Relić Biserka, Bentires-Alj Mohamed, Ribbens Clio, Franchimont Nathalie, Guerne Pierre-André, Benoît Valerie, Merville Marie-Paule, Bours Vincent, Malaise Michel G
Center for Cellular and Molecular Therapy, University of Liège, Belgium.
Lab Invest. 2002 Dec;82(12):1661-72. doi: 10.1097/01.lab.0000041714.05322.c0.
TNF-alpha plays a key role in rheumatoid arthritis, but its effect on chondrocyte survival is still conflicting. In the present study, we tested how TNF-alpha influences chondrocyte survival in response to nitric oxide (NO)-related apoptotic signals, which are abundant during rheumatoid arthritis. Human primary articular chondrocytes or cartilage explants were pretreated with TNF-alpha for 24 hours and then treated with the proapoptotic NO donor sodium-nitro-prusside (SNP) for an additional 24 hours. TNF-alpha pretreatment markedly protected chondrocytes from SNP-induced cell death. Preincubation of chondrocytes with TNF-alpha inhibited both SNP-induced high-molecular weight DNA fragmentation and annexin V-FITC binding. Of interest, TNF-alpha induced persistent nuclear factor-kappaB (NF-kappaB)-DNA binding activity even in the presence of SNP, mirroring apoptosis protection effects. Both the TNF-alpha antiapoptotic effect and NF-kappaB-DNA binding activity were significantly inhibited by NF-kappaB inhibitors, Bay 11-7085, MG-132, and adenovirus-expressing mutated IkappaB-alpha. Phosphatidylinositol-3 kinase inhibitor LY 294002 also markedly inhibited the antiapoptotic effect of TNF-alpha. In primary chondrocytes, TNF-alpha induced expression of the antiapoptotic protein Cox-2, which persisted in the presence of SNP, and a specific Cox-2 inhibitor significantly blocked the TNF-alpha protective effect. We therefore conclude that TNF-alpha-mediated protection of chondrocytes from NO-induced apoptosis acts through NF-kappaB and requires Cox-2 activity.
肿瘤坏死因子-α（TNF-α）在类风湿性关节炎中起关键作用，但其对软骨细胞存活的影响仍存在争议。在本研究中，我们测试了TNF-α如何影响软骨细胞对类风湿性关节炎期间大量存在的一氧化氮（NO）相关凋亡信号的存活反应。将人原代关节软骨细胞或软骨外植体用TNF-α预处理24小时，然后再用促凋亡的NO供体硝普钠（SNP）处理24小时。TNF-α预处理显著保护软骨细胞免受SNP诱导的细胞死亡。软骨细胞与TNF-α预孵育可抑制SNP诱导的高分子量DNA片段化和膜联蛋白V-FITC结合。有趣的是，即使在存在SNP的情况下，TNF-α仍能诱导持续的核因子-κB（NF-κB）-DNA结合活性，这反映了其凋亡保护作用。NF-κB抑制剂Bay 11-7085、MG-132和表达突变型IκB-α的腺病毒均显著抑制了TNF-α的抗凋亡作用和NF-κB-DNA结合活性。磷脂酰肌醇-3激酶抑制剂LY 294002也显著抑制了TNF-α的抗凋亡作用。在原代软骨细胞中，TNF-α诱导抗凋亡蛋白Cox-2的表达，在存在SNP的情况下该表达持续存在，并且一种特异性Cox-2抑制剂显著阻断了TNF-α的保护作用。因此，我们得出结论，TNF-α介导的软骨细胞免受NO诱导凋亡的保护作用是通过NF-κB起作用的，并且需要Cox-2活性。
