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P101. Analysis of the protease MT1-MMP and its substrates as biomarkers in IBD

A. Koziol1, Á. Pollán1, P. Gonzalo1, N. Núñez-Andrade1, P.M. Linares2, M.E. Fernández-Contreras2, M. Chaparro2, A.C. Urzainqui-Mayayo3, F. Sánchez-Madrid3, J.P. Gisbert2, A.G. Arroyo1, 1Centro Nacional de Investigaciones Cardiovasculares (CNIC), Vascular Biology and Inflammation, Madrid, Spain, 2Hospital Universitario de la Princesa-IP, Gastroenterology and CIBEREHD, Madrid, Spain, 3Hospital Universitario de la Princesa-IP, Immunology, Madrid, Spain

Background

We have recently reported that the protease MT1-MMP is up-regulated in TNFα-activated endothelial cells, where it can process substrates normally bound to the extracellular matrix, such as thrombospondin1 (TSP1) and nidogen1 (NID1), inducing their release and thus modulating the angiogenic response. Our aim was to analyse the expression of MT1-MMP and its substrates TSP1 and NID1 as potential biomarkers of inflammatory bowel disease (IBD), a chronic disorder involving inflammation and angiogenesis, in mouse models and human samples.

Methods

A mouse model of dextran sodium sulphate (DSS)-induced colitis was used. Immunostaining (IS) in colon sections was performed to analyse: (i) the angiogenic response with the specific endothelial cell marker CD31/PECAM1 and (ii) the expression of MT1-MMP, TSP1 and NID1, in control mice, mice treated with 1%DSS (moderate colitis) or 4%DSS (severe colitis). Also, TSP1, NID1 and VEGF levels were measured by ELISA in serum from patients with active ulcerative colitis (UC) or Crohn's disease (CD). MT1-MMP, TSP1 and NID1 expression was studied as well by IS of colon sections from controls or patients with CD.

Results

Increased presence of new vessels (CD31/PECAM1+) was observed in the lamina propria (LP) of mice with moderate colitis when compared to either control or mice with severe colitis. MT1-MMP, TSP1 and NID1 general pattern of expression changes along progression of mouse disease. In IBD patients, TSP1 and NID1 serum levels were significantly higher in UC and CD patients with low disease activity compared to high activity. MT1-MMP, TSP1 and NID1 expression pattern was also different in sections from CD patients compared to controls. IS with CD31/PECAM1 is currently being performed in these human samples to directly assess MT1-MMP expression and TSP1 and NID1 deposition by active endothelial cells.

Conclusion

Vascularization is higher in moderate vs severe colitis in the mouse model. This might correlate with increased expression of MT1-MMP in the LP and changes in the distribution of its substrates TSP1 and NID1 in 1%DSS-treated mice. Thus, serum levels of TSP1 and NID1 (indicative of their processing from the matrix) are significantly elevated in patients with low active UC and CD when compared with highly active disease. Double-IS studies with endothelial cell markers and quantification of soluble levels of TSP1 and NID1 in the mouse will further support the potential use of TSP1 and NID1 as biomarkers for diagnosis of pre-symptomatic low active IBD.