open access

https://hdl.handle.net/2115/56613

Vitamin K-dependent carboxylation of osteocalcin affects the efficacy of teriparatide (PTH1-34) for skeletal repair

英語

Parathyroid hormone (1-34)

2014-07

Elsevier

Bone

64

95-101

Teriparatide (PTH1-34) promotes skeletal repair and increases bone mass. Vitamin K is involved in bone mineralization as a coenzyme of gamma-carboxylase for Gla proteins, and therefore vitamin K insufficiency caused by malnutrition or therapeutic intake of the vitamin K antagonist warfarin could affect the efficacy of PTH1-34 therapy for bone repair. In the present study, we investigated whether vitamin K influences the efficacy of PTH1-34 therapy for bone repair in a rat osteotomy model. Female 12-week-old Sprague-Dawley rats were subjected to a closed midshaft osteotomy of the femur and randomized into four groups (n = 10 per group): vehicle, PTH1-34 (daily 30 mu g/kg/day subcutaneous injection) + solvent (orally, three times a week), PTh1-34 + warfarin (0.4 mg/kg/day orally, three times a week), and PTH1-34 + vitamin K-2 (menatetrenone, 30 mg/kg/day orally, three times a week). Serum gamma-carboxylated and uncarboxylated osteocalcin (Gla-OC and Glu-OC) levels and radiographic healing were monitored every 2 weeks. Skeletal repair was assessed by micro-computed tomography, mechanical testing, and histology at 8 weeks after surgery. PTH1-34 amplified the osteotomy-induced increase in Gla-OC and improved the mechanical properties as well as the volumetric bone mineral tissue density of the fracture callus. Concurrent use of warfarin decreased the response to PTH1-34 therapy in terms of mechanical recovery, probably by impairing mineralization due to the lack of Gla-OC. Although the effects of combination therapy with PTH1-34 and vitamin K-2 on bone repair did not significantly exceed those of PTH1-34 monotherapy in rats fed sufficient dietary vitamin K, postoperative Gla-OC levels were correlated with the mechanical properties of the osteotomized femur in PTH1-34-treated rats regardless of the use of warfarin or vitamin K-2. These findings suggest the importance of vitamin K dependent gamma-carboxylation of DC for realizing the full effects of PTH1-34 on skeletal repair. (C) 2014 Elsevier Inc. All rights reserved.

学術雑誌論文

Accepted Manuscript

8756-3282