PAR1 antagonism protects against experimental liver fibrosis. Role of proteinase receptors in stellate cell activation.
In fibroblasts, thrombin induces collagen deposition through activation of a G-protein-coupled receptor, proteinase-activated receptor 1 (PAR(1)). In the current study, we examined whether PAR(1) antagonism inhibits hepatic stellate cell (HSC) activation in vitro and whether it protects against fibrosis development in a rodent model of cirrhosis. A rat HSC line was used for in vitro studies whereas cirrhosis was induced by bile duct ligation (BDL). The current results demonstrated that HSCs express PAR(1), as well as proteinase-activated receptors 2 (PAR(2)) and 4 (PAR(4)), and that all three PARs were up-regulated in response to exposure to growth factor in vitro. Exposure to thrombin and to SFLLRN-(SF)-NH(2), a PAR(1) agonist, and GYPGKF (GY)-NH(2), a PAR(4) agonist, triggered HSC proliferation and contraction, as well as monocyte chemotactic protein-1 (MCP-1) production and collagen I synthesis and release. These effects were inhibited by the PAR(1) antagonist. Administration of this antagonist, 1.5 mg/kg/d, to BDL rats reduced liver type I collagen messenger RNA (mRNA) expression and surface collagen by 63%, as measured by quantitative morphometric analysis. Similarly, hepatic and urinary excretion of hydroxyproline was reduced significantly by the PAR(1) antagonist. In conclusion, PAR(s) regulates HSC activity; development of PAR antagonists might be a feasible therapeutic strategy for protecting against fibrosis in patients with chronic liver diseases.
Fiorucci
Stefano
S
Dipartimento di Medicina Clinica, Patologia, Clinica di Gastroenterologia ed Endoscopia Digestiva, University of Perugia, Perugia. fiorucci@unipg.it
Antonelli
Elisabetta
E
Distrutti
Eleonora
E
Severino
Beatrice
B
Fiorentina
Roviezzo
R
Baldoni
Monia
M
Caliendo
Giuseppe
G
Santagada
Vincenzo
V
Morelli
Antonio
A
Cirino
Giuseppe
G
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001652:Bile Ducts; D002461:Cell Line, Transformed; D024042:Collagen Type I / Q000096:biosynthesis; D051380:GRB2 Adaptor Protein; D015870:Gene Expression; D006490:Hemostatics / Q000494:pharmacology*; D008026:Ligation; D008099:Liver / Q000166:cytology; D008103:Liver Cirrhosis / Q000188:drug therapy* / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D044463:Receptor, PAR-1 / Q000235:genetics; D044464:Receptor, PAR-2 / Q000235:genetics; D018179:Receptors, Thrombin / Q000235:genetics; D013917:Thrombin / Q000494:pharmacology*; D010975:Platelet Aggregation Inhibitors
D048868:Adaptor Proteins, Signal Transducing; D024042:Collagen Type I; D051380:GRB2 Adaptor Protein; C482002:GYPGKF-NH(2); C495950:Grb2 protein, rat; D006490:Hemostatics; D009842:Oligopeptides; D010446:Peptide Fragments; D011506:Proteins; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin; C082835:thrombin receptor peptide (42-47); D020928:Mitogen-Activated Protein Kinases; D013917:Thrombin; C112908:protease-activated receptor 4; D010975:Platelet Aggregation Inhibitors