Interweaving microRNAs and proinflammatory cytokines in gastric mucosa with reference to H. pylori infection.

Using endoscopic biopsies, gastric mucosal expression levels of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-alpha (TNF-α) messenger RNA (mRNA) and microRNAs (miRNAs) that were differentially expressed in association with Helicobacter pylori were assessed by quantitative reverse-transcriptase polymerase chain reaction. Among the H. pylori-positive mucosa, 17 out of 29 miRNAs had significant correlations with at least one of the four proinflammatory cytokines in expression. Among the 17 miRNAs, 15 were associated with the degree of neutrophil infiltration and, more prominently, the degree of mononuclear cell infiltration, according to the updated Sydney system. Persistent H. pylori infection may affect the mucosal expression profiles of miRNAs via chronic inflammation mediated by proinflammatory cytokines. There were significant positive correlations between certain miRNAs including the microRNA-200 family and IL-1β, IL-6, or TNF-α mRNA in H. pylori-negative gastric mucosa. Underscoring the causal association between miRNAs and proinflammatory cytokines may provide insights into the pathogenesis of H. pylori-associated gastritis linking to gastric carcinogenesis.