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

Production of interleukin 8 (IL-8) is believed to be important in the pathogenesis of the gastritis seen in Helicobacter pylori infection. T he aim of this study was to investigate the roles of protein kinase A (PKA), protein kinase C (PKC), protein tyrosine kinase (PTK) and intra cellular calcium in the induction of IL-8 production by gastric epithe lial cells. AGS gastric epithelial cells were stimulated with H. pylor i, tumour necrosis factor alpha or interleukin 1 beta together with ac tivators or inhibitors of the relevant kinases. IL-8 production was me asured by enzyme-linked immunosorbent assay. Helicobacter pylori, tumo ur necrosis factor alpha and interleukin 1 beta produced a dose-depend ent increase in IL-8 production, The increase with all three, was sign ificantly reduced by the tyrosine kinase inhibitors herbimycin A and g enistein. Activation of PKC by phorbol myristate acetate was also an e ffective stimulus to IL-8 production and this was blocked by PKC deple tion or inhibitors. Protein kinase C inhibition did not reduce the sti mulation produced by ii. pylori or the cytokines. Stimulation of PKA w ith forskolin or dibutyryl cyclic adenosine monophosphate or inhibitio n with H89 had no effect on IL-8 production. The calcium ionophore A23 187 was a weak, PKC dependent, stimulant of IL-8 production. The produ ction of IL-8 in AGS cells is stimulated via tyrosine kinase and prote in kinase C dependent pathways. Stimulation by H. pylori, tumour necro sis factor alpha and interleukin 1 beta requires tyrosine kinase activ ity. (C) 1997 Academic Press Limited.