Genetics and mechanisms of hepatic cystogenesis

Liver-specific DICER1 syndrome model mice develop cystic liver tumors with defective primary cilia

DICER1 syndrome is a tumor predisposition syndrome caused by familial genetic mutations in DICER1. Pathogenic variants of DICER1 have been discovered in many rare cancers, including cystic liver tumors. However, the molecular mechanisms underlying liver lesions induced by these variants remain unclear. In the present study, we sought to gain a better understanding of the pathogenesis of these variants by generating a mouse model of liver-specific DICER1 syndrome. The mouse model developed bile duct hyperplasia with fibrosis, similar to congenital hepatic fibrosis, as well as cystic liver tumors resembling those in Caroli's syndrome, intrahepatic cholangiocarcinoma, and hepatocellular carcinoma. Interestingly, the mouse model of DICER1 syndrome showed abnormal formation of primary cilia in the bile duct epithelium, which is a known cause of bile duct hyperplasia and cyst formation. These results indicated that DICER1 mutations contribute to cystic liver tumors by inducing defective primary cilia. The mouse model generated in this study will be useful for elucidating the potential mechanisms of tumorigenesis induced by DICER1 variants and for obtaining a comprehensive understanding of DICER1 syndrome. © 2024 The Pathological Society of Great Britain and Ireland.

Liver transplant recipients with polycystic liver disease have longer waiting times but better long-term clinical outcomes than those with liver disease due to other causes: A retrospective cross-sectional study

INTRODUCTION

Liver transplantation is the only curative option for patients with polycystic liver disease (PLD). In the United Kingdom, these patients are listed on the variant syndrome list due to their preserved liver function reflected in the United Kingdom End-stage Liver Disease (UKELD) score. The transplantation and survival rates for this patient group in the UK have not been previously reported.

METHODS

A retrospective cross-sectional analysis of patients receiving liver transplantation between 2010 and 2017 was performed using the NHS blood and transplantation database. This database contains the demographic, clinical parameters, indication for transplantation and follow-up of all patients in UK-based transplant centres. Basic statistics was performed using SPSS version 27.

RESULTS

5412 recipients received elective liver allografts in the study period. 1.6% (100) of recipients had PLD as their primary indication for transplantation with 60 receiving liver only allografts and 40 receiving combined liver-kidney allografts. PLD patients had a >3-fold longer mean waiting time for transplantation compared to non-PLD patients, 508 days v 154 days respectively. PLD patients receiving combined liver-kidney allografts had a longer waiting time than those receiving a liver only allograft, 610 days v 438 days respectively. There were comparable patient survival rates for people with PLD and non-PLD primary indications at 30 days (94.0% vs 97.6%) and 1 year (92.0% vs 93.2%) but improved survival rates at 5 years (81.3% vs 76.5%). There were also comparable allograft survival rates for people with PLD and non-PLD primary indications at 30 days (93.9% vs 95.3%) and 1 year (91.9% vs 91.2%) but improved survival rates at 5 years (82.5% vs 77.3%). Transplant centre-level analysis identified variation in the proportion of liver transplantations for people with PLD as their primary listed indication.

CONCLUSIONS

Patients with PLD wait significantly longer for liver transplantation compared to other indications. However, transplanted PLD patients demonstrate better longer-term patient and liver allograft survival rates compared to transplanted non-PLD patients. The unexpected variation between individual UK centres transplanting for PLD deserves further study.

Activation of ACLY by SEC63 deploys metabolic reprogramming to facilitate hepatocellular carcinoma metastasis upon endoplasmic reticulum stress

BACKGROUND

Tumor cells display augmented capability to maintain endoplasmic reticulum (ER) homeostasis and hijack ER stress pathway for malignant phenotypes under microenvironmental stimuli. Metabolic reprogramming is a well-known hallmark for tumor cells to provide specific adaptive traits to the microenvironmental alterations. However, it's unknown how tumor cells orchestrate metabolic reprogramming and tumor progression in response to ER stress. Herein, we aimed to explore the pivotal roles of SEC63-mediated metabolic remodeling in hepatocellular carcinoma (HCC) cell metastasis after ER stress.

METHODS

The expression levels of SEC63 in HCC tissues and adjacent non-cancerous tissues were determined by immunohistochemistry and western blot. The regulatory roles of SEC63 in HCC metastasis were investigated both in vitro and in vivo by RNA-sequencing, metabolites detection, immunofluorescence, and transwell migration/invasion analyses. GST pull-down, immunoprecipitation/mass spectrometry and in vivo ubiquitination/phosphorylation assay were conducted to elucidate the underlying molecular mechanisms.

RESULTS

We identified SEC63 as a new regulator of HCC cell metabolism. Upon ER stress, the phosphorylation of SEC63 at T537 by IRE1α pathway contributed to SEC63 activation. Then, the stability of ACLY was upregulated by SEC63 to increase the supply of acetyl-CoA and lipid biosynthesis, which are beneficial for improving ER capacity. Meanwhile, SEC63 also entered into nucleus for increasing nuclear acetyl-CoA production to upregulate unfolded protein response targets to improve ER homeostasis. Importantly, SEC63 coordinated with ACLY to epigenetically modulate expression of Snail1 in the nucleus. Consequently, SEC63 promoted HCC cell metastasis and these effects were reversed by ACLY inhibition. Clinically, SEC63 expression was significantly upregulated in HCC tissue specimens and was positively correlated with ACLY expression. Importantly, high expression of SEC63 predicted unfavorable prognosis of HCC patients.

CONCLUSIONS

Our findings revealed that SEC63-mediated metabolic reprogramming plays important roles in keeping ER homeostasis upon stimuli in HCC cells. Meanwhile, SEC63 coordinates with ACLY to upregulate the expression of Snail1, which further promotes HCC metastasis. Metastasis is crucial for helping cancer cells seek new settlements upon microenvironmental stimuli. Taken together, our findings highlight a cancer selective adaption to ER stress as well as reveal the potential roles of the IRE1α-SEC63-ACLY axis in HCC treatment.

Multi-omics profiling of cholangiocytes reveals sex-specific chromatin state dynamics during hepatic cystogenesis in polycystic liver disease

BACKGROUND & AIMS

Cholangiocytes transit from quiescence to hyperproliferation during cystogenesis in polycystic liver disease (PLD), the severity of which displays prominent sex differences. Epigenetic regulation plays important roles in cell state transition. We aimed to investigate the sex-specific epigenetic basis of hepatic cystogenesis and to develop therapeutic strategies targeting epigenetic modifications for PLD treatment.

METHODS

Normal and cystic primary cholangiocytes were isolated from wild-type and PLD mice of both sexes. Chromatin states were characterized by analyzing chromatin accessibility (ATAC sequencing) and multiple histone modifications (chromatin immunoprecipitation sequencing). Differential gene expression was determined by transcriptomic analysis (RNA sequencing). Pharmacologic inhibition of epigenetic modifying enzymes was undertaken in PLD model mice.

RESULTS

Through genome-wide profiling of chromatin dynamics, we revealed a profound increase of global chromatin accessibility during cystogenesis in both male and female PLD cholangiocytes. We identified a switch from H3K9me3 to H3K9ac on cis-regulatory DNA elements of cyst-associated genes and showed that inhibition of H3K9ac acetyltransferase or H3K9me3 demethylase slowed cyst growth in male, but not female, PLD mice. In contrast, we found that H3K27ac was specifically increased in female PLD mice and that genes associated with H3K27ac-gained regions were enriched for cyst-related pathways. In an integrated epigenomic and transcriptomic analysis, we identified an estrogen receptor alpha-centered transcription factor network associated with the H3K27ac-regulated cystogenic gene expression program in female PLD mice.

CONCLUSIONS

Our findings highlight the multi-layered sex-specific epigenetic dynamics underlying cholangiocyte state transition and reveal a potential epigenetic therapeutic strategy for male PLD patients.

IMPACT AND IMPLICATIONS

In the present study, we elucidate a sex-specific epigenetic mechanism underlying the cholangiocyte state transition during hepatic cystogenesis and identify epigenetic drugs that effectively slow cyst growth in male PLD mice. These findings underscore the importance of sex difference in the pathogenesis of PLD and may guide researchers and physicians to develop sex-specific personalized approaches for PLD treatment.

Primary hepatic myopericytoma coexisting with multiple cystic hepatic lesions: a case report

BACKGROUND

Hepatic myopericytoma (MPC) is an extremely rare pathological entity in the liver. Conversely, cystic hepatic lesions are a group of heterogeneous lesions encountered commonly in daily practice. Here, we report a unique case of the coexistence of primary hepatic MPC and multiple cystic hepatic lesions along with our perceptions on its diagnosis and treatment.

CASE PRESENTATION

A 56-year-old female patient was found to have a left liver mass during a routine physical examination. Computer tomography (CT) and magnetic resonance imaging (MRI) confirmed the existence of a left hepatic neoplasm along with multiple hepatic cysts but could not exclude the possible malignant nature of the neoplasm. Computer tomography (CT) also identified an enlarged mediastinal lymph node with a maximum diameter of 4.3 cm, which further underwent core needle biopsy under CT guidance. A histopathological examination was performed to rule out malignancy. Afterwards, the patient underwent left hemihepatectomy to resect a solid tumor of 5.5 cm × 5 cm × 4.7 cm with multiple cystic lesions which were histopathologically examined to establish the diagnosis of myopericytoma with hepatic cysts. Postoperatively, the patient recovered from the surgery quickly without significant adverse events and was not found to have a reoccurrence of the primary pathological entity.

CONCLUSIONS

This is the first reported case of a patient with the co-existence of primary hepatic myopericytoma and multiple cystic hepatic lesions undergoing surgical treatment with eventual recovery.

Polycystic Liver Disease: Pathophysiology, Diagnosis and Treatment

Polycystic liver disease (PLD) is a clinical condition characterized by the presence of more than 10 cysts in the liver. It is a rare disease Of genetic etiology that presents as an isolated disease or assoc\iated with polycystic kidney disease. Ductal plate malformation, ciliary dysfunction, and changes in cell signaling are the main factors involved in its pathogenesis. Most patients with PLD are asymptomatic, but in 2-5% of cases the disease has disabling symptoms and a significant reduction in quality of life. The diagnosis is based on family history of hepatic and/or renal polycystic disease, clinical manifestations, patient age, and polycystic liver phenotype shown on imaging examinations. PLD treatment has evolved considerably in the last decades. Somatostatin analogues hold promise in controlling disease progression, but liver transplantation remains a unique curative treatment modality.

Molecular Mechanisms of Isolated Polycystic Liver Diseases

Polycystic liver disease (PLD) is a rare autosomal dominant disorder including two genetically and clinically distinct forms: autosomal dominant polycystic kidney disease (ADPKD) and isolated polycystic liver disease (PCLD). The main manifestation of ADPKD is kidney cysts, while PCLD has predominantly liver presentations with mild or absent kidney cysts. Over the past decade, PRKCSH, SEC63, ALG8, and LRP5 have been candidate genes of PCLD. Recently, more candidate genes such as GANAB, SEC61B, and ALR9 were also reported in PCLD patients. This review focused on all candidate genes of PCLD, including the newly established novel candidate genes. In addition, we also discussed some other genes which might also contribute to the disease.

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.

Polycystic Liver Disease: Advances in Understanding and Treatment

Polycystic liver disease (PLD) is a group of genetic disorders characterized by progressive development of cholangiocyte-derived fluid-filled hepatic cysts. PLD is the most common manifestation of autosomal dominant and autosomal recessive polycystic kidney diseases and rarely occurs as autosomal dominant PLD. The mechanisms of PLD are a sequence of the primary (mutations in PLD-causative genes), secondary (initiation of cyst formation), and tertiary (progression of hepatic cystogenesis) interconnected molecular and cellular events in cholangiocytes. Nonsurgical, surgical, and limited pharmacological treatment options are currently available for clinical management of PLD. Substantial evidence suggests that pharmacological targeting of the signaling pathways and intracellular processes involved in the progression of hepatic cystogenesis is beneficial for PLD. Many of these targets have been evaluated in preclinical and clinical trials. In this review, we discuss the genetic, molecular, and cellular mechanisms of PLD and clinical and preclinical treatment strategies. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Liver Involvement in Congenital Disorders of Glycosylation: A Systematic Review

An ever-increasing number of disturbances in glycosylation have been described to underlie certain unexplained liver diseases presenting either almost isolated or in a multi-organ context. We aimed to update previous literature screenings which had identified up to 23 forms of congenital disorders of glycosylation (CDG) with associated liver disease. We conducted a comprehensive literature search of three scientific electronic databases looking at articles published during the last 20 years (January 2000-October 2020). Eligible studies were case reports/series reporting liver involvement in CDG patients. Our systematic review led us to point out 41 forms of CDG where the liver is primarily affected (n = 7) or variably involved in a multisystem disease with mandatory neurological abnormalities (n = 34). Herein we summarize individual clinical and laboratory presentation characteristics of these 41 CDG and outline their main presentation and diagnostic cornerstones with the aid of two synoptic tables. Dietary supplementation strategies have hitherto been investigated only in seven of these CDG types with liver disease, with a wide range of results. In conclusion, the systematic review recognized a liver involvement in a somewhat larger number of CDG variants corresponding to about 30% of the total of CDG so far reported, and it is likely that the number may increase further. This information could assist in an earlier correct diagnosis and a possibly proper management of these disorders.

JNK signaling prevents biliary cyst formation through a CASPASE-8-dependent function of RIPK1 during aging

JNK signaling has been studied intensively in models of liver physiology and disease, but previous studies had focused on young mice. However, it had not been recognized that JNK plays a fundamental role in maintaining liver homeostasis and preventing the formation of biliary cysts in aging mice. These observations call for caution in all long-term pharmacological inhibition strategies targeting the JNK pathway. Finally, our results provide evidence of a molecular link between JNK and the cell-death mediator RIPK1. The specific overexpression of RIPK1 in cysts of a subset of patients with polycystic liver disease suggests that RIPK1 might be mechanistically involved in the pathogenesis of human biliary cysts.

The c-Jun N-terminal kinase (JNK) signaling pathway mediates adaptation to stress signals and has been associated with cell death, cell proliferation, and malignant transformation in the liver. However, up to now, its function was experimentally studied mainly in young mice. By generating mice with combined conditional ablation of Jnk1 and Jnk2 in liver parenchymal cells (LPCs) (JNK1/2^LPC-KO mice; KO, knockout), we unraveled a function of the JNK pathway in the regulation of liver homeostasis during aging. Aging JNK1/2^LPC-KO mice spontaneously developed large biliary cysts that originated from the biliary cell compartment. Mechanistically, we could show that cyst formation in livers of JNK1/2^LPC-KO mice was dependent on receptor-interacting protein kinase 1 (RIPK1), a known regulator of cell survival, apoptosis, and necroptosis. In line with this, we showed that RIPK1 was overexpressed in the human cyst epithelium of a subset of patients with polycystic liver disease. Collectively, these data reveal a functional interaction between JNK signaling and RIPK1 in age-related progressive cyst development. Thus, they provide a functional linkage between stress adaptation and programmed cell death (PCD) in the maintenance of liver homeostasis during aging.

Polycystic liver disease genes: Practical considerations for genetic testing

The development of a polycystic liver is a characteristic of the monogenic disorders: autosomal dominant polycystic kidney disease (ADPKD), autosomal recessive polycystic kidney disease (ARPKD), and autosomal dominant polycystic liver disease (ADPLD). Respectively two and one genes mainly cause ADPKD and ARPKD. In contrast, ADPLD is caused by at least six different genes which combined do not even explain the disease development in over half of the ADPLD population. Genetic testing is mainly performed to confirm the likelihood of developing PKD and if renal therapy is essential. However, pure ADPLD patients are frequently not genetically screened as knowledge about the genotype-phenotype correlation is currently limited. This paper will clarify the essence of genetic testing in ADPLD patients.

Deletion of Sox9 in the liver leads to hepatic cystogenesis in mice by transcriptionally downregulating Sec63

Hepatic cysts are found in heterogeneous disorders with different pathogeneses, of which simple hepatic cysts and polycystic liver diseases are two major types. The process of hepatic cytogenesis for these two diseases is caused by defects in remodelling of the ductal plate during biliary tract development, which is called ductal plate malformation. SOX9 is a transcription factor participating in the process of bile duct development, and thus, its dysregulation may play important roles in hepatic cystogenesis. SEC63 encodes an endoplasmic reticulum membrane protein that is mutated in human autosomal dominant polycystic liver disease. However, the transcriptional regulation of SEC63 is largely unknown. In the present study, a liver-specific Sox9 knockout (Sox9^LKO ) mouse was generated to investigate the roles and underlying mechanism of SOX9 in hepatic cystogenesis. We found that hepatic cysts began to be observed in Sox9^LKO mice at 6 months of age. The number and size of cysts increased with age in Sox9^LKO mice. In addition, the characteristics of hepatic cytogenesis, including the activation of proliferation, absence of primary cilium, and disorder of polarity in biliary epithelial cells, were detected in the livers of Sox9^LKO mice. RNAi silencing of SOX9 in human intrahepatic biliary epithelial cells (HIBEpic) resulted in increased proliferation and reduced formation of the primary cilium. Moreover, Sec63 was downregulated in primary biliary epithelial cells from Sox9^LKO mice and SEC63 in HIBEpic transfected with siSOX9. Chromatin immunoprecipitation assays and luciferase reporter assays further demonstrated that SOX9 transcriptionally regulated the expression of SEC63 in biliary epithelial cells. Importantly, the overexpression of SEC63 in HIBEpic partially reversed the effects of SOX9 depletion on the formation of primary cilia and cell proliferation. These findings highlight the biological significance of SOX9 in hepatic cytogenesis and elucidate a novel molecular mechanism underlying hepatic cytogenesis. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Activation of NRF2 ameliorates oxidative stress and cystogenesis in autosomal dominant polycystic kidney disease

Oxidative stress is emerging as a crucial contributor to the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD), but the molecular mechanisms underlying the disturbed redox homeostasis in cystic cells remain elusive. Here, we identified the impaired activity of the NRF2 (nuclear factor erythroid 2–related factor 2) antioxidant pathway as a driver of oxidative damage and ADPKD progression. Using a quantitative proteomic approach, together with biochemical analyses, we found that increased degradation of NRF2 protein suppressed the NRF2 antioxidant pathway in ADPKD mouse kidneys. In a cohort of patients with ADPKD, reactive oxygen species (ROS) frequently accumulated, and their production correlated negatively with NRF2 abundance and positively with disease severity. In an orthologous ADPKD mouse model, genetic deletion of Nrf2 further increased ROS generation and promoted cyst growth, whereas pharmacological induction of NRF2 reduced ROS production and slowed cystogenesis and disease progression. Mechanistically, pharmacological induction of NRF2 remodeled enhancer landscapes and activated NRF2-bound enhancer-associated genes in ADPKD cells. The activation domain of NRF2 formed phase-separated condensates with MEDIATOR complex subunit MED16 in vitro, and optimal Mediator recruitment to genomic loci depended on NRF2 in vivo. Together, these findings indicate that NRF2 remodels enhancer landscapes and activates its target genes through a phase separation mechanism and that activation of NRF2 represents a promising strategy for restoring redox homeostasis and combatting ADPKD.

The role of PPARα in autosomal dominant polycystic kidney disease

PURPOSE OF REVIEW

Metabolic reprogramming is a prominent feature of cyst epithelial cells in autosomal dominant polycystic kidney disease (ADPKD). Peroxisome proliferator activated receptor alpha (PPARα) is a transcription factor that regulates many aspects of cellular metabolism. The purpose of this review is to understand the role of PPARα in ADPKD.

RECENT FINDINGS

PPARα expression is reduced in ADPKD kidneys of mice and humans. This downregulation is in part secondary to microRNA mediated translational repression and leads to impairment of fatty acid metabolism. Genetic studies demonstrate that deletion of Pparα aggravates cyst growth in a slowly progressive mouse model of ADPKD. Recent studies also show that administration of Pparα agonists ameliorates cyst burden in mice.

SUMMARY

Abnormal reduction of PPARα affects cellular metabolism in ADPKD. Pparα is a modulator of cyst progression in mouse models of ADPKD. These studies establish PPARα as an exciting new drug target for the treatment of individuals with ADPKD.

Polycystic liver disease: Classification, diagnosis, treatment process, and clinical management

Polycystic liver disease (PLD) is a rare hereditary disease that independently exists in isolated PLD, or as an accompanying symptom of autosomal dominant polycystic kidney disease and autosomal recessive polycystic kidney disease with complicated mechanisms. PLD currently lacks a unified diagnostic standard. The diagnosis of PLD is usually made when the number of hepatic cysts is more than 20. Gigot classification and Schnelldorfer classification are now commonly used to define severity in PLD. Most PLD patients have no clinical symptoms, and minority with severe complications need treatments. Somatostatin analogues, mammalian target of rapamycin inhibitor, ursodeoxycholic acid and vasopressin-2 receptor antagonist are the potentially effective medical therapies, while cyst aspiration and sclerosis, transcatheter arterial embolization, fenestration, hepatic resection and liver transplantation are the options of invasion therapies. However, the effectiveness of these therapies except liver transplantation are still uncertain. Furthermore, there is no unified strategy to treat PLD between medical centers at present. In order to better understand recent study progresses on PLD for clinical practice and obtain potential directions for future researches, this review mainly focuses on the recent progress in PLD classification, clinical manifestation, diagnosis and treatment. For information, we also provided medical treatment processes of PLD in our medical center.

Estrogen-Containing Oral Contraceptives Are Associated With Polycystic Liver Disease Severity in Premenopausal Patients

The association between estrogen-containing oral contraceptives and history of pregnancies with disease severity in women with polycystic liver disease (PLD) is unclear. We performed a cross-sectional cohort study to assess this association by selecting female patients with PLD of which imaging was available prior to any liver volume-reducing therapy. Patients received a questionnaire to collect detailed information on estrogen use and pregnancies. Preplanned subgroup analyses were performed on premenopausal and postmenopausal patients. The questionnaire was returned by 287 of 360 selected patients (80%). There was no significant association between estrogen-containing oral contraceptives and height-adjusted total liver volume (hTLV) in the total group (P = 0.06) and postmenopausal subgroup (P = 0.7). By contrast, each year of exposure corresponds with a 1.45% higher hTLV (P = 0.02) in the premenopausal subgroup, equivalent to a 15.5% higher hTLV for every 10 years of use. Pregnancy duration was not associated with hTLV. In conclusion, patients with PLD should avoid exogenous estrogens.

Pathobiology of inherited biliary diseases: a roadmap to understand acquired liver diseases

Bile duct epithelial cells, also known as cholangiocytes, regulate the composition of bile and its flow. Acquired, congenital and genetic dysfunctions in these cells give rise to a set of diverse and complex diseases, often of unknown aetiology, called cholangiopathies. New knowledge has been steadily acquired about genetic and congenital cholangiopathies, and this has led to a better understanding of the mechanisms of acquired cholangiopathies. This Review focuses on findings from studies on Alagille syndrome, polycystic liver diseases, fibropolycystic liver diseases (Caroli disease and congenital hepatic fibrosis) and cystic fibrosis-related liver disease. In particular, knowledge on the role of Notch signalling in biliary repair and tubulogenesis has been advanced by work on Alagille syndrome, and investigations in polycystic liver diseases have highlighted the role of primary cilia in biliary pathophysiology and the concept of biliary angiogenic signalling and its role in cyst growth and biliary repair. In fibropolycystic liver disease, research has shown that loss of fibrocystin generates a signalling cascade that increases β-catenin signalling, activates the NOD-, LRR- and pyrin domain-containing 3 inflammasome, and promotes production of IL-1β and other chemokines that attract macrophages and orchestrate the process of pericystic and portal fibrosis, which are the main mechanisms of progression in cholangiopathies. In cystic fibrosis-related liver disease, lack of cystic fibrosis transmembrane conductance regulator increases the sensitivity of epithelial Toll-like receptor 4 that sustains the secretion of nuclear factor-κB-dependent cytokines and peribiliary inflammation in response to gut-derived products, providing a model for primary sclerosing cholangitis. These signalling mechanisms may be targeted therapeutically and they offer a possibility for the development of novel treatments for acquired cholangiopathies.