Bile Ductular Cells Research Articles

Increased p16INK4a-expressing senescent bile ductular cells are associated with inadequate response to ursodeoxycholic acid in primary biliary cholangitis

Background & aimsSenescent biliary epithelial cells (BECs) may be involved in the pathophysiology of primary biliary cholangitis (PBC) by secreting senescence-associated secretory phenotypes. We examined an association of the extent of cellular senescence in BECs with clinicopathological features including response to ursodeoxycholic acid (UDCA) and a possibility of senolytic therapy in PBC. MethodsThe expression of senescent markers (p21WAF1/Cip1, p16INK4a) and B-cell lymphoma–extra large (Bcl-xL), a key regulator of senescent cell anti-apoptotic pathway, was immunohistochemically examined in livers from patients with PBC (n = 145) and 103 control livers. Senolytic effect of Bcl-xL inhibitors (A-1331852 and Navitoclax) was examined in senescent murine BECs. ResultsSenescent BECs were increased in small bile ducts in PBC, compared with control livers (p < 0.01). Senescent BECs were increased in ductular reactions in PBC, stage 3–4, compared with PBC, stage 1–2 and control livers (p < 0.01). The extent of senescent BECs in bile ductules was significantly correlated with stage and hepatitis activity (p < 0.01) and the expression of p16INK4a in bile ductules was significantly correlated to inadequate response to UDCA in PBC (p < 0.01). Double immunofluorescence revealed an increased expression of Bcl-xL in p16INK4a-positive senescent BECs in PBC. Bcl-xL inhibitors selectively induced apoptosis in senescent murine BECs (p < 0.01). ConclusionThe extent of senescent BECs in small bile ducts and bile ductules was closely related to stage and activity of PBC and the increased expression of p16 INK4a in bile ductules was correlated with inadequate response to UDCA.

Knockdown of miR-23, miR-27, and miR-24 Alters Fetal Liver Development and Blocks Fibrosis in Mice.

MicroRNAs (miRNAs) regulate cell fate selection and cellular differentiation. miRNAs of the miR23b polycistron (miR-23b, miR-27b, and miR-24) target components of the TGF-β signaling pathway and affect murine bile ductular and hepatocyte cell fate selection in vitro. Here we show that miR-23b polycistron miRNAs directly target murine Smad4, which is required for TGF-β signaling. Injection of antagomirs against these miRNAs directly into E16.5 murine fetuses caused increased cytokeratin expression in sinusoids and primitive ductular elements throughout the parenchyma of newborn mice. Similar antagomir injection in newborn mice increased bile ductular differentiation in the liver periphery and reduced hepatocyte proliferation. Antagomir injection in newborn Alb/TGF-β1 transgenic mice that develop fibrosis inhibited the development of fibrosis, and injection of older mice caused the resolution of existing fibrosis. Furthermore, murine stellate cell activation, including ColA1 and ACTA2 expression, is regulated by miR-23b cluster miRNAs. In summary, knockdown of miR-23b cluster miRNAs in fetal and newborn liver promotes bile duct differentiation and can block or revert TGF-β-induced liver fibrosis that is dependent on stellate cell activation. These data may find practical application in the highly needed development of therapies for the treatment of fibrosis.

RBMY, a novel inhibitor of glycogen synthase kinase 3β, increases tumor stemness and predicts poor prognosis of hepatocellular carcinoma.

Male predominance of hepatocellular carcinoma (HCC) occurs particularly among young children aged 6-9 years, indicative of a possible role of the Y chromosome-encoded oncogene in addition to an androgenic effect. The discovery of oncogenic activation of RBMY (RNA-binding motif on Y chromosome), which is absent in normal hepatocytes but present in male HCC tissues, sheds light on this issue. Herein, we report on a critical hepatocarcinogenic role of RBMY and its ontogenic origin. During liver development, the Ser/Thr phosphorylated RBMY is expressed in the cytoplasm of human and rodent fetal livers. It is then silenced in mature hepatocytes and restricted to scarce expression in the bile ductular cells. Upon hepatocarcinogenesis, a noteworthy increase of cytoplasmic and nuclear RBMY is observed in HCC tissues; however, only the former is expressed dominantly in hepatic cancer stem cells and correlates significantly to a poor prognosis and decreased survival rate in HCC patients. Cytoplasmic expression of RBMY, which is mediated by binding to nuclear exporter chromosome region maintenance 1 and further enriched upon Wnt-3a stimulation, confers upon tumor cells the traits of cancer stem cell by augmenting self-renewal, chemoresistance, cell-cycle progression, proliferation, and xenograft tumor growth. This is achieved mechanistically through increasing Ser9 phosphorylation-inactivation of glycogen synthase kinase 3β by RBMY, thereby impeding the glycogen synthase kinase 3β-dependent degradation of β-catenin and eventually inducing the nuclear entry of β-catenin for the transcription of downstream oncogenes. RBMY is a novel oncofetal protein that plays a key role in attenuating glycogen synthase kinase 3β activity, leading to aberrant activation of Wnt/β-catenin signaling, which facilitates malignant hepatic stemness; because of its absence from normal human tissues except the testis, RBMY represents a feasible therapeutic target for the selective eradication of HCC cells in male patients.

CRISPLD2 in Hepatic Fibrogenesis and Cholangiocellular Carcinoma Progression

Studies in the past have shown that bile ductular hyperplasia correlates with the degree of hepatic fibrosis and that myofibroblasts are a major component of cholangiocellular carcinoma (CCA). However, the mechanism of cross‐talk between bile ductular epithelial cells and hepatic stellate cells during hepatic fibrogenesis and CCA progression was not established. In this study, we identified CRISPLD2, a secretory protein reported to be critical for epithelial morphogenesis during lung and kidney development, as one of the top differentially up‐regulated genes in the liver of a mouse model of nonalcoholic steatohepatitis (NASH). A combined in situ hybridization, histochemistry, immunohistochemistry and image analysis suggested that CRISPLD2 mRNA was expressed in hepatic stellate cells accompanying bile ductules and collagen fibers in the liver of mouse model of NASH and human cirrhotic liver. Furthermore, cancer‐associated myofibroblasts express CRISPLD2 mRNA in human cholangiocarcinoma tissues. These data suggest that CRISPLD2 may play a role in the branching morphogenesis of biliary epithelial cells and participate in hepatic fibrogenesis and cholangiocellular carcinoma progression. Further characterization of the role of CRISPLD2 is important as it may serve a novel candidate for targeted therapy and/or biomarker for hepatic fibrosis and CCA.

Contributions of Hepatocytes and Bile Ductular Cells in Ductular Reactions and Remodeling of the Biliary System after Chronic Liver Injury

Mature hepatocytes are suggested to possess a capacity for bile ductular transdifferentiation, but whether and how hepatocytes contribute to ductular reaction in chronic liver diseases has not been elucidated. We examined whether mouse hepatocytes can transdifferentiate into bile ductular cells invitro, using a three-dimensional collagen gel culture method, and invivo, using a liver repopulation model in which β-galactosidase-positive hepatocytes from Alb-Cre×ROSA26R mice were transplanted into the liver of wild-type mice. We further examined the relative contribution of intrinsic hepatocytes in ductular reaction in a hepatocyte lineage-tracing model using Mx1-Cre×ROSA26R mice treated with polyinosinic-polycytidylic acid. Within collagen gels, hepatocytes exhibited branching morphogenesis associated with the emergence of bile duct-like phenotype. In the liver repopulation model, many β-galactosidase-positive, hepatocyte-derived bile ductular structures were identified; these markedly increased after liver injury. In Mx1-Cre×ROSA26R mice, relatively minor but significant contributions of hepatocyte-derived bile ductules were observed in both periportal and centrilobular ductular reaction. As the centrilobular ductular reaction progressed, the portal ducts or ductules migrated toward the injured area and joined with hepatocyte-derived ductules, leaving the portal tract without biliary structures. We conclude that hepatocytes and bile ducts or ductules are important sources of ductular reaction and that the intrahepatic biliary system undergoes remarkable remodeling in response to chronic liver injury.

Immunostaining for Polycomb Group Protein EZH2 and Senescent Marker p16INK4a May Be Useful to Differentiate Cholangiolocellular Carcinoma From Ductular Reaction and Bile Duct Adenoma

Intrahepatic cholangiocarcinoma arising in chronic advanced liver disease sometimes contains a component of cholangiolocellular carcinoma. Bile duct adenoma, a benign tumor/tumorous lesion and ductular reaction, is also composed of bile ductular cells, and the differential diagnosis is sometimes difficult. We have previously reported that cholangiolocellular carcinoma showed overexpression of a polycomb group protein EZH2, which participates in bypass/escape from cellular senescence during carcinogenesis. In contrast, the ductular reaction showed high expression of senescence-associated p16(INK4a). In this study, we examined whether immunostaining for EZH2 and p16(INK4a) is useful for differential diagnosis among cholangiolocellular carcinoma, bile duct adenoma, and ductular reactions. Subjects included 33 patients with intrahepatic cholangiocarcinoma and combined hepatocellular-cholangiocarcinoma with components of cholangiolocellular carcinoma and 16 patients with bile duct adenoma. The expressions of EZH2 and p16(INK4a) were examined immunohistochemically. The expression of EZH2 was seen in all cases of cholangiolocellular carcinomas, but it was not observed in bile duct adenomas and ductular reactions, which were seen around carcinomas in 80% of cases. The extensive expression of p16(INK4a) was seen only in 4 cases of cholangiolocellular carcinomas (12%). In contrast, the expression of p16(INK4a) was seen in 13 cases (81%) of bile duct adenomas and in all cases of ductular reactions. The borderline between the component of cholangiolocellular carcinoma and the surrounding ductular reaction was clearly highlighted by the reverse expression pattern of EZH2 and p16(INK4a) in 69% of cases. In conclusion, immunostaining for EZH2 and p16(INK4a) may be useful for differential diagnosis among cholangiolocellular carcinomas, bile duct adenomas, and ductular reactions.

Tumor necrosis factor‐α promotes bile ductular transdifferentiation of mature rat hepatocytes in vitro

We previously showed that mature hepatocytes could transdifferentiate into bile ductular cells when placed in a collagen-rich microenvironment. To explore the mechanism of transdifferentiation, we examined whether inflammatory cytokines affected the phenotype of hepatocytes in a three-dimensional culture system. Spheroidal aggregates of rat hepatocytes were embedded within a type I collagen gel matrix and cultured in the presence of various cytokines. In the control, hepatocytes gradually lost expression of albumin, tyrosine aminotransferase, and hepatocyte nuclear factor (HNF)-4α, while aberrantly expressed bile ductular markers, including cytokeratin 19 (CK 19) and spermatogenic immunoglobulin superfamily (SgIGSF). Among the cytokines examined, tumor necrosis factor (TNF)-α inhibited expression of albumin and HNF-4α, both at mRNA and protein levels. After culturing for 2 weeks with TNF-α, hepatocytic spheroids were transformed into extensively branching tubular structures composed of CK 19- and SgIGSF-positive small cuboidal cells. These cells responded to secretin with an increase in secretion and expressed functional bile duct markers. TNF-α also induced the phosphorylation of Jun N-terminal kinase (JNK) and c-Jun, and the morphogenesis was inhibited by SP600125, a specific JNK inhibitor. Furthermore, in chronic rat liver injury induced by CCl(4) , ductular reaction in the centrilobular area demonstrated strong nuclear staining of phosphorylated c-Jun. Our results demonstrate that TNF-α promotes the ductular transdifferentiation of hepatocytes and suggest a role of TNF-α in the pathogenesis of ductular reaction.

Leucine‐rich repeat‐containing G protein‐coupled receptor 5 expression in ductular reactions after chemotherapy for metastatic colorectal cancer

Oval cells with ductular reactions (DR) in damaged liver are referred to as "intermediate hepatobiliary cells". In a preliminary study, we had found expression of the leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) known as a potential marker for stem cells in the small intestine and colon in DR in liver damaged by chemotherapy for metastatic colorectal cancer (CRC). The aim of this study was to confirm LGR expression in DR in damaged liver after chemotherapy. A total of 68 liver specimens obtained after surgical resection were stained with monoclonal antibodies for cytokeratin (CK)7, neural cell adhesion molecule (NCAM; a bile ductular and liver progenitor cell marker), CD133 (a candidate stem cell marker of hepatocellular carcinoma as well as CRC) and LGR5. Additionally, these mRNA levels were investigated according to the location in damaged liver after chemotherapy using microdissected specimens. We observed that LGR5 was expressed in DR with CD133, CK7 and NCAM expression. By contrast, LGR5, CD133 and NCAM were not expressed in mature bile ducts with CK7. In transcriptional analysis, LGR5 mRNA levels in fibrotic tissue including DR were higher compared with that in adjacent normal liver without significant difference. These findings suggest that LGR5 may be involved in maintaining DR in damaged liver.

Recovery of Mature Hepatocytic Phenotype following Bile Ductular Transdifferentiation of Rat Hepatocytes in Vitro

We previously demonstrated that mature rat hepatocytes transdifferentiate to bile ductular cells when cultured in a three-dimensional collagen-rich matrix. Here, we show that the phenotype of transdifferentiated hepatocytes can be reversed by modulating culture conditions. Spheroidal aggregates of hepatocytes were cultured within a collagen gel matrix in the presence of serum and tumor necrosis factor-α. Spheroids transformed into ductular structures composed of small cuboidal cells, lost the expression of hepatocytic markers, whereas aberrantly expressed bile ductular markers. The transdifferentiated cells were then retrieved from the gels, plated on surfaces coated with a basement membrane-like material, and cultured in serum-free media. Cells spontaneously formed spheroidal aggregates and recovered hepatocytic phenotype. Dexamethasone (Dex), which suppressed the phosphorylation of ERK and Jun N-terminal kinase, facilitated the recovery, and the combination with interleukin-6 or oncostatin M resulted in the recovery of hepatocyte nuclear factor 4 α protein expression and the typical hepatocytic morphology, and a decrease in the expression of bile ductular markers. A cDNA microarray analysis revealed that the hepatocyte-specific mRNA expression profile was recovered in these cells. Our results demonstrate that hepatocytes are able to recover their phenotypes following bile ductular transdifferentiation, suggesting that hepatocytic and bile ductular phenotypes may be mutually reversible.

Abstract 2422: Early features of EMT in Abcb4−/ −-cholangiocytes: A novel cellular model for testing antimetastatic drugs

Abstract Discovering novel drugs for epithelial tumors remains a challenge since cellular events underlying the onset of carcinoma progression are largely unknown. We previously reported the therapeutic effects of oral 5′-methylthioadenosine in the Abcb4−/− mouse (Latasa et al, PLoS ONE 2010: e15690), a clinically relevant model of chronic liver disease leading to carcinoma development. Aiming to gain insight into malignant cellular traits, we then generated primary cultures of intrahepatic bile duct cells from this Abcb4−/− mouse model. We found that Abcb4−/−-cholangiocytes exhibit a fibroblastoid-like appearance which is accompanied by diminished expression of epithelial hallmarks (CK19), and a concomitant up-regulation of mesenchymal markers such as Snail1. The trans-epithelial-electrical-resistance analyses indicated that whereas confluent monolayers of normal cholangiocytes retained the epithelial polarity, Abcb4−/−-cholangiocytes fail to repolarize. Abcb4−/−-cholangiocytes proliferated at reduced growth rates (p&amp;lt;0.05), formed a higher number of colonies in soft agar (p&amp;lt;0.01) and were less sensitive to antiproliferative effect of TGFβ1 (p&amp;lt;0.05). Consistent with EMT characteristics, Abcb4−/−-cholangiocytes induced TGFβ isoforms and were more sensitive to TGFβ1-signaling. Collectively, this data suggests that Abcb4−/− cholangiocytes acquire EMT features that may be largely regulated in vivo by TGFβ1. This original bile ductular cell line of Abcb4−/−-cholangiocytes will be useful for testing compounds that may interfere with metastatic malignancy of EMT. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2422. doi:1538-7445.AM2012-2422

Autophagy May Precede Cellular Senescence of Bile Ductular Cells in Ductular Reaction in Primary Biliary Cirrhosis

Recent studies disclosed that autophagy facilitates the process of senescence. Given that cellular senescence is involved in the pathophysiology of ductular reaction (DR) in primary biliary cirrhosis (PBC), we examined an involvement of autophagy in DRs in PBC and control livers. We examined immunohistochemically the expression of microtubule-associated proteins light chain 3β (LC3) as autophagy marker, p62/sequestosome-1 (p62) as autophagy-related marker in bile ductular cells in livers taken from the patients with PBC (n = 42), and control livers (n = 100). The expression of senescent markers (p16(INK4a) and p21(WAF1/Cip1)) in bile ductular cells and their correlation with autophagy was also evaluated. The expression of LC3 was seen in coarse vesicles in the cytoplasm of bile ductular cells and significantly more frequently in PBC of both early and advanced stages when compared to control livers (p < 0.01). The expression of p62 was seen as intracytoplasmic aggregates and significantly more frequently in PBC when compared to control livers (p < 0.05). The expression of LC3 and p62 significantly correlated with each other (p < 0.01). The expression of LC3 and p62 significantly correlated with the expression of p16(INK4a), p21(WAF1/Cip1) (p < 0.05). Autophagy is frequently seen in bile ductular cells in DRs in PBC. Since cellular senescence of bile ductular cells is rather frequent in the advanced stage of PBC, autophagy may precede cellular senescence of bile ductular cells in DRs in PBC.

Participation of bile ductular cells in the pathological progression of non-alcoholic fatty liver disease

AimsNon-alcoholic fatty liver disease (NAFLD) represents a spectrum of pathological conditions, ranging from simple steatosis to hepatic fibrosis with progression to cirrhosis. While activated hepatic stellate cells (HSC) are known...

Pluripotent plasticity of stem cells and liver repopulation

Different types of stem cells have a role in liver regeneration or fibrous repair during and after several liver diseases. Otherwise, the origin of hepatic and/or extra-hepatic stem cells in reactive liver repopulation is under controversy. The ability of the human body to self-repair and replace the cells and tissues of some organs is often evident. It has been estimated that complete renewal of liver tissue takes place in about a year. Replacement of lost liver tissues is accomplished by proliferation of mature hepatocytes, hepatic oval stem cells differentiation, and sinusoidal cells as support. Hepatic oval cells display a distinct phenotype and have been shown to be a bipotential progenitor of two types of epithelial cells found in the liver, hepatocytes, and bile ductular cells. In gastroenterology and hepatology, the first attempts to translate stem cell basic research into novel therapeutic strategies have been made for the treatment of several disorders, such as inflammatory bowel diseases, diabetes mellitus, celiachy, and acute or chronic hepatopaties. In the future, pluripotent plasticity of stem cells will open a variety of clinical application strategies for the treatment of tissue injuries, degenerated organs. The promise of liver stem cells lie in their potential to provide a continuous and readily available source of liver cells that can be used for gene therapy, cell transplant, bio-artificial liver-assisted devices, drug toxicology testing, and use as an in vitro model to understand the developmental biology of the liver.

Bile ductular cell reaction with senescent hepatocytes in chronic viral hepatitis is lost during hepatocarcinogenesis

Cellular senescence is defined as irreversible cell arrest and could work as a safeguard against tumorigenesis. This mechanism was examined in chronic viral hepatitis-related hepatocarcinogenesis. By using surgical resected or wedge biopsied liver specimens from 87 chronic viral hepatitis patients in whom 35 neoplastic nodules (dysplastic nodules and hepatocellular carcinoma) were complicated, P21 expression and senescence-associated beta galactosidase activity, a marker of senescence, were examined. All of these neoplastic nodules harbored portal tracts within the tumors. Hepatocytes expressing senescence markers and cytokeratin (CK)7-positive bile ductules including hepatic progenitor-like cells were increased in periseptal areas in cirrhosis. Interestingly, these cells appeared to form an anatomical complex that was completely lost in the periportal areas within the neoplastic nodules. In one-third of the neoplastic nodules, CK7-positive small neoplastic hepatocytes resembling hepatic progenitor cells proliferated zonally around the portal tracts. In conclusion, loss of a complex of senescent hepatocytes and ductular cell including hepatic progenitor-like cells in the periportal or periseptal areas may be associated with emergence of neoplastic hepatocytes and their proliferation followed by neoplastic nodules arising in liver cirrhosis. Zonal proliferation of CK7-positive small neoplastic hepatocytes resembling hepatic progenitor cells may develop during early hepatocarcinogenesis.

Adenovirus-Mediated CTLA4Ig Gene Transfer Improves the Survival of Grafted Human Hepatic Progenitors in Mouse Liver

The invasive nature of surgery and limited numbers of donor livers for end-stage patients has prompted the search for alternative cell therapies for intractable hepatic disease. Hepatocyte ransplantations have been performed for a variety of indications, but sustained benefits have not been observed in most cases. Rat fetal liver epithelial cells (liver stem cells) have demonstrated self-renewal in vivo and functional repopulation of the liver. We have previously isolated and expanded epithelial progenitor cells (EPC) from the human fetal liver to investigate their differentiation potential. In this study, we applied suppression of immunorejection by adenoviral CTLA4Ig gene delivery mediated to examine the survival and differentiation of human fetal EPC transplanted into normal mouse liver. The grafted EPC showed extensive proliferation at both 1 and 2 months after transplantation compared with controls. Moreover, most EPC differentiated into hepatocytes, while a small fraction became bile ductular cells. This finding suggested that human fetal EPC may be a ideal source of cell-based therapy for various liver diseases.

Hedgehog signaling regulates epithelial-mesenchymal transition during biliary fibrosis in rodents and humans

Epithelial-mesenchymal transitions (EMTs) play an important role in tissue construction during embryogenesis, and evidence suggests that this process may also help to remodel some adult tissues after injury. Activation of the hedgehog (Hh) signaling pathway regulates EMT during development. This pathway is also induced by chronic biliary injury, a condition in which EMT has been suggested to have a role. We evaluated the hypothesis that Hh signaling promotes EMT in adult bile ductular cells (cholangiocytes). In liver sections from patients with chronic biliary injury and in primary cholangiocytes isolated from rats that had undergone bile duct ligation (BDL), an experimental model of biliary fibrosis, EMT was localized to cholangiocytes with Hh pathway activity. Relief of ductal obstruction in BDL rats reduced Hh pathway activity, EMT, and biliary fibrosis. In mouse cholangiocytes, coculture with myofibroblastic hepatic stellate cells, a source of soluble Hh ligands, promoted EMT and cell migration. Addition of Hh-neutralizing antibodies to cocultures blocked these effects. Finally, we found that EMT responses to BDL were enhanced in patched-deficient mice, which display excessive activation of the Hh pathway. Together, these data suggest that activation of Hh signaling promotes EMT and contributes to the evolution of biliary fibrosis during chronic cholestasis.

Role of hedgehog signalling in bile ductular cells

Acute and chronic liver pathologies represent an important source of morbidity and mortality. Understanding the mechanisms of cell survival, repair and proliferation are critical to the development of future therapies...

Hedgehog-mediated mesenchymal–epithelial interactions modulate hepatic response to bile duct ligation

In bile duct-ligated (BDL) rodents, as in humans with chronic cholangiopathies, biliary obstruction triggers proliferation of bile ductular cells that are surrounded by fibrosis produced by adjacent myofibroblastic cells in the hepatic mesenchyme. The proximity of the myofibroblasts and cholangiocytes suggests that mesenchymal–epithelial crosstalk promotes the fibroproliferative response to cholestatic liver injury. Studying BDL mice, we found that bile duct obstruction induces activity of the Hedgehog (Hh) pathway, a system that regulates the viability and differentiation of various progenitors during embryogenesis. After BDL, many bile ductular cells and fibroblastic-appearing cells in the portal stroma express Hh ligands, receptor and/or target genes. Transwell cocultures of an immature cholangiocyte line that expresses the Hh receptor, Patched (Ptc), with liver myofibroblastic cells demonstrated that both cell types produced Hh ligands that enhanced each other's viability and proliferation. Further support for the concept that Hh signaling modulates the response to BDL was generated by studying PtcLacZ mice, which have an impaired ability to constrain Hh signaling due to a heterozygous deficiency of Ptc. After BDL, PtcLacZ mice upregulated fibrosis gene expression earlier than wild-type controls and manifested an unusually intense ductular reaction, more expanded fibrotic portal areas, and a greater number of lobular necrotic foci. Our findings reveal that adult livers resurrect developmental signaling systems, such as the Hh pathway, to guide remodeling of the biliary epithelia and stroma after cholestatic injury.

IL‐8 expression by biliary epithelial cells is associated with neutrophilic infiltration and reactive bile ductules

Reactive bile ductule is a non-specific feature of various hepatobiliary diseases, and is not infrequently accompanied by neutrophilic infiltration. Recently, biliary epithelial cells have been shown to secrete cytokines and chemokines and to express components of the mucosal immune system such as Toll-like receptors. We examined the expression of a neutrophil chemo-attractant, interluekin (IL)-8, in bile ductular cells to clarify the histogenesis of reactive bile ductules with neutrophilic infiltration using human liver tissues (eight cases of chronic viral hepatitis, seven cases of liver cirrhosis (LC), seven cases of sepsis, 11 cases of extrahepatic biliary obstruction (EBO), three cases of fulminant hepatitis (FH), five cases of primary biliary cirrhosis, and three cases of primary sclerosing cholangitis). Human neutrophil peptides 1-3 (HNP1-3) were used as markers of neutrophils. Immunohistochemically, IL-8 was detected in bile ductules in various diseased livers. HNP1-3-positive neutrophils were significantly dense around IL-8-positive bile ductules compared with IL-8-negative ductules in septic liver, LC, EBO, and FH. Experiments in vitro showed that cultured human biliary epithelial cells expressed and secreted IL-8 in response to lipopolysaccharide and also IL-1beta and tumour necrosis factor-alpha. Neutrophilic infiltration around reactive bile ductules may be related to the IL-8 expressed in bile ductular epithelia, possibly induced by bacterial components and proinflammatory cytokines released locally.

Identification of hepatocytic and bile ductular cell lineages and candidate stem cells in bipolar ductular reactions in cirrhotic human liver

Hepatocyte function and regeneration are severely compromised in severe liver disease, and a common sequela is cirrhosis. Structural changes caused by cirrhosis create a cellular environment conducive to the formation of ductular reactions (DRs). Ductular reactions are primarily composed of oval cells also known as "intermediate hepatobiliary cells". We have conducted single, double, and triple staining to study lineages of oval cells present in DRs. Staining with NCAM, CK19, and HepPar1 has revealed a distinctly bipolar structure to DRs that are embedded in cirrhotic tissue. Spatial analysis of cells that are singly HepPar1-positive, or CK19-positive, has revealed hepatocytic and biliary poles, respectively, in the DRs. Also, the location of singly NCAM-positive cells in DRs suggests that they may be bipotent liver stem/progenitor cells. The locations of other intermediate hepatobiliary cells, which have combinations of markers, suggest that CK19+/NCAM+ cells are transitional cells in the biliary lineage and that rare cells that are negative for all three markers are transitional cells in the hepatocytic lineage. A working cell lineage model for DRs is presented.