Changes of telomere length with aging

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

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

Association of longer telomere length in cancer cells and cancer-associated fibroblasts with worse prognosis

BACKGROUND

Telomere dysfunction has been reported to be directly involved in carcinogenesis owing to chromosomal instability and immortalization; however, the clinicopathological significance of telomeres remains controversial. We have shown that telomere shortening occurs in normal-appearing duct cells at initiation and then continues during the progression of pancreatic cancer. In this study, we determined the clinicopathological and prognostic value of telomere length (TL) in cancer progression.

METHODS

TL in both cancer cells and cancer-associated fibroblasts (CAFs) was analyzed by high-throughput quantitative fluorescence in situ hybridization using a previously reported cohort comprising 1434 cases of adenocarcinoma (ADC), squamous cell carcinoma (SCC), adenosquamous carcinoma, hepatocellular carcinoma, and renal cell carcinoma (RCC), which are known cancers with a statistically significantly low incidence of alternative lengthening of telomeres. Cases were divided into 2 groups as follows: longer and shorter telomeres, according to the median TL of cancer cells and CAFs. The statistical significance of TL in cancer cells and CAFs on clinicopathological characteristics and prognosis was analyzed.

RESULTS

There was a close association between TL in cancer cells and CAFs. Longer telomeres in cancer cells and CAFs were associated with aggressive features such as advanced stage, high mitosis score and nuclear score, poorly differentiated cancer, and desmoplastic stroma in ADC. Furthermore, a longer TL was an independent prognostic factor for ADC, SCC, and RCC.

CONCLUSIONS

Longer telomeres are associated with worse prognosis in ADC, SCC, and RCC. Thus, TL is a novel biomarker for the diagnosis of aggressive cancers with poor prognoses.

Bioactive Oligopeptides from Ginseng (Panax ginseng Meyer) Suppress Oxidative Stress-Induced Senescence in Fibroblasts via NAD+/SIRT1/PGC-1α Signaling Pathway

The physicochemical properties and multiple bioactive effects of ginseng oligopeptides (GOPs), plant-derived small molecule bioactive peptides, suggest a positive influence on health span and longevity. Given this, cellular senescence is the initiating factor and key mechanism of aging in the organism, and thus the current study sought to explore the effects of GOPs on H₂O₂-induced cellular senescence and its potential mechanisms. Senescence was induced in mouse embryonic fibroblasts NIH/3T3 by 4 h of exposure to 200 µM H₂O₂ and confirmed using CCK-8 assay and Western blot analyses of p16^INK4A and p21^Waf1/Cip1 after 24 h of growth medium administration with or without GOPs supplementation (25, 50, and 100 µg/mL). We found that GOPs delayed oxidative stress-induced NIH/3T3 senescence by inhibiting the G1 phase arrest, increasing DNA synthesis in the S phase, decreasing the relative protein expression of p16^INK4A and p21^Waf1/Cip1, promoting cell viability, protecting DNA, and enhancing telomerase (TE) activity. Further investigation revealed that the increase in antioxidative capacity and anti-inflammation capacity might form the basis for the retarding of the senescence effects of GOPs. Furthermore, GOPs supplementation significantly improved mitochondrial function and mitochondrial biogenesis via the NAD⁺/SIRT1/PGC-1𝛼 pathway. These findings indicate that GOPs may have a positive effect on health span and lifespan extension via combating cellular senescence, oxidative stress, and inflammation, as well as modulating longevity regulating pathway NAD⁺/SIRT1/PGC-1𝛼.

Is Human Aging a Form of Phenoptosis?

A much debated question is whether aging is the cumulative consequence of degenerative factors insufficiently opposed by natural selection, or, on the contrary, an ordered process, genetically determined and regulated, modeled by natural selection, and for which the definition of phenoptotic phenomenon would be entirely appropriate. In this review, theoretical arguments and empirical data about the two hypotheses are exposed, with more evidence in support of the thesis of aging as a form of phenoptosis. However, as the thesis of aging as an adaptive and programmed phenomenon necessarily requires the existence of specific mechanisms that determine to age, such as the subtelomere-telomere theory proposed for this purpose, the evidence supporting the mechanisms described by this theory is reported. In particular, it is highlighted that the recent interpretation of the role of TERRA sequences in the context of subtelomere-telomere theory is a fundamental point in supporting the hypothesized mechanisms. Furthermore, some characteristics of the mechanisms proposed by the theory, such as epigenetic modifications in aging, gradual cell senescence, cell senescence, limits in cell duplications, and fixed size of the telomeric heterochromatin hood, are exposed in their compatibility with both the thesis of aging as phenoptotic phenomenon and the opposite thesis. In short, aging as a form of phenoptosis appears a scientifically sound hypothesis while the opposite thesis should clarify the meaning of various phenomena that appear to invalidate it.

Telomere Length and Risk of Incident Fracture and Arthroplasty: Findings From UK Biobank

We investigated independent associations between telomere length and risk of fracture and arthroplasty in UK Biobank participants. Leukocyte telomere length (LTL) was measured in baseline samples using a validated polymerase chain reaction (PCR) method. We used, in men and women separately, Cox proportional hazards models to calculate the hazard ratio (HR) for incident fracture (any, osteoporotic) or arthroplasty (hip or knee) over 1,186,410 person-years of follow-up. Covariates included age, white cell count, ethnicity, smoking, alcohol, physical activity, and menopause (women). In further analyses we adjusted for either estimated bone mineral density (eBMD) from heel quantitative ultrasound, handgrip strength, gait speed, total fat mass (bioimpedance), or blood biomarkers, all measured at baseline (2006-2010). We studied 59,500 women and 51,895 men, mean ± standard deviation (SD) age 56.4 ± 8.0 and 57.0 ± 8.3 years, respectively. During follow-up there were 5619 fractures; 5285 hip and 4261 knee arthroplasties. In confounder-adjusted models, longer LTL was associated with reduced risk of incident knee arthroplasty in both men (HR/SD 0.93; 95% confidence interval [CI], 0.88-0.97) and women (0.92; 95% CI, 0.88-0.96), and hip arthroplasty in men (0.91; 95% CI, 0.87-0.95), but not women (0.98; 95% CI, 0.94-1.01). Longer LTL was weakly associated with reduced risk of any incident fracture in women (HR/SD 0.96; 95% CI, 0.93-1.00) with less evidence in men (0.98; 95% CI, 0.93-1.02). Associations with incident outcomes were not materially altered by adjustment for heel eBMD, grip strength, gait speed, fat mass, or blood biomarker measures. In this, the largest study to date, longer LTL was associated with lower risk of incident knee or hip arthroplasty, but only weakly associated with lower risk of fracture. The relative risks were low at a population level, but our findings suggest that common factors acting on the myeloid and musculoskeletal systems might influence later life musculoskeletal outcomes. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Adverse and traumatic exposures, posttraumatic stress disorder, telomere length, and hair cortisol – Exploring associations in a high-risk sample of young adult residential care leavers

Background

Childhood adversities (CAs), potentially traumatic exposures (PTEs), and posttraumatic stress disorder (PTSD) are known to increase the risk for poor health outcomes, including diseases of aging and early mortality. Telomere length (TL) and hair cortisol concentrations (HCC) are biomarkers known to be associated with CA and PTEs, and PTSD, but there is considerable heterogeneity in findings.

Objectives

This study aims to investigate the association of CAs, PTEs, and PTSD with TL and HCC in a high-risk sample of young adults who were previously placed in youth residential care institutions throughout Switzerland.

Method

Our sample includes 130 participants (30.8% women, M _Age = 26.5 ± 3.7 years) with previous youth residential care placements (M_Placements= 3.9). CAs and PTEs, as well as PTSD, were assessed with self-reported questionnaires and semi-structured clinical interviews. Immune cell TL was measured with quantitative polymerase chain reaction (qPCR) in whole blood. Hair samples were collected for HCC measurement and assayed with high-sensitivity ELISA. Multivariate regression models were fitted to describe the associations between CAs, PTEs, and PTSD with TL and HCC, adjusting for covariates.

Results

In our high-risk sample, a higher burden of CAs, PTEs, Criterion A trauma, and PTSD was associated with longer TL. PTEs, Criterion A trauma, and PTSD were associated with lower HCC, however no significant associations between CAs and HCC were found. The magnitude of these effects varied depending on the dimensional or categorical nature of the stress-phenotype and the specific measure used.

Conclusions

Our findings are in contrast with many, but not all, previous studies of associations between adversity and both TL and HCC. For instance, our findings are in line with other studies that find a state of hypocortisolism in PTSD. Better measurement of adversities and trauma, multisystem biomarker approaches, and more research in larger high-risk samples at the upper end of the adversity-continuum is warranted.

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In this high-risk sample,childhood adversities, potential traumatic exposures, criterion A trauma, or posttraumatic stress disorder (PTSD) was associated with longer telomere length (TL).

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Potentially traumatic exposures, criterion A trauma, and PTSD were associated with lower hair cortisol concentrations.

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The magnitude of these effects varied depending on the dimensional or categorical nature of the stress-phenotype and the specific measure used.

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Hypocortisolism might explain findings of longer TL in participants with cumulated adverse and traumatic exposures.

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Research in high-risk populations is strongly needed as results across the entire spectrum of adversity exposures may not generalize to the top end of the spectrum.

Higher hair cortisol concentrations associated with shorter leukocyte telomere length in high-risk young adults

Chronic stress is associated with accelerated biological aging as indexed by short age-adjusted leukocyte telomere length (LTL). Exploring links of biological stress responses with LTL has proved challenging due to the lack of biological measures of chronic psychological stress. Hair cortisol concentration (HCC) has emerged as a measure of chronic hypothalamic pituitary adrenal (HPA) axis activation, allowing the examination of relationships between aggregate cortisol concentrations over time and LTL. Our sample includes 92 participants (38% women, M_age = 26 ± 3.7 years) from a high-risk sample of young adults with previous residential care placements. Two cm hair was collected for HCC, reflecting approximately eight weeks of cortisol secretion. LTL was measured with quantitative polymerase chain reaction (qPCR) in whole blood samples. All samples for LTL were run in triplicate and assayed twice. Linear and polynomial regression models were used to describe the association between HCC and LTL, adjusting for age and sex. HCC and LTL showed negative associations (std. ß = − 0.67, 95% CI [− 0.83, − 0.52], p < .001) in age- and sex-adjusted analyses, indicating that higher HCCs are associated with shorter LTL. Using polynomial regression, we found a curvilinear relationship indicating a stronger negative association at lower cortisol concentrations. Higher HCCs were associated with shorter LTL, supporting the hypothesized involvement of prolonged cortisol secretion in telomere attrition. Thus, HCC may prove useful as a biological indicator of chronic stress associated with aging-related processes in samples exposed to high levels of stress.

Normal Aging Induces Changes in the Brain and Neurodegeneration Progress: Review of the Structural, Biochemical, Metabolic, Cellular, and Molecular Changes

Aging is accompanied by many changes in brain and contributes to progressive cognitive decline. In contrast to pathological changes in brain, normal aging brain changes have relatively mild but important changes in structural, biochemical and molecular level. Representatively, aging associated brain changes include atrophy of tissues, alteration in neurotransmitters and damage accumulation in cellular environment. These effects have causative link with age associated changes which ultimately results in cognitive decline. Although several evidences were found in normal aging changes of brain, it is not clearly integrated. Figuring out aging related changes in brain is important as aging is the process that everyone goes through, and comprehensive understanding may help to progress further studies. This review clarifies normal aging brain changes in an asymptotic and comprehensive manner, from a gross level to a microscopic and molecular level, and discusses potential approaches to seek the changes with cognitive decline.

Telomere length in patients with osteoarthritis: a systematic review and meta-analysis

BACKGROUND

Telomere length (TL) as a biomarker of aging was associated with many age-related diseases. The relationship between TL and osteoarthritis (OA), the most common form of joint diseases, had been investigated in a number of studies, but with the result inconsistent.

AIMS

The purpose of this study was to systematically evaluate the relationship between TL and OA.

METHODS

Until January 1, 2021, PubMed, Web of Science and Cochrane Library were comprehensively retrieved for relevant literatures. Quality of included literature was assessed using the Newcastle-Ottawa Scale (NOS) assessment scale. The pooled standard mean difference (SMD) with 95% confidence interval (CI) of Leukocytes TL was calculated using random-effect model. Subgroup analysis and meta-regression were used to investigate the potential source of heterogeneity.

RESULTS

Six original studies containing 678 OA patients and 1457 healthy controls were included in this meta-analysis. All six included studies were case-control designed. Pooled results showed that patients with OA had a shorter TL in peripheral blood leukocytes (PBLs) compared with healthy controls, (SMD = - 0.32, 95% CI - 0.57 to - 0.06, Z = - 2.45, P = 0.014). Subgroup and meta-regression analysis showed that sex ratio and body mass index (BMI) were possible sources of heterogeneity. Publication bias was not observed.

CONCLUSION

The TL of PBLs in patients with OA was shorter than that of healthy controls, suggesting that PBLs TL may be closely associated with the pathogenesis and progression of OA.

The characteristics and clinical significance of atypical mitosis in breast cancer

Atypical mitosis is considered a feature of malignancy, however, its significance in breast cancer (BC) remains elusive. Here, we aimed to assess the clinical value of atypical mitoses in BC and to explore their underlying molecular features. Atypical and typical mitotic figures were quantified and correlated with clinicopathological variables in a large cohort of primary BC tissue sections (n = 846) using digitalized hematoxylin and eosin whole-slide images (WSIs). In addition, atypical mitoses were assessed in The Cancer Genome Atlas (TCGA) BC dataset (n = 1032) and were linked to the genetic alterations and pathways. In this study, the median of typical mitoses was 17 per 3 mm² (range 0-120 mitoses), while the median of atypical mitoses was 4 (range 0-103 mitoses). High atypical mitoses were significantly associated with parameters characteristic of aggressive tumor behavior. The total number of mitoses, and a high atypical-to-typical mitoses ratio (>0.27) were associated with poor BC specific survival (BCSS), (p = 0.04 and 0.01, respectively). The atypical-to-typical mitoses ratio dichotomized triple negative-BC (TNBC) patients into two distinct groups in terms of the association with the outcome, while the overall number of mitoses was not. Moreover, TNBC patients with high atypical-to-typical mitoses ratio treated with adjuvant chemotherapy were associated with shorter survival (p = 0.003). Transcriptomic analysis of the TCGA-BRCA cohort dichotomized based on atypical mitoses identified 2494 differentially expressed genes. These included genes linked to pathways involved in chromosomal localization and segregation, centrosome assembly, spindle and microtubule formation, regulation of cell cycle and DNA repair. To conclude, the atypical-to-typical mitoses ratio has prognostic value independent of the overall mitotic count in BC patients and could predict the response to chemotherapy in TNBC.

Is Evidence Supporting the Subtelomere-Telomere Theory of Aging?

The telomere theory tries to explain cellular mechanisms of aging as mainly caused by telomere shortening at each duplication. The subtelomere-telomere theory overcomes various shortcomings of telomere theory by highlighting the essential role of subtelomeric DNA in aging mechanisms. The present work illustrates and deepens the correspondence between assumptions and implications of subtelomere-telomere theory and experimental results. In particular, it is investigated the evidence regarding the relationships between aging and (i) epigenetic modifications; (ii) oxidation and inflammation; (iii) telomere protection; (iv) telomeric heterochromatin hood; (v) gradual cell senescence; (vi) cell senescence; and (vii) organism decline with telomere shortening. The evidence appears broadly in accordance or at least compatible with the description and implications of the subtelomere-telomere theory. In short, phenomena of cellular aging, by which the senescence of the whole organism is determined in various ways, appear substantially dependent on epigenetic modifications regulated by the subtelomere-telomere-telomeric hood-telomerase system. These phenomena appear to be not random, inevitable, and irreversible but rather induced and regulated by genetically determined mechanisms, and modifiable and reversible by appropriate methods. All this supports the thesis that aging is a genetically programmed and regulated phenoptotic phenomenon and is against the opposite thesis of aging as caused by random and inevitable degenerative factors.

Assessment of mitotic activity in breast cancer: revisited in the digital pathology era

The assessment of cell proliferation is a key morphological feature for diagnosing various pathological lesions and predicting their clinical behaviour. Visual assessment of mitotic figures in routine histological sections remains the gold-standard method to evaluate the proliferative activity and grading of cancer. Despite the apparent simplicity of such a well-established method, visual assessment of mitotic figures in breast cancer (BC) remains a challenging task with low concordance among pathologists which can lead to under or overestimation of tumour grade and hence affects management. Guideline recommendations for counting mitoses in BC have been published to standardise methodology and improve concordance; however, the results remain less satisfactory. Alternative approaches such as the use of the proliferation marker Ki67 have been recommended but these did not show better performance in terms of concordance or prognostic stratification. The advent of whole slide image technology has brought the issue of mitotic counting in BC into the light again with more challenges to develop objective criteria for identifying and scoring mitotic figures in digitalised images. Using reliable and reproducible morphological criteria can provide the highest degree of concordance among pathologists and could even benefit the further application of artificial intelligence (AI) in breast pathology, and this relies mainly on the explicit description of these figures. In this review, we highlight the morphology of mitotic figures and their mimickers, address the current caveats in counting mitoses in breast pathology and describe how to strictly apply the morphological criteria for accurate and reliable histological grade and AI models.

Association of accelerated dynamics of telomere sequence loss in peripheral blood leukocytes with incident knee osteoarthritis in Osteoarthritis Initiative cohort

Osteoarthritis (OA) is a chronic degenerative joint disease, being the main cause of laboral inability. Decreased telomere size in peripheral blood leukocytes (PBL) has been correlated with age-related pathologies, like knee OA. In a dynamic approach, telomere-qPCR was performed to evaluate the relative percentage of PBL telomere loss after a 6-year follow-up, in 281 subjects from the prospective osteoarthritis initiative (OAI) cohort. A radiological Kellgren-Lawrence (KL) grade ≥ 2 was indicative of knee OA. Individuals with knee OA at recruitment (n = 144) showed a higher PBL telomere loss after 6 years than those without knee OA at baseline (n = 137; p = 0.018). Moreover, individuals that developed knee OA during the follow-up (n = 39) exhibited a higher telomere loss compared to those that remained without OA (n = 98; p < 0.001). Logistic regression analysis showed that PBLs telomere loss was not significantly associated with knee OA at recruitment, but behaves as an independent risk factor associated with incidence after follow-up (OR: 1.043; p = 0.041), together with maximum KL grade (OR: 3.627; p = 0.011), body mass index-BMI (OR: 1.252; p < 0.001) and WOMAC-index (OR: 1.247; p = 0.021), at recruitment. The telomere decay in PBLs is faster in individuals with incident knee OA, possibly reflecting a systemic-global accelerated aging that enhances the cartilage degeneration.

In vivo biomarkers of structural and functional brain development and aging in humans

Brain aging is a major determinant of aging. Along with the aging population, prevalence of neurodegenerative diseases is increasing, therewith placing economic and social burden on individuals and society. Individual rates of brain aging are shaped by genetics, epigenetics, and prenatal environmental. Biomarkers of biological brain aging are needed to predict individual trajectories of aging and the risk for age-associated neurological impairments for developing early preventive and interventional measures. We review current advances of in vivo biomarkers predicting individual brain age. Telomere length and epigenetic clock, two important biomarkers that are closely related to the mechanistic aging process, have only poor deterministic and predictive accuracy regarding individual brain aging due to their high intra- and interindividual variability. Phenotype-related biomarkers of global cognitive function and brain structure provide a much closer correlation to age at the individual level. During fetal and perinatal life, autonomic activity is a unique functional marker of brain development. The cognitive and structural biomarkers also boast high diagnostic specificity for determining individual risks for neurodegenerative diseases.

Molecular and cellular pathways contributing to brain aging

Aging is the leading risk factor for several age-associated diseases such as neurodegenerative diseases. Understanding the biology of aging mechanisms is essential to the pursuit of brain health. In this regard, brain aging is defined by a gradual decrease in neurophysiological functions, impaired adaptive neuroplasticity, dysregulation of neuronal Ca2+ homeostasis, neuroinflammation, and oxidatively modified molecules and organelles. Numerous pathways lead to brain aging, including increased oxidative stress, inflammation, disturbances in energy metabolism such as deregulated autophagy, mitochondrial dysfunction, and IGF-1, mTOR, ROS, AMPK, SIRTs, and p53 as central modulators of the metabolic control, connecting aging to the pathways, which lead to neurodegenerative disorders. Also, calorie restriction (CR), physical exercise, and mental activities can extend lifespan and increase nervous system resistance to age-associated neurodegenerative diseases. The neuroprotective effect of CR involves increased protection against ROS generation, maintenance of cellular Ca2+ homeostasis, and inhibition of apoptosis. The recent evidence about the modem molecular and cellular methods in neurobiology to brain aging is exhibiting a significant potential in brain cells for adaptation to aging and resistance to neurodegenerative disorders.

Age-related telomere attrition causes aberrant gene expression in sub-telomeric regions

Telomere attrition has been proposed as a biomarker and causal factor in aging. In addition to causing cellular senescence and apoptosis, telomere shortening has been found to affect gene expression in subtelomeric regions. Here, we analyzed the distribution of age-related differentially expressed genes from the GTEx RNA sequencing database of 54 tissue types from 979 human subjects and found significantly more upregulated than downregulated genes in subtelomeric regions as compared to the genome-wide average. Our data demonstrate spatial relationships between telomeres and gene expression in aging.

Relationship Between the Dynamics of Telomere Loss in Peripheral Blood Leukocytes From Knee Osteoarthritis Patients and Mitochondrial DNA Haplogroups

OBJECTIVE

To evaluate the evolution of telomere length from peripheral blood leukocytes (PBLs) in subjects from the Osteoarthritis Initiative (OAI) cohort in relation to the incidence of osteoarthritis (OA), and to explore its possible interactive influence with the mitochondrial DNA (mtDNA) haplogroup.

METHODS

Dynamics of telomere sequence loss were quantified in PBLs from initially healthy individuals (without symptoms or radiological signs), 78 carrying the mtDNA cluster HV, and 47 with cluster JT, from the OAI, during a 72-month follow-up period. The incidence of knee OA during this period (n = 39) was radiographically established when Kellgren-Lawrence (KL) score increased from < 2 at recruitment, to ≥ 2 at the end of 72 months of follow-up. Multivariate analysis using binary logistic regression was performed to assess PBL telomere loss and mtDNA haplogroups as associated risk factors of incidence of knee OA.

RESULTS

Carriers of cluster HV showed knee OA incidence twice that of the JT carriers (n = 30 vs 9). The rate of PBL telomere loss was higher in cluster HV carriers and in individuals with incident knee OA. Multivariate analysis showed that the dynamics of PBL telomere shortening can be a consistent risk marker of knee OA incidence. Subjects with nonincident knee OA showed a slower telomere loss than those with incident knee OA; the difference was more significant in carriers of cluster JT than in HV.

CONCLUSION

An increased rate of telomere loss in PBLs may reflect a systemic accelerated senescence phenotype that could be potentiated by the mitochondrial function, increasing the susceptibility of developing knee OA.

The Dynamic Interplay Between Mast Cells, Aging/Cellular Senescence, and Liver Disease

Mast cells are key players in acute immune responses that are evidenced by degranulation leading to a heightened allergic response. Activation of mast cells can trigger a number of different pathways contributing to metabolic conditions and disease progression. Aging results in irreversible physiological changes affecting all organs, including the liver. The liver undergoes senescence, changes in protein expression, and cell signaling phenotypes during aging, which regulate disease progression. Cellular senescence contributes to the age-related changes. Unsurprisingly, mast cells also undergo age-related changes in number, localization, and activation throughout their lifetime, which adversely affects the etiology and progression of many physiological conditions including liver diseases. In this review, we discuss the role of mast cells during aging, including features of aging (e.g., senescence) in the context of biliary diseases such as primary biliary cholangitis and primary sclerosing cholangitis and nonalcoholic fatty liver disease.

Age relationships with telomere length, body weight and body length in wild dugong (Dugong dugon)

The ability to estimate age and determine the growth status of free-ranging dugongs (Dugong dugon) is vital to providing insight into the basic biology of this endangered species. Currently, age estimation in dugong carcasses relies on counting dentin growth layer groups (GLGs) in tusks, but a disadvantage is they need to be intact. We explored whether measures of telomere length could be used as an alternative approach to age estimation in dugongs given that in other species, telomere length and age are inversely related. In this study, relative telomere length (rTL) was measured by qPCR in skin samples from 24 dugongs of varying ages determined by counts of GLGs. In addition, relationships between age by GLG counts and body weight and length and were examined. Our findings indicate that age estimated by GLGs was negatively correlated with telomere length using the logistic formula with a rate of telomere attrition of approximately 0.036 rTL/year between the ages of 5-20 years. By comparison, both body weight and length were positively correlated with GLG-based age, with growth rates of ~8.8 kg/year for weight and ~3.58 cm/year for length, respectively. After that, growth rates slowed substantially and then plateaued. The results suggest that physical maturity in dugongs occurs at 20 years of age and that measures of rTL might serve as a tool for age estimation in dugongs, living and deceased.

Cardio-metabolic consequences of dietary carbohydrates: reconciling contradictions using nutritional geometry

Carbohydrates are the major source of dietary energy, but their role in health and disease remains controversial. Recent epidemiological evidence suggests that the increased consumption of carbohydrates is associated with obesity and increased risk of mortality and dietary trials show that carbohydrate restriction leads to weight loss and improved glycaemic status in obese and diabetic subjects. In contrast, the diets of populations with long and healthy lifespans (e.g. traditional Okinawans from Japan) are high in carbohydrate and low in protein, and several clinical and preclinical studies have linked low-carbohydrate-high-protein diets with increased mortality risk. In this paper we attempt to reconcile these contradictory findings by moving beyond traditional single-nutrient analyses to consider the interactions between nutrients on health outcomes. We do so using the Geometric Framework (GF), a nutritional modelling platform that explicitly considers the main and interactive effects of multiple nutrients on phenotypic characteristics. Analysis of human data by GF shows that weight loss and improved cardio-metabolic outcomes under carbohydrate restriction derive at least in part from reduced caloric intake due to the concomitantly increased proportion of protein in the diet. This is because, as in many animals, a specific appetite for protein is a major driver of food intake in humans. Conversely, dilution of protein in the diet leverages excess food intake through compensatory feeding for protein ('protein leverage'). When protein is diluted in the diet by readily digestible carbohydrates and fats, as is the case in modern ultra-processed foods, protein leverage results in excess calorie intake, leading to rising levels of obesity and metabolic disease. However, when protein is diluted in the diet by increased quantities of less readily digestible forms of carbohydrate and fibre, energy balance is maintained and health benefits accrue, especially during middle age and early late-life. We argue that other controversies in carbohydrate research can be resolved using the GF methodology in dietary studies.

Association between Leucocyte Telomere Length and Risk of Hearing Loss in the General Population: A Case-Control Study in Zhejiang Province, China

Limited studies have assessed the relation between telomere length and risk of hearing loss; moreover, they have reported equivocal associations. In the first case-control study, the subjects were chosen from the general population of Zhejiang province in order to assess the association between leucocyte telomere length and risk of hearing loss from 2016 to 2018. A total of 817 cases (55.93 ± 8.99 years) and 817 age-, sex- and residential city-matched controls (55.91 ± 9.03 years) were included for analysis. In the multivariable models, individuals in the top quartile of relative telomere length (RTL) had an odds ratio (OR) for hearing loss of 0.53 (95% confidence intervals [CI], 0.38–0.74) compared to those in the bottom quartile, and specifically, the OR was 0.45 (95% CI, 0.28–0.73) in females. In females, the risk of hearing loss decreased by 46% as RTL doubling increased; the standard deviation of RTL was associated with a 29% decrease in hearing loss risk. Additional analysis showed significant difference between participants in the female mild hearing loss group and corresponding controls. These results suggest that telomere length is associated with hearing loss in the general population, particularly in females with mild hearing loss. Telomere length might be a potential predictive biomarker of hearing loss at early stage.

Correlation Between Telomere Attrition of Zona Fasciculata and Adrenal Weight Reduction in Older Men

CONTEXT

Although numerous theories are reported on sex differences in longevity, the underlying biological mechanisms remain unknown. We previously reported that telomere length in the zona reticularis cells of the human adrenal cortex was significantly longer in older than that in younger subjects. However, we could not evaluate sex differences in the telomere lengths.

OBJECTIVE

To compare the telomere lengths of adrenocortical and adrenal medullar cells between men and women from infancy through older adulthood.

METHODS

Adrenal glands of 30 male (aged 0 to 100 years) and 25 female (aged 0 to 104 years) autopsied subjects were retrieved from autopsy files. Using quantitative fluorescence in situ hybridization, relative telomere lengths were determined in the parenchymal cells of the 3 adrenocortical zones and medulla. Age-related changes in the weight of adrenal glands were also investigated.

MAIN RESULTS

Older male subjects (aged 65 years or older) had significantly shorter telomere lengths in zona fasciculata (ZF) cells compared to the corresponding female subjects. In men, older subjects exhibited a significant age-related reduction in adrenal weight; however, no age-related changes in adrenal weight were detected in women.

CONCLUSION

Telomere attrition of ZF cells was correlated with adrenal weight reduction in older men but not in older women, suggesting a decreased number of ZF cells in older men. This may help us understand the possible biological mechanisms of sex difference in longevity of humans.

Leukocyte telomere length and serum polyunsaturated fatty acids, dietary habits, cardiovascular risk factors and features of myocardial infarction in elderly patients

BACKGROUND

Telomeres are non-coding sequences at the end of eukaryote chromosomes, which in complex with associated proteins serve to protect subtelomeric DNA. Telomeres shorten with each cell division, are regarded as a biomarker for aging and have also been suggested to play a role in atherosclerosis and cardiovascular disease (CVD). The aim of the present study was to explore the associations between leukocyte telomere length and serum polyunsaturated fatty acids, diet, cardiovascular risk factors and features of myocardial infarction (MI) in elderly patients.

METHODS

The material is based upon the first 299 included patients in the OMEMI trial, where patients aged 70-82 years of age are randomized to receive omega-3 supplements or corn oil (placebo) after MI. Patients were included 2-8 weeks after the index MI. DNA was extracted from whole blood, and leukocyte telomere length (LTL) was analyzed by qPCR and reported as a number relative to a reference gene. Serum long chain polyunsaturated fatty acid (LCPUFA) content was analyzed by gas chromatography. Diet was evaluated with the validated SmartDiet food frequency questionnaire. Medical records, patient interviews and clinical examination provided previous medical history and anthropometric data. Non-parametric statistical tests were used.

RESULTS

Median (25, 75 percentile) LTL was 0.55 (0.42, 0.72). Patients had a median age of 75 years, 70.2% were male and 45.2% used omega-3 supplements. There was a weak, but significant correlation between LTL and linoleic acid (r = 0.139, p = 0.017), but not with other LCPUFAs. There was a trend towards longer telomeres with a healthier diet, but this did not reach statistical significance (p = 0.073). No associations were found between LTL and CVD risk factors or features of MI.

CONCLUSIONS

In our population of elderly with a recent myocardial infarction LTL was associated with linoleic acid concentrations, but not with other LCPUFAs. Patients with a healthy diet tended to have longer telomeres. The limited associations may be due to age and the narrow age-span in our population. Further studies, designed to detect longitudinal changes should be performed to explore the role of telomeres in cardiovascular aging.

TRIAL REGISTRATION

Clinical trials no. NCT01841944, registration date April 29, 2013.

Cell cycle-dependent and -independent telomere shortening accompanies murine brain aging

Replication-based telomere shortening during lifetime is species- and tissue-specific, however, its impact on healthy aging is unclear. In particular, the contribution of telomere truncation to the aging process of the CNS, where replicative senescence alone fails to explain organ aging due to low to absent mitotic activity of intrinsic populations, is undefined. Here, we assessed changes in relative telomere length in non-replicative and replicative neural brain populations and telomerase activity as a function of aging in C57BL/6 mice. Telomeres in neural cells and sub-selected neurons shortened with aging in a cell cycle-dependent and -independent manner, with preponderance in replicative moieties, implying that proliferation accelerates, but is not prerequisite for telomere shortening. Consistent with this telomere erosion, telomerase activity and nuclear TERT protein were not induced with aging. Knockdown of the Rela subunit of NF-κB, which controls both telomerase enzyme and subcellular TERT protein allocation, did also not influence telomerase activity or telomere length, in spite of its naive up-regulation selectively under aging conditions. We conclude that telomere instability is intrinsic to physiological brain aging beyond cell replication, and appears to occur independently of a functional interplay with NF-κB, but rather as a failure to induce or relocate telomerase.

The protective function of non-coding DNA in DNA damage accumulation with age and its roles in age-related diseases

Aging is a progressive decline of physiological function in tissue and organ accompanying both accumulation of DNA damage and reduction of non-coding DNA. Peripheral non-coding DNA/heterochromatin has been proposed to protect the genome and centrally-located protein-coding sequences in soma and male germ cells against radiation and the invasion of exogenous nucleic acids. Therefore, this review summarizes the reduction of non-coding DNA/heterochromatin (including telomeric DNA and rDNA) and DNA damage accumulation during normal physiological aging and in various aging-related diseases. Based on analysis of data, it is found that DNA damage accumulation is roughly negatively correlated with the reduction of non-coding DNA and therefore speculated that DNA damage accumulation is likely due to the reduction of non-coding DNA protection in genome defense during aging. Therefore, it is proposed here that means to increase the total amount of non-coding DNA and/or heterochromatin prior to the onset of these diseases could potentially better protect the genome and protein-coding DNA, reduce the incidence of aging-related diseases, and thus lead to better health during aging.

Adverse Childhood Experiences and Telomere Length a Look Into the Heterogeneity of Findings-A Narrative Review

Background: Adverse childhood experiences (ACEs) have been associated with poor mental and somatic health. Accumulating evidence indicates that accelerated biological aging-indexed by altered telomere-related markers-may contribute to associations between ACEs and negative long-term health outcomes. Telomeres are repeated, non-coding deoxyribonucleic acid (DNA) sequences at the end of chromosomes. Telomeres shorten during repeated cell divisions over time and are being used as a marker of biological aging. Objectives: The aim of the current paper is to review the literature on the relationship between ACEs and telomere length (TL), with a specific focus on how the heterogeneity of sample and ACEs characteristics lead to varying associations between ACEs and TL. Methods: Multiple databases were searched for relevant English peer-reviewed articles. Thirty-eight papers were found to be eligible for inclusion in the current review. Results: Overall, the studies indicated a negative association between ACEs and TL, although many papers presented mixed findings and about a quarter of eligible studies found no association. Studies with smaller sample sizes more often reported significant associations than studies with larger samples. Also, studies reporting on non-clinical and younger samples more often found associations between ACEs and TL compared to studies with clinical and older samples. Reviewing the included studies based on the "Stressor Exposure Characteristics" recently proposed by Epel et al. (2018) revealed a lack of detailed information regarding ACEs characteristics in many studies. Conclusion: Overall, it is difficult to achieve firm conclusions about associations of ACEs with TL due to the heterogeneity of study and ACE characteristics and the heterogeneity in reported findings. The field would benefit from more detailed descriptions of study samples and measurement of ACEs.

Telomere biology and age-related diseases

Telomeres are the protective end caps of chromosomes and shorten with every cell division. Telomere length has been proposed as a biomarker of biological age and a risk factor for age-related diseases. Epidemiologic studies show an association between leukocyte telomere length (LTL) and mortality. There is solid evidence that links LTL with cardiovascular disease. Short telomeres promote atherosclerosis and impair the repair of vascular lesions. Alzheimer's disease patients have also a reduced LTL. Telomeres measured in tumor tissue from breast, colon and prostate are shorter than in healthy tissue from the same organ and the same patient. In healthy tissue directly adjacent to these tumors, telomeres are also shorter than in cells that are more distant from the cancerous lesion. A reduced telomere length in cancer tissue from breast, colon and prostate is associated with an advanced disease state at diagnosis, faster disease progression and poorer survival. By contrast, results regarding LTL and cancer are inconsistent. Furthermore, the majority of studies did not find significant associations between LTL, bone mineral density (BMD) and osteoporosis. The present manuscript gives an overview about our current understanding of telomere biology and reviews existing knowledge regarding the relationship between telomere length and age-related diseases.

Adult Cardiac Stem Cell Aging: A Reversible Stochastic Phenomenon?

Aging is by far the dominant risk factor for the development of cardiovascular diseases, whose prevalence dramatically increases with increasing age reaching epidemic proportions. In the elderly, pathologic cellular and molecular changes in cardiac tissue homeostasis and response to injury result in progressive deteriorations in the structure and function of the heart. Although the phenotypes of cardiac aging have been the subject of intense study, the recent discovery that cardiac homeostasis during mammalian lifespan is maintained and regulated by regenerative events associated with endogenous cardiac stem cell (CSC) activation has produced a crucial reconsideration of the biology of the adult and aged mammalian myocardium. The classical notion of the adult heart as a static organ, in terms of cell turnover and renewal, has now been replaced by a dynamic model in which cardiac cells continuously die and are then replaced by CSC progeny differentiation. However, CSCs are not immortal. They undergo cellular senescence characterized by increased ROS production and oxidative stress and loss of telomere/telomerase integrity in response to a variety of physiological and pathological demands with aging. Nevertheless, the old myocardium preserves an endogenous functionally competent CSC cohort which appears to be resistant to the senescent phenotype occurring with aging. The latter envisions the phenomenon of CSC ageing as a result of a stochastic and therefore reversible cell autonomous process. However, CSC aging could be a programmed cell cycle-dependent process, which affects all or most of the endogenous CSC population. The latter would infer that the loss of CSC regenerative capacity with aging is an inevitable phenomenon that cannot be rescued by stimulating their growth, which would only speed their progressive exhaustion. The resolution of these two biological views will be crucial to design and develop effective CSC-based interventions to counteract cardiac aging not only improving health span of the elderly but also extending lifespan by delaying cardiovascular disease-related deaths.

Novel biomolecules of ageing, sex differences and potential underlying mechanisms of telomere shortening in coronary artery disease

Telomere length (TL), growth differentiate factor (GDF)11, insulin growth factor (IGF)1, sirtuin (SIRT)1 and inflammatory processes have been related to ageing and age-related diseases, like coronary artery disease (CAD). We aimed to investigate the associations between leukocyte TLs (LTLs), chronological age, sex and comorbidities in CAD patients. Any covariations between LTL, GDF11, IGF1, SIRT-1 and pro-inflammatory cytokines were further assessed.

METHODS

In 300 patients with stable CAD (age 36-81 years, 20% females), DNA and RNA were isolated from whole blood for PCR analysis and relative quantification of LTLs and gene-expression of GDF11, IGF1,SIRT1, IL-12, IL-18 and IFNƴ, respectively. Serum was prepared for the analyses of circulating IL-18, IL-12, IL-6 and TNFα.

RESULTS

Patients with previous myocardial infarction (MI) presented with 20% shorter LTLs vs. patients without (p = 0.019) indicating LTLs to be of importance for CAD severity. The observation however, was only observed in men (p = 0.009, n = 115), in which the upper LTL quartile associated with 64% lower frequency of previous MI compared to quartile 1-3 (p = 0.005, adjusted). LTLs were not differently distributed according to sex or comorbidities such as hypertension, diabetes type 2 and metabolic syndrome. LTLs and GDF11 were inversely correlated to age (r = -0.17; p = 0.007 and r = -0.16; p = 0.010, respectively), however, separated in gender, LTL only in women (r = -0.37) and GDF11 only in men (r = -0.19) (p = 0.006, both). GDF11 and SIRT1 were strongly inter-correlated (r = 0.56, p ≤ 0.001), suggesting common upstream regulators. LTLs were moderately correlated to GDF11 and SIRT1 in overweight women (BMI ≥ 25 kg/m²) (r = 0.41; p = 0.027 and 0.43; p = 0.020, respectively), which may reflect common life-style influences on LTLs and these markers. In all women, we observed further that the highest LTL quartile associated with higher GDF11 and SIRT expression and lower circulating levels of IL-12, IL-18 and TNFα, as compared to quartile 1, which may indicate lifestyle influences on female LTLs. In men, the highest LTL quartile associated with lower IFNƴ expression and lower circulating TNFα. Overall, the results indicate an association between chronic low-grade inflammation and LTLs.

CONCLUSIONS

Shorter LTLs in CAD patients with previously suffered MI may indicate telomere attrition as part of its pathophysiology in men. The inverse association between LTLs and age exclusively in women underpins the previously reported decline in attrition rate in men with increasing age. As elevated GDF11 and SIRT1 along with attenuated pro-inflammatory cytokines seem to positively affect LTL in women, we hypothesize a potential sex-dimorphism in LTL regulation, which may implicate sex- adjusted health-preventive therapies.

Shorter telomeres associated with high doses of glucocorticoids: the link to increased mortality?

OBJECTIVE

Patients with non-functioning pituitary adenomas exhibit high morbidity and mortality rates. Growth hormone deficiency and high doses of glucocorticoid substitution therapy have been identified as corresponding risk factors. Interestingly, high levels of endogenous cortisol in, e.g., patients with post-traumatic stress disorder or patients with Cushing's disease have been linked to shorter telomere length. Telomeres are noncoding DNA regions located at the end of chromosomes consisting of repetitive DNA sequences which shorten with ageing and hereby determine cell survival. Therefore, telomere length can serve as a predictor for the onset of disease and mortality in some endocrine disorders (e.g., Cushing's disease).

DESIGN/METHODS

We examine telomere length from blood in patients (n = 115) with non-functioning pituitary adenomas (NFPA) in a cross-sectional case control (n = 106, age-, gender- matched) study using qPCR. Linear regression models were used to identify independent predictors of telomere length.

RESULTS

We show that patients with NFPA exhibited shorter telomeres than controls. No significant association of indices of growth hormone deficiency (IGF-1-level-SDS, years of unsubstituted growth hormone deficiency etc.) with telomere length was detected. Interestingly, linear regression analysis showed that hydrocortisone replacement dosage in patients with adrenal insufficiency (n = 52) was a significant predictor for shorter telomere length (β = 0.377; p = 0.018) independent of potential confounders. Median split analysis revealed that higher hydrocortisone intake (> 20 mg) was associated with significantly shorter telomeres.

CONCLUSION

These observations strengthen the importance of adjusted glucocorticoid treatment in NFPA patients with respect to morbidity and mortality rates.

A Rare Variant P507L in TPP1 Interrupts TPP1-TIN2 Interaction, Influences Telomere Length, and Confers Colorectal Cancer Risk in Chinese Population

Background: Telomere dysfunction triggers cellular senescence and constitutes a driving force for cancer initiation. Genetic variants in genes involved in telomere maintenance may contribute to colorectal cancer susceptibility.Methods: In this study, we firstly captured germline mutations in 192 patients with colorectal cancer by sequencing the coding regions of 13 core components implicated in telomere biology. Five potential functional variants were then genotyped and assessed in a case-control set with 3,761 colorectal cancer cases and 3,839 healthy controls. The promising association was replicated in additional 6,765 cases and 6,906 controls. Functional experiments were used to further clarify the potential function of the significant variant and uncover the underlying mechanism in colorectal cancer development.Results: The two-stage association studies showed that a rare missense variant rs149418249 (c.C1520T and p.P507L) in the 11th exon of TPP1 (also known as ACD, gene ID 65057) was significantly associated with colorectal cancer risk with the ORs being 2.90 [95% confidence interval (CI), 1.04-8.07; P = 0.041], 2.50 (95% CI, 1.04-6.04; P = 0.042), and 2.66 (95% CI, 1.36-5.18; P = 0.004) in discovery, replication, and the combined samples, respectively. Further functional annotation indicated that the TPP1 P507L substitution interrupted TPP1-TIN2 interaction, impaired telomerase processivity, and shortened telomere length, which subsequently facilitated cell proliferation and promoted colorectal cancer development.Conclusions: A rare variant P507L in TPP1 confers increased risk of colorectal cancer through interrupting TPP1-TIN2 interaction, impairing telomerase processivity, and shrinking telomere length.Impact: These findings emphasize the important role of telomere dysfunction in colorectal cancer development, and provide new insights about the prevention of this type of cancer. Cancer Epidemiol Biomarkers Prev; 27(9); 1029-35. ©2018 AACR.

Telomere length of gallbladder epithelium is shortened in patients with congenital biliary dilatation: measurement by quantitative fluorescence in situ hybridization

BACKGROUND

Congenital biliary dilatation (CBD) is a congenital malformation involving both dilatation of the extrahepatic bile duct and pancreaticobiliary maljunction. Persistent reflux of pancreatic juice injures the biliary tract mucosa, resulting in chronic inflammation and higher rates of carcinogenesis in the biliary tract, including the gallbladder. Telomeres are repetitive DNA sequences located at the ends of chromosomes. Chromosomal instability due to telomere dysfunction plays an important role in the carcinogenesis of many organs. This study was performed to determine whether excessive shortening of telomeres occurs in the gallbladder mucosa of patients with CBD.

METHODS

Resected gallbladders were obtained from 17 patients with CBD, ten patients with cholecystolithiasis without pancreatic juice reflux, and 17 patients with normal gallbladders (controls) (median age of each group of patients: 37, 50, and 53 years, respectively). The telomere lengths of the gallbladder epithelium were measured by quantitative fluorescence in situ hybridization using tissue sections, and the normalized telomere-to-centromere ratio (NTCR) was calculated.

RESULTS

The NTCRs in the CBD, cholecystolithiasis, and control groups were 1.24 [interquartile range (IQR) 1.125-1.52], 1.96 (IQR 1.56-2.295), and 1.77 (IQR 1.48-2.53), respectively. The NTCR in the CBD group was significantly smaller than that in the cholecystolithiasis and control groups (p = 0.003 and 0.004, respectively), even in young patients.

CONCLUSIONS

Our findings indicate that telomere shortening in the gallbladder mucosa plays an important role in the process of carcinogenesis in patients with CBD. These results support the recommendation of established guidelines for prophylactic surgery in patients with CBD because CBD is a premalignant condition with excessive telomere shortening.

Telomeres: Implications for Cancer Development

Telomeres facilitate the protection of natural ends of chromosomes from constitutive exposure to the DNA damage response (DDR). This is most likely achieved by a lariat structure that hides the linear telomeric DNA through protein-protein and protein-DNA interactions. The telomere shortening associated with DNA replication in the absence of a compensatory mechanism culminates in unmasked telomeres. Then, the subsequent activation of the DDR will define the fate of cells according to the functionality of cell cycle checkpoints. Dysfunctional telomeres can suppress cancer development by engaging replicative senescence or apoptotic pathways, but they can also promote tumour initiation. Studies in telomere dynamics and karyotype analysis underpin telomere crisis as a key event driving genomic instability. Significant attainment of telomerase or alternative lengthening of telomeres (ALT)-pathway to maintain telomere length may be permissive and required for clonal evolution of genomically-unstable cells during progression to malignancy. We summarise current knowledge of the role of telomeres in the maintenance of chromosomal stability and carcinogenesis.

Stabilization of Telomere G-Quadruplexes Interferes with Human Herpesvirus 6A Chromosomal Integration

Human herpesviruses 6A and 6B (HHV-6A/B) can integrate their genomes into the telomeres of human chromosomes using a mechanism that remains poorly understood. To achieve a better understanding of the HHV-6A/B integration mechanism, we made use of BRACO-19, a compound that stabilizes G-quadruplex secondary structures and prevents telomere elongation by the telomerase complex. First, we analyzed the folding of telomeric sequences into G-quadruplex structures and their binding to BRACO-19 using G-quadruplex-specific antibodies and surface plasmon resonance. Circular dichroism studies indicate that BRACO-19 modifies the conformation and greatly stabilizes the G-quadruplexes formed in G-rich telomeric DNA. Subsequently we assessed the effects of BRACO-19 on the HHV-6A initial phase of infection. Our results indicate that BRACO-19 does not affect entry of HHV-6A DNA into cells. We next investigated if stabilization of G-quadruplexes by BRACO-19 affected HHV-6A's ability to integrate its genome into host chromosomes. Incubation of telomerase-expressing cells with BRACO-19, such as HeLa and MCF-7, caused a significant reduction in the HHV-6A integration frequency (P < 0.002); in contrast, BRACO-19 had no effect on HHV-6 integration frequency in U2OS cells that lack telomerase activity and elongate their telomeres through alternative lengthening mechanisms. Our data suggest that the fluidity of telomeres is important for efficient chromosomal integration of HHV-6A and that interference with telomerase activity negatively affects the generation of cellular clones containing integrated HHV-6A.IMPORTANCE HHV-6A/B can integrate their genomes into the telomeres of infected cells. Telomeres consist of repeated hexanucleotides (TTAGGG) of various lengths (up to several kilobases) and end with a single-stranded 3' extension. To avoid recognition and induce a DNA damage response, the single-stranded overhang folds back on itself and forms a telomeric loop (T-loop) or adopts a tertiary structure, referred to as a G-quadruplex. In the current study, we have examined the effects of a G-quadruplex binding and stabilizing agent, BRACO-19, on HHV-6A chromosomal integration. By stabilizing G-quadruplex structures, BRACO-19 affects the ability of the telomerase complex to elongate telomeres. Our results indicate that BRACO-19 reduces the number of clones harboring integrated HHV-6A. This study is the first of its kind and suggests that telomerase activity is essential to restore a functional telomere of adequate length following HHV-6A integration.

Changes of telomere status with aging: An update

Accumulated data have shown that most human somatic cells or tissues show irreversible telomere shortening with age, and that there are strong associations between telomere attrition and aging-related diseases, including cancers, diabetes and cognitive disorders. Although it has been largely accepted that telomere attrition is one of the major causes of aging-related disorders, critical aspects of telomere biology remain unresolved, especially the lack of standardized methodology for quantification of telomere length. Another frustrating issue is that no potentially promising methods for safe prevention of telomere erosion, or for telomere elongation, have been devised. Here, we review several methods for quantification of telomere length currently utilized worldwide, considering their advantages and drawbacks. We also summarize the results of our recent studies of human cells and tissues, mainly using quantitative fluorescence in situ hybridization and Southern blotting, including those derived from patients with progeria-prone Werner syndrome and trisomy 21, and several strains of induced pluripotent stem cells. We discuss the possible merits of using telomere shortness as an indicator, or a new marker, for diagnosis of precancerous states and aging-related disorders. In addition, we describe newly found factors that are thought to impact telomere dynamics, providing a new avenue for examining the unsolved issues related to telomere restoration and maintenance.

ATLAS: An advanced PCR-method for routine visualization of telomere length in Saccharomyces cerevisiae

Measuring telomere length is essential in telomere biology. Southern blot hybridization is the predominant method for measuring telomere length in the genetic model Saccharomyces cerevisiae. We have further developed and refined a telomere PCR approach, which was rarely used previously (mainly in specific telomeric projects), into a robust method allowing direct visualisation of telomere length differences in routine experiments with S. cerevisiae, and showing a strong correlation of results with data obtained by Southern blot hybridization. In this expanded method denoted as ATLAS (A-dvanced T-elomere L-ength A-nalysis in S. cerevisiae), we have introduced: 1) set of new primers annealing with high specificity to telomeric regions on five different chromosomes; 2) new approach for designing reverse telomere primers that is based on the ligation of an adaptor of a fixed size to telomeric ends. ATLAS can be used at the scale of individual assays and high-throughput approaches. This simple, time/cost-effective and reproducible methodology will complement Southern blot hybridization and facilitate further progress in telomere research.

Assessment of Telomere Length in Archived Formalin-Fixed, Paraffinized Human Tissue Is Confounded by Chronological Age and Storage Duration

Telomeres shorten with physiological aging but undergo substantial restoration during cancer immortalization. Increasingly, cancer studies utilize the archive of formalin-fixed, paraffin-embedded (FFPE) tissues in diagnostic pathology departments. Conceptually, such studies would be confounded by physiological telomere attrition and loss of DNA integrity from prolonged tissue storage. Our study aimed to investigate these two confounding factors. 145 FFPE tissues of surgically-resected, non-diseased appendixes were retrieved from our pathology archive, from years 2008 to 2014. Cases from 2013 to 2014 were categorized by patient chronological age (0–20 years, 21–40 years, 41–60 years, > 60 years). Telomere lengths of age categories were depicted by telomere/chromosome 2 centromere intensity ratio (TCR) revealed by quantitative fluorescence in situ hybridization. Material from individuals aged 0–20 years from years 2013/2014, 2011/2012, 2009/2010, and 2008 were compared for storage effect. Telomere integrity was assessed by telomere fluorescence intensity (TFI). Epithelial TCRs (mean ± SD) for the respective age groups were 4.84 ± 2.08, 3.64 ± 1.21, 2.03 ± 0.37, and 1.93 ± 0.45, whereas corresponding stromal TCRs were 5.16 ± 2.55, 3.84 ± 1.36, 2.49 ± 1.20, and 2.93 ± 1.24. A trend of inverse correlation with age in both epithelial and stromal tissues is supported by r = -0.69, p < 0.001 and r = -0.42, p < 0.001 respectively. Epithelial TFIs (mean ± SD) of years 2013/2014, 2011/2012, 2009/2010 and 2008 were 852.60 ± 432.46, 353.04 ± 127.12, 209.24 ± 55.57 and 429.22 ± 188.75 respectively. Generally, TFIs reduced with storage duration (r = -0.42, p < 0.001). Our findings agree that age-related telomere attrition occurs in normal somatic tissues, and suggest that an age-based reference can be established for telomere studies on FFPE tissues. We also showed that FFPE tissues archived beyond 2 years are suboptimal for telomere analysis.

Telomere attrition in beta and alpha cells with age

We have reported telomere attrition in β and α cells of the pancreas in elderly patients with type 2 diabetes, but it has not been explored how the telomere lengths of these islet cells change according to age in normal subjects. To examine the telomere lengths of β and α cells in individuals without diabetes across a wide range of ages, we conducted measurement of the telomere lengths of human pancreatic β and α cells obtained from 104 autopsied subjects without diabetes ranging in age from 0 to 100 years. As an index of telomere lengths, the normalized telomere-centromere ratio (NTCR) was determined for β (NTCRβ) and α (NTCRα) cells by quantitative fluorescence in situ hybridization (Q-FISH). We found NTCRβ and NTCRα showed almost the same levels and both decreased according to age (p < 0.001 for both). NTCRs decreased more rapidly with age and were more widely distributed (p = 0.036 for NTCRβ, p < 0.001 for NTCRα) in subjects under 18 years of age than in subjects over 18 years. There was a positive correlation between NTCRβ and NTCRα only among adult subjects (p < 0.001). In conclusion, the telomeres of β and α cells become shortened with normal aging process.

Telomere shortening leads to earlier age of onset in ALS mice

Telomere shortening has been linked to a variety of neurodegenerative diseases. Recent evidence suggests that reduced telomerase expression results in shorter telomeres in leukocytes from sporadic patients with amyotrophic lateral sclerosis (ALS) compared with healthy controls. Here, we have characterized telomere length in microglia, astroglia and neurons in human post mortem brain tissue from ALS patients and healthy controls. Moreover, we studied the consequences of telomerase deletion in a genetic mouse model for ALS. We found a trend towards longer telomeres in microglia in the brains of ALS patients compared to non-neurologic controls. Knockout of telomerase leading to telomere shortening accelerated the ALS phenotype inSOD1G93A-transgenic mice. Our results suggest that telomerase dysfunction might contribute to the age-related risk for ALS.

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.

Molecular mechanism of endothelial and vascular aging: implications for cardiovascular disease

Western societies are aging due to an increasing life span, decreased birth rates, and improving social and health conditions. On the other hand, the prevalence of cardiovascular (CV) and cerebrovascular (CBV) diseases rises with age. Thus, in view of the ongoing aging pandemic, it is appropriate to better understand the molecular pathways of aging as well as age-associated CV and CBV diseases. Oxidative stress contributes to aging of organs and the whole body by an accumulation of reactive oxygen species promoting oxidative damage. Indeed, increased oxidative stress produced in the mitochondria and cytosol of heart and brain is a common denominator to almost all CV and CBV diseases. The mitochondrial adaptor protein p66(Shc) and the family of deacetylase enzymes, the sirtuins, regulate the aging process, determine lifespan of many species and are involved in CV diseases. GDF11, a member of TGFβ superfamily with homology to myostatin also retards the aging process via yet unknown mechanisms. Recent evidence points towards a promising role of this novel 'rejuvenation' factor in reducing age-related heart disease. Finally, telomere length is also involved in aging and the development of age-related CV dysfunction. This review focuses on the latest scientific advances in understanding age-related changes of the CV and CBV system, as well as delineating potential novel therapeutic targets derived from aging research for CV and CBV diseases.

Genomic integrity and the ageing brain

DNA damage is correlated with and may drive the ageing process. Neurons in the brain are postmitotic and are excluded from many forms of DNA repair; therefore, neurons are vulnerable to various neurodegenerative diseases. The challenges facing the field are to understand how and when neuronal DNA damage accumulates, how this loss of genomic integrity might serve as a 'time keeper' of nerve cell ageing and why this process manifests itself as different diseases in different individuals.

Chromosomal instability--mechanisms and consequences

Chromosomal instability is defined as a state of numerical and/or structural chromosomal anomalies in cells. Numerous studies have documented the incidence of chromosomal instability, which acutely or chronically may lead to accelerated ageing (tissue-wide or even organismal), cancer or other genetic disorders. Potential mechanisms leading to the generation of chromosome-genome instability include erroneous/inefficient DNA repair, chromosome segregation defects, spindle assembly defects, DNA replication stress, telomere shortening/dysfunction - to name a few. Understanding the cellular and molecular mechanisms for chromosomal instability in various human cells and tissues will be useful in elucidating the cause for many age associated diseases including cancer. This approach holds a great promise for the cytogenetic assays not only for prognosis but also for diagnostic purposes in clinical settings. In this review, a multi-dimensional approach has been attempted to portray the complexity behind the incidence of chromosome-genome instability including evolutionary implications at the species level for some of the mechanisms of chromosomal instability.