Homandberg G A, Wen C, Hui F
Department of Biochemistry, Rush Medical College at Rush-Presbyterian-St Luke's Medical Center, Chicago, Illinois 60612-3864, USA.
Osteoarthritis Cartilage. 1998 Jul;6(4):231-44. doi: 10.1053/joca.1998.0116.
To investigate whether fibronectin fragments (Fn-fs), shown to damage cultured cartilage, can be found in cartilage from patients with osteoarthritis (OA) or rheumatoid arthritis, or can be generated from fibronectin (Fn) within synovial fluids or from Fn in the matrix of cultured cartilage. To also determine whether cartilage or synovial fluid Fn-fs are active and, thus, could contribute to cartilage damage in vivo.
Fn-fs were immunochemically identified in cartilage extracts from patients with OA or rheumatoid arthritis or in bovine cartilage cultured with IL-1 alpha or in bovine synovial fluids treated with stromelysin-1 (MMP-3). The effect of removal of Fn-fs from OA synovial fluids was tested by passing fluids over an anti-Fn column and adding the resultant fluids to bovine cartilage cultures to measure proteoglycan (PG) degradation. Gelatin-Sepharose purified Fns from bovine plasma, synovial fluid or cartilage were digested with MMP-3 and the Fn-fs tested for degradation of PG in cultured cartilage.
Extracts of cartilage from patients with rheumatoid arthritis or with OA contained a range of Fn-fs. Removal of Fn-fs from OA synovial fluids significantly reduced the resultant damage when the fluids were added to cultured cartilage. Addition of IL-1 alpha to cultured cartilage or of MMP-3 to synovial fluids enhanced generation of Fn-fs. Fn-fs, whether derived from bovine plasma or synovial fluid or cartilage Fns, damaged cartilage.
These data demonstrate that although Fn-fs could be generated in vivo within synovial fluids and Fn-fs found in OA synovial fluid may contribute to cartilage damage in vivo, Fn-fs could also be generated within cartilage and amplify cartilage damage. Thus, Fn-fs may be both autocrine and paracrine regulators of cartilage metabolism.
研究在体外实验中显示可损伤培养软骨的纤连蛋白片段（Fn-fs）是否存在于骨关节炎（OA）或类风湿关节炎患者的软骨中，或者是否可由滑液中的纤连蛋白（Fn）或培养软骨基质中的Fn产生。同时确定软骨或滑液中的Fn-fs是否具有活性，进而是否可能在体内导致软骨损伤。
采用免疫化学方法在OA或类风湿关节炎患者的软骨提取物中、用白细胞介素-1α（IL-1α）培养的牛软骨中或用基质溶解素-1（基质金属蛋白酶-3，MMP-3）处理的牛滑液中鉴定Fn-fs。通过将OA滑液通过抗Fn柱，然后将所得液体添加到牛软骨培养物中以测量蛋白聚糖（PG）降解，来测试从OA滑液中去除Fn-fs的效果。用MMP-3消化从牛血浆、滑液或软骨中经明胶-琼脂糖纯化的Fn，并测试Fn-fs对培养软骨中PG的降解作用。
类风湿关节炎或OA患者的软骨提取物中含有一系列Fn-fs。当将OA滑液添加到培养软骨中时，从OA滑液中去除Fn-fs可显著减少由此产生的损伤。向培养软骨中添加IL-1α或向滑液中添加MMP-3可增强Fn-fs的产生。无论源自牛血浆、滑液还是软骨Fn的Fn-fs，均可损伤软骨。
这些数据表明，尽管Fn-fs可在滑液中体内产生，且在OA滑液中发现的Fn-fs可能在体内导致软骨损伤，但Fn-fs也可在软骨内产生并加剧软骨损伤。因此，Fn-fs可能是软骨代谢的自分泌和旁分泌调节因子。
