Intraductal papillary neoplasm of the bile duct: Radiologic findings in a new disease. / Neoplasia papilar intraductal de la vía biliar: radiología en una nueva entidad.

Intraductal papillary neoplasm of the biliary tract (B-IPN) is a scarcely known entity in our daily practice due to its low prevalence. Until its new definition in the fourth edition of the WHO classification of the digestive tract tumors of 2010 the disease was grouped under a heterogeneous and imprecise terminology. In addition, in recent years there has been progress in the knowledge of its etiopathogenesis, its natural history and its findings in image. The purpose of this paper is to review these data underlining the radiological findings of the disease and its differential diagnosis.

A morphogenetic EphB/EphrinB code controls hepatopancreatic duct formation.

The hepatopancreatic ductal (HPD) system connects the intrahepatic and intrapancreatic ducts to the intestine and ensures the afferent transport of the bile and pancreatic enzymes. Yet the molecular and cellular mechanisms controlling their differentiation and morphogenesis into a functional ductal system are poorly understood. Here, we characterize HPD system morphogenesis by high-resolution microscopy in zebrafish. The HPD system differentiates from a rod of unpolarized cells into mature ducts by de novo lumen formation in a dynamic multi-step process. The remodeling step from multiple nascent lumina into a single lumen requires active cell intercalation and myosin contractility. We identify key functions for EphB/EphrinB signaling in this dynamic remodeling step. Two EphrinB ligands, EphrinB1 and EphrinB2a, and two EphB receptors, EphB3b and EphB4a, control HPD morphogenesis by remodeling individual ductal compartments, and thereby coordinate the morphogenesis of this multi-compartment ductal system.

Generation of hepatobiliary organoids from human induced pluripotent stem cells.

BACKGROUND & AIMS: Human induced pluripotent stem cell (hiPSC)-derived liver modeling systems have the potential to overcome the shortage of donors for clinical application and become a model for drug development. Although several strategies are available to generate hepatic micro-tissues, few have succeeded in generating a liver organoid with hepatobiliary structure from hiPSCs. METHODS: At differentiation stages I and II (day 1-15), 25% of mTeSR™ culture medium was added to hepatic differentiation medium to induce endodermal and mesodermal commitment and thereafter hepatic and biliary co-differentiation. At stage III (day 15-45), 10% cholesterol+ MIX was added to the maturation medium to promote the formation and maturation of the hepatobiliary organoids. Phenotypes and functions of organoids were determined by specific markers and multiple functional assays both in vitro and in vivo. RESULTS: In this system, hiPSCs were induced to form 3D hepatobiliary organoids and to some extent recapitulated key aspects of early hepatogenesis in a parallel fashion. The organoids displayed a series of functional attributes. Specifically, the induced hepatocyte-like cells could take up indocyanine green, accumulate lipid and glycogen, and displayed appropriate secretion ability (albumin and urea) and drug metabolic ability (CYP3A4 activity and inducibility); the biliary structures in the system showed gamma glutamyltransferase activity and the ability to efflux rhodamine and store bile acids. Furthermore, after transplantation into the immune-deficient mice, the organoids survived for more than 8 weeks. CONCLUSION: This is the first time that functional hepatobiliary organoids have been generated from hiPSCs. The organoid model will be useful for in vitro studies of the molecular mechanisms of liver development and has important potential in the therapy of liver diseases. LAY SUMMARY: Herein, we established a system to generate human induced pluripotent stem cell-derived functional hepatobiliary organoids in vitro, without any exogenous cells or genetic manipulation. To some extent this model was able to recapitulate several key aspects of hepatobiliary organogenesis in a parallel fashion, holding great promise for drug development and liver transplantation.

Frequency of bile duct confluence variations in subjects with pancreas divisum: an analysis of MRCP findings.

PURPOSE: We aimed to evaluate the frequency of bile duct branching pattern variations at the hepatic confluence in patients with pancreas divisum (PD). METHODS: A search was performed through the hospital database using the keyword "pancreas divisum" to identify patients. The magnetic resonance cholangiopancreatography (MRCP) images of 137 patients who were diagnosed with PD between August 2011 and November 2016 were retrospectively analyzed for the presence of bile duct variations. A control group of 137 patients without PD was established among patients investigated during the same period. Variations of the biliary tract were grouped into seven types according to the McSweeney et al. classification. RESULTS: Biliary tract variations were detected in 103 of a total of 274 patients. Fifty-eight PD patients (42.3%) and 45 control patients (32.8%) had bile duct variation at the hepatic confluence level. The patients with PD were more likely to have biliary tract variation compared with the control group; however, it was not statistically significant (P = 0.105). The most common variation in PD patients was type 3a variation (16.8%). CONCLUSION: MRCP studies showed atypical bile duct confluence pattern in nearly half of both PD patients and controls. There was no statistically significant difference in the frequency of anatomic variations at bile duct confluence in patients with PD versus those without PD. Derivation of these structures from different outpouchings in early embryological life may explain this insignificant difference.

Self-assembled liver organoids recapitulate hepatobiliary organogenesis in vitro.

Several three-dimensional cell culture systems are currently available to create liver organoids. In gneral, these systems display better physiologic and metabolic aspects of intact liver tissue compared with two-dimensional culture systems. However, none reliably mimic human liver development, including parallel formation of hepatocyte and cholangiocyte anatomical structures. Here, we show that human fetal liver progenitor cells self-assembled inside acellular liver extracellular matrix scaffolds to form three-dimensional liver organoids that recapitulated several aspects of hepatobiliary organogenesis and resulted in concomitant formation of progressively more differentiated hepatocytes and bile duct structures. The duct morphogenesis process was interrupted by inhibiting Notch signaling, in an attempt to create a liver developmental disease model with a similar phenotype to Alagille syndrome. Conclusion: In the current study, we created an in vitro model of human liver development and disease, physiology, and metabolism, supported by liver extracellular matrix substrata; we envision that it will be used in the future to study mechanisms of hepatic and biliary development and for disease modeling and drug screening. (Hepatology 2018;67:750-761).

Molecular mechanisms of Sox transcription factors during the development of liver, bile duct, and pancreas.

The liver and pancreas are the prime digestive and metabolic organs in the body. After emerging from the neighboring domains of the foregut endoderm, they turn on distinct differentiation and morphogenesis programs that are regulated by hierarchies of transcription factors. Members of SOX family of transcription factors are expressed in the liver and pancreas throughout development and act upstream of other organ-specific transcription factors. They play key roles in maintaining stem cells and progenitors. They are also master regulators of cell fate determination and tissue morphogenesis. In this review, we summarize the current understanding of SOX transcription factors in mediating liver and pancreas development. We discuss their contribution to adult organ function, homeostasis and injury responses. We also speculate how the knowledge of SOX transcription factors can be applied to improve therapies for liver diseases and diabetes.

"Biliary Diseases with Pancreatic Counterparts": Cross-sectional Imaging Findings.

On the basis of the similarities in the histopathologic findings and the clinical-biologic behaviors of select biliary and pancreatic conditions, a new disease concept, "biliary diseases with pancreatic counterparts," has been proposed. Both nonneoplastic and neoplastic pathologic conditions of the biliary tract have their counterparts in the pancreas. Immunoglobulin G4 (IgG4)-related sclerosing cholangitis is the biliary manifestation of IgG4-related sclerosing disease, and type 1 autoimmune pancreatitis is its pancreatic counterpart. People with chronic alcoholism can develop peribiliary cysts and fibrosis as well as pancreatic fibrosis and chronic pancreatitis simultaneously. Pancreatic ductal adenocarcinoma, intraductal papillary mucinous neoplasm, and mucinous cystic neoplasm are considered pancreatic counterparts for the biliary neoplasms of extrahepatic cholangiocarcinoma, intraductal papillary neoplasm of the biliary tract, and hepatic mucinous cystic neoplasm, respectively. The anatomic proximity of the biliary tract and the pancreas, the nearly simultaneous development of both organs from the endoderm of the foregut, and the presence of pancreatic exocrine acini within the peribiliary glands surrounding the extrahepatic bile ducts are suggested as causative factors for these similarities. Interestingly, these diseases show "nearly" identical findings at cross-sectional imaging, an observation that further supports this new disease concept. New information obtained with regard to biliary diseases can be used for evaluation of pancreatic abnormalities, and vice versa. In addition, combined genetic and molecular studies may be performed to develop novel therapeutic targets. For both biliary and pancreatic diseases, imaging plays a pivotal role in initial diagnosis, evaluation of treatment response, efficacy testing of novel drugs, and long-term surveillance.

Ductal Plate Malformation in the Liver of Boxer Dogs: Clinical and Histological Features.

Ductal plate malformations (DPMs) represent developmental biliary disorders with a wide phenotypic spectrum. This study characterizes DPM in 30 Boxer dogs. Median age was 1.5 (range, 0.3-10.0) years, with 12 dogs <1 year. Clinical features included increased serum levels of liver enzymes (28), gastrointestinal signs (16), poor body condition (14), abdominal effusion (9), and hepatic encephalopathy (2). Additional malformations included gallbladder atresia (8), atrophied left liver (2), absent quadrate lobe with left-displaced gallbladder (1), portal vasculature atresia (left liver, 1), intrahepatic portosystemic shunt (1), and complex intrahepatic arteriovenous malformation (1). All dogs had portal tracts dimensionally expanded by a moderate-to-severe multiple small bile duct phenotype embedded in abundant extracellular matrix; 80% displayed variable portal-to-portal bridging. Quantitative analysis confirmed significantly increased fibrillar collagen and a 3-fold increased portal tract area relative to 6 Boxer and 10 non-Boxer controls. Biliary phenotype was dominated by tightly formed CK19-positive ductules, typically 10 to 15 µm in diameter, with 3 to >30 profiles per portal tract, reduced luminal apertures, and negative Ki-67 immunoreactivity. CK19-positive biliary epithelium intersected directly with zone 1 hepatocytes as a signature feature when considered with other DPM characteristics. Phenotypic variation included a multiple small bile duct phenotype (all dogs), predominantly thin-walled sacculated ducts (4), well-formed saccular ducts (4), and sacculated segmental, interlobular, and intralobular ducts (Caroli malformation, 2 dogs, one with bridging portal fibrosis). Histologic evidence of portal venous hypoperfusion accompanied increased biliary profiles in every case. We propose that this spectrum of disorders be referred to as DPM with appropriate modifiers to characterize the unique phenotypes.

Biliary atresia: From Australia to the zebrafish.

This review is based upon an invited lecture for the 52nd Annual Meeting of the British Association of Paediatric Surgeons, July 2015. The aetiology of biliary atresia (BA) is at best obscure, but it is probable that a number of causes or pathophysiological mechanisms may be involved leading to the final common phenotype we recognise clinically. By way of illustration, similar conditions to human BA are described, including biliary agenesis, which is the normal state and peculiar final pattern of bile duct development in the jawless fish, the lamprey. Furthermore, there have been remarkable outbreaks in the Australian outback of BA in newborn lambs whose mothers were exposed to and grazed upon a particular plant species (Dysphania glomulifera) during gestation. More recent work using a zebrafish model has isolated a toxic isoflavonoid, now named Biliatresone, thought to be responsible for these outbreaks. Normal development of the bile ducts is reviewed and parallels drawn with two clinical variants thought to definitively have their origins in intrauterine life: Biliary Atresia Splenic Malformation syndrome (BASM) and Cystic Biliary Atresia (CBA). For both variants there is sufficient clinical evidence, including associated anomalies and antenatal detection, respectively, to warrant their aetiological attribution as developmental BA. CMV IgM +ve associated BA is a further variant that appears separate with distinct clinical, histological, and immunohistochemical features. In these it seems possible that this involves perinatal obliteration of a normally formed duct system. Although still circumstantial, this evidence appears convincing enough to perhaps warrant a different treatment strategy. This then still leaves the most common (more than 60% in Western series) variant, now termed Isolated BA, whereby origins can only be alluded to.

LKB1 and Notch Pathways Interact and Control Biliary Morphogenesis.

BACKGROUND: LKB1 is an evolutionary conserved kinase implicated in a wide range of cellular functions including inhibition of cell proliferation, regulation of cell polarity and metabolism. When Lkb1 is inactivated in the liver, glucose homeostasis is perturbed, cellular polarity is affected and cholestasis develops. Cholestasis occurs as a result from deficient bile duct development, yet how LKB1 impacts on biliary morphogenesis is unknown. METHODOLOGY/PRINCIPAL FINDINGS: We characterized the phenotype of mice in which deletion of the Lkb1 gene has been specifically targeted to the hepatoblasts. Our results confirmed that lack of LKB1 in the liver results in bile duct paucity leading to cholestasis. Immunostaining analysis at a prenatal stage showed that LKB1 is not required for differentiation of hepatoblasts to cholangiocyte precursors but promotes maturation of the primitive ductal structures to mature bile ducts. This phenotype is similar to that obtained upon inactivation of Notch signaling in the liver. We tested the hypothesis of a functional overlap between the LKB1 and Notch pathways by gene expression profiling of livers deficient in Lkb1 or in the Notch mediator RbpJκ and identified a mutual cross-talk between LKB1 and Notch signaling. In vitro experiments confirmed that Notch activity was deficient upon LKB1 loss. CONCLUSION: LKB1 and Notch share a common genetic program in the liver, and regulate bile duct morphogenesis.

[Lineage fate decisions in normal and regenerating liver]. / Le développement des lignages hépatiques dans le foie normal et durant la régénération.

The origin of hepatocytes and cholangiocytes in embryonic and adult liver, as well as the source of stellate and sinusoidal cells, have received much attention recently, due to the availability of biological tools enabling to trace the fate of cell lineages. A model is now proposed which defines the differentiation potential of hepatoblasts, ductal plate cells and adult progenitor cells, in normal conditions and in regenerating liver. The mesodermal origin of stellate and sinusoidal cells is also established.

α1- and α5-containing laminins regulate the development of bile ducts via ß1 integrin signals.

Signals derived from basal lamina components are important for developing three-dimensional architecture of epithelial tissues. Laminins consisting of α, ß, and γ subunits in basal lamina play pivotal roles in the formation and maintenance of epithelial tissue structures. However, it remains unclear which laminin isoforms transmit signals and how epithelial cells receive them to regulate multiple developmental processes. In three-dimensional culture of a liver progenitor cell line, Hepatic Progenitor Cells Proliferating on Laminin (HPPL), the cells establish apicobasal polarity and form cysts with a central lumen. Neutralizing antibody against ß1 integrin blocked the formation and maintenance of the cyst structure, indicating that ß1 integrin signaling was necessary throughout the morphogenesis. Although the addition of α1-containing laminin, a ligand of ß1 integrin, induced cyst formation, it was dispensable for the maintenance of the cyst, suggesting that HPPL produces another ligand for ß1 integrin to maintain the structure. Indeed, we found that HPPL produced α5-containing laminin, and siRNA against laminin α5 partially inhibited the lumen formation. In fetal liver, p75NTR(+) periportal fibroblasts and bile duct epithelial cells, known as cholangiocytes, expressed α1- and α5-containing laminins, respectively. In laminin α5 KO liver, cholangiocytes normally emerged, but the number of bile ducts was decreased. These results suggest that α1-containing laminin is sufficient as a component of the basal lamina for the commitment of bipotential liver progenitors to cholangiocytes and the apicobasal polarization, whereas α5-containing laminin is necessary for the formation of mature duct structures. Thus, α1- and α5-containing laminins differentially regulate the sequential events to form epithelial tissues via ß1 integrin signals.

Bile duct expression of pancreatic and duodenal homeobox 1 in perihilar cholangiocarcinogenesis.

AIMS: Pancreatic and duodenal homeobox 1 (Pdx1) is a transcription factor that is crucial in embryogenic development and differentiation of pancreas, and its overexpression is reportedly involved in the progression of many malignancies, including pancreatic carcinoma. In this study, the role of Pdx1 was examined in cholangiocarcinogenesis. METHODS AND RESULTS: Forty-three cases of human cholangiocarcinoma (CC) and 66 cases of hepatolithiasis or primary sclerosing cholangitis (PSC) with biliary intraepithelial neoplasia (BilIN) lesions and also eight fetal and 20 adult normal livers were examined immunohistochemically. Pdx1 was constantly expressed in the nuclei of fetal bile ducts, but was virtually absent in the large bile ducts of adults. By contrast, Hairy and enhancer of split 1 (Hes1), which represses pancreatic exocrine and endocrine differentiation, was expressed frequently in the adult bile ducts. Pdx1 was expressed in 67% of invasive CCs. In large bile ducts, expression of Pdx1 increased while that of Hes1 decreased during the progression of BilIN lesions to CC. Expression of Pdx1 correlated with proliferative activities in CCs. In an in vitro study, all three CC cell lines expressed Pdx1 mRNA and protein. CONCLUSION: Up-regulation of Pdx1 is a feature of cholangiocarcinogenesis associated with chronic cholangitis. Furthermore, expression of Pdx1 in CC is related to increased proliferative activity in CCs.

Development of the bile ducts: essentials for the clinical hepatologist.

Several 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.

Immunohistochemical analyses of the kinetics and distribution of macrophages, hepatic stellate cells and bile duct epithelia in the developing rat liver.

Non-parenchymal cells in the liver consist mainly of Kupffer cells, hepatic stellate (HS) cells and cholangiocytes. To establish base-line data and clarify the nature, this study investigated immunohistochemically the kinetics of these cell populations in developing liver of F344 rats. Samples were collected from fetuses on days 18 and 20, neonates on days 1, 4, 8, 15, and 21, and adults at weeks 5-35. ED1 (CD68)-positive macrophages showed highest number as early as fetal day 18, and then decreased gradually until adulthood. The numbers of macrophages reacting to ED2 (CD163), OX6 (MHC II), and SRA-E5 (scavenger receptor A, CD204) increased after birth (early neonates), and ED2- and SRA-E5-positive cell numbers were maintained until adulthood, but OX6-positive cell number decreased at late stages of neonates and adulthood. ED2- and SRA-E5-positive cells appeared along sinusoids, indicating Kupffer cells, whereas OX6-positive cells were limited in Glisson's sheath. Vimentin-positive HS cells were seen consistently from fetuses to adulthood. Desmin- and glial fibrillary acidic protein (GFAP)-positive HS cells tended to be seen in fetuses and early stages of neonates. HS cells reacting to α-smooth muscle actin (α-SMA) were not detectable. Cholangiocytes, reacting to cytokeratin 19 and AE1/AE3, began to be seen on fetus day 18 with faint reaction, and interlobular bile ducts were completed in Glisson's sheath by neonatal day 8. This study shows that there are heterogeneous macrophage populations and that HS cells can show various cytoskeletal proteins in rat hepatogenesis.

Fetal intrahepatic gallbladder and topographical anatomy of the liver hilar region and hepatocystic triangle.

The fetal gallbladder (GB) is embedded in a deep fossa surrounded by the liver parenchyma. Using 15 specimens with intrahepatic GB (crown-rump length 45-92 mm; approximately 9-13 weeks of gestation), we assessed the fetal topographical anatomy of the hepatocystic triangle and the porta hepatis. The cystic duct displayed a long upward course (0.9-4.5 mm along the supero-inferior axis) from the GB, along the duodenum, to the common bile duct in the hepatoduodenal ligament, via an independent mesentery separated from liver parenchyma by a recess of the peritoneal cavity. Notably, the course varied in length among specimens, not among stages. At the porta hepatis, we were able to distinguish the supraportal course of the posterior right hepatic duct overriding a portal vein branch to segment 8 (6/15) from the other, infraportal course (9/15). In the latter type, the portal vein bifurcation was superior to the cystic duct course. Two margins of the hepatocyctic triangle were very long in fetuses because of the inferiorly located intrahepatic GB. Thus, the triangle seems to be difficult to identify in prenatal ultrasound. During changes in location after 9 weeks, the GB fundus remains attached to the liver because the cystic artery was often embedded in the liver parenchyma. A failure in the embedding and re-exposure process of the GB may result in anomalous peritoneal folds around the GB.

Understanding choledochal malformation.

Choledochal malformations (also known as choledochal cysts) may be characterised as an abnormal dilatation of the biliary tract, in the absence of any acute obstruction. Most appear to be of congenital origin probably related to distal bile duct stenosis, and almost 15% can now be detected antenatally. Excision and biliary reconstruction using a Roux loop as an open operation is still the standard to compare to. This article discusses recent advances in the understanding of their aetiology and classification together with the place of newer modalites of surgical treatment such as laparoscopic excision and biliary reconstruction. Although these are definitely feasible and safe, care should be taken before dispensing with standard open techniques which have minimal complications and proven long-term benefit.