Microvascular proliferation of the portal vein branches in the liver of biliary atresia patients at Kasai operation is associated with a better long-term clinical outcome

Lymphangiogenesis in the liver of biliary atresia

BACKGROUND

Lymphatic vessels (LVs) play a crucial role in immune reactions by serving as the principal conduits for immune cells. However, to date, no study has analyzed the morphological changes in the LVs of patients with biliary atresia (BA). In this study, we aimed to determine the morphological changes in the LVs irrigating the liver in patients with BA, elucidate their correlations with the morphology of the portal vein (PV) branches, and discuss their etiopathogenetic significance.

METHODS

Morphometric analyses of liver biopsy specimens from patients treated between 1986 and 2016 were performed. The parameters measured were as follows: the whole liver area of the specimen, fibrotic area, number of LVs, LVs without patent lumen (designated as Ly0) and PV branches, and diameters of the LVs with patent lumen and the PVs.

RESULTS

The numbers of LVs, Ly0, and PV branches per unit area of the whole liver specimen were significantly higher in patients with BA than in control participants with liver disease and those with normal livers. However, no correlation was observed between the fibrotic area and the average diameter of LVs or PVs, and between the fibrotic area and the number of LVs or PV branches. Furthermore, no correlation was observed between the total number of LVs and the number of PV branches.

CONCLUSIONS

The present study showed a significant increase in the number of total LVs and Ly0, characterized by a high Ly0 to total LVs ratio, suggesting that lymphangiogenesis occurs in the liver of patients with BA.

Assessment of the utility of two-dimensional shear wave elastography and superb microvascular imaging in postoperative patients with biliary atresia

PURPOSE

We aimed to investigate whether prediction of liver fibrosis using two-dimensional shear wave elastography (2D-SWE) and vascular tree grading using superb microvascular imaging (SMI) are useful for postoperative follow-up in patients with biliary atresia (BA).

METHODS

We retrospectively collected data from medical records of 134 patients who underwent ultrasound examination with 2D-SWE or SMI, including 13 postoperative patients with BA and 121 non-BA patients. We investigated the distribution of liver stiffness values with SWE and vascular tree grading with SMI and evaluated correlations between these findings and biochemical indices of liver fibrosis in postoperative BA patients.

RESULTS

The SWE values of the BA group were not significantly different from that of any other disease groups in non-BA patients. In postoperative BA patients, SWE values correlated significantly with aspartate aminotransferase to platelet ratio index (Spearman rank correlation coefficient [rs] = 0.6380, p = 0.0256) and with the Fib-4 index (rs = 0.6526, p = 0.0214). SMI vascular tree grading of the BA group was significantly higher than that of the choledochal cyst group (p = 0.0008) and other hepatobiliary disorder group (p = 0.0030). In postoperative BA patients, SMI vascular tree grading was not positively correlated with any biochemical marker of fibrosis.

CONCLUSION

2D-SWE appears to be useful for follow-up in postoperative BA patients.

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.

Insight into microvascular adaptive alterations in the Glisson system of biliary atresia after Kasai portoenterostomy using X-ray phase-contrast CT

OBJECTIVES

To investigate microvascular alterations in the Glisson system of biliary atresia (BA) patients after Kasai portoenterostomy (KP) using three-dimensional (3D) virtual histopathology based on X-ray phase-contrast CT (PCCT).

METHODS

Liver explants from BA patients were imaged using PCCT, and 32 subjects were included and divided into two groups: KP (n = 16) and non-KP (n = 16). Combined with histological analysis and 3D visualization technology, 3D virtual histopathological assessment of the biliary, arterial, and portal venous systems was performed. According to loop volume ratio, 3D spatial density, relative surface area, tortuosity, and other parameters, pathological changes of microvasculature in the Glisson system were investigated.

RESULTS

In the non-KP group, bile ducts mostly manifested as radial multifurcated hyperplasia and twisted into loops. In the KP group, the bile duct hyperplasia was less, and the loop volume ratio of bile ducts decreased by 13.89%. Simultaneously, the arterial and portal venous systems presented adaptive alterations in response to degrees of bile duct hyperplasia. Compared with the non-KP group, the 3D spatial density of arteries in the KP group decreased by 3.53%, and the relative surface area decreased from 0.088 ± 0.035 to 0.039 ± 0.015 (p < .01). Deformed portal branches gradually recovered after KP, with a 2.93% increase in 3D spatial density and a decrease in tortuosity from 1.17 ± 0.06 to 1.14 ± 0.04 (p < .01) compared to the non-KP group.

CONCLUSION

3D virtual histopathology via PCCT clearly reveals the microvascular structures in the Glisson system of BA patients and provides key insights into the morphological mechanism of microvascular adaptation induced by biliary tract dredging after KP in BA disease.

KEY POINTS

• 3D virtual histopathology via X-ray phase-contrast computed tomography clearly presented the morphological structures and pathological changes of microvasculature in the Glisson system of biliary atresia patients. • The morphological alterations of microvasculature in the Glisson system followed the competitive occupancy mechanism in the process of biliary atresia.

New insights in understanding biliary atresia from the perspectives on maternal microchimerism

Biliary atresia (BA) is a fibroinflammatory cholangiopathy and portal venopathy. It is of unknown etiology and is associated with systemic immune dysregulation, in which the first insult begins before birth. Maternal microchimerism is a naturally occurring phenomenon during fetal life in which maternal alloantigens promote the development of tolerogenic fetal regulatory T-cells in utero. However, maternal cells may alter the fetus's response to self-antigens and trigger an autoimmune response under certain histocompatibility combinations between the mother and the fetus. A recent report on a set of dizygotic discordant twins with BA, one of whose placentae showed villitis of unknown etiology, implies a certain immune-mediated conflict between the fetus with BA and the mother. Maternal chimeric cells persist postnatally for various time spans and can cause cholangitis, which ultimately leads to liver failure. In contrast, patients who eliminate maternal chimeric cells may retain their liver function.

Insight into Bile Duct Reaction to Obstruction from a Three-dimensional Perspective Using ex Vivo Phase-Contrast CT

Background Biliary obstruction leads to an increase in biliary pressure within the biliary system, which induces the morphologic adaptation of the biliary tree. Purpose To observe and to quantify the morphologic characteristics of the adaptation in a bile duct ligation rat model and verify it in patients with biliary atresia in a three-dimensional (3D) manner using x-ray phase-contrast CT. Materials and Methods A bile duct ligation model was induced in 40 male Sprague-Dawley rats, which were divided into five groups: the control group (no ligation) and groups 2, 4, 6, and 8 weeks after bile duct ligation (eight animals in each group). Liver tissue samples (approximately 1.8 cm in length and 1.3 cm in height) were imaged by using phase-contrast CT and compared with histologic analysis. With a combination of phase-contrast CT and 3D visualization technology, the entire biliary system and the intrahepatic vascular system were quantitatively analyzed according to downstream, midstream, and upstream domains based on bile duct volume, surface area, and other parameters. Additionally, liver explant tissues from 28 patients with biliary atresia were studied to determine the impact of biliary tract reconstruction. Results To offset the increased biliary pressure within the biliary system, the ductular reaction in the downstream, midstream, and upstream domains manifested as dilatation, spiderweb-like looping, and interconnected honeycomb-like patterns, respectively. The most severe ductular reaction occurred in the upstream domain, and the relative surface area (mean, 0.02 μm^-1 ± 0.01, 0.04 μm^-1 ± 0.01, 0.07 μm^-1 ± 0.02, and 0.10 μm^-1 ± 0.02 for the 2-8-week groups, respectively; P < .01 among the groups) and volume fraction of ductules (mean, 16.54% ± 4.62, 19.69% ± 6.41, 26.92% ± 5.82, and 38.34% ± 10.36 for the 2-8-week groups, respectively; P < .01 among the groups except between the 2- and 4-week groups [P = .062]) significantly increased over time. In patients with biliary atresia, it was observed that both fibrosis and proliferative ductules regressed after successful biliary tract reconstruction following Kasai portoenterostomy. Furthermore, ductular reaction was accompanied by a progressive increase in the arterial supply but a loss of portal blood supply. Conclusion X-ray phase-contrast CT with three-dimensional rendering of the biliary system in a bile duct ligation rat model provides key insights into ductular reaction or biliary self-adaptation triggered by increased biliary pressure. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Vannier and Wang in this issue.

Anatomical and histological characteristics of the hepatobiliary system in adult Sox17 heterozygote mice

Biliary atresia (BA) is a rare neonatal disease characterized by inflammation and obstruction of the extrahepatic bile ducts (EHBDs). The Sox17-haploinsufficient (Sox17^+/- ) mouse is an animal model of BA that encompasses bile duct injury and subsequent BA-like inflammation by the neonatal stage. Most Sox17^+/- neonates die soon after birth, but some Sox17^+/- pups reach adulthood and have a normal life span, unlike human BA. However, the phenotype and BA-derived scars in the hepatobiliary organs of surviving Sox17^+/- mice are unknown. Here, we examined the phenotypes of the hepatobiliary organs in post-weaning and young adult Sox17^+/- mice. The results confirmed the significant reduction in liver weight, together with peripheral calcinosis and aberrant vasculature in the hepatic lobule, in surviving Sox17^+/- mice as compared with their wild-type (WT) littermates. Such hepatic phenotypes may be sequelae of hepatobiliary damage at the fetal and neonatal stages, a notion supported by the slight, but significant, increases in the levels of serum markers of liver damage in adult Sox17^+/- mice. The surviving Sox17^+/- mice had a shorter gallbladder in which ectopic hepatic ducts were more frequent compared to WT mice. Also, the surviving Sox17^+/- mice showed neither obstruction of the EHBDs nor atrophy or inflammation of hepatocytes or the intrahepatic ducts. These data suggest that some Sox17^+/- pups with BA naturally escape lethality and recover from fetal hepatobiliary damages during the perinatal period, highlighting the usefulness of the in vivo model in understanding the hepatobiliary healing processes after surgical restoration of bile flow in human BA.