The effect of teriparatide treatment on circulating periostin and its relationship to regulators of bone formation and BMD in postmenopausal women with osteoporosis

Context: Treatment of postmenopausal osteoporosis with teriparatide (PTH 1-34) increases bone formation and improves bone microarchitecture. A possible modulator of this mechanism of action is periostin. In vitro experiments have shown that periostin may regulate osteoblast differentiation and bone formation through Wnt signaling. Periostin secretion is increased by PTH in preclinical models, but the effect of teriparatide treatment of postmenopausal osteoporosis on periostin is not currently known. Objectives, to: i) determine the effect of teriparatide treatment on circulating levels of periostin and other regulators of bone formation and ii) investigate how changes in periostin relate to changes in bone turnover markers, regulators of bone formation and bone mineral density. Participants and design: 20 women with postmenopausal osteoporosis, a two-year open-label single-arm study. Intervention: Teriparatide 20 mcg was administered by subcutaneous injection daily over 104 weeks. Periostin, sclerostin and DKK-1, PINP and CTX were measured in fasting serum collected at baseline (two visits) then at weeks 1,2,4,12,26,52,78 and 104. BMD was measured at the lumbar spine, total hip and femoral neck by DXA. Results: Periostin levels increased by 6.6% (95% CI -0.4, 13.5) after 26 weeks teriparatide treatment and significantly by 12.5% (95% CI 3.3,21.0, P<0.01) after 52 weeks. Change in periostin was positively correlated with change in lumbar spine BMD at week 52 (r=0.567(95% CI 0.137,0.817), P<0.05) and femoral neck BMD at week 104(r=0.682(95% CI 0.261,0.885), P<0.01). Conclusion: Teriparatide therapy increases periostin secretion; it is unclear whether this increase mediates the effect of the drug on bone.