The role of smooth muscle cells in plaque stability: Therapeutic targeting potential

Chronic obstructive pulmonary disease and atherosclerosis: common mechanisms and novel therapeutics

Chronic obstructive pulmonary disease (COPD) and atherosclerosis are chronic irreversible diseases, that share a number of common causative factors including cigarette smoking. Atherosclerosis drastically impairs blood flow and oxygen availability to tissues, leading to life-threatening outcomes including myocardial infarction (MI) and stroke. Patients with COPD are most likely to die as a result of a cardiovascular event, with 30% of all COPD-related deaths being attributed to cardiovascular disease (CVD). Both atherosclerosis and COPD involve significant local (i.e. lung, vasculature) and systemic inflammation and oxidative stress, of which current pharmacological treatments have limited efficacy, hence the urgency for the development of novel life-saving therapeutics. Currently these diseases must be treated individually, with no therapies available that can effectively reduce the likelihood of comorbid CVD other than cessation of cigarette smoking. In this review, the important mechanisms that drive atherosclerosis and CVD in people with COPD are explained and we propose that modulation of both the oxidative stress and the inflammatory burden will provide a novel therapeutic strategy to treat both the pulmonary and systemic manifestations related to these diseases.

The Association and Pathogenesis of SERPINA3 in Coronary Artery Disease

Background: Serine proteinase inhibitor A3 (SERPINA3) has been discovered in the pathogenesis of many human diseases, but little is known about the role of SERPINA3 in coronary artery disease (CAD). Therefore, we aim to determine its relationship with CAD and its function in the pathogenesis of atherosclerosis.

Methods: In total 86 patients with CAD and 64 patients with non-CAD were compared. The plasma SERPINA3 levels were measured using ELISA. Logistic regression analysis and receiver-operating characteristic (ROC) analysis were performed to illustrate the association between plasma SERPINA3 levels and CAD. In vitro, real-time PCR (RT-PCR) and immunofluorescence staining were used to determine the expression of SERPINA3 in atherosclerotic plaques and their component cells. Then rat aortic smooth muscle cells (RASMCs) were transfected with siRNA to knock down the expression of SERPINA3 and human umbilical vein endothelial cells (HUVECs) were stimulated by SERPINA3 protein. EdU assay and scratch assay were used for assessing the capability of proliferation and migration. The cell signaling pathway was evaluated by western blot and RT-PCR.

Results: Patients with CAD [104.4(54.5–259.2) μg/mL] had higher levels of plasma SERPINA3 than non-CAD [65.3(47.5–137.3) μg/mL] (P = 0.004). After being fully adjusted, both log-transformed and tertiles of plasma SERPINA3 levels were significantly associated with CAD. While its diagnostic value was relatively low since the area under the ROC curve was 0.64 (95% CI: 0.55–0.73). Secreted SERPINA3 might increase the expression of inflammatory factors in HUVECs. Vascular smooth muscle cells had the highest SERPINA3 expression among the aorta compared to endothelial cells and inflammatory cells. The knockdown of SERPINA3 in RASMCs attenuated its proliferation and migration. The phosphorylated IκBα and its downstream pathway were inhibited when SERPINA3 was knocked down.

Conclusions: Elevated plasma SERPINA3 levels were associated with CAD. SERPINA3 can increase inflammatory factors expression in HUVECs. It can regulate VSMCs proliferation, migration, and releasing of inflammatory factors through the NF-κB signaling pathway. Thus, SERPINA3 played a significant role in the pathogenesis of atherosclerosis.

Anti-Galectin-2 antibody treatment reduces atherosclerotic plaque size and alters macrophage polarity

Background  Galectins have numerous cellular functions in immunity and inflammation. Short-term galectin-2 (Gal-2) blockade in ischemia-induced arteriogenesis shifts macrophages to an anti-inflammatory phenotype and improves perfusion. Gal-2 may also affect other macrophage-related cardiovascular diseases.

Objectives  This study aims to elucidate the effects of Gal-2 inhibition in atherosclerosis.

Methods   ApoE ^−/− mice were given a high-cholesterol diet (HCD) for 12 weeks. After 6 weeks of HCD, intermediate atherosclerotic plaques were present. To study the effects of anti-Gal-2 nanobody treatment on the progression of existing atherosclerosis, treatment with two llama-derived anti-Gal-2 nanobodies (clones 2H8 and 2C10), or vehicle was given for the remaining 6 weeks.

Results  Gal-2 inhibition reduced the progression of existing atherosclerosis. Atherosclerotic plaque area in the aortic root was decreased, especially so in mice treated with 2C10 nanobodies. This clone showed reduced atherosclerosis severity as reflected by a decrease in fibrous cap atheromas in addition to decreases in plaque size.

The number of plaque resident macrophages was unchanged; however, there was a significant increase in the fraction of CD206 ⁺ macrophages. 2C10 treatment also increased plaque α-smooth muscle content, and Gal-2 may have a role in modulating the inflammatory status of smooth muscle cells. Remarkably, both treatments reduced serum cholesterol concentrations including reductions in very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein while triglyceride concentrations were unchanged.

Conclusion  Prolonged and frequent treatment with anti-Gal-2 nanobodies reduced plaque size, slowed plaque progression, and modified the phenotype of plaque macrophages toward an anti-inflammatory profile. These results hold promise for future macrophage modulating therapeutic interventions that promote arteriogenesis and reduce atherosclerosis.

Mechanisms of vascular smooth muscle cell investment and phenotypic diversification in vascular diseases

In contrast with the heart, the adult mammalian vasculature retains significant remodelling capacity, dysregulation of which is implicated in disease development. In particular, vascular smooth muscle cells (VSMCs) play major roles in the pathological vascular remodelling characteristic of atherosclerosis, restenosis, aneurysm and pulmonary arterial hypertension. Clonal lineage tracing revealed that the VSMC-contribution to disease results from the hyperproliferation of few pre-existing medial cells and suggested that VSMC-derived cells from the same clone can adopt diverse phenotypes. Studies harnessing the powerful combination of lineage tracing and single-cell transcriptomics have delineated the substantial diversity of VSMC-derived cells in vascular lesions, which are proposed to have both beneficial and detrimental effects on disease severity. Computational analyses further suggest that the pathway from contractile VSMCs in healthy arteries to phenotypically distinct lesional cells consists of multiple, potentially regulatable, steps. A better understanding of how individual steps are controlled could reveal effective therapeutic strategies to minimise VSMC functions that drive pathology whilst maintaining or enhancing their beneficial roles. Here we review current knowledge of VSMC plasticity and highlight important questions that should be addressed to understand how specific stages of VSMC investment and phenotypic diversification are controlled. Implications for developing therapeutic strategies in pathological vascular remodelling are discussed and we explore how cutting-edge approaches could be used to elucidate the molecular mechanisms underlying VSMC regulation.

Systems toxicology study reveals reduced impact of heated tobacco product aerosol extract relative to cigarette smoke on premature aging and exacerbation effects in aged aortic cells in vitro

Aging and smoking are major risk factors for cardiovascular diseases (CVD). Our in vitro study compared, in the context of aging, the effects of the aerosol of Tobacco Heating System 2.2 (THS; an electrically heated tobacco product) and 3R4F reference cigarette smoke (CS) on processes that contribute to vascular pathomechanisms leading to CVD. Young and old human aortic smooth muscle cells (HAoSMC) were exposed to various concentrations of aqueous extracts (AE) from 3R4F CS [0.014-0.22 puffs/mL] or THS aerosol [0.11-1.76 puffs/mL] for 24 h. Key markers were measured by high-content imaging, transcriptomics profiling and multianalyte profiling. In our study, in vitro aging increased senescence, DNA damage, and inflammation and decreased proliferation in the HAoSMCs. At higher concentrations of 3R4F AE, young HAoSMCs behaved similarly to aged cells, while old HAoSMCs showed additional DNA damage and apoptosis effects. At 3R4F AE concentrations with the maximum effect, the THS AE showed no significant effect in young or old HAoSMCs. It required an approximately ten-fold higher concentration of THS AE to induce effects similar to those observed with 3R4F. These effects were independent of nicotine, which did not show a significant effect on HAoSMCs at any tested concentration. Our results show that 3R4F AE accelerates aging in young HAoSMCs and exacerbates the aging effect in old HAoSMCs in vitro, consistent with CS-related contributions to the risk of CVD. Relative to 3R4F AE, the THS AE showed a significantly reduced impact on HAoSMCs, suggesting its lower risk for vascular SMC-associated pathomechanisms leading to CVD.

Endothelial Progenitor Cells Modulate the Phenotype of Smooth Muscle Cells and Increase Their Neointimal Accumulation Following Vascular Injury

BACKGROUND

 Smooth muscle cells (SMCs) are the main driver of neointima formation and restenosis following vascular injury. In animal models, endothelial progenitor cells (EPCs) accelerate endothelial regeneration and reduce neointima formation after arterial injury; however, EPC-capture stents do not reduce target vessel failure compared with conventional stents. Here we examined the influence of EPCs on features of SMCs pivotal for their impact on injury-induced neointima formation including proliferation, migration, and phenotype switch.

METHODS AND RESULTS

 EPCs, their conditioned medium, and EPC-derived microparticles induced proliferation of SMCs while limiting their apoptosis. In transwell membrane experiments and scratch assays, EPCs stimulated migration of SMCs and accelerated their recovery from scratch-induced injury. Treatment of SMCs with an EPC-derived conditioned medium or microparticles triggered transformation of SMCs toward a synthetic phenotype. However, co-cultivation of EPCs and SMCs enabling direct cell-cell contacts preserved their original phenotype and protected from the transformative effect of SMC cholesterol loading. Adhesion of EPCs to SMCs was stimulated by SMC injury and reduced by blocking CXCR2 and CCR5. Interaction of EPCs with SMCs modulated their secretory products and synergistically increased the release of selected chemokines. Following carotid wire injury in athymic mice, injection of EPCs resulted not only in reduced neointima formation but also in altered cellular composition of the neointima with augmented accumulation of SMCs.

CONCLUSION

 EPCs stimulate proliferation and migration of SMCs and increase their neointimal accumulation following vascular injury. Furthermore, EPCs context-dependently modify the SMC phenotype with protection from the transformative effect of cholesterol when a direct cell-cell contact is established.

Mechanisms underlying the therapeutic potential of mesenchymal stem cells in atherosclerosis

Atherosclerosis is a chronic inflammatory condition resulting in the formation of fibrofatty plaques within the intimal layer of arterial walls. The identification of resident stem cells in the vascular wall has led to significant investigation into their contributions to health and disease, as well as their therapeutic potential. Of these, mesenchymal stem cells (MSCs) are the most widely studied in human clinical trials, which have demonstrated a modulatory role in vascular physiology and disease. This review highlights the most recent knowledge surrounding the cell biology of MSCs, including their origin, identification markers and differentiation potential. The limitations concerning the implementation of MSC therapy are considered and novel solutions to overcome these are proposed.

ClC-3: A Novel Promising Therapeutic Target for Atherosclerosis

Chloride channel 3 (ClC-3), a Cl^-/H⁺ antiporter, has been well established as a member of volume-regulated chloride channels (VRCCs). ClC-3 may be a crucial mediator for activating inflammation-associated signaling pathways by regulating protein phosphorylation. A growing number of studies have indicated that ClC-3 overexpression plays a crucial role in mediating increased plasma low-density lipoprotein levels, vascular endothelium dysfunction, pro-inflammatory activation of macrophages, hyper-proliferation and hyper-migration of vascular smooth muscle cells (VSMCs), as well as oxidative stress and foam cell formation, which are the main factors responsible for atherosclerotic plaque formation in the arterial wall. In the present review, we summarize the molecular structures and classical functions of ClC-3. We further discuss its emerging role in the atherosclerotic process. In conclusion, we explore the potential role of ClC-3 as a therapeutic target for atherosclerosis.

lncRNA ZFAS1 promotes the ox-LDL induced proliferation, invasion and migration of vascular smooth muscle cells

Atherosclerosis is a chronic progressive inflammatory vascular disease. The dysfunction of vascular smooth muscle cells (VSMCs) induced by oxidized low-density lipoprotein (ox-LDL) contributes to the formation of atherosclerotic lesions. Additionally, upregulation of the long non-coding RNA zinc finger antisense 1 (ZFAS1) was observed in the plaques of patients with atherosclerosis. The aim of the present study was to explore the functional role of ZFAS1 in atherosclerosis progression. Reverse transcription-quantitative PCR was performed to analyze ZFAS1 mRNA expression, and western blotting was performed to determine the protein expression levels of Ki67, proliferating cell nuclear antigen (PCNA), matrix metallopeptidase (MMP)2 and MMP9. The Cell Counting Kit-8 assay was used to test cell viability. Finally, wound healing and Transwell chamber assays were performed to evaluate cell migration and invasion, respectively. The current findings demonstrated that ZFAS1 expression was upregulated by ox-LDL stimulation in VSMCs. Moreover, ZFAS1 overexpression promoted the ox-LDL-induced proliferation, migration and invasion of VSMCs, and upregulated the expression levels of proteins associated with cellular proliferation (Ki67 and PCNA), migration and invasion (MMP2 and 9). By contrast, ZFAS1-knockdown inhibited the proliferation, migration and invasion of VSMCs, and suppressed cell proliferation-, migration- and invasion-associated protein expression. In conclusion, ZFAS1 promoted the ox-LDL-induced proliferation, invasion and migration of VSMCs. Thus, ZFAS1 may represent a novel biomarker for dysfunction of VSMCs in the pathological condition of atherosclerosis.

Sterol-resistant SCAP Overexpression in Vascular Smooth Muscle Cells Accelerates Atherosclerosis by Increasing Local Vascular Inflammation through Activation of the NLRP3 Inflammasome in Mice

Atherosclerosis is a serious age-related pathology, and one of its hallmarks is the presence of chronic inflammation. Sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP) is a cholesterol sensor that plays an essential role in regulating intracellular cholesterol homeostasis. Accordingly, dysregulation of the SCAP-SREBP pathway has been reported to be closely associated with an increased risk of obesity, hypercholesterolemia, and cardiovascular disease. In this study, we explored whether sterol-resistant SCAP (D443N mutation) in vascular smooth muscle cells (VSMCs) of mice promotes vascular inflammation and accelerates the occurrence and progression of atherosclerosis. We established a transgenic knock-in mouse model of atherosclerosis with an activating D443N mutation at the sterol-sensing domain of SCAP (SCAP^D443N) by microinjection. Next, SCAP^D443N/ApoE^-/- mice were generated by crossing SCAP^D443N mice with apolipoprotein E^-/- (ApoE^-/-) background mice. We found that sterol-resistant SCAP markedly amplified and accelerated the progression of atherosclerotic plaques in SCAP^D443N/ApoE^-/- mice compared with that in control ApoE^-/- mice. Similarly, in SCAP^D443N mice, aortic atherosclerotic plaques both appeared earlier and were greater in number than that in control SCAP^+/+ mice, both of which were fed a Western diet for 12 or 24 weeks. Moreover, we observed that sterol-resistant SCAP significantly increased local inflammation and induced endothelial dysfunction in the aortas of SCAP^D443N mice and SCAP^D443N/ApoE^-/- mice. In vitro, we also found that sterol-resistant SCAP overexpression in VSMCs increased the release of inflammatory cytokines and induced endothelial cell injury when both cell types were cocultured. Furthermore, we demonstrated that sterol-resistant SCAP overexpression in VSMCs promoted SCAP and NLRP3 inflammasome cotranslocation to the Golgi and increased the activation of the NLRP3 inflammasome pathway. These findings suggested that sterol-resistant SCAP in VSMCs of mice induced vascular inflammation and endothelial dysfunction, consequently accelerating atherosclerosis by activating the NLRP3 inflammasome pathway.

Role of vascular smooth muscle cell phenotypic switching in plaque progression: A hybrid modeling study

Growing genetic lineage mapping experiments have definitively shown a wide-ranging plasticity of vascular smooth muscle cells (VSMCs) in atherosclerotic plaque and suggested that VSMCs can modulate their phenotypes in response to plaque microenvironment. Here, a multiscale hybrid discrete-continuous (HDC) modeling system is established to investigate the complex role of VSMC phenotypic switching within atherosclerotic lesions. The cellular behaviors of VSMCs and macrophages, including proliferation, migration, phenotypic transformation and necrosis, are determined by cellular automata (CA) rules in discrete model. While the dynamics of plaque microenvironmental factors, such as lipid, extracellular matrix (ECM) and chemokines, are described by continuous reaction-diffusion equations in macroscopy. The simulation results demonstrate how the VSMC activities change the extracellular microenvironment and consequently affect the plaque morphology and stability. The regulation of VSMC phenotypes can affect not only the plaque morphology (necrotic core size and fibrous cap thickness) but also the deposition and distribution of microenvironmental factors (lipoprotein, ECM, and chemokines). In addition, it is found that plaque vulnerability can be inhibited by blocking VSMC transdifferentiation to a macrophage-like state and promoting it to a myofibroblastic phenotype, which suggests that targeting VSMC phenotypic switching could be a potential and promising therapeutic strategy for atherosclerosis.

ShenLian Extract Enhances TGF-β Functions in the Macrophage-SMC Unit and Stabilizes Atherosclerotic Plaques

Background/Aim: Macrophage polarization and phenotypic switching of smooth muscle cells (SMCs) are multi-faceted events dominating atherosclerosis (AS) progression. TGF-β was proved to been one of the bridge on the crosstalk between macrophage and SMC. ShenLian (SL) was extracted from a potent anti-atherosclerotic formula. However, its exact mechanism rebalancing inflammatory microenvironment of AS remain largely unknown. Within the entirety of macrophage and SMC, this study investigated the pharmacological effects of SL on stabilizing atherosclerotic plaques.

Methods: The main components of SL were examined by high performance liquid chromatography. Co-culture and conditioned medium models of macrophage/SMC interactions were designed to identify the relationship between macrophage polarization and switching of SMC phenotypes. Flow cytometry, immunofluorescent staining, RT-PCR, western blotting, and ELISA were used to determine the expression of molecules relating to AS progression. An atherosclerosis animal model, established by placing a perivascular collar on the right common carotid artery in ApoE^−/− mice, was used to investigate whether TGF-β is the key molecular mediator of SL in crosstalk between macrophage and SMC. Plaque size was defined by nuclear magnetic resonance imaging. Key markers related to phenotypic transformation of macrophage and SMC were determined by immunohistochemical staining.

Results: Results revealed that, accompanied by rebalanced M2 macrophage polarization, SL supported SMC phenotypic transformation and functionally reconstruct the ECM of plaques specifically in macrophage-SMC co-cultural model. Molecularly, such activity of SL closely related to the activation of STAT3/SOCS3 pathway. Furthermore, in co-culture system, up-regulation of α-SMA induced by SL could neutralized by 1D11, a TGF-β neutralizing antibody, indicating that SL mediated Macrophage-SMC communication by enhancing TGF-β. In the AS model constructed by ApoE^−/− mice, effects of SL on phenotypic transformation of macrophage and SMC has been well verified. Specific blocking of TGF-β largely attenuated the aforementioned effects of SL.

Conclusion: Our findings highlighted that TGF-β might be the responsive factor of SL within macrophage and SMC communication. This study revealed that crosstalk between macrophage and SMC forms a holistic entirety promoting atherosclerotic plaque stability.

Cell-specific epigenetic changes in atherosclerosis

Atherosclerosis is a disease of large and medium arteries that can lead to life-threatening cerebrovascular and cardiovascular consequences such as heart failure and stroke and is a major contributor to cardiovascular-related mortality worldwide. Atherosclerosis development is a complex process that involves specific structural, functional and transcriptional changes in different vascular cell populations at different stages of the disease. The application of single-cell RNA sequencing (scRNA-seq) analysis has discovered not only disease-related cell-specific transcriptomic profiles but also novel subpopulations of cells once thought as homogenous cell populations. Vascular cells undergo specific transcriptional changes during the entire course of the disease. Epigenetics is the instruction-set-architecture in living cells that defines and maintains the cellular identity by regulating the cellular transcriptome. Although different cells contain the same genetic material, they have different epigenomic signatures. The epigenome is plastic, dynamic and highly responsive to environmental stimuli. Modifications to the epigenome are driven by an array of epigenetic enzymes generally referred to as writers, erasers and readers that define cellular fate and destiny. The reversibility of these modifications raises hope for finding novel therapeutic targets for modifiable pathological conditions including atherosclerosis where the involvement of epigenetics is increasingly appreciated. This article provides a critical review of the up-to-date research in the field of epigenetics mainly focusing on in vivo settings in the context of the cellular role of individual vascular cell types in the development of atherosclerosis.

Cyclin G2 promotes the formation of smooth muscle cells derived foam cells in atherosclerosis via PP2A/NF-κB/LOX-1 pathway

Background

To investigate the role and underlying mechanism of cyclin G2 (G2-type cyclin) in the formation of vascular smooth muscle cells (VSMCs) derived foam cells.

Methods

The levels of α-SMA (alpha-SM-actin), p-NF-κB (phosphorylation nuclear transcription factors kappa B), and LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) were measured by immunohistochemistry and western blotting. The mouse aortic root smooth muscle cell line MOVAS was transfected to over-express cyclin G2, which were then stimulated with 80 µg/mL ox-LDL (oxidized low-density lipoprotein) to induce foam cell formation. DT-061 an activator of PP2A (protein phosphatase 2A) agonist was used to verify the role of PP2A in the process.

Results

Knocking out the Ccng2 gene in Apoe^-/- mice alleviated aortic lipid plaque, foam cell formulation, ameliorative body weight, and LDL-cholesterol. We observed that the number of α-SMA positive cells was significantly decreased in Apoe^-/-Ccng^2-/- mice compared to Apoe^-/- mice. Also, the protein levels of p-NF-κB and LOX-1 were markedly reduced in the aortic root of Apoe^-/-Ccng2^-/- mice. Upon stimulation with ox-LDL, upregulated cyclin G2 increased the intracellular lipid accumulation in MOVAS cells. Also, it suppressed the activity of PP2A but up-regulated LOX-1. Additionally, the cell nuclear translocation of p-NF-κB was increased. Interestingly, DT-061 intervention, re-activating the activity of PP2A, reduced the levels of nuclear p-NF-κB and LOX-1. This led to decreased lipid endocytosis reducing the formation of VSMCs- derived foam cells.

Conclusions

Cyclin G2 increases the nuclear translocation of p-NF-κB by reducing the enzymatic activity of PP2A and upregulating LOX-1, thereby promotes the formation of VSMCs -derived foam cells in atherosclerosis.

Role of inflammatory cytokines in genesis and treatment of atherosclerosis

Atherosclerosis demonstrates an increased rate of vascular smooth muscle cells (VSMC) plasticity characterized by switching from the differentiated contractile phenotype to a de-differentiated synthetic state. In healthy blood vessels, phenotypic switching represents a fundamental property of VSMC in maintaining vascular homeostasis. However, in atherosclerosis, it is an initial and necessary step in VSMC-derived foam cell formation. These foam cells play a decisive role in atherosclerosis progression since approximately half of all the foam cells are of VSMC origin. Our recent work showed that interferon-gamma (IFN-γ), a primary inflammatory cytokine in progressive atherosclerosis, mediates VSMC phenotype switching exclusively through upregulating mini-tryptophanyl-tRNA synthetase (mini-TrpRS). Here, we discuss the pro-atherosclerotic implication of this phenomenon that inevitably occurs in the context of a more complex regulation mediated by IFN-γ. An emerging therapeutic option for patients with progressive atherosclerosis is also discussed.

Protein deglycase DJ-1 deficiency induces phenotypic switching in vascular smooth muscle cells and exacerbates atherosclerotic plaque instability

Protein deglycase DJ‐1 (DJ‐1) is a multifunctional protein involved in various biological processes. However, it is unclear whether DJ‐1 influences atherosclerosis development and plaque stability. Accordingly, we evaluated the influence of DJ‐1 deletion on the progression of atherosclerosis and elucidate the underlying mechanisms. We examine the expression of DJ‐1 in atherosclerotic plaques of human and mouse models which showed that DJ‐1 expression was significantly decreased in human plaques compared with that in healthy vessels. Consistent with this, the DJ‐1 levels were persistently reduced in atherosclerotic lesions of ApoE^−/− mice with the increasing time fed by western diet. Furthermore, exposure of vascular smooth muscle cells (VSMCs) to oxidized low‐density lipoprotein down‐regulated DJ‐1 in vitro. The canonical markers of plaque stability and VSMC phenotypes were evaluated in vivo and in vitro. DJ‐1 deficiency in Apoe^−/− mice promoted the progression of atherosclerosis and exaggerated plaque instability. Moreover, isolated VSMCs from Apoe^−/−DJ‐1^−/− mice showed lower expression of contractile markers (α‐smooth muscle actin and calponin) and higher expression of synthetic indicators (osteopontin, vimentin and tropoelastin) and Kruppel‐like factor 4 (KLF4) by comparison with Apoe^−/−DJ‐1^+/+ mice. Furthermore, genetic inhibition of KLF4 counteracted the adverse effects of DJ‐1 deletion. Therefore, our results showed that DJ‐1 deletion caused phenotype switching of VSMCs and exacerbated atherosclerotic plaque instability in a KLF4‐dependent manner.

Integrating systematic biological and proteomics strategies to explore the pharmacological mechanism of danshen yin modified on atherosclerosis

This research utilized the systematic biological and proteomics strategies to explore the regulatory mechanism of Danshen Yin Modified (DSYM) on atherosclerosis (AS) biological network. The traditional Chinese medicine database and HPLC was used to find the active compounds of DSYM, Pharmmapper database was used to predict potential targets, and OMIM database and GeneCards database were used to collect AS targets. String database was utilized to obtain the other protein of proteomics proteins and the protein-protein interaction (PPI) data of DSYM targets, AS genes, proteomics proteins and other proteins. The Cytoscape 3.7.1 software was utilized to construct and analyse the network. The DAVID database is used to discover the biological processes and signalling pathways that these proteins aggregate. Finally, animal experiments and proteomics analysis were used to further verify the prediction results. The results showed that 140 active compounds, 405 DSYM targets and 590 AS genes were obtained, and 51 differentially expressed proteins were identified in the DSYM-treated ApoE-/- mouse AS model. A total of 4 major networks and a number of their derivative networks were constructed and analysed. The prediction results showed that DSYM can regulate AS-related biological processes and signalling pathways. Animal experiments have also shown that DSYM has a therapeutic effect on ApoE-/-mouse AS model (P < .05). Therefore, this study proposed a new method based on systems biology, proteomics, and experimental pharmacology, and analysed the pharmacological mechanism of DSYM. DSYM may achieve therapeutic effects by regulating AS-related signalling pathways and biological processes found in this research.

IRF-1 contributes to the pathological phenotype of VSMCs during atherogenesis by increasing CCL19 transcription

Atherosclerosis (AS) is a chronic inflammatory disease that mainly involves the large and middle arteries, but the specific mechanism is not precise. Chemokine ligand 19 (CCL19) has been reported highly expressed in peripheral blood of patients with atherosclerosis, but its role lacks explicit data. By ELISA assay and immunohistochemical (IHC) analysis, we found that the CCL19 was significantly up-regulated in AS. Therefore, we tried to clarify whether CCL19 expression was related to the progression of AS. QRT-PCR and western blot demonstrated that overexpression of CCL19 promoted the secretion of inflammatory factors and the deposition of the extracellular matrix, and facilitated the proliferation and migration of VSMCS. Besides, knockdown of CCL19 reduced the inflammation, collagen secretion, proliferation and migration of VSMCS induced by PGDF-BB. The results of database analysis, chromatin immunoprecipitation (ChIP) and luciferase assay showed that interferon regulatory factor 1 (IRF-1) activated the expression of CCL19 at the transcriptional level. Importantly, silencing IRF-1 inhibited atherosclerosis in high-fat-fed mice, inhibited the proliferation and migration of VSMCS, and down-regulated the expression of CCL19. Summing up, the results demonstrated that IRF-1 contributed to the pathological phenotype of VSMCs during atherogenesis by increasing CCL19 transcription.

Apoptosis, autophagy and atherosclerosis: Relationships and the role of Hsp27

Atherosclerosis is a multifactorial chronic inflammatory disease of the arterial wall, and an important pathological basis of coronary heart disease. Endothelial cells, vascular smooth muscle cells, and macrophages play important roles in the development of atherosclerosis. Of note, apoptosis and autophagy, two types of programmed cell death, influence the development and progression of atherosclerosis via the modulation of such cells. The small heat shock protein Hsp27 is a multifunctional protein induced by various stress factors and has a protective effect on cells. A large number of studies have demonstrated that Hsp27 plays an important role in regulating apoptosis. Recently, some studies have suggested that Hsp27 also participates in the autophagic process. Moreover, Hsp27 is closely related to the occurrence and development of atherosclerosis. Here, we summarize the molecular mechanisms of apoptosis and autophagy and discuss their effects on endothelial cells, vascular smooth muscle cells, and macrophages in the context of atherosclerotic procession. We further explore the involvement of Hsp27 in apoptosis, autophagy, and atherosclerosis. We speculate that Hsp27 may exert its anti-atherosclerotic role via the regulation of apoptosis and autophagy; this may provide the basis for the development of new approaches for the prevention and treatment of atherosclerosis.

Celastrol suppresses lipid accumulation through LXRα/ABCA1 signaling pathway and autophagy in vascular smooth muscle cells

The uptake of modified low-density lipoprotein (LDL) and the accumulation of lipid droplets induce the formation of vascular smooth muscle cells (VSMCs)-derived foam cells, thereby promoting the development and maturation of plaques and accelerating the progression of atherosclerosis. Celastrol is a quinine methide triterpenoid isolated from the root bark of traditional Chinese herb Tripterygium wilfordii. It possesses various biological properties, including anti-obesity, cardiovascular protection, anti-inflammation, etc. In the present study, we found that celastrol significantly reduced lipid accumulation induced by oxidized LDL (ox-LDL) in VSMCs. Mechanistically, celastrol up-regulated adenosine triphosphate-binding cassette transporter A1 (ABCA1) expression through activating liver X receptor α (LXRα) expression, which contributed to inhibit lipid accumulation in VSMCs. Meanwhile, celastrol decreased lipid accumulation by triggering autophagy in VSMCs. Therefore, these findings supported celastrol as a potentially effective agent for the prevention and therapy of atherosclerosis.

Hsa_circ_0029589 knockdown inhibits the proliferation, migration and invasion of vascular smooth muscle cells via regulating miR-214-3p and STIM1

AIMS

Circular RNAs (circRNAs) are relevant to atherosclerosis progression. However, the role and mechanism of circRNA hsa_circ_0029589 (circ_0029589) in atherosclerosis are not fully understood. This research aims to explore the function and mechanism of circ_0029589 in oxidized low-density lipoprotein (ox-LDL)-caused vascular smooth muscle cells (VSMCs) injury in vitro.

MAIN METHODS

VSMCs were challenged via ox-LDL to mimic atherosclerosis-like injury in vitro. Circ_0029589, microRNA-214-3p (miR-214-3p) and stromal interaction molecule 1 (STIM1) abundances were detected via quantitative reverse transcription polymerase chain reaction or western blot. Cell proliferation was investigated via cell viability, cycle, apoptosis and proliferation-associated protein levels. Cell migration and invasion were assessed via transwell analysis. The relationship between miR-214-3p and circ_0029589 or STIM1 was tested via dual-luciferase reporter analysis and RNA immunoprecipitation.

KEY FINDINGS

Circ_0029589 level was enhanced in ox-LDL-challenged VSMCs. Circ_0029589 interference constrained cell proliferation, migration and invasion in ox-LDL-challenged VSMCs. miR-214-3p was targeted by circ_0029589 and miR-214-3p knockdown weakened the suppressive function of circ_0029589 silence on VSMCs proliferation, migration and invasion. STIM1 was targeted via miR-214-3p and miR-214-3p could suppress VSMCs proliferation, migration and invasion via decreasing STIM1. Moreover, circ_0029589 modulated STIM1 level by miR-214-3p.

SIGNIFICANCE

Circ_0029589 knockdown repressed proliferation, migration and invasion of VSMCs challenged via ox-LDL by regulating miR-214-3p and STIM1, indicating that circ_0029589 might play important role in atherosclerosis.

Moderate Alcohol Consumption Targets S100β+ Vascular Stem Cells and Attenuates Injury-Induced Neointimal Hyperplasia

BACKGROUND

Stem cells present in the vessel wall may be triggered in response to injurious stimuli to undergo differentiation and contribute to vascular disease development. Our aim was to determine the effect of moderate alcohol (EtOH) exposure on the expansion and differentiation of S100 calcium-binding protein B positive (S100β⁺ ) resident vascular stem cells and their contribution to pathologic vessel remodeling in a mouse model of arteriosclerosis.

METHODS AND RESULTS

Lineage tracing analysis of S100β⁺ cells was performed in male and female S100β-eGFP/Cre/ERT2-dTomato transgenic mice treated daily with or without EtOH by oral gavage (peak BAC: 15 mM or 0.07%) following left common carotid artery ligation for 14 days. Carotid arteries (ligated or sham-operated) were harvested for morphological analysis and confocal assessment of fluorescent-tagged S100 β ⁺ cells in FFPE carotid cross sections. Ligation-induced carotid remodeling was more robust in males than in females. EtOH-gavaged mice had less adventitial thickening and markedly reduced neointimal formation compared to controls, with a more pronounced inhibitory effect in males compared to females. There was significant expansion of S100β⁺ -marked cells in vessels postligation, primarily in the neointimal compartment. EtOH treatment reduced the fraction of S100β⁺ cells in carotid cross sections, concomitant with attenuated remodeling. In vitro, EtOH attenuated Sonic Hedgehog-stimulated myogenic differentiation (as evidenced by reduced calponin and myosin heavy chain expression) of isolated murine S100β⁺ vascular stem cells.

CONCLUSIONS

These data highlight resident vascular S100β⁺ stem cells as a novel target population for alcohol and suggest that regulation of these progenitors in adult arteries, particularly in males, may be an important mechanism contributing to the antiatherogenic effects of moderate alcohol consumption.

Emerging Roles for Neuropilin-2 in Cardiovascular Disease

Cardiovascular disease, the leading cause of death worldwide, is predominantly associated with atherosclerosis. Atherosclerosis is a chronic inflammatory disease characterised by the narrowing of large to medium-sized arteries due to a build-up of plaque. Atherosclerotic plaque is comprised of lipids, extracellular matrix, and several cell types, including endothelial, immune, and vascular smooth muscle cells. Such narrowing of the blood vessels can itself restrict blood flow to vital organs but most severe clinical complications, including heart attacks and strokes, occur when lesions rupture, triggering the blood to clot and obstructing blood flow further down the vascular tree. To circumvent such obstructions, percutaneous coronary intervention or bypass grafts are often required; however, re-occlusion of the treated artery frequently occurs. Neuropilins (NRPs), a multifunctional family of cell surface co-receptors, are expressed by endothelial, immune, and vascular smooth muscle cells and are regulators of numerous signalling pathways within the vasculature. Here, we review recent studies implicating NRP2 in the development of occlusive vascular diseases and discuss how NRP2 could be targeted for therapeutic intervention.

Metformin and Vascular Diseases: A Focused Review on Smooth Muscle Cell Function

Metformin has been used in diabetes for more than 60 years and has excellent safety in the therapy of human type 2 diabetes (T2D). There is growing evidence that the beneficial health effects of metformin are beyond its ability to improve glucose metabolism. Metformin not only reduces the incidence of cardiovascular diseases (CVD) in T2D patients, but also reduces the burden of atherosclerosis (AS) in pre-diabetes patients. Vascular smooth muscle cells (VSMCs) function is an important factor in determining the characteristics of the entire arterial vessel. Its excessive proliferation contributes to the etiology of several types of CVD, including AS, restenosis, and pulmonary hypertension. Current studies show that metformin has a beneficial effect on VSMCs function. Therefore, this review provides a timely overview of the role and molecular mechanisms by which metformin acts through VSMCs to protect CVD.

Fibroblast Activation Protein Regulates Lesion Burden and the Fibroinflammatory Response in Apoe-Deficient Mice in a Sexually Dimorphic Manner

Fibroblast activation protein (FAP) has been established as an inducible and mesenchymal cell-specific mediator of disease progression in cancer and fibrosis. Atherosclerosis is a fibroinflammatory disease, and FAP was previously reported to be up-regulated in human atherosclerotic plaques compared with normal vessel. We investigated the spatial and temporal distribution of Fap-expressing cells in a murine model of atherosclerosis and used a genetic approach to determine if and how Fap affected disease progression. Fap was found to be expressed predominantly on vascular smooth muscle cells in lesions of athero-prone Apoe^-/- mice. Global deletion of Fap (Fap^-/-) in Apoe^-/- mice accelerated atherosclerotic disease progression in both males and females, with the effect observed earlier in males. Sex-specific effects on lesion morphology were observed. Relative levels of extracellular matrix, fibrotic, and inflammatory cell content were comparable in lesions in male mice regardless of Fap status. In contrast, lesions in Fap^-/- female mice were characterized by a more fibrotic composition due to a reduction in inflammation, specifically a reduction in Mox macrophages. Combined, these data suggest that Fap restrains the progression of atherosclerosis and may contribute to the sexually dimorphic susceptibility to atherosclerosis by regulating the balance between inflammation (an indicator of vulnerability to plaque rupture) and fibrosis (an indicator of plaque stability).

MicroRNA-21 deficiency attenuated atherogenesis and decreased macrophage infiltration by targeting Dusp-8

BACKGROUND AND AIMS

Atherosclerosis is a chronic inflammatory disorder mediated by macrophage activation. MicroRNA-21 (miR-21) is a key regulator in the macrophage inflammatory response. However, the functional role of miR-21 in atherogenesis is far from clear.

METHODS AND RESULTS

Here, we report that miR-21 is significantly upregulated in mouse atherosclerotic plaques and peripheral monocytes from patients with coronary artery disease. Compared with miR-21^+/+apoE^-/- mice (apoE^-/- mice), miR-21^-/-apoE^-/- (double knockout, DKO) mice showed less atherosclerotic lesions, reduced presence of macrophages, decreased smooth muscle cells(SMC) and collagen content in the aorta. We further explored the role of miR-21 in macrophage activation in vitro. Bone marrow-derived macrophages (BMDMs) from DKO mice not only exhibit impaired function of migration induced by chemokine (C-C motif) ligand 2 (CCL2) but also a weakened macrophage-endothelium interaction activated by tumor necrosis factor-α (TNF-α). However, atherogenic inflammatory cytokine secretion was not affected by miR-21 in vitro or in vivo. Additionally, miR-21 knockdown in BMDMs directly derepressed the expression of dual specificity protein phosphatase 8 (Dusp-8), a previously validated miR-21 target in cardiac fibroblasts, which negatively regulates mitogen-activated protein kinase (MAPK) signaling, particularly the p38-and c-Jun N-terminal kinase (JNK)-related signaling pathways.

CONCLUSIONS

These data demonstrate that inhibition of miR-21 may restrict the formation of atherosclerotic plaques partly by regulating macrophage migration and adhesion, while, reduced SMCs and collagen content in plaques may lead to a less stable phenotype with the progression of atherosclerosis. Thus, the absence of miR-21 reduces atherosclerotic lesions but may not represent all benefit in atherosclerosis development.

The role of smooth muscle cells in plaque stability: Therapeutic targeting potential

Events responsible for cardiovascular mortality and morbidity are predominantly caused by rupture of "vulnerable" atherosclerotic lesions. Vascular smooth muscle cells (VSMCs) play a key role in atherogenesis and have historically been considered beneficial for plaque stability. VSMCs constitute the main cellular component of the protective fibrous cap within lesions and are responsible for synthesising strength-giving extracellular matrix components. However, lineage-tracing experiments in mouse models of atherosclerosis have shown that, in addition to the fibrous cap, VSMCs also give rise to many of the cell types found within the plaque core. In particular, VSMCs generate a substantial fraction of lipid-laden foam cells, and VSMC-derived cells expressing markers of macrophages, osteochondrocyte, and mesenchymal stem cells have been observed within lesions. Here, we review recent studies that have changed our perspective on VSMC function in atherosclerosis and discuss how VSMCs could be targeted to increase plaque stability.

Study on the effect of LncRNA AK094457 on OX-LDL induced vascular smooth muscle cells

Atherosclerosis as the common disease has aroused many attentions worldwide. Gene target therapy has become the promising filed for atherosclerosis treatment. Herein, LncRNA AK094457 as a new promising therapy target is investigated in OX-LDL induced vascular smooth muscle cells. The Results showed that LncRNA AK094457 downregulated by shRNA-AK094457-1 have inhibiting effects on proliferation, migration, ROS level and inflammation level in OX-LDL induced vascular smooth muscle cells (VSMCs). In addition, the down regulation of lncRNA suppressed expressions of relevant proteins that are involved in TLR4/MyD88 signal pathway and enhanced expressions of relevant proteins in Nrf2/HO-1 pathway. Taken together, Down regulation of lncRNA AK094457 against effects induced by OXL-LDL in atherosclerosis via Nrf2/HO-1 and TLR4/MyD88 signal pathway is a promising avenue for atherosclerosis treatment.