Circulating oxidized LDL: determinants and association with brachial flow-mediated dilation

Area of Science:

• Cardiovascular Research
• Biochemistry
• Clinical Medicine

Background:

• Circulating oxidized LDL (oxLDL) is linked to cardiovascular risk, but its independent contribution is unclear due to strong correlations with LDL-cholesterol (LDL-c) and apolipoprotein-B100 (apoB100).
• Disentangling the specific roles of oxLDL, LDL-c, and apoB100 in atherosclerosis is crucial for accurate risk assessment.

Purpose of the Study:

• To investigate the determinants of oxLDL levels.
• To explore the relationship between oxLDL and brachial artery flow-mediated dilation (FMD), a functional measure of atherosclerosis.
• To determine if oxLDL/LDL-c and oxLDL/apoB100 ratios offer greater insight into cardiovascular risk than individual markers.

Main Methods:

• Cross-sectional analysis of 624 participants (aged 50-87) from a population-based cohort study.
• Measurement of plasma oxLDL, LDL-c, apoB100, and brachial artery FMD.
• Statistical analysis to identify determinants of oxLDL and its association with FMD, adjusting for relevant covariates.

Main Results:

• OxLDL strongly correlated with apoB100 (r=0.82) and LDL-c (r=0.67).
• Independent determinants of oxLDL included sex, HDL-cholesterol, and LDL particle size.
• LDL-c and apoB100 levels were not significantly associated with FMD.
• The oxLDL/apoB100 ratio showed a significant negative association with FMD (P=0.017) after adjustments, while the oxLDL/LDL-c ratio showed a weaker association (P=0.062), and oxLDL alone showed no association (P=0.27).

Conclusions:

• The oxLDL/apoB100 ratio, and to a lesser extent the oxLDL/LDL-c ratio, are associated with a functional measure of atherosclerosis (FMD), unlike oxLDL levels alone.
• Correcting oxLDL for LDL particle number (apoB100) may enhance the clinical utility of oxLDL measurements in assessing cardiovascular risk.