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

Background & Aims: 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 the study was to investigate the relationship between cagA gene and cytokine messenger RNA (mRNA) expression in gastric mucosa. Methods: 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. Results: 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 gen-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. Conclusions: 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.