The defective intestinal tight junction (TJ) barrier has a key pathogenic factor in Crohn’s disease (CD) and other inflammatory conditions of the gut. Clinical studies in CD patients have shown that a persistent increase in intestinal permeability is predictive of poor clinical outcome. Matrix metalloproteinase-9 (MMP-9) has been shown to be markedly increased in intestinal tissues of patients with CD and it has been postulated that MMP-9 plays an important role on the pathogenesis of intestinal inflammation in CD.