In vitro binding of Helicobacter pylori to monohexosylceramides

H. pylori is the major cause of human gastritis, duodenal ulcer and thus ga stric adenocarcinoma. Many glycosphingolipid species have been postulated a s receptors for H. pylori and it is likely that H. pylori attachment requir es 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 chr omatograms was characterized under microaerobic conditions. All H. pylori c linical isolates, laboratory strains and type culture collection strains re cognized galactosylceramide (Gal beta 1Cer) with ceramide containing sphing osine 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 showe d the opposite binding preference. A clear preference in binding to Gal bet a 1Cer (type I) incorporated into liposome was shown by most tested strains . Clinical isolates bound well to glucosylceramide (Glc beta 1Cer) with hyd roxylated 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 so me 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 modu lation of the potential receptor function of monohexosylceramides and the d istinction between the receptor repertoire of H. pylori clinical isolates a nd cultured strains commonly used to study host-cell adhesion.