Phongsisay Vongsavanh, Iizasa Ei'ichi, Hara Hiromitsu, Yoshida Hiroki
Division of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan.
Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University, Japan.
Immunobiology. 2017 Apr;222(4):664-671. doi: 10.1016/j.imbio.2016.12.004. Epub 2016 Dec 30.
Activation of the innate immunity by adjuvants, such as pertussis toxin (PTX), in the presence of autoreactive lymphocytes and antigen mimicry is sufficient to trigger autoimmunity. Toll-like, C-type lectin, and immunglobulin-like receptors play an important role in the innate immunity by sensing a variety of microbial products through several adaptor proteins, including MyD88, DAP12, and FcRγ. This study investigated the interaction between PTX and innate immune components. The direct interactions between coated PTX and receptor-fusion proteins were examined using ELISA-based binding assays. Functionally, PTX-binding receptors could be classified into two groups: inhibition (DAP12-coupled TREM2, ITIM-bearing SIRPα, SIGNR1/SIGNR3/DCSIGN) and activation (MyD88-associated TLR4, DAP12-coupled LMIR5/CD300b, FcRγ-coupled LMIR8/CD300c, CLEC9A, MGL-1). DAP12, MyD88, and FcRγ were selected for further investigation. A comprehensive analysis of gene transcription showed that PTX up-regulated the expression of various inflammatory mediators. DAP12 deficiency resulted in reduction or enhancement of inflammatory responses in a cytokine-specific manner. PTX was able to activate the TREM2-DAP12 signalling pathway. PTX induced lower expression of inflammatory mediators in the absence of FcRγ alone and substantially lost its inflammatory capacity in the absence of both FcRγ and MyD88. PTX was able to activate the MyD88-NF-κB signalling pathway in the presence of TLR2 or TLR4. The inflammatory activity of PTX was completely lost by heating. These results demonstrate that PTX targets the innate immunity through DAP12, FcRγ, and MyD88 providing new insights into the immunobiology of PTX.
在自身反应性淋巴细胞和抗原模拟存在的情况下，佐剂如百日咳毒素（PTX）激活先天免疫足以引发自身免疫。Toll样受体、C型凝集素受体和免疫球蛋白样受体通过包括MyD88、DAP12和FcRγ在内的多种衔接蛋白感知多种微生物产物，在先天免疫中发挥重要作用。本研究调查了PTX与先天免疫成分之间的相互作用。使用基于ELISA的结合试验检测包被的PTX与受体融合蛋白之间的直接相互作用。在功能上，PTX结合受体可分为两组：抑制性（DAP12偶联的TREM2、含ITIM的SIRPα、SIGNR1/SIGNR3/DCSIGN）和激活性（MyD88相关的TLR4、DAP12偶联的LMIR5/CD300b、FcRγ偶联的LMIR8/CD300c、CLEC9A、MGL-1）。选择DAP12、MyD88和FcRγ进行进一步研究。基因转录的综合分析表明，PTX上调了多种炎症介质的表达。DAP12缺陷以细胞因子特异性方式导致炎症反应的减少或增强。PTX能够激活TREM2-DAP12信号通路。单独缺乏FcRγ时，PTX诱导的炎症介质表达较低，而在同时缺乏FcRγ和MyD88时，其炎症能力基本丧失。在存在TLR2或TLR4的情况下，PTX能够激活MyD88-NF-κB信号通路。加热后PTX的炎症活性完全丧失。这些结果表明，PTX通过DAP12、FcRγ和MyD88靶向先天免疫，为PTX的免疫生物学提供了新的见解。
