Production of IL-12 in gastritis relates to infection with Helicobacter pylori

Increased production of proinflammatory cytokines, including tumour necrosis factor-alpha (TNF-alpha), IL-1beta, IL-6 and IL-8, has been demonstrated in Helicobacter pylori-associated gastric mucosal inflammation. IL-12, a newly characterized cytokine, is thought to be a key mediator in host responses to bacterial infections. The aim of this study was to investigate differences in cytokine patterns between H. pylori-positive and -negative gastritis and normal mucosa. Secretion of IL-12, TNF-alpha, IL-1beta, IL-6, IL-8 and IL-10 was measured in 176 patients with chronic gastritis in whole biopsy cultures. Gastritis was graded for chronic inflammation or acute inflammatory activity, respectively, according to the Sydney system. Biopsies with similar scores were matched for analysis from H. pylori-infected and non-infected patients. Secretion of IL-12 was significantly increased in H. pylori-associated gastritis in comparison with H. pylori-negative gastritis (P < 0.0001). In contrast, secretion of TNF-alpha, IL-1beta, IL-6, and IL-8 correlated with the degree of inflammation but was not different between H. pylori-positive and -negative patients. Moreover, IL-10 secretion was found to be higher in H. pylori-positive than in H. pylori-negative patients. IL-12 may play a specific role in H. pylori-associated gastric disease, whereas production of the proinflammatory cytokines TNF-alpha, IL-1beta, IL-6 and IL-8 does not seem to be restricted to H. pylori-induced inflammation. The contra-inflammatory cytokine IL-10 may be a contributor to the chronicity of H. pylori-associated gastritis by impairing clearance of the pathogen.