title: Promotion of hypercoagulability in antineutrophil cytoplasmic antibody-associated vasculitis by C5a-induced tissue factor-expressing microparticles and neutrophil extracellular traps.
abstract: OBJECTIVE
  Patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV) have a high frequency of venous thromboembolic events and a hypercoagulable state. As C5a-primed neutrophils play an important role in the development of AAV, we investigated whether C5a-induced neutrophil tissue factor (TF)-expressing microparticles (MPs) and neutrophil extracellular traps (NETs) might promote hypercoagulability in AAV.
  
  
  METHODS
  TF-expressing MPs were measured by flow cytometry. TF-expressing NETs were assessed by confocal microscopy. Levels of thrombin-antithrombin complexes were determined by enzyme-linked immunosorbent assay. The effect of C5a in sera from AAV patients was evaluated by treating neutrophils with C5a receptor antagonist before incubation with sera from AAV patients with active disease.
  
  
  RESULTS
  Treatment of C5a-primed neutrophils with antineutrophil cytoplasmic antibody (ANCA)-positive IgG resulted in the release of TF-bearing MPs and NETs. Neutrophils from healthy donors treated with sera from patients with active AAV released TF-bearing MPs and NETs, which were abolished by treatment with C5a receptor antagonist. Involvement of TF in MP- or NET-dependent thrombin generation was indicated by the findings of antibody neutralization studies. NETs with thrombin-generating capacity were demonstrated by DNase I treatment.
  
  
  CONCLUSIONS
  C5a-primed neutrophils produce TF-expressing MPs and NETs after stimulation with ANCAs, indicating a mechanism for hypercoagulability in AAV that was not previously recognized.
authors.affiliation: Peking University First Hospital and Peking University, Beijing, China.
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: Huang
authors.affiliation: Peking University First Hospital and Peking University, Beijing, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Peking University First Hospital and Peking University, Beijing, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.affiliation: Peking University First Hospital and Peking University, Beijing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.affiliation: Peking University First Hospital and Peking University, Beijing, China.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000150:complications* / Q000503:physiopathology; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000494:pharmacology; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000502:physiology*; D002478:Cells, Cultured; D015936:Complement C5a / Q000494:pharmacology / Q000502:physiology*; D065206:Extracellular Traps / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009504:Neutrophils / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D009707:Nucleosomes / Q000502:physiology; D013917:Thrombin / Q000378:metabolism; D019851:Thrombophilia / Q000209:etiology* / Q000503:physiopathology*; D013925:Thromboplastin / Q000502:physiology*
chemical_list: D019268:Antibodies, Antineutrophil Cytoplasmic; D009707:Nucleosomes; D015936:Complement C5a; D013925:Thromboplastin; D013917:Thrombin