title: Chitin-binding domains of Escherichia coli ChiA mediate interactions with intestinal epithelial cells in mice with colitis.
abstract: OBJECTIVE
  Inducible chitinase 3-like-1 is expressed by intestinal epithelial cells (IECs) and adheres to bacteria under conditions of inflammation. We performed a structure-function analysis of the chitin-binding domains encoded by the chiA gene, which mediates the pathogenic effects of adherent invasive Escherichia coli (AIEC).
  
  
  METHODS
  We created AIEC (strain LF82) with deletion of chiA (LF82-ΔchiA) or that expressed chiA with specific mutations. We investigated the effects of infecting different IEC lines with these bacteria compared with nonpathogenic E coli; chitinase activities were measured using the colloidal chitin-azure method. Colitis was induced in C57/Bl6 mice by administration of dextran sodium sulfate, and mice were given 10(8) bacteria for 15 consecutive days by gavage. Stool/tissue samples were collected and analyzed.
  
  
  RESULTS
  LF82-ΔchiA had significantly less adhesion to IEC lines than LF82. Complementation of LF82-ΔchiA with the LF82 chiA gene, but not chiA from nonpathogenic (K12) E coli, increased adhesion. We identified 5 specific polymorphisms in the chitin-binding domain of LF82 chiA (at amino acids 362, 370, 378, 388, and 548) that differ from chiA of K12 and were required for LF82 to interact directly with IECs. This interaction was mediated by an N-glycosylated asparagine in chitinase 3-like-1 (amino acid 68) on IECs. Mice infected with LF82, or LF82-ΔchiA complemented with LF82 chiA, developed more severe colitis after administration of dextran sodium sulfate than mice infected with LF82-ΔchiA or LF82 that expressed mutant forms of chiA.
  
  
  CONCLUSIONS
  AIEC adheres to an N-glycosylated chitinase 3-like-1 on IECs via the chitin-binding domain of chiA. This mechanism promotes the pathogenic effects of AIEC in mice with colitis.
authors.affiliation: Department of Medicine, Harvard Medical School, Boston, MA, USA.
authors.forename: Daren
authors.initials: D
authors.lastname: Low
authors.forename: Hoa T
authors.initials: HT
authors.lastname: Tran
authors.forename: In-Ah
authors.initials: IA
authors.lastname: Lee
authors.forename: Nicolas
authors.initials: N
authors.lastname: Dreux
authors.forename: Alan
authors.initials: A
authors.lastname: Kamba
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Reinecker
authors.forename: Arlette
authors.initials: A
authors.lastname: Darfeuille-Michaud
authors.forename: Nicolas
authors.initials: N
authors.lastname: Barnich
authors.forename: Emiko
authors.initials: E
authors.lastname: Mizoguchi
mesh_terms: D018830:Adhesins, Escherichia coli / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D000071451:Chitinase-3-Like Protein 1; D002688:Chitinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003092:Colitis / Q000139:chemically induced / Q000201:enzymology / Q000382:microbiology*; D016264:Dextran Sulfate; D004847:Epithelial Cells / Q000201:enzymology / Q000382:microbiology*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000201:enzymology / Q000382:microbiology; D006023:Glycoproteins / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000201:enzymology / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011110:Polymorphism, Genetic
chemical_list: D018830:Adhesins, Escherichia coli; D015415:Biomarkers; C509289:Chil1 protein, mouse; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D016264:Dextran Sulfate; D002688:Chitinases; C094590:chitinase ChiA
keywords: AIEC; Bacterial Infection; CBD; CD; CHI3L1; Crohn's disease; DSS; IBD; IEC; IFN; IL; LP; Mouse Model; TNF; Ulcerative Colitis; WT; adherent-invasive Escherichia coli; chitin-binding domain; chitinase 3-like-1; dextran sulfate sodium; inflammatory bowel disease; interferon; interleukin; intestinal epithelial cell; lamina propria; tumor necrosis factor; wild type