Biomechanical Regulation of Oxidative Homeostasis in Articular Cartilage

描述（由申请人提供）：骨关节炎（OA）是一种使人衰弱和退行性关节疾病，影响美国超过25%的成年人。机械负荷的改变，如肥胖或关节损伤，被认为是OA的起始因素。然而，一些形式的负荷，如物理治疗和运动，被用于治疗OA。机械负荷将软骨代谢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净氧化状态来调节关节软骨平衡的机制。我假设循环机械负荷的持续时间和强度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介质。我将用牛关节软骨外植体模型和体外动态组织压缩系统来验证这一假设。我将确定一系列生理和超生理循环机械负荷对软骨基质稳态和软骨细胞的净氧化、能量和炎症状态的影响。在确定了一组引起适应性（即，体内平衡）和不适应（即，氧化修饰）反应的加载条件之后，我将确定这些加载条件对促氧化和抗氧化转录和蛋白质组反应以及总细胞抗氧化功能的影响。最后，为了更好地理解参与抗氧化反应的信号通路，我将使用靶向抗氧化预处理来确定特定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。拟议的研究将检查软骨对促氧化剂的生物力学预处理如何产生代偿性抗氧化反应以维持氧化稳态。它还将描述抗氧化剂如何用于预防或治疗OA，可能会干扰生物力学负荷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稳态的生物力学基础上的训练。导师的实验室和OMRF的自由基生物学和衰老项目是接受这一领域培训的理想场所。我将得到一大批在肌肉骨骼生物力学、氧化反应途径、蛋白质组学和遗传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，将新概念应用于肌肉骨骼结构的功能性组织工程，这些结构可以在植入损伤的促炎症和促氧化部位后提高细胞存活率和组织功能。

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.