Improved plasma cholesterol efflux capacity from human macrophages in patients with hyperalphalipoproteinemia

Area of Science:

• Lipid metabolism and cardiovascular disease research.
• Atherosclerosis and high-density lipoprotein (HDL) function.

Background:

• Cholesteryl ester transfer protein (CETP) and hepatic lipase (HL) deficiencies increase HDL-C levels.
• The atheroprotective role of this phenotype, specifically HDL's cholesterol efflux capacity from macrophages, requires investigation.

Purpose of the Study:

• To determine the cholesterol efflux capacity of HDL particles in patients with high HDL-C (HALP) due to CETP or LIPC gene defects.
• To assess if HDL from these patients can effectively remove cholesterol from human macrophages.

Main Methods:

• Cholesterol efflux was measured from human THP-1 macrophages.
• Efflux was assessed using total plasma or isolated HDL subfractions from patients with HALP.
• Genetic defects in CETP or LIPC genes were identified in the patient cohort.

Main Results:

• HALP is linked to increased cholesterol efflux capacity from human macrophages.
• This enhancement is attributed to stimulated SR-BI and ABCA1 pathways.
• Quantitative increases in HDL2 and improved intrinsic capacity of HDL3 subspecies contribute to the effect.

Conclusions:

• HDL particles from HALP patients with CETP or LIPC gene defects are functional.
• These HDL particles efficiently stimulate cholesterol efflux from human macrophages, indicating a potential atheroprotective mechanism.