title: α-Haemolysin of Escherichia coli in IBD: a potentiator of inflammatory activity in the colon.
abstract: OBJECTIVE
  α-Haemolysin (HlyA) influences host cell ionic homeostasis and causes concentration-dependent cell lysis. As a consequence, HlyA-producing Escherichia coli is capable of inducing 'focal leaks' in colon epithelia, through which bacteria and antigens translocate. This study addressed the role of HlyA as a virulence factor in the pathogenesis of colitis according to the 'leaky gut' concept.
  
  
  METHODS
  To study the action of HlyA in the colon, we performed oral administration of HlyA-expressing E coli-536 and its isogenic α-haemolysin-deficient mutant (HDM) in three mouse models: wild type, interleukin-10 knockout mice (IL-10(-/-)) and monoassociated mice. Electrophysiological properties of the colonised colon were characterised in Ussing experiments. Inflammation scores were evaluated and focal leaks in the colon were assessed by confocal laser-scanning microscopy. HlyA quantity in human colon biopsies was measured by quantitative PCR.
  
  
  RESULTS
  All three experimental mouse models infected with HlyA-producing E coli-536 showed an increase in focal leak area compared with HDM. This was associated with a decrease in transepithelial electrical resistance and an increase in macromolecule uptake. As a consequence, inflammatory activity index was increased to a higher degree in inflammation-prone mice. Mucosal samples from human colon were E coli HlyA-positive in 19 of 22 patients with ulcerative colitis, 9 of 9 patients with Crohn's disease and 9 of 12 healthy controls. Moreover, focal leaks were found together with 10-fold increased levels of HlyA in active ulcerative colitis.
  
  
  CONCLUSIONS
  E coli HlyA impairs intestinal barrier function via focal leak induction in the epithelium, thereby intensifying antigen uptake and triggering intestinal inflammation in vulnerable mouse models. Therefore, HlyA-expressing E coli strains should be considered as potential cofactors in the pathogenesis of intestinal inflammation.
authors.affiliation: Department of Gastroenterology, Infectious Diseases and Rheumatology, Berlin, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Bücker
authors.affiliation: Department of Gastroenterology, Infectious Diseases and Rheumatology, Berlin, Germany.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Schulz
authors.affiliation: Institute of Clinical Physiology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Günzel
authors.affiliation: Department of Gastroenterology, Infectious Diseases and Rheumatology, Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Bojarski
authors.affiliation: Institute of Clinical Physiology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany.
authors.forename: In-Fah M
authors.initials: IF
authors.lastname: Lee
authors.affiliation: Department of Gastroenterology, Infectious Diseases and Rheumatology, Berlin, Germany.
authors.forename: Lena J
authors.initials: LJ
authors.lastname: John
authors.affiliation: Department of Gastroenterology, Infectious Diseases and Rheumatology, Berlin, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Wiegand
authors.affiliation: Department of Veterinary Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany.
authors.forename: Traute
authors.initials: T
authors.lastname: Janßen
authors.affiliation: Department of Veterinary Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany.
authors.forename: Lothar H
authors.initials: LH
authors.lastname: Wieler
authors.affiliation: Institute of Hygiene, University of Münster, Münster, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Dobrindt
authors.affiliation: Bundesinstitut für Risikobewertung, Berlin, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Beutin
authors.affiliation: Department of Veterinary Medicine, Institute of Hygiene and Infectious Diseases of Animals, Justus-Liebig-Universität Giessen, Giessen, Germany.
authors.forename: Christa
authors.initials: C
authors.lastname: Ewers
authors.affiliation: Institute of Clinical Physiology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Fromm
authors.affiliation: Department of Gastroenterology, Infectious Diseases and Rheumatology, Berlin, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Siegmund
authors.affiliation: Department of Gastroenterology, Infectious Diseases and Rheumatology, Berlin, Germany.
authors.forename: Hanno
authors.initials: H
authors.lastname: Troeger
authors.affiliation: Department of Gastroenterology, Infectious Diseases and Rheumatology, Berlin, Germany.
authors.forename: Jörg-Dieter
authors.initials: JD
authors.lastname: Schulzke
mesh_terms: D000818:Animals; D000941:Antigens / Q000378:metabolism*; D003093:Colitis, Ulcerative / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D003424:Crohn Disease / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D004195:Disease Models, Animal; D055724:Electrophysiological Phenomena; D020895:Enterocytes / Q000378:metabolism / Q000473:pathology; D004926:Escherichia coli / Q000378:metabolism / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000378:metabolism*; D006801:Humans; D018928:Immunity, Mucosal; D007249:Inflammation / Q000276:immunology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D010539:Permeability
chemical_list: D000941:Antigens; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli
keywords: Bacterial Enterotoxins; Bacterial Pathogenesis; Epithelial Barrier; Epithelial Permeability; Ulcerative Colitis