THE MUCOSAL MICRORNA PROFILE RELATES TO AGE AND SEVERITY OF DISEASE IN PATIENTS WITH ULCERATIVE COLITIS

Despite significant evidence that the expression of several microRNA’s (miRNA) impacts on disease activity in patients with ulcerative colitis (UC), it remains unknown if the more severe disease phenotype seen in pediatric-onset UC can be explained by altered miRNA expression. In this study, we aimed to assess the relationship between miRNA expression, age, and disease severity in pediatric and adult patients with UC. Using RT-qPCR, we analyzed the expression of miR-21, miR-31, miR-126, miR-142, and miR-155 in paraffin-embedded rectum biopsies from 30 pediatric and 30 adult-onset UC patients, and found that lesions from adult patients had significantly higher expression levels of miR-21 compared to pediatric patients and that the expression levels of miR-31 (all patients) and miR-155 (pediatric patients only) correlated inversely with histological assessed disease severity. Using in situ hybridization followed by image analysis, the expression estimates of miR-21 and miR-126 were found to correlate with histological assessed disease severity. In conclusion, we found that the expression of miRNAs depends on the age of the patient and/or the severity of the disease, suggesting that miRNAs may contribute to the regulation of inflammation in UC and could be useful biomarkers in the surveillance of disease severity.