In vivo and in vitro studies of cytosolic phospholipase A2 expression in Helicobacter pylori infection

Modifications of mucosal phospholipids have been detected in samples from patients withHelicobacter pylori-positive gastritis. These alterations appear secondary to increased phospholipase A2activity (PLA2). The cytosolic form of this enzyme (cPLA2), normally involved in cellular signaling and growth, has been implicated in cancer pathogenesis. The aim of this study was to investigate cPLA2expression and PLA2activity in the gastric mucosae of patients with and withoutH. pyloriinfection. In gastric biopsies from 10H. pylori-positive patients, cPLA2levels, levels of mRNA as determined by reverse transcriptase PCR, levels of protein as determined by immunohistochemistry, and total PLA2activity were higher than in 10H. pylori-negative gastritis patients. To clarify whetherH. pylorihad a direct effect on the cellular expression of cPLA2, we studied cPLA2expression 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 differentH. pyloristrains. The levels of cPLA2, mRNA, and protein expression were unchanged in Hep-2 cells independently of cellular adhesion or invasion of the bacteria. Moreover, no change in cPLA2protein expression was observed in AGS or MKN 28 cells treated with wild-typeH. pylori. In conclusion, our study shows increased cPLA2expression and PLA2activity in the gastric mucosae of patients withH. pyloriinfection and no change in epithelial cell lines exposed toH. pylori.