Abstract

Background:Helicobacter pylori infection is associated with variable clinical outcomes, including gastroduodenal diseases, and genetic factors may be relevant in this process.

Aims: We investigated the effects of an interleukin 8 (IL-8) gene polymorphism on the risk of gastroduodenal diseases, the degree of H pylori induced gastritis, and IL-8 gene transcription.

Subjects: The study was performed in 244 healthy control subjects and 690 H pylori positive patients with non-cardia gastric cancer, gastric ulcer, duodenal ulcer, or gastritis.

Methods: We identified the IL-8 −251 A/T polymorphism by direct sequence analysis, and measured the gastritis score and serum pepsinogen (PG). The transcriptional promoter activity of the IL-8 gene was assessed by luciferase assay.

Results:IL-8 −251A was associated with a higher risk of gastric cancer and gastric ulcer. Patients carrying IL-8 −251A showed an increased risk of gastric cancer (odds ratios (OR) 2.01 (95% confidence interval (CI) 1.38–2.92)) and gastric ulcer (OR 2.07 (95% CI 1.37–3.12)). Compared with patients younger than 49 years, atrophy and metaplasia scores in the antrum were significantly higher and the PG I/II ratio significantly lower in −251A carriers than in T/T carriers. In the in vitro assay, IL-8 −251A showed enhanced promoter activity in response to IL-1β or tumour necrosis factor α.

Conclusions: The IL-8 −251A allele may be associated with progression of gastric atrophy in patients with H pylori infection, and may increase the risk of gastric cancer and gastric ulcer in Japanese people.