Journals of Gerontology Series A: Biological Sciences and Medical Sciences Large Type Edition
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Benetos, A.
Right arrow Articles by Aviv, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Benetos, A.
Right arrow Articles by Aviv, A.
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 60:1593-1596 (2005)
© 2005 The Gerontological Society of America

Aldosterone and Telomere Length in White Blood Cells

Athanase Benetos1,, Jeffrey P. Gardner2, Masayuki Kimura2, Carlos Labat1, Rosine Nzietchueng1, Brigitte Dousset1, Faiez Zannad1, Patrick Lacolley1 and Abraham Aviv2

1 INSERM Unit 684, University of Nancy, France.
2 Hypertension Research Center, University of Medicine and Dentistry of New Jersey, Newark.

Address correspondence to Athanase Benetos, MD, PhD, Centre de Geriatrie, Hôpital Brabois, University of Nancy, 54511 Nancy-les-Vandoeuvre, France. E-mail: a.benetos{at}chu-nancy.fr


   Abstract
Top
 Abstract
Materials and Methods
 Results
 Discussion
 References
 
Background. Aldosterone accelerates cardiovascular aging by mechanisms that generate reactive oxygen species. Telomere length in white blood cells (WBCs) may be a bioindicator that registers the accruing burden of systemic oxidative stress. The aim of the present study was, therefore, to examine the relationship between plasma aldosterone and telomere length in WBCs.

Methods. We studied 75 normotensive and never-treated mildly hypertensive men whose blood was drawn for the measurements of plasma aldosterone concentration and the terminal restriction fragment (TRF) length in WBCs.

Results. The slope of the TRF–age relationship in the entire cohort showed a decrease in telomere length of 26 ± 5 base pairs per year (r = –0.46, p <.001). Age-adjusted TRF length was the longest in the lowest aldosterone quartile (6.74 ± 0.12 kb) and shortest in the highest aldosterone quartile (6.36 ± 0.11 kb), with intermediate TRF lengths in the second and third aldosterone quartiles (analysis of variance [ANOVA] trend test, p =.025). In telomeric attrition equivalence, participants in the upper aldosterone quartile were 15 years older than their peers in the lowest quartile.

Conclusions. The inverse relationship between aldosterone and WBC telomere length suggests not only that aldosterone is pro-oxidant but that elevated concentrations of this hormone might be linked to a higher rate of telomere attrition and perhaps increased biological aging in humans.

THE present consensus is that both oxidative stress (1) and inflammation (2) are key elements in the pathophysiology of age-related cardiovascular disease (CVD) in humans. This tenet is based on studies showing that indices of oxidative stress and inflammation are elevated in individuals prone to and patients with CVD. It is noteworthy, however, that these indices usually express the state of the moment of oxidative stress and/or inflammation. What's more, it might be difficult to dissociate oxidative stress from inflammation, as oxidative stress evokes inflammation and vice versa. An index that captures the accruing burden rather the acute state of oxidative stress and/or inflammation might be a powerful predictor of cardiovascular risks. For the following reasons, white blood cell (WBC) telomere dynamics (expressed by telomere length and attrition rate) may be such an index. First, telomeres undergo attrition with each cellular replication and their rate of loss is augmented by oxidative stress (3–5). Second, inflammation entails an increase in WBC turnover rate, which would further increase telomere attrition in these cells. Thus, WBC telomere dynamics probably chronicles the burden of oxidative stress and/or inflammation over the individual's life span. Indeed, several studies (6–10) have demonstrated that WBC telomeres are shorter in persons susceptible to or expressing CVD.

In the present study we focus on the link between circulating aldosterone and WBC telomere length because aldosterone is an established pro-oxidant, generating oxidative stress in the vasculature (11), heart (12), kidney (13), and WBCs (14). Moreover, several clinical results suggest that elevated levels of aldosterone denote a propensity for CVD in humans (15–17).


   MATERIALS AND METHODS
Top
 Abstract
 Materials and Methods
Results
 Discussion
 References
 
Participants
Seventy-five males undergoing a 5-year periodical health evaluation at the Centre d'Investigations Préventives et Cliniques (IPC) were included in this study. The IPC is one of the largest medical facilities in France that provides working and retired persons a free medical examination every 5 years (9). Because antihypertensive treatment can influence aldosterone levels, only participants who had never been treated for hypertension were included in this analysis. Thus, we included 75 consecutive men who were not treated for hypertension and who, in addition to the standard health check-up, had measurements of plasma aldosterone and WBC telomere length. Among these men, 56% were normotensive and 44% had mild to moderate untreated hypertension.

Medical History, Blood Pressure, and Biochemical Measurements
Participants answered a standardized questionnaire, which provided information about demographic background, occupation, medical history, drug use, and personal habits. Thereafter, using a manual sphygmomanometer, the same two physicians measured (under constant temperature of 19°C–21°C) supine blood pressure (BP) in the right arm. Fasting blood samples were then collected after 10–15 minutes of rest in a sitting position. Blood was used for DNA extractions, standard biochemical tests, and plasma aldosterone measurements.

Measurements of WBC Telomere Length by Terminal Restriction Fragment Length
DNA samples, extracted from WBCs and DNA samples were digested overnight with restriction enzymes HinfI (10 U) and RsaI (10 U) (Boehringer Mannheim, Mannheim, Germany). Eighteen DNA samples (~5 µg each) and four DNA ladders (1 kb DNA ladder plus {lambda} DNA/HindIII fragments; Gibco, Carlsbad, CA) were resolved on a 0.5% agarose gel (20 cm x 20 cm) at 50 V (GNA-200; Pharmacia Biotech, Piscataway, NJ). After 16 hours, the DNA was depurinated for 30 minutes in 0.25 N HCl, denatured 30 minutes in 0.5 mol/L NaOH/1.5 mol/L NaCl, and neutralized for 30 minutes in 0.5 mol/L Tris, pH 8/1.5M NaCl. The DNA was transferred for 1 hour to a positively charged nylon membrane (Boehringer Mannheim) using a vacuum blotter (Appligene Oncor, Feasterville, PA). The membranes were hybridized at 65°C with the telomeric probe [digoxigenin 3'-end labeled 5'-(CCTAAA)3] overnight in 5x sodium saline citrate (SSC), 0.1% Sarkosyl, 0.02% sodium dodecyl sulfate, and 1% blocking reagent (Boehringer Mannheim). The membranes were washed 3 times at room temperature in 2x SSC, 0.1% sodium dodecyl sulfate each for 15 minutes, and once in 2x SSC for 15 minutes. The digoxigenin-labeled probe was detected by the digoxigenin luminescent detection procedure (Boehringer Mannheim) and exposed on x-ray film. Each DNA sample was measured in triplicate. The intra-assay coefficient of variation of this measurement is less than 2%.

Measurements were performed blindly; each sample was identified by a number. Results (means of duplicate measurements) were transmitted to CL for statistical analysis.

Plasma Aldosterone Radioimmunoassay
A radioimmunoassay kit (Immunotech SA, Marseille, France) was used to measure plasma aldosterone. Samples (50 µl) and standards (50 µl) were incubated with 125I-labeled aldosterone, as tracer, in antibody-coated tubes. After 3 hours of incubation at room temperature with shaking, the liquid content of each tube was aspirated and bound radioactivity was measured. Sample values were determined against a standard curve. The values were expressed in pg/ml. The intra-assay coefficient of variation evaluated for this assay is less than 9.5%.

Statistical Analysis
The association between plasma aldosterone concentration and terminal restriction fragment (TRF) length (age-adjusted) was tested using univariate and multivariate analyses. Aldosterone concentration was log-transformed (because of a skewed distribution) and treated as a categorical entity, expressed in quartiles, or as a continuous entity. Multivariate models were adjusted for age and other covariates. The association between aldosterone quartiles and TRF length was tested using a trend test analysis of variance. A two-sided p value of less than.05 was considered to be statistically significant. All statistics were performed using SAS statistical software (SAS Institute, Cary, NC). Data in Table 1 are presented as mean ± standard deviation. Adjusted mean values are presented as mean ± standard error of the mean.


View this table:
[in this window]
[in a new window]
  		Table 1. Characteristics of the Population According to the Aldosterone Quartiles (Mean ± SD).

 

   RESULTS
Top
 Abstract
 Materials and Methods
 Results
Discussion
 References
 
Table 1 displays relevant clinical and laboratory data (without adjustment for age), stratified according to the quartiles of plasma aldosterone concentrations. Age, body mass index, BP, plasma creatinine, and serum potassium were similar in the aldosterone quartiles, whereas the heart rate (HR) was higher and the TRF was lower in participants belonging to the higher aldosterone quartiles. Age was negatively correlated with telomere length; the slope of TRF–age relationship showed a mean decrease in telomere length of 26 ± 5 base pairs per year (r = –0.46, p <.001; Figure 1). After adjustment for age, TRF length (Figure 2) was the longest in the lowest aldosterone quartile (6.74 ± 0.12 kb) and the shortest in the highest aldosterone quartile (6.36 ± 0.11), with intermediate TRF lengths in the second and third aldosterone quartiles (6.55 ± 0.12 and 6.45 ± 0.12, respectively) (analysis of variance trend test, p =.025). The association between age-adjusted TRF length and aldosterone concentration was also observed when aldosterone was treated as a continuous variable (log aldosterone vs age-adjusted TRF length r = –0.28, p =.02; Figure 3). TRF length was not associated with either HR or BP levels in either univariate or multivariate analyses.


Figure 01
View larger version (14K):
[in this window]
[in a new window]
  		Figure 1. Relation between age and terminal restriction fragment (TRF) length. TRF length in kilobase pairs (kb) = –0.026 * Age (y) + 7.97; R2 = 0.211, p <.001

 

Figure 02
View larger version (16K):
[in this window]
[in a new window]
  		Figure 2. Age-adjusted terminal restriction fragment (TRF) length stratified according to aldosterone quartiles. Quartile 1 represents the lowest plasma aldosterone levels and Quartile 4 corresponds to the highest aldosterone levels. The trend analysis of variance test showed an inverse relationship between the aldosterone quartiles and TRF length; p = .025. MAP = mean arterial pressure

 

Figure 03
View larger version (17K):
[in this window]
[in a new window]
  		Figure 3. Relationship between plasma aldosterone and age-adjusted terminal restriction fragment (TRF) length. TRF length in kilobase pairs (kb) = –0.609 * LogALDO (aldosterone) (pg/mmol) + 7.60; R2 = 0.072, p =.02

 

   DISCUSSION
Top
 Abstract
 Materials and Methods
 Results
 Discussion
References
 
Oxidative stress and inflammation are central to theories of aging (18,19). WBC telomere length may be a bioindicator of aging if it records the cumulative burden of oxidative stress and inflammation (20). Our study shows that WBC telomere length is shorter in men with high plasma aldosterone levels. From the biological standpoint, individuals with shorter age-adjusted telomere length might be regarded as older than their chronological age would indicate. The difference in TRF length between the lowest and the highest aldosterone quartiles was 0.38 kb (380 base pairs). As the telomere attrition for the entire cohort was 26 base pairs per year, this difference in telomere length between the highest and lowest aldosterone quartiles corresponds to approximately 15 years in telomere attrition equivalence, meaning that from the standpoint of telomere dynamics, participants in the highest aldosterone quartile are considerably older than their peers in the lowest quartile.

Recently, Vasan and coworkers (15) reported that higher aldosterone levels are associated with predilection to hypertension. In the present study we did not find a significant association between plasma aldosterone and BP levels, though as shown in Table 1, BP was lower in participants belonging to the lowest aldosterone quartile. In addition, participants with higher aldosterone had higher HR. However, the association between aldosterone and telomere length cannot be explained by these hemodynamic differences in the aldosterone quartiles, because neither BP nor HR were associated with TRF in univariate analyses. Adjustment for BP or HR in multivariate analyses did not modify the association between aldosterone and telomere length.

Aldosterone is a determinant in the pathogenesis of CVD and in accelerating cardiovascular aging in that it is a major stimulator of cardiac and vascular collagen synthesis (21). The presence of aldosterone receptors in large arteries, particularly the aorta (22), and the endogenous vascular synthesis of aldosterone (23) are in line with these findings. Pharmacological blockade of the aldosterone receptors reduces arterial fibrosis associated with aging in normotensive (24) and genetically hypertensive (25) rats, providing further support for the role of aldosterone in vascular aging in laboratory animals. In addition, aldosterone blockade significantly decreases cardiovascular morbidity and mortality in heart failure and in postinfarction patients (16,17). Collectively, these studies suggest that increased aldosterone levels may be linked to an accelerated biological aging of the cardiovascular system. As aldosterone is a powerful pro-oxidant in a variety of tissues and cells (11–14), it is reasonable to propose that an increase in oxidative stress and perhaps inflammation are the likely causes for the shortened WBC TRF length in participants with increased aldosterone levels.

Conclusion
This study suggests that persons with higher plasma aldosterone levels have a more advanced biological age than do their peers of the same age with low aldosterone levels—a phenomenon that may be the outcome of a greater increase in the cumulative burden of oxidative stress. Longitudinal studies that include measurements of oxidative stress in conjunction with aldosterone and WBC telomere length will be essential to gaining a better understanding of the links between aldosterone and telomere dynamics.


   Acknowledgments
Top
 Abstract
 Materials and Methods
 Results
 Discussion
 References
 
This study was supported by the National Institute of Medical Research (INSERM), the French public health care system (CNAM), the National Institutes of Health (grant AG021593), and the Healthcare Foundation of New Jersey; no private funding was provided.


   Footnotes
Top
 Abstract
 Materials and Methods
 Results
 Discussion
 References
 
Decision Editor: Luigi Ferrucci, MD, PhD

Received February 24, 2005

Accepted May 16, 2005


   References
Top
 Abstract
 Materials and Methods
 Results
 Discussion
 References
 

  1. Stocker R, Keaney JF, Jr. Role of oxidative modifications in atherosclerosis. Physiol Rev. 2004;84:1381-1487.[Abstract/Free Full Text]
  2. Granger DN, Vowinkel T, Petnehazy T. Modulation of the inflammatory response in cardiovascular disease. Hypertension. 2004;43:924-931.[Abstract/Free Full Text]
  3. Harley CB, Futcher AB, Greider CW. Telomeres shorten during ageing of human fibroblasts. Nature. 1990;345:458-460.[Medline]
  4. Chang E, Harley CB. Telomere length and replicative aging in human vascular tissues. Proc Natl Acad Sci U S A. 1995;92:11190-11194.[Abstract/Free Full Text]
  5. von Zglinicki T. Oxidative stress shortens telomeres. Trends Biochem Sci. 2002;27:339-344.[Medline]
  6. Okuda K, Khan MY, Skurnick J, Kimura M, Aviv H, Aviv A. Telomere attrition of the human abdominal aorta: relationships with age and atherosclerosis. Atherosclerosis. 2000;152:391-398.[Medline]
  7. Samani NJ, Boultby R, Butler R, Thompson JR, Goodall AH. Telomere shortening in atherosclerosis. Lancet. 2001;358:472-473.[Medline]
  8. Benetos A, Okuda K, Lajemi M, et al. Telomere length as an indicator of biologic aging: the gender effect and relation with pulse pressure and pulse wave velocity. Hypertension. 2001;37:(pt 2): 381-385.[Abstract/Free Full Text]
  9. Benetos A, Gardner JP, Zureik M, et al. Short telomeres are associated with increased carotid atherosclerosis in hypertensive subjects. Hypertension. 2004;43:182-185.[Abstract/Free Full Text]
  10. Gardner JP, Li S, Srinivasan SR, et al. Rise in insulin resistance is associated with telomere attrition. Circulation. 2005;111:2171-2177.[Abstract/Free Full Text]
  11. Pu Q, Neves MF, Virdis A, Touyz RM, Schiffrin E. Endothelin antagonism on aldosterone-induced oxidative stress and vascular remodeling. Hypertension. 2003;42:49-55.[Abstract/Free Full Text]
  12. Park YM, Park MY, Suh YL, Park JB. NAD(P)H oxidase inhibitor prevents blood pressure elevation and cardiovascular hypertrophy in aldosterone-infused rats. Biochem Biophys Res Commun. 2004;313:812-817.[Medline]
  13. Nishiyama A, Yao L, Nagai Y, et al. Possible contributions of reactive oxygen species and mitogen-activated protein kinase to renal injury in aldosterone/salt-induced hypertensive rats. Hypertension. 2004;24:841-848.
  14. Keidar S, Kaplan M, Pavlotzky E, et al. Aldosterone administration to mice stimulates macrophage NADPH oxidase and increases atherosclerosis development. Circulation. 2004;109:2213-2220.[Abstract/Free Full Text]
  15. Vasan RS, Evans JC, Larson MG, et al. Serum aldosterone and incidence of hypertension in nonhypertensive persons. N Engl J Med. 2004;351:33-41.[Abstract/Free Full Text]
  16. Pitt B, Zannad F, Remme WJ, Cody R, Castaigne A, Perez A. The effect of spironolactone on morbidity and mortality in patients with severe heart failure. Randomized Aldactone Evaluation Study Investigators. N Engl J Med. 1999;341:709-717.[Abstract/Free Full Text]
  17. Pitt B, Remme W, Zannad F, et al. Eplerenone, a selective aldosterone blocker, in patients with left ventricular dysfunction after myocardial infarction. N Engl J Med. 2003;348:1309.[Abstract/Free Full Text]
  18. Finkel T, Holbrook NJ. Oxidants, oxidative stress and the biology of aging. Nature. 2000;508:239-247.
  19. Finch C, Crimmins EM. Inflammatory exposure and historical changes in human life-spans. Science. 2004;305:1736-1739.[Abstract/Free Full Text]
  20. Aviv A. telomeres and human aging: facts and fibs. Sci Aging Knowledge Environ. 2004;51:pe43.
  21. Brilla CG, Weber KT. Reactive and reparative myocardial fibrosis in arterial hypertension in the rat. Cardiovasc Res. 1992;26:671-677.[Abstract/Free Full Text]
  22. Lombes M, Oblin ME, Gasc JM, Baulieu EE, Farman N, Bonvalet JP. Immunohistochemical and biochemical evidence for a cardiovascular mineralocorticoid receptor. Circ Res. 1992;71:503-510.[Abstract/Free Full Text]
  23. Takeda Y, Miyamori I, Yoneda T, et al. Production of aldosterone in isolated rat blood vessels. Hypertension. 1995;25:170-173.[Abstract/Free Full Text]
  24. Lacolley P, Safar M, Lucet B, Ledudal K, Labat C, Benetos A. Prevention of aortic and cardiac fibrosis by spironolactone in old normotensive rats. J Am Coll Cardiol. 2001;37:662-667.[Abstract/Free Full Text]
  25. Benetos A, Lacolley P, Safar M. Prevention of aortic fibrosis by spironolactone in spontaneously hypertensive rats. Arterioscler Thromb Vasc Res. 1997;17:1152-1156.[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 CirculationHome page
R. S. Vasan, S. Demissie, M. Kimura, L. A. Cupples, N. Rifai, C. White, T. J. Wang, J. P. Gardner, X. Cao, E. J. Benjamin, et al.
Association of Leukocyte Telomere Length With Circulating Biomarkers of the Renin-Angiotensin-Aldosterone System: The Framingham Heart Study
Circulation, March 4, 2008; 117(9): 1138 - 1144.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Benetos, A.
Right arrow Articles by Aviv, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Benetos, A.
Right arrow Articles by Aviv, A.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
All GSA journals The Gerontologist
Journals of Gerontology Series B: Psychological Sciences and Social Sciences