Interleukin-18 in plasma and adipose tissue: effects of obesity, insulin resistance, and weight loss
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OBJECTIVE: Interleukin (IL)-18 is associated with obesity, insulin resistance, and cardiovascular disease. The present study compared 1) IL-18 in adipocytes versus stromal vascular (SV) cells, 2) IL-18 in plasma and adipose tissue (AT) in obese versus lean subjects, and 3) IL-18 in plasma, AT, and skeletal muscle (SM) in obese subjects after weight loss. SUBJECTS AND METHODS: At baseline, plasma and AT IL-18 in 23 obese subjects were compared with that in 12 lean subjects. The obese subjects were submitted to a 15-week life-style intervention (hypocaloric diet and daily exercise) after which plasma samples, AT, and SM biopsies were obtained. Analyses were performed by ELISA and RT-PCR respectively. RESULTS: IL-18 expression in isolated adipocytes was approximately 2% of that in SV cells. Plasma IL-18 was higher in obese subjects (P < 0.001) and associated with insulin resistance (HOMA; P < 0.001). AT expression of IL-18, CD14, and CD68 was higher in obese (P < 0.01). The intervention reduced body weight (P < 0.001), plasma IL-18 (P < 0.001), and increased insulin sensitivity (HOMA; P < 0.05). AT and SM expression of IL-18 remained unchanged after the intervention. Changes in plasma IL-18 were associated with changes in insulin sensitivity (P < 0.05) but not with BMI or AT expression of IL-18. CONCLUSION: Plasma IL-18 is associated with changes in insulin resistance and reduced after weight loss. AT expression of IL-18 is increased in obesity but not affected by weight loss, indicating that changes in plasma IL-18 are related to insulin resistance rather than changes in obesity per se.
Original language | English |
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Journal | European Journal of Endocrinology |
Volume | 157 |
Issue number | 4 |
Pages (from-to) | 465-71 |
Number of pages | 6 |
ISSN | 0804-4643 |
DOIs | |
Publication status | Published - 2007 |
Bibliographical note
Keywords: Adipocytes; Adipose Tissue; Adult; Cells, Cultured; Cross-Sectional Studies; Diet Therapy; Exercise Therapy; Female; Humans; Inflammation Mediators; Insulin Resistance; Interleukin-18; Male; Obesity; Stromal Cells; Thinness; Weight Loss
ID: 20293826