Circulating Levels of Persistent Organic Pollutants in Relation to Visceral and Subcutaneous Adipose Tissue by Abdominal MRI

Obesity is associated with elevated inflammatory signals from various adipose tissue depots. This study aimed to evaluate release of regulated on activation, normal T cell expressed and secreted (RANTES) by human adipose tissue in vivo and ex vivo, in reference to monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) release. Arteriovenous differences of RANTES, MCP-1, and IL-6 were studied in vivo across the abdominal subcutaneous adipose tissue in healthy Caucasian subjects with a wide range of adiposity. Systemic levels and ex vivo RANTES release were studied in abdominal subcutaneous, gastric fat pad, and omental adipose tissue from morbidly obese bariatric surgery patients and in thoracic subcutaneous and epicardial adipose tissue from cardiac surgery patients without coronary artery disease. Arteriovenous studies confirmed in vivo RANTES and IL-6 release in adipose tissue of lean and obese subjects and release of MCP-1 in obesity. However, in vivo release of MCP-1 and RANTES, but not IL-6, was lower than circulating levels. Ex vivo release of RANTES was greater from the gastric fat pad compared with omental ( P = 0.01) and subcutaneous ( P = 0.001) tissue. Epicardial adipose tissue released less RANTES than thoracic subcutaneous adipose tissue in lean ( P = 0.04) but not obese subjects. Indexes of obesity correlated with epicardial RANTES but not with systemic RANTES or its release from other depots. In conclusion, RANTES is released by human subcutaneous adipose tissue in vivo and in varying amounts by other depots ex vivo. While it appears unlikely that the adipose organ contributes significantly to circulating levels, local implications of this chemokine deserve further investigation.

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Effects of a physiological GH pulse on interstitial glycerol in abdominal and femoral adipose tissue

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1999.277.5.e848 ◽

1999 ◽

Vol 277 (5) ◽

pp. E848-E854 ◽

Cited By ~ 10

Author(s):

Claus Højbjerg Gravholt ◽

Ole Schmitz ◽

Lene Simonsen ◽

Jens Bülow ◽

Jens Sandahl Christiansen ◽

...

Keyword(s):

Adipose Tissue ◽

Subcutaneous Adipose Tissue ◽

Regional Differences ◽

Subcutaneous Fat ◽

Tissue Blood Flow ◽

Abdominal Adipose Tissue ◽

Adipose Tissue Blood Flow ◽

Subcutaneous Adipose ◽

Circulating Levels ◽

Stimulation Of

Physiologically, growth hormone (GH) is secreted in pulses with episodic bursts shortly after the onset of sleep and postprandially. Such pulses increase circulating levels of free fatty acid and glycerol. We tested whether small GH pulses have detectable effects on intercellular glycerol concentrations in adipose tissue, and whether there would be regional differences between femoral and abdominal subcutaneous fat, by employing microdialysis for 6 h after administration of GH (200 μg) or saline intravenously. Subcutaneous adipose tissue blood flow (ATBF) was measured by the local Xenon washout method. Baseline of interstitial glycerol was higher in adipose tissue than in blood [220 ± 12 (abdominal) vs. 38 ± 2 (blood) μmol/l, P < 0.0005; 149 ± 9 (femoral) vs. 38 ± 2 (blood) μmol/l, P < 0.0005] and higher in abdominal adipose tissue compared with femoral adipose tissue ( P < 0.0005). Administration of GH induced an increase in interstitial glycerol in both abdominal and femoral adipose tissue (ANOVA: abdominal, P = 0.04; femoral, P = 0.03). There was no overall difference in the response to GH in the two regions during the study period as a whole (ANOVA: P = 0.5), but during peak stimulation of lipolysis abdominal adipose tissue was, in absolute but not in relative terms, stimulated more markedly than femoral adipose tissue (ANOVA: P = 0.03 from 45 to 225 min). Peak interstitial glycerol values of 253 ± 37 and 336 ± 74 μmol/l were seen after 135 and 165 min in femoral and abdominal adipose tissue, respectively. ATBF was not statistically different in the two situations (ANOVA: P = 0.7). In conclusion, we have shown that a physiological pulse of GH increases interstitial glycerol concentrations in both femoral and abdominal adipose tissue, indicating activated lipolysis. The peak glycerol increments after GH were higher in abdominal adipose tissue, perhaps due to a higher basal rate of lipolysis in this region.

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Higher production of IL-8 in visceral vs. subcutaneous adipose tissue. Implication of nonadipose cells in adipose tissue

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00269.2003 ◽

2004 ◽

Vol 286 (1) ◽

pp. E8-E13 ◽

Cited By ~ 127

Author(s):

Jens M. Bruun ◽

Aina S. Lihn ◽

Atul K. Madan ◽

Steen B. Pedersen ◽

Kirsten M. Schiøtt ◽

...

Keyword(s):

Adipose Tissue ◽

Subcutaneous Adipose Tissue ◽

Human Adipose Tissue ◽

Resistance Development ◽

Paired Samples ◽

Obese Subjects ◽

Isolated Adipocytes ◽

Subcutaneous Adipose ◽

Circulating Levels

IL-8 is released from human adipose tissue. Circulating IL-8 is increased in obese compared with lean subjects and is associated with measures of insulin resistance, development of atherosclerosis, and cardiovascular disease. We studied 1) the production and release of IL-8 in vitro from paired samples of subcutaneous (SAT) and visceral (VAT) adipose tissue and 2) the production of IL-8 from whole adipose tissue, isolated adipocytes, and nonfat cells of adipose tissue. IL-8 release from VAT was fourfold higher than from SAT ( P < 0.05), and IL-8 mRNA was twofold higher in VAT compared with SAT ( P < 0.01). Dexamethasone (50 nM) attenuated IL-8 production by 50% ( P < 0.05), and IL-1β (2 μg/l) increased IL-8 production up to 15-fold ( P < 0.001). IL-8 release from whole SAT explants correlated with body mass index (BMI; r = 0.78; P < 0.001), as did IL-8 release from nonfat cells ( r = 0.79; P < 0.001). However, no correlation was found between IL-8 release from the fraction of isolated adipocytes and BMI ( r = 0.01). In conclusion, we demonstrated an increased release of IL-8 from VAT compared with SAT. Furthermore, our data suggest that the observed elevation in circulating levels of IL-8 in obese subjects is due primarily to the release of IL-8 from nonfat cells from adipose tissue. The high levels of IL-8 release from human adipose tissue and accumulation of this tissue in obese subjects may account for some of the increase in circulating IL-8 observed in obesity.

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