Pichika R, Homandberg G A
Department of Biochemistry, Rush Medical College at Rush-Presbyterian-St. Luke's Medical Center, 1653 West Congress Parkway, Chicago, IL 60612-3864, USA.
Inflamm Res. 2004 Aug;53(8):405-12. doi: 10.1007/s00011-004-1279-8. Epub 2004 Aug 10.
To determine whether fibronectin fragments (Fn-f) upregulate nitric oxide (NO) and inducible NO synthetase (iNOS) levels in explants and whether iNOS inhibitors block Fn-f mediated cartilage damage or promote repair.
Bovine cartilage explants were studied.
Explants were cultured with Fn-f and involvement of NO pathway investigated.
Induction of iNOS was tested by RT-PCR. Upregulation of iNOS protein was visualized by Western blotting. Proteoglycan (PG) content of cartilage treated with iNOS inhibitors was tested by dye binding assays of cartilage digests.
Fn-fs elevated NO release in explants and upregulated iNOS protein and mRNA while native Fn had only weak activity. Three different iNOS inhibitors blocked Fn-f mediated PG depletion from explants and facilitated restoration of PG in pre-damaged cartilage.
The Fn-f cartilage damaging pathway involves upregulation of iNOS. Interestingly, iNOS inhibitors not only blocked damage but repaired damaged cartilage. This may be the first report of reparative activities of iNOS inhibitors.
确定纤连蛋白片段（Fn-f）是否上调外植体中一氧化氮（NO）和诱导型一氧化氮合酶（iNOS）的水平，以及iNOS抑制剂是否能阻断Fn-f介导的软骨损伤或促进修复。
研究牛软骨外植体。
将外植体与Fn-f一起培养，并研究NO途径的参与情况。
通过逆转录聚合酶链反应（RT-PCR）检测iNOS的诱导情况。通过蛋白质印迹法观察iNOS蛋白的上调情况。通过对软骨消化物进行染料结合测定来检测用iNOS抑制剂处理的软骨中蛋白聚糖（PG）的含量。
Fn-fs在外植体中提高了NO释放，并上调了iNOS蛋白和信使核糖核酸（mRNA），而天然Fn只有微弱的活性。三种不同的iNOS抑制剂阻断了Fn-f介导的外植体中PG的消耗，并促进了受损前软骨中PG的恢复。
Fn-f软骨损伤途径涉及iNOS的上调。有趣的是，iNOS抑制剂不仅阻断了损伤，还修复了受损软骨。这可能是关于iNOS抑制剂修复活性的首次报道。
