Shiga toxin production and translocation during microaerobic human colonic infection withShiga toxin‐producingE. coli O157:H7andO104:H4

Abstract

SummaryHaemolytic 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.

Oxygen and contact with human intestinal epithelium independently stimulate virulence gene expression in enteroaggregativeEscherichia coli

“…In our previous studies, we have shown that T84 cells grown on Snapwell supports form polarised and well‐differentiated epithelial monolayers that can be maintained in the MA VDC for at least 6 hr without loss of barrier function or cell viability (Schüller & Phillips, ; Tran, Billoud, Lewis, Phillips, & Schüller, ). To optimise the system for EAEC infection, we first determined the growth kinetics of strains 17‐2 and 042 under aerobic (AE) and MA conditions and simultaneously quantified the concentrations of dissolved oxygen in the media.…”

Enterotoxigenic and Enterohemorrhagic <i>Escherichia coli</i>: Survival and Modulation of Virulence in the Human Gastrointestinal Tract

“…In other recent studies, polarized human colon carcinoma cells in a vertical diffusion chamber system were used to investigate the influence of reduced apical oxygen levels on EHEC colonization [38] and Stx production [71]. The authors demonstrated that both EHEC-host adhesion and expression and translocation of T3SS effector proteins were increased under microaerobic conditions (1-2% oxygen).…”

Pathogenomes of Atypical Non-shigatoxigenic Escherichia coli NSF/SF O157:H7/NM: Comprehensive Phylogenomic Analysis Using Closed Genomes

“…The 70-kDa toxin acts as a protein synthesis inhibitor (Melton-Celsa, 2014), causing cytopathic effects in renal endothelial cells (Konowalchuk et al, 1977;Sandvig, 2001;Tesh, 2010;Bentancor et al, 2013a,b;Lee et al, 2016). Stx is especially toxigenic to renal cells, which express the Stx-receptor globotriaosylceramide or Gb3 (Eaton et al, 2008;Shin et al, 2009;Johannes and Romer, 2010;Mauro and Koudelka, 2011;Melton-Celsa et al, 2012;Nguyen and Sperandio, 2012;Tran et al, 2014;Pacheco et al, 2018). Stx-phages are comprised of highly diverse entities (Miyamoto et al, 1999;Muniesa et al, 2004;Gamage et al, 2006;Smith et al, 2012;Kruger and Lucchesi, 2015;Shaaban et al, 2016) and their genome plasticity has been implicated to directly, or indirectly, alter Stx production (Miyamoto et al, 1999;Wagner et al, 1999;Muniesa et al, 2003;Tyler et al, 2004;Ogura et al, 2015;Yin et al, 2015).…”