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. DESIGN: 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. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
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. DESIGN: 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. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Authors: Trudy M Wassenaar; Anke Zschüttig; Claudia Beimfohr; Thomas Geske; Christian Auerbach; Helen Cook; Kurt Zimmermann; Florian Gunzer Journal: Eur J Microbiol Immunol (Bp) Date: 2015-03-26
Authors: R Bücker; S M Krug; V Moos; C Bojarski; M R Schweiger; M Kerick; A Fromm; S Janßen; M Fromm; N A Hering; B Siegmund; T Schneider; C Barmeyer; J D Schulzke Journal: Mucosal Immunol Date: 2017-08-02 Impact factor: 7.313