Article Text
Abstract
Background: Infection with Helicobacter species has been associated with the development of mucosal inflammation and inflammatory bowel disease (IBD) in several mouse models. However, consensus regarding the role of Helicobacter as a model organism to study microbial-induced IBD is confounded by the presence of a complex colonic microbiota.
Aim: To investigate the kinetics and inflammatory effects of immune system activation to commensal bacteria following H bilis colonisation in gnotobiotic mice.
Methods: C3H/HeN mice harbouring an altered Schaedler flora (ASF) were selectively colonised with H bilis and host responses were investigated over a 10-week period. Control mice were colonised only with the defined flora (DF). Tissues were analysed for gross/histopathological lesions, and bacterial antigen-specific antibody and T-cell responses.
Results: Gnotobiotic mice colonised with H bilis developed mild macroscopic and microscopic lesions of typhlocolitis beginning 3 weeks postinfection. ASF-specific IgG responses were demonstrable within 3 weeks, persisted throughout the 10-week study, and presented as a mixed IgG1:IgG2a profile. Lymphocytes recovered from the mesenteric lymph node of H bilis-colonised mice produced increased levels of interferon γ, tumour necrosis factor α (TNFα), interleukin 6 (IL6) and IL12 in response to stimulation with commensal- or H bilis-specific bacterial lysates. In contrast, DF mice not colonised with H bilis did not develop immune responses to their resident flora and remained disease free.
Conclusions: Colonisation of gnotobiotic C3H/HeN mice with H bilis perturbs the host’s response to its resident flora and induces progressive immune reactivity to commensal bacteria that contributes to the development of immune-mediated intestinal inflammation.
- ASF, altered Schaedler flora
- DF, defined flora
- ELISA, enzyme-linked immunosorbent assay
- FBS, fetal bovine serum
- IBD, inflammatory bowel disease
- IFNγ, interferon γ
- IL, interleukin
- MLN, mesenteric lymph node
- NI, non-infected
- PBS, phophate-buffered saline
- PBST, phosphate-buffered saline Tween 20
- PI, postinfection
- SPF, specific pathogen-free
- SPL, spleen
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- ASF, altered Schaedler flora
- DF, defined flora
- ELISA, enzyme-linked immunosorbent assay
- FBS, fetal bovine serum
- IBD, inflammatory bowel disease
- IFNγ, interferon γ
- IL, interleukin
- MLN, mesenteric lymph node
- NI, non-infected
- PBS, phophate-buffered saline
- PBST, phosphate-buffered saline Tween 20
- PI, postinfection
- SPF, specific pathogen-free
- SPL, spleen
Footnotes
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Published Online First 1 December 2006
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Competing interests: None declared.
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Funding: This work was supported by NIH grant KO1 RR 018618 (NCRR).