Dataset Information

Impact of age on the relationships of brown adipose tissue with sex and adiposity in humans.

ABSTRACT:

Objective

Brown adipose tissue (BAT) regulates energy homeostasis and fat mass in mammals and newborns and, most likely, in adult humans. Because BAT activity and BAT mass decline with age in humans, the impact of BAT on adiposity may decrease with aging. In the present study we addressed this hypothesis and further investigated the effect of age on the sex differences in BAT activity and BAT mass.

Research design and methods

Data from 260 subjects (98 with BAT and 162 study date-matched control subjects) who underwent (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) under thermoneutral conditions were analyzed. BAT activity and BAT mass were determined in the upper body.

Results

BAT activity and BAT mass were higher in female (1.59 +/- 0.10 and 32 +/- 5 g vs. 1.02 +/- 0.10 and 18 +/- 4 g, both P < or = 0.0006) than in male subjects. In multivariate analyses, sex (P < 0.0001), age (P < 0.0001), and BMI (P = 0.0018) were associated independently with BAT activity. Interestingly, only in male subjects was there an interaction between BMI and age in determining BAT activity (P = 0.008) and BAT mass (P = 0.0002); BMI decreased with increasing BAT activity and BAT mass in the lowest age tertile (Spearman rank correlation coefficient r(s) = -0.38, P = 0.015 and r(s) = -0.37, P = 0.017, respectively), not in the higher age tertiles. Furthermore, BAT activity and mass differed between female and male subjects only in the upper two age tertiles (all P < or = 0.09).

Conclusions

Our data corroborate that, in general, BAT activity and BAT mass are elevated in female subjects and in younger people. Importantly, we provide novel evidence that the impact of BAT activity and BAT mass on adiposity appears to decline with aging only in male subjects. Furthermore, while BAT activity and BAT mass only moderately decline with increasing age in female subjects, a much stronger effect is found in male subjects.

SUBMITTER: Pfannenberg C

PROVIDER: S-EPMC2889780 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature

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Publications

Impact of age on the relationships of brown adipose tissue with sex and adiposity in humans.

Pfannenberg Christina C Werner Matthias K MK Ripkens Sabine S Stef Irina I Deckert Annette A Schmadl Maria M Reimold Matthias M Häring Hans-Ulrich HU Claussen Claus D CD Stefan Norbert N

Diabetes 20100331 7

<h4>Objective</h4>Brown adipose tissue (BAT) regulates energy homeostasis and fat mass in mammals and newborns and, most likely, in adult humans. Because BAT activity and BAT mass decline with age in humans, the impact of BAT on adiposity may decrease with aging. In the present study we addressed this hypothesis and further investigated the effect of age on the sex differences in BAT activity and BAT mass.<h4>Research design and methods</h4>Data from 260 subjects (98 with BAT and 162 study date- ...[more]

PMID: 20357363

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Project description:Background/objectivesThe presence of T lymphocytes in human adipose tissue has only recently been demonstrated and relatively little is known of their potential relevance in the development of obesity-related diseases. We aimed to further characterise these cells and in particular to investigate how they interact with modestly increased levels of adiposity typical of common overweight and obesity.Subjects/methodsSubcutaneous adipose tissue and fasting blood samples were obtained from healthy males aged 35-55 years with waist circumferences in lean (<94?cm), overweight (94-102?cm) and obese (>102?cm) categories. Adipose tissue-resident CD4+ and CD8+ T lymphocytes together with macrophages were identified by gene expression and flow cytometry. T lymphocytes were further characterised by their expression of activation markers CD25 and CD69. Adipose tissue inflammation was investigated using gene expression analysis and tissue culture.ResultsParticipants reflected a range of adiposity from lean to class I obesity. Expression of CD4 (T-helper cells) and CD68 (macrophage), as well as FOXP3 RNA transcripts, was elevated in subcutaneous adipose tissue with increased levels of adiposity (P<0.001, P<0.001 and P=0.018, respectively). Flow cytometry revealed significant correlations between waist circumference and levels of CD25 and CD69 expression per cell on activated adipose tissue-resident CD4+ and CD8+ T lymphocytes (P-values ranging from 0.053 to <0.001). No such relationships were found with blood T lymphocytes. This increased T lymphocyte activation was related to increased expression and secretion of various pro- and anti-inflammatory cytokines from subcutaneous whole adipose tissue explants.ConclusionsThis is the first study to demonstrate that even modest levels of overweight/obesity elicit modifications in adipose tissue immune function. Our results underscore the importance of T lymphocytes during adipose tissue expansion, and the presence of potential compensatory mechanisms that may work to counteract adipose tissue inflammation, possibly through an increased number of T-regulatory cells.

Project description:BackgroundObesity results from an imbalance between energy intake and expenditure. In rodents and newborn humans, brown adipose tissue helps regulate energy expenditure by thermogenesis mediated by the expression of uncoupling protein 1 (UCP1), but brown adipose tissue has been considered to have no physiologic relevance in adult humans.MethodsWe analyzed 3640 consecutive (18)F-fluorodeoxyglucose ((18)F-FDG) positron-emission tomographic and computed tomographic (PET-CT) scans performed for various diagnostic reasons in 1972 patients for the presence of substantial depots of putative brown adipose tissue. Such depots were defined as collections of tissue that were more than 4 mm in diameter, had the density of adipose tissue according to CT, and had maximal standardized uptake values of (18)F-FDG of at least 2.0 g per milliliter, indicating high metabolic activity. Clinical indexes were recorded and compared with those of date-matched controls. Immunostaining for UCP1 was performed on biopsy specimens from the neck and supraclavicular regions in patients undergoing surgery.ResultsSubstantial depots of brown adipose tissue were identified by PET-CT in a region extending from the anterior neck to the thorax. Tissue from this region had UCP1-immunopositive, multilocular adipocytes indicating brown adipose tissue. Positive scans were seen in 76 of 1013 women (7.5%) and 30 of 959 men (3.1%), corresponding to a female:male ratio greater than 2:1 (P<0.001). Women also had a greater mass of brown adipose tissue and higher (18)F-FDG uptake activity. The probability of the detection of brown adipose tissue was inversely correlated with years of age (P<0.001), outdoor temperature at the time of the scan (P=0.02), beta-blocker use (P<0.001), and among older patients, body-mass index (P=0.007).ConclusionsDefined regions of functionally active brown adipose tissue are present in adult humans, are more frequent in women than in men, and may be quantified noninvasively with the use of (18)F-FDG PET-CT. Most important, the amount of brown adipose tissue is inversely correlated with body-mass index, especially in older people, suggesting a potential role of brown adipose tissue in adult human metabolism.

Dataset Information

Impact of age on the relationships of brown adipose tissue with sex and adiposity in humans.

Objective

Research design and methods

Results

Conclusions

Publications

Impact of age on the relationships of brown adipose tissue with sex and adiposity in humans.

Similar Datasets

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