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Enterohemorrhagic Escherichia coli and a Fresh View on Shiga Toxin-Binding Glycosphingolipids of Primary Human Kidney and Colon Epithelial Cells and Their Toxin Susceptibility. Int J Mol Sci 2022; 23:ijms23136884. [PMID: 35805890 PMCID: PMC9266556 DOI: 10.3390/ijms23136884] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/07/2022] [Accepted: 06/17/2022] [Indexed: 02/06/2023] Open
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.
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Detzner J, Püttmann C, Pohlentz G, Humpf HU, Mellmann A, Karch H, Müthing J. 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; 22:ijms221810002. [PMID: 34576167 PMCID: PMC8472147 DOI: 10.3390/ijms221810002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 01/13/2023] Open
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.
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Affiliation(s)
- Johanna Detzner
- Institute for Hygiene, University of Münster, 48149 Münster, Germany; (J.D.); (C.P.); (G.P.); (A.M.); (H.K.)
| | - Charlotte Püttmann
- Institute for Hygiene, University of Münster, 48149 Münster, Germany; (J.D.); (C.P.); (G.P.); (A.M.); (H.K.)
| | - Gottfried Pohlentz
- Institute for Hygiene, University of Münster, 48149 Münster, Germany; (J.D.); (C.P.); (G.P.); (A.M.); (H.K.)
| | - Hans-Ulrich Humpf
- Institute for Food Chemistry, University of Münster, 48149 Münster, Germany;
| | - Alexander Mellmann
- Institute for Hygiene, University of Münster, 48149 Münster, Germany; (J.D.); (C.P.); (G.P.); (A.M.); (H.K.)
| | - Helge Karch
- Institute for Hygiene, University of Münster, 48149 Münster, Germany; (J.D.); (C.P.); (G.P.); (A.M.); (H.K.)
| | - Johannes Müthing
- Institute for Hygiene, University of Münster, 48149 Münster, Germany; (J.D.); (C.P.); (G.P.); (A.M.); (H.K.)
- Correspondence: ; Tel.: +49-(0)251-8355192
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Detzner J, Klein AL, Pohlentz G, Krojnewski E, Humpf HU, Mellmann A, Karch H, Müthing J. Primary Human Renal Proximal Tubular Epithelial Cells (pHRPTEpiCs): Shiga Toxin (Stx) Glycosphingolipid Receptors, Stx Susceptibility, and Interaction with Membrane Microdomains. Toxins (Basel) 2021; 13:toxins13080529. [PMID: 34437399 PMCID: PMC8402424 DOI: 10.3390/toxins13080529] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 12/13/2022] Open
Abstract
Tubular epithelial cells of the human kidney are considered as targets of Shiga toxins (Stxs) in the Stx-mediated pathogenesis of hemolytic–uremic syndrome (HUS) caused by Stx-releasing enterohemorrhagic Escherichia coli (EHEC). Analysis of Stx-binding glycosphingolipids (GSLs) of primary human renal proximal tubular epithelial cells (pHRPTEpiCs) yielded globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer) with Cer (d18:1, C16:0), Cer (d18:1, C22:0), and Cer (d18:1, C24:1/C24:0) as the dominant lipoforms. Investigation of detergent-resistant membranes (DRMs) and nonDRMs, serving as equivalents for the liquid-ordered and liquid-disordered membrane phase, respectively, revealed the prevalence of Gb3Cer and Gb4Cer together with cholesterol and sphingomyelin in DRMs, suggesting lipid raft association. Stx1a and Stx2a exerted strong cellular damage with half-maximal cytotoxic doses (CD50) of 1.31 × 102 pg/mL and 1.66 × 103 pg/mL, respectively, indicating one order of magnitude higher cellular cytotoxicity of Stx1a. Surface acoustic wave (SAW) real-time interaction analysis using biosensor surfaces coated with DRM or nonDRM fractions gave stronger binding capability of Stx1a versus Stx2a that correlated with the lower cytotoxicity of Stx2a. Our study underlines the substantial role of proximal tubular epithelial cells of the human kidney being associated with the development of Stx-mediated HUS at least for Stx1a, while the impact of Stx2a remains somewhat ambiguous.
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Affiliation(s)
- Johanna Detzner
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (A.-L.K.); (G.P.); (E.K.); (A.M.); (H.K.)
| | - Anna-Lena Klein
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (A.-L.K.); (G.P.); (E.K.); (A.M.); (H.K.)
| | - Gottfried Pohlentz
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (A.-L.K.); (G.P.); (E.K.); (A.M.); (H.K.)
| | - Elisabeth Krojnewski
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (A.-L.K.); (G.P.); (E.K.); (A.M.); (H.K.)
| | - Hans-Ulrich Humpf
- Institute of Food Chemistry, University of Münster, D-48149 Münster, Germany;
| | - Alexander Mellmann
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (A.-L.K.); (G.P.); (E.K.); (A.M.); (H.K.)
| | - Helge Karch
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (A.-L.K.); (G.P.); (E.K.); (A.M.); (H.K.)
| | - Johannes Müthing
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (A.-L.K.); (G.P.); (E.K.); (A.M.); (H.K.)
- Correspondence:
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Detzner J, Krojnewski E, Pohlentz G, Steil D, Humpf HU, Mellmann A, Karch H, Müthing J. Shiga Toxin (Stx)-Binding Glycosphingolipids of Primary Human Renal Cortical Epithelial Cells (pHRCEpiCs) and Stx-Mediated Cytotoxicity. Toxins (Basel) 2021; 13:toxins13020139. [PMID: 33673393 PMCID: PMC7918848 DOI: 10.3390/toxins13020139] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 12/12/2022] Open
Abstract
Human kidney epithelial cells are supposed to be directly involved in the pathogenesis of the hemolytic–uremic syndrome (HUS) caused by Shiga toxin (Stx)-producing enterohemorrhagic Escherichia coli (EHEC). The characterization of the major and minor Stx-binding glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer), respectively, of primary human renal cortical epithelial cells (pHRCEpiCs) revealed GSLs with Cer (d18:1, C16:0), Cer (d18:1, C22:0), and Cer (d18:1, C24:1/C24:0) as the dominant lipoforms. Using detergent-resistant membranes (DRMs) and non-DRMs, Gb3Cer and Gb4Cer prevailed in the DRM fractions, suggesting their association with microdomains in the liquid-ordered membrane phase. A preference of Gb3Cer and Gb4Cer endowed with C24:0 fatty acid accompanied by minor monounsaturated C24:1-harboring counterparts was observed in DRMs, whereas the C24:1 fatty acid increased in relation to the saturated equivalents in non-DRMs. A shift of the dominant phospholipid phosphatidylcholine with saturated fatty acids in the DRM to unsaturated species in the non-DRM fractions correlated with the GSL distribution. Cytotoxicity assays gave a moderate susceptibility of pHRCEpiCs to the Stx1a and Stx2a subtypes when compared to highly sensitive Vero-B4 cells. The results indicate that presence of Stx-binding GSLs per se and preferred occurrence in microdomains do not necessarily lead to a high cellular susceptibility towards Stx.
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Affiliation(s)
- Johanna Detzner
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (E.K.); (G.P.); (D.S.); (A.M.); (H.K.)
| | - Elisabeth Krojnewski
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (E.K.); (G.P.); (D.S.); (A.M.); (H.K.)
| | - Gottfried Pohlentz
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (E.K.); (G.P.); (D.S.); (A.M.); (H.K.)
| | - Daniel Steil
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (E.K.); (G.P.); (D.S.); (A.M.); (H.K.)
| | - Hans-Ulrich Humpf
- Institute of Food Chemistry, University of Münster, D-48149 Münster, Germany;
| | - Alexander Mellmann
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (E.K.); (G.P.); (D.S.); (A.M.); (H.K.)
| | - Helge Karch
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (E.K.); (G.P.); (D.S.); (A.M.); (H.K.)
| | - Johannes Müthing
- Institute of Hygiene, University of Münster, D-48149 Münster, Germany; (J.D.); (E.K.); (G.P.); (D.S.); (A.M.); (H.K.)
- Correspondence:
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Detzner J, Pohlentz G, Müthing J. Thin-Layer Chromatography in Structure and Recognition Studies of Shiga Toxin Glycosphingolipid Receptors. Methods Mol Biol 2021; 2291:229-252. [PMID: 33704756 DOI: 10.1007/978-1-0716-1339-9_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Glycosphingolipids (GSLs) consist of a ceramide (Cer) lipid anchor, which is typically composed of the long-chain aminoalcohol sphingosine (d18:1) and a fatty acid (mostly C16-C24) and a sugar moiety harboring to a great extent one to five monosaccharides. GSLs of the globo-series are well-recognized receptors of Shiga toxins (Stxs) released by Stx-producing Escherichia coli (STEC). Receptors for the Stx subtypes Stx1a and Stx2a are globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer), whereby Gb3Cer represents their high-affinity and Gb4Cer their low-affinity receptor. In addition to Gb3Cer and Gb4Cer, Gb5Cer and Forssman GSL are further receptors of the Stx2e subtype rendering Stx2e unique among the various Stx subtypes. Thin-layer chromatography (TLC) is a convenient and ubiquitously employed method for analyzing GSL mixtures of unknown composition. In particular, TLC immunochemical overlay detection allows for sensitive identification of Stx-binding GSLs in complex mixtures directly on the TLC plate. For this purpose, specific anti-GSL antibodies or Stxs themselves in conjunction with anti-Stx antibodies can be used. The described protocols of antibody-mediated detection of TLC-separated globo-series GSLs and corresponding identification of Stx-binding globo-series GSLs will provide detailed advice for successful GSL analysis and particularly highlight the power of the TLC overlay technique.
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Affiliation(s)
- Johanna Detzner
- Institute for Hygiene, University of Münster, Münster, Germany
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Valid Presumption of Shiga Toxin-Mediated Damage of Developing Erythrocytes in EHEC-Associated Hemolytic Uremic Syndrome. Toxins (Basel) 2020; 12:toxins12060373. [PMID: 32512916 PMCID: PMC7354503 DOI: 10.3390/toxins12060373] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 02/06/2023] Open
Abstract
The global emergence of clinical diseases caused by enterohemorrhagic Escherichia coli (EHEC) is an issue of great concern. EHEC release Shiga toxins (Stxs) as their key virulence factors, and investigations on the cell-damaging mechanisms toward target cells are inevitable for the development of novel mitigation strategies. Stx-mediated hemolytic uremic syndrome (HUS), characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury, is the most severe outcome of an EHEC infection. Hemolytic anemia during HUS is defined as the loss of erythrocytes by mechanical disruption when passing through narrowed microvessels. The formation of thrombi in the microvasculature is considered an indirect effect of Stx-mediated injury mainly of the renal microvascular endothelial cells, resulting in obstructions of vessels. In this review, we summarize and discuss recent data providing evidence that HUS-associated hemolytic anemia may arise not only from intravascular rupture of erythrocytes, but also from the extravascular impairment of erythropoiesis, the development of red blood cells in the bone marrow, via direct Stx-mediated damage of maturing erythrocytes, leading to “non-hemolytic” anemia.
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Kehl A, Kuhn R, Detzner J, Steil D, Müthing J, Karch H, Mellmann A. Modeling Native EHEC Outer Membrane Vesicles by Creating Synthetic Surrogates. Microorganisms 2020; 8:microorganisms8050673. [PMID: 32384757 PMCID: PMC7284840 DOI: 10.3390/microorganisms8050673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/28/2020] [Accepted: 04/30/2020] [Indexed: 12/28/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is a zoonotic pathogen responsible for life-threating diseases such as hemolytic uremic syndrome. While its major virulence factor, the Shiga toxin (Stx), is known to exert its cytotoxic effect on various endothelial and epithelial cells when in its free, soluble form, Stx was also recently found to be associated with EHEC outer membrane vesicles (OMVs). However, depending on the strain background, other toxins can also be associated with native OMVs (nOMVs), and nOMVs are also made up of immunomodulatory agents such as lipopolysaccharides and flagellin. Thus, it is difficult to determine to which extent a single virulence factor in nOMVs, such as Stx, contributes to the molecular pathogenesis of EHEC. To reduce this complexity, we successfully developed a protocol for the preparation of synthetic OMVs (sOMVs) with a defined lipid composition resembling the E. coli outer membrane and loaded with specific proteins, i.e., bovine serum albumin (BSA) as a proxy for functional Stx2a. Using BSA for parameter evaluation, we found that (1) functional sOMVs can be prepared at room temperature instead of potentially detrimental higher temperatures (e.g., 45 °C), (2) a 1:10 ratio of protein to lipid, i.e., 100 µg protein with 1 mg of lipid mixture, yields homogenously sized sOMVs, and (3) long-term storage for up to one year at 4 °C is possible without losing structural integrity. Accordingly, we reproducibly generated Stx2a-loaded sOMVs with an average diameter of 132.4 ± 9.6 nm that preserve Stx2a’s injuring activity, as determined by cytotoxicity assays with Vero cells. Overall, we successfully created sOMVs and loaded them with an EHEC toxin, which opens the door for future studies on the degree of virulence associated with individual toxins from EHEC and other bacterial pathogens.
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Affiliation(s)
- Alexander Kehl
- Institute of Hygiene, University of Münster, 48149 Münster, Germany; (R.K.); (J.D.); (D.S.); (J.M.); (H.K.)
- Correspondence: (A.K.); (A.M.); Tel.: +49-(0)251-83-55233 (A.K.); +49-(0)251-83-55361 (A.M.)
| | - Ronja Kuhn
- Institute of Hygiene, University of Münster, 48149 Münster, Germany; (R.K.); (J.D.); (D.S.); (J.M.); (H.K.)
| | - Johanna Detzner
- Institute of Hygiene, University of Münster, 48149 Münster, Germany; (R.K.); (J.D.); (D.S.); (J.M.); (H.K.)
| | - Daniel Steil
- Institute of Hygiene, University of Münster, 48149 Münster, Germany; (R.K.); (J.D.); (D.S.); (J.M.); (H.K.)
| | - Johannes Müthing
- Institute of Hygiene, University of Münster, 48149 Münster, Germany; (R.K.); (J.D.); (D.S.); (J.M.); (H.K.)
| | - Helge Karch
- Institute of Hygiene, University of Münster, 48149 Münster, Germany; (R.K.); (J.D.); (D.S.); (J.M.); (H.K.)
- National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University of Münster, 48149 Münster, Germany
| | - Alexander Mellmann
- Institute of Hygiene, University of Münster, 48149 Münster, Germany; (R.K.); (J.D.); (D.S.); (J.M.); (H.K.)
- National Consulting Laboratory for Hemolytic Uremic Syndrome (HUS), University of Münster, 48149 Münster, Germany
- Correspondence: (A.K.); (A.M.); Tel.: +49-(0)251-83-55233 (A.K.); +49-(0)251-83-55361 (A.M.)
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