Fecal miR-223 is a noninvasive biomarker for estimating Crohn's disease activity.

Introduction: MicroRNA-223 (miR-223) has emerged as a promising noninvasive biomarker for Crohn's disease (CD). However, it is unclear which tissue derived miRNA-223 can more accurately estimate CD disease activity.

Materials And Methods: To collect serum, terminal ileal mucosa biopsy and fecal samples from CD patients and healthy controls. The CD Activity Index (CDAI) score, Montreal classification, maintenance medicines, peripheral blood inflammatory markers, fecal calprotectin (FC) and the Simple Endoscopic Score for CD (SES-CD) were recorded. To compare the expression of miR-223 in the serum, intestinal tissue, and feces.

Results: MiR-223 expression levels in the serum, intestinal tissue and feces of CD patients were significantly higher than those of controls. The level of miR-223 in the serum, intestinal tissue and feces increased significantly in active CD patients compared with that in inactive CD patients. The levels of serum, intestinal tissue and fecal miR-223 were correlated with the CDAI. Serum miR-223 was also correlated with C-reactive protein (CRP) and IL-6, tissue miR-223 correlated with IL-6 and FC, and fecal miR-223 correlated with FC. In terms of the association with FC, fecal miR-223 had a higher Spearman r value than tissue miR-223. The area under the curve (AUC) values of serum, tissue and fecal miR-223 to diagnose CD were similar to those of CRP and FC (AUC > 0.8). The AUC values of tissue and fecal miR-223 to evaluate CD disease activity were 0.832 and 0.818, respectively, and were higher than serum miR-223, CRP and FC. Fecal miR-223 had a higher specificity of 92.3%.

Conclusions: Fecal miR-223 might be a novel, noninvasive biomarker for estimating the disease activity of CD patients.