Beyond LDL: What Role for PCSK9 in Triglyceride-Rich Lipoprotein Metabolism?

Olezarsen, a liver-directed APOC3 ASO therapy for hypertriglyceridemia

INTRODUCTION

Apolipoprotein (apo)C-III, a key regulator of plasma triglyceride (TG) levels, is a prime candidate for the treatment of hypertriglyceridemia (HTG), prevention of acute pancreatitis, and reduction of future atherosclerotic cardiovascular disease (ASCVD) events.

AREAS COVERED

We discuss the role of apoC-III as a therapeutic target for HTG, describe the pharmacodynamics, pharmacokinetics, and metabolism of olezarsen, as well as report on the findings of recent clinical trials with this liver-directed APOC3 antisense oligonucleotide (ASO).

EXPERT OPINION

Olezarsen, a GalNac-conjugated ASO targeting apoC-III, can reduce TG levels by ~ 50% in patients with extreme HTG due to familial chylomicronemia syndrome, as well as in patients with moderate HTG. Attention is now focused on whether olezarsen reduces ASCVD risk in patients with moderate and severe HTG. While olezarsen does cause elevations in liver enzymes, these changes are not clinically meaningful, and are not associated with thrombocytopenia, an issue with its predecessor, volanesorsen. The need for 4-weekly administration puts olezarsen at a disadvantage to competing injectables. Results from the CORE, CORE2, and ESSENCE phase III clinical trials in patients with severe HTG, expected in the second half of 2025, will help determine the requirement for a larger cardiovascular outcomes trial.

A novel small-molecule PCSK9 inhibitor E28362 ameliorates hyperlipidemia and atherosclerosis

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the epidermal growth factor precursor homologous domain A (EGF-A) of low-density lipoprotein receptor (LDLR) in the liver and triggers the degradation of LDLR via the lysosomal pathway, consequently leading to an elevation in plasma LDL-C levels. Inhibiting PCSK9 prolongs the lifespan of LDLR and maintains cholesterol homeostasis in the body. Thus, PCSK9 is an innovative pharmacological target for treating hypercholesterolemia and atherosclerosis. In this study, we discovered that E28362 was a novel small-molecule PCSK9 inhibitor by conducting a virtual screening of a library containing 40,000 compounds. E28362 (5, 10, 20 μM) dose-dependently increased the protein levels of LDLR in both total protein and the membrane fraction in both HepG2 and AML12 cells, and enhanced the uptake of DiI-LDL in AML12 cells. MTT assay showed that E28362 up to 80 μM had no obvious toxicity in HepG2, AML12, and HEK293a cells. The effects of E28362 on hyperlipidemia and atherosclerosis were evaluated in three different animal models. In high-fat diet-fed golden hamsters, administration of E28362 (6.7, 20, 60 mg·kg-1·d-1, i.g.) for 4 weeks significantly reduced plasma total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C) and PCSK9 levels, and reduced liver TC and TG contents. In Western diet-fed ApoE-/- mice (20, 60 mg·kg-1·d-1, i.g.) and human PCSK9 D374Y overexpression mice (60 mg·kg-1·d-1, i.g.), administration of E28362 for 12 weeks significantly decreased plasma LDL-C levels and the area of atherosclerotic lesions in en face aortas and aortic roots. Moreover, E28362 significantly increased the protein expression level of LDLR in the liver. We revealed that E28362 selectively bound to PCSK9 in HepG2 and AML12 cells, blocked the interaction between LDLR and PCSK9, and induced the degradation of PCSK9 through the ubiquitin-proteasome pathway, which finally resulted in increased LDLR protein levels. In conclusion, E28362 can block the interaction between PCSK9 and LDLR, induce the degradation of PCSK9, increase LDLR protein levels, and alleviate hyperlipidemia and atherosclerosis in three distinct animal models, suggesting that E28362 is a promising lead compound for the treatment of hyperlipidemia and atherosclerosis.

Efficacy of Alirocumab, Evolocumab, and Inclisiran in Patients with Hypercholesterolemia at Increased Cardiovascular Risk

Background and Objectives: Lowering low-density lipoprotein (LDL-C) levels is critical for preventing atherosclerotic cardiovascular disease, yet some patients fail to reach the LDL-C targets despite available intensive lipid-lowering therapies. This study assessed the effectiveness and safety profile of alirocumab, evolocumab, and inclisiran in lipid reduction. Materials and Methods: A cohort of 51 patients (median (Q1-Q3) age: 49.0 (39.5-57.5) years) was analyzed. Eligibility included an LDL-C level > 2.5 mmol/L while on the maximum tolerated dose of statin and ezetimibe, a diagnosis of familial hypercholesterolemia, or a very high risk of cardiovascular diseases following myocardial infarction within 12 months prior to the study. Follow-ups and lab assessments were conducted at baseline (51 patients), 3 months (51 patients), and 15 months (26 patients) after the treatment initiation. Results: Median initial LDL-C levels 4.1 (2.9-5.0) mmol/L, decreasing significantly to 1.1 (0.9-1.6) mmol/L at 3 months and 1.0 (0.7-1.8) mmol/L at 15 months (p < 0.001). Total cholesterol also reduced significantly compared to baseline at both intervals (p < 0.001). No substantial differences in LDL-C or total cholesterol levels were observed between 3- and 15-month observations (p > 0.05). No statistically significant differences were noted in cholesterol reduction among the alirocumab, evolocumab, and inclisiran groups at 3 months. The safety profile was favorable, with no reported adverse cardiovascular events or significant changes in alanine transaminase, creatinine, or creatine kinase levels. Conclusions: Alirocumab, evolocumab, and inclisiran notably decreased LDL-C and total cholesterol levels without significant adverse effects, underscoring their potential as effective treatments in patients who do not achieve lipid targets with conventional therapies.

Role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in diabetic complications

Cardiovascular disease (CVD) complications have remained a major cause of death among patients with diabetes. Hence, there is a need for effective therapeutics against diabetes-induced CVD complications. Since its discovery, proprotein convertase subtilisin/kexin type 9 (PCSK9) has been reported to be involved in the pathology of various CVDs, with studies showing a positive association between plasma levels of PCSK9, hyperglycemia, and dyslipidemia. PCSK9 regulates lipid homeostasis by interacting with low-density lipoprotein receptors (LDLRs) present in hepatocytes and subsequently induces LDLR degradation via receptor-mediated endocytosis, thereby reducing LDL uptake from circulation. In addition, PCSK9 also induces pro-inflammatory cytokine expression and apoptotic cell death in diabetic-CVD. Furthermore, therapies designed to inhibit PCSK9 effectively reduces diabetic dyslipidemia with clinical studies reporting reduced cardiovascular events in patients with diabetes and no significant adverse effect on glycemic controls. In this review, we discuss the role of PCSK9 in the pathogenesis of diabetes-induced CVD and the potential mechanisms by which PCSK9 inhibition reduces cardiovascular events in diabetic patients.

A bifunctional anti-PCSK9 scFv/Exendin-4 fusion protein exhibits enhanced lipid-lowering effects via targeting multiple signaling pathways in HFD-fed mice

Fusion protein which encompasses more than one functional component, has become one of the most important representatives of macromolecular drugs for disease treatment since that monotherapy itself might not be effective enough to eradicate the disease. In this study, we sought to construct a bifunctional antibody fusion protein by fusing anti-PCSK9 scFv with Exendin-4 for simultaneously lowering both LDL-C and TG. Firstly, three Ex4-anti-PCSK9 scFv fusion proteins were constructed by genetically connecting the C-terminal of Exendin-4 to the N-terminal of anti-PCSK9 scFv through various flexible linker peptides (G4S)n (n = 2, 3, 4). After soluble expression in E. coli, the most potent Ex4-(G4S)4-anti-PCSK9 scFv fusion protein was selected based on in vitro activity assays. Then, we investigated the in vivo therapeutic effects of Ex4-(G4S)4-anti-PCSK9 scFv on the serum lipid profile and bodyweight changes as well as underlying molecular mechanism in HFD-fed C57BL/6 mice. The data showed that Ex4-(G4S)4-anti-PCSK9 scFv exhibits enhanced effects of lowering both LDL-C and TG in serum, reducing food intake and body weight via blocking PCSK9/LDLR, activating AMPK/SREBP-1 pathways, and up-regulating sirt6. Conclusively, Ex4-(G4S)4-anti-PCSK9 has the potential to serve as a promising therapeutic agent for effectively treating dyslipidemia with high levels of both LDL-C and TG.

The association between circulatory, local pancreatic PCSK9 and type 2 diabetes mellitus: The effects of antidiabetic drugs on PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent modulator of cholesterol metabolism and plays a crucial role in the normal functioning of pancreatic islets and the progression of diabetes. Islet autocrine PCSK9 deficiency can lead to the enrichment of low-density lipoprotein (LDL) receptor (LDLR) and excessive LDL cholesterol (LDL-C) uptake, subsequently impairing the insulin secretion in β-cells. Circulatory PCSK9 levels are primarily attributed to hepatocyte secretion. Notably, anti-PCSK9 strategies proposed for individuals with hypercholesterolemia chiefly target liver-derived PCSK9; however, these anti-PCSK9 strategies have been associated with the risk of new-onset diabetes mellitus (NODM). In the current review, we highlight a new direction in PCSK9 inhibition therapy strategies: screening candidates for anti-PCSK9 from the drugs used in type 2 diabetes mellitus (T2DM) treatment. We explored the association between circulating, local pancreatic PCSK9 and T2DM, as well as the relationship between PCSK9 monoclonal antibodies and NODM. We discussed the emergence of artificial and natural drugs in recent years, exhibiting dual benefits of antidiabetic activity and PCSK9 reduction, confirming that the diverse effects of these drugs may potentially impact the progression of diabetes and associated disorders, thereby introducing novel avenues and methodologies to enhance disease prognosis.

Cardiac Alarmins as Residual Risk Markers of Atherosclerosis under Hypolipidemic Therapy

Increased levels of low-density lipoproteins are the main risk factor in the initiation and progression of atherosclerosis. Although statin treatment can effectively lower these levels, there is still a residual risk of cardiovascular events. We hypothesize that a specific panel of stress-sensing molecules (alarmins) could indicate the persistence of silent atherosclerosis residual risk. New Zealand White rabbits were divided into: control group (C), a group that received a high-fat diet for twelve weeks (Au), and a treated hyperlipidemic group with a lipid diet for eight weeks followed by a standard diet and hypolipidemic treatment (atorvastatin and PCSK9 siRNA-inhibitor) for four weeks (Asi). Mass spectrometry experiments of left ventricle lysates were complemented by immunologic and genomic studies to corroborate the data. The hyperlipidemic diet determined a general alarmin up-regulation tendency over the C group. A significant spectral abundance increase was measured for specific heat shock proteins, S100 family members, HMGB1, and Annexin A1. The hypolipidemic treatment demonstrated a reversed regulation trend with non-significant spectral alteration over the C group for some of the identified alarmins. Our study highlights the discriminating potential of alarmins in hyperlipidemia or following hypolipidemic treatment. Data are available via ProteomeXchange with identifier PXD035692.

Effect of PCSK9 inhibition with evolocumab on lipoprotein subfractions in familial dysbetalipoproteinemia (type III hyperlipidemia)

BACKGROUND AND AIMS

Familial dysbetalipoproteinemia (FDBL) is a rare inborn lipid disorder characterized by the formation of abnormal triglyceride- and cholesterol-rich lipoproteins (remnant particles). Patients with FDBL have a high risk for atherosclerotic disease. The effect of PCSK9 inhibition on lipoproteins and its subfractions has not been evaluated in FDBL.

METHODS

Three patients (65±7 years, 23±3 kg/m2, 2 females) with FDBL (diagnosed by isoelectrofocusing) and atherosclerosis (coronary and/or cerebro-vascular and/or peripheral arterial disease) resistant or intolerant to statin and fibrate therapy received evolocumab (140mg every 14 days). In addition to a fasting lipid profile (preparative ultracentrifugation), apoB and cholesterol concentrations were determined in 15 lipoprotein-subfractions (density gradient ultracentrifugation; d 1.006-1.21g/ml) before and after 12 weeks of evolocumab treatment. Patients with LDL-hypercholesterolemia (n = 8, 56±8 years, 31±7 kg/m2) and mixed hyperlipidemia (n = 5, 68±12 years, 30±1 kg/m2) also receiving evolocumab for 12 weeks were used for comparison.

RESULTS

All patients tolerated PCSK9 inhibition well. PCSK9 inhibitors reduced cholesterol (29-37%), non-HDL-cholesterol (36-50%) and apoB (40-52%) in all patient groups including FDBL. In FDBL, PCSK9 inhibition reduced VLDL-cholesterol and the concentration of apoB containing lipoproteins throughout the whole density spectrum (VLDL, IDL, remnants, LDL). Lipoprotein(a) was decreased in all patient groups to a similar extent.

CONCLUSIONS

This indicates that the dominant fraction of apoB-containing lipoproteins is reduced with PCSK9 inhibition, i.e. LDL in hypercholesterolemia and mixed hyperlipidemia, and cholesterol-rich VLDL, remnants and LDL in FDBL. PCSK9 inhibition may be a treatment option in patients with FDBL resistant or intolerant to statin and/or fibrate therapy.

PCSK9 inhibitors revisited: Effectiveness and safety of PCSK9 inhibitors in a real-life Spanish cohort

INTRODUCTION

Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) have emerged as a therapeutic option for patients with hypercholesterolemia who do not attain low-density lipoprotein cholesterol (LDL-C) goals and/or are intolerant to other lipid-lowering drugs. Our aim was to analyze the effectiveness and safety of PCSK9i in routine clinical practice and factors related to poor outcomes.

MATERIALS AND METHODS

We conducted an ambispective study in 115 patients who recieved alirocumab or evolocumab, in a tertiary level hospital. From February 2017 to April 2020, patients were recruited and followed up for a median of 20.4 months. The main outcomes were relative reduction in LDL-C, percentage of patients achieving the therapeutic goals established by 2016 ESC/EAS guidelines, incidence of major cardiovascular events (MACEs) and drug-related adverse events (ADRs).

RESULTS

The median LDL-C achieved was 57.0 mg/dL (relative reduction of 59.9% from baseline, p< 0.001). After adjusting for confounders, smaller LDL-C reductions were related to female sex, absence of concomitant lipid-lowering therapy and treatment with alirocumab. Overall, 84.6% of the patients achieved the therapeutic goals. During follow-up, 7 MACEs were detected. ADRs, generally considered mild, affected 38.1% of the participants (mainly mialgias and arthralgias) and triggered discontinuations in 8.7% of cases.

CONCLUSIONS

PCSK9i are effective and safe, although certain factors may influence their effectiveness. Interestingly, our results suggest that alirocumab and evolocumab may not be therapeutic equivalents, as initially suggested.

Low baseline plasma PCSK9 level is associated with good clinical outcomes of immune checkpoint inhibitors in advanced non‐small cell lung cancer

Background

Methods

Results

Conclusions

Inclisiran: a small interfering RNA strategy targeting PCSK9 to treat hypercholesterolemia

INTRODUCTION

Inclisiran is a novel posttranscriptional gene silencing therapy that inhibits proprotein convertase subtilisin/kexin type 9 (PCSK9) synthesis by RNA interference and has a potent, dose-dependent, durable effect in lowering LDL-C, and therefore is an effective drug to treat dyslipidemia, reducing the risk for acute cardiovascular (CV) events. It is safe and well-tolerated.

AREAS COVERED

This paper aims to review the mechanism of action of inclisiran while evaluating its efficacy and safety in the treatment of dyslipidemia from data of the clinical trials in the ORION program.

EXPERT OPINION

Data from the clinical trials in the ORION program demonstrated efficacy and safety of inclisiran in patients with dyslipidemia. Adverse events were similar in the inclisiran and placebo groups in the clinical trials, although injection-site reactions were more frequent with inclisiran than with placebo. Although the combination of efficacy and safety makes inclisiran a good option for the treatment of dyslipidemia compared to other PCSK9 targeting therapeutic strategies, however, further studies should exclude the possibility that inclisiran, through lower-affinity interactions, may influence other mRNAs in the physiological milieu.

PCSK9 Gene Participates in the Development of Primary Dyslipidemias

Dyslipidemias are a group of diseases, which are characterized by abnormal blood concentrations of cholesterol, triglycerides and/or low-density lipoprotein-cholesterol (LDL-c). Dyslipidemia is a determinant condition for the progress of an atherosclerotic plaque formation. The resulting atherogenicity is due to at least two mechanisms: first, to the accumulation in the plasma of lipid particles that have the capacity to alter the function of the endothelium and deposit at the atheromatous plaque, and second, at an insufficient concentration of multifactorial type of high density lipoprotein-cholesterol (HDL-c), whose function is to protect against the development of atherosclerosis. Its highest prevalence is encountered among individuals with diabetes, hypertension or overweight. Hyperlipidemia is one of the main predisposing factors for the development of cardiovascular disease. Hyperlipidemia can be the result of a genetic condition, the secondary expression of a primary process or the consequence of exogenous factors (food, cultural, socio-economic, etc.), all of which lead to the elevation of plasma lipid levels. The objective of this study was to carry out an analysis of the genes involved in the development of dyslipidemias that lead to cardiovascular disease with special emphasis on the proprotein convertase subtilin/kexin type 9 (PCSK9) gene. The PCSK9 gene participates in the development of primary dyslipidemias, mainly familial hypercholesterolemia, currently the pharmacological treatment of choice to reduce LDL-c are statins, however, it has been observed that these have been insufficient to eliminate cardiovascular risk, especially in subjects with primary forms of hypercholesterolemia related to genetic mutations, or statin intolerance.

Proprotein Convertase Subtilisin/Kexin Type 9: A View beyond the Canonical Cholesterol-Lowering Impact

Proprotein convertase subtilisin/kexin type 9 (PCSK9), mainly synthetized and released by the liver, represents one of the key regulators of low-density lipoprotein cholesterol. Although genetic and interventional studies have demonstrated that lowering PCSK9 levels corresponds to a cardiovascular benefit, identification of non-cholesterol-related processes has emerged since its discovery. Besides liver, PCSK9 is also expressed in many tissues (eg, intestine, endocrine pancreas, and brain). The aim of the present review is to describe and discuss PCSK9 pathophysiology and possible non-lipid-lowering effects whether already extensively characterized (eg, inflammatory burden of atherosclerosis, triglyceride-rich lipoprotein metabolism, and platelet activation), or to be unraveled (eg, in adipose tissue). The identification of novel transcriptional factors in the promoter region of human PCSK9 (eg, ChREBP) characterizes new mechanisms explaining how controlling intrahepatic glucose may be a therapeutic strategy to reduce cardiovascular risk in type 2 diabetes. Finally, the evidence describing PCSK9 as involved in cell proliferation and apoptosis raises the possibility of this protein being involved in cancer risk.

Real-world data on metabolic effects of PCSK9 inhibitors in a tertiary care center in patients with and without diabetes mellitus

Background

The lipid-lowering and positive cardiovascular effect of proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors was shown in several studies, hence, they are more widely used in the lipid-lowering management of individuals with high cardiovascular risk. As real-world data are still scarce, specifically in patients with type 2 diabetes (T2D), the aim of this retrospective analysis was to investigate the efficacy of PCSK9 inhibitors in lowering low-density lipoprotein cholesterol (LDL-C) in an outpatient clinic of a tertiary care center in routine care.

Methods

A retrospective analysis of data extracted from the electronic patient record was performed. Patients who were routinely prescribed with PCSK9 inhibitor therapy (alirocumab or evolocumab) during the years 2016 and 2019 were included in the analysis. Characteristics of the patient population, the effects on LDL-C and HbA1c levels as well as subsequent cardiovascular events were assessed over an observation period of 18 months.

Results

We identified 237 patients treated with PCSK9 inhibitors between January 2016 and September 2019. Almost all patients (97.5%) received PCSK9 inhibitors for secondary prevention. 26.2% of the population had a concomitant diabetes diagnosis. Intolerance to statins (83.1%), ezetimibe (44.7%) or both agents (42.6%) was reported frequently. Three months after initiation of PCSK9 inhibitor therapy, 61.2% of the patients achieved LDL-C levels < 70 mg/dl, and 44.1% LDL-C levels < 55 mg/dl. The median LDL-C was lowered from 141 mg/dl at baseline, to 60 mg/dl after 3 months and 66 mg/dl after 12 months indicating a reduction of LDL-C as follows: 57.5% after 3 months and 53.6% after 12 months. After 3 months of observation, target achievement of LDL-C was higher in patients with T2D compared to non-diabetes patients; < 55 mg/dl: 51% vs. 41.5%; < 70 mg/dl 69.4 vs. 58.5%. After 12 months even more pronounced target LDL achievement in T2D was demonstrated < 55 mg/dl: 58.8% vs. 30.1%; < 70 mg/dl 70.6 vs. 49.6%. Patients with insufficiently controlled T2D (HbA1c > 54 mmol/mol) had a higher reduction in LDL-C but still were more likely to subsequent cardiovascular events.

Conclusions

Significant reductions in LDL-C and a high percentage of patients achieving recommended treatment targets were observed. The percentage of patients with T2D meeting recommended LDL-C targets was higher than in those without T2D. Still some patients did not achieve LDL-C levels as recommended in current guidelines. Special attention to the characteristics of these patients is required in the future to enable achievement of treatment goals and avoid adverse cardiovascular outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01283-w.

PCSK9 in Myocardial Infarction and Cardioprotection: Importance of Lipid Metabolism and Inflammation

Extensive evidence from epidemiologic, genetic, and clinical intervention studies has indisputably shown that elevated low-density lipoprotein cholesterol (LDL-C) concentrations play a central role in the pathophysiology of atherosclerotic cardiovascular disease. Apart from LDL-C, also triglycerides independently modulate cardiovascular risk. Reduction of proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a therapeutic target for reducing plasma LDL-C, but it is also associated with a reduction in triglyceride levels potentially through modulation of the expression of free fatty acid transporters. Preclinical data indicate that PCSK9 is up-regulated in the ischaemic heart and decreasing PCSK9 expression impacts on infarct size, post infarct inflammation and remodeling as well as cardiac dysfunction following ischaemia/reperfusion. Clinical data support that notion in that PCSK9 inhibition is associated with reductions in the incidence of myocardial infarction, stroke, and coronary revascularization and an improvement of endothelial function in subjects with increased cardiovascular risk. The aim of the current review is to summarize the current knowledge on the importance of free fatty acid metabolism on myocardial ischaemia/reperfusion injury and to provide an update on recent evidence on the role of hyperlipidemia and PCSK9 in myocardial infarction and cardioprotection.

[The triglyceride-lowering effects of PCSK9 inhibitor differ in patients with different baseline triglyceride levels]

OBJECTIVE

To investigate the triglyceride (TG)-lowering effects of PCSK9 inhibitor in patients with in different baseline triglyceride levels.

METHODS

Between February, 2019 and March, 2020, a total of 59 patients were treated with PCSK9 inhibitor (Evolocumab) in 5 hospitals, including Nanfang Hospital, Guangdong Provincial People's Hospital, First Affiliated Hospital of Sun Yat-sen University, Foshan Nanhai District People's Hospital and Yulin First People's Hospital. According to baseline triglyceride levels, the patients were divided into normal TG group (< 1.70 mmol/L, n=24), mild hypertriglyceridemia group (1.70-2.29 mmol/L, n=11), moderate hypertriglyceridemia group (2.30-5.63 mmol/L, n=13), and severe hypertriglyceridemia group (≥5.64 mmol/L, n=11), and the changes in TG level after the treatment were compared among the 4 groups.

RESULTS

In the groups with normal and mildly elevated baseline TG level, the patients did not show significant changes in TG levels after the treatment. In patients with moderately and severely elevated baseline TG levels, treatment with PCSK9 inhibitor significantly reduced their TG levels (P < 0.005).

CONCLUSIONS

PCSK9 inhibitor has a significant TG-lowering effect in patients with moderate to severe hypertriglyceridemia but not in patients with only mildly elevated baseline TG level.

Prognostic impact of estimated remnant-like particle cholesterol in patients with differing glycometabolic status: an observational cohort study from China

Background

It is uncertain whether estimated remnant-like particle cholesterol (RLP-C) could predict residual risk in patients with different glycometabolic status. This study aimed to evaluate the relationship between estimated RLP-C and adverse prognosis in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) treated with percutaneous coronary intervention (PCI) and to identify the potential impact of glycometabolism on the predictive value of estimated RLP-C.

Methods

The study assessed 2419 participants with NSTE-ACS undergoing PCI at Beijing Anzhen Hospital from January to December 2015. Estimated RLP-C was calculated as follows: total cholesterol (TC) minus low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). The adverse events included all-cause death, non-fatal myocardial infarction (MI), and ischemia-driven revascularization.

Results

Estimated RLP-C was prominently associated with adverse prognosis in the total population [hazard ratio (HR) 1.291 per 1-SD increase, 95% confidence interval (CI) 1.119–1.490, P <  0.001], independent of confounding risk factors. However, subgroup analysis showed that increasing estimated RLP-C was related to a higher risk of adverse events in the diabetic population only [HR 1.385 per 1-SD increase, 95% CI 1.183–1.620, P <  0.001]. Estimated RLP-C failed to be a significant determinant of adverse prognosis in non-diabetic and pre-diabetic subgroups. The addition of estimated RLP-C to a baseline model including traditional risk factors enhanced the predictive performance both in total and diabetic populations.

Conclusions

High estimated RLP-C level is a significant predictor for recurrent adverse events in patients with diabetes and NSTE-ACS treated with PCI.

Circulating Rather Than Intestinal PCSK9 (Proprotein Convertase Subtilisin Kexin Type 9) Regulates Postprandial Lipemia in Mice

OBJECTIVE

Increased postprandial lipemia (PPL) is an independent risk factor for atherosclerotic cardiovascular diseases. PCSK9 (Proprotein convertase subtilisin kexin type 9) is an endogenous inhibitor of the LDLR (low-density lipoprotein receptor) pathway. We previously showed that PCSK9 inhibition in mice reduces PPL. However, the relative contribution of intracellular intestinal PCSK9 or liver-derived circulating PCSK9 to this effect is still unclear. Approach and Results: To address this issue, we generated the first intestine-specific Pcsk9-deficient (i-Pcsk9^-/-) mouse model. PPL was measured in i-Pcsk9^-/- as well as in wild-type and streptozotocin-induced diabetic mice following treatment with a PCSK9 monoclonal antibody (alirocumab). Blocking the circulating form of PCSK9 with alirocumab significantly reduced PPL, while overexpressing human PCSK9 in the liver of full Pcsk9^-/- mice had the opposite effect. Alirocumab regulated PPL in a LDLR-dependent manner as this effect was abolished in Ldlr^-/- mice. In contrast, i-Pcsk9^-/- mice did not exhibit alterations in plasma lipid parameters nor in PPL. Finally, PPL was highly exacerbated by streptozotocin-induced diabetes mellitus in Pcsk9^+/+ but not in Pcsk9^-/- mice, an effect that was mimicked by the use of alirocumab in streptozotocin-treated Pcsk9^+/+ mice.

CONCLUSIONS

Taken together, our data demonstrate that PPL is significantly altered by full but not intestinal PCSK9 deficiency. Treatment with a PCSK9 monoclonal antibody mimics the effect of PCSK9 deficiency on PPL suggesting that circulating PCSK9 rather than intestinal PCSK9 is a critical regulator of PPL. These data validate the clinical relevance of PCSK9 inhibitors to reduce PPL, especially in patients with type 2 diabetes mellitus.

Relationship of Zonulin with Serum PCSK9 Levels after a High Fat Load in a Population of Obese Subjects

Despite the fact that circulating levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) remain unchanged after fat load in healthy lean individuals, PCSK9 has been suggested to have a role in postprandial lipemia regulation in obese individuals. On the other hand, intestinal permeability and endotoxemia have been observed to increase more in obese individuals than in non-obese individuals after a lipid load. This study aimed to analyze the relationship between PCSK9, intestinal permeability, and endotoxemia after a high fat load in obese individuals. We included 39 individuals with morbid obesity. Serum PCSK9 levels, intestinal permeability marker (zonulin), endotoxemia markers (LPS and LBP), and lipid parameters were measured before and after 3 h of fat load. A significant rise in triglycerides, apolipoprotein A1, zonulin, LPS, and LBP, and a significant decline in PCSK9, were observed after a lipid load. Linear regression analysis showed that low-density lipoprotein cholesterol (LDL-C) was independently related to PCSK9 at baseline, whereas both zonulin and LDL-C were independently related to PCSK9 levels after fat load. A relationship between zonulin and PCSK9 levels after fat load in individuals with morbid obesity may exist.

Metabolic effects of PCSK9 inhibition with Evolocumab in subjects with elevated Lp(a)

Background

Epidemiological studies substantiated that subjects with elevated lipoprotein(a) [Lp(a)] have a markedly increased cardiovascular risk. Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) lowers both LDL cholesterol (LDL-C) as well as Lp(a), albeit modestly. Effects of PCSK9 inhibition on circulating metabolites such as lipoprotein subclasses, amino acids and fatty acids remain to be characterized.

Methods

We performed nuclear magnetic resonance (NMR) metabolomics on plasma samples derived from 30 individuals with elevated Lp(a) (> 150 mg/dL). The 30 participants were randomly assigned into two groups, placebo (N = 14) and evolocumab (N = 16). We assessed the effect of 16 weeks of evolocumab 420 mg Q4W treatment on circulating metabolites by running lognormal regression analyses, and compared this to placebo. Subsequently, we assessed the interrelationship between Lp(a) and 14 lipoprotein subclasses in response to treatment with evolocumab, by running multilevel multivariate regression analyses.

Results

On average, evolocumab treatment for 16 weeks resulted in a 17% (95% credible interval: 8 to 26%, P < 0.001) reduction of circulating Lp(a), coupled with substantial reduction of VLDL, IDL and LDL particles as well as their lipid contents. Interestingly, increasing concentrations of baseline Lp(a) were associated with larger reduction in triglyceride-rich VLDL particles after evolocumab treatment.

Conclusions

Inhibition of PCSK9 with evolocumab markedly reduced VLDL particle concentrations in addition to lowering LDL-C. The extent of reduction in VLDL particles depended on the baseline level of Lp(a). Our findings suggest a marked effect of evolocumab on VLDL metabolism in subjects with elevated Lp(a).

Trial registration

Clinical trial registration information is registered at ClinicalTrials.gov on April 14, 2016 with the registration number NCT02729025.

Effect of alirocumab on individuals with type 2 diabetes, high triglycerides, and low high-density lipoprotein cholesterol

BACKGROUND

Mixed dyslipidemia [elevated non-high-density lipoprotein cholesterol (non-HDL-C) and triglycerides (TGs), and decreased HDL-C] is common in type 2 diabetes mellitus (T2DM) and is associated with increased cardiovascular risk. Non-HDL-C and apolipoprotein B (ApoB) are the preferred therapeutic targets for mixed dyslipidemia. Alirocumab is a monoclonal antibody to proprotein convertase subtilisin/kexin type 9 (PCSK9) that effectively reduces low-density lipoprotein cholesterol (LDL-C), non-HDL-C, ApoB, and lipoprotein(a) (Lp[a]), and is well-tolerated in individuals with T2DM.

METHODS

The previously reported open-label ODYSSEY DM-DYSLIPIDEMIA trial data demonstrated the effects of alirocumab on individuals with non-HDL-C ≥ 100 mg/dL and TGs ≥ 150 and < 500 mg/dL receiving stable maximally tolerated statin (n = 413). This post hoc subgroup analysis of the primary trial investigated the effects of alirocumab [75 mg every 2 weeks (Q2W) with possible increase to 150 mg Q2W at Week 12] versus usual care [ezetimibe, fenofibrate, or no additional lipid-lowering therapy (LLT)] on non-HDL-C and other lipids in individuals with T2DM and baseline TGs ≥ 200 mg/dL and HDL-C < 40 mg/dL (men) or < 50 mg/dL (women).

RESULTS

Alirocumab significantly reduced non-HDL-C [LS mean difference (standard error (SE)), - 35.0% (3.9)], ApoB [LS mean difference (SE), - 34.7% (3.6)], LDL-C [LS mean difference (SE), - 47.3% (5.2)], LDL particle number [LS mean difference (SE), - 40.8% (4.1)], and Lp(a) [LS mean difference (SE), - 29.9% (5.4)] versus usual care from baseline to Week 24 (all P < 0.0001). Results were similar for alirocumab versus usual care. TG reductions were similar between alirocumab and usual care (no significant difference), but greater with fenofibrate versus alirocumab (P = 0.3371). Overall, alirocumab significantly increased HDL-C versus usual care [LS mean difference (SE), 7.9% (3.6); P < 0.05], although differences with alirocumab versus ezetimibe or fenofibrate were non-significant. Most individuals receiving alirocumab achieved ApoB < 80 mg/dL (67.9%) and non-HDL-C < 100 mg/dL (60.9%). Adverse event frequency was similar between alirocumab (67.2%) and usual care (70.7%). Additionally, no clinically relevant effect of alirocumab on change in glycemic parameters or use of antihyperglycemic agents was observed.

CONCLUSIONS

Alirocumab is an effective therapeutic option for individuals with T2DM, TGs ≥ 200 mg/dL, and HDL-C < 40 mg/dL (men) or < 50 mg/dL (women). Atherogenic lipid (ApoB and non-HDL) reductions were greater with alirocumab than ezetimibe, fenofibrate, or no LLT. Consistent with previous studies, alirocumab was generally well tolerated. Trial registration Clinicaltrials.gov, NCT02642159. Registered December 24, 2015, https://clinicaltrials.gov/ct2/show/NCT02642159.

The PCSK9 revolution: Current status, controversies, and future directions

Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) has revolutionized our understanding of cholesterol homeostasis and added to our arsenal against atherosclerotic cardiovascular disease (ASCVD). In a span of approximately 15 years, PCSK9 has morphed from an esoteric and rare cause of familial hypercholesterolemia (FH) into the most efficient cholesterol-lowering target ever known, with the completion of two large scale cardiovascular outcome trials showing positive results. Current Food and Drug Administration (FDA) approved modalities to inhibit PCSK9 are in the form of monoclonal antibodies which display an unparalleled degree of low-density lipoprotein cholesterol (LDL-C) lowering and expand upon the notion that lower LDL-C is better for ASCVD risk reduction. However, the accelerated pace of discovery and therapeutic development has left large gaps in our knowledge regarding the physiology and function of PCSK9. The aim of this review is to provide context to the discovery, history, treatment and current status of PCSK9 and its therapeutic inhibitors and highlight areas of controversy and future directions.

Efficacy and safety of proprotein convertase subtilisin/kexin 9 inhibitors in people with diabetes and dyslipidaemia

Diabetic dyslipidaemia, characterized by quantitative, qualitative and kinetic changes in all major circulating lipids, contributes to the increased cardiovascular risk in patients with type 2 diabetes mellitus (T2DM). A promising therapeutic avenue is the inhibition of the proprotein convertase subtilisin kexin 9 (PCSK9) with human monoclonal antibodies (mAbs) that potently reduce plasma low-density lipoprotein cholesterol (LDL-C) levels on top of statin treatment. The aim of this review is to evaluate the efficacy of PCSK9 inhibitors to lower the residual cardiovascular risk of T2DM patients and to discuss the safety of PCSK9 inhibition in these patients. PCSK9 inhibitors potently lower plasma LDL-C levels in T2DM patients and reduce risk for the development of cardiovascular disease. Anti-PCSK9 mAbs are generally not more or less effective in T2DM patients compared to a general high-risk population. Nevertheless, due to their higher cardiovascular risk, the absolute risk reduction of major cardiovascular events is more significant in T2DM patients. This suggests that treatment of T2DM patients with anti-PCSK9 mAbs could be attractive from a cost-effectiveness perspective. Treatment with anti-PCSK9 mAbs did not result in significant treatment-emergent adverse effects. While genetic studies suggest a potential link between PCSK9 inhibition and glucose homeostasis, anti-PCSK9 mAbs did not worsen glycaemic control in T2DM patients, but their safety should be verified after a longer-term follow-up.

Long-term exposure to air pollution raises circulating levels of proprotein convertase subtilisin/kexin type 9 in obese individuals

Aims

Exposure to airborne particulate matter has been consistently associated with early death and increased morbidity, particularly raising the risk of cardiovascular disease. Obesity, one of the leading cardiovascular disease risk factors, increases susceptibility to the adverse effects of particulate matter exposure. Proprotein convertase subtilisin/kexin type 9 has been related to a large number of cardiovascular risk factors, e.g. atherogenic lipoproteins, arterial stiffness and platelet activation. Thus, the present study was aimed at evaluating, in a series of obese individuals, the effects of particulate matter less than 10 µm in diameter (PM10) on proprotein convertase subtilisin/kexin type 9 circulating levels.

Methods and results

In 500 obese subjects, participating in the cross-sectional Susceptibility to Particle Health Effects, miRNAs and Exosomes (SPHERE) study, we evaluated the effects of long- and short-term PM10 exposure on circulating proprotein convertase subtilisin/kexin type 9 levels. In the studied individuals (body mass index: 33.3 ± 5.2 kg/m2) with an annual average PM10 exposure of 40.12 ± 4.71 µg/m3, proprotein convertase subtilisin/kexin type 9 levels were 248.7 ± 78.6 ng/mL. In univariate analysis, PM10 exposure (annual average) was associated with proprotein convertase subtilisin/kexin type 9 levels (β=1.83, standard error = 0.75, p = 0.014). Interestingly, in a multivariable linear regression model, this association was observed only for carriers of lower concentrations of interferon-γ, whereas it was lost in the presence of higher interferon-γ levels. Proprotein convertase subtilisin/kexin type 9 levels were positively associated with the Framingham Risk Score, which was raised by 15.8% for each 100 ng/ml rise of proprotein convertase subtilisin/kexin type 9.

Conclusions

In obese individuals, more sensitive to the damaging effects of environmental air pollution, PM10 exposure positively associates with proprotein convertase subtilisin/kexin type 9 plasma levels especially in those with low levels of interferon-γ. 

The effect of artichoke on lipid profile: A review of possible mechanisms of action

Cardiovascular disease is a highly prevalent issue worldwide, and one of its main manifestations, dyslipidaemia, needs more attention. Cooked artichoke (Cynara scolymus) hearts or artichoke leaf extract (ALE) are believed to be helpful in the treatment of dyslipidaemia. In this narrative review, we provide a brief overview of the potential impact of artichoke consumption on lipid profile. We appraised the Cochrane, MEDLINE and Web of Science databases, and included articles published between 2000 and June 2018 on intervention in humans only. The main potential of ALE administration observed on lipid profile relates to decreased serum LDL, total cholesterol and triglyceride concentrations, although no strong evidence for increasing HDL appears to exist. Evidence suggests that decreases of 8-49 mg/dL for LDL concentration, 12-55 mg/dL for total cholesterol, and 11-51 mg/dL for triglycerides, can be attributed to 2 to 3 g/d of ALE, in which its components luteolin and chlorogenic acid may play a key role. On the other hand, the effects of cooked artichoke hearts can be attributed mainly to its soluble fibres, particularly inulin. Despite the convincing evidence on its health benefits, additional long-term clinical trials are pivotal to fully elucidate the potential effects of ALE administration on positive cardiovascular outcomes.

Plasma PCSK9 correlates with apoB-48-containing triglyceride-rich lipoprotein production in men with insulin resistance

Intestinal triglyceride (TG)-rich lipoproteins (TRLs) are important in the pathogenesis of atherosclerosis in insulin resistance (IR). We investigated the association of plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) concentrations with apoB-48-containing TRL metabolism in 148 men displaying various degrees of IR by measuring in vivo kinetics of TRL apoB-48 during a constant-fed state after a primed-constant infusion of L-[5,5,5-D3]leucine. Plasma PCSK9 concentrations positively correlated with TRL apoB-48 pool size (r = 0.31, P = 0.0002) and production rate (r = 0.24, P = 0.008) but not the fractional catabolic rate (r = -0.04, P = 0.6). Backward stepwise multiple linear regression analysis identified PCSK9 concentrations as a positive predictor of TRL apoB-48 production rate (standard β = +0.20, P = 0.007) independent of BMI, age, T2D/metformin use, dietary fat intake during the kinetic study, and fasting concentrations of TGs, insulin, glucose, LDL cholesterol, or C-reactive protein. We also assessed intestinal expression of key genes involved in chylomicron processing from duodenal samples of 71 men. Expression of PCSK9 and HMG-CoAR genes was positively associated (r = 0.43, P = 0.002). These results support PCSK9 association with intestinal secretion and plasma overaccumulation of TRL apoB-48 in men with IR.