Recent advances in understanding biliary atresia

Integrative single-cell and spatial transcriptomic analyses identify a pathogenic cholangiocyte niche and TNFRSF12A as therapeutic target for biliary atresia

BACKGROUND AND AIMS

Biliary atresia (BA) is a devastating fibroinflammatory biliary disease that is the leading indication for pediatric liver transplants worldwide. Although cholangiocytes are the primary target cells, the pathogenic mechanisms involving cholangiocytes remain elusive. Here, we aimed to characterize the pathogenic role of cholangiocytes in BA.

APPROACH AND RESULTS

Integration of single-cell RNA sequencing of 12 liver tissues (from 9 BA and 3 controls) and the spatial transcriptome of another four liver sections (from 2 BA and 2 controls) provided a comprehensive spatial liver cell atlas of BA. In particular, we identified a cholangiocyte-enriched spatial niche with infiltration of activated HSCs, activated portal fibroblasts, macrovascular endothelial cells, and TREM2 + macrophages that were elevated in the portal triad of BA. This niche was positively correlated with bile duct profiles, liver fibrosis, and poor survival in 2 independent cohorts of patients with BA. Using integrative bioinformatics analyses to mine the cell-cell communication and regulatory network in BA cholangiocytes, we uncovered the fibroinflammatory phenotype of cholangiocytes with TNFSF12-TNFRSF12A as a significant signal. Genetic ablation or blockade of TNFRSF12A suppresses liver injury, inflammation, and bile duct profiles in a mouse model of disease. Using human biliary organoids, we revealed that BA organoids expressed higher levels of CCL2 in response to TNFSF12 stimulation and promoted monocyte chemotaxis via the CCL2-CCR2 axis.

CONCLUSIONS

Pathogenic cholangiocytes-enriched niche identifies TNFRSF12A as a potential therapeutic target for BA.

Positive autoregulation of Sox17 is necessary for gallbladder and extrahepatic bile duct formation

Expression of SRY-box transcription factor 17 (Sox17) in the endodermal region caudal to the hepatic diverticulum during late gastrulation is necessary for hepato-pancreato-biliary system formation. Analysis of an allelic series of promoter-proximal mutations near the transcription start site (TSS) 2 of Sox17 in mouse has revealed that gallbladder (GB) and extrahepatic bile duct (EHBD) development is exquisitely sensitive to Sox17 expression levels. Deletion of a SOX17-binding cis-regulatory element in the TSS2 promoter impairs GB and EHBD development by reducing outgrowth of the nascent biliary bud. These findings reveal the existence of a SOX17-dependent autoregulatory loop that drives Sox17 expression above a critical threshold concentration necessary for GB and EHBD development to occur, and that minor impairments in Sox17 gene expression are sufficient to impair the expression of SOX17-regulated genes in the nascent GB and EHBD system, impairing or preventing development.

Accurate prediction of biliary atresia with an integrated model using MMP-7 levels and bile acids

BACKGROUND

Biliary atresia (BA) is a rare fatal liver disease in children, and the aim of this study was to develop a method to diagnose BA early.

METHODS

We determined serum levels of matrix metalloproteinase-7 (MMP-7), the results of 13 liver tests, and the levels of 20 bile acids, and integrated computational models were constructed to diagnose BA.

RESULTS

Our findings demonstrated that MMP-7 expression levels, as well as the results of four liver tests and levels of ten bile acids, were significantly different between 86 BA and 59 non-BA patients (P < 0.05). The computational prediction model revealed that MMP-7 levels alone had a higher predictive accuracy [area under the receiver operating characteristic curve (AUC) = 0.966, 95% confidence interval (CI): 0.942, 0.989] than liver test results and bile acid levels. The AUC was 0.890 (95% CI 0.837, 0.943) for liver test results and 0.825 (95% CI 0.758, 0.892) for bile acid levels. Furthermore, bile levels had a higher contribution to enhancing the predictive accuracy of MMP-7 levels (AUC = 0.976, 95% CI 0.953, 1.000) than liver test results. The AUC was 0.983 (95% CI 0.962, 1.000) for MMP-7 levels combined with liver test results and bile acid levels. In addition, we found that MMP-7 levels were highly correlated with gamma-glutamyl transferase levels and the liver fibrosis score.

CONCLUSION

The innovative integrated models based on a large number of indicators provide a noninvasive and cost-effective approach for accurately diagnosing BA in children. Video Abstract (MP4 142103 KB).

In Utero Extrahepatic Bile Duct Damage and Repair: Implications for Biliary Atresia

Biliary atresia (BA) is a cholangiopathy affecting the extrahepatic bile duct (EHBD) of newborns. The etiology and pathophysiology of BA are not fully understood; however, multiple causes of damage and obstruction of the neonatal EHBD have been identified. Initial damage to the EHBD likely occurs before birth. We discuss how different developmental stages in utero and birth itself could influence the susceptibility of the fetal EHBD to damage and a damaging wound-healing response. We propose that a damage-repair response of the fetal and neonatal EHBD involving redox stress and a program of fetal wound healing could-regardless of the cause of the initial damage-lead to either obstruction and BA or repair of the duct and recovery. This overarching concept should guide future research targeted toward identification of factors that contribute to recovery as opposed to progression of injury and fibrosis. Viewing BA through the lens of an in utero damage-repair response could open up new avenues for research and suggests exciting new therapeutic targets.

Hsa_circ_0009096/miR-370-3p modulates hepatic stellate cell proliferation and fibrosis during biliary atresia pathogenesis

Background

Hepatic stellate cell (HSC) activation and hepatic fibrosis mediated biliary atresia (BA) development, but the underlying molecular mechanisms are poorly understood. This study aimed to investigate the roles of circRNA hsa_circ_0009096 in the regulation of HSC proliferation and hepatic fibrosis.

Methods

A cellular hepatic fibrosis model was established by treating LX-2 cells with transforming growth factor β (TGF-β1). RNaseR and actinomycin D assays were performed to detect hsa_circ_0009096 stability. Expression of hsa_circ_0009096, miR-370-3p, and target genes was detected using reverse transcription-qPCR. Direct binding of hsa_circ_0009096 to miR-370-3p was validated using dual luciferase reporter assay. Cell cycle progression and apoptosis of LX-2 cells were assessed using flow cytometry. The alpha-smooth muscle actin (α-SMA), collagen 1A1 (COL1A1), and TGF beta receptor 2 (TGFBR2) protein levels in LX-2 cells were analyzed using immunocytochemistry and western blotting.

Results

Hsa_circ_0009096 exhibited more resistance to RNase R and actinomycinD digestion than UTRN mRNA. Hsa_circ_0009096 expression increased significantly in LX-2 cells treated with TGF-β1, accompanied by elevated α-SMA and COL1A1 expression. Hsa_circ_0009096 siRNAs effectively promoted miR-370-3p and suppressed TGFBR2 expression in LX-2 cells, mediated by direct association of hsa_circ_0009096 with miR-370-3p. Hsa_circ_0009096 siRNA interfered with the cell cycle progression, promoted apoptosis, and reduced α-SMA and COL1A1 expression in LX-2 cells treated with TGF-β1. MiR-370-3p inhibitors mitigated the alterations in cell cycle progression, apoptosis, and α-SMA, COL1A1, and TGFBR2 expression in LX-2 cells caused by hsa_circ_0009096 siRNA. In conclusion, hsa_circ_0009096 promoted HSC proliferation and hepatic fibrosis during BA pathogenesis by accelerating TGFBR2 expression by sponging miR-370-3p.

Biliatresone induces cholangiopathy in C57BL/6J neonates

Exposure to plant toxins or microbiota that are able to digest common food ingredients to toxic structures might be responsible for biliary atresia (BA). An isoflavonoid, biliatresone is known to effectively alter the extrahepatic bile duct (EHBD) development in BALB/c mice. Biliatresone causes a reduction of Glutathione (GSH) levels, SOX17 downregulation and is effectively countered with N-Acetyl-L-cysteine treatment in vitro. Therefore, reversing GSH-loss appears to be a promising treatment target for a translational approach. Since BALB/c mice have been described as sensitive in various models, we evaluated the toxic effect of biliatresone in robust C57BL/6J mice and confirmed its toxicity. Comparison between BALB/c and C57BL/6J mice revealed similarity in the toxic model. Affected neonates exhibited clinical symptoms of BA, such as jaundice, ascites, clay-colored stools, yellow urine and impaired weight gain. The gallbladders of jaundiced neonates were hydropic and EHBD were twisted and enlarged. Serum and histological analysis proved cholestasis. No anomalies were seen in the liver and EHBD of control animals. With our study we join a chain of evidence confirming that biliatresone is an effective agent for cross-lineage targeted alteration of the EHBD system.

Intraoperative hepatic subcapsular spider-like telangiectasia sign for the definitive diagnosis of biliary atresia

OBJECTIVE

To evaluate the accuracy of intraoperative hepatic subcapsular spider-like telangiectasia (HSST) sign for differentiating biliary atresia (BA) from other causes of hepatic cholestasis.

METHODS

The data of 69 patients with jaundice treated from January 2019 to December 2021 were retrospectively analyzed. Based on intraoperative cholangiography (IOC), the patients were divided into two groups: the BA group (n = 49) and the non-BA group (n = 20). The biochemistry tests, liver ultrasound, liver stiffness value and HSST sign of the two groups were compared.

RESULTS

The incidence of abnormal gallbladder, elevated γ-glutamyl transpeptidase (γ-GGT) > 182.0U/L and abnormal liver stiffness (> 6.4 kPa) in BA group were significantly higher than those in non-BA group (P < 0.001). The HSST sign was present in all BA patients and not found in non-BA group. The area under receiver operating curve of direct bilirubin(DBIL), γ-GGT, abnormal gallbladder, liver stiffness value and HSST sign were 0.53, 0.84, 0.78, 0.96, and 1.00, respectively. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value(NPV) of HSST sign in the diagnosis of BA were all 100%.

CONCLUSION

Presence of HSST sign on diagnostic laparoscopy is highly suggestive of BA.It can be used in the differential diagnosis of BA and non-BA.

LEVEL OF EVIDENCE

Level III.

TWEAK/FN14 promotes profibrogenic pathway activation in Prominin-1-expressing hepatic progenitor cells in biliary atresia

BACKGROUND AND AIMS

Biliary atresia (BA), a congenital cholestatic liver disease, commonly culminates in end-stage liver disease. We previously demonstrated in BA that Prominin-1 ( Prom1 )-expressing hepatic progenitor cells (HPCs) expand within regions of developing fibrosis, giving rise to cholangiocytes within biliary ductular reactions. Null mutation of Prom1 or ablation of cells expressing Prom1 significantly diminishes fibrogenesis. FN14, the receptor for TNF-like weak inducer of apoptosis (TWEAK), is expressed by HPCs. TWEAK/FN14 signaling promotes fibrosis in multiple organ systems. Therefore, we hypothesized that TWEAK/FN14 signaling mediates Prom1 -expressing HPC proliferation leading to profibrogenic ductular reactions in BA.

APPROACH AND RESULTS

The experimental mouse model of BA mediated by perinatal rhesus rotavirus (RRV) infection resulted in increased co-expression of Fn14 in Prom1 -expressing HPCs within regions of ductular reactions. FN14 antagonist L524-0366 decreased ductular reactions, biliary fibrosis and periportal fibroblast activation in RRV injury. L524-0366 inhibition also demonstrated loss of downstream noncanonical NF-kB signaling expression in RRV injury. Murine HPC organoids demonstrated accelerated organoid growth and proliferation when treated with recombinant TWEAK. Increased organoid proliferation with recombinant TWEAK was lost when also treated with L524-0366. Analysis of a large publicly available RNA sequencing database of BA and normal control patients revealed significant increases in expression of PROM1 , FN14 , and genes downstream of TNF signaling and noncanonical NF-κB signaling pathways in BA infants. Infants who failed to achieve bile drainage after hepatoportoenterostomy had higher relative levels of FN14 expression.

CONCLUSION

TWEAK/FN14 signaling activation in Prom1 -expressing HPCs contributes to proliferation of profibrogenic ductular reactions in BA.

Neonatal Hepatic Myeloid Progenitors Expand and Propagate Liver Injury in Mice

BACKGROUND

Biliary atresia (BA) is a progressive pediatric inflammatory disease of the liver that leads to cirrhosis and necessitates liver transplantation. The rapid progression from liver injury to liver failure in children with BA suggests that factors specific to the perinatal hepatic environment are important for disease propagation. Hematopoietic stem and progenitor cells (HSPCs) reside in the fetal liver and are known to serve as central hubs of inflammation. We hypothesized that HSPCs are critical for the propagation of perinatal liver injury (PLI).

METHODS

Newborn BALB/c mice were injected with rhesus rotavirus (RRV) to induce PLI or with PBS as control. Livers were compared using histology and flow cytometry. To determine the effects of HSPCs on PLI, RRV-infected neonatal mice were administered anti-CD47 and anti-CD117 to deplete HSPCs.

RESULTS

PLI significantly increased the number of common myeloid progenitors and the number of CD34⁺ hematopoietic progenitors. Elimination of HSPCs through antibody-mediated myeloablation rescued animals from PLI and significantly increased survival (RRV+isotype control 36.4% vs. RRV+myeloablation 77.8%, Chi-test = 0.003).

CONCLUSIONS

HSPCs expand as a result of RRV infection and propagate PLI. Targeting of HSPCs may be useful in preventing and treating neonatal inflammatory diseases of the liver such as BA.

Serum matrix metalloproteinase-7 levels in infants with cholestasis and biliary atresia

Background

The aim of this study was to evaluate the serum level of matrix metalloproteinase 7 (MMP7) in infants with cholestasis and the diagnostic values of this biomarker to differentiate biliary atresia (BA) from other causes of cholestasis.

Methods

This multi-center study is conducted during 2 years in Mofid children’s hospital and Children’s Medical Center, Pediatrics Center of Excellence Tehran, Iran. 54 infants with cholestasis were enrolled in this study with a control group consists of 41 healthy infants with the same age. Serum samples were taken from all these patients to assess serum levels of MMP7, Gamma-glutamyl Transferase (GGT). For each biomarker, we calculated the sensitivity and specificity and other statistical characteristics.

Results

There were 89 subjects, 22 patients with BA, 32 patients with non-BA cholestasis and 41 subjects as control group. The mean serum MMP7 levels in BA, non-BA cholestasis and control group was 15.91 ng/ml ± 6.64, 4.73 ng/ml ± 2.59 and 0.49 ng/ml ± 0.33, respectively. The best cut-off point is calculated 7.8 ng/ml for MMP7 and 434.5 U/L for GGT. The area under curve (AUC) for these two markers are 0.988 ± 0.008 and 0.854 ± 0.052, respectively. The sensitivity and specificity of MMP7 to differentiate biliary atresia from nonbiliary atresia cholestasis in our study was 95.5% and 94.5%, respectively. The sensitivity and specificity of GGT was 77.3% and 77.8%, respectively. These results show that the MMP7 has more sensitivity and specificity in differentiation.

Conclusion

MMP7 demonstrated good accuracy to differentiate biliary atresia from other causes of cholestasis.

Body composition correlates with laboratory parameters and disease severity in infants with biliary atresia

AIM

Infants with biliary atresia (BA) generally have chronic malnutrition. However, the best anthropometric measure to assess malnutrition and its correlation with disease severity is unknown. We aimed to assess correlations of various anthropometric measurements, including air displacement plethysmography (ADP), with laboratory parameters and with the pediatric end-stage liver disease (PELD) score in infants with BA.

METHODS

Infants with BA were followed at a pediatric liver transplantation center during 2014-2018. Follow-up comprised laboratory tests and nutritional assessment by a dietitian including dietary intake, weight, height, mid-upper arm circumference (MUAC), and skin-fold thickness. Fat-free mass (FFM) and fat mass (FM) were measured by ADP.

RESULTS

Forty-three nutritional evaluations were performed in 28 infants with BA (13 boys, 44.4%). The median age was 20.7 weeks (IQR: 13-25.9). Based on the various anthropometry modalities, infants with BA were found to be malnourished on most of the visits; 63% had a MUAC-Z score lower than -2 standard deviations. High serum bilirubin level predicted lower weight for age, length for age, and MUAC-Z. Lower MUAC-Z was associated with a higher PELD score. Neither FM mass nor FFM correlated with PELD or with serum bilirubin level. However, FM correlated with skin-fold thickness-Z and was low in most patients.

CONCLUSIONS

The majority of BA infants suffer from malnutrition as assessed by most anthropometrics modalities; low MUAC correlated best with disease severity and serum bilirubin level. Further studies are warranted to determine the contribution of FM measurement by ADP to the anthropometric assessment of infants with BA.

Update on Etiology and Pathogenesis of Biliary Atresia

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

Development of the Patient- and Observer-Reported PRUCISION Instruments to Assess Pruritus and Sleep Disturbance in Pediatric Patients with Cholestatic Liver Diseases

INTRODUCTION

Understanding how patients experience their disease is a vital step in optimal disease management, and patient- and observer-reported outcome (PRO and ObsRO, respectively) measures can add important details to clinical information that is obtained as novel treatments are developed. Instruments that measure meaningful symptoms and impacts from the perspective of pediatric patients with cholestatic liver disease or their caregivers are needed. This study aimed to identify salient concepts in pediatric cholestatic liver disease, develop novel PRO and ObsRO instruments, and establish the instruments' content validity.

METHODS

Relevant signs, symptoms, and impacts of cholestatic liver disease were identified through a literature review, interviews with expert clinicians, and concept elicitation interviews with children and caregivers of children who had progressive familial intrahepatic cholestasis (PFIC), Alagille syndrome, biliary atresia, or primary sclerosing cholangitis. Additional cognitive debriefing interviews with patients and caregivers were performed to ensure that participants could understand the instructions, questions, and response scales of the PRO and ObsRO instruments, with modifications made as necessary to improve comprehension and/or usability.

RESULTS

A total of 36 interviews with patients and caregivers were conducted. Pruritus and sleep disturbance (e.g., difficulty falling or staying asleep due to itch) were identified as the most problematic symptom and significant impact, respectively, of the pediatric cholestatic liver diseases assessed. The ObsRO and PRO instruments, called PRUCISION, focus on these key disease features in the morning and evening. Several modifications were made to the draft instruments following cognitive interviews. The final PRUCISION PRO and ObsRO measures are designed as an electronic diary to be completed twice daily. The response scales include pictorial, verbal, and numeric scales.

CONCLUSION

Novel PRO and ObsRO PRUCISION instruments were created that evaluate the patient experience of cholestatic pruritus in children with PFIC and other cholestatic liver diseases. The content validity of the PRUCISION instruments is established.

Comparative analysis of cystic biliary atresia and choledochal cysts

OBJECTIVE

Cystic biliary atresia (CBA) is a rare and peculiar type of biliary atresia (BA) that is easily confused with infantile choledochal cysts (CCs). This study explored information for early CBA diagnosis and treatment.

METHOD

The authors retrospectively analyzed the clinical data of 32 children with hilar cysts from January 2013 to May 2021. According to the diagnosis, they were divided into the CBA (n = 12) and CC (n = 20) groups. Patient features, biochemical indexes, preoperative ultrasound characteristics, cholangiography features, and intraoperative findings were analyzed and compared between the two groups.

RESULTS

The alanine aminotransferase, aspartate aminotransferase, total bilirubin, and direct bilirubin levels in the CBA group were higher than in the CCs group (P < 0.05). Additionally, B-mode ultrasound showed a cystic mass in front of the hepatic hilum, and the cyst size was much smaller in the CBA group compared with the CC group (2.2 ± 1.3 cm vs. 6.0 ± 2.2 cm, P < 0.001). Among all of the parameters, cyst width was the most accurate for identifying CBA and CCs. A cutoff value of 2.5 cm (area under the curve, 0.98, P < 0.001) showed 90.9% sensitivity and 95% specificity for cyst size.

CONCLUSION

For children with early-onset severe jaundice, and if the width of the cystic mass was ≤2.5 cm, a diagnosis of CBA was highly likely. Early cholangiography and surgical treatment are necessary for the effective treatment of these infants.

Latest diagnostic performance of different ultrasonic features for biliary atresia

BACKGROUND

Early diagnosis of biliary atresia (BA) is an important clinical challenge.

PURPOSE

To summarize the latest diagnostic performance of different ultrasonic (US) features for BA.

MATERIAL AND METHODS

MeSH terms "biliary atresia" and "ultrasonography" and related hyponyms were used to search PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials. Eligible articles were included and data were retrieved. The methodologic quality was assessed by version 2 of the Quality Assessment of Diagnostic Accuracy Studies tool. Estimated sensitivity and specificity of each US feature were calculated by Stata 14.0.

RESULTS

Fifty eligible studies on 5622 patients were included. Respective summary sensitivity and specificity were 77% (95% CI=69-84) and 98% (95% CI=96-99) for triangular cord sign (TCS) in 32 studies, 86% (95% CI=78-92) and 86% (95% CI=72-94) for shear wave elastography (SWE) in seven studies, 75% (95% CI=65-83) and 92% (95% CI=86-95) for gallbladder and biliary system abnormality (GBA) in 25 studies, and 81% (95% CI=69-90) and 79% (95% CI=67-87) for hepatic artery (HA) enlargement in seven studies. The overall US features from 11 studies yielded a summary sensitivity of 84% (95% CI=72-92) and specificity of 86% (95% CI=77-92).

CONCLUSION

TCS and GBA were the two most widely accepted US features currently used for differential diagnosis of BA. The newly developed SWE was an objective and convenient method with good diagnostic performance. HA enlargement can be used as an auxiliary sign.

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.

Human amniotic fluid stem cells attenuate cholangiocyte apoptosis in a bile duct injury model of liver ductal organoids

PURPOSE

Biliary atresia (BA) is a fibro-obliterative cholangiopathy that involves both extrahepatic and intrahepatic bile ducts in infants. Cholangiocyte apoptosis has an influence on the fibrogenesis process of bile ducts and the progression of liver fibrosis in BA. Human amniotic fluid stem cells (hAFSCs) are multipotent cells that have ability to inhibit cell apoptosis. We aimed to investigate whether hAFSCs have the potential to attenuate cholangiocyte apoptosis and injury induced fibrogenic response in our ex vivo bile duct injury model of liver ductal organoids.

METHODS

The anti-apoptotic effect of hAFSCs was tested in the acetaminophen-induced injury model of neonatal mouse liver ductal organoids (AUP #42681) by using direct and indirect co-culture systems. Cell apoptosis and proliferation were evaluated by immunofluorescent staining. Expression of fibrogenic cytokines was analyzed by RT-qPCR. Data were compared using one-way ANOVA with post hoc test.

RESULTS

In our injury model, liver ductal organoids that were treated with hAFSCs in both direct and indirect co-culture systems had a significantly smaller number of apoptotic cholangiocytes and decreased expression of fibrogenic cytokines, transforming growth factor beta-1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB). Moreover, hAFSCs increased cholangiocyte proliferation in injured organoids.

CONCLUSION

hAFSCs have the ability to protect the organoids from injury by decreasing cholangiocyte apoptosis and promoting cholangiocyte proliferation. This protective ability of hAFSCs leads to inhibition of the fibrogenic response in the injured organoids. hAFSCs have high therapeutic potential to attenuate liver fibrogenesis in cholangiopathic diseases such as BA.

Biological and Histological Assessment of the Hepatoportoenterostomy Role in Biliary Atresia as a Stand-Alone Procedure or as a Bridge toward Liver Transplantation

Background and objectives: In patients with biliary atresia (BA), hepatoportoenterostomy (HPE) is still a valuable therapeutic tool for prolonged survival or a safer transition to liver transplantation. The main focus today is towards efficient screening programs, a faster diagnostic, and prompt treatment. However, the limited information on BA pathophysiology makes valuable any experience in disease management. This study aimed to analyze the evolution and survival of patients with BA referred for HPE (Kasai operation) in our department. Materials and Methods: A retrospective analysis was performed on fourteen patients with BA, diagnosed in the pediatric department and further referred for HPE in our surgical department between 2010 and 2016. After HPE, the need for transplantation was assessed according to patients cytomegalovirus (CMV) status, and histological and biochemical analysis. Follow-up results at 1-4 years and long term survival were assessed. Results: Mean age at surgery was 70 days. Surgery in patients younger than 60 days was correlated with survival. Jaundice's clearance rate at three months was 36%. Total and direct bilirubin values had a significant variation between patients with liver transplants and native liver (p = 0.02). CMV was positive in eight patients, half with transplant need and half with native liver survival. Smooth muscle actin (SMA) positivity was proof of advanced fibrosis. The overall survival rate was 79%, with 75% for native liver patients and an 83% survival rate for those with liver transplantation. Transplantation was performed in six patients (43%), with a mean of 10 months between HPE and transplantation. Transplanted patients had better survival. Complications were diagnosed in 63% of patients. The mean follow-up period was six years. Conclusions: HPE, even performed in advanced cirrhosis, allows a significant survival, and ensures an essential time gain for patients requiring liver transplantation. A younger age at surgery is correlated with a better outcome, despite early CMV infection.

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.

Ileal bile acid transporter inhibition as an anticholestatic therapeutic target in biliary atresia and other cholestatic disorders

Biliary atresia is a rare cholestatic liver disease that presents in infants and rapidly advances to death in the absence of intervention. As a result of blockage or destruction of the biliary tract, bile acids accumulate and drive inflammation, fibrosis, and disease progression. The standard of care, Kasai portoenterostomy (KPE), is typically performed shortly after diagnosis (currently at ~ 2 months of age) and aims to restore bile flow and relieve cholestasis. Nevertheless, most patients continue to experience liver injury from accumulation of bile acids after KPE, since there are no known effective therapeutics that may enhance survival after KPE. Improving cholestasis via interruption of the enterohepatic circulation of bile acids may directly attenuate hepatic bile acid retention and reduce the risk of early organ failure. Directly addressing intrahepatic accretion of bile acids to avoid inherent bile acid toxicities provides an attractive and plausible therapeutic target for biliary atresia. This review explores the novel therapeutic concept of inhibiting the sole ileal bile acid transporter (IBAT), also known as ASBT (apical sodium-bile acid transporter, encoded by SLC10A2), as a means to reduce hepatic bile acid concentration after KPE. By reducing return of bile acids to the cholestatic liver, IBAT inhibitors may potentially lessen or delay liver damage associated with the hepatotoxicity and cholangiopathy of bile acid accumulation. The clinical programs of 2 IBAT inhibitors in development for the treatment of pediatric cholestatic liver diseases, maralixibat and odevixibat, are highlighted.

Hypervolemic hyponatremia and transplant-free survival in children with cirrhosis due to biliary atresia

BACKGROUND

Biliary atresia is the number one cause of cirrhosis and liver transplantation in children. Hyponatremia is the most important electrolytic disturbance observed in decompensated cirrhosis. Studies of hyponatremia in cirrhotic children are scarce and those that exist have defined hyponatremia as serum sodium < 130 mEq/L lasting for at least 7 days.

METHODS

We evaluated transplant-free survival (Kaplan-Meier) of children with cirrhosis due to biliary atresia and serum sodium < 130 mEq/L persisting for 1, 2-6, and ≥7 days. This was a single-center, historical cohort that included all patients aged ≤ 18 years on a liver transplantation waiting list.

RESULTS

We studied 128 patients. The overall frequency of hyponatremia was 30.5% (39/128). Thirteen patients (10.2%) had hyponatremia when put on the list, and 20.3% developed it during follow-up. The Kaplan-Meier overall transplant-free survival rate was 83.3%. Patients with persistent hyponatremia for at least two days had the lowest transplant-free survival. Glomerular filtration rate (P = .00, RR = 0.96, IC 95% = 0.94-0.99), BMI/age Z-score (P = .02, RR = 0.59, IC 95% = 0.39-0.91), INR (P = .00, RR = 1.43, IC 95% = 1.17-1.74), and serum sodium (P = .04, RR = 0.91, IC 95% = 0.84-0.99) were independently associated with transplant-free survival. We did not observe any difference in mortality prediction after adding sodium to the original PELD score.

CONCLUSIONS

We conclude that persistent hyponatremia lasting at least two days may herald poor prognosis for children with cirrhosis due to biliary atresia.

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

Biliary atresia (BA) is the most common reason for pediatric liver transplant. BA's varied presentation, natural history, and treatment with the Kasai portoenterostomy have been well described; however, when BA starts relative to birth has not been clearly defined. In this review, we discuss laboratory, imaging, and clinical data which suggest that most if not all forms of BA may start before birth. This early onset has implications in terms of delivering treatments earlier and identifying possible factors underlying BA's etiology.

Biliary atresia combined with progressive familial intrahepatic cholestasis type 3: A case report and review of the literature

RATIONALE

Neonatal cholestasis is one of the most serious diseases in infancy. Progressive familial intrahepatic cholestasis (PFIC) is a disease that leads to intrahepatic cholestasis. It is one of the common causes of neonatal cholestasis in addition to biliary atresia (BA). The differential diagnosis of neonatal cholestasis is clinically challenging for pediatricians.

PATIENT CONCERNS

A 4-month-old female presented with severe jaundice, pruritus, and pale stool for 20 days. Abnormally strong echoes near the portal area, an abnormally small gallbladder with an irregularly stiff wall, and splenomegaly were identified on abdominal ultrasound. Blood tests showed elevated alanine aminotransferase, total bilirubin, conjugated bilirubin, gamma-glutamyltranspeptidase, and total bile acid levels.

DIAGNOSIS

Intraoperative cholangiography showed BA. ABCB4 gene mutation IVS13+6G>A/G was confirmed by genetic testing. The patient was diagnosed with BA combined with PFIC3.

INTERVENTIONS

Kasai portoenterostomy and ursodeoxycholic acid were used for treatment.

OUTCOMES

Her clinical symptoms and blood tests improved gradually. No recurrence was noted during 1 year of follow-up.

LESSONS

Additional examinations, such as genetic testing, should be considered in patients with BA who had refractory jaundice after Kasai portoenterostomy in order to exclude intrahepatic cholestasis.