Interaction Between VLDL and Phosphatidylcholine Liposomes Generates New γ‐LpE‐like Particles

Abstract

One of the subfractions of HDL involved in reverse cholesterol transport is γ-LpE. It has been assumed that, like preβ-LpAI, it can be generated during the interaction between phosphatidylcholine liposomes and lipoproteins and can contribute to more efficient cholesterol efflux after the introduction of liposomes to plasma. However, there has been no evidence concerning what the sources of these particles in plasma might be. Here, we determined whether the interaction of phosphatidylcholine liposomes with VLDL and the subsequent conversions of particles could be a source of new γ-LpE particles. We found that the interaction between liposomes and VLDL affected its lipid and protein composition. The content of phospholipids increased (~96 %) while the content of free cholesterol and apolipoprotein E decreased in VLDL during the reaction with liposomes (~100 and ~24 %, respectively). New particles which did not contain apolipoprotein B were generated. Heterogeneous HDL-sized populations of particles were generated, containing phospholipids and apolipoprotein E as the sole apolipoprotein, with densities from 1.063 to 1.21 g/ml, either with γ-mobility on agarose gel and Stokes diameters from 8.58 to 22.07 nm or with preβ-mobility and Stokes diameters from 9.9 to 21.08 nm. The obtained results contribute to the understanding of changes in lipoproteins under the influence of phosphatidylcholine liposomes, showing the formation of new (γ-LpE)-like and (preβ-LpE)-like particles, similar in mobility and size to plasma HDL-LpE. These newly generated particles can claim a share of the antiatherogenic effects of liposomes, observed in studies both in vitro and in vivo.

Detection of lipoprotein X (LPX) – a challenge in patients with severe hypercholesterolaemia

“…Unlike commercial electrophoresis kits, our laboratory-prepared electrophoresis set clearly demonstrated an additional fraction with g mobility and the green tinge characteristic for particles rich in PL. The applied buffer, which we had previously used in our study with phosphatidylcholine liposomes and gmobility lipoproteins (28), enabled clear differentiation of particles with low electrophoretic mobility. A clear demonstration of the presence of LpX was also presented by Inamoto et al (29), who applied cholesterol and triglyceride staining following lipoprotein electrophoresis.…”

The Differential Effects of HDL Subpopulations on Lipoprotein Lipase (LPL)-Mediated VLDL Catabolism

“…Next, to assess the electrophoretic mobility of the VLDL remnants agarose gel electrophoresis was performed. The VLDL remnant composition was evaluated by separating the remnants from other reaction products by immunoprecipitation with anti-apo B polyclonal antibodies (Dako, Glostrup, Denmark), as described previously [ 18 ], or by ultracentrifugation. Briefly, 0.5 mL of each reaction mixture was adjusted to a density of 1.063 g/ mL by adding solid KBr.…”

Progression of Chronic Kidney Disease Affects HDL Impact on Lipoprotein Lipase (LPL)-Mediated VLDL Lipolysis Efficiency

“…3, corresponding to the volume of HDL and/or LPL, was added to align the differences in volumes between the reaction mixtures. After incubation, the VLDL was separated by immunoprecipitation with anti-apoB antibodies [16], and the concentration and the percentage of TG released from the VLDL during lipolysis was calculated.…”