Regulation of signal transduction through toll like receptors (interleukin-1 receptor related) by stimulation of live Mycobacterium tuberculosis

我们之前已经发现，活的，但不是死亡的，结核分枝杆菌对人肺成纤维细胞系表现出细胞毒性(J干扰素细胞因子研究，2001，抗菌素。化学试剂，2002年)。为了研究活菌到宿主细胞的信号转导，我们研究了与白介素1受体(IL-1R)相关的Toll样受体(TLRs)的表达，以及活菌刺激后受体的信号转导。据报道，存在于分枝杆菌细胞壁中的脂蛋白是TLR2的主要配体，可诱导巨噬细胞凋亡。内毒素存在于革兰氏阴性菌的细胞壁中，通过TLR4传递其信号。在这项研究中，内毒素和转化生长因子β调节小鼠肝细胞上TLR2和TLR4的表达(免疫学，2003，J.白细胞生物学，2004)。已知的人成纤维细胞系MRC-5结构性地表达TLR1-10。核因子-kB的激活机制与IL-1R的激活机制密切相关。因此，我们研究了结核分枝杆菌活菌刺激后，MRC-5上核因子-kB的活化情况。活的，但不是死的，杆菌强烈地诱导NFkB，也诱导炎性细胞因子的表达。有趣的是，诱导核因子-kB和细胞因子的动力学与活细菌的细胞毒作用相似。这些数据表明，活菌刺激后TLRs的信号转导对人细胞的细胞毒作用有重要意义。此外，我们还成功地使用临床分离的结核分枝杆菌(抗菌药)进行了吡嗪酸敏感性试验的细胞毒性试验。化学试剂，2005)

We have previously revealed that live, but not dead, Mycobacterium tuberculosis exhibits cytotoxicity to human lung fibroblast cell line (J. Interferon Cytokine Res., 2001, Antimicrob. Agents Chemother., 2002). In order to investigate the signal transduction from live bacteria to host cell, we studied the expression of toll like receptors (TLRs), which are related to interleukin 1 receptor (IL-1R), and signal transduction from the receptors after stimulation with live bacilli. Lipoproteins which are present in cell wall of mycobacteria are reported as major ligand to TLR2 and induces apoptosis of macrophages. Lipopolysaccharide present in cell wall of gram-negative bacteria, transducer its signal through TLR4. In this study, LPS and transforming growth factor beta are revealed to regulate the expression of TLR2 and TLR4 on mouse hepatocyte (Immunology, 2003, J. Leukocyto Biol., 2004). Human fibroblast cell line, MRC-5, is known to constitutively expresses TLR1-10. The mechanism of activation of NF-kB is closely related to that of IL-1R. Therefore, we have investigated the activation of NF-kB on MRC-5 after stimulation of live M. tuberculosis. Live, but not dead, bacilli strongly induces NF kB and also induce expression of inflammatrical cytokines. Interestingly, the kinetics of induction of NF-kB and cytokines are similar to that of the effect of cytotoxicity of live bacilli. These data suggests that the signaling from TLRs after stimulation of live bacilli would have significance on the cytotoxicity to human cell. Further, we were also successful in applying the cytotoxicity testing for susceptibility test to pyrazinamic acid using clinical isolates of tuberculosis (Antimicrob. Agents Chemother., 2005)