Regulation of HMGB1 Release in Endotoxemia.

项目摘要： 尽管最近在抗生素治疗和重症监护方面取得了进展，但细菌感染和败血症仍然存在。 危重病人中普遍存在的问题，仅在美国每年就有22.5万名受害者。这个 脓毒症的发病机制尚不清楚，但部分是由细菌毒素(如脂多糖、 脂蛋白)，刺激巨噬细胞/单核细胞按顺序提前释放(例如，肿瘤坏死因子和干扰素-γ)， 中级(如血清淀粉样蛋白A，SAA)和晚期(如HMGB1和组蛋白)促炎作用 调解人。HMGB1作为致死性全身炎症(LSI)晚期介质的开创性发现 (Science，285248-51,1999)促进了对各种早期细胞因子(如干扰素-γ)和肝脏- 衍生的急性时相蛋白(例如，胎球蛋白-A和SAA)在调节HMGB1释放中的作用。搜索其他 内源性HMGB1调节因子，系统监测循环HMGB1和HMGB1的动态变化 其他蛋白质在正常健康受试者和脓毒症患者之间，并发现之间呈负相关 循环中HMGB1和纤溶酶原结合蛋白TN的水平 纤溶酶原(PLMG)激活纤溶酶(PLM)依赖的纤溶作用。此外，我们还产生了 高纯度重组TN剂量依赖地减弱LPS/SAA诱导的炎症反应的初步研究 HMGB1的释放，但特异性地刺激几种中性粒细胞趋化因子(CXCL1)的释放 和CXCL5)。在致死性内毒素血症和脓毒症的动物模型中(由 盲肠结扎和穿孔，循环TN水平呈时间依赖性下降； 补充高纯度的重组TN提供了显著的保护作用。这些令人兴奋的东西 这些发现提出了几个关于TN介导的复杂机制的重要问题 抑制HMGB1的释放，以及对LSI的显著保护作用。因此，我们建议测试：1) TN差异性调节HMGB1释放和中性粒细胞趋化因子的新假说 通过不同的机制表达(目标1)；2)利用基因表达TN在LSI中的作用被低估 敲除或补充重组TN或TN特异性多肽激动剂(目标2)；以及3)新的 TN或TN特异性多肽激动剂影响LSI结局的机制(目标3)。总而言之， 这些建议的研究将提高我们对内毒素血症和败血症的病理生理学的了解，以及 帮助确定治疗脓毒症和其他炎症性疾病的新治疗策略。

Project Abstract: Despite recent advances in the antibiotic therapy and intensive care, bacterial infections and sepsis remain widespread problems in critically ill patients, annually claiming > 225,000 victims in the U.S. alone. The pathogenesis of sepsis remains obscure, but is partly mediated by bacterial toxins (e.g., lipopolysaccharide, LPS), which stimulate macrophages/monocytes to sequentially release early (e.g., TNF and IFN-γ), intermediate (e.g., the Serum Amyloid A, SAA), and late (e.g., HMGB1 and histones) pro-inflammatory mediators. Our seminal discovery of HMGB1 as a late mediator of lethal systemic inflammation (LSI) (Science, 285: 248-51, 1999) has prompted the investigation of various early cytokines (e.g., IFN-γ) and liver- derived acute-phase proteins (e.g., fetuin-A and SAA) in the regulation of HMGB1 release. To search for other endogenous HMGB1 regulators, we systematically monitored the dynamic changes of circulating HMGB1 and other proteins in normal healthy subjects versus septic patients, and found a negative correlation between levels of circulating HMGB1 and tetranectin (TN), a plasminogen-binding protein implicated in binding plasminogen (PLMG) to activate the plasmin (PLM)-dependent fibrinolysis. Furthermore, we have generated preliminary data that the highly purified recombinant TN dose-dependently attenuated the LPS/SAA-induced HMGB1 release, but specifically stimulated the release of several neutrophil-attracting chemokines (CXCL1 and CXCL5) by primary human monocytes. In animal models of lethal endotoxemia and sepsis (induced by cecal ligation and puncture, CLP), circulating TN levels were time-dependently decreased; whereas the supplementation with highly purified recombinant TN conferred a significant protection. These exciting findings raised several important questions regarding the intricate mechanisms underlying the TN-mediated inhibition of HMGB1 release, as well as its significant protection against LSI. Accordingly, we propose to test: 1) the novel hypothesis that TN divergently regulates HMGB1 release and neutrophil-attracting chemokine expression through distinct mechanisms (Aim 1); 2) the under-appreciated role of TN in LSI by using gene knockout or supplementation with recombinant TN or TN-specific peptide agonists (Aim 2); and 3) the novel mechanisms by which TN or TN-specific peptide agonists affect the outcome of LSI (Aim 3). Collectively, these proposed studies will improve our understanding of the pathophysiology of endotoxemia and sepsis, and help to identify novel therapeutic strategies for the treatment of sepsis and other inflammatory diseases.