A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association

Atherosclerosis is a side effect of cellular senescence

Atherosclerosis is a systemic autoimmune disease of the arterial wall characterized by chronic inflammation, high blood pressure, oxidative stress, and progressive loss of cell and organ function with aging. An imbalance of macrophage polarization is associated with many aging diseases, including atherosclerosis. The polarization toward the pro-inflammatory M1 macrophage is a major promoter of the atheroma formation. It is known that efferocytosis, or ingestion of apoptotic cells, is stimulated by M2 macrophage polarization. A failure of efferocytosis leads to the prolongation of chronic pathology in tissue. In addition, fat-laden macrophages contribute to the plague progression by transforming into foam cells in response to excess lipid deposition in arteries. In spite of the generally accepted theory that macrophages capture oxidized low-density lipoprotein by phagocytosis and become foam cells, we postulate that the main source of lipid accumulation in foam cells are senescent erythrocytes. Senescent erythrocytes lose their plasticity, which affects the rheological blood properties. It is known that their membrane contains high levels of cholesterol. There is evidence that senescent erythrocytes play a pathogenic role in the atheroma formation after breaking down during flowing through an artery bifurcation. Here we review the current knowledge on the impact of age-associated immune cells and red blood cells modifications on atherogenesis.

Graphical abstract:

Clock Gene Bmal1 Disruption in Vascular Smooth Muscle Cells Worsens Carotid Atherosclerotic Lesions

BACKGROUND

Clock system disruptions are associated with cardiovascular diseases. We previously demonstrated Bmal1 (brain muscle aryl nuclear translocase like-1) expression is significantly attenuated in plaque-derived vascular smooth muscle cells (VSMCs). However, the influence of Bmal1 disruption in VSMCs and its molecular targets are still unclear. Here, we aim to define how Bmal1 disruption in VSMCs influences the atherosclerosis lesions.

METHODS

The relationship among Bmal1, neurological symptoms, and plaque stability was investigated. VSMC Bmal1^-/- and VSMC Bmal1^+/+mice were generated and injected with adeno associated virus encoding mutant proprotein convertase subtilisin/kexin type 9 to induce atherosclerosis. Carotid artery ligation and cuff placement were performed in these mice to confirm the role of Bmal1 in atherosclerosis progression. The relevant molecular mechanisms were then explored.

RESULTS

Bmal1 expression in the carotid plague was significantly lower in symptomatic patients as well as in unstable plaques. Moreover, Bmal1 reduction is an independent risk factor for neurological symptoms and plaque instability. Besides, VSMC Bmal1^-/- mice exhibit aggravated atherosclerotic lesions. Further study demonstrated that Bmal1 downregulation in VSMCs increased VSMC migration, monocyte transmigration, reactive oxygen species levels, and VSMCs apoptosis. As for the mechanism, we revealed that Bmal1 suppresses VSMCs migration by inhibiting RAC1 activity in 2 ways: by activating the transcription of RhoGDIα and by interacting with RAC1. Besides, Bmal1 was shown to preserve antioxidant function in VSMCs by activating Nrf2 (nuclear factor erythroid 2-related factor 2) and Bcl-2 transcription.

CONCLUSIONS

Bmal1 disruption in VSMCs worsens atherosclerosis by promoting VSMC migration and monocyte transmigration and impairing antioxidant function. Therefore, Bmal1 may be a potential therapeutic target and biomarker of atherosclerosis in the future.

Endothelial Intracellular ANG (Angiogenin) Protects Against Atherosclerosis by Decreasing Endoplasmic Reticulum Stress

BACKGROUND

ANG (angiogenin) is essential for cellular adaptation to endoplasmic reticulum (ER) stress, a process closely associated with cardiovascular diseases, including atherosclerosis. We aimed to investigate the role of ANG in the progression of atherosclerosis and elucidate its underlying molecular mechanisms.

METHODS

We constructed adenoassociated virus 9 ANG overexpression vectors and endothelial ANG- and ApoE (apolipoprotein E)-deficient mice to determine the effects of ANG on ER stress and atherosclerotic lesions. RNA sequencing of endothelial ANG- and ApoE-deficient mice identified ANG-dependent downregulation of ST3GAL5 (ST3 beta-galactoside alpha-2,3-sialyltransferase 5) expression, and the direct regulation of ST3GAL5 by ANG was verified by chromatin immunoprecipitation sequencing and luciferase reporter assay results.

RESULTS

Reanalysis of expression profiling datasets indicated decreased ANG levels in patients' atherosclerotic lesions, and these data were validated in aortas from ApoE^-/- mice. ER stress marker and adhesion molecule levels, aortic root lesions and macrophage deposition were substantially reduced in ApoE^-/- mice injected with an adenoassociated virus 9 ANG without signal peptide (ANG-ΔSP) overexpression vector compared with empty and full-length ANG overexpression vectors. Endothelial ANG deficiency significantly elevated ER stress and increased adhesion molecule expression, which aggravated atherosclerotic lesions and enhanced THP-1 monocyte adhesion to endothelial cells in vivo and in vitro, respectively. Furthermore, ANG-ΔSP overexpression significantly attenuated oxidized low-density lipoprotein-induced ER stress and THP-1 monocyte adhesion to endothelial cells, which were reversed by ST3GAL5 inhibition.

CONCLUSIONS

These results suggest that endothelial intracellular ANG is a novel therapeutic against atherosclerosis and exerts atheroprotective effects via ST3GAL5-mediated ER stress suppression.

A histological study of atherosclerotic characteristics in age-related macular degeneration

This study investigated the pathogenesis of age-related macular degeneration (AMD) using histological methods that are commonly used for atherosclerotic vascular disease (ASVD). 1 normal, 3 early dry AMD, and 1 late dry AMD eyes were obtained from the Lions Eye Bank of Oregon and systematically dissected. They were stained with hematoxylin and eosin, Oil red O, Masson, Elastica van Gieson, Alizarin red, and Prussian blue. Additionally, the normal and late dry AMD eyes were immunostained for a-smooth muscle actin, CD45, and CD68 with Nile red and DAPI. Correlations were found between severity of AMD and lipid accumulation in the deep sclera (+), numbers of drusen between the Bruch's membrane and retinal pigment epithelium (RPE) (+), amount of collagen in the deep sclera (+), and amount of elastin in the deep sclera (-) (P < 0.1). Geographic atrophy, RPE detachment, and abnormal capillary shape and distribution in the choriocapillaris were observed in the fovea of late AMD. There were no stenosis, plaque, hemorrhage, and calcification. Additionally, late AMD tended to have higher smooth muscle thicknesses of the choroidal vascular walls, lower numbers of T lymphocytes in the choroid, and higher numbers of macrophages near the RPE and in the choroid relative to normal (P < 0.1). Macrophages-derived foam cells were detected near the Bruch's membrane in late AMD. Therefore, the present study showed many histological characteristics of ASVD in AMD, which suggests an association between them; however, there were also some histological characteristics of ASVD that were not found in AMD, which indicates that there exist pathogenic differences between them. The results generally support the vascular model of AMD, but some details still need clarification.

Differences in Vasa Vasorum Distribution in Human Aortic Aneurysms and Atheromas

The pathophysiological difference between aortic atheromas and aneurysms is unknown. We focused on the vasa vasorum (VV), which play a critical role in maintaining aortic homeostasis and are also involved in vascular diseases. We investigated the differences in VV between the atheromas and aneurysms. Human abdominal aortic samples were obtained from patients with abdominal aortic aneurysm during surgery or autopsy cases. Autopsy cases were divided into 2 groups according to atheromas. The VV were evaluated using immunohistochemical staining for von Willebrand factor. Intimal VV increased in both the atheroma and aneurysm groups, medial VV increased, and adventitial VV decreased only in the aneurysm group. We also observed that the medial VV were connected to the adventitial VV in the atheroma group and to intimal VV in the aneurysm group. We suggest the outside-in VV or inside-out VV theories. Atheroma induces hypoxia of aortic walls, and angiogenic factors might induce an increase of intimal VV derived from adventitial VV (outside-in VV). However, adventitial VV decrease induces hypoxia of aortic walls, and angiogenic factors might induce an increase of intimal VV derived from aortic lumen (inside-out VV). These differences of VV may contribute in elucidating the pathophysiology of aortic diseases.

Carotid atherosclerotic disease: A systematic review of pathogenesis and management

Carotid stenosis is an important contributor to ischemic stroke risk with resultant significant impact on neurological disability and death in adults and with worldwide implications. Management of carotid stenosis is impacted by whether there are associated symptoms along with the degree of stenosis. Understanding of the pathogenesis of carotid atherosclerosis or stenosis is important in management of carotid stenosis. Atherosclerotic plaque formation is a chronic insidious process with a number of potential contributors to the formation of such a plaque. The definition of atherosclerosis is not simply limited to abnormal deposition of lipid but also includes a chronic, complex, inflammatory process. Molecularly, in atherosclerosis, there is decreasing nitric oxide (NO) bioavailability, activity and/or expression of endothelial NO synthase, or increasing degradation of NO secondary to enhanced superoxide production. These above changes cause endothelial dysfunction leading to formation of foam cell followed by formation on lipid plaque. After lipid plaque formation, stable or unstable atherosclerotic plaque is formed depending on the calcium deposition over the lipid plaque. It continues to be clearly established that carotid intervention for symptomatic high-grade carotid stenosis is best managed with intervention either by carotid endarterectomy or carotid stenting. However, asymptomatic carotid stenosis is the subject of considerable controversy in terms of optimal management. This review of carotid atherosclerosis is an attempt to incorporate the information provided by more recent studies on pathogenesis and management which may help in the decision-making process for optimal management for protection against stroke.

Effect of FURIN SNP rs17514846 on coronary atherosclerosis in human cardiac specimens: An autopsy study of 106 cases

BACKGROUND

Coronary artery disease (CAD), including coronary atherosclerosis (CAS), is one of the most common causes of death. The FURIN SNP rs17514846 is assumed to be a risk factor for CAD. We evaluated this relationship using autopsy specimens and autopsy data, such as the histopathological degree of CAS.

MATERIALS AND METHODS

A total of 106 samples were genotyped from obtained blood samples. Myocardial and coronary arterial FURIN levels were quantified by ELISA. The degree of CAS was classified histopathologically according to the Stary classification, and the localization of FURIN was examined by immunostaining. The obtained data were analyzed statistically.

RESULTS

FURIN expression was widely observed in the myocardium, vascular smooth muscle cells, endothelial cells, adipocytes, and macrophages. FURIN level in the myocardium of cases with the AA genotype at the FURIN SNP rs17514846 was higher than that in CC cases. Additionally, FURIN levels in both coronary arteries and myocardium were higher at the early stage of CAS than at the late stage microscopically.

CONCLUSION

Our study suggested that the A allele of rs17514846 is associated with higher FURIN level in the heart and that FURIN exhibits a higher level in the early stage of CAS. These findings deepen our understanding of the mechanism of CAS.

Ultrasound Technologies and the Diagnosis of Giant Cell Arteritis

Giant cell arteritis (GCA) is a primary autoimmune vasculitis that specifically affects medium-sized extracranial arteries, like superficial temporal arteries (TAs). The most important data to be considered for the ultrasound (US) diagnosis of temporal arteritis are stenosis, acute occlusions and “dark halo” sign, which represent the edema of the vascular wall. The vessel wall thickening of large vessels in GCA can be recognized by the US, which has high sensitivity and is facile to use. Ocular complications of GCA are common and consist especially of anterior arterial ischemic optic neuropathies or central retinal artery occlusion with sudden, painless, and sharp loss of vision in the affected eye. Color Doppler imaging of the orbital vessels (showing low-end diastolic velocities and a high resistance index) is essential to quickly differentiate the mechanism of ocular involvement (arteritic versus non-arteritic), since the characteristics of TAs on US do not correspond with ocular involvement on GCA. GCA should be cured immediately with systemic corticosteroids to avoid further visual loss of the eyes.

Multiscale Computational Modeling of Vascular Adaptation: A Systems Biology Approach Using Agent-Based Models

The widespread incidence of cardiovascular diseases and associated mortality and morbidity, along with the advent of powerful computational resources, have fostered an extensive research in computational modeling of vascular pathophysiology field and promoted in-silico models as a support for biomedical research. Given the multiscale nature of biological systems, the integration of phenomena at different spatial and temporal scales has emerged to be essential in capturing mechanobiological mechanisms underlying vascular adaptation processes. In this regard, agent-based models have demonstrated to successfully embed the systems biology principles and capture the emergent behavior of cellular systems under different pathophysiological conditions. Furthermore, through their modular structure, agent-based models are suitable to be integrated with continuum-based models within a multiscale framework that can link the molecular pathways to the cell and tissue levels. This can allow improving existing therapies and/or developing new therapeutic strategies. The present review examines the multiscale computational frameworks of vascular adaptation with an emphasis on the integration of agent-based approaches with continuum models to describe vascular pathophysiology in a systems biology perspective. The state-of-the-art highlights the current gaps and limitations in the field, thus shedding light on new areas to be explored that may become the future research focus. The inclusion of molecular intracellular pathways (e.g., genomics or proteomics) within the multiscale agent-based modeling frameworks will certainly provide a great contribution to the promising personalized medicine. Efforts will be also needed to address the challenges encountered for the verification, uncertainty quantification, calibration and validation of these multiscale frameworks.

Diet and exercise reduce pre-existing NASH and fibrosis and have additional beneficial effects on the vasculature, adipose tissue and skeletal muscle via organ-crosstalk

BACKGROUND

Non-alcoholic steatohepatitis (NASH) has become one of the most common liver diseases and is still without approved pharmacotherapy. Lifestyle interventions using exercise and diet change remain the current treatment of choice and even a small weight loss (5-7%) can already have a beneficial effect on NASH. However, the underlying molecular mechanisms of exercise and diet interventions remain largely elusive, and it is unclear whether they exert their health effects via similar or different pathways.

METHODS

Ldlr-/-.Leiden mice received a high fat diet (HFD) for 30 weeks to establish a severe state of NASH/fibrosis with simultaneous atherosclerosis development. Groups of mice were then either left untreated (control group) or were treated for 20 weeks with exercise (running wheel), diet change (switch to a low fat chow diet) or the combination thereof. The liver and distant organs including heart, white adipose tissue (WAT) and muscle were histologically examined. Comprehensive transcriptome analysis of liver, WAT and muscle revealed the organ-specific effects of exercise and diet and defined the underlying pathways.

RESULTS

Exercise and dietary change significantly reduced body weight, fat mass, adipocyte size and improved myosteatosis and muscle function with additive effects of combination treatment. WAT inflammation was significantly improved by diet change, tended to be reduced with exercise, and combination therapy had no additive effect. Hepatic steatosis and inflammation were almost fully reversed by exercise and diet change, while hepatic fibrosis tended to be improved with exercise and was significantly improved with diet change. Additive effects for the combination therapy were shown for liver steatosis and associated liver lipids, and atherosclerosis, but not for hepatic inflammation and fibrosis. Pathway analysis revealed complementary effects on metabolic pathways and lipid handling processes, thereby substantiating the added value of combined lifestyle treatment.

CONCLUSIONS

Exercise, diet change and the combination thereof can reverse established NASH/fibrosis in obese Ldlr-/-.Leiden mice. In addition, the lifestyle interventions had beneficial effects on atherosclerosis, WAT inflammation and muscle function. For steatosis and other parameters related to adiposity or lipid metabolism, exercise and dietary change affected more distinct pathways that acted complementary when the interventions were combined resulting in an additive effect for the combination therapy on important endpoints including NASH and atherosclerosis. For inflammation, exercise and diet change shared several underlying pathways resulting in a net similar effect when the interventions were combined.

The Initial Human Atherosclerotic Lesion and Lipoprotein Modification-A Deep Connection

Atherosclerosis research typically focuses on the evolution of intermediate or advanced atherosclerotic lesions rather than on prelesional stages of atherogenesis. Yet these early events may provide decisive leads on the triggers of the pathologic process, before lesions become clinically overt. Thereby, it is mandatory to consider extracellular lipoprotein deposition at this stage as the prerequisite of foam cell formation leading to a remarkable accumulation of LDL (Low Density Lipoproteins). As progression of atherosclerosis displays the characteristic features of a chronic inflammatory process on the one hand and native LDL lacks inflammatory properties on the other hand, the lipoprotein must undergo biochemical modification to become atherogenic. During the last 25 years, evidence was accumulated in support of a different concept on atherogenesis proposing that modification of native LDL occurs through the action of ubiquitous hydrolytic enzymes (enzymatically modified LDL or eLDL) rather than oxidation and contending that the physiological events leading to macrophage uptake and reverse transport of eLDL first occur without inflammation (initiation with reversion). Preventing or reversing initial atherosclerotic lesions would avoid the later stages and therefore prevent clinical manifestations. This concept is in accordance with the response to retention hypothesis directly supporting the strategy of lowering plasma levels of atherogenic lipoproteins as the most successful therapy for atherosclerosis and its sequelae. Apart from but unquestionable closely related to this concept, there are several other hypotheses on atherosclerotic lesion initiation favoring an initiating role of the immune system ('vascular-associated lymphoid tissue' (VALT)), defining foam cell formation as a variant of lysosomal storage disease, relating to the concept of the inflammasome with crystalline cholesterol and/or mitochondrial DAMPs (damage-associated molecular patterns) being mandatory in driving arterial inflammation and, last but not least, pointing to miRNAs (micro RNAs) as pivotal players. However, direct anti-inflammatory therapies may prove successful as adjuvant components but will likely never be used in the absence of strategies to lower plasma levels of atherogenic lipoproteins, the key point of the perception that atherosclerosis is not simply an inevitable result of senescence. In particular, given the importance of chemical modifications for lipoprotein atherogenicity, regulation of the enzymes involved might be a tempting target for pharmacological research.

Danlou Tablets Inhibit Atherosclerosis in Apolipoprotein E-Deficient Mice by Inducing Macrophage Autophagy: The Role of the PI3K-Akt-mTOR Pathway

Atherosclerosis (AS) is a type of chronic vascular disease, and its etiology is not yet fully understood. AS is characterized by lipid deposition, atherosclerotic plaque formation, vascular stenosis or even complete blockage of the blood vessel wall. Clinical studies have shown that Danlou tablets (DLTs) can improve the heart function, quality of life, and prognosis of patients with coronary heart disease and myocardial infarction. However, its mechanism of action remains unknown. Our study revealed that DLTs ameliorated ApoE^−/−AS mouse aortic atherosclerotic plaques [hematoxylin-eosin (HE) staining and small animal ultrasound] and reduced CD68⁺ macrophage infiltration, the expression of the inflammatory factor interferon-gamma (IFN-γ), vascular smooth muscle α-actin, and serum lipid levels. In vitro, in the macrophage foaming model, DLTs partially restored the activity of RAW264.7 cells, reduced the uptake of lipid droplets, and inhibited lipid droplet accumulation and apoptosis within BMDMs. We also found that Torin1, an autophagy agonist, reduced intracellular lipid deposition in BMDMs, as did DLTs. Moreover, DLTs upregulated the expression of the autophagy-related protein LC3II and decreased p62 accumulation in RAW264.7 cells. DLTs also inhibited the phosphorylation of p-PI3K, p-Akt, and p-mTOR, leading to upregulated autophagy in RAW264.7 cells. In summary, our results suggested that DLTs can promote autophagy in macrophages by inhibiting the PI3K/Akt/mTOR signaling pathway, thereby reducing foam cell formation and improving atherosclerosis.

Accumulation of Plasma-Derived Lipids in the Lipid Core and Necrotic Core of Human Atheroma: Imaging Mass Spectrometry and Histopathological Analyses

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Blood Cell Count Indexes of Systemic Inflammation in Carotid Artery Disease: Current Evidence and Future Perspectives

Carotid artery disease is commonly encountered in clinical practice and accounts for approximately 30% of ischemic strokes in the general population. Numerous biomarkers have been investigated as predictors of the onset and progression of carotid disease, the occurrence of cerebrovascular complications, and overall prognosis. Among them, blood cell count (BCC) indexes of systemic inflammation might be particularly useful, from a pathophysiological and clinical point of view, given the inflammatory nature of the atherosclerotic process. The aim of this review is to discuss the available evidence regarding the role of common BCC indexes, such as the neutrophil to lymphocyte ratio (NLR), monocyte to lymphocyte ratio (MLR), platelet to lymphocyte ratio (PLR), mean platelet volume (MPV), platelet distribution width (PDW), and red cell distribution width (RDW), in the diagnosis and risk stratification of carotid artery disease, and their potential clinical applications.

Roadmap Consensus on Carotid Artery Plaque Imaging and Impact on Therapy Strategies and Guidelines: An International, Multispecialty, Expert Review and Position Statement

Current guidelines for primary and secondary prevention of stroke in patients with carotid atherosclerosis are based on the quantification of the degree of stenosis and symptom status. Recent publications have demonstrated that plaque morphology and composition, independent of the degree of stenosis, are important in the risk stratification of carotid atherosclerotic disease. This finding raises the question as to whether current guidelines are adequate or if they should be updated with new evidence, including imaging for plaque phenotyping, risk stratification, and clinical decision-making in addition to the degree of stenosis. To further this discussion, this roadmap consensus article defines the limits of luminal imaging and highlights the current evidence supporting the role of plaque imaging. Furthermore, we identify gaps in current knowledge and suggest steps to generate high-quality evidence, to add relevant information to guidelines currently based on the quantification of stenosis.

Arteriosclerosis, atherosclerosis, arteriolosclerosis, and Monckeberg medial calcific sclerosis: what is the difference?

Cardiovascular diseases are the main cause of death in contemporary times. Arteriosclerosis, atherosclerosis, arteriolosclerosis, and Monckeberg's arteriosclerosis are terms that are often used interchangeably, but they refer to different vascular pathologies. The objective of this study is to review the concepts of atherosclerosis, atherosclerosis, arteriosclerosis and Monckeberg medial calcific sclerosis (MMCS). The term arteriosclerosis is more generic, meaning the stiffening and consequent loss of elasticity of the arterial wall, and encompasses the other terms. Atherosclerosis is an inflammatory disease secondary to lesions in the intimal layer and whose main complication is acute and chronic obstruction of the arterial lumen. Arteriolosclerosis refers to thickening of arterioles, particularly in association with systemic arterial hypertension. MMCS refers to non-obstructive calcification in the internal elastic lamina or the tunica media of muscular arteries. Vascular calcifications, which include atherosclerotic lesions and MMCS, have been studied as a risk factor for cardiovascular morbidity and mortality.

Coronary artery calcium progression after coronary artery bypass grafting surgery

OBJECTIVES

Accelerated atherosclerosis is a well-established phenomenon after coronary artery bypass grafting surgery (CABG). In this study, we analysed coronary artery calcium (CCS) progression after CABG.

METHODS

We retrospectively measured the CCS Agatston score (AS), volume score (VS) and mass score (MS) of 39 patients before and after CABG. The annualised CCS change and annualised CCS percent change of each coronary artery, coronary artery segments proximal and distal to anastomosis were analysed.

RESULTS

Mean age at the time of the surgery was 59.8±8.5 years. Follow-up period between the first and second CT scans was 6.7±2.8 (range, 1.1-12.8) years. Annualised CCS percent change (AS, VS and MS) of the coronary segments proximal-to-anastomosis did not differ from that of the non-grafted coronary arteries as follow: segments proximal-to-anastomosis: median (Q1-Q3) 12.8 (5.0-37.4), 13.7 (6.1-41.1) and 14.9 (5.4-53.7), left main coronary artery 12.6 (7.4-43.8), 22.0 (8.1-44.4) and 18.2 (7.3-57.4), non-grafted left circumflex artery: 13.5 (4.4-38.1), 10.5 (2.9-45.2) and 11.5 (7.1-47.9) and non-grafted right coronary artery: 31.4 (14.4-74.5), 25.2 (16.7-62.0) and 31.3 (23.8-85.6), respectively. Likewise, annualised percent change (AS, VS and MS) was similar between the native coronary arteries. Multivariate regression analysis showed that diabetes mellitus was the only predictor of annualised percent progression of the total CCS of >15% (HR, 8.12; 95% CI, 1.05 to 26.6; p=0.04).

CONCLUSION

The CCS post-CABG did not follow an accelerated progression process. Among coronary artery disease risk factors, diabetes mellitus is the only predictor of annualised CCS percent progression of >15% post-CABG.

Pharmacological inhibition of EZH2 by GSK126 decreases atherosclerosis by modulating foam cell formation and monocyte adhesion in apolipoprotein E-deficient mice

Histone modifications play an important role in the occurrence and development of atherosclerosis in human and atherosclerosis-prone mice. Histone methylation in macrophages, monocytes and endothelial cells markedly influence the progression of atherosclerosis. However, it remains unclear whether treatment with a histone methyltransferase enhancer of zeste homolog 2 (EZH2) inhibitor may suppress atherosclerosis. The present study aimed to determine the effects of the EZH2 inhibitor, GSK126, on the suppression and regression of atherosclerosis in apolipoprotein E-deficient mouse models. In vitro, it was found that pharmacological inhibition of EZH2 by GSK126 markedly reduced lipid transportation and monocyte adhesion during atherogenesis, predominantly through increasing the expression levels of ATP-binding cassette transporter A1 and suppressing vascular cell adhesion molecule 1 in human THP-1 cells. In vivo, it was found that atherosclerotic plaques in GSK126-treated mice were significantly decreased when comparing with the vehicle-treated animals. These results indicated that the GSK126 has the ability to attenuate the progression of atherosclerosis by reducing macrophage foam cell formation and monocyte adhesion in cell and mouse models. In conclusion, the present study provided new insights into the molecular mechanism behind the action of GSK126 and suggested its therapeutic potential for the treatment of atherosclerosis.

Association between carotid plaque vulnerability and high mobility group box-1 serum levels in a diabetic population

Background

Carotid atherosclerosis represents one of the complications of diabetes mellitus. In particular, plaque instability contributes to disease progression and stroke incidence. High mobility group box-1 (HMGB1) is a nuclear protein involved in promotion and progression of atherosclerosis and cardiovascular diseases. The aim of this study was to analyze the relationship between HMGB1 serum levels, main inflammatory cytokines, the presence of internal carotid stenosis and unstable plaque in a diabetic population.

Research design and methods

We studied 873 diabetic patients, including 347 patients with internal carotid artery stenosis (ICAS) who underwent carotid endarterectomy and 526 diabetic patients without internal carotid artery stenosis (WICAS). At baseline, HMGB1 and the main inflammatory cytokines serum levels were evaluated. For ICAS patients, the histological features of carotid plaque were also collected to differentiate them in patients with stable or unstable atherosclerotic lesions.

Results

We found that HMGB1 serum levels, osteoprotegerin, high-sensitivity C-reactive protein, tumor necrosis factor-alpha and interleukin-6, were significantly higher in diabetic ICAS patients compared to diabetic WICAS patients. Among ICAS patients, individuals with unstable plaque had higher levels of these cytokines, compared to patients with stable plaque. A multivariable stepwise logistic regression analysis showed that HMGB1 and osteoprotegerin remained independently associated with unstable plaque in ICAS patients.

Conclusions

The present study demonstrated that HMGB1 is an independent risk factor for carotid plaque vulnerability in an Italian population with diabetes mellitus, representing a promising biomarker of carotid plaque instability and a possible molecular target to treat unstable carotid plaques and to prevent stroke.

Optoacoustic Imaging in Inflammation

Optoacoustic or photoacoustic imaging (OAI/PAI) is a technology which enables non-invasive visualization of laser-illuminated tissue by the detection of acoustic signals. The combination of "light in" and "sound out" offers unprecedented scalability with a high penetration depth and resolution. The wide range of biomedical applications makes this technology a versatile tool for preclinical and clinical research. Particularly when imaging inflammation, the technology offers advantages over current clinical methods to diagnose, stage, and monitor physiological and pathophysiological processes. This review discusses the clinical perspective of using OAI in the context of imaging inflammation as well as in current and emerging translational applications.

Quantification of Carotid Plaque Histology Using iPlaque Software

The iPlaque software package can use integrated backscatter (IB) values of carotid plaque to extract information on tissue composition. The aim of this study was to evaluate the association between the plaque histologic classification and IB values evaluated by iPlaque. In 49 patients undergoing carotid endarterectomy, IB values of whole carotid plaque were measured using iPlaque from the long-axis ultrasonographic image. Histologic findings of resected plaques were defined using the classification of the American Heart Association. The average IB values were statistically compared with the classification. Plaque samples from 49 patients were categorized into V, VI and VII, (13, 32 and 4 cases, respectively). Both the average and standard deviation of the IB values in each plaque sample significantly differed among the three classifications (p = 0.001). The IB of carotid plaque obtained by iPlaque analysis was associated with its histologic characteristics.

Deletion of fibroblast activation protein provides atheroprotection

AIMS

Fibroblast activation protein (FAP) is upregulated at sites of tissue remodelling including chronic arthritis, solid tumours, and fibrotic hearts. It has also been associated with human coronary atherosclerotic plaques. Yet, the causal role of FAP in atherosclerosis remains unknown. To investigate the cause-effect relationship of endogenous FAP in atherogenesis, we assessed the effects of constitutive Fap deletion on plaque formation in atherosclerosis-prone apolipoprotein E (Apoe) or low-density lipoprotein receptor (Ldlr) knockout mice.

METHODS AND RESULTS

Using en face analyses of thoraco-abdominal aortae and aortic sinus cross-sections, we demonstrate that Fap deficiency decreased plaque formation in two atherosclerotic mouse models (-46% in Apoe and -34% in Ldlr knockout mice). As a surrogate of plaque vulnerability fibrous cap thickness was used; it was increased in Fap-deficient mice, whereas Sirius red staining demonstrated that total collagen content remained unchanged. Using polarized light, atherosclerotic lesions from Fap-deficient mice displayed increased FAP targets in terms of enhanced collagen birefringence in plaques and increased pre-COL3A1 expression in aortic lysates. Analyses of the Stockholm Atherosclerosis Gene Expression data revealed that FAP expression was increased in human atherosclerotic compared to non-atherosclerotic arteries.

CONCLUSIONS

Our data provide causal evidence that constitutive Fap deletion decreases progression of experimental atherosclerosis and increases features of plaque stability with decreased collagen breakdown. Thus, inhibition of FAP expression or activity may not only represent a promising therapeutic target in atherosclerosis but appears safe at the experimental level for FAP-targeted cancer therapies.

Hydrogen Sulfide and its Interaction with Other Players in Inflammation

Hydrogen sulfide (H₂S) plays a vital role in human physiology and in the pathophysiology of several diseases. In addition, a substantial role of H₂S in inflammation has emerged. This chapter will discuss the involvement of H₂S in various inflammatory diseases. Furthermore, the contribution of reactive oxygen species (ROS), adhesion molecules, and leukocyte recruitment in H₂S-mediated inflammation will be discussed. The interrelationship of H₂S with other gasotransmitters in inflammation will also be examined. There is mixed literature on the contribution of H₂S to inflammation due to studies reporting both pro- and anti-inflammatory actions. These apparent discrepancies in the literature could be resolved with further studies.

Hypolipidemic and Hepatoprotective Effects of Polysaccharides Extracted from Liriope spicata Var. Prolifera in C57BL/6J Mice with High-Fat Diet-Induced Hyperlipidemia

In this study, C57BL/6J mice with high-fat diet- (HFD-) induced hyperlipidemia were treated with total Liriope spicata var. prolifera polysaccharides (TLSP: 200, 400, and 800 mg/kg body weight), simvastatin (3 mg/kg body weight), or saline for 8 weeks, respectively. The results showed that TLSP had strong lipid-lowering and hepatoprotective effects on C57BL/6J mice with HFD-induced hyperlipidemia. TLSP administration significantly reduced serum total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) levels and downregulated the expressions of peroxisome proliferator-activated receptor (PPAR)γ and fatty acid synthase (FAS) in the adipose and liver tissues of the mice. TLSP exerted hypolipidemic and hepatoprotective effects by activating lipid/bile acid metabolism via the FXH-SHP/CYP7A1 and SEBP-1c/FAC/ACC signaling pathways. Thus, TLPS is a promising natural polymer with hepatoprotective and hypolipidemic properties.

Using optical coherence tomography and intravascular ultrasound imaging to quantify coronary plaque cap thickness and vulnerability: a pilot study

Background

Detecting coronary vulnerable plaques in vivo and assessing their vulnerability have been great challenges for clinicians and the research community. Intravascular ultrasound (IVUS) is commonly used in clinical practice for diagnosis and treatment decisions. However, due to IVUS limited resolution (about 150–200 µm), it is not sufficient to detect vulnerable plaques with a threshold cap thickness of 65 µm. Optical Coherence Tomography (OCT) has a resolution of 15–20 µm and can measure fibrous cap thickness more accurately. The aim of this study was to use OCT as the benchmark to obtain patient-specific coronary plaque cap thickness and evaluate the differences between OCT and IVUS fibrous cap quantifications. A cap index with integer values 0–4 was also introduced as a quantitative measure of plaque vulnerability to study plaque vulnerability.

Methods

Data from 10 patients (mean age: 70.4; m: 6; f: 4) with coronary heart disease who underwent IVUS, OCT, and angiography were collected at Cardiovascular Research Foundation (CRF) using approved protocol with informed consent obtained. 348 slices with lipid core and fibrous caps were selected for study. Convolutional Neural Network (CNN)-based and expert-based data segmentation were performed using established methods previously published. Cap thickness data were extracted to quantify differences between IVUS and OCT measurements.

Results

For the 348 slices analyzed, the mean value difference between OCT and IVUS cap thickness measurements was 1.83% (p = 0.031). However, mean value of point-to-point differences was 35.76%. Comparing minimum cap thickness for each plaque, the mean value of the 20 plaque IVUS-OCT differences was 44.46%, ranging from 2.36% to 91.15%. For cap index values assigned to the 348 slices, the disagreement between OCT and IVUS assignments was 25%. However, for the OCT cap index = 2 and 3 groups, the disagreement rates were 91% and 80%, respectively. Furthermore, the observation of cap index changes from baseline to follow-up indicated that IVUS results differed from OCT by 80%.

Conclusions

These preliminary results demonstrated that there were significant differences between IVUS and OCT plaque cap thickness measurements. Large-scale patient studies are needed to confirm our findings.

LncRNA HCG11 regulates proliferation and apoptosis of vascular smooth muscle cell through targeting miR-144-3p/FOXF1 axis in atherosclerosis

BACKGROUND

Atherosclerosis (AS) is the main pathological basis of coronary heart disease, cerebral infarction and peripheral vascular disease, which seriously endanger people's life and health. In recent years, long non-coding RNA (lncRNA) has been found to be involved in gene expression regulation, but the research on AS is still in the initial stage. In this study, we mainly studied the role of HCG11 in patients with AS. Quantitative Real-time Polymerase Chain Reaction (QRT-PCR) was used to detect the expression of HCG11 and miR-144 in the serum of AS patients and healthy volunteers. Oxidation Low Lipoprotein (Ox-LDL), interleukin-6 (IL-6) and tumor necrosis factor α (TNF α) radiation were used to establish human vascular smooth muscle cells (VSMCs) in vitro model. Cell proliferation was determined by Cell Counting Kit-8 (CCK-8) assay. The apoptosis rate was determined by flow cytometry (FACS) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL) staining. The expression levels of Forkhead box protein F1 (FOXF1), B cell lymphoma-2 (Bcl-2) and BCL2-Associated X (Bax) were detected by qRT-PCR. Luciferase gene reporter and RNA pull down experiments confirmed the relationship between HCG11 and miR-144, miR-144 and FOXF1.

RESULTS

This study showed that HCG11 was significantly upregulated in patients with AS, while miR-144 was down-regulated in patients with AS. Ox-LDL and IL-6 in VSMCs induced up-regulation of HCG11 and down-regulation of miR-144. Overexpression of HCG11 promoted the proliferation and inhibited apoptosis of VSMCs. Luciferase gene reporter gene assay showed that HCG11 could bind to miR-144, and miR-144 could bind to FOXF1. Overexpression of miR-144 reversed the effect of HCG11 on VSMCs.

CONCLUSIONS

LncRNA HCG11 regulates proliferation and apoptosis of vascular smooth muscle cell through targeting miR-144-3p/FOXF1 axis.

Amorphous silica nanoparticles accelerated atherosclerotic lesion progression in ApoE-/- mice through endoplasmic reticulum stress-mediated CD36 up-regulation in macrophage

Background

The biosafety concern of silica nanoparticles (SiNPs) is rapidly expanding alongside with its mass production and extensive applications. The cardiovascular effects of SiNPs exposure have been gradually confirmed, however, the interaction between SiNPs exposure and atherosclerosis, and the underlying mechanisms still remain unknown. Thereby, this study aimed to explore the effects of SiNPs on the progression of atherosclerosis, and to investigate related mechanisms.

Results

We firstly investigated the in vivo effects of SiNPs exposure on atherosclerosis via intratracheal instillation of ApoE^−/− mice fed a Western diet. Ultrasound microscopy showed a significant increase of pulse wave velocity (PWV) compared to the control group, and the histopathological investigation reflected a greater plaque burden in the aortic root of SiNPs-exposed ApoE^−/− mice. Compared to the control group, the serum levels of total triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) were elevated after SiNPs exposure. Moreover, intensified macrophage infiltration and endoplasmic reticulum (ER) stress was occurred in plaques after SiNPs exposure, as evidenced by the upregulated CD68 and CHOP expressions. Further in vitro, SiNPs was confirmed to activate ER stress and induce lipid accumulation in mouse macrophage, RAW264.7. Mechanistic analyses showed that 4-PBA (a classic ER stress inhibitor) pretreatment greatly alleviated SiNPs-induced macrophage lipid accumulation, and reversed the elevated CD36 expression induced by SiNPs.

Conclusions

Our results firstly revealed the acceleratory effect of SiNPs on the progression of atherosclerosis in ApoE^−/− mice, which was related to lipid accumulation caused by ER stress-mediated upregulation of CD36 expression in macrophage.

Graphical abstract

Carotid intraplaque haemorrhage: pathogenesis, histological classification, imaging methods and clinical value

Vulnerable carotid atherosclerotic plaques are characterised by several risk factors, such as inflammation, neovascularization and intraplaque haemorrhage (IPH). Vulnerable plaques can lead to ischemic events such as stroke. Many studies reported a relationship between IPH, plaque rupture, and ischemic stroke. Histology is the gold standard to evaluate IPH, but it required carotid endarterectomy (CEA) surgery to collect the tissue sample. In this context, several imaging methods can be used as a non-invasive way to evaluate plaque vulnerability and detect IPH. Most imaging studies showed that IPH is associated with plaque vulnerability and stroke, with magnetic resonance imaging (MRI) being the most sensitive and specific to detect IPH as a predictor of ischemic events. These conclusions are however still debated because of the limited number of patients included in these studies; further studies are required to better assess risks associated with different IPH stages. Moreover, IPH is implicated in plaque vulnerability with other risk factors which need to be considered to predict ischemic risk. In addition, MRI sequences standardization is required to compare results from different studies and agree on biomarkers that need to be considered to predict plaque rupture. In these circumstances, IPH detection by MRI could be an efficient clinical method to predict stroke. The goal of this review article is to first describe the pathophysiological process responsible for IPH, its histological detection in carotid plaques and its correlation with plaque rupture. The second part will discuss the benefits and limitations of imaging the carotid plaque, and finally the clinical interest of imaging IPH to predict plaque rupture, focusing on MRI-IPH.

A Translational Mouse Model for NASH with Advanced Fibrosis and Atherosclerosis Expressing Key Pathways of Human Pathology

Non-alcoholic steatohepatitis (NASH) is a fast-growing liver disorder that is associated with an increased incidence of cardiovascular disease and type 2 diabetes. Animal models adequately mimicking this condition are scarce. We herein investigate whether Ldlr−/−. Leiden mice on different high-fat diets represent a suitable NASH model. Ldlr−/−. Leiden mice were fed a healthy chow diet or fed a high-fat diet (HFD) containing lard or a fast food diet (FFD) containing milk fat. Additionally, the response to treatment with obeticholic acid (OCA) was evaluated. Both high-fat diets induced obesity, hyperlipidemia, hyperinsulinemia, and increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Mice on both diets developed progressive macro- and microvesicular steatosis, hepatic inflammation, and fibrosis, along with atherosclerosis. HFD induced more severe hyperinsulinemia, while FFD induced more severe hepatic inflammation with advanced (F3) bridging fibrosis, as well as more severe atherosclerosis. OCA treatment significantly reduced hepatic inflammation and fibrosis, and it did not affect atherosclerosis. Hepatic transcriptome analysis was compared with human NASH and illustrated similarity. The present study defines a translational model of NASH with progressive liver fibrosis and simultaneous atherosclerosis development. By adaptation of the fat content of the diet, either insulin resistance (HFD) or hepatic inflammation and fibrosis (FFD) can be aggravated.

Vascular Remodeling and Immune Cell Infiltration in Splenic Artery Aneurysms

Rupture of splenic artery aneurysms (SAAs) is associated with a high mortality rate. The aim of this study was to identify the features of SAAs. Tissue sections from SAAs were compared to nonaneurysmal splenic arteries using various stains. The presence of intraluminal thrombus (ILT), vascular smooth muscle cells (VSMCs), cluster of differentiation (CD)-68+ phagocytes, myeloperoxidase+ neutrophils, CD3+, and CD20+ adaptive immune cells were studied using immunofluorescence microscopy. Analysis of SAAs revealed the presence of atherosclerotic lesions, calcifications, and ILT. Splenic artery aneurysms were characterized by a profound vascular remodeling with a dramatic loss of VSMCs, elastin degradation, adventitial fibrosis associated with enhanced apoptosis, and increased matrix metalloproteinase 9 expression. We observed an infiltration of immune cells comprising macrophages, neutrophils, T, and B cells. The T and B cells were found in the adventitial layer of SAAs, but their organization into tertiary lymphoid organs was halted. We failed to detect germinal centers even in the most organized T/B cell follicles and these lymphoid clusters lacked lymphoid stromal cells. This detailed histopathological characterization of the vascular remodeling during SAA showed that lymphoid neogenesis was incomplete, suggesting that critical mediators of their development must be missing.

Atherosclerotic Plaque Tissue Characterization: An OCT-Based Machine Learning Algorithm With ex vivo Validation

There is a need to develop a validated algorithm for plaque characterization which can help to facilitate the standardization of optical coherence tomography (OCT) image interpretation of plaque morphology, and improve the efficiency and accuracy in the application of OCT imaging for the quantitative assessment of plaque vulnerability. In this study, a machine learning algorithm was implemented for characterization of atherosclerotic plaque components by intravascular OCT using ex vivo carotid plaque tissue samples. A total of 31 patients underwent carotid endarterectomy and the ex vivo carotid plaques were imaged with OCT. Optical parameter, texture features and relative position of pixels were extracted within the region of interest and then used to quantify the tissue characterization of plaque components. The potential of individual and combined feature set to discriminate tissue components was quantified using sensitivity, specificity, accuracy. The results show there was a lower classification accuracy in the calcified tissue than the fibrous tissue and lipid tissue. The pixel-wise classification accuracy obtained by the developed method, to characterize the fibrous, calcified and lipid tissue by comparing with histology, were 80.0, 62.0, and 83.1, respectively. The developed algorithm was capable of characterizing plaque components with an excellent accuracy using the combined feature set.

Skeletal muscle microvascular insulin resistance in type 2 diabetes is not improved by eight weeks of regular walking

We aimed to examine whether individuals with type 2 diabetes (T2D) exhibit suppressed leg vascular conductance and skeletal muscle capillary perfusion in response to a hyperinsulinemic-euglycemic clamp and to test whether these two variables are positively correlated. Subsequently, we examined whether T2D-associated skeletal muscle microvascular insulin resistance, as well as overall vascular dysfunction, would be ameliorated by an 8-wk walking intervention (45 min at 60% of heart rate reserve, 5 sessions/week). We report that, relative to healthy subjects, overweight and obese individuals with T2D exhibit depressed insulin-stimulated increases in leg vascular conductance, skeletal muscle capillary perfusion, and Akt phosphorylation. Notably, we found that within individuals with T2D, those with lesser increases in leg vascular conductance in response to insulin exhibited the lowest increases in muscle capillary perfusion, suggesting that limited muscle capillary perfusion may be, in part, linked to the impaired ability of the upstream resistance vessels to dilate in response to insulin. Furthermore, we show that the 8-wk walking intervention, which did not evoke weight loss, was insufficient to ameliorate skeletal muscle microvascular insulin resistance in previously sedentary, overweight/obese subjects with T2D, despite high adherence and tolerance. However, the walking intervention did improve (P < 0.05) popliteal artery flow-mediated dilation (+4.52%) and reduced HbA1c (-0.75%). It is possible that physical activity interventions that are longer in duration, engage large muscle groups with recruitment of the maximum number of muscle fibers, and lead to a robust reduction in metabolic risk factors may be required to overhaul microvascular insulin resistance in T2D.NEW & NOTEWORTHY This report provides evidence that in sedentary subjects with type 2 diabetes diminished insulin-stimulated increases in leg vascular conductance and ensuing blunted capillary perfusion in skeletal muscle are not restorable by increased walking alone. More innovative physical activity interventions that ultimately result in a robust mitigation of metabolic risk factors may be vital for reestablishing skeletal muscle microvascular insulin sensitivity in type 2 diabetes.

Dare to Compare. Development of Atherosclerotic Lesions in Human, Mouse, and Zebrafish

Cardiovascular diseases, such as atherosclerosis, are the leading cause of death worldwide. Although mice are currently the most commonly used model for atherosclerosis, zebrafish are emerging as an alternative, especially for inflammatory and lipid metabolism studies. Here, we review the history of in vivo atherosclerosis models and highlight the potential for future studies on inflammatory responses in lipid deposits in zebrafish, based on known immune reactions in humans and mice, in anticipation of new zebrafish models with more advanced atherosclerotic plaques.

Cardiovascular Prevention: Migrating From a Binary to a Ternary Classification

Migrating from a binary approach to risk assessment to a ternary model of disease identification allows for individualized, optimal disease management. Redefining the disease/inflammatory approach has been proven to identify, stabilize, and regress atherosclerosis while adding understanding to the progression of vascular disease. Our previously published results show the beneficial effect of comprehensive, evidence-based management on subclinical atherosclerosis and vulnerable plaque. We argue that this approach does not mitigate the value of utilizing standard risk factor identification, but rather augments it for the benefit of the individual patient.

CD4+/CD8+ ratio positively correlates with coronary plaque instability in unstable angina pectoris patients but fails to predict major adverse cardiovascular events

Background:

The association between CD4+/CD8+ ratio and coronary plaque instability in patients with unstable angina pectoris (UAP) has not been investigated. We sought to elucidate the correlation between CD4+/CD8+ ratio and plaque instability in this patient population.

Methods:

We enrolled 266 UAP patients who underwent pre-intervention optical coherence tomography (OCT) examination and percutaneous coronary intervention in our center from January 2016 to January 2018. Features of coronary plaques in the culprit arteries were classified as unstable plaque and stable plaque. Primary endpoint was occurrence of a major adverse cardiovascular event (MACE). Receiver operating characteristic (ROC) analyses were used to determine the predictive efficacy of the CD4+/CD8+ ratio for a group of unstable plaque patients, and binary logistic regression analysis was performed to evaluate potential independent predictors of plaque instability. All-cause mortality and MACE between the two groups were analyzed.

Results:

UAP patients with unstable plaque had a higher CD4/CD8 ratio compared with stable plaque patients (p < 0.05). Results of binary logistic regression analyses showed that CD4+/CD8+ ratio ⩾1.725 and prior stroke were predictors and risk factors of plaque instability (p < 0.05). ROC analyses showed that CD4+/CD8+ ratio ⩾1.725 was predictive of plaque instability in UAP patients. However, the Kaplan–Meier estimate for MACE and all-cause mortality showed no statistical significance.

Conclusions:

Higher CD4+/CD8+ ratio is associated with higher risk of plaque instability in our cohort of UAP patients. However, CD4+/CD8+ ratio was not an independent predictor of 1-year MACE or all-cause mortality.

Accelerated miniature swine models of advanced atherosclerosis: A review based on morphology

In order to accelerate development of atherosclerosis(AS) in miniature swine models, varieties of strategies and methods have been explored. In addition to traditional methods such as high cholesterol feeding and balloon injury, new methods such as familial hypercholesterolemia induced by gene editing and intramural injection have been applied in recent years. Although it has been claimed that these methods have successfully aggravated lesion areas and stenosis, lesion features induced by different strategies have shown heterogeneity in morphology. In addition, time consumption, high cost, and unavailability are problems that restrict application of these AS models. Here, we summarize strategies and methods to accelerate AS models and further analyze their values, advantages, and shortcomings.

Macrophage NCOR1 protects from atherosclerosis by repressing a pro-atherogenic PPARγ signature

AIMS

Nuclear receptors and their cofactors regulate key pathophysiological processes in atherosclerosis development. The transcriptional activity of these nuclear receptors is controlled by the nuclear receptor corepressors (NCOR), scaffolding proteins that form the basis of large corepressor complexes. Studies with primary macrophages demonstrated that the deletion of Ncor1 increases the expression of atherosclerotic molecules. However, the role of nuclear receptor corepressors in atherogenesis is unknown.

METHODS AND RESULTS

We generated myeloid cell-specific Ncor1 knockout mice and crossbred them with low-density lipoprotein receptor (Ldlr) knockouts to study the role of macrophage NCOR1 in atherosclerosis. We demonstrate that myeloid cell-specific deletion of nuclear receptor corepressor 1 (NCOR1) aggravates atherosclerosis development in mice. Macrophage Ncor1-deficiency leads to increased foam cell formation, enhanced expression of pro-inflammatory cytokines, and atherosclerotic lesions characterized by larger necrotic cores and thinner fibrous caps. The immunometabolic effects of NCOR1 are mediated via suppression of peroxisome proliferator-activated receptor gamma (PPARγ) target genes in mouse and human macrophages, which lead to an enhanced expression of the CD36 scavenger receptor and subsequent increase in oxidized low-density lipoprotein uptake in the absence of NCOR1. Interestingly, in human atherosclerotic plaques, the expression of NCOR1 is reduced whereas the PPARγ signature is increased, and this signature is more pronounced in ruptured compared with non-ruptured carotid plaques.

CONCLUSIONS

Our findings show that macrophage NCOR1 blocks the pro-atherogenic functions of PPARγ in atherosclerosis and suggest that stabilizing the NCOR1-PPARγ binding could be a promising strategy to block the pro-atherogenic functions of plaque macrophages and lesion progression in atherosclerotic patients.

Carotid plaque magnetic resonance imaging and recurrent stroke risk: A systematic review and meta-analysis

BACKGROUND

MRI findings of carotid plaque components have been studied recently as a tool to predict recurrent ischemic events. We performed a systematic review and meta-analysis to summarize the association of MRI-determined intraplaque hemorrhage, lipid-rich necrotic core, and thinning/rupture of the fibrous cap with recurrent ischemic events.

METHODS

Electronic search was performed in PUBMED, EMBASE, Cochrane Controlled Register of Trials (CENTRAL) from inception to Oct 30, 2018. We included cohort studies with an average follow-up time of more than 1 month in which intraplaque hemorrhage, lipid-rich necrotic core, or thinning/rupture of the fibrous cap were associated with recurrent ipsilateral stroke or ischemic events. We performed heterogeneity assessment before carrying out meta-analysis. According to the heterogeneity, we selected fixed-effect model for meta-analysis of the included cohort studies.

RESULTS

Using a prespecified search strategy, of the 2128 articles, 6 studies with a total number of 621 participants met eligibility for systematic review and meta-analysis. The hazard ratios of intra-plaque hemorrhage, thinning/rupture of the fibrous cap and lipid rich necrotic core as recurrent Stroke/Transient ischemic attack (TIA) were 7.14(95% confidence interval, 4.32 to 11.82), 5.68(95% confidence interval, 2.40 to 13.47), and 2.73(95% confidence interval, 1.04 to 7.16), respectively. No significant heterogeneity was found in the 3 meta-analyses.

CONCLUSIONS

The presence of intraplaque hemorrhage, lipid-rich necrotic core, and thinning/rupture of the fibrous cap on MRI of carotid plaque are strong predictors of recurrent stroke events. However, due to the lack of original studies, larger cohort studies are warranted.

Innovators in atherosclerosis research: A historical review

This review presents a retrospective analysis of the significance of the contributions of pathologists and kindred investigators in the latter half of the twentieth century to the advancement of understanding of atherosclerosis, a major disease and affliction of humankind. These outstanding investigators contributed importantly to the development of a large body of evidence encompassing population-based autopsy studies, experimental animal studies and cell biological investigations that, coupled with insights from epidemiological studies, serve as the underpinning for the current dominant response to injury theory of atherogenesis. Their collective contributions have been highly meritorious and will remain seminally important into the future.

Biglycan and atherosclerosis: Lessons from high cardiovascular risk conditions

Atherosclerosis (ATH) is a chronic, dynamic, evolutive process involving morphological and structural subversion of artery walls, leading to the formation of atherosclerotic plaques. ATH generally initiates during the childhood, occurring as a result of a number of changes in the intima tunica and in the media of arteries. A key event occurring during the pathobiology of ATH is the accumulation of lipoproteins in the sub-intimal spaces mediated by extracellular matrix (ECM) molecules, especially by the chondroitin sulfate/dermatan sulfate (CS/DS) -containing proteoglycans (CS/DSPGs). Among them, the proteoglycan biglycan (BGN) is critically involved in the onset and progression of ATH and evidences show that BGN represents the missing link between the pro-atherogenic status induced by both traditional and non-traditional cardiovascular risk factors and the development and progression of vascular damage. In the light of these findings, the role of BGN in dyslipidemia, hypertension, cigarette smoking, diabetes, chronic kidney disease and inflammatory status is briefly analyzed and discussed in order to shed new light on the underlying mechanisms governing the association between BGN and ATH.

Slug, a Cancer-Related Transcription Factor, is Involved in Vascular Smooth Muscle Cell Transdifferentiation Induced by Platelet-Derived Growth Factor-BB During Atherosclerosis

Background Heart attacks and stroke often result from occlusive thrombi following the rupture of vulnerable atherosclerotic plaques. Vascular smooth muscle cells (VSMCs) play a pivotal role in plaque vulnerability because of their switch towards a proinflammatory/macrophage-like phenotype when in the context of atherosclerosis. The prometastatic transcription factor Slug/Snail2 is a critical regulator of cell phenotypic transition. Here, we aimed to investigate the role of Slug in the transdifferentiation process of VSMCs occurring during atherogenesis. Methods and Results In rat and human primary aortic smooth muscle cells, Slug protein expression is strongly and rapidly increased by platelet-derived growth factor-BB (PDGF-BB). PDGF-BB increases Slug protein without affecting mRNA levels indicating that this growth factor stabilizes Slug protein. Immunocytochemistry and subcellular fractionation experiments reveal that PDGF-BB triggers a rapid accumulation of Slug in VSMC nuclei. Using pharmacological tools, we show that the PDGF-BB-dependent mechanism of Slug stabilization in VSMCs involves the extracellular signal-regulated kinase 1/2 pathway. Immunohistochemistry experiments on type V and type VI atherosclerotic lesions of human carotids show smooth muscle-specific myosin heavy chain-/Slug-positive cells surrounding the prothrombotic lipid core. In VSMCs, Slug siRNAs inhibit prostaglandin E2 secretion and prevent the inhibition of cholesterol efflux gene expression mediated by PDGF-BB, known to be involved in plaque vulnerability and/or thrombogenicity. Conclusions Our results highlight, for the first time, a role of Slug in aortic smooth muscle cell transdifferentiation and enable us to consider Slug as an actor playing a role in the atherosclerotic plaque progression towards a life-threatening phenotype. This also argues for common features between acute cardiovascular events and cancer.

Stress-Only Adenosine CMR Improves Diagnostic Yield in Stable Symptomatic Patients With Coronary Artery Calcium

OBJECTIVES

This study assessed whether adenosine stress-only perfusion cardiac magnetic resonance (CMR) following a positive coronary artery calcium (CAC) score improved the diagnostic yield of invasive coronary angiography (CAG) in patients with stable chest pain. The study also established the association between positive CAC scores and stress-induced myocardial ischemia.

BACKGROUND

The diagnostic yield of catheterization among patients with suspected coronary artery disease (CAD) is low. Improved patient selection and diagnostic testing are necessary. The CAC score can minimize unnecessary diagnostic testing, and in low-risk patients, normal CMR results have a high negative predictive value. Less comprehensive protocols may be sufficient to guide further work-up.

METHODS

A total of 642 consecutive patients (mean age: 63 years; 50% women) with stable chest pain and CAC scores of >0 who were referred for CMR were enrolled. Patients with a perfusion defect were subsequently examined by CAG. Patients were followed up for 1 year. Outcome was obstructive CAD.

RESULTS

Obstructive CAD was present in 12% of patients. For CAD diagnosis, the sensitivity of adenosine CMR was 90.9% (95% confidence interval [CI]: 88.7 to 93.1), specificity was 98.7% (95% CI: 97.9 to 99.6), positive predictive value was 92.0% (95% CI: 89.8 to 94.1), and negative predictive value was 98.6% (95% CI: 97.6 to 99.5). A CAC score between 0.1 and 100 without typical angina was associated with obstructive CAD in only 3% of patients. Patients with nonanginal chest pain and a CAC score ≥400 had obstructive CAD (16%).

CONCLUSIONS

Stress-only adenosine CMR had high diagnostic accuracy and served as an efficient gatekeeper to CAG in stable patients with a CAC score >0. Patients with CAC scores between 0.1 and 100 could be deferred from further testing in the absence of clinical features that suggested high risk. However, in patients with CAC score ≥400, functional testing should be indicated, regardless of the type of chest pain.

FURIN Inhibition Reduces Vascular Remodeling and Atherosclerotic Lesion Progression in Mice

Objective- Atherosclerotic coronary artery disease is the leading cause of death worldwide, and current treatment options are insufficient. Using systems-level network cluster analyses on a large coronary artery disease case-control cohort, we previously identified PCSK3 (proprotein convertase subtilisin/kexin family member 3; FURIN) as a member of several coronary artery disease-associated pathways. Thus, our objective is to determine the role of FURIN in atherosclerosis. Approach and Results- In vitro, FURIN inhibitor treatment resulted in reduced monocyte migration and reduced macrophage and vascular endothelial cell inflammatory and cytokine gene expression. In vivo, administration of an irreversible inhibitor of FURIN, α-1-PDX (α1-antitrypsin Portland), to hyperlipidemic Ldlr^-/- mice resulted in lower atherosclerotic lesion area and a specific reduction in severe lesions. Significantly lower lesional macrophage and collagen area, as well as systemic inflammatory markers, were observed. MMP2 (matrix metallopeptidase 2), an effector of endothelial function and atherosclerotic lesion progression, and a FURIN substrate was significantly reduced in the aorta of inhibitor-treated mice. To determine FURIN's role in vascular endothelial function, we administered α-1-PDX to Apoe^-/- mice harboring a wire injury in the common carotid artery. We observed significantly decreased carotid intimal thickness and lower plaque cellularity, smooth muscle cell, macrophage, and inflammatory marker content, suggesting protection against vascular remodeling. Overexpression of FURIN in this model resulted in a significant 67% increase in intimal plaque thickness, confirming that FURIN levels directly correlate with atherosclerosis. Conclusions- We show that systemic inhibition of FURIN in mice decreases vascular remodeling and atherosclerosis. FURIN-mediated modulation of MMP2 activity may contribute to the atheroprotection observed in these mice.

Spotty Calcium on Cervicocerebral Computed Tomography Angiography Associates With Increased Risk of Ischemic Stroke

Background and Purpose- Cervicocerebral vascular calcification on computed tomography angiography is a known sign of advanced atherosclerosis. However, the clinical significance of calcification pattern remains unclear. In this study, we aimed to investigate the potential association between spotty calcium and acute ischemic stroke. Methods- This study included patients with first-time nonlacunar ischemic stroke (N=50) confirmed by brain magnetic resonance imaging or nonenhanced head computed tomography, as well as control subjects with asymptomatic carotid atherosclerosis (N=50) confirmed by carotid ultrasonography. Subjects in both groups underwent contrast-enhanced cervicocerebral computed tomography angiography within a week after the initial imaging examination. Spotty calcification was evaluated at 11 arterial segments commonly affected by atherosclerosis along the carotid and vertebrobasilar circulation. Statistical analysis was performed comparing the frequency and spatial pattern of spotty calcification between the 2 groups. Results- Spotty calcification in the Stroke group was markedly more prevalent than that in the Control group (total SC count: 8.74±4.96 versus 1.84±1.82, P<0.001). The odds ratio (95% CI) for stroke was 2.49 (1.55-4.00) for spotty calcification at bilateral carotid bifurcation, 1.52 (1.13-2.04) at carotid siphon, and 1.98 (1.45-2.69) at all evaluated locations. A total number of 3 spotty calcifications were determined as the optimal cutoff threshold for increased risk of stroke. Spotty calcium showed significantly greater area under the receiver operating characteristics curve than total calcium volume irrespective of size (0.88 versus 0.77). Within the Stroke group, ipsilateral lateral side showed significantly more spotty calcium than the contralateral side (5.18±3.05 versus 3.56±2.67, P<0.001). Conclusions- Nonlacunar ischemia stroke was associated with markedly increased incidence of spotty calcification with a distinct spatial pattern on cervicocerebral computed tomography compared with subclinical atherosclerosis, suggesting the potential role of spotty calcification for improving the risk stratification for ischemic stroke.

Diet-induced leukocyte telomere shortening in a baboon model for early stage atherosclerosis

Reported associations between leukocyte telomere length (LTL) attrition, diet and cardiovascular disease (CVD) are inconsistent. This study explores effects of prolonged exposure to a high cholesterol high fat (HCHF) diet on LTL in a baboon model of atherosclerosis. We measured LTL by qPCR in pedigreed baboons fed a chow (n = 105) or HCHF (n = 106) diet for 2 years, tested for effects of diet on LTL, and association between CVD risk factors and atherosclerotic lesions with LTL. Though not different at baseline, after 2 years median LTL is shorter in HCHF fed baboons (P < 0.0001). Diet predicts sex- and age-adjusted LTL and LTL attrition (P = 0.0009 and 0.0156, respectively). Serum concentrations of CVD biomarkers are associated with LTL at the 2-year endpoint and LTL accounts approximately 6% of the variance in aortic lesions (P = 0.04). Although heritable at baseline (h² = 0.27, P = 0.027) and after 2 years (h² = 0.46, P = 0.0038), baseline LTL does not predict lesion extent after 2 years. Atherogenic diet influences LTL, and LTL is a potential biomarker for early atherosclerosis. Prolonged exposure to an atherogenic diet decreases LTL and increases LTL attrition, and shortened LTL is associated with early-stage atherosclerosis in pedigreed baboons.