The Multiple Carbohydrate Binding Specificities of Helicobacter pylori

Helicobacter pylori-binding nonacid glycosphingolipids in the human stomach

Helicobacter pylori has a number of well-characterized carbohydrate-binding adhesins (BabA, SabA, and LabA) that promote adhesion to the gastric mucosa. In contrast, information on the glycoconjugates present in the human stomach remains unavailable. Here, we used MS and binding of carbohydrate-recognizing ligands to characterize the glycosphingolipids of three human stomachs from individuals with different blood group phenotypes (O(Rh-)P, A(Rh+)P, and A(Rh+)p), focusing on compounds recognized by H. pylori We observed a high degree of structural complexity, and the composition of glycosphingolipids differed among individuals with different blood groups. The type 2 chain was the dominating core chain of the complex glycosphingolipids in the human stomach, in contrast to the complex glycosphingolipids in the human small intestine, which have mainly a type 1 core. H. pylori did not bind to the O(Rh-)P stomach glycosphingolipids, whose major complex glycosphingolipids were neolactotetraosylceramide, the Le^x, Le^a, and H type 2 pentaosylceramides, and the Le^y hexaosylceramide. Several H. pylori-binding compounds were present among the A(Rh+)P and A(Rh+)p stomach glycosphingolipids. Ligands for BabA-mediated binding of H. pylori were the Le^b hexaosylceramide, the H type 1 pentaosylceramide, and the A type 1/ALe^b heptaosylceramide. Additional H. pylori-binding glycosphingolipids recognized by BabA-deficient strains were lactosylceramide, lactotetraosylceramide, the x₂ pentaosylceramide, and neolactohexaosylceramide. Our characterization of human gastric receptors required for H. pylori adhesion provides a basis for the development of specific compounds that inhibit the binding of this bacterium to the human gastric mucosa.

Anti-Helicobacter pylori effect of CaG-NANA, a new sialic acid derivative

AIM

To investigate the bactericidal effects of calcium chelated N-acetylneuraminic acid-glycomacropeptide (CaG-NANA) against Helicobacter pylori (H. pylori).

METHODS

For manufacture of CaG-NANA, calcium (Ca) was combined with glycomacropeptide (GMP) by chelating, and N-acetylneuraminic acid (NANA) was produced with Ca-GMP substrate by an enzymatic method. The final concentration of each component was 5% Ca, 7% NANA, 85% GMP, and 3% water. For in vitro study, various concentrations of CaG-NANA were investigated under the minimal inhibitory concentration (MIC). For in vivo study, CaG-NANA was administered orally for 3 wk after H. pylori infection. The levels of inflammatory cytokines in blood were analyzed by enzyme-linked immunosorbent assay and eradication of H. pylori was assessed by histological observation.

RESULTS

The time-kill curves showed a persistent decrease in cell numbers, which depended on the dose of CaG-NANA, and MIC of CaG-NANA against H. pylori was 0.5% in vitro. Histopathologic observation revealed no obvious inflammation or pathologic changes in the gastric mucosa in the CaG-NANA treatment group in vivo. The colonization of H. pylori was reduced after CaG-NANA treatment. The levels of interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and IL-10 were also decreased by CaG-NANA.

CONCLUSION

CaG-NANA demonstrates effective anti-bactericidal activity against H. pylori both in vitro and in vivo.