Expression of interleukin-6 is greater in preadipocytes than in adipocytes of 3T3-L1 cells and C57BL/6J and ob/ob mice.
Inflammation plays a major role in the development of chronic diseases such as cardiovascular disease and Type 2 diabetes. Further, it was demonstrated that obese animals and humans have significantly higher levels of circulating proinflammatory cytokines, such as interleukin-6 (IL-6). The aim of this study was to determine whether adipose tissue could be a major source of circulating IL-6 in leptin-deficient obese (ob/ob) mice by comparing the expression of IL-6 in different tissues of ob/ob mice. Our secondary goal was to determine whether preadipocytes are the source of adipose tissue IL-6. The ob/ob mice had higher levels of plasma IL-6 (P < 0.05) and adipose tissue IL-6 mRNA (P < 0.05) compared with lean mice. Interestingly, IL-6 mRNA levels of liver and spleen were not different between ob/ob and lean mice, whereas adipose tissue IL-6 mRNA levels were higher in the ob/ob mice compared with lean mice (P < 0.05). In addition, we showed that IL-6 secretion from the adipose tissue stromal vascular fraction cells was higher than that from fully differentiated adipocytes (P < 0.001). We further demonstrated that 3T3-L1 preadipocytes had significantly higher levels of lipopolysaccharide (LPS)-stimulated IL-6 mRNA and IL-6 secretion than differentiated 3T3-L1 adipocytes. Taken together, these data suggest that adipose tissue and preadipocytes from the adipose tissue stromal vascular fraction may contribute significantly to the increased plasma IL-6 levels in ob/ob mice.
Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
Janette M
JM
Harkins
Naima
N
Moustaid-Moussa
Yong-Joo
YJ
Chung
Kristen M
KM
Penner
James J
JJ
Pestka
Colin M
CM
North
Kate J
KJ
Claycombe
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose; D007249:Inflammation / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D015850:Interleukin-6 / Q000378:metabolism*; D020738:Leptin / Q000097:blood / Q000172:deficiency; D008070:Lipopolysaccharides; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D009765:Obesity / Q000378:metabolism*
D001786:Blood Glucose; D007328:Insulin; D015850:Interleukin-6; D020738:Leptin; D008070:Lipopolysaccharides