Colony stimulating factor 1 receptor (Csf1r) expressing cell ablation in mafia (macrophage-specific Fas-induced apoptosis) mice alters monocyte landscape and atherosclerotic lesion characteristics.

Macrophage infiltration and accumulation in the atherosclerotic lesion are associated with plaque progression and instability. Depletion of macrophages from the lesion might provide valuable insights into plaque stabilization processes. Therefore, we assessed the effects of systemic and local macrophage depletion on atherogenesis.

CCL18 aggravates atherosclerosis by inducing CCR6-dependent T-cell influx and polarization.

Introduction: The CC chemokine ligand 18 (CCL18) is a chemokine highly expressed in chronic inflammation in humans. Recent observations of elevated CCL18 plasma levels in patients with acute cardiovascular syndromes prompted an investigation into the role of CCL18 in the pathogenesis of human and mouse atherosclerosis.

Methods And Results: CCL18 was profoundly upregulated in ruptured human atherosclerotic plaque, particularly within macrophages.

Perspective: Hepatocyte-Directed Base Editing as Novel Treatment for Human Dyslipidemia-Current Status and Remaining Challenges.

Hyperlipidemia is a major risk factor for the development of atherosclerotic cardiovascular disease. Lipid-lowering drug therapies therefore still form the heart of the ongoing battle against the occurrence of cardiovascular events. However, in light of the important improvements in gene interference and editing that have been made during the last 2 decades, gene therapy-the genetic modification of cells to produce a permanent therapeutic effect-is currently employed to relief hypercholesterolemic subjects from their potential (chronic) cardiovascular disease burden.

Magnetic resonance imaging contrast-enhancement with superparamagnetic iron oxide nanoparticles amplifies macrophage foam cell apoptosis in human and murine atherosclerosis.

Aims: (Ultra) Small superparamagnetic iron oxide nanoparticles, (U)SPIO, are widely used as magnetic resonance imaging contrast media and assumed to be safe for clinical applications in cardiovascular disease. As safety tests largely relied on normolipidaemic models, not fully representative of the clinical setting, we investigated the impact of (U)SPIOs on disease-relevant endpoints in hyperlipidaemic models of atherosclerosis.

Methods And Results: RAW264.

N-Acetyl Galactosamine Targeting: Paving the Way for Clinical Application of Nucleotide Medicines in Cardiovascular Diseases.

While the promise of oligonucleotide therapeutics, such as (chemically modified) ASO (antisense oligonucleotides) and short interfering RNAs, is undisputed from their introduction onwards, their unfavorable pharmacokinetics and intrinsic capacity to mobilize innate immune responses, were limiting widespread clinical use. However, these major setbacks have been tackled by breakthroughs in chemistry, stability and delivery. When aiming an intervention hepatic targets, such as lipid and sugar metabolism, coagulation, not to mention cancer and virus infection, introduction of N-acetylgalactosamine aided targeting technology has advanced the field profoundly and by now a dozen of N-acetylgalactosamine therapeutics for these indications have been approved for clinical use or have progressed to clinical trial stage 2 to 3 testing.

Impact of bone marrow ATP-binding cassette transporter A1 deficiency on atherogenesis is independent of the presence of the low-density lipoprotein receptor.

Background And Aims: There is extensive evidence from bone marrow transplantation studies that hematopoietic ATP binding cassette A1 (Abca1) is atheroprotective in low-density lipoprotein receptor (Ldlr) deficient mice. In contrast, studies using lysosyme M promoter-driven deletion of Abca1 in Ldlr deficient mice failed to show similar effects. It was hypothesized that the discrepancy between these studies might be due to the presence of Ldlr in bone marrow-derived cells in the transplantation model.

Disruption of Phospholipid Transfer Protein-Mediated High-Density Lipoprotein Maturation Reduces Scavenger Receptor BI Deficiency-Driven Atherosclerosis Susceptibility Despite Unexpected Metabolic Complications.

Objective: We tested the hypothesis that enlarged, dysfunctional HDL (high-density lipoprotein) particles contribute to the augmented atherosclerosis susceptibility associated with SR-BI (scavenger receptor BI) deficiency in mice. Approach and Results: We eliminated the ability of HDL particles to fully mature by targeting PLTP (phospholipid transfer protein) functionality. Particle size of the HDL population was almost fully normalized in male and female SR-BI×PLTP double knockout mice.

Low human and murine Mcl-1 expression leads to a pro-apoptotic plaque phenotype enriched in giant-cells.

The anti-apoptotic protein myeloid cell leukemia 1 (Mcl-1) plays an important role in survival and differentiation of leukocytes, more specifically of neutrophils. Here, we investigated the impact of myeloid Mcl-1 deletion in atherosclerosis. Western type diet fed LDL receptor-deficient mice were transplanted with either wild-type (WT) or LysMCre Mcl-1 (Mcl-1) bone marrow.

Peptide Antagonists for P-selectin Discriminate between Sulfatide-Dependent Platelet Aggregation and PSGL-1-Mediated Cell Adhesion.

Background: Membrane-exposed sulfatides are proposed to contribute to P-selectin-dependent platelet aggregation. Here, we demonstrated that P-selectin-mediated platelet aggregation on a collagen-coated surface under flow indeed depended on sulfatides and that this interaction differed considerably from the interaction of P-selectin with P-selectin Glycoprotein Ligand-1 (PSGL-1), which underlies leukocyte-endothelium adhesion.

Methods And Results: Upon platelet activation, sulfatides were translocated to the platelet surface to form focal hot-spots.

Evaluation of GalNAc-siRNA Conjugate Activity in Pre-clinical Animal Models with Reduced Asialoglycoprotein Receptor Expression.

The hepatocyte-specific asialoglycoprotein receptor (ASGPR) is an ideal candidate for targeted drug delivery to the liver due to its high capacity for substrate clearance from circulation together with its well-conserved expression and function across species. The development of GalNAc-siRNA conjugates, in which a synthetic triantennary N-acetylgalactosamine-based ligand is conjugated to chemically modified siRNA, has enabled efficient, ASGPR-mediated delivery to hepatocytes. To investigate the potential impact of variations in receptor expression on the efficiency of GalNAc-siRNA conjugate delivery, we evaluated the pharmacokinetics and pharmacodynamics of GalNAc-siRNA conjugates in multiple pre-clinical models with reduced receptor expression.

Leukocyte Bim deficiency does not impact atherogenesis in ldlr mice, despite a pronounced induction of autoimmune inflammation.

Proapoptotic Bcl-2 family member Bim is particularly relevant for deletion of autoreactive and activated T and B cells, implicating Bim in autoimmunity. As atherosclerosis is a chronic inflammatory process with features of autoimmune disease, we investigated the impact of hematopoietic Bim deficiency on plaque formation and parameters of plaque stability. Bim or wild type bone marrow transplanted ldlr mice were fed a Western type diet (WTD) for 5 or 10 weeks, after which they were immunophenotyped and atherosclerotic lesions were analyzed.

Hematopoietic arginase 1 deficiency results in decreased leukocytosis and increased foam cell formation but does not affect atherosclerosis.

Background And Aims: Arginase1 (Arg1), an M2 macrophage marker, plays a critical role in a number of immunological functions in macrophages, which are the main cell type facilitating atherosclerotic lesion development. Arg1 uses the substrate l-arginine to create l-ornithine, a precursor molecule required for collagen formation and vascular smooth muscle cell differentiation. By reducing l-arginine availability, Arg1 limits the production of nitric oxide (NO), a pro-atherogenic factor in macrophages.

Abca1 deficiency protects the heart against myocardial infarction-induced injury.

Background And Aims: We explored the role of ATP-binding cassette transporter A1 (Abca1), in post-myocardial infarction (MI) cardiac injury.

Methods: In Abca1(-/-) mice, wild type (WT) mice, and WT mice transplanted with Abca1(-/-) or WT bone marrow, an MI was induced in vivo. Furthermore, an ex vivo MI was induced in isolated Abca1(-/-) and WT hearts.

Hck/Fgr Kinase Deficiency Reduces Plaque Growth and Stability by Blunting Monocyte Recruitment and Intraplaque Motility.

Background: Leukocyte migration is critical for the infiltration of monocytes and accumulation of monocyte-derived macrophages in inflammation. Considering that Hck and Fgr are instrumental in this process, their impact on atherosclerosis and on lesion inflammation and stability was evaluated.

Methods And Results: Hematopoietic Hck/Fgr-deficient, LDLr(-/-) chimeras, obtained by bone marrow transplantation, had smaller but, paradoxically, less stable lesions with reduced macrophage content, overt cap thinning, and necrotic core expansion as the most prominent features.

Orp8 deficiency in bone marrow-derived cells reduces atherosclerotic lesion progression in LDL receptor knockout mice.

Introduction: Oxysterol binding protein Related Proteins (ORPs) mediate intracellular lipid transport and homeostatic regulation. ORP8 downregulates ABCA1 expression in macrophages and cellular cholesterol efflux to apolipoprotein A-I. In line, ORP8 knockout mice display increased amounts of HDL cholesterol in blood.

Diet-induced (epigenetic) changes in bone marrow augment atherosclerosis.

Alterations in DNA methylation patterns in peripheral blood leukocytes precede atherosclerotic lesion development in mouse models of atherosclerosis and have been linked to cardiovascular death in patients. The aim of this study is to investigate the long-term changes induced by WTD feeding on BM cells and the consequences for atherosclerosis susceptibility. Hereto, WTD BM or Chow BM was transplanted into LDLR KO mice on chow.

CXCR4 blockade induces atherosclerosis by affecting neutrophil function.

Aims: The SDF-1α/CXCR4 dyad was previously shown by us and others to be instrumental in intimal hyperplasia as well as early stage atherosclerosis. We here sought to investigate its impact on clinically relevant stages of atherosclerosis in mouse and man.

Methods And Results: Immunohistochemical analysis of CXCR4 expression in human atherosclerotic lesions revealed a progressive accumulation of CXCR4(+) cells during plaque progression.

Elimination of macrophages drives LXR-induced regression both in initial and advanced stages of atherosclerotic lesion development.

While numerous studies have aimed to develop strategies to inhibit the development and progression of atherosclerosis, recent attention has focussed on the regression of pre-existing atherosclerotic plaques. As important regulator of total body cholesterol homeostasis, the liver X receptor (LXR) could possibly be an important target to induce regression. Here, we describe the effect of LXR activation by the synthetic agonist T0901317 on lesion regression in different mouse models with early fatty streak lesions or advanced collagen-rich lesions.

Interruption of the OX40-OX40 ligand pathway in LDL receptor-deficient mice causes regression of atherosclerosis.

Patients suffering from cardiovascular disease have well-established atherosclerotic lesions, rendering lesion regression of therapeutic interest. The OX40 (TNFRSF4)-OX40 ligand (OX40L; TNFSF4) pathway is important for the proliferation and survival of T cells, stimulates B cells, and is associated with cardiovascular disease. We hypothesized that interference with the OX40-OX40L pathway, in combination with decreases in cholesterol, may induce regression of atherosclerosis.

Quaking, an RNA-binding protein, is a critical regulator of vascular smooth muscle cell phenotype.

Rationale: RNA-binding proteins are critical post-transcriptional regulators of RNA and can influence pre-mRNA splicing, RNA localization, and stability. The RNA-binding protein Quaking (QKI) is essential for embryonic blood vessel development. However, the role of QKI in the adult vasculature, and in particular in vascular smooth muscle cells (VSMCs), is currently unknown.

Identification of a novel CD40 ligand for targeted imaging of inflammatory plaques by phage display.

The CD40/CD40L dyad is deemed to play a central role in several inflammatory processes, including atherosclerosis. As CD40 is overexpressed in atherosclerotic lesions, it constitutes a promising candidate for targeted imaging approaches. Here we describe the design of a novel, selective peptide ligand for CD40 by phage display.

Scavenger receptor-AI-targeted iron oxide nanoparticles for in vivo MRI detection of atherosclerotic lesions.

Objective: In search of molecular imaging modalities for specific detection of inflammatory atherosclerotic plaques, we explored the potential of targeting scavenger receptor-AI (SR-AI), which is highly expressed by lesional macrophages and linked to effective internalization machinery.

Approach And Results: Ultrasmall superparamagnetic iron oxide particles were conjugated to a peptidic SR-AI ligand (0.371 mol Fe/L and 0.