title: Neutrophil Extracellular Traps in the Amniotic Cavity of Women with Intra-Amniotic Infection: A New Mechanism of Host Defense.
abstract: Neutrophil extracellular traps (NETs) control microbial infections through their antimicrobial activities attributed to DNA, histones, granules, and cytoplasmic proteins (eg, elastase). Intra-amniotic infection is characterized by the influx of neutrophils into the amniotic cavity; therefore, the aim of this study was to determine whether amniotic fluid neutrophils form NETs in this inflammatory process.
  
  
  
  Amniotic fluid samples from women with intra-amniotic infection (n = 15) were stained for bacteria detection using fluorescent dyes. Amniotic fluid neutrophils were purified by filtration. As controls, neutrophils from maternal blood samples (n = 3) were isolated by density gradients. Isolated neutrophils were plated onto glass cover slips for culture with and without 100 nM of phorbol-12-myristate-13-acetate (PMA). NET formation was assessed by 4',6-diamidino-2-phenylindole (DAPI) staining and scanning electron microscopy. Different stages of NET formation were visualized using antibodies against elastase and histone H3, in combination with DAPI staining, by confocal microscopy. Finally, maternal or neonatal neutrophils were added to amniotic fluid samples from women without intra-amniotic infection (n = 4), and NET formation was evaluated by DAPI staining.
  
  
  
  (1) NETs were present in the amniotic fluid of women with intra-amniotic infection; (2) all of the amniotic fluid samples had detectable live and dead bacteria associated with the presence of NETs; (3) in contrast to neutrophils from the maternal circulation, amniotic fluid neutrophils did not require PMA stimulation to form NETs; (4) different stages of NET formation were observed by co-localizing elastase, histone H3, and DNA in amniotic fluid neutrophils; and (5) neither maternal nor neonatal neutrophils form NETs in the amniotic fluid of women without intra-amniotic infection.
  
  
  
  NETs are detectable in the amniotic fluid of women with intra-amniotic infection.
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|2 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.|3 Department of Immunology and Microbiology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Nardhy
authors.initials: N
authors.lastname: Gomez-Lopez
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|4 Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI, USA.|5 Department of Epidemiology and Biostatistics, Michigan State University, East Lansing, MI, USA.|6 Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, USA.
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|2 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|2 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.|3 Department of Immunology and Microbiology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Derek
authors.initials: D
authors.lastname: Miller
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|2 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Ronald
authors.initials: R
authors.lastname: Unkel
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|2 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Majid
authors.initials: M
authors.lastname: Shaman
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|7 Department of Pathology, Hutzel Women's Hospital/Harper University Hospital, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Jacques
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|2 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Panaitescu
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|2 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Valeria
authors.initials: V
authors.lastname: Garcia-Flores
authors.affiliation: 1 Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, USA and Detroit, MI, USA.|2 Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Hassan
mesh_terms: D000328:Adult; D000650:Amnion / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D000653:Amniotic Fluid / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D001424:Bacterial Infections / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D065206:Extracellular Traps / Q000378:metabolism*; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism*; D011247:Pregnancy; D055815:Young Adult
chemical_list: D015850:Interleukin-6
keywords: cytokines; fetal inflammatory response; fever; funisitis; inflammation; intra-amniotic inflammation; labor; microbial invasion of the amniotic cavity (MIAC); neutrophil; parturition; pregnancy; preterm birth; preterm labor