Shorter telomere length predicts poor antidepressant response and poorer cardiometabolic indices in major depression

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.

Local enrichment of HP1alpha at telomeres alters their structure and regulation of telomere protection

Enhanced telomere maintenance is evident in malignant cancers. While telomeres are thought to be inherently heterochromatic, detailed mechanisms of how epigenetic modifications impact telomere protection and structures are largely unknown in human cancers. Here we develop a molecular tethering approach to experimentally enrich heterochromatin protein HP1α specifically at telomeres. This results in increased deposition of H3K9me3 at cancer cell telomeres. Telomere extension by telomerase is attenuated, and damage-induced foci at telomeres are reduced, indicating augmentation of telomere stability. Super-resolution STORM imaging shows an unexpected increase in irregularity of telomeric structure. Telomere-tethered chromo shadow domain (CSD) mutant I165A of HP1α abrogates both the inhibition of telomere extension and the irregularity of telomeric structure, suggesting the involvement of at least one HP1α-ligand in mediating these effects. This work presents an approach to specifically manipulate the epigenetic status locally at telomeres to uncover insights into molecular mechanisms underlying telomere structural dynamics.

Telomere attrition is associated with declines in medial temporal lobe volume and white matter microstructure in functionally independent older adults

Although leukocyte telomere length (TL) shortens over the lifespan and is associated with diseases of aging, little is known about the relationships between TL, memory, and brain structure. Sixty-nine functionally normal older adults (mean age = 71.7) were assessed at 2 time points (mean interval = 2.9 years). Linear mixed models assessed relationships between TL and hippocampal volume, fractional anisotropy, and mean diffusivity (MD) of the fornix and verbal and visual episodic memory. Unstandardized coefficients are reported in the following, and p values are not corrected for multiple comparisons. A negative baseline trend was observed between TL and fornix MD (b = -0.01, p = 0.06), but no other cross-sectional associations were significant (ps > 0.16). Greater TL shortening at follow-up was associated with greater hippocampal volume loss (b = 27.09, p < 0.001), even after controlling for global volume loss (b = 10.83, p = 0.002). Greater telomere attrition was also associated with larger increases in fornix MD (b = -0.01, p = 0.012) and decreases in fornix fractional anisotropy (b = 0.004, p = 0.002). TL was not associated with changes in episodic memory (ps > 0.23). These relationships may reflect neurobiological influences that affect both TL and brain structure, as well as the effect of TL on brain aging via mechanisms such as cellular senescence and inflammation.

Telomere length is inversely correlated with urinary stress hormone levels in healthy controls but not in un-medicated depressed individuals-preliminary findings

OBJECTIVE

Leukocyte telomere length (LTL) is a biomarker of cellular aging affected by chronic stress. The relationship of LTL to the stress hormones, cortisol and catecholamines, is unclear, as are possible differences between healthy controls (HC) and individuals with Major Depressive Disorder (MDD). This small pilot study is the first to examine the relationship between cortisol, catecholamines and LTL specifically in un-medicated MDD in comparison with HC.

METHODS

Participants included 16 un-medicated MDD subjects and 15 HC for assay of LTL, 12-hour overnight urinary free cortisol and catecholamine levels.

RESULTS

LTL, cortisol and catecholamine levels did not significantly differ between groups. In HC, a hierarchical regression analysis indicated that higher levels of cortisol were correlated with shorter LTL (p=0.003) above and beyond age and sex. Higher catecholamine levels were nearly-significant with shorter LTL (p=0.055). Neither hormone was correlated with shorter LTL in MDD (p's>0.28). To assess a possible cumulative effect of stress hormone activation, a summary score was calculated for each subject based on the number of stress hormone levels above the median for that group (HC or MDD). A significant inverse graded relationship was observed between LTL and the number of activated systems in HC (p=0.001), but not in MDD (p=0.96).

CONCLUSION

This pilot study provides preliminary evidence that stress hormone levels, especially cortisol, are inversely related to LTL in HC, but not in un-medicated MDD. Clarification of these relationships in larger samples could aid in understanding differential mechanisms underlying stress-related cellular aging in healthy and depressed populations.

Socioeconomic Status, Financial Strain, and Leukocyte Telomere Length in a Sample of African American Midlife Men

BACKGROUND

African American men in the USA experience poorer aging-related health outcomes compared to their White counterparts, partially due to socioeconomic disparities along racial lines. Greater exposure to socioeconomic strains among African American men may adversely impact health and aging at the cellular level, as indexed by shorter leukocyte telomere length (LTL). This study examined associations between socioeconomic factors and LTL among African American men in midlife, a life course stage when heterogeneity in both health and socioeconomic status are particularly pronounced.

METHODS

Using multinomial logistic regression, we examined associations between multiple measures of SES and tertiles of LTL in a sample of 92 African American men between 30 to 50 years of age.

RESULTS

Reports of greater financial strain were associated with higher odds of short versus medium LTL (odds ratio (OR)=2.21, p = 0.03). Higher income was associated with lower odds of short versus medium telomeres (OR=0.97, p = 0.04). Exploratory analyses revealed a significant interaction between educational attainment and employment status (χ ² = 4.07, p = 0.04), with greater education associated with lower odds of short versus long telomeres only among those not employed (OR=0.10, p = 0.040).

CONCLUSION

Cellular aging associated with multiple dimensions of socioeconomic adversity may contribute to poor aging-related health outcomes among African American men. Subjective appraisal of financial difficulty may impact LTL independently of objective dimensions of SES. Self-appraised success in fulfilling traditionally masculine gender roles, including being an economic provider, may be a particularly salient aspect of identity for African American men and have implications for cellular aging in this population.

The Longitudinal Relationship Between Cortisol Responses to Mental Stress and Leukocyte Telomere Attrition

CONTEXT

Chronic psychological stress has been associated with shorter telomeres, but the underlying mechanisms are poorly understood. One possibility is that the neuroendocrine responses to stress exposure are involved.

OBJECTIVE

To test the hypothesis that greater cortisol responsivity to acute stressors predicts more rapid telomere attrition.

DESIGN

We measured salivary cortisol responses to 2 challenging behavioral tasks. Leukocyte telomere length was measured at the time of mental stress testing and 3 years later.

PARTICIPANTS

We studied 411 initially healthy men and women aged 54 to 76 years.

MAIN OUTCOME MEASURE

Leukocyte telomere length.

RESULTS

Cortisol responses to this protocol were small; we divided participants into cortisol responders (n = 156) and nonresponders (n = 255) using a criterion (≥20% increase in cortisol concentration) previously shown to predict increases in cardiovascular disease risk. There was no significant association between cortisol responsivity and baseline telomere length, although cortisol responders tended to have somewhat shorter telomeres (β = -0.061; standard error, 0.049). But cortisol responders had shorter telomeres and more rapid telomere attrition than nonresponders on follow-up, after controlling statistically for age, sex, socioeconomic status, smoking, time of day of stress , and baseline telomere length (β = -0.10; standard error, 0.046; P = 0.029). The association was maintained after additional control for cardiovascular risk factors (β = -0.11; P = 0.031). The difference between cortisol responders and nonresponders was equivalent to approximately 2 years in aging.

CONCLUSIONS

These findings suggest that cortisol responsivity may mediate, in part, the relationship between psychological stress and cellular aging.

Correction: Change in Leukocyte Telomere Length Predicts Mortality in Patients with Stable Coronary Heart Disease from the Heart and Soul Study

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

Leukocyte Telomere Length in Relation to 17 Biomarkers of Cardiovascular Disease Risk: A Cross-Sectional Study of US Adults

BACKGROUND

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.

METHODS AND FINDINGS

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.

CONCLUSIONS

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.

Change in Leukocyte Telomere Length Predicts Mortality in Patients with Stable Coronary Heart Disease from the Heart and Soul Study

Background

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.

Methods

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.

Results

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<0.001). As compared with patients whose telomere length was maintained, those who experienced telomere lengthening were 56% less likely to die (HR 0.44, 95% CI, 0.23–0.87).

Conclusions

In patients with coronary heart disease, an increase in leukocyte telomere length over 5 years is associated with decreased mortality.

Sugary beverage and food consumption, and leukocyte telomere length maintenance in pregnant women

Leukocyte telomere length (LTL) has been inversely associated with sugar-sweetened beverage (SSB) consumption in cross-sectional studies, but no studies have examined whether dietary intake influences LTL over time. This study examined longitudinal associations between sugary foods and beverages and LTL. Participants were 65 overweight and obese pregnant women, aged 18-45 years, from a mindfulness intervention study conducted from early pregnancy (⩽16 weeks gestation) and followed through 9 months postpartum. During pregnancy and postpartum, dietary intake was measured with 24-h diet recalls, and LTL was assessed using quantitative PCR. Adjusting for sociodemographic and health characteristics, decreased SSB consumption from baseline to 9 months postpartum was associated with greater concurrent LTL lengthening (β=-0.102, 95% confidence interval (CI) -0.192, -0.013). No associations between sugary foods and LTL were found in either period. The finding that reduced SSB consumption is associated with increased LTL warrants investigation in large cohort studies.

Meditation and vacation effects have an impact on disease-associated molecular phenotypes

Meditation is becoming increasingly practiced, especially for stress-related medical conditions. Meditation may improve cellular health; however, studies have not separated out effects of meditation from vacation-like effects in a residential randomized controlled trial. We recruited healthy women non-meditators to live at a resort for 6 days and randomized to either meditation retreat or relaxing on-site, with both groups compared with 'regular meditators' already enrolled in the retreat. Blood drawn at baseline and post intervention was assessed for transcriptome-wide expression patterns and aging-related biomarkers. Highly significant gene expression changes were detected across all groups (the 'vacation effect') that could accurately predict (96% accuracy) between baseline and post-intervention states and were characterized by improved regulation of stress response, immune function and amyloid beta (Aβ) metabolism. Although a smaller set of genes was affected, regular meditators showed post-intervention differences in a gene network characterized by lower regulation of protein synthesis and viral genome activity. Changes in well-being were assessed post intervention relative to baseline, as well as 1 and 10 months later. All groups showed equivalently large immediate post-intervention improvements in well-being, but novice meditators showed greater maintenance of lower distress over time compared with those in the vacation arm. Regular meditators showed a trend toward increased telomerase activity compared with randomized women, who showed increased plasma Aβ42/Aβ40 ratios and tumor necrosis factor alpha (TNF-α) levels. This highly controlled residential study showed large salutary changes in gene expression networks due to the vacation effect, common to all groups. For those already trained in the practice of meditation, a retreat appears to provide additional benefits to cellular health beyond the vacation effect.

Abstract LB-161: Exploiting non-canonical heterochromatin-mediated telomere protection mechanisms in human cells

Mammalian telomeres are inherently heterochromatic. While enhanced telomere maintenance is evident in malignant cancers, some cancers appear to maintain telomeres by neither the common telomerase nor the alternative telomere repeat recombination mechanisms. Specifically, the roles of epigenetic modifications in telomere protection are largely unknown in human cancers. I have combined newly developed cellular and molecular approaches to show that in some cancer cell types, experimentally enhanced heterochromatinization localized specifically at telomeres reduced damage-induced foci at telomeres, suggesting augmentation of telomere stability. These results lead to the intriguing hypothesis that manipulating the epigenetic status at telomeres may be exploited to elicit damage at the telomeres of cancer cells as a novel approach to fight cancer. My current work in progress focuses on identifying novel chromatin modifiers that weaken telomere protection by modulating telomere compaction. It is especially urgent to understand the plasticity and modes of telomere protection by which some human cancers escape the requirement of telomerase activation to sustain immortalization. Results from this work can potentially advance the development of novel combinatorial telomere-directed cancer treatments.

Citation Format: Tracy T. Chow, Elizabeth H. Blackburn. Exploiting non-canonical heterochromatin-mediated telomere protection mechanisms in human cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-161.

Leukocyte telomere length predicts SSRI response in major depressive disorder: A preliminary report

Short leukocyte telomere length (LTL) may be associated with several psychiatric disorders, including major depressive disorder (MDD). Short LTL has previously been associated with poor response to psychiatric medications in bipolar disorder and schizophrenia, but no studies have prospectively assessed the relationship of LTL to SSRI response in MDD. We assessed pre-treatment LTL, depression severity (using the Hamilton Depression Rating Scale [HDRS]), and self-reported positive and negative affect in 27 healthy, unmedicated adults with MDD. Subjects then underwent open-label treatment with a selective serotonin reuptake inhibitor (SSRI) antidepressant for eight weeks, after which clinical ratings were repeated. Analyses were corrected for age, sex and BMI. "Non-responders" to treatment (HDRS improvement <50%) had significantly shorter pre-treatment LTL, compared to "Responders" (p=0.037). Further, shorter pre-treatment LTL was associated with less improvement in negative affect (p<0.010) but not with changes in positive affect (p=0.356). This preliminary study is the first to assess the relationship between LTL and SSRI response in MDD and among the first to prospectively assess its relationship to treatment outcome in any psychiatric illness. Our data suggest that short LTL may serve as a vulnerability index of poorer response to SSRI treatment, but this needs examination in larger samples.

Human telomere biology: A contributory and interactive factor in aging, disease risks, and protection

Telomeres are the protective end-complexes at the termini of eukaryotic chromosomes. Telomere attrition can lead to potentially maladaptive cellular changes, block cell division, and interfere with tissue replenishment. Recent advances in the understanding of human disease processes have clarified the roles of telomere biology, especially in diseases of human aging and in some aging-related processes. Greater overall telomere attrition predicts mortality and aging-related diseases in inherited telomere syndrome patients, and also in general human cohorts. However, genetically caused variations in telomere maintenance either raise or lower risks and progression of cancers, in a highly cancer type-specific fashion. Telomere maintenance is determined by genetic factors and is also cumulatively shaped by nongenetic influences throughout human life; both can interact. These and other recent findings highlight both causal and potentiating roles for telomere attrition in human diseases.

Abstract A26: Telomere length in normal and tumor breast tissue from BRCA2 mutation carriers and sporadic breast cancer cases

Germline mutations in the BRCA genes are associated with highly increased risk of breast and ovarian cancers and to a lesser extent to prostate and pancreatic cancers. Great number of mutations with variable impact on cancer risk and progression are known in these genes worldwide. A single founder mutation has been detected in each of the BRCA genes in the Icelandic population, making it feasible to study the influence of a single mutation at a population level. The BRCA2999del5 mutation is more frequent and can be found in approximately 6-7% of female breast cancer patients and 40% of male breast cancer patients in Iceland. The mutation leads to a non-functional protein product and is associated with complex chromosomal changes in tumor tissue. Furthermore, the BRCA2999del5 mutation has been associated with poor prognosis, both in breast and prostate cancers, although mutation carriers seem to differ with respect to age of onset and severity of disease.

Dysfunctional telomere maintenance can lead to excessive telomere shortening which causes chromosome instability. It is therefore a driving force behind cancer progression and is considered a hallmark of many human cancers. Telomere shortening has been shown to be an early and a common molecular alteration in epithelial cancers, including breast cancers. Previous results from our laboratory, amongst others, have shown that BRCA2 is associated with telomere protection and maintenance. Telomere dysfunction induced foci (TIFs) formation was detected in cell lines derived from heterozygous BRCA2999del5 mutation carriers1. Telomere length has been proposed as a possible predictive factor for cancer risk for various cancers. In the case of breast cancer and BRCA mutation carriers, the results have been conflicting.

The aim of the study was to investigate if telomere length in normal and tumor breast tissue is correlated with breast cancer progression and survival in a well-defined group of BRCA2 mutation carriers and sporadic breast cancer cases.

The study group consisted of breast cancer patients carrying the BRCA2999del5 Icelandic founder mutation and sporadic cases, matched with respect to age and year of diagnosis. Tumor and normal adjacent tissue samples from these patients were embedded in paraffin and Quantitative Fluorescence in Situ Hybridization method (Q-FISH) was used to carry out telomere length measurements. Telomeres were visualized using a telomeric sequence-specific fluorescence peptide nucleic acid (PNA) probe. A centromere-specific PNA probe was used as an inner control for hybridization efficiency.

The results show a clear difference in telomere length of different cell types in normal breast tissue with inner epithelial cells having shorter telomeres than both myoepithelial cells and fibroblasts. These findings support previously reported data in the literature2. The majority of examined tumors have very short telomeres. In mutation carriers, there are indications that less variable telomere length in normal adjacent tissue is associated with reduced breast cancer specific survival. This seems to be more pronounced in the mutation carrier group compared to the sporadic group. Telomere length in adjacent normal tissue appears to be shorter in cases with luminal type than with basal-like tumors.

References:

1. Bodvarsdottir, S. K., Steinarsdottir, M., Bjarnason, H. & Eyfjord, J. E. Dysfunctional telomeres in human BRCA2 mutated breast tumors and cell lines. Mutat. Res. Mol. Mech. Mutagen. 729, 90–99 (2012).

2. Kurabayashi, R. et al. Luminal and cancer cells in the breast show more rapid telomere shortening than myoepithelial cells and fibroblasts. Hum. Pathol. 39, 1647–1655 (2008).

Citation Format: Birna Thorvaldsdottir, Beth A. Cimini, Morgan E. Diolaiti, Margret Aradottir, Katrin Olafsdottir, Jon G. Jonasson, Elizabeth H. Blackburn, Jorunn E. Eyfjörd. Telomere length in normal and tumor breast tissue from BRCA2 mutation carriers and sporadic breast cancer cases. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr A26.

Association of dimensional psychological health measures with telomere length in male war veterans

BACKGROUND

Several psychiatric disorders may be characterized by peripheral telomere shortening. However, it is unclear whether telomere shortening is associated with these psychiatric disorders per se or, rather, with underlying dimensional parameters that are often, but not necessarily, associated with them. We explored the association between dimensional psychopathological measures and telomere length (TL) in granulocytes among veterans independent of psychiatric diagnosis.

METHODS

Seventy-six combat-exposed male veterans (41 psychiatrically healthy, 18 with Posttraumatic Stress Disorder [PTSD] and 17 with concomitant PTSD and Major Depressive Disorder [MDD]) had TL assayed. Assessments included Clinician-Administered PTSD Scale (CAPS), Beck Depression Inventory-II (BDI-II), Early Trauma Inventory (ETI), Symptom Checklist-90-R Global Severity Index (SCL-90-GSI), Perceived Stress Scale (PSS) and Positive and Negative Affect Schedule (PANAS). Correlations were corrected for age, BMI, antidepressants and ethnicity.

RESULTS

Across subjects, TL was negatively correlated with early trauma (p<0.001), global psychopathological severity (p=0.044) and perceived stress (p=0.019), positively correlated with positive affect (p=0.026), not significantly correlated with symptom severity of PTSD, depression or negative affect. Across these dimensions, early trauma and positive affect were associated with TL after excluding subjects with somatic illnesses.

LIMITATIONS

The study was cross-sectional with a moderate sample size and only male combat-exposed subjects.

CONCLUSIONS

These preliminary findings suggest that early trauma, severity of perceived stress and general psychopathological symptoms are more closely associated with shorter TL than is the severity of core diagnostic symptoms of PTSD or MDD, whereas positive affect is associated with longer TL. Larger-scale studies should assess TL associated with specific psychiatric dimensions, apart from only categorical psychiatric diagnoses, to develop more specific biologically-relevant endophenotypes.

Mitochondrial DNA copy number is reduced in male combat veterans with PTSD

INTRODUCTION

Mitochondrial abnormalities may be involved in PTSD, although few studies have examined this. Mitochondrial DNA copy number (mtDNAcn) in blood cells is an emerging systemic index of mitochondrial biogenesis and function. The present study assessed mtDNAcn in male combat-exposed veterans with PTSD compared to those without PTSD as well as its correlation with clinical scales.

METHODS

mtDNAcn was assessed with a TaqMan multiplex assay in granulocytes of 43 male combat veterans with (n=43) or without (n=44) PTSD. Twenty of the PTSD subjects had co-morbid major depressive disorder (MDD). The Clinician Administered PTSD Scale (CAPS), the Positive and Negative Affect Schedule (PANAS), the Early Trauma Inventory (ETI) and the Beck Depression Inventory II (BDI-II) were used for the clinical assessments. All analyses were corrected for age and BMI.

RESULTS

mtDNAcn was significantly lower in subjects with PTSD (p<0.05). Within the PTSD group, those with moderate PTSD symptom severity had relatively higher mtDNAcn than those with mild or severe symptoms (p<0.01). Within the PTSD group, mtDNAcn was positively correlated with PANAS positive subscale ratings (p<0.01) but was not significantly correlated with PANAS negative subscale, ETI or BDI-II ratings.

DISCUSSION

This study provides the first evidence of: (i) a significant decrease of mtDNAcn in combat PTSD, (ii) a possible "inverted-U" shaped relationship between PTSD symptom severity and mtDNAcn within PTSD subjects, and (iii) a direct correlation of mtDNAcn with positive affectivity within PTSD subjects. Altered mtDNAcn in PTSD may reflect impaired energy metabolism, which might represent a novel aspect of its pathophysiology.

Discrimination, mental health, and leukocyte telomere length among African American men

African American men in the US experience disparities across multiple health outcomes. A common mechanism underlying premature declines in health may be accelerated biological aging, as reflected by leukocyte telomere length (LTL). Racial discrimination, a qualitatively unique source of social stress reported by African American men, in tandem with poor mental health, may negatively impact LTL in this population. The current study examined cross-sectional associations between LTL, self-reported racial discrimination, and symptoms of depression and anxiety among 92 African American men 30-50 years of age. LTL was measured in kilobase pairs using quantitative polymerase chain reaction assay. Controlling for sociodemographic factors, greater anxiety symptoms were associated with shorter LTL (b=-0.029, standard error [SE]=0.014; p<0.05). There were no main effects of racial discrimination or depressive symptoms on LTL, but we found evidence for a significant interaction between the two (b=0.011, SE=0.005; p<0.05). Racial discrimination was associated with shorter LTL among those with lower levels of depressive symptoms. Findings from this study highlight the role of social stressors and individual-level psychological factors for physiologic deterioration among African American men. Consistent with research on other populations, greater anxiety may reflect elevated stress associated with shorter LTL. Racial discrimination may represent an additional source of social stress among African American men that has detrimental consequences for cellular aging among those with lower levels of depression.

Peripheral telomere length and hippocampal volume in adolescents with major depressive disorder

Several studies have reported that adults with major depressive disorder have shorter telomere length and reduced hippocampal volumes. Moreover, studies of adult populations without major depressive disorder suggest a relationship between peripheral telomere length and hippocampal volume. However, the relationship of these findings in adolescents with major depressive disorder has yet to be explored. We examined whether adolescent major depressive disorder is associated with altered peripheral telomere length and hippocampal volume, and whether these measures relate to one another. In 54 unmedicated adolescents (13-18 years) with major depressive disorder and 63 well-matched healthy controls, telomere length was assessed from saliva using quantitative polymerase chain reaction methods, and bilateral hippocampal volumes were measured with magnetic resonance imaging. After adjusting for age and sex (and total brain volume in the hippocampal analysis), adolescents with major depressive disorder exhibited significantly shorter telomere length and significantly smaller right, but not left hippocampal volume. When corrected for age, sex, diagnostic group and total brain volume, telomere length was not significantly associated with left or right hippocampal volume, suggesting that these cellular and neural processes may be mechanistically distinct during adolescence. Our findings suggest that shortening of telomere length and reduction of hippocampal volume are already present in early-onset major depressive disorder and thus unlikely to be only a result of accumulated years of exposure to major depressive disorder.

Movement-Based Behaviors and Leukocyte Telomere Length among US Adults

INTRODUCTION

Short leukocyte telomere length (LTL) has become a hallmark characteristic of aging. Some, but not all, evidence suggests that physical activity (PA) may play an important role in attenuating age-related diseases and may provide a protective effect for telomeres. The purpose of this study was to examine the association between PA and LTL in a national sample of US adults from the National Health and Nutrition Examination Survey.

METHODS

National Health and Nutrition Examination Survey data from 1999 to 2002 (n = 6503; 20-84 yr) were used. Four self-report questions related to movement-based behaviors (MBB) were assessed. The four MBB included whether individuals participated in moderate-intensity PA, vigorous-intensity PA, walking/cycling for transportation, and muscle-strengthening activities. An MBB index variable was created by summing the number of MBB an individual engaged in (range, 0-4).

RESULTS

A clear dose-response relation was observed between MBB and LTL; across the LTL tertiles, respectively, the mean numbers of MBB were 1.18, 1.44, and 1.54 (Ptrend < 0.001). After adjustments (including age) and compared with those engaging in 0 MBB, those engaging in 1, 2, 3, and 4 MBB, respectively, had a 3% (P = 0.84), 24% (P = 0.02), 29% (P = 0.04), and 52% (P = 0.004) reduced odds of being in the lowest (vs highest) tertile of LTL; MBB was not associated with being in the middle (vs highest) tertile of LTL.

CONCLUSIONS

Greater engagement in MBB was associated with reduced odds of being in the lowest LTL tertile.

Psychiatric disorders and leukocyte telomere length: Underlying mechanisms linking mental illness with cellular aging

Many psychiatric illnesses are associated with early mortality and with an increased risk of developing physical diseases that are more typically seen in the elderly. Moreover, certain psychiatric illnesses may be associated with accelerated cellular aging, evidenced by shortened leukocyte telomere length (LTL), which could underlie this association. Shortened LTL reflects a cell's mitotic history and cumulative exposure to inflammation and oxidation as well as the availability of telomerase, a telomere-lengthening enzyme. Critically short telomeres can cause cells to undergo senescence, apoptosis or genomic instability, and shorter LTL correlates with poorer health and predicts mortality. Emerging data suggest that LTL may be reduced in certain psychiatric illnesses, perhaps in proportion to exposure to the psychiatric illnesses, although conflicting data exist. Telomerase has been less well characterized in psychiatric illnesses, but a role in depression and in antidepressant and neurotrophic effects has been suggested by preclinical and clinical studies. In this article, studies on LTL and telomerase activity in psychiatric illnesses are critically reviewed, potential mediators are discussed, and future directions are suggested. A deeper understanding of cellular aging in psychiatric illnesses could lead to re-conceptualizing them as systemic illnesses with manifestations inside and outside the brain and could identify new treatment targets.

Maternal Folate Concentration in Early Pregnancy and Newborn Telomere Length

BACKGROUND/AIMS

Telomere biology plays a fundamental role in genomic integrity and cell physiology. The newborn setting of telomere length (TL) likely has important implications for telomere dynamics over the lifespan; however, its determinants are poorly understood. Folate is essential for DNA integrity. The maternal compartment is the only source of folate for the developing fetus. We, therefore, tested the hypothesis that variation in maternal folate during pregnancy is associated with newborn TL.

METHODS

A prospective, longitudinal study was conducted in 119 mother-newborn dyads. Eligible mothers were enrolled at 9.5 (SD ±2.1) weeks gestation and followed through birth. Concentrations of maternal serum folate were measured in the first trimester of pregnancy. Newborn telomere length was measured in cord blood mononuclear cells (CBMC).

RESULTS

After accounting for the effects of other established determinants of newborn TL, each 10 ng/ml increase in maternal total folate was associated with a 5.8% increase in median TL (p = 0.03). The median TL in newborns of mother in the lowest quartile of total folate levels was approximately 10% shorter than that of newborns of mothers in the highest folate quartile.

CONCLUSIONS

Our findings suggest that fetal TL exhibits developmental plasticity, and provide evidence that maternal nutrition may exert a 'programming' effect on this system.

Race-Ethnicity, Poverty, Urban Stressors, and Telomere Length in a Detroit Community-based Sample

Residents of distressed urban areas suffer early aging-related disease and excess mortality. Using a community-based participatory research approach in a collaboration between social researchers and cellular biologists, we collected a unique data set of 239 black, white, or Mexican adults from a stratified, multistage probability sample of three Detroit neighborhoods. We drew venous blood and measured telomere length (TL), an indicator of stress-mediated biological aging, linking respondents' TL to their community survey responses. We regressed TL on socioeconomic, psychosocial, neighborhood, and behavioral stressors, hypothesizing and finding an interaction between poverty and racial-ethnic group. Poor whites had shorter TL than nonpoor whites; poor and nonpoor blacks had equivalent TL; and poor Mexicans had longer TL than nonpoor Mexicans. Findings suggest unobserved heterogeneity bias is an important threat to the validity of estimates of TL differences by race-ethnicity. They point to health impacts of social identity as contingent, the products of structurally rooted biopsychosocial processes.

PBMC telomerase activity, but not leukocyte telomere length, correlates with hippocampal volume in major depression

Accelerated cell aging, indexed in peripheral leukocytes by telomere shortness and in peripheral blood mononuclear cells (PBMCs) by telomerase activity, has been reported in several studies of major depressive disorder (MDD). However, the relevance of these peripheral measures for brain indices that are presumably more directly related to MDD pathophysiology is unknown. In this study, we explored the relationship between PBMC telomerase activity and leukocyte telomere length and magnetic resonance imaging-estimated hippocampal volume in un-medicated depressed individuals and healthy controls. We predicted that, to the extent peripheral and central telomerase activity are directly related, PBMC telomerase activity would be positively correlated with hippocampal volume, perhaps due to hippocampal telomerase-associated neurogenesis, neuroprotection or neurotrophic facilitation, and that this effect would be clearer in individuals with increased PBMC telomerase activity, as previously reported in un-medicated MDD. We did not have specific hypotheses regarding the relationship between leukocyte telomere length and hippocampal volume, due to conflicting reports in the published literature. We found, in 25 un-medicated MDD subjects, that PBMC telomerase activity was significantly positively correlated with hippocampal volume; this relationship was not observed in 18 healthy controls. Leukocyte telomere length was not significantly related to hippocampal volume in either group (19 unmedicated MDD subjects and 17 healthy controls). Although the nature of the relationship between peripheral telomerase activity and telomere length and the hippocampus is unclear, these preliminary data are consistent with the possibility that PBMC telomerase activity indexes, and may provide a novel window into, hippocampal neuroprotection and/or neurogenesis in MDD.

Early telomerase inactivation accelerates aging independently of telomere length

Telomerase is required for long-term telomere maintenance and protection. Using single budding yeast mother cell analyses we found that, even early after telomerase inactivation (ETI), yeast mother cells show transient DNA damage response (DDR) episodes, stochastically altered cell-cycle dynamics, and accelerated mother cell aging. The acceleration of ETI mother cell aging was not explained by increased reactive oxygen species (ROS), Sir protein perturbation, or deprotected telomeres. ETI phenotypes occurred well before the population senescence caused late after telomerase inactivation (LTI). They were morphologically distinct from LTI senescence, were genetically uncoupled from telomere length, and were rescued by elevating dNTP pools. Our combined genetic and single-cell analyses show that, well before critical telomere shortening, telomerase is continuously required to respond to transient DNA replication stress in mother cells and that a lack of telomerase accelerates otherwise normal aging.

Determinants of telomere attrition over 1 year in healthy older women: stress and health behaviors matter

Telomere length, a reliable predictor of disease pathogenesis, can be affected by genetics, chronic stress and health behaviors. Cross-sectionally, highly stressed postmenopausal women have shorter telomeres, but only if they are inactive. However, no studies have prospectively examined telomere length change over a short period, and if rate of attrition is affected by naturalistic factors such as stress and engagement in healthy behaviors, including diet, exercise, and sleep. Here we followed healthy women over 1 year to test if major stressors that occurred over the year predicted telomere shortening, and whether engaging in healthy behaviors during this period mitigates this effect. In 239 postmenopausal, non-smoking, disease-free women, accumulation of major life stressors across a 1-year period predicted telomere attrition over the same period-for every major life stressor that occurred during the year, there was a significantly greater decline in telomere length over the year of 35 bp (P<0.05). Yet, these effects were moderated by health behaviors (interaction B=0.19, P=0.04). Women who maintained relatively higher levels of health behaviors (1 s.d. above the mean) appeared to be protected when exposed to stress. This finding has implications for understanding malleability of telomere length, as well as expectations for possible intervention effects. This is the first study to identify predictors of telomere length change over the short period of a year.

Associations of cadmium and lead exposure with leukocyte telomere length: findings from National Health and Nutrition Examination Survey, 1999-2002

Cadmium and lead are ubiquitous environmental contaminants that might increase risks of cardiovascular disease and other aging-related diseases, but their relationships with leukocyte telomere length (LTL), a marker of cellular aging, are poorly understood. In experimental studies, they have been shown to induce telomere shortening, but no epidemiologic study to date has examined their associations with LTL in the general population. We examined associations of blood lead and cadmium (n = 6,796) and urine cadmium (n = 2,093) levels with LTL among a nationally representative sample of US adults from the National Health and Nutrition Examination Survey (1999-2002). The study population geometric mean concentrations were 1.67 µg/dL (95% confidence interval (CI): 1.63, 1.70) for blood lead, 0.44 µg/L (95% CI: 0.42, 0.47) for blood cadmium, and 0.28 µg/L (95% CI: 0.27, 0.30) for urine cadmium. After adjustment for potential confounders, the highest (versus lowest) quartiles of blood and urine cadmium were associated with -5.54% (95% CI: -8.70, -2.37) and -4.50% (95% CI: -8.79, -0.20) shorter LTLs, respectively, with evidence of dose-response relationship (P for trend < 0.05). There was no association between blood lead concentration and LTL. These findings provide further evidence of physiological impacts of cadmium at environmental levels and might provide insight into biological pathways underlying cadmium toxicity and chronic disease risks.

Maternal estriol concentrations in early gestation predict infant telomere length

CONTEXT

Telomere biology plays a fundamental role in genomic integrity, cellular regeneration, physiology, aging, disease risk, and mortality. The initial setting of telomere length (TL) in early life has important implications for telomere maintenance and related disorders throughout the life span. However, little is known about the predictors of this initial setting.

OBJECTIVE

Given the established role of estrogen on adult TL and the role of estriol (E3) in the context of fetal development, the goal of this study was to test the hypothesis that higher maternal E3 concentration during early pregnancy is associated with longer infant telomere length.

DESIGN, PARTICIPANTS, AND SETTING

Study participants comprised a cohort of N = 100 infants followed prospectively from intrauterine life and birth through early childhood from a population-based, representative sample of pregnant mothers recruited in early pregnancy at university-based obstetric clinics in Southern California. Maternal unconjugated E3 concentrations were assessed in plasma in early gestation (around wk 15). Infant TL was assessed in buccal cells at approximately 15 months of age.

RESULTS

After accounting for the effects of potential confounding maternal and infant variables, there was a significant, independent effect of maternal E3 concentration on infant TL (unstandardized β = 0.297; P = .001; 95% Cl, 0.121-0.473). Specifically, a one-multiple-of-the-median (MoM) increase in maternal E3 concentration during early pregnancy was associated with a 14.42% increase in infant TL.

CONCLUSIONS

This study supports the concept of developmental plasticity of the telomere biology system and highlights specifically the role of a potentially modifiable intrauterine factor for additional mechanistic and clinical investigation.

An antiapoptotic role for telomerase RNA in human immune cells independent of telomere integrity or telomerase enzymatic activity

Telomerase is a ribonucleoprotein complex that adds telomeric DNA to the ends of linear chromosomes. It contains two core canonical components: the essential RNA component, hTR, which provides the template for DNA synthesis, and the reverse transcriptase protein component, hTERT. Low telomerase activity in circulating peripheral blood mononuclear cells has been associated with a variety of diseases. It is unknown, however, whether telomerase, in addition to its long-term requirement for telomere maintenance, is also necessary for short-term immune cell proliferation and survival. We report that overexpression of enzymatically inactive hTR mutants protected against dexamethasone-induced apoptosis in stimulated CD4 T cells. Furthermore, hTR knockdown reproducibly induced apoptosis in the absence of any detectable telomere shortening or DNA damage response. In contrast, hTERT knockdown did not induce apoptosis. Strikingly, overexpression of hTERT protein caused apoptosis that was rescued by overexpression of enzymatically inactive hTR mutants. Hence, we propose that hTR can function as a noncoding RNA that protects from apoptosis independent of its function in telomerase enzymatic activity and long-term telomere maintenance in normal human immune cells. These results imply that genetic or environmental factors that alter hTR levels can directly affect immune cell function to influence health and disease.

Adverse childhood experiences and leukocyte telomere maintenance in depressed and healthy adults

BACKGROUND

Adverse childhood experiences (ACEs) are associated with poor physical and mental health outcomes in adulthood. Adverse childhood experiences are also associated with shortened leukocyte telomere length (LTL) in adults, suggesting accelerated cell aging. No studies have yet assessed the relationship of ACEs to LTL in individuals with major depressive disorder (MDD), despite the high incidence of antecedent ACEs in individuals with MDD. Further, no studies in any population have assessed the relationship of ACEs to the activity of telomerase, the major enzyme responsible for maintaining LTL, or the relationship between telomerase and LTL in individuals with ACEs.

METHODS

Twenty healthy, unmedicated adults with MDD and 20 healthy age-, sex- and ethnicity-matched controls had ACEs assessed and had blood drawn for LTL and peripheral blood mononuclear cell (PBMC) resting telomerase activity.

RESULTS

In healthy controls, greater ACE exposure was associated with shorter LTL (p<.05) but was unassociated with telomerase activity. In MDD, however, the opposite pattern was seen: greater ACE exposure was unrelated to LTL but was associated with increased telomerase activity (p<.05) and with a higher telomerase:LTL ratio (p=.022).

LIMITATIONS

Study limitations include the small sample size, a single timepoint assessment of telomerase activity, and the use of retrospective self-report to assess ACEs.

CONCLUSIONS

These results replicate prior findings of shortened LTL in healthy adults with histories of multiple ACEs. However, in MDD, this relationship was substantially altered, raising the possibility that activation of telomerase in ACE-exposed individuals with MDD could represent a compensatory response to endangered telomeres.

Telomere length and the risk of atrial fibrillation: insights into the role of biological versus chronological aging

BACKGROUND

Advanced age is the most important risk factor for atrial fibrillation (AF); however, the mechanism remains unknown. Telomeres, regions of DNA that shorten with cell division, are considered reliable markers of biological aging. We sought to examine the association between leukocyte telomere length (LTL) and incident AF in a large population-based cohort using direct LTL measurements and genetic data. To further explore our findings, we compared atrial cell telomere length and LTL in cardiac surgery patients.

METHODS AND RESULTS

Mean LTL and the TERT rs2736100 single nucleotide polymorphism were assessed as predictors of incident AF in the Cardiovascular Health Study (CHS). Among the surgical patients, within subject comparison of atrial cell telomere length versus LTL was assessed. Among 1639 CHS participants, we observed no relationship between mean LTL and incident AF before and after adjustment for potential confounders (adjusted hazard ratio, 1.09; 95% confidence interval: 0.92-1.29; P=0.299); chronologic age remained strongly associated with AF in the same model. No association was observed between the TERT rs2736100 single nucleotide polymorphism and incident AF (adjusted hazard ratio: 0.95; 95% confidence interval: 0.88-1.04; P=0.265). In 35 cardiac surgery patients (26 with AF), atrial cell telomere length was longer than LTL (1.19 ± 0.20 versus 1.02 ± 0.25 [T/S ratio], P<0.001), a finding that remained consistent within the AF subgroup.

CONCLUSIONS

Our study revealed no evidence of an association between LTL and incident AF and no evidence of relative atrial cell telomere shortening in AF. Chronological aging independent of biological markers of aging is the primary risk factor for AF.

Soda and cell aging: associations between sugar-sweetened beverage consumption and leukocyte telomere length in healthy adults from the National Health and Nutrition Examination Surveys

OBJECTIVES

We tested whether leukocyte telomere length maintenance, which underlies healthy cellular aging, provides a link between sugar-sweetened beverage (SSB) consumption and the risk of cardiometabolic disease.

METHODS

We examined cross-sectional associations between the consumption of SSBs, diet soda, and fruit juice and telomere length in a nationally representative sample of healthy adults. The study population included 5309 US adults, aged 20 to 65 years, with no history of diabetes or cardiovascular disease, from the 1999 to 2002 National Health and Nutrition Examination Surveys. Leukocyte telomere length was assayed from DNA specimens. Diet was assessed using 24-hour dietary recalls. Associations were examined using multivariate linear regression for the outcome of log-transformed telomere length.

RESULTS

After adjustment for sociodemographic and health-related characteristics, sugar-sweetened soda consumption was associated with shorter telomeres (b = -0.010; 95% confidence interval [CI] = -0.020, -0.001; P = .04). Consumption of 100% fruit juice was marginally associated with longer telomeres (b = 0.016; 95% CI = -0.000, 0.033; P = .05). No significant associations were observed between consumption of diet sodas or noncarbonated SSBs and telomere length.

CONCLUSIONS

Regular consumption of sugar-sweetened sodas might influence metabolic disease development through accelerated cell aging.

Seasonal variation of peripheral blood leukocyte telomere length in Costa Rica: A population-based observational study

OBJECTIVES

Peripheral blood leukocyte telomere length (LTL) is increasingly being used as a biomarker of aging, but its natural variation in human populations is not well understood. Several other biomarkers show seasonal variation, as do several determinants of LTL. We examined whether there was monthly variation in LTL in Costa Rica, a country with strong seasonal differences in precipitation and infection.

METHODS

We examined a longitudinal population-based cohort of 581 Costa Rican adults age 60 and above, from which blood samples were drawn between October 2006 and July 2008. LTL was assayed from these samples using the quantitative PCR method. Multivariate regression models were used to examine correlations between month of blood draw and LTL.

RESULTS

Telomere length from peripheral blood leukocytes varied by as much as 200 base pairs depending on month of blood draw, and this difference is not likely to be due to random variation. A moderate proportion of this association is statistically accounted for by month and region specific average rainfall. We found shorter telomere length associated with greater rainfall.

CONCLUSIONS

There are two possible explanations of our findings. First, there could be relatively rapid month-to-month changes in LTL. This conclusion would have implications for understanding the natural population dynamics of telomere length. Second, there could be seasonal differences in constituent cell populations. This conclusion would suggest that future studies of LTL use methods to account for the potential impact of constituent cell type.

Multisystem resiliency moderates the major depression-telomere length association: findings from the Heart and Soul Study

Major depressive disorder (MDD) has been associated with reduced leukocyte telomere length (LTL). It is not known, however, whether psychosocial and behavioral protective factors moderate this association. In the current study, we examine whether multisystem resiliency--defined by healthy emotion regulation, strong social connections, and health behaviors (sleep and exercise)--predicts LTL and mitigates previously demonstrated associations between depression diagnosis and LTL. LTL was measured, using a quantitative PCR assay, in 954 patients with stable cardiovascular disease in the Heart and Soul Study. In a fully adjusted model, high multisystem resiliency predicted longer LTL (b=80.00, SE=27.17, p=.003), whereas each individual factor did not. Multisystem resiliency significantly moderated the MDD-LTL association (p=.02). Specifically, MDD was significantly related to LTL at 1 SD below the mean of multisystem resiliency (b=-142.86, SE=56.46, p=.01), but not at 1 SD above the mean (b=49.07, SE=74.51, p=.51). This study suggests that MDD associations with biological outcomes should be examined within a psychosocial-behavioral context, because this context shapes the nature of the direct relationship. Further research should explore the cognitive, neural, and other physiological pathways through which multisystem resiliency may confer biological benefit.

Longer leukocyte telomere length in Costa Rica's Nicoya Peninsula: a population-based study

Studies in humans suggest that leukocyte telomere length may act as a marker of biological aging. We investigated whether individuals in the Nicoya region of Costa Rica, known for exceptional longevity, had longer telomere length than those in other parts of the country. After controlling for age, age squared, rurality, rainy season and gender, the mean leukocyte telomere length in Nicoya was substantially longer (81 base pairs, p<0.05) than in other areas of Costa Rica, providing evidence of a biological pathway to which this notable longevity may be related. This relationship remains unchanged (79 base pairs, p<0.05) after statistically controlling for nineteen potential biological, dietary and social and demographic mediators. Thus the difference in the mean leukocyte telomere length that characterizes this unique region does not appear to be explainable by traditional behavioral and biological risk factors. More detailed examination of mean leukocyte telomere length by age shows that the regional telomere length difference declines at older ages.

The major reverse transcriptase-incompetent splice variant of the human telomerase protein inhibits telomerase activity but protects from apoptosis

Human telomerase reverse transcriptase (hTERT; the catalytic protein subunit of telomerase) is subjected to numerous alternative splicing events, but the regulation and function of these splice variants is obscure. Full-length hTERT includes conserved domains that encode reverse transcriptase activity, RNA binding, and other functions. The major splice variant termed α+β- or β-deletion is highly expressed in stem and cancer cells, where it codes for a truncated protein lacking most of the reverse transcriptase domain but retaining the known RNA-binding motifs. In a breast cancer cell panel, we found that β-deletion was the hTERT transcript that was most highly expressed. Splicing of this transcript was controlled by the splice regulators SRSF11, HNRNPH2, and HNRNPL, and the β-deletion transcript variant was associated with polyribosomes in cells. When ectopically overexpressed, β-deletion protein competed for binding to telomerase RNA (hTR/TERC), thereby inhibiting endogenous telomerase activity. Overexpressed β-deletion protein localized to the nucleus and mitochondria and protected breast cancer cells from cisplatin-induced apoptosis. Our results reveal that a major hTERT splice variant can confer a growth advantage to cancer cells independent of telomere maintenance, suggesting that hTERT makes multiple contributions to cancer pathophysiology.

Cytomegalovirus is associated with reduced telomerase activity in the Whitehall II cohort

Telomere length and telomerase activity have received increased attention as markers of cellular aging, but the determinants of inter-individual variation in these markers are incompletely understood. Cytomegalovirus (CMV) infection may be particularly important for telomere and telomerase dynamics due to its dramatic impact on peripheral blood lymphocyte composition, i.e., increasing the number and proportions of highly differentiated T cells that are characterized by shorter telomere length (TL) and lowered telomerase activity (TA). However, the possible relationship between CMV infection and leukocyte TL and TA has not been well-examined in vivo. This study examined the associations of CMV seropositivity and CMV IgG antibodies with leukocyte (TL) and (TA) in a sample of 434 healthy individuals (ages 53-76) from the Whitehall II cohort. Positive CMV serostatus was significantly associated with lower TA among women, and higher CMV IgG antibody levels were associated with lower TA in the overall sample. However, neither CMV seropositivity nor CMV IgG antibody levels (reflecting subclinical reactivation) among the seropositive were significantly associated with TL. These associations were robust to adjustment for age, employment grade, BMI, and smoking status. The results demonstrate that CMV seropositivity and subclinical reactivation predict lower TA. Future longitudinal studies should test whether the association of CMV with lower TA contributes to accelerated telomere shortening over time.

Visualization of actin filaments and monomers in somatic cell nuclei

Fluorescent nuclear actin reporters are used to determine the distribution of nuclear actin in live somatic cells and evaluate its potential functions. They reveal distinct monomeric and filamentous actin populations in nuclei of live somatic cells and implicate nuclear actin in mRNA processing and organization of the nucleoplasm.

In addition to its long-studied presence in the cytoplasm, actin is also found in the nuclei of eukaryotic cells. The function and form (monomer, filament, or noncanonical oligomer) of nuclear actin are hotly debated, and its localization and dynamics are largely unknown. To determine the distribution of nuclear actin in live somatic cells and evaluate its potential functions, we constructed and validated fluorescent nuclear actin probes. Monomeric actin probes concentrate in nuclear speckles, suggesting an interaction of monomers with RNA-processing factors. Filamentous actin probes recognize discrete structures with submicron lengths that are excluded from chromatin-rich regions. In time-lapse movies, these actin filament structures exhibit one of two types of mobility: 1) diffusive, with an average diffusion coefficient of 0.06–0.08 μm²/s, or (2) subdiffusive, with a mobility coefficient of 0.015 μm²/s. Individual filament trajectories exhibit features of particles moving within a viscoelastic mesh. The small size of nuclear actin filaments is inconsistent with a role in micron-scale intranuclear transport, and their localization suggests that they do not participate directly in chromatin-based processes. Our results instead suggest that actin filaments form part of a large, viscoelastic structure in the nucleoplasm and may act as scaffolds that help organize nuclear contents.

Accelerated cell aging in female APOE-ε4 carriers: implications for hormone therapy use

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.

Maternal psychosocial stress during pregnancy is associated with newborn leukocyte telomere length

OBJECTIVE

In adults, one of the major determinants of leukocyte telomere length (LTL), a predictor of age-related diseases and mortality, is cumulative psychosocial stress exposure. More recently we reported that exposure to maternal psychosocial stress during intrauterine life is associated with LTL in young adulthood. The objective of the present study was to determine how early in life this effect of stress on LTL is apparent by quantifying the association of maternal psychosocial stress during pregnancy with newborn telomere length.

STUDY DESIGN

In a prospective study of N = 27 mother-newborn dyads maternal pregnancy-specific stress was assessed in early gestation and cord blood peripheral blood mononuclear cells were subsequently collected and analyzed for LTL measurement.

RESULTS

After accounting for the effects of potential determinants of newborn LTL (gestational age at birth, weight, sex, and exposure to antepartum obstetric complications), there was a significant, independent, linear effect of pregnancy-specific stress on newborn LTL that accounted for 25% of the variance in adjusted LTL (β = -0.099; P = .04).

CONCLUSION

Our finding provides the first preliminary evidence in human beings that maternal psychological stress during pregnancy may exert a "programming" effect on the developing telomere biology system that is already apparent at birth, as reflected by the setting of newborn LTL.

Chronic stress elevates telomerase activity in rats

The enzyme telomerase lengthens telomeres-protective structures containing repetitive DNA sequences at chromosome ends. Telomere shortening is associated with diseases of ageing in mammals. Chronic stress has been related to shorter immune-cell telomeres, but telomerase activity under stress may be low, permitting telomere loss, or high, partially attenuating it. We developed an experimental model to examine the impacts of extended unpredictable stress on telomerase activity in male rats. Telomerase activity was 54 per cent higher in stressed rats than in controls, and associated with stress-related physiological and behavioural outcomes. This significant increase suggests a potential mechanism for resilience to stress-related replicative senescence.

The telomere syndromes

There has been mounting evidence of a causal role for telomere dysfunction in a number of degenerative disorders. Their manifestations encompass common disease states such as idiopathic pulmonary fibrosis and bone marrow failure. Although these disorders seem to be clinically diverse, collectively they comprise a single syndrome spectrum defined by the short telomere defect. Here we review the manifestations and unique genetics of telomere syndromes. We also discuss their underlying molecular mechanisms and significance for understanding common age-related disease processes.

The telomere syndromes

There has been mounting evidence of a causal role for telomere dysfunction in a number of degenerative disorders. Their manifestations encompass common disease states such as idiopathic pulmonary fibrosis and bone marrow failure. Although these disorders seem to be clinically diverse, collectively they comprise a single syndrome spectrum defined by the short telomere defect. Here we review the manifestations and unique genetics of telomere syndromes. We also discuss their underlying molecular mechanisms and significance for understanding common age-related disease processes.

Stress appraisals and cellular aging: a key role for anticipatory threat in the relationship between psychological stress and telomere length

Chronic psychological stress is a risk factor for multiple diseases of aging. Accelerated cellular aging as indexed by short telomere length has emerged as a potential common biological mechanism linking various forms of psychological stress and diseases of aging. Stress appraisals determine the degree and type of biological stress responses and altered stress appraisals may be a common psychological mechanism linking psychological stress and diseases of aging. However, no previous studies have examined the relationship between stress appraisals and telomere length. We exposed chronically stressed female caregivers and non-caregiving controls (N=50; M age=62.14±6.10) to a standardized acute laboratory stressor and measured their anticipatory and retrospective threat and challenge appraisals of the stressor. We hypothesized that threat and challenge appraisals would be associated with shorter and longer telomere length respectively, and that chronic caregiving stress would influence telomere length through altered stress appraisals. Higher anticipatory threat appraisals were associated with shorter age-adjusted telomere length (β=-.32, p=.03), but challenge appraisals and retrospective threat appraisals showed no independent association with telomere length. Caregivers reported significantly higher anticipatory (β=-.36, p=.006) and retrospective (β=-.29, p=.03) threat appraisals than controls, but similar challenge appraisals. Although there was no significant main effect of caregiver status on telomere length, caregiving had a significant indirect effect on telomere length through anticipatory threat appraisals. Exaggerated anticipatory threat appraisals may be a common and modifiable psychological mechanism of psychological stress effects on cellular aging.

Resting leukocyte telomerase activity is elevated in major depression and predicts treatment response

Telomeres are DNA-protein complexes that cap linear DNA strands, protecting DNA from damage. When telomeres critically shorten, cells become susceptible to senescence and apoptosis. Telomerase, a cellular ribonucleoprotein enzyme, rebuilds the length of telomeres and promotes cellular viability. Leukocyte telomeres are reportedly shortened in major depression, but telomerase activity in depression has not been previously reported. Further, there are no published reports of the effects of antidepressants on telomerase activity or on the relationship between telomerase activity and antidepressant response. Peripheral blood mononuclear cell (PBMC) telomerase activity was assessed in 20 medication-free depressed individuals and 18 controls. In total, 16 of the depressed individuals were then treated with sertraline in an open-label manner for 8 weeks, and PBMC telomerase activity was reassessed in 15 of these individuals after treatment. Pre- and post-treatment symptom severity was rated with the Hamilton Depression Rating Scale. All analyses were corrected for age and sex. Pre-treatment telomerase activity was significantly elevated in the depressed individuals compared with the controls (P=0.007) and was directly correlated with depression ratings (P<0.05) across all subjects. In the depressed group, individuals with relatively lower pre-treatment telomerase activity and with relatively greater increase in telomerase activity during treatment, showed superior antidepressant responses (P<0.05 and P<0.005, respectively). This is the first report characterizing telomerase activity in depressed individuals. PBMC telomerase activity might reflect a novel aspect of depressive pathophysiology and might represent a novel biomarker of antidepressant responsiveness.