Helicobacter infection and phospholipase A2 enzymes: Effect of Helicobacter felisa[euro]infection on the expression and activity of sPLA2 enzymes in mouse stomach

The murine gastric mucosa possesses very high secretory type phospholipase A sub(2) activity. Northern and Western blots indicated that the pancreatica[euro]type, sPLA sub(2)a[euro]IB represents the predominant form of sPLA sub(2) enzymes present in the gastric mucosa. Both sPLA sub(2)a[euro]IB mRNA and protein in the gastric mucosa exceeded levels found in the pancreas, and in contrast to the pancreatic enzyme it was present primarily in the active state. The sPLA sub(2)a[euro]IB gene is not expressed in the murine small intestine and colon. Infection by the gastritis-inducing bacteria, Helicobacter felis (H. felis) dramatically and time dependently decreased the PLA sub(2) activity in the glandular stomach of the mouse strain, C57BL/6, sensitive to the organism, which appeared to be related to a decrease in the percentage of sPLA sub(2)a[euro]IB present in the active form. This bacterial-induced reduction in PLA sub(2) activity was not observed in BALB/c mice that fail to develop gastritis in response to H. felis infection. C57BL/6 mice do not, while BALB/c mice express, the PLA sub(2)a[euro]II enzyme. The H. felisa[euro]induced reduction in sPLA sub(2)a[euro]IB activity may weaken the gastric barrier by reducing the local concentration of arachidonic and linoleic acid, liberated from membrane phospholipids, the major precursors of 'cytoprotective' prostaglandins. Data presented here suggest that both sPLA sub(2)a[euro]IB and sPLA sub(2)a[euro]II enzymes may contribute to the gastric response to Helicobacter infection.