In vitro binding of Helicobacter pylori to monohexosylceramides

H. pylori is the major cause of human gastritis, duodenal ulcer and thus gastric adenocarcinoma. Many glycosphingolipid species have been postulated as receptors for H. pylori and it is likely that H. pylori attachment requires multiple, perhaps sequential receptor/ligand interactions. In this study, the binding of a number of H. pylori clinical isolates, as well as stock strains, to acid and neutral glycosphingolipids separated on thin-layer chromatograms was characterized under microaerobic conditions. All H. pylori clinical isolates, laboratory strains and type culture collection strains recognized galactosylceramide (Gal beta 1Cer) with ceramide containing sphingosine and hydroxylated fatty acid (type I), or non-hydroxylated fatty acid (type II), on thin-layer chromatograms and when incorporated into liposomes. The clinical isolates bound stronger to Gal beta 1Cer (type II) than Gal beta 1Cer (type I) on TLC, whereas lab and culture collection strains showed the opposite binding preference. A clear preference in binding to Gal beta 1Cer (type I) incorporated into liposome was shown by most tested strains. Clinical isolates bound well to glucosylceramide (Glc beta 1Cer) with hydroxylated fatty acid, whereas weak binding to this glycolipid was detected with the lab and type collection strains. None of the tested strains bound Glc beta 1Cer with non-hydroxylated fatty acid on the solid surface, but some strains of both clinical or type collection origins showed weak or very weak binding in the liposome assay. A clear distinction between the binding specificity of living organisms (under microaerobic conditions) as opposed to dying organisms (under normoxic conditions) illustrates the importance of cellular physiology in this process. These studies illustrate lipid modulation of the potential receptor function of monohexosylceramides and the distinction between the receptor repertoire of H. pylori clinical isolates and cultured strains commonly used to study host-cell adhesion.