Mast cells regulate intestinal barrier function during disease and homeostasis. Homeostatic regulation in vivo is through secretion of the mast cell-specific serine protease chymase. In the present study, we employ in vitro model systems to delineate the molecular pathways involved in chymase-mediated intestinal epithelial barrier dysfunction. Chymase stimulation of intestinal epithelial cell monolayers (Caco2bbe) induced a significant reduction in transepithelial resistance indicating decreased intestinal epithelial barrier function. The chymase-induced intestinal epithelial barrier dysfunction was characterized by chymase-induced protease-activated receptor-2 (PAR-2) activation and matrix metalloproteinase (MMP)-2 expression and activation. Consistent with this observation, in vitro analysis revealed chymase induced PAR-2 activation, and increased MAPK activity and MMP-2 expression. Pharmacological and siRNA-mediated antagonism of PAR-2 and MMP-2 significantly attenuated chymase-stimulated barrier dysfunction. Additionally, the chymase/MMP-2-mediated intestinal epithelial dysfunction was associated with a significant reduction in the tight junction protein claudin-5, which was partially restored by MMP-2 inhibition. Finally, incubation of Caco2bbe cells with chymase-sufficient, but not with chymase-deficient bone marrow-derived mast cells (BMMCs) decreased barrier function, which was attenuated by the chymase inhibitor, chymostatin. Collectively, these results suggest that mast cell/chymase-mediated intestinal epithelial barrier function is mediated by PAR-2/MMP-2-dependent pathways.
- mast cells
- epithelial permeability
- tight junctions
- Copyright © 2012, American Journal of Physiology- Gastrointestinal and Liver Physiology