Relationship between average leucocyte telomere length and the presence or severity of idiopathic dilated cardiomyopathy in black Africans

Neonatal administration of fenofibrate had no developmental programming effect on the lipid profile and relative leucocyte telomere lengths of adolescent rats fed a high-fructose diet postnatally

Telomere length, a marker of ageing, is susceptible to developmental programming that may cause its accelerated attrition. Metabolic syndrome triggers telomere attrition. Fenofibrate, a peroxisome proliferator-activated receptor-alpha agonist, is protective against telomere attrition. We investigated the impact of fenofibrate administered during suckling on the lipid profile and leucocyte telomere lengths of rats fed a high-fructose diet post-weaning. Suckling Sprague-Dawley pups (n = 119) were allocated to four groups and gavaged with either 10 mL·kg-1 body mass 0.5% dimethyl sulfoxide, 100 mg·kg-1 body mass fenofibrate, fructose (20%, w / v), or a combination of fenofibrate and fructose for 15 days. Upon weaning, each of the initial groups was split into two subgroups: one had plain water while the other had fructose solution (20%, w / v) to drink for 6 weeks. Blood was collected for DNA extraction and relative leucocyte telomere length determination by real-time PCR. Plasma triglycerides and cholesterol were also quantified. The treatments had no effect (p > 0.05) on body mass, cholesterol concentration, and relative leucocyte telomere lengths in both sexes. Post-weaning fructose increased triglyceride concentrations (p < 0.05) in female rats. Fenofibrate administered during suckling did not affect ageing nor did it prevent high fructose-induced hypertriglyceridaemia in female rats.

Association of telomere length with diabetes mellitus and idiopathic dilated cardiomyopathy in a South Indian population: A pilot study

Telomere shortening has been associated with ageing and with many age-related diseases including cancer, coronary artery disease, heart failure and diabetes. We sought to investigate the link between telomere shortening and age-related diseases like type 2 diabetes mellitus (DM) (without any complications: DM; with neuropathic complication: DN) and idiopathic dilated cardiomyopathy (IDCM) in south Indian population. We compared telomere lengths of blood lymphocytes taken from patients with associated age-related diseases, namely DM (n = 47), DN (n = 52) and IDCM (n = 34) and controls (n = 46). In addition, we evaluated the relationship between echocardiographic left ventricular ejection fraction (LVEF), left ventricular end diastolic and systolic diameters (LVEDd and LVESd) and telomere length in IDCM patients. Telomere length negatively correlated with age in the cohorts with diabetes and IDCM, and in controls. Average telomere length in diabetes and IDCM patients was significantly shorter than that of controls either before or after adjustments for age and sex. Duration of diabetes in patients with type 2 diabetes did not correlate with telomere length. No correlation was found between the length of telomeres and echocardiography parameters like LVEF, LVEDd and LVESd in IDCM patients. Though echocardiographic characteristics of IDCM did not correlate with telomere length, telomere shortening was found to be accelerated in diabetes (both DM and DN) and IDCM in a south Indian population. Neuropathic complication in diabetes had no effect on telomere shortening. While telomere shortening is a cause or a consequence of diabetic and cardiac pathology remains further investigation, the current study substantiates the usefulness of telomere length measurements as a marker in conjunction with other biochemical markers of age-related diseases.

Longitudinal analysis of somatic and germ-cell telomere dynamics in outbred mice

Although telomere length (TL) shortens with age in most tissues, an age-related increase in length has been described in sperm through a mechanism that is not yet fully understood. Changes in TL with age in the same individual have not been explored. This longitudinal study examines TL dynamics in somatic tissue and gametes during an entire lifespan in an outbred mouse population (from 8 to up to 114 weeks of age). Our findings indicate a reduced life expectancy in males compared to females (84.75 ± 9.23 vs. 113.16 ± 0.20 weeks) and significant variability in TL dynamics between individuals. While with aging, a clear reduction in TL was produced in somatic cells and oocytes, telomeres in sperm cells significantly lengthened. Finally, we found evidence indicating that telomere elongation in sperm during aging may be dependent on different mechanisms, such as the survival of spermatogonia with longer telomeres and the alternative lengthening of telomeres mechanism in meiotic and postmeiotic spermatogenic cells.

Bovine telomere dynamics and the association between telomere length and productive lifespan

Average telomere length (TL) in blood cells has been shown to decline with age in a range of vertebrate species, and there is evidence that TL is a heritable trait associated with late-life health and mortality in humans. In non-human mammals, few studies to date have examined lifelong telomere dynamics and no study has estimated the heritability of TL, despite these being important steps towards assessing the potential of TL as a biomarker of productive lifespan and health in livestock species. Here we measured relative leukocyte TL (RLTL) in 1,328 samples from 308 Holstein Friesian dairy cows and in 284 samples from 38 female calves. We found that RLTL declines after birth but remains relatively stable in adult life. We also calculated the first heritability estimates of RLTL in a livestock species which were 0.38 (SE = 0.03) and 0.32 (SE = 0.08) for the cow and the calf dataset, respectively. RLTL measured at the ages of one and five years were positively correlated with productive lifespan (p < 0.05). We conclude that bovine RLTL is a heritable trait, and its association with productive lifespan may be used in breeding programmes aiming to enhance cow longevity.

Longitudinal changes in telomere length and associated genetic parameters in dairy cattle analysed using random regression models

Telomeres cap the ends of linear chromosomes and shorten with age in many organisms. In humans short telomeres have been linked to morbidity and mortality. With the accumulation of longitudinal datasets the focus shifts from investigating telomere length (TL) to exploring TL change within individuals over time. Some studies indicate that the speed of telomere attrition is predictive of future disease. The objectives of the present study were to 1) characterize the change in bovine relative leukocyte TL (RLTL) across the lifetime in Holstein Friesian dairy cattle, 2) estimate genetic parameters of RLTL over time and 3) investigate the association of differences in individual RLTL profiles with productive lifespan. RLTL measurements were analysed using Legendre polynomials in a random regression model to describe TL profiles and genetic variance over age. The analyses were based on 1,328 repeated RLTL measurements of 308 female Holstein Friesian dairy cattle. A quadratic Legendre polynomial was fitted to the fixed effect of age in months and to the random effect of the animal identity. Changes in RLTL, heritability and within-trait genetic correlation along the age trajectory were calculated and illustrated. At a population level, the relationship between RLTL and age was described by a positive quadratic function. Individuals varied significantly regarding the direction and amount of RLTL change over life. The heritability of RLTL ranged from 0.36 to 0.47 (SE = 0.05-0.08) and remained statistically unchanged over time. The genetic correlation of RLTL at birth with measurements later in life decreased with the time interval between samplings from near unity to 0.69, indicating that TL later in life might be regulated by different genes than TL early in life. Even though animals differed in their RLTL profiles significantly, those differences were not correlated with productive lifespan (p = 0.954).

Cardiomyocyte-Specific Telomere Shortening is a Distinct Signature of Heart Failure in Humans

Background

Telomere defects are thought to play a role in cardiomyopathies, but the specific cell type affected by the disease in human hearts is not yet identified. The aim of this study was to systematically evaluate the cell type specificity of telomere shortening in patients with heart failure in relation to their cardiac disease, age, and sex.

Methods and Results

We studied cardiac tissues from patients with heart failure by utilizing telomere quantitative fluorescence in situ hybridization, a highly sensitive method with single‐cell resolution. In this study, total of 63 human left ventricular samples, including 37 diseased and 26 nonfailing donor hearts, were stained for telomeres in combination with cardiomyocyte‐ or α‐smooth muscle cell‐specific markers, cardiac troponin T, and smooth muscle actin, respectively, and assessed for telomere length. Patients with heart failure demonstrate shorter cardiomyocyte telomeres compared with nonfailing donors, which is specific only to cardiomyocytes within diseased human hearts and is associated with cardiomyocyte DNA damage. Our data further reveal that hypertrophic hearts with reduced ejection fraction exhibit the shortest telomeres. In contrast to other reported cell types, no difference in cardiomyocyte telomere length is evident with age. However, under the disease state, telomere attrition manifests in both young and older patients with cardiac hypertrophy. Finally, we demonstrate that cardiomyocyte‐telomere length is better sustained in women than men under diseased conditions.

Conclusions

This study provides the first evidence of cardiomyocyte‐specific telomere shortening in heart failure.

Evaluation of telomere length in human cardiac tissues using cardiac quantitative FISH

Telomere length has been correlated with various diseases, including cardiovascular disease and cancer. The use of currently available telomere-length measurement techniques is often restricted by the requirement of a large amount of cells (Southern-based techniques) or the lack of information on individual cells or telomeres (PCR-based methods). Although several methods have been used to measure telomere length in tissues as a whole, the assessment of cell-type-specific telomere length provides valuable information on individual cell types. The development of fluorescence in situ hybridization (FISH) technologies enables the quantification of telomeres in individual chromosomes, but the use of these methods is dependent on the availability of isolated cells, which prevents their use with fixed archival samples. Here we describe an optimized quantitative FISH (Q-FISH) protocol for measuring telomere length that bypasses the previous limitations by avoiding contributions from undesired cell types. We have used this protocol on small paraffin-embedded cardiac-tissue samples. This protocol describes step-by-step procedures for tissue preparation, permeabilization, cardiac-tissue pretreatment and hybridization with a Cy3-labeled telomeric repeat complementing (CCCTAA)₃ peptide nucleic acid (PNA) probe coupled with cardiac-specific antibody staining. We also describe how to quantify telomere length by means of the fluorescence intensity and area of each telomere within individual nuclei. This protocol provides comparative cell-type-specific telomere-length measurements in relatively small human cardiac samples and offers an attractive technique to test hypotheses implicating telomere length in various cardiac pathologies. The current protocol (from tissue collection to image procurement) takes ∼28 h along with three overnight incubations. We anticipate that the protocol could be easily adapted for use on different tissue types.

Bedside-to-Bench Translational Research for Chronic Heart Failure: Creating an Agenda for Clients Who Do Not Meet Trial Enrollment Criteria

Congestive heart failure (CHF) is a chronic condition usually without cure. Significant developments, particularly those addressing pathophysiology, mainly started at the bench. This approach has seen many clinical observations initially explored at the bench, subsequently being trialed at the bedside, and eventually translated into clinical practice. This evidence, however, has several limitations, importantly the generalizability or external validity. We now acknowledge that clinical management of CHF is more complicated than merely translating bench-to-bedside evidence in a linear fashion. This review aims to help explore this evolving area from an Australian perspective. We describe the continuation of research once core evidence is established and describe how clinician-scientist collaboration with a bedside-to-bench view can help enhance evidence translation and generalizability. We describe why an extension of the available evidence or generating new evidence is occasionally needed to address the increasingly diverse cohort of patients. Finally, we explore some of the tools used by basic scientists and clinicians to develop evidence and describe the ones we feel may be most beneficial.

Impact of gender and menopausal status on relationships between biological aging, as indexed by telomere length, and aortic stiffness

BACKGROUND

Telomere length predicts cardiovascular disease (CVD) possibly through an impact of telomere attrition on aortic stiffness. Whether reduced biological aging and a lack of telomere length-aortic stiffness relationships in women contribute to the lower prevalence of CVD in women, prior to menopause, is uncertain.

METHODS

We evaluated the relationship between telomere length and carotid-femoral (aortic) pulse wave velocity (PWV) in 580 randomly recruited participants of Black African descent (age = 44 ± 19 years; women: n = 361; premenopausal: n = 195). PWV was determined using carotid and femoral applanation tonometry (SphygmoCor). Relative leukocyte telomere length (T/S) was measured using quantitative real-time polymerase chain reaction assays.

RESULTS

Men and women had similar T/S. T/S was inversely correlated with age (r = -0.14, P < 0.001) and this association was similar in all (r = -0.14, P < 0.01) and premenopausal (r = -0.17, P < 0.05) women as in men (r = -0.14, P < 0.05). An inverse relationship between T/S and PWV was noted both before (r = -0.20, P < 0.0001) and after (partial r = -0.14, P < 0.001) adjustments for confounders. No interaction between T/S and either sex or menopausal status was independently associated with PWV, and T/S was independently correlated with PWV in all (partial r = -0.14, P < 0.01) and premenopausal (partial r = -0.18, P < 0.05) women and in men (partial r = -0.15, P < 0.05).

CONCLUSIONS

Gender and premenopausal status do not affect age-related decreases in T/S and associations between T/S and PWV. In participants of African descent in whom telomere length did not differ by gender, the impact of gender prior to menopause on CVD is unlikely to be attributed to differences in the effect of biological aging on aortic stiffness.

Leukocyte telomere length and left ventricular function after acute ST-elevation myocardial infarction: data from the glycometabolic intervention as adjunct to primary coronary intervention in ST elevation myocardial infarction (GIPS-III) trial

Background

Telomere length has been associated with coronary artery disease and heart failure. We studied whether leukocyte telomere length is associated with left ventricular ejection fraction (LVEF) after ST-elevation myocardial infarction (STEMI).

Methods and results

Leukocyte telomere length (LTL) was determined using the monochrome multiplex quantitative PCR method in 353 patients participating in the glycometabolic intervention as adjunct to primary percutaneous coronary intervention in STEMI III trial. LVEF was assessed by magnetic resonance imaging. The mean age of patients was 58.9 ± 11.6 years, 75 % were male. In age- and gender-adjusted models, LTL at baseline was significantly associated with age (beta ± standard error; −0.33 ± 0.01; P < 0.01), gender (0.15 ± 0.03; P < 0.01), TIMI flow pre-PCI (0.05 ± 0.03; P < 0.01), TIMI flow post-PCI (0.03 ± 0.04; P < 0.01), myocardial blush grade (−0.05 ± 0.07; P < 0.01), serum glucose levels (−0.11 ± 0.01; P = 0.03), and total leukocyte count (−0.11 ± 0.01; P = 0.04). At 4 months after STEMI, LVEF was well preserved (54.1 ± 8.4 %) and was not associated with baseline LTL (P = 0.95). Baseline LTL was associated with n-terminal pro-brain natriuretic peptide (NT-proBNP) at 4 months (−0.14 ± 0.01; P = 0.02), albeit not independent for age and gender.

Conclusion

Our study does not support a role for LTL as a causal factor related to left ventricular ejection fraction after STEMI.