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: 8675729
• 负责人: Steven C Ghivizzani
• 金额: $ 31.01万
• 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 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8675729
• 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; 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.

描述（由申请人提供）：Achondroplasia是最常见的短期矮人形式，大约有30,000例活产。受影响的儿童患有异常的长骨发育，椎骨和骨骼的变形。无法治愈酸性的肿瘤，现有治疗只能解决一些并发症。疼痛质质是由成纤维细胞生长因子受体-3（FGFR3）的跨膜区域突变引起的。野生型FGFR3是众多内软骨骨生长的抑制性调节剂之一，在与FGF配体相互作用后，对生长板软骨细胞的增殖和终末分化均负有负面作用。在98％的疼痛质症的人中，表型是由FGFR3中的特定点突变引起的，导致在位置380（Gly380arg）处的甘氨酸取代精氨酸。该突变是“功能收益”之一，即FGFR3的配体介导的信号增加，这导致过度抑制骨骼生长。类似于通过全身施用可溶性受体用于肿瘤坏死因子1的治疗类风湿关节炎，我们假设全身递送可溶性FGFR3分子同样会滴定受体特异性FGF配体，从而减少异常的FGFR3信号以挽救骨骼生长。通过转基因插入突变体FGFR3基因（FGFR3G374R）的鼠直系同源物产生的藻类模型中的初步实验，已经显示出很大的希望。发现基因递送FGFR3（FGFR3？tm）的天然分泌的同工型向新生儿促塑性小鼠的股四头肌传递，可在循环中持续释放FGFR3？tm。适当的基因递送载体的剂量产生的循环FGFR3？TM水平足以挽救骨骼的生长，因此，在四个星期时，经过治疗的小鼠与正常同窝仔的大小基本上是无法区分的。转基因模型在我们的概念验证研究中非常有用。但是，某些特征可能会不自然地影响使用FGFR3？tm治疗的生物学反应的幅度。因此，为了探索与人疼痛性突变基因型和表型更相关的环境中可溶性FGFR3抑制剂的治疗潜力，我们将扩展这些研究，以包括鼠FGFR3G374R敲击Anconondroploploploploploploploplasia模型。我们将解决与支持骨骼生长的机制以及与该治疗方法的潜在临床应用有关的问题。我们将解决以下特定目的：（1）确定FGFR3？tm结合FGF-rigand的能力，从而在生长板软骨细胞中抑制异常质基细胞的生长板软骨细胞中的异常FGFR3G374R信号传导。 （2）确定FGFR3？tm长期递送对FGR3G374R敲击刺激性的骨骼生长和生理学的影响。 （3）确定重组可溶性FGFR3的施用能力，以挽救FGFR3G374RNEO-/+小鼠中骨骼生长的能力。 （4）确定干预年龄与可溶性FGFR3处理后的骨骼反应之间的关系。