Haemolytic uraemic syndrome (HUS) is a complication which may arise upon enterohaemorrhagic E. coli (EHEC) colonisation of the colon. The development of HUS is associated to Shiga toxins (Stxs) release leading to organ damage. It has been found that Stx release can occur within outer membrane vesicles (OMVs). Hence, the effect of different intestinal environment cues on EHEC OMV production was examined. OMVs were purified following EHEC growth in Luria broth (LB), simulated colonic environmental medium (SCEM) with or without bile salts, and in the presence or absence of human cell lines. Yield was quantified through SDS-PAGE and densitometric analysis of outer membrane proteins F/C and A. Furthermore, OMV uptake by HEp-2 and T84 cells was analysed by incubating such cells with OMVs labelled fluorescent lipophilic dye and fluorescence microscopy. Different OMV yields were attained under different conditions, with human cell growth medium and SCEM producing significantly more than cultures grown in LB, with further increases in the presence of bile salts. The presence of HEp-2 cells did not affect OMV yield, yet a lower yield was attained in the presence of T84 cells. These results suggest that colonic environmental factors may influence EHEC OMV production in vivo. OMVs were also shown to be up-taken by both cell types. Such observations with T84 cells suggest that the human colonic epithelium can uptake OMVs. Coupled with Stx, this data may offer a paradigm on how OMVs contribute to Stx translocation across the gut barrier, subsequently leading to HUS.

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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