Embryonic cholecystitis and defective gallbladder contraction in the Sox17-haploinsufficient mouse model of biliary atresia.

The gallbladder excretes cytotoxic bile acids into the duodenum through the cystic duct and common bile duct system. Sox17 haploinsufficiency causes biliary atresia-like phenotypes and hepatitis in late organogenesis mouse embryos, but the molecular and cellular mechanisms underlying this remain unclear. In this study, transcriptomic analyses revealed the early onset of cholecystitis in Sox17+/- embryos, together with the appearance of ectopic cystic duct-like epithelia in their gallbladders. The embryonic hepatitis showed positive correlations with the severity of cholecystitis in individual Sox17+/- embryos. Embryonic hepatitis could be induced by conditional deletion of Sox17 in the primordial gallbladder epithelia but not in fetal liver hepatoblasts. The Sox17+/- gallbladder also showed a drastic reduction in sonic hedgehog expression, leading to aberrant smooth muscle formation and defective contraction of the fetal gallbladder. The defective gallbladder contraction positively correlated with the severity of embryonic hepatitis in Sox17+/- embryos, suggesting a potential contribution of embryonic cholecystitis and fetal gallbladder contraction in the early pathogenesis of congenital biliary atresia.

Association between rs17095355 polymorphism on 10q24 and susceptibility to biliary atresia: a meta-analysis.

OBJECTIVE: Recent studies have identified 10q24-rs17095355 as a susceptibility locus for biliary atresia (BA). To more precisely estimate the association between the rs17095355 polymorphism and BA risk, a meta-analysis was performed. METHODS: A comprehensive search was conducted to examine all the eligible studies by electronic databases including Elsevier Science Direct, Pubmed, Google Scholar, China National Knowledge Infrastructure (CNKI) and Chinese Biomedical Literature (CBM) up to December 2015. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of the association. RESULTS: A total of 6 comparisons from 5 relevant studies involving 1000 patients and 3257 controls were included to analyze the association between rs17095355 and BA risk. The pooled OR for T allele of rs17095355 was 1.72 (95%CI 1.53-1.92, p < 0.01) in BA. Stratification by ethnicity indicated the degree of risk of rs17095355 with BA susceptibility was similar in populations of Asian origin. The pooled OR was 1.81 (95%CI 1.60-2.06, p < 0.01). CONCLUSIONS: This meta-analysis confirms the association of rs17095355 polymorphism and BA development, especially in Asians. More original studies with large sample are needed to replicate this genetic association in different ethnic groups.

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.

Hsp90 and hepatobiliary transformation during sea lamprey metamorphosis.

BACKGROUND: Biliary atresia (BA) is a human infant disease with inflammatory fibrous obstructions in the bile ducts and is the most common cause for pediatric liver transplantation. In contrast, the sea lamprey undergoes developmental BA with transient cholestasis and fibrosis during metamorphosis, but emerges as a fecund adult. Therefore, sea lamprey liver metamorphosis may serve as an etiological model for human BA and provide pivotal information for hepatobiliary transformation and possible therapeutics. RESULTS: We hypothesized that liver metamorphosis in sea lamprey is due to transcriptional reprogramming that dictates cellular remodeling during metamorphosis. We determined global gene expressions in liver at several metamorphic landmark stages by integrating mRNA-Seq and gene ontology analyses, and validated the results with real-time quantitative PCR, histological and immunohistochemical staining. These analyses revealed that gene expressions of protein folding chaperones, membrane transporters and extracellular matrices were altered and shifted during liver metamorphosis. HSP90, important in protein folding and invertebrate metamorphosis, was identified as a candidate key factor during liver metamorphosis in sea lamprey. Blocking HSP90 with geldanamycin facilitated liver metamorphosis and decreased the gene expressions of the rate limiting enzyme for cholesterol biosynthesis, HMGCoA reductase (hmgcr), and bile acid biosynthesis, cyp7a1. Injection of hsp90 siRNA for 4 days altered gene expressions of met, hmgcr, cyp27a1, and slc10a1. Bile acid concentrations were increased while bile duct and gall bladder degeneration was facilitated and synchronized after hsp90 siRNA injection. CONCLUSIONS: HSP90 appears to play crucial roles in hepatobiliary transformation during sea lamprey metamorphosis. Sea lamprey is a useful animal model to study postembryonic development and mechanisms for hsp90-induced hepatobiliary transformation.

Anatomy and embryology of the biliary tract.

Working knowledge of extrahepatic biliary anatomy is of paramount importance to the general surgeon. The embryologic development of the extrahepatic biliary tract is discussed in this article as is the highly variable anatomy of the biliary tract and its associated vasculature. The salient conditions related to the embryology and anatomy of the extrahepatic biliary tract, including biliary atresia, choledochal cysts, gallbladder agenesis, sphincter of Oddi dysfunction, and ducts of Luschka, are addressed.

Endodermal and mesenchymal cross talk: a crossroad for the maturation of foregut organs.

The developmental stages of each foregut organ are intimately linked to the development of the other foregut organs such that the ultimate function of any one foregut organ, such as the metabolic function of the liver, depends on organizational changes associated with the maturation of multiple foregut organs. These changes include: (i) proliferation of the intrahepatic bile ducts and hepatoblasts within the liver coinciding with parenchymal expansion, (ii) elongation of extrahepatic bile ducts, which allows for proper gallbladder (GB) formation, and (iii) duodenal elongation and rotation, which coincides with all of the above to connect the intrahepatic, extrahepatic, and pancreatic ductal systems with the intestine. It is well established that cross talk between endodermal and mesenchymal components of the foregut occurs, particularly regarding the vascularization of developing organs. Furthermore, genetic mutations in mesenchymal and hepatic compartments of the developing foregut result in similar foregut pathologies: hypoplastic liver, absence of GB, biliary atresia (intrahepatic and/or extrahepatic), and failure of gut elongation and rotation. Finally, these shared pathologies can be linked to deficiencies in genes specific to the septum transversum mesenchyme (Hes1, Hlx, and Foxf1) or liver (Hhex and Hnf6), illustrating the complexity of such cross talk.

Maternal microchimerism in biliary atresia.

BACKGROUND: The aim of this study was to determine the existence and extent of maternal microchimerism in the livers of biliary atresia (BA) patients. METHODS: Two series of investigations were performed based on the sex of our subjects. Subjects for series I were men, of which 6 had BA. Livers were analyzed using X and Y chromosome probes and fluorescent in situ hybridization. Subjects for series II were woman. Nine BA cases and their mothers were HLA typed (class I). Daughter livers were also tested for antibodies to maternal and other HLA. Two cases of neonatal hepatitis, 2 cases of Alagille syndrome, and 1 case of Byler syndrome acted as controls. RESULTS: All male BA livers were found to contain a mixture of cells with 1 and 2 X chromosomes (ie, XY or XX). All livers from male controls had only 1 X chromosome (ie, XY). All female BA subjects had varying intensities of antimaternal HLA class I (HLA-A) antibodies in their bile duct epithelium and hepatocytes (strong, 5; mild, 3; weak, 1). The liver from the female control did not display any antimaternal HLA class I antibodies (HLA-Ab). CONCLUSION: Our preliminary data appear to show that maternal microchimerism is present within the livers of patients with progressive postnatal type BA. We suggest that BA could in fact be a graft-vs-host disease masquerading as an autoimmune reaction triggered by maternal microchimerism, and we intend to pursue this hypothesis further to clarify the etiology of BA.

Embryonic biliary atresia in a very-low-birth-weight premature infant.

Two major forms of biliary atresia, the embryonic and perinatal type, are considered to have different pathogeneses and distinct prognoses. Embryonic biliary atresia is associated with worse prognosis. We report a case of embryonic biliary atresia in a preterm male infant of 31 weeks of gestation and weighing 1375 g, with the initial manifestation of intermittent acholic stool 5 days after birth. Kasai portoenterostomy was per-formed at the age of 51 days when he weighed 2164 g. Nevertheless, poorly restored bile flow and progressive cholestasis led to early liver transplantation at the age of 8 months. Liver function had recovered to normal levels by the age of 12 months. Diagnosis of biliary atresia in preterm infants is difficult and requires a high index of suspicion and careful workup. This case illustrates the poor outcome of embryonic biliary atresia and that early liver transplantation may be necessary to improve the prognosis.

Potential etiologies of biliary atresia.

Biliary atresia is the most common cause of neonatal cholestasis and the leading indication for pediatric liver transplantation worldwide. The disease is caused by a progressive inflammatory and fibrosing obliteration of the extrahepatic bile ducts. Although the cause of this obstruction is largely unknown, patient-based studies have identified environmental and genetic factors that may interact and orchestrate disease pathogenesis. Chief among these factors are infectious and immunologic processes. While infectious agents have varied in different patient populations, studies of liver specimens at different phases of disease point to a pro-inflammatory commitment of lymphocytes at the time of diagnosis, and to their potential role in regulating bile duct obstruction. A review of these studies is the focus of this article.

Pathogenesis of extrahepatic bile duct atresia (EHBA): comprehension from a surgical point of view.

INTRODUCTION: The aim of the study is to establish a complete comprehension of the pathogenesis of Biliary Atresia, and to explain both the variable and redundant pathomorphological, as well as, histological findings. MATERIALS AND METHODS: The pathomorphological and histological findings in 223 patients with histologically evident EHBA were recorded retrospectively (72 patients) or prospectively (151 patients), according to a projected ascending study. These findings were compared with histological findings in human and rat embryos. RESULTS: 1) The pathomorphological findings recorded in patients with EHBA were also found in stages of normal embryogenesis of the bile duct system in human and rat embryos. 2) Each histological finding in Biliary Atresia corresponds to a finding in an interrupted stage of the normal development in human and rat embryos. 3) The findings in patients and embryos can be explained completely by a disturbed intrinsic epithelium/mesoderm interaction. 4) Some findings in Biliary Atresia cannot be explained easily by the assumption of an extrinsic factor. CONCLUSION: There is no finding in Biliary Atresia which cannot be completely explained as the result of an intrinsic developmental error, probably due to disturbances or interruption of epithelium/mesoderm interaction during embryogenesis.

Isolation and culture of biliary epithelial cells from bile duct remnants of patients with biliary atresia.

Biliary atresia(BA), the most common cause of obstructive jaundice in infancy, has been considered to be a result of progressive destruction of the bile ducts through a necroinflammatory process. Many immunohistochemical studies of BA remnant have been done, but it has not been shown that biliary epithelial cells (BECs) can be cultured from BA remnant. For this study, we obtained bile duct remnants from three patients with biliary atresia (one male, two females) who received Kasai's operation from 2002 to 2003. The successive cultivation rate of BECs from explants was 100% (3/3 patients). Culture of BECs on collagen gel was possible up to at least four passages. Under a phase-contrast microscope, primary and passed cultured cells on collagen gel showed a cobblestone-like spread in 2 weeks. The BECs had immunoreactivity to anti-human cytokeratin 7 antibody. In this study, we proved that BECs in the remnants of BA could be cultured, and defined the maturation of biliary epithelial cells of BA by immunocytochemistry with anti-human cytokeratin 7 antibody. In conclusion, BECs in BA remnant are "alive", and their proliferation activity can be maintained.

Biliary atresia due to delayed maturation of the gut hormones' system?--Introducing a new treatment modality.

BACKGROUND: Congenital biliary atresia is suspected to originate from prenatal biliary duct inflammation of unknown etiology. OBJECTIVE: Based on clinical grounds, we aimed to establish a hypothesis on the primary cause of inflammation, and to suggest a causal treatment modality. CASE REPORT: History. A 28 years old Turkish woman had lost her first child aged two years from congenital biliary atresia (parents second degree cousins). After a miscarriage, in her otherwise uneventful third pregnancy sonography at 34 wks revealed echogenic material in the fetal gallbladder. Nine days later the gallbladder was completely filled with sludge. Chemical inflammation was suspected, and birth was induced at 36+3 weeks in order to allow for surgical flushing of the bile duct. Neonatal clinical chemistry was insuspicious. There was no spontaneous resolution of the sludge within the first 24 hours of life. A trial of medical treatment with intermittent i.v. secretin (0.03 CU/kg/h) and i.v. coeruletid (60 ng/kg/h) was started. Within 24 hours, sludge had resolved. CONCLUSIONS: We hypothesize that dysmaturation may lead to insufficient induction/production/activity of intrinsic gut hormones resulting in prenatally impaired bile flow, or even inspissated bile. Familial occurrence suggests a genetic defect. Exogenous hormone therapy might be an appropriate treatment modality.

Induction of bile ducts in embryonic liver by mesenchyme: a new perspective for the treatment of biliary atresia?

Presently only those forms of Extrahepatic Biliary Atresia (EHBA) with minimal or no intrahepatic manifestations can be treated successfully by extensive hepatoportoenterostomy. Intraoperative macro- and microscopic observations show that the typical pathogenetic manifestations in EHBA are most prominent at the porta hepatis. We therefore postulate that EHBA is the result of a defective embryonic development of the porta hepatis. In rat embryos hepatic bile duct formation is initiated at the porta hepatis and in this context mesenchyme from the periportal region seems to play a major inductive role. In order to demonstrate the role of invading periportal mesenchyme for the process of bile duct rudiment formation we established an organ culture model of the embryonic porta hepatis by recombining periportal mesenchyme with peripheral liver fragments from 15 days old rat embryos (Carnegie Stage 21). The degree of mesenchyme invasion as well as the formation of mesenchyme-surrounded liver cell clusters, rosettes or vesicles (bile duct rudiments) were assessed. Mesenchyme from the porta hepatis invaded the peripheral liver fragments and induced the formation of mesenchyme-surrounded liver cell clusters and rosettes with the beginning of lumen formation. Kidney mesenchyme recombined with liver fragments as a mesenchymal alternative showed almost the same effect, lung mesenchyme showed only a very weak inductive effect. To assess the effect of a diffusible factor versus direct cell contact, a millipore filter with and without paraffin coating was interposed between mesenchyme containing tissue and peripheral liver tissue fragments. Without direct cell contact to mesenchyme no hepatoblast cluster or rosette formation could be observed. Comparing this result to the normal development of the liver in rats our investigations suggest that the embryogenesis of the porta hepatis is probably defined by the following two developmental steps: First, differentiation of the intrahepatic bile duct system which is induced by invading mesenchyme originating from the extrahepatic periportal region and realized by epithelium mesenchyme interaction. Second, fusion of extra- and intrahepatic bile duct systems at the level of the later porta hepatis. Disturbances of this complex process can possibly lead to biliary atresia. Further investigations regarding details of the role of the mesenchyme, its inductive factors and the kidney mesenchyme's inductive potential in liver development may provide a new perspective for future treatment of biliary atresia.

Computer-generated three-dimensional morphology of the hepatic hilar bile ducts in biliary atresia.

BACKGROUND/PURPOSE: In biliary atresia (BA), although the intrahepatic bile ducts are reported to appear in the fetal configuration in about 20% to 60% of cases, information about the 3-dimensional (3-D) morphology of the hilar biliary structures is limited. The authors, therefore, have applied the technique of computer-generated 3-D reconstruction, to study the morphology of the hilar biliary structures in patients who have undergone biliary decompression. METHODS: Computer-generated 3-D reconstructions were performed from serial sections of the hepatic hilum of 4 BA patients and compared with those obtained from a 3-day old infant who had no apparent biliary disease but died of congenital diaphragmatic hernia (CDH) and with normal human fetal ductal plate at 11 weeks of gestation. RESULTS: In all 4 BA patients, the hilar bile ducts strongly resembled the ductal plate structures of the fetus rather than the bile ducts of the CDH infant. This leads the authors to suggest that these abnormal biliary structures are the result of improper ductal plate remodeling at the hepatic hilum. In 3 of the BA patients there were some tubular bile ducts that probably are the result of delayed and abnormal attempt at ductal plate remodeling.

Assay of gamma-glutamyl transpeptidase activity in amniotic fluid offers a possible prenatal diagnosis of biliary atresia in the rat model.

Muller et al. analysed gamma-glutamyl transpeptidase (GGTP) activity in the amniotic fluid of more than 2000 pregnant women for a prenatal diagnosis. They reported that at 18-19 weeks' gestation, two fetuses associated with lower amniotic fluid GGTP levels were diagnosed after birth as having biliary atresia (BA). If low GGTP values correlate closely with BA, chemical assay of amniotic fluid GGTP could possibly be used in the prenatal diagnosis of BA. A fetal model of cholestasis in the rat was created by the administration of the toxic cytopharmacological agent phalloidin on day 15 of gestation, after which amniotic fluid was aspirated and analysed for GGTP. Fetal liver specimens were examined histopathologically. In the normal rats, amniotic fluid GGTP values rose rapidly after 18 days 8 h, reaching a maximum value at 19 days of gestation. Significantly lower GGTP values were observed in the cholestasis models between 18 days 16 h and 19 days 16 h of gestation (P < 0.05). Our data corroborate Muller et al.'s suggestion that fetuses with cholestasis might demonstrate lower GGTP values in their amniotic fluid at a given stage of gestation. Prenatal diagnosis of BA using the amniotic fluid GGTP assay therefore has considerable potential.

Is it possible to differentiate between choledochal cyst and congenital biliary atresia (type I cyst) by antenatal ultrasonography?

Both choledochal cyst and congenital biliary atresia (type I cyst) may share the same ultrasonographic pattern. We report 2 cases which were shown to have cystic structures on the upper abdomen by antenatal ultrasonography. The size of the choledochal cyst found at 24 weeks' gestation increased steadily as gestational age advanced. But the size of the cyst in congenital biliary atresia found at 29 weeks' gestation remained unchanged throughout the remaining pregnancy. Cyst enlargement, therefore, may suggest the possibility of a choledochal cyst.

[Prenatal diagnosis of biliary atresia associated with choledochal cyst]. / Diagnóstico prenatal de atresia biliar asociada a quiste de colédoco.

We report a case of biliary atresia promptly detected by its association with a choledochal cyst, prenatally diagnosed at 20 weeks' gestation. The baby was operated at 14 days of life. A choledochal cyst was found and fibrosis of the extrahepatic bile ducts was also noted. So, excision of the choledochal cyst and a Roux-en-Y porto-jejunostomy was done. Nine months later, despite an appropriate biliary drainage, echographic and histological changes compatible with liver cirrhosis have been detected. Including this one, six cases have been reported.

Bile ductule formation in fetal, neonatal, and infant livers compared with extrahepatic biliary atresia.

The cell of origin of intrahepatic bile ducts during fetal development remains a subject of controversy, although there has been recent evidence that they form from hepatocytes. However, the origin of neoductules and ducts in the setting of liver disease has not been extensively investigated in humans. Using anticytokeratins characteristic of hepatocytes and bile ducts, we repeated earlier studies of fetal development to compare ductule formation in normal developing and newborn livers with the ductules formed during extrahepatic biliary atresia. We utilized an antibody to proliferating cell nuclear antigen (PCNA) staining to determine which cells were in active DNA synthesis (S phase) during fetal development and liver disease progression. The results indicated that hepatocytes undergo a phenotypic switch (metaplasia) to form ductular cells during fetal development. There was no ductular cell replication in the fetal livers. In contrast, both bile ductular metaplasia and proliferation were observed in biliary atresia. Therefore, both a limiting plate phenotypic switch to ductules and replication of ductular cells play a role in the increase in the ductules seen in the progression to biliary cirrhosis. Bile ductular proliferation in biliary atresia, however, was less than that seen in hepatocytes, whereas the number of bile ductules increased and the relative proportion of hepatocytes diminished as the accompanying periductular fibrosis progressed to cirrhosis.

Distortion in TGF beta 1 peptide immunolocalization in biliary atresia: comparison with the normal pattern in the developing human intrahepatic bile duct system.

Biliary atresia is an important cause of neonatal obstructive jaundice in which there is inflammation, sclerosis and eventual obliteration of the bile duct system. Its onset may be antenatal, affecting the normal development of the biliary system. The intrahepatic biliary system is derived from the ductal plate, a sheath of cuboidal epithelium that appears at the hepatocyte-mesenchymal junction around the portal vein branches at 6 weeks gestation. This epithelial structure is moulded into a network of tubular bile ducts by the proliferating mesenchyme. Certain portions of the ductal plate are selected to become definitive bile ducts, while redundant biliary epithelium is deleted. The molecular dynamics controlling the intra-uterine development of the biliary system in humans are not yet clearly understood. Transforming growth factor-beta 1 is a cytokine that stimulates mesenchymal proliferation and inhibits epithelial growth, and has been shown to be important in organogenesis. In the present study, the pattern of TGF beta 1 peptide immunolocalization was investigated with the aid of computerized image analysis, in normal human bile duct development and in biliary atresia. TGF beta 1 peptide was detected within hepatocytes and ductal plate epithelium from 7 weeks gestation; increased TGF beta 1 immunoreactivity was present within the epithelium of developing bile ducts at 13 weeks gestation, and apical polarization of the cytokine was observed from 16 weeks gestation. In biliary atresia, the TGF beta 1 immunoreactivity pattern within the bile duct structures at the porta hepatis and within intrahepatic portal tracts resembled that of the primitive ductal plate, and there was no significant apical polarization. This may indicate a developmental arrest in the normal ductal plate remodelling process in biliary atresia, and suggests an underlying epithelial-mesenchymal interactive disorder.