Targeting PCSK9 for hypercholesterolemia

BCG-trained macrophages couple LDLR upregulation to type I IFN responses and antiviral immunity

Trained immunity refers to memory-like responses of innate immune cells when they re-encounter pathogenic stimuli. Bacillus Calmette-Guérin (BCG) vaccination implies enhanced antiviral immunity, whereas the underlying mechanisms remain unclear. Herein, we have uncovered elevated expression of low-density lipoprotein receptor (LDLR) on BCG-trained macrophages with robust type I interferon (IFNI) production and antiviral effects both in vivo and in vitro. Consequently, cholesterol is accumulated in BCG-trained macrophages, leading to the augmentation of NFE2L1 expression and the formation of NFE2L1/IRAK1/TRIM25 complex where TRIM25 mediates IRAK1 K63 polyubiquitination to exaggerate IFNI responses in an RIG-I-dependent manner. We have also observed LDLR+ macrophages displaying heightened IFNI responses in BCG-treated human macrophages. To antagonize LDLR degradation by PCSK9 inhibitors increases IFNI responses in the macrophages and accelerated viral clearance. Our study thus couples LDLR upregulation to antiviral activity in BCG-trained macrophages, making commercial PCSK9 inhibitors potential antiviral indications in clinic.

The Role of Non-Statin Lipid Lowering Therapies to Reduce ASCVD Events in Primary Prevention

PURPOSE OF REVIEW

Atherosclerotic cardiovascular disease (ASCVD) remains a leading global health challenge, with low-density lipoprotein (LDL) cholesterol a pivotal risk factor. While statins are cornerstone therapy for lowering LDL cholesterol, many high-risk primary prevention patients are unable to tolerate statin therapy and do not achieve their guideline directed LDL cholesterol goal. For these patients, non-statin therapies offer complementary and alternative approaches to LDL cholesterol reduction.

RECENT FINDINGS

Recent advancements in non-statin therapies have expanded the options available to clinicians to lower LDL cholesterol in high-risk primary prevention patients. Yet these medications are often under-utilized in clinical practice. Observational studies, Mendelian randomization studies, and randomized clinical trials support the role of non-statin LDL cholesterol lowering therapies in the primary prevention of ASCVD. This review summarizes the evidence supporting their use for the primary prevention of ASCVD and offers practical suggestions as to how clinicians can integrate these medications into their clinical practice.

Neuronal PCSK9 regulates cognitive performances via the modulation of ApoER2 synaptic localization

PCSK9 promotes the degradation of the low-density lipoprotein receptors and its inhibition by monoclonal antibodies or gene silencing approaches results in the reduction of plasma cholesterol levels coupled to that of cardiovascular events. Notably, while the liver is the primary source of circulating PCSK9, this protein is also abundantly expressed in the brain. However, its specific functions in the brain remain poorly understood. Here, we demonstrate that neuron-specific PCSK9 knockout mice exhibit impaired cognitive function, driven by alterations in hippocampal synapse morphology and synaptic plasticity mechanisms, coupled to spatial memory deficits. Among PCSK9 targets, we identified ApoER2 as the primary mediator of PCSK9-dependent effects on synaptic function. In neuronal cultures, PCSK9 downregulation affects ApoER2 synaptic membrane localization and lipid droplets abundance. In conclusion, our results highlight the critical role of neuronal PCSK9 in modulating synaptic ApoER2 and reveal the detrimental effects of its deficiency on synaptic function and cognitive performance. Our results shed light on the complex biology of PCSK9, crucial for evaluating side effects of PCSK9 inhibition and for developing new therapies targeting PCSK9 for brain disorders.

Analysis of Inclisiran in the US FDA Adverse Event Reporting System (FAERS): a focus on overall patient population and sex-specific subgroups

BACKGROUND

Our study aimed to identify inclisiran-related adverse events(AEs) for primary hypercholesterolemia and arteriosclerotic cardiovascular disease(ASCVD) from the US FDA Adverse Event Reporting System (FAERS) database, analyzing its links to AEs in the overall patient population and sex-specific subgroups to improve medication safety.

METHODS

We analyzed inclisiran-related AEs signals by using statistical methods like Reporting Odds Ratio (ROR), Proportional Reporting Ratios (PRR), Bayesian Confidence Propagation Neural Network (BCPNN), and Multi-item Gamma-Poisson Shrinker (MGPS).

RESULTS

Analyzing 2,400 AE reports with inclisiran as the primary suspected drug in the FAERS database, we identified 70 AE signals over 13 organ systems using the above four methods. Notable findings were strong signals for systemic diseases and various reactions at the site of administration (ROR 1.49, 95% CI 1.41-1.57), and various musculoskeletal and connective tissue diseases (ROR 4.07, 95% CI 3.83-4.03) in overall and gender-specific populations. Myalgia, a new ADE signal not in the drug insert, was a top signal by intensity and frequency (ROR 14.76, 95% CI 12.84-16.98).

CONCLUSION

Our study revealed the strongest AE signals associated with inclisiran in both the overall population and gender subgroups, highlighting potential risks in clinical medication use and guiding balanced clinical decision-making.

MiR-99a-5p up-regulates LDLR and functionally enhances LDL-C uptake via suppressing PCSK9 expression in human hepatocytes

Background

MicroRNAs (miRs/miRNAs) play pivotal roles in modulating cholesterol homeostasis. Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to low-density lipoprotein receptor (LDLR) at the surface of hepatocytes and accelerates its degradation in lysosomes, thereby impairing the clearance of circulating low-density lipoprotein cholesterol (LDL-C) from plasma. Thus, suppressing PCSK9 expression level has become an effective approach for treating hypercholesterolemia. Here, we sought to identify novel miRNAs that inhibit PCSK9 expression.

Methods

By in silico analyses, miR-99a-5p was predicted to bind to human PCSK9 mRNA. Following transfection of miR-99a-5p or anti-miR-99a-5p in human and mouse hepatocytes, qRT-PCR, Western blot, immunofluorescence, ELISA, flow cytometry, LDL-C uptake, and cellular cholesterol measurement were performed.

Results

miR-99a-5p overexpression potently inhibited PCSK9 expression, thereby up-regulating LDLR, functionally enhancing LDL-C uptake and increasing intracellular cholesterol levels in human, but not in mouse, cells. Conversely, anti-miR-99a-5p upregulates PCSK9, leading to a reduction in LDLR, attenuation of LDL-C uptake, and a decrease in the intracellular cholesterol levels of human hepatocytes. Furthermore, miR-99a-5p was shown to bind to the predicted target site "UACGGGU" in the 3'-UTR of human PCSK9 mRNA via a luciferase reporter assay in combination with site-directed mutagenesis.

Conclusion

MiR-99a-5p potently downregulates the expression of PCSK9 by directly interacting with a target site in the human PCSK9 3'-UTR, thereby up-regulating LDLR and functionally enhancing LDL-C uptake in human hepatocytes. MiR-99a-5p could serve as an inhibitor of PCSK9 for treating hypercholesterolemia to inhibit atherosclerosis.

2023 China Guidelines for Lipid Management

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death among urban and rural residents in China, and elevated low-density lipoprotein cholesterol (LDL-C) is a risk factor for ASCVD. Considering the increasing burden of ASCVD, lipid management is of the utmost importance. In recent years, research on blood lipids has made breakthroughs around the world, hence a revision of China guidelines for lipid management is imperative, especially since the target lipid levels in the general population vary in respect to the risk of ASCVD. The level of LDL-C, which can be regarded as appropriate in a population without frisk factors, can be considered abnormal in people at high risk of developing ASCVD. As a result, the "Guidelines for the prevention and treatment of dyslipidemia" were adapted into the "China Guidelines for Lipid Management" (henceforth referred to as the new guidelines) by an Experts' committee after careful deliberation. The new guidelines still recommend LDL-C as the primary target for lipid control, with CVD risk stratification to determine its target value. These guidelines recommend that moderate intensity statin therapy in adjunct with a heart-healthy lifestyle, be used as an initial line of treatment, followed by cholesterol absorption inhibitors or/and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, as necessary. The new guidelines provide guidance for lipid management across various age groups, from children to the elderly. The aim of these guidelines is to comprehensively improve the management of lipids and promote the prevention and treatment of ASCVD by guiding clinical practice.

2023 Chinese guideline for lipid management

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death among urban and rural residents in China, and elevated low-density lipoprotein cholesterol (LDL-C) is a risk factor for ASCVD. Considering the increasing burden of ASCVD, lipid management is of the utmost importance. In recent years, research on blood lipids has made breakthroughs around the world, hence a revision of Chinese guideline for lipid management is imperative, especially since the target lipid levels in the general population vary in respect to the risk of ASCVD. The level of LDL-C, which can be regarded as appropriate in a population without frisk factors, can be considered abnormal in people at high risk of developing ASCVD. As a result, the "Guidelines for the prevention and treatment of dyslipidemia" were adapted into the "Chinese guideline for Lipid Management" (henceforth referred to as the new guidelines) by an Experts' committee after careful deliberation. The new guidelines still recommend LDL-C as the primary target for lipid control, with cardiovascular disease (CVD) risk stratification to determine its target value. These guidelines recommend that moderate intensity statin therapy in adjunct with a heart-healthy lifestyle, be used as an initial line of treatment, followed by cholesterol absorption inhibitors or/and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, as necessary. The new guidelines provide guidance for lipid management across various age groups, from children to the elderly. The aim of these guidelines is to comprehensively improve the management of lipids and promote the prevention and treatment of ASCVD by guiding clinical practice.

A Jordanian Multidisciplinary Consensus Statement on the Management of Dyslipidemia

Atherosclerotic cardiovascular disease (ASCVD) is the primary contributor to global mortality rates, which significantly escalates healthcare expenditures. Risk factors for ASCVD (including dyslipidemia) frequently present in clusters rather than separately. Addressing these risk factors is crucial in the early initiation of a comprehensive management plan that involves both lifestyle modifications and pharmacotherapy to reduce the impact of ASCVD. A team of Jordanian professionals from various medical organizations and institutes took the initiative to create a set of guidelines for dyslipidemia screening and therapy. A detailed, comprehensive literature review was undertaken utilizing several databases and keywords. This consensus statement provides recommendations for dyslipidemia management in Jordanians on several issues including cardiovascular risk estimation, screening eligibility, risk categories, treatment goals, lifestyle changes, and statin and non-statin therapies. It is recommended that all Jordanian individuals aged 20 years old or older undergo lipid profile testing. This should be followed by determining the level of cardiovascular risk depending on the presence or absence of ASCVD and cardiovascular risk factors, eligibility for lipid-lowering therapy, and the target low-density cholesterol serum level to be achieved. In conclusion, prioritizing the management of dyslipidemia is of the utmost importance in improving public health and reducing the burden of cardiovascular diseases.

Cholesterol Redistribution in Pancreatic β-Cells: A Flexible Path to Regulate Insulin Secretion

Pancreatic β-cells, by secreting insulin, play a key role in the control of glucose homeostasis, and their dysfunction is the basis of diabetes development. The metabolic milieu created by high blood glucose and lipids is known to play a role in this process. In the last decades, cholesterol has attracted significant attention, not only because it critically controls β-cell function but also because it is the target of lipid-lowering therapies proposed for preventing the cardiovascular complications in diabetes. Despite the remarkable progress, understanding the molecular mechanisms responsible for cholesterol-mediated β-cell function remains an open and attractive area of investigation. Studies indicate that β-cells not only regulate the total cholesterol level but also its redistribution within organelles, a process mediated by vesicular and non-vesicular transport. The aim of this review is to summarize the most current view of how cholesterol homeostasis is maintained in pancreatic β-cells and to provide new insights on the mechanisms by which cholesterol is dynamically distributed among organelles to preserve their functionality. While cholesterol may affect virtually any activity of the β-cell, the intent of this review is to focus on early steps of insulin synthesis and secretion, an area still largely unexplored.

Pharmacotherapy of the Lipid-Lowering Drugs: Update on Efficacy and Risk

Lipid-lowering drugs are widely used for the prevention and cure of cardiovascular diseases (CVD) [...].

Pancreatic PCSK9 controls the organization of the β-cell secretory pathway via LDLR-cholesterol axis

BACKGROUND

Cholesterol is central to pancreatic β-cell physiology and alterations of its homeostasis contribute to β-cell dysfunction and diabetes. Proper intracellular cholesterol levels are maintained by different mechanisms including uptake via the low-density lipoprotein receptor (LDLR). In the liver, the proprotein convertase subtilisin/kexin type 9 (PCSK9) routes the LDLR to lysosomes for degradation, thus limiting its recycling to the membrane. PCSK9 is also expressed in the pancreas and loss of function mutations of PCSK9 result in higher plasma glucose levels and increased risk of Type 2 diabetes mellitus. Aim of this study was to investigate whether PCSK9 also impacts β-cells function.

METHODS

Pancreas-specific Pcsk9 null mice (Pdx1Cre/Pcsk9 fl/fl) were generated and characterized for glucose tolerance, insulin release and islet morphology. Isolated Pcsk9-deficient islets and clonal β-cells (INS1E) were employed to characterize the molecular mechanisms of PCSK9 action.

RESULTS

Pdx1Cre/Pcsk9 fl/fl mice exhibited normal blood PCSK9 and cholesterol levels but were glucose intolerant and had defective insulin secretion in vivo. Analysis of PCSK9-deficient islets revealed comparable β-cell mass and insulin content but impaired stimulated secretion. Increased proinsulin/insulin ratio, modifications of SNARE proteins expression and decreased stimulated‑calcium dynamics were detected in PCSK9-deficient β-cells. Mechanistically, pancreatic PCSK9 silencing impacts β-cell LDLR expression and cholesterol content, both in vivo and in vitro. The key role of LDLR is confirmed by the demonstration that LDLR downregulation rescued the phenotype.

CONCLUSIONS

These findings establish pancreatic PCSK9 as a novel critical regulator of the functional maturation of the β-cell secretory pathway, via modulation of cholesterol homeostasis.

Impact of conventional lipid-lowering therapy on circulating levels of PCSK9: protocol for a systematic review and meta-analysis of randomised controlled trials

INTRODUCTION

Conventional lipid-lowering agents, including statins, ezetimibe, fibrates, bile acid sequestrants, nicotinic acid, bempedoic acid and Omega-3, are essential to the management of dyslipidaemia. However, these agents have been shown to increase the level of plasma proprotein convertase subtilisin/kexin 9 (PCSK9), a serine protease associated with increased cardiovascular risk. This review aims to investigate the impact of commonly available conventional lipid-lowering agents on circulating PCSK9 levels and lipid profiles.

METHODS AND ANALYSIS

This protocol is conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines. A systematic search will be conducted in the following databases: MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, Web of Science, SCOPUS and ScienceDirect. Additional information will be retrieved from clinical trial registries or from reference list searches. Published and peer-reviewed randomised controlled trials with adults receiving statin, ezetimibe, fibrate, bile acid sequestrant, nicotinic acid, bempedoic acid or Omega-3 monotherapy or in combination for at least 2 weeks, with availability of plasma PCSK9 at the beginning and end of treatment or the net changes in values, will be included. Study selection, data extraction and assessment of the risk of bias will be independently conducted by two investigators. Continuous data will be presented as a standardised mean difference with 95% confidence interval (CI) and dichotomous data as risk ratios with 95% CI. Subgroup analysis and sensitivity analysis will be performed when sufficient studies are included. Publication bias will be assessed with a funnel plot and Egger's test.

ETHICS AND DISSEMINATION

Ethics approval is not required as this review will only include data from published sources. The results will be published in a peer-reviewed journal.

PATIENT AND PUBLIC INVOLVEMENT

No patient or members of the general public are involved.

PROSPERO REGISTRATION NUMBER

CRD42022297942.

mRNA Display Reaches for the Clinic with New PCSK9 Inhibitor

Merck & Co. recently reported one of the first mRNA display-derived clinical candidates in a bioavailable inhibitor of proprotein convertase subtilisin/kexin type 9 (PCSK9). Herein, we discuss the chemical and pharmacological challenges surmounted in bringing this compound to trials and the current outlook for mRNA display-based therapeutic development.

Plasma Levels of Proprotein Convertase Subtilisin/Kexin Type 9 Are Inversely Associated with N-Terminal Pro B-Type Natriuretic Peptide in Older Men and Women

BACKGROUND AND AIMS

Cardiac natriuretic peptides (NPs) exert several metabolic effects, including some on lipid metabolism. Higher NPs levels are likely to be associated with a favorable lipid profile. In in vitro studies, NPs have been found to modulate low-density lipoprotein receptor (LDLR) trafficking by preventing proprotein convertase subtilisin/kexin type 9 (PCSK9) overexpression. The aim of our study is to investigate a possible association between plasma levels of PCSK9 and N-terminal pro B-type natriuretic peptide (NT-proBNP) in vivo.

METHODS

We performed a cross-sectional study on 160 consecutive older male and female patients hospitalized for medical conditions. Patients taking lipid-lowering drugs and patients with an admission diagnosis of acute heart failure were excluded. Fasting blood samples were collected after clinical stabilization of the acute illness, the day before discharge.

RESULTS

The mean age was 87.8 ± 6.4 years with a female prevalence (62.5%). The median NT-proBNP was 2340 (814-5397) pg/mL. The mean plasma PCSK9 was 275.2 ± 113.2 ng/mL. We found an inverse correlation between plasma PCSK9 and NT-proBNP (r = -0.280; p = 0.001). This association was confirmed after taking into account NT-proBNP tertiles (plasma PCSK9 levels: 317.4 ± 123.6 ng/mL in the first tertile, 283.3 ± 101.8 ng/mL in the second tertile, 231.3 ± 99.0 ng/mL in the third tertile, p = 0.001) and even after an adjustment for confounding factors (beta = -0.361, p = 0.001 for ln(NT-proBNP); beta = -0.330, p = 0.001 for NT-proBNP tertiles). The strength of the correlation between plasma PCSK9 and NT-proBNP was likely greater in patients affected by type 2 diabetes mellitus (r = -0.483; p = 0.006) and in male patients (r = -0.431, p = 0.001).

CONCLUSION

The inverse association found between PCSK9 and NT-proBNP plasma levels in our real-life clinical study supports the hypothesis that NPs may play a role in cholesterol metabolism, possibly through an inhibitory action on circulating PCSK9 concentrations, thus increasing the availability of LDLR.

Regulation of cholesterol homeostasis in health and diseases: from mechanisms to targeted therapeutics

Disturbed cholesterol homeostasis plays critical roles in the development of multiple diseases, such as cardiovascular diseases (CVD), neurodegenerative diseases and cancers, particularly the CVD in which the accumulation of lipids (mainly the cholesteryl esters) within macrophage/foam cells underneath the endothelial layer drives the formation of atherosclerotic lesions eventually. More and more studies have shown that lowering cholesterol level, especially low-density lipoprotein cholesterol level, protects cardiovascular system and prevents cardiovascular events effectively. Maintaining cholesterol homeostasis is determined by cholesterol biosynthesis, uptake, efflux, transport, storage, utilization, and/or excretion. All the processes should be precisely controlled by the multiple regulatory pathways. Based on the regulation of cholesterol homeostasis, many interventions have been developed to lower cholesterol by inhibiting cholesterol biosynthesis and uptake or enhancing cholesterol utilization and excretion. Herein, we summarize the historical review and research events, the current understandings of the molecular pathways playing key roles in regulating cholesterol homeostasis, and the cholesterol-lowering interventions in clinics or in preclinical studies as well as new cholesterol-lowering targets and their clinical advances. More importantly, we review and discuss the benefits of those interventions for the treatment of multiple diseases including atherosclerotic cardiovascular diseases, obesity, diabetes, nonalcoholic fatty liver disease, cancer, neurodegenerative diseases, osteoporosis and virus infection.

Inclisiran: How Widely and When Should We Use It?

PURPOSE OF REVIEW

Plasma levels of LDL cholesterol (LDL-C) are causally associated with cardiovascular risk. Reducing LDL-C results in a decreased incidence of cardiovascular events, proportionally to the absolute reduction in LDL-C. The inhibition of proprotein convertase subtilisin kexin 9 (PCSK) is a highly effective and safe approach to reducing LDL-C levels. In this review, we discuss the available data on the efficacy and safety of inclisiran, a siRNA targeting PCSK9 and propose a clinical profile for the patients who can benefit the most from this approach.

RECENT FINDINGS

Inclisiran is a small interfering RNA targeting the mRNA of PCSK9 specifically in the liver, owing to the conjugation with triantennary N-acetylgalactosamine. Randomized clinical trials have shown that inclisiran provides robust and durable reductions of PCSK9 and LDL-C levels, with a dosing schedule of once every 6 months after the initial and 3-month doses. These effects are consistent in different categories of patients, including patients with atherosclerotic cardiovascular disease and/or risk equivalent or patients with heterozygous familial hypercholesterolaemia. Ultimately the administration schedule may improve patients' compliance given also the favourable safety profile of the drug. Completion of ongoing outcome clinical trials will provide information on both the expected clinical benefit and the safety of inclisiran administered for longer.

Effectiveness and safety of proprotein convertase subtilisin/kexin type 9 inhibitors in patients with familial hypercholesterolemia. Our experience in implementing the drug program of the Polish National Health Fund

Introduction

Heterozygous familial hypercholesterolemia (FH) is characterized by an elevated plasma low-density lipoprotein cholesterol (LDL-C) concentration despite intensive statin and ezetimibe therapy, which significantly increases the cardiovascular risk.

Aim

The study evaluated the efficacy and safety of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, alirocumab and evolocumab, in reducing lipids in patients with FH.

Material and methods

This was a single-center analysis of 22 patients diagnosed with FH treated with the PCSK9 inhibitors under the drug program of the National Health Fund. The follow-up interviews and laboratory tests were performed at baseline (22 patients), 3 months (22 patients) and 15 months (9 patients) after the first dose of PCSK9 inhibitors.

Results

The mean (SD) baseline level of the total LDL-C fraction was 4.7 ±1.6 mmol/l in the whole group of patients and was significantly reduced after 3 and 15 months of PCSK9 inhibitors therapy to 1.7 ±1.6 and 1.6 ±1.1 mmol/l, respectively. The average percentage of reduction in LDL-C level was 64.9 ±23.7% after 3 months and 66.9 ±18.4% after 15 months. In comparison with baseline, a significant reduction in total cholesterol was observed at both time points (p <0.0002). There were no adverse cardiovascular events or significant growth in the level of alanine transaminase, creatinine, and creatine kinase throughout the study.

Conclusions

Patients with FH treated with PCSK9 inhibitors achieved a significant reduction of LDL-C and total cholesterol with the safety of this treatment in follow-up.

Targeted Strategy in Lipid-Lowering Therapy

Dyslipidemia is characterized by a diminished lipid profile, including increased level of total cholesterol and low-density lipoprotein cholesterol (LDL-c) and reduced level of high-density lipoprotein cholesterol (HDL-c). Lipid-lowering agents represent an efficient tool for the prevention or reduction of progression of atherosclerosis, coronary heart diseases and metabolic syndrome. Statins, ezetimibe, and recently proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are the most effective and used drugs in clinical lipid-lowering therapy. These drugs are mainly aimed to lower cholesterol levels by different mechanisms of actions. Statins, the agents of the first-line therapy-known as 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors-suppress the liver cholesterol synthesis. Ezetimibe as the second-line therapy can decrease cholesterol by inhibiting cholesterol absorption. Finally, the PCSK9 inhibitors act as an inducer of LDL excretion. In spite of their beneficial lipid-lowering properties, many patients suffer from their serious side effects, route of administration, or unsatisfactory physicochemical characteristics. Clinical demand for dose reduction and the improvement of bioavailability as well as pharmacodynamic and pharmacokinetic profile has resulted in the development of a new targeted therapy that includes nanoparticle carriers, emulsions or vaccination often associated with another more subtle form of administration. Targeted therapy aims to exert a more potent drug profile with lipid-lowering properties either alone or in mutual combination to potentiate their beneficial effects. This review describes the most effective lipid-lowering drugs, their favorable and adverse effects, as well as targeted therapy and alternative treatments to help reduce or prevent atherosclerotic processes and cardiovascular events.

New Treatment Targets and Innovative Lipid-Lowering Therapies in Very-High-Risk Patients with Cardiovascular Disease

The effective and fast reduction of circulating low-density lipoprotein cholesterol (LDL-C) is a cornerstone for secondary prevention of atherosclerotic disease progression. Despite the substantial lipid-lowering effects of the established treatment option with statins and ezetimibe, a significant proportion of very-high-risk patients with cardiovascular disease do not reach the recommended treatment goal of <55 mg/dL (<1.4 mmol/L). Novel lipid-lowering agents, including the proprotein convertase subtilisin/kexin type 9 (PCSK9) antibodies alirocumab and evolocumab, the small interfering ribonucleotide acid (si-RNA) inclisiran, as well as the recently approved bempedoic acid, now complete the current arsenal of LDL-C lowering agents. These innovative therapies have demonstrated promising results in clinical studies. Besides a strong reduction of LDL-C by use of highly effective agents, there is still discussion as to whether a very rapid achievement of the treatment goal should be a new strategic approach in lipid-lowering therapy. In this review, we summarize evidence for the lipid-modifying properties of these novel agents and their safety profiles, and discuss their potential pleiotropic effects beyond LDL-C reduction (if any) as well as their effects on clinical endpoints as cardiovascular mortality. In addition to a treatment strategy of “the lower, the better”, we also discuss the concept of “the earlier, the better”, which may also add to the early clinical benefit of large LDL-C reduction after an acute ischemic event.

Inclisiran inhibits oxidized low-density lipoprotein-induced foam cell formation in Raw264.7 macrophages via activating the PPARγ pathway

Proprotein convertase subtilisin kexin type 9 (PCSK9) is a well-known proprotein convertase that influences foam cell formation and modulates atherosclerosis. Inclisiran is a novel chemosynthetic small interfering RNA that inhibits PCSK9 synthesis. This study aimed to explore the effect of inclisiran on oxidized low-density lipoprotein (ox-LDL)-induced foam cell formation in Raw264.7 macrophages and to investigate the underlying mechanisms. Raw264.7 cells were treated with ox-LDL to induce the formation of macrophage-derived foam cells. Oil Red O staining and high-performance liquid chromatography were performed to detect lipid accumulation and cholesterol levels. Dil-ox-LDL uptake assay, CCK-8, RT-qPCR, and Western blotting analysis were performed to examine ox-LDL uptake, cell viability, and expression of scavenger receptor-related factors. Inclisiran reduced lipid accumulation in ox-LDL-treated macrophages in a dose-dependent manner. Inclisiran significantly inhibited the levels of total cholesterol, free cholesterol, and cholesterol ester in the supernatant of Raw264.7 cells. Inclisiran reduced ox-LDL uptake and increased Raw264.7 cell viability. Meanwhile, inclisiran downregulated the expression of SR-A, LOX-1, and CD36 and upregulated SR-BI, ApoE, and ABCA1. Furthermore, inclisiran increased PPARγ activity and decreased NF-κB activity. An inhibitor of PPARγ (T0070907) reversed the beneficial effects of inclisiran on ox-LDL uptake, NF-κB inactivation, and cytokine expression. In conclusion, these data suggested that inclisiran inhibited the formation of macrophage-derived foam cells by activating the PPARγ pathway.HighlightsInclisiran reduces lipid accumulation in Raw264.7 cells;Inclisiran reduces ox-LDL uptake and increases Raw264.7 cell viability;Inclisiran inhibits foam cell formation by activating the PPARγ pathway.

Associations of pro-protein convertase subtilisin-like kexin type 9, soluble low-density lipoprotein receptor and coronary artery disease: A case-control study

BACKGROUND

Low-density lipoprotein receptor (LDLR) is the primary pathway for removal of cholesterol from the circulation, pro-protein convertase subtilisin-like kexin type 9 (PCSK9) is a secreted protease that binds to and promotes degradation of the LDLR protein. The goal of this case-control study was to investigate the role of soluble LDLR (sLDLR) and PCSK9 in coronary artery disease (CAD) and investigate the relationship between these two indices and CAD.

METHODS

In a sample of 144 Chinese patients recruited between January 2018 and August 2018, 81 cases with mild and severe stenosis characterized by coronary angiograph (CAG) and 63 healthy controls were selected using the propensity score matching (PSM) based on demographics and medical history. sLDLR and PCSK9 concentrations were determined using enzyme-linked immunosorbent assay (ELISA), Immuno-precipitation (IP) and western blotting. Multivariable logistic models were used to assess the associations between the degree of coronary artery stenosis and the biomarkers of interest.

RESULTS

Higher PCSK9 was found to be a significant predictor of coronary artery stenosis when comparing cases who had severe stenosis vs. controls (OR = 1.016, 95%CI: 1.009-1.024), and cases who had mild stenosis vs. controls (OR = 1.009, 95%CI: 1.003-1.015). sLDLR was positively corrected with PCSK9, which confounded the association between CAD and PCSK9. Compared to patients with mild-stenosis, patients with severe-stenosis also showed a higher level of PCSK9 (OR = 1.005, 95%CI: 1.007-1.013).

CONCLUSIONS

These findings suggest that elevated PSCK9 may contribute to the odds of developing CAD, with a higher degree of coronary artery stenosis.

The Association of Proprotein Convertase Subtilisin/Kexin Type 9 to Plasma Low-Density Lipoproteins: An Evaluation of Different Methods

Proprotein convertase subtilisin/kexin type-9 (PCSK9) is key regulator of low-density lipoprotein (LDL) metabolism. A significant proportion of PCSK9 is believed to be associated with LDL in plasma as it circulates, although this finding is still a matter of debate. The purpose of this study was to establish an experimental method to investigate the presence of such an interaction in the bloodstream. We compared a number of well-established methods for lipoprotein (LP) isolation to clarify whether PCSK9 associates differently to circulating lipoproteins, such as KBr gradient ultracentrifugation, physical precipitation of ApoB-LPs, fast protein liquid chromatography (FPLC) and iodixanol gradient ultracentrifugation. Our data show heterogeneity in PCSK9 association to lipoproteins according to the method used. Two methods, iodixanol ultracentrifugation and column chromatography, which did not involve precipitation or high salt concentration, consistently showed an interaction of PCSK9 with a subfraction of LDL that appeared to be more buoyant and have a lower size than average LDL. The percent of PCSK9 association ranged from 2 to 30% and did not appear to correlate to plasma or LDL cholesterol levels. The association of PCSK9 to LDL appeared to be sensitive to high salt concentrations. FPLC and iodixanol gradient ultracentrifugation appeared to be the most suitable methods for the study of this association.

Novel Oral Nano-hepatic targeted anti-PCSK9 in hypercholesterolemia

Proprotein convertase subtilisin/kexin type 9 is a protease enzyme secreted by liver that downregulates hepatic low-density lipoprotein receptor (LDLR) by binding and chaperoning LDLR to lysosomes for degradation, causing hypercholesteremia. The development of anti-PCSK9therapeutics attracted considerable attention for the management of cardiovascular disease risk. However, only subcutaneous injectable PCSK9 monoclonal antibodies have been FDA approved. Oral administration of small-molecule PCSK9 inhibitors has the potential to become a practical therapeutic option if achievable. In the present work, we used nanotechnological approaches to develop the first small oral molecule nano-hepatic targeted anti-PCSK9. Using high-throughput optimization and a series of evaluations, a stable water-dispersible 150-200nm nano-encapsulated drug (named P-4) conjugated with hepatic targeting moiety was synthesized and characterized (named P-21). Pharmacodynamic (PD), pharmacokinetic (PK) and bioavailability studies were conducted using a high fat diet nutritionally induced hypercholesterolemia mouse model to evaluate the efficacy of P-21 as an anti-PCSK9 LDL-cholesterol lowering hepatic targeted nanodrug. The PD results demonstrate that P-21 in a dose-dependent manner is highly effective in lowering LDL-C by 50-90%. PK results show the maximum plasma concentration (C_max) of P-4 was observed after 30min of administration with 31% oral bioavailability and had a sustained longer half-life up to 24h. In vivo safety studies in rats showed no apparent adverse effects, normal chemical biomarkers and normal histopathological findings in all P-21 treated groups at different escalating doses. Compared to the FDA-approved monoclonal antibodies, P-21 offers a more efficient, and practical treatment protocol for targeting uncontrolled hypercholesterolemia in reducing the risk of cardiovascular diseases. The present study introduced a nano-targeted drug delivery approaches for PCSK9/LDLR antagonist.

Monoclonal Antibodies in the Management of Familial Hypercholesterolemia: Focus on PCSK9 and ANGPTL3 Inhibitors

Purpose of Review

Familial hypercholesterolemia (FH) is a monogenic disorder characterized by high plasma levels of low-density lipoprotein cholesterol (LDL-C) since birth and a high risk of premature cardiovascular disease. The genetic defect is carried in only one allele in heterozygous FH (HeFH) or in both in the most severe homozygous FH (HoFH). Current guidelines recommend to reduce substantially LDL-C levels in these high-risk patients, with the need to use association therapy combining agents with different mechanisms of action. As most cases of FH are attributable to mutations in the gene encoding the low-density lipoprotein receptor (LDLR), statins, even in combination with ezetimibe, are less effective in reducing LDL-C plasma levels in FH patients, who require a more intensive approach with additional lipid-lowering agents. Additional targets playing key roles in regulating LDL-C levels are represented by PCSK9 and ANGPTL3.

Recent Findings

Two monoclonal antibodies (mAbs) targeting PCSK9, evolocumab and alirocumab, significantly reduce LDL-C levels in HeFH patients. In patients with HoFH, the efficacy of mAbs to PCSK9 is strictly related to the presence of a residual LDLR activity; thus, patients carrying null mutations do not respond to the therapy with these mAbs, whereas some effects can be appreciated in HoFH bearing defective mutations. Conversely, evinacumab, the mAb targeting ANGPTL3, is highly effective in reducing LDL-C levels even in HoFH patients carrying null LDLR mutations, thanks to its LDLR-independent mechanism of action.

Summary

Monoclonal antibodies inhibiting PCSK9 have shown a robust effect in FH patients presenting a residual LDLR activity, while ANGPTL3 inhibitors appear to be promising even in patients carrying null LDLR mutations.

Primary hypercholesterolemia and development of cardiovascular disorders: Cellular and molecular mechanisms involved in low-grade systemic inflammation and endothelial dysfunction

Primary hypercholesterolemia, a metabolic disorder characterized by elevated circulating levels of cholesterol products, mainly low-density lipoproteins, is associated with arteriosclerosis development. Cardiovascular disease, predominantly myocardial infarction and stroke, remains the main cause of death worldwide, with atherosclerosis considered to be the most common underlying pathology. In addition to elevated plasma levels of low-density lipoproteins, low-grade systemic inflammation and endothelial dysfunction seem to be the main drivers of premature atherosclerosis. Here we review current knowledge related to cellular and molecular mechanisms involved in low-grade systemic inflammation and endothelial dysfunction associated with primary hypercholesterolemia. We also discuss the contribution of different inflammatory mediators, immune players and signaling pathways implicated in leukocyte adhesion to the dysfunctional endothelium, a key feature of atherogenesis development. A better understanding of these processes linked to primary hypercholesterolemia should shed new light on cardiovascular disease development and might guide novel and effective therapeutic strategies to impair its progression.

Diabetic dyslipidaemia

Diabetes mellitus (DM) is an escalating pandemic and an established cardiovascular risk factor. An important aspect of the interaction between DM and atherosclerotic cardiovascular disease (ASCVD) is diabetic dyslipidaemia, an atherogenic dyslipidaemia encompassing quantitative [hypertriglyceridaemia (hyperTG) and decreased high density lipoprotein cholesterol (HDL)] and qualitative [increased small dense low density lipoprotein cholesterol (sdLDL) particles, large very low density lipoprotein cholesterol (VLDL) subfraction (VLDL1) and dysfunctional HDL] modifications in lipoproteins. Much of the pathophysiology linking DM and dyslipidaemia has been elucidated. This paper aims to review the pathophysiology and management of diabetic dyslipidaemia with respect to ASCVD. Briefly, the influence of diabetic kidney disease on lipid profile and lipid changes causing type 2 diabetes mellitus are highlighted. Biomarkers of diabetic dyslipidaemia, including novel markers and clinical trials that have demonstrated that non-lipid and lipid lowering therapies can lower cardiovascular risk in diabetics are discussed. The stands of various international guidelines on lipid management in DM are emphasised. It is important to understand the underlying mechanisms of diabetic dyslipidaemia in order to develop new therapeutic strategies against dyslipidaemia and diabetes. The various international guidelines on lipid management can be used to tailor a holistic approach specific to each patient with diabetic dyslipidaemia.

The relationship between protein convertase subtilisin kexin type-9 levels and extent of coronary artery disease in patients with non-ST-elevation myocardial infarction

BACKGROUND

Cardiovascular disease is one of the leading causes of death worldwide. According to the results of various studies, protein convertase subtilisin kexin type-9 (PCSK9) was determined as a novel risk factor for stable coronary artery disease. Few studies have investigated the relationship between PCSK9 levels and the severity of coronary artery disease in patients with acute coronary syndrome; thus, we herein aimed to investigate this relationship in patients with non-ST-elevation myocardial infarction (NSTEMI) who underwent coronary angiography.

PATIENTS AND METHODS

Herein, 168 patients with NSTEMI were prospectively enrolled, and severity of atherosclerotic lesions was determined using SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery (SYNTAX), Gensini and Jeopardy scores. Plasma PCSK9 levels, lipid parameters and C-reactive protein levels were measured after a 12-h fasting period. The relationship of PCSK9 levels and clinical and laboratory parameters of patients with their SYNTAX, Gensini and Jeopardy scores was investigated.

RESULTS

Pearson correlation analysis showed a strong positive correlation between PCSK9 and the three scores (P < 0.001, r > 0.5 for all). In ROC analysis, a mid-high SYNTAX score of at least 25 was predicted with a sensitivity of 81% and a specificity of 63% when the PCSK9 level was higher than 52.8 ng/ml (area under a curve 0.76, P < 0.001). Multivariate linear regression analysis revealed that PCSK9, low-density lipoprotein cholesterol and creatinine levels were independent predictors of a high SYNTAX score.

CONCLUSION

Taken together, high PCSK9 levels may be a risk factor for adverse events in patients with NSTEMI. Aggressive lipid-lowering therapies may benefit this group of patients.

PCSK9 and atherosclerosis: Looking beyond LDL regulation

Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) is involved in cholesterol homeostasis. After binding to the complex low-density lipoprotein (LDL)-receptor, PCSK9 induces its intracellular degradation, thus reducing serum LDL clearance. In addition to the well-known activity on the hepatic LDL receptor-mediated pathway, PCSK9 has been, however, associated with vascular inflammation in atherogenesis. Indeed, PCSK9 is expressed by various cell types that are involved in atherosclerosis (e.g. endothelial cells, smooth muscle cells and macrophages) and is detected inside human atherosclerotic plaques. We here analyse the biology of PCSK9 and its possible involvement in molecular processes involved in atherosclerosis, beyond the regulation of circulating LDL cholesterol levels.

Hepatic and circulating levels of PCSK9 in morbidly obese patients: Relation with severity of liver steatosis

Non-alcoholic fatty liver disease (NAFLD) is becoming the main cause of liver disease in Western countries, especially in morbidly obese patients (MOPs). The proprotein convertase subtilisin/kexin type 9 (PCSK9) has been recently studied because of its possible involvement in the pathogenesis of NAFLD, but its role, at least in MOPs, is still controversial. The aim of this study was to clarify the correlation between the circulating levels of the PCSK9 protein (cPCSK9) and its hepatic expression with the severity of liver damage in a population of MOPs with NAFLD undergoing bariatric surgery. PCSK9 mRNA was positively correlated with FASN, PPARγ and PPARα mRNAs, while no significant differences were found in PCSK9 mRNA expression in relation to the severity of liver steatosis, lobular inflammation and hepatocellular ballooning. In addition, hepatic PCSK9 protein expression levels were not related to histological parameters of lobular inflammation and hepatocyte ballooning, decreased significantly only in relation to the severity of hepatic steatosis, and were inversely correlated with ALT and AST serum levels. cPCSK9 levels in the whole population were associated with the severity of hepatic steatosis and were positively correlated to total cholesterol levels. In multivariate analysis, cPCSK9 levels were associated with age, total cholesterol and HbA1c. In conclusion, in MOPs our findings support a role for PCSK9 in liver fat accumulation, but not in liver damage progression, and confirm its role in the increase of blood cholesterol, which ultimately may contribute to increased cardiovascular risk in this population.

Evolocumab Effects on Lipoproteins, Measured by High-Performance Liquid Chromatography

AIMS

Profiling of lipoproteins can predict risk of cardiovascular disease; gel permeation high-performance liquid chromatography (HPLC) improves prediction accuracy by providing detailed data for specific lipoprotein subclasses. This study applied HPLC to examine the effects of evolocumab, which effectively treats hyperlipidemia and mixed dyslipidemia, on lipoprotein subclasses, specifically the number and size of lipoprotein particles.

METHODS

This post-hoc analysis used patient blood samples from YUKAWA-2, a phase 3 trial evaluating the efficacy of evolocumab in Japanese adult patients with hyperlipidemia or mixed dyslipidemia and at high risk for cardiovascular disease. We used HPLC to assess observed values and percent change from baseline in cholesterol and triglyceride (TG) concentrations, number of particles in lipoprotein subclasses to week 12, and mean observed values and mean percent change from baseline in variables to weeks 10 and 12. HPLC was also compared with conventional methods in assessing low-density lipoprotein (LDL) cholesterol (LDL-C) values.

RESULTS

Data for all 404 patients were analyzed. Evolocumab significantly decreased cholesterol and TG concentrations, and total particle count, in very low-density lipoprotein (VLDL) and LDL subclasses. Particle size increased slightly in LDL, high-density lipoprotein (HDL), and VLDL, but data varied widely. At very low LDL-C, HPLC measurements were higher than those from conventional methods.

CONCLUSION

This research used HPLC to assess the effects of evolocumab in 20 lipid subclasses. By lowering lipid content and improving the lipid profile, evolocumab may reduce atherogenicity. This reduction is better quantified by HPLC than by conventional methods in the very low LDL-C range.

Cholesterol homeostasis: Researching a dialogue between the brain and peripheral tissues

Cholesterol homeostasis is a highly regulated process in human body because of its several functions underlying the biology of cell membranes, the synthesis of all steroid hormones and bile acids and the need of trafficking lipids destined to cell metabolism. In particular, it has been recognized that peripheral and central nervous system cholesterol metabolism are separated by the blood brain barrier and are regulated independently; indeed, peripherally, it depends on the balance between dietary intake and hepatic synthesis on one hand and its degradation on the other, whereas in central nervous system it is synthetized de novo to ensure brain physiology. In view of this complex metabolism and its relevant functions in mammalian, impaired levels of cholesterol can induce severe cellular dysfunction leading to metabolic, cardiovascular and neurodegenerative diseases. The aim of this review is to clarify the role of cholesterol homeostasis in health and disease highlighting new intriguing aspects of the cross talk between its central and peripheral metabolism.

Ineffective Subtilisin/Kexin Type 9 (PCSK9) Inhibitors Monotherapy in Dyslipidemia with Low-Density Lipoprotein Cholesterol (LDL-C) Receptor Abnormalities: A Report of 2 Cases

Case series

Patients: Male, 44-year-old • Female, 71-year-old

Final Diagnosis: Resistance to PCSK9I overcomed by adding statin

Symptoms: Dyslipidemia

Medication: —

Clinical Procedure: —

Specialty: Cardiology

Progress and prospects of biological approaches targeting PCSK9 for cholesterol-lowering, from molecular mechanism to clinical efficacy

INTRODUCTION

Cardiovascular disorders are one of the leading causes of mortality and morbidity worldwide. Recent advances showed a promising role of proprotein convertase subtilisin/kexin type 9 (PCSK9) as a critical player in regulating plasma LDL levels and lipid metabolism.

AREAS COVERED

This review addresses the molecular functions of PCSK9 with a vision on the clinical progress of utilizing monoclonal antibodies and other biological approaches to block PCSK9 activity. The successful clinical trials with monoclonal antibodies are reviewed. Recent advances in (pre)clinical trials of other biological approaches, such as small interfering RNAs, are also discussed.

EXPERT OPINION

Discovery of PCSK9 and clinical use of its inhibitors to manage lipid metabolism is a step forward in hypolipidaemic therapy. A better understanding of the molecular activity of PCSK9 can help to identify new approaches in the inhibition of PCSK9 expression/activity. Whether if PCSK9 plays a role in other cardiometabolic conditions may provide grounds for further development of therapies.

New Pharmacological Approaches to Target PCSK9

PURPOSE OF REVIEW

Proprotein convertase subtilisin kexin 9 (PCSK9) plays a crucial role in regulating circulating levels of LDL-C as a consequence of its ability to inhibit LDL receptor recycling in the liver. Loss of function variants in the PCSK9 gene result in low LDL-C levels and associate with reduced cardiovascular risk, whereas gain of-function variants associate with hypercholesterolemia and increased risk of early cardiovascular events. Thus, PCSK9 inhibition has been established as an additional approach for the treatment of hypercholesterolemia. The aim of this review is to provide a brief overview of current strategies targeting PCSK9 and discuss clinical results of the emerging approaches.

RECENT FINDINGS

Two monoclonal antibodies targeting circulating PCSK9 (evolocumab and alirocumab) have been approved for the treatment of hypercholesterolemia and cardiovascular disease. Later, a gene silencing approach (inclisiran), which inhibits hepatic PCSK9 synthesis, was shown to be as effective as monoclonal antibodies but with a twice a year injection and is currently under evaluation for approval. Due to the elevated costs of such therapies, several other approaches have been explored, including peptide-based anti PCSK9 vaccination, and small oral PCSK9 inhibitors, which are still in preclinical phase. In the coming years, we will assist to a progressive introduction of novel anti-PCSK9 approaches in the clinical practice for the treatment of patients with hypercholesterolemia as well as patients at high cardiovascular risk.

The history of proprotein convertase subtilisin kexin-9 inhibitors and their role in the treatment of cardiovascular disease

A consensus has formed based on epidemiological studies and clinical trials that intervention to reduce low density lipoprotein cholesterol (LDL-C) will reduce cardiovascular disease (CVD) events. This has progressively reduced the thresholds for intervention and targets for treatment. Whist statins are sufficient for many people in primary prevention, they only partially achieve the newer targets of secondary prevention for established CVD. Increasing use of statins has highlighted that 1–2% cannot tolerate these drugs. Other cholesterol-lowering drugs such as ezetimibe add to the benefits of statins but have limited efficacy. The discovery of activating mutations in proprotein convertase subtilisin kexin-9 (PCSK9) as a cause of familial hypercholesterolaemia while inactivating mutations lower LDL-C led to the idea to develop PCSK9 inhibitors as drugs. This article reviews the history of lipid-lowering therapies, the discovery of PCSK9 and the development of PCSK9 inhibitors. It reviews the key trials of the current antibody-based drugs and how these have influenced new guidelines. It also reviews the controversy caused by their cost and the increasing application of health economics to determine the optimum strategy for implementation of novel therapeutic pathways and surveys other options for targeting PCSK9 as well as other LDL-C lowering compounds in late development.

Novel strategies to target proprotein convertase subtilisin kexin 9: beyond monoclonal antibodies

Since the discovery of the role of proprotein convertase subtilisin kexin 9 (PCSK9) in the regulation of low-density lipoprotein cholesterol (LDL-C) in 2003, a paradigm shift in the treatment of hypercholesterolaemia has occurred. The PCSK9 secreted into the circulation is a major downregulator of the low-density lipoprotein receptor (LDLR) protein, as it chaperones it to endosomes/lysosomes for degradation. Humans with loss-of-function of PCSK9 exhibit exceedingly low levels of LDL-C and are protected from atherosclerosis. As a consequence, innovative strategies to modulate the levels of PCSK9 have been developed. Since 2015 inhibitory monoclonal antibodies (evolocumab and alirocumab) are commercially available. When subcutaneously injected every 2-4 weeks, they trigger a ∼60% LDL-C lowering and a 15% reduction in the risk of cardiovascular events. Another promising approach consists of a liver-targetable specific PCSK9 siRNA which results in ∼50-60% LDL-C lowering that lasts up to 6 months (Phases II-III clinical trials). Other strategies under consideration include: (i) antibodies targeting the C-terminal domain of PCSK9, thereby inhibiting the trafficking of PCSK9-LDLR to lysosomes; (ii) small molecules that either prevent PCSK9 binding to the LDLR, its trafficking to lysosomes or its secretion from cells; (iii) complete silencing of PCSK9 by CRISPR-Cas9 strategies; (iv) PCSK9 vaccines that inhibit the activity of circulating PCSK9. Time will tell whether other strategies can be as potent and safe as monoclonal antibodies to lower LDL-C levels.

Alirocumab Administration Experience to Achieve Low Density Lipoprotein Cholesterol Target Levels in Secondary Prevention of Cardiovascular Disease

Aim. To study the effects of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor, alirocumab, on lipid levels in patients who receive secondary prevention of cardiovascular diseases (CVD) and require enhanced lipid-lowering therapy.

Material and methods. The study included 49 patients (aged of 61.53±1.14 years; 31 [63.3%] men) receiving alirocumab who did not reach the target low density lipoprotein cholesterol (LDL-C) concentrations despite the ongoing optimal lipid-lowering therapy. In all patients, the initial level of lipids was evaluated, as well as their parameters after subsequent alirocumab injections.

Results. LDL-C serum level significantly decreased after the first injection compared to the initial level from 2.92±0.22 to 1.65±0.19 mmol/L (p<0.001; Δ45.31±3.61%) and down to 1.74±0.17 mmol/L for the entire study period (p<0.001; Δ41.52±2.69%). The change in LDL-C level between injections did not show statistically significant differences (p=0.141). A direct strong statistically significant correlation between the LDL-C level after the first injection and its average values for the entire observation period was found (r=0.958, p<0.001).

Conclusion. The results of the study indicate that the PCSK9 inhibitor, alirocumab, in patients who need secondary prevention of CVD shows a significant additional decrease in the concentration of LDL-C after the first injection. At the same time, approximately half of the patients were able to achieve the recommended levels of LDL-C. The persistence of the achieved low LDL-C levels over time demonstrated that the average concentration of LDL-C during the observation corresponded to the values after the first injection. This finding shows that there is no need for constant monitoring of lipid metabolism parameters when prescribing such therapy.

Rare Diseases Related with Lipoprotein Metabolism

Rare diseases are gathering increasing attention in last few years, not only for its effects on innovation scientific research, but also for its propounding influence on common diseases. One of the most famous milestones made by Michael Brown and Joseph Goldstein in metabolism field is the discovery of the defective gene in familial hypercholesterolemia, a rare human genetic disease manifested with extreme high level of serum cholesterol (Goldstein JL, Brown MS, Proc Natl Acad Sci USA 70:2804-2808, 1973; Brown MS, Dana SE, Goldstein JL, J Biol Chem 249:789-796, 1974). Follow-up work including decoding the gene function, mapping-related pathways, and screening therapeutic targets are all based on the primary finding (Goldstein JL, Brown MS Arterioscler Thromb Vasc Biol 29:431-438, 2009). A series of succession win the two brilliant scientists the 1985 Nobel Prize, and bring about statins widely used for lipid management and decreasing cardiovascular disease risks. Translating the clinical extreme phenotypes into laboratory bench work has turned out to be the first important step in the paradigm conducting translational and precise medical research. Here we review the main categories of rare disorders related with lipoprotein metabolism, aiming to strengthen the notion that human rare inheritable genetic diseases would be the window to know ourselves better, to treat someone more efficiently, and to lead a healthy life longer. Few rare diseases related with lipoprotein metabolism were clustered into six sections based on changes in lipid profile, namely, hyper- or hypocholesterolemia, hypo- or hyperalphalipoproteinemia, abetalipoproteinemia, hypobetalipoproteinemia, and sphingolipid metabolism diseases. Each section consists of a brief introduction, followed by a summary of well-known disease-causing genes in one table, and supplemented with one or two diseases as example for detailed description. Here we aimed to raise more attention on rare lipoprotein metabolism diseases, calling for more work from basic research and clinical trials.

PCSK9 Inhibition and Atherosclerosis: Current Therapeutic Option and Prospection

Low-density lipoprotein cholesterol (LDL-C) is a pivotal factor in atherosclerotic cardiovascular disease (ASCVD), the leading cause of worldwide mortality. The limitations of statin therapy require alternative treatment strategies to achieve target LDL-C level. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays an important role in LDLR recycling, consequently regulating plasma cholesterol levels. Monoclonal antibodies targeting PCSK9 increased expression of LDLRs at the cell surface and therefore decreased circulating LDL-C. PCSK9 inhibitors have shown great efficacy in reducing plasma LDL-C levels, which needs to inject once or twice monthly. Though SPIRE sponsors concern the immunogenicity and terminate trials early, FOURIER and ODYSSER OUTCOME trials improved the efficacy of PCSK9 inhibitors in LDL-C reduction. Inclisiran actually is a small interfering RNA (siRNA) developed to inhibit PCSK9 messenger RNA, leading to reduced concentrations of the PCSK9 protein and thereby lower concentrations of LDL-C. Inclisiran is a latest alternative treatment to cholesterol-lowering therapeutics. Twice injections of inclisiran durably reduced LDL-C levels over 1 year. siRNA therapeutics provided a simple, novel, and less frequent approach to LDL-C reduction in phase I and II trials, which may be used either as in combination with statin therapeutics or a stand-alone therapy in the future.

[The problem of safety of lipid-lowering therapy]

This study focused on analysis of current publications evaluating safety of lipid-lowering therapy. Search for literature was performed on websites of cardiological societies and online databases, including PubMed, EMBASE, and eLibrary by the following key words: statins, statin intolerance, lipid-lowering therapy, statin safety, and statin аdverse effects. The focus is on statins, in view of the fact that they are the most commonly prescribed, highly effective and safe drugs for primary and secondary cardiovascular prophylaxis. This review consistently summarized information about myopathies, hepatic and renal dysfunction, potentiation of DM, and other possible adverse effects of lipid-lowering therapy. The author concluded that despite the high safety of statins acknowledged by all international cardiological societies, practicing doctors still continue unreasonably cancel statins, exposing the patient under even greater danger. Information about the corresponding author.

Evolocumab, a proprotein convertase subtilisin/kexin type 9 inhibitor, promotes angiogenesis in vitro

The proprotein convertases family is involved in several physiological processes such as cell growth, migration, and angiogenesis, and also in different pathological conditions. Evolocumab, an inhibitor of proprotein convertase subtilisin/kexin type 9 (PCSK9), has recently been approved for treatment of hypercholesterolemia. This study aimed to investigate the effect of evolocumab on angiogenesis in human umbilical vein endothelial cells (HUVECs). Cell proliferation and migration were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Transwell methods. In vitro angiogenesis was assessed by tube formation assay. Vascular endothelial growth factor (VEGF) secretion by HUVECs was also determined using an enzyme-linked immunosorbent assay kit. Evolocumab significantly increased HUVECs viability at 100 μg/mL. Significant enhancement in cell migration, and mean tubules length and size was observed at the concentrations of 10 and 100 μg/mL and also in mean number of junctions at the concentration of 100 μg/mL. Administration of evolocumab at the concentration of 10 μg/mL increased VEGF release into supernatants of HUVECs. Findings of this investigation provided in vitro evidence for pro-angiogenic activity of evolocumab through promoting cell proliferation, migration, tubulogenesis, and VEGF secretion in HUVECs.

PCSK9 inhibition 2018: riding a new wave of coronary prevention

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a hepatic enzyme that regulates the low-density lipoprotein cholesterol (LDL-c) receptor and thus circulating LDL-c levels. With overwhelming evidence now supporting the reduction in LDL-c to lower the risk of cardiovascular disease, PCSK9 inhibitors represent an important therapeutic target, particularly in high-risk populations. Here, we summarise and update the science of PCSK9, including its discovery and the development of various inhibitors, including the now approved monoclonal antibodies. In addition, we summarise the clinical applications of PCSK9 inhibitors in a range of patient populations, as well as the major randomised controlled trials investigating their use in coronary prevention.

Relationship between Plasma Proprotein Convertase Subtilisin/Kexin Type 9 and Estimated Glomerular Filtration Rate in the General Chinese Population

BACKGROUND

Elevated levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) have been reported to be related to dyslipidemia, including patients with kidney dysfunction. However, its association with estimated glomerular filtration rate (eGFR) in individuals with normal serum creatinine (SCr) has not been determined.

METHODS

A total of 2,089 subjects with normal SCr and without lipid-lowering treatment were consecutively enrolled in this study. Plasma PCSK9 levels were measured by ELISA kit and eGFR was evaluated by the Chronic Kidney Disease Epidemiology Collaboration equation. Subjects were divided into a normal eGFR group (n = 1,205, ≥90 mL/min/1.73 m2) and a decreased eGFR group (n = 884, < 90 mL/min/1.73 m2). Baseline characteristics and laboratory findings were compared between the two groups. Spearman's correlation and linear regression were performed to determine the association between PCSK9 and eGFR.

RESULTS

No significant difference in PCSK9 levels was found between the normal eGFR group and the decreased eGFR group (236.84 ± 67.87 vs. 239.98 ± 68.72 ng/mL, p = 0.303). In Spearman's correlation and multivariable linear regression analysis, no association of PCSK9 levels with eGFR was detected in the total cohort (r = -0.039, p = 0.079; adjusted β = -0.013, p = 0.630). This result remained the same in the subgroups of normal eGFR (r = -0.038, p = 0.190; adjusted β = -0.031, p = 0.367) and decreased eGFR (r = -0.054, p = 0.109; adjusted β = -0.034, p = 0.319).

CONCLUSION

In this single-center study with moderate sample size, the data showed no relationship of PCSK9 levels with normal or decreased eGFR in untreated patients with normal SCr, suggesting that further studies may be needed to understand the relationship between PCSK9 and lipid disorder in different stage of kidney dysfunction.

Molecular aspects of hypercholesterolemia treatment: current perspectives and hopes

Hypercholesterolemia is a pathological condition which has been reported in 39% of the worlds' adult population. We aimed to review molecular aspects of current and novel therapeutic approaches based on low-density lipoprotein cholesterol lowering strategies. Pathogenic mutations in the LDLR, ApoB, PCSK9 and LDLRAP genes cause deficient clearance of circulating low-density lipoprotein cholesterol particles via hepatic LDL receptor. This leads to increased plasma LDL cholesterol levels from birth, which can cause LDL depositions in the arterial walls. Ultimately, it progresses to atherosclerosis and an increased risk of premature cardiovascular diseases. Currently, statins, Ezetimibe, Bile acid sequestrants and PCSK9 inhibitors are the main therapeutic agents for the treatment of hypercholesterolemia. Moreover, novel RNA-based therapy had a strong impact on therapeutic strategies in recent decades. Additional development in understanding of the molecular basis of hypercholesterolemia will provide opportunities for the development of targeted therapy in the near future. Key Messages The most common genes involved in hypercholesterolemia are LDLR, PCSK9 and ApoB. Pharmacogenetic effects are typically constrained to pathways closely related to the pharmacodynamics and pharmacokinetics. Change in lifestyle and diet along with treatment of the underlying disease and drug therapy are the current therapeutic strategies.

Effective low-density lipoprotein-lowering therapy: Implementation in clinical practice

Although age-adjusted mortality of coronary heart disease has been successfully reduced over recent years, coronary heart disease still represents a leading cause of death and morbidity, in particular in patients at very high cardiovascular risk. Dyslipidaemia plays a major and causal role in the development and clinical progression of coronary heart disease. At present, low-density lipoprotein cholesterol represents the primary target of lipid-directed therapies for the prevention of cardiovascular disease and events. The new European guidelines recommend intensive statin therapy and the possible addition of ezetimibe to reduce low-density lipoprotein cholesterol to a goal of less than 1.8 mmol/L (<70 mg/dL) or by at least 50% if the baseline low-density lipoprotein cholesterol is between 1.8 and 3.5 mmol/L (70-135 mg/dL) in patients at very high cardiovascular risk. Also, the new European guidelines now mention the potential use of proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors in very high-risk patients with persistently high levels of low-density lipoprotein cholesterol despite maximally tolerated statin treatment in combination with ezetimibe or in patients with statin intolerance. A recent European consensus document discusses the practical clinical use of PCSK9 inhibitors and provides more detailed recommendations. However, despite the overwhelming scientific evidence of the beneficial effects of lipid-lowering therapies, a large proportion of patients at very high cardiovascular risk are not treated according to the current European guideline recommendations. Reinforcing lipid-lowering therapies provides an excellent chance effectively to reduce morbidity and mortality from coronary heart disease.