The Multiscale Role of Piezo Channels in Obesity-Associated Cartilage Damage

项目总结 骨关节炎(OA)是一种使滑膜关节衰弱的疾病，是疼痛和残疾的主要原因。 全世界。OA影响着3000多万美国人，但目前还没有治疗疾病的药物。肥胖是一个主要问题 OA的危险因素；然而，很难将低水平的系统性炎症的作用与 随着身体质量的增加而改变关节负荷的影响。而软骨需要加载以维持组织 体内平衡，先前的研究表明，由于体重增加而导致的异常负荷可能解释了 为什么与健康体重相比，肥胖者的软骨损伤率更高 个人。然而，最近的许多研究表明，体重增加本身并不能解释骨性关节炎 在人类和动物模型中的损害，脂肪因子，来自身体脂肪的炎症介质，发挥着 在骨性关节炎发病机制中起重要作用。此外，Guilak实验室之前的研究强调了协同效应 机械敏感离子通道Piezo1和Piezo2在软骨健康和维护中的重要性： 肥胖和骨质疏松症相关炎症介质白介素1α(IL-1α)调节和敏化Piezo 通道功能。因此，这项提议调查了细胞因子/脂肪因子信号是否是 压电通道对机械力高度敏感，最终导致软骨细胞死亡增加。 这项提议的目标是直接调查肥胖相关炎症和肥胖之间的相互作用 软骨细胞的机械敏感性。机械感觉改变在发病机制中作用的研究 对肥胖的骨性关节炎的研究将导致针对这些途径的最终目标，以开发新的治疗方法 接近了。具体目标1侧重于确定肥胖相关的炎症条件是否会改变Piezo 在软骨中的表达，如果这种表达增加转化为软骨细胞对 机械载荷。这项研究集中在肥胖的关键调节失调脂肪因子：IL-1α、瘦素、肿瘤坏死 肿瘤坏死因子-α和白介素6。SPICAL AIM 2使用的是先前在 实验室研究软骨细胞特异性Piezo1和/或Piezo2离子通道的丢失是否对软骨具有保护作用 肥胖和关节损伤的体内模型中的损伤。具体地说，老鼠将被喂以高脂肪饮食(60%脂肪)和 接受内侧半月板失稳(DMM)手术，已知会引发创伤后骨性关节炎。 这两个目标共同战略性地开发原子力显微镜(AFM)和钙(Ca+)成像技术 体内软骨完整性评估，以补充使用转基因小鼠在一个模型 HFD合并DMM损伤。这项研究的结果将有助于确定 肥胖影响软骨健康，最终导致骨关节炎疾病修饰药物的开发，这可能 更广泛地应用于受压电离子通道机械感觉改变影响的其他组织。

PROJECT SUMMARY Osteoarthritis (OA) is a debilitating disease of the synovial joints and is the leading cause of pain and disability worldwide. OA affects over 30 million Americans, but there are no disease modifying drugs. Obesity is a major risk factor for OA; however, it has been difficult to disentangle the role of low-level systemic inflammation from the effects of altered joint loading with increased body mass. While cartilage requires loading to maintain tissue homeostasis, previous studies have suggested that abnormal loading due to increased body mass may explain why individuals with obesity experience cartilage damage at elevated rates when compared to healthy weight individuals. However, many recent studies demonstrate that increased body mass alone does not explain OA damage in human and animal models, and that adipokines, inflammatory mediators from body fat, play an important role in OA pathogenesis. Additionally, previous studies from the Guilak lab highlight the synergistic importance of the mechanosensitive ion channels Piezo1 and Piezo2 in cartilage health and maintenance: obesity and an OA-relevant inflammatory mediator, interleukin 1 alpha (IL-1α), modulates and sensitizes Piezo channel function. As such, this proposal investigates if cytokine/adipokine signaling is the mechanism by which Piezo channels become hypersensitized to mechanical force, ultimately leading to increased chondrocyte death. The goal of this proposal is to directly investigate the interaction between obesity-associated inflammation and the mechanosensitivity of chondrocytes. This study on the role of altered mechanosensation in the pathogenesis of OA with obesity will lead to the ultimate goal of targeting these pathways to develop novel therapeutic approaches. Specific Aim 1 focuses on determining if obesity-associated inflammatory conditions alter Piezo expression in cartilage and if this increased expression translates to increased chondrocyte sensitivity to mechanical loads. This study hones in on key dysregulated adipokines with obesity: IL-1α, Leptin, tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6). Specific Aim 2 uses transgenic mice previously developed in the lab to investigate if the loss of chondrocyte-specific Piezo1 and/or Piezo2 ion channels protects against cartilage damage in an in vivo model of obesity and joint injury. Specifically, mice will be fed a high-fat diet (60% fat) and subjected to a destabilization of the medial meniscus (DMM) surgery, known to evoke post-traumatic OA. Together, both aims strategically develop atomic force microscopy (AFM) and calcium (Ca2+) imaging techniques with in vivo assessments of cartilage integrity to complement the use of genetically-modified mice in a model of HFD superimposed with DMM injury. The results from this study will help identify the mechanisms by which obesity affects cartilage health, ultimately leading to the development of OA disease modifying drugs, that may be more broadly applied to other tissues affected by altered mechanosensation of Piezo ion channels.