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Abstract Telomere length (TL) is a marker of biological aging, and shorter telomeres have been associated with several medical and psychiatric disorders, including cardiometabolic dysregulation and Major Depressive Disorder (MDD). In addition, studies have shown shorter TL to be associated with poorer response to certain psychotropic medications, and our previous work suggested shorter TL and higher telomerase activity (TA) predicts poorer response to Selective Serotonin Reuptake Inhibitor (SSRI) treatment. Using a new group of unmedicated medically healthy individuals with MDD (n = 48), we sought to replicate our prior findings demonstrating that peripheral blood mononuclear cell (PBMC) TL and TA predict response to SSRI treatment and to identify associations between TL and TA with biological stress mediators and cardiometabolic risk indices. Our results demonstrate that longer pre-treatment TL was associated with better response to SSRI treatment (β = .407 p = .007). Additionally, we observed that TL had a negative relationship with allostatic load (β = − .320 p = .017) and a cardiometabolic risk score (β = − .300 p = .025). Our results suggest that PBMC TL reflects, in part, the cumulative effects of physiological stress and cardiovascular risk in MDD and may be a biomarker for predicting SSRI response.

Chromatin dynamics is thought to play an important role in the maintenance of telomeres, yet how has remained poorly understood. Here the authors locally enrich heterochromatin protein 1α (HP1α) at human telomeres to provide insights into the crosstalk between epigenetic regulations and structural dynamics at the telomeres.

Telomeres, the protective DNA-protein complexes at the ends of linear chromosomes, are important for genome stability. Leukocyte or peripheral blood mononuclear cell (PBMC) telomere length is a potential biomarker for human aging that integrates genetic, environmental, and lifestyle factors and is associated with mortality and risks for major diseases. However, only a limited number of studies have examined longitudinal changes of telomere length and few have reported data on sorted circulating immune cells. We examined the average telomere length (TL) in CD4+, CD8+CD28+, and CD8+CD28− T cells, B cells, and PBMCs, cross-sectionally and longitudinally, in a cohort of premenopausal women. We report that TL changes over 18 months were correlated among these three T cell types within the same participant. Additionally, PBMC TL change was also correlated with those of all three T cell types, and B cells. The rate of shortening for B cells was significantly greater than for the three T cell types. CD8+CD28− cells, despite having the shortest TL, showed significantly more rapid attrition when compared to CD8+CD28+ T cells. These results suggest systematically coordinated, yet cell type-specific responses to factors and pathways contribute to telomere length regulation.

Background. Accumulating evidence supports leukocyte telomere length (LTL) as a biological marker of cellular aging. Poor sleep is a risk factor for age-related disease; however, the extent to which sleep accounts for variation in LTL is unknown. Methods. The present study examined associations of self-reported sleep duration, onset latency, and subjective quality with LTL in a community-dwelling sample of 245 healthy women in midlife (aged 49–66 years). Results. While sleep duration and onset latency were unrelated to LTL, women reporting poorer sleep quality displayed shorter LTL (r=0.14, P=0.03), independent of age, BMI, race, and income (b=55.48, SE=27.43, P=0.04). When analyses were restricted to participants for whom sleep patterns were chronic, poorer sleep quality predicted shorter LTL independent of covariates and perceived psychological stress. Conclusions. This study provides the first evidence that poor sleep quality explains significant variation in LTL, a marker of cellular aging.

Rationale : Chronic stress has been related to lower telomerase, an enzyme that helps preserve the integrity of DNA and slow immunological aging. However, it is unknown whether daily psychological processes reflecting healthy emotion regulation protect against stress-related immune-aging. Methods : We examined basal telomerase activity in a sample of 72 healthy premenopausal women across a range of stress levels, including 35 mothers caring for a child with autism and 37 low-stress control mothers of healthy children. Participants completed a nightly diary over the course of a week, reporting their exposure to positive and negative events. Then they rated the extent to which they employed various emotion-regulation strategies in response to these events. Within-subject weekly means for all measures were calculated. In addition, composite scores for positive affect in response to positive daily events and negative affect in response to daily stressors were calculated, and weekly means obtained. Depressive symptoms were assessed using the Inventory of Depressive Symptoms. On day 4 of the study week, a fasting blood draw was performed to measure peripheral blood mononuclear cells (PBMC) telomerase activity. Results : Higher telomerase activity was significantly associated with the use of more resilient emotion regulation strategies, including more positive emotional responses to positive daily events (r=0.27, p=0.02) and increased savoring of positive daily events (r=0.24, p=0.04). In general, negative emotional responses and rumination in response to daily stressors were not related to telomerase with two exceptions: lower telomerase was associated with greater emotional suppression (r= − 0.34, p

Telomere length (TL) is an important marker of cellular aging that can be examined from birth to death and provide information about health status and disease risk. TL shortens in early childhood with the majority of the shortening occurring by age 4. TL is associated with stress and obesity in adults. It is possible that exposure to early life stressors and excess adiposity from birth and the first year of life may impact the rate of telomere shortening. Few studies have examined TL in the first years of life, and none of them have examined stress and obesity in infants.We examined TL by qPCR using genomic DNA from dried blood spots in a sample of 109 four-year-old, low-income Latino children and their mothers. TL is expressed as T/S (the ratio of telomeric product vs. single copy gene product). This group of children and their mothers were recruited prenatally in San Francisco at which time socio-demographic and health history was assessed. In addition, child weight and length and maternal body mass index (BMI) have been assessed annually from birth with the child's weight and length measured also at birth and 6 months of age. Maternal depressive symptoms were assessed prenatally, at 4–6 weeks postpartum and annually throughout the follow-up period. Child behavior was evaluated using the child behavior checklist (CBCL) at 3 and 4 years of age for internalizing and externalizing behaviors. Student's t-tests were performed to compare TL in relationship to different childhood exposures – maternal depression, child overweight and obesity, and socio-demographic factors such as child sex, ethnicity, and socioeconomic status. Factors that were significant at p

Rationale/statement of the problem : Major depressive disorder (MDD) and other serious mental illnesses are associated with high rates of comorbid medical illnesses. Many of these comorbid conditions are more typically seen in the aged, raising the possibility that these psychiatric illnesses are associated with accelerated aging. An emerging biomarker of cell aging and of increased risk of medical illness is leukocyte telomere length, and several studies have now characterized leukocyte telomere length in MDD and other psychiatric illnesses. Fewer psychiatric studies have characterized the activity of telomerase, an enzyme that can elongate and preserve telomeric DNA, or have investigated the biochemical mediators of accelerated telomere shortening. Methods : Seven studies examining telomere length in MDD, three studies in schizophrenia, two studies in bipolar illness, two studies in PTSD, and one study in generalized anxiety disorder were reviewed, as were one study of telomerase activity in MDD and one study in schizophrenia. Additional studies in chronically stressed individuals and in individuals with histories of childhood adversity were also reviewed. Results : Shortened leukocyte telomeres have been demonstrated in MDD, bipolar illness, schizophrenia, anxiety disorders, and post-traumatic stress disorder, although in some studies, only subgroups of patients (e.g., those with longer lifetime exposure to the illness, those with poor responses to treatment, or those with preexisting histories of childhood adversity) showed shortened telomeres. Leukocyte telomere shortening is correlated with peripheral indices of increased oxidative stress and increased immune activation. Two studies (one in caregivers with high depression ratings and one in unmedicated patients with MDD) reported elevated peripheral blood mononuclear cell (PBMC) telomerase activity, perhaps representing a compensatory attempt by the body to preserve endangered telomeres. Preliminary data in MDD suggest that relatively low telomerase activity before treatment, and greater treatment-associated increases in telomerase activity, are associated with better antidepressant responses. This, plus the preliminary observation that PBMC telomerase activity is directly correlated with hippocampal volume (by MRI) in MDD, support emerging preclinical data that telomerase has intrinsic neurotrophic and antidepressant effects. Conclusion : Telomere shortening in MDD and certain other psychiatric conditions may, at least partially, reflect chronic exposure to inflammation and oxidation. As such, it may be a bellwether of increased medical risk, or it may play a more direct causal role in accelerated aging. The interplay of telomere integrity and telomerase activity may be an important determinant of psychiatric and medical outcome. Overall, the data are consistent with the view that MDD and certain other psychiatric illnesses have systemic manifestations beyond the brain and call into question the dichotomy of “mental” vs. “physical” illnesses.

Obesity and the metabolic syndrome (MetS) predispose to multiple diseases and to accelerated cell aging as indexed by accelerated shortening of telomeres in peripheral blood mononuclear cells (PBMC's). Major depressive disorder (MDD) is often associated with MetS and is also associated with increased disease risk and PBMC telomere shortening. A potential role of leptin in telomere shortening has been suggested, but prior results have been inconsistent and no study has yet assessed this relationship in MDD. The goal of this study was to assess the relationship between serum leptin concentrations and PBMC telomere length in MDD and in controls and to assess whether this relationship is mediated by body-mass index (BMI) or the homeostatic model assessment of insulin resistance (HOMA-IR), two principal components of the MetS.Eighteen medication-free MDD subjects (11 female, 7 male, mean age 37.1 + 2.7 years) and 17 healthy controls (11 female, 6 male, mean age 37.8 + 3.0 years) had blood drawn for assay of fasting morning levels of leptin, glucose, and insulin and PBMC telomere length. The groups did not differ on BMI (24.66 + 3.72 vs. 24.77 + 4.29, respectively, n.s.). Analyses were co-varied for age and sex, with and without BMI.In the combined group, serum leptin concentrations were inversely correlated with telomere length (r= − 0.33, p0.30, and t=1.49, p>0.10, respectively), but leptin concentrations remained significantly correlated with telomere length (t= − 2.88, p=0.007).Relatively high leptin concentrations, in the presence or absence of increased BMI and insulin resistance, may be a risk factor for telomere shortening. While this was demonstrated here in individuals with MDD, a similar relationship in non-depressed individuals cannot be ruled out because of the small sample size.

Rationale/statement of the problem : Substantial evidence suggests conditions in intrauterine life may play a critical role in subsequent health and disease susceptibility related outcomes (i.e., the concept of fetal or developmental programming of health and disease). The elucidation of biological mechanisms underlying these effects is an area of active investigation. We suggest that telomere biology may represent a novel mechanism underlying the effects of a disparate set of suboptimal intrauterine exposures on various health and disease risk phenotypes. From an evolutionary-developmental perspective, energy substrate availability (i.e., nutrition) and challenges that have the potential to impact the structural or functional integrity and survival of the organism (i.e., stress) likely represent the most important environmental considerations underlying natural selection and developmental plasticity. Maternal stress and nutrition in pregnancy therefore represent attractive candidate processes in the context of fetal programming of telomere biology. Our previous work has established an important role for prenatal stress and stress-related processes in adult telomere biology Methods : In two longitudinal birth cohorts, stress- and nutrition-related processes were assessed during pregnancy and telomere length (TL) was subsequently measured in newborns (cord blood) and infants (buccal cells). Results : (1) Among the nutrition-related factors, maternal lower folate levels (an essential methyl donor) and higher triglyceride concentrations in early pregnancy were significantly and independently associated with shorter newborn TL. (2) Among psychosocial stress-related measures, higher maternal pregnancy-specific stress was associated with shorter newborn TL. (3) Maternal estrogen (E3) levels during early pregnancy were associated with longer infant TL. Conclusion : Taken together, our findings provide the first evidence in humans that maternal nutrition and stress-related processes during pregnancy may exert a programming effect on the newborn and infant telomere biology system. In utero telomere biology represents a potential molecular mechanism whereby different exposures in this critical developmental period before birth could impact subsequent health and disease susceptibility related outcomes over the life span, including aging and longevity

The cellular enzyme elomerase replenishes telomeric DNA, which can be lost during repeated mitoses or during exposure to inflammation and oxidation. However, telomerase may have other, non-canonical functions, including (in animal models) antidepressant and neurogenesis-enhancing effects. In this study, we determined the relationship between telomerase activity [(measured in peripheral blood mononuclear cells (PBMCs)] and hippocampal (HC) volume in depressed individuals (MDDs) and matched controls.Nineteen medication-free subjects with MDD and 17 matched healthy controls underwent 4T MRI scanning and fasting morning venipuncture for assessment of unstimulated PBMC telomerase activity. Due to the exploratory nature of the study, corrections for multiple comparisons were not applied.Hippocampal volume was smaller, but not significantly so, in the MDDs than the controls. As reported previously, MDD subjects had significantly higher PBMC telomerase activity than the controls (p=0.007). Within the MDD group (but not in the control group or in the combined sample), PBMC telomerase activity was positively correlated with HC volume (r=0.49, p

Leukocyte telomere length (LTL) is a putative biological marker of immune system age, and there are demonstrated associations between LTL and cardiovascular disease. This may be due in part to the relationship of LTL with other biomarkers associated with cardiovascular disease risk. However, the strength of associations between LTL and adiposity, metabolic, proinflammatory, and cardiovascular biomarkers has not been systematically evaluated in a United States nationally representative population.We examined associations between LTL and 17 cardiovascular biomarkers, including lipoproteins, blood sugar, circulatory pressure, proinflammatory markers, kidney function, and adiposity measures, in adults ages 20 to 84 from the cross-sectional US nationally representative 1999-2002 National Health and Nutrition Examination Survey (NHANES) (n = 7,252), statistically adjusting for immune cell type distributions. We also examine whether these associations differed systematically by age, race/ethnicity, gender, education, and income. We found that a one unit difference in the following biomarkers were associated with kilobase pair differences in LTL: BMI -0.00478 (95% CI -0.00749--0.00206), waist circumference -0.00211 (95% CI -0.00325--0.000969), percentage of body fat -0.00516 (95% CI -0.00761--0.0027), high density lipoprotein (HDL) cholesterol 0.00179 (95% CI 0.000571-0.00301), triglycerides -0.000285 (95% CI -0.000555--0.0000158), pulse rate -0.00194 (95% CI -0.00317--0.000705), C-reactive protein -0.0363 (95% CI 0.0601--0.0124), cystatin C -0.0391 (95% CI -0.0772--0.00107). When using clinical cut-points we additionally found associations between LTL and insulin resistance -0.0412 (95% CI -0.0685--0.0139), systolic blood pressure 0.0455 (95% CI 0.00137-0.0897), and diastolic blood pressure -0.0674 (95% CI -0.126--0.00889). These associations were 10%-15% greater without controlling for leukocyte cell types. There were very few differences in the associations by age, race/ethnicity, gender, education, or income. Our findings are relevant to the relationships between these cardiovascular biomarkers in the general population but not to cardiovascular disease as a clinical outcome.LTL is most strongly associated with adiposity, but is also associated with biomarkers across several physiological systems. LTL may thus be a predictor of cardiovascular disease through its association with multiple risk factors that are physiologically correlated with risk for development of cardiovascular disease. Our results are consistent with LTL being a biomarker of cardiovascular aging through established physiological mechanisms.

[This corrects the article DOI: 10.1371/journal.pone.0160748.].

Short telomere length independently predicts mortality in patients with coronary heart disease. Whether 5-year change in telomere length predicts subsequent mortality in patients with coronary heart disease has not been evaluated.In a prospective cohort study of 608 individuals with stable coronary artery disease, we measured leukocyte telomere length at baseline and after five years of follow-up. We divided the sample into tertiles of telomere change: shortened, maintained or lengthened. We used Cox survival models to evaluate 5-year change in telomere length as a predictor of mortality.During an average of 4.2 years follow-up, there were 149 deaths. Change in telomere length was inversely predictive of all-cause mortality. Using the continuous variable of telomere length change, each standard deviation (325 base pair) greater increase in telomere length was associated with a 24% reduction in mortality (HR 0.76, 95% CI 0.61-0.94; p = 0.01), adjusted for age, sex, waist to hip ratio, exercise capacity, LV ejection fraction, serum creatinine, and year 5 telomere length. Mortality occurred in 39% (79/203) of patients who experienced telomere shortening, 22% (45/203) of patients whose telomere length was maintained, and 12% (25/202) of patients who experienced telomere lengthening (p

Apolipoprotein-ε4 (APOE-ε4) is a major genetic risk factor for cognitive decline, Alzheimer's disease (AD) and early mortality. An accelerated rate of biological aging could contribute to this increased risk. Here, we determined whether APOE-ε4 status impacts leukocyte telomere length (TL) and the rate of cellular senescence in healthy mid-life women and, further, whether hormone replacement therapy (HT) modifies this association. Post-menopausal women (N = 63, Mean age = 57.7), all HT users for at least one year, were enrolled in a randomized longitudinal study. Half of the participants (N = 32) remained on their HT regimen and half (N = 31) went off HT for approximately two years (Mean = 1.93 years). Participants included 24 APOE-ε4 carriers and 39 non-carrier controls. Leukocyte TL was measured at baseline and the end of year 2 using quantitative polymerase chain reaction. Logistic regression analysis indicated that the odds of an APOE-ε4 carrier exhibiting telomere shortening (versus maintenance/growth) over the 2-year study were more than 6 (OR = 6.26, 95% CI = 1.02, 38.49) times higher than a non-carrier, adjusting for established risk factors and potential confounds. Despite the high-functioning, healthy mid-life status of study participants, APOE-ε4 carriers had marked telomere attrition during the 2-year study window, the equivalent of approximately one decade of additional aging compared to non-carriers. Further analyses revealed a modulatory effect of hormone therapy on the association between APOE status and telomere attrition. APOE-ε4 carriers who went off their HT regimen exhibited TL shortening, as predicted for the at-risk population. APOE-ε4 carriers who remained on HT, however, did not exhibit comparable signs of cell aging. The opposite pattern was found in non-carriers. The results suggest that hormone use might buffer against accelerated cell aging in mid-life women at risk for dementia. Importantly, for non-carrier women there was no evidence that HT conferred protective effects on telomere dynamics.

Depression is associated with an unusually high rate of aging-related illnesses and early mortality. One aspect of "accelerated aging" in depression may be shortened leukocyte telomeres. When telomeres critically shorten, as often occurs with repeated mitoses or in response to oxidation and inflammation, cells may die. Indeed, leukocyte telomere shortening predicts early mortality and medical illnesses in non-depressed populations. We sought to determine if leukocyte telomeres are shortened in Major Depressive Disorder (MDD), whether this is a function of lifetime depression exposure and whether this is related to putative mediators, oxidation and inflammation.Leukocyte telomere length was compared between 18 unmedicated MDD subjects and 17 controls and was correlated with lifetime depression chronicity and peripheral markers of oxidation (F2-isoprostane/Vitamin C ratio) and inflammation (IL-6). Analyses were controlled for age and sex.The depressed group, as a whole, did not differ from the controls in telomere length. However, telomere length was significantly inversely correlated with lifetime depression exposure, even after controlling for age (p

Leukocyte telomere length (LTL) is an emerging marker of biological age. Chronic inflammatory activity is commonly proposed as a promoter of biological aging in general, and of leukocyte telomere shortening in particular. In addition, senescent cells with critically short telomeres produce pro-inflammatory factors. However, in spite of the proposed causal links between inflammatory activity and LTL, there is little clinical evidence in support of their covariation and interaction.To address this issue, we examined if individuals with high levels of the systemic inflammatory markers interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP) had increased odds for short LTL. Our sample included 1,962 high-functioning adults who participated in the Health, Aging and Body Composition Study (age range: 70-79 years). Logistic regression analyses indicated that individuals with high levels of either IL-6 or TNF-α had significantly higher odds for short LTL. Furthermore, individuals with high levels of both IL-6 and TNF-α had significantly higher odds for short LTL compared with those who had neither high (OR = 0.52, CI = 0.37-0.72), only IL-6 high (OR = 0.57, CI = 0.39-0.83) or only TNF-α high (OR = 0.67, CI = 0.46-0.99), adjusting for a wide variety of established risk factors and potential confounds. In contrast, CRP was not associated with LTL.Results suggest that cumulative inflammatory load, as indexed by the combination of high levels of IL-6 and TNF-α, is associated with increased odds for short LTL. In contrast, high levels of CRP were not accompanied by short LTL in this cohort of older adults. These data provide the first large-scale demonstration of links between inflammatory markers and LTL in an older population.

Telomeres shorten as cells divide. This shortening is compensated by the enzyme telomerase. We evaluated the effect of common variants in the telomerase RNA component (TERC) gene on telomere length (TL) in the population-based Health Aging and Body Composition (Health ABC) Study and in two replication samples (the TwinsUK Study and the Amish Family Osteoporosis Study, AFOS).Five variants were identified in the TERC region by sequence analysis and only one SNP was common (rs2293607, G/A). The frequency of the G allele was 0.26 and 0.07 in white and black, respectively. Testing for association between TL and rs2293607 was performed using linear regression models or variance component analysis conditioning on relatedness among subjects.The adjusted mean TL was significantly shorter in 665 white carriers of the G allele compared to 887 non-carriers from the Health ABC Study (4.69±0.05 kbp vs. 4.86±0.04 kbp, measured by quantitative PCR, p = 0.005). This association was replicated in another white sample from the TwinsUK Study (6.90±0.03 kbp in 301 carriers compared to 7.06±0.03 kbp in 395 non-carriers, measured by Southern blots, p = 0.009). A similar pattern of association was observed in whites from the family-based AFOS and blacks from the Health ABC cohort, although not statistically significant, possibly due to the lower allele frequency in these populations. Combined analysis using 2,953 white subjects from 3 studies showed a significant association between TL and rs2293607 (β = -0.19±0.04 kbp, p = 0.001).Our study shows a significant association between a common variant in TERC and TL in humans, suggesting that TERC may play a role in telomere homeostasis.