Interaction between inflammatory mediators and miRNAs in Helicobacter pylori infection.

Helicobacter pylori cause chronic inflammation favouring gastric carcinogenesis, and its eradication may prevent malignant transformation. We evaluated whether H. pylori infection and its eradication modify the expression of inflammatory mediators in patients with chronic gastritis. Furthermore, we assessed whether microRNAs modulate inflammatory pathways induced by H. pylori and identified miRNA-gene interaction networks. mRNA and protein expression of TNFA, IL6, IL1B, IL12A, IL2 and TGFBRII and miRNAs miR-103a-3p, miR-181c-5p, miR-370-3p, miR-375 and miR-223-3p were evaluated in tissue samples from 20 patients with chronic gastritis H. pylori negative (Hp-) and 31 H. pylori positive (Hp+), before and three months after bacterium eradication therapy, in comparison with a pool of Hp- normal gastric mucosa. Our results showed that H. pylori infection leads to up-regulation of TNFA, IL6, IL12A and IL2 and down-regulation of miRNAs. Bacterium eradication reduces the expression of TNFA and IL6 and up-regulates TGFBRII and all investigated miRNAs, except miR-223-3p. Moreover, transcriptional profiles of inflammatory mediators and miRNAs after eradication are different from the non-infected group. Deregulated miRNA-mRNA interaction networks were observed in the Hp+ group before and after eradication. Therefore, miRNAs modulated cytokine expression in the presence of H. pylori and after its eradication, suggesting that miRNAs participate in the pathological process triggered by H. pylori in the gastric mucosa.