Maternal Inheritance of Familial Hypercholesterolemia Gene Mutation Predisposes to Coronary Atherosclerosis as Assessed by Calcium Score in Adulthood.

BACKGROUND: Animal studies have demonstrated that fetal exposure to high maternal cholesterol levels during pregnancy predisposes to aortic atheroma in the offspring. In humans, little is known about the consequences of this exposure on the development of atherosclerotic cardiovascular disease later in life. We wanted to assess whether maternal/paternal inheritance of familial hypercholesterolemia (FH) gene mutation could be associated with subclinical coronary atherosclerosis. METHODS: We retrospectively included 1350 patients, followed in the French registry of FH, with a documented genetic diagnosis. We selected 556 age- and sex-matched pair of patients based on the sex of the parents who transmitted the FH gene mutation, free of coronary cardiovascular event, and with a subclinical coronary atherosclerosis evaluation assessed using coronary artery calcium (CAC) score. We performed univariate and multivariate analysis to assess the individual effect of parental inheritance of the FH gene mutation on the CAC score. RESULTS: In the whole population, patients with maternal inheritance of FH gene mutation (n=639) less frequently had a family history of premature cardiovascular events (27.7% versus 45%, P<0.0001) and were 2 years older (46.9±16.8 versus 44.7±15.9 years old, P=0.02) than those with paternal inheritance (n=711). There was no difference in the prevalence of cardiovascular events between the two groups. In the matched subgroup, maternal inheritance was significantly associated with an increase in CAC score value by 86% (95% CI, 23%-170%; P=0.003), a 1.81-fold risk of having a CAC score ≥100 Agatston units (95% CI, 1.06-3.11; P=0.03), and a 2.72-fold risk of having a CAC score ≥400 Agatston units (95% CI, 1.39-5.51; P=0.004) when compared with paternal inheritance in multivariate analysis. CONCLUSIONS: Maternal inheritance of FH gene mutation was associated with more severe subclinical coronary atherosclerosis assessed by CAC score and may be considered as a potential cardiovascular risk factor.

Additive Effect of APOE Rare Variants on the Phenotype of Familial Hypercholesterolemia.

BACKGROUND: Autosomal dominant hypercholesterolemia (ADH) is due to deleterious variants in LDLR, APOB, or PCSK9 genes. Double heterozygote for these genes induces a more severe phenotype. More recently, a new causative variant of heterozygous ADH was identified in APOE. Here we study the phenotype of 21 adult patients, double heterozygotes for rare LDLR and rare APOE variants (LDLR+APOE) in a national wide French cohort. METHODS: LDLR, APOB, PCSK9, and APOE genes were sequenced in 5743 probands addressed for ADH genotyping. The lipid profile and occurrence of premature atherosclerotic cardiovascular diseases were compared between the LDLR+APOE carriers (n=21) and the carriers of the same LDLR causative variants alone (n=22). RESULTS: The prevalence of LDLR+APOE carriers in this French ADH cohort is 0.4%. Overall, LDL (low-density lipoprotein)-cholesterol concentrations were 23% higher in LDLR+APOE patients than in LDLR patients (9.14±2.51 versus 7.43±1.59 mmol/L, P=0.0221). When only deleterious or probably deleterious variants were considered, the LDL-cholesterol concentrations were 46% higher in LDLR+APOE carriers than in LDLR carriers (10.83±3.45 versus 7.43±1.59 mmol/L, P=0.0270). Two patients exhibited a homozygous familial hypercholesterolemia phenotype (LDL-cholesterol >13 mmol/L). Premature atherosclerotic cardiovascular disease was more common in LDLR+APOE patients than in LDLR carriers (70% versus 30%, P=0.026). CONCLUSIONS: Although an incomplete penetrance should be taken into account for APOE variant classification, these results suggest an additive effect of deleterious APOE variants on ADH phenotype highlighting the relevance of APOE sequencing.

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

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.

Insights into medical students' perceptions of work culture during the COVID-19 pandemic: a mixed method study.

BACKGROUND: The COVID-19 pandemic brought about profound social changes that affected students worldwide. These changes had both psychological and economic consequences, and also led to the adoption of new teaching methods. It can also have an impact on work culture, which is the collective set of values, norms, and practices within a specific profession, shaping how individuals in that field behave, communicate, and identify with their work. The aim of the study was to examine medical students' perception of professional culture during the COVID-19 crisis when they voluntarily participated in the healthcare network established, outside of university placements, for the management of COVID patients. METHODS: A questionnaire study based on the vignette methodology was conducted among third-year medical students. Drawing from three scenarios in which students were variably engaged in crisis management, it included questions about their perceptions of the medical profession, their motivation, and their sense of belonging to the profession. RESULTS: 352 students responded to the survey. The pandemic had both a positive and a negative impact on students' perceptions of the medical profession. Cluster analysis using a k-means algorithm and principal component analysis revealed three clusters of students with different perceptions of the medical profession. The first cluster, which represented the majority of students, corresponded to a relatively positive perception of the profession that was reinforced during the pandemic. In the second cluster, students' perceptions were reinforced still further, and particular importance was attached to field experience. Students in the third cluster had the most negative perceptions, having been shaken the most by the pandemic, and they attached little importance to field experience. CONCLUSIONS: The analysis highlighted the importance of students being able to adapt and draw on a range of resources during the COVID-19 pandemic. This underscores the need for work cultures that support adaptability and coping. Further research is needed to understand its long-term effects on students' perceptions of the medical profession and to identify interventions that could support students in the aftermath of this difficult period.

The Clinical Genome Resource (ClinGen) Familial Hypercholesterolemia Variant Curation Expert Panel consensus guidelines for LDLR variant classification.

PURPOSE: In 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published consensus standardized guidelines for sequence-level variant classification in Mendelian disorders. To increase accuracy and consistency, the Clinical Genome Resource Familial Hypercholesterolemia (FH) Variant Curation Expert Panel was tasked with optimizing the existing ACMG/AMP framework for disease-specific classification in FH. In this study, we provide consensus recommendations for the most common FH-associated gene, LDLR, where >2300 unique FH-associated variants have been identified. METHODS: The multidisciplinary FH Variant Curation Expert Panel met in person and through frequent emails and conference calls to develop LDLR-specific modifications of ACMG/AMP guidelines. Through iteration, pilot testing, debate, and commentary, consensus among experts was reached. RESULTS: The consensus LDLR variant modifications to existing ACMG/AMP guidelines include (1) alteration of population frequency thresholds, (2) delineation of loss-of-function variant types, (3) functional study criteria specifications, (4) cosegregation criteria specifications, and (5) specific use and thresholds for in silico prediction tools, among others. CONCLUSION: Establishment of these guidelines as the new standard in the clinical laboratory setting will result in a more evidence-based, harmonized method for LDLR variant classification worldwide, thereby improving the care of patients with FH.

Phenotypic Differences Between Polygenic and Monogenic Hypobetalipoproteinemia.

OBJECTIVE: Primary hypobetalipoproteinemia is characterized by LDL-C (low-density lipoprotein cholesterol) concentrations below the fifth percentile. Primary hypobetalipoproteinemia mostly results from heterozygous mutations in the APOB (apolipoprotein B) and PCSK9 genes, and a polygenic origin is hypothesized in the remaining cases. Hypobetalipoproteinemia patients present an increased risk of nonalcoholic fatty liver disease and steatohepatitis. Here, we compared hepatic alterations between monogenic, polygenic, and primary hypobetalipoproteinemia of unknown cause. Approach and Results: Targeted next-generation sequencing was performed in a cohort of 111 patients with hypobetalipoproteinemia to assess monogenic and polygenic origins using an LDL-C-dedicated polygenic risk score. Forty patients (36%) had monogenic hypobetalipoproteinemia, 38 (34%) had polygenic hypobetalipoproteinemia, and 33 subjects (30%) had hypobetalipoproteinemia from an unknown cause. Patients with monogenic hypobetalipoproteinemia had lower LDL-C and apolipoprotein B plasma levels compared with those with polygenic hypobetalipoproteinemia. Liver function was assessed by hepatic ultrasonography and liver enzymes levels. Fifty-nine percent of patients with primary hypobetalipoproteinemia presented with liver steatosis, whereas 21% had increased alanine aminotransferase suggestive of liver injury. Monogenic hypobetalipoproteinemia was also associated with an increased prevalence of liver steatosis (81% versus 29%, P<0.001) and liver injury (47% versus 0%) compared with polygenic hypobetalipoproteinemia. CONCLUSIONS: This study highlights the importance of genetic diagnosis in the clinical care of primary hypobetalipoproteinemia patients. It shows for the first time that a polygenic origin of hypobetalipoproteinemia is associated with a lower risk of liver steatosis and liver injury versus monogenic hypobetalipoproteinemia. Thus, polygenic risk score is a useful tool to establish a more personalized follow-up of primary hypobetalipoproteinemia patients.

APOE Molecular Spectrum in a French Cohort with Primary Dyslipidemia.

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 APOE variants are known in ADH and FCHL. We explored the APOE molecular spectrum in a French ADH/FCHL cohort of 5743 unrelated probands. The sequencing of LDLR, PCSK9, APOB, and APOE revealed 76 carriers of a rare APOE variant, with no mutation in LDLR, PCSK9, or APOB. Among the 31 APOE variants identified here, 15 are described in ADH, 10 in FCHL, and 6 in both probands. Five were previously reported with dyslipidemia and 26 are novel, including 12 missense, 5 synonymous, 2 intronic, and 7 variants in regulatory regions. Sixteen variants were predicted as pathogenic or likely pathogenic, and their carriers had significantly lower polygenic risk scores (wPRS) than carriers of predicted benign variants. We observed no correlation between LDL-C levels and wPRS, suggesting a major effect of APOE variants. Carriers of p.Leu167del were associated with a severe phenotype. The analysis of 11 probands suggests that carriers of an APOE variant respond better to statins than carriers of a LDLR mutation. Altogether, we show that the APOE variants account for a significant contribution to ADH and FCHL.

Lessons from the impact of COVID-19 on medical educational continuity and practices.

The COVID-19 crisis necessitated abrupt transition to remote learning in medical schools. We aimed to assess the impact of COVID-19 on French undergraduate students and teachers, to identify practice changes, and to evaluate successes and areas for improvement of this remote learning experience. Data from 2 online questionnaires were analyzed with 509 participants among students and 189 among teachers from Sorbonne University. Responses to multiple choice, Likert response scale, and open-ended questions were evaluated. COVID-19 had negative impact on teaching continuity. Sixty-seven percent of students were in a dropout situation, and many suffered from psychological stress, leading to set up of a psychological support unit. Although most teachers (81%) and students (72%) had limited knowledge of digital resources, distance learning was quickly implemented, with a predominant use of Zoom. The analysis of several parameters revealed that students were significantly more satisfied than teachers by remote learning. Nevertheless, both students and teachers agreed to replace classical lectures by digital media and to promote in-person teaching in small interactive groups. This paper shares tips for faculty rapidly establishing remote learning. This comparative study of the students' and teachers' points of view underlines that new medical curricula should include more digital contents. We make recommendations regarding general university organization, equipment, and curricular development for long-term implementation of digital resources with reinforced relationships between faculty and students.

LDL apheresis as an alternate method for plasma LPS purification in healthy volunteers and dyslipidemic and septic patients.

Lipopolysaccharide (LPS) is a key player for innate immunity activation. It is therefore a prime target for sepsis treatment, as antibiotics are not sufficient to improve outcome during septic shock. An extracorporeal removal method by polymyxin (PMX) B direct hemoperfusion (PMX-DHP) is used in Japan, but recent trials failed to show a significant lowering of circulating LPS levels after PMX-DHP therapy. PMX-DHP has a direct effect on LPS molecules. However, LPS is not present in a free form in the circulation, as it is mainly carried by lipoproteins, including LDLs. Lipoproteins are critical for physiological LPS clearance, as LPSs are carried by LDLs to the liver for elimination. We hypothesized that LDL apheresis could be an alternate method for LPS removal. First, we demonstrated in vitro that LDL apheresis microbeads are almost as efficient as PMX beads to reduce LPS concentration in LPS-spiked human plasma, whereas it is not active in PBS. We found that PMX was also adsorbing lipoproteins, although less specifically. Then, we found that endogenous LPS of patients treated by LDL apheresis for familial hypercholesterolemia is also removed during their LDL apheresis sessions, with both electrostatic-based devices and filtration devices. Finally, LPS circulating in the plasma of septic shock and severe sepsis patients with gram-negative bacteremia was also removed in vitro by LDL adsorption. Overall, these results underline the importance of lipoproteins for LPS clearance, making them a prime target to study and treat endotoxemia-related conditions.

Polyvascular subclinical atherosclerosis in familial hypercholesterolemia: The role of cholesterol burden and gender.

BACKGROUND AND AIM: Heterozygous familial hypercholesterolemia (HeFH) is a genetic disease characterized by a heterogeneous phenotype. The assessment of cardiovascular (CV) risk is challenging for HeFH. Cholesterol burden (CB) allows to estimate the lifelong exposure to high levels of cholesterol. The aim of this study was to analyze the distribution of subclinical atherosclerosis and the relationship between atherosclerosis and the CB in a sample of HeFH patients, focusing on sex-related differences. METHODS AND RESULTS: 154 asymptomatic HeFH subjects underwent coronary-artery-calcium score (CACs) and Doppler ultrasound of carotid and femoral arteries. Yearly lipid profiles and HeHF history were obtained from patients' files in order to calculate total CB. Atherosclerotic burden was defined by the presence of CACs > 0 or by the presence of carotid or femoral plaque. Study population was stratified according to gender. The prevalence of CAC, carotid and femoral atherosclerosis was of 62%, 55% and 56%, respectively. Coronary district was the least involved in women, who had a higher prevalence in carotid atherosclerosis. When two vascular districts were affected, women had an increased prevalence of femoral and carotid atherosclerosis whereas men had a higher prevalence of coronary and femoral atherosclerosis. CB correlated to the presence of atherosclerosis in any of the three vascular districts with a significant increasing trend depending on the number of affected areas. CONCLUSIONS: A polyvascular atherosclerotic burden is found in asymptomatic HeFH patients. Gender differences in the territory distribution were observed. The early and lasting exposure to high cholesterol, as expressed by CB, is a major determinant of atherosclerotic burden.

Familial hypercholesterolemia: experience from France.

PURPOSE OF REVIEW: We provide an overview of molecular diagnosis for familial hypercholesterolemia in France including descriptions of the mutational spectrum, polygenic susceptibility and perspectives for improvement in familial hypercholesterolemia diagnosis. RECENT FINDINGS: Molecular testing for familial hypercholesterolemia is recommended for patients with a LDL-cholesterol level above 190 mg/dl (adults) associated with criteria related to personal and family history of hypercholesterolemia and premature cardiovascular disease. Among the 3381 index cases included with these characteristics in the French registry for familial hypercholesterolemia, 2054 underwent molecular diagnosis and 1150 (56%) were found to have mutations (93.5% in LDL Receptor (LDLR), 4.7% in apolipoprotein B and 1.8% in Proprotein convertase subtilisin/kexin type 9). A total of 416 different pathogenic variants were found in the LDLR gene. Based on gene score calculation, a polygenic origin may be suggested in 36% of nonmutated patients. Involvement of genetic counselors and education of healthcare professionals for genetics of familial hypercholesterolemia are underway with the aim of improving the efficiency of the diagnosis. SUMMARY: Genetic cascade screening for familial hypercholesterolemia is currently implemented in France with the complexity to address the diversity of its molecular cause in index cases. Optimization of patient care pathways is critical to improve both the rate of diagnosis and the management of familial hypercholesterolemia patients.

ClinVar database of global familial hypercholesterolemia-associated DNA variants.

Accurate and consistent variant classification is imperative for incorporation of rapidly developing sequencing technologies into genomic medicine for improved patient care. An essential requirement for achieving standardized and reliable variant interpretation is data sharing, facilitated by a centralized open-source database. Familial hypercholesterolemia (FH) is an exemplar of the utility of such a resource: it has a high incidence, a favorable prognosis with early intervention and treatment, and cascade screening can be offered to families if a causative variant is identified. ClinVar, an NCBI-funded resource, has become the primary repository for clinically relevant variants in Mendelian disease, including FH. Here, we present the concerted efforts made by the Clinical Genome Resource, through the FH Variant Curation Expert Panel and global FH community, to increase submission of FH-associated variants into ClinVar. Variant-level data was categorized by submitter, variant characteristics, classification method, and available supporting data. To further reform interpretation of FH-associated variants, areas for improvement in variant submissions were identified; these include a need for more detailed submissions and submission of supporting variant-level data, both retrospectively and prospectively. Collaborating to provide thorough, reliable evidence-based variant interpretation will ultimately improve the care of FH patients.

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

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.

Clinical Expression of Familial Hypercholesterolemia in Patients from France and French Canada Carrying Identical-by-Descent Pathogenic LDLR Gene Variants: A Proof-of-Concept Study.

Background: Studying patients carrying identical-by-descent (IBD) pathogenic gene variants allows us to control for the disease-causing genetic background and to more accurately document the impact of modifiers. Familial hypercholesterolemia (FH) is characterized by elevated low-density lipoprotein cholesterol (LDL-c) levels and premature atherosclerosis and is often caused by defects in the LDLR gene. There is a high prevalence of FH in French Canada as a result of a founder effect from France in the 17th century. Several FH patients currently living in French Canada (founder population) and in France (colonizing population) carry IBD FH-causing variants. The expression of FH is affected by environmental and genetic modifiers, and patients with IBD variants may present different characteristics. Methods: In this study, we compared FH clinical expression patients carrying IBD LDLR pathogenic variants living in France or Canada. Four IBD variants, namely c.259T>G p.(Trp87Gly), c.2000G>A p.(Cys667Tyr), c.682G>A p.(Glu228Lys), and c.1048C>T p.(Arg350*), were selected. Untreated plasma lipid profiles, the apolipoprotein E (APOE) genotype, cardiovascular risk factors, and the occurrence of symptomatic ASCVD were compared in 105 adult carriers (30 from France and 75 from French Canada). Results: All parameters were similar between the two populations, except for untreated total cholesterol (10.14 ± 1.89 mmol/L vs. 8.65 ± 1.84 mmol/L, p = 0.0006) and LDL-c concentrations (7.94 ± 1.86 mmol/L vs. 6.93 ± 1.78 mmol/L, p = 0.016), which were significantly higher in FH patients living in France, an observation that was revealed across all studied LDLR variants. Conclusions: This study illustrates that FH patients sharing IBD pathogenic LDLR variants that have evolved in different geographic, cultural, and socio-economic environments for hundreds of years differ in terms of cholesterol levels, highlighting the importance of better understanding the interplay between genetic and environmental modulators of FH expression.

The singular French PCSK9-p.Ser127Arg gain-of-function variant: A significant player in cholesterol levels from a 775-year-old common ancestor.

BACKGROUND AND AIMS: PCSK9 is a key regulator of LDL-cholesterol levels. PCSK9 gain of function variants (GOFVs) cause autosomal dominant hypercholesterolemia (ADH). The first described PCSK9-GOFV, p.Ser127Arg, almost exclusively reported in France, represents 67 % of the PCSK9 French GOFVs due to a founder effect. Few other carriers are reported in South Africa and Norway. This study aims to estimate when the common ancestor lived and to describe a cohort of p.Ser127Arg carriers. METHODS: Eight families and 14 p.Ser127Arg carriers were genotyped and phenotyped. Haplotypes were constructed using 11 microsatellites around PCSK9 and 6 intragenic single nucleotide polymorphisms (SNPs). To add to the biological analysis, eight additional p.Ser127Arg carriers, 12 carriers of other PCSK9-GOFVs, 93 LDLR loss of function variant (LOFV) carriers and 49 non-carriers subjects were phenotyped. RESULTS: The most common ancestor of p.Ser127Arg was estimated to have lived 775 years ago [95 % CI: 575-1075]. French Protestants exiled after the revocation of the Edict of Nantes in 1685 AD likely brought the variant to South Africa and Norway. As expected for ADH subjects, carriers of LDLR-LOFV, the p.Ser127Arg, or other PCSK9-GOFVs showed significantly higher LDL-C levels than that of the non-carriers. Interestingly, LDL-C levels are higher for LDLR-LOFVs and for the reduced secreted p.Ser127Arg than for secreted PCSK9-GOFVs, suggesting a greater effect of the p.Ser127Arg. Conversely, HDL-C was significantly lower for LDLR-LOFV and p.Ser127Arg carriers. CONCLUSIONS: This first report from a large cohort of PCSK9-p.Ser127Arg carriers provides observations suggesting a stronger hypercholesterolemic potential of the mutated pro-PCSK9 compared with the secreted mature protein. This work also provides additional data to support the association between PCSK9 and HDL metabolism, and molecular evidence that this variant appeared in France around 1248 AD (Graphical Abstract = Fig. 1).

Integrated omics approach for the identification of HDL structure-function relationships in PCSK9-related familial hypercholesterolemia.

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. Biological evaluations paralleled by proteomic, lipidomic and glycomic analyses were applied to characterize functional and compositional properties of HDL. RESULTS: Multiple deficiencies in the HDL function were identified in the FH-PCSK9 group relative to dyslipidemic FH-LDLR patients and normolipidemic controls, which involved reduced antioxidative, antiapoptotic, anti-thrombotic and anti-inflammatory activities. By contrast, cellular cholesterol efflux capacity of HDL was unchanged. In addition, multiple alterations of the proteomic, lipidomic and glycomic composition of HDL were found in the FH-PCSK9 group. Remarkably, HDLs from FH-PCSK9 patients were systematically enriched in several lysophospholipids as well as in A2G2S2 (GP13) glycan and apolipoprotein A-IV. Based on network analysis of functional and compositional data, a novel mosaic structure-function model of HDL biology involving FH was developed. CONCLUSION: Several metrics of anti-atherogenic HDL functionality are altered in FH-PCSK9 patients paralleled by distinct compositional alterations. These data provide a first-ever overview of the impact of GOF PCSK9 genetic variants on structure-function relationships in HDL.

Impact of LDL apheresis on atheroprotective reverse cholesterol transport pathway in familial hypercholesterolemia.

In familial hypercholesterolemia (FH), low HDL cholesterol (HDL-C) levels are associated with functional alterations of HDL particles that reduce their capacity to mediate the reverse cholesterol transport (RCT) pathway. The objective of this study was to evaluate the consequences of LDL apheresis on the efficacy of the RCT pathway in FH patients. LDL apheresis markedly reduced abnormal accelerated cholesteryl ester transfer protein (CETP)-mediated cholesteryl ester (CE) transfer from HDL to LDL, thus reducing their CE content. Equally, we observed a major decrease (-53%; P < 0.0001) in pre-ß1-HDL levels. The capacity of whole plasma to mediate free cholesterol efflux from human macrophages was reduced (-15%; P < 0.02) following LDL apheresis. Such reduction resulted from a marked decrease in the ABCA1-dependent efflux (-71%; P < 0.0001) in the scavenger receptor class B type I-dependent efflux (-21%; P < 0.0001) and in the ABCG1-dependent pathway (-15%; P < 0.04). However, HDL particles isolated from FH patients before and after LDL apheresis displayed a similar capacity to mediate cellular free cholesterol efflux or to deliver CE to hepatic cells. We demonstrate that rapid removal of circulating lipoprotein particles by LDL apheresis transitorily reduces RCT. However, LDL apheresis is without impact on the intrinsic ability of HDL particles to promote either cellular free cholesterol efflux from macrophages or to deliver CE to hepatic cells.

Atheroprotective reverse cholesterol transport pathway is defective in familial hypercholesterolemia.

OBJECTIVE: Low high-density lipoprotein (HDL) cholesterol levels are frequently observed in familial hypercholesterolemia (FH) and might be associated with functional alterations of HDL particles that may influence their efficaciousness in the reverse cholesterol transport pathway. METHODS AND RESULTS: We evaluated key steps of the reverse cholesterol transport, ie, cellular free cholesterol efflux, cholesteryl ester transfer protein-mediated cholesteryl ester (CE) transfer from HDL to apolipoprotein B-containing lipoproteins, and hepatic HDL-CE uptake, in patients displaying FH (n = 12) and in healthy normolipidemic control subjects (n = 12). Large HDL2 particles isolated from FH patients displayed a reduced capacity to mediate free cholesterol efflux via both scavenger receptor-BI- and ABCG1-dependent pathways. A significant inverse relationship between scavenger receptor-BI-dependent HDL2 efflux capacity and carotid intima-media thickness (r = -0.473; P = 0.0186), as well as between ABCG1-dependent HDL2 efflux capacity and carotid intima-media thickness (r = -0.485; P = 0.0212), was detected. We also observed an elevated cholesteryl ester transfer protein-mediated CE transfer from HDL2 and HDL3 particles to low-density lipoprotein and a reduced capacity of HDL particles to deliver CEs to the liver. CONCLUSIONS: We demonstrated that the centripetal movement of cholesterol from peripheral tissues, including the vessel wall, to feces is defective in FH, thereby emphasizing its atherogenicity.