Correlations between serum concentration of three bone-derived factors and obesity and visceral fat accumulation in a cohort of middle aged men and women.
BACKGROUND
The aim of this study was to investigate the interrelationships between three bone-derived factors [serum osteocalcin (OCN), fibroblast growth factor (FGF) 23, and neutrophil gelatinase-associated lipocalin (NGAL) levels] and body fat content and distribution, in order to reveal the potential endocrine function of bone in the development of obesity.


METHODS
We recruited 1179 people (aged 59.5 ± 6.2 years) from communities in Shanghai. Serum OCN levels were determined using an electrochemiluminescence immunoassay. Serum FGF23 and NGAL levels were determined using a sandwich enzyme-linked immunosorbent assay. The abdominal fat distribution, including visceral fat area (VFA), was assessed by magnetic resonance imaging. Visceral obesity was defined as a VFA ≥ 80 cm2.


RESULTS
Serum OCN levels were inversely correlated with body fat parameters, while FGF23 and NGAL were positively correlated (P < 0.05). After adjusting for confounders, waist circumference (W) and VFA had a closer relationship with serum OCN, FGF23, and NGAL levels than body mass index (BMI) and body fat percentage (fat%, all P < 0.05). The risk of visceral obesity significantly increased with higher FGF23 and/or NGAL levels, as well as with reduced OCN levels (all P < 0.05). In addition, serum OCN, FGF23, and NGAL levels were independently associated with visceral obesity (all P < 0.01). The relationships persisted among subjects with normal glucose tolerance or subjects with hyperglycaemia (both P < 0.05).


CONCLUSIONS
Compared to the indicators of overall adiposity such as BMI or fat%, visceral adiposity indicators (W or VFA) were more closely related to serum OCN, FGF23 and NGAL levels. There was no interaction among the relationship of three bone-derived factors with visceral obesity, which revealed the independent relationship of endocrine function of skeleton with body fat.
['Xu|Yiting|Y|', 'Ma|Xiaojing|X|', 'Pan|Xiaoping|X|', 'He|Xingxing|X|', 'Xiao|Yunfeng|Y|', 'Bao|Yuqian|Y|0000-0002-4754-3470']
D050154:Adiposity D000328:Adult D000368:Aged D015415:Biomarkers D015992:Body Mass Index D001842:Bone and Bones D002681:China D004797:Enzyme-Linked Immunosorbent Assay D005260:Female D000089703:Fibroblast Growth Factor-23 D005346:Fibroblast Growth Factors D006801:Humans D050152:Intra-Abdominal Fat D000071068:Lipocalin-2 D008279:Magnetic Resonance Imaging D008297:Male D008875:Middle Aged D009765:Obesity D015675:Osteocalcin D050507:Subcutaneous Fat, Abdominal D055105:Waist Circumference
Osteocalcin Neutrophil gelatinase-associated lipocalin Fat distribution Visceral fat area Fibroblast growth factor 23 Lipocalin-2