Ruth Joplin

Does a betaretrovirus infection trigger primary biliary cirrhosis

Patients with primary biliary cirrhosis develop progressive ductopenia associated with the production of antimitochondrial antibodies that react with a protein aberrantly expressed on biliary epithelial cells and peri-hepatic lymph nodes. Although no specific microbe has been identified, it is thought that an infectious agent triggers this autoimmune liver disease in genetically predisposed individuals. Previous serologic studies have provided evidence to suggest a viral association with primary biliary cirrhosis. Here we describe the identification of viral particles in biliary epithelium by electron microscopy and the cloning of exogenous retroviral nucleotide sequences from patients with primary biliary cirrhosis. The putative agent is referred to as the human betaretrovirus because it shares close homology with the murine mammary tumor virus and a human retrovirus cloned from breast cancer tissue. In vivo, we have found that the majority of patients with primary biliary cirrhosis have both RT-PCR and immunohistochemistry evidence of human betaretrovirus infection in lymph nodes. Moreover, the viral proteins colocalize to cells demonstrating aberrant autoantigen expression. In vitro, we have found that lymph node homogenates from patients with primary biliary cirrhosis can induce autoantigen expression in normal biliary epithelial cells in coculture. Normal biliary epithelial cells also develop the phenotypic manifestation of primary biliary cirrhosis when cocultivated in serial passage with supernatants containing the human betaretrovirus or the murine mammary tumor virus, providing a model to test Kochs postulates in vitro.

Human intrahepatic biliary epithelial cells proliferate in vitro in response to human hepatocyte growth factor.

In previous studies, intrahepatic human biliary epithelial cells (BEC) were isolated in high purity. However, these cells demonstrated only limited growth responses. Here we report that human BEC proliferate in response to human hepatocyte growth factor (hHGF), retain BEC-specific phenotype, and can be serially passaged. BEC showed dose-dependent growth in response to 0.01-100 ng/ml hHGF. The maximum S-phase labeling index reached 40% with half-maximal stimulation at 1 ng/ml. The response of cells from normal and primary biliary cirrhotic liver to hHGF was similar. Cultures were immunostained with specific antibodies and then processed for [3H]thymidine autoradiography. Proliferating cells expressed BEC-specific markers (HEA125 and CK-19), but were negative for desmin and factor VIII-related antigen. Occasional vimentin-positive cells were observed, but these were nonproliferative. In conclusion, cells responding to hHGF were clearly BEC in origin. The observation that HGF is mitogenic for BEC as well as hepatocytes has important implications. First, greater yields of intrahepatic BEC are available for subsequent studies of the pathogenesis and etiology of diseases of the biliary epithelium. Secondly, some means of regulating the cellular response to HGF in vivo must operate, in that HGF levels rise early after partial hepatectomy and yet BEC proliferate 24 h later than hepatocytes.

Effects of angiogenic factor overexpression by human and rodent cholangiocytes in polycystic liver diseases.

Liver involvement in autosomal dominant polycystic kidney disease (ADPKD) is characterized by altered remodeling of the embryonic ductal plate (DP) with presence of biliary cysts and aberrant portal vasculature. The genetic defect causing ADPKD has been identified, but mechanisms of liver cyst growth remain uncertain. To investigate the possible role of angiogenic mechanisms, we have studied the immunohistochemical expression of vascular endothelial growth factor (VEGF), angiopoietin–1 (Ang‐1), angiopoietin‐2 (Ang‐2) and their receptors (VEGFR‐1, VEGFR‐2, Tie‐2) in ADPKD, Carolis disease, normal and fetal livers. In ADPKD and control livers Ang‐1 and Ang‐2 gene expression was studied by real‐time‐PCR. Effects of VEGF on cholangiocyte proliferation were studied by PCNA Western Blot in isolated rat cholangiocytes and by MTS assay in cultured cholangiocytes isolated from ADPKD patients and from an ADPKD mouse model (Pkd2WS25/−). Cholangiocytes were strongly positive for VEGF, VEGFR‐1, VEGFR‐2 and Ang‐2 in ADPKD and Caroli, and also for Ang‐1 and Tie‐2 in ADPKD, similar to fetal ductal plate cells. VEGF stimulated proliferation in both normal and ADPKD cholangiocytes, but the effect was particularly evident in the latter. Ang‐1 alone had no effect, but was synergic to VEGF. VEGF expression on cholangiocytes positively correlated with microvascular density. In conclusion, consistent with the immature phenotype of the cystic epithelium, expression of VEGF, VEGFRs, Ang‐1 and Tie‐2 is strongly upregulated in cholangiocytes from polycystic liver diseases. VEGF and Ang‐1 have autocrine proliferative effect on cholangiocyte growth and paracrine effect on portal vasculature, thus promoting the growth of the cysts and their vascular supply. (HEPATOLOGY 2006;43:1001–1012.)

Characterization and Isolation of Ductular Cells Coexpressing Neural Cell Adhesion Molecule and Bcl-2 from Primary Cholangiopathies and Ductal Plate Malformations

It has recently been shown that reactive bile ductules display neuroendocrine features, including immunoreactivity for the neural cell adhesion molecule (NCAM). In this study we have compared the immunohistochemical expression of NCAM with that of HEA-125 (biliary specific) and LKM-1 (hepatocyte specific) and other markers relevant to morphogenesis (Bcl-2, EMA) and cell proliferation (Ki-67) in cryostat sections from different chronic liver diseases and from fetal livers at different gestational ages. In parallel, viable NCAM-positive ductular cells were purified from collagenase digests of cirrhotic livers by immunomagnetic separation and characterized by immunocytochemistry and transmission electron microscopy. We demonstrated that reactive ductules with atypical morphology coexpressed NCAM and Bcl-2 and were found mainly in congenital diseases associated with ductal plate malformation and in primary cholangiopathies. On the contrary, reactive ductules with typical morphology were negative for NCAM/Bcl-2 and positive for EMA. Reactive ductules coexpressing NCAM/Bcl-2 were negative for the proliferation marker Ki-67 and appeared to be directly connected with periportal hepatocytes. In fetal livers NCAM/Bcl-2 was transiently expressed during the early developmental stages of ductal plate (10-16 weeks) and started to disappear as the ductal plate began duplicating. NCAM-positive ductal plate cells were Ki-67 negative, becoming positive in duplicated segments. Thus the histogenesis of ductular reactive cells seems to recapitulate the early stages of biliary ontogenesis. In primary cholangiopathies and ductal plate malformations, these cells do not appear to maturate further, and thus abundant ductular structures coexist with vanishing mature ducts. These NCAM-positive ductular cells were immunopurified from patients with chronic cholestatic liver diseases and showed ultrastructural features consistent with a less differentiated phenotype than mature cholangiocytes. These isolated cells represent a useful model for in vitro studies.

Immuno-isolation and culture of biliary epithelial cells from normal human liver

SummaryBiliary epithelial cells (BEC) lining the intra-hepatic biliary ducts are the site of damage in several immunologically mediated liver diseases. BEC are difficult to isolate since they represent only 5% of the total cell number in normal liver. In this communication, a novel method for their isolation from normal liver is presented using a monoclonal antibody (HEA125) with specificity for an epithelial cell surface glyco-protein reported to be expressed in liver only by biliary epithelium. By combining differential density centrifugation and immuno-magnetic separation using HEA125 pure BEC (105 cells/g fresh tissue) were prepared routinely. These cells were maintained in culture for up to 4 weeks with significant increases in cell numbers. The ability to prepare BEC from human liver offers an opportunity to develop In Vitro models to investigate the aetiology of diseases in intra-hepatic biliary epithelium.

Combination of ursodeoxycholic acid and glucocorticoids upregulates the AE2 alternate promoter in human liver cells.

Primary biliary cirrhosis (PBC) is a cholestatic disease associated with autoimmune phenomena and alterations in both biliary bicarbonate excretion and expression of the bicarbonate carrier AE2. The bile acid ursodeoxycholic acid (UCDA) is currently used in treatment of cholestatic liver diseases and is the treatment of choice in PBC; however, a subset of PBC patients respond poorly to UDCA monotherapy. In these patients, a combination of UDCA and glucocorticoid therapy appears to be beneficial. To address the mechanism of this benefit, we analyzed the effects of UDCA and dexamethasone on AE2 gene expression in human liver cells from hepatocyte and cholangiocyte lineages. The combination of UDCA and dexamethasone, but not UDCA or dexamethasone alone, increased the expression of liver-enriched alternative mRNA isoforms AE2b1 and AE2b2 and enhanced AE2 activity. Similar effects were obtained after replacing UDCA with UDCA conjugates. In in vitro and in vivo reporter assays, we found that a UDCA/dexamethasone combination upregulated human AE2 alternate overlapping promoter sequences from which AE2b1 and AE2b2 are expressed. In chromatin immunoprecipitation assays, we demonstrated that combination UCDA/dexamethasone treatment induced p300-related interactions between HNF1 and glucocorticoid receptor on the AE2 alternate promoter. Our data provide a potential molecular explanation for the beneficial effects of the combination of UDCA and glucocorticoids in PBC patients with inadequate response to UDCA monotherapy.

Leukemia inhibitory factor protects cholangiocarcinoma cells from drug-induced apoptosis via a PI3K/AKT-dependent Mcl-1 activation

Cholangiocarcinoma is an aggressive, strongly chemoresistant liver malignancy. Leukemia inhibitory factor (LIF), an IL-6 family cytokine, promotes progression of various carcinomas. To investigate the role of LIF in cholangiocarcinoma, we evaluated the expression of LIF and its receptor (LIFR) in human samples. LIF secretion and LIFR expression were assessed in established and primary human cholangiocarcinoma cell lines. In cholangiocarcinoma cells, we tested LIF effects on proliferation, invasion, stem cell-like phenotype, chemotherapy-induced apoptosis (gemcitabine+cisplatin), expression levels of pro-apoptotic (Bax) and anti-apoptotic (Mcl-1) proteins, with/without PI3K inhibition, and of pSTAT3, pERK1/2, pAKT. LIF effect on chemotherapy-induced apoptosis was evaluated after LIFR silencing and Mcl-1 inactivation. Results show that LIF and LIFR expression were higher in neoplastic than in control cholangiocytes; LIF was also expressed by tumor stromal cells. LIF had no effects on cholangiocarcinoma cell proliferation, invasion, and stemness signatures, whilst it counteracted drug-induced apoptosis. Upon LIF stimulation, decreased apoptosis was associated with Mcl-1 and pAKT up-regulation and abolished by PI3K inhibition. LIFR silencing and Mcl-1 blockade restored drug-induced apoptosis. In conclusion, autocrine and paracrine LIF signaling promote chemoresistance in cholangiocarcinoma by up-regulating Mcl-1 via a novel STAT3- and MAPK-independent, PI3K/AKT-dependent pathway. Targeting LIF signaling may increase CCA responsiveness to chemotherapy.

Autocrine and Paracrine Mechanisms Promoting Chemoresistance in Cholangiocarcinoma

Resistance to conventional chemotherapeutic agents, a typical feature of cholangiocarcinoma, prevents the efficacy of the therapeutic arsenal usually used to combat malignancy in humans. Mechanisms of chemoresistance by neoplastic cholangiocytes include evasion of drug-induced apoptosis mediated by autocrine and paracrine cues released in the tumor microenvironment. Here, recent evidence regarding molecular mechanisms of chemoresistance is reviewed, as well as associations between well-developed chemoresistance and activation of the cancer stem cell compartment. It is concluded that improved understanding of the complex interplay between apoptosis signaling and the promotion of cell survival represent potentially productive areas for active investigation, with the ultimate aim of encouraging future studies to unveil new, effective strategies able to overcome current limitations on treatment.

Evaluation of a new automated spotter style exam for assessment of anatomical knowledge

Skeletal material is commonly used for teaching anatomy. However, these collections are rarely used for primary research, despite their potential for student projects or more detailed anatomical investigations. Although the undocumented nature of the specimens can arguably limit study, archeologists characteristically deal with unknown skeletal material. Many methods exist to estimate age, sex, and ethnicity that could enable research. Accordingly, 94 skeletal individuals from Southampton University’s Anatomy department were assessed to determine the usability of methods routinely used in archeology. Age was estimated from degenerative joint changes and dental wear. Sexually dimorphic regions of the skull and pelvis were examined. Ethnicity was identified through craniometrics and CRANID software. As skeletons were complete, aging and sexing methods were easily applied: 95% of individuals were sexed confidently. Although all individuals were aged, often only wide estimates were produced (e.g., 21–45 years). Ethnicity however was problematic and produced less usable results. Ancestry was not determined for 19 skulls. CRANID therefore requires extremely accurate cranial measurements by a practiced researcher. This study demonstrates that archeological methods benefit anatomical research but should be selected with limitations considered. Additionally, anatomical collections are valuable teaching and research resources to osteoarcheologists who are normally limited to fragmented remains.