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BACKGROUND & AIMS: Primary sclerosing cholangitis (PSC) is an orphan hepatobiliary disorder associated with inflammatory bowel disease (IBD). We aimed to estimate the risk of disease progression based on distinct clinical phenotypes in a large international cohort of patients with PSC. METHODS: We performed a retrospective outcome analysis of patients diagnosed with PSC from 1980 through 2010 at 37 centers in Europe, North America, and Australia. For each patient, we collected data on sex, clinician-reported age at and date of PSC and IBD diagnoses, phenotypes of IBD and PSC, and date and indication of IBD-related surgeries. The primary and secondary endpoints were liver transplantation or death (LTD) and hepatopancreatobiliary malignancy, respectively. Cox proportional hazards models were applied to determine the effects of individual covariates on rates of clinical events, with time-to-event analysis ascertained through Kaplan-Meier estimates. RESULTS: Of the 7121 patients in the cohort, 2616 met the primary endpoint (median time to event of 14.5 years) and 721 developed hepatopancreatobiliary malignancy. The most common malignancy was cholangiocarcinoma (n = 594); patients of advanced age at diagnosis had an increased incidence compared with younger patients (incidence rate: 1.2 per 100 patient-years for patients younger than 20 years old, 6.0 per 100 patient-years for patients 21-30 years old, 9.0 per 100 patient-years for patients 31-40 years old, 14.0 per 100 patient-years for patients 4150 years old, 15.2 per 100 patient-years for patients 51-60 years old, and 21.0 per 100 patient-years for patients older than 60 years). Of all patients with PSC studied, 65.5% were men, 89.8% had classical or large-duct disease, and 70.0% developed IBD at some point. Assessing the development of IBD as a time-dependent covariate, Crohn's disease and no IBD (both vs ulcerative colitis) were associated with a lower risk of LTD (unadjusted hazard ratio [HR], 0.62; P

Introduction: Primary sclerosing cholangitis (PSC) is an enigmatic disease with scarce therapeutic options. The clinical management of PSC remains challenging and may benefit from Outcome Indicators (OI) to assess the quality of care. Aims: This study aims to: (A) identify OIs for PSC, and (B) validate OIs in a clinical context. Methods: (A) A panel of experts generated a list of OIs by Delphi method. (B) OIs with the highest RAND/UCLA score were tested in an ongoing multicentric, prospective study (Value-based Medicine in Hepatology, VBMH). Results: Five OIs were identified having the highest rating values and low disagreement indexes: annual rate of acute cholangitis episodes (OI#1); mortality rate for patients not yet listed for liver transplantation (OI#2); rate of quality of life improvement, measured by EQ-VAS and EQ-5D (OI#3); number of patients died for cholangiocarcinoma and colo-rectal carcinoma (OI#4); incidence and/or worsening of osteoporosis (OI#5). In the validation study, 63 consecutive patients with PSC enrolled in 3 tertiary centres in Northern Italy were evaluated for a median 24-months follow-up period. For each OI, the following values were reported: (OI#1) cumulative incidence of 5.2%, resulting in 0.029 cholangitis/patient; (OI#2, OI#4) no patients died without being listed for transplantation or because of cancer during study time; (OI#3) 38.9 and 19.4% of patients showed an improvement in EQ-VAS and EQ-5D parameters, respectively; (OI#5) 3% of patients developed or worsened osteoporosis. Conclusions: Five OIs for PSC were identified reporting high consensus. Albeit the study population is small (as in the case of rare diseases) and the follow-up time is short as compared to the long natural history of the disease, these OIs have proven to be easy to collect and to work appropriately. Therefore, they are suitable to be extended to specialized centres involved in PSC management to further validate their clinical usefulness.

Genetic factors are critical in determining susceptibility to primary biliary cirrhosis (PBC), but there has not been a clear association with human leukocyte antigen (HLA) genes. We performed a multicenter case-control study and analyzed HLA class II DRB1 associations using a large cohort of 664 well-defined cases of PBC and 1992 controls of Italian ancestry. Importantly, healthy controls were rigorously matched not only by age and sex, but also for the geographical origin of the proband four grandparents (Northern, Central, and Southern Italy). After correction for multiple testing, DRB1*08 [odds ratio (OR), 3.3; 95% confidence interval (CI), 2.4-4.5] and DRB1*02 (OR 0.9; 95% CI 0.8-1.2) were significantly associated with PBC, whereas alleles DRB1*11 (OR 0.4; 95% CI 0.3-0.4) and DRB1*13 (OR 0.7; 95% CI 0.6-0.9) were protective. When subjects were stratified according to their grandparental geographical origin, only the associations with DRB1*08 and DRB1*11 were common to all three areas. Associated DRB1 alleles were found only in a minority of patients, whereas an additive genetic model is supported by the gene dosage effect for DRB1*11 allele and the interaction of DRB1*11,*13, and *08. Lastly, no significant associations were detected between speci fic DRB1 alleles and relevant clinical features represented by the presence of cirrhosis or serum autoantibodies. In conclusion, we confirm the role for HLA to determine PBC susceptibility and suggest that the effect of HLA is limited to patient subgroups. We suggest that a large whole-genome approach is required to identify further genetic elements contributing to the loss of tolerance in this disease. Copyright © 2008 by the American Association for the Study of Liver Diseases.

Background & aims: Genome-wide association studies in primary biliary cholangitis (PBC) have failed to find X chromosome (chrX) variants associated with the disease. Here, we specifically explore the chrX contribution to PBC, a sexually dimorphic complex autoimmune disease. Methods: We performed a chrX-wide association study, including genotype data from 5 genome-wide association studies (from Italy, United Kingdom, Canada, China, and Japan; 5244 case patients and 11,875 control individuals). Results: Single-marker association analyses found approximately 100 loci displaying P < 5 × 10-4, with the most significant being a signal within the OTUD5 gene (rs3027490; P = 4.80 × 10-6; odds ratio [OR], 1.39; 95% confidence interval [CI], 1.028-1.88; Japanese cohort). Although the transethnic meta-analysis evidenced only a suggestive signal (rs2239452, mapping within the PIM2 gene; OR, 1.17; 95% CI, 1.09-1.26; P = 9.93 × 10-8), the population-specific meta-analysis showed a genome-wide significant locus in East Asian individuals pointing to the same region (rs7059064, mapping within the GRIPAP1 gene; P = 6.2 × 10-9; OR, 1.33; 95% CI, 1.21-1.46). Indeed, rs7059064 tags a unique linkage disequilibrium block including 7 genes: TIMM17B, PQBP1, PIM2, SLC35A2, OTUD5, KCND1, and GRIPAP1, as well as a superenhancer (GH0XJ048933 within OTUD5) targeting all these genes. GH0XJ048933 is also predicted to target FOXP3, the main T-regulatory cell lineage specification factor. Consistently, OTUD5 and FOXP3 RNA levels were up-regulated in PBC case patients (1.75- and 1.64-fold, respectively). Conclusions: This work represents the first comprehensive study, to our knowledge, of the chrX contribution to the genetics of an autoimmune liver disease and shows a novel PBC-related genome-wide significant locus.

[BACKGROUND & AIMS] Primary biliary cholangitis (PBC) is a chronic liver disease in which autoimmune destruction of the small intra-hepatic bile ducts eventually leads to cirrhosis. Many patients have inadequate response to licensed medications, motivating the search for novel therapies. Previous genome-wide association studies (GWAS) and meta-analyses (GWMA) of PBC have identified numerous risk loci for this condition, providing insight into its aetiology. We undertook the largest GWMA of PBC to date, aiming to identify additional risk loci and prioritise candidate genes for in silico drug efficacy screening. [METHODS] We combined new and existing genotype data for 10, 516 cases and 20, 772 controls from five European and two East Asian cohorts. [RESULTS] We identified 56 genome-wide significant loci (20 novel) including 46 in European, 13 in Asian, and 41 in combined cohorts; and a 57th genome-wide significant locus (also novel) in conditional analysis of the European cohorts. Candidate genes at newly identified loci include FCRL3, INAVA, PRDM1, IRF7, CCR6, CD226, and IL12RB1, each having key roles in immunity. Pathway analysis reiterated the likely importance of pattern recognition receptor and TNF signalling, Jak-STAT signalling, and differentiation of TH1 and TH17 cells in the pathogenesis of this disease. Drug efficacy screening identified several medications predicted to be therapeutic in PBC, some well-established in the treatment of other autoimmune disorders. [CONCLUSIONS] This study has identified additional risk loci for PBC, provided a hierarchy of agents that could be trialled in this condition, and emphasised the value of genetic and genomic approaches to drug discovery in complex disorders. [Lay summary] Primary biliary cholangitis (PBC) is a chronic liver disease that eventually leads to cirrhosis. In this study, we analysed genetic information from 10, 516 people with PBC and 20, 772 healthy individuals recruited in Canada, China, Italy, Japan, UK, or USA. We identified several genetic regions associated with PBC. Each of these regions contains several genes. For each region, we used diverse sources of evidence to help us choose the gene most likely to be involved in causing PBC. We used these ‘candidate genes’ to help us identify medications that are currently used for treatment of other conditions, which might also be useful for treatment of PBC., 原発性胆汁性胆管炎のゲノムワイド関連解析 --国際メタ解析による新規疾患感受性遺伝子と治療薬候補の同定--. 京都大学プレスリリース. 2021-06-28.

In recent years, vast progress in basic science and technology has ramatically changed scientific perspectives by opening the new orizon of translational medicine. The term “translational” refers to he bench-to-bedside paradigm and addresses the process of applyng ideas, insights and discoveries generated through basic science chemistry, biology, genetics) to improve diagnosis, prevention and reatment of human diseases [1]. The bench-to-bedside process can be divided into several steps, rom basic inquiry into pathophysiology to the identification of otentially targetable pathways, up to the development of new rugs. The final track resides in clinical testing of therapeutic agents nd evaluation of their efficacy. Traditionally, these steps are perormed by independent experts, starting from the basic scientist, hrough the chemistry expert/drug developer, ending with the clincal scientist. These professionals most of the time are physically eparated, and very often use a different terminology with diffiulties in cooperation and communication. The identification of translational approach recognizes the strong need for a close nteraction between individuals in science. Furthermore, sharing nformation among players also favours feedback from the cliniian to the basic scientist, thus making research at least a two-way rocess, from bench-to-bedside and from bedside-to-bench [2]. In the last two decades, gastroenterology has become an area f dynamic translational research, with some targets already sucessfully translated into practice and policy, and some others still rogressing into clinically effective drugs in a number of different onditions (Supplementary Figure S1). Epitome of how bidirecional translation has been fruitful in this field is the discovery of he central role of the potent pro-inflammatory cytokine tumour

Cholangiocarcinoma (CCA) includes a cluster of highly heterogeneous biliary malignant tumours that can arise at any point of the biliary tree. Their incidence is increasing globally, currently accounting for ~15% of all primary liver cancers and ~3% of gastrointestinal malignancies. The silent presentation of these tumours combined with their highly aggressive nature and refractoriness to chemotherapy contribute to their alarming mortality, representing ~2% of all cancer-related deaths worldwide yearly. The current diagnosis of CCA by non-invasive approaches is not accurate enough, and histological confirmation is necessary. Furthermore, the high heterogeneity of CCAs at the genomic, epigenetic and molecular levels severely compromises the efficacy of the available therapies. In the past decade, increasing efforts have been made to understand the complexity of these tumours and to develop new diagnostic tools and therapies that might help to improve patient outcomes. In this expert Consensus Statement, which is endorsed by the European Network for the Study of Cholangiocarcinoma, we aim to summarize and critically discuss the latest advances in CCA, mostly focusing on classification, cells of origin, genetic and epigenetic abnormalities, molecular alterations, biomarker discovery and treatments. Furthermore, the horizon of CCA for the next decade from 2020 onwards is highlighted., Cholangiocarcinoma (CCA) comprises heterogeneous biliary malignant tumours, and their incidence is increasing worldwide. This expert Consensus Statement, endorsed by the ENS-CCA, summarizes the latest advances in CCA, including classification, genetics and treatment, and provides recommendations for CCA management and priorities across basic, translational and clinical research.

BACKGROUND AND AIMS: Serotonin (5HT) is a neuroendocrine hormone synthetized in the central nervous system (CNS) as well as enterochromaffin cells of the gastrointestinal tract. Tryptophan hydroxylase (TPH1) and monoamine oxidase (MAO-A) are the key enzymes for the synthesis and catabolism of 5HT, respectively. Previous studies demonstrated that 5-hydroxytryptamine receptor (5HTR)1A/1B receptor agonists inhibit biliary hyperplasia in bile-duct ligated (BDL) rats, whereas 5HTR2B receptor antagonists attenuate liver fibrosis (LF) in mice. Our aim was to evaluate the role of 5HTR2A/2B/2C agonists/antagonists in cholestatic models. APPROACH AND RESULTS: While in vivo studies were performed in BDL rats and the multidrug resistance gene 2 knockout (Mdr2(−/−)) mouse model of PSC, in vitro studies were performed in cell lines of cholangiocytes and hepatic stellate cells (HSCs). 5HTR2A/2B/2C and MAO-A/TPH1 are expressed in cholangiocytes and HSCs from BDL rats and Mdr2(−/−) mice. Ductular reaction, LF, as well as the mRNA expression of proinflammatory genes increased in normal, BDL rats, and Mdr2(−/−) mice following treatment 5HTR2A/2B/2C agonists, but decreased when BDL rats and Mdr2(−/−) mice were treated with 5HTR2A/2B/2C antagonists compared to BDL rats and Mdr2(−/−) mice, respectively. 5HT levels increase in Mdr2(−/−) mice and in PSC human patients compared to their controls and decrease in serum of Mdr2(−/−) mice treated with 5HTR2A/2B/2C antagonists compared to untreated Mdr2(−/−) mice. In vitro, cell lines of murine cholangiocytes and human HSCs express 5HTR2A/2B/2C and MAO-A/TPH1; treatment of these cell lines with 5HTR2A/2B/2C antagonists or TPH1 inhibitor decreased 5HT levels as well as expression of fibrosis and inflammation genes compared to controls. CONCLUSIONS: Modulation of the TPH1/MAO-A/5HT/5HTR2A/2B/2C axis may represent a therapeutic approach for management of cholangiopathies, including PSC.

Background & aims The impact of chronic liver diseases (CLDs) on health-related quality of life (HRQoL) is relevant to understand the burden of these conditions and inform decision-making processes related to their care. Studies simultaneously comparing the HRQoL of patients affected by the major CLDs to that of the general population are still lacking and are the subject of this study. Methods Using the EQ-5D-3L questionnaire, we analyzed and compared HRQoL data from 2,962 Italian patients affected by CLDs and forming a representative sample of general Italian population (6,800 individuals). Exploratory analyses were conducted to investigate the effects of each CLD on HRQoL, using the general population as reference and adjusting for possible confounders. Results Patients with CLDs (HBV, HCV, PSC, PBC, AIH, NAFLD/NASH) in the chronic hepatitis stage and with compensated cirrhosis (CC) showed HRQoL similar to the general population. However, AIH were more likely to report problems in self-care and lower EQ-5D VAS score, while NAFLD/NASH and HCV showed an increased risk of anxiety/depression. On the other hand, with progression to more advanced stages of liver disease (DC or HCC), HRQoL decreased significantly with higher risk of reporting problems in the physical domains, and significant reductions in the VAS and utility index scores. Conclusions Different subtypes of CLD affected different QoL domains. This study therefore provides a real estimate of the impact of CLDs on patients' HRQoL, and represents a much needed tool to inform decision-making while assessing the effectiveness and cost-effectiveness of the care of these patients.

Background & Aims Genetic defects in polycystin-1 or -2 ( PC1 or PC2 ) cause polycystic liver disease associated with autosomal dominant polycystic kidney disease (PLD-ADPKD). Progressive cyst growth is sustained by a cAMP-dependent Ras/ERK/HIFα pathway, leading to increased vascular endothelial growth factor A (VEGF-A) signaling. In PC2-defective cholangiocytes, cAMP production in response to [Ca 2+ ] ER depletion is increased, while store-operated Ca 2+ entry (SOCE), intracellular and endoplasmic reticulum [Ca 2+ ] ER levels are reduced. We investigated whether the adenylyl cyclases, AC5 and AC6, which can be inhibited by Ca 2+ , are activated by the ER chaperone STIM1. This would result in cAMP/PKA-dependent Ras/ERK/HIFα pathway activation in PC2-defective cells, in response to [Ca 2+ ] ER depletion. Methods PC2 / AC6 double conditional knockout (KO) mice were generated ( Pkd2 / AC6 KO) and compared to Pkd2 KO mice. The AC5 inhibitor SQ22,536 or AC5 siRNA were used in isolated cholangiocytes while the inhibitor was used in biliary organoid and animals; liver tissues were harvested for histochemical analysis. Results When comparing Pkd2 / AC6 KO to Pkd2 KO mice, no decrease in liver cyst size was found, and cellular cAMP after [Ca 2+ ] ER depletion only decreased by 12%. Conversely, in PC2-defective cells, inhibition of AC5 significantly reduced cAMP production, pERK1/2 expression and VEGF-A secretion. AC5 inhibitors significantly reduced growth of biliary organoids derived from Pkd2 KO and Pkd2 / AC6 KO mice. In vivo treatment with SQ22,536 significantly reduced liver cystic area and cell proliferation in PC2-defective mice. After [Ca 2+ ] ER depletion in PC2-defective cells, STIM1 interacts with AC5 but not with Orai1, the Ca 2+ channel that mediates SOCE. Conclusion [Ca 2+ ] ER depletion in PC2-defective cells activates AC5 and results in stimulation of cAMP/ERK1-2 signaling, VEGF production and cyst growth. This mechanism may represent a novel therapeutic target. Lay summary Polycystic liver diseases are characterized by progressive cyst growth until their complications mandate surgery or liver transplantation. In this manuscript, we demonstrate that inhibiting cell proliferation, which is induced by increased levels of cAMP, may represent a novel therapeutic target to slow the progression of the disease.

Background & Aims: Chronic liver diseases (CLDs) are major health problems that require complex and costly treatments. Liver-specific clinical outcome indicators (COIs) able to assist both clinicians and administrators in improving the value of care are presently lacking. The Value-Based Medicine in Hepatology (VBMH) study aims to fill this gap, devising and testing a set of COIs for CLD, that could be easily collected during clinical practice. Here we report the COIs generated and recorded for patients with HBV or HCV infection at different stages of the disease. Methods/Results: In the first phase of VBMH study, COIs were identified, based on current international guidelines and literature, using a modified Delphi method and a RAND 9-point appropriateness scale. In the second phase, COIs were tested in an observational, longitudinal, prospective, multicentre study based in Lombardy, Italy. Eighteen COIs were identified for HBV and HCV patients. Patients with CLD secondary to HBV (547) or HCV (1391) were enrolled over an 18-month period and followed for a median of 4years. The estimation of the proposed COIs was feasible in the real-word clinical practice and COI values compared well with literature data. Further, the COIs were able to capture the impact of new effective treatments like direct-acting antivirals (DAAs) in the clinical practice. Conclusions: The COIs efficiently measured clinical outcomes at different stages of CLDs. While specific clinical practice settings and related healthcare systems may modify their implementation, these indicators will represent an important component of the tools for a value-based approach in hepatology and will positively affect care delivery.

Tumour microenvironment is a complex, multicellular functional compartment that, particularly when assembled as an abundant desmoplastic reaction, may profoundly affect the proliferative and invasive abilities of epithelial cancer cells. Tumour microenvironment comprises not only stromal cells, mainly cancer-associated fibroblasts, but also immune cells of both the innate and adaptive system (tumour-associated macrophages, neutrophils, natural killer cells, and T and B lymphocytes), and endothelial cells. This results in an intricate web of mutual communications regulated by an extensively remodelled extracellular matrix, where the tumour cells are centrally engaged. In this regard, cholangiocarcinoma, in particular the intrahepatic variant, has become the focus of mounting interest in the last years, largely because of the lack of effective therapies despite its rising incidence and high mortality rates worldwide. On the other hand, recent studies in pancreatic cancer, which similarly to cholangiocarcinoma, is highly desmoplastic, have argued against a tumour-promoting function of the tumour microenvironment. In this review, we will discuss recent developments concerning the role of each cellular population and their multifaceted interplay with the malignant biliary epithelial counterpart. We ultimately hope to provide the working knowledge on how their manipulation may lead to a therapeutic gain in cholangiocarcinoma.

Bile duct epithelial cells, also known as cholangiocytes, regulate the composition ofbileand its flow. Acquired, congenital and genetic dysfunctions in these cells give rise to asetof diverse and complex diseases, often of unknown aetiology, called cholangiopathies. New knowledge has been steadily acquired about genetic and congenital cholangiopathies, and this has led to a better understanding of the mechanisms of acquired cholangiopathies. This Review focuses on findings from studies on Alagille syndrome, polycystic liver diseases, fibropolycystic liver diseases (Caroli disease and congenital hepatic fibrosis) and cystic fibrosis-related liver disease. In particular, knowledge on the role of Notch signalling in biliary repair and tubulogenesis has been advanced by work on Alagille syndrome, and investigations in polycystic liver diseases have highlighted the role of primary cilia in biliary pathophysiology and the concept of biliary angiogenic signalling and its role in cyst growth and biliary repair. In fibropolycystic liver disease, research has shown that loss of fibrocystin generates a signalling cascade that increases β-catenin signalling, activates the NOD-, LRR- and pyrin domain-containing 3 inflammasome, and promotes production of IL-1β and other chemokines that attract macrophages and orchestrate the process of pericystic and portal fibrosis, which are the main mechanisms of progression in cholangiopathies. In cystic fibrosis-related liver disease, lack of cystic fibrosis transmembrane conductance regulator increases the sensitivity of epithelial Toll-like receptor 4 that sustains the secretion of nuclear factor-κB-dependent cytokines and peribiliary inflammation in response to gut-derived products, providing a model for primary sclerosing cholangitis. These signalling mechanisms may be targeted therapeutically and they offer a possibility for the development of novel treatments for acquired cholangiopathies.

Congenital Hepatic Fibrosis (CHF) is a disease of the biliary epithelium characterized by bile duct changes resembling ductal plate malformations and by progressive peribiliary fibrosis, in the absence of overt necroinflammation. Progressive liver fibrosis leads to portal hypertension and liver failure, however the mechanisms leading to fibrosis in CHF remain elusive. CHF is caused by mutations in PKHD1, a gene encoding for fibrocystin, a ciliary protein expressed in cholangiocytes. Using a fibrocystin-defective (Pkhd1(del4/del4) ) mouse, which is orthologous of CHF, we show that Pkhd1(del4/del4) cholangiocytes are characterized by a β-catenin-dependent secretion of a range of chemokines, including CXCL1, CXCL10 and CXCL12, which stimulate bone marrow-derived macrophage recruitment. We also show that Pkhd1(del4/del4) cholangiocytes, in turn, respond to proinflammatory cytokines released by macrophages by up-regulating αvβ6 integrin, an activator of latent local TGFβ1. While the macrophage infiltrate is initially dominated by the M1 phenotype, the profibrogenic M2 phenotype increases with disease progression, along with the number of portal myofibroblasts. Consistent with these findings, clodronate-induced macrophage depletion results in a significant reduction of portal fibrosis and portal hypertension as well as of liver cysts. our results show that fibrosis can be initiated by an epithelial cell dysfunction, leading to low-grade inflammation, macrophage recruitment and collagen deposition. These findings establish a new paradigm for biliary fibrosis and represent a model to understand the relationship between cell dysfunction, parainflammation, liver fibrosis and macrophage polarization over time. This article is protected by copyright. All rights reserved.

Despite recent advances, pathogenesis of cholangiocarcinoma, a highly lethal cancer, remains enigmatic. Furthermore, treatment options are still limited and often disappointing. For this reason, in the last few years there has been a mounting interest towards the generation of experimental models able to reproduce the main features associated with this aggressive behavior. Toxic and infestation-induced, genetically engineered and cell implantation rodent models have been generated, contributing to a deeper understanding of the complex cell biology of the tumor, sustained by multiple cell interactions and driven by a huge variety of molecular perturbations. Herein, we will overview the most relevant animal models of biliary carcinogenesis, highlighting the methodological strategy, the molecular, histological and clinical phenotypes consistent with the human condition, their particular strengths and weaknesses and the novel therapeutic approaches that have been developed.

Cystic fibrosis transmembrane conductance regulator (CFTR), the channel mutated in cystic fibrosis (CF), is expressed by the biliary epithelium (i.e., cholangiocytes) of the liver. Progressive clinical liver disease (CF-associated liver disease; CFLD) occurs in around 10% of CF patients and represents the third leading cause of death. Impaired secretion and inflammation contribute to CFLD; however, the lack of human-derived experimental models has hampered the understanding of CFLD pathophysiology and the search for a cure. We have investigated the cellular mechanisms altered in human CF cholangiocytes using induced pluripotent stem cells (iPSCs) derived from healthy controls and a ΔF508 CFTR patient. We have devised a novel protocol for the differentiation of human iPSC into polarized monolayers of cholangiocytes. Our results show that iPSC-cholangiocytes reproduced the polarity and the secretory function of the biliary epithelium. Protein kinase A/cAMP-mediated fluid secretion was impaired in ΔF508 cholangiocytes and negligibly improved by VX-770 and VX-809, two small molecule drugs used to correct and potentiate ΔF508 CFTR. Moreover, ΔF508 cholangiocytes showed increased phosphorylation of Src kinase and Toll-like receptor 4 and proinflammatory changes, including increased nuclear factor kappa-light-chain-enhancer of activated B cells activation, secretion of proinflammatory chemokines (i.e., monocyte chemotactic protein 1 and interleukin-8), as well as alterations of the F-actin cytoskeleton. Treatment with Src inhibitor (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyramidine) decreased the inflammatory changes and improved cytoskeletal defects. Inhibition of Src, along with administration of VX-770 and VX-809, successfully restored fluid secretion to normal levels. Conclusion: Our findings have strong translational potential and indicate that targeting Src kinase and decreasing inflammation may increase the efficacy of pharmacological therapies aimed at correcting the basic ΔF508 defect in CF liver patients. These studies also demonstrate the promise of applying iPSC technology in modeling human cholangiopathies. (Hepatology 2018;67:972–988).

Background & Aims In cholangiocarcinoma, early metastatic spread via lymphatic vessels often precludes curative therapies. Cholangiocarcinoma invasiveness is fostered by an extensive stromal reaction, enriched in cancer-associated fibroblasts (CAFs) and lymphatic endothelial cells (LECs). Cholangiocarcinoma cells recruit and activate CAFs by secreting PDGF-D. Herein, we investigated the role of PDGF-D and liver myofibroblasts in promoting lymphangiogenesis in cholangiocarcinoma. Methods Human cholangiocarcinoma specimens were immunostained for podoplanin (LEC marker), α-SMA (CAF marker), VEGF-A, VEGF-C, and their cognate receptors (VEGFR2, VEGFR3). VEGF-A and VEGF-C secretion was evaluated in human fibroblasts obtained from primary sclerosing cholangitis explants. Using human LECs incubated with conditioned medium from PDGF-D-stimulated fibroblasts we assessed migration, 3D vascular assembly, transendothelial electric resistance and transendothelial migration of cholangiocarcinoma cells (EGI-1). We then studied the effects of selective CAF depletion induced by the BH3 mimetic navitoclax on LEC density and lymph node metastases in vivo. Results In cholangiocarcinoma specimens, CAFs and LECs were closely adjacent. CAFs expressed VEGF-A and VEGF-C, while LECs expressed VEGFR2 and VEGFR3. Upon PDGF-D stimulation, fibroblasts secreted increased levels of VEGF-C and VEGF-A. Fibroblasts, stimulated by PDGF-D induced LEC recruitment and 3D assembly, increased LEC monolayer permeability, and promoted transendothelial EGI-1 migration. These effects were all suppressed by the PDGFRβ inhibitor, imatinib. In the rat model of cholangiocarcinoma, navitoclax-induced CAF depletion, markedly reduced lymphatic vascularization and reduced lymph node metastases. Conclusion PDGF-D stimulates VEGF-C and VEGF-A production by fibroblasts, resulting in expansion of the lymphatic vasculature and tumor cell intravasation. This critical process in the early metastasis of cholangiocarcinoma may be blocked by inducing CAF apoptosis or by inhibiting the PDGF-D-induced axis. Lay summary Cholangiocarcinoma is a highly malignant cancer affecting the biliary tree, which is characterized by a rich stromal reaction involving a dense population of cancer-associated fibroblasts that promote early metastatic spread. Herein, we show that cholangiocarcinoma-derived PDGF-D stimulates fibroblasts to secrete vascular growth factors. Thus, targeting fibroblasts or PDGF-D-induced signals may represent an effective tool to block tumor-associated lymphangiogenesis and reduce the invasiveness of cholangiocarcinoma.

In severe liver injury, ductular reactions (DRs) containing bipotential hepatic progenitor cells (HPCs) branch from the portal tract. Neural cell adhesion molecule (NCAM) marks bile ducts and DRs, but not mature hepatocytes. NCAM mediates interactions between cells and surrounding matrix; however, its role in liver development and regeneration is undefined. Polysialic acid (polySia), a unique posttranslational modifier of NCAM, is produced by the enzymes, ST8SiaII and ST8SiaIV, and weakens NCAM interactions. The role of polySia with NCAM synthesizing enzymes ST8SiaII and ST8SiaIV were examined in HPCs in vivo using the choline-deficient ethionine-supplemented and 3,5-diethoxycarbonyl-1,4-dihydrocollidine diet models of liver injury and regeneration, in vitro using models of proliferation, differentiation, and migration, and by use of mouse models with gene defects in the polysialyltransferases (St8sia 2+/-4+/-, and St8sia2-/-4-/-). We show that, during liver development, polySia is required for the correct formation of bile ducts because gene defects in both the polysialyltransferases (St8sia2+/-4+/- and St8sia2-/-4-/- mice) caused abnormal bile duct development. In normal liver, there is minimal polySia production and few ductular NCAM+ cells. Subsequent to injury, NCAM+ cells expand and polySia is produced by DRs/HPCs through ST8SiaIV. PolySia weakens cell-cell and cell-matrix interactions, facilitating HGF-induced migration. Differentiation of HPCs to hepatocytes in vitro results in both transcriptional down-regulation of polySia and cleavage of polySia-NCAM. Cleavage of polySia by endosialidase (endoN) during liver regeneration reduces migration of DRs into parenchyma.PolySia modification of NCAM+ ductules weakens cell-cell and cell-matrix interactions, allowing DRs/HPCs to migrate for normal development and regeneration. Modulation of polySia levels may provide a therapeutic option in liver regeneration.

Cholangiocarcinoma (CCA) is a highly aggressive epithelial malignancy still carrying a dismal prognosis, owing to early lymph node metastatic dissemination and striking resistance to conventional chemotherapy. Although mechanisms underpinning CCA progression are still a conundrum, it is now increasingly recognized that the desmoplastic microenvironment developing in conjunction with biliary carcinogenesis, recently renamed tumor reactive stroma (TRS), behaves as a paramount tumor-promoting driver. Indeed, once being recruited, activated and dangerously co-opted by neoplastic cells, the cellular components of the TRS (myofibroblasts, macrophages, endothelial cells and mesenchymal stem cells) continuously rekindle malignancy by secreting a huge variety of soluble factors (cyto/chemokines, growth factors, morphogens and proteinases). Furthermore, these factors are long-term stored within an abnormally remodeled extracellular matrix (ECM), which in turn can deleteriously mold cancer cell behavior. In this review, we will highlight evidence for the active role played by reactive stromal cells (as well as by the TRS-associated ECM) in CCA progression, including an overview of the most relevant TRS-derived signals possibly fueling CCA cell aggressiveness. Hopefully, a deeper knowledge of the paracrine communications reciprocally exchanged between cancer and stromal cells will steer the development of innovative, combinatorial therapies, which can finally hinder the progression of CCA, as well as of other cancer types with abundant TRS, such as pancreatic and breast carcinomas.

Chronic diseases of the biliary tree (cholangiopathies) represent one of the major unmet needs in clinical hepatology and a significant knowledge gap in liver pathophysiology. The common theme in cholangiopathies is that the target of the disease is the biliary tree. After damage to the biliary epithelium, inflammatory changes stimulate a reparative response with proliferation of cholangiocytes and restoration of the biliary architecture, owing to the reactivation of a variety of morphogenetic signals. Chronic damage and inflammation will ultimately result in pathological repair with generation of biliary fibrosis and clinical progression of the disease. The hallmark of pathological biliary repair is the appearance of reactive ductular cells, a population of cholangiocyte-like epithelial cells of unclear and likely mixed origin that are able to orchestrate a complex process that involves a number of different cell types, under joint control of inflammatory and morphogenetic signals. Several questions remain open concerning the histogenesis of reactive ductular cells, their role in liver repair, their mechanism of activation, and the signals exchanged with the other cellular elements cooperating in the reparative process. This review contributes to the current debate by highlighting a number of new concepts derived from the study of the pathophysiology of chronic cholangiopathies, such as congenital hepatic fibrosis, biliary atresia, and Alagille syndrome.

SummarySeveral cholangiopathies result from a perturbation of developmental processes. Most of these cholangiopathies are characterised by the persistence of biliary structures with foetal configuration. Developmental processes are also relevant in acquired liver diseases, as liver repair mechanisms exploit a range of autocrine and paracrine signals transiently expressed in embryonic life. We briefly review the ontogenesis of the intra- and extrahepatic biliary tree, highlighting the morphogens, growth factors, and transcription factors that regulate biliary development, and the relationships between developing bile ducts and other branching biliary structures. Then, we discuss the ontogenetic mechanisms involved in liver repair, and how these mechanisms are recapitulated in ductular reaction, a common reparative response to many forms of biliary and hepatocellular damage. Finally, we discuss the pathogenic aspects of the most important primary cholangiopathies related to altered biliary development, i.e. polycystic and fibropolycystic liver diseases, Alagille syndrome.

In most cholangiopathies, liver diseases of different etiologies in which the biliary epithelium is the primary target in the pathogenic sequence, the central mechanism involves inflammation. Inflammation, characterized by pleomorphic peribiliary infiltrate containing fibroblasts, macrophages, lymphocytes, as well as endothelial cells and pericytes, is associated to the emergence of "reactive cholangiocytes." These biliary cells do not possess bile secretory functions, are in contiguity with terminal cholangioles, and are of a less-differentiated phenotype. They have acquired several mesenchymal properties, including motility and ability to secrete a vast number of proinflammatory chemo/cytokines and growth factors along with de novo expression of a rich receptor machinery. These functional properties enable reactive cholangiocytes to establish intimate contacts and to mutually exchange a variety of paracrine signals with the different mesenchymal cell types populating the portal infiltrate. The extensive crosstalk between the epithelial and mesenchymal compartments is the driver of liver repair mechanisms in cholangiopathies, ultimately evolving toward portal fibrosis. Herein, the authors first review the properties of the different cell types involved in their interaction, and then analyze the underlying molecular mechanisms as they relate to liver repair in cholangiopathies.

Background & Aims: Cholangiopathies are characterized by impaired cholangiocyte secretion. Ursodeoxycholic acid (UDCA) is widely used for cholangiopathy treatment, but its effects on cholangiocyte secretory functions remain unclear and are the subject of this study. Methods: Polarized mouse cholangiocytes in tubular (isolated bile-duct units [IBDU]) or monolayer configuration were obtained from wild-type (WT) and B6-129-Cftr tm1Kth and Cftr tm1Unc mice that are defective in CFTR, an adenosine 3′,5′-cyclic monophosphate (cAMP)-stimulated Cl − channel expressed in cholangiocytes. Fluid secretion was assessed by video-optical planimetry, Cl − and Ca 2+ efflux by microfluorimetry (6-methoxy- N -ethylquinolinium chloride, fura-2, and fluo-4), adenosine triphosphate (ATP) secretion by luciferin-luciferase assay, and protein kinase C (PKC) by Western blot. Results: UDCA stimulated fluid secretion and Cl − efflux in WT-IBDU but not in CFTR-KO-IBDU or in WT-IBDU exposed to CFTR inhibitors. UDCA did not affect intracellular cAMP levels but increased [Ca 2+ ]i in WT and not in CFTR-KO cholangiocytes. UDCA stimulated apical ATP secretion in WT but not in CFTR-KO cholangiocytes. UDCA-stimulated [Ca 2+ ]i increase was inhibited by suramin, a purinergic 2Y-receptor inhibitor. UDCA stimulated the translocation of PKC-α and PKC-e to the plasma membrane. UDCA-stimulated secretion was inhibited by 2-bis(2-aminophenoxy)-ethane- N , N , N' , N' -tetraacetic acid and by phospholipase C and PKC inhibitors. UDCA increased ATP output in isolated perfused livers from WT but not from CFTR-KO mice. Conclusions: Our data indicate that UDCA stimulates a CFTR-dependent apical ATP release in cholangiocytes. Secreted ATP activates purinergic 2Y receptors, and, through [Ca 2+ ]i increase and PKC activation stimulates Cl − efflux and fluid secretion. These data support the concept that CFTR plays a role in modulating purinergic signaling in secretory epithelia and suggest a novel mechanism explaining the choleretic effect of UDCA.

Background/Aims In routine examination of liver biopsies isolated ductular hyperplasia (IDH) may be the only histopathological change. Here we describe the clinical and immunophenotypic features of a number of cases retrospectively identified reviewing consecutive liver biopsies from five Italian centers over 4 years. Methods We reviewed 1235 cases biopsied for chronic liver disease (1078 for viral hepatitis). Records of cases fulfilling the inclusion criteria for IDH were reviewed to identify possible aetiologies. Biopsies showing IDH and control biopsies were studied by immunohistochemistry for cytokeratin-7, epithelial-membrane-antigen (EMA), neural-cell-adhesion-molecule (NCAM), Ki-67. Results Out of 70 biopsies fulfilling IDH criteria, 16 (22.8%) were of unknown aetiology. Patients with idiopathic IDH (age 38.2±11 years) were asymptomatic with mild, long-lasting ALT and/or γGT increases. A significant increase of well-differentiated (EMA-positive; NCAM-negative) bile ductules localized at the portal interface and inside the lobule was found in idiopathic IDH. Conclusions Idiopathic IDH was present in 10% of adults biopsied for persistent mild liver function test abnormalities unrelated to viral hepatitis. In contrast with the ductular reaction seen in many forms of liver disease, it is characterized by well-differentiated hyperplastic ductules in absence of significant inflammation, and may represent a non-specific pattern of reaction to mild liver damages.

Background & Aims: The biliary epithelium is involved both in bile production and in the inflammatory/reparative response to liver damage. Recent data indicate that inflammatory aggression to intrahepatic bile ducts results in chronic progressive cholestasis. Methods: To understand the effects of nitric oxide on cholangiocyte secretion and biliary tract pathophysiology we have investigated: (1) the effects of proinflammatory cytokines on NO production and expression of the inducible nitric oxide synthase (NOS2), (2) the effects of NO on cAMP-dependent secretory mechanisms, and (3) the immunohistochemical expression of NOS2 in a number of human chronic liver diseases. Results: Our results show that: (1) tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, synergically stimulate NO production in cultured cholangiocytes through an increase in NOS2 gene and protein expression; (2) micromolar concentrations of NO inhibit forskolin-stimulated cAMP production by adenylyl cyclase (AC), cyclic adenosine monophosphate (cAMP)-dependent fluid secretion, and cAMP-dependent Cl − and HCO 3 − transport mediated by cystic fibrosis transmembrane conductance regulator (CFTR) and anion exchanger isoform 2, respectively; (3) cholestatic effects of NO and of proinflammatory cytokines are prevented by NOS-2 inhibitors and by agents (manganese(III)-tetrakis(4-benzoic acid)porphyrin [MnTBAP], urate, trolox) able to block the formation of reactive nitrogen oxide species (RNOS); (4) NOS2 expression is increased significantly in the biliary epithelium of patients with primary sclerosing cholangitis (PSC). Conclusions: Our findings show that proinflammatory cytokines stimulate the biliary epithelium to generate NO, via NOS2 induction, and that NO causes ductular cholestasis by a RNOS-mediated inhibition of AC and of cAMP-dependent HCO 3 − and Cl − secretory mechanisms. This pathogenetic sequence may contribute to ductal cholestasis in inflammatory cholangiopathies. GASTROENTEROLOGY 2003;124:737-753

Introduction: The management of hepatocellular carcinoma (HCC) is a well-known public health problem, accounting for increasing mortality and high costs. Quality parameters able to measure clinical outcomes are still lacking. Aim of our study (Value Based Medicine in Hepatology, VBMH)was to identify and test outcome indicators (OIs) in HCC, in light of their potential use in policy decision models. Methods: A panel of experts identified a list of OIs using a modified Delphi method, according to experience and published evidence; four OIs with the highest RAND/UCLA score were tested in a prospective multicenter observational study. During 18 months, 711 HCC patients were enrolled and prospectively followed. 677 patients (95%) had at least one follow-up consultation. Median follow-up time was 14 months. Results: The first OI was 1–3–5 years survival stratified for BCLC stage or treatment (OI#1). One-year survival for BCLC stage 0/A–D was 93%, 86%, 50%, 26% respectively. One-year survival of 288 patients treated for the first time during the study was 88% for liver transplantation, 97% surgical resection, 100% ablation and 89% for TACE. The other three OIs evaluated the appropriateness of treatments: worsening of BCLC and/or CPT score after three months from a loco-regional therapy or surgical resection (OI#2), occurred in 16% of cases (76% after TACE). Recurrence of HCC within 6 months after curative treatments (OI#3) happened in 15% of patients treated, mainly after ablation (20%). Presence of severe morbidity three months after loco-regional procedure or resection, evaluated as grade≥3 according to Clavien-Dindo classification (OI#3), was found in 3% of patients treated. Conclusions: The outcome indicators identified in the VBMH study proved their feasibility in a large cohort of patients and could stand as a benchmark for healthcare providers to move towards a value-based approach in the management of HCC.

Introduction: Liver Cirrhosis (LC) is responsible for high morbidity, mortality and costs, with increasing need to improve quality of care. Aim of our study (Value Based Medicine in Hepatology Study, VBMH) was to identify outcome indicators (OIs) able to measure quality in liver diseases, including compensated (CC) and decompensated (DC) LC. Methods: A panel of hepatologists identified a list of 7 OIs for LC according to experience and published evidence, using a modified Delphi method and a standard 9-pointRANDappropriateness scale. Then, these 7 OIs were tested in clinical practice in a prospective multicenter observational study involving three tertiary centers in Italy, using a web-based electronic medical record. 1751 LC patients were enrolled in 18 months: 1004 CC and 747 DC. 92% of patients had at least two consultations in 17 months median follow-up. Results: Annual rate of decompensation in CC was 12% (OI#1). Annual incidence of 1st variceal bleeding (VB) was 2% for low-risk and 3% for high-risk varices (OI#2) indicating a significant success of primary profilaxis. Annual incidence of HCC in CC was 4.3%, with 81% patients found at early stage (OI#3), underlining the accuracy of oncologic surveillance. One-year survival after the first decompensation episode (ascites in 74% of cases) was 96%, 81% and 59% stratified for CPT score A, B, C respectively (OI#4), and 94%, 56% stratified for MELD below or above 15 (OI#5). 4% of DC patients had an episode of VB with 90% survival after 6 weeks, and 33% recurrence (OI#6). Similarly, 3% ofDCpatients had spontaneous bacterial peritonitis with 6 weeks survival of 86% and 13% recurrence (OI#7). Conclusions: The value-based OIs generated in this study performed well in a large cohort of consecutive patients, and could represent a reference tool for healthcare providers to improve care in LC.

Biliary epithelial cells (cholangiocytes) modulate bile fluidity and alkalinity absorbing and/or secreting fluid and electrolytes, particularly HCO3- and Cl-. Mechanisms responsible for transepithelial H+/HCO3- secretion in human cholangiocytes are largely unknown. Human cholangiocytes isolated by enzymatic digestion and immunomagnetic purification from normal liver tissue obtained from reduced grafts used for pediatric liver transplantation were cultured in the presence of human hepatocyte growth factor. Maintenance of cholangiocyte phenotypic features was assessed using markers such as cytokeratin 19, gamma-glutamyltranspeptidase, vimentin, factor VIII-related antigen, desmin, epithelial membrane antigen (EMA), and human epithelial antigen (HEA) 125. Intracellular pH (pHi) transients were measured microfluorimetrically 2'7'-Bis(2-carboxyethyl)-5,6, carboxyfluorescein-acetossimethylester (BCECF). In the absence of HCO3-, pHi recovery from an intracellular acid load (ammonia pre-pulse technique) was Na(+)-dependent and amiloride-inhibitable. No Na(+)-independent recovery was recorded even after stimulation with agents raising intracellular cyclic adenosine monophosphate (cAMP) concentrations. In the presence of HCO3-, recovery from an intracellular acid load required Na+, but was only partly inhibited by amiloride. In these conditions H+ extrusion was inhibited by 4,4-diisothiocyan atostilben-2,2-disulfonic acid (DIDS) and by intracellular Cl- depletion. Acute removal of extracellular Cl induced a pHi alkalinization that was inhibited by DIDS. pHi recovery from an intracellular alkaline load (isohydric CO2 changes) was Cl(-)-dependent and DIDS-inhibitable. Administration of agents raising intracellular cAMP concentrations increased both Na(+)-dependent and Na(+)-independent Cl-/HCO-3 exchange activity. Stimulation of Cl-/HCO3- exchange activity was not prevented by the Cl- channel inhibitor 5'-nitro-2(2)-phenylpropyl-amino-benzoate(NPPB). In conclusion, human cholangiocytes possess two acid extruders (Na+/H+exchanger and Na(+)-dependent Cl-/HCO3- exchange) and an acid loader (Cl-/HCO3- exchange), whereas no evidence was found for cAMP activated H(+)-ATPase. Bicarbonate influx is thus mainly mediated by Na-dependent Cl-/HCO3- exchange, whereas Na+:HCO-3 cotransport is not active in the physiological range of pHi. Stimulation of Na(+)-independent Cl-/HCO3- exchanger by cAMP does not require activation of Cl- conductances. These mechanisms may underlay hormone-regulated biliary HCO3- secretion in the human biliary tree.

Background & Aims Repair from biliary damages requires the biliary specification of hepatic progenitor cells and the remodeling of ductular reactive structures into branching biliary tubules. We hypothesized that the morphogenetic role of Notch signaling is maintained during the repair process and have addressed this hypothesis using pharmacologic and genetic models of defective Notch signaling. Methods Treatment with DDC (3,5-diethoxycarbonyl-1,4-dihydrocollidine) or ANIT (alpha-naphthyl-isothiocyanate) was used to induce biliary damage in wild type mice and in mice with a liver specific defect in the Notch-2 receptor ( Notch-2 -cKO) or in RPB-Jk. Hepatic progenitor cells, ductular reaction, and mature ductules were quantified using K19 and SOX-9. Results In DDC treated wild type mice, pharmacologic Notch inhibition with dibenzazepine decreased the number of both ductular reaction and hepatic progenitor cells. Notch-2 -cKO mice treated with DDC or ANIT accumulated hepatic progenitor cells that failed to progress into mature ducts. In RBP-Jk -cKO mice, mature ducts and hepatic progenitor cells were both significantly reduced with respect to similarly treated wild type mice. The mouse progenitor cell line BMOL cultured on matrigel, formed a tubular network allowing the study of tubule formation in vitro ; γ-secretase inhibitor treatment and siRNAs silencing of Notch-1 , Notch-2 or Jagged-1 significantly reduced both the length and number of tubular branches. Conclusions These data demonstrate that Notch signaling plays an essential role in biliary repair. Lack of Notch-2 prevents biliary tubule formation, both in vivo and in vitro . Lack of RBP-Jk inhibits the generation of biliary-committed precursors and tubule formation.

Notch signalling is an evolutionarily conserved intercellular pathway involved in many aspects of development and tissue renewal in several organs. The importance of Notch signalling in liver development and morphogenesis is well established. However, the post-natal role of Notch in liver repair/regeneration is only now beginning to be unveiled. Despite the simplicity of the pathway activation, a fine spatial-temporal regulation of Notch signalling is required to avoid pathologic effects. This review highlights recent advances in the field indicating that Notch signalling is involved in the reparative morphogenesis of the biliary tree and in liver carcinogenesis. Defective Notch signalling leads to impaired ability of the liver to repair liver damage, while excessive activation may be involved in liver cancer. Even though much remains to be understood about these mechanisms, including the cross-talk between Notch signalling and other liver morphogens, current evidence suggests that the modulation of the Notch pathway may represent a therapeutic target in chronic liver disease.

Cholangiocarcinoma (CCA) is characterized by an abundant stromal reaction. Cancer-associated fibroblasts (CAFs) are pivotal in tumor growth and invasiveness and represent a potential therapeutic target. To understand the mechanisms leading to CAF recruitment in CCA, we studied (1) expression of epithelial-mesenchymal transition (EMT) in surgical CCA specimens and CCA cells, (2) lineage tracking of an enhanced green fluorescent protein (EGFP)-expressing human male CCA cell line (EGI-1) after xenotransplantation into severe-combined-immunodeficient mice, (3) expression of platelet-derived growth factors (PDGFs) and their receptors in vivo and in vitro, (4) secretion of PDGFs by CCA cells, (5) the role of PDGF-D in fibroblast recruitment in vitro, and (6) downstream effectors of PDGF-D signaling. CCA cells expressed several EMT biomarkers, but not alpha smooth muscle actin (α-SMA). Xenotransplanted CCA masses were surrounded and infiltrated by α-SMA-expressing CAFs, which were negative for EGFP and the human Y-probe, but positive for the murine Y-probe. CCA cells were strongly immunoreactive for PDGF-A and -D, whereas CAFs expressed PDGF receptor (PDGFR)β. PDGF-D, a PDGFRβ agonist, was exclusively secreted by cultured CCA cells. Fibroblast migration was potently induced by PDGF-D and CCA conditioned medium and was significantly inhibited by PDGFRβ blockade with Imatinib and by silencing PDGF-D expression in CCA cells. In fibroblasts, PDGF-D activated the Rac1 and Cdc42 Rho GTPases and c-Jun N-terminal kinase (JNK). Selective inhibition of Rho GTPases (particularly Rac1) and of JNK strongly reduced PDGF-D-induced fibroblast migration. Conclusion: CCA cells express several mesenchymal markers, but do not transdifferentiate into CAFs. Instead, CCA cells recruit CAFs by secreting PDGF-D, which stimulates fibroblast migration through PDGFRβ and Rho GTPase and JNK activation. Targeting tumor or stroma interactions with inhibitors of the PDGF-D pathway may offer a novel therapeutic approach. (Hepatology 2013;53:1042–1053)

Polycystic Liver Disease (PLD) is characterized by multiple liver cysts that originate from the biliary epithelium and progressively enlarge, eventually causing complications related to mass effects, hemorrhages, infection or rupture(1, 2). Some patients may require cyst fenestration, liver resection and even liver transplantation(3). Most cases of PLD are associated to Autosomal Dominant Polycystic Kidney Disease (ADPKD), a genetic disease caused by mutations in PKD1 or PKD2. These genes encode polycystin-1 (PC1) and polycystin-2 (PC2) respectively, two proteins expressed by cholangiocytes(2). PC1 is localized in the primary cilium; its main function is to serve as chemosensor and a mechanosensor for the apical flow and pressure. PC1 physically interacts with PC2 (or TRPP2), a member of the transient receptor potential channels (TRP) family, that functions as a non-selective Ca2+ channel(1). PC2 is expressed in the cilium and the endoplasmic reticulum (ER), and is able to regulate cytoplasmic and ER Ca2+ concentrations. Defective PC2 function affects the resting cell [Ca2+] by reducing extracellular Ca2+ entry and altering ER Ca2+ homeostasis. In the absence of PC2, cells are unable to activate the store-operated increase Ca2+ entry mechanisms (SOCE) and respond to the subsequent reduction in ER Ca2+ levels by stimulating the activity of adenylyl cyclase 6 (AC6), a Ca2+-inhibitable AC that is not active at resting Ca2+ concentrations. This mechanism generates increased levels of cAMP(4). Inappropriate production of cAMP, the main signaling abnormality of cystic cholangiocytes, is responsible for the brisk proliferative activity of cystic cholangiocytes(5). Cyclic-AMP activates the PKA/Ras/Raf/MEK/ERK1/2 cascade, resulting in stimulation of cholangiocytes proliferation(6, 7). In addition, studies in PC2-defective cholangiocytes, have shown that the over-activation of this pathway, causes the downstream activation of the mTOR pathway and that both ERK1/2 and mTOR converge in stimulating cyclins and HIF1α-dependent VEGF-A secretion(8). Mice deficient in PC2 show a severe liver phenotype, high proliferation rate of the cystic epithelium and high expression of pERK1/2, p-mTOR, HIF1α, VEGF and VEGFR-2(7–9). The pathophysiological relevance of this model is demonstrated by the reduction of cyst growth in vivo, after administration of SU5418 (inhibition of VEGFR2 signaling)(7, 9) rapamycin (inhibition of mTOR and of VEGF production)(8) or somatostatin, that inhibits cAMP production through its receptor SSTR2(10). Clinical trials of somatostatin-analogues in PLD patients have shown only a modest reduction in cyst growth(11–13), and thus a medical treatment for patients with symptomatic PLD is still not available. Because of its role in the PKA/Ras/Raf/MEK/ERK cascade, the key signaling pathway altered in PLD, and the availability of chemical inhibitors approved for clinical use, we considered Raf as a potential new target molecule for the treatment of PLD and sought to generate experimental proof of this concept. Sorafenib is an oral Raf inhibitor used in the treatment of kidney and liver cancer that was shown to increase apoptosis and to block cell proliferation and neo-angiogenesis in a wide range of tumor models by targeting Raf/MEK/ERK signaling(14, 15). In this study, we performed in vivo and in vitro experiments to test the hypothesis that sorafenib inhibits liver cyst growth in PC2-defective mice. Contrary to our hypothesis, we found that sorafenib caused an increase in liver cyst growth in vivo and stimulated pERK, cell proliferation and Raf-1 kinase activity in Pkd2cKO cells in vitro. Inhibition of PKA restored the expected inhibitory effect of sorafenib in PC2-defective cells. Consistent with this observation, a significant reduction in liver cyst growth in vivo was achieved when sorafenib was given in combination with octreotide, an analogue of somatostatin known to inhibit cAMP production(10). These data are consistent with a model in which sorafenib inhibits B-Raf, but paradoxically activates Raf-1 in the context of PKA-dependent, Ras-induced B-Raf/Raf-1 heterodimerization. These results also suggest that the potential consequence of paradoxical activation of Raf-1 should be carefully considered when treating conditions characterized by activation of non-mutated Raf.

Notch signaling is a complex, highly conserved mechanism, originally discovered as critical regulator of cell fate determination during development in several tissues and organs.1,2 Activation of Notch may stimulate cells either to undergo a phenotypic switch or to maintain the original cell phenotype by preventing further differentiation,3 Notch is also involved in establishing organ-specific stem cell niches necessary for epithelial tissue homeostasis.3,4 The Notch system encompasses 4 genes encoding for different membrane receptors (Notch 1, 2, 3, and 4), which are activated by their binding to 5 ligands (Jagged-1, Jagged-2, and Delta-like 1, 3, and 4).4 Cell-to-cell contact is a prerequisite for the activation of Notch signaling.3,4 Whereas Notch receptors are expressed by the “receiver” cell, ligands are expressed by the “transmitter” cell. This interaction leads to the proteolytic cleavage and subsequent nuclear translocation of the intracellular domain of Notch receptors (NICD). Once migrated into the nucleus, NICD associates with the nuclear protein of the RBP-Jκ family and transcriptionally activates several other transcriptional activators or repressors that act as critical regulators of cell differentiation, apoptosis, and proliferation4 (see drawing on the left side of Figure 1). NICD is then rapidly deactivated by phosphorylation and by proteosomal degradation. The signal is maintained through ligand-induced proteolytic supply of new NICD.

During chronic injury a population of bipotent hepatic progenitor cells (HPCs) become activated to regenerate both cholangiocytes and hepatocytes. Here we show in human diseased liver and mouse models of the ductular reaction that Notch and Wnt signaling direct specification of HPCs via their interactions with activated myofibroblasts or macrophages. In particular, we found that during biliary regeneration, expression of Jagged 1 (a Notch ligand) by myofibroblasts promoted Notch signaling in HPCs and thus their biliary specification to cholangiocytes. Alternatively, during hepatocyte regeneration, macrophage engulfment of hepatocyte debris induced Wnt3a expression. This resulted in canonical Wnt signaling in nearby HPCs, thus maintaining expression of Numb (a cell fate determinant) within these cells and the promotion of their specification to hepatocytes. By these two pathways adult parenchymal regeneration during chronic liver injury is promoted. 2012 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved. Journal of Hepatology 20

Mutations in polycystins (PC1 or PC2/TRPP2) cause progressive polycystic liver disease (PLD). In PC2-defective mice, cyclic 3′,5′-adenosine monophosphate/ protein kinase A (cAMP/PKA)-dependent activation of extracellular signal-regulated kinase/ mammalian target of rapamycin (ERK-mTOR) signaling stimulates cyst growth. We investigated the mechanisms connecting PC2 dysfunction to altered Ca2+ and cAMP production and inappropriate ERK signaling in PC2-defective cholangiocytes. Cystic cholangiocytes were isolated from PC2 conditional-KO (knockout) mice (Pkd2flox/−:pCxCreER™; hence, called Pkd2KO) and compared to cholangiocytes from wild-type mice (WT). Our results showed that, compared to WT cells, in PC2-defective cholangiocytes (Pkd2KO), cytoplasmic and ER-Ca2+ (measured with Fura-2 and Mag-Fluo4) levels are decreased and store-operated Ca2+ entry (SOCE) is inhibited, whereas the expression of Ca2+-sensor stromal interaction molecule 1 (STIM1) and store-operated Ca2+ channels (e.g., the Orai1 channel) are unchanged. In Pkd2KO cells, ER-Ca2+ depletion increases cAMP and PKA-dependent ERK1/2 activation and both are inhibited by STIM1 inhibitors or by silencing of adenylyl cyclase type 6 (AC6). Conclusion: These data suggest that PC2 plays a key role in SOCE activation and inhibits the STIM-dependent activation of AC6 by ER Ca2+ depletion. In PC2-defective cells, the interaction of STIM-1 with Orai channels is uncoupled, whereas coupling to AC6 is maximized. The resulting overproduction of cAMP, in turn, potently activates the PKA/ERK pathway. PLD, because of PC2 deficiency, represents the first example of human disease linked to the inappropriate activation of store-operated cAMP production. (HEPATOLOGY 2012)

Cholangiocarcinoma (CCA) is the second most common primary malignancy of the liver; the incidence of intrahepatic CCA in Western countries has been steadily growing in the last two decades.1 In spite of the rising incidence, treatment options for CCA remain unsatisfactory,1,2 particularly because of the strong and early invasiveness of the tumor. In many patients, lymphnodal or distant metastasis or micrometastasis are present already at the time of the diagnosis, limiting and worsening the prognosis in patients otherwise eligible for surgical resection. However, a subset of patients with less aggressive CCA may even undergo liver transplantation after neoadjuvant radiochemotherapy and have excellent survival. Biomarkers able to predict tumor invasiveness and prognosis would be an important decision-making tool. Unfortunately, mechanisms that determine CCA invasiveness are largely unknown. Cancer invasiveness and metastasization requires tightly adherent epithelial cells to convert to a more motile phenotype expressing several mesenchymal features. 3 During this process, some molecular programs typical of the mesenchymal phenotype are activated, as shown by the expression of specific cell surface proteins, cytoskeletal proteins, extracellular matrix-degrading enzymes, and transcription factors.4 One such proteins is S100A4, a member of the S100 family of small calcium-binding proteins, expressed by mesenchymal cells, macrophages,5 and by epithelial cells in mesenchymal transition (EMT). Expression of S100A4 was shown to be a predictor of metastasization in colon cancer.6,7 The mechanisms of action of A100A4 depends on the cellular localization of the protein. In the cytoplasm S100A4 interacts with a number of partner proteins in cytoskeleton and in the plasma membrane (such as myosin IIa or liprin-β1). When localized in the nucleus, S100A4 may exert transcriptional functions that affect several genes, including matrix metalloproteinase (MMP)-98 and E-cadherin.9 However, the mechanism of action of S100A4 remains largely unknown, as it remains unclear whether S100A4 is just a biomarker of cancer cell aggressiveness or actually represents a functional target amenable of therapeutic intervention. While examining the expression of EMT markers in CCA specimens, we noticed that a subgroup of CCAs expressed S100A4 in the nucleus. In this study we addressed: (1) the prognostic significance of S100A4 nuclear expression in a large series of patients undergoing surgical resection, and (2) the functional relevance of S100A4 expression on the metastatic potential, motility, and invasiveness of CCA cell lines in vivo and in vitro. Our results show that nuclear expression of S100A4 by neoplastic bile ducts significantly correlated with increased metastasization and reduced survival after surgery, that human CCA cells with nuclear expression of S100A4 have a much stronger metastatic ability when xenotransplanted into severe combined immunodeficiency (SCID) mice, and that silencing S100A4 in CCA cells that originally overexpressed S100A4 significantly reduced motility and invasive capabilities in vitro.

Background & Aims Severe polycystic liver disease can complicate adult dominant polycystic kidney disease, a genetic disease caused by defects in polycystin-1 (Pkd1) or polycystin-2 (Pkd2). Liver cyst epithelial cells (LCECs) express vascular endothelial growth factor (VEGF) and its receptor, VEGFR-2. We investigated the effects of VEGF on liver cyst growth and autocrine VEGF signaling in mice with Pkd1 and Pkd2 conditional knockouts. Methods We studied mice in which Pkd1 or Pkd2 were conditionally inactivated following exposure to tamoxifen; these mice were called Pkd1 flox/− :pCxCreER (Pkd1KO) and Pkd2 flox/− :pCxCreER (Pkd2KO). Results Pkd1KO and Pkd2KO mice developed liver defects; their LCECs expressed VEGF, VEGFR-2, hypoxia-inducible factor (HIF)-1α, phosphorylated extracellular signal–regulated kinase 1/2 (pERK1/2), and proliferating cell nuclear antigen (PCNA). In Pkd2KO but not Pkd1KO mice, exposure to the VEGFR-2 inhibitor SU5416 significantly reduced liver cyst development, liver/body weight ratio, and expression of pERK and PCNA. VEGF secretion and phosphorylation of ERK1/2 and VEGFR-2 were significantly increased in cultured LCECs from Pkd2KO compared with Pkd1KO mice. Inhibition of protein kinase A (PKA) reduced VEGF secretion and pERK1/2 expression. Addition of VEGF to LCECs from Pkd2KO mice increased phosphorylated VEGFR-2 and phosphorylated mitogen signal-regulated kinase (MEK) expression and induced phosphorylation of ERK1/2; this was inhibited by SU5416. Expression of HIF-1α increased in parallel with secretion of VEGF following LCEC stimulation. VEGF-induced cell proliferation was inhibited by the MEK inhibitor U1026 and by ERK1/2 small interfering RNA. Conclusions The PKA–ERK1/2–VEGF signaling pathway promotes growth of liver cysts in mice. In Pkd2-defective LCECs, PKA-dependent ERK1/2 signaling controls HIF-1α–dependent VEGF secretion and VEGFR-2 signaling. Autocrine and paracrine VEGF signaling promotes the growth of liver cysts in Pkd2KO mice. VEGF inhibitors might be used to treat patients with polycystic liver disease.

BACKGROUND & AIMS: The HLA complex on chromosome 6p21 is firmly established as a risk locus for primary sclerosing cholangitis (PSC). We aimed to exploit genetic differences between Northern Europe and Italy in an attempt to define a causative locus in this genetic region. METHODS: Seventy-eight North-Italian PSC patients and 79 controls were included. We performed sequencing-based genotyping of HLA-C, HLA-B, and HLA-DRB1. The major histocompatibility chain-related A (MICA) transmembrane microsatellite was analysed using PCR fragment length determination. The tumour necrosis factor-alpha (TNF-alpha)-308G-->A polymorphism was genotyped with TaqMan. Allele frequencies were compared with Chi-square tests. Uncorrected p-values A. At HLA-DRB1, we confirmed positive and negative associations with DRB1*15 and DRB1*07, respectively, while there were no associations with the DRB1*03, *04 or *1301 alleles typically detected in PSC in Northern Europe. CONCLUSIONS: The strong inhibitory of the KIR ligand HLA-C2 protects against PSC development in all populations hitherto studied. Further studies on the role of natural killer cells and T-lymphocytes expressing KIRs in PSC pathogenesis are warranted. Copyright (c) 2010 European Association for the Study of the Liver

Polycystic liver disease may complicate autosomal dominant polycystic kidney disease (ADPKD), a disease caused by mutations in polycystins, which are proteins that regulate signaling, morphogenesis, and differentiation in epithelial cells. The cystic biliary epithelium [liver cystic epithelium (LCE)] secretes vascular endothelial growth factor (VEGF), which promotes liver cyst growth via autocrine and paracrine mechanisms. The expression of insulin-like growth factor 1 (IGF1), insulin-like growth factor 1 receptor (IGF1R), and phosphorylated mammalian target of rapamycin (p-mTOR) and the protein kinase A (PKA)–dependent phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) are also up-regulated in LCE. We have hypothesized that mammalian target of rapamycin (mTOR) represents a common pathway for the regulation of hypoxia-inducible factor 1 alpha (HIF1α)–dependent VEGF secretion by IGF1 and ERK1/2. Conditional polycystin-2–knockout (Pkd2KO) mice were used for in vivo studies and to isolate cystic cholangiocytes [liver cystic epithelial cells (LCECs)]. The expression of p-mTOR, VEGF, cleaved caspase 3 (CC3), proliferating cell nuclear antigen (PCNA), IGF1, IGF1R, phosphorylated extracellular signal-regulated kinase, p-P70S6K, HIF1α, and VEGF in LCE, LCECs, and wild-type cholangiocytes was studied with immunohistochemistry, western blotting, or enzyme-linked immunosorbent assays. The cystic area was measured by computer-assisted morphometry of pancytokeratin-stained sections. Cell proliferation in vitro was studied with 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and bromodeoxyuridine assays. The treatment of Pkd2KO mice with the mTOR inhibitor rapamycin significantly reduced the liver cyst area, liver/body weight ratio, pericystic microvascular density, and PCNA expression while increasing expression of CC3. Rapamycin inhibited IGF1-stimulated HIF1α accumulation and VEGF secretion in LCECs. IGF1-stimulated LCEC proliferation was inhibited by rapamycin and SU5416 (a vascular endothelial growth factor receptor 2 inhibitor). Phosphorylation of the mTOR-dependent kinase P70S6K was significantly reduced by PKA inhibitor 14-22 amide and by the mitogen signal-regulated kinase inhibitor U1026. Conclusion: These data demonstrate that PKA-dependent up-regulation of mTOR has a central role in the proliferative, antiapoptotic, and pro-angiogenic effects of IGF1 and VEGF in polycystin-2–defective mice. This study also highlights a mechanistic link between PKA, ERK, mTOR, and HIF1α-mediated VEGF secretion and provides a proof of concept for the potential use of mTOR inhibitors in ADPKD and conditions with aberrant cholangiocyte proliferation. (HEPATOLOGY 2010.)

Hyperbilirubinemia is a common laboratory finding in clinical practice, being found in several haematological and liver diseases as well as in familial conditions (5-10% in Western countries). Although most of the familial forms of hyperbilirubinemia are classically viewed as benign conditions, they have gained an increased interest in the last few years since recent data have indicated that subjects with an impaired bilirubin metabolism may have an increased susceptibility to drug toxicity. The authors briefly review the main steps of bilirubin metabolism, with a special emphasis on the emerging concepts on the molecular mechanisms of regulation by nuclear receptors (NRs) and genetic factors. Then the different forms of isolated hyperbilirubinemia occurring in both adults and paediatrics are systematically analysed, and a new categorisation is also proposed in light of the recent advances in bilirubin research. Finally, a diagnostic algorithm is discussed, along with a correct approach to its management, in order to avoid unnecessary medical investigations. © 2009.

Intrahepatic bile ducts maintain a close anatomical relationship with hepatic arteries. During liver ontogenesis, the development of the hepatic artery appears to be modulated by unknown signals originating from the bile duct. Given the capability of cholangiocytes to produce angiogenic growth factors and influence peribiliary vascularization, we studied the immunohistochemical expression of vascular endothelial growth factor (VEGF), angiopoietin-1, angiopoietin-2, and their cognate receptors (VEGFR-1, VEGFR-2, Tie-2) in fetal human livers at different gestational ages and in mice characterized by defective biliary morphogenesis (Hnf6(-/-)). The results showed that throughout the different developmental stages, VEGF was expressed by developing bile ducts and angiopoietin-1 by hepatoblasts, whereas their cognate receptors were variably expressed by vascular cells according to the different maturational stages. Precursors of endothelial and mural cells expressed VEGFR-2 and Tie-2, respectively. In immature hepatic arteries, endothelial cells expressed VEGFR-1, whereas mural cells expressed both Tie-2 and Angiopoietin-2. In mature hepatic arteries, endothelial cells expressed Tie-2 along with VEGFR-1. In early postnatal Hnf6(-/-) mice, VEGF-expressing ductal plates failed to incorporate into the portal mesenchyma, resulting in severely altered arterial vasculogenesis. CONCLUSION: The reciprocal expression of angiogenic growth factors and receptors during development supports their involvement in the cross talk between liver epithelial cells and the portal vasculature. Cholangiocytes generate a VEGF gradient that is crucial during the migratory stage, when it determines arterial vasculogenesis in their vicinity, whereas angiopoietin-1 signaling from hepatoblasts contributes to the remodeling of the hepatic artery necessary to meet the demands of the developing epithelium.

Background and aim To clarify the precise mode of inheritance of Gilbert syndrome, an unconjugated familial hyperbilirubinemia, where impaired bilirubin conjugation is caused by reduced UGT1A1 activity determined by a defective function of the A(TA)6TAA promoter region of the UGT1A1 gene. Subjects and methods Serum bilirubin levels were measured in a large, homogeneous resident population from North-Eastern Italy, consisting of 1.639 males (age 44.5 ± 13.9, range 18–89 years), and 1.420 females (age 45.1 ± 15.0, range 18–85). In 112 nuclear families from hyperbilirubinemic probands living in the same area a complex segregation analysis was then performed. In both samples we carefully excluded potentially confounding factors of bilirubin levels (alcohol abuse, excessive cigarette smoking, drug consumption, overt haemolysis and liver disease). Results Mean serum bilirubin concentrations are higher in males than in females, showing fluctuations through the different age periods in males. Complex segregation results demonstrate that unconjugated hyperbilirubinemia exhibits a precise mode of inheritance in which a major recessive gene with a frequency of 0.45 is responsible for higher serum bilirubin values. Conclusions This major recessive gene accounts only for a part of the serum bilirubin concentration, thus implying additional, environmental factors for the clinical appearance of GS.

Background and Aims: Primary sclerosing cholangitis (PSC) is an enigmatic disease with scarce therapeutic options, potentially evolving to severe and life-threatening complications, including malignancies like cholangiocarcinoma (CCA) or colon cancer. The clinical management of PSC remains challenging and may benefit from identification of outcome indicators to assess the quality of care. This study aims to: (A) identify Outcome Indicators (OIs) for PSC, and (B) validate OIs in a clinical context with a preliminary interim analysis. Methods: (A) A panel of experts generated a list of OIs using a modified version of the Delphi method. (B) OIs with the highest RAND/UCLA score were tested in an ongoing multicentric and prospective study (Value-based Medicine in Hepatology, VBMH). Results: Five OIs were identified on the basis of the highest rating values and disagreement indexes next to 0. They include: annual rate of acute cholangitis episodes (OI#1); mortality rate for patients not yet listed for liver transplantation (OI#2); rate of quality of life improvement, measured by EQ-VAS (a visual assessment scale ranging from 0 to 100 where the patient points out his present-day health status) and EQ-5D (assessment of 5 domains that measure daily performance according to 3 levels of severity) (OI#3); number of patients died for CCA and CRC (OI#4); incidence and/or worsening of osteoporosis, expressed as T-score differential over a 2-year interval (OI#5). In the validation study, 63 consecutive patients with PSC enrolled in 3 tertiary liver centres in Northern Italy were evaluated for a 24-month follow-up period. For each OI, the following values were reported: OI#1: cumulative incidence of 5.2%, resulting in 0.029 cholangitis/patient; OI#2, OI#4: no patients died without being listed for transplantation or because of cancer during study time; OI#3: 38.9% and 19.4% of patients showed an improvement in EQ-VAS and EQ-5D parameters, respectively; OI#5: 3% of patients developed or worsened osteoporosis. Conclusions: Five OIs for PSC were identified on a highly shared consensus. Albeit the study population is small (as in the case of rare diseases) and the follow-up time is short as compared to the long natural history of the disease, these OIs have proven to be easy to collect and to work appropriately. Therefore, they are suitable to be extended to specialized centres involved in PSC management to further validate their clinical usefulness.

Liver involvement in autosomal dominant polycystic kidney disease (ADPKD) is characterized by altered remodeling of the embryonic ductal plate (DP) with presence of biliary cysts and aberrant portal vasculature. The genetic defect causing ADPKD has been identified, but mechanisms of liver cyst growth remain uncertain. To investigate the possible role of angiogenic mechanisms, we have studied the immunohistochemical expression of vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2) and their receptors (VEGFR-1, VEGFR-2, Tie-2) in ADPKD, Caroli's disease, normal and fetal livers. In ADPKD and control livers Ang-1 and Ang-2 gene expression was studied by real-time-PCR. Effects of VEGF on cholangiocyte proliferation were studied by PCNA Western Blot in isolated rat cholangiocytes and by MTS assay in cultured cholangiocytes isolated from ADPKD patients and from an ADPKD mouse model (Pkd2(WS25/-)). Cholangiocytes were strongly positive for VEGF, VEGFR-1, VEGFR-2 and Ang-2 in ADPKD and Caroli, and also for Ang-1 and Tie-2 in ADPKD, similar to fetal ductal plate cells. VEGF stimulated proliferation in both normal and ADPKD cholangiocytes, but the effect was particularly evident in the latter. Ang-1 alone had no effect, but was synergic to VEGF. VEGF expression on cholangiocytes positively correlated with microvascular density. In conclusion, consistent with the immature phenotype of the cystic epithelium, expression of VEGF, VEGFRs, Ang-1 and Tie-2 is strongly upregulated in cholangiocytes from polycystic liver diseases. VEGF and Ang-1 have autocrine proliferative effect on cholangiocyte growth and paracrine effect on portal vasculature, thus promoting the growth of the cysts and their vascular supply. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

Background/Aims : The understanding of the physiology and function of human biliary epithelial cells (hBEC) has been improved by studies in monolayer culture systems. The aim was to develop a polarized model to elucidate the mechanisms of ductular morphogenesis and functional differentiation of hBEC. Methods : The morphological, phenotypic and functional properties of hBEC cultured as three-dimensional aggregates in collagen gel were assessed in medium supplemented with (or without) human hepatocyte growth factor (hHGF) and foetal bovine serum. Results : In the absence of added mitogens and serum, cells maintained as morphologically polarized aggregates, organized around a central lumen, were positive for phenotypic markers of biliary epithelium and negative for markers of other cell types. Functional markers, gamma-glutamyl-transferase, anion exchanger-2, responses to gamma interferon and forskolin induced secretion, were preserved. hHGF increased both the size and number of aggregates and induced hBEC to invade the gel and lumena forming anastomosing networks of cells. Conclusions : Collagen gel culture in the absence of added growth factors and serum provides a model for analysis of the polarized functions of hBEC. The formation of poorly organized cords of cells in response to hHGF suggests that collagen gel culture may provide a model for the investigation of atypical ductular morphogenesis of the human biliary tract.