Biliary atresia

Biliary atresia and congenital disorders of the extrahepatic bile ducts

Biliary atresia (BA) and choledochal cysts are diseases of the intrahepatic and extrahepatic biliary tree. While their exact etiopathogeneses are not known, they should be treated promptly due to the potential for irreversible parenchymal liver disease. A diagnosis of BA may be easy or complicated, but should not be delayed. BA is always treated surgically, and performing the surgery before the age of 2 mo greatly increases its effectiveness and extends the time until the need for liver transplantation arises. While the more common types of choledochal cysts require surgical treatment, some can be treated with endoscopic retrograde cholangiopancreatography. Choledochal cysts may cause recurrent cholangitis and the potential for malignancy should not be ignored.

Current and emerging adjuvant therapies in biliary atresia

Following Kasai hepatic portoenterostomy (HPE), most patients with biliary atresia will eventually require liver transplantation due to progressive cirrhosis and liver failure. Preventing liver transplantation, or even delaying eventual liver transplantation, is the key to improving long-term outcomes. This review first examines the commonly used adjuvant therapies in post-HPE biliary atresia and the strength of the evidence supporting these therapies. Next, it examines the evolving frontiers of management through a comprehensive evaluation of both recently completed and ongoing clinical trials in biliary atresia. Promising therapies used in other cholestatic liver diseases with potential benefit in biliary atresia are discussed. Improving post-HPE management is critical to prevent complications, delay liver transplantation, and ultimately improve the long-term survival of patients with biliary atresia.

Variability in age at Kasai portoenterostomy for biliary atresia across US children's hospitals

BACKGROUND/PURPOSE

The purpose of this study was to assess variability in age at Kasai portoenterostomy (KP) in infants with biliary atresia (BA) across children's hospitals in the United States.

STUDY DESIGN

A multi-institutional retrospective study was performed examining infants with BA undergoing KP within 6 months of birth from 2016-2019, utilizing the Pediatric Health Information System (PHIS). Multivariable negative binomial mixed effects regression was performed for age at KP, and inter-hospital variability was examined.

RESULTS

Across 46 hospitals, 470 infants with BA underwent KP at a median age of 57 days (IQR 42-72), with 212 (45.1%) undergoing KP at ≥60 days of age. There was significant inter-hospital variability in age at KP ranging from 38 days (95% CI: 31d, 47d) to 76 days (95% CI: 63d, 91d) (p<0.0001). Factors associated with later KP were black or African-American race, urgent/emergent admission, and treatment at a hospital in the Pacific-West region. Predictors of earlier KP included later year, history of neonatal comorbidity, and admission to an intensive care service (all p<0.05).

CONCLUSION

There is significant variability in the age at KP in infants with BA across children's hospitals in the United States.

TYPE OF STUDY

Retrospective study.

LEVEL OF EVIDENCE

III.

Extrahepatic cholangiocyte obstruction is mediated by decreased glutathione, Wnt and Notch signaling pathways in a toxic model of biliary atresia

Biliary atresia is a neonatal liver disease with extrahepatic bile duct obstruction and progressive liver fibrosis. The etiology and pathogenesis of the disease are unknown. We previously identified a plant toxin, biliatresone, responsible for biliary atresia in naturally-occurring animal models, that causes cholangiocyte destruction in in-vitro models. Decreases in reduced glutathione (GSH) mimic the effects of biliatresone, and agents that replenish cellular GSH ameliorate the effects of the toxin. The goals of this study were to define signaling pathways downstream of biliatresone that lead to cholangiocyte destruction and to determine their relationship to GSH. Using cholangiocyte culture and 3D cholangiocyte spheroid cultures, we found that biliatresone and decreases in GSH upregulated RhoU/Wrch1, a Wnt signaling family member, which then mediated an increase in Hey2 in the NOTCH signaling pathway, causing downregulation of the transcription factor Sox17. When these genes were up- or down-regulated, the biliatresone effect on spheroids was phenocopied, resulting in lumen obstruction. Biopsies of patients with biliary atresia demonstrated increased RhoU/Wrch1 and Hey2 expression in cholangiocytes. We present a novel pathway of cholangiocyte injury in a model of biliary atresia, which is relevant to human BA and may suggest potential future therapeutics.

TGF-β Signaling Plays a Pivotal Role During Developmental Biliary Atresia in Sea Lamprey (Petromyzon marinus)

Biliary atresia (BA) is a rare neonatal disease with unknown causes. Approximately 10% of BA cases develop in utero with other congenital defects that span a large spectrum of disease variations, including degeneration of the gall bladder and bile duct as well as malformation of the liver, intestines, and kidneys. Similar developmental alterations are manifested in a unique animal model, the sea lamprey (Petromyzon marinus), in which BA occurs naturally during metamorphosis. With the likelihood of conserved developmental mechanisms underlying organogenesis and degeneration, lamprey developmental BA may be a useful model to infer mechanisms underlying human embryonic BA. We reasoned that hepatobiliary transcriptomes regulate the transition between landmark stages of BA. Therefore, we examined sea lamprey hepatobiliary transcriptomes at four stages (M0, metamorphic stage 0 or larval stage, no BA; M2, metamorphic stage 2, onset of BA; M5, metamorphic stage 5, BA, and heightened hepatocyte proliferation and reorganization; and JV, juvenile, completion of BA) using messenger RNA sequencing and Kyoto Encyclopedia of Genes and Genomes pathway analyses. We found gene-expression patterns associated with the transition between these stages. In particular, transforming growth factor β (TGF-β), hedgehog, phosphatidylinositol-4,5-bisphosphate 3-kinase-Akt, Wnt, and mitogen-activated protein kinase pathways were involved during biliary degeneration. Furthermore, disrupting the TGF-β signaling pathway with antagonist or small interfering RNA treatments at the onset of BA delayed gall bladder and bile duct degeneration. Conclusion: Distinctive gene-expression patterns are associated with the degeneration of the biliary system during developmental BA. In addition, disrupting TGF-β signaling pathway at the onset of BA delayed biliary degeneration.

Synthesis and Structure-Activity Relationship Study of Biliatresone, a Plant Isoflavonoid That Causes Biliary Atresia

We report the first synthesis of the plant isoflavonoid biliatresone. The convergent synthesis has been applied to the synthesis of several analogs, which have facilitated the first structure-activity relationship study for this environmental toxin that, on ingestion, recapitulates the phenotype of biliary atresia.

Pediatric cholangiopathies: diseases of the gallbladder and biliary tract

Pediatric gallbladder and bile duct disease encompasses a broad spectrum of processes, from congenital to developmental to neoplastic. We describe normal pediatric biliary anatomy and summarize the most common pathologic entities, with a focus on non-invasive imaging techniques and findings. Ultrasound is the first-line imaging modality in children with suspected biliary pathology based on its widespread availability, cost effectiveness, and lack of ionizing radiation. MRI and MRCP are often used for further evaluation in cases of diagnostic uncertainty and for surgical planning.

The toxin biliatresone causes mouse extrahepatic cholangiocyte damage and fibrosis through decreased glutathione and SOX17

Biliary atresia, the most common indication for pediatric liver transplantation, is a fibrotic disease of unknown etiology affecting the extrahepatic bile ducts of newborns. The recently described toxin biliatresone causes lumen obstruction in mouse cholangiocyte spheroids and represents a new model of biliary atresia. The goal of this study was to determine the cellular changes caused by biliatresone in mammalian cells that ultimately lead to biliary atresia and extrahepatic fibrosis. We treated mouse cholangiocytes in three-dimensional (3D) spheroid culture and neonatal extrahepatic duct explants with biliatresone and compounds that regulate glutathione (GSH). We examined the effects of biliatresone on SOX17 levels and determined the effects of Sox17 knockdown on cholangiocytes in 3D culture. We found that biliatresone caused disruption of cholangiocyte apical polarity and loss of monolayer integrity. Spheroids treated with biliatresone had increased permeability as shown by rhodamine efflux within 5 hours compared with untreated spheroids, which retained rhodamine for longer than 12 hours. Neonatal bile duct explants treated with the toxin showed lumen obstruction with increased subepithelial staining for α-smooth muscle actin and collagen, consistent with fibrosis. Biliatresone caused a rapid and transient decrease in GSH, which was both necessary and sufficient to mediate its effects in cholangiocyte spheroid and bile duct explant systems. It also caused a significant decrease in cholangiocyte levels of SOX17, and Sox17 knockdown in cholangiocyte spheroids mimicked the effects of biliatresone.

CONCLUSION

Biliatresone decreases GSH and SOX17 in mouse cholangiocytes. In 3D cell systems, this leads to cholangiocyte monolayer damage and increased permeability; in extrahepatic bile duct explants, it leads to disruption of the extrahepatic biliary tree and subepithelial fibrosis. This mechanism may be important in understanding human biliary atresia. (Hepatology 2016;64:880-893).

Glutathione antioxidant pathway activity and reserve determine toxicity and specificity of the biliary toxin biliatresone in zebrafish

Biliatresone is an electrophilic isoflavone isolated from Dysphania species plants that has been causatively linked to naturally occurring outbreaks of a biliary atresia (BA)-like disease in livestock. Biliatresone has selective toxicity for extrahepatic cholangiocytes (EHCs) in zebrafish larvae. To better understand its mechanism of toxicity, we performed transcriptional profiling of liver cells isolated from zebrafish larvae at the earliest stage of biliatresone-mediated biliary injury, with subsequent comparison of biliary and hepatocyte gene expression profiles. Transcripts encoded by genes involved in redox stress response, particularly those involved in glutathione (GSH) metabolism, were among the most prominently up-regulated in both cholangiocytes and hepatocytes of biliatresone-treated larvae. Consistent with these findings, hepatic GSH was depleted at the onset of biliary injury, and in situ mapping of the hepatic GSH redox potential using a redox-sensitive green fluorescent protein biosensor showed that it was significantly more oxidized in EHCs both before and after treatment with biliatresone. Pharmacological and genetic manipulation of GSH redox homeostasis confirmed the importance of GSH in modulating biliatresone-induced injury given that GSH depletion sensitized both EHCs and the otherwise resistant intrahepatic cholangiocytes to the toxin, whereas replenishing GSH level by N-acetylcysteine administration or activation of nuclear factor erythroid 2-like 2 (Nrf2), a transcriptional regulator of GSH synthesis, inhibited EHC injury.

CONCLUSION

These findings strongly support redox stress as a critical contributing factor in biliatresone-induced cholangiocyte injury, and suggest that variations in intrinsic stress responses underlie the susceptibility profile. Insufficient antioxidant capacity of EHCs may be critical to early pathogenesis of human BA. (Hepatology 2016;64:894-907).

Identification of a plant isoflavonoid that causes biliary atresia

Biliary atresia (BA) is a rapidly progressive and destructive fibrotic disorder of unknown etiology affecting the extrahepatic biliary tree of neonates. Epidemiological studies suggest that an environmental factor, such as a virus or toxin, is the cause of the disease, although none have been definitively established. Several naturally occurring outbreaks of BA in Australian livestock have been associated with the ingestion of unusual plants by pregnant animals during drought conditions. We used a biliary secretion assay in zebrafish to isolate a previously undescribed isoflavonoid, biliatresone, from Dysphania species implicated in a recent BA outbreak. This compound caused selective destruction of the extrahepatic, but not intrahepatic, biliary system of larval zebrafish. A mutation that enhanced biliatresone toxicity mapped to a region of the zebrafish genome that has conserved synteny with an established human BA susceptibility locus. The toxin also caused loss of cilia in neonatal mouse extrahepatic cholangiocytes in culture and disrupted cell polarity and monolayer integrity in cholangiocyte spheroids. Together, these findings provide direct evidence that BA could be initiated by perinatal exposure to an environmental toxin.

Biliary Atresia Is Associated With Hypertension

OBJECTIVES

The improved survival of pediatric liver transplant recipients is accompanied by an increase in long-term comorbidities. A recently highlighted concern, hypertension, is associated with chronic kidney disease (CKD) in this population and can result in other target-organ damage during childhood. The prevalence of hypertension in pediatric liver transplantation is imprecisely known. In addition, individual etiologies of liver failure may convey different risks of hypertension. We sought to study the effect of liver transplantation on the prevalence of hypertension and CKD in patients with biliary atresia (BA).

METHODS

We conducted a retrospective chart review of 160 patients with BA followed at the Mount Sinai Medical Center, New York, from 1987 to 2012. Data were accumulated from the initial and subsequent visits at approximately 6 months, 1, 3, 5, 10, and 15 years of age. Hypertension was defined as systolic blood pressure >95th percentile for age, sex, height, and/or use of antihypertensive medication. Renal function was examined over time. Data were stratified by liver transplantation status at the time of visit.

RESULTS

A high prevalence of hypertension was observed from the initial visit through age 10, independent of transplant status (transplanted: 48% initial visit and 13% after 10 years vs nontransplanted: 55% initial visit and 17% after 10 years [P = ns for transplant status]). Mean estimated glomerular filtration rate (eGFR) was lower among liver transplant patients as compared with nontransplant patients and declined posttransplant. The incidence of CKD was higher among transplant patients.

CONCLUSIONS

Hypertension is common among children with BA, independent of liver transplant status. Transplant patients had significantly reduced renal function, which continued to decline over time. Hypertension was not associated with reduced eGFR.

Gender-based differences in pediatric nuclear medicine

Gender-based differences commonly encountered in pediatric nuclear medicine reflect both basic embryologic differences of the sexes, which are evident from infancy, and evolving physiological changes due to gender, which occur as the pediatric patient grows, undergoes puberty, and matures to adulthood. It is important for a nuclear medicine physician or radiologist to know both the gender and the age of a patient when interpreting her or his studies. It is also important that the reading physician be familiar with the normally evolving physiological changes that are specific for that patient's stage of development. It is particularly important that the reading physician consider such changes when comparing serial studies of the patient that are acquired during the patient's transitions through her or his different significant stages of development. Many pediatric nuclear medicine imaging protocols are modifications or adaptations of the protocols for adult imaging. Physicians reading pediatric studies must routinely incorporate knowledge on age and gender that is relevant to the patient for any given study. The age-defined gender-based subtleties of potential findings in pediatric nuclear medicine studies are often underrecognized. However, they are often of interest and at times important in the workup of both benign entities and pathologic processes of the pediatric patient.

The use of Yes-associated protein expression in the diagnosis of persistent neonatal cholestatic liver disease

Although physiologic jaundice of neonates is common, persistent neonatal cholestasis is life-threatening and has multiple etiologies. Among these etiologies, biliary atresia (BA) requires rapid diagnosis and treatment. In diagnosing BA, the surgical pathologist must recognize subtle histologic changes, often with only a small core liver biopsy. To aid in the differential diagnosis of neonatal cholestasis, we investigated Yes-associated protein (YAP), a regulator of organ size and bile duct development. We examined whether a YAP immunostain can highlight emerging hepatobiliary epithelium in BA (n = 28) versus other causes of persistent cholestasis (non-BA; n = 15) and thus serve as a useful diagnostic marker in persistent neonatal jaundice. We show significantly (P < .01) more high-grade (<2) fibrosis and ductular proliferation among BA versus non-BA cases. Likewise, there was significantly more high-grade (2-3/3) cytoplasmic and nuclear YAP staining in BA (97% and 89%) versus non-BA (20% and 13%). High-grade nuclear YAP staining was both sensitive (88%) and specific (87%) for the diagnosis of BA. In contrast to neonatal cholestasis, the differences in YAP localization in cholestatic/obstructed versus nonobstructed adult livers were not significant. Lastly, we found that pharmacologic inhibition of the YAP complex in both cholangiocyte and cholangiocarcinoma cell lines blocked compensatory bile duct proliferation, an early marker of BA that requires nuclear YAP expression, in a time- and dose-dependent manner. In summary, we show that YAP expression modulates both bile duct proliferation and liver damage/fibrosis while acting as a sensitive and specific marker in the differential diagnosis of persistent neonatal cholestasis.

Zebrafish models of human liver development and disease

The liver performs a large number of essential synthetic and regulatory functions that are acquired during fetal development and persist throughout life. Their disruption underlies a diverse group of heritable and acquired diseases that affect both pediatric and adult patients. Although experimental analyses used to study liver development and disease are typically performed in cell culture models or rodents, the zebrafish is increasingly used to complement discoveries made in these systems. Forward and reverse genetic analyses over the past two decades have shown that the molecular program for liver development is largely conserved between zebrafish and mammals, and that the zebrafish can be used to model heritable human liver disorders. Recent work has demonstrated that zebrafish can also be used to study the mechanistic basis of acquired liver diseases. Here, we provide a comprehensive summary of how the zebrafish has contributed to our understanding of human liver development and disease.

Extrahepatic cholangiocyte cilia are abnormal in biliary atresia

OBJECTIVES

Biliary atresia (BA) is a rapidly progressive form of biliary fibrosis affecting neonates. We previously reported that primary cilia on the intrahepatic cholangiocytes of patients with both syndromic and nonsyndromic BA were structurally abnormal. Our objective was to determine whether extrahepatic cholangiocytes in human biliary atresia, intrahepatic and extrahepatic cholangiocytes of rhesus rotavirus (RRV)-infected neonatal mice, and RRV-infected primary neonatal extrahepatic cholangiocytes also demonstrate ciliary abnormalities.

METHODS

The livers of neonatal BALB/c mice injected with RRV that developed jaundice, human extrahepatic bile duct samples obtained at time of hepatoportoenterostomy, and RRV-infected primary neonatal cholangiocytes were stained with antibodies against acetylated α tubulin to identify primary cilia.

RESULTS

Extrahepatic cholangiocytes from RRV-treated mice demonstrated minimal loss of primary cilia at day 3 but almost complete loss at day 8 and partial loss at day 12. No changes were seen in mouse intrahepatic bile ducts at any of the time points. In the human BA samples, primary cilia were almost completely absent from extrahepatic duct cholangiocytes. There were, however, abundant cilia in the peribiliary glands adjacent to extrahepatic ducts in the BA sample. Cilia in RRV-infected primary neonatal cholangiocytes were significantly decreased compared with controls.

CONCLUSIONS

Primary cilia are selectively lost from neonatal extrahepatic but not intrahepatic cholangiocytes after RRV infection in BALB/c mice. The cilia are also decreased in RRV-infected primary cholangiocytes and the extrahepatic ducts from human patients with BA. This suggests that ciliary abnormalities are part of the pathophysiology of BA.

Interferon-gamma directly mediates developmental biliary defects

Biliary atresia (BA) is the most common identifiable hepatobiliary disease affecting infants, in which there are defects in intra- and extrahepatic bile ducts and progressive fibrosis. Activation of interferon-gamma (IFNγ) appears to be critical in both patients with BA and in rodent models of BA. We have recently reported a zebrafish model of biliary disease that shares features with BA, in which inhibition of DNA methylation leads to intrahepatic biliary defects and activation of IFNγ target genes. Here we report that ifng genes are hypomethylated and upregulated in zebrafish larvae treated with azacytidine (azaC), an inhibitor of DNA methylation. Injection of IFNγ protein into developing zebrafish larvae leads to biliary defects, suggesting that activation of the IFNγ pathway is sufficient to cause developmental biliary defects. These defects are associated with decreased cholangiocyte proliferation and with a decrease in the expression of vhnf1 (hnf1b, tcf2), which encodes a homeodomain protein with previously reported roles in biliary development in multiple models. These results support an importance of IFNγ in mediating biliary defects, and also demonstrate the feasibility of direct injection of intact protein into developing zebrafish larvae.

Rargb regulates organ laterality in a zebrafish model of right atrial isomerism

Developmental signals determine organ morphology and position during embryogenesis. To discover novel modifiers of liver development, we performed a chemical genetic screen in zebrafish and identified retinoic acid as a positive regulator of hepatogenesis. Knockdown of the four RA receptors revealed that all receptors affect liver formation, however specific receptors exert differential effects. Rargb knockdown results in bilateral livers but does not impact organ size, revealing a unique role for Rargb in conferring left-right positional information. Bilateral populations of hepatoblasts are detectable in rargb morphants, indicating Rargb acts during hepatic specification to position the liver, and primitive endoderm is competent to form liver on both sides. Hearts remain at the midline and gut looping is perturbed in rargb morphants, suggesting Rargb affects lateral plate mesoderm migration. Overexpression of Bmp during somitogenesis similarly results in bilateral livers and midline hearts, and inhibition of Bmp signaling rescues the rargb morphant phenotype, indicating Rargb functions upstream of Bmp to regulate organ sidedness. Loss of rargb causes biliary and organ laterality defects as well as asplenia, paralleling symptoms of the human condition right atrial isomerism. Our findings uncover a novel role for RA in regulating organ laterality and provide an animal model of one form of human heterotaxia.

Transient elastography for predicting esophageal/gastric varices in children with biliary atresia

Background

Transient elastography (TE) is an innovative, noninvasive technique to assess liver fibrosis by measuring liver stiffness in patients with chronic liver diseases. The purpose of this study has been to explore the accuracy of TE and clinical parameters in predicting the presence of esophageal/gastric varices in children with biliary atresia (BA) following portoenterostomy.

Methods

Patients with BA status post portoenterostomy and normal children were recruited. Splenomegaly and presence of EV/GV were determined by physical examination and endoscopy, respectively. Aspartate transaminase to platelet ratio index (APRI) was used as a serum fibrosis marker. TE was performed by using FibroScan. Data was expressed as mean ± SD.

Results

Seventy-three BA patients (male:female = 32:41; age 9.11 ± 5.64 years) and 50 normal controls (male:female = 19:31; age 11.00 ± 3.31 years) were enrolled. The liver stiffness score of BA patients was significantly higher than that of normal controls (27.37 ± 22.48 and 4.69 ± 1.03 kPa; p < 0.001). Patients with EV/GV had significantly higher liver stiffness score and APRI than those without EV/GV. As for EV/GV diagnosis, the areas under the receiver operating characteristic curve were 0.89 (95% CI 0.80 to 0.98) for TE and 0.87 (95% CI 0.78 to 0.96) for APRI, respectively. The sensitivity (and specificity) of TE (using a cut-off value of 12.7 kPa) and APRI (using a cut-off value of 1.92) in predicting EV/GV were 84% (77%) and 84% (83%), respectively, whereas the sensitivity (and specificity) of splenomegaly in predicting EV/GV were 92% (85%).

Conclusions

Transient elastography is a useful tool for predicting the presence of EV/GV. In addition, basic physical examination, routine biochemical and hematological tests, are still worthwhile and correlate well with the presence of EV/GV in patients with BA post portoenterostomy.

Design and validation of the biliary atresia research consortium histologic assessment system for cholestasis in infancy

BACKGROUND & AIMS

Pathologists participating in the National Institutes of Health-sponsored Biliary Atresia Research Consortium (BARC) developed and then evaluated a standardized system for histologic reporting of liver biopsies from infants with cholestasis.

METHODS

A set of 97 anonymous liver biopsy samples was sent to 10 pathologists at BARC centers. A semiquantitative scoring system that had 16 histologic features was developed and then used by the pathologists, who had no knowledge of clinical history, imaging results, or laboratory data. Interobserver agreement was evaluated statistically. Agreement on scoring of each feature and on the pathologists' diagnosis, compared with the final clinical diagnosis, was evaluated by using weighted kappa statistics.

RESULTS

There was moderate to substantial interobserver agreement in identification of bile plugs in ducts, giant-cell transformation, extramedullary hematopoiesis, and bile duct proliferation. The pathologists' diagnosis of obstruction in clinically proven cases of biliary atresia (BA) ranged from 79%-98%, with a positive predictive value of 90.7%. Histologic features that best predicted BA, on the basis of logistic regression, included bile duct proliferation, portal fibrosis, and absence of sinusoidal fibrosis (each P<.0001).

CONCLUSIONS

The BARC histologic assessment system identified features of liver biopsies from cholestatic infants, with good interobserver agreement, that might be used in diagnosis and determination of prognosis. The system diagnosed BA with a high level of sensitivity and identified infants with biliary obstruction with reasonable interobserver agreement. However, distinguishing between BA and disorders such as total parenteral nutrition-associated liver disease and alpha(1)-antitrypsin deficiency is not possible without adequate clinical information.

DNA hypomethylation causes bile duct defects in zebrafish and is a distinguishing feature of infantile biliary atresia

Infantile cholestatic disorders arise in the context of progressively developing intrahepatic bile ducts. Biliary atresia (BA), a progressive fibroinflammatory disorder of extra- and intrahepatic bile ducts, is the most common identifiable cause of infantile cholestasis and the leading indication for liver transplantation in children. The etiology of BA is unclear, and although there is some evidence for viral, toxic, and complex genetic causes, the exclusive occurrence of BA during a period of biliary growth and remodeling suggests an importance of developmental factors. Interestingly, interferon-γ (IFN-γ) signaling is activated in patients and in the frequently utilized rhesus rotavirus mouse model of BA, and is thought to play a key mechanistic role. Here we demonstrate intrahepatic biliary defects and up-regulated hepatic expression of IFN-γ pathway genes caused by genetic or pharmacological inhibition of DNA methylation in zebrafish larvae. Biliary defects elicited by inhibition of DNA methylation were reversed by treatment with glucocorticoid, suggesting that the activation of inflammatory pathways was critical. DNA methylation was significantly reduced in bile duct cells from BA patients compared to patients with other infantile cholestatic disorders, thereby establishing a possible etiologic link between decreased DNA methylation, activation of IFN-γ signaling, and biliary defects in patients.

CONCLUSION

Inhibition of DNA methylation leads to biliary defects and activation of IFN-γ-responsive genes, thus sharing features with BA, which we determine to be associated with DNA hypomethylation. We propose epigenetic activation of IFN-γ signaling as a common etiologic mechanism of intrahepatic bile duct defects in BA.

Elevated serum macrophage migration inhibitory factor levels in post-operative biliary atresia

OBJECTIVE

Biliary atresia (BA) is one of the most common causes of neonatal cholestasis. Macrophage migration inhibitory factor (MIF) is an important mediator of inflammation and immune response in various diseases. The objective of this study was to examine the possible roles of MIF in BA.

METHODS

Forty-eight BA paediatric patients who had undergone a Kasai operation and 22 healthy children were recruited. The mean ages of the patients and controls were 8.47 +/- 0.74 and 7.64 +/- 0.41 years, respectively. The patients were categorised into two groups according to their serum levels of total bilirubin (TB) (TB < 2 mg/dL; no jaundice, and TB >/= 2 mg/dL; persistent jaundice). The serum MIF levels were determined using commercially available enzyme-linked immunosorbent assay.

RESULTS

The mean serum MIF level of the BA children was higher than that of healthy controls (0.43 +/- 0.04 ng/mL [corrected] vs. 0.27 +/- 0.02 ng/mL; [corrected] p < 0.001). However, there was no difference in serum MIF levels between BA patients with jaundice and those without jaundice. Further analysis revealed that there was no difference in serum MIF levels of BA patients without portal hypertension compared to that of BA patients with portal hypertension.

CONCLUSION

MIF production was elevated in BA patients compared to normal controls. It is likely that MIF plays a role in the pathophysiology of post-operative BA patients. However, the elevated MIF levels are not associated with either jaundice status or portal hypertension.

Biliary atresia: how medical complications and therapies impact outcome

Biliary atresia (BA) is a progressive fibro-obliterative disease of the extrahepatic biliary tree that presents with biliary obstruction in the neonatal period. Untreated, BA is a uniformly fatal disease and, yet, even with our existing therapies, at least 50% of children with BA will undergo liver transplantation by the age of 2 years. Current treatment strategies are, at best, palliative; they focus on prompt diagnosis, supportive nutritional care and interventions for sequelae. The purpose of this article is to discuss the current treatment paradigm for BA and to assess the impact these strategies have on outcomes. As more children with BA survive into adulthood with their native liver, it is important to understand which factors predict good and poor outcomes.

Recent advances in biliary atresia: prospects for novel therapies

BACKGROUND

Biliary atresia (BA) is a progressive fibro-obliterative disease of the extrahepatic biliary tree that presents with biliary obstruction before 2 months of age. Untreated BA is a uniformly fatal disease and even with our current therapies only 50% of children with BA will be transplant-free by 2 years of age. Despite descriptions of this disorder dating back to the 1800s our current therapies are palliative. They focus on prompt diagnosis, supportive nutritional care and interventions for sequelae.

OBJECTIVE

To present the literature supporting current treatment strategies and potential future therapies.

METHOD

Each of the aspects of care is described and the literature about nuances of care is provided.

CONCLUSION

Therapies will not improve outcomes until novel treatments are introduced, such as those suggested, which may intervene in the inflammatory or fibrotic steps of the disease process.

Evidence for the epithelial to mesenchymal transition in biliary atresia fibrosis

The epithelial to mesenchymal transition has recently been implicated as a source of fibrogenic myofibroblasts in organ fibrosis, particularly in the kidney. There is as yet minimal evidence for the epithelial to mesenchymal transition in the liver. We hypothesized that this process in biliary epithelial cells plays an important role in biliary fibrosis and might be found in patients with especially rapid forms, such as is seen in biliary atresia. We therefore obtained liver tissue from patients with biliary atresia as well as a variety of other pediatric and adult liver diseases. Tissues were immunostained with antibodies against the biliary epithelial cell marker CK19 as well as with antibodies against proteins characteristically expressed by cells undergoing the epithelial to mesenchymal transition, including fibroblast-specific protein 1, the collagen chaperone heat shock protein 47, the intermediate filament protein vimentin, and the transcription factor Snail. The degree of colocalization was quantified using a multispectral imaging system. We observed significant colocalization between CK19 and other markers of the epithelial to mesenchymal transition in biliary atresia as well as other liver diseases associated with significant bile ductular proliferation, including primary biliary cirrhosis. There was minimal colocalization seen in healthy adult and pediatric livers, or in livers not also demonstrating bile ductular proliferation. Multispectral imaging confirmed significant colocalization of the different markers in biliary atresia. In conclusion, we present significant histologic evidence suggesting that the epithelial to mesenchymal transition occurs in human liver fibrosis, particularly in diseases such as biliary atresia and primary biliary cirrhosis with prominent bile ductular proliferation.

High-dose steroids do not improve early outcome in biliary atresia

PURPOSE

Our objective was to evaluate the effects of steroids on early outcome in biliary atresia (BA).

METHODS

Patients with BA between 2001 and 2005 were reviewed. The use of steroids (4 mg/kg per day at alternate days for 1 to 3 months) has been routinely implemented since 2003. Jaundice-free status and the occurrence of cholangitis at 6 months postoperatively between patients receiving steroids and those not receiving steroids were compared.

RESULTS

Fifty-three patients with BA were studied. At 6 months postoperation, 30 patients (56.6%) were jaundice free and 24 patients (45.3%) experienced cholangitis at least once. Of the 53 patients, there were 33 patients in the steroid group and 20 patients in the nonsteroid group. The proportion of jaundice-free patients in the steroid group was higher than that in the nonsteroid group, and the proportion of patients with cholangitis in the steroid group was lower than that in the nonsteroid group. However, these discrepancies did not reach a statistically significant difference (jaundice-free status [steroid vs nonsteroid]: 20/33 [60.6%] vs 10/20 [50%], P = .57; cholangitis: 13/33 [39.4%] vs 11/20 [55%], P = .39).

CONCLUSIONS

Although the use of steroids seems to have benefits, it did not statistically improve early outcome in patients with BA.

Hyaluronic acid: additional biochemical marker in the diagnosis of biliary atresia

BACKGROUND

The purpose of the present paper was to evaluate the value of biochemical markers, including conventional liver function tests, gamma-glutamyl transferase (GGT), and hyaluronic acid (HA), in the diagnosis of neonatal cholestasis.

METHODS

Infants with neonatal jaundice were consecutively enrolled during 1 year period. The patients were diagnosed as having biliary atresia (BA) if there was either bile ductular proliferation in the portal tracts, atretic common bile duct/gallbladder, or evidence of bile duct obstruction demonstrated by liver pathology or intraoperative cholangiography, respectively. Serum HA was measured using an enzyme-linked immunosorbent assay-based test.

RESULTS

A total of 25 patients diagnosed as having BA (n = 10), neonatal hepatitis (NH; n = 9), choledochal cyst (n = 3) and parenteral nutrition-induced cholestasis (n = 3), were studied. The age at diagnosis was not significantly different between groups. Only GGT and HA were significantly elevated in the patients with BA when compared to NH (P = 0.02, P = 0.03, respectively). In BA, the median value of serum HA was 514 ng/mL (range 19-4476 ng/mL), compared to 50 ng/mL (range 19-315 ng/mL) in NH. Additionally, the serum HA level was much higher in children with choledochal cyst.

CONCLUSION

HA could be considered as a complementary biochemical marker for evaluating infants with prolonged jaundice.

Type-I but not type-II interferon receptor knockout mice are susceptible to biliary atresia

The etiology of biliary atresia (BA) is not yet understood, but recent studies have shown inflammation with an up-regulated interferon (IFN) activity in the intra- and extrahepatic bile ducts of patients with BA. These findings support an inflammatory/infectious cause of BA as mimicked in our infective murine model. To study the role of the IFN receptors in our model, we used mice with inactivated INF-alpha/beta receptor A129, with inactivated IFN-gamma receptor G129, or inactivation of both interferon receptors AG129 as well as the wild type controls W129. Mice were infected with rotavirus within 48h of birth and 7 d postpartum. The incidence of BA in each group was determined during a 3 wk period. In the second week the virus load was measured. BA incidence was 76% in A129 and 67% in AG129 animals, whereas in the G129 group only 33% of the pups developed BA. The wild type presented with a BA-incidence of 15%, while 7 d old mice failed to develop BA. There was no significant difference in the virus load of the livers between the groups independent of clinical symptoms. In conclusion, inactivation of type I INF-receptor significantly increases the incidence of BA following postpartal rotavirus infection. This effect is independent of the presence of type II-INF-receptors. Thus, in our model a type I IFN-linked deregulation of the innate immune system appears to be crucial for the induction of biliary atresia.

Extrahepatic biliary atresia demonstrates abnormal persistence of HES1 protein in neonatal biliary epithelium: an immunohistochemical study

Extrahepatic biliary atresia (EHBA) is an important cause of conjugated hyperbilirubinemia in neonates. It is a progressive disease with a poor prognosis, requiring early surgical intervention to control morbidity and mortality. The exact pathogenesis of this disorder is not known, although genetic, infectious, toxic, and/or environmental factors are thought to play a role in the causation. The Notch signaling pathway plays diverse and critical roles in development of extrahepatic and intrahepatic biliary tree. The HES family of bHLH proteins is involved in downstream signaling in the Notch pathway. We demonstrate that HES1, a principal member of this family, is normally expressed in the nuclei of human biliary epithelial cells up to 16 weeks of gestation, but not in later gestation or in the neonatal period. On the contrary, in EHBA, there is anomalous persistence of this protein for up to 3 months of postnatal life. We suggest that aberrant HES1 expression in EHBA may represent a compensatory feedback upregulation due to a putative downstream molecular defect. Further studies should be performed to evaluate the role of HES1 immunohistochemistry as a diagnostic tool in extrahepatic biliary atresia.

Role for retinoid signaling in left–right asymmetric digestive organ morphogenesis

The looping events that establish left-right asymmetries in the vertebrate gut tube are poorly understood. Retinoic acid signaling is known to impact left-right development in multiple embryonic contexts, although its role in asymmetric digestive organ morphogenesis is unknown. Here, we show that the genes for retinaldehyde dehydrogenase (RALDH2) and a retinoic acid hydroxylase (CYP26A1) are expressed in complementary patterns in the Xenopus gut during looping. A late-stage chemical genetic assessment reveals that agonists and antagonists of retinoid signaling generate abnormal gut looping topologies, digestive organ heterotaxias, and intestinal malrotations. Accessory organ deformities commonly associated with intestinal malrotation in humans, such as annular pancreas, pancreas divisum, and extrahepatic biliary tree malformations, are also induced by distinct retinoid receptor agonists. Thus, late-stage retinoic acid signaling is likely to play a critical role in asymmetric gut tube morphogenesis and may underlie the etiology of several clinically relevant defects in the digestive system.

Does "cystic" biliary atresia represent a distinct clinical and etiological subgroup? A series of three cases

We describe a unique series of 3 cases of biliary atresia (BA) associated with a choledochal cyst. All 3 children presented with jaundice at birth and had no other abnormalities. Although these children had a fetal form of BA, their presentation and outcome differed from those of biliary atresia splenic malformation syndrome (BASM), the well-described form of early onset BA. Unlike those with BASM, these children had no other associated malformations, had a normal birth weight, and did not yet require a liver transplant. We believe that the present series of patients and their associated pathology may represent a distinct phenotype with a common, prenatally acquired etiology that is different from other fetal forms of BA, such as BASM, and from patients who present with the classic perinatal form of BA.

Effective antibiotic regime for postoperative acute cholangitis in biliary atresia--an evolving scene

PURPOSE

The prompt use of empirical antibiotics is vital in managing post-Kasai cholangitis. The authors published findings of their clinical trial in 1991 and established the use of cefoperazone, with a response rate of 88.9%. Here its clinical use since its introduction is reviewed and the trend in its efficacy is assessed.

METHODS

A retrospective review was carried out between 1997 and 2003. All episodes of acute cholangitis in patients who underwent Kasai procedure were recorded. Cholangitis was defined as unexplained fever with derangement of liver enzymes. Cefoperazone was started empirically according to the established protocol, and the response to treatment was analyzed.

RESULTS

There were 19 patients with a total of 49 episodes of cholangitis. Cefoperazone was used as the first-line empirical antibiotic in 40 of these episodes. Only 30 showed successful response (75%). For the 10 unresponsive episodes, meropenem was used as second-line antibiotic with complete response in all.

CONCLUSIONS

The efficacy of cefoperazone in the treatment of post-Kasai cholangitis has decreased over the last years. This suggests a need for a more effective first-line empirical antibiotic. From this review, meropenem seems to be a suitable candidate, and a future prospective clinical trial is warranted.

Neonatal cholestasis

Any infant who is jaundiced beyond two to three weeks of life should be evaluated for neonatal cholestasis. Neonatal cholestasis is defined as accumulation of bile substances in blood due to impaired excretion. These infants should always have fractionated serum bilirubin levels checked to differentiate the conjugated hyperbilirubinemia of cholestasis from unconjugated hyperbilirubinemia that is usually benign and spontaneously resolves. Conjugated hyperbilirubinemia, pale stools and dark urine are the cardinal features of neonatal cholestasis. The differential diagnosis of cholestasis is extensive and a systematic approach is helpful to quickly establish the diagnosis. Biliary atresia is a common cause of neonatal cholestasis and affected infants need surgery before 60 days of life for better prognosis. Premature infants have multifactorial cholestasis and need a modified approach to the evaluation of cholestasis. Management of cholestasis is mostly supportive, consisting of medical management of complications of chronic cholestasis like pruritus and nutritional support for malabsorption and vitamin deficiency.

Cholestatic syndromes

PURPOSE OF REVIEW

This review highlights recent developments in the molecular pathogenesis of cholestasis as well new aspects of pathogenesis and management of clinical cholestatic disorders.

RECENT FINDINGS

Highlights include the role of nuclear receptors including FXR ligands as potential therapeutic agents, new genetic defects for pediatric cholestasis and sclerosing cholangitis, and novel infections and environmental agents as etiologies for primary biliary cirrhosis. Important clinical studies have been published in the area of pediatric cholestatic syndromes, intrahepatic cholestasis of pregnancy, primary biliary cirrhosis, primary and secondary sclerosing cholangitis, cholestasis of sepsis, viral cholestatic syndromes, and drug-induced cholestasis.

SUMMARY

These advances continue to improve understanding of the pathophysiology, diagnosis, and management of cholestatic liver disease.