Lowering Low-Density Lipoprotein Particles in Plasma Using Dextran Sulphate Co-Precipitates Procoagulant Extracellular Vesicles

Plasma extracellular vesicles (EVs) are lipid membrane vesicles involved in several biological processes including coagulation. Both coagulation and lipid metabolism are strongly associated with cardiovascular events. Lowering very-low- and low-density lipoprotein ((V)LDL) particles via dextran sulphate LDL apheresis also removes coagulation proteins. It remains unknown, however, how coagulation proteins are removed in apheresis. We hypothesize that plasma EVs that contain high levels of coagulation proteins are concomitantly removed with (V)LDL particles by dextran sulphate apheresis. For this, we precipitated (V)LDL particles from human plasma with dextran sulphate and analyzed the abundance of coagulation proteins and EVs in the precipitate. Coagulation pathway proteins, as demonstrated by proteomics and a bead-based immunoassay, were over-represented in the (V)LDL precipitate. In this precipitate, both bilayer EVs and monolayer (V)LDL particles were observed by electron microscopy. Separation of EVs from (V)LDL particles using density gradient centrifugation revealed that almost all coagulation proteins were present in the EVs and not in the (V)LDL particles. These EVs also showed a strong procoagulant activity. Our study suggests that dextran sulphate used in LDL apheresis may remove procoagulant EVs concomitantly with (V)LDL particles, leading to a loss of coagulation proteins from the blood

Inhibition of PFKFB3 Hampers the Progression of Atherosclerosis and Promotes Plaque Stability

Aims: 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB)3-mediated glycolysis is pivotal in driving macrophage- and endothelial cell activation and thereby inflammation. Once activated, these cells play a crucial role in the progression of atherosclerosis. Here, we analyzed the expression of PFKFB3 in human atherosclerotic lesions and investigated the therapeutic potential of pharmacological inhibition of PFKFB3 in experimental atherosclerosis by using the glycolytic inhibitor PFK158. Methods and Results: PFKFB3 expression was higher in vulnerable human atheromatous carotid plaques when compared to stable fibrous plaques and predominantly expressed in plaque macrophages and endothelial cells. Analysis of advanced plaques of human coronary arteries revealed a positive correlation of PFKFB3 expression with necrotic core area. To further investigate the role of PFKFB3 in atherosclerotic disease progression, we treated 6–8 weeks old male Ldlr–/– mice. These mice were fed a high cholesterol diet for 13 weeks, of which they were treated for 5 weeks with the glycolytic inhibitor PFK158 to block PFKFB3 activity. The incidence of fibrous cap atheroma (advanced plaques) was reduced in PFK158-treated mice. Plaque phenotype altered markedly as both necrotic core area and intraplaque apoptosis decreased. This coincided with thickening of the fibrous cap and increased plaque stability after PFK158 treatment. Concomitantly, we observed a decrease in glycolysis in peripheral blood mononuclear cells compared to the untreated group, which alludes that changes in the intracellular metabolism of monocyte and macrophages is advantageous for plaque stabilization. Conclusion: High PFKFB3 expression is associated with vulnerable atheromatous human carotid and coronary plaques. In mice, high PFKFB3 expression is also associated with a vulnerable plaque phenotype, whereas inhibition of PFKFB3 activity leads to plaque stabilization. This data implies that inhibition of inducible glycolysis may reduce inflammation, which has the ability to subsequently attenuate atherogenesis

Carotid atherosclerotic plaque matrix metalloproteinase-12-positive macrophage subpopulation predicts adverse outcome after endarterectomy

BACKGROUND: Matrix metalloproteinase-12 (MMP-12) promotes atherosclerosis in animal models. MMP-12 is expressed in only a subset of foam-cell macrophages (FCMs) in human plaques. We investigated whether the prevalence of this MMP-12–expressing subpopulation is a prognostic indicator of adverse outcome in patients after carotid endarterectomy (CEA). METHODS AND RESULTS: Serial sections of culprit lesions from 236 patients who underwent CEA and had undergone 3 years of clinical follow-up were stained immunocytochemically for MMP-12 and for CD68, and the MMP-12/CD68 ratio was used to quantify the MMP-12–expressing subpopulation. A high MMP-12/CD68 ratio correlated with a high content of lipid and total macrophages and a low content of vascular smooth muscle cells, as well as with MMP-8 (R=0.211, P=0.001), MMP-9 (R=0.251, P<0.001), and cleaved caspase-3 (R=0.142, P=0.036) activity measured in a neighboring segment. Dual immunohistochemical examination confirmed the location of MMP-12 in a subpopulation of MMP-8– and MMP-9–positive FCMs, whereas all apoptotic FCMs were MMP-12 positive. Patients who yielded plaques within the highest quartile compared with the lowest quartile of MMP-12/CD68 ratio had a 2.4-fold (hazard ratio, 2.4; 95% CI, 1.1- to 5.1-fold; adjusted P=0.027) increased risk of major adverse cardiovascular event and a 3.4-fold (3.4; 1.2- to 9.6-fold, P=0.024) increased risk for stroke. CONCLUSIONS: The prevalence of an MMP-12–positive subset of FCMs is a prognostic marker for adverse clinical outcome after CEA

Delayed Development of Aneurysmal Dilatations in Patients with Extracranial Carotid Artery Dissections

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Identification of CD163 as an antiinflammatory receptor for HMGB1-haptoglobin complexes

Secreted by activated cells or passively released by damaged cells, extracellular HMGB1 is a prototypical damage-associated molecular pattern (DAMP) inflammatory mediator. During the course of developing extracorporeal approaches to treating injury and infection, we inadvertently discovered that haptoglobin, the acute phase protein that binds extracellular hemoglobin and targets cellular uptake through CD163, also binds HMGB1. Haptoglobin-HMGB1 complexes elicit the production of antiinflammatory enzymes (heme oxygenase-1) and cytokines (e.g., IL-10) in WT but not in CD163-deficient macrophages. Genetic disruption of haptoglobin or CD163 expression significantly enhances mortality rates in standardized models of intra-abdominal sepsis in mice. Administration of haptoglobin to WT and to haptoglobin gene-deficient animals confers significant protection. These findings reveal a mechanism for haptoglobin modulation of the inflammatory action of HMGB1, with significant implications for developing experimental strategies targeting HMGB1-dependent inflammatory diseases

Leukocytic Toll-Like Receptor 2 Deficiency Preserves Cardiac Function And Reduces Fibrosis In Sustained Pressure Overload

An involement of Toll-like receptor 2 (TLR2) has been established in cardiac dysfunction after acute myocardial infarction; however, its role in chronic pressure overload is unclear. We sought to evaluate the role of TLR2 in cardiac hypertrophy, fibrosis and dysfunction in sustained pressure overload. We induced pressure overload via transverse aortic constriction (TAC) in TLR2-/- and wild type (WT) mice, and followed temporal changes over 8 weeks. Despite similar increases in heart weight, left ventricular (LV) ejection fraction (EF) and diastolic function (mitral E/A ratio) were preserved in TLR2-/- mice but impaired in WT mice following TAC. TAC produced less LV fibrosis in TLR2-/- mice associated with lower mRNA levels of collagen genes (Col1a1 and Col3a1) and lower protein level of TGFbeta1, compared to WT mice. Following TAC, the influx of macrophages and CD3 T cells into LV was similar between TLR2-/- and WT mice, whereas levels of cyto/chemokines were lower in the heart and plasma in TLR2-/- mice. TLR2-/- bone marrow-derived cells protected against LVEF decline and fibrosis following TAC. Our findings show that leukocytic TLR2 deficiency protects against LV dysfunction and fibrosis probably via a reduction in inflammatory signaling in sustained pressure overload

Caveolin-1 Influences Vascular Protease Activity and Is a Potential Stabilizing Factor in Human Atherosclerotic Disease

Caveolin-1 (Cav-1) is a regulatory protein of the arterial wall, but its role in human atherosclerosis remains unknown. We have studied the relationships between Cav-1 abundance, atherosclerotic plaque characteristics and clinical manisfestations of atherosclerotic disease.We determined Cav-1 expression by western blotting in atherosclerotic plaques harvested from 378 subjects that underwent carotid endarterectomy. Cav-1 levels were significantly lower in carotid plaques than non-atherosclerotic vascular specimens. Low Cav-1 expression was associated with features of plaque instability such as large lipid core, thrombus formation, macrophage infiltration, high IL-6, IL-8 levels and elevated MMP-9 activity. Clinically, a down-regulation of Cav-1 was observed in plaques obtained from men, patients with a history of myocardial infarction and restenotic lesions. Cav-1 levels above the median were associated with absence of new vascular events within 30 days after surgery [0% vs. 4%] and a trend towards lower incidence of new cardiovascular events during longer follow-up. Consistent with these clinical data, Cav-1 null mice revealed elevated intimal hyperplasia response following arterial injury that was significantly attenuated after MMP inhibition. Recombinant peptides mimicking Cav-1 scaffolding domain (Cavtratin) reduced gelatinase activity in cultured porcine arteries and impaired MMP-9 activity and COX-2 in LPS-challenged macrophages. Administration of Cavtratin strongly impaired flow-induced expansive remodeling in mice.This is the first study that identifies Cav-1 as a novel potential stabilizing factor in human atherosclerosis. Our findings support the hypothesis that local down-regulation of Cav-1 in atherosclerotic lesions contributes to plaque formation and/or instability accelerating the occurrence of adverse clinical outcomes. Therefore, given the large number of patients studied, we believe that Cav-1 may be considered as a novel target in the prevention of human atherosclerotic disease and the loss of Cav-1 may be a novel biomarker of vulnerable plaque with prognostic value

Human Validation of Genes Associated With a Murine Atherosclerotic Phenotype

ObjectiveThe genetically modified mouse is the most commonly used animal model for studying the pathogenesis of atherosclerotic disease. We aimed to assess if mice atherosclerosis-related genes could be validated in human disease through examination of results from genome-wide association studies. Approach and ResultsWe performed a systematic review to identify atherosclerosis-causing genes in mice and carried out gene-based association tests of their human orthologs for an association with human coronary artery disease and human large artery ischemic stroke. Moreover, we investigated the association of these genes with human atherosclerotic plaque characteristics. In addition, we assessed the presence of tissue-specific cis-acting expression quantitative trait loci for these genes in humans. Finally, using pathway analyses we show that the putative atherosclerosis-causing genes revealed few associations with human coronary artery disease, large artery ischemic stroke, or atherosclerotic plaque characteristics, despite the fact that the majority of these genes have cis-acting expression quantitative trait loci. ConclusionsA role for genes that has been observed in mice for atherosclerotic lesion development could scarcely be confirmed by studying associations of disease development with common human genetic variants. The value of murine atherosclerotic models for selection of therapeutic targets in human disease remains unclear

Titin-truncating variants affect heart function in disease cohorts and the general population

Titin-truncating variants (TTNtv) commonly cause dilated cardiomyopathy (DCM). TTNtv are also encountered in ~1% of the general population, where they may be silent, perhaps reflecting allelic factors. To better understand TTNtv, we integrated TTN allelic series, cardiac imaging and genomic data in humans and studied rat models with disparate TTNtv. In patients with DCM, TTNtv throughout titin were significantly associated with DCM. Ribosomal profiling in rat showed the translational footprint of premature stop codons in Ttn, TTNtv-position-independent nonsense-mediated degradation of the mutant allele and a signature of perturbed cardiac metabolism. Heart physiology in rats with TTNtv was unremarkable at baseline but became impaired during cardiac stress. In healthy humans, machine-learning-based analysis of high-resolution cardiac imaging showed TTNtv to be associated with eccentric cardiac remodeling. These data show that TTNtv have molecular and physiological effects on the heart across species, with a continuum of expressivity in health and disease

Implicating genes, pleiotropy, and sexual dimorphism at blood lipid loci through multi-ancestry meta-analysis

Publisher Copyright: © 2022, The Author(s).Background: Genetic variants within nearly 1000 loci are known to contribute to modulation of blood lipid levels. However, the biological pathways underlying these associations are frequently unknown, limiting understanding of these findings and hindering downstream translational efforts such as drug target discovery. Results: To expand our understanding of the underlying biological pathways and mechanisms controlling blood lipid levels, we leverage a large multi-ancestry meta-analysis (N = 1,654,960) of blood lipids to prioritize putative causal genes for 2286 lipid associations using six gene prediction approaches. Using phenome-wide association (PheWAS) scans, we identify relationships of genetically predicted lipid levels to other diseases and conditions. We confirm known pleiotropic associations with cardiovascular phenotypes and determine novel associations, notably with cholelithiasis risk. We perform sex-stratified GWAS meta-analysis of lipid levels and show that 3–5% of autosomal lipid-associated loci demonstrate sex-biased effects. Finally, we report 21 novel lipid loci identified on the X chromosome. Many of the sex-biased autosomal and X chromosome lipid loci show pleiotropic associations with sex hormones, emphasizing the role of hormone regulation in lipid metabolism. Conclusions: Taken together, our findings provide insights into the biological mechanisms through which associated variants lead to altered lipid levels and potentially cardiovascular disease risk.Peer reviewe