MECHANISM OF ACTIVATION OF MACROPHAGES BY BACTERIAL LIPOPOLYSACCHARIDES

细菌脂多糖激活巨噬细胞的机制

• 批准号: 6237206
• 负责人: DAVID C. MORRISON
• 金额: $ 20.92万
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-12-20 至 1997-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6237206
• 关键词: bacterial polysaccharides; biological signal transduction; cell adhesion molecules; cytotoxicity; immunocytochemistry; laboratory mouse; leukocyte activation /transformation; lipopolysaccharides; macrophage; nitric oxide; northern blottings; tumor necrosis factor alpha

The long-term goal of this research is an understanding of molecular mechanisms of lipopolysaccharide (LPS)-initiated signalling as a model system by which the tumoricidal potential of the activated macrophage in treating cancer may be assessed. LPS has been recognized for several decades as among the most potent stimuli for the activation of macrophages for tumor cell killing. Increasing experimental evidence has implicated several macrophage membrane structures as potentially important receptors for activation and resultant signal transduction. These include the phosphatidyl-inositol linked CD14 glycoprotein, the p73 LPS binding protein and the CD11/18 adhesins. The precise contribution of each of these molecules to the actual activation event has not yet been established and Specific Aim #1 of the proposed research is to define the relative role of these various membrane LPS binding proteins and mechanisms of macrophage activation. It is our hypothesis that activation will depend upon the macromolecular structure of the LPS, and the intrinsic accessibility of lipid A for binding and the prior influence of environmental factors; we also hypothesize that there is one central pathway for LPS activation events. LPS-dependent macrophage activation results in the production of multiple proinflammatory mediators, including tumor necrosis factor (TNF) and nitric oxide (NO). Both of these have been shown to contribute to killing of tumor cells by LPS activated macrophages. Recent studies from this laboratory have shown that macrophages, pretreated in vitro with very low concentrations of LPS (which are not sufficient to induce either TNF or NO secretion) can nevertheless induce profound alterations in these cells such that subsequent activation with LPS or other stimuli results in markedly altered responses in terms of TNF and NO secretion. These alterations in TNF and NO responses are biophasic and reciprocal, and represent components of earlier-described macrophage desensitization and priming. We have termed this process macrophage "reprogramming" and a second Specific Aim of the proposed research will be to investigate the biochemical and cellular basis for this phenomenon. Particular attention will focus upon the potential role of a pertussis-toxin sensitive G- protein, which has been shown by others to contribute to LPS-dependent signalling of macrophages and by us to parallel many aspects of LPS- dependent macrophage reprogramming. We also hypothesize that reprogramming of macrophages occurs in vivo and that such events are of importance in the ability of the host to kill tumors. Studies in the third Specific Aim, therefore, will seek to establish macrophage reprogramming events as the primary explanation for induction of LPS tolerance or tumor-mediated LPS hypersensitivity reactions.

这项研究的长期目标是了解分子 脂多糖（LPS）启动的信号传导机制作为模型 系统，通过该系统，活化的巨噬细胞的杀肿瘤潜力在 可以评估治疗癌症。 LPS已被确认为几个 几十年来，作为最有力的刺激激活 巨噬细胞用于肿瘤细胞杀伤。 越来越多的实验证据表明 暗示了几种巨噬细胞膜结构 活化和信号转导的重要受体。 这些包括磷脂酰肌醇连接的CD 14糖蛋白，p73 LPS结合蛋白和CD 11/18粘附素。 精确贡献 这些分子中的每一个的实际激活事件还没有 已建立，拟议研究的具体目标#1是 确定这些不同的膜LPS结合蛋白的相对作用 和巨噬细胞活化的机制。 我们假设 活化将取决于LPS的大分子结构，并且 脂质A结合的固有可及性和先前的 环境因素的影响;我们也假设有一个 LPS激活事件的中心途径。 LPS依赖性巨噬细胞 激活导致产生多种促炎性细胞因子， 介质，包括肿瘤坏死因子（TNF）和一氧化氮（NO）。 这两种物质都被证明有助于杀死肿瘤细胞， LPS激活巨噬细胞。 该实验室最近的研究表明， 显示在体外用非常低的浓度预处理的巨噬细胞 LPS（不足以诱导TNF或NO分泌） 然而却能在这些细胞中引起深刻的变化， 随后用LPS或其它刺激物激活导致显著的 在TNF和NO分泌方面改变反应。 这些改变 在TNF和NO反应中是双相的和相互的， 这是先前描述的巨噬细胞脱敏和引发的组成部分。 我们将这一过程称为巨噬细胞“重编程”， 拟议研究的具体目的是调查 生物化学和细胞学的基础。 特别注意 将集中在百日咳毒素敏感的G- 蛋白质，已被其他人证明有助于LPS依赖性 巨噬细胞的信号传导，并通过我们来平行LPS的许多方面- 依赖巨噬细胞重编程。 我们还假设， 巨噬细胞的重编程发生在体内，并且这些事件是 重要性在于宿主杀死肿瘤的能力。 的研究 因此，第三个具体目标将寻求建立巨噬细胞 重编程事件作为LPS诱导的主要解释 耐受性或肿瘤介导的LPS超敏反应。