Expression of cytosolic phospholipase A2 and Helicobacter pylori infection: In vivo and in vitro study

Modifications of mucosal phospholipids have been detected in Helicobacter pylori (H. pylori) positive gastritis. These alterations appear secondary to increased phospholipase A2 activity (PLA2). The cytosolic form of this enzyme (cPLA2), normally involved in cellular signaling and growth, has been implicated in cancer pathogenesis. We recently investigated cPLA2 expression and PLA2 activity in the gastric mucosa of patients with and without H. pylori infection. The molecular levels of cPLA2 (RNA by RT-PCR and protein by immunohistochemistry) and total PLA2 activity were higher in patients with H. pylori infection than in uninfected patients. To clarify whether H. pylori affected cellular expression of cPLA2 directly we studied cPLA2 expression in vitro using human epithelial cell lines from larynx carcinoma (i.e. HEp-2 cells) incubated with different H. pylori strains. The levels of cPLA 2 (mRNA and protein expression by northern and western blot analyses, respectively) were unchanged in Hep-2 cells independently of bacterial virulence. In conclusion, our study shows increased cPLA2 expression and PLA2 activity in the gastric mucosa of patients with H. pylori infection while no change is observed in epithelial cell lines exposed to H. pylori. The increase in cPLA2 in vivo but not in vitro suggests that systemic events specifically related to H. pylori infection may play a key role in this up-regulation.