MicroRNA Regulation of Vascular Smooth Muscle Function and Phenotype

New insights on genetic background of major diabetic vascular complications

BACKGROUND

By 2045, it is expected that 693 million individuals worldwide will have diabetes and with greater risk of morbidity, mortality, loss of vision, renal failure, and a decreased quality of life due to the devastating effects of macro- and microvascular complications. As such, clinical variables and glycemic control alone cannot predict the onset of vascular problems. An increasing body of research points to the importance of genetic predisposition in the onset of both diabetes and diabetic vascular complications.

OBJECTIVES

Purpose of this article is to review these approaches and narrow down genetic findings for Diabetic Mellitus and its consequences, highlighting the gaps in the literature necessary to further genomic discovery.

MATERIAL AND METHODS

In the past, studies looking for genetic risk factors for diabetes complications relied on methods such as candidate gene studies, which were rife with false positives, and underpowered genome-wide association studies, which were constrained by small sample sizes.

RESULTS

The number of genetic findings for diabetes and diabetic complications has over doubled due to the discovery of novel genomics data, including bioinformatics and the aggregation of global cohort studies. Using genetic analysis to determine whether diabetes individuals are at the most risk for developing diabetic vascular complications (DVC) might lead to the development of more accurate early diagnostic biomarkers and the customization of care plans.

CONCLUSIONS

A newer method that uses extensive evaluation of single nucleotide polymorphisms (SNP) in big datasets is Genome-Wide Association Studies (GWAS).

Expression of miRNA-29c in the carotid plaque and its association with diabetic mellitus

Background

Carotid artery atherosclerosis is a major cause of ischemic stroke, and ischemic stroke is the leading cause of morbidity and mortality worldwide. Unfortunately, the reason for the build-up of atherosclerosis plaque is unknown. The miRNA-29c was reported to promote the phenotype transformation of vascular smooth muscle cells (VSMCs) in diabetes mice, eventually leading to plaque formation and bleeding. However, such studies are rare and limited to animal experiments.

Methods

In our study, 40 patients were divided into a diabetic mellitus (DM) group and a non-DM group according to whether they were diagnosed with DM. Then, the real-time quantitative PCR was applied to examine the miRNA-29c level in human carotid plaque tissue derived from 40 subjects receiving carotid endarterectomy.

Results

Briefly, diabetes patients had a decreased miRNA-29c level as compared with non-DM subjects, and this comparison was statistically significant (P = 0.02). Notably, variable miRNA-29c level was negatively associated with HbA1c level, although no statistical significance was observed. Moreover, there was an increased miRNA-29c level in patients with cerebral stroke.

Conclusion

Collectively, the miRNA-29c level in the carotid plaque is closely associated with DM and cerebral stroke, which may contribute to atherosclerosis formation.

Cold exposure protects against medial arterial calcification development via autophagy

Medial arterial calcification (MAC), a systemic vascular disease different from atherosclerosis, is associated with an increased incidence of cardiovascular events. Several studies have demonstrated that ambient temperature is one of the most important factors affecting cardiovascular events. However, there has been limited research on the effect of different ambient temperatures on MAC. In the present study, we showed that cold temperature exposure (CT) in mice slowed down the formation of vitamin D (VD)-induced vascular calcification compared with room temperature exposure (RT). To investigate the mechanism involved, we isolated plasma-derived exosomes from mice subjected to CT or RT for 30 days (CT-Exo or RT-Exo, respectively). Compared with RT-Exo, CT-Exo remarkably alleviated the calcification/senescence formation of vascular smooth muscle cells (VSMCs) and promoted autophagy by activating the phosphorylation of AMP-activated protein kinase (p-AMPK) and inhibiting phosphorylation of mammalian target of rapamycin (p-mTOR). At the same time, CT-Exo promoted autophagy in β-glycerophosphate (β-GP)-induced VSMCs. The number of autophagosomes and the expression of autophagy-related proteins ATG5 and LC3B increased, while the expression of p62 decreased. Based on a microRNA chip microarray assay and real-time polymerase chain reaction, miR-320a-3p was highly enriched in CT-Exo as well as thoracic aortic vessels in CT mice. miR-320a-3p downregulation in CT-Exo using AntagomiR-320a-3p inhibited autophagy and blunted its anti-calcification protective effect on VSMCs. Moreover, we identified that programmed cell death 4 (PDCD4) is a target of miR-320a-3p, and silencing PDCD4 increased autophagy and decreased calcification in VSMCs. Treatment with CT-Exo alleviated the formation of MAC in VD-treated mice, while these effects were partially reversed by GW4869. Furthermore, the anti-arterial calcification protective effects of CT-Exo were largely abolished by AntagomiR-320a-3p in VD-induced mice. In summary, we have highlighted that prolonged cold may be a good way to reduce the incidence of MAC. Specifically, miR-320a-3p from CT-Exo could protect against the initiation and progression of MAC via the AMPK/mTOR autophagy pathway.

Restoring endothelial function: shedding light on cardiovascular stent development

Complete endothelialization is highly important for maintaining long-term patency and avoiding subsequent complications in implanting cardiovascular stents. It not only refers to endothelial cells (ECs) fully covering the inserted stents, but also includes the newly formed endothelium, which could exert physiological functions, such as anti-thrombosis and anti-stenosis. Clinical outcomes have indicated that endothelial dysfunction, especially the insufficiency of antithrombotic and barrier functions, is responsible for stent failure. Learning from vascular pathophysiology, endothelial dysfunction on stents is closely linked to the microenvironment of ECs. Evidence points to inflammatory responses, oxidative stress, altered hemodynamic shear stress, and impaired endothelial barrier affecting the normal growth of ECs, which are the four major causes of endothelial dysfunction. The related molecular mechanisms and efforts dedicated to improving the endothelial function are emphasized in this review. From the perspective of endothelial function, the design principles, advantages, and disadvantages behind current stents are introduced to enlighten the development of new-generation stents, aiming to offer new alternatives for restoring endothelial function.

Circulating miRNAs as biomarkers for diagnosis, surveillance and post-operative follow-up of abdominal aortic aneurysms

OBJECTIVE

To provide a summary of the current state of research in English medical literature on circulating miRNAs, as biomarkers for AAA. Additionally, for the most commonly mentioned circulating miRNAs in the literature, to attempt a documentation of the biological mechanisms underlying their role in AAA development.

METHODS

A literature search was undertaken in the MEDLINE database. Only reports that involved peripheral blood samples (whole blood, plasma, serum) were included. The following terms were used in combination: microrna, mirna, abdominal aortic aneurysm, human, circulating, plasma, serum, endovascular and EVAR.

RESULTS

A total of 25 reports, published from 2012 to 2022 were included with a total of 1259 patients with AAA, predominantly men (N= 1040, 90%). Six of these reports recruited healthy donors who underwent ultrasound screening for AAA as control samples. The majority of studies were undertaken in plasma samples and the most preferred microRNA profiling method was Real - Time quantitative polymerase chain reaction (qRT-PCR). The following nine miRNAs (out of a total of 76) were studied in more than two references: miR-145, miR-24, miR-33, miR-125, let-7, miR-15, miR-191, miR-29 and miR-133.

CONCLUSION

The nine miRNAs described in this study, are implicated in known pathogenetic mechanisms of AAA such as atherosclerosis, vascular smooth muscle cell phenotype switch and apoptosis, vascular inflammation, extracellular matrix degradation and lipid metabolism. Identifying disease-specific miRNAs, in combination with other clinical parameters, as indicators of AAA, is crucial for early diagnosis as well as follow-up of AAAs. For future research on miRNAs as AAA biomarkers, strict case and control group definitions, sample acquisition protocols, and miRNA expression profiling techniques are warranted.

Vascular smooth muscle cells in atherosclerosis: time for a re-assessment

Vascular smooth muscle cells (VSMCs) are key participants in both early and late-stage atherosclerosis. VSMCs invade the early atherosclerotic lesion from the media, expanding lesions, but also forming a protective fibrous cap rich in extracellular matrix to cover the 'necrotic' core. Hence, VSMCs have been viewed as plaque-stabilizing, and decreased VSMC plaque content-often measured by expression of contractile markers-associated with increased plaque vulnerability. However, the emergence of lineage-tracing and transcriptomic studies has demonstrated that VSMCs comprise a much larger proportion of atherosclerotic plaques than originally thought, demonstrate multiple different phenotypes in vivo, and have roles that might be detrimental. VSMCs down-regulate contractile markers during atherosclerosis whilst adopting alternative phenotypes, including macrophage-like, foam cell-like, osteochondrogenic-like, myofibroblast-like, and mesenchymal stem cell-like. VSMC phenotypic switching can be studied in tissue culture, but also now in the media, fibrous cap and deep-core region, and markedly affects plaque formation and markers of stability. In this review, we describe the different VSMC plaque phenotypes and their presumed cellular and paracrine functions, the regulatory mechanisms that control VSMC plasticity, and their impact on atherogenesis and plaque stability.

Arterial Stiffness in Type 1 Diabetes: The Case for the Arterial Wall Itself as a Target Organ

Arterial stiffness (AS) integrates the cumulative burden of known and unknown cardiovascular risk factors on the elastic wall of large arteries along the lifespan of an individual. As a marker of vascular aging, AS is an independent predictor of cardiovascular events and improves cardiovascular risk prediction when added to the Framingham Risk Score. In addition, AS may affect the microvasculature and promote the development of microvascular complications. Its impact on both the macro- and microvasculature has led to the concept that the arterial wall itself should be considered as a target organ. Here, we review the biological and clinical consequences of AS on the macro- and microvasculature and the measurement of AS in routine clinical practice. We also discuss the pathophysiological mechanisms underpinning AS development using diabetes and, in particular, type 1 diabetes, as a disease model with a high risk of cardiovascular events and microvascular complications that are accelerated by AS.

A narrative review of exosomes in vascular calcification

Vascular calcification (VC) is the abnormal deposition of calcium, phosphorus, and other minerals in the vessel wall and can be commonly observed in diabetes, chronic kidney disease, and chronic inflammatory disease. It is closely associated with mortality from cardiovascular events. Traditionally, calcification is considered as a degenerative disease associated with the aging process, while increasing evidence has shown that the occurrence and development of calcification is an active biological process, which is highly regulated by multiple factors. The molecular mechanisms of VC have not yet been fully elucidated. Exosomes, as important transporters of substance transport and intercellular communication, have been shown to participate in VC. The regulation of VC by exosomes involves a number of complex biological processes, which occur through a variety of interaction mechanisms. However, the specific role and mechanism of exosomes in the process of VC are still not fully understood and require further study. This review will briefly describe the roles of exosomes in the process of VC including in the promotion of extracellular mineral deposits, induction of phenotypic conversion of vascular smooth muscle cells (VSMCs), transport of microRNA between cells, and regulation on autophagy and oxidative stress, with the aim of providing novel ideas for the clinical diagnosis and treatment of VC.

Exosomes and Exosomal MicroRNAs in Age-Associated Stroke

Aging has been considered to be the most important non-modifiable risk factor for stroke and death. Changes in circulation factors in the systemic environment, cellular senescence and artery hypertension during human ageing have been investigated. Exosomes are nanosize membrane vesicles that can regulate target cell functions via delivering their carried bioactive molecules (e.g. protein, mRNA, and microRNAs). In the central nervous system, exosomes and exosomal microRNAs play a critical role in regulating neurovascular function, and are implicated in the initiation and progression of stroke. MicroRNAs are small non-coding RNAs that have been reported to play critical roles in various biological processes. Recently, evidence has shown that microRNAs are packaged into exosomes and can be secreted into the systemic and tissue environment. Circulating microRNAs participate in cellular senescence and contribute to age-associated stroke. Here, we provide an overview of current knowledge on exosomes and their carried microRNAs in the regulation of cellular and organismal ageing processes, demonstrating the potential role of exosomes and their carried microRNAs in age-associated stroke.

TWIST1 induces phenotypic switching of vascular smooth muscle cells by downregulating p68 and microRNA-143/145

TWIST1 is an important basic helix‐loop‐helix protein linked to multiple physiological and pathological processes. Although TWIST1 is believed to be involved in vascular pathogenesis, its effects on homeostasis of smooth muscle cells (SMCs) remain poorly understood. Here, we show that TWIST1 protein levels were significantly elevated during SMC phenotypic switching in vivo and in vitro. TWIST1 overexpression promoted phenotypic switching of SMCs, while siRNA targeting of TWIST1 prevented cell transition. Mechanistically, TWIST1 decreased the level of microRNA‐143/145, which governs smooth muscle marker gene transcription. In addition, TWIST1 repressed p68 mRNA and protein expression, a crucial modulator of SMC behavior and microRNA biogenesis. Our co‐immunoprecipitation assay demonstrated a previously unrecognized molecular interaction between TWIST1 and p68 protein. Finally, we found that TWIST1 triggered SMC phenotypic switching and suppressed microRNA‐143/145 expression by promoting the proteasomal degradation of p68. These data suggest a novel role of TWIST1 in the regulation of SMC homeostasis by modulating p68/microRNA‐143/145 axis.

Role of smooth muscle cells in Cardiovascular Disease

Normally, smooth muscle cells (SMCs) are localized in the tunica media of the vasculature, where they take responsibility for vascular contraction and extracellular matrix (ECM) generation. SMCs also play a significant role in obedience and elastic rebound of the artery in response to the haemodynamic condition. However, under pathological or stressed conditions, phenotype switching from contractile to synthetic state or other cell types will occur in SMCs to positively or negatively contribute to disease progression. Various studies demonstrated that functional changes of SMCs are implicated in several cardiovascular diseases. In this review, we present the function of vascular SMCs (VSMCs) and the involved molecular mechanisms about phenotype switching, and summarize the roles of SMCs in atherosclerosis, hypertension, arterial aneurysms and myocardial infarction, hoping to obtain potential therapeutic targets against cardiovascular disease in the clinical practices.

MicroRNA‑125a‑mediated regulation of the mevalonate signaling pathway contributes to high glucose‑induced proliferation and migration of vascular smooth muscle cells

Hyperglycemia contributes to the excessive proliferation and migration of vascular smooth muscle cells (VSMC), which are closely associated with atherosclerosis. MicroRNAs (miRNAs/miRs) constitute a novel class of gene regulators, which have important roles in various pathological conditions. The aim of the present study was to identify miRNAs involved in the high glucose (HG)‑induced VSMC phenotype switch, and to investigate the underlying mechanism. miRNA sequencing and reverse transcription‑quantitative PCR results indicated that inhibition of miR‑125a expression increased the migration and proliferation of VSMCs following HG exposure, whereas the overexpression of miR‑125a abrogated this effect. Furthermore, dual‑luciferase reporter assay results identified that 3‑hydroxy‑3-methyglutaryl‑coA reductase (HMGCR), one of the key enzymes in the mevalonate signaling pathway, is a target of miR‑125a. Moreover, HMGCR knockdown, similarly to miR‑125a overexpression, suppressed HG‑induced VSMC proliferation and migration. These results were consistent with those from the miRNA target prediction programs. Using a rat model of streptozotocin‑induced diabetes mellitus, it was demonstrated that miR‑125a expression was gradually downregulated, and that the expressions of key enzymes in the mevalonate signaling pathway in the aortic media were dysregulated after several weeks. In addition, it was found that HG‑induced excessive activation of the mevalonate signaling pathway in VSMCs was suppressed following transfection with a miR‑125a mimic. Therefore, the present results suggest that decreased miR‑125a expression contributed to HG‑induced VSMC proliferation and migration via the upregulation of HMGCR expression. Thus, miR‑125a‑mediated regulation of the mevalonate signaling pathway may be associated with atherosclerosis.

Role of miR-92a-3p, oxidative stress, and p38MAPK/NF-κB pathway in rats with central venous catheter related thrombosis

BACKGROUND

miR-92a-3p and oxidative stress are reportedly associated with venous thrombosis. However, the role of miR-92a-3p and oxidative stress in catheter-related thrombosis (CRT) remains ambiguous. Herein, we studied the roles of miR-92a-3p, oxidative stress, and p38-mitogen-activated protein kinase/nuclear factor kappa-B (MAPK/NF-κB) pathway in CRT.

METHODS

Forty-five male rats were randomly and equally divided into control, sham operation, and CRT groups. The rats were sacrificed after 10 days. Reactive oxygen species (ROS), superoxide dismutase (SOD), and malondialdehyde (MDA) levels in the serum were determined by enzyme-linked immunosorbent assay (ELISA). The expression levels of miR-92a-3p, heme oxygenase-1 (HO-1), NF-κB p65, and p38 MAPK in the venous tissues were detected with quantitative polymerase chain reaction (qPCR) and Western blot.

RESULTS

Thrombosis was observed only in the CRT group. Compared with the levels in the control and sham operation groups, ROS and MDA significantly increased in the CRT group, but SOD significantly decreased. qPCR and Western blot results showed that miR-92a-3p, HO-1, p38 MAPK, and NF-κB p65 expression was significantly upregulated in the venous tissues of the CRT group. Moreover, miR-92a-3p was positively correlated with HO-1, which was positively correlated with p38 MAPK and NF-κB p65.

CONCLUSION

miR-92a-3p was correlated with oxidative stress in CRT. miR-92a-3p and oxidative stress contributed to endothelial dysfunction and simultaneously was associated with CRT.

miR-128-3p Is a Novel Regulator of Vascular Smooth Muscle Cell Phenotypic Switch and Vascular Diseases

RATIONALE

MicroRNAs (miRNAs, miRs) are small noncoding RNAs that modulate gene expression by negatively regulating translation of target genes. Although the role of several miRNAs in vascular smooth muscle cells (VSMCs) has been extensively characterized, the function of miRNA-128-3p (miR-128) is still unknown.

OBJECTIVE

To determine if miR-128 modulates VSMC phenotype and to define the underlying mechanisms.

METHODS AND RESULTS

We screened for miRNAs whose expression is modulated by an altered DNA methylation status in VSMCs, and among the hits, we selected miR-128. We found that miR-128 was expressed in various tissues, primary murine cells, and pathological murine and human vascular specimens. Through gain- and loss-of-function approaches, we determined that miR-128 affects VSMC proliferation, migration, differentiation, and contractility. The alterations of those properties were dependent upon epigenetic regulation of key VSMC differentiation genes; notably, Kruppel-like factor 4 was found to be a direct target of miR-128 and able to modulate the methylation status of the pivotal VSMC gene myosin heavy chain 11 (Myh11). Finally, in vivo lentiviral delivery of miR-128 prevented intimal hyperplasia in a mouse model of carotid restenosis without modifying vital cardiovascular parameters.

CONCLUSION

miR-128 is a critical modulator of VSMCs and is regulated by epigenetic modifications upon stress. Its modulation in the context of disease could be exploited for therapeutic purposes.

Mechanisms of Cardiovascular Disorders in Patients With Chronic Kidney Disease: A Process Related to Accelerated Senescence

Cardiovascular diseases (CVDs), especially those involving a systemic inflammatory process such as atherosclerosis, remain the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). CKD is a systemic condition affecting approximately 10% of the general population. The prevalence of CKD has increased over the past decades because of the aging of the population worldwide. Indeed, CVDs in patients with CKD constitute a premature form of CVD observed in the general population. Multiple studies indicate that patients with renal disease undergo accelerated aging, which precipitates the appearance of pathologies, including CVDs, usually associated with advanced age. In this review, we discuss several aspects that characterize CKD-associated CVDs, such as etiopathogenic elements that CKD patients share with the general population, changes in the cellular balance of reactive oxygen species (ROS), and the associated process of cellular senescence. Uremia-associated aging is linked with numerous changes at the cellular and molecular level. These changes are similar to those observed in the normal process of physiologic aging. We also discuss new perspectives in the study of CKD-associated CVDs and epigenetic alterations in intercellular signaling, mediated by microRNAs and/or extracellular vesicles (EVs), which promote vascular damage and subsequent development of CVD. Understanding the processes and factors involved in accelerated senescence and other abnormal intercellular signaling will identify new therapeutic targets and lead to improved methods of diagnosis and monitoring for patients with CKD-associated CVDs.

LncRNA CASC2 inhibits hypoxia-induced pulmonary artery smooth muscle cell proliferation and migration by regulating the miR-222/ING5 axis

Background

Pulmonary arterial hypertension (PAH) is often characterized by cell proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs). LncRNA cancer susceptibility candidate 2 (CASC2) has been revealed to be involved in PASMC injury in hypoxia-induced pulmonary hypertension. However, the exact molecular mechanisms whereby CASC2 regulates PASMC proliferation and migration are still incompletely understood.

Methods

The expression levels of CASC2, miR-222 and inhibitor of growth 5 (ING5) were measured using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot, respectively. Cell proliferation was analyzed by Cell Counting Kit-8 (CCK-8) assay. Wound healing assay was used to analyze cell migration ability. The relationship between miR-222 and CASC2 or ING5 was confirmed using bioinformatics analysis, luciferase reporter assay and RNA immunoprecipitation assay.

Results

CASC2 was down-regulated in hypoxia-induced PASMCs in a dose- and time-dependent manner. Functional experiments showed that CASC2 overexpression could reverse hypoxia-induced proliferation and migration of PASMCs. Bioinformatics analysis indicated that CASC2 acted as a competing endogenous RNA of miR-222, thereby regulating the expression of ING5, the downstream target of miR-222, in PASMCs. In addition, rescue assay suggested that the inhibition mediated by CASC2 of hypoxia-induced PASMC proliferation and migration could be attenuated by miR-222 inhibition or ING5 overexpression.

Conclusion

CASC2 attenuated hypoxia-induced PASMC proliferation and migration by regulating the miR-222/ING5 axis to prevent vascular remodeling and the development of PAH, providing a novel insight and therapeutic strategy for hypoxia-induced PAH.

Mechanisms of Arterial Stiffening: From Mechanotransduction to Epigenetics

Arterial stiffness is a major independent risk factor for cardiovascular complications causing isolated systolic hypertension and increased pulse pressure in the microvasculature of target organs. Stiffening of the arterial wall is determined by common mechanisms including reduced elastin/collagen ratio, production of elastin cross-linking, reactive oxygen species-induced inflammation, calcification, vascular smooth muscle cell stiffness, and endothelial dysfunction. This brief review will discuss current biological mechanisms by which other cardiovascular risk factors (eg, aging, hypertension, diabetes mellitus, and chronic kidney disease) cause arterial stiffness, with a particular focus on recent advances regarding nuclear mechanotransduction, mitochondrial oxidative stress, metabolism and dyslipidemia, genome mutations, and epigenetics. Targeting these different molecular pathways at different time of cardiovascular risk factor exposure may be a novel approach for discovering drugs to reduce arterial stiffening without affecting artery strength and normal remodeling.

Roles and Functions of Exosomal Non-coding RNAs in Vascular Aging

Aging is a progressive loss of physiological integrity and functionality process which increases susceptibility and mortality to diseases. Vascular aging is a specific type of organic aging. The structure and function changes of endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are the main cause of vascular aging, which could influence the threshold, process, and severity of vascular related diseases. Accumulating evidences demonstrate that exosomes serve as novel intercellular information communicator between cell to cell by delivering variety biologically active cargos, especially exosomal non-coding RNAs (ncRNAs), which are associated with most of aging-related biological and functional disorders. In this review, we will summerize the emerging roles and mechanisms of exosomal ncRNAs in vascular aging and vascular aging related diseases, focusing on the role of exosomal miRNAs and lncRNAs in regulating the functions of ECs and VSMCs. Moreover, the relationship between the ECs and VSMCs linked by exosomes, the potential diagnostic and therapeutic application of exosomes in vascular aging and the clinical evaluation and treatment of vascular aging and vascular aging related diseases will also be discussed.

Non-coding RNAs: key regulators of smooth muscle cell fate in vascular disease

The vascular smooth muscle cell (SMC) is one of the most plastic cells in the body. Understanding how non-coding RNAs (ncRNAs) regulate SMC cell-fate decision making in the vasculature has significantly enhanced our understanding of disease development, and opened up exciting new avenues for potential therapeutic applications. Recent studies on SMC physiology have in addition challenged our traditional view on their role and contribution to vascular disease, mainly in the setting of atherosclerosis as well as aneurysm disease, and restenosis after angioplasties. The impact of SMC behaviour on vascular disease is now recognized to be context dependent; SMC proliferation and migration can be harmful or beneficial, whereas their apoptosis, senescence, and switching into a more macrophage-like phenotype can promote inflammation and disease progression. This is in particular true for atherosclerosis-related diseases, where proliferation of SMCs was believed to promote lesion formation, but may also prevent plaque rupture by stabilizing the fibrous cap. Based on newer findings of genetic lineage tracing studies, it was revealed that SMC phenotypic switching can result in less-differentiated forms that lack classical SMC markers while exhibiting functions more related to macrophage-like cells. This switching can directly promote atherogenesis. The aim of this current review is to summarize and discuss how ncRNAs (mainly microRNAs and long ncRNAs) are involved in SMC plasticity, and how they directly affect vascular disease development and progression. Finally, we want to critically assess where potential future therapies could be useful to influence the burden of vascular diseases.

Smooth muscle cell fate and plasticity in atherosclerosis

Current knowledge suggests that intimal smooth muscle cells (SMCs) in native atherosclerotic plaque derive mainly from the medial arterial layer. During this process, SMCs undergo complex structural and functional changes giving rise to a broad spectrum of phenotypes. Classically, intimal SMCs are described as dedifferentiated/synthetic SMCs, a phenotype characterized by reduced expression of contractile proteins. Intimal SMCs are considered to have a beneficial role by contributing to the fibrous cap and thereby stabilizing atherosclerotic plaque. However, intimal SMCs can lose their properties to such an extent that they become hard to identify, contribute significantly to the foam cell population, and acquire inflammatory-like cell features. This review highlights mechanisms of SMC plasticity in different stages of native atherosclerotic plaque formation, their potential for monoclonal or oligoclonal expansion, as well as recent findings demonstrating the underestimated deleterious role of SMCs in this disease.

miR‑132 inhibits high glucose‑induced vascular smooth muscle cell proliferation and migration by targeting E2F5

The dysregulated behavior of vascular smooth muscle cells (VSMCs) serves an important role in the pathogenesis of cardiovascular diseases in diabetes. The present study aimed to investigate the effects of microRNA (miR)‑132 on the proliferation and migration of VSMCs under high glucose conditions to mimic diabetes. We observed that the expression of miR‑132 was significantly decreased and that of E2F transcription factor 5 (E2F5) was upregulated in high glucose (HG)‑treated VSMCs or those obtained from diabetic rats. A dual luciferase reporter gene assay revealed that miR‑132 could specifically bind to the 3'‑untranslated region of E2F5 and significantly suppress the luciferase activity. The proliferation and migration of diabetic rat or HG‑treated VSMCs were increased compared with non‑diabetic rat VSMCs and those under normal glucose conditions. Upregulation of miR‑132 significantly inhibited the proliferation and migration of diabetic rat VSMCs; similar effects were observed following E2F5 downregulation. The inhibitory effects of miR‑132 on the proliferation and migration of HG‑treated VSMCs could be reversed by E2F5 overexpression. In conclusion, miR‑132 was proposed to inhibit the proliferation and migration of diabetic rat or high‑glucose‑treated VSMCs by targeting E2F5. The findings of the present study suggested that increasing the expression of miR‑132 may serve as a novel therapeutic approach to inhibit the progression of cardiovascular disease in diabetes.

Smooth muscle cell-driven vascular diseases and molecular mechanisms of VSMC plasticity

Vascular smooth muscle cells (VSMCs) are the major cell type in blood vessels. Unlike many other mature cell types in the adult body, VSMC do not terminally differentiate but retain a remarkable plasticity. Fully differentiated medial VSMCs of mature vessels maintain quiescence and express a range of genes and proteins important for contraction/dilation, which allows them to control systemic and local pressure through the regulation of vascular tone. In response to vascular injury or alterations in local environmental cues, differentiated/contractile VSMCs are capable of switching to a dedifferentiated phenotype characterized by increased proliferation, migration and extracellular matrix synthesis in concert with decreased expression of contractile markers. Imbalanced VSMC plasticity results in maladaptive phenotype alterations that ultimately lead to progression of a variety of VSMC-driven vascular diseases. The nature, extent and consequences of dysregulated VSMC phenotype alterations are diverse, reflecting the numerous environmental cues (e.g. biochemical factors, extracellular matrix components, physical) that prompt VSMC phenotype switching. In spite of decades of efforts to understand cues and processes that normally control VSMC differentiation and their disruption in VSMC-driven disease states, the crucial molecular mechanisms and signalling pathways that shape the VSMC phenotype programme have still not yet been precisely elucidated. In this article we introduce the physiological functions of vascular smooth muscle/VSMCs, outline VSMC-driven cardiovascular diseases and the concept of VSMC phenotype switching, and review molecular mechanisms that play crucial roles in the regulation of VSMC phenotypic plasticity.

MicroRNA-21 Knockout Exacerbates Angiotensin II–Induced Thoracic Aortic Aneurysm and Dissection in Mice With Abnormal Transforming Growth Factor-β–SMAD3 Signaling

Objective—

Thoracic aortic aneurysm and dissection (TAAD) are severe vascular conditions. Dysfunctional transforming growth factor-β (TGF-β) signaling in vascular smooth muscle cells and elevated angiotensin II (AngII) levels are implicated in the development of TAAD. In this study, we investigated whether these 2 factors lead to TAAD in a mouse model and explored the possibility of using microRNA-21 ( miR-21 ) for the treatment of TAAD.

Approach and Results—

TAAD was developed in Smad3 (mothers against decapentaplegic homolog 3) heterozygous (S3 +/− ) mice infused with AngII. We found that p-ERK (phosphorylated extracellular regulated protein kinases)– and p-JNK (phosphorylated c-Jun N-terminal kinase)–associated miR-21 was higher in TAAD lesions. We hypothesize that downregulation of miR-21 mitigate TAAD formation. However, Smad3 +/− :miR-21 −/− (S3 +/− 21 −/− ) mice exhibited conspicuous TAAD formation after AngII infusion. The vascular wall was dilated, and aortic rupture occurred within 23 days during AngII infusion. We then examined canonical and noncanonical TGF-β signaling and found that miR-21 knockout in S3 +/− mice increased SMAD7 and suppressed canonical TGF-β signaling. Vascular smooth muscle cells lacking TGF-β signals tended to switch from a contractile to a synthetic phenotype. The silencing of Smad7 with lentivirus prevented AngII-induced TAAD formation in S3 +/− 21 −/− mice.

Conclusions—

Our study demonstrated that miR-21 knockout exacerbated AngII-induced TAAD formation in mice, which was associated with TGF-β signaling dysfunction. Therapeutic strategies targeting TAAD should consider unexpected side effects associated with alterations in TGF-β signaling.

MiR-135a Promotes Inflammatory Responses of Vascular Smooth Muscle Cells From db/db Mice via Downregulation of FOXO1

It has been shown that microRNAs (miRNAs) greatly affect the functions of vascular smooth muscle cells (VSMC), but the effects of mRNAs under diabetic conditions remain unclear.Using a model of diabetic db/db mice, we studied the functions of microRNA-135a (miR-135a) during VSMC dysfunction.Compared to control WT mice, miR-135a expression in VSMC was significantly increased while the level of forkhead box O1 (FOXO1) protein decreased significantly. After transfecting miR-135a mimics into VSMC, the expression of FOXO1 was decreased, while cyclooxygenase-2 (COX-2) and monocyte chemoattractant protein-1 (MCP-1) expression levels were increased, thus promoting the interaction between monocytes and WT VSMC. On the other hand, transfection of an miR-135a inhibitor reversed the activated interaction between monocytes and db/db VSMC. The pro-inflammatory responses could also be enhanced by using siRNAs to silence the FOXO1 gene in WT VSMC, suggesting a negative regulatory role of FOXO1. FOXO1 siRNAs and miR-135a mimics could both enhance the transcriptional activity of COX-2 promoter. Using chromatin immunoprecipitation, we found that in db/db VSMC, the occupancy in promoter regions of inflammatory genes by FOXO1 was reduced.miR-135a increased the inflammatory responses of VSMC involved in complications of vascular diseases by downregulating the expression of FOXO1.

Type 2 Diabetes Mellitus and Cardiovascular Disease: Genetic and Epigenetic Links

Type 2 diabetes mellitus (DM) is a common metabolic disorder predisposing to diabetic cardiomyopathy and atherosclerotic cardiovascular disease (CVD), which could lead to heart failure through a variety of mechanisms, including myocardial infarction and chronic pressure overload. Pathogenetic mechanisms, mainly linked to hyperglycemia and chronic sustained hyperinsulinemia, include changes in metabolic profiles, intracellular signaling pathways, energy production, redox status, increased susceptibility to ischemia, and extracellular matrix remodeling. The close relationship between type 2 DM and CVD has led to the common soil hypothesis, postulating that both conditions share common genetic and environmental factors influencing this association. However, although the common risk factors of both CVD and type 2 DM, such as obesity, insulin resistance, dyslipidemia, inflammation, and thrombophilia, can be identified in the majority of affected patients, less is known about how these factors influence both conditions, so that efforts are still needed for a more comprehensive understanding of this relationship. The genetic, epigenetic, and environmental backgrounds of both type 2 DM and CVD have been more recently studied and updated. However, the underlying pathogenetic mechanisms have seldom been investigated within the broader shared background, but rather studied in the specific context of type 2 DM or CVD, separately. As the precise pathophysiological links between type 2 DM and CVD are not entirely understood and many aspects still require elucidation, an integrated description of the genetic, epigenetic, and environmental influences involved in the concomitant development of both diseases is of paramount importance to shed new light on the interlinks between type 2 DM and CVD. This review addresses the current knowledge of overlapping genetic and epigenetic aspects in type 2 DM and CVD, including microRNAs and long non-coding RNAs, whose abnormal regulation has been implicated in both disease conditions, either etiologically or as cause for their progression. Understanding the links between these disorders may help to drive future research toward an integrated pathophysiological approach and to provide future directions in the field.

Cardiovascular Risk Factors and Markers

Cardiovascular risk is assessed for the prediction and appropriate management of patients using collections of identified risk markers obtained from clinical questionnaire information, concentrations of certain blood molecules (e.g., N-terminal proB-type natriuretic peptide fragment and soluble receptors of tumor-necrosis factor-α and interleukin-2), imaging data using various modalities, and electrocardiographic variables, in addition to traditional risk factors.

Vascular Smooth Muscle Cells and Arterial Stiffening: Relevance in Development, Aging, and Disease

The cushioning function of large arteries encompasses distension during systole and recoil during diastole which transforms pulsatile flow into a steady flow in the microcirculation. Arterial stiffness, the inverse of distensibility, has been implicated in various etiologies of chronic common and monogenic cardiovascular diseases and is a major cause of morbidity and mortality globally. The first components that contribute to arterial stiffening are extracellular matrix (ECM) proteins that support the mechanical load, while the second important components are vascular smooth muscle cells (VSMCs), which not only regulate actomyosin interactions for contraction but mediate also mechanotransduction in cell-ECM homeostasis. Eventually, VSMC plasticity and signaling in both conductance and resistance arteries are highly relevant to the physiology of normal and early vascular aging. This review summarizes current concepts of central pressure and tensile pulsatile circumferential stress as key mechanical determinants of arterial wall remodeling, cell-ECM interactions depending mainly on the architecture of cytoskeletal proteins and focal adhesion, the large/small arteries cross-talk that gives rise to target organ damage, and inflammatory pathways leading to calcification or atherosclerosis. We further speculate on the contribution of cellular stiffness along the arterial tree to vascular wall stiffness. In addition, this review provides the latest advances in the identification of gene variants affecting arterial stiffening. Now that important hemodynamic and molecular mechanisms of arterial stiffness have been elucidated, and the complex interplay between ECM, cells, and sensors identified, further research should study their potential to halt or to reverse the development of arterial stiffness.

MicroRNAs and Cardiovascular Disease in Diabetes Mellitus

Cardiovascular disease (CVD) is the major macrovascular complication of diabetes mellitus. Recently, although CVD morbidity and mortality have decreased as a result of comprehensive control of CVD risk factors, CVD remains the leading cause of death of patients with diabetes in many countries, indicating the potential underlying pathophysiological mechanisms. MicroRNAs are a class of noncoding, single-stranded RNA molecules that are involved in β-cell function, insulin secretion, insulin resistance, skeletal muscle, and adipose tissue and which play an important role in glucose homeostasis and the pathogenesis of diabetic complications. Here, we review recent progress in research on microRNAs in endothelial cell and vascular smooth muscle cell dysfunction, macrophage and platelet activation, lipid metabolism abnormality, and cardiomyocyte repolarization in diabetes mellitus. We also review the progress of microRNAs as potential biomarkers and therapeutic targets of CVD in patients with diabetes.

Killing Me Unsoftly: Causes and Mechanisms of Arterial Stiffness

The aorta is a blood vessel that provides a low-resistance path for blood flow directed from the heart to peripheral organs and tissues. However, the aorta has another central hemodynamic function, whereby the elastic nature of the aortic wall provides a significant biomechanical buffering capacity complementing the pulsatile cardiac blood flow, and this is often referred to as Windkessel function. Stiffening of the arterial wall leads to fundamental alterations in central hemodynamics, with widespread detrimental implications for organ function. In this Recent Highlights article, we describe recent contributions in ATVB that have highlighted the novel mechanisms and consequences of arterial stiffness and the clinical conditions in which arterial stiffness occurs, with a focus on advancements in the field.

Function, Role, and Clinical Application of MicroRNAs in Vascular Aging

Vascular aging, a specific type of organic aging, is related to age-dependent changes in the vasculature, including atherosclerotic plaques, arterial stiffness, fibrosis, and increased intimal thickening. Vascular aging could influence the threshold, process, and severity of various cardiovascular diseases, thus making it one of the most important risk factors in the high mortality of cardiovascular diseases. As endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are the main cell biological basis of these pathology changes of the vasculature, the structure and function of ECs and VSMCs play a key role in vascular aging. MicroRNAs (miRNAs), small noncoding RNAs, have been shown to regulate the expression of multiple messenger RNAs (mRNAs) posttranscriptionally, contributing to many crucial aspects of cell biology. Recently, miRNAs with functions associated with aging or aging-related diseases have been studied. In this review, we will summarize the reported role of miRNAs in the process of vascular aging with special emphasis on EC and VSMC functions. In addition, the potential application of miRNAs to clinical practice for the diagnosis and treatment of cardiovascular diseases will also be discussed.

Aging-associated changes in microRNA expression profile of internal anal sphincter smooth muscle: Role of microRNA-133a

A comprehensive genomic and proteomic, computational, and physiological approach was employed to examine the (previously unexplored) role of microRNAs (miRNAs) as regulators of internal anal sphincter (IAS) smooth muscle contractile phenotype and basal tone. miRNA profiling, genome-wide expression, validation, and network analyses were employed to assess changes in mRNA and miRNA expression in IAS smooth muscles from young vs. aging rats. Multiple miRNAs, including rno-miR-1, rno-miR-340-5p, rno-miR-185, rno-miR-199a-3p, rno-miR-200c, rno-miR-200b, rno-miR-31, rno-miR-133a, and rno-miR-206, were found to be upregulated in aging IAS. qPCR confirmed the upregulated expression of these miRNAs and downregulation of multiple, predicted targets (Eln, Col3a1, Col1a1, Zeb2, Myocd, Srf, Smad1, Smad2, Rhoa/Rock2, Fn1, Tagln v2, Klf4, and Acta2) involved in regulation of smooth muscle contractility. Subsequent studies demonstrated an aging-associated increase in the expression of miR-133a, corresponding decreases in RhoA, ROCK2, MYOCD, SRF, and SM22α protein expression, RhoA-signaling, and a decrease in basal and agonist [U-46619 (thromboxane A₂ analog)]-induced increase in the IAS tone. Moreover, in vitro transfection of miR-133a caused a dose-dependent increase of IAS tone in strips, which was reversed by anti-miR-133a. Last, in vivo perianal injection of anti-miR-133a reversed the loss of IAS tone associated with age. This work establishes the important regulatory effect of miRNA-133a on basal and agonist-stimulated IAS tone. Moreover, reversal of age-associated loss of tone via anti-miR delivery strongly implicates miR dysregulation as a causal factor in the aging-associated decrease in IAS tone and suggests that miR-133a is a feasible therapeutic target in aging-associated rectoanal incontinence.

Role of noncoding RNA in vascular remodelling

PURPOSE OF REVIEW

Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are becoming fundamentally important in the pathophysiology relating to injury-induced vascular remodelling. We highlight recent studies that demonstrate the involvement of ncRNAs in vein graft disease, in in-stent restenosis and in pulmonary arterial hypertension, with a particular focus on endothelial cell and vascular smooth muscle cell function. We also briefly discuss the emerging role of exosomal-derived ncRNAs and how this mechanism impacts on vascular function.

RECENT FINDINGS

ncRNAs have been described as novel regulators in the pathophysiology of vascular injury, inflammation, and vessel wall remodelling. In particular, several studies have demonstrated that manipulation of miRNAs can reduce the burden of pathological vascular remodelling. Such studies have also shown that exosomal miRNA-mediated, cell-to-cell communication between endothelial cells and vascular smooth muscle cells is critical in the disease process. In addition to miRNAs, lncRNAs are emerging as regulators of vascular function in health and disease. Although lncRNAs are complex in both their sheer numbers and mechanisms of action, identifying their contribution to vascular disease is essential.

SUMMARY

Given the important roles of ncRNAs in vascular injury and remodelling together will their capacity for cell-to-cell communication, manipulating ncRNA might provide novel therapeutic interventions.

Mechanisms of Vascular Smooth Muscle Contraction and the Basis for Pharmacologic Treatment of Smooth Muscle Disorders

The smooth muscle cell directly drives the contraction of the vascular wall and hence regulates the size of the blood vessel lumen. We review here the current understanding of the molecular mechanisms by which agonists, therapeutics, and diseases regulate contractility of the vascular smooth muscle cell and we place this within the context of whole body function. We also discuss the implications for personalized medicine and highlight specific potential target molecules that may provide opportunities for the future development of new therapeutics to regulate vascular function.

Regulation of Vascular Smooth Muscle Cell Dysfunction Under Diabetic Conditions by miR-504

OBJECTIVE

Diabetes mellitus accelerates proatherogenic and proinflammatory phenotype of vascular smooth muscle cell (VSMC) associated with vascular complications. Evidence shows that microRNAs (miRNAs) play key roles in VSMC functions, but their role under diabetic conditions is unclear. We profiled miRNAs in VSMC from diabetic mice and examined their role in VSMC dysfunction.

APPROACH AND RESULTS

High throughput small RNA-sequencing identified 135 differentially expressed miRNAs in VSMC from type 2 diabetic db/db mice (db/dbVSMC) versus nondiabetic db/+ mice. Several of these miRNAs were known to regulate VSMC functions. We further focused on miR-504, because it was highly upregulated in db/dbVSMC, and its function in VSMC is unknown. miR-504 and its host gene Fgf13 were significantly increased in db/dbVSMC and in aortas from db/db mice. Bioinformatics analysis predicted that miR-504 targets including signaling adaptor Grb10 and transcription factor Egr2 could regulate growth factor signaling. We experimentally validated Grb10 and Egr2 as novel targets of miR-504. Overexpression of miR-504 in VSMC inhibited contractile genes and enhanced extracellular signal-regulated kinase 1/2 activation, proliferation, and migration. These effects were blocked by miR-504 inhibitors. Grb10 knockdown mimicked miR-504 functions and increased inflammatory genes. Egr2 knockdown-inhibited anti-inflammatory Socs1 and increased proinflammatory genes. Furthermore, high glucose and palmitic acid upregulated miR-504 and inflammatory genes, but downregulated Grb10.

CONCLUSIONS

Diabetes mellitus misregulates several miRNAs including miR-504 that can promote VSMC dysfunction. Because changes in many of these miRNAs are sustained in diabetic VSMC even after in vitro culture, they may be involved in metabolic memory of vascular complications. Targeting such mechanisms could offer novel therapeutic strategies for diabetic complications.

MicroRNA-221 sponge therapy attenuates neointimal hyperplasia and improves blood flows in vein grafts

BACKGROUND

Vein graft failure due to neointimal hyperplasia remains an important and unresolved problem of cardiovascular surgery. MicroRNA-221 (miR-221) has been shown to play a major role in regulating vascular smooth muscle cell (VSMC) proliferation and phenotype transformation. Thus, the purpose of this study is to determine whether adenovirus mediated miR-221 sponge gene therapy could inhibit vein graft neointimal hyperplasia.

METHODS

Adenovirus encoding miR-221 sponge (Ad-miR-221-SP) was used to inhibit VSMC proliferation in vitro and neointimal formation in vivo. Expression of miRNA-221 was evaluated in cultured VSMC and in rat vein graft models following transduction with Ad-miR-221-SP, Ad-Control-SP (without miR-221 antisense binding sites), or Ad-GFP (control). To accelerate the transfer of miR-221 sponge gene to the vein grafts, 20% poloxamer F-127 gel was used to extend virus contact time and 0.25% trypsin to increase virus penetration.

RESULTS

miR-221 sponges can significantly decrease the expression of miR-221 and proliferation in cultured VSMC. Cellular proliferation rates were significantly reduced in miR-221 sponge treated grafts as compared with controls at 6 weeks after bypass surgery (19.8% versus 43.6%, P=0.0028). miR-221 sponge gene transfer reduced the neointimal area (210.75 ± 24.13 versus 67.01 ± 12.02, P<0.0001), neointimal thickness (171.86 ± 27.87 versus 64.13 ± 16.23, P<0.0001) and neointima/media ratio (0.74 ± 0.21 versus 1.95 ± 0.25, P<0.0001) in vein grafts versus controls. miR-21 sponge treatment was also improved hemodynamics in vein grafts. We have further identified that p27 (Kip1) is a potential target gene of miR-221 in vein grafts.

CONCLUSION

miR-221 sponge therapy can significantly reduce miR-221 activity and inhibit neointimal hyperplasia in vein grafts. Locally adventitial delivery of adenoviruses mediated miRNA sponges may be promising gene therapies to prevent vein graft failure.

Functional Long Non-coding RNAs in Vascular Smooth Muscle Cells

Increasing evidence shows that long non-coding RNAs (lncRNAs) are not "transcriptional noise" but function in a myriad of biological processes. As such, this rapidly growing class of RNAs is important in both development and disease. Vascular smooth muscle cells are integral cells of the blood vessel wall. They are responsible for relaxation and contraction of the blood vessel and respond to hemodynamic as well as environmental signals to regulate blood pressure. Pathophysiological changes to these cells such as hyperproliferation, hypertrophy, migration, and inflammation contribute to cardiovascular diseases (CVDs) such as restenosis, hypertension, and atherosclerosis. Understanding the molecular mechanisms involved in these pathophysiological changes to VSMCs is paramount to developing therapeutic treatments for various cardiovascular disorders. Recent studies have shown that lncRNAs are key players in the regulation of VSMC functions and phenotype and, perhaps also, in the development of VSMC-related diseases. This chapter describes our current understanding of the functions of lncRNAs in VSMCs. It highlights the emerging role of lncRNAs in VSMC proliferation and apoptosis, their role in contractile and migratory phenotype of VSMCs, and their potential role in VSMC disease states.