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-kappaB 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 +/- SD, 58.7 +/- 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 < 0.001) and the RANKL/OPG ratio (r = -0.17, P < 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 < 0.001). Multivariate linear analyses revealed that age (beta = -0.295, P < 0.001), BMI (beta = 0.464, P < 0.001), RANKL (beta = -0.105, P = 0.014), and OPG (beta = 0.098, P = 0.029) were the independent determinants for lumbar BMD (R(2) = 0.35). Age (beta = -0.250, P < 0.001), BMI (beta = 0.486, P < 0.001), and RANKL (beta = -0.110, P = 0.009) were independently correlated with femoral neck BMD (R(2) = 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.
Nabipour
Iraj
I
Department of Endocrine and Metabolic Diseases, The Persian Gulf Tropical Medicine Research Center, Bushehr University of Medical Sciences, Bushehr, Islamic Republic of Iran. inabipour@gmail.com
Larijani
Bagher
B
Vahdat
Katayoun
K
Assadi
Majid
M
Jafari
Seyed Mojtaba
SM
Ahmadi
Esmaeil
E
Movahed
Ali
A
Moradhaseli
Farzad
F
Sanjdideh
Zahra
Z
Obeidi
Narges
N
Amiri
Zahra
Z
D015502:Absorptiometry, Photon; D000367:Age Factors; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology*; D002097:C-Reactive Protein / Q000276:immunology / Q000378:metabolism*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007249:Inflammation; D007492:Iran / Q000453:epidemiology; D016014:Linear Models; D008875:Middle Aged; D015999:Multivariate Analysis; D015663:Osteoporosis, Postmenopausal / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology; D053244:Osteoprotegerin / Q000097:blood* / Q000276:immunology; D017698:Postmenopause / Q000502:physiology*; D011237:Predictive Value of Tests; D053245:RANK Ligand / Q000097:blood* / Q000276:immunology
D015415:Biomarkers; D053244:Osteoprotegerin; D053245:RANK Ligand; D002097:C-Reactive Protein