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

为了确保年迈的退伍军人在尽可能少的肌肉骨骼疼痛的情况下保持活跃和活动，新的 预防骨质疏松症和促进骨折后及时骨再生的方法有 这是必要的。这项合作研究汇集了一组退伍军人管理局调查人员，他们具有不同的 疾病模型的观点和洞察力以及互补的技术专长，以协同应对 主要的临床问题。即骨折，导致退伍军人的高发病率和死亡率。这个 每个综合项目的总体研究策略是使用疾病的临床前模型，这些模型要么削弱 骨修复或延缓骨修复，探索增强甲状旁腺激素(PTH)能力的新方法 促进骨形成，并以统一、严格的方式评估骨骼疾病和治疗效果。 本已诊断和治疗不足的骨质疏松症可能会增加脆性骨折的数量 在退伍军人医院接受治疗，而没有新的早期发现工具和新的治疗策略， 避免目前抑制骨丢失的治疗方法罕见但具有破坏性的副作用。解决这个未满足的问题 临床需要，总体目标是确定治疗策略，以改善退伍军人和 增强甲状旁腺素信号的骨合成代谢。这项合作将解决最重要的假设： 健康问题对退伍军人的影响不成比例地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，从而改善 骨质疏松症的临床治疗在于了解这些健康问题是如何损害骨骼健康的。 这一具体的建议是基于大量研究，这些研究证明了钙离子- 敏感受体(CaSR)通过拮抗促钙活性介导全身矿物质动态平衡 甲状旁腺素的作用和甲状旁腺素对骨骼的合成代谢作用的协同作用，以及最近的研究表明 长效PTH1-34/PTHrP杂合类似物，即LAPTh的合成代谢作用。我们将检验这一假设 与LAPTh联合注射拟钙剂比目前的注射产生更强大的骨合成代谢 PTH1-34疗法在不产生高钙血症的情况下加速衰老或雌激素缺乏的康复- 通过3种高度整合的方式激活成熟OB、OCY和OCL中的CASR，从而诱导骨质疏松骨骼 明确的目标。目标1将首先确定LAPTh/拟钙化联合方案的临床相关性 (A)优化在不产生高钙血症的情况下最大限度地促进骨骼合成代谢所需的药物剂量 以及老年雄性小鼠和去卵巢小鼠的相关并发症；以及(B)确定一种 需要进行抗吸收治疗，以保留新形成的骨，并最终抵抗以下骨折 综合治疗。目标2将(A)确定成熟OB/骨细胞中CaSR在调节合成代谢中的作用。 LAPTh/NPS-R568联合治疗对矿物质和骨骼参数变化的影响 和其CaSR基因在这些细胞中被去除的小鼠的周围重建(PLR)活动； 通过比较化合物单独和在不同环境中的作用，揭示潜在的细胞自主机制 原代和成骨细胞增殖、存活、分化和矿化功能的联合作用 培养中有或不有CaSR过表达或敲除的骨细胞MLO-Y4细胞；以及(C)阐明 单细胞活体成像研究成熟期OBS和MLO-Y4细胞中CaSR和PTH1R之间的信号串扰 技术目标3将(A)确定OCL CaSR在预防高钙血症和在 评价LAPTh/NPS-R568联合治疗对骨代谢的影响 以及在OCL中敲除CaSR基因的小鼠的骨骼动态平衡；和(B)定义潜在的 通过检测化合物对生长、存活、分化和骨骼的影响来探讨其作用机制。 过度表达或缺乏CaSR的培养OCL的功能恢复。这项研究的成功完成将 为设计更有效治疗骨质疏松症的“首例人”试验提供必要的信息。

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.