Context: Retinol binding protein (RBP4), secreted primarily from the liver and adipose tissues, was recently proposed as a link between obesity and insulin resistance. The role of RBP4 in pediatric obesity, its relationship with subclinical inflammation, and its response to lifestyle changes are not elucidated. Objective: The objective of the study was to determine in children: 1) the status of RBP4 levels in lean vs. obese; 2) the relationship between RBP4 levels and subclinical inflammation; and 3) the effect of lifestyle-only intervention on RBP4 levels. Design, Setting, and Patients: Lean and obese children (n = 21) matched for age (>14 yr to < 18 yr) and maturity stage (Tanner IV) were studied at baseline and with lifestyle intervention in obese subjects only (n = 15). Intervention: Patients received 3 months of randomized and controlled physical activity-based lifestyle intervention. Main Outcome Measure: RBP4 levels in children before and after intervention and the relationship between RBP4 and subclinical inflammation were measured. Results: Higher RBP4 levels were found in the obese group vs. lean group (P = 0.005). RBP4 correlated with not only indices of obesity and insulin resistance but also inflammatory factors (r = 0.63 and 0.64 for C-reactive protein and IL-6, respectively, P < 0.01). Intervention reduced RBP4 levels by approximately 30% (P = 0.001), and RBP4 reduction was correlated with the magnitude of decrease in inflammatory factors (P = 0.01). Conclusion: Alterations in serum RBP4 occur at an early age in the clinical course of obesity and appear to correlate with subclinical inflammation. Lifestyle intervention almost entirely reversed the raised RBP4 levels in obese children. Future studies should determine whether elevation of RBP4 is a direct trigger for the insulin resistance and subclinical inflammation implicated in the premature development of cardiovascular disease and diabetes.

Hypoadiponectinemia and chronic subclinical inflammation in adults are associated with the development of diabetes and cardiovascular disease. The potential relationship between adiponectin and inflammation and its modulation by lifestyle intervention in the pediatric obese population remain unclear. The objectives were to investigate in adolescents 1) the relationship between adiponectin and obesity-related inflammatory factors, C-reactive protein, and IL-6; and 2) the effect of a lifestyle intervention on adiponectin and whether these effects are related to changes in inflammatory factors. Twenty-one obese and age-matched lean adolescents (age, 14-18 yr; Tanner stage, > or =IV) were studied cross-sectionally. Fifteen obese adolescents also underwent a randomized, controlled physical activity-behavior-diet-based lifestyle intervention for 3 months. Associations among adiponectin, fat mass, insulin resistance, and inflammatory factors at baseline as well as after the intervention were assessed. Plasma adiponectin concentration was lower (P < 0.001) in the obese vs. age-matched lean adolescents. Significant inverse relationships were observed between adiponectin and inflammatory factors, insulinemia, insulin resistance, and fat mass. Intervention produced a 34% increase in adiponectin concentration (P = 0.0004) despite negligible weight loss but with reductions in fat mass, hyperinsulinemia, insulin resistance, and inflammatory factors (all P < 0.01). The data suggest that in adolescents, obesity-related hypoadiponectinemia is associated with subclinical inflammation, and a short-term lifestyle intervention augments adiponectin concentrations. These effects appear to be related to reductions in fat mass and inflammatory factors. Based on our current understanding of adiponectin physiology, reversal of hypoadiponectinemia in obese adolescents may protect against risks for cardiovascular disease and diabetes.

Context: Elevated concentrations of branched-chain amino acids (BCAA) are strong predictors of type 2 diabetes mellitus (T2DM). Their association with cardiovascular disease (CVD) remains uncertain, particularly in youth. Objective: We investigated the role of BCAA and aromatic amino acids (AAA) in obesity, their relationships with novel biomarkers of CVD, and response to a physical activity-based lifestyle intervention (PAL-I) in a randomized controlled study in youth with normal weight (NW) and obesity (OB). Methods: Age (14-18 years) and Tanner stage (≥IV) matched youth (OB, n = 15 and NW, n = 6) were studied; the 15 participants with OB underwent a 3-month randomized controlled PAL-I. Circulating amino acid profile, glucose, insulin, lipids, adiponectin, retinol binding protein-4, fibrinogen, high-sensitivity C-reactive protein, interleukin-6, and 25-hydroxy vitamin-D, along with body composition, were measured at baseline and after PAL-I. Independent t tests, analysis of covariance, and mixed-effect models were used for analysis of the data. Results: Compared with NW, the concentration of various amino acids, including BCAA and AAA, were altered in OB (P < 0.05). BCAA and AAA showed baseline correlations with body composition and novel biomarkers of CVD, particularly inflammatory factors (all P < 0.05). The PAL-I produced only negligible effects (P > 0.05) on BCAA and AAA. Glutamine, glycine, and aspartic acid decreased with PAL-I (all P < 0.05). Conclusion: The novel finding of the BCAA–inflammation relationship, along with strong correlations with nontraditional biomarkers of CVD, may raise the prospect of BCAA as a biomarker of CVD and evoke a potential link between obesity, T2DM, and CVD.