Interleukin-6 regulates human adipose tissue lipid metabolism and leptin production in vitro.
Adipose tissue IL-6 expression is increased in obesity and is a strong predictor of abnormalities in adipocyte and systemic metabolism. We used adipose tissue organ culture to test the direct effects of IL-6 on leptin expression, lipolysis, and lipoprotein lipase activity. To assess possible interactions with the hormonal milieu, IL-6 effects were tested in the presence or absence of insulin and/or glucocorticoid [dexamethasone (dex)]. Because omental (Om) and abdominal sc depots differ in IL-6 expression, their responses to exogenous IL-6 were compared. Although IL-6 had no significant effects under basal conditions, culture with the combination of IL-6 and dex, compared with dex alone, for 2 d increased leptin in both depots [+95 +/- 30% (sc) and +67 +/- 19% (Om), P < 0.01]; IL-6 did not affect leptin production when added in the presence of insulin. Culture with IL-6 in the absence of hormones moderately increased lipolysis during culture in both sc and Om [+79 +/- 23% (sc) and +26 +/- 9% (Om), each P < 0.01]. IL-6 markedly reduced the high levels of lipoprotein lipase activity in tissue cultured with insulin plus dex. We conclude that high local concentrations of IL-6 can modulate leptin production and lipid metabolism in human adipose tissue.
Trujillo
Maria E
ME
Department of Nutritional Sciences, Rutgers University, New Brunswick, New Jersey 08901, USA.
Sullivan
Sean
S
Harten
Ingrid
I
Schneider
Stephen H
SH
Greenberg
Andrew S
AS
Fried
Susan K
SK
D000273:Adipose Tissue / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology*; D020738:Leptin / Q000096:biosynthesis* / Q000235:genetics; D050356:Lipid Metabolism; D008066:Lipolysis / Q000187:drug effects; D008071:Lipoprotein Lipase / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000032:analysis
D007328:Insulin; D015850:Interleukin-6; D020738:Leptin; D012333:RNA, Messenger; D003907:Dexamethasone; D008071:Lipoprotein Lipase