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反应 沙眼衣原体。细胞和分子机制的知识 需要被鼠宿主用来清除衣原体感染 设计和开发成功的衣原体疫苗。 使用一组带有目标突变的近交小鼠品系 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 的基因未 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 从受感染的上皮细胞中消除衣原体似乎并没有 涉及Fas介导的细胞凋亡或孔形成蛋白， 穿孔素，因为缺乏 Fas 或穿孔素基因的小鼠被清除 感染与控制一样有效。不同C的比较 沙眼分离株显示其对该类型的敏感性存在差异 I 细胞因子，IFN-g。在体内和体外，IFN-g 均抑制 人类沙眼衣原体血清型 A 至 K 的生长，但不生长 鼠株，小鼠肺炎（MoPn）。 IFN-g介导的 体外人衣原体生长的抑制作用是通过 衣原体酸机制而非衣原体抑制机制 去除衣原体后，衣原体生长没有恢复 抑制细胞因子。在小鼠细胞中，刺激诱导型硝酸 氧化物合酶 (iNOS) 提供了 IFN-g 的一种潜在机制 行动。然而，衣原体清除率正常的发现 iNOS 缺陷小鼠和 iNOS 抑制剂无法 体外逆转 IFN-g 介导的抑制作用反对 该途径发挥着重要作用。因此，分子机制 IFN-g 能否不可逆转地限制衣原体生长仍有待研究 决定。人或鼠沙眼衣原体菌株感染 在没有 TNF-a（另一种 1 型）的情况下受到轻微抑制 感染过程中产生的细胞因子。 TNF-α介导的抑制 然而，无法在体外复制，这表明 该细胞因子的作用是间接涉及细胞和/或介质 不存在于体外培养系统中。这些发现表明 成功的衣原体疫苗将招募分泌 IFN-g 的 T 细胞到达粘膜感染部位。他们还指出，使用 MoPn 作为疫苗开发和测试的模型系统可能 是不合适的，因为 MoPn 对 IFN-g 相对不敏感， 尽管 1 型 CD4+ T 细胞介导的免疫的其他方面 可能对 MoPn 抗性很重要。结合数据 定义淋巴细胞向衣原体感染的运输 粘膜（Z01-AI-00771-02-LICP），这些研究提供了逻辑 开发和提供有效的理论基础 沙眼衣原体疫苗。