Differential stability of high-density lipoprotein subclasses: effects of particle size and protein composition

Area of Science:

• Cardiovascular Science
• Lipid Metabolism
• Protein Biochemistry

Background:

• High-density lipoproteins (HDL) are crucial for cholesterol removal and preventing atherosclerosis.
• HDL comprises heterogeneous subclasses with distinct metabolic properties, including HDL(2) (large) and HDL(3) (small).
• Apolipoprotein A-I (apoA-I) is cardioprotective, while the role of apolipoprotein A-II (apoA-II) in HDL function remains debated.

Purpose of the Study:

• To investigate the kinetic stability of human HDL subclasses.
• To determine the influence of particle size and protein composition (apoA-I vs. apoA-I/A-II) on HDL stability and remodeling.
• To reconcile conflicting reports on the role of apoA-II in HDL remodeling.

Main Methods:

• Performed the first kinetic stability study on human HDL subclasses.
• Compared the stability of HDL(A-I) and HDL(A-I/A-II) subclasses.
• Analyzed the impact of particle diameter on HDL stability.

Main Results:

• HDL stability decreases as particle diameter increases, potentially facilitating cholesterol ester uptake by larger HDL(2) particles.
• Size-matched HDL(A-I/A-II) particles exhibited comparable or slightly lower stability than HDL(A-I) particles.
• Findings suggest apoA-II does not significantly destabilize HDL, contrary to some previous hypotheses.

Conclusions:

• HDL particle size is a key determinant of plasma HDL stability.
• The protein composition, specifically the presence of apoA-II, has a less pronounced effect on HDL stability than previously thought.
• These results clarify the roles of particle size and protein composition in HDL remodeling and reconcile existing literature.