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HER2-enriched tumors are responsible for 20% of breast tumors and have high rates of immune infiltrates in the tumor stroma that respond favorably to neoadjuvant chemotherapy. In the context of tumors, telomeres control cell death and prevent tumor cells from replicating discontinuously, leading to their immortalization. This study aimed to evaluate the presence of tumor-infiltrating lymphocytes, hTERT expression, hTERT promoter mutation, and leukocyte telomere length in HER2-enriched breast tumors. A total of 103 cases were evaluated, 19 with pathologic complete response. The TILs percentage was above ≥10 in 44 cases (43%) and significantly present in patients ≥50 years of age. hTERT staining positivity was mostly nuclear, significantly present in the non-pCR group, and associated with a lower survival rate. Leukocyte telomeres were elongated for HER2-enriched tumors, and in multivariate analysis, shortening was associated with an increased risk of death. Overall, our results show that the nuclear and cytoplasmic presence of hTERT may indicate a worse prognosis and that leukocyte telomere elongation is a protective factor.

Objective Although the etiopathogenesis of preeclampsia (PE) is unknown, evidence suggests that it may be associated with increased oxidative stress. Studies have shown that oxidative stress can affect DNA fragments called telomeres. However, the interactions of PE, oxidative stress, and telomere length are not clearly known. This study aims to evaluate the oxidative/anti-oxidative stress balance in the placenta and umbilical cord and examine the effect of oxidative stress on telomeres. Materials-Method Cord blood and placental samples were collected from 27 pregnant women with severe PE (280/7–336/7 gestational weeks) and 53 healthy pregnant women. Telomere length (TL) was measured by real-time PCR in the cord blood and placenta tissue. Total antioxidant status (TAS) and total oxidant status (TOS) levels were measured in the cord blood and placenta tissue using a colorimetric method. Results No significant differences were found between groups regarding age, BMI, gravida, parity, and newborn gender (p>0.05). Cord blood and placental TL of PE patients were significantly shorter than the control group, while cord blood and placental TAS and TOS levels were higher (p Conclusion This study found that oxidative stress is an independent risk factor in the development of PE and shortens TL in both placental and umbilical cord blood. Future research on telomere homeostasis may offer a new perspective for the treatment of PE.

Telomere length (TL) is a well-known marker of age-related diseases. Oxidative stress and inflammation increase the rate of telomere shortening, triggering cellular senescence. Although lipoproteins could have anti-inflammatory and proinflammatory functional properties, the relationship between lipoprotein particles with TL and telomerase activity-related genes has not been investigated much. In this study, we assessed the associations of lipoprotein subfractions with telomere length, TERT, and WRAP53 expression in a total of 54 pre-diabetic subjects from the EPIRDEM study. We regressed TL, TERT, and WRAP53 on 12 lipoprotein subclasses, employing a Gaussian linear regression method with Lasso penalty to determine a lipoprotein profile associated with telomere-related parameters. The covariates included age, sex, body mass index (BMI), dyslipidemia, statin consumption, and physical activity leisure time. We identified a lipoprotein profile composed of four lipoprotein subfractions associated with TL (Pearson r = 0.347, p-value = 0.010), two lipoprotein subfractions associated with TERT expression (Pearson r = 0.316, p-value = 0.020), and five lipoprotein subfractions associated with WRAP53 expression (Pearson r = 0.379, p-value =0.005). After adjusting for known confounding factors, most lipoprotein profiles maintained the association with TL, TERT, and WRAP53. Overall, medium and small-sized HDL particles were associated with shorter telomeres and lower expression of TERT and WRAP53. Large HDL particles were associated with longer telomere and lower expression of WRAP53, but not with TERT. Our results suggest that the lipoprotein profiles are associated with telomere length, TERT, and WRAP53 expression and should be considered when assessing the risk of chronic diseases.

Physiological and psychological distress may accelerate cellular aging, manifested by shortening of telomere length (TL). The present study focused on TL shortening in anorexia nervosa (AN), an illness combining physiological and psychological distress. For that purpose, we measured TL in 44 female adolescents with AN at admission to inpatient treatment, in a subset of 18 patients also at discharge, and in 22 controls. No differences in TL were found between patients with AN and controls. At admission, patients with AN-binge/purge type (AN-B/P; n = 18) showed shorter TL compared with patients with AN-restricting type (AN-R; n = 26). No change in TL was found from admission to discharge, despite an improvement in body mass index standard deviation score (BMI-SDS) following inpatient treatment. Older age was the only parameter assessed to be correlated with greater TL shortening. Several methodological changes have to be undertaken to better understand the putative association of shorter TL with B/P behaviors, including increasing the sample size and the assessment of the relevant pathological eating disorder (ED) and non-ED psychological correlates in the two AN subtypes.

AIMS: Aging is accompanied by telomere shortening. Increased telomere shortening is considered a marker of premature aging. Cardiac aging results in the development of cardiac pathologies. Electrocardiogram (ECG) measures reflect cardiac excitation, conduction, and repolarization. ECG measures also prolong with aging and are associated with cardiac pathologies including atrial fibrillation. As premature prolongation of ECG measures is observed, we hypothesized that such prolongation may be associated with telomere length. METHODS AND RESULTS: We studied the large, community-based KORA F4 Study. Of 3,080 participants enrolled between 2006 and 2007 with detailed information on demographic, anthropometric, clinical, and ECG characteristics, 2,575 presented with available data on leukocyte telomere length. Telomere length was determined by real-time quantitative PCR and expressed relative to a single copy gene. We fitted multivariable adjusted linear regression models to associate the ECG measures RR-interval, PR-interval, QRS-duration, and heart rate corrected QTc with telomere length. In our cohort, the mean age was 54.9±12.9 years and 46.6% were men. Increased age was associated with shorter telomere length (p

The telomere length of human blastocysts exceeds that of oocytes and telomerase activity increases after zygotic activation, peaking at the blastocyst stage. Yet, it is unknown whether aneuploid human embryos at the blastocyst stage exhibit a different profile of telomere length, telomerase gene expression, and telomerase activity compared to euploid embryos. In present study, 154 cryopreserved human blastocysts, donated by consenting patients, were thawed and assayed for telomere length, telomerase gene expression, and telomerase activity using real-time PCR (qPCR) and immunofluorescence (IF) staining. Aneuploid blastocysts showed longer telomeres, higher telomerase reverse transcriptase (TERT) mRNA expression, and lower telomerase activity compared to euploid blastocysts. The TERT protein was found in all tested embryos via IF staining with anti-hTERT antibody, regardless of ploidy status. Moreover, telomere length or telomerase gene expression did not differ in aneuploid blastocysts between chromosomal gain or loss. Our data demonstrate that telomerase is activated and telomeres are maintained in all human blastocyst stage embryos. The robust telomerase gene expression and telomere maintenance, even in aneuploid human blastocysts, may explain why extended in vitro culture alone is insufficient to cull out aneuploid embryos during in vitro fertilization.

Senescence, declining physiological function resulting in reduced survival and fertility with increasing age is a widely observed natural phenomena. Many studies of senescence in natural populations have found actuarial and reproductive senescence in wild vertebrates. More recently, evidence of ageing in diverse phenotypic traits has been reported. This has revealed the complex nature of senescence with huge variation in ageing patterns across vital rates and phenotypic traits within a population. Understanding how variation in ageing patterns is generated and maintained is important to understand the evolution of senescence in the wild. Many factors are likely to contribute to variation in ageing patterns observed in the wild and recent studies have highlighted the role of some processes such as – a) tradeoffs between life-history traits underpinning ageing and how molecular markers may behave as a mediator of these tradeoffs; b) the influence of parental age on offspring performance and ageing; c) the role of potential declines in selection with increasing age driving the ageing process across phenotypes in the wild. In this thesis, I set out to investigate some of the proximate and ultimate drivers of variation in senescence in a natural Soay sheep population. In Chapters 2 and 3, I examined the role of a molecular marker, telomere length in mediating tradeoffs between different life-history traits by investigating whether costs of maternal reproductive investment, infection and immunity influence TL. In Chapter 4, I investigated the short- and long-term impact of parental age effects on offspring traits examining the effect of both maternal and paternal age on four offspring traits – a) first-year survival, b) offspring adult lifespan, c) offspring lifetime breeding success and d) offspring lifetime recruitment success. In Chapter 5, I jointly developed evolutionary theory to explain variation in ageing patterns across phenotypic traits within a population (also known as asynchronous ageing) and proposed a methodological framework to estimate age-specific phenotypic selection in natural populations. In Chapter 6, I implemented the methods outlined in Chapter 5 to estimate age-dependent phenotypic selection across six traits in female Soay sheep.

Telomere length, as a biomarker of accelerated aging, is closely related to many chronic diseases. We aimed to explore the association between coffee consumption and telomere length. Our study included 468,924 participants from the UK Biobank. Multivariate linear models (observational analyses) were conducted to evaluate the associations of coffee intake, instant coffee intake, and filtered coffee intake with telomere length. In addition, we evaluated the causality of these associations in Mendelian randomization (MR) analyses by four methods (inverse-variance weighted (IVW), MR pleiotropy residual sum and outlier (MR-PRESSO), MR-Egger, and weighted median). Observational analyses indicated that coffee intake and instant coffee intake were negatively correlated with telomere length, which was equal to 0.12 year of age-related decrease in telomere length for each additional cup of coffee intake (p < 0.001), and 0.38 year of age-related decrease in telomere length for each additional cup of instant coffee intake (p < 0.001), respectively. There was no significant correlation between filtered coffee and telomere length (p = 0.862). Mendelian randomization analyses supported the results of observational analyses. Coffee intake was found to have a causal effect on telomere length through weighted median analysis (p = 0.022), and instant coffee intake had a causal effect on telomere length through IVW analysis (p = 0.019) and MR-PRESSO analysis (p = 0.028). No causal relationship was found between filtered coffee intake and telomere length (p > 0.05). Coffee intake, particularly instant coffee, was found to have an important role in shortening telomere length.

Jun Zhang The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology, Chongqing Eye Institute, Chongqing Branch of National Clinical Research Center for Ocular Diseases, Chongqing, People’s Republic of ChinaCorrespondence: Jun Zhang, Tel/Fax +86-23-89012851, Email zj1018415371@163.comBackground: Telomere maintenance is increasingly being considered as fundamental to the progression of immune-mediated inflammatory diseases. However, the causality underlying the purported relationship has not been fully elucidated. In the present work, we applied Mendelian randomization (MR) analysis to obtain estimates of the causal effect of telomere length (TL) on the risk of juvenile idiopathic arthritis (JIA) and JIA-associated iridocyclitis.Methods: Two-sample MR analysis was conducted using summary-level data from the largest genome-wide association studies concerning TL (78,592 individuals), JIA (6056 cases and 25,086 controls), and JIA-associated iridocyclitis (1430 cases and 9,2767 controls). All the participants were of European ancestry. The inverse variance weighted (IVW) method was applied to estimate the causal effects. Sensitivity analyses incorporating multiple complementary MR approaches were implemented to test the robustness of the association and examine potential bias from pleiotropy.Results: In our MR analysis, genetically predicted shorter TL was associated with an increased risk of JIA (IVW: odds ratio=1.68, 95% CI: 1.13– 2.48, P=0.009), but not with the risk of JIA-associated iridocyclitis (IVW: odds ratio=1.75, 95% CI: 0.81– 3.79, P=0.155). The other MR methods produced consistent results. Besides, a leave-one-out sensitivity analysis yielded similar findings and validated the robustness of the causal relationship. MR-Egger regression revealed no notable horizontal pleiotropy (intercept=0.046, P=0.175).Conclusion: This work provides evidence of a negative association between TL and JIA risk, but not for the association between TL and the risk of JIA-associated iridocyclitis, in a European population. Future studies with larger sample sizes are warranted to elucidate the underlying role of TL in these diseases.Keywords: telomere length, Mendelian randomization, juvenile idiopathic arthritis, JIA-associated iridocyclitis, genetics

Telomere is a unique DNA-protein complex which covers the ends of chromosomes to avoid end fusion and maintain the stability and integrity of chromosomes. Telomere length (TL) shortening has been linked to aging and various age-related diseases in humans. Here we recruited a total of 1031 Chinese individuals aged between 12 and 111 years, including 108 families with parents and their offspring. DNA was extracted from peripheral white blood cells and TL was measured by quantitative PCR (qPCR). We explored the associations of TL with age, gender and clinical variables, and tested the parental effects on TL variation. First, we found that TL was shortened with age, however, TL was better maintained in females than males. Second, there was a robust association of TL between mother and offspring, but not between father and their offspring. In addition, TL was inversely associated with visceral fat index in females, and positively associated with apolipoprotein A levels. Knockdown of the key genes for lipid metabolism (PNPLA2 and CPT1) shortened the TL in HepG2 cells. These findings indicate that TL is maternally inherited, and impairment of lipid metabolism may contribute to the TL shortening in the Chinese population.

Antipsychotics may prolong or retain telomere length, affect mitochondrial function, and then affect the metabolism of nerve cells. To validate the hypothesis that antipsychotics can prolong telomere length after oxidative stress injury, leukocytes from healthy volunteers were extracted using Ficoll-Histopaque density gradient. The mononuclear cells layer was resuspended in cell culture medium. Oxidative stress was induced with hydrogen peroxide in cultured leukocytes. Four days later, leukocytes were treated with aripiprazole, haloperidol or clozapine for 7 days. Real-time PCR revealed that treatments with aripiprazole and haloperidol increased the telomere length by 23% and 20% in peripheral blood mononuclear cells after acute oxidative stress injury. These results suggest that haloperidol and aripiprazole can reduce the damage to telomeres induced by oxidative stress. The experiment procedure was approved by the Ethics Committee of Faculty of Medicine of the University of São Paulo (FMUSP/CAAE approval No. 52622616.8.0000.0065).

As research related to healthspan and lifespan has become a hot topic, the necessity for a reliable and practical biomarker of aging (BoA), which can provide information about mortality and morbidity risk, along with remaining life expectancy, has increased. The chromosome terminus non-coding protective structure that prevents genomic instability is called a telomere. The continual shortening of telomeres, which affects their structure as well as function, is a hallmark of agedness. The aforementioned process is a potential cause of age-related diseases (ARDs), leading to a bad prognosis and a low survival rate, which compromise health and longevity. Hence, studies scrutinizing the BoAs often include telomere length (TL) as a prospective candidate. The results of these studies suggest that TL measurement can only provide an approximate appraisal of the aging rate, and its implementation into clinical practice and routine use as a BoA has many limitations and challenges. Nevertheless, measuring TL while determining other biomarkers can be used to assess biological age. This review focuses on the importance of telomeres in health, senescence, and diseases, as well as on summarizing the results and conclusions of previous studies evaluating TL as a potential BoA. Kako su istraživanja na temu starenja postala sve popularnija, javila se potreba za pouzdanim i praktičnim biomarkerom starenja, koji može pružiti informacije o riziku od mortaliteta i morbiditeta. Telomere su nekodirajući krajevi linearnih hromozoma koji održavaju njihovu stabilnost i integritet. Ćelijsko starenje i starenje organizma karakteriše progresivno skraćivanje telomera, što ugrožava njihovu strukturu i funkciju. Skraćivanje telomera je u vezi sa povećanom incidencom bolesti povezanih sa starenjem i lošom stopom preživljavanja, što ugrožava zdravlje i skraćuje životni vek. Stoga je dužina telomera dugo vremena prepoznata kao jedan od najboljih biomarkera starenja. Međutim, nedavna istraživanja ukazuju na to da dužina telomera može da pruži samo približnu procenu brzine starenja, pa je implementacija ovog biomarkera u kliničku praksu i rutinsku primenu praćena mnogim ograničenjima i izazovima. Uprkos tome, merenje dužine telomera, uz istovremeno određivanje drugih biomarkera, može poslužiti za procenu biološke starosti. Fokus ovog rada je na značaju telomera u ljudskom zdravlju, starenju i bolestima, kao i na sumiranju rezultata i zaključaka dosadašnjih studija koje su se bavile ispitivanjem dužine telomera kao potencijalnog kandidata za biomarker starenja.

Background Telomere length (TL) and its attrition are important indicators of physiological stress and biological aging and hence may vary among individuals of the same age. This variation is apparent even in newborns, suggesting potential effects of parental factors and the intrauterine environment on TL of the growing fetus. Methods Average relative TLs of newborns (cord tissue, N = 950) and mothers (buffy coat collected at 26–28 weeks of gestation, N = 892) were measured in a birth cohort. This study provides a comprehensive analysis of the effects of heritable factors, socioeconomic status, and in utero exposures linked with maternal nutrition, cardiometabolic health, and mental well-being on the newborn TL. The association between maternal TL and antenatal maternal health was also studied. Results Longer maternal TL (β = 0.14, P = 1.99E−05) and higher paternal age (β = 0.10, P = 3.73E−03) were positively associated with newborn TL. Genome-wide association studies on newborn and maternal TLs identified 6 genetic variants in a strong linkage disequilibrium on chromosome 3q26.2 (Tag SNP-LRRC34-rs10936600: Pmeta = 5.95E−08). Mothers with higher anxiety scores, elevated fasting blood glucose, lower plasma insulin-like growth factor-binding protein 3 and vitamin B12 levels, and active smoking status during pregnancy showed a higher risk of giving birth to offspring with shorter TL. There were sex-related differences in the factors explaining newborn TL variation. Variation in female newborn TL was best explained by maternal TL, mental health, and plasma vitamin B12 levels, while that in male newborn TL was best explained by paternal age, maternal education, and metabolic health. Mother’s TL was associated with her own metabolic health and nutrient status, which may have transgenerational effects on offspring TL. Conclusions Our findings provide a comprehensive understanding of the heritable and environmental factors and their relative contributions to the initial setting of TL and programing of longevity in early life. This study provides valuable insights for preventing in utero telomere attrition by improving the antenatal health of mothers via targeting the modifiable factors. Trial registration ClinicalTrials.gov, NCT01174875. Registered on 1 July 2010

[Background]: To investigate the role of cell senescence in systemic sclerosis (SSc), we analyzed telomere shortening (TS) in SSc patients and the effect of targeting DNA damage in the bleomycin model of skin fibrosis. [Results]: Telomere length (TL) in blood leukocytes of 174 SSc patients and 68 healthy controls was measured by Southern blot, and we found shorter age-standardized TL in SSc patients compared to healthy controls. TL was shorter in SSc patients with ILD compared to those without ILD and in anti-topoisomerase I positive compared to anti-centromere positive patients. To analyze the potential role of DNA damage in skin fibrosis, we evaluated the effects of the DNA protective GSE4 peptide in the bleomycin mouse model of scleroderma and the fibrotic response of cultured human dermal fibroblasts. Administration of GSE4-nanoparticles attenuated bleomycin-induced skin fibrosis as measured by Masson’s staining of collagen and reduced Acta2 and Ctgf mRNA expression, whereas transduction of dermal fibroblasts with a lentiviral GSE4 expression vector reduced COL1A1, ACTA2 and CTGF gene expression after stimulation with bleomycin or TGF-β, in parallel to a reduction of the phospho-histone H2A.X marker of DNA damage. [Conclusions]: SSc is associated with TS, particularly in patients with lung disease or anti-topoisomerase I antibodies. Administration of GSE4 peptide attenuated experimental skin fibrosis and reduced fibroblast expression of profibrotic factors, supporting a role for oxidative DNA damage in scleroderma., The authors received financial support from Fondo de Investigación Sanitaria, Instituto de Salud Carlos III (PI19/01129, PI20/00335, and RIER network RD16/0012 RETICS program), co-financed by the European Regional Development Fund (FEDER).

This study aimed to explore the role of telomere length in three different diabetes types: latent autoimmune diabetes of adulthood (LADA), latent autoimmune diabetes in the young (LADY), and type 2 diabetes mellitus (T2DM). A total of 115 patients were included, 72 (62.61%) had LADA, 30 (26.09%) had T2DM, and 13 (11.30%) had LADY. Telomere length was measured using real-time Polymerase Chain Reaction. For statistical analysis, we used the ANOVA test, X2 test, and the Mann–Whitney U test. Patients with T2DM had higher BMI compared to LADA and LADY groups, with a BMI average of 31.32 kg/m2 (p = 0.0235). While the LADA group had more patients with comorbidities, there was not a statistically significant difference (p = 0.3164, p = 0.3315, p = 0.3742 for each of the previously mentioned conditions). There was a difference between those patients with T2DM who took metformin plus any other oral antidiabetic agent and those who took metformin plus insulin, the ones who had longer telomeres. LADA patients had shorter telomeres compared to T2DM patients but not LADY patients. Furthermore, T2DM may have longer telomeres thanks to the protective effects of both metformin and insulin, despite the higher BMI in this group.

This study aimed to evaluate the interrelationship between telomere length, telomerase activity and oxidative DNA damage in patients undergoing in vitro fertilization (IVF). This single-center, observational clinical study comprised 102 unselected, consecutive patients with various infertility diagnoses. Granulosa cells (GCs) and follicular fluid (FF) were analyzed simultaneously for telomere functions and for the marker of oxidative DNA damage, 8-hydroxy-2-deoxyguanosine (8-OHdG). An Absolute Human Telomere Lengths Quantification qPCR Assay kit and Telomerase Activity Quantification qPCR Assay kit (Nucleotestbio, Budapest, Hungary), as well as an 8-OHdG ELISA kit (Abbexa Ltd., Cambridge, United Kingdom) were used for analyses. Similar telomere lengths were found in GCs and FF, however telomerase activity was markedly depressed, while 8-OHdG levels were markedly elevated in FF compared with those in GCs (p < 0.01). Telomere lengths were independent of telomerase activity both in GCs and FF. However, GC 8-OHdG was inversely related to telomerase activity in GCs and FF (p < 0.05). Importantly, 8-OHdG levels both in GCs and FF had significant negative impact on the number of the retrieved and MII oocytes (p < 0.01), whereas FF 8-OHdG was negatively related further to the number of fertilized oocytes and blastocysts (p < 0.01). In conclusion, we could not confirm the direct association of telomere function and reproductive potential. However, oxidative DNA damage, as mainly reflected by 8-OHdG, adversely affected early markers of IVF outcome and clinical pregnancies.

Telomeres shorten with age and shorter leukocyte telomere length (LTL) has been associated with various age-related diseases. Thus, LTL has been considered a biomarker of biological aging. Dyslipidemia is an established risk factor for most age-related metabolic disorders. However, little is known about the relationship between LTL and dyslipidemia. Lipidomics is a new biochemical technique that can simultaneously identify and quantify hundreds to thousands of small molecular lipid species. In a large population comprising 1843 well-characterized American Indians in the Strong Heart Family Study, we examined the lipidomic profile of biological aging assessed by LTL. Briefly, LTL was quantified by qPCR. Fasting plasma lipids were quantified by untargeted liquid chromatography–mass spectrometry. Lipids associated with LTL were identified by elastic net modeling. Of 1542 molecular lipids identified (518 known, 1024 unknown), 174 lipids (36 knowns) were significantly associated with LTL, independent of chronological age, sex, BMI, hypertension, diabetes status, smoking status, bulk HDL-C, and LDL-C. These findings suggest that altered lipid metabolism is associated with biological aging and provide novel insights that may enhance our understanding of the relationship between dyslipidemia, biological aging, and age-related diseases in American Indians. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11357-022-00638-9.

Background Accelerated epigenetic ageing can occur in untreated HIV infection and is partially reversible with effective antiretroviral therapy (ART). We aimed to make a long-term comparison of epigenetic ageing dynamics in people with HIV during untreated HIV infection and during suppressive ART., Methods In this longitudinal study, conducted over 17 years in HIV outpatient clinics in Switzerland, we applied 5 established epigenetic age estimators (epigenetic clocks) in peripheral blood mononuclear cells (PBMCs) in Swiss HIV Cohort Study participants before or during suppressive ART. All participants had a longitudinal set of PBMC samples available at four timepoints (T1-T4). T1 and T2 had to be 3 years or longer apart, as did T3 and T4. We assessed epigenetic age acceleration (EAA) and a novel rate of epigenetic ageing., Findings Between March 13, 1990, and Jan 18, 2018, we recruited 81 people with HIV from the Swiss HIV Cohort Study. We excluded one participant because a sample did not meet quality checks (transmission error). 52 (65%) of 80 patients were men, 76 (95%) were white, and the median patient age was 43 (IQR 37 center dot 5-47) years. Per year of untreated HIV infection (median observation 8 center dot 08 years, IQR 4 center dot 83-11 center dot 09), mean EAA was 0 center dot 47 years (95% CI 0 center dot 37 to 0 center dot 57) for Horvath's clock, 0 center dot 43 years (0 center dot 3 to 0 center dot 57) for Hannum's clock, 0 center dot 36 years (0 center dot 27 to 0 center dot 44) for SkinBlood clock, and 0 center dot 69 years (0 center dot 51 to 0 center dot 86) for PhenoAge. Per year of suppressive ART (median observation 9 center dot 8 years, IQR 7 center dot 2-11), mean EAA was -0 center dot 35 years (95% CI -0 center dot 44 to -0 center dot 27) for Horvath's clock, -0 center dot 39 years (-0 center dot 50 to -0 center dot 27) for Hannum's clock, -0 center dot 26 years (-0 center dot 33 to -0 center dot 18) for SkinBlood clock, and -0 center dot 49 years (-0 center dot 64 to -0 center dot 35) for PhenoAge. Our findings indicate that people with HIV epigenetically aged by a mean of 1 center dot 47 years for Horvath's clock, 1 center dot 43 years for Hannum's clock, 1 center dot 36 years for SkinBlood clock, and 1 center dot 69 years for PhenoAge per year of untreated HIV infection; and 0 center dot 65 years for Horvath's clock, 0 center dot 61 years for Hannum's clock, 0 center dot 74 years for SkinBlood clock, and 0 center dot 51 years for PhenoAge, per year of suppressive ART. GrimAge showed some change in the mean EAA during untreated HIV infection (0 center dot 10 years, 0 center dot 02 to 0 center dot 19) and suppressive ART (-0 center dot 05 years, -0 center dot 12 to 0 center dot 02). We obtained very similar results using the rate of epigenetic ageing. Contribution of multiple HIV-related, antiretroviral, and immunological variables, and of a DNA methylation-associated polygenic risk score to EAA was small., Interpretation In a longitudinal study over more than 17 years, epigenetic ageing accelerated during untreated HIV infection and decelerated during suppressive ART, highlighting the importance of limiting the duration of untreated HIV infection.

Background: Preeclampsia (PE) is a “multifactorial syndrome” in which ambient air pollution may contribute to the etiology of PE. However, the underlying mechanism of this association is not clearly elucidated. This dissertation aims at understanding the placental molecular mechanism underlying the relationship of prenatal exposure to ambient air pollution with preeclampsia and fetal growth by characterizing and evaluating the mediator role of placental aging using mitochondrial DNA content, telomere length, DNA methylation and gene expression analyses.Methods: Scania in Sweden and Barcelona in Spain are the two main study areas. Maternal Air Pollution in Southern Sweden (MAPSS) is a population-based cohort consisting of 43,688 singleton pregnancies recorded from 2000 to 2009 in Scania, Sweden. For placental molecular studies, we selected a sub- cohort of 361 mother-child pairs from the Barcelona Life Study Cohort (BiSC), a prospective cohort consisting of 1080 mother-child pairs recruited between 2018 and 2021 as well as 137 participants from unique biobank designed to study PE at Lund University. Each individual-level air pollutant concentrations were estimated either by a high-resolution dispersion model or by a passive sampling methods. Placental mtDNAcn and TL were measured using qPCR. Placental DNAm and gene expression were analyzed with EPIC array and RNA-seq, respectively. Linear, logistic regression and linear mixed effects models were used on SPSS and R statistical programs.Results: In a setting with fair air quality in Scania, the increased risk of PE and SGA were associated with both linear exposure trend and quartile-specific exposure of ambient particles and NOx. In a setting with moderate air quality in Barcelona, early pregnancy exposure to ambient NO2 measured by home- outdoor and personal sensors were associated with lower birth weight and increased odds of having SGA neonate. Although the mediatory role of placental mtDNAcn and telomere length were not confirmed, prenatal exposure to ambient NOx and NO2 affect the placental aging process differently depending on the exposure concentration and exposure period during pregnancy. We observed reduced mtDNAcn and shorter TL in placenta in relation to exposure during first trimester, whereas increased mtDNAcn in relation to NO2 exposure during third trimester. Prenatal exposure to ambient NOx during first trimester affected differential placental DNA methylation in PE and NOx combined groups, resulting in placental age deceleration and showing sexual dimorphism.Conclusion: Placental senescence and aging may be the underlying molecular mechanism linking the association between prenatal exposure to ambient air pollution and pregnancy complications including preeclampsia and small-for-gestational age foetuses and neonates.

IntroductionHypercaloric nutrition and physical inactivity cause obesity, a potential driver of myocardial apoptosis and senescence that may accelerate cardiac aging. Although physical activity reduces mortality, its impact on myocardial aging is insufficiently understood. Here we investigated the effects of a hypercaloric high-fat diet (HFD) and regular exercise training on cardiac cells telomeres and histomorphometric indices of cardiac aging.MethodsNinety-six 4-months old female Sprague-Dawley rats were fed for 10 months normal (ND) or a HFD diet. Half of the animals in each group performed 30 min treadmill-running sessions on 5 consecutive days per week. At study end, cardiomyocyte cross-sectional area (CSA), interstitial collagen content, vascular density, apoptotic and senescent cells, relative telomere length (RTL), and expression of telomerase-reverse transcriptase (Tert) as marker of telomere-related senescence and apoptosis were analyzed.ResultsCompared to ND, the HFD group developed obesity, higher CSA, lower capillary density and tended to have more apoptotic cardiomyocytes and interstitials cells. Myocardial RTL and the expression of Terf-1 and Terf-2 were comparable in sedentary HFD and ND animals. In the HFD group, regular moderate endurance exercise improved myocardial vascularization, but had no effect on CSA or apoptosis. Notably, the combination of exercise and HFD increased senescence when compared to sedentary ND or HFD, and reduced RTL when compared to exercise ND animals. Exercising HFD animals also showed a trend toward higher Tert expression compared to all other groups. In addition, exercise reduced Terf-1 expression regardless of diet.ConclusionHFD-induced obesity showed no effects on myocardial telomeres and induced only mild morphologic alterations. Summarized, long-term moderate endurance exercise partially reverses HFD-induced effects but may even trigger cardiac remodeling in the context of obesity.

Карцином плућа је други најприсутнији карцином у свету са петогодишњим преживљавањем мањим од 15%. Може се поделити у две клиничко-патолошке групе на микроцелуларни и немикроцелуларни карцином плућа. Процес туморогенезе праћен је различитим променама у дужини теломера и редокс статусу ових пацијената. Теломере су некодирајући терминални сегменти хромозома, који се доводе у везу са биолошким старењем. На њихову дужину могу да утичу различити фактори, па тако и оксидативни стрес, који кроз иницијацију канцерогенезе доприноси њиховом скраћивању. Lung cancer is the second most common cancer worldwide with a five-year life expectancy of less than 15%. It can be divided into two clinicopathological groups: small cell lung carcinoma (SCLC) and non-small cell lung carcinoma. Tumorigenesis is accompanied by various changes in telomere length and redox status of patients. Telomeres are non-coding segments of the chromosome that are associated with biological ageing. Telomere length can be affected by various factors such as oxidative stress. Oxidative stress may contribute to telomere degradation by triggering carcinogenesis.

In the present study, we will use data from the UK Biobank (UKB) to investigate whether i) menopause (yes/no) or ii) menopause type (natural/surgical) is associated with markers of cellular age (i.e., shorter leukocyte telomere length; LTL) and brain age gap (BAG; higher white matter brain BAG and grey matter BAG). Furthermore, we will evaluate whether menopause/menopause type and a history of depression together are associated with shorter LTL and higher white and grey matter BAG. See full introduction in attached PDF for more information.

Telomeres are the conservative sequence repeats located at the end of linear chromosomes that have been the focus of intensive research across many disciplines over the last four decades. They function as a cap to protect the chromosome ends from fusion to other chromosomes and to prevent chromosome degradation. Telomere shortening is thought to be involved in ageing, reflecting or even causing age-related dysregulation of bodily functions. Telomere length and telomere shortening have also gained considerable interest in the field of ecology and evolution as indicators of individual quality and mediators of life-history trade-offs. Telomere length (TL) predicts life span in many animal species but there is considerable variation in TL and shortening rate between individuals, populations and species. How does this variation come about and how is it maintained? Paper I in this thesis discusses the most prominent hypotheses in ecology and evolution that have been put forward to explain variation in TL and telomere dynamics (i.e., shortening and elongation of telomeres). It presents a framework that groups the different hypotheses based on research question or their underlying assumptions about the causal effects of telomeres on organism performance. Some of the key issues that are highlighted in this synthesis paper are that 1) the question of whether telomeres have a causal effect on ageing and life span is still debated, 2) the costs of telomere shortening and elongation remain elusive, and 3) the genetic and non-genetic contribution to variation in TL (and therefore the potential for selection to act on TL) is still not fully understood. The papers III-V in this thesis try to tackle some of these questions. Paper III aims to test whether mild inflammation (induced through repeated immune challenges), can have measurable negative effects on TL, both over the short- and the long-term and whether this results in concomitant deterioration in physiological health. To measure physiological health, we use the measurement method based on the VetScan blood analyser, which is introduced and carefully evaluated for broader use in paper II. Immune system activation had no measurable effects on TL, but the change in ambient and social environment as a consequence of the experiment design (from harsh, rather cold and large-group to benign, thermoneutral and same-sexed pairs conditions), appeared to induce substantial telomere elongation (up to 150 % increase) in the individuals with the shortest TLs. This supports the hypotheses that telomere restoration is costly and therefore primarily occurs under benign conditions. Moreover, telomere elongation occurred more frequently among individuals with the shortest TL, possibly because such individuals are closer to the lower critical threshold in TL. Paper IV and V investigate the genetic and non-genetic contribution to the variation in TL. By creating parental groups that were based on the individuals with the shortest and longest TL at birth in the population (thus manipulating the expected genetic contribution from parents to offspring) it was possible to test how genetic and non-genetic parental effects contribute to TL during the prenatal and early post-natal life stages. The results show that offspring TL at birth, but not embryo TL, was predicted by parental early-life TL group. These results are not consistent with hypotheses assuming that telomere trajectories can be predicted based on TL at the very early stages of embryonic development. However, they support the idea that telomere shortening rate rather than TL itself is inherited. To study this further, paper V examines inheritance patterns of telomere length in detail using both animal model and parent-offspring regressions. The study shows that heritability estimates of TL are moderate magnitude, and, particularly, that these estimates vary considerably depending on at which life stage/age TL measurements were compared between parents and offspring. Altogether, this thesis presents a number of novel findings that both confirm and challenge some of the current ‘telomere hypotheses’ discussed in paper I.

im: This study aimed to evaluate the effect of anthropometric measurements and dietary habits on telomere length in healthy older residents in rural and urban areas. Methods: This was a cross-sectional study. The study population included 81 healthy older individuals aged ≥80 years. A quantitative food frequency questionnaire was used to determine dietary habits. Anthropometric measurements were taken by researchers. The telomere length of individuals was determined from leukocytes using quantitative polymerase chain reaction. Results: Urban women had longer telomeres than rural women (P < 0.05). Rural men had significantly higher hip circumference, middle-upper arm circumference and fat-free mass than urban men (P < 0.05). It was shown that while fresh vegetable consumption was higher in rural areas, carbonated drink consumption was higher in urban areas (P < 0.05). In women, homemade bread and sugar consumption were higher in rural areas, and honey consumption was higher in urban (P < 0.05). Red meat, milk-based dessert and pastry consumption explain telomere shortening by 22.5%, 24.8% and 17.9%, respectively. In addition, the model based on anthropometric measurements also contributes to explaining telomere shortening by 42.9%. Conclusion: Red meat, milk-based dessert and pastry consumption, and waist circumference, hip circumference, waist-to-hip ratio and waist-to-height ratio are associated with telomere length. Longer telomeres are associated with a healthy, balanced, adequate diet and maintaining a healthy body weight/proportion, and they are crucial for achieving healthy aging.

Background: Particulate matter (PM) is associated with aging markers at birth, including telomeres and mito-chondria. It is unclear whether markers of the core-axis of aging, i.e. tumor suppressor p53 (p53) and peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1 alpha), are associated with prenatal air pollution and whether there are underlying mechanisms.Methods: 556 mother-newborn pairs from the ENVIRONAGE birth cohort were recruited at the East Limburg Hospital in Genk (Belgium). In placenta and cord blood, telomere length (TL) and mitochondrial DNA content (mtDNAc) were measured using quantitative real-time polymerase chain reaction (qPCR). In cord plasma, p53 and PGC-1 alpha protein levels were measured using ELISA. Daily ambient PM2.5 concentrations during gestation were calculated using a spatial temporal interpolation model. Distributed lag models (DLMs) were applied to assess the association between prenatal PM2.5 exposure and each molecular marker. Mediation analysis was performed to test for underlying mechanisms. Results: A 5 mu g/m3 increment in PM2.5 exposure was associated with-11.23 % (95 % CI:-17.36 % to-4.65 %, p = 0.0012) and-7.34 % (95 % CI:-11.56 % to-2.92 %, p = 0.0014) lower placental TL during the entire pregnancy and second trimester respectively, and with-12.96 % (95 % CI:-18.84 % to-6.64 %, p < 0.001) lower placental mtDNAc during the third trimester. Furthermore, PM2.5 exposure was associated with a 12.42 % (95 % CI:-1.07 % to 27.74 %, p = 0.059) higher cord plasma p53 protein level and a-3.69 % (95 % CI:-6.97 % to-0.31 %, p = 0.033) lower cord plasma PGC-1 alpha protein level during the third trimester. Placental TL mediated 65 % of the negative and 17 % of the positive association between PM2.5 and placental mtDNAc and cord plasma p53 protein levels, respectively.Conclusion: Ambient PM2.5 exposure during pregnancy is associated with markers of the core-axis of aging, with TL as a mediating factor. This study strengthens the hypothesis of the air pollution induced core-axis of aging, and may unravel a possible underlying mediating mechanism in an early-life epidemiological context. The authors thank all ENVIRONAGE participants, as well as the staff of the maternity ward, midwives, and the staff of the clinical laboratory of East-Limburg Hospital in Genk. The ENVIRONAGE birth cohort is supported by the Research Foundation, Belgium (Grant No. N1518119, No. G082317N and No. 1523817N), Kom Op Tegen Kanker (KOTK), and Methusalem. Dries S. Martens and Bram G. Janssen received a postdoctoral grant funded by the Research Foundation Flanders (12X9620N, and 12W3218N).

Background: Leukocyte telomere length shortening is a characteristic of premature senescence, a process that can be accelerated by oxidative stress. In general, patients with end-stage renal disease undergoing regular hemodialysis (HD) are repeatedly exposed to oxidative stress. Patients undergoing HD tend to have cardiovascular diseases associated with oxidative stress and inflammation. Therefore, we assumed that telomere length is associated with HD vintage and the degree of vascular calcification. Methods: A total of 144 patients undergoing regular HD before kidney transplantation and 62 patients on hemodialysis, but not undergoing kidney transplantation, were enrolled. We measured common laboratory values, such as calcium, phosphate, and hemoglobin levels, and assessed the degree of vascular calcification in the patients. The leukocyte telomere length was measured using reverse transcription polymerase chain reaction, and Spearman correlation was used for correlation analysis. Results: The leukocyte telomere length was negatively associated with age (rho = −0.306, P＜0.01); it was shorter in middle-aged patients than in young patients (13.48 ± 4.80 vs. 15.86 ± 4.51, P

Telomere length appears to correlate with survival in early non-small-cell lung cancer (NSCLC), but the prognostic impact of telomere status in advanced NSCLC remains undetermined. Our purpose was to evaluate telomere parameters as prognostic and predictive biomarkers in advanced NSCLC. In 79 biopsies obtained before treatment, we analyzed the telomere length and expression of TERT and shelterin complex genes (TRF1, TRF2, POT1, TPP1, RAP1, and TIN2), using quantitative PCR. Non-responders to first-line chemotherapy were characterized by shorter telomeres and low RAP1 expression (p = 0.0035 and p = 0.0069), and tended to show higher TERT levels (p = 0.058). In multivariate analysis, short telomeres were associated with reduced event-free (EFS, p = 0.0023) and overall survival (OS, p = 0.00041). TERT and TRF2 overexpression correlated with poor EFS (p = 0.0069 and p = 0.00041) and OS (p = 0.0051 and p = 0.007). Low RAP1 and TIN2 expression-levels were linked to reduced EFS (p = 0.00032 and p = 0.0069) and OS (p = 0.000051 and p = 0.02). Short telomeres were also associated with decreased survival after nivolumab therapy (p = 0.097). Evaluation of telomere status in advanced NSCLC emerges as a useful biomarker that allows for the selection of patient groups with different clinical evolutions, to establish personalized treatment.

BackgroundAccumulated senescent cells are proposed to be one of the main drivers of age-related pathology such as dementia and cancer through disruption of tissue structure and function. We recently proposed the Neuro-Immuno-Senescence Integrative Model (NISIM), which relates prefrontally modulated vagal tone and subsequent balance between vagal and sympathetic input to the spleen to inflammatory responses leading to generation of reactive oxygen species and oxidative telomere damage.AimIn this study, we assess inflammation as a mediator in the relationship between prefrontally modulated vagal tone and leukocyte telomere length (LTL). We also assess the relationship between a recently proposed index of vagal neuroimmunomodulation (vagal tone/inflammation ratio; NIM index) and telomere length.MethodsThis study uses participant data from a large nationally representative longitudinal study since 1974 with a total of 45,000 Norwegian residents so far. A sub-sample of 131 participants from which ultrashort recordings (30 s) of vagal tone, c reactive protein, and LTL could be obtained were included in the study. Relationships were analyzed with Pearson’s correlations and hierarchical multiple linear regression using either vagal tone and CRP or the NIM index to predict telomere length.ResultsVagal tone was a significant positive predictor of telomere length but this was not mediated by c reactive protein, even after controlling for confounders. The NIM index was a significant positive predictor of telomere length, also when controlling for confounders. In a follow-up analysis simultaneously comparing telomere length between groups with high and low values of vagal tone, and between groups with high and low NIM index values, telomere length was only significantly different between NIM index groups.ConclusionThis is the first study suggesting that prefrontally modulated vagal neuroimmunomodulation is associated with telomere length thus supporting the NISIM. Results indicate that the NIM index is a more sensitive indicator of vagal neuroimmunomodulation than vagal tone and CRP in isolation.

PURPOSE: Leukocyte telomere length (LTL) is a potential indicator of cellular senescence. However, its relationship with the type and volume of regular exercise is unclear. Therefore, we investigated the effects of the type and volume of long-term regular exercise on the LTL in middle-aged men (N=109, mean age=44.7±4.1 years [range: 40-56 years]).METHODS: For all participants, the volume of physical activity (PA) was evaluated using a self-report questionnaire, and blood samples were collected simultaneously. We cross-sectionally examined the associations among the type and volume of PA, LTL, telomerase activity (TA), mitochondrial DNA copy number (mtDNA), and body composition in three groups: 1) bodybuilders (BBs) with at least 5 years of athletic experience (n=36, mean age: 42.3±3.3 years [40-51 years]), 2) cyclists (CCs) with an athletic career similar to that of the BBs (n=37, mean age: 45.4±4.4 years [range: 40-53 years]), and 3) healthy ordinary people (CON; n=36, mean age: 46.3±3.3 years [range: 40-56 years]).RESULTS: The LTL showed a significant positive correlation with the volume of PA (r=.285, p=.003), regardless of the type of PA. Furthermore, the LTLs were longer in the BB (p=.007) and CC (p=.003) groups (who performed moderate-to-vigorous PA for 150 minutes or more per week) than in the CON group. Conversely, the TA was significantly higher in the BB group (p=.009) than in the CON group; however, it only tended to be high in the CC group (p=.115). There were no intergroup differences in both the mtDNA (p=.127) and 8-hydroxydeoxyguanosine (p=.289) levels.CONCLUSIONS: The TA was found to increase, and thus prevent telomere loss, in middle-aged men who performed PA of moderateto-vigorous intensity, regardless of the PA type.

Mesenchymal stem cells (MSCs) experience functional decline with systemic aging, resulting in reduced proliferation, increased senescence, and lower differentiation potential. The placenta represents a valuable source of MSCs, but the possible effect of donor age on the properties of placenta-derived mesenchymal stem cells (PDMSCs) has not been thoroughly studied. Thus, the aim of this study was to underscore the effect of maternal age on the biological characteristics and stemness properties of PDMSCs. PDMSCs were isolated from 5 donor age groups (A: 18-21, B: 22-25, C: 26-30, D:31-35 and E: ≥36 years) for comparison of morphological, proliferative and differentiation properties. The pluripotency markers NANOG, OCT4, and SSEA4, as well as multipotency and differentiation markers, showed higher expression in PDMSCs from mothers aged 22-35 years, with up to a 7-fold increase in adipogenesis. Cumulative population doubling, cell growth curves, and colony-forming unit-fibroblast assays revealed higher self-renewal ability in donors 26-30 years old. An increase in the proliferative characteristics of PDMSCs correlated with increased telomere shortening, suggesting that shorter telomere lengths could be related to cellular division rather than aging. A clear understanding of the effect of maternal age on MSC regenerative potential will assist in increasing the effectiveness of future cell therapies.

Aims/hypothesis Few large-scale prospective studies have investigated associations between relative leucocyte telomere length (rLTL) and kidney dysfunction in individuals with type 2 diabetes. We examined relationships between rLTL and incident end-stage kidney disease (ESKD) and the slope of eGFR decline in Chinese individuals with type 2 diabetes. Methods We studied 4085 Chinese individuals with type 2 diabetes observed between 1995 and 2007 in the Hong Kong Diabetes Register with stored baseline DNA and available follow-up data. rLTL was measured using quantitative PCR. ESKD was diagnosed based on the ICD-9 code and eGFR. Results In this cohort (mean ± SD age 54.3 ± 12.6 years) followed up for 14.1 ± 5.3 years, 564 individuals developed incident ESKD and had shorter rLTL at baseline (4.2 ± 1.2 vs 4.7 ± 1.2, p n = 3521). On Cox regression analysis, each ∆∆Ct decrease in rLTL was associated with an increased risk of incident ESKD (HR 1.21 [95% CI 1.13, 1.30], p 1c, lipids, renal function and other risk factors (HR 1.11 [95% CI 1.03, 1.19], p = 0.007). Shorter rLTL at baseline was associated with rapid decline in eGFR (>4% per year) during follow-up (unadjusted OR 1.22 [95% CI 1.15, 1.30], p p = 0.024). Conclusions/interpretation rLTL is independently associated with incident ESKD and rapid eGFR loss in individuals with type 2 diabetes. Telomere length may be a useful biomarker for the progression of kidney function and ESKD in type 2 diabetes. Graphical abstract

Background Telomere maintenance is increasingly recognized as being fundamental to glioma oncogenesis with longer leukocyte telomere length (LTL) reported to increase risk of glioma. To gain further insight into the relationship between telomere genetics and risk of glioma, we conducted several complementary analyses, using genome-wide association studies data on LTL (78 592 individuals) and glioma (12 488 cases and 18 169 controls). Methods We performed both classical and summary Mendelian randomization (SMR), coupled with heterogeneity in dependent instruments tests, at genome-wide significant LTL loci to examine if an association was mediated by the same causal variant in glioma. To prioritize genes underscoring glioma-LTL associations, we analyzed gene expression and DNA methylation data. Results Genetically increased LTL was significantly associated with increased glioma risk, random-effects inverse variance weighted ORs per 1 SD unit increase in the putative risk factor (odds ratio [OR]SD) 4.79 (95% confidence interval: 2.11-10.85; P = 1.76 × 10−4). SMR confirmed the previously reported LTL associations at 3q26.2 (TERC; PSMR = 1.33 × 10−5), 5p15.33 (TERT; PSMR = 9.80 × 10−27), 10q24.33 (STN1 alias OBFC1; PSMR = 4.31 × 10−5), and 20q13.3 (STMN3/RTEL1; PSMR = 2.47 × 10−4) glioma risk loci. Our analysis implicates variation at 1q42.12 (PSMR = 1.55 × 10−2), 6p21.3 (PSMR = 9.76 × 10−3), 6p22.2 (PSMR = 5.45 × 10−3), 7q31.33 (PSMR = 6.52 × 10−3), and 11q22.3 (PSMR = 8.89 × 10−4) as risk factors for glioma risk. While complicated by patterns of linkage disequilibrium, genetic variation involving PARP1, PRRC2A, CARMIL1, POT1, and ATM-NPAT1 was implicated in the etiology of glioma. Conclusions These observations extend the role of telomere-related genes in the development of glioma.

Telomere length (TL) is associated with biological aging, consequently influencing the risk of age-related diseases such as Alzheimer’s disease (AD). We aimed to evaluate the potential causal role of TL in AD endophenotypes (i.e., cognitive performance, N = 2233; brain age and AD-related signatures, N = 1134; and cerebrospinal fluid biomarkers (CSF) of AD and neurodegeneration, N = 304) through a Mendelian randomization (MR) analysis. Our analysis was conducted in the context of the ALFA (ALzheimer and FAmilies) study, a population of cognitively healthy individuals at risk of AD. A total of 20 single nucleotide polymorphisms associated with TL were used to determine the effect of TL on AD endophenotypes. Analyses were adjusted by age, sex, and years of education. Stratified analyses by APOE-ɛ4 status and polygenic risk score of AD were conducted. MR analysis revealed significant associations between genetically predicted longer TL and lower levels of CSF Aβ and higher levels of CSF NfL only in APOE-ɛ4 non-carriers. Moreover, inheriting longer TL was associated with greater cortical thickness in age and AD-related brain signatures and lower levels of CSF p-tau among individuals at a high genetic predisposition to AD. Further observational analyses are warranted to better understand these associations., The project leading to these results has received funding from the Alzheimer’s Association (Grant AARG-19-618265). This project has received funding from Instituto de Salud Carlos III (PI19/00119). Additional support has been received from “la Caixa” Foundation (ID 100010434), under agreement LCF/PR/GN17/50300004, the Alzheimer’s Association and an international anonymous charity foundation through the TriBEKa Imaging Platform project (TriBEKa-17-519007), the Health Department of the Catalan Government (Health Research and Innovation Strategic Plan (PERIS) 2016-2020 grant# SLT002/16/00201), and the Universities and Research Secretariat, Ministry of Business and Knowledge of the Catalan Government under the grant no. 2017-SGR-892. All CRG authors acknowledge the support of the Spanish Ministry of Science, Innovation and Universities to the EMBL partnership, the Centro de Excelencia Severo Ochoa, and the CERCA Programme/Generalitat de Catalunya. NV-T is funded by a post-doctoral grant, Juan de la Cierva Incorporación Programme (IJC2020-043216-I), Ministry of Science and Innovation–Spanish State Research Agency. EMAU is supported by the Spanish Ministry of Science, Innovation and Universities - Spanish State Research Agency (RYC2018-026053-I). MS-C receives funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement no. 948677). MS-C also receives funding from the Instituto de Salud Carlos III (PI19/00155) and from the Spanish Ministry of Science, Innovation and Universities (Juan de la Cierva Programme grant IJC2018-037478-I). HZ is a Wallenberg Scholar supported by grants from the Swedish Research Council (#2018-02532); the European Research Council (#681712); Swedish State Support for Clinical Research (#ALFGBG-720931); the Alzheimer Drug Discovery Foundation (ADDF), USA (#201809-2016862); the AD Strategic Fund and the Alzheimer’s Association (#ADSF-21-831376-C, #ADSF-21-831381-C, and #ADSF-21-831377-C); the Olav Thon Foundation; the Erling-Persson Family Foundation, Stiftelsen för Gamla Tjänarinnor, Hjärnfonden, Sweden (#FO2019-0228); the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 860197 (MIRIADE); and the UK Dementia Research Institute at UCL. KB is supported by the Swedish Research Council (#2017-00915); the Alzheimer Drug Discovery Foundation (ADDF), USA (#RDAPB-201809-2016615); the Swedish Alzheimer Foundation (#AF-742881); Hjärnfonden, Sweden (#FO2017-0243); the Swedish state under the agreement between the Swedish government and the County Councils, the ALF-agreement (#ALFGBG-715986); the European Union Joint Program for Neurodegenerative Disorders (JPND2019-466-236); and the National Institute of Health (NIH), USA, (grant #1R01AG068398-01). JDG is supported by the Spanish Ministry of Science and Innovation (RYC-2013-13054). AS-V. is the recipient of an Instituto de Salud Carlos III Miguel Servet II fellowship (CP II 17/00029).

This study investigated the associations between relative telomere length (RTL) and resting metabolic rate (RMR), resting fat oxidation (RFO), and aerobic capacity and whether oxidative stress and inflammation are the underlying mechanisms in sedentary women. We also aimed to determine whether the correlations depend on age and obesity. Sixty-eight normal weight and 66 obese women participated in this study. After adjustment for age, energy expenditure, energy intake, and education level, the RTL of all participants was negatively correlated with absolute RMR (RMRAB) and serum high-sensitivity C-reactive protein (hsCRP) concentration, and positively correlated with maximum oxygen consumption (V˙O2max) (all p < 0.05). After additional adjustment for adiposity indices and fat-free mass (FFM), RTL was positively correlated with plasma vitamin C concentration (p < 0.05). Furthermore, after adjustment for fasting blood glucose concentration, RTL was negatively correlated with age and positively correlated with V˙O2max (mL/kg FFM/min). We found that normal weight women had longer RTL than obese women (p < 0.001). We suggest that RTL is negatively correlated with RMRAB and positively correlated with aerobic capacity, possibly via antioxidant and anti-inflammatory mechanisms. Furthermore, age and obesity influenced the associations. We provide useful information for the management of promotion strategies for health-related physical fitness in women.

The beauty industry is actively searching for solutions to prevent skin aging. Some of the crucial elements protecting cells from the aging process are telomere shortening, telomerase expression, cell senescence, and homeostasis of the redox system. Modification of these factors using natural antioxidants is an appealing way to support healthy skin aging. Therefore, in this study, we sought to investigate the antiaging efficacy of a specific combination of four botanical extracts (pomegranate, sweet orange, Cistanche and Centella asiatica) with proven antioxidant properties. To this end, normal human dermal fibroblasts were used as a cell model and the following studies were performed: cell proliferation was established by means of the MTT assay and the intracellular ROS levels in stress-induced premature senescence fibroblasts; telomere length measurement was performed under standard cell culture conditions using qPCR and under oxidative stress conditions using a variation of the Q-FISH technique; telomerase activity was examined by means of Q-TRAP; and AGE quantification was completed by means of ELISA assay in UV-irradiated fibroblasts. As a result, the botanical blend significantly reversed the H2O2-induced decrease in cell viability and reduced H2O2-induced ROS. Additionally, the presence of the botanical ingredient reduced the telomere shortening rate in both stressed and non-stressed replicating fibroblasts, and under oxidative stress conditions, the fibroblasts presented a higher median and 20th percentile telomere length, as well as a lower percentage of short telomeres (

Background Studies often evaluate mental health and well-being in association with individual health behaviours although evaluating multiple health behaviours that co-occur in real life may reveal important insights into the overall association. Also, the underlying pathways of how lifestyle might affect our health are still under debate. Here, we studied the mediation of different health behaviours or lifestyle factors on mental health and its effect on core markers of ageing: telomere length (TL) and mitochondrial DNA content (mtDNAc). Methods In this study, 6054 adults from the 2018 Belgian Health Interview Survey (BHIS) were included. Mental health and well-being outcomes included psychological and severe psychological distress, vitality, life satisfaction, self-perceived health, depressive and generalised anxiety disorder and suicidal ideation. A lifestyle score integrating diet, physical activity, smoking status, alcohol consumption and BMI was created and validated. On a subset of 739 participants, leucocyte TL and mtDNAc were assessed using qPCR. Generalised linear mixed models were used while adjusting for a priori chosen covariates. Results The average age (SD) of the study population was 49.9 (17.5) years, and 48.8% were men. A one-point increment in the lifestyle score was associated with lower odds (ranging from 0.56 to 0.74) for all studied mental health outcomes and with a 1.74% (95% CI: 0.11, 3.40%) longer TL and 4.07% (95% CI: 2.01, 6.17%) higher mtDNAc. Psychological distress and suicidal ideation were associated with a lower mtDNAc of − 4.62% (95% CI: − 8.85, − 0.20%) and − 7.83% (95% CI: − 14.77, − 0.34%), respectively. No associations were found between mental health and TL. Conclusions In this large-scale study, we showed the positive association between a healthy lifestyle and both biological ageing and different dimensions of mental health and well-being. We also indicated that living a healthy lifestyle contributes to more favourable biological ageing.

Diffuse gliomas encompass a diverse group of tumors of the central nervous system that primarily affect the brain. Patients suffer from a poor prognosis despite radical treatment with surgery, radio- and chemotherapy. Microscopic evaluation by a neuropathologist has been the established method for the clinical diagnosis and determination of follow-up for over a century. Nevertheless, pathology assessment suffers from sampling biases and interobserver variability. This thesis details a number of studies that focus on the molecular analysis of this tumor type. They are a part of a larger series of papers in the past decade that demonstrate that molecular diagnostics can provide an unambiguous diagnosis and determination of follow-up treatment.

Biological aging is an umbrella term that refers to a complex biological process which entails the aging of cells, their organelles and DNA (Hägg & Jylhävä, 2021). Biological aging processes have been associated with a variety of diseases, including cancer and atherosclerosis (Adams & White, 2004; Dugué et al., 2018), and are a good predictor for higher morbidity and mortality rates (Perna et al., 2016). Therefore, a growing body of research is focused on potential factors affecting biological aging. Biological aging can be operationalized by different biomarkers, including telomere length and epigenetic clocks (Belsky et al., 2018; Pearce et al., 2022). Telomeres are repetitive TTAGGG sequences at the end of chromosomes that protect the chromosomes from shortening during cell division. Telomeres shorten throughout the lifespan, and accelerated telomere shortening is an index of accelerated biological aging (Tempaku et al., 2015; Vaiserman & Krasnienkov, 2021). Furthermore, the epigenetic clock concerns DNA methylation levels, namely the accumulation of methyl groups to DNA molecules, and is an estimator of chronical age (Chen et al., 2016; Jylhävä et al., 2017). These clocks capture methylation of certain sets of CpG sites in the DNA, and methylation levels correlate with age. Accordingly, the biological age of the cells can be calculated in years (Chen et al., 2016; Horvath et al., 2012; McEwen et al., 2020). It has been found that, besides genetic factors (Gibson et al., 2019), also environmental factors, such as smoking and diet, are associated with both of the previous biomarkers of accelerated biological aging (Gao et al., 2016; Horvath et al., 2014; Huang et al., 2019; Vaiserman & Krasnienkov, 2021). Accelerated biological aging in terms of accelerated telomere attrition and advanced epigenetic age has also been associated with sleeping problems in adults (Carskadon et al., 2019; Carroll & Prather, 2021; Cribbet et al., 2014; Gao et al., 2022; James et al., 2017; Jin et al., 2022). Sleep is a complex behavioral and homeostatically regulated state of all mammals (Zielinski et al., 2016). Sleep has many vital functions, including development, modulation of immune responses, memory consolidation and endocrine functions (Krueger et al., 2016; Zielinski et al., 2016). Previous research has demonstrated associations between poor quality of sleep, shorter sleep duration, and delayed sleep onset with shortened telomere lengths (Cribbet et al., 2014; Wynchank et al., 2019). Additionally, reduced sleep duration and poor sleep quality have also been linked to the acceleration of the epigenetic clock (Carskadon et al., 2019; Gao et al., 2022) This association between sleep and accelerated biological aging was not only observed in adults. James and colleagues (2017) found an association of shorter telomeres with shorter sleep durations in nine-year-old children, indicating that the relationship between biological aging and sleep already emerges early in development (James et al., 2017). However, to our knowledge, this is the only study that has looked at children’s sleep in relation to markers for biological aging. Therefore, to date, there is a lack of research on the association of sleep quality with biological aging in children. Additionally, the previously mentioned study on this association in children was cross-sectional, hence the directionality of the relationship between biological aging and sleep quality in children remains unclear. On the one hand, previous studies in adults have largely assumed that more sleeping problems cause alterations in neuro-chemical processes, which, in turn, cause accelerated aging. But on the other hand, studies on the elderly population suggest that accelerated aging can cause significant alterations in the sleep stages and in the quantity and quality of sleep (Tempaku et al., 2015), indicating that aging could also bring about sleep changes. Accordingly, Carrol and Prather (2021) suggest that there is also a possibility that accelerated biological aging causes alterations in brain areas that regulate sleep states, hereby causing sleep difficulties (Carroll & Prather, 2021). Since previous research on the association of sleep and biological aging in children was solely cross-sectional, the directionality of the association remains to be assessed. In the current study we assess the association of sleep with accelerated biological aging in children bi-directionally between chronological ages 6 years (T1) and 10 years (T2). As telomere length and epigenetic clocks have been shown to capture different biological aging processes (Belsky et al., 2018; Pearce et al., 2022), both will be used in this study to measure biological aging. In previous studies, the Pediatric-Buccal-Epigenetic (PedBE) clock has been reported to be the most reliable epigenetic clock for pediatrics (McEwen et al., 2020), and will hence be used in the current study. In this study, we will assess the following goals: 1) Our first goal is to assess cross-sectional associations at T1 and T2 between our biomarkers of biological aging (telomere length and PedBE clock) with child sleeping problems. 2) Our second goal is to determine whether sleeping problems at T1 forecasts biological aging, defined as a) telomere length at T2; b) telomere erosion between T1 – and T2; c) PedBE clock at T2. 3) Our third goal is to determine whether our biomarkers of biological aging (a, b & c) predict sleeping problems at T2. a) telomere length; b) telomere erosion from T1 to T2; c) PedBE clock at T1. 4) Lastly, we will assess the directionality between sleeping problems and biological aging by comparing the explained variance between question 2 and 3. Note that we do not include the change in PedBE from T1 to T2, as the PedBE clock already incorporates the difference between biological aging and chronological aging as an age acceleration. Given that telomere length and/or erosion varies by sex (Barrett & Richardson, 2011), z-score body mass index index (zBMI; Clemente et al., 2019; Gielen et al., 2018), and maternal education (Broer et al., 2013), we will statistically control for these aspects in our analyses. This will be done by using child sex determined at birth, child zBMI at T2 and maternal education defined as the highest level of education completed when assessed at T2 (Beijers, Hartman, et al., 2020; Shalev et al., 2013).

Diffuse gliomas encompass a diverse group of tumors of the central nervous system that primarily affect the brain. Patients suffer from a poor prognosis despite radical treatment with surgery, radio- and chemotherapy. Microscopic evaluation by a neuropathologist has been the established method for the clinical diagnosis and determination of follow-up for over a century. Nevertheless, pathology assessment suffers from sampling biases and interobserver variability. This thesis details a number of studies that focus on the molecular analysis of this tumor type. They are a part of a larger series of papers in the past decade that demonstrate that molecular diagnostics can provide an unambiguous diagnosis and determination of follow-up treatment.

Hutchinson–Gilford progeria syndrome (HGPS) is a rare premature aging syndrome caused by a dominant mutation in the LMNA gene. Previous research has shown that the ectopic expression of the catalytic subunit of telomerase (hTERT) can elongate the telomeres of the patients’ fibroblasts. Here, we established five immortalized HGP fibroblast cell lines using retroviral infection with the catalytic subunit of hTERT. Immortalization enhanced the proliferative life span by at least 50 population doublings (PDs). The number of cells with typical senescence signs was reduced by 63 + 17%. Furthermore, the growth increase and phenotype improvement occurred with a lag phase of 50–100 days and was not dependent on the degree of telomere elongation. The initial telomeric stabilization after hTERT infection and relatively low amounts of hTERT mRNA were sufficient for the phenotype improvement but the retroviral infection procedure was associated with transient cell stress. Our data have implications for therapeutic strategies in HGP and other premature aging syndromes.

Finding new strategies for the treatment of heart failures using stem cells has attracted a lot of attention. Meanwhile, nanotechnology-based approaches to regenerative medicine hypothesize a possible combination of stem cells and nanotechnology in the treatment of diseases. This study aims to investigate the in vitro effect of silver nanoparticles (Ag-NPs) on the cardiomyogenic differentiation of bone marrow-derived mesenchymal stem cells (BM-MSCs) through detection of cardiac markers. For this purpose, MSCs were isolated from bone marrow resident and differentiated to the cardiac cells using a dedicated medium with Ag-NPs. Also, the cardiomyogenic differentiation of BM-MSCs was confirmed using immunocytochemistry. Then, real-time PCR and western blotting assay were used for measuring absolute telomere length (TL) measurement, and gene and protein assessment of the cells, respectively. It was found that 2.5 µg/mL Ag-NPs caused elongation of the telomeres and altered VEGF, C-TnI, VWF, SMA, GATA-4, TERT, and cyclin D protein and gene expression in the cardiomyogenically differentiated BM-MSCs. Also, there was a significant increase in the protein and gene expression of Wnt3 and β-catenin as main components of pathways. We concluded that Ag-NPs could change the in vitro expression of cardiac markers of BM-MSCs via the Wnt3/β-catenin signaling pathway.

ContextChronic exposure to glucocorticoids (GCs) or stress increases the risk of medical disorders, including cardiovascular and neuropsychiatric disorders. GCs contribute to accelerated aging; however, while the link between chronic GC exposure and disease onset is well established, the underpinning mechanisms are not clear.ObjectiveWe explored the potential nexus between GCs or stress exposure and telomere length.MethodsIn addition to rats exposed to 3 weeks of chronic stress, an iatrogenic mouse model of Cushing syndrome (CS), and a mouse neuronal cell line, we studied 32 patients with CS and age-matched controls and another cohort of 75 healthy humans.Results(1) Exposure to stress in rats was associated with a 54.5% (P = 0.036) reduction in telomere length in T cells. Genomic DNA (gDNA) extracted from the dentate gyrus of stressed and unstressed rats showed 43.2% reduction in telomere length (P = 0.006). (2) Mice exposed to corticosterone had a 61.4% reduction in telomere length in blood gDNA (P = 5.75 × 10-5) and 58.8% reduction in telomere length in the dentate gyrus (P = 0.002). (3) We observed a 40.8% reduction in the telomere length in patients with active CS compared to healthy controls (P = 0.006). There was a 17.8% reduction in telomere length in cured CS patients, which was not different from that of healthy controls (P = 0.08). For both cured and active CS, telomere length correlated significantly with duration of hypercortisolism (R2 = 0.22, P = 0.007). (4) There was a 27.6% reduction in telomere length between low and high tertiles in bedtime cortisol levels of healthy participants (P = 0.019).ConclusionOur findings demonstrate that exposure to stress and/or GCs is associated with shortened telomeres, which may be partially reversible.

Background: Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory disease with increased prevalence in the elderly. Telomeres are repetitive DNA sequences found at the end of the chromosome, which progressively shorten as cells divide. Telomere length is known to be a molecular marker of aging. This study aimed to assess the relationship between telomere length and the risk of COPD, lung function, respiratory symptoms, and emphysema index in Chronic Obstructive Pulmonary Disease in Dusty Areas (CODA) cohort. Methods: We extracted DNA from the peripheral blood samples of 446 participants, including 285 COPD patients and 161 control participants. We measured absolute telomere length using quantitative real-time polymerase chain reaction. All participants underwent spirometry and quantitative computed tomography scan. Questionnaires assessing respiratory symptoms and the COPD Assessment Test was filled by all the participants. Results: The mean age of participants at the baseline visit was 72.5±7.1 years. Males accounted for 72% (321 participants) of the all participants. The mean telomere length was lower in the COPD group compared to the non-COPD group (COPD, 16.81±13.90 kb; non-COPD, 21.97±14.43 kb). In COPD patients, 112 (75.7%) were distributed as tertile 1 (shortest), 91 (61.1%) as tertile 2 and 82 (55%) as tertile 3 (longest). We did not find significant associations between telomere length and lung function, exacerbation, airway wall thickness, and emphysema index after adjusting for sex, age, and smoking status. Conclusion: In this study, the relationship between various COPD phenotypes and telomere length was analyzed, but no significant statistical associations were shown.

Telomere length (TL) and telomere shortening are biological indicators of aging, and epigenetic associates have been found for TL in adults. However, the role of epigenetic signatures in setting newborn TL and early life telomere dynamics is unknown. In the present study, based on 247 participating newborns from the ENVIRONAGE birth cohort, whole-genome DNA methylation, profiled on the Illumina MethylationEPIC BeadChip microarray, and TL were measured in cord blood. In a follow-up visit at a mean age of 4.58 years, leukocyte TL was evaluated. We combined an epigenome-wide association study and a statistical learning method with re-sampling to select CpGs and their two-way interactions to model baseline (cord blood) TL and early-life telomere attrition rate, where distinct epigenetic signatures were identified for the two outcomes. In addition, a stronger epigenetic regulation was suggested in setting newborn TL than that of telomere dynamics in early life: 47 CpGs and 7 between-CpG interactions explained 76% of the variance in baseline TLs, while 72% of the total variance in telomere attrition rate was explained by 31 CpGs and 5 interactions. Functional enrichment analysis based on the selected CpGs in the two models revealed GLUT4 translocation and immune cell signaling pathways, respectively. These CpGs and interactions, as well as the cellular pathways, are potential novel targets of further investigation of telomere biology and aging. Funding The ENVIRONAGE birth cohort is supported by grants from the European Research Council (Grant No. ERC-2012-StG310898), the Flemish Scientific Fund (FWO, Grant No. G073315N) and Kom Op Tegen Kanker DSM (FWO grant 12X9620N) is postdoctoral fellows of the Flanders Research Foundation. SL is the beneficiary of a post-doctoral fellowship (12L5216N) provided by The Research Foundation-Flanders (FWO) and the Flemish Institute of Technological Research (VITO). Acknowledgments We acknowledge the cohort participants, midwives, the staff of the maternity ward and the clinical laboratory of East-Limburg Hospital in Genk.

Telomere length (TL) is a marker of biological aging associated with several health outcomes. High throughput reproducible TL measurements are needed for large epidemiological studies. We compared the novel DNA methylation-based estimator (DNAmTL) with the high-throughput quantitative PCR (qPCR) and the highly accurate flow cytometry with fluorescent in situ hybridization (flow FISH) methods using blood samples from healthy adults. We used Pearson’s correlation coefficient, Bland Altman plots and linear regression models for statistical analysis. Shorter DNAmTL was associated with older age, male sex, white race, and cytomegalovirus seropositivity (p70% of TL categorized above or below the median, but the accuracy dropped with increasing TL categories. The ability of DNAmTL to detect associations with age and other TL-related factors in the absence of strong correlation with measured TL may indicate its capture of aspects of telomere maintenance mechanisms and not necessarily TL. The inaccuracy of DNAmTL prediction should be considered during data interpretation and across-study comparisons.

This study will investigate how four measures of physiological weathering (allostatic load, biological age, epigenetic age, and telomere length) relate over time in the Lothian Birth Cohort 1936.

This study investigates variation in biological embedding of stress among Syrian refugee children living in tented settlements in the Beqaa region of Lebanon. The data are drawn from the Biological Pathways of Risk and Resilience in Syrian Refugee Children (BIOPATH) funded by the Eunice Kennedy Shriver National Institute of Child Health & Human Development (R01HD083387). Research activities are supported by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 896988 and the Telomere Research Network (NIH U24 AG066528-03, PI: Stacy Drury). Saliva samples from 1,368 Syrian refugee children collected at Wave 1 will undergo telomere length assessment by qPCR resulting in measures of absolute telomere length, average telomere length, and T/S ratio. Telomere length will be evaluated in a moderated mediation model where telomere length mediates relations between war exposure and mental health outcomes (depression and PTSD symptoms), and environmental sensitivity moderates the relationship between war exposure and telomere length. We will also investigate associations between telomere length and pubertal development in boys and girls separately. Specifically, we will investigate if telomere length mediates the relations between war exposure and pubertal development.

The objective of the proposed study is to compare several proposed indices of biological aging, building on our published analyses 1,2. We will analyze data from 1999-2000 and 2001-2002 waves of the National Health and Nutrition Examination Survey. We will analyze three types of data to measure biological aging: (1) blood chemistry, complete blood count, and organ-function test data; (2) leukocyte telomere length data; and (3) DNA methylation data. We will test associations of measures of biological aging with chronological age and with measures of functional performance, chronic disease morbidity, and mortality, as well as with indicators of social determinants of health. Non-genomic data will be used to compose four indices of biological aging based on the methods proposed by Levine (blood-chemistry PhenoAge) 3,4, Klemera and Doubal (KDM Biological Age) 5, Cohen and colleagues (homeostatic dysregulation) 6, and the Allostatic Load (AL) approach developed by Seemans and colleagues 7. Whole genome DNA methylation data will be used to construct seven measures of biological aging: the DNA methylation clocks proposed by Horvath 8, Hannum 9, Lu et al. (GrimAge)10, and Levine et al. (PhenoAge)4, the Pace of Aging measures proposed by Belsky et al. 11 (DunedinPoAm, DunedinPACE), and a DNA methylation based estimator of telomere length proposed by Lu et al. (DNAmTL) 12.

The present study involves comparing two different approaches toward the measurement of telomere length in a cohort of children from an NICHD sponsored P50 study (P50HD089922) into the etiology and biopsychosocial consequences of maltreatment. A subset of children will undergo telomere length assessment by qPCR to generate measures of absolute telomere length (aTL) and T/S ratio. Whole genome methylation data will also be used to construct a DNA methylation based estimator of telomere length (DNAmTL). The associations between telomere length estimations generated via qPCR and DNA methylation and measures of external validity will be compared to assess their relative utility as proxies of biological age in a child/adolescent cohort. Furthermore, the role of maltreatment, biological sex, and race/ethnicity as moderators of these associations and differences will be explored.