Mechanisms of bone fragility in Autosomal Dominant Osteopetrosis type II: from human to mouse and back

常染色体显性骨硬化症 II 型骨脆性机制：从人到小鼠再到背部

基本信息

批准号：
10366576
负责人：
Thomas Levin Geiser Andersen
金额：
$ 49.48万
依托单位：
BRIGHAM AND WOMEN'S HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-09-01 至 2027-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10366576
关键词：
Affect Age Albers-Schonberg disease Antibody Therapy Automobile Driving Back Biomechanics Biopsy Specimen Bone Diseases Bone Marrow Transplantation Bone Resorption Bone remodeling Bone structure CD14 gene Caring Cell Nucleus Cells Characteristics Coculture Techniques Communication Complement Computer Assisted Coupling Data Development Disease Elderly Endosteal Cell Family Future Genes Genetic Transcription Goals Human Image In Situ Hybridization In Vitro Inherited Investigation Knowledge Mature Bone Mediating Molecular Mus Mutation Osteoblasts Osteoclasts Osteogenesis Osteoporosis Pathologic Patients Peripheral Phenotype Physiological Physiology Process Resources Sampling Scallop Skeletal bone TNFSF11 gene Testing Withdrawal Work base bone bone fragility bone loss bone mass cell type cost human model in vivo innovation insight lens monocyte mouse model multimodality novel novel therapeutics overexpression progenitor programs sex skeletal therapeutic target tool transcriptome sequencing transcriptomics translational impact treatment strategy

项目摘要

SUMMARY Coupling, or communication between the bone-resorbing osteoclasts and bone-forming osteoblasts during bone remodeling, is a key step in the bone remodeling cycle. While compelling evidence shows that bone loss and fragility with age and osteoporosis result from corrupted coupling, the precise mechanism of osteoclast- osteoblast communication remains unclear. Thus, although stimulating coupling is a theoretically attractive therapeutic target, current treatments for osteoporosis, a common disorder affecting 54 million of the elderly in the US alone, are limited to either inhibiting osteoclastic bone resorption or stimulating osteoblastic bone formation. Our long-term goal is to determine the mechanism of osteoclast-osteoblast communication critical for coupling of bone formation to resorption during physiological bone remodeling, using rare osteopetrotic diseases as a tool. Rare bone diseases provide important insights into typical bone physiology and knowledge gained from these diseases has already led to new therapies for osteoporosis. In this proposal, we utilize samples from patients with autosomal dominant osteopetrosis type II (ADOII), a rare inheritable osteopetrosis characterized by high bone mass and skeletal fragility and complement human studies with mouse models. ADOII results from heterozygous mutations in the CLCN7 gene, which encodes the ClC-7 Cl-/H+ exchanger essential for osteoclastic bone-resorption. While the lack of osteoclastic resorption clearly contributes to bone phenotype, bone formation is also inappropriately high. In preliminary data investigating the bone structural unit (BSU) composition of ADOII bones, we found bone formation is primarily remodeling based, with excess bone formation called overflow remodeling. Osteoclasts are abundant and scalloped cement lines suggest an intermittent pit-like resorption mode, which in combination with overflow remodeling results in a characteristic puzzle-like bone structure. We hypothesize that the anabolically active but poorly resorptive osteoclasts in ADOII overexpress anabolic coupling factors, inappropriately stimulating bone formation to overfill the resorbed cavities and leading to disorganized puzzle-like bone and fragility. We will test this hypothesis by combining in vivo and in vitro studies of ADOII patients and mouse models, multimodal and multiscale imaging, biomechanics and spatial/single-nuclei transcriptomics. Specifically, we will: 1) test if the high bone mass and fragility in human and mouse ADOII is osteoclast-mediated; and 2) investigate the mechanism of inappropriately high bone formation in ADOII by single nuclei transcriptomic analysis of physically adjacent osteoclasts and osteoblasts. The proposed studies take advantage of the unique resource of extant iliac crest bone biopsy specimens from 15 ADOII patients from a Danish family carrying the CLCN7 (G215R) mutation and age and sex matched controls, and two mouse models of ADOII, including the analogous Clcn7G213R/+ mutation. Through the lens of ADOII, these studies will provide unique insights into osteoclast-osteoblast communication.

概括骨吸收破骨细胞和骨形成成骨细胞之间的耦合或通讯在骨重建过程中，是骨重建周期的关键步骤。虽然令人信服的证据表明骨随着年龄的增长和骨质疏松症，骨质疏松症的损失和脆弱性是由破骨细胞的精确机制——耦合破坏造成的。成骨细胞的通讯仍不清楚。因此，尽管刺激耦合在理论上很有吸引力治疗目标、骨质疏松症的当前治疗方法，骨质疏松症是一种影响 5400 万老年人的常见疾病仅美国，仅限于抑制破骨细胞骨吸收或刺激成骨细胞骨形成。我们的长期目标是确定破骨细胞-成骨细胞通讯的机制，这对于利用罕见的骨石症疾病，在生理性骨重塑过程中骨形成与骨吸收的耦合作为一种工具。罕见骨病提供了对典型骨生理学和所获得知识的重要见解这些疾病已经导致骨质疏松症的新疗法。在本提案中，我们利用来自常染色体显性骨石症 II 型 (ADOII) 患者的样本，一种罕见的遗传性骨石症，其特征是高骨量和骨骼脆弱性，可补充人类用小鼠模型进行研究。 ADOII 是由 CLCN7 基因杂合突变引起的，该基因编码 ClC-7 Cl-/H+ 交换剂对于破骨细胞骨吸收至关重要。虽然缺乏破骨细胞吸收明显有助于骨表型，骨形成也过高。初步数据显示研究 ADOII 骨骼的骨结构单元 (BSU) 组成，我们发现骨形成主要是以重塑为基础，过量的骨形成称为溢出重塑。破骨细胞丰富且扇形水泥线表明间歇性凹坑状吸收模式，与溢出相结合重塑产生了典型的拼图状骨骼结构。我们假设合成代谢活跃但 ADOII 中吸收不良的破骨细胞过度表达合成代谢耦合因子，不适当地刺激骨骼形成过度填充再吸收的空腔并导致混乱的拼图状骨骼和脆弱性。我们将通过结合 ADOII 患者和小鼠模型的体内和体外研究来检验这一假设，多模式和多尺度成像、生物力学和空间/单核转录组学。具体来说，我们将： 1）测试人和小鼠ADOII的高骨量和脆性是否是破骨细胞介导的；和 2) 研究单核 ADOII 中不适当的高骨形成机制物理相邻的破骨细胞和成骨细胞的转录组分析。拟议的研究利用了现存髂嵴骨活检标本的独特资源来自丹麦家庭的 15 名 ADOII 患者，携带 CLCN7 (G215R) 突变，且年龄和性别匹配对照，以及两种 ADOII 小鼠模型，包括类似的 Clcn7G213R/+ 突变。透过镜头 ADOII，这些研究将为破骨细胞-成骨细胞通讯提供独特的见解。