Receptor activator of NF(Kappa)B ligand/osteoprotegerin (RANKL/OPG) system and osteopontin (OPN) serum levels in a population of apulian postmenopausal women

Aim. Osteoporosis is a bone disease, characterized by a reduction of bone resistance; in postmenopausal period bone metabolism is imbalanced. Several parameters have been proposed as markers of bone metabolism; the attention have been recently placed on the receptor of activator of NF(Kappa)B ligand receptor (RANKL) and osteoprotegerin (OPG), namely RANKL/OPG system. The aim of this paper is to evaluate changes in postmenopausal women in serum concentration of OPG, RANKL, and their ratio (i.e. RANKL/OPG ratio), osteopontin (OPN), bone-type alcaline phosphatase (BAP), serum-NTelopeptide of type I collagen (serum-NTX); and their correlations with bone mineral density (BMD). Methods. An Apulian population group of 163 native postmenopausal women were followed at the Osteoporosis Centre of Policlinico of Bari (Southenrn Italy). Patients were classified into 3 separate groups, according to T-score: osteoporotic, osteopenic and control group. Serum concentrations of OPG, RANKL, RANKL/OPG ratio, BAP and NTX have been calculated. Results. No differences were found in OPG and BAP values. Significant correlations were found in the osteopenic group between OPG and RANKL (negative), and between RANKL and OPN or serum-NTX, OPN and serum-NTX or RANKL/OPG ratio, BAP and serum-NTX, serum-NTX and RANKL/OPG ratio (positive). In the other groups a significant correlation was observed between BAP and NTX. Conclusions. In postmenopausal women, important modifications of bone metabolism markers (i.e. RANKL, OPG and OPN) could be due to serious engagement of bone turnover, especially in the pre-osteoporotic phase. Low bone density in postmenopausal women should be identified as soon as possible, and urgent measures are needed to reverse the process. Parameters namely RANKL e OPG may become an important index for the evaluation of the activity of drugs against osteoporosis, old and new like AMG 162 (anti-RANKL action)