Expression and localisation of matrix metalloproteinases and their natural inhibitors in fistulae of patients with Crohn's disease.
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.


OBJECTIVE
To determine the expression pattern of MMPs and tissue inhibitors of metalloproteinases (TIMPs) in fistulae of patients with Crohn's disease.


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.


CONCLUSIONS
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.
Kirkegaard
T
T
Department of Medical Gastroenterology C, Herlev Hospital, University of Copenhagen, Denmark.
Hansen
A
A
Bruun
E
E
Brynskov
J
J
D000293:Adolescent; D000328:Adult; D003106:Colon / Q000201:enzymology / Q000378:metabolism; D003424:Crohn Disease / Q000150:complications / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D007412:Intestinal Fistula / Q000201:enzymology / Q000209:etiology / Q000378:metabolism*; D008297:Male; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism*
D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D020782:Matrix Metalloproteinases; D019278:Matrix Metalloproteinase 3; D020780:Matrix Metalloproteinase 9