Relationships among serum receptor of nuclear factor-kappaB ligand, osteoprotegerin, high-sensitivity C-reactive protein, and bone mineral density in postmenopausal women: osteoimmunity versus osteoinflammatory.

Objective: The aim of this study was to investigate the correlations among circulating osteoprotegerin (OPG), the receptor activator of nuclear factor-JB ligand (RANKL), high-sensitivity C-reactive protein (hsCRP), and bone mineral density (BMD) in healthy postmenopausal women. Methods: In a population-based study, highly specific enzyme-linked immunosorbent assay methods were used to evaluate the sera of 382 healthy Iranian postmenopausal women (mean age T SD, 58.7 T 7.5 y) for RANKL, OPG, hsCRP, degradation products of C-terminal telopeptides of type I collagen, and osteocalcin. BMD was determined for the lumbar spine (L2-L4) and the proximal femur using dual-energy x-ray absorptiometry. Results: Circulating levels of OPG (r = 0.30, P G 0.001) and the RANKL/OPG ratio (r = j0.17, P G 0.001) were significantly associated with age. The geometric mean of hsCRP was 1.89 mg/L (SE, 1.05) in the population studied. There was a significant correlation between log(hsCRP) levels and body mass index (BMI; r = 0.36, P G 0.001). Multivariate linear analyses revealed that age (A = j0.295, P G 0.001), BMI (A = 0.464, P G 0.001), RANKL (A = j0.105, P = 0.014), and OPG (A = 0.098, P = 0.029) were the independent determinants for lumbar BMD (R2 = 0.35). Age (A = j0.250, P G 0.001), BMI (A = 0.486, P G 0.001), and RANKL (A = j0.110, P = 0.009) were independently correlated with femoral neck BMD (R2 = 0.36). Age- and BMI-adjusted analysis by quartiles of log-transformed hsCRP did not reveal an association with BMD, serum levels of biochemical markers of bone turnover, RANKL, or OPG. Conclusions: The circulating levels of the RANKL/OPG osteoimmunity system have an association with BMD, but subclinical systemic inflammation may not be involved in bone mass in healthy postmenopausal women. Key Words: Receptor activator of nuclear factor-JB ligand Y Osteoprotegerin Y C-reactive protein Y Inflammation Y Bone mineral density.

Receptor activator of nuclear factor-kB ligand Y Osteoprotegerin- C-reactive protein -Inflammation - Bone mineral density.