Bone Abstracts

Intermittent PTH reduces vertebral fractures risk in osteoporotic patients. The mechanisms trough which PTH acts are not completely understood, it has been observed to activate Wnt pathways in osteoblasts (OBs). Activation of this pathway induces OB proliferation, differentiation and prevents apoptosis. Recently increased expression of Wnt10b by T cells during intermittent PTH, and no increase during continuous PTH has been demonstrated in mice.In order to evaluate if PTH increases Wnt10b expression lymphoid humans cells, we measured this molecule at baseline and during treatment in osteoporotic women and in patients with primary hyperparatiroidism before and after surgery.

Forty postmenopausal osteoporotic women were randomly assigned to therapy with: 1–84 PTH 100 μg plus calcium 1200 mg and vitamin D 800 IU daily, or with calcium and vitamin D alone and return for control visit and exams at 3, 6, 12 and 18 months of treatment.

Twenty patients affected by primary hyperparathyroidism and subjected to surgical parathyroidectomy were enrolled and evaluated at baseline and 1 month after surgery.

Real time PCR for WNT10b was performed on peripheral blood lymphoid cells, osteocalcin and bone alkaline phosphatase were measured by ELISA.

Our data show an increase in WNT10b expression by lymphoid cells that was maximum (more than 20-fold) after 6 months of treatment, after 18 months WNT10b returned to basal expression. The WNT10b curve acts similarly to the bone formation markers curve. In patients treated with calcium and vitamin D alone no increase in WNT10b was observed. Also in patients affected by hyperparathyroidism there was no difference in WNT10b before and after surgery.

Our data suggest an effect of intermittent, but not continuous PTH on the expression of WNT10b by lymphoid cells, this could be one of the mechanisms trough which PTH treatment increases OB formation and function in humans.