Mechanism for Helicobacter pylori stimulation of interleukin-8 production in a gastric epithelial cell line (MKN 28): roles of mitogen-activated protein kinase and interleukin-1 beta

Although it is known that the pathogenic mechanism of Helicobacter pylori i nvolves the stimulated production of interleukin-8 (IL-8) as an inflammator y mediator, the details of the pathway remain unclear. The role of mitogen- activated protein kinase (MAPK) in IL-8 production by H. pylori has been ex amined in an in vitro study. IL-8 mRNA expression in gastric epithelial cel ls (MKN 28) was determined by reverse transcriptase-polymerase chain reacti on (RT-PCR). IL-8 production was examined by ELISA. The activation of p38 M APK was assessed by western blotting. Neither IL-8 mRNA nor activated p38 M APK or p44/42 MAPK was detected in cells not treated with H. pylori. In con trast, incubation of cells with H. pylori, or IL-1 beta, or both, clearly s timulated the expression of IL-8 mRNA within 60 min in a concentration-depe ndent manner. Phosphorylation of p38 MAPK and p44/p42 MAPK, as well as IL-8 production, occurred within 30 min and 24 hr after co-culturing MKN 28 cel ls with H. pylori and IL-IP, respectively Pretreatment of cells with MAPK i nhibitors [1-[7-(4-fluorophenyl)-1,2,3,4-tetra-hydro-8-pyridylpyrazolo[5, 1 -c][1,2,4]triazin-2-yl]-2-phenylethanedione sulfate monohydrate (FR167653), 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole (SB20 3580), or 2-(2 ' -amino-3 ' -methoxyphenyl)-oxanaphthalen-4-one (PD98059)] significantly inhibited IL-8 production stimulated by H. pylori or IL-1 bet a or both. The combination of H. pylori and IL-1 beta additively stimulated IL-8 production. The additive effect of H. pylori and IL-1 beta on IL-8 pr oduction was inhibited by treatment with a p38 MAPK inhibitor. It was revea led that the culturing of MKN 28 cells with H, pylori significantly stimula tes IL-8 production to a degree sufficient for induction of neutrophil chem otaxis via activation of p38 and p44/42 MAPK. (C) 2001 Elsevier Science Inc . All rights reserved.