Native-native 2D gel electrophoresis for HDL subpopulation analysis

Different behavior of Ferguson plot between agarose and polyacrylamide gels

In this study, we conducted Ferguson plot analyses using both agarose and polyacrylamide gels in native electrophoresis and SDS-PAGE. The results revealed intriguing differences in the behavior of bovine serum albumin (BSA) and other model proteins. Specifically, BSA exhibited Ferguson plot slopes that were dependent on the oligomer size in agarose native gel electrophoresis, while such size-dependent behavior was not observed in native-PAGE or SDS-PAGE. These findings suggest that Ferguson plot analysis is a suitable approach when using agarose gel under the electrophoretic conditions employed in this study. Furthermore, our investigation extended to model proteins with acidic isoelectric points and larger molecular weights, namely Ferritin and caseinolytic peptidase B (ClpB). Notably, these proteins displayed distinct Ferguson plot slopes when subjected to agarose gel electrophoresis. Intriguingly, when polyacrylamide gel was employed, ClpB exhibited multiple bands, each with its unique Ferguson plot slope, deviating from the expected behavior based on molecular size. This divergence in Ferguson plot characteristics between agarose and polyacrylamide gels points to an interesting and complex interplay between protein properties and gel electrophoresis conditions.

Development of a novel two-dimensional gel electrophoresis protocol with agarose native gel electrophoresis

A new protocol for conducting two-dimensional (2D) electrophoresis was developed by combining the recently developed agarose native gel electrophoresis with either vertical sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) or flat SDS agarose gel electrophoresis. Our innovative technique utilizes His/MES buffer (pH 6.1) during the first-dimensional (1D) agarose native gel electrophoresis, which allows for the simultaneous and clear visualization of basic and acidic proteins in their native states or complex structures. Our agarose gel electrophoresis is a true native electrophoresis, unlike blue native-PAGE, which relies on the intrinsic charged states of the proteins and their complexes without the need for dye binding. In the 2D, the gel strip from the 1D agarose gel electrophoresis is soaked in SDS and placed on top of the vertical SDS-PAGE gels or the edge of the flat SDS-MetaPhor high-resolution agarose gels. This allows for customized operation using a single electrophoresis device at a low cost. This technique has been successfully applied to analyze various proteins, including five model proteins (BSA, factor Xa, ovotransferrin, IgG, and lysozyme), monoclonal antibodies with slightly different isoelectric points, polyclonal antibodies, and antigen-antibody complexes, as well as complex proteins such as IgM pentamer and β-galactosidase tetramer. Our protocol can be completed within a day, taking approximately 5-6 h, and can be expanded further into Western blot analysis, mass spectrometry analysis, and other analytical methods.

A New Method to Characterize Conformation-Specific Antibody by a Combination of Agarose Native Gel Electrophoresis and Contact Blotting

In this study, we review the agarose native gel electrophoresis that separates proteins and macromolecular complexes in their native state and transfer of the separated proteins from the agarose gel to membranes by contact blotting which retains the native state of these structures. Green fluorescent protein showed functional state both on agarose gel and blotted membrane. Based on the combined procedures, we discovered conformation-specific monoclonal antibodies against PLXDC2 and SARS-CoV-2 spike protein.

(r)HDL in theranostics: how do we apply HDL's biology for precision medicine in atherosclerosis management?

High-density lipoproteins (HDL) are key players in cholesterol metabolism homeostasis since they are responsible for transporting excess cholesterol from peripheral tissues to the liver. Imbalance in this process, due to either excessive accumulation or impaired clearance, results in net cholesterol accumulation and increases the risk of cardiovascular disease (CVD). Therefore, significant effort has been focused on the development of therapeutic tools capable of either directly or indirectly enhancing HDL-guided reverse cholesterol transport (RCT). More recently, in light of the emergence of precision nanomedicine, there has been renewed research interest in attempting to take advantage of the development of advanced recombinant HDL (rHDL) for both therapeutic and diagnostic purposes. In this review, we provide an update on the different approaches that have been developed using rHDL, focusing on the rHDL production methodology and rHDL applications in theranostics. We also compile a series of examples highlighting potential future perspectives in the field.

Influence of route of administration and lipidation of apolipoprotein A-I peptide on pharmacokinetics and cholesterol mobilization

apoA-I, apoA-I mimetic peptides, and their lipid complexes or reconstituted high-density lipoprotein (HDL) have been studied as treatments for various pathologies. However, consensus is lacking about the best method for administration, by intravenous (IV) or intraperitoneal (IP) routes, and formulation, as an HDL particle or in a lipid-free form. The objective of this study was to systematically examine peptide plasma levels, cholesterol mobilization, and lipoprotein remodeling in vivo following administration of lipid-free apoA-I peptide (22A) or phospholipid reconstituted 22A-sHDL by IV and IP routes. The mean circulation half-life was longer for 22A-sHDL (T1/2 = 6.27 h) than for free 22A (T1/2 = 3.81 h). The percentage of 22A absorbed by the vascular compartment after the IP dosing was ∼50% for both 22A and 22A-sHDL. The strongest pharmacologic response came from IV injection of 22A-sHDL, specifically a 5.3-fold transient increase in plasma-free cholesterol (FC) level compared with 1.3- and 1.8-fold FC increases for 22A-IV and 22A-sHDL-IP groups. Addition of either 22A or 22A-sHDL to rat plasma caused lipoprotein remodeling and appearance of a lipid-poor apoA-I. Hence, both the route of administration and the formulation of apoA-I peptide significantly affect its pharmacokinetics and pharmacodynamics.

The effect of phospholipid composition of reconstituted HDL on its cholesterol efflux and anti-inflammatory properties

The goal of this study was to understand how the reconstituted HDL (rHDL) phospholipid (PL) composition affects its cholesterol efflux and anti-inflammatory properties. An ApoA-I mimetic peptide, 5A, was combined with either SM or POPC. Both lipid formulations exhibited similar in vitro cholesterol efflux by ABCA1, but 5A-SM exhibited higher ABCG1- and SR-BI-mediated efflux relative to 5A-POPC (P < 0.05). Injection of both rHDLs in rats resulted in mobilization of plasma cholesterol, although the relative potency was 3-fold higher for the same doses of 5A-SM than for 5A-POPC. Formation of preβ HDL was observed following incubation of rHDLs with both human and rat plasma in vitro, with 5A-SM inducing a higher extent of preβ formation relative to 5A-POPC. Both rHDLs exhibited anti-inflammatory properties, but 5A-SM showed higher inhibition of TNF-α, IL-6, and IL-1β release than did 5A-POPC (P < 0.05). Both 5A-SM and 5A-POPC showed reduction in total plaque area in ApoE(-/-) mice, but only 5A-SM showed a statistically significant reduction over placebo control and baseline (P < 0.01). The type of PL used to reconstitute peptide has significant influence on rHDL's anti-inflammatory and anti-atherosclerosis properties.

High-density lipoprotein attenuates Th1 and th17 autoimmune responses by modulating dendritic cell maturation and function

Aberrant levels and function of the potent anti-inflammatory high-density lipoprotein (HDL) and accelerated atherosclerosis have been reported in patients with autoimmune inflammatory diseases. Whether HDL affects the development of an autoimmune response remains elusive. In this study, we used apolipoprotein A-I-deficient (apoA-I(-/-)) mice, characterized by diminished circulating HDL levels, to delineate the role of HDL in autoimmunity. ApoA-I(-/-) mice exhibited increased severity of Ag-induced arthritis compared with wild-type mice, and this was associated with elevated Th1 and Th17 cell reactivity in the draining lymph nodes. Furthermore, reconstituted HDL (rHDL) attenuated IFN-γ and IL-17 secretion by Ag-specific T cells upon stimulation of draining lymph nodes in vitro. The suppressive effects of rHDL were mediated through modulation of dendritic cell (DC) function. Specifically, rHDL-treated DCs demonstrated an immature phenotype characterized by downregulated costimulatory molecules, the release of low amounts of proinflammatory cytokines, and failure to promote T cell proliferation in vitro. The mechanism of action involved the inhibition of NF-κB nuclear translocation and the decrease of Myd88 mRNA levels by rHDL. Finally, modulation of DC function by rHDL was critically dependent on the presence of scavenger receptor class B type I and ATP Binding Cassette Transporter A1, but not the ATP Binding Cassette Transporter G1. These findings reveal a novel role of HDL in the regulation of adaptive inflammatory responses through suppression of DC function that could be exploited therapeutically in autoimmune inflammatory diseases.

High density lipoproteins: Measurement techniques and potential biomarkers of cardiovascular risk

Plasma high density lipoprotein cholesterol (HDL) comprises a heterogeneous family of lipoprotein species, differing in surface charge, size and lipid and protein compositions. While HDL cholesterol (C) mass is a strong, graded and coherent biomarker of cardiovascular risk, genetic and clinical trial data suggest that the simple measurement of HDL-C may not be causal in preventing atherosclerosis nor reflect HDL functionality. Indeed, the measurement of HDL-C may be a biomarker of cardiovascular health. To assess the issue of HDL function as a potential therapeutic target, robust and simple analytical methods are required. The complex pleiotropic effects of HDL make the development of a single measurement challenging. Development of laboratory assays that accurately HDL function must be developed validated and brought to high-throughput for clinical purposes. This review discusses the limitations of current laboratory technologies for methods that separate and quantify HDL and potential application to predict CVD, with an emphasis on emergent approaches as potential biomarkers in clinical practice.

HDL-cholesterol in coronary artery disease risk: function or structure?

High-density lipoproteins (HDL) are inversely related with coronary artery disease (CAD) and HDL-cholesterol is the only standardized and reproducible parameter available to estimate plasma concentration of these lipoproteins. However, pharmacological interventions intended to increase HDL-cholesterol have not been consistently associated to an effective CAD risk reduction. Among patients with a myocardial infarction, 43 and 44% of men and women, respectively, had normal plasma levels of HDL-cholesterol, whereas genetic studies have failed to show a causal association between HDL-cholesterol and CAD risk. Instead, HDL functionality seems to be the target to be evaluated, but the existing methods are still poorly reproducible and far to be adapted to the clinical laboratory. HDL subclasses rise as a potential alternative for the evaluation of CAD risk; HDL subclasses are a surrogate of intravascular metabolism of these lipoproteins and probably of their functionality. Low levels of large HDL and increased proportions of small particles are the most remarkable features associated to an increased risk of type 2 diabetes mellitus (T2DM) or CAD. However, inflammation and other environmental factors are related with abnormal HDL structure, and, as a consequence, more prospective studies are needed to better support the clinical usefulness of HDL subclasses. New insights from proteome and lipidome profiles of HDL will provide potential HDL-related biomarkers in the coming years.