Small, Dense High-Density Lipoprotein-3 Particles Are Enriched in Negatively Charged Phospholipids

Abstract

Objective— High-density lipoprotein (HDL) displays multiple atheroprotective activities and is highly heterogeneous in structure, composition, and function; the molecular determinants of atheroprotective functions of HDL are incompletely understood. Because phospholipids represent a major bioactive lipid component of HDL, we characterized the phosphosphingolipidome of major normolipidemic HDL subpopulations and related it to HDL functionality. Approach and Results— Using an original liquid chromatography–mass spectrometry/mass spectrometry methodology for phospholipid and sphingolipid profiling, 162 individual molecular lipid species were quantified across the 9 lipid subclasses, in the order of decreasing abundance, phosphatidylcholine>sphingomyelin>lysophosphatidylcholine>phosphatidylethanolamine>phosphatidylinositol>ceramide>phosphatidylserine>phosphatidylglycerol>phosphatidic acid. When data were expressed relative to total lipid, the contents of lysophosphatidylcholine and of negatively charged phosphatidylserine and phosphatidic acid increased progressively with increase in hydrated density of HDL, whereas the proportions of sphingomyelin and ceramide decreased. Key biological activities of HDL subpopulations, notably cholesterol efflux capacity from human THP-1 macrophages, antioxidative activity toward low-density lipoprotein oxidation, antithrombotic activity in human platelets, cell-free anti-inflammatory activity, and antiapoptotic activity in endothelial cells, were predominantly associated with small, dense, protein-rich HDL3. The biological activities of HDL particles were strongly intercorrelated, exhibiting significant correlations with multiple components of the HDL phosphosphingolipidome. Specifically, the content of phosphatidylserine revealed positive correlations with all metrics of HDL functionality, reflecting enrichment of phosphatidylserine in small, dense HDL3. Conclusions— Our structure–function analysis thereby reveals that the HDL lipidome may strongly affect atheroprotective functionality.

Structure of HDL: Particle Subclasses and Molecular Components

“…The pioneering study of Wiesner and colleagues published in 2009 (Wiesner et al 2009) provided reference values for the lipidome of HDL isolated from healthy normolipidemic controls by FPLC. In an attempt to further characterise HDL composition and address its inherent heterogeneity, we recently reported the phospho-and sphingolipidome of five major HDL subpopulations isolated from healthy normolipidemic subjects (Camont et al 2013). …”

Dysfunctional high-density lipoproteins in coronary heart disease: implications for diagnostics and therapy

“…91 In fact, most of the phosholipid molecular species identified by liquid-chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) profiling of HDL particles could be linked to an atheroprotective biological activity of HDL. 86 Especially, a strong relationship existed between the content of negatively charged phosphatidylserine and various metrics of HDL function, i.e. the cholesterol efflux capacity from THP-1 cells, the anti-oxidative activity towards LDL, the ability to counteract platelet activation, the anti-inflammatory properties in a cell-free assay, and the potential to protect endothelial cells from apoptosis.…”

“…the cholesterol efflux capacity from THP-1 cells, the anti-oxidative activity towards LDL, the ability to counteract platelet activation, the anti-inflammatory properties in a cell-free assay, and the potential to protect endothelial cells from apoptosis. 86 Artificial enrichment of HDL3 with phosphatidylcholines increased SR-BI-mediated cholesterol efflux. 92 The same investigators subsequently showed that enhanced in vivo hydrolysis of HDL phospholipids by overexpression of endothelial lipase in human apoA-I transgenic mice caused pronounced reductions in the serum phospholipid/apoA-I ratio and attenuated the capacity of serum to mediate cholesterol efflux via SR-BI by 90%, whereas the ABCA1-dependent efflux potential increased by 63%.…”

“…20 Endothelial HDL dysfunction has been assigned to the loss of S1P, 119 oxidative modifications of apoA-I or phospholipids, 40 enrichment with SAA 65 or SDMA. 41 Likewise, differences in cholesterol efflux capacity have been attributed to differences in HDL particle number, HDL subclass distribution, phospholipid composition, 86 the presence of SAA, 58-61 or posttranslational modifications. [127][128][129][130][131][132] As yet it is not clear whether these findings reflect redundancy or complexity of HDL interactions with endothelial cells or result from confounding.…”

Adipocyte ATP-Binding Cassette G1 Promotes Triglyceride Storage, Fat Mass Growth, and Human Obesity

“…Lower organic phases were dried in nitrogen, resuspended, and transferred into liquid chromatography-mass spectrometry (LC-MS) amber vials with inserts. LC-MS analysis and SM quantification were performed as previously described (17). The percentage of SM efflux was calculated as 100 3 (medium SM)/(medium SM + cell SM).…”