Helicobacter pylorigamma-glutamyltranspeptidase upregulates COX-2 and EGF-related peptide expression in human gastric cells

Abstract

Gastric mucosa responds to\ud Helicobacter pylori induced cell damage by increasing the expression of COX-2 and EGF-related peptides. We sought to investigate the bacterial virulence factor/s and the host\ud cellular pathways involved in the upregulation of\ud COX-2, HB-EGF and amphiregulin in MKN 28 and AGS\ud gastric mucosal cells.\ud H. pylori strain CCUG 17874 was grown in Brucella broth supplemented with 0.2% (2,6-dimethyl)-b-cyclodextrins. The soluble proteins released in the culture medium by the bacterium were fractionated by exclusion size and anion exchange\ud chromatography. A single peak retaining the ability to\ud upregulate COX-2 and HB-EGF mRNA and protein\ud expression was obtained. SDS-PAGE analysis of the\ud peak showed two peptides with an apparent molecular\ud weight of 38 and 22 kDa, which were identified\ud by automated Edman degradation analysis as the\ud N-terminal and C-terminal peptides of H. pylori\ud g-glutamyltranspeptidase respectively. Acivicin, a\ud selective g-glutamyltranspeptidase inhibitor, counteracted\ud H. pylori-induced upregulation of COX-2 and\ud EGF-related peptide mRNA expression. An\ud H. pylori isogenic mutant g-glutamyltranspeptidase-deficient\ud strain did not exert any effect on COX-2, HB-EGF and\ud amphiregulin mRNA expression. Blockade of phosphatidylinositol-\ud 3 kinase and p38 kinase, but not MAP kinase kinase, inhibited\ud H. pylori g-glutamyltranspeptidase-induced upregulation of COX-2 and EGFrelated peptide mRNA expression