title: Histologic Findings and Inflammatory Reactions After Long-term Colonization of Helicobacter felis in C57BL/6 Mice.
abstract: BACKGROUND
  The Helicobacter felis (H. felis) mouse model has been developed for the research regarding pathogenesis of chronic gastritis and gastric cancer. The aim of this study was to investigate long-term H. felis colonization in the stomachs of C57BL/6 mice and subsequent histologic findings and inflammatory reactions including pro-inflammatory cytokines.
  
  
  METHODS
  Twenty-three female C57BL/6 mice at 4 weeks of age were gavaged with H. felis, and 13 control mice served as vehicle only. The mice were sacrificed at 4, 24, and 52 weeks after inoculation. The infection status and degree of inflammation were determined by culture and histopathology. The level of gastric mucosal myeloperoxidase (MPO), tumor necrosis factor alpha (TNF-α), and interleukin-1beta (IL-1β) were measured by ELISA.
  
  
  RESULTS
  The overall infection rate was 100%, as determined by the culture and histology. At 4, 24, and 52 weeks, the neutrophil and monocyte scores were significantly higher in infected mice than in control mice. At 24 weeks after inoculation, most of the infected mice showed mucosal atrophy with or without metaplasia, and a few showed focal dysplasia. Adenocarcinoma was observed in one mouse at 52 week post-infection. Gastric mucosal MPO and IL-1β levels were significantly higher in infected mice than those in control mice at 24 and 52 weeks. However, the expression of gastric mucosal TNF-α was not significantly different between the infected and control mice at any time-point.
  
  
  CONCLUSIONS
  Long-term H. felis-infection in C57BL/6 mice provoked a severe inflammatory reaction and it progressed into atrophy, metaplasia, dysplasia and cancer. IL-1β might play an important role in the inflammatory response of mice to Helicobacter species.
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Ju Yup
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Nayoung
authors.initials: N
authors.lastname: Kim
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Yoon Jeong
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Ryoung Hee
authors.initials: RH
authors.lastname: Nam
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Yoon Jin
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Yong Hwan
authors.initials: YH
authors.lastname: Kwon
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Kichul
authors.initials: K
authors.lastname: Yoon
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Ji Hyung
authors.initials: JH
authors.lastname: Suh
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Seon Min
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Pathology, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Hye Seung
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Departments of Internal Medicine, Seoul National University Bundang Hospital, Seoungnam, Korea.
authors.forename: Dong Ho
authors.initials: DH
authors.lastname: Lee
keywords: Helicobacter felis; Inflammation; Interleukin-1beta; Tumor necrosis factor-alpha