Identification of serum biomarkers for aging and anabolic response

Banerjee Camellia, Ulloor Jagadish, Dillon, Dahodwala Qusai, Franklin Brittani, Storer Thomas, Sebastiani Paola, Sheffield-Moore Melinda, Urban, Bhasin Shalender, Montano Monty

Description

Objective With the progressive aging of the human population, there is an inexorable decline in muscle mass, strength and function. Anabolic supplementation with testosterone has been shown to effectively restore muscle mass in both young and elderly men. In this study, we were interested in identifying serum factors that change with age in two distinct age groups of healthy men, and whether these factors were affected by testosterone supplementation. Methods We measured the protein levels of a number of serum biomarkers using a combination of banked serum samples from older men (60 to 75 years) and younger men (ages 18 to 35), as well as new serum specimens obtained through collaboration. We compared baseline levels of all biomarkers between young and older men. In addition, we evaluated potential changes in these biomarker levels in association with testosterone dose (low dose defined as 125 mg per week or below compared to high dose defined as 300 mg per week or above) in our banked specimens. Results We identified nine serum biomarkers that differed between the young and older subjects. These age-associated biomarkers included: insulin-like growth factor (IGF1), N-terminal propeptide of type III collagen (PIIINP), monokine induced by gamma interferon (MIG), epithelial-derived neutrophil-activating peptide 78 (ENA78), interleukin 7 (IL-7), p40 subunit of interleukin 12 (IL-12p40), macrophage inflammatory protein 1β (MIP-1β), platelet derived growth factor β (PDGFβ) and interferon-inducible protein 10 (IP-10). We further observed testosterone dose-associated changes in some but not all age related markers: IGF1, PIIINP, leptin, MIG and ENA78. Gains in lean mass were confirmed by dual energy X-ray absorptiometry (DEXA). Conclusions Results from this study suggest that there are potential phenotypic biomarkers in serum that can be associated with healthy aging and that some but not all of these biomarkers reflect gains in muscle mass upon testosterone administration.

Sujets

• Testostérone
• Agé
• Biomarker

Informations

• Publié par: biomed
• Publié le: 01 janvier 2011
• Nombre de lectures: 11
• Langue: English

Extrait

Banerjee et al. Immunity & Ageing 2011, 8:5
http://www.immunityageing.com/content/8/1/5 IMMUNITY & AGEING
RESEARCH Open Access
Identification of serum biomarkers for aging and
anabolic response
1 2 3 1 1 2Camellia Banerjee , Jagadish Ulloor , Edgar L Dillon , Qusai Dahodwala , Brittani Franklin , Thomas Storer ,
3 4 4 2 1*Paola Sebastiani , Melinda Sheffield-Moore , Randall J Urban , Shalender Bhasin and Monty Montano
Abstract
Objective: With the progressive aging of the human population, there is an inexorable decline in muscle mass,
strength and function. Anabolic supplementation with testosterone has been shown to effectively restore muscle
mass in both young and elderly men. In this study, we were interested in identifying serum factors that change
with age in two distinct age groups of healthy men, and whether these factors were affected by testosterone
supplementation.
Methods: We measured the protein levels of a number of serum biomarkers using a combination of banked
serum samples from older men (60 to 75 years) and younger men (ages 18 to 35), as well as new serum
specimens obtained through collaboration. We compared baseline levels of all biomarkers between young and
older men. In addition, we evaluated potential changes in these biomarker levels in association with testosterone
dose (low dose defined as 125 mg per week or below compared to high dose defined as 300 mg per week or
above) in our banked specimens.
Results: We identified nine serum biomarkers that differed between the young and older subjects. These age-
associated biomarkers included: insulin-like growth factor (IGF1), N-terminal propeptide of type III collagen (PIIINP),
monokine induced by gamma interferon (MIG), epithelial-derived neutrophil-activating peptide 78 (ENA78),
interleukin 7 (IL-7), p40 subunit of interleukin 12 (IL-12p40), macrophage inflammatory protein 1b (MIP-1b), platelet
derived growth factor b (PDGFb) and interferon-inducible protein 10 (IP-10). We further observed testosterone
dose-associated changes in some but not all age related markers: IGF1, PIIINP, leptin, MIG and ENA78. Gains in lean
mass were confirmed by dual energy X-ray absorptiometry (DEXA).
Conclusions: Results from this study suggest that there are potential phenotypic biomarkers in serum that can be
associated with healthy aging and that some but not all of these biomarkers reflect gains in muscle mass upon
testosterone administration.
Keywords: Testosterone, Age, Biomarker
Introduction [5-8]. Biomarkers for healthy aging identifiable in the
As the general population ages, there is an increased serum would be of substantial use in detecting age asso-
prevalence of loss in muscle mass, raising the risk for ciated morbidities and initiating therapeutic pro-ana-
frailty, declines in functional mobility, and early mortal- bolic treatment.
ity[1-4].Lossofleanmusclecanalsobeacomorbid Anabolic supplementation is broadly recognized to
condition in multiple chronic and acute disorders increase muscle mass in both elderly and young indivi-
including cancer cachexia, HIV-associated weight loss, duals [9,10]. Testosterone displays a dose dependent
inflammatory sepsis, and age-associated sarcopenia effect on gains of lean muscle mass and cross-sectional
fiber area in both older and younger men [6,9,11-15].
However, because in some populations testosterone
* Correspondence: [e-mail]
1 administration poses undesirable side effects, there is aSection of Infectious Diseases, Department of Medicine, Boston University
School of Medicine, 710 Albany Street, Boston MA, 02118, USA motivation for identifying alternative, broadly effective
Full list of author information is available at the end of the article
© 2011 Banerjee et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.Banerjee et al. Immunity & Ageing 2011, 8:5 Page 2 of 7
http://www.immunityageing.com/content/8/1/5
anabolic therapeutics, such as selective androgen recep- Sealy Center of Aging Volunteer Registry at the Univer-
tor modulators (SARMs) that improve muscle mass and sity of Texas Medical Branch (UTMB) in Galveston, TX
physical function [16-18]. Therefore, the utility of serum for inclusion in a randomized double-blinded placebo-
biomarkers would help to gauge pro-anabolic activity of controlled testosterone intervention study. All subjects
SARMs and therefore be of substantial value in clinical provided informed written consent according to the
research to ameliorate declines in muscle mass and guidelines established by the UTMB institutional review
function. board and were medically screened. Qualified subjects
In this study we were interested in identifying age- had endogenous testosterone concentrations below 500
associated biomarkers for healthy aging and evaluating ng/dL and were otherwise healthy. To assess medical
whether biomarkers that differ between healthy young eligibility, subjects underwent a battery of tests including
and older men at baseline, also differ in response to a history and physical examination, complete blood
graded doses of testosterone. To achieve this, we used count, metabolic panel including fasting serum glucose
banked serum specimens from younger and older men and insulin, an electrocardiogram (ECG), plasma elec-
to measure selected soluble cytokines and growth fac- trolytes, prostate specific antigen (PSA), liver and renal
tors, based on predicted biomarkers from previous stu- function and lipid panel. Subjects were included based
dies by us and others [2,15,19-25]. Herein, we report upon their ability to provide regular transportation to
results from this pilot analysis to identify biomarkers the Clinical Research Center (CRC) at UTMB. Subject
that change either in association with age and/or testos- exclusion criteria included the following: 1) serum tes-
terone dosage. tosterone > 500 ng/dL, 2) indication of cardiovascular
disease or heart problems assessed via a resting ECG
Methods and a Bruce protocol exercise stress test, 3) previous
Sample Population (Boston, MA) history of angina or myocardial infarction, 4) PSA > 4.0
The samples used for this study were obtained from a μg/L, 5) history of prostate cancer, 6) history of severe
previously reported double-blind, randomized study that benign prostatic hypertrophy, 7) LDL > 200 mg/dL, 8)
consisted of a 4-week control period, 20-week treatment hematocrit > 51%, 9) hypertension (>140/90 mmHg),
period and 16-week recovery period [11,13]. Participants 10) BMI > 35, 11) history of hepatitis or 3 × elevation
included sixty young men (age range 18 to 35 years) of Alk phos, ALT, AST, 12) illnesses including diabetes,
and sixty-one older men (age range 60 to 75 years). All cancer, COPD, sleep apnea or any other causing disabil-
subjects provided informed written consent according to ity, 13) bone related disorders, 14) DEXA lumbar score
protocol approved by the Charles Drew University and > -2.5, 15) currently taking Coumadin, glucocorticoids,
Research and Education Institute. Exclusion criteria androgens, or anti-bone-resorptive agents, and 16) regu-
included 1) presence of prostate disease defined as can- lar physical exercise. These inclusion/exclusion criteria
cer, an American Urological Association symptom score reflect those recommended by the Clinical Guidelines
of greater than 7, a prostate-specific antigen level greater Subcommittee Task Force of The Endocrine Society[26]
than 4 ng/ml, 2) hematocrit above 48%, 3) diabetes mel- and previously published trials with testosterone and
litus, 4) heart problems including myocardial infarction older men [27,28]. Mean baseline testosterone levels for
or congestive heart failure all measured using a 12-lead these older men were 320 ng/dL.
electrocardiogram monitoring to exclude symptoms pre-
sent during exercise as well, 5) severe sleep apena, 6) Testosterone supplementation (Boston, MA)
administration of androgenic steroids in the past year, Serum samples were obtained from men who partici-
7) participation in sports events, resistance training or pated in a randomized testosterone supplementation
moderate to heavy endurance exercise training and 8) trial. Men were treated with monthly injections of a
baseline testosterone levels below 300 ng/dL. For more long-acting GnRH agonist (Lupron depot, 7.5 mg; TAP,
in depth description of enrollment criteria and physical North Chicago, IL) to suppress endogenous testosterone
function, see Bhasin et al, in [11,13]. Stored serum sam- production, and concomitantly weekly injections of one
ples at baseline and after treatment were used from 20 of five doses of testosterone enanthate (Delastryl, Savi-
of the younger men and 19 of the older men based on ent Pharmaceuticals, NJ) [11]. Based on dichotomous
availability. Mean baseline testosterone levels for functional outcomes in previous reports, testosterone
younger men were 586 ng/dL and 358 ng/dL for older doses were categorized as low (i.e., 25 mg, 50 mg, and
men. 125 mg) and high (i.e., 300 mg and 600 mg).
Sample Population (Houston, TX) Biomarker measurements
Stored baseline serum samples were used from 20 older The serum specimens were selected based on quality
men (age range 60 to 85