Gene Expression Changes Induced by PPAR Gamma Agonists in Animal and Human Liver

Thiazolidinediones are a class of Peroxisome Proliferator Activated Receptor γ (PPARγ) agonists that reduce insulin resistance in type 2 diabetic patients. Although no detectable hepatic toxicity has been evidenced in animal studies during preclinical trials, these molecules have nevertheless induced hepatic adverse effects in some treated patients. The mechanism(s) of hepatotoxicity remains equivocal. Several studies have been conducted using PCR analysis and microarray technology to identify possible target genes and here we review the data obtained from various in vivo and in vitro experimental models. Although PPARγ is expressed at a much lower level in liver than in adipose tissue, PPARγ agonists exert various PPARγ-dependent effects in liver in addition to PPARγ-independent effects. Differences in effects are dependent on the choice of agonist and experimental conditions in rodent animal studies and in rodent and human liver cell cultures. These effects are much more pronounced in obese and diabetic liver. Moreover, our own recent studies have shown major interindividual variability in the response of primary human hepatocyte populations to troglitazone treatment, supporting the occurrence of hepatotoxicity in only some individuals

Comparative Localization and Functional Activity of the Main Hepatobiliary Transporters in HepaRG Cells and Primary Human Hepatocytes

The role of hepatobiliary transporters in drug-induced liver injury remains poorly understood. Various invivo and invitro biological approaches are currently used for studying hepatic transporters; however, appropriate localization and functional activity of these transporters are essential for normal biliary flow and drug transport. Human hepatocytes (HHs) are considered as the most suitable invitro cell model but erratic availability and inter-donor functional variations limit their use. In this work, we aimed to compare localization of influx and efflux transporters and their functional activity in differentiated human HepaRG hepatocytes with fresh HHs in conventional (CCHH) and sandwich (SCHH) cultures. All tested influx and efflux transporters were correctly localized to canalicular [bile salt export pump (BSEP), multidrug resistance-associated protein 2 (MRP2), multidrug resistance protein 1 (MDR1), and MDR3] or basolateral [Na+-taurocholate co-transporting polypeptide (NTCP) and MRP3] membrane domains and were functional in all models. Contrary to other transporters, NTCP and BSEP were less abundant and active in HepaRG cells, cellular uptake of taurocholate was 2.2- and 1.4-fold and bile excretion index 2.8- and 2.6-fold lower, than in SCHHs and CCHHs, respectively. However, when taurocholate canalicular efflux was evaluated in standard and divalent cation-free conditions in buffers or cell lysates, the difference between the three models did not exceed 9.3%. Interestingly, cell imaging showed higher bile canaliculi contraction/relaxation activity in HepaRG hepatocytes and larger bile canaliculi networks in SCHHs. Altogether, our results bring new insights in mechanisms involved in bile acids accumulation and excretion in HHs and suggest that HepaRG cells represent a suitable model for studying hepatobiliary transporters and drug-induced cholestasi

Transcripts of ceruloplasmin but not hepcidin, both major iron metabolism genes, exhibit a decreasing pattern along portocentral axis of mouse liver

International audienc

General review on in vitro hepatocyte models and their applications.

International audienceIn vitro hepatocyte models represent very useful systems in both fundamental research and various application areas. Primary hepatocytes appear as the closest model for the liver in vivo. However, they are phenotypically unstable, have a limited life span and in addition, exhibit large interdonor variability when of human origin. Hepatoma cell lines appear as an alternative but only the HepaRG cell line exhibits various functions, including major cytochrome P450 activities, at levels close to those found in primary hepatocytes. In vitro hepatocyte models have brought a substantial contribution to the understanding of the biochemistry, physiology, and cell biology of the normal and diseased liver and in various application domains such as xenobiotic metabolism and toxicity, virology, parasitology, and more generally cell therapies. In the future, new well-differentiated hepatocyte cell lines derived from tumors or from either embryonic or adult stem cells might be expected and although hepatocytes will continue to be used in various fields, these in vitro liver models should allow marked advances, especially in cell-based therapies and predictive and mechanistic hepatotoxicity of new drugs and other chemicals. All models will benefit from new developments in throughput screening based on cell chips coupled with high-content imaging and in toxicogenomics technologies

Implication de protéines kinases et phosphatases dans la régulation de l'expression de cytochromes P-450 2B par le phénobarbital et l'interleukine-1béta dans les hépatocytes de rat en culture primaire

RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Etude de la toxicité de deux pesticides organochlorés, le méthoxychlore et l'endosulfan séparément ou en mélange sur les cellules hépatiques humaines HepaRG

CAEN-BU Médecine pharmacie (141182102) / SudocLYON1-BU Santé (693882101) / SudocSudocFranceF

Les modèles in vitro utilisés pour évaluer la sécurité des produits cosmétiques

LYON1-BU Santé (693882101) / SudocRENNES1-BU Santé (352382103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

INFLUENCE DE LA CONGELATION SUR LA SURVIE ET LES ACTIVITES FONCTIONNELLES D'HEPATOCYTES HUMAINS ET ANIMAUX IMMOBILISES DANS UN GEL D'ALGINATE (DOCTORAT (BIOLOGIE ET SCIENCES DE LA SANTE))

RENNES1-BU Santé (352382103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Effets de l'oltipraz sur l'expression des cytochromes P-450 et des glutathion transférases extrahépatiques en situation normale et inflammatoire chez le rat

RENNES1-BU Santé (352382103) / SudocSudocFranceF

Effet des catécholamines sur la lignée hépatocytaire humaine HepaRG soumise à un stress de type septique

RENNES1-BU Santé (352382103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF