Increased plasma interleukin-1 receptor antagonist levels in men with visceral obesity

Background. Adipose tissue (AT) is an important source of interleukin-1 receptor antagonist (IL-1Ra). Its expression is markedly increased in obesity. Aims and methods. To quantify the associations of IL-1Ra with body fat distribution as well as to examine the respective contributions of IL-1Ra and visceral adiposity to the variation in some cardiometabolic risk (CMR) markers. Plasma IL-1Ra levels were measured in a sample of 117 healthy non-diabetic men (age: 44.9 +/- 10.1 years; body mass index (BMI): 28.8 +/- 4.5 kg/m(2)). Results. Plasma IL-1Ra levels correlated positively with BMI, waist girth, and visceral and subcutaneous AT (0.39 <= r<0.48; P<0.0001). Multiple regression analyses revealed that visceral AT was the best independent predictor of IL-1Ra levels, explaining 22% (P<0.0001) of its variance. IL-1Ra (P<0.05) was an independent predictor of several CMR markers including triglyceride and high-density lipoprotein (HDL) cholesterol levels, cholesterol/HDL cholesterol ratio, glucose and insulin concentrations in response to a 75 g oral glucose load, and fasting insulin levels, in addition to the expected contribution of visceral AT (P<0.05). Conclusions. These results suggest that elevated IL-1Ra concentrations are influenced to a greater extent by visceral than subcutaneous adiposity and that IL-1Ra is independently related to some features of CMR beyond the known contribution of visceral adiposity.