The bone mass benefits of antiresorbers in postmenopausal osteoporosis are limited by the rapid coupling of decreasing bone resorption with bone formation. Wnt signaling is involved in this coupling process during treatment with bisphosphonates, whereas its role during treatment with the anti-receptor activator of NF-κB ligand (RANKL) antibody denosumab is unknown. The study population includes patients participating in a placebo-controlled trial lasting 36 months: 19 women were on placebo and 24 on subcutaneous 60 mg denosumab every 6 months. All measured parameters (serum C-terminal telopeptide of type I collagen [sCTX], serum bone alkaline phosphatase [bAP], Dickkopf-1 [DKK1], and sclerostin) remained unchanged during the observation period in the placebo group. sCTX and bAP were significantly suppressed by denosumab treatment over the entire follow-up. Denosumab treatment was associated with significant (p < 0.05) increases (28% to 32%) in serum sclerostin over the entire study follow-up. Serum DKK1 significantly decreased within the first 6 months with a trend for further continuous decreases, which reached statistical significance (p < 0.05) versus placebo group from the 18th month onward. The changes in DKK1 were significantly and positively related with the changes in sCTX and bAP and negatively with hip bone mineral density (BMD) changes. The changes in sclerostin were significantly and negatively related only with those of bAP. The changes in bone turnover markers associated with denosumab treatment of postmenopausal osteoporosis is associated with significant increase in sclerostin similar to those seen after long-term treatment with bisphosphonates and significant decrease in DKK1. This latter observation might explain the continuous increase over 5 years in BMD observed during treatment of postmenopausal osteoporosis with denosumab.

Osteogenesis imperfecta (OI) is a hereditary disease characterized by low bone mass, increased bone fragility, short stature, and skeletal deformities. This study focuses on OI type I, the mildest form of the disease. Bisphosphonates represent the prevailing standard of care in patients with OI. Teriparatide (TPD) is a PTH analog with bone-anabolic actions which has been approved for osteoporosis treatment. Thirteen postmenopausal women with type I OI who had been on treatment with neridronate for at least 2 years and who incurred new vertebral fracture during treatment were treated with TPD for 18 months. Bone mineral density (BMD) increased significantly over 18 months up to 3.5 % at the lumbar spine (p = 0.001), while no significant changes were noted in hip BMD. Serum markers of bone formation and of bone resorption increased significantly during the treatment. The Wnt inhibitors serum dickkopf-1 (DKK1) and sclerostin were also measured. A nonsignificant increase was seen in serum sclerostin levels, while serum DKK1 rose gradually and significantly during TPD treatment. In patients affected by type I OI, TPD treatment is associated with a remarkable response in markers of bone formation. This suggests a normal osteoblastic response to TPD. However, the observed increases in BMD were somewhat lower than those in postmenopausal or senile osteoporosis treated with TPD for the same lag time. Our results open the possibility to develop TPD for the treatment of adult type I OI, but particularly for the lack of a control group, a properly designed controlled study is warranted.

High i.v. doses of the amino-bisphosphonate neridronate are as effective as infliximab therapy in reducing disease activity in AS patients, with additional benefits on BMD changes. Further studies to confirm these results over a longer time frame are warranted together with the possibility to explore the long-term efficacy of a combination of lower anti-TNF doses with bisphosphonates.

We investigated the short-term effects on bone turnover markers of high doses of vitamin D(3) in order to identify what initial therapeutic dose can be safely administered in vitamin D-deficient subjects. Thirty-seven elderly subjects [mean age 75 ± 3 (SD) years] were consecutively randomized to the administration of a single oral bolus of 600000, 300000, or 100000 IU vitamin D(3). Blood samples were taken at baseline and 1, 3, 7, 14, 30, 60, and 90 days after vitamin D(3) administration. Twenty-four subjects served as controls. No relevant changes in bone turnover markers [C-terminal telopeptides of type I collagen (sCTX) and bone-specific alkaline phosphatase (BAP)] were observed in the controls. In treated patients a dose-dependent effect on sCTX was observed. With the administration of 600,000 IU vitamin D(3) a significant increase of sCTX was observed already at day 1, and it was sustained for 2 months. The changes in sCTX with smaller doses were considerably lower and reached statistical significance only within the first 3 days with the 300,000 IU dose. BAP remained unchanged in patients given 300,000 and 600,000 IU vitamin D(3), while it significantly rose by 15-23 % throughout the observation period in patients given 100,000 IU. Our results indicate that the use of a vitamin D bolus exceeding 100,000 IU may be associated with acute increases of sCTX.

Patients with ankylosing spondylitis (AS) have an increased risk of bone loss and vertebral fractures. In this study, we explored the hypothesis that the excess bone loss and vertebral fractures might be related with the activity of the Wingless signaling pathway, and in particular with the serum levels of its circulating inhibitors, Sclerostin and Dickkopf-1 (DKK1). We recruited 71 patients diagnosed with AS. Lateral radiographs of the total spine were analyzed to detect the presence of vertebral fractures, and bone mineral density (BMD) was assessed in all patients using dual X-ray absorptiometry at lumbar spine and proximal femoral site. Blood samples were obtained and levels of C-reactive protein (CRP), DKK1, and Sclerostin were measured. Blood samples from 71 healthy sex- and age-matched volunteers were collected to be used as controls. Vertebral fractures were detected more commonly among men than in women (29 vs 8 %, respectively). DKK1, but not Sclerostin serum levels, were inversely correlated to lumbar spine Z-score BMD. Patients with one or more prevalent vertebral fractures had significantly higher DKK1 levels, without significant difference in Sclerostin serum levels. A significant positive correlation was found between DKK1 serum levels and CRP (r = 0.240, p = 0.043). The association we found between serum DKK1 levels and BMD values and vertebral fracture prevalence suggests that DKK1 might contribute to the severity of osteoporosis in AS.