Etiology of biliary atresia as a developmental anomaly: recent advances

Congenital biliary atresia caused by GPC1 gene mutation in Chinese siblings: A case report

BACKGROUND

Congenital biliary atresia (CBA) is a serious hepatobiliary disease in children with unknown etiology. Its outcome is often liver transplantation or death. Clarifying the etiology of CBA is of great significance for prognosis, treatment, and genetic counseling.

CASE SUMMARY

A male Chinese infant at an age of 6 mo and 24 d was hospitalized because of "yellow skin for more than 6 mo". Soon after birth, the patient developed jaundice, which then progressively intensified. A "laparoscopic exploration" indicated "biliary atresia". After coming to our hospital, genetic testing suggested a GPC1 mutation [loss 1 (exons 6-7)]. The patient recovered and was discharged after living donor liver transplantation. After discharge, the patient was followed up. The condition was controlled by oral drugs, and the patient’s condition was stable.

CONCLUSION

CBA is a complex disease with a complex etiology. Clarifying the etiology is of great clinical importance for treatment and prognosis. This case reports CBA caused by a GPC1 mutation, which enriches the genetic etiology of biliary atresia. However, its specific mechanism needs to be confirmed by further research.

The Bioinformatic Study Uncovers Probable Critical Genes Involved in the Pathophysiology of Biliary Atresia

Background

Biliary atresia (BA) is an uncommon illness that causes the bile ducts outside and within the liver to become clogged in babies. If left untreated, the cholestasis causes increasing conjugated hyperbilirubinemia, cirrhosis, and hepatic failure. BA has a complicated aetiology, and the mechanisms that drive its development are unknown. The objective of this study was to show the role of probable critical genes involved in the pathophysiology of biliary atresia.

Methods

We utilised the public Gene Expression Omnibus (GEO) microarray expression profiling dataset GSE46960 to find differentially expressed genes (DEGs) in 64 biliary atresia newborns, 14 infants with various causes of intrahepatic cholestasis, and 7 deceased-donor children as control subjects in our study. The relevant information was looked into. The important modules were identified after functional enrichment, GO and KEGG pathway analyses, protein-protein interaction (PPI) network analyses, and GSEA analysis.

Results

The differential expression analysis revealed a total of 22 elevated genes. To further understand the biological activities of the DEGs, we run functional enrichment analyses on them. Meanwhile, KEGG analysis has revealed significant enrichment of pathways involved in activating cross-talking with inflammation and fibrosis in BA. SERPINE1, THBS1, CCL2, MMP7, CXCL8, EPCAM, VCAN, ITGA2, AREG, and HAS2, which may play a significant regulatory role in the pathogenesis of BA, were identified by PPI studies.

Conclusion

Our findings suggested 10 hub genes and probable mechanisms of BA in the current study through bioinformatic analysis.

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.

Glial Cell Line-Derived Neurotrophic Factor, S-100 Protein and Synaptophysin Expression in Biliary Atresia Gallbladder Tissue

PURPOSE

Biliary atresia (BA) is a disease that manifests as jaundice after birth and leads to progressive destruction of the ductal system in the liver. The aim of this study was to investigate histopathological changes and immunohistochemically examine the expression of glial cell line-derived neurotrophic factor (GDNF), synaptophysin, and S-100 protein in the gallbladder of BA patients.

METHODS

The study included a BA group of 29 patients and a control group of 41 children with cholecystectomy. Gallbladder tissue removed during surgery was obtained and examined immunohistochemically and histopathologically. Tissue samples of both groups were immunohistochemically assessed in terms of GDNF, S-100 protein, and synaptophysin expression. Expression was classified as present or absent. Inflammatory activity assessment with hematoxylin and eosin staining and fibrosis assessment with Masson's trichrome staining were performed for tissue sample sections of both groups.

RESULTS

Ganglion cells were not present in gallbladder tissue samples of the BA group. Immunohistochemically, GDNF, synaptophysin, and S-100 expression was not detected in the BA group. Histopathological examination revealed more frequent fibrosis and slightly higher inflammatory activity in the BA than in the control group.

CONCLUSION

We speculate that GDNF expression will no longer continue in this region, when the damage caused by inflammation of the extrahepatic bile ducts reaches a critical threshold. The study's findings may represent a missing link in the chain of events forming the etiology of BA and may be helpful in its diagnosis.

Whole exome sequencing analysis for mutations in isolated type III biliary atresia patients

Aim of the study

Biliary atresia is an idiopathic, destructive disease that affects both extrahepatic and intrahepatic bile ducts with severe inflammation and manifests as progressive jaundice within the first few months of life. In this study, we aimed to investigate the significance of genetic mutations in the onset of biliary atresia disease.

Material and methods

With the approval of the ethics committee and parental consent, blood was taken from patients to obtain their DNA, and the study commenced. In this prospective study, we examined the DNA of 10 patients with no disease other than biliary atresia, and an exome sequence analysis was performed with the new-generation DNA sequencing method. The genetic structure of biliary atresia disease was examined by statistical analysis of the mutations, which were determined according to the reference DNA sequencing.

Results

In the exome sequence analysis, the number of mutations detected among the patients changed significantly; the lowest number was 12,591, and the maximum was 19,863. By examining these mutations, we identified the mutated genes that were common to all patients.

Conclusions

In this study, the highest mutation rates were detected in the PRIM2 and MAP2K3 genes. These genes have not previously been associated with biliary atresia.

Systems Analysis of Biliary Atresia Through Integration of High-Throughput Biological Data

Biliary atresia (BA), blockage of the proper bile flow due to loss of extrahepatic bile ducts, is a rare, complex disease of the liver and the bile ducts with unknown etiology. Despite ongoing investigations to understand its complex pathogenesis, BA remains the most common cause of liver failure requiring liver transplantation in children. To elucidate underlying mechanisms, we analyzed the different types of high-throughput genomic and transcriptomic data collected from the blood and liver tissue samples of children suffering from BA. Through use of a novel integrative approach, we identified potential biomarkers and over-represented biological functions and pathways to derive a comprehensive network showing the dysfunctional mechanisms associated with BA. One of the pathways highlighted in the integrative network was hypoxia signaling. Perturbation with hypoxia inducible factor activator, dimethyloxalylglycine, induced the biliary defects of BA in a zebrafish model, serving as a validation for our studies. Our approach enables a systems-level understanding of human BA biology that is highlighted by the interaction between key biological functions such as fibrosis, inflammation, immunity, hypoxia, and development.

Association of common variation in ADD3 and GPC1 with biliary atresia susceptibility

Biliary atresia (BA) is an idiopathic neonatal cholestatic disease. Recent genome-wide association study (GWAS) revealed that common variation of ADD3, GPC1, ARF6, and EFEMP1 gene was associated with BA susceptibility. We aimed to evaluate the association of these genes with BA in Chinese population. Twenty single nucleotide polymorphisms (SNPs) in these four genes were genotyped in 340 BA patients and 1,665 controls. Three SNPs in ADD3 were significantly associated with BA, and rs17095355 was the top SNP (P_Allele = 3.23×10^-6). Meta-analysis of published data and current data indicated that rs17095355 was associated with BA susceptibility in Asians and Caucasians. Three associated SNPs were expression quantitative trait loci (eQTL) for ADD3. Two GPC1 SNPs in high linkage disequilibrium (LD) showed nominal association with BA susceptibility (P_Allele = 0.03 for rs6707262 and P_Allele = 0.04 for rs6750380), and were eQTL of GPC1. Haplotype harboring these two SNPs almost reached the study-wide significance (P = 0.0035). No association for ARF6 and EFEMP1 was found with BA risk in the current population. Our study validated associations of ADD3 and GPC1 SNPs with BA risk in Chinese population and provided evidence of epistatic contributions of genetic factors to BA susceptibility.

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

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

Biliary atresia: pathology, etiology and pathogenesis

Biliary atresia is a progressive fibrosing obstructive cholangiopathy of the intrahepatic and extrahepatic biliary system, resulting in obstruction of bile flow and neonatal jaundice. Histopathological findings in liver biopsies include the expansion of the portal tracts, with edematous fibroplasia and bile ductular proliferation, with bile plugs in duct lumen. Lobular morphological features may include variable multinucleate giant cells, bilirubinostasis and hemopoiesis. The etiopathogenesis of biliary atresia is multifactorial and multiple pathomechanisms have been proposed. Experimental and clinical studies have suggested that viral infection initiates biliary epithelium destruction and release of antigens that trigger a Th1 immune response, which leads to further injury of the bile duct, resulting in inflammation and obstructive scarring of the biliary tree. It has also been postulated that biliary atresia is caused by a defect in the normal remodelling process. Genetic predisposition has also been proposed as a factor for the development of biliary atresia.

A Morphology-based Analysis of Biliary Ductules After Kasai Procedure and a Review of the Literature

OBJECTIVE

To explore the distribution of biliary ductules in biliary remnants of patients with biliary atresia and to investigate the relationship between the ductules and the prognosis after Kasai portoenterostomy.

PATIENTS AND METHODS

From October 01, 2015 to September 30, 2017, 46 patients who were diagnosed as type 3 biliary atresia were enrolled in this study. Continuous sections of biliary remnants were stained with cytokerantin 19 antibody. The number, area, and distribution of micro-biliary ductules of each section were recorded. According to the number of ductules in the most proximal section (n ≥ 20 or n < 20), patients were divided into two groups (A or B) and followed up for 1-3 y, including cholangitis, jaundice clearance, and survival with native liver.

RESULTS

Four patients had no micro-biliary ductules. In 17 patients with ductules, the numbers at bilateral parts were similar (P > 0.05), while the ductules in the middle part were significantly less than bilateral parts (P < 0.05). Starting from 2 mm from the proximal end of remnants, the number of ductules significantly and gradually decreased (P < 0.05). The total area of ductules in Group A was significantly increased compared to that in Group B (P < 0.05). Patients in Group A had significantly higher jaundice clearance rate and better survival rate with native liver than patients in Group B (both, P < 0.05). Patients had significantly higher incidence of cholangitis in Group A compared to Group B (P < 0.05).

CONCLUSIONS

The number/area of ductules yielded by technical precision is closely related to effective bile drainage, jaundice clearance, and first onset of cholangitis in patients after Kasai procedure.

Suppressing microRNA-29c promotes biliary atresia-related fibrosis by targeting DNMT3A and DNMT3B

This study was designed to investigate the potential role of microRNA-29c (miR-29c) in biliary atresia-related fibrosis. The expression of miR-29c was determined in 15 pairs of peripheral blood samples from infants with biliary atresia (BA) and infants with non-BA neonatal cholestasis using quantitative real-time PCR. EMT was established by induction with TGF-β1 in HIBEpiC cells. MiR-29c was inhibited by lipofectamine transfection. The expressions of proteins related to epithelial-mesenchymal transition (EMT), i.e., E-cadherin, N-cadherin and vimentin, were determined using quantitative real-time PCR and western blotting. Direct interaction between miR-29c and DNMT3A and DNMT3B was identified using a luciferase reporter assay. The expressions of DNMT3A and DNMT3B were suppressed by treatment with SGI-1027. Patients with BA showed significantly lower miR-29c levels in peripheral blood samples than the control subjects. In vitro, TGF-β1-induced EMT significantly decreased the expression of miR-29c. Downregulation of miR-29c had a promotional effect on BA-related fibrosis in HIBEpiC cells, as confirmed by the decrease in E-cadherin and increase in N-cadherin and vimentin levels. MiR-29c was found to target the 3'UTR of DNMT3A and DNMT3B and inhibit their expression. Suppression of DNMT3A and DNMT3B reversed the effects of miR-29c downregulation on BA-related fibrosis in HIBEpiC cells. These data suggest that BA-related fibrosis is closely associated with the occurrence of EMT in HIBEpiC cells. MiR-29c might be a candidate for alleviating BA-related fibrosis by targeting DNMT3A and DNMT3B.

Transcription factor GATA6: a novel marker and putative inducer of ductal metaplasia in biliary atresia

Biliary atresia (BA), a neonatal liver disease, is characterized by obstruction of extrahepatic bile ducts with subsequent cholestasis, inflammation, and progressive liver fibrosis. To gain insights into the pathophysiology of BA, we focused attention on GATA6, a transcription factor implicated in biliary development. Early in fetal development GATA6 expression is evident in cholangiocytes and hepatocytes, but by late gestation it is extinguished in hepatocytes. Utilizing a unique set of BA liver samples collected before and after successful portoenterostomy (PE), we found that GATA6 expression is markedly upregulated in hepatocytes of patients with BA compared with healthy and cholestatic disease controls. This upregulation is recapitulated in two murine models simulating bile duct obstruction and intrahepatic bile ductule expansion. GATA6 expression in BA livers correlates with two established negative prognostic indicators (age at PE, degree of intrahepatic bile ductule expansion) and decreases after normalization of serum bilirubin by PE. GATA6 expression in BA livers correlates with expression of known regulators of cholangiocyte differentiation ( JAGGED1, HNF1β, and HNF6). These same genes are upregulated after enforced expression of GATA6 in human hepatocyte cell models. In conclusion, GATA6 is a novel marker and a putative driver of hepatocyte-cholangiocyte metaplasia in BA, and its expression in hepatocytes is downregulated after successful PE. NEW & NOTEWORTHY A pathological hallmark in the liver of patients with biliary atresia is ductular reaction, an expansion of new bile ductules that are thought to arise from conversion of mature hepatocytes. Here, we show that transcription factor GATA6 is a marker and potential driver of hepatocyte ductal metaplasia in biliary atresia. Hepatocyte GATA6 expression is elevated in biliary atresia, correlates with bile duct expansion, and decreases after successful portoenterostomy.

Hepatic Hilar Lymph Node Reactivity at Kasai Portoenterostomy for Biliary Atresia: Correlations With Age, Outcome, and Histology of Proximal Biliary Remnant

We hypothesized that if infection is the proximate cause of congenital biliary atresia, an appropriate response to antigen would occur in lymph nodes contiguous with the biliary remnant. We compared the number of follicular germinal centers (GC) in 79 surgically excised hilar lymph nodes (LN) and 27 incidentally discovered cystic duct LNs in 84 subjects at the time of hepatic portoenterostomy (HPE) for biliary atresia (BA) to autopsy controls from the pancreaticobiliary region of non-septic infants >3 months old at death. All 27 control LN lacked GC, a sign in infants of a primary response to antigenic stimulation. GC were found in 53% of 106 LN in 56 of 84 subjects. Visible surgically excised LN contiguous with the most proximal biliary remnants had 1 or more well-formed reactive GC in only 26/51 subjects. Presence of GC and number of GC/LN was unrelated to age at onset of jaundice or to active fibroplasia in the biliary remnant but was related to older age at HPE. Absent GC in visible and incidentally removed cystic duct LNs predicted survival with the native liver at 2 and 3 years after HPE, P = .03, but significance was lost at longer intervals. The uncommon inflammatory lesions occasionally found in remnants could be secondary either to bile-induced injury or secondary infection established as obstruction evolves. The absence of consistent evidence of antigenic stimulation in LN contiguous with the biliary remnant supports existence of at least 1 major alternative to infection in the etiology of biliary atresia.

The coming of age of a young subspecialty: paediatric hepatology

Paediatric hepatology dates from the 1970s and it is the youngest of the organ-specific subspecialties. As then there have been impressive achievements in the fields of anatomical, metabolic, immunological and neoplastic diseases, and the advent of modern molecular biology has resulted in a marked increase in exact diagnoses. Liver transplants provided enormous stimulus for the discipline. Due to changing morbidity patterns, the discipline faces new challenges, such as environment- and lifestyle-induced liver diseases, but different forms of chronic viral hepatitis are diminishing.

CONCLUSION

High levels of competence require good clinical research, optimal results and a high degree of centralisation.

Biliary Atresia - Clinical Series

Introduction

Biliary atresia is the main cause of death by hepatic failure and the main indication for liver transplant in children. This study aims to analyze the population with this diagnosis, treated between 2000 and 2015 at Hospital de São João.

Material and Methods

Descriptive, observational, and retrospective study, including the patients with biliary atresia, diagnosed and treated between January 1, 2000 and December 31, 2015. We analyzed epidemiologic, clinical, biochemical, and image data, as well as registered complications and present status.

Results

Eighteen patients were evaluated. The median age at time of Kasai portoenterostomy was 63 days of life, with better prognosis for those patients who had surgery before 72 days. The procedure was successful in 2/3 of cases. There was a significant association between recurrent cholangitis and survival. Five cases of transplant and 2 deaths, one of them after transplant, were registered. Survival with native liver was 77.8%, 72.2%, and 64.2% at 1, 5, and 10 years of follow-up, respectively.

Discussion

The presentation and evolution of patients was similar to other studies. However, there was a higher surgical success and survival rates at 5 and 10 years of follow-up than most series. Age at surgery and recurrence of cholangitis were the only factors significantly related to prognosis.

Conclusion

In spite of the low number of patients (1,125/year), our results were similar to those of other reference centers.

Association of common genetic variants in VEGFA with biliary atresia susceptibility in Northwestern Han Chinese

Biliary atresia (BA) is a major neonatal obliterative cholangiopathy, resulting in progressive cirrhosis. The gene VEGFA encodes a heparin-binding protein that is a regulator of angiogenesis and a mediator of inflammatory reactions, and accumulating evidence have indicated that VEGFA may play a possible role in the pathogenesis of BA. Our study aim was to evaluate the association of common variants within the VEGFA gene with BA susceptibility in Northwestern Han Chinese population. Forty tag SNPs within the VEGFA gene were selected in the study, and then subsequently genotyped in 1336 Northwestern Han Chinese individuals, consisting of 311 BA patients and 1025 healthy controls. The SNP rs3025039 was found to be strongly associated with BA risk (additive P=0.000264) in our sample, and the CC genotype of rs3025039 had higher prevalence than the other two genotypes, indicating the C allele is a risk allele with an odds ratio (OR) of 1.56 and 95% confidence interval (CI) of 1.23-1.99. Haplotype analyses showed that a LD block containing rs3025039 significantly correlated with BA risk (global P<0.001). Moreover, bioinformatics analysis indicated that hsa-mir-591 and VEGFA formed miRNA/SNP target duplexes if the rs3025039 allele was in the T form, suggesting that rs3025039 may alter VEGFA expression by affecting hsa-miR-591/single-nucleotide polymorphism target duplexes. Our results indicate additional evidence supporting that there is an important role of the VEGFA gene in the increased susceptibility of BA.

ABBREVIATIONS

Macrophage Migration Inhibitory Factor (MIF) Gene Promotor Polymorphism Is Associated with Increased Fibrosis in Biliary Atresia Patients, but Not with Disease Susceptibility

Two polymorphisms, rs755622 and rs5844572, in the promoter region of the macrophage migration inhibitory factor (MIF) gene influence the basal and/or induced transcriptional activity and have been linked to several inflammatory and autoimmune diseases. The aim of this study was to investigate the association between these two polymorphisms and disease susceptibility in patients with biliary atresia (BA). Allele frequencies of rs755622 and rs5844572 were assessed in 60 Egyptian infants with a confirmed diagnosis of BA. DNA was extracted from archival material. For the rs755622, samples were tested using Taqman real-time PCR, and for the rs5844572, samples were tested using fluorescence-based genotyping. The allele frequency in the general population was assessed in 141 healthy adults from the same geographical location. No statistical differences were observed in the allele frequencies of either rs755622 or rs5844572 between BA patients and controls. The homozygous and heterozygous short repeats (5/5, or 5/X) of rs5844572 were observed more frequently (16/28, 57.1%) in BA patients with mild to moderate fibrosis compared with those with marked fibrosis (10/32, 31.3%). The difference was statistically significant (P  =  0.032). In conclusion, we observed no association between MIF rs755622 and rs5844572 polymorphisms and susceptibility to BA; however, the rs5844572 could be linked to the rate of progression of the disease and extent of fibrosis.

Embryonic cholecystitis and defective gallbladder contraction in the Sox17-haploinsufficient mouse model of biliary atresia

The gallbladder excretes cytotoxic bile acids into the duodenum through the cystic duct and common bile duct system. Sox17 haploinsufficiency causes biliary atresia-like phenotypes and hepatitis in late organogenesis mouse embryos, but the molecular and cellular mechanisms underlying this remain unclear. In this study, transcriptomic analyses revealed the early onset of cholecystitis in Sox17^+/- embryos, together with the appearance of ectopic cystic duct-like epithelia in their gallbladders. The embryonic hepatitis showed positive correlations with the severity of cholecystitis in individual Sox17^+/- embryos. Embryonic hepatitis could be induced by conditional deletion of Sox17 in the primordial gallbladder epithelia but not in fetal liver hepatoblasts. The Sox17^+/- gallbladder also showed a drastic reduction in sonic hedgehog expression, leading to aberrant smooth muscle formation and defective contraction of the fetal gallbladder. The defective gallbladder contraction positively correlated with the severity of embryonic hepatitis in Sox17^+/- embryos, suggesting a potential contribution of embryonic cholecystitis and fetal gallbladder contraction in the early pathogenesis of congenital biliary atresia.

Forkhead box A3 attenuated the progression of fibrosis in a rat model of biliary atresia

Biliary atresia is a rare, devastating disease of infants where a fibroinflammatory process destroys the bile ducts, leading to fibrosis and biliary cirrhosis, and death if untreated. The cause and pathogenesis remain largely unknown. We tried to investigate factors involved in biliary atresia, especially forkhead box A3 (Foxa3), which might exert a role in the treatment of liver disease. We used RNA sequencing to sequence the whole transcriptomes of livers from six biliary atresia and six choledochal cysts patients. Then, we employed a rat disease model by bile duct ligation (BDL) and adenovirus transduction to address the function of Foxa3 in biliary atresia. We found that tight junction, adherence junction, cell cycle, apoptosis, chemokine singling, VEGF and MAPK signaling pathways were enriched in biliary atresia livers. We showed that Foxa3 expression was notably decreased in liver samples from biliary atresia patients. More importantly, we found that its lower expression predicted a poorer overall survival of biliary atresia patients. Rats that received BDL surgery and Foxa3 expression adenovirus resulted in a significant decrease in the deposition of collagen, and expression of profibrotic cytokines (transforming growth factor-β and connective tissue growth factor) and fibrosis markers (α-smooth muscle actin, collagen I and collagen III), as compared with rats that received BDL surgery and control adenovirus. Our data suggested a protection role for Foxa3 during the progression of liver fibrosis in biliary atresia, and thereby supported increasing Foxa3 as a targeted treatment strategy.

Achondroplasia and Biliary Atresia: A Rare Association and Review of Literature

Achondroplasia (ACH) occurs in most cases as de novo mutations of the gene-encoding fibroblast growth factor receptor 3 (FGFR3). Biliary atresia (BA) is a progressive neonatal inflammatory and fibro-obliterative cholangiopathy affecting the extra- and intrahepatic biliary tree to varying degrees, and it results in obstruction to bile flow and cholestatic jaundice in neonates. BA is thought to be a multifactorial disease, genome association studies have shown abnormalities in susceptibility genes, and levels of fibroblast growth factor 21 (FGF21) and fibroblast growth factor 23 (FGF23) have been noted to be increased. These two conditions occurring in the same patient has never been reported before.

Association between rs17095355 polymorphism on 10q24 and susceptibility to biliary atresia: a meta-analysis

OBJECTIVE

Recent studies have identified 10q24-rs17095355 as a susceptibility locus for biliary atresia (BA). To more precisely estimate the association between the rs17095355 polymorphism and BA risk, a meta-analysis was performed.

METHODS

A comprehensive search was conducted to examine all the eligible studies by electronic databases including Elsevier Science Direct, Pubmed, Google Scholar, China National Knowledge Infrastructure (CNKI) and Chinese Biomedical Literature (CBM) up to December 2015. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of the association.

RESULTS

A total of 6 comparisons from 5 relevant studies involving 1000 patients and 3257 controls were included to analyze the association between rs17095355 and BA risk. The pooled OR for T allele of rs17095355 was 1.72 (95%CI 1.53-1.92, p < 0.01) in BA. Stratification by ethnicity indicated the degree of risk of rs17095355 with BA susceptibility was similar in populations of Asian origin. The pooled OR was 1.81 (95%CI 1.60-2.06, p < 0.01).

CONCLUSIONS

This meta-analysis confirms the association of rs17095355 polymorphism and BA development, especially in Asians. More original studies with large sample are needed to replicate this genetic association in different ethnic groups.

Contribution of acoustic radiation force impulse (ARFI) elastography to the ultrasound diagnosis of biliary atresia

BACKGROUND

Children with biliary atresia rapidly develop liver fibrosis secondary to inflammatory destruction of the biliary tract. Noninvasive detection of liver fibrosis in neonatal/infantile cholestasis is an additional criterion for the diagnosis of biliary atresia, leading to prompt surgical exploration.

OBJECTIVE

To assess the value of US with acoustic radiation force impulse (ARFI) elastography to detect biliary atresia in the workup of neonatal/infantile cholestasis.

MATERIALS AND METHODS

In this retrospective study, 20 children with cholestasis suspected of having biliary atresia were investigated by US and ARFI. We evaluated the association between US findings and the diagnosis of biliary atresia and with two scores of liver fibrosis obtained from liver biopsy.

RESULTS

In univariate analyses, gallbladder size, triangular cord sign, spleen size and ARFI values were found to be associated with biliary atresia, though only the triangular cord sign remained significant when elevated gamma glutamyltransferase (GGT) was included as a predictor. In contrast, spleen size and ARFI correlated with the degree of liver fibrosis on biopsy (r > 0.70, P < 0.001), which remained significant when gamma glutamyltransferase elevation was included as a predictor.

CONCLUSION

The addition of ARFI to a standard abdominal US in the initial workup of the neonate with possible infantile cholestasis can provide reliable information on liver fibrosis and help in the diagnosis of biliary atresia.

Screening of targeted genes in extrahepatic bile ducts of mice with experimental biliary atresia

Biliary atresia (BA) is an infantile disease resulting from a severe cholangiopathy, which can obstruct extrahepatic bile ducts, disrupt bile flow and lead to end‑stage cirrhosis. The current study aimed to develop a genetic method to investigate the pathogenesis of BA. The gene expression profile of BA (GSE46967) was downloaded from the Gene Expression Omnibus database and included 18 samples from newborn mice. These samples were collected at three time points following the induction of BA with rhesus rotavirus. The differentially expressed genes (DEGs) in mice with BA were identified using the limma package in R language, followed by hierarchical clustering analysis. Gene ontology functional analysis and Kyoto Enrichment of Genes and Genomes pathway analysis of the selected common DEGs was conducted using the Database for Annotation, Visualization and Integrated Discovery. In total, 306 DEGs were identified in the samples from the 3 day time point, 721 at 7 days and 370 at 14 days. A total of 74 common DEGs were identified in these three sample groups, which are reported to function in multiple immune biological processes, including the defense response, leukocyte migration, cell chemotaxis and leukocyte chemotaxis. In addition, 'cytokine‑cytokine receptor interaction' and 'chemokine signaling pathway' were observed to be significantly enriched in BA. A total of six common DEGs (CCL3, CXCL5, CXCL13, CXCR2, CCL5 and CCL6) were identified that were involved in the significantly enriched functions and the significantly enriched pathways. The data from the current study suggested that the immune response is a critical biological process in the development of BA. The six critical hub genes identified (CCL3, CXCL5, CXCL13, CXCR2, CCL5 and CCL6) may be used as specific target genes in the treatment of BA.

Genetic contributors and modifiers of biliary atresia

To date, the etiology and pathogenic underpinning of the progression of the most prevalent serious neonatal liver disease, biliary atresia, remains elusive. This disease presents as an aggressive form of neonatal cholestasis characterized by the destruction and obliteration of the extrahepatic bile ducts within the first few weeks of life and a rapid progression of biliary fibrosis, likely due to unremitting cholestasis and retention of biliary constituents including bile acids. In ∼5% of patients, biliary atresia is associated with laterality features, suggesting a genetic underpinning to a disease that begins soon after birth. However, biliary atresia does not occur within families and twins are discordant, indicating an absence of strict mendelian inheritance. Despite this, genes related to bile duct dysmorphogenesis/ciliopathies overlapping with features of biliary atresia in both humans and nonhuman model systems have been proposed. Taken together, strict genetic etiologies leading to a common pathway of a neonatal cholangiopathy resulting in biliary atresia remain elusive. Contributions from fibrogenesis- and inflammation-based studies suggest that early engagement of these pathways contributes to disease progression, but a recent double-blind study did not suggest any benefit from early use of corticosteroids. However, there are genetic contributions to the adaptation and response to cholangiopathies and cholestasis that may be present in certain populations that likely impact upon the response to hepatoportoenterostomy and subsequent biliary tract function. Studies utilizing next generation sequencing technologies (e.g., exome analysis) are ongoing in several laboratories around the world; they are expected to provide insights into genetic contributions to biliary atresia outcomes. Altogether, combinations of exome sequencing and large population studies are expected to reveal causative and modifying genes relevant to patients with biliary atresia as a means to provide therapeutic targets and potential opportunities for genetic screening.

Genome-wide association studies in biliary atresia

Biliary atresia (BA) is a model complex disease resulting from interactions between multiple susceptibility loci and environmental factors. This perception is based on a heterogeneous phenotype extending beyond an absent extrahepatic bile duct to include gut and cardiovascular anomalies, and the association of BA with viral infections. Refractory jaundice and progression to cirrhosis shortly after birth can be fatal without surgical correction, and further suggests a pathogenesis during liver and bile duct development. Conclusive proof for a developmental origin would require documentation of disease progression in the perinatal or fetal liver, an impossible task for obvious reasons. We review three different sets of genome-wide association studies (GWAS) from three different cohorts of BA patients by three different groups of investigators, which address this knowledge gap. Knockdown of each susceptibility gene identified by GWAS in zebrafish embryos impairs excretion of bile from the liver, duplicating the characteristic diagnostic finding seen in affected children. This finding is associated with impaired intrahepatic biliary network formation in zebrafish morphants. Although distinct, these susceptibility genes share several functions including roles in mechanisms for organogenesis (glypican 1 or GPC1, and adenosine diphosphate ribosylation factor 6, or ARF6) or a greater expression in fetal liver than in adult liver (adducin 3 or ADD3). Together, these studies emphasize the importance of the human evidence, and present opportunities to map novel pathways which explain the phenotypic heterogeneity of BA.

Ultrasonographic findings of type IIIa biliary atresia

Purpose:

To describe the ultrasonographic (US) findings of type IIIa biliary atresia.

Methods:

We retrospectively reviewed a medical database of patients pathologically confirmed to have biliary atresia, Kasai type IIIa, between January 2002 and May 2013 (n=18). We evaluated US findings including the visible common bile duct (CBD), triangular cord thickness, gallbladder size and shape, and subcapsular flow on color Doppler US; laboratory data; and pathological hepatic fibrosis grades. We divided them into two groups-those with visible (group A) and invisible (group B) CBD on US-and compared all parameters between the two groups.

Results:

CBD was visible on US in five cases (27.8%; group A) and invisible in 13 cases (72.2%; group B). US was performed at an earlier age in group A than in group B (median, 27 days vs. 60 days; P=0.027) with the maximal age of 51 days. A comparison of the US findings revealed that the triangular cord thickness was smaller (4.1 mm vs. 4.9 mm; P=0.004) and the gallbladder length was larger (20.0 mm vs. 11.7 mm; P=0.021) in group A. The gallbladder shape did not differ between the two groups, and the subcapsular flow was positive in all cases of both groups. There was no significant difference in the laboratory data between the two groups. Upon pathological analysis, group A showed low-grade and group B showed low- to high-grade hepatic fibrosis.

Conclusion:

When CBD is visible on US in patients diagnosed with type IIIa biliary atresia, other US features could have a false negative status. A subcapsular flow on the color Doppler US would be noted in the type IIIa biliary atresia patients.