Mechanism of hyaluronan depolymerization due to Reactive oxygen species (ROS) produced by synoviocytes cultured in hypoxia, resulting synovial proliferation.

骨关节炎的病因学被认为涉及软骨退变和滑膜增殖。我们先前已经证明，活性氧物种(ROS)参与了软骨的降解。据报道，关节炎患者关节滑液中的主要大分子透明质酸(NA)体积变小，使其具有粘性。本研究的目的是确定由于机械变形对软骨细胞造成的HA分子量范围的改变，以及ROS在这一作用中的参与。次黄嘌呤被黄嘌呤氧化酶氧化生成ROS。使用真空操作仪(FX-3000)加载循环拉伸。用夹心酶结合法测定透明质酸水平。分别用水溶性四唑盐和化学发光探针法测定超氧化物歧化酶(SOD)活性、催化超氧阴离子歧化为过氧化氢(H_2O_2)和ROS。ROS解聚了HA分子。循环拉伸使HA解聚，并诱导ROS。超氧化物歧化不仅抑制了ROS的诱导，而且还抑制了机械应力引起的HA解聚。这些数据表明，ROS在机械应力诱导的HA解聚中起着重要作用。解聚的HA可刺激滑膜增殖，激活滑膜炎症。

Etiology of osteoarthritis is supposed to involve cartilage degeneration and synovial proliferation. We have previously demonstrated that reactive oxygen species (ROS) are involved in cartilage degradation. Decreased size of hyaluronan (NA), the major macromolecule in synovial fluid, to which it imparts viscosity, is reported in patients with arthritis. The purpose of this study was to determine the alteration in the molecular weight range of HA as a result mechanical deformation loaded on the chondrocytes, as well as the involvement of ROS in this action. ROS were generated via the oxidation of hypoxanthine by xanthine oxidase. Cyclic tensile stretch was loaded using a vacuum-operated instrument (FX-3000). Levels of HA were measured using a sandwich enzyme-binding assay. Superoxide dismutase (SOD) activity, catalysing the dismutation of superoxide anion into hydrogen peroxide, and ROS were measured using water-soluble tetrazolium and a chemiluminescent probe, respectively. ROS depolymerized HA molecules. Cyclic tensile strech depolymerized HA and induced ROS. SOD inhibited not only ROS induction but also HA depolymerization caused by the mechanical stress. These data suggest that ROS play an important role in mechanical stress-induced HA depolymerization. Depolymerized HA may stimulate synovial proliferation and activate synovial inflammation.