Effect of obesity on telomere length: Systematic review and meta-analysis

Causal association and shared genetics between telomere length and COVID-19 outcomes: New evidence from the latest large-scale summary statistics

Background

Observational studies suggested that leukocyte telomere length (LTL) is shortened in COVID-19 patients. However, the genetic association and causality remained unknown.

Methods

Based on the genome-wide association of LTL (N = 472,174) and COVID-19 phenotypes (N = 1086,211-2597,856), LDSC and SUPERGNOVA were used to estimate the genetic correlation. Cross-trait GWAS meta-analysis, colocalization, fine-mapping analysis, and transcriptome-wide association study were conducted to explore the shared genetic etiology. Mendelian randomization (MR) was utilized to infer the causality. Upstream and downstream two-step MR was performed to investigate the potential mediating effects.

Results

LDSC identified a significant genetic association between LTL and all COVID-19 phenotypes (rG < 0, p < 0.05). Six significant regions were observed for LTL and COVID-19 susceptibility and hospitalization, respectively. Colocalization analysis found rs144204502, rs34517439, and rs56255908 were shared causal variants between LTL and COVID-19 phenotypes. Numerous biological pathways associated with LTL and COVID-19 outcomes were identified, mainly involved in -immune-related pathways. MR showed that longer LTL was significantly associated with a lower risk of COVID-19 severity (OR [95% CI] = 0.81 [0.71-0.92], p = 1.24 ×10-3) and suggestively associated with lower risks of COVID-19 susceptibility (OR [95% CI] = 0.96 [0.92-1.00], p = 3.44 ×10-2) and COVID-19 hospitalization (OR [95% CI] = 0.89 [0.80-0.98], p = 1.89 ×10-2). LTL partially mediated the effects of BMI, smoking, and education on COVID-19 outcomes. Furthermore, six proteins partially mediated the causality of LTL on COVID-19 outcomes, including BNDF, QPCT, FAS, MPO, SFTPB, and APOF.

Conclusions

Our findings suggested that shorter LTL was genetically associated with a higher risk of COVID-19 phenotypes, with shared genetic etiology and potential causality.

Pre-pregnancy BMI, gestational weight gain, and telomere length in amniotic fluid: a causal graph analysis

Previous investigations have suggested a potential association between pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) with telomere length (TL) in various tissues of pregnant women and newborns. Nonetheless, as association does not imply causation, our objective was to investigate the causal connections among pre-pregnancy BMI, GWG, and TL in amniotic fluid. The analysis included 136 mother-child pairs from the Mamma & Bambino cohort, and three causal graph models were developed to depict the interconnections between pre-pregnancy BMI, GWG, and TL. Causal graph analysis was conducted utilizing the do-operator to estimate the causal effect of GWG and the controlled direct effect of pregestational BMI. We revealed that transitioning from non-adequate to adequate GWG had a positive impact on the probability of having "long" TL (i.e., a value greater than the population median) in all three models. When considering the effect of pre-pregnancy BMI, the highest probability of "long" TL was observed in normal weight women with adequate GWG. In contrast, the effect of adequate GWG became minimal among overweight women. These results shed light on the potential causality between pre-pregnancy BMI, GWG, and TL in amniotic fluid, emphasizing the importance of appropriate weight management before and during pregnancy for optimal TL outcomes.

Associations of childhood and adulthood body size, and child-to-adult body size change with adult telomere length

AIM

To comprehensively examine the associations of childhood and adulthood body size, and child-to-adult body size change with adult leucocyte telomere length (LTL).

METHODS

We included 453 602 participants from the UK Biobank. Childhood body size at the age of 10 years was collected through a questionnaire. Adulthood body size was assessed using body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), fat mass index (FMI), and fat-free mass index (FFMI).

RESULTS

Individuals with plumper body size in childhood exhibited shorter LTL in adulthood (-0.0086 [-0.0017, -0.0004]). Adulthood BMI (-0.0286 [-0.0315, -0.0258]), WC (-0.0271 [-0.0303, -0.0238]), WHR (-0.0269 [-0.0308, -0.0230]) and FMI (-0.0396 [-0.0438, -0.0351]) were negatively associated with LTL, whereas FFMI (0.0095 [0.0039, 0.0152]) was positively associated with LTL. Compared to individuals consistently having an average/normal weight in both childhood and adulthood, those who maintained or developed overweight/obesity from childhood to adulthood had a shorter adult LTL, regardless of childhood body size. Notably, the LTL shortening effect was not observed in individuals with plumper body size in childhood but normal weight in adulthood.

CONCLUSIONS

Childhood and adulthood obesity are both associated with LTL shortening in adulthood. Transitioning to or maintaining overweight/obese status from childhood to adulthood is associated with shorter adult LTL, whereas this effect can be reversed if plumper children become normal weight.

Autophagy in aging-related diseases and cancer: Principles, regulatory mechanisms and therapeutic potential

Macroautophagy/autophagy is primarily accountable for the degradation of damaged organelles and toxic macromolecules in the cells. Regarding the essential function of autophagy for preserving cellular homeostasis, changes in, or dysfunction of, autophagy flux can lead to disease development. In the current paper, the complicated function of autophagy in aging-associated pathologies and cancer is evaluated, highlighting the underlying molecular mechanisms that can affect longevity and disease pathogenesis. As a natural biological process, a reduction in autophagy is observed with aging, resulting in an accumulation of cell damage and the development of different diseases, including neurological disorders, cardiovascular diseases, and cancer. The MTOR, AMPK, and ATG proteins demonstrate changes during aging, and they are promising therapeutic targets. Insulin/IGF1, TOR, PKA, AKT/PKB, caloric restriction and mitochondrial respiration are vital for lifespan regulation and can modulate or have an interaction with autophagy. The specific types of autophagy, such as mitophagy that degrades mitochondria, can regulate aging by affecting these organelles and eliminating those mitochondria with genomic mutations. Autophagy and its specific types contribute to the regulation of carcinogenesis and they are able to dually enhance or decrease cancer progression. Cancer hallmarks, including proliferation, metastasis, therapy resistance and immune reactions, are tightly regulated by autophagy, supporting the conclusion that autophagy is a promising target in cancer therapy.

Leukocyte telomere length in subjects with metabolic dysfunction-associated steatotic liver disease

BACKGROUND AND STUDY AIMS

This study aimed to examine the association between peripheral leukocyte telomere length and indicators of metabolic abnormalities in subjects with metabolic dysfunction-associated steatotic liver disease (MASLD) assessed by magnetic resonance imaging (MRI).

PATIENTS AND METHODS

This cross-sectional study included adults over 20 years with body mass index (BMI) of over >25 kg/m2 and sonographic evidence of hepatic steatosis. The subjects were evaluated by clinical and biochemical variables, determination of hepatic fat fraction by MRI and relative peripheral leukocyte telomere length by quantitative real-time polymerase chain reaction.

RESULTS

Thirty-two subjects (22 men and 10 women) with MASLD were included, with a median age of 40 years, median BMI of 33.75 kg/m2, median HFF 19 %, and median relative T/S ratio of 0.64. Subjects with relative T/S ratio below the median had significantly higher age, lower BMI, higher AST serum levels, higher GGT serum levels, lower serum ferritin levels, and higher FIB4 score. In a multivariable logistic regression model considering relative T/S ratio below or above the median only age was significantly associated with relative T/S ratio. Our findings suggest that age is the most important factor associated with telomere length among subjects with MASLD.

CONCLUSION

Our findings suggest that age is the most important factor associated with telomere length among subjects with MASLD.

The association of metabolic syndrome with telomere length as a marker of cellular aging: a systematic review and meta-analysis

Background

It has been suggested that metabolic syndrome (MetS) accelerates the aging process, potentially contributing to the development of age-related complications. Available studies examining the relation of MetS to telomere length (TL), a putative biological marker of aging, have yielded inconclusive findings. This meta-analysis was performed to investigate the association between MetS and TL.

Methods

A comprehensive systematic search was conducted in PubMed and Scopus databases to identify relevant literature published up to February 2024. Standard mean difference (SMD) and standardized beta coefficient (β) with their 95% confidence intervals (CI) were used as effect sizes to measure the associations using the random effects model.

Results

A total of nine studies, comprising a total sample size of 8,606 participants, were eligible for the meta-analysis. No significant difference in mean TL was found between patients with and without MetS (SMD = -0.03, 95%CI = -0.17 to 0.10), with a significant heterogeneity across the studies (I 2 = 89.7.0%, p ≤ 0.001). In contrast, it was revealed that MetS is negatively related to TL (β = -0.08, 95%CI = -0.15 to -0.004). In the subgroup analysis, this finding was supported by the International Diabetes Federation (IDF) definition of MetS.

Conclusion

This meta-analysis highlighted that MetS may be linked to a shorter TL. Additional studies are required to confirm this finding.

Effect of long-term caloric restriction on telomere length in healthy adults: CALERIE™ 2 trial analysis

Caloric restriction (CR) modifies lifespan and aging biology in animal models. The Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE™) 2 trial tested translation of these findings to humans. CALERIE™ randomized healthy, nonobese men and premenopausal women (age 21-50y; BMI 22.0-27.9 kg/m2), to 25% CR or ad-libitum (AL) control (2:1) for 2 years. Prior analyses of CALERIE™ participants' blood chemistries, immunology, and epigenetic data suggest the 2-year CR intervention slowed biological aging. Here, we extend these analyses to test effects of CR on telomere length (TL) attrition. TL was quantified in blood samples collected at baseline, 12-, and 24-months by quantitative PCR (absolute TL; aTL) and a published DNA-methylation algorithm (DNAmTL). Intent-to-treat analysis found no significant differences in TL attrition across the first year, although there were trends toward increased attrition in the CR group for both aTL and DNAmTL measurements. When accounting for adherence heterogeneity with an Effect-of-Treatment-on-the-Treated analysis, greater CR dose was associated with increased DNAmTL attrition during the baseline to 12-month weight-loss period. By contrast, both CR group status and increased CR were associated with reduced aTL attrition over the month 12 to month 24 weight maintenance period. No differences were observed when considering TL change across the study duration from baseline to 24-months, leaving it unclear whether CR-related effects reflect long-term detriments to telomere fidelity, a hormesis-like adaptation to decreased energy availability, or measurement error and insufficient statistical power. Unraveling these trends will be a focus of future CALERIE™ analyses and trials.

Obesity contributes to telomere shortening in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a multifactorial disorder and obesity occurs in 38% to 88% of these women. Although hyperandrogenism may contribute to telomere lengthening, increased body mass index (BMI) is associated with telomere erosion. We sought to compare leukocyte telomere length (LTL) in PCOS women with normal, overweight, and obese BMI. We evaluated the relationship between LTL and clinical variables of PCOS and inflammatory biomarkers independent of BMI. A total of 348 women (243 PCOS and 105 non-PCOS) were evaluated for anthropometric measures, total testosterone, androstenedione, estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone-binding globulin (SHBG), free androgen index (FAI), fasting insulin and glycemia, lipid profile, homocysteine, C-reactive protein (CRP) and homeostatic model of insulin resistance (HOMA-IR). LTL was measured by qPCR. The PCOS group presented higher weight, waist circumference, BMI, testosterone, LH, fasting insulin, FAI, and HOMA-IR, and lower E2, SHBG, and fasting glycemia measures compared with the non-PCOS. When stratified by BMI, LTL was increased in all subgroups in PCOS compared to non-PCOS. However, in the PCOS group, LTL was lower in overweight (P = 0.0187) and obese (P = 0.0018) compared to normal-weight women. The generalized linear model showed that BMI, androstenedione, homocysteine, and CRP were associated with telomere biology. Women with PCOS had longer LTL, however, overweight or obesity progressively contributes to telomere shortening and may affect reproductive outcomes of PCOS, while androstenedione may increase LTL.

Association between maternal depression symptoms and child telomere length

The biological mechanisms that explain how adverse early life events influence adult disease risk are poorly understood. One proposed mechanism is via the induction of accelerated biological aging, for which telomere length is considered a biomarker. We aimed to determine if maternal depression pre- and post-partum was associated with telomere length in children at 4 years of age (n = 4299). Mothers completed structured questionnaires assessing depression during pregnancy (Edinburgh Depression Scale), at 9 months (Edinburgh Depression Scale), and at 54 months postpartum (Patient Health Questionnaire 9). Regression methods were used to investigate the relationship between telomere length (DNA from saliva) and maternal depression score recorded at each stage. Significant covariates included in the final model were: maternal age at pregnancy; child sex; child ethnicity; gestational age group, and rurality group. Child telomere length was found to be longer if their mother had a higher depression score at both postpartum time points tested (9 months of age; coefficient 0.003, SE = 0.001, P = 0.01, 54 months of age; coefficient 0.003, SE = 0.002, P = 0.02). Although these findings seem paradoxical, increased telomere length may be an adaptive response to early life stressors. We propose several testable hypotheses for these results and to determine if the positive association between depression and telomere length is a developmental adaptation or an indirect consequence of environmental factors.

Associations between weight-adjusted-waist index and telomere length: Results from NHANES: An observational study

Previous studies have demonstrated the connection between obesity and telomere length. A recently devised metric for determining obesity, the weight-adjusted-waist index (WWI), offers a distinct advantage in predicting fat and lean mass by depicting weight-independent abdominal adiposity. This article presents the results of the inaugural study on the relationship between WWI and telomere length in adult populations. The cross-sectional investigation analyzed data from 3479 participants from the National Health and Nutrition Examination Survey (NHANES) conducted from 1999 to 2000. To inspect linear and nonlinear correlations, we adopted weighted multiple logistic regression analysis and smooth curve fit, respectively. In addition, threshold effects and subgroup analyses were accomplished. In the fully adapted model, a significant adverse association of WWI with telomere length was detected [β = -0.02, 95% CI: (-0.03, -0.00), P value = 0.01]. The adverse correlation remained consistent across all subcategories. We also discovered an inverted U-shaped curve linking WWI and telomere length, with a conspicuous inflection point of 10.07 cm/√kg. For the first time, our research demonstrated strong links between WWI and telomere length. The inflection point suggests that controlling WWI within an optimum range might be essential for aging and health.

Effects of Age and Biological Age-Determining Factors on Telomere Length in Type 2 Diabetes Mellitus Patients

Background and Objectives: Telomere length (TL) undergoes attrition over time, indicating the process of aging, and is linked to a higher risk of diabetes mellitus type 2 (DM-2). This molecular epidemiological study investigated the correlation between leukocyte TL variations and determinants of molecular aging in 121 Pakistani DM-2 patients. Materials and Methods: The ratio of telomere repeats to the SCG copy number was calculated to estimate the TL in each sample through qPCR assays. Results: In this study, smaller mean TLs were observed in 48.8% of males (6.35 ± 0.82 kb), 3.3% of underweight patients (5.77 ± 1.14 kb), 61.2% of patients on regular medication (6.50 ± 0.79 kb), 9.1% with very high stress levels (5.94 ± 0.99 kb), 31.4% of smokers (5.83 ± 0.73 kb), 40.5% of patients with low physical activity (6.47 ± 0.69 kb), 47.9% of hypertensive patients (5.93 ± 0.64 kb), 10.7% of patients with DM-2 for more than 15 years, and 3.3% of patients with a delayed onset of DM-2 (6.00 ± 0.93 kb). Conclusion: This research indicated a significant negative correlation (R2 = 0.143) between TL and the age of DM-2 patients. This study demonstrated that the correlation of telomere length with age in DM-2 patients was also influenced by various age-determining factors, including hypertension and smoking habits, with significant strong (R2 = 0.526) and moderate (R2 = 0.299) correlations, respectively; sex, obesity, the stress level and age at the onset of diabetes with significant weak correlations (R2 = 0.043, 0.041, 0.037, and 0.065, respectively), and no significant correlations of medication routine, rate of physical activity, and the durations of DM-2 with age-adjusted telomere length. These results challenge TL as the sole marker of aging, thus highlighting the need for further research to understand underlying factors and mitigate the effect of aging or premature aging on diabetic patients.

Causal association of obesity with epigenetic aging and telomere length: a bidirectional mendelian randomization study

BACKGROUND

In observational studies, there exists an association between obesity and epigenetic age as well as telomere length. However, varying and partially conflicting outcomes have notably arisen from distinct studies on this topic. In the present study, two-way Mendelian randomization was used to identify potential causal associations between obesity and epigenetic age and telomeres.

METHODS

A genome-wide association study was conducted using data from individuals of European ancestry to investigate bidirectional Mendelian randomization (MR) regarding the causal relationships between obesity, as indicated by three obesity indicators (body mass index or BMI, waist circumference adjusted for BMI or WCadjBMI, and waist-to-hip ratio adjusted for BMI or WHRadjBMI), and four epigenetic age measures (HannumAge, HorvathAge, GrimAge, PhenoAge), as well as telomere length. To assess these causal associations, various statistical methods were employed, including Inverse Variance Weighted (IVW), Weighted Median, MR Egger, Weighted Mode, and Simple Mode. To address the issue of multiple testing, we applied the Bonferroni correction. These methods were used to determine whether there is a causal link between obesity and epigenetic age, as well as telomere length, and to explore potential bidirectional relationships. Forest plots and scatter plots were generated to show causal associations between exposures and outcomes. For a comprehensive visualization of the results, leave-one-out sensitivity analysis plots, individual SNP-based forest plots for MR analysis, and funnel plots were included in the presentation of the results.

RESULTS

A strong causal association was identified between obesity and accelerated HannumAge, GrimAge, PhenoAge and telomere length shrinkage. The causal relationship between WCadjBMI and PhenoAge acceleration (OR: 2.099, 95%CI: 1.248-3.531, p = 0.005) was the strongest among them. However, only the p-values for the causal associations of obesity with GrimAge, PhenoAge, and telomere length met the criteria after correction using the Bonferroni multiple test. In the reverse MR analysis, there were statistically significant causal associations between HorvathAge, PhenoAge and GrimAge and BMI, but these associations exhibited lower effect sizes, as indicated by their Odds Ratios (ORs). Notably, sensitivity analysis revealed the robustness of the study results.

CONCLUSIONS

The present findings reveal a causal relationship between obesity and the acceleration of epigenetic aging as well as the reduction of telomere length, offering valuable insights for further scientific investigations aimed at developing strategies to mitigate the aging process in humans.

Changes in leukocyte telomere length among children with obesity participating in a behavioural weight control program

OBJECTIVE

To examine changes in leukocyte telomere length (LTL) during and after a behavioural weight control program for children with obesity.

METHODS

We measured LTL among a cohort of 158 children 8-12 years of age with a body mass index greater than or equal to the 95th percentile for age and sex. Children were 55% female, 29% white, 52% Latinx, 8% Asian and 11% Pacific Islander, other or multiethnic. All children participated in a 6-month, family-based, group behavioural weight control program and were assessed before treatment, after treatment and 1 year after the end of treatment. To test the sample population slope of LTL over the intervention and maintenance time periods, we fit spline mixed-effect regression models.

RESULTS

LTL increased an average of 0.09 T/S units per year (95% confidence interval [CI] 0.04 to 0.13; p = 0.0001) during the weight control program intervention period, followed by an average decline of -0.05 T/S units per year (95% CI -0.08 to -0.03; p < 0.0001) during the 1 year of follow-up after the completion of the intervention. Among 26 social, psychological, behavioural and physiological factors we examined, we did not find any predictors of these changes.

CONCLUSIONS

LTL increased in response to a behavioural weight control program among children with obesity, suggesting an impact on biological health and cellular aging from participation in a behavioural weight control intervention. LTL may be a useful biomarker for assessing changes in response to behavioural interventions.

Food Insecurity, telomere length and the potential modifying effects of social support in National Health and Nutrition Examination Survey

OBJECTIVE

Telomere length (TL) is a posited pathway through which chronic stress results in biological dysregulation and subsequent adverse health outcomes. Food insecurity is associated with shorter TL. Social support, which is defined by the size and function of an individual's social network, is associated with better health outcomes. The present study assesses whether social support modifies the relationship between food security and TL.

DESIGN

Cross-sectional study design. Linear regression was used to assess the association between food insecurity and TL, stratified by social support level. A multiplicative interacted model was used to formally test modification.

SETTING

Data come from the National Health and Nutrition Examination Survey 1999-2000 and 2001-2002 waves.

PARTICIPANTS

Adults aged 60 years and older who have measurements for TL.

RESULTS

Our sample comprised 2674 participants, and 63·5 % of the total sample had low social support, with 13·3 % being food insecure. In fully adjusted models, food insecurity was negatively though modestly associated (P = 0·13) with TL. Associations between food insecurity and TL were significantly modified by social support (interaction P = 0·026), whereby food insecurity had a stronger effect among individuals with high social support (coefficient = -0·099 (95 % CI: -0·161, -0·038)) compared to low social support (coefficient = -0·001, (95 % CI: -0·033, 0·032)).

CONCLUSION

Food insecurity is modestly associated with shorter TL. Contrary to our hypothesis, food insecurity had more deleterious effects on TL among participants with high social support than low social support. Results may indicate that the food insecure population is a higher needs population, and increased social support reflects these needs rather than providing protective effects.

Life's Essential 8: Optimizing Health in Older Adults

The population worldwide is getting older as a result of advances in public health, medicine, and technology. Older individuals are living longer with a higher prevalence of subclinical and clinical cardiovascular disease (CVD). In 2010, the American Heart Association introduced a list of key prevention targets, known as "Life's Simple 7" to increase CVD-free survival, longevity, and quality of life. In 2022, sleep health was added to expand the recommendations to "Life's Essential 8" (eat better, be more active, stop smoking, get adequate sleep, manage weight, manage cholesterol, manage blood pressure, and manage diabetes). These prevention targets are intended to apply regardless of chronologic age. During this same time, the understanding of aging biology and goals of care for older adults further enhanced the relevance of prevention across the range of functions. From a biological perspective, aging is a complex cellular process characterized by genomic instability, telomere attrition, loss of proteostasis, inflammation, deregulated nutrient-sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. These aging hallmarks are triggered by and enhanced by traditional CVD risk factors leading to geriatric syndromes (eg, frailty, sarcopenia, functional limitation, and cognitive impairment) which complicate efforts toward prevention. Therefore, we review Life's Essential 8 through the lens of aging biology, geroscience, and geriatric precepts to guide clinicians taking care of older adults.

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

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

A review and meta-analysis: Cross-tissue telomere length correlations in healthy humans

BACKGROUND AND AIM

Tissue source has been shown to exert a significant effect on the magnitude of associations between telomere length and various health outcomes and exposures. The purpose of the present qualitative review and meta-analysis is to describe and investigate the impact of study design and methodological features on the correlation between telomere lengths measured in different tissues from the same healthy individual.

METHODS

This meta-analysis included studies published from 1988 to 2022. Databases searched included PubMed, Embase, and Web of Science and studies were identified using the keywords "telomere length" and "tissues" or "tissue." A total of 220 articles of 7856 initially identified studies met inclusion criteria for qualitative review, of which 55 met inclusion criteria for meta-analysis in R RESULTS: Studies meeting inclusion criteria for meta-analysis tended to have enhanced demographic and methodological reporting relative to studies only included in the qualitative review. A total of 463 pairwise correlations reported for 4324 unique individuals and 102 distinct tissues were extracted from the 55 studies and subject to meta-analysis, resulting in a significant effect size z = 0.66 (p < 0.0001) and meta-correlation coefficient of r = 0.58. Meta-correlations were significantly moderated by sample size and telomere length measurement methodology, with studies of smaller size and those using hybridization-based analyses exhibiting the largest meta-correlation. Tissue source also significantly moderated the meta-correlation, wherein correlations between samples of a different lineage (e.g., blood vs. non-blood) or collection method (e.g., peripheral vs. surgical) were lower than correlations between samples of the same lineage or collection method.

CONCLUSION

These results suggest that telomere lengths measured within individuals are generally correlated, but future research should be intentional in selecting a tissue for telomere length measurement that is most biologically relevant to the exposure or outcome investigated and balance this with the feasibility of obtaining the sample in sufficient numbers of individuals.

The effects of exercise and diet on oxidative stress and telomere length in breast cancer survivors

PURPOSE

Cancer and its treatments accelerate biological aging. This analysis tested the hypothesis that exercise and diet reduce oxidative stress and prevent telomere shortening in breast cancer survivors.

METHODS

In a 2 × 2 factorial design, 342 breast cancer survivors who were insufficiently physically active and had overweight or obesity at enrollment were randomized to one of four treatment groups for 52 weeks: control, exercise alone, diet alone, or exercise plus diet. The endpoints of this analysis were the change from baseline to week 52 in 8-iso-prostaglandin F2α (8-iso-PGF2α) and lymphocyte telomere length.

RESULTS

Baseline telomere length was shorter than age-adjusted normative values (median difference: - 1.8 kilobases; 95% CI - 2.4, - 1.1); equivalent to 21 years (95% CI 17, 25) of accelerated chronological aging. Compared to control, exercise alone did not change 8-iso-PGF2α [9.9%; 95% confidence interval (CI) - 1.0, 20.8] or telomere length (13.8%; 95% CI - 15.6, 43.3). Compared to control, diet alone was associated with reduced 8-iso-PGF2α (- 10.5%; 95% CI - 19.5, - 1.5) but did not change telomere length (12.1%; 95% CI - 17.2, 41.3). Compared to control, exercise plus diet was associated with reduced 8-iso-PGF2α (- 9.8%; 95% CI - 18.7, - 0.9) but did not change telomere length (- 8.5%; 95% CI - 32.1, 15.2). Change in 8-iso-PGF2α did not correlate with change in telomere length (r = 0.07; 95% CI - 0.07, 0.20).

CONCLUSION

In breast cancer survivors, diet alone or exercise plus diet were associated with reduced oxidative stress but did not change telomere length. This analysis may inform future trials that aim to optimize healthy aging in cancer survivors.

Salivary telomere length and the risks of prediabetes and diabetes among middle-aged and older adults: findings from the Health and Retirement Study

AIM

To assess the association of telomere length (TL) with prediabetes/diabetes and to explore the potential factors affecting TL among individuals with prediabetes/diabetes by weight status.

METHODS

This study included 3,379 eligible adults (aged 45-85 years, males: 42%) from the US Health and Retirement Study in 2008. TL was assayed using quantitative PCR of saliva (T/S ratio). Linear and nonlinear associations between TL and prediabetes/diabetes were assessed using the logistic regression and restricted cubic spline model, respectively, adjusting for TL-plate numbers, age, sex, race, body mass index, lifestyles, diabetes medications, and cardiometabolic parameters (blood pressure, C-reactive protein, and total cholesterol). Multiple linear regression was used for testing any factors associated with TL.

RESULTS

Among 3,379 participants, 868 (25.7%) had prediabetes with a mean TL of 1.34 ± 0.37 (T/S ratio) and 858 (25.4%) had diabetes with a mean TL of 1.36 ± 0.43 (T/S ratio). Neither linear nor nonlinear association of TL with prediabetes/diabetes was significant by weight status. Age was negatively associated with TL in both normal-weight (β = - 0.002, p = 0.025) and overweight/obese (β = - 0.002, p = 0.006) prediabetes, but non-significant in normal-weight and overweight/obese diabetes. BMI and cardiometabolic parameters were not associated with TL in prediabetes/diabetes by weight status.

CONCLUSIONS

Salivary TL was not associated with prediabetes/diabetes among the US middle-aged and older adults. Further longitudinal studies are required to establish the link between TL and diabetes development and to identify potential factors affecting TL shortening, particularly in normal-weight diabetic patients.

Telomere length dynamics measured by flow-FISH in patients with obesity undergoing bariatric surgery

Obesity has negative effects on comorbidities, health-related quality of life and survival. Telomere length (TL) changes after bariatric surgery have been reported, but the studies are contradictory, and analyses using state-of-the art techniques for TL measurement, such as flow-FISH, are sparse. We measured TL dynamics via flow-FISH in patients undergoing bariatric surgery and compared their TL with 105 healthy individuals. Patients with obesity who underwent bariatric surgery were included. Lymphocyte and granulocyte absolute and age-adjusted (aa) TL were analyzed by flow-FISH before (preoperative cohort, n = 45) and after surgery (follow-up cohort, n = 35) at month 5.5 ± 3.9 (mean ± standard deviation [SD]). The initial lymphocyte aaTL was significantly shorter (-0.37 kb ± 0.18 kb, P = 0.045) in patients with obesity, while the granulocyte aaTL was not different from that in the healthy comparison population (0.28 kb ± 0.17 kb, P = 0.11). The telomere dynamics after surgery showed an increase in mean TL in both lymphocytes and granulocytes of patients with a pronounced BMI loss of ≥ 10 kg/m². We did not find any association between TL increase after surgery and age, sex or the type of procedure selected for bariatric surgery. We confirmed that patients suffering from obesity have significantly shorter lymphocyte TL using flow-FISH. Along with and dependent on the degree of weight reduction after bariatric surgery, TL significantly increased in both lymphocytes and granulocytes after a mean of 5.5 months. Our results show that bariatric surgery affects not only body weight but also biomarkers of aging, such as TL.

Drastic transformation of visceral adipose tissue and peripheral CD4 T cells in obesity

Obesity has a pronounced effect on the immune response in systemic organs that results in not only insulin resistance but also altered immune responses to infectious diseases and malignant tumors. Obesity-associated microenvironmental changes alter transcriptional expression and metabolism in T cells, leading to alterations in T-cell differentiation, proliferation, function, and survival. Adipokines, cytokines, and lipids derived from obese visceral adipose tissue (VAT) may also contribute to the systemic T-cell phenotype, resulting in obesity-specific pathogenesis. VAT T cells, which have multiple roles in regulating homeostasis and energy utilization and defending against pathogens, are most susceptible to obesity. In particular, many studies have shown that CD4 T cells are deeply involved in the homeostasis of VAT endocrine and metabolic functions and in obesity-related chronic inflammation. In obesity, macrophages and adipocytes in VAT function as antigen-presenting cells and contribute to the obesity-specific CD4 T-cell response by inducing CD4 T-cell proliferation and differentiation into inflammatory effectors via interactions between major histocompatibility complex class II and T-cell receptors. When obesity persists, prolonged stimulation by leptin and circulating free fatty acids, repetitive antigen stimulation, activating stress responses, and hypoxia induce exhaustion of CD4 T cells in VAT. T-cell exhaustion is characterized by restricted effector function, persistent expression of inhibitory receptors, and a transcriptional state distinct from functional effector and memory T cells. Moreover, obesity causes thymic regression, which may result in homeostatic proliferation of obesity-specific T-cell subsets due to changes in T-cell metabolism and gene expression in VAT. In addition to causing T-cell exhaustion, obesity also accelerates cellular senescence of CD4 T cells. Senescent CD4 T cells secrete osteopontin, which causes further VAT inflammation. The obesity-associated transformation of CD4 T cells remains a negative legacy even after weight loss, causing treatment resistance of obesity-related conditions. This review discusses the marked transformation of CD4 T cells in VAT and systemic organs as a consequence of obesity-related microenvironmental changes.

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

Background

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

Materials and Methods

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

Results

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

Conclusion

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

Editorial: Obesity and Accelerated Aging

Through shared pathophysiologic mechanisms, obesity exacerbates the age-related decline in physical function, which leads to frailty and disability. Obesity and aging are characterized by chronic low-grade inflammation, which contributes to reduced muscle quality and protein control mechanisms as well as to diminished muscle anabolic response. Obesity causes oxidative stress and inflammation, which increases telomere shortening. Calorie excess increases ROS formation, which damages nucleus, endoplasmic reticulum, and mitochondria and promotes cellular senescence. Given the persistence of DNA damage associated with altered DNA repair proteins in obesity and aging, it is thought that inability to repair DNA may be the principal molecular event that underlies accelerated aging. Calorie restriction in combination with exercise slows biological aging by protecting against the molecular and cellular damages that occur in obesity and aging. Promising approaches such as Time Restricted Eating, Mediterranean Diet, and Senolytics need further investigation.

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

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

Immune response to arbovirus infection in obesity

Obesity is a global health problem that affects 650 million people worldwide and leads to diverse changes in host immunity. Individuals with obesity experience an increase in the size and the number of adipocytes, which function as an endocrine organ and release various adipocytokines such as leptin and adiponectin that exert wide ranging effects on other cells. In individuals with obesity, macrophages account for up to 40% of adipose tissue (AT) cells, three times more than in adipose tissue (10%) of healthy weight individuals and secrete several cytokines and chemokines such as interleukin (IL)-1β, chemokine C-C ligand (CCL)-2, IL-6, CCL5, and tumor necrosis factor (TNF)-α, leading to the development of inflammation. Overall, obesity-derived cytokines strongly affect immune responses and make patients with obesity more prone to severe symptoms than patients with a healthy weight. Several epidemiological studies reported a strong association between obesity and severe arthropod-borne virus (arbovirus) infections such as dengue virus (DENV), chikungunya virus (CHIKV), West Nile virus (WNV), and Sindbis virus (SINV). Recently, experimental investigations found that DENV, WNV, CHIKV and Mayaro virus (MAYV) infections cause worsened disease outcomes in infected diet induced obese (DIO) mice groups compared to infected healthy-weight animals. The mechanisms leading to higher susceptibility to severe infections in individuals with obesity remain unknown, though a better understanding of the causes will help scientists and clinicians develop host directed therapies to treat severe disease. In this review article, we summarize the effects of obesity on the host immune response in the context of arboviral infections. We have outlined that obesity makes the host more susceptible to infectious agents, likely by disrupting the functions of innate and adaptive immune cells. We have also discussed the immune response of DIO mouse models against some important arboviruses such as CHIKV, MAYV, DENV, and WNV. We can speculate that obesity-induced disruption of innate and adaptive immune cell function in arboviral infections ultimately affects the course of arboviral disease. Therefore, further studies are needed to explore the cellular and molecular aspects of immunity that are compromised in obesity during arboviral infections or vaccination, which will be helpful in developing specific therapeutic/prophylactic interventions to prevent immunopathology and disease progression in individuals with obesity.

Telomere Length and Mitochondrial DNA Copy Number Variations in Patients with Obesity: Effect of Diet-Induced Weight Loss-A Pilot Study

Background: Telomere length (TL) and mitochondrial DNA (mtDNA) copy number shifts are linked to metabolic abnormalities, and possible modifications by diet-induced weight loss are poorly explored. We investigated the variations before (T0) and after a 1-year (T12) lifestyle intervention (diet + physical activity) in a group of outpatients with obesity. Methods: Patients aged 25−70 years with BMI ≥ 30 kg/m2 were enrolled. Clinical and biochemical assessments (including a blood sample for TL, mtDNA copy number and total antioxidant capacity, and TAC determinations) were performed at T0 and T12. Results: The change in TL and the mtDNA copy number was heterogeneous and not significantly different at T12. Patients were then divided by baseline TL values into lower than median TL (L-TL) and higher than median TL (H-TL) groups. The two groups did not differ at baseline for anthropometric, clinical, and laboratory characteristics. At T12, the L-TL group when compared to H-TL showed TL elongation (respectively, +0.57 ± 1.23 vs. −2.15 ± 1.13 kbp, p = 0.04), higher mtDNA copy number (+111.5 ± 478.5 vs. −2314.8 ± 724.2, respectively, p < 0.001), greater weight loss (−8.1 ± 2.7 vs. −6.1 ± 4.6 Kg, respectively, p = 0.03), fat mass reduction (−1.42 ± 1.3 vs. −1.22 ± 1.5%, respectively, p = 0.04), and increased fat-free mass (+57.8 ± 6.5 vs. +54.9 ± 5.3%, respectively, p = 0.04) and TAC levels (+58.5 ± 18.6 vs. +36.4 ± 24.1 µM/L, respectively, p = 0.04). Conclusions: TL and the mtDNA copy number significantly increased in patients with obesity and with lower baseline TL values after a 1-year lifestyle intervention. Larger longitudinal studies are needed to confirm the results of this pilot study.

A multi-exposure approach to study telomere dynamics in childhood: A role for residential green space and waist circumference

BACKGROUND

Telomeres are vulnerable to various environmental exposures and lifestyle factors, encompassed in the exposome. Recent research shows that telomere length is substantially determined early in life and that exposures in childhood may have important consequences in setting later life telomere length.

OBJECTIVES

We explore in a child population the associations of 17 exposures with telomere length and longitudinal telomere change.

METHODS

Children (2.8-10.3y at baseline, 51.3% boys) were followed-up for five to seven years. Relative telomere length was measured at baseline and follow-up using quantitative real-time PCR. Exposures and lifestyle factors included: body composition (body mass index and waist circumference), dietary habits (sugar- and fat-rich food intake, vegetables and fruit intake), psychosocial stress (events, emotions, behaviour), sleep duration, physical activity, and residential environmental quality (longterm black carbon, particulate matter exposure, and residential green space). Cross-sectional (n=182) and longitudinal (n=150) analyses were assessed using linear regression models, adjusting for age, sex, socioeconomic status and multiple testing.

RESULTS

Our longitudinal analyses showed that higher residential green space at baseline was associated with (β=0.261, p=0.002) lower telomere attrition and that children with a higher waist circumference at baseline showed a higher telomere attrition (β=-0.287, p=0.001). These two predictors were confirmed via LASSO variable selection and correction for multiple testing. In addition, children with more unhealthy exposures at baseline had a significantly higher telomere attrition over the follow-up period compared to children with more healthy exposures (β=-0.200, p=0.017).

DISCUSSION

Waist circumference and residential green space were identified as predictors associated with telomere attrition in childhood. These results further support the advantages of a healthy lifestyle from early age onwards and the importance of a green environment to promote molecular longevity from childhood onwards.

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

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

Genetic, Social, and Lifestyle Drivers of Healthy Aging and Longevity

Purpose of Review

"Healthy aging" is the state of the aging process in which a person can maintain physical, social, mental, and spiritual wellness. This literature review presents an overview of recent studies that explore how biological, social, and environmental factors contribute to healthy aging.

Recent Findings

A number of genome-wide association studies have been conducted recently for traits related to healthy aging, such as frailty index, healthspan, muscle strength, and parental longevity, leading to the discovery of dozens of genetic variants associated with these traits. In parallel, associations between healthy aging measures and multiple non-biological environmental elements have been identified as key moderators of the aging process, indirectly influencing day-to-day homeostatic processes.

Summary

Individual variations in lifespan and healthspan are influenced by genetic factors, with a heritability of ~ 25% in developed countries. Non-genetic risk variance is explained in part by social, cultural, and lifestyle conditions. Altogether, these factors contribute to a multifaceted state of wellness over time, shaping individual risk to frailty and resilience during the aging process. Notably, "Blue Zone" populations, which are characterized by an abundance in healthy lifestyles across generations, share some commonalities regarding determinants of health.

Mediation Effect of Platelet Traits on Associations of Central Obesity with Aging Biomarkers in Rural Adults of Henan, China

Background: To assess the associations of platelet traits and obesity indices with aging biomarkers (telomere length (TL) and mitochondrial DNA copy number (mtDNA-CN)). Methods: A cross-sectional study was performed among 5091 rural Chinese adults. Obesity indices (waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR)) and platelet traits (plateletcrit (PCT), platelet large cell ratio (P-LCR), mean platelet volume (MPV) and platelet distribution width (PDW)) were collected by physical examination. The aging biomarkers were determined by quantitative real-time polymerase chain reaction. Generalized linear regression models and mediation analysis were applied to explore the relationships between platelet traits, obesity indices, and aging biomarkers. Results: The mean age of the participants was 56 years (range: 18–79). Each one-unit increment in WC, WHR and WHtR were related to a 0.316 (95% confidence interval (CI): −0.437, −0.196), 0.323 (95% CI: −0.513, −0.134) and 0.277 (95% CI: −0.400, −0.153) decrease in relative TL; or a 0.102 (95% CI: −0.197, −0.007), 0.109 (95% CI: −0.258, −0.041) and 0.101 (95% CI: −0.199, −0.004) decrease in relative mtDNA-CN. The proportions of obesity indices with aging biomarkers mediated by platelet indices ranged from 2.85% to 10.10%. Conclusions: Increased central obesity indices in relation to shortened relative TL or decreased mtDNA-CN were mediated by platelet traits, indicating that obesity in association with the accelerated aging process may be partially attributable to abnormal platelet activity.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nutrient intakes and telomere length of cell-free circulating DNA from amniotic fluid: findings from the Mamma & Bambino cohort

Pregnancy represents a crucial period in which several exposures—and especially maternal diet—might shape children’s health. Thus, identifying how maternal dietary intakes early affect biological aging in children represents a public health mission. We aimed to assess the relationship between maternal intake of nutrients in early pregnancy and telomere length of cell-free circulating DNA (cfDNA) from amniotic fluid. We used data and samples from the ongoing prospective “Mamma & Bambino” study, which recruits mother–child pairs from Catania at the first prenatal visit. Maternal nutrient intakes were assessed using a Food Frequency Questionnaire, while relative telomere length of cfDNA was assessed by real-time polymerase chain reaction. Our analysis included 174 mother–child pairs. The intakes of iron, vitamin B1, and magnesium were positively correlated with relative telomere length (p-values < 0.05). However, only the intake of magnesium was positively associated with relative telomere length, after applying a linear regression model (β = 0.002; SE = 0.001; p = 0.024). Magnesium deficiency was negatively associated with relative telomere length after adjusting for the same covariates (β = −0.467; SE = 0.176; p = 0.009). To our knowledge, this is the first evidence of a positive relationship between maternal nutrient intake and telomere length of cfDNA. Further efforts are needed for deeply investigating the effect of maternal dietary intakes on telomere length, in order to develop effective public health strategies.

Shortening of leucocyte telomere length is independently correlated with high body mass index and subcutaneous obesity (predominantly truncal), in Asian Indian women with abnormal fasting glycemia

INTRODUCTION

Leucocyte telomere length (LTL) is linked to accelerate aging and premature mortality. In this research, we aimed to explore the relations between biochemical and anthropometry markers and LTL in Asian Indian women with abnormal fasting glycemia (impaired fasting glucose).

RESEARCH DESIGN AND METHODS

In this study, 797 pre-diabetic women (obese, 492; non-obese, 305) were recruited. Demographic and clinical profiles, anthropometry, and fasting blood glucose were evaluated. LTL was quantified by a quantitative PCR. LTL was expressed as the relative telomere length or telomere repeat:single copy gene (T:S) ratio. The subjects were separated into quartiles according to the LTL.

RESULTS

The average LTL was significantly decreased with increasing age. The average LTL was significantly shorter in obese women with abnormal fasting glycemia (p<0.05). R-squared (R²) statistic for multivariable linear model after adjusted for age, family income, education and hypertension showed that LTL was inversely correlated with body mass index (BMI), waist and hip circumference, waist-hip and waist-to-height ratio, truncal skinfolds (subscapular, and subscapular/triceps ratio, central and total skinfolds), fat mass (kg) and % body fat. The relationship between obesity measures and LTL (using the LTL quartile 1 as reference) identified central skinfolds (R²=0.92, p<0.0001), Σ4SF (R²=0.90, p<0.0001), BMI (R²=0.93, p<0.0001) and % body fat (R²=0.91, p<0.0001) as independent predictors of LTL.

CONCLUSIONS

Besides age, obesity and subcutaneous adiposity (predominantly truncal) are major contributors to telomere shortening in Asian Indian women with abnormal fasting glycemia (impaired fasting glucose).

Influences of Long-Term Exercise and High-Fat Diet on Age-Related Telomere Shortening in Rats

(1) Obesity and exercise are believed to modify age-related telomere shortening by regulating telomerase and shelterins. Existing studies are inconsistent and limited to peripheral blood mononuclear cells (PBMCs) and selected solid tissues. (2) Female Sprague Dawley (SD) rats received either standard diet (ND) or high-fat diet (HFD). For 10 months, half of the animals from both diet groups performed 30 min running at 30 cm/s on five consecutive days followed by two days of rest (exeND, exeHFD). The remaining animals served as sedentary controls (coND, coHFD). Relative telomere length (RTL) and mRNA expression of telomerase (TERT) and the shelterins TERF-1 and TERF-2 were mapped in PBMCs and nine solid tissues. (3) At study end, coND and coHFD animals showed comparable RTL in most tissues with no systematic differences in TERT, TERF-1 and TERF-2 expression. Only visceral fat of coHFD animals showed reduced RTL and lower expression of TERT, TERF-1 and TERF-2. Exercise had heterogeneous effects on RTL in exeND and exeHFD animals with longer telomeres in aorta and large intestine, but shorter telomeres in PBMCs and liver. Telomere-regulating genes showed inconsistent expression patterns. (4) In conclusion, regular exercise or HFD cannot systematically modify RTL by regulating the expression of telomerase and shelterins.

Insulin Resistance and Biological Aging: The Role of Body Mass, Waist Circumference, and Inflammation

The purpose of this investigation was to evaluate the association between insulin resistance and biological aging in a randomly selected sample of 2,596 U.S. women and men. Another key objective was to examine the extent to which the insulin resistance and biological aging association was influenced by differences in body mass, waist circumference, and systemic inflammation. Biological aging was indexed using the length of leukocyte telomeres. The homeostatic model assessment (HOMA) was employed to index insulin resistance. The body mass index (BMI) was used to represent body mass independent of height. Waist circumference was used to assess abdominal adiposity, and C-reactive protein (CRP) was measured to index body-wide inflammation. Insulin resistance and telomere length were both treated as continuous variables. Results revealed that insulin resistance was related significantly with cellular aging, after adjusting for several demographic covariates ( $F=5.7$ , $P=0.0234$ ). The association remained significant after controlling for multiple demographic and lifestyle covariates together ( $F=4.6$ , $P=0.0410$ ). However, after controlling for BMI, along with the other covariates, insulin resistance was no longer associated with biological aging $\left(F=2.1,P=0.1573\right)$ . After adjusting for differences in waist circumference, along with the demographic and lifestyle covariates, but not BMI, the relationship between insulin resistance and biological aging was negated further $\left(F=1.5,P=0.2283\right)$ . Adjusting for CRP with the demographic and lifestyle covariates, but not BMI or waist circumference, weakened the relationship ( $F=4.0$ , $P=0.0552$ ). Evidently, if all adults in the U.S. had the same BMI or waist circumference, there would not be a relationship between insulin resistance and telomere length. It appears that insulin resistance accounts for differences in biological aging mainly because of differences in BMI and waist circumference, especially the latter.

Telomere length and vitamin B12

Telomeres are non-coding nucleoprotein structures consisting of a highly conserved tandem repeat DNA sequence that caps the ends of chromosomes in eukaryotes. Telomeres confer chromosomal stability, protect the genome from nucleolytic degradation, avoid aberrant recombination and improper repair, and prevent random fusion of chromosomes. The end-replication problem results in telomere shortening with every cell division, eventually leading to cellular senescence and aging. Telomere length (TL) is thereby an ideal candidate for "biological aging." Telomeres possess guanine-rich repeats, which are highly susceptible to oxidative stress. Epidemiological studies have indicated the association of telomere attrition with mortality and various age-related diseases. Micronutrients comprising vitamins and minerals act as potential modulators of stress and can influence TL. Research has indicated that vitamin B12 (B12) regulates oxidative stress and maintains genomic stability, thereby influencing telomere integrity and cellular aging. The deficiency of B12 leads to elevated levels of homocysteine, which reduces the methylation potential and increases oxidative stress, thereby compromising the TL. Telomere shortening and mitochondrial dysfunction are independently linked to aging. However, they are connected through telomerase reverse transcriptase activity, which regulates mitochondrial biogenesis. Further, experimental evidence indicated the positive association of B12 with relative TL and mitochondrial DNA copy number, an indirect index of mitochondrial biogenesis. The present chapter provides some insights into the role of B12 in influencing TL. Exploring their association might open new avenues to understand the pathophysiology of aging and age-related diseases.

Effects of dietary interventions on telomere dynamics

Telomeres play a critical role in maintaining cellular fate through tight regulation of cell division and DNA damage or repair. Over the years, it is established that biological ageing is defined by a gradual derangement in functionality, productivity, and robustness of biological processes. The link between telomeres and ageing is highlighted when derangement in telomere biology often leads to premature ageing and concomitant accompaniment of numerous age-associated diseases. Unfortunately, given that ageing is a biologically complicated intricacy, measures to reduce morbidity and improve longevity are still largely in the infancy stage. Recently, it was discovered that dietary habits and interventions might play a role in promoting successful healthy ageing. The intricate relationship between dietary components and its potential to protect the integrity of telomeres may provide unprecedented health benefits and protection against age-related pathologies. However, more focused prospective and follow-up studies with and without interventions are needed to unequivocally link dietary interventions with telomere maintenance in humans. This review aims to summarise recent findings that investigate the roles of nutrition on telomere biology and provide enough evidence for further studies to consider the topic of nutrigenomics and its contributions toward healthy ageing and concomitant strategy against age-associated diseases.

Association Between Riboflavin Intake and Telomere Length: A Cross-Sectional Study From National Health and Nutrition Examination Survey 1999–2002

Background

Dietary habits and dietary intake affect telomere length, a reliable marker of biological aging and a predictor of chronic disease. Riboflavin (RF) is known as a water-soluble antioxidant vitamin, but its role in telomere length maintenance has yet to be elucidated.

Objective

The purpose of this study was to examine the relationship between dietary RF intake and telomere length in a nationally representative sample of adults.

Methods

Using the NHANES (1999–2002), telomere data of 4,298 participants aged ≥45 years were analyzed in a cross-sectional manner. Leukocyte telomere length was measured using the quantitative real-time polymerase chain reaction (qPCR). Dietary RF intake was assessed by a trained interviewer using 24-h dietary recall method. Generalized linear regressions were performed to evaluate the association between dietary RF intake and telomere length. Subgroup analyses were performed to further explore this relationship in sex and body mass index (BMI) subgroups.

Results

Among the 3,788 participants included, the average telomere length was longer in females (P = 0.014), while they had a lower average RF intake compared to males (P < 0.001). There was a weak positive correlation between RF intake and telomere length both when unadjusted (β = 0.011; P = 0.037) and adjusted for age, sex, and ethnicity (β = 0.013; P = 0.033). Subgroup analyses showed a positive association between RF intake and the telomere length in female after adjusting for confounding factors (β = 0.029; P = 0.046). In the female subgroup, there were significant positive relationships between telomere length and RF intake in the obese group (β = 0.086, P = 0.022).

Conclusion

Increased dietary RF intake was significantly associated with longer telomere length in middle-aged and older American females, especially in low RF intake obese female.

Association between Telomere Length and Pediatric Obesity: A Systematic Review

Objective: Telomere length (TL) is a robust marker of biological aging, and increased telomere attrition is noted in adults with obesity. The primary objective of this systematic review was to summarize current knowledge on the effects of childhood obesity in TL. The secondary objective was to assess the effect of weight management interventions in TL. Methods: The following databases were searched: PubMed, Scopus, Web of Science and Heal-link.gr from inception to September 2021. The search was performed using the following combinations of terms: “telomer*” [All Fields] AND (“length” [All Fields] OR “lengths” [All Fields]) AND “obes*” [All Fields] AND (“child*” [All Fields] OR “adolescen*” [All Fields]). Results: A total of 16 original articles were included in this systematic review. Eleven of them were cross-sectional and five were lifestyle interventions. Conclusions: There was a tendency towards a negative association between childhood obesity and TL. Life-style interventions in children have been associated with increased TL peripherally, indicating a possible association of the redistribution of younger cells in the periphery with the favorable effect of these interventions. Further prospective studies with larger sample sizes that employ other markers of cell aging would potentially elucidate this important mechanistic relation.

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.

Profiling the Skeletal Muscle Proteome in Patients on Atypical Antipsychotics and Mood Stabilizers

Atypical antipsychotics (AAP) are used in the treatment of severe mental illness. They are associated with several metabolic side effects including insulin resistance. The skeletal muscle is the primary tissue responsible for insulin-stimulated glucose uptake. Dysfunction of protein regulation within the skeletal muscle following treatment with AAPs may play a role in the associated metabolic side effects. The objective of this study was to measure protein abundance in the skeletal muscle of patients on long-term AAP or mood stabilizer treatment. Cross-sectional muscle biopsies were obtained from patients with bipolar disorder and global protein abundance was measured using stable isotope labeling by amino acid (SILAC) combined with high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Sixteen patients completed muscle biopsies and were included in the proteomic analyses. A total of 40 proteins were significantly different between the AAP group and the mood stabilizer group. In-silico pathway analysis identified significant enrichment in several pathways including glucose metabolism, cell cycle, apoptosis, and folate metabolism. Proteome abundance changes also differed based on protein biological processes and function. In summary, significant differences in proteomic profiles were identified in the skeletal muscle between patients on AAPs and mood stabilizers. Future work is needed to validate these findings in prospectively sampled populations.

Association between the Oxidative Balance Score and Telomere Length from the National Health and Nutrition Examination Survey 1999-2002

Purpose. Leukocyte telomere length (LTL) is an important biomarker of aging. The oxidative balance score (OBS) is used to assess the oxidative stress-related exposures of diet and lifestyle. This study is aimed at exploring if the OBS was associated with LTL. Methods. 3220 adults were included in this study from the National Health and Nutrition Examination Survey (NHANES) 1999-2002. LTL was assayed from leukocyte DNA. Twenty dietary and lifestyle factors were selected to score the OBS. Survey-based multivariable linear regression was conducted to assess the association between the OBS and log-transformed LTL. Results. The association between the OBS and log-transformed LTL was positive in females but not males. For females, compared with the lowest OBS category as a reference, the multivariable-adjusted beta estimate (95% confidence interval, CI) for the highest OBS category was 0.0701 (0.0205–0.1197) ( $p$ for $\text{trend}<0.01$ ), and the multivariable-adjusted beta estimate (95% CI) of the continuous OBS was 0.0039 (0.0014–0.0065). There was also the gender difference in the correlations of the dietary OBS and the lifestyle OBS with log-transformed LTL. Conclusion. There was a positive association between the OBS and LTL in females. This result suggested that diet and lifestyle might affect LTL by regulating oxidative balance.

Associations of leucocyte telomere length with cardio-metabolic risk profile in a South African HIV-infected population

Leukocyte Telomere length (LTL) is an independent predictor of cardio-metabolic diseases (CMDs) and Human Immuno Virus (HIV) infection. However, studies are lacking on the association between LTL with CMD profile in people with HIV. Accordingly, we investigated the association between LTL and CMD profile in HIV-infected adult South Africans.This cross-sectional study included 728 HIV patients (20.6% men; median age 38 years) recruited across 17 public healthcare facilities in Cape Town. CMD markers were compared across quartiles of LTL, and spearman correlations assessed the continuous association of LTL with CMD markers. Linear and logistic regressions were then used to relate LTL with CMD risk profile, with appropriate adjustment for confounders.The prevalence of obesity, hypertension and diabetes were 34.8%, 36.8%, and 8.4%, respectively. In age, sex and body mass index adjusted models, increasing Log10LTL was associated with decreasing systolic (β = -10.52) and diastolic (β = -6.74) blood pressures, HOMA-β (β = -70.72), increasing total cholesterol (β = 0.544), non-high-density lipoprotein cholesterol (β = 0.472), and waist-to-height-ratio > 0.5 (odds ratio [OR] = 5.67), all P < .05. Compared to those in the bottom quarter, those in the top LTL quarter had lower prevalence of hypertension (OR = 0.65), and higher prevalence of total cholesterol > 5 mmol/L (OR = 1.94), and low-density lipoprotein-cholesterol > 3 mmol/L (OR = 1.62), all P < .05. LTL was not associated with diabetes nor general obesity. It was associated with Alanine Transaminase (ALT) and heart rate in univariable analyses.LTL shortening was associated with some CMD risk factors in HIV-infected adults on anti-retroviral therapy in South Africa. Prospective research is needed to explore the direction and implications of these associations.

Intermediate Effects of Body Mass Index and C-Reactive Protein on the Serum Cotinine- Leukocyte Telomere Length Association

We aimed to examine the association between serum cotinine and leukocyte telomere length (LTL) and the intermediate effects of body mass index (BMI) and C-reactive protein (CRP) on modulating the association. This study included 4,047 adults from the 1999 to 2002 National Health and Nutrition Examination Survey. In the combined sample, after adjusting for age, race, sex, physical activity, and alcohol use, the total effect of serum cotinine on LTL was significant (standardized regression coefficient, β = −0.049, p = 0.001) without BMI and CRP included in the model. With inclusion of BMI but without CRP in the model, the direct effect of cotinine on LTL in its absolute value increased to β = −0.053 (p < 0.001), and the suppression effect of BMI was estimated at 8.8%. With inclusion of CRP but without BMI in the model, the direct effect of cotinine on LTL in its absolute value decreased to β = −0.040 (p = 0.008), and the mediation effect of CRP was estimated at 16.9%. With inclusion of both BMI and CRP in the model, BMI and CRP still had significant suppression and mediation effects, respectively, on the cotinine-LTL association. These findings suggest that weight and inflammation have different roles in the inverse association between serum cotinine and LTL.

Inflammation as A Precursor of Atherothrombosis, Diabetes and Early Vascular Aging

Vascular disease was for a long time considered a disease of the old age, but it is becoming increasingly clear that a cumulus of factors can cause early vascular aging (EVA). Inflammation plays a key role in vascular stiffening and also in other pathologies that induce vascular damage. There is a known and confirmed connection between inflammation and atherosclerosis. However, it has taken a long time to prove the beneficial effects of anti-inflammatory drugs on cardiovascular events. Diabetes can be both a product of inflammation and a cofactor implicated in the progression of vascular disease. When diabetes and inflammation are accompanied by obesity, this ominous trifecta leads to an increased incidence of atherothrombotic events. Research into earlier stages of vascular disease, and documentation of vulnerability to premature vascular disease, might be the key to success in preventing clinical events. Modulation of inflammation, combined with strict control of classical cardiovascular risk factors, seems to be the winning recipe. Identification of population subsets with a successful vascular aging (supernormal vascular aging-SUPERNOVA) pattern could also bring forth novel therapeutic interventions.

The Relationship between Telomere Length and Gestational Weight Gain: Findings from the Mamma & Bambino Cohort

Inadequate gestational weight gain (GWG) affects a growing number of pregnancies, influencing intrauterine environment and long-term health. Uncovering molecular mechanisms associated with GWG could be helpful to develop public health strategies for tackling this issue. Here, our study aimed to understand the relationship of DNA telomere length with weigh gain during pregnancy, using data and samples from the ongoing prospective “Mamma & Bambino” study (Catania, Italy). GWG was calculated according to the Institute of Medicine (IOM) guidelines. Relative telomere length was assessed by real-time quantitative polymerase chain reaction in 252 samples of maternal leucocyte DNA (mlDNA) and 150 samples of cell-free DNA (cfDNA) from amniotic fluid. We observed that relative telomere length of mlDNA seemed to weakly increase with GWG. In contrast, telomere length of cfDNA exhibited a U-shaped relationship with GWG. Women with adequate GWG showed longer telomere length than those who gained weight inadequately. Accordingly, the logistic regression model confirmed the association between telomere length of cfDNA and adequate GWG, after adjusting for potential confounders. Our findings suggest an early effect of GWG on telomere length of cfDNA, which could represent a molecular mechanism underpinning the effects of maternal behaviours on foetal well-being.

Shorter telomeres among individuals with physical disability: The moderating role of perceived stress

OBJECTIVES

Evidence suggests that individuals with physical disability may suffer from psychological distress and accelerated cellular aging, manifested by shortened telomere length (TL), compared with healthy individuals. Studies indicate that high levels of perceived stress and depression may increase the physiological susceptibility and thus, may contribute to a short TL. However, the moderating role of perceived stress and depression within the relationship between physical disability and TL remains unknown.

METHODS

The participants consisted of 119 male subjects (mean age 54.36 years, range 35-70). Of them, 30 were able-bodied and 86 had a physical disability: 34 were due to Poliomyelitis (polio) and 55 were due to spinal cord injury (SCI). Blood samples for TL analysis were collected; the participants completed questionnaires and underwent disability evaluation.

RESULTS

Participants with disability had a shorter TL as well as elevated levels of perceived stress and depression compared with able-bodied controls. Both the perceived stress and depression were correlated with a shorter TL. Nonetheless, perceived stress, rather than depression, moderated the relationship between disability and TL; among participants with higher perceived stress levels, in particular, individuals with physical disability had a shorter TL than the able-bodied controls.

DISCUSSION

The present findings suggest that individuals with physical disability and who exhibit high levels of perceived stress may be particularly vulnerable for accelerated cellular aging, suggesting that perceived stress can be used as a valuable target for intervention.

Association Between Body Weight and Telomere Length Is Predominantly Mediated Through C-Reactive Protein

CONTEXT

Both obesity and inflammation are related to accelerated aging. It is not yet known whether inflammation mediates the effects of obesity on aging.

OBJECTIVE

This work aims to dissect the direct effect of body mass index (BMI) and its indirect effect through C-reactive protein (CRP) on leukocyte telomere length (LTL) to determine the mediation effect of CRP on the BMI-LTL association.

METHODS

The study cohort included 5451 adults (1404 Mexican American, 3114 White, and 933 Black individuals; 53.5% male; mean age = 49.2 years) from the 1999 to 2002 National Health and Nutrition Examination Survey. General mediation models were used to examine the mediation effect of CRP on the BMI-LTL association.

RESULTS

After adjusting for age, race, sex, physical activity, alcohol use, and serum cotinine, the total effect of BMI on LTL was significant (standardized regression coefficient, β = -.054, P < .001) without CRP included in the model. With inclusion of CRP in the model, the indirect effect of BMI on LTL through CRP was estimated at β equal to -.023 (P < .001), and the direct effect of BMI on LTL in its absolute value decreased to β equal to -.031 (P = .025). The mediation effect of CRP was estimated at 42.6%. The mediation model parameters did not differ significantly between race and sex groups.

CONCLUSION

These results suggest that the inverse BMI-LTL association is partly mediated by obesity-induced inflammation. The significant direct effect of BMI on LTL with removal of the mediation effect through CRP indicates that obesity is associated with LTL attrition also through other noninflammatory mechanisms.

Genetic, Environmental and Lifestyle Determinants of Accelerated Telomere Attrition as Contributors to Risk and Severity of Multiple Sclerosis

Telomeres are protective structures at the ends of linear chromosomes. Shortened telomere lengths (TL) are an indicator of premature biological aging and have been associated with a wide spectrum of disorders, including multiple sclerosis (MS). MS is a chronic inflammatory, demyelinating and neurodegenerative disease of the central nervous system. The exact cause of MS is still unclear. Here, we provide an overview of genetic, environmental and lifestyle factors that have been described to influence TL and to contribute to susceptibility to MS and possibly disease severity. We show that several early-life factors are linked to both reduced TL and higher risk of MS, e.g., adolescent obesity, lack of physical activity, smoking and vitamin D deficiency. This suggests that the mechanisms underlying the disease are connected to cellular aging and senescence promoted by increased inflammation and oxidative stress. Additional prospective research is needed to clearly define the extent to which lifestyle changes can slow down disease progression and prevent accelerated telomere loss in individual patients. It is also important to further elucidate the interactions between shared determinants of TL and MS. In future, cell type-specific studies and advanced TL measurement methods could help to better understand how telomeres may be causally involved in disease processes and to uncover novel opportunities for improved biomarkers and therapeutic interventions in MS.

Systematic review and meta-analysis of the association between paediatric obesity and telomere length

AIM

This systematic review and meta-analysis aimed to assess the association between paediatric obesity and telomere length.

METHODS

We conducted a comprehensive literature search for original studies assessing the associations between obesity and telomere length in children. Fixed or random effects with inverse-variance meta-analysis were used to estimate the standardised mean difference (SMD) and its 95% confidence interval (95% CI) between overweight or obese and normal-weight children. Heterogeneity was assessed using the I² statistic, and meta-regression analyses were used to evaluate the potential source of heterogeneity. Subgroup analysis was further conducted by sex.

RESULTS

A total of 11 studies were included. The meta-analysis showed that children who were overweight or obese had shorter telomere length than normal-weight children (SMD: -0.85; 95% CI: -1.42 to -0.28; p < 0.01). However, significant heterogeneity was present (I²  = 97%; p < 0.01). Study design, methods used for measuring telomere length, tissue types, mean age, and percentage of boys were not the source of heterogeneity revealed by meta-regression analysis. The inverse trend was significant only in boys, but not in girls.

CONCLUSION

There was a negative association between paediatric obesity and telomere length. Weight control in children might have beneficial effect on telomere length.