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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #116588
Title: PARACRINE AND ENDOCRINE ROLES FOR ADIPOSE TISSUE INTERLEUKIN-6

Author
item GREENBERG, ANDREW - HNRCA

Submitted to: North American Association for the Study of Obesity
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2000
Publication Date: 10/1/2000
Citation: GREENBERG, A.S. PARACRINE AND ENDOCRINE ROLES FOR ADIPOSE TISSUE INTERLEUKIN-6. NORTH AMERICAN ASSOCIATION FOR THE STUDY OF OBESITY. 2000.

Interpretive Summary:

Technical Abstract: Interleukin-6 (IL6) is a multifunctional cytokine produced by many different types of cells. We and others observed that serum levels of IL6 are proportional to BMI. We also found that IL6 release from subcutaneous adipose tissue fragments incubated in vitro is proportional to BMI and fat cell size, suggesting that adipose tissue may contribute to the increased serum IL6 in obesity. In vivo studies in humans have also demonstrated an increased release of IL6 from subcutaneous adipose tissue which was in proportion to BMI. These data suggest IL6, like TNF, acts as an adipostat. We find that IL6 decreases lipoprotein lipase activity and increases lepitin release (in the presence of glucocorticoids) in human adipose tissue. We found a direct correlation between fasting insulin levels and IL6, suggesting a possible role for this cytokine in modulating insulin sensitivity. To understand how adipose tissue IL6 expression is regulated, we studied human adipose tissue in organ culture. Long-term culture with insulin increased IL6 release and this effect may underlie the correlation between serum levels of these hormones. IL6 release was increased by TNF and decreased by glucocorticoid. IL6 release from omental adipose tissue was 2-3-fold higher than subcutaneous. Non-adipose stromal cells are the major source of adipose tissue IL6 in both depots. Adipose tissue secretes a significant amount of IL6 in a regualted manner and in proportion to obesity. IL6 is known to have potent metabolic and endocirne effects, including increased hepatic VLDL production, synthesis of acute phase proteins, and cortisol production. Increased adipose tissue production of IL6 in obesity may contribute to the metabolic complications associated with visceral obesity through multiple paracrine and endocrine mechanisms.