EARLY ENDOTOXIN TOLERANCE: CELLULAR/MOLECULAR MECHANISMS

描述(摘自申请者摘要)：败血症和感染性休克 是重要的临床问题，约有50万例和80亿美元 每年的医疗费用。这个问题在密集的 在护理环境和免疫功能低下的患者中， 革兰氏阴性杆菌的内毒素外膜成分，早已 被认为是脓毒症死亡的主要因素，主要原因是 与炎性细胞因子的过度产生有关，这是由 内毒素与宿主巨噬细胞的相互作用。迄今为止，治疗性干预 靶向内毒素或单个内毒素诱导的细胞因子 令人失望。因此，对脂多糖作用机制的理解 分子和细胞水平仍然是一个重要的研究领域。 对这一理解的关键是描绘了分子机制 “早期内毒素耐受”(EET)，一种公认但知之甚少的疾病 一种现象，导致对随后的内毒素的不稳定状态 曝光。在体外，巨噬细胞对随后的内毒素具有“耐受性” 巨噬细胞可通过用脂多糖预处理来实现刺激。近期 研究有力地支持了“容忍”这一概念 根据其他内毒素的评估，内毒素反应伴随着活动增加 响应，从而产生了更广义的“重新编程”概念。 然而，体内EET与巨噬细胞“重编程”的关系 体外培养还不是很清楚。这项提案详细介绍了新的实验方法 定义调解EET的事件。需要检验的总体假设是， 内毒素与宿主巨噬细胞的初始相互作用启动了一个遗传过程 通过对PRO-AND盒式磁带的选择性调制来进行“重新编程” 抗炎介质基因，进而定义EET表型。这个 研究人员进一步假设，基因产物选择性地影响 通过“重新编程”深刻影响革兰氏阴性杆菌感染的过程。 他们的具体目的是为了(1)剖析特定的贡献 巨噬细胞亚群和基因已经牵涉到这一过程，(2)识别 促进EET的新基因以及评估EET对脓毒症的影响， 以及(3)分析特定的细胞内途径，以了解它们在 诱导/维持“容忍”。预计在……结束时 本研究，内毒素耐受的机制及其对 败血症和其他疾病的疾病结局将得到更好的了解。

DESCRIPTION (Adapted from the Applicant's Abstract): Sepsis and septic shock are important clinical problems, with about 500,000 cases and $8 billion in health care costs annually. This problem is exacerbated within the intensive care setting and in immunocompromised patients Lipopolysaccharide (LPS), the endotoxic outer membrane component of Gram negative bacteria, has long been implicated as a major contributing factor to mortality in sepsis, due largely to the overproduction of inflammatory cytokines that is initiated by the interaction of LPS with host macrophages. To date, therapeutic intervention targeting either LPS or individual LPS-induced cytokines has been disappointing. Thus, an understanding of the mechanisms of LPS action at the molecular and cellular level remain a significant area of investigation. Pivotal to this understanding is a delineation of molecular mechanisms of "early endotoxin tolerance" (EET), a well recognized, but poorly understood phenomenon that results in a state of refractoriness to subsequent LPS exposure. In vitro, a state of macrophage "tolerance" to subsequent LPS stimulation can be achieved by pre-treatment of macrophages with LPS. Recent studies have provided strong support for the concept that "tolerance" to some LPS responses is accompanied by increased activity as assessed by other LPS responses, thus leading to a more generalized concept of "reprogramming." However, the relationship between EET in vivo and macrophage "reprogramming" in vitro is not understood. This proposal details novel experimental approaches to define events that mediate EET. The overall hypothesis to be tested is that the initial interaction of LPS with host macrophages initiates a process of genetic "reprogramming" via selective modulation of a cassette of pro- and anti-inflammatory mediator genes that, in turn, defines the EET phenotype. The investigators further hypothesize that products of genes selectively affected by "reprogramming" profoundly influence the course of Gram negative infection. Their Specific Aims are designed to (1) dissect the contribution of specific macrophage subsets and genes already implicated in this process, (2) identify novel genes that contribute to EET and to evaluate the impact of EET on sepsis, and (3) analyze specific intracellular pathways for their potential role in the induction/maintenance of "tolerance." It is expected that, at the conclusion of this research, the mechanism of endotoxin tolerance and its potential impact on disease outcome in both sepsis and other diseases will be better understood.