title: Adipose tissue interleukin-18 mRNA and plasma interleukin-18: effect of obesity and exercise.
abstract: OBJECTIVE
  Obesity and a physically inactive lifestyle are associated with increased risk of developing insulin resistance. The hypothesis that obesity is associated with increased adipose tissue (AT) interleukin (IL)-18 mRNA expression and that AT IL-18 mRNA expression is related to insulin resistance was tested. Furthermore, we speculated that acute exercise and exercise training would regulate AT IL-18 mRNA expression.
  
  
  METHODS
  Non-obese subjects with BMI < 30 kg/m(2) (women: n = 18; men; n = 11) and obese subjects with BMI >30 kg/m(2) (women: n = 6; men: n = 7) participated in the study. Blood samples and abdominal subcutaneous AT biopsies were obtained at rest, immediately after an acute exercise bout, and at 2 hours or 10 hours of recovery. After 8 weeks of exercise training of the obese group, sampling was repeated 48 hours after the last training session.
  
  
  RESULTS
  AT IL-18 mRNA content and plasma IL-18 concentration were higher (p < 0.05) in the obese group than in the non-obese group. AT IL-18 mRNA content and plasma IL-18 concentration was positively correlated (p < 0.05) with insulin resistance. While acute exercise did not affect IL-18 mRNA expression at the studied time-points, exercise training reduced AT IL-18 mRNA content by 20% in both sexes.
  
  
  CONCLUSIONS
  Because obesity and insulin resistance were associated with elevated AT IL-18 mRNA and plasma IL-18 levels, the training-induced lowering of AT IL-18 mRNA content may contribute to the beneficial effects of regular physical activity with improved insulin sensitivity.
authors.affiliation: Centre of Inflammation and Metabolism, Department of Molecular Biology, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark. LLeick@aki.ku.dk
authors.forename: Lotte
authors.initials: L
authors.lastname: Leick
authors.forename: Birgitte
authors.initials: B
authors.lastname: Lindegaard
authors.forename: Dorthe
authors.initials: D
authors.lastname: Stensvold
authors.forename: Peter
authors.initials: P
authors.lastname: Plomgaard
authors.forename: Bengt
authors.initials: B
authors.lastname: Saltin
authors.forename: Henriette
authors.initials: H
authors.lastname: Pilegaard
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D015992:Body Mass Index; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D020382:Interleukin-18 / Q000097:blood* / Q000235:genetics* / Q000378:metabolism; D008297:Male; D009765:Obesity / Q000097:blood* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D020382:Interleukin-18; D012333:RNA, Messenger