The Molecular Target of Isoniazid in Pathogenic Mycobacteria

异烟肼在致病分枝杆菌中的分子靶点

• 批准号: 6099057
• 负责人: Clifton Barry
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6099057
• 关键词: Mycobacterium avium; Mycobacterium tuberculosis; drug metabolism; drug resistance; gene expression; isoniazid; peroxidases

These studies were aimed at characterization of the murine immune response to the mucosal pathogen, Chlamydia trachomatis. Knowledge of the cellular and molecular mechanism(s) utilized by the murine host to clear chlamydial infections is required for design and development of a successful chlamydial vaccine. Using a panel of inbred mouse strains bearing targeted mutations in a variety of immunologically relevant genes (gene knockout mice), we found that immunity to chlamydial infection of the genital mucosa required the presence of functional genes encoding the ab T cell receptor molecule and the cytokines IL-12, IFN-g and TNF- a. Genes encoding the gd T cell receptor, IL-6, and IL-10 were not required. These data indicated that immunity to Chlamydia is mediated by traditional IL-12-driven type 1 CD4+ T cells secreting IFN-g and TNF-a. The molecular mechanism by which these cells eliminate Chlamydia from infected epithelial cells did not appear to involve Fas-mediated apoptosis or the pore forming protein, perforin, since mice lacking the Fas or perforin genes cleared infections as efficiently as controls. Comparison of distinct C. trachomatis isolates revealed variation in their sensitivity to the type I cytokine, IFN-g. Both in vivo and in vitro, IFN-g inhibited the growth of human C. trachomatis serovars A through K but not the murine strain, mouse pneumonitis (MoPn). IFN-g-mediated inhibition of human chlamydial growth in vitro occurred by chlamydiacidal rather than chlamydiastatic mechanisms since chlamydial growth did not resume following removal of the inhibiting cytokine. In murine cells, stimulation of inducible nitric oxide synthase (iNOS) provides one potential mechanism of IFN-g action. However, the finding of normal chlamydial clearance in iNOS deficient mice and the inability of an iNOS inhibitor to reverse IFN-g-mediated inhibition in vitro argued against a significant role for this pathway. Thus, the molecular mechanism whereby IFN-g irreversibly limits chlamydial growth remains to be determined. Infections with human or murine C. trachomatis strains were marginally inhibited in the absence of TNF-a, another type 1 cytokine produced during infection. TNF- a-mediated inhibition could not be reproduced in vitro, however, suggesting that the action of this cytokine is indirect involving cells and/or mediators not present in the in vitro culture system. These findings indicate that the successful Chlamydia vaccine will recruit IFN-g-secreting T cells to the site of mucosal infection. They also indicate that use of MoPn as a model system for vaccine development and testing may be inappropriate since MoPn is relatively IFN-g-insensitive, although other aspects of type 1 CD4+ T cell-mediated immunity are probably important in MoPn resistance. Combined with data defining the trafficking of lymphocytes to Chlamydia-infected mucosae (Z01-AI-00771-02-LICP), these studies provide a logical theoretical basis for the development and delivery of an efficacious C. trachomatis vaccine.

这些研究旨在表征 鼠免疫反应对粘膜病原体，衣原体 气管。了解细胞和分子机制 需要鼠宿主使用来清除衣原体感染 用于成功的衣原体疫苗的设计和开发。 使用一组带有靶向突变的近交小鼠应变 多种免疫学相关的基因（基因基因敲除小鼠）， 我们发现对生殖器的衣原体感染的免疫力 粘膜需要存在编码AB T的功能基因 细胞受体分子和细胞因子IL-12，IFN-G和TNF- a。 编码GD T细胞受体，IL-6和IL-10的基因不是 必需的。这些数据表明对衣原体的免疫力是 由传统IL-12驱动的1型CD4+ T细胞分泌介导 IFN-G和TNF-A。这些细胞的分子机制 从感染上皮细胞中消除衣原体似乎没有 涉及FAS介导的凋亡或形成孔的蛋白质， perforin，因为缺少FAS或穿孔基因的小鼠清除了 感染与对照一样有效。比较不同的C 气囊分离株揭示了它们对类型的敏感性的变化 我的Cytokine，IFN-G。在体内和体外，IFN-G都抑制了 人梭状芽胞庭的生长血清c。 鼠菌株，小鼠肺炎（MOPN）。 IFN-G介导的 在体外抑制人类囊肿生长是由 衣原体型，而不是衣原体的司司机制 拆除后，衣原体增长没有恢复 抑制细胞因子。在鼠细胞中，刺激诱导量 氧化物合酶（INOS）提供了IFN-G的一种潜在机制 行动。但是，发现正常的衣原体间隙 iNOS缺乏小鼠和iNOS抑制剂无法 反向IFN-G介导的体外抑制作用反对A 该途径的重要作用。因此，分子机制 IFN-G不可逆地限制衣原体增长仍然是 决定。人类或鼠类沙眼菌株感染 在没有TNF-A的情况下，略有抑制，另一种类型1 感染过程中产生的细胞因子。 TNF-A介导的抑制作用 然而，无法在体外复制，表明 该细胞因子的作用是涉及细胞和/或介质的间接作用 不存在体外培养系统中。这些发现表明 成功的衣原体疫苗将招募IFN-G分泌T 细胞进入粘膜感染部位。他们还表明使用 MOPN作为疫苗开发和测试的模型系统可能 由于MOPN相对敏感，因此不合适， 虽然1型CD4+ T细胞介导的免疫的其他方面 在MOPN抗性中可能很重要。与数据结合 定义淋巴细胞的贩运对衣原体感染 粘膜（Z01-AI-00771-02-LECP），这些研究提供了逻辑 开发和交付有效的理论基础 C.沙眼疫苗。