STIMULATION OF IL-8 PRODUCTION IN HUMAN GASTRIC EPITHELIAL CELLS BY HELICOBACTER PYLORI, IL-1β AND TNF-α REQUIRES TYROSINE KINASE ACTIVITY, BUT NOT PROTEIN KINASE C

Abstract

Production of interleukin 8 (IL-8) is believed to be important in the pathogenesis of the gastritis seen in Helicobacter pyloriinfection. The aim of this study was to investigate the roles of protein kinase A (PKA), protein kinase C (PKC), protein tyrosine kinase (PTK) and intracellular calcium in the induction of IL-8 production by gastric epithelial cells. AGS gastric epithelial cells were stimulated with H. pylori, tumour necrosis factor α or interleukin 1β together with activators or inhibitors of the relevant kinases. IL-8 production was measured by enzyme-linked immunosorbent assay. Helicobacter pylori, tumour necrosis factor α and interleukin 1β produced a dose-dependent increase in IL-8 production. The increase with all three was significantly reduced by the tyrosine kinase inhibitors herbimycin A and genistein. Activation of PKC by phorbol myristate acetate was also an effective stimulus to IL-8 production and this was blocked by PKC depletion or inhibitors. Protein kinase C inhibition did not reduce the stimulation produced by H. pylorior the cytokines. Stimulation of PKA with forskolin or dibutyryl cyclic adenosine monophosphate or inhibition with H89 had no effect on IL-8 production. The calcium ionophore A23187 was a weak, PKC dependent, stimulant of IL-8 production. The production of IL-8 in AGS cells is stimulated via tyrosine kinase and protein kinase C dependent pathways. Stimulation by H. pylori, tumour necrosis factor α and interleukin 1β requires tyrosine kinase activity.