Abstract 626: The ABCA1 Agonist Peptides CS-6253 and ATI-5261 Replicate ApoA-I Function and Generate nHDL Particles that Are Remodeled and Maturated Within the Plasma Compartment, Resulting in Efficient Cholesterol SR-BI Delivery to Hepatic Cells
Novel apolipoprotein (apo) mimetic peptides are potent mediators of ABCA1-mediated cholesterol efflux, mimicking native apoA-I. We investigated CS-6253 (CS) and ATI-5261 (ATI) in their ability to promote lipid transfer between nascent (n)HDL particles and plasma lipoproteins and examined cholesterol influx from remodelled HDL-like particles to hepatic cells through the SR-BI receptor. nHDL-like lipoproteins nHDL-CS and nHDL-ATI were generated by incubating CS or ATI in the presence of BHK cells expressing ABCA1 labelled with 3[H]cholesterol and 3[H] choline; native apoA-I was used as control. These nHDL particles were incubated with plasma at 37°C. Both CS and ATI increased LCAT activity significantly, although were approximately 50% less efficient than nHDL-apoA-I (fractional esterification rate (FER) =22.32±0.86%/h; vs nHDL-CS and nHDL-ATI; FER=11.40±0.045%/h; p<0.05). The majority of 3[H]cholesterol from nHDL mimetics was esterified by LCAT, resulting in an increase in α1-migrating HDL-like particles in plasma (as shown by 2D-PAGGE). The ability of nHDL mimetics to transfer 3[H]-phosphatidyl choline to plasma apoB-containing lipoproteins is (76±20%) in HDL-apoA-I, (38±0.5%) in nHDL-ATI and (54±13%) in nHDL-CS. These data show that nHDL mimetics are actively remodelled in the presence of plasma lipoproteins. We then investigated cholesterol delivery from HDL-CS and HDL-ATI mimetic to hepatic tissue via SR-BI using Fu5AH cells, having HDL-apoA-I as control. Kinetic parameters for SR-BI-mediated cholesterol influx are as follows: HDL-CS (Km= 0.30±0.05 ug/ml; p<0.05) efficient as HDL apoA-I at promoting cholesterol uptake into Fu5AH cells (Km= 0.37±0.13 ug/ml), while HDL-ATI was least efficient (Km= 1.03±0.20 ug/ml). The inhibition of SR-BI selective uptake with BLT-1 affected the uptake of cholesterol from apoB precipitated plasma containing either HDL-CS, HDL-ATI or apoA-I. Here we present an in-vitro model of nHDL-CS and nHDL-ATI that actively undergo remodelling and maturation in plasma and replicate the function of apoA-I. These mature HDL mimetics generated from ABCA1 agonist peptides deliver cholesterol efficiently to hepatocytes specifically through the SR-BI receptor.
Author Disclosures: A. Hafiane: None. J. Bielicki: None. J. Johansson: None. J. Genest: None.
- © 2014 by American Heart Association, Inc.