Altered microRNA expression in inflamed and non‐inflamed terminal ileal mucosa of adult patients with active Crohn's disease

MicroRNAs (miRNAs) play an important role in inflammation. Several studies have reported the unique miRNA profiles in colonic mucosa and peripheral blood of patients with active Crohn's disease (CD). But there is limited data about the miRNA profiles of the terminal ileum, the most commonly involved location, especially the non-inflamed mucosa. We aimed to investigate the miRNA expression of both inflamed and non-inflamed terminal ileal mucosa in adult patients with active CD.Total RNA of all mucosal samples was extracted. MiRNA expression profile was assessed using microarray technology, and then selected miRNAs were evaluated using quantitative reverse-transcription polymerase chain reaction (qRT-PCR) to confirm the results of the microarray investigation.Sixteen CD patients and 10 healthy adults were included. Samples of six patients and six controls were used for the microarray analysis. Samples of all participants were used for the validation of qRT-PCR. Results of the microarray showed miRNA expressions of both inflamed and non-inflamed mucosa were altered compared with controls. The differential expressions of hsa-miR-192-5p, hsa-miR-495-5p, hsa-let-7b-5p, hsa-miR-361-3p, and hsa-miR-124-3p were confirmed by qRT-PCR.Both inflamed and non-inflamed terminal ileal mucosa in adult patients with active CD have their distinct miRNA expression patterns compared with healthy controls. Dysregulated miRNAs may be responsible for pathogenesis of CD.