Changes In Serum Cbfa1 And MMP-13 In Women With Established Osteoporosis Treated With RhPTH(1-34)

Objective: To investigate the changes of serum Cbfa1 and MMP-13 levels in women with established postmenopausal osteoporosis treated with rhPTH(1-34), and the relationship between serum Cbfa1, MMP-13 and serum BSAP , bone mineral density (BMD), body mass index (BMI), serum calcium, serum phosphate levels as well as other factors.Methods: Forty-five postmenopausal women with established osteoporosis (mean age 62±7 years) received daily subcutaneous injections of 20μg rhPTH(1-34) plus oral 600 mg elemental calcium and 125 IU vitamin D3 for 6 months. Serum Cbfa1, MMP-13 and BSAP levels were measured by enzyme linked immunosorbent assay before and after six-month treatment. BMD at four sites were measured by DEXA as well. The relationship between serum Cbfa1, MMP-13 and serum BSAP, Ca, P, BMD, BMI were also analyzed by bivariate correlation and multivariate regression.Results: After the treatment with PTH, compared with baseline, lumbar spine BMD increased significantly after PTH(1-34) treatment (4%, p<0.01). The BMD at the femoral neck, trochanter, Ward's triangle showed no significant change throughout the study period. Serum calcium and phosphate were elevated significantly (both p<0.01),serum BSAP was also significantly increased (p<0.05). On the contrary, serum Cbfa1 and MMP-13 levels were markedly decreased by 13.1% and 36.6% respectively (p<0.05 and p<0.01). The bivariate correlation and multivariate regression showed that, in the baseline, serum Cbfa1 correlated positively with MMP-13(r=0.739, p< 0.01).serum BSAP correlated negatively with Cbfa1 and MMP-13 (r=-0.498, p<0.01 and r=-0.738, p<0.01). BMD at lumber spine correlated positively with BMI ( r=0.336, p<0.05), negatively with BSAP (r= -0.384, p< 0.01). Multiple regression analysis showed that BMI was the independent related factor influencing BMD at L2-4. After the therapy of 6 months, serum Cbfa1 still correlated positively with MMP-13(r=0.496,p<0.01).BSAP still correlated negatively with MMP-13 and Cbfa1 (r=-0.584, p< 0.01 and r= -0.405, p< 0.01). BMD at L2-4 remained correlated positively with BMI(r=0.339, p<0.05). BMI was still the independentrelated factor influencing BMD at L2-4.Conclusion: Cbfa1 and MMP-13 play a important role in the process of postmenopausal osteoporosis-treatment by PTH, as well as in the process of normal bone metabolism. The excessive high level of Cbfa1 and MMP-13 may make against bone formation.