Zhang Y, Doerfler M, Lee T C, Guillemin B, Rom W N
Department of Medicine, Bellevue Hospital Center, New York University Medical Center, New York 10016.
J Clin Invest. 1993 May;91(5):2076-83. doi: 10.1172/JCI116430.
The granulomatous immune response in tuberculosis is characterized by delayed hypersensitivity and is mediated by various cytokines released by the stimulated mononuclear phagocytes, including tumor necrosis factor-alpha (TNF alpha) and IL-1 beta. We have demonstrated that Mycobacterium tuberculosis cell wall component lipoarabinomannan (LAM), mycobacterial heat shock protein-65 kD, and M. tuberculosis culture filtrate, devoid of LPS as assessed by the Amebocyte Lysate assay, stimulate the production of TNF alpha and IL-1 beta proteins and mRNA from mononuclear phagocytes (THP-1 cells). The effect of LAM on the release of these cytokines was specific, as only LAM stimulation was inhibited by anti-LAM monoclonal antibody. Interestingly, we found that LAM and Gram-negative bacterial cell wall-associated endotoxin LPS may share a similar mechanism in their stimulatory action as demonstrated by inhibition of TNF alpha and IL-1 beta release by monoclonal antibodies to CD14. Anti-CD14 monoclonal antibody MY4 inhibited both TNF alpha and IL-1 beta release with LAM and LPS but no effect was observed with other mycobacterial proteins. An isotype antibody control did not inhibit release of cytokines under the same experimental conditions. M. tuberculosis and its components upregulated IL-1 beta and TNF alpha mRNAs in THP-1 cells. Nuclear run-on assay for IL-1 beta demonstrated that LAM increased the transcription rate. The induction of IL-1 beta was regulated at the transcriptional level, in which these stimuli acted through cis-acting element(s) on the 5' flanking region of the IL-1 beta genomic DNA. M. tuberculosis cell wall component LAM acts similarly to LPS in activating mononuclear phagocyte cytokine TNF alpha and IL-1 beta release through CD14 and synthesis at the transcriptional level; both cytokines are key participants in the host immune response to tuberculosis.
结核病中的肉芽肿性免疫反应以迟发型超敏反应为特征，由受刺激的单核吞噬细胞释放的多种细胞因子介导，包括肿瘤坏死因子-α（TNFα）和白细胞介素-1β（IL-1β）。我们已经证明，结核分枝杆菌细胞壁成分脂阿拉伯甘露聚糖（LAM）、分枝杆菌热休克蛋白65kD以及经鲎试剂检测不含脂多糖（LPS）的结核分枝杆菌培养滤液，可刺激单核吞噬细胞（THP-1细胞）产生TNFα和IL-1β蛋白及mRNA。LAM对这些细胞因子释放的作用具有特异性，因为只有LAM刺激可被抗LAM单克隆抗体抑制。有趣的是，我们发现LAM与革兰氏阴性菌细胞壁相关内毒素LPS在刺激作用中可能具有相似机制，这一点通过抗CD14单克隆抗体抑制TNFα和IL-1β释放得以证明。抗CD14单克隆抗体MY4可抑制LAM和LPS诱导的TNFα和IL-1β释放，但对其他分枝杆菌蛋白则无作用。在相同实验条件下，同型抗体对照未抑制细胞因子的释放。结核分枝杆菌及其成分上调了THP-1细胞中IL-1β和TNFα的mRNA水平。对IL-1β进行的核转录分析表明，LAM提高了转录速率。IL-1β的诱导在转录水平受到调控，这些刺激通过IL-1β基因组DNA 5'侧翼区域的顺式作用元件发挥作用。结核分枝杆菌细胞壁成分LAM在通过CD14激活单核吞噬细胞细胞因子TNFα和IL-1β释放以及在转录水平合成方面与LPS作用相似；这两种细胞因子都是宿主对结核病免疫反应的关键参与者。
