FECAL MICRO-RNA SCREENING IN CROHN'S DISEASE PATIENTS

Background: micro-RNA (miRNA) are small non-coding RNAs that regulate numerous intracellular functions. Owing to relatively long persistence in extracellular environments and tightly regulated expressions, miRNA are good clinical biomarkers. In this study, we measured the expression of 800 different human miRNA in stool samples from controls and Crohn's disease patients. Material/Methods: Stool samples were obtained from 6 active Crohn's disease patients with ileal involvement and 6 healthy age- and sex-matched controls. Stool samples were weighted, diluted in distilled water and homogenized in Trizol®, and total RNA was extracted by the phenol/chloroform method followed by precipitation and purification with phenol-free columns. A₂₆₀/A₂₈₀ and A₂₆₀/A₂₃₀ RNA purity ratio were 2,02(± 0,05) and 1,86(±0,21), respectively. miRNA screening was performed using the human miRNA Expression Assay kit (Nanostring) following the recommended protocol. Results: Of the 800 measured miRNA, the analysis was restricted to 95 miRNA with levels higher than the background (4 times higher in all samples or 8 times higher in any sample). Cluster analyses indicate the existence of distinct groups of fecal miRNA depending on their abundance in patients as compared to controls (more, less, or equally abundant). Patients with the most severe diseases displayed distinct miRNA profiles, and the most highly detectable fecal miRNA in Crohn's disease patients vs. controls was miR-223. Conclusions: To our knowledge, this is the first fecal miRNA screen performed in IBD. Further investigation will aim at confirming these findings in a bigger cohort, and at understanding the biological function and cellular sources of the detected miRNA