Tissue and Circulating MicroRNA-31, MicroRNA-200b, and MicroRNA-200c Reflects Disease Activity in Crohn's Disease Patients: Results from the BIOMIR Study.

Background and aims: MicroRNAs (miR) have altered expression in multiple autoimmune disorders including inflammatory bowel disease. The aim of the study was to assess the tissue and circulating miR-31, miR-200b, and miR-200c expression levels as potential biomarkers for intestinal disease activity in patients with Crohn's disease (CD).

Methods: The study included 45 patients with histopathological confirmed CD and active disease (defined as fecal calprotectin >50 μg/g and Simple Endoscopic Score (SES) of CD >3), and 21 subjects as controls for the validation cohort. Demographic and clinical data, biomarkers (fecal calprotectin), endoscopy data, the expression levels of miR-31, miR-200b, and miR-200c in tissue and serum were assessed (by RT-PCR). Receiver operating characteristic analysis was performed to assess the miR-31, miR-200b, and miR-200c expression levels as potential biomarkers for active CD.

Results: Mean fecal calprotectin was 1540±890 μg/g. Mean SES-CD was 8.9±4.2. Tissue and circulating miR- 31 were significantly correlated with fecal calprotectin (r=0.81, r=0.83, p<0.01) and with SES-CD (r=0.82, r=0.79, p<0.01). The expression level of miR-31 was significantly upregulated in CD tissue cases compared to the control tissue samples (6.24±1.57 vs. 3.70±1.44; p <0.01). Similarly, serum miR-31 expression levels in CD patients were significantly upregulated compared to the control serum samples (0.78±0.42 vs. -2.07±1.00; p<0.01). The expression levels of tissue miR-200b and miR-200c were significantly upregulated in CD tissue cases compared to the control tissue samples (-5.25±0.93 vs. -4.69±0.80, p=0.03 for miR-200b, and -0.86±0.96 vs. 0.39±0.66, p<0.01 for miR-200c). Similarly, serum miR-200b and miR-200c expression levels in CD patients were significantly upregulated compared to the control serum samples (p < 0.05). Receiver operating characteristic analysis revealed that the expression levels of the selected miRNAs could help to discriminate active CD patients from healthy controls with very good specificity and sensitivity.

Conclusions: Tissue and circulating miR-31, miR-200b, and miR-200c reflect disease activity in CD patients and can be used as biomarkers for active disease.