CSL112 Infusion Rapidly Increases APOA1 Exchange Rate via Specific Serum Amyloid-Poor HDL Subpopulations When Administered to Patients Post-Myocardial Infarction.

BACKGROUND: To characterize the effects of CSL112 (human APOA1 [apolipoprotein A1]) on the APOA1 exchange rate (AER) and the relationships with specific HDL (high-density lipoprotein) subpopulations when administered in the 90-day high-risk period post-acute myocardial infarction. METHODS: A subset of patients (n=50) from the AEGIS-I (ApoA-I Event Reducing in Ischemic Syndromes I) study received either placebo or CSL112 post-acute myocardial infarction. AER was measured in AEGIS-I plasma samples incubated with lipid-sensitive fluorescent APOA1 reporter. HDL particle size distribution was assessed by native gel electrophoresis followed by fluorescent imaging and detection of APOA1 and SAA (serum amyloid A) by immunoblotting. RESULTS: CSL112 infusion increased AER peaking at 2 hours and returning to baseline 24 hours post-infusion. AER correlated with cholesterol efflux capacity (r=0.49), HDL-cholesterol (r=0.30), APOA1 (r=0.48), and phospholipids (r=0.48; all P<0.001) over all time points. Mechanistically, changes in cholesterol efflux capacity and AER induced by CSL112 reflected HDL particle remodeling resulting in increased small HDL species that are highly active in mediating ABCA1 (ATP-binding cassette transporter 1)-dependent efflux, and large HDL species with high capacity for APOA1 exchange. The lipid-sensitive APOA1 reporter predominantly exchanged into SAA-poor HDL particles and weakly incorporated into SAA-enriched HDL species. CONCLUSIONS: Infusion of CSL112 enhances metrics of HDL functionality in patients with acute myocardial infarction. This study demonstrates that in post-acute myocardial infarction patients, HDL-APOA1 exchange involves specific SAA-poor HDL populations. Our data suggest that progressive enrichment of HDL with SAA may generate dysfunctional particles with impaired HDL-APOA1 exchange capacity, and that infusion of CSL112 improves the functional status of HDL with respect to HDL-APOA1 exchange. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02108262.

Biological basis and proposed mechanism of action of CSL112 (apolipoprotein A-I [human]) for prevention of major adverse cardiovascular events in patients with myocardial infarction.

Despite current standard of care treatment, the period shortly after acute myocardial infarction (AMI) is associated with high residual cardiovascular (CV) risk, with high rates of recurrent AMI and CV death in the first 90 days following the index event. This represents an area of high unmet need that may be potentially addressed by novel therapeutic agents that optimize high-density lipoprotein cholesterol (HDL-C) function rather than increase HDL-C concentrations. Apolipoprotein A-I (apoA-I) is the major constituent of HDL and a key mediator of cholesterol efflux from macrophages within atherosclerotic plaque, a property especially relevant during the high-risk period immediately following an AMI when cholesterol efflux capacity is found to be reduced. CSL112 is a novel formulation of human plasma-derived apolipoprotein A-I (apoA-I), currently being evaluated in a Phase 3 clinical trial (AEGIS-II) for the reduction of major adverse CV events in the 90-day high-risk period post-AMI. In this review, we provide an overview of the biological properties of CSL112 that contribute to its proposed mechanism of action for potential therapeutic benefit. These properties include rapid and robust promotion of cholesterol efflux from cells abundant in atherosclerotic plaque, in addition to anti-inflammatory effects, which together, may have a stabilizing effect on atherosclerotic plaque. We provide a detailed overview of these mechanisms, in addition to information on the composition of CSL112 and how it is manufactured.

Inhibition of VEGF-B signaling prevents non-alcoholic fatty liver disease development by targeting lipolysis in the white adipose tissue.

BACKGROUND & AIMS: Hepatic steatosis is a hallmark of non-alcoholic fatty liver disease (NAFLD), a common comorbidity in type 2 diabetes mellitus (T2DM). The pathogenesis of NAFLD is complex and involves the crosstalk between the liver and the white adipose tissue (WAT). Vascular endothelial growth factor B (VEGF-B) has been shown to control tissue lipid accumulation by regulating the transport properties of the vasculature. The role of VEGF-B signaling and the contribution to hepatic steatosis and NAFLD in T2DM is currently not understood. METHODS: C57BL/6 J mice treated with a neutralizing antibody against VEGF-B, or mice with adipocyte-specific overexpression or under-expression of VEGF-B (AdipoqCre+/VEGF-BTG/+ mice and AdipoqCre+/Vegfbfl/+mice) were subjected to a 6-month high-fat diet (HFD), or chow-diet, whereafter NAFLD development was assessed. VEGF-B expression was analysed in WAT biopsies from patients with obesity and NAFLD in a pre-existing clinical cohort (n = 24 patients with NAFLD and n = 24 without NAFLD) and correlated to clinicopathological features. RESULTS: Pharmacological inhibition of VEGF-B signaling in diabetic mice reduced hepatic steatosis and NAFLD by blocking WAT lipolysis. Mechanistically we show, by using HFD-fed AdipoqCre+/VEGF-BTG/+ mice and HFD-fed AdipoqCre+/Vegfbfl/+mice, that inhibition of VEGF-B signaling targets lipolysis in adipocytes. Reducing VEGF-B signaling ameliorated NAFLD by decreasing WAT inflammation, resolving WAT insulin resistance, and lowering the activity of the hormone sensitive lipase. Analyses of human WAT biopsies from individuals with NAFLD provided evidence supporting the contribution of VEGF-B signaling to NAFLD development. VEGF-B expression levels in adipocytes from two WAT depots correlated with development of dysfunctional WAT and NAFLD in humans. CONCLUSIONS: Taken together, our data from mouse models and humans suggest that VEGF-B antagonism may represent an approach to combat NAFLD by targeting hepatic steatosis through suppression of lipolysis. IMPACT AND IMPLICATIONS: Non-alcoholic fatty liver disease (NAFLD) is a common comorbidity in type 2 diabetes mellitus (T2DM) and has a global prevalence of between 25-29%. There are currently no approved drugs for NAFLD, and given the scale of the ongoing diabetes epidemics, there is an urgent need to identify new treatment options. Our work suggests that VEGF-B antagonism may represent an approach to combat NAFLD by targeting hepatic steatosis through suppression of lipolysis. The neutralizing anti-VEGF-B antibody, which was used in this study, has already entered clinical trials for patients with diabetes. Therefore, we believe that our results are of great general interest to a broad audience, including patients and patient organizations, the medical community, academia, the life science industry and the public.

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.

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.

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.

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.

Nascent HDL (High-Density Lipoprotein) Discs Carry Cholesterol to HDL Spheres: Effects of HDL Particle Remodeling on Cholesterol Efflux.

OBJECTIVE: To characterize the fate of protein and lipid in nascent HDL (high-density lipoprotein) in plasma and explore the role of interaction between nascent HDL and mature HDL in promoting ABCA1 (ATP-binding cassette transporter 1)-dependent cholesterol efflux. Approach and Results: Two discoidal species, nascent HDL produced by RAW264.7 cells expressing ABCA1 (LpA-I [apo AI containing particles formed by incubating ABCA1-expressing cells with apo AI]), and CSL112, human apo AI (apolipoprotein AI) reconstituted with phospholipids, were used for in vitro incubations with human plasma or purified spherical plasma HDL. Fluorescent labeling and biotinylation of HDL were employed to follow the redistribution of cholesterol and apo AI, cholesterol efflux was measured using cholesterol-loaded cells. We show that both nascent LpA-I and CSL112 can rapidly fuse with spherical HDL. Redistribution of the apo AI molecules and cholesterol after particle fusion leads to the formation of (1) enlarged, remodeled, lipid-rich HDL particles carrying lipid and apo AI from LpA-I and (2) lipid-poor apo AI particles carrying apo AI from both discs and spheres. The interaction of discs and spheres led to a greater than additive elevation of ABCA1-dependent cholesterol efflux. CONCLUSIONS: These data demonstrate that although newly formed discs are relatively poor substrates for ABCA1, they can interact with spheres to produce lipid-poor apo AI, a much better substrate for ABCA1. Because the lipid-poor apo AI generated in this interaction can itself become discoid by the action of ABCA1, cycles of cholesterol efflux and disc-sphere fusion may result in net ABCA1-dependent transfer of cholesterol from cells to HDL spheres. This process may be of particular importance in atherosclerotic plaque where cholesterol acceptors may be limiting.

Moderate Renal Impairment Does Not Impact the Ability of CSL112 (Apolipoprotein A-I [Human]) to Enhance Cholesterol Efflux Capacity.

CSL112 (apolipoprotein A-I [human]) is a novel intravenous formulation of plasma-derived apolipoprotein A-I (apoA-I) that enhances cholesterol efflux capacity. Renal impairment is a common comorbidity in acute myocardial infarction patients and is associated with impaired lipid metabolism. The aim of this phase 1 study was to assess the impact of moderate renal impairment on the pharmacokinetic and pharmacodynamic profile of CSL112. Sixteen subjects with moderate renal impairment and 16 age-, sex-, and weight-matched subjects with normal renal function participated in the study. Within each renal function cohort, subjects were randomized 3:1 to receive a single intravenous infusion of CSL112 2 g (n = 6) or placebo (n = 2) or CSL112 6 g (n = 6) or placebo (n = 2). At baseline, subjects with moderate renal impairment versus normal renal function had higher total cholesterol efflux, ABCA1-dependent cholesterol efflux capacity, and pre-ß1-high-density lipoprotein (HDL) levels. Infusing CSL112 resulted in similar, immediate, robust, dose-dependent elevations in apoA-I and cholesterol efflux capacity in both renal function cohorts and significantly greater elevations in pre-ß1-HDL (P < .05) in moderate renal impairment. Lecithin-cholesterol acyltransferase activity, demonstrated by a time-dependent change in the ratio of unesterified to esterified cholesterol, did not differ by renal function. No meaningful changes in proatherogenic lipid levels were observed. Moderate renal impairment did not impact the ability of CSL112 to enhance cholesterol efflux capacity. CSL112 may represent a novel therapy to reduce the risk of early recurrent cardiovascular events following acute myocardial infarction in patients with or without moderate renal impairment.

Pharmacokinetics and Safety of CSL112 (Apolipoprotein A-I [Human]) in Adults With Moderate Renal Impairment and Normal Renal Function.

CSL112 (Apolipoprotein A-I [human]) is an intravenous preparation of apolipoprotein A-I (apoA-I), formulated with phosphatidylcholine (PC) and stabilized with sucrose, in development to prevent early recurrent cardiovascular events following acute myocardial infarction (AMI). This phase 1 study was designed to determine if moderate renal impairment (RI) influenced the pharmacokinetics (PK) and safety of CSL112. Thirty-two subjects, 16 with moderate RI (estimated glomerular filtration rate [eGFR] ≥ 30 and < 60 mL/min/1.73 m2 ) and 16 age-, sex-, and weight-matched subjects with normal renal function (eGFR ≥ 90 mL/min/1.73 m2 ) were randomized 3:1 to receive a single infusion of CSL112 2 g (n = 6) or placebo (n = 2), or CSL112 6 g (n = 6) or placebo (n = 2). PK sampling was at prespecified times from 48 hours prior to 144 hours following infusions, with final safety assessments at 90 days. Renal and hepatic safety, and adverse events (AEs) were monitored throughout the study. Plasma apoA-I and PC PK profiles were similar between renal function cohorts at both doses. For CSL112 6 g mean ± SD apoA-I AUC0-last was 7670 ± 1900 and 9170 ± 2910 mg·h/dL in normal renal function and moderate RI subjects, respectively. Renal apoA-I clearance was <1% of CSL112 dose. In moderate RI, sucrose clearance was slower; however, approximately 70% was excreted within 48 hours in both renal function cohorts. No CSL112-related serious AEs or clinically significant renal or hepatic safety changes were observed. Dose adjustment of CSL112 is not required in subjects with moderate RI, supporting its further investigation in AMI patients with moderate RI.

Circulating HDL levels control hypothalamic astrogliosis via apoA-I.

Meta-inflammation of hypothalamic areas governing energy homeostasis has recently emerged as a process of potential pathophysiological relevance for the development of obesity and its metabolic sequelae. The current model suggests that diet-induced neuronal injury triggers microgliosis and astrocytosis, conditions which ultimately may induce functional impairment of hypothalamic circuits governing feeding behavior, systemic metabolism, and body weight. Epidemiological data indicate that low circulating HDL levels, besides conveying cardiovascular risk, also correlate strongly with obesity. We simulated that condition by using a genetic loss of function mouse model (apoA-I-/-) with markedly reduced HDL levels to investigate whether HDL may directly modulate hypothalamic inflammation. Astrogliosis was significantly enhanced in the hypothalami of apoA-I-/- compared with apoA-I+/+ mice and was associated with compromised mitochondrial function. apoA-I-/- mice exhibited key components of metabolic disease, like increased fat mass, fasting glucose levels, hepatic triglyceride content, and hepatic glucose output compared with apoA-I+/+ controls. Administration of reconstituted HDL (CSL-111) normalized hypothalamic inflammation and mitochondrial function markers in apoA-I-/- mice. Treatment of primary astrocytes with apoA-I resulted in enhanced mitochondrial activity, implying that circulating HDL levels are likely important for astrocyte function. HDL-based therapies may consequently avert reactive gliosis in hypothalamic astrocytes by improving mitochondrial bioenergetics and thereby offering potential treatment and prevention for obesity and metabolic disease.

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

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

CSL112 (Apolipoprotein A-I [Human]) Enhances Cholesterol Efflux Similarly in Healthy Individuals and Stable Atherosclerotic Disease Patients.

OBJECTIVE: CSL112 (apolipoprotein A-I [apoA-I; human]) is a novel formulation of apoA-I in development for reduction of early recurrent cardiovascular events after acute myocardial infarction. Cholesterol efflux capacity (CEC) is a marker of high-density lipoprotein (HDL) function that is strongly correlated with incident cardiovascular disease. Impaired CEC has been observed in patients with coronary heart disease. Here, we determined whether infused apoA-I improves CEC when administered to patients with stable atherosclerotic disease versus healthy volunteers. APPROACH AND RESULTS: Measurements of apoA-I, HDL unesterified cholesterol, HDL esterified cholesterol, pre-ß1-HDL, and CEC were determined in samples from patients with stable atherosclerotic disease before and after intravenous administration of CSL112. These measures were compared with 2 prior studies in healthy volunteers for differences in CEC at baseline and after CSL112 infusion. Patients with stable atherosclerotic disease exhibited significantly lower ATP-binding cassette transporter 1-mediated CEC at baseline (P<0.0001) despite slightly higher apoA-I levels when compared with healthy individuals (2 phase 1 studies pooled; P≤0.05), suggesting impaired HDL function. However, no differences were observed in apoA-I pharmacokinetics or in pre-ß1-HDL (P=0.5) or CEC (P=0.1) after infusion of CSL112. Similar elevation in CEC was observed in patients with low or high baseline HDL function (based on tertiles of apoA-I-normalized CEC; P=0.1242). These observations were extended and confirmed using cholesterol esterification as an additional measure. CONCLUSIONS: CSL112 shows comparable, strong, and immediate effects on CEC despite underlying cardiovascular disease. CSL112 is, therefore, a promising novel therapy for lowering the burden of atherosclerosis and reducing the risk of recurrent cardiovascular events.

Structure-function relationships in reconstituted HDL: Focus on antioxidative activity and cholesterol efflux capacity.

AIMS: High-density lipoprotein (HDL) contains multiple components that endow it with biological activities. Apolipoprotein A-I (apoA-I) and surface phospholipids contribute to these activities; however, structure-function relationships in HDL particles remain incompletely characterised. METHODS: Reconstituted HDLs (rHDLs) were prepared from apoA-I and soy phosphatidylcholine (PC) at molar ratios of 1:50, 1:100 and 1:150. Oxidative status of apoA-I was varied using controlled oxidation of Met112 residue. HDL-mediated inactivation of PC hydroperoxides (PCOOH) derived from mildly pre-oxidized low-density lipoprotein (LDL) was evaluated by HPLC with chemiluminescent detection in HDL+LDL mixtures and re-isolated LDL. Cellular cholesterol efflux was characterised in RAW264.7 macrophages. RESULTS: rHDL inactivated LDL-derived PCOOH in a dose- and time-dependent manner. The capacity of rHDL to both inactivate PCOOH and efflux cholesterol via ATP-binding cassette transporter A1 (ABCA1) increased with increasing apoA-I/PC ratio proportionally to the apoA-I content in rHDL. Controlled oxidation of apoA-I Met112 gradually decreased PCOOH-inactivating capacity of rHDL but increased ABCA1-mediated cellular cholesterol efflux. CONCLUSIONS: Increasing apoA-I content in rHDL enhanced its antioxidative activity towards oxidized LDL and cholesterol efflux capacity via ABCA1, whereas oxidation of apoA-I Met112 decreased the antioxidative activity but increased the cholesterol efflux. These findings provide important considerations in the design of future HDL therapeutics. Non-standard abbreviations and acronyms: AAPH, 2,2'-azobis(-amidinopropane) dihydrochloride; ABCA1, ATP-binding cassette transporter A1; apoA-I, apolipoprotein A-I; BHT, butylated hydroxytoluene; CV, cardiovascular; EDTA, ethylenediaminetetraacetic acid; HDL-C, high-density lipoprotein cholesterol; LOOH, lipid hydroperoxides; Met(O), methionine sulfoxide; Met112, methionine 112 residue; Met86, methionine 86 residue; oxLDL, oxidized low-density lipoprotein; PBS, phosphate-buffered saline; PC, phosphatidylcholine; PL, phospholipid; PCOOH, phosphatidylcholine hydroperoxide; PLOOH, phospholipid hydroperoxide.

A Consensus Definitive Classification of Scavenger Receptors and Their Roles in Health and Disease.

Scavenger receptors constitute a large family of proteins that are structurally diverse and participate in a wide range of biological functions. These receptors are expressed predominantly by myeloid cells and recognize a diverse variety of ligands including endogenous and modified host-derived molecules and microbial pathogens. There are currently eight classes of scavenger receptors, many of which have multiple names, leading to inconsistencies and confusion in the literature. To address this problem, a workshop was organized by the United States National Institute of Allergy and Infectious Diseases, National Institutes of Health, to help develop a clear definition of scavenger receptors and a standardized nomenclature based on that definition. Fifteen experts in the scavenger receptor field attended the workshop and, after extensive discussion, reached a consensus regarding the definition of scavenger receptors and a proposed scavenger receptor nomenclature. Scavenger receptors were defined as cell surface receptors that typically bind multiple ligands and promote the removal of nonself or altered-self targets. They often function by mechanisms that include endocytosis, phagocytosis, adhesion, and signaling that ultimately lead to the elimination of degraded or harmful substances. Based on this definition, nomenclature and classification of these receptors into 10 classes were proposed. This classification was discussed at three national meetings and input from participants at these meetings was requested. The following manuscript is a consensus statement that combines the recommendations of the initial workshop and incorporates the input received from the participants at the three national meetings.

Enhanced HDL Functionality in Small HDL Species Produced Upon Remodeling of HDL by Reconstituted HDL, CSL112: Effects on Cholesterol Efflux, Anti-Inflammatory and Antioxidative Activity.

RATIONALE: CSL112, human apolipoprotein A-I (apoA-I) reconstituted with phosphatidylcholine, is known to cause a dramatic rise in small high-density lipoprotein (HDL). OBJECTIVE: To explore the mechanisms by which the formation of small HDL particles is induced by CSL112. METHODS AND RESULTS: Infusion of CSL112 into humans caused elevation of 2 small diameter HDL fractions and 1 large diameter fraction. Ex vivo studies showed that this remodeling does not depend on lipid transfer proteins or lipases. Rather, interaction of CSL112 with purified HDL spontaneously gave rise to 3 HDL species: a large, spherical species composed of apoA-I from native HDL and CSL112; a small, disc-shaped species composed of apoA-I from CSL112, but smaller because of the loss of phospholipids; and the smallest species, lipid-poor apoA-I composed of apoA-I from HDL and CSL112. Time-course studies suggest that remodeling occurs by an initial fusion of CSL112 with HDL and subsequent fission leading to the smaller forms. Functional studies showed that ATP-binding cassette transporter 1-dependent cholesterol efflux and anti-inflammatory effects in whole blood were carried by the 2 small species with little activity in the large species. In contrast, the ability to inactivate lipid hydroperoxides in oxidized low-density lipoprotein was carried predominantly by the 2 largest species and was low in lipid-poor apoA-I. CONCLUSIONS: We have described a mechanism for the formation of small, highly functional HDL species involving spontaneous fusion of discoidal HDL with spherical HDL and subsequent fission. Similar remodeling is likely to occur during the life cycle of apoA-I in vivo.

Cyclodextrin promotes atherosclerosis regression via macrophage reprogramming.

Atherosclerosis is an inflammatory disease linked to elevated blood cholesterol concentrations. Despite ongoing advances in the prevention and treatment of atherosclerosis, cardiovascular disease remains the leading cause of death worldwide. Continuous retention of apolipoprotein B-containing lipoproteins in the subendothelial space causes a local overabundance of free cholesterol. Because cholesterol accumulation and deposition of cholesterol crystals (CCs) trigger a complex inflammatory response, we tested the efficacy of the cyclic oligosaccharide 2-hydroxypropyl-ß-cyclodextrin (CD), a compound that increases cholesterol solubility in preventing and reversing atherosclerosis. We showed that CD treatment of murine atherosclerosis reduced atherosclerotic plaque size and CC load and promoted plaque regression even with a continued cholesterol-rich diet. Mechanistically, CD increased oxysterol production in both macrophages and human atherosclerotic plaques and promoted liver X receptor (LXR)-mediated transcriptional reprogramming to improve cholesterol efflux and exert anti-inflammatory effects. In vivo, this CD-mediated LXR agonism was required for the antiatherosclerotic and anti-inflammatory effects of CD as well as for augmented reverse cholesterol transport. Because CD treatment in humans is safe and CD beneficially affects key mechanisms of atherogenesis, it may therefore be used clinically to prevent or treat human atherosclerosis.

Reconstituted high-density lipoproteins acutely reduce soluble brain Aß levels in symptomatic APP/PS1 mice.

Many lines of evidence suggest a protective role for high-density lipoprotein (HDL) and its major apolipoprotein (apo)A-I in Alzheimer's Disease (AD). HDL/apoA-I particles are produced by the liver and intestine and, in addition to removing excess cholesterol from the body, are increasingly recognized to have vasoprotective functions. Here we tested the ability of reconstituted HDL (rHDL) consisting of human apoA-I reconstituted with soy phosphatidylcholine for its ability to lower amyloid beta (Aß) levels in symptomatic APP/PS1 mice, a well-characterized preclinical model of amyloidosis. Animals were treated intravenously either with four weekly doses (chronic study) or a single dose of 60mg/kg of rHDL (acute study). The major finding of our acute study is that soluble brain Aß40 and Aß42 levels were significantly reduced within 24h of a single dose of rHDL. By contrast, no changes were observed in our chronic study with respect to soluble or deposited Aß levels in animals assessed 7days after the final weekly dose of rHDL, suggesting that beneficial effects diminish as rHDL is cleared from the body. Further, rHDL-treated animals showed no change in amyloid burden, cerebrospinal fluid (CSF) Aß levels, neuroinflammation, or endothelial activation in the chronic study, suggesting that the pathology-modifying effects of rHDL may indeed be acute and may be specific to the soluble Aß pool. That systemic administration of rHDL can acutely modify brain Aß levels provides support for further investigation of the therapeutic potential of apoA-I-based agents for AD. This article is part of a Special Issue entitled: Vascular Contributions to Cognitive Impairment and Dementia edited by M. Paul Murphy, Roderick A. Corriveau and Donna M. Wilcock.

Reconstituted high-density lipoprotein can elevate plasma alanine aminotransferase by transient depletion of hepatic cholesterol: role of the phospholipid component.

Human apolipoprotein A-I preparations reconstituted with phospholipids (reconstituted high-density lipoprotein [HDL]) have been used in a large number of animal and human studies to investigate the physiological role of apolipoprotein A-I. Several of these studies observed that intravenous infusion of reconstituted HDL might cause transient elevations in plasma levels of hepatic enzymes. Here we describe the mechanism of this enzyme release. Observations from several animal models and in vitro studies suggest that the extent of hepatic transaminase release (alanine aminotransferase [ALT]) correlates with the movement of hepatic cholesterol into the blood after infusion. Both the amount of ALT release and cholesterol movement were dependent on the amount and type of phospholipid present in the reconstituted HDL. As cholesterol is known to dissolve readily in phospholipid, an HDL preparation was loaded with cholesterol before infusion into rats to assess the role of diffusion of cholesterol out of the liver and into the reconstituted HDL. Cholesterol-loaded HDL failed to withdraw cholesterol from tissues and subsequently failed to cause ALT release. To investigate further the role of cholesterol diffusion, we employed mice deficient in SR-BI, a transporter that facilitates spontaneous movement of cholesterol between cell membranes and HDL. These mice showed substantially lower movement of cholesterol into the blood and markedly lower ALT release. We conclude that initial depletion of hepatic cholesterol initiates transient ALT release in response to infusion of reconstituted HDL. This effect may be controlled by appropriate choice of the type and amount of phospholipid in reconstituted HDL. Copyright © 2015 John Wiley & Sons, Ltd.

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

BACKGROUND: CSL112 is a new formulation of human apolipoprotein A-I (apoA-I) being developed to reduce cardiovascular events following acute coronary syndrome. This phase 2a, randomized, double-blind, multicenter, dose-ranging trial represents the first clinical investigation to assess the safety and pharmacokinetics/pharmacodynamics of a CSL112 infusion among patients with stable atherosclerotic disease. METHODS AND RESULTS: Patients were randomized to single ascending doses of CSL112 (1.7, 3.4, or 6.8 g) or placebo, administered over a 2-hour period. Primary safety assessments consisted of alanine aminotransferase or aspartate aminotransferase elevations >3× upper limits of normal and study drug-related adverse events. Pharmacokinetic/pharmacodynamic assessments included apoA-I plasma concentration and measures of the ability of serum to promote cholesterol efflux from cells ex vivo. Of 45 patients randomized, 7, 12, and 14 received 1.7-, 3.4-, and 6.8-g CSL112, respectively, and 11 received placebo. There were no clinically significant elevations (>3× upper limit of normal) in alanine aminotransferase or aspartate aminotransferase. Adverse events were nonserious and mild and occurred in 5 (71%), 5 (41%), and 6 (43%) patients in the CSL112 1.7-, 3.4-, and 6.8-g groups, respectively, compared with 3 (27%) placebo patients. The imbalance in adverse events was attributable to vessel puncture/infusion-site bruising. CSL112 resulted in rapid (T(max)≈2 hours) and dose-dependent increases in apoA-I (145% increase in the 6.8-g group) and total cholesterol efflux (up to 3.1-fold higher than placebo) (P<0.001). CONCLUSIONS: CSL112 infusion was well tolerated in patients with stable atherosclerotic disease. CSL112 immediately raised apoA-I levels and caused a rapid and marked increase in the capacity of serum to efflux cholesterol. This potential novel approach for the treatment of atherosclerosis warrants further investigation. CLINICAL TRIAL REGISTRATION: URL: http://www.ClinicalTrials.gov. Unique identifier: NCT01499420.