Relationship between low-density lipoprotein size and apolipoprotein A-I-containing particles: the ECTIM study

Area of Science:

• Lipid metabolism and cardiovascular disease research.

Background:

• Small dense low-density lipoproteins (LDLs) are more prevalent in patients with coronary heart disease (CHD).
• Small LDL size is associated with a pro-atherogenic lipid profile, including elevated triglycerides and reduced high-density lipoprotein (HDL)-cholesterol.
• Human HDL particles vary, with some containing apolipoprotein (apo) A-I and apoA-II (LpA-I:A-II), while others contain apoA-I only (LpA-I).

Purpose of the Study:

• To investigate the relationship between LDL particle size and HDL parameters, specifically LpA-I and LpA-I:A-II levels.
• To determine if HDL metabolism influences LDL size independently of triglyceride levels.

Main Methods:

• Non-denaturing gradient-gel electrophoresis was used to measure LDL size in 408 healthy control subjects.
• Levels of HDL-cholesterol, apoA-I, apoA-II, LpA-I, and LpA-I:A-II were quantified.
• Statistical analyses, including correlation and multivariate analysis, were performed.

Main Results:

• LDL size positively correlated with HDL-cholesterol, apoA-I, and LpA-I.
• A progressive increase in apoA-I and LpA-I was observed from the smallest to the largest LDL size quintiles.
• Multivariate analysis indicated that HDL-cholesterol, apoA-I, and LpA-I are determinants of LDL size, independent of triglycerides.

Conclusions:

• LDL size is associated with HDL metabolism, specifically with LpA-I levels, independent of triglyceride levels.
• A combination of small LDLs and low LpA-I concentrations may contribute to the high-risk profile observed in individuals with small LDLs.
• These findings highlight the complex interplay between different lipoprotein subclasses in cardiovascular risk assessment.