Proinflammatory role of protease-activated receptor-2 in intestinal ischemia/reperfusion injury in rats

Protease-activated receptors (PARs) are widely recognized for their modulatory properties during inflammation. The aim of the present study was to examine the role of PAR-2 on ischemia/reperfusion-induced small intestinal injury in rats. Intestinal damage was induced in male Wistar rats by clamping both the superior mesenteric artery and the celiac trunk for 30 min, followed by reperfusion for 60 min. Expression of PAR-2 in the intestinal mucosa was estimated by Western blot analysis and real-time PCR. Anti-rat PAR-2 cleavage site (PCS) antibody was intraperitoneally administered to the rats 1 h before the vascular clamping. The intestinal mucosal injury and inflammation were evaluated by biochemical markers and histological findings. Thiobarbituric acid (TBA) reactive substances and tissue-associated myeloperoxidase (MPO) activity were measured in the intestinal mucosa as indices of lipid peroxidation and neutrophil infiltration, respectively. Expression of cytokine-induced neutrophil chemoattractant-1 (CINC-1) in intestinal mucosa was measured by enzyme-linked immunosorbent assay. Expression of PAR-2 mRNA and protein in the intestinal mucosa was increased after reperfusion following ischemia. Reperfusion after ischemia resulted in an increase in luminal protein concentrations, hemoglobin concentrations, TBA reactive substances, MPO activity and CINC-1 protein. Pre-treatment with anti-rat PCS antibody significantly inhibited the increases in these parameters. These results suggest that PAR-2 plays an important role in the pathogenesis of ischemia/reperfusion-induced intestinal injury.