Bile Acids and Liver Fibrosis Causative Agent and Therapeutic Tool

Bile Acids and Liver Fibrosis Causative Agent and Therapeutic Tool Peter Fickert, Andrea Fuchsbichler, Tarek Moustafa, Gernot Zollner, Emina Halilbasic, Ulrike Stöger, Cord Langner, Helmut Denk, and Michael Trauner Laboratory of Experimental and Molecular Hepatology, Departments of Medicine and Pathology, Medical University of Graz, Austria

Questions YOU are currently entertaining Are there different types of liver fibrosis? What are the current concepts of the biliary type of liver fibrosis? What have we learned from mouse models? How could bile acids be a therapeutic tool in liver fibrosis?

Questions YOU are currently entertaining Are there different types of liver fibrosis?

Normal Liver Modified Silver Stain

ASH Modified Silver Stain

ASH Sirius red

PSC Sirius red hv pv

pv PSC Sirius red hv

PSC Modified Silver Stain pv

Summary I: Fibrosis Patterns Yes, there are different patterns of liver fibrosis Related to kind of trigger? Related to activated cell type?

Questions YOU are currently entertaining What are the current concepts of biliary type of liver fibrosis?

Pathogenetic Concepts of Cholangiopathies and Biliary Fibrosis autocrine/paracrine stimulation Reactive Cholangiocytes TGF-β, MCP-1, Osteopontin PDGF,TNF-α NGFs VCAM, ICAM NO

Pathogenetic Concepts of Cholangiopathies and Biliary Fibrosis IL-4 IL-5 IL-8 INF-γ ICAM VCAM FasL CD8 CD4 autocrine/paracrine stimulation Reactive Cholangiocytes TGF-β, MCP-1, Osteopontin PDGF,TNF-α NGFs VCAM, ICAM NO PMNs Source of ROS?

Pathogenetic Concepts of Cholangiopathies and Biliary Fibrosis IL-4 IL-5 IL-8 INF-γ ICAM VCAM FasL CD8 CD4 autocrine/paracrine stimulation Reactive Cholangiocytes TGF-β, MCP-1, Osteopontin PDGF,TNF-α NGFs VCAM, ICAM NO Activated Myofibroblasts ECM production Wound healing? PMNs Source of ROS?

Pathogenetic Concepts of Cholangiopathies and Biliary Fibrosis TRIGGER? IL-4 IL-5 IL-8 INF-γ ICAM VCAM FasL CD8? CD4 autocrine/paracrine stimulation? Reactive Cholangiocytes TGF-β, MCP-1, Osteopontin PDGF,TNF-α NGFs VCAM, ICAM NO Activated Myofibroblasts ECM production Wound healing?? PMNs Source of ROS?

Do Bile Acids Activate Myofibroblasts (MFBs)? Isolation of MFBs from Mdr2 -/- Characterization of MFBs: Vimentin +, Desmin +, α-sma +, CK 19 - Treatment: Proinflammatory cytokines α-sma Bile Acids Parameters: BrdU ELISA mrna collagen1a1, MMP2, osteopontin, TGF-β

PSC Collagen Ring around Bile Ducts pv

Are MFBs Fibrosers? Activated BECs produce collagen I Xia et al, Am J Pathol 2006

Summary II: Concept of Biliary Fibrosis Bile acids do not induce MFB activation/proliferation MFBs have low expression levels for transporters and NRs Bile acids do not induce collagen expression in bile duct epithelial cells (BECs) TGF-β induces collagen expression in BECs Questions: Interplay between different cell types? Primary trigger for activation of BECs?

Questions YOU are currently entertaining What have we learned from mouse models?

Mdr2 -/- Develop SC and Biliary Fibrosis 4 CD4 CD4 TNF-α IL-1β CD8 5 CD4 CD4 CD4 TGF-β 3 2 1 bd 6 Fickert et al, Gastroenterology 2004;12:261

Periductal Fibrosis in LCA-fed Mice Ki-67 α-sma Sirius red ha bd ha bd bd pv ha pv Control pv ha ha bd pv ha bd pv ha bd LCA Fickert et al, Am J Pathol 2006; 168:410

Summary III: Mouse Models for Biliary Fibrosis Several mouse models for biliary fibrosis established: CBDL, DDC, LCA, Mdr2 -/- There are reactive BECs Questions: Causes and Consequences? Role of bile acids? Cytokines/Chemokines? Inflammatory cells?

Questions YOU are currently entertaining How could bile acids be a therapeutic tool in liver fibrosis?

Sirius Red norudca Reverses Biliary Fibrosis in Mdr2 -/- (KO) Mice WT Hydroxyproline (μg/g Liver) 450 400 350 300 250 200 150 100 50 0 bd 1 2 3 4 WT KO * KO KO+UDCA KO+UDCA * KO+norUDCA KO+norUDCA p<005 * vs WT vs KO Fickert et al, Gastroenterology 2006; 130: 465

Summary III: Bile Acids as a Therapeutic Tool in Biliary Fibrosis Some bile acids are antifibrotic in animal models Questions: Is there a direct antifibrotic effect? Consequence of rescuing the reactive phenotype of BECs?

Problems we have to resolve: What drives ductular proliferation? Is ductular reaction/proliferation a prerequisite for portal-portal bridging/biliary type of liver fibrosis? Are bile acids engaged in the proliferative response of MFBs? Are the effects of norudca direct/indirect?

Experimental and Molecular Hepatology Graz Center of Basic Medical Research