title: Depletion of neutrophil extracellular traps in vivo results in hypersusceptibility to polymicrobial sepsis in mice.
abstract: BACKGROUND
  Although the formation of neutrophil (PMN) extracellular traps (NETs) has been detected during infection and sepsis, their role in vivo is still unclear. This study was performed in order to evaluate the influence of NETs depletion by administration of recombinant human (rh)DNase on bacterial spreading, PMN tissue infiltration and inflammatory response in a mouse model of polymicrobial sepsis.
  
  
  METHODS
  In a prospective controlled double-armed animal trial, polymicrobial sepsis was induced by cecal ligation and puncture (CLP). After CLP, mice were treated with rhDNase or phosphate buffered saline, respectively. Survival, colony forming unit (CFU) counts in the peritoneal cavity, lung, liver and blood were determined. PMN and platelet counts, IL-6 and circulating free (cf)-DNA/NETs levels were monitored. PMN infiltration, as well as organ damage, was analyzed histologically in the lungs and liver. Capability and capacity of PMN to form NETs were determined over time.
  
  
  RESULTS
  cf-DNA/NETs were found to be significantly increased 6, 24, and 48 hours after CLP when compared to the levels determined in sham and naïve mice. Peak levels after 24 hours were correlated to enhanced capacity of bone marrow-derived PMN to form NETs after ex vivo stimulation with phorbol-12-myristate-13-acetate at the same time. rhDNase treatment of mice resulted in a significant reduction of cf-DNA/NETs levels 24 hours after CLP (P < 0.001). Although overall survival was not affected by rhDNase treatment, median survival after 24 hours was significantly lower when compared with the CLP group (P < 0.01). In mice receiving rhDNase treatment, CFU counts in the lung (P < 0.001) and peritoneal cavity (P < 0.05), as well as serum IL-6 levels (P < 0.001), were found to be already increased six hours after CLP. Additionally, enhanced PMN infiltration and tissue damage in the lungs and liver were found after 24 hours. In contrast, CFU counts in mice without rhDNase treatment increased later but more strongly 24 hours after CLP (P < 0.001). Similarly, serum IL-6 levels peaked after 24 hours (P < 0.01).
  
  
  CONCLUSIONS
  This study shows, for the first time, that depletion of NETs by rhDNase administration impedes the early immune response and aggravates the pathology that follows polymicrobial sepsis in vivo.
authors: Wei
authors: W
authors: Meng
authors: Adnana
authors: A
authors: Paunel-Görgülü
authors: Sascha
authors: S
authors: Flohé
authors: Almuth
authors: A
authors: Hoffmann
authors: Ingo
authors: I
authors: Witte
authors: Colin
authors: C
authors: MacKenzie
authors: Stephan E
authors: SE
authors: Baldus
authors: Joachim
authors: J
authors: Windolf
authors: Tim T
authors: TT
authors: Lögters
mesh_terms: D000818:Animals; D058491:Bacterial Load; D003850:Deoxyribonuclease I / Q000494:pharmacology*; D004195:Disease Models, Animal; D018450:Disease Progression; D004198:Disease Susceptibility; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D015850:Interleukin-6 / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D020556:Neutrophil Infiltration / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D011446:Prospective Studies; D011994:Recombinant Proteins / Q000494:pharmacology; D018805:Sepsis / Q000188:drug therapy* / Q000276:immunology* / Q000382:microbiology
chemical_list: D015850:Interleukin-6; D011994:Recombinant Proteins; D003850:Deoxyribonuclease I; C568813:dornase alfa