Imbalance of stromelysin-1 and TIMP-1 in the mucosal lesions of children with inflammatory bowel disease

Abstract

Background: Degradation of the extracellular matrix and ulceration of the mucosa are major features of inflammatory bowel disease (IBD). One of the most important enzymes in degrading the matrix and produced in excess by cytokine activated stromal cells, is stromelysin-1. The activity of stromelysin-1 is controlled by tissue inhibitor of metalloproteinase (TIMP-1), its natural inhibitor. In model systems excess stromelysin-1 produces mucosal degradation.

Methods: Quantitative competitive RT-PCR was used to analyse stromelysin-1 and TIMP-1 transcripts; western blotting was used to measure the amount of stromelysin-1 and TIMP-1 protein in biopsy samples from children with IBD.

Results: In biopsies from patients with active Crohn's disease (n=24), ulcerative colitis (n=23), and controls (n=16), TIMP-1 transcripts and protein were abundant and unchanged. Stromelysin-1 transcripts and protein were markedly elevated in mucosal biopsies obtained from inflamed sites of patients with active IBD but were not elevated in adjacent endoscopically normal mucosa (n=10). Elevated levels of stromelysin-1 transcripts in active Crohn's disease (n=5) returned to normal levels following treatment with enteral nutrition.

Conclusions: Stromelysin-1 is markedly overexpressed at inflamed sites in patients with IBD whereas TIMP-1 remains unaltered. Excess stromelysin-1 is likely to be responsible for loss of mucosal integrity in IBD.

Figures

Figure 1

Stromelysin-1 (A), TIMP-1 (B) mRNA, and their ratio (C) in active Crohn's disease and ulcerative colitis (UC), and in normal controls, as measured by quantitative reverse transcription-polymerase chain reaction (RT-PCR).

Figure 2

Quantitative analysis of stromelysin-1 protein (A), TIMP-1 protein (B), and their ratio (C) in active Crohn's disease and ulcerative colitis (UC), and in normal controls, as measured by densitometric scanning of western blots.

Figure 3

Western blot showing increased expression of stromelysin-1 in children with active Crohn's disease and ulcerative colitis (UC) compared with normal controls (60 and 58 kDa latent bands, with 56, 54, and 44 kDa active enzyme bands).

Figure 4

Stromelysin-1 mRNA in endoscopically normal and abnormal large bowel mucosa in children with IBD (Crohn's disease (•), ulcerative colitis (◯).

Figure 5

Stromelysin-1 mRNA before and after enteral nutrition in children with Crohn's disease.