Enterohemorrhagic Escherichia coli and a Fresh View on Shiga Toxin-Binding Glycosphingolipids of Primary Human Kidney and Colon Epithelial Cells and Their Toxin Susceptibility

Abstract

Enterohemorrhagic Escherichia coli (EHEC) are the human pathogenic subset of Shiga toxin (Stx)-producing E. coli (STEC). EHEC are responsible for severe colon infections associated with life-threatening extraintestinal complications such as the hemolytic-uremic syndrome (HUS) and neurological disturbances. Endothelial cells in various human organs are renowned targets of Stx, whereas the role of epithelial cells of colon and kidneys in the infection process has been and is still a matter of debate. This review shortly addresses the clinical impact of EHEC infections, novel aspects of vesicular package of Stx in the intestine and the blood stream as well as Stx-mediated extraintestinal complications and therapeutic options. Here follows a compilation of the Stx-binding glycosphingolipids (GSLs), globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) and their various lipoforms present in primary human kidney and colon epithelial cells and their distribution in lipid raft-analog membrane preparations. The last issues are the high and extremely low susceptibility of primary renal and colonic epithelial cells, respectively, suggesting a large resilience of the intestinal epithelium against the human-pathogenic Stx1a- and Stx2a-subtypes due to the low content of the high-affinity Stx-receptor Gb3Cer in colon epithelial cells. The review closes with a brief outlook on future challenges of Stx research.

Shiga Toxin (Stx) Type 1a and Stx2a Translocate through a Three-Layer Intestinal Model

“…In designing a cellular intestinal model to investigate Stx translocation, we selected three human-derived cell populations (i.e., colonic epithelia, myofibroblasts, and colonic microvascular endothelia) to represent three sections of tissue that play key roles in Stx translocation and tissue targeting (i.e., intestinal luminal lining, mesenchymal connective layer, vascular lining; see Figure 1 [ 4 , 5 , 25 ]). Prior to assembling the cells into multi-layer transwell cultures, our first steps were to ensure the cells could be co-cultured and could express appropriate genotypic and phenotypic markers in vitro.…”

“…The Stxs are composed of a single enzymatically active A subunit that is responsible for the cytotoxic activity and a non-covalently linked pentamer of B subunits that mediates receptor binding [ 4 ]. Stx1a and Stx2a use globotriaosylceramide (Gb3) as the preferred receptor to enter host cells [ 5 ]. Gb3 is present on endothelial cells in the kidney, central nervous system, and, in limited quantities, on human colonic epithelial cells [ 5 , 6 ].…”

“…Stx1a and Stx2a use globotriaosylceramide (Gb3) as the preferred receptor to enter host cells [ 5 ]. Gb3 is present on endothelial cells in the kidney, central nervous system, and, in limited quantities, on human colonic epithelial cells [ 5 , 6 ]. The Stxs also exhibit a limited capacity to bind alternate receptors such as globotetraosylceramide, Gb4 [ 7 ] and Toll-like receptor 4 (TLR4) [ 8 ].…”

Genomic island-encoded regulatory proteins in enterohemorrhagic Escherichia coli O157:H7

“…Stxs are divided into two groups, termed Stx1 and Stx2, which are 56% homologous at the amino acid level [ 81 ]. Stxs are potent cytotoxins that bind to host globotriaosylceramide (Gb3) or globotetraosylceramide (Gb4) receptors, leading to the inhibition of protein synthesis through the specific removal of a single adenine residue from the 28S rRNA of the 60S ribosomal subunit [ 80 , 82 ]. However, the detailed mechanisms of Stx transcription, translation and translocation to various tissues are not fully understood.…”

Scientific Discoveries Supporting Theories in Science: From Thinking to Practice

“…The article by Detzner, J. et al [ 26 ] is a review that discusses the clinical impact of infections by Enterohemorrhagic Escherichia coli (EHEC), a human pathogenic subset of Shiga toxin (Stx)-producing E. coli (STEC). It is an important issue inasmuch as Stx, together with localizing through a vesicular package in the intestine, travels through the body into the blood stream, in turn, being the major cause of Stx-mediated extraintestinal complications.…”