Telomere length and chronological age across the human lifespan: A systematic review and meta-analysis of 414 study samples including 743,019 individuals

Telomere length and telomerase activity in men and non-pregnant women with and without metabolic syndrome: a systematic review and bootstrapped meta-analysis

Purpose

We performed a systematic review and meta-analysis to examine the associations between telomere length and telomerase activity in subjects with and without metabolic syndrome (MetS).

Methods

The meta-analysis protocol was registered in the PROSPERO database. The PubMed, Embase, Cochrane Library, and LILACS databases were searched for studies reporting telomere length or telomerase activity in adult men and non-pregnant women with and without MetS. The risk of bias was assessed with the Newcastle-Ottawa Scale. Random effects and inverse variance methods were used to meta-analyze associations. We conducted a bootstrapped analysis to test the accuracy of clinical results.

Results

Five studies reported telomere length and two studies telomerase activity. There was no significant difference in telomere length (standardized mean difference [SMD]: 0.10, 95% confidence interval [CI]: -0.07, 0.28, I 2: 54%), between subjects of similar age (mean difference: 2.68, 95%CI: -0.04, 5.40 years) with and without the MetS. Subjects with MetS displayed significantly higher body mass index, triglycerides, and blood pressure, and lower HDL-cholesterol values than subjects without the syndrome. A bootstrapping mediation analysis of telomere length confirmed the clinical results. There was no significant difference in telomerase activity (SMD: 1.19, 95% CI -0.17, 2.55, I 2: 93%) between subjects with and without the MetS.

Conclusion

There were no significant differences of telomere length and telomerase activity in patients with MetS and subjects of similar age without the syndrome.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01513-4.

From geroscience to precision geromedicine: Understanding and managing aging

Major progress has been made in elucidating the molecular, cellular, and supracellular mechanisms underlying aging. This has spurred the birth of geroscience, which aims to identify actionable hallmarks of aging. Aging can be viewed as a process that is promoted by overactivation of gerogenes, i.e., genes and molecular pathways that favor biological aging, and alternatively slowed down by gerosuppressors, much as cancers are caused by the activation of oncogenes and prevented by tumor suppressors. Such gerogenes and gerosuppressors are often associated with age-related diseases in human population studies but also offer targets for modeling age-related diseases in animal models and treating or preventing such diseases in humans. Gerogenes and gerosuppressors interact with environmental, behavioral, and psychological risk factors to determine the heterogeneous trajectory of biological aging and disease manifestation. New molecular profiling technologies enable the characterization of gerogenic and gerosuppressive pathways, which serve as biomarkers of aging, hence inaugurating the era of precision geromedicine. It is anticipated that, pending results from randomized clinical trials and regulatory approval, gerotherapeutics will be tailored to each person based on their genetic profile, high-dimensional omics-based biomarkers of aging, clinical and digital biomarkers of aging, psychosocial profile, and past or present exposures.

Exploring the relationship between air pollution and telomere length: Baseline findings from a comprehensive ambispective cohort study

BACKGROUND

Telomere length is a biomarker of cellular aging, influenced by various environmental and lifestyle factors. Air pollution is a known environmental stressor that may impact telomere dynamics. This study aimed to investigate the effect of age, lifetime exposure to air pollution, inflammatory parameters and selected lifestyle factors on telomere length.

METHODS

The study included 356 participants aged 35-65 living in two regions with varying pollution. Telomere length was measured using qPCR. Individual lifetime exposures to PM10, PM2.5, NO2, benzo(a)pyrene and benzene were calculated based on historical air quality data. Statistical analysis of age, pollution exposure, inflammatory parameters, and lifestyle factors on telomere length was performed using logistic regression and generalized linear models, with odds ratios calculated.

RESULTS

Unexpectedly, higher air pollutants lifetime exposures were associated with longer telomeres, particularly for PM10 51-55 μg/m3 (OR = 5.67, p < 0.001), PM2.5 42-45 μg/m3 (OR = 6.56, p < 0.001), B(a)P 6.9-8.3 ng/m3 (OR = 5.25, p = 0.002), NO2 26-27 μg/m3 (OR = 5.22, p = 0.001) and benzene 2.45-2.75 μg/m3 (OR = 6.13, p < 0.001). Age significantly affected telomere length, with older individuals having shorter telomeres. Socioeconomic factors such as college education were positively associated with longer telomeres, while lifestyle factors did not show significant associations. IL-8 was identified as a significant inflammatory marker negatively associated with very long telomeres.

CONCLUSION

These baseline findings bring new perspective to the relationship between air pollution and telomere length. Contrary to traditional views, the results suggest potential adaptive responses, highlighting the need for further longitudinal research to explore telomere dynamics over time in conjunction with other factors.

Maternal telomere length and oxidative stress in pregnancy: cross-sectional analysis with an exploratory examination of systemic inflammation

BACKGROUND

Telomere length (TL) is a marker of cellular aging associated with risk for age-related diseases and is known to be influenced by various factors, including oxidative stress and inflammation, in the contexts of stress and aging. The physiological demands of pregnancy may impact maternal TL, though research in this area is sparse. We tested oxidative stress and explored inflammation as predictors of maternal TL in a sample of women with normative pregnancies.

METHODS

Participants (N = 88, aged 18 to 46 years, 25% non-Hispanic Black, 65% non-Hispanic White) were recruited during their 2nd or 3rd trimester. TL was measured using saliva via qPCR as absolute TL. Oxidative stress was derived from principal component analysis of selected metabolites measured via urinary metabolomics. Inflammation was quantified as total IL-6 in serum. Hypotheses were tested with stepwise generalized linear models.

RESULTS

Longer TL was predicted by higher oxidative stress (b = 0.20 ± 0.08; P =.019), controlling for maternal age, gestational age, race/ethnicity, maternal BMI, and income-to-needs ratio. In our exploratory analysis, longer TL was also predicted by higher IL-6 (b = 0.76 ± 0.20; P =.0003) controlling for covariates. There was no significant interaction between oxidative stress and inflammation predicting TL.

CONCLUSION

Our findings suggest that in normative pregnancies, both oxidative stress and inflammation are independently associated with longer telomere length. Given that these associations are inconsistent with the role of oxidative stress and inflammation on telomere biology in non-pregnant samples, future work should aim to replicate these findings in both normal and high-risk pregnancies, explore mechanisms underlying these associations using longitudinal designs, and examine how these relationships influence maternal and fetal health.

The relationship between physical activity and telomere length in women: A systematic review

Telomere length (TL) is a biomarker of cellular aging with variations observed by sex, age, race, and ethnicity. Prior studies have suggested that physical activity (PA) may positively impact TL by potentially elongating telomeres and slowing cellular aging. However, research examining the optimal type and intensity of PA needed to elicit these changes specific to women remains limited. This systematic review aimed to investigate variations in TL in response to PA among women, exploring how these effects differ by age, race, or ethnicity. Following PRISMA guidelines, searches across five databases identified 17 relevant studies published from 2008 to 2022. A narrative synthesis of study findings indicated PA did not have a significant relationship with TL in women. However, a possible positive relationship was noted between specific types of PA and TL, specific to combined aerobic and strength-training PA and high intensity interval training interventions. The impact of PA on TL appeared to be age-dependent as well, showing significant positive relationships between PA and TL in early and later adulthood but not in middle adulthood. Findings related to race or ethnicity were inconclusive due to limited analyses from the included studies. The studies varied greatly by PA type, intensity, duration, and frequency, which, along with the reliance on self-reported PA measures in the observational studies, impacted the ability to draw firm conclusions. This review underscores the necessity for future research in large cohort studies using objectively measured PA interventions to further clarify the complex associations between PA and TL in women.

Telomeres in skin aging

Skin aging is influenced by both intrinsic and extrinsic factors. The gradual manifestation of changes in telomere length and telomerase activity, as crucial indicators of aging, elucidates the underlying mechanism of skin aging. This review aims to comprehensively analyze the association between telomeres and aging, along with their impact on skin biological function. Firstly, we summarize the structure and function of telomeres and their role in cell division. Subsequently, we discuss the mechanisms through which telomere regulation contributes to aging processes while analyzing its involvement in skin aging by elaborating on biological markers. Furthermore, this paper presents a summary of recent research progress that reveals the correlation between telomere length and skin aging as well as model building methods; it also proposes telomere length as a potential indicator for predicting skin aging. Finally, anti-aging strategies based on telomere protection are discussed including drug therapy and lifestyle adjustments. This paper provides a systematic overview of the role played by telomeres in the field of skin aging for the first time, offering new perspectives and ideas for future prevention and treatment.

Navigating the maze of active ageing measurement: untangling methodological and theoretical issues in the UJACAS questionnaire

Active Ageing (AA) involves maintaining engagement in physical, social, and mental activities in older adulthood, reflecting societal values and political agendas. Despite various measurement tools, there is no universal standard. The University of Jyväskylä Active Ageing Scale (UJACAS) is increasingly used in Europe but faces inconsistencies from varying response scales across versions. This perspective paper examines these discrepancies and proposes a refined model for AA measurement, emphasizing the dimensions of motivation, ability, opportunity, and activity frequency. The goal is to improve the accuracy of AA assessments by adjusting for personal and environmental limitations, ensuring a fair evaluation that captures the complexities of ageing. The proposed adjustments to the UJACAS scoring model include recalibrating the equation to account for personal and environmental limitations, integrating motivation as a separate measure, and exploring adaptive methodologies to ensure fairer and more nuanced assessments of Active Ageing, particularly for individuals facing disabilities or obstacles. By addressing these issues, this perspective paper aims to enhance the effectiveness of AA tools for older adults. Moreover, adopting these methodological challenges has significant societal implications. Precise measurement of AA is essential for tailoring interventions to the needs of diverse older populations and for designing policies that promote inclusive, healthy and safe ageing. Enhancing the accuracy of AA assessments can inform strategies that empower older adults, mitigate disparities, and foster resilience in ageing communities. This study highlights the necessity of advancing AA measurement frameworks to support evidence-based decisions in public health and social policy.

Exploring DNA methylation, telomere length, mitochondrial DNA, and immune function in patients with Long-COVID

BACKGROUND

Long-COVID is defined as the persistency or development of new symptoms 3 months after the initial SARS-CoV-2 infection, with these symptoms lasting for at least 2 months with no other explanation. Common persistent symptoms are fatigue, sleep disturbances, post-exertional malaise (PEM), pain, and cognitive problems. Long-COVID is estimated to be present in about 65 million people. We aimed to explore clinical and biological factors that might contribute to Long-COVID.

METHODS

Prospective longitudinal cohort study including patients infected with SARS-CoV-2 between March 2020 and March 2022. Patients were assessed between 4 and 12 months after infection at the COVID follow-up clinic at UZ Leuven. We performed a comprehensive clinical assessment (including questionnaires and the 6-min walking test) and biological measures (global DNA methylation, telomere length, mitochondrial DNA copy number, inflammatory cytokines, and serological markers such as C-reactive protein, D-dimer, troponin T).

RESULTS

Of the 358 participants, 328 were hospitalised, of which 130 had severe symptoms requiring intensive care admission; 30 patients were ambulatory referrals. Based on their clinical presentation, we could identify 6 main clusters. One-hundred and twenty-seven patients (35.4%) belonged to at least one cluster. The bigger cluster included PEM, fatigue, sleep disturbances, and pain (n = 57). Troponin T and telomere shortening were the two main markers predicting Long-COVID and PEM-fatigue symptoms.

CONCLUSIONS

Long-COVID is not just one entity. Different clinical presentations can be identified. Cardiac involvement (as measured by troponin T levels) and telomere shortening might be a relevant risk factor for developing PEM-fatigue symptoms and deserve further exploring.

Bee Pollen Phytochemicals and Nutrients as Unequaled Pool of Epigenetic Regulators: Implications for Age-Related Diseases

Bee pollen is characterized by an exceptional diversity and abundance of micronutrients and bioactive phytochemicals. This richness remains very sparsely investigated, but accumulating evidence strongly supports a promising future for bee pollen in human nutrition and medicine. Epigenetic regulation is among the most compelling biomedical topics that remain completely untapped in bee pollen and bee derivative research. In our current research, we identified numerous ubiquitous compounds that are consistently present in this matrix, regardless of its botanical and geographical origins, and that have been well studied and documented as epigenetic regulators in recent years. Given the relative newness of both bee pollen biomedical research and epigenetic studies within nutritional, pharmaceutical, and medical sciences, this review aims to bridge these valuable fields and advance related experimental investigations. To the best of our knowledge, this is the first work that has aimed to comprehensively investigate the epigenetic modulatory potential of bee pollen compounds. Our findings have also unveiled several intriguing phenomena, such as a dual effect of the same compound depending on the cellular context or the effect of some compounds on the cross-generational heritability of epigenetic traits. Although experimental studies of epigenetic regulation by bee pollen as a whole or by its extract are still lacking, our current study clearly indicates that this research avenue is very promising and worth further investigations. We hope that our current work constitutes a foundational cornerstone of future investigations for this avenue of research.

Association between plant and animal protein and biological aging: findings from the UK Biobank

PURPOSE

This study aimed to evaluate the relationship between plant protein, animal protein and biological aging through different dimensions of biological aging indices. Then explore the effects of substitution of plant protein, animal protein, and their food sources on biological aging.

METHODS

The data came from 79,294 participants in the UK Biobank who completed at least two 24-h dietary assessments. Higher Klemera-Doubal Method Biological Age (HKDM-BA), higher PhenoAge (HPA), higher allostatic load (HAL), and longer telomere length (LTL) were estimated to assess biological aging. Logistic regression was used to estimate protein-biological aging associations. Substitution model was performed to assess the effect of dietary protein substitutions.

RESULTS

Plant protein intake was inversely associated with HKDM-BA, HPA, HAL, and positively associated with LTL (odds ratios after fully adjusting and comparing the highest to the lowest quartile: 0.83 (0.79-0.88) for HKDM-BA, 0.86 (0.72-0.94) for HPA, 0.90 (0.85-0.95) for HAL, 1.06 (1.01-1.12) for LTL), while animal protein was not correlated with the four indices. Substituting 5% of energy intake from animal protein with plant protein, replacing red meat or poultry with whole grains, and replacing red or processed meat with nuts, were negatively associated with HKDM-BA, HPA, HAL and positively associated with LTL. However, an inverse association was found when legumes were substituted for yogurt. Gamma glutamyltransferase, alanine aminotransferase, and aspartate aminotransferase mediated the relationship between plant protein and HKDM-BA, HPA, HAL, and LTL (mediation proportion 11.5-24.5%; 1.9-6.7%; 2.8-4.5%, respectively).

CONCLUSION

Higher plant protein intake is inversely associated with biological aging. Although there is no association with animal protein, food with animal proteins displayed a varied correlation.

An in-silico approach to the dynamics of proliferation potential in stem cells and the study of different therapies in cases of ovarian dysfunction

A discrete mathematical model based on ordinary differential equations and the associated continuous model formed by a partial differential equation, which simulate the generational and temporal evolution of a stem cell population, are proposed. The model parameters are the maximum proliferation potential and the rates of mitosis, death events and telomerase activity. The mean proliferation potential at each point in time is suggested as an indicator of population aging. The model is applied on hematopoietic stem cells (HSCs), with different telomerase activity rates, in a range of variation of maximum proliferation potential in healthy individuals, to study the temporal evolution of aging. HSCs express telomerase, however not at levels that are sufficient for maintaining constant telomere length with aging [1,2]. Women with primary ovarian insufficiency (POI) are known to have low telomerase activity in granulosa cells and peripheral blood mononuclear cells [3]. Extrapolating this to hematopoietic stem cells, the mathematical model shows the differences in proliferation potential of the cell populations when telomerase expression is activated using sexual steroids, though the endogenous promoter or with gene therapy using exogenous, stronger promoters within the adeno-associated virus. In the first case, proliferation potential of cells from POI condition increases, but when adeno-associated viruses are used, the proliferation potential reaches the levels of healthy cell populations.

Telomere length and chronotype among women in the California Teachers Study (CTS)

While links between certain chronotypes and poorer health outcomes have been well established in previous studies, few studies have examined the relationship between chronotype and cellular aging. Using data from the California Teachers Study (CTS), the present study evaluates the relationship between cellular aging and chronobiology through an analysis of leukocyte telomere length (LTL) and chronotype among 817 predominantly postmenopausal women with no history of cancer and occupations not associated with night-shift work. Unconditional logistic regression models were run to estimate odds ratios (ORs) for each chronotype category, adjusted for age, ethnicity, and smoking status. Analyses were then stratified by potential modifiers to assess whether results varied among specific subgroups within the sample. Women who reported being current evening types and evening types from teen years to now were significantly less likely to have short LTL compared to women who reported being current morning types or morning types from teen years to now (OR = 0.72; 95% CI = 0.53-0.98; OR = 0.57; 95% CI = 0.39-0.84). Our results suggest that women with no history of cancer who identify as evening chronotypes may undergo decreased cellular aging compared to women in the same population who identify as morning types. Further studies on populations of postmenopausal women are warranted.

High-throughput single telomere analysis using DNA microarray and fluorescent in situ hybridization

The human telomere system is highly dynamic. Both short and long leucocyte average telomere lengths (aTL) are associated with an increased risk of cancer and early death, illustrating the complex relationship between TL and human health and the importance of assessing TL distributions with single TL analysis. A DNA microarray and telomere fluorescent in situ hybridization (DNA-array-FISH) approach was developed to measure the base-pair (bp) lengths of single telomeres. On average 32000 telomeres were measured per DNA sample with one microarray chip assaying 96 test DNA samples. Various telomere parameters, i.e. aTL and the frequency of short/long telomeres, were computed to delineate TL distribution. The intra-assay and inter-assay coefficient of variations of aTL ranged from 1.37% to 3.98%. The correlation coefficient (r) of aTL in repeated measurements ranged from 0.91 to 1.00, demonstrating high measurement precision. aTLs measured by DNA-array-FISH predicted aTLs measured by terminal restriction fragment (TRF) analysis with r ranging 0.87-0.99. A new accurate and high-throughput method has been developed to measure the bp lengths of single telomeres. The large number of single TL data provides an opportunity for an in-depth analysis of telomere dynamics and the complex relationship between telomere and age-related diseases.

Partial Recovery of Telomere Length After Long-term Virologic Suppression in Persons With HIV-1

Background

People with HIV-1 (PWH) age differently than the general population. Blood telomere length (BTL) attrition is a surrogate biomarker of immunosenescence and aging in PWH. BTL is reduced immediately after HIV-1 infection and recovers in PWH with long-term virologic suppression, but the extent of this recovery is unknown.

Methods

This prospective 6-year observational study assessed the evolution of BTL in PWH who were virologically suppressed. A cross-sectional analysis additionally compared BTL with age- and sex-matched blood donors and sex-matched persons older than 60 years from a general population cohort. DNA from whole blood was isolated, and relative BTL was determined by monochrome quantitative multiplex polymerase chain reaction assay and expressed as the ratio of telomere to single-copy gene (T/S).

Results

A total of 128 PWH were included in the prospective 6-year observational study. These same 128 PWH (median age, 55 years; 27.3% women) were compared cross-sectionally at 6-year follow-up with 128 age- and gender-matched blood donors (median age, 55 years) and 128 gender-matched individuals older than 60 years from a general population cohort (median age, 70 years). An inverse correlation between age and BTL was observed. The median BTL of PWH was shorter than their matched blood donors (T/S, 1.07 [IQR, 0.95-1.17] vs 1.28 [IQR, 1.12-1.48]; P < .001) but longer than the elderly population (T/S, 0.89 [IQR, 0.77-0.98], P < .001). PWH experienced a BTL increase at 6 years of 2.9% (T/S, 1.04 vs 1.07; P = .002). In PWH, age was associated with a shorter BTL (coefficient, -0.007 45, SE = 0.002 04, P = .002) and baseline lower CD4 count with a gain in BTL (coefficient, -0.000 06, SE = 0.000 02, P = .004). Shorter baseline BTL (odds ratio, 0.91 [95% CI, .87-.94]; P < .001) and higher glucose levels (odds ratio, 1.04 [95% CI, 1.02-1.07]; P = .003) were associated with a greater similarity of BTL to the elderly population.

Conclusions

PWH with long-term virologic suppression experience a trend toward an increased BTL after 6 years of follow-up. Middle-aged people with long-term controlled HIV-1 have a shorter BTL than expected for their chronologic age but longer than that of people 15 years older in the general population.

Sex as a biological variable in ageing: insights and perspectives on the molecular and cellular hallmarks

Sex-specific differences in lifespan and ageing are observed in various species. In humans, women generally live longer but are frailer and suffer from different age-related diseases compared to men. The hallmarks of ageing, such as genomic instability, telomere attrition or loss of proteostasis, exhibit sex-specific patterns. Sex chromosomes and sex hormones, as well as the epigenetic regulation of the inactive X chromosome, have been shown to affect lifespan and age-related diseases. Here we review the current knowledge on the biological basis of sex-biased ageing. While our review is focused on humans, we also discuss examples of model organisms such as the mouse, fruit fly or the killifish. Understanding these molecular differences is crucial as the elderly population is expected to double worldwide by 2050, making sex-specific approaches in the diagnosis, treatment, therapeutic development and prevention of age-related diseases a pressing need.

Fitness consequences of depressive symptoms vary between generations: Evidence from a large cohort of women across the 20th century

Depression has strong negative impacts on how individuals function, leading to the assumption that there is strong negative selection on this trait that should deplete genetic variation and decrease its prevalence in human populations. Yet, depressive symptoms remain common. While there has been a large body of work trying to resolve this paradox by mapping genetic variation of this complex trait, there have been few direct empirical tests of the core assumption that there is consistent negative selection on depression in human populations. Here, we use a unique long-term dataset from the National Health and Nutrition Examination Survey that spans four generational cohorts (Silent Generation: 1928-1945, Baby Boomers: 1946-1964, Generation X: 1965-1980, and Millenials: 1981-1996) to measure both depression scores and fitness components (lifetime sexual partners, pregnancies, and live births) of women from the United States born between 1938-1994. We not only assess fitness consequences of depression across multiple generations to determine whether the strength and direction of selection on depression has changed over time, but we also pair these fitness measurements with mixed models to assess how several important covariates, including age, body mass, education, race/ethnicity, and income might influence this relationship. We found that, overall, selection on depression was positive and the strength of selection changed over time-women reporting higher depression had relatively more sexual partners, pregnancies, and births except during the Silent Generation when selection coefficients neared zero. We also found that depression scores and fitness components differed among generations-Baby Boomers showed the highest severity of depression and the most sexual partners. These results were not changed by the inclusion of covariates in our models. A limitation of this study is that for the Millenials, reproduction has not completed and data for this generation is interrupted by right censoring. Most importantly, our results undermine the common belief that there is consistent negative selection on depression and demonstrate that the relationship between depression and fitness changes between generations, which may explain its maintenance in human populations.

Associations of daily eating frequency and nighttime fasting duration with biological aging in National Health and Nutrition Examination Survey (NHANES) 2003-2010 and 2015-2018

BACKGROUND

Information on the influences of daily eating frequency (DEF) and nighttime fasting duration (NFD) on biological aging is minimal. Our study investigated the potential associations of DEF and NFD with accelerated aging.

METHODS

Out of 24212 participants in NHANES 2003-2010 and 2015-2018, 4 predicted age metrics [homeostatic dysregulation (HD), Klemera-Doubal method (KDM), phenoAge (PA), and allostatic load (AL)] were computed based on 12 blood chemistry parameters. Utilizing 24-h dietary recall, DEF was measured by the frequency of eating occurrences, while NFD was determined by assessing the timing of the initial and final meals throughout the day. Weighted multivariate linear regression models and restricted cubic spline (RCS) were utilized to examine the associations.

RESULTS

Compared to DEF of ≤ 3.0 times, subjects with DEF ≥ 4.6 times demonstrated lower KDM residual [β: -0.57, 95% confidence-interval (CI): (-0.97, -0.17)] and PA residual [β: -0.47, 95% CI: (-0.69, -0.25)]. In comparison to NFD between 10.1 and 12.0 h, individuals with NFD ≤ 10.0 h were at higher HD [β: 0.03, 95% CI: (0.01, 0.04)], KDM residual [β: 0.34, 95% CI: (0.05, 0.63)], and PA residual [β: 0.38, 95% CI: (0.18, 0.57)]. Likewise, those with NFD ≥ 14.1 h also had higher HD [β: 0.02, 95% CI: (0.01, 0.04)] and KDM residual [β: 0.33, 95% CI: (0.03, 0.62)]. The results were confirmed by the dose-response relationships of DEF and NFD with predicted age metrics. Lactate dehydrogenase (LDH) and globulin (Glo) were acknowledged as implicated in and mediating the relationships.

CONCLUSIONS

DEF below 3.0 times and NFD less than 10.0 or more than 14.1 h were independently associated with higher predicted age metrics.

Searching for Beauty and Health: Aging in Women, Nutrition, and the Secret in Telomeres

Women typically outlive men, yet they often experience greater frailty and a higher incidence of chronic diseases as they age. By exploring the biological foundations of aging, with a particular focus on telomere dynamics, this manuscript aims to describe how dietary and lifestyle choices can significantly influence the aging process. The review comprehensively examines current research, underscoring the power of nutrition to counteract age-related changes, support healthy aging, and maintain vitality and beauty in women. The exploration of telomeres-the protective caps at the ends of chromosomes-reveals how they serve as markers of cellular aging and are potential targets for interventions aimed at enhancing women's longevity and quality of life. This study also emphasizes the importance of sex-specific approaches and precision medicine in understanding the unique health challenges women face as they age. By proposing targeted strategies, the review seeks to address these challenges, offering insights into preventive measures that can foster resilience, promote well-being, and extend healthy life expectancy in women. Ultimately, this work provides a sophisticated understanding of the aging process in women, highlighting the pivotal role of tailored interventions in preserving both health and beauty.

Long-term persistence of mitochondrial dysfunctions after viral infections and antiviral therapies: A review of mechanisms involved

Mitochondria are vital for most cells' functions. Viruses hijack mitochondria machinery for misappropriation of energy supply or to bypass defense mechanisms. Many of these mitochondrial dysfunctions persist after recovery from treated or untreated viral infections, particularly when mitochondrial DNA is permanently damaged. Quantitative defects and structural rearrangements of mitochondrial DNA accumulate in post-mitotic tissues as recently reported long after SARS-CoV-2 or HIV infection, or following antiviral therapy. These observations are consistent with the "hit-and-run" concept proposed decades ago to explain viro-induced cell transformation and it could apply to delayed post-viral onsets of symptoms and advocate for complementary supportive care. Thus, according to this concept, following exposure to viruses or antiviral agents, mitochondrial damage could evolve into an autonomous clinical condition. It also establishes a pathogenic link between communicable and non-communicable chronic diseases.

A Framework for an Effective Healthy Longevity Clinic

In the context of an aging global population and the imperative for innovative healthcare solutions, the concept of longevity clinics emerges as a timely and vital area of exploration. Unlike traditional medical facilities, longevity clinics offer a unique approach to preclinical prevention, focusing on "prevention of prevention" through the utilization of aging clocks and biomarkers from healthy individuals. This article presents a comprehensive overview of longevity clinics, encompassing descriptions of existing models, the development of a proposed framework, and insights into biomarkers, wearable devices, and therapeutic interventions. Additionally, economic justifications for investing in longevity clinics are examined, highlighting the significant growth potential of the global biotechnology market and its alignment with the goals of achieving active longevity. Anchored by an Analytical Center, the proposed framework underscores the importance of data-driven decision-making and innovation in promoting prolonged and enhanced human life. At present, there is no universally accepted standard model for longevity clinics. This absence highlights the need for additional research and ongoing improvements in this field. Through a synthesis of scientific research and practical considerations, this article aims to stimulate further discussion and innovation in the field of longevity clinics, ultimately contributing to the advancement of healthcare practices aimed at extending and enhancing human life.

U-shaped association between sleep duration and biological aging: Evidence from the UK Biobank study

Previous research on sleep and aging largely has failed to illustrate the optimal dose-response curve of this relationship. We aimed to analyze the associations between sleep duration and measures of predicted age. In total, 241,713 participants from the UK Biobank were included. Habitual sleep duration was collected from the baseline questionnaire. Four indicators, homeostatic dysregulation (HD), phenoAge (PA), Klemera-Doubal method (KDM), and allostatic load (AL), were chosen to assess predicted age. Multivariate linear regression models were utilized. The association of sleep duration and predicted age followed a U-shape (All p for nonlinear <0.05). Compared with individuals who sleep for 7 h/day, the multivariable-adjusted beta of ≤5 and ≥9 h/day were 0.05 (95% CI 0.03, 0.07) and 0.03 (95% CI 0.02, 0.05) for HD, 0.08 (95% CI 0.01, 0.14) and 0.36 (95% CI 0.31, 0.41) for PA, and 0.21 (95% CI 0.12, 0.30) and 0.30 (95% CI 0.23, 0.37) for KDM. Significant independent and joint effects of sleep and cystatin C (CysC) and gamma glutamyltransferase (GGT) on predicted age metrics were future found. Similar results were observed when conducting stratification analyses. Short and long sleep duration were associated with accelerated predicted age metrics mediated by CysC and GGT.

Multiscale and multidisciplinary analysis of aging processes in bone

The world population is increasingly aging, deeply affecting our society by challenging our healthcare systems and presenting an economic burden, thus turning the spotlight on aging-related diseases: exempli gratia, osteoporosis, a silent disease until you suddenly break a bone. The increase in bone fracture risk with age is generally associated with a loss of bone mass and an alteration in the skeletal architecture. However, such changes cannot fully explain increased fragility with age. To successfully tackle age-related bone diseases, it is paramount to comprehensively understand the fundamental mechanisms responsible for tissue degeneration. Aging mechanisms persist at multiple length scales within the complex hierarchical bone structure, raising the need for a multiscale and multidisciplinary approach to resolve them. This paper aims to provide an overarching analysis of aging processes in bone and to review the most prominent outcomes of bone aging. A systematic description of different length scales, highlighting the corresponding techniques adopted at each scale and motivating the need for combining diverse techniques, is provided to get a comprehensive description of the multi-physics phenomena involved.

Effect of Modifiable Lifestyle Factors on Biological Aging

Biological age is a concept that uses bio-physiological parameters to account for individual heterogeneity in the biological processes driving aging and aims to enhance the prediction of age-related clinical conditions compared to chronological age. Although engaging in healthy lifestyle behaviors has been linked to a lower mortality risk and a reduced incidence of chronic diseases, it remains unclear to what extent these health benefits result from slowing the pace of the biological aging process. This short review summarized how modifiable lifestyle factors - including diet, physical activity, smoking, alcohol consumption, and the aggregate of multiple healthy behaviors - were associated with established estimates of biological age based on clinical or cellular/molecular markers, including Klemera-Doubal Method biological age, homeostatic dysregulation, phenotypic age, DNA methylation age, and telomere length. In brief, the available studies tend to show a consistent association of lifestyle factors with physiological measures of biological age, while findings regarding molecular-based metrics vary. The limited evidence highlights the need for further research in this field, particularly with a life-course approach.

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.

First ever characterisation of the effects of short telomeres in a Singapore interstitial lung disease cohort

BACKGROUND

Differences in disease behaviour and genotypes are described in Asian and Western interstitial lung disease (ILD) cohorts. Short leukocyte telomere length (LTL) correlates with poor outcomes in Western ILD cohorts but its significance in Asian populations is unknown. We aim to characterise the burden and clinical implications of short LTL in Singaporean ILD patients.

METHODS

Patients diagnosed with ILD at Singapore General Hospital were prospectively recruited and compared against 36 healthy controls. The primary outcome was transplant-free survival. Genomic DNA from peripheral blood was extracted and LTL measured using quantitative polymerase chain reaction assay (qPCR).

RESULTS

Amongst 165 patients, 37% had short LTL. There was a higher proportion of combined pulmonary fibrosis and emphysema (CPFE) patients with short LTL (n = 21, 34.4% vs n = 16, 15.4%; p < 0.001). Short LTL patients had reduced survival at 12-, 24- and 36-months and median survival of 24 months (p < 0.001) which remained significant following adjustment for smoking, GAP Stage and radiological UIP pattern (Hazard Ratio (HR), 2.74; 95%CI:1.46, 5.11; p = 0.002). They had increased respiratory-related mortality and acute exacerbation incidences. Despite similar baseline lung function, short LTL patients had a faster decline in absolute forced vital capacity (FVC) of -105.3 (95% CI: 151.4, -59.1) mL/year compared to -58.2 (95% CI: 82.9, -33.6) mL/year (p < 0.001) in normal LTL patients.

CONCLUSION

Short LTL correlated with increased mortality and faster lung function decline in our Singaporean ILD cohort with a magnitude similar to that in Western ILD cohorts. Further research is needed to integrate LTL assessment into clinical practice.

Telomere length and cancer risk: finding Goldilocks

Telomeres are the nucleoprotein complex at chromosome ends essential in genomic stability. Baseline telomere length (TL) is determined by rare and common germline genetic variants but shortens with age and is susceptible to certain environmental exposures. Cellular senescence or apoptosis are normally triggered when telomeres reach a critically short length, but cancer cells overcome these protective mechanisms and continue to divide despite chromosomal instability. Rare germline variants in telomere maintenance genes cause exceedingly short telomeres for age (< 1st percentile) and the telomere biology disorders, which are associated with elevated risks of bone marrow failure, myelodysplastic syndrome, acute myeloid leukemia, and squamous cell carcinoma of the head/neck and anogenital regions. Long telomeres due to rare germline variants in the same or different telomere maintenance genes are associated with elevated risks of other cancers, such as chronic lymphocytic leukemia or sarcoma. Early epidemiology studies of TL in the general population lacked reproducibility but new methods, including creation of a TL polygenic score using common variants, have found longer telomeres associated with excess risks of renal cell carcinoma, glioma, lung cancer, and others. It has become clear that when it comes to TL and cancer etiology, not too short, not too long, but "just right" telomeres are important in minimizing cancer risk.

Monochrome Multiplex Quantitative PCR Telomere Length Measurement

Telomeres are ribonucleoprotein structures at the end of all eukaryotic chromosomes that protect DNA from damage and preserve chromosome stability. Telomere length (TL) has been associated with various exposures, biological processes, and health outcomes. This article describes the monochrome multiplex quantitative polymerase chain reaction (MMqPCR) assay protocol routinely conducted in our laboratory for measuring relative mean TL from human DNA. There are several different PCR-based TL measurement methods, but the specific protocol for the MMqPCR method presented in this publication is repeatable, efficient, cost-effective, and suitable for population-based studies. This detailed protocol outlines all information necessary for investigators to establish this assay in their laboratory. In addition, this protocol provides specific steps to increase the reproducibility of TL measurement by this assay, defined by the intraclass correlation coefficient (ICC) across repeated measurements of the same sample. The ICC is a critical factor in evaluating expected power for a specific study population; as such, reporting cohort-specific ICCs for any TL assay is a necessary step to enhance the overall rigor of population-based studies of TL. Example results utilizing DNA samples extracted from peripheral blood mononuclear cells demonstrate the feasibility of generating highly repeatable TL data using this MMqPCR protocol.

Investigating the association between blood metabolites and telomere length: A mendelian randomization study

BACKGROUND

Telomere length refers to the protective cap at the end of chromosomes, and it plays a crucial role in many diseases. The objective of this study is to explore the relationship between blood metabolites and telomere length, aiming to identify novel biological factors that influence telomere length.

METHODS

In this study, we extracted genome-wide association study (GWAS) data for blood metabolites from a sample of 7824 Europeans. Additionally, GWAS data for telomere length were obtained from the Open GWAS database (GWAS ID: ieu-b-4879). The primary analysis of this study utilized the random inverse variance weighted (IVW) method. Complementary analyses were also conducted using the MR-Egger and weighted median approaches. Sensitivity analyses were performed to assess the robustness of the findings. These included the Cochran Q test, MR-Egger intercept test, MR-PRESSO, and leave-one-out analysis. To investigate the possibility of reverse causation, reverse MR analysis was conducted. Additionally, multivariable MR was utilized to evaluate the direct effect of metabolites on telomere length.

RESULTS

The results suggested a potential association between 15-methylpalmitate, taurocholate, levulinate, and X-12712 and telomere length. MVMR analysis further showed that 15-methylpalmitate, taurocholate, and levulinate can directly influence telomere length, regardless of other metabolites.

CONCLUSIONS

This study suggests that 15-methylpalmitate, taurocholate, and levulinate are likely factors correlated with telomere length. These findings will contribute to the development of strategies for protecting telomeres, preventing related diseases, and establishing a new biological foundation for achieving healthy aging.

Genetically determined telomere length as a risk factor for hematological malignancies: evidence from Mendelian randomization analysis

BACKGROUND

Over the past years, the exact correlation between telomere length and hematological malignancies was still not fully understood.

METHODS

We performed a two-sample Mendelian randomization study to investigate the causal relationship between telomere length and hematological malignancies. We selected genetic instruments associated with telomere length. The genetic associations for lymphoid and hematopoietic malignant neoplasms were obtained from the most recent publicly accessible FinnGen study R9 data. Inverse variant weighted (IVW) analysis was adopted as the primary method, and we also performed the weighted-median method and the MR-Egger, and MRPRESSO methods as sensitive analysis.

RESULTS

Significant associations have been observed between telomere length and primary lymphoid (IVW: OR = 1.52, P = 2.11 × 10-6), Hodgkin lymphoma (IVW: OR = 1.64, P = 0.014), non-Hodgkin lymphoma (IVW: OR = 1.70, P = 0.002), B-cell lymphoma (IVW: OR = 1.57, P = 0.015), non-follicular lymphoma (IVW: OR = 1.58, P = 1.7 × 10-3), mantle cell lymphoma (IVW: OR = 3.13, P = 0.003), lymphoid leukemia (IVW: OR = 2.56, P = 5.92E-09), acute lymphocytic leukemia (IVW: OR = 2.65, P = 0.021) and chronic lymphocytic leukemia (IVW: OR = 2.80, P = 8.21 × 10-6), along with multiple myeloma (IVW: OR = 1.85, P = 0.016).

CONCLUSION

This MR study found a significant association between telomere length and a wide range of hematopoietic malignancies. But no substantial impact of lymphoma and hematopoietic malignancies on telomere length has been detected.

Cross-tissue comparison of telomere length and quality metrics of DNA among individuals aged 8 to 70 years

Telomere length (TL) is an important biomarker of cellular aging, yet its links with health outcomes may be complicated by use of different tissues. We evaluated within- and between-individual variability in TL and quality metrics of DNA across five tissues using a cross-sectional dataset ranging from 8 to 70 years (N = 197). DNA was extracted from all tissue cells using the Gentra Puregene DNA Extraction Kit. Absolute TL (aTL) in kilobase pairs was measured in buccal epithelial cells, saliva, dried blood spots (DBS), buffy coat, and peripheral blood mononuclear cells (PBMCs) using qPCR. aTL significantly shortened with age for all tissues except saliva and buffy coat, although buffy coat was available for a restricted age range (8 to 15 years). aTL did not significantly differ across blood-based tissues (DBS, buffy coat, PBMC), which had significantly longer aTL than buccal cells and saliva. Additionally, aTL was significantly correlated for the majority of tissue pairs, with partial Spearman's correlations controlling for age and sex ranging from ⍴ = 0.18 to 0.51. We also measured quality metrics of DNA including integrity, purity, and quantity of extracted DNA from all tissues and explored whether controlling for DNA metrics improved predictions of aTL. We found significant tissue variation: DNA from blood-based tissues had high DNA integrity, more acceptable A260/280 and A260/230 values, and greater extracted DNA concentrations compared to buccal cells and saliva. Longer aTL was associated with lower DNA integrity, higher extracted DNA concentrations, and higher A260/230, particularly for saliva. Model comparisons suggested that incorporation of quality DNA metrics improves models of TL, although relevant metrics vary by tissue. These findings highlight the merits of using blood-based tissues and suggest that incorporation of quality DNA metrics as control variables in population-based studies can improve TL predictions, especially for more variable tissues like buccal and saliva.

Telomere length is not a useful tool for chronological age estimation in animals

Telomeres are short repetitive DNA sequences capping the ends of chromosomes. Telomere shortening occurs during cell division and may be accelerated by oxidative damage or ameliorated by telomere maintenance mechanisms. Consequently, telomere length changes with age, which was recently confirmed in a large meta-analysis across vertebrates. However, based on the correlation between telomere length and age, it was concluded that telomere length can be used as a tool for chronological age estimation in animals. Correlation should not be confused with predictability, and the current data and studies suggest that telomeres cannot be used to reliably predict individual chronological age. There are biological reasons for why there is large individual variation in telomere dynamics, which is mainly due to high susceptibility to a wide range of environmental, but also genetic factors, rendering telomeres unfeasible as a tool for age estimation. The use of telomeres for chronological age estimation is largely a misguided effort, but its occasional reappearance in the literature raises concerns that it will mislead resources in wildlife conservation.

The dual role of the DREAM/G2M pathway in non-tumorigenic immortalization of senescent cells

Anti-aging and tumorigenesis share common genes and pathways, and thus targeting these genes as part of anti-aging interventions carries the risk of tumorigenesis. It is essential to understand the gene signatures that balance tumorigenesis and aging. To achieve this goal, we analyzed RNA-sequencing data from three non-tumorigenic immortalized cell lines that spontaneously escaped from senescence. By single sample gene set enrichment assay (ssGSEA) and GSEA analysis, we found that both cell growth signaling (E2F targets, MYC targets) and tumor surveillance mechanisms (DNA repair, G2M checkpoint, mitotic spindle) were up-regulated in all three cell lines, suggesting that these genes are potential signatures for non-tumorigenic immortalization. Further analysis revealed that the 182 commonly up-regulated genes in these three cell lines overlapped with the DREAM/G2M pathway, which is known to be the upstream regulator of E2F, Myc targets, DNA repair, G2M checkpoint and mitotic spindle pathways in its cell cycle activation or inhibitory form. By western blotting, quantitative PCR and co-immunoprecipitation, we verified that both forms of the DREAM pathway are up-regulated in all three cell lines; this pathway facilitates control of cell cycle progression, supporting a new mechanism for non-tumorigenic immortalization. Thus, we propose that the DREAM/G2M pathway plays important dual roles with respect to preventing tumorigenesis in the process of immortalization. Our data might serve as the basis for the identification of new signature pathways or gene biomarkers for non-tumorigenic immortalization, and may aid in the discovery of new targets for tumor-free anti-aging drug screening.

Early origins of health and disease risk: The case for investigating adverse exposures and biological aging in utero, across childhood, and into adolescence

In this article, we suggest that aging and development are two sides of the same coin, and that developing a comprehensive understanding of health and disease risk requires examining age-related processes occurring throughout the earliest years of life. Compared to other periods in life, during this early period of acute vulnerability, when children's biological and regulatory systems are developing, biological aging occurs most rapidly. We review theory and empirical research suggesting that processes of development and aging are intricately linked, and that early adversity may program biological parameters for accelerated aging and disease risk early in life, even though clinical signs of age-related disease onset may not be evident until many years later. Following from this, we make the case for widespread incorporation of biological aging constructs into child development research.

Associations between the New DNA-Methylation-Based Telomere Length Estimator, the Mediterranean Diet and Genetics in a Spanish Population at High Cardiovascular Risk

Biological aging is a relevant risk factor for chronic diseases, and several indicators for measuring this factor have been proposed, with telomere length (TL) among the most studied. Oxidative stress may regulate telomere shortening, which is implicated in the increased risk. Using a novel estimator for TL, we examined whether adherence to the Mediterranean diet (MedDiet), a highly antioxidant-rich dietary pattern, is associated with longer TL. We determined TL using DNA methylation algorithms (DNAmTL) in 414 subjects at high cardiovascular risk from Spain. Adherence to the MedDiet was assessed by a validated score, and genetic variants in candidate genes and at the genome-wide level were analyzed. We observed several significant associations (p < 0.05) between DNAmTL and candidate genes (TERT, TERF2, RTEL1, and DCAF4), contributing to the validity of DNAmTL as a biomarker in this population. Higher adherence to the MedDiet was associated with lower odds of having a shorter TL in the whole sample (OR = 0.93; 95% CI: 0.85-0.99; p = 0.049 after fully multivariate adjustment). Nevertheless, this association was stronger in women than in men. Likewise, in women, we observed a direct association between adherence to the MedDiet score and DNAmTL as a continuous variable (beta = 0.015; SE: 0.005; p = 0.003), indicating that a one-point increase in adherence was related to an average increase of 0.015 ± 0.005 kb in TL. Upon examination of specific dietary items within the global score, we found that fruits, fish, "sofrito", and whole grains exhibited the strongest associations in women. The novel score combining these items was significantly associated in the whole population. In the genome-wide association study (GWAS), we identified ten polymorphisms at the suggestive level of significance (p < 1 × 10-5) for DNAmTL (intergenics, in the IQSEC1, NCAPG2, and ABI3BP genes) and detected some gene-MedDiet modulations on DNAmTL. As this is the first study analyzing the DNAmTL estimator, genetics, and modulation by the MedDiet, more studies are needed to confirm these findings.

Telomere Checkpoint in Development and Aging

The maintenance of genome integrity through generations is largely determined by the stability of telomeres. Increasing evidence suggests that telomere dysfunction may trigger changes in cell fate, independently of telomere length. Telomeric multiple tandem repeats are potentially highly recombinogenic. Heterochromatin formation, transcriptional repression, the suppression of homologous recombination and chromosome end protection are all required for telomere stability. Genetic and epigenetic defects affecting telomere homeostasis may cause length-independent internal telomeric DNA damage. Growing evidence, including that based on Drosophila research, points to a telomere checkpoint mechanism that coordinates cell fate with telomere state. According to this scenario, telomeres, irrespective of their length, serve as a primary sensor of genome instability that is capable of triggering cell death or developmental arrest. Telomeric factors released from shortened or dysfunctional telomeres are thought to mediate these processes. Here, we discuss a novel signaling role for telomeric RNAs in cell fate and early development. Telomere checkpoint ensures genome stability in multicellular organisms but aggravates the aging process, promoting the accumulation of damaged and senescent cells.

Telomere Dynamics in Livestock

Telomeres are repeated sequences of nucleotides at the end of chromosomes. They deteriorate across mitotic divisions of a cell. In Homo sapiens this process of lifetime reduction has been shown to correspond with aspects of organismal aging and exposure to stress or other insults. The early impetus to characterize telomere dynamics in livestock related to the concern that aged donor DNA would result in earlier cell senescence and overall aging in cloned animals. Telomere length investigations in dairy cows included breed effects, estimates of additive genetic control (heritability 0.12 to 0.46), and effects of external stressors on telomere degradation across animal life. Evaluation of telomeres with respect to aging has also been conducted in pigs and horses, and there are fewer reports of telomere biology in beef cattle, sheep, and goats. There were minimal associations of telomere length with animal productivity measures. Most, but not all, work in livestock has documented an inverse relationship between peripheral blood cell telomere length and age; that is, a longer telomere length was associated with younger age. Because livestock longevity affects productivity and profitability, the role of tissue-specific telomere attrition in aging may present alternative improvement strategies for genetic improvement while also providing translational biomedical knowledge.