| Résumé | This chapter focuses on the chemical structure, biosynthesis, and potential pathogenic role of the lipopolysaccharides (LPSs) from Helicobacter pylori. The structures of LPSs isolated from Helicobacter species found in nonhuman primates, which give rise to similar gastric symptoms in their respective hosts, are also described. LPSs are glycolipid structures carried by bacteria on their cell surfaces, which are actively involved in biochemical interactions between the bacterium and its host. The detection of LPSs in H. pylori expressing structures homologous to human histo-blood-group antigens stands as one of the most important and crucial discoveries in both H. pylori and bacterial-LPS research. The production of Lewis determinants, blood-group A, and linear blood-group B by H. pylori, occasionally by a single strain, is a perfect example of molecular mimicry, and of the capability that bacteria possess to elaborate glycan structures similar to those present in their biological niche. In this case, H. pylori carry LPSs with structures similar to cell surface glycolipids and glycoconjugates expressed by the human gastric mucosa. The chapter presents several reasons why H. pylori produce histo-blood-group antigens. One of the reasons is based on the molecular mimicry premise, in that H. pylori produces host-like gastric-glycan structures in order to mimic its immediate surrounding and thus avoid being detected by the host's immune system, leading to an uninterrupted long life. |
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