Delivery of Soluble FGFR3 as a Treatment for Achondroplasia

递送可溶性 FGFR3 作为软骨发育不全的治疗方法

• 批准号: 7987228
• 负责人: Steven C Ghivizzani
• 金额: $ 32.96万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7987228
• 关键词: Achondroplasia; Address; Affect; Age; Arginine; Binding; Biological; Blood Circulation; Bone Development; Bone Growth; Child; Chondrocytes; Deformity; Differentiation and Growth; Dose; Dwarfism; Epiphysial cartilage; Fibroblast Growth Factor; Gene Delivery; Gene Mutation; Genes; Genotype; Glycine; Growth; Human; Hydrocephalus; Incidence; Intervention; Investigation; Knock-in Mouse; Lead; Ligands; Limb structure; Live Birth; Long-Term Effects; Mediating; Modeling; Mus; Mutation; Neonatal; Paralysed; Patients; Phenotype; Physiology; Point Mutation; Positioning Attribute; Protein Isoforms; Recombinants; Rheumatoid Arthritis; Signal Transduction; Spinal Stenosis; Sudden infant death syndrome; System; TNFR-Fc fusion protein; Transgenic Model; Transgenic Organisms; Transmembrane Domain; Vertebral column; airway obstruction; base; bone; clinical application; cranium; design; fibroblast growth factor receptor 3; gain of function; in vivo; inhibitor/antagonist; long bone; mutant; optimism; public health relevance; quadriceps muscle; receptor; research study; response; skeletal; spine bone structure; vector

DESCRIPTION (provided by applicant): Achondroplasia, the most common form of short-limb dwarfism, occurs in approximately 1 in 30,000 live births. Affected children suffer from abnormal long bone development and deformations of the vertebrae and bones in the skull. There is no cure for achondroplasia, and existing treatments only address some of the complications. Achondroplasia is caused by a mutation in the transmembrane region of fibroblast growth factor receptor-3 (FGFR3). Wild type FGFR3 is one of many inhibitory regulators of endochondral bone growth, and following interaction with FGF ligand acts negatively on both proliferation and terminal differentiation of growth plate chondrocytes. In 98% of those with achondroplasia, the phenotype is caused by a specific point mutation in FGFR3, resulting in the substitution arginine for glycine at position 380 (Gly380Arg). This mutation is one of "gain-of-function," i.e. increased ligand-mediated signaling of FGFR3, which leads to excessive inhibition of bone growth. Similar to the treatment of rheumatoid arthritis through the systemic administration of soluble receptors for tumor necrosis factor 1, we hypothesized that systemic delivery of a soluble FGFR3 molecule would likewise titrate receptor-specific FGF ligands and thereby reduce aberrant FGFR3 signaling to rescue bone growth. Initial experiments in a murine model of achondroplasia generated by transgenic insertion of the murine orthologue of the mutant FGFR3 gene (FGFR3G374R), have shown great promise. Gene delivery of a naturally-occurring, secreted isoform of FGFR3 (FGFR3?TM) to the quadriceps of neonatal achondroplastic mice was found to provide sustained release of FGFR3?TM into the circulation. Appropriate dosing of the gene delivery vector generated levels of circulating FGFR3?TM sufficient to rescue bone growth, such that treated mice were essentially indistinguishable in size from normal littermates at four weeks. The transgenic model has been extremely useful in our proof-of-concept studies. However, certain features may unnaturally influence the amplitude of the biological response to treatment with FGFR3?TM. Therefore, to explore the treatment potential of soluble FGFR3 inhibitors in a context more relevant to the human achondroplasia mutant genotype and phenotype, we will extend these investigations to include the murine FGFR3G374R knock-in achondroplasia model. We will address issues relevant to the mechanisms supporting rescue of skeletal growth and to the potential clinical application of this treatment approach. We will address the following Specific Aims: (1) To determine the capacity of FGFR3?TM to bind FGF-ligand and thereby inhibit aberrant FGFR3G374R signaling in growth plate chondrocytes from transgenic and knock-in models of achondroplasia. (2) To determine the effects of long-term delivery of FGFR3?TM on the skeletal growth and physiology of the FGR3G374R knock-in achondroplasia model. (3) To determine the capacity of administration of a recombinant soluble FGFR3 to rescue bone growth in FGFR3G374Rneo-/+ mice. (4) To determine the relationship between age of intervention and the magnitude of the skeletal response following treatment with soluble FGFR3. PUBLIC HEALTH RELEVANCE: Achondroplasia is the most common form of short-limbed dwarfism. In 98% of cases it is caused by a single genetic mutation in fibroblast growth factor receptor 3 (FGFR3), which regulates the growth of chondrocytes in the growth plates of long bones. The present study is designed to explore a treatment for achondroplasia based on the systemic delivery of soluble forms of FGFR3 that will block the effects of this mutation and restore normal bone growth.

描述(由申请人提供)：软骨发育不全是短肢侏儒症最常见的形式，大约每30,000名活产儿中就有1名发生。受影响的儿童患有长骨发育异常，头骨中的脊椎和骨骼变形。目前还没有治愈软骨发育不全的方法，现有的治疗方法只能解决部分并发症。软骨发育不全是由成纤维细胞生长因子受体-3(FGFR3)跨膜区突变引起的。野生型FGFR3是软骨内骨生长的多种抑制因子之一，与成纤维细胞生长因子配体相互作用对生长板软骨细胞的增殖和终末分化均有负面影响。在98%的软骨发育不全患者中，表型是由FGFR3的特定点突变引起的，导致380位(Gly380Arg)的精氨酸取代甘氨酸。这种突变是一种“功能获得”，即配体介导的FGFR3信号增加，导致过度抑制骨生长。与通过全身注射肿瘤坏死因子1的可溶性受体治疗类风湿性关节炎类似，我们假设全身注射可溶性FGFR3分子同样可以滴定受体特异性的成纤维细胞生长因子配体，从而减少异常的FGFR3信号以挽救骨生长。在转基因插入突变的FGFR3基因(FGFR3G374R)的小鼠软骨发育不全模型上的初步实验显示了巨大的希望。将一种自然产生的、分泌的FGFR3(FGFR3？TM)基因输送到新生软骨再生小鼠股四头肌，可使FGFR3？TM持续释放到循环中。适当剂量的基因传递载体产生了足以挽救骨骼生长的循环FGFR3？TM水平，使得处理后的小鼠在4周时基本上与正常小鼠的大小没有区别。转基因模型在我们的概念验证研究中非常有用。然而，某些特征可能非自然地影响FGFR3？TM治疗的生物反应的幅度。因此，为了在与人类软骨发育不全突变基因和表型更相关的背景下探索可溶性FGFR3抑制剂的治疗潜力，我们将把这些研究扩大到包括小鼠FGFR3G374R敲入软骨发育不全模型。我们将解决与支持挽救骨骼生长的机制以及这种治疗方法的潜在临床应用相关的问题。我们将针对以下特定目标：(1)检测FGFR3？TM结合成纤维细胞生长因子配体的能力，从而抑制转基因和敲入软骨发育不全模型中生长板软骨细胞中异常的FGFR3G374R信号。(2)探讨长期应用FGFR3？TM对FGR3G374R敲入型软骨发育不全模型大鼠骨骼生长和生理的影响。(3)检测重组可溶性FGFR3对FGFR3G374Rneo-/+小鼠骨生长的修复作用。(4)探讨干预年龄与可溶性FGFR3治疗后骨骼反应大小的关系。 与公共卫生相关：软骨发育不全是最常见的短肢侏儒症。在98%的病例中，它是由成纤维细胞生长因子受体3(FGFR3)的单一基因突变引起的，FGFR3调节长骨生长板中软骨细胞的生长。本研究旨在探索一种基于全身注射可溶性形式的FGFR3的软骨发育不全的治疗方法，该方法将阻断这种突变的影响，并恢复正常的骨生长。