Bile Duct Epithelial Cells Research Articles

The Coagulation System Contributes to αVβ6 Integrin Expression and Liver Fibrosis Induced by Cholestasis

Chronic injury to intrahepatic bile duct epithelial cells (BDECs) elicits expression of various mediators, including the αVβ6 integrin, promoting liver fibrosis. We tested the hypothesis that tissue factor (TF)-dependent thrombin generation and protease activated receptor-1 (PAR-1) activation contribute to liver fibrosis induced by cholestasis via induction of αVβ6 expression. To test this hypothesis, mice deficient in either TF or PAR-1 were fed a diet containing 0.025% α-naphthylisothiocyanate (ANIT), a BDEC-selective toxicant. In genetically modified mice with a 50% reduction in liver TF activity fed an ANIT diet, coagulation cascade activation and liver fibrosis were reduced. Similarly, liver fibrosis was significantly reduced in PAR-1(-/-) mice fed an ANIT diet. Hepatic integrin β6 mRNA induction, expression of αVβ6 protein by intrahepatic BDECs, and SMAD2 phosphorylation were reduced by TF deficiency and PAR-1 deficiency in mice fed the ANIT diet. Treatment with either an anti-αVβ6 blocking antibody or soluble transforming growth factor-β receptor type II reduced liver fibrosis in mice fed the ANIT diet. PAR-1 activation enhanced transforming growth factor-β1-induced integrin β6 mRNA expression in both transformed human BDECs and primary rat BDECs. Interestingly, TF and PAR-1 mRNA levels were increased in livers from patients with cholestatic liver disease. These results indicate that a TF-PAR-1 pathway contributes to liver fibrosis induced by chronic cholestasis by increasing expression of the αVβ6 integrin, an important regulator of transforming growth factor-β1 activation.

Intracellular B7-H4 Suppresses Bile Duct Epithelial Cell Apoptosis in Human Primary Biliary Cirrhosis

The expression and function of B7-H4, a recently identified co-inhibitory molecule of the B7 superfamily, in the pathogenesis of primary biliary cirrhosis (PBC) is still unclear. Here the expression of B7-H4 in sections from PBC patients (n = 16) was examined by immunohistochemistry and it was detected in primary bile duct epithelial cells (BECs) which were isolated from PBC patients by flow cytometry (FACs). Moreover, we also analyzed BECs-associated B7-H4 function through knock-down of its expression via RNA interference (RNAi) in vitro. Immunohistochemistry and FACs evidenced that the expression of B7-H4 was restricted in the cytoplasm of BECs from PBC patients, while it was completely absent in normal liver tissues. The cytoplasmic B7-H4 gene was cloned, and sequenced analysis showed it was encoded by the same gene to the membrane B7-H4. Interesting, silencing B7-H4 by specific RNAi resulted in enhanced FasL expression and BEC apoptosis. Conversely, interruption of Fas\FasL interaction with using FasL blocking antibodies (clone 4H9) reversed cell apoptosis. Our results suggested that the intracellular B7-H4 appears to prevent Fas/FasL-mediated BEC apoptosis during the progression of PBC, and indicates B7-H4 is a possible target for therapeutic intervention of this disease.

Rabbit Tularemia and Hepatic Coccidiosis in Wild Rabbit

Rabbit Tularemia and Hepatic Coccidiosis in Wild Rabbit

A novel method for establishment and characterization of extrahepatic bile duct epithelial cells from mice

Culture of extrahepatic bile duct epithelial cells is a useful model to investigate physiology of extrahepatic bile duct epithelia and hepatobiliary disease mechanisms. The aim of this work was to establish and characterize a primary murine extrahepatic bile duct epithelial cell culture. Epithelial cells were isolated from extrahepatic bile ducts of BALB/c mice that were intraperitoneally injected with newborn bovine serum to induce the proliferation of extrahepatic bile ducts' epithelial cells and cultured on rat tail type I collagen-coated plastic culture flask containing DMEM/HamF12 with 10% FBS and 10 ng/ml epidermal growth factor at 37°C in an incubator with 5% humidified CO(2). The cells showed typical morphologic characteristics of epithelial phenotypes with cobblestone appearance in monolayer within 5-6 d after culture; they were positive against anticytokeratin-19 immunostaining. Transmission electron microscopy showed typical bile duct epithelia with microvilli on the cytomembrane, Golgi complex, massive mitochondria, and rough endoplasmic reticulum in the cytoplasmic. The growth curve of the epithelial cells was determined by a MTT assay which showed a normal sigmoidal growth curve. This culture technique might be a reliable method for isolation, purification, and primary culture of extrahepatic bile duct epithelial cells that can serve as a model for in vitro studies on the pathophysiology of hepatobiliary diseases as well as pharmacological and toxicological targets relevant to hepatobiliary diseases.

Construct Double Reporter Vector Enhanced by CK19 Promoter and Its Application in Differentiation of Hepatic Progenitor Cells*

Liver progenitor cells are co-precursor cells of hepatic cells and bile duct epithelial cells, a reporter gene was used to research the differentiation of liver progenitor cells. First of all, the cytokeratin 19 promoter segment was cloned from hepatocellular carcinoma cell line HepG2 and then following the promoter a renilla luciferase and a red fluorescence protein's fusion gene were inserted to finish the double report lentiviral vector. Second, the liver progenitor cells were transducted with lentivirus, and then GFP positive cells were enriched by flow cytometry sorting. Third, the GFP positive liver progenitor cells were co-cultured with PT67 cells which could express the molecule-epimorphin for 5 days. Then, it was found that the stable transducted liver progenitor cells' shape were not only transformed and arranged as cord like structure, but also renilla luciferase and red fluorescence protein which enhanced by CK19 promoter were detected. So, these results proved that the liver progenitor cells had been induced to bile duct epithelial cells. The vector enhanced by CK19 promoter can monitor the differentiation of liver progenitor cells in different environment. In a word, this lentivirus vector can help us study the differentiation mechanism of liver progenitor cells, and scan the molecules which can do a help in differentiation.

NF-κB related abnormal hyper-expression of iNOS and NO correlates with the inflammation procedure in biliary atresia livers

To study the expression of inducible nitric oxide synthase (iNOS) and its related regulators in biliary atresia (BA) livers and exlpore their relationships with the inflammation pathway in BA livers. The iNOS expression in livers of 38 cases of BA children, 15 cases of neonatal cholestasis (NC) children, and 18 cases of normal control were, respectively, examined and total nitric oxide (NO) metabolites concentration of all samples were calculated by a colorimetric method based on Griess reaction. The TdT-mediated dupt biotin nick end labeling (TUNEL) method was used to label the apoptotic bile duct epithelial cells and hepatocytes. The western blotting and immunohistochemistry methods to semi-quantitatively analyze the nuclear factor-kappaB (NF-kappaB) expression of each group were also used. The iNOS expression intensity and total NO metabolites concentration of BA group (0.30 +/- 0.08, 90.40 +/- 12.46 micromol/L) were significantly higher than those of NC and normal control groups, P < 0.01. Correlation analysis showed a strong positive correlation between the serum AST level (152.76 +/- 29.59 U/L) and total NO metabolites concentration in BA group. Compared with the NC (32.47 +/- 5.55) and normal control (20.72 +/- 5.63) groups, a significantly higher apoptosis rate of intrahepatic bile duct epithelial cells was found in BA group (54.00 +/- 11.67) that tightly correlated with the iNOS intensity (r = 0.99, P < 0.01). The NF-kappaB intensity of BA group was also significantly higher than that of NC and normal control groups and had a strong positive correlation with the iNOS intensity (r = 0.97, P < 0.01). The abnormal hyper-expression of iNOS may play an important role in mediating the inflammation procedure in BA livers. This change perhaps has some relationship with the high expression of NF-kappaB and NO. These regulators can up-regulate the apoptosis of bile duct epithelial cells in BA livers and cause the damage to liver tissues.

Role of Cholangiocyte Bile Acid Transporters in Large Bile Duct Injury After Rat Liver Transplantation

The pathogenesis of nonanastomotic strictures with a patent hepatic artery remains to be investigated. This study focuses on the role of cholangiocyte bile acid transporters in bile duct injury after liver transplantation. Sprague-Dawley rats were divided into three groups (n=20 for each): the sham-operated group (Sham), the transplant group with 1-hr donor liver cold preservation (CP-1h), and the transplant group with 12-hr donor liver cold preservation (CP-12h). Bile was collected for biochemical analysis. The histopathologic evaluation of bile duct injury was performed and the cholangiocyte bile acid transporters apical sodium-dependent bile acid transporter (ASBT), ileal lipid binding protein (ILBP), and Ostalpha/Ostbeta were investigated. RESULTS.: The immunohistochemical assay suggested that ASBT and ILBP were expressed exclusively on large bile duct epithelial cells, whereas Ostalpha and Ostbeta were expressed on both small and large bile ducts. Western blot and quantitative polymerase chain reaction analysis showed that the expression levels of these transporters dramatically decreased after transplantation. It took seven to 14 days for ILBP, Ostalpha, and Ostbeta to recover, whereas ASBT recovered within 3 days and even reached a peak above the normal level seven days after operation. In the CP-12h group, the ratios of the ASBT/ILBP, ASBT/Ostalpha and ASBT/Ostbeta expression levels were correlated with the injury severity scores of large but not small bile ducts. The results suggest that the unparallel alteration of cholangiocyte bile acid transporters may play a potential role in large bile duct injury after liver transplantation with prolonged donor liver preservation.

Accumulation of neoplastic traits prior to spontaneous in vitro transformation of rat cholangiocytes determines susceptibility to activated ErbB-2/Neu

Cholangiocarcinoma, a severe form of biliary cancer, has a high mortality rate resulting partially from the advanced stage of disease at earliest diagnosis. A better understanding of the progressive molecular and cellular changes occurring during spontaneous cholangiocarcinogenesis is needed to identify potential biomarkers for diagnosis/prognosis or targets for novel therapeutics. Here, we show that with continued passage (p) in vitro, rat bile duct epithelial cells (BDEC) accumulated neoplastic characteristics that by mid-passage (p31-85) included alterations in morphology, increased growth rate, growth factor independence, decreased cell adhesion, loss of cholangiocyte markers expressed at low passage (p < 30), and onset of aneuploidy. At high passage (p > 85), BDEC cultures showed increasing numbers of cells expressing activated, tyrosine phosphorylated ErbB-2/Neu, a receptor tyrosine kinase previously reported to be at elevated levels in cholangiocarcinomas. Enrichment for high passage ErbB-2/Neu-positive cells yielded several anchorage-independent sub-lines with elevated levels of activated ErbB-2/Neu and increased expression of cyclooxygenase-2 (COX-2). When injected into immunodeficient beige/nude/xid mice, these sub-lines formed poorly differentiated cystic tumors strongly positive for rat cholangiocyte markers, a finding consistent with a previous report showing the susceptibility of high passage, non-tumorigenic BDEC to transformation by activated ErbB-2/Neu. Mid passage BDEC, in contrast, were resistant to the transforming activity of activated ErbB-2/Neu and remained anchorage dependent in vitro and non-tumorigenic in vivo following stable transfection. Based on these findings, we concluded that during progression to high passage, cultured BDEC undergo preneoplastic changes that enhance their susceptibility to transformation by ErbB-2/Neu. The ability to generate cells at different points in the process of spontaneous neoplastic transformation offers a valuable model system for identifying molecular features that determine whether over-expression of activated ErbB-2/Neu is necessary and sufficient to induce neoplastic conversion.

Expression of CYP1C1 and CYP1A in Fundulus heteroclitus during PAH-induced carcinogenesis

CYP1C1 is a relatively newly identified member of the cytochrome P450 family 1 in teleost fish. However, CYP1C1's expression and physiological roles relative to the more recognized CYP1A in polycyclic aromatic hydrocarbons (PAHs) induced toxicities are unclear. Fundulus heteroclitus fry were exposed at 6–8 days post-hatch (dph) and again at 13–15 dph for 6 h to dimethyl sulfoxide (DMSO) control, 5 mg/L benzo[ a]pyrene (BaP), or 5 mg/L dimethylbenzanthracene (DMBA). Fry were euthanized at 0, 6, 18, 24 and 30 h after the second exposure. In these groups, both CYP1A and CYP1C1 protein expression were induced within 6 h after the second exposure. Immunohistochemistry (IHC) results from fry revealed strongest CYP1C1 expression in renal tubular and intestinal epithelial cells. Additional fish were examined for liver lesions 8 months after initial exposure. Gross lesions were observed in 20% of the BaP and 35% of the DMBA-treated fish livers. Histopathologic findings included foci of cellular alteration and neoplasms, including hepatocellular adenoma, hepatocellular carcinoma and cholangioma. Strong CYP1A immunostaining was detected diffusely in altered cell foci and on the invading margin of hepatocelluar carcinomas. Lower CYP1A expression was seen in central regions of the neoplasms. In contrast, CYP1C1 was only detectable and highly expressed in proliferated bile duct epithelial cells. Our CYP1C1 results suggest the potential for tissue specific CYP1C1-mediated PAH metabolism but not a more chronic role in progression to liver hepatocellular carcinoma.

LPS-Induced Epithelial-Mesenchymal Transition of Intrahepatic Biliary Epithelial Cells

Recent studies have revealed that the epithelial-mesenchymal transition (EMT) of bile duct epithelial cells is engaged in hepatic fibrogenesis. However, the association between etiological factors of liver disease such as virus or bacterial infection and EMT remains to be investigated. The present study focuses on the inductive role of endotoxin, the main component of the cell wall's ectoblast of gram-negative bacteria, in the EMT of human intrahepatic biliary epithelial cells (HIBEpiCs). The expressions of E-cadherin, S100A4, α-SMA, TGF-β1, and Smad2/3 in HIBEpiCs cultured with or without lipopolysaccharide LPS, were detected by real-time PCR and Western blotting. We blocked the expression of TGF-β1 using paclitaxel and knocked down Smad2/3 by siRNA to explore the role of TGF-β1/Smad2/3 pathway in the EMT of HIBEpiCs. Resting HIBEpiCs showed epithelioid cobblestone morphology, and underwent a phenotypic change to produce bipolar cells with a fibroblastic morphology when co-cultured with LPS. After LPS stimulation and the up-regulation of mRNA and protein expression of TGF-β1 and Smad2/Smad3, the mRNA and protein expression of mesenchymal markers (S100A and α-SMA) increased significantly. Paclitaxel inhibited the mRNA and protein expression of TGF-β1 in vitro. Knock-down of Smad2/3 by siRNA led to up-regulation of epithelial markers E-cadherin and down-regulation of S100A and α-SMA, indicating a reversal of the EMT. LPS can induce the expression of TGF-ß1 and a subsequent EMT in HIBEpiCs, and the inhibition of TGF-ß1 or Smad 2/3 could reverse this EMT, suggesting that LPS may play a potential role in the EMT of HIBEpiCs.

Triptolide and TRAIL Combination Enhances Apoptosis in Cholangiocarcinoma

Cholangiocarcinoma originates from bile duct epithelial cells in the intrahepatic and extrahepatic biliary system. We recently observed that triptolide (a diterpenoid triepoxide) is effective in inducing apoptosis in pancreatic tumors. Death receptors 4 and 5 are overexpressed in several cancer types, and their activation by tumor-necrosis factor-related apoptosis-inducing ligand (TRAIL) induces cell death. The principal objective of this study was to determine the effects of combination therapy with TRAIL and triptolide in cholangiocarcinoma. Two cholangiocarcinoma cell lines were incubated with various doses of triptolide and TRAIL, alone and in combination; cell viability was assessed at 24 and 48 h. Annexin-V staining and caspase-3 activity were measured after 24 h of triptolide, TRAIL or combination treatment. Western blots assessed protein levels of poly(ADP-ribose) polymerase (PARP) and X-linked inhibitor of apoptosis (XIAP). Combination treatment using TRAIL and triptolide decreased cell viability in all cell lines at 48 h, with greater cell killing than that which was observed with either drug alone. This decrease in viability was associated with increases in annexin-V staining and caspase-3 activity. Western blot analysis demonstrated increases in PARP cleavage and decreases in XIAP expression that were dose-dependent. TRAIL and triptolide in combination decreased cell viability and enhanced apoptosis. Furthermore, Western blot analysis suggests that triptolide sensitizes cells to TRAIL-induced apoptotic cell death by inhibiting expression of XIAP, a protein known to inhibit apoptosis. Our results demonstrate that combination of TRAIL and triptolide enhance apoptosis in cholangiocarcinoma cell lines.

Neutrophil Depletion Blocks Early Collagen Degradation in Repairing Cholestatic Rat Livers

Biliary obstruction results in a well-characterized cholestatic inflammatory and fibrogenic process; however, the mechanisms and potential for liver repair remain unclear. We previously demonstrated that Kupffer cell depletion reduces polymorphonuclear cell (neutrophil) (PMN) and matrix metalloproteinase (MMP)8 levels in repairing liver. We therefore hypothesized that PMN-dependent MMP activity is essential for successful repair. Male Sprague-Dawley rats received reversible biliary obstruction for 7 days, and the rat PMN-specific antibody RP3 was administered 2 days before biliary decompression (repair) and continued daily until necropsy, when liver underwent morphometric analysis, immunohistochemistry, quantitative RT-PCR, and in situ zymography. We found that RP3 treatment did not reduce Kupffer cell or monocyte number but significantly reduced PMN number at the time of decompression and 2 days after repair. RP3 treatment also blocked resorption of type I collagen. In addition, biliary obstruction resulted in increased expression of MMP3, MMP8, and tissue inhibitor of metalloproteinase 1. Two days after biliary decompression, both MMP3 and tissue inhibitor of metalloproteinase 1 expression declined toward sham levels, whereas MMP8 expression remained elevated and was identified in bile duct epithelial cells by immunohistochemistry. PMN depletion did not alter the hepatic expression of these genes. Conversely, collagen-based in situ zymography demonstrated markedly diminished collagenase activity following PMN depletion. We conclude that PMNs are essential for collagenase activity and collagen resorption during liver repair, and speculate that PMN-derived MMP8 or PMN-mediated activation of intrinsic hepatic MMPs are responsible for successful liver repair.

Recent advances in the regulation of cholangiocyte proliferation and function during extrahepatic cholestasis

Bile duct epithelial cells (i.e., cholangiocytes), which line the intrahepatic biliary epithelium, are the target cells in a number of human cholestatic liver diseases (termed cholangiopathies). Cholangiocyte proliferation and death is present in virtually all human cholangiopathies. A number of recent studies have provided insights into the key mechanisms that regulate the proliferation and function of cholangiocytes during the pathogenesis of cholestatic liver diseases. In our review, we have summarised the most important of these recent studies over the past 3 years with a focus on those performed in the animal model of extrahepatic bile duct ligation. In the first part of the review, we provide relevant background on the biliary ductal system. We then proceed with a general discussion of the factors regulating biliary proliferation performed in the cholestatic animal model of bile duct ligation. Further characterisation of the factors that regulate cholangiocyte proliferation and function will help in elucidating the mechanisms regulating the pathogenesis of biliary tract diseases in humans and in devising new treatment approaches for these devastating diseases.

Epithelial-Mesenchymal Transitions of Bile Duct Epithelial Cells in Primary Hepatolithiasis

The purpose of this study was to explore the role of epithelial-mesenchymal transition in the pathogenesis of hepatolithiasis. Thirty-one patients with primary hepatolithiasis were enrolled in this study. Expressions of E-cadherin, α-catenin, α-SMA, vimentin, S100A4, TGF-β1 and P-smad2/3 in hepatolithiasis bile duct epithelial cells were examined by immunohistochemistry staining. The results showed that the expressions of the epithelial markers E-cadherin and α-catenin were frequently lost in hepatolithiasis (32.3% and 25.9% of cases, respectively), while the mesenchymal markers vimentin, α-SMA and S100A4 were found to be present in hepatolithiasis (35.5%, 29.0%, and 32.3% of cases, respectively). The increased mesenchymal marker expression was correlated with decreased epithelial marker expression. The expressions of TGF-β1 and P-smad2/3 in hepatolithiasis were correlated with the expression of S100A4. These data indicate that TGF-β1-mediated epithelial-mesenchymal transition might be involved in the formation of hepatolithiasis.

PBK/TOPK in the differential diagnosis of cholangiocarcinoma from hepatocellular carcinoma and its involvement in prognosis of human cholangiocarcinoma

The increased expression of PDZ binding kinase/lymphokine-activated killer T-cell-originated protein kinase (PBK/TOPK) is associated with some human malignant tumors. In this study, we analyzed PBK/TOPK expression in hepatic primary tumor and explored its role in cholangiocarcinoma biology. Seventy-four cholangiocarcinomas, 33 hepatocellular carcinomas, and 10 normal liver tissues were prepared from paraffin-embedded specimens. PBK/TOPK protein was assessed by immunohistochemical staining, and the survival time was analyzed with the Kaplan-Meier method. The protein, mRNA of PBK/TOPK, and cell cycle of cholangiocarcinoma cell line after PBK/TOPK suppression with small interfere RNA were studied by Western blot, semiquantitative reverse transcriptase-polymerase chain reaction, and flow cytometry, respectively. PBK/TOPK was usually expressed in normal bile duct epithelial cells and much more frequently expressed in cholangiocarcinoma (68/74) but never expressed in hepatocytes and hepatocellular carcinomas (0/33). PBK/TOPK down-regulation was related to the poor prognosis of patients with cholangiocarcinoma (P = .013). Epidermal growth factor can enhance PBK/TOPK expression in cholangiocarcinoma QBC 939 cells, but suppression of PBK/TOPK in the cells did not affect their proliferation. PBK/TOPK protein could serve as a useful indicator for histopathologic differentiation between cholangiocarcinoma and hepatocellular carcinomas and the low expression of PBK/TOPK is predicative of poor survival in cholangiocarcinoma patients.

Colic Caused by Panicum Maximum Toxicosis in Equidae in Northern Brazil

In the Amazon region of northern Brazil, Panicum maximum cultivars Mombaça, Tanzânia, and Massai cause severe colic and death in horses and mules. The disease occurs in the rainy season, when sprouting pastures are grazed by equidae. In the 8 separate disease outbreaks studied, a total of 52 out of 153 equidae were affected, including 19 that died (10 mules and 9 horses). Clinical signs were colic and abdominal dilatation, with a clinical manifestation period of 12 hr to 4 days. Serum activities of gamma-glutamyl transferase and aspartate aminotransferase were within reference intervals; however, serum urea nitrogen and creatinine concentrations were occasionally elevated. The primary gross and histologic lesions were observed in the digestive system. The stomach, small intestine, and large intestine had severe hemorrhages and occasional mucosal erosions and ulcerations. Ulceration and hemorrhage of the urinary bladder were rarely observed. Histologic examination revealed diffuse lymphoplasmacytic gastritis and enteritis with severe congestion, hemorrhage, and occasional epithelial necrosis and ulceration. Lymphocellular necrosis was occasionally observed within gut-associated lymphoid tissue. Tubular nephrosis occurred in some animals. Degeneration and occasional necrosis of bile duct epithelial cells and degeneration of hepatocytes were observed in the liver. Toxic pastures were negative for diosgenin- and yamogenin-based saponins, and oxalate concentrations were within reference intervals for the species. The toxin or toxins causing disease and the reason for the toxicity of the plant in the northern region are unknown.

Curcumin reduces oxidative and nitrative DNA damage through balancing of oxidant–antioxidant status in hamsters infected with Opisthorchis viverrini

Opisthorchis viverrini (OV) infection is endemic in northeastern Thailand. We have previously reported that OV infection induces oxidative and nitrative DNA damage via chronic inflammation, which contributes to the disease and cholangiocarcinogenesis. Here, we examined the effect of curcumin, an antioxidant, on pathogenesis in OV-infected hamsters. DNA lesions were detected by double immunofluorescence and the hepatic expression of oxidant-generating and antioxidant genes was assessed by quantitative RT-PCR analysis. Dietary 1.0% curcumin significantly decreased OV-induced accumulation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), an oxidative DNA lesion, and 8-nitroguanine, a nitrative DNA lesion, in the nucleus of bile duct epithelial and inflammatory cells. Expression of oxidant-generating genes (inducible nitric oxide synthase; iNOS, its nuclear transcriptional factor, NF-kappaB, and cyclooxygenase-2), and plasma levels of nitrate, malondialdehyde, and alanine aminotransferase, were also decreased in curcumin-treated group. In contrast, curcumin increased the mRNA expression of antioxidant enzymes (Mn-superoxide dismutase and catalase), and ferric-reducing anti-oxidant power in the plasma. In conclusion, curcumin reduced oxidative and nitrative DNA damage by suppression of oxidant-generating genes and enhancement of antioxidant genes, leading to inhibition of oxidative and nitrative stress. Therefore, curcumin may be used as a chemopreventive agent to reduce the severity of OV-associated diseases and the risk of cholangiocarcinoma (CCA).

Identification of a novel staining pattern of bile duct epithelial cells in primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is an inflammatory disease of the bile ducts with an unknown etiology. A number of autoantigens have been proposed, but an early diagnostic marker is still lacking. Our aim was to identify such an autoantigen. Immunostaining was performed on normal human bile duct with sera from patients with PSC and controls. To identify an autoantigen a cDNA library from normal human choledochus was constructed and immunoscreened with patient sera. Using in vitro transcription and translation and immunoprecipitation we examined the immunoreactivity against PDZ domain containing 1 (PDZK1) in 35 patients with PSC, 198 control patients, and 94 healthy controls. We observed a previously unpublished staining pattern in which cytoplasmatic granules and apical cell membranes of biliary epithelial cells were stained by PSC sera. Strong immunoreactivity to these structures was obtained with 12 out of 35 PSC sera (34%) but not with sera from healthy controls. By screening the cDNA library we identified PDZK1 as a candidate antigen. Immunoreactivity against PDZK1 was detected in 9% of PSC patients, 2% of inflammatory bowel disease (IBD) patients, 8% of autoimmune pancreatitis patients, 18% of Grave's disease patients, and 1% of healthy controls. Previously unpublished, specific, and strong autoantibodies against epithelial cells of the bile duct in PSC sera were identified. Furthermore, PDZK1 is suggested as a potential new autoantigen.

Monoclonal antibody to novel cell surface epitope on Hsc70 promotes morphogenesis of bile ducts in newborn rat liver

We previously described a cell surface reactive monoclonal antibody, MAb OC.10, which recognizes an epitope shared by rat fetal liver ductal cells, hepatic progenitor cells, mature cholangiocytes, and hepatocellular carcinomas (HCC). Here, intrasplenic injection of MAb OC.10 into newborn rats was shown by immunofluorescence microscopy to strongly label intrahepatic bile ducts. Furthermore, the in situ labeling of intrahepatic cholangiocytes by injecting MAb OC.10 increased the number of intraportal and intralobular bile ducts with well-defined lumens when compared to IgM-injected control animals. The antigen for MAb OC.10 was identified by mass spectrometry as Hsc70, a constitutively expressed heat shock protein belonging to the HSP70 family. Immunoblot analysis demonstrated that MAb OC.10 reacted with recombinant bovine Hsc70 protein, with protein immunoprecipitated from rat bile duct epithelial (BDE) cell lysates with monoclonal anti-Hsc70 antibody, and with Hsc70-FLAG protein over-expressed in human 293T cells. In addition, Hsc70-specific small interfering RNA reduced the amount of OC.10 antigen expressed in nucleofected BDE cells. Consistent with the specificity of MAb OC.10 for Hsc70, heat shock did not induce OC.10 expression in BDE cells, a characteristic of Hsp70. Immunofluorescence with BDE cells further suggested that MAb OC.10 binds a novel cell surface epitope of Hsc70. This was in contrast to a commercially available monoclonal anti-Hsc70 antibody that showed strong cytosolic reactivity. These findings demonstrate that presentation of the OC.10 epitope differs between cytosolic and surface forms of Hsc70 and may suggest distinct differences in protein conformation or epitope availability determined in part by protein-protein or protein-lipid interactions. Phage display and pepscan analysis mapped the epitope for MAb OC.10 to the N-terminal 340-384 amino acids of the ATPase domain of rat Hsc70. These findings suggest that MAb OC.10 recognizes an epitope on rat Hsc70 when presented on the cell surface that promotes morphogenic maturation of bile ducts in newborn rat liver. Furthermore, since we have shown previously that the OC.10 antigen is expressed on HCC subpopulations with oval cell characteristics, our current results indicate that Hsc70 has the potential to be expressed on the surface of certain tumor cells.

Cathepsin F Cysteine Protease of the Human Liver Fluke, Opisthorchis viverrini

BackgroundThe liver fluke Opisthorchis viverrini is classified as a class I carcinogen due to the association between cholangiocarcinoma and chronic O. viverrini infection. During its feeding activity within the bile duct, the parasite secretes several cathepsin F cysteine proteases that may induce or contribute to the pathologies associated with hepatobiliary abnormalities.Methodology/Principal FindingsHere, we describe the cDNA, gene organization, phylogenetic relationships, immunolocalization, and functional characterization of the cathepsin F cysteine protease gene, here termed Ov-cf-1, from O. viverrini. The full length mRNA of 1020 nucleotides (nt) encoded a 326 amino acid zymogen consisting of a predicted signal peptide (18 amino acids, aa), prosegment (95 aa), and mature protease (213 aa). BLAST analysis using the Ov-CF-1 protein as the query revealed that the protease shared identity with cathepsin F-like cysteine proteases of other trematodes, including Clonorchis sinensis (81%), Paragonimus westermani (58%), Schistosoma mansoni and S. japonicum (52%), and with vertebrate cathepsin F (51%). Transcripts encoding the protease were detected in all developmental stages that parasitize the mammalian host. The Ov-cf-1 gene, of ∼3 kb in length, included seven exons interrupted by six introns; the exons ranged from 69 to 267 bp in length, the introns from 43 to 1,060 bp. The six intron/exon boundaries of Ov-cf-1 were conserved with intron/exon boundaries in the human cathepsin F gene, although the gene structure of human cathepsin F is more complex. Unlike Ov-CF-1, human cathepsin F zymogen includes a cystatin domain in the prosegment region. Phylogenetic analysis revealed that the fluke, human, and other cathepsin Fs branched together in a clade discrete from the cathepsin L cysteine proteases. A recombinant Ov-CF-1 zymogen that displayed low-level activity was expressed in the yeast Pichia pastoris. Although the recombinant protease did not autocatalytically process and activate to a mature enzyme, trans-processing by Fasciola hepatica cathepsin L cleaved the prosegment of Ov-CF-1, releasing a mature cathepsin F with activity against the peptide Z-Phe-Arg-NHMec >50 times that of the zymogen. Immunocytochemistry using antibodies raised against the recombinant enzyme showed that Ov-CF-1 is expressed in the gut of the mature hermaphroditic fluke and also in the reproductive structures, including vitelline glands, egg, and testis. Ov-CF-1 was detected in bile duct epithelial cells surrounding the flukes several weeks after infection of hamsters with O. viverrini and, in addition, had accumulated in the secondary (small) bile ducts where flukes cannot reach due to their large size.Conclusions/SignificanceA cathepsin F cysteine protease of the human liver fluke O. viverrini has been characterized at the gene and protein level. Secretion of this protease may contribute to the hepatobiliary abnormalities, including cholangiocarcinogenesis, observed in individuals infected with this parasite.