Estimation of glomerular filtration rate in children: interest of FAS formula / Estimation du débit de filtration glomérulaire de l'enfant : intérêt de la formule FAS

The recommended equation to estimate the value of glomerular filtration rate (eGFR) among children is Schwartz equation updated in 2009. However, it is few frequently used because involves height, a factor rarely documented for laboratories, especially hospital laboratories. The FAS (Full Aged Spectrum) formula developed by a European group, allows to get away from this factor. We compared CKD-EPI (Chronic Kidney Disease-EPIdemiology collaboration) and FAS formulas to Schwartz equation to estimate GFR in children. We realized a retrospective study included 1.668 children between 2 and 14 years old, whose serum creatinine had been measured during their hospitalization stay. We showed that FAS formula is correlated to Schwartz (r = 0.88), with a mean underestimation of eGFR at 6.2% versus CKD-EPI which has a correlation coefficient equal to 0.45 and overestimates eGFR to approximatively 42.0% compared to Schwartz formula. Furthermore, concordance at 30% is 99% with FAS whereas it's only 35% with CKD-EPI. Thus, we recommend using the FAS formula to estimate GFR in children between 2 and 14 years old when their height is not available.

L'équation recommandée pour estimer le débit de filtration glomérulaire (DFG) chez l'enfant est la formule de Schwartz mise à jour en 2009. Cependant, celle-ci n'est pas toujours utilisée en routine, car elle fait intervenir la taille, un paramètre auquel les laboratoires, notamment hospitaliers, n'ont pas facilement accès. La formule FAS (Full Aged Spectrum), mise au point par un groupe européen, permet de s'affranchir de la taille de l'enfant. Nous avons comparé les résultats du DFG obtenus à partir des équations CKD-EPI (Chronic Kidney Disease-EPIdemiology collaboration) et FAS, aux valeurs obtenues avec la formule de Schwartz. Nous avons réalisé une étude rétrospective sur 1 668 enfants âgés entre 2 et 14 ans dont le dosage de la créatininémie avait été effectué durant l'hospitalisation. Nous avons montré que l'équation FAS est bien corrélée à celle de Schwartz (r = 0,88), avec une sous-estimation moyenne du DFG de 6,2 % versus CKD-EPI qui a un coefficient de corrélation égal à 0,45 et qui surestime le DFG d'environ 42 % par rapport à la formule de Schwartz. De plus, la concordance à 30 % est de 99 % pour FAS alors qu'elle n'est que de 35 % pour CKD-EPI. Ainsi, nous recommandons d'utiliser l'équation FAS pour estimer le DFG chez l'enfant entre 2 et 14 ans lorsque la taille n'est pas disponible.

Two-year clinico-biological feedback in Overseas France and French-speaking territories during Covid-19 pandemic / Retour d'expériences clinico-biologiques en Outre-mer et en Francophonie après deux années de pandémie Covid-19

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 ¼ 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.

Phenotypic and genotypic characterization of familial hypercholesterolemia in French adult and pediatric populations.

BACKGROUND: Familial hypercholesterolemia (FH) is the most common genetic disorder associated with a high risk for premature atherosclerotic cardiovascular disease attributable to increased levels of LDL-cholesterol (LDL-C) from birth. FH is both underdiagnosed and undertreated. OBJECTIVE: We describe the clinical, biological, and genetic characteristics of 147 patients in France with clinical FH (including a group of 26 subjects aged < 20 years); we explore how best to detect patients with monogenic FH. METHODS: We retrospectively reviewed all available data on patients undergoing genetic tests for FH from 2009 to 2019. FH diagnoses were based on the Dutch Lipid Clinics Network (DLCN) scores of adults, and elevated LDL-C levels in subjects < 20 years of age. We evaluated LDLR, APOB, and PCSK9 status. RESULTS: The mutations of adults (in 25.6% of all adults) were associated with DLCN scores indicating "possible FH," "probable FH, and "definitive FH" at rates of 4%, 16%, and 53%, respectively. The areas under the ROC curves of the DLCN score and the maximum LDL-C level did not differ (p = 0.32). We found that the pediatric group evidenced more monogenic etiologies (77%, increasing to 91% when an elevated LDL-C level was combined with a family history of hypercholesterolemia and/or premature coronary artery disease). CONCLUSION: Diagnosis of monogenic FH may be optimized by screening children in terms of their LDL-C levels, associated with reverse-cascade screening of relatives when the children serve as index cases.

[Biomarkers in diabetes mellitus: contributions and discrepancies of new technologies. A case report]. / Marqueurs biologiques du diabète : apports et discordances des nouvelles technologies. À propos d'un cas clinique.

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.

[Myocardial injury in coronavirus disease 19 (Covid-19): main pathophysiological mechanisms and clinical utility of cardiac biomarkers]. / Atteintes myocardiques au cours de la maladie à coronavirus 19 (Covid-19) : principaux mécanismes physiopathologiques et utilité clinique des biomarqueurs cardiaques.

Covid-19 is responsible for myocardial injury in many infected patients, which is associated with severe disease and critical illness. The mechanisms by which SARS-CoV-2 may cause myocardial damage involve direct effect of the virus in cardiac cells and indirect effect due to the clinical consequences of Covid-19. Cardiomyocytes are well known to express Angiotensin-Converting Enzyme-2 receptors (ACE-2) to facilitate the virus cell entry, which could explain the occurrence of myocarditis, functional alterations in the myocardium, and more rarely, myocardial infarction. Myocardial injury may also be secondary to systemic inflammation or coagulopathy due to complicated Covid-19. The existence of a cardio-intestinal axis with alteration of tryptophan metabolism in the small bowel leading first to colitis and then to systemic inflammation has also been evoked to explain the myocardial injury. Morphological and metabolic disturbances of the heart during the Covid-19 are associated with elevated concentrations of cardiac blood biomarkers, mainly troponins and natriuretic peptides. The determination of these biomarkers has proven to be very useful for diagnosis, prognosis, and risk stratification. Indeed, recent data demonstrated that about 20% of infected patients admitted to the hospital have elevated troponin or BNP levels, and Covid-19 patients with elevated troponin concentrations beyond the diagnostic threshold (99th percentile) were associated with a higher risk of in-hospital mortality. In conclusion, after more than a year of a unique global pandemic, it is now clearly established that myocardial injury during Covid-19 is frequent and strongly contributes to the severity of the disease. Cardiac alterations secondary to direct infection of cardiac cells by SARS-CoV-2 or to the clinical consequences of Covid-19 are associated with elevated levels of cardiac biomarkers in blood, whose measurement is crucial in clinical decision making.

[Management of a global health crisis: first COVID-19 disease feedback from Overseas and French-speaking countries medical biologists]. / Gestion d'une crise sanitaire mondiale : premiers retours d'expérience de biologistes médicaux d'Outre-mer et de francophonie face au COVID-19.

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.).

[SFBC working group "Biochemical markers of COVID-19"]. / Groupe de travail SFBC « Marqueurs biochimiques de COVID-19 ¼.

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 14th, the start of the planned containment exit from May 11th. 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.

CD40 signaling and hepatic steatosis: Unanticipated links.

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.

Marked antioxidant effect of orange juice intake and its phytomicronutrients in a preliminary randomized cross-over trial on mild hypercholesterolemic men.

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.

Novel risk factors for premature peripheral arterial occlusive disease in non-diabetic patients: a case-control study.

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 <45-year old) presenting either a peripheral arterial occlusive disease (N = 64) or a thromboangiitis obliterans (N = 49), and 241 controls matched for age and gender. Both patient groups demonstrated common traits including cigarette smoking, low physical activity, decreased levels of HDL-cholesterol, apolipoprotein A-I, pyridoxal 5'-phosphate (active form of B6 vitamin) and zinc. Premature peripheral arterial occlusive disease was characterized by the presence of a family history of peripheral arterial and carotid artery diseases (OR 2.3 and 5.8 respectively, 95% CI), high lipoprotein (a) levels above 300 mg/L (OR 2.3, 95% CI), the presence of the factor V Leiden (OR 5.1, 95% CI) and the glycoprotein Ia(807T,837T,873A) allele (OR 2.3, 95% CI). In thromboangiitis obliterans group, more patients were regular consumers of cannabis (OR 3.5, 95% CI) and higher levels in plasma copper has been shown (OR 6.5, 95% CI). CONCLUSIONS: According to our results from a non exhaustive list of study parameters, we might hypothesize for 1) a genetic basis for premature peripheral arterial occlusive disease development and 2) the prevalence of environmental factors in the development of thromboangiitis obliterans (tobacco and cannabis). Moreover, for the first time, we demonstrated that the 807T/837T/873A allele of platelet glycoprotein Ia may confer an additional risk for development of peripheral atherosclerosis in premature peripheral arterial occlusive disease.

Flavanone metabolites decrease monocyte adhesion to TNF-α-activated endothelial cells by modulating expression of atherosclerosis-related genes.

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.

Naringin, the major grapefruit flavonoid, specifically affects atherosclerosis development in diet-induced hypercholesterolemia in mice.

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.

A protective role for CD154 in hepatic steatosis in mice.

UNLABELLED: 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.

Serum free light chain immunoassay as an adjunct to serum protein electrophoresis and immunofixation electrophoresis in the detection of multiple myeloma and other B-cell malignancies.

BACKGROUND: Protein and immunofixation electrophoresis of serum and urine are established as diagnostic aids for identifying monoclonal gammopathies. However, many patient sera sent to laboratories are not accompanied by urine samples and recent reports suggest the use of serum free light chain (sFLC) analysis in combination with serum protein electrophoresis (SPE) and immunofixation electrophoresis (lFE) could eliminate the need for urinalysis. The aim of the study was to assess the utility of sFLC measurement in addition to serum protein electrophoresis in the identification of patients with B-cell malignancies. METHODS: A total of 952 serum samples were analysed by serum protein electrophoresis and those with abnormal bands were analysed by immunofixation. sFLCs were measured in a retrospective manner by automated assay. RESULTS: In our study of 952 patient sera, it was found that FLC analysis identified 23 additional cases of B-cell malignancies which were missed by SPE. CONCLUSIONS: The additional malignancies identified by sFLC analysis add support for its inclusion in the routine screening protocol for B-cell malignancies.

Low amounts of trans 18:1 fatty acids elevate plasma triacylglycerols but not cholesterol and alter the cellular defence to oxidative stress in mice.

Trans fatty 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 as trans 18:1 fatty acid (elaidic acid). Control mice were on an isologous diet containing native rapeseed oil (Rapeseed diet) in which trans fatty 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 Trans v. 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.

Distribution of the lipolysis stimulated receptor in adult and embryonic murine tissues and lethality of LSR-/- embryos at 12.5 to 14.5 days of gestation.

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.

Dietary fish oil up-regulates cholesterol 7alpha-hydroxylase mRNA in mouse liver leading to an increase in bile acid and cholesterol excretion.

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.

n-3 FA increase liver uptake of HDL-cholesterol in mice.

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.