In Vivo and In Vitro Studies of Cytosolic Phospholipase A 2 Expression in Helicobacter pylori Infection

Abstract

ABSTRACT Modifications of mucosal phospholipids have been detected in samples from patients with Helicobacter pylori -positive gastritis. These alterations appear secondary to increased phospholipase A 2 activity (PLA 2 ). The cytosolic form of this enzyme (cPLA 2 ), normally involved in cellular signaling and growth, has been implicated in cancer pathogenesis. The aim of this study was to investigate cPLA 2 expression and PLA 2 activity in the gastric mucosae of patients with and without H. pylori infection. In gastric biopsies from 10 H. pylori -positive patients, cPLA 2 levels, levels of mRNA as determined by reverse transcriptase PCR, levels of protein as determined by immunohistochemistry, and total PLA 2 activity were higher than in 10 H. pylori -negative gastritis patients. To clarify whether H. pylori had a direct effect on the cellular expression of cPLA 2 , we studied cPLA 2 expression in vitro with different human epithelial cell lines, one from a patient with larynx carcinoma (i.e., HEp-2 cells) and two from patients with gastric adenocarcinoma (i.e., AGS and MKN 28 cells), incubated with different H. pylori strains. The levels of cPLA 2 , mRNA, and protein expression were unchanged in Hep-2 cells independently of cellular adhesion or invasion of the bacteria. Moreover, no change in cPLA 2 protein expression was observed in AGS or MKN 28 cells treated with wild-type H. pylori . In conclusion, our study shows increased cPLA 2 expression and PLA 2 activity in the gastric mucosae of patients with H. pylori infection and no change in epithelial cell lines exposed to H. pylori .