Norovirus triggered microbiota-driven mucosal inflammation in interleukin 10-deficient mice.
BACKGROUND
Infection may trigger clinically overt mucosal inflammation in patients with predisposition for inflammatory bowel disease. However, the impact of particular enteropathogenic microorganisms is ill-defined. In this study, the influence of murine norovirus (MNV) infection on clinical, histopathological, and immunological features of mucosal inflammation in the IL10-deficient (Il10) mouse model of inflammatory bowel disease was examined.


METHODS
C57BL/6J and C3H/HeJBir wild-type and Il10 mice kept under special pathogen-free conditions and devoid of clinical and histopathological signs of mucosal inflammation were monitored after MNV infection for structural and functional intestinal barrier changes by in situ MNV reverse transcription PCR, transgene reporter gene technology, histology, flux measurements, quantitative real-time PCR, immunohistology, and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. In addition, the influence of the enteric microbiota was analyzed in MNV-infected germfree Il10 mice.


RESULTS
Although MNV-infected wild-type mice remained asymptomatic, mucosal inflammation was noted in previously healthy Il10 mice 2 to 4 weeks after infection. MNV-induced changes in Il10 mice included increased paracellular permeability indicated by increased mucosal mannitol flux, reduced gene expression of tight junction molecules, and an enhanced rate of epithelial apoptosis. MNV-induced reduction of tight junction protein expression and inflammatory lesions were absent in germfree Il10 mice, whereas epithelial apoptosis was still observed.


CONCLUSIONS
Despite its subclinical course in wild-type animals, MNV causes epithelial barrier disruption in Il10 animals representing a potent colitogenic stimulus that largely depends on the presence of the enteric microbiota. MNV might thus trigger overt clinical disease in individuals with a nonsymptomatic predisposition for inflammatory bowel disease by impairment of the intestinal mucosa.
*Institute of Laboratory Animal Science, Hannover Medical School, Hannover, Germany; †BioDoc, Hannover, Germany; ‡Department of Physiology, University of Veterinary Medicine Hannover, Hannover, Germany; §Institute for Clinical Biochemistry, Hannover Medical School, Hannover, Germany; ‖Medical Clinic 1, Friedrich-Alexander-University Erlangen-Nuernberg, Erlangen, Germany; ¶Institute of Pharmacology, Hannover Medical School, Hannover, Germany; **Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany; and ††Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany.
Marijana
M
Basic
Lydia M
LM
Keubler
Manuela
M
Buettner
Marcel
M
Achard
Gerhard
G
Breves
Bernd
B
Schröder
Anna
A
Smoczek
Anne
A
Jörns
Dirk
D
Wedekind
Nils H
NH
Zschemisch
Claudia
C
Günther
Detlef
D
Neumann
Stefan
S
Lienenklaus
Siegfried
S
Weiss
Mathias W
MW
Hornef
Michael
M
Mähler
André
A
Bleich
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D017250:Caliciviridae Infections / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D007249:Inflammation / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D016753:Interleukin-10 / Q000502:physiology*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D064307:Microbiota; D052016:Mucositis / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D029322:Norovirus / Q000472:pathogenicity*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D016207:Cytokines; D012333:RNA, Messenger; D016753:Interleukin-10