Functional analyses for transmembrane TNF-alpha

肿瘤坏死因子-α拮抗剂因其在活动性慢性炎症性疾病中的显著临床疗效而备受关注。在类风湿关节炎中，英夫利昔单抗、人源化抗肿瘤坏死因子α抗体和依那西普均有效，而在克罗恩病中，只有英夫利昔单抗和阿达莫单抗能诱导临床缓解。由于这种不同的临床疗效可能是由生物效应引起的，而不是仅仅中和可溶性的肿瘤坏死因子-α，所以我们在这里研究了通过跨膜肿瘤坏死因子-α的反向信号。在表达mtnf的Jurkat T细胞检测系统中，用基因芯片分析英夫利昔单抗诱导的mtnf，通过定点突变将mtnf第2、5和27位的胞质丝氨酸残基依次替换为丙氨酸。英夫利昔单抗诱导的细胞凋亡和细胞周期停滞完全被这三个细胞质丝氨酸残基取代。在本研究中，我们揭示了英夫利昔单抗和依那西普诱导的新的生物学效应是通过mtnf的反向信号介导的，这可能解释了这两种抗肿瘤坏死因子-α的不同临床疗效。探员们。我们还阐明了胞质丝氨酸残基在mtnf信号转导中的关键作用。

TNF-alpha antagonists are the center of attention for their dramatic clinical efficacy in active chronic inflammatory diseases. In rheumatoid arthritis, both infliximab (chimeric anti-TNF-alpha antibody), adalimumab (humanized anti-TNF-alpha antibody) and etanercept (p75 TNF-alpha receptor fusion protein) are highly effective, while in Crohn's disease, only infliximab and adalimumab can induce clinical remission. As the differential clinical efficacy was likely to be caused by biological effects other than mere neutralization of soluble TNF-alpha, we here investigated reverse signaling through transmembrane TNF-alpha. mTNF induced by infliximab was analysed by cDNA array in the assay system using mTNF-expressing Jurkat T cells.Cytoplasmic serine residues at positions 2, 5 and 27 of mTNF were sequentially substituted to alanine by site-directed mutagenesis. Infliximab-induced apoptosis and cell cycle arrest were completely abrogated by substitution of all of these three cytoplasmic serine residues. In this study, we revealed that novel biological effects induced by infliximab and etanercept were mediated by reverse signaling of mTNF, which might explain the differential clinical efficacy of these anti-TNF-alpha. agents. We also clarified that cytoplasmic serine residues were critical for the signal transduction through mTNF.