title: IGFBP-2 is a negative predictor of cold-induced brown fat and bone mineral density in young non-obese women.
abstract: Recent studies have shown a positive correlation between brown adipose tissue (BAT) and bone mineral density (BMD). However, mechanisms underlying this relationship are unknown. Insulin-like growth factor 1 (IGF-1) is an important regulator of stem cell differentiation promoting bone formation. IGF binding protein 2 (IGFBP-2) binds IGF-1 in the circulation and has been reported to inhibit bone formation in humans. IGF-1 is also a crucial regulator of brown adipocyte differentiation. We hypothesized that IGFBP-2 is a negative and IGF-1 a positive regulator of BAT-mediated osteoblastogenesis. We therefore investigated a cohort of 15 women (mean age 27.7±5.7years): 5 with anorexia nervosa (AN) in whom IGF-1 levels were low due to starvation, 5 recovered AN (AN-R), and 5 women of normal weight. All subjects underwent assessment of cold-activated BAT by PET/CT, BMD of the spine, hip, femoral neck, and total body by DXA, thigh muscle area by MRI, IGF-1 and IGFBP-2. There was a positive correlation between BAT and BMD and an inverse association between IGFBP-2 and both BAT and BMD. There was no association between IGF-1 and BAT. We show for the first time that IGFBP-2 is a negative predictor of cold-induced BAT and BMD in young non-obese women, suggesting that IGFBP-2 may serve as a regulator of BAT-mediated osteoblastogenesis.
authors.affiliation: Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA. mbredella@partners.org
authors.forename: Miriam A
authors.initials: MA
authors.lastname: Bredella
authors.forename: Pouneh K
authors.initials: PK
authors.lastname: Fazeli
authors.forename: Beata
authors.initials: B
authors.lastname: Lecka-Czernik
authors.forename: Clifford J
authors.initials: CJ
authors.lastname: Rosen
authors.forename: Anne
authors.initials: A
authors.lastname: Klibanski
mesh_terms: D015502:Absorptiometry, Photon; D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000328:Adult; D015519:Bone Density / Q000502:physiology*; D003080:Cold Temperature; D005260:Female; D006801:Humans; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D049268:Positron-Emission Tomography; D055815:Young Adult
chemical_list: D018971:Insulin-Like Growth Factor Binding Protein 2; D007334:Insulin-Like Growth Factor I