Adipocytes IGFBP-2 expression in prepubertal obese children.
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.
Claudio
Maffeis
M
Regional Centre for Juvenile Diabetes, Section of Obesity and Clinical Nutrition, Department of Mother and Child, Biology-Genetics, University of Verona, Verona, Italy. claudio.maffeis@univr.it
Benjamim
Ficial
F
Riccardo
Bonadonna
B
Massimiliano
Corradi
C
Francesco
Bertoldo
B
Luciano
Cominacini
C
D017667:Adipocytes / Q000378:metabolism*; D002648:Child; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D020738:Leptin / Q000097:blood; D008297:Male; D009765:Obesity / Q000097:blood*; D050151:Subcutaneous Fat / Q000166:cytology / Q000378:metabolism*
D018971:Insulin-Like Growth Factor Binding Protein 2; D020738:Leptin; D007334:Insulin-Like Growth Factor I