Telomere length and cardiovascular disease

Unveiling Wide Spectrum Therapeutic Implications and Signaling Mechanisms of Valsartan in Diverse Disorders: A Comprehensive Review

Valsartan is an orally active non-peptide angiotensin receptor antagonist, an effective and well-tolerated anti-hypertensive drug. Besides its antihypertensive action, it has clinical implications in many other disorders, like heart failure (HF), arrhythmia, chronic kidney disease (CKD), diabetic complications (DM), atherosclerosis, etc. Besides angiotensin receptor blocking activity, valsartan reduces circulating levels of biochemical markers, such as hs-CRP, which is responsible for its anti-inflammatory and anti-oxidant activity. Moreover, valsartan also acts by inhibiting or inducing various signalling pathways, such as inducing autophagy via the AKT/mTOR/S6K pathway or inhibiting the TLR/NF-kB pathway. The current review exhaustively discusses the therapeutic implications of valsartan with specific emphasis on the mechanism of action in various disorders. The article provides a detailed spectrum of the therapeutic profile of valsartan and will likely be very useful to researchers working in the relevant research areas.

Arsenic-Induced Cardiovascular Diseases and their Correlation with Mitochondrial DNA Copy Number, Deletion, and Telomere Length in Bangladeshi Population

Arsenic contamination is a global health concern, primarily through contaminated groundwater and its entry into the food chain. The association between arsenic exposure and cardiovascular diseases (CVDs) is particularly alarming due to CVDs being the leading cause of death worldwide. Arsenic exposure has also been linked to changes in telomere length, mitochondrial DNA copy number (mtDNAcn), and deletion, further increasing the risk of CVDs. We aimed to determine whether arsenic exposure alters telomere length and mtDNAcn and deletion in a total of 50 CVD patients who underwent open heart surgery hailed from known arsenic-affected and unaffected areas in Bangladesh. Amount of arsenic was determined from the collected nails and cardiac tissues. Relative telomere length and mtDNAcn and deletion were quantified by qRT-PCR. The patients from arsenic-contaminated areas had higher average arsenic deposits in their fingers and toenails (P < 0.05) and higher cardiac tissue injury scores (P < 0.05). Moreover, approximately 1.5-fold shorter telomere length (P < 0.05, r =  - 0.775), 1.2-fold decreased mtDNAcn (P < 0.05, r = - 0.797), and an 81-fold higher amount of mitochondrial DNA deletion (P < 0.05, r = 0.784) were observed in the patients who had higher arsenic deposition in their nails. Higher levels of arsenic exposure were found to be linked to shorter telomere length, decreased mtDNAcn, and increased mitochondrial DNA deletion in the patients from As-affected areas. It can also be anticipated that the correlation of arsenic exposure with telomere length, mtDNAcn, and deletion can be used as biomarkers for early diagnosis of arsenic-induced cardiovascular diseases.

Growth differentiation factor 11: A proangiogenic drug as a potential antiaging regulating molecule

Organs and tissues are subjected to numerous alterations during aging, as a result of complex biochemical changes. Aging is certainly associated with the accumulation of "antiaging" and "proaging" factors in the systemic circulation. The effects of young blood on rejuvenation of regenerative capacity suggest the existence of multiple "proyouthful" factors, such as growth differentiation factor 11 (GDF11), in the young blood of animals. GDF11 is a member of the transforming growth factor beta (TGFβ) superfamily of cytokines, and appears to be a critical rejuvenation factor in aging organs. In the context of aging, GDF11 promotes vascular and neural plasticity of the central nervous system. Parabiosis, the surgical linking of circulations between old and young mice, was employed to identify GDF11 as an antihypertrophic factor that appears to rejuvenate the aging murine heart. Current theories suggest that GDF11 in young blood has beneficial effects on cognitive and cardiovascular functions and wound healing. The cellular mechanisms of GDF11 in cardiovascular, neurological, skin and skeletal muscle diseases are not clearly defined, but evidence indicates that it may function as a proneurogenic and proangiogenic drug. GDF11 binds and activates specific receptor complexes, which transmit signals by two procedures: the TGFβ-Smad pathway and the bone morphogenic protein (BMP)-Smad pathway. GDF11 is perhaps only the first in a series of circulating molecules that will be found to influence the aging of different tissues, and it may be a potential candidate for therapeutic intervention against angiogenesis-related disorders.

Posttransplant Complications and Genetic Loci Involved in Telomere Maintenance in Heart Transplant Patients

Reaching critically short telomeres induces cellular senescence and ultimately cell death. Cellular senescence contributes to the loss of tissue function. We aimed to determine the association between variants within genes involved in telomere length maintenance, posttransplant events, and aortic telomere length in heart transplant patients. DNA was isolated from paired aortic samples of 383 heart recipients (age 50.7 ± 11.9 years) and corresponding donors (age 38.7 ± 12.0 years). Variants within the TERC (rs12696304), TERF2IP (rs3784929 and rs8053257), and OBCF1 (rs4387287) genes were genotyped, and telomere length was measured using qPCR. We identified similar frequencies of genotypes in heart donors and recipients. Antibody-mediated rejection (AMR) was more common (p < 0.05) in carriers of at least one G allele within the TERF2IP locus (rs3784929). Chronic graft dysfunction (CGD) was associated with the TERC (rs12696304) GG donor genotype (p = 0.05). The genetic risk score did not determine posttransplant complication risk prediction. No associations between the analyzed polymorphisms and telomere length were detected in either donor or recipient DNA. In conclusion, possible associations between donor TERF2IP (rs3784929) and AMR and between TERC (rs12696304) and CGD were found. SNPs within the examined genes were not associated with telomere length in transplanted patients.

Aging of Vascular System Is a Complex Process: The Cornerstone Mechanisms

Aging is one of the most intriguing processes of human ontogenesis. It is associated with the development of a wide variety of diseases affecting all organs and their systems. The victory over aging is the most desired goal of scientists; however, it is hardly achievable in the foreseeable future due to the complexity and ambiguity of the process itself. All body systems age, lose their performance, and structural disorders accumulate. The cardiovascular system is no exception. And it is cardiovascular diseases that occupy a leading position as a cause of death, especially among the elderly. The aging of the cardiovascular system is well described from a mechanical point of view. Moreover, it is known that at the cellular level, a huge number of mechanisms are involved in this process, from mitochondrial dysfunction to inflammation. It is on these mechanisms, as well as the potential for taking control of the aging of the cardiovascular system, that we focused on in this review.

[The importance of telomeres in human herpesvirus-6A/B infections]

Herpesviruses are undisputed masters of disguise. The ability to become invisible to the immune system effectors is a complex process resting on a variety of stealth approaches. Among these, human herpesviruses-6A and -6B (HHV-6A/B) have developed the unique ability to integrate their genome within the ends of chromosomes allowing viral persistence in the absence of viral protein expression. This aptitude, unique to HHV-6A/B among human herpesviruses, requires close interactions between the telomeric regions of chromosomes and the viral genome. In this review article, the biology of telomeres and the mechanisms responsible for viral integration are discussed. In closing, the possible biological consequences of HHV-6A/B integration into chromosomal DNA are discussed.

Possible Association of Telomere Length With Sleep Duration. A Preliminary Pilot Study in a Sicilian Cohort with Centenarians

Telomere length (TL) is considered a biomarker of ageing although this topic is still debated. Also, sleep pattern changes are physiological part of the normal ageing process. In fact, it is widely recognized that sleep duration declines with age, leading to dysregulation of circadian rhythms. The aim of our study was to analyse the possible association of sleep duration with TL in a sample of 135 subjects with ages ranging from 20 to 111 years, recruited from Palermo and neighbouring municipalities in Sicily (Italy). Preliminary data suggest that relative TL (RTL) decreases with age in both men and women. However, at older ages, the difference between men and women tends to narrow. Nonagenarian and centenarian women do not show RTL values significantly different from those observed in adult and old women (40-89 years aged). Moreover, to analyse the relationship between TL and sleep, we stratified sleep duration into greater or lesser than 8-h periods. We found that centenarians, who daily sleep 8 hours or more, have longer RTL than centenarians who sleep fewer than 8 hours. Although the relatively small sample size of centenarians, we provide preliminary evidence that sleep duration may affect the RTL of centenarians. To the best of our knowledge, this is the first study to examine the relationship between centenarians, RTL and sleep duration. Further studies with greater sample size of centenarians are required to replicate and extend these data.

Telomere length and mortality risk among adults in the United States: The role of age and race and ethnicity

PURPOSE

To examine whether there was an association of leucocyte telomere length (LTL) with all-cause, cardiovascular (CVD)- and cancer-specific mortality risks among U.S. adults; and whether these associations vary with race and ethnicity and age.

METHODS

We conducted a retrospective cohort using data from the National Health and Nutrition Examination Survey, 1999 to 2002 and the 2015 Linked Mortality File on adults 25 years or older (n = 6,526 and 1,753 deaths). Cox proportional hazards regression was used to quantify the association of LTL with each outcome adjusting for baseline sociodemographic and health-related characteristics. We tested a three-way interaction for LTL, race andethnicity, and age groups.

RESULTS

After adjustment, the rate of dying for all-cause and CVD-specific mortality was at least 24% lower for a 1 kilobase increase in LTL. When compared with adults with the shortest telomere, the rates of dying were at least 17% lower for all-cause and CVD-specific mortality for those with longer telomere. For all-cause mortality, increase LTL was associated with lower rate of dying among non-Hispanic Blacks 45 years or older, and non-Hispanic Whites 65 years or older.

CONCLUSIONS

We found that increase telomere length was associated with lower all-cause and CVD-specific mortality rates among U.S. adults. For all-cause mortality, this association varies within racial andethnic groups across age groups.

Association of Homocysteine, Methionine, and MTHFR 677C>T Polymorphism With Rate of Cardiovascular Multimorbidity Development in Older Adults in Sweden

IMPORTANCE

Strong evidence links high total serum homocysteine (tHcy) and low methionine (Met) levels with higher risk of ischemic disease, but other cardiovascular (CV) diseases may also be associated with their pleiotropic effects.

OBJECTIVES

To investigate the association of serum concentrations of tHcy and Met with the rate of CV multimorbidity development in older adults and to explore the role of methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism in this association.

DESIGN, SETTING, AND PARTICIPANTS

The Swedish National Study on Aging and Care in Kungsholmen is a cohort study of randomly selected individuals aged 60 years or older. The present study included data on 1969 individuals with complete information and without CV diseases at baseline, collected from the baseline examination (2001-2004) to the fourth follow-up (2013-2016). Data analysis was conducted from January to May 2019.

EXPOSURES

Concentrations of tHcy and Met were measured from nonfasting venous blood samples. The Met:tHcy ratio was considered a possible indicator of methylation activity. MTHFR status was dichotomized as any T carriers vs noncarriers.

MAIN OUTCOME AND MEASURES

The number of CV diseases at each wave was ascertained based on medical interviews and records, laboratory test results, and drug data. Linear mixed models were used to study the association of baseline tHcy and Met levels and the rate of CV multimorbidity development, adjusting for sociodemographic characteristics, CV risk factors, chronic disease burden, and drug use.

RESULTS

Of 1969 participants, most were women (1261 [64.0%]), with a mean (SD) age of 70.9 (9.8) years; 1703 participants (86.6%) had at least a high school level of education. Baseline measurements of serum tHcy, Met, and the Met:tHcy ratio were associated with the rate of CV disease accumulation (tHcy: β = 0.023 per year; 95% CI, 0.015 to 0.030; P < .001; Met: β = -0.007 per year; 95% CI, -0.013 to -0.001; P = .02; Met:tHcy ratio: β = -0.017 per year; 95% CI, -0.023 to -0.011; P < .001). The association between low Met concentrations and the rate of CV multimorbidity development was restricted to the group with CT/TT alleles of MTHFR (β = 0.023 per year; 95% CI, 0.006 to 0.041; P = .009). Results remained largely significant when individual CV diseases were removed from the total count 1 at a time (eg, ischemic heart disease, tHcy: β = 0.023 per year; 95% CI, 0.013 to 0.027; P < .001; Met: β = -0.006 per year; 95% CI, -0.011 to -0.0003; P = .04; Met:tHcy ratio: β = -0.015 per year; 95% CI, -0.020 to -0.009; P < .001).

CONCLUSIONS AND RELEVANCE

In this study, high tHcy and low Met levels were associated with faster CV multimorbidity development in older age. The interactive association of Met concentrations and MTHFR polymorphism, together with the association found for the Met:tHcy ratio, point toward the relevance of impaired methylation in the pathogenesis of CV aging.

Effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors on ageing: Molecular mechanisms

Human ageing is determined by degenerative alterations and processes with different manifestations such as gradual organ dysfunction, tissue function loss, increased population of aged (senescent) cells, incapability of maintaining homeostasis and reduced repair capacity, which collectively lead to an increased risk of diseases and death. The inhibitors of HMG-CoA reductase (statins) are the most widely used lipid-lowering agents, which can reduce cardiovascular morbidity and mortality. Accumulating evidence has documented several pleiotropic effects of statins in addition to their lipid-lowering properties. Recently, several studies have highlighted that statins may have the potential to delay the ageing process and inhibit the onset of senescence. In this review, we focused on the anti-ageing mechanisms of statin drugs and their effects on cardiovascular and non-cardiovascular diseases.

Hypercholesterolemia Accelerates the Aging Phenotypes of Hematopoietic Stem Cells by a Tet1-Dependent Pathway

Hypercholesterolemia accelerates the phenotypes of aging in hematopoietic stem cells (HSCs). As yet, little is known about the underlying mechanism. We found that hypercholesterolemia downregulates Ten eleven translocation 1 (Tet1) in HSCs. The total HSC population was increased, while the long-term (LT) population, side population and reconstitution capacity of HSCs were significantly decreased in Tet1^−/− mice. Expression of the Tet1 catalytic domain in HSCs effectively restored the LT population and reconstitution capacity of HSCs isolated from Tet1^−/− mice. While Tet1 deficiency upregulated the expression of p19 and p21 in HSCs by decreasing the H3K27me3 modification, the restoration of Tet1 activity reduced the expression of p19, p21 and p27 by restoring the H3K27me3 and H3K36me3 modifications on these genes. These results indicate that Tet1 plays a critical role in maintaining the quiescence and reconstitution capacity of HSCs and that hypercholesterolemia accelerates HSC aging phenotypes by decreasing Tet1 expression in HSCs.

Telomeres in neurological disorders

Ever since their discovery, the telomeres and the telomerase have been topics of intensive research, first as a mechanism of cellular aging and later as an indicator of health and diseases in humans. By protecting the chromosome ends, the telomeres play a vital role in preserving the information in our genome. Telomeres shorten with age and the rate of telomere erosion provides insight into the proliferation history of cells. The pace of telomere attrition is known to increase at the onset of several pathological conditions. Telomere shortening has been emerging as a potential contributor in the pathogenesis of several neurological disorders including autism spectrum disorders (ASD), schizophrenia, Alzheimer's disease (AD), Parkinson's disease (PD) and depression. The rate of telomere attrition in the brain is slower than that of other tissues owing to the low rate of cell proliferation in brain. Telomere maintenance is crucial for the functioning of stem cells in brain. Taking together the studies on telomere attrition in various neurological disorders, an association between telomere shortening and disease status has been demonstrated in schizophrenia, AD and depression, in spite of a few negative reports. But, studies in ASD and PD have failed to produce conclusive results. The cause-effect relationship between TL and neurological disorders is yet to be elucidated. The factors responsible for telomere erosion, which have also been implicated in the pathogenesis of neurological disorders, need to be explored in detail. Telomerase activation is now being considered as a potential therapeutic strategy for neurological disorders.

Curcumin Inhibits Age-Related Vascular Changes in Aged Mice Fed a High-Fat Diet

Inhibiting the onset of arteriosclerotic disease, which has been increasing due to the westernized diet and aging, is a significant social challenge. Curcumin, a type of polyphenol, has anti-oxidative effects and anti-inflammatory action and is expected to treat and to have prophylactic effects on different diseases. In this study, we examined the effects of long-term administration of curcumin on vascular aging and chronic inflammation—the causes of arteriosclerotic disease. Eight-week-old C57BL/6J mice were fed with high fat diet (HFD) or 0.1% curcumin-mixed HFD (HFD + Cu) until 80 weeks old (n = 20 for each group). After the breeding, we examined the expression of antioxidant enzymes, heme oxygenase-1 (HO-1), oxidative stress, vascular aging, and inflammatory changes in the aorta. In the HFD group, oxidative stress increased with decreased sirt1 expression in the aorta followed by increased senescent cells and enhanced inflammation. Whereas in the HFD + Cu group, HO-1 was induced in the aorta with the suppression of oxidative stress. Additionally, it was shown that sirt1 expression in the aorta in the HFD + Cu group remained at a level comparable to that of the 8-week-old mice with suppression of increased senescent cells and enhanced inflammation. Consequently, disorders associated with HFD were resolved. These results suggest that curcumin might be a food with a prophylactic function against arteriosclerotic disease.

Telomere Biology and Thoracic Aortic Aneurysm

Ascending aortic aneurysms are mostly asymptomatic and present a great risk of aortic dissection or perforation. Consequently, ascending aortic aneurysms are a source of lethality with increased age. Biological aging results in progressive attrition of telomeres, which are the repetitive DNA sequences at the end of chromosomes. These telomeres play an important role in protection of genomic DNA from end-to-end fusions. Telomere maintenance and telomere attrition-associated senescence of endothelial and smooth muscle cells have been indicated to be part of the pathogenesis of degenerative vascular diseases. This systematic review provides an overview of telomeres, telomere-associated proteins and telomerase to the formation and progression of aneurysms of the thoracic ascending aorta. A better understanding of telomere regulation in the vascular pathology might provide new therapeutic approaches. Measurements of telomere length and telomerase activity could be potential prognostic biomarkers for increased risk of death in elderly patients suffering from an aortic aneurysm.

Association Between Oxidative Stress and Peripheral Leukocyte Telomere Length in Patients with Premature Coronary Artery Disease

Background

Leukocyte telomere length (LTL) is regarded as a potential marker of biological aging. Oxidative stress plays a major role in the rate of telomeric DNA loss. The aim of this study was to explore whether the LTL was shorter in Chinese patients with premature coronary artery disease (PCAD) than in non-CAD controls and to determine the relationship between oxidative stress and LTL shortening in this population.

Material/Methods

Patients for coronary angiography were recruited. In total, 128 patients with PCAD and 128 non-CAD controls were enrolled. Samples of circulating leukocytes and plasma were collected. The mean LTL was measured using a polymerase chain reaction-based assay and expressed as the ratio of telomere repeat copies to single-copy gene (SCG) copies (T/S ratio). Reactive oxygen species (ROS) levels and total antioxidant capacity (T-AOC) were determined in plasma.

Results

Both the T/S ratio (0.88±0.86 vs. 1.10±0.57, P=0.015) and telomere base pairs (4.97±1.37 kb vs. 5.32±0.91 kb, P=0.015) were significantly shorter in the PCAD group than in non-CAD controls. The T-AOC levels of the PCAD group were significantly lower than those of the non-CAD controls (0.482 mM [0.279, 0.603 mM]) vs. 0.778 mM [0.421, 0.924 mM], P=0.000). The ratio of T-AOC to ROS in the PCAD patients was significantly decreased compared to that of the non-CAD controls (0.1026±0. 1587 [Mm*ml/ng] vs. 0.1435±0.1946 [Mm*ml/ng], P=0.013).

Conclusion

The results point to a potential link between reduced LTLs in patients with PCAD and early onset of atherosclerosis. The decline in antioxidant capacity may play an important role in accelerating the attrition of telomeres in PCAD patients.

Is telomere length a biomarker of neurological disorders?

Telomeres are DNA-protein complexes that form protective caps at the termini of chromosomes, maintaining genomic stability. In this review, we provide a comprehensive overview on the usefulness of telomere length (TL) as biomarkers of neurological disorders. The implications of TL in relation to cognitive ability, cognitive aging and cognitive decline in neurodegenerative disorders are also briefly discussed. Our review suggests that at present it is difficult to draw a reliable conclusion regarding the contribution of TL to neurological disorders. Further, it needs to be examined whether leukocyte TL, which is generally considered as a surrogate marker of TL in other tissues, serves as an indicator of central nervous system TL.

HHV-6A/B Integration and the Pathogenesis Associated with the Reactivation of Chromosomally Integrated HHV-6A/B

Unlike other human herpesviruses, human herpesvirus 6A and 6B (HHV-6A/B) infection can lead to integration of the viral genome in human chromosomes. When integration occurs in germinal cells, the integrated HHV-6A/B genome can be transmitted to 50% of descendants. Such individuals, carrying one copy of the HHV-6A/B genome in every cell, are referred to as having inherited chromosomally-integrated HHV-6A/B (iciHHV-6) and represent approximately 1% of the world's population. Interestingly, HHV-6A/B integrate their genomes in a specific region of the chromosomes known as telomeres. Telomeres are located at chromosomes' ends and play essential roles in chromosomal stability and the long-term proliferative potential of cells. Considering that the integrated HHV-6A/B genome is mostly intact without any gross rearrangements or deletions, integration is likely used for viral maintenance into host cells. Knowing the roles played by telomeres in cellular homeostasis, viral integration in such structure is not likely to be without consequences. At present, the mechanisms and factors involved in HHV-6A/B integration remain poorly defined. In this review, we detail the potential biological and medical impacts of HHV-6A/B integration as well as the possible chromosomal integration and viral excision processes.

Accelerated telomere shortening: Tracking the lasting impact of early institutional care at the cellular level

Studies examining the association between early adversity and longitudinal changes in telomere length within the same individual are rare, yet are likely to provide novel insight into the subsequent lasting effects of negative early experiences. We sought to examine the association between institutional care history and telomere shortening longitudinally across middle childhood and into adolescence. Buccal DNA was collected 2-4 times, between the ages of 6 and 15 years, in 79 children enrolled in the Bucharest Early Intervention Project (BEIP), a longitudinal study exploring the impact of early institutional rearing on child health and development. Children with a history of early institutional care (n=50) demonstrated significantly greater telomere shortening across middle childhood and adolescence compared to never institutionalized children (n=29). Among children with a history of institutional care, randomization to high quality foster care was not associated with differential telomere attrition across development. Cross-sectional analysis of children randomized to the care as usual group indicated shorter telomere length was associated with greater percent of the child's life spent in institutional care up to age 8. These results suggest that early adverse care from severe psychosocial deprivation may be embedded at the molecular genetic level through accelerated telomere shortening.

Association between telomere length and diabetes mellitus: A meta-analysis

Objective We investigated the relationship between diabetes and telomere length by meta-analysis. Methods We searched five popular databases for articles published between 1990 and 2015 using "diabetes" and "telomere" as search terms. Data were processed with RevMan5, and random- or fixed-effects meta-analysis was applied. The effects of geographical region, diabetes type, body mass index (BMI), age and sex were examined. Funnel plots were applied to evaluate publication bias. Results Seventeen articles were obtained from 571 references. We identified a significant association between telomere length and diabetes mellitus (standardized mean difference [SMD]: -3.41; 95% confidence interval [CI]: -4.01, -2.80; heterogeneity, I2 = 99%) by comparing 5575 patients with diabetes and 6349 healthy individuals. The pooled SMD by geographic region indicated a significant association between shortened telomere length and diabetes mellitus (SMD: -3.41; 95% CI: -4.01, -2.80; heterogeneity, I2 = 99%). In addition, telomere length was significantly associated with age (SMD: -3.41; 95% CI: -4.01, -2.80), diabetes type (SMD: -3.41; 95% CI: -4.01, -2.80), BMI (SMD: -1.61; 95% CI: -1.98, -1.23) and sex (SMD: -4.94; 95% CI: -9.47, -0.40). Conclusions The study demonstrated a close relationship between diabetes mellitus and telomere length, which was influenced by region, age, diabetes type, BMI and sex.

Macrophages in age-related chronic inflammatory diseases

Chronic inflammation is the common pathological basis for such age-associated diseases as cardiovascular disease, diabetes, cancer and Alzheimer’s disease. A multitude of bodily changes occur with aging that contribute to the initiation and development of inflammation. In particular, the immune system of elderly individuals often exhibits diminished efficiency and fidelity, termed immunosenescence. But, although immune responses to new pathogens and vaccines are impaired, immunosenescence is also characterized by a basal systemic inflammatory state. This alteration in immune system function likely promotes chronic inflammation. Changes in the tissue microenvironment, such as the accumulation of cell debris, and systemic changes in metabolic and hormonal signals, also likely contribute to the development of chronic inflammation. Monocyte/macrophage lineage cells are crucial to these age-associated changes, which culminate in the development of chronic inflammatory diseases. In this review, we will summarize the diverse physiological and pathological roles of macrophages in the chronic inflammation underlying age-associated diseases.

Leukocyte telomere length positively correlates with duration of lithium treatment in bipolar disorder patients

Bipolar disorder (BD) has been suggested to be associated with accelerated aging and premature cell senescence. While findings on shorter telomeres in BD are controversial, a recent study showed that long-term lithium treatment correlates with longer telomeres in BD. In our study, we sought to investigate the correlation between leukocyte telomere length (LTL) and long-term lithium treatment in a sample of 200 BD patients characterized for lithium response. We also compared data from two different methods commonly used to measure telomere length, quantitative PCR (qPCR) and quantitative fluorescence in situ hybridization (Q-FISH). We also measured, for the first time, the effect of lithium in vitro on the expression of the telomerase gene in human-derived neural progenitor cells (NPCs). Our findings showed that LTL correlated negatively with age (p=0.0002) and was independent of sex, diagnosis, age at onset, suicidal behavior, number of mood episodes, response to lithium and use of other psychotropic medications. After correcting for age, LTL was positively correlated with lithium treatment duration in patients treated for more than two years (n=150, R=0.17, p=0.037). There was a significant correlation between data measured with qPCR and Q-FISH (p=0.012, R=0.826). Lithium treatment increased telomerase expression in NPCs, though this effect was not statistically significant. Our data support previous findings showing that long-term lithium treatment associates with longer telomeres in BD, though this effect appeared to be independent from clinical response to the treatment. Moreover, we suggested for the first time that lithium increases the expression of telomerase gene in human neural progenitor cells.

Role of NOX2 in mediating doxorubicin-induced senescence in human endothelial progenitor cells

Senescence exerts a great impact on both biological and functional properties of circulating endothelial progenitor cells (EPCs), especially in cardiovascular diseases where the physiological process of aging is accelerated upon clinical administration of certain drugs such as doxorubicin. EPC impairment contributes to doxorubicin-induced cardiotoxicity. Doxorubicin accelerates EPC aging, although mechanisms underlying this phenomenon remain to be fully clarified. Here we investigated if Nox2 activity is able to modulate the premature senescence induced in vitro by doxorubicin in human EPCs. Results showed that in conditioned media obtained from late EPC cultures, the levels of interleukin-6, isoprostanes and nitric oxide bioavailability were increased and reduced respectively after 3h of doxorubicin treatment. These derangements returned to physiological levels when cells were co-treated with apocynin or gp91ds-tat (antioxidant and specific Nox2 inhibitors, respectively). Accordingly, Nox2 activity resulted to be activated by doxorubicin. Importantly, we found that Nox2 inhibition reduced doxorubicin-induced EPC senescence, as indicated by a lower percentage of β-gal positive EPCs. In conclusion, Nox2 activity efficiently contributes to the mechanism of oxidative stress-induced increase in premature aging conferred by doxorubicin. The importance of modulation of Nox2 in human EPCs could reveal a useful tool to restore EPC physiological function and properties.

Comparison of the relative telomere length measured in leukocytes and eleven different human tissues

The relative length of telomeres measured in peripheral blood leukocytes is a commonly used system marker for biological aging and can also be used as a biomarker of cardiovascular aging. However, to what extent the telomere length in peripheral leukocytes reflects telomere length in different organ tissues is still unclear. Therefore, we have measured relative telomere length (rTL) in twelve different human tissues (peripheral blood leukocytes, liver, kidney, heart, spleen, brain, skin, triceps, tongue mucosa, intercostal skeletal muscle, subcutaneous fat, and abdominal fat) from twelve cadavers (age range of 29 week of gestation to 88 years old). The highest rTL variability was observed in peripheral leukocytes, and the lowest variability was found in brain. We found a significant linear correlation between leukocyte rTL and both intercostal muscle (R=0.68, P<0.02) and liver rTL (R=0.60, P<0.05) only. High rTL variability was observed between different organs from one individual. Furthermore, we have shown that even slight DNA degradation (modeled by sonication of genomic DNA) leads to false rTL shortening. We conclude that the rTL in peripheral leukocytes is not strongly correlated with the rTL in different organs.

Low-Dose Fluvastatin and Valsartan Rejuvenate the Arterial Wall Through Telomerase Activity Increase in Middle-Aged Men

BACKGROUND AND AIM

Previously, we have shown that slightly to moderately aged arteries in middle-aged males can be rejuvenated functionally by sub-therapeutic, low-dose fluvastatin and valsartan treatment. Here, we explore whether this treatment could also increase telomerase activity. We hypothesized that telomerase activity might be associated with (1) an improvement of arterial wall properties and (2) a reduction of inflammatory/oxidative stress parameters (both observed in our previous studies).

METHODS

The stored blood samples from 130 apparently healthy middle-aged males treated with fluvastatin (10 mg daily), valsartan (20 mg daily), fluvastatin and valsartan combination (10 and 20 mg), respectively, and placebo (control), were analyzed. The samples were taken before and after treatment lasting 30 days, and 5 months after treatment discontinuation. Telomerase activity was measured in blood leukocytes by a TaqMan Gene Expression Assay.

RESULTS

Low-dose fluvastatin or valsartan increased telomerase activity (106.9% and 59.5% respectively; both p < 0.05, vs. control), whereas their combination was even more effective (an increase of 228.0%; p < 0.001, vs. control). No change was noted in the control group. Importantly, increased telomerase activity obtained in the combination group significantly correlated with arterial function, measured by flow-mediated dilation (FMD) (r = 0.79; p < 0.001) and C-reactive protein concentration (r = -0.54; p = 0.02) and total anti-oxidative status (r = 0.50; p = 0.03).

CONCLUSION

We found that a low-dose combination of fluvastatin and valsartan substantially increased telomerase activity, which significantly correlated with an improvement of endothelial function and a decrease of inflammation/oxidative stress. These findings could lead to a new innovative approach to arterial rejuvenation.

Sleep as a potential fundamental contributor to disparities in cardiovascular health

Optimal sleep is integral to health but is commonly not obtained. Despite its wide-ranging public health impact, sleep health is considered only rarely by policy makers, employers, schools, and others whose policies and structures can adversely affect sleep. An inadequate duration of sleep and poor-quality sleep are prevalent in minority and low-income populations, and may be fundamental to racial and socioeconomic status inequities that contribute to a range of health conditions, including cardiovascular disease (CVD). This review examines the relationship between sleep and disparities in CVD. We describe the public health importance of sleep and the role of sleep duration, as well as the two most common disorders (sleep apnea and insomnia) as risk factors for a number of chronic diseases. We use a multilevel model focused on population health and health disparities, which is based on the notion that individual behaviors, such as sleep, are influenced by complex and dynamic interrelations among individuals and their physical and social environments. We also describe modifiable factors that contribute to insufficient sleep and circadian misalignment, propose potential interventions in various sectors (e.g., neighborhoods, schools, workplaces) that can address social structures that contribute to disparities, and recommend areas for future research. Integrating sleep into public health research will identify novel approaches for closing gaps in health disparities.

Implicit Cognition: Implications for Global Health Disparities

Implicit cognition, or our unconscious thoughts and beliefs, is an important predictor of our behaviors and decisions. It also predicts outcomes related to physical and mental health at the level of the individual and influences the dynamics of the patient-physician relationship. This article outlines specific ways in which implicit measures of cognition predict vulnerabilities to adverse health and contribute to social disparities in health and discusses important future directions for this body of research.

Inherited chromosomally integrated human herpesvirus 6 as a predisposing risk factor for the development of angina pectoris

Inherited chromosomally integrated human herpesvirus-6 (iciHHV-6) results in the germ-line transmission of the HHV-6 genome. Every somatic cell of iciHHV-6+ individuals contains the HHV-6 genome integrated in the telomere of chromosomes. Whether having iciHHV-6 predisposes humans to diseases remains undefined. DNA from 19,597 participants between 40 and 69 years of age were analyzed by quantitative PCR (qPCR) for the presence of iciHHV-6. Telomere lengths were determined by qPCR. Medical records, hematological, biochemical, and anthropometric measurements and telomere lengths were compared between iciHHV-6+ and iciHHV-6- subjects. The prevalence of iciHHV-6 was 0.58%. Two-way ANOVA with a Holm-Bonferroni correction was used to determine the effects of iciHHV6, sex, and their interaction on continuous outcomes. Two-way logistic regression with a Holm-Bonferroni correction was used to determine the effects of iciHHV6, sex, and their interaction on disease prevalence. Of 50 diseases monitored, a single one, angina pectoris, is significantly elevated (3.3×) in iciHHV-6+ individuals relative to iciHHV-6- subjects (P = 0.017; 95% CI, 1.73-6.35). When adjusted for potential confounding factors (age, body mass index, percent body fat, and systolic blood pressure), the prevalence of angina remained three times greater in iciHHV-6+ subjects (P = 0.015; 95%CI, 1.23-7.15). Analyses of telomere lengths between iciHHV-6- without angina, iciHHV-6- with angina, and iciHHV-6+ with angina indicate that iciHHV-6+ with angina have shorter telomeres than age-matched iciHHV-6- subjects (P = 0.006). Our study represents, to our knowledge, the first large-scale analysis of disease association with iciHHV-6. Our results are consistent with iciHHV-6 representing a risk factor for the development of angina.

The relationship between telomere length and beekeeping among Malaysians

The belief that beekeepers live longer than anyone else is present since ages. However, no research has been done to explore the longevity of life in beekeepers. Here, we investigated the telomere length in 30 male beekeepers and 30 male non-beekeepers and associated them with the longevity of life using Southern analysis of terminal restriction fragments (TRFs) generated by Hinf I/Rsa I digestion of human genomic DNA using TeloTAGGG Telomere Length Assay. Interestingly, we found that the telomere length of male beekeepers was significantly longer than those of male non-beekeepers with a p value of less than 0.05, suggesting that beekeepers may have longer life compared to non-beekeepers. We further found that the consumption of bee products for a long period and frequent consumption of bee products per day are associated with telomere length. An increase of year in consuming bee products is associated with a mean increase in telomere length of 0.258 kbp. In addition, an increase in frequency of eating bee products per day was also associated with a mean increase of 2.66 kbp in telomere length. These results suggested that bee products might play some roles in telomere length maintenance.

Homocysteine accelerates senescence of endothelial cells via DNA hypomethylation of human telomerase reverse transcriptase

OBJECTIVE

Homocysteine can accelerate the senescence of endothelial progenitor cells or endothelial cells (ECs) via telomerase inactivation and length shortening. However, the underlying mechanism is unclear. Here, we investigated whether homocysteine promotes endothelial senescence by reducing the expression and activity of human telomerase reverse transcriptase (hTERT) by DNA methylation to reduce ECs telomerase activity.

APPROACH AND RESULTS

When compared with primary human umbilical vein endothelial cells grown under standard conditions, ECs with chronic homocysteine treatment showed accelerated upregulation of p16, p21, and p53, markers of cellular senescence, during 6 to 10 passages. Interestingly, homocysteine-stimulated but not angiotensin II-stimulated ECs senescence could be reversed by hypermethylation induced by folic acid or s-adenosylmethionine supplementation. Meanwhile, homocysteine promoted the shortening of telomere length specifically related to restoration of hTERT transcriptional expression and CCCTC-binding factor binding sites with hTERT promoter hypomethylation, as detected by quantitative real-time polymerase chain reaction, Western blot, methylation-specific polymerase chain reaction, and bisulfite sequencing assay. Electrophoretic mobility shift assay and chromatin immunoprecipitation results showed that homocysteine-reduced telomere activity and homocysteine-induced EC senescence might contribute to hTERT promoter demethylation by increasing CCCTC-binding factor repression and interfering in the SP1 binding to the demethylated hTERT promoter, which might relate with reduced of DNA methyltransferase 1. Furthermore, the CCCTC-binding factor-dependent mechanism of homocysteine-reduced hTERT expression via DNA demethylation was confirmed in aortic endothelia of mice with hyperhomocysteine levels.

CONCLUSIONS

CCCTC-binding factor and SP1 cross talk may contribute to homocysteine-reduced hTERT DNA methylation and expression in endothelial senescence.

Weight loss associated with bariatric surgery does not restore short telomere length of severe obese patients after 1 year

BACKGROUND

Telomere shortening is physiologically associated with ageing but it may be influenced by oxidative stress and chronic inflammation, linked to obesity. Thus, obesity might represent an additional cause of telomere attrition. We aim to study relative telomere length (RTL) in obese subjects with and without metabolic syndrome and to assess the effect of weight loss induced by bariatric surgery.

METHODS

We evaluated RTL in 107 obese subjects (62 with metabolic syndrome and 45 without metabolic syndrome), compared to 130 age-matched non-obese subjects. We also measured RTL in a subgroup of 93 obese patients prior to and 3, 6, 9 and 12 months after surgery.

RESULTS

RTL of obese subjects was significantly shorter (p<0.0001) than non-obese subjects but without differences between patients with and without metabolic syndrome (p=0.19). RTL was significantly shorter than baseline at 3, 6, 9 and 12 months after bariatric surgery.

CONCLUSIONS

These results confirm that obese subjects have shorter telomeres compared to non-obese subjects, but RTL is not influenced by the presence of metabolic syndrome. RTL shows an additional attrition during the immediate post-operative period, probably due to a catabolic state.

A cautionary tale for autologous vascular tissue engineering: impact of human demographics on the ability of adipose-derived mesenchymal stem cells to recruit and differentiate into smooth muscle cells

Autologous tissue-engineered blood vessels (TEBVs) generated using adult stem cells have shown promising results, but many preclinical evaluations do not test the efficacy of stem cells from patient populations likely to need therapy (i.e., elderly and diabetic humans). Two critical functions of these cells will be (i) secreting factors that induce the migration of host cells into the graft and (ii) differentiating into functional vascular cells themselves. The purpose of this study was to analyze whether adipose-derived mesenchymal stem cells (AD-MSCs) sourced from diabetic and elderly patients have a reduced ability to promote human smooth muscle cell (SMC) migration and differentiation potential toward SMCs, two important processes in stem cell-based tissue engineering of vascular grafts. SMC monolayers were disrupted in vitro by a scratch wound and were induced to close the wound by exposure to media conditioned by AD-MSCs from healthy, elderly, and diabetic patients. Media conditioned by AD-MSCs from healthy patients promoted the migration of SMCs and did so in a dose-dependent manner; heating the media to 56°C eliminated the media's potency. AD-MSCs from diabetic and elderly patients had a decreased ability to differentiate into SMCs under angiotensin II stimulation; however, only AD-MSCs from elderly donors were unable to promote SMC migration. Gender and body-mass index of the patients showed no effect on either critical function of AD-MSCs. In conclusion, AD-MSCs from elderly patients may not be suitable for autologous TEBVs due to inadequate promotion of SMC migration and differentiation.

Are the leukocyte telomere length attrition and telomerase activity alteration potential predictor biomarkers for sporadic TAA in aged individuals?

A large variability in occurrence, complications, and age/gender manifestations characterizes individual susceptibility of sporadic thoracic aortic aneurysms (TAA), even in subjects with the same risk factor profiles. The reasons are poorly understood. On the other hand, TAA pathophysiology mechanisms remain unclear than those involved in abdominal aorta aneurysms. However, recent evidence is suggesting a crucial role of biological ageing in inter-individual risk variation of cardiovascular diseases, including sporadic TAA. Biological age rather than chronological age is a better predictor of vascular risk. Relevant assumptions support this concept. In confirming this evidence and our preliminary data, the mean of blood leukocyte telomere length, through use of terminal restriction fragment assay and in blood samples from sporadic TAA patients and controls, was examined. Telomerase activity was also analyzed in two groups. In addition, we verified the weight of genetic inflammatory variants and the major TAA risk factors in telomere/telomerase impairment. Aorta histopathological abnormalities and systemic inflammatory mediators were ultimately correlated with telomere/telomerase impairment. Data obtained demonstrated shorter telomeres and a reduced telomerase activity in TAA patients significantly associated with a genetic inflammatory risk profile, age, gender, smoking, hypertension, a histopathological phenotype, and higher levels of systemic inflammatory mediators than controls. In conclusion, telomere and telomerase activity's detection might be used as predictor biomarkers of sporadic TAA. Their impairment also suggests a strong role of vascular ageing in sporadic TAA, evocated by both environmental and genetic inflammatory factors.

Influence of endothelial dysfunction on telomere length in subjects with metabolic syndrome: LIPGENE study

Previous evidences support that increased oxidative stress (OxS) may play an important role in metabolic syndrome (MetS) and both are closely linked to vascular dysfunction. This study determined whether there is a relationship between endothelial function and relative telomere length (RTL) in MetS subjects. In this cross-sectional study from the LIPGENE cohort, a total of 88 subjects (36 men and 52 women) were divided into four groups by quartiles of telomere length. We measured ischemic reactive hyperemia (IRH), total nitrite (NO) and protein carbonyl (PC) plasma levels, F2-isoprostanes urinary levels, and superoxide dismutase (SOD) and glutathione peroxidase (GPx) plasma activities. IRH and NO plasma levels were higher in subjects with longer RTL (quartiles 3 and 4), while PC plasma levels, F2-isoprostanes urinary levels, and GPx and SOD plasma activities were lower in quartile 4 subjects (longest RTL). Additionally, MetS subjects with longer RTL had greater homeostatic model assessment-β level and lower triglycerides plasma levels. Our results suggest that endothelial dysfunction, associated with high levels of OxS, could be entailed in an increment of telomere attrition. Thus, further support of the molecular and cellular mechanisms involved in vascular dysfunction may contribute to the development of strategies to decelerate vascular aging or prevent cardiovascular disease.

QTL mapping of leukocyte telomere length in American Indians: the Strong Heart Family Study

Telomeres play a central role in cellular senescence and are associated with a variety of age-related disorders such as dementia, Alzheimer's disease and atherosclerosis. Telomere length varies greatly among individuals of the same age, and is heritable. Here we performed a genome-wide linkage scan to identify quantitative trait loci (QTL) influencing leukocyte telomere length (LTL) measured by quantitative PCR in 3,665 American Indians (aged 14-93 years) from 94 large, multi-generational families. All participants were recruited by the Strong Heart Family Study (SHFS), a prospective study to identify genetic factors for cardiovascular disease and its risk factors in American Indians residing in Oklahoma, Arizona and Dakota. LTL heritability was estimated to be between 51% and 62%, suggesting a strong genetic predisposition to interindividual variation of LTL in this population. Significant QTLs were localized to chromosome 13 (Logarithm of odds score (LOD)=3.9) at 13q12.11, to 18q22.2 (LOD=3.2) and to 3p14.1 (LOD=3.0) for Oklahoma. This is the first study to identify susceptibility loci influencing leukocyte telomere variation in American Indians, a minority group suffering from a disproportionately high rate of type 2 diabetes and other age-related disorders.

Discrimination, racial bias, and telomere length in African-American men

BACKGROUND

Leukocyte telomere length (LTL) is an indicator of general systemic aging, with shorter LTL being associated with several chronic diseases of aging and earlier mortality. Identifying factors related to LTL among African Americans may yield insights into mechanisms underlying racial disparities in health.

PURPOSE

To test whether the combination of more frequent reports of racial discrimination and holding a greater implicit anti-black racial bias is associated with shorter LTL among African-American men.

METHODS

Cross-sectional study of a community sample of 92 African-American men aged between 30 and 50 years. Participants were recruited from February to May 2010. Ordinary least squares regressions were used to examine LTL in kilobase pairs in relation to racial discrimination and implicit racial bias. Data analysis was completed in July 2013.

RESULTS

After controlling for chronologic age and socioeconomic and health-related characteristics, the interaction between racial discrimination and implicit racial bias was significantly associated with LTL (b=-0.10, SE=0.04, p=0.02). Those demonstrating a stronger implicit anti-black bias and reporting higher levels of racial discrimination had the shortest LTL. Household income-to-poverty threshold ratio was also associated with LTL (b=0.05, SE=0.02, p<0.01).

CONCLUSIONS

Results suggest that multiple levels of racism, including interpersonal experiences of racial discrimination and the internalization of negative racial bias, operate jointly to accelerate biological aging among African-American men. Societal efforts to address racial discrimination in concert with efforts to promote positive in-group racial attitudes may protect against premature biological aging in this population.

Hypercholesterolemia induces oxidant stress that accelerates the ageing of hematopoietic stem cells

Background

Clinical studies suggest that hypercholesterolemia may cause ageing in hematopoietic stem cells (HSCs) because ageing‐associated alterations were found in peripheral blood cells and their bone marrow residing precursors in patients with advanced atherosclerosis. We hypothesized that hypercholesterolemia induces oxidant stress in hematopoietic stems cells that accelerates their ageing.

Methods and Results

Here we show that HSCs from ApoE^−/− mice, as well as HSCs from C57Bl/6 mice fed a high cholesterol diet (HCD) accumulated oxLDL and had greater ROS levels. In accordance, the expression pattern of the genes involved in ROS metabolism changed significantly in HSCs from ApoE^−/− mice. Hypercholesterolemia caused a significant reduction in phenotypically defined long‐term HSC compartment, telomere length, and repopulation capacity of KTLS cells, indicating accelerated ageing in these cells. Gene array analysis suggested abnormal cell cycle status, and the key cell cycle regulators including p19^ARF, p27^Kip1 and p21^Waf1 were upregulated in KTLS cells from hypercholesterolemic mice. These effects were p38‐dependent and reversed in vivo by treatment of hypercholesterolemic mice with antioxidant N‐acetylcysteine. The oxidant stress also caused aberrant expression of Notch1 that caused loss of quiescence and proliferation leading to the expansion of KTLS compartment in hypercholesterolemic mice.

Conclusion

Taken together, we provide evidence that hypercholesterolemia can cause oxidant stress that accelerates the ageing and impairs the reconstitution capacity of HSCs.

Lack of causal relationship between leukocyte telomere length and coronary heart disease

OBJECTIVE

To investigate the association between genetic variation in telomerase RNA component (TERC) and leukocyte telomere length (LTL) with risk of coronary heart disease (CHD).

METHODS AND RESULTS

An analysis of LTL was conducted, focusing on two SNPs in 2 community-based cohort populations comprising 3500 Chinese Han individuals. In addition, LTL ratio was determined in a case-control setting involving 4351 participants: 2211 healthy individuals and 2140 CHD patients. The association between LTL and the presence and extent of cardiovascular and cerebrovascular lesions were tested. Results confirmed the association of rs12696304 and rs16847897 with LTL in the Chinese Han population (P=1.63×10(-6) and P=1.44×10(-7), respectively). However, these SNPs confer a moderate risk for CHD but did not achieve significant threshold after multiple corrections. Decreased LTL ratio was associated with CHD (odds ratio [OR], 1.13; 95% confidence interval [CI], 1.02-1.34; P<0.01). In addition, the LTL ratio in CHD patients was related to numbers of vascular disease lesions.

CONCLUSIONS

Our results do not support a causal role of LTL for the development of CHD. However, LTL may be related to complex conditions associated with cardiovascular and cerebrovascular disease manifestations.

Telomeres and cardiovascular disease risk: an update 2013

Leukocyte telomere length (LTL) has been regarded as a potential marker of biologic aging because it usually shortens in a predictable way with age. Recently, a growing interest in cardiovascular aging has led to a number of new epidemiologic studies investigating LTL in various disease conditions. Some methodological problems exist because there are different methods available to determine LTL, and standardization is much needed. For example, in the majority of studies, patients with early-onset coronary heart disease have been shown to have shorter LTL. In addition, patients with diabetes mellitus complications tend to have shorter LTL than control subjects. On the other hand, increased left ventricular hypertrophy or mass is associated with longer LTL, and studies investigating hypertension have reported both shorter and longer LTL than found in normotensive control subjects. There is, therefore, a need for longitudinal studies to elucidate these complicated relationships further, to provide estimations of telomere attrition rates, and to overcome analytical problems when only cross-sectional studies are used. The understanding of cardiovascular aging and telomere biology may open up new avenues for interventions, such as stem cell therapy or agents that could retard this aging process over and beyond conventional risk factor control.

Longer telomere length in patients with schizophrenia

Previous studies have reported an association between shorter leukocyte telomere length and schizophrenia (SCZ). The aim of the present study was to replicate this finding in a large sample of SCZ patients (n=539) and population-based controls (n=519). In addition, the possible influence of SCZ severity on telomere length - as measured by age of onset, mode of onset, and course of the disorder - was investigated. Telomere length was negatively associated with age in both patients and controls. This is a consistently reported phenomenon, related to the problem of DNA end-replication. However, in contrast to previous findings, SCZ patients displayed longer telomeres compared to controls (p=0.015). No association was found with any SCZ-severity subphenotype. Interestingly, recent studies have reported associations between longer leukocyte telomere length and both smaller hippocampal volume, and poorer episodic memory performance. Both phenotypes are common in patients with SCZ. Further studies are warranted to investigate whether the present association between SCZ and increased telomere length was driven by such associations, or rather by association with the clinical disease per se or other associated phenotypes, endophenotypes or lifestyle factors.

MiR-146a as marker of senescence-associated pro-inflammatory status in cells involved in vascular remodelling

In order to identify new markers of vascular cell senescence with potential in vivo implications, primary cultured endothelial cells, including human umbilical vein endothelial cells (HUVECs), human aortic endothelial cells (HAECs), human coronary artery endothelial cells (HCAECs) and ex vivo circulating angiogenic cells (CACs), were analysed for microRNA (miR) expression. Among the 367 profiled miRs in HUVECs, miR-146a, miR-9, miR-204 and miR-367 showed the highest up-regulation in senescent cells. Their predicted target genes belong to nine common pathways, including Toll-like receptor signalling (TLR) that plays a pivotal role in inflammatory response, a key feature of senescence (inflammaging). MiR-146a was the most up-regulated miR in the validation analysis (>10-fold). Mimic and antagomir transfection confirmed TLR's IL-1 receptor-associated kinase (IRAK1) protein modulation in both young and senescent cells. Significant correlations were observed among miR-146a expression and β-galactosidase expression, telomere length and telomerase activity. MiR-146a hyper-expression was also validated in senescent HAECs (>4-fold) and HCAECs (>30-fold). We recently showed that CACs from patients with chronic heart failure (CHF) presented a distinguishing feature of senescence. Therefore, we also included miR-146a expression determination in CACs from 37 CHF patients and 35 healthy control subjects (CTR) for this study. Interestingly, a 1,000-fold increased expression of miR-146a was observed in CACs of CHF patients compared to CTR, along with decreased expression of IRAK1 protein. Moreover, significant correlations among miR-146a expression, telomere length and telomerase activity were observed. Overall, our findings indicate that miR-146a is a marker of a senescence-associated pro-inflammatory status in vascular remodelling cells.

Telomeres and atherosclerosis

Abstract

In humans and other multicellular organisms that have an extended lifespan, the leading causes of death are atherosclerotic cardiovascular disease and cancer. Experimental and clinical evidence indicates that these age-related disorders are linked through dysregulation of telomere homeostasis. Telomeres are DNA protein structures located at the terminal end of chromosomes and shorten with each cycle of cell replication, thereby reflecting the biological age of an organism. Critically shortened telomeres provoke cellular senescence and apoptosis, impairing the function and viability of a cell. The endothelial cells within atherosclerotic plaques have been shown to display features of cellular senescence. Studies have consistently demonstrated an association between shortened telomere length and coronary artery disease (CAD).

Several of the CAD risk factors and particularly type 2 diabetes are linked to telomere shortening and cellular senescence. Our interest in telomere biology was prompted by the high incidence of premature CAD and diabetes in a subset of our population, and the hypothesis that these conditions are premature-ageing syndromes. The assessment of telomere length may serve as a better predictor of cardiovascular risk and mortality than currently available risk markers, and anti-senescence therapy targeting the telomere complex is emerging as a new strategy in the treatment of atherosclerosis. We review the evidence linking telomere biology to atherosclerosis and discuss methods to preserve telomere length.

Telomere length in patients with systemic lupus erythematosus and its associations with carotid plaque

OBJECTIVE

To evaluate telomere length (TL) between patients with SLE and healthy controls and to test if TL is associated with carotid plaque.

METHODS

A pilot study of 154 patients with SLE and 152 controls was performed from the SOLVABLE (Study of Lupus Vascular and Bone Long-Term Endpoints) cohort. Demographic and cardiovascular disease (CVD) factors were collected at baseline. The presence or absence of plaque was evaluated by B-mode US. Genomic DNA was isolated from whole peripheral blood. TL was quantified using real-time quantitative PCR.

RESULTS

SLE women had a short TL compared with healthy controls (4.57 vs 5.44 kb, P = 0.03). SLE women showed shorter TL than controls across all age groups: <35 years (4.38 vs 6.37 kb), 35-44 years (4.52 vs 5.30 kb), 45-54 years (4.77 vs 5.68 kb) and ≥55 years (4.60 vs 4.71 kb). Among patients with SLE and carotid plaque there was a trend towards shorter TL at a younger age and it was significantly lower in the 35- to 44-year age group when compared with controls (P = 0.025). Multiple logistic regression analysis indicated a risk of carotid plaque with older age [odds ratio (OR) 1.09; 95% CI 1.06, 1.12] but not with TL (OR 1.05; 95% CI 0.97, 1.13).

CONCLUSION

SLE women had significantly shorter TL than controls. SLE women trended towards shorter TL at a younger age. When carotid plaque was identified, the younger SLE women had shorter TL. Only older age but not shorter TL was independently associated with carotid plaque. Additional studies are needed to confirm if TL is a novel biomarker for cardiovascular disease in SLE.

Mechanisms of telomere loss and their consequences for chromosome instability

The ends of chromosomes in mammals, called telomeres, are composed of a 6-bp repeat sequence, TTAGGG, which is added on by the enzyme telomerase. In combination with a protein complex called shelterin, these telomeric repeat sequences form a cap that protects the ends of chromosomes. Due to insufficient telomerase expression, telomeres shorten gradually with each cell division in human somatic cells, which limits the number of times they can divide. The extensive cell division involved in cancer cell progression therefore requires that cancer cells must acquire the ability to maintain telomeres, either through expression of telomerase, or through an alternative mechanism involving recombination. It is commonly thought that the source of many chromosome rearrangements in cancer cells is a result of the extensive telomere shortening that occurs prior to the expression of telomerase. However, despite the expression of telomerase, tumor cells can continue to show chromosome instability due to telomere loss. Dysfunctional telomeres in cancer cells can result from oncogene-induced replication stress, which results in double-strand breaks (DSBs) at fragile sites, including telomeres. DSBs near telomeres are especially prone to chromosome rearrangements, because telomeric regions are deficient in DSB repair. The deficiency in DSB repair near telomeres is also an important mechanism for ionizing radiation-induced replicative senescence in normal human cells. In addition, DSBs near telomeres can result in chromosome instability in mouse embryonic stem cells, suggesting that telomere loss can contribute to heritable chromosome rearrangements. Consistent with this possibility, telomeric regions in humans are highly heterogeneous, and chromosome rearrangements near telomeres are commonly involved in human genetic disease. Understanding the mechanisms of telomere loss will therefore provide important insights into both human cancer and genetic disease.

Leukocyte telomere length in HIV-infected pregnant women treated with antiretroviral drugs during pregnancy and their uninfected infants

OBJECTIVES

HIV disease can lead to accelerated telomere attrition, although certain drugs used as part of antiretroviral therapy (ART) can inhibit telomerase reverse transcriptase activity. This could in turn lead to shorter telomeres. We hypothesized that HIV and ART exposure would be associated with shorter leukocyte telomere length (TL) in exposed mother/infant pairs compared with controls.

METHODS

In these retrospective and prospective observational cohort studies, TL was evaluated in peripheral blood leukocytes obtained from HIV-infected pregnant women treated with ART and their uninfected infants, and compared with HIV untreated (retrospective cohort) or HIV mothers and their infants (prospective cohort).

RESULTS

In HIV-infected ART-exposed mothers, leukocyte TL was not significantly shorter than that in HIV untreated mothers or HIV controls, nor was their infants' TL significantly different. Cord blood of ART-exposed infants exhibited TL shorter than that from infants born to HIV-negative mothers. Placenta also showed evidence of shorter TL after adjustment for relevant covariates. Factors associated with shorter maternal and infant TL included smoking and the use of drugs of addiction in pregnancy.

CONCLUSIONS

These results suggest that maternal HIV infection or exposure to ART has minimal effect on infant leukocyte TL, a reassuring finding. In contrast, tissues that express higher telomerase activity such as umbilical cord blood and placenta appear comparatively more affected by ART. Smoking and the use of drugs of addiction have a negative impact on maternal and infant leukocyte TL, possibly through oxidative telomere damage.

Is the mean blood leukocyte telomere length a predictor for sporadic thoracic aortic aneurysm? Data from a preliminary study

Telomeres have been postulated as a universal clock that shortens in parallel with cellular aging. They are specialized DNA-protein structures at the ends of chromosome with remarkable functions--preventing their recognition as double-stranded DNA breaks, protecting their recombination and degradation, and avoiding a DNA damage cellular response. Telomere shortening is currently considered the best aging marker, but is also a predictor for age-related diseases, including cardiovascular diseases. Biological age clearly seems to be a better predictor of vascular risk rather than chronological age. This concept is supported by key assumptions that peripheral blood leukocyte telomere content accurately reflects that of the vascular wall and its decrease is associated with premature vascular disease. Thus, we are analyzing whether the mean of blood leukocyte telomere length might also be a predictor for sporadic thoracic aortic aneurysm (S-TAA). The preliminary results seem to be promising. Shorter telomeres were detected in patients than in controls. Thus, mean of blood leukocyte telomere length could contribute to identify individuals at S-TAA risk.

Telomere length in circulating serum DNA as a novel non-invasive biomarker for cirrhosis: a nested case-control analysis

BACKGROUND & AIMS

Previous studies have indicated that telomere length is associated with altered risk of various tumours including hepatitis B virus (HBV)-related hepatocellular carcinoma. However, the association between telomere length and the risk of cirrhosis has not been reported.

METHODS

In this nested case-control study, we used real-time quantitative PCR to determine the relative telomere length (RTL) in serum DNA samples from 100 HBV-related cirrhosis cases and 100 frequency-matched HBV controls, and evaluated the associations between RTL and cirrhosis risk by logistic regression analyses.

RESULTS

We found that cirrhotic cases had a significantly longer RTL (median, 0.36; range, 0.08-1.87) than non-cirrhotic controls (median, 0.20; range, 0.05-1.11) (P < 0.0001). Compared with subjects with short RTL, those with long RTL had a significantly increased cirrhosis risk [odds ratio, 2.76, 95% confidence interval, 1.50-5.10; P = 0.001]. Quartile analysis further indicated a dose-response effect for this association. Compared with patients with the lowest quartile of RTL, the cirrhosis risk for those with the second, third and highest quartile of RTL was 2.68 (0.91-7.87, P = 0.073), 3.37 (1.32-10.54, P = 0.013) and 6.64 (2.41-18.32, P < 0.0001) respectively (P(trend) <0.0001). Moreover, the area under the receiver operating characteristic curve increased from 0.60 (epidemiological variables) to 0.72 (epidemiological variables plus RTL), with statistically significant difference assessed by bootstrap analysis.

CONCLUSIONS

Our study presents the first epidemiological evidence that RTL in serum DNA could potentially be used as a simple, inexpensive and non-invasive marker of cirrhosis risk, a finding that warrants further investigations in independent retrospective and prospective populations.

Functionality, growth and accelerated aging of tissue engineered living autologous vascular grafts

Living autologous tissue engineered vascular-grafts (TEVGs) with growth-capacity may overcome the limitations of contemporary artificial-prostheses. However, the multi-step in vitro production of TEVGs requires extensive ex vivo cell-manipulations with unknown effects on functionality and quality of TEVGs due to an accelerated biological age of the cells. Here, the impact of biological cell-age and tissue-remodeling capacity of TEVGs in relation to their clinical long-term functionality are investigated. TEVGs were implanted as pulmonary-artery (PA) replacements in juvenile sheep and followed for up to 240 weeks (∼4.5years). Telomere length and telomerase activity were compared amongst TEVGs and adjacent native tissue. Telomerase-activity of in vitro expanded autologous vascular-cells prior to seeding was <5% as compared to a leukemic cell line, indicating biological-aging associated with decreasing telomere-length with each cellular-doubling. Up to 100 weeks, the cells in the TEVGs had consistently shorter telomeres compared to the native counterpart, whereas no significant differences were detectable at 240 weeks. Computed tomography (CT) analysis demonstrated physiological wall-pressures, shear-stresses, and flow-pattern comparable to the native PA. There were no signs of degeneration detectable and continuous native-analogous growth was confirmed by vessel-volumetry. TEVGs exhibit a higher biological age compared to their native counterparts. However, despite of this tissue engineering technology related accelerated biological-aging, growth-capacity and long-term functionality was not compromised. To the contrary, extensive in-vivo remodeling processes with substantial endogenous cellular turnover appears to result in "TEVG rejuvenation" and excellent clinical performance. As these large-animal results can be extrapolated to approximately 20 human years, this study suggests long-term clinical-safety of cardiovascular in vitro tissue engineering and may contribute to safety-criteria as to first-in-man clinical-trials.