In vivo and in vitro studies of cytosolic phospholipase A(2) expression inHelicobacter pylori infection

Modifications of mucosal phospholipids have been detected in samples from p atients with Helicobacter pylori-positive gastritis. These alterations appe ar secondary to increased phospholipase A(2) activity (PLA(2)). The cytosol ic form of this enzyme (cPLA(2)), normally involved in cellular signaling a nd growth, has been implicated in cancer pathogenesis. The aim of this stud y was to investigate cPLA(2) expression and PLA(2) activity in the gastric mucosae of patients with and without H. pylori infection. In gastric biopsi es from 10 H. pylori-positive patients, cPLA(2) levels, levels of mRNA as d etermined by reverse transcriptase PCR, levels of protein as determined by immunohistochemistry, and total PLA(2) activity were higher than in 10 H. p ylori-negative gastritis patients. To clarify whether H. pylori had a direc t effect on the cellular expression of cPLA(2), we studied cPLA(2) expressi on 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 gastri c adenocarcinoma (i.e., AGS and MKN 28 cells), incubated with different H. pylori strains. The levels of cPLA(2), mRNA, and protein expression were un changed in Hep-2 cells independently of cellular adhesion or invasion of th e 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 gastri c mucosae of patients with H. pylori infection and no change in epithelial cell lines exposed to H. pylori.