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

Modifications of mucosal phospholipids have been detected in samples from patients with Helicobacter pylori-positive gastritis. These alterations appear secondary to increased phospholipase A sub(2) activity (PLA sub(2)). The cytosolic form of this enzyme (cPLA sub(2)), normally involved in cellular signaling and growth, has been implicated in cancer pathogenesis. The aim of this study was to investigate cPLA sub(2) expression and PLA sub(2) activity in the gastric mucosae of patients with and without H. pylori infection. In gastric biopsies from 10 H. pylori- positive patients, cPLA sub(2) levels, levels of mRNA as determined by reverse transcriptase PCR, levels of protein as determined by immunohistochemistry, and total PLA sub(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 sub(2), we studied cPLA sub(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 sub(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 sub(2) protein expression was observed in AGS or MKN 28 cells treated with wild-type H. pylori. In conclusion, our study shows increased cPLA sub(2) expression and PLA sub(2) activity in the gastric mucosae of patients with H. pylori infection and no change in epithelial cell lines exposed to H. pylori.