title: Neonatal exposure to fecal antigens reduces intestinal inflammation.
abstract: BACKGROUND
  A role for bacterial antigens in the pathogenesis of inflammatory bowel disease (IBD) has been established in enhanced humoral and cellular immune response to ubiquitous antigens of the enteric flora. However, we have recently shown that bacterial antigens in the absence of live bacteria cannot initiate an intestinal inflammation in IBD-prone interleukin (IL)-10 gene-deficient mice. The objective was to investigate whether neonatal exposure to antigens of their own endogenous flora can tolerize mice to bacterial antigens.
  
  
  METHODS
  IL-10 gene-deficient neonates were injected intraperitoneally within 72 hours of birth with a sterile solution of bacterial lysates prepared from fecal material of either conventionally raised mice (contains bacterial antigens) or axenic mice (lacks bacterial antigens). The onset of intestinal inflammation was monitored as the appearance of occult blood in the stool in weekly hemoccult analysis. Mice were sacrificed between age 15 and 19 weeks and tested for histopathologic injury, intestinal inflammation, and systemic response to bacterial antigens.
  
  
  RESULTS
  In mice neonatally exposed to bacterial antigens the onset of intestinal inflammation was delayed and the incidence of histopathologic injury at age 18 weeks was reduced. In addition, mice injected with lysates from conventionally raised mice exhibited decreased release of proinflammatory cytokines (interferon gamma [IFN-γ] and IL-17) in intestinal tissue and demonstrated reduced bacteria-stimulated systemic responses when compared to mice injected with lysates derived from bacteria-free, axenic mice.
  
  
  CONCLUSIONS
  Neonatal intraperitoneal injection of antigens from the commensal flora causes long-lasting changes in systemic and mucosal immune responses resulting in delayed onset of intestinal inflammation and injury in IBD-prone IL-10 gene-deficient mice.
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of Alberta, Center of Excellence for Gastrointestinal Inflammation and Immunity Research, Edmonton, Alberta, Canada. bsydora@ualberta.ca
authors.forename: Beate C
authors.initials: BC
authors.lastname: Sydora
authors.forename: Sarah M
authors.initials: SM
authors.lastname: McFarlane
authors.forename: Jason S G
authors.initials: JS
authors.lastname: Doyle
authors.forename: Richard N
authors.initials: RN
authors.lastname: Fedorak
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000942:Antigens, Bacterial / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000737:chemistry* / Q000382:microbiology; D007111:Immunity, Cellular; D007249:Inflammation / Q000276:immunology / Q000517:prevention & control*; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000502:physiology*; D020381:Interleukin-17 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013154:Spleen / Q000276:immunology / Q000382:microbiology / Q000473:pathology
chemical_list: D000942:Antigens, Bacterial; D020381:Interleukin-17; D016753:Interleukin-10; D007371:Interferon-gamma