Adipocytokine profile and insulin resistance in childhood obesity

Adipose tissue is a veritable "endocrine organ" due to its adipocytokines secretion implied in insulin sensitivity modulation and cardiovascular complications.

To identify the adipocytokines' plasmatic profile (adiponectin, leptin, resistin, IL-6, TNFα) in obese children and adolescents and to assess their relationship with "classic" clinical/paraclinical markers of metabolic syndrome and insulin resistance.

A case-control study comparing a study group of 38 obese children and adolescents (age 13.5±2.3 years) to a normal weight age matched control group of 24 children.We measured body mass index (BMI) and waist circumference (WC), systolic and diastolic blood pressure (BP). The classical metabolic parameters (fasting glycemia, total cholesterol and its fractions, serum triglycerides) were measured in both groups. Insulin sensitivity was evaluated using fasting insulinemia, HOMA-index and insulin-resistance summary score (IRS). Adiponectin, leptin, resistin, IL-6 and TNFα were measured using ELISA method.

Serum levels of leptin, resistin and IL-6 were signficantly higher (42.42±22.58 ng/ml versus 14.4±14.49 ng/ml, p <0.001; 9.69±3.47 ng/ml versus 7.92±2.13ng/ml, p = 0.029 and 2.66 ±2.87 pg/ml versus 0.89 ± 1.16 pg/ml, p = 0.006 respectively), while adiponectin levels were significantly lower (9.05±4.61 µg/ml versus 15.93±9.24 μg/ml, p <0.001) in the obese group compared to control group. TNFα was not statistical different between groups.In multivariate regression analysis adiponectin was negatively and significantly correlated with WC (r = - 0.463, p = 0.003); leptin was positively and significantly related to WC, diastolic BP, fasting insulinemia and resistin (r = 0.775, p <0.001); resistin was positively related to leptin and IL-6 (r = 0.499, p <0.001), IL-6 was positively and significantly related to diastolic blood pressure (r = 0.333, p = 0.008).

Serum levels of adiponectin, leptin, resistin and IL-6 are significantly different in obese children compared to normal weight controls; leptin was the only adipokine correlated with insulin resistance in children. There are significant correlations between plasmatic levels of leptin, resistin and IL-6.Simple plasmatic determination of TNFα is not a marker of the degree of obesity or its metabolic complications in pediatric population.