OA Pathogenesis beyond Cartilage: A preclinical study of the sources of OA pain

项目摘要 2010年一项名为“对抗关节炎疼痛”的公众宣传活动宣传移动是最好的药物！ 虽然临床研究压倒性地证实运动是一种有效的骨关节炎（OA）治疗，但患者通常 我觉得这个建议是违反直觉的--“治疗关节疼痛的方法就是多用它？”这种混乱的部分原因是 以软骨为中心的OA定义，这意味着更多的软骨损伤将导致更多的疼痛。然而，在这方面， OA是一种“关节作为一个器官的疾病”，整个关节都发生变化。此外， 影响OA疼痛和残疾发生在关节内和关节外，包括关节结构的变化， 炎症和神经可塑性。了解这些复杂因素如何影响患者的主要 疼痛和残疾等问题可以帮助确定OA治疗的关键目标。 临床前OA模型应该是一个强大的工具，以帮助研究人员确定OA之间的生理联系 发病机制和病理学，提供了一个机会，调查方面的OA，不能轻易 在人类身上探索。为了实现这一目标，这项建议将使用新的啮齿动物步态分析和措施后， 肢体敏感性，以研究关节结构、关节内炎症和背根神经节的变化 大鼠膝关节创伤后OA相关疼痛和功能障碍的神经可塑性研究 OA。首先，将使用nanoCT在我们的模型中获得骨骼结构的3D测量，并且将获得骨骼结构的3D变化。 软骨和滑膜将使用选择性平面照明显微镜（SPIM）进行评估， 清理膝关节（目标1）。这一目标将使我们能够研究复杂的3D关节结构之间的关系 和OA相关的疼痛和残疾。其次，OA发病机制和OA疼痛之间的缺失环节往往是 假设是炎症，其可以在关节结构中没有重大变化的情况下暂时循环。在这一提议中， 在我们的模型中将直接检查关节内炎症;此外， 将使用SPIM在光学透明膝关节上检查巨噬细胞（目的2）。第三，长期暴露于低 分级炎症可降低背根神经节（DRG）神经元的阈值。在这个提议中，膜片钳 记录将用于研究模拟关节损伤后的DRG致敏作用（目标3）。 此外，所有研究都将在OA相关疼痛和残疾的背景下收集，使用机械 超敏反应测试和步态分析以量化大鼠中的OA相关症状。最后，一个完善的 有效的OA治疗-适度运动-将在每个目标中进行评估，以了解运动如何改变 OA影响的膝关节的生理学，并导致OA相关症状的改善。总体而言，这 该方法将使用创新的定量方法，同时研究关节结构，炎症， 神经可塑性的方式，这是不可能在人类，使我们能够评估这些机制如何 有助于OA疼痛和残疾的连续性。

Project Summary A 2010 public awareness campaign entitled “Fight Arthritis Pain” promoted moving is the best medicine! While clinical studies overwhelmingly confirm exercise is an effective osteoarthritis (OA) treatment, patients often find this advice counterintuitive - “The solution for a painful joint is to use it more?” Part of this confusion is driven by chondrocentric definitions of OA, which imply that more cartilage damage will lead to more pain. However, OA is a `disease of the joint as an organ' with changes occurring throughout the joint. Moreover, factors that affect OA pain and disability occur both within and beyond the articular joint, including changes in joint structure, inflammation, and neuroplasticity. Understanding how these complex factors contribute to the patients' primary concerns - pain and disability - can help identify critical targets for OA therapy. Preclinical OA models should be a powerful tool to help researchers identify physiologic links between OA pathogenesis and symptomology, offering an opportunity to investigate facets of OA that cannot be easily explored in humans. Toward this goal, this proposal will use novel rodent gait analyses and measures of hind limb sensitivity to investigate how changes in joint structure, intra-articular inflammation, and dorsal root ganglia neuroplasticity relate to the development of OA-related pain and disability in rat models of post-traumatic knee OA. First, 3D measures of bony structures will be acquired in our models using a nanoCT, and 3D changes in cartilage and synovium will be assessed using selective plane illumination microscopy (SPIM) on optically- cleared knees (Aim 1). This aim will allow us to investigate relationships between complex 3D joint structures and OA-related pain and disability. Second, the missing link between OA pathogenesis and OA pain is often assumed to be inflammation, which can temporally cycle without major shifts in joint structure. In this proposal, intra-articular inflammation will be directly examined in our models; moreover, the distribution and quantity of macrophages will be examined using SPIM on optically cleared knees (Aim 2). Third, chronic exposure to low grade inflammation can lower the threshold of dorsal root ganglia (DRG) neurons. In this proposal, patch clamp recordings will be used to investigate DRG sensitization subsequent to simulated joint injuries (Aim 3). Additionally, all studies will be collected in the context of OA-related pain and disability, using mechanical hypersensitivity testing and gait analysis to quantify OA-related symptoms in the rat. Finally, a well-established and effective OA therapy - moderate exercise - will be evaluated in each aim to discern how exercise modifies the physiology of the OA-affected knee and leads to improvement in OA-related symptoms. Overall, this approach will use innovative, quantitative methods to simultaneously study joint structure, inflammation, and neuroplasticity in a manner that is not possible in humans, allowing us to assess how these mechanisms contribute to the continuum of OA pain and disability.