Biliary atresia is associated with CD4+ Th1 cell-mediated portal tract inflammation

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.

LRH-1 agonist DLPC through STAT6 promotes macrophage polarization and prevents parenteral nutrition-associated cholestasis in mice

BACKGROUND AND AIMS

Parenteral nutrition-associated cholestasis (PNAC) is an important complication in patients with intestinal failure with reduced LRH-1 expression. Here, we hypothesized that LRH-1 activation by its agonist, dilauroylphosphatidylcholine (DLPC), would trigger signal transducer and activator of transcription 6 (STAT6) signaling and hepatic macrophage polarization that would mediate hepatic protection in PNAC.

APPROACH AND RESULTS

PNAC mouse model (oral DSSx4d followed by PNx14d; DSS-PN) was treated with LRH-1 agonist DLPC (30 mg/kg/day) intravenously. DLPC treatment prevented liver injury and cholestasis while inducing hepatic mRNA expression of Nr5a2 (nuclear receptor subfamily 5 group A member 2), Abcb11 (ATP binding cassette subfamily B member 11), Abcg5 (ATP-binding cassette [ABC] transporters subfamily G member 5), Abcg8 (ATP-binding cassette [ABC] transporters subfamily G member 8), nuclear receptor subfamily 0, and ATP-binding cassette subfamily C member 2 ( Abcc2) mRNA, all of which were reduced in PNAC mice. To determine the mechanism of the DLPC effect, we performed RNA-sequencing analysis of the liver from Chow, DSS-PN, and DSS-PN/DLPC mice, which revealed DLPC upregulation of the anti-inflammatory STAT6 pathway. In intrahepatic mononuclear cells or bone-marrow derived macrophages (BMDM) from PNAC mice, DLPC treatment prevented upregulation of pro-inflammatory (M1) genes, suppressed activation of NFκB and induced phosphorylation of STAT6 and its target genes, indicating M2 macrophage polarization. In vitro, incubation of DLPC with cultured macrophages showed that the increased Il-1b and Tnf induced by exposure to lipopolysaccharides or phytosterols was reduced significantly, which was associated with increased STAT6 binding to promoters of its target genes. Suppression of STAT6 expression by siRNA in THP-1 cells exposed to lipopolysaccharides, phytosterols, or both resulted in enhanced elevation of IL-1B mRNA expression. Furthermore, the protective effect of DLPC in THP-1 cells was abrogated by STAT6 siRNA.

CONCLUSIONS

These results indicate that activation of LRH-1 by DLPC may protect from PNAC liver injury through STAT6-mediated macrophage polarization.

Technical optimization of spatially resolved single-cell transcriptomic datasets to study clinical liver disease

Single cell and spatially resolved 'omic' techniques have enabled deep characterization of clinical pathologies that remain poorly understood, providing unprecedented insights into molecular mechanisms of disease. However, transcriptomic platforms are costly, limiting sample size, which increases the possibility of pre-analytical variables such as tissue processing and storage procedures impacting RNA quality and downstream analyses. Furthermore, spatial transcriptomics have not yet reached single cell resolution, leading to the development of multiple deconvolution methods to predict individual cell types within each transcriptome 'spot' on tissue sections. In this study, we performed spatial transcriptomics and single nucleus RNA sequencing (snRNAseq) on matched specimens from patients with either histologically normal or advanced fibrosis to establish important aspects of tissue handling, data processing, and downstream analyses of biobanked liver samples. We observed that tissue preservation technique impacts transcriptomic data, especially in fibrotic liver. Single cell mapping of the spatial transcriptome using paired snRNAseq data generated a spatially resolved, single cell dataset with 24 unique liver cell phenotypes. We determined that cell-cell interactions predicted using ligand-receptor analysis of snRNAseq data poorly correlated with cellular relationships identified using spatial transcriptomics. Our study provides a framework for generating spatially resolved, single cell datasets to study gene expression and cell-cell interactions in biobanked clinical samples with advanced liver disease.

Immune-mediated cholangiopathies in children: the need to better understand the pathophysiology for finding the future possible treatment targets

Cholangiopathies are defined as focal or extensive damage of the bile ducts. According to the pathogenetic mechanism, it may be immune-mediated or due to genetic, infectious, toxic, vascular, and obstructive causes. Their chronic evolution is characterized by inflammation, obstruction of bile flow, cholangiocyte proliferation, and progression toward fibrosis and cirrhosis. Immune-mediated cholangiopathies comprise primary sclerosing cholangitis (PSC), autoimmune cholangitis and IgG4-associated cholangitis in adults and biliary atresia (BA), neonatal sclerosing cholangitis (NSC) in children. The main purpose of this narrative review was to highlight the similarities and differences among immune-mediated cholangiopathies, especially those frequent in children in which cholangiocyte senescence plays a key role (BA, NSC, and PSC). These three entities have many similarities in terms of clinical and histopathological manifestations, and the distinction between them can be hard to achieve. In BA, bile duct destruction occurs due to aggression of the biliary cells due to viral infections or toxins during the intrauterine period or immediately after birth. The consequence is the activation of the immune system leading to severe inflammation and fibrosis of the extrahepatic biliary tract, lumen stenosis, and impairment of the biliary flow. PSC is characterized by inflammation and fibrosis of intra- and extrahepatic bile ducts, leading to secondary biliary cirrhosis. It is a multifactorial disease that occurs because of genetic predisposition [human leukocyte antigen (HLA) and non-HLA haplotypes], autoimmunity (cellular immune response, autoantibodies, association with inflammatory bowel disease), environmental factors (infections or toxic bile), and host factors (intestinal microbiota). NSC seems to be a distinct subgroup of childhood PSC that appears due to the interaction between genetic predisposition (HLA B8 and DR3) and the disruption of the immune system, validated by elevated IgG levels or specific antibodies [antinuclear antibody (ANA), anti-smooth muscle antibody (ASMA)]. Currently, the exact mechanism of immune cholangiopathy is not fully understood, and further data are required to identify individuals at high risk of developing these conditions. A better understanding of the immune mechanisms and pathophysiology of BA, NSC, and PSC will open new perspectives for future treatments and better methods of preventing severe evolution.

Plasticity between type 2 innate lymphoid cell subsets and amphiregulin expression regulates epithelial repair in biliary atresia

BACKGROUND AND AIMS

Although a dysregulated type 1 immune response is integral to the pathogenesis of biliary atresia, studies in both humans and mice have uncovered a type 2 response, primarily driven by type 2 innate lymphoid cells. In nonhepatic tissues, natural type 2 innate lymphoid cell (nILC2s) regulate epithelial proliferation and tissue repair, whereas inflammatory ILC2s (iIlC2s) drive tissue inflammation and injury. The aim of this study is to determine the mechanisms used by type 2 innate lymphoid cell (ILC2) subpopulations to regulate biliary epithelial response to an injury.

APPROACH AND RESULTS

Using Spearman correlation analysis, nILC2 transcripts, but not those of iILC2s, are positively associated with cholangiocyte abundance in biliary atresia patients at the time of diagnosis. nILC2s are identified in the mouse liver through flow cytometry. They undergo expansion and increase amphiregulin production after IL-33 administration. This drives epithelial proliferation dependent on the IL-13/IL-4Rα/STAT6 pathway as determined by decreased nILC2s and reduced epithelial proliferation in knockout strains. The addition of IL-2 promotes inter-lineage plasticity towards a nILC2 phenotype. In experimental biliary atresia induced by rotavirus, this pathway promotes epithelial repair and tissue regeneration. The genetic loss or molecular inhibition of any part of this circuit switches nILC2s to inflammatory type 2 innate lymphoid cell-like, resulting in decreased amphiregulin production, decreased epithelial proliferation, and the full phenotype of experimental biliary atresia.

CONCLUSIONS

These findings identify a key function of the IL-13/IL-4Rα/STAT6 pathway in ILC2 plasticity and an alternate circuit driven by IL-2 to promote nILC2 stability and amphiregulin expression. This pathway induces epithelial homeostasis and repair in experimental biliary atresia.

Technical optimization of spatially resolved single-cell transcriptomic datasets to study clinical liver disease

Single cell and spatially resolved 'omic' techniques have enabled deep characterization of clinical pathologies that remain poorly understood, providing unprecedented insights into molecular mechanisms of disease. However, transcriptomic platforms are costly, limiting sample size, which increases the possibility of pre-analytical variables such as tissue processing and storage procedures impacting RNA quality and downstream analyses. Furthermore, spatial transcriptomics have not yet reached single cell resolution, leading to the development of multiple deconvolution methods to predict individual cell types within each transcriptome 'spot' on tissue sections. In this study, we performed spatial transcriptomics and single nucleus RNA sequencing (snRNASeq) on matched specimens from patients with either histologically normal or advanced fibrosis to establish important aspects of tissue handling, data processing, and downstream analyses of biobanked liver samples. We observed that tissue preservation technique impacts transcriptomic data, especially in fibrotic liver. Deconvolution of the spatial transcriptome using paired snRNASeq data generated a spatially resolved, single cell dataset with 24 unique liver cell phenotypes. We determined that cell-cell interactions predicted using ligand-receptor analysis of snRNASeq data poorly correlated with celullar relationships identified using spatial transcriptomics. Our study provides a framework for generating spatially resolved, single cell datasets to study gene expression and cell-cell interactions in biobanked clinical samples with advanced liver disease.

Exome-wide assessment of isolated biliary atresia: A report from the National Birth Defects Prevention Study using child-parent trios and a case-control design to identify novel rare variants

The etiology of biliary atresia (BA) is unknown, but recent studies suggest a role for rare protein-altering variants (PAVs). Exome sequencing data from the National Birth Defects Prevention Study on 54 child-parent trios, one child-mother duo, and 1513 parents of children with other birth defects were analyzed. Most (91%) cases were isolated BA. We performed (1) a trio-based analysis to identify rare de novo, homozygous, and compound heterozygous PAVs and (2) a case-control analysis using a sequence kernel-based association test to identify genes enriched with rare PAVs. While we replicated previous findings on PKD1L1, our results do not suggest that recurrent de novo PAVs play important roles in BA susceptibility. In fact, our finding in NOTCH2, a disease gene associated with Alagille syndrome, highlights the difficulty in BA diagnosis. Notably, IFRD2 has been implicated in other gastrointestinal conditions and warrants additional study. Overall, our findings strengthen the hypothesis that the etiology of BA is complex.

Development of liver inflammatory injury in biliary atresia: from basic to clinical research

Biliary atresia (BA) is a severe cholangiopathy in infants. It is characterized by inflammatory fibro-obliteration of the intra- and extrahepatic bile ducts. Although the restoration of bile flow can be successful after Kasai operation, the rapid progression of liver fibrosis can continue, leading to cirrhosis. It is believed that the progression of liver fibrosis in BA is exacerbated by complicated mechanisms other than the consequence of bile duct obstruction. The fibrogenic cascade in BA liver can be divided into three stages, including liver inflammatory injury, myofibroblast activation, and fibrous scar formation. Recent studies have revealed that the activation of an immune response following bile duct injury plays an important role in promoting the inflammatory process, the releasing of inflammatory cytokines, and the development of fibrogenesis in BA liver. In this article, we summarized the evidence regarding liver inflammatory injury and the possible mechanisms that explain the rapid progression of liver fibrosis in BA.

IL13 and periostin in active fibrogenic areas of the extrahepatic bile ducts in biliary atresia patients

BACKGROUND

The leading pathology of biliary atresia (BA) is inflammatory and fibrous obstruction of extrahepatic bile duct, but the pathogenesis remains unclear. IL13 is a cytokine associated with allergies and inflammatory fibrosis, and periostin induces fibrogenesis by stimulation with IL13. We analyzed the involvement of IL13 and periostin in inflammatory fibrosis in the extrahepatic bile duct of BA patients.

MATERIALS AND METHODS

Surgically resected tissues from the hepatic hilar area of BA patients were immunostained with CD45, α-SMA, IL13 and periostin and statistically analyzed. Fibroblasts from the resected tissue were cultured with recombinant IL13, and periostin production was analyzed by quantitative polymerase chain reaction and Western blotting.

RESULTS

IL13 was stained in 93% of large and micro bile ducts, and 92.1% matched with the CD45 location (p = 0.006) around the large bile ducts. Periostin staining correlated with the localization of IL13 and αSMA (p < 0.001) around the large bile ducts. Periostin mRNA and protein were upregulated by IL13 stimulation in cultured fibroblasts.

CONCLUSION

IL13 was associated with induced periostin expression by fibroblasts, playing a vital role in the pathogenesis of fibrogenesis around the extrahepatic bile duct in BA.

Diagnostic Performance of PD-L1 versus PD-1 Expression in Circulating CD20 Cells in Diffuse Large B-Cell Lymphoma

This study aimed to investigate PD-L1 and PD-1 expression in circulating CD20+ cells in diffuse larger B-cell lymphoma (DLBCL) and to evaluate the predictive and diagnostic performance of PD-L1 versus PD-1 expression in circulating CD20+ cells in DLBCL. Percentages of CD20+, PD-L1+CD20+, and PD-1+CD20+ cells were measured by flow cytometry in 40 DLBCL blood samples and 19 healthy controls. The DLBCL patient group was subdivided into 20 newly diagnosed patients with no treatment yet and 20 patients that had finished six cycles of CHOP therapy. Percentages of PD-L1+CD20+ and PD-1+CD20+ cells were highly significantly increased in pre-therapy patients in comparison to healthy volunteers (p < 0.001). Meanwhile, a significant decrease in percentages of PD-L1+CD20+ and PD-1+CD20+ was observed in post-CHOP therapy patients in comparison to pre-therapy patients (p < 0.001). PD-L1+CD20+ cells were significantly decreased in post-therapy patients when compared to normal controls (p < 0.001), while not for PD-1+CD20+ cells. A strong significant positive correlation between percentages of PD-L1+CD20+ and PD-1+CD20+ was detected in DLBCL patients (p < 0.001). In the pre-therapy group, high PD-L1+CD20+ and PD-1+CD20+ percentages were correlated with serum LDH levels (p = 0.021, p < 0.001). High percentages of PD-1+CD20+ were found in DLBCL patients with splenomegaly (p = 0.027). The results revealed that patients with advanced tumor stages, poor ECOG performance, and non-GCB DLBCL type had increased percentages of PD-L1+CD20+ and PD-1+CD20+ cells. Moreover, PD-L1+CD20+ % and PD-1+CD20+ % were significantly increased in DLBCL patients with bone marrow involvement or B symptoms. The superiority of PD-L1+CD20+ over PD-1+CD20+ was more profound in DLBCL prediction [AUC: 1.0] and in discriminating newly diagnosed patients [AUC: 1.0]. The findings suggest that increased PD-L1/PD-1 expression in peripheral CD20 cells may serve as a companion diagnostic marker for DLBCL. Moreover, percentages of PD-L1+CD20+ cells have better diagnostic performance with higher sensitivity and specificity than PD-1+CD20+ %.

The neonatal liver: Normal development and response to injury and disease

The liver emerges from the ventral foregut endoderm around 3 weeks in human and 1 week in mice after fertilization. The fetal liver works as a hematopoietic organ and then develops functions required for performing various metabolic reactions in late fetal and neonatal periods. In parallel with functional differentiation, the liver establishes three dimensional tissue structures. In particular, establishment of the bile excretion system consisting of bile canaliculi of hepatocytes and bile ducts of cholangiocytes is critical to maintain healthy tissue status. This is because hepatocytes produce bile as they functionally mature, and if allowed to remain within the liver tissue can lead to cytotoxicity. In this review, we focus on epithelial tissue morphogenesis in the perinatal period and cholestatic liver diseases caused by abnormal development of the biliary system.

T-Bet Deficiency Attenuates Bile Duct Injury in Experimental Biliary Atresia

Biliary atresia (BA) is an obstructive neonatal cholangiopathy leading to liver cirrhosis and end stage liver disease. A Kasai portoenterostomy may restore biliary drainage, but most patients ultimately require liver transplantation for survival. At diagnosis, immune cells within the liver of patients with BA demonstrate a T-helper 1 (Th1) inflammatory profile similar to rhesus rotavirus (RRV)-infected mice livers developing BA. The transcription factor Tbx21 (T-bet) is essential for induction of a Th1 immune response in both the adaptive and innate immune system. Here we used animals with targeted deletion of the T-bet gene to determine its role in the progression of BA. Infection of newborn T-bet knockout (KO) pups with RRV resulted in a decreased Th1 inflammatory chemokine/cytokine profile when compared to infected wild-type mice. Analysis of the mononuclear cells profile from T-bet KO mice revealed both a significant decrease in the total number of CD3, CD4, and CD8 T cells and their effector molecules granzyme A, perforin, and FasL. Even though the percentage of T-bet KO mice displaying symptoms of an obstructive cholangiopathy and overall mortality rate was not different compared to wild-type mice, the extrahepatic bile ducts of T-bet KO mice remained patent.

Biliary Atresia/Neonatal Cholestasis: What is in the Horizon?

"Biliary atresia (BA) is a common cause of jaundice in infancy. There is increasing evidence that newborn screening with direct or conjugated bilirubin leads to earlier diagnosis. Although the Kasai portoenterostomy is the primary treatment, there are scientific advances in adjuvant therapies. As pediatric patients transition to adult care, multidisciplinary care is essential, given the complexity of this patient population."

Management of biliary atresia: To transplant or not to transplant

Kasai procedure (KP) and liver transplantation (LT) represent the only therapeutic options for patients with biliary atresia (BA), the most common indication for LT in the pediatric population. However, KP represents by no means a radical option but rather a bridging one, as nearly all patients will finally require a liver graft. More and more experts in the field of transplant surgery propose that maybe it is time for a paradigm change in BA treatment and abandon KP as transplantation seems inevitable. Inadequacy of organs yet makes this option currently not feasible, so it seems useful to find ways to maximize the efficacy of KP. In previous decades, multiple studies tried to identify these factors which opt for better results, but in general, outcomes of KP have not improved to the level that was anticipated. This review provides the framework of conditions which favor native liver survival after KP and the ones which optimize a positive LT outcome. Strategies of transition of care at the right time are also presented, as transplantation plays a key role in the surgical treatment of BA. Future studies and further organization in the transplant field will allow for greater organ availability and better outcomes to be achieved for BA patients.

RRV-induced biliary atresia in neonatal mice involves CD8 + T lymphocyte killer cells and the Notch signaling pathway

BACKGROUND

Persistent inflammation induced by viral infection may contribute to the pathogenesis of biliary atresia (BA). Moreover, CD4⁺ helper cells and CD8⁺ killer cells are the main effector cells involved in BA and intrahepatic bile duct injuries.

OBJECTIVE

Thus, we aimed to explore the dynamics of inflammatory cell infiltration and inflammation-regulated pathways in liver-specific inflammatory responses.

METHODS

Neonatal Balb/C mice were intraperitoneally infected with 1 × 10⁶ PFU rhesus rotavirus (RRV; BA + group), 1 × 10⁵ PFU RRV (BA- group), or DMEM (control group). Mice were sacrificed 7 or 14 days post-infection and their bile ducts, livers, and spleen-derived tissues were examined via H & E staining. The number of CD4⁺T lymphocytes helper cells (CD4⁺Th), CD8⁺T lymphocytes killer cells (CD8⁺Tc), natural killer (NK) cells, and macrophages (Mac) in the liver and spleen were quantified by flow cytometry. The expression of inflammatory genes was analyzed via a PCR-array. Western blotting was conducted to quantify the protein expression of Notch receptor active fragments (NICD). Finally, some mice were injected with DAPT (a γ-secretase inhibitor) 12 h post-infection followed by analysis of liver and bile duct tissues after 14 days.

RESULTS

The numbers of CD4⁺Th cells were increased in the livers of BA- mice after 14 days (P < 0.05). After RRV infection, the number of CD8⁺Tc, CD4⁺Th, NK, and Mac were increased in the livers of BA + mice after 7 and 14 days. Notably, NK cell numbers remained elevated in the BA + group, but the number of Mac first increased and then decreased in both the treatment groups. PCR-array analyses indicated that the expression of many genes related to T cell proliferation and differentiation significantly increased in the livers of BA. The most upregulated gene was Jagged2 (20.34-fold). Increased NICD (Notch receptor active fragments) protein expression was found in the BA + group. Finally, DAPT injection could reduce inflammation, CD8⁺Tc infiltration, NICD expression, and bile duct damage after RRV infection. We found that CD8⁺Tc played the most important role in damaging bile ducts and promoting BA.

CONCLUSION

The DAPT-based intervention could reduce expression of CD8⁺Tc and bile duct damage in BA mouse livers post-RRV infection. We believe that the Notch signaling pathway regulates CD8⁺Tc functions and inflammatory dynamics in BA mouse livers.

Programmed cell death protein-1 (PD-1) protects liver damage by suppressing IFN-γ expression in T cells in infants and neonatal mice

Background

Biliary atresia (BA) is a severe cholangiopathy possibly resulting from virus-induced and immune-mediated injury of the biliary system. IFN-γ, secreted from CD4⁺ Th1 cells and CD8⁺ cytotoxic T cells, is a major mediator of liver pathology. Programmed death protein-1 (PD-1) signaling suppresses T cell function. However, how PD-1 modify T cell function in BA remains incompletely understood.

Methods

Frequencies of PD-1 expressing CD4⁺ and CD8⁺ T cells were analyzed in the liver and blood from BA and control subjects. Associations of PD-1⁺CD4⁺/CD8⁺T cell abundances with liver function indices were measured. Function of PD-1 was measured by administration of an anti-PD-1 antibody in a Rhesus Rotavirus (RRV)-induced BA model. Survival, histology, direct bilirubin, liver immune cell subsets and cytokine production were analyzed.

Results

PD-1 was significantly upregulated in CD4⁺ and CD8⁺ T cells in patients with BA compared with control subjects. PD-1 expression in T cells was negatively associated with IFN-γ concentration in liver (PD-1⁺CD4⁺T cells in liver vs. IFN-γ concentration, r = − 0.25, p = 0.05; PD-1⁺CD8⁺T cells in liver vs. IFN-γ concentration, r = − 0.39, p = 0.004). Blockade of PD-1 increased IFN-γ expression in CD4⁺ T and CD8⁺ T cells (RRV vs. anti-PD-1 treated RRV mice: 11.59 ± 3.43% vs. 21.26 ± 5.32% IFN-γ⁺ in hepatic CD4⁺T cells, p = 0.0003; 9.33 ± 4.03% vs. 22.55 ± 7.47% IFN-γ⁺ in hepatic CD8⁺T cells, p = 0.0001), suppressed bilirubin production (RRV vs. anti-PD-1 treated RRV mice: 285.4 ± 47.93 vs. 229.8 ± 45.86 μmol/L total bilirubin, p = 0.01) and exacerbated liver immunopathology.

Conclusions

PD-1 plays a protective role in infants with BA by suppressing IFN-γ production in T cells. Increasing PD-1 signaling may serve as a therapeutic strategy for BA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02794-x.

Prognostic and Pathophysiologic Significance of IL-8 (CXCL8) in Biliary Atresia

Interleukin (IL)-8 (CXCL8), a chemokine involved in neutrophil recruitment, has been implicated in ductular reaction and liver fibrogenesis. We studied liver and serum IL-8 expression in a large biliary atresia (BA) cohort and explored its prognostic and pathophysiological potential. IL-8 expression was assessed in liver utilizing quantitative polymerase chain reaction (qPCR), immunohistochemistry and in situ hybridization and in serum using an enzyme-linked immunosorbent assay, among 115 BA patients, 10 disease controls and 68 normal controls. Results were correlated to portoenterostomy (PE) outcomes, biochemical and histological liver injury, transcriptional markers of fibrosis and cholangiocytes, and expression of other related cytokines. IL-8 was markedly overexpressed in liver and serum of BA patients at PE (n = 88) and in serum samples obtained during postoperative follow-up (n = 40). IL-8 expression in the liver was predominantly in cholangiocytes within areas of ductular reaction. Liver IL-8 mRNA expression correlated positively with its serum concentration, bile ductular proliferation, Metavir fibrosis stage, and transcriptional markers of activated myofibroblasts (ACTA2) and cholangiocytes (KRT19). Taken together, IL-8 may mediate liver injury in BA by promoting ductular reaction and associated liver fibrogenesis. Prognostic value of serum IL-8 to predict native liver survival was limited and confined to the postoperative period after PE.

Immunophenotypic analysis of the distribution of hepatic macrophages, lymphocytes and hepatic stellate cells in the adult rat liver

The liver consists of parenchymal hepatocytes and non-parenchymal cells. Non-parenchymal cells, Kupffer cells, hepatic stellate cells and cholangiocytes have crucial roles in liver homeostasis and liver pathology. To establish baseline data, this study investigated immunohistochemically the distribution of non-parenchymal cells in perivenular areas (PV), periportal areas (PP) and Glisson's sheath (GS) of adult rat liver. Liver tissues were collected from the left lateral lobe of rats. CD163-positive macrophages were seen along the sinusoid of PV and PP areas, indicating Kupffer cells. Double immunofluorescence showed, Kupffer cells partly co-expressed CD68 and MHC class II antigens in the liver. The numbers of Kupffer cells were significantly high in PP areas as compared with PV or GS areas. CD68-positive exudative macrophages were highly localized in PP and GS areas and a comparatively low PV area. MHC class II-positive dendritic cells (activated macrophages) were localized mainly in GS. Granzyme B-positive NK cells were mainly localized in the Glisson's sheath. CD3-positive T cells and CD20-positive B cells were distributed along the sinusoids of the PP and PV areas of hepatic lobules. Vimentin and glial fibrillary acidic protein (GFAP)-positive hepatic stellate cells were localized along sinusoids in the hepatic lobules of the liver. Cholangiocytes reacting to cytokeratin 19 were seen on interlobular bile ducts in Glisson's sheath of the liver. This study shows that heterogeneous macrophage populations, liver-resident lymphocytes and hepatic stellate cells localized in PP and PV areas or GS areas of the liver with cells specific patterns.

Transcriptional profiling of pediatric cholestatic livers identifies three distinct macrophage populations

Background & aims

Limited understanding of the role for specific macrophage subsets in the pathogenesis of cholestatic liver injury is a barrier to advancing medical therapy. Macrophages have previously been implicated in both the mal-adaptive and protective responses in obstructive cholestasis. Recently two macrophage subsets were identified in non-diseased human liver; however, no studies to date fully define the heterogeneous macrophage subsets during the pathogenesis of cholestasis. Here, we aim to further characterize the transcriptional profile of macrophages in pediatric cholestatic liver disease.

Methods

We isolated live hepatic immune cells from patients with biliary atresia (BA), Alagille syndrome (ALGS), and non-cholestatic pediatric liver by fluorescence activated cell sorting. Through single-cell RNA sequencing analysis and immunofluorescence, we characterized cholestatic macrophages. We next compared the transcriptional profile of pediatric cholestatic and non-cholestatic macrophage populations to previously published data on normal adult hepatic macrophages.

Results

We identified 3 distinct macrophage populations across cholestatic liver samples and annotated them as lipid-associated macrophages, monocyte-like macrophages, and adaptive macrophages based on their transcriptional profile. Immunofluorescence of liver tissue using markers for each subset confirmed their presence across BA (n = 6) and ALGS (n = 6) patients. Cholestatic macrophages demonstrated reduced expression of immune regulatory genes as compared to normal hepatic macrophages and were distinct from macrophage populations defined in either healthy adult or pediatric non-cholestatic liver.

Conclusions

We are the first to perform single-cell RNA sequencing on human pediatric cholestatic liver and identified three macrophage subsets with distinct transcriptional signatures from healthy liver macrophages. Further analyses will identify similarities and differences in these macrophage sub-populations across etiologies of cholestatic liver disease. Taken together, these findings may allow for future development of targeted therapeutic strategies to reprogram macrophages to an immune regulatory phenotype and reduce cholestatic liver injury.

An insight into the mechanism and molecular basis of dysfunctional immune response involved in cholestasis

Cholestasis is one of the most common clinical symptom of liver diseases. If patients do not receive effective treatment, cholestasis can evolve into liver fibrosis, cirrhosis and ultimately liver failure requiring liver transplantation. Currently, only ursodeoxycholic acid, obeticholic acid and bezafibrate are FDA-approved drugs, thereby requiring a breakthrough in new mechanisms and therapeutic development. Inflammation is one of the common complications of cholestasis. Hepatic accumulation of toxic hydrophobic bile acids is a highly immunogenic process involving both resident and immigrating immune cells. And the resulting inflammation may further aggravate hepatocyte injury. Though, great investigations have been made in the immune responses during cholestasis, the relationship between immune responses and cholestasis remains unclear. Moreover, scarce reviews summarize the immune responses during cholestasis and the efficacy of therapies on immune response. The main purpose of this paper is to review the existing literature on dysfunctional immune response during cholestasis and the effect of treatment on immune response which may provide an insight for researchers and drug development.

Current Concepts of Biliary Atresia and Matrix Metalloproteinase-7: A Review of Literature

Biliary atresia (BA) is a rare cholangiopathy of infancy in which the bile ducts obliterate, leading to profound cholestasis and liver fibrosis. BA is hypothesized to be caused by a viral insult that leads to over-activation of the immune system. Patients with BA are surgically treated with a Kasai portoenterostomy (KPE), which aims to restore bile flow from the liver to the intestines. After KPE, progressive liver fibrosis is often observed in BA patients, even despite surgical success and clearance of their jaundice. The innate immune response is involved during the initial damage to the cholangiocytes and further differentiation of the adaptive immune response into a T-helper 1 cell (Th1) response. Multiple studies have shown that there is continuing elevation of involved cytokines that can lead to the progressive liver fibrosis. However, the mechanism by which the progressive injury occurs is not fully elucidated. Recently, matrix metalloproteinase-7 (MMP-7) has been investigated to be used as a biomarker to diagnose BA. MMPs are involved in extracellular matrix (ECM) turnover, but also have non-ECM related functions. The role of MMP-7 and other MMPs in liver fibrosis is just starting to be elucidated. Multiple studies have shown that serum MMP-7 measurements are able to accurately diagnose BA in a cohort of cholestatic patients while hepatic MMP-7 expression correlated with BA-related liver fibrosis. While the mechanism by which MMP-7 can be involved in the pathophysiology of BA is unclear, MMP-7 has been investigated in other fibrotic pathologies such as renal and idiopathic pulmonary fibrosis. MMP-7 is involved in Wnt/β-catenin signaling, reducing cell-to-cell contact by shedding of E-cadherin, amplifying inflammation and fibrosis via osteopontin (OPN) and TNF-α while it also appears to play a role in induction of angiogenesis This review aims to describe the current understandings of the pathophysiology of BA. Subsequently, we describe how MMP-7 is involved in other pathologies, such as renal and pulmonary fibrosis. Then, we propose how MMP-7 can potentially be involved in BA. By doing this, we aim to describe the putative role of MMP-7 as a prognostic biomarker in BA and to provide possible new therapeutic and research targets that can be investigated in the future.

Synthetic retinoid AM80 inhibits IL-17 production of gamma delta T cells and ameliorates biliary atresia in mice

BACKGROUND & AIMS

Recent evidence suggests that Interleukin (IL)-17-producing gamma delta ( γδ ) T cells are the dominant pathogenic cellular component in designated autoimmune or inflammatory diseases, including biliary atresia (BA). We have previously demonstrated that retinoids effectively suppress T-helper cell (Th) 17 differentiation.

METHODS

Here, we established an in vitro system, enabling investigations of the effect of AM80 on the IL-17 production of γδ T cells. Additionally, we tested the therapeutic effect of AM80 in the Rotavirus-induced mouse model of BA. Co-incubation of γδ T cells with IL-23 and anti-CD28 mAb proved most effective in inducing an IL-17 response in vitro. The effect of AM80 on human CCR6+CD26+ V δ 2 cells was assessed by flow cytometry.

RESULTS

AM80 efficiently reduced IL-17 production by murine γδ T cells and the expression of the master transcription factor Retinoid-Orphan-Receptor- γ t (ROR γτ ) in a dose-dependent manner. The fraction of human CCR6+CD26+ V δ 2 cells was significantly reduced by co-incubation with AM80. Moreover, AM80 also inhibited IL-17 production by liver-infiltrating γδ T cells isolated from animals suffering from BA. Intraperitoneal treatment with AM80 ameliorated BA-associated inflammation. However, AM80 treatment was not sufficient to control disease progression in the murine model, despite reduced inflammatory activity in the animals.

CONCLUSIONS

Retinoids are very efficient in down-regulating IL-17 production by γδ T cells in vitro and, to a lesser extent, in the BA mouse model. However, retinoids do not suffice for the control of disease progression. Thus, our data suggest that IL-17 is not the only factor contributing to the pathogenesis of BA.

LAY SUMMARY

Biliary atresia (BA) is a rare disease which affects infants, causing progressive liver failure in most children, and is the most common indication for paediatric liver transplantation. We have previously demonstrated that IL-17, produced by γδ T cells, contributes to hepatic inflammation in the murine model of BA and is increased in the livers of infants suffering from the disease. In the study at hand, we demonstrate that treatment with AM80, a synthetic retinoid with superior pharmacological properties, effectively inhibits the IL-17 production of gamma delta T cells without generating systemic immunosuppression. Although all-trans retinoic acid (ATRA) has been demonstrated to suppress differentiation of IL-17-producing conventional T-helper cells (Th17) in vitro, the therapeutic application of ATRA in vivo is limited by the compound's potential side effects caused by its instability and lack of receptor specificity. Our study is the first to show that AM80 suppresses the IL-17 production of γδ T cells in a very efficient manner and that hepatic inflammation is ameliorated in mice suffering from BA. However, AM80 treatment does not suffice to block the disease progression. We conclude that factors other than IL-17 drive the progressive inflammation in BA. The addition of retinoids to the treatment regime of children suffering from BA might decrease the disease burden; however, further research is needed to clarify the pathomechanism and possible therapeutic interventions in humans.

Liver Immune Profiling Reveals Pathogenesis and Therapeutics for Biliary Atresia

Biliary atresia (BA) is a severe cholangiopathy that leads to liver failure in infants, but its pathogenesis remains to be fully characterized. By single-cell RNA profiling, we observed macrophage hypo-inflammation, Kupffer cell scavenger function defects, cytotoxic T cell expansion, and deficiency of CX3CR1⁺effector T and natural killer (NK) cells in infants with BA. More importantly, we discovered that hepatic B cell lymphopoiesis did not cease after birth and that tolerance defects contributed to immunoglobulin G (IgG)-autoantibody accumulation in BA. In a rhesus-rotavirus induced BA model, depleting B cells or blocking antigen presentation ameliorated liver damage. In a pilot clinical study, we demonstrated that rituximab was effective in depleting hepatic B cells and restoring the functions of macrophages, Kupffer cells, and T cells to levels comparable to those of control subjects. In summary, our comprehensive immune profiling in infants with BA had educed that B-cell-modifying therapies may alleviate liver pathology.

The synthetic toxin biliatresone causes biliary atresia in mice

Exposure to environmental toxins may be responsible for biliary atresia. The focus of this study was to investigate the effect of biliatresone on the development of the hepatobiliary system in mice. We successfully synthesized biliatresone with a purity of 98% and confirmed its biliary toxicity. Exposure to high doses of biliatresone caused abortion or death in pregnant mice. Neonatal mice injected with biliatresone developed clinical signs of biliary obstruction, and dysplasia or the absence of extrahepatic biliary tract lumen, which confirmed the occurrence of biliary atresia. In the portal tract of biliary atresia mice, signs of infiltration of inflammatory cells and liver fibrosis were observed. The signature of extrahepatic biliary gene expression in these mice mainly involved the cell adhesion process, and hepatic RNA-seq was highly linked to transcriptional evidence of oxidative stress. When compared with the control group, hepatic glutathione levels were markedly reduced after biliatresone injection. Taken together, these data confirm that biliatresone causes severe developmental abnormalities of the hepatobiliary system in mice. Furthermore, decreased levels of glutathione may play a mechanistic role in the pathogenesis of liver fibrosis in biliatresone-induced experimental biliary atresia.

Biliary atresia: Potential for a new decade

Biliary atresia is characterised as an obliterative cholangiopathy of both extra-and intra-hepatic bile ducts. There is marked aetiological heterogeneity with a number of different variants, some syndromic and others perhaps virally-mediated. Current research aims to try and define possible mechanisms and pathogenesis though an actual breakthrough remains elusive. There has been little in the way of surgical advances beyond subtle variations in the Kasai portoenterostomy and laparoscopic equivalents have no declared advantage and have yet to prove equivalence in measures of outcome. The next target has been to maximise potential with better adjuvant therapy, though the evidence base for most currently available therapies such as steroids and ursodeoxycholic acid remains limited. Still high-dose steroid use is widespread, certainly in Europe and the Far East. Clearance of jaundice can be achieved in 50-60% of those subjected to portoenterostomy at <70 days and should be an achievable benchmark. Transplantation is a widely available "rescue" therapy though whether it should be an alternative as a primary procedure is arguable but becoming increasingly heard. The aim of clinical practice remains to get these infants for surgery as early as is possible though this can be difficult to accomplish in practice, and "low-cost" screening projects using stool colour charts have been limited outside of Taiwan and Japan. Centralisation of resources (medical and surgical) is associated with a diminution of time to portoenterostomy but application has been limited by entrenched health delivery models or geographical constraints.

Using next-generation sequencing of microRNAs to identify host and/or pathogen nucleic acid signatures in samples from children with biliary atresia - a pilot study

Biliary atresia (BA) is a progressive disease affecting infants resulting in inflammatory obliteration and fibrosis of the extra- and intra-hepatic biliary tree. BA may be grouped into type 1 isolated; type 2 syndromic, where other congenital malformations may be present; type 3 cystic BA, where there is cyst formation within an otherwise obliterated biliary tree; and cytomegalovirus-associated BA. The cause of BA is unclear, with immune dysregulation, inflammation and infection, particularly with cytomegalovirus (CMV), all implicated. In this study a total of 50/67 samples were tested for CMV DNA using quantitative real-time PCR. Ten liver tissue and 8 bile samples from 10 patients representing the range of BA types were also analysed by next-generation sequencing. CMV DNA was found in 8/50 (16 %) patients and a total of 265 differentially expressed microRNAs were identified. No statistically significant differences between the various types of BA were found. However, differences were identified in the expression patterns of 110 microRNAs in bile and liver tissue samples (P<0.05). A small number of bacterial and viral sequences were found, although their relevance to BA remains to be determined. No direct evidence of viral causes of BA were found, although clear evidence of microRNAs associated with hepatocyte and cholangiocyte differentiation together with fibrosis and inflammation were identified. These include miR-30 and the miR-23 cluster (liver and bile duct development) and miR-29, miR-483, miR-181, miR-199 and miR-200 (inflammation and fibrosis).

Rotavirus Reassortant-Induced Murine Model of Liver Fibrosis Parallels Human Biliary Atresia

BACKGROUND AND AIMS

Biliary atresia (BA) is a devastating neonatal cholangiopathy that progresses to fibrosis and end-stage liver disease by 2 years of age. Portoenterostomy may reestablish biliary drainage, but, despite drainage, virtually all afflicted patients develop fibrosis and progress to end-stage liver disease requiring liver transplantation for survival.

APPROACH AND RESULTS

In the murine model of BA, rhesus rotavirus (RRV) infection of newborn pups results in a cholangiopathy paralleling human BA and has been used to study mechanistic aspects of the disease. Unfortunately, nearly all RRV-infected pups succumb by day of life 14. Thus, in this study we generated an RRV-TUCH rotavirus reassortant (designated as T^R(VP2,VP4) ) that when injected into newborn mice causes an obstructive jaundice phenotype with lower mortality rates. Of the mice that survived, 63% developed Ishak stage 3-5 fibrosis with histopathological signs of inflammation/fibrosis and bile duct obstruction.

CONCLUSIONS

This model of rotavirus-induced neonatal fibrosis will provide an opportunity to study disease pathogenesis and has potential to be used in preclinical studies with an objective to identify therapeutic targets that may alter the course of BA.

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.

Clinical Value of Serum Interleukin-33 Biomarker in Infants With Neonatal Cholestasis

OBJECTIVES

The present study aimed to estimate the value of serum interleukin-33 (IL-33) levels in infants with cholestasis, correlate serum IL-33 levels with the clinicopathological profile of infants with cholestasis, and compare its level with that of healthy infants who served as control.

METHODS

Sixty infants with cholestasis were enrolled in the present study and divided into biliary atresia (BA) group and non-BA group, in addition to 30 healthy infants as a control group. All infants were analyzed for their clinical and biochemical features, histopathological profile, and serum level of IL-33 by enzyme-linked immune sorbent assay.

RESULTS

Serum level of IL-33 in BA group (median 48.0, interquartile range: 28.9-106.2) was significantly higher than that of the non-BA group (median 17.3, interquartile range: 13.7-18.8 pg/mL) and both were higher than that of the control group. There was a positive correlation between serum IL-33 and aspartate aminotransferase, alanine aminotransferase, bilirubin (total and direct) levels, and fibrosis stage among the BA group. Serum IL-33 at a cut-off value of 20.8 pg/mL can detect BA with a specificity of 95% and a sensitivity of 96.7%.

CONCLUSION

The significantly higher production of IL-33 in patients with BA compared to non-BA suggests a potential role of IL-33 for initiation and progression of the disease process, also, IL-33 may have a diagnostic role in infants with BA.

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.

[Staging of liver fibrosis in biliary atresia : Comparison of Chevallier and Ishak score as well as automated evaluation]

BACKGROUND

Biliary atresia (BA) is a rare disease of the newborn, resulting in liver cirrhosis due to obliterative cholangiopathy. Liver biopsies are commonly performed in order to confirm the diagnosis and in order to stage fibrosis.

OBJECTIVES

The present study intended to analyze two established scores for evaluating liver fibrosis focusing on the interobserver variability as well as the prognostic reliability towards the time of liver transplantation.

MATERIALS AND METHODS

Liver biopsies of BA patients between 2012 and 2015 were evaluated retrospectively by two pathologists at the Hannover Medical School (MHH) and the RWTH Aachen University Hospital. Fibrosis was measured using Ishak and Chevallier scores. Furthermore, a computerized automatically algorithm-based analyzation (ABAA) was performed. Results were evaluated towards the time point of liver transplantation and hepatoportoenterostomy (HPE).

RESULTS

Overall, 34 liver biopsies were analyzed. The Ishak score showed a remarkable interobserver variability (Κ_W = 0.68) while the Chevallier score was proven to have a poor interobserver variability (Fleiss' Κappa = -0.01). However, both scores were correlated positively, as was the ABAA (p < 0.001). Regarding prognostic reliability, ROC analyses of the Ishak score revealed the best validity towards an early liver transplantation within 12 months (AUC 0.813, p = 0.011). In addition, an increased Ishak score ≥4 reduced the survival time with the native liver (hazard ratio 6.6 [95% CI 1.9-23.3]).

CONCLUSIONS

The Ishak score was revealed to have the best interobserver variability as well as prognostic validity towards an early liver transplantation in BA patients. Due to its easy applicability, the Ishak score was proven superior in comparison to the Chevallier score and ABAA. Therefore, use of the Ishak score is recommended in daily clinical routine for analyzing liver biopsies in BA patients.

CD4+T Cell Subset Profiling in Biliary Atresia Reveals ICOS- Regulatory T Cells as a Favorable Prognostic Factor

Biliary atresia (BA) is a destructive pediatric liver disease and CD4+T cell activation is demonstrated to play an important role in BA. However, a comprehensive scenario regarding the involvement of CD4+T cell subsets to the development of BA remains unclear. Here, we aim to explore the infiltration of CD4+T cell subsets and their clinical significance in BA. In the present study, thirty BA liver samples were collected during surgery and were divided into good (BA1, n = 16) and poor prognosis (BA2, n = 14), with samples from choledochal cyst patients (n = 8) as control. By using multiplex immunohistochemistry, we evaluated the infiltration level of CD4+T cell subsets in the portal areas. RT-qPCR and flow cytometry were further applied to explore detailed features of Treg subsets. We revealed that hepatic infiltrating Th1, Th2, Th17, and ICOS+Treg cells were significantly increased in BA patients compared to controls and were negatively associated with prognosis, while high infiltrating ICOS-Tregs showed a favorable outcome. Phenotypic analysis indicated that, in contrast to ICOS+Tregs, ICOS-Tregs were mainly CD45RAhiCD45ROlow, and preferentially expressed more CD73. Besides, RT-qPCR revealed elevated expression of CD25, CD73, TGF-β, and BCL-2 genes in ICOS-Tregs. Finally, functional assay confirmed that ICOS-Tregs had a higher suppressive capacity to cytokine secretion and were more resistant to apoptosis in vitro. Collectively, we demonstrate that a mixed immune response is involved in BA pathogenesis, and the globally enhanced effector CD4+T cell response is associated with unfavorable prognosis, highly suppressive ICOS-Tregs is a protective factor and may serve an important reference to predict prognosis.

A wave of Foxp3+ regulatory T cell accumulation in the neonatal liver plays unique roles in maintaining self-tolerance

Newborn animals require tightly regulated local and systemic immune environments to govern the development and maturation of multiple organs/tissues even though the immune system itself is far from mature during the neonatal period. Regulatory T cells (Tregs) are essential for maintaining immune tolerance/homeostasis and modulating inflammatory responses. The features of Tregs in the neonatal liver under steady-state conditions are not well understood. The present study aimed to investigate the phenotype, functions, and significance of neonatal Tregs in the liver. We found a wave of thymus-derived Treg influx into the liver during 1-2 weeks of age. Depletion of these Tregs between days 7 and 11 after birth rapidly resulted in Th1-type liver inflammation and metabolic disorder. More Tregs in the neonatal liver than in the spleen underwent MHC II-dependent activation and proliferation, and the liver Tregs acquired stronger suppressive functions. The transcriptomic profile of these neonatal liver Tregs showed elevated expression of PPARγ and T-bet and features of Tregs that utilize lipid metabolic machinery and are capable of regulating Th1 responses. The accumulation of Tregs with unique features in the neonatal liver is critical to ensure self-tolerance and liver maturation.

A Phase I/IIa Trial of Intravenous Immunoglobulin Following Portoenterostomy in Biliary Atresia

OBJECTIVES

Biliary atresia (BA) is a progressive neonatal fibroinflammatory cholangiopathy. We hypothesized that intravenous immunoglobulin (IVIg) would be safe, feasible, acceptable, and efficacious for the treatment of BA. The primary objective of this study was to establish the feasibility, acceptability, and safety profile of IVIg administration after hepatoportoenterostomy (HPE) in BA. The secondary objective was to determine the treatment efficacy of IVIg based on good bile drainage and survival with the native liver.

METHODS

A multicenter, prospective, open-labeled, phase I/IIA trial of IVIg was conducted, with 1 g/kg/dose of IVIg infused at 3-5, 30, and 60 days post-HPE, and subjects followed for 360 days post-HPE. Twenty-nine participants completed the study.

RESULTS

Administration of IVIg infusions was feasible and acceptable in 79%. None of the serious adverse events (SAEs) were directly related to IVIg infusions; however, 90% of participants had an SAE. Compared with a historical placebo-arm group, there was no significant increase in the proportion of IVIg participants with a serum total bilirubin <1.5 mg/dL at 90, 180, or 360 days post-HPE. Survival with the native liver in the IVIg participants showed no significant benefit over the historical placebo arm, with a difference at 360 days of -11.9% (IVIg: 58.6%, placebo: 70.5%; 90% UCB: 2.1%; P > 0.05).

CONCLUSIONS

Although IVIg infusions in infants with BA post-HPE were feasible, acceptable and safe, there was no trend to lower bilirubin levels or improved 360-day survival with the native liver.

CLINICAL TRIAL

Safety Study of Intravenous Immunoglobulin Post-Portoenterostomy in Biliary Atresia; #NCT01854827.

Correlation of Immune Markers With Outcomes in Biliary Atresia Following Intravenous Immunoglobulin Therapy

Biliary atresia is a progressive fibroinflammatory cholangiopathy of infancy that is associated with activation of innate and adaptive immune responses targeting bile ducts. A recently completed multicenter phase I/IIA trial of intravenous immunoglobulin in biliary atresia did not improve serum total bilirubin levels at 90 days after hepatoportoenterostomy or survival with the native liver at 1 year. A mechanistic aim of this trial was to determine if the peripheral blood immunophenotype was associated with clinical outcomes. Flow cytometry of peripheral blood cell markers (natural killer [NK], macrophage subsets, T‐ and B‐cell subsets, regulatory T cells), neutrophils, and activation markers (clusters of differentiation [CD]38, CD69, CD86, human leukocyte antigen‐DR isotype [HLA‐DR]) was performed on 29 patients with biliary atresia at baseline and at 60, 90, 180, and 360 days after hepatoportoenterostomy. Plasma cytokines and neutrophil products were also measured. Spearman correlations of change of an immune marker from baseline to day 90 with change in serum bilirubin revealed that an increase in total bilirubin correlated with 1) increased percentage of HLA‐DR⁺CD38⁺ NK cells and expression of NK cell activation markers CD69 and HLA‐DR, 2) decreased percentage of regulatory T cells, and 3) increased interleukin (IL)‐8 and associated neutrophil products (elastase and neutrophil extracellular traps). Cox modeling revealed that the change from baseline to day 60 of the percentage of HLA‐DR⁺CD38⁺ NK cells and plasma IL‐8 levels was associated with an increased risk of transplant or death by day 360. Conclusion: Poor outcomes in biliary atresia correlated with higher peripheral blood NK cells and IL‐8 and lower regulatory T cells. Future studies should include immunotherapies targeting these pathways in order to protect the biliary tree from ongoing damage.

Oligoclonal immunoglobulin repertoire in biliary remnants of biliary atresia

Biliary atresia (BA) is a neonatal cholestatic liver disease that is the leading cause of pediatric liver transplantation, however, the mechanism of disease remains unknown. There are two major forms of BA: isolated BA (iBA) comprises the majority of cases and is thought to result from an aberrant immune response to an environmental trigger, whereas syndromic BA (BASM) has associated malformations and is thought to arise from a congenital insult. To determine whether B cells in BA biliary remnants are antigen driven, we examined the immunoglobulin (Ig) repertoire of diseased tissue from each BA group. Deep sequencing of the Ig chain DNA was performed on iBA and BASM biliary remnants and lymph nodes obtained from the Childhood Liver Disease Research Network (ChiLDReN) repository. Statistical analysis of the Ig repertoire provided measures of Ig clonality and the Ig phenotype. Our data demonstrate that B cells infiltrate diseased iBA and BASM biliary remnant tissue. The Ig repertoires of iBA and BASM disease groups were oligoclonal supporting a role for an antigen-driven immune response in both sub-types. These findings shift the current understanding of BA and suggest a role for antigen stimulation in early iBA and BASM disease pathogenesis.

Biliary Atresia: Clinical and Research Challenges for the Twenty-First Century

Biliary atresia (BA) is a fibroinflammatory disease of the intrahepatic and extrahepatic biliary tree. Surgical hepatic portoenterostomy (HPE) may restore bile drainage, but progression of the intrahepatic disease results in complications of portal hypertension and advanced cirrhosis in most children. Recognizing that further progress in the field is unlikely without a better understanding of the underlying cause(s) and pathogenesis of the disease, the National Institutes of Diabetes and Digestive and Kidney Diseases (NIDDK) sponsored a research workshop focused on innovative and promising approaches and on identifying future areas of research. Investigators discussed recent advances using gestational ultrasound and results of newborn BA screening with serum direct (conjugated) bilirubin that support a prenatal onset of biliary injury. Experimental and human studies implicate the toxic properties of environmental toxins (e.g., biliatresone) and of viruses (e.g., cytomegalovirus) to the biliary system. Among host factors, sequence variants in genes related to biliary development and ciliopathies, a notable lack of a cholangiocyte glycocalyx and of submucosal collagen bundles in the neonatal extrahepatic bile ducts, and an innate proinflammatory bias of the neonatal immune system contribute to an increased susceptibility to damage and obstruction following epithelial injury. These advances form the foundation for a future research agenda focused on identifying the environmental and host factor(s) that cause BA, the potential use of population screening, studies of the mechanisms of prominent fibrosis in young infants, determinations of clinical surrogates of disease progression, and the design of clinical trials that target subgroups of patients with initial drainage following HPE. (Hepatology 2018; 00:000-000).

Association of T-helper cell cytokine level with age in patients with biliary atresia: a preliminary study

BACKGROUND

The pathogenesis of biliary atresia (BA) is associated with an inflammatory process involving the biliary tree. This study aimed to investigate the association of T-helper cell cytokine levels with age in patients with BA.

METHODS

Twenty-eight patients with BA were divided into three groups according to their age (< 2 months, 2-3 months, and ≥ 3 months). All the patients underwent Kasai portoenterostomy. Blood samples were collected from the patients preoperatively, and the liver tissue specimens were obtained during surgery. We detected serum levels of interleukin (IL)-1β, IL-12p70, interferon (IFN)-γ, IL-6, IL-10, and transforming growth factor (TGF)-β1 and liver expression of IL-1β, IL-6, and TGF-β1.

RESULTS

The serum levels of IL-1β, IL-12p70, IL-6, and IL-10 in patients aged ≥ 3 months were significantly higher than those in patients aged < 2 months. There were no significant age-related differences in the IL-1β, IL-6 and TGF-β1 expression levels in the liver tissue of patients with BA.

CONCLUSIONS

The serum levels of IL-1β, IL-6, IL-10 and IL-12p70 showed significant age-related differences in patients with BA. Interpretation of the role of cytokines in BA needs to take patient's age into consideration.

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.

Macrophage-derived IL-1β/NF-κB signaling mediates parenteral nutrition-associated cholestasis

In infants intolerant of enteral feeding because of intestinal disease, parenteral nutrition may be associated with cholestasis, which can progress to end-stage liver disease. Here we show the function of hepatic macrophages and phytosterols in parenteral nutrition-associated cholestasis (PNAC) pathogenesis using a mouse model that recapitulates the human pathophysiology and combines intestinal injury with parenteral nutrition. We combine genetic, molecular, and pharmacological approaches to identify an essential function of hepatic macrophages and IL-1β in PNAC. Pharmacological antagonism of  IL-1 signaling or genetic deficiency in CCR2, caspase-1 and caspase-11, or IL-1 receptor (which binds both IL-1α and IL-1β) prevents PNAC in mice. IL-1β increases hepatocyte NF-κB signaling, which interferes with farnesoid X receptor and liver X receptor bonding to respective promoters of canalicular bile and sterol transporter genes (Abcc2, Abcb11, and Abcg5/8), resulting in transcriptional suppression and subsequent cholestasis. Thus, hepatic macrophages, IL-1β, or NF-κB may be targets for restoring bile and sterol transport to treat PNAC.

Role of viruses in biliary atresia: news from mice and men

Biliary atresia (BA) is still an enigmatic disease of unknown etiology and cryptic pathomechanism. Despite the fact that BA is rated among rare diseases, it represents the most frequent indication for pediatric liver transplantation. Although every effort is made to elucidate the origin of the ongoing deterioration of liver function, no breakthrough has so far been achieved, which switches the surgical but symptomatic therapy to a cause-oriented approach. The nowadays leading hypothesis focuses on hepatotropic virus as a triggering agent for an autoimmunological self-limiting inflammatory process along the entire biliary tree. The present review highlights the current state of research on the factor "viruses in biliary atresia" in both patients undergoing the Kasai procedure and the virus-induced BA mouse model.

Expression of intrahepatic CD3, CD4, and CD8 T cells in biliary atresia

Aim of the study

Assessment of the expression of cluster of differentiation (CD)3, CD4, and CD8 T cells in biliary atresia (BA) cases in comparison to neonatal cholestasis other than BA.

Material and methods

This study included 79 patients: 34 patients with BA (BA group) and 35 patients with neonatal cholestasis due to causes other than BA (cholestasis group), and 10 normal liver donor as a control group. Immunohistochemical staining or CD3, CD4, and CD8 T cells in liver tissues for the 3 groups were evaluated.

Results

Presence of clay stool, high gamma-glutamyl transferase levels, thrombocytosis, and non-contractibility of the gallbladder was the main clinical, laboratory, and radiological findings, distinguishing BA from other disorders causing neonatal cholestasis. Portal ductular proliferation, bile plugs in portal ductules, and advanced grades of fibrosis were more predominant in liver biopsy specimens of BA patients. The CD3+, CD4+, and CD8+ expression in patients with BA were significantly higher than in both cholestasis and control groups, while it was comparable in the cholestasis and control groups, with cutoff values of 25, 12, and 2.5 cells/portal tract, respectively, differentiating between BA and cholestatic patients.

Conclusions

Immune-mediated destruction of bile ducts is incriminated in the pathogenesis of BA. Lymphocytic infiltrate in portal tract is primarily composed of CD3, CD4, and CD8 T cells. Immunostaining of liver tissue for CD3, CD4, and CD8 T cells can help in ensuring diagnosis of BA.

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.

Infiltration of polarized macrophages associated with liver fibrosis in infants with biliary atresia

BACKGROUND/PURPOSE

Macrophages exert critical functions in liver homeostasis and have been proposed as potential targets in combatting fibrosis. We aimed to evaluate polarized functional status of liver infiltrated macrophages in infants with biliary atresia (BA).

METHODS

Immunohistochemical staining for CD68, CD163, and IRF5 was performed in 40 BA infants. Liver biopsies were scored for fibrosis and tested for association with clinical biochemical characteristics.

RESULTS

Developing lesions in BA liver progressively accumulated both CD163⁺ macrophages (M2) and IRF5⁺ macrophages (M1), while CD163 and IRF5 staining was stronger than the control group (p<0.001). In BA, the higher staining density of CD163 and CD68 was related with elevated serum conjugated bilirubin level (p=0.014 and 0.021, respectively). The CD163/IRF5 macrophages ratio was related with liver fibrosis scores (high vs. low, p=0.004).

CONCLUSIONS

We demonstrated a strong presence of polarized macrophages in BA liver, and macrophage phenotypes were involved in disease development. The balance of different polarized macrophage subpopulations may play a key role in fibrogenesis of BA.

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

Biliary atresia (BA) is a unique cholestatic disease of newborns with a background of exaggerated immune response in the liver of unknown mechanism. Three hypotheses have been proposed; autoimmune type of cholangiopathy triggered by virus infection, graft-versus-host disease type of immune-mediated disease associated with maternal microchimerism and ductal plate malformation theory. Researchers on virus infection theory have experimentally explored immune process causing cholangiopathy on murine models of this disease, while in maternal microchimerism hypothesis were detected maternal cells in the BA patients' liver, of which roles are yet to be determined. Ductal plate malformation theory is an intriguing hypothesis in the sense that it suggests the onset of this disease is in the first trimester. This theory can be secondary to either one of these two immune-related insults. In this review, four unique points are focused; (1) the timing of onset, (2) hepatitis-like pathological picture, (3) heterogenous atrophy of the liver segments when advanced, and (4) swollen lymph nodes at the porta hepatis. These unique clinicopahtological aspects of this disease should be well explained by these hypotheses.

Expression of programmed death-1 and its ligands in the liver of biliary atresia

BACKGROUND

An aberrant immune response is the predominant pathogenetic factor in biliary atresia (BA). Programmed death-1 (PD-1) and its two ligands, programmed death ligand-1 and programmed death ligand-2 (PD-L1 and PD-L2, respectively) play an important inhibitory role in immune reactions. We aimed to illustrate the expression of these molecules in BA.

METHODS

Liver specimens were obtained from infants with BA during the Kasai procedure (early BA) and liver transplantation (late BA). Intrahepatic expression of PD- 1, PD-L1, and PD-L2 were examined by immunostaining and compared with that in patients with neonatal hepatitis syndrome and normal controls. The correlation between the expression levels of these molecules in the liver and clinicopathological parameters was analyzed for each group.

RESULTS

Enhanced expression of PD-1 and its ligands occurred in the livers with early BA. In the BA-affected livers, PD-1 was correlated with the degree of peri-biliary inflammation, while PD-L2 was linked more directly with portal fibrosis. None of the three molecules was correlated with the prognosis of the Kasai procedure in patients with early BA.

CONCLUSIONS

Only PD-1 and PD-L1 are involved in the immune reactions of early BA. Elucidation of the detailed role of PD-L2 in BA requires further research.

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.

Interactions between Th1 cells and Tregs affect regulation of hepatic fibrosis in biliary atresia through the IFN-γ/STAT1 pathway

Regulatory T cells (Tregs) and CD4⁺ T helper (Th) cells have important roles in bile duct injury of biliary atresia (BA). However, their impacts on liver fibrosis are undefined. Between 2013 and 2016, 146 patients with various stages of BA were enrolled in this study. Peripheral blood, liver biopsy and lymph node samples were collected. Flow cytometry, magnetic cell sorting and immunostaining were used to characterize lymphocytes from BA patients. Deficiency of Tregs was observed along with increased Th1, Th2 and Th17 frequencies in the peripheral blood and livers of BA patients. The levels of peripheral and intrahepatic Th1 cells positively correlated with the stage of liver fibrosis. Furthermore, Th1 cells were located in close proximity to activated hepatic stellate cells (HSCs) and areas of fibrosis in BA livers. In culture, Th1 cells accelerated the proliferation and secretion of profibrogenic markers of HSCs through the IFN-γ/STAT1 pathway. Of note, Tregs blocked the Th1-stimulated effects on HSCs by inhibiting Th1-induced activation of STAT1. Consistent with the results of in vitro study, intrahepatic IFN-γ/STAT1 levels increased in relation to the severity of liver fibrosis in BA patients, and the altered balance between MMP2 and TIMP1 expressions in livers may contribute to increased deposition of extracellular matrix and fibrosis. Finally, to identify the effects of Th1 cells on Tregs, we demonstrated that Th1 cells upregulated the proportion of aTreg cells by secreting IFN-γ cytokine. Thus, aberrant Th1 immune responses in BA promote the proliferation and secretion of HSCs through the IFN-γ/STAT1 pathway. The regulation of HSCs by the interactions between Tregs and Th1 cells might be part of the mechanism underlying progressive liver fibrosis and may be a suitable target for therapy.

Chronic hepatitis B surface antigen seroclearance-related immune factors

The ultimate aims of the treatment of hepatitis B virus infection are the loss of hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody seroconversion. Unfortunately, these goals are rarely reached. Many factors are associated with HBsAg seroconversion, including genetic, immune, and viral factors. However, the mechanism of HBsAg seroclearance, and particularly the immune mechanism, is still difficult to elucidate. The immune factor interferon-α is currently the main antiviral therapy for chronic hepatitis B virus infection. However, a sustained shift from response of HBsAg to hepatitis B surface antibody seroconversion is rarely obtained. Recent studies have revealed that several of the newly identified immune factors are closely related to the removal of HBsAg. In this article, we review recent studies on these immune factors, their influence on hepatitis B progression, and HBsAg seroconversion.