Unstable Atherosclerotic Lesions Research Articles

Secreted Protein Profiling of Human Aortic Smooth Muscle Cells Identifies Vascular Disease Associations.

Smooth muscle cells (SMCs), which make up the medial layer of arteries, are key cell types involved in cardiovascular disease, the leading cause of mortality and morbidity worldwide. In response to microenvironment alterations, SMCs dedifferentiate from a contractile to a synthetic phenotype characterized by an increased proliferation, migration, production of ECM (extracellular matrix) components, and decreased expression of SMC-specific contractile markers. These phenotypic changes result in vascular remodeling and contribute to the pathogenesis of cardiovascular disease, including coronary artery disease, stroke, hypertension, and aortic aneurysms. Here, we aim to identify the genetic variants that regulate ECM secretion in SMCs and predict the causal proteins associated with vascular disease-related loci identified in genome-wide association studies. Using human aortic SMCs from 123 multiancestry healthy heart transplant donors, we collected the serum-free media in which the cells were cultured for 24 hours and conducted liquid chromatography-tandem mass spectrometry-based proteomic analysis of the conditioned media. We measured the abundance of 270 ECM and related proteins. Next, we performed protein quantitative trait locus mapping and identified 20 loci associated with secreted protein abundance in SMCs. We functionally annotated these loci using a colocalization approach. This approach prioritized the genetic variant rs6739323-A at the 2p22.3 locus, which is associated with lower expression of LTBP1 (latent-transforming growth factor beta-binding protein 1) in SMCs and atherosclerosis-prone areas of the aorta, and increased risk for SMC calcification. We found that LTBP1 expression is abundant in SMCs, and its expression at mRNA and protein levels was reduced in unstable and advanced atherosclerotic plaque lesions. Our results unravel the SMC proteome signature associated with vascular disorders, which may help identify potential therapeutic targets to accelerate the pathway to translation.

Small Molecule Activation of NAPE-PLD Enhances Efferocytosis by Macrophages.

N-Acyl-phosphatidylethanolamine hydrolyzing phospholipase D (NAPE-PLD) is a zinc metallohydrolase that hydrolyzes N-acyl-phosphatidylethanolamines (NAPEs) to form N-acyl-ethanolamines (NAEs) and phosphatidic acid. Several lines of evidence suggest that reduced NAPE-PLD activity could contribute to cardiometabolic diseases. For instance, NAPEPLD expression is reduced in human coronary arteries with unstable atherosclerotic lesions, defective efferocytosis is implicated in the enlargement of necrotic cores of these lesions, and NAPE-PLD products such as palmitoylethanolamide and oleoylethanolamide have been shown to enhance efferocytosis. Thus, enzyme activation mediated by a small molecule may serve as a therapeutic treatment for cardiometabolic diseases. As a proof-of-concept study, we sought to identify small molecule activators of NAPE-PLD. High-throughput screening followed by hit validation and primary lead optimization studies identified a series of benzothiazole phenylsulfonyl-piperidine carboxamides that variably increased activity of both mouse and human NAPE-PLD. From this set of small molecules, two NAPE-PLD activators (VU534 and VU533) were shown to increase efferocytosis by bone-marrow derived macrophages isolated from wild-type mice, while efferocytosis was significantly reduced in Napepld-/- BMDM or after Nape-pld inhibition. Together, these studies demonstrate an essential role for NAPE-PLD in the regulation of efferocytosis and the potential value of NAPE-PLD activators as a strategy to treat cardiometabolic diseases.

A cyclic azapeptide ligand of the scavenger receptor CD36/SR-B2 reduces the atherosclerotic lesion progression and enhances plaque stability in apolipoprotein E-deficient mice.

Atherosclerosis is a chronic inflammatory disease of the arterial walls that develops at predisposed sites. As a major risk factor for adverse cardiovascular pathology, atherosclerosis can progress to myocardial infarction and stroke, due to the rupture of unstable atherosclerotic lesions. Macrophage uptake of modified lipoproteins and metabolic dysfunction contributes significantly to the initiation and development of atherosclerotic lesions. The cluster of differentiation 36 receptor [CD36 (SR-B2)] plays a key role in atherosclerotic lesion progression and acts as an efferocytic molecule in the resolution of advanced plaque. In previous studies, linear azapeptide CD36 ligands were shown to exhibit anti-atherosclerotic properties. In the present study, a novel potent and selective macrocyclic azapeptide CD36 ligand, MPE-298, has proven effective in protecting against atherosclerosis progression. Features of greater plaque stability were observed after 8 weeks of daily injections with the cyclic azapeptide in apolipoprotein E-deficient mice fed a high-fat high-cholesterol diet.

Comparative morphometric analysis of contents mononuclear cells in unstable and in stable atherosclerotic lesions

BACKGROUND: Recent research results indicate that inflammatory cellular responses can play a significant role in the pathogenesis of atherosclerosis in humans and experimental animals, with a predominance in infiltrates of lymphocytes and monocytes/macrophages that contribute to destructive processes in the vascular wall. However, no comparative, differentiated morphometric analysis of the content of mononuclear cells in unstable and stable atherosclerotic lesions has been carried out so far.
 AIM: Carrying out comparative histological and morphometric examination of quantitative content of lymphocytes and macrophages in normal vascular wall, in lipid stain, in unstable and in stable atherosclerotic lesions.
 MATERIALS AND METHODS: The study material was samples taken during 15 autopsies aged 56 to 71 years who died from acute cardiovascular failure of atherosclerotic etiology. A comparative histological and morphometric study of the content of mononuclear cells: lymphocytes and macrophages in normal areas of the vascular wall, in lipid stains, in unstable and stable atherosclerotic lesions was carried out a total of 50 tissue samples stained with hematoxylin and eosin.
 RESULTS: A sharp increase in the content of studied cells in intima, atheromatous nucleus and adventition in unstable atherosclerotic plaques was revealed. In normal areas of the vascular wall, in initial atherosclerotic lesions and in stable plaques, the number of macrophages and lymphocytes is small.
 CONCLUSIONS: In general, the results obtained are well consistent with the literature and suggest in favor of the need for lymphocytes and macrophages to form immuno-inflammatory reactions in the formation of unstable atherosclerotic lesions in humans.

Therapeutic inhibition of MPO stabilizes pre-existing high risk atherosclerotic plaque

Currently there are no established therapies to treat high-risk patients with unstable atherosclerotic lesions that are prone to rupture and can result in thrombosis, abrupt arterial occlusion, and a precipitous infarction. Rather than being stenotic, rupture-prone non-occlusive plaques are commonly enriched with inflammatory cells and have a thin fibrous cap. We reported previously that inhibition of the pro-inflammatory enzyme myeloperoxidase (MPO) with the suicide inhibitor AZM198 prevents formation of unstable plaque in the Tandem Stenosis (TS) mouse model of plaque instability. However, in our previous study AZM198 was administered to animals before unstable plaque was present and hence it did not test the significant unmet clinical need present in high-risk patients with vulnerable atherosclerosis. In the present study we therefore asked whether pharmacological inhibition of MPO with AZM198 can stabilize pre-existing unstable lesions in an interventional setting using the mouse model of plaque instability. In vivo molecular magnetic resonance imaging of arterial MPO activity using bis-5-hydroxytryptamide-DTPA-Gd and histological analyses revealed that arterial MPO activity was elevated one week after TS surgery, prior to the presence of unstable lesions observed two weeks after TS surgery. Animals with pre-existing unstable plaque were treated with AZM198 for one or five weeks. Both short- and long-term intervention effectively inhibited arterial MPO activity and increased fibrous cap thickness, indicative of a more stable plaque phenotype. Plaque stabilization was observed without AZM198 affecting the arterial content of Ly6B.2+- and CD68+-cells and MPO protein. These findings demonstrate that inhibition of arterial MPO activity converts unstable into stable atherosclerotic lesions in a preclinical model of plaque instability and highlight the potential therapeutic potency of MPO inhibition for the management of high-risk patients and the development of novel protective strategies against cardiovascular diseases.

Abstract P3031: Highly Sensitive Impedance Microsensors Based On Graphene Quantum Dots For The Detection Of Metabolically Active Plaques In Animal Models

Detection of rupture-prone and unstable atherosclerotic lesions is of vital values for patients with acute coronary syndromes or stroke. Despite advances in diagnosis and therapy, sensing of metabolically active but angiographically invisible atherosclerotic lesions remains an unsatisfied clinical challenge but highly desirable. Graphene quantum dots (GQDs) have been widely studied in recent years due to its unique optical and electrical properties, thus providing a huge opportunity for building high-performance sensors. Herein, a highly sensitive impedance microsensor based on platinum nanoparticles (PtNPs) @GQDs was constructed for atherosclerotic lesions assessment, especially for the perception of metabolically active but angiographically invisible atherosclerotic lesions. We designed two-step procedures to prepare PtNPs@GQDs microsensors including electrochemical reduction of GQDs and subsequent electrochemical deposition of ultrafine PtNPs. Atherosclerotic lesions samples at mouse aorta and pig carotid confirm this microsensors with highly sensitive impedance signals and indicated possible atherosclerotic lesions. The equivalent circuits simulation suggested that synergetic PtNPs@GQDs creates more parallel conduction path, thus leading to highly sensitive impedance signals. Our studies offer a universal strategy to prepare high-performance impedance sensors and unique opportunities of translational medicine for early atherosclerotic disease detection and prevention of acute coronary syndromes and stroke.

Proteomic Characterization of Atherosclerotic Lesions In Situ Using Percutaneous Coronary Intervention Angioplasty Balloons—Brief Report

Materials extracted from atherosclerotic arteries can disclose data about the molecular pathology of cardiovascular disease, but obtaining such samples is complex and requires invasive surgery. To overcome this barrier, this study investigated whether angioplasty balloons inflated during standard percutaneous coronary interventions retain proteins from treated (dilated) atherosclerotic lesions and whether proteomic analysis of this material could provide data on lesion protein profiles and distinguish between patients with stable and unstable coronary artery disease. Patients with ST-segment-elevation myocardial infarction and stable angina pectoris were subjected to routine percutaneous coronary interventions. All angioplasty balloons inflated in a coronary artery were collected. Proteins retained on the balloons were extracted and analyzed using shotgun proteomic analysis. Proteomics identified and quantified 1365 unique proteins captured on percutaneous coronary intervention balloons. Control balloons inflated in the ascending aorta showed minimal nonspecific protein binding, indicating specificity to the luminal region of atherosclerotic lesions of the diseased artery wall. Clustering and principal component analyses showed that ST-segment-elevation myocardial infarction and stable angina pectoris subjects could be separated by variations in protein content and abundance. We identified 206 proteins as differentially abundant between ST-segment-elevation myocardial infarction and stable angina pectoris subjects. Pathway analysis indicated several enriched processes in the ST-segment-elevation myocardial infarction group involved in neutrophil-mediated immunity and platelet activation. Disease-related proteins from coronary artery lesions adhere to angioplasty balloons and constitute a source of material for proteomic analysis. This approach can identify proteins and processes occurring in unstable coronary atherosclerotic lesions and suggest novel therapeutic approaches.

Белок S100A8 в атеросклеротических поражениях у человека

Introduction. In the pathogenesis of atherosclerosis, a change in the content of different proteins in S100 protein family may play an important role in the formation of atherosclerotic lesions in the vascular wall. The aim was to study the content of mononuclear cells expressing protein S100A8 in different types of atherosclerotic lesions secondary to the development of the inflammatory process in the vascular wall during atherogenesis in humans. Materials and methods. Immunohistochemical and morphometric studies were performed on autopsy material (18 cases) obtained from patients who died from acute cardiovascular insufficiency of atherosclerotic etiology. We detected the expression of S100A8 protein in the aortic segments (from the arc, thoracic and abdominal regions), coronary arteries, and arteries of the circle of Willis (40 tissue samples) using a highly sensitive two-stage streptavidin-biotin method. Comparative analysis was subjected to normal areas of arteries, lipid stain, and unstable and stable atherosclerotic plaques. We performed a statistical analysis with the computer program Statistica Version 10. The significance of the differences between the samples studied was determined by the Student’s T-criterion. Results. Intracellular localization of S100A8 protein was found in the intima of unstable atherosclerotic lesions. Its expression was mainly concentrated in the cytoplasm of macrophages. Intracellular production of S100A8 was minimal or absent in normal areas of aorta intima, coronary arteries, a. basilaris, and in the cap of stable atherosclerotic plaques. We detected numerous inflammatory mononuclear cell infiltrates in the areas of the vascular wall with S100A8 expression. According to the morphometry, their content in the intima of unstable plaques significantly exceeded the similar rate in the intima of normal areas of arteries and stable lesions. Conclusion. We hypothesize that protein S100A8 may contribute to the activation of immune-inflammatory reactions in the vascular wall, which are the basis for the formation of unstable progressive atherosclerotic lesions leading to the development of acute coronary syndrome. Further research may provide more evidence to support that S100A8 proteins are a promising drug target in the prevention and therapy of atherosclerosis. Keywords: atherogenesis, S100A8 protein, unstable atherosclerotic plaque

Intravascular ultrasound insights into the unstable features of the coronary atherosclerotic plaques: A systematic review and meta‐analysis

There is a lack of a comprehensive picture of plaque geometry and composition of unstable atherosclerotic lesions as observed with intravascular ultrasound techniques. We analysed through a systematic review with meta-analysis 39 characteristics of atherosclerotic plaques in three scenarios involving culprit and non-culprit lesions from acute coronary syndromes vs stable angina pectoris patients, and culprit vs non-culprit lesions in acute coronary syndromes patients. A systematic search of PubMed and EMBASE, from inception to April 2020 was performed. The combined odds ratios or mean differences of all IVUS characteristics were calculated with random-effects models. Twenty-eight studies involving 5434 subjects, and 5618 lesions were included. Culprit lesions in acute coronary syndromes have larger plaque areas and remodeling indexes (MD=0.13 [0.08; 0.17], p<0.001) and contained larger necrotic cores (MD=0.67 (95% CI 0.19;1.15), p=0.006) that stable angina culprit lesions. In acute patients, culprit plaques were also more remodeled, had larger necrotic cores and had more frequently a Thin-Cap Fibroatheroma morphology (OR=1.79 (95% CI 1.21; 2.65), p=0.004) than non-culprit lesions. Non-culprit lesions in acute syndromes were more often ruptured (OR=2.25 (95% CI:1.05; 4.82), p=0.037) or Thin-Cap Fibroatheromas than in stable angina. Culprit lesions from acute coronary patients are larger, more positively remodeled and contained more lipids as compared to stable angina lesions or non-culprit in acute patients. Non culprit lesions are also more often complicated or vulnerable in acute than stable patients.

The role of neovascularization in the formation of an unstable human atherosclerotic plaque

The study material was 20 autopsy samples obtained from males aged 65 to 72 years who died from acute atherosclerotic cardiovascular insufficiency. Aortic segments (from the arch, thoracic and abdominal regions), coronary arteries and the arteries of the base of the brain (a. basilaris) were investigated; these totaled 45 tissue segments. Neovessels and cellular responses in the arterial wall were examined by hematoxylin and eosin staining. VEGF was immunohistochemically detected using a highly sensitive two-stage streptavidin-biotin method. In unstable atherosclerotic lesions, there were active neovascularization processes in both the fibrous cap and the underlying parts of the adventitia. These changes are usually combined with a pronounced cellular inflammatory response that can contribute to their development. Endothelial growth factor may be one of the causes of neovascularization in unstable atherosclerotic lesions. A comparative immunomorphological study in the human aorta, coronary arteries, and a. basilaris revealed active neovascularization processes in the cap and the underlying parts of the adventitia in unstable atherosclerotic lesions. The cause of this neovascularization is probably endothelial growth factor and cellular inflammatory responses.

Inflammation of carotid plaques and risk of cerebrovascular events.

Carotid atherosclerotic plaques represent a risk for ischemic stroke. The data indicate that the risk for distal embolization from atherosclerotic lesions in internal carotid arteries is not related only to the degree of stenosis but also to the composition of plaques. The stability of atherosclerotic plaque depends on the thickness of the fibrous cap and plaque hemorrhage. Recent research indicated that the inflammatory activity of atherosclerotic lesions is pivotal in the progression of atherosclerotic plaques. It also promotes the development of unstable atherosclerotic lesions and is related to thromboembolic cerebrovascular complications. Inflammation destabilizes atherosclerotic plaques through the degradation of their fibrotic structure. Inflammation of atherosclerotic plaques was confirmed by histopathologic findings and levels of circulating inflammatory markers which were correlated to the intensity of the inflammation in atherosclerotic lesions. Recently, new techniques like fluorodeoxyglucose positron emission tomography (18-FDG PET) were developed for the identification of inflammation of atherosclerotic lesions in the vessel wall in vivo. Systemic inflammatory markers, particularly interleukins, tumor necrosis factor-alpha and metalloproteinases were shown to be related to the intensity of the inflammatory process in atherosclerotic lesions and the cerebrovascular events. Identification of inflamed atherosclerotic plaques may help to identify unstable atherosclerotic lesions and subjects at high risk for cerebrovascular incidents who need intensive preventive measures including anti-inflammatory medication.

Evaluation of Some Coagulation Profile and Estimation of Fibrinogen Level in Sudanese Patients with Type II Diabetes Mellitus

BACKGROUND: Type II diabetes, fibrinogen levels have been demonstrated to predict the progression to overt nephropathy. Hyperfibrinogenemia, an indicator of inflammation, is also associated with the presence of endothelial dysfunction, insulin resistance, hypercoagulability, and increased blood viscosity and is a marker of unstable atherosclerotic lesions. AIM: This study aimed to evaluation of coagulation profile and D-dimer and estimation of Serum Fibrinogen Level in Sudanese Patients with type II Diabetes Mellitus in Khartoum State. METHODS: A questionnaire was designed to collect information about the study group, Blood sample were collected from all participants in Tri sodium citrate containers. Automated coagulometer (COATRON M1) was used to evaluate prothrombine time and activated partial thromboplastine time and measure fibrinogen level. D-dimer levels were evaluated using (ichroma™) Reader fluorescence scanning instrument an integrated Point of Care Test (POCT) system. RESULTS: The study showed that the mean and standard of PT, APTT, INR was (17.9 ± 3.8 sec, 32.6 ± 4.1 sec, 1.1 ± 0.3 respectively), the mean of age among study group was (53 ± 14.2 years), there was significant different when correlate PT and management of disease (p. value 0.01) . the present study show insignificant correlation between PT and treatment, complication and gender (0.20 , 0.13 and 0.08) respectively while APTT there was significant difference with management ,complication and gender p. value was (0.01 , 0.03 and 0.01 respectively) .The mean ± SD of fibrinogen level was 136 ± 20.7 ,the mean ± SD of fibrinogen level in male was 137.4 ± 20.6mg/dl and in female was 135.22 ± 20.9 mg/dl. The present study show the insignificant correlation among gender p-value was (0.594). The frequency of duration of disease in group less than 5 years was (34%), in 5-10 years was (41%) and in group more than 10 years was (25%). Statistically insignificant differences between fibrinogen level and duration of disease were observed p-value (0.776), there was insignificant difference between fibrinogen level and different age group p. value (0.66). The mean of D-dimer levels is (1309.3 ± 324.1mg /ml). CONCLUSION: The present study show that shortened prothrombin time, activated partial thromboplastin time, shortened PT and APTT might be useful haemostatic markers in diabetic patients, especially in those at high risk for thrombotic complications. The Mean of plasma fibrinogen level in patient with type II diabetics mellitus were136.3mg/dl, insignificant correlation with Fibrinogen levels with age, gender and duration of disease. The D. Dimer level show significant increase.

Comparative immunohistochemical and morphometric research of interleukin-17 in various atherosclerotic lesions in human

The aim of the artical to investigate cellular and tissue localization of IL-17 in various atherosclerotic lesions of arteries of human and on the basis of the obtained data to make a hypothesis of a possible role of Th17 of cells in destabilization of an atherosclerotic plaque.&#x0D; Material and methods. On autopsy material by means of histologic, immunohistochemical and morphometric research techniques aorta segments, the coronary arteries and a. basilaris with various types of atherosclerotic lesions (43 samples of tissue) were studied. In samples of tissue studied the endothelial and mononuclear cells expressing IL-17.&#x0D; Results. It is shown that endothelial cells of an intima are capable to produce IL-17 in all types of atherosclerotic plaques. Increase in number of the mononuclear cells expressing IL-17 in an intima of arteries was at the same time revealed. It is shown that the maximum number of the cells expressing IL-17 was found in an intima of an unstable atherosclerotic plaque, it is especially frequent around a rupture of its cap. What can demonstrate pro-inflammatory action of Th17-cells and IL-17 expressed by them and significant effect them on formation of unstable atherosclerotic lesions.&#x0D; Conclusion. On the basis of the obtained data for the first time it was succeeded to make a hypothesis of a possible role of Th-17 of cells in destabilization of an atherosclerotic plaque.

Functional ability of neutrophils in patients with ischemic heart disease

Purpose. The study of protein-producing and lipid-releasing ability of neutrophils and its clinical significance in patients with IHD.Materials and methods. 25 patients with arterial hypertension without clinical and ultrasound manifestations of atherosclerosis were examined; 47 patients with coronary artery disease with stable angina, as well as 19 patients with unstable primary angina. The comparison group — 33 healthy persons. In the serum, enzyme-linked immunosorbent assay was used to evaluate the concentration of C-reactive protein (CRP), lipoprotein a (LPa), VII coagulation factor VII (VIIf), defensins-alpha (1–3), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor alpha (TNF-alpha). Leukocytes, predominantly represented by neutrophils, which were further cultivated, were excreted from peripheral blood in the presence of dextrans; the levels of CRP, LPa, defensins-alpha (1–3), VIIf, and lipid-releasing ability of leukocytes (LRAL) were assessed according to the method of A. V. Tuev and V. Yu. Mishlanov. An angiographic study, duplex scanning arteries, and echocardiography were performed.Results. It has been established that in patients at the stage of preclinical atherosclerotic lesion, the ability of leukocytes to form protein-lipid complexes (PLC), marked by LRAL, practically does not differ from healthy individuals, but already at this stage of atherogenesis an increase in their ability to produce antimicrobial peptides — defensins-alpha (1–3). In patients with coronary artery disease with stable angina pectoris, an increase in leukocyte production of a wide range of proteins — defensins-alpha (1–3), VIIf, LPA and CRP in combination with signs of a systemic inflammatory reaction, marked by high concentrations of CRP, interleukin-6 and tumor necrosis factor alpha in serum, was noticed. At this stage of atherogenesis, the value of LRAL is significantly different from the values of healthy individuals. It is shown that the higher the LRAL value, the higher the functional class of chronic heart failure in these patients (R = 0.4; p = 0.02). In patients with coronary artery disease with primary unstable angina, the maximum LRAL value was detected, and in patients with ultrasound signs of plaque instability, high concentrations of CRP in neutrophilic supernatants were found. Correlation analysis revealed that, in patients with coronary artery disease, the average percentage of coronary artery stenosis, according to angiography, is directly related to the LRAL value (R = 0.7; p = 0.03) and the serum concentration of TNF-alpha (R = 0.5; p = 0.03), and the number of clinically significant stenoses — with the magnitude of LRAL (R = 0.4; p = 0.04) and the concentration in supernatants VIIf (R = 0.5; p = 0.04).Conclusion. The LRAL value, CRP and defensin-alpha content in leukocyte supernatants in IHD patients are interconnected with the severity and activity of atherosclerotic lesion of arteries, which is confirmed by the results of examination of patients at the stage of preclinical, clinically manifest stable and unstable atherosclerotic lesion.

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-1fl/fl (Mcl-1−/−) bone marrow. Mcl-1 myeloid deletion resulted in enhanced apoptosis and lipid accumulation in atherosclerotic plaques. In vitro, Mcl-1 deficient macrophages also showed increased lipid accumulation, resulting in increased sensitivity to lipid-induced cell death. However, plaque size, necrotic core and macrophage content were similar in Mcl-1−/− compared to WT mice, most likely due to decreased circulating and plaque-residing neutrophils. Interestingly, Mcl-1−/− peritoneal foam cells formed up to 45% more multinucleated giant cells (MGCs) in vitro compared to WT, which concurred with an increased MGC presence in atherosclerotic lesions of Mcl-1−/− mice. Moreover, analysis of human unstable atherosclerotic lesions also revealed a significant inverse correlation between MGC lesion content and Mcl-1 gene expression, coinciding with the mouse data. Taken together, these findings suggest that myeloid Mcl-1 deletion leads to a more apoptotic, lipid and MGC-enriched phenotype. These potentially pro-atherogenic effects are however counteracted by neutropenia in circulation and plaque.

P1217Zirconium-89 labelled probe for molecular imaging of inflammation in experimental atherosclerosis

Abstract Background Early detection of inflamed atherosclerotic lesions by molecular imaging might improve risk assessment beyond that of vascular stenosis and plaque morphology imaging, and improve the clinical management of high-risk patients. Purpose To target the key features of unstable atherosclerotic lesions, we studied the feasibility of our radiotracer, based on modified human serum albumin (HSA), to identify inflamed atherosclerotic lesions by in vivo molecular imaging. Methods We applied a maleylated HSA (Mal-HSA) probe, recognised by scavenger receptors on macrophages, in an experimental in vivo imaging study of atherosclerosis. Mal-HSA was coupled with a positron-emittingmetal ion, Zirconium-89 (89Zr). The targeting potential of this probe was evaluated and compared with unspecific 89Zr-HSA and 18F-FDG in a mouse model of atherosclerosis (Apoe−/−, n=22) and compared with wild-type (WT) mice (C57BL/6, n=21) as controls. Radiotracer accumulation in the aortic arch was analysed in vivo by the fusion of positron emission tomography–magnetic resonance imaging (PET-MRI), radiotracer bio-distribution was measured ex vivo by gamma counter, and plaque uptake was evaluated by phosphor imaging (PI) autoradiography (ARG). Results PET-MRI, gamma counter measurements, and PI-ARG showed the accumulation of 89Zr-Mal-HSA in the atherosclerotic lesions of Apoe−/− mice. The maximum standardised uptake value (SUVmax) for 89Zr-Mal-HSA at 16 and 20 weeks were 26% and 20% higher (P&lt;0.05) in Apoe−/− mice than control WT mice, whereas no difference in SUVmax was found for 18F-FDG in the same animals. 89Zr-Mal-HSA uptake in the aorta as evaluated by gamma counter 48 h post-injection was 32% higher (P&lt;0.01) for Apoe−/− mice compared to WT mice, and the aorta-to-blood ratio was 10-fold higher (P&lt;0.001) for 89Zr-Mal-HSA compared with unspecific 89Zr-HSA. HSA probes were mainly distributed to the liver, spleen, kidneys, bone and lymph nodes. The PI-ARG results corroborated the PET and gamma counter measurements, showing higher accumulation of 89Zr-Mal-HSA in the aortas of Apoe−/− mice compared to WT mice; 9.4±1.4 vs 0.8±0.3% (P&lt;0.001). Conclusions The modified HSA-based radiotracer showed in vivo targeting of inflamed atherosclerotic lesions of mouse aorta, which could also be verified ex vivo. 89Zr-Mal-HSA seems to be a promising diagnostic tool for the identification of vascular inflammation. Further methodological studies are needed to verify its applicability for detecting rupture-prone plaques. Acknowledgement/Funding Swedish Research Council (22036); the Swedish HLF (20150423, 20170669); ALF (20150517, 447561, 726481); Söderberg Foundations, VINNOVA and KI

Human serum albumin-based probes for molecular targeting of macrophage scavenger receptors.

Background: Inflammation and accumulation of macrophages are key features of unstable atherosclerotic plaques. The ability of macrophages to take up molecular probes can be exploited in new clinical imaging methods for the detection of unstable atherosclerotic lesions. We investigated whether modifications of human serum albumin (HSA) could be used to target macrophages efficiently in vitro.Materials and methods: Maleylated and aconitylated HSA were compared with unmodified HSA. Fluorescent or radiolabeled (89Zr) modified HSA was used in in vitro experiments to study cellular uptake by differentiated THP-1 cells and primary human macrophages. The time course of uptake was evaluated by flow cytometry, confocal microscopy, real-time microscopy and radioactivity measurements. The involvement of scavenger receptors (SR-A1, SR-B2, LOX-1) was assessed by knockdown experiments using RNA interference, by blocking experiments and by assays of competition by modified low-density lipoprotein.Results: Modified HSA was readily taken up by different macrophages. Uptake was mediated nonexclusively via the scavenger receptor SR-A1 (encoded by the MSR1 gene). Knockdown of CD36 and ORL1 had no influence on the uptake. Modified HSA was preferentially taken up by human macrophages compared with other vascular cell types such as endothelial cells and smooth muscle cells.Conclusions: Modified 89Zr-labeled HSA probes were recognized by different subsets of polarized macrophages, and maleylated HSA may be a promising radiotracer for radionuclide imaging of macrophage-rich inflammatory vascular diseases.

Myeloid Slc2a1-Deficient Murine Model Revealed Macrophage Activation and Metabolic Phenotype Are Fueled by GLUT1.

Macrophages (MΦs) are heterogeneous and metabolically flexible, with metabolism strongly affecting immune activation. A classic response to proinflammatory activation is increased flux through glycolysis with a downregulation of oxidative metabolism, whereas alternative activation is primarily oxidative, which begs the question of whether targeting glucose metabolism is a viable approach to control MΦ activation. We created a murine model of myeloid-specific glucose transporter GLUT1 (Slc2a1) deletion. Bone marrow-derived MΦs (BMDM) from Slc2a1M-/- mice failed to uptake glucose and demonstrated reduced glycolysis and pentose phosphate pathway activity. Activated BMDMs displayed elevated metabolism of oleate and glutamine, yet maximal respiratory capacity was blunted in MΦ lacking GLUT1, demonstrating an incomplete metabolic reprogramming. Slc2a1M-/- BMDMs displayed a mixed inflammatory phenotype with reductions of the classically activated pro- and anti-inflammatory markers, yet less oxidative stress. Slc2a1M-/- BMDMs had reduced proinflammatory metabolites, whereas metabolites indicative of alternative activation-such as ornithine and polyamines-were greatly elevated in the absence of GLUT1. Adipose tissue MΦs of lean Slc2a1M-/- mice had increased alternative M2-like activation marker mannose receptor CD206, yet lack of GLUT1 was not a critical mediator in the development of obesity-associated metabolic dysregulation. However, Ldlr-/- mice lacking myeloid GLUT1 developed unstable atherosclerotic lesions. Defective phagocytic capacity in Slc2a1M-/- BMDMs may have contributed to unstable atheroma formation. Together, our findings suggest that although lack of GLUT1 blunted glycolysis and the pentose phosphate pathway, MΦ were metabolically flexible enough that inflammatory cytokine release was not dramatically regulated, yet phagocytic defects hindered MΦ function in chronic diseases.

Chronic sympathetic driven hypertension promotes atherosclerosis by enhancing hematopoiesis

Hypertension is a major, independent risk factor for atherosclerotic cardiovascular disease. However, this pathology can arise through multiple pathways, which could influence vascular disease through distinct mechanisms. An overactive sympathetic nervous system is a dominant pathway that can precipitate in elevated blood pressure. We aimed to determine how the sympathetic nervous system directly promotes atherosclerosis in the setting of hypertension. We used a mouse model of sympathetic nervous system-driven hypertension on the atherosclerotic-prone apolipoprotein E-deficient background. When mice were placed on a western type diet for 16 weeks, we showed the evolution of unstable atherosclerotic lesions. Fortuitously, the changes in lesion composition were independent of endothelial dysfunction, allowing for the discovery of alternative mechanisms. With the use of flow cytometry and bone marrow imaging, we found that sympathetic activation caused deterioration of the hematopoietic stem and progenitor cell niche in the bone marrow, promoting the liberation of these cells into the circulation and extramedullary hematopoiesis in the spleen. Specifically, sympathetic activation reduced the abundance of key hematopoietic stem and progenitor cell niche cells, sinusoidal endothelial cells and osteoblasts. Additionally, sympathetic bone marrow activity prompted neutrophils to secrete proteases to cleave the hematopoietic stem and progenitor cell surface receptor CXCR4. All these effects could be reversed using the β-blocker propranolol during the feeding period. These findings suggest that elevated blood pressure driven by the sympathetic nervous system can influence mechanisms that modulate the hematopoietic system to promote atherosclerosis and contribute to cardiovascular events.

Novel Multiomics Profiling of Human Carotid Atherosclerotic Plaques and Plasma Reveals Biliverdin Reductase B as a Marker of Intraplaque Hemorrhage

Clinical tools to identify individuals with unstable atherosclerotic lesions are required to improve prevention of myocardial infarction and ischemic stroke. Here, a systems-based analysis of atherosclerotic plaques and plasma from patients undergoing carotid endarterectomy for stroke prevention was used to identify molecular signatures with a causal relationship to disease. Local plasma collected in the lesion proximity following clamping prior to arteriotomy was profiled together with matched peripheral plasma. This translational workflow identified biliverdin reductase B as a novel marker of intraplaque hemorrhage and unstable carotid atherosclerosis, which should be investigated as a potential predictive biomarker for cardiovascular events in larger cohorts.