Why Helicobacter pylori has Lewis antigens

Institute for Biological Sciences, NRC, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6
Trends in Microbiology (Impact Factor: 9.81). 01/2001; DOI: 10.1016/S0966-842X(00)01875-8

ABSTRACT In mimicry with human gastric epithelial cells, the lipopolysaccharide of Helicobacter pylori expresses Lewis blood group antigens. Recent data suggest that molecular mimicry does not promote immune evasion, nor does it lead to induction of autoantibodies, but that H. pylori Lewis X mediates adhesion to gastric epithelial cells and is essential for colonization.

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    ABSTRACT: To assess the influence of monoclonal anti-Lewis b, anti-H type 1, and anti-sialyl Lewis x addition on interactions of sugar structures of MUC1 mucin with Helicobacter pylori. The investigations were carried out on gastric juices of 11 patients and 12 H. pylori strains. The levels of Lewis b and sialyl Lewis x antigens on MUC1 were assessed by sandwich ELISA tests. Anti-Lewis b, anti-H type 1 or anti-sialyl Lewis x monoclonal antibodies were added to MUC1 to determine whether the adhesion activities of H. pylori isolates to examined mucin would be affected. Binding of bacteria to MUC1 was assessed by ELISA test. Clear inhibitory effect of examined antibodies was revealed in 6 of 12 examined H. pylori isolates independently on babA2 status. In the rest of strains this effect was negligible. We confirmed participation of Lewis b, H type 1 and also sialyl Lewis x of MUC1 mucin in interactions with H. pylori independently on babA genopositivity. Not full inhibition and a lack of this effect in some strains suggest an existence of other mechanisms of H. pylori adherence to mucin.
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    ABSTRACT: Helicobacter pylori is an adapted gastric pathogen that colonizes the human stomach, causing severe gastritis and gastric cancer. A hallmark of infection is the ability of this organism to evade detection by the human immune system. H. pylori has evolved a number of features to achieve this, many of which involve glyco-conjugates including the lipopolysaccharide, peptidoglycan layer, glycoproteins, and glucosylated cholesterol. These major bacterial components possess unique features from those of other gram-negative organisms, including differences in structure, assembly, and modification. These defining characteristics of H. pylori glycobiology help the pathogen establish a long-lived infection by providing camouflage, modulating the host immune response, and promoting virulence mechanisms. In this way, glyco-conjugates are essential for H. pylori pathogenicity and survival, allowing it to carve out a niche in the formidable environment of the human stomach.
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    ABSTRACT: Crohn's disease and ulcerative colitis are chronic dis- abling inflammatory bowel diseases (IBDs). Although the causes of IBD are unknown, defects in innate and adaptive immune pathways have been identified and biological therapies that target key molecules have been designed. Infliximab, a chimeric immunoglobulin (Ig)G1 monoclonal antibody to tumor necrosis factor, dramatically improved treatment of patients with Crohn's disease and ulcerative colitis. Infliximab has achieved treatment goals such as mucosal healing and decreasing the need for hospitalizations and surgeries. Although several anti-tumor necrosis factor therapies have been developed, there is a great need for drugs that target other pathways. Natalizumab, an antibody against the integrin 4 subunit, blocks leukocyte adhe- sion and has reached the clinic in the United States but has not been approved in the European Union; other anti-adhesion molecules currently are under develop- ment. Additional approaches under clinical develop- ment include therapeutics that target cytokines, such as interleukin-12/23, as well as those that block T-cell sig- naling. The use of recombinant human proteins, in- cluding immunoregulatory cytokines and growth fac- tors, has not been successful so far. The efficacy of each therapy must be shown in carefully designed clinical programs. Biological therapies carry a definite safety risk, so their place in treatment algorithms must be defined carefully.