Relationship between prognosis of biliary atresia and infection of cytomegalovirus

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

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

Biliary atresia

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

Incidence and antiviral treatment of cytomegalovirus infection in infants with biliary atresia

PURPOSE

Patients with biliary atresia (BA) and cytomegalovirus (CMV) infection may have poorer outcomes after Kasai portoenterostomy (KPE) than uninfected patients, suggesting a rationale for antiviral treatment (AVT). We aimed to describe the incidence of CMV infection and of AVT in BA patients, and to detect any differences between infected and uninfected patients to conclude if AVT is of use.

METHODS

Data on BA patients who underwent KPE 2004-2020 were retrospectively collected, and the outcome was analyzed with regard to CMV status.

RESULTS

Fifteen out of forty-six (33%) BA patients had signs of ongoing CMV infection. They did not differ significantly from the CMV-negative patients regarding rate of prematurity, birth weight, or biochemical markers but were slightly older at KPE. All patients received steroids postoperatively and all patients with ongoing CMV infection received AVT with very good effect on viremia and without major side effects. The AVT consisted of oral valganciclovir (10-40 (- 58) mg/kg/d) or intravenous ganciclovir (5.3-11 mg/kg/d).

CONCLUSION

Ongoing CMV infection is common in this group of patients. The viremia can effectively be treated with AVT without any major side effects. Larger, randomized studies are needed to clarify the possible effect on clinical outcome.

A Comparative Study Between Cytomegalovirus Immunoglobulin M-Positive and CMV Immunoglobulin M-Negative Biliary Atresia in Infants Attending a Tertiary Care Hospital in Bangladesh

PURPOSE

Perinatal cytomegalovirus (CMV) infection can lead to biliary atresia (BA) in different entities. This study aimed to compare the clinical, hematological, biochemical, and histological features of infants with BA based on their CMV immunoglobulin M (IgM) status at presentation.

METHODS

This cross-sectional descriptive study was carried out between January 2019 and June 2020 at the Department of Pediatric Gastroenterology and Nutrition at the Bangabandhu Sheikh Mujib Medical University (BSMMU) in Dhaka. Forty-three patients with BA were selected purposively and categorized into either the CMV IgM-positive or CMV IgM-negative BA group. Categorical variables were compared using Fisher's exact test and chi-square tests, while the Student's t-test and Mann-Whitney U-test were used to compare continuous variables. For all statistical tests, a p-value <0.05 was considered statistically significant.

RESULTS

Thirty-three (76.7%) of the cases were between 2 and 3 months of age on admission. The clinical, hematological, and biochemical parameters did not differ significantly between the CMV IgM-positive and CMV IgM-negative BA groups. Most (50.0%) of the CMV IgM-positive cases had fibrosis stage F2, while 43.5% of the CMV IgM-negative cases had fibrosis stage F3, with no significant difference between the groups (p=0.391).

CONCLUSION

Our data shows no significant distinction between CMV IgM-positive and CMV IgM-negative BA, suggesting that CMV does not contribute to BA pathogenesis.

Incidence, Impact and Treatment of Ongoing CMV Infection in Patients with Biliary Atresia in Four European Centres

Cytomegalovirus (CMV) infection has been suggested to be of importance for the development and outcome of biliary atresia (BA). However, most data are only available from single centre studies. We retrospectively collected data on rates, outcomes, and treatments for ongoing CMV infection at the time of Kasai portoenterostomy (KPE) from four different tertiary centres in Europe. The rate of ongoing CMV infection varied between 10–32% in the four centres. CMV positive patients were significantly older and had higher levels of several liver biochemistries at the time of KPE (p < 0.05 for all comparisons). In the largest centre, CMV infection was more common in non-Caucasians, and CMV infected patients had poorer long-term survival with native liver than CMV negative patients (p = 0.0001). In contrast, survival with native liver in the subgroup of CMV infected patients who had received antiviral treatment was similar to the CMV negative group. We conclude that ongoing CMV infection at the time of KPE occurs in a significant proportion of BA patients and that these patients seem to differ from CMV negative patients regarding age and biochemistry at the time of KPE as well as long-term survival with native liver. The latter difference may be reduced by antiviral treatment, but randomized, controlled trials are needed before such treatment can be recommended routinely.

Effects of cytomegalovirus infection on the differential diagnosis between biliary atresia and intrahepatic cholestasis in a Chinese large cohort study

INTRODUCTION AND OBJECTIVES

Differentiating biliary atresia from other causes of neonatal cholestasis is challenging, particularly when cytomegalovirus (CMV) and biliary atresia occur simultaneously. We aimed to elucidate whether CMV infection would affect the differential diagnosis of biliary atresia and intrahepatic cholestasis.

PATIENTS AND METHODS

This retrospective study was conducted among patients with neonatal cholestasis admitted to three tertiary hospitals between January 2010 and August 2019. The clinical characteristics, laboratory, and imaging findings were recorded. On the basis of the CMV serology results, the infants were classified into CMV-IgM (+) and CMV-IgM (-) groups. The clinical differences and diagnostic performances of routine predictors between biliary atresia and intrahepatic cholestasis were analyzed in each group. Finally, we compared the diagnostic performances of various tests in the two groups.

RESULTS

A total of 705 patients with neonatal cholestasis were enrolled: 215 (30.5%) patients were positive for CMV-IgM, among whom 97 had biliary atresia and 118 had CMV hepatitis; 490 infants were CMV-IgM (-), among whom 240 had biliary atresia and 250 had intrahepatic cholestasis. The diagnostic performances of stool color, direct bilirubin level, γ-glutamyl transpeptidase level, abnormal gallbladder, triangular cord sign, and hepatobiliary scintigraphy between CMV hepatitis and CMV-IgM (+) biliary atresia were similar to those between CMV-IgM (-) biliary atresia and CMV-IgM (-) intrahepatic cholestasis groups.

CONCLUSIONS

Our large-scale study showed a high prevalence of CMV infection in patients with neonatal cholestasis in China. The presence of CMV infection did not affect the routine predictors to discriminate biliary atresia and intrahepatic cholestasis.

A Novel Model for Predicting the Clearance of Jaundice in Patients With Biliary Atresia After Kasai Procedure

BACKGROUND

The failed clearance of jaundice (CJ) in patients with biliary atresia (BA) after the Kasai procedure (KP) often leads to a shorter native liver survival (NLS) time and earlier liver transplantation. We aimed to investigate risk factors of failed CJ and establish a novel nomogram model to predict the status of CJ.

METHODS

We retrospectively reviewed institutional medical records from January 2015 to April 2020 and enrolled BA patients post-KP, randomly divided into training and testing cohorts at a ratio of 7:3, and further subdivided into cleared and uncleared jaundice groups. Univariate and multiple logistic regression analyses were used to select risk factors to establish the nomogram in the training cohort. The performance of the nomogram was evaluated by calculating the areas under the receiver operating curve (AUC) in both cohorts.

RESULTS

This study included 175 BA patients post-KP. After univariate and multiple logistic regression analyses, Cytomegalovirus IgM +ve associated BA (OR = 3.38; 95% CI 1.01-11.32; P = 0.04), ln γ-glutamyl transpeptidase (GGT) (OR = 0.41; 95% CI 0.22-0.80; P = 0.009), thickness of the fibrous portal plate (OR = 0.45; 95% CI 0.27-0.76; P = 0.003), liver stiffness measurement (LSM) (OR = 1.19; 95% CI 1.06-1.34; P = 0.002), and multiple episodes of cholangitis (OR = 1.65; 95% CI 1.13-2.41; P = 0.01) were identified as independent risk factors of unsuccessful CJ to construct the nomogram. The receiver operating characteristic curve (ROC) analysis suggested good nomogram performance in both the training (AUC = 0.96) and testing cohorts (AUC = 0.91).

CONCLUSION

Our nomogram model including several risk factors effectively predicts CJ in patients post-KP, which could aid in clinical decision-making.

Detection of Cytomegalovirus Infection in Infants with Biliary Atresia: A Meta-analysis

Objectives  Biliary atresia (BA) is the most common indication of liver transplantation in children. Several reports attributed BA to both prenatal and perinatal etiologies, including a viral infection-induced autoimmune response that targets the bile ducts. Cytomegalovirus (CMV) remains the most common virus being linked to BA. This meta-analysis aimed to estimate to what extent CMV infection is detected in patients with BA.

Methods  This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The databases of MEDLINE, Embase, Scopus, WHO-Virtual Health Library (VHL), ScienceDirect, and Google Scholar were used for the systematic search. The risk of bias was assessed using the Newcastle–Ottawa scale. Random effects model was used to estimate the pooled prevalence estimate with the corresponding 95% confidence interval (CI) using Comprehensive Meta-Analysis Software version 3.3.

Results  A total of 19 studies that fulfilled the eligibility criteria were included in the meta-analysis. The total number of infants with BA was 630 patients, and the pooled overall prevalence of CMV infection among them was 25.4% (95% CI: 15.9%–38.0%). There was high heterogeneity among studies (I ²  = 85.1%, p  < .001), and subgroup analyses showed significant regional differences (X ²  = 48.9, p <.001). Data on the prognosis of CMV-associated BA were scarce and obtainable from few studies that suggested an association between detection of CMV infection and poor prognosis of BA.

Conclusions  The limited available data demonstrates that the rate of detection of CMV infection is high in infants with BA. There is still a need for large studies with appropriate controls for obtaining more reliable results about the various aspects of the association between CMV infection and BA.

Hepatic interferon γ and tumor necrosis factor a expression in infants with neonatal cholestasis and cytomegalovirus infection

Aim of the study

To determine the hepatic interferon γ (IFN-γ) and tumor necrosis factor α (TNF-α) levels in infants with neonatal cholestasis (NC) and associated cytomegalovirus (CMV) infection.

Material and methods

This study was conducted in 21 infants with NC over a period of 6 months from June 2017 to December 2017 to determine the hepatic IFN-γ and TNF-α levels in infants with NC and associated CMV infection.

Results

IFN-γ levels were positive in 16 (80%), low positive in 3 (16%) and negative in 1 (5%) patients. High positive and positive TNF-α levels were seen in 9 (56.3%) patients with positive liver CMV PCR and low positive levels were seen in 7 (43.7%) patients with positive liver CMV PCR (odds ratio [OR] = 2.6). Positive IFN-γ was present in 13 (81.3%) patients with positive liver CMV PCR and low positive or negative IFN-γ was seen in 3 (18.7%) patients with positive liver CMV PCR (OR = 2.2). Six (60%) patients with positive or high positive TNF-α levels in liver tissue had biliary atresia (BA) whereas 7 (77.7%) with low positive TNF-α levels had non-BA neonatal hepatitis (OR = 5.25). Six (37.5%) patients with positive IFN-γ had BA whereas 2 (50%) patients with low positive or negative IFN-γ had BA (OR = 0.6).

Conclusions

There is high prevalence of CMV in liver tissues in patients with NC and elevated TNF-α and IFN-γ levels are seen in these patients. Elevated TNF-α is also seen in patients with BA. The association of elevated TNF-α, BA and CMV infection needs to be evaluated further.

Unsupervised Clustering Reveals Distinct Subtypes of Biliary Atresia Based on Immune Cell Types and Gene Expression

BACKGROUND

Biliary atresia (BA) is a severe cholangiopathy of early infancy that destroys cholangiocytes, obstructs ductular pathways and if left untreated, culminates to liver cirrhosis. Mechanisms underlying the etiological heterogeneity remain elusive and few studies have attempted phenotyping BA. We applied machine learning to identify distinct subtypes of BA which correlate with the underlying pathogenesis.

METHODS

The BA microarray dataset GSE46995 was downloaded from the Gene Expression Omnibus (GEO) database. Unsupervised hierarchical cluster analysis was performed to identify BA subtypes. Then, functional enrichment analysis was applied and hub genes identified to explore molecular mechanisms associated with each subtype. An independent dataset GSE15235 was used for validation process.

RESULTS

Based on unsupervised cluster analysis, BA patients can be classified into three distinct subtypes: Autoimmune, Viral and Embryonic subtypes. Functional analysis of Subtype 1 correlated with Fc Gamma Receptor (FCGR) activation and hub gene FCGR2A, suggesting an autoimmune response targeting bile ducts. Subtype 2 was associated with immune receptor activity, cytokine receptor, signaling by interleukins, viral protein interaction, suggesting BA is associated with viral infection. Subtype 3 was associated with signaling and regulation of expression of Robo receptors and hub gene ITGB2, corresponding to embryonic BA. Moreover, Reactome pathway analysis showed Neutrophil degranulation pathway enrichment in all subtypes, suggesting it may result from an early insult that leads to biliary stasis.

CONCLUSIONS

The classification of BA into different subtypes improves our current understanding of the underlying pathogenesis of BA and provides new insights for future studies.

Prognosis of Biliary Atresia Associated With Cytomegalovirus: A Meta-Analysis

Objective: The etiology of biliary atresia is unclear, but viral infection has been implicated. The aim of the current meta-analysis was to investigate relationships between cytomegalovirus (CMV) and the prognosis of biliary atresia. Methods: PubMed, Embase, the Cochrane Library, the China National Knowledge Infrastructure database, and Wanfang Data electronic databases were searched for eligible studies. Each relevant text was thoroughly reviewed and examined, including related papers in their reference lists. Results: A total of nine studies including 784 patients were included in the analysis. Biliary atresia patients with CMV exhibited significantly lower jaundice clearance (odds ratio: 0.46, p < 0.0001; I ² = 15%, p = 0.31). There were no significant differences in the rates of cholangitis or native liver survival. CMV-pp65-positive biliary atresia patients had a significantly lower rate of jaundice clearance (odds ratio: 5.87, p = 0.003; I ² = 0%, p = 0.71) and a significantly higher rate of cholangitis (odds ratio: 0.21, p = 0.01; I ² = 0%, p = 0.43) than CMV antibody-positive biliary atresia patients. Conclusion: Biliary atresia patients who were also infected with CMV had a poorer prognosis, particularly with respect to jaundice clearance. CMV status may influence the prognosis of biliary atresia. Clinicians should be able to routinely identify the subset of biliary atresia patients who are also CMV-positive, in order to improve native liver survival.

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

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

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.

Evidence for Viral Induction of Biliary Atresia: A Review

Biliary atresia (BA) is a childhood disease which manifests with abnormal narrowing, blockage or complete absence of bile ducts within the liver. Many possible etiologies have been reported for the development of BA, including congenital, perinatal and acquired conditions. Since the 1970's, there has been increasing evidence linking BA development to viral perinatal infections. The viral vectors most commonly implicated include members of the herpesviridae family (cytomegalovirus and Epstein-Barr virus) as well as those of the reoviridae family (reovirus and rotavirus). While extensive work has been done on a murine model of disease, the current review focuses primarily on evidence from human studies of viral vectors in children afflicted with BA.

Detection of Cytomegalovirus in Liver Tissue by Polymerase Chain Reaction in Infants With Neonatal Cholestasis

AIM

Cytomegalovirus (CMV) is associated with neonatal cholestasis (NC). Diagnosis of CMV infection is most often based on either positive blood CMV IgM or CMV blood polymerase chain reaction (PCR). Isolation of CMV in liver tissues in patients with NC has rarely been reported. This study was undertaken to see if CMV is present in liver tissues of patients with NC and evaluate the correlation between positive CMV PCR in liver tissue with the serology and blood PCR.

METHODS

This study was conducted in 31 infants with NC from June 2015 to December 2016. All patients underwent blood CMV IgM, blood CMV PCR and liver CMV PCR. Prevalence of CMV in NC based on positive liver CMV PCR was calculated. Sensitivity and specificity of the serologic markers and blood CMV PCR to identify CMV infection in the liver was determined.

RESULTS

CMV IgM was positive in 13 (42%) patients, CMV IgG was positive in 26 (84%) patients and blood CMV PCR was positive in 23 (74%) patients. Liver CMV PCR was positive in 16 (52%) patients. Fifteen (48%) patients had biliary atresia (BA), 10 (32%) patients had neonatal hepatitis, 5 (16%) had paucity of bile ducts and 1 (3%) had ascending cholangitis. Of the 16 patients with positive liver CMV PCR, 8 (50%) had BA, 4 (25%) had neonatal hepatitis, 3 (19%) had paucity of bile ducts and 1 (6%) had ascending cholangitis. Sensitivity of blood CMV IgM in relation to liver CMV PCR was 69% and specificity was 61%. Sensitivity of blood CMV PCR was 61% and specificity was 71% when compared with liver CMV PCR.

CONCLUSION

CMV is present in the liver tissues of more than half the patients with NC. Serology or blood CMV PCR is apparently not an accurate marker of CMV in the liver tissue. Also, CMV infection in children seems to be associated equally with BA or non-BA neonatal hepatitis.

Update on investigations pertaining to the pathogenesis of biliary atresia

Biliary atresia is a devastating biliary disease of neonates that results in liver transplantation for the vast majority. The etiology of biliary atresia is unknown and is likely multifactorial, with components of genetic predisposition, environmental trigger and autoimmunity contributing to disease pathogenesis. This review highlights recent work related to investigations of disease pathogenesis in biliary atresia.

Adjuvant therapy in biliary atresia: hopelessly optimistic or potential for change?

Given that the aetiology of biliary atresia (BA) is complex and that there is a multiplicity of possible pathogenic mechanisms then it is perhaps not surprising that the evidence for effect of a number of different agents is contradictory. Post-operative cholangitis for instance is common, bacterial in origin and various antibiotic regimens have been tested (although none in a randomized trial) but continuation beyond the early post-operative period does not appear to offer any greater protection. There is an inflammatory reaction in about 25-35% of cases of BA illustrated by abnormal expression of class II antigen and upregulation of ICAM, VCAM and E-selectin with an infiltrate of immune-activated T cells (predominantly CD4 + Th1 and Th17) and NK cells and a systemic surge in inflammatory cytokines (e.g. TNF-α, IL-2, IL-12). This has potential as a therapeutic target and is the main hypothesis behind the rationale use of steroids. The first report of steroids was published in 1985 by Karrer and Lilly as "blast" therapy to treat recalcitrant cholangitis, followed by a multiplicity of small-scale uncontrolled studies suggesting benefit. To date there has been one randomized placebo-controlled study with a low-dose (prednisolone 2 mg/kg/day) regimen (2007); one with a high-dose (IV prednisolone 4 mg/kg/day regimen) (2014); two prospective high-dose open-label studies (2013); a prospective comparison of low- and high-dose regimen and a large (380 infants) retrospective comparison. The most recent meta-analysis (2016) identified a significant difference in clearance of jaundice at 6 months (OR 1.59, 95% CI 1.03-2.45, P = 0.04), in patients treated with high-dose steroids, particularly if < 70 days at surgery. Ursodeoxycholic acid (UDCA) may increase choleresis or change the ratio of endogenous bile acids to a less hydrophobic and, therefore, less toxic millieu. UDCA may protect cholangiocyte membranes against damage and perhaps reduce the tendency to fibrogenesis. Biochemical benefit has been shown in a single crossover trial in older BA children who had cleared their jaundice. Other potential adjuvant therapies include immunoglobulin therapy, anti-viral agents and Chinese herbs although real evidence of benefit is lacking.

Surgical outcome and etiologic heterogeneity of infants with biliary atresia who received Kasai operation less than 60 days after birth: A retrospective study

This study aimed to analyze the impact of etiologic heterogeneity and operation age on prognosis of infants with biliary atresia (BA) who received Kasai operation prior to 60 days of age.From 2004 to 2010, 158 infants received Kasai operation before turning 60 days old. According to Davenport 2012 classifications, 4 groups of BA were defined: cystic BA, syndrome BA, and associated malformation, cytomegalovirus (CMV)-associated BA, and isolated BA. Native (autologous) liver survival rates and incidence of cholangitis 2 years after operation, as well as jaundice clearance rates 3 months after operation, were recorded.Although infants who received the operation between 51 and 60 days of age had a better jaundice clearance 3 months after operation and lower incidence of cholangitis as compared with those under 40 or between 41 and 50 days of age, there was no significant difference in survival rates. Among types of BA, infants with cystic BA had the best prognosis. In the syndrome BA and associated malformations group, as well as CMV-associated group, infants who received the operation early (<40 days of age) had a worse outcome as compared with those who received the operation between 41 and 50 days or 51 and 60 days of age.Both clinical etiologic heterogeneity and operation age may influence BA prognosis.

Biliary atresia: From Australia to the zebrafish

This review is based upon an invited lecture for the 52nd Annual Meeting of the British Association of Paediatric Surgeons, July 2015. The aetiology of biliary atresia (BA) is at best obscure, but it is probable that a number of causes or pathophysiological mechanisms may be involved leading to the final common phenotype we recognise clinically. By way of illustration, similar conditions to human BA are described, including biliary agenesis, which is the normal state and peculiar final pattern of bile duct development in the jawless fish, the lamprey. Furthermore, there have been remarkable outbreaks in the Australian outback of BA in newborn lambs whose mothers were exposed to and grazed upon a particular plant species (Dysphania glomulifera) during gestation. More recent work using a zebrafish model has isolated a toxic isoflavonoid, now named Biliatresone, thought to be responsible for these outbreaks. Normal development of the bile ducts is reviewed and parallels drawn with two clinical variants thought to definitively have their origins in intrauterine life: Biliary Atresia Splenic Malformation syndrome (BASM) and Cystic Biliary Atresia (CBA). For both variants there is sufficient clinical evidence, including associated anomalies and antenatal detection, respectively, to warrant their aetiological attribution as developmental BA. CMV IgM +ve associated BA is a further variant that appears separate with distinct clinical, histological, and immunohistochemical features. In these it seems possible that this involves perinatal obliteration of a normally formed duct system. Although still circumstantial, this evidence appears convincing enough to perhaps warrant a different treatment strategy. This then still leaves the most common (more than 60% in Western series) variant, now termed Isolated BA, whereby origins can only be alluded to.

Brain abscess in hepatopulmonary syndrome associated with biliary atresia

The first-choice therapy for biliary atresia (BA) is Kasai hepatoportoenterostomy, which has been shown to greatly improve outcome. Various long-term complications, however, such as portal hypertension and hepatopulmonary syndrome (HPS), can occur in patients with native liver. A rare case of brain abscess in an 11-year-old girl with HPS associated with BA is reported. The patient underwent hepatoportoenterostomy for BA at 53 days of age, with resolution of hyperbilirubinemia. At 10 years of age, she was diagnosed with severe HPS with right-to-left shunting, and preparations for liver transplantation proceeded. Three months after the diagnosis, she had a right parietal brain abscess. Given that the brain abscess enlarged in size, surgical drainage of the brain abscess was performed. The postoperative course was uneventful, but a slight left hemiplegia remained at discharge. The presumed mechanism of abscess formation in HPS may be right-to-left bacterial transit through intrapulmonary vascular dilatations and/or arteriovenous fistulae.

Cytomegalovirus-associated biliary atresia: An aetiological and prognostic subgroup

BACKGROUND AND AIMS

Perinatal cytomegalovirus (CMV) infection is a possible cause or trigger of biliary atresia though clinical evidence is scant. We hypothesised that CMV IgM+ve biliary atresia is a separate clinical entity compared to CMV IgM-ve biliary atresia.

METHODS

Prospective single-centre study. 210 infants with histologically confirmed biliary atresia were treated in our institution (Jan. 2004 to Dec. 2011); of these 20 (9.5%) were CMV IgM+ve at presentation. We compared these with 111 infants who were CMV IgM-ve (controls) for clinical features, biochemistry at presentation and outcome following Kasai portoenterostomy (KPE). A blinded comparison of age-matched liver histology was also performed. Data are quoted as median (interquartile range). A P value ≤ 0.05 was regarded as significant.

RESULTS

Infants with CMV IgM+ve biliary atresia were older at Kasai portoenterostomy (or laparotomy) [70 (60-80) days vs. 56 (44-75)days; P = 0.003] and were more jaundiced [175 (147-224) vs. 140 (121-181) μmol/L; P = 0.002+ with higher AST*287 (157-403) vs. 180 (133-254) IU/L; P = 0.005] and aspartate aminotransferase-to-platelet ratio index [1.1 (0.79-3.0) vs. 0.63 (0.43-0.95)] levels. Liver histology: CMV IgM+ve biliary atresia was characterised by a greater degree of inflammation (P < 0.0001) and fibrosis (P = 0.02), whereas CMV IgM-ve isolated biliary atresia had a higher degree of lobular cholestasis (P = 0.001). This effect was independent of the effects of age at KPE.

OUTCOME

CMV IgM+ve biliary atresia had a poorer outcome with a reduced clearance of jaundice (15% vs. 52.2%; P = 0.002), native liver survival (P < 0.0001) and increased mortality (P = 0.002).

CONCLUSIONS

CMV IgM+ve biliary atresia is a distinct clinical and pathological entity with a diminished response to Kasai portoenterostomy.

Th-17 cells infiltrate the liver in human biliary atresia and are related to surgical outcome

BACKGROUND

Biliary atresia (BA), a cholangiopathy of unknown etiology is associated with intrahepatic mononuclear cell infiltrate. An abnormal reaction to viral exposure has been hypothesized in some cases. We aimed to investigate the nature of the CD4+ hepatic infiltrate in defined clinical variants of BA by quantification of inflammatory cell components.

METHODS

Liver biopsies of infants obtained at Kasai portoenterostomy (KPE) were stained immunohistochemically using monoclonal antibodies to Tbet, GATA-3, FOXP3 and interleukin (IL) 17, identifying Th-1, Th-2, Tregs and Th-17 cells respectively. T cells were counted with the aid of a graticule. Data are reported as median (range) of cells per high-power-field (×400) and compared using nonparametric statistical tests with P≤0.05 regarded as significant.

RESULTS

Liver biopsies from BA (n=37) and age-matched cholestatic controls (e.g. alpha-1-anti trypsin deficiency, Alagilles syndrome, n=12) were investigated. BA infants were divided into three groups: cytomegalovirus IgM +ve (CMV; n=9); BA splenic malformation (BASM; n=9) and isolated BA (IBA; n=19). All T-cell subsets were present in the portal tracts, with an overrepresentation of Th-1 (P<0.001) and Th-17 (P<0.03), but not Th-2 (P=0.94) or Tregs (P=0.15), compared to controls. Th-1 cells predominated in the CMV group; (18 [7-37] vs. 3 [0-14] [BASM] and vs. 5 [3-23] [IBA]; P<0.01 both), while no subgroup differences were seen for Th-17 cells. The degree of Th-1 cell infiltrate inversely correlated with platelet count (rS=-0.49; P<0.01). Th-17 cells were fewer (6 [2-11] vs. 11 [8-20]; P=0.02) in infants who cleared their jaundice (n=15, <20μmol/L) although this did not translate to improved native liver survival (P=0.17).

CONCLUSIONS

Th-17 cells infiltrate the liver in BA and are associated with a worse surgical outcome; a Th-1 profile predominates in CMV-associated BA.

Interleukin-8: A critical chemokine in biliary atresia

Biliary atresia (BA) is characterized by periductular inflammation and fibrosis and is associated with the progressive obliteration of the bile ducts. The induction and maintenance of systemic and local inflammatory responses plays a pivotal role in this process. Interleukin-8 (IL-8) is an important mediator of inflammation and the immune response in human disease. IL-8 is overexpressed in BA, and its expression positively correlates with inflammation and liver fibrosis. In this review, we focus on the available evidence, recent insights, and future clinical and preclinical possibilities regarding the role of IL-8 in BA.

Pathogenesis of biliary atresia: defining biology to understand clinical phenotypes

Biliary atresia is a severe cholangiopathy of early infancy that destroys extrahepatic bile ducts and disrupts bile flow. With a poorly defined disease pathogenesis, treatment consists of the surgical removal of duct remnants followed by hepatoportoenterostomy. Although this approach can improve the short-term outcome, the liver disease progresses to end-stage cirrhosis in most children. Further improvement in outcome will require a greater understanding of the mechanisms of biliary injury and fibrosis. Here, we review progress in the field, which has been fuelled by collaborative studies in larger patient cohorts and the development of cell culture and animal model systems to directly test hypotheses. Advances include the identification of phenotypic subgroups and stages of disease based on clinical, pathological and molecular features. Stronger evidence exists for viruses, toxins and gene sequence variations in the aetiology of biliary atresia, triggering a proinflammatory response that injures the duct epithelium and produces a rapidly progressive cholangiopathy. The immune response also activates the expression of type 2 cytokines that promote epithelial cell proliferation and extracellular matrix production by nonparenchymal cells. These advances provide insight into phenotype variability and might be relevant to the design of personalized trials to block progression of liver disease.

Low doses of CMV induce autoimmune-mediated and inflammatory responses in bile duct epithelia of regulatory T cell-depleted neonatal mice

Recent studies have indicated that perinatal infection with cytomegalovirus (CMV) may promote bile duct damage in biliary atresia (BA) and that the decreased regulatory T cell (Treg) percentage associated with BA may further amplify the bile duct damage. Although a majority of BA patients have had previous CMV infections and lower percentages of Tregs, it is unknown whether an initial exposure to a low dose of CMV could induce exaggerated and progressive biliary injury. A Treg-depleted neonatal mouse was infected with low-dose CMV (LD-CMV) as a model to study BA patients. LD-CMV infection in Treg-depleted mice induced extensive inflammation in both the intrahepatic and extrahepatic bile ducts, accompanied with injury to and atresia of intrahepatic bile ducts and partial obstruction of the extrahepatic bile ducts. Serum total and direct bilirubin amounts were also elevated. Evidence for the involvement of cellular and humoral autoimmune responses in LD-CMV-infection of Treg-depleted mice was also obtained through detection of increased percentages of CD3 and CD8 mononuclear cells and serum autoantibodies reactive to bile duct epithelial proteins, one of which was identified as α-enolase. Depletion of Tregs that can lead to the decreased inhibition of aberrantly activated hepatic T-lymphocytes and generation of autoantibodies may lead to further injury. Increased hepatic expression of Th1-related genes (TNF-α), IFN-γ-activated genes (STAT-1) and Th1 cytokines (TNF-α, lymphotactin, IL-12p40 and MIP -1γ) were also identified. In conclusion, autoimmune-mediated and inflammatory responses induced by LD-CMV infection in Treg-depleted mice results in increased intrahepatic and extrahepatic bile duct injury and contributed to disease progression.

α-SMA overexpression associated with increased liver fibrosis in infants with biliary atresia

OBJECTIVE

The mechanisms responsible for increased collagen production and hepatic fibrosis in biliary atresia (BA) remain largely unknown. We evaluated α-smooth muscle actin (α-SMA) expression in liver and the porta hepatis in infants with BA.

METHODS

Immunohistochemical staining for α-SMA and CD68 in the BA liver and porta hepatis was performed. A semiquantitative 3-grade staging system was employed to estimate liver fibrosis. The densities of CD68 in BA liver and the levels of direct bilirubin were assessed in relation to α-SMA expression.

RESULTS

α-SMA was found to be overexpressed in epithelial cells and in periductular collagen fibers. The expression in infants with BA was higher than that in the control group (P < 0.05). The amount of α-SMA in BA was positively correlated with liver fibrosis scores (r = 0.549, P = 0.022). The levels of α-SMA in the liver of BA were negatively related with improvements in direct bilirubin levels, 3 months postoperatively (r = -0.653, P = 0.029). The correlation between the α-SMA and CD-68 expression was not significantly different (r = 0.444, P = 0.057).

CONCLUSIONS

The expression of α-SMA in BA liver is higher than that in contro1 group. α-SMA expression is negatively correlated with the reduction of direct bilirubin, 3 months postoperatively, probably due to fibrosis or cirrhosis affecting the entire biliary system.

Interleukin-33 overexpression is associated with gamma-glutamyl transferase in biliary atresia

Interleukin-33 (IL-33) plays a crucial role in inflammation. However, it is not clear whether IL-33 levels are of clinical significance for patients with biliary atresia (BA). The purpose of this study was to determine correlations between serum IL-33 levels and the clinicopathologic features of BA. Serum samples were collected from 18 BA infants, 12 nonicteric choledochal cyst (CC) infants with normal liver function, and 10 healthy controls (HCs). Serum IL-33 levels were measured with an enzyme-linked immunosorbent assay (ELISA). Routine liver function tests were performed on the serum samples. qRT-PCR and Western blot analysis were used to detect IL-33 expression in BA liver biopsy tissues. Hepatic lobule localization of IL-33 expression in the hepatic lobule was conducted by immunohistochemistry (IHC). IL-33 levels in serum collected from BA infants were significantly elevated in comparison with CC and HC patients. Furthermore, the elevated serum levels of IL-33 in BA infants were correlated with gamma-glutamyl transferase (GGT) levels. The expression of IL-33 mRNA and protein levels were up-regulated in BA liver biopsy tissues in comparison with CC patients. IHC analysis revealed increased positive immunostaining for IL-33 in BA liver tissues as compared to that in CC tissues. These results suggest that IL-33 may play an important role in the pathogenesis of BA. In addition, the correlation of serum IL-33 levels with GGT levels may provide a novel marker for the diagnosis of BA.

Clues to the etiology of bile duct injury in biliary atresia

Biliary atresia (BA) is an infantile obstructive cholangiopathy of unknown etiology with suboptimal therapy, which is responsible for 40 to 50% of all pediatric liver transplants. Although the etiology of bile duct injury in BA in unknown, it is postulated that a pre- or perinatal viral infection initiates cholangiocyte apoptosis and release of antigens that trigger a Th1 immune response that leads to further bile duct injury, inflammation, and obstructive fibrosis. Humoral immunity and activation of the innate immune system may also play key roles in this process. Moreover, recent investigations from the murine BA model and human data suggest that regulatory T cells and genetic susceptibility factors may orchestrate autoimmune mechanisms. What controls the coordination of these events, why the disease only occurs in the first few months of life, and why a minority of infants with perinatal viral infections develop BA are remaining questions to be answered.

+276 G/T single nucleotide polymorphism of the adiponectin gene is associated with the susceptibility to biliary atresia

BACKGROUND

Biliary atresia (BA) is an intractable neonatal inflammatory and obliterative cholangiopathy, leading to progressive fibrosis and cirrhosis. Adiponectin, an anti-inflammatory adipokine, is known to play a possible role in liver diseases. The objective of our study was to determine the relationship between adiponectin gene polymorphisms and BA susceptibility.

METHODS

A total of 106 BA patients and 107 healthy controls were included in this study. Two single nucleotide polymorphisms (SNPs) of the adiponectin gene, +45T/G (rs2241766) and +276G/T (rs1501299), were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Genotype distributions of +45 T/G and +276 G/T SNPs were seen in the Hardy-Weinberg equilibrium for both BA patients and controls. The frequency of the G/G genotype at +276G/T was significantly higher in BA patients than in the controls (P=0.009). Regarding +45T/ G in BA patients, the frequency of the T/T genotype tended to be lower than in the controls, but the difference was not significant. Moreover, the G allele at +276G/T in BA patients was more common than in the controls (P=0.0043). In contrast, the frequency of the T allele at +45T/G was not significantly different between BA patients and the controls. None of the haplotypes studied was found to significantly influence the risk of BA.

CONCLUSIONS

+276G/T SNP is strongly associated with BA, particularly with the G allele. We postulate that the +276G/T adiponectin gene polymorphism confers increased susceptibility to BA.

Detection of hepatotropic viruses has no impact on the prognosis after Kasai procedure

BACKGROUND/PURPOSE

A viral origin of biliary atresia (BA) is discussed, and several studies have demonstrated different viral strains in liver biopsies of patients undergoing Kasai portoenterostomy. We hypothesized that the presence of hepatotropic viruses in patients undergoing portoenterostomy contributes to the progression of the disease and negatively affect the outcome.

METHODS

Liver biopsies were prospectively taken from 70 patients undergoing portoenterostomy in our department from April 1996 to April 2004. Samples were screened by polymerase chain reaction for all common hepatic viruses. Primary outcome parameter was survival with the native liver. Secondary parameters were postoperative serum activity of liver enzymes and serum bilirubin levels at different time points. Patients underwent regular follow-up until October 2008.

RESULTS

Twenty-eight patients (40%) were positive for 1 or more hepatotropic viruses. Four patients were lost to follow-up. In the remaining 66 patients, there was no significant difference in survival with their native liver between virus-positive and virus-negative patients. After a mean follow-up of 7.7 years (range, 4.6-16.1 years), 15 (23%) of 66 patients still lived with their native liver. There was no difference in liver enzymes, C-reactive protein, or bilirubin at any time point between both groups.

CONCLUSION

A significant number of our patients tested positive for hepatotropic viruses in liver biopsies at the time of the Kasai procedure, but the presence of virus had no influence on the course of BA. This suggests that the ongoing inflammatory process of BA leading to liver cirrhosis in most Kasai-treated patients is not affected by hepatotropic viruses. Our data question the necessity to aggressively screen for and treat viral infections in patients with BA.

Biliary atresia: cellular dynamics and immune dysregulation

The cause of biliary atresia is unknown; in the past few decades, the majority of investigations related to its pathogenesis have centered on viral infections and immunity. The acquired or perinatal form of biliary atresia entails a progressive inflammatory injury of bile ducts, leading to fibrosis and obliteration of both the extrahepatic and intrahepatic bile ducts. Theories of pathogenesis include viral infection, chronic inflammatory or autoimmune-mediated bile duct injury, and abnormalities in bile duct development. This review will focus solely on human studies pertaining to a potential viral trigger of bile duct injury at diagnosis and provide insight into the interplay of the innate and adaptive immune responses in the pathogenesis of disease.

Cytomegalovirus-specific T-cell reactivity in biliary atresia at the time of diagnosis is associated with deficits in regulatory T cells

Biliary atresia (BA) is a progressive, inflammatory cholangiopathy that culminates in fibrosis of extrahepatic and intrahepatic bile ducts. A leading theory on the pathogenesis of BA is that the bile duct damage is initiated by a virus infection, followed by a bile duct-targeted autoimmune response. One mechanism of autoimmunity entails a diminished number or function of regulatory T cells (Tregs). The aim of this study was to identify potential virus-specific liver T cells from infants with BA at the time of diagnosis, implicating the virus involved in early bile duct damage. A subaim was to determine if the presence of virus infection was associated with quantitative changes in Tregs. Liver T cells from BA and control patients were cultured with antigen-presenting cells in the presence of a variety of viral or control proteins. 56% of BA patients had significant increases in interferon-gamma-producing liver T cells in response to cytomegalovirus (CMV), compared with minimal BA responses to other viruses or the control group CMV response. In addition, a positive correlation between BA plasma CMV immunoglobulin M (IgM) and liver T-cell CMV reactivity was identified. Investigation of peripheral blood Tregs revealed significant deficits in Treg frequencies in BA compared with controls, with marked deficits in those BA patients who were positive for CMV.

CONCLUSION

Liver T-cell responses to CMV were identified in the majority of BA patients at diagnosis, suggesting perinatal CMV infection as a plausible initiator of bile duct damage. Deficiency of Tregs in BA implies decreased inhibition of inflammation and autoreactivity, potentially allowing for exaggerated bile duct injury.

Changes in epigenetic regulation of CD4+ T lymphocytesin biliary atresia

Biliary atresia (BA) is a virus-induced autoimmune disease associated with abnormal DNA methylation patterns that contribute to disease presentation. This study examined DNA methylation patterns, changes to genes associated with methylation regulation, and changes to the autoimmune-related gene interferon gamma (IFN-γ) in CD4+ T cells from BA patients. We demonstrated that genomic DNA isolated from CD4+ T cells harvested from infants presenting with BA were hypomethylated relative to healthy controls. In addition, DNA methyltransferase (DNMT1) and DNMT3a mRNA levels were significantly lower in BA CD4+ T cells compared with controls and methyl-DNA-binding domain proteins (MBD1) mRNA expression (but not MBD4 detected at higher levels in BA patients), which was significantly lower in CD4+ T cells from BA infants than in controls. DNMT1 expression positively correlated with global DNA methylation in BA CD4+ T cells. IFN-γ mRNA expression levels in BA patients were also significantly increased, and the IFN-γ gene promoter region was hypomethylated in BA CD4+ T cells compared with controls and negatively correlated with DNA methylation. These data suggest that methylation changes in CD4+ cells may contribute to BA disease presentation and progression by affecting the expression of genes associated with autoimmunity.

Development of a guinea pig model of perinatal cytomegalovirus-induced hepatobiliary injury

To explore the possible link between perinatal cytomegalovirus infection and onset of biliary atresia, we build up a perinatal cytomeglovirus induced hepatobiliary system injury model in guinea pigs, verified the biliary tropism of gpCMV and the related inflammatory injury. It suggested host immune status, local response to inflammation, and activation of Th1-cell-mediated antiviral immune responses contributed to newborn geinea pigs' hepatobiliary damage. The model was helpful in study the CMV infection and biliary injury.

Biliary atresia

Biliary atresia is a rare disease of infancy, which has changed within 30 years from being fatal to being a disorder for which effective palliative surgery or curative liver transplantation, or both, are available. Good outcomes for infants depend on early referral and timely Kasai portoenterostomy, and thus a high index of suspicion is needed for investigation of infants with persistent jaundice. In centres with much experience of treating this disorder, up to 60% of children will achieve biliary drainage after Kasai portoenterostomy and will have serum bilirubin within the normal range within 6 months. 80% of children who attain satisfactory biliary drainage will reach adolescence with a good quality of life without undergoing liver transplantation. Although much is known about management of biliary atresia, many aspects are poorly understood, including its pathogenesis. Several hypotheses exist, implicating genetic predisposition and dysregulation of immunity, but the cause is probably multifactorial, with obliterative extrahepatic cholangiopathy as the common endpoint. Researchers are focused on identification of relevant genetic and immune factors and understanding serum and hepatic factors that drive liver fibrosis after Kasai portoenterostomy. These factors might become therapeutic targets to halt the inevitable development of cirrhosis and need for liver transplantation.

Early cytomegalovirus infection and the long-term outcome of biliary atresia

AIM

To study the impact of ongoing cytomegalovirus (CMV) infection at presentation of biliary atresia (BA) on the long-term outcome after Kasai procedure.

METHODS

Twenty-eight patients with BA born 1988-1997 were included and followed-up until 2007. Eleven patients (group A) had ongoing CMV infection at presentation and were compared to the remaining 17 patients (group B). Median age at Kasai procedure was 75 days in group A and 70 days in group B (p = 0.12).

RESULTS

Including all patients, survival with native liver was 50% and 36% at 4 and 10 years of follow-up respectively. At the end of follow-up, it was 25% and overall survival was 68%. When comparing groups A and B, neither difference in survival with native liver (p = 0.67, log-rank test) nor in survival after liver transplantation was detected.

CONCLUSION

Survival with native liver after Kasai procedure is comparable to that of other centres. CMV positive patients may present with a later onset, alternatively the detection of CMV infection could delay the referral of BA patients. No significant differences in long-term outcome were detected with regard to early CMV infection.