Abstract 15370: Mechanism of High Density Lipoprotein Remodeling Induced by CSL112
Introduction: CSL112 is apolipoprotein A-I (apoA[[Unable to Display Character: ‐]]I) purified from human plasma and reconstituted with phosphatidylcholine to form lipoprotein particles suitable for infusion. This formulation is designed to optimize cholesterol efflux by the ATP-binding cassette A1 (ABCA1) transporter present in macrophages of atherosclerotic plaque. We have recently demonstrated that infusion of CSL112 into humans dramatically raises the ability of plasma to mediate ABCA1-dependent cholesterol efflux and this strong elevation was accompanied by a very large (>30-fold) increase in plasma levels of lipid-poor apoA-I (Pre-Beta1 high density lipoprotein (HDL)), the preferred substrate for ABCA1. In this study we investigated the origin of lipid-poor apoA-I produced upon incubation of CSL112 with human plasma ex vivo.
Methods and Results: CSL112 was incubated with human plasma or purified HDL for 1 h at 37°C. HDL particle size distribution was assessed by native gel electrophoresis followed by western blotting.
A robust formation of lipid-poor apoA-I was observed upon incubation of CSL112 with whole plasma or native HDL, but not with plasma depleted of lipoproteins. Products of the remodeling purified by ultracentrifugation showed much higher capacity to efflux cholesterol via ABCA1 compared to the original CSL112 and HDL. These findings demonstrate that native HDL is necessary and sufficient for both remodeling of CSL112 and elevation of cholesterol efflux capacity of plasma. Upon incubation of fluorescently labeled CSL112 and biotinylated HDL, the resulting lipid-poor apoA-I incorporated both labels and could be fully precipitated on streptavidin beads indicating that it is dimeric and contained apoA-I derived from both HDL and CSL112.
Conclusion: Our results suggest that CSL112 fuses with HDL in plasma with subsequent release of lipid-poor apoA-I. Observations on the time course and size distribution of HDL species from patients infused with CSL112 suggest the same sequence occurs in vivo. This study provides a biochemical basis for the elevation of cholesterol efflux and lipid-poor apoA-I observed upon infusion of CSL112 into human subjects. These properties make CSL112 a promising approach for rapidly removing cholesterol from atherosclerotic plaque.
Author Disclosures: S. Didichenko: Employment; Significant; CSL Behring. A.V. Navdaev: Employment; Significant; CSL Behring. M.O. Spycher: Employment; Significant; CSL Behring. A. Gille: Employment; Significant; CSL Limited. Ownership Interest; Significant; CSL Limited. S.D. Wright: Employment; Significant; CSL Behring. Ownership Interest; Significant; CSL Behring.
- © 2014 by American Heart Association, Inc.