Entheses, which are tendon-to-bone attachment sites in the musculoskeletal system, play important roles in optimizing the mechanical stress and force transmitted from the muscle to the bone. Sports-related enthesopathy shows pathological features, including hyperplasia of the fibrocartilage (FC) region in the enthesis. The amount of exercise and type of muscle contraction during movement is involved in the pathogenesis of sports-related enthesopathy; however, the details of this condition are unclear. Here we examined the molecular pathways involved in the morphological changes of the muscle–tendon–enthesis complex and enthesis FC region in the supraspinatus muscle enthesis of mice under different exercise conditions. Following intervention, morphological changes in the muscle–tendon–enthesis complex were initiated in the eccentric contraction-dominant exercise group at 2 weeks, with activation of the transforming growth factor-β (TGFβ) superfamily pathway predicted by proteome and ingenuity pathway analyses. Histological and molecular biological analyses confirmed the activation of the TGFβ/bone morphogenetic protein (BMP)-Smad pathway. The concentric contraction-dominant exercise group showed no change in the morphology of the muscle–tendon–enthesis complex or activation of the TGFβ/BMP-Smad pathway, despite overuse exercise. Statement of Clinical Significance: These results suggest that eccentric contraction-dominant exercise induces sports-related enthesopathy-like morphological changes in the early stages as well as molecular biological changes, mainly in the transforming growth factor-β superfamily pathway in enthesis.

中文翻译：

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偏心收缩主导运动导致附着点分子生物学变化和附着点病样形态学变化

附着点是肌肉骨骼系统中肌腱与骨骼的附着部位，在优化从肌肉传递到骨骼的机械应力和力方面起着重要作用。运动相关的附着点病变表现出病理特征，包括附着点中纤维软骨 (FC) 区域的增生。运动过程中的运动量和肌肉收缩类型与运动相关的肌腱端病的发病机制有关；但是，这种情况的细节尚不清楚。在这里，我们检查了不同运动条件下小鼠冈上肌肌腱端肌肉-肌腱-附着点复合体和附着点 FC 区形态变化所涉及的分子通路。干预后，肌肉-肌腱-附着点复合体的形态变化在 2 周时在偏心收缩为主的运动组中开始，蛋白质组和独创性途径分析预测转化生长因子-β (TGFβ) 超家族途径被激活。组织学和分子生物学分析证实了 TGFβ/骨形态发生蛋白 (BMP)-Smad 通路的激活。尽管运动过度，但以向心收缩为主的运动组显示肌肉-肌腱-附着点复合体的形态或 TGFβ/BMP-Smad 通路的激活没有变化。临床意义声明：这些结果表明，以离心收缩为主的运动会在早期诱发运动相关的附着点病样形态学变化以及分子生物学变化，