Adipocytes IGFBP‐2 Expression in Prepubertal Obese Children

Abstract

Aims of the study were to measure insulin-like growth factor-binding protein-2 (IGFBP-2) expression by abdominal subcutaneous adipocytes and to assess the relationship between IGFBP-2 expression, circulating IGFBP-2, obesity, and insulin sensitivity in obese children. Thirty-eight obese children were recruited. Insulin sensitivity was assessed by intravenous glucose tolerance test and body composition by total-body dual-energy X-ray absorptiometry. Serum free and total IGF-I, IGFBP-2, adiponectin, and leptin were measured. Relative quantification of IGFBP-2 mRNA by subcutaneous adipose tissue biopsies was obtained using real-time PCR. Circulating IGFBP-2 was positively associated with insulin sensitivity, in agreement with previous studies. IGFBP-2 expression was associated with fat mass percentage (r = 0.656; P < 0.02), insulin sensitivity (r = -0.604; P < 0.05), free IGF-I (r = 0.646; P < 0.05), and leptin (r = 0.603; P < 0.05), but not with circulating IGFBP-2 (r = 0.003, P = ns). The association between IGFBP-2 expression and adiposity (r = 0.648; P < 0.05) was independent of insulin sensitivity (covariate). In conclusion, circulating IGFBP-2 was positively associated with insulin sensitivity. IGFBP-2 was expressed by subcutaneous abdominal adipocytes of obese children and increased with adiposity, independently from the level of insulin sensitivity. IGFBP-2 expression may potentially be one of the local mechanisms used by adipocytes to limit further fat gain.