Weight loss in prepubertal obese children is associated with a decrease in adipocyte fatty-acid-binding protein without changes in lipocalin-2: a 2-year longitudinal study.

CONTEXT: Lipocalin-2 and adipocyte fatty-acid-binding protein (A-FABP or FABP4) are adipokines potentially involved in the pathophysiology of obesity and metabolic syndrome in adults. In children, they have been scarcely studied.
OBJECTIVE: To analyze lipocalin-2 and A-FABP circulating levels before and after 2 years of a dieting and lifestyle intervention in a prepubertal obese cohort. DESIGN AND
SETTING: Case-control study with a prospective follow-up of cases for 2 years in our referral pediatric endocrine outpatient center. PATIENTS AND METHODS: Seventy-three prepubertal obese children, 8.03 ± 1.08-years old, and 47 age- and gender-matched lean controls were studied. Anthropometric parameters, blood pressure, fasting oral glucose tolerance test, homeostatic model insulin resistance index (HOMA-IR), lipid profile, lipocalin-2, and A-FABP were evaluated. Weight loss was considered if z-score body mass index (BMI) decreased at least 0.5 s.d.
RESULTS: At baseline, lipocalin-2 and A-FABP were higher in prepubertal obese children than those in lean controls (P<0.001). A-FABP showed a gradual increase, according to the obesity degree (r(2)=0.632; P<0.001). After 2 years, obese patients who lost weight showed a decrease in A-FABP (a mean 2% reduction in BMI was associated with a mean 29% decrease in A-FABP (P<0.001)) without changes in lipocalin-2 levels. Regression model analysis adjusted by age, sex, BMI, and HOMA showed that A-FABP was lower in males (β=-5.77 (CI 95%: -9.7; -1.84)) and was modified by BMI (β=2.7 (CI 95%: 1.77-3.62), r(2)=0.659). Lipocalin-2 was not modified by any of these variables.
CONCLUSIONS: Prepubertal obese children show high plasma lipocalin-2 and A-FABP levels, but only A-FABP is influenced by weight loss.