Complement and coagulation in B. anthracis peptidoglycan-induced sepsis

项目摘要 我们的工作表明，所有革兰氏阳性菌细胞壁的主要成分--肽聚糖(PGN) 细菌，促进炎症和凝血。狒狒用特征回应体内PGN挑战 与患者相似的全身炎症和播散性血管内凝血(DIC) 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。 小路。在体外，我们发现PGN刺激人类先天免疫细胞产生强大的细胞因子，并 高纯度炭疽菌多聚体PGN对人血小板凝血酶原酶活性的影响 或者是金黄色葡萄球菌。先天免疫细胞反应需要表面Fcγ受体识别Pgn， 吞噬、溶酶体的消化和胞质结节感受器的刺激。在此的最后一次迭代中 Grant，我们发现这些过程依赖于人血清调理素、免疫球蛋白G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 外源性凝血途径，部分是通过促炎细胞因子实现的。 这个项目将提供对PGN刺激的病理的机械性洞察。首先，我们将测试是否和 炭疽毒素如何影响免疫系统激活事件，我们已经记录并列出了 上面。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，我们将对每一种途径(内在的、外在的)应用现有的生物抑制剂 凝血和补体)，以询问其中哪一项对病理、器官衰竭和死亡的贡献最大 在受到PGN挑战的动物身上。这一结果将极大地指导革兰氏阳性患者的治疗选择 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.