Mo1714 Analysis of the Protease MT1-MMP As Therapeutic Target in IBD

Abstract

Background: We have recently demonstrate higher levels of the MT1-MMP by qPCR -in biopsiesand higher levels of its substrates thrombospondin-1 (TSP1) and nidogen-1 (NID1) -in serumfrom patients of inflammatory bowel disease (IBD), a chronic disorder involving inflammation and angiogenesis. Our objective was analysing the functional role of MT1MMP in the angiogenesis and damage produced in IBD. Methods: Gene expression of MT1MMP was detected by qPCR in biopsies, and TNFα, VEGFA, TSP1, NID1 levels were quantified by ELISA in serum from patients with active ulcerative colitis (UC) or Crohn's disease (CD). Clinical IBD activity was assessed respectively by the Mayo score for UC, and by the Harvey-Bradshaw index for CD. Endoscopic activity was determined with the Mayo subscore and the SES-CD index. MT1-MMP, TSP1 and NID1 expression and the angiogenic response were also analyzed by immunostaining (IF) in colonic sections from controls or patients affected by IBD. Besides, we used a mouse model of dextran sulphate sodium (DSS)induced colitis to analysed the angiogenic response by IF with the specific endothelial cell markers CD31, VE cadherin, and the expression of MT1-MMP, and its substrates TSP1 and NID1 by IF of histological colon sections from either control mice or mice treated with 1% DSS (moderate colitis) or 4% DSS (severe colitis), in wild type mice. The endothelial MT1MMP expression was also analysed in MT1-MMPLacZ/+ mice. Finally, the in vivo functional analysis was done in mice with endothelium-specific deletion of MT1-MMP generated by (MT1-MMPflox/floxxVECadhERT2-Cre) breeding analyzing: (i) colitis score; (ii) vascular pattern quantifying, perfusion, endothelial proliferation and colonic hypoxia (injection and stainings of isolectinB4, EdU, and Pimonidazole); and (iii) inflammatory infiltrate (IF with CD11b). Results: MT1-MMP expression was higher in biopsies of patients with active IBD, moreover, serum levels of TSP-1 and NID1 were significantly increased in UC and CD patients with low activity. In the mouse colitis model, serum levels of TNFα, VEGF-A, TSP1 y NID1 and MT1-MMP expression in intestinal tissues, were increased along the progression of the mouse disease, as well as the angiogenesis in the intestinal mucosa. Our preliminary results indicate that the absence of MT1-MMP in EC protects from IBD, through a vascular normalization (reestablishment of structure and function of blood vessels), with the consequent decrease of colonic hypoxia and inflammation. Conclusions: These data support the potential use of TSP1 and NID1 as biomarkers in the diagnostic of pre-symptomatic or low activity IBD, aiming the endothelial MT1-MMP as a new therapeutic target for normalization of vasculature and improve the symptoms in IBD.