Biliary atresia: From Australia to the zebrafish

Postoperative Bloodstream Infection Is Associated with Early Vascular Complications in Pediatric Liver Transplant Recipients with Biliary Atresia

Bloodstream infection (BSI) after pediatric liver transplantation (PLT) is a common and severe complication that affects patient survival. Children with biliary atresia (BA) are at an increased risk for clinically significant infections. This study evaluated the impact of post-PLT BSI on clinical outcomes in children with BA. A total of 67 patients with BA aged <18 years who underwent PLT between April 2006 and September 2020 were analyzed and divided into two groups according to the occurrence of post-PLT BSI within 1 month (BSI vs. no BSI = 13 [19.4%] vs. 54 [80.6%]). The BSI group was significantly younger at the time of PLT and had a higher frequency of BSI at the time of PLT than the no BSI group. Early vascular complications within 3 months and reoperations were significantly more frequent in the BSI group. Univariate and multivariate analyses revealed that bacteremia within 1 month of PLT and graft-to-recipient weight ratio >4% were significantly associated with vascular complications. In conclusion, BSI after PLT is associated with increased vascular complications and reoperations. Proper control of bacterial infections and early liver transplantation before uncontrolled BSI may reduce vascular complications and unexpected reoperations in children with BA.

Contribution of ADD3 and the HLA Genes to Biliary Atresia Risk in Chinese

Nonsyndromic biliary atresia (BA) is a rare polygenic disease, with autoimmunity, virus infection and inflammation thought to play roles in its pathogenesis. We conducted a genome-wide association study in 336 nonsyndromic BA infants and 8900 controls. Our results validated the association of rs17095355 in ADD3 with BA risk (odds ratio (OR) = 1.70, 95% confidence interval (95% CI) = 1.49-1.99; p = 4.07 × 10-11). An eQTL analysis revealed that the risk allele of rs17095355 was associated with increased expression of ADD3. Single-cell RNA-sequencing data and immunofluorescence analysis revealed that ADD3 was moderately expressed in cholangiocytes and weakly expressed in hepatocytes. Immuno-fluorescent staining showed abnormal deposition of ADD3 in the cytoplasm of BA hepatocytes. No ADD3 auto-antibody was observed in the plasma of BA infants. In the HLA gene region, no variants achieved genome-wide significance. HLA-DQB1 residue Ala57 is the most significant residue in the MHC region (OR = 1.44, 95% CI = 1.20-1.74; p = 1.23 × 10-4), and HLA-DQB1 was aberrantly expressed in the bile duct cells. GWAS stratified by cytomegalovirus (CMV) IgM status in 87 CMV IgM (+) BA cases versus 141 CMV IgM (-) BA cases did not yield genome-wide significant associations. These findings support the notion that common variants of ADD3 account for BA risk. The HLA genes might have a minimal role in the genetic predisposition of BA due to the weak association signal. CMV IgM (+) BA patients might not have different genetic risk factor profiles compared to CMV IgM (-) subtype.

Advances in understanding of biliary atresia pathogenesis and progression - a riddle wrapped in a mystery inside an enigma

INTRODUCTION

Biliary atresia is a potentially fatal condition of the bile ducts - both intra- and extrahepatic, for which we have no cure. Though principally a cholestatic condition, much of its pathology stems from its tendency to aggressively induce liver fibrosis and ultimately cirrhosis, only partially restrained by the portoenterostomy.

AREAS COVERED

This review is based on the current literature exploring the heterogeneous nature of biliary atresia. Thus, there are various phenotypes or variants of biliary atresia, each potentially with different etiological backgrounds caused by a number of hypothetical pathological mechanisms thought to be important in the genesis of the condition. Search methodology: the review (Oct. - Nov. 2022) is based on a search of PubMed (NLM) using main keyword 'biliary atresia' with supplementary searches using 'fibrosis'; 'inflammation'; 'BASM'; 'genetics'; 'surgery'; 'experimental'; 'etiology'; 'virology'; 'cases'; and 'syndromes.'

EXPERT OPINION

Future developments will be made on matching clinical variants with a more distinct pathophysiological discrimination and those pathways linking the initial cholestatic phase of biliary atresia to the early stages of fibrosis.

Maternal risk factors associated with offspring biliary atresia: population-based study

BACKGROUND

Biliary atresia (BA) is a progressive, idiopathic, fibro-obliterative disease of the intra and extrahepatic biliary tree. If untreated, it results in severe liver injury and death. The etiology and pathogenesis of BA remain unclear. Few studies have investigated the association between maternal illness/drug use and the occurrence of BA in offspring.

METHODS

We used the data from the Birth Certificate Application of Taiwan and linked to National Health Insurance Research Database and Taiwan Maternal and Child Health Database for the years 2004 to 2017 (N = 1,647,231) on 2022/03, and identified BA cases according to diagnosis and procedure code. A total of 285 BA cases were identified.

RESULTS

Mothers with type 2 diabetes mellitus and non-dependent drug abuse had higher rates having BA children than non-BA children, with an odds ratio of 2.17 (95% confidence interval [CI] = 1.04-4.53) and OR: 3.02 (95% CI = 1.34-6.78), respectively.

CONCLUSION

These results support the notion that BA occurrence is related to maternal reasons. Further studies should be designed to identify additional maternal and pregnancy risk factors and to understand the underlying pathophysiology.

IMPACT

1. The occurrence of offspring biliary atresia may be related to maternal illness/drug use. 2. Maternal drug abuse and type 2 diabetes mellitus pose a high risk for offspring biliary atresia. 3. If maternal etiology is found, biliary atresia might be a preventable disease.

Biliatresone: progress in biliary atresia study

BACKGROUND

Biliary atresia (BA) is one of the main causes of neonatal end-stage liver disease. Without timely diagnosis and treatment, most children with BA will develop irreversible liver fibrosis within the first two months. While current theorized causes of BA include viral infection, immune disorders, and genetic defects, the comprehensive etiology is still largely unknown. Recently, biliatresone attracted much interest for its ability to induce BA in both zebrafish and mice, so we summarized the latest progress of biliatresone research in BA and tried to answer the question of whether it could provide further clues to the etiology of human BA.

DATA SOURCES

We conducted a PubMed search for any published articles related to the topic using search terms including "biliary atresia", "biliatresone", "GSH", and "HSP90". Relevant data were extracted from the original text or supplementary materials of the corresponding articles.

RESULTS

Biliatresone had shown its unique toxicity in multiple species such as zebrafish and mice, and pathogenic factors involved included glutathione (GSH), heat shock protein 90 (HSP90) and the related pathways. In combination with epidemiological evidence and recent studies on the intestinal flora in biliary atresia, a new pathogenic hypothesis that the occurrence of biliary atresia is partly due to biliatresone or its structure-like compounds depositing in human body via vegetables or/and the altered intestinal flora structure can be tentatively established.

CONCLUSIONS

Based on the existing evidence, we emphasized that GSH and HSP90 are involved in the development of BA, and the maternal diet, especially higher vegetable intake of Asian women of childbearing age, accompanied by the altered intestinal flora structure, may contribute to the occurrence of biliary atresia and the higher incidence in the Asia group. However, the evidence from large sample epidemiological research is necessary.

[Overview of Biliary Atresia]

Biliary atresia is a progressive, idiopathic, obliterative disease of the extrahepatic biliary tree that presents with biliary obstruction in the neonatal period. It is the most common indication for liver transplantation in children. If untreated, progressive liver cirrhosis leads to death by two years of age. Nowadays, more than 90% of biliary atresia patients survive into adulthood with the development of Kasai portoenterostomy and liver transplantation technology. Early diagnosis is critical since the success rate of the Kasai portoenterostomy decreases with time. This study comprehensively reviews the recent advances in the etiology, classification, prevalence, clinical manifestations, treatment, and prognosis of biliary atresia.

Biliary Atresia Animal Models: Is the Needle in a Haystack?

Biliary atresia (BA) is a progressive fibro-obliterative process with a variable degree of inflammation involving the hepatobiliary system. Its consequences are incalculable for the patients, the affected families, relatives, and the healthcare system. Scientific communities have identified a rate of about 1 case per 10,000-20,000 live births, but the percentage may be higher, considering the late diagnoses. The etiology is heterogeneous. BA, which is considered in half of the causes leading to orthotopic liver transplantation, occurs in primates and non-primates. To consolidate any model, (1) more transport and cell membrane studies are needed to identify the exact mechanism of noxa-related hepatotoxicity; (2) an online platform may be key to share data from pilot projects and new techniques; and (3) the introduction of differentially expressed genes may be useful in investigating the liver metabolism to target the most intricate bilio-toxic effects of pharmaceutical drugs and toxins. As a challenge, such methodologies are still limited to very few centers, making the identification of highly functional animal models like finding a "needle in a haystack". This review compiles models from the haystack and hopes that a combinatorial search will eventually be the root for a successful pathway.

Biliary Atresia: A Complex Hepatobiliary Disease with Variable Gene Involvement, Diagnostic Procedures, and Prognosis

The diagnosis of biliary atresia is still terrifying at the 3rd decade of the 21st century. In a department of neonatal intensive care unit, parents and physicians face a challenge with a jaundiced baby, who may or may not have a surgically correctable hepatopathy. The approach has been systematically evaluated, but the etiology remains ambiguous. The study of families with recurrent biliary atresia has been undertaken at a molecular level. The primary interest with this disease is to identify the etiology and change the treatment from symptomatic to curative. The occurrence of this obstructive cholangio-hepatopathy in well-known genetic syndromes has suggested just coincidental finding, but the reality can be more intriguing because some of these diseases may have some interaction with the development of the intrahepatic biliary system. Several genes have been investigated thoroughly, including ADD3 and GPC1 shifting the interest from viruses to genetics. In this review, the intriguing complexities of this hepatobiliary disease are highlighted.

Update on Etiology and Pathogenesis of Biliary Atresia

Biliary atresia is a rare inflammatory sclerosing obstructive cholangiopathy that initiates in infancy as complete choledochal blockage and progresses to the involvement of intrahepatic biliary epithelium. Growing evidence shows that biliary atresia is not a single entity with a single etiology but a phenotype resulting from multifactorial events whose common path is obliterative cholangiopathy. The etiology of biliary atresia has been explained as resulting from genetic variants, toxins, viral infection, chronic inflammation or bile duct lesions mediated by autoimmunity, abnormalities in the development of the bile ducts, and defects in embryogenesis, abnormal fetal or prenatal circulation and susceptibility factors. It is increasingly evident that the genetic and epigenetic predisposition combined with the environmental factors to which the mother is exposed are potential triggers for biliary atresia. There is also an indication that a progressive thickening of the arterial middle layer occurs in this disease, suggestive of vascular remodeling and disappearance of the interlobular bile ducts. It is suggested that the hypoxia/ischemia process can affect portal structures in biliary atresia and is associated with both the extent of biliary proliferation and the thickening of the medial layer.

Epidemiological characteristics and risk factors of biliary atresia: a case-control study

OBJECTIVES

Biliary atresia (BA) is regarded as a serious neonatal hepatobiliary disease, and its aetiology and pathogenesis remain unclear. Epidemiological studies are limited, especially for the data from China. This study aims to explore risk factors of BA and provide new evidence to improve understanding of its aetiology.

DESIGN

This is a case-control study from 1 January 2015 to 31 December 2016.

SETTING

Cases were consecutively recruited from an urban tertiary care academic children's hospital in Shanghai, China, while the controls were recruited from a community hospital in Shanghai through a random sampling system.

PARTICIPANTS

721 patients suspected for BA who planned to take the diagnostic surgery were enrolled preoperatively. 613 were diagnosed with BA and recruited into the case group. Meanwhile, 688 infants without any observed major congenital anomalies or jaundice were enrolled. Finally, 594 valid questionnaires from the case group and 681 from the control group were obtained.

PRIMARY AND SECONDARY OUTCOME MEASURES

Standardised questionnaires were used for data collection. Multivariate logistic regression analysis was performed to evaluate associations reported as ORs and precision, by adjusting covariates.

RESULTS

Anxiety or stress during pregnancy was strongly associated with increased risk of BA (OR 8.36 (95% CI: 4.08 to 17.15); p<0.001), respectively. Lower birth weight, fathers from ethnic minorities of China, older age of fathers, lower income of parents, and exposure to infection, diseases and medication during pregnancy all made differences.

CONCLUSIONS

Social factors including the educational and economic background and its related anxiety and stress during pregnancy might be noticed in the occurrence of BA. Maternal infections during pregnancy in the prevalence of BA were demonstrated.

TRIAL REGISTRATION NUMBER

ChiCTR-IPR-15005885.

Biliary Atresia/Neonatal Cholestasis: What is in the Horizon?

"Biliary atresia (BA) is a common cause of jaundice in infancy. There is increasing evidence that newborn screening with direct or conjugated bilirubin leads to earlier diagnosis. Although the Kasai portoenterostomy is the primary treatment, there are scientific advances in adjuvant therapies. As pediatric patients transition to adult care, multidisciplinary care is essential, given the complexity of this patient population."

High Mobility Group Box 1 Release by Cholangiocytes Governs Biliary Atresia Pathogenesis and Correlates With Increases in Afflicted Infants

BACKGROUND AND AIMS

Biliary atresia (BA) is a devastating cholangiopathy of infancy. Upon diagnosis, surgical reconstruction by Kasai hepatoportoenterostomy (HPE) restores biliary drainage in a subset of patients, but most patients develop fibrosis and progress to end-stage liver disease requiring liver transplantation for survival. In the murine model of BA, rhesus rotavirus (RRV) infection of newborn pups results in a cholangiopathy paralleling that of human BA. High-mobility group box 1 (HMGB1) is an important member of the danger-associated molecular patterns capable of mediating inflammation during infection-associated responses. In this study, we investigated the role of HMGB1 in BA pathogenesis.

APPROACH AND RESULTS

In cholangiocytes, RRV induced the expression and release of HMGB1 through the p38 mitogen-activated protein kinase signaling pathway, and inhibition of p38 blocked HMGB1 release. Treatment of cholangiocytes with ethyl pyruvate suppressed the release of HMGB1. Administration of glycyrrhizin in vivo decreased symptoms and increased survival in the murine model of BA. HMGB1 levels were measured in serum obtained from infants with BA enrolled in the PROBE and START studies conducted by the Childhood Liver Disease Research Network. High HMGB1 levels were found in a subset of patients at the time of HPE. These patients had higher bilirubin levels 3 months post-HPE and a lower survival of their native liver at 2 years.

CONCLUSIONS

These results suggest that HMGB1 plays a role in virus induced BA pathogenesis and could be a target for therapeutic interventions in a subset of patients with BA and high HMGB1.

A Higher Incidence of Isolated Biliary Atresia in Rural Areas: Results From an Epidemiological Study in The Netherlands

OBJECTIVES

Environmental factors may be involved in the pathogenesis of biliary atresia (BA). This epidemiological study aimed to analyze the relationships between the incidence of BA, the incidence of confirmed viral or bacterial infections and population density, and geographical and temporal clustering of BA in the Netherlands.

STUDY DESIGN

Correlations between the monthly incidence of BA and the number of confirmed infections were assessed. BA incidence per province was calculated and compared to the province with highest population density. Birthplaces were classified as rural or urban. Temporal clustering of month of birth and month of conception were analyzed. We performed analyses for isolated BA (IBA) and syndromic BA (SBA) separately. Chi2, logistic regression, and Walter and Elwood test were used.

RESULTS

A total of 262 IBA and 49 SBA patients, born between 1987 and 2018, were included. IBA incidence correlated to the number of confirmed infections of, for example, Chlamydia trachomatis (R = 0.14; P = 0.02) and adenovirus (R = 0.22; P = 0.005). We observed a higher incidence of IBA (0.75/10,000; odds ratio [OR] = 1.86; P = 0.04) and SBA (0.27/10,000; OR = 6.91; P = 0.001) in Groningen and a higher incidence of SBA in Gelderland (0.13/10,000; OR = 3.35; P = 0.03). IBA incidence was 68% higher in rural (0.67/10,000) versus urban areas (0.40/10,000) (P = 0.02). The estimated month of conception of patients with SBA clustered in November (85% increase compared to average SBA incidence [0.09/10,000; P = 0.04]).

CONCLUSIONS

IBA incidence correlated weakly with national confirmed infections. IBA and SBA incidence varied geographically in the Netherlands. IBA incidence was higher in rural than in urban areas, which may be explained decreased exposure to pathogens. Our results provide support for a role of environmental factors in the pathogenesis of IBA.

Current Concepts of Biliary Atresia and Matrix Metalloproteinase-7: A Review of Literature

Biliary atresia (BA) is a rare cholangiopathy of infancy in which the bile ducts obliterate, leading to profound cholestasis and liver fibrosis. BA is hypothesized to be caused by a viral insult that leads to over-activation of the immune system. Patients with BA are surgically treated with a Kasai portoenterostomy (KPE), which aims to restore bile flow from the liver to the intestines. After KPE, progressive liver fibrosis is often observed in BA patients, even despite surgical success and clearance of their jaundice. The innate immune response is involved during the initial damage to the cholangiocytes and further differentiation of the adaptive immune response into a T-helper 1 cell (Th1) response. Multiple studies have shown that there is continuing elevation of involved cytokines that can lead to the progressive liver fibrosis. However, the mechanism by which the progressive injury occurs is not fully elucidated. Recently, matrix metalloproteinase-7 (MMP-7) has been investigated to be used as a biomarker to diagnose BA. MMPs are involved in extracellular matrix (ECM) turnover, but also have non-ECM related functions. The role of MMP-7 and other MMPs in liver fibrosis is just starting to be elucidated. Multiple studies have shown that serum MMP-7 measurements are able to accurately diagnose BA in a cohort of cholestatic patients while hepatic MMP-7 expression correlated with BA-related liver fibrosis. While the mechanism by which MMP-7 can be involved in the pathophysiology of BA is unclear, MMP-7 has been investigated in other fibrotic pathologies such as renal and idiopathic pulmonary fibrosis. MMP-7 is involved in Wnt/β-catenin signaling, reducing cell-to-cell contact by shedding of E-cadherin, amplifying inflammation and fibrosis via osteopontin (OPN) and TNF-α while it also appears to play a role in induction of angiogenesis This review aims to describe the current understandings of the pathophysiology of BA. Subsequently, we describe how MMP-7 is involved in other pathologies, such as renal and pulmonary fibrosis. Then, we propose how MMP-7 can potentially be involved in BA. By doing this, we aim to describe the putative role of MMP-7 as a prognostic biomarker in BA and to provide possible new therapeutic and research targets that can be investigated in the future.

Neonatal liver disease

Neonatal liver disease encompasses many diagnoses, including structural and genetic aetiologies. Many have significant health implications requiring long-term specialist treatment including liver transplantation. Jaundice is a common presenting feature. The ability of health-care professionals to differentiate neonatal liver disease from benign diagnoses such as physiological jaundice is very important. Persistent (more than 2 weeks) of conjugated jaundice always warrants investigation. Severe unconjugated jaundice (requiring prolonged phototherapy) should also be promptly investigated. Recent advances in genomics have enabled previously elusive, precise diagnoses in some patients with neonatal liver disease. This review paper discusses the commoner causes, with a focus on early detection and need for referral to paediatric liver services.

Biliary atresia: East versus west

Biliary atresia (BA) is a common cause of surgical jaundice during the neonatal period. It is currently considered as a spectrum of diseases with a common final pathology characterized by obliteration of the extrahepatic biliary tract and the absence of normally branching intrahepatic ducts. Though it is a global disease that can be found in all ethnicities there are some clear differences between BA arising in the East and the West. This is likely to be related to different genetic, environmental and cultural factors. BA is more frequently found in Far Eastern infants (both Chinese and Japanese) though the syndromic associations are much less common. Many Eastern countries have national screening programmes not seen in the West possibly due to debate over its cost effectiveness in countries where incidence is low. Kasai portoenterostomy (KPE) is considered as the primary treatment of BA but its outcome still remains unsatisfactory across the region. Given the complexity of BA, it is unlikely that strategic advances could be made by the sole effort of individual countries and we believe that collaboration between the East and West is the way forward.

Adjuvant treatments for biliary atresia

The treatment of biliary atresia (BA) is predominantly surgical with firstly an attempt at restoration of bile flow from the native liver by wide excision of the obstructed, obliterated extrahepatic biliary tree to the level of the porta hepatis and a portoenterostomy using a long Roux loop-Kasai portoenterostomy (KPE). Liver transplantation is reserved for those that fail this and for those where surgery is considered futile for reasons of age or stage of disease. As the aetiology of BA remains ill-defined, so adjuvant treatment has been largely based on pragmatism, trial and error. Systematic analysis of the few randomized placebo-controlled trial data and less well-controlled cohort studies have suggested benefit from post-operative high-dose steroids and ursodeoxycholic acid (UDCA) while the benefit of long-term prophylactic antibiotics, bile acid sequestrants (e.g., colestyramine) or probiotics remains unproven. Newer modalities such as antiviral therapy (AVT), immunoglobulin, FXR agonists (e.g., obeticholic acid), ileal bile acid transporter (IBAT) antagonists (e.g., maralixibat) remain unproven. This article reviews the current evidence for the efficacy of adjuvant medical therapy in BA.

Gallbladder wall abnormality in biliary atresia of mouse Sox17+/- neonates and human infants

Biliary atresia (BA) is characterized by the inflammation and obstruction of the extrahepatic bile ducts (EHBDs) in newborn infants. SOX17 is a master regulator of fetal EHBD formation. In mouse Sox17+/- BA models, SOX17 reduction causes cell-autonomous epithelial shedding together with the ectopic appearance of SOX9-positive cystic duct-like epithelia in the gallbladder walls, resulting in BA-like symptoms during the perinatal period. However, the similarities with human BA gallbladders are still unclear. In the present study, we conducted phenotypic analysis of Sox17+/- BA neonate mice, in order to compare with the gallbladder wall phenotype of human BA infants. The most characteristic phenotype of the Sox17+/- BA gallbladders is the ectopic appearance of SOX9-positive peribiliary glands (PBGs), so-called pseudopyloric glands (PPGs). Next, we examined SOX17/SOX9 expression profiles of human gallbladders in 13 BA infants. Among them, five BA cases showed a loss or drastic reduction of SOX17-positive signals throughout the whole region of gallbladder epithelia (SOX17-low group). Even in the remaining eight gallbladders (SOX17-high group), the epithelial cells near the decidual sites were frequently reduced in the SOX17-positive signal intensity. Most interestingly, the most characteristic phenotype of human BA gallbladders is the increased density of PBG/PPG-like glands in the gallbladder body, especially near the epithelial decidual site, indicating that PBG/PPG formation is a common phenotype between human BA and mouse Sox17+/- BA gallbladders. These findings provide the first evidence of the potential contribution of SOX17 reduction and PBG/PPG formation to the early pathogenesis of human BA gallbladders.This article has an associated First Person interview with the joint first authors of the paper.

Innate Immunity and Pathogenesis of Biliary Atresia

Biliary atresia (BA) is a devastating fibro-inflammatory disease characterized by the obstruction of extrahepatic and intrahepatic bile ducts in infants that can have fatal consequences, when not treated in a timely manner. It is the most common indication of pediatric liver transplantation worldwide and the development of new therapies, to alleviate the need of surgical intervention, has been hindered due to its complexity and lack of understanding of the disease pathogenesis. For that reason, significant efforts have been made toward the development of experimental models and strategies to understand the etiology and disease mechanisms and to identify novel therapeutic targets. The only characterized model of BA, using a Rhesus Rotavirus Type A infection of newborn BALB/c mice, has enabled the identification of key cellular and molecular targets involved in epithelial injury and duct obstruction. However, the establishment of an unleashed chronic inflammation followed by a progressive pathological wound healing process remains poorly understood. Like T cells, macrophages can adopt different functional programs [pro-inflammatory (M1) and resolutive (M2) macrophages] and influence the surrounding cytokine environment and the cell response to injury. In this review, we provide an overview of the immunopathogenesis of BA, discuss the implication of innate immunity in the disease pathogenesis and highlight their suitability as therapeutic targets.

Use of Zebrafish in Drug Discovery Toxicology

Unpredicted human safety events in clinical trials for new drugs are costly in terms of human health and money. The drug discovery industry attempts to minimize those events with diligent preclinical safety testing. Current standard practices are good at preventing toxic compounds from being tested in the clinic; however, false negative preclinical toxicity results are still a reality. Continual improvement must be pursued in the preclinical realm. Higher-quality therapies can be brought forward with more information about potential toxicities and associated mechanisms. The zebrafish model is a bridge between in vitro assays and mammalian in vivo studies. This model is powerful in its breadth of application and tractability for research. In the past two decades, our understanding of disease biology and drug toxicity has grown significantly owing to thousands of studies on this tiny vertebrate. This Review summarizes challenges and strengths of the model, discusses the 3Rs value that it can deliver, highlights translatable and untranslatable biology, and brings together reports from recent studies with zebrafish focusing on new drug discovery toxicology.

Serum MMP-7 in the Diagnosis of Biliary Atresia

BACKGROUND

The overlapping features of biliary atresia (BA) and other neonatal cholestasis with alternative causes (non-BA) have posed challenges for diagnosis. Matrix metalloproteinase-7 (MMP-7) has been reported to be promising in diagnosing BA. We aimed to validate the diagnostic accuracy of MMP-7 for BA in a large population sample.

METHODS

We enrolled 288 patients with neonatal obstructive jaundice from March 2017 to October 2018. Serum MMP-7 levels were measured by using an enzyme-linked immunosorbent assay. Receiver operating characteristic curves were constructed, and decision curve analysis was done. A Pearson correlation coefficient test was conducted to assess the correlation between MMP-7 levels and other characteristics.

RESULTS

The median serum MMP-7 levels were 38.89 ng/mL (interquartile range: 22.96-56.46) for the BA group and 4.4 ng/mL (interquartile range: 2.73-6.56) for the non-BA group (P < .001). The area under the receiver operating characteristic curve value was 0.9829 for MMP-7, and the sensitivity, specificity, positive predictive value, and negative predictive value were 95.19%, 93.07%, 97.27%, and 91.43%, respectively, at a cutoff value of 10.37 ng/mL. When MMP-7 was combined with γ glutamyl transferase, the diagnostic accuracy was slightly improved without significance when compared with MMP-7 alone and had an area under the curve of 0.9880 (P = .08). Decision curve analysis also showed potential for MMP-7 to be used for clinical applications. A significant correlation was found with fibrosis stage from liver biopsy (R = 0.47; P < .001).

CONCLUSIONS

MMP-7 demonstrated good accuracy in diagnosing BA and holds promise for future clinical application. Furthermore, its correlation with liver fibrosis indicated its potential use as a therapeutic target or prognostic biomarker.

Adjuvant therapy of cytomegalovirus IgM + ve associated biliary atresia: Prima facie evidence of effect

AIM OF STUDY

CMV-IgM + ve associated biliary atresia (CMV-BA) is a distinct etiological subgroup characterized by older age at presentation and a greater degree of inflammation and hepatic fibrosis, leading to a worse outcome. We report our experience with adjuvant antiviral therapy after Kasai portoenterostomy (KPE).

METHODS

Single-center prospective database identification of CMV-IgM + ve associated BA managed between 2003 and 2017. Since 2011, IV ganciclovir (5 mg/kg b.d.) and/or oral valganciclovir (520 mg/m² b.d.) were started in the early postoperative period in selected cases and continued until negativity of CMV DNA load [Anti-Viral Therapy (AVT) Group 1]. Clearance of jaundice was defined as achieving a total bilirubin ≤20 μmol/L in post-KPE period and tested with a Fisher test; native liver survival (NLS) and overall actuarial survival (OS) were compared with untreated BA CMV IgM + ve patients (Group 2) using a Log-Rank test. A P value of <0.05 was regarded as significant. Data are quoted as median (IQ range).

RESULTS

During the 14-year period, 376 infants with histologically confirmed BA were treated; of those 38(10%) were CMV IgM + ve at presentation. One child was considered too late at presentation for KPE and underwent primary liver transplantation while another only started AVT one month after KPE. Both were excluded from survival analysis. Therefore 36 underwent KPE [AVT Group 1 (n = 8) and Control Group 2 (n = 28)]. Overall age at surgery was 67(53-77) days. There was no difference in age at surgery (P = 0.26); bilirubin (P = 0.12); or AST (P = 0.15) between Group 1 and Group 2. Viral load data were available in 16 with a trend towards higher counts in the AVT group 1 [4935 (2668-18,817) vs. 1296 (253-10,471) c/ml; P = 0.06]. Clearance of jaundice was higher in AVT Group 1 (75% vs 21%, P = 0.009). There was no difference in OS (P = 0.24) but NLS was improved in the AVT Group 1 (75% vs. 25% at 2 years; P = 0.04).

CONCLUSIONS

Although this finding may be regarded as preliminary, adjuvant antiviral therapy appeared to improve outcome in infants with CMV IgM + ve BA.

LEVEL OF EVIDENCE

III.

Current management of biliary atresia based on 35 years of experience at a single center

OBJECTIVE

The prognosis of patients with biliary atresia undergoing Kasai portoenterostomy is related to the timing of the diagnosis and the indication for the procedure. The purpose of the present study is to present a practical flowchart based on 257 children who underwent Kasai portoenterostomy.

METHODS

We conducted a retrospective cohort study of patients who underwent Kasai portoenterostomy between 1981 and 2016.

RESULTS

During the first period (1981 to 2009), 230 infants were treated, and the median age at the time of surgery was 84 days; jaundice was resolved in 77 patients (33.5%). During the second period, from 2010 to 2016, a new diagnostic approach was adopted to shorten the wait time for portoenterostomy; an ultrasonography examination suggestive of the disease was followed by primary surgical exploration of the biliary tract without complementary examination or liver biopsy. Once the diagnosis of biliary atresia was confirmed, a portoenterostomy was performed during the same surgery. During this period, 27 infants underwent operations; the median age at the time of surgery was 66 days (p<0.001), and jaundice was resolved in 15 patients (55.6% - p=0.021), with a survival rate of the native liver of 66.7%.

CONCLUSION

Primary surgical exploration of the biliary tract without previous biopsy was effective at improving the prognostic indicators of patients with biliary atresia undergoing Kasai portoenterostomy.

Intrahepatic bile duct primary cilia in biliary atresia

AIM

The etiopathogenesis of non-syndromic biliary atresia (BA) is obscure. The primary aim was to investigate intrahepatic bile duct cilia (IHBC) in BA at diagnosis and its correlation with clinical outcome. The secondary aim was to analyze IHBC in routine paraffin-embedded liver biopsies using conventional scanning electron microscopy (SEM).

METHODS

Surgical liver biopsies taken at diagnosis from 22 BA infants (age range, 39-116 days) and from eight children with non-BA chronic cholestasis (age range, 162 days -16.8 years) were evaluated for IHBC by immunofluorescence (IF) and SEM. A minimum 18-month follow-up after surgery was available for all patients.

RESULTS

By IF, cilia were present in 6/8 (75%) non-BA but only in 3/22 (14%) BA cases, and cilia were reduced or absent in 19/22 (86%) BA and 2/8 (25%) non-BA livers (P < 0.01). In BA, cilia presence was found to be associated with clearance of jaundice at 6-month follow-up (P < 0.05). However, high overall survival rates with native liver, >90% at 12 months, and >70% at 24 months post-surgery, were recorded regardless of cilia presence/absence at diagnosis. Electron microscopy was able to detect bile ducts and cilia in routine liver biopsies, revealing significant abnormalities in 100% BA livers.

CONCLUSIONS

The presence of IHBC in BA livers at the diagnosis was associated with resolution of cholestasis, although was not predictive of short-term survival with native liver. Scanning electron microscopy represents a powerful new tool to study routine liver biopsies in biliary disorders. Cilia dysfunction in BA pathogenesis and/or disease progression warrants further investigation.

Ethnic Disparity in the Incidence and Outcome of Biliary Atresia in New Zealand

To determine incidence and outcome of biliary atresia (BA) between ethnic groups in New Zealand (NZ), a retrospective review was undertaken of children with BA born between 2002 and 2014. Prioritized ethnicity was used to determine ethnicity and was compared to population data. Uni- and multivariate analyses were undertaken to determine demographic and biochemical factors associated with outcome. Overall incidence was 1 in 9181 (Māori 1 in 5285; European 1 in 16,228; P < 0.0001). Overall and transplant-free survival rates at 1, 2, and 5 years were 92%, 86%, 82% and 70%, 49%, 30% respectively with Māori having improved transplant-free survival (P < 0.05) despite European children undergoing Kasai earlier (49 vs 63 days). BA is more common in NZ than Europe and North America, which is attributable to a higher incidence in Māori but overall outcome is poorer. Māori have improved transplant-free survival compared to NZ European children but the reason is unknown.

Prenatal diagnosis of biliary atresia: A case series

BACKGROUND

Biliary atresia is a progressive disease presenting with jaundice, and is the most common indication for liver transplantation in the pediatric population. Prenatal series have yielded conflicting results concerning a possible association between BA and prenatal nonvisualization of the gallbladder.

AIMS

This retrospective case series was performed to assess the association between biliary atresia, prenatal nonvisualization of the gallbladder and other sonographic signs.

STUDY DESIGN/SUBJECTS

We identified biliary atresia patients who underwent a Kasai procedure by a single pediatric surgeon and/or follow up by a single pediatric gastroenterologist. Axial plane images and/or video recordings were scrutinized for sonographic signs of biliary atresia on the second trimester anomaly scan.

OUTCOME MEASURES

Proportion of biliary atresia cases with prenatal sonographic signs.

RESULTS

Twenty five charts of children with biliary and high quality prenatal images were retrieved. 6/25 (24%) of cases analyzed had prenatal nonvisualization of the gallbladder or a small gallbladder on the prenatal scan. Two cases had biliary atresia splenic malformation syndrome. None of the cases had additional sonographic markers of biliary atresia.

CONCLUSIONS

Our study suggests that in addition to the well-established embryonic and cystic forms, an additional type can be suspected prenatally, which is characterized by prenatal nonvisualization of the gallbladder in the second trimester. This provides additional evidence that some cases of BA are of fetal rather than perinatal onset and may have important implications for prenatal diagnosis, for counseling and for research of the disease's etiology and pathophysiology.

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.

Somatic mutation, a cause of biliary atresia: A hypothesis

Despite many years of research, the causes of biliary atresia still remain elusive. Infection, immune disorder, toxins or maternal microchimerism have been cited as potential triggers of biliary atresia. This is a rare disease with a stable incidence over the years although with sizeable ethnic variations. This stability suggests that environmental factors have in fact only a slight influence. During the search for etiologies, twin studies have often helped disentangle the genetic from the environmental. For this condition, twin studies have mainly demonstrated a lack of concordance between twins (either monozygotic or dizygotic), ruling out Mendelian, infectious or toxic causes. Indeed, for toxic or infectious embryopathy, the concordance for twins (especially monozygotic) is about 80%. Paradoxically, these data suggest that biliary atresia has neither a genetic nor an environmental cause. One way of severing the Gordian knot is to hypothesize a role for post zygotic somatic mutation, leading to genetic mosaicism (as a cause of biliary atresia). In recent years, post zygotic mutation has been identified as a cause of non-cancerous disease ranging from dysmorphic syndrome to specific organ abnormalities. A potential model for this condition could be post zygotic mutation or copy number variations in genes or regulatory regions, triggering the cascade of events leading to inflammatory and obliterative cholangiopathy. These events could be enhanced by genetic susceptibility explaining the ethnic variations. In these models, the rate of mosaicism in different parts of the liver could explain the success rate of the Kasai procedure. This hypothesis can be tested: as most children with biliary atresia are eligible for the Kasai procedure, genetic material from the liver and ductal plate can be collected easily. If the hypothesis is correct, whole genome sequencing or copy number variation studies at individual cell level should allow to identify the expected low level of genetic mosaicism. Thus, we hypothesize that postzygotic somatic mutation may play a part in the physiopathology of biliary atresia.

On the development of the hepatopancreatic ductal system

The hepatopancreatic ductal system is the collection of ducts that connect the liver and pancreas to the digestive tract. The formation of this system is necessary for the transport of exocrine secretions, for the correct assembly of the pancreatobiliary ductal system, and for the overall function of the digestive system. Studies on endoderm organ formation have significantly advanced our understanding of the molecular mechanisms that govern organ induction, organ specification and morphogenesis of the major foregut-derived organs. However, little is known about the mechanisms that control the development of the hepatopancreatic ductal system. Here, we provide a description of the different components of the system, summarize its development from the endoderm to a complex system of tubes, list the pathologies produced by anomalies in its development, as well as the molecules and signaling pathways that are known to be involved in its formation. Finally, we discuss its proposed potential as a multipotent cell reservoir and the unresolved questions in the field.