Faecal Micro-RNAs in Inflammatory Bowel Diseases

Abstract Background and Aims Faecal biomarkers are used as indicators of disease activity in inflammatory bowel diseases [IBD], which include Crohn’s disease [CD] and ulcerative colitis [UC]. Micro-RNAs [miRNAs] are small non-coding RNAs detectable in extracellular fluids and can be used as clinical biomarkers. The aim of this study was to determine if faecal miRNA composition is altered in IBD. Methods More than 800 different human faecal miRNAs were measured in stool samples from control individuals and patients with active CD by using NanoString technology. Selected miRNAs were quantified by qRT-PCR in faeces, serum and intestinal tissue of controls [n = 23] and patients with inactive or active CD [n = 22, n = 22] or UC [n = 11, n = 24] as well as patients with Clostridium difficile infection [CDI, n = 8]. Results In total, 150 miRNAs were significantly detected in faeces from controls and patients, and multivariate analyses showed that CD patients with high disease activities had a distinct miRNA profile and that miR-223 and miR-1246 were distinct from other faecal miRNAs. In a larger cohort, active UC patients displayed significantly higher levels of miR-223 and miR-1246 than controls while patients with CDI had higher levels of faecal miR-1246 but not miR-223. No differences were noted in serum samples. Conclusions To our knowledge, this is the first comprehensive screen of faecal miRNAs performed in IBD. Further investigation will aim to confirm these findings in a larger cohort and to understand the biological function and cellular sources of faecal miRNAs.