Symptomatic and Functional Biomarkers of IVD Degeneration in a Small Animal Model

描述（由申请人提供）：椎间盘（IVD）退变是一种复杂的肌肉骨骼病理，其特征是脊柱的早期解剖改变，可能与患者活动能力下降和症状性疼痛增加有关。在动物模型中，疼痛敏感性、步态和运动协调已被证明是退行性肌肉骨骼和炎症病理（如关节炎）的反映。这些措施有可能作为微创生物标志物转化为人类病理，但尚未在IVD变性模型中得到很好的研究。IVD变性与IX型胶原编码基因的单核苷酸突变之间存在很强的遗传联系。最近，Col9a1基因失活（IX型胶原敲除）的小鼠被证明会自发和过早地发生IVD变性，包括蛋白聚糖含量的变化、细胞死亡和类似人类疾病的关节形态。本提案将在IX型胶原敲除小鼠中测试IVD退行性变的功能、症状和解剖标记之间的关系，以验证IVD退行性改变可以通过疼痛敏感性、步态和运动协调等微创、非牺牲性生物标记来检测的假设。将采用纵向试验设计来检测基因敲除小鼠在6周、12周、24周和48周时过早发生的退行性变化以及相关的症状或功能变化。疼痛敏感性将通过von Frey细丝（机械异常性痛）和热足底和尾轻弹试验（热痛觉过敏）进行评估。步态将使用高速数字视频记录，并分析量化速度，肢体支撑阶段，对称性，步宽和步长。此外，运动协调性将通过旋转跑步机、吊绳、走杆和握力测试进行评估。然后，这些症状和功能数据将与通过MRI和组织学评估的IVD退行性改变的测量相关联。作为IVD退变的微创、非牺牲性生物标志物，这些参数可用于快速筛选疾病干预的影响，跟踪与IVD病理相关的症状性疼痛和功能丧失的时间变化，评估由IVD退变指导的行为选择和功能限制，并提供一种新型小动物模型的疼痛和功能表征。申请人将学习成像、步态分析和症状性疼痛评估方面的新方法，这将促进申请人的职业发展和这些生物标志物在人类疾病研究中的翻译。因此，本提案的目的是评估这些生物标志物在IVD变性新模型中的功效。

DESCRIPTION (provided by applicant): Intervertebral disc (IVD) degeneration is a complex musculoskeletal pathology characterized by early onset of anatomical changes in the spine that may be associated with decreased patient mobility and increased symptomatic pain. In animal models, pain sensitivity, gait, and motor coordination have been shown to be reflective of degenerative musculoskeletal and inflammatory pathologies, such as arthritis. These measures have the potential to serve as minimally invasive biomarkers that translate to human pathology, but have not been well studied in models of IVD degeneration. Strong genetic links have been identified between IVD degeneration and single nucleotide mutations in genes encoding type IX collagen. Recently, mice with an inactivation of the Col9a1 gene (type IX collagen knockout) have been shown to spontaneously and prematurely develop IVD degeneration, including changes in proteoglycan content, cell death, and joint morphology that resemble human disease. This proposal will test for a relationship between functional, symptomatic, and anatomic markers of IVD degeneration in type IX collagen knockout mice to test the hypothesis that IVD degenerative changes can be detected through minimally invasive, non-sacrificial biomarkers of pain sensitivity, gait, and motor coordination. A longitudinal test design will be employed to detect premature onset of degenerative changes in knockout mice and associated symptomatic or functional changes at 6, 12, 24, and 48 weeks. Pain sensitivity will be evaluated using von Frey filaments (mechanical allodynia) and thermal plantar and tail flick tests (thermal hyperalgesia). Gait will be recorded using high speed digital video, and analyzed to quantify velocity, limb support phases, symmetry, step width, and stride length. Additionally, motor coordination will be assessed using rotarod treadmill, wire-hang, pole walking, and grip strength tests. These symptomatic and functional data will then be correlated to measures of IVD degenerative changes as assessed by MRI and histology. As minimally invasive, non-sacrificial biomarkers of IVD degeneration, these parameters may be used to rapidly screen the effects of disease interventions, track temporal changes in symptomatic pain and functional losses associated with IVD pathology, assess behavioral selection and functional limits directed by IVD degeneration, and provide a pain and functional characterization of a novel small animal model. The applicant will learn new methodologies in imaging, gait analysis, and symptomatic pain assessments, that will advance both the applicant's career and the translation of these biomarkers for the study of human disease. Thus, the objective of this proposal is to assess the efficacy of these biomarkers in a novel model of IVD degeneration.