Jonathan R Swanson1, Tamas Jilling2, Jing Lu2, Jessica B Landseadel3, Marek Marcinkiewicz3, Phillip V Gordon4. 1. Division of Neonatology, Goryeb Children's Hospital, Morristown, NJ. 2. Department of Pediatrics, Evanston Northwestern Healthcare Research Institute, Evanston, IL. 3. Department of Pediatrics, University of Virginia Children's Hospital, Charlottesville, VA. 4. Department of Pediatrics, Tulane University, New Orleans, LA.
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. HYPOTHESIS: 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 H2O2 and 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.
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. HYPOTHESIS: 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 H2O2 and 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.
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