Protease-Activated Receptor 2 Blocking Peptide Counteracts Endotoxin-Induced Inflammation and Coagulation and Ameliorates Renal Fibrin Deposition in a Rat Model of Acute Renal Failure

Glomerular and microvascular thrombosis due to the activation of inflammation and coagulation pathway contribute to the occurrence of acute renal failure in sepsis. The protease-activated receptors (PARs) have been shown to play an important role in the interplay between inflammation and coagulation. We hypothesized that PAR-2 blocking would improve glomerular and vascular thrombosis by attenuating inflammation and coagulation, leading to the prevention of acute renal failure, and assessed the effects of the PAR-2 blocking peptide (PAR-2 BP) in a rat model of LPS-induced acute renal failure. Levels of TNF-alpha were significantly expressed 1 h after LPS administration, followed by 1) an increase in levels of tissue factor, factor VIIa, factor Xa, thrombin and plasminogen activator inhibitor 1; 2) unchanged levels of tissue factor pathway inhibitor; and 3) subsequent deposition of fibrin in kidney tissues, which led to the elevation of creatinine and blood urea nitrogen. Time-dependent PAR-2 expression was observed at both the gene and protein levels. Immunoreactivities of PAR-2 and fibrin were observed in the glomerulus and small arteries. Protease-activated receptor blocking peptide suppressed TNF-alpha elevation and attenuated activation of the coagulation, thus leading to a decrease in fibrin formation and its deposition in the glomerulus. However, the levels of creatinine and blood urea nitrogen remained unchanged. These results show that PAR-2 plays a key role in the inflammatory and coagulation process of LPS-induced renal failure; however, PAR-2 inhibition alone does not affect improvement in the renal function.