A farnesoid x receptor-small heterodimer partner regulatory cascade modulates tissue metalloproteinase inhibitor-1 and matrix metalloprotease expression in hepatic stellate cells and promotes resolution of liver fibrosis.
The farnesoid X receptor (FXR) is expressed by and regulates hepatic stellate cells (HSCs). In the present study, we investigated whether 6-ethyl chenodeoxycholic acid (6-ECDCA or INT-747), a semisynthetic derivative of chenodeoxycholic acid (CDCA), modulates tissue metalloproteinase inhibitor (TIMP)-1 and matrix metalloprotease (MMP)-2 expression/activity in HSCs and in the liver of rats rendered cirrhotic by 4-week administration of CCl(4). Exposure of HSCs to FXR ligands increases small heterodimer partner (SHP) mRNA by 3-fold and reduces basal and thrombin-stimulated expression of alpha1(I)collagen, alpha-smooth muscle actin (alpha-SMA), TIMP-1, and TIMP-2 by approximately 60 to 70%, whereas it increased matrix metalloprotease (MMP)-2 activity by 2-fold. In coimmunoprecipitation, electromobility shift, and transactivation experiments, FXR activation/overexpression caused a SHP-dependent inhibition of JunD binding to its consensus element in the TIMP-1 promoter. Inhibition of TIMP-1 expression by SHP overexpression enhanced the sensitivity of HSCs to proapoptogenic stimuli. Administration of 3 mg/kg 6-ECDCA, but not 15 mg/kg ursodeoxycholic acid, resulted in early (3-5-day) induction of SHP and prevention of early up-regulation of TIMP-1 mRNA induced by CCl(4). In the prevention protocol, 4-week administration of 6-ECDCA reduced alpha1(I)collagen, alpha-SMA, and TIMP-1 mRNA by 60 to 80%, whereas it increased MMP-2 activity by 5-fold. In the resolution protocol, administration of 3 mg/kg 6-ECDCA promoted liver fibrosis resolution and increased the apoptosis of nonparenchyma liver cells. By demonstrating that a FXR-SHP regulatory cascade promotes the development of a quiescent phenotype and increases apoptosis of HSCs, this study establishes that FXR ligands may be beneficial in treatment of liver fibrosis.
Fiorucci
Stefano
S
Dept. of Clinical and Experimental Medicine, University of Perugia, Policlinico Monteluce, Via E. Dal Pozzo, 06122 Perugia, Italy. fiorucci@unipg.it
Rizzo
Giovanni
G
Antonelli
Elisabetta
E
Renga
Barbara
B
Mencarelli
Andrea
A
Riccardi
Luisa
L
Orlandi
Stefano
S
Pruzanski
Mark
M
Morelli
Antonio
A
Pellicciari
Roberto
R
D000199:Actins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D002252:Carbon Tetrachloride Poisoning / Q000473:pathology; D002469:Cell Separation; D004268:DNA-Binding Proteins / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000502:physiology*; D022781:Hepatocytes / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008103:Liver Cirrhosis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D020782:Matrix Metalloproteinases / Q000096:biosynthesis*; D010957:Plasmids / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000096:biosynthesis*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000502:physiology*; D000099150:Receptor, Farnesoid X-Activated
D000199:Actins; D004268:DNA-Binding Proteins; D020778:Matrix Metalloproteinase 2; D020782:Matrix Metalloproteinases; D016755:Proto-Oncogene Proteins c-jun; D018160:Receptors, Cytoplasmic and Nuclear; D019715:Tissue Inhibitor of Metalloproteinase-1; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D000099150:Receptor, Farnesoid X-Activated