Serine Protease Inhibition Reduces Post-Ischemic Granulocyte Recruitment in Mouse Intestine

Abstract

Proteases and proteinase-activated receptor (PAR) activation are involved in several intestinal inflammatory conditions. We hypothesized that serine proteases and PAR activation could also modulate the intestinal injury induced by ischemia-reperfusion (I-R). C57Bl/6 mice were subjected to 90 minutes of intestinal ischemia followed or not by reperfusion. Sham-operated animals served as controls. After ischemia, plasma and tissue serine protease activity levels were increased compared to the activity measured in plasma and tissues from sham-operated mice. This increase was maintained or further enhanced after 2 and 5 hours of reperfusion, respectively. Trypsin (25 kDa) was detected in tissues both after ischemia and 2 hours of reperfusion. Treatment with FUT-175 (10 mg/kg), a potent serine protease inhibitor, increased survival after I-R, inhibited tissue protease activity, and significantly decreased intestinal myeloperoxidase (MPO) activity and chemokine and adhesion molecule expression. We investigated whether serine proteases modulate granulocyte recruitment by a PAR-dependent mechanism. MPO levels and adhesion molecule expression were significantly reduced in I-R groups pre-treated with the PAR(1) antagonist SCH-79797 (5 mg/kg) and in Par(2)(-/-)mice, compared, respectively, to vehicle-treated group and wild-type littermates. Thus, increased proteolytic activity and PAR activation play a pathogenic role in intestinal I-R injury. Inhibition of PAR-activating serine proteases could be beneficial to reduce post-ischemic intestinal inflammation.

Protectin D1 n-3 DPA and resolvin D5 n-3 DPA are effectors of intestinal protection

“…In anesthetized mice, the superior mesenteric artery (SMA) was occluded for 50 min; on reperfusion, PD1 n-3 DPA , RvD5 n-3 DPA , or vehicle was given, and tissues collected at 5 h. MPO activity was measured as an index of neutrophil infiltration (39). Tissue sections (5 μm) were stained with H&E. Microscopic histological damage score was evaluated blindly (40).…”

“…Samples harvested for histology were analyzed by light microscopy and scored (37,38). MPO activity was performed as previously described (39). Intestinal levels of cytokines were assayed using ELISA kit.…”

Changes in Bowel Microbiota Induced by Feeding Weanlings Resistant Starch Stimulate Transcriptomic and Physiological Responses

“…Serine proteases have an important role in the induction of inflammation at mucosal surfaces (16,22) and defense against infection (13). Inhibition of serine protease has been shown to reduce inflammation and tissue damage (11,14,44). However, serine proteases are also able to promote the generation of immune-suppressing CD4 ϩ FOXP3 ϩ regulatory T cells in vitro (34).…”

Autodigestion

“…The escape of pancreatic proteases from the small intestine is accompanied by an increase in digestive protease activity in plasma and tissues, such as the liver, lung and heart (25,27), suggesting that endogenous inhibitors of digestive proteases may become fully bound and their ability to block proteases has become saturated (28–30). In experimental shock, proteases circulate in plasma and exhibit elevated activities as detected by cleavage of fluorescently quenched substrates (27,31), irrespective of whether caused by a directly ischemic state (e.g. hemorrhagic shock, splanchnic artery occlusion), by exposure to endotoxin or digested food in the intestine (e.g.…”