Identification and functional analysis of non-antigenic factors of intracellular bacteria essential for the induction of cell-mediated protective immunity

细胞内细菌非抗原因子的鉴定和功能分析对于诱导细胞介导的保护性免疫至关重要

基本信息

批准号：
09470075
负责人：
MITSUYAMA Masao
金额：
$ 5.44万
依托单位：
KYOTO UNIVERSITY (1998-1999)Niigata University (1997)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

This study investigated the mechanism and the role of factors other than antigens from intracellular bacteria in the induction of T cell-mediated protective immunity. Results summarized as follows have been obtained.1. The endogenous production of γ-interferon-γ (IFN-γ) was essential for the induction of TH1-dependent immunity against intracellular bacteria. In this process, IL-12 was important among various cytokines produced by macrophages.2. One of the non-antigenic factor, LLO from Listeria monocytogenes, was highly capable of inducing cytokines. By using the liposome-encapsulated LLO in vivo, it was possible to induce the endogenous cytokines to the level comparable to that induced by immunization with viable bacteria (actual infection).3. Application of liposome-encapsulated LLO as a sort of adjuvant, a strong protective immunity could be induced after immunization of mice with LLO plus killed bacteria or LLO-negative strain, both of which are incapable of inducing protection if used alone.4. TH-1 dependent protection was ascribed to the activation of macrophages mainly induced by IFN-γ. The expression of enhanced bacterial killing in activated macrophages was due either to reactive oxygen intermediates or to reactive nitrogen intermediates, depending on the timing of activation and bacterial infection in macrophage level.5. A mechanism similar to the above appeared to be involved in the infection by Sporothrix schenkii, a possible intracellular parasitic fungus.6. In the induction of IFN-γ by LLO, both IL-12 and IL-18 were highly essential at the initial stage of macrophage stimulation by LLO. It was suggested that 15,000 kDa protein of the membrane was involved in the initial triggering.7. Among 4 domains of LLO molecule, 4th domain was indispensable for the expression of membrane damage. In contrast, domains 1 through 3 seemed to be essential for the expression of cytokine-inducing ability.

本研究探讨了细胞内细菌抗原以外的因素在诱导T细胞介导的保护性免疫中的作用，得到如下结果：1．内源性产生γ-干扰素-γ。 ) 对于诱导针对细胞内细菌的 TH1 依赖性免疫至关重要。在此过程中，IL-12 在巨噬细胞产生的各种细胞因子中非常重要。2. 来自单核细胞增生李斯特菌的非抗原性因子之一。具有很强的细胞因子诱导能力，通过在体内使用脂质体包裹的脂质体，可以将内源性细胞因子诱导至与活菌免疫（实际感染）诱导的水平相当。3．作为一种佐剂，LLO加灭活菌或LLO阴性菌株免疫小鼠后可诱导出较强的保护性免疫，两者单独使用均不能产生保护作用。 4． TH-1 依赖性保护归因于主要由 IFN-γ 诱导的巨噬细胞的激活。激活的巨噬细胞中增强的细菌杀灭作用的表达是由于活性氧中间体或活性氮中间体，具体取决于激活的时间和细菌感染。 5．申基孢子丝菌（一种可能的细胞内寄生真菌）的感染似乎与上述类似的机制有关。6．在LLO诱导IFN-γ的过程中，两者均存在。 IL-12和IL-18在LLO刺激巨噬细胞的初始阶段非常重要，表明膜上的15,000 kDa蛋白参与了初始触发。7．LLO分子的4个结构域中，第4个结构域是不可缺少的。相反，结构域 1 至 3 似乎对于细胞因子诱导能力的表达至关重要。