Circulating microRNA146b-5p is superior to C-reactive protein as a novel biomarker for monitoring inflammatory bowel disease

Background Owing to the importance of early treatment, simple and reliable methods for monitoring inflammatory bowel disease (IBD) are needed. Aims To determine whether circulating microRNAs are reliable biomarkers for IBD monitoring. Methods Serum levels of 17 candidate microRNAs were measured by quantitative real-time polymerase chain reaction in a discovery cohort (n = 120). Differentially expressed serum microRNAs were further investigated in an independent training cohort (n = 341). Correlations between relative microRNA levels and disease activity were evaluated. A disease control group was included to investigate the specificity of microRNA. Logistical regression was used to construct a microRNA classifier to identify endoscopic activity. Its predictive value was explored in the validation cohort (n = 66) using the area under the receiver operating characteristic curve (AUC). Results Serum microRNA146b-5p (miR-146b-5p) expression was 2.87- and 2.72-fold higher in patients with Crohn's disease and ulcerative colitis, respectively, than in healthy controls. Serum miR-146b-5p was significantly correlated with disease activity and was more specific than C-reactive protein (CRP). A classifier was built for Crohn's disease, ie P [Endoscopically active] = 11+e2.937-0.737(miR-146b-5p)-0.008PLT, with a greater AUC of 0.869 [0.764-0.940] than that for CRP (0.680 [0.554-0.790]) (P = 0.0043). Conclusions MiR-146b-5p may better reflect mucosal inflammation in IBD than CRP. The Crohn's disease classifier developed in this study may be valuable for identifying endoscopic activity in patients with Crohn's disease.