Evidence for Viral Induction of Biliary Atresia: A Review

Incidence of biliary atresia in the United States before and during the COVID-19 pandemic

OBJECTIVES

The etiology of biliary atresia (BA) is unclear and potentially involves viral triggers. We aimed to compare the incidence of BA in the United States before and during the coronavirus disease 2019 (COVID-19) pandemic, focusing on potential associations with viral circulation disruptions caused by nonpharmaceutical interventions (NPIs).

METHODS

We queried the Pediatric Health Information System® (PHIS) for all patients discharged with BA between January 1, 2010, and January 31, 2024. Using CDC WONDER, we calculated monthly and overall incidence rates of BA per 1,000,000 live births. We fit a Poisson regression model to assess the association between the widespread implementation of stay-at-home orders (using April 1, 2020, as the cutoff date) and the incidence of BA, accounting for national natality fluctuations.

RESULTS

We identified 3456 newborns with BA from 42 hospitals; 2997 (86.7%) were born before and 459 (13.3%) were born during the pandemic. The mean monthly number of newborns with BA was 24.0 (95% confidence interval, 23.0-25.0) for an overall incidence rate of 74.4 (71.5-77.4) per 1,000,000 live births. We did not identify a statistically significant year-to-year contrast in the incidence of BA before (incidence rate ratio [IRR] = 0.995 [0.983-1.008]; p = 0.49) or after the cutoff date (IRR = 0.999 [0.895-1.116]; p = 0.99). In addition, we did not identify sufficient evidence that trends differed between the two periods (IRR = 1.00 [0.893-1.128]; p = 0.95).

CONCLUSIONS

The NPIs implemented during the COVID-19 pandemic were not significantly associated with changes in the incidence or temporal pattern of BA.

Biliary atresia susceptibility gene EFEMP1 regulates extrahepatic bile duct elastic fiber formation and mechanics

Background & Aims

EGF-containing fibulin extracellular matrix protein 1 (EFEMP1, also called fibulin-3) is an extracellular matrix protein linked in a genome-wide association study to biliary atresia, a fibrotic disease of the neonatal extrahepatic bile duct. Fibulin-3 is deposited in most tissues and Efemp1 null mice have decreased elastic fibers in visceral fascia; however, fibulin-3 does not have a role in the development of large elastic fibers and its overall function in the extrahepatic bile ducts remains unclear.

Methods

We used staining and histology to define the amount and organization of key extracellular matrix components in the extrahepatic bile ducts. We also repurposed pressure myography, a technique heretofore applied to the vasculature, to determine the contribution of elastin and fibulin-3 to extrahepatic bile duct mechanics. We examined extrahepatic bile duct structure and mechanics in three models: neonatal vs. adult rat ducts (n = 6 each), elastase-treated adult rat ducts (n = 6-7 each), and Efemp1 +/- vs. wild-type mouse ducts (n = 6 each).

Results

We demonstrated that fibulin-3 is expressed in the submucosa of both neonatal and adult mouse, rat and human extrahepatic bile ducts and that, in adult Efemp1 +/- mouse ducts, elastin organization into fibers is decreased by approximately half. Pressure myography showed that Efemp1 +/- ducts have altered mechanics compared to control ducts, with Efemp1 +/- ducts displaying significant stretch compared to controls (p = 0.0376); these changes in stretch are similar to those observed in elastase-treated vs. normal ducts (p <0.0001) and in neonatal ducts vs. adult ducts (p <0.0001).

Conclusion

Fibulin-3 has an important role in the formation of elastic fibers and the mechanical properties of the extrahepatic bile duct. This provides functional relevance for the biliary atresia susceptibility gene EFEMP1.

Impact and implications

The gene EFEMP1 was found via a genome-wide association study to be a susceptibility gene for the neonatal disease biliary atresia. EFEMP1 encodes the protein fibulin-3, which regulates elastic fiber organization in the extrahepatic bile duct (EHBD), the major site of disease in biliary atresia. We showed that neonatal EHBDs as well as mice heterozygous for Efemp1 have decreased numbers of elastic fibers, and that this alters EHBD mechanics. This work is important for understanding the mechanism of biliary atresia, in particular susceptibility to obstruction.

Immunology of Biliary Atresia

Biliary atresia is a progressive neonatal cholangiopathy that leads to liver failure. Characterized by inflammation-mediated liver injury, the immune system plays a critical role in the pathogenesis of this disease. Though several types of immune cells and mediators have been implicated in animal models of biliary atresia, emerging literature reflects the complex interplay of components of the immune response that contributes to disease progression in humans. Novel therapies targeting the immune system are needed to mitigate the devastating effects of biliary atresia. This review highlights the current literature on the components of the immune system that have been in implicated in biliary atresia and the rich interplay between the major arms of the immune system- innate and adaptive immunity- to cause the highly morbid consequences of this disease.

A G3P[3] bat rotavirus can infect cultured human cholangiocytes and cause biliary atresia symptom in suckling mice

•Bat rotavirus strain MSLH14 (G3P[3]) can infect human cholangiocytes in vitro . •MSLH14 can cause suckling mice biliary atresia symptom, indicating potential public health risks. •MSLH14 have the potential for establishing a biliary atresia animal model.

Expression of activin A in liver tissue and the outcome of patients with biliary atresia

Biliary atresia (BA) is a rare disease of unknown etiology which leads to cirrhosis and death if left untreated. The standard of care is an early hepatoportoenterostomy (HPE). Long-term follow-up is mandatory, during which most patients will require a liver transplant. Activin A belongs to the transforming growth factor-β (TGF-β) superfamily. TGF-β is a central regulator in chronic liver disease. We have studied the expression of activin A in liver tissue collected intraoperatively during the HPE. We included patients who underwent HPE in a single medical center. Clinical, ultrasonographic, and pathohistological data were collected. Activin A immunostaining was performed. Expression in the bile duct epithelium and hepatocytes was scored as either weakly positive, moderately positive, or strongly positive. Patients were then divided into three groups accordingly. We observed the outcome after the HPE at 3 months, 2 years, and at the end of follow-up. The study encompassed 37 patients. At 3 months after HPE, 92.3% of those with a weakly positive activin A reaction (group A) achieved good jaundice clearance, whereas only 44.4% of those with a moderately (group B) and 40% of those with a strongly positive reaction (group C) achieved good jaundice clearance (p = 0.008). Furthermore, 2 years after the HPE, 92.3% of those in group A survived with native liver (SNL), but only 33.3% of those in group B and 46.7% of those in group C had SNL (p = 0.007). At the end of follow-up, 83.3% of those in group A survived with native liver, as did 33.3% in group B and 40% in group C. Activin A is a valuable pathohistological predictor of the outcome of BA after an HPE.

A triad of gut dysbiosis, dysregulated immunity, and 'leaky' gut characterize HCMV associated neonatal cholestasis

BACKGROUND

Gut microbiome dysbiosis and related immune dysfunction have been associated with the pathogenesis of Human Cytomegalovirus (HCMV) infection in infants with neonatal cholestasis (NC) as previously reported by us. However, the interaction of a perturbed microbiome, HCMV infection, and dysregulated immunity leading to exacerbation of disease severity has not been investigated so far. In this study, we examined the association of gut microbiome, host inflammatory and homeostatic markers that are likely to govern increased pathogenesis of NC in HCMV infected IgM positive infants (N = 15) compared to IgM negative (N = 15) individuals. Stool samples of HCMV infected infants and age-matched healthy controls (N = 10) were assessed for gut bacteria-derived metabolites like short-chain fatty acids (SCFAs), Lipopolysaccharide (LPS), cytokines and markers of gut barrier integrity. Data were correlated with previously determined gut microbiome composition and frequency of immune cell subsets. Finally, validation of clinical potential was undertaken by principal component analysis (PCA) of integrated data to delineate the spectrum of clinical pathology.

RESULTS

Significantly lower levels of SCFAs and elevated fecal levels of soluble inflammatory mediators were observed in IgM positive HCMV infected infants. Further, increased plasma LPS levels and markers of gut permeability, suggestive of microbial translocation due to a 'leaky gut' were observed in HCMV infected IgM positive group. PCA of integrated data revealed clearly disparate profiles representative of IgM positive, IgM negative, and uninfected healthy states.

CONCLUSION

Our results suggest the utility of an integrated approach involving dysregulated microbiome-immune axis for gaining a better understanding of pathogenesis associated with HCMV infection in NC.

Heritable Chronic Cholestatic Liver Diseases: A Review

Chronic cholestasis due to heritable causes is usually diagnosed in childhood. However, many cases can present and survive into adulthood. The time course varies considerably depending on the underlying etiology. Laboratory data usually reveal elevated conjugated hyperbilirubinemia, alkaline phosphatase, and gamma-glutamyl transpeptidase. Patients may be asymptomatic; however, when present, the typical symptoms are pruritus, jaundice, fatigue, and alcoholic stools. The diagnostic methods and management required depend on the underlying etiology. The development of genome-wide associated studies has allowed the identification of specific genetic mutations related to the pathophysiology of cholestatic liver diseases. The aim of this review was to highlight the genetics, clinical pathophysiology, presentation, diagnosis, and treatment of heritable etiologies of chronic cholestatic liver disease.

Biliary atresia: the role of gut microbiome, and microbial metabolites

Biliary atresia (BA) is a progressive fibroinflammatory disease affecting both the extrahepatic and intrahepatic bile ducts, potentially leading to chronic cholestasis and biliary cirrhosis. Despite its prevalence, the exact mechanisms behind BA development remain incompletely understood. Recent research suggests that the gut microbiota and its metabolites may play significant roles in BA development. This paper offers a comprehensive review of the changing characteristics of gut microbiota and their metabolites at different stages of BA in children. It discusses their influence on the host's inflammatory response, immune system, and bile acid metabolism. The review also explores the potential of gut microbiota and metabolites as a therapeutic target for BA, with interventions like butyrate and gut microbiota preparations showing promise in alleviating BA symptoms. While progress has been made, further research is necessary to untangle the complex interactions between gut microbiota and BA, paving the way for more effective prevention and treatment strategies for this challenging condition.

Biliary atresia

Biliary atresia (BA) is a progressive inflammatory fibrosclerosing disease of the biliary system and a major cause of neonatal cholestasis. It affects 1:5,000-20,000 live births, with the highest incidence in Asia. The pathogenesis is still unknown, but emerging research suggests a role for ciliary dysfunction, redox stress and hypoxia. The study of the underlying mechanisms can be conceptualized along the likely prenatal timing of an initial insult and the distinction between the injury and prenatal and postnatal responses to injury. Although still speculative, these emerging concepts, new diagnostic tools and early diagnosis might enable neoadjuvant therapy (possibly aimed at oxidative stress) before a Kasai portoenterostomy (KPE). This is particularly important, as timely KPE restores bile flow in only 50-75% of patients of whom many subsequently develop cholangitis, portal hypertension and progressive fibrosis; 60-75% of patients require liver transplantation by the age of 18 years. Early diagnosis, multidisciplinary management, centralization of surgery and optimized interventions for complications after KPE lead to better survival. Postoperative corticosteroid use has shown benefits, whereas the role of other adjuvant therapies remains to be evaluated. Continued research to better understand disease mechanisms is necessary to develop innovative treatments, including adjuvant therapies targeting the immune response, regenerative medicine approaches and new clinical tests to improve patient outcomes.

Maternal Prenatal Infections and Biliary Atresia in Offspring

Importance

Investigations into the association of antepartum maternal infections with the pathogenesis of biliary atresia (BA) in human offspring are insufficient.

Objective

To examine the association between prenatal infections in mothers and the development of BA in their offspring.

Design, Setting, and Participants

This population-based case-control study obtained administrative data from the Taiwan National Health Insurance Research Database with linkage to the Taiwan Maternal and Child Health Database, capturing demographic and medical information on nearly all 23 million of the Taiwan population. The cohort comprised 2 905 978 singleton live births among mother-infant dyads between January 1, 2004, and December 31, 2020, in Taiwan. The case group of infants with BA was identified from use of International Classification of Diseases diagnostic codes for BA and subsequent Kasai procedure or liver transplant. The control group was randomly selected from infants without BA, representing approximately 1 in 1000 study population. Data analyses were performed from May 1 to October 31, 2023.

Exposure

Prenatal maternal infections, including intestinal infection, influenza, upper airway infection, pneumonia, soft-tissue infection, and genitourinary tract infection.

Main Outcomes and Measures

The main outcome was exposure to prenatal maternal infections. Inverse probability weighting analysis was performed by building a logistic regression model to estimate the probability of the exposure observed for a particular infant and using the estimated probability as a weight in subsequent analyses. The weighted odds ratio (OR) estimated by logistic regressions was then used to assess the risk of BA in offspring after prenatal maternal infections.

Results

Among the mother-infant dyads included, 447 infants with BA were cases (232 females [51.9%]) and 2912 infants without BA were controls (1514 males [52.0%]). The mean (SD) maternal age at childbirth was 30.7 (4.9) years. Offspring exposed to prenatal intestinal infection (weighted OR, 1.46; 95% CI, 1.17-1.82) and genitourinary tract infection (weighted OR, 1.22; 95% CI, 1.05-1.41) in mothers exhibited a significantly higher risk of BA. Furthermore, maternal intestinal infection (weighted OR, 6.05; 95% CI, 3.80-9.63) and genitourinary tract infection (weighted OR, 1.55; 95% CI, 1.13-2.11) that occurred during the third trimester were associated with an increased risk of BA in offspring.

Conclusions and Relevance

Results of this case-control study indicate an association between prenatal intestinal infection and genitourinary tract infection in mothers and BA occurrence in their offspring. Further studies are warranted to explore the underlying mechanisms of this association.

Insight into the mechanism of gallstone disease by proteomic and metaproteomic characterization of human bile

Introduction

Cholesterol gallstone disease is a prevalent condition that has a significant economic impact. However, the role of the bile microbiome in its development and the host's responses to it remain poorly understood.

Methods

In this study, we conducted a comprehensive analysis of microbial and human bile proteins in 40 individuals with either gallstone disease or gallbladder polyps. We employed a combined proteomic and metaproteomic approach, as well as meta-taxonomic analysis, functional pathway enrichment, and Western blot analyses.

Results

Our metaproteomic analysis, utilizing the lowest common ancestor algorithm, identified 158 microbial taxa in the bile samples. We discovered microbial taxa that may contribute to gallstone formation, including β-glucuronidase-producing bacteria such as Streptococcus, Staphylococcus, and Clostridium, as well as those involved in biofilm formation like Helicobacter, Cyanobacteria, Pseudomonas, Escherichia coli, and Clostridium. Furthermore, we identified 2,749 human proteins and 87 microbial proteins with a protein false discovery rate (FDR) of 1% and at least 2 distinct peptides. Among these proteins, we found microbial proteins crucial to biofilm formation, such as QDR3, ompA, ndk, pstS, nanA, pfIB, and dnaK. Notably, QDR3 showed a gradual upregulation from chronic to acute cholesterol gallstone disease when compared to polyp samples. Additionally, we discovered other microbial proteins that enhance bacterial virulence and gallstone formation by counteracting host oxidative stress, including sodB, katG, rbr, htrA, and ahpC. We also identified microbial proteins like lepA, rtxA, pckA, tuf, and tpiA that are linked to bacterial virulence and potential gallstone formation, with lepA being upregulated in gallstone bile compared to polyp bile. Furthermore, our analysis of the host proteome in gallstone bile revealed enhanced inflammatory molecular profiles, including innate immune molecules against microbial infections. Gallstone bile exhibited overrepresented pathways related to blood coagulation, folate metabolism, and the IL-17 pathway. However, we observed suppressed metabolic activities, particularly catabolic metabolism and transport activities, in gallstone bile compared to polyp bile. Notably, acute cholelithiasis bile demonstrated significantly impaired metabolic activities compared to chronic cholelithiasis bile.

Conclusion

Our study provides a comprehensive metaproteomic analysis of bile samples related to gallstone disease, offering new insights into the microbiome-host interaction and gallstone formation mechanism.

Immune-mediated cholangiopathies in children: the need to better understand the pathophysiology for finding the future possible treatment targets

Cholangiopathies are defined as focal or extensive damage of the bile ducts. According to the pathogenetic mechanism, it may be immune-mediated or due to genetic, infectious, toxic, vascular, and obstructive causes. Their chronic evolution is characterized by inflammation, obstruction of bile flow, cholangiocyte proliferation, and progression toward fibrosis and cirrhosis. Immune-mediated cholangiopathies comprise primary sclerosing cholangitis (PSC), autoimmune cholangitis and IgG4-associated cholangitis in adults and biliary atresia (BA), neonatal sclerosing cholangitis (NSC) in children. The main purpose of this narrative review was to highlight the similarities and differences among immune-mediated cholangiopathies, especially those frequent in children in which cholangiocyte senescence plays a key role (BA, NSC, and PSC). These three entities have many similarities in terms of clinical and histopathological manifestations, and the distinction between them can be hard to achieve. In BA, bile duct destruction occurs due to aggression of the biliary cells due to viral infections or toxins during the intrauterine period or immediately after birth. The consequence is the activation of the immune system leading to severe inflammation and fibrosis of the extrahepatic biliary tract, lumen stenosis, and impairment of the biliary flow. PSC is characterized by inflammation and fibrosis of intra- and extrahepatic bile ducts, leading to secondary biliary cirrhosis. It is a multifactorial disease that occurs because of genetic predisposition [human leukocyte antigen (HLA) and non-HLA haplotypes], autoimmunity (cellular immune response, autoantibodies, association with inflammatory bowel disease), environmental factors (infections or toxic bile), and host factors (intestinal microbiota). NSC seems to be a distinct subgroup of childhood PSC that appears due to the interaction between genetic predisposition (HLA B8 and DR3) and the disruption of the immune system, validated by elevated IgG levels or specific antibodies [antinuclear antibody (ANA), anti-smooth muscle antibody (ASMA)]. Currently, the exact mechanism of immune cholangiopathy is not fully understood, and further data are required to identify individuals at high risk of developing these conditions. A better understanding of the immune mechanisms and pathophysiology of BA, NSC, and PSC will open new perspectives for future treatments and better methods of preventing severe evolution.

A novel gut microbiome-immune axis influencing pathology in HCMV infected infants with neonatal cholestasis

The interplay of active HCMV infection with gut dysbiosis in the immunopathology of cholestasis in neonates and infants remains unexplored. In this study, we evaluated gut microbiome profiles and immune dysfunction in a cohort of HCMV infected cholestatic infants (IgM positive, N = 21; IgM negative, N = 25) compared to healthy infants, N = 10. HCMV infected IgM positive individuals exhibited increased clinical severity in terms of liver dysfunction, altered CD4+: CD8+ ratio, and elevated Granzyme B levels in cellular immune subsets. Gut microbiome analysis revealed distinct and differential diversity and composition within infected groups aligned with clinical severity reflected through the increased abundance of Gammaproteobacteria, reduced Bifidobacteria, and a unique signature mapping to the HCMV infected IgM negative group. Correlation analyses revealed associations between Bifidobacterium breve, Gammaproteobacteria, Firmicutes, Clostridia, Finegoldia magna, Veillonella dispar, and Granzyme B expressing immune cell subsets. Our study describes a novel gut microbiome-immune axis that may influence disease severity in cholestatic infants with active HCMV infection.

Reduced Presentation of Biliary Atresia During the COVID-19 Lockdown: A Population Based Observational Study

OBJECTIVE

The aim of this study was to assess whether there has been a change in presentations of biliary atresia (BA) in England and Wales during the first and second coronavirus disease 2019 (COVID-19) lockdowns (January-June 2020 and 2021).

DESIGN

This population study assessed all confirmed cases of BA, from January 2020 to December 2021 across the 3 UK pediatric liver centers originating from England and Wales. Data was then compared to the incidence of confirmed BA cases from January to December 2017, 2018, and 2019.

RESULTS

During January-June 2020 and 2021, there were only 8 and 12 presenting cases of BA in England and Wales, compared to 16, 13, and 18 for the same time periods in 2017, 2018, and 2019, respectively. This difference was significant in a two-sided t test for 2020 ( P = 0.035) but not for 2021 ( P = 0.385). There was no difference in the mean days to Kasai procedure in January-June 2020 and 2021 compared to 2017-2019; however average time to Kasai after the lockdown periods was significantly higher.

CONCLUSIONS

There was a significant reduction in the presenting cases of BA during the first COVID-19 lockdown, with an increased time for BA referrals after the pandemic lockdowns were lifted in England and Wales.

Effect of Cytomegalovirus Infection on Initial Presentation and Overall Prognosis of Biliary Atresia Patients

Background and Aim

Biliary atresia is known to have a multifactorial etiology and perinatal infection with hepatotropic viruses such as cytomegalovirus (CMV) is a probable trigger in a subset of patients. The aim of the current study is to evaluate the effects of CMV association of biliary atresia on the initial presentation of patients and their response to Kasai portoenterostomy.

Patients and Methods

We conducted a retrospective, single-center study on 20 patients of biliary atresia and classified them into two groups based on their CMV immunoglobulin M (IgM) positivity. We compared the age of initial presentation, the liver biochemistry at presentation, immediate and delayed follow-up, rate of jaundice clearance following Kasai portoenterostomy, and histopathology of liver between the two groups. Data were reported in terms of means, and P < 0.05 was considered significant.

Results

Out of 20 cases of biliary atresia, 60% (n = 12) were CMV IgM positive. Infants with CMV-positive status were noted to be older at presentation (88.5 days [65-150 days] vs. 83 days [45-160 days] P < 0.05) were more jaundiced at presentation (total bilirubin - 13.51 mg/dl [9.09-15.99 mg/dl] vs. 11.83 mg/dl [6.5-13.5 mg/dl] P < 0.05), had higher alkaline phosphatase (751.2 IU/L [387-1951 IU/L] vs. 621.75 IU/L [172-857 IU/L] P < 0.05), higher gamma-glutamyl transferase levels (505.58 IU/L [376-1127 IU/L] vs. 376.75 IU/L [186-624 IU/L] P < 0.05), and had higher incidence of splenomegaly. The rate of resolution of jaundice postKasai portoenterostomy was also evidently less in CMV-positive patients. Four out of 12 patients have bilirubin >2 mg/dl at a 6-month follow-up.

Conclusion

CMV-associated biliary atresia patients have delayed initial presentation and impaired jaundice clearance postKasai portoenterostomy. The role of antiviral therapy should be studied in this subset of patients.

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.

Maternal regulation of biliary disease in neonates via gut microbial metabolites

Maternal seeding of the microbiome in neonates promotes a long-lasting biological footprint, but how it impacts disease susceptibility in early life remains unknown. We hypothesized that feeding butyrate to pregnant mice influences the newborn’s susceptibility to biliary atresia, a severe cholangiopathy of neonates. Here, we show that butyrate administration to mothers renders newborn mice resistant to inflammation and injury of bile ducts and improves survival. The prevention of hepatic immune cell activation and survival trait is linked to fecal signatures of Bacteroidetes and Clostridia and increases glutamate/glutamine and hypoxanthine in stool metabolites of newborn mice. In human neonates with biliary atresia, the fecal microbiome signature of these bacteria is under-represented, with suppression of glutamate/glutamine and increased hypoxanthine pathways. The direct administration of butyrate or glutamine to newborn mice attenuates the disease phenotype, but only glutamine renders bile duct epithelial cells resistant to cytotoxicity by natural killer cells. Thus, maternal intake of butyrate influences the fecal microbial population and metabolites in newborn mice and the phenotypic expression of experimental biliary atresia, with glutamine promoting survival of bile duct epithelial cells.

The pathogenesis of biliary atresia remains poorly understood. Here, the authors report that maternal butyrate treatment alters the gut microbiome and glutamine/hypoxanthine metabolites similar to human subjects, and suppresses biliary atresia in newborn mice.

Genetic Factors and Their Role in the Pathogenesis of Biliary Atresia

Biliary Atresia, a common basis for neonatal cholestasis and primary indication for Liver Transplantation, accounts for 60% of pediatric Liver Transplantations. While the pathogenesis of Biliary Atresia remains obscure, abnormalities within bile ducts and the liver, inflammation, fibrosis and cilia defects are thought to comprise the pathological basis for this condition. The findings of genetic variants in Biliary Atresia, such as Copy Number Variations and Single Nucleotide Polymorphism, are considered as essential factors in the development of this condition. In this review, we summarize and analyze these Biliary Atresia variants from a perspective of their pathological characteristics. In conclusion, such analyses may offer novel insights into the pathogenesis of Biliary Atresia and provide a foundation for future studies directed toward a better understanding and treatment of Biliary Atresia.

Biliary Atresia - emerging diagnostic and therapy opportunities

Biliary Atresia is a devastating pediatric cholangiopathy affecting the bile ducts of the liver. In this review, we describe recent progress in the understanding of liver development with a focus on cholangiocyte differentiation and how use of technical platforms, including rodent, zebrafish and organoid models, advances our understanding of Biliary Atresia. This is followed by a description of potential pathomechanisms, such as autoimmune responses, inflammation, disturbed apical-basal cell polarity, primary cilia dysfunction as well as beta-amyloid accumulation. Finally, we describe current and emerging diagnostic opportunities and recent translation breakthroughs for Biliary Atresia in the area of emerging therapy development, including immunomodulation and organoid-based systems for liver and bile duct repair.

The impact of rotavirus vaccination in the prevalence of gastroenteritis and comorbidities among children after suboptimal rotavirus vaccines implementation in Taiwan: A population-based study

In Taiwan, rotavirus vaccination was implemented in 2006 in the private sector. The population-based impact of rotavirus vaccination on gastroenteritis and comorbidities of children remains under-investigated.We analyzed the annual prevalence of rotavirus-related disease, including gastroenteritis, convulsions, epilepsy, type I diabetes mellitus, intussusception, and biliary atresia among children under 5 years of age. Data were collected from Taiwan's National Health Insurance Research Database, a nationwide population-based database. A 16-year retrospective cohort study was conducted between 2000 and 2015.Among children <5 years of age, the prevalence of gastroenteritis decreased after 2012 (44,259.69 per 100 thousands) and remained lower through 2015 (39,931.11per 100 thousands, P < .001). The prevalence of convulsions rose steadily and significantly from 2007 (775.90 per 100 thousands) to 2015 (962.17 per 100 thousands, P < .001). The prevalence of epilepsy decreased significantly until reaching a nadir in 2013 (from 501.56 to 293.53 per 100 thousands, P < .001). The prevalence of biliary atresia tended upward, and surged suddenly in 2007 with a peak in 2013 (18.74 per 100 thousands). Among infants (<1 year of age) from 2000 to 2015, the prevalence of gastroenteritis declined steadily, and more rapidly after 2007 (22,513 to 17,285 per 100 thousands).In Taiwan, after introducing rotavirus vaccination, gastroenteritis in young children decreased, especially in infancy. However, gastroenteritis is still common in children, given other emerging pathogens. Our results highlight the impact of rotavirus vaccines on children's health in Taiwan and provide indications for future preventive medicine and healthcare strategies in children.

The usefulness of immunohistochemical staining of bile tracts in biliary atresia

Aim of the study

To assess ductular proliferation (DP) and ductal plate malformation (DPM) in biliary atresia (BA) by means of immunohistochemical staining using cytokeratins CK7 and CK19 and neural cell adhesion molecule (NCAM) antibody CD56.

Material and methods

In 10 cases of BA, liver surgical biopsies obtained at the time of hepatoportoenterostomy were stained with H&E, PAS, Gomori and Azan methods. Immunohistochemical technique was used to outline bile ducts, ductular reaction, reactive bile duct/ductules and DPM by CK7, CK19 and NCAM antibody CD56.

Results

We found fibrosis, bile stasis and mild inflammation in all cases. In the routine staining DP was not seen in 3 cases. The immunohistochemical staining by means of CK19 was helpful in the detection of DP, and allowed it to be demonstrated in all cases. The biliary epithelial cell markers for CD56, CK7, CK19 were used for demonstration of bile duct cell but not hepatocyte alterations in the structure of intrahepatic biliary ducts and different stages of maturation. CD56 as a marker of immature bile ducts was expressed on biliary epithelium of bile ducts and bizarre forms of DPM in 6 cases. The positive expression of CD56 corresponded to the co-localization of CK19 of DPM, but not CK7, to the ductular reaction at the limiting plate of portal tracts. CD7, considered as a marker of DP, also stained ductal hepatocytes and multipotential oval cells, and was a marker of DPM in 3 cases.

Conclusions

Use of CK7, CK19 and CD56 is helpful in BA diagnosis and allows differentiation of the stage of developing bile duct cells according to the expression pattern.

Recent developments in etiology and disease modeling of biliary atresia: a narrative review

Biliary atresia (BA) is a rare but severe fibroinflammatory disease of the extrahepatic and the intrahepatic bile ducts. Without prompt interventions, BA has fatal outcomes and is the most common indicator for pediatric liver transplantation (LTx). While the mainstay of treatment involves surgically correcting the extrahepatic biliary obstruction via Kasai hepato-portoenterostomy (KHPE), activation of a multitude of biological pathways and yet-to-be-determined etiology in BA continue to foster liver inflammation, cirrhosis and need for LTx. However, important caveats still exist in our understandings of the biliary pathophysiology, the rapidity of liver fibrosis and progression to liver failure, largely due to limited knowledge of the triggers of biliary injury and the inability to accurately model human BA. Although inconclusive, a large body of existing literature points to a potential viral infection in the early peri- or postnatal period as triggers of epithelial injury that perpetuates the downstream biliary disease. Further confounding this issue, are the lack of in-vivo and in-vitro models to efficiently recapitulate the cardinal features of BA, primarily liver fibrosis. To overcome these barriers in BA research, new directions in recent years have enabled (I) identification of additional triggers of biliary injury linked mostly to environmental toxins, (II) development of models to investigate liver fibrogenesis, and (III) translational research using patient-derived organoids. Here, we discuss recent advances that undoubtedly will stimulate future efforts investigating these new and exciting avenues towards mechanistic and drug discovery efforts and disease-preventive measures. The implications of these emerging scientific investigations and disease modeling in severe fibrosing cholangiopathies like BA are enormous and contribute substantially in our understandings of this rare but deadly disease. These findings are also expected to facilitate expeditious identification of translationally targetable pathways and bring us one step closer in treating an infant with BA, a population highly vulnerable to life-long liver related complications.

Regulation of bile duct epithelial injury by hepatic CD71+ erythroid cells

Extramedullary hematopoietic cells are present in the liver of normal neonates in the first few days of life and persist in infants with biliary atresia. Based on a previous report that liver genes are enriched by erythroid pathways, we examined the liver gene expression pattern at diagnosis and found the top 5 enriched pathways are related to erythrocyte pathobiology in children who survived with the native liver beyond 2 years of age. Using immunostaining, anti-CD71 antibodies identified CD71+ erythroid cells among extramedullary hematopoietic cells in the livers at the time of diagnosis. In mechanistic experiments, the preemptive antibody depletion of hepatic CD71+ erythroid cells in neonatal mice rendered them resistant to rhesus rotavirus-induced (RRV-induced) biliary atresia. The depletion of CD71+ erythroid cells increased the number of effector lymphocytes and delayed the RRV infection of livers and extrahepatic bile ducts. In coculture experiments, CD71+ erythroid cells suppressed the activation of hepatic mononuclear cells. These data uncover an immunoregulatory role for CD71+ erythroid cells in the neonatal liver.

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.

Concise Review: Functional Roles and Therapeutic Potentials of Long Non-coding RNAs in Cholangiopathies

Long non-coding RNAs (lncRNAs) are RNAs with lengths exceeding 200 nucleotides that are not translated into proteins. It is well-known that small non-coding RNAs, such as microRNAs (miRNAs), regulate gene expression and play an important role in cholangiopathies. Recent studies have demonstrated that lncRNAs may also play a key role in the pathophysiology of cholangiopathies. Patients with cholangiopathies often develop cholangiocarcinoma (CCA), which is cholangiocyte-derived cancer, in the later stage. Cholangiocytes are a primary target of therapies for cholangiopathies and CCA development. Previous studies have demonstrated that expression levels of lncRNAs are altered in the liver of cholangiopathies or CCA tissues. Some lncRNAs regulate gene expression by inhibiting functions of miRNAs leading to diseased liver conditions or CCA progression, suggesting that lncRNAs could be a novel therapeutic target for those disorders. This review summarizes current understandings of functional roles of lncRNAs in cholangiopathies and seek their potentials for novel therapies.

Preclinical insights into cholangiopathies: disease modeling and emerging therapeutic targets

INTRODUCTION

The common predominant clinical features of cholangiopathies such as primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC), and biliary atresia (BA) are biliary damage/senescence and liver fibrosis. Curative therapies are lacking, and liver transplantation is the only option. An understanding of the mechanisms and pathogenesis is needed to develop novel therapies. Previous studies have developed various disease-based research models and have identified candidate therapeutic targets. Areas covered: This review summarizes recent studies performed in preclinical models of cholangiopathies and the current understanding of the pathophysiology representing potential targets for novel therapies. A literature search was conducted in PubMed using the combination of the searched term 'cholangiopathies' with one or two keywords including 'model', 'cholangiocyte', 'animal', or 'fibrosis'. Papers published within five years were obtained. Expert opinion: Access to appropriate research models is a key challenge in cholangiopathy research; establishing more appropriate models for PBC is an important goal. Several preclinical studies have demonstrated promising results and have led to novel therapeutic approaches, especially for PSC. Further studies on the pathophysiology of PBC and BA are necessary to identify candidate targets. Innovative therapeutic approaches such as stem cell transplantation have been introduced, and those therapies could be applied to PSC, PBC, and BA.