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.

Apo AI Nanoparticles Delivered Post Myocardial Infarction Moderate Inflammation.

RATIONALE: Decades of research have examined immune-modulatory strategies to protect the heart after an acute myocardial infarction and prevent progression to heart failure but have failed to translate to clinical benefit. OBJECTIVE: To determine anti-inflammatory actions of n-apo AI (Apo AI nanoparticles) that contribute to cardiac tissue recovery after myocardial infarction. METHODS AND RESULTS: Using a preclinical mouse model of myocardial infarction, we demonstrate that a single intravenous bolus of n-apo AI (CSL111, 80 mg/kg) delivered immediately after reperfusion reduced the systemic and cardiac inflammatory response. N-apo AI treatment lowered the number of circulating leukocytes by 30±7% and their recruitment into the ischemic heart by 25±10% (all P<5.0×10-2). This was associated with a reduction in plasma levels of the clinical biomarker of cardiac injury, cardiac troponin-I, by 52±17% (P=1.01×10-2). N-apo AI reduced the cardiac expression of chemokines that attract neutrophils and monocytes by 60% to 80% and lowered surface expression of integrin CD11b on monocytes by 20±5% (all P<5.0×10-2). Fluorescently labeled n-apo AI entered the infarct and peri-infarct regions and colocalized with cardiomyocytes undergoing apoptosis and with leukocytes. We further demonstrate that n-apo AI binds to neutrophils and monocytes, with preferential binding to the proinflammatory monocyte subtype and partially via SR-BI (scavenger receptor BI). In patients with type 2 diabetes, we also observed that intravenous infusion of the same n-apo AI (CSL111, 80 mg/kg) similarly reduced the level of circulating leukocytes by 12±5% (all P<5.0×10-2). CONCLUSIONS: A single intravenous bolus of n-apo AI delivered immediately post-myocardial infarction reduced the systemic and cardiac inflammatory response through direct actions on both the ischemic myocardium and leukocytes. These data highlight the anti-inflammatory effects of n-apo AI and provide preclinical support for investigation of its use for management of acute coronary syndromes in the setting of primary percutaneous coronary interventions.

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.

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.