Gnotobiotic IL-10-/-;NF-kappa B(EGFP) mice reveal the critical role of TLR/NF-kappa B signaling in commensal bacteria-induced colitis.
Commensal bacteria and TLR signaling have been associated with the maintenance of intestinal homeostasis in dextran sodium sulfate-induced intestinal injury. The aim of this study was to determine the in vivo role of TLR/NF-kappaB activation in a model of commensal bacteria-induced T cell-mediated colitis. A NF-kappaB reporter gene mouse (NF-kappaBEGFP) (EGFP, enhanced GFP) was crossed to the colitogenic susceptible strain IL-10-/- and derived into germfree conditions using embryo-transfer technology. Germfree IL-10wt/wt;NF-kappaBEGFP and IL-10-/-;NF-kappaBEGFP mice (wt, wild type) were dual associated with the nonpathogenic commensal bacteria strains Enterococcus faecalis and Escherichia coli. EGFP was detected using macroimaging, confocal microscopy, and flow cytometry. IL-10-/-;MyD88-/- mice were used to assess E. faecalis/E. coli-induced TLR-dependent signaling and IL-23 gene expression. Dual-associated IL-10-/-;NF-kappaBEGFP mice developed severe inflammation by 7 wk. Macroscopic analysis showed elevated EGFP expression throughout the colon of bacteria-associated IL-10-/-;NF-kappaBEGFP mice. Confocal microscopy analysis revealed EGFP-positive enterocytes during the early phase of bacterial colonization (1 wk) in both IL-10wt/wt and IL-10-/- mice, while the signal shifted toward lamina propria T cells, dendritic cells, neutrophils, and macrophages in IL-10-/- mice during colitis (7 wk). The NF-kappaB inhibitor BAY 11-7085 attenuated E. faecalis/E. coli-induced EGFP expression and development of colitis. Additionally, E. faecalis/E. coli-induced NF-kappaB signaling and IL-23 gene expression were blocked in bone marrow-derived dendritic cells derived from IL-10-/-;MyD88-/- mice. We conclude that bacteria-induced experimental colitis involves the activation of TLR-induced NF-kappaB signaling derived mostly from mucosal immune cells. Blocking TLR-induced NF-kappaB activity may represent an attractive strategy to treat immune-mediated intestinal inflammation.
Karrasch
Thomas
T
Department of Medicine and Center for Gastrointestinal Biology and Disease, University of North Carolina, Chapel Hill, NC 27510, USA.
Kim
Joo-Sung
JS
Muhlbauer
Marcus
M
Magness
Scott T
ST
Jobin
Christian
C
D000818:Animals; D003092:Colitis / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D013293:Enterococcus faecalis / Q000276:immunology; D004927:Escherichia coli Infections / Q000235:genetics / Q000276:immunology / Q000473:pathology; D005260:Female; D017930:Genes, Reporter; D005856:Germ-Free Life / Q000276:immunology*; D016908:Gram-Positive Bacterial Infections / Q000235:genetics / Q000276:immunology / Q000473:pathology; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics*; D016753:Interleukin-10 / Q000172:deficiency* / Q000235:genetics* / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D016328:NF-kappa B / Q000235:genetics* / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D051193:Toll-Like Receptors / Q000502:physiology*
D016328:NF-kappa B; D051193:Toll-Like Receptors; C485184:enhanced green fluorescent protein; D016753:Interleukin-10; D049452:Green Fluorescent Proteins