P056 Crohn’s Disease associated fibrosis modulates the expression of collagen receptors

Abstract

Abstract Background Crohn’s Disease (CD) patients often develop stenotic complications as immunomodulatory treatments do not prevent the fibrogenic response in the affected tissues, where a dysregulated activation of stromal cells provokes an excessive deposition of extracellular matrix (ECM). Recent evidences support the notion that local cells can sense the consequent alterations in tissue structure and rigidity through receptors that respond to some ECM components, and this may perpetuate the fibrogenic process even in the absence of inflammation. We aim to analyse the relevance of these signalling pathways in the fibrotic process associated to CD. Methods We obtained fibrotic ileal tissues from CD patients and healthy ileal samples from colon carcinoma patients (control), and analysed the expression (RT-PCR, IHQ) of collagen receptors (integrins, discoidin domain receptors/DDR) and of markers for some stromal cells (fibroblasts, endothelial cells). The relationship between these sets of data was analysed by Pearson’s correlation and the results organized as a correlation matrix. The expression of collagen receptors was also analysed in endothelial cells (HUVEC) treated with TGFβ 2 (1ng/ml, 48h). Results Ileal samples from CD patients present a differential gene expression of collagen receptors (Fig 1), with increased levels of ITGA10, ITGA11 and DDR2, and reduced expression of DDR1. In CD tissues, the expression of ITGA11 and DDR1 showed a significant correlation, positive and negative respectively, with that of endothelial markers (Fig 2). These correlations do not occur in control tissues. Integrin-α11 was detected in endothelial cells of submucosal vessels (IHQ). In HUVEC, TGFβ 2 increased the expression of ITGA11 (8.1±0.7 fold induction, p<0.01) and reduced that of DDR1 (0.74±0.06 fold induction, p<0.01), without affecting that of the other collagen receptors. Conclusion Intestinal tissues from CD patients affected by fibrosis present an altered pattern of expression of collagen receptors, which suggests a regulatory role of the ECM in the fibrotic response, while the correlation analysis and the changes induced by the fibrotic cytokine TGFβ in endothelial cells insinuates a particular relevance of these stromal cells in this process.