Cholangiocyte pathobiology.

Cholangiocytes, the epithelial cells lining the intrahepatic and extrahepatic bile ducts, are highly specialized cells residing in a complex anatomic niche where they participate in bile production and homeostasis. Cholangiocytes are damaged in a variety of human diseases termed cholangiopathies, often causing advanced liver failure. The regulation of cholangiocyte transport properties is increasingly understood, as is their anatomical and functional heterogeneity along the biliary tract. Furthermore, cholangiocytes are pivotal in liver regeneration, especially when hepatocyte regeneration is compromised. The role of cholangiocytes in innate and adaptive immune responses, a critical subject relevant to immune-mediated cholangiopathies, is also emerging. Finally, reactive ductular cells are present in many cholestatic and other liver diseases. In chronic disease states, this repair response contributes to liver inflammation, fibrosis and carcinogenesis and is a subject of intense investigation. This Review highlights advances in cholangiocyte research, especially their role in development and liver regeneration, their functional and biochemical heterogeneity, their activation and involvement in inflammation and fibrosis and their engagement with the immune system. We aim to focus further attention on cholangiocyte pathobiology and the search for new disease-modifying therapies targeting the cholangiopathies.

[Immune-mediated cholangiopathies : Diagnostic and therapeutic challenges]. / Autoimmunassoziierte Gallenwegserkrankungen : Diagnostische und therapeutische Herausforderungen.

BACKGROUND: Immune-mediated cholangiopathies comprise primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and IgG4-associated cholangitis (IAC). A common feature is the progressive destruction of bile ducts leading to cholestasis with fibrosis and cirrhosis of the liver over time. The diseases are mostly identified during routine laboratory testing. Clinical signs and symptoms such as pruritus, fatigue or jaundice are infrequent in the early stage. DIAGNOSIS: The diagnostic work-up involves the patient's history, physical examination, serological tests, abdominal ultrasonography, magnetic resonance cholangiopancreatography (MRCP) and, where necessary, liver biopsy and genetic testing. THERAPY: Ursodeoxycholic acid (UDCA) is an effective treatment of PBC. Second-line therapies in addition to UDCA for incomplete UDCA responders are obeticholic acid (OCA) and bezafibrate, whereby only OCA has received approval for this indication from American (Federal Drug Administration) and European (European Medicines Agency) authorities. In PSC, UDCA improves prognostic markers; dominant bile duct strictures are treated with endoscopic balloon dilatation. Despite therapy, liver transplantation is frequently necessary for PSC. The risk of developing cholangiocarcinoma, colon cancer, and gallbladder cancer is increased for patients with PSC. In contrast to PBC and PSC, IAC responds well to corticosteroids. Disease relapse, however, is common, making long-term treatment with low-dose prednisolone or azathioprine necessary.

Inflammation and the Gut-Liver Axis in the Pathophysiology of Cholangiopathies.

Cholangiocytes, the epithelial cells lining the bile ducts, represent the unique target of a group of progressive diseases known as cholangiopathies whose pathogenesis remain largely unknown. In normal conditions, cholangiocytes are quiescent and participate to the final bile volume and composition. Following exogenous or endogenous stimuli, cholangiocytes undergo extensive modifications of their phenotype. Reactive cholangiocytes actively proliferate and release a set of proinflammatory molecules, which act in autocrine/paracrine manner mediating the cross-talk with other liver cell types and innate and adaptive immune cells. Cholangiocytes themselves activate innate immune responses against gut-derived microorganisms or bacterial products that reach the liver via enterohepatic circulation. Gut microbiota has been implicated in the development and progression of the two most common cholangiopathies, i.e., primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC), which have distinctive microbiota composition compared to healthy individuals. The impairment of intestinal barrier functions or gut dysbiosis expose cholangiocytes to an increasing amount of microorganisms and may exacerbate inflammatory responses thus leading to fibrotic remodeling of the organ. The present review focuses on the complex interactions between the activation of innate immune responses in reactive cholangiocytes, dysbiosis, and gut permeability to bacterial products in the pathogenesis of PSC and PBC.

Relapse rate and predictors of relapse in a large single center cohort of type 1 autoimmune pancreatitis: long-term follow-up results after steroid therapy with short-duration maintenance treatment.

BACKGROUND: Type 1 autoimmune pancreatitis (AIP), as a pancreatic manifestation of IgG4-related disease, shows a favorable prognosis in the short term. However, disease relapse is common in long-term follow-up, despite a successful initial treatment response. This study aimed to identify the predictors of relapse and long-term outcomes in patients with type 1 AIP. METHODS: Patients with more than 2 years of follow-up who met the International Consensus Diagnostic Criteria for type 1 AIP were included. Patients who had undergone pancreatic operations associated with AIP or who lacked sufficient clinical data were excluded. RESULTS: All 138 patients achieved clinical remission with initial steroid therapy, and 66 (47.8%) experienced relapse during a median 60 (range 24-197) months follow-up. Among the relapsed patients, about 74% (49/66) relapsed within 3 years. About 60% (82/138) had other organ involvement (OOI), most commonly in the proximal bile duct (26.8%). At first diagnosis, OOI, and especially OOI of the proximal bile duct, was a significant independent predictor of relapse (hazard ratio 2.65; 95% confidence interval 1.44-4.89; p = 0.002), according to multivariate analysis. During the follow-up period, 16 (11.6%) patients experienced endocrine/exocrine dysfunction and 32 (23.2%) patients developed de novo pancreatic calcifications/stones. No pancreatic cancer occurred in any patients. CONCLUSIONS: Type 1 AIP has common relapses, and patients with OOI, especially OOI of the proximal bile duct, appear to be at increased risk for relapse. Long-term sequelae, including pancreatic insufficiency and pancreatic calcifications/stones, are common in patients with relapse. To reduce the relapse, longer maintenance treatment may be needed especially for patients at high risk for relapse.

Gene-disease associations identify a connectome with shared molecular pathways in human cholangiopathies.

Cholangiopathies are a diverse group of progressive diseases whose primary cell targets are cholangiocytes. To identify shared pathogenesis and molecular connectivity among the three main human cholangiopathies (biliary atresia [BA], primary biliary cholangitis [PBC], and primary sclerosing cholangitis [PSC]), we built a comprehensive platform of published data on gene variants, gene expression, and functional studies and applied network-based analytics in the search for shared molecular circuits. Mining the data platform with largest connected component and interactome analyses, we validated previously reported associations and identified essential and hub genes. In addition to disease-specific modules, we found a substantial overlap of disease neighborhoods and uncovered a group of 34 core genes that are enriched for immune processes and abnormal intestine/hepatobiliary mouse phenotypes. Within this core, we identified a gene subcore containing signal transduction and activator of transcription 3, interleukin-6, tumor necrosis factor, and forkhead box P3 prominently placed in a regulatory connectome of genes related to cellular immunity and fibrosis. We also found substantial gene enrichment in the advanced glycation endproduct/receptor for advanced glycation endproducts (RAGE) pathway and showed that RAGE activation induced cholangiocyte proliferation. Conclusion: Human cholangiopathies share pathways enriched by immunity genes and a molecular connectome that links different pathogenic features of BA, PBC, and PSC. (Hepatology 2018;67:676-689).

The role of macrophages in the development of biliary injury in a lipopolysaccharide-aggravated hepatic ischaemia-reperfusion model.

INTRODUCTION: Endotoxins, in the form of lipopolysaccharides (LPS), are potent inducers of biliary injury. However the mechanism by which injury develops remains unclear. We hypothesized that hepatic macrophages are pivotal in the development of endotoxin-induced biliary injury and that no injury would occur in their absence. MATERIAL AND METHODS: Clodronate liposomes were used to deplete macrophages from the liver. Forty-eight rats were equally divided across six study groups: sham operation (sham), liposome treatment and sham operation (liposomes+sham), 1mg/kg LPS i.p. (LPS), liposome treatment and LPS administration (liposomes+LPS), hepatic ischaemia-reperfusion injury with LPS administration (IRI+LPS) and liposome treatment followed by IRI+LPS (liposomes+IRI+LPS). Following 6h of reperfusion, blood, bile, and liver tissue was collected for further analysis. Small bile duct injury was assessed, serum liver tests were performed and bile composition was evaluated. The permeability of the blood-biliary barrier (BBB) was assessed using intravenously administered horseradish peroxidase (HRP). RESULTS: The presence of hepatic macrophages was reduced by 90% in LPS and IRI+LPS groups pre-treated with clodronate liposomes (P<0.001). Severe small bile duct injury was not affected by macrophage depletion, and persisted in the liposomes+IRI+LPS group (50% of animals) and liposomes+LPS group (75% of animals). Likewise, BBB impairment persisted following macrophage depletion. LPS-induced elevation of the chemokine Mcp-1 in bile was not affected by macrophage depletion. CONCLUSIONS: Depletion of hepatic macrophages did not prevent development of biliary injury following LPS or LPS-enhanced IRI. Cholangiocyte activation rather than macrophage activation may underlie this injury. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Attenuation of alpha-naphthylisothiocyanate (ANIT)-induced biliary fibrosis by depletion of hepatic macrophages in rats.

Biliary fibrosis is a complex process in which macrophages and myofibroblasts may play central roles. We investigated biliary fibrosis lesions induced in the Glisson's sheath in rats by alpha-naphthylisothiocyanate (ANIT) administration under macrophage depletion. Hepatic macrophages were depleted in F344 rats with liposome-encapsulated clodronate (CLD) (10mL/kg body weight, i.v) followed by bile duct injury with ANIT (75mg/kg body weight, i.p) (ANIT+CLD group). Rats received empty-liposomes (Lipo) followed by ANIT, and served as control (ANIT+Lipo group). In both ANIT+Lipo and ANIT+CLD groups, ANIT-induced bile duct injury with inflammatory cell infiltration was seen on days 1-3, and subsequently reparative fibrosis occurred on days 5 and 7. In comparisons between the two groups, macrophages reacting to CD68, CD163, MHC class II and CD204 were less in numbers in ANIT+CLD group; the most sensitive immunophenotype was of CD163-positive. Furthermore, in ANIT+CLD group interstitial mesenchymal cells/myofibroblasts reacting to vimentin, desmin and α-smooth muscle actin were also less in grades and tended to be delayed in appearance. Interestingly, MCP-1, IFN-γ, IL-10, and TGF-ß1 mRNAs were significantly increased mainly on day 2 in ANIT+Lipo group, while the levels of these factors were prominently lower in ANIT+CLD group. Collectively, depletion of hepatic macrophages plays roles in attenuating biliary fibrogenesis by production of inflammatory factors. The present results indicated clearly importance of macrophage functions in the pathogenesis of biliary fibrosis.

The role of natural killer T cells in a mouse model with spontaneous bile duct inflammation.

Natural killer T (NKT) cells are activated by lipid antigens presented by CD1d molecules and represent a major lymphocyte subset of the liver. NODc3c4 mice spontaneously develop biliary inflammation in extra- and intrahepatic bile ducts. We demonstrated by flow cytometry that invariant NKT (iNKT) cells were more abundant in the thymus, spleen, and liver of NODc3c4 mice compared to NOD mice. iNKT cells in NODc3c4 mice displayed an activated phenotype. Further, NOD and NODCd1d-/- mice were irradiated and injected with NODc3c4 bone marrow, and injection of NODc3c4 bone marrow resulted in biliary infiltrates independently of CD1d expression in recipient mice. Activation or blocking of NKT cells with α-galactosylceramide or anti-CD1d antibody injections did not affect the biliary phenotype of NODc3c4 mice. NODc3c4.Cd1d-/- mice were generated by crossing NODCd1d-/- mice onto a NODc3c4 background. NODc3c4.Cd1d-/- and NODc3c4 mice developed the same extent of biliary disease. This study demonstrates that iNKT cells are more abundant and activated in the NODc3c4 model. The portal inflammation of NODc3c4 mice can be transferred to irradiated recipients, which suggests an immune-driven disease. Our findings imply that NKT cells can potentially participate in the biliary inflammation, but are not the primary drivers of disease in NODc3c4 mice.

Histopathology of IgG4-Related Autoimmune Hepatitis and IgG4-Related Hepatopathy in IgG4-Related Disease.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic disease involving many organs; it includes IgG4-related sclerosing cholangitis and inflammatory pseudotumor in the hepatobiliary system. Two types of hepatic parenchymal involvement have been reported in IgG4-RD: IgG4-related autoimmune hepatitis (AIH) and IgG4-hepatopathy. Moreover, only three cases of IgG4-related AIH have been reported. Immunoglobulin G4-related AIH is clinicopathologically similar to AIH, except for an elevated serum IgG4 level and heavy infiltration of IgG4-positive plasma cells in the liver tissue. Interestingly, IgG4-related AIH can be complicated by well-known IgG4-RD(s). Immunoglobulin G4-hepatopathy, which includes various histopathological lesions encountered in the liver of patients with type I autoimmune pancreatitis, is classified into five histological categories: portal inflammation, large bile duct damage, portal sclerosis, lobular hepatitis, and cholestasis. Immunoglobulin G4-hepatopathy is currently a collective term covering hepatic lesions primarily or secondarily related to IgG4-related sclerosing cholangitis and type 1 autoimmune pancreatitis. In conclusion, the liver is not immune to IgG4-RD, and at least two types of hepatic involvement in IgG4-RD have been reported: IgG4-related AIH and IgG4-hepatopathy. Additional studies are required to clarify their precise clinical significance with respect to IgG4-RD and inherent liver diseases.

Immunoglobulin G4(+) B-cell receptor clones distinguish immunoglobulin G 4-related disease from primary sclerosing cholangitis and biliary/pancreatic malignancies.

UNLABELLED: Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) of the biliary tree and pancreas is difficult to distinguish from sclerosing cholangitis and biliary/pancreatic malignancies (CA). An accurate noninvasive test for diagnosis and monitoring of disease activity is lacking. We demonstrate that dominant IgG4(+) B-cell receptor (BCR) clones determined by next-generation sequencing accurately distinguish patients with IgG4-associated cholangitis/autoimmune pancreatitis (n = 34) from those with primary sclerosing cholangitis (n = 17) and CA (n = 17). A novel, more affordable, and widely applicable quantitative polymerase chain reaction (qPCR) protocol analyzing the IgG4/IgG RNA ratio in blood also achieves excellent diagnostic accuracy (n = 125). Moreover, this qPCR test performed better than serum IgG4 levels in sensitivity (94% vs. 86%) and specificity (99% vs. 73%) and correlates with treatment response (n = 20). CONCLUSIONS: IgG4(+) BCR clones and IgG4/IgG RNA ratio markedly improve delineation, early diagnosis, and monitoring of IgG4-RD of the biliary tree and pancreas. (Hepatology 2016;64:501-507).

Hepatobiliary IgG4 Cholangiopathy: Case Series and Literature Review.

IgG4 cholangiopathy is a recently described distinctive type of hepatobiliary manifestation of IgG4-related disease. This is often misdiagnosed as a malignancy of the hepatobiliary system on clinical presentation and imaging. Accurate diagnosis is crucial for appropriate management. Histopathology provides crucial information and is characterized by IgG4-positive lymphoplasmacytic infiltration with storiform fibrosis and obliterative phlebitis. We present the clinicopathological spectrum of a retrospective series of 6 cases of IgG4 cholangiopathy that clinically masqueraded as hepatobiliary malignancies.

IgG4-related cholangitis: Case report and literature review.

CASE PRESENTATION: We describe a case of a patient who presents with jaundice, elevated cholestatic liver enzymes, an extreme weight loss and a midcholedochal stricture very suspect for a cholangiocarcinoma. In the conviction of malignancy, although the absence of anatomopathological prove, the patient underwent a choledochal resection. The anatomopathological specimen revealed no malignancy. In the year following resection, the patient keeps presenting with bile duct strictures and further weight loss. Ultimately the diagnosis of Ig G4-related cholangitis is withheld. Therapy with corticosteroids is initiated with a spectacular clinical, biochemical and radiographical result. DISCUSSION: IgG4-related cholangitis is the biliary presentation of IgG4-related disease, a recently discovered entity of fibroinflammatory masses which can affect virtually every organ in the body. It is characterized by a dense lymphoplasmacytic infiltrate, storiform fibrosis, obliterative phlebitis and a presence of > 30 IgG4-positive plasma cells per high power field. Main differential diagnosis contains cholangiocarcinoma and primary sclerosing cholangitis. Corticoids are cornerstone of therapy, with azathioprine frequently used as a maintenance in case of relapse. CONCLUSIONS: With this case we want to draw the attention to a rather uncommon cause of biliary obstruction, easily mistaken for a cholangiocarcinoma.

IgG4 cholangiopathy: current concept, diagnosis, and pathogenesis.

IgG4 related cholangiopathy, a distinctive type of cholangitis of unknown origin, is characterized by increased serum levels of IgG4, massive infiltration of IgG4-positive plasma cells with storiform fibrosis and/or obliterative phlebitis in the thickened bile duct wall, and good response to steroids. Patients with IgG4-cholangiopathy are frequently associated with autoimmune pancreatitis; IgG4-cholangiopathy is recognized as a biliary manifestation of IgG4-related disease. This condition can be diagnosed by a combination of imaging, serology, histopathology, and steroid responsiveness; however, cholangiographic features are often difficult to differentiate from primary sclerosing cholangitis, pancreatic cancer, or cholangiocarcinoma. The Japanese clinical diagnostic criteria for IgG4-related sclerosing cholangitis established in 2012 are useful in the diagnosis of IgG4-cholangiopathy. Although the precise pathogenic mechanism remains unclear, the development of IgG4-cholangiopathy may involve: susceptible genetic factors, abnormal innate and acquired immunity, decreased naïve regulatory T cells, and specific B cell responses. Further studies on genetic backgrounds, disease specific antigens, and the role of IgG4 are necessary to clarify the pathogenesis.

Relapse of IgG4-related sclerosing cholangitis after steroid therapy: image findings and risk factors.

OBJECTIVES: To compare imaging data from IgG4-related sclerosing cholangitis (IgG4-SC) obtained at initial attack and at relapse, and to determine risk factors predicting relapse of IgG4-SC after steroid therapy. METHODS: Twenty-three patients with relapsed IgG4-SC and 36 non-relapsed patients were included. Computed tomography, magnetic resonance cholangiography, and endoscopic retrograde cholangiography were used to determine biliary and extrabiliary involvement. Images taken at the time of the initial attack were compared with those taken at relapse. Risk factors were determined by comparing clinical and imaging factors in the relapse and non-relapse groups. RESULTS: In comparison to the initial attack, relapsed IgG4-SC was characterised by more frequent extrapancreatic and multiple bile duct strictures, increased bile duct segment involvement, thicker bile duct walls, and a less frequent association with autoimmune pancreatitis (AIP) (P ≤ 0.016). Compared with non-relapse, relapse was significantly associated with less frequent use of maintenance steroid therapy, more frequent extrapancreatic and multiple bile duct strictures, increased bile duct segment involvement, and thicker bile duct walls during the initial attack (P ≤ 0.021). CONCLUSIONS: Relapsed IgG4-SC presented with a more aggressive appearance on imaging than the initial attack. The degree of bile duct involvement and use of maintenance steroid therapy were associated with relapse of IgG4-SC.

Isolated hepatobiliary cryptococcosis manifesting as obstructive jaundice in an immunocompetent child: case report and review of the literature.

The majority of patients with symptomatic cryptococcosis have an underlying immunocompromising condition. In the absence of coexisting immunocompromising condition, Cryptococcus neoformans is rarely considered in the differential diagnosis of obstructive jaundice that occurs in children with hilar masslike lesion. Here, we report a 5-year-old boy without immunoglobulin or lymphocyte abnormalities who developed a hepatobiliary infection with C. neoformans. Ultrasonography and computed tomography showed dilatation of the bilateral intrahepatic bile ducts and a low-attenuated mass in the hepatic hilum. Microscopic examination of tissue samples revealed abundant numbers of encapsulated yeast cell suggestive of C. neoformans. After 4 months of antifungal therapy (liposomal amphotericin B for 2 weeks and oral fluconazole for 3 months), the disease was effectively controlled. Unnecessary operation could be avoided by an early and accurate diagnosis. By sharing our experience, we suggest hepatobiliary surgeons and gastroenterologists should have a suspicion of this unusual entity to make earlier diagnosis and treatment.

Innate immunity in the pathogenesis of cholangiopathy: a recent update.

Biliary innate immunity is involved in the pathogenesis of cholangiopathies in patients with various biliary diseases. Biliary epithelial cells possess an innate immune system consisting of the Toll-like receptor (TLR) family and recognize pathogen-associated molecular patterns (PAMPs). Recently, regulatory mechanisms by intracellular negative regulators including peroxisome proliferator-activated receptor-γ and micro-RNA have been clarified. In primary biliary cirrhosis (PBC) and primary sclerosing cholangitis, dysregulated biliary innate immunity, namely hyper-responsiveness to PAMPs, is associated with the histopathogenesis of cholangiopathy. Moreover, biliary epithelial cells produce monocyte chemotactic protein-1 (MCP-1/CCL2) as a result of the innate immune response and bile ductules play a role in hepatic fibrosis caused by hepatic stellate cells (HSCs). Also, biliary innate immune responses induce the production of two chemokines, fractalkine and macrophage inflammatory protein-3α (MIP-3α), causing the migration of inflammatory cells and a population of antigen-presenting cell found in epithelium, Langerhans cell, and involve chronic cholangitis associated with biliary epithelium-specific innate and acquired immunity in PBC.

Elevated plasma IL-6 associates with increased risk of advanced fibrosis and cholangiocarcinoma in individuals infected by Opisthorchis viverrini.

Opisthorchis viverrini is considered among the most important of the food-borne trematodes due to its strong association with advanced periductal fibrosis and bile duct cancer (cholangiocarcinoma). We investigated the relationship between plasma levels of Interleukin (IL)-6 and the risk of developing advanced fibrosis and bile duct cancer from chronic Opisthorchis infection. We show that IL-6 circulates in plasma at concentrations 58 times higher in individuals with advanced fibrosis than age, sex, and nearest-neighbor matched controls and 221 times higher in individuals with bile duct cancer than controls. We also observed a dose-response relationship between increasing levels of plasma IL-6 and increasing risk of advanced fibrosis and bile duct cancer; for example, in age and sex adjusted analyses, individuals with the highest quartiles of plasma IL-6 had a 19 times greater risk of developing advanced periductal fibrosis and a 150 times greater risk of developing of bile duct cancer than individuals with no detectable level of plasma IL-6. Finally, we show that a single plasma IL-6 measurement has excellent positive predictive value for the detection of both advanced bile duct fibrosis and bile duct cancer in regions with high O. viverrini transmission. These data support our hypothesis that common mechanisms drive bile duct fibrosis and bile duct tumorogenesis from chronic O. viverrini infection. Our study also adds a unique aspect to the literature on circulating levels of IL-6 as an immune marker of hepatobiliary pathology by showing that high levels of circulating IL-6 in plasma are not related to infection with O. viverrini, but to the development of the advanced and often lethal pathologies resulting from chronic O. viverrini infection.