A mouse model of vascular injury that induces rapid onset of medial cell apoptosis followed by reproducible neointimal hyperplasia

Corilagin relieves atherosclerosis via the toll-like receptor 4 signaling pathway in vascular smooth muscle cells

INTRODUCTION

Corilagin possesses a diverse range of pharmacologic bioactivities. However, the specific protective effects and mechanisms of action of corilagin in the context of atherosclerosis remain unclear. In this study, we investigated the impact of corilagin on the toll-like receptor (TLR)4 signaling pathway in a mouse vascular smooth muscle cell line (MOVAS) stimulated by oxidized low-density lipoprotein (ox-LDL). Additionally, we examined the effects of corilagin in Sprague-Dawley rats experiencing atherosclerosis.

METHODS

The cytotoxicity of corilagin was assessed using the CCK8 assay. MOVAS cells, pre-incubated with ox-LDL, underwent treatment with varying concentrations of corilagin. TLR4 expression was modulated by either downregulation through small interfering (si)RNA or upregulation via lentivirus transfection. Molecular expression within the TLR4 signaling pathway was analyzed using real-time polymerase chain reaction (PCR) and Western blotting. The proliferation capacity of MOVAS cells was determined through cell counting. In a rat model, atherosclerosis was induced in femoral arteries using an improved guidewire injury method, and TLR4 expression in plaque areas was assessed using immunofluorescence. Pathological changes were examined through hematoxylin and eosin staining, as well as Oil-Red-O staining.

RESULTS

Corilagin demonstrated inhibitory effects on the TLR4 signaling pathway in MOVAS cells pre-stimulated with ox-LDL, consequently impeding the proliferative impact of ox-LDL. The modulation of TLR4 expression, either through downregulation or upregulation, similarly influenced the expression of downstream molecules. In an in vivo context, corilagin exhibited the ability to suppress TLR4 and MyD88 expression in the plaque lesion areas of rat femoral arteries, thereby alleviating the formation of atherosclerotic plaques.

CONCLUSION

Corilagin can inhibit the TLR4 signaling pathway in VSMCs, possibly by downregulating TLR4 expression and, consequently, relieving atherosclerosis.

Nox1-based NADPH oxidase regulates the Par protein complex activity to control cell polarization

Cell migration is essential for many biological and pathological processes. Establishing cell polarity with a trailing edge and forming a single lamellipodium at the leading edge of the cell is crucial for efficient directional cell migration and is a hallmark of mesenchymal cell motility. Lamellipodia formation is regulated by spatial-temporal activation of the small GTPases Rac and Cdc42 at the front edge, and RhoA at the rear end. At a molecular level, partitioning-defective (Par) protein complex comprising Par3, Par6, and atypical Protein Kinase (aPKC isoforms ζ and λ/ι) regulates front-rear axis polarization. At the front edge, integrin clustering activates Cdc42, prompting the formation of Par3/Par6/aPKC complexes to modulate MTOC positioning and microtubule stabilization. Consequently, the Par3/Par6/aPKC complex recruits Rac1-GEF Tiam to activate Rac1, leading to lamellipodium formation. At the rear end, RhoA-ROCK phosphorylates Par3 disrupting its interaction with Tiam and inactivating Rac1. RhoA activity at the rear end allows the formation of focal adhesions and stress fibers necessary to generate the traction forces that allow cell movement. Nox1-based NADPH oxidase is necessary for PDGF-induced migration in vitro and in vivo for many cell types, including fibroblasts and smooth muscle cells. Here, we report that Nox1-deficient cells failed to acquire a normal front-to-rear polarity, polarize MTOC, and form a single lamellipodium. Instead, these cells form multiple protrusions that accumulate Par3 and active Tiam. The exogenous addition of H2O2 rescues this phenotype and is associated with the hyperactivation of Par3, Tiam, and Rac1. Mechanistically, Nox1 deficiency induces the inactivation of PP2A phosphatase, leading to increased activation of aPKC. These results were validated in Nox1y/- primary mouse aortic smooth muscle cells (MASMCs), which also showed PP2A inactivation after PDGF-BB stimulation consistent with exacerbated activation of aPKC. Moreover, we evaluated the physiological relevance of this signaling pathway using a femoral artery wire injury model to generate neointimal hyperplasia. Nox1y/- mice showed increased staining for the inactive form of PP2A and increased signal for active aPKC, suggesting that PP2A and aPKC activities might contribute to reducing neointima formation observed in the arteries of Nox1y/- mice.

Cellular mechanisms of oligoclonal vascular smooth muscle cell expansion in cardiovascular disease

AIMS

Quiescent, differentiated adult vascular smooth muscle cells (VSMCs) can be induced to proliferate and switch phenotype. Such plasticity underlies blood vessel homeostasis and contributes to vascular disease development. Oligoclonal VSMC contribution is a hallmark of end-stage vascular disease. Here, we aim to understand cellular mechanisms underpinning generation of this VSMC oligoclonality.

METHODS AND RESULTS

We investigate the dynamics of VSMC clone formation using confocal microscopy and single-cell transcriptomics in VSMC-lineage-traced animal models. We find that activation of medial VSMC proliferation occurs at low frequency after vascular injury and that only a subset of expanding clones migrate, which together drives formation of oligoclonal neointimal lesions. VSMC contribution in small atherosclerotic lesions is typically from one or two clones, similar to observations in mature lesions. Low frequency (<0.1%) of clonal VSMC proliferation is also observed in vitro. Single-cell RNA-sequencing revealed progressive cell state changes across a contiguous VSMC population at onset of injury-induced proliferation. Proliferating VSMCs mapped selectively to one of two distinct trajectories and were associated with cells showing extensive phenotypic switching. A proliferation-associated transitory state shared pronounced similarities with atypical SCA1+ VSMCs from uninjured mouse arteries and VSMCs in healthy human aorta. We show functionally that clonal expansion of SCA1+ VSMCs from healthy arteries occurs at higher rate and frequency compared with SCA1- cells.

CONCLUSION

Our data suggest that activation of proliferation at low frequency is a general, cell-intrinsic feature of VSMCs. We show that rare VSMCs in healthy arteries display VSMC phenotypic switching akin to that observed in pathological vessel remodelling and that this is a conserved feature of mouse and human healthy arteries. The increased proliferation of modulated VSMCs from healthy arteries suggests that these cells respond more readily to disease-inducing cues and could drive oligoclonal VSMC expansion.

Inflammatory Cell Dynamics after Murine Femoral Artery Wire Injury: A Multi-Parameter Flow Cytometry-Based Analysis

An acute inflammatory response following arterial surgery for atherosclerosis, such as balloon angioplasty, stenting, and surgical bypass, is an important driver of neointimal hyperplasia after arterial injury, which leads to recurrent ischemia. However, a comprehensive understanding of the dynamics of the inflammatory infiltrate in the remodeling artery is difficult to attain due to the shortcomings of conventional methods such as immunofluorescence. We developed a 15-parameter flow cytometry method to quantitate leukocytes and 13 leukocyte subtypes in murine arteries at 4 time points after femoral artery wire injury. Live leukocyte numbers peaked at 7 days, which preceded the peak neointimal hyperplasia lesion at 28 days. Neutrophils were the most abundant early infiltrate, followed by monocytes and macrophages. Eosinophils were elevated after 1 day, while natural killer and dendritic cells gradually infiltrated over the first 7 days; all decreased between 7 and 14 days. Lymphocytes began accumulating at 3 days and peaked at 7 days. Immunofluorescence of arterial sections demonstrated similar temporal trends of CD45+ and F4/80+ cells. This method allows for the simultaneous quantitation of multiple leukocyte subtypes from small tissue samples of injured murine arteries and identifies the CD64+Tim4+ macrophage phenotype as being potentially important in the first 7 days post-injury.

Correlation between stem cell molecular phenotype and atherosclerotic plaque neointima formation and analysis of stem cell signal pathways

Vascular stem cells exist in the three-layer structure of blood vessel walls and play an indispensable role in angiogenesis under physiological conditions and vascular remodeling under pathological conditions. Vascular stem cells are mostly quiescent, but can be activated in response to injury and participate in endothelial repair and neointima formation. Extensive studies have demonstrated the differentiation potential of stem/progenitor cells to repair endothelium and participate in neointima formation during vascular remodeling. The stem cell population has markers on the surface of the cells that can be used to identify this cell population. The main positive markers include Stem cell antigen-1 (Sca1), Sry-box transcription factor 10 (SOX10). Stromal cell antigen 1 (Stro-1) and Stem cell growth factor receptor kit (c-kit) are still controversial. Different parts of the vessel have different stem cell populations and multiple markers. In this review, we trace the role of vascular stem/progenitor cells in the progression of atherosclerosis and neointima formation, focusing on the expression of stem cell molecular markers that occur during neointima formation and vascular repair, as well as the molecular phenotypic changes that occur during differentiation of different stem cell types. To explore the correlation between stem cell molecular markers and atherosclerotic diseases and neointima formation, summarize the differential changes of molecular phenotype during the differentiation of stem cells into smooth muscle cells and endothelial cells, and further analyze the signaling pathways and molecular mechanisms of stem cells expressing different positive markers participating in intima formation and vascular repair. Summarizing the limitations of stem cells in the prevention and treatment of atherosclerotic diseases and the pressing issues that need to be addressed, we provide a feasible scheme for studying the signaling pathways of vascular stem cells involved in vascular diseases.

Beiging of perivascular adipose tissue regulates its inflammation and vascular remodeling

Although inflammation plays critical roles in the development of atherosclerosis, its regulatory mechanisms remain incompletely understood. Perivascular adipose tissue (PVAT) has been reported to undergo inflammatory changes in response to vascular injury. Here, we show that vascular injury induces the beiging (brown adipose tissue-like phenotype change) of PVAT, which fine-tunes inflammatory response and thus vascular remodeling as a protective mechanism. In a mouse model of endovascular injury, macrophages accumulate in PVAT, causing beiging phenotype change. Inhibition of PVAT beiging by genetically silencing PRDM16, a key regulator to beiging, exacerbates inflammation and vascular remodeling following injury. Conversely, activation of PVAT beiging attenuates inflammation and pathological vascular remodeling. Single-cell RNA sequencing reveals that beige adipocytes abundantly express neuregulin 4 (Nrg4) which critically regulate alternative macrophage activation. Importantly, significant beiging is observed in the diseased aortic PVAT in patients with acute aortic dissection. Taken together, vascular injury induces the beiging of adjacent PVAT with macrophage accumulation, where NRG4 secreted from the beige PVAT facilitates alternative activation of macrophages, leading to the resolution of vascular inflammation. Our study demonstrates the pivotal roles of PVAT in vascular inflammation and remodeling and will open a new avenue for treating atherosclerosis.

Perivascular adipose tissue (PVAT) has been reported to undergo inflammatory changes in response to vascular injury. Here, the authors show that vascular injury induces the beiging (brown adipose tissue-like phenotype change) of PVAT, which fine-tunes inflammatory response as a protective mechanism.

The Prostaglandin E2 Receptor EP4 Promotes Vascular Neointimal Hyperplasia through Translational Control of Tenascin C via the cAPM/PKA/mTORC1/rpS6 Pathway

Prostaglandin E2 (PGE2) is an important metabolite of arachidonic acid which plays a crucial role in vascular physiology and pathophysiology via its four receptors (EP1-4). However, the role of vascular smooth muscle cell (VSMC) EP4 in neointimal hyperplasia is largely unknown. Here we showed that VSMC-specific deletion of EP4 (VSMC-EP4) ameliorated, while VSMC-specific overexpression of human EP4 promoted, neointimal hyperplasia in mice subjected to femoral artery wire injury or carotid artery ligation. In vitro studies revealed that pharmacological activation of EP4 promoted, whereas inhibition of EP4 suppressed, proliferation and migration of primary-cultured VSMCs. Mechanically, EP4 significantly increased the protein expression of tenascin C (TN-C), a pro-proliferative and pro-migratory extracellular matrix protein, at the translational level. Knockdown of TN-C markedly suppressed EP4 agonist-induced VSMC proliferation and migration. Further studies uncovered that EP4 upregulated TN-C protein expression via the PKA/mTORC1/Ribosomal protein S6 (rpS6) pathway. Together, our findings demonstrate that VSMC EP4 increases TN-C protein expression to promote neointimal hyperplasia via the PKA-mTORC1-rpS6 pathway. Therefore, VSMC EP4 may represent a potential therapeutic target for vascular restenosis.

A machine learning pipeline revealing heterogeneous responses to drug perturbations on vascular smooth muscle cell spheroid morphology and formation

Machine learning approaches have shown great promise in biology and medicine discovering hidden information to further understand complex biological and pathological processes. In this study, we developed a deep learning-based machine learning algorithm to meaningfully process image data and facilitate studies in vascular biology and pathology. Vascular injury and atherosclerosis are characterized by neointima formation caused by the aberrant accumulation and proliferation of vascular smooth muscle cells (VSMCs) within the vessel wall. Understanding how to control VSMC behaviors would promote the development of therapeutic targets to treat vascular diseases. However, the response to drug treatments among VSMCs with the same diseased vascular condition is often heterogeneous. Here, to identify the heterogeneous responses of drug treatments, we created an in vitro experimental model system using VSMC spheroids and developed a machine learning-based computational method called HETEROID (heterogeneous spheroid). First, we established a VSMC spheroid model that mimics neointima-like formation and the structure of arteries. Then, to identify the morphological subpopulations of drug-treated VSMC spheroids, we used a machine learning framework that combines deep learning-based spheroid segmentation and morphological clustering analysis. Our machine learning approach successfully showed that FAK, Rac, Rho, and Cdc42 inhibitors differentially affect spheroid morphology, suggesting that multiple drug responses of VSMC spheroid formation exist. Overall, our HETEROID pipeline enables detailed quantitative drug characterization of morphological changes in neointima formation, that occurs in vivo, by single-spheroid analysis.

Salt-Inducible Kinase 3 Promotes Vascular Smooth Muscle Cell Proliferation and Arterial Restenosis by Regulating AKT and PKA-CREB Signaling

Objective

Arterial restenosis is the pathological narrowing of arteries after endovascular procedures, and it is an adverse event that causes patients to experience recurrent occlusive symptoms. Following angioplasty, vascular smooth muscle cells (SMCs) change their phenotype, migrate, and proliferate, resulting in neointima formation, a hallmark of arterial restenosis. SIKs (salt-inducible kinases) are a subfamily of the AMP-activated protein kinase family that play a critical role in metabolic diseases including hepatic lipogenesis and glucose metabolism. Their role in vascular pathological remodeling, however, has not been explored. In this study, we aimed to understand the role and regulation of SIK3 in vascular SMC migration, proliferation, and neointima formation.

Approach and Results

We observed that SIK3 expression was low in contractile aortic SMCs but high in proliferating SMCs. It was also highly induced by growth medium in vitro and in neointimal lesions in vivo. Inactivation of SIKs significantly attenuated vascular SMC proliferation and up-regulated p21CIP1 and p27KIP1. SIK inhibition also suppressed SMC migration and modulated actin polymerization. Importantly, we found that inhibition of SIKs reduced neointima formation and vascular inflammation in a femoral artery wire injury model. In mechanistic studies, we demonstrated that inactivation of SIKs mainly suppressed SMC proliferation by down-regulating AKT (protein kinase B) and PKA (protein kinase A)-CREB (cAMP response element-binding protein) signaling. CRTC3 (CREB-regulated transcriptional coactivator 3) signaling likely contributed to SIK inactivation-mediated antiproliferative effects.

Conclusions

These findings suggest that SIK3 may play a critical role in regulating SMC proliferation, migration, and arterial restenosis. This study provides insights into SIK inhibition as a potential therapeutic strategy for treating restenosis in patients with peripheral arterial disease.

TET2 Protects Against Vascular Smooth Muscle Cell Apoptosis and Intimal Thickening in Transplant Vasculopathy

BACKGROUND

Coronary allograft vasculopathy (CAV) is a devastating sequela of heart transplant in which arterial intimal thickening limits coronary blood flow. There are currently no targeted therapies to prevent or reduce this pathology that leads to transplant failure. Vascular smooth muscle cell (VSMC) phenotypic plasticity is critical in CAV neointima formation. TET2 (TET methylcytosine dioxygenase 2) is an important epigenetic regulator of VSMC phenotype, but the role of TET2 in the progression of CAV is unknown.

METHODS

We assessed TET2 expression and activity in human CAV and renal transplant samples. We also used the sex-mismatched murine aortic graft model of graft arteriopathy (GA) in wild-type and inducible smooth muscle-specific Tet2 knockout mice; and in vitro studies in murine and human VSMCs using knockdown, overexpression, and transcriptomic approaches to assess the role of TET2 in VSMC responses to IFNγ (interferon γ), a cytokine elaborated by T cells that drives CAV progression.

RESULTS

In the present study, we found that TET2 expression and activity are negatively regulated in human CAV and renal transplant samples and in the murine aortic graft model of GA. IFNγ was sufficient to repress TET2 and induce an activated VSMC phenotype in vitro. TET2 depletion mimicked the effects of IFNγ, and TET2 overexpression rescued IFNγ-induced dedifferentiation. VSMC-specific TET2 depletion in aortic grafts, and in the femoral wire restenosis model, resulted in increased VSMC apoptosis and medial thinning. In GA, this apoptosis was tightly correlated with proliferation. In vitro, TET2-deficient VSMCs undergo apoptosis more readily in response to IFNγ and expressed a signature of increased susceptibility to extrinsic apoptotic signaling. Enhancing TET2 enzymatic activity with high-dose ascorbic acid rescued the effect of GA-induced VSMC apoptosis and intimal thickening in a TET2-dependent manner.

CONCLUSIONS

TET2 is repressed in CAV and GA, likely mediated by IFNγ. TET2 serves to protect VSMCs from apoptosis in the context of transplant vasculopathy or IFNγ stimulation. Promoting TET2 activity in vivo with systemic ascorbic acid reduces VSMC apoptosis and intimal thickening. These data suggest that promoting TET2 activity in CAV may be an effective strategy for limiting CAV progression.

Aralia armata (Wall.) Seem Improves Intimal Hyperplasia after Vascular Injury by Downregulating the Wnt3α/Dvl-1/β-Catenin Pathway

The aim of the study is to examine the mechanism of Aralia armata (Wall.) Seem (AAS) in improving intimal hyperplasia after vascular injury in rats. Rats with femoral artery injury were randomly divided into three groups: the model group, AAS low-dose group (40 mg/kg), and AAS high-dose group (80 mg/kg). The sham operation group was used as a control group. HE staining was used to observe the changes in femoral artery vessels. Immunohistochemistry was adopted to detect α-SMA, PCNA, GSK-3β, and β-catenin proteins in femoral artery tissue. The CCK-8 test and wound healing assay were employed to analyze the effect of AAS on proliferation and migration of vascular smooth muscle cells (VSMCs) cultured in vitro. Western blotting (WB) and polymerase chain reaction (PCR) assays were used to evaluate the molecular mechanism. AAS reduced the stenosis of blood vessels and the protein expressions of α-SMA, PCNA, GSK-3β, and β-catenin compared to the model group. In addition, AAS (0-15 μg/mL) effectively inhibited the proliferation and migration of VSMCs. Moreover, the results of WB and PCR showed that AAS could inhibit the activation of β-catenin induced by 15% FBS and significantly decrease the expression levels of Wnt3α, Dvl-1, GSK-3β, β-catenin, and cyclin D1 in the upstream and downstream of the pathway. AAS could effectively inhibit the proliferation and migration of neointima after vascular injury in rats by regulating the Wnt/β-catenin signaling pathway.

Sirt7 Deficiency Attenuates Neointimal Formation Following Vascular Injury by Modulating Vascular Smooth Muscle Cell Proliferation

BACKGROUND

Sirt7 is a recently identified sirtuin and has important roles in various pathological conditions, including cancer progression and metabolic disorders. It has previously been reported that Sirt7 is a key molecule in acute myocardial wound healing and pressure overload-induced cardiac hypertrophy. In this study, the role of Sirt7 in neointimal formation after vascular injury is investigated.Methods and Results:Systemic (Sirt7^-/-) and smooth muscle cell-specific Sirt7-deficient mice were subjected to femoral artery wire injury. Primary vascular smooth muscle cells (VSMCs) were isolated from the aorta of wild type (WT) and Sirt7^-/-mice and their capacity for cell proliferation and migration was compared. Sirt7 expression was increased in vascular tissue at the sites of injury. Sirt7^-/-mice demonstrated significant reduction in neointimal formation compared to WT mice. In vitro, Sirt7 deficiency attenuated the proliferation of serum-induced VSMCs. Serum stimulation-induced upregulation of cyclins and cyclin-dependent-kinase 2 (CDK2) was significantly attenuated in VSMCs of Sirt7^-/-compared with WT mice. These changes were accompanied by enhanced expression of the microRNA 290-295 cluster, the translational negative regulator of CDK2, in VSMCs of Sirt7^-/-mice. It was confirmed that smooth muscle cell-specific Sirt7-deficient mice showed significant reduction in neointima compared with control mice.

CONCLUSIONS

Sirt7 deficiency attenuates neointimal formation after vascular injury. Given the predominant role in vascular neointimal formation, Sirt7 is a potentially suitable target for treatment of vascular diseases.

Roles of Epicardial Adipose Tissue in the Pathogenesis of Coronary Atherosclerosis - An Update on Recent Findings

Adipose tissue serves not only as an energy store or a mechanical cushion, but also as an endocrine organ. Recent evidence revealed that perivascular adipose tissue is involved in vascular homeostasis and pathophysiology of adjacent arteries by producing various adipokines. Epicardial adipose tissue (EAT) is located between the surface of the heart and the visceral layer of the pericardium and surrounds the coronary arteries. Many clinical studies suggest that an increase in EAT volume is associated with coronary artery disease. It has been reported that exercise and some antidiabetic drugs can reduce EAT volume. In this review, we outline recent findings on the roles of EAT in the pathogenesis of coronary atherosclerosis.

The antiplatelet agent revacept prevents the increase of systemic thromboxane A2 biosynthesis and neointima hyperplasia

Neointima hyperplasia is a crucial component of restenosis after coronary angioplasty. We have hypothesized that enhanced generation of platelet-derived thromboxane (TX)A₂ in response to vascular damage plays a critical role in neointimal hyperplasia and that antiplatelet agents may mitigate it. In cocultures of human platelets and coronary artery smooth muscle cells (CASMC), we found that platelets induced morphologic changes and enhanced the migration of CASMC. The exposure of platelets to Aspirin [an inhibitor of cyclooxygenase (COX)-1] reduced the generation of TXA₂ and prevented the morphological and functional changes induced by platelets in CASMC. Platelet-derived TXA₂ induced COX-2 and enhanced prostaglandin (PG)E₂ biosynthesis in CASMC, a known mechanism promoting neointimal hyperplasia. COX-2 induction was prevented by different antiplatelet agents, i.e., Aspirin, the TP antagonist SQ29,548, or Revacept (a dimeric soluble GPVI-Fc fusion protein). The administration of the novel antiplatelet agent Revacept to C57BL/6 mice, beginning three days before femoral artery denudation, and continuing up to seven days after injury, prevented the increase of the systemic biosynthesis di TXA₂ and reduced femoral artery intima-to-media area and the levels of markers of cell proliferation and macrophage infiltration. Revacept might serve as a therapeutic agent for percutaneous coronary angioplasty and stent implantation.

miR-214-3p-Sufu-GLI1 is a novel regulatory axis controlling inflammatory smooth muscle cell differentiation from stem cells and neointimal hyperplasia

Background

Inflammatory smooth muscle cells (iSMCs) generated from adventitial stem/progenitor cells (AdSPCs) have been recognised as a new player in cardiovascular disease, and microRNA-214-3p (miR-214-3p) has been implicated in mature vascular SMC functions and neointimal hyperplasia. Here, we attempted to elucidate the functional involvements of miR-214-3p in iSMC differentiation from AdSPCs and unravel the therapeutic potential of miR-214-3p signalling in AdSPCs for injury-induced neointimal hyperplasia.

Methods

The role of miR-214-3p in iSMC differentiation from AdSPCs was evaluated by multiple biochemistry assays. The target of miR-214-3p was identified through binding site mutation and reporter activity analysis. A murine model of injury-induced arterial remodelling and stem cell transplantation was conducted to study the therapeutic potential of miR-214-3p. RT-qPCR analysis was performed to examine the gene expression in healthy and diseased human arteries.

Results

miR-214-3p prevented iSMC differentiation/generation from AdSPCs by restoring sonic hedgehog-glioma-associated oncogene 1 (Shh-GLI1) signalling. Suppressor of fused (Sufu) was identified as a functional target of miR-214-3p during iSMC generation from AdSPCs. Mechanistic studies revealed that miR-214-3p over-expression or Sufu inhibition can promote nuclear accumulation of GLI1 protein in AdSPCs, and the consensus sequence (GACCACCCA) for GLI1 binding within smooth muscle alpha-actin (SMαA) and serum response factor (SRF) gene promoters is required for their respective regulation by miR-214-3p and Sufu. Additionally, Sufu upregulates multiple inflammatory gene expression (IFNγ, IL-6, MCP-1 and S100A4) in iSMCs. In vivo, transfection of miR-214-3p into the injured vessels resulted in the decreased expression level of Sufu, reduced iSMC generation and inhibited neointimal hyperplasia. Importantly, perivascular transplantation of AdSPCs increased neointimal hyperplasia, whereas transplantation of AdSPCs over-expressing miR-214-3p prevented this. Finally, decreased expression of miR-214-3p but increased expression of Sufu was observed in diseased human arteries.

Conclusions

We present a previously unexplored role for miR-214-3p in iSMC differentiation and neointima iSMC hyperplasia and provide new insights into the therapeutic effects of miR-214-3p in vascular disease.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s13287-020-01989-w.

Corilagin Ameliorates Atherosclerosis in Peripheral Artery Disease via the Toll-Like Receptor-4 Signaling Pathway in vitro and in vivo

We investigated if corilagin can ameliorate or reverse atherosclerotic development via the toll-like receptor 4 (TLR4) signaling pathway in vitro and in vivo. Ana-1 cells or mouse peritoneal macrophages (MPMs) were stimulated with oxidized low-density lipoprotein followed by corilagin treatment. TLR4 expression in Ana-1 cells was upregulated by lentiviral transduction and downregulated by small interfering RNA. Peripheral blood mononuclear cells (PBMCs), plasma samples, and femoral arteries were collected from rats exhibiting peripheral artery disease (PAD). mRNA and protein expression of TLR4 and downstream molecules were decreased significantly by corilagin treatment in Ana-1 cells, MPMs, and rat PBMCs, and the reduction remained irrespective of downregulation or upregulation of TLR4 expression in Ana-1 cells. Corilagin also exerted a prominent effect on changes in plasma levels of cytokines and the pathologic manifestation of atherosclerosis in femoral arteries. Corilagin could ameliorate the development of atherosclerotic plaques by inhibiting the TLR4 signaling pathway in monocyte/macrophages and reduce the release of proinflammatory cytokines. This study provides a new therapeutic target and new niche targeting drug to oppose atherosclerosis and reveals the enormous potential of corilagin for control of PAD in humans.

Macrophage NCOR1 Deficiency Ameliorates Myocardial Infarction and Neointimal Hyperplasia in Mice

Background

NCOR1 (nuclear receptor corepressor 1) is an essential coregulator of gene transcription. It has been shown that NCOR1 in macrophages plays important roles in metabolic regulation. However, the function of macrophage NCOR1 in response to myocardial infarction (MI) or vascular wire injury has not been elucidated.

Methods and Results

Here, using macrophage Ncor1 knockout mouse in combination with a mouse model of MI, we demonstrated that macrophage NCOR1 deficiency significantly reduced infarct size and improved cardiac function after MI. In addition, macrophage NCOR1 deficiency markedly inhibited neointimal hyperplasia and vascular remodeling in a mouse model of arterial wire injury. Inflammation and macrophage proliferation were substantially attenuated in hearts and arteries of macrophage Ncor1 knockout mice after MI and arterial wire injury, respectively. Cultured primary macrophages from macrophage Ncor1 knockout mice manifested lower expression of inflammatory genes upon stimulation by interleukin‐1β, interleukin‐6, or lipopolysaccharide, together with much less activation of inflammatory signaling cascades including signal transducer and activator of transcription 1 and nuclear factor‐κB. Furthermore, macrophage Ncor1 knockout macrophages were much less proliferative in culture, with inhibited cell cycle progression compared with control cells.

Conclusions

Collectively, our data have demonstrated that NCOR1 is a critical regulator of macrophage inflammation and proliferation and that deficiency of NCOR1 in macrophages attenuates MI and neointimal hyperplasia. Therefore, macrophage NCOR1 may serve as a potential therapeutic target for MI and restenosis.

Microbe-Derived Butyrate and Its Receptor, Free Fatty Acid Receptor 3, But Not Free Fatty Acid Receptor 2, Mitigate Neointimal Hyperplasia Susceptibility After Arterial Injury

Background

Arterial restenosis after vascular surgery is a common cause of midterm restenosis and treatment failure. Herein, we aim to investigate the role of microbe‐derived butyrate, FFAR2 (free fatty acid receptor 2), and FFAR3 (free fatty acid receptor 3) in mitigating neointimal hyperplasia development in remodeling murine arteries after injury.

Methods and Results

C57BL/6 mice treated with oral vancomycin before unilateral femoral wire injury to deplete gut microbiota had significantly diminished serum and stool butyrate and more neointimal hyperplasia development after arterial injury, which was reversed by concomitant butyrate supplementation. Deficiency of FFAR3 but not FFAR2, both receptors for butyrate, exacerbated neointimal hyperplasia development after injury. FFAR3 deficiency was also associated with delayed recovery of the endothelial layer in vivo. FFAR3 gene expression was observed in multiple peripheral arteries, and expression was increased after arterial injury. Treatment of endothelial but not vascular smooth muscle cells with the pharmacologic FFAR3 agonist 1‐methylcyclopropane carboxylate stimulated cellular migration and proliferation in scratch assays.

Conclusions

Our results support a protective role for butyrate and FFAR3 in the development of neointimal hyperplasia after arterial injury and delineate activation of the butyrate‐FFAR3 pathway as a valuable strategy for the prevention and treatment of neointimal hyperplasia.

Corylin Inhibits Vascular Cell Inflammation, Proliferation and Migration and Reduces Atherosclerosis in ApoE-Deficient Mice

Atherosclerosis is a complex disease that includes several events, including reactive oxygen species (ROS) stress, inflammation, endothelial dysfunction, lipid deposition, and vascular smooth muscle cell (VSMC) proliferation and migration, which result in atherosclerotic plaque formation. Corylin, a flavonoid compound, is known to exhibit antioxidative, anti-inflammatory and antiproliferative effects. However, it remains unknown whether corylin could modulate atherogenesis. Here, we identified the anti-inflammatory effect of corylin in tumor necrosis factor-α (TNF-α)-induced vascular cells. In human umbilical vein endothelial cells (HUVECs), corylin suppressed TNF-α-induced monocyte adhesion to the HUVECs and transmigration by downregulating the ROS/JNK/nuclear factor-kappa beta (NF-κB) p65 pathway. In VSMCs, corylin inhibited TNF-α-induced monocyte adhesion by suppressing ROS production, mitogen-activated protein kinase (MAPK) phosphorylation and NF-κB p65 translocation. In platelet-derived growth factor-BB (PDGF-BB)-induced VSMCs, corylin inhibited PDGF-BB-induced VSMC proliferation and migration through regulating the mammalian target of rapamycin (mTOR)/dynamin-1-like protein 1 (Drp1) signaling cascade. In addition, corylin treatment not only attenuated atherosclerotic lesions, ROS production, vascular cell adhesion protein-1 (VCAM-1) expression, monocyte adhesion and VSMC proliferation in apolipoprotein E (ApoE)-deficient mice but also inhibited neointimal hyperplasia in endothelial-denuded mice. Thus, corylin may be a potential prevention and treatment for atherosclerosis.

TEAD1 (TEA Domain Transcription Factor 1) Promotes Smooth Muscle Cell Proliferation Through Upregulating SLC1A5 (Solute Carrier Family 1 Member 5)-Mediated Glutamine Uptake

Supplemental Digital Content is available in the text.

Rationale:

TEAD (TEA domain transcription factor) 1—a major effector of the Hippo signaling pathway—acts as an oncoprotein in a variety of tumors. However, the function of TEAD1 in vascular smooth muscle cells (VSMCs) remains unclear.

Objective:

To assess the role of TEAD1 in vascular injury–induced smooth muscle proliferation and delineate the mechanisms underlying its action.

Methods and Results:

We found that TEAD1 expression is enhanced in mouse femoral artery after wire injury and correlates with the activation of mTORC1 (mechanistic target of rapamycin complex 1) signaling in vivo. Using an inducible smooth muscle–specific Tead1 KO (knockout) mouse model, we found that specific deletion of Tead1 in adult VSMCs is sufficient to attenuate arterial injury–induced neointima formation due to inhibition of mTORC1 activation and VSMC proliferation. Furthermore, we found that TEAD1 plays a unique role in VSMCs, where it not only downregulates VSMC differentiation markers but also activates mTORC1 signaling, leading to enhanced VSMC proliferation. Using whole-transcriptome sequencing analysis, we identified Slc1a5 (solute carrier family 1 member 5)—a key glutamine transporter—as a novel TEAD1 target gene. SLC1A5 overexpression mimicked TEAD1 in promoting mTORC1 activation and VSMC proliferation. Moreover, depletion of SLC1A5 by silencing RNA or blocking SLC1A5-mediated glutamine uptake attenuated TEAD1-dependent mTORC1 activation and VSMC proliferation.

Conclusions:

Our study unravels a novel mechanism by which TEAD1 promotes VSMC proliferation via transcriptional induction of SLC1A5, thereby activating mTORC1 signaling and promoting neointima formation.

C-reactive protein derived from perivascular adipose tissue accelerates injury-induced neointimal hyperplasia

AIM

Inflammation within the perivascular adipose tissue (PVAT) in obesity plays an important role in cardiovascular disorders. C-reactive protein (CRP) level in obesity patients is significantly increased and associated with the occurrence and progression of cardiovascular disease. We tested the hypothesis CRP derived from PVAT in obesity contributes to vascular remodeling after injury.

METHODS

A high-fat diet (HFD) significantly increased CRP expression in PVAT. We transplanted thoracic aortic PVAT from wild-type (WT) or transgenic CRP-expressing (CRPTG) mice to the injured femoral artery in WT mice.

RESULTS

At 4 weeks after femoral artery injury, the neointimal/media ratio was increased significantly in WT mice that received PVAT from CRPTG mice compared with that in WT mice that received WT PVAT. Transplanted CRPTG PVAT also significantly accelerated adventitial macrophage infiltration and vasa vasorum proliferation. It was revealed greater macrophage infiltration in CRPTG adipose tissue than in WT adipose tissue and CRP significantly increased the adhesion rate of monocytes through receptor Fcγ RI. Proteome profiling showed CRP over-expression promoted the expression of chemokine (C-X-C motif) ligand 7 (CXCL7) in adipose tissue, transwell assay showed CRP increased monocyte migration indirectly via the induction of CXCL7 expression in adipocytes.

CONCLUSION

CRP derived from PVAT was significantly increased in HFD mice and promoted neointimal hyperplasia after vascular injury.

Novel Paracrine Functions of Smooth Muscle Cells in Supporting Endothelial Regeneration Following Arterial Injury

RATIONALE

Regeneration of denuded or injured endothelium is an important component of vascular injury response. Cell-cell communication between endothelial cells and smooth muscle cells (SMCs) plays a critical role not only in vascular homeostasis but also in disease. We have previously demonstrated that PKCδ (protein kinase C-delta) regulates multiple components of vascular injury response including apoptosis of SMCs and production of chemokines, thus is an attractive candidate for a role in SMC-endothelial cells communication.

OBJECTIVE

To test whether PKCδ-mediated paracrine functions of SMCs influence reendothelialization in rodent models of arterial injury.

METHODS AND RESULTS

Femoral artery wire injury was performed in SMC-conditional Prkcd knockout mice, and carotid angioplasty was conducted in rats receiving transient Prkcd knockdown or overexpression. SMC-specific knockout of Prkcd impaired reendothelialization, reflected by a smaller Evans blue-excluding area in the knockout compared with the wild-type controls. A similar impediment to reendothelialization was observed in rats with SMC-specific knockdown of Prkcd. In contrast, SMC-specific gene transfer of Prkcd accelerated reendothelialization. In vitro, medium conditioned by AdPKCδ-infected SMCs increased endothelial wound closure without affecting their proliferation. A polymerase chain reaction-based array analysis identified Cxcl1 and Cxcl7 among others as PKCδ-mediated chemokines produced by SMCs. Mechanistically, we postulated that PKCδ regulates Cxcl7 expression through STAT3 (signal transducer and activator of transcription 3) as knockdown of STAT3 abolished Cxcl7 expression. The role of CXCL7 in SMC-endothelial cells communication was demonstrated by blocking CXCL7 or its receptor CXCR2, both significantly inhibited endothelial wound closure. Furthermore, insertion of a Cxcl7 cDNA in the lentiviral vector that carries a Prkcd shRNA overcame the adverse effects of Prkcd knockdown on reendothelialization.

CONCLUSIONS

SMCs promote reendothelialization in a PKCδ-dependent paracrine mechanism, likely through CXCL7-mediated recruitment of endothelial cells from uninjured endothelium.

Luseogliflozin attenuates neointimal hyperplasia after wire injury in high-fat diet-fed mice via inhibition of perivascular adipose tissue remodeling

BACKGROUND

Excess fat deposition could induce phenotypic changes of perivascular adipose tissue (PVAT remodeling), which may promote the progression of atherosclerosis via modulation of adipocytokine secretion. However, it remains unclear whether and how suppression of PVAT remodeling could attenuate vascular injury. In this study, we examined the effect of sodium-glucose cotransporter 2 (SGLT2) inhibitor, luseogliflozin on PVAT remodeling and neointima formation after wire injury in mice.

METHODS

Wilt-type mice fed with low-fat diet (LFD) or high-fat diet (HFD) received oral administration of luseogliflozin (18 mg/kg/day) or vehicle. Mice underwent bilateral femoral artery wire injury followed by unilateral removal of surrounding PVAT. After 25 days, injured femoral arteries and surrounding PVAT were analyzed.

RESULTS

In LFD-fed lean mice, neither luseogliflozin treatment or PVAT removal attenuated the intima-to-media (I/M) ratio of injured arteries. However, in HFD-fed mice, luseogliflozin or PVAT removal reduced the I/M ratio, whereas their combination showed no additive reduction. In PVAT surrounding injured femoral arteries of HFD-fed mice, luseogliflozin treatment decreased the adipocyte sizes. Furthermore, luseogliflozin reduced accumulation of macrophages expressing platelet-derived growth factor-B (PDGF-B) and increased adiponectin gene expression. Gene expression levels of Pdgf-b in PVAT were correlated with the I/M ratio.

CONCLUSIONS

Our present study suggests that luseogliflozin could attenuate neointimal hyperplasia after wire injury in HFD-fed mice partly via suppression of macrophage PDGF-B expression in PVAT. Inhibition of PVAT remodeling by luseogliflozin may be a novel therapeutic target for vascular remodeling after angioplasty.

Mitochondrial Protein Poldip2 (Polymerase Delta Interacting Protein 2) Controls Vascular Smooth Muscle Differentiated Phenotype by O-Linked GlcNAc (N-Acetylglucosamine) Transferase-Dependent Inhibition of a Ubiquitin Proteasome System

RATIONALE

The mitochondrial Poldip2 (protein polymerase interacting protein 2) is required for the activity of the tricarboxylic acid cycle. As a consequence, Poldip2 deficiency induces metabolic reprograming with repressed mitochondrial respiration and increased glycolytic activity. Though homozygous deletion of Poldip2 is lethal, heterozygous mice are viable and show protection against aneurysm and injury-induced neointimal hyperplasia, diseases linked to loss of vascular smooth muscle differentiation. Thus, we hypothesize that the metabolic reprograming induced by Poldip2 deficiency controls VSMC differentiation.

OBJECTIVE

To determine the role of Poldip2-mediated metabolic reprograming in phenotypic modulation of VSMC.

METHODS AND RESULTS

We show that Poldip2 deficiency in vascular smooth muscle in vitro and in vivo induces the expression of the SRF (serum response factor), myocardin, and MRTFA (myocardin-related transcription factor A) and dramatically represses KLF4 (Krüppel-like factor 4). Consequently, Poldip2-deficient VSMC and mouse aorta express high levels of contractile proteins and, more significantly, these cells do not dedifferentiate nor acquire macrophage-like characteristics when exposed to cholesterol or PDGF (platelet-derived growth factor). Regarding the mechanism, we found that Poldip2 deficiency upregulates the hexosamine biosynthetic pathway and OGT (O-linked N-acetylglucosamine transferase)-mediated protein O-GlcNAcylation. Increased protein glycosylation causes the inhibition of a nuclear ubiquitin proteasome system responsible for SRF stabilization and KLF4 repression and is required for the establishment of the differentiated phenotype in Poldip2-deficient cells.

CONCLUSIONS

Our data show that Poldip2 deficiency induces a highly differentiated phenotype in VSMCs through a mechanism that involves regulation of metabolism and proteostasis. Additionally, our study positions mitochondria-initiated signaling as key element of the VSMC differentiation programs that can be targeted to modulate VSMC phenotype during vascular diseases.

Tumor Necrosis Factor Receptor-Associated Factor 5 Promotes Arterial Neointima Formation through Smooth Muscle Cell Proliferation

Tumor necrosis factor (TNF) receptor-associated factors (TRAFs) are cytoplasmic adaptor proteins of the TNF/interleukin (IL)-1/Toll-like receptor superfamily. Ligands of this family such as TNFα, CD40L, and IL-1β promote chronic inflammatory processes such as atherosclerosis and restenosis, the latter being a common adverse reaction after vascular interventions. We previously reported overexpression of TRAF5 in murine and human atheromata and TRAF5-dependent proinflammatory functions in vitro. However, the role of TRAF5 in restenosis remains unsettled. To evaluate whether TRAF5 affects neointima formation, TRAF5-/-LDLR-/- and TRAF5+/+LDLR-/- mice consuming a high cholesterol diet (HCD) received wire-induced injury of the carotid artery. After 28 days, TRAF5-deficient mice showed a 45% decrease in neointimal area formation compared with TRAF5-compentent mice. Furthermore, neointimal vascular smooth muscle cells (vSMC) and macrophages decreased whereas collagen increased in TRAF5-deficient mice. Mechanistically, the latter expressed lower transcript levels of the matrix metalloproteinases 2 and 9, both instrumental in extracellular matrix degradation and vSMC mobilization. Additionally, TRAF5-specific siRNA interference rendered murine vSMC less proliferative upon CD40L stimulation. In accordance with these findings, fewer vSMC isolated from TRAF5-deficient aortas were in a proliferative state as assessed by Ki67 and cyclin B1 expression. In conclusion, TRAF5 deficiency mitigates neointima formation in mice, likely through a TRAF5-dependent decrease in vSMC proliferation.

Development of gene therapy with a cyclic adenosine monophosphate response element decoy oligodeoxynucleotide to prevent vascular intimal hyperplasia

OBJECTIVE

Intimal hyperplasia (IH) is the main cause of therapeutic failure after vascular and endovascular surgery. However, there is currently no targeted therapy for the treatment of IH. We recently reported that the inhibition of cyclic adenosine monophosphate response element (CRE) binding protein (CREB) activation is important in vein graft IH. We focused on a decoy oligodeoxynucleotide (ODN) therapeutic strategy for suppressing IH as a clinical application. The objective of this study was to confirm the therapeutic effect of a CRE decoy ODN in an animal model as a novel therapy for preventing intimal hyperplasia as the first step of the preclinical study of our strategy.

METHODS

We designed two phosphorothioate CREs and two scramble decoy ODNs and screened them using a CREB transcription assay to check their ability to bind to a CRE sequence. We chose a CRE decoy ODN with high first-binding ability and transfected it into vascular smooth muscle cells (VSMCs) in vitro. Proliferation and migration were assessed using MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assays and modified Boyden chamber assays. We examined CRE activity using a luciferase reporter gene assay. We assessed the expression of messenger RNAs by quantitative real-time polymerase chain reaction. In a wire-injury mouse model (C57BL6, n = 6), CRE decoy ODN was transfected into the injured vessel wall using an ultrasound-sonoporation method in vivo. Mitogen-activated protein kinase-activated protein kinase 3 (MAPKAPK3) and four and a half LIM domains 5 (FHL5) expression of pregrafting vein remnants were assessed by immunohistologic analyses.

RESULTS

Compared with scramble decoy ODN, the selected CRE decoy ODN could significantly decrease CRE activity (mean ± standard error of the mean: 0.20 ± 0.03 vs 1.00 ± 0.16, n = 6; P < .05) as shown by a luciferase reporter gene assay, VSMC proliferation (0.73 ± 0.04 vs 0.89 ± 0.02, n = 6; P < .05) and migration (96.4 ± 6.1 vs 311.4 ± 19.1 migrated VSMCs/well, n = 6; P < .05) after 24-hour transfection. The CRE decoy ODN significantly suppressed the formation of IH at injured vessel walls in an animal model, as analyzed by pathologic staining (0.20 ± 0.02 vs 0.56 ± 0.08, area of the intima/area of the artery vs the control after 21 days' transfection, n = 6; P < .05). Furthermore, MAPKAPK3 and FHL5, which are CREB activators, were significantly expressed in pregrafting vein remnants in diabetes mellitus patients.

CONCLUSIONS

CREB-CRE signaling is an important mechanism of IH formation, and CRE decoy therapy can help preventing IH. This study is the first part of the preclinical study of our strategy.

Nuclear Focal Adhesion Kinase Controls Vascular Smooth Muscle Cell Proliferation and Neointimal Hyperplasia Through GATA4-Mediated Cyclin D1 Transcription

RATIONALE

Neointimal hyperplasia is characterized by excessive accumulation of vascular smooth muscle cells (SMCs) leading to occlusive disorders, such as atherosclerosis and stenosis. Blood vessel injury increases growth factor secretion and matrix synthesis, which promotes SMC proliferation and neointimal hyperplasia via FAK (focal adhesion kinase).

OBJECTIVE

To understand the mechanism of FAK action in SMC proliferation and neointimal hyperplasia.

METHODS AND RESULTS

Using combined pharmacological FAK catalytic inhibition (VS-4718) and SMC-specific FAK kinase-dead (Myh11-Cre-ER^T2) mouse models, we report that FAK regulates SMC proliferation and neointimal hyperplasia in part by governing GATA4- (GATA-binding protein 4) cyclin D1 signaling. Inhibition of FAK catalytic activity facilitates FAK nuclear localization, which is required for proteasome-mediated GATA4 degradation in the cytoplasm. Chromatin immunoprecipitation identified GATA4 binding to the mouse cyclin D1 promoter, and loss of GATA4-mediated cyclin D1 transcription diminished SMC proliferation. Stimulation with platelet-derived growth factor or serum activated FAK and redistributed FAK from the nucleus to cytoplasm, leading to concomitant increase in GATA4 protein and cyclin D1 expression. In a femoral artery wire injury model, increased neointimal hyperplasia was observed in parallel with elevated FAK activity, GATA4 and cyclin D1 expression following injury in control mice, but not in VS-4718-treated and SMC-specific FAK kinase-dead mice. Finally, lentiviral shGATA4 knockdown in the wire injury significantly reduced cyclin D1 expression, SMC proliferation, and neointimal hyperplasia compared with control mice.

CONCLUSIONS

Nuclear enrichment of FAK by inhibition of FAK catalytic activity during vessel injury blocks SMC proliferation and neointimal hyperplasia through regulation of GATA4-mediated cyclin D1 transcription.

Nesfatin-1 suppresses peripheral arterial remodeling without elevating blood pressure in mice

Nesfatin-1 is a novel anorexic peptide hormone that also exerts cardiovascular protective effects in rodent models. However, nesfatin-1 treatment at high doses also exerts vasopressor effects, which potentially limits its therapeutic application. Here, we evaluated the vasoprotective and vasopressor effects of nesfatin-1 at different doses in mouse models. Wild-type mice and those with the transgene nucleobindin-2, a precursor of nesfatin-1, were employed. Wild-type mice were randomly assigned to treatment with vehicle or nesfatin-1 at 0.2, 2.0 or 10 μg/kg/day (Nes-0.2, Nes-2, Nes-10, respectively). Subsequently, mice underwent femoral artery wire injury to induce arterial remodeling. After 4 weeks, injured arteries were collected for morphometric analysis. Compared with vehicle, nesfatin-1 treatments at 2.0 and 10 μg/kg/day decreased body weights and elevated plasma nesfatin-1 levels with no changes in systolic blood pressure. Furthermore, these treatments reduced neointimal hyperplasia without inducing undesirable remodeling in injured arteries. However, nesfatin-1 treatment at 0.2 μg/kg/day was insufficient to elevate plasma nesfatin-1 levels and showed no vascular effects. In nucleobindin-2-transgenic mice, blood pressure was slightly higher but neointimal area was lower than those observed in littermate controls. In cultured human vascular endothelial cells, nesfatin-1 concentration-dependently increased nitric oxide production. Additionally, nesfatin-1 increased AMP-activated protein kinase phosphorylation, which was abolished by inhibiting liver kinase B1. We thus demonstrated that nesfatin-1 treatment at appropriate doses suppressed arterial remodeling without affecting blood pressure. Our findings indicate that nesfatin-1 can be a therapeutic target for improved treatment of peripheral artery disease.

Poldip2 knockdown inhibits vascular smooth muscle proliferation and neointima formation by regulating the expression of PCNA and p21

Polymerase delta-interacting protein 2 (Poldip2) is a multi-functional protein with numerous roles in the vasculature, including the regulation of cell apoptosis and migration, as well as extracellular matrix deposition; however, its role in VSMC proliferation and neointimal formation is unknown. In this study, we investigated the role of Poldip2 in intraluminal wire-injury induced neointima formation and proliferation of vascular smooth muscle cells in vitro and in vivo. Poldip2 expression was observed in the intima and media of human atherosclerotic arteries, where it colocalized with proliferating cell nuclear antigen (PCNA). Wire injury of femoral arteries of Poldip2^+/+ mice induced robust neointimal formation after 2 weeks, which was impaired in Poldip2^+/‒ mice. PCNA expression was significantly reduced and expression of the cell cycle inhibitor p21 was significantly increased in wire-injured arteries of Poldip2^+/‒ animals compared to wild-type controls. No difference was observed in apoptosis. Downregulation of Poldip2 in rat aortic smooth muscle cells significantly reduced serum-induced proliferation and PCNA expression, but upregulated p21 expression. Downregulation of p21 using siRNA reversed the inhibition of proliferation induced by knockdown of Poldip2. These results indicate that Poldip2 plays a critical role in the proliferation of VSMCs.

Copper transporter ATP7A interacts with IQGAP1, a Rac1 binding scaffolding protein: role in PDGF-induced VSMC migration and vascular remodeling

Vascular smooth muscle cell (VSMC) migration contributes to neointimal formation after vascular injury. We previously demonstrated that copper (Cu) transporter ATP7A is involved in platelet-derived growth factor (PDGF)-induced VSMC migration in a Cu- and Rac1-dependent manner. The underlying mechanism is still unknown. Here we show that ATP7A interacts with IQGAP1, a Rac1 and receptor tyrosine kinase binding scaffolding proteins, which mediates PDGF-induced VSMC migration and vascular remodeling. In cultured rat aortic SMCs, PDGF stimulation rapidly promoted ATP7A association with IQGAP1 and Rac1 and their translocation to the lipid rafts and leading edge. Cotransfection assay revealed that ATP7A directly bound to NH₂-terminal domain of IQGAP1. Functionally, either ATP7A or IQGAP1 depletion using siRNA significantly inhibited PDGF-induced VSMC migration without additive effects, suggesting that IQGAP1 and ATP7A are in the same axis to promote migration. Furthermore, IQGAP1 siRNA blocked PDGF-induced ATP7A association with Rac1 as well as its translocation to leading edge, while PDGF-induced IQGAP1 translocation was not affected by ATP7A siRNA or Cu chelator. Overexpression of mutant IQGAP1 lacking a Rac1 binding site prevented PDGF-induced translocation of Rac1, but not ATP7A, to the leading edge, thereby inhibiting lamellipodia formation and VSMC migration. In vivo, ATP7A colocalized with IQGAP1 at neointimal VSMCs in a mice wire injury model, while neointimal formation and extracellular matrix deposition induced by vascular injury were inhibited in ATP7A mutant mice with reduced Cu transporter function. In summary, IQGAP1 functions as ATP7A and Rac1 binding scaffolding protein to organize PDGF-dependent ATP7A translocation to the lamellipodial leading edge, thereby promoting VSMC migration and vascular remodeling.

Glucose-Dependent Insulinotropic Polypeptide Suppresses Peripheral Arterial Remodeling in Male Mice

Glucose-dependent insulinotropic polypeptide (GIP) exhibits direct cardiovascular actions in addition to its well-known insulinotropic effect. However, the role of GIP in peripheral artery disease remains unclear. In this study, we evaluated the effects of GIP against peripheral arterial remodeling in mouse models. The genetic deletion of GIP receptor (GIPR) led to exaggerated neointimal hyperplasia after transluminal femoral artery wire injury. Conversely, chronic GIP infusion suppressed neointimal hyperplasia and facilitated endothelial regeneration. The beneficial effects of GIP were abrogated by inhibiting nitric oxide (NO) synthase, suggesting a possible mechanism mediated by NO. In cultured human umbilical vein endothelial cells (HUVECs), GIP elevated cytosolic calcium levels without affecting intracellular cAMP levels. Furthermore, GIP dose-dependently increased NO production, whereas this effect was abolished by inhibiting AMP-activated protein kinase (AMPK). GIP induced AMPK phosphorylation, which was abrogated by inhibiting phospholipase C and calcium-calmodulin-dependent protein kinase kinase but not by adenylate cyclase or liver kinase B1, suggesting the existence of a calcium-mediated GIPR signaling pathway. These effects of GIP were retained in severe hyperglycemic Leprdb/ Leprdb mice and in high-glucose-cultured HUVECs. Overall, we demonstrated the protective effects of GIP against peripheral arterial remodeling as well as the involvement of a calcium-mediated GIPR signaling pathway in vascular endothelial cells. Our findings imply the potential vascular benefits of multiple agonists targeting G protein-coupled receptors, including GIPR, which are under development for the treatment of type 2 diabetes.

Engulfment of platelets delays endothelial cell aging via girdin and its phosphorylation

Endothelial cells are critical in angiogenesis and maintain the homeostasis of the blood‑brain barrier (BBB). Platelets (PLTs) are essential in vascular biology, including angiogenesis. The present study aimed to investigate the effect of PLTs on the aging of endothelial cells. Human brain microvascular endothelial cells (HBMECs) and human astrocytes were co‑cultured to mimic the BBB. Transmission electron microscopy was used to observe the engulfment of PLTs. Confocal microscopy was used to observe the co‑localization of PLTs, girders of actin filament (girdin) and phosphorylated (p‑)girdin. Senescence‑associated β‑galactosidase (β‑gal) staining, 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide and flow cytometry were performed to examine the cell senescence, viability and apoptosis, respectively. Transwell assays were performed to examine cell invasion and migration. Western blot analysis was performed to detect the expression of girdin, AKT and p‑AKT. PLTs delayed senescence, and promoted the viability and resistance to apoptosis of the HBMECs. Cell invasion and migration were enhanced by PLTs. In addition, girdin and p‑girdin were essential to the engulfment of HBMECs to PLTs. Mechanically, the inhibition of AKT signals reversed the effect of PLTs on HBMECs by increasing the activity of β‑gal, decreasing the cell viability, and inhibiting the invasion and migration of the HBMECs. The engulfment of PLTs assisted in delaying the aging of endothelial cells via girdin and p‑girdin, in which the AKT signal was involved. The present study indicated a potential strategy for delaying endothelial cell aging in the treatment of central nervous system diseases.

P53 Promotes Retinoid Acid-induced Smooth Muscle Cell Differentiation by Targeting Myocardin

TP53 is a widely studied tumor suppressor gene that controls various cellular functions, including cell differentiation. However, little is known about its functional roles in smooth muscle cells (SMCs) differentiation from embryonic stem cells (ESCs). SMC differentiation is at the heart of our understanding of vascular development, normal blood pressure homeostasis, and the pathogenesis of vascular diseases such as atherosclerosis, hypertension, restenosis, as well as aneurysm. Using retinoid acid (RA)-induced SMC differentiation models, we observed that p53 expression is increased during in vitro differentiation of mouse ESCs into SMCs. Meanwhile, suppression of p53 by shRNA reduced RA-induced SMC differentiation. Mechanistically, we have identified for the first time that Myocardin, a transcription factor that induces muscle cell differentiation and muscle-specific gene expression, is the direct target of p53 by bioinformatic analysis, luciferase reporter assay, and chromatin immunoprecipitation approaches. Moreover, in vivo SMC-selective p53 transgenic overexpression inhibited injury-induced neointimal formation. Taken together, our data demonstrate that p53 and its target gene, Myocardin, play regulatory roles in SMC differentiation. This study may lead to the identification of novel target molecules that may, in turn, lead to novel drug discoveries for the treatment of vascular diseases.

Enhancing amplification of late-outgrowth endothelial cells by bilobalide

Transfusion of autologous late-outgrowth endothelial cells (OECs) is a promising treatment for restenosis after revascularization. Preparing cells by in vitro amplification is a key step to implement the therapy. This study aimed to demonstrate that bilobalide, a terpenoid, enhances the OEC amplification. Human-, rabbit- and rat OECs and a mouse femoral artery injury model were used. Expanding OECs used endothelial growth medium-2 as the standard culture medium while exploring the mechanisms used endothelial basal medium-2. Proliferation assay used MTT method and BrdU method. Migration assay used the modified Boyden chamber. Intracellular nitric oxide, superoxide anion, hydroxyl radical/peroxynitrite and H₂ O₂ were quantified with DAF-FM DA, dihydroethidium, hydroxyphenyl fluorescein and a H₂ O₂ assay kit, respectively. Activated ERK1/2 and eNOS were tested with the Western blot. Bilobalide concentration-dependently enhanced OEC number increase in vitro. Transfusion of bilobalide-based human OECs into femoral injured athymia nude mouse reduced the intimal hyperplasia. Bilobalide promoted OEC proliferation and migration and increased the intracellular nitric oxide level. L-NAME, a NOS inhibitor, inhibits but not abolishes OEC proliferation, migration and ERK1/2 activation. Bilobalide concentration-dependently enhanced the eNOS Ser-1177 phosphorylation and Thr-495 dephosphorylation in activated OECs. Bilobalide alleviates the increase in hydroxyl radical/peroxynitrite, superoxide anion and H₂ O₂ in proliferating OECs. In conclusion, nitric oxide plays a partial role in OEC proliferation and migration; bilobalide increases OEC nitric oxide production and decreases nitric oxide depletion, promoting the OEC number increase; Bilobalide-based OECs are active in vivo. The findings may simplify the preparation of OECs, facilitating the implementation of the autologous-OECs-transfusion therapy.

Balloon-based Injury to Induce Myointimal Hyperplasia in the Mouse Abdominal Aorta

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine balloon denudation model, which is comparable with established vessel injury models in large animals. The aorta denudation model with balloon catheters mimics the clinical setting and leads to comparable pathobiological and physiological changes. Briefly, after performing a horizontal incision in the aorta abdominalis, a balloon catheter will be inserted into the vessel, inflated, and introduced retrogradely. Inflation of the balloon will lead to intima injury and overdistension of the vessel. After removing the catheter, the aortic incision will be closed with single stiches. The model shown in this article is reproducible, easy to perform, and can be established quickly and reliably. It is especially suitable for evaluating expensive experimental therapeutic agents, which can be applied in an economical fashion. By using different knockout-mouse strains, the impact of different genes on MH development can be assessed.

Experimental Models of Cardiovascular Diseases: Overview

Cardiovascular disease is one of the most common causes of deaths in clinics. Experimental models of cardiovascular diseases are essential to understand disease mechanism, to provide accurate diagnoses, and to develop new therapies. Large numbers of experimental models have been proposed and replicated by many laboratories in the past. Models with significant advantages are chosen and became more popular. Particularly, feasibility, reproducibility, and human disease resemblance are the common key factors for frequently used cardiovascular disease models. In this chapter, we provide a brief overview of these experimental models used for in vitro, in vivo, and in silico studies of cardiovascular diseases.

Mouse Model of Wire Injury-Induced Vascular Remodeling

We introduced the vascular remodeling mouse system induced by the wire injury to investigate the molecular and cellular mechanisms of cardiovascular diseases. Using these models, we focus on the adventitial cell population in the outermost layer of the adult vasculature as a vascular progenitor niche. Firstly we used the standard wire injury approach, leaving the wire for 1 min in the artery and retracting the wire by twisting out to expand the artery and denude the inner layer endothelial cells in the both peripheral artery and femoral artery. This method leads to adventitial lineage cell accumulation on the medial-adventitial border, but no contribution into the hyperplastic neointima. Since advanced atherosclerotic plaques in the mouse models and human clinical specimens show the elastic lamina in the media broken, we hypothesized that adventitial lineage cells contribute to acute neointima formation induced by the mechanical damage in both endothelial and medial layers. To make this intensive damage, next, we used the bigger diameter wire with no hydrophilic coating and repeated the ten-times insertion and retraction of the wire after leaving for 1 min in the femoral artery. The additional ten-times intensive movements of the wire lead to breakdown and rupture of the elastic lamina together with a contribution of adventitial lineage cells to the hyperplastic neointima. Here we describe these two different wire injury methods to induce different types of vascular remodeling at the point of adventitial lineage cell contribution to the hyperplastic neointima by targeting two separate locations of hind limb artery, the peripheral artery and femoral artery, and using two different diameter wires.

Inhibition of activated factor X by rivaroxaban attenuates neointima formation after wire-mediated vascular injury

Accumulating evidence suggests that activated factor X (FXa), a key coagulation factor, plays an important role in the development of vascular inflammation through activation of many cell types. Here, we investigated whether pharmacological blockade of FXa attenuates neointima formation after wire-mediated vascular injury. Transluminal femoral artery injury was induced in C57BL/6 mice by inserting a straight wire. Rivaroxaban (5mg/kg/day), a direct FXa inhibitor, was administered from one week before surgery until killed. At four weeks after surgery, rivaroxaban significantly attenuated neointima formation in the injured arteries compared with control (P<0.01). Plasma lipid levels and blood pressure were similar between the rivaroxaban-treated group and non-treated group. Quantitative RT-PCR analyses demonstrated that rivaroxaban reduced the expression of inflammatory molecules (e.g., IL-1β and TNF-α) in injured arteries at seven days after surgery (P<0.05, respectively). In vitro experiments using mouse peritoneal macrophages demonstrated that FXa increased the expression of inflammatory molecules (e.g., IL-1β and TNF-α), which was blocked in the presence of rivaroxaban (P<0.05). Also, in vitro experiments using rat vascular smooth muscle cells (VSMC) demonstrated that FXa promoted both proliferation and migration of this cell type (P<0.05), which were blocked in the presence of rivaroxaban. Inhibition of FXa by rivaroxaban attenuates neointima formation after wire-mediated vascular injury through inhibition of inflammatory activation of macrophages and VSMC.

The Role of Age-Related Intimal Remodeling and Stiffening in Atherosclerosis

Age-related vascular stiffening is closely associated with cardiovascular risk. The clinical measure of arterial stiffness, pulse wave velocity, reflects bulk structural changes in the media observed with age, but does not reflect intimal remodeling that also drives atherosclerosis. Endothelial barrier integrity is disrupted during early atherogenesis and is regulated by the mechanics and composition of the underlying intima, which undergoes significant atherogenic remodeling in response to age and hemodynamics. Here, we first review the best characterized of these changes, including physiological intimal thickening throughout the arterial tree, fibronectin and collagen deposition, and collagen cross-linking. We then address the most common in vivo and in vitro models used to gain mechanistic insight into the consequences of intimal remodeling. Finally, we consider the impacts of intimal stiffening upon endothelial cell mechanotransduction with emphasis on the emerging impact of increased complexity in cellular traction forces and substrate rigidity upon endothelial barrier integrity.

The role of endothelial nitric oxide in the anti-restenotic effects of liraglutide in a mouse model of restenosis

Background

Previous animal studies have shown that glucagon-like peptide-1 receptor agonists (GLP-1RAs) suppress arterial restenosis, a major complication of angioplasty, presumably through their direct action on vascular smooth muscle cells. However, the contribution of vascular endothelial cells (VECs) to this process remains unknown. In addition, the potential interference caused by severe hyperglycemia and optimal treatment regimen remain to be determined.

Methods

Nine-week-old male C57BL6 (wild-type) and diabetic db/db mice were randomly divided into vehicle or liraglutide treatment groups (Day 1), and subject to femoral artery wire injuries (Day 3). The injured arteries were collected on Day 29 for morphometric analysis. Human umbilical vein endothelial cells (HUVECs) were used for in vitro experiments. One-way ANOVA, followed by Tukey’s test, was used for comparisons.

Results

In wild-type mice, liraglutide treatment (5.7, 17, or 107 nmol/kg/day) dose-dependently reduced the neointimal area (20, 50, and 65%) without inducing systemic effects, and caused an associated decrease in the percentage of vascular proliferating cells. However, these effects were completely abolished by the nitric oxide synthase (NOS) inhibitor N-omega-nitro-l-arginine methyl ester. Next, we investigated the optimal treatment regimen. Early treatment (Days 1–14) was as effective in reducing the neointimal area and vascular cell proliferation as full treatment (Days 1–29), whereas delayed treatment (Days 15–29) was ineffective. In HUVECs, liraglutide treatment dose-dependently stimulated NO production, which was dependent on GLP-1R, cAMP, cAMP-dependent protein kinase, AMP-activated protein kinase (AMPK), and NOS. Subsequently, we investigated the role of liver kinase B (LKB)-1 in this process. Liraglutide increased the phosphorylation of LKB-1, and siRNA-induced LKB-1 knockdown abolished liraglutide-stimulated NO production. In severe hyperglycemic db/db mice, liraglutide treatment also suppressed neointimal hyperplasia, which was accompanied by reductions in vascular cell proliferation and density. Furthermore, liraglutide treatment suppressed hyperglycemia-enhanced vascular inflammation 7 days after arterial injury.

Conclusions

We demonstrate that endothelial cells are targets of liraglutide, and suppress restenosis via endothelial NO. Furthermore, the protective effects are maintained in severe hyperglycemia. Our findings provide an evidence base for a future clinical trial to determine whether treatment with GLP-1RAs represents potentially effective pharmacological therapy following angioplasty in patients with diabetes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0603-x) contains supplementary material, which is available to authorized users.

The novel mineralocorticoid receptor antagonist finerenone attenuates neointima formation after vascular injury

BACKGROUND

The novel nonsteroidal mineralocorticoid receptor (MR) antagonist finerenone holds promise to be safe and efficient in the treatment of patients with heart failure and/or chronic kidney disease. However, its effects on vascular function remain elusive.

PURPOSE

The aim of this study was to determine the functional effect of selective MR antagonism by finerenone in vascular cells in vitro and the effect on vascular remodeling following acute vascular injury in vivo.

METHODS AND RESULTS

In vitro, finerenone dose-dependently reduced aldosterone-induced smooth muscle cell (SMC) proliferation, as quantified by BrdU incorporation, and prevented aldosterone-induced endothelial cell (EC) apoptosis, as measured with a flow cytometry based caspase 3/7 activity assay. In vivo, oral application of finerenone resulted in an accelerated re-endothelialization 3 days following electric injury of the murine carotid artery. Furthermore, finerenone treatment inhibited intimal and medial cell proliferation following wire-induced injury of the murine femoral artery 10 days following injury and attenuated neointimal lesion formation 21 days following injury.

CONCLUSION

Finerenone significantly reduces apoptosis of ECs and simultaneously attenuates SMC proliferation, resulting in accelerated endothelial healing and reduced neointima formation of the injured vessels. Thus, finerenone appears to provide favorable vascular effects through restoring vascular integrity and preventing adverse vascular remodeling.

Ectopic Fatty Acid-Binding Protein 4 Expression in the Vascular Endothelium is Involved in Neointima Formation After Vascular Injury

Background

Fatty acid‐binding protein 4 (FABP4) is expressed in adipocytes, macrophages, and endothelial cells of capillaries but not arteries. FABP4 is secreted from adipocytes in association with lipolysis, and an elevated circulating FABP4 level is associated with obesity, insulin resistance, and atherosclerosis. However, little is known about the link between FABP4 and endovascular injury. We investigated the involvement of ectopic FABP4 expression in endothelial cells in neointima hyperplasia after vascular injury.

Methods and Results

Femoral arteries of 8‐week‐old male mice were subjected to wire‐induced vascular injury. After 4 weeks, immunofluorescence staining showed that FABP4 was ectopically expressed in endothelial cells of the hyperplastic neointima. Neointima formation determined by intima area and intima to media ratio was significantly decreased in FABP4‐defficient mice compared with that in wild‐type mice. Adenovirus‐mediated overexpression of FABP4 in human coronary artery endothelial cells (HCAECs) in vitro increased inflammatory cytokines and decreased phosphorylation of nitric oxide synthase 3. Furthermore, FABP4 was secreted from HCAECs. Treatment of human coronary smooth muscle cells or HCAECs with the conditioned medium of Fabp4‐overexpressed HCAECs or recombinant FABP4 significantly increased gene expression of inflammatory cytokines and proliferation‐ and adhesion‐related molecules in cells, promoted cell proliferation and migration of human coronary smooth muscle cells, and decreased phosphorylation of nitric oxide synthase 3 in HCAECs, which were attenuated in the presence of an anti‐FABP4 antibody.

Conclusions

Ectopic expression and secretion of FABP4 in vascular endothelial cells contribute to neointima formation after vascular injury. Suppression of ectopic FABP4 in the vascular endothelium would be a novel strategy against post‐angioplasty vascular restenosis.

Pioglitazone Attenuates Injury-Induced Neointima Formation in Mouse Femoral Artery Partially through the Activation of AMP-Activated Protein Kinase

BACKGROUND/AIMS

Pioglitazone (PIO), an antidiabetic drug, has been shown to attenuate vascular smooth muscle cell (VSMC) proliferation, which is a major event in atherosclerosis and restenosis after angioplasty. Till date, the likely contributory role of AMP-activated protein kinase (AMPK) toward PIO inhibition of VSMC proliferation has not been examined in vivo. This study is aimed at determining whether pharmacological inhibition of AMPK would prevent the inhibitory effect of PIO on neointima formation in a mouse model of arterial injury.

METHODS

Male CJ57BL/6J mice were subjected to femoral artery injury using guidewire. PIO (20 mg/kg/day) was administered orally 1 day before surgery and for 3 weeks until sacrifice in the absence or presence of compound C (an AMPK inhibitor). Injured femoral arteries were used for morphometric analysis of neointima formation. Aortic tissue lysates were used for immunoblot analysis of phosphorylated AMPK.

RESULTS

PIO treatment resulted in a significant decrease in intima-to-media ratio by ∼50.3% (p < 0.05, compared with vehicle control; n = 6), which was accompanied by enhanced phosphorylation of AMPK by ∼85% in the vessel wall. Compound C treatment led to a marked reduction in PIO-mediated inhibition of neointima formation.

CONCLUSION

PIO attenuates injury-induced neointima formation, in part, through the activation of AMPK.

Protective Function of Ahnak1 in Vascular Healing after Wire Injury

AIM

Vascular remodeling following injury substantially accounts for restenosis and adverse clinical outcomes. In this study, we investigated the role of the giant scaffold protein Ahnak1 in vascular healing after endothelial denudation of the murine femoral artery.

METHODS

The spatiotemporal expression pattern of Ahnak1 and Ahnak2 was examined using specific antibodies and real-time quantitative PCR. Following wire-mediated endothelial injury of Ahnak1-deficient mice and wild-type (WT) littermates, the processes of vascular healing were analyzed.

RESULTS

Ahnak1 and Ahnak2 showed a mutually exclusive vascular expression pattern, with Ahnak1 being expressed in the endothelium and Ahnak2 in the medial cells in naïve WT arteries. After injury, a marked increase of Ahnak1- and Ahnak2-positive cells at the lesion site became evident. Both proteins showed a strong upregulation in neointimal cells 14 days after injury. Ahnak1-deficient mice showed delayed vascular healing and dramatically impaired re-endothelialization that resulted in prolonged adverse vascular remodeling, when compared to the WT littermates.

CONCLUSION

The large scaffold and adaptor proteins Ahnak1 and Ahnak2 exhibit differential expression patterns and functions in naïve and injured arteries. Ahnak1 plays a nonredundant protective role in vascular healing.

Vasoprotective Activities of the Adrenomedullin-RAMP2 System in Endothelial Cells

Neointimal hyperplasia is the primary lesion underlying atherosclerosis and restenosis after coronary intervention. We previously described the essential angiogenic function of the adrenomedullin (AM)-receptor activity-modifying protein (RAMP) 2 system. In the present study, we assessed the vasoprotective actions of the endogenous AM-RAMP2 system using a wire-induced vascular injury model. We found that neointima formation and vascular smooth muscle cell proliferation were enhanced in RAMP2+/- male mice. The injured vessels from RAMP2+/- mice showed greater macrophage infiltration, inflammatory cytokine expression, and oxidative stress than vessels from wild-type mice and less re-endothelialization. After endothelial cell-specific RAMP2 deletion in drug-inducible endothelial cell-specific RAMP2-/- (DI-E-RAMP2-/-) male mice, we observed markedly greater neointima formation than in control mice. In addition, neointima formation after vessel injury was enhanced in mice receiving bone marrow transplants from RAMP2+/- or DI-E-RAMP2-/- mice, indicating that bone marrow-derived cells contributed to the enhanced neointima formation. Finally, we found that the AM-RAMP2 system augmented proliferation and migration of endothelial progenitor cells. These results demonstrate that the AM-RAMP2 system exerts crucial vasoprotective effects after vascular injury and could be a therapeutic target for the treatment of vascular diseases.

A novel lipoprotein (a) lowering drug, D-47, decreases neointima thickening after vascular injury

Although Lp(a) have been thought to be a cardiovascular risk factor, it is unclear whether lowering Lp(a) levels reduces the risk of cardiovascular diseases. No pharmacological agents which selectively reduce serum Lp(a) levels, and Lp(a) is present in primate but absent in common laboratory animals such as mice and pigs. In the present study we used transgenic mice of human Lp(a) and tested effect a novel Lp(a) lowering drug D-47 on neointima formation after vascular injury. D-47 successfully decreased plasma levels of Lp(a) and possibly inhibited neointima formation in Lp(a) transgenic mice. The results indicate that we can modulate plasma Lp(a) levels by pharmacologic agents and inhibit atherogenic properties of Lp(a) by reducing plasma levels of Lp(a). J. Med. Invest. 64: 64-67, February, 2017.

AdipoRon, an adiponectin receptor agonist, attenuates PDGF-induced VSMC proliferation through inhibition of mTOR signaling independent of AMPK: Implications toward suppression of neointimal hyperplasia

Hypoadiponectinemia is associated with an increased risk of coronary artery disease. Although adiponectin replenishment mitigates neointimal hyperplasia and atherosclerosis in mouse models, adiponectin therapy has been hampered in a clinical setting due to its large molecular size. Recent studies demonstrate that AdipoRon (a small-molecule adiponectin receptor agonist) improves glycemic control in type 2 diabetic mice and attenuates postischemic cardiac injury in adiponectin-deficient mice, in part, through activation of AMP-activated protein kinase (AMPK). To date, it remains unknown as to whether AdipoRon regulates vascular smooth muscle cell (VSMC) proliferation, which plays a major role in neointima formation. In the present study, oral administration of AdipoRon (50mg/kg) in C57BL/6J mice significantly diminished arterial injury-induced neointima formation by ∼57%. Under in vitro conditions, AdipoRon treatment led to significant inhibition of platelet-derived growth factor (PDGF)-induced VSMC proliferation, DNA synthesis, and cyclin D1 expression. While AdipoRon induced a rapid and sustained activation of AMPK, it also diminished basal and PDGF-induced phosphorylation of mTOR and its downstream targets, including p70S6K/S6 and 4E-BP1. However, siRNA-mediated AMPK downregulation showed persistent inhibition of p70S6K/S6 and 4E-BP1 phosphorylation, indicating AMPK-independent effects for AdipoRon inhibition of mTOR signaling. In addition, AdipoRon treatment resulted in a sustained and transient decrease in PDGF-induced phosphorylation of Akt and ERK, respectively. Furthermore, PDGF receptor-β tyrosine phosphorylation, which controls the phosphorylation state of Akt and ERK, was diminished upon AdipoRon treatment. Together, the present findings suggest that orally-administered AdipoRon has the potential to limit restenosis after angioplasty by targeting mTOR signaling independent of AMPK activation.

Sulforaphane inhibits platelet-derived growth factor-induced vascular smooth muscle cell proliferation by targeting mTOR/p70S6kinase signaling independent of Nrf2 activation

Activation of nuclear factor erythroid 2-related factor 2 (Nrf2, a transcription factor) and/or inhibition of mammalian target of rapamycin (mTOR) are implicated in the suppression of vascular smooth muscle cell (VSMC) proliferation. The present study has examined the likely regulatory effects of sulforaphane (SFN, an antioxidant) on Nrf2 activation and platelet-derived growth factor (PDGF)-induced mTOR signaling in VSMCs. Using human aortic VSMCs, nuclear extraction and siRNA-mediated downregulation studies were performed to determine the role of Nrf2 on SFN regulation of PDGF-induced proliferative signaling. Immunoprecipitation and/or immunoblot studies were carried out to determine how SFN regulates PDGF-induced mTOR/p70S6K/S6 versus ERK and Akt signaling. Immunohistochemical analysis was performed to determine SFN regulation of S6 phosphorylation in the injured mouse femoral artery. SFN (5μM) inhibits PDGF-induced activation of mTOR without affecting mTOR association with raptor in VSMCs. While SFN inhibits PDGF-induced phosphorylation of p70S6K and 4E-BP1 (downstream targets of mTOR), it does not affect ERK or Akt phosphorylation. In addition, SFN diminishes exaggerated phosphorylation of S6 ribosomal protein (a downstream target of p70S6K) in VSMCs in vitro and in the neointimal layer of injured artery in vivo. Although SFN promotes Nrf2 accumulation to upregulate cytoprotective genes (e.g., heme oxygenase-1 and thioredoxin-1), downregulation of endogenous Nrf2 by target-specific siRNA reveals an Nrf2-independent effect for SFN-mediated inhibition of mTOR/p70S6K/S6 signaling and suppression of VSMC proliferation. Strategies that utilize local delivery of SFN at the lesion site may limit restenosis after angioplasty by targeting mTOR/p70S6K/S6 axis in VSMCs independent of Nrf2 activation.

C1q/TNF-related protein 1 prevents neointimal formation after arterial injury

BACKGROUND AND AIMS

Obesity contributes to the progression of vascular disorders. C1q/TNF-related protein (CTRP) 1 is a circulating adipokine, which is upregulated in obese complications including coronary artery disease. Here, we investigated the role of CTRP1 in regulation of vascular remodeling after mechanical injury and evaluated its potential mechanism.

METHODS

Mice were subjected to wire-induced injury of left femoral arteries. An adenoviral vector encoding CTRP1 (Ad-CTRP1) or β-galactosidase as a control was injected into the jugular vein of mice 3 days prior to surgery.

RESULTS

Systemic administration of Ad-CTRP1 to wild-type mice led to reduction of the neointimal thickening after wire-induced arterial injury and the number of bromodeoxyuridine-positive cells in injured vessels as compared with treatment with control vectors. Treatment of vascular smooth muscle cells (VSMCs) with CTRP1 protein attenuated proliferative activity and ERK phosphorylation in response to PDGF-BB. CTRP1 treatment increased cyclic AMP (cAMP) levels in VSMCs, and inhibition of adenylyl cyclase reversed the inhibitory effect of CTRP1 on VSMC growth and ERK phosphorylation. Antagonization of sphingosine-1-phosphaterote (S1P) receptor 2 blocked the effects of CTRP1 on cAMP production and VSMC growth. Furthermore, CTRP1-knockout mice had enhanced neointimal thickening following injury and increased numbers of proliferating cells in neointima compared to control WT mice.

CONCLUSIONS

These findings indicate that CTRP1 functions to prevent the development of pathological vascular remodeling by reducing VSMC growth through the cAMP-dependent pathway.