No abstract

NCT00851565.

The first ECCO pathogenesis workshop focused on anti-TNF therapy failures in inflammatory bowel diseases (IBDs). The overall objective was to better understand and explore primary non response and loss of response to anti-TNF agents in IBD. The outcome of this workshop is presented into two parts. This first section addresses definitions, frequency and pharmacological aspects of anti-TNF therapy failure, including pharmacokinetics of anti-TNF monoclonal antibodies and immune and non-immune mediated clearance of anti-TNF mAbs. The second section concerns the biological roles of TNF and TNF antagonists, including mechanisms of action of anti-TNF agents, and discuss hypothesis regarding their failures and phenomenon of paradoxical inflammation, including the potential role of TNF independent inflammatory pathways.

Background: Fistulae are a troublesome complication of Crohn's disease but little is known of the final effector molecules responsible for matrix degradation. Although matrix metalloproteinases (MMPs) have been strongly implicated in tissue injury in Crohn's disease, their role in fistula formation is unknown. Aim: To determine the expression pattern of MMPs and tissue inhibitors of metalloproteinases (TIMPs) in fistulae of patients with Crohn's disease. Patients and methods: Resected fistula specimens were obtained from patients with Crohn's disease (n = 11) and classified according to the predominant histological features-that is, acute versus chronic inflammation. Patients with fistulae due to other diseases (n = 9) and normal colon (n = 5) served as controls. MMP and TIMP protein expression was measured by single or double labelled immunohistochemistry, and mRNA expression by in situ hybridisation. MMP activity was measured by gelatin zymography. Results: Compared with normal colon, strong MMP-3 expression was consistently observed in fistulae in Crohn's disease, irrespective of the stage of inflammatory activity. MMP-3 transcripts and protein were localised in large mononuclear cells and fibroblasts. MMP-9 transcripts and protein were expressed in granulocytes and only in fistulae with acute inflammation. Staining for MMP-1 and MMP-7 was weak and negative for MMP-10, whereas MMP-2 was equally expressed in normal colon and fistulae. TIMP-1, TIMP-2, and TIMP-3 expression was low in all samples. Similar expression patterns were found in fistulae of the disease control group. Fistulae also expressed active MMP-2 and MMP-9, as measured by gelatin zymography. Conclusion: MMP-3 and MMP-9 are markedly upregulated in intestinal fistulae and may contribute to fistula formation through degradation of the extracellular matrix, irrespective of the underlying disease process.

Background: Anti-tumour necrosis factor α (TNF-α) antibodies are effective in Crohn's disease and perhaps ulcerative colitis but antigenicity and the high cost have raised interest in other strategies to block TNF-α. These include the TNF-α converting enzyme (TACE) which releases soluble TNF-α from transmembrane pro-TNF-α. Aim: To investigate whether TACE activity is present in human colonic mucosa. Materials and methods: Detergent extracts of cell membranes from colonic biopsies were obtained from 12 controls and 28 patients with inflammatory bowel disease. Enzyme activity was measured by hydrolysis assays using pro-TNF-α or oligopeptide substrates spanning the known pro-TNF-α cleavage site at Ala(76)-Val(77). Cleavage products were identified by western blotting, high pressure liquid chromatography, or mass spectrometry. TACE protein was localised by immunohistochemistry and identified by western blotting of detergent extracts from purified lamina propria mononuclear cells (LPMNC) or epithelial cells. Results: Detergent extracts released TNF-α from pro-TNF-α and cleaved a model oligopeptide as predicted. Substrate hydrolysis was sensitive to known TACE/matrix metalloproteinase (MMP) inhibitors, but not trocade which has low activity against TACE. The median TACE level was increased in active ulcerative colitis (147 arbitrary units (AU)/mg; p<0.01) but not in Crohn's disease (81 AU/mg) compared with controls (79 AU/mg). Both the full length proform and the active form of TACE protein were expressed in LPMNC cells and epithelial cells. Conclusions: Functional TACE activity is ubiquitously expressed in the human colon and increased in ulcerative colitis, raising interest in MMP inhibitors targeting TACE.