RARE DISEASE
Alagille syndrome
Alagille syndrome
Alagille syndrome
Synonyms: Alagille-Watson syndrome, Arteriohepatic dysplasia, Syndromic bile duct paucity
Synonyms: Alagille-Watson syndrome, Arteriohepatic dysplasia, Syndromic bile duct paucity
Synonyms: Alagille-Watson syndrome, Arteriohepatic dysplasia, Syndromic bile duct paucity
Drug discovery
6
drugs
With orphan designations
Overview
Alagille syndrome is a multisystem autosomal dominant disorder caused by JAG1 or NOTCH2 gene mutations, disrupting Notch signaling [2][10]. It primarily manifests as cholestasis due to bile duct paucity, with characteristic facial features, cardiac anomalies (e.g., pulmonic stenosis), and ocular/skeletal involvement [1][5][7]. Disease severity varies widely, ranging from asymptomatic carriers to life-threatening liver/cardiac complications [4][11].
Burden
Therapies
Medical: IBAT inhibitors (maralixibat/odevixibat) for pruritus [8][20], ursodiol, rifampin, antihistamines [12][16], and fat-soluble vitamin supplementation [3][14]
Surgical: Partial external biliary diversion for refractory pruritus; liver transplantation in 15-47% by adolescence [3][16]
Supportive: High-calorie diets, MCT-rich formulas, gastrostomy feeding for growth failure [3][16]
Categories: rare abdominal surgical diseases, rare cardiac malformations, rare developmental anomalies during embryogenesis, rare genetic diseases, rare hepatic diseases, rare neoplastic diseases, rare ophthalmic disorders, rare renal diseases, rare transplant-related disorders
Research Papers
321 drug discovery papers about Alagille syndrome, with 4 first-in-class and 4 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
321 drug discovery papers about Alagille syndrome, with 4 first-in-class and 4 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
proteins
2026-02-01 | Immune-mediated platelet dysfunction with spontaneous formation of aggregates in pediatric end-stage liver disease: A case report
Introduction A 12-year-old girl with Alagille syndrome was admitted with progressive liver failure and subsequently listed for liver transplantation. Furthermore, the patient was born with tetralogy of Fallot, for which corrective surgery was performed. Eleven years after surgery, a stent was implanted in the pulmonary artery due to progressive pulmonary stenosis. As expected in advanced hepatic insufficiency, she developed thrombocytopenia (baseline 100-120 Tsd/µl) and reduced vitamin K-dependent clotting factors. In May, platelet counts suddenly became immeasurable due to pronounced spontaneous platelet aggregation, fluctuating over time. Pseudothrombocytopenia was excluded. Light transmission aggregometry revealed absent aggregation in response to arachidonic acid and ristocetin 1mg/ml, consistent with a Bernard–Soulier- and Aspirin-like phenotype. Since the glycoprotein profile was normal, it appeared to be an acquired disorder, even though there was no solid evidence of any specific antibodies. In order to demonstrate the presumed antibodies indirectly, mixing studies were performed. When donor platelets were combined with the patient’s plasma, aggregation responses to ristocetin 1M and arachidonic acid improved, followed by gradual desaggregation. However, donor plasma combined with the patient’s platelets did not improve aggregation, suggesting that antibodies were primarily platelet-bound. Peripheral blood smears showed fragmented erythrocytes and complement activity was elevated, indicating microangiopathy. During pre-transplant evaluation, acquired von Willebrand syndrome was also diagnosed, as expected following stent angioplasty. Method Light transmission aggregometry Glycoprotein-specific ELISA Results Subsequent to liver transplantation, the patient was treated with von-Willebrand-Factor-containing factor VIII concentrate and regular platelet transfusions regardless of the absolute count. Tranexamic acid was avoided because of possible microangiopathy. Standard anticoagulation with unfractionated heparin was administered perioperatively. The liver transplantation proceeded without bleeding or thrombotic complications. Within one week after the last platelet transfusion, platelet count had normalized completely, and light transmission aggregometry confirmed full recovery of platelet function. Conclusion This case illustrates the complex coagulation abnormalities observed in end-stage liver disease, where hemostatic impairment may extend beyond reduced clotting factors to include Bernard–Soulier-like phenotype, and microangiopathy. Despite severe preoperative coagulopathy, precise perioperative management with targeted replacement therapy and cautious avoidance of prothrombotic agents enabled successful transplantation without bleeding events. Liver transplantation not only resolved hepatic failure but also led to rapid normalization of platelet counts and function, highlighting the reversible nature of these coagulation disorders once hepatic function is restored. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany
2024-01-31 | Spatially segregated defects and IGF1-responsiveness of hilar and peripheral biliary organoids from a model of Alagille syndrome.
Alagille syndrome (ALGS) manifests with peripheral intrahepatic bile duct (IHBD) paucity, which can spontaneously resolve. In a model for ALGS, Jag1Ndr/Ndr mice, this occurs with distinct architectural mechanisms in hilar and peripheral IHBDs. Here, we investigated region-specific IHBD characteristics and addressed whether IGF1, a cholangiocyte mitogen that is downregulated in ALGS and in Jag1Ndr/Ndr mice, can improve biliary outcomes. Intrahepatic cholangiocyte organoids (ICOs) were derived from hilar and peripheral adult Jag1+/+ and Jag1Ndr/Ndr livers (hICOs and pICOs, respectively). ICOs were grown in Matrigel or microwell arrays, and characterized using bulk RNA sequencing, immunofluorescence, and high throughput analyses of nuclear sizes. ICOs were treated with IGF1, followed by analyses of growth, proliferation, and death. CellProfiler and Python scripts were custom written for image analyses. Key results were validated in vivo by immunostaining. Cell growth assays and transcriptomics demonstrated that Jag1Ndr/Ndr ICOs were less proliferative than Jag1+/+ ICOs. IGF1 specifically rescued survival and growth of Jag1Ndr/Ndr pICOs. Jag1Ndr/Ndr hICOs were the least proliferative, with lower Notch signalling and an enrichment of hepatocyte signatures and IGF uptake/transport pathways. In vitro (Jag1Ndr/Ndr hICOs) and in vivo (Jag1Ndr/Ndr hilar portal tracts) analyses revealed ectopic HNF4a+ hepatocytes. Hilar and peripheral Jag1Ndr/Ndr ICOs exhibit differences in Notch signalling status, proliferation, and cholangiocyte commitment which may result in cholangiocyte-to-hepatocyte transdifferentiation. While Jag1Ndr/Ndr pICOs can be rescued by IGF1, hICOs are unresponsive, perhaps due to their hepatocyte-like state and/or expression of IGF transport components. IGF1 represents a potential therapeutic for peripheral bile ducts.
2022-03-30 | Role of Immune Cells in Biliary Repair
The biliary system is comprised of cholangiocytes and plays an important role in maintaining liver function. Under normal conditions, cholangiocytes remain in the stationary phase and maintain a very low turnover rate. However, the robust biliary repair is initiated in disease conditions, and different repair mechanisms can be activated depending on the pathological changes. During biliary disease, immune cells including monocytes, lymphocytes, neutrophils, and mast cells are recruited to the liver. The cellular interactions between cholangiocytes and these recruited immune cells as well as hepatic resident immune cells, including Kupffer cells, determine disease outcomes. However, the role of immune cells in the initiation, regulation, and suspension of biliary repair remains elusive. The cellular processes of cholangiocyte proliferation, progenitor cell differentiation, and hepatocyte-cholangiocyte transdifferentiation during biliary diseases are reviewed to manifest the underlying mechanism of biliary repair. Furthermore, the potential role of immune cells in crucial biliary repair mechanisms is highlighted. The mechanisms of biliary repair in immune-mediated cholangiopathies, inherited cholangiopathies, obstructive cholangiopathies, and cholangiocarcinoma are also summarized. Additionally, novel techniques that could clarify the underlying mechanisms of biliary repair are displayed. Collectively, this review aims to deepen the understanding of the mechanisms of biliary repair and contributes potential novel therapeutic methods for treating biliary diseases.
2021-05-10 | Transcriptional profiling of pediatric cholestatic livers identifies three distinct macrophage populations.
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. 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. 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. 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.
2015-03-30 | CCN1 induces hepatic ductular reaction through integrin αvβ5–mediated activation of NF-κB
Liver cholestatic diseases, which stem from diverse etiologies, result in liver toxicity and fibrosis and may progress to cirrhosis and liver failure. We show that CCN1 (also known as CYR61), a matricellular protein that dampens and resolves liver fibrosis, also mediates cholangiocyte proliferation and ductular reaction, which are repair responses to cholestatic injury. In cholangiocytes, CCN1 activated NF-κB through integrin αvβ5/αvβ3, leading to Jag1 expression, JAG1/NOTCH signaling, and cholangiocyte proliferation. CCN1 also induced Jag1 expression in hepatic stellate cells, whereupon they interacted with hepatic progenitor cells to promote their differentiation into cholangiocytes. Administration of CCN1 protein or soluble JAG1 induced cholangiocyte proliferation in mice, which was blocked by inhibitors of NF-κB or NOTCH signaling. Knock-in mice expressing a CCN1 mutant that is unable to bind αvβ5/αvβ3 were impaired in ductular reaction, leading to massive hepatic necrosis and mortality after bile duct ligation (BDL), whereas treatment of these mice with soluble JAG1 rescued ductular reaction and reduced hepatic necrosis and mortality. Blockade of integrin αvβ5/αvβ3, NF-κB, or NOTCH signaling in WT mice also resulted in defective ductular reaction after BDL. These findings demonstrate that CCN1 induces cholangiocyte proliferation and ductular reaction and identify CCN1/αvβ5/NF-κB/JAG1 as a critical axis for biliary injury repair.
cell therapies
2026-08-12 | Long-Term Outcomes of Living Donor Liver Transplantation in Children With Alagille Syndrome: Results From Vanguard Multicenter Study of International Living Donor Liver Transplantation Group.
The morbidity and mortality after living donor liver transplantation (LDLT) in children with Alagille syndrome (AGS) are complex because of the multisystem involvement of the disease. Evidence on long-term outcomes and donor selection remains limited. This multicenter retrospective study included 49 pediatric patients with AGS who underwent LDLT between 2001 and 2020 at eight institutions in Japan, Korea, and Turkey. Clinical characteristics, transplant indications, donor selection, posttransplant growth, renal function, and complications were analyzed. The median age at LDLT was 1.1 years. Major indications for transplantation were severe growth failure (91.8%) and advanced liver disease with hepatic dysfunction. Based on donor evaluations, 11% of candidates were excluded due to genetic or anatomical concerns. The 5-year patient and graft survival rates were 93.7% and 91.5%, respectively. LDLT before 2 years of age was associated with significantly greater catch-up in height and weight. Long-term renal deterioration was observed, particularly beyond 15 years after transplantation, and older age at LDLT was an independent predictor of lower long-term estimated glomerular filtration rate. Cardiac anomalies were manageable with appropriate preoperative evaluation, whereas vasculopathies were observed after adolescence. A history of Kasai portoenterostomy did not significantly affect posttransplant outcomes. LDLT provides excellent short- and long-term outcomes in pediatric AGS. Timely LT may improve growth and preserve renal function before progressive multisystem complications become established. Long-term surveillance and comprehensive donor evaluation remain essential.
2025-03-28 | Liver transplantation in children: pre-transplantation preparation tactics
Liver transplantation (LT) from a living related donor is the only life-saving option for children with congenital liver diseases such as biliary atresia, Alagille syndrome, progressive familial intrahepatic cholestasis, and Byler disease, as well as metabolic disorders and acute or chronic liver failure. The development of LT from living related donors significantly reduces the waiting time for a donor organ. The success of the procedure largely depends on the quality of pre-transplantation preparation (PTP) of both donor and recipient. Aim - to study the features of PTP in children with cholestatic liver diseases for successful LT. Materials and methods. 37 children with biliary atresia underwent PTP between 2005 and 2023. In 36 cases, LT was performed using a living related donor; in one case, split-liver transplantation (SPLIT-LT) was used. PTP lasted 3–6 months and included infection focus sanitation, correction of congenital anomalies, emergency status assessment, and evaluation of physical and psycho-emotional development. All examinations followed current international standards. Results. All transplantations were successful. After PTP, improvements were observed in hematological parameters, functional and neuropsychological development, and reduced anxiety levels. All transplant centers acknowledged the high quality of PTP; no child was refused transplantation due to inadequate preparation. The key readiness criteria were a compensated clinical state and a safe bacterial environment. Conclusions. Compliance with regulatory standards and protocols for PTP ensures successful pediatric LT and protects donor health. PTP improves hematological, somatic, and psycho-emotional indicators, reduces risks, and increases the effectiveness of transplantation. Our experience with PTP aligns with international standards. The research was carried out in accordance with the principles of the Declaration of Helsinki. Informed consent of the child and child's parents was obtained for the research. No conflict of interest was declared by the author.
2024-08-28 | Generation of human iPSC-derived 3D bile duct within liver organoid by incorporating human iPSC-derived blood vessel.
In fetal development, tissue interaction such as the interplay between blood vessel (BV) and epithelial tissue is crucial for organogenesis. Here we recapitulate the spatial arrangement between liver epithelial tissue and the portal vein to observe the formation of intrahepatic bile ducts (BDs) from human induced pluripotent stem cells (hiPSC). We co-culture hiPSC-liver progenitors on the artificial BV consisting of immature smooth muscle cells and endothelial cells, both derived from hiPSCs. After 3 weeks, liver progenitors within hiPSC-BV-incorporated liver organoids (BVLO) differentiate to cholangiocytes and acquire epithelial characteristics, including intercellular junctions, microvilli on the apical membrane, and secretory functions. Furthermore, liver surface transplanted-BVLO temporarily attenuates cholestatic injury symptoms. Single cell RNA sequence analysis suggests that BD interact with the BV in BVLO through TGFβ and Notch pathways. Knocking out JAG1 in hiPSC-BV significantly attenuates bile duct formation, highlighting BVLO potential as a model for Alagille syndrome, a congenital biliary disease. Overall, we develop a novel 3D co-culture method that successfully establishes functional human BDs by emulating liver epithelial-BV interaction.
2024-08-21 | Durability of Aortic Homografts in Pulmonary Atresia and Major Aortopulmonary Collateral Arteries.
Objectives: It is well-known that right ventricle-to-pulmonary artery homograft conduit durability is worse for smaller conduits and smaller/younger patients. However, there is limited literature on age and conduit-size specific outcomes, or on the role of conduit oversizing. Methods: Patients diagnosed with tetralogy of Fallot and major aortopulmonary collateral arteries undergoing right ventricular outflow tract (RVOT) reconstruction with a valved aortic homograft conduit from November 2001 through March 2023, at our institution were included. Conduits were grouped and evaluated by diameter, diameter Z-score, and patient age at implant. The primary time-related outcome was freedom from RVOT reintervention. Factors associated with freedom from time-related outcomes were assessed with univariable Cox regression analysis. Results: A total of 863 RVOT conduits were implanted in 722 patients. On multivariable analysis, younger age, male sex, Alagille syndrome, smaller diameter of the conduit, and smaller Z-score were associated with shorter freedom from reintervention. Among patients with smaller diameter conduits, larger Z-scores were associated with longer freedom from conduit reintervention (P < .001). Transcatheter interventions were commonly used to extend conduit lifespan across ages and conduit sizes. Conclusions: Larger conduit diameter, older age, and higher conduit Z-score were associated with longer freedom from reintervention in patients undergoing RVOT reconstruction in this cohort. Oversizing of conduits, even beyond a Z-score of 4, is generally appropriate.
2024-06-28 | Alagille syndrome in the clinical practice of a paediatric surgeon
Alagille syndrome (AGS) is one of the most problematic for the diagnosis of hereditary, multisystem, cholestatic liver diseases in combination with other congenital defects. Timely diagnosis and treatment (including liver transplantation - LT) improves the quality of life (QoL), prevents irreversible liver changes, multiple organ failure and mortality. Aim – to study the possibilities and features of the differential diagnosis of AGS, the impact of complex treatment, surgical correction (including LT) on the course of the disease, the dynamics of clinical and laboratory indicators, physical development (FD) and neuropsychological development (NPD), QoL. Materials and methods. Verification of the diagnosis of AGS included clinical, biochemical, instrumental examinations, genetic markers of AGS. Quality of life was evaluated: assessment of skin itching (on a categorical scale, according to the visual analogue scale of pruritus; the level of anxiety was determined according to the Hamilton scale (modified). FD and NPD were evaluated by pediatricians and pediatric neurologists before and after treatment. The assessment of FD according to centile tables was carried out in accordance with WHO standards. The assessment of NPD was carried out: development delay for one, two, three epicrisis terms; degree of NPD delay. Results. Against the background of treatment, biochemical and clinical indicators improved. Itching of the skin (according to the categorical scale of itching, visual analogue scale of pruritus), decreased the anxiety index. The dynamics of the FD and NPD were positive. Conclusions. Modern possibilities of diagnosis of AGS include genetic and histological methods, which makes it possible to start pathogenetic therapy early, to decide the time and ways of surgical intervention (including LT). The presence of concomitant congenital defects of other organs and systems, the characteristic appearance of children with AGS require a multidisciplinary examination with the involvement of multidisciplinary specialists. Complex and timely treatment of AGS contributes to the normalization of clinical and biochemical indicators, FD, NPD, quality of life. Radical treatment of AGS by means of LT should be considered before the period of irreversible multiorgan changes, taking into account the preservation of FD and NPD. The research was carried out in accordance with the principles of the Declaration of Helsinki. Informed consent of the child and child's parents was obtained for the research. The author declares no conflict of interest.
small molecules
2026-07-25 | Three high throughput compatible cell-based assays for identifying small molecule JAG1 upregulators for Alagille syndrome.
Haploinsufficiency disorders arise when loss of function mutations in one allele of a gene reduce gene dosage below the level required for normal physiology. Pharmacologic upregulation of the remaining functional allele represents a promising therapeutic strategy but requires screening assays capable of detecting modest changes in endogenous gene expression. Here we developed and compared three high throughput cell-based assays for identifying small molecule upregulators of JAG1, the gene most frequently mutated in Alagille syndrome (ALGS). The assays measure JAG1 expression at different molecular levels: RNA fluorescence in situ hybridization (RNA FISH) for JAG1 mRNA, immunofluorescence (IF) for endogenous JAG1 protein, and a HiBiT luminescence assay using CRISPR engineered LX-2 hepatic stellate cells expressing HiBiT tagged JAG1. Each assay was optimized in 384-well format and benchmarked using a panel of 32 histone deacetylase inhibitors (HDACi), compounds known to broadly increase gene expression. All three assays detected JAG1 upregulation and identified overlapping sets of active compounds. The homogeneous HiBiT assay showed the most favorable high throughput screening statistics (S/B = 2.7 and Z' > 0.5) and the lowest well to well variability, whereas the RNA FISH and IF assays provided higher signal to basal ratios and single cell resolution. Entinostat, Mocetinostat, and Chidamide were consistently identified as the most potent JAG1 upregulators across all assays. These complementary assays provide a flexible platform for identifying small molecule modulators of gene dosage and may be broadly applicable to drug discovery efforts targeting haploinsufficiency diseases.
2026-06-18 | Heterozygous variants in NOTCH2 in a cohort of juvenile and adult patients with cholestatic liver disease: Disease modifiers or innocent bystanders?
Background and objective: Genetic cholestatic liver diseases are increasingly stratified using NGS. The resulting information can guide treatment with novel drugs such as IBAT inhibitors, which have demonstrated efficacy in congenital liver disorders including Alagille syndrome and PFIC. We hypothesised [for full text, please go to the a.m. URL]
2026-06-18 | Use of genetic analysis in adult cholestatic liver disease: lessons from progressive paediatric syndromes and cohort studies.
The increasing availability and decreasing costs of DNA sequencing have resulted in the re-grouping of rare, severe paediatric cases of progressive familial intrahepatic cholestasis (PFIC) with more frequent, later-onset cases of cholestasis (eg, intrahepatic cholestasis of pregnancy, benign recurrent intrahepatic cholestasis, low phospholipid-associated cholelithiasis) under the umbrella of genetic cholestasis. The common denominator is the presence of functional variants in the PFIC-associated genes, predominantly in ABCB4, ABCB11 and ATP8B1, which cause PFIC types 1-3. Several other congenital diseases such as Alagille syndrome and alpha1-antitrypsin deficiency comprise cholestatic pruritus as frequent symptoms.With the availability of intestinal bile acid transporter inhibitors (IBATi) as new and efficacious therapeutics for pruritus, the most debilitating symptom of PFIC, it is essential to envision their usefulness for patients with later-onset cholestatic liver disease suffering from pruritus.In this review, we summarise published studies on the genetic makeup of patients with paediatric, juvenile and adult-onset cholestasis, and discuss their findings with respect to genotype-specific treatment with IBATi, ursodeoxycholic acid, or alternative drugs. The aim is to provide an overview of the genetic variants likely to be encountered in future sequencing investigations of patients with cholestatic liver diseases, and how to translate this genetic information into personalised treatment recommendations.
2026-04-28 | JAG1-independent Notch activation via Silymarin-mediated DLL4 upregulation
Silymarin from Silybum marianum enhances DLL4 (Delta-like ligand 4) expression in hepatocytes through NRF2-mediated transcriptional activation, providing alternative Notch signaling pathway activation to compensate for deficient JAG1-mediated signaling in Alagille syndrome
2026-03-25 | Notch signaling in liver diseases: mechanistic insights and therapeutic implications.
The Notch signaling pathway represents an evolutionarily conserved mechanism of intercellular communication that plays critical roles in organ development and tissue homeostasis. However, its functions in liver physiology and pathology demonstrate remarkable context-dependent characteristics, with dysregulated signaling contributing to various liver disorders. This review systematically summarizes the complex roles of Notch signaling in liver health and disease. It comprehensively examines the pathway's essential functions in biliary development, hepatic regeneration, and metabolic homeostasis, while providing a detailed analysis of its pathogenic mechanisms in conditions including Alagille syndrome, drug-induced liver injury, non-alcoholic fatty liver disease, liver fibrosis, hepatocellular carcinoma, and intrahepatic cholangiocarcinoma. Our review particularly emphasizes the dual function of Notch signaling in hepatobiliary malignancies, where it can exert either oncogenic or tumor-suppressive effects depending on specific cellular contexts, molecular interactions, and microenvironmental cues. Furthermore, we highlight the evolution of therapeutic strategies from broad-spectrum γ-secretase inhibitors to more precise approaches involving ligand-specific antibodies, transcriptional complex blockers, and pathway agonists, while addressing persistent challenges in clinical translation including on-target toxicities, compensatory resistance mechanisms, and context-dependent responses. Looking forward, this review outlines promising research directions featuring biomarker-guided patient stratification, rational combination therapies with immune checkpoint inhibitors, and spatiotemporally precise regulatory strategies. By integrating foundational knowledge with recent advances, this work provides valuable insights for understanding Notch signaling's complex roles in liver pathophysiology and for developing novel therapeutic interventions.
gene therapies
2026-05-04 | From supportive to targeted treatment strategies: the changing landscape of therapeutics in Alagille syndrome
1. Alagille syndrome (ALGS) is an autosomal dominant developmental disorder characterized by highly variable, multisystem involvement and caused by pathogenic variants in the genes Jagged1 (JAG1) a...
2025-10-19 | Pediatric Liver Diseases: Next-Generation Therapies.
With recent advances in molecular medicine, there has been a transformation of the landscape of pediatric liver disease therapeutics. The advent of gene editing technologies, RNA therapeutics, and molecular chaperone therapies has led to precise targeting of liver pathology. This review aims to shed light on recent breakthroughs in liver-directed nucleic acid therapies such as small interfering RNA, mRNA editing, and CRISPR-based approaches, with a special focus on their application in alpha-1 antitrypsin deficiency, hepatitis B, cystic fibrosis-related liver disease, metabolic dysfunction-associated steatotic liver disease, Alagille syndrome, progressive familial intrahepatic cholestasis, and acute hepatic porphyria.
2025-05-31 | Adeno-associated Virus-mediated Silencing of Sox4 Leads to Long-Term Amelioration of Liver Phenotypes in Mouse Models of Alagille Syndrome.
In patients with Alagille syndrome (ALGS), bile duct paucity often leads to severe cholestatic phenotypes for which liver transplantation remains the only definitive treatment. No Food and Drug Administration-approved mechanism-based strategies exist to enhance biliary development in ALGS or other diseases with bile duct paucity. We aimed to identify a therapeutic target to address this unmet need. Preclinical ALGS mouse models lacking 1 copy of Jag1 with or without conditional deletion of 1 or both copies of Sox9 were used. Sox4 levels were reduced genetically or with adeno-associated virus 8 (AAV8) vectors driving a Sox4-silencing sequence. Liver histology, biliary tree ink injection, serum chemistry, RNAscope (on mouse and human livers), mouse liver single-cell RNA-sequencing, and reanalysis of published human liver bulk RNA-sequencing were performed. Conditional removal of 1 copy of Sox4 in mouse liver significantly improved the ALGS liver phenotypes in a Sox9-dependent manner. An increase in Sox4/SOX4 expression in early postnatal Jag1-heterozygous mouse livers and ALGS patient livers was observed. single-cell RNA-sequencing revealed the appearance of an intermediate hepatobiliary cluster co-expressing Sox4 and Sox9 in Jag1-heterozygous livers. AAV8-mediated Sox4 knockdown, ubiquitously or driven by the hepatocyte-specific thyroxine-binding globulin promoter, led to long-term improvement of ALGS liver phenotypes upon injection at postnatal day 1. AAV8 injection at postnatal day 15-after the appearance of liver necrosis-led to the incorporation of some transduced cells into bile ducts and phenotypic improvement. Preclinical studies provide proof of principle for postnatal AAV-mediated Sox4 knockdown in thyroxine-binding globulin+ cells as a therapeutic approach for ALGS liver disease.
2021-04-14 | Sox9 Is a Modifier of the Liver Disease Severity in a Mouse Model of Alagille Syndrome.
Alagille syndrome (ALGS) is a multisystem developmental disorder characterized by bile duct (BD) paucity, caused primarily by haploinsufficiency of the Notch ligand jagged1. The course of the liver disease is highly variable in ALGS. However, the genetic basis for ALGS phenotypic variability is unknown. Previous studies have reported decreased expression of the transcription factor SOX9 (sex determining region Y-box 9) in late embryonic and neonatal livers of Jag1-deficient mice. Here, we investigated the effects of altering the Sox9 gene dosage on the severity of liver disease in an ALGS mouse model. Conditional removal of one copy of Sox9 in Jag1+/- livers impairs the biliary commitment of cholangiocytes and enhances the inflammatory reaction and liver fibrosis. Loss of both copies of Sox9 in Jag1+/- livers further worsens the phenotypes and results in partial lethality. Ink injection experiments reveal impaired biliary tree formation in the periphery of P30 Jag1+/- livers, which is improved by 5 months of age. Sox9 heterozygosity worsens the P30 biliary tree phenotype and impairs the partial recovery in 5-month-old animals. Notably, Sox9 overexpression improves BD paucity and liver phenotypes in Jag1+/- mice without ectopic hepatocyte-to-cholangiocyte transdifferentiation or long-term liver abnormalities. Notch2 expression in the liver is increased following Sox9 overexpression, and SOX9 binds the Notch2 regulatory region in the liver. Histological analysis shows a correlation between the level and pattern of SOX9 expression in the liver and outcome of the liver disease in patients with ALGS. Our results establish Sox9 as a dosage-sensitive modifier of Jag1+/- liver phenotypes with a permissive role in biliary development. Our data further suggest that liver-specific increase in SOX9 levels is a potential therapeutic approach for BD paucity in ALGS.
2015-11-30 | Alagille Syndrome Mimicking Biliary Atresia in Early Infancy
Alagille syndrome may mimic biliary atresia in early infancy. Since mutations in JAG1 typical for Alagille syndrome type 1 have also been found in biliary atresia, we aimed to identify JAG1 mutations in newborns with proven biliary atresia (n = 72). Five biliary atresia patients with cholestasis, one additional characteristic feature of Alagille syndrome and ambiguous liver histology were single heterozygotes for nonsense or frameshift mutations in JAG1. No mutations were found in the remaining 67 patients. All "biliary atresia" carriers of JAG1 null mutations developed typical Alagille syndrome at the age of three years. Our data do not support association of biliary atresia with JAG1 mutations, at least in Czech patients. Rapid testing for JAG1 mutations could prevent misdiagnosis of Alagille syndrome in early infancy and improve their outcome.
other
2025-09-22 | Antisense oligonucleotide-mediated upregulation of Jag1 ameliorates liver disease phenotypes in a mouse model of Alagille syndrome.
Alagille syndrome (ALGS) is a rare genetic disorder that affects multiple organ systems, especially the liver, leading to life-threatening complications. In most cases, ALGS is caused by haploinsufficient mutations in the JAG1 gene, resulting in impaired liver bile duct development during early childhood. Therefore, increasing JAG1 protein levels in ALGS patients offers a potential therapeutic approach. In this study, we designed antisense oligonucleotides (ASOs) targeting the JAG1 mRNA to enhance translation through different mechanisms. We found that certain ASOs targeting the upstream open reading frame (uORF) increased JAG1 protein levels in various cell lines and ALGS patient-derived cells. Optimized ASOs also increased Jag1 protein levels in normal mouse liver for up to 2-fold, accompanied by elevated levels of cleaved Notch1 protein, suggesting that the increased Jag1 protein was functionally active. Importantly, ASO treatment increased Jag1 protein in Jag1 +/- mouse model. When newborn Jag1 +/- mice were treated with ASO, improved bile duct development was observed, along with trends of reduced plasma bile acids, bilirubin, and triglyceride levels, implying improved liver function. Together, these results suggest that ASO-induced JAG1 upregulation may provide a promising therapeutic opportunity for ALGS patients, especially when treated at an early age.
2025-03-05 | Alagille Syndrome: Unraveling the Complexities of Genotype-Phenotype Relationships and Exploring Avenues for Improved Diagnosis and Treatment.
Alagille syndrome (ALGS) is a rare genetic disorder caused by mutations in the JAG1 and NOTCH2 genes, leading to a wide range of clinical manifestations. This review explores the complex genetic and clinical landscape of ALGS, emphasizing the challenges in understanding genotype-phenotype relationships due to its rarity and the lack of suitable research models. The review projects a clinical overview of the disease, emphasizing the influence of potential gene modifiers on its clinical presentation and the lack of mechanistic studies for over 100 mutations identified in the last 24 years from various populations, representing a significant gap in our current knowledge and advocating for further exploration. The review addresses the diagnostic challenges posed by the variable expressivity and overlapping symptoms of ALGS. It summarizes current treatment options and discusses emerging approaches such as antisense oligonucleotides (ASOs) and gene therapies. Further, the need for improved diagnostic tools, a deeper understanding of the underlying mechanisms, and the development of targeted therapies are emphasized using zebrafish and mice models, as well as genome editing for variant analysis and stem cell organoid models for disease modeling and drug discovery. The importance of cohort-based studies in understanding the natural history and outcomes of ALGS in diverse populations is highlighted. The review concludes by emphasizing the need for multi-disciplinary collaborative research to address the challenges in ALGS diagnosis, prognosis, and treatment, particularly for underrepresented populations.
2024-10-03 | Jag1 insufficiency alters liver fibrosis via T cell and hepatocyte differentiation defects.
Fibrosis contributes to tissue repair, but excessive fibrosis disrupts organ function. Alagille syndrome (ALGS, caused by mutations in JAGGED1) results in liver disease and characteristic fibrosis. Here, we show that Jag1Ndr/Ndr mice, a model for ALGS, recapitulate ALGS-like fibrosis. Single-cell RNA-seq and multi-color flow cytometry of the liver revealed immature hepatocytes and paradoxically low intrahepatic T cell infiltration despite cholestasis in Jag1Ndr/Ndr mice. Thymic and splenic regulatory T cells (Tregs) were enriched and Jag1Ndr/Ndr lymphocyte immune and fibrotic capacity was tested with adoptive transfer into Rag1-/- mice, challenged with dextran sulfate sodium (DSS) or bile duct ligation (BDL). Transplanted Jag1Ndr/Ndr lymphocytes were less inflammatory with fewer activated T cells than Jag1+/+ lymphocytes in response to DSS. Cholestasis induced by BDL in Rag1-/- mice with Jag1Ndr/Ndr lymphocytes resulted in periportal Treg accumulation and three-fold less periportal fibrosis than in Rag1-/- mice with Jag1+/+ lymphocytes. Finally, the Jag1Ndr/Ndr hepatocyte expression profile and Treg overrepresentation were corroborated in patients' liver samples. Jag1-dependent hepatic and immune defects thus interact to determine the fibrotic process in ALGS.
2024-08-27 | mRNA-specific readthrough of nonsense codons by antisense oligonucleotides (R-ASOs).
Nonsense mutations account for >10% of human genetic disorders, including cystic fibrosis, Alagille syndrome, and Duchenne muscular dystrophy. A nonsense mutation results in the expression of a truncated protein, and therapeutic strategies aim to restore full-length protein expression. Most strategies under development, including small-molecule aminoglycosides, suppressor tRNAs, or the targeted degradation of termination factors, lack mRNA target selectivity and may poorly differentiate between nonsense and normal stop codons, resulting in off-target translation errors. Here, we demonstrate that antisense oligonucleotides can stimulate readthrough of disease-causing nonsense codons, resulting in high yields of full-length protein in mammalian cellular lysate. Readthrough efficiency depends on the sequence context near the stop codon and on the precise targeting position of an oligonucleotide, whose interaction with mRNA inhibits peptide release to promote readthrough. Readthrough-inducing antisense oligonucleotides (R-ASOs) enhance the potency of non-specific readthrough agents, including aminoglycoside G418 and suppressor tRNA, enabling a path toward target-specific readthrough of nonsense mutations in CFTR, JAG1, DMD, BRCA1 and other mutant genes. Finally, through systematic chemical engineering, we identify heavily modified fully functional R-ASO variants, enabling future therapeutic development.
2024-07-08 | Management of Refractory Pruritus in Alagille Syndrome with Dupilumab Treatment: Case Report
Alagille syndrome (ALGS) is an autosomal dominant multisystem disorder with a reported incidence of 1:30,000 live births. ALGS-associated cholestasis presents in infancy and manifests with severe pruritus often leading to scratching, skin scarring, and resulting lichenoid processes. In fact, pruritus has been considered one of the most troublesome symptoms in this syndrome. Medical management for pruritus secondary to ALGS remains mostly targeted on supportive care with a variety of options including rifampin, ursodiol, and ileal bile acid transport inhibitors with promising results.
proteins
2026-02-01 | Immune-mediated platelet dysfunction with spontaneous formation of aggregates in pediatric end-stage liver disease: A case report
Introduction A 12-year-old girl with Alagille syndrome was admitted with progressive liver failure and subsequently listed for liver transplantation. Furthermore, the patient was born with tetralogy of Fallot, for which corrective surgery was performed. Eleven years after surgery, a stent was implanted in the pulmonary artery due to progressive pulmonary stenosis. As expected in advanced hepatic insufficiency, she developed thrombocytopenia (baseline 100-120 Tsd/µl) and reduced vitamin K-dependent clotting factors. In May, platelet counts suddenly became immeasurable due to pronounced spontaneous platelet aggregation, fluctuating over time. Pseudothrombocytopenia was excluded. Light transmission aggregometry revealed absent aggregation in response to arachidonic acid and ristocetin 1mg/ml, consistent with a Bernard–Soulier- and Aspirin-like phenotype. Since the glycoprotein profile was normal, it appeared to be an acquired disorder, even though there was no solid evidence of any specific antibodies. In order to demonstrate the presumed antibodies indirectly, mixing studies were performed. When donor platelets were combined with the patient’s plasma, aggregation responses to ristocetin 1M and arachidonic acid improved, followed by gradual desaggregation. However, donor plasma combined with the patient’s platelets did not improve aggregation, suggesting that antibodies were primarily platelet-bound. Peripheral blood smears showed fragmented erythrocytes and complement activity was elevated, indicating microangiopathy. During pre-transplant evaluation, acquired von Willebrand syndrome was also diagnosed, as expected following stent angioplasty. Method Light transmission aggregometry Glycoprotein-specific ELISA Results Subsequent to liver transplantation, the patient was treated with von-Willebrand-Factor-containing factor VIII concentrate and regular platelet transfusions regardless of the absolute count. Tranexamic acid was avoided because of possible microangiopathy. Standard anticoagulation with unfractionated heparin was administered perioperatively. The liver transplantation proceeded without bleeding or thrombotic complications. Within one week after the last platelet transfusion, platelet count had normalized completely, and light transmission aggregometry confirmed full recovery of platelet function. Conclusion This case illustrates the complex coagulation abnormalities observed in end-stage liver disease, where hemostatic impairment may extend beyond reduced clotting factors to include Bernard–Soulier-like phenotype, and microangiopathy. Despite severe preoperative coagulopathy, precise perioperative management with targeted replacement therapy and cautious avoidance of prothrombotic agents enabled successful transplantation without bleeding events. Liver transplantation not only resolved hepatic failure but also led to rapid normalization of platelet counts and function, highlighting the reversible nature of these coagulation disorders once hepatic function is restored. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany
2024-01-31 | Spatially segregated defects and IGF1-responsiveness of hilar and peripheral biliary organoids from a model of Alagille syndrome.
Alagille syndrome (ALGS) manifests with peripheral intrahepatic bile duct (IHBD) paucity, which can spontaneously resolve. In a model for ALGS, Jag1Ndr/Ndr mice, this occurs with distinct architectural mechanisms in hilar and peripheral IHBDs. Here, we investigated region-specific IHBD characteristics and addressed whether IGF1, a cholangiocyte mitogen that is downregulated in ALGS and in Jag1Ndr/Ndr mice, can improve biliary outcomes. Intrahepatic cholangiocyte organoids (ICOs) were derived from hilar and peripheral adult Jag1+/+ and Jag1Ndr/Ndr livers (hICOs and pICOs, respectively). ICOs were grown in Matrigel or microwell arrays, and characterized using bulk RNA sequencing, immunofluorescence, and high throughput analyses of nuclear sizes. ICOs were treated with IGF1, followed by analyses of growth, proliferation, and death. CellProfiler and Python scripts were custom written for image analyses. Key results were validated in vivo by immunostaining. Cell growth assays and transcriptomics demonstrated that Jag1Ndr/Ndr ICOs were less proliferative than Jag1+/+ ICOs. IGF1 specifically rescued survival and growth of Jag1Ndr/Ndr pICOs. Jag1Ndr/Ndr hICOs were the least proliferative, with lower Notch signalling and an enrichment of hepatocyte signatures and IGF uptake/transport pathways. In vitro (Jag1Ndr/Ndr hICOs) and in vivo (Jag1Ndr/Ndr hilar portal tracts) analyses revealed ectopic HNF4a+ hepatocytes. Hilar and peripheral Jag1Ndr/Ndr ICOs exhibit differences in Notch signalling status, proliferation, and cholangiocyte commitment which may result in cholangiocyte-to-hepatocyte transdifferentiation. While Jag1Ndr/Ndr pICOs can be rescued by IGF1, hICOs are unresponsive, perhaps due to their hepatocyte-like state and/or expression of IGF transport components. IGF1 represents a potential therapeutic for peripheral bile ducts.
2022-03-30 | Role of Immune Cells in Biliary Repair
The biliary system is comprised of cholangiocytes and plays an important role in maintaining liver function. Under normal conditions, cholangiocytes remain in the stationary phase and maintain a very low turnover rate. However, the robust biliary repair is initiated in disease conditions, and different repair mechanisms can be activated depending on the pathological changes. During biliary disease, immune cells including monocytes, lymphocytes, neutrophils, and mast cells are recruited to the liver. The cellular interactions between cholangiocytes and these recruited immune cells as well as hepatic resident immune cells, including Kupffer cells, determine disease outcomes. However, the role of immune cells in the initiation, regulation, and suspension of biliary repair remains elusive. The cellular processes of cholangiocyte proliferation, progenitor cell differentiation, and hepatocyte-cholangiocyte transdifferentiation during biliary diseases are reviewed to manifest the underlying mechanism of biliary repair. Furthermore, the potential role of immune cells in crucial biliary repair mechanisms is highlighted. The mechanisms of biliary repair in immune-mediated cholangiopathies, inherited cholangiopathies, obstructive cholangiopathies, and cholangiocarcinoma are also summarized. Additionally, novel techniques that could clarify the underlying mechanisms of biliary repair are displayed. Collectively, this review aims to deepen the understanding of the mechanisms of biliary repair and contributes potential novel therapeutic methods for treating biliary diseases.
2021-05-10 | Transcriptional profiling of pediatric cholestatic livers identifies three distinct macrophage populations.
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. 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. 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. 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.
2015-03-30 | CCN1 induces hepatic ductular reaction through integrin αvβ5–mediated activation of NF-κB
Liver cholestatic diseases, which stem from diverse etiologies, result in liver toxicity and fibrosis and may progress to cirrhosis and liver failure. We show that CCN1 (also known as CYR61), a matricellular protein that dampens and resolves liver fibrosis, also mediates cholangiocyte proliferation and ductular reaction, which are repair responses to cholestatic injury. In cholangiocytes, CCN1 activated NF-κB through integrin αvβ5/αvβ3, leading to Jag1 expression, JAG1/NOTCH signaling, and cholangiocyte proliferation. CCN1 also induced Jag1 expression in hepatic stellate cells, whereupon they interacted with hepatic progenitor cells to promote their differentiation into cholangiocytes. Administration of CCN1 protein or soluble JAG1 induced cholangiocyte proliferation in mice, which was blocked by inhibitors of NF-κB or NOTCH signaling. Knock-in mice expressing a CCN1 mutant that is unable to bind αvβ5/αvβ3 were impaired in ductular reaction, leading to massive hepatic necrosis and mortality after bile duct ligation (BDL), whereas treatment of these mice with soluble JAG1 rescued ductular reaction and reduced hepatic necrosis and mortality. Blockade of integrin αvβ5/αvβ3, NF-κB, or NOTCH signaling in WT mice also resulted in defective ductular reaction after BDL. These findings demonstrate that CCN1 induces cholangiocyte proliferation and ductular reaction and identify CCN1/αvβ5/NF-κB/JAG1 as a critical axis for biliary injury repair.
cell therapies
2026-08-12 | Long-Term Outcomes of Living Donor Liver Transplantation in Children With Alagille Syndrome: Results From Vanguard Multicenter Study of International Living Donor Liver Transplantation Group.
The morbidity and mortality after living donor liver transplantation (LDLT) in children with Alagille syndrome (AGS) are complex because of the multisystem involvement of the disease. Evidence on long-term outcomes and donor selection remains limited. This multicenter retrospective study included 49 pediatric patients with AGS who underwent LDLT between 2001 and 2020 at eight institutions in Japan, Korea, and Turkey. Clinical characteristics, transplant indications, donor selection, posttransplant growth, renal function, and complications were analyzed. The median age at LDLT was 1.1 years. Major indications for transplantation were severe growth failure (91.8%) and advanced liver disease with hepatic dysfunction. Based on donor evaluations, 11% of candidates were excluded due to genetic or anatomical concerns. The 5-year patient and graft survival rates were 93.7% and 91.5%, respectively. LDLT before 2 years of age was associated with significantly greater catch-up in height and weight. Long-term renal deterioration was observed, particularly beyond 15 years after transplantation, and older age at LDLT was an independent predictor of lower long-term estimated glomerular filtration rate. Cardiac anomalies were manageable with appropriate preoperative evaluation, whereas vasculopathies were observed after adolescence. A history of Kasai portoenterostomy did not significantly affect posttransplant outcomes. LDLT provides excellent short- and long-term outcomes in pediatric AGS. Timely LT may improve growth and preserve renal function before progressive multisystem complications become established. Long-term surveillance and comprehensive donor evaluation remain essential.
2025-03-28 | Liver transplantation in children: pre-transplantation preparation tactics
Liver transplantation (LT) from a living related donor is the only life-saving option for children with congenital liver diseases such as biliary atresia, Alagille syndrome, progressive familial intrahepatic cholestasis, and Byler disease, as well as metabolic disorders and acute or chronic liver failure. The development of LT from living related donors significantly reduces the waiting time for a donor organ. The success of the procedure largely depends on the quality of pre-transplantation preparation (PTP) of both donor and recipient. Aim - to study the features of PTP in children with cholestatic liver diseases for successful LT. Materials and methods. 37 children with biliary atresia underwent PTP between 2005 and 2023. In 36 cases, LT was performed using a living related donor; in one case, split-liver transplantation (SPLIT-LT) was used. PTP lasted 3–6 months and included infection focus sanitation, correction of congenital anomalies, emergency status assessment, and evaluation of physical and psycho-emotional development. All examinations followed current international standards. Results. All transplantations were successful. After PTP, improvements were observed in hematological parameters, functional and neuropsychological development, and reduced anxiety levels. All transplant centers acknowledged the high quality of PTP; no child was refused transplantation due to inadequate preparation. The key readiness criteria were a compensated clinical state and a safe bacterial environment. Conclusions. Compliance with regulatory standards and protocols for PTP ensures successful pediatric LT and protects donor health. PTP improves hematological, somatic, and psycho-emotional indicators, reduces risks, and increases the effectiveness of transplantation. Our experience with PTP aligns with international standards. The research was carried out in accordance with the principles of the Declaration of Helsinki. Informed consent of the child and child's parents was obtained for the research. No conflict of interest was declared by the author.
2024-08-28 | Generation of human iPSC-derived 3D bile duct within liver organoid by incorporating human iPSC-derived blood vessel.
In fetal development, tissue interaction such as the interplay between blood vessel (BV) and epithelial tissue is crucial for organogenesis. Here we recapitulate the spatial arrangement between liver epithelial tissue and the portal vein to observe the formation of intrahepatic bile ducts (BDs) from human induced pluripotent stem cells (hiPSC). We co-culture hiPSC-liver progenitors on the artificial BV consisting of immature smooth muscle cells and endothelial cells, both derived from hiPSCs. After 3 weeks, liver progenitors within hiPSC-BV-incorporated liver organoids (BVLO) differentiate to cholangiocytes and acquire epithelial characteristics, including intercellular junctions, microvilli on the apical membrane, and secretory functions. Furthermore, liver surface transplanted-BVLO temporarily attenuates cholestatic injury symptoms. Single cell RNA sequence analysis suggests that BD interact with the BV in BVLO through TGFβ and Notch pathways. Knocking out JAG1 in hiPSC-BV significantly attenuates bile duct formation, highlighting BVLO potential as a model for Alagille syndrome, a congenital biliary disease. Overall, we develop a novel 3D co-culture method that successfully establishes functional human BDs by emulating liver epithelial-BV interaction.
2024-08-21 | Durability of Aortic Homografts in Pulmonary Atresia and Major Aortopulmonary Collateral Arteries.
Objectives: It is well-known that right ventricle-to-pulmonary artery homograft conduit durability is worse for smaller conduits and smaller/younger patients. However, there is limited literature on age and conduit-size specific outcomes, or on the role of conduit oversizing. Methods: Patients diagnosed with tetralogy of Fallot and major aortopulmonary collateral arteries undergoing right ventricular outflow tract (RVOT) reconstruction with a valved aortic homograft conduit from November 2001 through March 2023, at our institution were included. Conduits were grouped and evaluated by diameter, diameter Z-score, and patient age at implant. The primary time-related outcome was freedom from RVOT reintervention. Factors associated with freedom from time-related outcomes were assessed with univariable Cox regression analysis. Results: A total of 863 RVOT conduits were implanted in 722 patients. On multivariable analysis, younger age, male sex, Alagille syndrome, smaller diameter of the conduit, and smaller Z-score were associated with shorter freedom from reintervention. Among patients with smaller diameter conduits, larger Z-scores were associated with longer freedom from conduit reintervention (P < .001). Transcatheter interventions were commonly used to extend conduit lifespan across ages and conduit sizes. Conclusions: Larger conduit diameter, older age, and higher conduit Z-score were associated with longer freedom from reintervention in patients undergoing RVOT reconstruction in this cohort. Oversizing of conduits, even beyond a Z-score of 4, is generally appropriate.
2024-06-28 | Alagille syndrome in the clinical practice of a paediatric surgeon
Alagille syndrome (AGS) is one of the most problematic for the diagnosis of hereditary, multisystem, cholestatic liver diseases in combination with other congenital defects. Timely diagnosis and treatment (including liver transplantation - LT) improves the quality of life (QoL), prevents irreversible liver changes, multiple organ failure and mortality. Aim – to study the possibilities and features of the differential diagnosis of AGS, the impact of complex treatment, surgical correction (including LT) on the course of the disease, the dynamics of clinical and laboratory indicators, physical development (FD) and neuropsychological development (NPD), QoL. Materials and methods. Verification of the diagnosis of AGS included clinical, biochemical, instrumental examinations, genetic markers of AGS. Quality of life was evaluated: assessment of skin itching (on a categorical scale, according to the visual analogue scale of pruritus; the level of anxiety was determined according to the Hamilton scale (modified). FD and NPD were evaluated by pediatricians and pediatric neurologists before and after treatment. The assessment of FD according to centile tables was carried out in accordance with WHO standards. The assessment of NPD was carried out: development delay for one, two, three epicrisis terms; degree of NPD delay. Results. Against the background of treatment, biochemical and clinical indicators improved. Itching of the skin (according to the categorical scale of itching, visual analogue scale of pruritus), decreased the anxiety index. The dynamics of the FD and NPD were positive. Conclusions. Modern possibilities of diagnosis of AGS include genetic and histological methods, which makes it possible to start pathogenetic therapy early, to decide the time and ways of surgical intervention (including LT). The presence of concomitant congenital defects of other organs and systems, the characteristic appearance of children with AGS require a multidisciplinary examination with the involvement of multidisciplinary specialists. Complex and timely treatment of AGS contributes to the normalization of clinical and biochemical indicators, FD, NPD, quality of life. Radical treatment of AGS by means of LT should be considered before the period of irreversible multiorgan changes, taking into account the preservation of FD and NPD. The research was carried out in accordance with the principles of the Declaration of Helsinki. Informed consent of the child and child's parents was obtained for the research. The author declares no conflict of interest.
small molecules
2026-07-25 | Three high throughput compatible cell-based assays for identifying small molecule JAG1 upregulators for Alagille syndrome.
Haploinsufficiency disorders arise when loss of function mutations in one allele of a gene reduce gene dosage below the level required for normal physiology. Pharmacologic upregulation of the remaining functional allele represents a promising therapeutic strategy but requires screening assays capable of detecting modest changes in endogenous gene expression. Here we developed and compared three high throughput cell-based assays for identifying small molecule upregulators of JAG1, the gene most frequently mutated in Alagille syndrome (ALGS). The assays measure JAG1 expression at different molecular levels: RNA fluorescence in situ hybridization (RNA FISH) for JAG1 mRNA, immunofluorescence (IF) for endogenous JAG1 protein, and a HiBiT luminescence assay using CRISPR engineered LX-2 hepatic stellate cells expressing HiBiT tagged JAG1. Each assay was optimized in 384-well format and benchmarked using a panel of 32 histone deacetylase inhibitors (HDACi), compounds known to broadly increase gene expression. All three assays detected JAG1 upregulation and identified overlapping sets of active compounds. The homogeneous HiBiT assay showed the most favorable high throughput screening statistics (S/B = 2.7 and Z' > 0.5) and the lowest well to well variability, whereas the RNA FISH and IF assays provided higher signal to basal ratios and single cell resolution. Entinostat, Mocetinostat, and Chidamide were consistently identified as the most potent JAG1 upregulators across all assays. These complementary assays provide a flexible platform for identifying small molecule modulators of gene dosage and may be broadly applicable to drug discovery efforts targeting haploinsufficiency diseases.
2026-06-18 | Heterozygous variants in NOTCH2 in a cohort of juvenile and adult patients with cholestatic liver disease: Disease modifiers or innocent bystanders?
Background and objective: Genetic cholestatic liver diseases are increasingly stratified using NGS. The resulting information can guide treatment with novel drugs such as IBAT inhibitors, which have demonstrated efficacy in congenital liver disorders including Alagille syndrome and PFIC. We hypothesised [for full text, please go to the a.m. URL]
2026-06-18 | Use of genetic analysis in adult cholestatic liver disease: lessons from progressive paediatric syndromes and cohort studies.
The increasing availability and decreasing costs of DNA sequencing have resulted in the re-grouping of rare, severe paediatric cases of progressive familial intrahepatic cholestasis (PFIC) with more frequent, later-onset cases of cholestasis (eg, intrahepatic cholestasis of pregnancy, benign recurrent intrahepatic cholestasis, low phospholipid-associated cholelithiasis) under the umbrella of genetic cholestasis. The common denominator is the presence of functional variants in the PFIC-associated genes, predominantly in ABCB4, ABCB11 and ATP8B1, which cause PFIC types 1-3. Several other congenital diseases such as Alagille syndrome and alpha1-antitrypsin deficiency comprise cholestatic pruritus as frequent symptoms.With the availability of intestinal bile acid transporter inhibitors (IBATi) as new and efficacious therapeutics for pruritus, the most debilitating symptom of PFIC, it is essential to envision their usefulness for patients with later-onset cholestatic liver disease suffering from pruritus.In this review, we summarise published studies on the genetic makeup of patients with paediatric, juvenile and adult-onset cholestasis, and discuss their findings with respect to genotype-specific treatment with IBATi, ursodeoxycholic acid, or alternative drugs. The aim is to provide an overview of the genetic variants likely to be encountered in future sequencing investigations of patients with cholestatic liver diseases, and how to translate this genetic information into personalised treatment recommendations.
2026-04-28 | JAG1-independent Notch activation via Silymarin-mediated DLL4 upregulation
Silymarin from Silybum marianum enhances DLL4 (Delta-like ligand 4) expression in hepatocytes through NRF2-mediated transcriptional activation, providing alternative Notch signaling pathway activation to compensate for deficient JAG1-mediated signaling in Alagille syndrome
2026-03-25 | Notch signaling in liver diseases: mechanistic insights and therapeutic implications.
The Notch signaling pathway represents an evolutionarily conserved mechanism of intercellular communication that plays critical roles in organ development and tissue homeostasis. However, its functions in liver physiology and pathology demonstrate remarkable context-dependent characteristics, with dysregulated signaling contributing to various liver disorders. This review systematically summarizes the complex roles of Notch signaling in liver health and disease. It comprehensively examines the pathway's essential functions in biliary development, hepatic regeneration, and metabolic homeostasis, while providing a detailed analysis of its pathogenic mechanisms in conditions including Alagille syndrome, drug-induced liver injury, non-alcoholic fatty liver disease, liver fibrosis, hepatocellular carcinoma, and intrahepatic cholangiocarcinoma. Our review particularly emphasizes the dual function of Notch signaling in hepatobiliary malignancies, where it can exert either oncogenic or tumor-suppressive effects depending on specific cellular contexts, molecular interactions, and microenvironmental cues. Furthermore, we highlight the evolution of therapeutic strategies from broad-spectrum γ-secretase inhibitors to more precise approaches involving ligand-specific antibodies, transcriptional complex blockers, and pathway agonists, while addressing persistent challenges in clinical translation including on-target toxicities, compensatory resistance mechanisms, and context-dependent responses. Looking forward, this review outlines promising research directions featuring biomarker-guided patient stratification, rational combination therapies with immune checkpoint inhibitors, and spatiotemporally precise regulatory strategies. By integrating foundational knowledge with recent advances, this work provides valuable insights for understanding Notch signaling's complex roles in liver pathophysiology and for developing novel therapeutic interventions.
gene therapies
2026-05-04 | From supportive to targeted treatment strategies: the changing landscape of therapeutics in Alagille syndrome
1. Alagille syndrome (ALGS) is an autosomal dominant developmental disorder characterized by highly variable, multisystem involvement and caused by pathogenic variants in the genes Jagged1 (JAG1) a...
2025-10-19 | Pediatric Liver Diseases: Next-Generation Therapies.
With recent advances in molecular medicine, there has been a transformation of the landscape of pediatric liver disease therapeutics. The advent of gene editing technologies, RNA therapeutics, and molecular chaperone therapies has led to precise targeting of liver pathology. This review aims to shed light on recent breakthroughs in liver-directed nucleic acid therapies such as small interfering RNA, mRNA editing, and CRISPR-based approaches, with a special focus on their application in alpha-1 antitrypsin deficiency, hepatitis B, cystic fibrosis-related liver disease, metabolic dysfunction-associated steatotic liver disease, Alagille syndrome, progressive familial intrahepatic cholestasis, and acute hepatic porphyria.
2025-05-31 | Adeno-associated Virus-mediated Silencing of Sox4 Leads to Long-Term Amelioration of Liver Phenotypes in Mouse Models of Alagille Syndrome.
In patients with Alagille syndrome (ALGS), bile duct paucity often leads to severe cholestatic phenotypes for which liver transplantation remains the only definitive treatment. No Food and Drug Administration-approved mechanism-based strategies exist to enhance biliary development in ALGS or other diseases with bile duct paucity. We aimed to identify a therapeutic target to address this unmet need. Preclinical ALGS mouse models lacking 1 copy of Jag1 with or without conditional deletion of 1 or both copies of Sox9 were used. Sox4 levels were reduced genetically or with adeno-associated virus 8 (AAV8) vectors driving a Sox4-silencing sequence. Liver histology, biliary tree ink injection, serum chemistry, RNAscope (on mouse and human livers), mouse liver single-cell RNA-sequencing, and reanalysis of published human liver bulk RNA-sequencing were performed. Conditional removal of 1 copy of Sox4 in mouse liver significantly improved the ALGS liver phenotypes in a Sox9-dependent manner. An increase in Sox4/SOX4 expression in early postnatal Jag1-heterozygous mouse livers and ALGS patient livers was observed. single-cell RNA-sequencing revealed the appearance of an intermediate hepatobiliary cluster co-expressing Sox4 and Sox9 in Jag1-heterozygous livers. AAV8-mediated Sox4 knockdown, ubiquitously or driven by the hepatocyte-specific thyroxine-binding globulin promoter, led to long-term improvement of ALGS liver phenotypes upon injection at postnatal day 1. AAV8 injection at postnatal day 15-after the appearance of liver necrosis-led to the incorporation of some transduced cells into bile ducts and phenotypic improvement. Preclinical studies provide proof of principle for postnatal AAV-mediated Sox4 knockdown in thyroxine-binding globulin+ cells as a therapeutic approach for ALGS liver disease.
2021-04-14 | Sox9 Is a Modifier of the Liver Disease Severity in a Mouse Model of Alagille Syndrome.
Alagille syndrome (ALGS) is a multisystem developmental disorder characterized by bile duct (BD) paucity, caused primarily by haploinsufficiency of the Notch ligand jagged1. The course of the liver disease is highly variable in ALGS. However, the genetic basis for ALGS phenotypic variability is unknown. Previous studies have reported decreased expression of the transcription factor SOX9 (sex determining region Y-box 9) in late embryonic and neonatal livers of Jag1-deficient mice. Here, we investigated the effects of altering the Sox9 gene dosage on the severity of liver disease in an ALGS mouse model. Conditional removal of one copy of Sox9 in Jag1+/- livers impairs the biliary commitment of cholangiocytes and enhances the inflammatory reaction and liver fibrosis. Loss of both copies of Sox9 in Jag1+/- livers further worsens the phenotypes and results in partial lethality. Ink injection experiments reveal impaired biliary tree formation in the periphery of P30 Jag1+/- livers, which is improved by 5 months of age. Sox9 heterozygosity worsens the P30 biliary tree phenotype and impairs the partial recovery in 5-month-old animals. Notably, Sox9 overexpression improves BD paucity and liver phenotypes in Jag1+/- mice without ectopic hepatocyte-to-cholangiocyte transdifferentiation or long-term liver abnormalities. Notch2 expression in the liver is increased following Sox9 overexpression, and SOX9 binds the Notch2 regulatory region in the liver. Histological analysis shows a correlation between the level and pattern of SOX9 expression in the liver and outcome of the liver disease in patients with ALGS. Our results establish Sox9 as a dosage-sensitive modifier of Jag1+/- liver phenotypes with a permissive role in biliary development. Our data further suggest that liver-specific increase in SOX9 levels is a potential therapeutic approach for BD paucity in ALGS.
2015-11-30 | Alagille Syndrome Mimicking Biliary Atresia in Early Infancy
Alagille syndrome may mimic biliary atresia in early infancy. Since mutations in JAG1 typical for Alagille syndrome type 1 have also been found in biliary atresia, we aimed to identify JAG1 mutations in newborns with proven biliary atresia (n = 72). Five biliary atresia patients with cholestasis, one additional characteristic feature of Alagille syndrome and ambiguous liver histology were single heterozygotes for nonsense or frameshift mutations in JAG1. No mutations were found in the remaining 67 patients. All "biliary atresia" carriers of JAG1 null mutations developed typical Alagille syndrome at the age of three years. Our data do not support association of biliary atresia with JAG1 mutations, at least in Czech patients. Rapid testing for JAG1 mutations could prevent misdiagnosis of Alagille syndrome in early infancy and improve their outcome.
other
2025-09-22 | Antisense oligonucleotide-mediated upregulation of Jag1 ameliorates liver disease phenotypes in a mouse model of Alagille syndrome.
Alagille syndrome (ALGS) is a rare genetic disorder that affects multiple organ systems, especially the liver, leading to life-threatening complications. In most cases, ALGS is caused by haploinsufficient mutations in the JAG1 gene, resulting in impaired liver bile duct development during early childhood. Therefore, increasing JAG1 protein levels in ALGS patients offers a potential therapeutic approach. In this study, we designed antisense oligonucleotides (ASOs) targeting the JAG1 mRNA to enhance translation through different mechanisms. We found that certain ASOs targeting the upstream open reading frame (uORF) increased JAG1 protein levels in various cell lines and ALGS patient-derived cells. Optimized ASOs also increased Jag1 protein levels in normal mouse liver for up to 2-fold, accompanied by elevated levels of cleaved Notch1 protein, suggesting that the increased Jag1 protein was functionally active. Importantly, ASO treatment increased Jag1 protein in Jag1 +/- mouse model. When newborn Jag1 +/- mice were treated with ASO, improved bile duct development was observed, along with trends of reduced plasma bile acids, bilirubin, and triglyceride levels, implying improved liver function. Together, these results suggest that ASO-induced JAG1 upregulation may provide a promising therapeutic opportunity for ALGS patients, especially when treated at an early age.
2025-03-05 | Alagille Syndrome: Unraveling the Complexities of Genotype-Phenotype Relationships and Exploring Avenues for Improved Diagnosis and Treatment.
Alagille syndrome (ALGS) is a rare genetic disorder caused by mutations in the JAG1 and NOTCH2 genes, leading to a wide range of clinical manifestations. This review explores the complex genetic and clinical landscape of ALGS, emphasizing the challenges in understanding genotype-phenotype relationships due to its rarity and the lack of suitable research models. The review projects a clinical overview of the disease, emphasizing the influence of potential gene modifiers on its clinical presentation and the lack of mechanistic studies for over 100 mutations identified in the last 24 years from various populations, representing a significant gap in our current knowledge and advocating for further exploration. The review addresses the diagnostic challenges posed by the variable expressivity and overlapping symptoms of ALGS. It summarizes current treatment options and discusses emerging approaches such as antisense oligonucleotides (ASOs) and gene therapies. Further, the need for improved diagnostic tools, a deeper understanding of the underlying mechanisms, and the development of targeted therapies are emphasized using zebrafish and mice models, as well as genome editing for variant analysis and stem cell organoid models for disease modeling and drug discovery. The importance of cohort-based studies in understanding the natural history and outcomes of ALGS in diverse populations is highlighted. The review concludes by emphasizing the need for multi-disciplinary collaborative research to address the challenges in ALGS diagnosis, prognosis, and treatment, particularly for underrepresented populations.
2024-10-03 | Jag1 insufficiency alters liver fibrosis via T cell and hepatocyte differentiation defects.
Fibrosis contributes to tissue repair, but excessive fibrosis disrupts organ function. Alagille syndrome (ALGS, caused by mutations in JAGGED1) results in liver disease and characteristic fibrosis. Here, we show that Jag1Ndr/Ndr mice, a model for ALGS, recapitulate ALGS-like fibrosis. Single-cell RNA-seq and multi-color flow cytometry of the liver revealed immature hepatocytes and paradoxically low intrahepatic T cell infiltration despite cholestasis in Jag1Ndr/Ndr mice. Thymic and splenic regulatory T cells (Tregs) were enriched and Jag1Ndr/Ndr lymphocyte immune and fibrotic capacity was tested with adoptive transfer into Rag1-/- mice, challenged with dextran sulfate sodium (DSS) or bile duct ligation (BDL). Transplanted Jag1Ndr/Ndr lymphocytes were less inflammatory with fewer activated T cells than Jag1+/+ lymphocytes in response to DSS. Cholestasis induced by BDL in Rag1-/- mice with Jag1Ndr/Ndr lymphocytes resulted in periportal Treg accumulation and three-fold less periportal fibrosis than in Rag1-/- mice with Jag1+/+ lymphocytes. Finally, the Jag1Ndr/Ndr hepatocyte expression profile and Treg overrepresentation were corroborated in patients' liver samples. Jag1-dependent hepatic and immune defects thus interact to determine the fibrotic process in ALGS.
2024-08-27 | mRNA-specific readthrough of nonsense codons by antisense oligonucleotides (R-ASOs).
Nonsense mutations account for >10% of human genetic disorders, including cystic fibrosis, Alagille syndrome, and Duchenne muscular dystrophy. A nonsense mutation results in the expression of a truncated protein, and therapeutic strategies aim to restore full-length protein expression. Most strategies under development, including small-molecule aminoglycosides, suppressor tRNAs, or the targeted degradation of termination factors, lack mRNA target selectivity and may poorly differentiate between nonsense and normal stop codons, resulting in off-target translation errors. Here, we demonstrate that antisense oligonucleotides can stimulate readthrough of disease-causing nonsense codons, resulting in high yields of full-length protein in mammalian cellular lysate. Readthrough efficiency depends on the sequence context near the stop codon and on the precise targeting position of an oligonucleotide, whose interaction with mRNA inhibits peptide release to promote readthrough. Readthrough-inducing antisense oligonucleotides (R-ASOs) enhance the potency of non-specific readthrough agents, including aminoglycoside G418 and suppressor tRNA, enabling a path toward target-specific readthrough of nonsense mutations in CFTR, JAG1, DMD, BRCA1 and other mutant genes. Finally, through systematic chemical engineering, we identify heavily modified fully functional R-ASO variants, enabling future therapeutic development.
2024-07-08 | Management of Refractory Pruritus in Alagille Syndrome with Dupilumab Treatment: Case Report
Alagille syndrome (ALGS) is an autosomal dominant multisystem disorder with a reported incidence of 1:30,000 live births. ALGS-associated cholestasis presents in infancy and manifests with severe pruritus often leading to scratching, skin scarring, and resulting lichenoid processes. In fact, pruritus has been considered one of the most troublesome symptoms in this syndrome. Medical management for pruritus secondary to ALGS remains mostly targeted on supportive care with a variety of options including rifampin, ursodiol, and ileal bile acid transport inhibitors with promising results.
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Drug Discovery Landscape
6 orphan drug designations for Alagille syndrome, including 3 approved therapies.
6 orphan drug designations for Alagille syndrome, including 3 approved therapies.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
27mer antisense oligonucleotide with methoxyethyl, 2'-O-methyl, and phosphorothioate modifications | oligonucleotides | FDA | 2024-10-24 | — | Arnatar Therapeutics, Inc. |
odevixibat [Bylvay] | small molecules | FDA | 2018-10-15 | 2023-06-13 | Ipsen Biopharmaceuticals, Inc. |
(4R,5R)-1-[[4-[[4-[3,3-dibutyl-7-(dimethylamino)-2,3,4,5-tetrahydro-4-hydroxy-1,1-dioxido-1-benzothiepin-5-yl]phenoxy]methyl]phenyl]methyl]-4-aza-1-azoniabicyclo[2.2.2]octane chloride [Livmarli] | small molecules | EMA | 2013-12-18 | 2022-12-12 | Mirum Pharmaceuticals International B.V. |
maralixibat [Livmarli] | small molecules | FDA | 2013-09-04 | 2021-09-29 | Mirum Pharmaceuticals, Inc. |
Odevixibat sesquihydrate [Bylvay] | small molecules | EMA | 2012-08-09 | — | Albireo AB |
Buffered Ursodeoxycholic Acid | small molecules | FDA | 2004-09-03 | — | Digestive Care, Inc. |
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