Biomechanical Regulation of Oxidative Homeostasis in Articular Cartilage

描述(申请人提供)：骨关节炎(OA)是一种衰弱和退行性关节疾病，影响超过25%的美国成年人口。改变的机械负荷，如肥胖或关节损伤，被认为是骨关节炎的始动因素。然而，某些形式的负荷，如物理治疗和锻炼，可用于治疗骨性关节炎。机械负荷将软骨代谢的动态平衡从合成代谢转变为分解代谢的机制尚不清楚。本研究的目的是阐明生物力学信号通过改变细胞抗氧化防御系统和网状氧化状态来调节关节软骨稳态的机制。我假设，循环机械负荷的持续时间和大小是决定细胞净氧化和能量状态的促氧化和抗氧化反应之间平衡的关键中介。我将使用带有体外动态组织压迫系统的牛关节软骨移植模型来验证这一假设。我将确定一系列生理性到超生理性的周期性机械负荷对软骨基质动态平衡和软骨细胞的净氧化、能量和炎症状态的影响。在确定了一组可引发适应性(即，稳态)与非适应性(即，氧化修饰)反应的负荷条件后，我将确定这些负荷条件对促氧化和抗氧化剂转录和蛋白质组反应以及细胞总抗氧化功能的影响。最后，为了更好地了解参与抗氧化反应的信号通路，我将使用有针对性的抗氧化预处理来确定特定的促氧化剂在改变生物力学诱导的促氧化和抗氧化功能中的作用。这项拟议的研究将检验软骨对促氧化剂的生物力学预适应如何产生代偿性抗氧化反应以维持氧化动态平衡。它还将描述用于预防或治疗骨性关节炎的抗氧化剂的使用如何干扰参与对生物力学负荷的正常适应性反应的信号通路。这个奖项将支持我在细胞代谢和氧化动态平衡的生物力学基础上的培训。导师的实验室和OMRF的自由基生物学和老龄化计划是接受这一领域培训的理想环境。我将得到一大批在肌肉骨骼生物力学、氧化反应途径、蛋白质组学和基因分析方面具有专业知识的研究人员的支持。在未来的研究中，我计划利用通过该奖项获得的专业知识和技术，将新的概念应用于肌肉骨骼结构的功能组织工程，这种结构可以在植入促炎和促氧化损伤部位后改善细胞存活和组织功能。 公共卫生相关性：该项目将调查生物力学诱导的氧化和抗氧化过程在关节软骨正常内稳态中的作用。通过确定机械因素在刺激软骨组织中产生的内源性抗氧化剂中的作用，可能为预防或治疗骨性关节炎提供新的见解。

DESCRIPTION (provided by applicant): Osteoarthritis (OA) is a debilitating and degenerative joint disease that affects more than 25% of the adult population in the United States. Altered mechanical loads, such as those due to obesity or joint injury, are implicated as initiating factors for OA. Some forms of loading, however, such as physical therapy and exercise, are used to treat OA. The mechanisms by which mechanical loading shifts the homeostasis of cartilage metabolism from anabolic to catabolic is not known. The goal of the proposed study is to elucidate the mechanisms by which biomechanical signals regulate articular cartilage homoeostasis via changes in the cellular anti-oxidant defense system and the net oxidative state. I hypothesize that the duration and magnitude of cyclic mechanical loading are critical mediators of the balance between pro- and anti-oxidant responses that determine the net oxidative and energetic state of the cell. I will test this hypothesis using a bovine articular cartilage explant model with an in vitro dynamic tissue compression system. I will determine the effect of a range of physiologic to hyper-physiologic cyclic mechanical loads on cartilage matrix homeostasis and the net oxidative, energetic, and inflammatory state of chondrocytes. Having identified a set of loading conditions that elicit an adaptable (i.e., homeostatic) versus a maladaptive (i.e., oxidative modification) response, I will then determine the effect of these loading conditions on pro- and anti-oxidant transcriptional and proteomic responses and the total cellular anti-oxidant function. Finally, to better understand the signaling pathways involved in the anti-oxidant response, I will use targeted anti-oxidant pre-treatments to identify the role of specific pro-oxidants in altering biomechanically-induced pro- and anti-oxidant functions. The proposed research will examine how biomechanical pre-conditioning of cartilage to pro-oxidants may produce compensatory anti-oxidant responses to maintain oxidative homeostasis. It will also delineate how the use of anti-oxidants, for the prevention or treatment of OA, may interfere with signaling pathways involved in normal adaptive responses to biomechanical loading. This award will support my training in the biomechanical basis of cellular metabolic and oxidative homeostasis. The mentor's lab and the Free Radical Biology and Aging program at OMRF is the ideal setting for receiving training in this area. I will receive support from a critical mass of investigators with expertise in musculoskeletal biomechanics, oxidative response pathways, and proteomic and genetic analysis. In future studies, I plan to use the expertise and techniques acquired through this award to apply new concepts to functional tissue engineering of musculoskeletal constructs that could improve cell survival and tissue function following implantation into pro-inflammatory and pro-oxidative sites of injury. PUBLIC HEALTH RELEVANCE: This project will investigate the role of biomechanically-induced oxidative and anti-oxidative processes in the normal homeostasis of articular cartilage. It may provide new insights into the prevention or treatment of osteoarthritis by identifying the role of mechanical factors in stimulating endogenous anti-oxidant processed in cartilage tissue.