Laminin 511-E8, an autoantigen in IgG4-related cholangitis, contributes to cholangiocyte protection

Background & Aims

IgG4-related cholangitis (IRC) is the hepatobiliary manifestation of IgG4-related disease. Anti-laminin 511-E8 autoantibodies have been identified in its pancreatic manifestation. Laminin 511-E8 promotes endothelial barrier function, lymphocyte recruitment, and cholangiocyte differentiation. Here, we investigate anti-laminin 511-E8 autoantibody presence in IRC, and mechanisms via which laminin 511 may contribute to cholangiocyte protection.

Methods

Anti-laminin 511-E8 serum autoantibody positivity was assessed by ELISA. RNA sequencing and RT-qPCR were performed on human H69 cholangiocytes treated with recombinant laminin 511-E8. H69 cholangiocytes were subjected to shRNA knockdown targeting genes encoding laminin 511 (LAMA5, LAMB1, LAMC1) or treated with recombinant laminin 511-E8. Cholangiocellular bile acid influx was quantified radiochemically using 22,23-3H-glycochenodeoxycholic acid (GCDC). GCDC-induced apoptosis was determined by Caspase-3/7 assays. Cholangiocellular barrier function was assessed by FITC-Dextran permeability assays. Immunofluorescent staining of laminin 511 and claudin 1 was performed on extrahepatic bile duct tissue of control and anti-laminin 511-E8 positive individuals with IRC.

Results

Seven out of 52 individuals with IRC had autoantibodies against laminin 511-E8. Recombinant laminin 511-E8 led to differential expression of genes involved in secretion, barrier function, and inflammation. Knockdown of laminin 511 constituents increased toxic bile acid permeation and GCDC-induced apoptosis. Laminin 511-E8 treatment decreased toxic bile acid permeation and dose-dependently alleviated GCDC-induced apoptosis. LAMA5 and LAMC1 knockdown increased transepithelial permeability. Laminin 511-E8 treatment reduced transepithelial permeability and prevented T lymphocyte-induced barrier dysfunction. Laminin 511 and claudin 1 staining patterns appeared altered in anti-laminin 511-E8 positive individuals with IRC.

Conclusions

Laminin 511-E8 is an autoantigen in subsets of individuals with IRC. Laminin 511 enhances cholangiocellular barrier function and protects cholangiocytes against T lymphocyte-induced barrier dysfunction, toxic bile acid permeation and bile acid-induced apoptosis.

Impact and implications

A subset of patients with IgG4-related cholangitis (IRC) has autoantibodies against laminin 511-E8. In human cholangiocytes, laminin 511 protects against (T lymphocyte-induced) epithelial barrier dysfunction and hydrophobic bile acids. Laminin 511 and claudin 1 staining may be altered in extrahepatic bile ducts of patients with IRC who are anti-laminin 511-E8 positive. This makes it tempting to speculate that a decreased epithelial barrier function with attraction of immune cells and impaired bicarbonate secretion as a result of dysfunction of laminin 511 by autoantibody binding could potentially be a common systemic pathogenic mechanism in a subset of patients with IgG4-RD.

Prominent role of gut dysbiosis in the pathogenesis of cystic fibrosis-related liver disease in mice

BACKGROUND & AIMS

Cystic fibrosis-related liver disease (CFLD) is a chronic cholangiopathy that increases morbidity and mortality in patients with CF. Current treatments are unsatisfactory, and incomplete understanding of CFLD pathogenesis hampers therapeutic development. We have previously shown that mouse CF cholangiocytes respond with excessive inflammation to LPS. Thus, we investigated the role of the gut-liver axis in the pathogenesis of CFLD.

METHODS

Wild-type (WT), whole-body CFTR knockout (CFTR-KO) and gut-corrected (CFTR-KO-GC) mice were studied. Liver changes were assessed by immunohistochemistry and single-cell transcriptomics (scRNAseq), inflammatory mediators were analyzed by proteome array, faecal microbiota by 16S rRNAseq and gut permeability by FITC-dextran assay.

RESULTS

The livers of CFTR-KO mice showed ductular proliferation and periportal inflammation, whereas livers of CFTR-KO-GC mice had no evident pathology. scRNAseq analysis of periportal cells showed increased presence of neutrophils, macrophages and T-cells and activation of pro-inflammatory and pathogen-mediated immune pathways in CFTR-KO livers, consistent with a response to gut-derived stimuli. CFTR-KO mice exhibited gut dysbiosis with enrichment of Enterobacteriaceae and Enterococcus spp., which was associated with increased intestinal permeability and mucosal inflammation, whereas gut dysbiosis and inflammation were absent in CFTR-KO-GC mice. Treatment with nonabsorbable antibiotics ameliorated intestinal permeability and liver inflammation in CFTR-KO mice. Faecal microbiota transfer from CFTR-KO to germ-free WT mice did not result in dysbiosis nor liver pathology, indicating that defective intestinal CFTR is required to maintain dysbiosis.

CONCLUSION

Defective CFTR in the gut sustains a pathogenic microbiota, creates an inflammatory milieu, and alters intestinal permeability. These changes are necessary for the development of cholangiopathy. Restoring CFTR in the intestine or modulating the microbiota could be a promising strategy to prevent or attenuate liver disease.

IMPACT AND IMPLICATIONS

Severe cystic fibrosis-related liver disease (CFLD) affects 10% of the patients and contributes to increased morbidity and mortality of CF patients. Treatment options remain limited due to a lack of understanding of the disease pathophysiology. The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mediates Cl- and HCO3- secretion in the biliary epithelium and its defective function is thought to cause cholestasis and excessive inflammatory responses in CF. However, our study in CFTR-knockout mice demonstrates that microbial dysbiosis, combined with increased intestinal permeability caused by defective CFTR in the intestinal mucosa, acts as a necessary co-factor for the development of CFLD-like liver pathology in mice. These findings uncover a major role for the gut microbiota in CFLD pathogenesis and call for further investigation and clinical validation to develop targeted therapeutic strategies acting on the gut-liver axis in CF.

Features of biliary tract diseases in ketamine abusers: a systematic review of case reports

BACKGROUND AND AIMS

Anesthesiologists prefer ketamine for certain surgeries due to its effectiveness as a non-competitive inhibitor of the N-methyl-D-aspartate receptor in the brain. Recently, this agent has also shown promise as an antidepressant. However, ketamine can cause hallucinogenic effects and is sometimes abused as an illicit drug. Ketamine abuse has been associated with liver and bile duct complications. This systematic study aims to better understand cholangiopathy in ketamine abusers by reviewing case reports.

METHODS AND MATERIAL

In this systematic review, a comprehensive literature search was conducted with the terms "biliary tract diseases" and "ketamine". Case reports and case series of adult patients with documented ketamine abuse and reported cholangiopathy or biliary tract disease were included. We extracted the data of relevant information and the results were reported through narrative synthesis and descriptive statistics.

RESULTS

A total of 48 studies were initially identified, and 11 studies were finally included in the review. The mean age of the patients was 25.88 years. Of the 17 patients, 64.7% were men. Symptoms often included abdominal pain, nausea, and vomiting. Most patients were discharged with improved symptoms and liver function. Common bile duct dilation and other findings were observed in imaging results and other diagnostic studies.

CONCLUSION

This review highlights the diverse presentations and diagnostic modalities used in ketamine-induced cholangiography. These patients tend to be young men with deranged liver function tests and abdominal pain, which should be taken into consideration. These patients often require a multidisciplinary approach in their management.

Diagnostic Tests in Primary Sclerosing Cholangitis: Serology, Elastography, Imaging, and Histology

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by progressive inflammation and fibrosis of the biliary tree leading to biliary strictures, cholangitis, and cirrhosis. Early in presentation, patients may have normal liver tests, though over time develop a cholestatic pattern of liver injury. Diagnosis is made radiographically with magnetic resonance or endoscopic cholangiography. While several autoantibodies are associated with PSC, none have proven to have adequate diagnostic utility. Liver biopsy is rarely recommended unless to evaluate for small-duct PSC or overlap syndrome. Elastography, in various forms, is an effective, non-invasive modality to evaluate liver fibrosis in PSC.

The liver in sickle cell disease

Liver involvement in SCD patients is frequent but often misdiagnosed or underestimated, except in case of advanced liver diseases. Because of so far poorly recognized forms of chronic SCD-related vascular injury that can silently evolved towards end stages or facilitate ACLF, any persisting liver function tests abnormalities should be carefully investigated, following the above proposed algorithm. Work up and management must be considered multidisciplinary in relationship with a Hepatologist. Early SCD hepatopathy should prompt revision of SCD management to prevent further liver injury and decompensation, discussing transfusion exchanges and hydro urea when not yet initiated, and control for any cofactor of liver injury. The role of HSCT in early SCD hepatopathies also deserves evaluation. In advanced SCD hepatopathies, liver transplantation, which has been rarely performed so far, is the only therapeutic option associated with improved survival. It should definitely be discussed- either electively in case of decompensation in SCD cirrhosis or jaundice/recurrent cholangitis in cholestatic diseases, with excellent outcome, - or emergently in case of ALF or ACLF with more mitigate results. To improve knowledge and management of SCD liver diseases, creation of national and international registries, as well as longitudinal observational cohorts are encouraged.

Post-COVID-19 cholangiopathy: Systematic review

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has had a profound impact on global health, primarily characterized by severe respiratory illness. However, emerging evidence suggests that COVID-19 can also lead to secondary sclerosing cholangitis (SC), referred to as post-COVID-19 cholangiopathy.

AIM

To synthesize currently reported cases to assess the current state of knowledge on post-COVID-19 cholangiopathy.

METHODS

Medical Subject Headings and Health Sciences Descriptors were used to retrieve relevant studies, which were combined using Boolean operators. Searches were conducted on electronic databases including Scopus, Web of Science, and MEDLINE (PubMed). Studies published in English, Spanish, or Portuguese were included, with no restrictions on the publication date. Additionally, the reference lists of retrieved studies were manually searched. Simple descriptive analyses were used to summarize the results. Then the data were extracted and assessed based on Reference Citation Analysis (https://www.referencecitationanalysis.com/).

RESULTS

The initial search yielded a total of 192 articles. After screening, 85 articles were excluded due to duplication, leaving 107 articles for further review. Of these, 63 full-length articles met the inclusion criteria and were included in the analyses. Most of the patients were male and exhibited elevated liver function tests (93.8%). Magnetic resonance imaging revealed duct thickening with contrast enhancement (47.7%), as well as beading of the intrahepatic ducts (45.7%) with peribiliary contrast enhancement on diffusion (28.7%). Liver biopsy results confirmed SC in most cases (74.4%). Sixteen patients underwent liver transplantation, with three experiencing successful outcomes.

CONCLUSION

Post-COVID-19 cholangiopathy is a serious condition that is expected to become increasingly concerning in the coming years, particularly considering long COVID syndromes. Although liver transplantation has been proposed as a potential treatment option, more research is necessary to establish its efficacy and explore other potential treatments.

Post-COVID-19 cholangiopathy: A systematic review

BACKGROUND

The recent and still ongoing pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entailed various long-term complications, including post-infectious cholangiopathy.

AIM

To identify the available studies concerning post-coronavirus disease 2019 (COVID-19) cholangiopathy.

METHODS

An extensive bibliographical search was carried out in PubMed and in Cochrane Library to identify the articles (retrospective and prospective studies, cohort studies, case series and case reports) published between January 1, 2020 and August 22, 2022, using both MeSH terms and free-language keywords: cholangiopathy; COVID-19; post-COVID-19 cholangiopathy; SARS-CoV-2.

RESULTS

Thirteen studies fulfilled the inclusion criteria, which included 64 patients suffering from this condition. The patients were male in 82.8% of cases. Liver transplant was executed in 6 patients and scheduled in 7 patients, while 2 patients refused the surgical approach. Therefore in 23.4% of the cases, performing this procedure appeared to be necessary.

CONCLUSION

This review has revealed that generally the involvement of the liver in the course of SARS-CoV-2 infection is mild and transient, inducing cholestasis of cholangiocytes but can also be severe enough to cause organ failure in some cases.

Post-COVID-19 cholangiopathy: Current understanding and management options

Post-coronavirus disease 2019 (COVID-19) cholangiopathy (PCC) is a rare but life-threatening complication of COVID-19 infection. PCC typically presents when patients recovering from the contagion and manifests as cholestasis in patients with no history of pre-existing liver disease. The pathogenesis of PCC is little understood. Hepatic injury in PCC could be mediated by the predilection of severe acute respiratory syndrome coronavirus 2 for cholangiocytes. Though PCC shows some resemblance to secondary sclerosing cholangitis in critically ill patients, it is considered as a separate and unique entity in the literature. Various treatment options like ursodeoxycholic acid, steroids, plasmapheresis, and endoscopic retrograde cholangiopancreatography guided interventions have been tried but with limited success. We have noticed significant improvement in liver function with antiplatelet therapy in a couple of patients. PCC can progress to end-stage liver disease necessitating liver transplantation. In this article, we discuss the current knowledge of PCC focusing on its pathophysiology, clinical manifestations, and management strategies.

Morphological aspects of small-duct cholangiopathies: A minireview

The biliary system consists of intrahepatic and extrahepatic bile ducts lined by biliary epithelial cells (cholangiocytes). Bile ducts and cholangiocytes are affected by a variety of disorders called cholangiopathies, which differ in aetiology, pathogenesis, and morphology. Classification of cholangiopathies is complex and reflects pathogenic mechanisms (immune-mediated, genetic, drug- and toxin-induced, ischaemic, infectious, neoplastic), predominant morphological patterns of biliary injury (suppurative and non-suppurative cholangitis, cholangiopathy), and specific segments of the biliary tree affected by the disease process. While the involvement of large extrahepatic and intrahepatic bile ducts is typically visualised using radiology imaging, histopathological examination of liver tissue obtained by percutaneous liver biopsy still plays an important role in the diagnosis of cholangiopathies affecting the small intrahepatic bile ducts. To increase the diagnostic yield of a liver biopsy and determine the optimal therapeutic approach, the referring clinician is tasked with interpreting the results of histopathological examination. This requires knowledge and understanding of basic morphological patterns of hepatobiliary injury and an ability to correlate microscopic findings with results obtained by imaging and laboratory methods. This minireview describes the morphological aspects of small-duct cholangiopathies pertaining to the diagnostic process.

Reversine attenuates cholestatic ductular reaction in rats

Ductular reaction (DR) is usually observed in biliary disorders or in various liver disorders, including non-alcoholic fatty liver disease. Few studies have focused on interrupting the DR process in the cholestatic environment. Here, we investigated the impact of reversine on DR in rats that had undergone bile duct ligation (BDL). Cholestatic injury was induced in rats two weeks following BDL. DR was assessed with biliary markers by immunohistochemistry. Biliary epithelial cells (BECs) were isolated for analysis of proliferation and biliary factor gene expression. The effects of reversine on DR and fibrosis were analyzed in vivo via intraperitoneal injection in rats for two weeks. Chemically-induced BEC formation was used to investigate the biliary markers affected by reversine in vitro. DR with increased BEC expansion was identified in cholestatic liver injury, as indicated by CK7, CK19, and EpCAM expression around the portal vein in BDL rats. BDL-induced DR cells showed increased expression of genes regulating cell proliferation (Ki67, Foxm1, and Pcna) and biliary markers (Krt7, Krt19, Epcam, Sox9, Cftr, and Asbt). Reversine attenuated cholestatic fibrosis and DR in rats. Reversine affected chemically-induced BEC formation, with decreased expression of biliary Krt7, Cftr, and Ggt1 genes in vitro. BDL-induced Notch activation was attenuated upon reversine treatment in vivo, in part via the Notch/Sox9 pathway. In conclusion, reversine attenuated cholestatic ductular reaction and fibrosis in rats and reduced the bile duct formation associated with Dlk1/Notch/Sox9 signaling. Reversine may be regarded as a potential drug for cholangiopathies for preventing ductular reaction.

Post-COVID-19 cholangiopathy: A systematic review

BACKGROUND

The recent and still ongoing pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entailed various long-term complications, including post-infectious cholangiopathy.

AIM

To identify the available studies concerning post-coronavirus disease 2019 (COVID-19) cholangiopathy.

METHODS

An extensive bibliographical search was carried out in PubMed and in Cochrane Library to identify the articles (retrospective and prospective studies, cohort studies, case series and case reports) published between January 1, 2020 and August 22, 2022, using both MeSH terms and free-language keywords: cholangiopathy; COVID-19; post-COVID-19 cholangiopathy; SARS-CoV-2.

RESULTS

Thirteen studies fulfilled the inclusion criteria, which included 64 patients suffering from this condition. The patients were male in 82.8% of cases. Liver transplant was executed in 6 patients and scheduled in 7 patients, while 2 patients refused the surgical approach. Therefore in 23.4% of the cases, performing this procedure appeared to be necessary.

CONCLUSION

This review has revealed that generally the involvement of the liver in the course of SARS-CoV-2 infection is mild and transient, inducing cholestasis of cholangiocytes but can also be severe enough to cause organ failure in some cases.

COVID-19-associated secondary sclerosing cholangitis - A case series of 4 patients

We report a case series of four patients diagnosed with COVID-19-associated secondary sclerosing cholangitis (SSC), a recently described rare late complication of severe COVID-19. Following prolonged stays in the intensive care unit, these patients developed marked sustained cholestasis and jaundice despite clinical improvement. Cholangiography showed beaded appearance of intra-hepatic bile ducts and bile casts were removed in one patient. None of the patients reached normalization of liver enzymes and at least one progressed to liver cirrhosis (follow-up time of 11 to 16 months). COVID-19-associated SSC has a dismal prognosis with rapid progression to advanced chronic liver disease.

Cholestatic liver injury: A rare but fatal complication during and after COVID-19 infection

The 2019 coronavirus disease (COVID-19), resulting from the severe acute respiratory syndrome 2 virus, has transformed our globe and provided a new perspective on respiratory tract infections. However, COVID-19 would not be recognized as a condition restricted to only pneumonia. This narrative review was conducted by searching manuscripts in several databases, including PubMed/ MEDLINE, Web of Science, and Reference Citation Analysis, from December 2019 to July 2022. Many studies have revealed a broad spectrum of potential systemic symptoms, including biliary complications. Although biliary injury has been observed in a very low proportion of COVID-19 patients, it is associated with increased mortalities and long-term morbidities. We identify a cholangiopathy condition in individuals during infection and after recovering from severe COVID-19, defined by a significant increase in serum alkaline phosphatase and signs of bile duct injury. Understanding the pathogeneses behind this condition would help us develop new techniques to prevent these complications. This review thoroughly discusses and summarizes the current information regarding COVID-19-associated cholangiopathy. In addition, the possible explanations for COVID-19-associated cholangiopathy are presented. Since the exact pathogenesis may not be concluded, this review could provide relevant information to encourage additional investigations shortly.

Post-Covid- 19 Cholangiopathy:A Systematic Review

OBJECTIVES

Post COVID-19 cholangiopathy is a rare but poorly understood and serious complication of COVID-19 infection. We sought to better understand the epidemiology, mechanism of action, histology, imaging findings and outcomes of post-COVID-19 cholangiopathy.

METHODS

We searched PubMed, Cochrane Library, Embase, and Web of Science from December 2019 to December 2021. Mesh words used "post-Covid-19 cholangiopathy", "COVID-19 liver injury"," Covid-19 and cholangiopathy", and COVID-19 liver disease". The data on epidemiology, mechanism of action, histology, imaging findings and outcomes were collected.

RESULTS

Post COVID-19 cholangiopathy was reported in 30 cases during the study period. The mean (standard deviation [SD]) age was 53.7 (5). Men accounted for cases (83.3%). All patients had required intensive level of care and mechanical ventilation. Mean (SD) number of days from COVID infection to severe disease or liver disease was 63.5(38). Peak mean (SD) alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, total bilirubin were 2014 (831.8) U/L, 1555 (2432.8) U/L, 899.72 (1238.6) U/L, and 10.32 (9.32) mg/dl, respectively. Four patients successfully underwent liver transplantation.

CONCLUSION

Post COVID-19 cholangiopathy is a severe and progressive complication of COVID-19 infection. More research is needed to better understand the pathophysiology and best treatment approach. Clinicians should suspect post COVID-19 cholangiopathy in patients with cholestatic liver injury following COVID-19 infection.

Role of ductular reaction and ductular-canalicular junctions in identifying severe primary biliary cholangitis

Background & Aims

Primary biliary cholangitis (PBC) is a chronic cholangiopathy characterised by immuno-mediated injury of interlobular bile ducts leading to intrahepatic cholestasis and progressive liver fibrosis. PBC histology is characterised by portal inflammation, progressive fibrosis, ductopenia, and the appearance of the so-called ductular reaction. The aim of the present study was to investigate the pathogenetic relevance of ductular reaction in PBC.

Methods

Liver biopsies were collected from naïve people with PBC (N = 87). Clinical-serological parameters were obtained at diagnosis and after 1 year of ursodeoxycholic acid (UDCA) treatment. Histological staging was performed on all slides according to multiple scoring systems and criteria for PBC. Liver samples were obtained from Mdr2 ^-/- mice treated with or without UDCA. Samples were processed for histology, immunohistochemistry, and immunofluorescence.

Results

Ductular reaction in people with PBC correlated with the disease stage and liver fibrosis, but not with disease activity; an extensive ductular reaction correlated with serum alkaline phosphatase levels at diagnosis, response to UDCA, and individuals' estimated survival, independently from other histological parameters, including disease stage. In people with PBC, reactive ductules were associated with the establishment of junctions with bile canaliculi and with fibrogenetic cell activation. Consistently, in a mouse model of intrahepatic cholestasis, UDCA treatment was effective in reducing ductular reaction and fibrosis and increasing ductular-canalicular junctions.

Conclusions

Extensive ductular reaction outlines a severe histologic phenotype in PBC and is associated with an inadequate therapy response and a worse estimated prognosis.

Lay summary

In people affected by primary biliary cholangitis (PBC), the histological appearance of extensive ductular reaction identifies individuals at risk of progressive fibrosis. Ductular reaction at diagnosis correlates with the lack of response to first-line therapy with ursodeoxycholic acid and serves to restore ductular-canalicular junctions in people with PBC. Assessing ductular reaction extension at diagnosis may add valuable information for clinicians.

Role of biliary complications in chronic graft rejection after living donor liver transplantation

Postoperative biliary complications remain a substantial challenge after living donor liver transplantation, especially due to its heterogeneous clinical presentation.

Long-term ketamine infusion-induced cholestatic liver injury in COVID-19-associated acute respiratory distress syndrome

Background

A higher-than-usual resistance to standard sedation regimens in COVID-19 patients suffering from acute respiratory distress syndrome (ARDS) has led to the frequent use of the second-line anaesthetic agent ketamine. Simultaneously, an increased incidence of cholangiopathies in mechanically ventilated patients receiving prolonged infusion of high-dose ketamine has been noted. Therefore, the objective of this study was to investigate a potential dose–response relationship between ketamine and bilirubin levels.

Methods

Post hoc analysis of a prospective observational cohort of patients suffering from COVID-19-associated ARDS between March 2020 and August 2021. A time-varying, multivariable adjusted, cumulative weighted exposure mixed-effects model was employed to analyse the exposure–effect relationship between ketamine infusion and total bilirubin levels.

Results

Two-hundred forty-three critically ill patients were included into the analysis. Ketamine was infused to 170 (70%) patients at a rate of 1.4 [0.9–2.0] mg/kg/h for 9 [4–18] days. The mixed-effects model revealed a positively correlated infusion duration–effect as well as dose–effect relationship between ketamine infusion and rising bilirubin levels (p < 0.0001). In comparison, long-term infusion of propofol and sufentanil, even at high doses, was not associated with increasing bilirubin levels (p = 0.421, p = 0.258). Patients having received ketamine infusion had a multivariable adjusted competing risk hazard of developing a cholestatic liver injury during their ICU stay of 3.2 [95% confidence interval, 1.3–7.8] (p = 0.01).

Conclusions

A causally plausible, dose–effect relationship between long-term infusion of ketamine and rising total bilirubin levels, as well as an augmented, ketamine-associated, hazard of cholestatic liver injury in critically ill COVID-19 patients could be shown. High-dose ketamine should be refrained from whenever possible for the long-term analgosedation of mechanically ventilated COVID-19 patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04019-8.

Diagnostic, therapeutic and prognostic challenges in a jaundiced patient treated with a checkpoint inhibitor

Immune check point inhibitors (CPI) are now standard treatment for numerous metastatic malignancies. They are associated with hepatological adverse reactions, the most common of which is immune related hepatitis (irH). Bile duct injury is rarely described. We present the case of a 42 year old male with metastatic non-small cell lung cancer (NSCLC) treated with atezolizumab who developed severe liver dysfunction with biochemical and radiological features of a cholangiopathy. Establishing the final diagnosis proved exceptionally difficult due to multiple potential aetiologies. In this article the diagnostic, prognostic and management challenges including the role of liver biopsy, biliary drainage and immune suppression are explored. Cholangiopathy related to CPI is an emerging clinical entity that requires coordinated, expert care and further research.

Hepatobiliary and Pancreatic Adverse Events

The expanded approval of immune checkpoint inhibitors (ICIs) for the treatment of multiple cancer types has offered patients more opportunities in treatment selection and survival.Hepatotoxicity is a well-recognized immune-related adverse event (irAE) associated with treatment with ICI. It is considered a type of drug-induced liver injury (DILI). Depending on the specific ICI and whether the patient receives single- or dual-drug therapy, the incidence of hepatotoxicity in general could be as high as 30%. As more patients receive treatment with ICI, more cases of hepatotoxicity are expected to occur. Clinicians must exercise close pharmacovigilance to recognize liver-related irAEs early.ICI-mediated hepatobiliary toxicity (or "IMH") generally presents as asymptomatic elevations of alanine transaminase and aspartate transaminase, with or without alkaline phosphatase elevation. Some patients may present with jaundice, fever, or malaise. Rarely, it may cause liver failure and death. The diagnosis of IMH is made after careful exclusion of other causes of acute hepatitis based on medical history, laboratory evaluation, imaging, and liver histological findings. In clinically significant cases of IMH, the management involves discontinuation of ICI followed by close monitoring and the initiation of immunosuppression. Current society guidelines, which are not based on robust evidence, specify treatment recommendations depending on the grade of liver injury, according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. However, our clinical experience suggests possible alternatives, including lower corticosteroid dosing with adjunct therapies. Whereas current guidelines endorse permanent cessation of future ICI treatment in patients diagnosed with grades 3-4 IMH, published clinical experience suggests potential for flexibility when assessing for candidacy of resuming ICI.Because histologic bile duct injury has been observed in cases ascribed to IMH, ICI-mediated cholangiopathic disease probably exists on a spectrum within IMH. Even extrahepatic bile duct involvement has been observed. This phenotype warrants special considerations in treatment and surveillance.ICI-related cholecystitis has been rarely reported in the literature. Management follows current standards of care for typical cases of cholecystitis. No relationship with ICI-mediated cholangiopathic disease has been observed.Assessing for and managing ICI-associated pancreatic injury remain challenging to the clinician. Many cases of asymptomatic serum lipase elevation are detected on routine labs without clinical signs or symptoms of typical acute pancreatitis. However, symptomatic patients should be initially managed like traditional cases of acute pancreatitis requiring hospitalization for evaluation and inpatient management.

Bile Duct-on-a-Chip

Cholangiopathies affect the biliary tree via various pathophysiological mechanisms. Research on biliary physiology and pathology, however, is hampered by a lack of physiologically relevant in vitro models. Conventional models, such as two-dimensional (2D) monolayers and organoids, fail to replicate the structural organization of the bile duct, and both the size of the duct and position of cells are difficult to manipulate in a controllable way. Here, we describe a bile duct-on-a-chip (BDOC) that phenocopies the open-ended tubular architecture of the bile duct in three dimensions which, when seeded with either a cholangiocyte cell line or primary cells, demonstrates barrier function similar to bile ducts in vivo. This device represents an in vitro platform to study the pathophysiology of the bile duct using cholangiocytes from a variety of sources.

Biliary Atresia - emerging diagnostic and therapy opportunities

Biliary Atresia is a devastating pediatric cholangiopathy affecting the bile ducts of the liver. In this review, we describe recent progress in the understanding of liver development with a focus on cholangiocyte differentiation and how use of technical platforms, including rodent, zebrafish and organoid models, advances our understanding of Biliary Atresia. This is followed by a description of potential pathomechanisms, such as autoimmune responses, inflammation, disturbed apical-basal cell polarity, primary cilia dysfunction as well as beta-amyloid accumulation. Finally, we describe current and emerging diagnostic opportunities and recent translation breakthroughs for Biliary Atresia in the area of emerging therapy development, including immunomodulation and organoid-based systems for liver and bile duct repair.

Cholangiopathy as part of post-COVID syndrome

Liver compromise in critically ill patients with coronavirus disease 2019 (COVID-19) is common but usually transient and self-limited. However, liver tests on some patients continue to show abnormal results. Herein, a 29-year-old patient with clinical and histological features of cholangiopathy is presented. Despite treatment with ursodeoxycholic acid and cholestyramine, bilirubin and transaminase levels remained elevated. This case report raises awareness of the difficulty of managing this condition in patients with COVID-19.

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Liver compromise in coronavirus disease 2019 (COVID-19) is common.

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Cholangiopathy must be consider as a clinical manifestation of post-COVID syndrome.

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Autoimmune liver compromise should be suspected in patients with transaminitis and hyperbilirubinemia.

A case of secondary sclerosing cholangitis due to COVID-19

COVID-19 was first recognized by the World Health Organization (WHO) in December 2019 and declared a global pandemic in March 2020. Although COVID-19 primarily results in pulmonary symptoms, it is becoming apparent that it can lead to multisystemic manifestations. Liver damage with elevated AST and ALT is seen in patients with COVID-19. Although the etiology of liver damage is still debated, biliary damage is rarely seen. This case demonstrates a potential complication of COVID-19 in a previously healthy patient. The patient contracted COVID-19 in March 2020 and endured a complicated course including intubation, multiple readmissions, and chronic abdominal pain. He is now awaiting a liver transplant. Our case portrays biliary damage as an additional possible complication of COVID-19 and the importance of imaging in its diagnosis.

Common ABCB4 and ABCB11 Genotypes Are Associated with Idiopathic Chronic Cholestasis in Adults

INTRODUCTION

Pathogenic mutations in genes encoding the hepatocanalicular transporters ATP8B1, ABCB11 and ABCB4 are causative for progressive cholestatic liver disease in children. In adults, less severe variants such as the common ABCB4 c.711A>T polymorphism have been associated with intrahepatic cholestasis in pregnancy and elevated liver enzymes. Hence, our aim was to study the role of common polymorphisms in adult patients with chronic unexplained cholestasis.

METHODS

Screening of outpatients of two university hospitals identified a cohort of 94 patients with chronic cholestasis of unknown origin after thorough exclusion of other causes. Genotyping was performed using TaqMan assays, and frequencies for the ABCB4 rs2109505 (c.711A>T), rs1202283 (c.504T>C), ABCB11 rs2287622 (p.A444V) and rs497692 (c.3084A>G) variants of the study cohort were compared to a cohort of 254 healthy controls.

RESULTS

The dominating symptoms of the patients were pruritus and jaundice, though the majority of them did not report symptoms at inclusion. Advanced fibrosis or cirrhosis was present in 11 patients (11.7%) only. Genotyping revealed the presence of the ABCB4 c.711A>T risk variant in 79 patients (84%), a frequency that is significantly (p = 0.037) higher than that in controls (71%). The ABCB11 p.A444V variant was also more frequent in cholestatic patients (p = 0.042).

CONCLUSION

The common ABCB4 c.711A>T and ABCB11 p.A444V polymorphisms are more prevalent in adult patients with idiopathic cholestasis than in healthy controls and may therefore represent risk factors for the development of chronic cholestatic liver disease.

Synthetic human ABCB4 mRNA therapy rescues severe liver disease phenotype in a BALB/c.Abcb4-/- mouse model of PFIC3

BACKGROUND & AIMS

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a rare lethal autosomal recessive liver disorder caused by loss-of-function variations of the ABCB4 gene, encoding a phosphatidylcholine transporter (ABCB4/MDR3). Currently, no effective treatment exists for PFIC3 outside of liver transplantation.

METHODS

We have produced and screened chemically and genetically modified mRNA variants encoding human ABCB4 (hABCB4 mRNA) encapsulated in lipid nanoparticles (LNPs). We examined their pharmacological effects in a cell-based model and in a new in vivo mouse model resembling human PFIC3 as a result of homozygous disruption of the Abcb4 gene in fibrosis-susceptible BALB/c.Abcb4-/- mice.

RESULTS

We show that treatment with liver-targeted hABCB4 mRNA resulted in de novo expression of functional hABCB4 protein and restored phospholipid transport in cultured cells and in PFIC3 mouse livers. Importantly, repeated injections of the hABCB4 mRNA effectively rescued the severe disease phenotype in young Abcb4-/- mice, with rapid and dramatic normalisation of all clinically relevant parameters such as inflammation, ductular reaction, and liver fibrosis. Synthetic mRNA therapy also promoted favourable hepatocyte-driven liver regeneration to restore normal homeostasis, including liver weight, body weight, liver enzymes, and portal vein blood pressure.

CONCLUSIONS

Our data provide strong preclinical proof-of-concept for hABCB4 mRNA therapy as a potential treatment option for patients with PFIC3.

LAY SUMMARY

This report describes the development of an innovative mRNA therapy as a potential treatment for PFIC3, a devastating rare paediatric liver disease with no treatment options except liver transplantation. We show that administration of our mRNA construct completely rescues severe liver disease in a genetic model of PFIC3 in mice.

Primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a rare chronic cholestatic liver disease characterized by inflammatory destruction of the intrahepatic and/or extrahepatic bile ducts, leading to bile stasis, fibrosis, and ultimately to cirrhosis, and often requires liver transplantation (LT). PSC occurs more commonly in men, and is typically diagnosed between the ages of 30 and 40. Most cases occur in association with inflammatory bowel disease (IBD), which often precedes the development of PSC. PSC is usually diagnosed after detection of cholestasis during health evaluation or screening of patients with IBD. When symptomatic, the most common presenting symptoms are abdominal pain, pruritus, jaundice or fatigue. The etiology of PSC is poorly understood, but an increasing body of evidence supports the concept of cholangiocyte injury as a result of environmental exposure and an abnormal immune response in genetically susceptible individuals. PSC is a progressive disease, yet no effective medical therapy for halting disease progression has been identified. Management of PSC is mainly focused on treatment of symptoms and addressing complications. PSC can be complicated by bacterial cholangitis, dominant strictures (DSs), gallbladder polyps and adenocarcinoma, cholangiocarcinoma (CCA) and, in patients with IBD, colorectal malignancy. CCA is the most common malignancy in PSC with a cumulative lifetime risk of 10-20%, and accounts for a large proportion of mortality in PSC. LT is currently the only life-extending therapeutic approach for eligible patients with end-stage PSC, ultimately required in approximately 40% of patients. LT secondary to PSC has an excellent outcome compared to other LT indications, although the disease can recur and result in morbidity post-transplant.

Recreational ketamine-induced cholangiopathy and ulcerative cystitis

Ketamine is a versatile analgesic that has become an increasingly popular recreational drug. Chronic ketamine use has been found to cause biliary duct damage and bladder dysfunction. Ketamine-induced cholangiopathy and ulcerative cystitis are uncommon diagnoses presenting with nonspecific symptoms, creating diagnostic challenges for emergency physicians. We report a case of a teenage patient with the rare simultaneous presentation of ketamine-induced cholangiopathy and ulcerative cystitis. Due to increased recreational and chronic ketamine use, cases of ketamine-induced cholangiopathy and ulcerative cystitis are likely to rise with the increased knowledge, awareness, and reporting of these entities by radiologists and emergency physicians.

Beta-amyloid deposition around hepatic bile ducts is a novel pathobiological and diagnostic feature of biliary atresia

BACKGROUND AND AIMS

Biliary atresia (BA) is a poorly understood and devastating obstructive bile duct disease of newborns. It is often diagnosed late, is incurable and frequently requires liver transplantation. In this study, we aimed to investigate the underlying pathogenesis and molecular signatures associated with BA.

METHODS

We combined organoid and transcriptomic analysis to gain new insights into BA pathobiology using patient samples and a mouse model of BA.

RESULTS

Liver organoids derived from patients with BA and a rhesus rotavirus A-infected mouse model of BA, exhibited aberrant morphology and disturbed apical-basal organization. Transcriptomic analysis of BA organoids revealed a shift from cholangiocyte to hepatocyte transcriptional signatures and altered beta-amyloid-related gene expression. Beta-amyloid accumulation was observed around the bile ducts in BA livers and exposure to beta-amyloid induced the aberrant morphology in control organoids.

CONCLUSION

The novel observation that beta-amyloid accumulates around bile ducts in the livers of patients with BA has important pathobiological implications, as well as diagnostic potential.

LAY SUMMARY

Biliary atresia is a poorly understood and devastating obstructive bile duct disease of newborns. It is often diagnosed late, is incurable and frequently requires liver transplantation. Using human and mouse 'liver mini-organs in the dish', we unexpectedly identified beta-amyloid deposition - the main pathological feature of Alzheimer's disease and cerebral amyloid angiopathy - around bile ducts in livers from patients with biliary atresia. This finding reveals a novel pathogenic mechanism that could have important diagnostic and therapeutic implications.

Tissue engineering of the biliary tract and modelling of cholestatic disorders

Our insight into the pathogenesis of cholestatic liver disease remains limited, partly owing to challenges in capturing the multitude of factors that contribute to disease pathogenesis in vitro. Tissue engineering could address this challenge by combining cells, materials and fabrication strategies into dynamic modelling platforms, recapitulating the multifaceted aetiology of cholangiopathies. Herein, we review the advantages and limitations of platforms for bioengineering the biliary tree, looking at how these can be applied to model biliary disorders, as well as exploring future directions for the field.

Obstructive cholangiopathy patient caused by cytomegalovirus and Kaposi sarcoma in a person living with HIV and hepatitis C

We present the case of a 28-year-old man with recently-diagnosed human immunodeficiency virus and hepatitis C virus infection. He developed obstructive cholangiopathy secondary to cytomegalovirus and Kaposi sarcoma, both diagnosed by endoscopic retrograde cholangiopancreatography and biopsies. He received antiretroviral therapy, chemotherapy and valganciclovir with full recovery.

Mouse Models for Diseases in the Cholangiocyte Lineage

Cholangiopathies are an important group of liver diseases affecting the biliary system, and the purpose of this review is to describe how diseases in the biliary system can be studied in mouse models. A particular focus is placed on mouse models for Alagille syndrome, a cholangiopathy with a strong genetic link to dysfunctional Notch signaling. Recently, a number of different genetic mouse models based on various manipulations of the Notch signaling pathway have been generated to study Alagille syndrome, and we discuss the resulting phenotypes, and possible causes for the phenotypic heterogeneity among the various models. In the final section, we provide a more general discussion on how well mouse models can be expected to mimic human liver disease, as well as an outlook toward the need for new technologies that can help us to gain new insights from mouse models for liver disease.

Preclinical insights into cholangiopathies: disease modeling and emerging therapeutic targets

INTRODUCTION

The common predominant clinical features of cholangiopathies such as primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC), and biliary atresia (BA) are biliary damage/senescence and liver fibrosis. Curative therapies are lacking, and liver transplantation is the only option. An understanding of the mechanisms and pathogenesis is needed to develop novel therapies. Previous studies have developed various disease-based research models and have identified candidate therapeutic targets. Areas covered: This review summarizes recent studies performed in preclinical models of cholangiopathies and the current understanding of the pathophysiology representing potential targets for novel therapies. A literature search was conducted in PubMed using the combination of the searched term 'cholangiopathies' with one or two keywords including 'model', 'cholangiocyte', 'animal', or 'fibrosis'. Papers published within five years were obtained. Expert opinion: Access to appropriate research models is a key challenge in cholangiopathy research; establishing more appropriate models for PBC is an important goal. Several preclinical studies have demonstrated promising results and have led to novel therapeutic approaches, especially for PSC. Further studies on the pathophysiology of PBC and BA are necessary to identify candidate targets. Innovative therapeutic approaches such as stem cell transplantation have been introduced, and those therapies could be applied to PSC, PBC, and BA.

Primary Sclerosing Cholangitis: A Concise Review of Diagnosis and Management

Primary sclerosing cholangitis is a rare, chronic cholestatic liver disease characterized by progressive idiopathic stricturing of the biliary system, typically leading to cirrhosis, end-stage liver disease, and colonic or hepatobiliary malignancy. Its presentation is often that of asymptomatic alkaline phosphatase elevation. When symptoms are present, they typically include fatigue, pruritus, or jaundice. The diagnosis can be confirmed via cholangiography, either magnetic resonance cholangiography (MRCP) or endoscopic retrograde cholangiography if the former is inconclusive. The clinical course is marked by progressive liver disease leading to cirrhosis with its attendant complications of portal hypertension, often including recurrent episodes of cholangitis. Greater elevation in alkaline phosphatase or liver stiffness is associated with worse clinical outcomes. Management includes endoscopic treatment of symptomatic biliary strictures and evaluation of dominant strictures as no adequate medical treatment is available. Multiple medical therapies are under evaluation. Ultimately, liver transplantation may be necessary for management of decompensated cirrhosis or disabling symptoms. There is also a markedly increased risk of cancer, notably including cholangiocarcinoma and gallbladder and colorectal cancers (particularly in patients with colitis). Cancer screening can be done with semi-annual liver imaging (MRCP or ultrasound) and colonoscopy every 1-2 years in those with colitis.

Lysyl oxidase-like protein 2 (LOXL2) modulates barrier function in cholangiocytes in cholestasis

BACKGROUND & AIMS

The lysyl oxidase-like protein 2 (LOXL2) promotes stabilization of the extracellular matrix, chemotaxis, cell growth and cell mobility. We aimed to (i) identify stimuli of LOXL2 in cholangiopathies, (ii) characterize the effects of LOXL2 on biliary epithelial cells' (BECs) barrier function, (iii) compare LOXL2 expression in primary sclerosing cholangitis (PSC), primary biliary cholangitis, and disease controls, and (iv) to determine LOXL2 expression and its cellular sources in four mouse models of cholangiopathies.

METHODS

Cultured murine BECs were challenged with well-known triggers of cellular senescence, hypoxia, phospholipid-deficient Abcb4^-/- mouse bile and chenodeoxycholic acid and investigated for LOXL2, SNAIL1 and E-cadherin expression and transepithelial electrical resistance with and without LOX-inhibition. In vivo, LOXL2 expression was studied in PSC livers, and controls and mouse models. We compared LOXL2 serum levels in patients with PSC, secondary SC, primary biliary cholangitis, and controls.

RESULTS

Cellular senescence, hypoxia, Abcb4^-/- bile and chenodeoxycholic acid induced LOXL2 and SNAIL1 expression, repressed E-cadherin expression, and significantly reduced transepithelial electrical resistance in BECs. Notably, all of the pathological changes could be recovered via pharmacological LOX-inhibition. Mouse models showed induced LOXL2 expression in the portal region and in association with ductular reaction. LOXL2 serum levels were significantly elevated in patients with cholangiopathies. In PSC, LOXL2 expression was located to characteristic periductal onion skin-type fibrosis, ductular reaction, Kupffer cells, and fibrotic septa. Importantly, in PSC, LOXL2 overexpression was paralleled by E-cadherin loss in BECs from medium-sized bile ducts.

CONCLUSIONS

Reactive BECs produce LOXL2, resulting in increased tight junction permeability, which can be ameliorated by pharmacological LOX-inhibition in vitro. Reactive BECs, portal myofibroblasts, and Kupffer cells are the main sources of LOXL2 in cholangiopathies.

LAY SUMMARY

In this study, we investigate the role of lysyl oxidase-like protein 2 (LOXL2), an enzyme pivotal in the development of organ fibrosis, in the pathogenesis of cholangiopathies (diseases of bile ducts), such as primary sclerosing cholangitis. We found LOXL2 to be expressed in association with bile duct epithelial injury and uncovered mechanisms for its upregulation and the subsequent effects in vitro and in vivo. Our findings support testing of anti-LOXL2 treatment strategies for patients with primary sclerosing cholangitis.

Nodular macroregenerative tissue as a pattern of regeneration in cholangiopathic disorders

BACKGROUND

Published case series have described central hepatic macroregenerative nodules or masses as a common feature of Alagille syndrome. Our experience suggests this regenerative pattern can be seen more generally in cholangiopathic disorders.

OBJECTIVE

To define the frequency of central regenerative tissue in Alagille syndrome and other cholangiopathic disorders and to describe the typical appearance of such regenerative tissue.

MATERIALS AND METHODS

We conducted a retrospective study of CT and MR imaging performed in children and young adults with cholangiopathic disorders between January 2000 and June 2016. Two pediatric radiologists reviewed images in consensus for the presence and features of macroregenerative tissue. Tissue histopathology, when available, was retrieved from the medical record.

RESULTS

Of 226 patients with cholangiopathic disorders, 23% (52/226) had macroregenerative tissue, and this tissue was central in 96% (50/52). Tissue was well defined and mass-like in 38% (20/52). Regenerative tissue was most common among the subset of patients with Langerhans cell histiocytosis with hepatic involvement (71%, 5/7) and was identified in 43% (16/37) of patients with Alagille syndrome. Regenerative tissue was iso- to hyperintense on T1-weighted MR sequences in 96% (50/52) of cases and hypointense on T2-weighted MR imaging in 94% (48/51). Arterial phase hyperenhancement was present in only five patients (12% of 43), none of whom showed portal venous phase washout. Histopathology was available for 20 cases, all showing benign regenerative tissue.

CONCLUSION

Central mass-like regeneration appears to be a common regenerative pattern in cholangiopathic disorders and should not be mistaken for malignancy.

The pathophysiology of human obstructive cholestasis is mimicked in cholestatic Gold Syrian hamsters

Obstructive cholestasis causes liver injury via accumulation of toxic bile acids (BAs). Therapeutic options for cholestatic liver disease are limited, partially because the available murine disease models lack translational value. Profiling of time-related changes following bile duct ligation (BDL) in Gold Syrian hamsters revealed a biochemical response similar to cholestatic patients in terms of BA pool composition, alterations in hepatocyte BA transport and signaling, suppression of BA production, and adapted BA metabolism. Hamsters tolerated cholestasis well for up to 28days and progressed relatively slowly to fibrotic liver injury. Hepatocellular necrosis was absent, which coincided with preserved intrahepatic energy levels and only mild oxidative stress. The histological response to cholestasis in hamsters was similar to the changes seen in 17 patients with prolonged obstructive cholestasis caused by cholangiocarcinoma. Hamsters moreover upregulated hepatic fibroblast growth factor 15 (Fgf15) expression in response to BDL, which is a cytoprotective adaptation to cholestasis that hitherto had only been documented in cholestatic human livers. Hamster models should therefore be added to the repertoire of animal models used to study the pathophysiology of cholestatic liver disease.

Advances in the generation of bioengineered bile ducts

The generation of bioengineered biliary tissue could contribute to the management of some of the most impactful cholangiopathies associated with liver transplantation, such as biliary atresia or ischemic cholangiopathy. Recent advances in tissue engineering and in vitro cholangiocyte culture have made the achievement of this goal possible. Here we provide an overview of these developments and review the progress towards the generation and transplantation of bioengineered bile ducts. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni and Peter Jansen.

Drug-induced bile duct injury

Drug-induced liver injury includes a spectrum of pathologies, some related to the mode of injury, some to the cell type primarily damaged. Among these, drug-induced bile duct injury is characterized by the destruction of the biliary epithelium following exposure to a drug. Most of the drugs associated with bile duct injury cause immune-mediated lesions to the epithelium of interlobular ducts. These share common histopathological features with primary biliary cholangitis, such as inflammation and necrosis at the expense of cholangiocytes and, if the insult persists, bile duct loss and biliary cirrhosis. Some drugs selectively target larger ducts. Such injury is often dose-dependent and thought to be the result of intrinsic drug toxicity. The histological changes resemble those seen in primary sclerosing cholangitis. This overview focuses on the clinical and pathological features of bile duct injury associated with drug treatment and on the immunological and biochemical effects that drugs exert on the biliary epithelium. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Biology of Cholangiocytes: From Bench to Bedside

Cholangiocytes, the lining epithelial cells in bile ducts, are an important subset of liver cells. They are activated by endogenous and exogenous stimuli and are involved in the modification of bile volume and composition. They are also involved in damaging and repairing the liver. Cholangiocytes have many functions including bile production. They are also involved in transport processes that regulate the volume and composition of bile. Cholangiocytes undergo proliferation and cell death under a variety of conditions. Cholangiocytes have functional and morphological heterogenecity. The immunobiology of cholangiocytes is important, particularly for understanding biliary disease. Secretion of different proinflammatory mediators, cytokines, and chemokines suggests the major role that cholangiocytes play in inflammatory reactions. Furthermore, paracrine secretion of growth factors and peptides mediates extensive cross-talk with other liver cells, including hepatocytes, stellate cells, stem cells, subepithelial myofibroblasts, endothelial cells, and inflammatory cells. Cholangiopathy refers to a category of chronic liver diseases whose primary disease target is the cholangiocyte. Cholangiopathy usually results in end-stage liver disease requiring liver transplant. We summarize the biology of cholangiocytes and redefine the concept of cholangiopathy. We also discuss the recent progress that has been made in understanding the pathogenesis of cholangiopathy and how such progress has influenced therapy.

Mutations in DCDC2 (doublecortin domain containing protein 2) in neonatal sclerosing cholangitis

BACKGROUND & AIMS

Neonatal sclerosing cholangitis (NSC) is a severe neonatal-onset cholangiopathy commonly leading to liver transplantation (LT) for end-stage liver disease in childhood. Liver biopsy findings histopathologically resemble those in biliary atresia (BA); however, in NSC extrahepatic bile ducts are patent, whilst in BA their lumina are obliterated. NSC is commonly seen in consanguineous kindreds, suggesting autosomal recessive inheritance.

METHODS

From 29 NSC patients (24 families) identified, DNA was available in 24 (21 families). Thirteen (7 male) patients (12 families) of consanguineous parentage were selected for whole exome sequencing. Sequence variants were filtered for homozygosity, pathogenicity, minor allele frequency, quality score, and encoded protein expression pattern.

RESULTS

Four of 13 patients were homozygous and two were compound heterozygous for mutations in the doublecortin domain containing 2 gene (DCDC2), which encodes DCDC2 protein and is expressed in cholangiocyte cilia. Another 11 patients were sequenced: one (with one sibling pair) was compound heterozygous for DCDC2 mutations. All mutations were protein-truncating. In available liver tissue from patients with DCDC2 mutations, immunostaining for human DCDC2 and the ciliary protein acetylated alpha-tubulin (ACALT) showed no expression (n=6) and transmission electron microscopy found that cholangiocytes lacked primary cilia (n=5). DCDC2 and ACALT were expressed in NSC patients without DCDC2 mutations (n=22). Of the patients carrying DCDC2 mutations, one died awaiting LT; five came to LT, of whom one died 2years later. The other 4 are well.

CONCLUSION

Among 24 NSC patients with available DNA, 7 had mutations in DCDC2 (6 of 19 families). NSC patients in substantial proportion harbour mutations in DCDC2. Their disease represents a novel liver-based ciliopathy.

LAY SUMMARY

Neonatal sclerosing cholangitis (NSC) is a rare genetic form of liver disease presenting in infancy. Through next generation sequencing we identified mutations in the gene encoding for doublecortin domain containing 2 (DCDC2) protein in a group of NSC children. DCDC2 is a signalling and structural protein found in primary cilia of cholangiocytes. Cholangiocytes are the cells forming the biliary system which is the draining system of the liver.