Sclerostin and Adipose Tissue

The role of sclerostin in lipid and glucose metabolism disorders

Lipid and glucose metabolism are critical for human activities, and their disorders can cause diabetes and obesity, two prevalent metabolic diseases. Studies suggest that the bone involved in lipid and glucose metabolism is emerging as an endocrine organ that regulates systemic metabolism through bone-derived molecules. Sclerostin, a protein mainly produced by osteocytes, has been therapeutically targeted by antibodies for treating osteoporosis owing to its ability to inhibit bone formation. Moreover, recent evidence indicates that sclerostin plays a role in lipid and glucose metabolism disorders. Although the effects of sclerostin on bone have been extensively examined and reviewed, its effects on systemic metabolism have not yet been well summarized. In this paper, we provide a systemic review of the effects of sclerostin on lipid and glucose metabolism based on in vitro and in vivo evidence, summarize the research progress on sclerostin, and prospect its potential manipulation for obesity and diabetes treatment.

Sclerostin and its association with insulin resistance in children and adolescents

INTRODUCTION

Recent studies have shown that sclerostin, which is mainly known as a negative regulator of bone formation, could play an important role in the crosstalk between bone and glucose metabolism. The aim of this study was to investigate the relationship between sclerostin, other bone and fat related factors as osteocalcin (OC), Receptor Activator of Nuclear Factor NF-қB ligand (RANKL), leptin and adiponectin with glucose metabolism and insulin action in children and adolescents with obesity compared with healthy children and adolescents.

METHODS

Fifty-five obese children and adolescents, a mean age of 13.2 ± 3.4 yrs., BMI 28.89 ± 5.5 kg/m², and 26 healthy controls (mean age 13.0 ± 4.3 yrs., BMI 19.96 ± 3.1 kg/m²), sex-, and Tanner stage-matched were included into the study. Fasting blood samples for measurement of sclerostin, glucose, lipid profile, HbA1c, C-peptide, OC, RANKL, leptin and adiponectin, and vitamin D were taken at 8.00 AM.

RESULTS

Sclerostin, osteocalcin, RANKL, and adiponectin levels did not differ between obese patients and the control group. Leptin and fasting insulin levels were significantly higher in obese subjects compared with controls (p < 0.01, p = 0.01, respectively). A positive correlation between sclerostin and OC (r = 0.417, p = 0.027) and negative correlations between sclerostin and HOMA-IR and between sclerostin and age (r = -0.24, p = 0.045, r = -0.23, p = 0.037, respectively) were found in all of the subjects. Sclerostin did not correlate with HbA1c, lipids, RANKL and fat-derived leptin and adiponectin. Partial correlation analysis adjusted for age, SDS-BMI and Tanner staging only revealed a negative correlation between sclerostin and HOMA-IR (r = -0.3, p = 0.01). In obese patients this correlation was stronger than in the whole group (r = -0.39, p = 0.005). Moreover, a negative correlation between sclerostin and insulin was found in obese patients (r = -0.39, p = 0.006). In the healthy cohort, sclerostin had a negative correlation only with C-peptide (r = -0.79, p = 0.02).

CONCLUSIONS

Sclerostin could play an important role in the regulation of glucose metabolism in children and adolescents, regardless of other fat and bone-derived factors. In obese young patients it's action could be associated with decreasing insulin resistance.