Abstract
The structural diversity of the lipopolysaccharides (LPSs) from Helicobacter pylori poses a challenge to establish accurate and strain-specific structure-function relationships in interactions with the host. Here, LPS structural domains from five clinical isolates were obtained and compared with the reference strain 26695. This was achieved combining information from structural analysis (GC-MS and ESI-MSn) with binding data after interrogation of a LPS-derived carbohydrate microarray with sequence-specific proteins. All LPSs expressed Lewisx/y and N-acetyllactosamine determinants. Ribans were also detected in LPSs from all clinical isolates, allowing their distinction from the 26695 LPS. There was evidence for 1,3-d-galactans and blood group H-type 2 sequences in two of the clinical isolates, the latter not yet described for H. pylori LPS. Furthermore, carbohydrate microarray analyses showed a strain-associated LPS recognition by the immune lectins DC-SIGN and galectin-3 and revealed distinctive LPS binding patterns by IgG antibodies in the serum from H. pylori-infected patients.
Highlights
Helicobacter pylori is a pathogenic Gram-negative bacterium that colonizes the human stomach of about 50 % of world’s population (Hooi et al, 2017)
Comparing the IgG reactivity of Hp+ and Hp- groups against other bacterial lipo polysaccharides (LPSs), likely due to the cross reactivity with other LPS antigens, no significant differences were observed (Fig. 5b). These results show that the IgG antibody responses detected with Hp+ sera are specific for structures present in the LPS of H. pylori clinical isolates that are highly immunogenic in humans (Pece et al, 1997)
The present study extends current knowledge on the chemical structures of H. pylori LPS by combining structural analysis and carbo hydrate microarray analyses with carbohydrate sequence-specific pro teins
Summary
Helicobacter pylori is a pathogenic Gram-negative bacterium that colonizes the human stomach of about 50 % of world’s population (Hooi et al, 2017). The adherence of bacteria to the gastric mucosa, which promotes initial attachment and persistence, is mediated by bacterial adhesins that target host glycans (Magalhaes & Reis, 2010). A unique feature of the O-chain of the LPSs of most H. pylori strains is the expression of Lewis (Le) antigens, mimicking those of gastric epithelium (Monteiro, 2001). This camouflage assists bacteria to escape from host’s immune responses and may induce autoimmune disorders, contributing to the severity and chronicity of infection (Moran & Prendergast, 2001)
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