The dendritic cell-T helper 17-macrophage axis controls cholangiocyte injury and disease progression in murine and human biliary atresia

Integration RNA bulk and single cell RNA sequencing to explore the change of glycolysis-related immune microenvironment and construct prognostic signature in head and neck squamous cell carcinoma

BACKGROUND

Glycolysis is an indispensable process for tumor cell,but the effect of glycolysis on the prognosis and immune cell infiltration of head and neck squamous cell carcinoma is not clear.

METHODS

Based on RNA bulk and single cell RNA sequencing data of head and neck squamous cell carcinoma from The Cancer Genome Atlas(TCGA) and GSE195832, the effect of glycolysis level on immune cell infiltration was analyzed. Then, we obtained the prognostic genes related to glycolysis through survival analysis to construct prognostic risk signature. Our sample and GSE65858 datasets are used as external verification datasets to verify the validity of the signature. Finally, we used Western blot and cell function assays to determine the relationship between risk genes and glycolysis and the function of prognostic genes.

RESULT

The level of glycolysis was related to the prognosis of head and neck tumors (P = 0.0044). The results of immune infiltration analysis of TCGA database showed that high level glycolysis subgroup had less infiltration of macrophages, T cells and monocytes. Results of single cell sequencing analysis validates the above results. Additionally, Five risk genes(MUCL1,TRIML2,RAB3B,SPINK6,IGSF11) were selected to construct signature.Risk score was an independent prognostic factor(P < 0.01). The external validation set also shows the same result. In vitro functional and Western blot assays confirmed that the above five genes affect tumor function and related to the process of glycolysis.

CONCLUSION

Glycolysis-related risk signatures can be used to predict the prognosis and immune infiltration of head and neck squamous cell carcinoma.

Pediatric Cholestatic Diseases: Common and Unique Pathogenic Mechanisms

Cholestasis is the predominate feature of many pediatric hepatobiliary diseases. The physiologic flow of bile requires multiple complex processes working in concert. Bile acid (BA) synthesis and excretion, the formation and flow of bile, and the enterohepatic reuptake of BAs all function to maintain the circulation of BAs, a key molecule in lipid digestion, metabolic and cellular signaling, and, as discussed in the review, a crucial mediator in the pathogenesis of cholestasis. Disruption of one or several of these steps can result in the accumulation of toxic BAs in bile ducts and hepatocytes leading to inflammation, fibrosis, and, over time, biliary and hepatic cirrhosis. Biliary atresia, progressive familial intrahepatic cholestasis, primary sclerosing cholangitis, and Alagille syndrome are four of the most common pediatric cholestatic conditions. Through understanding the commonalities and differences in these diseases, the important cellular mechanistic underpinnings of cholestasis can be greater appreciated.

Human vascularized bile duct-on-a chip: a multi-cellular micro-physiological system for studying cholestatic liver disease

Exploring the pathogenesis of and developing therapies for cholestatic liver diseases such as primary sclerosing cholangitis (PSC) remains challenging, partly due to a paucity ofin vitromodels that capture the complex environments contributing to disease progression and partly due to difficulty in obtaining cholangiocytes. Here we report the development of a human vascularized bile duct-on-a-chip (VBDOC) that uses cholangiocyte organoids derived from normal bile duct tissue and human vascular endothelial cells to model bile ducts and blood vessels structurally and functionally in three dimensions. Cholangiocytes in the duct polarized, formed mature tight junctions and had permeability properties comparable to those measured inex vivosystems. The flow of blood and bile was modeled by perfusion of the cell-lined channels, and cholangiocytes and endothelial cells displayed differential responses to flow. We also showed that the device can be constructed with biliary organoids from cells isolated from both bile duct tissue and the bile of PSC patients. Cholangiocytes in the duct became more inflammatory under the stimulation of IL-17A, which induced peripheral blood mononuclear cells and differentiated Th17 cells to transmigrate across the vascular channel. In sum, this human VBDOC recapitulated the vascular-biliary interface structurally and functionally and represents a novel multicellular platform to study inflammatory and fibrotic cholestatic liver diseases.

Single-cell sequencing of a novel model of neonatal bile duct ligation in mice identifies macrophage heterogeneity in obstructive cholestasis

Macrophages (MΦ) play a role in neonatal etiologies of obstructive cholestasis, however, the role for precise MΦ subsets remains poorly defined. We developed a neonatal murine model of bile duct ligation (BDL) to characterize etiology-specific differences in neonatal cholestatic MΦ polarization. Neonatal BDL surgery was performed on female BALB/c mice at 10 days of life (DOL) with sham laparotomy as controls. Comparison was made to the Rhesus Rotavirus (RRV)-induced murine model of biliary atresia (BA). Evaluation of changes at day 7 after surgery (BDL and sham groups) and murine BA (DOL14) included laboratory data, histology (H&E, anti-CD45 and anti-CK19 staining), flow cytometry of MΦ subsets by MHCII and Ly6c expression, and single cell RNA-sequencing (scRNA-seq) analysis. Neonatal BDL achieved a 90% survival rate; mice had elevated bile acids, bilirubin, and alanine aminotransferase (ALT) versus controls (p < 0.05 for all). Histology demonstrated hepatocellular injury, CD45+ portal infiltrate, and CK19+ bile duct proliferation in neonatal BDL. Comparison to murine BA showed increased ALT in neonatal BDL despite no difference in histology Ishak score. Neonatal BDL had significantly lower MHCII-Ly6c+ MΦ versus murine BA, however, scRNA-seq identified greater etiology-specific MΦ heterogeneity with increased endocytosis in neonatal BDL MΦ versus cellular killing in murine BA MΦ. We generated an innovative murine model of neonatal obstructive cholestasis with low mortality. This model enabled comparison to murine BA to define etiology-specific cholestatic MΦ function. Further comparisons to human data may enable development of immune modulatory therapies to improve patient outcomes.

Advances in understanding of biliary atresia pathogenesis and progression - a riddle wrapped in a mystery inside an enigma

INTRODUCTION

Biliary atresia is a potentially fatal condition of the bile ducts - both intra- and extrahepatic, for which we have no cure. Though principally a cholestatic condition, much of its pathology stems from its tendency to aggressively induce liver fibrosis and ultimately cirrhosis, only partially restrained by the portoenterostomy.

AREAS COVERED

This review is based on the current literature exploring the heterogeneous nature of biliary atresia. Thus, there are various phenotypes or variants of biliary atresia, each potentially with different etiological backgrounds caused by a number of hypothetical pathological mechanisms thought to be important in the genesis of the condition. Search methodology: the review (Oct. - Nov. 2022) is based on a search of PubMed (NLM) using main keyword 'biliary atresia' with supplementary searches using 'fibrosis'; 'inflammation'; 'BASM'; 'genetics'; 'surgery'; 'experimental'; 'etiology'; 'virology'; 'cases'; and 'syndromes.'

EXPERT OPINION

Future developments will be made on matching clinical variants with a more distinct pathophysiological discrimination and those pathways linking the initial cholestatic phase of biliary atresia to the early stages of fibrosis.

Necroptosis of macrophage is a key pathological feature in biliary atresia via GDCA/S1PR2/ZBP1/p-MLKL axis

Biliary atresia (BA) is a severe inflammatory and fibrosing neonatal cholangiopathy disease characterized by progressive obstruction of extrahepatic bile ducts, resulting in cholestasis and progressive hepatic failure. Cholestasis may play an important role in the inflammatory and fibrotic pathological processes, but its specific mechanism is still unclear. Necroptosis mediated by Z-DNA-binding protein 1 (ZBP1)/phosphorylated-mixed lineage kinase domain-like pseudokinase (p-MLKL) is a prominent pathogenic factor in inflammatory and fibrotic diseases, but its function in BA remains unclear. Here, we aim to determine the effect of macrophage necroptosis in the BA pathology, and to explore the specific molecular mechanism. We found that necroptosis existed in BA livers, which was occurred in liver macrophages. Furthermore, this process was mediated by ZBP1/p-MLKL, and the upregulated expression of ZBP1 in BA livers was correlated with liver fibrosis and prognosis. Similarly, in the bile duct ligation (BDL) induced mouse cholestatic liver injury model, macrophage necroptosis mediated by ZBP1/p-MLKL was also observed. In vitro, conjugated bile acid-glycodeoxycholate (GDCA) upregulated ZBP1 expression in mouse bone marrow-derived monocyte/macrophages (BMDMs) through sphingosine 1-phosphate receptor 2 (S1PR2), and the induction of ZBP1 was a prerequisite for the enhanced necroptosis. Finally, after selectively knocking down of macrophage S1pr2 in vivo, ZBP1/p-MLKL-mediated necroptosis was decreased, and further collagen deposition was markedly attenuated in BDL mice. Furthermore, macrophage Zbp1 or Mlkl specific knockdown also alleviated BDL-induced liver injury/fibrosis. In conclusion, GDCA/S1PR2/ZBP1/p-MLKL mediated macrophage necroptosis plays vital role in the pathogenesis of BA liver fibrosis, and targeting this process may represent a potential therapeutic strategy for BA.

Farnesoid X receptor antagonizes macrophage-dependent licensing of effector T lymphocytes and progression of sclerosing cholangitis

Immune-mediated bile duct epithelial injury and toxicity of retained hydrophobic bile acids drive disease progression in fibrosing cholangiopathies such as biliary atresia or primary sclerosing cholangitis. Emerging therapies include pharmacological agonists to farnesoid X receptor (FXR), the master regulator of hepatic synthesis, excretion, and intestinal reuptake of bile acids. Unraveling the mechanisms of action of pharmacological FXR agonists in the treatment of sclerosing cholangitis (SC), we found that intestinally restricted FXR activation effectively reduced bile acid pool size but did not improve the SC phenotype in MDR2-/- mice. In contrast, systemic FXR activation not only lowered bile acid synthesis but also suppressed proinflammatory cytokine production by liver-infiltrating inflammatory cells and blocked progression of hepatobiliary injury. The hepatoprotective activity was linked to suppressed production of IL1β and TNFα by hepatic macrophages and inhibition of TH1/TH17 lymphocyte polarization. Deletion of FXR in myeloid cells caused aberrant TH1 and TH17 lymphocyte responses in diethoxycarbonyl-1,4-dihydrocollidine-induced SC and rendered these mice resistant to the anti-inflammatory and liver protective effects of systemic FXR agonist treatment. Pharmacological FXR activation reduced IL1β and IFNγ production by liver- and blood-derived mononuclear cells from patients with fibrosing cholangiopathies. In conclusion, we demonstrate FXR to control the macrophage-TH1/17 axis, which is critically important for the progression of SC. Hepatic macrophages are cellular targets of systemic FXR agonist therapy for cholestatic liver disease.

Single-cell and spatial transcriptomics reveal the fibrosis-related immune landscape of biliary atresia

BACKGROUND

Biliary atresia (BA) is a devastating inflammatory and fibrosing cholangiopathy of neonates with unknown aetiology. We aim to investigate the relationship between these two main characteristics.

METHODS

Single-cell RNA sequencing and spatial transcriptomics were performed on liver samples from a cohort of 14 objects (BA: n = 6; control: n = 8). We conducted data integration and cell-type annotation based on gene expression profiling. Furthermore, we identified fibrosis-related immune cells according to their spatial locations, GO and KEGG analysis. Finally, SPOTlight and CIBERSORTx were used to deconvolute ST data and microarray data of the GSE46960 cohorts, respectively.

RESULTS

Immune subpopulations inhabiting the 'fibrotic niche' (areas of scarring), comprising 'intermediate' CD14⁺⁺ CD16⁺ monocytes, scar-associated macrophages, natural killer T cells, transitional B cells and FCN3⁺ neutrophils were identified. GO and KEGG analyses showed that pathways including 'positive regulation of smooth muscle cell/fibroblast proliferation' and 'positive regulation of/response to VEGFR/VEGF/EGFR/FGF' were enriched in these cell types. Interactions analysis showed that communication among 'FGF_FGFR', 'RPS19-C5AR1', 'CD74_COPA/MIF/APP' and 'TNFRSF1A/B_GRN' was extensive. Finally, the results of deconvolution for ST data and microarray data validated that the proportions of certain identified fibrosis-related cell types we identified were increased in BA.

DISCUSSION

Fibrosis is an important feature of BA, in which the immune system plays an important role. Our work reveals the subpopulations of immune cells enriched in the fibrotic niche of BA liver, as well as key related pathways and molecules; some are highlighted for the first time in liver fibrosis. These newly identified interactions might partly explain why the rate of liver fibrosis occurs much faster in BA than in other liver diseases.

CONCLUSION

Our study revealed the molecular, cellular and spatial immune microenvironment of the fibrotic niche of BA.

Immune cell C/EBPβ deficiency is associated with hepatic mononuclear defects and spontaneous hepatitis but not steatohepatitis induced liver fibrosis

BACKGROUND

CCAAT/enhancer-binding protein β (C/EBPβ) is a transcription factor known to be involved in macrophage differentiation and function, steatohepatitis and liver fibrosis.

METHODS

Immune restricted C/EBPβ deficient and control mice were investigated in steady-state and in the CDA-HFD steatohepatitis model. Mice were assessed for weight change, liver biochemical profile, histology and hepatic phagocytes composition.

RESULTS

Flow cytometry analysis of hepatic nonparenchymal cells revealed reduced numbers of hepatic monocytes and Kupffer cells and an increase in hepatic MHC class II positive myeloid cells in immune cells restricted C/EBPβ deficient mice. Immune-restricted C/EBPβ deficiency resulted in decreased weight gain and appearance of mild spontaneous liver inflammation. Nevertheless, In the CDA-HFD steatohepatitis model, immune restricted C/EBPβ deficient and proficient mice exhibit similar grade of hepatic steatosis, liver enzymes levels and fibrosis stage.

CONCLUSIONS

Immune-restricted C/EBPβ deficiency leads to significant alteration in hepatic mononuclear phagocytes composition associated with spontaneous mild hepatitis. Steatohepatitis associated fibrosis is not dependent on C/EBPβ expression by immune cells.

The Role of Vitamin D and Vitamin D Binding Protein in Chronic Liver Diseases

Vitamin D (calciferol) is a fat-soluble vitamin that has a significant role in phospho-calcium metabolism, maintaining normal calcium levels and bone health development. The most important compounds of vitamin D are cholecalciferol (vitamin D3, or VD3) and ergocalciferol (vitamin D2, or VD2). Besides its major role in maintaining an adequate level of calcium and phosphate concentrations, vitamin D is involved in cell growth and differentiation and immune function. Recently, the association between vitamin D deficiency and the progression of fibrosis in chronic liver disease (CLD) was confirmed, given the hepatic activation process and high prevalence of vitamin D deficiency in these diseases. There are reports of vitamin D deficiency in CLD regardless of the etiology (chronic viral hepatitis, alcoholic cirrhosis, non-alcoholic fatty liver disease, primary biliary cirrhosis, or autoimmune hepatitis). Vitamin D binding protein (VDBP) is synthesized by the liver and has the role of binding and transporting vitamin D and its metabolites to the target organs. VDBP also plays an important role in inflammatory response secondary to tissue damage, being involved in the degradation of actin. As intense research during the last decades revealed the possible role of vitamin D in liver diseases, a deeper understanding of the vitamin D, vitamin D receptors (VDRs), and VDBP involvement in liver inflammation and fibrogenesis could represent the basis for the development of new strategies for diagnosis, prognosis, and treatment of liver diseases. This narrative review presents an overview of the evidence of the role of vitamin D and VDBP in CLD, both at the experimental and clinical levels.

Reduced peroxisome proliferator-activated receptor-α and bile acid nuclear receptor NR1H4/FXR may affect the hepatic immune microenvironment of biliary atresia

Background

Biliary atresia (BA) is a childhood liver disease characterized by fibrous obstruction and obstruction of the extrahepatic biliary system and is one of the most common and serious biliary disorders in infants. Significant inflammation and fibrosis of the liver and biliary tract are the most prominent features, regardless of the initial damage to the BA. Abnormalities in innate or adaptive immunity have been found in human patients and mouse models of BA. We previously reported that children with BA had abnormal lipid metabolism, including free serum carnitine.

Objective

To study gene and protein expression levels of the hepatic peroxisome proliferator-activated receptor-α (PPARα) signaling pathway and farnesoid X receptor (FXR) in BA and BA fibrosis, and assess their clinical values.

Methods

Low expression of PPARα and NR1H4 (FXR) in BA were validated in the Gene Expression Omnibus database. Functional differences were determined by gene set enrichment analysis based on of PPARα and NR1H4 expression. BA patients from GSE46960 were divided into two clusters by using consensus clustering according to PPARα, NR1H4, and SMAD3 expression levels, and immunoinfiltration analysis was performed. Finally, 58 cases treated in our hospital were used for experimental verification. (IHC: 10 Biliary atresia, 10 choledochal cysts; PCR: 10 Biliary atresia, 14 choledochal cysts; WB: 10 Biliary atresia, 4 choledochal cysts).

Results

Bioinformatics analysis showed that the expression of PPARα, CYP7A1 and NR1H4 (FXR) in the biliary atresia group was significantly lower than in the control group. More BA-specific pathways, including TGFβ signaling pathway, P53 signaling pathway, PI3K-AKT-mTOR signaling pathway, etc., are enriched in BA patients with low PPARα and NR1H4 expression. In addition, low NR1H4 expression is abundant in inflammatory responses, IL6/STAT3 signaling pathways, early estrogen responses, IL2 STAT5 signaling pathways, and TGFβ signaling pathways. The TGFβ signaling pathway was significant in both groups. According to the expression of PPARα, NR1H4 and SMAD3, a key node in TGFβ pathway, BA patients were divided into two clusters using consensus clustering. In cluster 2, SMAD3 expression was high, and PPARα and NR1H4 expression were low. In contrast to cluster 1, immune cell infiltration was higher in cluster 2, which was confirmed by immunohistochemistry. The mRNA and protein levels of PPARα and NR1H4 in BA patients were lower than in the control group by immunohistochemistry, Western blot analysis and real-time PCR.

Conclusions

The downregulation of PPARα and NR1H4 (FXR) signaling pathway may be closely related to biliary atresia.

Biliary Atresia in Children: Update on Disease Mechanism, Therapies, and Patient Outcomes

Biliary atresia is a rare disease but remains the most common indication for pediatric liver transplantation as there are no effective medical therapies to slow progression after diagnosis. Variable contribution of genetic, immune, and environmental factors contributes to disease heterogeneity among patients with biliary atresia. Developing a deeper understanding of the disease mechanism will help to develop targeted medical therapies and improve patient outcomes.

Study protocol of Phase 2 open-label multicenter randomized controlled trial for granulocyte-colony stimulating factor (GCSF) in post-Kasai Type 3 biliary atresia

Animal studies support RCT findings of improved liver function and short-term benefits using repurposed Granulocyte Colonic Stimulating Factor GCSF in adults with decompensated cirrhosis. We describe the protocol for phase 2 RCT of sequential Kasai-GCSF under an FDA-approved IND to test that GCSF improves early bile flow and post-Kasai biliary atresia BA clinical outcome. Immediate post-Kasai neonates, age 15-180 days, with biopsy-confirmed type 3 BA, without access to early liver transplantation, will be randomized 1:1 to standard of care SOC + GCSF at 10 ug/kg in 3 daily doses within 4 days of Kasai vs SOC + NO-GCSF (ClinicalTrials.gov NCT0437391). They will be recruited from children's hospitals in Vietnam, Pakistan and one US center. The primary objective is to demonstrate that GCSF decreases the proportion of subjects with a 3-month post-Kasai serum Total Bilirubin ≥ 34 umol/L by 20%, (for a = 0.05, b = 0.80, i.e., calculated sample size of 218 subjects). The secondary objectives are to demonstrate that the frequency of post-Kasai cholangitis at 6-month and 24-month transplant-free survival are improved. The benefits are that GCSF is an affordable BA adjunct therapy, especially in developing countries, to improve biliary complications, enhance quality of liver and survival while diminishing costly liver transplantation.Clinical trial registration: A phase 1 for GCSF dose and safety determination under ClinicalTrials.gov identifier NCT03395028 was completed in 2019. The current Phase 2 trial was registered under NCT04373941.

Portal plate bile duct diameter in biliary atresia is associated with long-term outcome

PURPOSE

Kasai portoenterostomy (KPE) is the only treatment currently available for biliary atresia (BA). Age at KPE and surgical experience are prognostic factors for a successful KPE. Here, we aimed to assess whether the size of bile ductules at the porta hepatis during KPE correlates with KPE success and transplant-free survival (TFS).

METHODS

A retrospective analysis of patients diagnosed with BA during 2000-2019. Porta hepatis biopsies were reviewed for diameters of five representative ducts, and a mean ductal diameter (MDD) was calculated. Laboratory values including pre- and postoperative bilirubin levels were analyzed.

RESULTS

The cohort included 77 patients; for 33, ductal plate biopsy was available. KPE was successful in six of eight patients with MDD ≥ 50 µm, and in five of 25 with MDD < 50 µm, p = 0.008, OR = 12.0 (95% CI 1.83-78.3). Ten-year survival with native liver was higher in patients with MDD ≥ 50 µm than in patients with MDD < 50 µm, p < 0.001, HR 0.038 (95% CI 0.007-0.207). Direct bilirubin < 1 mg/dl 3 months post-KPE was associated with improved 2-year post-KPE TFS (27.7% vs. 13.9%, p < 0.0001).

CONCLUSIONS

MDD ≥ 50 µm correlates with KPE success and a higher rate of TFS. Direct bilirubin < 1 mg/dl 3 months post-operation may serve as a marker of successful biliary excretion, and a predictor of 2-year TFS.

Update on Etiology and Pathogenesis of Biliary Atresia

Biliary atresia is a rare inflammatory sclerosing obstructive cholangiopathy that initiates in infancy as complete choledochal blockage and progresses to the involvement of intrahepatic biliary epithelium. Growing evidence shows that biliary atresia is not a single entity with a single etiology but a phenotype resulting from multifactorial events whose common path is obliterative cholangiopathy. The etiology of biliary atresia has been explained as resulting from genetic variants, toxins, viral infection, chronic inflammation or bile duct lesions mediated by autoimmunity, abnormalities in the development of the bile ducts, and defects in embryogenesis, abnormal fetal or prenatal circulation and susceptibility factors. It is increasingly evident that the genetic and epigenetic predisposition combined with the environmental factors to which the mother is exposed are potential triggers for biliary atresia. There is also an indication that a progressive thickening of the arterial middle layer occurs in this disease, suggestive of vascular remodeling and disappearance of the interlobular bile ducts. It is suggested that the hypoxia/ischemia process can affect portal structures in biliary atresia and is associated with both the extent of biliary proliferation and the thickening of the medial layer.

Immune Characteristics in Biliary Atresia Based on Immune Genes and Immune Cell Infiltration

BACKGROUND

Biliary atresia (BA) is a serious biliary disease in infancy. Jaundice is the most visual and prominent symptom, and it mainly involves bile duct cells leading to the loss of intrahepatic and extrahepatic bile ducts. If left untreated, it will eventually progress to liver cirrhosis. The pathogenesis of BA is not clear, and it is now generally accepted that BA is an autoimmune disease. However, few studies have revealed the infiltration of immune cells in the liver of BA from a global perspective. We used liver tissue sequencing data to predict the infiltration and relative content of immune cells in BA.

METHODS

The BA datasets GSE46960, GSE15235, and GSE84044, and patient information were downloaded from the Gene Expression Omnibus (GEO) database. After batch normalization, the differentially expressed immune genes (DE-IGs) in BA liver, normal liver, and hepatitis B liver were analyzed with the cut-off value of |log₂fold change (log₂FC)| >1 and false discovery rate (FDR) <0.05. CIBERSORT software was used to predict the proportions of 22 immune cells in all samples of the datasets.

RESULTS

73 DE-IGs have been screened out between BA and normal tissue; among them, 20 genes were highly expressed and another 53 were expressed at a low level. A total of 30 DE-IGs existed between inflammation and fibrosis livers of BA, and all of them were expressed at low levels in fibrosis livers of BA. In GO term analysis, these DE-IGs were mainly associated with the MHC protein complex, cytokine, chemokine activity, and MHC-II receptor activity. In KEGG pathway analysis, the DE-IGs were mainly enriched in pathways of Th1 and Th2 cell differentiation, Th17 cell differentiation, IL-17 signaling pathway, Toll-like receptor signaling pathway, TNF signaling pathway, and autoimmune diseases. There were significant differences in immune infiltration among different pathological types of BA, and there were also obvious differences in immune infiltration of hepatitis B as a disease control of BA.

CONCLUSION

Based on immune genes and immune cell infiltration, this study reveals the immune characteristics of BA from a global point of view, which provides a new perspective for understanding the pathogenesis of BA and provides a direction for the diagnosis and treatment of BA.

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."

Effect and mechanism of vitamin D activation disorder on liver fibrosis in biliary atresia

To investigate the mechanism of 25 hydroxyvitamin D (25(OH)D) deficiency in children with biliary atresia (BA) and its effect on liver fibrosis. The serum vitamin D and 25(OH)D, and expression of 25 hydroxylase (CYP2R1 and CYP27A1) in the liver of BA patients were detected and compared with those in the control group. We investigated the effect of differential expression of CYP2R1 in hepatocytes on the expression of genes related to liver fibrosis in primary hepatic stellate cells (HSCs) of BA and animal models of cholestasis. The ratio of 25(OH)D/vitamin D in the BA group was significantly lower than that in the control group. The mRNA and protein expression of CYP2R1 and CYP27A1 in liver tissue of the BA group was significantly lower than that in the control group. Exogenous active vitamin D (calcitriol) inhibited the proliferation and migration of primary HSCs isolated from BA patients, and reduced the expression of fibrosis-related genes in vitro. Downregulation of expression of CYP2R1 in hepatocytes increased expression of transforming growth factor (TGF)-β1, collagen (Col)-1α1 and tissue inhibitor of metalloproteinase (TIMP)-1, and decreased the expression of matrix metalloproteinase (MMP)-2 in cocultured primary HSCs of BA. Upregulation of expression of CYP2R1 in mice with bile duct ligation significantly increased the level of 25(OH)D, decreased the expression of TGF-β1, Col-1α1 and TIMP-1, and increased the expression of MMP-2. Children with BA have impaired vitamin D activation due to CYP2R1 deficiency. The dysactivation of vitamin D can promote the proliferation and activation of HSCs and participate in the development of hepatic fibrosis in BA.

Granulocyte-colony stimulating factor GCSF mobilizes hematopoietic stem cells in Kasai patients with biliary atresia in a phase 1 study and improves short term outcome

AIMS

In RCT of adults with decompensated cirrhosis, GCSF mobilizes hematopoietic stem cells HSC and improves short-term outcome. An FDA-IND for sequential Kasai-GCSF treatment in biliary atresia BA was approved. This phase 1 study examines GCSF safety in Kasai subjects. Preliminary short-term outcome was evaluated.

METHODS

GCSF (Neupogen) at 5 or 10 μg/kg (n = 3/group) was given in 3 daily doses starting on day 3 of Kasai surgery (NCT03395028). Serum CD34+ HSC cell counts, and 1-month of GCSF-related adverse events were monitored. The 6-months Phase 1 clinical outcome was compared against 10 subsequent post Phase 1 Kasai patients who did not receive GCSF.

RESULTS

With GCSF, WBC and platelet count transiently increased, LFT and serum creatinine remained stable. Reversible splenic enlargement (by 8.5-20%) occurred in 5/6 subjects. HSC count increased 12-fold and 17.5-fold for the 5 μg/kg and10 ug/kg dose respectively; with respective median total bilirubin levels for GCSF vs no-GCSF groups of 55 vs 91 μM at 1 month, p = 0.05; 15 vs 37 μM at 3 months, p = 0.24); and the 6-months cholangitis frequency of 40% vs 90%, p = 0.077.

CONCLUSIONS

GCSF safely mobilizes HSC in Kasai infants and may improve short-term biliary drainage and cholangitis. Phase 2 efficacy outcome of GCSF adjunct therapy for sequential Kasai and GCSF is pending.

Conditional depletion of macrophages ameliorates cholestatic liver injury and fibrosis via lncRNA-H19

Although macrophages are recognized as important players in the pathogenesis of chronic liver diseases, their roles in cholestatic liver fibrosis remain incompletely understood. We previously reported that long noncoding RNA-H19 (lncRNA-H19) contributes to cholangiocyte proliferation and cholestatic liver fibrosis of biliary atresia (BA). We here show that monocyte/macrophage CD11B mRNA levels are increased significantly in livers of BA patients and positively correlated with the progression of liver inflammation and fibrosis. The macrophages increasingly infiltrate and accumulate in the fibrotic niche and peribiliary areas in livers of BA patients. Selective depletion of macrophages using the transgenic CD11b-diphtheria toxin receptor (CD11b-DTR) mice halts bile duct ligation (BDL)-induced progression of liver damage and fibrosis. Meanwhile, macrophage depletion significantly reduces the BDL-induced hepatic lncRNA-H19. Overexpression of H19 in livers using adeno-associated virus serotype 9 (AAV9) counteracts the effects of macrophage depletion on liver fibrosis and cholangiocyte proliferation. Additionally, both H19 knockout (H19-/-) and conditional deletion of H19 in macrophage (H19ΔCD11B) significantly depress the macrophage polarization and recruitment. lncRNA-H19 overexpressed in THP-1 macrophages enhance expression of Rho-GTPase CDC42 and RhoA. In conclusions, selectively depletion of macrophages suppresses cholestatic liver injuries and fibrosis via the lncRNA-H19 and represents a potential therapeutic strategy for rapid liver fibrosis in BA patients.

The relative abundance of monocyte subsets determines susceptibility to perinatal hepatic inflammation

The devastating consequences of perinatal liver inflammation contribute to a pressing need to develop therapeutics for the diseases that underly this condition. Biliary atresia (BA) is a perinatal inflammatory disease of the liver that results in obliterative cholangiopathy and rapidly progresses to liver failure, requiring transplantation. The ability to develop targeted therapies requires an understanding of the immune mechanisms that mitigate perinatal liver inflammation. This article reviews our recent findings demonstrating that in a murine model of perinatal hepatic inflammation, Ly6c^Lo non-classical monocytes express a pro-reparative transcriptomic profile and that the relative abundance of Ly6c^Lo monocytes promotes resolution of perinatal liver inflammation, rendering neonatal pups resistant to disease. We also examine the lineage relationship between monocyte subsets, reviewing data that suggests classical monocytes are a precursor for non-classical monocytes, and the alternative possibility that separate progenitors exist for each subset. Although a precursor-product relationship between classical and non-classical monocytes might exist in certain environments, we argue that they may also arise from separate progenitors, which is evident by sustained Ly6c^Lo non-classical monocyte expansion when Ly6c^Hi monocytes are absent. An improved understanding of monocyte subsets and their developmental trajectories during perinatal hepatic inflammation will provide insight into how therapies directed at controlling monocyte function may help alleviate the devastating consequences of diseases like BA.

Inflammation Drives MicroRNAs to Limit Hepatocyte Bile Acid Transport in Murine Biliary Atresia

BACKGROUND

Biliary atresia (BA) is an inflammatory pediatric cholangiopathy with only surgical means for treatment. Many contributors to bile acid synthesis and transport have previously been reported to be downregulated in patients with BA; yet, the driving factors of the abnormal bile acid synthesis and transport in regard to BA have not been previously studied.

MATERIALS AND METHODS

Wild type or Ig-α^-/- mice were injected with salt solution (control) or rotavirus on day of life 0, and analyses were performed on day of life 14. The mRNA levels of bile acid transporters/nuclear receptors and liver microRNAs (miRNAs) were compared between groups. A mouse hepatocyte cell line was used to examine the effects of innate cytokines on miRNA levels and bile acid transporter/nuclear receptor expression and miRNAs on bile acid transporter/nuclear receptor expression.

RESULTS

BA mice had significantly increased mRNA expression of innate cytokines and miRNAs known to bind bile acid transporters/nuclear receptors (miRNAs -22-5p, -34a-5p, and -222-3p) and decreased mRNA expression of bile acid transporters and nuclear receptors. In vitro, TNF-α and IL-1β decreased BSEP and CYP7A1 while increasing miRNA-34a-5p and miRNA 222-3p. LXR, SHP, CYP7A1, NTCP, and MRP2 were decreased by miRNA-34a-5p, whereas miRNA-222-3p decreased NTCP and MRP4. TNF-α and IL-1β increased expression of miRNAs 34a-5p and 222-3p and these miRNAs then decrease expression of multiple bile acid transporters and nuclear receptors.

CONCLUSIONS

Loss of bile acid transporters increases hepatotoxicity via bile acid retention. Therapeutic agents that increase bile acid transport or nuclear receptor functioning should be investigated in BA.

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.

Ly6cLo non-classical monocytes promote resolution of rhesus rotavirus-mediated perinatal hepatic inflammation

Perinatal hepatic inflammation can have devastating consequences. Monocytes play an important role in the initiation and resolution of inflammation, and their diverse functions can be attributed to specific cellular subsets: pro-inflammatory or classical monocytes (Ly6c^Hi) and pro-reparative or non-classical monocytes (Ly6c^Lo). We hypothesized that inherent differences in Ly6c^Hi classical monocytes and Ly6c^Lo non-classical monocytes determine susceptibility to perinatal hepatic inflammation in late gestation fetuses and neonates. We found an anti-inflammatory transcriptional profile expressed by Ly6c^Lo non-classical monocytes, and a physiologic abundance of these cells in the late gestation fetal liver. Unlike neonatal pups, late gestation fetuses proved to be resistant to rhesus rotavirus (RRV) mediated liver inflammation. Furthermore, neonatal pups were rendered resistant to RRV-mediated liver injury when Ly6c^Lo non-classical monocytes were expanded. Pharmacologic inhibition of Ly6c^Lo non-classical monocytes in this setting restored susceptibility to RRV-mediated disease. These data demonstrate that Ly6c^Lo monocytes promote resolution of perinatal liver inflammation in the late gestation fetus, where there is a physiologic expansion of non-classical monocytes, and in the neonatal liver upon experimental expansion of these cells. Therapeutic strategies directed towards enhancing Ly6c^Lo non-classical monocyte function may mitigate the detrimental effects of perinatal liver inflammation.

Innate Immunity and Pathogenesis of Biliary Atresia

Biliary atresia (BA) is a devastating fibro-inflammatory disease characterized by the obstruction of extrahepatic and intrahepatic bile ducts in infants that can have fatal consequences, when not treated in a timely manner. It is the most common indication of pediatric liver transplantation worldwide and the development of new therapies, to alleviate the need of surgical intervention, has been hindered due to its complexity and lack of understanding of the disease pathogenesis. For that reason, significant efforts have been made toward the development of experimental models and strategies to understand the etiology and disease mechanisms and to identify novel therapeutic targets. The only characterized model of BA, using a Rhesus Rotavirus Type A infection of newborn BALB/c mice, has enabled the identification of key cellular and molecular targets involved in epithelial injury and duct obstruction. However, the establishment of an unleashed chronic inflammation followed by a progressive pathological wound healing process remains poorly understood. Like T cells, macrophages can adopt different functional programs [pro-inflammatory (M1) and resolutive (M2) macrophages] and influence the surrounding cytokine environment and the cell response to injury. In this review, we provide an overview of the immunopathogenesis of BA, discuss the implication of innate immunity in the disease pathogenesis and highlight their suitability as therapeutic targets.

Bidirectional Cross-Talk between Biliary Epithelium and Th17 Cells Promotes Local Th17 Expansion and Bile Duct Proliferation in Biliary Liver Diseases

There is no effective treatment for autoimmune biliary diseases. Therefore, understanding their immunopathology is crucial. The biliary epithelial cells (BEC), expressing TLR-4, are constantly exposed to gut microbes and bacterial wall LPS, and in settings of inflammation, the immune infiltrate is dense within the peribiliary region of human liver. By dual immunohistochemistry, we affirm human intrahepatic T cell infiltrate includes CCR6+CD4+ and AhR+CD4+ T cells with potential for plasticity to Th17 phenotype. Mechanistically, we demonstrate that Th1 and Th17 inflammatory cytokines and LPS enhance human primary BEC release of the CCR6 ligand CCL20 and BEC secretion of Th17-polarizing cytokines IL-6 and IL-1β. Cell culture assays with human BEC secretome showed that secretome polarizes CD4 T cells toward a Th17 phenotype and supports the survival of Th17 cells. BEC secretome did not promote Th1 cell generation. Additionally, we give evidence for a mutually beneficial feedback of the type 17 cell infiltrate on BEC, showing that treatment with type 17 cytokines increases BEC proliferation, as monitored by Ki67 and activation of JAK2-STAT3 signaling. This study identifies human BEC as active players in determining the nature of the intrahepatic immune microenvironment. In settings of inflammation and/or infection, biliary epithelium establishes a prominent peribiliary type 17 infiltrate via recruitment and retention and enhances polarization of intrahepatic CD4 cells toward Th17 cells via type 17 cytokines, and, reciprocally, Th17 cells promote BEC proliferation for biliary regeneration. Altogether, we provide new insight into cross-talk between Th17 lymphocytes and human primary biliary epithelium in biliary regenerative pathologies.

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 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.

Recent advances in understanding biliary atresia

Biliary atresia (BA) is a neonatal liver disease characterized by progressive obstruction and fibrosis of the extrahepatic biliary tree as well as fibrosis and inflammation of the liver parenchyma. Recent studies found that infants who will go on to develop BA have elevated direct bilirubin levels in the first few days of life, suggesting that the disease starts in utero. The etiology and pathogenesis of BA, however, remain unknown. Here, we discuss recent studies examining potential pathogenetic mechanisms of BA, including genetic susceptibility, involvement of the immune system, and environmental insults such as viruses and toxins, although it is possible that there is not a single etiological agent but rather a large group of injurious insults that result in a final common pathway of extrahepatic bile duct obstruction and liver fibrosis. The management and diagnosis of BA have not advanced significantly in the past decade, but given recent advances in understanding the timing and potential pathogenesis of BA, we are hopeful that the next decade will bring early diagnostics and novel therapeutics.

Th17-associated cytokines multiplex testing indicates the potential of macrophage inflammatory protein-3 alpha in the diagnosis of biliary atresia

BACKGROUND & AIMS

Biliary atresia (BA) is a neonatal obliterative cholangiopathy with high prevalence in south China. Accurate identification of BA among infants with obstructive jaundice is still difficult by noninvasive diagnostic tools. Th17 cells have been reported closely related with the development of BA, which suggest that Th17-associated cytokines were potential biomarkers for the diagnosis of BA patients.

METHODS

In the training study, 76 infants who were divided into 2 groups, including BA group (n = 31) and non-BA jaundice group (n = 45). Clinical and routine laboratory data were collected from all subjects. Totally 25 Th17-associated cytokines were tested and compared between groups. The diagnostic value of each differential cytokine was evaluated by the area under the receiver operating characteristic curve (AUC). The best potential diagnostic biomarker was further validated in a cohort including 68 jaundice infants from our partnering institution in a blinded fashion.

RESULTS

Data from the training study showed that gamma-glutamyl transferase (GGT) and clay stool would be helpful in the identification of BA patients in jaundice subjects. Th17-associated cytokines assay indicated that IL-17F, IL-10, macrophage inflammatory protein-3alpha (MIP3a), IL-22, IL-13, IL-33, IL-6, IL-17E, IL-27, IL-31, TNF-a and TNF-b were differentially expressed in BA patients, and the AUC of MIP3a was higher than other markers. MIP3a alone or combined with other laboratory data would significantly increase the diagnostic accuracy of BA. The diagnostic value of MIP3a was further confirmed in our validation study.

CONCLUSION

MIP3a alone or combined with other laboratory data would significantly increase the diagnostic accuracy of BA.

Cytokine-Producing B Cells Promote Immune-Mediated Bile Duct Injury in Murine Biliary Atresia

Biliary atresia (BA) is a neonatal T cell-mediated, inflammatory, sclerosing cholangiopathy. In the rhesus rotavirus (RRV)-induced neonatal mouse model of BA (murine BA), mice lacking B cells do not develop BA, and the lack of B cells is associated with loss of T-cell and macrophage activation. The aim of this study was to determine the mechanism of B cell-mediated immune activation (antigen presentation versus cytokine production) in murine BA. Normal neonatal B cells in the liver are predominantly at pro-B and pre-B cellular development. However, BA mice exhibit a significant increase in the number and activation status of mature liver B cells. Adoptively transferred B cells into RRV-infected, B cell-deficient mice were able to reinstate T-cell and macrophage infiltration and biliary injury. Nonetheless, neonatal liver B cells were incompetent at antigen presentation to T cells. Moreover, 3-83 immunoglobulin transgenic mice, in which B cells only present an irrelevant antigen, developed BA, indicating a B-cell antigen-independent mechanism. B cells from BA mice produced a variety of innate and adaptive immune cytokines associated with immune activation. In vitro trans-well studies revealed that BA B cells secreted cytokines that activated T cells based on increased expression of T-cell activation marker cluster of differentiation 69. Conclusion: Neonatal liver B cells are highly activated in murine BA and contribute to immune activation through production of numerous cytokines involved in innate and adaptive immunity; this work provides increased knowledge on the capacity of neonatal B cells to contribute to an inflammatory disease through cytokine-mediated mechanisms, and future studies should focus on targeting B cells as a therapeutic intervention in human BA.

Interleukin 2 Promotes Hepatic Regulatory T Cell Responses and Protects From Biliary Fibrosis in Murine Sclerosing Cholangitis

In the multidrug resistance protein 2 (Mdr2)^-/- mouse model, low phospholipid bile instigates biliary epithelial injury, sterile inflammation, and fibrosis, thereby recapitulating disease mechanisms implicated in biliary atresia (BA) and primary sclerosing cholangitis. We hypothesize that T lymphocytes contribute to the biliary injury and fibrosis in murine sclerosing cholangitis (SC) and that they are susceptible to suppression by regulatory T cells (Tregs). In juvenile Mdr2^-/- mice, intrahepatic CD8+ lymphocytes were expanded, and contraction of intrahepatic Tregs coincided with rising serum alanine transferase and alkaline phosphatase (ALP) levels between days 14-30 of life. Antibody-mediated depletion of intrahepatic CD8+ lymphocytes during that time reduced ALP levels and the expression of osteopontin (Opn), a pro-fibrogenic cytokine. Depletion of intrahepatic Tregs with anti-CD25 antibody between days 7-30 increased intrahepatic CD8+ T cells, Opn expression, and fibrosis. Conversely, expansion of intrahepatic Tregs with interleukin 2/anti-interleukin 2 immune complexes (IL-2c) downregulated hepatic expression of Opn and Tnf, reduced frequency of intrahepatic CD8+ lymphocytes, and diminished biliary injury and fibrosis. Treatment with IL-2c upregulated hepatic Treg expression of CD39, an ectonucleotidase capable of hydrolyzing pro-inflammatory adenosine triphosphate. In vitro, Tregs expressing CD39 suppressed the proliferation of hepatic CD8+ lymphocytes from Mdr2^-/- mice more efficiently than those lacking CD39. In infants with BA, infiltration of interlobular bile ducts with CD8+ cells was associated with biliary expression of Opn and its transcription was negatively correlated with mRNA expression of Treg-associated genes. Conclusion: Hepatic CD8+ T lymphocytes drive biliary injury and fibrosis in murine SC. Their proliferation is controlled by hepatic Tregs through the purinergic pathway, which is responsive to IL-2c, suggesting that Treg-directed low-dose Il-2 treatment may be considered as therapy for SC.

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).

Myeloid Cells and Chronic Liver Disease: a Comprehensive Review

Myeloid cells play a major role in the sensitization to liver injury, particularly in chronic inflammatory liver diseases with a biliary or hepatocellular origin, and the interplay between myeloid cells and the liver may explain the increased incidence of hepatic osteodystrophy. The myeloid cell-liver axis involves several mature myeloid cells as well as immature or progenitor cells with the complexity of the liver immune microenvironment aggravating the mist of cell differentiation. The unique positioning of the liver at the junction of the peripheral and portal circulation systems underlines the interaction of myeloid cells and hepatic cells and leads to immune tolerance breakdown. We herein discuss the scenarios of different chronic liver diseases closely modulated by myeloid cells and illustrate the numerous potential targets, the understanding of which will ultimately steer the development of solid immunotherapeutic regimens. Ultimately, we are convinced that an adequate modulation of the liver microenvironment to modify the functional and quantitative characteristics of myeloid cells will be a successful approach to treating chronic liver diseases of different etiologies.

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.

Immunity and Fibrogenesis: The Role of Th17/IL-17 Axis in HBV and HCV-induced Chronic Hepatitis and Progression to Cirrhosis

Cirrhosis is a common final pathway for most chronic liver diseases; representing an increasing burden worldwide and is associated with increased morbidity and mortality. Current evidence has shown that, after an initial injury, the immune response has a significant participation in the ongoing damage, and progression from chronic viral hepatitis (CVH) to cirrhosis, driving the activation and maintenance of main fibrogenic pathways. Among immune deregulations, those related to the subtype 17 of T helper lymphocytes (Th17)/interleukin-17 (IL-17) axis have been recognized as key immunopathological and prognostic elements in patients with CVH. The Th17/IL-17 axis has been found involved in several points of fibrogenesis chain from the activation of stellate cells, increased expression of profibrotic factors as TGF-β, promotion of the myofibroblastic or epithelial–mesenchymal transition, stimulation of the synthesis of collagen, and induction of imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). It also promotes the recruitment of inflammatory cells and increases the expression of proinflammatory cytokines such as IL-6 and IL-23. So, the Th17/IL-17 axis is simultaneously the fuel and the flame of a sustained proinflammatory and profibrotic environment. This work aims to present the immunopathologic and prognostic role of the Th17/IL-17 axis and related pathways in fibrogenesis and progression to cirrhosis in patients with liver disease due to hepatitis B virus (HBV) and hepatitis C virus (HCV).

Hepatic MDR3 expression impacts lipid homeostasis and susceptibility to inflammatory bile duct obstruction in neonates

BackgroundHeterozygous mutations in the gene ABCB4, encoding the phospholipid floppase MDR3 (Mdr2 in mice), are associated with various chronic liver diseases. Here we hypothesize that reduced ABCB4 expression predisposes to extrahepatic biliary atresia (EHBA).MethodsLivers from neonatal wild-type (wt) and heterozygous Mdr2-deficient mice were subjected to mass spectrometry-based lipidomics and RNA sequencing studies. Following postnatal infection with rhesus rotavirus (RRV), liver immune responses and EHBA phenotype were assessed. Hepatic microarray data from 40 infants with EHBA were mined for expression levels of ABCB4.ResultsPhosphatidylcholine (PC) and phosphatidylethanolamine (PE) were increased, whereas the PC/PE ratio was decreased in neonatal Mdr2+/- mice compared with wt mice. Following RRV challenge, hepatic expression of IFNγ and infiltration with CD8+ and NK+ lymphocytes were increased in Mdr2+/- mice. Plasma total bilirubin levels and prevalence of complete ductal obstruction were higher in these mice. In infants with EHBA, hepatic gene expression of ABCB4 was downregulated in those with an inflammatory compared with a fibrosing molecular phenotype.ConclusionDecreased expression of ABCB4 causes dysregulation in (phospho)lipid homeostasis, and predisposes to aberrant pro-inflammatory lymphocyte responses and an aggravated phenotype of EHBA in neonatal mice. Downregulated ABCB4 is associated with an inflammatory transcriptome signature in infants with EHBA.