microRNA profiling in duodenal ulcer disease caused by Helicobacter pylori infection in a Western population.

Although the connection of microRNAs (miRNAs) to some diseases is well established, their involvement in chronic infections such as Helicobacter pylori has received less attention. The aim was to compare miRNA expression profiling in patients with duodenal ulcer (DU) due to H. pylori infection with that in infected patients without DU and in uninfected patients. The miRNA expression profile was determined by microarrays in antral mucosal samples from well-characterized dyspeptic patients (n = 46). The most significant set of miRNAs was subsequently analysed in an independent validation group of patients (n = 42). Transcripts for IL8, IL12p40, IL12p35 and IL23p19, the signalling molecules MYD88, GATA6, SOCS2 and STAT6 and H. pylori virulence factors cagA and VacA were analysed. Microarray experiments showed that 17 miRNAs were deregulated in the mucosa of H. pylori-infected patients. No significant differences were observed between normal and DU patients. PCR confirmed the up-regulation of miR-9, miR-146a, miR-155 and miR-650 and the down-regulation of miR-96 and miR-204 in the independent validation set of patients. Importantly, miR-9, miR-96, miR-146a and miR-650 expression was specific to chronic-active gastritis. H. pylori-infected patients showed higher levels of IL8 and IL12p40 mRNAs and lower levels of GATA6 and SOCS2 mRNAs. The antral mucosa of patients with non-active or chronic-active gastritis showed significantly lower levels of GATA6, MYD88, SOCS2 and STAT6 mRNAs compared with patients without gastritis. The down-regulation of these factors was not correlated with the expression of any of the validated miRNAs. The exact role of the miRNA changes observed will require further study.