Regression of coronary atherosclerosis with infusions of the high-density lipoprotein mimetic CER-001 in patients with more extensive plaque burden

Targeting the vivid facets of apolipoproteins as a cardiovascular risk factor in rheumatoid arthritis

Mostly, cardiovascular diseases are blamed for casualties in rheumatoid arthritis (RA) patients. Customarily, dyslipidemia is probably the most prevalent underlying cause of untimely demise in people suffering from RA as it hastens the expansion of atherosclerosis. The engagement of inflammatory cytokines like tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), etc., is crucial in the progression and proliferation of both RA and abnormal lipid parameters. Thus, lipid abnormalities should be monitored frequently in patients with both primary and advanced RA stages. An advanced lipid profile examination, i.e., direct role of apolipoproteins associated with various lipid molecules is a more dependable approach for better understanding of the disease and selecting suitable therapeutic targets. Therefore, studying their apolipoproteins is more relevant than assessing RA patients' altered lipid profile levels. Among the various apolipoprotein classes, Apo A1 and Apo B are primarily being focused. In addition, it also addresses how calculating Apo B:Apo A1 ratio can aid in analyzing the disease's risk. The marketed therapies available to control lipid abnormalities are associated with many other risk factors. Hence, directly targeting Apo A1 and Apo B would provide a better and safer option.

High-density lipoprotein infusion therapy: A review

Increased cholesterol-rich, low-density, non-calcified atheromas as assessed by computer coronary tomography angiography analyses have been shown to predict myocardial infarction significantly better than coronary artery calcium score or the presence of obstructive coronary artery disease (CAD) as evaluated with standard coronary angiography. Low serum high-density lipoprotein (HDL) cholesterol values are an independent risk factor for CAD. Very small, lipid-poor preβ-1 HDL particles have been shown to be most effective in promoting cellular cholesterol efflux. HDL infusions have been documented to reduce aortic atherosclerosis in cholesterol-fed animal models. However, human studies using infusions of either the HDL mimetic containing recombinant apolipoprotein (apo) A-I Milano or Cerenis Compound-001 with native recombinant apoA-I have been mainly negative in promoting coronary atherosclerosis progression as assessed by intravascular ultrasound. In contrast, a study using 7 weekly infusions of autologous delipidated HDL in six homozygous familial hypercholesterolemic patients was effective in promoting significant regression of low-density non-calcified coronary atheroma regression as assessed by computed coronary angiography. This therapy has received Food and Drug Administration approval. Commonwealth Serum Laboratories has carried out a large clinical endpoint trial using an HDL complex (native apoA-I with phospholipid), and the results were negative. Our purpose is to review animal and human studies using various forms of HDL infusion therapy to promote regression of atherosclerosis. In our view, differences in results may be due to: 1) the HDL preparations used, 2) the subjects studied, and 3) the methods used to assess coronary atherosclerosis.

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.

The pleiotropic effects of high-density lipoproteins and apolipoprotein A-I

The high density lipoprotein (HDL) fraction of human plasma consists of multiple subpopulations of spherical particles that are structurally uniform, but heterogeneous in terms of size, composition and function. Numerous epidemiological studies have established that an elevated high density lipoprotein cholesterol (HDL-C) level is associated with decreased cardiovascular risk. However, with several recent randomised clinical trials of HDL-C raising agents failing to reduce cardiovascular events, contemporary research is transitioning towards clinical development of the cardioprotective functions of HDLs and the identification of functions that can be exploited for treatment of other diseases. This review describes the origins of HDLs and the causes of their compositional and functional heterogeneity. It then summarises current knowledge of how cardioprotective and other functions of HDLs are regulated. The final section of the review summarises recent advances in the clinical development of HDL-targeted therapies.

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.

Phosphatidylserine enhances anti-inflammatory effects of reconstituted HDL in macrophages via distinct intracellular pathways

Phosphatidylserine (PS) is a minor phospholipid constituent of high-density lipoprotein (HDL) that exhibits potent anti-inflammatory activity. It remains indeterminate whether PS incorporation can enhance anti-inflammatory effects of reconstituted HDL (rHDL). Human macrophages were treated with rHDL containing phosphatidylcholine alone (PC-rHDL) or PC and PS (PC/PS-rHDL). Interleukin (IL)-6 secretion and expression was more strongly inhibited by PC/PS-rHDL than PC-rHDL in both tumor necrosis factor (TNF)-α- and lipopolysaccharide (LPS)-stimulated macrophages. siRNA experiments revealed that the enhanced anti-inflammatory effects of PC/PS-rHDL required scavenger receptor class B type I (SR-BI). Furthermore, PC/PS-rHDL induced a greater increase in Akt1/2/3 phosphorylation than PC-rHDL. In addition, PC/PS but not PC-rHDL decreased the abundance of plasma membrane lipid rafts and p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation. Finally, when these rHDL formulations were administered to dyslipidemic low-density lipoprotein (LDL)-receptor knockout mice fed a high-cholesterol diet, circulating IL-6 levels were significantly reduced only in PC/PS-rHDL-treated mice. In parallel, enhanced Akt1/2/3 phosphorylation by PC/PS-rHDL was observed in the mouse aortic tissue using immunohistochemistry. We concluded that the incorporation of PS into rHDLs enhanced their anti-inflammatory activity by modulating Akt1/2/3- and p38 MAPK-mediated signaling through SR-BI in stimulated macrophages. These data identify PS as a potent anti-inflammatory component capable of enhancing therapeutic potential of rHDL-based therapy.

The Role of High-Density Lipoprotein Cholesterol in 2022

PURPOSE OF THE REVIEW

High-density lipoproteins (HDL) are responsible for the transport in plasma of a large fraction of circulating lipids, in part from tissue mobilization. The evaluation of HDL-associated cholesterol (HDL-C) has provided a standard method for assessing cardiovascular (CV) risk, as supported by many contributions on the mechanism of this arterial benefit. The present review article will attempt to investigate novel findings on the role and mechanism of HDL in CV risk determination.

RECENT FINDINGS

The most recent research has been aimed to the understanding of how a raised functional capacity of HDL, rather than elevated levels per se, may be responsible for the postulated CV protection. Markedly elevated HDL-C levels appear instead to be associated to a raised coronary risk, indicative of a U-shaped relationship. While HDL-C reduction is definitely related to a raised CV risk, HDL-C elevations may be linked to non-vascular diseases, such as age-related macular disease. The description of anti-inflammatory, anti-oxidative and anti-infectious properties has indicated potential newer areas for diagnostic and therapeutic approaches. In the last two decades inconclusive data have arisen from clinical trials attempting to increase HDL-C pharmacologically or by way of recombinant protein infusions (most frequently with the mutant A-I _Milano); prevention of stent occlusion or heart failure treatment have shown instead significant promise. Targeted clinical studies are still ongoing.

Plaque microstructures during metformin therapy in type 2 diabetic subjects with coronary artery disease: optical coherence tomography analysis

BACKGROUND

While metformin is recommended as a first-line cardioprotective therapy for type 2 diabetic patients, whether it exerts direct effects on atherosclerotic plaque remains uncertain. The current study characterized coronary plaque microstructures in type 2 diabetic patients who received metformin.

METHODS

We retrospectively analyzed 409 non-culprit lipid plaques in 313 type 2 diabetic patients with coronary artery disease (CAD) by using frequency-domain optical coherence tomography (FD-OCT) imaging. FD-OCT derived plaque microstructures were compared in patients stratified according to metformin use.

RESULTS

A proportion of 38.6% of study subjects received metformin. Patients receiving metformin more likely exhibited a history of hypertension (79.3% vs. 67.1%, P=0.03) and metabolic syndrome (52.8% vs. 36.4%, P=0.01). On FD-OCT imaging, the prevalence of lipid plaque was lower in the metformin group (66.2% vs. 77.9%, P=0.03). Furthermore, the metformin group demonstrated plaques with a smaller lipid arc (median: 168.7° vs. 208.5°, P=0.008), shorter longitudinal length (media: 5.1 vs. 9.1 mm, P=0.04), and a lower frequency of cholesterol crystal (3.9% vs. 18.2%, P=0.01) and spotty calcification (3.9% vs. 34.8%, P=0.008). These differences remained significant after adjusting for clinical characteristics and glycemic control. However, in patients who received insulin, the favourable effect of metformin on lipid arc was not observed (insulin user: P=0.87; insulin non-user: P=0.009; P value for interaction between two groups, P=0.02).

CONCLUSIONS

Metformin use was associated with a lower prevalence of vulnerable plaque features in type 2 diabetic patients with CAD, especially insulin non-user. These findings suggest the potential of metformin to exert direct plaque stabilization effects in type 2 diabetic subjects.

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.

(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.

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.

CER-001 ameliorates lipid profile and kidney disease in a mouse model of familial LCAT deficiency

OBJECTIVE

CER-001 is an HDL mimetic that has been tested in different pathological conditions, but never with LCAT deficiency. This study was designed to investigate whether the absence of LCAT affects the catabolic fate of CER-001, and to evaluate the effects of CER-001 on kidney disease associated with LCAT deficiency.

METHODS

Lcat^-/- and wild-type mice received CER-001 (2.5, 5, 10 mg/kg) intravenously for 2 weeks. The plasma lipid/ lipoprotein profile and HDL subclasses were analyzed. In a second set of experiments, Lcat^-/- mice were injected with LpX to induce renal disease and treated with CER-001 and then the plasma lipid profile, lipid accumulation in the kidney, albuminuria and glomerular podocyte markers were evaluated.

RESULTS

In Lcat^-/- mice a decrease in total cholesterol and triglycerides, and an increase in HDL-c was observed after CER-001 treatment. While in wild-type mice CER-001 entered the classical HDL remodeling pathway, in the absence of LCAT it disappeared from the plasma shortly after injection and ended up in the kidney. In a mouse model of renal disease in LCAT deficiency, treatment with CER-001 at 10 mg/kg for one month had beneficial effects not only on the lipid profile, but also on renal disease, by limiting albuminuria and podocyte dysfunction.

CONCLUSIONS

Treatment with CER-001 ameliorates the dyslipidemia typically associated with LCAT deficiency and more importantly limits renal damage in a mouse model of renal disease in LCAT deficiency. The present results provide a rationale for using CER-001 in FLD patients.

Lipid efflux mechanisms, relation to disease and potential therapeutic aspects

Lipids are hydrophobic and amphiphilic molecules involved in diverse functions such as membrane structure, energy metabolism, immunity, and signaling. However, altered intra-cellular lipid levels or composition can lead to metabolic and inflammatory dysfunction, as well as lipotoxicity. Thus, intra-cellular lipid homeostasis is tightly regulated by multiple mechanisms. Since most peripheral cells do not catabolize cholesterol, efflux (extra-cellular transport) of cholesterol is vital for lipid homeostasis. Defective efflux contributes to atherosclerotic plaque development, impaired β-cell insulin secretion, and neuropathology. Of these, defective lipid efflux in macrophages in the arterial walls leading to foam cell and atherosclerotic plaque formation has been the most well studied, likely because a leading global cause of death is cardiovascular disease. Circulating high density lipoprotein particles play critical roles as acceptors of effluxed cellular lipids, suggesting their importance in disease etiology. We review here mechanisms and pathways that modulate lipid efflux, the role of lipid efflux in disease etiology, and therapeutic options aimed at modulating this critical process.

Cholesterol membrane content has a ubiquitous evolutionary function in immune cell activation: the role of HDL

PURPOSE OF REVIEW

Cellular cholesterol content influences the structure and function of lipid rafts, plasma membrane microdomains essential for cell signaling and activation. HDL modulate cellular cholesterol efflux, thus limiting cholesterol accumulation and controlling immune cell activation. Aim of this review is to discuss the link between HDL and cellular cholesterol metabolism in immune cells and the therapeutic potential of targeting cholesterol removal from cell membranes.

RECENT FINDINGS

The inverse relationship between HDL-cholesterol (HDL-C) levels and the risk of cardiovascular disease has been recently challenged by observations linking elevated levels of HDL-C with increased risk of all-cause mortality, infections and autoimmune diseases, paralleled by the failure of clinical trials with HDL-C-raising therapies. These findings suggest that improving HDL function might be more important than merely raising HDL-C levels. New approaches aimed at increasing the ability of HDL to remove cellular cholesterol have been assessed for their effect on immune cells, and the results have suggested that this could be a new effective approach.

SUMMARY

Cholesterol removal from plasma membrane by different means affects the activity of immune cells, suggesting that approaches aimed at increasing the ability of HDL to mobilize cholesterol from cells would represent the next step in HDL biology.

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.

Effect of Serial Infusions of CER-001, a Pre-β High-Density Lipoprotein Mimetic, on Coronary Atherosclerosis in Patients Following Acute Coronary Syndromes in the CER-001 Atherosclerosis Regression Acute Coronary Syndrome Trial: A Randomized Clinical Trial

Importance

CER-001 is a negatively charged, engineered pre-β high-density lipoprotein (HDL) mimetic containing apolipoprotein A-I and sphingomyelin. Preliminary studies demonstrated favorable effects of CER-001 on cholesterol efflux and vascular inflammation. A post hoc reanalysis of a previously completed study of intravenous infusion of CER-001, 3 mg/k, showed that the intravenous infusion in patients with a high coronary plaque burden promoted regression as assessed by intravascular ultrasonography.

Objective

To determine the effect of infusing CER-001 on coronary atherosclerosis progression in statin-treated patients.

Design, Setting, and Participants

A double-blind, randomized, multicenter trial evaluating the effect of 10 weekly intravenous infusions of CER-001, 3 mg/kg, (n = 135) or placebo (n = 137) in patients with an acute coronary syndrome (ACS) and baseline percent atheroma volume (PAV) greater than 30% in the proximal segment of an epicardial artery by intravascular ultrasonography. The study included 34 academic and community hospitals in Australia, Hungary, the Netherlands, and the United States in patients with ACS presenting for coronary angiography. Patients were enrolled from August 15, 2015, to November 19, 2016.

Interventions

Participants were randomized to receive weekly CER-001, 3 mg/kg, or placebo for 10 weeks in addition to statins.

Main Outcomes and Measures

The primary efficacy measure was the nominal change in PAV from baseline to day 78 measured by serial intravascular ultrasonography imaging. The secondary efficacy measures were nominal change in normalized total atheroma volume and percentage of patients demonstrating plaque regression. Safety and tolerability were also evaluated.

Results

Among 293 patients (mean [SD] age, 59.8 [9.4] years; 217 men [79.8%] and 261 white race/ethnicity [96.0%]), 86 (29%) had statin prior use prior to the index ACS and 272 (92.8%) had evaluable imaging at follow-up. The placebo and CER-001 groups had similar posttreatment median levels of low-density lipoprotein cholesterol (74 mg/dL vs 79 mg/dL; P = .15) and high-density lipoprotein cholesterol (43 mg/dL vs 44 mg/dL; P = .66). The primary efficacy measure, PAV, decreased 0.41% with placebo (P = .005 compared with baseline), but not with CER-001 (-0.09%; P = .67 compared with baseline; between group differences, 0.32%; P = .15). Similar percentages of patients in the placebo and CER-001 groups demonstrated regression of PAV (57.7% vs 53.3%; P = .49). Infusions were well tolerated, with no differences in clinical and laboratory adverse events observed between treatment groups.

Conclusions and Relevance

Infusion of CER-001 did not promote regression of coronary atherosclerosis in statin-treated patients with ACS and high plaque burden.

Trial Registration

ClinicalTrials.gov Identifier: NCT2484378.

Lipid management in patients with chronic kidney disease

An increased risk of cardiovascular disease, independent of conventional risk factors, is present even at minor levels of renal impairment and is highest in patients with end-stage renal disease (ESRD) requiring dialysis. Renal dysfunction changes the level, composition and quality of blood lipids in favour of a more atherogenic profile. Patients with advanced chronic kidney disease (CKD) or ESRD have a characteristic lipid pattern of hypertriglyceridaemia and low HDL cholesterol levels but normal LDL cholesterol levels. In the general population, a clear relationship exists between LDL cholesterol and major atherosclerotic events. However, in patients with ESRD, LDL cholesterol shows a negative association with these outcomes at below average LDL cholesterol levels and a flat or weakly positive association with mortality at higher LDL cholesterol levels. Overall, the available data suggest that lowering of LDL cholesterol is beneficial for prevention of major atherosclerotic events in patients with CKD and in kidney transplant recipients but is not beneficial in patients requiring dialysis. The 2013 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for Lipid Management in CKD provides simple recommendations for the management of dyslipidaemia in patients with CKD and ESRD. However, emerging data and novel lipid-lowering therapies warrant some reappraisal of these recommendations.

Inheritance of high and low HDL: mechanisms and management

PURPOSE OF REVIEW

The inverse association between plasma high-density lipoprotein cholesterol (HDL-C) concentration and the incidence of cardiovascular disease (CVD) has been unequivocally proven by many epidemiological studies. There are several genetic disorders affecting HDL-C plasma levels, either providing atheroprotection or predisposing to premature atherosclerosis. However, up to date, there has not been any pharmacological intervention modulating HDL-C levels, which has been clearly shown to prevent the progression of CVD. Thus, clarifying the exact underlying mechanisms of inheritance of these genetic disorders that affect HDL is a current goal of the research, as key roles of molecular components of HDL metabolism and function can be revealed and become targets for the discovery of novel medications for the prevention and treatment of CVD.

RECENT FINDINGS

Primary genetic disorders of HDL can be either associated with longevity or, in contrast, may lead to premature CVD, causing high morbidity and mortality to their carriers. A large body of recent research has closely examined the genetic disorders of HDL and new promising therapeutic strategies have been developed, which may be proven beneficial in patients predisposed to CVD in the near future.

SUMMARY

We have reviewed recent findings on the inheritance of genetic disorders associated with high and low HDL-C plasma levels and we have discussed their clinical features, as well as information about new promising HDL-C-targeted therapies that are under clinical trials.

Supramolecular Assembly of High-Density Lipoprotein Mimetic Nanoparticles Using Lipid-Conjugated Core Scaffolds

Synthetic high-density lipoprotein (HDL) mimics have emerged as promising therapeutic agents. However, approaches to date have been unable to reproduce key features of spherical HDLs, which are the most abundant human HDL species. Here, we report the synthesis and characterization of spherical HDL mimics using lipid-conjugated organic core scaffolds. The core design motif constrains and orients phospholipid geometry to facilitate the assembly of soft-core nanoparticles that are approximately 10 nm in diameter and resemble human HDLs in their size, shape, surface chemistry, composition, and protein secondary structure. These particles execute salient HDL functions, including efflux of cholesterol from macrophages, cholesterol delivery to hepatocytes, support lecithin:cholesterol acyltransferase activity, and suppress inflammation. These results represent a significant step toward a genuine functional mimic of human HDLs.

Infusions of Large Synthetic HDL Containing Trimeric apoA-I Stabilize Atherosclerotic Plaques in Hypercholesterolemic Rabbits

BACKGROUND

Among strategies to reduce the remaining risk of cardiovascular disease, interest has focused on using infusions of synthetic high-density lipoprotein (sHDL).

METHODS

New Zealand rabbits underwent a perivascular injury at both carotids and were randomly allocated into 2 protocols: (1) a single-dose study, where rabbits were treated with a single infusion of sHDL containing a trimeric form of human apoA-I (TN-sHDL, 200 mg/kg) or with Placebo; (2) a multiple-dose study, where 4 groups of rabbits were treated 5 times with Placebo or TN-sHDL at different doses (8, 40, 100 mg/kg). Plaque changes were analysed in vivo by intravascular ultrasound. Blood was drawn from rabbits for biochemical analyses and cholesterol efflux capacity evaluation.

RESULTS

In both protocols, atheroma volume in the Placebo groups increased between the first and the second intravascular ultrasound evaluation. A stabilization or a slight regression was instead observed vs baseline in the TN-sHDL-treated groups (P < 0.005 vs Placebo after infusion). TN-sHDL treatment caused a sharp rise of plasma-free cholesterol levels and a significant increase of total cholesterol efflux capacity. Histologic analysis of carotid plaques showed a reduced macrophage accumulation in TN-sHDL-treated rabbits compared with Placebo (P < 0.05).

CONCLUSIONS

Our results demonstrate that acute and subacute treatments with TN-sHDL are effective in stabilizing atherosclerotic plaques in a rabbit model. This effect appears to be related to a reduced intraplaque accumulation of inflammatory cells. Besides recent failures in proving its efficacy, sHDL treatment remains a fascinating therapeutic option for the reduction of cardiovascular risk.

Dual inhibition of endothelial miR-92a-3p and miR-489-3p reduces renal injury-associated atherosclerosis

BACKGROUND AND AIMS

Cardiovascular disease (CVD) is the leading cause of death in chronic kidney disease (CKD) patients, however, the underlying mechanisms that link CKD and CVD are not fully understood and limited treatment options exist in this high-risk population. microRNAs (miRNA) are critical regulators of gene expression for many biological processes in atherosclerosis, including endothelial dysfunction and inflammation. We hypothesized that renal injury-induced endothelial miRNAs promote atherosclerosis. Here, we demonstrate that dual inhibition of endothelial miRNAs inhibits atherosclerosis in the setting of renal injury.

METHODS

Aortic endothelial miRNAs were analyzed in apolipoprotein E-deficient (Apoe-/-) mice with renal damage (5/6 nephrectomy, 5/6Nx) by real-time PCR. Endothelial miR-92a-3p and miR-489-3p were inhibited by locked-nucleic acid (LNA) miRNA inhibitors complexed to HDL.

RESULTS

Renal injury significantly increased endothelial miR-92a-3p levels in Apoe-/-;5/6Nx mice. Dual inhibition of miR-92a-3p and miR-489-3p in Apoe-/-;5/6Nx with a single injection of HDL + LNA inhibitors significantly reduced atherosclerotic lesion area by 28.6% compared to HDL + LNA scramble (LNA-Scr) controls. To examine the impact of dual LNA treatment on aortic endothelial gene expression, total RNA sequencing was completed, and multiple putative target genes and pathways were identified to be significantly altered, including the STAT3 immune response pathway. Among the differentially expressed genes, Tgfb2 and Fam220a were identified as putative targets of miR-489-3p and miR-92a-3p, respectively. Both Tgfb2 and Fam220a were significantly increased in aortic endothelium after miRNA inhibition in vivo compared to HDL + LNA-Scr controls. Furthermore, Tgfb2 and Fam220a were validated with gene reporter assays as direct targets of miR-489-3p and miR-92a-3p, respectively. In human coronary artery endothelial cells, over-expression and inhibition of miR-92a-3p decreased and increased FAM220A expression, respectively. Moreover, miR-92a-3p overexpression increased STAT3 phosphorylation, likely through direct regulation of FAM220A, a negative regulator of STAT3 phosphorylation.

CONCLUSIONS

These results support endothelial miRNAs as therapeutic targets and dual miRNA inhibition as viable strategy to reduce CKD-associated atherosclerosis.

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.

Reconstituted Discoidal High-Density Lipoproteins: Bioinspired Nanodiscs with Many Unexpected Applications

PURPOSE OF REVIEW

Summarize the initial discovery of discoidal high-density lipoprotein (HDL) in human plasma and review more recent innovations that span the use of reconstituted nanodisc HDL for membrane protein characterization to its use as a drug carrier and a novel therapeutic agent for cardiovascular disease.

RECENT FINDINGS

Using a wide variety of biophysical techniques, the structure and composition of endogenous discoidal HDL have now largely been solved. This has led to the development of new methods for the in vitro reconstitution of nanodisc HDL, which have proven to have a wide variety of biomedical applications. Nanodisc HDL has been used as a platform for mimicking the plasma membrane for the reconstitution and investigation of the structures of several plasma membrane proteins, such as cytochrome P450s and ABC transporters. Nanodisc HDL has also been designed as drug carriers to transport amphipathic, as well as hydrophobic small molecules, and has potential therapeutic applications for several diseases. Finally, nanodisc HDL itself like native discoidal HDL can mediate cholesterol efflux from cells and are currently being tested in late-stage clinical trials for cardiovascular disease. The discovery of the characterization of native discoidal HDL has inspired a new field of synthetic nanodisc HDL, which has offered a growing number of unanticipated biomedical applications.

Translating Evidence of HDL and Plaque Regression

Considerable evidence from preclinical and population studies suggests that HDLs (high-density lipoproteins) possess atheroprotective properties. Reports from HDL infusion studies in animals and early clinical imaging trials reported evidence of plaque regression. These findings have stimulated further interest in developing new agents targeting HDL. However, the results of more recent imaging studies in the setting of high-intensity statin use have been disappointing. As the concept of plaque changes with HDL therapeutics evolves and imaging technology to evaluate these effects advances, there will become increasing opportunity to determine the effects of HDL agents on atherosclerotic plaque (Graphic Abstract).

HDL Mimetics Infusion and Regression of Atherosclerosis: Is It Still Considered a Valid Therapeutic Option?

Purpose of Review

This review aims to summarize and discuss the recent findings in the field of using HDL mimetics for the treatment of patients with coronary artery disease.

Recent Findings

Following the largely disappointing results with the cholesteryl ester transfer protein inhibitors, focus moved to HDL functionality rather than absolute HDL cholesterol values. A number of HDL/apoA-I mimicking molecules were developed, aiming to enhance reverse cholesterol transport that has been associated with an atheroprotective effect. Three HDL mimetics have made the step from bench-testing to clinical trials in humans and are discussed here: apoA-I Milano, CSL-112, and CER-001. Unfortunately, with the exception of CSL-112 where the results of the clinical trial are not yet known, none of the agents was able to demonstrate a clinical benefit.

Summary

HDL mimetics have failed to date to prove a beneficial effect in clinical practice. Reverse cholesterol transport remains a challenging therapeutic pathway to be explored.

High-Density Lipoprotein Infusions

High-density lipoproteins (HDLs) have presented an attractive target for development of new therapies for cardiovascular prevention on the basis of epidemiology and preclinical studies demonstrating their protective properties. Development of HDL mimetics provides an opportunity to administer functional HDL. However, clinical trials have produced variable results, with no evidence to date that they reduce cardiovascular events. This article reviews development programs of HDL mimetics.

[Pharmacological targets for dislipidemies correction. Opportunities and prospects of therapeutic usage]

Literature data on influence of existing and new groups of drug preparations for dyslipidemias correction are systemized, and molecular mechanisms of their effects are reviewed. The results of experimental and clinical investigations aimed at revealing of new pharmacological targets of dyslipidemias correction were analyzed. The approaches for activation of high density lipoproteins functionality are described. The implementation of alternative preparations with new alternative mechanisms of action may be suggested to improve the effectiveness of traditional treatment in the future.

Hypercholesterolaemia - practical information for non-specialists

Hypercholesterolaemia is amongst the most common conditions encountered in the medical profession. It remains one of the key modifiable cardiovascular risk factors and there have been recent advances in the risk stratification methods and treatment options available. In this review, we provide a background into hypercholesterolaemia for non-specialists and consider the merits of the different risk assessment tools available. We also provide detailed considerations as to: i) when to start treatment, ii) what targets to aim for and iii) the role of low density lipoprotein cholesterol.

Development of CER-001: Preclinical Dose Selection Through to Phase I Clinical Findings

Background

CER-001 comprises recombinant human apolipoprotein A-I complexed with phospholipids that mimics natural, nascent, pre-β high-density lipoprotein (HDL). We present animal model data showing dose-dependent increases in cholesterol efflux with CER-001 and its subsequent elimination by reverse lipid transport, together with inhibition of atherosclerotic plaque progression. We report the first phase I study results with CER-001 in humans, starting at 0.25 mg/kg, which is 1/80th of the safe dose (20 mg/kg) established in 4-week multiple-dose animal studies dosed every second day.

Methods

Healthy volunteers, 18–55 years old with a low-density lipoprotein-cholesterol:HDL-cholesterol ratio greater than 3.0, received single intravenous escalating doses of CER-001 (0.25–45.0 mg/kg) and placebo in a double-blind randomised cross-over fashion. Subjects were followed up for 3 weeks post-dose. Assessments included adverse event monitoring, blood sampling, and clinical laboratory measurements.

Results

Thirty-two subjects were enrolled. All CER-001 doses (0.25–45 mg/kg) were safe and well tolerated, with an adverse event profile similar to placebo. Effects on clinical chemistry, haematology and coagulation parameters were comparable to placebo. No adverse effects of CER-001 on electrocardiograms were observed. No antibodies to apolipoprotein A-I were detected following single-dose administration of CER-001. Plasma apolipoprotein A-I levels increased in a dose-related manner and returned to baseline by 24 h post-dose for doses up to 10 mg/kg but remained in circulation for >72 h post-dose for doses >10 mg/kg. CER-001 caused elevations in plasma cholesterol and total and unesterified cholesterol in the HDL fraction. Mobilisation of unesterified cholesterol in the HDL fraction was seen with CER-001 at doses as low as 2 mg/kg.

Conclusion

CER-001 is well tolerated when administered to humans as single doses up to 45 mg/kg and mobilises and eliminates cholesterol via reverse lipid transport.

Electronic supplementary material

The online version of this article (doi:10.1007/s40261-017-0506-3) contains supplementary material, which is available to authorized users.

Effect of serial infusions of reconstituted high-density lipoprotein (CER-001) on coronary atherosclerosis: rationale and design of the CARAT study

BACKGROUND

High-density lipoprotein (HDL) is believed to have atheroprotective properties, but an effective HDL-based therapy remains elusive. Early studies have suggested that infusion of reconstituted HDL promotes reverse cholesterol transport and vascular reactivity. The CER-001 Atherosclerosis Regression Acute Coronary Syndrome Trial (CARAT) is investigating the impact of infusing an engineered pre-beta HDL mimetic containing sphingomyelin (SM) and dipalmitoyl phosphatidlyglycerol (CER-001) on coronary atheroma volume in patients with a recent acute coronary syndrome (ACS).

METHODS

The CARAT is a phase 2, multicenter trial in which 292 patients with an ACS undergoing intracoronary ultrasonography and showing percent atheroma volume (PAV) greater than 30% are randomly assigned to treatment with ten infusions of CER-001 3 mg/kg or matching placebo, administered at weekly intervals. Intracoronary ultrasonography is repeated at the end of the treatment period.

RESULTS

The primary endpoint is the nominal change in PAV. Safety and tolerability will also be evaluated.

CONCLUSIONS

CARAT will establish whether serial 3 mg/kg infusions of an engineered pre-beta HDL mimetic containing SM and dipalmitoyl phosphatidlyglycerol (CER-001) will regress atherosclerotic plaque in patients with a recent ACS.