Search in the Abstract Database

Search Abstracts 2015

* = Presenting author

P002 Genetic deletion of tissue inhibitor of metalloproteinase-1/TIMP-1 attenuates DSS-induced inflammation and fibrosis in a mouse model of colitis.

M. de Bruyn*1, 2, C. Breynaert3, I. Arijs2, 4, J. Cremer3, L. Van Lommel4, K. Geboes5, G. De Hertogh5, M. Ferrante2, S. Vermeire2, G. Van Assche2, J. Ceuppens3, G. Opdenakker1

1Rega Institute for Medical Research - KU Leuven, Microbiology and Immunology, Leuven, Belgium, 2University Hospitals Leuven - KU Leuven, Translational Research Center for Gastrointestinal Disorders (TARGID), Leuven, Belgium, 3KU Leuven - Laboratory of Clinical Immunology, Department of Microbiology and Immunology, Leuven, Belgium, 4KU Leuven, Department of Cellular and Molecular Medicine, Gene Expression Unit, Leuven, Belgium, 5KU Leuven - Translational Cell and Tissue Research, Department of Imaging and Pathology, Leuven, Belgium

Background

Tissue remodeling and fibrosis are hallmarks of inflammatory bowel diseases (IBD). An increased level of tissue inhibitor of metalloproteinase-1 (TIMP-1) has been reported in fibrotic strictures in Crohn's disease (CD). The aim of this study was to investigate the effect of TIMP-1 deficiency in an acute and chronic mouse model of inflammatory colitis.

Methods

Colitis was induced in 8-10 week old female B6.129S4-Timp1tm1Pds/J knock-out (KO) mice and C57BL/6J control mice. Acute colitis was induced by oral administration of 3% dextran sodium sulphate (DSS) for 7 days followed by 2 days of regular water. Chronic colitis was induced by 3 cycles of 1 week of exposure to 1.75-2.0% DSS followed by a recovery phase of 2 weeks. Systemic inflammation, colonic inflammation and fibrosis were assessed by macroscopic parameters, histopathology analysis and tissue collagen levels. Gelatinase levels were determined with gelatin zymography and gene expression differences were assessed with Affymetrix Mouse Gene 1.0 ST arrays (false discovery rate < 5% and >2-fold).

Concordance of twin pairs classified by zygosity and disease type

Crohn’s DiseaseUlcerative Colitis
Monozygotic53.3%25%
Dizygotic10%19.4%

Results

In comparison with control mice, DSS administration to TIMP-1 KO mice resulted in significantly less weight loss (p<0.001 [acute] and p=0.006 [chronic]) and less systemic inflammation (p<0.001 [acute] and p=0.031 [chronic]). After chronic DSS administration, TIMP-1 KO mice had reduced colonic inflammation (macroscopic damage: p<0.001, histological inflammation: p=0.016) and lower tissue collagen levels compared to control mice (p=0.003). ProMMP-9 levels were higher in controls with chronic colitis (p=0.050), whereas proMMP-2 (p=0.002) and activated MMP-2 (p=0.040) levels were higher in controls with acute colitis compared to TIMP-1 KO mice. Comparison of gene expression levels after acute DSS administration showed that TIMP-1 KO mice had an upregulation of Ido1 (Fold change [FC]=15, p=0.010), Gal3st3 (FC=8.8, p=0.010), Xpnpep2 (FC=7.5, p=0.002) and downregulation of Mmp-2 (FC=3.3, p=0.020), Mmp-9 (FC=3.1, p=0.030), Cldn1 (FC=3, p=0.040) compared to control mice. Young TIMP-1 KO mice (10-12 weeks) versus older animals (19-21 weeks) showed significantly increased expression of Reg3g (FC=16, p=0.03), Reg3b (FC=12.6, p=0.040) and Ido1 (FC=3.5, p=0.008), whereas the expression levels of Mir200b (FC=2.2, p=0.009), Ctse (FC=1.3, p=0.030) and Wnt2b (FC=1.1, p=0.002) were decreased.

Conclusion

TIMP-1 deficiency leads to upregulation of anti-bacterial and innate immunity genes, resulting in an attenuated development of acute colitis. In a chronic setting of inflammation, TIMP-1 KO mice have less remodeling and fibrosis. Unraveling the role of TIMP-1 in extracellular matrix remodeling will be necessary to understand the biology of intestinal wound healing and fibrosis in IBD.