Background and aims: Fat and bone are linked by a multitude of pathways supporting a skeleton appropriate for the mass of adipose tissue of the organism. We aimed to investigate the relations of adipose tissue hormones such as leptin, adiponectin, retinol-binding-protein-4 (RBP-4) and lipocalin-2 along with the low grade inflammation marker hs-CRP with markers of bone metabolism such as osteoprotegerin (OPG), receptor-activator of NF-κB ligand (RANKL), osteocalcin, C-terminal-cross-linking-telopeptide of collagen type-I (CTX), bone-alkaline-phosphatase (bALP) and tartrate-resistant-acid-phosphatase-isoform-5b (bone TRACP-5b) in girls with various degrees of BMI.
Method: Eighty girls (aged 915 years) were enrolled in the study divided by their BMI-SDSs into four groups of 20 girls each: overweight 1.8±0.4; obese 2.2±0.4; morbidly obese 3.6±0.4 and lean controls −0.11±0.4, in whom adipocytokines, hs-CRP and bone markers were measured by means of immunoenzymatic techniques.
Results: We found that: i) OPG, RANKL and bALP levels decreased significantly as BMI-SDSs increased (P=0.03, P=0.03 and P<0.01 respectively), while osteocalcin, CTX and bone TRACP5 show no relations (P>0.60); ii) leptin correlated negatively with bALP, bone TRACP-5b, osteocalcin, OPG and RANKL (P<0.05, P=0.02 and P=0.006 respectively); adiponectin correlated positively with CTX and OPG (P=0.004 and P=0.04 respectively); RBP-4 correlated positively with OPG and bALP (P<0.01 and P=0.002 respectively), while NGAL correlated positively with bALP (P<0.001); iii) obesity-related systemic inflammation expressed as hs-CRP correlated positively only with OPG.
Conclusion: Our findings suggest that there are important links between adipose tissue-derived proteins and bone remodeling factors. Bone turnover was altered in obese girls mainly due to decreased OPG levels. There were significant correlations of OPG with leptin, adiponectin and hs-CRP, indicating that, probably, the bone mass is regulated by adipokines, as well as by low grade inflammation in obese children.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology