Multiple genes in the left half of the cag pathogenicity island of Helicobacter pylori are required for tyrosine kinase-dependent transcription of interleukin-8 in gastric epithelial cells

Helicobacter pylori strains that contain the cag pathogenicity island (PAT) elicit increased synthesis of gastric C-X-C chemokines, promote neutrophil ic infiltration into the gastric epithelium, and stimulate the synthesis of interleukin-8 (IL-8) in cultured gastric epithelial cells. To investigate the effects of cag PAT genes on the transcription of the IL-8 gene, the Kat o-3 gastric epithelial cell line was stably transfected with plasmid DNA co ntaining the IL-8 gene promoter fused to a luciferase reporter gene. The re sulting reporter cell line, L5F11, was used to monitor the effects of infec tion in cell culture by H. pylori 26695 and isogenic derivatives with null mutations in genes in the cag PAT on transcription of the IL-8 gene. We fou nd that null mutations in eight open reading frames, including homologs of the Agrobacterium virB9, virB10, and virB11 genes, in the left half of the cag PAT abrogated the induction of IL-8 gene transcription. Further studies with the L5F11 cell line showed that IL-8 gene transcription induced by H. pylori was blocked by the protein tyrosine kinase inhibitor herbimycin A b ut not by the protein kinase C inhibitor calphostin C or by the protein kin ase G inhibitor KT5823. IL-8 gene transcription in L5F11 cells could also b e induced by the cytokine tumor necrosis factor alpha (TNF-alpha) without e xposure to H. pylori. This TNF-alpha-induced IL-8 transcription was inhibit ed by the protein kinase A inhibitor H7, which had no significant effect on H. pylori-induced IL-8 transcription. These studies show that multiple gen es in the left half of the cag PAI are essential for the transcription of t he IL-8 gene in gastric epithelial cells and that this depends on protein t yrosine kinase activation.