Abstract 238: Incubation of MDCO216 With Human Serum or Plasma Potentiates ABCA1-Mediated Cholesterol Efflux Capacity, Increases Prebeta-1 HDL and Causes a Shift From Small to Large Alpha HDL Particles

MDCO216 is a complex of dimeric apoA-IMilano and POPC, shown to reduce atherosclerotic plaque burden. Here we studied the effect of incubation of human plasma or serum with MDCO216 on cholesterol efflux capacity from J774 cells, on prebeta-1 HDL and various HDL subfractions. At clinically relevant concentrations MDCO216 by itself markedly stimulates global and ABCA1-mediated cholesterol efflux. When incubated with human serum a time-dependent synergistic increase of the ABCA1 mediated efflux capacity is observed. Using the Sekisui ELISA for prebeta-1 HDL, MDCO216 itself is poorly detected. Prebeta-1 HDL is rapidly lost when human plasma alone is incubated at 37oC. However, incubation of human plasma with MDCO216 at 37oC causes a robust generation of new prebeta-1 HDL. 2D-Electrophoresis followed by immunoblotting with a general apoA-I antibody that also detects apoA-IM confirms the increase in prebeta-1 HDL (having a different mobility than pure MDCO216 particles), and shows a concomitant disappearance of alpha-3 HDL, alpha-4 HDL and MDCO216, and an increase in alpha-1 and alpha-2 HDL. NMR analysis of plasma incubated with MDCO216 at 47oC confirms very rapid disappearance of small HDL and increase of medium and large HDL particles. In conclusion, incubation of human plasma or serum with MDCO216 strongly enhances ABCA1-mediated cholesterol efflux capacity, causes a strong increase of prebeta-1 HDL and drastically changes HDL subfraction distribution, consistent with anti-atherosclerotic activity.