Selective upregulation of endothelial E-selectin in response to Helicobacter pylori-induced gastritis

Helicobacter pylori is one of the most common bacterial pathogens, infecting up to 50% of the world's population. The host is not able to clear the infection, leading to life-long chronic inflammation with continuous infiltration of lymphocytes and granulocytes. The migration of leukocytes from the blood into inflamed tissue is dependent on adhesion molecules expressed on the vascular endothelium. The aim of this study was to characterize the effect of H. pylori-induced gastritis with regard to the expression of endothelial adhesion molecules in the gastric mucosa and compare this to other types of chronic mucosal inflammations. Our results demonstrate an increased level of expression of the adhesion molecule E-selectin, but not of intracellular adhesion molecule 1, vascular adhesion molecule 1, or vascular adhesion protein 1, in H. pylori-induced gastritis but not in gastritis induced by acetylsalicylic acid or pouchitis. The upregulated E-selectin expression was determined to be localized to the gastric mucosa rather than being a systemic response to the infection. Moreover, the H. pylori type IV secretion system encoded by the cag pathogenicity island (cagPAI) was found to be an important determinant for the upregulation of human endothelial E-selectin expression in vitro, and this process is probably dependent on the CagL protein, mediating binding to alpha5beta1 integrins. Thus, endothelial E-selectin expression induced by H. pylori probably contributes to the large influx of neutrophils and macrophages seen in infected individuals, and our results suggest that this process may be more pronounced in patients infected with cagPAI-positive H. pylori strains and may thereby contribute to tissue damage in these individuals.