title: Incubation of MDCO-216 (ApoA-IMilano/POPC) with Human Serum Potentiates ABCA1-Mediated Cholesterol Efflux Capacity, Generates New Prebeta-1 HDL, and Causes an Increase in HDL Size.
abstract: MDCO-216 is a complex of dimeric ApoA-IMilano and palmitoyl oleoyl phosphatidylcholine (POPC), previously shown to reduce atherosclerotic plaque burden. Here we studied the effect of incubation of human plasma or serum with MDCO-216 on cholesterol efflux capacity from J774 cells, on prebeta-1 high density lipoprotein (prebeta-1 HDL) and on HDL size assessed by proton nuclear magnetic resonance ((1)H-NMR). MDCO-216 incubated in buffer containing 4% human serum albumin stimulated both ABCA1-mediated efflux and ABCA1-independent cholesterol efflux from J774 macrophages. When incubated with human serum a dose- and time-dependent synergistic increase of the ABCA1-mediated efflux capacity were observed. Using a commercially available ELISA for prebeta-1 HDL, MDCO-216 as such was poorly detected (12-15% of nominal amount of protein). Prebeta-1 HDL was rapidly lost when human plasma alone is incubated at 37°C. In contrast, incubation of human plasma with MDCO-216 at 37°C produced a large amount of new prebeta-1 HDL. Native 2D electrophoresis followed by immunoblotting with an apoA-I antibody, which also detects ApoA-I Milano, confirmed the increase in prebeta-1 HDL upon incubation at 37°C. With the increase of prebeta-1 HDL, the concomitant disappearance of the small alpha-3 and alpha-4 HDL and MDCO-216 and an increase in the large alpha-1 and alpha-2 HDL were observed. Immunoblotting with Mab 17F3 specific for ApoA-I Milano showed the appearance of ApoA-I Milano in alpha-1 and alpha-2, but not in prebeta-1 HDL. (1)H-NMR analysis of plasma incubated with MDCO-216 confirmed rapid disappearance of small-sized HDL particles and increase of medium- and large-sized HDL particles accompanied with a decrease in total HDL particle number. In conclusion, incubation of human plasma or serum with MDCO-216 strongly enhanced ABCA1-mediated cholesterol efflux, caused a strong increase of prebeta-1 HDL, and drastically changed the distribution of HDL subpopulations. Overall, the results are in line with the hypothesis that MDCO-216 fuses with small alpha-migrating HDL particles forming larger particles containing both apoA-I WT and ApoA-I Milano, meanwhile liberating the endogenous wild-type apoA-I which enriches prebeta-1 HDL subpopulation.
authors.affiliation: The Medicines Company (Schweiz) GmbH, Talstrasse 59, 8002 Zürich, Switzerland.
authors.forename: Herman J
authors.identifier: 0000-0002-9915-5322
authors.initials: HJ
authors.lastname: Kempen
authors.affiliation: Pacific Biomarkers LLC, 645 Elliott Avenue West, Suite 300, Seattle, WA 98119, USA.
authors.forename: Dorota B
authors.initials: DB
authors.lastname: Schranz
authors.affiliation: Lipid Metabolism Laboratory, Tufts University, 711 Washington Street, Boston, MA 02111, USA.
authors.forename: Bela F
authors.initials: BF
authors.lastname: Asztalos
authors.affiliation: Liposcience LLC, 2500 Sumner Boulevard, Raleigh, NC 27616, USA.
authors.forename: James
authors.initials: J
authors.lastname: Otvos
authors.affiliation: Liposcience LLC, 2500 Sumner Boulevard, Raleigh, NC 27616, USA.
authors.forename: Elias
authors.identifier: 0000-0002-4513-6484
authors.initials: E
authors.lastname: Jeyarajah
authors.affiliation: Vascular Strategies LLC, 5110 Campus Drive, Suite 150, Plymouth Meeting, PA 19462, USA.
authors.forename: Denise
authors.initials: D
authors.lastname: Drazul-Schrader
authors.affiliation: Vascular Strategies LLC, 5110 Campus Drive, Suite 150, Plymouth Meeting, PA 19462, USA.
authors.forename: Heidi L
authors.identifier: 0000-0002-0706-7422
authors.initials: HL
authors.lastname: Collins
authors.affiliation: Vascular Strategies LLC, 5110 Campus Drive, Suite 150, Plymouth Meeting, PA 19462, USA.
authors.forename: Steven J
authors.identifier: 0000-0003-2105-5759
authors.initials: SJ
authors.lastname: Adelman
authors.affiliation: The Medicines Company (Schweiz) GmbH, Talstrasse 59, 8002 Zürich, Switzerland.
authors.forename: Peter L J
authors.initials: PL
authors.lastname: Wijngaard