P001 MicroRNA-155-5p contributes to the development of Ulcerative Colitis by regulating T lymphocyte proliferation and functions

Abstract

Abstract Background MicroRNA (miRNA) is a small non-coding RNA which regulate a variety of cell functions by suppressing target mRNAs in a post-transcriptional manner. Recent works have identified an increased expression of miR-155-5p in the colonic mucosa of UC patients. However, the role of miR-155-5p in the pathophysiology of UC remains understudied. This study aims to clarify the role of miR-155-5p in development of colitis in UC patients. Methods MiRNA and mRNA expression profiles in colon were compared between 15 UC and 5 healthy controls by running small RNA-sequencing (smRNA-Seq) and RNA-Seq on the matched colon tissue. Candidate target genes of miR-155-5p were identified by analyzing sequencing data sets using a statistical simulation method (miRhub). MiR-155-5p expressing cells were identified by in situ hybridization in combination with immunohistochemistry on inflamed colon tissue of UC patients. The impact of miR-155-5p on colonic inflammation was tested in the dextran sulfate sodium (DSS) -induced colitis model using miR-155 deficient mice. Results MiR-155-5p expression was significantly higher in the inflamed colonic tissue of UC patients than in healthy controls with more pronounced up-regulation in the treatment refractory UC patients compared to the treatment naïve UC patients (UC vs. healthy controls, log2FC = 0.83, adjusted p-value = 0.014). MiRhub analysis identified 10 candidate target genes of miR-155-5p including SHANK2, MYO1D, ADD3, AHCYL2, NR3C2, MIER3, TRIM2, GPD1L, SEMA5A, and SATB2 most of which were involved in cell proliferation and immune response (NR3C2, MIER3, TRIM2, GPD1L, SEMA5A, and SATB2). In situ hybridization identified a group of CD3 positive T lymphocytes with increased miR-155-5p expression in the inflamed colonic mucosa. MiR-155 deficient mice showed attenuated DSS-induced inflammation in colon compared to the control wild type mice (colon weight/length ratio, miR-155 deficient mice vs. controls, 27.2 vs. 44.6, p<0.01). Conclusion MiR-155-5p may contribute to the development of colitis in UC by regulating T lymphocyte proliferation and functions.