Reconstituted High-Density Lipoprotein Attenuates Platelet Function in Individuals With Type 2 Diabetes Mellitus by Promoting Cholesterol Efflux

Effect of Reconstituted Human Apolipoprotein A-I on Recurrent Ischemic Events in Survivors of Acute MI

BACKGROUND

The AEGIS-II trial hypothesized that CSL112, an intravenous formulation of human apoA-I, would lower the risk of plaque disruption, decreasing the risk of recurrent events such as myocardial infarction (MI) among high-risk patients with MI.

OBJECTIVES

This exploratory analysis evaluates the effect of CSL112 therapy on the incidence of cardiovascular (CV) death and recurrent MI.

METHODS

The AEGIS-II trial was an international, multicenter, randomized, double-blind, placebo-controlled trial that randomized 18,219 high-risk acute MI patients to 4 weekly infusions of apoA-I (6 g CSL112) or placebo.

RESULTS

The incidence of the composite of CV death and type 1 MI was 11% to 16% lower in the CSL112 group over the study period (HR: 0.84; 95% CI: 0.7-1.0; P = 0.056 at day 90; HR: 0.86; 95% CI: 0.74-0.99; P = 0.048 at day 180; and HR: 0.89; 95% CI: 0.79-1.01; P = 0.07 at day 365). Similarly, the incidence of CV death or any MI was numerically lower in CSL112-treated patients throughout the follow-up period (HR: 0.92; 95% CI: 0.80-1.05 at day 90, HR: 0.89; 95% CI: 0.79-0.996 at day 180, HR: 0.91; 95% CI: 0.83-1.01 at day 365). The effect of CSL112 treatment on MI was predominantly observed for type 1 MI and type 4b (MI due to stent thrombosis).

CONCLUSIONS

Although CSL112 did not significantly reduce the occurrence of the primary study endpoints, patients treated with CSL112 infusions had numerically lower rates of CV death and MI, type-1 MI, and stent thrombosis-related MI compared with placebo. These findings could suggest a role of apoA-I in reducing subsequent plaque disruption events via enhanced cholesterol efflux. Further prospective data would be needed to confirm these observations.

ANGPTL3 is a novel HDL component that regulates HDL function

BACKGROUND

Angiopoietin-like protein 3 (ANGPTL3) is secreted by hepatocytes and inhibits lipoprotein lipase and endothelial lipase activity. Previous studies reported the correlation between plasma ANGPTL3 levels and high-density lipoprotein (HDL). Recently ANGPTL3 was found to preferentially bind to HDL in healthy human circulation. Here, we examined whether ANGPTL3, as a component of HDL, modulates HDL function and affects HDL other components in human and mice with non-diabetes or type 2 diabetes mellitus.

METHODS

HDL was isolated from the plasma of female non-diabetic subjects and type-2 diabetic mellitus (T2DM) patients. Immunoprecipitation, western blot, and ELISA assays were used to examine ANGPTL3 levels in HDL. Db/m and db/db mice, AAV virus mediated ANGPTL3 overexpression and knockdown models and ANGPTL3 knockout mice were used. The cholesterol efflux capacity induced by HDL was analyzed in macrophages preloaded with fluorescent cholesterol. The anti-inflammation capacity of HDL was assessed using flow cytometry to measure VCAM-1 and ICAM-1 expression levels in TNF-α-stimulated endothelial cells pretreated with HDL.

RESULTS

ANGPTL3 was found to bind to HDL and be a component of HDL in both non-diabetic subjects and T2DM patients. Flag-ANGPTL3 was found in the HDL of transgenic mice overexpressing Flag-ANGPTL3. ANGPLT3 of HDL was positively associated with cholesterol efflux in female non-diabetic controls (r = 0.4102, p = 0.0117) but not in female T2DM patients (r = - 0.1725, p = 0.3224). Lower ANGPTL3 levels of HDL were found in diabetic (db/db) mice compared to control (db/m) mice and were associated with reduced cholesterol efflux and inhibition of VCAM-1 and ICAM-1 expression in endothelial cells (p < 0.05 for all). Following AAV-mediated ANGPTL3 cDNA transfer in db/db mice, ANGPTL3 levels were found to be increased in HDL, and corresponded to increased cholesterol efflux and decreased ICAM-1 expression. In contrast, knockdown of ANGPTL3 levels in HDL by AAV-mediated shRNA transfer led to a reduction in HDL function (p < 0.05 for both). Plasma total cholesterol, total triglycerides, HDL-c, protein components of HDL and the cholesterol efflux function of HDL were lower in ANGPTL3-/- mice than ANGPTL3+/+ mice, suggesting that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL.

CONCLUSION

ANGPTL3 was identified as a component of HDL in humans and mice. ANGPTL3 of HDL regulated cholesterol efflux and the anti-inflammatory functions of HDL in T2DM mice. Both the protein components of HDL and cholesterol efflux capacity of HDL were decreased in ANGPTL3-/- mice. Our findings suggest that ANGPTL3 in HDL may regulate HDL function by disrupting the balance of protein components in HDL. Our study contributes to a more comprehensive understanding of the role of ANGPTL3 in lipid metabolism.

Clot or Not? Reviewing the Reciprocal Regulation Between Lipids and Blood Clotting

Both hyperlipidemia and thrombosis contribute to the risks of atherosclerotic cardiovascular diseases, which are the leading cause of death and reduced quality of life in survivors worldwide. The accumulation of lipid-rich plaques on arterial walls eventually leads to the rupture or erosion of vulnerable lesions, triggering excessive blood clotting and leading to adverse thrombotic events. Lipoproteins are highly dynamic particles that circulate in blood, carry insoluble lipids, and are associated with proteins, many of which are involved in blood clotting. A growing body of evidence suggests a reciprocal regulatory relationship between blood clotting and lipid metabolism. In this review article, we summarize the observations that lipoproteins and lipids impact the hemostatic system, and the clotting-related proteins influence lipid metabolism. We also highlight the gaps that need to be filled in this area of research.

A decreased level of high-density lipoprotein is a possible risk factor for type 2 diabetes mellitus: A review

Introduction

Type 2 diabetes mellitus (T2DM) is characterized primarily by dyslipidemia and hyperglycemia due to insulin resistance. High-density lipoprotein (HDL) play a significant role in preventing the incidence of dyslipidemia and its complications. HDL has different protective functions, such as reducing oxidation, vascular inflammation, and thrombosis; additionally, its anti-diabetic role is one of the most significant recent discoveries about HDL and some of its constituent lipoproteins.

Methods

This research reviews ongoing studies and preliminary investigations into the assessment of relation between decreased level of HDL and T2DM.

Results

The levels of HDL and its functions contribute to glucose hemostasis and the development of T2DM through four possible mechanisms, including insulin secretion by beta cells, peripheral insulin sensitivity, non-insulin-dependent glucose uptake, and adipose tissue metabolic activity. Additionally, the anti-oxidant properties of HDL protect beta cells from apoptosis caused by oxidative stress and inflammation induced by low-density lipoprotein, which facilitate insulin secretion.

Conclusion

Therefore, HDL and its compositions, especially Apo A-I, play an important role in regulating glucose metabolism, and decreased levels of HDL can be considered a risk factor for DM. Different factors, such as hypoalphalipoproteinemia that manifests as a consequence of genetic factors, such as Apo A-I deficiency, as well as secondary causes arising from lifestyle choices and underlying medical conditions that decrease the level of HDL, could be associated with DM. Moreover, intricate connections between HDL and diabetic complications extend beyond glucose metabolism to encompass complications like cardiovascular disease and kidney disease. Therefore, the exact interactions between HDL level and DM should be evaluated in future studies.

Residual risks and evolving atherosclerotic plaques

Atherosclerotic disease of the coronary and carotid arteries is the primary global cause of significant mortality and morbidity. The chronic occlusive diseases have changed the epidemiological landscape of health problems both in developed and the developing countries. Despite the enormous benefit of advanced revascularization techniques, use of statins, and successful attempts of targeting modifiable risk factors, like smoking and exercise in the last four decades, there is still a definite "residual risk" in the population, as evidenced by many prevalent and new cases every year. Here, we highlight the burden of the atherosclerotic diseases and provide substantial clinical evidence of the residual risks in these diseases despite advanced management settings, with emphasis on strokes and cardiovascular risks. We critically discussed the concepts and potential underlying mechanisms of the evolving atherosclerotic plaques in the coronary and carotid arteries. This has changed our understanding of the plaque biology, the progression of unstable vs stable plaques, and the evolution of plaque prior to the occurrence of a major adverse atherothrombotic event. This has been facilitated using intravascular ultrasound, optical coherence tomography, and near-infrared spectroscopy in the clinical settings to achieve surrogate end points. These techniques are now providing exquisite information on plaque size, composition, lipid volume, fibrous cap thickness and other features that were previously not possible with conventional angiography.

Higher HDL-C levels attenuated the association of plasma polybrominated diphenyl ethers with prediabetes and type 2 diabetes mellitus in rural Chinese adults

BACKGROUND

Plasma polybrominated diphenyl ethers (PBDE) were used as flame retardants widely, however, epidemiological evidence for the association between PBDEs and type 2 diabetes mellitus (T2DM) is inconsistent. Moreover, the combined effects of PBDEs and blood lipid indicators on impaired fasting glucose (IFG) and T2DM remains largely unknown in rural areas lacking good waste recycling infrastructure.

METHODS

In this study, a total of 2607 subjects aged 18-79 years were included from the Henan Rural Cohort. Generalized linear and logistic regression models were applied to evaluate the associations of various PBDE pollutants on IFG and T2DM. Quantile g-computation regression and PBDE pollution score created by the adaptive elastic net were applied to evaluate the impact of PBDEs mixtures on IFG and T2DM. Interaction effects of individual PBDE pollutants and blood lipid indicators on IFG and T2DM were assessed by using Interaction plots.

RESULTS

The geometric mean concentrations (detection rates) were 0.09 ng/mL (100.0%), 0.12 ng/mL (97.8%), 0.22 ng/mL (94.7%), 0.16 ng/mL (99.2%) and 0.28 ng/mL (100.0%) for PBDE-28, PBDE-47, PBDE-99, and PBDE-153 respectively. However, PBDE-28, PBDE-99, PBDE-100, and ΣPBDEs were positively associated with IFG (odds ratios (ORs) (95% confidence intervals (CIs)): 1.14 (1.06, 1.23), 1.16 (1.04, 1.29), 1.25 (1.14, 1.37), and 1.27 (1.08, 1.50)). Similarly, PBDE-28, PBDE-47, PBDE-99, PBDE-100, and ΣPBDEs were positively associated with T2DM (ORs (95% CIs): 1.30 (1.10, 1.54), 1.13 (1.06, 1.22), 1.27 (1.13, 1.43), 1.27 (1.15, 1.40), and 1.30 (1.10, 1.54)). Moreover, five PBDE mixtures or jointly as PBDE pollution score, were significantly associated with an increased risk of T2DM (P < 0.05 for all). In addition, the harmful effect of PBDE exposure on T2DM was decreased with accompanying high-density lipoprotein cholesterol (HDL-C) levels increased.

CONCLUSIONS

Our findings highlight the importance of managing PBDEs contamination and suggest that HDL-C may be a novel way to prevent T2DM.

Inverse Correlation of Cholesterol Efflux Capacity with Peripheral Plaque Volume Measured by 3D Ultrasound

INTRODUCTION

Cardiovascular disease (CVD) is a systemic multifocal illness called atherosclerosis that causes artery constriction and blockage. By causing cholesterol to build up in the artery wall, hypercholesterolemia is a major factor in the pathophysiology of atherosclerotic plaque development. Reverse cholesterol transport is the process of transporting cholesterol from the periphery back to the liver through cholesterol efflux mediated by high-density lipoprotein (HDL). It was suggested that the cholesterol efflux capacity (CEC), which is inversely linked with cardiovascular risk, can serve as a stand-in measure for reverse cholesterol transport. In this work, we sought to investigate a potential link between the peripheral plaque volume (PV) and CEC.

METHODS

Since lipid-lowering therapy interferes with CEC, we performed a cross-sectional study of 176 patients (48.9% females) with one cardiovascular risk factor or known CVD that did not currently take lipid-lowering medication. CEC was determined using cAMP-treated ³H-cholesterol-labeled J774 cells. Cholesterol ester transfer protein (CETP)-mediated cholesterol ester transfer was measured by quantifying the transfer of cholesterol ester from radiolabeled exogenous HDL cholesterol to Apolipoprotein B-containing lipoproteins. PV in the carotid and the femoral artery, defined as the total PV, was measured using a 3D ultrasound system equipped with semi-automatic software.

RESULTS

In our patients, we discovered an inverse relationship between high total PV and CEC (p = 0.027). However, there was no connection between total PV and low-density lipoprotein cholesterol, lipoprotein (a), or CETP-mediated cholesterol ester transfer.

CONCLUSION

In patients not receiving lipid-lowering treatment, CEC inversely correlates with peripheral atherosclerosis, supporting its role in the pathophysiology of atherosclerosis.

A Current Update on the Role of HDL-Based Nanomedicine in Targeting Macrophages in Cardiovascular Disease

High-density lipoproteins (HDL) are complex endogenous nanoparticles involved in important functions such as reverse cholesterol transport and immunomodulatory activities, ensuring metabolic homeostasis and vascular health. The ability of HDL to interact with a plethora of immune cells and structural cells places it in the center of numerous disease pathophysiologies. However, inflammatory dysregulation can lead to pathogenic remodeling and post-translational modification of HDL, rendering HDL dysfunctional or even pro-inflammatory. Monocytes and macrophages play a critical role in mediating vascular inflammation, such as in coronary artery disease (CAD). The fact that HDL nanoparticles have potent anti-inflammatory effects on mononuclear phagocytes has opened new avenues for the development of nanotherapeutics to restore vascular integrity. HDL infusion therapies are being developed to improve the physiological functions of HDL and to quantitatively restore or increase the native HDL pool. The components and design of HDL-based nanoparticles have evolved significantly since their initial introduction with highly anticipated results in an ongoing phase III clinical trial in subjects with acute coronary syndrome. The understanding of mechanisms involved in HDL-based synthetic nanotherapeutics is critical to their design, therapeutic potential and effectiveness. In this review, we provide a current update on HDL-ApoA-I mimetic nanotherapeutics, highlighting the scope of treating vascular diseases by targeting monocytes and macrophages.

Clinical Pharmacokinetics and Pharmacodynamics of CSL112

Cardiovascular diseases are the leading cause of death worldwide. Although there have been substantial advances over the last decades, recurrent adverse cardiovascular events after myocardial infarction are still frequent, particularly during the first year of the index event. For decades, high-density lipoprotein (HDL) has been among the therapeutic targets for long-term prevention after an ischemic event. However, early trials focusing on increasing HDL circulating levels showed no improvement in clinical outcomes. Recently, the paradigm has shifted to increasing the functionality of HDL rather than its circulating plasma levels. For this purpose, apolipoprotein-AI-based infusion therapies have been developed, including reconstituted HDL, such as CSL112. During the last decade, CSL112 has been extensively studied in Phase 1 and 2 trials and has shown promising results. In particular, CSL112 has been studied in the Phase 2b AEGIS trial exhibiting good safety and tolerability profiles, which has led to the ongoing large-scale Phase 3 AEGIS-II trial. This systematic overview will provide a comprehensive summary of the CSL112 drug development program focusing on its pharmacodynamic, pharmacokinetic, and safety profiles.

Ganglioside GM3-Functionalized Reconstituted High-Density Lipoprotein (GM3-rHDL) as a Novel Nanocarrier Enhances Antiatherosclerotic Efficacy of Statins in apoE-/- C57BL/6 Mice

Previously, we found that exogenous ganglioside GM3 had an antiatherosclerotic efficacy and that its antiatherosclerotic efficacy could be enhanced by reconstituted high-density lipoprotein (rHDL). In this study, we hypothesized that GM3-functionalized rHDL (i.e., GM3-rHDL) as a nanocarrier can promote the efficacy of traditional antiatherosclerotic drugs (e.g., statins). To test this hypothesis, lovastatin (LT) was used as a representative of statins, and LT-loaded GM3-rHDL nanoparticle (LT-GM3-rHDL or LT@GM3-rHDL; a mean size of ~142 nm) and multiple controls (e.g., GM3-rHDL without LT, LT-loaded rHDL or LT-rHDL, and other nanoparticles) were prepared. By using two different microsphere-based methods, the presences of apolipoprotein A-I (apoA-I) and/or GM3 in nanoparticles and the apoA-I-mediated macrophage-targeting ability of apoA-I/rHDL-containing nanoparticles were verified in vitro. Moreover, LT-GM3-rHDL nanoparticle had a slowly sustained LT release in vitro and the strongest inhibitory effect on the foam cell formation of macrophages (a key event of atherogenesis). After single administration of rHDL-based nanoparticles, a higher LT concentration was detected shortly in the atherosclerotic plaques of apoE^-/- mice than non-rHDL-based nanoparticles, suggesting the in vivo plaque-targeting ability of apoA-I/rHDL-containing nanoparticles. Finally, among all nanoparticles LT-GM3-rHDL induced the largest decreases in the contents of blood lipids and in the areas of atherosclerotic plaques at various aortic locations in apoE^-/- mice fed a high-fat diet for 12 weeks, supporting that LT-GM3-rHDL has the best in vivo antiatherosclerotic efficacy among the tested nanoparticles. Our data imply that GM3-functionalized rHDL (i.e., GM3-rHDL) can be utilized as a novel nanocarrier to enhance the efficacy of traditional antiatherosclerotic drugs (e.g., statins).

Apolipoprotein A-I, elevated in trauma patients, inhibits platelet activation and decreases clot strength

Apolipoprotein A-I (ApoA-I) is elevated in the plasma of a subgroup of trauma patients with systemic hyperfibrinolysis. We hypothesize that apoA-I inhibits platelet activation and clot formation. The effects of apoA-I on human platelet activation and clot formation were assessed by whole blood thrombelastography (TEG), platelet aggregometry, P-selectin surface expression, microfluidic adhesion, and Akt phosphorylation. Mouse models of carotid artery thrombosis and pulmonary embolism were used to assess the effects of apoA-I in vivo. The ApoA-1 receptor was investigated with transgenic mice knockouts (KO) for the scavenger receptor class B member 1 (SR-BI). Compared to controls, exogenous human apoA-I inhibited arachidonic acid and collagen-mediated human and mouse platelet aggregation, decreased P-selectin surface expression and Akt activation, resulting in diminished clot strength and increased clot lysis by TEG. ApoA-I also decreased platelet aggregate size formed on a collagen surface under flow. In vivo, apoA-I delayed vessel occlusion in an arterial thrombosis model and conferred a survival advantage in a pulmonary embolism model. SR-BI KO mice significantly reduced apoA-I inhibition of platelet aggregation versus wild-type platelets. Exogenous human apoA-I inhibits platelet activation, decreases clot strength and stability, and protects mice from arterial and venous thrombosis via the SR-BI receptor.

Beneficial effects of high-density lipoprotein (HDL) on stent biocompatibility and the potential value of HDL infusion therapy following percutaneous coronary intervention

Several epidemiological studies have shown a clear inverse relationship between serum levels of high-density lipoprotein cholesterol (HDL-C) and the risk of atherosclerotic cardiovascular disease (ASCVD), even at low-density lipoprotein cholesterol levels below 70 mg/dL. There is much evidence from basic and clinical studies that higher HDL-C levels are beneficial, whereas lower HDL-C levels are detrimental. Thus, HDL is widely recognized as an essential anti-atherogenic factor that plays a protective role against the development of ASCVD. Percutaneous coronary intervention is an increasingly common treatment choice to improve myocardial perfusion in patients with ASCVD. Although drug-eluting stents have substantially overcome the limitations of conventional bare-metal stents, there are still problems with stent biocompatibility, including delayed re-endothelialization and neoatherosclerosis, which cause stent thrombosis and in-stent restenosis. According to numerous studies, HDL not only protects against the development of atherosclerosis, but also has many anti-inflammatory and vasoprotective properties. Therefore, the use of HDL as a therapeutic target has been met with great interest. Although oral medications have not shown promise, the developed HDL infusions have been tested in clinical trials and have demonstrated viability and reproducibility in increasing the cholesterol efflux capacity and decreasing plasma markers of inflammation. The aim of the present study was to review the effect of HDL on stent biocompatibility in ASCVD patients following implantation and discuss a novel therapeutic direction of HDL infusion therapy that may be a promising candidate as an adjunctive therapy to improve stent biocompatibility following percutaneous coronary intervention.

CYP2C19 polymorphisms and lipoproteins associated with clopidogrel resistance in children with Kawasaki disease in China: A prospective study

Background

CYP2C19 genetic variation and clinical factors have been proved to be related with clopidogrel resistance (CR) in adults, while the presence of CR in children with Kawasaki disease (KD) was seldom reported. Our objective was to evaluate KD patients’ response to clopidogrel treatment and determine whether CYP2C19 gene polymorphisms and laboratory indicators are associated with CR in this population.

Methods

This was a prospective and single-center study. We recruited children with KD hospitalized in the cardiology department at the Children’s Hospital Capital Institute of Pediatrics between January 2019 and October 2021, and the distribution of the CYP2C19 gene polymorphisms was assessed. According to the light transmission aggregometry (LTA) test results, KD patients who were treated with clopidogrel were divided into CR group and non-CR (NCR) group. We also analyzed the influence of CYP2C19 gene polymorphisms and laboratory indicators on CR in children with KD.

Results

(1) A total of 346 children with KD were evaluated for the genotypic and phenotypic distributions of CYP2C19. Loss-of-function (LOF) mutated allele was included in 56.9% of CYP2C19 genotypes, and their corresponding phenotypes were intermediate metabolizers (46.2%) and poor metabolizers (10.7%). (2) The incidence of CR in this study population was 31.4%. The multivariate logistic regression showed that carrying CYP2C19 LOF allele (OR, 3.922; 95%CI, 1.504–10.282; P = 0.005) and high levels of low-density lipoprotein (OR, 1.675; 95%CI, 1.069–2.623; P = 0.024) were independent risk factor for CR, while low levels of high-density lipoprotein (OR, 0.120; 95%CI, 0.020, 0.734; P = 0.022) was an independent protective factor for CR. The area under the receiver operator characteristic curve of the multivariate logistic regression model (including high-density lipoprotein, low-density lipoprotein, and CYP2C19 LOF allele carriers) for predicting CR was 0.769 (95% CI, 0.674–0.863; P < 0.001). The sensitivity and specificity were 70.3 and 74.0%, respectively.

Conclusion

Carrying CYP2C19 LOF allele, low levels of high-density lipoprotein, and high levels of low-density lipoprotein were independent risk factors for CR in children with KD in China. This may benefit pediatricians in choosing appropriate individualized antiplatelet therapy.

Mechanism and Potential Target of Blood-Activating Chinese Botanical Drugs Combined With Anti-Platelet Drugs: Prevention and Treatment of Atherosclerotic Cardiovascular Diseases

Atherosclerotic cardiovascular diseases (ASCVDs) are the most important diseases that endanger people’s health, leading to high morbidity and mortality worldwide. In addition, various thrombotic events secondary to cardiovascular and cerebrovascular diseases need must be considered seriously. Therefore, the development of novel anti-platelet drugs with high efficiency, and fewer adverse effects has become a research focus for preventing of cardiovascular diseases (CVDs). Blood-activation and stasis-removal from circulation have been widely considered as principles for treating syndromes related to CVDs. Blood-activating Chinese (BAC botanical drugs, as members of traditional Chinese medicine (TCM), have shown to improve hemodynamics and hemorheology, and inhibit thrombosis and atherosclerosis. Modern medical research has identified that a combination of BAC botanical drugs and anti-platelet drugs, such as aspirin or clopidogrel, not only enhances the anti-platelet effects, but also reduces the risk of bleeding and protects the vascular endothelium. The anti-platelet mechanism of Blood-activating Chinese (BAC) botanical drugs and their compounds is not clear; therefore, their potential targets need to be explored. With the continuous development of bioinformatics and “omics” technology, some unconventional applications of BAC botanical drugs have been discovered. In this review, we will focus on the related targets and signaling pathways of anti-atherosclerotic treatments involving a combination of BAC botanical drugs and anti-platelet drugs reported in recent years.

Stent-based delivery of AAV2 vectors encoding oxidation-resistant apoA1

In-stent restenosis (ISR) complicates revascularization in the coronary and peripheral arteries. Apolipoprotein A1 (apoA1), the principal protein component of HDL possesses inherent anti-atherosclerotic and anti-restenotic properties. These beneficial traits are lost when wild type apoA1(WT) is subjected to oxidative modifications. We investigated whether local delivery of adeno-associated viral (AAV) vectors expressing oxidation-resistant apoA1(4WF) preserves apoA1 functionality. The efflux of 3H-cholesterol from macrophages to the media conditioned by endogenously produced apoA1(4WF) was 2.1-fold higher than for apoA1(WT) conditioned media in the presence of hypochlorous acid emulating conditions of oxidative stress. The proliferation of apoA1(WT)- and apoA1(4FW)-transduced rat aortic smooth muscle cells (SMC) was inhibited by 66% ± 10% and 65% ± 11%, respectively, in comparison with non-transduced SMC (p < 0.001). Conversely, the proliferation of apoA1(4FW)-transduced, but not apoA1(WT)-transduced rat blood outgrowth endothelial cells (BOEC) was increased 41% ± 5% (p < 0.001). Both apoA1 transduction conditions similarly inhibited basal and TNFα-induced reactive oxygen species in rat aortic endothelial cells (RAEC) and resulted in the reduced rat monocyte attachment to the TNFα-activated endothelium. AAV2-eGFP vectors immobilized reversibly on stainless steel mesh surfaces through the protein G/anti-AAV2 antibody coupling, efficiently transduced cells in culture modeling stent-based delivery. In vivo studies in normal pigs, deploying AAV2 gene delivery stents (GDS) preloaded with AAV2-eGFP in the coronary arteries demonstrated transduction of the stented arteries. However, implantation of GDS formulated with AAV2-apoA1(4WF) failed to prevent in-stent restenosis in the atherosclerotic vasculature of hypercholesterolemic diabetic pigs. It is concluded that stent delivery of AAV2-4WF while feasible, is not effective for mitigation of restenosis in the presence of severe atherosclerotic disease.

First Recombinant High-Density Lipoprotein Particles Administration in a Severe ICU COVID-19 Patient, a Multi-Omics Exploratory Investigation

High-density lipoproteins (HDLs) have multiple endothelioprotective properties. During SARS-CoV-2 infection, HDL-cholesterol (HDL-C) concentration is markedly reduced, and studies have described severe impairment of the functionality of HDL particles. Here, we report a multi-omic investigation of the first administration of recombinant HDL (rHDL) particles in a severe COVID-19 patient in an intensive care unit. Plasma ApoA1 increased and HDL-C decreased after each recombinant HDL injection, suggesting that these particles were functional in terms of reverse cholesterol transport. The proportion of large HDL particles also increased after injection of recombinant HDL. Shotgun proteomics performed on HDLs isolated by ultracentrifugation indicated that ApoA1 was more abundant after injections whereas most of the pro-inflammatory proteins identified were less abundant. Assessment of Serum amyloid A-1, inflammatory markers, and cytokines showed a significant decrease for most of them during recombinant HDL infusion. Our results suggest that recombinant HDL infusion is feasible and a potential therapeutic strategy to be explored in COVID-19 patients.

HDL maturation and remodelling

Cholesterol in the circulation is mostly transported in an esterified form as a component of lipoproteins. The majority of these cholesteryl esters are produced in nascent, discoidal high density lipoproteins (HDLs) by the enzyme, lecithin:cholesterol acyltransferase (LCAT). Discoidal HDLs are discrete populations of particles that consist of a phospholipid bilayer, the hydrophobic acyl chains of which are shielded from the aqueous environment by apolipoproteins that also confer water solubility on the particles. The progressive LCAT-mediated accumulation of cholesteryl esters in discoidal HDLs generates the spherical HDLs that predominate in normal human plasma. Spherical HDLs contain a core of water insoluble, neutral lipids (cholesteryl esters and triglycerides) that is surrounded by a surface monolayer of phospholipids with which apolipoproteins associate. Although spherical HDLs all have the same basic structure, they are extremely diverse in size, composition, and function. This review is concerned with how the biogenesis of discoidal and spherical HDLs is regulated and the mechanistic basis of their size and compositional heterogeneity. Current understanding of the impact of this heterogeneity on the therapeutic potential of HDLs of varying size and composition is also addressed in the context of several disease states.

The Role of Changes in Cumulative Lipid Parameter Burden in the Pathogenesis of Type 2 Diabetes Mellitus: A Cohort Study of People Aged 35-65 Years in Rural China

PURPOSE

The main purpose of this study was to examine the effect of the cumulative exposure of blood lipid parameters on type 2 diabetes mellitus (T2DM). Another purpose was to explore whether the cumulative burden of blood lipid parameters plays a certain role in the pathogenesis of diet affecting T2DM.

PATIENTS AND METHODS

A total of 63 cases of diabetes occurred from 2017 to 2020, with an incidence density of 3.71 person-years. The dietary intake of the residents was obtained by using a dietary frequency questionnaire (FFQ). Cumulative lipid parameter burden was calculated according to the number of years (2016-2020) multiplied by total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL) and triglyceride (TG). A Cox proportional hazard model was used to estimate the effect of cumulative lipid burden on T2DM. A mediating analysis of accelerated failure time (AFT) was used to investigate the mediating effects of certain foods, the cumulative lipid parameter burden and T2DM.

RESULTS

A higher cumulative TG load corresponded to a higher risk of T2DM onset (P_trend =0.021). After adjusting for covariates, the highest quartile cumulative TG burden had a 3.462 times higher risk of T2DM than that in the lowest quartile (HR=3.462, 95% CI: 1.297-9.243). Moreover, a higher cumulative HDL load corresponded to a lower risk of T2DM onset (P_trend =0.006). After adjusting for covariates, the risk of T2DM was 0.314-fold lower in the highest quartile of cumulative HDL burden than that in the lowest quartile (HR=0.314, 95% CI: 0.131-0.753). Cumulative TG burden partially mediated the association between red meat and T2DM.

CONCLUSION

The increase in cumulative HDL burden and the decrease in cumulative HDL burden are related to the incidence of T2DM. Cumulative TG burden was shown to play a partial mediating role in the pathogenesis of red meat and diabetes.

HDL and type 2 diabetes: the chicken or the egg?

HDL is a complex macromolecular cluster of various components, such as apolipoproteins, enzymes and lipids. Quality evidence from clinical and epidemiological studies led to the principle that HDL-cholesterol (HDL-C) levels are inversely correlated with the risk of CHD. Nevertheless, the failure of many cholesteryl ester transfer protein inhibitors to protect against CVD casts doubts on this principle and highlights the fact that HDL functionality, as dictated by its proteome and lipidome, also plays an important role in protecting against metabolic disorders. Recent data indicate that HDL-C levels and HDL particle functionality are correlated with the pathogenesis and prognosis of type 2 diabetes mellitus, a major risk factor for CVD. Hyperglycaemia leads to reduced HDL-C levels and deteriorated HDL functionality, via various alterations in HDL particles' proteome and lipidome. In turn, reduced HDL-C levels and impaired HDL functionality impact the performance of key organs related to glucose homeostasis, such as pancreas and skeletal muscles. Interestingly, different structural alterations in HDL correlate with distinct metabolic abnormalities, as indicated by recent data evaluating the role of apolipoprotein A1 and lecithin-cholesterol acyltransferase deficiency in glucose homeostasis. While it is becoming evident that not all HDL disturbances are causatively associated with the development and progression of type 2 diabetes, a bidirectional correlation between these two conditions exists, leading to a perpetual self-feeding cycle.

Treatment with PCSK9 Inhibitors in Patients with Familial Hypercholesterolemia Lowers Plasma Levels of Platelet-Activating Factor and Its Precursors: A Combined Metabolomic and Lipidomic Approach

INTRODUCTION

Familial hypercholesterolemia (FH) is characterized by extremely high levels of circulating low-density lipoprotein cholesterol (LDL-C) and is caused by mutations of genes involved in LDL-C metabolism, including LDL receptor (LDLR), apolipoprotein B (APOB), or proprotein convertase subtilisin/Kexin type 9 (PCSK9). Accordingly, PCSK9 inhibitors (PCSK9i) are effective in LDL-C reduction. However, no data are available on the pleiotropic effect of PCSK9i. To this end, we performed an untargeted metabolomics approach to gather a global view on changes in metabolic pathways in patients receiving treatment with PCSK9i.

METHODS

Twenty-five FH patients starting treatment with PCSK-9i were evaluated by an untargeted metabolomics approach at baseline (before PCSK9i treatment) and after 12 weeks of treatment.

RESULTS

All the 25 FH subjects enrolled were on maximal tolerated lipid-lowering therapy prior to study entry. After a 12 week treatment with PCSK9i, we observed an expected significant reduction in LDL-cholesterol levels (from 201.0 ± 69.5 mg/dL to 103.0 ± 58.0 mg/dL, p < 0.001). The LDL-C target was achieved in 36% of patients. After peak validation and correction, after 12 weeks of PCSK9i treatment as compared to baseline, we observed increments in creatine (p-value = 0.041), indole (p-value = 0.045), and indoleacrylic acid (p-value= 0.045) concentrations. Conversely, significant decreases in choline (p-value = 0.045) and phosphatidylcholine (p-value < 0.01) together with a reduction in platelet activating factor (p-value = 0.041) were observed.

CONCLUSIONS

Taking advantage of untargeted metabolomics, we first provided evidence of concomitant reductions in inflammation and platelet activation metabolites in FH patients receiving a 12 week treatment with PCSK9i.

High-density lipoprotein in Alzheimer's disease: From potential biomarkers to therapeutics

The inverse correlation between high-density lipoprotein (HDL) levels in vivo and the risk of Alzheimer's disease (AD) has become an inspiration for HDL-inspired AD therapy, including plain HDL and various intelligent HDL-based drug delivery systems. In this review, we will focus on the two endogenous HDL subtypes in the central nervous system (CNS), apolipoprotein E-based HDL (apoE-HDL) and apolipoprotein A-I-based HDL (apoA-I-HDL), especially their influence on AD pathophysiology to reveal HDL's potential as biomarkers for risk prediction, and summarize the relevant therapeutic mechanisms to propose possible treatment strategies. We will emphasize the latest advances of HDL as therapeutics (plain HDL and HDL-based drug delivery systems) to discuss the potential for AD therapy and review innovative techniques in the preparation of HDL-based nanoplatforms to provide a basis for the rational design and future development of anti-AD drugs.

Dose-Response Association Between High-Density Lipoprotein Cholesterol and Stroke: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

INTRODUCTION

Studies investigating the effect of high-density lipoprotein cholesterol (HDL-C) on stroke and stroke subtypes have reached inconsistent conclusions. The purpose of our study was to clarify the dose-response association between HDL-C level and risk of total stroke and stroke subtypes by a systematic review and meta-analysis.

METHODS

We performed a systematic search of PubMed, Embase, and Web of Science databases through July 30, 2020, for prospective cohort studies that reported the HDL-C-stroke association and extracted the estimate that was adjusted for the greatest number of confounding factors. Restricted cubic splines were used to evaluate the linear and nonlinear dose-response associations.

RESULTS

We included 29 articles, which reported on 62 prospective cohort studies including 900,501 study participants and 25,678 with stroke. The summary relative risk per 1-mmol/L increase in HDL-C level for total stroke was 0.82 (95% CI, 0.76-0.89; I² = 42.9%; n = 18); ischemic stroke (IS), 0.75 (95% CI, 0.69-0.82; I² = 50.1%; n = 22); intracerebral hemorrhage (ICH), 1.21 (95% CI, 1.04-1.42; I² = 33.4%; n = 10); and subarachnoid hemorrhage (SAH), 0.98 (95% CI, 0.96-1.00; I² = 0%; n = 7). We found a linear inverse association between HDL-C level and risk of total stroke and SAH, a nonlinear inverse association for IS risk, but a linear positive association for ICH risk. The strength and the direction of the effect size estimate for total stroke, IS, ICH, and SAH remained stable for most subgroups. We found no publication bias with Begg's test and Egger's test for the association of HDL-C level with risk of total stroke, IS, and ICH.

CONCLUSION

A high HDL-C level is associated with reduced risk of total stroke and IS and an increased risk of ICH.

Dissecting lipid metabolism alterations in SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the COVID-19 pandemic that has infected over a hundred million people globally. There have been more than two million deaths recorded worldwide, with no end in sight until a widespread vaccination will be achieved. Current research has centred on different aspects of the virus interaction with cell surface receptors, but more needs to be done to further understand its mechanism of action in order to develop a targeted therapy and a method to control the spread of the virus. Lipids play a crucial role throughout the viral life cycle, and viruses are known to exploit lipid signalling and synthesis to affect host cell lipidome. Emerging studies using untargeted metabolomic and lipidomic approaches are providing new insight into the host response to COVID-19 infection. Indeed, metabolomic and lipidomic approaches have identified numerous circulating lipids that directly correlate to the severity of the disease, making lipid metabolism a potential therapeutic target. Circulating lipids play a key function in the pathogenesis of the virus and exert an inflammatory response. A better knowledge of lipid metabolism in the host-pathogen interaction will provide valuable insights into viral pathogenesis and to the development of novel therapeutic targets.

Synthetic high-density lipoproteins loaded with an antiplatelet drug for efficient inhibition of thrombosis in mice

Antiplatelet agents offer a desirable approach to thrombosis prevention through the reduction of platelet reactivity. However, major bleeding events greatly attenuate the clinical outcomes of most antithrombotic agents. Therefore, the development of safer and more effective strategies to prevent vascular occlusion and avoid bleeding is urgently needed. A reconstituted nanoparticle, synthetic high-density lipoprotein (sHDL), which mimics the native HDL, has been established as clinically safe and is easily manufactured on a large scale. In this study, we propose that the delivery of the antiplatelet drug ML355, a selective inhibitor of 12(S)-lipoxygenase (12-LOX), by sHDL will efficiently inhibit thrombosis by targeting ML355 to the intended site of action, improving the pharmaceutical profile and harnessing the innate antithrombotic efficacy of the sHDL carrier. Our data show that ML355-sHDL exhibits more potent inhibition of thrombus formation in both small arterioles and larger arteries in mice without impairing the normal hemostasis in vivo.

Targeting Lipid Rafts-A Potential Therapy for COVID-19

COVID-19 is a global pandemic currently in an acute phase of rapid expansion. While public health measures remain the most effective protection strategy at this stage, when the peak passes, it will leave in its wake important health problems. Historically, very few viruses have ever been eradicated. Instead, the virus may persist in communities causing recurrent local outbreaks of the acute infection as well as several chronic diseases that may arise from the presence of a “suppressed” virus or as a consequence of the initial exposure. An ideal solution would be an anti-viral medication that (i) targets multiple stages of the viral lifecycle, (ii) is insensitive to frequent changes of viral phenotype due to mutagenesis, (iii) has broad spectrum, (iv) is safe and (v) also targets co-morbidities of the infection. In this Perspective we discuss a therapeutic approach that owns these attributes, namely “lipid raft therapy.” Lipid raft therapy is an approach aimed at reducing the abundance and structural modifications of host lipid rafts or at targeted delivery of therapeutics to the rafts. Lipid rafts are the sites of the initial binding, activation, internalization and cell-to-cell transmission of SARS-CoV-2. They also are key regulators of immune and inflammatory responses, dysregulation of which is characteristic to COVID-19 infection. Lipid raft therapy was successful in targeting many viral infections and inflammatory disorders, and can potentially be highly effective for treatment of COVID-19.

Lipoprotein-based drug delivery

Lipoproteins (LPs) are circulating heterogeneous nanoparticles produced by the liver and intestines. LPs play a major role in the transport of dietary and endogenous lipids to target cells through cell membrane receptors or cell surface-bound lipoprotein lipase. The stability, biocompatibility, and selective transport of LPs make them promising delivery vehicles for various therapeutic and imaging agents. This review discusses isolation, manufacturing, and drug loading techniques used for LP-based drug delivery, as well as recent applications for diagnosis and treatment of cancer, atherosclerosis, and other life-threatening diseases.

Lipoproteins and lipids in cardiovascular disease: from mechanistic insights to therapeutic targeting

With cardiovascular disease being the leading cause of morbidity and mortality worldwide, effective and cost-efficient therapies to reduce cardiovascular risk are highly needed. Lipids and lipoprotein particles crucially contribute to atherosclerosis as underlying pathology of cardiovascular disease and influence inflammatory processes as well as function of leukocytes, vascular and cardiac cells, thereby impacting on vessels and heart. Statins form the first-line therapy with the aim to block cholesterol synthesis, but additional lipid-lowering drugs are sometimes needed to achieve low-density lipoprotein (LDL) cholesterol target values. Furthermore, beyond LDL cholesterol, also other lipid mediators contribute to cardiovascular risk. This review comprehensively discusses low- and high-density lipoprotein cholesterol, lipoprotein (a), triglycerides as well as fatty acids and derivatives in the context of cardiovascular disease, providing mechanistic insights into their role in pathological processes impacting on cardiovascular disease. Also, an overview of applied as well as emerging therapeutic strategies to reduce lipid-induced cardiovascular burden is provided.

Reconstituted High-density Lipoprotein Therapy Improves Survival in Mouse Models of Sepsis

BACKGROUND

High-density lipoproteins exert pleiotropic effects including antiinflammatory, antiapoptotic, and lipopolysaccharide-neutralizing properties. The authors assessed the effects of reconstituted high-density lipoproteins (CSL-111) intravenous injection in different models of sepsis.

METHODS

Ten-week-old C57BL/6 mice were subjected to sepsis by cecal ligation and puncture or intraperitoneal injection of Escherichia coli or Pseudomonas aeruginosa pneumonia. CSL-111 or saline solution was administrated 2 h after the sepsis. Primary outcome was survival. Secondary outcomes were plasma cell-free DNA and cytokine concentrations, histology, bacterial count, and biodistribution.

RESULTS

Compared with saline, CSL-111 improved survival in cecal ligation and puncture and intraperitoneal models (13 of 16 [81%] survival rate vs. 6 of 16 [38%] in the cecal ligation and puncture model; P = 0.011; 4 of 10 [40%] vs. 0 of 10 [0%] in the intraperitoneal model; P = 0.011). Cell-free DNA concentration was lower in CSL-111 relative to saline groups (68 [24 to 123] pg/ml vs. 351 [333 to 683] pg/ml; P < 0.001). Mice injected with CSL-111 presented a decreased bacterial count at 24 h after the cecal ligation and puncture model both in plasma (200 [28 to 2,302] vs. 2,500 [953 to 3,636] colony-forming unit/ml; P = 0.021) and in the liver (1,359 [360 to 1,648] vs. 1,808 [1,464 to 2,720] colony-forming unit/ml; P = 0.031). In the pneumonia model, fewer bacteria accumulated in liver and lung of the CSL-111 group. CSL-111-injected mice had also less lung inflammation versus saline mice (CD68+ to total cells ratio: saline, 0.24 [0.22 to 0.27]; CSL-111, 0.07 [0.01 to 0.09]; P < 0.01). In all models, no difference was found for cytokine concentration. Indium bacterial labeling underlined a potential hepatic bacterial clearance possibly promoted by high-density lipoprotein uptake.

CONCLUSIONS

CSL-111 infusion improved survival in different experimental mouse models of sepsis. It reduced inflammation in both plasma and organs and decreased bacterial count. These results emphasized the key role for high-density lipoproteins in endothelial and organ protection, but also in lipopolysaccharide/bacteria clearance. This suggests an opportunity to explore the therapeutic potential of high-density lipoproteins in septic conditions.

Genetic determinants of blood lipids and cerebral small vessel disease: role of high-density lipoprotein cholesterol

Blood lipids are causally involved in the pathogenesis of atherosclerosis, but their role in cerebral small vessel disease remains largely elusive. Here, we explored associations of genetic determinants of blood lipid levels, lipoprotein particle components, and targets for lipid-modifying drugs with small vessel disease phenotypes. We selected genetic instruments for blood levels of high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides, for cholesterol and triglycerides components of size-defined lipoprotein particles, and for lipid-modifying drug targets based on published genome-wide association studies (up to 617 303 individuals). Applying two-sample Mendelian randomization approaches we investigated associations with ischaemic and haemorrhagic manifestations of small vessel disease [small vessel stroke: 11 710 cases, 287 067 controls; white matter hyperintensities (WMH): 10 597 individuals; intracerebral haemorrhage: 1545 cases, 1481 controls]. We applied the inverse-variance weighted method and multivariable Mendelian randomization as our main analytical approaches. Genetic predisposition to higher HDL-C levels was associated with lower risk of small vessel stroke [odds ratio (OR) per standard deviation = 0.85, 95% confidence interval (CI) = 0.78-0.92] and lower WMH volume (β = -0.07, 95% CI = -0.12 to -0.02), which in multivariable Mendelian randomization remained stable after adjustments for LDL-C and triglycerides. In analyses of lipoprotein particle components by size, we found these effects to be specific for cholesterol concentration in medium-sized high-density lipoprotein, and not large or extra-large high-density lipoprotein particles. Association estimates for intracerebral haemorrhage were negatively correlated with those for small vessel stroke and WMH volume across all lipid traits and lipoprotein particle components. HDL-C raising genetic variants in the gene locus of the target of CETP inhibitors were associated with lower risk of small vessel stroke (OR: 0.82, 95% CI = 0.75-0.89) and lower WMH volume (β = -0.08, 95% CI = -0.13 to -0.02), but a higher risk of intracerebral haemorrhage (OR: 1.64, 95% CI = 1.26-2.13). Genetic predisposition to higher HDL-C, specifically to cholesterol in medium-sized high-density lipoprotein particles, is associated with both a lower risk of small vessel stroke and lower WMH volume. These analyses indicate that HDL-C raising strategies could be considered for the prevention of ischaemic small vessel disease but the net benefit of such an approach would need to be tested in a randomized controlled trial.

Lipid rafts as a therapeutic target

Lipid rafts regulate the initiation of cellular metabolic and signaling pathways by organizing the pathway components in ordered microdomains on the cell surface. Cellular responses regulated by lipid rafts range from physiological to pathological, and the success of a therapeutic approach targeting "pathological" lipid rafts depends on the ability of a remedial agent to recognize them and disrupt pathological lipid rafts without affecting normal raft-dependent cellular functions. In this article, concluding the Thematic Review Series on Biology of Lipid Rafts, we review current experimental therapies targeting pathological lipid rafts, including examples of inflammarafts and clusters of apoptotic signaling molecule-enriched rafts. The corrective approaches include regulation of cholesterol and sphingolipid metabolism and membrane trafficking by using HDL and its mimetics, LXR agonists, ABCA1 overexpression, and cyclodextrins, as well as a more targeted intervention with apoA-I binding protein. Among others, we highlight the design of antagonists that target inflammatory receptors only in their activated form of homo- or heterodimers, when receptor dimerization occurs in pathological lipid rafts. Other therapies aim to promote raft-dependent physiological functions, such as augmenting caveolae-dependent tissue repair. The overview of this highly dynamic field will provide readers with a view on the emerging concept of targeting lipid rafts as a therapeutic strategy.jlr;61/5/687/F1F1f1.

High-density lipoproteins during sepsis: from bench to bedside

High-density lipoproteins (HDLs) represent a family of particle characterized by the presence of apolipoprotein A-I (apoA-I) and by their ability to transport cholesterol from peripheral tissues back to the liver conferring them a cardioprotective function. HDLs also display pleiotropic properties including antioxidant, anti-apoptotic, anti-thrombotic, anti-inflammatory, or anti-infectious functions. Clinical data demonstrate that HDL cholesterol levels decrease rapidly during sepsis and that these low levels are correlated with morbi-mortality. Experimental studies emphasized notable structural and functional modifications of HDL particles in inflammatory states, including sepsis. Finally, HDL infusion in animal models of sepsis improved survival and provided a global endothelial protective effect. These clinical and experimental studies reinforce the potential of HDL therapy in human sepsis. In this review, we will detail the different effects of HDLs that may be relevant under inflammatory conditions and the lipoprotein changes during sepsis and we will discuss the potentiality of HDL therapy in sepsis.

Clearance of two organic nanoparticles from the brain via the paravascular pathway

The elaboration of nanotechnology offers valuable therapeutic options to overcome the blood-brain barrier and enable the treatment of brain diseases. However, to date, limit work has been done to reveal the fate of nanoparticles within the brain, which largely hinders their safe and effective applications. Here we demonstrated that the commonly-used organic nanoparticles reconstituted high density lipoprotein and poly(ethylene glycol)-b-poly(lactic acid) nanoparticles were cleared relatively fast from the brain (half-life <5 h). Notably, through various transgenic mice and pharmacological inhibition approaches, we revealed that the paravascular glymphatic pathway plays a key role (about 80%) in the brain clearance of the nanoparticles, and disclosed that microglia-mediated transportation is essential for facilitating nanoparticles elimination through the paravascular route. In addition, we witnessed a significant decline in the brain clearance of both of the nanoparticles in Alzheimer's model mice where the glymphatic system is impaired. These findings provide insightful data on the fate of nanoparticles in the brain, which would shed new light into the rational design and safe application of nanoparticles for brain drug delivery.

Effects of Virgin Olive Oil and Phenol-Enriched Virgin Olive Oils on Lipoprotein Atherogenicity

The atherogenicity of low-density lipoprotein (LDL) and triglyceride-rich lipoproteins (TRLs) may be more significant than LDL cholesterol levels. Clinical trials which have led to increased high-density lipoprotein (HDL) cholesterol have not always seen reductions in cardiovascular disease (CVD). Furthermore, genetic variants predisposing individuals to high HDL cholesterol are not associated with a lower risk of suffering a coronary event, and therefore HDL functionality is considered to be the most relevant aspect. Virgin olive oil (VOO) is thought to play a protective role against CVD. This review describes the effects of VOO and phenol-enriched VOOs on lipoprotein atherogenicity and HDL atheroprotective properties. The studies have demonstrated a decrease in LDL atherogenicity and an increase in the HDL-mediated macrophage cholesterol efflux capacity, HDL antioxidant activity, and HDL anti-inflammatory characteristics after various VOO interventions. Moreover, the expression of cholesterol efflux-related genes was enhanced after exposure to phenol-enriched VOOs in both post-prandial and sustained trials. Improvements in HDL antioxidant properties were also observed after VOO and phenol-enriched VOO interventions. Furthermore, some studies have demonstrated improved characteristics of TRL atherogenicity under postprandial conditions after VOO intake. Large-scale, long-term randomized clinical trials, and Mendelian analyses which assess the lipoprotein state and properties, are required to confirm these results.

Influence of Cardiometabolic Risk Factors on Platelet Function

Platelets are key players in the thrombotic processes. The alterations of platelet function due to the occurrence of metabolic disorders contribute to an increased trend to thrombus formation and arterial occlusion, thus playing a major role in the increased risk of atherothrombotic events in patients with cardiometabolic risk factors. Several lines of evidence strongly correlate metabolic disorders such as obesity, a classical condition of insulin resistance, dyslipidemia, and impaired glucose homeostasis with cardiovascular diseases. The presence of these clinical features together with hypertension and disturbed microhemorrheology are responsible for the prothrombotic tendency due, at least partially, to platelet hyperaggregability and hyperactivation. A number of clinical platelet markers are elevated in obese and type 2 diabetes (T2DM) patients, including the mean platelet volume, circulating levels of platelet microparticles, oxidation products, platelet-derived soluble P-selectin and CD40L, thus contributing to an intersection between obesity, inflammation, and thrombosis. In subjects with insulin resistance and T2DM some defects depend on a reduced sensitivity to mediators—such as nitric oxide and prostacyclin—playing a physiological role in the control of platelet aggregability. Furthermore, other alterations occur only in relation to hyperglycemia. In this review, the main cardiometabolic risk factors, all components of metabolic syndrome involved in the prothrombotic tendency, will be taken into account considering some of the mechanisms involved in the alterations of platelet function resulting in platelet hyperactivation.

HDL therapy today: from atherosclerosis, to stent compatibility to heart failure

Epidemiologically, high-density lipoprotein (HDL) cholesterol levels have been inversely associated to cardiovascular (CV) events, although a Mendelian Randomisation Study had failed to establish a clear causal role. Numerous atheroprotective mechanisms have been attributed to HDL, the main being the ability to promote cholesterol efflux from arterial walls; anti-inflammatory effects related to HDL ligands such as S1P (sphingosine-1-phosphate), resolvins and others have been recently identified. Experimental studies and early clinical investigations have indicated the potential of HDL to slow progression or induce regression of atherosclerosis. More recently, the availability of different HDL formulations, with different phospholipid moieties, has allowed to test other indications for HDL therapy. Positive reports have come from studies on coronary stent biocompatibility, where the use of HDL from different sources reduced arterial cell proliferation and thrombogenicity. The observation that low HDL-C levels may be associated with an enhanced risk of heart failure (HF) has also suggested that HDL therapy may be applied to this condition. HDL infusions or apoA-I gene transfer were able to reverse heart abnormalities, reduce diastolic resistance and improve cardiac metabolism. HDL therapy may be effective not only in atherosclerosis, but also in other conditions, of relevant impact on human health.Key messagesHigh-density lipoproteins have as a major activity that of removing excess cholesterol from tissues (particularly arteries).Knowledge on the activity of high-density lipoproteins on health have however significantly widened.HDL-therapy may help to improve stent biocompatibility and to reduce peripheral arterial resistance in heart failure.

Anti-Inflammatory Effects of HDL (High-Density Lipoprotein) in Macrophages Predominate Over Proinflammatory Effects in Atherosclerotic Plaques

OBJECTIVE

HDL (high-density lipoprotein) infusion reduces atherosclerosis in animal models and is being evaluated as a treatment in humans. Studies have shown either anti- or proinflammatory effects of HDL in macrophages, and there is no consensus on the underlying mechanisms. Here, we interrogate the effects of HDL on inflammatory gene expression in macrophages. Approach and Results: We cultured bone marrow-derived macrophages, treated them with reconstituted HDL or HDL isolated from APOA1^Tg;Ldlr^-/- mice, and challenged them with lipopolysaccharide. Transcriptional profiling showed that HDL exerts a broad anti-inflammatory effect on lipopolysaccharide-induced genes and proinflammatory effect in a subset of genes enriched for chemokines. Cholesterol removal by POPC (1-palmitoyl-2-oleoyl-glycero-3-phosphocholine) liposomes or β-methylcyclodextrin mimicked both pro- and anti-inflammatory effects of HDL, whereas cholesterol loading by POPC/cholesterol-liposomes or acetylated LDL (low-density lipoprotein) before HDL attenuated these effects, indicating that these responses are mediated by cholesterol efflux. While early anti-inflammatory effects reflect reduced TLR (Toll-like receptor) 4 levels, late anti-inflammatory effects are due to reduced IFN (interferon) receptor signaling. Proinflammatory effects occur late and represent a modified endoplasmic reticulum stress response, mediated by IRE1a (inositol-requiring enzyme 1a)/ASK1 (apoptosis signal-regulating kinase 1)/p38 MAPK (p38 mitogen-activated protein kinase) signaling, that occurs under conditions of extreme cholesterol depletion. To investigate the effects of HDL on inflammatory gene expression in myeloid cells in atherosclerotic lesions, we injected reconstituted HDL into Apoe^-/- or Ldlr^-/- mice fed a Western-type diet. Reconstituted HDL infusions produced anti-inflammatory effects in lesion macrophages without any evidence of proinflammatory effects.

CONCLUSIONS

Reconstituted HDL infusions in hypercholesterolemic atherosclerotic mice produced anti-inflammatory effects in lesion macrophages suggesting a beneficial therapeutic effect of HDL in vivo.

High-Density Lipoproteins and Apolipoprotein A-I Improve Stent Biocompatibility

Revascularization because of coronary artery disease is commonly achieved by percutaneous coronary intervention with stent deployment. Refinement in interventional techniques, major improvements in stent design (particularly drug-eluting stents), and adjunctive pharmacotherapy with dual antiplatelet regimens have led to marked reductions in the overall rates of stent failure. However, even with the advancements made in the latest generation of drug-eluting stents, unresolved biological problems persist including delayed re-endothelialization and neoatherosclerosis, which can promote late expansion of the neointima and late stent thrombosis. Novel strategies are still needed beyond what is currently available to specifically address the pathobiological processes that underpin the residual risk for adverse clinical events. This review focuses on the emerging evidence that HDL (high-density lipoproteins) and its main apo (apolipoprotein), apoA-I, exhibit multiple vascular biological functions that are associated with an improvement in stent biocompatibility. HDL/apoA-I have recently been shown to inhibit in-stent restenosis in animal models of stenting and suppress smooth muscle cell proliferation in in vitro studies. Reconstituted HDL also promotes endothelial cell migration, endothelial progenitor cell mobilization, and re-endothelialization. Furthermore, reconstituted HDL decreases platelet activation and HDL cholesterol is inversely associated with the risk of thrombosis. Finally, reconstituted HDL/apoA-I suppresses key inflammatory mechanisms that initiate in-stent neoatherosclerosis and can efflux cholesterol from plaque macrophages, an important function of HDLs that prevents plaque progression. These unique multifunctional effects of HDL/apoA-I suggest that, if translated appropriately, have the potential to improve stent biocompatibility. This may provide an alternate and more efficacious therapeutic pathway for the translation of HDL.

HDL Cholesterol as a Marker of Disease Severity and Prognosis in Patients with Pulmonary Arterial Hypertension

The impact of high-density lipoprotein (HDL) cholesterol on the development of atherosclerosis and diseases of systemic circulation has been well documented both in experimental and registry studies. Recent discoveries in pulmonary arterial hypertension (PAH) revealed a significant impact of HDL on pulmonary artery vasoreactivity and patients' prognosis. The vasoprotective activity of HDL primarily involves vascular endothelium that also plays a central role in pulmonary arterial hypertension (PAH) pathobiology. However, the exact mechanism in which this lipoprotein fraction exerts its effect in pulmonary circulation is still under investigation. This paper reviews potential vasoprotective mechanisms of HDL in pulmonary circulation and presents current clinical reports on the role of HDL in PAH patients.

Relationship Between HDL Functional Characteristics and Cardiovascular Health and Potential Impact of Dietary Patterns: A Narrative Review

Cardiovascular disease is a leading cause of death around the world. Overall diet quality and dietary behaviors are core contributors to metabolic health. While therapeutic targets have traditionally focused on levels of lipoprotein cholesterol when evaluating cardiovascular risk, current perspectives on high-density lipoprotein (HDL) have shifted to evaluating the functionality of this lipoprotein particle. Effects of diet on cardiovascular health are mediated through multiple pathways, but the impact on HDL composition and function deserves greater attention. Potential areas of investigation involve changes in particle characteristics, distribution, microRNA cargo, and other functional changes such as improvements to cholesterol efflux capacity. Various dietary patterns like the Mediterranean diet and Dietary Approaches to Stop Hypertension (DASH) diet have beneficial effects on cardiovascular health and may prevent cardiovascular events. These healthful dietary patterns tend to be rich in plant-based foods, with cardiovascular benefits likely resulting from synergistic effects of the individual dietary components. The purpose of this review is to summarize current perspectives on selected functions of HDL particles and how various dietary patterns affect cardiovascular health biomarkers, with a focus on HDL functionality.

Increased platelet reactivity in dyslipidemic patients with coronary artery disease on dual anti-platelet therapy

INTRODUCTION

The optimal duration of dual anti-platelet therapy (DAPT) following percutaneous coronary intervention (PCI) is still a matter of debate. Biomarkers may help to identify patients who will benefit from extended DAPT. The aim of the study was to test the interaction between lipid parameters and platelet function in patients with coronary artery disease (CAD) on DAPT.

MATERIAL AND METHODS

Overall, 58 patients on DAPT were prospectively included following PCI in stable CAD. Platelet markers, i.e. mean platelet volume (MPV), platelet distribution width (PDW), fraction of reticulated thrombocytes (RT) and ADP-induced multiple electrode aggregometry (MEA), as well as serum lipids, i.e. high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglycerides (TG) and remnant cholesterol (RC), were assessed after intake of a maintenance dose of ASA and P2Y12 inhibitor.

RESULTS

A significant inverse correlation was found for HDL-C levels and markers of platelet activation: MPV (r = -0.351, p = 0.009), PDW (r = -0.391, p = 0.003), fraction of RT (r = -0.402, p = 0.003) and ADP-induced MEA (r = -0.345, p = 0.011). Only a weak or no association was found between other lipid parameters and platelet markers. After multivariable adjustment, HDL-C levels served as a strong and significant predictor of MPV (95% CI: -0.039 to -0.009; p = 0.002), PDW (95% CI: -0.094 to -0.034; p < 0.0001), RT (95% CI: -0.107 to -0.031; p = 0.001) and MEA (95% CI: -0.540 to -0.170; p < 0.0001), while TG, LDL-C, RC and TC were not significantly associated with platelet function.

CONCLUSIONS

Within lipid parameters, only HDL-C levels are strongly associated with markers of platelet activation in CAD patients on DAPT. Accordingly, detection of dyslipidemia might indicate the need for prolongation of DAPT.

Cholesterol transport system: An integrated cholesterol transport model involved in atherosclerosis

Atherosclerosis, the pathological basis of most cardiovascular disease (CVD), is closely associated with cholesterol accumulation in the arterial intima. Excessive cholesterol is removed by the reverse cholesterol transport (RCT) pathway, representing a major antiatherogenic mechanism. In addition to the RCT, other pathways are required for maintaining the whole-body cholesterol homeostasis. Thus, we propose a working model of integrated cholesterol transport, termed the cholesterol transport system (CTS), to describe body cholesterol metabolism. The novel model not only involves the classical view of RCT but also contains other steps, such as cholesterol absorption in the small intestine, low-density lipoprotein uptake by the liver, and transintestinal cholesterol excretion. Extensive studies have shown that dysfunctional CTS is one of the major causes for hypercholesterolemia and atherosclerosis. Currently, several drugs are available to improve the CTS efficiently. There are also several therapeutic approaches that have entered into clinical trials and shown considerable promise for decreasing the risk of CVD. In recent years, a variety of novel findings reveal the molecular mechanisms for the CTS and its role in the development of atherosclerosis, thereby providing novel insights into the understanding of whole-body cholesterol transport and metabolism. In this review, we summarize the latest advances in this area with an emphasis on the therapeutic potential of targeting the CTS in CVD patients.

Current Therapies Focused on High-Density Lipoproteins Associated with Cardiovascular Disease

High-density lipoproteins (HDL) comprise a heterogeneous family of lipoprotein particles divided into subclasses that are determined by density, size and surface charge as well as protein composition. Epidemiological studies have suggested an inverse correlation between High-density lipoprotein-cholesterol (HDL-C) levels and the risk of cardiovascular diseases and atherosclerosis. HDLs promote reverse cholesterol transport (RCT) and have several atheroprotective functions such as anti-inflammation, anti-thrombosis, and anti-oxidation. HDLs are considered to be atheroprotective because they are associated in serum with paraoxonases (PONs) which protect HDL from oxidation. Polyphenol consumption reduces the risk of chronic diseases in humans. Polyphenols increase the binding of HDL to PON1, increasing the catalytic activity of PON1. This review summarizes the evidence currently available regarding pharmacological and alternative treatments aimed at improving the functionality of HDL-C. Information on the effectiveness of the treatments has contributed to the understanding of the molecular mechanisms that regulate plasma levels of HDL-C, thereby promoting the development of more effective treatment of cardiovascular diseases. For that purpose, Scopus and Medline databases were searched to identify the publications investigating the impact of current therapies focused on high-density lipoproteins.

The Main Determinants of Diabetes Mellitus Vascular Complications: Endothelial Dysfunction and Platelet Hyperaggregation

Diabetes mellitus is a common disease that affects 3–5% of the general population in Italy. In some countries of northern Europe or in North America, it can even affect 6–8% of the population. Of great concern is that the number of cases of diabetes is constantly increasing, probably due to the increase in obesity and the sedentary nature of the population. According to the World Health Organization, in the year 2030 there will be 360 million people with diabetes, compared to 170 million in 2000. This has important repercussions on the lives of patients and their families, and on health systems that offer assistance to patients. In this review, we try to describe in an organized way the pathophysiological continuity between diabetes mellitus, endothelial dysfunction, and platelet hyperaggregation, highlighting the main molecular mechanisms involved and the interconnections.

Evaluation of potential antiplatelet effects of CSL112 (Apolipoprotein A-I [Human]) in patients with atherosclerosis: results from a phase 2a study

CSL112 (Apolipoprotein A-I [Human]), an infusible, plasma-derived apolipoprotein A-I, is being developed to reduce cardiovascular events following acute myocardial infarction (AMI). A predecessor compound (CSL111) demonstrated a potential antiplatelet effect. A phase 2a multicentre, randomised, single-ascending dose study in patients with stable atherosclerotic disease receiving dual antiplatelet therapy (DAPT) assessed the potential additive effects of CSL112 administration on platelet function and increase bleeding risk in the subacute period after AMI. Patients (n = 44) on aspirin (75–325 mg/day) and either clopidogrel (75 mg/day, n = 37) or prasugrel (10 mg/day, n = 7) for > 30 days alongside standard-of-care therapy were randomised to a single dose of placebo or CSL112: 1.7, 3.4, or 6.8 g. Light transmission aggregometry was used to assess platelet aggregation in response to 2 mM arachidonic acid, 5 and 20 µM adenosine diphosphate, and 4 µg/mL collagen, pre-dose (baseline) and up to 48 h post-dosing. Compared to placebo, CSL112 had no clinically meaningful time- or dose-dependent effects on maximum platelet aggregation in response to any agonist, by either dose or renal function subgroup (p > 0.05). Coagulation parameters showed little variation over time or between treatment groups (p > 0.05). CSL112, when co-administered with standard DAPT, did not significantly influence platelet aggregation in response to agonists and is, therefore, not expected to significantly increase bleeding risk when administered with antiplatelet therapies.

Apolipoprotein A-IV binds αIIbβ3 integrin and inhibits thrombosis

Platelet αIIbβ3 integrin and its ligands are essential for thrombosis and hemostasis, and play key roles in myocardial infarction and stroke. Here we show that apolipoprotein A-IV (apoA-IV) can be isolated from human blood plasma using platelet β3 integrin-coated beads. Binding of apoA-IV to platelets requires activation of αIIbβ3 integrin, and the direct apoA-IV-αIIbβ3 interaction can be detected using a single-molecule Biomembrane Force Probe. We identify that aspartic acids 5 and 13 at the N-terminus of apoA-IV are required for binding to αIIbβ3 integrin, which is additionally modulated by apoA-IV C-terminus via intra-molecular interactions. ApoA-IV inhibits platelet aggregation and postprandial platelet hyperactivity. Human apoA-IV plasma levels show a circadian rhythm that negatively correlates with platelet aggregation and cardiovascular events. Thus, we identify apoA-IV as a novel ligand of αIIbβ3 integrin and an endogenous inhibitor of thrombosis, establishing a link between lipoprotein metabolism and cardiovascular diseases.

Activation of integrin αIIbβ3 at the surface of platelets is required for their aggregation and for thrombus formation. Here Xu et al. identify apolipoprotein A-IV as a novel ligand for platelet αIIbβ3 integrin, and find it inhibits platelet aggregation and thrombosis.

Endothelial dysfunction and platelet hyperactivity in type 2 diabetes mellitus: molecular insights and therapeutic strategies

The incidence and prevalence of diabetes mellitus is rapidly increasing worldwide at an alarming rate. Type 2 diabetes mellitus (T2DM) is the most prevalent form of diabetes, accounting for approximately 90-95% of the total diabetes cases worldwide. Besides affecting the ability of body to use glucose, it is associated with micro-vascular and macro-vascular complications. Augmented atherosclerosis is documented to be the key factor leading to vascular complications in T2DM patients. The metabolic milieu of T2DM, including insulin resistance, hyperglycemia and release of excess free fatty acids, along with other metabolic abnormalities affects vascular wall by a series of events including endothelial dysfunction, platelet hyperactivity, oxidative stress and low-grade inflammation. Activation of these events further enhances vasoconstriction and promotes thrombus formation, ultimately resulting in the development of atherosclerosis. All these evidences are supported by the clinical trials reporting the importance of endothelial dysfunction and platelet hyperactivity in the pathogenesis of atherosclerotic vascular complications. In this review, an attempt has been made to comprehensively compile updated information available in context of endothelial and platelet dysfunction in T2DM.