M. avium GPLs in macrophage activation and virulence

M. avium GPL 在巨噬细胞激活和毒力中的作用

• 批准号: 6868878
• 负责人: JEFFREY Scott SCHOREY
• 金额: $ 30.28万
• 依托单位: UNIVERSITY OF NOTRE DAME
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-15 至 2009-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6868878
• 关键词: Mycobacterium avium; bacterial cytopathogenic effect; biochemistry; biological signal transduction; cell wall; centrifugation; disease /disorder model; gene mutation; glycopeptides; host organism interaction; immune response; laboratory mouse; leukocyte activation /transformation; lipid biosynthesis; macrophage; mitogen activated protein kinase; peptide structure; thin layer chromatography; virulence

DESCRIPTION (PROVIDED BY APPLICANT): Mycobacterial infections result in the activation of macrophage signaling pathways that are essential for stimulating a host immune response. However our understanding is limited as to which signaling pathways are transduced in macrophages upon mycobacterial invasion and whether pathogenic mycobacteria modulate these signals. In our experiments to define the macrophage signaling pathways initiated during a mycobacterial infection we determined that the mitogen activated protein kinases (MAPK) p38 and ERK 1/2 were activated in murine macrophages upon mycobacterial infection. However, the MAPK activity was limited in macrophages infected with pathogenic M. avium strains relative to cells infected with non-pathogenic mycobacteria. A limited production of TNF-alpha was also observed in these M. avium infected cells. Inhibitor studies indicated that the MAPKs were required for the mycobacteria-mediated induction of TNF-alpha. Moreover, macrophages infected with a glycopeptidolipid (GPL) deficient M. avium 2151 also showed increased MAPK activation and TNF-alpha production compared to cells infected with a isogenic 2151 strain containing GPLs. Therefore, we hypothesize that the MAPKs are key components in the macrophage signaling pathways initiated during a mycobacterial infection and that M. avium has evolved mechanisms to limit their activity in part through production of GPLs. Additional analysis showed that modifying the GPL structure through deletion of the methyl transferase D gene resulted in a M. avium 104 strain with attenuated virulence. Thus, we propose the following specific aims: 1) produce a panel of M. avium 724 and 104 mutants that lack specific genes involved in GPL biosynthesis 2) Biochemically characterize the M. avium mutants for GPL structure and cell wall composition 3) Characterize GPLs for their affect on macrophage activation and mycobacterial virulence. Our long-term goal is to better understand the macrophage signaling pathways initiated during a mycobacterial invasion. We believe a more careful analysis of these macrophage responses and how mycobacteria may modify them will lead to novel insights into mycobacterial pathogenesis.

描述（由申请人提供）：分枝杆菌感染导致巨噬细胞信号通路激活，这对于刺激宿主免疫反应至关重要。然而，我们对分枝杆菌入侵时巨噬细胞中转导哪些信号通路以及致病性分枝杆菌是否调节这些信号的理解有限。 在我们定义分枝杆菌感染期间启动的巨噬细胞信号通路的实验中，我们确定丝裂原激活蛋白激酶 (MAPK) p38 和 ERK 1/2 在分枝杆菌感染时在小鼠巨噬细胞中被激活。然而，相对于感染非致病性分枝杆菌的细胞，感染致病性鸟分枝杆菌菌株的巨噬细胞中 MAPK 活性受到限制。在这些鸟分枝杆菌感染的细胞中也观察到了有限的 TNF-α 产生。抑制剂研究表明，分枝杆菌介导的 TNF-α 诱导需要 MAPK。此外，与感染含有 GPL 的同基因 2151 菌株的细胞相比，感染糖肽脂 (GPL) 缺陷型 M. avium 2151 的巨噬细胞也显示出增加的 MAPK 激活和 TNF-α 产生。因此，我们假设 MAPK 是分枝杆菌感染期间启动的巨噬细胞信号传导途径的关键组成部分，并且鸟分枝杆菌已经进化出部分通过产生 GPL 来限制其活性的机制。进一步的分析表明，通过删除甲基转移酶 D 基因来修改 GPL 结构会产生毒力减弱的 M. avium 104 菌株。因此，我们提出以下具体目标：1) 产生一组缺乏参与 GPL 生物合成的特定基因的 M. avium 724 和 104 突变体 2) 对 M. avium 突变体的 GPL 结构和细胞壁组成进行生化表征 3) 表征 GPL因为它们对巨噬细胞活化和分枝杆菌毒力的影响。我们的长期目标是更好地了解分枝杆菌入侵期间启动的巨噬细胞信号通路。我们相信，对这些巨噬细胞反应以及分枝杆菌如何改变它们进行更仔细的分析将为分枝杆菌发病机制带来新的见解。