Very-Low-Density Lipoproteins Quantity but Not Composition Is Altered in Normotriglyceridemic Subjects with Elevated Lipoprotein (a) Level

TL;DR

In people with normal triglyceride levels but high Lp(a), VLDL particles are more numerous but not chemically different, which may still pose cardiovascular risks.

Contribution

This study reveals that elevated Lp(a) in normotriglyceridemic individuals increases VLDL particle number without altering composition.

Findings

Individuals with Lp(a) ≥ 30 mg/dL had significantly higher VLDL concentrations of triglycerides, cholesterol, and apolipoproteins.

VLDL particle composition remained unchanged, suggesting increased particle number rather than altered composition.

Redistribution of lipids and apolipoproteins toward VLDL may contribute to residual cardiovascular risk.

Abstract

Cardiovascular disease (CVD) is influenced by disturbances in lipoprotein composition and metabolism, including triglyceride-rich lipoproteins (TRLs) and elevated lipoprotein (a) (Lp(a)). While interactions between Lp(a) and very-low-density lipoproteins (VLDL) have been studied in hypertriglyceridemic and CVD populations, data in normotriglyceridemic individuals without CV events are limited. Seventy normotriglyceridemic adults with triglycerides < 150 mg/dL and no CV events were enrolled and divided into two groups based on Lp(a) concentration: <30 mg/dL and ≥30 mg/dL. VLDL was isolated by ultracentrifugation, and concentrations of Lp(a), lipids (triglycerides, cholesterol), and apolipoproteins (apo B, apo C-II, apo C-III, apo E) were measured in serum and VLDL. Serum lipid and apolipoprotein concentrations did not differ between the groups. Individuals with Lp(a) ≥ 30 mg/dL had significantly higher VLDL concentrations of triglycerides (+71%), cholesterol (+54%), apo B (+28%), apo C-II (+36%), and apo C-III (+33%). Ratios of lipids and apolipoproteins to apo B indicated unchanged VLDL particle composition, suggesting that differences reflected increased particle number rather than altered composition. In normotriglyceridemic subjects with Lp(a) ≥ 30 mg/dL, VLDL particles are more abundant but compositionally unchanged. Redistribution of lipids and apolipoproteins toward VLDL may contribute to VLDL residual cardiovascular risk, underscoring the need for further studies on VLDL-Lp(a) interactions.

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