Anatomical patterns of biliary atresia including hepatic radicles at the porta hepatis influence short- and long-term prognoses

Impact of gallbladder hypoplasia on hilar hepatic ducts in biliary atresia

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Biliary atresia: the development, pathological features, and classification of the bile duct

Biliary atresia is an occlusive biliary disease involving intrahepatic and extrahepatic bile ducts. Its etiology and pathogenesis are unclear. There are many manifestations of bile duct involvement in biliary atresia, but little is known about its occurrence and development. In addition, different classification methods have been proposed in different periods of biliary atresia, each with its advantages and disadvantages. The combined application of biliary atresia classification will help to improve the survival rate of patients with native liver. Therefore, this article reviews the development, pathological features, and classification of intrahepatic and extrahepatic bile ducts in biliary atresia, to provide a reference for the study of the pathogenesis and the choice of treatment methods.

Rare sequence variants associated with the risk of non-syndromic biliary atresia

AIM

The etiology of non-syndromic biliary atresia (BA) remains largely unknown. In this study, we performed genome-wide screening of genes associated with the risk of non-syndromic BA.

METHODS

We analyzed exome data of 15 Japanese patients with non-syndromic BA and 509 control individuals using an optimal sequence kernel association test (SKAT-O), a gene-based association study optimized for small-number subjects. Furthermore, we examined the frequencies of known BA-related single-nucleotide polymorphisms in the BA and control groups.

RESULTS

SKAT-O showed that rare damaging variants of MFHAS1, a ubiquitously expressed gene encoding a Toll-like receptor-associated protein, were more common in the BA group than in the control group (Bonferroni corrected p-value = 0.0097). Specifically, p.Val106Gly and p.Arg556Cys significantly accumulated in the patient group. These variants resided within functionally important domains. SKAT-O excluded the presence of other genes significantly associated with the disease risk. Of 60 known BA-associated single-nucleotide polymorphisms, only eight were identified in the BA group. In particular, p.Ile3421Met of MYO15A and p.Ala421Thr of THOC2 were more common in the BA group than in the control group. However, the significance of these two variants is questionable, because MYO15A has been linked to deafness, but not to BA, and the p.Ala421Thr of THOC2 represents a relatively common single-nucleotide polymorphism in Asia.

CONCLUSIONS

The results of this study indicate that rare damaging variants in MFHAS1 may constitute a risk factor for non-syndromic BA, whereas the contribution of other monogenic variants to the disease predisposition is limited.

Biliary Atresia in Adolescence and Adult Life: Medical, Surgical and Psychological Aspects

Prior to 1955, when Morio Kasai first performed the hepatic portoenterostomy procedure which now bears his name, Biliary atresia (BA) was a uniformly fatal disease. Both the Kasai procedure and liver transplantation have markedly improved the outlook for infants with this condition. Although long-term survival with native liver occurs in the minority, survival rates post liver transplantation are high. Most young people born with BA will now survive into adulthood but their ongoing requirements for health care will necessitate their transition from a family-centred paediatric service to a patient-centred adult service. Despite a rapid growth in transition services over recent years and progress in transitional care, transition from paediatric to adult services is still a risk for poor clinical and psychosocial outcomes and increased health care costs. Adult hepatologists should be aware of the clinical management and complications of biliary atresia and the long-term consequences of liver transplantation in childhood. Survivors of childhood illness require a different approach to that for young adults presenting after 18 years of age with careful consideration of their emotional, social, and sexual health. They need to understand the risks of non-adherence, both for clinic appointments and medication, as well as the implications for graft loss. Developing adequate transitional care for these young people is based on effective collaboration at the paediatric-adult interface and is a major challenge for paediatric and adult providers alike in the 21st century. This entails education for patients and adult physicians in order to familiarise them with the long-term complications, in particular for those surviving with their native liver and the timing of consideration of liver transplantation if required. This article focusses on the outcome for children with biliary atresia who survive into adolescence and adult life with considerations on their current management and prognosis.

The Outcome of Patients With Cystic Biliary Atresia With Intact Proximal Hepatic Ducts Following Hepatic-Cyst-Jejunostomy

OBJECTIVES

To determine the outcomes of patients with cystic biliary atresia by correlating the anatomy of the hepatic ducts with the choice of biliary reconstruction surgery.

BACKGROUND

The Kasai hepatoportoenterostomy (Kasai) is the initial surgical procedure offered to most patients with biliary atresia. In contrast, a hepatic-cyst-jejunostomy has been reported to be effective in patients with the cystic form of biliary atresia.

METHODS AND RESULTS

We performed an international multicenter retrospective review. Two hundred eighty-seven patients were included, and 33 cases of cystic biliary atresia were identified. Outcomes were the serum total bilirubin level 3 months post-surgery and native liver survival at 2 years of age and were compared between cases who received the Kasai versus hepatic-cyst-jejunostomy in correlation to the anatomy of proximal hepatic ducts. The patients were categorized into 3 anatomical groups: patent intact hepatic ducts (n = 10), patent hypoplastic hepatic ducts (n = 13), and obliterated hepatic ducts (n = 10). All 10 patients with patent intact hepatic duct group underwent hepatic-cyst-jejunostomy, and 9 experienced bile drainage and native liver survival. Among the 13 patients with hypoplastic hepatic ducts, 11 underwent the Kasai procedure, and 9 had bile drainage, whereas 2 underwent hepatic-cyst-jejunostomy, and one survived with the native liver. All of the patients with obliterated hepatic ducts underwent the Kasai procedure; 5 established biliary drainage and survived with the native liver. Of 5 who did not drain, 3 underwent liver transplantation.

CONCLUSIONS

In patients with cystic biliary atresia, the subset with a connection between cyst and intrahepatic bile ducts via intact proximal hepatic ducts had favorable clinical outcomes following hepatic-cyst-jejunostomy.

The favorable prognosis of cystic biliary atresia may be related to early surgery and mild liver pathological changes

OBJECTIVE

The objectives of this study is to compare the prognostic differences between cystic biliary atresia (CBA) and non-CBA, analyze the clinical and liver pathological differences between the two groups, and explore the possible factors that affect the native liver survival of infants with CBA after Kasai portoenterostomy (KPE).

METHODS

From 2013 to 2020, 131 infants with BA were admitted to Tianjin Children's Hospital. A total of 108 infants with BA were included after excluding those who did not undergo surgery after diagnosis (n = 23), including 12 cases of CBA and 96 cases of non-CBA. The clinical data, native liver survival and liver pathology, including liver fibrosis, bile ductular proliferation (BDP), bile plug, and portal area inflammation infiltration of the two study groups were compared.

RESULTS

CBA accounts for 9.16% (12/131) and type I CBA accounts for 6.87% (9/131) of all types of BA. 16.7% (2/12) of CBA were detected prenatally with diagnosis of choledochal cyst (CC). The age at KPE, total bilirubin, direct bilirubin, and total bile acid levels of CBA were significantly lower than those of non-CBA (P = 0.047, P = 0.013, P = 0.009, P = 0.010, respectively). The long and wide diameters of the gallbladder were significantly larger than those of non-CBA (both P < 0.001). The 1-, 3-, and 5-year survival rates of CBA were 83.3%, 71.4%, and 71.4%, respectively, and 56.5%, 32.5%, and 29.8%, respectively, in non-CBA. The difference between the two groups was statistically significant (P = 0.031). The degree of liver fibrosis and bile plug in non-CBA was higher than that of CBA (P = 0.004, P < 0.001, respectively). There was no difference of BDP and inflammation infiltration between the two groups (P = 0.285, P = 0.243, respectively).

CONCLUSION

CBA is a distinct type different from non-CBA, with different pathological processes, pathological manifestations, and clinical prognosis. The favorable prognosis of CBA may be derived from the early diagnosis, early operation, and mild pathological changes.