Effect of Lipid Composition on the Atheroprotective Properties of HDL-Mimicking Micelles

Antiplatelet Effects of DMPC-Based Synthetic High-Density Lipoproteins: Exploring Particle Structure and Noncholesterol Efflux Mechanisms

Platelet activation is a key factor in the development of cardiovascular diseases. High-density lipoprotein (HDL) is known for its cardioprotective activities including antithrombotic actions. While HDL mimetics have been explored for their potential to regulate thrombosis, their influence on platelet activity remains unclear. This study explores the capacity of synthetic HDL (sHDL) to modulate platelet function and investigates the underlying mechanisms. We examined the effects of sHDL, formulated with various ApoA1 mimetic peptides (18A, 5A, and 22A) and full-length ApoA1 protein, all complexed with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), on platelet function. DMPC-based sHDL demonstrated pronounced antiplatelet effects across all formulations. Comparison with DMPC micelles showed that all sHDL molecules were more effective, highlighting the crucial role of the protein-phospholipid complex in reducing platelet reactivity. Further analysis revealed that DMPC sHDL dose-dependently inhibited various platelet functions, including aggregation, integrin activation, α-granule secretion, protein kinase C (PKC) activation, and platelet spreading. Mechanistic studies demonstrated that DMPC sHDL's antiplatelet effects are not entirely dependent on cholesterol efflux, despite effectively reducing total platelet cholesterol. Furthermore, sHDL's activity was found to be independent of scavenger receptor BI (SR-BI). Notably, inhibition of the CD36 receptor markedly attenuated sHDL's antiplatelet activity and uptake, suggesting a novel mechanism distinct from that of native HDL. In summary, DMPC sHDL modulates platelet function through a synergistic action between protein and phospholipid components, primarily via CD36 receptor engagement. These insights pave the way for novel antiplatelet therapies utilizing sHDL's distinct properties.

Comparison of cholesterol transport capacity of peptide- and polymer-based lipid Nanodiscs

Apolipoprotein-based, synthetic high-density lipoprotein (sHDL) nanodiscs have been extensively studied as a potential therapeutic agent for cardiovascular disease due to their ability to promote reverse cholesterol transport. Recently, polymer-based nanodiscs have been made possible with the development of novel polymeric materials such as styrene-maleic anhydride copolymer (SMA). While the polymer-based nanodiscs resemble the discoidal structure of sHDLs, their functional similarity with sHDL has not been investigated. In the present study, we compared the SMA-based and peptide-based sHDL nanodiscs focusing on their cholesterol mobilization effects. Results showed that SMA-based nanoparticles presented similar particle size and in vitro cholesterol efflux effect to those of sHDL nanodiscs. However, SMA nanodiscs induced less cholesterol mobilization in vivo, possibly due to insufficient cholesterol esterification by lecithin:cholesterol acyltransferase.

Non-alcoholic fatty liver disease is characterised by a reduced polyunsaturated fatty acid transport via free fatty acids and high-density lipoproteins (HDL)

BACKGROUND AND OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) develops due to impaired hepatic lipid fluxes and is a risk factor for chronic liver disease and atherosclerosis. Lipidomic studies consistently reported characteristic hepatic/VLDL "lipid signatures" in NAFLD; whole plasma traits are more debated. Surprisingly, the HDL lipid composition by mass spectrometry has not been characterised across the NAFLD spectrum, despite HDL being a possible source of hepatic lipids delivered from peripheral tissues alongside free fatty acids (FFA). This study characterises the HDL lipidomic signature in NAFLD, and its correlation with metabolic and liver disease markers.

METHODS

We used liquid chromatography-mass spectrometry to determine the whole serum and HDL lipidomic profile in 89 biopsy-proven NAFLD patients and 20 sex and age-matched controls.

RESULTS

In the whole serum of NAFLD versus controls, we report a depletion in polyunsaturated (PUFA) phospholipids (PL) and FFA; with PUFA PL being also lower in HDL, and negatively correlated with BMI, insulin resistance, triglycerides, and hepatocyte ballooning. In the HDL of the NAFLD group we also describe higher saturated ceramides, which positively correlate with insulin resistance and transaminases.

CONCLUSION

NAFLD features lower serum lipid species containing polyunsaturated fatty acids; the most affected lipid fractions are FFA and (HDL) phospholipids; our data suggest a possible defect in the transfer of PUFA from peripheral tissues to the liver in NAFLD. Mechanistic studies are required to explore the biological implications of our findings addressing if HDL composition can influence liver metabolism and damage, thus contributing to NAFLD pathophysiology.