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Furin, a member of the mammalian proprotein convertases family, can promote the proteolytic maturation of proproteins. It is known that furin is predominantly present in certain cell types of human atherosclerotic lesions and neointima in animal models, including vascular smooth muscle cells, endothelial cells and mononuclear inflammatory cells. Evidence suggests that furin participates in the initiation and progression of atherosclerosis through regulation of lipid and cholesterol metabolism, inflammatory response, blood pressure and the formation of atherosclerotic lesions. This review provides a panorama of the roles of furin in atherosclerosis and the insights into the prevention and treatment of atherosclerosis and cardiovascular disease.

In this review, we discuss the screening and treatment of familial hypercholesterolemia (FH), an autosomal dominant inherited disease, characterized by severely increased levels of low-density lipoprotein cholesterol (LDL-C) and increased risk for premature coronary heart disease (CHD). Genetic family based cascade screening for FH was shown to be cost-effective and a screening program with such an approach was carried out in the Netherlands from 1994 to 2014. Over 64,000 persons have participated in this program of whom 40.3% were found to carry an FH causing mutation. We will discuss the results of this screening program, as well as the scientific opportunities it has provided. Currently, statins and ezetimibe are the only registered LDL-C lowering treatment options for FH patients. Many of them do not attain the treatment goals that are recommended by treatment guidelines. In this review, we will also provide a comprehensive overview of promising new modalities that could lower LDL-C in FH patients.

Proprotein convertase subtilisin kexin type 9 (PCSK9) is a circulatory ligand that terminates the lifecycle of the low-density lipoprotein (LDL) receptor (LDLR) thus affecting plasma LDL-cholesterol (LDL-C) levels. Recent evidence shows that in addition to the straightforward mechanism of action, there are more complex interactions between PCSK9, LDLR and plasma lipoprotein levels, including: (a) the presence of both parallel and reciprocal regulation of surface LDLR and plasma PCSK9; (b) a correlation between PCSK9 and LDL-C levels dependent not only on the fact that PCSK9 removes hepatic LDLR, but also due to the fact that up to 40% of plasma PCSK9 is physically associated with LDL; and (c) an association between plasma PCSK9 production and the assembly and secretion of triglyceride-rich lipoproteins. The effect of PCSK9 on LDLR is being successfully utilized toward the development of anti-PCSK9 therapies to reduce plasma LDL-C levels. Current biochemical research has uncovered additional mechanisms of action and interacting partners for PCSK9, and this opens the way for a more thorough understanding of the regulation, metabolism, and effects of this interesting protein.

Monoclonal antibodies (mAbs) are established therapies for many conditions, including cancers, autoimmune conditions and infectious diseases. mAbs can offer benefits over conventional pharmacotherapy in terms of potency, dosing frequency and specificity for their target antigen. Mouse-derived antibodies were initially used in humans; however, patients often developed human anti-mouse antibodies, resulting in rapid antibody clearance (and a resulting loss of efficacy) and hypersensitivity reactions. Chimeric, humanized, and fully human antibodies were thus developed, with increasing amounts of human sequence, to reduce immunogenicity. Although generally well tolerated, mAbs may be associated with adverse events (AEs). Many AEs are target-related, and will be specific to the antibody target and the therapeutic area of use. However, off-target AEs, such as hypersensitivity reactions, are observed with many antibodies.Within the realm of cardiovascular medicine, new antibody-based therapies are under investigation to reduce low-density lipoprotein cholesterol (LDL-C) levels. Proprotein convertase subtilisin/kexin type 9 (PCSK9) regulates plasma LDL-C levels by increasing degradation of the LDL receptor (LDLR). Therefore, inhibition of the interaction between PCSK9 and the LDLR with mAbs targeting PCSK9 has great potential for patients with hypercholesterolaemia. Early clinical phase studies suggest these mAbs are effective and well tolerated; however, further studies are required to assess their long-term safety.

Objectives The proprotein convertase subtillisin/kexin type 9 (PCSK9) regulates cholesterol metabolism via degradation of low-density lipoprotein receptor (LDLr). Although PCSK9 is abundantly expressed in the intestine, limited data are available on its functions. The present study aims at determining whether PCSK9 plays important roles in cholesterol homeostasis and lipid transport in the gut. Methods and results Caco-2/15 cells were used allowing the exploration of the PCSK9 secretory route through the apical and basolateral compartments corresponding to intestinal lumen and serosal circulation, respectively. The output of PCSK9 occurred through the basolateral membrane, a site characterized by the location of LDLr. Co-immunoprecipitation studies indicated an association between PCSK9 and LDLr. Addition of purified recombinant wild type and D374Y gain-of function PCSK9 proteins to the basolateral medium was followed by a decrease in LDLr concomitantly with the accumulation of both forms of PCSK9. Furthermore, the latter caused a significant enhancement in cholesterol uptake also evidenced by a raised protein expression of cholesterol transporters NPC1L1 and CD36 without changes in SR-BI, ABCA1, and ABCG5/G8. Moreover, exogenous PCSK9 altered the activity of HMG-CoA reductase and acylcoenzyme A: cholesterol acyltransferase, and was able to enhance chylomicron secretion by positively modulating lipids and apolipoprotein B-48 biogenesis. Importantly, PCSK9 silencing led to opposite findings, which validate our data on the role of PCSK9 in lipid transport and metabolism. Moreover, PCSK9-mediated changes persisted despite LDLr knockdown. Conclusions These findings indicate that, in addition to its effect on LDLr, PCSK9 modulates cholesterol transport and metabolism, as well as production of apo B-containing lipoproteins in intestinal cells.

Background The identification of mutations in PCSK9 (proprotein convertase subtilisin kexin9) in autosomal dominant hypercholesterolemia (ADH), has revealed the existence of a new player in cholesterol homeostasis. PCSK9 has been shown to enhance the degradation of the LDL receptor (LDLR) at the cell surface. Gain-of-function mutations of PCSK9 induce ADH and are very rare, but their identification is crucial in studying PCSK9's role in hypercholesterolemia, its detailed trafficking pathway and its impact on the LDLR. Methods In order to identify new mutations and understand the exact mechanisms of action of mutated PCSK9, PCSK9 was sequenced in 75 ADH patients with no mutations in the LDLR or APOB genes. Functional analyses in cell culture were conducted and the impact of novel PCSK9 mutations on the quantitative and qualitative features of lipoprotein particles and on the HDL-mediated cellular cholesterol efflux was studied. Results Among these 75 ADH probands with no mutations in the LDLR or APOB genes, four gain-of-function mutations of PCSK9 were identified, of which two were novel: the p.Leu108Arg and the p.Asp35Tyr substitutions. In vitro studies of their consequences on the activity of PCSK9 on cell surface levels of LDLR showed that the p.Leu108Arg mutation clearly results in a gain-of-function, while the p.Asp35Tyr mutation created a novel Tyr-sulfation site, which may enhance the intracellular activity of PCSK9. Conclusion These data further contribute to the characterization of PCSK9 mutations and to better understanding of the impact on cholesterol metabolism of this new therapeutic target.

Background Autosomal dominant hypercholesterolemia (ADH) is commonly caused by mutations in the low-density lipoprotein (LDL) receptor gene ( LDLR ), in the apolipoprotein B-100 gene ( APOB ), or in the proprotein convertase subtilisin kexine 9 gene ( PCSK9 ). ADH subjects carrying a mutation in LDLR present highly variable plasma LDL-cholesterol (LDL-C). This variability might be due to environmental factors or the effect of some modifying genes such as PCSK9 and APOE . Aims We investigated the molecular basis of thirteen Tunisian ADH families and attempted to determine the impact of PCSK9 and APOE gene variations on LDL-cholesterol levels and on the variable phenotypic expression of the disease. Methods and results Fifty six subjects were screened for mutations in the LDLR gene through direct sequencing. The causative mutation was found to segregate with the disease in each family and a new frameshift mutation, p.Met767CysfsX21, was identified in one family. The distribution of total- and LDL-cholesterol levels, adjusted for age and gender, among homozygous and heterozygous ADH patients varied widely. Within seven families, nine subjects presented low LDL-cholesterol levels despite carrying a mutation in the LDLR gene. To identify the molecular actors underlying this phenotypic variability, the PCSK9 gene was screened using direct sequencing and/or enzymatic restriction analysis, and the apo E genotypes were determined. A new missense variation (p.Pro174Ser) in the PCSK9 gene was identified and characterized as a new putative loss-of-function mutation. Conclusion Genetic variations in PCSK9 and APOE genes could explain only part of the variability observed in the phenotypic expression in Tunisian ADH patients carrying mutations in the LDLR gene. Other genetic variants and environmental factors very probably act to fully explain this phenotypic variability.

Familial hypercholesterolemia (FH), characterized by isolated elevation of plasmatic low-density lipoprotein (LDL) cholesterol and premature coronary heart disease (CHD), is associated with mutations in three major genes: LDL receptor ( LDLR) , apolipoprotein B ( APOB ) and proprotein convertase subtilisin/kexin 9 ( PCSK9) . We have analyzed 5430 Spanish index cases and 2223 relatives since 2004 with LIPOchip ® genetic diagnostic platform, a microarray for the detection of Spanish common mutations in these three genes, including copy number variation (CNV) in LDLR , followed by sequencing analysis of the coding regions of LDLR and exon 26 of APOB , when the result is negative. Samples were received from hospitals of all around Spain. The preferred clinical criterion to diagnose FH was Dutch Lipid Clinic Network (DLCN) score. Our results show that there is a broad spectrum of mutations in the LDLR gene in Spain since about 400 different mutations were detected, distributed along almost the whole LDLR gene. Mutations in APOB (mainly p.Arg3527Gln) covered 6.5% of positive cases and only one PCSK9 mutation was detected. We found correlation between more severe mutations and the clinical diagnosis but also that 28% of FH patients harboring mutations do not have a definite clinical diagnosis. This study analyzes the mutation spectrum in Spain, remarks the importance of genetic diagnosis of FH patients, as well as the cascade screening, and shows how it is being carried out in Spain.

Background: Autosomal recessive hypercholesterolemia (ARH) is an extremely rare inherited hypercholesterolemia, the cause of which is mutations in low-density lipoprotein (LDL) receptor adaptor protein 1 (LDLRAP1) gene. Methods: A total of 146 heterozygous familial hypercholesterolemic (FH) patients with a mutation in LDLR gene were screened for genes encoding proprotein convertase subtilisin/kexin type 9 (PCSK9) and LDLRAP1. Results: Among the 146 subjects, we identified a 79-year-old Japanese female with double mutations in LDLR gene (c.2431A > T) and LDLRAP1 gene (c.606dup). Two other relatives with double mutations in those genes in her family were also identified. Although the proband exhibited massive Achilles tendon xanthoma and coronary and aortic valvular disease, serum LDL-C level of subjects with double mutations was similar with that of subjects with single LDLR mutation (284.0 ± 43.5 versus 265.1 ± 57.4 mg/dl). Conclusion: Additional mutation in LDLRAP1 may account for severer phenotype in terms of xanthoma and atherosclerotic cardiovascular disease in FH patients. © 2011 Elsevier Ireland Ltd. All rights reserved.

Proprotein convertase subtilisin kexin type 9 (PCSK9) is a circulating protein that impairs LDL clearance by promoting the LDL receptor (LDLR) degradation. PCSK9 has emerged as a new pharmacological target for hypercholesterolemia, and different PCSK9 inhibitors are now evaluated in clinical trials. Here, we propose an overview of the clinical perspectives of PCSK9. First, we describe the clinical features of patients with PCSK9 mutations, and how these variations impact the cardiovascular risk. Then, we extensively discuss the potential role of circulating PCSK9 as a new biomarker of lipid metabolism. Indeed, many studies conducted in healthy and type 2 diabetic patients have tested the association of circulating PCSK9 with LDL-cholesterol as well as with multiple metabolic parameters. The overall picture of the clinical relevance of circulating PCSK9 is complicated by the effect of nutritional status and hypolipidemic drugs such as statins, fibrates, ezetimibe on plasma PCSK9 concentrations. Finally, we present a brief overview of the available therapeutic strategies to inhibit PCSK9.

Purpose: Proprotein convertase subtilisin-kexin type 9 (PCSK9) promotes low density lipoprotein (LDL) receptor degradation, thereby providing a key pathway for LDL metabolism. PCSK9 mRNA expression may be upregulated by insulin in murine models. Here we examined effects of exogenous hyperinsulinemia on plasma PCSK9 levels in humans without and with type 2 diabetes mellitus.Methods: A 24 h moderately hyperinsulinemic glucose clamp (30 mU/kg/h) was performed in 8 healthy men and 8 male type 2 diabetic patients. Plasma PCSK9 was measured using a sandwich enzyme-linked immunosorbent assay.Results: Plasma LDL cholesterol and apolipoprotein B were lowered by insulin in healthy subjects and diabetic patients (P 0.15 for all).Conclusion: Plasma PCSK9 levels are not increased by exposure to moderate 24 h hyperinsulinemia in healthy and type 2 diabetic individuals. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

金沢大学医学系研究科, Aim: Familial hypercholesterolemia (FH) is caused by mutations of FH genes, i.e. LDL-receptor (LDLR), PCSK9 and apolipoprotein B (ApoB) gene. We evaluated the usefulness of DNA analysis for the diagnosis of homozygous FH (homo-FH), and studied the frequency of FH in the Hokuriku district of Japan. Methods: Twenty-five homo-FH patients were recruited. LDLR mutations were identified using the Invader assay method. Mutations in PCSK9 were detected by PCR-SSCP followed by direct sequence analysis. Results: We confirmed 15 true homozygotes and 10 compound heterozygotes for LDLR mutations. Three types of double heterozygotes for LDLR and PCSK9 were found. No FH patients due to ApoB mutations were found. The incidences of homo-FH and hetero-FH in the Hokuriku district were 1/171,167 and 1/208, respectively. Conclusions: Our observations underlined the value of FH gene analysis in diagnosing homo-FH and confirmed extraordinarily high frequency of FH in the Hokuriku district of Japan. © 2010 Elsevier Ireland Ltd. All rights reserved.

Genetic variability has been shown to affect statin responsiveness. Participants from the Utrecht Cardiovascular Pharmacogenetics (UCP) studies were enrolled from a population-based registry of pharmacy records linked to hospital discharge records (PHARMO) to investigate tagging SNPs within candidate genes involved in the cholesterol lowering pathway for modification of the effectiveness of statins in reducing the risk of myocardial infarction (MI). Patients who received a prescription for an antihypertensive drug and/or had hypercholesterolemia were selected from the PHARMO database. We designed a nested case-control study in which cases were hospitalized for MI and controls were not. Patients were contacted through their community pharmacies. For this study, only hypercholesterolemic participants were selected. Logistic regression analysis was used to investigate pharmacogenetic interactions. The Heart and Vascular Health Study (HVH) was used to replicate findings from UCP. The study population included 668 cases and 1217 controls. We selected 231 SNPs of which 209 SNPs in 27 genes passed quality control. Ten SNPs in eight genes were found to influence the effectiveness of statins in UCP, of which the most significant interaction was found with SCARB1 rs4765615. Other genes that reached statistical significance (p < 0.05) included two SNPs in PCSK9 (rs10888896 and rs505151 (E670G)), two SNPs in ABCG5 (rs4245786 and rs1864815), LIPC rs16940379, ABCA1 rs4149264, PPARG rs2972164, LRP1 rs715948, and SOAT1 rs2493121. None of the total of 5 SNPs that were available for replication in HVH reached statistical significance. In conclusion, ten SNPs were found to modify the effectiveness of statins in reducing the risk of MI in the UCP study. Five were also tested in the HVH study, but no interactions reached statistical significance. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Proprotein convertase subtilisin kexin/type 9 (PCSK9) is an inhibitor of the low density (LDL) lipoprotein receptor. Plasma PCSK9 is increased by fenofibrate and statins. Here, we determined how standard dose of statin and combined therapy with fenofibrate modulate PCSK9.Randomized, open-label cross-over study investigating the effect of fenofibrate (160 mg), atorvastatin (10 mg), and combination of both in patients with type 2 diabetes mellitus and atherogenic dyslipidemia. After the single administration of atorvastatin and fenofibrate for 6 weeks, patients received both for another 6 weeks. PCSK9, lipids and lipoproteins levels were determined at day 1, weeks 6, 9 and 12.Upon 6 weeks of treatment, atorvastatin decreased LDL-cholesterol by 30% (p0.001) and fenofibrate decreased triglyceride level by 31% (p0.01) and increased HDL-cholesterol by 13% (p0.05). Combination did not show further benefit. Atorvastatin increased PCSK9 by 24% at day 1 and by 14% at week 6 (por = 0.01). Fenofibrate increased PCSK9 by 26% at week 6 (por = 0.01), but had no effect at day 1. Three weeks of combination therapy increased PCSK9 by 42%, 6 weeks by 19% (por = 0.01). PCSK9 changes were not different between treatments over 6-week periods.Fenofibrate and atorvastatin increased circulating PCSK9 in diabetic patients, with no additive effect after 6 weeks of combined therapy.

Objectives Pro-protein convertase subtilisin/kexin type 9 (PCSK9) impairs the low density lipoprotein receptor (LDLr) recyling. To reach the LDLr, the pro-protein must cleave itself in the endoplasmic reticulum. Using a fluorogenic peptide corresponding to the cleavage site, we directly monitored for the first time the cleavage activity of purified human PCSK9 and that of endogenous human wild-type PCSK9 and naturally occurring variants in hepatocytes. Methods Validation of the assay was performed with wild type or PCSK9 deficient primary mouse hepatocytes and immortalized human hepatocytes transfected with antiPCSK9 siRNA. An analysis of the cleaved peptide was performed using mass spectrometry. Pharmacological regulation of the enzyme was studied in human hepatocytes. Expression vectors coding for the variants S127R, D374Y, F216L, S386A were transfected in primary hepatocytes from PCSK9 deficient mice. Results PCSK9 activity was measured in cell lysates and media, at levels 100 times higher than with the human purified recombinant protein. The assay is highly specific for PCSK9 in cell lysate and cell culture media but not in plasma. Pharmacological up- or down-regulation of PCSK9 expression produced paralleled effects on the activity. The catalytic activity of gain-of-function variants S127R, D374Y recapitulated roughly the maturation efficiency estimated by western blots, in contrast with the F216L variant that presented with a 54% lower catalytic activity than the wild-type protein, despite similar proPCSK9 to PCSK9 ratios. Thus, other factors might be involved in the maturation of PCSK9. Conclusion All together, these results shed a new light on PCSK9 enzymatic activity and could help identifying proPCSK9 inhibitors.

Dominant gain-of-function mutations in proprotein convertase subtilisin kexin type 9 (PCSK9) cause familial hypercholesterolaemia (FH) and result in accelerated atherosclerosis and premature coronary heart disease. It is believed that PCSK9 binds to LDL-receptor (LDLR) protein and prevents its recycling to the cell surface; gain-of-function PCSK9 mutants enhance LDLR degradation. Several new variants of PCSK9 have been identified, but their effect on PCSK9 activity has not been determined. We describe a new procedure for assessing the activity of four putative gain-of-function mutations identified in FH patients (D129N, D374H, N425S, R496W). All four mutant proteins were secreted normally from transfected HEK293T cells. Immortalized lymphocytes from normolipaemic controls were incubated with conditioned medium from transfected cells and cell-surface LDLR protein was determined by FACS. D374H was as potent as D374Y in reducing cell-surface LDLR, while the other three mutations were more potent than wild type, but less so than the D374 mutants; this correlated with total serum cholesterol in the patients. Substitution of different amino acids at 374 showed that aspartate in this position was critical; even glutamate at residue 374 increased LDLR degradation. When the assay was carried out with ARH-negative lymphocytes that are unable to internalise the LDLR, D374Y-PCSK9 was able to reduce cell-surface LDLR by 35%, compared with approximately 70% for normal lymphocytes. Thus, PCSK9-mediated LDLR degradation is not entirely dependent on ARH function. We propose a novel ARH-independent pathway for PCSK9 activity on LDLR.

Background We hypothesized that variants in PCSK9 that lower LDL cholesterol levels are associated with reduced prevalence and incidence of peripheral artery disease (PAD). Methods The Atherosclerosis Risk in Communities (ARIC) Study assessed risk factors and PCSK9 variants Y142X and C679X (relevant to blacks) and R46L (relevant to whites) in a cohort of 45–64-year olds in 1987–1989 ( n =13,634). Prevalent PAD ( n =619 cases) was defined by an ankle-brachial index n =895) was identified from 1987 to 1998 by the same PAD criteria or a PAD hospitalization. Results As expected, greater LDL cholesterol was a risk factor for prevalent and incident PAD. 2.4% of blacks and 3.1% of whites were carriers of one of the race-specific PCSK9 variants. Carriers had lower prevalence of PAD compared with non-carriers (2.3% vs. 4.6%). The corresponding age- and sex-adjusted odds ratio of PAD was 0.47 (95% confidence interval, 0.24–0.92). In contrast with the cross-sectional findings, there was no association between PCSK9 variants and incident PAD (age- and sex-adjusted hazard ratio, 1.09 (95% confidence interval, 0.76–1.57)). Conclusions Our study provides mixed evidence that variation in PCSK9 may contribute to genetic risk of PAD.

Caucasian carriers of the T allele at R46L in the proprotein convertase subtilisin/kexin type 9 (PCSK9) locus have been reported to have 15% lower low density lipoprotein (LDL) cholesterol (C) levels and 47% lower coronary heart disease (CHD) risk. Our objective was to examine two PCSK9 single nucleotide polymorphisms (SNPs), R46L and E670G, in 5,783 elderly participants in PROSPER (Prospective Study of Pravastatin in the Elderly at Risk), of whom 43% had a history of vascular disease at baseline, and who were randomized to pravastatin or placebo with followup. In this population 3.5% were carriers of the T allele at R46L, and these subjects had significantly (p

Objective: The combination of simvastatin, an HMG-CoA reductase inhibitor, and ezetimibe, an inhibitor of Niemann-Pick C1-like 1 protein, decreases cholesterol synthesis and absorption and reduces circulating LDL-cholesterol concentrations. The molecular mechanisms underlying the pronounced lipid-lowering effects of this combination have not been fully elucidated in humans. Methods and results: One center, prospective, randomized, parallel three-group study in 72 healthy men (mean age 32 ± 9 years, mean body mass index 25.7 ± 3.2 kg/m 2 ). Each group of twenty-four subjects received a 14-day treatment with either ezetimibe (10 mg/day), simvastatin (40 mg/day) or their combination. Lipid levels, the ratio of non-cholesterol sterols to cholesterol concentrations (used as markers of cholesterol synthesis and absorption), cell surface LDL receptor (LDLR) protein as well as LDLR and HMG-CoA reductase gene expression in mononuclear blood cells were measured at baseline and at the end of the study. LDL-C decreased in all groups. Simvastatin decreased, ezetimibe increased and their combination had no effect on HMG-CoA reductase activity. Simvastatin and the combination of ezetimibe and simvastatin increased the HMG-CoA reductase and LDLR gene expression while ezetimibe had no effect. The cell surface LDLR protein expression remained unchanged in all groups. The combination of ezetimibe and simvastatin increased the expression of the serine protease proprotein convertase subtilisin/kexin 9 (PCSK9), an enzyme shown to down-regulate LDLR protein levels. Conclusions: The co-administration of ezetimibe and simvastatin abrogates the ezetimibe-induced increase in cholesterol synthesis and up-regulates the LDLR gene but not protein expression, an effect possibly mediated through a parallel upregulation of PCSK9 expression. © 2007 Elsevier Ireland Ltd. All rights reserved.

Familial hypercholesterolaemia (FH) results from defective catabolism of low density lipoproteins (LDL), leading to premature atherosclerosis and early coronary heart disease. It is commonly caused by mutations in LDLR , encoding the LDL receptor that mediates hepatic uptake of LDL, or in APOB , encoding its major ligand. More rarely, dominant mutations in PCSK9 or recessive mutations in LDLRAP1 ( ARH ) cause FH, gene defects that also affect the LDL-receptor pathway. We have used multiplex ligation-dependent probe amplification (MLPA) to identify deletions and rearrangements in LDLR , some not detectable by Southern blotting, thus completing our screening for mutations causing FH in a group of FH patients referred to a Lipid Clinic in London. To summarise, mutations in LDLR were found in 153 unrelated heterozygous FH patients and 24 homozygotes/compound heterozygotes, and in over 200 relatives of 80 index patients. LDLR mutations included 85 different point mutations (7 not previously described) and 13 different large rearrangements. The APOB R3500Q mutation was present in 14 heterozygous patients and a mutation in PCSK9 in another 4; LDLRAP1 mutations were found in 4 "homozygous" FH patients. Our data confirm that DNA-based diagnosis provides information that is important for management of FH in a considerable number of families.

The European Atherosclerosis Society (EAS) Consensus Panel on Familial Hypercholesterolaemia (FH) has today published a position statement on homozygous FH. This follows the first EAS Consensus Statement, which highlighted the extent of underdiagnosis and undertreatment of heterozygous FH [1]. The publication is available to download from: http://eurheartj. oxfordjournals.org/content/early/2014/07/22/eurheartj.ehu274. full.html?papetoc.

Rationale A strong risk factor for atherosclerosis– the leading cause of heart attacks and strokes– is the elevation of low-density lipoprotein cholesterol (LDL-C) in blood. The LDL receptor (LDLR) is the primary pathway for LDL-C removal from circulation, and their levels are increased by statins –the main treatment for high blood LDL-C. However, statins have low efficiency because they also increase PCSK9 which targets LDLR for degradation. Since microRNAs have recently emerged as key regulators of cholesterol homeostasis, our aim was to identify potential microRNA-based therapeutics to decrease blood LDL-C and prevent atherosclerosis. Methods and results We over expressed and knocked down miR-27a in HepG2 cells to assess its effect on the expression of key players in the LDLR pathway using PCR Arrays, Elisas, and Western blots. We found that miR-27a decreases LDLR levels by 40% not only through a direct binding to its 3′ untranslated region but also indirectly by inducing a 3-fold increase in PCSK9, which enhances LDLR degradation. Interestingly, miR-27a also directly decreases LRP6 and LDLRAP1, two other key players in the LDLR pathway that are required for efficient endocytosis of the LDLR-LDL-C complex in the liver. The inhibition of miR-27a using lock nucleic acids induced a 70% increase in LDLR levels and, therefore, it would be a more efficient treatment for hypercholesterolemia because of its desirable effects not only on LDLR but also on PCSK9. Conclusion The results presented here provide evidence supporting the potential of miR-27a as a novel therapeutic target for the prevention of atherosclerosis.

Background Proper screening and diagnosis of familial hypercholesterolemia (FH) is of critical importance for cardiovascular prevention. However, the clinical diagnosis of FH remains difficult partly because its phenotype can vary between different ethnicities. The aim of this study was to determine the clinical features and the best diagnostic approach in Korean FH patients. The predictors of putative pathogenic mutations and coronary artery disease (CAD) were also identified. Methods and Results Ninety-seven patients with low-density lipoprotein-cholesterol >190 mg/dL and xanthoma or FH-compatible family history were included. Putative pathogenic mutations in LDLR , APOB , or PCSK9 genes were identified in 32% of the enrolled patients. The subjects were classified according to four sets of clinical criteria (Simon Broome, Dutch, MEDPED, Japanese). The mutation rates in definite type FH of Simon Broome or Dutch criteria were 35%–37% and lower in our patients than in those of other countries. The mutation detection rate by MEDPED criteria was 67%–75% and higher than those based on other criteria. The best low-density lipoprotein-cholesterol (LDL-C) threshold for predicting mutations was 225 mg/dL. LDL-C was found to be the only independent predictor of mutation carriers, while hypertension and low high-density lipoprotein-cholesterol were predictive of CAD. Conclusions The conventional clinical criteria showed limited mutation detection power and low specificities in Korean FH patients, in whom the best LDL-C threshold for putative mutation was 225 mg/dL. Traditional cardiovascular risk factors were also significantly associated with CAD risk in this population.

Background/Objective Familial hypercholesterolemia (FH) is an autosomal dominant disorder caused by mutations in LDLR, APOB, or PCSK9 . Polygenicity is a plausible cause in mutation-negative FH patients based on LDL cholesterol (LDL-C)-associated single nucleotide polymorphisms (SNPs) identified by the Global Lipids Genetics Consortium (GLGC). However, there are limited data regarding the polygenic cause of FH in Asians. Methods We gathered data from 66 mutation-negative and 31 mutation-positive Korean FH patients, as well as from 2274 controls who participated in the Korean Health Examinee (HEXA) shared control study. We genotyped the patients for six GLGC SNPs and four East Asian LDL-C-associated SNPs and compared SNP scores among patient groups and controls. Results Weighted mean 6- and 4-SNP scores (0.67 [SD = 0.07] and 0.46 [0.11], respectively) were both significantly associated with LDL-C levels in controls ( p = 2.1 × 10 −4 , R 2 = 0.01 and p = 5.0 × 10 −12 , R 2 = 0.02, respectively). Mutation-negative FH patients had higher 6-SNP (0.72 [0.07]) and 4-SNP (0.49 [0.08]) scores than controls ( p = 1.8 × 10 −8 and p = 3.6 × 10 −3 , respectively). We also observed higher scores in mutation-positive FH patients compared with controls, but the difference did not reach statistical significance. Conclusion The present study demonstrates the utility of SNP score analysis for identifying polygenic FH in Korean patients by showing that small-effect common SNPs may cumulatively elevate LDL-C levels.

A locus on chromosome 1p34.1-p32 has been linked to autosomal dominant Familial Hypercholesterolemia (FH) and is termed the third FH locus. We tested whether this third FH locus is linked to the FH phenotype in 20 Danish families, with 158 members, without pathogenic mutations in the genes, encoding the low-density lipoprotein (LDL) receptor or apolipoprotein B (apoB). We could exclude the third FH locus as a cause of FH by genetic linkage analysis in the families taken together. Since haplotype analysis of each family nevertheless suggested that the FH phenotype co-segregated in a manner consistent with linkage to the third FH locus in three small pedigrees, we performed sequencing analysis without being able to demonstrate mutations in the proprotein convertase subtilisin/kexin type 9 (PCSK9) gene, the main candidate gene in the third FH locus. By the same combination of genetic linkage and molecular analysis we could also exclude mutations in the gene for the LDL receptor adaptor protein and in the gene for cholesterol-7-alpha-hydroxylase as causes of FH in our sample. Although not indicating linkage to any known loci, our data still indicate that another dominant gene may be involved in causing a FH phenotype.

Objective To assess the mechanism of long-term LDL-C-lowering effect of ezetimibe-plus-statin. Methods Coronary artery disease patients whose LDL-C ≥70 mg/dL after treatment with atorvastatin 10 mg/day or rosuvastatin 2.5 mg/day were randomly assigned to receive ezetimibe 10 mg/day + statin ( n = 78) or double-dose statin ( n = 72) for 52 weeks. Results Greater LDL-C reduction was observed and maintained until 52 weeks in ezetimibe-plus-statin, while LDL-C levels re-increased after 12 weeks in double-dose statin. Although lathosterol/TC increased, campesterol/TC decreased more in ezetimibe-plus-statin. In contrast, lathosterol/TC unchanged and campesterol/TC increased, increasing campesterol/lathosterol ratio for 52 weeks in double-dose statin. Plasma PCSK9 levels were higher in double-dose statin than in ezetimibe-plus-statin at 12 weeks, but similar at 52 weeks. Conclusion Although the difference in PCSK9 between 2 groups was transient, that in both campesterol and lathosterol persisted until 52 weeks. These results demonstrated simultaneous inhibition of cholesterol absorption and synthesis provides stable and greater decrease in LDL-C levels.

Purpose: Apolipoprotein M (apoM) retards atherosclerosis development in murine models, and may be regulated by pathways involved in LDL metabolism. Proprotein convertase subtilisin-kexin type 9 (PCSK9) plays a key role in LDL receptor processing. We determined the extent to which plasma apoM is related to PCSK9 levels in subjects with varying degrees of obesity.Methods: We sought correlations between plasma apoM and PCSK9, measured using recently developed ELISAs, in 79 non-diabetic subjects.Results: ApoM and PCSK9 levels were both correlated positively with total cholesterol, non-HDL cholesterol, LDL cholesterol and apoB (P Conclusions: The PCSK9 pathway may contribute to plasma apoM regulation in humans. The influence of PCSK9 on circulating apoM appears to be modified by adiposity. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Sterol regulatory element-binding proteins (SREBPs) regulate homeostasis of LDL, HDL and triglycerides. This study was aimed to determine if inhibition of SREBPs by methyl protodioscin (MPD) regulates downstream gene and protein expressions of lipid metabolisms. In THP-1 macrophages, MPD increases levels of ABCA1 mRNA and protein in dose- and time-dependent manners, and apoA-1-mediated cholesterol efflux. The underlying mechanisms for the effects is that MPD inhibits the transcription of SREBP1c and SREBP2, and decreases levels of microRNA 33a/b hosted in the introns of SREBPs, which leads to reciprocally increase ABCA1 levels. In HepG2 cells, MPD shows the same effects as these observed in THP-1 macrophages. MPD also decreases the gene expressions of HMGCR, FAS and ACC for cholesterol and fatty acid synthesis. MPD further promotes LDL receptor through reducing the PCSK9 level. Collectively, the study demonstrates that MPD potentially increase HDL cholesterol while reducing LDL cholesterol and triglycerides.

Background/Objective Familial Hypercholesterolaemia (FH) is caused by mutations in genes of the Low Density Lipoprotein (LDL) receptor pathway. A definitive diagnosis of FH can be made by the demonstration of a pathogenic mutation. The Wales FH service has developed scoring criteria to guide selection of patients for DNA testing, for those referred to clinics with hypercholesterolaemia. The criteria are based on a modification of the Dutch Lipid Clinic scoring criteria and utilise a combination of lipid values, physical signs, personal and family history of premature cardiovascular disease. They are intended to provide clinical guidance and enable resources to be targeted in a cost effective manner. Methods 623 patients who presented to lipid clinics across Wales had DNA testing following application of these criteria. Results The proportion of patients with a pathogenic mutation ranged from 4% in those scoring 5 or less up to 85% in those scoring 15 or more. LDL-cholesterol was the strongest discriminatory factor. Scores gained from physical signs, family history, coronary heart disease, and triglycerides also showed a gradient in mutation pick-up rate according to the score. Conclusion These criteria provide a useful tool to guide selection of patients for DNA testing when applied by health professionals who have clinical experience of FH.

International audience; OBJECTIVE: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is highly expressed in the kidney, where its function remains unclear. In vitro data suggested that PCSK9 could impair the trafficking of the epithelial Na channel (ENaC). Here, we aimed at determining the consequences of PCSK9-deficiency on blood pressure, sodium balance and ENaC function in vivo in mice. METHODS: Blood pressure was measured using non-invasive tail-cuff system or radiotelemetry under basal conditions in male and female PCSK9(+/+) and PCSK9(-/-) mice, as well as in models of hypertension: l-NAME (2 mg/kg/day), angiotensin II (1 mg/kg/day) and deoxycorticosterone acetate (DOCA)-salt in male mice only. Plasma and urine electrolytes (Na(+), K(+), Cl(-)) were collected under basal conditions, after DOCA-salt and amiloride treatment. Renal expression of ENaC subunits was assessed by western blotting. RESULTS: PCSK9-deficiency did not alter both basal blood pressure and its increase in salt-insensitive (l-NAME) and salt-sensitive (Ang-II and DOCA-salt) hypertension models. Plasma PCSK9 concentrations were increased by 2.8 fold in DOCA-salt-induced hypertension. The relative expression of the cleaved, active, 30-kDa αENaC subunit was significantly increased by 32% in kidneys of PCSK9(-/-) mice under basal, but not under high-Na(+) diet or DOCA-salt conditions. Amiloride increased urinary Na(+) excretion to similar level in both genotypes, indicating that ENaC activity was not affected by PCSK9-deficiency. CONCLUSIONS: Despite an increase of cleaved αENaC under basal condition, PCSK9(-/-) mice display normal sodium balance and blood pressure regulation. Altogether, these data are reassuring regarding the development of PCSK9 inhibitors in hypercholesterolemia.

High fructose diet (HFD) induces dyslipidemia and insulin resistance in experimental animals and humans with incomplete mechanistic understanding. By utilizing mice and hamsters as in vivo models, we investigated whether high fructose consumption affects serum PCSK9 and liver LDL receptor (LDLR) protein levels.Feeding mice with an HFD increased serum cholesterol and reduced serum PCSK9 levels as compared with the mice fed a normal chow diet (NCD). In contrast to the inverse relationship in mice, serum PCSK9 and cholesterol levels were co-elevated in HFD-fed hamsters. Liver tissue analysis revealed that PCSK9 mRNA and protein levels were both reduced in mice and hamsters by HFD feeding, however, liver LDLR protein levels were markedly reduced by HFD in hamsters but not in mice. We further showed that circulating PCSK9 clearance rates were significantly lower in hamsters fed an HFD as compared with the hamsters fed NCD, providing additional evidence for the reduced hepatic LDLR function by HFD consumption. The majority of PCSK9 in hamster serum was detected as a 53 kDa N-terminus cleaved protein. By conducting in vitro studies, we demonstrate that this 53 kDa truncated hamster PCSK9 is functionally active in promoting hepatic LDLR degradation.Our studies for the first time demonstrate that high fructose consumption increases serum PCSK9 concentrations and reduces liver LDLR protein levels in hyperlipidemic hamsters. The positive correlation between circulating cholesterol and PCSK9 and the reduction of liver LDLR protein in HFD-fed hamsters suggest that hamster is a better animal model than mouse to study the modulation of PCSK9/LDLR pathway by atherogenic diets.

Lowering low-density lipoprotein cholesterol (LDL-C) reduces the risk of cardiovascular disease: each 1.0 mmol/L (38.7 mg/dL) reduction in LDL-C reduces the incidence of major coronary events, coronary revascularizations, and ischemic stroke by approximately 20%. Statins are a well-established treatment option for dyslipidemia, with LDL-C reduction in the range of 27-55%. Several lipid goal-driven guidelines recommend reducing LDL-C to

Objective This article reviews the mechanism by which the low density lipoprotein receptor (LDLR) that has bound proprotein convertase subtilisin/kexin type 9 (PCSK9), is rerouted to intracellular degradation instead of being recycled. Methods A search of relevant published literature has been conducted. Results PCSK9 binds to the LDLR at the cell surface. It is the catalytic domain of PCSK9 that binds to the epidermal growth factor repeat A of the LDLR. The LDLR:PCSK9 complex is internalized through clathrin-mediated endocytosis. Due to an additional electrostatic interaction at acidic pH between the C-terminal domain of PCSK9 and the ligand-binding domain of the LDLR, PCSK9 remains bound to the LDLR in the sorting endosome. As a consequence, the LDLR fails to adopt a closed conformation and is degraded instead of being recycled. The mechanism for the failure of the LDLR to recycle appears to involve ectodomain cleavage of the extended LDLR by a cysteine cathepsin in the sorting endosome. The cleaved LDLR ectodomain will be confined to the vesicular part of the sorting endosome for degradation in the endosomal/lysosomal tract. Conclusion Ectodomain cleavage of an LDLR with bound PCSK9 in the sorting endosome disrupts the normal recycling of the LDLR.

Studies performed in rodents have suggested a role for proprotein convertase subtilisin/kexin type 9 (PCSK9) in insulin resistance and impaired body fat distribution. Our objective was to examine the relationships between markers of adiposity and insulin resistance and plasma PCSK9 levels in humans. In addition, we explored the effect of a one-year lifestyle modification program on plasma PCSK9 levels in abdominally obese, dyslipidemic men.Plasma PCSK9 levels were measured by ELISA in 175 abdominally obese, dyslipidemic sedentary men. Of these abdominally obese men, 117 non-diabetic individuals completed a one-year lifestyle modification program aiming at increasing cardiorespiratory fitness levels and improving nutritional quality.We found no association between plasma PCSK9 levels and body mass index, waist circumference, fat and fat-free mass, or visceral and subcutaneous adipose tissue measured by computed tomography. Compared to men with the lowest PCSK9 levels (bottom tertile), those with the highest PCSK9 levels (top tertile) had the most detrimental lipoprotein-lipid profile including lower LDL particle size (253.6 ± 4.0 vs. 251.6 ± 4.0 Å, p 0.05) and higher apolipoprotein C-III levels (36.8 ± 10.6 vs. 32.3 ± 32.3, p 0.05). These men were also characterized by higher HOMA-IR indices (6.78 ± 3.01 vs. 5.54 ± 2.91, p 0.05). After one year, study participants lost on average 6.7 ± 4.6 kg (p 0.0001). Plasma PCSK9 decreased by 9.2 ± 53.7 ng/ml (3.8%, p = 0.07).Plasma PCSK9 levels are not associated with body fat distribution indices, modestly associated with markers of insulin resistance and LDL particle size and are slightly affected by a lifestyle modification program in abdominally obese men.

Background: There is little knowledge about familial hypercholesterolemia in Brazil. This study presents the first results of genetic cascade screening performed in the city of Sao Paulo. Material and methods: Two-hundred and forty-eight suspected index cases were initially included. DNA was extracted from peripheral blood and the complete coding sequence of low-density lipoprotein receptor, exon 7 of proprotein convertase subtilisin/kexin type 9 gene and part of exon 26 of apolipoprotein B genes were sequenced. Multiplex Ligation-dependent Probe Amplification was performed on cases where a causal mutation was not identified through sequencing. After the identification of a causal mutation screening in first-degree relatives was pursued. Results: From 248 index cases, a mutation was found in 125 individuals (50.4%). 394 relatives were included in the cascade screening program and a mutation was identified in 59.4%. Seventy different causal mutations in the low-density lipoprotein receptor gene (97.2%) and 2 in the apolipoprotein B gene (2.8%) were found. No mutations were encountered in the proprotein convertase subtilisin/kexin type 9 gene. Mutations in exons 14 and 4 were the most prevalent and, 10 cases of true homozygotes (8 index cases and 2 relatives) and 1 compound heterozygote were identified. The most frequent mutation found was of Lebanese origin, the p.(Cys681*) mutation in exon 14 (8.5%). Conclusion: Genetic familial hypercholesterolemia cascade screening is feasible in Brazil and leads to identification of a mutation in approximately half of the index cases with higher rates of success in their relatives.

Recent studies have suggested that proprotein convertase subtilisin/kexin type 9 (PCSK9) is associated with atherosclerosis and plays a potential role in inflammation. However, the correlation between PCSK9 and white blood cell count (WBCC) has not yet been assessed. The objective of the present study was to examine the association of the WBCC and its subset counts with plasma PCSK9 levels in patients with stable coronary artery disease (CAD).In this cross-sectional study, a total of 251 consecutive, stable CAD patients who were not treated with lipid-lowering drugs were enrolled at our center between October 2012 and October 2013. The baseline clinical characteristics were collected, and the plasma PCSK9 levels were determined using ELISA. The associations of plasma PCSK9 levels with the WBCC and its subsets were investigated.In the overall population, plasma PCSK9 levels were positively associated with the WBCC (r = 0.167, p = 0.008). Multivariable regression analysis revealed that the plasma PCSK9 levels were significantly and independently associated with the WBCC (β = 0.217, p0.001) and its subsets (neutrophil β = 0.152, p0.05; lymphocyte β = 0.241, p0.001). However, the relationships between PCSK9 and WBCC and its subsets remained significant in men (WBCC r = 0.234, p = 0.001; neutrophil r = 0.181, p = 0.014; lymphocyte r = 0.226, p = 0.002) but were not significant in women when the analysis was performed based on gender.These data demonstrate that the plasma PCSK9 levels are independently associated with the WBCC and its subsets, suggesting a potential interaction between PCSK9 and chronic inflammation in patients with CAD.

Objectives Serum low density lipoprotein-cholesterol (LDL-C) correlates positively with serum PCSK9 in the general population, consistent with PCSK9 being a determinant of LDL-C levels. Patients with chronic kidney disease (CKD) on hemodialysis (HD) have lower total cholesterol (TC) and LDL-C compared to the general population. Serum PCSK9 and its relationship with serum lipids have not been reported in CKD patients on HD (CKD-HD). Methods We measured serum PCSK9 by ELISA and lipid levels in 66 CKD-HD patients and compared them to 178 non-CKD subjects. Since statins increase serum PCSK9 levels, CKD-HD patients were separated into those not on statin therapy (HD-NS, n = 32) and those taking statins (HD-S, n = 34). No control subjects were on statin therapy. Results Serum PCSK9, TC, LDL-C and HDL-C levels were significantly lower in the CKD-HD group ( n = 66) compared to the control group. HD-NS patients showed lower PCSK9, TC and LDL-C levels than control subjects and PCSK9 levels correlated with TC and LDL-C levels ( r = 0.35, p = 0.050; r = 0.423, p = 0.0158 respectively) as well as TG levels ( r = 0.413, p = 0.0188). In HD-S patients, PCSK9 levels were not significantly different from the non-CKD group. There was no correlation between PCSK9 levels and TC and LDL-C levels in the HD-S group. Conclusion Our data are the first quantitative analysis of serum PCSK9 levels in CKD-HD patients. We show that serum PCSK9 in HD-NS patients is decreased and it retains a positive correlation with LDL-C, suggesting that PCSK9 may remain a significant determinant of LDL-C in CKD-HD subjects. We also show that statin therapy disrupts the correlation between LDL-C and PCSK9 in CKD-HD patients. These data suggest that the regulation of LDL-C by PCSK9 remains intact in CKD-HD patients. PCSK9 may also play a role in the metabolism of triglyceride-rich lipoproteins in CKD-HD patients.

Background Autosomal dominant hypercholesterolemia (ADH) is caused by mutations in the low density lipoprotein receptor ( LDLR ), its ligand apoB ( APOB ) or proprotein convertase subtilisin/kexin type 9 ( PCSK9 ) genes. Yet DNA sequencing does not identify mutations in these genes in a significant number of cases, suggesting that ADH has multiple genetic etiologies. Methods Through a combination of clinical examination, biochemical analysis, candidate gene approach and next-generation exome sequencing we investigated the genetic basis of an ADH phenotype in a proband of an Italian origin. Results The proband presented with an acute myocardial infarction at age 43. He had tendinous xanthomas, xanthelasmas and elevated levels of total and LDL cholesterol, at 11.2 and 9.69 mmol/L, respectively, with normal levels of HDL cholesterol and triglycerides at 1.62 and 1.13 mmol/L, respectively. HPLC lipoprotein profile showed selective increase in LDL-C. DNA sequencing did not identify any mutation in the LDLR , PCSK9 , LDLRAP1 and APOB gene. We then performed exome sequencing on three individuals from the family. The strongest evidence of association was found for the previously identified apolipoprotein E mutation ( APOE, chromosome 19:45412053-55) known as APOE Leu167del, an in-frame three base-pair deletion. Computational biology confirmed the deleterious nature of this mutation. The Leu167del mutation is predicted to alter the protein structure of apoE near the α-helix within the receptor binding domain. Conclusions This report confirms a previous report that ADH can be caused by mutations within the APOE gene and represents the 4th loci causing ADH. Standard screening for ADH should include APOE gene.

Familial hypercholesterolemia (FH) is an autosomal dominant disease characterized by hypercholesterolemia, tendon xanthomas, and premature coronary heart disease. FH is caused by mutations of "FH genes," which include the LDL-receptor (LDLR), apolipoprotein B-100 (APOB) or proprotein convertase subtilisin/kexin type 9 (PCSK9). We evaluated the usefulness of FH gene analysis for diagnosing homozygous FH (homo-FH), particularly in cases caused by gain-of-function (g-o-f) mutations in PCSK9 (PCSK9 E32K).To evaluate the frequency of homo-FH caused by PCSK9 E32K compared with FH due to other genetic causes and to report the phenotypic features of homo-FH caused by PCSK9 E32K.Genomic DNA was prepared from white blood cells, and LDLR and PCSK9 mutations were identified using the Invader assay method.Of the 1055 hetero-FH patients, 62 patients (5.9%) carried the PCSK9 E32K mutation, while in the 82 alleles of 41 homo-FH patients, 13 (15.9%) had double mutations of LDLR allele and PCSK9 E32K mutation. Mean plasma total cholesterol (TC) (9.93 ± 2.95 mmol/L, mean ± SD) in true homo-FH cases with PCSK9 E32K or double hetero-FH cases with PCSK9 E32K and LDLR mutations were significantly lower than those in true homo-FH (18.06 ± 4.96 mmol/L) and compound heterozygous cases with LDLR mutations (14.84 ± 1.62 mmol/L). Mean plasma TC concentrations in the 59 hetero-FH cases with PCSK9 E32K (7.21 ± 1.55 mmol/L) were significantly lower than those (8.94 ± 1.53 mmol/L) in the hetero-FH by LDLR mutations.FH caused by PCSK9 g-o-f mutations is relatively common in Japan and causes a mild type of homo- and hetero-FH compared with FH caused by LDLR mutations.

Objectives: To assess the lipid-lowering efficacy of ezetimibe in dyslipidemic cynomolgus monkeys comparing two dosing methods, and to evaluate PCSK9 plasma levels during dyslipidemia induction by feeding a high-fat/high-cholesterol diet (HFD), ezetimibe (Zetia , Ezetrol) treatment, ezetimibe washout, and HFD washout. Methods and results: Twenty dyslipidemic cynomolgus monkeys on HFD for seven months (LDL cholesterol 100e400 mg/dL) were randomized into two groups and treated with ezetimibe for two weeks, either by oral gavage or by using food treats. The lipid-lowering effects of ezetimibe were identical between the two groups. After treatment, mean LDL cholesterol was decreased by 58% (174 e72 mg/dL), total cholesterol by 42% (241e138 mg/dL), and PCSK9 levels were increased by 137% (147 e314 ng/mL). PCSK9 levels on regular diet before and after HFD were also inversely correlated to LDL cholesterol. Conclusions: In a cynomolgus dyslipidemia model, PCSK9 levels are inversely correlated with LDL cholesterol in the absence of statin treatment, regardless whether lipid changes are modulated by diet or ezetimibe treatment. 2013 Published by Elsevier Ireland Ltd.

Objective To determine the spectrum of gene mutations and the genotype–phenotype correlations in patients with Autosomal Dominant Hypercholesterolemia (ADH) identified in Italy. Methods The resequencing of LDLR , PCSK9 genes and a selected region of APOB gene were conducted in 1018 index subjects clinically heterozygous ADH and in 52 patients clinically homozygous ADH. The analysis was also extended to 1008 family members of mutation positive subjects. Results Mutations were detected in 832 individuals: 97.4% with LDLR mutations, 2.2% with APOB mutations and 0.36% with PCSK9 mutations. Among the patients with homozygous ADH, 51 were carriers of LDLR mutations and one was an LDLR / PCSK9 double heterozygote. We identified 237 LDLR mutations (45 not previously reported), 4 APOB and 3 PCSK9 mutations. The phenotypic characterization of 1769 LDLR mutation carriers (ADH-1) revealed that in both sexes independent predictors of the presence of tendon xanthomas were age, the quintiles of LDL cholesterol, the presence of coronary heart disease (CHD) and of receptor negative mutations. Independent predictors of CHD were male gender, age, the presence of arterial hypertension, smoking, tendon xanthomas, the scalar increase of LDL cholesterol and the scalar decrease of HDL cholesterol. We identified 13 LDLR mutation clusters, which allowed us to compare the phenotypic impact of different mutations. The LDL cholesterol raising potential of these mutations was found to vary over a wide range. Conclusions This study confirms the genetic and allelic heterogeneity of ADH and underscores that the variability in phenotypic expression of ADH-1 is greatly affected by the type of LDLR mutation.

Objective To determine the spectrum of mutations associated with familial hypercholesterolaemia (FH) and their detection rate in the FH Western Australia (FHWA) Program. Methods Mutation testing of the LDLR gene, plus select regions in APOB and PCSK9 , was performed in the first 343 patients considered to be phenotypic index cases of FH and classified on the basis of the Dutch Lipid Clinic Network Criteria (DLCNC) score as "possible", "probable", or "definite" FH. Results Overall, 86 different pathogenic (or likely pathogenic) mutations were identified in 129 patients, including four compound heterozygotes manifesting a more severe clinical phenotype. Fourteen of these mutations were novel and twelve (9.6%) were large deletions/duplications of the LDLR . The most common mutations were the familial defective apoB-100 mutation APOB p.Arg3527Gln (7.2%) and an LDLR intron 3 splice site mutation c.313 + 1G > A (4.8%). While 70% of ‘definite' FH patients were found to carry a mutation, only 29% of ‘probable' and 11% of ‘possible' FH patients were mutation-positive. Conclusion This information provides a useful DNA database on which to base ongoing cascade screening for FH and future research into the genetic aetiology of FH in Western Australia. These findings suggest genetic testing should be prioritised to those with high DLCNC scores and offers a cost-effective family screening method from FH index cases, leading to detection of other previously undiagnosed and younger family members, enabling early instigation of intervention and preventative measures for premature coronary heart disease.

Objective Genome-wide association studies (GWAS) are useful in studying the complex pathways underlying diseases such as atherosclerosis; however, additional testing is often necessary to identify the disease causal genes linked to GWAS loci. We used siRNA-mediated gene knockdown in primary human hepatocytes (PHuH) to identify potential GWAS causal genes affecting the hepatic secretion of apolipoprotein B (ApoB), ApoA1, and proprotein convertase subtilisin/kexin type 9. Materials and methods Candidate causal genes within GWAS loci affecting human plasma levels of total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides were identified from the literature; 191 genes were selected from 74 loci. A functional siRNA screen was performed using PHuH. Results Four genes: poly (ADP-ribose) polymerases member 10, haptoglobin, fucosyltransferase 1, and lysophosphatidic acid receptor 2 were identified and confirmed. Knocking down these genes reduced cell-associated and secreted ApoB levels. Conclusion Modification of these four genes may affect plasma lipids through modulation of ApoB secretion.