Abstract 222: HDL-ApoA-I Exchange Rate is Inversely Correlated With Coronary Artery Disease Stability
Objective: The exchange of apolipoprotein A-I between lipid-associated and lipid-free states is a key step in reverse cholesterol transport and is representative of HDL’s functional status. Reduced HDL-apoA-I exchange (HAE) is associated with the presence of cardiovascular disease. To build on this observation, we investigated the hypothesis that HAE in a coronary artery disease-identified patient decreases with increased coronary artery disease instability.
Method: HAE was measured by electron paramagnetic resonance spectroscopy (EPR), wherein nitroxide-labeled lipid-free apoA-I is introduced into apolipoprotein B-depleted plasma, incubated at 37°C and measured. When added to plasma, the nitroxide-labeled apoA-I specifically interacts with HDL and displaces resident apoA-I. The EPR spectrum reports the population of lipid-bound, spin labeled apoA-I, which is directly proportional to the amount of resident apoA-I displaced. The relative level of apoA-I displaced is representative of the plasticity of HDL and its ability to make lipid-poor apoA-I available for ABCA1-mediated cholesterol efflux. We measured HAE in the plasma of three groups: stable coronary artery disease (n=22), 3 months following acute coronary syndrome (n=19), and a control group with no history of coronary artery disease (n=15).
Results: HAE was significantly lower in both the stable coronary artery disease and acute coronary syndrome groups, compared to the control group (P<0.001 and, P<0.0001, respectively). Remarkably, the ACS subjects also had significantly lower HAE compared to those with stable CAD (P<0.01). By comparing HAE to apoA-I and HDL-C levels, we observed that stable CAD and ACS subjects have lower HAE per milligram/deciliter of apoA-I, consistent with a qualitative deficiency in their apoA-I.
Conclusions: HAE activity is a by-product of apoA-I qualitative status, which is inversely correlated with coronary artery disease stability.
Author Disclosures: M.S. Borja: Research Grant; Significant; MSB received funding from an AHA Western States Affiliate postdoctoral fellowship 14POST18330018 for this work.. Y. He: None. J. Genest: None. M.N. Oda: Ownership Interest; Significant; MNO owns a significant stake in Seer BioLogics, Inc., which could stand to benefit from the research described here. MNO is a cofounder and board member of the company., MNO filed a patent describing this assay through Children's Hospital Oakland in 2011..
This research has received full or partial funding support from the American Heart Association.
- © 2014 by American Heart Association, Inc.