Circulating MicroRNA in inflammatory bowel disease.

BACKGROUND MicroRNAs (miRNAs) consist of a group of small noncoding RNAs that partially regulate gene expression. We investigated the expression patterns of commonly deregulated miRNAs in Crohn's disease (CD) and ulcerative colitis (UC) in peripheral blood samples of inflammatory bowel disease patients. PATIENTS AND METHODS This study consisted of 128 CD and 88 UC patients, as well as 162 healthy controls. The expression patterns of the miRNA species were quantitatively assayed using reverse transcription and real-time RT-PCR. Stem-loop complementary DNAs (cDNAs) were synthesized using looped reverse transcription primers specific for each miRNA. RESULTS MiR-16, miR-23a, miR-29a, miR-106a, miR-107, miR-126, miR-191, miR-199a-5p, miR-200c, miR-362-3p and miR-532-3p were expressed at significantly higher levels in the blood from patients with CD compared with the healthy controls. No significant differences were observed when the CD patients were classified according to disease location and phenotype. In the UC cases three miRNAs (miR-16, miR-21, miR-28-5p, miR-151-5p, miR-155 and miR-199a-5p) were significantly increased compared to healthy controls. miR-155 was the most highly expressed of the UC-associated miRNA in blood samples. CONCLUSIONS Our results suggest that several miRNAs could distinguish CD from UC by real-time PCR. This further highlights the putative role of miRNAs as contributors to IBD pathogenesis. They may help develop new non-invasive biomarkers to distinguish UC and CD.