Smooth muscle cell phenotypic switch: implications for foam cell formation

A critical appreciation of pathway analysis in atherosclerotic disease. Cellular phenotypic plasticity as an illustrative example

The rapid advancements in genome-scale (omics) techniques has created significant opportunities to investigate complex disease mechanisms in tissues and cells. Nevertheless, interpreting -omics data can be challenging, and pathway enrichment analysis is a frequently used method to identify candidate molecular pathways that drive gene expression changes. With a growing number of -omics studies dedicated to atherosclerosis, there has been a significant increase in studies and hypotheses relying on enrichment analysis. This brief review discusses the benefits and limitations of pathway enrichment analysis within atherosclerosis research. We highlight the challenges of identifying complex biological processes, such as cell phenotypic switching, within -omics data. Additionally, we emphasize the need for more comprehensive and curated gene sets that reflect the biological complexity of atherosclerosis. Pathway enrichment analysis is a valuable tool for gaining insights into the molecular mechanisms of atherosclerosis. Nevertheless, it is crucial to remain aware of the intrinsic limitations of this approach. By addressing these weaknesses, enrichment analysis in atherosclerosis can lead to breakthroughs in identifying the mechanisms of disease progresses, the identification of key driver genes, and consequently, advance personalized patient care.

Single-nucleus RNA sequencing reveals that macrophages and smooth muscle cells promote carotid atherosclerosis progression through mitochondrial autophagy

Carotid atherosclerotic plaques are the manifestation of atherosclerosis in the carotid arteries and can significantly increase the incidence of cerebrovascular disease. Macrophages and smooth muscle cells are crucial for their development. To reveal the mechanism of carotid atherosclerotic plaque formation, we performed single-nucleus RNA sequencing of the carotid plaque tissue and identified 11 cell types, and the macrophages were divided into 5 different macrophage subpopulations. The macrophages and smooth muscle cells in the patients with symptomatic carotid atherosclerotic plaques caused intraplaque cell death via the mitochondrial autophagic pathway, resulting in plaque instability and rupture, which in turn led to clinical cardiovascular and cerebrovascular events. The findings provide new insights into carotid atherosclerosis formation, and this may provide new directions for the prevention and treatment of carotid atherosclerosis.

Hypermethylation of the CTRP9 promoter region promotes Hcy induced VSMC lipid deposition and foam cell formation via negatively regulating ER stress

To provide a theoretical basis for the prevention and treatment of atherosclerosis (As), the current study aimed to investigate the mechanism underlying the effect of homocysteine (Hcy) on inducing the lipid deposition and foam cell formation of the vascular smooth muscle cell (VSMC) via C1q/Tumor necrosis factor-related protein9 (CTRP9) promoter region Hypermethylation negative regulating endoplasmic reticulum stress (ERs). Therefore, apolipoprotein E deficient (ApoE-/-) mice were randomly divided into the control [ApoE-/- + normal diet (NC)] and high methionine [ApoE-/- + (normal diet supplemented with 1.7% methionine (HMD)] groups (n = 6 mice/group). Following feeding for 15 weeks, the serum levels of Homocysteine (Hcy), total cholesterol (TC), and triglyceride (TG) were measured using an automatic biochemical analyzer. HE and oil red O staining were performed on the aorta roots to observe the pathological changes. Additionally, immunofluorescence staining was performed to detect the protein expression levels of CTRP9, glucose-regulated protein 78 kD (GRP78), phosphorylated protein kinase RNA-like ER kinase (p-PERK), activating transcription factor 6a (ATF6a), phosphorylated inositol-requiring enzyme-1α (p-IRE1α), sterol regulatory element binding proteins-1c (SREBP1c) and sterol regulatory element binding proteins-2 (SREBP2) in VSMC derived from murine aortic roots. In vitro, VSMC was stimulated with 100 μmol/l Hcy. After transfection of plasmids with overexpression and interference of CTRP9, ERs agonist (TM) and inhibitor (4-PBA) were given to stimulate VSMC cells. HE staining and oil red O staining were used to observe the effect of Hcy stimulation on lipid deposition in VSMC. Additionally, The mRNA and protein expression levels of CTRP9, GRP78, PERK, ATF6a, IRE1α, SREBP1c, and SREBP2 in VSMC were detected by RT-qPCR and western blot analysis, respectively. Finally, The methylation modification of the CTRP9 promoter region has been studied. The NCBI database was used to search the promoter region of the CTRP9 gene, and CpG Island was used to predict the methylation site. After Hcy stimulation of VSMC, overexpression of DNMT1, and intervention with 5-Azc, assess the methylation level of the CTRP9 promoter through bisulfite sequencing PCR (BSP). The results showed that the serum levels of Hcy, TC, and TG in the ApoE-/- + HMD group were significantly increased compared with the ApoE-/- + NC group. In addition, HE staining and oil red O staining showed obvious AS plaque formation in the vessel wall, and a large amount of fat deposition in VSMC, thus indicating that the hyperhomocysteinemia As an animal model was successfully established. Furthermore, CTRP9 were downregulated, while GRP78, p-PERK, ATF6a, p-IRE1α, SREBP1c, SREBP2 was upregulated in aortic VSMC in the ApoE-/- + HMD group. Consistent with the in vivo results, Hcy can inhibit the expression of CTRP9 in VSMC and induce ERs and lipid deposition in VSMC. Meanwhile, the increased expression of CTRP9 can reduce ERs and protect the lipid deposition in Hcy induced VSMC. Furthermore, ERs can promote Hcy induced VSMC lipid deposition, inhibition of ERs can reduce Hcy induced VSMC lipid deposition, and CTRP9 may play a protective role in Hcy induced VSMC lipid deposition and foam cell transformation through negative regulation of ERs. In addition, The CTRP9 promoter in the Hcy group showed hypermethylation. At the same time as Hcy intervention, overexpression of DNMT1 increases the methylation level of the CTRP9 promoter, while 5-Azc can reduce the methylation level of the CTRP9 promoter. Finally, Hcy can up-regulate the expression of DNMT1 and down-regulate the expression of CTRP9. After overexpression of DNMT1, the expression of CTRP9 is further decreased. After 5-Azc inhibition of DNMT1, the expression of DNMT1 decreases, while the expression of CTRP9 increases. It is suggested that the molecular mechanism of Hcy inhibiting the expression of CTRP9 is related to the hypermethylation of the CTRP9 promoter induced by Hcy and regulated by DNMT1. 5-Azc can inhibit the expression of DNMT1 and reverse the regulatory effect of DNMT1 on CTRP9. Overall, the results of the present study suggested that Hcy induces DNA hypermethylation in the CTRP9 promoter region by up-regulating DNMT1 expression, and negatively regulates ERs mediated VSMC lipid deposition and foam cell formation. CTRP9 may potentially be a therapeutic target in the treatment of hyperhomocysteinemia and As.

Female Gene Networks Are Expressed in Myofibroblast-Like Smooth Muscle Cells in Vulnerable Atherosclerotic Plaques

BACKGROUND

Women presenting with coronary artery disease more often present with fibrous atherosclerotic plaques, which are currently understudied. Phenotypically modulated smooth muscle cells (SMCs) contribute to atherosclerosis in women. How these phenotypically modulated SMCs shape female versus male plaques is unknown.

METHODS

Gene regulatory networks were created using RNAseq gene expression data from human carotid atherosclerotic plaques. The networks were prioritized based on sex bias, relevance for smooth muscle biology, and coronary artery disease genetic enrichment. Network expression was linked to histologically determined plaque phenotypes. In addition, their expression in plaque cell types was studied at single-cell resolution using single-cell RNAseq. Finally, their relevance for disease progression was studied in female and male Apoe-/- mice fed a Western diet for 18 and 30 weeks.

RESULTS

Here, we identify multiple sex-stratified gene regulatory networks from human carotid atherosclerotic plaques. Prioritization of the female networks identified 2 main SMC gene regulatory networks in late-stage atherosclerosis. Single-cell RNA sequencing mapped these female networks to 2 SMC phenotypes: a phenotypically modulated myofibroblast-like SMC network and a contractile SMC network. The myofibroblast-like network was mostly expressed in plaques that were vulnerable in women. Finally, the mice ortholog of key driver gene MFGE8 (milk fat globule EGF and factor V/VIII domain containing) showed retained expression in advanced plaques from female mice but was downregulated in male mice during atherosclerosis progression.

CONCLUSIONS

Female atherosclerosis is characterized by gene regulatory networks that are active in fibrous vulnerable plaques rich in myofibroblast-like SMCs.

FAM3A mediates the phenotypic switch of human aortic smooth muscle cells stimulated with oxidised low-density lipoprotein by influencing the PI3K-AKT pathway

Family with sequence similarity 3 member A (FAM3A) is a multifunctional protein that is related to the pathological process of various disorders. FAM3A is reportedly able to affect the phenotypic change of vascular smooth muscle cells under a hypertensive state. Whether FAM3A mediates the phenotypic switch of vascular smooth muscle cells under an atherosclerotic state remains unaddressed. This work investigated the roles and mechanisms of FAM3A in mediating the phenotypic switch of human aortic smooth muscle cells (HASMCs) stimulated with oxidised low-density lipoprotein (ox-LDL) in vitro. FAM3A expression was elevated in HASMCs following ox-LDL treatment. FAM3A silencing led to a suppressive effect on ox-LDL-provoked proliferation, migration and inflammation of HASMCs, whereas FAM3A overexpression had an opposite effect. Ox-LDL elicited a change in HASMCs from a contractile phenotype to a synthetic phenotype, which was inhibited by FAM3A silencing or enhanced by FAM3A overexpression. Further investigation elucidated that FAM3A silencing repressed and FAM3A overexpression promoted ox-LDL-induced activation of the PI3K-AKT pathway in HASMCs. Reactivation of AKT reversed the suppressive effect of FAM3A silencing on the ox-LDL-induced phenotypic switch of HASMCs. Restraining AKT blocked the promoting effect of FAM3A overexpression on the ox-LDL-induced phenotypic switch of HASMCs. In summary, this work elucidates that FAM3A mediates the ox-LDL-induced phenotypic switch of HASMCs by influencing the PI3K-AKT pathway, indicating a potential role for FAM3A in atherosclerosis.

Salusins: advance in cardiovascular disease research

Salusins are discovered in 2003 and divided into salusin-α and salusin-β, which are bioactive peptides with hemodynamic and mitotic activity and mainly distributed in plasma, urine, endocrine glands and kidneys. A large number of studies have shown that salusins can regulate lipid metabolism, inflammatory response and vascular proliferation. Despite the profound and diverse physiological properties of salusins, the exact mechanism of their cardiovascular effects remains to be determined. The potential mechanisms of action of salusins in cardiovascular-related diseases such as atherosclerosis, hypertension, heart failure, myocardial infarction and myocarditis, and their use as biomarkers of cardiovascular disease are discussed. This review aims to provide a new strategy for the diagnosis and prevention of clinical cardiovascular diseases.

Female gene networks are expressed in myofibroblast-like smooth muscle cells in vulnerable atherosclerotic plaques

Women presenting with coronary artery disease (CAD) more often present with fibrous atherosclerotic plaques, which are currently understudied. Phenotypically modulated smooth muscle cells (SMCs) contribute to atherosclerosis in women. How these phenotypically modulated SMCs shape female versus male plaques is unknown. Here, we show sex-stratified gene regulatory networks (GRNs) from human carotid atherosclerotic tissue. Prioritization of these networks identified two main SMC GRNs in late-stage atherosclerosis. Single-cell RNA-sequencing mapped these GRNs to two SMC phenotypes: a phenotypically modulated myofibroblast-like SMC network and a contractile SMC network. The myofibroblast-like GRN was mostly expressed in plaques that were vulnerable in females. Finally, mice orthologs of the female myofibroblast-like genes showed retained expression in advanced plaques from female mice but were downregulated in male mice during atherosclerosis progression. Female atherosclerosis is driven by GRNs that promote a fibrous vulnerable plaque rich in myofibroblast-like SMCs.

Reconsidering the role of glycaemic control in cardiovascular disease risk in type 2 diabetes: A 21st century assessment

It is well known that the multiple factors contributing to the pathogenesis of type 2 diabetes (T2D) confer an increased risk of developing cardiovascular disease (CVD). Although the relationship between hyperglycaemia and increased microvascular risk is well established, the relative contribution of hyperglycaemia to macrovascular events has been strongly debated, particularly owing to the failure of attempts to reduce CVD risk through normalizing glycaemia with traditional therapies in high-risk populations. The debate has been further fuelled by the relatively recent discovery of the cardioprotective properties of glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter-2 inhibitors. Further, as guidelines now recommend individualizing glycaemic targets, highlighting the importance of achieving glycated haemoglobin (HbA1c) goals safely, the previously observed negative influences of intensive therapy on CVD risk might not present if trials were repeated using current-day treatments and individualized HbA1c goals. Emerging longitudinal data illuminate the overall effect of excess glucose, the impacts of magnitude and duration of hyperglycaemia on disease progression and risk of CVD complications, and the importance of glycaemic control at or early after diagnosis of T2D for prevention of complications. Herein, we review the role of glucose as a modifiable cardiovascular (CV) risk factor, the role of microvascular disease in predicting macrovascular risk, and the deleterious impact of therapeutic inertia on CVD risk. We reconcile new and old data to offer a current perspective, highlighting the importance of effective, early treatment in reducing latent CV risk, and the timely use of appropriate therapy individualized to each patient's needs.

Platelet membrane-cloaked selenium/ginsenoside Rb1 nanosystem as biomimetic reactor for atherosclerosis therapy

Cardiovascular disease remains the dominant contributor to human mortality, and the main etiology of which is atherosclerosis (AS). Enhancing the targeted ability of nanosystem and improving plaque stability are critical challenges for the current management of AS. Herein, we leverage the marked role of platelets in AS to construct a biomimetic nanodrug delivery system (PM@Se/Rb1 NPs), which prepared by cloaking platelet membrane (PM) around Selenium (Se) and ginsenoside Rb1 nanoparticles (Se/Rb1 NPs) core. The core endows the delivery system antioxidant, lipid metabolism and anti-inflammatory effects for AS effective treatment. Moreover, PM-coated nanoparticles reserve platelets' inherent biological elements to deliver drugs to plaques. We further explored the potential effect of PM@Se/Rb1 NPs' combination with the clinical anticoagulant drug warfarin (War) to treat AS and elucidated the possible drug interaction mechanism. As a result, the PM@Se/Rb1 NPs are not only capable of improving inflammatory behaviors such as inhibitory adhesion ability and anti-angiogenesis therapeutic effect in vitro, but also administer efficiently localizing to atherosclerotic plaque explaining by aortic samples from established ApoE^-/- mice. Therefore, this study provided a theoretical basis of biomimetic nanodrug in the treatment of AS as well as an effective reference for the combined application of nanodrug and clinical drugs.

Adverse outcome pathway of fine particulate matter leading to increased cardiovascular morbidity and mortality: An integrated perspective from toxicology and epidemiology

Fine particulate matter (PM_2.5) exposure is a major threat to public health, and is listed as one of the leading factors associated with global premature mortality. Among the adverse health effects on multiple organs or tissues, the influence of PM_2.5 exposure on cardiovascular system has drawn more and more attention. Although numerous studies have investigated the mechanisms responsible for the cardiovascular toxicity of PM_2.5, the various mechanisms have not been integrated due to the variety of the study models, different levels of toxicity assessment endpoints, etc. Adverse Outcome Pathway (AOP) framework is a useful tool to achieve this goal so as to facilitate comprehensive understanding of toxicity assessment of PM_2.5 on cardiovascular system. This review aims to illustrate the causal mechanistic relationships of PM_2.5-triggered cardiovascular toxicity from different levels (from molecular/cellular/organ to individual/population) by using AOP framework. Based on the AOP Wiki and published literature, we propose an AOP framework focusing on the cardiovascular toxicity induced by PM_2.5 exposure. The molecular initiating event (MIE) is identified as reactive oxygen species generation, followed by the key events (KEs) of oxidative damage and mitochondria dysfunction, which induces vascular endothelial dysfunction via vascular endothelial cell autophagy dysfunction, vascular fibrosis via vascular smooth muscle cell activation, cardiac dysregulation via myocardial apoptosis, and cardiac fibrosis via fibroblast proliferation and myofibroblast differentiation, respectively; all of the above cardiovascular injuries ultimately elevate cardiovascular morbidity and mortality in the general population. As far as we know, this is the first work on PM_2.5-related cardiovascular AOP construction. In the future, more work needs to be done to explore new markers in the safety assessment of cardiovascular toxicity induced by PM_2.5.

Nanobiotechnology approaches for cardiovascular diseases: site-specific targeting of drugs and nanoparticles for atherothrombosis

Atherosclerosis and atherothrombosis, the major contributors to cardiovascular diseases (CVDs), represent the leading cause of death worldwide. Current pharmacological therapies have been associated with side effects or are insufficient at halting atherosclerotic progression effectively. Pioneering work harnessing the passive diffusion or endocytosis properties of nanoparticles and advanced biotechnologies in creating recombinant proteins for site-specific delivery have been utilized to overcome these limitations. Since CVDs are complex diseases, the most challenging aspect of developing site-specific therapies is the identification of an individual and unique antigenic epitope that is only expressed in lesions or diseased areas. This review focuses on the pathological mechanism of atherothrombosis and discusses the unique targets that are important during disease progression. We review recent advances in site-specific therapy using novel targeted drug-delivery and nanoparticle-carrier systems. Furthermore, we explore the limitations and future perspectives of site-specific therapy for CVDs.

Unique Angiogenesis From Cardiac Arterioles During Pericardial Adhesion Formation

Objectives

The molecular mechanisms underlying post-operative pericardial adhesions remain poorly understood. We aimed to unveil the temporal molecular and cellular mechanisms underlying tissue dynamics during adhesion formation, including inflammation, angiogenesis, and fibrosis.

Methods and Results

We visualized cell-based tissue dynamics during pericardial adhesion using histological evaluations. To determine the molecular mechanism, RNA-seq was performed. Chemical inhibitors were administered to confirm the molecular mechanism underlying adhesion formation. A high degree of adhesion formation was observed during the stages in which collagen production was promoted. Histological analyses showed that arterioles excessively sprouted from pericardial tissues after the accumulation of neutrophils on the heart surface in mice as well as humans. The combination of RNA-seq and histological analyses revealed that hyperproliferative endothelial and smooth muscle cells with dedifferentiation appeared in cytokine-exposed sprouting vessels and adhesion tissue but not in quiescent vessels in the heart. SMAD2/3 and ERK activation was observed in sprouting vessels. The simultaneous abrogation of PI3K/ERK or TGF-β/MMP9 signaling significantly decreased angiogenic sprouting, followed by inhibition of adhesion formation. Depleting MMP9-positive neutrophils shortened mice survival and decreased angiogenic sprouting and fibrosis in the adhesion. Our data suggest that TGF-β/matrix metalloproteinase-dependent tissue remodeling and PI3K/ERK signaling activation might contribute to unique angiogenesis with dedifferentiation of vascular smooth muscle cells from the contractile to the synthetic phenotype for fibrosis in the pericardial cavity.

Conclusions

Our findings provide new insights in developing prevention strategies for pericardial adhesions by targeting the recruitment of vascular cells from heart tissues.

Macrophage-Specific IGF-1 Overexpression Reduces CXCL12 Chemokine Levels and Suppresses Atherosclerotic Burden in Apoe-Deficient Mice

OBJECTIVE

IGF-1 (insulin-like growth factor 1) exerts pleiotropic effects including promotion of cellular growth, differentiation, survival, and anabolism. We have shown that systemic IGF-1 administration reduced atherosclerosis in Apoe^-/- (apolipoprotein E deficient) mice, and this effect was associated with a reduction in lesional macrophages and a decreased number of foam cells in the plaque. Almost all cell types secrete IGF-1, but the effect of macrophage-derived IGF-1 on the pathogenesis of atherosclerosis is poorly understood. We hypothesized that macrophage-derived IGF-1 will reduce atherosclerosis. Approach and Results: We created macrophage-specific IGF-1 overexpressing mice on an Apoe^-/- background. Macrophage-specific IGF-1 overexpression reduced plaque macrophages, foam cells, and atherosclerotic burden and promoted features of stable atherosclerotic plaque. Macrophage-specific IGF1 mice had a reduction in monocyte infiltration into plaque, decreased expression of CXCL12 (CXC chemokine ligand 12), and upregulation of ABCA1 (ATP-binding cassette transporter 1), a cholesterol efflux regulator, in atherosclerotic plaque and in peritoneal macrophages. IGF-1 prevented oxidized lipid-induced CXCL12 upregulation and foam cell formation in cultured THP-1 macrophages and increased lipid efflux. We also found an increase in cholesterol efflux in macrophage-specific IGF1-derived peritoneal macrophages.

CONCLUSIONS

Macrophage IGF-1 overexpression reduced atherosclerotic burden and increased features of plaque stability, likely via a reduction in CXCL12-mediated monocyte recruitment and an increase in ABCA1-dependent macrophage lipid efflux.

Niclosamide downregulates LOX-1 expression in mouse vascular smooth muscle cells and changes the composition of atherosclerotic plaques in ApoE-/- mice

Genetic lineage tracing studies have shown that phenotypic switching of vascular smooth muscle cells (VSMCs) results in less-differentiated cells, including macrophage-like cells that lack traditional VSMC markers. This switching contributes to the formation of necrotic core in plaques and promotes atherosclerosis, which is important for plaque stability. Niclosamide, a commonly used anti-helminthic drug, has recently attracted attention as an anti-cancer drug that inhibits multiple signaling pathways. The expression of the S100A4 protein is upregulated in synthetic VSMCs and inhibited by niclosamide on metastatic progression in colon cancer. We aimed to test the effect of niclosamide on VSMC phenotype switching and plaque stability. To examine murine atherosclerosis, we induced experimental lesions by blood flow cessation in apolipoprotein E knockout mice fed a high-fat diet. Oral administration of niclosamide changed 4-week-old plaques to collagen-rich and less-necrotic core phenotypes and downregulated the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in vivo. In vitro analysis indicated that niclosamide reduced LOX-1 expression in VSMCs in a concentration-dependent and S100A4-independent manner. The inhibitory effect of niclosamide on LOX-1 and collagen type I was associated with the inactivation of the nuclear factor-κB signaling pathway. We demonstrated that the administration of niclosamide reduced LOX-1 expression and altered the composition of murine carotid plaques. Our results highlight the potential of niclosamide as an atheroprotective agent that enhances atherosclerotic plaque stability.

Circular RNA circUBR4 regulates ox-LDL-induced proliferation and migration of vascular smooth muscle cells through miR-185-5p/FRS2 axis

Circular RNAs (circRNAs) have been reported to play vital roles in atherosclerosis. However, the precise roles of circUBR4 in atherosclerosis remain unclear. The purpose of this study is to investigate the regulatory roles of circUBR4 in atherosclerosis. The expression levels of circUBR4, miR-185-5p, and Fibroblast growth factor receptor substrate 2 (FRS2) were analyzed by real-time quantitative polymerase chain reaction (RT-qPCR) assay. Human vascular smooth muscle cells (VSMCs) were treated with oxidized low-density lipoprotein (ox-LDL) to mimic atherosclerosis condition in vitro. Cell proliferation was determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide (MTT), colony-forming, and 5-ethynyl-2'-deoxyuridine (EdU) assays. Wound healing and transwell assays were used to assess cell migration. The interaction relationship between miR-185-5p and circUBR4 or FRS2 was confirmed by dual-luciferase reporter and RNA pull-down assays. CircUBR4 was overexpressed in atherosclerosis patients and VSMCs treated with ox-LDL, and the knockdown of circUBR4 abolished ox-LDL-induced enhanced effects on the proliferation and migration of VSMCs. MiR-185-5p, interacted with FRS2, was a target of circUBR4 in VSMCs. The silencing of miR-185-5p reversed the effects caused by circUBR4 knockdown on ox-LDL-induced VSMCs. In addition, overexpression of miR-185-5p suppressed the proliferation and migration of VSMCs by targeting FRS2. CircUBR4 contributed to ox-LDL-induced VSMC proliferation and migration through up-regulating FRS2 via miR-185-5p.

Substrate Stiffness Regulates Cholesterol Efflux in Smooth Muscle Cells

The infiltration and deposition of cholesterol in the arterial wall play an important role in the initiation and development of atherosclerosis. Smooth muscle cells (SMCs) are the major cell type in the intima. Upon exposure to cholesterol, SMCs may undergo a phenotype switching into foam cells. Meanwhile, the pathological processes of the blood vessel such as cholesterol deposition and calcification induce the changes in the substrate stiffness around SMCs. However, whether substrate stiffness affects the cholesterol accumulation in SMCs and the formation of foam cells is not well-understood. In this study, SMCs were cultured on the substrates with different stiffnesses ranging from 1 to 100 kPa and treated with cholesterol. We found that cholesterol accumulation in SMCs was higher on 1 and 100 kPa substrates than that on intermediate stiffness at 40 kPa; consistently, total cholesterol (TC) content on 1 and 100 kPa substrates was also higher. As a result, the accumulation of cholesterol increased the expression of macrophage marker CD68 and downregulated SMC contractile marker smooth muscle α-actin (ACTA2). Furthermore, the mRNA and protein expression level of cholesterol efflux gene ATP-binding cassette transporter A1 (ABCA1) was much higher on 40 kPa substrate. With the treatment of a liver X receptor (LXR) agonist GW3965, the expression of ABCA1 increased and cholesterol loading decreased, showing an additive effect with substrate stiffness. In contrast, inhibition of LXR decreased ABCA1 gene expression and increased cholesterol accumulation in SMCs. Consistently, when ABCA1 gene was knockdown, the cholesterol accumulation was increased in SMCs on all substrates with different stiffness. These results revealed that substrate stiffness played an important role on SMCs cholesterol accumulation by regulating the ABCA1 expression. Our findings on the effects of substrate stiffness on cholesterol efflux unravel a new mechanism of biophysical regulation of cholesterol metabolism and SMC phenotype, and provide a rational basis for the development of novel therapies.

Phenotypic Modulation of Macrophages and Vascular Smooth Muscle Cells in Atherosclerosis-Nitro-Redox Interconnections

Monocytes/macrophages and vascular smooth muscle cells (vSMCs) are the main cell types implicated in atherosclerosis development, and unlike other mature cell types, both retain a remarkable plasticity. In mature vessels, differentiated vSMCs control the vascular tone and the blood pressure. In response to vascular injury and modifications of the local environment (inflammation, oxidative stress), vSMCs switch from a contractile to a secretory phenotype and also display macrophagic markers expression and a macrophagic behaviour. Endothelial dysfunction promotes adhesion to the endothelium of monocytes, which infiltrate the sub-endothelium and differentiate into macrophages. The latter become polarised into M1 (pro-inflammatory), M2 (anti-inflammatory) or Mox macrophages (oxidative stress phenotype). Both monocyte-derived macrophages and macrophage-like vSMCs are able to internalise and accumulate oxLDL, leading to formation of “foam cells” within atherosclerotic plaques. Variations in the levels of nitric oxide (NO) can affect several of the molecular pathways implicated in the described phenomena. Elucidation of the underlying mechanisms could help to identify novel specific therapeutic targets, but to date much remains to be explored. The present article is an overview of the different factors and signalling pathways implicated in plaque formation and of the effects of NO on the molecular steps of the phenotypic switch of macrophages and vSMCs.

Regulation of autophagy by controlling Erk1/2 and mTOR for platelet-derived growth factor-BB-mediated vascular smooth muscle cell phenotype shift

AIMS

Vascular smooth muscle cell (VSMC) phenotype shift is involved in the pathophysiology of vascular injury or platelet-derived growth factor (PDGF)-induced abnormal proliferation and migration of VSMCs. We aimed to investigate the underlying mechanism involved in PDGF-mediated signaling pathways and autophagy regulation followed by VSMC phenotype shift.

MAIN METHODS

The proliferation, migration and apoptosis of cultured rat aortic VSMCs were measured, and cells undergoing phenotype shift and autophagy were examined. Specific inhibitors for target proteins in signaling pathways were applied to clarify their roles in regulating cell functions.

KEY FINDINGS

PDGF-BB stimulation initiated autophagy activation and synthetic phenotype transition by decreasing α-smooth muscle-actin (SMA), calponin and myosin heavy chain (MHC) and increasing osteopontin (OPN) expression. However, U0126, a potent extracellular signal-regulated kinase 1/2 (Erk1/2) inhibitor, decreased PDGF-BB-induced LC3 expression, while rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), increased it. Furthermore, U0126 decreased the expresseion of autophagy-related genes (Atgs) such as beclin-1, Atg7, Atg5, and Atg12-Atg5 complex, indicating that Erk1/2 is a regulator of PDGF-BB-induced VSMC autophagy. Regardless of autophagy inhibition by U0126 or activation by rapamycin, the PDGF-BB-induced decrease in SMA, calponin and MHC and increase in OPN expression were inhibited. Furthermore, PDGF-BB-stimulated VSMC proliferation, migration and proliferating cell nuclear antigen (PCNA) expression were inhibited by U0126 and rapamycin.

SIGNIFICANCE

These findings suggest that PDGF-BB-induced autophagy is strongly regulated by Erk1/2, an mTOR-independent pathway, and any approach for targeting autophagy modulation is a potential therapeutic strategy for addressing abnormal VSMC proliferation and migration.

MiR-155 acts as an inhibitory factor in atherosclerosis-associated arterial pathogenesis by down-regulating NoxA1 related signaling pathway in ApoE-/- mouse

Background

To investigate the protective efficacy of miR-155 on down regulating NADPH oxidase isoform subunit A1 (NoxA1) gene expression, resulting in inhibition of VSMC migration and over proliferation and thus ameliorating the progression of arterial atherosclerosis in AS mouse model. Therefore, to further explore the regulatory effect of miR-155 on neointima formation in AS and locate potential anti-atherosclerosis target.

Methods

The mouse vascular aorta smooth muscle cell (MOVAS) was cultured and transfected with recombinant Pad2YFG adenovirus fluorescent vector with miR-155 fragment into 4 groups. Western blotting and RT-PCR were performed to identify the expression of NoxA1 under different circumstances. Fluorescence microscope was applied to observe the transfection rate of miR-155 into adenovirus. Twelve-week fatty food induced atherosclerotic ApoE^-/- mouse model was established as host to accept miR-155 transfected adenovirus transplantation to observe its effect on VSMC in AS progression. Carotid and thoracic artery were extracted at 1 month after dosing. Distribution of miR-155 was quantified via expression levels of protein and RNA to detect NoxA1, Nox1, p47phox and NADPH expression. Immunohistochemistry, fluorescence imaging and other methods were performed in arteries section to compare the thickness of neointima and assess the severity of AS in each group.

Results

Luciferase reporter gene assay showed significant expression of miR-155 in mimic group indicating that miR-155 had target binding effect with NoxA1 gene. Western blotting and RT-PCR results both showed significantly decreased NoxA1 expression in miR-155 mimic group while increased with its inhibitor. The miR-155 distribution was observed varied at 1 month after in control, miR-155 mimic and inhibitor groups. The NoxA1, NADPH, Nox1 and pp47phox protein expression in VSMC was decreased in mimic group vs control and inhibitor groups (P<0.05); no significant difference of NADPH expression was observed in all groups. The NoxA1, Nox1 and p47phox gene expression in VSMC were both found reduced compared with those of control group at week 4 (P<0.05). Immunohistochemistry staining of artery frozen sections figured out that the thickness of neointima of carotid artery in miR-155 mimic group was significantly lower vs control and inhibitor groups (P<0.01) at week 4.

Conclusions

miR-155 played an important role in NoxA1-related signaling pathway. miR-155 transfection into VSMC may have anti-inflammatory regulatory effect on NoxA1 expression in vivo and resulting in amelioration of atherosclerotic lesion in AS mouse model. In summary, miR-155 specifically plays in a negative feedback loop and demonstrates a protective role during atherosclerosis-associated VSMC proliferation and neointima formation through the miR-155-NoxA1-p47phox complex signaling pathway.

Role of Macrophages and RhoA Pathway in Atherosclerosis

The development, progression, or stabilization of the atherosclerotic plaque depends on the pro-inflammatory and anti-inflammatory macrophages. The influx of the macrophages and the regulation of macrophage phenotype, inflammatory or anti-inflammatory, are controlled by the small GTPase RhoA and its downstream effectors. Therefore, macrophages and the components of the RhoA pathway are attractive targets for anti-atherosclerotic therapies, which would inhibit macrophage influx and inflammatory phenotype, maintain an anti-inflammatory environment, and promote tissue remodeling and repair. Here, we discuss the recent findings on the role of macrophages and RhoA pathway in the atherosclerotic plaque formation and resolution and the novel therapeutic approaches.

Extreme Diversity of the Human Vascular Mesenchymal Cell Landscape

Background Human mesenchymal cells are culprit factors in vascular (patho)physiology and are hallmarked by phenotypic and functional heterogeneity. At present, they are subdivided by classic umbrella terms, such as "fibroblasts," "myofibroblasts," "smooth muscle cells," "fibrocytes," "mesangial cells," and "pericytes." However, a discriminative marker-based subclassification has to date not been established. Methods and Results As a first effort toward a classification scheme, a systematic literature search was performed to identify the most commonly used phenotypical and functional protein markers for characterizing and classifying vascular mesenchymal cell subpopulation(s). We next applied immunohistochemistry and immunofluorescence to inventory the expression pattern of identified markers on human aorta specimens representing early, intermediate, and end stages of human atherosclerotic disease. Included markers comprise markers for mesenchymal lineage (vimentin, FSP-1 [fibroblast-specific protein-1]/S100A4, cluster of differentiation (CD) 90/thymocyte differentiation antigen 1, and FAP [fibroblast activation protein]), contractile/non-contractile phenotype (α-smooth muscle actin, smooth muscle myosin heavy chain, and nonmuscle myosin heavy chain), and auxiliary contractile markers (h1-Calponin, h-Caldesmon, Desmin, SM22α [smooth muscle protein 22α], non-muscle myosin heavy chain, smooth muscle myosin heavy chain, Smoothelin-B, α-Tropomyosin, and Telokin) or adhesion proteins (Paxillin and Vinculin). Vimentin classified as the most inclusive lineage marker. Subset markers did not separate along classic lines of smooth muscle cell, myofibroblast, or fibroblast, but showed clear temporal and spatial diversity. Strong indications were found for presence of stem cells/Endothelial-to-Mesenchymal cell Transition and fibrocytes in specific aspects of the human atherosclerotic process. Conclusions This systematic evaluation shows a highly diverse and dynamic landscape for the human vascular mesenchymal cell population that is not captured by the classic nomenclature. Our observations stress the need for a consensus multiparameter subclass designation along the lines of the cluster of differentiation classification for leucocytes.

Role of Vascular Smooth Muscle Cell Plasticity and Interactions in Vessel Wall Inflammation

The pathobiology of atherosclerotic disease requires further elucidation to discover new approaches to address its high morbidity and mortality. To date, over 17 million cardiovascular-related deaths have been reported annually, despite a multitude of surgical and nonsurgical interventions and advances in medical therapy. Existing strategies to prevent disease progression mainly focus on management of risk factors, such as hypercholesterolemia. Even with optimum current medical therapy, recurrent cardiovascular events are not uncommon in patients with atherosclerosis, and their incidence can reach 10–15% per year. Although treatments targeting inflammation are under investigation and continue to evolve, clinical breakthroughs are possible only if we deepen our understanding of vessel wall pathobiology. Vascular smooth muscle cells (VSMCs) are one of the most abundant cells in vessel walls and have emerged as key players in disease progression. New technologies, including in situ hybridization proximity ligation assays, in vivo cell fate tracing with the CreER^T2-loxP system and single-cell sequencing technology with spatial resolution, broaden our understanding of the complex biology of these intriguing cells. Our knowledge of contractile and synthetic VSMC phenotype switching has expanded to include macrophage-like and even osteoblast-like VSMC phenotypes. An increasing body of data suggests that VSMCs have remarkable plasticity and play a key role in cell-to-cell crosstalk with endothelial cells and immune cells during the complex process of inflammation. These are cells that sense, interact with and influence the behavior of other cellular components of the vessel wall. It is now more obvious that VSMC plasticity and the ability to perform nonprofessional phagocytic functions are key phenomena maintaining the inflammatory state and senescent condition and actively interacting with different immune competent cells.

Regulatory Roles of Related Long Non-coding RNAs in the Process of Atherosclerosis

Atherosclerosis (AS) is the main cause of coronary heart disease, cerebral infarction, and peripheral vascular disease, which comprise serious hazards to human health. Atherosclerosis is characterized by the deposition of lipids on the interior walls of blood vessels, causing an inflammatory response of immune cells, endothelial cells, and smooth muscle cells, and a proliferation cascade reaction. Despite years of research, the underlying pathogenesis of AS is not fully defined. Recent advances in our understanding of the molecular mechanisms by which non-coding RNA influences the initiation and progression of AS have shown that long non-coding RNAs (lncRNAs) regulate important stages in the atherosclerotic process. In this review, we summarize current knowledge of lncRNAs, which influence the development of AS. We review the regulatory processes of lncRNAs on core stages of atherosclerotic progression, including lipid metabolism, inflammation, vascular cell proliferation, apoptosis, adhesion and migration, and angiogenesis. A growing body of evidence suggests that lncRNAs have great potential as new therapeutic targets for the treatment of vascular diseases.

TL1A inhibits atherosclerosis in apoE-deficient mice by regulating the phenotype of vascular smooth muscle cells

TNF ligand-related molecule 1A (TL1A) is a vascular endothelial growth inhibitor to reduce neovascularization. Lack of apoE a expression results in hypercholesterolemia and atherosclerosis. In this study, we determined the precise effects of TL1A on the development of atherosclerosis and the underlying mechanisms in apoE-deficient mice. After 12 weeks of pro-atherogenic high-fat diet feeding and TL1A treatment, mouse aorta, serum, and liver samples were collected and used to assess atherosclerotic lesions, fatty liver, and expression of related molecules. We found that TL1A treatment significantly reduced lesions and enhanced plaque stability. Mechanistically, TL1A inhibited formation of foam cells derived from vascular smooth muscle cells (VSMCs) but not macrophages by activating expression of ABC transporter A1 (ABCA1), ABCG1, and cholesterol efflux in a liver X receptor-dependent manner. TL1A reduced the transformation of VSMCs from contractile phenotype into synthetic phenotypes by activating expression of contractile marker α smooth muscle actin and inhibiting expression of synthetic marker osteopontin, or osteoblast-like phenotype by reducing calcification. In addition, TL1A ameliorated high-fat diet-induced lipid metabolic disorders in the liver. Taken together, our work shows that TL1A can inhibit the development of atherosclerosis by regulating VSMC/foam cell formation and switch of VSMC phenotypes and suggests further investigation of its potential for atherosclerosis treatment.

Calcium-Binding Protein S100A4 Is Upregulated in Carotid Atherosclerotic Plaques and Contributes to Expansive Remodeling

Background

Carotid plaques with expansive arterial remodeling are closely related to cerebral ischemic events. Although S100A4 (S100 calcium‐binding protein A4) is expressed in atherosclerotic lesions, its role in atherosclerotic plaque progression remains unknown. In this study, we examined the association between carotid arterial expansive remodeling and S100A4 expression.

Methods and Results

Preoperative high‐resolution magnetic resonance imaging was used to assess luminal stenosis and vascular remodeling in patients undergoing carotid endarterectomy. To examine murine carotid atherosclerosis, we induced experimental lesions by flow cessation in apolipoprotein E‐deficient mice fed a high‐fat diet. The role of S100A4 in plaque formation and smooth muscle cell proliferation was investigated in vivo and in vitro, respectively. Human carotid arterial expansive remodeling showed positive correlations with the expression of S100A4, MMP2, and MMP9. S100A4 mRNA levels were positively correlated with those of MMP2, MMP9, and MMP13. S100A4 was expressed in vascular smooth muscle cells (VSMCs) and VSMC‐derived foam cells in the plaque shoulder and marginal areas. S100A4 expression increased concomitantly with plaque formation in our animal model. Exogenous recombinant S100A4 protein enhanced the levels of Mmp2, Mmp9, and Mmp13 and the cell proliferation ability in VSMCs. A chemotaxis assay indicated that extracellular S100A4 functions as a chemoattractant for VSMCs.

Conclusions

S100A4 expression was elevated in human carotid plaques and showed a positive correlation with the degree of expansive remodeling. S100A4‐positive VSMC‐derived cells are considered to play an important role in carotid expansive remodeling.

Deletion or Inhibition of NOD1 Favors Plaque Stability and Attenuates Atherothrombosis in Advanced Atherogenesis †

Atherothrombosis, the main cause of acute coronary syndromes (ACS), is characterized by the rupture of the atherosclerotic plaque followed by the formation of thrombi. Fatal plaque rupture sites show large necrotic cores combined with high levels of inflammation and thin layers of collagen. Plaque necrosis due to the death of macrophages and smooth muscle cells (SMCs) remains critical in the process. To determine the contribution of the innate immunity receptor NOD1 to the stability of atherosclerotic plaque, Apoe^-/- and Apoe^-/- Nod1^-/- atherosclerosis prone mice were placed on a high-fat diet for 16 weeks to assess post-mortem advanced atherosclerosis in the aortic sinus. The proliferation and apoptosis activity were analyzed, as well as the foam cell formation capacity in these lesions and in primary cultures of macrophages and vascular SMCs obtained from both groups of mice. Our results reinforce the preeminent role for NOD1 in human atherosclerosis. Advanced plaque analysis in the Apoe^-/- atherosclerosis model suggests that NOD1 deficiency may decrease the risk of atherothrombosis by decreasing leukocyte infiltration and reducing macrophage apoptosis. Furthermore, Nod1^-/- SMCs exhibit higher proliferation rates and decreased apoptotic activity, contributing to thicker fibrous caps with reduced content of pro-thrombotic collagen. These findings demonstrate a direct link between NOD1 and plaque vulnerability through effects on both macrophages and SMCs, suggesting promising insights for early detection of biomarkers for treating patients before ACS occurs.

The role of sialic acids in the initiation of atherosclerosis

Atherosclerosis is a major cause of disease-related mortality around the globe. The main characteristic of the disease is an accumulation of plaque on the arterial wall and subsequent erosion or rupture of some plaques. Atherosclerosis often leads to cardiovascular disease and such acute complications as myocardial infarction or ischemic stroke due to thrombus formation. Most recent advances in atherosclerotic research state that the modifications of low-density lipoprotein (LDL) are one of the most significant stages in the disease initiation, and among these modifications desialylation is of particular interest. Sialic acids are widely expressed on all types of cells of many organisms and participate in numerous biological processes. Regarding atherosclerosis, sialidases that are responsible for the regulation of the sialic component of different molecules, are probably one of the most crucial enzymatic families. Sufficient sialylation of vascular endothelium defines its susceptibility to an atherogenic plaque formation. Moreover, the desialylation of LDL provokes an accumulation of cholesterol and lipids in the arterial walls. According to the multiple involvements of sialic acids and related enzymes, sialidases, in the initiation and development of atherosclerosis, the deeper understanding of their exact role, as well as cellular and molecular mechanisms, will allow creating more targeted and effective therapeutic and diagnostic approaches.

Lipotoxicity and Diabetic Nephropathy: Novel Mechanistic Insights and Therapeutic Opportunities

Lipotoxicity is characterized by the ectopic accumulation of lipids in organs different from adipose tissue. Lipotoxicity is mainly associated with dysfunctional signaling and insulin resistance response in non-adipose tissue such as myocardium, pancreas, skeletal muscle, liver, and kidney. Serum lipid abnormalities and renal ectopic lipid accumulation have been associated with the development of kidney diseases, in particular diabetic nephropathy. Chronic hyperinsulinemia, often seen in type 2 diabetes, plays a crucial role in blood and liver lipid metabolism abnormalities, thus resulting in increased non-esterified fatty acids (NEFA). Excessive lipid accumulation alters cellular homeostasis and activates lipogenic and glycogenic cell-signaling pathways. Recent evidences indicate that both quantity and quality of lipids are involved in renal damage associated to lipotoxicity by activating inflammation, oxidative stress, mitochondrial dysfunction, and cell-death. The pathological effects of lipotoxicity have been observed in renal cells, thus promoting podocyte injury, tubular damage, mesangial proliferation, endothelial activation, and formation of macrophage-derived foam cells. Therefore, this review examines the recent preclinical and clinical research about the potentially harmful effects of lipids in the kidney, metabolic markers associated with these mechanisms, major signaling pathways affected, the causes of excessive lipid accumulation, and the types of lipids involved, as well as offers a comprehensive update of therapeutic strategies targeting lipotoxicity.

Statistical analysis plan for "A randomised, controlled study to evaluate the effects of switching from cigarette smoking to using a tobacco heating product on health effect indicators in healthy subjects"

Tobacco harm reduction strategies aim to substitute smoking with potentially reduced risk products (PRRPs) such as e-cigarettes and tobacco-heating products (THPs). The health benefits of switching from smoking to PRRPs is unknown. A randomised controlled trial is being conducted to increase understanding of the health effects of switching from smoking to a THP in a 12-month long ambulatory study (ISRCTN81075760). Here we describe the study endpoints and the statistical analysis plan. Endpoints are divided into biomarkers of exposure (BoE) to tobacco smoke constituents and health effect indicators related to risk of lung cancer, cardiovascular and obstructive lung disease. These have been selected on the basis of extensive literature evidence. Three primary endpoints, augmentation index (risk factor for cardiovascular disease), total NNAL (linked to lung cancer) and 8-Epi-PGF2α type III (indicator of oxidative stress linked to various diseases), and multiple secondary endpoints will be analysed at 90, 180, and 360 days. Changes from baseline will be compared between study arms by specific contrasts in mixed models. Study wise multiple comparisons adjustments will be performed to account for multiplicity of timepoints and comparisons within timepoints. Generalisability of outcomes will be tested by a sensitivity analysis adjusting for age and gender. Importantly, an ancillary analysis will be performed to assess product compliance during the study based on plasma levels of CEVal, a surrogate marker for acrylonitrile exposure. The rationale underlying the selection of BoEs and health effect indicators, coupled with the statistical analysis plan will be central to understanding the potential health effects of replacing smoking with THP use for one year.

Autophagy as an emerging therapeutic target for age-related vascular pathologies

Introduction: The incidence of age-related vascular diseases such as arterial stiffness, hypertension and atherosclerosis, is rising dramatically and is substantially impacting healthcare systems. Mounting evidence suggests that there is an important role for autophagy in maintaining (cardio)vascular health. Impaired vascular autophagy has been linked to arterial aging and the initiation of vascular disease.Areas covered: The function and implications of autophagy in vascular smooth muscle cells and endothelial cells are discussed in healthy blood vessels and arterial disease. Furthermore, we discuss current treatment options for vascular disease and their links with autophagy. A literature search was conducted in PubMed up to October 2019.Expert opinion: Although the therapeutic potential of inducing autophagy in age-related vascular pathologies is considerable, several issues should be addressed before autophagy induction can be clinically used to treat vascular disease. These issues include uncertainty regarding the most effective drug target as well as the lack of potency and selectivity of autophagy inducing drugs. Moreover, drug tolerance or autophagy mediated cell death have been reported as possible adverse effects. Special attention is required for determining the cause of autophagy deficiency to optimize the treatment strategy.

Immune and Smooth Muscle Cells Interactions in Atherosclerosis: How to Target a Breaking Bad Dialogue?

Inflammation is a well-known pathophysiological factor of atherosclerosis but its therapeutic targeting has long been ignored. However, recent advances in the understanding of the immune mechanisms implicated in atherosclerosis have unveiled several therapeutic targets currently undergoing clinical trials. These studies have also shed light on a dialogue between the immune compartment and vascular smooth muscle cells (VSMCs) that plays a critical role in atherosclerotic disease initiation, progression, and stabilization. Our review focuses on the link between cellular and soluble immune effectors and VSMC behavior at different phases of the pathology. Furthermore, we discuss the potential targeting of these interactions to efficiently prevent cardiovascular diseases.

Takayasu Arteritis with Dyslipidemia Increases Risk of Aneurysm

Low-density lipoprotein cholesterol (LDL-C) has been associated with the occurrence of abdominal aortic aneurysm. However, whether LDL-C elevation associated with aneurysms in large vessel vasculitis is unknown. The aim of this study is to investigate the clinical and laboratory features of Takayasu arteritis (TAK) and explore the risk factors that associated with aneurysm in these patients. This retrospective study compared the clinical manifestations, laboratory parameters, and imaging results of 103 TAK patients with or without aneurysms and analyzed the risk factors of aneurysm formation. 20.4% of TAK patients were found to have aneurysms. The LDL-C levels was higher in the aneurysm group than in the non-aneurysm group (2.9 ± 0.9 mmol/l vs. 2.4 ± 0.9 mmol/l, p = 0.032). Elevated serum LDL-C levels increased the risk of aneurysm by 5.8-fold (p = 0.021, odds ratio [OR] = 5.767, 95% confidence interval [CI]: 1.302-25.543), and the cutoff value of level of serum LDL-C was 3.08 mmol/l. The risk of aneurysm was 4.2-fold higher in patients with disease duration >5 years (p = 0.042, OR = 4.237, 95% CI: 1.055-17.023), and 2.9-fold higher when an elevated erythrocyte sedimentation rate was present (p = 0.077, OR = 2.851, 95% CI: 0.891-9.115). In this study, elevated LDL-C levels increased the risk of developing aneurysms in patients with TAK.

Elevated Neuropeptide Y in Endothelial Dysfunction Promotes Macrophage Infiltration and Smooth Muscle Foam Cell Formation

Endothelial dysfunction has been linked to vascular inflammation and foam cell formation but the underlying mechanisms still remain unclear. We sought to define the factors inducing inflammation and smooth muscle foam cell formation under endothelial dysfunction using endothelial nitric oxide synthase (eNOS)-deficient mice. Vascular smooth muscle cells (VSMCs) from eNOS-deficient mice displayed increased expression of macrophage-related genes and elevated lipid uptake. Neuropeptide Y (NPY) was upregulated in the aorta from the eNOS-deficient mice and promoted macrophage chemotaxis toward VSMCs while enhancing the activity of matrix metalloproteinase-3. Notably, NPY induced lipid uptake in VSMCs, facilitating smooth muscle foam cell formation, in association with enhanced expression of genes related to modified low-density lipoprotein uptake and macrophages. NPY was augmented by inflammatory pentraxin 3 (PTX3) in VSMCs. PTX3 enhanced macrophage migratory capacity through the NPY/neuropeptide Y receptor axis and this effect was attenuated by pharmacological inhibition with a receptor-specific antagonist. These observations suggest that endothelial dysfunction leads to the elevation of NPY that amplifies vascular inflammation by increasing inflammatory cell chemotaxis and triggers smooth muscle foam cell formation.

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

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

Celastrol-loaded PEG-b-PPS nanocarriers as an anti-inflammatory treatment for atherosclerosis

In this work, the hydrophobic small molecule NF-κB inhibitor celastrol was loaded into poly(ethylene glycol)-b-poly(propylene sulfide) (PEG-b-PPS) micelles. PEG-b-PPS micelles demonstrated high loading efficiency, low polydispersity, and no morphological changes upon loading with celastrol. Encapsulation of celastrol within these nanocarriers significantly reduced cytotoxicity compared to free celastrol, while simultaneously expanding the lower concentration range for effective inhibition of NF-κB signaling by nearly 50 000-fold. Furthermore, celastrol-loaded micelles successfully reduced TNF-α secretion after LPS stimulation of RAW 264.7 cells and reduced the number of neutrophils and inflammatory monocytes within atherosclerotic plaques of ldlr-/- mice. This reduction in inflammatory cells was matched by a reduction in plaque area, suggesting that celastrol-loaded nanocarriers may serve as an anti-inflammatory treatment for atherosclerosis.

Paeonol: pharmacological effects and mechanisms of action

Paeonia suffruticosa possesses various medicinal benefits and has been used extensively in traditional oriental medicine for thousands of years. Paeonol is the main component isolated from the root bark of Paeonia suffruticosa. The pharmacological effects of Paeonia suffruticosa are mostly attributed to paeonol. Paeonol injection has been successfully applied in China for nearly 50 years for inflammation/pain-related indications. Currently, the dosage forms of paeonol approved by China Food and Drug Administration include tablet, injection, and external preparations such as ointment and adhesive plaster. So far, the clinical applications of paeonol are mainly focusing on the anti-inflammatory activity. Studies of other pharmacological activities of paeonol are developing rapidly, and which may play an important role in the future. Besides, substantial mechanisms of pharmacological action of paeonol have been clarified in recent years. In this review, we summarize the pharmacological effects anti-inflammatory, neuroprotective, anti-tumor, anti-cardiovascular diseases and associated mechanisms of action of paeonol up to date.

miR-185 silencing promotes the progression of atherosclerosis via targeting stromal interaction molecule 1

BACKGROUND

Atherosclerosis (AS) is a major risk factor for cardiovascular disease. microRNAs play a key role in gene regulation in the formation and development of atherosclerotic plaques. Herein, the role and target gene of miR-185 in AS were explored.

MATERIALS AND METHODS

Cell viability, migration and invasion were examined by cell counting kit-8 (CCK-8) and transwell assay. The relative luciferase activity was measured by luciferase reporter assay. The levels of miR-185, STIM1, vascular endothelial growth factor (VEGF) and matrix metalloprotein-9 (MMP-9) were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot.

RESULTS

The results revealed that ox-LDL decreased miR-185 expression, and enhanced STIM1 expression in MOVAS cells, as well promoted cell viability, migration and invasion. 3'-UTR of STIM1 contained miR-185 binding site according to the Targetscan. miR-185 silencing or STIM1 overexpression promoted the viability, migration and invasion of ox-LDL-induced MOVAS cells. miR-185 overexpression or STIM1 silencing had the opposite effect. Besides, miR-185 silencing up-regulated the levels of VEGF and MMP-9 in vitro, and increased the lesions of arterial wall tissues and STIM1 positive rate in vivo. However, STIM1 silencing reversed these effects.

CONCLUSIONS

Sum up, STIM1 was a potential target gene of miR-185 in AS. Knockdown of miR-185 facilitated the progression of AS through enhancing cell proliferation, migration and invasion via targeting STIM1. The research provides a novel view of miR-185/STIM1 axis function in AS development, and this targeting method may prevent and treat AS.

Sudden coronary death in the young: Evidence of contractile phenotype of smooth muscle cells in the culprit atherosclerotic plaque

BACKGROUND

Culprit coronary atherosclerotic plaques (APs) from young sudden cardiac death (SCD) victims are mostly non-atheromatous, i.e., consisting of proliferative smooth muscle cells (SMCs). Coronary vasospasm has been advocated to explain plaque instability in the absence of thrombosis. Our aim was to characterize the SMC phenotype in the intima and media of coronary arteries from young SCD victims.

METHODS AND RESULTS

A total of 38 coronary artery segments were studied: (a) 18 APs from young (≤40 years old) SCD patients, (b) 9 APs from old (>40 years old) SCD patients, (c) 11 non-atherosclerotic coronary arteries from young patients (≤40 years old). Markers of differentiated SMCs such as α-smooth muscle actin (α-SMA), smooth muscle myosin heavy chains (SMMHCs), and heavy-caldesmon (h-CaD), were assessed in intima and media by immunohistochemistry and quantified morphometrically. In the intima, their expression was higher in non-atherosclerotic arteries (44.37 ± 3.03% for α-SMA, 14.21 ± 2.01% for SMMHCs, 8.90 ± 1.33% for h-CaD) and APs from young SCD victims (38.95 ± 2.29% for α-SMA, 11.92 ± 1.92% for SMMHCs, 8.93 ± 1.12% for h-CaD) compared with old patients (22.01 ± 3.56% for α-SMA, 6.39 ± 0.7% for SMMHCs, 3.00 ± 0.57% for h-CaD; all P statistically significant). The media of non-atherosclerotic arteries and APs from young SCD victims exhibited strong positivity for the differentiation markers unlike that of old patients.

CONCLUSIONS

SMCs of coronary APs as well as from the underlying media from young SCD victims exhibit strong contractile phenotype. In the setting of critical stenosis, both intima and media SMC contractility might contribute to transient coronary spasm leading to myocardial ischemia and SCD.

Pro‑atherogenic activation of A7r5 cells induced by the oxLDL/β2GPI/anti‑β2GPI complex

A previous study has revealed that oxidized low‑density lipoprotein (oxLDL)/β2‑glycoprotein I (β2GPI)/anti‑β2‑glycoprotein I (anti‑β2GPI), an immune complex, is able to activate the Toll‑like receptor 4 (TLR4)/nuclear factor κβ (NF‑κβ) inflammatory signaling pathway in macrophages, and consequently enhance foam cell formation and the secretion of prothrombin activators. However, the effects of the oxLDL/β2GPI/anti‑β2GPI complex on vascular smooth muscle cells have yet to be investigated. The present study investigated whether the oxLDL/β2GPI/anti‑β2GPI complex was able to reinforce the pro‑atherogenic activities of a rat thoracic aorta smooth muscle cell line (A7r5) and examined the underlying molecular mechanisms. The results revealed that the oxLDL/β2GPI/anti‑β2GPI complex treatment significantly (P<0.05 vs. the media, oxLDL, oxLDL/β2GPI and β2GPI/anti‑β2GPI groups) enhanced the pro‑atherogenic activation of A7r5 cells, including intracellular lipid loading, Acyl‑coenzyme A cholesterol acyltransferase mRNA expression, migration, matrix metalloproteinase‑9 and monocyte chemoattractant protein 1 secretion, all via TLR4. In addition, the expression of TLR4 and the phosphorylation of NF‑κβ p65, p38 and ERK1/2 were also upregulated in oxLDL/β2GPI/anti‑β2GPI complex‑treated A7r5 cells. Pre‑treatment with TAK‑242, a TLR4 inhibitor, was able to partly attenuate the oxLDL/β2GPI/anti‑β2GPI complex‑induced phosphorylation of NF‑κβ p65; however, it had no effect on the phosphorylation of extracellular regulated kinase 1/2 (ERK1/2) and p38. Meanwhile, the NF‑κβ p65 inhibitor ammonium pyrrolidinedithiocarbamate and the ERK1/2 inhibitor U0126, but not the p38 inhibitor SB203580, were able to block oxLDL/β2GPI/anti‑β2GPI complex‑induced foam cell formation and migration in A7r5 cells. Hence, it was demonstrated that the oxLDL/β2GPI/anti‑β2GPI complex is able to enhance the lipid uptake, migration and active molecule secretion of A7r5 cells via TLR4, and finally deteriorate atherosclerosis plaques. Additionally, it was demonstrated that oxLDL/β2GPI/anti‑β2GPI complex‑induced foam cell formation and migration may be partly mediated by the TLR4/NF‑κβ signaling pathway and that ERK1/2 may also participate in the process.

The CD44-HA axis and inflammation in atherosclerosis: A temporal perspective

Cardiovascular disease (CVD) due to atherosclerosis is a disease of chronic inflammation at both the systemic and the tissue level. CD44 has previously been implicated in atherosclerosis in both humans and mice. This multi-faceted receptor plays a critical part in the inflammatory response during the onset of CVD, though little is known of CD44's role during the latter stages of the disease. This review focuses on the role of CD44-dependent HA-dependent effects on inflammatory cells in several key processes, from disease initiation throughout the progression of atherosclerosis. Understanding how CD44 and HA regulate inflammation in atherogenesis is key in determining the utility of the CD44-HA axis as a therapeutic target to halt disease and potentially promote disease regression.

Inhibition of miR-155 attenuates abdominal aortic aneurysm in mice by regulating macrophage-mediated inflammation

The aim of the present study was to identify abdominal aortic aneurysms (AAA)-associated miR-155 contributing to AAA pathology by regulating macrophage-mediated inflammation. Angiotensin II (AngII)-infused apolipoprotein E-deficient (ApoE-/-) mice and THP-1 cells model of miR-155 overexpression and deficiency were used in the experiments. The expression of miR-155 was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cytokines were evaluated using enzyme-linked immunoabsorbent assay (ELISA). Western blotting was used to measure the levels of MMP-2, MMP-9, iNOS, and monocyte chemoattractant protein (MCP)-1 proteins. Immunostaining and transwell were used to determine CD68, elastic collagen, proliferation, and migration of vascular smooth muscle cells (VSMCs). The results showed that miR-155 and cytokines were up-regulated in AAA patients or ApoE-/- mice. Overexpression of miR-155 enhanced MMP-2, MMP-9, iNOS, and MCP-1 levels, and stimulated the proliferation and migration of VSMCs. Meanwhile, inhibition of miR-155 had the opposite effect. In addition, histology demonstrated accumulation of CD68 and elastic collagen-positive areas significantly decreased in miR-155 antagomir injection group. In conclusion, the results of the present study suggest that inhibiting miR-155 is crucial to prevent the development of AAA by regulating macrophage inflammation.

Characterization of Carotid Smooth Muscle Cells during Phenotypic Transition

Vascular smooth muscle cells (VSMCs) are central players in carotid atherosclerosis plaque development. Although the precise mechanisms involved in plaque destabilization are not completely understood, it is known that VSMC proliferation and migration participate in plaque stabilization. In this study, we analyzed expression patterns of genes involved in carotid atherosclerosis development (e.g., transcription factors of regulation of SMC genes) of VSMCs located inside or outside the plaque lesion that may give clues about changes in phenotypic plasticity during atherosclerosis. VSMCs were isolated from 39 carotid plaques extracted from symptomatic and asymptomatic patients by endarterectomy. Specific biomarker expression, related with VSMC phenotype, was analyzed by qPCR, western immunoblot, and confocal microscopy. MYH11, CNN1, SRF, MKL2, and CALD1 were significantly underexpressed in VSMCs from plaques compared with VSMCs from a macroscopically intact (MIT) region, while SPP1, KLF4, MAPLC3B, CD68, and LGALS3 were found significantly upregulated in plaque VSMCs versus MIT VSMCs. The gene expression pattern of arterial VSMCs from a healthy donor treated with 7-ketocholesterol showed high similarity with the expression pattern of carotid plaque VSMCs. Our results indicate that VSMCs isolated from plaque show a typical SMC dedifferentiated phenotype with macrophage-like features compared with VSMCs isolated from a MIT region of the carotid artery. Additionally, MYH11, KLF5, and SPP1 expression patterns were found to be associated with symptomatology of human carotid atherosclerosis.

Inflammation in human carotid atheroma plaques

Inflammation in carotid atherosclerotic plaque is linked to plaque rupture and cerebrovascular accidents. The balance between pro- and anti-inflammatory mediators governs development of the plaque, and may mediate enhancement of lesion broadening or, on the contrary, delay progression. In addition to macrophages and endothelial cells, smooth muscle cells (SMCs), which are the dominant cell subset in advanced plaques, are crucial players in carotid atherosclerosis development given their ability to differentiate into distinct phenotypes in reponse to specific signals received from the environment of the lesion. Carotid atheroma SMCs actively contribute to the inflammation in the lesion because of their acquired capacity to produce inflammatory mediators. We review the successive stages of carotid atheroma plaque formation via fatty streak early-stage toward more advanced rupture-prone lesions and document involvement of cytokines and chemokines and their cellular sources and targets in plaque progression and rupture.

ABCA1 and HDL3 are required to modulate smooth muscle cells phenotypic switch after cholesterol loading

BACKGROUND AND AIMS

Cholesterol-loaded smooth muscle cells (SMCs) modify their phenotypic behavior becoming foam cells. To characterize the role of ABCA1 and HDL3 in this process, we evaluated HDL3 effects on cholesterol-induced phenotypic changes in SMCs expressing or not ABCA1.

METHODS

SMCs, isolated from the aortae of wild-type (WT) and Abca1 knock-out (KO) mice, were cholesterol-loaded using a "water-soluble cholesterol''.

RESULTS

Cholesterol loading downregulates the expression of Acta2 and calponin (SMC markers), and increases the expression of Mac-2, CD11b and MHCII (inflammation-related genes and surface antigens) and Abca1, Abcg1. HDL3 normalizes SMC marker expression and reduces the expression of inflammation-related genes/proteins in WT cells, an effect not observed with free apoA-I. The effect of HDL3 is almost lost in Abca1 KO cells, as well as when Abca1 is silenced in WT SMC. HDL3 does not differently affect cholesterol downloading in WT or KO cells and stimulates phospholipids removal in WT cells. Similarly, the expression of myocardin and its modulators, such as miR-143/145, is reduced by cholesterol loading in WT and Abca1 KO SMCs; HDL3 normalizes their levels in WT cells but not in KO cells. On the contrary, cholesterol loading induces Klf4 expression while HDL3 restores Klf4 to basal levels in WT cells, but again this effect is not observed in KO cells.

CONCLUSIONS

Our results indicate that HDL3, by interacting with ABCA1, modulates the miR143/145-myocardin axis and prevents the cholesterol-induced gene expression modification in SMCs regardless of its cholesterol unloading capacity.

Platelet extracellular vesicles induce a pro-inflammatory smooth muscle cell phenotype

Extracellular vesicles (EVs) are mediators of cell communication during health and disease, and abundantly released by platelets upon activation or during ageing. Platelet EVs exert modulatory effects on immune and vascular cells. Platelet EVs may modulate the function of vascular smooth muscle cells (SMC). Platelet EVs were isolated from platelet-rich plasma and incubated with SMC in order to assess binding, proliferation, migration and pro-inflammatory phenotype of the cells. Platelet EVs firmly bound to resting SMC through the platelet integrin α_IIbβ₃, while binding also occurred in a CX3CL1–CX3CR1-dependent manner after cytokine stimulation. Platelet EVs increased SMC migration comparable to platelet derived growth factor or platelet factor 4 and induced SMC proliferation, which relied on CD40- and P-selectin interactions. Flow-resistant monocyte adhesion to platelet EV-treated SMC was increased compared with resting SMC. Again, this adhesion depended on integrin α_IIbβ₃ and P-selectin, and to a lesser extent on CD40 and CX3CR1. Treatment of SMC with platelet EVs induced interleukin 6 secretion. Finally, platelet EVs induced a synthetic SMC morphology and decreased calponin expression. Collectively, these data indicate that platelet EVs exert a strong immunomodulatory activity on SMC. In particular, platelet EVs induce a switch towards a pro-inflammatory phenotype, stimulating vascular remodelling.

Plaque angiogenesis and intraplaque hemorrhage in atherosclerosis

Acute cardiovascular events, due to rupture or erosion of an atherosclerotic plaque, represent the major cause of morbidity and mortality in patients. Growing evidence suggests that plaque neovascularization is an important contributor to plaque growth and instability. The vessels' immaturity, with profound structural and functional abnormalities, leads to recurrent intraplaque hemorrhage. This review discusses new insights of atherosclerotic neovascularization, including the effects of leaky neovessels on intraplaque hemorrhage, both in experimental models and humans. Furthermore, modalities for in vivo imaging and therapeutic interventions to target plaque angiogenesis will be discussed.

The phenomenon of atherosclerosis reversal and regression: Lessons from animal models

Studies in non-rodent and murine models showed that atherosclerosis can be reversed. Atherosclerosis progression induced by high-fat or cholesterol-rich diet can be reduced and reversed to plaque regression after switching to a normal diet or through administration of lipid-lowering agents. The similar process should exist in humans after implementation of lipid-lowering therapy and as a result of targeting of small rupture-prone plaques that are major contributors for acute atherosclerotic complications. Lowering of low density lipoprotein (LDL) cholesterol and the activation of reverse cholesterol transport lead to a decline in foam cell content, to the depletion of plaque lipid reservoirs, a decrease in lesional macrophage numbers through the activation of macrophage emigration and, probably, apoptosis, dampening plaque inflammation, and the induction of anti-inflammatory macrophages involved in clearance of the necrotic core and plaque healing. By contrast, plaque regression is characterized by opposite events, leading to the retention of atherogenic LDL and oxidized LDL particles in the plaque, an increased flux of monocytes, the immobilization of macrophages in the intimal vascular tissues, and the propagation of intraplaque inflammation. Transfer of various apolipoprotein (apo) genes to spontaneously hypercholesterolemic mice deficient for either apoE or LDL receptor and, especially, the implementation of the transplantation murine model allowed studying molecular mechanisms of atherosclerotic regression, associated with the depletion of atherogenic lipids in the plaque, egress of macrophages and phenotypic switch of macrophages from the proinflammatory M1 to the anti-inflammatory M2.