Transforming growth factor beta signalling and matrix metalloproteinases in the mucosa overlying Crohn's disease strictures

Di Sabatino, A., Jackson, C.L., Pickard, K.M., Buckley, M., Rovedatti, L., Leakey, N.A., Picariello, L., Cazzola, P., Monteleone, G., MacDonald, T.T. and Pender, S.L.F. (2009) Transforming growth factor beta signalling and matrix metalloproteinases in the mucosa overlying Crohn's disease strictures. Gut, 58 (6), 777-789. (doi:10.1136/gut.2008.149096).

Abstract

Background and Aims: in addition to its crucial role in dampening tissue-damaging immune responses in the gut, transforming growth factor b (TGFb) is a potent profibrogenic agent inducing collagen synthesis and regulating the balance between matrix-degrading matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). TGFb signalling was investigated by analysis of Smad proteins and MMPs/TIMPs in the mucosa overlying strictures in patients with Crohn’s disease (CD).
Methods: specimens were collected from macroscopically normal mucosa overlying strictured and nonstrictured gut of patients with fibrostenosing CD. Isolated myofibroblasts were cultured with anti-TGFb blocking antibody or TGFb1. TGFb transcripts were analysed by quantitative reverse transcription-PCR (RT-PCR). Smad proteins and MMPs were determined by immunoblotting. MMP-12 activity was measured by a real-time MMP-12 activity assay. An in vitro wound-healing scratch assay was used to assess myofibroblast migration.
Results: TGFb transcripts, phosphorylated Smad2– Smad3 (pSmad2–3) and TIMP-1 proteins were higher in mucosa overlying strictures than in mucosa overlying nonstrictured areas. In contrast, mucosa overlying strictured gut had lower expression of Smad7, MMP-12 and MMP- 3. Myofibroblasts from mucosa overlying strictured gut showed higher TGFb transcripts, a greater pSmad2–3 response to TGFb, increased TIMP-1, lower Smad7, increased collagen production and reduced migration ability compared with myofibroblasts from mucosa overlying non-strictured gut. TGFb blockade increased myofibroblast MMP-12 production and migration, more obviously in myofibroblasts isolated from mucosa overlying non-strictured compared with strictured gut.
Conclusions: changes in TGF-b signalling and MMP production were identified in the mucosa overlying strictures in CD which may give a window into the process of fibrosis

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Contributors

Author: S.L.F. Pender

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