Association between interleukin-1β and tumor necrosis factor-α polymorphisms and symptoms of dyspepsia

Interleukin (IL)‑1β, and tumor necrosis factor (TNF)‑α have significant roles in the mediation of inflammatory immune responses and are also potent inhibitors of gastric acid secretion in the stomach. The present study aimed to investigate the associations between polymorphisms at position ‑31 (T>C) of the IL‑1β gene and ‑857 (C>T) of the TNF‑α gene with dyspeptic symptoms. Polymorphisms at position ‑31 (T>C) of the IL‑1β gene and ‑857 (C>T) of the TNF‑α gene were genotyped in 261 subjects, including 126 subjects without symptoms and 135 subjects exhibiting symptoms of dyspepsia. The IL‑1β ‑31 CC genotype was inversely associated with dyspeptic symptoms in all subjects, as determined by the Fisher's exact test [odds ratio (OR), 0.57; 95% confidence interval (CI), 0.34‑0.96; P=0.046]; however, this association was not detected following logistic regression analysis. Within the subgroups of symptoms, the CC genotype was also inversely associated with upper abdominal pain (OR, 0.28; 95% CI, 0.12‑0.67; P=0.003) and epigastric pain syndrome (EPS)‑like symptoms (OR, 0.14; 95% CI, 0.07‑0.28; P=0.003), according to the Rome III classifications. These associations were also found following logistic regression analysis (upper abdominal pain: OR, 0.34; 95% CI, 0.14‑0.80; P=0.014; and EPS‑like symptoms: OR, 0.41; 95% CI, 0.20‑0.84; P=0.015). No significant associations were identified between the TNF‑α ‑857 polymorphism and dyspeptic symptoms, including amongst the various subtypes analyzed. In conclusion, the IL‑1β ‑31 CC genotype was inversely associated with susceptibility to dyspeptic symptoms, in particular, upper abdominal pain and EPS‑like symptoms.