Complement and coagulation in B. anthracis peptidoglycan-induced sepsis

项目摘要 我们的工作表明，肽聚糖（PGN），细胞壁的主要成分，所有革兰氏阳性 细菌，促进炎症和凝血。狒狒对体内PGN挑战的反应具有以下特征 全身性炎症和弥散性血管内凝血（DIC）与患者中观察到的相似 吸入性炭疽热我们发现了内源性和外源性凝血激活的证据 途径。在体外，我们发现PGN刺激了人类先天免疫细胞中细胞因子的产生， 暴露于来源于B的高度纯化的聚合PGN的人血小板中的凝血酶原酶活性。炭疽 或金黄色葡萄球菌。先天性免疫细胞应答需要PGN被表面Fcγ受体识别， 吞噬作用、溶酶体消化和细胞质NOD传感器刺激。在上一次迭代中， 格兰特，我们表明这些过程依赖于人血清调理素，IgG和血清淀粉样蛋白P。 我们还发现，PGN刺激的人单核细胞表达组织因子（TF），这是一种启动因子， 外源性凝血途径，部分是由于促炎细胞因子。 该项目将提供对PGN刺激的病理学的机理见解。首先，我们将测试 炭疽毒素如何影响免疫系统激活事件，我们已经记录到目前为止，并列出 以上其次，我们将确定调节PGN诱导的内源性凝血激活的途径， 体内途径。最后，我们将把现有的生物抑制剂应用于每一个途径（内在的，外在的 凝血和补体）来询问这些中的哪一个对病理学、器官衰竭和死亡贡献最大 在PGN激发的动物中。这些结果将极大地为革兰氏阳性患者的治疗选择提供信息。 菌血症

Project Summary Our work demonstrates that peptidoglycan (PGN), a major component of the cell wall of all Gram-positive bacteria, promotes inflammation and coagulation. Baboons responded to in vivo PGN challenge with features of systemic inflammation and disseminated intravascular coagulopathy (DIC) similar to those seen in patients with inhalation anthrax. We found evidence of activation of both the intrinsic and extrinsic coagulation pathways. In vitro, we found PGN stimulated robust cytokine production in human innate immune cells and prothrombinase activity in human platelets exposed to highly purified polymeric PGN derived from B. anthracis or Staphylococcus aureus. Innate immune cell responses required PGN recognition by surface Fcγ receptors, phagocytosis, digestion in lysosomes, and stimulation of cytoplasmic NOD sensors. In the last iteration of this grant, we showed that these processes were dependent on human serum opsonins, IgG and serum amyloid P. We also showed that PGN-stimulated human monocytes expressed tissue factor (TF), an initiator of the extrinsic coagulation pathway, in part by virtue of the proinflammatory cytokines. This project will provide mechanistic insight into PGN-stimulated pathologies. First, we will test whether and how the anthrax toxins affect the immune system activation events we have documented to date and listed above. Second, we will identify the pathways that regulate PGN-induced activation of the intrinsic coagulation pathway in vivo. Lastly, we will apply existing biological inhibitors to each pathway (intrinsic, extrinsic coagulation and complement) to ask which of these contributes most to the pathology, organ failure and death in PGN-challenged animals. The results will greatly inform treatment options for patients with Gram-positive bacteremia.