Wang P, Wu P, Siegel M I, Egan R W, Billah M M
Schering-Plough Research Institute, Kenilworth, NJ 07033.
J Immunol. 1994 Jul 15;153(2):811-6.
Upon addition of LPS to human PBMCs, IL-1 beta, IL-6, and TNF-alpha were released in the culture media in a time-dependent manner. Cytokine release began 2 h after LPS addition and maximal release of all three cytokines was observed between 6 and 8 h. Northern analysis revealed that, for each cytokine, mRNA accumulation preceded protein release. When added either 2 h before or at the same time as LPS, IL-10 inhibited both the cytokine release and mRNA accumulation almost completely. Similar inhibition was observed when IL-10 was added 2 h after LPS, a time point that coincided with the onset of the rapid burst of cytokine mRNA accumulation. The inhibitory activity of IL-10 was abrogated by cycloheximide, suggesting an involvement of newly synthesized proteins in IL-10 action. By using nuclear run-on transcription assays, we have found that IL-10 inhibited transcription of all three cytokine genes in LPS-stimulated PBMCs. In contrast, IL-10 moderately enhanced degradation of IL-6 mRNA, but not of mRNAs for IL-1 beta and TNF-alpha. Thus, the present study provides the first evidence that, in human PBMCs, IL-10 inhibits cytokine synthesis by acting mainly at the level of cytokine gene transcription.
向人外周血单个核细胞（PBMCs）中加入脂多糖（LPS）后，白细胞介素-1β（IL-1β）、白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）以时间依赖性方式在培养基中释放。细胞因子释放于加入LPS后2小时开始，并且在6至8小时之间观察到所有三种细胞因子的最大释放。Northern分析显示，对于每种细胞因子，mRNA积累先于蛋白质释放。当在LPS之前2小时或与LPS同时加入时，IL-10几乎完全抑制细胞因子释放和mRNA积累。当在LPS后2小时加入IL-10时也观察到类似的抑制作用，这一时间点与细胞因子mRNA积累的快速爆发开始时间一致。IL-10的抑制活性被放线菌酮消除，表明新合成的蛋白质参与IL-10的作用。通过使用核转录分析，我们发现IL-10抑制LPS刺激的PBMCs中所有三种细胞因子基因的转录。相反，IL-10适度增强IL-6 mRNA的降解，但不增强IL-1β和TNF-α的mRNA降解。因此，本研究提供了首个证据，即在人PBMCs中，IL-10主要通过作用于细胞因子基因转录水平来抑制细胞因子合成。
