Plasma triglyceride determines structure-composition in low and high density lipoproteins

Area of Science:

• Lipid metabolism and cardiovascular disease
• Atherosclerosis research
• Lipoprotein structure and function

Background:

• Hypertriglyceridemia is linked to premature atherosclerosis.
• The direct role of triglyceride molecules in this association is unclear.
• Understanding lipoprotein alterations in hypertriglyceridemia is crucial.

Purpose of the Study:

• To investigate the impact of elevated plasma triglyceride-rich lipoproteins on LDL and HDL composition and structure.
• To elucidate the mechanisms behind lipoprotein modification in hypertriglyceridemia.

Main Methods:

• Analysis of lipoprotein composition (cholesterol esters, triglycerides, phospholipids, protein) in relation to plasma triglyceride levels.
• Assay of triglyceride/cholesterol ester ratios in LDL and HDL.
• Correlation analysis to determine relationships between lipoprotein components and plasma triglyceride concentrations.

Main Results:

• Increasing triglyceridemia caused significant depletion of cholesterol esters and enrichment of triglycerides in the core of LDL and HDL.
• Lipoprotein surface domains showed depletion of phospholipids and free cholesterol, with relative protein enrichment.
• Severe hypertriglyceridemia resulted in triglyceride/cholesterol ester ratios exceeding 1.0, potentially leading to underestimation of LDL and HDL levels by cholesterol measurement alone.

Conclusions:

• Elevated triglyceride-rich lipoproteins act as acceptors for cholesterol esters and other components from LDL and HDL.
• Triglyceride transfer to LDL and HDL, likely mediated by lipid transfer proteins, alters lipoprotein structure.
• These structural changes in LDL and HDL contribute to the atherogenic risk associated with hypertriglyceridemia.