Unique manifestations of biliary atresia provide new immunological insight into its etiopathogenesis

Biliary Atresia Animal Models: Is the Needle in a Haystack?

Biliary atresia (BA) is a progressive fibro-obliterative process with a variable degree of inflammation involving the hepatobiliary system. Its consequences are incalculable for the patients, the affected families, relatives, and the healthcare system. Scientific communities have identified a rate of about 1 case per 10,000-20,000 live births, but the percentage may be higher, considering the late diagnoses. The etiology is heterogeneous. BA, which is considered in half of the causes leading to orthotopic liver transplantation, occurs in primates and non-primates. To consolidate any model, (1) more transport and cell membrane studies are needed to identify the exact mechanism of noxa-related hepatotoxicity; (2) an online platform may be key to share data from pilot projects and new techniques; and (3) the introduction of differentially expressed genes may be useful in investigating the liver metabolism to target the most intricate bilio-toxic effects of pharmaceutical drugs and toxins. As a challenge, such methodologies are still limited to very few centers, making the identification of highly functional animal models like finding a "needle in a haystack". This review compiles models from the haystack and hopes that a combinatorial search will eventually be the root for a successful pathway.

Quantification of Maternal Microchimeric Cells in the Liver of Children With Biliary Atresia

ABSTRACT

Biliary atresia (BA) is a rare disorder of unknown etiology. There is a debate as to whether maternal microchimerism plays a significant role in the development of BA or in graft tolerance after liver transplantation. Here, we performed quantitative-PCR-based assays for liver tissues of children with BA and other diseases. Maternal cells were detected in 4/13 and 1/3 of the BA and control groups, respectively. The estimated number of maternal cells ranged between 0 and 34.7 per 106 total cells. The frequency and severity of maternal microchimerism were similar between the BA and control groups, and between patients with and without acute rejection of maternal grafts. These results highlight the high frequency of maternal microchimerism in the liver. This study provides no evidence for roles of microchimerism in the etiology of BA or in graft tolerance. Thus, the biological consequences of maternal microchimerism need to be clarified in future studies.

Role of long non-coding RNA-adducin 3 antisense RNA1 in liver fibrosis of biliary atresia

Biliary atresia (BA) is a devastating liver disease in neonates. Liver fibrosis is regarded as a universal and prominent feature of BA. Studies have revealed that long non-coding RNAs (lncRNAs) regulate cellular processes during the development of liver fibrosis in BA. Long non-coding RNA-adducin 3 antisense RNA1 (lnc-ADD3-AS1) has been shown to increase susceptibility to BA. However, the role of lnc-ADD3-AS1 in liver fibrosis in BA remains unclear. Here, we investigated the role of lnc-ADD3-AS1 in the proliferation, migration, and apoptosis of the immortalized human hepatic stellate cell (HSC) line, LX-2. We successfully overexpressed and silenced lnc-ADD3-AS1 in LX-2 cells using adenovirus vectors and evaluated the proliferation of transfected cells using the Cell Counting Kit-8 (CCK8) assay. Cell apoptosis was detected using annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double staining and flow cytometry. We then analyzed cell migration by performing wound-scratch and transwell migration assays. Our results show that lnc-ADD3-AS1 significantly promoted LX-2 cell proliferation and attenuated apoptosis. More importantly, lncRNA-ADD3-AS1 significantly accelerated the migration of LX-2 cells. Our data indicated that lncRNA-ADD3-AS1 plays a role in the pathogenesis of liver fibrosis in patients with BA and may serve as a potential diagnostic marker for monitoring liver fibrosis in BA or as a therapeutic target for the disease.

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.

Segmental Atrophy of Explanted Livers in Biliary Atresia: Pathological Data From 63 Cases of Failed Portoenterostomy

OBJECTIVES

Atrophy of the left lateral segment (LLS) is often encountered in liver transplantation (LT) for biliary atresia (BA). To clarify the meaning of the heterogeneous atrophy, we compared the pathological characteristics of the LLS with the right posterior segment (RPS) of BA livers obtained during LT.

METHODS

Among the 116 patients with BA who underwent LT at our hospital between 2014 and 2018, 63 patients with persistent cholestasis after the Kasai portoenterostomy (KP) were selected. Three pathologists evaluated tissues from the LLS and RPS for 5 pathological parameters. Positive areas in whole-slide image observed as portal inflammation, fibrosis, cholestasis, and ductular reaction, were analyzed with automated image quantitation. Moreover, we examined the relationship between the pathological score and the Pediatric End-stage Liver Disease (PELD) score.

RESULTS

The median age at LT was 7 months (range 4-26 months). Inflammation and fibrosis were significantly greater in the LLS than in the RPS (P < 0.001, for both); however, there were no differences in cholestasis, ductular reaction, and hepatocellular damage (P = 0.3, 0.3, and 0.82). The same results were obtained in automated image quantitation. Moreover, the sums of the 5 pathological scores in the LLS showed a significant positive correlation with the PELD score (P = 0.016, rs = 0.3).

CONCLUSIONS

More severe inflammation and fibrosis without cholestasis were observed in the LLS. The segmental atrophy may not be associated with poor bile drainage, but with etiopathogenesis of BA. Moreover, the proper site for biopsy during KP could be the LLS.

Severity of Ascites Is Associated with Increased Mortality in Patients with Cirrhosis Secondary to Biliary Atresia

BACKGROUND

Very few prior studies have investigated the presence of ascites as a prognostic factor in children with cirrhosis. To the best of our knowledge, there are no prior studies evaluating the relationship between severity of ascites and patient survival in children with biliary atresia and cirrhosis.

AIMS

To evaluate the association between severity of ascites and survival of children with cirrhosis and biliary atresia.

METHODS

All children with cirrhosis secondary to biliary atresia evaluated at our institution from 2000 to 2014 were included in this study. Patients were classified into four groups: NA = no ascites; A1 = grade 1 ascites; A2 = grade 2 ascites; and A3 = grade 3 ascites. The primary endpoint of the study was mortality within the first year after patient inclusion. Ninety-day mortality was also evaluated. Prognostic factors related to both endpoints also were studied.

RESULTS

One-year patient survival for NA was 97.1%, versus 80.8% for A1, versus 52% for A2, versus 13.6 for A3 (p < 0.001). The presence of ascites increased mortality by 17 times. In the multivariate analysis, clinically detectable ascites (HR 3.14, 95% CI 1.14-8.60, p = 0.026), lower sodium (HR 1.15, 95% CI 1.04-1.27, p = 0.006), higher bilirubin (HR 1.06, 95% CI 1.00-1.12, p = 0.023), and higher PELD score (HR 1.05, 95% CI 1.02-1.08, p = 0.001) were all associated with decreased survival. Lower serum sodium (HR 1.20, 95% CI 1.09-1.32, p < 0.001) and higher PELD score (HR 1.03, 95% CI 1.001-1.063, p = 0.043) were associated with increased 90-day mortality.

CONCLUSIONS

Clinically detectable ascites is associated with decreased 1-year survival of children with biliary atresia. These patients should be treated with caution and prioritized for liver transplantation.

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

AIM OF THE STUDY

We previously showed an increased number of smaller portal vein (PV) branches in the portal areas of liver biopsy specimens of biliary atresia (BA) patients. We evaluated the correlation between this histopathological feature and the prognosis.

PATIENTS AND METHODS

Twenty-five consecutive patients with BA encountered between 2000 and 2012 were classified into three prognostic groups based on their postoperative outcomes: Excellent (n = 11) for native-liver survivors with a normal liver function, Good (n = 6) for native-liver survivors with liver dysfunction, and Poor (n = 8) for survivors after liver transplant or on a waiting list. Data from morphometrical analyses, including the fibrotic portal area, numbers of PVs, diameter and total area of PV branches, were statistically compared among the three groups.

MAIN RESULTS

The number of PV branches per unit area of the whole-liver specimen in the poor prognostic group was significantly lower than that in the excellent group (3.1 ± 0.6 vs. 5.2 ± 2.0/mm², p = 0.03). There were no significant differences in the other parameters.

CONCLUSIONS

This is the first report on the relationships between morphometrically analyzed PV branches and the postoperative course in BA patients. The portal venous system is involved as the primary lesion in BA.

Long Noncoding RNA H19 Contributes to Cholangiocyte Proliferation and Cholestatic Liver Fibrosis in Biliary Atresia

Biliary atresia (BA) is a neonatal liver disease featuring cholestasis and severe liver fibrosis (LF). Despite advances in the development of surgical treatment, lacking an early diagnostic marker and intervention of LF invariably leads to death from end-stage liver disease in the early years of life. We previously reported that knockout of sphingosine 1-phosphate receptor 2 (S1PR2) protected mice from bile duct ligation (BDL)-induced cholangiocyte proliferation and LF. Our recent studies further showed that both hepatic and serum exosomal long noncoding RNA H19 (lncRNAH19) levels are correlated with cholestatic injury in multidrug resistance 2 knockout (Mdr2^-/- ) mice. However, the role of lncRNAH19 in BA progression remains unclear. Here, we show that both hepatic and serum exosomal H19 levels are positively correlated with severity of fibrotic liver injuries in BA patients. H19 deficiency protects mice from BDL-induced cholangiocyte proliferation and LF by inhibiting bile-acid-induced expression and activation of S1PR2 and sphingosine kinase 2 (SphK2). Furthermore, H19 acts as a molecular sponge for members of the microRNA let-7 family, which results in up-regulation of high-mobility group AT-hook 2 (HMGA2), a known target of let-7 and enhancement of biliary proliferation. Conclusion: These results indicate that H19 plays a critical role in cholangiocyte proliferation and cholestatic liver injury in BA by regulating the S1PR2/SphK2 and let-7/HMGA2 axis. Serum exosomal H19 may represent a noninvasive diagnostic biomarker and potential therapeutic target for BA.

Morphometric demonstration of portal vein stenosis and hepatic arterial medial hypertrophy in patients with biliary atresia

PURPOSE

Portal hypertension in patients with biliary atresia (BA) is generally thought to result from portal vein (PV) narrowing secondary to hepatic fibrosis. To test the hypothesis, we morphometrically analyzed the PVs and hepatic arteries (HAs).

METHODS

Morphometrical analyses of 25 BA and 26 non-BA liver biopsy specimens from patients treated from 2000 to 2014. The total specimen area, the fibrotic portal area, vessel diameter and medial thickness of the HAs were measured.

RESULTS

The PV diameter in BA patients was significantly smaller than that in non-BA patients. In BA, the numbers of normal-sized PVs and capillaries were decreased and increased, respectively. The PV diameter was not significantly correlated with the degree of fibrosis. We newly found that medial hypertrophy and the HA diameter increased with the number of endothelial cells in BA. The PV diameter was not significantly correlated with the medial thickness and was positively correlated with the HA diameter in BA.

CONCLUSIONS

The narrowing of the PV is unlikely to occur secondarily to liver fibrosis. The medial hypertrophy of the HA is not correlated with the decrease in the PV blood flow. These findings seem to be unique to the primary vascular lesions of BA.

Biliary atresia combined with progressive familial intrahepatic cholestasis type 3: A case report and review of the literature

RATIONALE

Neonatal cholestasis is one of the most serious diseases in infancy. Progressive familial intrahepatic cholestasis (PFIC) is a disease that leads to intrahepatic cholestasis. It is one of the common causes of neonatal cholestasis in addition to biliary atresia (BA). The differential diagnosis of neonatal cholestasis is clinically challenging for pediatricians.

PATIENT CONCERNS

A 4-month-old female presented with severe jaundice, pruritus, and pale stool for 20 days. Abnormally strong echoes near the portal area, an abnormally small gallbladder with an irregularly stiff wall, and splenomegaly were identified on abdominal ultrasound. Blood tests showed elevated alanine aminotransferase, total bilirubin, conjugated bilirubin, gamma-glutamyltranspeptidase, and total bile acid levels.

DIAGNOSIS

Intraoperative cholangiography showed BA. ABCB4 gene mutation IVS13+6G>A/G was confirmed by genetic testing. The patient was diagnosed with BA combined with PFIC3.

INTERVENTIONS

Kasai portoenterostomy and ursodeoxycholic acid were used for treatment.

OUTCOMES

Her clinical symptoms and blood tests improved gradually. No recurrence was noted during 1 year of follow-up.

LESSONS

Additional examinations, such as genetic testing, should be considered in patients with BA who had refractory jaundice after Kasai portoenterostomy in order to exclude intrahepatic cholestasis.

Immune Status in Children Before Liver Transplantation-A Cross-Sectional Analysis Within the ChilsSFree Multicentre Cohort Study

Background: Both, markers of cellular immunity and serum cytokines have been proposed as potential biomarkers for graft rejection after liver transplantation. However, no good prognostic model is available for the prediction of acute cellular rejection. The impact of underlying disease and demographic factors on immune status before pediatric liver transplantation (pLTx) is still poorly understood. We investigated expression of immune markers before pLTx, in order to better understand the pre-transplant immune status. Improved knowledge of the impact of pre-transplant variables may enhance our understanding of immunological changes post pLTx in the future.

Methods: This is a cross-sectional analysis of data from the ChilSFree study, a European multicentre cohort study investigating the longitudinal patterns of immune response before and after pLTx. Immune cell counts and soluble immune markers were measured in 155 children 1–30 days before pLTx by TruCount analysis and BioPlex assays. Results were logarithmised due to skewed distributions and then compared according to age, sex, and diagnosis using t-tests, ANOVAs, and Tukey post-hoc tests. The association between immune markers at time of pLTx and patients' age was assessed using a fractional polynomial approach. Multivariable regression models were used to assess the relative contribution of each factor.

Results: Sex had no effect on immune status. We found strong evidence for age-specific differences in the immune status. The majority of immune markers decreased in a log-linear way with increasing age. T and B cells showed a sharp increase within the first months of life followed by a log-linear decline in older age groups. Several immune markers were strongly associated with underlying diagnoses. The effects of age and underlying disease remained virtually unchanged when adjusting for each other in multivariable models.

Discussion: We show for the first time that age and diagnosis are major independent determinants of cellular and soluble immune marker levels in children with end-stage liver disease. These results need to be considered for future research on predictive immune monitoring after pLTx.

Transient c-Src Suppression During Endodermal Commitment of Human Induced Pluripotent Stem Cells Results in Abnormal Profibrotic Cholangiocyte-Like Cells

Directed differentiation of human induced pluripotent stem cells (iPSCs) toward hepatobiliary lineages has been increasingly used as models of human liver development/diseases. As protein kinases are important components of signaling pathways regulating cell fate changes, we sought to define the key molecular mediators regulating human liver development using inhibitors targeting tyrosine kinases during hepatic differentiation of human iPSCs. A library of tyrosine kinase inhibitors was used for initial screening during the multistage differentiation of human iPSCs to hepatic lineage. Among the 80 kinase inhibitors tested, only Src inhibitors suppressed endoderm formation while none had significant effect on later stages of hepatic differentiation. Transient inhibition of c-Src during endodermal induction of human iPSCs reduced endodermal commitment and expression of endodermal markers, including SOX17 and FOXA2, in a dose-dependent manner. Interestingly, the transiently treated cells later developed into profibrogenic cholangiocyte-like cells expressing both cholangiocyte markers, such as CK7 and CK19, and fibrosis markers, including Collagen1 and smooth muscle actin. Further analysis of these cells revealed colocalized expression of collagen and yes-associated protein (YAP; a marker associated with bile duct proliferation/fibrosis) and an increased production of interleukin-6 and tumor necrosis factor-α. Moreover, treatment with verteporfin, a YAP inhibitor, significantly reduced expression of fibrosis markers. In summary, these results suggest that c-Src has a critical role in cell fate determination during endodermal commitment of human iPSCs, and its alteration in early liver development in human may lead to increased production of abnormal YAP expressing profibrogenic proinflammatory cholangiocytes, similar to those seen in livers of patients with biliary fibrosis. Stem Cells 2019;37:306-317.

Rethinking de novo immune hepatitis, an old concept for liver allograft rejection: Relevance of glutathione S-transferase T1 mismatch

Antibody-mediated rejection (AMR) in liver transplantation has long been underestimated. The concept of the liver as an organ susceptible to AMR has emerged in recent years, not only in the context of the major histocompatibility complex with the presence of HLA donor-specific antibodies, but also with antigens regarded as “minor”, whose role in AMR has been demonstrated. Among them, antibodies against glutathione S-transferase T1 have been found in 100% of patients with de novo autoimmune hepatitis (dnAIH) when studied. In its latest update, the Banff Working Group for liver allograft pathology proposed replacing the term dnAIH with plasma cell (PC)-rich rejection. Antibodies to glutathione S-transferase T1 (GSTT1) in null recipients of GSTT1 positive donors have been included as a contributory but nonessential feature of the diagnosis of PC-rich rejection. Also in this update, non-organ-specific anti-nuclear or smooth muscle autoantibodies are no longer included as diagnostic criteria. Although initially found in a proportion of patients with PC-rich rejection, the presence of autoantibodies is misleading since they are not disease-specific and appear in many different contexts as bystanders. The cellular types and proportions of the inflammatory infiltrates in diagnostic biopsies have been studied in detail very recently. PC-rich rejection biopsies present a characteristic cellular profile with a predominance of T lymphocytes and a high proportion of PCs, close to 30%, of which 16.48% are IgG4⁺. New data on the relevance of GSTT1-specific T lymphocytes to PC-rich rejection will be discussed in this review.

Ethnic variation in the incidence of biliary atresia correlates with the frequency of the most prevalent haplotype in its population

The cause of biliary atresia (BA) remains an enigma. However, an ethnic diversity in the incidence of BA is so unique that anthropological approach may provide some etiopathogenetic implications in the disease mechanism. We previously reported that an association of maternal microchimerism (MMc) in BA and a significant compatibility of HLA-A between the patient with BA and their mother. Across the 10 countries (Japan, South Korea, Taiwan, Philippines, New Zealand (Maori population), UK, France, Germany, Norway, and Sweden), we determined the frequency of the most prevalent HLA haplotypes of each country from Allele Frequency Database and found that it was significantly correlated with the incidence of BA of the respective country (p = 0.0126). This observation better fits the MMc theory as an etiopathogenesis, that is, maternal effector cells are likely to migrate into the fetus in a relatively homogenous population and may damage the developing bile duct structure and portal vein endothelium, depending on materno-fetal tolerance and immunity.