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International audience; Contexte : L' hypercholestérolémie familiale (HF) est la maladie génétique la plus courante associée à un risque élevé de maladie cardiovasculaire athéroscléreuse prématurée attribuable à l'augmentation des taux de cholestérol LDL (LDL-C) dès la naissance. L'HF est à la fois sous-diagnostiquée et sous-traitée.Objectif : Nous décrivons les caractéristiques cliniques, biologiques et génétiques de 147 patients en France atteints d'HF clinique (dont un groupe de 26 sujets âgés de < 20 ans) ; nous explorons la meilleure façon de détecter les patients atteints d'HF monogénique.Méthodes : Nous avons examiné rétrospectivement toutes les données disponibles sur les patients subissant des tests génétiques pour l'HF de 2009 à 2019. Les diagnostics d'HF étaient basés sur les scores des adultes du Dutch Lipid Clinics Network (DLCN) et sur les taux élevés de LDL-C chez les sujets de moins de 20 ans. . Nous avons évalué le statut LDLR, APOB et PCSK9.Résultats : Les mutations des adultes (chez 25,6 % de tous les adultes) étaient associées à des scores DLCN indiquant "FH possible", "FH probable et "FH définitive" à des taux de 4 %, 16 % et 53 %, respectivement. les aires sous les courbes ROC du score DLCN et du taux maximal de LDL-C ne différaient pas (p = 0,32).Nous avons constaté que le groupe pédiatrique présentait davantage d'étiologies monogéniques (77 %, augmentant à 91 % lorsqu'un taux élevé de LDL-C était associée à des antécédents familiaux d'hypercholestérolémie et/ou de maladie coronarienne prématurée).Conclusion : Le diagnostic de l'HF monogénique peut être optimisé par le dépistage des enfants en fonction de leur taux de LDL-C, associé à un dépistage en cascade inverse des proches lorsque les enfants servent de cas index.

Potential discrepancies between laboratory and estimated (from Continuous Glucose Monitoring (CGM)) glycated hemoglobin (HbA1c) have been reported by diabetologists. CGM devices produce an eA1c derived from average glucose and correlated with Time-in-Range (TIR, %) which is the relative time spent in a range of normal glycaemia. Through a case report, we studied the potential causes for these discrepancies. CGM devices estimate eA1c during the lifespan of the sensor, that is replaced every 14 days and HbA1c is a retrospective data of exposure to hyperglycemia over 8 to 12 weeks. In our case report, the patient had a poor glycemic control resulting in 9% eA1c compared to 7,4% HbA1c got by delocalized immune-assay (Siemens DCA-Vantage®), confirmed at 7,7% by HPLC (Variant II Turbo). On top of the CGM data, an increased labile A1c (LA1c) fraction was found on the patient's HbA1c HPLC profile, both in favor of a recently altered glycemic control. Thus, recent and/or substantial variations in glycemic control will increase the gap between HbA1c and eA1c, being a potential source of therapeutic errors. The differences of those markers, particularly the time window during which it is estimated, make them hardly comparable. As the use of CGM is becoming widespread, it is important to understand and harness its data and biomarkers.

The French Society of Clinical Biology (SFBC) set up a working group “Biochemical markers of Covid-19” whose main objective is to review, analyse and monitor biological prescriptions according to the patient’s care path. This study covers all public and private sectors of medical biology in metropolitan France and overseas and extends to the French-speaking world. We present a summary of feedbacks after 2 years of the pandemic. At the early stage of Covid-19, with regard to the regions surveyed, a common symptomatology with local zoonosis (dengue fever, zika, malaria, leptospirosis, etc.) complicates the diagnosis of Covid-19. At a more advanced stage, it is a question of managing an influx of patients suffering from acute respiratory distress syndrome. In this case, the biology is then simpler and delocalized medical biology devices have proven their effectiveness. As a result, ICU clinicians can better manage the frequent comorbidities encountered in these regions: obesity, diabetes, chronic renal failure, cardiovascular diseases.La Société française de biologie clinique (SFBC) a mis en place un groupe de travail « Marqueurs biochimiques de Covid-19 » dont l’objectif principal est de revoir, d’analyser et de suivre les prescriptions biologiques en fonction du parcours de soins du patient. Cette étude couvre tous les secteurs publics et privés de la biologie médicale en métropole et en Outre-mer et s’étend à la Francophonie. Nous présentons une synthèse des retours d’expériences après 2 ans de pandémie. Au stade précoce de la Covid-19, pour les régions interrogées, une symptomatologie commune avec des zoonoses locales (dengue, zika, paludisme, leptospirose…) complique le diagnostic de la Covid-19. À un stade plus avancé, il s’agit de gérer un afflux de patients atteints de syndrome de détresse respiratoire aiguë. La biologie est alors plus simple, et les dispositifs de biologie médicale délocalisée ont prouvé leur efficacité. De ce fait, les réanimateurs peuvent mieux gérer les comorbidités fréquentes rencontrées dans ces régions : obésité, diabète, insuffisance rénale chronique ou maladies cardiovasculaires.

The French society of clinical biology "Biochemical markers of COVID-19" has set up a working group with the primary aim of reviewing, analyzing and monitoring the evolution of biological prescriptions according to the patient's care path and to look for markers of progression and severity of the disease. This study covers all public and private sectors of medical biology located in metropolitan and overseas France and also extends to the French-speaking world. This article presents the testimonies and data obtained for the "Overseas and French-speaking countries" sub-working group made up of 45 volunteer correspondents, located in 20 regions of the world. In view of the delayed spread of the SARS-CoV-2 virus, the overseas regions and the French-speaking regions have benefited from feedback from the first territories confronted with COVID-19. Thus, the entry of the virus or its spread in epidemic form could be avoided, thanks to the rapid closure of borders. The overseas territories depend very strongly on air and/or sea links with the metropolis or with the neighboring continent. The isolation of these countries is responsible for reagent supply difficulties and has necessitated emergency orders and the establishment of stocks lasting several months, in order to avoid shortages and maintain adequate patient care. In addition, in countries located in tropical or intertropical zones, the diagnosis of COVID-19 is complicated by the presence of various zoonoses (dengue, Zika, malaria, leptospirosis, etc.).

The SARS-CoV-2 virus is responsible for an epidemic disease called COVID-19, which was initially evidenced in Wuhan, China, and spread very rapidly in China and around the world. In France, the first isolated case seems now to be reported in December 2019, stage 3 of the COVID-19 epidemic was triggered on March 14(th), the start of the planned containment exit from May 11(th). Healthcare services have faced a large influx of patients who may be beyond their capacity to receive and care, particularly in the Large-East and Ile-de-France regions. Some patients show an evolution of the disease never observed before with other coronaviruses and develop in a few days a very important inflammatory reaction, which can lead to death of patients. A working group of the French Society of Clinical Biology (SFBC) was set up with the objective of providing updated information on the current status of the biological prescriptions (focusing on biochemistry ones) and their evolution during the epidemic, and of analyzing the biological parameters associated with comorbidities and patient evolution in order to link biological results with medical events. The expanded working group covers all sectors of medical biology in France and extends to the French-speaking world: hospital sectors (CHU and CH, Army Training Hospitals) and the private sector opening a field of view on the biological situation in establishments for dependent elderly, social establishments and clinical medical institutions. The purpose of this article is the presentation of this working group and its immediate and future actions., Le virus SARS-CoV-2 est responsable d’une maladie épidémique dénommée COVID-19 initialement mise en évidence à Wuhan (Chine) et qui s’est propagée très rapidement en Chine puis dans le monde entier. En France, le premier cas isolé semble être signalé dès la fin du mois de décembre2019, le stade 3 de l’épidémie a été déclenché le 14 mars 2020 et la sortie progressive du confinement est prévue à partir du 11 mai 2020. Les services de soins ont fait face à un afflux massif de patients pouvant déborder leurs capacités d’accueil et de prise en charge, notamment dans les régions Grand-Est et Ile-de-France. Certains patients présentent une évolution de la maladie encore jamais observée avec les coronavirus et développent en quelques jours une réaction inflammatoire très importante, pouvant mener au décès. Un groupe de travail de la Société française de biologie clinique (SFBC) s’est constitué, ayant pour objectif de faire le point sur les prescriptions biologiques et leur évolution au cours de l’épidémie, d’analyser les paramètres biologiques, avec un focus biochimique, associés aux comorbidités et à l’évolution du patient, dans le but de relier les résultats biologiques avec des évènements du parcours de soins du patient. Ce groupe de travail recouvre tous les secteurs publics (CHU, CH, Hôpitaux d’instruction des armées) et privés de la biologie médicale en France métropolitaine et ultra-marine ; il s’étend également à la francophonie. Il permet une vision large sur la situation biologique en milieu hospitalier, établissements d’hébergements de personnes âgées dépendantes (Ehpad), établissements médicaux sociaux (EMS) et en cliniques. Le but de cet article est la présentation de ce groupe de travail et ses actions immédiates et à venir.

Objectives Subarachnoid haemorrhage (SAH) is characterised by 25% of mortality or induces long-term care. It needs immediate diagnosis with computed tomography (CT) scan. For the inconclusive CT scans, the detection of haem pigments can be performed in the cerebrospinal fluid (CSF). The reference method is spectrophotometry but it requires a large volume of CSF, and specific equipment. Sometimes, urine test strips are used as an alternative method for haem pigments detection. However, this method needs validation in SAH context. The aim of the study was to compare the performance of Multistix® urine test strips for haem pigments detection to the reference spectrophotometry and the final clinical SAH diagnosis. Methods We collected 136 CSFs sampled for suspected SAH. We detected haem pigments with urine test strips and spectrophotometry and compared performances for 100 samples. Results Urine tests strips displayed a high sensitivity (0.97) as compared to the reference spectrophotometry for haem pigments detection. Interestingly, absence of haem pigments fully correlated with absence of SAH. Conclusions Negative Multistix® urine test strips could help to exclude SAH diagnosis in combination with clinical data when a spectrophotometer is not available, or as a bedside diagnosis test.

International audience; Obesity predisposes to an increased risk of nonalcoholic fatty liver disease (NAFLD). Hepatic steatosis is the key pathological feature of NAFLD and has emerged as a metabolic disorder in which innate and adaptive arms of the immune response play a central role in disease pathogenesis. Recent studies have revealed unexpected relationships between CD40 signaling and hepatic steatosis in high fat diet rodent models. CD154, the ligand of CD40, is a mediator of inflammation and controls several critical events of innate and adaptive immune responses. In the light of these reports, we discuss potential links between CD40 signaling and hepatic steatosis in NAFLD.

International audience; Background & aims: Blond orange juice is the most consumed fruit juice in the world. It is a source of hesperidin, a bioavailable flavonoid reported to exhibit potential vascular protective actions. However, the specific impact on vascular function of Citrus phytomicronutrients, is unknown. For the first time, we investigated the effects of blond orange juice compared with a control beverage mimicking the composition of orange juice (including Vitamin C but no phytomicronutrients), on antioxidant markers, cardiovascular risk factors and endothelial function. Methods: Twenty five male volunteers with two cardiovascular risk factors (age over 50 years and LDL-cholesterol between 130 and 190 mg/L) were enrolled in a randomized cross-over study. They received 3 times daily 200 mL of either blond orange juice or control beverage for 4 weeks, spaced by a 5-week wash-out. Endothelial function (flow mediated dilatation and plasma markers), oxidative status, lipid profile and inflammatory markers were assessed. Results: Daily intakes of orange juice significantly led to a marked antioxidant effect which was correlated to hesperetin plasma levels and related with a decrease in reactive oxygen species. A tendency towards reduction of endothelial dysfunction and modest increase in plasma apoA-I concentration were also observed. This allows further experiments demonstrating the specific effect of phytomicronutrients from orange juice. Conclusions: These findings suggest that daily intake of nutritionally relevant dose of blond orange juice may contribute for a significant antioxidant effect through the phytochemicals contained in. Orange juice may be associated to other healthy foods to achieve a significant effect on the vascular function. This study is recorded in ClinicalTrials.com as NCT00539916. (C) 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism.

Inflammation and lipid metabolism pathways are linked, and deregulation of this interface may be critical in hepatic steatosis. The importance of the dialog between inflammatory signaling pathways and the unfolded protein response (UPR) in metabolism has been underlined. Herein, we studied the role of CD154, a key mediator of inflammation, in hepatic steatosis. To this end, Balb/c mice, wild-type or deficient in CD154 (CD154KO), were fed a diet rich in olive oil. In vitro, the effect of CD154 was studied on primary hepatocyte cultures and hepatocyte-derived cell lines. Results showed that CD154KO mice fed a diet rich in olive oil developed hepatic steatosis associated with reduced apolipoprotein B100 (apoB100) expression and decreased secretion of very low-density lipoproteins. This phenotype correlated with an altered UPR as assessed by reduced X-Box binding protein-1 (XBP1) messenger RNA (mRNA) splicing and reduced phosphorylation of eukaryotic initiation factor 2α. Altered UPR signaling in livers of CD154KO mice was confirmed in tunicamycin (TM) challenge experiments. Treatment of primary hepatocyte cultures and hepatocyte-derived cell lines with soluble CD154 increased XBP1 mRNA splicing in cells subjected to either oleic acid (OA) or TM treatment. Moreover, CD154 reduced the inhibition of apoB100 secretion by HepG2 cells grown in the presence of high concentrations of OA, an effect suppressed by XBP1 mRNA silencing and in HepG2 cells expressing a dominant negative form of inositol requiring ER-to-nucleus signaling protein-1. The control of the UPR by CD154 may represent one of the mechanisms involved in the pathophysiology of hepatic steatosis. Conclusion: Our study identifies CD154 as a new mediator of hepatic steatosis. (HEPATOLOGY 2010)

Carboxylic acid haptens were synthesised, for Hesperetin ( Hesp ) and Naringenin ( Nar ). They had a spacer arm (4 or 6 carbons long) on the C7 position. Haptens were coupled to bovine serum albumin. Polyclonal antibodies were generated. Enzyme-linked immunosorbent assays (ELISAs) were developed. Owing to sensitivity, one antibody for each flavanone was retained, namely anti- h4-Hesp and anti- h4-Nar . For Hesp and Nar, IC 50 of the standard curves were 1.29 pmol/well and 0.72 pmol/well, respectively. Intra-assay and inter-assay variations were 10.24% and 10.53%, respectively for Hesp and 10.03% and 10.79%, respectively for Nar . Anti- h4-Hesp was highly specific when anti-h4-Nar showed cross-reactions with liquiritigenin and eriodictyol, which were significantly reduced in heterologous assay conditions. Assays were validated by comparisons with HPLC Coularray. Measurements were done on diet, plasma and urine samples from mice fed on diets enriched with Hesp or Nar and on a range of diluted mice urine samples.

The lipolysis stimulated receptor (LSR) recognizes apolipoprotein B/E-containing lipoproteins in the presence of free fatty acids, and is thought to be involved in the clearance of triglyceride-rich lipoproteins (TRL). The distribution of LSR in mice was studied by Northern blots, quantitative PCR and immunofluorescence. In the adult, LSR mRNA was detectable in all tissues tested except muscle and heart, and was abundant in liver, lung, intestine, kidney, ovaries and testes. During embryogenesis, LSR mRNA was detectable at 7.5 days post-coitum (E7) and increased up to E17 in parallel to prothrombin, a liver marker. In adult liver, immunofluorescence experiments showed a staining at the periphery of hepatocytes as well as in fetal liver at E12 and E15. These results are in agreement with the assumption that LSR is a plasma membrane receptor involved in the clearance of lipoproteins by liver, and suggest a possible role in steroidogenic organs, lung, intestine and kidney). To explore the role of LSR in vivo ,t heLSR gene was inactivated in 129/ Ola ES cells by removing a gene segment containing exons 2–5, and 129/Ola-C57BL/6 mice bearing the deletion were produced. Although heterozygotes appeared normal, LSR homozygotes were not viable, with the exception of three males, while the total progeny of genotyped wild-type and heterozygote pups was 345. Mortality of the homozygote embryos was observed between days 12.5 and 15.5 of gestation, a time at which their liver was much smaller than that of their littermates, indicating that the expression of LSR is critical for liver and embryonic development.

International audience; BACKGROUND: This study aimed to determine the prevalence of genetic and environmental vascular risk factors in non diabetic patients with premature peripheral arterial disease, either peripheral arterial occlusive disease or thromboangiitis obliterans, the two main entities of peripheral arterial disease, and to established whether some of them are specifically associated with one or another of the premature peripheral arterial disease subgroups. METHODS AND RESULTS: This study included 113 non diabetic patients with premature peripheral arterial disease (diagnosis

Flavanones are found specifically and abundantly in citrus fruits. Their beneficial effect on vascular function is well documented. However, little is known about their cellular and molecular mechanisms of action in vascular cells. The goal of the present study was to identify the impact of flavanone metabolites on endothelial cells and decipher the underlying molecular mechanisms of action. We investigated the impact of naringenin and hesperetin metabolites at 0·5, 2 and 10 μm on monocyte adhesion to TNF-α-activated human umbilical vein endothelial cells (HUVEC) and on gene expression. Except hesperetin-7-glucuronide and naringenin-7-glucuronide (N7G), when present at 2 μm, flavanone metabolites (hesperetin-3′-sulphate, hesperetin-3′-glucuronide and naringenin-4′-glucuronide (N4′G)) significantly attenuated monocyte adhesion to TNF-α-activated HUVEC. Exposure of both monocytes and HUVEC to N4′G and N7G at 2 μm resulted in a higher inhibitory effect on monocyte adhesion. Gene expression analysis, using TaqMan Low-Density Array, revealed that flavanone metabolites modulated the expression of genes involved in atherogenesis, such as those involved in inflammation, cell adhesion and cytoskeletal organisation. In conclusion, physiologically relevant concentrations of flavanone metabolites reduce monocyte adhesion to TNF-α-stimulated endothelial cells by affecting the expression of related genes. This provides a potential explanation for the vasculoprotective effects of flavanones.

Lecithin cholesterol acyltransferase (LCAT) is a key enzyme which catalyzes the esterification of free cholesterol present in plasma lipoproteins. In order to evaluate the role of LCAT in HDL metabolism, a 6.2-kilobase (kb) fragment consisting of 0.851 and 1.134 kb of the 5'- and 3'-flanking regions, as well as the entire human LCAT gene, was utilized to develop transgenic mice. Three different transgenic mouse lines overexpressing human LCAT at plasma levels 11-, 14-, and 109-fold higher than non-transgenic mice were established. Northern blot hybridization analysis demonstrated that the injected 6.2-kb fragment contained the necessary DNA sequences to direct tissue specific expression of the human LCAT gene in mouse liver. Compared to age- and sex-matched controls, total cholesterol and HDL cholesterol levels were increased in all 3 transgenic mice lines by 124-218 and 123-194%, respectively, while plasma triglyceride concentrations remained similar to that of control animals. Fast protein liquid chromatography analysis of transgenic mouse plasma revealed marked increases in high density liposportin (HDL)-cholesteryl ester and phospholipid as well as the formation of larger size HDL. Thus, the majority of the increase in transgenic plasma cholesterol concentrations was due to accumulation of cholesteryl ester in HDL consistent with enhanced esterification of free cholesterol in mouse HDL by human LCAT. Plasma concentrations of apoA-I, apoA-II, and apoE were increased in high expressor homozygote mice who also demonstrated an accumulation of an apoE-rich HDL1. Like the mouse enzyme, human LCAT was found to be primarily associated with mouse HDL. Our studies demonstrate a high correlation between plasma LCAT activity and total as well as HDL cholesterol levels establishing that in mice LCAT modulates plasma HDL concentrations. Overexpression of LCAT in mice leads to HDL elevation as well as increased heterogeneity of the HDL lipoprotein particles, indicating that high levels of plasma LCAT activity may be associated with hyperalphalipoproteinemia and enhanced reverse cholesterol transport.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Naringin (NAR) from grapefruit has exhibited potential protective effects against atherosclerosis development However, specific mechanisms responsible for such effects are poorly understood. Thus, we aimed to investigate the antiatherogenic effects of NAR in different mouse models of hypercholesterolemia and decipher its molecular targets in the aorta using transcriptomic approach. Two mouse models of hypercholesterolemia, wild-type mice fed a high-fat/high-cholesterol diet and apolipoprotein E-deficient mice fed a semisynthetic diet, were studied. Mice were fed a respective control diets supplemented or not for 18 weeks with 0.02% of NAR, that is, nutritional supplementation. NAR supplementation reduced plaque progression only in wild-type mice fed the high-fat/high-cholesterol diet (-41%). Consistent with this protective effect, NAR reduced plasma non-high-density lipoprotein cholesterol concentrations as well as biomarkers of endothelial dysfunction. Microarray studies performed on aortas demonstrated differentially expressed genes encoding proteins involved in cell adhesion, actin cytoskeleton organization and cell division. Thus, the changes in gene expression induced by NAR could suggest a limited atherosclerosis progression by preventing immune cell adhesion and infiltration in the intima of vascular wall, as well as smooth muscle cell proliferation. Furthermore, this hypothesis was strengthened by in vitro experiments, which showed the ability of naringenin to reduce monocyte adhesion to endothelial cells and smooth muscle cell proliferation. In conclusion, this study revealed the antiatherogenic effect of NAR supplemented at a nutritionally achievable dose, specifically toward diet-induced atherosclerosis, and depicted its multitarget mode of action at the vascular level. (C) 2012 Elsevier Inc. All rights reserved.

Epidemiological and clinical studies a role for flavanones (predominately found in citrus fruits) in the prevention of cardiovascular disease. Previously, we have shown that a nutritional dose of naringin exerts anti-atherogenic properties together with non HDL-cholesterol lowering effect in a murin model of dietary-induced hypercholesterolemia (1). The goal of the present study was to explore possible molecular mechanisms of naringin at the hepatic level. To this end, we analyzed the hepatic transcriptome using a microarray approach in response to naringin supplementation (0.02%) in mice fed a high-fat high- cholesterol diet. Naringin was observed to increase hepatic lipid content (triglyceride and cholesterol) without significant liver dysfunction (ALAT and ASAT activities) or histopathological alterations. Naringin supplementation also significantly improved insulin sensitivity as evaluated by the HOMA index and nutrigenomics revealed that naringin modulated the expression of 1,766 genes. These genes encode proteins involved in different cellular processes, such as lipid metabolism, inflammation and insulin signaling. In conclusion, this study revealed that the hypolipemic and anti-atherogenic effects induced by a nutritional- level naringin supplementation in high-fat high-cholesterol diet could be related to changes in hepatic lipid metabolism and inflammatory response, revealing new in vivo targets of this flavanone.

Transfatty acids are found mainly in processed foods. It has been shown that when their intake is high, total cholesterol, LDL-cholesterol and triacylglycerols are elevated, while HDL-cholesterol decreases. To evaluate a possible effect of these compounds, even in low amounts, C57Bl/6J mice were fed for 7 weeks a diet containing 13·6 % energy as partially hydrogenated rapeseed oil-enriched diet (Trans diet). The Trans diet contained 3 % energy astrans18 : 1 fatty acid (elaidic acid). Control mice were on an isologous diet containing native rapeseed oil (Rapeseed diet) in whichtransfatty acids were undetectable. Total, free and HDL-cholesterol as well as reverse cholesterol transport did not change. However, plasma triacylglycerol and VLDL levels increased. Hepatic gene expression in the Transv.Rapeseed diet were compared using quantitative RT–PCR. The Trans diet produced a 2–3-fold elevation in mRNA of fatty acid synthase and microsomal transfer protein mRNA, explaining (at least in part) the observed increase in triacylglycerols and VLDL. In addition, mice on the Trans diet developed a deficiency in plasma vitamin E accompanied by a higher concentration of F2-isoprostanes, indicative of increased oxidative stress. The 78 kDa glucose-related protein (GRP78) mRNA expression increased 3–4-fold in liver, suggesting that a response against apoptosis was provoked by lipid peroxidation.

The lipolysis stimulated receptor (LSR) recognizes apolipoprotein B/E-containing lipoproteins in the presence of free fatty acids, and is thought to be involved in the clearance of triglyceride-rich lipoproteins (TRL). The distribution of LSR in mice was studied by Northern blots, quantitative PCR and immunofluorescence. In the adult, LSR mRNA was detectable in all tissues tested except muscle and heart, and was abundant in liver, lung, intestine, kidney, ovaries and testes. During embryogenesis, LSR mRNA was detectable at 7.5 days post-coitum (E7) and increased up to E17 in parallel to prothrombin, a liver marker. In adult liver, immunofluorescence experiments showed a staining at the periphery of hepatocytes as well as in fetal liver at E12 and E15. These results are in agreement with the assumption that LSR is a plasma membrane receptor involved in the clearance of lipoproteins by liver, and suggest a possible role in steroidogenic organs, lung, intestine and kidney). To explore the role of LSR in vivo, the LSR gene was inactivated in 129/Ola ES cells by removing a gene segment containing exons 2-5, and 129/Ola-C57BL/6 mice bearing the deletion were produced. Although heterozygotes appeared normal, LSR homozygotes were not viable, with the exception of three males, while the total progeny of genotyped wild-type and heterozygote pups was 345. Mortality of the homozygote embryos was observed between days 12.5 and 15.5 of gestation, a time at which their liver was much smaller than that of their littermates, indicating that the expression of LSR is critical for liver and embryonic development.

To investigate the molecular events controlling reverse cholesterol transport, we compared gene expression of normal mouse liver to that of mice fed a long chain (LC) omega-3 fatty acid-enriched diet. Using cDNA microarrays, we assessed expression levels of 1176 genes, and we found that D-site binding protein (DBP) was three-fold increased in mice on a LC omega-3 fatty acid-rich diet compared to controls. DBP is known to increase transcriptional level of cholesterol 7alpha-hydroxylase (C7alpha), the rate-limiting enzyme for bile acid production and cholesterol excretion, and we found that C7alpha mRNA was also up-regulated by LC omega-3 fatty acids. Moreover, liver X receptor-alpha, another transcription factor up-regulating C7alpha, was three- to four-fold increased in liver of treated mice. On the other hand, we demonstrated that bile acid and cholesterol excretion were two-fold increased. These results show that LC omega-3 fatty acids control cholesterol metabolism in mice at a new endpoint.

In humans, diets rich in fish oil (containing n-3 FA) decrease the incidence of coronary artery diseases. This is thought to be caused by the induction in liver and skeletal muscle of genes involved in lipid oxidation, and to the repression in liver and adipose tissue of genes responsible for lipogenesis. n-3 FA are known to reduce the synthesis of FA and TG in the liver, resulting in a decrease of plasma concentrations of TG-rich lipoproteins. On the other hand, little is known of a possible effect of n-3 FA on HDL metabolism. To investigate this question, female C57Bl/6J mice were fed an n-3 FA-enriched diet for 16 wk. As expected from previous studies, we found that total cholesterol, TG, and phospholipids were reduced in the plasma of treated mice. We also found that HDL-cholesterol decreased after this treatment and that the in vivo fractional catabolic rate of HDL-cholesteryl ester was significantly higher in treated mice than in control mice fed a standard diet. Consistent with these results, treated mice exhibited increased uptake of HDL-cholesteryl ester in the liver. Moreover, quantitative reverse transcriptase-PCR analysis showed a two- to threefold increase in scavenger receptor B-1 gene expression. Taken together, these results suggest that an n-3 FA-enriched diet stimulates one step in the reverse cholesterol transport in mice, probably by increasing the amount of the scavenger receptor class B-1. These effects of n-3 FA on HDL metabolism may contribute to their beneficial effects on the vasculature.

Introduction Contexte - L’histoire naturelle de la steatopathie metabolique est classiquement divisee en deux etapes, steatose simple et steato-hepatite. Les mecanismes de cette transition restent obscurs. En tentant d’eclaircir les liens entre inflammation et steatose, nous avons observe que les souris dont le gene codant pour le CD154, un acteur cle de la reaction inflammatoire, est invalide (CD154Y/-), developpent une steatose hepatique majeure lorsqu’elles sont soumises a un regime riche en lipides. Cette steatose est liee a une reduction de la secretion des VLDL par le foie et est correlee a une reduction de l’expression de l’apoB100. Hypothese - Des etudes anterieures ont rapporte que le reticulum endoplasmique (RE) est central dans la secretion des VLDL et etabli un lien entre l’expression de l’apoB100 et le stress du RE dans un contexte de surcharge lipidique. Nous avons donc etudie les relations entre CD154 et stress du RE. La reponse au stress du RE correspond a un ensemble de mecanismes visant a adapter les capacites fonctionnelles du RE. Elle se manifeste par l’« Unfolded Protein Response » (reponse UPR), qui se traduit par l’activation de voies de signalisation dont les effecteurs contribuent a adapter les fonctions du RE a une demande accrue, comme par exemple dans un contexte de regime lipidique. Notre hypothese a ete que le CD154 facilite l’adaptation du RE a un apport lipidique excessif en intervenant sur la reponse UPR. Resultats In vivo , nous avons observe l’augmentation de l’expression des marqueurs de la reponse UPR chez les animaux sauvages mais pas chez les animaux CD154Y/- en reponse a un regime riche en lipides ou a un inducteur du stress du RE, la tunicamycine. La sensibilite hepatique a ce toxique est par ailleurs accrue chez les animaux CD154Y/-, soulignant le defaut d’adaptation du RE. Ces resultats demontraient le role du CD154 dans le controle de l’adaptation du RE. In vitro , nous avons etudie le mode d’action du CD154 sur des lignees cellulaires derivees de tumeurs hepatiques humaines. Ces lignees expriment le CD40, le recepteur du CD154. En presence de tunicamycine, le CD154 augmente la reponse UPR et la viabilite cellulaire. Conclusion Nous avons montre que les voies de signalisation activees par le CD154 interagissent avec la reponse UPR pour augmenter la capacite d’adaptation des hepatocytes dans un contexte de stress metabolique. Le controle de l’homeostasie du RE par le CD154 est un mecanisme permettant d’etablir un lien entre CD154 et steatose hepatique. Nos resultats suggerent que le CD154 est un acteur important dans la progression de la steatopathie metabolique. Remerciements, financements, autres Travail soutenu par l’Association francaise pour l’etude du foie et la Societe Echosens SA.