Publications by authors named "Ronald P Oude Elferink"

132 Publications

Efficacy of AAV8-h with Rapamycin in neonatal, suckling, and juvenile rats to model treatment in pediatric CNs patients.

Mol Ther Methods Clin Dev 2021 Mar 3;20:287-297. Epub 2020 Dec 3.

Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, AGEM, Meibergdreef 69-71, 1105 BK Amsterdam, the Netherlands.

A clinical trial using adeno-associated virus serotype 8 (AAV8)-human uridine diphosphate glucuronosyltransferase 1A1 (h) to treat inherited severe unconjugated hyperbilirubinemia (Crigler-Najjar syndrome) is ongoing, but preclinical data suggest that long-term efficacy in children is impaired due to loss of transgene expression upon hepatocyte proliferation in a growing liver. This study aims to determine at what age long-term efficacy can be obtained in the relevant animal model and whether immune modulation allows re-treatment using the same AAV vector. Neonatal, suckling, and juvenile Ugt1a1-deficient rats received a clinically relevant dose of AAV8-h, and serum bilirubin levels and anti-AAV8 neutralizing antibodies (NAbs) in serum were monitored. The possibility of preventing the immune response toward the vector was investigated using a rapamycin-based regimen with daily intraperitoneal (i.p.) injections starting 2 days before and ending 21 days after vector administration. In rats treated at postnatal day 1 (P1) or P14, the correction was (partially) lost after 12 weeks, whereas the correction was stable in rats injected at P28. Combining initial vector administration with the immune-suppressive regimen prevented induction of NAbs in female rats, allowing at least partially effective re-administration. Induction of NAbs upon re-injection could not be prevented, suggesting that this strategy will be ineffective in patients with low levels of preexisting anti-AAV NAbs.
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http://dx.doi.org/10.1016/j.omtm.2020.11.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7809245PMC
March 2021

Soluble adenylyl cyclase regulates the cytosolic NADH/NAD redox state and the bioenergetic switch between glycolysis and oxidative phosphorylation.

Biochim Biophys Acta Bioenerg 2021 Apr 5;1862(4):148367. Epub 2021 Jan 5.

Tytgat Institute for Liver and Intestinal Research, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Amsterdam Gastroenterology Endocrinology Metabolism (AGEM) Research Institute, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.

The evolutionarily conserved soluble adenylyl cyclase (sAC, ADCY10) mediates cAMP signaling exclusively in intracellular compartments. Because sAC activity is sensitive to local concentrations of ATP, bicarbonate, and free Ca, sAC is potentially an important metabolic sensor. Nonetheless, little is known about how sAC regulates energy metabolism in intact cells. In this study, we demonstrated that both pharmacological and genetic suppression of sAC resulted in increased lactate secretion and decreased pyruvate secretion in multiple cell lines and primary cultures of mouse hepatocytes and cholangiocytes. The increased extracellular lactate-to-pyruvate ratio upon sAC suppression reflected an increased cytosolic free [NADH]/[NAD] ratio, which was corroborated by using the NADH/NAD redox biosensor Peredox-mCherry. Mechanistic studies in permeabilized HepG2 cells showed that sAC inhibition specifically suppressed complex I of the mitochondrial respiratory chain. A survey of cAMP effectors revealed that only selective inhibition of exchange protein activated by cAMP 1 (Epac1), but not protein kinase A (PKA) or Epac2, suppressed complex I-dependent respiration and significantly increased the cytosolic NADH/NAD redox state. Analysis of the ATP production rate and the adenylate energy charge showed that inhibiting sAC reciprocally affects ATP production by glycolysis and oxidative phosphorylation while maintaining cellular energy homeostasis. In conclusion, our study shows that, via the regulation of complex I-dependent mitochondrial respiration, sAC-Epac1 signaling regulates the cytosolic NADH/NAD redox state, and coordinates oxidative phosphorylation and glycolysis to maintain cellular energy homeostasis. As such, sAC is effectively a bioenergetic switch between aerobic glycolysis and oxidative phosphorylation at the post-translational level.
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http://dx.doi.org/10.1016/j.bbabio.2020.148367DOI Listing
April 2021

Hepatobiliary acid-base homeostasis: Insights from analogous secretory epithelia.

J Hepatol 2021 Feb 24;74(2):428-441. Epub 2020 Oct 24.

Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands. Electronic address:

Many epithelia secrete bicarbonate-rich fluid to generate flow, alter viscosity, control pH and potentially protect luminal and intracellular structures from chemical stress. Bicarbonate is a key component of human bile and impaired biliary bicarbonate secretion is associated with liver damage. Major efforts have been undertaken to gain insight into acid-base homeostasis in cholangiocytes and more can be learned from analogous secretory epithelia. Extrahepatic examples include salivary and pancreatic duct cells, duodenocytes, airway and renal epithelial cells. The cellular machinery involved in acid-base homeostasis includes carbonic anhydrase enzymes, transporters of the solute carrier family, and intra- and extracellular pH sensors. This pH-regulatory system is orchestrated by protein-protein interactions, the establishment of an electrochemical gradient across the plasma membrane and bicarbonate sensing of the intra- and extracellular compartment. In this review, we discuss conserved principles identified in analogous secretory epithelia in the light of current knowledge on cholangiocyte physiology. We present a framework for cholangiocellular acid-base homeostasis supported by expression analysis of publicly available single-cell RNA sequencing datasets from human cholangiocytes, which provide insights into the molecular basis of pH homeostasis and dysregulation in the biliary system.
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http://dx.doi.org/10.1016/j.jhep.2020.10.010DOI Listing
February 2021

The extracellular lactate-to-pyruvate ratio modulates the sensitivity to oxidative stress-induced apoptosis via the cytosolic NADH/NAD redox state.

Apoptosis 2021 Feb 23;26(1-2):38-51. Epub 2020 Nov 23.

Tytgat Institute for Liver and Intestinal Research, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.

The advantages of the Warburg effect on tumor growth and progression are well recognized. However, the relevance of the Warburg effect for the inherent resistance to apoptosis of cancer cells has received much less attention. Here, we show here that the Warburg effect modulates the extracellular lactate-to-pyruvate ratio, which profoundly regulates the sensitivity towards apoptosis induced by oxidative stress in several cell lines. To induce oxidative stress, we used the rapid apoptosis inducer Raptinal. We observed that medium conditioned by HepG2 cells has a high lactate-to-pyruvate ratio and confers resistance to Raptinal-induced apoptosis. In addition, imposing a high extracellular lactate-to-pyruvate ratio in media reduces the cytosolic NADH/NAD redox state and protects against Raptinal-induced apoptosis. Conversely, a low extracellular lactate-to-pyruvate ratio oxidizes the cytosolic NADH/NAD redox state and sensitizes HepG2 cells to oxidative stress-induced apoptosis. Mechanistically, a high extracellular lactate-to-pyruvate ratio decreases the activation of JNK and Bax under oxidative stress, thereby inhibiting the intrinsic apoptotic pathway. Our observations demonstrate that the Warburg effect of cancer cells generates an anti-apoptotic extracellular environment by elevating the extracellular lactate-to-pyruvate ratio which desensitizes cancer cells towards apoptotic insults. Consequently, our study suggests that the Warburg effect can be targeted to reverse the lactate-to-pyruvate ratios in the tumor microenvironment and thereby re-sensitize cancer cells to oxidative stress-inducing therapies.
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http://dx.doi.org/10.1007/s10495-020-01648-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7902596PMC
February 2021

Targeting the four pillars of enterohepatic bile salt cycling; lessons from genetics and pharmacology.

Hepatology 2020 Nov 22. Epub 2020 Nov 22.

Tytgat Institute for Liver and Intestinal Research, Amsterdam UMC, University of Amsterdam, the Netherlands.

Bile salts play a pivotal role in lipid homeostasis, are sensed by specialized receptors and have been implicated in various disorders affecting the gut or liver. They may play a role either as culprit or as potential panacea. Four very efficient transporters mediate the majority of hepatic and intestinal bile salt uptake and efflux, and are each essential for the efficient enterohepatic circulation of bile salts. Starting from the intestinal lumen, conjugated bile salts cross the otherwise impermeable lipid bilayer of (mainly terminal ileal) enterocytes via the Apical Sodium-dependent Bile acid Transporter (ASBT/IBAT; gene SLC10A2) and leave the enterocyte via the basolateral heteromeric Organic Solute Transporter (OST), which consists of an alpha and beta subunit (encoded by SLC51A and SLC51B). The Na -Taurocholate Cotransporting polypeptide (NTCP; gene SLC10A1) efficiently clears the portal circulation of bile salts and the apical Bile Salt Export Pump (BSEP; gene ABCB11) pumps the bile salts out of the hepatocyte into primary bile, against a very steep concentration gradient. Recently, individuals lacking either functional NTCP or OST have been described, completing the quartet of bile acid transport deficiencies as ASBT and BSEP deficiencies were already known for years. Novel (patho)physiological insights have been obtained from knockout mice lacking functional expression of these genes and from pharmacological transporter inhibition in mice or humans. CONCLUSION: Here, we provide a concise overview of the 4 main bile salt transport pathways and of their status as possible target of interventions in cholestatic or metabolic disorders.
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http://dx.doi.org/10.1002/hep.31651DOI Listing
November 2020

Fruticuline A, a chemically-defined diterpene, exerts antineoplastic effects in vitro and in vivo by multiple mechanisms.

Sci Rep 2020 10 5;10(1):16477. Epub 2020 Oct 5.

Department of Pharmacology, Biological Sciences Sector, Federal University of Parana - UFPR, PO Box 19031, Curitiba, PR, 81531-980, Brazil.

Natural products have been recognized as important bioactive compounds on the basis of their wide biological properties. Here we investigated the antitumor effect and molecular mechanisms of the diterpene Fruticuline A (fruti) from Salvia lachnostachys, in human cancer cell lineages and Solid Ehrlich Carcinoma in mice. Fruti reduced MCF-7 and HepG2 proliferation by the reduction of Cyclin D1 levels and decreased NF-κB gene levels in both cell types. Furthermore, fruti also induced apoptosis in HepG2 cells, reduced Bcl-2 gene expression and induced necroptosis by increasing Ripk in MCF-7 cells. In mice, fruti prevented tumor development and reduced Cyclin D1, Bcl-2 and Rela gene levels, and reduced the p-NF-κB/NF-κB ratio in tumor tissue. Furthermore, fruti induced necrosis and apoptosis, increased N-acetyl-β-D-glucosaminidase and TNF-α levels and reduced IL-10 and Vegf levels in tumor tissue. Collectively, fruti exerts antitumor effects through the inhibition of the NF-κB pathway, reducing Cyclin D1 and Bcl-2 levels. In vitro the apoptosis and necroptosis pathways are involved in the cellular death, whereas in vivo, cells undergo necrosis by increased tumor inflammation and reduction of angiogenesis. Thus, fruticuline A acts in tumor cells by multiple mechanisms and represents a promising molecule for drug development in cancer treatment.
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http://dx.doi.org/10.1038/s41598-020-73432-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536426PMC
October 2020

Overexpression of the constitutive androstane receptor and shaken 3D-culturing increase biotransformation and oxidative phosphorylation and sensitivity to mitochondrial amiodarone toxicity of HepaRG cells.

Toxicol Appl Pharmacol 2020 07 16;399:115055. Epub 2020 May 16.

Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, AG&M, Meibergdreef 69-71, 1105 BK, Amsterdam, the Netherlands. Electronic address:

The liver cell line HepaRG is one of the preferred sources of human hepatocytes for in vitro applications. However, mitochondrial energy metabolism is relatively low, which affects hepatic functionality and sensitivity to hepatotoxins. Culturing in a bioartificial liver (BAL) system with high oxygen, medium perfusion, low substrate stiffness, and 3D conformation increases HepaRG functionality and mitochondrial activity compared to conventional monolayer culturing. In addition, drug metabolism has been improved by overexpression of the constitutive androstane receptor (CAR), a regulator of drug and energy metabolism in the new HepaRG-CAR line. Here, we investigated the effect of BAL culturing on the HepaRG-CAR line by applying a simple and downscaled BAL culture procedure based on shaking 3D cultures, named Bal-in-a-dish (BALIAD). We compared monolayer and BALIAD cultures of HepaRG and HepaRG-CAR cells. CAR overexpression and BALIAD culturing synergistically or additively increased transcript levels of CAR and three of the seven tested CAR target genes in biotransformation. Additionally, Cytochrome P450 3A4 activity was 35-fold increased. The mitochondrial energy metabolism was enhanced; lactate production and glucose consumption switched into lactate elimination and glucose production. BALIAD culturing alone reduced glycogen content and increased oxygen consumption and mitochondrial content. Both CAR overexpression and BALIAD culturing decreased mitochondrial superoxide levels. HepaRG-CAR BALIADs were most sensitive to mitochondrial toxicity induced by the hepatotoxin amiodarone, as indicated by oxygen consumption and mitochondrial superoxide accumulation. These data show that BALIAD culturing of HepaRG-CAR cells induces high mitochondrial energy metabolism and xenobiotic metabolism, increasing its potential for drug toxicity studies.
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http://dx.doi.org/10.1016/j.taap.2020.115055DOI Listing
July 2020

Reply.

Hepatology 2020 Nov 16;72(5):1885-1886. Epub 2020 Oct 16.

Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.

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http://dx.doi.org/10.1002/hep.31291DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7702153PMC
November 2020

Inhibition of Hepatic Bile Acid Uptake by Myrcludex B Promotes Glucagon-Like Peptide-1 Release and Reduces Obesity.

Cell Mol Gastroenterol Hepatol 2020 21;10(3):451-466. Epub 2020 Apr 21.

Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands; Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands. Electronic address:

Background & Aims: Bile acids are important metabolic signaling molecules. Bile acid receptor activation promotes body weight loss and improves glycemic control. The incretin hormone GLP-1 and thyroid hormone activation of T4 to T3 have been suggested as important contributors. Here, we identify the hepatic bile acid uptake transporter Na taurocholate co-transporting polypeptide (NTCP) as target to prolong postprandial bile acid signaling.

Methods: Organic anion transporting polypeptide (OATP)1a/1b KO mice with or without reconstitution with human OATP1B1 in the liver were treated with the NTCP inhibitor Myrcludex B for 3.5 weeks after the onset of obesity induced by high fat diet-feeding. Furthermore, radiolabeled T4 was injected to determine the role of NTCP and OATPs in thyroid hormone clearance from plasma.

Results: Inhibition of NTCP by Myrcludex B in obese Oatp1a/1b KO mice inhibited hepatic clearance of bile acids from portal and systemic blood, stimulated GLP-1 secretion, reduced body weight, and decreased (hepatic) adiposity. NTCP inhibition did not affect hepatic T4 uptake nor lead to increased thyroid hormone activation. Myrcludex B treatment increased fecal energy output, explaining body weight reductions amongst unaltered food intake and energy expenditure.

Conclusions: Pharmacologically targeting hepatic bile acid uptake to increase bile acid signaling is a novel approach to treat obesity and induce GLP1- secretion.
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http://dx.doi.org/10.1016/j.jcmgh.2020.04.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363705PMC
April 2020

Genome-wide expression profiling reveals increased stability and mitochondrial energy metabolism of the human liver cell line HepaRG-CAR.

Cytotechnology 2020 Jun 4;72(3):377-395. Epub 2020 Mar 4.

Tytgat Institute for Liver and Intestinal Research, AG&M, Amsterdam UMC, University of Amsterdam, Meibergdreef 69-71, 1105 BK, Amsterdam, The Netherlands.

Human liver cell line HepaRG is a well-known source of human hepatocyte-like cells which, however, displays limited biotransformation and a tendency to transform after 20 passages. The new HepaRG-CAR cell line overexpressing constitutive androstane receptor (CAR, NR1I3), a regulator of detoxification and energy metabolism outperforms the parental HepaRG cell line in various liver functions. To further characterize this cell line and assess its stability we compared HepaRG-CAR with HepaRG cells at different passages for their expression profile, ammonia and lactate metabolism, bile acid and reactive oxygen species (ROS) production. Transcriptomic profiling of HepaRG-CAR vs. HepaRG early-passage revealed downregulation of hypoxia, glycolysis and proliferation and upregulation of oxidative phosphorylation genesets. In addition CAR overexpression downregulated the mTORC1 signaling pathway, which, as mediator of proliferation and metabolic reprogramming, may play an important role in the establishment of the HepaRG-CAR phenotype. The ammonia and lactate metabolism and bile acid production of HepaRG-CAR cells was stable for 10 additional passages compared to HepaRG cells. Interestingly, bile acid production was 4.5-fold higher in HepaRG-CAR vs. HepaRG cells, whereas lactate and ROS production were 2.7- and 2.0-fold lower, respectively. Principal component analysis showed clustering of HepaRG-CAR (early- and late-passage) and HepaRG early-passage and not with HepaRG late-passage indicating that passaging exerted larger effect on the transcriptional profile of HepaRG than HepaRG-CAR cells. In conclusion, overexpression of CAR in HepaRG cells improves their bile acid production, mitochondrial energy metabolism, and stability, with the latter possibly due to reduced ROS production, resulting in an optimized source of human hepatocytes.
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http://dx.doi.org/10.1007/s10616-020-00384-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7225227PMC
June 2020

Miltefosine treatment reduces visceral hypersensitivity in a rat model for irritable bowel syndrome via multiple mechanisms.

Sci Rep 2019 08 29;9(1):12530. Epub 2019 Aug 29.

Tytgat Institute for Liver and Intestinal Research, Amsterdam UMC, Location AMC, Amsterdam, The Netherlands.

Irritable bowel syndrome (IBS) is a heterogenic, functional gastrointestinal disorder of the gut-brain axis characterized by altered bowel habit and abdominal pain. Preclinical and clinical results suggested that, in part of these patients, pain may result from fungal induced release of mast cell derived histamine, subsequent activation of sensory afferent expressed histamine-1 receptors and related sensitization of the nociceptive transient reporter potential channel V1 (TRPV1)-ion channel. TRPV1 gating properties are regulated in lipid rafts. Miltefosine, an approved drug for the treatment of visceral Leishmaniasis, has fungicidal effects and is a known lipid raft modulator. We anticipated that miltefosine may act on different mechanistic levels of fungal-induced abdominal pain and may be repurposed to IBS. In the IBS-like rat model of maternal separation we assessed the visceromotor response to colonic distension as indirect readout for abdominal pain. Miltefosine reversed post-stress hypersensitivity to distension (i.e. visceral hypersensitivity) and this was associated with differences in the fungal microbiome (i.e. mycobiome). In vitro investigations confirmed fungicidal effects of miltefosine. In addition, miltefosine reduced the effect of TRPV1 activation in TRPV1-transfected cells and prevented TRPV1-dependent visceral hypersensitivity induced by intracolonic-capsaicin in rat. Miltefosine may be an attractive drug to treat abdominal pain in IBS.
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http://dx.doi.org/10.1038/s41598-019-49096-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6715706PMC
August 2019

Glyco-conjugated bile acids drive the initial metaplastic gland formation from multi-layered glands through crypt-fission in a murine model.

PLoS One 2019 26;14(7):e0220050. Epub 2019 Jul 26.

Center for Experimental and Molecular Medicine (CEMM), Academic Medical Center, Amsterdam, The Netherlands.

Bile acid reflux is known to be associated with the development of Barrett's esophagus and esophageal adenocarcinoma (EAC), yet the role of specific bile acids and the mechanism behind the metaplastic changes is unclear. Here, we demonstrate that multi-layered glandular structures at the squamo-columnar junction in mice contain multiple cell lineages, which resemble the human esophageal submucosal gland ducts. Exposing mice to patient's refluxates induced expansion of multi-layered glandular structures and development of columnar metaplasia at the squamo-columnar junction. The glycine conjugated bile acids induced an intestinal type of metaplasia more typical for Barrett's esophagus. Through lineage tracing, we excluded the involvement of K5+, DCLK1+, and LGR5+ progenitor cells as the primary source in the development of the glandular metaplastic epithelium. We show that the mechanism behind development of metaplasia involves crypt fission and may be independent of stem cell proliferation. Our findings support the hypothesis that in humans, BE arises from non-squamous cells residing in submucosal gland ducts and that induction of intestinal type of metaplasia is most effectively induced by glycine-conjugated bile acids. These novel insights may lead to more effective strategies to prevent development of Barrett's esophagus and esophageal adenocarcinoma.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0220050PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6660124PMC
February 2020

Autotaxin activity predicts transplant-free survival in primary sclerosing cholangitis.

Sci Rep 2019 06 11;9(1):8450. Epub 2019 Jun 11.

Norwegian PSC Research Center, Department of transplantation medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway.

Autotaxin has been associated with liver disease severity and transplant-free survival. This study aimed to validate autotaxin as a biomarker in two cohorts of Norwegian large-duct PSC patients, one discovery panel (n = 165) and one validation panel (n = 87). Serum activity of autotaxin was measured in diluted sera by a fluorometric enzymatic assay. Patients reaching an end-point, liver transplantation or death, (discovery panel: n = 118 [71.5%]; validation panel: n = 35 [40.2%]), showed higher autotaxin activity compared with the other patients, P < 0.001 and P = 0.004, respectively. Kaplan-Meier survival analyses showed a strong association between increasing autotaxin activity and shorter liver transplant-free survival (discovery panel: P < 0.001, validation panel: P = 0.001). There was no relationship between autotaxin activity and the presence of inflammatory bowel disease or occurrence of hepatobiliary malignancy. In a multivariable analysis, high autotaxin activity was associated with an increased risk of liver transplantation or death (hazard ratio 2.03 (95% confidence interval 1.21-3.40), P < 0.01), independent from Mayo risk score, an in-house enhanced liver fibrosis score and interleukin-8 in serum. In conclusion, increased serum autotaxin activity is associated with reduced liver transplant-free survival independent from Mayo risk score and markers of inflammation and fibrosis.
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http://dx.doi.org/10.1038/s41598-019-44762-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6559994PMC
June 2019

Blocking Sodium-Taurocholate Cotransporting Polypeptide Stimulates Biliary Cholesterol and Phospholipid Secretion in Mice.

Hepatology 2020 01 13;71(1):247-258. Epub 2019 Aug 13.

Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.

Active secretion of bile salts into the canalicular lumen drives bile formation and promotes biliary cholesterol and phospholipid output. Disrupting hepatic bile salt uptake, by inhibition of sodium-taurocholate cotransporting polypetide (NTCP; Slc10a1) with Myrcludex B, is expected to limit bile salt flux through the liver and thereby to decrease biliary lipid excretion. Here, we show that Myrcludex B-mediated NTCP inhibition actually causes an increase in biliary cholesterol and phospholipid excretion whereas biliary bile salt output and bile salt composition remains unchanged. Increased lysosomal discharge into bile was excluded as a potential contributor to increased biliary lipid secretion. Induction of cholesterol secretion was not a consequence of increased ATP-binding cassette subfamily G member 5/8 activity given that NTCP inhibition still promoted cholesterol excretion in Abcg8 mice. Stimulatory effects of NTCP inhibition were maintained in Sr-b1 mice, eliminating the possibility that the increase in biliary lipids was derived from enhanced uptake of high-density lipoprotein-derived lipids. NTCP inhibition shifts bile salt uptake, which is generally more periportally restricted, toward pericentral hepatocytes, as was visualized using a fluorescently labeled conjugated bile salt. As a consequence, exposure of the canalicular membrane to bile salts was increased, allowing for more cholesterol and phospholipid molecules to be excreted per bile salt. Conclusion: NTCP inhibition increases biliary lipid secretion, which is independent of alterations in bile salt output, biliary bile salt hydrophobicity, or increased activity of dedicated cholesterol and phospholipid transporters. Instead, NTCP inhibition shifts hepatic bile salt uptake from mainly periportal hepatocytes toward pericentral hepatocytes, thereby increasing exposure of the canalicular membrane to bile salts linking to increased biliary cholesterol secretion. This process provides an additional level of control to biliary cholesterol and phospholipid secretion.
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http://dx.doi.org/10.1002/hep.30792DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7003915PMC
January 2020

Liver-directed gene therapy results in long-term correction of progressive familial intrahepatic cholestasis type 3 in mice.

J Hepatol 2019 07 29;71(1):153-162. Epub 2019 Mar 29.

Amsterdam University Medical Centers, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology and Metabolism, Meibergdreef 9, Amsterdam, The Netherlands. Electronic address:

Background & Aims: Progressive familial intrahepatic cholestasis type 3 (PFIC3), for which there are limited therapeutic options, often leads to end-stage liver disease before adulthood due to impaired ABCB4-dependent phospholipid transport to bile. Using adeno-associated virus serotype 8 (AAV8)-mediated gene therapy, we aimed to restore the phospholipid content in bile to levels that prevent liver damage, thereby enabling stable hepatic ABCB4 expression and long-term correction of the phenotype in a murine model of PFIC3.

Methods: Ten-week-old Abcb4 mice received a single dose of AAV8-hABCB4 (n = 10) or AAV8-GFP (n = 7) under control of a liver specific promoter via tail vein injection. Animals were sacrificed either 10 or 26 weeks after vector administration to assess transgene persistence, after being challenged with a 0.1% cholate diet for 2 weeks. Periodic evaluation of plasma cholestatic markers was performed and bile duct cannulation enabled analysis of biliary phospholipids. Liver fibrosis and the Ki67 proliferation index were assessed by immunohistochemistry.

Results: Stable transgene expression was achieved in all animals that received AAV8-hABCB4 up to 26 weeks after administration. AAV8-hABCB4 expression restored biliary phospholipid excretion, increasing the phospholipid and cholesterol content in bile to levels that ameliorate liver damage. This resulted in normalization of the plasma cholestatic markers, alkaline phosphatase and bilirubin. In addition, AAV8-hABCB4 prevented progressive liver fibrosis and reduced hepatocyte proliferation for the duration of the study.

Conclusion: Liver-directed gene therapy provides stable hepatic ABCB4 expression and long-term correction of the phenotype in a murine model of PFIC3. Translational studies that verify the clinical feasibility of this approach are warranted.

Lay Summary: Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a severe genetic liver disease that results from impaired transport of lipids to bile, which makes the bile toxic to liver cells. Because therapeutic options are currently limited, this study aims to evaluate gene therapy to correct the underlying genetic defect in a mouse model of this disease. By introducing a functional copy of the missing gene in liver cells of mice, we were able to restore lipid transport to bile and strongly reduce damage to the liver. The proliferation of liver cells was also reduced, which contributes to long-term correction of the phenotype. Further studies are required to evaluate whether this approach can be applied to patients with PFIC3.
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http://dx.doi.org/10.1016/j.jhep.2019.03.021DOI Listing
July 2019

Overexpression of carbamoyl-phosphate synthase 1 significantly improves ureagenesis of human liver HepaRG cells only when cultured under shaking conditions.

Mitochondrion 2019 07 22;47:298-308. Epub 2019 Feb 22.

Amsterdam UMC, University of Amsterdam, Tytgat Institute for Liver and Intestinal Research, AG&M, Meibergdreef 69-71, 1105 BK Amsterdam, The Netherlands; Amsterdam UMC, University of Amsterdam, Surgical Laboratory, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Electronic address:

Hyperammonemia is an important contributing factor to hepatic encephalopathy in end-stage liver failure patients. Therefore reducing hyperammonemia is a requisite of bioartificial liver support (BAL). Ammonia elimination by human liver HepaRG cells occurs predominantly through reversible fixation into amino acids, whereas the irreversible conversion into urea is limited. Compared to human liver, the expression and activity of the three urea cycle (UC) enzymes carbamoyl-phosphate synthase1 (CPS1), ornithine transcarbamoylase (OTC) and arginase1, are low. To improve HepaRG cells as BAL biocomponent, its rate limiting factor of the UC was determined under two culture conditions: static and dynamic medium flow (DMF) achieved by shaking. HepaRG cells increasingly converted escalating arginine doses into urea, indicating that arginase activity is not limiting ureagenesis. Neither was OTC activity, as a stable HepaRG line overexpressing OTC exhibited a 90- and 15.7-fold upregulation of OTC transcript and activity levels, without improvement in ureagenesis. However, a stable HepaRG line overexpressing CPS1 showed increased mitochondrial stress and reduced hepatic differentiation without promotion of the CPS1 transcript level or ureagenesis under static-culturing conditions, yet, it exhibited a 4.3-fold increased ureagenesis under DMF. This was associated with increased CPS1 transcript and activity levels amounting to >2-fold, increased mitochondrial abundance and hepatic differentiation. Unexpectedly, the transcript levels of several other UC genes increased up to 6.8-fold. We conclude that ureagenesis can be improved in HepaRG cells by CPS1 overexpression, however, only in combination with DMF-culturing, suggesting that both the low CPS1 level and static-culturing, possibly due to insufficient mitochondria, are limiting UC.
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http://dx.doi.org/10.1016/j.mito.2019.02.005DOI Listing
July 2019

HepaRG-Progenitor Cell Derived Hepatocytes Cultured in Bioartificial Livers Are Protected from Healthy- and Acute Liver Failure-Plasma Induced Toxicity.

Cell Physiol Biochem 2018 15;48(5):2189-2204. Epub 2018 Aug 15.

Tytgat Institute for Liver and Intestinal Research, Academic Medical Center (AMC), Amsterdam, the Netherlands.

Background/aims: For applicability of cell-based therapies aimed at the treatment of liver failure, such as bioartificial livers (BALs) and hepatocyte transplantation, it is essential that the applied hepatocytes tolerate exposure to the patient plasma. However, plasma from both healthy donors and acute liver failure (ALF) patients is detrimental to hepatocytes and hepatic cell lines, such as HepaRG. We aimed to elucidate the underlying mechanisms of plasma-induced toxicity against HepaRG cells in order to ultimately develop methods to reduce this toxicity and render HepaRG-BAL treatment more effective.

Methods: Differentiated HepaRG cells cultured in monolayers and laboratory-scale BALs were exposed to culture medium, healthy human plasma, healthy porcine plasma and ALF porcine plasma. Healthy human plasma was fractionated based on size- and polarity, albumin depleted and heat treated to characterize the toxic fraction. The cells were assessed for viability by total protein content and trypan blue staining. Their hepatic differentiation was assessed on transcript level through qRT-PCR and microarray analysis, and on functional level for Cytochrome P450 3A4 activity and ammonia elimination. Mitochondrial damage was assessed by JC-1 staining and mitochondrial gene transcription.

Results: Sixteen hours of healthy human plasma exposure did not affect viability, however, hepatic gene-transcript levels decreased dramatically and dose-dependently within four hours of exposure. These changes were associated with early NF-kB signaling and a shift from mitochondrial energy metabolism towards glycolysis. Healthy human plasma-toxicity was associated with the dose-dependent presence of heat-resistant, albumin-bound and (partly) hydrophobic toxic compound(s). HepaRG cells cultured in BALs were partially protected from plasma-toxicity, which was mainly attributable to medium perfusion and/or 3D configuration applied during BAL culturing. The detrimental human plasma effects were reversible in BAL-cultured cells. Porcine ALF-plasma elicited mitotoxicity additional to the basal detrimental effect of porcine healthy plasma, which were only partially reversible.

Conclusion: A specific fraction of human plasma reduces hepatic differentiation of HepaRG cultures, in association with early NF-κB activation. In addition, ALF-plasma elicits mitotoxic effects. These findings allow for a targeted approach in preventing plasma-induced cell damage.
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http://dx.doi.org/10.1159/000492560DOI Listing
September 2018

Role of the placenta in serum autotaxin elevation during maternal cholestasis.

Am J Physiol Gastrointest Liver Physiol 2018 09 21;315(3):G399-G407. Epub 2018 Jun 21.

Experimental Hepatology and Drug Targeting (HEVEFARM), IBSAL, University of Salamanca , Salamanca , Spain.

Intrahepatic cholestasis of pregnancy (ICP) is frequently accompanied by pruritus, whose etiology has been associated with an enhanced production of lysophosphatidic acid (LPA) by the combined action of phospholipase A1/A2 (PLA1/PLA2) and autotaxin (ATX). Here, we have investigated whether the placenta is involved in LPA release to maternal circulation during ICP. Serum levels of ATX and LPA (determined by ELISA) were elevated in women with ICP, and a correlation between both parameters was found. No relationship between serum levels of ATX or LPA and bile acids was found. Expression levels of ATX and PLA2 were determined by RT-qPCR and Western blot. Placenta ATX but not PLA2 was significantly upregulated in ICP, and a tendency to increase was found at the protein level. A correlation between serum ATX and placental ATX mRNA levels was found. In human placenta at term, ATX was clearly detected (by immunofluorescence) in Hofbauer cells, but only faintly in trophoblast cells. In pregnant rats, the expression of Atx and Pla2 in placenta was lower than in liver. When obstructive cholestasis was imposed by bile duct ligation from day 14 of gestation until term, placenta Atx and Pla2 expression was markedly enhanced, and overexpression was confirmed at the protein level for Pla2, whereas Atx protein was not detected. In conclusion, the placenta substantially participates in LPA production during gestation. This contribution is markedly higher during maternal cholestasis and hence, may be involved in ICP-associated pruritus. NEW & NOTEWORTHY Fetal placental macrophages and, to a lesser extent, trophoblast cells express high levels of autotaxin at term. An increased expression of mRNA and protein autotaxin, the key secretory enzyme responsible for the production of lysophosphatidic acid in serum, has been observed in placentas of women with cholestasis of pregnancy, which supports that the placenta can contribute to an increased production of this pruritogenic compound in women suffering from this liver disease.
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http://dx.doi.org/10.1152/ajpgi.00112.2018DOI Listing
September 2018

Intestinal Farnesoid X Receptor Activation by Pharmacologic Inhibition of the Organic Solute Transporter α-β.

Cell Mol Gastroenterol Hepatol 2018 Mar 28;5(3):223-237. Epub 2017 Nov 28.

Tytgat Institute for Liver and Intestinal Research, Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology and Metabolism, Academic Medical Center, Amsterdam, The Netherlands.

Background & Aims: The organic solute transporter α-β (OSTα-OSTβ) mainly facilitates transport of bile acids across the basolateral membrane of ileal enterocytes. Therefore, inhibition of OSTα-OSTβ might have similar beneficial metabolic effects as intestine-specific agonists of the major nuclear receptor for bile acids, the farnesoid X receptor (FXR). However, no OSTα-OSTβ inhibitors have yet been identified.

Methods: Here, we developed a screen to identify specific inhibitors of OSTα-OSTβ using a genetically encoded Förster Resonance Energy Transfer (FRET)-bile acid sensor that enables rapid visualization of bile acid efflux in living cells.

Results: As proof of concept, we screened 1280 Food and Drug Administration-approved drugs of the Prestwick chemical library. Clofazimine was the most specific hit for OSTα-OSTβ and reduced transcellular transport of taurocholate across Madin-Darby canine kidney epithelial cell monolayers expressing apical sodium bile acid transporter and OSTα-OSTβ in a dose-dependent manner. Moreover, pharmacologic inhibition of OSTα-OSTβ also moderately increased intracellular taurocholate levels and increased activation of intestinal FXR target genes. Oral administration of clofazimine in mice (transiently) increased intestinal FXR target gene expression, confirming OSTα-OSTβ inhibition in vivo.

Conclusions: This study identifies clofazimine as an inhibitor of OSTα-OSTβ in vitro and in vivo, validates OSTα-OSTβ as a drug target to enhance intestinal bile acid signaling, and confirmed the applicability of the Förster Resonance Energy Transfer-bile acid sensor to screen for inhibitors of bile acid efflux pathways.
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http://dx.doi.org/10.1016/j.jcmgh.2017.11.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5904037PMC
March 2018

A practice-changing culture method relying on shaking substantially increases mitochondrial energy metabolism and functionality of human liver cell lines.

PLoS One 2018 19;13(4):e0193664. Epub 2018 Apr 19.

Tytgat Institute for Liver and Intestinal Research, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, The Netherlands.

Practice-changing culturing techniques of hepatocytes are highly required to increase their differentiation. Previously, we found that human liver cell lines HepaRG and C3A acquire higher functionality and increased mitochondrial biogenesis when cultured in the AMC-Bioartificial liver (BAL). Dynamic medium flow (DMF) is one of the major contributors to this stimulatory effect. Recently, we found that DMF-culturing by shaking of HepaRG monolayers resulted in higher mitochondrial biogenesis. Here we further investigated the effect of DMF-culturing on energy metabolism and hepatic functionality of HepaRG and C3A monolayers. HepaRG and C3A DMF-monolayers were incubated with orbital shaking at 60 rpm during the differentiation phase, while control monolayers were maintained statically. Subsequently, energy metabolism and hepatic functionality were compared between static and DMF-cultures. DMF-culturing of HepaRG cells substantially increased hepatic differentiation; transcript levels of hepatic structural genes and hepatic transcription regulators were increased up to 15-fold (Cytochrome P450 3A4) and nuclear translocation of hepatic transcription factor CEBPα was stimulated. Accordingly, hepatic functions were positively affected, including ammonia elimination, urea production, bile acid production, and CYP3A4 activity. DMF-culturing shifted energy metabolism from aerobic glycolysis towards oxidative phosphorylation, as indicated by a decline in lactate production and glucose consumption, and an increase in oxygen consumption. Similarly, DMF-culturing increased mitochondrial energy metabolism and hepatic functionality of C3A cells. In conclusion, simple shaking of monolayer cultures substantially improves mitochondrial energy metabolism and hepatic differentiation of human liver cell lines. This practice-changing culture method may prove to prolong the in-vitro maintenance of primary hepatocytes and increase hepatic differentiation of stem cells.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0193664PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5908182PMC
July 2018

Na -taurocholate cotransporting polypeptide inhibition has hepatoprotective effects in cholestasis in mice.

Hepatology 2018 09 27;68(3):1057-1069. Epub 2018 Apr 27.

Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology & Hepatology, Amsterdam Gastroenterology and Metabolism, AMC, Amsterdam, the Netherlands.

Accumulation of bile salts (BSs) during cholestasis leads to hepatic and biliary injury, driving inflammatory and fibrotic processes. The Na -Taurocholate Cotransporting Polypeptide (NTCP) is the major hepatic uptake transporter of BSs, and can be specifically inhibited by myrcludex B. We hypothesized that inhibition of NTCP dampens cholestatic liver injury. Acute cholestasis was induced in mice by a 3.5-diethoxycarbonyl-1.4-dihydrocollidine (DDC) diet or by bile duct ligation (BDL). Chronic cholestasis was investigated in Atp8b1-G308V and Abcb4/Mdr2 deficient mice. Mice were injected daily with myrcludex B or vehicle. Myrcludex B reduced plasma alkaline phosphatase (ALP) levels in DDC-fed, Atp8b1-G308V and BDL mice by 39%, 27% and 48% respectively. Expression of genes involved in fibrosis, proliferation and inflammation was reduced by myrcludex B treatment in DDC-fed and Atp8b1-G308V mice. NTCP-inhibition increased plasma BS levels from 604±277 to 1746±719 μm in DDC-fed mice, 432±280 to 762±288 μm in Atp8b1-G308V mice and from 522±130 to 3625±378 μm in BDL mice. NTCP-inhibition strongly aggravated weight loss in BDL mice, but not in other cholestatic models studied. NTCP-inhibition reduced biliary BS output in DDC-fed and Atp8b1-G308V mice by ∼50% while phospholipid (PL) output was maintained, resulting in a higher PL/BS ratio. Conversely, liver injury in Abcb4 deficient mice, lacking biliary phospholipid output, was aggravated after myrcludex B treatment. Conclusion: NTCP-inhibition by myrcludex B has hepatoprotective effects, by reducing BS load in hepatocytes and increasing the biliary PL/BS ratio. High micromolar plasma BS levels after NTCP-inhibition were well tolerated. NTCP-inhibition may be beneficial in selected forms of cholestasis. (Hepatology 2018).
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http://dx.doi.org/10.1002/hep.29888DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6175374PMC
September 2018

Improved oxygenation dramatically alters metabolism and gene expression in cultured primary mouse hepatocytes.

Hepatol Commun 2018 03 9;2(3):299-312. Epub 2018 Feb 9.

Tytgat Institute for Liver and Intestinal Research, Academic Medical Center University of Amsterdam Amsterdam the Netherlands.

Primary hepatocyte culture is an important system for the study of liver functions. , hepatocytes have high oxidative metabolism. However, oxygen supply by means of diffusion in static cultures is much less than that by blood circulation . Therefore, we investigated whether hypoxia contributes to dedifferentiation and deregulated metabolism in cultured hepatocytes. To this end, murine hepatocytes were cultured under static or shaken (60 revolutions per minute) conditions in a collagen sandwich. The effect of hypoxia on hepatocyte cultures was examined by metabolites in media and cells, hypoxia-inducible factors (HIF)-1/2α western blotting, and real-time quantitative polymerase chain reaction for HIF target genes and key genes of glucose and lipid metabolism. Hepatocytes in shaken cultures showed lower glycolytic activity and triglyceride accumulation than static cultures, compatible with improved oxygen delivery and mitochondrial energy metabolism. Consistently, static cultures displayed significant HIF-2α expression, which was undetectable in freshly isolated hepatocytes and shaken cultures. Transcript levels of HIF target genes (glyceraldehyde 3-phosphate dehydrogenase [], glucose transporter 1 [], pyruvate dehydrogenase kinase 1 [], and lactate dehydrogenase A []) and key genes of lipid metabolism, such as carnitine palmitoyltransferase 1 (), apolipoprotein B (), and acetyl-coenzyme A carboxylase 1 (), were significantly lower in shaken compared to static cultures. Moreover, expression of hepatocyte nuclear factor 4α () and farnesoid X receptor () were better preserved in shaken cultures as a result of improved oxygen delivery. We further revealed that HIF-2 signaling was involved in hypoxia-induced down-regulation of . : Primary murine hepatocytes in static culture suffer from hypoxia. Improving oxygenation by simple shaking prevents major changes in expression of metabolic enzymes and aberrant triglyceride accumulation; in addition, it better maintains the differentiation state of the cells. The shaken culture is, therefore, an advisable strategy for the use of primary hepatocytes as an model. ( 2018;2:299-312).
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http://dx.doi.org/10.1002/hep4.1140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5831026PMC
March 2018

Oxygen drives hepatocyte differentiation and phenotype stability in liver cell lines.

J Cell Commun Signal 2018 Sep 4;12(3):575-588. Epub 2018 Feb 4.

Tytgat Institute for Liver and Intestinal Research, Academic Medical Center (AMC), Meibergdreef 69-71, 1105BK, Amsterdam, The Netherlands.

The in vitro generation of terminally differentiated hepatocytes is an unmet need. We investigated the contribution of oxygen concentration to differentiation in human liver cell lines HepaRG and C3A. HepaRG cells were cultured under hypoxia (5%O), normoxia (21%O) or hyperoxia (40%O). Cultures were analysed for hepatic functions, gene transcript levels, and protein expression of albumin, hepatic transcription factor CEBPα, hepatic progenitor marker SOX9, and hypoxia inducible factor (HIF)1α. C3A cells were analysed after exposure to normoxia or hyperoxia. In hyperoxic HepaRG cultures, urea cycle activity, bile acid synthesis, CytochromeP450 3A4 (CYP3A4) activity and ammonia elimination were 165-266% increased. These effects were reproduced in C3A cells. Whole transcriptome analysis of HepaRG cells revealed that 240 (of 23.223) probes were differentially expressed under hyperoxia, with an overrepresentation of genes involved in hepatic differentiation, metabolism and extracellular signalling. Under hypoxia, CYP3A4 activity and ammonia elimination were inhibited almost completely and 5/5 tested hepatic genes and 2/3 tested hepatic transcription factor genes were downregulated. Protein expression of SOX9 and HIF1α was strongly positive in hypoxic cultures, variable in normoxic cultures and predominantly negative in hyperoxic cultures. Conversely, albumin and CEBPα expression were highest in hyperoxic cultures. HepaRG cells that were serially passaged under hypoxia maintained their capacity to differentiate under normoxia, in contrast to cells passaged under normoxia. Hyperoxia increases hepatocyte differentiation in HepaRG and C3A cells. In contrast, hypoxia maintains stem cell characteristics and inhibits hepatic differentiation of HepaRG cells, possibly through the activity of HIF1α.
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http://dx.doi.org/10.1007/s12079-018-0456-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039343PMC
September 2018

Reduced hepatitis B and D viral entry using clinically applied drugs as novel inhibitors of the bile acid transporter NTCP.

Sci Rep 2017 11 10;7(1):15307. Epub 2017 Nov 10.

Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology and Metabolism, AMC, Amsterdam, The Netherlands.

The sodium taurocholate co-transporting polypeptide (NTCP, SLC10A1) is the main hepatic transporter of conjugated bile acids, and the entry receptor for hepatitis B virus (HBV) and hepatitis delta virus (HDV). Myrcludex B, a synthetic peptide mimicking the NTCP-binding domain of HBV, effectively blocks HBV and HDV infection. In addition, Myrcludex B inhibits NTCP-mediated bile acid uptake, suggesting that also other NTCP inhibitors could potentially be a novel treatment of HBV/HDV infection. This study aims to identify clinically-applied compounds intervening with NTCP-mediated bile acid transport and HBV/HDV infection. 1280 FDA/EMA-approved drugs were screened to identify compounds that reduce uptake of taurocholic acid and lower Myrcludex B-binding in U2OS cells stably expressing human NTCP. HBV/HDV viral entry inhibition was studied in HepaRG cells. The four most potent inhibitors of human NTCP were rosiglitazone (IC 5.1 µM), zafirlukast (IC 6.5 µM), TRIAC (IC 6.9 µM), and sulfasalazine (IC 9.6 µM). Chicago sky blue 6B (IC 7.1 µM) inhibited both NTCP and ASBT, a distinct though related bile acid transporter. Rosiglitazone, zafirlukast, TRIAC, sulfasalazine, and chicago sky blue 6B reduced HBV/HDV infection in HepaRG cells in a dose-dependent manner. Five out of 1280 clinically approved drugs were identified that inhibit NTCP-mediated bile acid uptake and HBV/HDV infection in vitro.
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http://dx.doi.org/10.1038/s41598-017-15338-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5681660PMC
November 2017

Role of the bicarbonate-responsive soluble adenylyl cyclase in cholangiocyte apoptosis in primary biliary cholangitis; a new hypothesis.

Biochim Biophys Acta Mol Basis Dis 2018 04 28;1864(4 Pt B):1232-1239. Epub 2017 Sep 28.

Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, The Netherlands. Electronic address:

Primary biliary cholangitis (PBC) is a chronic fibrosing cholangiopathy characterized by an autoimmune stereotype and defective biliary bicarbonate secretion due to down-regulation of anion exchanger 2 (AE2). Despite the autoimmune features, immunosuppressants are ineffective while two bile acid-based therapies (ursodeoxycholic acid and obeticholic acid) have been shown to improve biochemical and histological features of cholestasis and long-term prognosis. However, the etiology and pathogenesis of PBC is largely unknown. Recently, it has been shown that microRNA-506 (miR-506) on chromosome X is up-regulated in PBC cholangiocytes and suppresses AE2 expression, which sensitizes cholangiocytes to bile salt-induced apoptosis by activating soluble adenylyl cyclase (sAC), an evolutionarily conserved bicarbonate sensor. In this review, we discuss the experimental evidence for the emerging role of the miR-506-AE2-sAC axis in PBC pathogenesis. We further hypothesize that the initial disease trigger induces an X-linked epigenetic change, leading to a female-biased activation of the miR-506-AE2-sAC axis. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni and Peter Jansen.
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http://dx.doi.org/10.1016/j.bbadis.2017.09.022DOI Listing
April 2018

MicroRNA-506 promotes primary biliary cholangitis-like features in cholangiocytes and immune activation.

Hepatology 2018 04 21;67(4):1420-1440. Epub 2018 Feb 21.

Department of Liver and Gastrointestinal Diseases, Biodonostia Research Institute-Donostia University Hospital, University of the Basque Country (UPV/EHU), San Sebastian, Spain.

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease associated with autoimmune phenomena targeting intrahepatic bile duct cells (cholangiocytes). Although its etiopathogenesis remains obscure, development of antimitochondrial autoantibodies against pyruvate dehydrogenase complex E2 is a common feature. MicroRNA (miR) dysregulation occurs in liver and immune cells of PBC patients, but its functional relevance is largely unknown. We previously reported that miR-506 is overexpressed in PBC cholangiocytes and directly targets both Cl / HCO3- anion exchanger 2 and type III inositol 1,4,5-trisphosphate receptor, leading to cholestasis. Here, the regulation of miR-506 gene expression and its role in cholangiocyte pathophysiology and immune activation was studied. Several proinflammatory cytokines overexpressed in PBC livers (such as interleukin-8 [IL8], IL12, IL17, IL18, and tumor necrosis factor alpha) stimulated miR-506 promoter activity in human cholangiocytes, as revealed by luciferase reporter assays. Experimental overexpression of miR-506 in cholangiocytes dysregulated the cell proteomic profile (by mass spectrometry), affecting proteins involved in different biological processes including mitochondrial metabolism. In cholangiocytes, miR-506 (1) induced dedifferentiation with down-regulation of biliary and epithelial markers together with up-regulation of mesenchymal, proinflammatory, and profibrotic markers; (2) impaired cell proliferation and adhesion; (3) increased oxidative and endoplasmic reticulum stress; (4) caused DNA damage; and (5) sensitized to caspase-3-dependent apoptosis induced by cytotoxic bile acids. These events were also associated with impaired energy metabolism in mitochondria (proton leak and less adenosine triphosphate production) and pyruvate dehydrogenase complex E2 overexpression. Coculture of miR-506 overexpressing cholangiocytes with PBC immunocytes induced activation and proliferation of PBC immunocytes.

Conclusion: Different proinflammatory cytokines enhance the expression of miR-506 in biliary epithelial cells; miR-506 induces PBC-like features in cholangiocytes and promotes immune activation, representing a potential therapeutic target for PBC patients. (Hepatology 2018;67:1420-1440).
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http://dx.doi.org/10.1002/hep.29533DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857422PMC
April 2018

AMC-Bio-Artificial Liver culturing enhances mitochondrial biogenesis in human liver cell lines: The role of oxygen, medium perfusion and 3D configuration.

Mitochondrion 2018 03 24;39:30-42. Epub 2017 Aug 24.

Tytgat Institute for Liver and Intestinal Research, Academic Medical Center (AMC), University of Amsterdam, Postbus 22660, 1100 DD Amsterdam, The Netherlands; Surgical Laboratory, Academic Medical Center (AMC), University of Amsterdam, Postbus 22660, 1100 DD Amsterdam, The Netherlands. Electronic address:

Background: Human liver cell lines, like HepaRG and C3A, acquire higher functionality when cultured in the AMC-Bio-Artificial Liver (AMC-BAL). The three main differences between BAL and monolayer culture are the oxygenation (40% vs 20%O), dynamic vs absent medium perfusion and 3D vs 2D configuration. Here, we investigated the background of the differences between BAL-cultures and monolayers.

Methods: We performed whole-genome microarray analysis on HepaRG monolayer and BAL-cultures. Next, mitochondrial biogenesis was studied in monolayer and BAL-cultures of HepaRG and C3A. The driving forces for mitochondrial biogenesis by BAL-culturing were investigated in representative culture models differing in oxygenation level, medium flow or 2D vs 3D configuration.

Results: Gene-sets related to mitochondrial energy metabolism were most prominently up-regulated in HepaRG-BAL vs monolayer cultures. This was confirmed by a 2.4-fold higher mitochondrial abundance with increased expression of mitochondrial OxPhos complexes. Moreover, the transcript levels of mitochondria-encoded genes were up to 3.6-fold induced and mitochondrial membrane potential activity was 8.3-fold increased in BAL vs monolayers. Culturing with 40% O, dynamic medium flow and/or in 3D increased the mitochondrial abundance and expression of mitochondrial complexes vs standard monolayer culturing. The stimulatory effect of the BAL culture on mitochondrial biogenesis was confirmed in C3A cells in which mitochondrial abundance increased 2.2-fold with induction of mitochondria-encoded genes.

Conclusions And General Significance: The increased functionality of liver cell lines upon AMC-BAL culturing is associated with increased mitochondrial biogenesis. High oxygenation, medium perfusion and 3D configuration contribute to the up-regulation of the mitochondrial biogenesis.
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http://dx.doi.org/10.1016/j.mito.2017.08.011DOI Listing
March 2018

Annexin A11 is targeted by IgG4 and IgG1 autoantibodies in IgG4-related disease.

Gut 2018 04 1;67(4):728-735. Epub 2017 Aug 1.

Department of Gastroenterology & Hepatology, Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands.

Objective: Immunoglobulin G4-related disease (IgG4-RD) is a multiorgan immune-mediated disease that predominantly affects the biliary tract (IgG4-associated cholangitis, IAC) and pancreas (autoimmune pancreatitis, AIP). We recently identified highly expanded IgG4+ B-cell receptor clones in blood and affected tissues of patients with IAC/AIP suggestive of specific (auto)antigenic stimuli involved in initiating and/or maintaining the inflammatory response. This study aimed to identify (auto)antigen(s) that are responsible for the clonal expansion of IgG4+ B cells in IgG4-RD.

Design: We screened sera of patients with IAC/AIP (n=50), in comparison to control sera of patients with primary sclerosing cholangitis (PSC) and pancreatobiliary malignancies (n=47), for reactivity against human H69 cholangiocyte lysates on immunoblot. Subsequently, target antigens were immunoprecipitated and analysed by mass spectrometry.

Results: Prominent reactivity against a 56 kDa protein was detected in human H69 cholangiocyte lysates exposed to sera of nine patients with IAC/AIP. Affinity purification and mass spectrometry analysis identified annexin A11, a calcium-dependent phospholipid-binding protein. Annexin A11-specific IgG4 and IgG1 antibodies were only detected in serum of patients with IgG4-RD of the biliary tract/pancreas/salivary glands and not in disease mimickers with PSC and pancreatobiliary malignancies. Epitope analysis showed that two annexin A11 epitopes targeted by IgG1 and IgG4 autoantibodies were shared between patients with IAC/AIP and IgG4 antibodies blocked binding of IgG1 antibodies to the shared annexin A11 epitopes.

Conclusion: Our data suggest that IgG1-mediated pro-inflammatory autoreactivity against annexin A11 in patients with IgG4-RD may be attenuated by formation of annexin A11-specific IgG4 antibodies supporting an anti-inflammatory role of IgG4 in IgG4-RD.
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http://dx.doi.org/10.1136/gutjnl-2017-314548DOI Listing
April 2018

Fibrates for the treatment of cholestatic itch (FITCH): study protocol for a randomized controlled trial.

Trials 2017 05 23;18(1):230. Epub 2017 May 23.

Tytgat Institute for Liver and Intestinal Research, Department of Gastroenterology and Hepatology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.

Background: Pruritus (itch) is a frequent, burdensome and difficult-to-treat symptom in patients with cholestasis. Fibrates are currently under investigation for the treatment of primary biliary cholangitis in patients with a suboptimal response to ursodeoxycholic acid. Moreover, there is empirical evidence for a possible antipruritic effect. We aim to prove this in a randomized controlled trial, including patients with cholestatic liver diseases other than primary biliary cholangitis that are accompanied by pruritus.

Methods: A multicenter investigator-initiated, double-blind, randomized placebo-controlled trial to evaluate the effect of bezafibrate on cholestatic pruritus in 84 adult patients with primary biliary cholangitis or primary/secondary sclerosing cholangitis. Primary outcome is the proportion of patients with a reduction of itch intensity of 50% or more (measured on a Visual Analog Scale) after 21 days of treatment with bezafibrate 400 mg qid or placebo. Secondary outcomes include the effect of bezafibrate on a five-dimensional itch score, liver disease-specific quality of life, serum liver tests and autotaxin activity. Safety will be evaluated through serum parameters for kidney function and rhabdomyolysis as well as precise recording of (serious) adverse events. We provide a schematic overview of the study protocol and describe the methods used to recruit and randomize patients, collect and handle data and perform statistical analyses.

Discussion: Given its favorable safety profile and anticholestatic properties, bezafibrate may become the new first-line treatment option for treating cholestatic pruritus.

Trial Registration: Netherlands Trial Register, ID: NCT02701166 . Registered on 2 March 2016; Netherlands Trial Register, ID: NTR5436 . Registered on 3 August 2015.
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http://dx.doi.org/10.1186/s13063-017-1966-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5442649PMC
May 2017

Hepatic uptake of conjugated bile acids is mediated by both sodium taurocholate cotransporting polypeptide and organic anion transporting polypeptides and modulated by intestinal sensing of plasma bile acid levels in mice.

Hepatology 2017 11 29;66(5):1631-1643. Epub 2017 Sep 29.

Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands.

The Na -taurocholate cotransporting polypeptide (NTCP/SLC10A1) is believed to be pivotal for hepatic uptake of conjugated bile acids. However, plasma bile acid levels are normal in a subset of NTCP knockout mice and in mice treated with myrcludex B, a specific NTCP inhibitor. Here, we elucidated which transport proteins mediate the hepatic uptake of conjugated bile acids and demonstrated intestinal sensing of elevated bile acid levels in plasma in mice. Mice or healthy volunteers were treated with myrcludex B. Hepatic bile acid uptake kinetics were determined in wild-type (WT), organic anion transporting polypeptide (OATP) knockout mice (lacking Slco1a/1b isoforms), and human OATP1B1-transgenic mice. Effects of fibroblast growth factor 19 (FGF19) on hepatic transporter mRNA levels were assessed in rat hepatoma cells and in mice by peptide injection or adeno-associated virus-mediated overexpression. NTCP inhibition using myrcludex B had only moderate effects on bile acid kinetics in WT mice, but completely inhibited active transport of conjugated bile acid species in OATP knockout mice. Cholesterol 7α-hydroxylase Cyp7a1 expression was strongly down-regulated upon prolonged inhibition of hepatic uptake of conjugated bile acids. Fgf15 (mouse counterpart of FGF19) expression was induced in hypercholanemic OATP and NTCP knockout mice, as well as in myrcludex B-treated cholestatic mice, whereas plasma FGF19 was not induced in humans treated with myrcludex B. Fgf15/FGF19 expression was induced in polarized human enterocyte-models and mouse organoids by basolateral incubation with a high concentration (1 mM) of conjugated bile acids.

Conclusion: NTCP and OATPs contribute to hepatic uptake of conjugated bile acids in mice, whereas the predominant uptake in humans is NTCP mediated. Enterocytes sense highly elevated levels of (conjugated) bile acids in the systemic circulation to induce FGF15/19, which modulates hepatic bile acid synthesis and uptake. (Hepatology 2017;66:1631-1643).
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http://dx.doi.org/10.1002/hep.29251DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5698707PMC
November 2017