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 小鼠对粘膜病原体衣原体的免疫应答 沙眼细胞和分子机制的知识 被鼠宿主利用来清除衣原体感染是必需的 设计和开发成功的衣原体疫苗。 使用一组携带靶向突变的近交系小鼠品系， 多种免疫相关基因（基因敲除小鼠）， 我们发现生殖器对衣原体感染的免疫力 粘膜需要编码ab T的功能基因的存在 细胞受体分子和细胞因子IL-12、IFN-g和TNF-α。 编码gd T细胞受体、IL-6和IL-10的基因不表达。 必需的.这些数据表明，对衣原体的免疫是 由传统的IL-12驱动的1型CD 4 + T细胞介导， IFN-γ和TNF-α。这些细胞的分子机制 从受感染的上皮细胞中清除衣原体似乎 涉及Fas介导的凋亡或孔形成蛋白， 因为缺乏Fas或穿孔素基因的小鼠 与对照组一样有效。不同C. 沙眼分离株显示其对类型的敏感性差异 I细胞因子，IFN-g。在体内和体外，IFN-g抑制了 人类C.沙眼衣原体血清型A至K，但不是 小鼠肺炎（MoPn）。IFN-γ介导 体外人衣原体生长的抑制发生在 而不是衣原体抑制机制， 衣原体生长没有恢复后，删除的 抑制细胞因子。在小鼠细胞中，诱导型一氧化氮的刺激 一氧化氮合酶（iNOS）提供了IFN-γ的一种潜在机制 行动上然而，正常衣原体清除率的发现， iNOS缺陷小鼠和iNOS抑制剂不能 在体外反向干扰素-g介导的抑制，反对 这条路的重要作用。因此，分子机制 IFN-γ不可逆地限制衣原体生长的机制仍有待进一步研究。 测定人或鼠C.沙眼菌株 在没有TNF-α的情况下，另一种1型 感染时产生的细胞因子。TNF-α介导的抑制 然而，不能在体外复制，这表明 这种细胞因子的作用是间接涉及细胞和/或介质的 不存在于体外培养系统中。这些发现表明 成功的衣原体疫苗会招募分泌IFN-γ的T细胞， 将细胞转移到粘膜感染部位。他们还指出，使用 MoPn作为疫苗开发和测试的模型系统， 因为MoPn相对地对IFN-γ不敏感， 尽管1型CD 4 + T细胞介导的免疫的其它方面 可能在MoPn抗性中起重要作用。结合数据 定义淋巴细胞向衣原体感染的 粘膜（Z 01-AI-00771-02-LICP），这些研究提供了一个逻辑 开发和交付有效的理论基础 C.沙眼疫苗