Uremia modulates the phenotype of aortic smooth muscle cells.

Background And Aims: Chronic kidney disease leads to uremia and markedly accelerates atherosclerosis. Phenotypic modulation of smooth muscle cells (SMCs) in the arterial media plays a key role in accelerating atherogenesis. The aim of this study was to investigate whether uremia per se modulates the phenotype of aortic SMCs in vivo.

Increased Plasma IgE Accelerate Atherosclerosis in Secreted IgM Deficiency.

Rationale: Deficiency of secreted IgM (sIgM) accelerates atherosclerosis in Ldlrmice. Several atheroprotective effects of increased levels of IgM antibodies have been suggested, including preventing inflammation induced by oxidized low-density lipoprotein and promoting apoptotic cell clearance. However, the mechanisms by which the lack of sIgM promotes lesion formation remain unknown.

Effect of 12-O-tetradecanoylphorbol-13-acetate-induced psoriasis-like skin lesions on systemic inflammation and atherosclerosis in hypercholesterolaemic apolipoprotein E deficient mice.

Background: Risk of cardiovascular disease is increased in patients with psoriasis, but molecular mechanisms linking the two conditions have not been clearly established. Lack of appropriate animal models has hampered generation of new knowledge in this area of research and we therefore sought to develop an animal model with combined atherosclerosis and psoriasis-like skin inflammation.

Methods: Topical 12-O-tetradecanoylphorbol-13-acetate (TPA) was applied to the ears twice per week for 8 weeks in atherosclerosis-prone apolipoprotein E deficient (ApoE(-/-)) mice.

Atheroprotective immunization with malondialdehyde-modified LDL is hapten specific and dependent on advanced MDA adducts: implications for development of an atheroprotective vaccine.

Immunization with homologous malondialdehyde (MDA)-modified LDL (MDA-LDL) leads to atheroprotection in experimental models supporting the concept that a vaccine to oxidation-specific epitopes (OSEs) of oxidized LDL could limit atherogenesis. However, modification of human LDL with OSE to use as an immunogen would be impractical for generalized use. Furthermore, when MDA is used to modify LDL, a wide variety of related MDA adducts are formed, both simple and more complex.

Development and application of a nonradioactive binding assay of oxidized low-density lipoprotein to macrophage scavenger receptors.

Macrophages play a key role in atherogenesis in part through excessive uptake of oxidized LDL (OxLDL) via scavenger receptors. Binding of OxLDL to macrophages has traditionally been assessed using radiolabeled OxLDL. To allow more efficient and convenient measurements, we developed a nonradioactive binding assay in which biotinylated OxLDL (Bt-OxLDL) is added to macrophages in 96-well microtiter culture plates under various conditions and the extent of binding is determined using solid phase chemiluminescent immunoassay techniques.

The pro-atherogenic effects of macrophages are reduced upon formation of a complex between C-reactive protein and lysophosphatidylcholine.

Rationale: C-reactive protein (CRP) and lysophosphatidylcholine (LPC) are phosphorylcholine-(PC)-containing oxidized phospholipids (oxPLs) found in oxidized LDL (oxLDL), which trigger pro-atherogenic activities of macrophages during the process of atherosclerosis. It has been previously reported that CRP binds to the PC head group of oxLDL in a calcium-dependent manner. The aim of this study was to investigate the importance of binding between CRP and LPC to the pro-atherogenic activities of macrophages.

Design and synthesis of a stable oxidized phospholipid mimic with specific binding recognition for macrophage scavenger receptors.

Macrophage scavenger receptors appear to play a major role in the clearance of oxidized phospholipid (OxPL) products. Discrete peptide-phospholipid conjugates with the phosphatidylcholine headgroup have been shown to exhibit binding affinity for these receptors. We report the preparation of a water-soluble, stable peptide-phospholipid conjugate (9) that possesses the necessary physical properties to enable more detailed study of the role(s) of OxPL in metabolic disease.

Peptide mimotopes of malondialdehyde epitopes for clinical applications in cardiovascular disease.

Autoantibodies specific for malondialdehyde-modified LDL (MDA-LDL) represent potential biomarkers to predict cardiovascular risk. However, MDA-LDL is a high variability antigen with limited reproducibility. To identify peptide mimotopes of MDA-LDL, phage display libraries were screened with the MDA-LDL-specific IgM monoclonal Ab LRO4, and the specificity and antigenic properties of MDA mimotopes were assessed in vitro and in vivo.

Human oxidation-specific antibodies reduce foam cell formation and atherosclerosis progression.

Objectives: We sought to assess the in vivo importance of scavenger receptor (SR)-mediated uptake of oxidized low-density lipoprotein (OxLDL) in atherogenesis and to test the efficacy of human antibody IK17-Fab or IK17 single-chain Fv fragment (IK17-scFv), which lacks immunologic properties of intact antibodies other than the ability to inhibit uptake of OxLDL by macrophages, to inhibit atherosclerosis.

Background: The unregulated uptake of OxLDL by macrophage SR contributes to foam cell formation, but the importance of this pathway in vivo is uncertain.

Methods: Cholesterol-fed low-density lipoprotein receptor knockout (LDLR(-/-)) mice were treated with intraperitoneal infusion of human IK17-Fab (2.

Complement factor H binds malondialdehyde epitopes and protects from oxidative stress.

Oxidative stress and enhanced lipid peroxidation are linked to many chronic inflammatory diseases, including age-related macular degeneration (AMD). AMD is the leading cause of blindness in Western societies, but its aetiology remains largely unknown. Malondialdehyde (MDA) is a common lipid peroxidation product that accumulates in many pathophysiological processes, including AMD.

Oxidation-specific epitopes are danger-associated molecular patterns recognized by pattern recognition receptors of innate immunity.

Oxidation reactions are vital parts of metabolism and signal transduction. However, they also produce reactive oxygen species, which damage lipids, proteins and DNA, generating "oxidation-specific" epitopes. In this review, we discuss the hypothesis that such common oxidation-specific epitopes are a major target of innate immunity, recognized by a variety of "pattern recognition receptors" (PRRs).

Oxidized cholesteryl esters and phospholipids in zebrafish larvae fed a high cholesterol diet: macrophage binding and activation.

A novel hypercholesterolemic zebrafish model has been developed to study early events of atherogenesis. This model utilizes optically transparent zebrafish larvae, fed a high cholesterol diet (HCD), to monitor processes of vascular inflammation in live animals. Because lipoprotein oxidation is an important factor in the development of atherosclerosis, in this study, we characterized the oxidized lipid milieu in HCD-fed zebrafish larvae.

Deficiency of antigen-presenting cell invariant chain reduces atherosclerosis in mice.

Background: Adaptive immunity and innate immunity play important roles in atherogenesis. Invariant chain (CD74) mediates antigen-presenting cell antigen presentation and T-cell activation. This study tested the hypothesis that CD74-deficient mice have reduced numbers of active T cells and resist atherogenesis.

Phosphoinositide 3-kinase p110 delta regulates natural antibody production, marginal zone and B-1 B cell function, and autoantibody responses.

B-1 and marginal zone (MZ) B cells produce natural Abs, make Ab responses to microbial pathogens, and contribute to autoimmunity. Although the delta isoform of the PI3K p110 catalytic subunit is essential for development of these innate-like B cells, its role in the localization, activation, and function of normal B-1 and MZ B cells is not known. Using IC87114, a highly selective inhibitor of p110delta enzymatic activity, we show that p110delta is important for murine B-1 and MZ B cells to respond to BCR clustering, the TLR ligands LPS and CpG DNA, and the chemoattractants CXCL13 and sphingosine 1-phosphate.

Oxidation-specific epitopes are dominant targets of innate natural antibodies in mice and humans.

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of oxidized lipoproteins and apoptotic cells. Adaptive immune responses to various oxidation-specific epitopes play an important role in atherogenesis. However, accumulating evidence suggests that these epitopes are also recognized by innate receptors, such as scavenger receptors on macrophages, and plasma proteins, such as C-reactive protein (CRP).

Vascular lipid accumulation, lipoprotein oxidation, and macrophage lipid uptake in hypercholesterolemic zebrafish.

Lipid accumulation in arteries induces vascular inflammation and atherosclerosis, the major cause of heart attack and stroke in humans. Extreme hyperlipidemia induced in mice and rabbits enables modeling many aspects of human atherosclerosis, but microscopic examination of plaques is possible only postmortem. Here we report that feeding adult zebrafish (Danio rerio) a high-cholesterol diet (HCD) resulted in hypercholesterolemia, remarkable lipoprotein oxidation, and fatty streak formation in the arteries.

The role of innate immunity in atherogenesis.

Lipid peroxidation is a common event in health and is greatly accelerated in pro-inflammatory settings such as hypercholesterolemia. Consequently, oxidation-specific epitopes are generated, which are pro-inflammatory and immunogenic, leading to both adaptive and innate responses. Because innate immune mechanisms use conserved germline pattern recognition receptors (PRRs) that are preformed and present at birth, it is not obvious why they should bind to such epitopes.

Oxidation-specific epitopes are important targets of innate immunity.

During the oxidation of LDL, a central pathophysiological component of atherogenesis, a wide variety of chemical and physical changes occur leading to the generation of oxidation-specific neoepitopes. These epitopes are not only immunogenic, leading to adaptive humoral responses, but are also a prominent target of multiple arcs of innate immunity. The pattern recognition receptors (PRRs) of innate immunity are germ line encoded, conserved by natural selection, and bind to pathogen-associated molecular patterns (PAMPs) common on multiple structures.

Natural antibodies in murine atherosclerosis.

Natural antibodies are preformed antibodies that are present even in naive germ-free mice in the absence of any exogenous antigenic exposure. Consistent with their specificities for microbial antigens, natural antibodies play an important non-redundant role in the first line defense against bacterial and viral infections. On the other hand natural antibodies have also been shown to have specificities for self antigens, and therefore have been proposed to provide important homeostatic "house-keeping" functions.

Cholesteryl ester hydroperoxides are biologically active components of minimally oxidized low density lipoprotein.

Oxidation of low density lipoprotein (LDL) occurs in vivo and significantly contributes to the development of atherosclerosis. An important mechanism of LDL oxidation in vivo is its modification with 12/15-lipoxygenase (LO). We have developed a model of minimally oxidized LDL (mmLDL) in which native LDL is modified by cells expressing 12/15LO.

A diet-induced hypercholesterolemic murine model to study atherogenesis without obesity and metabolic syndrome.

Objective: Western-type high-fat/high-cholesterol diets used to induce atherogenesis in low-density lipoprotein (LDL) receptor-deficient mice also lead to obesity with concomitant metabolic complications, eg, hypertriglyceridemia, hyperinsulinemia, and insulin resistance. Our aim was to design a diet inducing atherosclerosis through moderate hypercholesterolemia without associated parameters of the metabolic syndrome.

Methods And Results: Male LDL receptor-deficient mice were fed regular chow (RC; 0.

1 -O-alkyl-2-(omega-oxo)acyl-sn-glycerols from shark oil and human milk fat are potential precursors of PAF mimics and GHB.

This study examines the feasibility that peroxidation and lipolysis of 1-O-alkyl-2,3-diacyl-sn-glycerols (DAGE) found in shark liver oil and human milk fat constitutes a potential source of dietary precursors of platelet activating factor (PAF) mimics and of gamma-hydroxybutyrate (GHB). Purified DAGE were converted into 1-O-alkyl-2-acyl-sn-glycerols by pancreatic lipase, without isomerization, and transformed into 1-O-alkyl-2-oxoacyl-sn-glycerols by mild autooxidation. The various core aldehydes without derivatization, as well as the corresponding dinitrophenylhydrazones, were characterized by chromatographic retention time and diagnostic ions by online electrospray mass spectrometry.

The role of natural antibodies in atherogenesis.

Atherosclerosis is now widely recognized as a chronic inflammatory disease that involves innate and adaptive immune responses. Both cellular and humoral components of the immune system have been implicated in atherogenesis. Natural antibodies can be considered humoral factors of innate immunity, and their functional role in health and disease has been reexamined in recent years.