Inhibition of gastric mucosal laminin receptor by Helicobacter pylori lipopolysaccharide

Production of a conserved adhesin by the human gastroduodenal pathogen Helicobacter pylori

“…Immunochemical analysis with the antibodies which were eventually raised to the 19.6-kDa adhesin suggests that the protein is specific to and antigenically conserved in the species H. pylori and is not shared with H. mustelae, which displays adhesion characteristics similar 'to those of H. pyloni and in which adhesion appears to play a role in colonization and pathogenesis, or other Helicobacter species which appear not to attach to gastric mucosa (32 (41), and this binding capability should assume major importance once any initial microlesion in the ulceration process exposes the basement membrane. This exposure may result from H. pylon activity (37) or from something as simple as the loss of epithelial cells from the gastric surface which occurs during feeding. This sometimes exposes the lamina propria (46).…”

Increased in-vitro and in-vivo biological activity of lipopolysaccharide extracted from clinical low virulence vacA genotype Helicobacter pylori strains

“…These results indicate that new approaches are needed to understand the organic responses against H. pylori infection in man, and that strains with low virulence vacA alleles should not be disregarded and should be analysed for other attributes of virulence, such as biological activity of LPS, as it is known that this macromolecule is involved in events that induce epithelial disorganisation and mimicry in gastric epithelium [13,14].…”

“…On the other hand, both strains were cagA negative and had low virulence vacA genotypes (middle region m2), which have been associated with production of vacuolating cytotoxin of poor vacuolating activity and low levels of interleukin (IL)-8 secretion in in-vitro assays [30]. The increased response against these LPS preparations that were observed in mice might be a consequence of the experimental quality of the lipid A and the better affinity of the endotoxin with the immunocompetent cells, resembling the behaviour of the gastric epithelium in vivo where free LPS interacts with epithelial cells [31], allowing the lipid A to reach the membrane and induce the release of proinflammatory cytokines such as TNF-AE, IL-1 and IL-6 [13,32,33]. It is known that these related activities regulate secretion of other cytokines in the gastric mucosa [5,27].…”

“…Moreover, the role of LPS in ulcero-peptic disease has been questioned [12]. However, the increased evidence of the participation of LPS as an important virulence factor for gram-negative bacteria during infection, and the knowledge accumulated on their biological effects both in vitro and in vivo, suggest that this macromolecule might play a role in the inflammatory response and gastric epithelial damage observed in vivo during H. pylori infection [13,14].…”

Helicobacter pylori Interactions with Host Serum and Extracellular Matrix Proteins: Potential Role in the Infectious Process

“…The authors postulated that the initial recognition and binding of laminin by H. pylori could occur through LPS and that subsequently a more specific interaction involving a lectin-like protein present on the bacterial cell surface could take place. Slomiany et al (90) demonstrated that H. pylori cells, in particular H. pylori LPS, inhibited the interaction between a laminin receptor in gastric epithelial cells and laminin. They isolated from rat gastric epithelial cell membranes a protein of 67 kDa that was shown to bind laminin.…”