation and tumorigenesis. Previous studies have explored the associations between telomere length (TL) and cancer susceptibility; however, the findings are inconclusive. The associations between genetic variants and TL have been verified by quite a few genome-wide association studies (GWAS). Yet, to date, there was no published study on the relationship between TL, related genetic variants and susceptibility to squamous cell carcinoma of the head and neck (SCCHN) in Chinese. Hence, we detected relative telomere length (RTL) by using quantitative PCR and genotyped seven selected single nucleotide polymorphisms by TaqMan allelic discrimination assay in 510 SCCHN cases and 913 controls in southeast Chinese. The results showed that RTL was significantly associated with SCCHN risk [(adjusted odds ratio (OR) = 1.19, 95% confidence interval (CI) = 1.08–1.32, P = 0.001]. Furthermore, among seven selected SNPs, only G allele of rs2736100 related to RTL in Caucasians was significantly associated with both the decreased RTL (P = 0.002) and the increased susceptibility to SCCHN in Chinese (additive model: adjusted OR = 1.17, 95%CI = 1.00–1.38, P = 0.049). These findings provide evidence that shortened TL is a risk factor for SCCHN, and genetic variants can contribute to both TL and the susceptibility to SCCHN in southeast Chinese population.

Depression and telomere length: A meta-analysis

BACKGROUND

Several recent studies have investigated the relationship between telomere length and depression with inconsistent results. This meta-analysis examined whether telomere length and depression are associated and explored factors that might affect this association.

METHODS

Studies measuring telomere length in subjects with clinically significant unipolar depression were included. A comprehensive search strategy identified studies in PubMed, MEDLINE, PsycINFO, Global Health, The Cochrane Library, and Web of Science. A structured data abstraction form was used and studies were appraised for inclusion or exclusion using a priori conditions. Analyses were conducted using standardized mean differences in a continuous random effects model.

RESULTS

Thirty-eight studies (N=34,347) met the inclusion criteria. The association between depression and telomere length was significant, with a Cohen's d effect size of -0.205 (p<0.0001, I(2)=42%). Depression severity significantly associated with telomere length (p=0.03). Trim and fill analysis indicated the presence of publication bias (p=0.003), but that the association remained highly significant after accounting for the bias. Subgroup analysis revealed depression assessment tools, telomere measurement techniques, source tissue and comorbid medical conditions significantly affected the relationship.

LIMITATIONS

Other potentially important sub-groups, including antidepressant use, have not been investigated in sufficient detail or number yet and thus were not addressed in this meta-analysis.

CONCLUSIONS

There is a negative association between depression and telomere length. Further studies are needed to clarify potential causality underlying this association and to elucidate the biology linking depression and this cellular marker of stress exposure and aging.

Ageing and the telomere connection: An intimate relationship with inflammation

Telomeres are the heterochromatic repeat regions at the ends of eukaryotic chromosomes, whose length is considered to be a determinant of biological ageing. Normal ageing itself is associated with telomere shortening. Here, critically short telomeres trigger senescence and eventually cell death. This shortening rate may be further increased by inflammation and oxidative stress and thus affect the ageing process. Apart from shortened or dysfunctional telomeres, cells undergoing senescence are also associated with hyperactivity of the transcription factor NF-κB and overexpression of inflammatory cytokines such as TNF-α, IL-6, and IFN-γ in circulating macrophages. Interestingly, telomerase, a reverse transcriptase that elongates telomeres, is involved in modulating NF-κB activity. Furthermore, inflammation and oxidative stress are implicated as pre-disease mechanisms for chronic diseases of ageing such as neurodegenerative diseases, cardiovascular disease, and cancer. To date, inflammation and telomere shortening have mostly been studied individually in terms of ageing and the associated disease phenotype. However, the interdependent nature of the two demands a more synergistic approach in understanding the ageing process itself and for developing new therapeutic approaches. In this review, we aim to summarize the intricate association between the various inflammatory molecules and telomeres that together contribute to the ageing process and related diseases.

Leukocyte telomere length is related to appendicular lean mass: cross-sectional data from the Berlin Aging Study II (BASE-II)

BACKGROUND

Age-related progressive loss of muscle mass is an increasing problem in our aging society, affecting physical ability, risk of falls, and need for health care. Telomere length has been recognized as a marker of biological age on the population level. The relation between muscle mass in advanced age and telomere length, however, has rarely been examined.

OBJECTIVE

We evaluated the relation between appendicular lean mass (ALM) and relative leukocyte telomere length (rLTL) in 1398 participants of the Berlin Aging Study II (mean ± SD age: 68.2 ± 3.7 y; 49.6% men).

DESIGN

rLTL was determined by real-time polymerase chain reaction. Lean mass was estimated by dual X-ray absorptiometry and examined as leg lean mass (LLM), ALM, and the ratio of ALM to body mass index (ALMBMI).

RESULTS

Weak, but highly significant (P < 0.001), correlations of rLTL with ALM (r = 0.248), ALMBMI (r = 0.254), and LLM (r = 0.263) were found. In the fully adjusted model that included age, BMI, low-grade inflammation, lifestyle factors, and morbidities as potential confounders, rLTL was associated with ALM (β = 1.11, SEM = 0.46, P = 0.017), LLM (β = 1.20, SEM = 0.36, P = 0.001), and ALMBMI (β = 0.04, SEM = 0.02, P = 0.013) in men and with LLM in women (β = 0.78, SEM = 0.35, P = 0.026).

CONCLUSIONS

Our results suggest that short telomeres may be a risk factor for lower ALM, particularly for low LLM. To confirm the association between telomere attrition and loss of LLM and ALMBMI, which are highly relevant for physical ability, further research in a longitudinal context is needed. The medical portion of this trial was registered in the German Clinical Trials Registry (http://drks-neu.uniklinik-freiburg.de/drks_web/navigate.do?navigationId=start) as DRKS00009277.

Telomere measurement in individuals occupationally exposed to pesticide mixtures in tobacco fields

Occupational exposure to pesticides in tobacco fields causes genetic damage in farmers. The aim of this study was to analyze tobacco farmers chronically exposed to low doses of pesticides and nicotine (present in the tobacco leaves) in relation to absolute telomere length (aTL), and explore the influence of lifestyle characteristics, oxidative stress, and inorganic element levels. DNA was isolated from peripheral blood samples from agricultural workers and non-exposed individuals, and aTL was measured by quantitative real time polymerase chain reaction (qPCR) analysis. Oxidative stress (thiobarbituric acid reactive substances [TBARS], which measures oxidative damage to lipids; and toxic equivalent antioxidant capacity [TEAC], which measures total equivalent antioxidant capacity) was evaluated in serum, and inorganic element content was analyzed in whole blood through particle-induced X-ray emission technique. It was found that exposure to pesticides and tobacco smoking had significant effects on aTL. Individuals occupationally exposed to complex mixtures of pesticides in tobacco fields and individuals who smoked had decreased aTL compared with the non-exposed group. TBARS and TEAC were significantly elevated in the exposed group. There were no significant differences in inorganic elements. There was no evidence of an influence of age, gender, consumption of alcoholic beverages, or intake of fruits and vegetables on aTL within the groups. In addition, years of work in the tobacco field in the exposed group did not influence any of the variables analyzed. Although further studies were needed, these results suggested differences in telomere maintenance in tobacco farmers compared with the control group, indicating that telomere length may be a good biomarker of occupational exposure.

hTERT genetic variation in depression

BACKGROUND

Telomeres are protective DNA-protein complexes forming the chromosome ends. TL differs between tissues. Shorter telomere length (TL) in blood leukocytes (LTL) has been associated with major depression, and with previous exposure to childhood adversity. TL studies on non-invasively sampled salivary DNA are less common. Telomerase, with its catalytic subunit hTERT, counteracts telomere shortening. Reduced telomerase activity associates with depression-like behavior in mice. Recently, the minor allele of the hTERT polymorphism rs2736100 was associated with shorter LTL among primarily healthy individuals. We hypothesized that (i) TL in saliva DNA is shortened in adults with a history of depression, and that (ii) rs2736100 is implicated in depression and depressive episodes in bipolar disorder type 1 (BD1).

METHODS

Individuals with a history of depression and those without (controls) were identified using self-reported questionnaires from a well-characterized population-based cohort. Clinical BD1 patients were diagnosed by specialized psychiatrists. Saliva TL was measured in age-matched depressed individuals and controls (n=662) using qRT-PCR. rs2736100 was genotyped in 436 depressed individuals, 1590 controls, and 368 BD1 patients.

RESULTS

Saliva TL was shorter in depressed individuals compared to controls. The rs2736100 minor allele was associated with depression among those without experience of childhood adversity, and with number of depressive episodes in BD1 patients responding well to lithium.

LIMITATION

Psychopathological symptoms were recorded at two time points only, 3 and 6 years prior to DNA sampling.

CONCLUSIONS

This is the first report on hTERT genetic variation in mood disorder. It proposes that genetic variation in hTERT may influence the susceptibility to depression.

Sports and Exercise at Different Ages and Leukocyte Telomere Length in Later Life--Data from the Berlin Aging Study II (BASE-II)

Physical activity and sports have repeatedly been reported to be associated with telomere length. We studied the association of different types of sports across different stages of life on relative leukocyte telomere length (rLTL) in advanced age.815 participants (397 men) from the Berlin Aging Study II aged over 61 years were included in the analysis. rLTL was measured by real time PCR and physical activity was determined retrospectively by questionnaire, assessing type and duration of sports in the past as well as currently. Five separate multiple linear regression models adjusted for various control variables were performed. 67.3% of participants exercised currently, whereas 19.4% performed sports only between the age of 20 and 30. rLTL was higher in subjects who stated to exercise currently (N = 456), and in subjects who engaged in endurance (N = 138) or intensive activity sports (N = 32). Current physical activity was positively associated with rLTL in the risk factor adjusted regression model (β = 0.26, p < 0.001) and practicing sports for a minimum of 10 years preceding the assessment had a significant effect on rLTL (β = 0.39, p = 0.011). The highest impact was seen for intensive activity sports (β = 0.79, p < 0.001) and physical activity since at least 42 years (β = 0.47, p = 0.001). However, physical activity only between 20 and 30 years of age did not affect rLTL in old age when compared to no sports at all (β = -0.16, p = 0.21). Physical activity is clearly associated with longer rLTL. The effect is seen with longer periods of physical activity (at least 10 years), with intensive sports activities having the greatest impact on rLTL. Our data suggest that regular physical activity for at least 10 years is necessary to achieve a sustained effect on rLTL.

Age-related arterial telomere uncapping and senescence is greater in women compared with men

Telomere uncapping increases with advancing age in human arteries and this telomere uncapping is associated with increased markers of senescence, independent of mean telomere length. However, whether there are sex specific differences in arterial telomere uncapping is unknown. We found that telomere uncapping (serine 139 phosphorylated histone γ-H2A.X in telomeres) in arteries was ~2.5 fold greater in post-menopausal women (n=17, 63±2 years) compared with pre-menopausal women (n=11, 30±2 years, p=0.02), while there was only a trend towards greater telomere uncapping in older men (n=26, 66±2 years) compared with young men (n=11, 31±2, p=0.11). Senescence markers, p53 bound to the p21 gene promoter and p21 gene expression, were 3-4 fold greater in post-menopausal compared with pre-menopausal women (p=0.01-0.02), but only 1.5-2 fold greater in older compared with young men (p=0.02-0.08). Blood glucose was related to telomere uncapping in women, while systolic blood pressure, pulse pressure and serum creatinine were related to telomere uncapping in men. Mean arterial telomere length decreased similarly in women and men with age (p<0.01). Thus, the age-related increase in arterial telomere uncapping and senescence is greater in women than men, despite similar age-related reductions in mean telomere length in both sexes.

Plasma vitamin D biomarkers and leukocyte telomere length in men

PURPOSE

Vitamin D may reduce telomere shortening through anti-inflammatory and anti-cell proliferation mechanisms. In women, higher plasma 25-hydroxyvitamin D (25(OH)D) has been shown to be associated with longer telomere length, but the relationship has not been assessed in men.

METHODS

We conducted a cross-sectional analysis of 25(OH)D, 1,25-dihydroxyvitamin D (1,25(OH)₂D) and relative leukocyte telomere length (LTL) among 2483 men [1832 men for 1,25(OH)₂D] who were selected as cases and controls in three studies of telomeres and cancer nested within the Health Professionals Follow-up Study. We also genotyped 95 SNPs representing common genetic variation in vitamin D pathway genes. LTL was measured by quantitative PCR, and z-scores within each study were calculated. Associations were assessed by linear as well as logistic regression adjusting for age and other potential confounders.

RESULTS

Age (P-trend < 0.0001), pack-years of smoking (P-trend = 0.04) and body mass index (P-trend = 0.05) were inversely associated with LTL. Neither 25(OH)D nor 1,25(OH)₂D was associated with LTL (multivariable-adjusted P-trend 0.69 and 0.41, respectively, for the linear regression model). One SNP in the retinoid X receptor alpha gene was associated with long LTL (P = 0.0003).

CONCLUSIONS

In this cross-sectional study of men, 25(OH)D and 1,25(OH)₂D were not associated with relative LTL.

Is bipolar disorder associated with accelerating aging? A meta-analysis of telomere length studies

BACKGROUND

Bipolar disorder (BD) is associated with a reduced life expectancy compared to the general population mainly due to a high prevalence of comorbid somatic illnesses. A model of accelerated aging has been proposed as a potential explanation to these epidemiological findings. Nevertheless, studies measuring telomere length (TL) in patients with BD compared to healthy controls have provided mixed results.

OBJECTIVE

To compare TL between BD patients and healthy controls, and to search for potential modeP<rators for observed differences.

METHODS

We performed a systematic review and meta-analysis of original studies comparing TL in patients with BD vs. healthy controls published up to February 24th, 2015 in main electronic databases. Heterogeneity was explored through meta-regression and subgroup analysis.

RESULTS

Seven studies met inclusion criteria (N=1115). There was no difference in TL between participants with BD and healthy controls (Hedges's g=-0.012; 95% CI=-0.418 to 0.393, P=0.952). There was no evidence for publication bias. Heterogeneity was high (I(2)=89.65%). In meta-regression analyses, the percentage of females in healthy control samples (P=0.04) and the methodological quality of included studies (P<0.001) emerged as significant moderators, while subgroup analyses suggest that the type of assay employed to measure TL and age- and gender-matching of BD and HC participants may contribute to heterogeneity.

CONCLUSIONS

Telomere length does not differ between participants with BD vs. healthy controls; this finding does not support the view of BD as an illness associated with accelerated cellular aging. However, more studies controlling for potential confounders are necessary.

Questioning causal involvement of telomeres in aging

Multiple studies have demonstrated that telomere length predicts mortality and that telomeres shorten with age. Although rarely acknowledged these associations do not dictate causality. I review telomerase knockout and overexpression studies and find little support that telomeres cause aging. In addition, the causality hypothesis assumes that there is a critical telomere length at which senescence is induced. This generates the prediction that variance in telomere length decreases with age. In contrast, using meta-analysis of human data, I find no such decline. Inferring the causal involvement of telomeres in aging from current knowledge is therefore speculative and could hinder scientific progress.

Telomere length is not associated with frailty in older Chinese elderly: Cross-sectional and longitudinal analysis

Telomere shortening has been associated with biological age and several chronic degenerative diseases. However, less is known about telomere length and frailty, which is an indicator of biological age. This study examines the association between telomere length and frailty in a prospective study over five years of 2006 men and women aged 65 years and older living in the community. The frailty status was determined by the Fried's criteria. Telomere length in leukocytes was measured using the quantitative polymerase chain reaction. Logistic regression was used to examine the association between telomere length and incidence of frailty. Among 2006 subjects (mean age 72.4±5.1 years, 51.3% women), the mean telomere length at baseline was 9.1±2.0kb and the frailty phenotype was detected in 127 subjects (6.3%). Male gender was related to shorter telomere length, with increased years of age related to a shortened telomere length (P<0.05). In both men and women, no statistically significant difference of telomere length and the frailty phenotype was observed at baseline. After 4 years of follow-up, 116 cases of frailty were identified. There was no association between telomere length and incident frailty. In conclusion, telomere length was not associated with frailty in this study population.

Telomere length and recurrence risk after curative resection in patients with early-stage non-small-cell lung cancer: a prospective cohort study

BACKGROUND

We hypothesized that telomere length in peripheral blood would have significant predictive value for risk of recurrence after curative resection in non-small-cell lung cancer (NSCLC).

METHODS

This prospective study included 473 patients with histologically confirmed early stage NSCLC who underwent curative therapy at MD Anderson Cancer Center between 1995 and 2008. Relative telomere length (RTL) of peripheral leukocytes was measured by real-time polymerase chain reaction. The risk of recurrence was estimated as hazard ratios (HRs) and 95% confidence intervals (CIs) using a multivariable Cox proportional hazard regression model.

RESULTS

Median duration of follow-up was 61 months, and 151 patients (32%) had developed recurrence at time of analysis. Patients who developed recurrence had significantly longer mean RTL compared with those without recurrence (1.13 versus 1.07, p = 0.046). A subgroup analysis indicates that women had longer RTL compared with men (1.12 versus 1.06, p = 0.025), and the patients with adenocarcinoma demonstrated longer RTL compared with those with other histologic types (1.11 versus 1.05, p = 0.042). To determine whether longer RTL in women and adenocarcinoma subgroup would predict risk of recurrence, multivariate Cox analysis adjusting for age, sex, stage, pack year and treatment regimens was performed. Longer telomeres were significantly associated with higher risk of developing recurrence in women (hazard ratio [HR], 2.25; 95% confidence interval [CI], 1.02-4.96, p = 0.044) and adenocarcinoma subgroups (HR, 2.19; 95% CI, 1.05-4.55, p = 0.036). The increased risk of recurrence due to long RTL was more apparent in women with adenocarcinoma (HR, 2.67; 95% CI, 1.19-6.03, p = 0.018).

CONCLUSIONS

This is the first prospective study to suggest that long RTL is associated with recurrence in early stage NSCLC after curative resection. Women and adenocarcinoma seem to be special subgroups in which telomere biology may play an important role.

Telomere Length Is Not Related to Established Cardiovascular Risk Factors but Does Correlate with Red and White Blood Cell Counts in a German Blood Donor Population

Telomere length (TL) is considered a marker of biological aging and has been associated with the presence of various coronary risk factors in patients. Much less is known about the relationships between TL and classic coronary risk factors in other populations. We measured TL in peripheral blood leukocytes of 343 middle-aged blood donors (mean age 40.2 ± 12.4 years; 201 men, 142 women) using quantitative polymerase chain reaction. Median TL was 0.86 (range: 0.48–1.85) relative TL units. In linear regression analyses with natural log-transformed T to S ratio as the dependent variable, there was a significant association with age (per year: beta = -0.007, p<0.001) and sex (males vs. females: beta = 0.075, p = 0.007) with longer telomeres in men. After adjusting for these two variables, we observed no association of TL with classic coronary risk factors including cholesterol (p = 0.36), triglyceride (p = 0.09), HDL-cholesterol (p = 0.26), LDL-cholesterol (p = 0.36), smoking (p = 0.97), and personal (p = 0.46) or family history (p = 0.63) of cardiovascular disease. However, we did find a significant positive association with white (p = 0.011) and red blood cell count (p = 0.031), hemoglobin (p = 0.014) and hematocrit (p = 0.013); we also found a borderline positive association with thrombocytes (p = 0.074). Positive associations remained significant for hemoglobin (p = 0.017), hematocrit (p = 0.023), and leukocytes (p = 0.009) in a subgroup with no reported vascular disease; associations were of borderline significance for erythrocytes (p = 0.053) and thrombocytes (p = 0.088) in this subgroup. The data do not support the concept that classic coronary risk factors contribute to telomere attrition in a blood donor population. However, telomere attrition may be a marker for reduced proliferation reserve in hematopoietic progenitor cells.

Leukocyte telomere length dynamics in women and men: menopause vs age effects

Background: A longer leukocyte telomere length (LTL) in women than men has been attributed to a slow rate of LTL attrition in women, perhaps due to high estrogen exposure during the premenopausal period.

Methods: To test this premise we performed a longitudinal study (an average follow-up of 12 years) in a subset of the population-based Danish National Twin Registry. Participants consisted of 405 women, aged 37.5 (range 18.0–64.3) years, and 329 men, aged 38.8 (range 18.0–58.5) years, at baseline examination.

Results: Women showed a longer LTL [kb ± standard error(SE)] than men (baseline: 7.01 ± 0.03 vs 6.87 ± 0.04; follow-up: 6.79 ± 0.03 vs 6.65 ± 0.03; both P = 0.005). Women displayed deceleration of LTL attrition (bp/years ± SE), as they transitioned from the premenopausal period (20.6 ± 1.0) through the perimenopausal period (16.5 ± 1.3) to the postmenopausal period (15.1 ± 1.7). Age was not associated with LTL attrition in women after statistical control for menopausal status. Men, in contrast, displayed a trend for age-dependent increase in the rate of LTL attrition, which differed significantly from the pattern in women (P for interaction = 0.01).

Conclusions: Results indicate that the premenopausal period is expressed in a higher rate of LTL attrition than the postmenopausal period. They further suggest that the sex gap in LTL stems from earlier ages—the period of growth and development. The higher rate of LTL attrition in premenopausal women, we propose, might relate to estrogen-mediated increased turnover of erythrocytes, menstrual bleeding or both.

Potential Risks in the Paradigm of Basic to Translational Research: A Critical Evaluation of qPCR Telomere Size Techniques

Real time qPCR has become the method of choice for rapid large-scale telomere length measurements. Large samples sizes are critical for clinical trials, and epidemiological studies. QPCR has become such routine procedure that it is often used with little critical analysis. With proper controls, the mean telomere size can be derived from the data and even the size can be estimated. But there is a need for more consistent and reliable controls that will provide closer to the actual mean size can be obtained with uniform consensus controls. Although originating at the level of basic telomere research, many researchers less familiar with telomeres often misunderstand the source and significance of the qPCR metric. These include researchers and clinicians who are interested in having a rapid tool to produce exciting results in disease prognostics and diagnostics than in the multiple characteristics of telomeres that form the basis of the measurement. But other characteristics of the non-bimodal and heterogeneous telomeres as well as the complexities of telomere dynamics are not easily related to qPCR mean telomere values. The qPCR metric does not reveal the heterogeneity and dynamics of telomeres. This is a critical issue since mutations in multiple genes including telomerase can cause telomere dysfunction and a loss of repeats. The smallest cellular telomere has been shown to arrest growth of the cell carrying the dysfunction telomere. A goal for the future is a simple method that takes into account the heterogeneity by measuring the highest and lowest values as part of the scheme to compare. In the absence of this technique, Southern blots need to be performed in a subset of qPCR samples for both mean telomere size and the upper and lower extremes of the distribution. Most importantly, there is a need for greater transparency in discussing the limitations of the qPCR data. Given the potentially exciting qPCR telomere size results emerging from clinical studies that relate qPCR mean telomere size estimates to disease states, the current ambiguities have become urgent issues to validate the findings and to set the right course for future clinical investigations.

Psychiatric disorders and leukocyte telomere length: Underlying mechanisms linking mental illness with cellular aging

Many psychiatric illnesses are associated with early mortality and with an increased risk of developing physical diseases that are more typically seen in the elderly. Moreover, certain psychiatric illnesses may be associated with accelerated cellular aging, evidenced by shortened leukocyte telomere length (LTL), which could underlie this association. Shortened LTL reflects a cell's mitotic history and cumulative exposure to inflammation and oxidation as well as the availability of telomerase, a telomere-lengthening enzyme. Critically short telomeres can cause cells to undergo senescence, apoptosis or genomic instability, and shorter LTL correlates with poorer health and predicts mortality. Emerging data suggest that LTL may be reduced in certain psychiatric illnesses, perhaps in proportion to exposure to the psychiatric illnesses, although conflicting data exist. Telomerase has been less well characterized in psychiatric illnesses, but a role in depression and in antidepressant and neurotrophic effects has been suggested by preclinical and clinical studies. In this article, studies on LTL and telomerase activity in psychiatric illnesses are critically reviewed, potential mediators are discussed, and future directions are suggested. A deeper understanding of cellular aging in psychiatric illnesses could lead to re-conceptualizing them as systemic illnesses with manifestations inside and outside the brain and could identify new treatment targets.

Childhood Conscientiousness and Leukocyte Telomere Length 40 Years Later in Adult Women--Preliminary Findings of a Prospective Association

Leukocyte telomere length (LTL) shortens with age, and is a prospective marker of mortality related to cardiovascular disease. Many health behaviors and social environmental factors have been found to be associated with LTL. Several of these are also associated with conscientiousness, a dispositional personality trait. Conscientiousness is a propensity to be planful, adhere to social norms, and inhibit pre-potent responses. Like LTL, conscientiousness is prospectively related to mortality, possibly through cumulative effects on health over the life course via multiple pathways. As a result, we hypothesized that childhood levels of conscientiousness would predict LTL prospectively in adulthood. We selected a sample of 60 women in the Hawaii Personality and Health Cohort; 30 described by their teachers as high on conscientiousness in childhood and 30 described as low on the trait. Dried blood spot samples collected in adulthood 40 years later were used as sources of DNA for the LTL assay. Conscientiousness was associated with longer LTL (p = .02). Controlling for age did not account for this association. Controlling for education and physiological dysregulation partially attenuated the association, and the effect remained significant when accounting for differences in LTL across cultural groups. These results represent the first evidence that childhood personality prospectively predicts LTL 40 years later in adulthood. Our findings would be consistent with a mediation hypothesis whereby conscientiousness predicts life paths and trajectories of health that are reflected in rates of LTL erosion across the lifespan.

Leukocyte telomere length and coronary artery calcium

Patients with histories of myocardial infarction display shortened leukocyte telomere length (LTL), but conflicting findings have been reported on the relation between LTL and subclinical coronary artery atherosclerosis, as expressed by coronary artery calcium (CAC). The aim of this study was to examine the relation between LTL, measured by Southern blots, and CAC in 3,169 participants in the National Heart, Lung, and Blood Institute Family Heart Study. Participants consisted of 2,556 whites, 613 blacks, 1,790 women, and 1,379 men. The odds of having CAC ≥100 for the shortest LTL tertile versus the longest LTL tertile were 1.95 (95% confidence interval [CI] 1.28 to 3.16) in white men and 1.76 (95% CI 1.18 to 2.45) in white women, after adjusting for multiple covariates of CAC. The corresponding odds ratios for blacks were 1.53 (95% CI 0.67 to 3.50) and 0.87 (95% CI 0.37 to 2.00). Significance levels of tests for trend across LTL tertiles were p = 0.002 in white men, p = 0.006 in white women, p = 0.32 in black men, and p = 0.74 in black women. The associations, or lack of associations, were independent of C-reactive protein levels and other risk factors for CAC. As previously shown in other studies, whites displayed shorter LTLs than blacks (p <0.0001). In conclusion, the higher the coronary artery atherosclerotic burden in whites, the shorter the LTL. This LTL-atherosclerosis connection is not found in blacks. The mechanisms for the racial difference in LTL, CAC, and their interrelations do not seem to be related to inflammation and merit further research.

Telomeres and essential hypertension

OBJECTIVES

This review aims to clarify the relationship between telomeres and essential hypertension.

DESIGN AND METHODS

A PubMed search and a critical review were performed relating to studies about the clinical and biological relevance of telomeres in essential hypertension.

RESULTS

Telomeres and telomerase activity play an important role in the occurrence and development of hypertension in both animal and human studies.

CONCLUSIONS

A more complete understanding of the molecular mechanisms underlying the development of hypertension could reduce the incidence of hypertension-related diseases.

Improving qPCR telomere length assays: Controlling for well position effects increases statistical power

OBJECTIVES

Telomere length (TL) is commonly measured using quantitative PCR (qPCR). Although, easier than the southern blot of terminal restriction fragments (TRF) TL measurement method, one drawback of qPCR is that it introduces greater measurement error and thus reduces the statistical power of analyses. To address a potential source of measurement error, we consider the effect of well position on qPCR TL measurements.

METHODS

qPCR TL data from 3,638 people run on a Bio-Rad iCycler iQ are reanalyzed here. To evaluate measurement validity, correspondence with TRF, age, and between mother and offspring are examined.

RESULTS

First, we present evidence for systematic variation in qPCR TL measurements in relation to thermocycler well position. Controlling for these well-position effects consistently improves measurement validity and yields estimated improvements in statistical power equivalent to increasing sample sizes by 16%. We additionally evaluated the linearity of the relationships between telomere and single copy gene control amplicons and between qPCR and TRF measures. We find that, unlike some previous reports, our data exhibit linear relationships. We introduce the standard error in percent, a superior method for quantifying measurement error as compared to the commonly used coefficient of variation. Using this measure, we find that excluding samples with high measurement error does not improve measurement validity in our study.

CONCLUSIONS

Future studies using block-based thermocyclers should consider well position effects. Since additional information can be gleaned from well position corrections, rerunning analyses of previous results with well position correction could serve as an independent test of the validity of these results.

Women and Lung Disease. Sex Differences and Global Health Disparities

There is growing evidence that a number of pulmonary diseases affect women differently and with a greater degree of severity than men. The causes for such sex disparity is the focus of this Blue Conference Perspective review, which explores basic cellular and molecular mechanisms, life stages, and clinical outcomes based on environmental, sociocultural, occupational, and infectious scenarios, as well as medical health beliefs. Owing to the breadth of issues related to women and lung disease, we present examples of both basic and clinical concepts that may be the cause for pulmonary disease disparity in women. These examples include those diseases that predominantly affect women, as well as the rising incidence among women for diseases traditionally occurring in men, such as chronic obstructive pulmonary disease. Sociocultural implications of pulmonary disease attributable to biomass burning and infectious diseases among women in low- to middle-income countries are reviewed, as are disparities in respiratory health among sexual minority women in high-income countries. The implications of the use of complementary and alternative medicine by women to influence respiratory disease are examined, and future directions for research on women and respiratory health are provided.

Shortened Telomeres in Families With a Propensity to Autism

OBJECTIVE

Shortened telomeres have been linked to poorer health outcomes. Exposure to psychological stress is associated with accelerated telomere shortening, and a well-established body of evidence indicates that families with a child with autism spectrum disorder (ASD) experience heightened levels of psychological stress. Also, alterations in a number of biological processes implicated in telomere length dynamics (i.e., oxidative stress, DNA methylation) have been linked to ASD susceptibility. We examined whether families of children with ASD who have an infant show shortened telomeres.

METHOD

Saliva samples were collected from infants, their older sibling (proband), and parents in families with or without a child with ASD. Infants and their families were designated as high-risk for ASD (HRA; n = 86) or low-risk for ASD (LRA; n = 118) according to the older siblings' diagnostic status. We used the real-time polymerase chain reaction (PCR) telomere assay to determine relative average telomere length for each participant.

RESULTS

HRA families demonstrated significantly shorter telomere length relative to LRA families. This effect was observed at the individual family member level, with infants, probands, and mothers in HRA families showing reduced relative telomere length compared to individuals in LRA families; although not significant, fathers of high-risk infants showed a similar pattern of decreased telomere length.

CONCLUSION

Families of children with ASD who have an infant show shortened telomeres relative to families with no history of ASD. These results suggest that such "high-risk" families should be monitored for the physical and mental health consequences that are often associated with accelerated telomere shortening.

Automated Assay of Telomere Length Measurement and Informatics for 100,000 Subjects in the Genetic Epidemiology Research on Adult Health and Aging (GERA) Cohort

The Kaiser Permanente Research Program on Genes, Environment, and Health (RPGEH) Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort includes DNA specimens extracted from saliva samples of 110,266 individuals. Because of its relationship to aging, telomere length measurement was considered an important biomarker to develop on these subjects. To assay relative telomere length (TL) on this large cohort over a short time period, we created a novel high throughput robotic system for TL analysis and informatics. Samples were run in triplicate, along with control samples, in a randomized design. As part of quality control, we determined the within-sample variability and employed thresholds for the elimination of outlying measurements. Of 106,902 samples assayed, 105,539 (98.7%) passed all quality control (QC) measures. As expected, TL in general showed a decline with age and a sex difference. While telomeres showed a negative correlation with age up to 75 years, in those older than 75 years, age positively correlated with longer telomeres, indicative of an association of longer telomeres with more years of survival in those older than 75. Furthermore, while females in general had longer telomeres than males, this difference was significant only for those older than age 50. An additional novel finding was that the variance of TL between individuals increased with age. This study establishes reliable assay and analysis methodologies for measurement of TL in large, population-based human studies. The GERA cohort represents the largest currently available such resource, linked to comprehensive electronic health and genotype data for analysis.

Where You Live May Make You Old: The Association between Perceived Poor Neighborhood Quality and Leukocyte Telomere Length

Background

Strong evidence supports that living in disadvantaged neighborhoods has direct unfavorable impact on mental and physical health. However, whether it also has direct impact on cellular health is largely unknown. Thus we examined whether neighborhood quality was associated with leukocyte telomere length, an indicator of cellular aging.

Methods

In May 2014, we extracted and analyzed baseline data from the Netherlands Study of Depression and Anxiety (NESDA), a large epidemiological study of individuals age between 18–65 years (n=2902). Telomere length was determined using quantitative polymerase chain reaction. Neighborhood quality was assessed using modified measures of perceived neighborhood disorder, fear of crime, and noise. We used multivariable linear regression models to examine association between perceived neighborhood quality and telomere length with comprehensive adjustment for individual and community characteristics related to socioeconomic and demographic status, urbanization level, mental and physical health, and lifestyle.

Results

Compared to individuals who reported good neighborhood quality, the mean telomere length of those who reported moderate neighborhood quality was approximately 69 base pair shorter (β =-69.33, 95% CI: -119.49, -19.17, p= 0.007), and that of those who reported poor neighborhood quality were 174 base pair shorter (β =-173.80, 95% CI: -298.80, -49.01, p=0.006). For illustrative purposes, one could extrapolate these outcomes to 8.7 and 11.9 years in chronological age, respectively.

Conclusion

We have established an association between perceived neighborhood quality and cellular aging over and above a range of individual attributes. Biological aging processes may be impacted by socioeconomic milieu.

Setting the trajectory: racial disparities in newborn telomere length

OBJECTIVE

To explore racial differences in newborn telomere length (TL) and the effect moderation of the sex of the infant while establishing the methodology for the use of newborn blood spots for TL analyses.

STUDY DESIGN

Pregnant mothers were recruited from the Greater New Orleans area. TL was determined via monochrome multiplex quantitative real-time polymerase chain reaction on DNA extracted from infant blood spots. Demographic data and other covariates were obtained via maternal report before the infant's birth. Birth outcome data were obtained from medical records and maternal report.

RESULTS

Black infants weighed significantly less than white infants at birth and had significantly longer TL than white infants (P=.0134), with the strongest effect observed in black female infants. No significant differences in gestational age were present.

CONCLUSIONS

Significant racial differences in TL were present at birth in this sample, even after we controlled for a range of birth outcomes and demographic factors. Because longer initial TL is predictive of more rapid TL attrition across the life course, these findings provide evidence that, even at birth, biological vulnerability to early life stress may differ by race and sex.

No strong correlations between serum cytokine levels, CMV serostatus and hand-grip strength in older subjects in the Berlin BASE-II cohort

Hand-grip strength is strongly correlated with measures of muscle mass and can be taken to predict morbidity and mortality. The aim of this study was to investigate the relationship between hand-grip strength and other markers associated with immune ageing, such as Cytomegalovirus (CMV) infection, leukocyte telomere length and serum levels of inflammatory and anti-inflammatory markers in the elderly. We have assessed grip strength with the Smedley Dynamometer in younger (22-37 years) and older (60-85 years) men and women in a sample of people living in Berlin (the BASE-II study). Serum cytokine levels were determined by flow-cytometry, CMV serostatus via ELISA and leukocyte telomere length by quantitative PCR. IL-1β levels tended to be negatively associated with grip strength, but we did not find a significant association with IL-6 levels. CMV-seropositivity was not associated with higher levels of IL-1β, IL-6 or TNF, nor with weaker grip strength in men or women at any age. A putative general measure of organismal ageing, overall leukocyte telomere length, was also found not to be associated with lower grip strength in the elderly. Hand-grip strength remains an important biomarker independent of CMV infection or shorter telomere lengths, and poorly reflected in peripheral pro-inflammatory cytokine levels, all of which have been associated in some studies with frailty and mortality.

Comparative Meta-Analysis of Transcriptomics Data during Cellular Senescence and In Vivo Tissue Ageing

Several studies have employed DNA microarrays to identify gene expression signatures that mark human ageing; yet the features underlying this complicated phenomenon remain elusive. We thus conducted a bioinformatics meta-analysis on transcriptomics data from human cell- and biopsy-based microarrays experiments studying cellular senescence or in vivo tissue ageing, respectively. We report that coregulated genes in the postmitotic muscle and nervous tissues are classified into pathways involved in cancer, focal adhesion, actin cytoskeleton, MAPK signalling, and metabolism regulation. Genes that are differentially regulated during cellular senescence refer to pathways involved in neurodegeneration, focal adhesion, actin cytoskeleton, proteasome, cell cycle, DNA replication, and oxidative phosphorylation. Finally, we revealed genes and pathways (referring to cancer, Huntington's disease, MAPK signalling, focal adhesion, actin cytoskeleton, oxidative phosphorylation, and metabolic signalling) that are coregulated during cellular senescence and in vivo tissue ageing. The molecular commonalities between cellular senescence and tissue ageing are also highlighted by the fact that pathways that were overrepresented exclusively in the biopsy- or cell-based datasets are modules either of the same reference pathway (e.g., metabolism) or of closely interrelated pathways (e.g., thyroid cancer and melanoma). Our reported meta-analysis has revealed novel age-related genes, setting thus the basis for more detailed future functional studies.

Absolute leukocyte telomere length in HIV-infected and uninfected individuals: evidence of accelerated cell senescence in HIV-associated chronic obstructive pulmonary disease

Combination antiretroviral therapy (cART) has extended the longevity of human immunodeficiency virus (HIV)-infected individuals. However, this has resulted in greater awareness of age-associated diseases such as chronic obstructive pulmonary disease (COPD). Accelerated cellular senescence may be responsible, but its magnitude as measured by leukocyte telomere length is unknown and its relationship to HIV-associated COPD has not yet been established. We measured absolute telomere length (aTL) in peripheral leukocytes from 231 HIV-infected adults. Comparisons were made to 691 HIV-uninfected individuals from a population-based sample. Subject quartiles of aTL were assessed for relationships with measures of HIV disease severity, airflow obstruction, and emphysema severity on computed tomographic (CT) imaging. Multivariable regression models identified factors associated with shortened aTL. Compared to HIV-uninfected subjects, the mean aTL in HIV-infected patients was markedly shorter by 27 kbp/genome (p<0.001); however, the slopes of aTL vs. age were not different (p=0.469). Patients with longer known durations of HIV infection (p=0.019) and lower nadir CD4 cell counts (p=0.023) had shorter aTL. Shorter aTL were also associated with older age (p=0.026), smoking (p=0.005), reduced forced expiratory volume in one second (p=0.030), and worse CT emphysema severity score (p=0.049). HIV-infected subjects demonstrate advanced cellular aging, yet in a cART-treated cohort, the relationship between aTL and age appears no different from that of HIV-uninfected subjects.

Leukocyte telomere length and left ventricular function after acute ST-elevation myocardial infarction: data from the glycometabolic intervention as adjunct to primary coronary intervention in ST elevation myocardial infarction (GIPS-III) trial

Background

Telomere length has been associated with coronary artery disease and heart failure. We studied whether leukocyte telomere length is associated with left ventricular ejection fraction (LVEF) after ST-elevation myocardial infarction (STEMI).

Methods and results

Leukocyte telomere length (LTL) was determined using the monochrome multiplex quantitative PCR method in 353 patients participating in the glycometabolic intervention as adjunct to primary percutaneous coronary intervention in STEMI III trial. LVEF was assessed by magnetic resonance imaging. The mean age of patients was 58.9 ± 11.6 years, 75 % were male. In age- and gender-adjusted models, LTL at baseline was significantly associated with age (beta ± standard error; −0.33 ± 0.01; P < 0.01), gender (0.15 ± 0.03; P < 0.01), TIMI flow pre-PCI (0.05 ± 0.03; P < 0.01), TIMI flow post-PCI (0.03 ± 0.04; P < 0.01), myocardial blush grade (−0.05 ± 0.07; P < 0.01), serum glucose levels (−0.11 ± 0.01; P = 0.03), and total leukocyte count (−0.11 ± 0.01; P = 0.04). At 4 months after STEMI, LVEF was well preserved (54.1 ± 8.4 %) and was not associated with baseline LTL (P = 0.95). Baseline LTL was associated with n-terminal pro-brain natriuretic peptide (NT-proBNP) at 4 months (−0.14 ± 0.01; P = 0.02), albeit not independent for age and gender.

Conclusion

Our study does not support a role for LTL as a causal factor related to left ventricular ejection fraction after STEMI.

Telomere shortening in Down syndrome patients--when does it start?

Down syndrome (DS) is one of the most common aneuploidy. In general population, its prevalence is 1:600-1:800 live births. It is caused by a trisomy of chromosome 21. DS is phenotypically manifested by premature aging, upward slant to the eyes, epicanthus, flattened face, and poor muscle tone. In addition to physical changes, this syndrome is characterized by early onset of diseases specific to old age, such as Alzheimer's disease, vision and hearing problems, and precocious menopause. Since DS symptoms include premature aging, the shortening of telomeres might be one of the markers of cellular aging. Consequently, the aim of the study was to determine the length of the telomeres in leukocytes from the blood of juvenile patients with DS (n=68) compared to an age-matched control group (n=56) and also to determine the diagnostic or predictive value for this parameter. We show that, for the first time, in juveniles, the average relative telomere length in studied subjects is significantly longer than in the control group (50.46 vs. 40.56, respectively arbitrary units [AU]; p=0.0026). The results provide interesting basis for further research to determine the causes and consequences of telomere maintaining and the dynamics of this process in patients with DS.

Telomerase dysregulation in the hippocampus of a rat model of depression: normalization by lithium

BACKGROUND

Telomeres are protective DNA-protein complexes at the ends of each chromosome, maintained primarily by the enzyme telomerase. Shortening of the blood leukocyte telomeres is associated with aging, several chronic diseases, and stress, eg, major depression. Hippocampus is pivotal in the regulation of cognition and mood and the main brain region of telomerase activity. Whether there is telomere dysfunction in the hippocampus of depressed subjects is unknown. Lithium, used in the treatment and relapse prevention of mood disorders, was found to protect against leukocyte telomere shortening in humans, but the mechanism has not been elucidated. To answer the questions whether telomeres are shortened and the telomerase activity changed in the hippocampus and whether lithium could reverse the process, we used a genetic model of depression, the Flinders Sensitive Line rat, and treated the animals with lithium.

METHODS

Telomere length, telomerase reverse transcriptase (Tert) expression, telomerase activity, and putative mediators of telomerase activity were investigated in the hippocampus of these animals.

RESULTS

The naïve Flinders Sensitive Line had shorter telomere length, downregulated Tert expression, reduced brain-derived neurotrophic factor levels, and reduced telomerase activity compared with the Flinders Resistant Line controls. Lithium treatment normalized the Tert expression and telomerase activity in the Flinders Sensitive Line and upregulated β-catenin.

CONCLUSION

This is the first report showing telomere dysregulation in hippocampus of a well-defined depression model and restorative effects of lithium treatment. If replicated in other models of mood disorder, the findings will contribute to understanding both the telomere function and the mechanism of lithium action in hippocampus of depressed patients.