Isolation of flagellated bacteria implicated in Crohn's disease.
BACKGROUND
Serologic expression cloning has identified flagellins of the intestinal microbiota as immunodominant antigens in experimental colitis in mice and in individuals with Crohn's disease (CD). The present study was done to identify the microbial source of such flagellins.


METHODS
Using a variety of isolation and culture approaches, a number of previously unknown flagellated bacteria were isolated. Based on 16S ribosomal DNA sequences, these bacteria fall into the family Lachnospiraceae of the phylum Firmicutes.


RESULTS
Serum IgG from patients with CD and from mice with colitis reacted to the flagellins of these bacteria, and only their flagellins, whereas serum IgG from controls did not. The sequence of these flagellins demonstrate conserved amino- and carboxy-terminal domains that cluster phylogenetically and have a predicted 3D structure similar to Salmonella fliC, including an intact TLR5 binding site. The flagellin of 1 of these bacteria was likely O-glycosylated.


CONCLUSIONS
The conserved immune response in both mouse and human to these previously unknown flagellins of the microbiota indicate that they play an important role in host-microbe interactions in the intestine.
Duck
L Wayne
LW
Division of Gastroenterology and Hepatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0007, USA.
Walter
Mark R
MR
Novak
Jan
J
Kelly
Denise
D
Tomasi
Maurizio
M
Cong
Yingzi
Y
Elson
Charles O
CO
D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D001419:Bacteria / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D002432:Cecum / Q000382:microbiology*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003424:Crohn Disease / Q000209:etiology* / Q000235:genetics / Q000276:immunology; D004269:DNA, Bacterial / Q000235:genetics*; D005260:Female; D005408:Flagellin / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology; D051379:Mice; D008809:Mice, Inbred C3H; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011817:Rabbits; D017422:Sequence Analysis, DNA
D000942:Antigens, Bacterial; D004269:DNA, Bacterial; D005408:Flagellin