Pathogenesis of biliary atresia: defining biology to understand clinical phenotypes

Pediatric cirrhotic cardiomyopathy: literature review and effect size estimations of selected parameters

Liver cirrhosis is a significant global health concern, and cirrhotic cardiomyopathy (CCM) is a notable complication affecting both adults and children. While CCM is well-studied in adults, understanding its manifestation and diagnostic criteria in pediatric patients remains a challenge. This review explores the evidence for structural and functional cardiac alterations in children with liver cirrhosis. Structural abnormalities, including increased left ventricular mass index (LVMI) and altered left ventricular wall thickness ratios, are prevalent in pediatric CCM. These abnormalities persist even after liver transplantation, highlighting the systemic impact of liver disease. Evidence suggests that altered systolic and diastolic function, as well as electrocardiographic abnormalities such as prolonged QT intervals, are common in pediatric CCM. Blood biomarkers, including brain natriuretic peptide (BNP) and troponin levels, offer insights into cardiac function in pediatric cirrhotic patients. Elevated BNP levels correlate with adverse outcomes, indicating its potential as a prognostic marker. However, further research is needed to elucidate the diagnostic utility of these biomarkers in pediatric CCM.

CONCLUSION

This review provides estimates of the standardized mean difference among selected cardiac parameters in children with and without cirrhosis. Tailored diagnostic criteria and comprehensive assessment methods will be essential for accurate diagnosis and effective management of pediatric CCM.

WHAT IS KNOWN

• CCM adds to the burden of care of patients with cirrhosis. • Diagnostic criteria for adults are evolving, but there are no specific criteria for pediatric CCM.

WHAT IS NEW

• Cardiac function in children with cirrhosis indicates some parameters not considered in adults are altered. • Effect size estimations for certain parameters provide a guideline for future research into pediatric CCM.

Perinatal liver inflammation is associated with persistent elevation of CXCL10 and its canonical receptor CXCR3 on common myeloid progenitors

Biliary atresia (BA) is a leading cause of liver failure in infants. Despite effective surgical drainage, patients with BA exhibit attenuated immune responses to childhood vaccines, suggesting there are long-lasting alterations to immune function. The perinatal liver is home to hematopoietic stem and progenitor cells (HSPCs) and serves as the epicenter for rapidly progressive and significantly morbid inflammatory diseases like BA. We have previously established the role of neonatal myeloid progenitors in the pathogenesis of perinatal liver inflammation (PLI) and hypothesize that PLI leads to long-term changes to HSPCs in mice that recovered from PLI. To test this hypothesis, we compared the changes that occur to HSPCs and mature myeloid populations in the bone marrow of adult mice during homeostasis and during PLI. Our results demonstrate that HSPCs from animals that recover from PLI ("PLI-recovered") undergo long-term expansion with a reduced proliferative capacity. Notably, PLI leads to persistent activation of common myeloid progenitors through the involvement of CXCL10 and its canonical receptor, CXCR3. Our data suggests that the CXCR3-CXCL10 axis may mediate the changes in HSPCs that lead to altered immune function observed in BA, providing support for a targetable pathway to mitigate the detrimental long-term immune effects observed in patients with BA.

Specific binding sites on Rhesus rotavirus capsid protein dictate the method of endocytosis inducing the murine model of biliary atresia

Biliary atresia (BA) is the leading indication for pediatric liver transplantation. Rhesus rotavirus (RRV)-induced murine BA develops an obstructive cholangiopathy that mirrors the human disease. We have previously demonstrated the "SRL" motif on RRV's VP4 protein binds to heat shock cognate 70 protein (Hsc70) facilitating entry into cholangiocytes. In this study, we analyzed how binding to Hsc70 affects viral endocytosis, intracellular trafficking, and uniquely activates the signaling pathway that induces murine BA. Inhibition of clathrin- and dynamin-mediated endocytosis in cholangiocytes following infection demonstrated that blocking dynamin decreased the infectivity of RRV, whereas clathrin inhibition had no effect. Blocking early endosome trafficking resulted in decreased viral titers of RRV, whereas late endosome inhibition had no effect. After infection, TLR3 expression and p-NF-κB levels increased in cholangiocytes, leading to increased release of CXCL9 and CXCL10. Infected mice knocked out for TLR3 had decreased levels of CXCL9 and CXCL10, resulting in reduced NK cell numbers. Human patients with BA experienced an increase in CXCL10 levels, suggesting this as a possible pathway leading to biliary obstruction. Viruses that use Hsc70 for cell entry exploit a clathrin-independent pathway and traffic to the early recycling endosome uniquely activating NF-κB through TLR3, leading to the release of CXCL9 and CXCL10 and inducing NK cell recruitment. These results define how the "SRL" peptide found on RRV's VP4 protein modulates viral trafficking, inducing the host response leading to bile duct obstruction.NEW & NOTEWORTHY In this study, we have determined that the presence of the "SRL" peptide on RRV alters its method of endocytosis and intracellular trafficking through viral binding to heat shock cognate 70 protein. This initiates an inflammatory pathway that stimulates the release of cytokines associated with biliary damage and obstruction.

Stable two- and three-dimensional cholangiocyte culture systems from extrahepatic bile ducts of biliary atresia patients: use of structural and functional bile duct epithelium models for in vitro analyses

We herein report two- (2D) and three-dimensional (3D) culture methods of cholangiocytes originating from extrahepatic bile ducts of biliary atresia (BA) patients. Cells were stabilized for in vitro analyses, and 3D culture by two different methods showed the structural and functional features of cholangiocytes in the gel scaffold. First, cells were obtained from gallbladder contents or resected tissues of patients at surgery and then cultured in our original conditioned medium with a cocktail of signaling inhibitors that maintains the immaturity and amplification of cells. Cells were immortalized by inducing SV40T and hTERT genes using lentivirus systems. Immunostaining with CK19 and Sox9 antibodies confirmed the cells as cholangiocytes. 3D organoids were formed in Matrigel in two different ways: by forming spheroids or via vertical growth from 2D cell sheets (2 + 1D culture). Organoids generated with both methods showed the uptake and excretion of rhodamine-123, and duct-like structures were also found. Our culture methods are simpler than previously reported methods and still show the structural and functional characteristics of cholangiocytes. Thus, this system is expected to be useful for the in vitro investigation of cholangiocyte damage or regeneration in BA patients.

Kasai Portoenterostomy, Successful Liver Transplantation, and Immunosuppressive Therapy for Biliary Atresia in a Female Baby: A Case Report

Background

Biliary atresia (BA) is a severe neonatal progressive cholangiopathy of unknown etiology. A timely Kasai portoenterostomy (KPE) improves survival of the native liver in patients with BA, although liver transplantation remains the ultimate treatment for most (60%-80%) patients. However, postoperative adverse effects of liver transplantation may be significant. In addition, patients require lifelong immunosuppressive therapy after liver transplantation.

Case Summary

Here, we report a case of a newborn female baby (birthday: 10-03-2018) with congenital BA (confirmed at 76 days of life) who survived KPE (first surgery at 85 days of life) and underwent successful living-related liver transplantation (LRLT) (second surgery at 194 days of life). Additionally, we reviewed the existing literature on BA. After KPE (at 85 days of life), the liver function of the baby did not improve, and the indicators of liver and kidney function showed a trend of aggravation, indicating that the liver function had been seriously damaged before KPE (at 85 days of life), demonstrating the urgent need for liver transplantation surgery. The female baby survived after part of her father's liver was successfully transplanted into her body (at 194 days of life). The patient recovered successfully. No other diseases were found at the 4-year follow-up, and all indices of liver and kidney functions tended to be normal.

Conclusion

This case highlights the following. Postoperative alkaline phosphatase was consistently above the normal range, although the reason for this was unclear; neither tacrolimus nor cyclosporine A has formulations designed specifically for infants, which does not meet the needs of clinical individualized medication, suggesting that these anti-rejection drugs are future development directions. Only one case of congenital BA has been found thus far in Hefei, and this case has extremely important reference significance for the prevention, treatment, and diagnosis of BA in Hefei, Anhui province.

LncRNA MEG9 Promotes Inflammation and Liver Fibrosis Through S100A9 in Biliary Atresia

BACKGROUND

The pathogenesis of biliary atresia (BA) remains elusive. We aimed to investigate the role of long noncoding RNA (lncRNA) MEG9 in BA.

METHODS

LncRNA microarray was conducted to identify differentially expressed lncRNAs in three BA and three para-hepatoblastoma liver tissues. RT-qPCR validated the results. Human intrahepatic bile duct epithelial cells (HIBECs) were stably transfected with lncRNA MEG9 knockdown/overexpression to investigate its cellular localization and function. RNA sequencing (RNA-seq), differentially expressed genes (DEGs) analysis and gene set enrichment analysis were applied to MEG9-overexpresed HIBECs. RNA pull-down and mass spectrometry explored the interacting protein of MEG9, while clinical information was reviewed.

RESULTS

436 differentially expressed lncRNAs were identified, with MEG9 highly upregulated in BA. RT-qPCR further confirmed MEG9's overexpression in BA and diagnostic potential (AUC = 0.9691). MEG9 was predominantly located in the nucleus and significantly promoted cell proliferation and migration. RNA-seq revealed inflammation- and extracellular matrix-related pathways enriched in MEG9-overexpressing HIBECs, with upregulated cytokine genes like CXCL6 and IL6. MMP-7 and collagen I were also overexpressed. Furthermore, 38 proteins were identified to specifically interact with MEG9, and S100A9 was highly expressed in cell models. S100A9 was also significantly upregulated in BA liver tissue and correlated with MEG9 expression (r = 0.313, p < 0.05), albumin level (r = -0.349, p < 0.05), and platelet level (r = -0.324, p < 0.05).

CONCLUSION

MEG9 influences cholangiocyte proliferation, migration, and cytokine production, potentially regulating BA inflammation and fibrosis via S100A9 interaction.

Diagnostic accuracy of serum matrix metalloproteinase-7 as a biomarker of biliary atresia in a large North American cohort

BACKGROUND AND AIMS

High levels of serum matrix metalloproteinase-7 (MMP-7) have been linked to biliary atresia (BA), with wide variation in concentration cutoffs. We investigated the accuracy of serum MMP-7 as a diagnostic biomarker in a large North American cohort.

APPROACH AND RESULTS

MMP-7 was measured in serum samples of 399 infants with cholestasis in the Prospective Database of Infants with Cholestasis study of the Childhood Liver Disease Research Network, 201 infants with BA and 198 with non-BA cholestasis (age median: 64 and 59 days, p = 0.94). MMP-7 was assayed on antibody-bead fluorescence (single-plex) and time resolved fluorescence energy transfer assays. The discriminative performance of MMP-7 was compared with other clinical markers. On the single-plex assay, MMP-7 generated an AUROC of 0.90 (CI: 0.87-0.94). At cutoff 52.8 ng/mL, it produced sensitivity = 94.03%, specificity = 77.78%, positive predictive value = 64.46%, and negative predictive value = 96.82% for BA. AUROC for gamma-glutamyl transferase = 0.81 (CI: 0.77-0.86), stool color = 0.68 (CI: 0.63-0.73), and pathology = 0.84 (CI: 0.76-0.91). Logistic regression models of MMP-7 with other clinical variables individually or combined showed an increase for MMP-7+gamma-glutamyl transferase AUROC to 0.91 (CI: 0.88-0.95). Serum concentrations produced by time resolved fluorescence energy transfer differed from single-plex, with an optimal cutoff of 18.2 ng/mL. Results were consistent within each assay technology and generated similar AUROCs.

CONCLUSIONS

Serum MMP-7 has high discriminative properties to differentiate BA from other forms of neonatal cholestasis. MMP-7 cutoff values vary according to assay technology. Using MMP-7 in the evaluation of infants with cholestasis may simplify diagnostic algorithms and shorten the time to hepatoportoenterostomy.

A Pilot Study for Biliary Atresia Diagnosis: Fluorescent Imaging of Indocyanine Green in Stool

BACKGROUND

Biliary atresia is the most common cause of obstructive jaundice in infants and conventional cholangiography is the current diagnostic gold standard. Fluorescent cholangiography with indocyanine green can enhance biliary tree visualization during surgery because it is exclusively excreted into the bile ducts and eventually into the intestine. Therefore, we hypothesized that indocyanine green presence in stool could confirm bile duct patency in infants.

METHODS

A prospective single center cohort study was performed on infants (age ≤ 12 months) with and without jaundice after obtaining IRB approval. Indocyanine green was administered intravenously (0.1 mg/kg). Soiled diapers collected post-injection were imaged for fluorescence.

RESULTS

After indocyanine green administration, fluorescence was detected in soiled diapers for control patients (n = 4, x = 14 h22 m post-injection) and jaundiced patients without biliary atresia (n = 11, x = 13 h28 m post-injection). For biliary atresia patients (n = 7), post-injection soiled diapers before and after Kasai portoenterostomy were collected. Fluorescence was not detected in stool from 6 of 7 biliary atresia patients. As a test, indocyanine green detection in stool was 97% accurate for assessing biliary patency.

CONCLUSION

Fluorescent Imaging for Indocyanine Green (FIInd Green) in stool is a fast and accurate approach to assess biliary patency non-invasively in infants.

LEVEL OF EVIDENCE

Level III.

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.

Identification of diagnostic biomarkers and potential therapeutic targets for biliary atresia via WGCNA and machine learning methods

Biliary atresia (BA) is a severe and progressive biliary obstructive disease in infants that requires early diagnosis and new therapeutic targets. This study employed bioinformatics methods to identify diagnostic biomarkers and potential therapeutic targets for BA. Our analysis of mRNA expression from Gene Expression Omnibus datasets revealed 3,273 differentially expressed genes between patients with BA and those without BA (nBA). Weighted gene coexpression network analysis determined that the turquoise gene coexpression module, consisting of 298 genes, is predominantly associated with BA. The machine learning method then filtered out the top 2 important genes, CXCL8 and TMSB10, from the turquoise module. The area under receiver operating characteristic curves for TMSB10 and CXCL8 were 0.961 and 0.927 in the training group and 0.819 and 0.791 in the testing group, which indicated a high diagnostic value. Besides, combining TMSB10 and CXCL8, a nomogram with better diagnostic performance was built for clinical translation. Several studies have highlighted the potential of CXCL8 as a therapeutic target for BA, while TMSB10 has been shown to regulate cell polarity, which was related to BA progression. Our analysis with qRT PCR and immunohistochemistry also confirmed the upregulation of TMSB10 at mRNA and protein levels in BA liver samples. These findings highlight the sensitivity of CXCL8 and TMSB10 as diagnostic biomarkers and their potential as therapeutic targets for BA.

Impact of gallbladder hypoplasia on hilar hepatic ducts in biliary atresia

BACKGROUND

Biliary atresia (BA) is an intractable disease of unknown cause that develops in the neonatal period. It causes jaundice and liver damage due to the destruction of extrahepatic biliary tracts,. We have found that heterozygous knockout mice of the SRY related HMG-box 17 (Sox17) gene, a master regulator of stem/progenitor cells in the gallbladder wall, exhibit a condition like BA. However, the precise contribution of hypoplastic gallbladder wall to the pathogenesis of hepatobiliary disease in Sox17 heterozygous embryos and human BA remains unclear.

METHODS

We employed cholangiography and histological analyses in the mouse BA model. Furthermore, we conducted a retrospective analysis of human BA.

RESULTS

We show that gallbladder wall hypoplasia causes abnormal multiple connections between the hilar hepatic bile ducts and the gallbladder-cystic duct in Sox17 heterozygous embryos. These multiple hilar extrahepatic ducts fuse with the developing intrahepatic duct walls and pull them out of the liver parenchyma, resulting in abnormal intrahepatic duct network and severe cholestasis. In human BA with gallbladder wall hypoplasia (i.e., abnormally reduced expression of SOX17), we also identify a strong association between reduced gallbladder width (a morphometric parameter indicating gallbladder wall hypoplasia) and severe liver injury at the time of the Kasai surgery, like the Sox17-mutant mouse model.

CONCLUSIONS

Together with the close correlation between gallbladder wall hypoplasia and liver damage in both mouse and human cases, these findings provide an insight into the critical role of SOX17-positive gallbladder walls in establishing functional bile duct networks in the hepatic hilus of neonates.

Proteomics Defines Plasma Biomarkers for the Early Diagnosis of Biliary Atresia

Early diagnosis of biliary atresia (BA) is crucial for improving the chances of survival and preserving the liver function of pediatric patients with BA. Herein, we performed proteomics analysis using data-independent acquisition (DIA) and parallel reaction monitoring (PRM) to explore potential biomarkers for the early diagnosis of BA compared to other non-BA jaundice cases. Consequently, we detected and validated differential protein expression in the plasma of patients with BA compared to the plasma of patients with intrahepatic cholestasis. Bioinformatics analysis revealed the enriched biological processes characteristic of BA by identifying the differential expression of specific proteins. Signaling pathway analysis revealed changes in the expression levels of proteins associated with an alteration in immunoglobulin levels, which is indicative of immune dysfunction in BA. The combination of polymeric immunoglobulin receptor expression and immunoglobulin lambda variable chain (IGL c2225_light_IGLV1-47_IGLJ2), as revealed via machine learning, provided a useful early diagnostic model for BA, with a sensitivity of 0.8, specificity of 1, accuracy of 0.89, and area under the curve value of 0.944. Thus, our study identified a possible effective plasma biomarker for the early diagnosis of BA and could help elucidate the underlying mechanisms of BA.

Mucosal-associated invariant T cells promote ductular reaction through amphiregulin in biliary atresia

BACKGROUND

Biliary atresia (BA) is a neonatal fibro-inflammatory cholangiopathy with ductular reaction as a key pathogenic feature predicting poor survival. Mucosal-associated invariant T (MAIT) cells are enriched in human liver and display multiple roles in liver diseases. We aimed to investigate the function of MAIT cells in BA.

METHODS

First, we analyzed correlations between liver MAIT cell and clinical parameters (survival, alanine transaminase, bilirubin, histological inflammation and fibrosis) in two public cohorts of patients with BA (US and China). Kaplan-Meier survival analysis and spearman correlation analysis were employed for survival data and other clinical parameters, respectively. Next, we obtained liver samples or peripheral blood from BA and control patients for bulk RNA sequencing, flow cytometry analysis, immunostaning and functional experiments of MAIT cells. Finally, we established two in vitro co-culture systems, one is the rhesus rotavirus (RRV) infected co-culture system to model immune dysfunction of human BA which was validated by single cell RNA sequencing and the other is a multicellular system composed of biliary organoids, LX-2 and MAIT cells to evaluate the role of MAIT cells on ductular reaction.

FINDINGS

Liver MAIT cells in BA were positively associated with low survival and ductular reaction. Moreover, liver MAIT cells were activated, exhibited a wound healing signature and highly expressed growth factor Amphiregulin (AREG) in a T cell receptor (TCR)-dependent manner. Antagonism of AREG abrogated the proliferative effect of BA MAIT cells on both cholangiocytes and biliary organoids. A RRV infected co-culture system, recapitulated immune dysfunction of human BA, disclosed that RRV-primed MAIT cells promoted cholangiocyte proliferation via AREG, and further induced inflammation and fibrosis in the multicellular system.

INTERPRETATION

MAIT cells exhibit a wound healing signature depending on TCR signaling and promote ductular reaction via AREG, which is associated with advanced fibrosis and predictive of low survival in BA.

FUNDING

This work was funded by National Natural Science Foundation of China grant (82001589 and 92168108), National Key R&D Program of China (2023YFA1801600) and by Basic and Applied Basic Research Foundation of Guangdong (2020A1515110921).

Farnesoid X receptor agonist tropifexor detoxifies ammonia by regulating the glutamine metabolism and urea cycles in cholestatic livers

Hyperammonemia refers to elevated levels of ammonia in the blood, which is an important pathological feature of liver cirrhosis and hepatic failure. Preclinical studies suggest tropifexor (TXR), a novel non-bile acid agonist of Farnesoid X Receptor (FXR), has shown promising effects on reducing hepatic steatosis, inflammation, and fibrosis. This study evaluates the impact of TXR on hyperammonemia in a piglet model of cholestasis. We here observed blood ammonia significantly elevated in patients with biliary atresia (BA) and was positively correlated with liver injury. Targeted metabolomics and immunblotting showed glutamine metabolism and urea cycles were impaired in BA patients. Next, we observed that TXR potently suppresses bile duct ligation (BDL)-induced injuries in liver and brain with improving the glutamine metabolism and urea cycles. Within the liver, TXR enhances glutamine metabolism and urea cycles by up-regulation of key regulatory enzymes, including glutamine synthetase (GS), carbamoyl-phosphate synthetase 1 (CPS1), argininosuccinate synthetase (ASS1), argininosuccinate lyase (ASL), and arginase 1 (ARG1). In primary mice hepatocytes, TXR detoxified ammonia via increasing ureagenesis. Mechanically, TXR activating FXR to increase express enzymes that regulating ureagenesis and glutamine synthesis through a transcriptional approach. Together, these results suggest that TXR may have therapeutic implications for hyperammonemic conditions in cholestatic livers.

NLRP3 inflammasome activation promotes liver inflammation and fibrosis in experimental biliary atresia

BACKGROUND

Biliary atresia (BA) is characterized by a progressive fibroinflammatory cholangiopathy in early infants with unknown etiology. Although innate immune disorder is involved in its mechanism, role of NLRP3 inflammasome in BA remains largely undefined.

AIM

To explore the role of NLRP3 inflammasome in BA.

METHODS

The expressions of NLRP3 inflammasome-related genes were determined in BA patients. Role of NLRP3 inflammasome was evaluated using MCC950 in experimental BA. Furthermore, gadolinium chloride, a macrophage scavenger, was applied to validate the inflammasome's cellular localization. Finally, the effects of NLRP3 inflammasome activation on liver fibrosis were explored in vivo and vitro in experimental BA.

RESULTS

The components of NLRP3 inflammasome were up-regulated in BA patients. Inflammasome-related genes showed positively correlated with liver inflammation and fibrosis in BA patients. In experimental BA, inflammasome-related genes were up-regulated, and their expressions were inhibited by MCC950, which promoted mice growth, protected liver function, alleviated obstructive jaundice, inhibited liver inflammation, and reduced serum IL-1β level. NLRP3 inflammasome was expressed in macrophages, and macrophage elimination exerted the same protective roles as MCC950 did in BA. Additionally, NLRP3 inflammasome activation promoted liver fibrosis in experimental BA.

CONCLUSIONS

NLRP3 inflammasome activation in macrophages promoted liver inflammation and fibrosis in experimental BA.

Therapeutic approaches for cholestatic liver diseases: the role of nitric oxide pathway

Cholestasis describes bile secretion or flow impairment, which is clinically manifested with fatigue, pruritus, and jaundice. Neutrophils play a crucial role in many diseases such as cholestasis liver diseases through mediating several oxidative and inflammatory pathways. Data have been collected from clinical, in vitro, and in vivo studies published between 2000 and December 2021 in English and obtained from the PubMed, Google Scholar, Scopus, and Cochrane libraries. Although nitric oxide plays an important role in the pathogenesis of cholestatic liver diseases, excessive levels of NO in serum and affected tissues, mainly synthesized by the inducible nitric oxide synthase (iNOS) enzyme, can exacerbate inflammation. NO induces the inflammatory and oxidative processes, which finally leads to cell damage. We found that natural products such as baicalin, curcumin, resveratrol, and lycopene, as well as chemical likes ursodeoxycholic acid, dexamethasone, rosuvastatin, melatonin, and sildenafil, are able to markedly attenuate the NO production and iNOS expression, mainly through inducing the nuclear factor κB (NF-κB), Janus kinase and signal transducer and activator of transcription (JAK/STAT), and toll like receptor-4 (TLR4) signaling pathways. This study summarizes the latest scientific data about the bile acid signaling pathway, the neutrophil chemotaxis recruitment process during cholestasis, and the role of NO in cholestasis liver diseases. Literature review directed us to propose that suppression of NO and its related pathways could be a therapeutic option for preventing or treating cholestatic liver diseases.

Unraveling the complexities of fibrosis and ductular reaction in liver disease: pathogenesis, mechanisms, and therapeutic insights

Ductular reaction and fibrosis are hallmarks of many liver diseases including primary sclerosing cholangitis, primary biliary cholangitis, biliary atresia, alcoholic liver disease, and metabolic dysfunction-associated steatotic liver disease/metabolic dysfunction-associated steatohepatitis. Liver fibrosis is the accumulation of extracellular matrix often caused by excess collagen deposition by myofibroblasts. Ductular reaction is the proliferation of bile ducts (which are composed of cholangiocytes) during liver injury. Many other cells including hepatic stellate cells, hepatocytes, hepatic progenitor cells, mesenchymal stem cells, and immune cells contribute to ductular reaction and fibrosis by either directly or indirectly interacting with myofibroblasts and cholangiocytes. This review summarizes the recent findings in cellular links between ductular reaction and fibrosis in numerous liver diseases.

Technical optimization of spatially resolved single-cell transcriptomic datasets to study clinical liver disease

Single cell and spatially resolved 'omic' techniques have enabled deep characterization of clinical pathologies that remain poorly understood, providing unprecedented insights into molecular mechanisms of disease. However, transcriptomic platforms are costly, limiting sample size, which increases the possibility of pre-analytical variables such as tissue processing and storage procedures impacting RNA quality and downstream analyses. Furthermore, spatial transcriptomics have not yet reached single cell resolution, leading to the development of multiple deconvolution methods to predict individual cell types within each transcriptome 'spot' on tissue sections. In this study, we performed spatial transcriptomics and single nucleus RNA sequencing (snRNAseq) on matched specimens from patients with either histologically normal or advanced fibrosis to establish important aspects of tissue handling, data processing, and downstream analyses of biobanked liver samples. We observed that tissue preservation technique impacts transcriptomic data, especially in fibrotic liver. Single cell mapping of the spatial transcriptome using paired snRNAseq data generated a spatially resolved, single cell dataset with 24 unique liver cell phenotypes. We determined that cell-cell interactions predicted using ligand-receptor analysis of snRNAseq data poorly correlated with cellular relationships identified using spatial transcriptomics. Our study provides a framework for generating spatially resolved, single cell datasets to study gene expression and cell-cell interactions in biobanked clinical samples with advanced liver disease.

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.

Long-term clinical and socioeconomic outcomes of children with biliary atresia

Background

Biliary atresia (BA) is rare liver disease of unknown etiology, and is a major indication for liver transplant (LT). Previous data indicate improved outcomes with early referral for Kasai portoenterostomy (KPE).

Objective

Evaluate the long-term outcomes in BA, with particular focus on those transitioned to adult care with native livers.

Subjects and Methods

Patients with BA treated between1980 and 2012 were identified. Data were collected from the time of referral, transition to adult care, and the most recent clinic notes, from which patient and native liver survival were calculated.

Results

Four hundred and fifty-four patients with BA were identified, who were followed up for median of 16.4 years from birth; 74 died (41 of whom had a LT), giving a 20-year survival rate of 83.6%. Two hundred and seventy-two patients received an LT, with the median native liver survival being 35 months. Of patients who transitioned to adult care, 54 of 180 (30.0%) retained their native liver. Of these, 72% (39 of 54) had evidence of chronic liver disease at transition, of whom 8 were subsequently lost to follow-up, 9 were transplanted, and 22 remained stable with compensated liver disease. Of the 15 of 54 patients (28%) with no evidence of chronic disease in their native liver disease at transition, 3 were subsequently lost to follow-up; none received transplants, although 3 patients developed new-onset liver disease. All patients transitioned to adult care completed secondary school education (N = 180), with 49% having attended college/university and 87% being in employment or education at the last follow-up. Of female patients, 34% had at least one pregnancy (27 children in 21 women), while 22% of males had fathered a child.

Conclusion

Long-term outcomes in BA are good, with patients surviving into adult life. Progression of chronic liver disease and associated morbidity is common in those who retained their native livers, suggesting that these patients require monitoring of liver disease throughout adult life, and early recognition of the need for LT.

Does amyloid β precursor protein gene expression have a role in diagnosis of biliary atresia?

Aim of the study

Biliary atresia (BA) is an important cause of surgical jaundice. Although the precise etiology is unknown, β-amyloid (Aβ) has been observed around the bile ducts in BA livers. It is unclear whether Aβ plays a role in the pathogenesis of this disease. This study aims to assess the amyloid β precursor protein (APP) gene expression in infants with BA in comparison with other causes of neonatal cholestasis. This could help explore the role of Aβ in the pathogenesis and diagnosis of BA.

Material and methods

A prospective study was conducted at the outpatient clinic of Paediatric Hepatology, Gastroenterology, and Nutrition Department, National Liver Institute, Menoufia University, Shebin El Kom, Menoufia, Egypt during the period March 2022 to December 2022. Clinical data were gathered and laboratory and radiological investigations were conducted including β precursor protein gene expression measured in liver biopsies of the three groups using quantitative real-time PCR (qPCR).

Results

Gene expression of APP was considerably higher in the BA group (p = 0.0001) compared to neonatal cholestasis (NC) patients. Gamma glutamyl transferase (GGT) and APP had a positive correlation (p = 0.001). No significant association was found between APP and fibrosis. APP was noticeably higher in BA than NC other than BA. Also, APP in BA was higher (statistically significant, p = 0.0001) than the control. There was no statistically significant difference among NC, BA, and control groups regarding APP (p = 0.07). Both males and females did not show significant differences as regards APP (p = 0.851). Age did not have a statistically significant correlation with APP (p = 0.532). Also, there were no correlations between APP and alkaline phosphatase (ALP), aspartate transaminase (AST), or total bilirubin (TB) (p > 0.05).

Conclusions

We concluded that the development and identification of BA may depend on the liver expression of serum APP. Surgeons may be able to carry out early intraoperative cholangiography for BA confirmation if the combination of APP with GGT and other hepatic function parameters exhibits a high predictive potential as a diagnostic test for BA. To evaluate this hypothesis, more research with sizable sample numbers is necessary.

The association of immune-related genes and the potential role of IL10 with biliary atresia

BACKGROUND

Biliary atresia (BA) is a severe immune-related disease that is characterized by biliary obstruction and cholestasis. The etiology of BA is unclear, our aim was to explore the relationship between biliary tract inflammation and immune-related genes.

METHODS

We selected 14 SNPs in 13 immune-related genes and investigated their associations with BA by using a large case‒control cohort with a total of 503 cases and 1473 controls from southern China.

RESULTS

SNP rs1518111 in interleukin10 (IL10) was identified as associated with BA (P = 5.79E-03; OR: 0.80; 95% CI: 0.68-0.94). The epistatic effects of the following pairwise interactions among these SNPs were associated with BA: signal transducer and activator of transcription 4 (STAT4) and chemokine (C-X-C motif) ligand 3 (CXCL3); STAT4 and damage-regulated autophagy modulator1 (DRAM1); CXCL3 and RAD51 paralog B (RAD51B); and interferon gamma (IFNG) and interleukin26 (IL26). Furthermore, we explored the potential role of IL-10 in the pathogenesis of the neonatal mouse model of BA. IL-10 effectively prevented biliary epithelial cell injury and biliary obstruction in murine BA as well as inhibit the activation of BA-related immune cells.

CONCLUSIONS

In conclusion, this study provided strong evidence implicating IL10 as a susceptibility gene for BA in the southern Chinese population.

IMPACT

This study provided strong evidence implicating IL10 as a susceptibility gene for BA in the southern Chinese population. This study could infer that IL-10 may play a protective role in BA mouse model. We found that four SNPs (rs7574865, rs352038, rs4622329, and rs4902562) have genetic interactions.

Predictive model containing gene signature and shear wave elastography to predict patient outcomes after Kasai surgery in biliary atresia

AIMS

Infants with biliary atresia (BA) are treated with Kasai portoenterostomy (KPE) surgery, but many BA patients need subsequent salvage liver transplants. The aim of this study is to develop a comprehensive gene-clinical model based on two-dimensional shear wave elastography (2DSWE), liver gene expression, and other clinical parameters to predict response to KPE for BA patients.

METHODS

Differentially expressed gene patterns between liver samples of BA (n = 102) and non-BA control (n = 14) were identified using RNA sequencing analysis. Biliary atresia patients were then randomly assigned to training and validation cohorts. Gene classifier based on the differentially expressed genes was built in the training cohort. Nomogram models with and without gene classifier were further constructed and validated for predicting native liver survival of BA patients. The utility of the nomograms was compared by C-index.

RESULTS

Using the least absolute shrinkage and selection operator model, we generated a nine-gene prognostic classifier. The nomogram based on the nine-gene classifier, age, preoperative 2DSWE, and albumin had the better C-index compared to gene classifier alone in the training cohort (0.83 [0.76-0.90] vs. 0.69 [0.61-0.77], p = 0.003) and the validation cohort (0.74 [0.67-0.82] vs. 0.62 [0.55-0.70], p = 0.001). Using risk scores developed from the nomogram, the 12-month survival rates of BA patients with native liver were 35.7% (95% confidence interval [CI], 22.7-56.3) in the high-risk group and 80.8% (95% CI, 63.4-100.0) in the low-risk group in the validation cohort.

CONCLUSIONS

The comprehensive genetic-clinical nomogram based on preoperative 2DSWE, liver gene expression, and other clinical parameters can accurately predict response to KPE.

Novel NIR-II fluorescent probes for biliary atresia imaging

Biliary atresia is a rare infant disease that predisposes patients to liver transplantation and death if not treated in time. However, early diagnosis is challenging because the clinical manifestations and laboratory tests of biliary atresia overlap with other cholestatic diseases. Therefore, it is very important to develop a simple, safe and reliable method for the early diagnosis of biliary atresia. Herein, a novel NIR-II fluorescence probe, HZL2, with high quantum yield, excellent biocompatibility, low cytotoxicity and rapid excretion through the liver and gallbladder was developed based on the oil/water partition coefficient and permeability. A simple fecal sample after injection of HZL2 can be used to efficiently identify the success of the mouse model of biliary atresia for the first time, allowing for an early diagnosis of the disease. This study not only developed a simple and safe method for the early diagnosis of biliary atresia with great potential in clinical translation but also provides a research tool for the development of pathogenesis and therapeutic medicines for biliary atresia.

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.

Plasticity between type 2 innate lymphoid cell subsets and amphiregulin expression regulates epithelial repair in biliary atresia

BACKGROUND AND AIMS

Although a dysregulated type 1 immune response is integral to the pathogenesis of biliary atresia, studies in both humans and mice have uncovered a type 2 response, primarily driven by type 2 innate lymphoid cells. In nonhepatic tissues, natural type 2 innate lymphoid cell (nILC2s) regulate epithelial proliferation and tissue repair, whereas inflammatory ILC2s (iIlC2s) drive tissue inflammation and injury. The aim of this study is to determine the mechanisms used by type 2 innate lymphoid cell (ILC2) subpopulations to regulate biliary epithelial response to an injury.

APPROACH AND RESULTS

Using Spearman correlation analysis, nILC2 transcripts, but not those of iILC2s, are positively associated with cholangiocyte abundance in biliary atresia patients at the time of diagnosis. nILC2s are identified in the mouse liver through flow cytometry. They undergo expansion and increase amphiregulin production after IL-33 administration. This drives epithelial proliferation dependent on the IL-13/IL-4Rα/STAT6 pathway as determined by decreased nILC2s and reduced epithelial proliferation in knockout strains. The addition of IL-2 promotes inter-lineage plasticity towards a nILC2 phenotype. In experimental biliary atresia induced by rotavirus, this pathway promotes epithelial repair and tissue regeneration. The genetic loss or molecular inhibition of any part of this circuit switches nILC2s to inflammatory type 2 innate lymphoid cell-like, resulting in decreased amphiregulin production, decreased epithelial proliferation, and the full phenotype of experimental biliary atresia.

CONCLUSIONS

These findings identify a key function of the IL-13/IL-4Rα/STAT6 pathway in ILC2 plasticity and an alternate circuit driven by IL-2 to promote nILC2 stability and amphiregulin expression. This pathway induces epithelial homeostasis and repair in experimental biliary atresia.

Panic at the Bile Duct: How Intrahepatic Cholangiocytes Respond to Stress and Injury

In the liver, biliary epithelial cells (BECs) line intrahepatic bile ducts (IHBDs) and are primarily responsible for modifying and transporting hepatocyte-produced bile to the digestive tract. BECs comprise only 3% to 5% of the liver by cell number but are critical for maintaining choleresis through homeostasis and disease. To this end, BECs drive an extensive morphologic remodeling of the IHBD network termed ductular reaction (DR) in response to direct injury or injury to the hepatic parenchyma. BECs are also the target of a broad and heterogenous class of diseases termed cholangiopathies, which can present with phenotypes ranging from defective IHBD development in pediatric patients to progressive periductal fibrosis and cancer. DR is observed in many cholangiopathies, highlighting overlapping similarities between cell- and tissue-level responses by BECs across a spectrum of injury and disease. The following core set of cell biological BEC responses to stress and injury may moderate, initiate, or exacerbate liver pathophysiology in a context-dependent manner: cell death, proliferation, transdifferentiation, senescence, and acquisition of neuroendocrine phenotype. By reviewing how IHBDs respond to stress, this review seeks to highlight fundamental processes with potentially adaptive or maladaptive consequences. A deeper understanding of how these common responses contribute to DR and cholangiopathies may identify novel therapeutic targets in liver disease.

Biliary atresia and liver transplantation in the United States: A contemporary analysis

BACKGROUND

Biliary atresia (BA) remains the number one indication for paediatric liver transplantation (LT) worldwide but is an uncommon indication for older LT recipients. The impact of recent donor allocation changes, pervasive organ shortage and evolving LT practices on the BA LT population is unknown.

METHODS

We identified patients who underwent LT between January 2010 and December 2021 using the UNOS database. We compared clinical outcomes between patients with BA and those with non-BA cholestatic liver disease. Groups were stratified by age, <12 years (allocated via PELD system) and ≥12 years (allocated via MELD system). Waitlist outcomes were compared using competing-risk regression analysis, graft survival rates were compared using Kaplan-Meier time-to-event analysis and Cox proportional hazards modelling provided adjusted estimates.

RESULTS

There were 2754 BA LT waitlist additions and 2206 BA LTs (1937 <12 years [younger], 269 ≥12 years [older]). There were no differences in waitlist mortality between BA and non-BA cholestatic patients. Among BA LT recipients, there were 441 (20.0%) living-donor liver transplantations (LDLT) and 611 (27.7%) split deceased-donor LTs. Five-year graft survival was significantly higher among BA versus non-BA cholestatic patients in the older group (88.3% vs. 79.5%, p < .01) but not younger group (89.3% vs. 89.5%). Among BA LT recipients, improved graft outcomes were associated with LDLT (vs. split LT: HR: 2, 95% CI: 1.03-3.91) and higher transplant volume (volume >100 vs. <40 BA LTs: HR: 3.41, 95% CI: 1.87-6.2).

CONCLUSION

Liver transplant outcomes among BA patients are excellent, with LDLT and higher transplant centre volume associated with optimal graft outcomes.

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

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

Zebrafish as a Useful Model System for Human Liver Disease

Liver diseases represent a significant global health challenge, thereby necessitating extensive research to understand their intricate complexities and to develop effective treatments. In this context, zebrafish (Danio rerio) have emerged as a valuable model organism for studying various aspects of liver disease. The zebrafish liver has striking similarities to the human liver in terms of structure, function, and regenerative capacity. Researchers have successfully induced liver damage in zebrafish using chemical toxins, genetic manipulation, and other methods, thereby allowing the study of disease mechanisms and the progression of liver disease. Zebrafish embryos or larvae, with their transparency and rapid development, provide a unique opportunity for high-throughput drug screening and the identification of potential therapeutics. This review highlights how research on zebrafish has provided valuable insights into the pathological mechanisms of human liver disease.

Technical optimization of spatially resolved single-cell transcriptomic datasets to study clinical liver disease

Single cell and spatially resolved 'omic' techniques have enabled deep characterization of clinical pathologies that remain poorly understood, providing unprecedented insights into molecular mechanisms of disease. However, transcriptomic platforms are costly, limiting sample size, which increases the possibility of pre-analytical variables such as tissue processing and storage procedures impacting RNA quality and downstream analyses. Furthermore, spatial transcriptomics have not yet reached single cell resolution, leading to the development of multiple deconvolution methods to predict individual cell types within each transcriptome 'spot' on tissue sections. In this study, we performed spatial transcriptomics and single nucleus RNA sequencing (snRNASeq) on matched specimens from patients with either histologically normal or advanced fibrosis to establish important aspects of tissue handling, data processing, and downstream analyses of biobanked liver samples. We observed that tissue preservation technique impacts transcriptomic data, especially in fibrotic liver. Deconvolution of the spatial transcriptome using paired snRNASeq data generated a spatially resolved, single cell dataset with 24 unique liver cell phenotypes. We determined that cell-cell interactions predicted using ligand-receptor analysis of snRNASeq data poorly correlated with celullar relationships identified using spatial transcriptomics. Our study provides a framework for generating spatially resolved, single cell datasets to study gene expression and cell-cell interactions in biobanked clinical samples with advanced liver disease.

Deletion of Interferon Lambda Receptor Elucidates Susceptibility to the Murine Model of Biliary Atresia

Biliary atresia (BA) is a life-threatening cholangiopathy occurring in infancy, the most common indication for pediatric liver transplantation. The etiology of BA remains unknown; however, a viral etiology has been proposed as multiple viruses have been detected in explants of infants afflicted with BA. In the murine model of BA, Rhesus rotavirus (RRV) infection of newborn BALB/c pups results in a cholangiopathy that mirrors human BA. Infected BALB/c pups experience 100% symptomatology and mortality, while C57BL/6 mice are asymptomatic. Interferon-λ (IFN-λ) is an epithelial cytokine that provides protection against viral infection. We demonstrated that IFN-λ is highly expressed in C57BL/6, leading to reduced RRV replication. RRV-infection of C57BL/6 IFN-λ receptor knockout (C57BL/6 IFN-λR KO) pups resulted in 90% developing obstructive symptoms and 45% mortality with a higher viral titer in bile ducts and profound periportal inflammation compared to C57BL/6. Histology revealed complete biliary obstruction in symptomatic C57BL/6 IFN-λR KO pups, while C57BL/6 ducts were patent. These findings suggest that IFN-λ is critical in preventing RRV replication. Deficiency in IFN-λ permits RRV infection, which triggers the inflammatory cascade causing biliary obstruction. Further IFN-λ study is warranted as it may play an important role in infant susceptibility to BA.

Frequency of infiltrating regulatory T-cells in the portal tract of biliary atresia

PURPOSE

Immunological abnormalities have been hypothesized as a pathogenesis of biliary atresia (BA). We previously investigated the frequency and function of circulating regulatory T-cells (Tregs) and reported no differences compared to controls. However, the local Treg profile remains uncertain. We aimed to investigate the frequency of Tregs in BA liver tissues.

METHODS

The number of lymphocytes, CD4+ cells, and CD4+FOXP3+ Tregs infiltrating the portal tract and the percentage of Tregs among CD4+ cells of BA and control patients were visually counted. The correlation between these data and clinical indicators was also examined.

RESULTS

The number of lymphocytes, CD4+ cells, and CD4+FOXP3+ Tregs was higher in the BA group. However, the percentage of Tregs among CD4+ cells was similar in both groups. Each parameter was correlated with serum γ-GTP, but there was no clear association with liver fibrosis, jaundice clearance, and native liver survival.

CONCLUSION

The number of Tregs infiltrating the portal tract was higher in BA patients. However, the infiltration of lymphocytes was also generally increased. Tregs appear to be unsuccessful in suppressing progressive inflammation in BA patients, despite recruitment to local sites. Investigation of Treg function in the local environment is warranted.

APRI and FIB-4 indices as diagnostic noninvasive scores for prediction of severe fibrosis in patients with biliary atresia

Aim of the study

Biliary atresia (BA) is a blockage in the tubes (ducts) that carry bile from the liver to the gallbladder. The aspartate aminotransferase to platelet ratio (APRI), and Fibrosis-4 (FIB-4) scores are commonly used compound surrogates for advanced fibrosis. However, the use of APRI and FIB-4 entails a risk of overestimating the fibrosis stage due to the impact of necroinflammatory activity on transaminases. So, we determined the optimal cutoff values of the APRI and FIB-4 indices in prediction of fibrosis in BA patients. The aim of the study was to evaluate the validity of the APRI and FIB-4 indices in prediction of fibrosis in patients with BA.

Material and methods

A cross sectional hospital-based study was conducted on 121 children complaining of BA attending the National Liver Institute, Menoufia University, Shebin Elkom, Menoufia, Egypt, during the period from January 2022 to February 2023.

Results

The APRI score was significantly higher among neglected BA than BA type II a, BA type III, type II b and type I (p = 0.001). Also FIB-4 was significantly higher among neglected BA than BA type II a, BA type II b, type III and type I (p = 0.001). Receiver operating characteristic (ROC) curve analysis showed that the cutoff point of the APRI score in prediction of fibrosis in patients with BA was 1.29, with sensitivity of 88.6% and specificity of 76.0%, while the cutoff point of FIB-4 in prediction of fibrosis in patients with BA was 9.82 with sensitivity of 89.0% and specificity of 70.0%.

Conclusions

Our study confirms that FIB-4 and APRI scores are both able to predict severe fibrosis. APRI score and FIB-4 are good non-invasive alternatives to liver biopsy in the detection of liver fibrosis and its extent in patients with BA.

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.

Matrix Metalloproteinase-7 and Osteopontin Serum Levels as Biomarkers for Biliary Atresia

OBJECTIVES

Matrix metallopeptidase-7 (MMP-7) and osteopontin (OPN) are important components in the pathophysiology of fibrosis in biliary atresia (BA). There has been much recent interest in MMP-7 serum level in the diagnosis of BA. We aimed to assess the diagnostic accuracy and prognostic value of both MMP-7 and OPN in a Western BA study.

METHODS

Diagnostic value was assessed by comparison of serum MMP-7 and OPN levels in infants with BA and age-matched cholestatic controls. Prognostic value was assessed through subsequent clearance of jaundice (COJ) and need for liver transplantation (LT).

RESULTS

Serum was assessed from 32 BA and 27 controls. Median MMP-7 was higher in BA (96.4 vs 35 ng/mL; P < 0.0001) with an optimal cut-off value of 69 ng/mL. Sensitivity and specificity was 68% and 93%, respectively [negative predictive value (NPV) = 71%]. Similarly, median OPN was higher in BA (1952 vs 1457 ng/mL; P = 0.0001) and an optimal cut-off of 1611 ng/mL. Sensitivity and specificity was 84% and 78%, respectively (NPV = 81%). MMP-7 level correlated positively with Ishak liver fibrosis score (r = 0.27, P = 0.04). Neither MMP-7 (70 vs 100 ng/mL; P = 0.2) nor OPN (1969 vs 1939 ng/mL; P = 0.3) were predictive of COJ, or need for LT (99 vs 79 ng/mL; P = 0.7, and 1981 vs 1899 ng/mL; P = 0.2), respectively.

CONCLUSIONS

MMP-7 and OPN may have contributory value in the diagnosis of BA, but remain far of the "gold standard" role. Much more prospective data are required and collaborative multi-center initiatives should be the next logical steps.

Exome-wide assessment of isolated biliary atresia: A report from the National Birth Defects Prevention Study using child-parent trios and a case-control design to identify novel rare variants

The etiology of biliary atresia (BA) is unknown, but recent studies suggest a role for rare protein-altering variants (PAVs). Exome sequencing data from the National Birth Defects Prevention Study on 54 child-parent trios, one child-mother duo, and 1513 parents of children with other birth defects were analyzed. Most (91%) cases were isolated BA. We performed (1) a trio-based analysis to identify rare de novo, homozygous, and compound heterozygous PAVs and (2) a case-control analysis using a sequence kernel-based association test to identify genes enriched with rare PAVs. While we replicated previous findings on PKD1L1, our results do not suggest that recurrent de novo PAVs play important roles in BA susceptibility. In fact, our finding in NOTCH2, a disease gene associated with Alagille syndrome, highlights the difficulty in BA diagnosis. Notably, IFRD2 has been implicated in other gastrointestinal conditions and warrants additional study. Overall, our findings strengthen the hypothesis that the etiology of BA is complex.

Genetic alterations and molecular mechanisms underlying hereditary intrahepatic cholestasis

Hereditary cholestatic liver disease caused by a class of autosomal gene mutations results in jaundice, which involves the abnormality of the synthesis, secretion, and other disorders of bile acids metabolism. Due to the existence of a variety of gene mutations, the clinical manifestations of children are also diverse. There is no unified standard for diagnosis and single detection method, which seriously hinders the development of clinical treatment. Therefore, the mutated genes of hereditary intrahepatic cholestasis were systematically described in this review.

Development of liver inflammatory injury in biliary atresia: from basic to clinical research

Biliary atresia (BA) is a severe cholangiopathy in infants. It is characterized by inflammatory fibro-obliteration of the intra- and extrahepatic bile ducts. Although the restoration of bile flow can be successful after Kasai operation, the rapid progression of liver fibrosis can continue, leading to cirrhosis. It is believed that the progression of liver fibrosis in BA is exacerbated by complicated mechanisms other than the consequence of bile duct obstruction. The fibrogenic cascade in BA liver can be divided into three stages, including liver inflammatory injury, myofibroblast activation, and fibrous scar formation. Recent studies have revealed that the activation of an immune response following bile duct injury plays an important role in promoting the inflammatory process, the releasing of inflammatory cytokines, and the development of fibrogenesis in BA liver. In this article, we summarized the evidence regarding liver inflammatory injury and the possible mechanisms that explain the rapid progression of liver fibrosis in BA.

Association analysis and functional follow-up identified common variants of JAG1 accounting for risk to biliary atresia

Background: Biliary atresia (BA) is a destructive, obliterative cholangiopathy characterized by progressive fibro-inflammatory disorder and obliteration of intra- and extrahepatic bile ducts. The Jagged1 (JAG1) gene mutations have been found in some isolated BA cases. We aim to explore the association of common variants in JAG1 with isolated BA risk in the Chinese Han population. Methods: We genotyped 31 tag single nucleotide polymorphisms covering the JAG1 gene region in 333 BA patients and 1,665 healthy controls from the Chinese population, and performed case-control association analysis. The expression patterns of JAG1 homologs were investigated in zebrafish embryos, and the roles of jag1a and jag1b in biliary development were examined by morpholino knockdown in zebrafish. Results: Single nucleotide polymorphisms rs6077861 [P _Allelic = 1.74 × 10^-4, odds ratio = 1.78, 95% confidence interval: 1.31-2.40] and rs3748478 (P _Allelic = 5.77 × 10^-4, odds ratio = 1.39, 95% confidence interval: 1.15-1.67) located in the intron region of JAG1 showed significant associations with BA susceptibility. The JAG1 homologs, jag1a and jag1b genes were expressed in the developing hepatobiliary duct of zebrafish, especially at 72 and 96 h postfertilization. Knockdown of both jag1a and jag1b led to poor biliary secretion, sparse intrahepatic bile duct network and smaller or no gallbladders compared with control embryos in the zebrafish model. Conclusion: Common genetic variants of JAG1 were associated with BA susceptibility. Knockdown of JAG1 homologs led to defective intrahepatic and extrahepatic bile ducts in zebrafish. These results suggest that JAG1 might be implicated in the etiology of BA.

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-An experience from the first pediatric liver transplant center in Pakistan

BACKGROUND

Biliary atresia (BA) is the most common cause of neonatal cholestatic syndrome. The true incidence of BA in Pakistan is largely unknown.

AIM

This study aimed to report the clinical features, age at diagnosis and outcomes of biliary atresia from the first pediatric liver transplant center in Pakistan.

METHODS

The study was done in Shifa International hospital from 2013 to 2020. All babies who had biliary atresia confirmed by laboratory investigation were included. Demographic data, age of presentation, clinical presentation, supporting investigations like liver function tests, ultrasound abdomen, HIDA scan and liver biopsy were noted. Outcome related to Kasai portoenterostomy, liver transplant, complications and immunosuppressant agents were noted.

RESULT

A total of 42 children were included, 23 (54.7%) males and 19 (45.2%) were females. Jaundice was seen in all patients (100%) followed by acholic stools (81%). Associated malformations were noted in 6 (14.2%) patients. Liver function tests confirmed obstructive cholestasis (p 0.04). Kasai was done in 19 (45%) patients only, living donor liver transplant was performed in 6 (14%) patients. Age range of transplant patients was from 3 months to 1 year. Indication for liver transplant was failed Kasai in 1(16.7%) patient and chronic liver disease in 5 (83.3%) patients. LDLT survivors were 10 months to 1 year of age at the time of transplant, mean age was 10.6 months. Maximum survival noted so far is 7 years. Acute complications seen post-transplant were sepsis (three patients), surgical site infections (two patients), biliary leaks and acute cellular rejection in one patient each. Chronic graft rejection, portal vein stricture needing stenting was done in one patient.

DISCUSSION

All patients underwent LDLT from related donors wih no donor related mortality. All are deceased patients were yonger and had advanced disease. BA remains third most commo indication of transplant in our center.

CONCLUSION

Liver transplant is the only lifesaving procedure after failed Kasai or as primary liver transplant due to advance liver disease. The advent of liver transplantation services offers survival and improving outlook of the disease.

Identifying and validating molecular subtypes of biliary atresia using multiple high-throughput data integration analysis

Background

Biliary atresia (BA) is the most common form of severe neonatal obstructive jaundice. The etiology and pathogenesis of BA are multifactorial, and different factors may interact to produce heterogeneous pathological features and clinical outcomes. Despite different pathological features, all patients received the same treatment strategy. This study performed integrative clustering analysis based on multiple high-throughput datasets to identify the molecular subtypes of BA and provide a new treatment strategy for personalized treatment of the different subtypes of BA.

Methods

The RNA sequence dataset GSE122340 in the Gene Expression Omnibus (GEO) database was downloaded; 31 BA and 20 control normal liver tissues were collected at our center for transcriptome sequencing, and clinical and follow-up data of BA patients were available. Molecular subtypes were identified using integrated unsupervised cluster analysis involving gene expression, biliary fibrosis, and immune enrichment scores based on the transcriptome dataset, and the results were validated using independent datasets.

Results

Based on the results of the integrated unsupervised clustering analysis, four molecular subtypes were identified: autoimmune, inflammatory, virus infection-related, and oxidative stress. The autoimmune subtype with a moderate prognosis was dominated by autoimmune responses and morphogenesis, such as the Fc-gamma receptor and Wnt signaling pathway. The biological process of the inflammatory subtype was mainly the inflammatory response, with the best prognosis, youngest age at surgery, and lowest liver stiffness. The virus infection-related subtype had the worst prognosis and was enriched for a variety of biological processes such as viral infection, immunity, anatomical morphogenesis, and epithelial mesenchymal transition. The oxidative stress subtype was characterized by the activation of oxidative stress and various metabolic pathways and had a poor prognosis. The above results were verified independently in the validation sets.

Conclusions

This study identified four molecular subtypes of BA with distinct prognosis and biological processes. According to the pathological characteristics of the different subtypes, individualized perioperative and preoperative treatment may be a new strategy to improve the prognosis of BA.

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.

Integrative analysis implicates the significance of m6A in the liver fibrosis of biliary atresia by regulating THY1

Whether N6-methyladenosine (m6A) is involved in biliary atresia (BA) remains undefined. Herein, we comprehensively evaluated the m6A profile in BA. When compared with normal controls, BA had an elevated m6A level with upregulated m6A writers. The m6A level was correlated with liver function, stage of fibrosis and jaundice clearance in BA. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) demonstrated an altered m6A topology in BA. MeRIP-seq and RNA sequencing filtered out 130 m6A-modified genes, which were enriched in fibrogenetic pathways. MeRIP-qPCR in vivo and interventions of LX-2 and primary HSCs in vitro validated the regulatory role of m6A on COL1A1 and THY1. THY1+ myofibroblasts expanded in portal area of BA, and highly expressed profibrogenic genes (COL1A1, MMP2, PDGFRA, and DCN). THY1 was correlated with liver fibrosis and jaundice clearance in BA. Bulk array (GSE46960, GSE15235), single-cell RNA sequencing (GSE136103), primary HSC interventions, and co-immunoprecipitation revealed that THY1 was correlated with extracellular matrix organization, promoted HSC activation, showed higher interactions with integrins on myeloid cells in cholestatic fibrosis, and was correlated with native liver survival in BA. Our study highlights the significance of m6A in BA-induced liver fibrogenesis by regulating THY1, shedding new light on the novel therapies to alleviate liver fibrosis by targeting m6A/THY1 axis in BA.

Biliary Atresia Splenic Malformation: A Case Report from A Tertiary Centre in West Africa and the Lessons Learnt

Biliary atresia (BA) is a rare disease characterised by biliary obstruction of unknown origin that presents in the neonatal period. It is classified into syndromic with various congenital anomalies and non-syndromic (isolated anomaly). We present a case of syndromic BA associated with polysplenia and intestinal malrotation, discovered incidentally during the Kasai procedure. The small intestine was found to be non-rotated with the duodenojejunal junction to the right of the vertebral column. The presence of accessory spleens was noted. Kasai portoenterostomy and Ladd's procedure were performed. The patient had an uneventful postoperative course with the passage of cholic stool from the third postoperative day. At the seventh-month follow-up, the stool remained cholic. A multidisciplinary approach in the care of babies with BA and long-term follow-up is crucial for a successful outcome.

Bioinformatics analysis identifies heparan sulfate proteoglycans acting as different progress subtypes of biliary atresia

BACKGROUND

Biliary atresia (BA) is a life-threatening disorder, which is characterized by the obliteration of biliary tracts. Heparan sulfate proteoglycans (HSPGs) are important regulators in liver diseases. Whether HSPGs participate in the development of BA is poorly understood.

METHODS

RNA-seq dataset GSE122340, including 171 BA and 7 normal liver tissue, was integrated for bioinformatic analysis. R function "wilcox.test" was used to compare HSPGs expression levels, and "cor.test" was used to evaluate the correlation analysis. MCPcounter was used to assess the abundance of immunocytes. Molecular subtypes of BA were clustered via NMF clustering and LASSO regression was applied to screen hub HSPGs genes in BA clusters. RT-PCR analysis was used to assess the expression of hub HSPGs in BA liver. Immunohistochemical staining and immunofluorescence assay were used to evaluated the location and expression of hub HSPGs in BA liver tissue.

RESULTS

Majority of HSPGs was up-regulated in BA and correlated with liver fibrosis and ductular reaction markers. The abundance of immunocytes was higher in BA and associated with HSPGs. Based on the expression of HSPGs, BA patients were classified into 3 subtypes (C1, C2, and C3). Pathway enrichment analysis revealed C1 subtype had severe liver injury with SDC4 identified as the hub gene, while C3 subtype presented relatively normal liver condition with GPC3 identified as the hub gene. RT-PCR analysis demonstrated the expression levels of 2 hub genes in BA liver tissue with different jaundice clearance standards. Immunohistochemical staining and immunofluorescence assay showed that SDC4 was mostly expressed in ductular reaction area, while GPC3 was mostly expressed in hepatocytes.

CONCLUSION

Majority of HSPGs are aberrant expressed in BA. The subtype hub gene SDC4 and GPC3 might be used as a potential indicator for different types of prognosis.

Human poliovirus receptor contributes to biliary atresia pathogenesis by exacerbating natural-killer-cell-mediated bile duct injury

BACKGROUND AND AIMS

Natural killer (NK) cells play an important role in biliary atresia (BA) pathogenesis; human poliovirus receptor (PVR) is an important NK-cell modulator. Here, we explored the role of PVR in BA pathogenesis.

METHODS

Poliovirus receptor expression and NK cell-associated genes were detected in human BA samples and a rotavirus-induced BA mouse model using quantitative PCR and immunofluorescence staining. Chemically modified small interfering RNA silenced PVR expression in the BA model, and its effects on the population and function of intrahepatic NK cells were investigated using flow cytometry (FCM). The effects of PVR overexpression and knockdown on proliferation, apoptosis and NK-cell-mediated lysis of cultured human cholangiocytes were analysed using FCM and cell viability assays. Serum PVR, high-mobility group box 1 (HMGB1), and interleukin-1beta (IL-1beta) levels were measured in a cohort of 50 patients using ELISA.

RESULTS

Poliovirus receptor expression was upregulated in the biliary epithelium of BA patients and BA model and was positively correlated with the population and activation of intrahepatic NK cells. Silencing of PVR expression impaired the cytotoxicity of NK cells, reduced inflammation and protected mice from rotavirus-induced BA. Activation of the TLR3-IRF3 signalling pathway induced PVR expression in cultured cholangiocytes. PVR overexpression promoted proliferation and inhibited the apoptosis of cholangiocytes but exacerbated NK cell-mediated cholangiocyte lysis. Serum PVR levels were elevated in BA patients and were positively correlated with HMGB1 and IL-1beta levels.

CONCLUSIONS

Poliovirus receptor contributes to BA pathogenesis by regulating NK cell-mediated bile duct injury; PVR has the value as a biomarker of BA.