Helicobacter pylori cagA gene and expression of cytokine messenger RNA in gastric mucosa.

Helicobacter pylori strains possessing the cagA gene are thought to be associated with gastroduodenal diseases. Furthermore, some cytokines are considered to play a role in gastric mucosal inflammation. The aim of this study was to investigate the relationship between cagA gene and cytokine messenger RNA (mRNA) expression in gastric mucosa. In 160 patients, the cagA gene was detected using polymerase chain reaction, and interleukin (IL) 1 beta, IL-6, IL-7, IL-8, IL-10, and tumor necrosis factor (TNF) alpha mRNA were detected using reverse-transcription polymerase chain reaction. Specimens infected with cagA gene-positive strains (cagA-positive specimens) had significantly more severe infiltration of polymorphonuclear leukocytes and mononuclear cells than those infected with cagA gene-negative strains (cagA-negative specimens). Levels of expression of IL-6, IL-7, IL-8, IL-10, and TNF-alpha mRNA were significantly higher in H. pylori-positive than H. pylori-negative patients. Furthermore, the level of IL-8 mRNA expression was significantly higher in cagA-positive than cagA-negative specimens. cagA-positive strains induce the expression of IL-8 mRNA, suggesting that IL-8 may play important roles in the pathogenesis of gastroduodenal diseases associated with H. pylori infection.