Primary Human Colon Epithelial Cells (pHCoEpiCs) Do Express the Shiga Toxin (Stx) Receptor Glycosphingolipids Gb3Cer and Gb4Cer and Are Largely Refractory but Not Resistant towards Stx

Int J Mol Sci. 2021 Sep 16;22(18):10002. doi: 10.3390/ijms221810002.

Abstract

Shiga toxin (Stx) is released by enterohemorrhagic Escherichia coli (EHEC) into the human intestinal lumen and transferred across the colon epithelium to the circulation. Stx-mediated damage of human kidney and brain endothelial cells and renal epithelial cells is a renowned feature, while the sensitivity of the human colon epithelium towards Stx and the decoration with the Stx receptor glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer, Galα1-4Galβ1-4Glcβ1-1Cer) and globotetraosylceramide (Gb4Cer, GalNAcβ1-3Galα1-4Galβ1-4Glcβ1-1Cer) is a matter of debate. Structural analysis of the globo-series GSLs of serum-free cultivated primary human colon epithelial cells (pHCoEpiCs) revealed Gb4Cer as the major neutral GSL with Cer (d18:1, C16:0), Cer (d18:1, C22:1/C22:0) and Cer (d18:1, C24:2/C24:1) accompanied by minor Gb3Cer with Cer (d18:1, C16:0) and Cer (d18:1, C24:1) as the dominant lipoforms. Gb3Cer and Gb4Cer co-distributed with cholesterol and sphingomyelin to detergent-resistant membranes (DRMs) used as microdomain analogs. Exposure to increasing Stx concentrations indicated only a slight cell-damaging effect at the highest toxin concentration of 1 µg/mL for Stx1a and Stx2a, whereas a significant effect was detected for Stx2e. Considerable Stx refractiveness of pHCoEpiCs that correlated with the rather low cellular content of the high-affinity Stx-receptor Gb3Cer renders the human colon epithelium questionable as a major target of Stx1a and Stx2a.

Keywords: Gb3Cer; Gb4Cer; Stx1a; Stx2a; Stx2e; colon epithelial cells; glycosphingolipids.

MeSH terms

  • Cell Line
  • Cells, Cultured
  • Chromatography, Thin Layer
  • Colon / metabolism*
  • Epithelial Cells / cytology*
  • Epithelial Cells / metabolism*
  • Globosides / metabolism*
  • Glycosphingolipids / metabolism
  • Humans
  • Mass Spectrometry
  • Shiga Toxin / metabolism*
  • Syntaxin 1 / metabolism
  • Trihexosylceramides / metabolism*

Substances

  • Globosides
  • Glycosphingolipids
  • STX1A protein, human
  • Syntaxin 1
  • Trihexosylceramides
  • globotetraosylceramide
  • globotriaosylceramide
  • Shiga Toxin