title: Ileal Immunoglobulin Binding by the Neonatal Fc Receptor: A Previously Unrecognized Mechanism of Protection in the Neonatal Rat Model of Necrotizing Enterocolitis?
abstract: BACKGROUND
  Mucosal apoptosis is the initiating event in models of necrotizing enterocolitis (NEC) within rodents. It is possible there are species-specific differences that make apoptosis a more prominent feature of NEC in rodents than in humans.
  
  
  OBJECTIVE
  A lower threshold for mucosal apoptosis in the rodent distal intestine might have evolutionary advantages (via enhanced opsonization with the neonatal Fc receptor [FcRn]), since many short-gestation mammals are comparatively premature (histomorphologically) but are protected from NEC by breast milk.
  
  
  METHODS
  We utilized a rat intestinal epithelial cell (IEC-18) model to determine if cell death alters FcRn - IgG binding, and rodent models of NEC to determine if cell death results in increased opsonization of IgG. Cultured IEC-18 cells were treated with H2O2and analyzed. Neonatal Sprague-Dawley rats were cold and hypoxia stressed and intestinal sections were frozen for analysis.
  
  
  RESULTS
  IgG binding was increased in H2O2-treated cells. Co-incubation of treated cells with either insulin-like growth factor or tunicamycin decreased IgG binding. Sprague-Dawley rats formula fed with exogenous bacteria showed a significant decrease in intestinal FcRn mRNA but increased ileal IgG binding.
  
  
  CONCLUSIONS
  We speculate that FcRn plays a role in passive opsonization and subsequent bacterial pathogen clearance, making rodents resistant to NEC.
authors.affiliation: Division of Neonatology, Goryeb Children's Hospital, Morristown, NJ.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Swanson
authors.affiliation: Department of Pediatrics, Evanston Northwestern Healthcare Research Institute, Evanston, IL.
authors.forename: Tamas
authors.initials: T
authors.lastname: Jilling
authors.affiliation: Department of Pediatrics, Evanston Northwestern Healthcare Research Institute, Evanston, IL.
authors.forename: Jing
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Pediatrics, University of Virginia Children's Hospital, Charlottesville, VA.
authors.forename: Jessica B
authors.initials: JB
authors.lastname: Landseadel
authors.affiliation: Department of Pediatrics, University of Virginia Children's Hospital, Charlottesville, VA.
authors.forename: Marek
authors.initials: M
authors.lastname: Marcinkiewicz
authors.affiliation: Department of Pediatrics, Tulane University, New Orleans, LA.
authors.forename: Phillip V
authors.initials: PV
authors.lastname: Gordon
keywords: glycosylation; immunoglobulin; intestinal epithelial cell; necrotizing enterocolitis; neonatal Fc receptor
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