Infusion of Reconstituted High-Density Lipoprotein, CSL112, in Patients With Atherosclerosis: Safety and Pharmacokinetic Results From a Phase 2a Randomized Clinical Trial

Enhancing Wound Healing and Anti-Inflammatory Effects by Combination of CIGB-258 and Apolipoprotein A-I against Carboxymethyllysine Toxicity in Zebrafish: Insights into Structural Stabilization and Antioxidant Properties

CIGB-258 is known to exert anti-inflammatory activity via structural stabilization of apolipoprotein A-I (apoA-I) and functional enhancement of high-density lipoproteins (HDL) against acute toxicity of carboxymethyllysine (CML). The co-presence of CIGB-258 in reconstituted HDL (rHDL) formed larger rHDL particles and enhanced anti-inflammatory activity in a dose-dependent manner of apoA-I:CIGB-258, 1:0, 1:0.1, 1:0.5, and 1:1 of molar ratio, in the synthesis of the rHDL. However, no study has evaluated the enhancement of HDL functionality by the co-presence of lipid-free apoA-I and CIGB-258. The present study was therefore designed to compare the structural stabilization and functional improvement of HDL in the presence of lipid-free apoA-I and CIGB-258 in molar ratios of 1:0, 1:0.1, 1:0.5, and 1:1 within both HDL2 and HDL3. As the concentration of CIGB-258 increased, it effectively inhibited the cupric-ion-induced oxidation of HDL, thereby safeguarding apoA-I from proteolytic degradation. Additionally, the wound-healing activity of zebrafish was significantly (p < 0.01) enhanced by the co-addition of apoA-I:CIGB-258 (1:1) up to 1.6-fold higher than apoA-I alone (1:0) under the presence of CML. ApoA-I:CIGB-258 (1:1) treatment exhibited the lowest apoptosis and production of reactive oxygen species against CML-induced damage in the wound site. Also, an increase in wounded tissue granulation and epidermis thickness was observed with increasing concentration of CIGB-258 during 48 h post-treatment via the healing process. Intraperitoneal injection of apoA-I:CIGB-258 mixture remarkably ameliorated the acute paralysis and restored zebrafish swimming ability impaired by the acute toxicity of CML. The increase of CIGB-258 content, especially co-injection of apoA-I:CIGB-258 (1:1), leads to a significant 2.3-fold (p < 0.001) and 4.1-fold (p < 0.001) higher zebrafish survivability and recovery of swimming ability, respectively, than those of CML-control. In the apoA-I:CIGB-258 (1:1) group, neutrophil infiltration and interleukin (IL)-6 production was lowest in the hepatic tissue with the least cellular damage and apoptosis. Additionally, the group treated with apoA-I:CIGB-258 (1:1) demonstrated the lowest plasma levels of total cholesterol (TC) and triglycerides (TG), along with minimal damage to the kidney, ovary, and testicular cells. Conclusively, co-treatment of CIGB-258 with apoA-I effectively mitigated acute inflammation in zebrafish, safeguarded vital organs, structurally stabilized apoA-I, and enhanced HDL functionality.

Can CSL-112 revolutionize atherosclerosis treatment? A critical look at the evidence

CSL-112, a recombinant human apolipoprotein A-I, holds promise for treating atherosclerotic disease by promoting reverse cholesterol transport. This review evaluates the current evidence on CSL-112's impact on atherosclerotic disease. A search identified studies investigating the effect of CSL-112 on apolipoprotein A-I levels, cholesterol efflux capacity, clinical outcomes, safety profile, pharmacokinetics, pharmacodynamics, and subgroup analysis in patients with atherosclerotic disease. All nine studies consistently demonstrated a dose-dependent increase in apolipoprotein A-I levels following CSL-112 administration. Most studies also reported a corresponding rise in cholesterol efflux capacity. However, the AEGIS-II trial, the largest study to date, did not show a statistically significant reduction in major adverse cardiovascular events in patients with acute myocardial infarction treated with CSL-112 compared to placebo. While some smaller studies suggested potential benefits, particularly in stable atherosclerotic disease, their limitations in size and duration necessitate further investigation. CSL-112 appeared to be generally well-tolerated, with mostly mild or moderate adverse events reported. However, the AEGIS-II trial identified a higher incidence of hypersensitivity reactions in the CSL-112 group, requiring further exploration. CSL-112 demonstrates promise in raising apolipoprotein A-I levels and enhancing cholesterol efflux capacity, potentially promoting reverse cholesterol transport. However, its clinical efficacy for atherosclerotic disease remains unclear. Larger, well-designed trials with longer follow-up periods are necessary to definitively establish its clinical benefit and safety profile before widespread clinical use can be considered. Future research should also explore deeper into the pharmacokinetic and pharmacodynamic profile of CSL-112 and explore its efficacy and safety in different patient subgroups.

HDL abnormalities in type 2 diabetes: Clinical implications

Atherosclerotic cardiovascular disease (ASCVD) represents the primary cause of mortality among patients with Type 2 Diabetes Mellitus (T2DM). In this population, High-Density Lipoprotein (HDL) particles exhibit abnormalities in number, composition, and function, culminating in diminished anti-atherosclerotic capabilities despite normal HDL cholesterol (HDL-C) concentrations. Hyperglycemic conditions contribute to these alterations in HDL kinetics, composition, and function, causing T2DM patients' HDL particles to exhibit decreased concentrations of diverse lipid species and proteins. Treatment of hyperglycemia has the potential to correct abnormal HDL particle attributes in T2DM; however, pharmacological interventions, including metformin and thiazolidinediones, yield inconsistent outcomes with respect to HDL-C concentrations and functionality. Despite numerous attempts with diverse drugs, pharmacologically augmenting HDL-C levels has not resulted in clinical benefits in mitigating ASCVD risk. In contrast, reducing Low Density Lipoprotein cholesterol (LDL-C) via statins and ezetimibe has demonstrated significant efficacy in curtailing CVD risk among T2DM individuals. Promising results have been observed in animal models and early-phase trials utilizing recombinant HDL and Lecitin Cholesterol Acyl Transferase (LCAT) -enhancing agents, but the evaluation of their efficacy and safety in large-scale clinical trials is ongoing. While aberrant HDL metabolism constitutes a prevalent aspect of dyslipidemia in T2DM, HDL cholesterol concentrations and composition no longer offer valuable insights for informing therapeutic decisions. Nevertheless, HDL metabolism remains a critical research area in T2DM, necessitating further investigation to elucidate the role of HDL particles in the development of diabetes-associated complications.

Lipid exchange of apolipoprotein A-I amyloidogenic variants in reconstituted high-density lipoprotein with artificial membranes

High-density lipoproteins (HDLs) are responsible for removing cholesterol from arterial walls, through a process known as reverse cholesterol transport. The main protein in HDL, apolipoprotein A-I (ApoA-I), is essential to this process, and changes in its sequence significantly alter HDL structure and functions. ApoA-I amyloidogenic variants, associated with a particular hereditary degenerative disease, are particularly effective at facilitating cholesterol removal, thus protecting carriers from cardiovascular disease. Thus, it is conceivable that reconstituted HDL (rHDL) formulations containing ApoA-I proteins with functional/structural features similar to those of amyloidogenic variants hold potential as a promising therapeutic approach. Here we explored the effect of protein cargo and lipid composition on the function of rHDL containing one of the ApoA-I amyloidogenic variants G26R or L174S by Fourier transformed infrared spectroscopy and neutron reflectometry. Moreover, small-angle x-ray scattering uncovered the structural and functional differences between rHDL particles, which could help to comprehend higher cholesterol efflux activity and apparent lower phospholipid (PL) affinity. Our findings indicate distinct trends in lipid exchange (removal vs. deposition) capacities of various rHDL particles, with the rHDL containing the ApoA-I amyloidogenic variants showing a markedly lower ability to remove lipids from artificial membranes compared to the rHDL containing the native protein. This effect strongly depends on the level of PL unsaturation and on the particles' ultrastructure. The study highlights the importance of the protein cargo, along with lipid composition, in shaping rHDL structure, contributing to our understanding of lipid-protein interactions and their behavior.

Nanomedicine for Diagnosis and Treatment of Atherosclerosis

With the changing disease spectrum, atherosclerosis has become increasingly prevalent worldwide and the associated diseases have emerged as the leading cause of death. Due to their fascinating physical, chemical, and biological characteristics, nanomaterials are regarded as a promising tool to tackle enormous challenges in medicine. The emerging discipline of nanomedicine has filled a huge application gap in the atherosclerotic field, ushering a new generation of diagnosis and treatment strategies. Herein, based on the essential pathogenic contributors of atherogenesis, as well as the distinct composition/structural characteristics, synthesis strategies, and surface design of nanoplatforms, the three major application branches (nanodiagnosis, nanotherapy, and nanotheranostic) of nanomedicine in atherosclerosis are elaborated. Then, state-of-art studies containing a sequence of representative and significant achievements are summarized in detail with an emphasis on the intrinsic interaction/relationship between nanomedicines and atherosclerosis. Particularly, attention is paid to the biosafety of nanomedicines, which aims to pave the way for future clinical translation of this burgeoning field. Finally, this comprehensive review is concluded by proposing unresolved key scientific issues and sharing the vision and expectation for the future, fully elucidating the closed loop from atherogenesis to the application paradigm of nanomedicines for advancing the early achievement of clinical applications.

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.

Isolation of recombinant apolipoprotein E4 N-terminal domain by foam fractionation

Apolipoprotein (apo) E functions in lipoprotein metabolism as a low density lipoprotein receptor ligand. ApoE is comprised of two structural domains, a 22 kDa N-terminal (NT) domain that adopts a helix bundle conformation and a 10 kDa C-terminal domain with strong lipid binding affinity. The NT domain is capable of transforming aqueous phospholipid dispersions into discoidal reconstituted high density lipoprotein (rHDL) particles. Given the utility of apoE-NT as a structural component of rHDL, expression studies were conducted. A plasmid construct encoding a pelB leader sequence fused to the N-terminus of human apoE4 (residues 1-183) was transformed into Escherichia coli. Upon expression, the fusion protein is directed to the periplasmic space where leader peptidase cleaves the pelB sequence, generating mature apoE4-NT. In shaker flask expression cultures, apoE4-NT escapes the bacteria and accumulates in the medium. In a bioreactor setting, however, apoE4-NT was found to combine with gas and liquid components in the culture medium to generate large quantities of foam. When this foam was collected in an external vessel and collapsed into a liquid foamate, analysis revealed that apoE4-NT was the sole major protein present. The product protein was further isolated by heparin affinity chromatography (60-80 mg/liter bacterial culture), shown to be active in rHDL formulation, and documented to serve as an acceptor of effluxed cellular cholesterol. Thus, foam fractionation provides a streamlined process to produce recombinant apoE4-NT for biotechnology applications.

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.

A method for detection of anti-drug antibodies to a biotherapeutic (CSL112) with endogenous counterpart (apolipoprotein A-I) using a novel sample pre-treatment electrochemiluminescence assay

BACKGROUND

There are numerous challenges encountered during clinical testing for an immunogenic response to a plasma-derived therapeutic. Distinguishing between antibodies that recognize endogenous versus therapeutic protein can be particularly difficult. This study focused on CSL112 (human plasma-derived apolipoprotein A-I; apoA-I), which is in clinical development for reducing the risk of recurrent major adverse cardiovascular events following acute myocardial infarction.

AIM

To develop and validate a high-throughput, highly sensitive and specific assay to detect antibodies to CSL112 that can be used for immunogenicity assessment in large clinical studies.

RESULTS

We developed a clinical anti-drug antibody (ADA) assay utilizing an immunoglobulin purification step that improved specificity and drug tolerance, demonstrating that measurement of pre-existing or treatment emergent ADAs was highly dependent on assay format. The Sample Pre-treatment Electrochemiluminescence (ECL; SPECL) assay incorporates a protein A extraction of serum samples before a bridging assay is performed on an ECL platform. The assay is qualitative, sensitive (lower limit of quantification <39 ng/mL) and has a drug tolerance of 0.5 mg/mL in line with U.S. Food and Drug Administration requirements for clinical immunogenicity assays for therapeutic proteins. Importantly, the SPECL assay demonstrated the absence of antibodies to both apoA-I and CSL112 both prior to drug exposure and after repeated dosing across multiple trials (n = 970 subjects).

CONCLUSION

The SPECL method has been validated and applied to support the CSL112 preclinical and clinical development program and has broader application to similar protein therapeutics. Attributes of the methodology include high drug tolerance, high sensitivity, selectivity, and precision. This format is amenable to automation providing the high throughput and reduced variability required to support large scale clinical studies that span extended time periods.

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).

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.

High-density lipoprotein revisited: biological functions and clinical relevance

Previous interest in high-density lipoproteins (HDLs) focused on their possible protective role in atherosclerotic cardiovascular disease (ASCVD). Evidence from genetic studies and randomized trials, however, questioned that the inverse association of HDL-cholesterol (HDL-C) is causal. This review aims to provide an update on the role of HDL in health and disease, also beyond ASCVD. Through evolution from invertebrates, HDLs are the principal lipoproteins, while apolipoprotein B-containing lipoproteins first developed in vertebrates. HDLs transport cholesterol and other lipids between different cells like a reusable ferry, but serve many other functions including communication with cells and the inactivation of biohazards like bacterial lipopolysaccharides. These functions are exerted by entire HDL particles or distinct proteins or lipids carried by HDL rather than by its cholesterol cargo measured as HDL-C. Neither does HDL-C measurement reflect the efficiency of reverse cholesterol transport. Recent studies indicate that functional measures of HDL, notably cholesterol efflux capacity, numbers of HDL particles, or distinct HDL proteins are better predictors of ASCVD events than HDL-C. Low HDL-C levels are related observationally, but also genetically, to increased risks of infectious diseases, death during sepsis, diabetes mellitus, and chronic kidney disease. Additional, but only observational, data indicate associations of low HDL-C with various autoimmune diseases, and cancers, as well as all-cause mortality. Conversely, extremely high HDL-C levels are associated with an increased risk of age-related macular degeneration (also genetically), infectious disease, and all-cause mortality. HDL encompasses dynamic multimolecular and multifunctional lipoproteins that likely emerged during evolution to serve several physiological roles and prevent or heal pathologies beyond ASCVD. For any clinical exploitation of HDL, the indirect marker HDL-C must be replaced by direct biomarkers reflecting the causal role of HDL in the respective disease.

Effect of CSL112 (apolipoprotein A-I [human]) on cholesterol efflux capacity in Japanese subjects: Findings from a phase I study and a cross-study comparison

CSL112 (apolipoprotein A-I [apoA-I, human]) is a novel drug in development to reduce the risk of recurrent cardiovascular events following acute myocardial infarction by increasing cholesterol efflux capacity (CEC). This phase I study aimed to compare the pharmacokinetics (PKs), pharmacodynamics (PDs), and safety of CSL112 in Japanese and White subjects. A total of 34 Japanese subjects were randomized to receive a single infusion of CSL112 (2, 4, or 6 g) or placebo and 18 White subjects were randomized to receive a single dose of 6 g CSL112 or placebo, followed by PK/PD assessment and adverse events monitoring. In addition, PK/PD parameters were compared across the CSL112 clinical development program. Plasma exposure of apoA-I increased in a dose-dependent but nonlinear manner in Japanese subjects receiving a single dose of CSL112. Mean baseline-corrected area under the curve from 0 to 72 h (AUC_0-72 ) increased from 840 to 6490 mg h/dl, in the 2 and 6 g cohorts, respectively, followed by dose-dependent increase of CEC. The plasma PK profile of apoA-I and increases in total and ATP binding cassette transporter A1 dependent CEC were comparable in Japanese and White subjects. The geometric mean ratio (Japanese:White) for plasma apoA-I AUC_0-72 and maximum plasma concentration (C_max ) was 1.08 and 0.945, respectively. Cross-study comparison analysis demonstrated similar CSL112 exposure and CEC enhancement in Japanese and non-Japanese subjects (including patients with cardiovascular disease) and further confirmed consistent PKs/PDs of CSL112. This study suggests CSL112 acutely enhances CEC and is well-tolerated with no differences between Japanese and White subjects.

Effect of Lipid Composition on the Atheroprotective Properties of HDL-Mimicking Micelles

Atherosclerosis progression is driven by an imbalance of cholesterol and unresolved local inflammation in the arteries. The administration of recombinant apolipoprotein A-I (ApoA-I)-based high-density lipoprotein (HDL) nanoparticles has been used to reduce the size of atheroma and rescue inflammatory response in clinical studies. Because of the difficulty in producing large quantities of recombinant ApoA-I, here, we describe the preparation of phospholipid-based, ApoA-I-free micelles that structurally and functionally resemble HDL nanoparticles. Micelles were prepared using various phosphatidylcholine (PC) lipids combined with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[azido(polyethylene glycol)-2000] (DSPE-PEG2k) to form nanoparticles of 15-30 nm in diameter. The impacts of PC composition and PEGylation on the anti-inflammatory activity, cholesterol efflux capacity, and cholesterol crystal dissolution potential of micelles were investigated in vitro. The effects of micelle composition on pharmacokinetics and cholesterol mobilization ability were evaluated in vivo in Sprague Dawley rats. The study shows that the composition of HDL-mimicking micelles impacts their overall atheroprotective properties and supports further investigation of micelles as a therapeutic for the treatment of atherosclerosis.

ApoA-I Infusion Therapies Following Acute Coronary Syndrome: Past, Present, and Future

PURPOSE OF REVIEW

The elevated adverse cardiovascular event rate among patients with low high-density lipoprotein cholesterol (HDL-C) formed the basis for the hypothesis that elevating HDL-C would reduce those events. Attempts to raise endogenous HDL-C levels, however, have consistently failed to show improvements in cardiovascular outcomes. However, steady-state HDL-C concentration does not reflect the function of this complex family of particles. Indeed, HDL functions correlate only weakly with serum HDL-C concentration. Thus, the field has pivoted from simply raising the quantity of HDL-C to a focus on improving the putative anti-atherosclerotic functions of HDL particles. Such functions include the ability of HDL to promote the efflux of cholesterol from cholesterol-laden macrophages. Apolipoprotein A-I (apoA-I), the signature apoprotein of HDL, may facilitate the removal of cholesterol from atherosclerotic plaque, reduce the lesional lipid content and might thus stabilize vulnerable plaques, thereby reducing the risk of cardiac events. Infusion of preparations of apoA-I may improve cholesterol efflux capacity (CEC). This review summarizes the development of apoA-I therapies, compares their structural and functional properties and discusses the findings of previous studies including their limitations, and how CSL112, currently being tested in a phase III trial, may overcome these challenges.

RECENT FINDINGS

Three major ApoA-I-based approaches (MDCO-216, CER-001, and CSL111/CSL112) have aimed to enhance reverse cholesterol transport. These three therapies differ considerably in both lipid and protein composition. MDCO-216 contains recombinant ApoA-I Milano, CER-001 contains recombinant wild-type human ApoA-I, and CSL111/CSL112 contains native ApoA-I isolated from human plasma. Two of the three agents studied to date (apoA-1 Milano and CER-001) have undergone evaluation by intravascular ultrasound imaging, a technique that gauges lesion volume well but does not assess other important variables that may relate to clinical outcomes. ApoA-1 Milano and CER-001 reduce lecithin-cholesterol acyltransferase (LCAT) activity, potentially impairing the function of HDL in reverse cholesterol transport. Furthermore, apoA-I Milano can compete with and alter the function of the recipient's endogenous apoA-I. In contrast to these agents, CSL112, a particle formulated using human plasma apoA-I and phosphatidylcholine, increases LCAT activity and does not lead to the malfunction of endogenous apoA-I. CSL112 robustly increases cholesterol efflux, promotes reverse cholesterol transport, and now is being tested in a phase III clinical trial. Phase II-b studies of MDCO-216 and CER-001 failed to produce a significant reduction in coronary plaque volume as assessed by IVUS. However, the investigation to determine whether the direct infusion of a reconstituted apoA-I reduces post-myocardial infarction coronary events is being tested using CSL112, which is dosed at a higher level than MDCO-216 and CER-001 and has more favorable pharmacodynamics.

Nanodisc delivery of liver X receptor agonist for the treatment of diabetic nephropathy

Dyslipidemia is recognized to be an important contributor to the progression of diabetic nephropathy (DN), leading to lipoprotein dysregulation, excessive mesangium expansion as well as inflammation in the glomeruli. Thus, dual targeting of abnormal cholesterol metabolism and inflammatory responses of mesangial cells represents an alternative approach for DN treatment. Herein, we sought to develop a renal-targeting therapeutic strategy for diabetic nephropathy by modifying synthetic high-density lipoprotein (sHDL) nanodiscs with a kidney targeting ligand (KT peptide) and encapsulating a liver X receptor (LXR) agonist in the modified sHDL. LXR agonists delivered by sHDL can facilitate the removal of excessive lipids from mesangial cells, ameliorate inflammation and restore normal renal function. Overall, our data suggests that our optimized KT-targeted sHDL/TO nanodiscs (KT-sHDL/TO) generate potent therapeutic efficacy not only by more efficient cholesterol efflux, but also by suppressing mesangial cell proliferation. Most importantly, in a DN murine model, KT-sHDL/TO ameliorated dyslipidemia and inflammation superior to blank sHDL and non-targeting sHDL/TO formulations, showing promise for future clinical translation in DN treatment.

Inflammation and atherosclerosis: signaling pathways and therapeutic intervention

Atherosclerosis is a chronic inflammatory vascular disease driven by traditional and nontraditional risk factors. Genome-wide association combined with clonal lineage tracing and clinical trials have demonstrated that innate and adaptive immune responses can promote or quell atherosclerosis. Several signaling pathways, that are associated with the inflammatory response, have been implicated within atherosclerosis such as NLRP3 inflammasome, toll-like receptors, proprotein convertase subtilisin/kexin type 9, Notch and Wnt signaling pathways, which are of importance for atherosclerosis development and regression. Targeting inflammatory pathways, especially the NLRP3 inflammasome pathway and its regulated inflammatory cytokine interleukin-1β, could represent an attractive new route for the treatment of atherosclerotic diseases. Herein, we summarize the knowledge on cellular participants and key inflammatory signaling pathways in atherosclerosis, and discuss the preclinical studies targeting these key pathways for atherosclerosis, the clinical trials that are going to target some of these processes, and the effects of quelling inflammation and atherosclerosis in the clinic.

Antiatherosclerotic Effects of CSL112 Mediated by Enhanced Cholesterol Efflux Capacity

Approximately 12% of patients with acute myocardial infarction (AMI) experience a recurrent major adverse cardiovascular event within 1 year of their primary event, with most occurring within the first 90 days. Thus, there is a need for new therapeutic approaches that address this 90-day post-AMI high-risk period. The formation and eventual rupture of atherosclerotic plaque that leads to AMI is elicited by the accumulation of cholesterol within the arterial intima. Cholesterol efflux, a mechanism by which cholesterol is removed from plaque, is predominantly mediated by apolipoprotein A-I, which is rapidly lipidated to form high-density lipoprotein in the circulation and has atheroprotective properties. In this review, we outline how cholesterol efflux dysfunction leads to atherosclerosis and vulnerable plaque formation, including inflammatory cell recruitment, foam cell formation, the development of a lipid/necrotic core, and degradation of the fibrous cap. CSL112, a human plasma-derived apolipoprotein A-I, is in phase 3 of clinical development and aims to reduce the risk of recurrent cardiovascular events in patients with AMI in the first 90 days after the index event by increasing cholesterol efflux. We summarize evidence from preclinical and clinical studies suggesting that restoration of cholesterol efflux by CSL112 can stabilize plaque by several anti-inflammatory/immune-regulatory processes. These effects occur rapidly and could stabilize vulnerable plaques in patients who have recently experienced an AMI, thereby reducing the risk of recurrent major adverse cardiovascular events in the high-risk early post-AMI period.

CSL112 (Apolipoprotein A-I [Human]) Strongly Enhances Plasma Apoa-I and Cholesterol Efflux Capacity in Post-Acute Myocardial Infarction Patients: A PK/PD Substudy of the AEGIS-I Trial

Introduction:

Cholesterol efflux capacity (CEC) is impaired following acute myocardial infarction (AMI). CSL112 is an intravenous preparation of human plasma-derived apoA-I formulated with phosphatidylcholine (PC). CSL112 is intended to improve CEC and thereby prevent early recurrent cardiovascular events following AMI. AEGIS-I (ApoA-I Event Reducing in Ischemic Syndromes I) was a multicenter, randomized, double-blind, placebo-controlled, dose-ranging phase 2b study, designed to evaluate the hepatic and renal safety of CSL112. Here, we report an analysis of a pharmacokinetic (PK) and pharmacodynamic (PD) substudy of AEGIS-I.

Methods:

AMI patients were stratified by renal function and randomized 3:3:2 to 4, weekly, 2-hour infusions of low- and high-dose (2 g and 6 g) CSL112, or placebo. PK/PD assessments included plasma concentrations of apoA-I and PC, and measures of total and ABCA1-dependent CEC, as well as lipids/lipoproteins including high density lipoprotein cholesterol (HDL-C), non-HDL-C, low density lipoprotein cholesterol (LDL-C), ApoB, and triglycerides. Inflammatory and cardio-metabolic biomarkers were also evaluated.

Results:

The substudy included 63 subjects from AEGIS-I. CSL112 infusions resulted in rapid, dose-dependent increases in baseline corrected apoA-I and PC, which peaked at the end of the infusion (Tmax ≈ 2 hours). Similarly, there was a dose-dependent elevation in both total CEC and ABCA1-mediated CEC. Mild renal impairment did not affect the PK or PD of CSL112. CSL112 administration was also associated with an increase in plasma levels of HDL-C but not non-HDL-C, LDL-C, apoB, or triglycerides. No dose-effects on inflammatory or cardio-metabolic biomarkers were observed.

Conclusion:

Among patients with AMI, impaired CEC was rapidly elevated by CSL112 infusions in a dose-dependent fashion, along with an increase in apoA-I plasma concentrations. Findings from the current sub-study of the AEGIS-I support a potential atheroprotective benefit of CSL112 for AMI patients.

HDL and reverse cholesterol transport in humans and animals: Lessons from pre-clinical models and clinical studies

The ability to accept cholesterol from cells and to promote reverse cholesterol transport (RCT) represents the best characterized antiatherogenic function of HDL. Studies carried out in animal models have unraveled the multiple mechanisms by which these lipoproteins drive cholesterol efflux from macrophages and cholesterol uptake to the liver. Moreover, the influence of HDL composition and the role of lipid transporters have been clarified by using suitable transgenic models or through experimental design employing pharmacological or nutritional interventions. Cholesterol efflux capacity (CEC), an in vitro assay developed to offer a measure of the first step of RCT, has been shown to associate with cardiovascular risk in several human cohorts, supporting the atheroprotective role of RCT in humans as well. However, negative data in other cohorts have raised concerns on the validity of this biomarker. In this review we will present the most relevant data documenting the role of HDL in RCT, as assessed in classical or innovative methodological approaches.

Efficacy and Safety of High-Density Lipoprotein/Apolipoprotein A1 Replacement Therapy in Humans and Mice With Atherosclerosis: A Systematic Review and Meta-Analysis

Background: Although elevation of HDL-C levels by pharmaceutical drugs have no benefit of cardiovascular endpoint, the effect of high-density lipoprotein/apolipoprotein A1 (HDL/apoA-1) replacement therapy on atherosclerosis is controversial. The current meta-analysis analyzed the effects of HDL/apoA-1 replacement therapies on atherosclerotic lesions both in humans and mice.

Methods: The PubMed, Cochrane Library, Web of Science, and EMBASE databases were searched through June 6, 2020. The methodological quality of the human studies was assessed using Review Manager (RevMan, version 5.3.). The methodological quality of the mouse studies was assessed using a stair list. STATA (version 14.0) was used to perform all statistical analyses.

Results: Fifteen randomized controlled human trials and 17 animal studies were included. The pooled results showed that HDL/apoA-1 replacement therapy use did not significantly decrease the percent atheroma volume (p = 0.766) or total atheroma volume (p = 0.510) in acute coronary syndrome (ACS) patients (N = 754). However, HDL/apoA-1 replacement therapies were significantly associated with the final percent lesion area, final lesion area, and changes in lesion area (SMD, −1.75; 95% CI: −2.21~-1.29, p = 0.000; SMD, −0.78; 95% CI: −1.18~-0.38, p = 0.000; SMD: −2.06; 95% CI, −3.92~-0.2, p = 0.03, respectively) in mice.

Conclusions: HDL/apoA-1 replacement therapies are safe but do not significantly improve arterial atheroma volume in humans. The results in animals suggest that HDL/apoA-1 replacement therapies decrease the lesion area. Additional studies are needed to investigate and explain the differences in HDL/apoA-1 replacement therapy efficacies between humans and animals.

Trial registration number: Human pooled analysis: PROSPERO, CRD42020210772. prospectively registered.

Lipids and Lipoproteins in Health and Disease: Focus on Targeting Atherosclerosis

Despite advances in pharmacotherapy, intervention devices and techniques, residual cardiovascular risks still cause a large burden on public health. Whilst most guidelines encourage achieving target levels of specific lipids and lipoproteins to reduce these risks, increasing evidence has shown that molecular modification of these lipoproteins also has a critical impact on their atherogenicity. Modification of low-density lipoprotein (LDL) by oxidation, glycation, peroxidation, apolipoprotein C-III adhesion, and the small dense subtype largely augment its atherogenicity. Post-translational modification by oxidation, carbamylation, glycation, and imbalance of molecular components can reduce the capacity of high-density lipoprotein (HDL) for reverse cholesterol transport. Elevated levels of triglycerides (TGs), apolipoprotein C-III and lipoprotein(a), and a decreased level of apolipoprotein A-I are closely associated with atherosclerotic cardiovascular disease. Pharmacotherapies aimed at reducing TGs, lipoprotein(a), and apolipoprotein C-III, and enhancing apolipoprotein A-1 are undergoing trials, and promising preliminary results have been reported. In this review, we aim to update the evidence on modifications of major lipid and lipoprotein components, including LDL, HDL, TG, apolipoprotein, and lipoprotein(a). We also discuss examples of translating findings from basic research to potential therapeutic targets for drug development.

Reconstituted HDL as a therapeutic delivery device

Studies of "pre β" high density lipoprotein (HDL) and reconstituted HDL (rHDL) have contributed to our understanding of the Reverse Cholesterol Transport pathway. The relative ease with which discoidal rHDL can be generated in vitro has led to novel applications including a) infusion of rHDL into patients to promote regression of atherosclerosis; b) use of rHDL as a miniature membrane for integration of transmembrane proteins in a native-like conformation and c) incorporation of hydrophobic bioactive molecules into rHDL, creating a delivery device. The present review is focused on bioactive agent containing rHDL. The broad array of hydrophobic bioactive molecules successfully incorporated into these particles is discussed, as well as the use of natural lipids and synthetic lipid analogs to confer distinctive binding activity. This technology remains in its infancy with the full potential of these simple, yet elegant, nanoparticles still to be discovered.

Artificial high-density lipoprotein-mimicking nanotherapeutics for the treatment of cardiovascular diseases

Despite the ability of current efficacious low-density lipoprotein-cholesterol-lowering therapies to reduce total cardiovascular disease (CVD) risks, CVD still poses major risks for morbidity and mortality to the general population. Because of the pleiotropic endothelial protective effects of high-density lipoproteins (HDL), the direct infusion of reconstituted HDL (rHDL) products, including MDCO-216, CER001, and CSL112, have been tested in clinical trials to determine whether direct infusion of rHDL can reduce coronary events in CVD patients. In addition to these rHDL products, in the past two decades, there has been an increased focused on designing artificial HDL-mimicking nanotherapeutics to produce complementary therapeutic strategies for CVD patients beyond lowering of atherogenic lipoproteins. Although recent reviews have comprehensively discussed the developments of artificial HDL-mimicking nanoparticles as therapeutics for CVD, there has been little assessment of "plain" or "drug-free" HDL-mimicking nanoparticles as therapeutics alone. In this review, we will summarize the clinical outcomes of rHDL products, examine recent advances in other types of artificial HDL-mimicking nanotherapeutics, including polymeric nanoparticles, cyclodextrins, micelles, metal nanoparticles, and so on; and potential new approaches for future CVD interventions. Moreover, success stories, lessons, and interpretations of the utility and functionality of these HDL-mimicking nanotherapeutics will be an integral part of this article. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease.

Co-administration of CSL112 (apolipoprotein A-I [human]) with atorvastatin and alirocumab is not associated with increased hepatotoxic or toxicokinetic effects in rats

CSL112 (apolipoprotein A-I, apo AI [human]) is an investigational drug in Phase 3 development for risk reduction of early recurrent cardiovascular events following an acute myocardial infarction (AMI). Although CSL112 is known to be well tolerated with a regimen of four weekly 6 g intravenous infusions after AMI, high doses of reconstituted apo AI preparations can transiently elevate liver enzymes in rats, raising the possibility of additive liver toxicity and toxicokinetic (TK) effects upon co-administration with cholesterol-lowering drugs, i.e., HMG-CoA reductase and proprotein convertase subtilisin/kexin type 9 inhibitors. We performed a toxicity and TK study in CD rats assigned to eleven treatment groups, including two dose levels of intravenous (IV) CSL112 (140 mg/kg, low-dose; 600 mg/kg, high-dose) administered as a single dose, alone or with intravenous alirocumab 50 mg/kg/week and/or oral atorvastatin 10 mg/kg/day. In addition, control groups of atorvastatin and alirocumab alone and in combination were investigated. Results showed some liver enzyme elevations (remaining <2-fold of baseline) related to administration of CSL112 alone. There was limited evidence of an additive effect of CSL112 on liver enzymes when combined, at either dose level, with alirocumab and/or atorvastatin, and histology revealed no evidence of an increased incidence or severity of hepatocyte vacuolation compared to the control treatments. Co-administration of the study drugs had minimal effect on their respective exposure levels, and on levels of total cholesterol and high-density lipoprotein cholesterol. These data support concomitant use of CSL112 with alirocumab and/or atorvastatin with no anticipated negative impact on liver safety and TK.

(r)HDL in theranostics: how do we apply HDL's biology for precision medicine in atherosclerosis management?

High-density lipoproteins (HDL) are key players in cholesterol metabolism homeostasis since they are responsible for transporting excess cholesterol from peripheral tissues to the liver. Imbalance in this process, due to either excessive accumulation or impaired clearance, results in net cholesterol accumulation and increases the risk of cardiovascular disease (CVD). Therefore, significant effort has been focused on the development of therapeutic tools capable of either directly or indirectly enhancing HDL-guided reverse cholesterol transport (RCT). More recently, in light of the emergence of precision nanomedicine, there has been renewed research interest in attempting to take advantage of the development of advanced recombinant HDL (rHDL) for both therapeutic and diagnostic purposes. In this review, we provide an update on the different approaches that have been developed using rHDL, focusing on the rHDL production methodology and rHDL applications in theranostics. We also compile a series of examples highlighting potential future perspectives in the field.

Apolipoprotein-AI and AIBP synergetic anti-inflammation as vascular diseases therapy: the new perspective

Vascular diseases (VDs) including pulmonary arterial hypertension (PAH), atherosclerosis (AS) and coronary arterial diseases (CADs) contribute to the higher morbidity and mortality worldwide. Apolipoprotein A-I (Apo A-I) binding protein (AIBP) and Apo-AI negatively correlate with VDs. However, the mechanism by which AIBP and apo-AI regulate VDs still remains unexplained. Here, we provide an overview of the role of AIBP and apo-AI regulation of vascular diseases molecular mechanisms such as vascular energy homeostasis imbalance, oxidative and endoplasmic reticulum stress and inflammation in VDs. In addition, the role of AIBP and apo-AI in endothelial cells (ECs), vascular smooth muscle (VSMCs) and immune cells activation in the pathogenesis of VDs are explained. The in-depth understanding of AIBP and apo-AI function in the vascular system may lead to the discovery of VDs therapy.

High Density Lipoprotein Cholesterol Efflux Capacity and Atherosclerosis in Cardiovascular Disease: Pathophysiological Aspects and Pharmacological Perspectives

Over the years, the relationship between high-density lipoprotein (HDL) and atherosclerosis, initially highlighted by the Framingham study, has been revealed to be extremely complex, due to the multiple HDL functions involved in atheroprotection. Among them, HDL cholesterol efflux capacity (CEC), the ability of HDL to promote cell cholesterol efflux from cells, has emerged as a better predictor of cardiovascular (CV) risk compared to merely plasma HDL-cholesterol (HDL-C) levels. HDL CEC is impaired in many genetic and pathological conditions associated to high CV risk such as dyslipidemia, chronic kidney disease, diabetes, inflammatory and autoimmune diseases, endocrine disorders, etc. The present review describes the current knowledge on HDL CEC modifications in these conditions, focusing on the most recent human studies and on genetic and pathophysiologic aspects. In addition, the most relevant strategies possibly modulating HDL CEC, including lifestyle modifications, as well as nutraceutical and pharmacological interventions, will be discussed. The objective of this review is to help understanding whether, from the current evidence, HDL CEC may be considered as a valid biomarker of CV risk and a potential pharmacological target for novel therapeutic approaches.

Recent advances in nanomaterials for therapy and diagnosis for atherosclerosis

Atherosclerosis is a chronic inflammatory disease driven by lipid accumulation in arteries, leading to narrowing and thrombosis. It affects the heart, brain, and peripheral vessels and is the leading cause of mortality in the United States. Researchers have strived to design nanomaterials of various functions, ranging from non-invasive imaging contrast agents, targeted therapeutic delivery systems to multifunctional nanoagents able to target, diagnose, and treat atherosclerosis. Therefore, this review aims to summarize recent progress (2017-now) in the development of nanomaterials and their applications to improve atherosclerosis diagnosis and therapy during the preclinical and clinical stages of the disease.

Physico-chemical and physiological determinants of lipo-nanoparticle stability

Liposome-based nanoparticles (NPs) comprised mostly of phospholipids (PLs) have been developed to deliver diagnostic and therapeutic agents. Whereas reassembled plasma lipoproteins have been tested as NP carriers of hydrophobic molecules, they are unstable because the components can spontaneously transfer to other PL surfaces-cell membranes and lipoproteins-and can be degraded by plasma lipases. Here we review two strategies for NP stabilization. One is to use PLs that contain long acyl-chains: according to a quantitative thermodynamic model and in vivo tests, increasing the chain length of a PL reduces the spontaneous transfer rate and increases plasma lifetime. A second strategy is to substitute ether for ester bonds which makes the PLs lipase resistant. We conclude with recommendations of simple ex vivo and in vitro tests of NP stability that should be conducted before in vivo tests are begun.

Rationale and design of ApoA-I Event Reducing in Ischemic Syndromes II (AEGIS-II): A phase 3, multicenter, double-blind, randomized, placebo-controlled, parallel-group study to investigate the efficacy and safety of CSL112 in subjects after acute myocardial infarction

Acute myocardial infarction (MI) patients remain at high risk for recurrent events. Cholesterol efflux, mediated by apolipoprotein A-I, removes excess cholesterol from atherosclerotic plaque and transports it to the liver for excretion. Impaired cholesterol efflux is associated with higher cardiovascular (CV) event rates among both patients with stable coronary artery disease and recent MI. CSL112, a novel intravenous formulation of apolipoprotein A-I (human) derived from human plasma, increases cholesterol efflux capacity. AEGIS-II is a phase 3, multicenter, double-blind, randomized, placebo-controlled, parallel-group trial investigating the efficacy and safety of CSL112 compared to placebo among high-risk acute MI participants. Eligibility criteria include age ≥ 18 years with type 1 (spontaneous) MI, evidence of multivessel stable coronary artery disease, and presence of diabetes requiring pharmacotherapy, or ≥2 of the following: age ≥ 65 years, prior MI, or peripheral artery disease. A target sample of 17,400 participants will be randomized 1:1 to receive 4 weekly infusions of CSL112 6 g or placebo, initiated prior to or on the day of discharge and within 5 days of first medical contact. The primary outcome is the time to first occurrence of the composite of CV death, MI, or stroke through 90 days. Key secondary outcomes include the total number of hospitalizations for coronary, cerebral, or peripheral ischemia through 90 days and time to first occurrence of the composite primary outcome through 180 and 365 days. AEGIS-II will be the first trial to formally test whether enhancing cholesterol efflux can reduce the rate of recurrent major adverse CV events.

Pharmacometric analyses to characterize the effect of CSL112 on apolipoprotein A-I and cholesterol efflux capacity in acute myocardial infarction patients

AIMS

To characterize relationships between apolipoprotein A-I (apoA-I) exposure and cholesterol efflux capacity (CEC) and covariate effects following CSL112 (apoA-I [human]) administration in an integrated population including acute myocardial infarction (AMI) patients.

METHODS

A pharmacometric analysis utilized data from seven clinical trials, including patients with AMI, subjects with renal impairment and healthy subjects. A population pharmacokinetic (PK) analysis was performed to relate CSL112 doses to changes in apoA-I plasma concentrations. Covariate analysis was conducted to identify sources of variability in apoA-I exposure. Exposure-response modeling was conducted to describe the relationship between apoA-I exposure and total or ATP binding cassette transporter A1-(ABCA1)-dependent CEC and to identify clinical predictors of CEC.

RESULTS

A two-compartment model described apoA-I PK. ApoA-I clearance was slightly lower in subjects with AMI, whereas baseline apoA-I was marginally higher in female and Japanese subjects. Covariate effects on apoA-I exposure were in the order of 10% and thus not clinically relevant. The relationships between apoA-I exposure and CECs were described by nonlinear models. Simulations showed CEC elevation resulting from apoA-I exposure increment was comparable in AMI and non-AMI subjects; no covariate had clinically meaningful effects on CEC. Simulations also demonstrated that CEC in patients with AMI post 6 g CSL112 dosing was substantially elevated compared to placebo and lower dose levels.

CONCLUSIONS

The model-based exposure-response analysis demonstrated, irrespective of body weight, sex and race, that fixed 6 g CSL112 dosing causes a desired CEC elevation, which may benefit AMI patients by potentially reducing early recurrent cardiovascular event risk.

The Rise and Fall "ing" of the HDL Hypothesis

Earlier epidemiological studies have shown an inverse correlation between high-density lipoprotein cholesterol (HDLc) and coronary heart disease (CHD). This observation along with the finding that reverse cholesterol transport is mediated by HDL, supported the hypothesis that the HDL molecule has a cardioprotective role. More recently, epidemiological data suggest a U-shaped curve correlating HDLc and CHD. In addition, randomized clinical trials of drugs that significantly increase plasma HDLc levels, such as nicotinic acid and cholesterol ester transfer protein (CETP) inhibitors failed to show a reduction in major adverse cardiovascular events. These observations challenge the hypothesis that HDL has a cardioprotective role. It is possible that HDL quality and function is optimal only when de novo synthesis of apo A-I occurs. Inhibition of turnover of HDL with currently available agents yields HDL molecules that are ineffective in reverse cholesterol transport. To test this hypothesis, newer therapeutic drugs that increase de novo production of HDL and apo A-I should be tested in clinical trials.

Reconfiguring Nature's Cholesterol Accepting Lipoproteins as Nanoparticle Platforms for Transport and Delivery of Therapeutic and Imaging Agents

Apolipoproteins are critical structural and functional components of lipoproteins, which are large supramolecular assemblies composed predominantly of lipids and proteins, and other biomolecules such as nucleic acids. A signature feature of apolipoproteins is the preponderance of amphipathic α-helical motifs that dictate their ability to make extensive non-covalent inter- or intra-molecular helix-helix interactions in lipid-free states or helix-lipid interactions with hydrophobic biomolecules in lipid-associated states. This review focuses on the latter ability of apolipoproteins, which has been capitalized on to reconstitute synthetic nanoscale binary/ternary lipoprotein complexes composed of apolipoproteins/peptides and lipids that mimic native high-density lipoproteins (HDLs) with the goal to transport drugs. It traces the historical development of our understanding of these nanostructures and how the cholesterol accepting property of HDL has been reconfigured to develop them as drug-loading platforms. The review provides the structural perspective of these platforms with different types of apolipoproteins and an overview of their synthesis. It also examines the cargo that have been loaded into the core for therapeutic and imaging purposes. Finally, it lays out the merits and challenges associated with apolipoprotein-based nanostructures with a future perspective calling for a need to develop "zip-code"-based delivery for therapeutic and diagnostic applications.

HDL inhibits endoplasmic reticulum stress-induced apoptosis of pancreatic β-cells in vitro by activation of Smoothened

Loss of pancreatic β-cell mass and function as a result of sustained ER stress is a core step in the pathogenesis of diabetes mellitus type 2. The complex control of β-cells and insulin production involves hedgehog (Hh) signaling pathways as well as cholesterol-mediated effects. In fact, data from studies in humans and animal models suggest that HDL protects against the development of diabetes through inhibition of ER stress and β-cell apoptosis. We investigated the mechanism by which HDL inhibits ER stress and apoptosis induced by thapsigargin, a sarco/ER Ca²⁺-ATPase inhibitor, in β-cells of a rat insulinoma cell line, INS1e. We further explored effects on the Hh signaling receptor Smoothened (SMO) with pharmacologic agonists and inhibitors. Interference with sterol synthesis or efflux enhanced β-cell apoptosis and abrogated the anti-apoptotic activity of HDL. During ER stress, HDL facilitated the efflux of specific oxysterols, including 24-hydroxycholesterol (OHC). Supplementation of reconstituted HDL with 24-OHC enhanced and, in cells lacking ABCG1 or the 24-OHC synthesizing enzyme CYP46A1, restored the protective activity of HDL. Inhibition of SMO countered the beneficial effects of HDL and also LDL, and SMO agonists decreased β-cell apoptosis in the absence of ABCG1 or CYP46A1. The translocation of the SMO-activated transcription factor glioma-associated oncogene GLI-1 was inhibited by ER stress but restored by both HDL and 24-OHC. In conclusion, the protective effect of HDL to counter ER stress and β-cell death involves the transport, generation, and mobilization of oxysterols for activation of the Hh signaling receptor SMO.

High-Density Lipoprotein in Lupus: Disease Biomarkers and Potential Therapeutic Strategy

Systemic lupus erythematosus (SLE) patients exhibit accelerated development of atherosclerosis and increased incidents of cardiovascular disease (CVD) that cannot be explained by traditional risk factors alone. Accumulating evidence suggests that reduced levels of high-density lipoproteins (HDLs), along with altered HDL composition and function, may contribute to the accelerated atherosclerosis in SLE patients. Normally, HDLs play various atheroprotective roles through facilitating cholesterol efflux, inhibiting vascular inflammation, and scavenging oxidative species. However, systemic inflammation, oxidative stress, and autoimmunity in SLE patients induce changes in HDL size distribution and proteomic and lipidomic signatures. These compositional changes in HDLs result in the formation of proinflammatory, dysfunctional HDL. These lupus-altered HDLs have impaired antiatherogenic function with reduced cholesterol efflux capacities, impaired antioxidation abilities, and diminished antiinflammatory properties. In fact, dysfunctional HDL may promote atherogenesis by inducing inflammation. Thus, dysfunctional HDLs could be an important biomarker of accelerated atherosclerosis in lupus. Additionally, HDL-targeted therapies, especially infusion of reconstituted HDLs, may serve as a potential therapeutic intervention for SLE patients with CVD.

Search for Natural Compounds That Increase Apolipoprotein A-I Transcription in HepG2 Cells: Specific Attention for BRD4 Inhibitors

Although increasing apolipoprotein A‐I (apoA‐I) might lower the cardiovascular disease risk, knowledge on natural compounds that elevate apoA‐I transcription is limited. Therefore, the aim of this study was to discover natural compounds that increase apoA‐I transcription in HepG2 cells. Since BRD4 inhibition is known to elevate apoA‐I transcription, we focused on natural BRD4 inhibitors. For this, the literature was screened for compounds that might increase apoA‐I and or inhibit BRD4. This resulted in list A, (apoA‐I increasers with unknown BRD4 inhibitor capacity), list B (known BRD4 inhibitors that increase apoA‐I), and list C (BRD4 inhibitors with unknown effect on apoA‐I). These compounds were compared with the compounds in two natural compound databases. This resulted in (1) a common substructure (ethyl‐benzene) in 60% of selected BRD4‐inhibitors, and (2) four compounds that increased ApoA‐I: hesperetin, equilenin, 9(S)‐HOTrE, and cymarin. Whether these increases are regulated via BRD4 inhibition and the ethyl‐benzene structure inhibits BRD4 requires further study.

Phospholipid Component Defines Pharmacokinetic and Pharmacodynamic Properties of Synthetic High-Density Lipoproteins

Synthetic high-density lipoprotein (sHDL) nanoparticles composed of apolipoprotein A-I mimetic peptide and phospholipids have been shown to reduce atherosclerosis in animal models. Cholesterol is mobilized from atheroma macrophages by sHDL into the blood compartment and delivered to the liver for elimination. Historically, sHDL drug discovery efforts were focused on optimizing peptide sequences for interaction with cholesterol cellular transporters rather than understanding how both sHDL components, peptide and lipid, influence its pharmacokinetic and pharmacodynamic profiles. We designed two sets of sHDL having either identical phospholipid but variable peptide sequences with different plasma stability or identical peptide and phospholipids with variable fatty acid chain length and saturation. We found that sHDL prepared with proteolytically stable 22A-P peptide had 2-fold longer circulation half-time relative to the less stable 22A peptide. Yet, longer half-life did not translate into any improvement in cholesterol mobilization. In contrast, sHDL with variable phospholipid compositions showed significant differences in phospholipid PK, with distearoyl phosphatidylcholine-based sHDL demonstrating the longest half-life of 6.0 hours relative to 1.0 hour for palmitoyl-oleoyl phosphatidylcholine-based sHDL. This increase in half-life corresponded to an approx. 6.5-fold increase in the area under the curve for the mobilized cholesterol. Therefore, the phospholipid component in sHDL plays a major role in cholesterol mobilization in vivo and should not be overlooked in the design of future sHDL. SIGNIFICANCE STATEMENT: The phospholipid composition in sHDL plays a critical role in determining half-life and cholesterol mobilization in vivo.

Novel lipid-modifying therapies addressing unmet needs in cardiovascular disease

Cardiovascular disease (CVD) remains a major cause of morbidity and mortality worldwide. Currently, it is well established that dyslipidemia is one of the major risk factors leading to the development of atherosclerosis and CVD. Statins remain the standard-of-care in the treatment of hypercholesterolemia and their use has significantly reduced cardiovascular morbidity and mortality. In addition, recent advances in lipid-modifying therapies, such as the development of proprotein convertase subtilisin/kexin type 9 inhibitors, have further improved cardiovascular outcomes in patients with hypercholesterolemia. However, despite significant progress in the treatment of dyslipidemia, there is still considerable residual risk of recurring cardiovascular events. Furthermore, in some cases, an effective therapy for the identified primary cause of a specific dyslipidemia has not been found up to date. Thus, a number of novel pharmacological interventions are under early human trials, targeting different molecular pathways of lipid formation, regulation and metabolism. This editorial aims to discuss the current clinical and scientific data on new promising lipid-modifying therapies addressing unmet needs in CVD, which may prove beneficial in the near future.

Synthetic high-density lipoprotein nanoparticles for the treatment of Niemann-Pick diseases

BACKGROUND

Niemann-Pick disease type C is a fatal and progressive neurodegenerative disorder characterized by the accumulation of unesterified cholesterol in late endosomes and lysosomes. We sought to develop new therapeutics for this disorder by harnessing the body's endogenous cholesterol scavenging particle, high-density lipoprotein (HDL).

METHODS

Here we design, optimize, and define the mechanism of action of synthetic HDL (sHDL) nanoparticles.

RESULTS

We demonstrate a dose-dependent rescue of cholesterol storage that is sensitive to sHDL lipid and peptide composition, enabling the identification of compounds with a range of therapeutic potency. Peripheral administration of sHDL to Npc1 I1061T homozygous mice mobilizes cholesterol, reduces serum bilirubin, reduces liver macrophage size, and corrects body weight deficits. Additionally, a single intraventricular injection into adult Npc1 I1061T brains significantly reduces cholesterol storage in Purkinje neurons. Since endogenous HDL is also a carrier of sphingomyelin, we tested the same sHDL formulation in the sphingomyelin storage disease Niemann-Pick type A. Utilizing stimulated Raman scattering microscopy to detect endogenous unlabeled lipids, we show significant rescue of Niemann-Pick type A lipid storage.

CONCLUSIONS

Together, our data establish that sHDL nanoparticles are a potential new therapeutic avenue for Niemann-Pick diseases.

Development, synthesis, and 68Ga-Labeling of a Lipophilic complexing agent for atherosclerosis PET imaging

Cardiovascular disease is the leading cause of mortality and morbidity worldwide. Atherosclerosis accounts for 50% of deaths in western countries. This multifactorial pathology is characterized by the accumulation of lipids and inflammatory cells within the vascular wall, leading to plaque formation. We describe herein the synthesis of a PCTA-based ⁶⁸Ga³⁺ chelator coupled to a phospholipid biovector 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE), which is the main constituent of the phospholipid moiety of High-Density Lipoprotein (HDL) phospholipid moiety. The resulting ⁶⁸Ga-PCTA-DSPE inserted into HDL particles was compared to ¹⁸F-FDG as a PET agent to visualize atherosclerotic plaques. Our agent markedly accumulated within mouse atheromatous aortas and more interestingly in human endarterectomy carotid samples. These results support the potential use of ⁶⁸Ga-PCTA-DSPE-HDL for atherosclerosis PET imaging.

Apolipoprotein A1 is associated with SYNTAX score in patients with a non-ST segment elevation myocardial infarction

BACKGROUND

The study was designed to investigate lipid profile and SYNTAX score in patients with non-ST segment elevation myocardial infarction (NSTEMI).

METHODS

311 patients with NSTEMI were enrolled. The demographic, clinical data, blood samples and SYNTAX score were documented. The Pearson linear correlation was used to detect confounding factors linearly correlated with SYNTAX score. The significantly correlated confounding factors were put into the multiple linear regressions.

RESULTS

The Pearson linear correlation showed that high-density lipoprotein- cholesterol (HDL-C) and apolipoprotein A1 (ApoA1) were significantly correlated with Syntax Score (r = - 0.119, P = 0.044 and r = - 0.182, P = 0.002, respectively). The multiple linear regressions for Syntax Score were built using HDL-C and ApoA1, respectively. After the adjustment of other significantly correlated confounding factors such as white blood cell count (WBC), myohemoglobin (MB), glutamic-oxalacetic transaminase (AST) and creatinine, the ApoA1 still showed significant association with Syntax Score (β = - 0.151, P = 0.028). The area under curve was (AUC) 0.624 and the optimal cutoff value is 1.07 g/L when using ApoA1 to predict moderate and severe coronary artery lesions. The patients with ApoA1 ≥ 1.07 g/L and < 1.07 g/L have the Syntax Scores of 12.21 ± 11.58 and 16.33 ± 11.53, respectively (P = 0.001).

CONCLUSIONS

The ApoA1 is the only lipid factor significantly associated with complexity of coronary artery lesion in patients with NSTEMI, the patients with ApoA1 < 1.07 g/L may have more complex coronary artery lesions.

Artificial High Density Lipoprotein Nanoparticles in Cardiovascular Research

Lipoproteins are endogenous nanoparticles which are the major transporter of fats and cholesterol in the human body. They play a key role in the regulatory mechanisms of cardiovascular events. Lipoproteins can be modified and manipulated to act as drug delivery systems or nanocarriers for contrast agents. In particular, high density lipoproteins (HDL), which are the smallest class of lipoproteins, can be synthetically engineered either as nascent HDL nanodiscs or spherical HDL nanoparticles. Reconstituted HDL (rHDL) particles are formed by self-assembly of various lipids and apolipoprotein AI (apo-AI). A variety of substances including drugs, nucleic acids, signal emitting molecules, or dyes can be loaded, making them efficient nanocarriers for therapeutic applications or medical diagnostics. This review provides an overview about synthesis techniques, physicochemical properties of rHDL nanoparticles, and structural determinants for rHDL function. We discuss recent developments utilizing either apo-AI or apo-AI mimetic peptides for the design of pharmaceutical rHDL formulations. Advantages, limitations, challenges, and prospects for clinical translation are evaluated with a special focus on promising strategies for the treatment and diagnosis of atherosclerosis and cardiovascular diseases.

The future of apolipoprotein E mimetic peptides in the prevention of cardiovascular disease

PURPOSE OF REVIEW

This review aims to discuss the recent developments in the area of apolipoprotein E (apoE) mimetics and their therapeutic potential for treating cardiovascular disease, the leading cause of mortality worldwide.

RECENT FINDINGS

Ongoing research efforts target the development of novel therapies that would not only reduce circulating levels of atherogenic lipoproteins, but could also increase high density lipoprotein cholesterol (HDL-C) levels and/or improve HDL function. Among them, synthetic peptides that mimic the structure of natural human apoE, a component of triglyceride-rich lipoproteins and HDL, have been designed and proven to be functionally similar to apoE. In specific, apoE mimetic peptides mediate hepatic clearance of circulating atherogenic lipoproteins, dramatically reduce plasma cholesterol, and lead to attenuation of atherosclerosis development in vivo. These peptides also exhibit pleiotropic antiatherogenic properties, such as macrophage cholesterol efflux capacity, as well as anti-inflammatory and antioxidative functions.

SUMMARY

ApoE mimetics are undergoing preclinical and clinical evaluation with promising results to date that render them attractive candidates in cardiovascular disease prevention and treatment.

Apolipoprotein A-I Protects Against Pregnancy-Induced Insulin Resistance in Rats

Objective- Insulin resistance and inflammation in pregnancy are risk factors for gestational diabetes mellitus. Increased plasma HDL (high-density lipoprotein) and apo (apolipoprotein) A-I levels have been reported to improve glucose metabolism and inhibit inflammation in animals and humans. This study asks whether increasing plasma apoA-I levels improves insulin sensitivity and reduces inflammation in insulin-resistant pregnant rats. Approach and Results- Insulin-resistant pregnant rats received intravenous infusions of lipid-free apoA-I (8 mg/kg) or saline on days 6, 9, 12, 15, and 18 of pregnancy. The rats were then subjected to a euglycemic-hyperinsulinemic clamp. Glucose uptake was increased in white and brown adipose tissue by 57±13% and 32±10%, respectively ( P<0.05 for both), and in quadriceps and gastrocnemius muscle by 35±9.7% and 47±14%, respectively ( P<0.05 for both), in the apoA-I-treated pregnant rats relative to saline-infused pregnant rats. The pregnant rats that were treated with apoA-I also had reduced plasma TNF-α (tumor necrosis factor-α) levels by 57±8.4%, plasma IL (interleukin)-6 levels by 67±9.5%, and adipose tissue macrophage content by 54±8.2% ( P<0.05 for all) relative to the saline-treated pregnant rats. Conclusions- These studies establish that apoA-I protects against pregnancy-induced insulin resistance in rats by increasing insulin sensitivity in adipose tissue and skeletal muscle and inhibiting inflammation. This identifies apoA-I as a potential target for preventing pregnancy-induced insulin resistance and reducing the incidence of gestational diabetes mellitus.