First Department of Internal Medicine, Democritus University of Thrace, University General Hospital of Alexandroupolis, Alexandroupolis, Greece.
PLoS One. 2012;7(9):e45427. doi: 10.1371/journal.pone.0045427. Epub 2012 Sep 19.
Sepsis is associated with systemic inflammatory responses and induction of coagulation system. Neutrophil extracellular traps (NETs) constitute an antimicrobial mechanism, recently implicated in thrombosis via platelet entrapment and aggregation.
METHODOLOGY/PRINCIPAL FINDINGS: In this study, we demonstrate for the first time the localization of thrombogenic tissue factor (TF) in NETs released by neutrophils derived from patients with gram-negative sepsis and normal neutrophils treated with either serum from septic patients or inflammatory mediators involved in the pathogenesis of sepsis. Localization of TF in acidified autophagosomes was observed during this process, as indicated by positive LC3B and LysoTracker staining. Moreover, phosphatidylinositol 3-kinase inhibition with 3-MA or inhibition of endosomal acidification with bafilomycin A1 hindered the release of TF-bearing NETs. TF present in NETs induced thrombin generation in culture supernatants, which further resulted in protease activated receptor-1 signaling.
CONCLUSIONS/SIGNIFICANCE: This study demonstrates the involvement of autophagic machinery in the extracellular delivery of TF in NETs and the subsequent activation of coagulation cascade, providing evidence for the implication of this process in coagulopathy and inflammatory response in sepsis.
脓毒症与全身炎症反应和凝血系统的诱导有关。中性粒细胞胞外诱捕网（NETs）构成了一种抗微生物机制，最近通过血小板捕获和聚集被牵连到血栓形成中。
方法/主要发现：在这项研究中，我们首次证明了来源于革兰氏阴性脓毒症患者的中性粒细胞和用脓毒症患者的血清或参与脓毒症发病机制的炎症介质处理的正常中性粒细胞释放的 NETs 中存在血栓形成组织因子（TF）的定位。在这个过程中，观察到 TF 在酸化自噬体中的定位，如 LC3B 和 LysoTracker 染色阳性所示。此外，用 3-MA 抑制磷酸肌醇 3-激酶或用巴弗洛霉素 A1 抑制内体酸化抑制了 TF 携带的 NETs 的释放。NETs 中存在的 TF 在培养上清液中诱导凝血酶生成，这进一步导致蛋白酶激活受体-1 信号转导。
结论/意义：本研究证明了自噬机制在 NETs 中 TF 的细胞外传递中的参与，以及随后凝血级联的激活，为这一过程在脓毒症中的凝血功能障碍和炎症反应中的作用提供了证据。
