Low Density Lipoprotein Receptor Activity Research Articles

Influence of LDLR pathogenic variants on LDL receptor activity in lymphocytes of patients with Familial Hypercholesterolemia

Influence of LDLR pathogenic variants on LDL receptor activity in lymphocytes of patients with Familial Hypercholesterolemia

Case Series: Patients with Hypo-Responsiveness to PCSK9 Inhibitor Therapy

<h3>Lead Author's Financial Disclosures</h3> Nothing to disclose. <h3>Study Funding</h3> None. <h3>Background/Synopsis</h3> Proprotein convertase subtilisin/Kexin type 9 inhibitors (PCSK9i) [alirocumab, evolocumab] are fully human monoclonal antibodies that bind to plasma PCSK9 and prevent LDL receptor degradation. They reduce LDL-C by 50-70% and improve cardiovascular morbidity and mortality by 50% (Gouni-Berthold I.,2017). They are indicated as an adjunct to diet and maximally tolerated statin in individuals with familial hypercholesterolemia or clinical atherosclerotic cardiovascular disease who require additional LDL-C lowering. Evolocumab reduced LDL-C by 30% or greater in 99.8% patients, and alirocumab reduced LDL-C by atleast 15% in 98.9% patients (Qamar et al.,2019, Bays et al.,2018). About 87-98% achieve LDL-C goal with PCSK9i (Gouni-Berthold I.,2017). Hence, majority of patients on PCSK9i are expected to have a substantial and consistent LDL-C reduction. But, hypo-responsiveness to PCSK9i (less than 30% LDL-C reduction from baseline at all time points, i.e., beyond two standard deviations of mean for expected LDL-C reduction [Qamar et al.,2019]) are encountered more commonly in the clinical setting than expected. <h3>Objective/Purpose</h3> Assess factors contributing to hypo-responsiveness to PCSK9i. <h3>Methods</h3> A case series of five patients with hypo-responsiveness to PCSK9i reported in table 1. <h3>Results</h3> Unusual response to PCSK9i occur 3-fold higher in real-world than reported in clinical trials (Warden et al.,2020). Maximal PCSK9i LDL-C reduction occurs in 14-days (Chaudhary et al.,2017). In clinical trials, LDL-C was obtained at the end of dosing interval. Evolocumab reduces LDL-C by 85% at midpoint and by 60% at end of dosing interval (Qamar et al.,2019). Less than 15% LDL-C reduction in ODYSSEY trials was reported due to poor adherence to PCSK9i or concurrent lipid-lowering therapy (Bays et al.,2018). All our patients were adherent to treatment and had accurate injection techniques. Our patients have unique genetics and co-morbidities, which might have contributed to interindividual variation and hypo-responsiveness to PCSK9i. Elevated Lp(a) co-measured with LDL-C can contribute to suboptimal response as PCSK9i can lower Lp(a) by 15-30% only (Ruscica et al.,2020). PCSK9 and Lp(a) levels increase in nephrotic syndrome (Pavlakou et al.,2017, Hopewell et al.,2018). Disorders with very low LDL receptor activity can influence response to PCSK9i. There is a potential for immunogenicity, but anti-drug antibodies impact on clinical response to PCSK9i is unknown. There is no evidence of insufficient PCSK9 blockade, difference with switching PCSK9i, or changing injection site. <h3>Conclusions</h3> Careful medication reconciliation and injection technique assessment are the initial steps in evaluating hypo-responsiveness to PCSK9i. Understanding possible etiologies for hypo-responsiveness to PCSK9i might help advance lipid-lowering pharmacology.

Impact of Soy β-Conglycinin Peptides on PCSK9 Protein Expression in HepG2 Cells.

Background: Dyslipidaemias, particularly elevated plasma low-density lipoprotein cholesterol (LDL-C) levels, are major risk factors for cardiovascular disease (CVD). Besides pharmacological approaches, a nutritional strategy for CVD prevention has gained increasing attention. Among functional foods, the hypocholesterolemic properties of soy are driven by a stimulation of LDL-receptor (LDL-R) activity. Aim: To characterize the effect of two soy peptides, namely, β-conglycinin-derived YVVNPDNDEN and YVVNPDNNEN on the expression of proprotein convertase subtilisin/kexin type 9 (PCSK9), one of the key-regulators of the LDL-R. Methods: PCSK9 promoter activity (luciferase assay), PCSK9 protein expression (WB) and secretion (ELISA), PCSK9 interaction with LDL-R (binding assay) and human HepG2 cells were the objects of this investigation. Results: Treatment with YVVNPDNNEN peptide has led to a rise in PCSK9 gene expression (90.8%) and transcriptional activity (86.4%), and to a decrement in PCSK9 intracellular and secreted protein (−42.9%) levels. YVVNPDNNEN peptide reduced the protein expression of transcriptional factor HNF1α. Most changes driven by YVVNPDNDEN peptide were not statistically significant. Neither peptide inhibited the PCSK9–LDLR interaction. Conclusions: Although sharing a common effect on LDL-R levels through the inhibition of 3-hydroxy-3-methylglutaryl CoA reductase activity, only the YVVNPDNNEN peptide has an additional mechanism via the downregulation of PCSK9 protein levels.

Posttranscriptional Regulation of the Human LDL Receptor by the U2-Spliceosome

The LDLR (low-density lipoprotein receptor) in the liver is the major determinant of LDL-cholesterol levels in human plasma. The discovery of genes that regulate the activity of LDLR helps to identify pathomechanisms of hypercholesterolemia and novel therapeutic targets against atherosclerotic cardiovascular disease. We performed a genome-wide RNA interference screen for genes limiting the uptake of fluorescent LDL into Huh-7 hepatocarcinoma cells. Top hit genes were validated by in vitro experiments as well as analyses of data sets on gene expression and variants in human populations. The knockdown of 54 genes significantly inhibited LDL uptake. Fifteen of them encode for components or interactors of the U2-spliceosome. Knocking down any one of 11 out of 15 genes resulted in the selective retention of intron 3 of LDLR. The translated LDLR fragment lacks 88% of the full length LDLR and is detectable neither in nontransfected cells nor in human plasma. The hepatic expression of the intron 3 retention transcript is increased in nonalcoholic fatty liver disease as well as after bariatric surgery. Its expression in blood cells correlates with LDL-cholesterol and age. Single nucleotide polymorphisms and 3 rare variants of one spliceosome gene, RBM25, are associated with LDL-cholesterol in the population and familial hypercholesterolemia, respectively. Compared with overexpression of wild-type RBM25, overexpression of the 3 rare RBM25 mutants in Huh-7 cells led to lower LDL uptake. We identified a novel mechanism of posttranscriptional regulation of LDLR activity in humans and associations of genetic variants of RBM25 with LDL-cholesterol levels.

Recent dynamic studies of the metabolism of atherogenic lipoproteins: elucidating the mode of action of new therapies.

LDL, triglyceride-rich lipoprotein (TRL) and lipoprotein(a) [Lp(a)] particles are the key atherogenic lipoproteins. Deranged metabolism of these lipoproteins accounts for a spectrum of clinically important dyslipidemias, such as FH, elevated Lp(a) and diabetic dyslipidemia. We review the findings from recent dynamic and tracer studies that have contributed to expanding knowledge in this field. Deficiency in LDL receptor activity does not only impair the catabolism of LDL-apoB-100 in FH, but also induces hepatic overproduction and decreases catabolism of TRLs. Patients with elevated Lp(a) are characterized by increased hepatic secretion of Lp(a) particles. Elevation of TRLs in diabetes is partly mediated by increased production of apoB-48 and apoC-III, and impaired clearance of apoB-48 in the postprandial state. Tracer kinetic studies show that proprotein convertase subtilisin/kexin type 9 mAbs alone or in combination with statin can increase the catabolism and decrease production of LDL and Lp(a) particles. By contrast, angiopoietin-like protein 3 inhibitors (e.g. evinacumab) reduce VLDL production and increase LDL clearance in FH. Glucagon-like peptide-1 receptor agonists can improve diabetic dyslipidemia by increasing the catabolism of apoB-48 and decreasing the production of apoB-48 and apoC-III. Dynamic studies of the metabolism of atherogenic lipoproteins provide new insight into the nature of dyslipidemias and point to how new therapies with complementary modes of action may have maximal clinical impact.

Characterization of Two Variants at Met 1 of the Human LDLR Gene Encoding the Same Amino Acid but Causing Different Functional Phenotypes.

Familial hypercholesterolemia (FH) is the most common genetic disorder of lipid metabolism, characterized by increased levels of total and LDL plasma cholesterol, which leads to premature atherosclerosis and coronary heart disease. FH phenotype has considerable genetic heterogeneity and phenotypic variability, depending on LDL receptor activity and lifestyle. To improve diagnosis and patient management, here, we characterized two single nucleotide missense substitutions at Methionine 1 of the human LDLR gene (c.1A>T/p.(Met1Leu) and c.1A>C/p.(Met1Leu)). We used a combination of Western blot, flow cytometry, and luciferase assays to determine the effects of both variants on the expression, activity, and synthesis of LDLR. Our data show that both variants can mediate translation initiation, although the expression of variant c.1A>T is very low. Both variants are in the translation initiation codon and codify for the same amino acid p.(Met1Leu), yet they lead to different levels of impairment on LDLR expression and activity, corroborating different efficiencies of the translation initiation at these non-canonical initiation codons. The functional data of these variants allowed for an improved American College of Medical Genetics (ACMG) classification for both variants, which can allow a more personalized choice of the lipid-lowering treatment and dyslipidemia management, ultimately improving patients’ prognosis.

P–658 Lovastatin promotes the expression of LDL receptor and enhances E2 production in the cumulus cells

Abstract Study question Lovastatin enhanced E2 productive ratios in the cumulus cells through promoted expression of Low-density lipoprotein receptor (LDLR). Summary answer Lovastatin up-regulated gene expression of LDLR in the CCs. And the high expression of LDLR promoted E2 productive ratios from CCs. What is known already We already reported that the up-regulation of LDLR correlated with clinical pregnancy. Therefore, we found lovastatin as an up-regulator of LDLR expression of clinical pregnancy. Study design, size, duration This is an expended study of LDLR to enhance steroidogenesis regarding the effect of lovastatin in the CCs. The collection of human cumulus cells was approved by the Institutional Research and Ethical Committees of CHA University (approval number: 1044308–201611-BR–027–04) from January to December 2019. The CCs were collected from 12 patients with normal ovarian response after oocyte denudation for ICSI. Participants/materials, setting, methods We studied whether lovastatin has up-regulated LDLR expression in human CCs. Cumulus cells were collected from patients with young (∼ 36) and old aged patients (37 ∼). After culturing human CCs, they were treated lovastatin for one day. The concentration of E2 in culture medium was measured using Chemiluminescence immunoassay. The mRNA isolated from CCs was analyzed gene expression level through real time-PCR. Main results and the role of chance The concentration of E2 was significantly increased in the culture medium treated with lovastatin. The CCs treated with lovastatin increased the expression of LDLR and StAR which are components of the steroidogenesis pathway. Limitations, reasons for caution We have found that the role of lovastatin promotes the E2 production by increasing the ldlr gene of CCs. Therefore, further investigations aimed at lovastatin effect on human oocytes embryo whether enhanced quality of oocytes or not. Wider implications of the findings: Previous data show that high activation of LDLR and StAR was associated with embryo quality and clinical pregnancy in infertile women. Our data suggest that lovastatin is stimulated LDLR expression to enhanced pregnancy ratios of IVF patients. Trial registration number none

A comprehensive account of insulin and LDL receptor activity over the years: A highlight on their signaling and functional role.

Insulin receptor (IR) was discovered in 1970. Shortcomings in IR transcribed signals were found pro-diabetic, which could also inter-relate obesity and atherosclerosis in a time-dependent manner. Low-density lipoprotein receptor (LDLR) was discovered in 1974. Later studies showed that insulin could modulate LDLR expression and activity. Repression of LDLR transcription in the absence or inactivity of insulin showed a direct cause of atherosclerosis. Leptin receptor (OB-R) was found in 1995 and its resistance became responsible for developing obesity. The three interlinked pathologies namely, diabetes, atherosclerosis, and obesity were later on marked as metabolic syndrome-X (MSX). In 2012, the IR-LDLR inter-association was identified. In 2019, the proficiency of signal transmission from this IR-LDLR receptor complex was reported. LDLR was found to mimic IR-generated signaling path when it remains bound to IR in IR-DLR interlocked state. This was the first time LDLR was found sending messages besides its LDL-clearing activity from blood vessels.

Identification of neolignans with PCSK9 downregulatory and LDLR upregulatory activities from Penthorum chinense and the potential in cholesterol uptake by transcriptional regulation of LDLR via SREBP2

Ethnopharmacological relevancePenthorum chinense has been used in East Asia for the treatment of cholecystitis, infectious hepatitis, jaundice and to treat liver problems. Recent evidences provided the potential for the clinical use of P. chinense in the treatment of metabolic disease.Aim of the study: Based on the traditional use and recent evidences, we investigated the effects of constituents from P. chinense with modulation on proprotein convertase subtilisin/kexin type 9 (PCSK9) and low-density lipoprotein receptor (LDLR) expression, and the effect of the most active substance on cholesterol uptake, and genes relevant to lipid metabolism. Materials and methodsThe isolation of compounds from the BuOH-soluble extract of 80% methanol extract of P. chinense was conducted using chromatographic methods and the structures were established by interpreting spectroscopic data. Quantitative real time-PCR, and Western blot analysis were performed to monitor the regulatory activity on PCSK9 and LDLR expression. PCSK9-LDLR binding interaction was also tested. The cholesterol uptake in hepatocyte was measured using 1,1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine perchlorate (DiI)-labeled LDL cholesterol. Additionally, gene network analysis of LDLR and responses of its target proteins were carried out to discover genes germane to the effect of active compound on HepG2 cells. Moreover, we performed protein-protein interaction analysis via String and constructed the compound target network using Cytoscape. ResultsTwo new neolignans and 37 known compounds were characterized from P. chinense. Of the isolated compounds, (7′E,8S)-2′,4,8-trihydroxy-3-methoxy-2,4′-epoxy-8,5′-neolign-7′-en-7-one (3), penthorin A (4) and methyl gallate (25) were found to suppress PCSK9 mRNA expression with IC50 values of 5.13, 15.56 and 11.66 μM, respectively. However, all the isolated compounds were found to be inactive in PCSK9-LDLR interaction assay. Additionally, a dibenzoxepine-type lignan analog, (7′E,8S)-2′,4,8-trihydroxy-3-methoxy-2,4′-epoxy-8,5′-neolign-7′-en-7-one (3) demonstrated to upregulate LDLR mRNA and protein expression via transcriptional factor sterol regulatory element-binding protein 2 (SREBP2). Furthermore, (7′E,8S)-2′,4,8-trihydroxy-3-methoxy-2,4′-epoxy-8,5′-neolign-7′-en-7-one (3) increase the LDL-cholesterol uptake in DiI-LDL assay. Conclusion(7′E,8S)-2′,4,8-trihydroxy-3-methoxy-2,4′-epoxy-8,5′-neolign-7′-en-7-one (3) seemed to increase potentially cholesterol uptake via the downregulation of PCSK9 and the activation of LDLR in hepatocytes. Moreover, SREBP2 was found to play an important role in regulation of PCSK9 and LDLR by (7′E,8S)-2′,4,8-trihydroxy-3-methoxy-2,4′-epoxy-8,5′-neolign-7′-en-7-one.

Anti-PCSK 9 antibodies increase the ratios of the brain-specific oxysterol 24S-hydroxycholesterol to cholesterol and to 27-hydroxycholesterol in the serum.

The serum ratios of the brain-specific oxysterol 24S-hydroxycholesterol (24S-OHC) to cholesterol and to 27-OHC reflect brain cholesterol turnover. We studied the effect of proprotein convertase subtilisin/kexin type 9 monoclonal antibodies (PCSK9ab) that enhance low-density lipoprotein receptor activity on serum cholesterol and oxysterol concentrations. Twenty-eight hypercholesterolaemic patients (15 males and 13 females) responding insufficiently to maximally tolerated statin and/or ezetimibe therapy were additionally subcutanously treated biweekly with either the PCSK9ab alirocumab (150 mg, n =13) or evolocumab (140 mg, n =15). Fasting serum cholesterol was measured by gas chromatography and the oxysterols 24S-OHC and 27-OHC using gas chromatography-mass spectrometry before, after 1-month (n =28) and after 3-month (n =13) treatment. As expected, PCSK9ab treatment lowered serum cholesterol and oxysterol levels after 1 month. The serum ratio of 24S-OHC to cholesterol increased after 1 month by 17 ± 28% (mean ± standard deviation; 95% confidence interval [CI]: 5.8 to 28%; P< .01) and 24S-OHC to 27-OHC by 15 ± 39% (95% CI: 0.2 to 30%; P< .01). Within 3 months, 24S-OHC to cholesterol increased by 2.8 μg g-1 mo-1 (95% CI: 2.1 to 3.6; P< .01) and 24S-OHC to 27-OHC by 0.019 mo-1 (95% CI: 0.007 to 0.032; P< .01). The serum ratios of 24S-OHC to cholesterol and to 27-OHC increased after treatment with PCSK9ab. We hypothesize that this is caused by a reduced entrance of 27-OHC into the brain, increased synthesis of brain cholesterol, increased production of 24S-OHC and its secretion across the blood-brain barrier.

Inhibition of angiopoietin-like 3 for the management of severe hypercholesterolemia.

Despite the therapeutic advances for patients with severe hypercholesterolemia, particularly those with homozygous familial hypercholesterolemia (HoFH), most patients are unable to achieve target low-density lipoprotein cholesterol (LDL-C) levels with the current available standard lipid-lowering therapy (LLT). We review the role of angiopoietin-like 3 (ANGPTL3) inhibition as an additional therapeutic option for severe hypercholesterolemia, particularly HoFH. Evinacumab is a monoclonal antibody against ANGPTL3, and reduces LDL-C independent of LDL-receptor activity. ANGPTL3 inhibitors are effective in lowering LDL-C in patients with FH, with a 50% reduction in LDL-C in those with HoFH. Longer-term efficacy and safety have been demonstrated with reductions in LDL-C maintained following 48 weeks of therapy. Gene silencing strategies directed against ANGPTL3 include antisense oligonucleotide and small-interfering ribonucleic acid (siRNA). ARO-ANG3 is a siRNA directed against ANGPTL3 messenger ribonucleic acid and is associated with up to a 42% reduction in LDL-C. With the promise of these emerging novel therapeutics directed against ANGPTL3 on the horizon, achieving acceptable target LDL-C levels in HoFH without the need for lipoprotein apheresis may finally be a realistic goal and we can anticipate a decrease in cardiovascular morbidity and mortality in these difficult to treat patients.

Role of PCSK9 Inhibitors in Patients with Familial Hypercholesterolemia.

Patients with familial hypercholesterolemia (FH) are at high or very high risk for cardiovascular disease. Those with heterozygous FH (HeFH) often do not reach low-density lipoprotein cholesterol (LDL-C) targets with statin and ezetimibe therapy, and those with homozygous FH (HoFH) usually require additional lipid-modifying therapies. Drugs that inhibit proprotein convertase subtilisin/kexin type 9 (PCSK9) offer a novel approach to reduce LDL-C. The monoclonal antibodies, alirocumab and evolocumab, given by subcutaneous injection every 2 or 4 weeks produce reductions in LDL-C of 50% to 60% in patients with HeFH, allowing many of them to achieve their LDL-C goals. Patients with HoFH show a reduced and more variable LDL-C response, which appears to depend on residual LDL receptor activity, and those with receptor-negative mutations may show no response. Inclisiran is a long-acting small interfering RNA therapeutic agent that inhibits the synthesis of PCSK9. Subcutaneous doses of 300 mg can reduce LDL-C by more than 50% for at least 6 months and the responses in HeFH and HoFH patients are similar to those achieved with monoclonal antibodies. These PCSK9 inhibitors are generally well tolerated and they provide a new opportunity for effective treatment for the majority of patients with FH.

A prospective study of the relationships between change in body composition and cardiovascular risk factors across the menopause.

Objective:Menopause increases the risk of cardiovascular disease (CVD) which in part has been attributed to the rise in cholesterol and blood pressure (BP). This study examined the hypothesis that menopausal changes in body composition and regional fat depots relate to the change in CVD risk factors.Methods:A prospective recall study was designed to capture premenopausal women to be re-examined soon after menopause. A total of 97 women from the Oxford Biobank underwent dual x-ray absorptiometry, blood biochemistry, and BP readings pre- and postmenopause.Results:Despite minimal changes in body weight over the 5.1 ± 0.9 year follow-up period, there was an increase in total fat mass and a decline in lean mass, where the proportional change of regional fat mass was the greatest for the visceral fat depot (+22%, P < 0.01). Plasma ApoB (+12%, P < 0.01) and C-reactive protein (+45%, P < 0.01) increased as did systolic (+7%, P < 0.001) and diastolic BP (+5%, P < 0.001). Plasma nonesterified fatty acids decreased (−20%, P < 0.05) which may reflect on a change in adipose tissue function across the menopause. PCSK-9 decreased (−26%, P < 0.01) which suggests a compensation for the postmenopausal reduction in low-density lipoprotein receptor activity. Using multilinear regression analyses the changes in ApoB and diastolic BP were associated with visceral fat mass change, but this association was lost when adjusted for total fat mass change.Conclusion:The increase in CVD risk factor burden across menopause may not be driven by changes in body composition, rather by functional changes in end organs such as adipose tissue and liver.

Homozygous Familial Hypercholesterolemia.

Familial hypercholesterolemia (FH) is an inherited disorder with retarded clearance of plasma LDL caused by mutations of the genes involved in the LDL receptor-mediated pathway and most of them exhibit autosomal dominant inheritance. Homozygotes of FH (HoFH) may have plasma LDL-C levels, which are at least twice as high as those of heterozygous FH (HeFH) and therefore four times higher than normal levels. Prevalence of HoFH had been estimated as 1 in 1,000,000 before but more recent genetic analysis surveys predict 1 in 170,000 to 300,000. Since LDL receptor activity is severely impaired, HoFH patients do not or very poorly respond to medications to enhance activity, such as statins, and have a poorer prognosis compared to HeFH. HoFH should therefore be clinically distinguished from HeFH. Thorough family studies and genetic analysis are recommended for their accurate diagnosis.Fatal cardiovascular complications could develop even in the first decade of life for HoFH, so aggressive lipid-lowering therapy should be initiated as early as possible. Direct removal of plasma LDL by lipoprotein apheresis has been the principal measure for these patients. However, this treatment alone may not achieve stable LDL-C target levels and combination with drugs should be considered. The lipid-lowering effects of statins and PCSK9 inhibitors substantially vary depending on the remaining LDL receptor activity of individual patients. On the other hand, the action an MTP inhibitor is independent of LDL receptor activity, and it is effective in most HoFH cases.This review summarizes the key clinical issues of HoFH as well as insurance coverage available under the Japanese public healthcare system.

Novel therapies for familial hypercholesterolemia.

Familial hypercholesterolemia is a genetic disorder of defective clearance and subsequent increase in serum LDL cholesterol (LDL-C) with a resultant increased risk of premature atherosclerotic cardiovascular disease. Despite treatment with traditional lipid-lowering therapies (LLT), most patients with familial hypercholesterolemia are unable to achieve target LDL-C. We review current and future novel therapeutic options available for familial hypercholesterolemia. The use of proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors are effective in lowering LDL-C in patients with familial hypercholesterolemia, with a reduction in LDL-C of 60% in heterozygous familial hypercholesterolemia (HeFH) and up to 35% in homozygous familial hypercholesterolemia (HoFH). Inclisiran, another novel agent, is a small-interfering ribonucleic acid that reduces hepatic production of PCSK9 to provide a prolonged and sustained reduction in LDL-C of nearly 50% in HeFH. However, both agents require LDL receptor (LDLR) activity. Evinacumab, a novel monoclonal antibody against angiopoetin-like 3 (ANGPTL3), reduces LDL-C by 50% independent of LDLR activity. Achieving a target LDL-C in familial hypercholesterolemia can be challenging with standard LLT; however, novel therapeutic modalities show remarkable reductions in LDL-C allowing nearly all patients with HeFH and a significant proportion of patients with HoFH to achieve acceptable LDL-C levels.

The efficacy and safety of evinacumab in homozygous familial hypercholesterolaemia (HoFH) patients with little to no low-density lipoprotein receptor (LDLR) activity

The efficacy and safety of evinacumab in homozygous familial hypercholesterolaemia (HoFH) patients with little to no low-density lipoprotein receptor (LDLR) activity

GPR146 Deficiency protects against hypercholesterolemia and atherosclerosis

Short summary: Deficiency in the orphan G protein coupled receptor 146 (GPR146) decreases blood lipid levels and protects against atherosclerosis in mice, independent of LDL receptor activity.

Virgin Olive Oil Extracts Reduce Oxidative Stress and Modulate Cholesterol Metabolism: Comparison between Oils Obtained with Traditional and Innovative Processes.

This study was aimed at demonstrating the substantial equivalence of two extra virgin olive oil samples extracted from the same batch of Coratina olives with (OMU) or without (OMN) using ultrasound technology, by performing chemical, biochemical, and cellular investigations. The volatile organic compounds compositions and phenolic profiles were very similar, showing that, while increasing the extraction yields, the innovative process does not change these features. The antioxidant and hypocholesterolemic activities of the extra virgin olive oil (EVOO) phenol extracts were also preserved, since OMU and OMN had equivalent abilities to scavenge the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radicals in vitro and to protect HepG2 cells from oxidative stress induced by H2O2, reducing intracellular reactive oxygen species (ROS) and lipid peroxidation levels. In addition, by inhibiting 3-hydroxy-3-methylglutarylcoenzyme a reductase, both samples modulated the low-density lipoprotein receptor (LDLR) pathway leading to increased LDLR protein levels and activity.

Loss-of-function mutation of PCSK9 as a protective factor in the clinical expression of familial hypercholesterolemia

Rationale:Proprotein convertase subtilisin/kexin 9 or PCSK9 is a protein whose main function is to regulate the number of low-density lipoprotein receptors (LDLR) present on the cell surface. Loss-of-function mutations in PCSK9 have been related to low LDL-cholesterol levels and a decrease in the risk of cardiovascular events.Patient concerns:We present the case of a 27-year-old woman, offspring of a patient with familial homozygous hypercholesterolemia, who presented with mild-moderate hypercholesterolemia.Diagnosis:Genetic analysis was performed by next generation sequencing using a customized panel of 198 genes. Sanger sequencing was used to confirm the presence of the variants of interest. The genetic analysis showed a pathogenic heterozygous mutation in LDLR [exon 6:c.902A>G:p(Asp301Gly)], as well as a loss-of-function heterozygous variant in PCSK9 [exon1:c.137 G>T:p.(Arg46Leu)]. The genetic analysis of the index case's mother revealed compound heterozygosity for 2 different mutations in LDLR [c.902A>G:p.(Asp301Gly); c.1646G>T:p.(Gly549Val)] in exon 6 and in exon 11, respectively, and the same loss-of-function variant in PCSK9 that had been found in her daughter [(PCSK9:exon1:c.137G>T:p.(Arg46Leu)]. The maternal grandfather of the index case presented the same genetic variants as his granddaughter.Interventions:The index case did not receive any specific treatment for hypercholesterolemia. The loss-of-function variant in PCSK9 protected her from higher LDL-cholesterol levels, provided she kept partial activity of the LDLR. In her mother, instead, a PCSK9 inhibitor was tried but failed to achieve lipid control. The reason for this may be the complete absence in LDL receptor activity. LDL apheresis was started afterwards, resulting in adequate lipid level control.Outcomes:To the date, the index case has achieved to maintain adequate total and LDL-cholesterol levels without any other intervention. She has had no known cardiovascular complication.Lessons:Loss-of-function mutations in PCSK9 could protect from developing more severe forms of hypercholesterolemia. The finding of these mutations (LDLR-PCSK9) in three consecutive generations could imply an adaptive mechanism against the development of hypercholesterolemia.

Evinacumab for Homozygous Familial Hypercholesterolemia

BackgroundHomozygous familial hypercholesterolemia is characterized by premature cardiovascular disease caused by markedly elevated levels of low-density lipoprotein (LDL) cholesterol. This disorder is associated with genetic variants that result in virtually absent (null–null) or impaired (non-null) LDL-receptor activity. Loss-of-function variants in the gene encoding angiopoietin-like 3 (ANGPTL3) are associated with hypolipidemia and protection against atherosclerotic cardiovascular disease. Evinacumab, a monoclonal antibody against ANGPTL3, has shown potential benefit in patients with homozygous familial hypercholesterolemia.MethodsIn this double-blind, placebo-controlled, phase 3 trial, we randomly assigned in a 2:1 ratio 65 patients with homozygous familial hypercholesterolemia who were receiving stable lipid-lowering therapy to receive an intravenous infusion of evinacumab (at a dose of 15 mg per kilogram of body weight) every 4 weeks or placebo. The primary outcome was the percent change from baseline in the LDL cholesterol level at week 24.ResultsThe mean baseline LDL cholesterol level in the two groups was 255.1 mg per deciliter, despite the receipt of maximum doses of background lipid-lowering therapy. At week 24, patients in the evinacumab group had a relative reduction from baseline in the LDL cholesterol level of 47.1%, as compared with an increase of 1.9% in the placebo group, for a between-group least-squares mean difference of –49.0 percentage points (95% confidence interval [CI], –65.0 to –33.1; P<0.001); the between-group least-squares mean absolute difference in the LDL cholesterol level was –132.1 mg per deciliter (95% CI, –175.3 to –88.9; P<0.001). The LDL cholesterol level was lower in the evinacumab group than in the placebo group in patients with null–null variants (–43.4% vs. +16.2%) and in those with non-null variants (–49.1% vs. –3.8%). Adverse events were similar in the two groups.ConclusionsIn patients with homozygous familial hypercholesterolemia receiving maximum doses of lipid-lowering therapy, the reduction from baseline in the LDL cholesterol level in the evinacumab group, as compared with the small increase in the placebo group, resulted in a between-group difference of 49.0 percentage points at 24 weeks. (Funded by Regeneron Pharmaceuticals; ELIPSE HoFH ClinicalTrials.gov number, NCT03399786.)