BCCMA: Foundational Research to Act Upon and Resist Conditions Unfavorable to Bone (FRACTURE CURB): Combined long-acting PTH and calcimimetics actions on skeletal anabolism

为了确保老年退伍军人保持活跃和移动的尽可能少的肌肉骨骼疼痛，新的 预防骨质疏松症和促进骨折后及时骨再生的方法是 必要这项合作研究汇集了一组VA调查人员， 疾病模型的观点和见解以及互补的技术专门知识，以协同打击 严重的临床问题也就是说，骨折，导致退伍军人的高发病率和死亡率。的 每个综合项目的总体研究战略是使用疾病的临床前模型， 骨或延迟骨修复，研究新的方法来提高甲状旁腺激素（PTH）的能力， 促进骨形成，并以统一、严格的方式评估疾病和治疗对骨的影响。 骨质疏松症已经诊断不足和治疗不足，很可能会增加脆性骨折的数量 在VA医院接受治疗，没有新的早期检测工具和新的治疗策略， 避免了目前抑制骨质流失的疗法的罕见但毁灭性的副作用。解决未解决的问题 临床需要，总体目标是确定治疗策略，以改善退伍军人的骨骼健康， 以增强PTH信号传导的骨抑制作用。合作将解决总体假设： 不成比例地影响退伍军人的健康问题激活了增加骨吸收的信号通路， 抑制骨形成或阻碍骨折骨痂中软骨向骨的转变， 在骨质疏松症的临床管理在于了解这些健康问题如何损害骨骼健康。 这个具体的建议是基于大量的调查，证明了核心作用的Ca 2 +- 钙敏感受体（CaSR）通过对抗促钙活性介导全身矿物质稳态 PTH和协同PTH对骨的合成代谢作用，以及最近的研究表明， 长效PTH 1 -34/PTHrP杂合类似物，即LAPTH的合成代谢作用。我们将检验这个假设 模拟钙剂与LAPTH的联合注射产生了比目前更强大的骨抑制作用， PTH 1 -34治疗不产生高钙血症，以加速衰老或雌激素缺乏的康复 通过激活成熟OBs、OCYs和OCL中的CaSRs，通过3种高度整合的 具体目标。目的1将首先通过以下方法确定LAPTH/拟钙剂联合方案的临床相关性： (a)优化产生最大骨骼肌张力而不产生高钙血症所需的药物剂量 以及衰老雄性小鼠和卵巢切除小鼠中的相关并发症;以及（B）确定是否存在 需要抗再吸收治疗以保持新形成的骨并最终抵抗骨折 联合治疗。目的2将（a）确定成熟OB/骨细胞中CaSR在介导合成代谢中的作用， LAPTH/NPS-R568联合治疗的作用，评估矿物质和骨骼参数的变化 和在那些细胞中具有其Casr基因消融的小鼠中的泡周重塑（PLR）活性;（B）描绘 潜在的细胞自主机制，通过比较化合物的影响，单独和在 组合对原代OB的增殖、存活、分化和矿化功能的影响， 在培养物中有或没有CaSR过表达或敲低的骨细胞MLO-Y 4细胞;和（c）阐明 通过单活细胞成像在成熟OB和MLO-Y 4细胞中CaSR和PTH 1 R之间的信号传导串扰 技术.目的3将（a）确定OCL CaSR在预防高钙血症发展中的作用， 通过评估矿物质的变化介导LAPTH/NPS-R568联合治疗的骨合成代谢作用 和OCL中Casr基因敲除的小鼠中的骨骼稳态;和（B）定义潜在的 通过检查化合物对生长、存活、分化和骨形成的影响， 过度表达或缺乏CaSR的培养OCL的再吸收功能。成功完成研究将 为更有效治疗骨质疏松症的“首次人体”试验设计提供重要信息。

To ensure aging Veterans remain active and mobile with as little musculoskeletal pain as possible, new approaches to the prevention of osteoporosis and promotion of timely bone regeneration following a fracture are necessary. This collaborative research study brings together a group of VA investigators with diverse perspectives and insights of disease models and complementary technical expertise, to synergistically attack a major clinical problem. i.e., a bone fracture, that leads to high morbidity and mortality among Veterans. The overall research strategy of each integrated project is to use pre-clinical models of diseases that either weaken bone or delay bone repair, to investigate novel ways to enhance the ability of parathyroid hormone (PTH) to promote bone formation, and to assess disease and treatment effects on bone in a unified, stringent manner. Already under-diagnosed and under-treated, osteoporosis is likely to increase the number of fragility fractures being treated at VA hospitals without novel tools for early detection and novel treatment strategies that circumvent the rare but devastating side effects of current therapies that inhibit bone loss. Addressing this unmet clinical need, the overall aims are to identify therapeutic strategies to improve bone health among Veterans and to enhance the bone anabolism of PTH signaling. The collaboration will address the overarching hypothesis: health problems disproportionately affecting Veterans activate signaling pathways that increase bone resorption, suppress bone formation, or impede the transition of cartilage to bone in a fracture callus such that improvements in the clinical management of osteoporosis lie in understanding how these health problems hurt bone health. This specific proposal is based on a large body of investigations that demonstrate a central role of the Ca2+- sensing receptor (CaSR) in mediating systemic mineral homeostasis by counteracting the calciotropic activities of PTH and in synergizing the anabolic effects of PTH on bone as well as the recent studies that show robust anabolic actions of a long-acting PTH1-34/PTHrP hybrid analog, namely, LAPTH. We will test the hypothesis that co-injections of calcimimetics with LAPTH produce much more robust osteoanabolism than the current PTH1-34 therapy without producing hypercalcemia to accelerate rehabilitation of aging- or estrogen deficiency- induced osteoporotic skeletons by activating CaSRs in mature OBs, OCYs, and OCLs through 3 highly integrated specific Aims. Aim 1 will first establish the clinical relevance of the combined LAPTH/calcimimetic regimen by (a) optimizing the drug doses needed to produce maximal skeletal anabolism without producing hypercalcemia and the related complications in aging male mice and ovariectomized mice; and (b) determining whether an antiresorptive treatment is required to retain the newly formed bone and ultimately resist bone fracture following the combined treatment. Aim 2 will (a) define the role of CaSR in mature OB/osteocytes in mediating the anabolic actions of the combined LAPTH/NPS-R568 treatment by assessing changes in mineral and skeletal parameters and perilacunar remodeling (PLR) activities in mice with their Casr genes ablated in those cells; (b) delineate the underlying cell-autonomous mechanisms by comparing the effects of the compounds individually and in combination on the proliferation, survival, differentiation, and mineralizing functions of primary OBs and osteocytic MLO-Y4 cells with or without CaSR overexpression or knockdown in culture; and (c) elucidate signaling cross-talk between CaSR and PTH1R in mature OBs and MLO-Y4 cells by single live cell imaging technology. Aim 3 will (a) define the role of OCL CaSR in preventing the development of hypercalcemia and in mediating osteoanabolic effects of the combined LAPTH/NPS-R568 treatment by assessing changes in mineral and skeletal homeostasis in mice with their Casr genes knocked-out in OCLs; and (b) define the underlying mechanisms by examining the effects of the compounds on the growth, survival, differentiation, and bone- resorbing functions of cultured OCLs overexpressing or lacking CaSR. Successful completion of the study will provide essential information for designs of “first-in-man” trials for more effective treatments of osteoporosis.