Piezo2-mediated neuroplasticity in osteoarthritis

项目摘要 尽管骨关节炎（OA）引起的慢性疼痛和残疾的患病率很高，但目前还没有 有效的治疗方法可以阻止进展或长期管理疼痛。患者经常报告停止 他们发现以前喜欢的活动或避免日常生活所需的活动， OA疼痛的机械敏感性。我们对OA的理解已经从一种磨损的心态演变为一种 涉及免疫和神经系统的复杂疾病状态，确实存在免疫增强， 细胞和炎症介质。在小鼠中， 膝神经支配背根神经节（DRG）中巨噬细胞增加;预防巨噬细胞 通过巨噬细胞耗竭或伤害感受器沉默的募集，已经显示出减少OA疼痛的希望， 行为。有趣的是，Piezo 2是一种机械激活的离子通道， 在两种关节疼痛模型中证明疼痛行为减少，并防止关节肿胀。 在OA的动物模型中，有证据表明神经可塑性改变和致敏作用减弱 通过抗神经生长因子（NGF）治疗和通过抑制Piezo 2，表明 机械刺激和炎症的神经可塑性。卸载已被证明是沉默的机械 信号转导，减少膝关节中有害蛋白酶的表达， 与NSAID联合治疗相比，然而，没有研究评估卸载对 疼痛相关的神经可塑性我们相信机械信号是巨噬细胞 招募和致敏OA，特别是通过Piezo 2。因此，我们的中心假设是： 机械刺激对于关节神经可塑性和炎性机械致敏是必需的， 抑制机械传导，我们将有效地减少免疫细胞的招募， 从而带来痛苦目的1将评估通过Piezo 2CKO抑制机械刺激的有效性， 减少免疫细胞向膝关节和DRG的募集。目标2将梳理除了机械的相互作用 负荷和炎症在疼痛相关的神经可塑性的机械卸载小鼠，以确定是否 在实验性疼痛条件下发生改变的神经可塑性。这个项目将为我提供机会 学习新技能（流式细胞术、体内钙成像、测序）并开发新技术。我会 也有机会提高实现我的职业目标所需的技能，即实验设计， 科学交流，批判性思维等。完成拟议的项目将增加我们的 理解疼痛发展中机械信息和免疫细胞动力学的相互作用， 打开选择性治疗干预的大门。

Project Summary Despite the high prevalence of chronic pain and disability due to osteoarthritis (OA), there currently is no effective treatment available to stop progression or manage pain long term. Patients often report ceasing activities they found previously enjoyable or avoiding activities required for daily living due to the highly mechanosensitive nature of OA pain. Our understanding of OA has evolved from a wear and tear mindset to a complex disease state involving the immune and neurological systems, indeed there is an increase in immune cells and inflammatory mediators within the synovial fluid of humans and mice. Further in mice we see an increase in macrophages in knee innervating dorsal root ganglia (DRG); prevention of macrophage recruitment, by macrophage depletion or nociceptor silencing, has shown promise in reducing OA pain like behaviors. Interestingly, mice with Piezo2, a mechanically activated ion channel, knocked out from nociceptors demonstrate a reduction in pain behavior in two models of joint pain and are protected from joint swelling. Within animal modeling of OA there is evidence of altered neuroplasticity and sensitization that is attenuated by anti-nerve growth factor (NGF) therapy and through inhibition of Piezo2 suggesting an interplay between mechanical stimuli and inflammation in neuroplasticity. Unloading has been shown to silence mechanical signal transduction, decrease the expression of harmful proteases in the knee and is more effective in reducing synovitis than combination treatment with NSAIDs. However, no study has assessed the effect of unloading on pain associated neuroplasticity. We believe that mechanical signaling is a key player in macrophage recruitment and sensitization in OA, specifically through Piezo2. Therefore, our central hypothesis is: mechanical stimuli are necessary for joint neuroplasticity and inflammatory mechanical sensitization and by inhibiting mechanotransduction we will effectively reduce immune cell recruitment, abhorrent neuroplasticity and thus pain. Aim 1 will assess the effectiveness of inhibition of mechanical stimuli through Piezo2CKO in reducing immune cell recruitment to the knee and DRG. Aim 2 will tease apart the interplay of mechanical loading and inflammation in pain associated neuroplasticity by mechanically unloading mice to determine if altered neuroplasticity occurs under experimental pain conditions. This project will provide me the opportunity to learn new skills (flow cytometry, in vivo calcium imaging, sequencing) and develop novel techniques. I will also be given the opportunity to enhance skillsets required to achieve my career goals i.e. experimental design, scientific communication, critical thinking etc. Completion of the proposed project will increase our understanding of the interplay of mechanical information and immune cell dynamics in pain development and open the doors to routes of selective therapeutic intervention.