The Role of MicroRNA in Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is the consequence of an abnormal immune response to environmental factors in genetically susceptible hosts. microRNAs (miRNAs) are small, 22-nucleotide, noncoding, single-stranded RNA molecules involved in the post-tran-scriptional regulation of 30% of protein-coding genes. Differential expression of miRNAs is described in multiple autoimmune-related conditions such as psoriasis, rheumatoid arthritis, lupus, and asthma. Recently, unique miRNA expression profiles have been described in epithelial cells of patients with active ulcerative colitis, Crohn's ileitis, and Crohn's colitis, as well as in the peripheral blood of patients with active ulcerative colitis and Crohn's disease. miRNA expression profiles also change in the progression from normal colonic tissue to dysplastic tissue, with unaffected tissue from IBD patients and inflamed tissue from IBD patients showing intermediate profiles. Understanding the role of miRNAs in IBD may lead to future insights into disease pathogenesis, diagnosis, and treatment.