The individual's signature of telomere length distribution

Mitochondrial biogenesis, telomere length and cellular senescence in Parkinson's disease and Lewy body dementia

Progressive age is the single major risk factor for neurodegenerative diseases. Cellular aging markers during Parkinson's disease (PD) have been implicated in previous studies, however the majority of studies have investigated the association of individual cellular aging hallmarks with PD but not jointly. Here, we have studied the association of PD with three aging hallmarks (telomere attrition, mitochondrial dysfunction, and cellular senescence) in blood and the brain tissue. Our results show that PD patients had 20% lower mitochondrial DNA copies but 26% longer telomeres in blood compared to controls. Moreover, telomere length in blood was positively correlated with medication (Levodopa Equivalent Daily Dose, LEDD) and disease duration. Similar results were found in brain tissue, where patients with Parkinson's disease (PD), Parkinson's disease dementia (PDD) and Dementia with Lewy Bodies (DLB) showed (46-95%) depleted mtDNA copies, but (7-9%) longer telomeres compared to controls. In addition, patients had lower mitochondrial biogenesis (PGC-1α and PGC-1β) and higher load of a cellular senescence marker in postmortem prefrontal cortex tissue, with DLB showing the highest effect among the patient groups. Our results suggest that mitochondrial dysfunction (copy number and biogenesis) in blood might be a valuable marker to assess the risk of PD. However, further studies with larger sample size are needed to evaluate these findings.

Telomere and Telomerase: Biological Markers of Organic Vital Force State and Homeopathic Treatment Effectiveness

BACKGROUND

 Philosophical-scientific correlations described in previous studies suggest that the genome can be the biological representation of the vital force, whilst the disease-promoting epigenetic alterations would be the biological representation of the chronic miasmas. In this study, we expand the functional correlation between vital force and chromosomes, describing the mechanism of action of the telomere-telomerase complex in the context of physiological balance.

AIMS

 The aim of the work is to study the role of the telomere-telomerase complex in cell vitality, biological aging, and the health-disease process, with the goal of proposing the use of telomere length as a biomarker of the vital force state and the effectiveness of homeopathic treatment.

RESULTS

 Similar to the vital force, telomere length and telomerase enzyme activity play an important role in maintaining cellular vitality, biological longevity, and physiological homeostasis. Telomere shortening functions as a biomarker of vital imbalance and is associated with numerous diseases and health disorders. On the other hand, health-promotion practices neutralize the pathological shortening of the telomeres, acting therapeutically in diseases or age-dependent health disorders.

CONCLUSIONS

 As a hypothetical biomarker of the vital force state, an intra-individual analysis of the mean leukocyte telomere length before, during, and after homeopathic treatment can be used as a biomarker of therapeutic effectiveness.

A genetic determinant of VEGF-A levels is associated with telomere attrition

Telomere length (TL) is a hallmark of cellular aging and is associated with chronic diseases development. The vascular endothelial growth factor A (VEGF-A), a potent angiogenesis factor, is implicated in the pathophysiology of many chronic diseases. The aim of the present study was to investigate the associations between VEGF-A and TL.

TL in leukocytes (LTL) and skeletal muscle (MTL) were measured, 10 VEGF-related polymorphisms genotyped, and VEGF-A plasma concentrations determined in 402 individuals from the TELARTA cohort. LTL/MTL ratio was calculated as an estimate of lifelong TL attrition. Associations between VEGF-A variants and levels, and TL parameters were investigated.

We identified one significant association between the minor allele (T) of rs6993770 variant and LTL/MTL ratio (P=0.001143, β=0.0148, SE=0.004516). The rs6993770 is an intronic variant of the ZFPM2 gene, which is involved in haematopoiesis and the identified association with increased telomere attrition could be due to increased haematopoiesis. No significant epistatic interaction was identified, and no association was found between levels of VEGF-A and any of assessed phenotypes.

We identified a potential common genetic regulation between VEGF-A and telomere length attrition that could be explained by mechanisms of increased hematopoiesis and production of platelets. VEGF-A and TL could play an important role in personalized medicine of chronic diseases and identification of molecular links between them can promote the understanding of their complex implications.

Telomeres: New players in immune-mediated inflammatory diseases?

Telomeres are repetitive DNA sequences located at the ends of linear chromosomes that preserve the integrity and stability of the genome. Telomere dysfunctions due to short telomeres or altered telomere structures can ultimately lead to replicative cellular senescence and chromosomal instability, both mechanisms being hallmarks of ageing. Chronic inflammation, oxidative stress and finally telomere length (TL) dynamics have been shown to be involved in various age-related non-communicable diseases (NCDs). Immune-mediated inflammatory diseases (IMIDs), including affections such as inflammatory bowel disease, psoriasis, rheumatoid arthritis, spondyloarthritis and uveitis belong to this group of age-related NCDs. Although in recent years, we have witnessed the emergence of studies in the literature linking these IMIDs to TL dynamics, the causality between these diseases and telomere attrition is still unclear and controversial. In this review, we provide an overview of available studies on telomere dynamics and discuss the utility of TL measurements in immune-mediated inflammatory diseases.

Telomere Attrition in Neurodegenerative Disorders

Telomere attrition is increased in various disorders and is therefore a potential biomarker for diagnosis and/or prognosis of these disorders. The contribution of telomere attrition in the pathogenesis of neurodegenerative disorders is yet to be fully elucidated. We are reviewing the current knowledge regarding the telomere biology in two common neurodegenerative disorders, Alzheimer's disease (AD), and Parkinson's disease (PD). Furthermore, we are discussing future prospective of telomere research in these disorders. The majority of studies reported consistent evidence of the accelerated telomere attrition in AD patients, possibly in association with elevated oxidative stress levels. On the other hand in PD, various studies reported contradictory evidence regarding telomere attrition. Consequently, due to the low specificity and sensitivity, the clinical benefit of telomere length as a biomarker of neurodegenerative disease development and progression is not yet recognized. Nevertheless, longitudinal studies in large carefully selected cohorts might provide further elucidation of the complex involvement of the telomeres in the pathogenesis of neurodegenerative diseases. Telomere length maintenance is a complex process characterized by environmental, genetic, and epigenetic determinants. Thus, in addition to the selection of the study cohort, also the selection of analytical methods and types of biological samples for evaluation of the telomere attrition is of utmost importance.

Walking and biologic ageing: Evidence based on NHANES telomere data

The length of telomeres is an objective measure of biologic ageing. This study evaluated the extent minutes of walking per week are associated with leukocyte telomere length (LTL) in a random sample of 5,823 U.S. adults. The investigation was cross-sectional and data were obtained from the National Health and Nutrition Examination Survey (NHANES). LTL was measured by the quantitative polymerase chain reaction method. Walking minutes was calculated from walking frequency and duration measures. Results showed that for each year of chronological age, telomeres were 15.6 base pairs shorter (P < 0.0001). With walking minutes and LTL treated as continuous variables, the relationship was quadratic, not linear (F = 11.2, P = 0.0023). With walking time divided into three categories, adults who performed ≥ 150 minutes of walking per week had longer telomeres than those who did no regular walking, and those who did some, but less than the recommendation (F = 5.0, P = 0.0137). Regular walkers were estimated to have a biologic ageing advantage associated with 6.5-7.6 years less biologic ageing compared to non-walkers, after adjusting for covariates. Additional investigations designed to study causality and the mechanisms associated with the walking and LTL relationship are needed.

Telomeres and Telomere Length: A General Overview

Telomeres are highly conserved tandem nucleotide repeats that include proximal double-stranded and distal single-stranded regions that in complex with shelterin proteins afford protection at chromosomal ends to maintain genomic integrity. Due to the inherent limitations of DNA replication and telomerase suppression in most somatic cells, telomeres undergo age-dependent incremental attrition. Short or dysfunctional telomeres are recognized as DNA double-stranded breaks, triggering cells to undergo replicative senescence. Telomere shortening, therefore, acts as a counting mechanism that drives replicative senescence by limiting the mitotic potential of cells. Telomere length, a complex hereditary trait, is associated with aging and age-related diseases. Epidemiological data, in general, support an association with varying magnitudes between constitutive telomere length and several disorders, including cancers. Telomere attrition is also influenced by oxidative damage and replicative stress caused by genetic, epigenetic, and environmental factors. Several single nucleotide polymorphisms at different loci, identified through genome-wide association studies, influence inter-individual variation in telomere length. In addition to genetic factors, environmental factors also influence telomere length during growth and development. Telomeres hold potential as biomarkers that reflect the genetic predisposition together with the impact of environmental conditions and as targets for anti-cancer therapies.

The Relation of Optimism to Relative Telomere Length in Older Men and Women

OBJECTIVE

Mounting evidence suggests that higher optimism is associated with reduced risk of age-related morbidities and premature mortality. However, possible biological mechanisms underlying these associations remain understudied. One hypothesized mechanism is a slower rate of cellular aging, which in turn delays age-related declines in health.

METHODS

We used data from two large cohort studies to test the hypothesis that higher optimism is associated with longer leukocyte telomere length. With cross-sectional data from the Health and Retirement Study (HRS; n = 6417; mean age = 70 years) and the Women's Health Initiative (WHI; N = 3582; mean age = 63 years), we used linear regression models to examine the association of optimism with relative telomere length (assessed in leukocytes from saliva [HRS] or plasma [WHI]). Models adjusted for sociodemographics, depression, health status, and health behaviors.

RESULTS

Considering both optimism and telomere length as continuous variables, we found consistently null associations in both cohorts, regardless of which covariates were included in the models. In models adjusting for demographics, depression, comorbidities, and health behaviors, optimism was not associated with mean relative telomere length (HRS: β = -0.002, 95% confidence interval = -0.014 to 0.011; WHI: β = -0.004, 95% confidence interval = -0.017 to 0.009).

CONCLUSIONS

Findings do not support mean telomere length as a mechanism that explains observed relations of optimism with reduced risk of chronic disease in older adults. Future research is needed to evaluate other potential biological markers and pathways.

Effects of Inflammation and Depression on Telomere Length in Young Adults in the United States

Little is known about the associations of inflammation and depression with telomere length. Using data from the National Health and Nutrition Examination Survey (NHANES) 1999–2002, the current study assessed the effects of inflammation and depression on telomere length in 1141 young adults in the USA. Depression status was assessed from the World Health Organization Composite International Diagnostic Interview and inflammation status was measured based on C-reactive protein (CRP) concentrations. Information on telomere length was obtained using the quantitative polymerase chain reaction method to measure telomere length relative to standard reference DNA (T/S ratio). Unadjusted and adjusted linear and logistic regression models were used to assess the relationship between the tertiles of CRP concentration and the telomere length stratified by the status of depression such as major depression or depressed affect vs. no depression. The adjusted models were controlled for age, family poverty income ratio, race/ethnicity, marital status, physical activity, body mass index, and alcohol drinking status. A significant and decreasing linear trend in telomere length was found as CRP levels increased in men, regardless of the depression status, and women with major depression or depressed affect (p values < 0.05). Among men without depression, those with an elevated CRP level had increased odds of having a shortened telomere length compared to men with low CRP levels after controlling for covariates (adjusted odds ratio 1.77, 95% confidence interval (CI) 1.09–2.90). In women, there was no association between CRP and telomere length, regardless of the depression status. In conclusion, there was a significant and inverse association between inflammation and telomere length according to the depression status in men but not in women. The present findings may be of clinical significance for the monitoring of inflammation levels and depression status as determinants of telomere length.