P003 MicroRNAs as biomarkers in Inflammatory Bowel Disease unclassified (IBDU) patient samples may predict the development from IBDU to Crohn’s Disease or Ulcerative Colitis

Abstract Background Differential diagnosis in Inflammatory Bowel Disease (IBD) is challenging; typically, discriminating Crohn’s Disease (CD) from Ulcerative Colitis (UC) among IBD unclassified (IBDU) patients is a diagnostic encounter in cases where the inflammatory lesions are restricted to the colon. MicroRNAs are found to be involved in the pathogenesis and are also evaluated as diagnostic biomarkers and therapeutic targets in IBD. Methods We obtained formalin fixed paraffin embedded (FFPE) colonic mucosal biopsies of 35 IBDU patients (including adults and children), and 8 IBD (4 CD and 4 UC) patients who were classified into CD or UC collected from the diagnostic endoscopy. Based on the patient charts, The IBDU samples were reclassified into CDs or UC or remained as IBDU after minimum 3 years clinical follow up, ie. 12 IBDU patients were reclassified as CD (IBDU-CD) and 15 IBDU patients as UC (IBDU-UC). Eight IBDU patients remained as IBDU. MicroRNA profiling was performed on all samples using Affymatrix GeneChip miRNA Arrays. Arrays were processed using pd.mirna.4.0 and oligo packages in R and were analysed using LIMMA package. Results We found that miR-3176 and miR-182-5p were upregulated in IBDU-CD and miR-671-5p, miR-668-5p, miR-4793-3p, and mir-6776 were upregulated in IBDU-UC with p values of less than 0.05 and 1< log [fold change] <-1 for all 6 microRNAs. Higher mucosal expression levels of miR-3176 and miR-182-5p in IBDU-CD samples compared to IBDU-UC samples, resulted in an area under the curve (AUC) of 0.87 (95% confidence interval (CI), 0.71 – 1.00) and 0.81 (CI, 0.63 – 1.00), respectively, in discriminating IBDU-CD from IBDU-UC. On the other hand, miR-3176 and miR-182-5p had AUCs of 0.69 (CI, 0.25-1.00) and 0.69 (CI, 0.21-1.00), respectively, in discriminating CD and UC. MicroRNA miR-671-5p had a higher AUC of 0.81 (CI, 0.48 - 1.00) for discriminating CDs and UCs, whereas in discriminating IBDU-CD and IBDU-UC, the AUC was only 0.64 (CI, 0.42 – 0.87). Conclusion We conclude that differential microRNA expression among IBDU patients can predict the development of IBDU to CD and IBDU to UC, and that the microRNA expression profile of IBDU patients differ from patients classified as CD or UC at time of diagnosis. Our findings suggest that IBDUs may have different pathogenic mechanisms for IBDU-CDs and IBDU-UCs.