Branched-chain amino acid catabolic defect in vascular smooth muscle cells drives thoracic aortic dissection via mTOR hyperactivation

Metabolic reprogramming of vascular smooth muscle cell (VSMC) plays a critical role in the pathogenesis of thoracic aortic dissection (TAD). Previous researches have mainly focused on dysregulation of fatty acid or glucose metabolism, while the impact of amino acids catabolic disorder in VSMCs during the development of TAD remains elusive. Here, we identified branched-chain amino acid (BCAA) catabolic defect as a metabolic hallmark of TAD. The bioinformatics analysis and data from human aorta revealed impaired BCAA catabolism in TAD individuals. This was accompanied by upregulated branched-chain α-ketoacid dehydrogenase kinase (BCKDK) expression and BCKD E1 subunit alpha (BCKDHA) phosphorylation, enhanced vascular inflammation, and hyperactivation of mTOR signaling. Further in vivo experiments demonstrated that inhibition of BCKDK with BT2 (a BCKDK allosteric inhibitor) treatment dephosphorylated BCKDHA and re-activated BCAA catabolism, attenuated VSMCs phenotypic switching, alleviated aortic remodeling, mitochondrial reactive oxygen species (ROS) damage and vascular inflammation. Additionally, the beneficial actions of BT2 were validated in a TNF-α challenged murine VSMC cell line. Meanwhile, rapamycin conferred similar beneficial effects against VSMC phenotypic switching, cellular ROS damage as well as inflammatory response. However, co-treatment with MHY1485 (a classic mTOR activator) reversed the beneficial effects of BT2 by reactivating mTOR signaling. Taken together, the in vivo and in vitro evidence showed that impairment of BCAA catabolism resulted in aortic accumulation of BCAA and further caused VSMC phenotypic switching, mitochondrial ROS damage and inflammatory response via mTOR hyperactivation. BCKDK and mTOR signaling may serve as the potential drug targets for the prevention and treatment of TAD.

Roles of endothelial and smooth muscle cell dysfunction and vasa vasorum in vasomotor disorders in ischemia with no obstructive coronary artery disease

Recently, the importance has emerged of ischemia with no obstructive coronary artery disease (INOCA), for which endothelial and vascular smooth muscle cell (VSMC) dysfunctions and alterations in coronary vasa vasorum are involved. Regarding endothelial vasodilator functions, both endothelium-derived nitric oxide and endothelium-derived hyperpolarizing factor play important roles in modulating vascular tone, especially in the microcirculation. Recent studies have suggested systemic endothelial dysfunction in INOCA. Regarding VSMC dysfunction, Rho-kinase has been identified as a key molecular mechanism of VSMC hyperconstriction in INOCA. Finally, recent advances of coronary imaging have demonstrated the important role of altered adventitial vasa vasorum functions in INOCA.

Murine Cytomegalovirus Infection Induced miR-1929-3p Down-Regulation Promotes the Proliferation and Apoptosis of Vascular Smooth Muscle Cells in Mice by Targeting Endothelin A Receptor and Downstream NLRP3 Activation Pathway

Our previous study demonstrated in vivo that mouse cytomegalovirus (MCMV) infection promoted vascular remodeling after downregulation of miR-1929-3p. This study aimed to investigate the role of miR-1929-3p/ETAR/NLRP3 pathway in mouse vascular smooth muscle cells (MOVAS) after MCMV infection. First, PCR was used to detect the success of the infection. Second, MOVAS were transfected with the miR-1929-3p mimic, inhibitor, and ETAR overexpressed adenovirus vector. Cell proliferation was detected using EdU, whereas apoptosis was detected using flow cytometry. The expression of miR-1929-3p and ETAR were detected using qRT-PCR. Western blot detected proteins of cell proliferation, apoptosis, and the NLRP3 inflammasome. Interleukin-1β and interleukin-18 were determined using ELISA. The results revealed that after 48 h, MCMV infection promoted the proliferation of MOVAS when the MOI was 0.01. MCMV infection increased ETAR by downregulating miR-1929-3p. The miR-1929-3p mimic reversed the proliferation and apoptosis, whereas the miR-1929-3p inhibitor promoted this effect. ETAR overexpression further promoted MCMV infection by downregulating miR-1929-3p-mediated proliferation and apoptosis. MCMV infection mediates the downregulation of miR-1929-3p and the upregulation of ETAR, which activates NLRP3 inflammasome. In conclusion, MCMV infection promoted the proliferation of MOVAS, possibly by downregulating miR-1929-3p, promoting the upregulation of the target gene ETAR and activating NLRP3 inflammasome.

Oxidative stress drives vascular smooth muscle cell damage in acute Stanford type A aortic dissection through HIF-1α/HO-1 mediated ferroptosis

Background

Acute Stanford type A aortic dissection (ATAAD) is characterized by intimal tearing and false lumen formation containing large amounts of erythrocytes with heme. Heme oxygenase 1 (HO-1) is the key enzyme to degrade heme for iron accumulation and further ferroptosis. The current study aimed at investigating the role of HO-1 in the dissection progression of ATAAD.

Methods

Bioinformatic analyses and experimental validation were performed to reveal ferroptosis and HO-1 expression in ATAAD. Human aortic vascular smooth muscle cell (HA-VSMC) was used to explore underlying molecular mechanisms and the role of HO-1 overexpression in ATAAD.

Results

Ferroptosis was identified as a critical manner of regulated cell death in ATAAD. HO-1 was screened as a key signature of ferroptosis in ATAAD, which was closely associated with oxidative stress. Single cell/nucleus transcriptomic analysis and histological staining revealed that HO-1 and HIF-1α were upregulated in vascular smooth muscle cell (VSMC) of ATAAD. Further in vitro experiments showed that H2O2-induced oxidative stress increased VSMC ferroptosis with the overexpression of HO-1, which could be suppressed by HIF-1α inhibitor PX-478. HIF-1α could transcriptionally regulate the expression of HO-1 through binding to its promoter region. Pharmacological inhibition of HO-1 by zinc protoporphyrin (ZnPP) did not reduce H2O2-induced HA-VSMC damage without heme co-incubation. However, H2O2-induced HA-VSMC damage was worsened when heme was added into the medium, and ZnPP could reduce HA-VSMC damage in this condition.

Conclusion

HO-1 is a key signature of VSMC ferroptosis in ATAAD. HIF-1α/HO-1 mediated ferroptosis might participate in oxidative stress induced VSMC damage.

PPARγ activation by fisetin mitigates vascular smooth muscle cell senescence via the mTORC2-FoxO3a-autophagy signaling pathway

Cellular senescence is caused by diverse stimuli and contributes to cardiovascular diseases. Several studies have indicated that PPARγ acts as a key mediator of lipid metabolism and shown that it has a protective effect on vascular biology. Nevertheless, the mechanism responsible for the anti-aging effects of PPARγ has not been fully elucidated in vascular smooth muscle cell (VSMC). Furthermore, although mTOR complex 2 (mTORC2) is known to be involved in cellular senescence and autophagy, relatively few studies have investigated its effects as compared with mTOR complex 1 (mTORC1). Therefore, we focused on mTORC2 function and investigated the relationship between PPARγ and mTORC2, and the anti-aging mechanism in VSMC. We found PPARγ activation dose-dependently mitigated the hydrogen peroxide (H2O2)-induced senescence. Treatment of fisetin induced the translocation of PPARγ from cytosol to nuclear and inhibited VSMC senescence. Moreover, activated PPARγ increased PTEN transcription, leading to inhibition of the mTORC2 signaling pathway. We determined mTORC2 activation contributed to senescence by suppressing the FoxO3a-autophagy signaling pathway, and dual knockdown of mTORC1 and mTORC2 decreased cellular senescence and increased autophagy activation more than respective single knockdown. Finally, fisetin acted as a PPARγ activator and inhibited VSMC senescence through the mTORC2-FoxO3a-autophagy signaling pathway. These results demonstrate PPARγ is associated with cellular senescence and that fisetin has an anti-aging effect via PPARγ activation and mTORC2 inhibition in VSMC. These results demonstrate that the mTORC2 signaling pathway regulates autophagy and cellular senescence, which suggests mTORC2 should be considered a significant target for preventing cellular senescence and age-related diseases.

Role of TRPV4 on vascular tone regulation in pathophysiological states

Vascular tone regulation is a key event in controlling blood flow in the body. Endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) help regulate the vascular tone. Abnormal vascular responsiveness to various stimuli, including constrictors and dilators, has been observed in pathophysiological states although EC and VSMC coordinate to maintain the exquisite balance between contraction and relaxation in vasculatures. Thus, investigating the mechanisms underlying vascular tone abnormality is very important in maintaining vascular health and treating vasculopathy. Increased intracellular free Ca2+ concentration ([Ca2+]i) is one of the major triggers initiating each EC and VSMC response. Transient receptor potential vanilloid family member 4 (TRPV4) is a Ca2+-permeable non-selective ion channel, which is activated by several stimuli, and is presented in both ECs and VSMCs. Therefore, TRPV4 plays an important role in vascular responses. Emerging evidence indicates the role of TRPV4 on the functions of ECs and VSMCs in various pathophysiological states, including hypertension, diabetes, and obesity. This review focused on the link between TRPV4 and the functions of ECs/VSMCs, particularly its role in vascular tone and responsiveness to vasoactive substances.

Detection of cell-type-enriched long noncoding RNAs in atherosclerosis using single-cell techniques: A brief review

Cardiovascular diseases are the leading causes of mortality and morbidity worldwide. Atherosclerotic plaque underlies the predominant factors and is composed of various cell types, including structure cells, such as endothelial and smooth muscle cells, and immune cells, such as macrophages and T cells. Single-cell RNA sequencing (scRNA-seq) has been extensively applied to decipher these cellular heterogeneities to expand our understanding on the mechanisms of atherosclerosis (AS) and to facilitate identifying cell-type-specific long noncoding RNAs (LncRNAs). LncRNAs have been demonstrated to deeply regulate biological activities at the transcriptional and post-transcriptional levels. A group of well-documented functional lncRNAs in AS have been studied. In our review, we selectively described several lncRNAs involved in the critical process of AS. We highlighted four novel lncRNAs (lncRNA CARMN, LINC00607, PCAT19, LINC01235) detected in scRNA-seq datasets and their functions in AS. We also reviewed open web source and bioinformatic tools, as well as the latest methods to perform an in-depth study of lncRNAs. It is fundamental to annotate functional lncRNAs in the various biological activities of AS, as lncRNAs may represent promising targets in the future for treatment and diagnosis in clinical practice.

CypD induced ROS output promotes intracranial aneurysm formation and rupture by 8-OHdG/NLRP3/MMP9 pathway

Reactive Oxygen Species (ROS) are widely accepted as a pernicious factor in the progression of intracranial aneurysm (IA), which is eminently related to cell apoptosis and extracellular matrix degradation, but the mechanism remains to be elucidated. Recent evidence has identified that enhancement of Cyclophilin D (CypD) under stress conditions plays a critical role in ROS output, thus accelerating vascular destruction. However, no study has confirmed whether cypD is a detrimental mediator of cell apoptosis and extracellular matrix degradation in the setting of IA development. Our data indicated that endogenous cypD mRNA was significantly upregulated in human IA lesions and mouse IA wall, accompanied by higher level of ROS, MMPs and cell apoptosis. CypD-/- remarkably reversed vascular smooth muscle cells (VSMCs) apoptosis and elastic fiber degradation, and significantly decreased the incidence of aneurysm and ruptured aneurysm, together with the downregulation of ROS, 8-OHdG, NLRP3 and MMP9 in vivo and vitro. Furthermore, we demonstrated that blockade of cypD with CsA inhibited the above processes, thus preventing IA formation and rupture, these effects were highly dependent on ROS output. Mechanistically, we found that cypD directly interacts with ATP5B to promote ROS release in VSMCs, and 8-OHdG directly bind to NLRP3, which interacted with MMP9 to increased MMP9 level and activity in vivo and vitro. Our data expound an unexpected role of cypD in IA pathogenesis and an undescribed 8-OHdG/NLRP3/MMP9 pathway involved in accelerating VSMCs apoptosis and elastic fiber degradation. Repressing ROS output by CypD inhibition may be a promising therapeutic strategy for prevention IA development.

New Targets in Atherosclerosis: Vascular Smooth Muscle Cell Plasticity and Macrophage Polarity

PURPOSE

Despite an increase in treatment options, and substantial reductions in cardiovascular mortality over the past half-century, atherosclerosis remains the most prevalent cause of premature mortality worldwide. The development of innovative new therapies is crucial to further minimize atherosclerosis-related deaths. The diverse array of cell phenotypes derived from vascular smooth muscle cells (SMCs) and macrophages within atherosclerotic plaques are increasingly becoming recognized for their beneficial and detrimental roles in plaque stability and disease burden. This review explores how contemporary transcriptomics and fate-mapping studies have revealed vascular cell plasticity as a relatively unexplored target for therapeutic intervention.

METHODS

Recent literature for this narrative review was obtained by searching electronic databases (ie, Google Scholar, PubMed). Additional studies were sourced from reference lists and the authors' personal databases.

FINDINGS

The lipid-rich and inflammatory plaque milieu induces SMC phenotypic switching to both beneficial and detrimental phenotypes. Likewise, macrophage heterogeneity increases with disease burden to a variety of pro-inflammatory and anti-inflammatory activation states. These vascular cell phenotypes are determinants of plaque structure stability, and it is therefore highly likely that they influence clinical outcomes. Development of clinical treatments targeting deleterious phenotypes or promoting pro-healing phenotypes remains in its infancy. However, existing treatments (statins) have shown beneficial effects toward macrophage polarization, providing a rationale for more targeted approaches. In contrast, beneficial SMC phenotypic modulation with these pharmacologic agents has yet to be achieved. The range of modulated vascular cell phenotypes provides a multitude of novel targets and the potential to reduce future adverse events.

IMPLICATIONS

Vascular cell phenotypic heterogeneity must continue to be explored to lower cardiovascular events in the future. The rapidly increasing weight of evidence surrounding the role of SMC plasticity and macrophage polarity in plaque vulnerability provides a strong foundation upon which development of new therapeutics must follow. This approach may prove to be crucial in reducing cardiovascular events and improving patient benefit in the future.

Sodium-glucose cotransporter 2 inhibitor canagliflozin alleviates vascular calcification through suppression of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 inflammasome

AIMS

Vascular calcification (VC) is prevalent in pathological processes such as diabetes, chronic kidney disease (CKD), and atherosclerosis, but effective therapies are still lacking by far. Canagliflozin (CANA), a sodium-glucose cotransporter 2 inhibitor, has been approved for the treatment of type 2 diabetes mellitus and exhibits beneficial effects against cardiovascular disease. However, the effect of CANA on VC remains unknown. In this study, we hypothesize that CANA protects against VC.

METHODS AND RESULTS

Micro-computed tomography analysis and alizarin red staining revealed that CANA treatment prevented aortic calcification in CKD rats and in VitD3-overloaded mice. Moreover, CANA alleviated the calcification of rat and human arterial rings. Alizarin red staining revealed that calcification of rat and human vascular smooth muscle cells (VSMCs) was attenuated by CANA treatment and this phenomenon was confirmed by calcium content assay. In addition, CANA downregulated the expression of osteogenic differentiation markers Runx2 and BMP2. Of interest, qPCR and western blot analysis revealed that CANA downregulated the expression of the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3), and the downstream signalling molecules Caspase-1 and IL-1β in VSMCs as well. Both NLRP3 inhibitor MCC950 and knockdown of NLRP3 by siRNA independently resulted in decreased calcification of VSMCs. By contrast, activation of NLRP3 exacerbated VSMC calcification, and this effect was prevented by the addition of CANA.

CONCLUSIONS

Our study for the first time demonstrates that CANA exerts a protective effect on VC at least partially via suppressing the NLRP3 signalling pathway. Therefore, supplementation of CANA as well as inhibition of NLRP3 inflammasome presents a potential therapy for VC.

Role of leptin in the pathophysiology of preeclampsia

Preeclampsia (PE) is a severe pregnancy complication. The exact pathogenesis of PE remains unclear, but it is related to immune, inflammatory, circulatory, and oxidative stress factors. Leptin is a protein involved in these processes and is essential for maintaining a normal pregnancy and healthy fetal growth. Abnormal increases in leptin levels have been observed in the peripheral blood and placenta of patients with PE. Disturbances in leptin can affect the proliferation and hypertrophy of vascular smooth muscle cells, which are important for placentation. Leptin also regulates arterial tension and trophoblast function in pregnant women. In addition, consistently high levels of leptin are linked to hyperactive inflammation and oxidative stress reactions in both patients with PE and animal models. This review focuses on the role of leptin in the pathophysiology of PE and elucidates its potential mechanisms.

MiR-21-3p in extracellular vesicles from vascular fibroblasts of spontaneously hypertensive rat promotes proliferation and migration of vascular smooth muscle cells

Enhanced proliferation and migration of vascular smooth muscle cells (VSMCs) contributes to vascular remodeling in hypertension. Adventitial fibroblasts (AFs)-derived extracellular vesicles (EVs) modulate vascular remodeling in spontaneously hypertensive rat (SHR). This study shows the important roles of EVs-mediated miR-21-3p transfer in VSMC proliferation and migration and underlying mechanisms in SHR. AFs and VSMCs were obtained from aorta of Wistar-Kyoto rat (WKY) and SHR. EVs were separated from AFs culture with ultracentrifugation method. MiR-21-3p content in the EVs of SHR was increased compared with those of WKY. MiR-21-3p mimic promoted VSMC proliferation and migration of WKY and SHR, while miR-21-3p inhibitor attenuated proliferation and migration only in the VSMCs of SHR. EVs of SHR stimulated VSMC proliferation and migration, which were attenuated by miR-21-3p inhibitor. Sorbin and SH3 domain containing 2 (SORBS2) mRNA and protein levels were reduced in the VSMCs of SHR. MiR-21-3p mimic inhibited, while miR-21-3p inhibitor promoted SORBS2 expressions in the VSMCs of both WKY and SHR. EVs of SHR reduced SORBS2 expression, which was prevented by miR-21-3p inhibitor. EVs of WKY had no significant effect on SORBS2 expressions. SORBS2 overexpression attenuated the roles of miR-21-3p mimic and EVs of SHR in promoting VSMC proliferation and migration of SHR. Overexpression of miR-21-3p in vivo promotes vascular remodeling and hypertension. These results indicate that miR-21-3p in the EVs of SHR promotes VSMC proliferation and migration via negatively regulating SORBS2 expression.

Protease-Activated Receptor 2 Controls Vascular Smooth Muscle Cell Proliferation in Cyclic AMP-Dependent Protein Kinase/Mitogen-Activated Protein Kinase Kinase 1/2-Dependent Manner

INTRODUCTION

Cardiovascular disorders are characterized by vascular smooth muscle (VSM) transition from a contractile to proliferative state. Protease-activated receptor 2 (PAR2) involvement in this phenotypic conversion remains unclear. We hypothesized that PAR2 controls VSM cell proliferation in phenotype-dependent manner and through specific protein kinases.

METHODS

Rat clonal low (PLo; P3-P6) and high passage (PHi; P10-P15) VSM cells were established as respective models of quiescent and proliferative cells, based on reduced PKG-1 and VASP. Western blotting determined expression of cytoskeletal/contractile proteins, PAR2, and select protein kinases. DNA synthesis and cell proliferation were measured 24-72 h following PAR2 agonism (SLIGRL; 100 nM-10 μm) with/without PKA (PKI; 10 μm), MEK1/2 (PD98059; 10 μm), and PI3K (LY294002; 1 μm) blockade.

RESULTS

PKG-1, VASP, SM22α, calponin, cofilin, and PAR2 were reduced in PHi versus PLo cells. Following PAR2 agonism, DNA synthesis and cell proliferation increased in PLo cells but decreased in PHi cells. Western analyses showed reduced PKA, MEK1/2, and PI3K in PHi versus PLo cells, and kinase blockade revealed PAR2 controls VSM cell proliferation through PKA/MEK1/2.

DISCUSSION

Findings highlight PAR2 and PAR2-driven PKA/MEK1/2 in control of VSM cell growth and provide evidence for continued investigation of PAR2 in VSM pathology.

Unraveling the mysteries of spiral artery remodeling

Spiral artery remodeling is the process by which the uterine vessels become large bore low resistance conduits, allowing delivery of high volumes of maternal blood to the placenta to nourish the developing fetus. Failure of this process is associated with the pathophysiology of most of the major obstetric complications, including late miscarriage, fetal growth restriction and pre-eclampsia. However, the point at which remodeling 'fails' in these pathological pregnancies is not yet clear. Spiral artery remodeling has predominantly been described in terms of its morphological features, however we are starting to understand more about the cellular and molecular triggers of the different aspects of this process. This review will discuss the current state of knowledge of spiral artery remodeling, in particular the processes involved in loss of the vascular smooth muscle cells, and consider where in the process defects would lead to a pathological pregnancy.

Kv1.3 mediates ox-LDL-induced vascular smooth muscle cell proliferation through JAK2/STAT3 signaling pathway

Kv1.3 channel has been shown to participate in regulating inflammatory activation, proliferation and apoptosis in several cell types. However, most of those existing studies focused on the ion-conducting properties of Kv1.3 in maintaining the resting potential and regulating Ca2+ influx. The aim of our study was to explore whether the Kv1.3-JAK2/STAT3 signaling pathway was involved in oxidized low density lipoprotein (ox-LDL) induced vascular smooth muscle cell (VSMC) proliferation. VSMCs from mouse aorta were cultured and treated with ox-LDL (25 μg/mL). The cell counting kit-8 was used to assess cell proliferation, and western blotting was performed to detect expression levels of Kv1.3, JAK2/STAT3, phosphorylated JAK2/STAT3, cyclin B1 and cyclin D1 in treated VSMCs. VSMCs were transfected with Kv1.3 small interfering RNA (Kv1.3-siRNA) or infected with a Kv1.3 lentiviral expression vector (Lv-Kv1.3) and treated with a JAK2 inhibitor LY2784544 to assess the role of Kv1.3 and JAK2/STAT3 signaling in mediating VSMC proliferation induced by ox-LDL. Ox-LDL induced cell proliferation and upregulated the expression of Kv1.3 in mouse VSMCs. In VSMCs transfected with Kv1.3-siRNA, ox-LDL was not efficient in inducing cell proliferation or the levels of proliferation associated proteins, cyclin B1 and cyclin D1. However, cell proliferation, cyclin B1 and cyclin D1 levels increased in VSMCs infected with Lv-Kv1.3. Levels of phosphorylated JAK2 and STAT3 were increased in ox-LDL-treated VSMCs, and this increase was prevented in VSMCs transfected with Kv1.3-siRNA. Treatment with the JAK2 inhibitor LY2784544 also prevented the increase in VSMCs proliferation treated with ox-LDL. Our findings demonstrated that Kv1.3 promoted proliferation of VSMCs treated with ox-LDL, and that this effect might be mediated through activation of the JAK2/STAT3 signaling pathway.

Nemopilema nomurai jellyfish venom attenuates phenotypic modulation of PDGF BB-induced vascular smooth muscle cells and κ-carrageenan-induced rat tail thrombosis

Jellyfish venoms have long been recognized as a potentially rich source of natural bioactive compounds with pharmacological potential for the creation of innovative drugs. Our previous study demonstrated that Nemopilema nomurai jellyfish venom (NnV) has a chymotrypsin-like serine protease with fibrinolytic activity in vitro. Therefore, the present study aims to investigate the potential effect of NnV on cell migration, proliferation, and differentiation of vascular smooth muscle cells (VSMC; A7r5 cells) involved in the probable mechanism pathways. We also determined its anti-thrombotic effect through κ-carrageenan-induced Sprague-Dawley (SD) rat tail thrombus model. NnV inhibits on Platelet-derived growth factor (PDGF)-BB-stimulated A7r5 cells migration and proliferation by decreasing matrix metalloproteinase 2 (MMP-2) level and phosphorylation of ERK and Akt in a dose-dependent manner, but not p38. Furthermore, NnV regulates the phenotype transition of differentiation in PDGF-BB-stimulated A7r5 cells via ɑ-SMA and calponin in a dose-dependent manner. In an in vivo study, NnV treatment demonstrated clear anti-thrombotic activity in a dose-dependent manner, which was associated with decreased thrombus formation and length in κ-carrageenan-induced SD rat tail. These findings suggested that NnV has a novel fibrinolytic enzyme that can be used to prevent and/or treat thrombosis-related cardiovascular disorders.

Long-term, in vivo therapeutic effects of a single dose of miR-145 micelles for atherosclerosis

Atherosclerosis is a chronic inflammatory disease that is characterized by the build-up of lipid-rich plaques in the arterial walls. The standard treatment for patients with atherosclerosis is statin therapy aimed to lower serum lipid levels. Despite its widespread use, many patients taking statins continue to experience acute events. Thus, to develop improved and alternative therapies, we previously reported on microRNA-145 (miR-145 micelles) and its ability to inhibit atherosclerosis by targeting vascular smooth muscle cells (VSMCs). Importantly, one dose of miR-145 micelles significantly abrogated disease progression when evaluated two weeks post-administration. Thus, in this study, to evaluate how long the sustained effects of miR-145 micelles can be maintained and towards identifying a dosing regimen that is practical for patients with chronic disease, the therapeutic effects of a single dose of miR-145 micelles were evaluated for up to two months in vivo. After one and two months post-treatment, miR-145 micelles were found to reduce plaque size and overall lesion area compared to all other controls including statins without causing adverse effects. Furthermore, a single dose of miR-145 micelle treatment inhibited VSMC transdifferentiation into pathogenic macrophage-like and osteogenic cells in plaques. Together, our data shows the long-term efficacy and sustained effects of miR-145 micelles that is amenable using a dosing frequency relevant to chronic disease patients.

The Chinese medicine Xin-tong-tai granule protects atherosclerosis by regulating oxidative stress through NOX/ROS/NF-κB signal pathway

BACKGROUND

Xin-tong-tai Granule (XTTG), a traditional Chinese medicine, has been used to treat atherosclerosis (AS), but its mechanism is poorly understood. Intriguingly, oxidative stress has been recognized as vital factors in the treatment of atherosclerosis.

PURPOSE

This study aims to explore the potential mechanism of XTTG for treating AS.

METHODS

An in-vivo model of AS was established by feeding ApoE-/- mice with a high-fat diet (HFD), and the Human Aortic Vascular Smooth Muscle Cells (HAVSMCs) were induced by oxidized low-density lipoprotein (ox-LDL) in vitro. After treatment, the blood lipid levels and pathological aortic changes of each group were observed, and the cell proliferation and lipid droplet aggregation in each group were evaluated. The oxidative stress indicators such as malondialdehyde (MDA) and superoxide dismutase (SOD) levels and related NOX/ROS/NF-κB signaling pathway indicators were observed.

RESULTS

XTTG improved blood lipid levels and pathological aortic changes of ApoE-/- mice with HFD feeding, inhibited HAVSMCs proliferation and lipid droplet aggregation induced by ox-LDL, reduced MDA content, increased SOD content, inhibited NOX4 and p22phox protein expression, downregulated ROS content, inhibited IKK-α, IKK-β, NF-κB protein and mRNA expression and the phosphorylation of NF-κB.

CONCLUSION

XTTG can inhibit NOX/ROS/NF-κB signaling pathway, reduce damages caused by oxidative stress, and exert anti-AS effects.

BRD4770 inhibits vascular smooth muscle cell proliferation via SUV39H2, but not EHMT2 to protect against neointima formation

The behavior of vascular smooth muscle cells (VSMCs) contributes to the formation of neointima. We previously found that EHMT2 suppressed autophagy activation in VSMCs. BRD4770, an inhibitor of EHMT2/G9a, plays a critical role in several kinds of cancers. However, whether and how BRD4770 regulates the behavior of VSMCs remain unknown. In this study, we evaluate the cellular effect of BRD4770 on VSMCs by series of experiments in vivo and ex vivo. We demonstrated that BRD4770 inhibited VSMCs' growth by blockage in G2/M phase in VSMCs. Moreover, our results demonstrated that the inhibition of proliferation was independent on autophagy or EHMT2 suppression which we previous reported. Mechanistically, BRD4770 exhibited an off-target effect from EHMT2 and our further study reveal that the proliferation inhibitory effect by BRD4770 was associated with suppressing on SUV39H2/KTM1B. In vivo, BRD4770 was also verified to rescue VIH. Thus, BRD4770 function as a crucial negative regulator of VSMC proliferation via SUV39H2 and G2/M cell cycle arrest and BRD4770 could be a molecule for the therapy of vascular restenosis.

The roles of METTL3 on autophagy and proliferation of vascular smooth muscle cells are mediated by mTOR rather than by CDK1

BACKGROUND

Aberrant proliferation of vascular smooth muscle cells (VSMCs) is the cause of neointima formation followed by vascular injury. Autophagy is involved in this pathological process, but its function is controversial. Recently, we found that methyltransferase like 3 (METTL3) inhibited VSMC proliferation by activating autophagosome formation. Moreover, we also demonstrated that METTL3 reduced the levels of phosphorylated mammalian target of rapamycin (p-mTOR) and cyclin dependent kinase 1 (p-CDK1/CDC2), which were critical for autophagy and proliferation regulation. However, whether mTOR and CDK1 mediated the function of METTL3 on autophagy and proliferation in VSMCs remains unknown.

RESULTS

We showed that the activator of mTOR, MHY1485 largely reversed the effects of METTL3 overexpression on VSMC autophagy and proliferation. Rapamycin, the inhibitor of mTOR, obviously nullified the pro-proliferation effects of METTL3 knockdown by activating autophagy in VSMCs. Unexpectedly, mTOR did not contribute to the impacts of METTL3 on migration and phenotypic switching of VSMCs. On the other hand, by knockdown of CDK1 in VSMC with METTL3 deficiency, we demonstrated that CDK1 was involved in METTL3-regulated proliferation of VSMCs, but this effect was not mediated by autophagy.

CONCLUSIONS

We concluded that mTOR but not CDK1 mediated the role of METTL3 on VSMC proliferation and autophagy.

The adverse effect of anticancer drug toremifene on vascular smooth muscle cells is an important aspect of its tumor growth inhibition

PURPOSE

Toremifene (TOR) is widely used as an antineoplastic drug and has an inhibitory effect on angiogenesis in mesenteric desmoid tumors and vascular intracranial solitary fibrous tumors. However, no study has investigated the direct effect of TOR on vascular cells. This study aimed at exploring the effect of TOR on the behaviors of vascular smooth muscle cells (VSMCs).

METHODS

Human aortic umbilical vascular smooth muscle cells (HAVSMCs) were treated by TOR. Cell morphology, migration, adhesion, and proliferation assay were investigated. The cell cycle, apoptosis, mitochondrial membrane potential, and reactive oxygen species were assessed using flow cytometry. Caspase-3 and 9 activities were assayed using Caspase-3 and Caspase-9 Activity Assay kits, respectively. Immunofluorescence and Western blot assays were carried out to characterize protein expressions of PCNA, p53, and Rho/ROCK signaling pathway.

RESULTS

TOR damaged cytoskeleton, inhibited VSMC proliferation, migration, and adhesion, and induced abnormal cell morphology and apoptosis. The antiproliferative activity of TOR was associated with the induction of G0/G1 phase arrest, blocking the cell cycle. TOR disrupted intracellular reactive oxygen species and mitochondrial membrane potential, and enhanced p53 expression and the activities of caspase-3 and caspase-9. Thus, TOR-induced apoptosis by the mitochondrial signaling pathway. Additionally, TOR induced decreased Rho, ROCK, MLC, and pMLC proteins. Collectively, TOR may affect multiple behaviors of VSMCs by damaging cytoskeleton through the Rho/ROCK pathway.

CONCLUSION

The adverse effect of TOR on VSMCs could be considered as an important aspect of tumor growth inhibition.

LncRNA RP4-639F20.1 interacts with THRAP3 to attenuate atherosclerosis by regulating c-FOS in vascular smooth muscle cells proliferation and migration

BACKGROUND AND AIMS

The aberrant proliferation and migration of vascular smooth muscle cells (VSMCs) play an essential role in the pathogenesis of atherosclerosis (AS). Long noncoding RNAs (lncRNAs) have been reported as important regulators in a number of diseases. However, very little is known regarding the functional role of lncRNAs in governing proliferation and migration of VSMCs and AS development.

METHODS

Both in vitro and in vivo assays were performed to investigate the role of lncRNA in the pathophysiology of AS. Our previous lncRNA arrays revealed that lncRNA RP4-639F20.1 was significantly decreased in atherosclerotic plaques. Lentivirus overexpressing RP4-639F20.1 and lncRNA RP4-639F20.1 silencing vectors (Si-lnc-RP4-639F20.1) were constructed and transfected in VSMCs. The in vitro functions of lncRNA were analyzed by CCK-8 assays, EdU assays, scratch wound assays, transwell assays, qRT-PCR and Western blot analyses. RNA fluorescence in situ hybridization, immunoprecipitation and mRNA microarrays were used to explore the underlying mechanism. Adeno-associated-virus-9 (AAV9) overexpressing RP4-639F20.1 was constructed and injected intravenously into ApoE-/- mice to explore the role of lncRNA in vivo.

RESULTS

In vitro experiments showed that lncRNA RP4-639F20.1 interacted with THRAP3 and downregulated c-FOS expression. Both increase of lncRNA RP4-639F20.1 expression and knockdown of c-FOS inhibited the expression of MMP10 and VEGF-α in VSMCs and suppressed VSMCs proliferation and migration. In vivo experiments using ApoE-/- mice fed a high-fat diet demonstrated that lncRNA RP4-639F20.1 overexpression deterred atherosclerosis and decreased lipid levels in atherosclerotic lesions. Patients with coronary artery disease were found to have higher c-FOS levels than healthy individuals and c-FOS expression was positively correlated with the SYNTAX score of patients.

CONCLUSIONS

Overall, these data indicated that lncRNA RP4-639F20.1/THRAP3/c-FOS pathway protects against the development of atherosclerosis by suppressing VSMCs proliferation and migration. LncRNA RP4-639F20.1 and c-FOS could represent potential therapeutic targets to ameliorate atherosclerosis-related diseases.

The translational landscape of human vascular smooth muscle cells identifies novel short open reading frame-encoded peptide regulators for phenotype alteration

AIMS

The plasticity of vascular smooth muscle cells (VSMCs) enables them to alter phenotypes under various physiological and pathological stimuli. The alteration of VSMC phenotype is a key step in vascular diseases, including atherosclerosis. Although the transcriptome shift during VSMC phenotype alteration has been intensively investigated, uncovering multiple key regulatory signalling pathways, the translatome dynamics in this cellular process, remain largely unknown. Here, we explored the genome-wide regulation at the translational level of human VSMCs during phenotype alteration.

METHODS AND RESULTS

We generated nucleotide-resolution translatome and transcriptome data from human VSMCs undergoing phenotype alteration. Deep sequencing of ribosome-protected fragments (Ribo-seq) revealed alterations in protein synthesis independent of changes in messenger ribonucleicacid levels. Increased translational efficiency of many translational machinery components, including ribosomal proteins, eukaryotic translation elongation factors and initiation factors were observed during the phenotype alteration of VSMCs. In addition, hundreds of candidates for short open reading frame-encoded polypeptides (SEPs), a class of peptides containing 200 amino acids or less, were identified in a combined analysis of translatome and transcriptome data with a high positive rate in validating their coding capability. Three evolutionarily conserved SEPs were further detected endogenously by customized antibodies and suggested to participate in the pathogenesis of atherosclerosis by analysing the transcriptome and single cell RNA-seq data from patient atherosclerotic artery samples. Gain- and loss-of-function studies in human VSMCs and genetically engineered mice showed that these SEPs modulate the alteration of VSMC phenotype through different signalling pathways, including the mitogen-activated protein kinase pathway and p53 pathway.

CONCLUSION

Our study indicates that an increase in the capacity of translation, which is attributable to an increased quantity of translational machinery components, mainly controls alterations of VSMC phenotype at the level of translational regulation. In addition, SEPs could function as important regulators in the phenotype alteration of human VSMCs.

Gasdermin D affects aortic vascular smooth muscle cell pyroptosis and Ang II-induced vascular remodeling

Vascular smooth muscle cells (VSMCs) are primarily responsible for vasoconstriction and the regulation of blood pressure1. Pyroptosis, a particular form of regulated cell death, is involved in multiple vascular injuries, including hypertensive vascular dysfunction. This pyroptotic cell death is mediated by the pore-forming protein of Gasdermin D (GSDMD). This study was designed to examine the direct effect of GSDMD on smooth muscle cell pyroptosis and vascular remodeling. Findings revealed that GSDMD was activated in Angiotensin (Ang) II- treated aortas. We then showed that genetic deletion of Gsdmd reduced vascular remodeling and aorta pyroptosis induced by Ang II in vivo. Aberrant expression of GSDMD by recombinant AAV9 virus carrying Gsdmd cDNA aggravated the level of pyroptosis in aortas of Ang II mice. Gain- and loss-of- function analysis further confirmed that GSDMD regulated the pyroptosis of murine aortic vascular smooth muscle cells (MOVAS) in an in vitro model of tumor necrosis factor (TNF)-α treatment, which was achieved by transfecting expressing plasmid or siRNA, respectively. Overall, this study provided evidence supporting the active involvement of GSDMD in smooth muscle cell pyroptosis and Ang II-induced mice vascular injury. This finding lends credence to GSDMD as a potential therapeutic target for hypertensive vascular remodeling via inhibiting pyroptosis.

sGC agonist BAY1021189 promotes thoracic aortic dissection formation by accelerating vascular smooth muscle cell phenotype switch

Thoracic aortic dissection (TAD) is common but lethal cardiovascular disease with high mortality. This study aimed to expound whether and how sGC-PRKG1 signaling pathway might promote the formation of TAD. Our work identified two modules with high relevance to TAD using WGCNA method. Combined with previous studies, we focused on the participation of endothelial NOS (eNOS) in the progression of TAD. Through immunohistochemistry, immunofluorescence and western blot we verified that eNOS expression was elevated in the tissues of patients and mice with aortic dissection, and the phosphorylation Ser1177 of eNOS was activated. In a BAPN-induced TAD mouse model, sGC-PRKG1 signaling pathway promotes TAD formation by inducing vascular smooth muscle cells (VSMCs) phenotype transition, which was demonstrated as a decrease in markers of the contractile phenotype of VSMCs such as αSMA, SM22α, and Calponin. These results were also verified by experiments in vitro. To explore the further mechanism, we conducted immunohistochemistry, western blot and quantitative RT-PCR (qPCR), the results of which indicated that sGC-PRKG1 signaling pathway was activated when TAD occurred. In conclusion, our current study revealed that sGC-PRKG1 signaling pathway could promote TAD formation by accelerating VSMCs phenotype switch.