Genetic Deletion of Tissue Inhibitor of Metalloproteinase-1/TIMP-1 Alters Inflammation and Attenuates Fibrosis in Dextran Sodium Sulphate-induced Murine Models of Colitis

Increased levels of tissue inhibitor of metalloproteinase-1 [TIMP-1] have been detected in both inflammatory and fibrotic lesions in Crohn's disease. In a murine model of chronic inflammation, fibrosis was associated with an increase in TIMP-1 and inhibition of matrix metalloproteinase [MMP]-mediated degradation. We investigated the effect of TIMP-1 deficiency in acute and chronic murine models of colitis. Colitis was induced via oral administration of dextran sodium sulphate [DSS] to B6.129S4-Timp1(tm1Pds)/J knock-out [KO] and C57BL/6J wild-type [WT] mice. Levels of inflammation and fibrosis were assessed and gelatin zymographies and gene expression microarrays were performed. Compared with WT mice, TIMP-1 KO mice had higher inflammatory parameters after acute DSS administration and developed less fibrosis after chronic DSS administration. MMP-2 levels were increased in WT versus TIMP-1 KO mice with acute colitis, whereas a trend for higher proMMP-9 levels was observed in WT versus TIMP-1 KO mice with chronic colitis. In control conditions, several immune-related genes [e.g Ido1, Cldn8] were differentially expressed between young TIMP-1 KO and WT mice, but to a lesser extent between older TIMP-1 KO and WT mice. In response to DSS, the gene expression pattern was significantly different between young TIMP-1 KO and WT mice, whereas it was similar in older TIMP-1 KO and WT mice. TIMP-1 deficiency leads to differential expression of immune-related genes and to attenuated development of fibrosis. Unravelling the role of TIMP-1 in intestinal remodelling is necessary to develop more effective and more targeted therapeutic strategies for intestinal fibrosis.