Telomere length and risk of stroke in Chinese

Shorter Leukocyte Telomere Length Is Associated with Increased Major Adverse Cardiovascular Events or Mortality in Patients with Essential Hypertension

The association between leukocyte telomere length (LTL) alteration and major adverse cardiovascular events (MACE) or mortality in patients with hypertension is still unclear. 20,034 patients with essential hypertension were enrolled from UK biobank. Multivariable COX regression models were performed to assess the association. LTL was shorter in hypertensive patients with MACE compared to those without MACE. Hypertensive patients in the lowest LTL quartile were at higher risk to develop MACE (adjusted HR 1.15 [95% CI 1.02-1.29], vs top LTL quartile, p-trend = 0.03). Similarly, shorter LTL was related with increased mortality (adjusted HR 1.18[95% CI 1.06-1.3], lowest vs top LTL quartile, p-trend < 0.001). This investigation demonstrated that shorter LTL is associated with increased risk of MACE or mortality in patients with essential hypertension, which indicates that LTL may be a potential predictor of prognosis or underlying therapeutic target for hypertension.

Telomere length as a biomarker for cerebrovascular diseases: current evidence

Cerebrovascular disease (CVD) includes a range of conditions affecting the brain's blood vessels, which can result in reduced blood flow to brain tissue. The most common manifestation of CVD is stroke, the second leading cause of death and the third leading cause of disability worldwide. Major risk factors for CVD encompass gender, age, smoking, hypertension, diabetes, physical inactivity, obesity, alcohol consumption, and metabolic syndrome. Research suggests a link between telomere length and an increased risk of CVD, particularly in ischemic stroke cases. This review highlights key findings on the relationship between telomere length and CVD, underscoring its clinical importance. The analysis utilizes scientific literature from PubMed, Scopus, and SciELO up to 2024. Results show that shorter telomere length is associated with various types of CVD, including stroke, ischemic stroke, hemorrhagic stroke, and cardioembolic stroke. Some studies propose that telomere length measurement could be a valuable biomarker for CVD, potentially improving prevention, diagnosis, and management strategies.

Analysis of the Association between Telomere Length and Neurological Disability in Stroke Types

Background and Objectives: The association between neurological disability, prognosis, and telomere length (TL) in patients with stroke has been investigated in various ways. However, analysis of the type of stroke and ischemic stroke subgroups is limited. In this study, we aimed to determine the association between TL and neurological disability according to stroke type. Materials and Methods: This prospective study included patients with stroke who visited a single-center emergency department (ED) between January 2022 and December 2023. The association between TL and neurological disabilities, using the Modified Rankin Scale (mRS) and National Institutes of Health Stroke Scale (NIHSS), was evaluated according to the patient's stroke type and subgroup of ischemic stroke. Multivariate analysis was performed to determine the association between neurological disabilities in patients with ischemic stroke and the subgroups. Results: A total of 271 patients with stroke were enrolled. The NIHSS score was found to be higher at the time of ED visit (adjusted odds ratio [OR], 5.23; 95% confidence interval [CI], 1.59-17.2, p < 0.01) and 1 day later (adjusted OR, 7.78; 95% CI, 1.97-30.70, p < 0.01) in the ischemic stroke group with a short TL. In the other determined etiology (OD) or undetermined etiology (UD) group, the NIHSS was higher in the short TL group at the ED visit (adjusted OR, 7.89; 95% CI, 1.32-47.25, p = 0.02) and 1 day after (adjusted OR, 7.02; 95% CI, 1.14-43.47, p = 0.04). Conclusions: TL is associated with neurological disability in early ischemic stroke and is prominent in the UD and OD subgroups.

Association and causal impact of TERT genetic variants on peripheral blood leukocyte telomere length and cerebral small vessel disease risk in a Chinese Han population: a mendelian randomization analysis

BACKGROUND

Previous observational studies have highlighted potential relationships between the telomerase reverse transcriptase (TERT) gene, short leukocyte telomere length (LTL), and cerebrovascular disease. However, it remains to be established as to whether TERT gene variants are associated with an elevated risk of cerebral small vessel disease (CSVD), and whether there is a causal relationship between LTL and CSVD.

METHODS

Five TERT single nucleotide polymorphisms (SNPs) were analyzed in 307 CSVD patients and 320 healthy controls in whom LTL values were quantified. Allele models and four genetic models were used to explore the relationship between these SNP genotypes and CSVD risk. A Mendelian randomization analysis of CSVD risk was then performed using LTL-related SNPs and the polygenic risk score (PRS) constructed from these SNPs as genetic instrumental variables to predict the causal relationship between LTL and CSVD risk.

RESULTS

Model association analyses identified two SNPs that were significantly associated with CSVD risk. LTL was significantly correlated with age (P < 0.001), and the MR analysis revealed an association between short LTL and an elevated risk of CSVD. PRS-based genetic prediction of short LTLs was also significantly related to an elevated CSVD risk.

CONCLUSION

Multiple genetic models and MR results indicate that TERT gene SNPs may be related to an elevated risk of CSVD, and that shorter LTL may be causally linked to such CSVD risk.

Telomere length and stroke recurrence after ischemic stroke and TIA

BACKGROUND AND OBJECTIVE

Shortening telomere length (TL), as an indicator of aging, has been associated with increased risk of cardiovascular disease and incident stroke. However, there are limited data relating to the association between TL and recurrent stroke.

METHODS

Patients from the Third China National Stroke Registry who had whole genome sequencing (WGS) were selected. TL was estimated using TelSeq based on binary sequence alignment/map files derived from WGS data. Cox proportional hazards regression models were performed to assess the association of TL with recurrent stroke.

RESULTS

A total of 8041 patients with ischemic stroke (IS) or transient ischemic attack (TIA) were included. Mean TL was 2.14 ± 0.82 kb. Patients in the lowest tertile of TL had higher incidence of stroke recurrence compared to those in the middle and highest tertile (6.4% vs 5.9% vs 5.2%), but the difference was not longer significant after adjusting for age, sex, cardiovascular risk factors and stroke severity. Similarly, when analyzing TL as a continuous variable, the HR per 1000 bp increase in TL was significant 0.88 (0.79-0.98), but after adjusting for co-variates, was no longer significant (0.91; 95% confidence interval (CI), 0.81-1.02). In patients aged > 65 years, but not in younger patients, after adjusting for co-variates, TL was significantly associated with stroke recurrence. Compared to the lowest tertile, HRs (95% CI) after adjustment for all co-variates for the middle and highest tertiles were 0.78 (0.55-1.10) and 0.67 (0.46-0.98), respectively, with p for trend of 0.03. In analyses using TL as a continuous variable, adjusted HR (95% CI) per 1000 bp increase in TL was 0.80 (0.66-0.96). However, there was no significant interaction between TL and age on risk of stroke recurrence (p for interaction = 0.09).

CONCLUSIONS

In Chinese IS or TIA patients, no independent association was found between TL and risk of stroke recurrence after adjusting for co-variates. We found a possible association in older patients but this needs replicating.

Telomere Length as a marker of biological aging: A critical review of recent literature

INTRODUCTION

Aging is characterized as a syndrome of deleterious, progressive, universal, and irreversible function changes affecting every structural and functional aspect of the organism and accompanied by a generalized increase in mortality. Although a substantial number of candidates for biomarkers of aging have been proposed, none has been validated or universally accepted. Human telomeres constitute hexameric repetitive DNA sequence nucleoprotein complexes that cap chromosome ends, regulating gene expression and modulating stress-related pathways. Telomere length (TL) shortening is observed both in cellular senescence and advanced age, leading to the investigation of TL as a biomarker for aging and a risk factor indicator for the development and progression of the most common age-related diseases.

OBJECTIVE

The present review underlines the connection between TL and the pathophysiology of the diseases associated with telomere attrition.

METHODS

We performed a structured search of the PubMed database for peer-reviewed research of the literature regarding leukocyte TL and cardiovascular diseases (CVD), more specifically stroke and heart disease, and focused on the relevant articles published during the last 5 years. We also applied Hill's criteria of causation to strengthen this association.

RESULTS

We analyzed the recent literature regarding TL length, stroke, and CVD. Although approximately one-third of the available studies support the connection, the results of different studies seem to be rather conflicting as a result of different study designs, divergent methods of TL determination, small study samples, and patient population heterogeneity. After applying Hill's criteria, we can observe that the literature conforms to them weakly, with chronology being the only Hill criterion of causality that probably cannot be contested.

CONCLUSION

The present review attempted to examine the purported relation between leukocyte TL and age-related diseases such as CVD and more specific stroke and heart disease in view of the best established, comprehensive, medical and epidemiological criteria that have characterized the focused recent relevant research. Although several recommendations have been made that may contribute significantly to the field, a call for novel technical approaches and studies is mandatory to further elucidate the possible association.

Cardiometabolic profile and leukocyte telomere length in a Black South African population

Several studies have reported a possible association between leucocyte telomere length (LTL) and cardio-metabolic diseases (CMDs). However, studies investigating such association are lacking in South Africa despite having a very high prevalence of CMDs. We investigated the association between LTL and CMD risk profile in a black South African population. This was a cross-sectional study with participants > 21 years of age and residing in five townships in Cape Town. CMD markers were compared between men and women and across quartiles of LTL. Linear and logistic regressions relate increasing quartile and Log10LTL with CMD risk profile, with appropriate adjustment. Among 676-participants, diabetes, obesity and hypertension prevalence were 11.5%, 23.1% and 47.5%. Waist-circumference, hip-circumference and highly sensitive c-reactive protein values were significantly higher in women (all p < 0.001), while HDL-C (p = 0.023), creatinine (p = 0.005) and gamma glutamyl transferase (p < 0.001) values were higher in men. In age, sex and BMI adjusted linear regression model, Log10 of LTL was associated with low HDL-C (beta = 0.221; p = 0.041) while logistic regression showed a significant association between Log10LTL and prevalent dyslipidaemia characterised by high LDL-C. In this population, the relationship between LTL and CMD is weak given its association with only HDL-C and LDL-C.

Independent and joint effect of relative telomere length and type 2 diabetes on all-cause mortality in American adults

OBJECTIVE

The joint effect of leukocyte telomere length (LTL) and type 2 diabetes (T2D) on the risk of all-cause death has been sparsely explored. The study designed to examine the joint effect of T2D and LTL on the probability of death in American adults.

METHODS

A cohort of 6862 adults with LTL measurements and with or without T2D from the NHANES 1999-2002 with follow-up information until 2015 was studied. Quantitative PCR was used to measure the length of telomeres relative to standard reference DNA (T/S ratio). Individuals were grouped into three tertiles according to the LTL levels, with the first tertile demonstrating the lowest one and used as the reference group. The effects of LTL and T2D status on death were evaluated using Kaplan-Meier curves along with log-rank test. Three Cox proportional hazards models with adjustment for various confounders were used to examine the links between TL and all-cause death possibility using adjusted hazard ratios (HRs).

RESULTS

Adults in the sample averaged 45.54 years of age, with 49.51% being male. After a median follow-up period of 14.4 years, 1543 (22.5%) individuals died from all cause. The probability of all-cause mortality was higher among individuals with LTL in the highest tertile than individuals in the lowest tertile (aHR = 0.89; 95%CI: 0.77-1.03); however, the difference did not reach the level of statistical significance (P = 0.11). Conversely, the individuals with T2D had a higher probability of death than individuals without (aHR = 1.26; 95%CI: 1.06-1.50; P = 0.0092). When LTL and T2D status were investigated jointly, subjects in the highest TLT tertile and with T2D had the highest probability of mortality compared with their counterparts (aHR = 1.34; 95%CI: 1.07-1.68; P = 0.0101). However, there was no independent effect of low TLT on mortality as demonstrated among individuals with diabetes (aHR = 1.14; 95%CI: 0.95-1.38; P = 0.1662).

CONCLUSION

The joint effect of TLT and T2D was larger than the sum of the independent effects on the risk of all-cause death. Participants with high TLT and diabetes showed the highest possibility of death compared with other groups.

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.

Angptl2 is a Marker of Cellular Senescence: The Physiological and Pathophysiological Impact of Angptl2-Related Senescence

Cellular senescence is a cell fate primarily induced by DNA damage, characterized by irreversible growth arrest in an attempt to stop the damage. Senescence is a cellular response to a stressor and is observed with aging, but also during wound healing and in embryogenic developmental processes. Senescent cells are metabolically active and secrete a multitude of molecules gathered in the senescence-associated secretory phenotype (SASP). The SASP includes inflammatory cytokines, chemokines, growth factors and metalloproteinases, with autocrine and paracrine activities. Among hundreds of molecules, angiopoietin-like 2 (angptl2) is an interesting, although understudied, SASP member identified in various types of senescent cells. Angptl2 is a circulatory protein, and plasma angptl2 levels increase with age and with various chronic inflammatory diseases such as cancer, atherosclerosis, diabetes, heart failure and a multitude of age-related diseases. In this review, we will examine in which context angptl2 was identified as a SASP factor, describe the experimental evidence showing that angptl2 is a marker of senescence in vitro and in vivo, and discuss the impact of angptl2-related senescence in both physiological and pathological conditions. Future work is needed to demonstrate whether the senescence marker angptl2 is a potential clinical biomarker of age-related diseases.

Telomeres and Age-Related Diseases

Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.

Analogous telomeres shortening and different metabolic profile: hypertension versus hypertension/type 2 diabetes mellitus comorbidity

BACKGROUND

Eukaryotes chromosomal ends are capped and protected by telomeres, which are noncoding DNA repeats synthesized by telomerase enzyme. The telomerase enzyme is a nucleoprotein encoded by TERC and TERT genes. Naturally, the length of the telomeres shortens with each cell cycle but the shortening is fastened in certain age-related diseases like hypertension (HTN) and type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

Blood samples (n = 171) were obtained from Kuwaiti subjects with HTN, and HTN/T2DM comorbidity (HTN-DM) and healthy subjects. The leukocyte telomere length (LTL) was measured by SYBR green quantitative rtPCR, and plasma telomerase enzyme was measured by ELISA, in addition, three single nucleotide polymorphisms (SNPs) in telomere-related genes; TERC rs12696304GC, TERT rs2736100CA, and ACYP2 rs6713088GC were genotyped by real-time PCR.

RESULTS

Marked LTL shortening in subjects with HTN and HTN-DM compared to healthy subjects, P = 0.043 and P < 0.001, respectively, was noticed. On the contrary, the plasma telomerase enzyme levels and minor allele frequencies and genotypes of the tested SNPs were comparable between the study groups, except for TERT (CA) genotype which was over-represented in HTN (P = 0.037). Furthermore, the comparisons between HTN and HTN-DM revealed significantly higher total cholesterol (P = 0.015) and LDL-C (P = 0.008) in HTN, while higher insulin levels (P < 001), HOMA-IR (P < 001), and BMI (P = 0.004) were observed in HTN-DM.

CONCLUSION

This study showed comparable LTL shortening in HTN and HTN-DM, irrespective of plasma telomerase enzyme levels or tested TERC, TERT, and ACYP2 gene polymorphisms, although HTN and HTN-DM differed in several metabolic markers. More studies are required to affirm these observations.

The association between telomere length and ischemic stroke risk and phenotype

The chronological age of a person is a key determinant of etiology and prognosis in the setting of ischemic stroke. Telomere length, an indicator of biological aging, progressively shortens with every cell cycle. Herein, we determined telomere length from peripheral blood leukocytes by Southern blot analyses in a prospective cohort of ischemic stroke patients (n = 163) and equal number of non-stroke controls and evaluated its association with various ischemic stroke features including etiology, severity, and outcome. A shorter telomere length (i.e. lowest quartile; ≤ 5.5 kb) was significantly associated with ischemic stroke (OR 2.95, 95% CI 1.70–5.13). This significant relationship persisted for all stroke etiologies, except for other rare causes of stroke. No significant association was present between admission lesion volume and telomere length; however, patients with shorter telomeres had higher admission National Institutes of Health Stroke Scale scores when adjusted for chronological age, risk factors, etiology, and infarct volume (p = 0.046). On the other hand, chronological age, but not telomere length, was associated with unfavorable outcome (modified Rankin scale > 2) and mortality at 90 days follow-up. The association between shorter telomere length and more severe clinical phenotype at the time of admission, might reflect reduced resilience of cerebral tissue to ischemia as part of biological aging.

Association study of leukocyte telomere length and genetic polymorphism within hTERT promoter with type 2 diabetes in Bangladeshi population

Telomeres are protective cap on the ends of DNA of non-coding tandem repeats of TTAGGG. Human telomerase reverse transcriptase (hTERT) is a catalytic subunit of telomerase that maintains the structure of telomeres. Type 2 diabetes (T2D) affects multi-organ and telomere length by altering telomerase activity. We aimed to evaluate the relative telomere length (RTL) and risk association of rs2853669 with T2D in Bangladeshi population. RTL was measured in 408 unrelated Bangladeshi (224 T2D and 184 healthy) using primers for target gene and reference gene albumin. Genotypic frequencies for rs2853669 were determined using TaqMan® probes. The mean level of age adjusted RTL (AARTL) varied significantly between the healthy and individuals with T2D for all the genotypes with respect to rs2853669. Moreover, healthy individuals had significantly higher AARTL than T2D. Similar findings were observed when study participants were stratified based on their gender. Association studies revealed that under codominant model of inheritance, TC genotype showed protective role against development of type 2 diabetes. This study suggests a possible role of telomere biology in T2DM, but their association needs to be evaluated further with a larger series and matched healthy controls.

Down-regulated RGS5 by genetic variants impairs endothelial cell function and contributes to coronary artery disease

AIMS

Genetic contribution to coronary artery disease (CAD) remains largely unillustrated. Although transcriptomic profiles have identified dozens of genes that are differentially expressed in normal and atherosclerotic vessels, whether those genes are genetically associated with CAD remains to be determined. Here, we combined genetic association studies, transcriptome profiles and in vitro and in vivo functional experiments to identify novel susceptibility genes for CAD.

METHODS AND RESULTS

Through an integrative analysis of transcriptome profiles with genome-wide association studies for CAD, we obtained 18 candidate genes and selected one representative single nucleotide polymorphism (SNP) for each gene for multi-centred validations. We identified an intragenic SNP, rs1056515 in RGS5 gene (odds ratio = 1.17, 95% confidence interval =1.10-1.24, P = 3.72 × 10-8) associated with CAD at genome-wide significance. Rare genetic variants in linkage disequilibrium with rs1056515 were identified in CAD patients leading to a decreased expression of RGS5. The decreased expression was also observed in atherosclerotic vessels and endothelial cells treated by various cardiovascular risk factors. Through siRNA knockdown and adenoviral overexpression, we further showed that RGS5 regulated endothelial inflammation, vascular remodelling, as well as canonical NF-κB signalling activation. Moreover, CXCL12, a specific downstream target of the non-canonical NF-κB pathway, was strongly affected by RGS5. However, the p100 processing, a well-documented marker for non-canonical NF-κB pathway activation, was not altered, suggesting an existence of a novel mechanism by which RGS5 regulates CXCL12.

CONCLUSIONS

We identified RGS5 as a novel susceptibility gene for CAD and showed that the decreased expression of RGS5 impaired endothelial cell function and functionally contributed to atherosclerosis through a variety of molecular mechanisms. How RGS5 regulates the expression of CXCL12 needs further studies.

Association of greenspace exposure with telomere length in preschool children

Exposure to greenspace has been associated with a wide range of health benefits; however, the available evidence on the association of this exposure with telomere length (TL), an early marker of ageing, is still scarce. We investigated the association of greenspace exposure with TL in a sample of 200 preschool children (aged 5-7 years) residing in Sabzevar, Iran (2017). We comprehensively characterized different aspects of greenspace exposure encompassing residential, kindergarten, and total (including both residential and kindergarten) surrounding greenspace (using satellite-derived Normalized Difference Vegetation Index), residential and kindergarten distance to green spaces, time spent in private gardens and public green spaces, and the number of plant pots at home. Relative leukocyte TL (LTL) in blood samples of the study participants was measured using quantitative polymerase chain reaction (qPCR). We applied mixed effects linear regression models with kindergarten and qPCR plate as random effects, to estimate the association of indicators of greenspace exposure (one at a time) with LTL, controlled for relevant covariates. We observed an inverse association between distance from home and kindergarten to green spaces larger than 5000 m² and LTL. Moreover, higher total surrounding greenspace at 300m and 500m buffers and higher surrounding greenspace at 300m buffer around kindergarten and home were associated with longer LTL. Furthermore, longer time spent (h/week) in the public green spaces was associated with longer LTL. Our findings for residential and kindergarten distance to any green space (regardless of the size), residential surrounding greenspace at 100m and 500m buffers, kindergarten surrounding greenspace at 100m buffer, time spent in private gardens (h/week) and the number of plant pots at home were not conclusive. Our findings were generally suggestive for a positive association between greenspace exposure and LTL in preschool children. More studies are needed to confirm these findings in other settings with different climates and populations.

Association between telomere length in peripheral blood leukocytes and risk of ischemic stroke in a Han Chinese population: a linear and non-linear Mendelian randomization analysis

BACKGROUND

Many contradictory conclusions pertaining to the telomere length in peripheral leukocyte chromosomes as a potential biomarker for ischemic stroke (IS) risk have been reported by the various observational studies in previous years. This study aims to investigate whether the leukocyte telomere length is associated with an increased IS risk or not, based on the Mendelian randomization (MR) approach.

METHODS

Based on the NHGRI-EBI GWAS Catalog database, the Chinese online genetic database as well as the previous published studies, twelve single nucleotide polymorphisms (SNPs) with minor allele frequency ≥ 0.05 were selected and the leukocyte telomere length was measured in 431 first-ever IS patients and 304 healthy controls (quantitative polymerase chain reaction). To explore linear and non-linear effect of telomere length on the IS risk, we preformed the linear MR analysis (the inverse-variance weighted method, the maximum likelihood method, and the mode-based estimation method), and the non-linear MR analysis (semiparametric method with three tests for non-linearity, including the quadratic test, Cochran's Q test, and the fractional polynomial test).

RESULTS

Two verified SNPs (rs11125529 and rs412658) were chosen as instrumental variables. In linear MR analysis, the adjusted odds ratios and 95% confidence intervals of IS for genetically predicted telomere lengths, based on the two SNPs, were 1.312 (0.979 to 1.759), 1.326 (0.932 to 1.888) and 1.226 (0.844 to 1.781) for the inverse-variance weighted method, the maximum likelihood method, and the mode-based estimation method, respectively. Three tests for nonlinearity failed to reject the null exactly, indicating that the relationship between telomere length and IS risk is unlikely to be non-linear.

CONCLUSION

This MR study based on individual data does not provide strong evidence for a positive linear or non-linear effect of telomere length on the IS risk.

The association of mean telomere length with all-cause, cerebrovascular and cardiovascular mortality

Mean telomere length (MLT) is a marker of cell aging and may associate with age-related diseases. However, the relationship between MLT and mortality risk remains unclear. We aimed to investigate the relationship between MLT and all-cause, cerebrovascular and cardiovascular mortality among adults in United States. We analyzed data were from National Health and Nutrition Examination Survey (NHANES, 1999–2002) with follow-up data through 31 December 2015. Based on MLT, participants were categorized into low, middle and high groups. Multivariate Cox proportional hazards regression, subgroup analysis and generalized additive model (GAM) were performed by using hazard ratios (HRs) and 95% confidence intervals (CIs). A total of 7827 participants were included in analysis (48.18% male). After 158.26 months of follow-up on average, there were 1876 (23.97%), 87 (1.11%) and 243 (3.10%) onset of all-cause, cerebrovascular and cardiovascular mortality. After adjustment for potential confounders, using the low group as the reference, HRs for all-cause (0.87 and 0.86), cerebrovascular (0.75 and 0.75) and cardiovascular mortality (1.01 and 0.69) for the middle to high groups were not statistically significant (all P>0.05 for trend). MLT was non-linearly related to all-cause mortality but not to cerebrovascular and cardiovascular mortality. It was the first study to demonstrate the non-linear relationship between MLT and all-cause mortality.

Telomere Length: A Potential Biomarker for the Risk and Prognosis of Stroke

Stroke is one of the leading causes of death and disability worldwide. Age is associated with increased risk of stroke, while telomere length shortening plays a pivotal role in the process of aging. Moreover, telomere length shortening is associated with many risk factors of stroke in addition to age. Accumulated evidence shows that short leukocyte telomere length is not only associated with stroke occurrence but also associated with post-stroke recovery in the elderly population. In this review, we aimed to summarize the association between leukocyte telomere length and stroke, and discuss that telomere length might serve as a potential biomarker to predict the risk and prognosis of stroke.

No Causal Effect of Telomere Length on Ischemic Stroke and Its Subtypes: A Mendelian Randomization Study

Background: Epidemiological studies observing inconsistent associations of telomere length (TL) with ischemic stroke (IS) are susceptible to bias according to reverse causation and residual confounding. We aimed to assess the causal association between TL, IS, and the subtypes of IS, including large artery stroke (LAS), small vessel stroke (SVS), and cardioembolic stroke (CES) by performing a series of two-sample Mendelian randomization (MR) approaches. Methods: Seven single nucleotide polymorphisms (SNPs) were involved as candidate instrumental variables (IVs), summarized from a genome-wide meta-analysis including 37,684 participants of European descent. We analyzed the largest ever genome-wide association studies of stroke in Europe from the MEGASTROKE collaboration with 40,585 stroke cases and 406,111 controls. The weighted median (WM), the penalized weighted median (PWM), the inverse variance weighted (IVW), the penalized inverse variance weighted (PIVW), the robust inverse variance weighted (RIVW), and the Mendelian randomization-Egger (MR-Egger) methods were conducted for the MR analysis to estimate a causal effect and detect the directional pleiotropy. Results: No significant association between genetically determined TL with overall IS, LAS, or CES were found (all p > 0.05). SVS was associated with TL by the RIVW method (odds ratio (OR) = 0.72, 95% confidence interval (CI): 0.54–0.97, p = 0.028), after excluding rs9420907, rs10936599, and rs2736100. Conclusions: By a series of causal inference approaches using SNPs as IVs, no strong evidence to support the causal effect of shorter TL on IS and its subtypes were found.

The telomere length of peripheral blood cells is associated with the risk of ischemic stroke in Han population of northern China

BACKGROUND

Telomere length is closely related to the onset and prognosis of ischemic stroke. This study was to investigate the relationship between telomere length and the incidence of ischemic stroke in Han population of northern China.

METHODS

In the present study, 152 patients with ischemic stroke were selected as the case group, and 152 healthy persons were used as the control group. Detection of telomere length was done by real-time polymerase chain reaction after extraction of genomic DNA from peripheral venous blood.

RESULTS

Our results showed that the telomere length of the patients in the case group was significantly lower than that of the control group (Z = -11.843, P < .0001). Further analysis found that the telomere length of the control group was inversely correlated with age (r = -0.234, P = .004), and the telomere length and homocysteine (HCY) were inversely correlated in the case group (r = -0.176, P = .03), especially in women (r = -0.357, P = .024). Multivariate regression analysis showed that telomere length was a protective factor for ischemic stroke (odds ratio [OR] 95% confidence interval [95% CI] = 0.748 [0.681-0.823], β = -0.29, P < .0001). The receiver operating characteristic curve showed that telomere length was a good diagnostic biomarker of ischemic stroke (area under the curve: 0.894, sensitivity: 84.7%, specificity: 93.4%).

CONCLUSION

Our results indicate that shorter telomere length has some connection with the risk of ischemic stroke in the northern Chinese Han population. Telomere length might serve as a potential candidate biomarker for ischemic stroke. This requires a large sample to be further verified.

Relative Telomere Length and Stroke Risk in a Chinese Han Population

This study aimed to further understand the role of relative telomere length (RTL) in susceptibility to stroke and investigate the association regulator of telomere elongation helicase 1 (RETL1) gene polymorphisms and RTL. RTL was measured using the real-time quantitative polymerase chain reaction (qPCR) from 300 stroke patients and 299 healthy controls. Genotyping was performed using the Sequenom MassARRAY platform. The results indicated that stroke patients had significantly shorter median RTL than controls (P < 0.001). Compared with the longer RTL (≥ 0.766), the shorter RTL (< 0.766) was significantly increased the risk of stroke (odds ratio [OR] = 8.44, 95% confidence interval [CI] 5.42-13.14, P < 0.001). The RTL was categorized into tertiles, we found that the shorter RTL (0.515-1.366) (OR = 16.27, 95% CI 7.72-34.29, P < 0.001) and lowest RTL (< 0.515) (OR = 30.63, 95% CI 14.27-65.75, P < 0.001) were significantly increased stroke risk compared with the highest RTL (> 1.366). Stratified analysis showed that the shorter RTL was also significantly increased the risk of stroke compared with the longer RTL in male, age < 60 years and ≥ 60 years, except the female participants. In addition, individuals with the genotypes AA (rs2297441) and GG (rs6089953) have shorter telomeres than the genotypes GG (P = 0.031) and AA (P = 0.032), respectively. Our results suggested that shorter RTL was associated with an increased risk of stroke. The association was found between the genotypes AA (rs2297441) and GG (rs6089953) and shorter RTL in case group. Further studies in larger sample size and biological functional assays are warranted to validate our findings.

Relationship between short telomere length and stroke: A meta-analysis

BACKGROUND

Several epidemiological studies had been carried out in different population cohorts to estimate the relationship between the shortened telomere length and stroke. However, the results still remained dispute. Consequently, we conducted this meta-analysis to estimate the relationship between them.

METHODS

PubMed, EMBASE, and Web of Science were systematically searched for related articles to evaluate the association between "stroke" and "telomere length. STATA 12.0 software was used to perform the meta-analysis. The Cochran Q test and inconsistency index (I) were used to assess the heterogeneity. Begg funnel plot and Egger test were used to assess publication bias.

RESULTS

The meta-analysis was composed of 11 studies, consisting of 25,340 participants. We found a significant relationship between shortened telomere length and stroke (OR: 1.50, 95% CI: 1.13-2.0; P = .005); however, in the prospective and retrospective study subgroup, we did not find a statistical significant relationship between shortened telomere length and stroke (the prospective subgroup: OR: 1.41, 95% CI: 1-1.98; P = .051) (the retrospective subgroup: OR: 1.89, 95% CI: 0.96-3.72; P = .067).

Ageing at the level of telomeres in association to residential landscape and air pollution at home and work: a review of the current evidence

Studies suggest that leukocyte telomere length is an index of systemic ageing. Here, we discuss telomere length as a marker of biological ageing in relation to residential landscape (greenness), residential air pollution and work-related exposures. Telomere lengths are memories of cumulative oxidative and inflammatory stress, and show to have inverse associations with the risk of non-communicable diseases. For this reason, telomeres are considered as markers of biological ageing. Studies at birth, in children, young adulthood, and elderly show that residential green space, lower traffic exposure and long-term lower exposure to particulate air pollution are associated with longer telomeres. Work-related exposures including exposure to toxic metals, polycyclic aromatic hydrocarbons and particulate matter are associated with shorter telomeres for a given age. In contrast to chronic exposures, evidence is present of the observation that recent exposure is associated with longer telomeres. Our overview shows that the magnitude of residential and work-related environmental factors on telomere length are often as important as many classical lifestyle factors.

Telomere Length and Magnetic Resonance Imaging Findings of Vascular Brain Injury and Central Brain Atrophy: The Strong Heart Study

Telomeres are repeating regions of DNA that cap chromosomes. They shorten over the mammalian life span, especially in the presence of oxidative stress and inflammation. Telomeres may play a direct role in cell senescence, serving as markers of premature vascular aging. Leukocyte telomere length (LTL) may be associated with premature vascular brain injury and cerebral atrophy. However, reports have been inconsistent, especially among minority populations with a heavy burden of illness related to vascular aging. We examined associations between LTL and magnetic resonance imaging in 363 American Indians aged 64-93 years from the Strong Heart Study (1989-1991) and its ancillary study, Cerebrovascular Disease and Its Consequences in American Indians (2010-2013). Our results showed significant associations of LTL with ventricular enlargement and the presence of white matter hyperintensities. Secondary models indicated that renal function may mediate these associations, although small case numbers limited inference. Hypertension and diabetes showed little evidence of effect modification. Results were most extreme among participants who evinced the largest decline in LTL. Although this study was limited to cross-sectional comparisons, it represents (to our knowledge) the first consideration of associations between telomere length and brain aging in American Indians. Findings suggest a relationship between vascular aging by cell senescence and severity of brain disease.

Genome-Wide Association and Functional Studies Identify SCML4 and THSD7A as Novel Susceptibility Genes for Coronary Artery Disease

OBJECTIVE

The genetic contribution to coronary artery disease (CAD) remains largely unclear. We combined genetic screening with functional characterizations to identify novel loci and candidate genes for CAD.

APPROACH AND RESULTS

We performed genome-wide screening followed by multicenter validation in 8 cohorts consisting of 21 828 participants of Han ethnicity and identified 3 novel intragenic SNPs (single nucleotide polymorphisms), rs9486729 (SCML4 [Scm polycomb group protein-like 4]; odds ratio, 1.25; 95% CI, 1.17-1.34; P=3.51×10^-11), rs17165136 (THSD7A [thrombospondin type 1 domain-containing 7A]; odds ratio 1.28; 95% CI, 1.21-1.35; P<1.00×10^-25), and rs852787 (DAB1 [disabled-1]; odds ratio, 1.29; 95% CI, 1.21-1.38; P=2.02×10^-14), associated with CAD with genome-wide significance. The risk allele of rs9486729 and protective allele of rs17165136 were associated with the decreased expression of their host genes, SCML4 and THSD7A, respectively, whereas rs852787 did not have transcriptional effects on any gene. Knockdown of SCML4 activated endothelial cells by increasing the expression of IL-6, E-selectin, and ICAM and weakened their antiapoptotic activity, whereas the knockdown of THSD7A had little effect on these endothelial cell functions but attenuated monocyte adhesion via decreasing the expression of ICAM, L-selectin, and ITGB2. We further showed that inhibiting the expression of SCML4 exacerbated endothelial dysfunction and vascular remodeling in a rat model with partial carotid ligation.

CONCLUSIONS

We identify 3 novel loci associated with CAD and show that 2 genes, SCML4 and THSD7A, make functional contributions to atherosclerosis. How rs852787 and its host gene DAB1 are linked to CAD needs further studies.

The association of telomere attrition with first-onset stroke in Southern Chinese: a case-control study and meta-analysis

The relationship between telomere length and stroke was inconsistent mostly due to different pathogenesis of subtypes, environment and genetics. We aimed to assess whether leukocyte telomere contributes to stroke in Southern Chinese by investigating a case-control study comprising 543 cases (224 atherothrombotic stroke, 94 hemorrhagic stroke and 225 lacunar infraction) and 616 controls and replicated the investigation in an independent study comprising 773 cases and 875 controls with the same diagnostic criteria. Telomere was inversely correlated with increasing age in controls (correlation coefficient γ = −0.28, P < 0.001) and in cases with atherothrombotic stroke (γ = −0.17, P = 0.012). Individuals within the lowest tertile of telomere showed a higher risk for atherothrombotic stroke [odds ratio 2.33, 95% confidence (CI) 1.42–3.83; P = 0.003], whereas had a lower presence of lacunar infarction (OR 0.49, 95% CI 0.30–0.81; P = 0.007). Similar results were obtained in the second replication study. A further meta-analysis showed a 12% increased pooled risk of ischemic stroke (95% CI 1.04–1.18) in relation to shorter telomere, but this association was stronger in the retrospective studies and in Asians when stratified by study design and ethnicity. Our data provided the first evidence that in Southern Chinese stroke population, leukocyte telomere is independently associated with atherothrombotic stroke and lacunar infarction.

Telomere length associated with the risks of high-risk and ischemic stroke in southern Chinese Han population

Some previous studies suggested telomere length was associated with the risk of ischemic stroke (IS). The aim of this study was to further confirm the association between relative telomere length (RTL) and risk of IS and to especially explore its correlation with the risk of high-risk stroke population in southern Chinese Han. RTL was determined by using real-time quantitative polymerase chain reaction from 400 ischemic stroke patients, 409 high-risk stroke populations and 399 healthy controls. The correlations between the controls and the risk of high-risk and ischemic stroke were evaluated by using an unconditional logistic regression. IS patients have shown longer RTL than controls (median1.52vs1.11, p60 years) and gender suggested that the first and second tertile of RTL were correlated with the risk of IS in each group when the second tertile was used as a reference. However, the increased risk for high-risk stroke populations were only presented in the first tertile of RTL in the age≤60 years and female groups. the RTL was associated with an increased risk of ischemic stroke, while it elevated the risk of high-risk stroke in some specific subpopulations.

Interactions between ACYP2 genetic polymorphisms and environment factors with susceptibility to ischemic stroke in a Han Chinese Population

Aims

To investigate the association of several single nucleotide polymorphisms (SNPs) within ACYP2 gene and additional gene- environment interaction with ischemic stroke (IS) risk in a Chinese population.

Results

IS risk was significantly higher in carriers with the G allele of rs11896604 than those with CC genotype (CG or GG versus CC), adjusted OR (95%CI) =1.60 (1.18-2.20), and higher in carriers with the A allele of rs12615793 than those with GG genotype (GA or AA versus GG), adjusted OR (95%CI) = 1.66 (1.24-2.15). GMDR model shown a significant two-locus model (p = 0.0010) involving rs11896604 and alcohol drinking, and a significant two-locus model (p = 0.0010) involving rs12615793 and smoking. Current smokers with rs12615793- GA or AA genotype have the highest IS risk, compared to never- smokers with rs12615793-GG genotype, OR (95%CI) = 2.72 (1.64-3.86); current drinkers with rs11896604-CG or GG genotype have the highest IS risk, compared to never- drinkers with rs11896604-CC genotype, OR (95%CI) = 2.51 (1.70-3.40).

Materials and Methods

A total of 1202 participants (660 males, 542 females) were selected, including 600 IS patients and 602 control participants. The mean age of all participants was 68.2 ± 15.8 years. Generalized multifactor dimensionality reduction (GMDR) was used to screen the best interaction combination. Logistic regression was performed to investigate the impact of 4 SNPs within ACYP2 gene, additional gene-smoking or drinking interaction on IS risk.

Conclusions

We found that the G allele of rs11896604 and the A allele of rs12615793 within ACYP2 gene, rs12615793- smoking interaction, and rs11896604-alcohol drinking interaction were all associated with increased IS risk.

Moderate-to-severe obstructive sleep apnea is associated with telomere lengthening

Obstructive sleep apnea (OSA) is associated with cardiometabolic diseases. Telomere shortening is linked to hypertension, diabetes mellitus, and cardiovascular diseases. Because these conditions are highly prevalent in OSA, we hypothesized that telomere length (TL) would be reduced in OSA patients. We identified 106 OSA and 104 non-OSA subjects who underwent polysomnography evaluation. Quantitative PCR was used to measure telomere length in genomic DNA isolated from peripheral blood samples. The association between OSA and TL was determined using unadjusted and adjusted linear models. There was no difference in TL between the OSA and non-OSA (control) group. However, we observed a J-shaped relationship between TL and OSA severity: the longest TL in moderate-to-severe OSA [4,918 ± 230 (SD) bp] and the shortest TL in mild OSA (4,735 ± 145 bp). Mean TL in moderate-to-severe OSA was significantly longer than in the control group after adjustment for age, sex, body mass index, hypertension, dyslipidemia, and depression (β = 96.0, 95% confidence interval: 15.4-176.6, P = 0.020). In conclusion, moderate-to-severe OSA is associated with telomere lengthening. Our findings support the idea that changes in TL are not unidirectional processes, such that telomere shortening occurs with age and disease but may be prolonged in moderate-to-severe OSA.NEW & NOTEWORTHY Here, we show that moderate-to-severe obstructive sleep apnea is associated with longer telomeres, independent of age and cardiovascular risk factors, challenging the hypothesis that telomere shortening is a unidirectional process related to age/disease. A better understanding of the mechanisms underlying telomere dynamics may identify targets for therapeutic intervention in cardiovascular aging/other chronic diseases.

Aberrant telomere length and mitochondrial DNA copy number in suicide completers

Short telomere length (TL) occurs in individuals under psychological stress, and with various psychiatric diseases. Recent studies have also reported mitochondrial DNA copy number (mtDNAcn) alterations under several neuropsychiatric conditions. However, no study has examined whether aberrant TL or mtDNAcn occur in completed suicide, one of the most serious outcomes of mental illnesses. TL and mtDNAcn in post-mortem samples from 528 suicide completers without severe physical illness (508 peripheral bloods; 20 brains) and 560 samples from control subjects (peripheral bloods from 535 healthy individuals; 25 post-mortem brains) were analysed by quantitative polymerase chain reaction. Suicide completers had significantly shorter TL and higher mtDNAcn of peripheral bloods with sex/age-dependent differences (shorter TL was more remarkably in female/young suicides; higher mtDNAcn more so in male/elderly suicides). The normal age-related decline of TL and mtDNAcn were significantly altered in suicide completers. Furthermore, shorter TL and lower mtDNAcn of post-mortem prefrontal cortex were seen in suicide completers compared to controls. This study shows the first association of aberrant telomeres and mtDNA content with suicide completion. Our results indicate that further research on telomere shortening and mitochondrial dysfunction may help elucidate the molecular underpinnings of suicide-related pathophysiology.

Short telomere length is associated with renal impairment in Japanese subjects with cardiovascular risk

INTRODUCTION

Short telomere length has been suggested to be associated with atherosclerotic changes in Western populations. We examined the relationships between leukocyte telomere length and cardiovascular and renal function in a Japanese cohort.

PARTICIPANTS AND METHODS

We enrolled 770 subjects who each had at least one cardiovascular risk factor. The mean age was 59.5 ± 12.2 years; mean BMI was 25.1 ± 4.6 kg/m2. We measured leukocyte telomere length (LTL) by quantitative PCR (T/S ratio), and measured other biomarkers from blood and urine samples. In addition, we assessed surrogate markers of arterial stiffness, cardiovascular organ damage and kidney function, including flow-mediated vasodilation (FMD), pulse wave velocity (PWV), carotid artery augmentation index (CAAI), and urinary albumin creatinine ratio (UACR) and eGFR.

RESULTS

Leukocyte telomere length (T/S ratio) was inversely associated with age (r = -0.194, P<0.001), and was lower in men (1.13 ± 0.29%) than in women (1.20 ± 0.31%, P = 0.002). T/S ratio was positively associated with BMI in women (r = 0.11, P = 0.047), but not in men. LTL did not show a significant relationship to cardiovascular surrogate markers, including arterial stiffness, FMD, and PWV, but did show some relationship to CAAI, which was inversely associated with T/S ratio only in men (r = -0.159, P = 0.015). LTL did show a significant positive association with renal function measured by eGFR (r = 0.16, P<0.001) both in men and women.

CONCLUSIONS

In this Japanese sample of persons with increased cardiovascular risk, telomere length showed a relationship of longer telomere length to better renal function, but did not overall show convincing association with cardiovascular measures of arterial stiffness and target organ damage.

Association of ACYP2 and TSPYL6 Genetic Polymorphisms with Risk of Ischemic Stroke in Han Chinese Population

The development of ischemic stroke is associated with advanced age. Telomere length, as a marker of biological aging, has been reported to influence the risk of several age-related diseases, including ischemic stroke. Recent studies have identified the genetic variant within ACYP2 and TSPYL6 associated with shorter telomere length. The objective of this study is to investigate the putative association of ischemic stroke with common polymorphisms in ACYP2 and TSPYL6 genes in a Chinese Han population. We found that the risk alleles of six single nucleotide polymorphisms (SNPs), including rs11125529, rs12615793, rs843711, rs11896604, and rs843706 within both ACYP2 and TSPYL6, and rs17045754 in ACYP2 gene, were related with increased risk of ischemic stroke according to both allelic and genotype association analyses. The significant correlations between ACYP2 and TSPYL6 SNPs and ischemic stroke risk were also observed in dominant, recessive, and additive models, respectively. Two blocks in high linkage disequilibrium were identified in this study, and two haplotypes were associated with higher ischemic stroke susceptibility. In conclusion, the genetic polymorphisms of ACYP2 and TSPYL6 are associated with increased risk of developing ischemic stroke. Further studies with larger sample sizes are required to validate our findings.

Short Leukocyte Telomere Length Is Associated With Cardioembolic Stroke Risk in Patients With Atrial Fibrillation

BACKGROUND AND PURPOSE

The risk of cardioembolic stroke in patients with atrial fibrillation (AF) cannot be accurately assessed and novel tools are needed to improve prediction. We hypothesize that telomere shortening constitutes a novel risk factor for cardioembolic stroke in patients with AF.

METHODS

The peripheral blood leukocyte telomere length (LTL) was determined by real-time polymerase chain reaction in 187 patients with AF, 93 of them without stroke history and 94 of them having suffered 1 cardioembolic stroke. Percentiles were calculated according to LTL values in the nonstroke group to estimate the cardioembolic stroke risk associated with LTL using logistic regression models.

RESULTS

Short LTL values were independently and dose-dependently associated with an increased risk of cardioembolic stroke, with an odds ratio (95% confidence interval) of 2.93 (1.24-6.94) and 6.26 (2.01-19.52), respectively, for sex, hypertension, diabetes mellitus, heart failure, and age-adjusted models using the LTL 10th and 5th percentile cut-offs, respectively.

CONCLUSIONS

Telomere shortening is associated with cardioembolic stroke risk in patients with AF. Prospective studies are encouraged to establish the value of LTL to improve prediction tools to categorize cardioembolic stroke risk in AF.

Association Between Shortened Leukocyte Telomere Length and Cardiometabolic Outcomes

Background—

Telomeres are repetitive, gene-poor regions that cap the ends of DNA and help maintain chromosomal integrity. Their shortening is caused by inflammation and oxidative stress within the cellular environment and ultimately leads to cellular senescence. Shortened leukocyte telomere length is hypothesized to be a novel biomarker for age and age-related diseases, yet reports on its association with cardiometabolic outcomes in the literature are conflicting.

Methods and Results—

MEDLINE (1966 to present) and EMBASE (1980 to present) were last searched on September 9, 2013. Reference lists of retrieved citations were hand searched for relevant studies. No restrictions were placed on sample size, language, or publication type or date. Fifteen cohort and 12 case–control studies reporting the association between leukocyte telomere length and stroke, myocardial infarction, and type 2 diabetes mellitus were independently selected for inclusion by 2 reviewers. Data extraction and risk of bias assessment were completed independently by 2 reviewers using predefined criteria. Studies were pooled using the generic inverse variance method and both fixed and random effects models. A 1-SD decrease in leukocyte telomere length was significantly associated with stroke (odds ratio, 1.21; 95% confidence interval, 1.06–1.37; I 2 =61%), myocardial infarction (odds ratio, 1.24; 95% confidence interval, 1.04–1.47; I 2 =68%), and type 2 diabetes mellitus (odds ratio, 1.37; 95% confidence interval, 1.10–1.72; I 2 =91%). Stratification by measurement technique, study design, study size, and ethnicity explained heterogeneity in certain cardiometabolic outcomes.

Conclusions—

Shortened leukocyte telomere length demonstrates a significant association with stroke, myocardial infarction, and type 2 diabetes mellitus. Larger, well-designed studies are needed to confirm these findings and explore sources of heterogeneity.

Comparison of telomere length in black and white teachers from South Africa: the sympathetic activity and ambulatory blood pressure in Africans study

OBJECTIVE

Telomere length is a marker of biological aging that has been linked to cardiovascular disease risk. The black South African population is witnessing a tremendous increase in the prevalence of cardiovascular disease, part of which might be explained through urbanization. We compared telomere length between black South Africans and white South Africans and examined which biological and psychosocial variables played a role in ethnic difference in telomere length.

METHODS

We measured leukocyte telomere length in 161 black South African teachers and 180 white South African teachers aged 23 to 66 years without a history of atherothrombotic vascular disease. Age, sex, years having lived in the area, human immunodeficiency virus (HIV) infection, hypertension, body mass index, dyslipidemia, hemoglobin A1c, C-reactive protein, smoking, physical activity, alcohol abuse, depressive symptoms, psychological distress, and work stress were considered as covariates.

RESULTS

Black participants had shorter (median, interquartile range) relative telomere length (0.79, 0.70-0.95) than did white participants (1.06, 0.87-1.21; p < .001), and this difference changed very little after adjusting for covariates. In fully adjusted models, age (p < .001), male sex (p = .011), and HIV positive status (p = .023) were associated with shorter telomere length. Ethnicity did not significantly interact with any covariates in determining telomere length, including psychosocial characteristics.

CONCLUSIONS

Black South Africans showed markedly shorter telomeres than did white South African counterparts. Age, male sex, and HIV status were associated with shorter telomere length. No interactions between ethnicity and biomedical or psychosocial factors were found. Ethnic difference in telomere length might primarily be explained by genetic factors.

Leukocyte telomere length and hemostatic factors in a South African cohort: the SABPA Study

BACKGROUND

Incident atherothrombotic disease is predicted by leukocyte telomere length, a marker of biological age, and hemostatic factor levels, indicating a hypercoagulable state. We hypothesized that shorter telomeres are associated with elevated circulating levels of hemostatic factors.

METHODS

We examined 171 South African (black) and 182 Caucasian (white) schoolteachers (mean age ± standard deviation, 48.5 ± 9.0 years; 50.4% women). Levels of fibrinogen, von Willebrand factor antigen (VWF:Ag), D-dimer and plasminogen activator inhibitor-1 antigen (PAI-1:Ag) were measured in plasma, and values were log-transformed before analysis. Relative average telomere length (content of telomere PCR product/content of human β-globin PCR product ratio, i.e. telomere/single-copy gene ratio) was assessed with multiplex quantitative real-time PCRs. Multivariate analyses included demographics, metabolic factors, health behavior, and medication.

RESULTS

Africans had shorter mean telomere length (0.82, 95% confidence interval [CI] 0.79-0.86 vs. 1.07, 95% CI 1.04-1.10) and higher fibrinogen (B = 0.085, 95% CI 0.061-0.109) and PAI-1:Ag (B = 0.255, 95% CI 0.206-0.303) levels, but lower VWF:Ag levels (B = - 0.059, 95% CI - 0.089 to - 0.028), than Caucasians. Shorter telomeres were associated with higher fibrinogen (B = - 0.045, 95% CI - 0.088 to - 0.001), VWF:Ag (B = - 0.137, 95% CI - 0.193 to - 0.081) and D-dimer (B = - 0.201, 95% CI - 0.377 to - 0.025) levels, conditional on ethnicity. An interaction emerged between ethnicity and telomere length for VWF:Ag level; that is, shorter telomeres were associated with higher VWF:Ag levels in Caucasians (B = - 0.170, 95% CI - 0.232 to - 0.108) but not in Africans.

CONCLUSIONS

Shorter telomeres were associated with increased levels of several hemostatic factors after adjustment for confounding variables, whereby ethnicity partially moderated this effect. A relationship between accelerated biological aging and hypercoagulability might contribute to the risk of premature atherothrombotic events.

WITHDRAWN: Telomeres and atherosclerosis

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Leucocyte telomere length and risk of cardiovascular disease: systematic review and meta-analysis

OBJECTIVE

To assess the association between leucocyte telomere length and risk of cardiovascular disease.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Studies published up to March 2014 identified through searches of Medline, Web of Science, and Embase.

ELIGIBILITY CRITERIA

Prospective and retrospective studies that reported on associations between leucocyte telomere length and coronary heart disease (defined as non-fatal myocardial infarction, coronary heart disease death, or coronary revascularisation) or cerebrovascular disease (defined as non-fatal stroke or death from cerebrovascular disease) and were broadly representative of general populations--that is, they did not select cohort or control participants on the basis of pre-existing cardiovascular disease or diabetes.

RESULTS

Twenty four studies involving 43,725 participants and 8400 patients with cardiovascular disease (5566 with coronary heart disease and 2834 with cerebrovascular disease) were found to be eligible. In a comparison of the shortest versus longest third of leucocyte telomere length, the pooled relative risk for coronary heart disease was 1.54 (95% confidence interval 1.30 to 1.83) in all studies, 1.40 (1.15 to 1.70) in prospective studies, and 1.80 (1.32 to 2.44) in retrospective studies. Heterogeneity between studies was moderate (I(2) = 64%, 41% to 77%, Phet<0.001) and was not significantly explained by mean age of participants (P = 0.23), the proportion of male participants (P = 0.45), or distinction between retrospective versus prospective studies (P = 0.32). Findings for coronary heart disease were similar in meta-analyses restricted to studies that adjusted for conventional vascular risk factors (relative risk 1.42, 95% confidence interval 1.17 to 1.73); studies with ≥ 200 cases (1.44, 1.20 to 1.74); studies with a high quality score (1.53, 1.22 to 1.92); and in analyses that corrected for publication bias (1.34, 1.12 to 1.60). The pooled relative risk for cerebrovascular disease was 1.42 (1.11 to 1.81), with no significant heterogeneity between studies (I(2) = 41%, 0% to 72%, Phet = 0.08). Shorter telomeres were not significantly associated with cerebrovascular disease risk in prospective studies (1.14, 0.85 to 1.54) or in studies with a high quality score (1.21, 0.83 to 1.76).

CONCLUSION

Available observational data show an inverse association between leucocyte telomere length and risk of coronary heart disease independent of conventional vascular risk factors. The association with cerebrovascular disease is less certain.

Targets of immune regeneration in rheumatoid arthritis

Many of the aging-related morbidities, including cancer, cardiovascular disease, neurodegenerative disease, and infectious susceptibility, are linked to a decline in immune competence with a concomitant rise in proinflammatory immunity, placing the process of immune aging at the center of aging biology. Immune aging affects individuals older than 50 years and is accelerated in patients with the autoimmune disease rheumatoid arthritis. Immune aging results in a marked decline in protective immune responses and a parallel increase in tissue inflammatory responses. By studying immune cells in patients with rheumatoid arthritis, several of the molecular underpinnings of the immune aging process have been delineated, such as the loss of telomeres and inefficiencies in the repair of damaged DNA. Aging T cells display a series of abnormalities, including the unopposed up-regulation of cytoplasmic phosphatases and the loss of glycolytic competence, that alter their response to stimulating signals and undermine their longevity. Understanding the connection between accelerated immune aging and autoimmunity remains an area of active research. With increasing knowledge of the molecular pathways that cause immunosenescence, therapeutic interventions can be designed to slow or halt the seemingly inevitable deterioration of protective immunity with aging.

Telomere shortening unrelated to smoking, body weight, physical activity, and alcohol intake: 4,576 general population individuals with repeat measurements 10 years apart

Cross-sectional studies have associated short telomere length with smoking, body weight, physical activity, and possibly alcohol intake; however, whether these associations are due to confounding is unknown. We tested these hypotheses in 4,576 individuals from the general population cross-sectionally, and with repeat measurement of relative telomere length 10 years apart. We also tested whether change in telomere length is associated with mortality and morbidity in the general population. Relative telomere length was measured with quantitative polymerase chain reaction. Cross-sectionally at the first examination, short telomere length was associated with increased age (P for trend across quartiles = 3 × 10(-77)), current smoking (P = 8 × 10(-3)), increased body mass index (P = 7 × 10(-14)), physical inactivity (P = 4 × 10(-17)), but not with increased alcohol intake (P = 0.10). At the second examination 10 years later, 56% of participants had lost and 44% gained telomere length with a mean loss of 193 basepairs. Change in leukocyte telomere length during 10 years was associated inversely with baseline telomere length (P<1 × 10(-300)) and age at baseline (P = 1 × 10(-27)), but not with baseline or 10-year inter-observational tobacco consumption, body weight, physical activity, or alcohol intake. Prospectively during a further 10 years follow-up after the second examination, quartiles of telomere length change did not associate with risk of all-cause mortality, cancer, chronic obstructive pulmonary disease, diabetes mellitus, ischemic cerebrovascular disease, or ischemic heart disease. In conclusion, smoking, increased body weight, and physical inactivity were associated with short telomere length cross-sectionally, but not with telomere length change during 10 years observation, and alcohol intake was associated with neither. Also, change in telomere length did not associate prospectively with mortality or morbidity in the general population.

Lack of causal relationship between leukocyte telomere length and coronary heart disease

OBJECTIVE

To investigate the association between genetic variation in telomerase RNA component (TERC) and leukocyte telomere length (LTL) with risk of coronary heart disease (CHD).

METHODS AND RESULTS

An analysis of LTL was conducted, focusing on two SNPs in 2 community-based cohort populations comprising 3500 Chinese Han individuals. In addition, LTL ratio was determined in a case-control setting involving 4351 participants: 2211 healthy individuals and 2140 CHD patients. The association between LTL and the presence and extent of cardiovascular and cerebrovascular lesions were tested. Results confirmed the association of rs12696304 and rs16847897 with LTL in the Chinese Han population (P=1.63×10(-6) and P=1.44×10(-7), respectively). However, these SNPs confer a moderate risk for CHD but did not achieve significant threshold after multiple corrections. Decreased LTL ratio was associated with CHD (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.02-1.34; P<0.01). In addition, the LTL ratio in CHD patients was related to numbers of vascular disease lesions.

CONCLUSIONS

Our results do not support a causal role of LTL for the development of CHD. However, LTL may be related to complex conditions associated with cardiovascular and cerebrovascular disease manifestations.

Telomeres and cardiovascular disease risk: an update 2013

Leukocyte telomere length (LTL) has been regarded as a potential marker of biologic aging because it usually shortens in a predictable way with age. Recently, a growing interest in cardiovascular aging has led to a number of new epidemiologic studies investigating LTL in various disease conditions. Some methodological problems exist because there are different methods available to determine LTL, and standardization is much needed. For example, in the majority of studies, patients with early-onset coronary heart disease have been shown to have shorter LTL. In addition, patients with diabetes mellitus complications tend to have shorter LTL than control subjects. On the other hand, increased left ventricular hypertrophy or mass is associated with longer LTL, and studies investigating hypertension have reported both shorter and longer LTL than found in normotensive control subjects. There is, therefore, a need for longitudinal studies to elucidate these complicated relationships further, to provide estimations of telomere attrition rates, and to overcome analytical problems when only cross-sectional studies are used. The understanding of cardiovascular aging and telomere biology may open up new avenues for interventions, such as stem cell therapy or agents that could retard this aging process over and beyond conventional risk factor control.

Association between telomere length and type 2 diabetes mellitus: a meta-analysis

Background

Several epidemiological studies have examined the association between shortened telomere length and type 2 diabetes mellitus (T2DM), while the results remained conflicting. We conducted a meta-analysis to derive a more precise estimation of the relationship between them.

Methods

We systematically reviewed the databases of PubMed, EMBASE, and Web of Science for all studies on the association between telomere length and T2DM. We conducted this study assessed by STATA 11.0. Data were summarized using random-effects or fixed-effects meta-analysis. The heterogeneity and publication bias among studies were examined by using χ²-based Q statistic test and Egger’s test, respectively.

Results

Nine cohorts consisting of 5759 cases and 6518 controls were selected into the meta-analysis. The results indicated that shortened telomere length was significantly associated with T2DM risk (OR: 1.291; 95% CI: 1.112, 1.498; P<0.001) with heterogeneity (I² = 71.6%). When three cohorts responsible for the heterogeneity were excluded, the pooled OR for the remaining cohorts indicated a significant association between shortened telomere length and T2DM (OR: 1.117; 95% CI: 1.002, 1.246; P = 0.045) without heterogeneity.

Conclusion

We found a statistically significant association between shortened telomere length and T2DM.

Telomeres and human health

Telomeres are the tips of chromosomes and consist of proteins and hexanucleotide tandem repeats of DNA. The DNA repeats are shortened at each mitotic division of normal cells, and the telomere length chronicles how many divisions the cell has undergone. Thus, telomere length is a marker of fundamental biological pathways. It has been possible to measure telomere length for more than 20 years, and it has been established that telomere length is associated with age, sex and lifestyle factors. Here, the current knowledge of telomere length as a biomarker of disease susceptibility and mortality will be reviewed. In addition, technical difficulties and the reasons why measurement of telomeres has still not been introduced into routine clinical practice will be discussed. Findings from recent studies conducted in many thousands of individuals indicate that telomere length is not-or at best only marginally-independently associated with risk of common disorders such as cardiovascular, pulmonary and neoplastic diseases. However, in sufficiently powered studies, short telomeres are repeatedly and independently found to be associated with increased risk of early death in the general population or in subsets of individuals. This indicates that measurement of telomeres could be a valuable prognostic biomarker in many clinical settings. However, whether short telomeres are a causal factor for or simply a marker of increased risk of early death must be determined. Finally, how Mendelian randomization studies could clarify this issue, and which clinical studies might be carried out to refine this very promising biomarker for routine clinical use will be considered.