Neutrophil extracellular traps promote deep vein thrombosis in mice

J Thromb Haemost. 2012 Jan;10(1):136-44. doi: 10.1111/j.1538-7836.2011.04544.x.

Abstract

Background: Upon activation, neutrophils can release nuclear material known as neutrophil extracellular traps (NETs), which were initially described as a part of antimicrobial defense. Extracellular chromatin was recently reported to be prothrombotic in vitro and to accumulate in plasma and thrombi of baboons with experimental deep vein thrombosis (DVT).

Objective: To explore the source and role of extracellular chromatin in DVT.

Methods: We used an established murine model of DVT induced by flow restriction (stenosis) in the inferior vena cava (IVC).

Results: We demonstrate that the levels of extracellular DNA increase in plasma after 6 h IVC stenosis, compared with sham-operated mice. Immunohistochemical staining revealed the presence of Gr-1-positive neutrophils in both red (RBC-rich) and white (platelet-rich) parts of thrombi. Citrullinated histone H3 (CitH3), an element of NETs' structure, was present only in the red part of thrombi and was frequently associated with the Gr-1 antigen. Immunofluorescent staining of thrombi showed proximity of extracellular CitH3 and von Willebrand factor (VWF), a platelet adhesion molecule crucial for thrombus development in this model. Infusion of Deoxyribonuclease 1 (DNase 1) protected mice from DVT after 6 h and also 48 h IVC stenosis. Infusion of an unfractionated mixture of calf thymus histones increased plasma VWF and promoted DVT early after stenosis application.

Conclusions: Extracellular chromatin, likely originating from neutrophils, is a structural part of a venous thrombus and both the DNA scaffold and histones appear to contribute to the pathogenesis of DVT in mice. NETs may provide new targets for DVT drug development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromatin
  • DNA
  • Histones
  • Mice
  • Neutrophils / metabolism*
  • Vena Cava, Inferior / pathology
  • Venous Thrombosis / etiology*
  • Venous Thrombosis / pathology
  • von Willebrand Factor

Substances

  • Chromatin
  • Histones
  • von Willebrand Factor
  • DNA