Using adenovirus-mediated gene transfer to study the effect of myeloperoxidase on plasma lipid levels, HDL structure and functionality in mice expressing human apoA-I forms.

Apolipoprotein A-I (apoA-I), the main protein component of High-Density Lipoprotein (HDL), is modified in plasma and the arterial wall by various enzymes. Myeloperoxidase (MPO), a leukocyte-derived peroxidase, is highly expressed during inflammation and associates with HDL reducing its functionality and contributing to atherosclerosis. In the present study we sought to explore further the effect of MPO on HDL structure and functionality in vivo using adenovirus-mediated gene transfer of human MPO combined with human apoA-I forms containing substitutions at MPO-sensitive sites or wild type apoA-I.

Reconstituted HDL-apoE3 promotes endothelial cell migration through ID1 and its downstream kinases ERK1/2, AKT and p38 MAPK.

Introduction: Atherosclerotic Coronary Artery Disease (ASCAD) is the leading cause of mortality worldwide. Novel therapeutic approaches aiming to improve the atheroprotective functions of High Density Lipoprotein (HDL) include the use of reconstituted HDL forms containing human apolipoprotein A-I (rHDL-apoA-I). Given the strong atheroprotective properties of apolipoprotein E3 (apoE3), rHDL-apoE3 may represent an attractive yet largely unexplored therapeutic agent.

Direct-to-Implant Breast Reconstruction with Simultaneous Nipple-Sparing Mastopexy Utilizing an Inferiorly Based Adipodermal Flap: Our Experience with Prepectoral and Subpectoral Techniques.

Background: Direct-to-implant breast reconstruction continues to grow in popularity among reconstructive breast surgeons and patients alike. Women with large breasts and ptosis are often thought not to be candidates for nipple sparing or direct-to-implant reconstruction. The authors utilized a single-stage, nipple-sparing, direct-to-implant reconstruction with simultaneous mastopexy, while the nipple-areolar complex was kept viable on an inferiorly based adipodermal flap in a single stage.

HDL-apoA-I induces the expression of angiopoietin like 4 (ANGPTL4) in endothelial cells via a PI3K/AKT/FOXO1 signaling pathway.

Background: High Density Lipoprotein (HDL) and its main protein component, apolipoprotein A-I (apoA-I), have numerous atheroprotective functions on various tissues including the endothelium. Therapies based on reconstituted HDL containing apoA-I (rHDL-apoA-I) have been used successfully in patients with acute coronary syndrome, peripheral vascular disease or diabetes but very little is known about the genomic effects of rHDL-apoA-I and how they could contribute to atheroprotection.

Objective: The present study aimed to understand the endothelial signaling pathways and the genes that may contribute to rHDL-apoA-I-mediated atheroprotection.

ApoE isoforms and carboxyl-terminal-truncated apoE4 forms affect neuronal BACE1 levels and Aβ production independently of their cholesterol efflux capacity.

The β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) initiates the production of amyloid-β peptide (Aβ), which is central to the pathogenesis of Alzheimer's disease (AD). Changes in brain cholesterol homeostasis have been suggested to affect Aβ metabolism. Cholesterol homeostasis is maintained in the brain by apolipoprotein E (apoE).

Outcomes by molecular subtype after accelerated partial breast irradiation using single-entry catheters.

Purpose: Tumor biology is being recognized as an important indicator of prognosis and risk of locoregional recurrence. Here, we determine actuarial recurrence rates by approximated molecular subtype for women treated with single-entry catheter accelerated partial breast irradiation (sAPBI).

Methods And Materials: One thousand four hundred eighty-six women with invasive cancer having known ER, PR, and Her2 status and at least 1-year of followup were treated using MammoSite, Contura, or SAVI sAPBI from 2002 to 2014 at our institution.

Role of apolipoproteins, ABCA1 and LCAT in the biogenesis of normal and aberrant high density lipoproteins.

In this review, we focus on the pathway of biogenesis of HDL, the essential role of apoA-I, ATP binding cassette transporter A1 (ABCA1), and lecithin: cholesterol acyltransferase (LCAT) in the formation of plasma HDL; the generation of aberrant forms of HDL containing mutant apoA-I forms and the role of apoA-IV and apoE in the formation of distinct HDL subpopulations. The biogenesis of HDL requires functional interactions of the ABCA1 with apoA-I (and to a lesser extent with apoE and apoA-IV) and subsequent interactions of the nascent HDL species thus formed with LCAT. Mutations in apoA-I, ABCA1 and LCAT either prevent or impair the formation of HDL and may also affect the functionality of the HDL species formed.

Tissue Uptake Mechanisms Involved in the Clearance of Non-Protein Nanoparticles that Mimic LDL Composition: A Study with Knockout and Transgenic Mice.

Lipid core nanoparticles (LDE) resembling LDL behave similarly to native LDL when injected in animals or subjects. In contact with plasma, LDE acquires apolipoproteins (apo) E, A-I and C and bind to LDL receptors. LDE can be used to explore LDL metabolism or as a vehicle of drugs directed against tumoral or atherosclerotic sites.

LXR Agonism Upregulates the Macrophage ABCA1/Syntrophin Protein Complex That Can Bind ApoA-I and Stabilized ABCA1 Protein, but Complex Loss Does Not Inhibit Lipid Efflux.

Macrophage ABCA1 effluxes lipid and has anti-inflammatory activity. The syntrophins, which are cytoplasmic PDZ protein scaffolding factors, can bind ABCA1 and modulate its activity. However, many of the data assessing the function of the ABCA1-syntrophin interaction are based on overexpression in nonmacrophage cells.

Natural human apoA-I mutations L141RPisa and L159RFIN alter HDL structure and functionality and promote atherosclerosis development in mice.

Objective: Mutations in human apolipoprotein A-I (apoA-I) are associated with low high-density lipoprotein (HDL) cholesterol levels and pathological conditions such as premature atherosclerosis and amyloidosis. In this study we functionally characterized two natural human apoA-I mutations, L141RPisa and L159RFIN, in vivo.

Methods: We generated transgenic mice expressing either wild-type (WT) or the two mutant forms of human apoA-I on a mouse apoA-I(-/-) background and analyzed for abnormalities in their lipid and lipoprotein profiles.

Influence of Isoforms and Carboxyl-Terminal Truncations on the Capacity of Apolipoprotein E To Associate with and Activate Phospholipid Transfer Protein.

Phospholipid transfer protein (PLTP), a main protein in lipid and lipoprotein metabolism, exists in high-activity (HA-PLTP) and low-activity (LA-PLTP) forms in human plasma. Proper phospholipid transfer activity of PLTP is modulated by interactions with various apolipoproteins (apo) including apoE. The domains of apoE involved in interactions with PLTP are not known.

The Effect of Natural LCAT Mutations on the Biogenesis of HDL.

We have investigated how the natural LCAT[T147I] and LCAT[P274S] mutations affect the pathway of biogenesis of HDL. Gene transfer of WT LCAT in LCAT(-/-) mice increased 11.8-fold the plasma cholesterol, whereas the LCAT[T147I] and LCAT[P274S] mutants caused a 5.

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.

Regulation of HDL genes: transcriptional, posttranscriptional, and posttranslational.

HDL regulation is exerted at multiple levels including regulation at the level of transcription initiation by transcription factors and signal transduction cascades; regulation at the posttranscriptional level by microRNAs and other noncoding RNAs which bind to the coding or noncoding regions of HDL genes regulating mRNA stability and translation; as well as regulation at the posttranslational level by protein modifications, intracellular trafficking, and degradation. The above mechanisms have drastic effects on several HDL-mediated processes including HDL biogenesis, remodeling, cholesterol efflux and uptake, as well as atheroprotective functions on the cells of the arterial wall. The emphasis is on mechanisms that operate in physiologically relevant tissues such as the liver (which accounts for 80% of the total HDL-C levels in the plasma), the macrophages, the adrenals, and the endothelium.

HDL biogenesis, remodeling, and catabolism.

In this chapter, we review how HDL is generated, remodeled, and catabolized in plasma. We describe key features of the proteins that participate in these processes, emphasizing how mutations in apolipoprotein A-I (apoA-I) and the other proteins affect HDL metabolism. The biogenesis of HDL initially requires functional interaction of apoA-I with the ATP-binding cassette transporter A1 (ABCA1) and subsequently interactions of the lipidated apoA-I forms with lecithin/cholesterol acyltransferase (LCAT).

apoE3[K146N/R147W] acts as a dominant negative apoE form that prevents remnant clearance and inhibits the biogenesis of HDL.

The K146N/R147W substitutions in apoE3 were described in patients with a dominant form of type III hyperlipoproteinemia. The effects of these mutations on the in vivo functions of apoE were studied by adenovirus-mediated gene transfer in different mouse models. Expression of the apoE3[K146N/R147W] mutant in apoE-deficient (apoE(-/-)) or apoA-I-deficient (apoA-I(-/-))×apoE(-/-) mice exacerbated the hypercholesterolemia and increased plasma apoE and triglyceride levels.

Significance of the hydrophobic residues 225-230 of apoA-I for the biogenesis of HDL.

We studied the significance of four hydrophobic residues within the 225-230 region of apoA-I on its structure and functions and their contribution to the biogenesis of HDL. Adenovirus-mediated gene transfer of an apoA-I[F225A/V227A/F229A/L230A] mutant in apoA-I⁻/⁻ mice decreased plasma cholesterol, HDL cholesterol, and apoA-I levels. When expressed in apoA-I⁻/⁻ × apoE⁻/⁻ mice, approximately 40% of the mutant apoA-I as well as mouse apoA-IV and apoB-48 appeared in the VLDL/IDL/LDL.

Role of the hydrophobic and charged residues in the 218-226 region of apoA-I in the biogenesis of HDL.

We investigated the significance of hydrophobic and charged residues 218-226 on the structure and functions of apoA-I and their contribution to the biogenesis of HDL. Adenovirus-mediated gene transfer of apoA-I[L218A/L219A/V221A/L222A] in apoA-I⁻/⁻ mice decreased plasma cholesterol and apoA-I levels to 15% of wild-type (WT) control mice and generated pre-β- and α4-HDL particles. In apoA-I⁻/⁻ × apoE⁻/⁻ mice, the same mutant formed few discoidal and pre-β-HDL particles that could not be converted to mature α-HDL particles by excess LCAT.

Effect of apoA-I Mutations in the Capacity of Reconstituted HDL to Promote ABCG1-Mediated Cholesterol Efflux.

ATP binding cassette transporter G1 (ABCG1) mediates the cholesterol transport from cells to high-density lipoprotein (HDL), but the role of apolipoprotein A-I (apoA-I), the main protein constituent of HDL, in this process is not clear. To address this, we measured cholesterol efflux from HEK293 cells or J774 mouse macrophages overexpressing ABCG1 using as acceptors reconstituted HDL (rHDL) containing wild-type or various mutant apoA-I forms. It was found that ABCG1-mediated cholesterol efflux was severely reduced (by 89%) when using rHDL containing the carboxyl-terminal deletion mutant apoA-I[Δ(185-243)].

Allele-dependent thermodynamic and structural perturbations in ApoE variants associated with the correction of dyslipidemia and formation of spherical ApoE-containing HDL particles.

Overexpression of ApoE4[Leu261Ala/Trp264Ala/Phe265Ala] mutant (ApoE4mutC) prevents hypertriglyceridemia and promotes formation of spherical ApoE-containing HDL in ApoE(-/-) or ApoA-I(-/-) mice. Although, a similar phenotype was observed with ApoE2[Leu261Ala/Trp264Ala/Phe265Ala] (ApoE2mutC), small differences in cholesterol distribution to IDL/LDL, HDL2 and HDL3 fractions and ApoE distribution to HDL2 and HDL3 fractions suggested that ApoE allelic background can influence mutant ApoE properties. To understand the structural basis behind the properties of ApoE2mutC and ApoE4mutC variants we analyzed their structural and thermodynamic integrity in comparison to their wild-type counterparts.

ApoA-IV promotes the biogenesis of apoA-IV-containing HDL particles with the participation of ABCA1 and LCAT.

The objective of this study was to establish the role of apoA-IV, ABCA1, and LCAT in the biogenesis of apoA-IV-containing HDL (HDL-A-IV) using different mouse models. Adenovirus-mediated gene transfer of apoA-IV in apoA-I(-/-) mice did not change plasma lipid levels. ApoA-IV floated in the HDL2/HDL3 region, promoted the formation of spherical HDL particles as determined by electron microscopy, and generated mostly α- and a few pre-β-like HDL subpopulations.

Pharmacodynamic and pharmacokinetic analysis of apoE4 [L261A, W264A, F265A, L268A, V269A], a recombinant apolipoprotein E variant with improved biological properties.

Physiological levels of wild-type (wt) apolipoprotein E (apoE) in plasma mediate the clearance of cholesterol-rich atherogenic lipoprotein remnants while higher than normal plasma apoE concentrations fail to do so and trigger hypertriglyceridemia. This property of wt apoE reduces significantly its therapeutic value as a lead biological for the treatment of dyslipidemia. Recently, we reported the generation of a recombinant apoE variant, apoE4 [L261A, W264A, F265A, L268A, V269A] (apoE4mut1) with improved biological functions.

Tumor bed control with balloon-based accelerated partial breast irradiation: incidence of true recurrences versus elsewhere failures in the American Society of Breast Surgery MammoSite(®) Registry Trial.

Background: Randomized trials demonstrate that lumpectomy plus whole-breast irradiation (WBI) yields survival equivalent to mastectomy. Studies that use WBI, however, typically report higher tumor bed recurrence rates than elsewhere failures (EF) (historically considered new primary lesions). The rate of true recurrence (TR) versus EF was queried for a large patient cohort treated with accelerated partial breast irradiation (APBI).