Host defense functions of M. tuberculosis lipoglycan

描述(改编自申请者摘要)：结核病(TB)是 传染病致死的主要原因。巨噬细胞起着关键作用。 通过一氧化氮的表达控制结核分枝杆菌 氧化物(No.)和肿瘤坏死因子α。一氧化氮在小鼠体内发挥重要的分枝杆菌杀灭作用 结核病，并越来越多地认识到对人类的重要性。整体而言 这一提议的假设是巨噬细胞，通过特定的表面 受体(S)，识别分枝杆菌细胞壁产物启动iNOS-和 TnFa-诱导。因此，这项建议的重点是：一)确定 INOS和TNFa的受体及其信号调节机制 暴露于分枝杆菌细胞壁成分脂阿拉伯甘露聚糖(ManLAM) 以及ii)确定这些组件中的每一个的重要性 体外感染模型。基于实验表明巨噬细胞来自 Toll样受体4(TLR4)突变的C3H/HeJ小鼠 干扰素对巨噬细胞TLR4表达的影响 ManLAM，我们假设ManLAM与TLR结合，诱导iNOS-NO*/TNFa 表情。由于耻垢分枝杆菌诱导的非甘露糖帽LAM(AraLAM) 比ManLAM更重要的是表达，我们假设II)暴露的 ManLAM或AraLAM上的阿拉伯糖残基是与ManLAM结合的成分 至其推定的TLR。因为初步研究表明，有丝分裂原激活 蛋白激酶(MAPK)和NFkB信号通路调节iNOS和TNFa 表达，我们假设近端的激酶MAP/ERK激酶 (Mekk)是ManLAM诱导iNOS和TNFa的关键调节因子。最后， 由于TLR识别病原体衍生的分子并增强宿主防御能力，我们 假设阻断一个或多个TLR将促进M。 抑制NO*和TNFa的表达。这些假设将是 通过三个具体目标解决：1.确定满足以下条件的ManLAM结构 介导iNOS-NO*/TNFa的诱导及其受体 ManLAM效应。2.研究MAPK和NFkB信号转导途径的作用 甘露聚糖和其他脂多糖诱导iNOS-NO*和TNFa的途径。3.至 阐明TLRs、MAPK和NFkB信号通路以及ManLAM在 控制结核分枝杆菌在小鼠和人巨噬细胞中的生长 对生长的影响与NO*和TNFa表达相关。

DESCRIPTION (Adapted from the Applicant's Abstract): Tuberculosis (TB) is the leading cause of death by an infectious agent. Macrophages play a pivotal role in the control of Mycobacterium tuberculosis through the expression of nitric oxide (NO.) and TNFalpha. NO plays an important mycobactericidal role in murine TB and is increasingly recognized to be important in humans. The overall hypothesis of this proposal is that macrophages, by specific surface receptor(s), recognize mycobacterial cell wall products to initiate iNOS- and TNFa-induction. Hence, the focus of this proposal is to: i) determine the receptor and signaling mechanisms which regulate iNOS and TNFa following exposure to the mycobacterial cell wall component lipoarabinomannan (ManLAM) and ii) to determine the significance of each of these components in an in vitro model of infection. Based on experiments showing that macrophages from the Toll-like receptor 4 (TLR4)-mutant C3H/HeJ mice produced significantly lower levels of NO than TLR4-intact C3H/HeN macrophages in response to IFNg + ManLAM, we hypothesize that ManLAM engages a TLR to induce iNOS-NO*/ TNFa expression. Since non-mannose capped LAM (AraLAM) from M. smegmatis induced greater NO about expression than ManLAM, we hypothesize that ii) the exposed arabinose residues on ManLAM or AraLAM are the components of ManLAM that bind to its putative TLR. Since initial studies show that the mitogen-activated protein kinases (MAPKs) and NFkB signaling pathways regulate iNOS and TNFa expression, we hypothesize that the proximal kinase MAP/ERK kinase kinase (MEKK) is a pivotal regulator for ManLAM-induction of iNOS and TNFa. Lastly, because TLRs recognize pathogen-derived molecules and enhance host-defenses, we hypothesize that blocking one or more of the TLRs will enhance the growth of M. tuberculosis and inhibit NO* and TNFa expression. These hypotheses will be addressed by three specific aims: 1. To determine the ManLAM structures that mediate the induction of iNOS-NO*/TNFa and the receptor that mediates these ManLAM effects. 2. To investigate the role of the MAPK and NFkB signaling pathways in ManLAM- and other lipoglycan-induced iNOS-NO* and TNFa. 3. To elucidate the role of the TLRs, MAPK and NFkB signaling pathways, and ManLAM in controlling the growth of M. tuberculosis in mouse and human macrophages and to correlate effects on growth with NO* and TNFa expression.