Relationships between serum osteoprotegerin, matrix metalloproteinase-2 levels and bone metabolism in postmenopausal women

BACKGROUND: Serum osteoprotegerin (OPG) and matrix metalloproteinase-2 (MMP-2) have been shown to play a role in bone metabolism by degrading the bone matrix. The present study was undertaken to compare OPG and MMP-2 with bone mineral density and three markers (alkaline phosphatase (AKP), calcium and phosphorus) in postmenopausal women in Wuhan. METHODS: Serum OPG, MMP-2, and AKP of 78 Chinese postmenopausal women aged 48 to 65 were measured using enzyme-linked immunosorbent assay (ELISA). Bone mineral density was measured with dual energy X-ray absorptiometry (DEXA), and serum calcium and phosphorus were measured by auto biochemical analysis. RESULTS: Serum OPG and MMP-2 concentrations were significantly higher in postmenopausal women with osteoporosis ((127.6 +/- 6.3) ng/L; (1388 +/- 121) microg/L)) than those in age-matched normal controls ((72.3 +/- 2.4) ng/L; (1126 +/- 141) microg/L, P < 0.01). Negative relationships were found between serum OPG, MMP-2 levels and bone mineral density in osteoporotic women. Adjusted by age and body mass index (BMI), the correlation of MMP-2 with bone mineral density of the neck of the femur disappeared. In osteoporotic women, negative correlations between OPG, MMP-2 levels and serum calcium were found (r = -0.216; r = -0.269, P < 0.05), but positive correlations between OPG and serum AKP, serum phosphorus (r = 0.235; r = 0.124, P < 0.05). CONCLUSIONS: Significant correlations exist between serum OPG, MMP-2 levels and bone metabolism in high bone turnover of postmenopausal osteoporotic women. The concentrations of serum OPG and MMP-2 increase possibly as a concomitant event in the high bone turnover state, such as postmenopausal osteoporosis. Therefore serum OPG and MMP-2 could be used as indicators for the bone metabolism in postmenopausal osteoporotic women.