title: Outside-in? Acute fetal systemic inflammation in very preterm chronically catheterized sheep fetuses is not driven by cells in the fetal blood.
abstract: BACKGROUND
  The preterm birth syndrome (delivery before 37 weeks gestation) is a major contributor to the global burden of perinatal morbidity and death. The cause of preterm birth is complex, multifactorial, and likely dependent, at least in part, on the gestational age of the fetus. Intrauterine infection is frequent in preterm deliveries that occur at <32 weeks gestation; understanding how the fetus responds to proinflammatory insult will be an important step towards early preterm birth prevention. However, animal studies of infection and inflammation in prematurity commonly use older fetuses that possess comparatively mature immune systems.
  
  
  OBJECTIVE
  Aiming to characterize acute fetal responses to microbial agonist at a clinically relevant gestation, we used 92-day-old fetuses (62% of term) to develop a chronically catheterized sheep model of very preterm pregnancy. We hypothesized that any acute fetal systemic inflammatory responses would be driven by signaling from the tissues exposed to Escherichia coli lipopolysaccharide that is introduced into the amniotic fluid.
  
  
  METHODS
  Eighteen ewes that were carrying a single fetus at 92 days of gestation had recovery surgery to place fetal tracheal, jugular, and intraamniotic catheters. Animals were recovered for 24 hours before being administered either intraamniotic E coli lipopolysaccharide (n = 9) or sterile saline solution (n = 9). Samples were collected for 48 hours before euthanasia and necroscopy. Fetal inflammatory responses were characterized by microarray analysis, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Intraamniotic lipopolysaccharide reached the distal trachea within 2 hours. Lipopolysaccharide increased tracheal fluid interleukin-8 within 2 hours and generated a robust inflammatory response that was characterized by interleukin-6 signaling pathway activation and up-regulation of cell proliferation but no increases in inflammatory mediator expression in cord blood RNA.
  
  
  CONCLUSIONS
  In very preterm sheep fetuses, lipopolysaccharide stimulates inflammation in the fetal lung and fetal skin and stimulates a systemic inflammatory response that is not generated by fetal blood cells. These data argue for amniotic fluid-exposed tissues that play a key role in driving acute fetal and intrauterine inflammatory responses.
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia. Electronic address: matthew.kemp@uwa.edu.au.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Kemp
authors.affiliation: Blood, Stem Cells and Cancer Research Programme, St Vincent's Centre for Applied Medical Research, Darlinghurst, NSW, Australia.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Molloy
authors.affiliation: Division of Perinatal Medicine, Tohoku University Hospital, Sendai, Miyagi, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Usuda
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Woodward
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Miura
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Payne
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Demelza J
authors.initials: DJ
authors.lastname: Ireland
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia; Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Centre, University of Cincinnati, School of Medicine, Cincinnati, OH.
authors.forename: Alan H
authors.initials: AH
authors.lastname: Jobe
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia; Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Centre, University of Cincinnati, School of Medicine, Cincinnati, OH.
authors.forename: Suhas G
authors.initials: SG
authors.lastname: Kallapur
authors.affiliation: MRC Centre for Reproductive Health, University of Edinburgh Queen's Medical Research Institute, Edinburgh, UK.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Stock
authors.affiliation: Cardiff University, School of Medicine, Institute of Molecular and Experimental Medicine, University Hospital of Wales, Cardiff, UK.
authors.forename: Owen B
authors.initials: OB
authors.lastname: Spiller
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: John P
authors.initials: JP
authors.lastname: Newnham
authors.affiliation: School of Women's and Infants' Health, The University of Western Australia, Perth, Western Australia, Australia; Division of Perinatal Medicine, Tohoku University Hospital, Sendai, Miyagi, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Saito
mesh_terms: D000653:Amniotic Fluid; D000818:Animals; D002404:Catheterization; D002405:Catheterization, Central Venous; D049109:Cell Proliferation / Q000187:drug effects; D054412:Chemokine CCL8 / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D016207:Cytokines / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli; D005260:Female; D005312:Fetal Blood / Q000276:immunology*; D005315:Fetal Diseases / Q000276:immunology*; D005333:Fetus / Q000187:drug effects* / Q000276:immunology; D007249:Inflammation; D016753:Interleukin-10 / Q000235:genetics / Q000276:immunology; D053583:Interleukin-1beta / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology; D016209:Interleukin-8 / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012333:RNA, Messenger / Q000276:immunology / Q000378:metabolism*; D012756:Sheep; D018746:Systemic Inflammatory Response Syndrome / Q000276:immunology*; D046888:Tissue Array Analysis; D014132:Trachea; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D015854:Up-Regulation
chemical_list: D054412:Chemokine CCL8; D016207:Cytokines; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10
keywords: fetus; infection; inflammation; preterm birth; sheep