A possible role of IL-1RN gene polymorphism in the outcome of gastrointestinal diseases associated with H. pylori infection

Rejane Mattar,1 Sergio Barbosa Marques,1 Anibal Ferreira dos Santos,1 Maria do Socorro Monteiro,1 Kiyoshi Iriya,2 Flair José Carrilho1 1Department of Gastroenterology, University of S o Paulo School of Medicine, S o Paulo, SP, Brazil; 2Department of Pathology, University of S o Paulo School of Medicine, S o Paulo, SP, Brazil Objective: To verify whether the variable number of tandem repeat (VNTR) polymorphism in the IL-1RN gene that encodes the interleukin (IL)-1 receptor antagonist (IL-1Ra) plays a role in the outcome of gastrointestinal diseases associated with Helicobacter pylori (H. pylori) infection. Methods: Patients with normal endoscopy (n = 71), inflammation of the upper gastrointestinal tract only (n = 196), gastric ulcer (n = 28), duodenal ulcer (n = 76), and gastric cancer (n = 19) were studied. H. pylori infection was diagnosed by the urease test, histological examination, and polymerase chain reaction. The IL-1 receptor antagonist gene (IL-1RN intron 2 VNTR) was analyzed by polymerase chain reaction. Gastritis was scored according to the updated Sydney system of classification. Results: H. pylori infection was an independent risk factor for mild (odds ratio [OR] = 5.53 [95% confidence interval [CI] = 2.63–11.64; P < 0.05]), moderate (OR = 83.93 [95% CI = 29.7–237.18; P < 0.05]) and marked (OR = 47.47 [95% CI = 5.39–418.05; P < 0.05]) gastritis. The carriage of IL-1RN*2/*2 had a significant protective effect of H. pylori infection (OR = 0.31 [95% CI = 0.17–0.57; P < 0.05]). H. pylori infection was identified as an independent risk of inflammation, duodenal ulcer, and gastric ulcer. The carriage of IL-1RN*2/*2 was an independent risk factor for gastric cancer (OR = 5.81 [95% CI = 1.06–31.98; P < 0.05]); nonetheless, the carriage of allele 2 (IL-1RN*2/*2 plus IL-1RN*L/*2) had an independent protective effect on duodenal ulcer (OR = 0.45 [95% CI = 0.22–0.91; P < 0.05]). Conclusions: Allele 2 of the VNTR IL-1RN polymorphism had a protective effect against duodenal ulcer and H. pylori infection; however, it increased the risk of gastric cancer. Keywords: Helicobacter pylori, IL-1RN polymorphism, gastric cancer, peptic ulcer