title: Shiga toxin production and translocation during microaerobic human colonic infection with Shiga toxin-producing E. coli O157:H7 and O104:H4.
abstract: Haemolytic uraemic syndrome caused by Shiga toxin-producing E. coli (STEC) is dependent on release of Shiga toxins (Stxs) during intestinal infection and subsequent absorption into the bloodstream. An understanding of Stx-related events in the human gut is limited due to lack of suitable experimental models. In this study, we have used a vertical diffusion chamber system with polarized human colon carcinoma cells to simulate the microaerobic (MA) environment in the human intestine and investigate its influence on Stx release and translocation during STEC O157:H7 and O104:H4 infection. Stx2 was the major toxin type released during infection. Whereas microaerobiosis significantly reduced bacterial growth as well as Stx production and release into the medium, Stx translocation across the epithelial monolayer was enhanced under MA versus aerobic conditions. Increased Stx transport was dependent on STEC infection and occurred via a transcellular pathway other than macropinocytosis. While MA conditions had a similar general effect on Stx release and absorption during infection with STEC O157:H7 and O104:H4, both serotypes showed considerable differences in colonization, Stx production, and Stx translocation which suggest alternative virulence strategies. Taken together, our study suggests that the MA environment in the human colon may modulate Stx-related events and enhance Stx absorption during STEC infection.
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, UK; Gut Health and Food Safety Programme, Institute of Food Research, Norwich Research Park, Norwich, UK.
authors.forename: Seav-Ly
authors.initials: SL
authors.lastname: Tran
authors.forename: Lucile
authors.initials: L
authors.lastname: Billoud
authors.forename: Steven B
authors.initials: SB
authors.lastname: Lewis
authors.forename: Alan D
authors.initials: AD
authors.lastname: Phillips
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schüller
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D003108:Colonic Diseases / Q000382:microbiology / Q000473:pathology*; D015638:Cytochalasin D / Q000494:pharmacology; D004927:Escherichia coli Infections / Q000382:microbiology / Q000473:pathology*; D041981:Gastrointestinal Tract / Q000382:microbiology / Q000473:pathology; D006463:Hemolytic-Uremic Syndrome / Q000382:microbiology / Q000473:pathology; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D006801:Humans; D010100:Oxygen; D010873:Pinocytosis / Q000187:drug effects; D022621:Shiga Toxin / Q000096:biosynthesis / Q000378:metabolism*; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification / Q000472:pathogenicity*; D014709:Vero Cells
chemical_list: D006576:Heterocyclic Compounds, 4 or More Rings; C472645:blebbistatin; D015638:Cytochalasin D; D022621:Shiga Toxin; D010100:Oxygen