No serum miRNA was regulated exclusively in aUC compared with iUC patients. Four miRNAs were higher and three miRNAs

were lower in the mucosa of aCD than iCD. Two miRNAs were higher and three miRNAs were lower in the mucosa of aUC than iUC. No serum miRNAs coincided with tissue miRNAs in aCD and aUC patients. Our results suggest Decitabine in vivo the existence of specific miRNA expression patterns associated with IBD and their different stages and support the utility of miRNA as possible biomarkers. This pilot study needs to be validated in a large prospective cohort. Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is a chronic inflammatory gastrointestinal disorder, the pathophysiology of which remains unclear. The theory accepted most commonly is that IBD

and the associated gastrointestinal inflammation are likely to be the result of the interaction between a defective immune response to a luminal factor (probably intestinal flora), epigenetic and environmental factors (e.g. smoking) and its influence in genetically predisposed subjects [1-3]. Genetic factors involved in inflammation and immune functions are known to play a very important role in IBD physiopathology. Micro-RNAs (miRNAs) are a class of small non-coding RNAs, involved in the control of gene expression at the post-transcriptional level [4]. Following the discovery of miRNAs, the number of publications regarding their biogenesis and functions has been increasing exponentially and the miRNA sequence database, miRBase, is growing continuously [5, 6].

BVD-523 mouse MiRNAs are involved in the regulation of many biological processes such as the cell cycle, differentiation, Exoribonuclease proliferation, apoptosis, fibrosis and immune function [7]. Emerging evidence has demonstrated that miRNAs can also play an important role in the development of cancer as well as in the induction of chronic inflammatory and autoimmune diseases [8, 9]. miRNAs have been found in tissues, serum, plasma and other body fluids. It has been demonstrated that the levels of miRNAs in serum are stable, reproducible and consistent among individuals of the same species [10]; for this reason, such levels are now being used as a non-invasive biomarker for different pathologies (i.e. cancer, autoimmune disease, inflammation) [10, 11]. Previous studies, focused particularly on cancer, have discovered that circulating miRNA profiles can be correlated with tissue miRNA profiles [12, 13]. In most cases, those changes in circulating miRNA profiles can precede the standard blood biomarkers and possess prognostic value [12, 14, 15]. These properties mean that miRNAs are attractive, blood-based, non-invasive biomarkers. Recently, several papers have focused investigation on the altered expression of miRNAs in IBD and their important role as regulators and possible diagnostic biomarkers in IBD [8, 16-18].