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Pamela Charbel Bachour

Assistant professor
Life & Earth Sciences department - Section I - Hadath
Speciality: Biology
Specific Speciality: Bio-santé Toxicologie

Education
2010 - 2014: PhD

University of Rennes I and Lebanese University
Toxicology

First class honours

2009 - 2010: Master II

Lebanese University
Bioactive molecules

Very good

2005 - 2006: Master II

Lebanese university
Nutrition and food management

Very good

2001 - 2005: Master I

Lebanese University
Biology

Very good

ResearchInterests
Publications 5 publications
Pamela Bachour-El Azzi, Ahmad Sharanek, Audrey Burban, Ruoya Li, Rémy Le Guével, Ziad Abdel-Razzak, Bruno Stieger, Christiane Guguen-Guillouzo and André Guillouzo Comparative localization and functional activity of the main hepatobiliary transporters in HepaRG cells and primary human hepatocytes Toxicological Sciences 2015

The role of hepatobiliary transporters in drug-induced liver injury remains poorly understood. Various in vivo and in vitro 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 (HH) are considered as the most suitable in vitro cell model but erratic availability and inter-donor functional variations limit their use. In the present work, we aimed to compare localization of influx and efflux transporters and their functional activity in differentiated human HepaRG hepatocytes with fresh HH in conventional (CCHH) and sandwich (SCHH) cultures. All tested influx and efflux transporters were correctly localized to canalicular (BSEP, MRP2, MDR1, MDR3) or basolateral (NTCP, 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 SCHH and CCHH 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 SCHH. Altogether, our results bring new insights in mechanisms involved in bile acids accumulation and excretion in HH and suggest that HepaRG cells represent a suitable model for studying hepatobiliary transporters and drug-induced cholestasis.

Bachour-El Azzi P, Sharanek A, Abdel-Razzak Z, Antherieu S, Al-Attrache H, Savary CC, Lepage S, Morel I, Labbe G, Guguen-Guillouzo C, Guillouzo A. Impact of inflammation on chlorpromazine-induced cytotoxicity and cholestatic features in HepaRG cells. Drug Metab Dispos 2014

Several factors are thought to be implicated in the occurrence of idiosyncratic adverse drug reactions. The present work aimed to question as to whether inflammation is a determinant factor in hepatic lesions induced by chlorpromazine (CPZ) using the human HepaRG cell line. An inflammation state was induced by a 24-hour exposure to proinflammatory cytokines interleukin-6 (IL-6) and IL-1β; then the cells were simultaneously treated with CPZ and/or cytokine for 24 hours or daily for 5 days. The inflammatory response was assessed by induction of C-reactive protein and IL-8 transcripts and proteins as well as inhibition of CPZ metabolism and down-regulation of cytochrome 3A4 (CYP3A4) and CYP1A2 transcripts, two major cytochrome P450 (P450) enzymes involved in its metabolism. Most effects of cotreatments with cytokines and CPZ were amplified or only observed after five daily treatments; they mainly included increased cytotoxicity and overexpression of oxidative stress-related genes, decreased Na(+)-taurocholate cotransporting polypeptide mRNA levels and activity, a key transporter involved in bile acids uptake, and deregulation of several other transporters. However, CPZ-induced inhibition of taurocholic acid efflux and pericanalicular F-actin distribution were not affected. In addition, a time-dependent induction of phospholipidosis was noticed in CPZ-treated cells, without obvious influence of the inflammatory stress. In summary, our results show that an inflammatory state induced by proinflammatory cytokines increased cytotoxicity and enhanced some cholestatic features induced by the idiosyncratic drug CPZ in HepaRG cells. These changes, together with inhibition of P450 activities, could have important consequences if extrapolated to the in vivo situation.

Sharanek A, Azzi PB, Al-Attrache H, Savary CC, Humbert L, Rainteau D, Guguen-Guillouzo C, Guillouzo A. Different dose-dependent mechanisms are involved in early cyclosporine A-induced cholestatic effects in HepaRG cells Toxicol Sci 2014

Mechanisms involved in drug-induced cholestasis in humans remain poorly understood. Although cyclosporine A (CsA) and tacrolimus (FK506) share similar immunosuppressive properties, only CsA is known to cause dose-dependent cholestasis. Here, we have investigated the mechanisms implicated in early cholestatic effects of CsA using the differentiated human HepaRG cell line. Inhibition of efflux and uptake of taurocholate was evidenced as early as 15 min and 1 h respectively after addition of 10μM CsA; it peaked at around 2 h and was reversible. These early effects were associated with generation of oxidative stress and deregulation of cPKC pathway. At higher CsA concentrations (≥50μM) alterations of efflux and uptake activities were enhanced and became irreversible, pericanalicular F-actin microfilaments were disorganized and bile canaliculi were constricted. These changes were associated with induction of endoplasmic reticulum stress that preceded generation of oxidative stress. Concentration-dependent changes were observed on total bile acid disposition, which were characterized by an increase and a decrease in culture medium and cells, respectively, after a 24-h treatment with CsA. Accordingly, genes encoding hepatobiliary transporters and bile acid synthesis enzymes were differently deregulated depending on CsA concentration. By contrast, FK506 induced limited effects only at 25-50μM and did not alter bile canaliculi. Our data demonstrate involvement of different concentration-dependent mechanisms in CsA-induced cholestasis and point out a critical role of endoplasmic reticulum stress in the occurrence of the major cholestatic features.

Anthérieu S, Bachour-El Azzi P, Dumont J, Abdel-Razzak Z, Guguen-Guillouzo C, Fromenty B, Robin MA, Guillouzo A. Oxidative stress plays a major role in chlorpromazine-induced cholestasis in human HepaRG cells Hepatology 2013

Abstract Drugs induce cholestasis by diverse and still poorly understood mechanisms in humans. Early hepatic effects of chlorpromazine (CPZ), a neuroleptic drug known for years to induce intrahepatic cholestasis, were investigated using the differentiated human hepatoma HepaRG cells. Generation of reactive oxygen species (ROS) was detected as early as 15 minutes after CPZ treatment and was associated with an altered mitochondrial membrane potential and disruption of the pericanalicular distribution of F-actin. Inhibition of [3H]-taurocholic acid efflux was observed after 30 minutes and was mostly prevented by N-acetyl cysteine (NAC) cotreatment, indicating a major role of oxidative stress in CPZ-induced bile acid (BA) accumulation. Moreover, 24-hour treatment with CPZ decreased messenger RNA (mRNA) expression of the two main canalicular bile transporters, bile salt export pump (BSEP) and multidrug resistance protein 3 (MDR3). Additional CPZ effects included inhibition of Na+ -dependent taurocholic cotransporting polypeptide (NTCP) expression and activity, multidrug resistance-associated protein 4 (MRP4) overexpression and CYP8B1 inhibition that are involved in BA uptake, basolateral transport, and BA synthesis, respectively. These latter events likely represent hepatoprotective responses which aim to reduce intrahepatic accumulation of toxic BA. Compared to CPZ effects, overloading of HepaRG cells with high concentrations of cholic and chenodeoxycholic acids induced a delayed oxidative stress and, similarly, after 24 hours it down-regulated BSEP and MDR3 in parallel to a decrease of NTCP and CYP8B1 and an increase of MRP4. By contrast, low BA concentrations up-regulated BSEP and MDR3 in the absence of oxidative stress. CONCLUSION: These data provide evidence that, among other mechanisms, oxidative stress plays a major role as both a primary causal and an aggravating factor in the early CPZ-induced intrahepatic cholestasis in human hepatocytes.

Bachour P, Yafawi R, Jaber F, Choueiri E, Abdel-Razzak Z. Effects of smoking, mother's age, body mass index, and parity number on lipid, protein, and secretory immunoglobulin A concentrations of human milk Breastfeed Med 2012

Abstract AIM: This study investigated the effect of smoking, mother's age, body mass index (BMI), and parity number on density, lipids, proteins, and secreted immunoglobulin A (SIgA) of human milk. METHODS: Transitional and mature milk samples were collected from 23 nursing smoker mothers and 43 nursing nonsmoker mothers. Proteins, lipids, and SIgA concentrations were determined as well as the milk density and the general protein profile. RESULTS: Our investigation showed that the milk of smokers contained less lipids and proteins (statistically significant 26% and 12% decrease, respectively), whereas milk density was unchanged. SIgA concentration was 27% lower in milk from smokers, but the decrease was not statistically significant. The general protein profile showed no significant smoking-associated changes in the four identified proteins (β-casein, immunoglobulin A heavy chain, serum albumin, and lactoferrin). Mothers' age and residential area showed noticeable but statistically nonsignificant differences in some of the measured parameters. However, parity number, lactation stage, and BMI were associated with a significant modification of milk composition. Mature milk contained more lipids and less protein, whereas the increase of parity number was associated with an increase in lipid concentration. The group of overweight mothers showed lower milk protein concentration in comparison with the normal group. Multivariate analysis showed a statistically significant interaction effect of the variables (smoking, parity number, lactation stage, age, and BMI) on lipids and between some of them on proteins and SIgA. CONCLUSION: Our study showed that smoking was associated with lower milk lipid and protein concentrations and that the parity number and BMI were associated with a change in milk lipids and proteins content, respectively.

Languages
English

Professional working proficiency

French

Native or bilingual proficiency