Publications by authors named "Mathilde Varret"

Progressive airflow obstruction and chronic lung inflammation are hallmarks of chronic obstructive pulmonary disease (COPD). Prostaglandin E2 (PGE), synthesized by the cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1), acts as a lipid mediator with bronchodilatory effects mediated by the EP4 receptor. Altered expression and function of COX-2, mPGES-1, PGE and EP receptors may contribute to the pathophysiology of COPD.

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Article Synopsis
  • PCSK9 is crucial for regulating LDL-cholesterol and certain variants, like p.Ser127Arg, lead to higher cholesterol levels and are mainly found in France, with few in South Africa and Norway due to a common ancestor effect.
  • The study analyzed 14 p.Ser127Arg carriers from eight families and compared them with other variants to understand their genetic background and health impact.
  • Results indicated that the common ancestor lived about 775 years ago, and carriers of p.Ser127Arg had significantly higher LDL-C levels, suggesting it may have a stronger effect on cholesterol levels compared to other mutations.
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Background: The role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in dyslipidemia may go beyond its immediate effects on low-density lipoprotein receptor (LDL-R) activity.

Objective: This study aimed to assess PCSK9-derived alterations of high-density lipoprotein (HDL) physiology, which bear a potential to contribute to cardiovascular risk profile.

Methods: HDL was isolated from 33 patients with familial autosomal dominant hypercholesterolemia (FH), including those carrying PCSK9 gain-of-function (GOF) genetic variants (FH-PCSK9, n = 11), together with two groups of dyslipidemic patients employed as controls and carrying genetic variants in the LDL-R not treated (ntFH-LDLR, n = 11) and treated (tFH-LDLR, n = 11) with statins, and 11 normolipidemic controls.

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Background: Autosomal dominant hypercholesterolemia (ADH) is due to deleterious variants in , , or genes. Double heterozygote for these genes induces a more severe phenotype. More recently, a new causative variant of heterozygous ADH was identified in .

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Article Synopsis
  • Familial chylomicronemia syndrome is a rare genetic disorder marked by high plasma triglyceride levels and symptoms like abdominal pain, pancreatitis, and skin lesions due to accumulated chylomicrons.
  • A study on a consanguineous Syrian family in Lebanon identified a specific gene mutation (p.(Val227Phe)) linked to the syndrome in two affected children, and interestingly showed significant differences in PCSK9 levels among family members based on their genetic status.
  • This case emphasizes the risks of consanguineous marriages leading to genetic disorders and the importance of early diagnosis and dietary management to avoid serious health issues associated with the syndrome.
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In adults, elevated levels of circulating Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) have been associated with increased Low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and worse cardiovascular outcomes. However, few studies analyzed the relation between PCSK9 and lipid parameters in pediatric populations. The aim of our study is to evaluate the distribution and the correlation of serum PCSK9 levels with lipid parameters in a sample of Lebanese school children.

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Primary hypercholesterolemia is characterized by elevated LDL-cholesterol (LDL-C) levels isolated in autosomal dominant hypercholesterolemia (ADH) or associated with elevated triglyceride levels in familial combined hyperlipidemia (FCHL). Rare variants are known in ADH and FCHL. We explored the molecular spectrum in a French ADH/FCHL cohort of 5743 unrelated probands.

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Article Synopsis
  • Autosomal Dominant Hypercholesterolemia (ADH) is a genetic condition linked to mutations in specific genes, and the study focused on identifying new candidate genes in a French family with varying ADH risk.
  • Researchers used advanced genetic techniques to find multiple mutations in known and unknown genes, discovering a set of variants connected with the ADH trait among patients.
  • Despite identifying several genetic variants, the findings indicate that no single variant causes elevated LDL cholesterol; rather, a combination of these variants seems necessary to express the ADH phenotype.
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Lipoprotein(a) is an apolipoprotein B100-containing low-density lipoprotein-like particle that is rich in cholesterol, and is associated with a second major protein, apolipoprotein(a). Apolipoprotein(a) possesses structural similarity to plasminogen but lacks fibrinolytic activity. As a consequence of its composite structure, lipoprotein(a) may: (1) elicit a prothrombotic/antifibrinolytic action favouring clot stability; and (2) enhance atherosclerosis progression via its propensity for retention in the arterial intima, with deposition of its cholesterol load at sites of plaque formation.

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Background: The LDLR (low-density lipoprotein receptor) in the liver is the major determinant of LDL-cholesterol levels in human plasma. The discovery of genes that regulate the activity of LDLR helps to identify pathomechanisms of hypercholesterolemia and novel therapeutic targets against atherosclerotic cardiovascular disease.

Methods: We performed a genome-wide RNA interference screen for genes limiting the uptake of fluorescent LDL into Huh-7 hepatocarcinoma cells.

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Familial hypobetalipoproteinemia (FHBL) is a codominant genetic disorder characterized by reduced plasma levels of low-density lipoprotein cholesterol and apolipoprotein B. To our knowledge, no study on FHBL in Lebanon and the Middle East region has been reported. Therefore, we conducted genetic studies in unrelated families and probands of Lebanese origin presenting with FHBL, in order to identify the causes of this disease.

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Background And Purpose: Post-stroke cognitive impairment (PSCI) has become a major public health issue, as a leading cause of dementia. The inflammation that develops soon after cerebral artery occlusion and may persist for weeks or months after stroke is a key component of PSCI. Our aim was to take advantage of the immunomodulatory properties of peripheral blood mononuclear cells (PB-MNC) stimulated with ephrin-B2/fc (PB-MNC) for preventing PSCI.

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Apolipoprotein E (apoE) is a major apolipoprotein involved in lipoprotein metabolism. It is a polymorphic protein and different isoforms are associated with variations in lipid and lipoprotein levels and thus cardiovascular risk. The isoform apoE4 is associated with an increase in LDL-cholesterol levels and thus a higher cardiovascular risk compared to apoE3.

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We hypothesized that polymorphisms of genes involved in the prostaglandin pathway could be associated with COPD. In this study we explored the involvement of genetic polymorphisms in PTGS2, PTGER2 and PTGER4 genes in the development and severity of COPD and their effects on plasma concentrations of inflammatory/oxidative stress markers. We identified genotypes of PTGS2, PTGER2 and PTGER4 SNPs in a Tunisian cohort including COPD patients (n = 138) and control subjects (n = 216) using PCR-RFLP and PCR TaqMan.

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Purpose: Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening disease with often unrecognized inherited forms. We sought to identify novel pathogenic variants associated with autosomal dominant inheritance of TAAD.

Methods: We analyzed exome sequencing data from 35 French TAAD families and performed next-generation sequencing capture panel of genes in 1114 unrelated TAAD patients.

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Background: Abetalipoproteinemia, a recessive disease resulting from deleterious variants in MTTP (microsomal triglyceride transfer protein), is characterized by undetectable concentrations of apolipoprotein B, extremely low levels of low-density lipoprotein cholesterol in the plasma, and a total inability to export apolipoprotein B-containing lipoproteins from both the intestine and the liver.

Objective: To study lipid absorption after a fat load and liver function in 7 heterozygous relatives from 2 abetalipoproteinemic families, 1 previously unreported.

Results: Both patients are compound heterozygotes for p.

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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.

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Article Synopsis
  • The study focuses on patients with heterozygous familial hypercholesterolemia (HeFH) in France, highlighting the high rate of recurrent cardiovascular events among them.
  • It involved 781 patients who already had at least one cardiovascular event, with findings showing that 37% experienced additional events, often occurring years after the initial incident.
  • The results emphasize the importance of early detection and treatment with statins to prevent further cardiovascular issues, and suggest the need for broader access to advanced treatments like PCSK9 inhibitors.
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Autosomal dominant hypercholesterolemia (ADH) is characterized by elevated LDL-C levels leading to coronary heart disease. Four genes are implicated in ADH: LDLR, APOB, PCSK9 and APOE. Our aim was to identify new mutations in known genes, or in new genes implicated in ADH.

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Familial hypercholesterolemia (FH) is caused by mutations in LDLR (low-density lipoprotein receptor), APOB (apolipoprotein B), PCSK9 (proprotein convertase subtilisin/kexin type 9), or APOE (apolipoprotein E) genes in approximately 80% of the cases. Polygenic forms of hypercholesterolemia may be present among patients clinically diagnosed with FH but with no identified mutation (FH mutation-negative (FH/M-)). To address whether polygenic forms may explain phenocopies in FH families, we calculated a 6-single-nucleotide polymorphism (SNP) genetic risk score (GRS) in all members from five French FH families where a mutation was identified (FH/M+) as well as some phenocopies (FH/M-).

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Article Synopsis
  • - The study aimed to explore the link between plasma PCSK9 levels and cardiovascular events in patients with type 2 diabetes, focusing on data from two large cohorts: DIABHYCAR and SURDIAGENE.
  • - Findings indicated that higher PCSK9 levels were associated with increased risk of major cardiovascular events, including myocardial infarction and stroke in the DIABHYCAR cohort, while the SURDIAGENE cohort showed no significant association, especially among high-risk patients on treatment.
  • - The results suggest that the relationship between PCSK9 and cardiovascular events varies based on patient risk levels and treatment types, indicating a need for further research to clarify these inconsistencies.
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The identification by Abifadel et al. in 2003 of the first mutations of PCSK9 was the major breakthrough in the cholesterol field that led to a new therapeutic target. This discovery paved the way to new lipid lowering drugs reducing LDL-cholesterol levels through the inhibition of PCSK9.

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