(P26-001-23) HDL Subtypes From 36-Hour Fasted Plasma Reveals Differences in Particle Size, Composition, and Efflux Capacity, Using Novel Application of UC-SEC With Optical Detectors

Objectives: High density lipoprotein (HDL) are complex nanoparticles most notably known for its ability to modulate cellular cholesterol concentration. HDL cholesterol have been linked with longevity and protection against chronic diseases such as Alzheimer’s Disease and Cardiovascular Disease, however it is still unclear how HDL particles are dysregulated in different disease states and how to effectively intervene to improve HDL-related outcomes. Here, we demonstrate the importance of analyzing changes in HDL’s size distribution, count, and composition per particle. Our objective is to develop a method that concurrently isolates and measures particle concentration, composition, and size distribution of high-density lipoproteins (HDL).

Methods: Our sample subject includes 10 male and 10 female participants who fasted for 36 hours. Plasma samples were obtained from 4 timepoints including following a standard overnight fast, in the fed state (2h postprandial), after a 36h water-only fast, and in the re-fed state (2h postprandial). Using optimized sequential ultracentrifugation (UC) followed by size exclusion chromatography (SEC) method, lipoproteins were isolated to obtain three HDL particle subtypes between densities 1.006 g/mL to 1.21 g/mL and one HDL particle subtype between densities 1.21 g/mL to 1.25 g/mL. Particles were then analyzed using multi-in-line optical detectors – Multi Angle Light Scattering, Dynamic Light Scattering, Diode Array Detector, and Refractive Index Detector (MALS/DLS/DAD/RI)- to measure particle size distribution, composition, and concentration. Cholesterol efflux capacities (CEC) of four HDL subtypes were measured and dosed by particle concentration to evaluate differences in function per particle.

Results: Our findings show that HDL CEC particle function is differentiated by size distribution, and in different physiological conditions.

Conclusions: This method allows further separation of HDL subtypes by size and by density into four HDL subtypes, and enables the functional and compositional analysis of HDL on a per-particle basis. These advances may lead to the discovery of novel disease biomarkers, and new HDL-based therapeutic targets for disease prevention and treatment.

Funding Sources: NIH R01 Method development grant