Inflammatory proteins are related to total and abdominal adiposity in a healthy adolescent population: the AVENA Study

BACKGROUND: In adults, obesity is characterized by a state of chronic low-grade inflammation accompanied by moderately high concentrations of acute phase inflammatory proteins. Recent results regarding C-reactive protein (CRP) point to a similar status in adolescents; however, studies of associations of the serum inflammatory proteins CRP, ceruloplasmin, and complement factors C3 and C4 with body fat distribution remain scarce. OBJECTIVE: We aimed to establish the possible relations of serum inflammatory proteins with body fat estimates and body fat distribution in an apparently healthy adolescent population. DESIGN: This report included 472 adolescents (248 males and 224 females) aged 13-18.5 y who were recruited from the Spanish cross-sectional multicenter AVENA Study for whom anthropometric and immunologic data were complete. The concentrations of the serum proteins and the in vitro production of cytokines (interleukin 6 and tumor necrosis factor α) by isolated and stimulated white blood cells were measured. Relations with anthropometric measurements were explored by using simple and partial correlations. RESULTS: CRP, C3, and C4 were correlated with central obesity (as measured by waist circumference) and total body fat in both sexes (P < 0.01) and with ceruloplasmin in females only. After further adjustment for BMI, C3 remained independently associated with central obesity (P < 0.05). Production of the cytokines by white blood cells did not seem to be affected by an excess of body fat. CONCLUSIONS: Total body fat seems to be associated with a chronic low-grade systemic inflammation in apparently healthy adolescents. Central obesity is independently associated with C3 concentrations, which makes this marker especially interesting for further studies of obesity-related diseases.