TY - JOUR

T1 - Interleukin-18 in plasma and adipose tissue: effects of obesity, insulin resistance, and weight loss

AU - Bruun, Jens M

AU - Stallknecht, Bente

AU - Helge, Jørn W

AU - Richelsen, Bjørn

N1 - 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

PY - 2007

Y1 - 2007

N2 - 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.

AB - 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.

U2 - 10.1530/EJE-07-0206

DO - 10.1530/EJE-07-0206

M3 - Journal article

C2 - 17893261

VL - 157

SP - 465

EP - 471

JO - European Journal of Endocrinology

JF - European Journal of Endocrinology

SN - 0804-4643

IS - 4

ER -