Biliary Atresia as a Disease Starting In Utero: Implications for Treatment, Diagnosis, and Pathogenesis

Disruption of common ocular developmental pathways in patient-derived optic vesicle models of microphthalmia

Genetic perturbations influencing early eye development can result in microphthalmia, anophthalmia, and coloboma (MAC). Over 100 genes are associated with MAC, but little is known about common disease mechanisms. In this study, we generated induced pluripotent stem cell (iPSC)-derived optic vesicles (OVs) from two unrelated microphthalmia patients and healthy controls. At day 20, 35, and 50, microphthalmia patient OV diameters were significantly smaller, recapitulating the "small eye" phenotype. RNA sequencing (RNA-seq) analysis revealed upregulation of apoptosis-initiating and extracellular matrix (ECM) genes at day 20 and 35. Western blot and immunohistochemistry revealed increased expression of lumican, nidogen, and collagen type IV, suggesting ECM overproduction. Increased apoptosis was observed in microphthalmia OVs with reduced phospho-histone 3 (pH3+) cells confirming decreased cell proliferation at day 35. Pharmacological inhibition of caspase-8 activity with Z-IETD-FMK decreased apoptosis in one patient model, highlighting a potential therapeutic approach. These data reveal shared pathophysiological mechanisms contributing to a microphthalmia phenotype.

Pkd1l1-deficiency drives biliary atresia through ciliary dysfunction in biliary epithelial cells

BACKGROUND & AIMS

Syndromic biliary atresia is a cholangiopathy characterized by fibro-obliterative changes in the extrahepatic bile duct (EHBD) and congenital malformations including laterality defects. The etiology remains elusive and faithful animal models are lacking. Genetic syndromes provide important clues regarding the pathogenic mechanisms underlying the disease. We investigated the role of the gene Pkd1l1 in the pathophysiology of syndromic biliary atresia.

METHODS

Constitutive and conditional Pkd1l1 knockout mice were generated to explore genetic pathology as a cause of syndromic biliary atresia. We investigated congenital malformations, EHBD and liver pathology, EHBD gene expression, and biliary epithelial cell turnover. Biliary drainage was functionally assessed with cholangiography. Histology and serum chemistries were assessed after DDC (3,5-diethoxycarbony l-1,4-dihydrocollidine) diet treatment and inhibition of the ciliary signaling effector GLI1.

RESULTS

Pkd1l1-deficient mice exhibited congenital anomalies including malrotation and heterotaxy. Pkd1l1-deficient EHBDs were hypertrophic and fibrotic. Pkd1l1-deficient EHBDs were patent but displayed delayed biliary drainage. Pkd1l1-deficient livers exhibited ductular reaction and periportal fibrosis. After DDC treatment, Pkd1l1-deficient mice exhibited EHBD obstruction and advanced liver fibrosis. Pkd1l1-deficient mice had increased expression of fibrosis and extracellular matrix remodeling genes (Tgfα, Cdkn1a, Hb-egf, Fgfr3, Pdgfc, Mmp12, and Mmp15) and decreased expression of genes mediating ciliary signaling (Gli1, Gli2, Ptch1, and Ptch2). Primary cilia were reduced on biliary epithelial cells and altered expression of ciliogenesis genes occurred in Pkd1l1-deficient mice. Small molecule inhibition of the ciliary signaling effector GLI1 with Gant61 recapitulated Pkd1l1-deficiency.

CONCLUSIONS

Pkd1l1 loss causes both laterality defects and fibro-proliferative EHBD transformation through disrupted ciliary signaling, phenocopying syndromic biliary atresia. Pkd1l1-deficient mice function as an authentic genetic model for study of the pathogenesis of biliary atresia.

IMPACT AND IMPLICATIONS

The syndromic form of biliary atresia is characterized by fibro-obliteration of extrahepatic bile ducts and is often accompanied by laterality defects. The etiology is unknown, but Pkd1l1 was identified as a potential genetic candidate for syndromic biliary atresia. We found that loss of the ciliary gene Pkd1l1 contributes to hepatobiliary pathology in biliary atresia, exhibited by bile duct hypertrophy, reduced biliary drainage, and liver fibrosis in Pkd1l1-deficient mice. Pkd1l1-deficient mice serve as a genetic model of biliary atresia and reveal ciliopathy as an etiology of biliary atresia. This model will help scientists uncover new therapeutic approaches for patients with biliary atresia, while pediatric hepatologists should validate the diagnostic utility of PKD1L1 variants.

Toxins and Biliary Atresia: Is Karenia Brevis (Red Tide) The Culprit?

OBJECTIVE

The study objective was to evaluate the association between Karenia brevis (K. brevis) exposure during pregnancy and the prevalence of biliary atresia (BA) in offspring.

STUDY DESIGN

This was a hospital-based, case-control study in which cases were infants diagnosed with BA at Johns Hopkins All Children's Hospital from October 2001 to December 2019. Cases were matched 1:4 by age to controls who were randomly selected from a pool of healthy infants hospitalized during the study period for common pediatric diagnoses. Infants were excluded if they had congenital anomalies and/or were non-Florida residents. Gestational K. brevis exposure levels (cells/liter) were determined from Florida Fish and Wildlife Conservation Commission exposure data at 10- and 50 mile radii from the mother's zip code of residence. Multivariable conditional logistic regression determined odds of BA in offspring in relation to maternal gestational K. brevis exposure adjusted for infant sex, race/ethnicity, coastal residence, and seasonality.

RESULTS

Of 38 cases and 152 controls, no significant inter-group differences were observed for infant race/ethnicity, season of birth, or coastal residence. Median gestational exposure at the 10 mile radius was 0 cells/liter in both groups. A greater proportion of cases had no gestational K. brevis exposure (63.2 %, n = 24) in comparison to controls (37.5 %, n = 57; p = .04) at a 10 mile radius. At a 50 mile radius, cases had a peak median exposure at 6 months of gestation compared to controls' peak at 9 months. After adjustment for sex, seasonality, race/ethnicity, and coastal residence, there was no significant association between BA and maximum K. brevis exposure per trimester of pregnancy observed at a 10- or 50 mile radius.

CONCLUSION

In this matched case-control study, we observed no association between gestational K. brevis (cells/liter) exposure at a 10- or 50 mile radius from maternal zip code of residence and BA in offspring.

Pediatric Cholestatic Diseases: Common and Unique Pathogenic Mechanisms

Cholestasis is the predominate feature of many pediatric hepatobiliary diseases. The physiologic flow of bile requires multiple complex processes working in concert. Bile acid (BA) synthesis and excretion, the formation and flow of bile, and the enterohepatic reuptake of BAs all function to maintain the circulation of BAs, a key molecule in lipid digestion, metabolic and cellular signaling, and, as discussed in the review, a crucial mediator in the pathogenesis of cholestasis. Disruption of one or several of these steps can result in the accumulation of toxic BAs in bile ducts and hepatocytes leading to inflammation, fibrosis, and, over time, biliary and hepatic cirrhosis. Biliary atresia, progressive familial intrahepatic cholestasis, primary sclerosing cholangitis, and Alagille syndrome are four of the most common pediatric cholestatic conditions. Through understanding the commonalities and differences in these diseases, the important cellular mechanistic underpinnings of cholestasis can be greater appreciated.

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.

Genetic Contributions to Biliary Atresia: A Developmental Cholangiopathy

Biliary atresia (BA) is the most prevalent serious liver disease of infancy and childhood, and the principal indication for liver transplantation in pediatrics. BA is best considered as an idiopathic panbiliary cholangiopathy characterized by obstruction of bile flow and consequent cholestasis presenting during fetal and perinatal periods. While several etiologies have been proposed, each has significant drawbacks that have limited understanding of disease progression and the development of effective treatments. Recently, modern genetic analyses have uncovered gene variants contributing to BA, thereby shifting the paradigm for explaining the BA phenotype from an acquired etiology (e.g., virus, toxin) to one that results from genetically altered cholangiocyte development and function. Herein we review recently reported genetic contributions to BA, highlighting the enhanced representation of variants in biological pathways involving ciliary function, cytoskeletal structure, and inflammation. Finally, we blend these findings as a new framework for understanding the resultant BA phenotype as a developmental cholangiopathy.

Opportunities and considerations for studying liver disease with microphysiological systems on a chip

Advances in microsystem engineering have enabled the development of highly controlled models of the liver that better recapitulate the unique in vivo biological conditions. In just a few short years, substantial progress has been made in creating complex mono- and multi-cellular models that mimic key metabolic, structural, and oxygen gradients crucial for liver function. Here we review: 1) the state-of-the-art in liver-centric microphysiological systems and 2) the array of liver diseases and pressing biological and therapeutic challenges which could be investigated with these systems. The engineering community has unique opportunities to innovate with new liver-on-a-chip devices and partner with biomedical researchers to usher in a new era of understanding of the molecular and cellular contributors to liver diseases and identify and test rational therapeutic modalities.

Liver-restricted deletion of the biliary atresia candidate gene Pkd1l1 causes bile duct dysmorphogenesis and ciliopathy

BACKGROUND AND AIMS

A recent multicenter genetic exploration of the biliary atresia splenic malformation syndrome identified mutations in the ciliary gene PKD1L1 as candidate etiologic contributors. We hypothesized that deletion of Pkd1l1 in developing hepatoblasts would lead to cholangiopathy in mice.

APPROACH AND RESULTS

CRISPR-based genome editing inserted loxP sites flanking exon 8 of the murine Pkd1l1 gene. Pkd1l1Fl/Fl cross-bred with alpha-fetoprotein-Cre expressing mice to generate a liver-specific intrahepatic Pkd1l1 -deficient model (LKO). From embryonic day 18 through week 30, control ( Fl/Fl ) and LKO mice were evaluated with standard serum chemistries and liver histology. At select ages, tissues were analyzed using RNA sequencing, immunofluorescence, and electron microscopy with a focus on biliary structures, peribiliary inflammation, and fibrosis. Bile duct ligation for 5 days of Fl/Fl and LKO mice was followed by standard serum and liver analytics. Histological analyses from perinatal ages revealed delayed biliary maturation and reduced primary cilia, with progressive cholangiocyte proliferation, peribiliary fibroinflammation, and arterial hypertrophy evident in 7- to 16-week-old LKO versus Fl/Fl livers. Following bile duct ligation, cholangiocyte proliferation, peribiliary fibroinflammation, and necrosis were increased in LKO compared with Fl/Fl livers.

CONCLUSIONS

Bile duct ligation of the Pkd1l1 -deficient mouse model mirrors several aspects of the intrahepatic pathophysiology of biliary atresia in humans including bile duct dysmorphogenesis, peribiliary fibroinflammation, hepatic arteriopathy, and ciliopathy. This first genetically linked model of biliary atresia, the Pkd1l1 LKO mouse, may allow researchers a means to develop a deeper understanding of the pathophysiology of this serious and perplexing disorder, including the opportunity to identify rational therapeutic targets.

A Pilot Study of Biliary Atresia Newborn Screening Using Dried Blood Spot Matrix Metalloproteinase-7

OBJECTIVES

Timely diagnosis is a critical challenge and is associated with improved survival of biliary atresia (BA) patients. We aimed to measure matrix metalloproteinase-7 (MMP-7) levels in BA patients within 3 days of birth using the dried blood spot (DBS) method and evaluate its potential as a screening tool.

METHODS

The study enrolled 132 patients, including 25 patients diagnosed with BA and 107 non-BA patients with other congenital or perinatal conditions from the National Taiwan University Children Hospital. The stored DBS samples collected from 48 to 72 hours of life were retrieved from newborn screening centers. MMP-7 on the DBS was quantified using a sensitive sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

The MMP-7 levels of BA patients on the DBS were significantly higher than those of non-BA patients (19.2 ± 10.4 vs 5.6 ± 2.7 ng/mL, P value < 0.0001). MMP-7 levels in non-BA patients, including 5 patients with hepatobiliary structural anomaly, 9 patients with intrahepatic cholestasis, and 93 patients with other perinatal diseases, were 11.6 ± 4.2 ng/mL, 6.9 ± 3.0 ng/mL, and 5.2 ± 2.1 ng/mL, respectively. The DBS MMP-7 level showed good accuracy for identifying BA, with an area under the curve of 93.7% [95% confidence interval (CI): 87.7%-99.7%]. The MMP-7 cutoff at 8.0 ng/mL showed a sensitivity of 92.0% (95% CI: 75.0%-98.6%) and specificity of 92.5% (95% CI: 85.9%-96.1%) for detecting BA from other congenital or perinatal diseases.

CONCLUSIONS

MMP-7 DBS analysis can be used to distinguish BA from other conditions as early as 3 days of age.

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.

Biliary Atresia Remnants Revisited: Myogenesis, Hepatic Duct-Like Structures, and Fate of Peribiliary Glands

PURPOSE AND CONTEXT

Proximal levels of excised remnants from youngest infants may reveal early features of biliary atresia (BA).

METHOD

A targeted IHC survey was applied to 34 most proximal 2 levels in 17 BA remnants excised at age 10-74 days including 7 = <30 days old and 6 control hepatic ducts (HD).

KEY RESULTS

Severity of inflammation and extent of active fibroplasia do not distinguish proximal remnants in younger (n = 7) and older (n = 10) infants. In 27/34 levels of 14/17 remnants, reactive stroma is focally SM-MHC-2 (+), marking smooth muscle myosin, termed reactive myogenesis (RM), that is absent in controls. RM facilitates identification of 3 novel hepatic duct remnants (HDR): an HD-like collagen collar lined by degenerating cholangiocytes (n = 5); erosion defects in loose reactive stroma (n = 14); solitary foci of hyperplastic squamoid epithelium (n = 4). Peribiliary glands are either hyperplastic or atretic and typically lack RM.

CONCLUSION

Minimally inflammed end-stage lesions in BA remnants occur at youngest ages favoring prenatal onset. Three novel HDR are defined. RM, a useful surrogate for HDR, is a prevalent inappropriate stromal reaction in proximal remnants of uncertain biological significance. RM is the source of mature smooth muscle in BA remnants.

Native liver survivors of portoenterostomy for biliary atresia with excellent outcome: redefining "successful" portoenterostomy

PURPOSE

Native liver survivors (NLS) after portoenterostomy (PE) for biliary atresia (BA) with normal biomarkers defined as total bilirubin (T-Bil), aspartate aminotransferase (AST)/alanine aminotransferase (ALT) for liver function (LF), cholinesterase (ChE), platelet count (PC), and absence of portal hypertension (PHT) were reviewed to redefine "successful" PE.

METHODS

92 post-PE BA patients were classified as NLS-1: normal biomarkers, PHT (-); NLS-2: at least one abnormal biomarker, PHT (-); NLS-3: normal biomarkers, PHT ( +); NLS-4: abnormal biomarkers, PHT ( +) and reviewed for a maximum 32 years.

RESULTS

As of June 2022, 55/92 (59.8%) had received liver transplants and 37/92 (40.2%) were NLS. NLS patients were classified as excellent outcome (EO): NLS-1 (n = 10; 27.0%) or non-EO: NLS-2: (n = 8; 21.6%), NLS-3: (n = 6; 16.2%), and NLS-4: (n = 13; 35.1%). Compared with non-EO, EO had PE earlier (50.5 versus 65 days; not significant; p = 0.08), significantly earlier onset of symptoms (13 days versus 32 days; p = 0.01) and significantly shorter jaundice-clearance (JC; 34.5 days versus 56.0 days; p < 0.001). Durations of follow-up were similar: 13 years in EO, 18.5 years in NLS-2, 20 years in NLS-3, and 15 years in NLS-4.

CONCLUSION

Incidence of "successful" PE or EO is low and correlated with early onset of symptoms and quicker JC.

Protocols of Investigation of Neonatal Cholestasis-A Critical Appraisal

Neonatal cholestasis (NC) starts during the first three months of life and comprises extrahepatic and intrahepatic groups of diseases, some of which have high morbimortality rates if not timely identified and treated. Prolonged jaundice, clay-colored or acholic stools, and choluria in an infant indicate the urgent need to investigate the presence of NC, and thenceforth the differential diagnosis of extra- and intrahepatic causes of NC. The differential diagnosis of NC is a laborious process demanding the accurate exclusion of a wide range of diseases, through the skillful use and interpretation of several diagnostic tests. A wise integration of clinical-laboratory, histopathological, molecular, and genetic evaluations is imperative, employing extensive knowledge about each evaluated disease as well as the pitfalls of each diagnostic test. Here, we review the difficulties involved in correctly diagnosing the cause of cholestasis in an affected infant.

Biliary Atresia in Children: Update on Disease Mechanism, Therapies, and Patient Outcomes

Biliary atresia is a rare disease but remains the most common indication for pediatric liver transplantation as there are no effective medical therapies to slow progression after diagnosis. Variable contribution of genetic, immune, and environmental factors contributes to disease heterogeneity among patients with biliary atresia. Developing a deeper understanding of the disease mechanism will help to develop targeted medical therapies and improve patient outcomes.

Rare spontaneous monochorionic dizygotic twins: a case report and a systematic review

BACKGROUND

Monochorionic dizygotic twins are a rare condition, mostly related to assisted reproductive technology. This type of twinning is burdened by the same risk of pregnancy complications found in monochorionic monozygotic pregnancies.

CASE PRESENTATION

We report a case of spontaneous monochorionic dizygotic twins sharing situs inversus abdominalis and isolated levocardia, with only one twin affected by biliary atresia with splenic malformation syndrome. We also conducted a literature review of the 14 available documented monochorionic dizygotic twin gestations spontaneously conceived.

CONCLUSIONS

It is still unclear how this unusual type of twinning can occur in spontaneous conception. The evidence so far suggest the importance to timely diagnose the chorionicity, in order to adequately manage the typical complications associated with monochorionicity.

The Epidemiology of Biliary Atresia: Exploring the Role of Developmental Factors on Birth Prevalence

OBJECTIVE

To identify key epidemiologic factors relevant to fetal development that are associated with biliary atresia.

STUDY DESIGN

This population-based registry study examined infants born in Texas between 1999 and 2014. Epidemiologic data relevant to fetal development were compared between cases of biliary atresia identified in the Texas Birth Defects Registry (n = 305) vs all live births (n = 4 689 920), and Poisson regression was used to calculate prevalence ratios (PRs) and 95% CIs.

RESULTS

The prevalence of biliary atresia over the study period was 0.65 per 10 000 live births. Biliary atresia was positively associated with female sex (adjusted PR, 1.68; 95% CI, 1.33-2.12), delivery before 32-37 weeks of gestation (adjusted PR, 1.64; 95% CI, 1.18-2.29), delivery before 32 weeks of gestation (adjusted PR, 3.85; 95% CI, 2.38-6.22), and non-Hispanic Black vs non-Hispanic White maternal race/ethnicity (adjusted PR, 1.54, 95% CI, 1.06-2.24), while biliary atresia was inversely associated with season of conception in the fall relative to spring (adjusted PR, 0.62; 95% CI, 0.45-0.86). In addition, biliary atresia was associated with maternal diabetes (adjusted PR, 2.34; 95% CI, 1.57-3.48), with a stronger association with pregestational diabetes compared with gestational diabetes. In subgroup analyses, these associations were present in isolated biliary atresia cases that do not have any additional birth defects.

CONCLUSIONS

Biliary atresia is associated with multiple factors related to fetal development, including pregestational maternal diabetes, female sex, and preterm birth. These associations also were observed in isolated cases of biliary atresia without other malformations or laterality defects. Our results are consistent with early life events influencing the pathogenesis of biliary atresia, and support further studies investigating in utero events to better understand etiology and time of onset.

The Epidemiology and Outcome of Biliary Atresia: Saudi Arabian National Study (2000-2018)

BACKGROUND

The epidemiology and outcomes of biliary atresia (BA) have been well-documented in national cohorts from two main ethnicities, namely, the Asian Orientals and Caucasians, with incidence ranging from 1 in 5,000 to 1 in 9,000 live births in East Asia and 1 in 15,000 to 19,000 live births in Europe and North America.

OBJECTIVE

We report the first nationwide BA study outside North America, Europe, and East Asia to describe the epidemiology and outcomes of BA in Saudi Arabia.

METHODS

A national database of BA cases diagnosed between 2000 and 2018 was analyzed. We assessed clearance of jaundice (bilirubin <20 μmol/L) in all cases that underwent Kasai portoenterostomy (KPE). We then estimated survival using the Kaplan-Meier method with endpoints of liver transplantation (LT), death, or survival with native liver (SNL).

RESULTS

BA was diagnosed in 204 infants (106 females; 10% pre-term). The incidence of BA was 1 in 44,365, or 2.254 in 100,000 live births (range, 0.5-4 in 100,000). Polysplenia was diagnosed in 22 cases (11%). The median age at referral was 65 days. A total of 146 children (71.5%) underwent KPE at a median age of 70 days. Clearance of jaundice was achieved in 66 of the 146 (45%) infants. The 10-year SNL after KPE was 25.5%, and the overall 10-year estimated survival was 72.5%. The Kaplan-Meier survival curves for patients undergoing KPE at the age of <60, 61-90, and >90 days showed a SNL rate at 51.6, 33, and 12.5%, respectively, at 5 years (P < 0.001). The 2-, 5-, and 10-year post-LT survival rates were 92.5, 90.6, and 90%, respectively. Undergoing an initial KPE did not impact negatively on the overall LT survival rate when compared to BA cases that underwent primary LT (P = 0.88).

CONCLUSION

The incidence rate of BA in Saudi Arabia is lower than the incidence reported elsewhere. Late referral of BA cases remains a problem in Saudi Arabia; as a result, the SNL rate was lower than reported by other national registries. Hence, national policies devoted to timely referral and earlier age at KPE are needed.

Low gamma-glutamyl transpeptidase levels at presentation are associated with severity of liver illness and poor outcome in biliary atresia

OBJECTIVE

To investigate the clinical features and prognosis of biliary atresia (BA) with normal or minimally elevated gamma-glutamyl transpeptidase (GGT).

METHODS

The clinical data of patients with BA in our hospital between 2012 and 2017 were retrospectively studied. The patients were divided into a low-GGT group (GGT ≤ 300 IU/L) and a high-GGT group (GGT > 300 IU/L) according to the preoperative GGT level. The perioperative clinical parameters, the postoperative jaundice clearance within 6 months, and the 2-year native liver survival were compared among the groups.

RESULTS

A total of 1,998 children were included in this study, namely, 496 in the low-GGT group and 1,502 in the high-GGT group. The ages and weights at the surgery in the low-GGT group were significantly lower than those in the high-GGT group (64.71 ± 21.35 vs. 68.64 ± 22.42 days, P = 0.001; 4.67 ± 1.03 vs. 4.89 ± 0.98 kg, P < 0.001). The levels of serum ALP, ALT, and AST in the low-GGT group were significantly higher than those in the high-GGT group before and 2 weeks after the surgery (ALP: 647.52 ± 244.10 vs. 594.14 ± 228.33 U/L, P < 0.001; ALT: 119.62 ± 97.14 vs. 96.01 ± 66.28 U/L, P < 0.001; AST: 218.00 ± 173.82 vs. 160.71 ± 96.32 U/L; P < 0.001). The INR of the low-GGT group was higher than that of the high-GGT group (1.05 ± 0.34 vs. 0.98 ± 0.20, P < 0.001), while FIB was lower than the high-GGT group (2.54 ± 0.67 vs. 2.73 ± 1.44 g/L; P = 0.006). The decreasing amplitude of TB and DB within 2 weeks after surgery in the low-GGT group was smaller than those in the high-GGT group (TB: 51.62 ± 71.22 vs. 61.67 ± 53.99 μmol/L, P = 0.003; DB: 33.22 ± 35.57 vs. 40.20 ± 35.93 μmol/L, P < 0.001). The jaundice clearance rate in the low-GGT group was significantly lower than that in the high-GGT group at 1, 3, and 6 months after surgery (17.70 vs. 26.05%; 35.17 vs. 48.58%; 38.62 vs. 54.64%, P < 0.001). In addition, the 2-year native liver survival rate in the low-GGT group was significantly lower than that of the high-GGT group (52.5 vs. 66.3%, P < 0.001 HR 1.80, 95% CI 1.38-2.33).

CONCLUSION

Compared to patients with high GGT, patients with normal or minimally elevated pre-operative GGT in BA were found to have poorer pre-operative liver function parameters, and post-operatively had lower jaundice clearance rates and worse 2-year native liver survival. This suggests a lower GGT at presentation in biliary atresia could be a sign of more severe liver injury.

Re-evaluation of Laparoscopic Hepatic Subcapsular Spider-Like Telangiectasis Sign: A Highly Accurate Method to Diagnose Biliary Atresia in Infants

OBJECTIVE

Operative cholangiography, the gold standard for the diagnosis of biliary atresia (BA), is being challenged due to an increase in the studies of misdiagnosis. A previous study has shown that the laparoscopic hepatic subcapsular spider-like telangiectasis (HSST) sign was accurate for diagnosing BA. This study aims to compare the performance of the HSST sign with cholangiography in the identification of BA.

METHODS

We prospectively screened consecutive infants with cholestasis who underwent laparoscopic exploration in this multicenter study. Demographics, intraoperative findings (videos and images), and outcomes were retrospectively analyzed. The data of the HSST sign and cholangiography were compared according to the final diagnosis. Then, the diagnostic accuracy of the BA using the HSST sign and cholangiography was validated in other independent cohorts.

RESULTS

A total of 2,216 patients were enrolled in this study. The sensitivity and negative predictive values were both 100% for diagnosing BA based on the HSST sign and cholangiography. The specificity, negative predictive value, and accuracy of the HSST sign (97.2, 99.2, 99.3%) in discriminating BA were significantly higher than operative cholangiography (81.6, 94.9, 95.8; p < 0.001). Moreover, to realize the early diagnosis of BA, the accuracy of the HSST sign in identifying BA was better than cholangiography in the subgroup of neonates (98.7% vs. 95.0%; p = 0.032). Interestingly, 92 non-BA patients without the HSST sign had positive cholangiography. Among them, 28 infants had negative cholangiography when the common bile duct was compressed and 39 patients displayed visible bile ducts due to repeated postoperative biliary irrigation. The other 25 patients (18 with the Alagille syndrome, 5 with progressive familial intrahepatic cholestasis, and 2 with the neonatal hepatitis syndrome) had consistently positive cholangiography. In the independent validation cohort, the diagnostic accuracy of the HSST sign (99.2%) was higher than cholangiography (95.0%, p = 0.012).

CONCLUSION

The laparoscopic HSST sign is superior to cholangiography in the diagnosis of BA in the infants with cholestasis and has advantages in early diagnosis. This method is expected to become a novel shift for diagnosing BA during ongoing laparoscopy.

Biliary Atresia: Clinical Phenotypes and Aetiological Heterogeneity

Biliary atresia (BA) is an obliterative condition of the biliary tract that presents with persistent jaundice and pale stools typically in the first few weeks of life. While this phenotypic signature may be broadly similar by the time of presentation, it is likely that this is only the final common pathway with a number of possible preceding causative factors and disparate pathogenic mechanisms-i.e., aetiological heterogeneity. Certainly, there are distinguishable variants which suggest a higher degree of aetiological homogeneity such as the syndromic variants of biliary atresia splenic malformation or cat-eye syndrome, which implicate an early developmental mechanism. In others, the presence of synchronous viral infection also make this plausible as an aetiological agent though it is likely that disease onset is from the perinatal period. In the majority of cases, currently termed isolated BA, there are still too few clues as to aetiology or indeed pathogenesis.

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."

Newborn Screening for Biliary Atresia: a Review of Current Methods

PURPOSE OF REVIEW

Biliary atresia is a serious neonatal liver disease due to obstructed bile ducts that has better outcomes when detected and treated in the first 30-45 days of life. This review examines different methods to screen newborns for biliary atresia as well as discusses observations from ongoing screening programs implemented in parts of the United States.

RECENT FINDINGS

Screening strategies for biliary atresia include detecting persistent jaundice, examining stool color, testing fractionated bilirubin levels, or measuring bile acid levels from dried blood spot cards. The stool color card program is the most widely used screening strategy worldwide. An alternative approach under investigation in the United States measures fractionated bilirubin levels, which are abnormal in newborns with biliary atresia. Fractionated bilirubin screening programs require laboratories to derive reference ranges, nurseries to implement universal testing, and healthcare systems to develop infrastructure that identifies and acts upon abnormal results. Biliary atresia meets the disease-specific criteria for newborn screening. Current studies focus on developing a strategy which also meets all test-specific criteria. Such a strategy, if implemented uniformly, has the potential to accelerate treatment and reduce biliary atresia's large liver transplant burden.

Developmental histology of the portal plate in biliary atresia: observations and implications

PURPOSE

The key characteristic of biliary atresia (BA) is obliteration of the extrahepatic bile ducts at the level of the porta hepatis. We aimed to relate the immunohistochemical features of remnant biliary ductules at the porta hepatis with clinical features and outcomes.

METHODS

Samples were immunostained with anti-cytokeratin 20 (CK20), vimentin and alpha-smooth muscle actin (aSMA). Primary outcome was set as clearance of jaundice (bilirubin ≤ 20 μmol/L) following Kasai portoenterostomy (KPE).

RESULTS

Eighty-two cases were classified into syndromic BA (n = 10), cystic BA (n = 7), CMV IgM+ BA (n = 9) and isolated BA (n = 56). CK20 expression was confirmed in 40/82 (49%), and vimentin expression in 19/82 (23%). aSMA was negative in all cases studied. CK20 expression was less common in isolated BA (n = 20/56, 36%) compared to CMV IgM+ BA (n = 8/9, 89%), cystic BA (n = 7/7, 100%) (isolated BA vs non-isolated BA, P = 0.0008). There was no difference in vimentin expression among the sub-groups (isolated BA vs. non-isolated BA; P = 0.39). CoJ was achieved in 52/82 (63%) overall with significant difference depending simply on sub-group [e.g. syndromic BA 9/10 (90%)]. CK20 expression was associated with a diminished rate of CoJ in the entire cohort [CK20+ 32/56 (57%) vs. CK20- 20/26 (77%); P = 0.04]. By contrast no correlation was observed between vimentin expression and CoJ (P = 0.13).

CONCLUSION

CK20+ expression was associated with reduced clearance of jaundice in BA and a trend towards reduced native liver survival.

Cost-Effectiveness of Primary Liver Transplantation Versus Hepatoportoenterostomy in the Management of Biliary Atresia in the United States

Biliary atresia (BA) is the leading indication to perform a pediatric liver transplantation (LT). Timely hepatoportoenterostomy (HPE) attempts to interrupt the natural history and allow for enteric bile flow; however, most patients who are treated with HPE require LT by the age of 10 years. We determined the cost-effectiveness of foregoing HPE to perform primary LT (pLT) in children with BA compared with standard-of-care HPE management. A Markov model was developed to simulate BA treatment over 10 years. Costs were measured in 2018 US dollars and effectiveness in life-years (LYs). The primary outcome was incremental cost-effectiveness ratio (ICER) between treatments. Model parameters were derived from the literature. In the base model, we assumed similar LT outcomes after HPE and pLT. Sensitivity analyses on all model parameters were performed, including a scenario in which pLT led to 100% patient and graft survival after LT. Children undergoing HPE accumulated $316,692 in costs and 8.17 LYs per patient. Children undergoing pLT accumulated $458,059 in costs and 8.24 LYs per patient, costing $1,869,164 per LY gained compared with HPE. With parameter variation over plausible ranges, only post-HPE and post-LT costs reduced the ICER below a typical threshold of $100,000 per LY gained. On probabilistic sensitivity analysis, 93% of iterations favored HPE at that threshold. With 100% patient and graft survival after pLT, pLT cost $283,478 per LY gained. HPE is more economically favorable than pLT for BA. pLT is unfavorable even with no graft or patient loss. The ability to predict those patients who may experience high costs after HPE or low costs after LT may help identify those patients for whom pLT could be considered.

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.

Deletion of interleukin enhancer binding factor 2 (ILF2) resulted in defective biliary development and bile flow blockage

PURPOSE

Biliary atresia (BA) is a devastating obstructive bile duct disease of newborns. BA has the highest incidence in Asians (1/5000), and its pathogenesis is unclear. We identified BA-private rare copy number variants (CNVs; 22 duplications and 6 deletions). ILF2 gene locates in the chromosome region (Chr1:153410347-153,634,058) which was deleted in a nonsyndromic BA patient. However, it is still not known whether ILF2 plays a role in hepatobiliary development and its deletion impacts on the bile duct development.

METHODS

To investigate if ILF2 is required for biliary development, we knock-out the zebrafish homologs of ILF2 by CRISPR/Cas9 approach, and discover that deletion of ILF2 causes a defective biliary development and a lack of bile flow from the liver to the gall bladder in zebrafish, which is a resemblance of phenotypes of BA.

RESULTS

Our data indicate that ILF2 gene is required for biliary development; deletion of ILF2 impairs bile duct development and could contribute to BA pathogenesis. This will be the first study to functionally evaluate the genes interfered by BA-private CNVs in hepatobiliary development and in BA pathogenesis.

CONCLUSIONS

Such functional study may reveal the potential value of these BA-private CNVs in the disease pathogenesis for BA.

LEVEL OF EVIDENCE

N/A (animal and laboratory study).

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.

Body Composition of Infants With Biliary Atresia: Anthropometric Measurements and Computed Tomography-based Body Metrics

OBJECTIVES

Biliary atresia (BA) causes neonatal cholestasis that requires hepatoportoenterostomy or liver transplantation (LT) for long-term survival. Nutritional optimization is necessary as sarcopenia and sarcopenic obesity have been associated with adverse clinical outcome. Currently, mid upper arm circumference (MUAC) is considered the most accurate indicator. The aim of the study was to determine computed tomography (CT)-based body metrics in infants with BA and to evaluate its correlation with MUAC.

METHODS

We retrospectively analyzed all BA infants below 2 years of age who underwent CT as part of LT screening at our hospital between 2006 and 2019. Measured variables were indexed with length and included: MUAC, total psoas muscle surface area (tPMSA), cross-sectional skeletal muscle area (CSMA), and total abdominal fat area. Intraclass correlation coefficients and Pearson coefficients were calculated. CSMA-to-abdominal fat area ratio was divided in quartiles, the lowest quartile group was considered sarcopenic obese.

RESULTS

Eighty infants with a median age of 4.6 months at LT screening were included. Intraclass correlation coefficients were: tPMSA = 0.94, CSMA = 0.92, and total abdominal fat area = 0.99. Correlation between MUAC z-score and indices of tPMSA, CSMA, and total abdominal fat area were r = 0.02, r = 0.06, and r = 0.43, respectively. The cut-off for sarcopenic obesity was CSMA-to-abdominal fat area ratio below 0.93.

CONCLUSIONS

In BA infants, it is possible to determine CT-based body metrics during LT screening with very strong interobserver agreement. Poor correlation between CT-based body metrics and MUAC suggests that CT-based body metrics provide additional information on body composition in BA infants, such as relative muscle mass.

Biliary atresia: Potential for a new decade

Biliary atresia is characterised as an obliterative cholangiopathy of both extra-and intra-hepatic bile ducts. There is marked aetiological heterogeneity with a number of different variants, some syndromic and others perhaps virally-mediated. Current research aims to try and define possible mechanisms and pathogenesis though an actual breakthrough remains elusive. There has been little in the way of surgical advances beyond subtle variations in the Kasai portoenterostomy and laparoscopic equivalents have no declared advantage and have yet to prove equivalence in measures of outcome. The next target has been to maximise potential with better adjuvant therapy, though the evidence base for most currently available therapies such as steroids and ursodeoxycholic acid remains limited. Still high-dose steroid use is widespread, certainly in Europe and the Far East. Clearance of jaundice can be achieved in 50-60% of those subjected to portoenterostomy at <70 days and should be an achievable benchmark. Transplantation is a widely available "rescue" therapy though whether it should be an alternative as a primary procedure is arguable but becoming increasingly heard. The aim of clinical practice remains to get these infants for surgery as early as is possible though this can be difficult to accomplish in practice, and "low-cost" screening projects using stool colour charts have been limited outside of Taiwan and Japan. Centralisation of resources (medical and surgical) is associated with a diminution of time to portoenterostomy but application has been limited by entrenched health delivery models or geographical constraints.

Natural history, risk factors, and outcome of hepatopulmonary syndrome in pediatric liver diseases

BACKGROUND

Limited pediatric literature is available regarding hepatopulmonary syndrome (HPS) especially in subjects with biliary atresia (BA) despite its proven prognostic significance. Thus, we aimed to study the natural history, risk factors, and outcome of HPS in BA and other chronic liver disease (CLD) subjects.

METHODS

All children (BA and other non-BA CLDs) older than 6 months of age were included in the study. HPS was diagnosed on the basis of standard international criteria. Also, fractional exhaled nitric oxide (FeNO) was measured at baseline.

RESULTS

During the study period from January 2017 to December 2018, there were 42 children in BA and 62 in the CLD group. The overall prevalence of HPS was 42.3%: 57.1% in the BA group and 32.2% in the CLD group. Median age at HPS diagnosis was 14.4 months and 90 months in the BA and non-BA CLD groups, respectively. By the end of study period, the prevalence of HPS in the BA group further increased to 73.8% at 0.7% per month. Lower serum albumin (p < 0.05) in BA and higher splenic Z scores (p 0.013) in other CLDs were found to be significant risk factors for HPS. FeNO measurement did not reach diagnostic significance.

CONCLUSION

Prevalence of HPS is higher and also develops at an earlier age in the BA group compared to other CLDs. Also, risk of HPS development increases with increasing disease duration in BA. Lower serum albumin in BA and higher splenic Z scores in other CLDs may predict risk for HPS development.