P057. Micro-RNA expression profiling identifies miR-29b as a relevant pro-fibrogenic factor in Crohn's disease intestinal strictures
P. Biancheri1, A. Nijhuis2, A. Di Sabatino3, C. Lai2, A. Ghosh2, T.T. MacDonald1, G.R. Corazza3, J. Lindsay2, A. Silver2, 1Blizard Institute, Barts and The London School of Medicine and Dentistry, Centre for Immunology and Infectious Disease, London, United Kingdom, 2Blizard Institute, Barts and The London School of Medicine and Dentistry, Centre for Digestive Diseases, London, United Kingdom, 3Fondazione IRCCS Policlinico S. Matteo, University of Pavia, First Department of Medicine, Pavia, Italy
Intestinal fibrosis is a frequent complication in Crohn's disease (CD), with subsequent stricture development that may require surgical intervention. MicroRNAs (miRNAs) are a novel class of post-transcriptional gene regulators implicated in cardiac, hepatic and pulmonary fibrosis. MiRNAs play a key role as modulators of the potent profibrotic cytokine transforming growth factor (TGF)-beta, which is up-regulated in CD intestinal strictures. Here, we aimed to define mucosal miRNA expression profiles in strictured vs non-strictured CD and to explore the functional characteristics of miRNAs with differential expression.
Intestinal surgical specimens were collected from 17 patients with fibrostenosing CD, and total RNA was extracted from uninflamed ileal mucosa. MiRNA expression profiling was performed using Illumina v2.0 microRNA array comparing matched strictured to non-strictured areas from the same patient within each experimental group. Subsequent validation of differentially expressed miRNAs was performed using qRT-PCR. Overexpression of specific miRNAs was induced by transfection in myofibroblasts isolated from strictured CD mucosa, and changes in collagen mRNA expression and protein levels were detected by RT-qPCR and immunofluorescence, respectively. The in vitro effect of TGF-beta on miRNA expression by CD myofibroblasts was assessed by qRT-PCR.
We detected 12 miRNAs significantly up-regulated and 10 miRNAs significantly down-regulated (all p < 0.02) in strictured compared to non-strictured CD mucosa. Validation experiments confirmed the changes in miRNA expression detected by the microarray. Among differentially expressed miRNAs, we selected miR-34a (up-regulated in CD strictures) and miR-29b (down-regulated in CD strictures) and we studied their functional consequences. Induced expression of miR-29b resulted in a decrease of collagen III mRNA and protein levels, whereas miR-34a overexpression did not induce any significant changes. TGF-beta stimulation significantly down-regulated miR-29b expression by CD myofibroblasts.
Our findings show differential miRNA expression profiles in strictured versus non-strictured areas from CD patients. Collagen down-regulation suggests that miR-29b plays a functional role in modulating fibrosis in CD. Modulation of miRNA profiles may be a novel therapeutic strategy against fibrosis in CD.