Tissue proteolysis in appendicitis with perforation.

BACKGROUND: Matrix metalloproteinases (MMPs) and serine proteases are able to degrade the extracellular matrix (ECM) and modulate immune responses in the gastrointestinal tract. The purpose of this study was to investigate local proteolysis in perforated appendicitis and its association with the appendix perforation. MATERIALS AND METHODS: Biopsies were taken at the sites of perforation (n = 15) and with a gradually increased distance from it. The expression and distribution of MMP-1, -2, and -9, the tissue inhibitor of metalloproteinases type (TIMP-1), plasminogen activator inhibitor type1 (PAI-1), and urokinase plasminogen activator (uPA) were measured by ELISA. The distribution of MMP-9, TIMP-1, uPA, and PAI-1 in perforated, nonperforated, and uninflamed appendix was investigated by immunohistochemistry with monoclonal antibody technique. RESULTS: MMP-1 expression was highest close to the perforation and was gradually decreased in biopsies in more distal locations (P < 0.01). MMP-9 showed a similar pattern being highest at the sites of perforation (P < 0.05), while MMP-2 expression showed a trend in the opposite direction without statistically significance. The expression of TIMP-1 trended lower at the sites of perforation. PAI-1 was highest at the sites of perforation (P < 0.01) and the uPA expression was similarly elevated close to and at the perforation. CONCLUSIONS: These data indicate a key role of MMP in the pathogenesis of appendix perforation. A local imbalance between MMP-9 and the inhibitor TIMP-1 could potentially contribute to the tissue injury leading to an appendix perforation. The overexpression of PAI-1 at the sites of perforation may also contribute to tissue damage.

Progress of tissue injury in appendicitis involves the serine proteases uPA and PAI-1.

OBJECTIVE: Serine proteases and the matrix metalloproteinases (MMPs) are key factors in the proteolytic cascade and participate in extracellular matrix (ECM) degradation. Fibrinolytic activators and inhibitors may have an effect on inflammatory cells, thereby modulating the inflammatory response. It is reasonable to assume that they may be implicated in the tissue injury in acute appendicitis that subsequently leads to appendix perforation. The purpose of this study was to investigate the expression and distribution of urokinase-type plasminogen activator (uPA) and plasminogen-activator inhibitor type 1 (PAI-1) in appendicitis. MATERIAL AND METHODS: Expression of uPA and expression of PAI-1 were measured in tissue specimens from patients with appendicitis (n=30) and in control specimens (n=9), using the quantitative ELISA technique. Distribution of enzymes was studied with immunohistochemistry. The uPA and PAI-1 levels in the subgroups of appendicitis and controls were compared. RESULTS: The overall expressions of uPA and PAI-1 were greater in appendicitis than in control specimens (p <0.001 and p<0.0001, respectively). Expressions of uPA and PAI-1 in phlegmonous (n=15), gangrenous (n=6) and perforated appendicitis (n=9) were all higher than those in controls (n=9), (p<0.01). Moreover, the PAI-1 level was elevated in perforated appendicitis compared with phlegmonous appendicitis (p<0.01). uPA staining was observed in connection with vascular endothelial cells and the serosa stained intensely in specimens from perforated appendicitis. CONCLUSIONS: The expression of uPA and especially the over-expression of PAI-1 seem to correlate to the progression of local inflammatory response in acute appendicitis.

A local imbalance between MMP and TIMP may have an implication on the severity and course of appendicitis.

BACKGROUND: Matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs) have been demonstrated to be involved in inflammatory conditions in the intestine. The purpose of this study was to investigate whether the alterations of the MMP/TIMP balance might reflect the course of the inflammatory process in acute appendicitis and if the expression and localisation of MMPs and TIMP is variable in the various clinical manifestations of appendicitis. MATERIALS AND METHODS: The study comprises 40 patients (26 men and 14 women) having emergency appendectomy and a control group constituting of 10 patients (5 men and 5 women) having a hemicolectomy for other reasons. MMP and TIMP expressions were assessed and compared in tissue specimens from phlegmonous (n = 15), gangrenous (n = 7), perforated appendicitis (n = 11) and controls with noninflamed appendices (n = 10) by means of enzyme-linked immunosorbent assay technique. Localisation of the enzymes was performed by immunohistochemistry. RESULTS: MMP-1 was significantly higher in gangrenous and perforated appendicitis compared with phlegmonous appendicitis and controls (p < 0.05) while MMP-2 was significantly lower in gangrenous appendicitis compared with phlegmonous appendicitis and controls. MMP-2 was also lower in perforated appendicitis when compared with controls (p < 0.01). Elevated expression of MMP-9 was demonstrated in all groups of appendicitis compared with the controls (p < 0.001). CONCLUSIONS: MMP-9 is the most abundantly expressed MMP of those investigated in inflamed appendix. We postulate that a local imbalance between MMP-9 and TIMP-1 may trigger a perforation. These results suggest that MMPs might be useful as biomarkers of appendices prone to perforation.