Mutations in Osteoprotegerin Cause Calcium Pyrophosphate Deposition Disease

护骨素突变导致焦磷酸钙沉积病

基本信息

批准号：
10159843
负责人：
Ann K Rosenthal
金额：
--
依托单位：
CLEMENT J. ZABLOCKI VA MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-01-01 至 2022-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10159843
关键词：
Affect Affinity American Amino Acids Arthritis Behavior Binding Biological Markers Bone Density Calcium Pyrophosphate Calcium pyrophosphate deposition disease Cell membrane Cell surface Characteristics Chondrocytes Chromatography Clinical Code Crystal Formation Crystallization Data Dimerization Disease Disease Clusterings Elderly Goals Heparin Binding Heparitin Sulfate ICD-9 IGF1 gene In Vitro Measures Membrane Molecular Abnormality Molecular Sieve Chromatography Mutation NF-kappa B Osteoblasts Osteoclasts Osteopenia Pain Pathway interactions Patients Pattern Pharmaceutical Preparations Phenotype Proteins Publishing Recombinants Reporting Risk Factors Roentgen Rays Role Structure Surface Plasmon Resonance TNF-related apoptosis-inducing ligand TNFRSF11B gene TNFSF10 gene TRANCE protein Terminator Codon Tissues Transforming Growth Factor beta Tumor necrosis factor receptor 11b Veterans Work articular cartilage dimer disease phenotype early onset effective therapy gain of function gain of function mutation in vivo Model innovation joint destruction joint injury kindred loss of function military veteran new therapeutic target novel therapeutics older patient osteoclastogenesis premature prevent receptor receptor binding stem subchondral bone

项目摘要

Calcium pyrophosphate deposition disease (CPDD) is a common type of arthritis defined by the presence of calcium pyrophosphate (CPP) crystals in articular cartilage. It is particularly common in the US Veteran population as risk factors for CPDD including advanced age and prior joint trauma are highly prevalent in American Veterans. We recently published a study of US veterans using ICD-9 codes to identify 29,000 American Veterans with the disease in a single 5-year period. While CPDD affects elderly patients in a sporadic fashion, it also occurs prematurely in familial patterns. Studies of familial forms of this disease present exciting opportunities to identify novel therapeutic targets for this currently untreatable arthritis. We recently confirmed that a mutation in the stop codon of TNFRSF11B causes early onset CPDD. TNFRSF11B codes for osteoprotegerin (OPG). The OPG mutation causing CPDD (mtOPG) results in an additional 19 amino acids added to the protein's C terminus near the heparin binding domain. OPG is decoy receptor for receptor activator of nuclear factor kappa B ligand (RANKL). RANKL promotes osteoclast formation, and because OPG blocks its function, reduction of OPG activity results in increased osteoclastogenesis. The phenotype of affected patients with this mutation includes exuberant CPP crystal formation, mild osteopenia and severe joint degeneration, a phenotype consistent with a loss of function of OPG. Indeed, preliminary data demonstrate that recombinant mtOPG displays inefficient inhibition of membrane-bound RANKL resulting in excess osteoclastogenesis in vitro. Interestingly, osteoclast conditioned media potently stimulates biomarkers of CPP crystal formation in chondrocytes. The purpose of this work is to investigate the conceptually innovative hypothesis that mtOPG produces CPDD by increasing osteoclastogenesis in subchondral bone. In specific aim 1, using in vitro and in vivo models, we will show that compared to wild type OPG (wtOPG), mtOPG ineffectively binds to the osteoblast cell membrane. resulting in excess un-opposed membrane-bound RANKL and increased osteoclast formation. Overabundant osteoclasts in subchondral bone produce joint damage and release CPP crystal-promoting factors into articular cartilage. In the second aim, structural studies using chromatography, surface plasmon resonance and small angle x-ray scattering, will demonstrate reduced affinity of mtOPG to bind heparan sulfate and decreased dimerization. The scientific premise of this work stems from careful observations of the phenotype of patients with the OPG mutation and is supported by preliminary in vitro functional studies of mtOPG. These studies are the first to identify the OPG/RANKL/RANK pathway in CPDD and to implicate subchondral bone as a target tissue in this disease. The shared clinical features of patients with CCAL1 and those with sporadic CPDD as well as the existence of available drugs which target this pathway make this work particularly exciting.

焦磷酸钙沉积病（CPDD）是一种常见的关节炎类型，定义为关节软骨中存在焦磷酸钙（CPP）晶体。它特别是在美国退伍军人群体中，常见的 CPDD 危险因素包括高龄和先前的关节创伤在美国退伍军人中非常普遍。我们最近发表了一项研究美国退伍军人使用 ICD-9 代码识别出 29,000 名患有该疾病的美国退伍军人单次5年期。虽然 CPDD 偶尔会影响老年患者，但它也会发生过早地出现在家庭模式中。对这种疾病的家族形式的研究令人兴奋为这种目前无法治疗的关节炎确定新的治疗靶点的机会。我们最近证实，TNFRSF11B 终止密码子的突变导致早发 CPDD。 TNFRSF11B 编码骨保护素 (OPG)。 OPG 突变导致 CPDD (mtOPG) 结果在肝素附近的蛋白质 C 末端添加了额外的 19 个氨基酸结合域。 OPG 是核因子 kappa B 配体受体激活剂的诱饵受体（兰克）。 RANKL 促进破骨细胞形成，并且由于 OPG 阻断其功能， OPG 活性的降低导致破骨细胞生成增加。受影响的表型患有这种突变的患者包括丰富的 CPP 晶体形成、轻度骨质减少和严重的关节退化，这种表型与 OPG 功能丧失一致。的确，初步数据表明重组 mtOPG 对膜结合的 RANKL 导致体外破骨细胞生成过多。有趣的是，破骨细胞条件培养基有效刺激 CPP 晶体形成的生物标志物软骨细胞。这项工作的目的是研究概念上的创新 mtOPG 通过增加破骨细胞生成产生 CPDD 的假设软骨下骨。在具体目标 1 中，使用体外和体内模型，我们将证明与野生型 OPG (wtOPG) 相比，mtOPG 与成骨细胞的结合无效膜。导致过量的非相对膜结合 RANKL 和破骨细胞增加形成。软骨下骨中过多的破骨细胞会导致关节损伤和释放 CPP晶体促进因子进入关节软骨。在第二个目标中，使用结构研究色谱法、表面等离子体共振和小角 X 射线散射，将证明 mtOPG 与硫酸乙酰肝素结合的亲和力降低并减少二聚化。科学的这项工作的前提源于对 OPG 患者表型的仔细观察 mtOPG 的初步体外功能研究支持了突变。这些研究是第一个发现 CPDD 中的 OPG/RANKL/RANK 通路并涉及软骨下骨作为这种疾病的靶组织。 CCAL1 患者与其他患者的共同临床特征散发性 CPDD 以及针对该途径的可用药物的存在使得这项工作特别令人兴奋。