Autophagy mediates the delivery of thrombogenic tissue factor to neutrophil extracellular traps in human sepsis

PLoS One. 2012;7(9):e45427. doi: 10.1371/journal.pone.0045427. Epub 2012 Sep 19.


Background: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy / drug effects
  • Autophagy / physiology*
  • Cells, Cultured
  • Humans
  • Macrolides / pharmacology
  • Neutrophils / metabolism*
  • Phosphatidylinositol 3-Kinase / metabolism
  • Phosphoinositide-3 Kinase Inhibitors
  • Protein Transport / drug effects
  • Protein Transport / physiology
  • Sepsis / metabolism*
  • Thromboplastin / metabolism*


  • Macrolides
  • Phosphoinositide-3 Kinase Inhibitors
  • bafilomycin A1
  • Thromboplastin
  • Phosphatidylinositol 3-Kinase

Grant support

This study was supported by the Hellenic Ministry of Education and General Secretariat for Research and Technology (ESPA project/No 898). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.