Regulation of HMG-1 Release in Endotoxemia

内毒素血症中 HMG-1 释放的调节

基本信息

批准号：
6548053
负责人：
Haichao Wang
金额：
$ 22.68万
依托单位：
NORTH SHORE UNIVERSITY HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-07-01 至 2003-06-30
项目状态：
已结题

项目摘要

Gram negative bacterial infection is a widespread problem in critically ill patients. The high mortality of sepsis is in part mediated by bacterial endotoxin (LPS), which activates mitogen-activated protein (MAP) kinases (e.g., p38, ERK 1/2, and JNK), and stimulates the release of proinflammatory cytokines (e.g., TNF and IL-1beta), nitric oxide, platelet-activating factor, and other products. Macrophage-derived cytokines have been implicated in mediating lethal endotoxemia, because inhibition of their production or activity attenuates the development of tissue injury in animal models. If delivered early enough, anti-TNF can be an effective therapy in experimental models of endotoxemia, but early treatment is difficult to achieve in the clinic. An alternative strategy would be to identify "late" macrophage mediators that may be clinically more accessible. We recently identified a ubiquitous protein, HMGB1 (formerly known as HMG-1), as a late mediator of endotoxin lethality (Science 1999, 285: 248-251). HMGB1 is released late by LPS-stimulated macrophages, and its serum levels increase significantly between 16 to 32 hours after exposure to endotoxin. Anti-HMGB1 antibodies significantly protect against lethal endotoxemia and LPS-induced acute lung injury, even when antibody administration is delayed until after the early TNF response. Purified recombinant HMGB1 induced the release of multiple cytokines (e.g., TNF, IL-1beta and IL-6) in macrophage/monocyte cultures, and promoted tissue injury and even lethality when administered into mice. However, the mechanisms underlying the regulation of HMG-1 release and action are still unknown. The first aim of the studies outlined in this proposal is to determine the roles of early pro-inflammatory cytokines (e.g., TNF, IL-1beta) and MAP kinase (e.g., p38 and ERK1/2) signaling pathways in regulation of LPS-induced HMG-1 release in macrophage/monocyte cultures. This will be accomplished by examining the effect of TNF- or IL-1beta-specific neutralizing antibodies, as well as MAP kinase-specific inhibitors or anti- sense oligonucleotides on LPS-induced HMGB1 release. The second aim of this proposal is to examine the role of HMGB1 receptor (e.g., RAGE) and MAP kinases (e.g., p38, ERK1/2, and JNK) in regulation of HMGB1-induced cytokine production in macrophage/monocyte cultures. We will examine whether HMGB1 will activate MAP kinases, and whether RAGE-specific neutralizing antibodies or anti-sense oligonucleotides will prevent HMGB1- induced TNF release. Answers to these questions will shed light on the mechanisms underlying regulation of HMGB1 release and action, and improve our understanding of mechanisms underlying regulation of the innate immune response in endotoxemia.

革兰氏阴性细菌感染是危重患者中普遍存在的问题。脓毒症的高死亡率部分是由细菌内毒素 (LPS) 介导的，它会激活丝裂原激活蛋白 (MAP) 激酶（例如 p38、ERK 1/2 和 JNK），并刺激促炎细胞因子的释放（例如TNF和IL-1beta)、一氧化氮、血小板激活因子等产品。巨噬细胞衍生的细胞因子与介导致死性内毒素血症有关，因为抑制其产生或活性可减轻动物模型中组织损伤的发展。如果足够早，抗TNF药物可以成为内毒素血症实验模型的有效治疗方法，但早期治疗在临床上很难实现。另一种策略是识别临床上更容易接近的“晚期”巨噬细胞介质。我们最近发现了一种普遍存在的蛋白质 HMGB1（以前称为 HMG-1），它是内毒素致死性的晚期介质（Science 1999, 285: 248-251）。 HMGB1 由 LPS 刺激的巨噬细胞延迟释放，其血清水平在接触内毒素后 16 至 32 小时内显着增加。抗 HMGB1 抗体可显着预防致命性内毒素血症和 LPS 诱导的急性肺损伤，即使抗体给药延迟到早期 TNF 反应后也是如此。纯化的重组 HMGB1 诱导巨噬细胞/单核细胞培养物中多种细胞因子（例如 TNF、IL-1β 和 IL-6）的释放，并在给予小鼠时促进组织损伤甚至致死。然而，调节 HMG-1 释放和作用的机制仍不清楚。本提案中概述的研究的首要目的是确定早期促炎细胞因子（例如 TNF、IL-1β）和 MAP 激酶（例如 p38 和 ERK1/2）信号通路在 LPS 诱导的调节中的作用巨噬细胞/单核细胞培养物中 HMG-1 的释放。这将通过检查 TNF 或 IL-1β 特异性中和抗体以及 MAP 激酶特异性抑制剂或反义寡核苷酸对 LPS 诱导的 HMGB1 释放的影响来实现。该提案的第二个目的是检查 HMGB1 受体（例如 RAGE）和 MAP 激酶（例如 p38、ERK1/2 和 JNK）在调节巨噬细胞/单核细胞培养物中 HMGB1 诱导的细胞因子产生中的作用。我们将检查 HMGB1 是否会激活 MAP 激酶，以及 RAGE 特异性中和抗体或反义寡核苷酸是否会阻止 HMGB1 诱导的 TNF 释放。这些问题的答案将揭示 HMGB1 释放和作用的潜在调节机制，并提高我们对内毒素血症先天免疫反应调节的潜在机制的理解。