肿瘤坏死因子受体p55和p75在骨关节炎软骨细胞的表达及意义

The expression of tumor necrosis factor-α receptor on chondrocytes isolated from patients with osteoarthritis

目的探讨肿瘤坏死因子（TNF）-α受体（TNFR）p55和p75在骨关节炎（OA）患者软骨细胞中的表达情况，及在介导TNF吨诱导软骨细胞产生基质金属蛋白酶-3（MMP-3）中的作用。方法分离于5例OA患者和2名正常人的软骨细胞经体外培养后。采用间接免疫荧光法、反转录聚合酶链反应（RT-PCR）和流式细胞分析技术检测p55和p75TNFR在软骨细胞的表达；MMP-3的测定采用酶联免疫吸附试验（ELISA）。结果p55和p75TNFRmRNA的表达，以及它们在细胞表面的表达在OA软骨细胞均高于正常软骨细胞：在OA软骨细胞，p75TNFR的表达高于p55TNFR，但用抗p55中和抗体可以明显降低TNF-α诱导的软骨细胞产生MMP-3，而抗p75中和抗体则无此作用。结论TNFR在OA软骨细胞表达增高。表明TNF／TNFR系统在OA的病理过程中发挥作用，而抗p55抗体对TNF-α诱导MMP-3产生的阻断作用。提示TNF-α主要通过p55介导软骨破坏。

Objective To investigate the presence and level of expression of tumor necrosis factor receptors （TNFR） in normal and ostenarthritis （OA） human chondrocytes, and to determine which receptor isotype mediates the biological response of these cells to TNF-α. Methods The expression of p55 TNFR and p75 TNFR on chondrocytes was analyzed on mRNA and protein levels by indirect immunofluorescence（IIF）, reverse transcription polymerase chain reaction （RT-PCR） technique and flow cytometric analysis. Matrix metalloproteinase-3 （MMP-3） was measured after incubation with TNF-α in the presence or absence of receptor specific blocking antibodies. Results Both p55 and p75 TNFR mRNA were expressed constitutively on human articular ehondrocytes, with increased expression of these receptors in OA chondrocytes. Moreover, p75 TNFR expression was higher than p55 TNFR in OA chondrocytes. These results were consistent with the protein data obtained by flow cytometric analysis. The p55 TNFR was found to be the major receptor species responsible for ligand binding activity, since a specific anti-p55 TNFR blocking antibody inhibited TNF-α-stimulated MMP-3 production. Conclusion The increased expression of TNFR on OA chondrocytes suggests a role of TNF-α/ TNFR system in the degradation processes of articular cartilage in OA. The inhibition of TNF-α-induced MMP-3 production by a specific anti-p55 TNFR blocking antibody, indicates that p55 TNFR is the major receptor isofor mediating the biological response of chondrocytes to TNF-α.