Publications by authors named "Philippe Couvert"

28 Publications

  • Page 1 of 1

Phospholipid transfer to high-density lipoprotein (HDL) upon triglyceride lipolysis is directly correlated with HDL-cholesterol levels and is not associated with cardiovascular risk.

Atherosclerosis 2021 Mar 9;324:1-8. Epub 2021 Mar 9.

National Institute for Health and Medical Research (INSERM) UMR_S 1166, Faculty of Medicine Pitie-Salpetriere, 91 Bld de L'Hopital, 75013, Paris, France; Sorbonne University, Paris, France.

Background And Aims: While low concentrations of high-density lipoprotein-cholesterol (HDL-C) represent a well-established cardiovascular risk factor, extremely high HDL-C is paradoxically associated with elevated cardiovascular risk, resulting in the U-shape relationship with cardiovascular disease. Free cholesterol transfer to HDL upon lipolysis of triglyceride-rich lipoproteins (TGRL) was recently reported to underlie this relationship, linking HDL-C to triglyceride metabolism and atherosclerosis. In addition to free cholesterol, other surface components of TGRL, primarily phospholipids, are transferred to HDL during lipolysis. It remains indeterminate as to whether such transfer is linked to HDL-C and cardiovascular disease.

Methods And Results: When TGRL was labelled with fluorescent phospholipid 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI), time- and dose-dependent transfer of DiI to HDL was observed upon incubations with lipoprotein lipase (LPL). The capacity of HDL to acquire DiI was decreased by -36% (p<0.001) in low HDL-C patients with acute myocardial infarction (n = 22) and by -95% (p<0.001) in low HDL-C subjects with Tangier disease (n = 7), unchanged in low HDL-C patients with Type 2 diabetes (n = 17) and in subjects with high HDL-C (n = 20), and elevated in subjects with extremely high HDL-C (+11%, p<0.05) relative to healthy normolipidemic controls. Across all the populations combined, HDL capacity to acquire DiI was directly correlated with HDL-C (r = 0.58, p<0.001). No relationship of HDL capacity to acquire DiI with both overall and cardiovascular mortality obtained from epidemiological studies for the mean HDL-C levels observed in the studied populations was obtained.

Conclusions: These data indicate that the capacity of HDL to acquire phospholipid from TGRL upon LPL-mediated lipolysis is proportional to HDL-C and does not reflect cardiovascular risk in subjects widely differing in HDL-C levels.
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http://dx.doi.org/10.1016/j.atherosclerosis.2021.03.002DOI Listing
March 2021

Ablation of DNA-methyltransferase 3A in skeletal muscle does not affect energy metabolism or exercise capacity.

PLoS Genet 2021 Jan 29;17(1):e1009325. Epub 2021 Jan 29.

Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.

In response to physical exercise and diet, skeletal muscle adapts to energetic demands through large transcriptional changes. This remodelling is associated with changes in skeletal muscle DNA methylation which may participate in the metabolic adaptation to extracellular stimuli. Yet, the mechanisms by which muscle-borne DNA methylation machinery responds to diet and exercise and impacts muscle function are unknown. Here, we investigated the function of de novo DNA methylation in fully differentiated skeletal muscle. We generated muscle-specific DNA methyltransferase 3A (DNMT3A) knockout mice (mD3AKO) and investigated the impact of DNMT3A ablation on skeletal muscle DNA methylation, exercise capacity and energy metabolism. Loss of DNMT3A reduced DNA methylation in skeletal muscle over multiple genomic contexts and altered the transcription of genes known to be influenced by DNA methylation, but did not affect exercise capacity and whole-body energy metabolism compared to wild type mice. Loss of DNMT3A did not alter skeletal muscle mitochondrial function or the transcriptional response to exercise however did influence the expression of genes involved in muscle development. These data suggest that DNMT3A does not have a large role in the function of mature skeletal muscle although a role in muscle development and differentiation is likely.
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http://dx.doi.org/10.1371/journal.pgen.1009325DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875352PMC
January 2021

COVID-19-associated collapsing glomerulopathy: a report of two cases and literature review.

Intern Med J 2020 12;50(12):1551-1558

Service de Medecine Interne 2, Institut E3M, Sorbonne University, Assistance Publique-Hôpitaux de Paris, Groupement Hospitalier Pitié-Salpêtrière, Paris, France.

Nephrotic range proteinuria has been reported during the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and coronavirus disease (COVID-19). However, the pathological mechanisms underlying this manifestation are unknown. In this article, we present two cases of collapsing glomerulopathy (CG) associated with acute tubular necrosis during the course of COVID-19, and review the literature for similar reports. In our two cases, as in the 14 cases reported so far, the patients were of African ancestry. The 14 patients assessed had an APOL1 high-risk genotype. At the end of the reported period, two patients had died and five patients were still requiring dialysis. The 16 cases detailed in the present report strongly argue in favour of a causal link between SARS-CoV-2 infection and the occurrence of CG in patients homozygous for APOL1 high-risk genotype for which the term COVID-associated nephropathy (COVIDAN) can be put forward.
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http://dx.doi.org/10.1111/imj.15041DOI Listing
December 2020

Free cholesterol transfer to high-density lipoprotein (HDL) upon triglyceride lipolysis underlies the U-shape relationship between HDL-cholesterol and cardiovascular disease.

Eur J Prev Cardiol 2020 10 15;27(15):1606-1616. Epub 2019 Dec 15.

National Institute for Health and Medical Research (INSERM) UMR_S 1166, Faculty of Medicine Pitié-Salpétrière, Paris, France.

Background: Low concentrations of high-density lipoprotein cholesterol (HDL-C) represent a well-established cardiovascular risk factor. Paradoxically, extremely high HDL-C levels are equally associated with elevated cardiovascular risk, resulting in the U-shape relationship of HDL-C with cardiovascular disease. Mechanisms underlying this association are presently unknown. We hypothesised that the capacity of high-density lipoprotein (HDL) to acquire free cholesterol upon triglyceride-rich lipoprotein (TGRL) lipolysis by lipoprotein lipase underlies the non-linear relationship between HDL-C and cardiovascular risk.

Methods: To assess our hypothesis, we developed a novel assay to evaluate the capacity of HDL to acquire free cholesterol (as fluorescent TopFluor® cholesterol) from TGRL upon in vitro lipolysis by lipoprotein lipase.

Results: When the assay was applied to several populations markedly differing in plasma HDL-C levels, transfer of free cholesterol was significantly decreased in low HDL-C patients with acute myocardial infarction (-45%) and type 2 diabetes (-25%), and in subjects with extremely high HDL-C of >2.59 mmol/L (>100 mg/dL) (-20%) versus healthy normolipidaemic controls. When these data were combined and plotted against HDL-C concentrations, an inverse U-shape relationship was observed. Consistent with these findings, animal studies revealed that the capacity of HDL to acquire cholesterol upon lipolysis was reduced in low HDL-C apolipoprotein A-I knock-out mice and was negatively correlated with aortic accumulation of [H]-cholesterol after oral gavage, attesting this functional characteristic as a negative metric of postprandial atherosclerosis.

Conclusions: Free cholesterol transfer to HDL upon TGRL lipolysis may underlie the U-shape relationship between HDL-C and cardiovascular disease, linking HDL-C to triglyceride metabolism and atherosclerosis.
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http://dx.doi.org/10.1177/2047487319894114DOI Listing
October 2020

Identification of the first Tangier disease patient in Lebanon carrying a new pathogenic variant in ABCA1.

J Clin Lipidol 2018 Nov - Dec;12(6):1374-1382. Epub 2018 Sep 1.

Laboratory of Biochemistry and Molecular Therapeutics, Faculty of Pharmacy, Pôle Technologie- Santé, Saint Joseph University, Beirut, Lebanon; INSERM LVTS U1148, Hôpital Bichat-Claude Bernard, Paris, France. Electronic address:

Background: The Middle East region is characterized by low levels of high-density lipoprotein cholesterol (HDL-C). To date, no genetic study has investigated the cause of low HDL-C in the Lebanese population.

Objective: Our objective was to study the genetic causes for hypoalphalipoproteinemia in a Lebanese family with extremely low HDL-C levels.

Methods: We sequenced the ABCA1 gene and evaluated cholesterol efflux, inflammatory, and metabolic profiles in the proband and his family.

Results: We identified the first Lebanese pathogenic variant in ABCA1 gene causing Tangier disease in a consanguineous family. The proband carried a novel homozygous pathogenic variant p.Gly592Asp in exon 14 of ABCA1, which segregated with the disease in the family. Functional study of the p.Gly592Asp pathogenic variant revealed that lipid-free apolipoprotein A-I-dependent cholesterol efflux was completely abolished in cholesterol-loaded human monocytes-derived macrophages isolated from the proband when compared to controls. Systemic inflammatory and metabolic assessments showed that plasma cytokines (MCP-1, MIP-1α, IL-6, CRP, TNF-α), adhesion molecules (ICAM-1, VCAM-1, E-selectin), inflammatory soluble receptors (sIL-6r, sTNFRI, sTNFRII), and metabolic markers (Insulin, C-peptide) were elevated in the proband when compared to controls. Noninvasive cardiovascular investigation revealed the presence of premature artery lesions in the proband.

Conclusions: It is the first case of Tangier disease reported in Lebanon harboring a novel pathogenic variant in ABCA1. Further genetic research is needed in the Middle East where the consanguinity rate is elevated, to understand the cause of the highly prevalent dyslipidemia. This will help guiding the early diagnosis, management, and prevention of cardiovascular complications.
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http://dx.doi.org/10.1016/j.jacl.2018.08.013DOI Listing
October 2019

The usefulness of advanced lipid and oxidative stress testing for diagnosis and management of low HDL-cholesterol phenotype: A case report.

Clin Biochem 2017 Dec 23;50(18):1323-1325. Epub 2017 Jun 23.

Hôpitaux Universitaires Pitié-Salpêtrière-Charles Foix, Pôle de Biologie Médicale et Pathologie, Centre de Génétique Moléculaire et Chromosomique, Bd de l'Hôpital 47, Paris, France.

Objective: Plasma high-density lipoprotein cholesterol (HDL-C) level is a strong inverse predictor of cardiovascular disease (CVD) development. Tangier disease, a consequence of mutations in the ATP binding cassette transporter 1 (ABCA1) gene, is associated with very low HDL-C levels. Still, the relationship between Tangier disease and CVD is not always evident. The study investigates usefulness of lipoprotein subfractions, oxidative stress and paraoxonase 1 (PON1) status assessment for evaluation and management of patient with low HDL-C phenotype.

Patient And Methods: A 12-year-old boy was hospitalised due to hypertension. Laboratory evaluation revealed low HDL-C level, and subsequent molecular diagnostic confirmed Tangier disease. Lipoprotein subfractions were assessed by gradient-gel electrophoresis. Oxidative stress status was estimated by measuring total antioxidative status, total oxidative status, prooxidative-antioxidative balance, malondialdehyde and advanced oxidation protein products levels. Activity of paraoxonase 1 in serum and its distribution within HDL subclasses was also determined (ten healthy boys aged 13.1±3.4years served as the reference group).

Results: Analysis of oxidative stress status biomarkers revealed a state of prolonged prooxidants activity. In turn, serum PON1 activity was substantially reduced. The majority of PON1 activity was present on HDL 2 particles.

Conclusion: Impaired antioxidative potential of HDL may point toward hidden cardiovascular risk in isolated low HDL-phenotype.
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http://dx.doi.org/10.1016/j.clinbiochem.2017.06.007DOI Listing
December 2017

Natural history of cerebrotendinous xanthomatosis: a paediatric disease diagnosed in adulthood.

Orphanet J Rare Dis 2016 Apr 16;11:41. Epub 2016 Apr 16.

AP-HP, UF Neurométabolique Bioclinique et Génétique, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.

Cerebrotendinous xanthomatosis (CTX) is among the few inherited neurometabolic disorders amenable to specific treatment. It is easily diagnosed using plasma cholestanol. We wished to delineate the natural history of the most common neurological and non-neurological symptoms in thirteen patients with CTX. Diarrhea almost always developed within the first year of life. Cataract and school difficulties usually occurred between 5 and 15 years of age preceding by years the onset of motor or psychiatric symptoms. The median age at diagnosis was 24.5 years old. It appears critical to raise awareness about CTX among paediatricians in order to initiate treatment before irreversible damage occurs.
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http://dx.doi.org/10.1186/s13023-016-0419-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4833925PMC
April 2016

Extended-Release Niacin/Laropiprant Improves Overall Efficacy of Postprandial Reverse Cholesterol Transport.

Arterioscler Thromb Vasc Biol 2016 Feb 17;36(2):285-94. Epub 2015 Dec 17.

From the INSERM, Sorbonne Universités, UPMC Univ Paris 06, UMRS-1166 Hôpital de la Pitié, Paris, France (P.E.K., T.H., J.G., P.C., J.-M.L., E.F., P.L., W.L.G., M.G.); University Saint-Joseph, Beyrouth, Lebanon (P.E.K.); ICAN-Institute of CardioMetabolism and Nutrition, Hôpital de la Pitié, Paris, France (T.H., P.C., J.-M.L., E.F., P.L., W.L.G., M.G.); University of Munich, Munich, Germany (E.W., K.G.P.); and INSERM, Emeritus Research Director (J.C.).

Objectives: Postprandial atherogenic lipoproteins, characterizing high-risk patients, correlate positively with cardiovascular events. Although the effect of niacin on fasting lipids is well established, its impact on atheroprotective reverse cholesterol transport (RCT) pathway and on functional features of circulating lipoproteins during the postprandial state remains indeterminate.

Approach And Results: We evaluated RCT pathway during postprandial phase in dyslipidemic patients displaying a low high-density lipoprotein (HDL) cholesterol phenotype. Ten subjects on stable statin therapy received 1 g/20 mg extended-release niacin/laropiprant (ERN/LRPT) for 4 weeks followed by 2 g/40 mg ERN/LRPT for additional 8 weeks. At each experimental period, postprandial hypertriglyceridemia and major steps of RCT, including cholesterol efflux from human macrophages, cholesteryl ester transfer protein-mediated cholesteryl ester transfer, and hepatic HDL-cholesteryl ester selective uptake were evaluated. Equally, the capacity of postprandial HDL particles isolated from patients before and after ERN/LRPT treatment to mediate RCT to feces was evaluated in vivo in human apolipoprotein B/cholesteryl ester transfer protein double transgenic mouse model. Compared with baseline, ERN/LRPT significantly reduced postprandial hypertriglyceridemia (incremental area under the curve-triglyceride: -53%; P=0.02). Postprandial increase in endogenous plasma cholesteryl ester transfer protein activity was completely abolished after ERN/LRPT treatment. Despite a slight reduction in plasma cholesterol efflux capacity from human THP-1 macrophages, evaluation of global RCT efficacy by combining both ex vivo and in vivo approaches indicate that postprandial HDL particles formed under ERN/LRPT therapy displayed a greater capacity for HDL-mediated RCT to feces.

Conclusions: ERN/LRPT treatment efficiently attenuates atherogenic postprandial lipemia and stimulates HDL-mediated cholesterol return to the liver and elimination into feces during postprandial phase, thus maintaining an efficient removal of cholesterol from the body.
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http://dx.doi.org/10.1161/ATVBAHA.115.306834DOI Listing
February 2016

Adrenocortical scavenger receptor class B type I deficiency exacerbates endotoxic shock and precipitates sepsis-induced mortality in mice.

J Immunol 2014 Jul 16;193(2):817-26. Epub 2014 Jun 16.

INSERM Unité Mixte de Recherche_S 1166, Hôpital de la Pitié-Salpêtrière, F-75013, Paris, France; Université Pierre et Marie Curie 06, Unité Mixte de Recherche_S 1166, F-75013, Paris, France; Institute of Cardiometabolism and Nutrition, F-75013, Paris, France; and Assistance Publique-Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Service d'Endocrinologie-Métabolisme, F-75013 Paris, France

Scavenger receptor class B type I (SR-BI)-deficient mice display reduced survival to endotoxic shock and sepsis. The understanding of the mechanisms underlying SR-BI protection has been hampered by the large spectrum of SR-BI functions and ligands. It notably plays an important role in the liver in high-density lipoprotein metabolism, but it is also thought to participate in innate immunity as a pattern recognition receptor for bacterial endotoxins, such as LPS. In this study, we sought to determine the tissue-specific contribution of SR-BI in the hyperinflammatory response and high mortality rates observed in SR-BI(-/-) mice in endotoxicosis or sepsis. Restoring plasma levels of high-density lipoprotein, which are critical lipoproteins for LPS neutralization, did not improve acute outcomes of LPS injection in SR-BI(-/-) mice. Mice deficient for SR-BI in hepatocytes, endothelial cells, or myeloid cells were not more susceptible to LPS-induced death. However, if SR-BI ablation in hepatocytes led to a moderate increase in systemic inflammatory markers, SR-BI deficiency in myeloid cells was associated with an anti-inflammatory effect. Finally, mice deficient for SR-BI in the adrenal cortex, where the receptor provides lipoprotein-derived cholesterol, had impaired secretion of glucocorticoids in response to stress. When exposed to an endotoxin challenge, these mice exhibited an exacerbated systemic and local inflammatory response, reduced activation of atrophy genes in muscle, and high lethality rate. Furthermore, polymicrobial sepsis induced by cecal ligature and puncture resulted in early death of these animals. Our study clearly demonstrates that corticoadrenal SR-BI is a critical element of the hypothalamic-pituitary-adrenal axis to provide effective glucocorticoid-dependent host defense after an endotoxic shock or bacterial infection.
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http://dx.doi.org/10.4049/jimmunol.1303164DOI Listing
July 2014

Endogenous CETP activity as a predictor of cardiovascular risk: determination of the optimal range.

Atherosclerosis 2013 Mar 2;227(1):165-71. Epub 2013 Jan 2.

INSERM UMRS939, Hôpital de la Pitié, Paris, France.

Objectives: To identify key determinants of plasma endogenous CETP activity and threshold value of plasma CETP activity associated with high cardiovascular risk.

Methods: Endogenous plasma CETP activity was measured in a total of 1403 individuals.

Results: Multivariate analysis revealed that 23.5% of endogenous CETP activity variability was explained by plasma LDL-C (12.0%), HDL-C (6.4%) and TG (4.4%) whereas sex and BMI accounted together for only 0.7% of its variability. Scoring patients for cardiovascular risk on the basis of their plasma lipid levels (TC, TG, LDL-C and HDL-C), revealed that patients with high cardiovascular risk (score ≥3) displayed a mean endogenous plasma CETP activity above 34%.

Conclusion: Plasma CETP activity represents a potent indicator of cardiovascular risk in patients with metabolic disorders since it integrates major independent risk factors.
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http://dx.doi.org/10.1016/j.atherosclerosis.2012.12.024DOI Listing
March 2013

Myoclonus and dystonia in cerebrotendinous xanthomatosis.

Mov Disord 2012 Dec 31;27(14):1805-10. Epub 2012 Oct 31.

AP-HP Département de Neurologie, Hôpital de la Salpêtrière, Paris, France.

Background: Cerebrotendinous xanthomatosis (CTX) is an inherited neurometabolic disorder. The main neurological manifestations of the disease are pyramidal syndrome, ataxia, peripheral neuropathy, cognitive impairment, epilepsy, and psychiatric disturbances. Myoclonic dystonia has been reported on in the setting of various neurometabolic diseases. Anecdotal reports describe movement disorders associated with CTX, but no dystonia with myoclonic events.

Methods: We collected clinical, biochemical, electrophysiological, neuroradiological, and genetic data of 6 patients with myoclonus and mild dystonia associated with CTX. From a systematic literature review, we analyzed 31 patients with movement disorders secondary to CTX.

Results: Our 6 patients presented distal myoclonus with mild dystonia of the upper limbs. Myoclonus was of subcortical origin, based on neurophysiological recordings, and differed from oromandibular myoclonus previously described in CTX patients.

Conclusions: These results expand the phenotype of CTX and suggest that myoclonus and/or dystonia are underdiagnosed. In keeping with our findings, tremors previously observed in CTX patients might actually correspond to myoclonic events. We hypothesize that a dysfunction of the dentate nuclei-basal ganglia pathway may be involved.
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http://dx.doi.org/10.1002/mds.25206DOI Listing
December 2012

Insulin-like growth factor 2 gene methylation in peripheral blood mononuclear cells of patients with hepatitis C related cirrhosis or hepatocellular carcinoma.

Clin Res Hepatol Gastroenterol 2012 Aug 16;36(4):345-51. Epub 2012 Aug 16.

Inserm U939, Dyslipidemia, Inflammation and Atherosclerosis in metabolic diseases, 75013 Paris, France.

Unlabelled: Igf2 gene specific hypomethylation has been demonstrated in hepatocellular carcinoma (HCC) cells and in non-tumoral liver samples from patients with HCV-related cirrhosis who further developed HCC. In patients with colorectal cancers, Igf2 hypomethylation is found in peripheral blood mononuclear cells (PBMC) even prior to the occurrence of cancer.

Aim: To compare Igf2 methylation in PBMC from healthy donors and patients with HCV-related cirrhosis without or with history of HCC.

Patients And Methods: After DNA extraction from frozen PBMC samples of 52 healthy blood donors and 121 patients with HCV-related cirrhosis either without (n=59) or with past or present HCC (n=62), and sodium bisulfite treatment, unbiased PCR amplification and Denaturing High Performance Liquid Chromatography (DHPLC) analysis were used for methylation analysis at the differentially methylated region 2 of Igf2. Methylation profiles were classified in three groups (unmethylated, U; methylated, M; and intermediate, UM) according to the proportions of M and U alleles, blindly to clinical data. In addition, 677C-T mutation of Methylenetetrahydrofolate Reductase (MTHFR) was investigated by fluorescent probes.

Results: Prevalences of U, UM and M Igf2 profiles were: 8%, 65% and 27% in blood donors, 0%, 81% and 19% in patients with HCV-related cirrhosis without HCC, 71%, 29% and 0% in patients with HCC (P<0.0001). Igf2 methylation profile was independent from gender, age, body mass index, and presence of 677C-T mutation of MTHFR.

Conclusion: These observations suggest a decrease of Igf2 methylation from cirrhosis to HCC in patients with HCV infection, which may be an additional risk factor for HCC.
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http://dx.doi.org/10.1016/j.clinre.2012.06.013DOI Listing
August 2012

Identification and characterization of new gain-of-function mutations in the PCSK9 gene responsible for autosomal dominant hypercholesterolemia.

Atherosclerosis 2012 Aug 17;223(2):394-400. Epub 2012 May 17.

Institut National de la Santé et de la Recherche Médicale, Inserm UMR698, Hemostasis, Bio-Engineering and Cardiovascular Remodelling, Hôpital Bichat-Claude Bernard, 46 Rue Henri Huchard, 75877 Paris Cedex 18, France.

Background: The identification of mutations in PCSK9 (proprotein convertase subtilisin kexin9) in autosomal dominant hypercholesterolemia (ADH), has revealed the existence of a new player in cholesterol homeostasis. PCSK9 has been shown to enhance the degradation of the LDL receptor (LDLR) at the cell surface. Gain-of-function mutations of PCSK9 induce ADH and are very rare, but their identification is crucial in studying PCSK9's role in hypercholesterolemia, its detailed trafficking pathway and its impact on the LDLR.

Methods: In order to identify new mutations and understand the exact mechanisms of action of mutated PCSK9, PCSK9 was sequenced in 75 ADH patients with no mutations in the LDLR or APOB genes. Functional analyses in cell culture were conducted and the impact of novel PCSK9 mutations on the quantitative and qualitative features of lipoprotein particles and on the HDL-mediated cellular cholesterol efflux was studied.

Results: Among these 75 ADH probands with no mutations in the LDLR or APOB genes, four gain-of-function mutations of PCSK9 were identified, of which two were novel: the p.Leu108Arg and the p.Asp35Tyr substitutions. In vitro studies of their consequences on the activity of PCSK9 on cell surface levels of LDLR showed that the p.Leu108Arg mutation clearly results in a gain-of-function, while the p.Asp35Tyr mutation created a novel Tyr-sulfation site, which may enhance the intracellular activity of PCSK9.

Conclusion: These data further contribute to the characterization of PCSK9 mutations and to better understanding of the impact on cholesterol metabolism of this new therapeutic target.
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http://dx.doi.org/10.1016/j.atherosclerosis.2012.04.006DOI Listing
August 2012

Clinical and electrophysiological characteristics of neuropathy associated with Tangier disease.

J Neurol 2012 Jun 17;259(6):1222-6. Epub 2011 Dec 17.

Service de Neurologie Neurovasculaire, Groupe Hospitalier Paris-Saint Joseph, 185 rue Raymond Losserand, 75014 Paris, France.

Tangier disease (TD) (OMIM#205400) is a rare autosomal recessive disorder resulting from mutations in the ABCA1 gene, leading to decreased levels of plasma high-density lipoproteins (HDL). Peripheral neuropathy is a common finding in this disease, and may present as relapsing/remitting mono/polyneuropathies or as syringomyelia-like neuropathy. We retrospectively analyzed four patients, and report here their clinical, biological, electrophysiological, imaging, and genetic findings. Three patients had a typical pseudosyringomyelic neuropathy including facial diplegia, but asymmetrical onset was observed in one patient who had first been misdiagnosed with Lewis-Sumner syndrome. Electrophysiological pattern was heterogeneous, showing both signs of demyelination and axonal degeneration. Truncating mutations of the ABCA1 gene, including two previously undescribed mutations, were constantly found. Atypical symptom onset and demyelinating features on electrophysiological examination can be misleading in case of pseudosyringomyelic neuropathy. These reports illustrate two different neurological phenotypes in TD, namely the pseudosyringomyelic type and the Lewis-Sumner-like type, and advocate for a systematic assessment of lipid profile including HDL cholesterol in demyelinating neuropathies.
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http://dx.doi.org/10.1007/s00415-011-6340-2DOI Listing
June 2012

Plasma bilirubin and gamma-glutamyltransferase activity are inversely related in dyslipidemic patients with metabolic syndrome: relevance to oxidative stress.

Atherosclerosis 2010 Jun 29;210(2):607-13. Epub 2009 Dec 29.

Unités de Prévention Cardiovasculaire, Service d'Endocrinologie-Métabolisme, Assistance Publique/Hopitaux de Paris, Groupe Hospitalier Pitié-Salpétrière-Université Pierre et Marie Curie, France.

Background: Subnormal levels of plasma bilirubin levels are associated with premature coronary artery disease and cardiovascular morbidity. Plasma gamma-glutamyltransferase (GGT) activity is linked to bilirubin level in hepatic disease and elevated GGT is equally associated with hepatic steatosis, a frequent feature of metabolic syndrome (MS). In order to assess the potential relationship between GGT activity and bilirubin levels in subjects exhibiting features of the metabolic syndrome, we determined circulating bilirubin levels and GGT activity in a cohort of dyslipidemic patients.

Methods And Results: This cross-sectional study involved patients (n=1433) displaying atherogenic dyslipidemia in primary prevention referred to our Prevention Center. Among these patients, 25% presented with MS as defined by recent NCEP ATP III criteria. Circulating levels of transaminases, as well as GGT activity, were elevated in MS patients; by contrast, bilirubin concentrations were significantly lower in such patients as compared to those lacking this syndrome (p<10-4 for all comparisons). Comparisons of patient groups on the basis of the number of MS criteria which were concomitantly present revealed a progressive decrease in mean bilirubin levels; this reduction paralleled a progressive increase in mean GGT activity as a function of the number of MS components in the overall population (p value for trend<10-4).

Conclusion: Elevation in systemic GGT activity, which is characterized by extended generation of ROS, together with potentially deficient bilirubin-mediated antioxidative capacity of plasma, may therefore constitute key components of the systemic oxidative stress typical of metabolic syndrome.
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http://dx.doi.org/10.1016/j.atherosclerosis.2009.12.026DOI Listing
June 2010

Stimulation of cholesterol efflux by LXR agonists in cholesterol-loaded human macrophages is ABCA1-dependent but ABCG1-independent.

Arterioscler Thromb Vasc Biol 2009 Nov 3;29(11):1930-6. Epub 2009 Sep 3.

INSERM UMR S939, Paris, France.

Objective: Maintenance of cholesterol homeostasis in human macrophages is essential to prevent foam cell formation. We evaluated the relative contribution of the ABCA1 and ABCG1 transporters to cholesterol efflux from human macrophages, and of the capacity of LXR agonists to reduce foam cell formation by stimulating export of cellular cholesterol.

Methods And Results: ABCG1 mRNA levels were strongly increased in acLDL-loaded THP-1 macrophages and in HMDM on stimulation with LXR agonists. However, silencing of ABCG1 expression using ABCG1-specific siRNA indicated that ABCG1 was not essential for cholesterol efflux to HDL in cholesterol-loaded human macrophages stimulated with LXR agonists. Indeed, ABCA1 was solely responsible for the stimulation of cholesterol efflux to HDL on LXR activation, as this effect was abolished in HMDM from Tangier patients. Furthermore, depletion of cellular ATP indicated that the LXR-induced export of cholesterol was an ATP-dependent transport mechanism in human macrophages. Finally, use of an anti-Cla-1 blocking antibody identified the Cla-1 receptor as a key component in cholesterol efflux to HDL from cholesterol-loaded human macrophages.

Conclusions: Our data indicate that stimulation of cholesterol efflux to HDL by LXR agonists in human foam cells involves an ATP-dependent transport mechanism mediated by ABCA1 that it appears to be independent of ABCG1 expression.
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http://dx.doi.org/10.1161/ATVBAHA.109.194548DOI Listing
November 2009

Liver insulin-like growth factor 2 methylation in hepatitis C virus cirrhosis and further occurrence of hepatocellular carcinoma.

World J Gastroenterol 2008 Sep;14(35):5419-27

Department of Hepato-Gastroenterology, Jean Verdier Hospital, AP-HP, Bondy, France.

Aim: To assess the predictive value of the insulin-like growth factor 2 (Igf2) methylation profile for the occurrence of Hepatocellular Carcinoma (HCC) in hepatitis C (HCV) cirrhosis.

Methods: Patients with: (1) biopsy-proven compensated HCV cirrhosis; (2) available baseline frozen liver sample; (3) absence of detectable HCC; (4) regular screening for HCC; (5) informed consent for genetic analysis were studied. After DNA extraction from liver samples and bisulfite treatment, unbiased PCR and DHPLC analysis were performed for methylation analysis at the Igf2 locus. The predictive value of the Igf2 methylation profile for HCC was assessed by Kaplan-Meier and Cox methods.

Results: Among 94 included patients, 20 developed an HCC during follow-up (6.9 +/- 3.2 years). The methylation profile was hypomethylated, intermediate and hypermethylated in 13, 64 and 17 cases, respectively. In univariate analysis, two baseline parameters were associated with the occurrence of HCC: age (P = 0.01) and prothrombin (P = 0.04). The test of linear tendency between the three ordered levels of Igf2 methylation and probability of HCC occurrence was significant (Log Rank, P = 0.043; Breslow, P = 0.037; Tarone-Ware, P = 0.039).

Conclusion: These results suggest that hypomethylation at the Igf2 locus in the liver could be predictive for HCC occurrence in HCV cirrhosis.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2744164PMC
http://dx.doi.org/10.3748/wjg.14.5419DOI Listing
September 2008

Association between a frequent allele of the gene encoding OATP1B1 and enhanced LDL-lowering response to fluvastatin therapy.

Pharmacogenomics 2008 Sep;9(9):1217-27

INSERM, UMR S551, Dyslipoproteinemia and Atherosclerosis Research Unit, Hôpital de la Pitié, F-75013, Paris, France.

Introduction: Marked lowering of low-density-lipoprotein cholesterol (LDL-C) levels (< or =50%) with intensive statin therapy is associated with major reduction in cardiovascular risk, but is limited by a potential increase in adverse effects, thereby justifying optimization of LDL-C reduction with minimal risk. The organic anion transporting polypeptide-1B1 encoded by the SLCO1B1 gene is implicated as a major transporter in cellular uptake of statins, and notably fluvastatin. We postulated that genetic variation in SLCO1B1 might affect statin bioavailability, and might therefore influence drug response and potential adverse effects.

Materials & Methods: Elderly hypercholesterolemic subjects (n = 724), whose plasma lipid profile was determined before and 2 months after fluvastatin extended-release treatment (80 mg/day, n = 420), or placebo (n = 304), were genotyped for the most frequent nonsynonymous polymorphisms (SNP) in the SLCO1B1 gene (c.388A>G, c.463C>A and c.521T>C).

Results: Due to linkage disequilibrium, only four alleles (*1b, *5, *14 and *15) of SLCO1B1 were detected in addition to the wild-type allele (*1a). The c.463A genotype, which was systematically associated with the c.388G SNP corresponding to the *14 allele was significantly associated with percentage LDL-C reduction from baseline (p = 0.005) and with mean post-treatment LDL-C values (p = 0.0005). Subjects homozygous for the c.463C genotype (n = 294) exhibited significantly less LDL-C reduction and higher post-treatment LDL-C levels (-31.5%, 138 mg/dl) relative to heterozygous C/A patients (-36.2%, 126 mg/dl; n = 111), and to homozygous A/A subjects (-41%, 115 mg/dl; n = 15).

Conclusions: These results reveal that OATP1B1 is implicated in the pharmacological action and efficacy of fluvastatin. Indeed, the common *14 allele, which is distinguished by the presence of the c.463C>A polymorphism, was associated with enhanced lipid-lowering efficacy in this study.
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http://dx.doi.org/10.2217/14622416.9.9.1217DOI Listing
September 2008

Lewis-Sumner syndrome and Tangier disease.

Arch Neurol 2008 Jul;65(7):968-70

Fédération de Neurologie, Prs Lyon-Caen et Meininger, Hôpital Pitié-Salpêtrière, F-75651 Paris, France.

Objective: To report unusual electrophysiologic data in a patient with Tangier disease in an effort to better understand the pathophysiologic features of the peripheral nerve lesions in this disease.

Design: Case report.

Patient: A 15-year-old girl had subacute onset of asymmetric neuropathy with persistent conduction block, resembling Lewis-Sumner syndrome.

Main Outcome Measures: Electrophysiologic data in Tangier disease.

Results: After initially unsuccessful treatment with intravenously administered immunoglobulins, the finding of an abnormal lipid profile led to the diagnosis of Tangier disease due to the R587W mutation in the adenotriphosphate-binding cassette transporter-1 gene (ABCA1) (OMIM 9q22-q31).

Conclusions: Conduction block, which is the electrophysiologic hallmark of focal demyelination, can be present in Tangier disease. It could be induced by focal nerve ischemia or by preferential lipid deposition in the paranodal regions of myelinated Schwann cells. The presence of a conduction block in Tangier disease may lead to a misdiagnosis of dysimmune neuropathy.
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http://dx.doi.org/10.1001/archneur.65.7.968DOI Listing
July 2008

Liver iron, HFE gene mutations, and hepatocellular carcinoma occurrence in patients with cirrhosis.

Gastroenterology 2008 Jan 26;134(1):102-10. Epub 2007 Oct 26.

Service d'Hépato-gastroentérologie, Hôpital Jean Verdier, Assistance Publique-Hôpitaux de Paris, Bondy, France.

Background & Aims: The influence of HFE gene mutations and liver iron overload on hepatocellular carcinoma (HCC) occurrence in patients with cirrhosis is subjected to controversial results. The aim of this work was to clarify this influence in a large cohort of prospectively followed-up cirrhotic patients classified according to the cause of their liver disease.

Methods: Three hundred one consecutive cirrhotic patients (162 alcoholics and 139 HCV-infected patients) were included at time of diagnosis of cirrhosis and followed-up. Liver iron overload on initial biopsy according to modified Deugnier's score and C282Y/H63D HFE gene mutations were assessed.

Results: In patients with alcoholic cirrhosis (mean iron score, 2.0 +/- 3.0; mean time of follow-up, 66.1 +/- 45.1 months), 40 (24.6%) developed HCC. Thirteen (8.02%) were heterozygotes for C282Y HFE gene mutation and had higher hepatic iron scores (3.6 +/- 3.8 vs 1.9 +/- 2.8, respectively, P = .05). In univariate analysis, liver iron overload as a continuous variable (HR, 1.23 [1.13-1.34], P < .001) or in binary coding with an optimal threshold of iron score >/=2.0 (HR, 4.1 [2.1-7.3], P < .0001) and C282Y mutation carriage (HR, 2.7 [1.2-6.3], P = .01) were risk factors for HCC. In multivariate analysis, liver iron and C282Y mutation carriage remained independent risk factors for HCC. In patients with HCV-related cirrhosis (C282Y mutation carriage, 17 [12.23%]; mean liver iron score, 0.9 +/- 1.9; mean time of follow-up, 85.5 +/- 42.1 months; HCC, 63 [45.32%] patients), C282Y mutation carriage and liver iron were not associated with HCC occurrence.

Conclusions: Liver iron overload and C282Y mutation are associated with a higher risk of HCC in patients with alcoholic but not HCV-related cirrhosis.
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http://dx.doi.org/10.1053/j.gastro.2007.10.038DOI Listing
January 2008

MECP2 gene mutations in non-syndromic X-linked mental retardation: phenotype-genotype correlation.

Am J Med Genet A 2003 Dec;123A(2):129-39

Service de Génétique, CHU Bretomeau, INSERM U316, 2 boulevard Tonnellé, 37044 Tours cedex, France.

Non-syndromic X-linked mental retardation (MRX) is a frequent cause of inherited mental retardation. It is a heterogeneous condition in which the first 12 genes discovered to date explain no more than 15% of the MRX situations ascertained by recurrence in multiplex families. In Rett syndrome (RTT), an X-linked dominant condition mostly sporadic and usually lethal in males, most affected females have been shown to be mutated in the Methyl-CpG binding protein 2 gene (MECP2) that maps at Xq28. Some mentally retarded males related to RTT females carry the same mutation. Several MRX families mapping to Xq28 were subsequently tested for MECP2 and a causative mutation was discovered in three families, suggesting that it could be one of the main genes involved in MRX. We report here the corresponding phenotypes in these three families of increasing severity. In family 1, an in-frame deletion DeltaP387-M466 was found in the 3' region. The patients had severe to mild non-progressive MR, with better motor skills than verbal abilities. In family 2, an Arg to Trp substitution (R167W) was found between the transcription repression domain (TRD) and the methyl binding domain (MBD). The patients had brisk reflexes and essential tremor with mild and non-progressive MR, poor motor co-ordination and written language difficulties. In the third family (MRX16), a Glu to Gly substitution (E137G) was found in the MBD. The patients had manifestations similar to those of family 2, but MR was mild to moderate, speech articulation was poor and some had verbal stereotypies. Regression of language skills was suspected in three patients. Phenotype-genotype correlation could thus be suspected and is discussed in these three families.
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http://dx.doi.org/10.1002/ajmg.a.20247DOI Listing
December 2003

Loss of parental-specific methylation at the IGF2 locus in human hepatocellular carcinoma.

J Pathol 2003 Nov;201(3):473-9

GDPM-Institut Cochin-INSERM-CNRS-Université Paris V-CHU Cochin, 24 Rue du Faubourg Saint-Jacques, 75014 Paris, France.

Significant production of the growth factor IGF2 has been reported in human hepatocellular carcinomas (HCCs). Disturbances associated with changes in methylation at this locus or affecting the 11p15.5 imprinting domain as a whole can be postulated in HCCs. In the present study, the methylation status of differentially methylated regions of the imprinted genes TSSC5, LIT1, and IGF2, which span the 11p15 domain, was analysed in 71 liver tissues from virus-associated and non-virus-associated HCCs compared with six normal liver tissues. Altered methylation of TSSC5 and LIT1 was observed in only 6% and 8% of HCCs, respectively, compared with 89% at the IGF2 locus, suggesting that these loci were not concomitantly dysregulated. These observations suggest that loss of parental-specific methylation at the IGF2 locus may be specifically associated with HCC, whether virus-associated or non-virus-associated, and arising in cirrhotic or non-cirrhotic livers.
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http://dx.doi.org/10.1002/path.1477DOI Listing
November 2003

In vitro follicular growth affects oocyte imprinting establishment in mice.

Eur J Hum Genet 2003 Jul;11(7):493-6

GDPM, Institut Cochin, INSERM, CNRS-Université Paris V and CHU Cochin, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France.

In vitro folliculogenesis of cryopreserved ovarian tissue could be an effective method for insuring fertility for patients who receive gonadotoxic treatment. Although several culture systems have been described for growing female gametes in vitro, the production of competent oocytes for further development remains a considerable challenge. The purpose of our study was to determine whether maternal primary imprinting progresses normally during mouse oocyte growth in vitro. We analysed the DNA methylation status of differentially methylated regions of the imprinted genes H19, Mest/Peg1 and Igf2R using fully grown germinal vesicle-stage oocytes (fg oocytes) produced by in vitro folliculogenesis from early preantral follicles. When compared to fg oocytes removal from control females, we observed after in vitro development, a loss of methylation at the Igf2R locus in six out of seven independent experiments and Mest/Peg1 locus (one out of seven), and a gain of methylation at the H19 locus (one out of seven). These results provide insight into the dysregulation of the process of primary imprinting during oocyte growth in vitro and highlight the need for effective new biomarkers to identify complete nuclear reprogramming competence after in vitro folliculogenesis.
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http://dx.doi.org/10.1038/sj.ejhg.5200990DOI Listing
July 2003

Active caspase-8 translocates into the nucleus of apoptotic cells to inactivate poly(ADP-ribose) polymerase-2.

J Biol Chem 2002 Sep 13;277(37):34217-22. Epub 2002 Jun 13.

INSERM U 421, Université Paris Val-de-Marne, 8 rue du General Sarrail, F-94010 Créteil cedex, France.

Caspase-8 is the prototypic initiator of the death domain receptor pathway of apoptosis. Here, we report that caspase-8 not only triggers and amplifies the apoptotic process at cytoplasmic sites but can also act as an executioner at nuclear levels. In a murine model of acute ischemia, caspase-8 is relocated into the nucleus of apoptotic neurons, where it cleaves PARP-2, a member of the poly(ADP-ribose) polymerase family involved in DNA repair. As indicated by site-directed mutagenesis, PARP-2 cleavage occurs preferentially at the LQMD sequence mapped between the DNA binding and the catalytic domains of the protein. This is close to the cleavage sequence found in Bid, the cytoplasmic target of caspase-8. Activity assays confirm that cleavage of PARP-2 results in inactivation of its poly(ADP-ribosylation) property, proportional to the efficiency of the cleavage. Our findings add to the complexity of proteolytic caspase networks by demonstrating that caspase-8 is in turn an initiator, amplifier, and effector caspase.
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http://dx.doi.org/10.1074/jbc.M203941200DOI Listing
September 2002

ARX, a novel Prd-class-homeobox gene highly expressed in the telencephalon, is mutated in X-linked mental retardation.

Hum Mol Genet 2002 Apr;11(8):981-91

Institut Cochin - CHU Cochin Port-Royal, 75014 Paris, France.

Investigation of a critical region for an X-linked mental retardation (XLMR) locus led us to identify a novel Aristaless related homeobox gene (ARX ). Inherited and de novo ARX mutations, including missense mutations and in frame duplications/insertions leading to expansions of polyalanine tracts in ARX, were found in nine familial and one sporadic case of MR. In contrast to other genes involved in XLMR, ARX expression is specific to the telencephalon and ventral thalamus. Notably there is an absence of expression in the cerebellum throughout development and also in adult. The absence of detectable brain malformations in patients suggests that ARX may have an essential role, in mature neurons, required for the development of cognitive abilities.
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http://dx.doi.org/10.1093/hmg/11.8.981DOI Listing
April 2002