Exercise Induced Muscle Secreted Factors That Modify Osteoarthritis (OA) Severity

骨关节炎(OA)是一种常见的退行性疾病，是美国人的主要健康问题。 虽然众所周知，肌肉力量和运动可以调节OA的症状，但其机制 骨骼肌改变了骨性关节炎的发病机制，目前还没有完全阐明。传统的想法是肌肉 活动通过调节关节负荷和改变骨强度直接影响关节的生物力学， 减轻骨性关节炎的严重程度。然而，肌肉也会分泌具有旁分泌作用的因子。怎么会这样呢 影响关节的因素以及它们如何随着运动和肌肉病理变化而变化尚不清楚。 利用细胞培养研究，我们发现，在培养中锻炼的人类肌肉细胞产生分泌因子， 改变人类关节移植中与骨性关节炎严重程度相关的重要基因表达。然后，我们修改了一个 一种允许两只小鼠之间使用导管而不是标准异种共生进行循环交换的方法 技术。这种方法允许研究循环因素在一只动物中对OA严重程度的作用 在另一种动物中，虽然动物有不同的运动活动水平。我们的初步数据显示 在久坐动物中，当它的循环与一个人共享时，对OA严重程度重要的基因的下调 训练有素的动物。在这里，我们将开发识别这些因素的方法，并将描述体内的 策略来测试这些因子在啮齿动物中的作用。我们将实现以下目标： 根据我们的数据显示，来自锻炼肌肉的条件培养基会产生抑制因子 骨关节炎软骨移植中影响骨性关节炎严重程度的重要基因的表达，我们将进一步评估这些表达 不同运动方式和不同年龄肌肉细胞的旁分泌效应。识别不同的分泌物 蛋白质，我们将用质谱学的方法进行分泌组分析。 使用我们改进的基于导管的方法交换循环血液，允许动物共享 在进行不同的体力活动养生的同时，我们将确定如何持续时间 运动、换血次数和血浆或细胞成分改变了骨性关节炎的表型 与外科关节损伤有关。运动调节差异最大的蛋白质的表达 在第一个目的中确定的将使用ELISA法在运动小鼠和安静小鼠的血清之间进行比较。 识别出的蛋白质可能是药理学上的靶点，因此，我们的数据可能会识别一种治疗方法 可以用来减轻骨性关节炎严重程度的方法。此外，这项工作将定义具体的 运动生化效应对骨性关节炎严重程度的影响。

Osteoarthritis (OA) is a common degenerative process that is a major health problem in the US population. While it is known that muscle strength and exercise can modulate OA symptoms, the mechanism by which skeletal muscle alters OA pathogenesis is only partly elucidated. The conventional thought is that muscle activity directly affects the joint biomechanically by modulating joint loading and altering bone strength, attenuating OA severity. However, muscle also secretes factors that can have paracrine effects. How such factors affect the joint and how they change with exercise and in muscle pathologies is not known. Using cell culture studies, we found that human muscle cells exercised in culture produce secreted factors that alter the expression of important genes in OA severity in human articular explants. We then modified an approach that allows circulatory exchange between two mice using catheters rather than a standard parabiosis technique. This approach allows the study of the role of circulating factors in one animal on the severity of OA in another animal, while the animals have different exercise activity levels. Our preliminary data shows the downregulation of genes important in OA severity in a sedentary animal when its circulation is shared with an exercised animal. Here we will develop approaches to identify these factors and will characterize an in-vivo strategy to test the function of such factors in rodents. We will undertake the following aims: Building on our data showing that conditioned media from exercised muscle produces factors that inhibit expression of genes important in OA severity in osteoarthritic cartilage explants, we will further evaluate these paracrine effects for different exercise regimes and ages of the muscle cells. To identify differentially secreted proteins, we will use mass spectroscopy secretome analysis. Using our modified catheters based approach to exchange circulating blood, allowing animals to share a circulation while undertaking different physical activity regimens, we will determine how the duration of exercise, number of blood exchange procedures, and plasma or cell fractions alter the OA phenotype associated with a surgical joint injury. Expression of the most differentially regulated proteins by exercise identified in the first aim will be compared between the serum from exercised and quiescent mice using ELISA. Identified proteins could be targeted pharmacologically and as such, our data may identify a therapeutic approach that could be used to attenuate the severity of OA. Furthermore, this work will define the specific contribution of biochemical effects of exercise on OA severity.