title: Mitochondrial DNA neutrophil extracellular traps are formed after trauma and subsequent surgery.
abstract: BACKGROUND
  Neutrophil extracellular traps (NETs) have not been demonstrated after trauma and subsequent surgery. Neutrophil extracellular traps are formed from pure mitochondrial DNA (mtDNA) under certain conditions, which is potently proinflammatory. We hypothesized that injury and orthopedic trauma surgery would induce NET production with mtDNA as a structural component.
  
  
  METHODS
  Neutrophils were isolated 8 trauma patients requiring orthopedic surgery postinjury and up to 5 days postoperatively. Four healthy volunteers provided positive and negative controls. Total hip replacement patients acted as an uninjured surgical control group. Neutrophil extracellular traps were visualized with DNA (Hoechst 33342TM/Sytox Green/MitoSox/MitoTracker) stains using live cell fluorescence microscopy with downstream quantitative polymerase chain reaction analysis of DNA composition.
  
  
  RESULTS
  Neutrophil extracellular traps were present after injury in all 8 trauma patients. They persisted for 5 days postoperatively. Delayed surgery resulted in NET resolution, but they reformed postoperatively. Total hip replacement patients developed NETs postoperatively, which resolved by day 5. Quantitative polymerase chain reaction analysis of NET-DNA composition revealed that NETs formed after injury and surgery were made of mtDNA with no detectable nuclear DNA component.
  
  
  CONCLUSIONS
  Neutrophil extracellular traps formed after major trauma and subsequent surgery contain mtDNA and represent a novel marker of heightened innate immune activation. They could be considered when timing surgery after trauma to prevent systemic NET-induced inflammatory complications.
authors.affiliation: Department of Traumatology, University of Newcastle, NSW 2310, Australia.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: McIlroy
authors.affiliation: Centre for Asthma and Respiratory Disease & School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Newcastle, NSW 2305, Australia.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Jarnicki
authors.affiliation: Centre for Asthma and Respiratory Disease & School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Newcastle, NSW 2305, Australia.
authors.forename: Gough G
authors.initials: GG
authors.lastname: Au
authors.affiliation: Department of Traumatology, John Hunter Hospital and University of Newcastle, Newcastle, NSW 2310, Australia.
authors.forename: Natalie
authors.initials: N
authors.lastname: Lott
authors.affiliation: Centre for Translational Neuroscience and Mental Health Research, School of Biomedical Sciences and Pharmacy, University of Newcastle, and Hunter Medical Research Institute, Newcastle, NSW 2305, Australia.
authors.forename: Doug W
authors.initials: DW
authors.lastname: Smith
authors.affiliation: Centre for Asthma and Respiratory Disease & School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Newcastle, NSW 2305, Australia.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Hansbro
authors.affiliation: Department of Traumatology, John Hunter Hospital and University of Newcastle, Newcastle, NSW 2310, Australia. Electronic address: zsolt.balogh@hnehealth.nsw.gov.au.
authors.forename: Zsolt J
authors.initials: ZJ
authors.lastname: Balogh
mesh_terms: D000328:Adult; D019644:Arthroplasty, Replacement, Hip; D016470:Bacteremia / Q000276:immunology; D016022:Case-Control Studies; D004272:DNA, Mitochondrial / Q000032:analysis*; D065206:Extracellular Traps / Q000235:genetics*; D050723:Fractures, Bone / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D009504:Neutrophils; D018746:Systemic Inflammatory Response Syndrome / Q000276:immunology; D014947:Wounds and Injuries / Q000276:immunology
chemical_list: D004272:DNA, Mitochondrial
keywords: Mitochondrial DNA neutrophil extracellular traps; Multiple organ failure; NETosis; Trauma