Vulnerable Atherosclerotic Lesions Research Articles

Proteomic profiling reveals higher presence of glycolytic enzymes in vulnerable atherosclerotic lesions

Proteomic profiling reveals higher presence of glycolytic enzymes in vulnerable atherosclerotic lesions

Proteomic profiling reveals higher presence of glycolytic enzymes in vulnerable atherosclerotic lesions

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Leducq PlaqOmics Background Our definition of vulnerable plaques is predominantly driven by histological analysis. The molecular mechanisms behind the vulnerable histological characteristics are not fully understood. Here we use mass spectrometry-based proteomics data, to identify molecular mechanisms linked to vulnerable plaques. Methods Atherosclerotic lesions from two hundred patients undergoing endarterectomy surgery were collected (149 male and 51 female plaques). From a total of two hundred plaque samples, extracellular matrix proteins were extracted and processed for untargeted proteomics analysis. The resulting protein levels were linked to existing histological characteristics, transcriptomic, and clinical data. Results We detected 1499 proteins in atherosclerotic lesions, which were mostly affiliated with biological processes including extracellular matrix organization, coagulation, and peptidase activity. Linear regression identified 240 proteins associated with plaque vulnerability index (a semi-quantitative score summarizing the presence of SMC cells, macrophages, plaque hemorrhage, and fat in the plaque). Among the proteins associated with high plaque vulnerability index we identified an overrepresentation of enzymes involved in glycolysis – including the rate limiting enzymes HK3 (beta =0.40 p =0.003) and PKM (beta =0.19 p =0.009). This was driven by macrophage numbers and fat content in the plaque. Furthermore, data from a validation cohort of 120 patients from the Medical University of Vienna, Austria, revealed that HK3 and PKM were associated with plaque progression (p =<0.001, p =0.017) and clinical symptoms (p = <0.001, p = <0.001). Conclusion Enzymes involved in the glycolysis process show higher presence in vulnerable plaques. This suggests an important role for energy metabolism in plaque vulnerability.

Vulnerable Atherosclerotic Plaque: Is There a Molecular Signature?

Atherosclerosis and its clinical manifestations, coronary and cerebral artery diseases, are the most common cause of death worldwide. The main pathophysiological mechanism for these complications is the rupture of vulnerable atherosclerotic plaques and subsequent thrombosis. Pathological studies of the vulnerable lesions showed that more frequently, plaques rich in lipids and with a high level of inflammation, responsible for mild or moderate stenosis, are more prone to rupture, leading to acute events. Identifying the vulnerable plaques helps to stratify patients at risk of developing acute vascular events. Traditional imaging methods based on plaque appearance and size are not reliable in prediction the risk of rupture. Intravascular imaging is a novel technique able to identify vulnerable lesions, but it is invasive and an operator-dependent technique. This review aims to summarize the current data from literature regarding the main biomarkers involved in the attempt to diagnose vulnerable atherosclerotic lesions. These biomarkers could be the base for risk stratification and development of the new therapeutic drugs in the treatment of patients with vulnerable atherosclerotic plaques.

A Transcriptional Regulation Bioinformatics Pipeline to Predict Co‐Regulated Genes in Vascular Smooth Muscle Cell Phenotypic Transitions During Atherosclerosis

The rupture of vulnerable or advanced atherosclerotic lesions contributes to myocardial infarctions and strokes, the leading causes of death globally. During all stages of atherosclerosis, vascular smooth muscle cells (VSMCs) are recruited as a major source of plaque cells within lesions, where they undergo phenotypic modulation and give rise to both plaque‐stabilizing and destabilizing phenotypes. Because most atherosclerosis studies test the functional role of single transcription factors, genes, and proteins in VSMCs, many aspects of how VSMC plasticity can be clinically exploited to prevent the rupture of vulnerable atherosclerotic lesions remain unclear. Systems biology approaches have emerged as a promising avenue for characterizing cellular dynamics at the organismal level, but they remain under‐utilized in the field of cardiovascular medicine. This study proposes a novel systems biology pipeline that integrates experimental and computational tools with large datasets measuring the transcriptomes and epigenomes of phenotypically transitioning VSMCs. Our pipeline allows users to identify candidate transcription factors that co‐regulate mouse or human gene sets controlling specific VSMC phenotypic transitions during atherosclerosis. The computational algorithms developed in this workflow integrate an array of publicly available databases, such as the Ensembl genome database and the JASPAR transcription factor database. To demonstrate the translational potential of our pipeline, we used it to test the hypothesis that the murine mesenchymal marker stem cell antigen‐1 Sca1(Ly6a) has a human ortholog, which has not been previously validated as a target in clinical therapies. To test the hypothesis that there are sets of genes co‐regulated with Ly6ain human VSMCs which, when expressed in concert, promote a distinct phenotypic state marked by Ly6ain mice, we integrated genomic and ATAC‐seq analyses of VSMCs to identify murine genes with human orthologs that bind Ly6a‐specific transcription factors. Specifically, we predict that the transcription factors ETS1, KLF5, GATA6, and SOX10 co‐regulate sets of human genes with Ly6a. While prior studies have associated these transcription factors with VSMC proliferation and phenotypic modulation, we specifically predict these Ly6a‐specific transcription factor co‐regulate the following human gene sets: PHACTR1, EFHC1, LAMC2(ETS1); TTC33, RUNX1, KIAA1217(KLF5); TMEM50A(GATA6); and ZBTB20, MYLK2(SOX10). To validate these predictions, we will determine if these transcription factors and their co‐regulated genes are expressed in single cell RNA‐sequencing analyses of human carotid arteries and can be detected with immunofluorescence staining of human coronary artery sections. We will also use siRNA to target these candidate transcription factors and genes in cultured VSMCs. The results of our pipeline will help identify novel transcriptional regulatory networks in VSMCs that can be therapeutically targeted for the treatment of advanced atherosclerosis.

Immuno-PET Imaging of Atherosclerotic Plaques with [89Zr]Zr-Anti-CD40 mAb-Proof of Concept.

Simple SummaryAtherosclerosis is characterized by gradual plaque build-up in the middle and large arteries and is the major cause of cardiovascular disease. Determining which plaques are prone to rupture and cause potential lethal effects (e.g., myocardial infarction) could greatly reduce the potential bad outcomes. CD40 is a co-stimulatory molecule present in various cells in the plaque and has been shown to correlate with plaque vulnerability. In this manuscript, we have combined a murine monoclonal antibody against CD40 (a costimulatory molecule directly linked to plaque progression and present on many cells within the lesion) with Zirconium-89 to test its applicability to detect lesions in a mouse model of atherosclerosis using PET/CT. We show that this Zirconium-89 labeled antibody can detect CD40 in atherosclerotic lesions in a mouse model of atherosclerosis. In wild type mice without plaques, no signal was found. Our results suggest that CD40 could be a potential marker for PET imaging of plaque inflammation and vulnerability.Non-invasive imaging of atherosclerosis can help in the identification of vulnerable plaque lesions. CD40 is a co-stimulatory molecule present on various immune and non-immune cells in the plaques and is linked to inflammation and plaque instability. We hypothesize that a 89Zr-labeled anti-CD40 monoclonal antibody (mAb) tracer has the potential to bind to cells present in atherosclerotic lesions and that CD40 Positron Emission Tomography (PET) can contribute to the detection of vulnerable atherosclerotic plaque lesions. To study this, wild-type (WT) and ApoE−/− mice were fed a high cholesterol diet for 14 weeks to develop atherosclerosis. Mice were injected with [89Zr]Zr-anti-CD40 mAb and the aortic uptake was evaluated and quantified using PET/Computed Tomography (CT) imaging. Ex vivo biodistribution was performed post-PET imaging and the uptake in the aorta was assessed with autoradiography and compared with Oil red O staining to determine the tracer potential to detect atherosclerotic plaques. On day 3 and 7 post injection, analysis of [89Zr]Zr-anti-CD40 mAb PET/CT scans showed a more pronounced aortic signal in ApoE−/− compared to WT mice with an increased aorta-to-blood uptake ratio. Autoradiography revealed [89Zr]Zr-anti-CD40 mAb uptake in atherosclerotic plaque areas in ApoE−/− mice, while no signal was found in WT mice. Clear overlap was observed between plaque areas as identified by Oil red O staining and autoradiography signal of [89Zr]Zr-anti-CD40 mAb in ApoE−/− mice. In this proof of concept study, we showed that PET/CT with [89Zr]Zr-anti-CD40 mAb can detect atherosclerotic plaques. As CD40 is associated with plaque vulnerability, [89Zr]Zr-anti-CD40 mAb has the potential to become a tracer to detect vulnerable atherosclerotic plaques.

MiR-223-3p inhibits the progression of atherosclerosis via down-regulating the activation of MEK1/ERK1/2 in macrophages.

Background: microRNAs (miRNAs) have drawn more attention to the progression of atherosclerosis (AS), due to their noticeable inflammation function in cardiovascular disease. Macrophages play a crucial role in disrupting atherosclerotic plaque, thereby we explored the involvement of miR-223-3p in the inflammatory response in macrophages.Methods: RT-qPCR was used to analyze the miR-223-3p levels in carotid arteries and serum of AS patients. ROC curve was used to assess the diagnostic value of miR-223-3p. Movat staining was applied to evaluate the morphological differences. FISH was used to identify the expression of miR-223-3p in macrophages of atherosclerotic lesions. Bioinformatic analysis was performed. Double-immunofluorescence and western blot were performed to assess the inflammatory cytokine secretion and p-ERK1/2. C16-PAF was injected into the culture medium of the miR-223-3p mimic/NC-transfected macrophages with ox-LDL.Results: MiR-223-3p was up-regulated in AS patients and was associated with a higher overall survival rate. MiR-223-3p was co-localized with CD68+ macrophages in vulnerable atherosclerotic lesions. MiR-223-3p mimics decreased atherosclerotic lesions, macrophages numbers whereas increased SMCs numbers in the lesions. The TNF-a immune-positive areas were reduced by miR-223-3p mimics. MAP2K1 was negatively associated with miR-223-3p. MiR-223-3p mimics reduced the inflammation and the MEK1/ERK1/2 signaling pathway in vivo and in vitro. C16-PAF reversed the effects of miR-223-3p mimics on inflammation and ERK1/2 signaling pathway.Conclusions: MiR-223-3p negatively regulates inflammatory responses by the MEK1/ERK1/2 signaling pathway. Our study provides new insight into how miR-223-3p protects against atherosclerosis, representing a broader therapeutic prospect for treating atherosclerosis by miR-223-3p.

Identification of pathology-confirmed vulnerable atherosclerotic lesions by coronary computed tomography angiography using radiomics analysis.

To explore whether radiomics-based machine learning (ML) models could outperform conventional diagnostic methods at identifying vulnerable lesions on coronary computed tomographic angiography (CCTA). In this retrospective study, 36 heart transplant recipients with coronary heart disease (CAD) and end-stage heart failure were included. Pathological cross-section samples of 350 plaques were collected and coregistered to patients' preoperative CCTA images. A total of 1184 radiomic features were extracted from CCTA images. Through feature selection and stratified fivefold cross-validation, we derived eight radiomics-based ML models for lesion vulnerability prediction. An independent set of 196 plaques from another 8 CAD patients who underwent heart transplants was collected to validate radiomics-based ML models' diagnostic accuracy against conventional CCTA feature-based diagnosis (presence of at least 2 high-risk plaque features). The performance of the prediction models was assessed by the area under the receiver operating characteristic curve (AUC) with 95% confidence intervals (CI). The training group used to develop radiomics-based ML models contained 200/350 (57.1%) vulnerable plaques and the external validation group was composed of 67.3% (132/196) vulnerable plaques. The radiomics-based ML model based on eight radiomic features showed excellent cross-validation diagnostic accuracy (AUC: 0.900 ± 0.033). In the validation group, diagnosis based on conventional CCTA features demonstrated moderate performance (AUC: 0.656 [95% CI: 0.593 -0.718]), while the radiomics-based ML model showed higher diagnostic ability (0.782 [95% CI: 0.710 -0.846]). Radiomics-based ML models showed better diagnostic ability than the conventional CCTA features at assessing coronary plaque vulnerability. • CCTA has great potential in the diagnosis of vulnerable coronary artery lesions. • Radiomics model built through CCTA could discriminate coronary vulnerable lesions in good diagnostic ability. • Radiomics model could improve the ability of vulnerability diagnosis against traditional CCTA method, sensitivity especially.

Abstract MP18: Mitochondrial Inducing Factor 1 Affects Stabilization Of Advanced Atherosclerotic Lesions In Carotid Artery Disease

Whereas cerebrovascular diseases, most and foremost ischemic events, being the second most deadliest disease as of today in the western world the process behind carotid artery plaque (CAP) vulnerability remains understood insufficiently. Through proteomic analysis of blood serum from patients treated for atherosclerotic lesions in carotid arteries we were able to determine proteins of potential relevance to CAP stability. One of the identified targets is mitochondrial apoptosis inducing factor 1 (AIFM1), which we found upregulated in serum profiles from patients with vulnerable atherosclerotic lesions. The study were conducted with human vascular tissue and blood samples from the 'Munich Vascular Biobank'. Proteomic profiling of serum was performed using the platform OLink (Uppsala, Sweden) taken from patients with either stable (n=53) or unstable (n=53) CAPs. Furthermore, gene expression of AIFM1 in stable (n=5) and unstable (n=3) CAPs was assessed via RT-qPCR .Via Immunostaining the regions showing higher expression of AIFM1 within the plaques (n=10) were determined and put in perspective with markers of cell types predominantly accumulated in those regions. In addition, blood monocyte-derived macrophages were stimulated with different factors and changes in expression of AIFM1 was assessed. With the proteomic sequencing of blood sera, higher levels of AIFM1 in patients with unstable versus stable CAP were determined. This trend was also seen assessing the gene expression of AIFM1 in the human vascular tissue. A significant enrichment of staining of AIFM1 positivity was observed in regions where apoptosis occured, such as the necrotic core and the shoulder regions of the advanced CAP. Furhtermore, AIFM1 enriched regions were identified as areas infiltrated by immune cells, especially macrophages. Monocytes of healthy donours showed an increased expression of AIFM1 when developed into macrophages. In conclusion AIFM1 was identified as a potential novel marker for advanced, unstable lesions in CAPs. Future studies (in vitro and in vivo) will reveal which role AIFM1 might play during processes that trigger CAP destabilization. Of further importance will be cell type expression patterns that we are also assessing in currently ongoing studies.

DNA methylome profiling reveals epigenetic regulation of lipoprotein-associated phospholipase A2 in human vulnerable atherosclerotic plaque

BackgroundAtherosclerotic plaque vulnerability is a key feature of atheroprogression and precipitating acute cardiovascular events. Although the pivotal role of epigenetic regulation in atherosclerotic plaque destabilization is being recognized, the DNA methylation profile and its potential role in driving the progression and destabilization of atherosclerotic cardiovascular disease remains largely unknown. We conducted a genome-wide analysis to identify differentially methylated genes in vulnerable and non-vulnerable atherosclerotic lesions to understand more about pathogenesis.ResultsWe compared genome-wide DNA methylation profiling between carotid artery plaques of patients with clinically symptomatic (recent stroke or transient ischemic attack) and asymptomatic disease (no recent stroke) using Infinium Methylation BeadChip arrays, which revealed 90,368 differentially methylated sites (FDR < 0.05, |delta beta|> 0.03) corresponding to 14,657 annotated genes. Among these genomic sites, 30% were located at the promoter regions and 14% in the CpG islands, according to genomic loci and genomic proximity to the CpG islands, respectively. Moreover, 67% displayed hypomethylation in symptomatic plaques, and the differentially hypomethylated genes were found to be involved in various aspects of inflammation. Subsequently, we focus on CpG islands and revealed 14,596 differentially methylated sites (|delta beta|> 0.1) located at the promoter regions of 7048 genes. Integrated analysis of methylation and gene expression profiles identified that 107 genes were hypomethylated in symptomatic plaques and showed elevated expression levels in both advanced plaques and ruptured plaques. The imprinted gene PLA2G7, which encodes lipoprotein-associated phospholipase A2 (Lp-PLA2), was one of the top hypomethylated genes with an increased expression upon inflammation. Further, the hypomethylated CpG site at the promoter region of PLA2G7 was identified as cg11874627, demethylation of which led to increased binding of Sp3 and expression of Lp-PLA2 through bisulfate sequencing, chromatin immunoprecipitation assay and enzyme-linked immunosorbent assay. These effects were further enhanced by deacetylase.ConclusionExtensive DNA methylation modifications serve as a new and critical layer of biological regulation that contributes to atheroprogression and destabilization via inflammatory processes. Revelation of this hitherto unknown epigenetic regulatory mechanism could rejuvenate the prospects of Lp-PLA2 as a therapeutic target to stabilize the atherosclerotic plaque and reduce clinical sequelae.

DNA Methylome Profiling Reveals Epigenetic Regulation of Lipoprotein-Associated Phospholipase A &lt;sub&gt;2&lt;/sub&gt; in Human Vulnerable Atherosclerotic Plaque

Background: Atherosclerotic plaque vulnerability is a key feature of atheroprogression and precipitating acute cardiovascular events. The DNA methylation profile and its potential role in driving the progression and destabilization of atherosclerotic cardiovascular disease remains largely unknown. We conducted a genome-wide analysis to identify differentially methylated genes in vulnerable and non-vulnerable atherosclerotic lesions to understand more about pathogenesis. Methods: Carotid artery plaques were obtained from patients with clinically symptomatic disease (recent stroke or transient ischemic attack) and asymptomatic disease. Genome-wide DNA methylation was profiled using Infinium Methylation BeadChip arrays. Gene ontology analysis was performed to reveal pathophysiological functions of differentially methylated genes. The hypomethylated genes with increased expression in atherosclerotic plaques were identified by an integrated analysis of DNA methylome with transcriptomic data. The methylation status of the CpG sites at the promoter of the top hypomethylated genes was delineated by bisulfite sequencing. Findings: Genome-wide DNA methylation profiling of symptomatic and asymptomatic plaques identified 90,368 differentially methylated sites ( p <0.05) corresponding to 14,657 annotated genes. Among these genomic sites, 30% located at promoter regions and 14% located in CpG islands, according to genomic loci and genomic proximity to the CpG islands, respectively. Moreover, 67% displayed hypomethylation in symptomatic plaques, and the differentially hypomethylated genes were found to be involved in various aspects of inflammation. The imprinted gene PLA2G7, which encodes the lipoprotein-associated phospholipase A2 (Lp-PLA2), was one of the top hypomethylated genes with an increased expression upon inflammation. Further, the hypomethylated CpG site at the promoter region of PLA2G7 was identified as cg11874627, demethylation of which increased binding of Sp3 and expression of Lp-PLA2. Interpretation: Extensive DNA methylation modifications serve as a new and critical layer of biological regulation that contributes to atheroprogression and destabilization via inflammatory processes. Revelation of this hitherto unknown epigenetic regulatory mechanism could rejuvenate the prospects of Lp-PLA2 as a therapeutic target to stabilize the atherosclerotic plaque and reduce clinical sequelae. Funding: National Natural Science Foundation of China (81770359, 81270276, and 81500365); Beijing Health Technologies Promotion Program (BHTPP202004); Open Project Fund of State Key Laboratory of Molecular Developmental Biology of China (2021-MDB-KF-18 and 2020-MDB-KF-17); and Beijing Natural Science Foundation (7172040). Declaration of Interest: The authors declare no conflict of interest relevant to the present manuscript. Ethical Approval: All procedures involving humans were approved by the Institutional Ethics Review Board of China-Japan Friendship Hospital (No. 2019-85-K56) and conformed to the standards of the Declaration of Helsinki. All participants provided written informed consent before enrollment in this study.

ERK1/2 inhibition reduces vascular calcification by activating miR-126-3p-DKK1/LRP6 pathway.

Rationale: Vascular microcalcification increases the risk of rupture of vulnerable atherosclerotic lesions. Inhibition of ERK1/2 reduces atherosclerosis in animal models while its role in vascular calcification and the underlying mechanisms remains incompletely understood.Methods: Levels of activated ERK1/2, DKK1, LRP6 and BMP2 in human calcific aortic valves were determined. ApoE deficient mice received ERK1/2 inhibitor (U0126) treatment, followed by determination of atherosclerosis, calcification and miR-126-3p production. C57BL/6J mice were used to determine the effect of U0126 on Vitamin D3 (VD3)-induced medial arterial calcification. HUVECs, HAECs and HASMCs were used to determine the effects of ERK1/2 inhibitor or siRNA on SMC calcification and the involved mechanisms.Results: We observed the calcification in human aortic valves was positively correlated to ERK1/2 activity. At cellular and animal levels, U0126 reduced intimal calcification in atherosclerotic lesions of high-fat diet-fed apoE deficient mice, medial arterial calcification in VD3-treated C57BL/6J mice, and calcification in cultured SMCs and arterial rings. The reduction of calcification was attributed to ERK1/2 inhibition-reduced expression of ALP, BMP2 and RUNX2 by activating DKK1 and LRP6 expression, and consequently inactivating both canonical and non-canonical Wnt signaling pathways in SMCs. Furthermore, we determined ERK1/2 inhibition activated miR-126-3p production by facilitating its maturation through activation of AMPKα-mediated p53 phosphorylation, and the activated miR-126-3p from ECs and SMCs played a key role in anti-vascular calcification actions of ERK1/2 inhibition.Conclusions: Our study demonstrates that activation of miR-126-3p production in ECs/SMCs and interactions between ECs and SMCs play an important role in reduction of vascular calcification by ERK1/2 inhibition.

Targeting vulnerable atherosclerotic plaque via PET-tracers aiming at cell-surface overexpression of somatostatin receptors.

Cardiovascular disease (CD) is the leading cause of death in the developed world, with major atherothrombotic events, being mainly attributed to the rupture of unstable, vulnerable atherosclerotic lesions, leading to blood flow obstruction. Since unstable atherosclerotic plaques frequently do not cause hemodynamically significant blood flow restriction, conventional stress imaging tests cannot depict the vulnerable, high-risk for rupture atherosclerotic lesions. Therefore, molecular imaging techniques targeting specific pathophysiologic features related to atherosclerotic plaque rupture mechanism, hold promise for precise and individualized treatment strategies of CD. In the current report, we describe in a patient diagnosed with pancreatic neuroendocrine tumor, the selective uptake of 68Ga-DOATATE by an atherosclerotic lesion in the thoracic aorta. This data indicates that 68Ga-DOTATATE, which is a positron emitting tomography tracer, targeting the recruitment of macrophages taking place in the vulnerable plaque, could potentially serve as an imaging probe for the detection of high-risk, prone to rupture plaques.

Protocatechuic Acid Inhibits Vulnerable Atherosclerotic Lesion Progression in Older Apoe-/- Mice

Normalization of arterial inflammation inhibits atherosclerosis. The preventive role for protocatechuic acid (PCA) in early-stage atherosclerosis is well recognized; however, its therapeutic role in late-stage atherosclerosis remains unexplored. We investigated whether PCA inhibits vulnerable atherosclerosis progression by normalizing arterial inflammation. Thirty-wk-old male apolipoprotein E-deficient (Apoe-/-) mice with vulnerable atherosclerotic lesions in the brachiocephalic artery were fed the AIN-93G diet alone (control) or supplemented with 0.003% PCA (wt:wt) for 20 wk. Lesion size and composition, IL-1β, and NF-κB in the brachiocephalic arteries, and serum lipid profiles, oxidative status, and proinflammatory cytokines (e.g., IL-1β, monocyte chemoattractant protein-1, and serum amyloid A) were measured. Moreover, the effect of PCA on the inflammation response was evaluated in efferocytic macrophages from C57BL/6J mice. Compared with the control treatment, dietary PCA supplementation significantly reduced lesion size (27.5%; P<0.05) and also improved lesion stability (P<0.05) as evidenced by increased thin fibrous cap thickness (31.7%) and collagen accumulation (58.3%), reduced necrotic core size (37.6%) and cellular apoptosis (73.9%), reduced macrophage accumulation (45.1%), and increased vascular smooth muscle cell accumulation (51.5%). Moreover, PCA supplementation inhibited IL-1β expression (53.7%) and NF-κB activation (64.4%) in lesions. However, PCA supplementation did not change serum lipid profiles, total antioxidant capacity, and inflammatory cytokines. In efferocytic macrophages, PCA at 0.5 and 1 μmol/L inhibited Il1b/IL-1β mRNA (27.2-46.5%) and protein (29.2-49.6%) expression and NF-κB activation (67.0-80.3%) by upregulation of MER proto-oncogene tyrosine kinase (MERTK) and inhibition of mitogen-activated protein kinase 3/1 (MAPK3/1). Strikingly, the similar pattern of the MERTK and MAPK3/1 changes in lesional macrophages of mice after PCA intervention in vivo was recapitulated. PCA inhibits vulnerable lesion progression in mice, which might partially be caused by normalization of arterial inflammation by upregulation of MERTK and inhibition of MAPK3/1 in lesional macrophages.

Myriocin and d-PDMP ameliorate atherosclerosis in ApoE-/- mice via reducing lipid uptake and vascular inflammation.

Sphingolipids have been implicated in the etiology of atherosclerosis. The commonly used sphingolipid inhibitors, myriocin (a ceramide inhibitor) and d-PDMP (d-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, a glycosphingolipid inhibitor), have shown therapeutic potential but their efficacy and their underlying mechanisms remain unclear. Here, apolipoprotein E-deficient (apoE-/-) mice were fed a high-fat diet (HFD) and treated with a control, myriocin, d-PDMP, or atorvastatin for 12 weeks. We analyzed the effects of these drugs on the size and detailed composition of atherosclerotic plaques. Molecular biological approaches were used to explore how the inhibitors affect lipid metabolism and foam-cell formation. Treatment with myriocin or d-PDMP led to smaller and less vulnerable atherosclerotic lesions and was almost as effective as atorvastatin. Sphingolipid inhibitors down-regulated the expression of monocyte chemotactic protein 1 (MCP-1) and its receptor chemoattractant cytokine receptor 2 (CCR2), which play a key role in monocyte recruitment. They also decreased pro-inflammatory Ly-6chigh monocytes and influenced the uptake of modified LDL by down-regulating the expression of cluster of differentiation 36 (CD36) and lectin-like oxidized LDL (ox-LDL) receptor-1 (LOX-1). The inhibitors exhibited the advantage of maintaining normal glucose homeostasis compared with atorvastatin. These findings reveal for the first time that the modulation of sphingolipid synthesis can effectively alleviate atherosclerosis progression by preventing lipid uptake and reducing inflammatory responses in the arterial walls.

Local Delivery of miR-21 Stabilizes Fibrous Caps in Vulnerable Atherosclerotic Lesions.

miRNAs are potential regulators of carotid artery stenosis andconcordant vulnerable atherosclerotic plaques. Hence, we analyzed miRNA expression in laser captured micro-dissected fibrous caps of either ruptured or stable plaques (n= 10 each), discovering that miR-21 was significantly downregulated in unstable lesions. To functionally evaluate miR-21 in plaque vulnerability, miR-21 and miR-21/apolipoprotein-E double-deficient mice (Apoe-/-miR-21-/-) were assessed. miR-21-/- mice lacked sufficient smooth muscle cell proliferation inresponse to carotid ligation injury. When exposing Apoe-/-miR-21-/- mice to an inducible plaque rupture model,they presented with more atherothrombotic events (93%) compared with miR-21+/+Apoe-/- mice (57%). We discovered that smooth muscle cell fate in experimentally induced advanced lesions is steered via a REST-miR-21-REST feedback signaling pathway. Furthermore, Apoe-/-miR-21-/- mice presented with more pronounced atherosclerotic lesions, greater foam cell formation, and substantially higher levels of arterial macrophage infiltration. Local delivery of a miR-21 mimic using ultrasound-targeted microbubbles into carotid plaques rescued the vulnerable plaque rupture phenotype. Inthe present study, we identify miR-21 as a key modulator of pathologic processes in advanced atherosclerosis. Targeted, lesion site-specific overexpression of miR-21 can stabilize vulnerable plaques.

Dual targeting improves capture of ultrasound microbubbles towards activated platelets but yields no additional benefit for imaging of arterial thrombosis

Platelets can be found on the surface of inflamed and ruptured atherosclerotic plaques. Thus, targeting of activated platelets may allow for molecular imaging of vulnerable atherosclerotic lesions. We here investigated microbubbles (MB) functionalized with the selectin ligand sialyl Lewisa individually (MBsLea) or dually with sLea and an antibody targeting ligand-induced binding sites of the activated GPIIb/IIIa receptor (MBDual). Assessed by in vitro flow chamber, targeted MB exhibited increased adhesion to platelets as compared to MBControl. While MBsLea rolled slowly on the platelets’ surface, MBDual enhanced the percentage of firm adhesion. In vivo, MB were investigated by ultrasound in a model of ferric chloride induced non-occlusive carotid artery thrombosis. MBsLea and MBDual revealed a higher ultrasound mean acoustic intensity than MBControl (p < 0.05), however MBDual demonstrated no additional increase in mean signal intensity as compared to MBsLea. The degree of carotid artery stenosis on histology correlated well with the ultrasound acoustic intensity of targeted MB (p < 0.05). While dual targeting of MB using fast binding carbohydrate polymers and specific antibodies is a promising strategy to support adhesion to activated platelets under arterial shear stress, these advantages seem not readily translatable to in vivo models.

Ficolin-2 circulating levels and intraplaque presence are associated with vulnerable atherosclerotic lesions

Plasmacytoid dendritic cells (pDCs) promote tolerance in solid organ transplants and hematopoietic stem cell transplantation (HSCT). pDCs originate from CD34+ hematopoietic progenitors. Following allogeneic hematopoietic stem cell transplant (allo-HSCT), pDC reconstitution in the BM and PB gradually attain levels similar to those in healthy individuals. We have investigated the recovery of pDC following allo-HSCT as a means to predict successful marrow engraftment. We retrospectively studied immune reconstitution of pDC in the BM of 48 patients following allo-HSCT for initial diagnoses of leukemia or other malignancies. Multi-parameter flow cytometry was used to detect the CD45+ CD123bright HLA-DR+ CD4low pDCs in BM aspirates at 2–14 months (median 6 months) post allo-HSCT. Percentages of pDCs were analyzed along with engraftment, acute graft-versus-host disease (aGVHD), event-free survival, relapse and death over a period of up to 39 months (median 30) following HSCT. We report that higher levels of pDCs in the BM post-HSCT are associated with successful engraftment, less severity of aGVHD, lower relapse rate, higher event-free survival and overall survival (P value < 0.05 for all). pDC levels detected at a shorter time interval 2–8 months (median 5 months) following HSCT also showed similar results. We conclude that pDC numbers are associated with HSCT engraftment and overall survival. Flow cytometry offers rapid quantification of pDCs as an early predictor of outcome following HSCT.

Shifting the Focus of Preclinical, Murine Atherosclerosis Studies From Prevention to Late-Stage Intervention.

Could improving the design of preclinical murine atherosclerosis studies help increase the success rate of cardiovascular clinical trials? In this Viewpoint, the authors advocate for a change from prevention to intervention study designs and rigorous lesion analyses that they argue will enhance the translational potential of murine atherosclerosis studies. Clinical management of patients with coronary artery disease (CAD) has made great progress by reducing risk factors like low-density lipoprotein cholesterol level, hypertension, and diabetes mellitus. However, late-stage events associated with coronary atherosclerosis including myocardial infarction still account for ≈16% of worldwide mortality and are forecasted to increase in prevalence.1 These events arise from 3 main processes: plaque rupture, plaque erosion, and shedding of calcific nodules. Plaque rupture accounts for the majority of CAD and typically occurs in vulnerable atherosclerotic lesions termed thin-capped fibroatheromas,2 characterized by thin fibrous caps (<65 µm) with high numbers of CD68+ macrophages relative to Acta2+ smooth muscle cells (SMC), large lipid-rich necrotic cores, and often evidence of intraplaque hemorrhage. Much of the difficulty in therapeutically targeting atherosclerosis can be attributed to (1) the nearly ubiquitous prevalence of atherosclerosis development; (2) the slow, clinically-silent progression but acute and often catastrophic presentation of symptoms; and (3) most importantly, the difficulty in identifying patients at high risk for plaque rupture or erosion and subsequent cardiovascular events. Therefore, clinical trials seeking to investigate novel CAD therapies are forced to enroll thousands of patients who already have manifestations of advanced CAD and spend hundreds of millions of dollars to conduct adequately powered phase III clinical trials to rigorously test therapeutic efficacy. And yet, cardiovascular disease trials have one of the lowest success rates of the major medical fields.3 Perhaps, the lack of success can, in part, be attributed to suboptimal design of preclinical studies, which commonly …

MRI/optical dual-modality imaging of vulnerable atherosclerotic plaque with an osteopontin-targeted probe based on Fe3O4 nanoparticles.

Rupture of vulnerable atherosclerotic plaque is the major pathological cause of luminal thrombosis in acute coronary syndromes. Since foamy macrophages have been identified as a prominent component in vulnerable atherosclerotic lesions and osteopontin (OPN) is reported to be highly expressed in foamy macrophages, OPN could be a potential target for vulnerable atherosclerotic plaque imaging. The current study designed an OPN-specific MRI/optical dual-modality probe to detect vulnerable plaques. Fluorescence imaging revealed that 24h after injection of the Cy5.5-OPN-DMSA-MNPs (COD-MNPs), the atherosclerotic plaques in carotid artery exhibited significant higher signals in high fat diet (HFD) fed mice in comparison to the group injected with Cy5.5-IgG-DMSA-MNPs (CID-MNPs) or normal diet fed group injected with COD-MNPs (1.87±0.19×1010 vs. 0.74±0.04×1010, 0.73±0.03×1010 p/sec/cm2/sr, P<0.05). Meanwhile, MRI displayed stronger T2 contrast enhancement 24h post-injection at the area of atherosclerotic plaques in the carotid of HFD fed group injected with COD-MNPs than group injected with CID-MNPs or normal diet fed group injected with COD-MNPs (post/pre signal ratio: 0.64±0.04 vs. 0.95±0.02, 0.98±0.01, P<0.05). As a dual-modality molecular probe, the resulting COD-MNPs conjugates exhibit promising potentials for noninvasive detection of vulnerable atherosclerotic plaque invivo.

Atherosclerotic Plaque Rupture

The idiom “the straw that breaks the camel’s back” describes scenarios where seemingly minor incidents eventuate in a sudden, unexpected, and often detrimental downfall. In the case of atherosclerosis, over time multiple subclinical cellular events result in the development of unstable, vulnerable atherosclerotic lesions, which leads to the rupture of atherosclerotic plaques, culminating in the often catastrophic clinical manifestation of myocardial infarction or ischemic stroke. In this review, we first summarize lessons learned from autopsy studies, clinical investigations, and animal models mainly published in ATVB . We then present recent experimental studies published in ATVB that shed light on the underlying pathophysiological development of plaque instability and disruption, and how differential and sometimes maladaptive responses at cellular levels contribute to this complex process. These many publications in ATVB are a testament to the journal’s leading role in research on atherosclerotic plaque instability, an area of research with utmost translational relevance. Our understanding of the pathology of unstable, vulnerable atherosclerotic plaques is mainly based on a limited number of postmortem examinations of human coronary arteries and the analysis of resected surgical specimens from patients who underwent carotid endarterectomy and performed for primary/secondary prevention of transient ischemia attack or stroke.1–3 The histopathologic definition of unstable plaques includes, as the most central features, thin fibrous caps (thickness 40% of the total lesion volume).4–7 Importantly, repeated subclinical plaque ruptures, histologically and potentially macroscopically visible as intraplaque hemorrhage, are described as an additional cause of plaque instability.8 From an autopsy series of 800 cases of sudden coronary …