Inflammatory markers neopterin and alanine aminotransferase in HCV patients treated with HCV NS3.4A protease inhibitor telaprevir (VX-950) and/or peginterferon alfa-2a.

Objective: Neopterin is a marker of monocyte/macrophage activity. Alanine aminotransferase (ALAT) is a marker of hepatocyte injury. The aim of this study was to determine changes in neopterin and ALAT levels, as markers of inflammation, in two ancillary studies during two-phase 1b trials of hepatitis C virus (HCV) NS3.

Prediction of virologic response in difficult-to-treat chronic hepatitis C patients during high-dose interferon induction therapy.

Objective: To determine (i) whether early viral kinetics or other markers during a modified treatment regimen are predictors of treatment outcome and (ii) whether fast responders can be treated for 24 weeks, without compromising the sustained virologic response (SVR) rate.

Material And Methods: One hundred "difficult-to-treat" chronic hepatitis C patients (46 previous non-responders/relapsers (any genotype), 54 treatment-naive patients genotypes 1 and 4) were treated with triple antiviral induction therapy: amantadine hydrochloride and ribavirin, combined with 6 weeks interferon alfa-2b induction (weeks 1-2: 18 MU/day, weeks 3-4: 9 MU/day, weeks 5-6: 6 MU/day), thereafter combined with weekly peginterferon alfa-2b. Fast responders (>or=3 log(10) HCV RNA decline at week 4) were randomized to 24 or 48 weeks.

Regulation of direct transintestinal cholesterol excretion in mice.

Biliary secretion is generally considered to be an obligate step in the pathway of excess cholesterol excretion from the body. We have recently shown that an alternative route exists. Direct transintestinal cholesterol efflux (TICE) contributes significantly to cholesterol removal in mice.

Abcg5/8 independent biliary cholesterol excretion in Atp8b1-deficient mice.

Backgrounds & Aims: ATP8B1 is a phosphatidylserine flippase in the canalicular membrane; patients with mutations in ATP8B1 develop severe chronic (PFIC1) or periodic (BRIC1) cholestatic liver disease. We have observed that Atp8b1 deficiency leads to enhanced biliary cholesterol excretion. It has been established that biliary cholesterol excretion depends on transport by the heterodimer Abcg5/Abcg8.

[A 47-year-old dog breeder with chronic polyarthritis, weight loss and high fever].

A 47-year-old dog breeder had suffered from unclassified polyarthritis for four years. During immunomodulatory therapy of an assumed seronegative chronic polyarthritis with Leflunomid and Adalimumab he developed severe systemic inflammatory disease with high fever, weight loss, and severe arthralgia. Fever and arthralgias temporarily improved under antibiotic therapy, although a causative organism had not been found.

Alteration of viral lipid composition by expression of the phospholipid floppase ABCB4 reduces HIV vector infectivity.

Background: The presence of cholesterol in the Human Immunodeficiency Virus (HIV) lipid envelop is important for viral function as cholesterol depleted viral particles show reduced infectivity. However, it is less well established whether other viral membrane lipids are also important for HIV infection. The ABCB4 protein is a phosphatidyl choline (PC) floppase that mediates transport of PC from the inner to the outer membrane leaflet.

ATP8B1 requires an accessory protein for endoplasmic reticulum exit and plasma membrane lipid flippase activity.

Unlabelled: Mutations in ATP8B1 cause progressive familial intrahepatic cholestasis type 1 and benign recurrent intrahepatic cholestasis type 1. Previously, we have shown in mice that Atp8b1 deficiency leads to enhanced biliary excretion of phosphatidylserine, and we hypothesized that ATP8B1 is a flippase for phosphatidylserine. However, direct evidence for this function is still lacking.

Direct intestinal cholesterol secretion contributes significantly to total fecal neutral sterol excretion in mice.

Background & Aims: Hepatobiliary secretion is generally believed to be an integral step in the pathway of cholesterol excretion from the body. Here we have investigated the validity of this paradigm in mice.

Methods: Cholesterol balance was assessed by measuring intake, excretion, and biliary output in different mouse models.

Transporters in the intestine limiting drug and toxin absorption.

The pharmacokinetic behaviour of drugs strongly depends on transporters in intestine and liver. The extent of absorption in the intestine depends on diffusion across the mucosa as well as transporter-mediated uptake across the apical membrane of enterocytes. Efflux pumps in this membrane may strongly reduce the extent of net uptake.

Monocyte-derived dendritic cells from chronic HCV patients are not infected but show an immature phenotype and aberrant cytokine profile.

Background: Chronic hepatitis C virus (HCV) infection is characterized by an insufficient immune response, possibly owing to impaired function of antigen-presenting cells such as myeloid dendritic cells (DCs). Therapeutic vaccination with in vitro generated DCs may enhance the immune response. Subsets of DCs can originate from monocytes, but the presence of HCV in monocytes that develop into DCs in vitro may impair DC function.

Preferential gene transfer of lentiviral vectors to liver-derived cells, using a hepatitis B peptide displayed on GP64.

One of the problems that limit the efficiency of viral gene therapy is the lack of specificity of viral particle binding. The development of techniques to target viral particles to specific cell types is therefore important. Because GP64 can efficiently pseudotype lentiviral vectors, we investigated the possibility of using GP64 for lentiviral vector particle targeting.

Glutamine synthetase is essential in early mouse embryogenesis.

Glutamine synthetase (GS) is expressed in a tissue-specific and developmentally controlled manner, and functions to remove ammonia or glutamate. Furthermore, it is the only enzyme that can synthesize glutamine de novo. Since congenital deficiency of GS has not been reported, we investigated its role in early development.

Intestinal bile salt absorption in Atp8b1 deficient mice.

Background/aims: Mutations in the ATP8B1 gene can cause Progressive Familial Intrahepatic Cholestasis type 1. We have previously reported that Atp8b1(G308V/G308V) mice, a model for PFIC1, have slightly, but significantly, higher baseline serum bile salt (BS) concentrations compared to wt mice. Upon BS feeding, serum BS concentrations strongly increased in Atp8b1-deficient mice.

cyclicAMP and glucocorticoid responsiveness of the rat carbamoylphosphate synthetase gene requires the interplay of upstream regulatory units.

Many genes involved in metabolic processes are regulated by glucocorticoids and/or cyclicAMP. The hepatic expression of the urea cycle enzyme carbamoylphosphate-synthetase-I gene (CPS) is regulated at the transcriptional level by both factors. Here, we report that the 5' half of the distal enhancer is necessary and sufficient for full cyclicAMP responsiveness.

In vitro functionality of human fetal liver cells and clonal derivatives under proliferative conditions.

Mature human hepatocytes are not suitable for large-scale in vitro applications that rely on hepatocyte function, due to their limited availability and insufficient proliferation capacity in vitro. In contrast, human fetal liver cells (HFLC) can be easily expanded in vitro. In this study we evaluated the hepatic function of HFLCs under proliferative conditions, to determine whether HFLCs can replace mature hepatocytes for in vitro applications.

Hepatic HNF4alpha deficiency induces periportal expression of glutamine synthetase and other pericentral enzymes.

Unlabelled: In liver, most genes are expressed with a porto-central gradient. The transcription factor hepatic nuclear-factor4alpha (HNF4alpha) is associated with 12% of the genes in adult liver, but its involvement in zonation of gene expression has not been investigated. A putative HNF4alpha-response element in the upstream enhancer of glutamine synthetase (GS), an exclusively pericentral enzyme, was protected against DNase-I and interacted with a protein that is recognized by HNF4alpha-specific antiserum.

Hepatocyte-specific interplay of transcription factors at the far-upstream enhancer of the carbamoylphosphate synthetase gene upon glucocorticoid induction.

Carbamoylphosphate synthetase-I is the flux-determining enzyme of the ornithine cycle, and neutralizes toxic ammonia by converting it to urea. An 80 bp glucocorticoid response unit located 6.3 kb upstream of the transcription start site mediates hormone responsiveness and liver-specific expression of carbamoylphosphate synthetase-I.

Increased serum concentrations of secondary bile salts during cholate feeding are due to coprophagy. A study with wild-type and Atp8b1-deficient mice.

Coprophagy (i.e., consumption of feces) is a behavior seen in rodents and other animal species.

The 3'-UTR of the glutamine-synthetase gene interacts specifically with upstream regulatory elements, contains mRNA-instability elements and is involved in glutamine sensing.

Glutamine synthetase (GS) is expressed at various levels in a wide range of tissues, suggesting that a complex network of modules regulates its expression. We explored the interactions between the upstream enhancer, regulatory regions in the first intron, and the 3'-untranslated region and immediate downstream genomic sequences of the GS gene (the GS "tail"), and compared the results with those obtained previously in conjunction with the bovine growth hormone (bGH) tail. The statistical analysis of these interactions revealed that the GS tail was required for full enhancer activity of the combination of the upstream enhancer and either the middle or the 3'-intron element.

The mechanism of ABCG5/ABCG8 in biliary cholesterol secretion in mice.

The main player in biliary cholesterol secretion is the heterodimeric transporter complex, ABCG5/ABCG8, the function of which is necessary for the majority of sterols secreted into bile. It is not clear whether the primary step in this process is flopping of cholesterol from the inner to the outer leaflet of the canalicular membrane, with desorption by mixed micelles, or decreasing of the activation energy required for cholesterol desorption from the outer membrane leaflet. In this study, we investigated these mechanisms by infusing Abcg8(+/+), Abcg8(+/-), and Abcg8(-/-) mice with hydrophilic and hydrophobic bile salts.

New insights in the pathogenesis of non-alcoholic fatty liver disease.

Purpose Of Review: The hallmark of non-alcoholic fatty liver disease is hepatic steatosis. This is mostly a benign condition, but for largely unknown reasons it progresses to liver fibrosis, cirrhosis, and ultimately hepatocellular carcinoma in about 10% of patients. In this review we discuss recent progress in the understanding of the etiology of non-alcoholic fatty liver disease.

Assessment of in Vitro Applicability of Reversibly Immortalized NKNT-3 Cells and Clonal Derivatives.

In vitro applications of human hepatocytes, such as bioartificial livers and toxicity assays, require thoroughly testing of human cell lines prior to using them as alternative cell sources. The reversibly immortalized NKNT-3 cell line was reported to show clear in vivo functionality. Here, NKNT-3 cells were tested for their in vitro applicability.

Function and pathophysiological importance of ABCB4 (MDR3 P-glycoprotein).

Like several other ATP-binding cassette (ABC) transporters, ABCB4 is a lipid translocator. It translocates phosphatidylcholine (PC) from the inner to the outer leaflet of the canalicular membrane of the hepatocyte. Its function is quite crucial as evidenced by a severe liver disease, progressive familial intrahepatic cholestasis type 3, which develops in persons with ABCB4 deficiency.

Transcriptional profiling reveals novel markers of liver fibrogenesis: gremlin and insulin-like growth factor-binding proteins.

Activated hepatic stellate cells (HSC) that transdifferentiate to myofibroblasts in the injured liver are responsible for scar formation that leads to fibrosis and eventually cirrhosis. To investigate the gene expression profile during different stages of this process, we performed serial analysis of gene expression, representing a quantitative and qualitative description of all expressed genes. Stellate cells were isolated from human livers and cultured.

Hepatocanalicular transport defects: pathophysiologic mechanisms of rare diseases.

The apical membrane of the hepatocyte fulfils a unique function in the formation of primary bile. For all important biliary constituents a primary active transporter is present that extrudes or translocates its substrate toward the canalicular lumen. Most of these transporters are ATP-binding cassette (ABC) transporters.