Inhibition of gastric mucosal laminin receptor by Helicobacter pylori lipopolysaccharide: effect of sucralfate.

Abstract

The maintenance of gastric mucosal integrity depends upon the interaction involving specific cell surface receptors with distinct proteins of extracellular matrix, one of which is laminin. We present here evidence that lipopolysaccharide from Helicobacter pylori interferes with laminin binding on the receptor. The laminin receptor was isolated from gastric epithelial cell membrane by the procedure involving membrane solubilization with octylglucoside followed by affinity chromatography on laminin-coupled Sepharose. The receptor protein yielded on SDS-PAGE a single 67 kDa band. After radioiodination, the protein was incorporated into liposomes which displayed specific affinity toward laminin-coated surface. The binding of liposomal receptor to the laminin-coated surface was inhibited by lipopolysaccharide from H. pylori. The inhibitory effect was proportional to the concentration of lipopolysaccharide up to 50 micrograms/ml, at which a 96% decrease in binding occurred. Introduction of sucralfate to the assay system led to the prevention of the inhibitory effect of lipopolysaccharide on the receptor-laminin binding. The effect was dose dependent and, at sucralfate concentration of 45 micrograms/ml, nearly complete restoration in binding was achieved. The results suggest that H. pylori also may be capable of disrupting the gastric mucosal integrity through a similar mechanism in vivo, and that anti-ulcer drug sucralfate counteracts this effect.