Chronological expression of PAR isoforms in acute liver injury and its amelioration by PAR2 blockade in a rat model of sepsis

Summary

The liver can be injured and its functions altered by activation of the coagulation and inflammatory processes in sepsis. The objective of the present study was to investigate the pattern of protease-activated receptors (PARs) over time in a model of acute liver injury induced by lipopolysaccharide (LPS); and whether PARs playa role in this process and exert their effects through inflammation and coagulation. Levels of tumor necrosis factor-α (TNF-α) were significantly expressed 1 h after LPS administration followed by: i) an increase in levels of tissue factor, factor VIIa, thrombin and plasminogen activator inhibitor-1; ii) unchanged or steady levels of tissue factor pathway inhibitor; and iii) subsequent deposition of fibrin in the liver tissue, that led to the elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), which are associated with liver injury. The expression of all PAR isoforms (1–4) was elevated, and each isoform had a distinct cellular localization (hepatocytes, Kupffer cells, the portal triad area, and central veins) and a time-dependent pattern of expression. The immuno-reactivity of PAR2 and 4 in Kupffer cells was intense. Interestingly, PAR2 blocking peptide improved the healing of liver injuries, an effect that was associated with suppression of TNF-α elevation, and normalization of coagulation and fibrinolysis. This ultimately led to decreased fibrin formation in the injured liver. The present study reveals a distinct chronological expression and cellular localization of PARs in LPS-mediated liver injury and shows that blockade of PAR2 may playa crucial role in treating liver injury, via normalization of inflammation, coagulation and fibrinolytic pathways.

Key words

Coagulation - endotoxin - inflammation - liver injury - protease-activated receptor (PAR)

• References

• 1 Dhainaut JF, Marin N, Mignon A. et al. Hepatic response to sepsis: interaction between coagulation and inflammatory processes. Crit Care Med 2001; 29 Suppl S42-S7.
• 2 Pastor CM, Billiar TR, Losser MR. et al. Liver injury during sepsis. J Crit Care 1995; 10: 183-97.
• 3 Su GL. Lipopolysaccharides in liver injury: molecular mechanisms of Kupffer cell activation. Am J Physiol Gastrointest Liver Physiol 2002; 283: G256-G65.
• 4 Luster MI, Germolec DR, Yoshida T. et al. Endotoxin-induced cytokine gene expression and excretion in the liver. Hepatology 1994; 19: 480-8.
• 5 Hewett JA, Jean PA, Kunkel SL. et al. Relationship between tumor necrosis factor-α and neutrophils in endotoxin-induced liver injury. Am J Physiol Gastrointest Liver Physiol 1993; 265: G1011-G5.
• 6 Doi F, Goya T, Torisu M. Potential role of hepatic macrophages in neutrophil-mediated liver injury in rats with sepsis. Hepatology 1993; 17: 1086-94.
• 7 Shibayama Y. Sinusoidal circulatory disturbance by microthrombosis as a cause of endotoxin-induced hepatic injury. J Pathol 1987; 151: 315-21.
• 8 Todoroki H, Nakamura S, Higure A. et al. Neutrophils express tissue factor in a monkey model of sepsis. Surgery 2000; 127: 209-16.
• 9 Mochida S, Arai M, Ohno A. et al. Deranged blood coagulation equilibrium as factor of massive liver necrosis following endotoxin administration in partially hepatectomized rats. Hepatology 1999; 29: 1532-40.
• 10 Quax PA, van den Hoogen CM, Verheijen JH. et al. Endotoxin induction of plasminogen activator and plasminogen activator inhibitor type 1 mRNA in rat tissue in vivo . J Biol Chem 1990; 26: 15560-3.
• 11 Fearns C, Loskutoff DJ. Induction of plasminogen activator inhibitor1 gene expression in murine liver by lipopolysaccharide. Cellular localization and role of endogenous tumor necrosis factor-α. Am J Pathol 1997; 150: 579-90.
• 12 Yamashita M, Yamashita M. Tumor necrosis factor alpha is involved in the induction of plasminogen activator inhibitor-1 by endotoxin. Thromb Res 1997; 87: 165-70.
• 13 Esmon CT. Inflammation and thrombosis. J Thromb Haemost 2003; 01: 1343-8.
• 14 Coughlin SR. Thrombin signaling and protease-activated receptors. Nature 2000; 407: 258-64.
• 15 Dugina TN, Kiseleva EV, Chistov IV. et al. Receptors of the PARs family asa link between blood coagulation and inflammation. Biochemistry (Moscow) 2002; 67: 65-74.
• 16 Camerer E, Huang W, Coughlin SR. Tissue factorand factor X-dependent activation of protease-activated receptor 2 by factor VIIa. PNAS 2000; 97: 5255-60.
• 17 Riewald M, Ruf W. Orchestration of coagulation protease signaling by tissue factor. Trend Cardiovascular Med 2002; 12: 149-54.
• 18 Copple BL, Moulin F, Hanumegowda UM. et al. Thrombin and protease-activated receptor-1 agonists promote lipopolysaccharide-induced hepatocellular injury in perfused livers. J Pharmacol Exp Ther 2003; 305: 417-25.
• 19 Nystedt S, Ramakrishnan V, Sundelin J. The proteinase-activated receptor 2 is induced by inflammatory mediators in human endothelial cells. J Biol Chem 1996; 271: 14910-5.
• 20 Hamilton JR, Frauman AG, Cocks TM. Increased expression of protease-activated receptor-2 (PAR2) and PAR4 in human coronary artery by inflammatory stimuli unveils endothelium-dependent relaxations to PAR2 and PAR4 agonists. Circ Res 2001; 89: 92-8.
• 21 Jesmin S, Gando S, Matsuda N. et al. Temporal changes in pulmonary expression of key coagulant molecules in rabbits with endotoxin-induced acute lung injury: elevated expression levels of protease-activated receptors. Thromb Haemost 2004; 92: 966-79.
• 22 Jesmin S, Sakuma I, Salah-Eldin A. et al. Diminished penile expression of vascular endothelial growth factor and its receptors at the insulin-resistant stage of a type II diabetic rat model:a possible cause for erectile dysfunction in diabetes. J Mol Endocrinol 2003; 31: 401-18.
• 23 Maeda S, Miyauchi T, Iemitsu M. et al. Effects of exercise training on expression of endothelin-1 mRNA in the aorta of aged rats. Clin Sci (Lond) 2002; (Suppl. 48) 118S-23S.
• 24 Levi M, de Jonge E, van der Poll T. Sepsis and disseminated intravascular coagulation. J Thromb Thrombolysis 2003; 16: 43-7.
• 25 Pearson JM, Schultze AE, Schwartz KA. et al. The thrombin inhibitor, hirudin, attenuates lipopolysaccharide-induced liver injury in the rat. J Pharmacol Exp Ther 1996; 278: 378-83.
• 26 Vergnolle N. Proteinase-activated receptor-2 activating peptides induce leucocyte rolling, adhesion, and extravasation in vivo. J Immunol 1999; 163: 5064-9.
• 27 Blackhart BD, Emilsson K, Nguyen D. et al. Ligand cross-reactivity within the protease-activated receptor family. J Biol Chem 1996; 271: 16466-71.
• 28 Pawlinski R, Pedersen B, Schabbauer G. et al. Role of tissue factor and protease-activated receptors in a mouse model of endotoxemia. Blood 2004; 103: 1342-7.
• 29 Katakaoka H, Hamilton JR, McKemy DD. et al. Protease-activated receptors 1 and 4 mediate thrombin signaling in endothelial cells. Blood 2003; 102: 3224-31.