Short Telomere Load, Telomere Length, and Subclinical Atherosclerosis

Clinical and biological markers of premature aging after autologous SCT in childhood cancer

The aim of this study was to analyze the prevalence of frailty and physical health limitations among long-term survivors of high-risk neuroblastoma (HR NBL) and to investigate whether frail health is associated with variables of cardiovascular function, markers of inflammation and telomere length. A national study cohort of 19 (median age 22, range 16-30 years) long-term (>10 years) HR NBL survivors was studied and the findings were compared with 20 age- and sex-matched controls. Frailty was defined as ⩾3 of the following conditions: low muscle mass, low energy expenditure, slow running and weakness. The prevalence of frailty was significantly higher among the HR NBL survivors 9/19 (47%) than among the controls (0%). Thirteen (68%) of the survivors reported significant physical health limitations in vigorous activities, as opposed to none of the controls. The HR NBL survivors had significantly shorter telomere length and higher serum levels of high sensitivity C-reactive protein than did the controls. Frail health and poor physical functioning are prevalent among HR NBL survivors and suggest premature aging. Survivors with gonadal damage, very low fat mass percentage, low glycosylated hemoglobin A1c and increased common carotid artery intima-media thickness may be more prone to early aging after high dose therapy.

Telomere Shortening, Regenerative Capacity, and Cardiovascular Outcomes

RATIONALE

Leukocyte telomere length (LTL) is a biological marker of aging, and shorter LTL is associated with adverse cardiovascular outcomes. Reduced regenerative capacity has been proposed as a mechanism. Bone marrow-derived circulating progenitor cells are involved in tissue repair and regeneration.

OBJECTIVE

Main objective of this study was to examine the relationship between LTL and progenitor cells and their impact on adverse cardiovascular outcomes.

METHODS AND RESULTS

We measured LTL by quantitative polymerase chain reaction in 566 outpatients (age: 63±9 years; 76% men) with coronary artery disease. Circulating progenitor cells were enumerated by flow cytometry. After adjustment for age, sex, race, body mass index, smoking status, and previous myocardial infarction, a shorter LTL was associated with a lower CD34⁺ cell count: for each 10% shorter LTL, CD34⁺ levels were 5.2% lower (P<0.001). After adjustment for the aforementioned factors, both short LTL (<Q1) and low CD34+ levels (<Q1) predicted adverse cardiovascular outcomes (death, myocardial infarction, coronary revascularization, or cerebrovascular events) independently of each other, with a hazard ratio of 1.8 and 95% confidence interval of 1.1 to 2.0, and a hazard ratio of 2.1 and 95% confidence interval of 1.3 to 3.0, respectively, comparing Q1 to Q2-4. Patients who had both short LTL (<Q1) and low CD34+ cell count (<Q1) had the greatest risk of adverse outcomes (hazard ratio =3.5; 95% confidence interval, 1.7-7.1).

CONCLUSIONS

Although shorter LTL is associated with decreased regenerative capacity, both LTL and circulating progenitor cell levels are independent and additive predictors of adverse cardiovascular outcomes in coronary artery disease patients. Our results suggest that both biological aging and reduced regenerative capacity contribute to cardiovascular events, independent of conventional risk factors.