Healthy aging and disease: role for telomere biology?

The association between intelligence and telomere length: a longitudinal population based study

Low intelligence has been associated with poor health and mortality, but underlying mechanisms remain obscure. We hypothesized that low intelligence is associated with accelerated biological ageing as reflected by telomere length; we suggested potential mediation of this association by unhealthy behaviors and low socioeconomic position. The study was performed in a longitudinal population-based cohort study of 895 participants (46.8% males). Intelligence was measured with the Generalized Aptitude-Test Battery at mean age 52.8 years (33–79 years, SD = 11.3). Leukocyte telomere length was measured by PCR. Lifestyle and socioeconomic factors were assessed using written self-report measures. Linear regression analyses, adjusted for age, sex, and telomere length measured at the first assessment wave (T1), showed that low intelligence was associated with shorter leukocyte telomere length at approximately 2 years follow-up (beta = .081, t = 2.160, p = .031). Nearly 40% of this association was explained by an unhealthy lifestyle, while low socioeconomic position did not add any significant mediation. Low intelligence may be a risk factor for accelerated biological ageing, thereby providing an explanation for its association with poor health and mortality.

Prenatal stress, telomere biology, and fetal programming of health and disease risk

A substantial body of epidemiological, clinical, cellular, and molecular evidence converges to suggest that conditions during the intrauterine period of life play a critical role in developmental programming to influence subsequent health and susceptibility for common, complex disorders. Elucidation of the biological mechanisms underlying these effects is an area of considerable interest and investigation, and it is important to determine whether these mechanisms are distinct for different health outcomes or whether there are some common underlying pathways that may account for the effects of disparate prenatal and early postnatal conditions on various health and disease risk phenotypes. We propose that telomere biology may represent a common underlying mechanism connecting fetal programming and subsequent health outcomes. It appears that the initial establishment of telomere length and regulation of telomere homeostasis may be plastic and receptive to the influence of intrauterine and other early life conditions. Moreover, telomere homeostasis in various cell types may serve as a fundamental integrator and regulator of processes underlying cell genomic integrity and function, aging, and senescence over the life span. We advance the hypothesis that context- and time-inappropriate exposures to various forms of physiological stress (maternal-placental-fetal endocrine aberrations and immune, inflammatory, and oxidative stresses) during the intrauterine period of development may alter or program the telomere biology system in a manner that accelerates cellular dysfunction, aging, and disease susceptibility over the life span.

Endothelial dysfunction and hypertension in aging

Hypertension is one of the common diseases in the elderly. The prevalence of hypertension markedly increases with advancing age. Both aging and hypertension have a critical role in cardiovascular and cerebrovascular complications. Although aging and hypertension, either independently or collectively, impair endothelial function, aging and hypertension may have similar cascades for the pathogenesis and development of endothelial dysfunction. Nitric oxide (NO) has an important role in regulation of vascular tone. Decrease in NO bioavailability by endothelial dysfunction would lead to elevation of blood pressure. An imbalance of reduced production of NO or increased production of reactive oxygen species, mainly superoxide, may promote endothelial dysfunction. One possible mechanism by which the prevalence of hypertension is increased in relation to aging may be advancing endothelial dysfunction associated with aging through an increase in oxidative stress. In addition, endothelial cell senescence is also involved in aging-related endothelial dysfunction. In this review, we focus on recent findings and interactions between endothelial function, oxidative stress and hypertension in aging.

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.

Leukocyte telomere length in HIV-infected and HIV-exposed uninfected children: shorter telomeres with uncontrolled HIV viremia

OBJECTIVES

Nucleoside reverse transcriptase inhibitors (NRTIs) used in HIV antiretroviral therapy can inhibit human telomerase reverse transcriptase. We therefore investigated whether in utero or childhood exposure to NRTIs affects leukocyte telomere length (LTL), a marker of cellular aging.

METHODS

In this cross-sectional CARMA cohort study, we investigated factors associated with LTL in HIV-1-infected (HIV(+)) children (n = 94), HIV-1-exposed uninfected (HEU) children who were exposed to antiretroviral therapy (ART) perinatally (n = 177), and HIV-unexposed uninfected (HIV(-)) control children (n = 104) aged 0-19 years. Univariate followed by multivariate linear regression models were used to examine relationships of explanatory variables with LTL for: a) all subjects, b) HIV(+)/HEU children only, and c) HIV(+) children only.

RESULTS

After adjusting for age and gender, there was no difference in LTL between the 3 groups, when considering children of all ages together. In multivariate models, older age and male gender were associated with shorter LTL. For the HIV(+) group alone, having a detectable HIV viral load was also strongly associated with shorter LTL (p = 0.007).

CONCLUSIONS

In this large study, group rates of LTL attrition were similar for HIV(+), HEU and HIV(-) children. No associations between children's LTL and their perinatal ART exposure or HIV status were seen in linear regression models. However, the association between having a detectable HIV viral load and shorter LTL suggests that uncontrolled HIV viremia rather than duration of ART exposure may be associated with acceleration of blood telomere attrition.

Reactive oxygen species formation and apoptosis in human peripheral blood mononuclear cell induced by 900 MHz mobile phone radiation

We demonstrate that reactive oxygen species (ROS) plays an important role in the process of apoptosis in human peripheral blood mononuclear cell (PBMC) which is induced by the radiation of 900 MHz radiofrequency electromagnetic field (RFEMF) at a specific absorption rate (SAR) of ~0.4 W/kg when the exposure lasts longer than two hours. The apoptosis is induced through the mitochondrial pathway and mediated by activating ROS and caspase-3, and decreasing the mitochondrial potential. The activation of ROS is triggered by the conformation disturbance of lipids, protein, and DNA induced by the exposure of GSM RFEMF. Although human PBMC was found to have a self-protection mechanism of releasing carotenoid in response to oxidative stress to lessen the further increase of ROS, the imbalance between the antioxidant defenses and ROS formation still results in an increase of cell death with the exposure time and can cause about 37% human PBMC death in eight hours.

"Is obesity linked to aging?": adipose tissue and the role of telomeres

Obesity is a condition in which excess or abnormal fat accumulation may present with adverse effects on health and decreased life expectancy. Increased body weight and adipose tissue accumulation amplifies the risk of developing various age-related diseases, such as cardiovascular disease, type 2 diabetes mellitus, musculoskeletal disorders, respiratory diseases and certain types of cancer. This imbalance in body composition and body weight is now recognized as a state of increased oxidative stress and inflammation for the organism. Increasing oxidative stress and inflammation affect telomeres. Telomeres are specialized DNA-protein structures found at the ends of eukaryotic chromosomes and serve as markers of biological aging rate. They also play a critical role in maintaining genomic integrity and are involved in age-related metabolic dysfunction. Erosion of telomeres is hazardous to healthy cells, as it is a known mechanism of premature cellular senescence and loss of longevity. The association of telomeres and oxidative stress is evident in cultured somatic cells in vitro, where oxidative stress enhances the process of erosion with each cycle of replication. Shorter telomeres have been associated with increasing body mass index, increased adiposity, and more recently with increasing waist to hip ratio and visceral excess fat accumulation. Furthermore, many of the metabolic imbalances of obesity (e.g. glycemic, lipidemic, etc.) give rise to organ dysfunction in a way that resembles the accelerated aging process. This article is a non-systematic review of the evidence linking obesity and accelerated aging processes as they are regulated by telomeres.

RPE cell senescence: a key contributor to age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in industrialized countries. Although much progress has been made recently in the management of later stages of the disease, no agents have yet been developed for the early stages or for prophylactic use. Furthermore, even the treatments for the later stages have limited effectiveness. The process of developing improved treatments for AMD is complicated by the existence of several theories concerning the cause of the disorder, each suggesting a different strategy for finding effective therapeutics. One of the potential contributors to AMD pathology is retinal pigment epithelial (RPE) cell senescence. The present paper hypothesizes that RPE senescence plays a central role in the etiology of AMD. This hypothesis is supported by the ability of RPE cell senescence to account for the signs, risk factors, and successful treatment modalities of the disorder. This hypothesis also points to several new prophylactic and treatment strategies for AMD.

Short leukocyte telomere length is associated with aortic dissection

BACKGROUND

Aortic dissection is an age-related and lethal vascular disease. Aging, which is associated with degeneration, is the major risk factor of aortic dissection. Telomeres are specialized DNA structures located at the end of eukaryotic chromosomes, the telomere length could be considered as an index of vascular aging. The purpose of present study was undertaken to investigate the relationship between the leukocyte telomere length and aortic dissection.

METHODS AND RESULTS

Seventy-two patients with aortic dissection and seventy-two sex- and age-matched subjects without vascular diseases were collected. Leukocyte telomere length ratio (T/S ratio) was measured using a quantitative PCR method and analyzed. A significantly shorter leukocyte telomere length in the patients with aortic dissection was found compared to the controls, [median 1.02 (interquartile range {IQR}:0.83-1.37) vs median 1.63 [IQR: 1.18-2.51), p<0.001]. The telomere length in the control group showed a trend of inverse correlation with age (r=-0.226, p=0.056), however, there was no significant correlation in aortic dissection (r=0.062, p=0.607). The short leukocyte telomere length was associated with aortic dissection, even after adjustment for other risk factor (OR=0.214, 95% CI: 0.085-0.537).

CONCLUSION

Leukocyte telomere length could be an independent predictor of aortic dissection. Measurement of the leukocyte telomere length may be valuable for patients with a high risk of aortic dissection.