title: Enterohemorrhagic Escherichia coli colonization of human colonic epithelium in vitro and ex vivo.
abstract: Enterohemorrhagic Escherichia coli (EHEC) is an important foodborne pathogen causing gastroenteritis and more severe complications, such as hemorrhagic colitis and hemolytic uremic syndrome. Pathology is most pronounced in the colon, but to date there is no direct clinical evidence showing EHEC binding to the colonic epithelium in patients. In this study, we investigated EHEC adherence to the human colon by using in vitro organ culture (IVOC) of colonic biopsy samples and polarized T84 colon carcinoma cells. We show for the first time that EHEC colonizes human colonic biopsy samples by forming typical attaching and effacing (A/E) lesions which are dependent on EHEC type III secretion (T3S) and binding of the outer membrane protein intimin to the translocated intimin receptor (Tir). A/E lesion formation was dependent on oxygen levels and suppressed under oxygen-rich culture conditions routinely used for IVOC. In contrast, EHEC adherence to polarized T84 cells occurred independently of T3S and intimin and did not involve Tir translocation into the host cell membrane. Colonization of neither biopsy samples nor T84 cells was significantly affected by expression of Shiga toxins. Our study suggests that EHEC colonizes and forms stable A/E lesions on the human colon, which are likely to contribute to intestinal pathology during infection. Furthermore, care needs to be taken when using cell culture models, as they might not reflect the in vivo situation.
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, United Kingdom Gut Health and Food Safety Programme, Institute of Food Research, Norwich, United Kingdom.
authors.forename: Steven B
authors.initials: SB
authors.lastname: Lewis
authors.affiliation: Gastroenterology Department, Norfolk and Norwich University Hospital, Norwich, United Kingdom.
authors.forename: Vivienne
authors.initials: V
authors.lastname: Cook
authors.affiliation: Gastroenterology Department, Norfolk and Norwich University Hospital, Norwich, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: Tighe
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich, United Kingdom Gut Health and Food Safety Programme, Institute of Food Research, Norwich, United Kingdom stephanie.schuller@ifr.ac.uk.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schüller
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics* / Q000378:metabolism; D001422:Bacterial Adhesion; D045744:Cell Line, Tumor; D003106:Colon / Q000382:microbiology / Q000473:pathology; D019453:Escherichia coli O157 / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology* / Q000473:pathology; D010100:Oxygen / Q000494:pharmacology; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D022603:Shiga Toxins / Q000235:genetics* / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D011956:Receptors, Cell Surface; D022603:Shiga Toxins; C109287:Tir protein, E coli; C073819:eaeA protein, E coli; D010100:Oxygen