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Interaction of Shiga toxin with primary human intestinal and renal epithelial cells: glycovesicles as novel toxin inhibitors

Subject Area Medical Microbiology and Mycology, Hygiene, Molecular Infection Biology
Term from 2018 to 2021
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 404813761
 
Final Report Year 2022

Final Report 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 are currently discussed intensively. The Stx-binding glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) and their various lipoforms have been scrutinized in this project for primary human kidney and colon epithelial cells. The mass spectra obtained by electrospray ionization mass spectrometry of Gb3Cer, Gb4Cer, and Gb5Cer of kidney epithelial cells revealed lipoforms carrying sphingosine (d18:1) in the ceramide lipid anchor linked with C16:0, C22:0, or C24:1/C24:0 fatty acyl chains.The dominant Gb3Cer and Gb4Cer lipoforms of colon epithelial cells harbor sphingosine (d18:1) linked to C16:0, C22:1/C22:0, or C24:1/C24:2 fatty acyl chains, whereas Gb3Cer and Gb4Cer lipoforms with C24:0 fatty acyl chains were missing. Collectively, renal epithelial cells exhibit a more complex profile with a higher extent of lipoform variability regarding the Stx receptors Gb3Cer and Gb4Cer and exhibit as a unique feature Gb5Cer, which is undetectable in colonic epithelial cells. The preferential distribution of Gb3Cer and Gb4Cer in lipid raft-analog membrane preparations indicated the association of the Stx receptor GSLs with membrane microdomains. The cytotoxic activity of swine-pathogenic Stx2e subtype towards porcine renal epithelial cells could be reduced using glycovesicles spiked with Gb3- and Gb4-neoglycolipids (neoGLs) carrying a phosphatidylethanolamine (PE) lipid anchor, and the Stx1a- and Stx2a-mediated cytotoxic action against Vero cells could be mitigated using pectin-derived neoGLs of (α1-4)Galn-PE type, which have been produced by us. Our results gave evidence for a large resilience of primary human colon epithelial cells against Stx1a and Stx2a most probably due to their low content of the high-affinity Stx-receptor Gb3Cer. On the other hand, kidney epithelial cells were highly sensitive towards Stx1a and Stx2a. This data suggest that kidney epithelial cells are putative targets in the onset of the life-threatening HUS and could be involved in the clinical picture of the disease, whereas colon epithelial cells can be excluded as major targets for Stx1a and Stx2a.

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