Vascular Smooth Muscle Cell Function Research Articles

Understanding the Relationship Between Vascular Smooth Muscle Cell Function and the Efficacy of Acupuncture in Treating Cerebral Ischemic Stroke: A Preclinical Meta-Analysis and Systematic Review.

Cerebral blood flow and vascular structures serve as the fundamental components of brain metabolism and circulation. Acupuncture, an alternative and complementary medical approach, has demonstrated efficacy in treating cerebral ischemic stroke (CIS). Nevertheless, the mechanisms underlying the impact of acupuncture on vascular smooth muscle cell (VSMC) function remain uncertain. The objective of this systematic review and meta-analysis is to assess the alterations in VSMC function following acupuncture stimulation in CIS models. The databases PubMed, Web of Science, SCOPUS, and EMBASE were queried until November 2022 using a predetermined search strategy. The FORMAT BY SYRCLE guidelines were adhered to, and the risk of bias of the included studies was evaluated using the Risk of Bias tool developed by the Systematic Review Centre for Laboratory Animal Experimentation. The random-effects model was employed to estimate the standardized mean difference (SMD). Eighteen articles are included in this review. Acupuncture showed significant positive effects on the region cerebral blood flow (SMD=8.15 [95% CI, 4.52 to 11.78]) and neurological deficiency (SMD=-3.75 [95% CI, -5.54 to -1.97]). Descriptive analysis showed a probable mechanism of acupuncture stimulation in CIS rats related to VSMC function. Limitations and publication bias were presented in the studies. In this systematic review and meta-analysis, our findings indicate that acupuncture stimulation has the potential to improve regional cerebral blood flow and alleviate neurological deficits, possibly by regulating VSMC function. However, it is important to exercise caution when interpreting these results due to the limitations of animal experimental design and methodological quality.

SGLT2 Inhibitors Extra Glycemic Potential: A Possible Novel Approach to the Prevention of Atherosclerotic Events

Introduction: Cardiovascular diseases are a major global health concern, with atherosclerosis being a significant contributor. Diabetes mellitus is a well-known risk factor for atherosclerosis, and SGLT2 inhibitors are more effective in reducing cardiovascular disease and mortality compared to other antihyperglycemic agents in patients with type 2 diabetes. Endothelial dysfunction, VSMC phenotypic alterations, inflammation, autophagy, oxidative stress, signaling hormones and dysbiosis are crucial factors and predictors of atherosclerosis and other cardiovascular events. SGLT2 inhibitors have been shown to alleviate these components in atherosclerotic models. Material and Methods: To proceed we analyzed and took into account all publications, including clinical trials, animal studies, in vitro observations, reviews, and meta-analyses from various scientific databases. Results: Evidently, SGLT2i attenuate the progression of atherosclerosis by repressing vascular inflammation, oxidative stress, endothelial dysfunction, mitigating vascular smooth muscle cells function, impairing foam cell formation, preventing platelet activation and restoration of normal autophagic function. Conclusion: Based on these findings, it can be inferred that SGLT2 inhibitors exhibit anti-atherosclerotic characteristics and may have positive implications for the management of atherosclerosis, particularly in individuals with diabetic complications.

LncRNA CARMN inhibits abdominal aortic aneurysm formation and vascular smooth muscle cell phenotypic transformation by interacting with SRF

Phenotypic transformation of vascular smooth muscle cells (VSMCs) plays a crucial role in abdominal aortic aneurysm (AAA) formation. CARMN, a highly conserved, VSMC-enriched long noncoding RNA (lncRNA), is integral in orchestrating various vascular pathologies by modulating the phenotypic dynamics of VSMCs. The influence of CARMN on AAA formation, particularly its mechanisms, remains enigmatic. Our research, employing single-cell and bulk RNA sequencing, has uncovered a significant suppression of CARMN in AAA specimens, which correlates strongly with the contractile function of VSMCs. This reduced expression of CARMN was consistent in both 7- and 14-day porcine pancreatic elastase (PPE)-induced mouse models of AAA and in human clinical cases. Functional analyses disclosed that the diminution of CARMN exacerbated PPE-precipitated AAA formation, whereas its augmentation conferred protection against such formation. Mechanistically, we found CARMN's capacity to bind with SRF, thereby amplifying its role in driving the transcription of VSMC marker genes. In addition, our findings indicate an enhancement in CAMRN transcription, facilitated by the binding of NRF2 to its promoter region. Our study indicated that CARMN plays a protective role in preventing AAA formation and restrains the phenotypic transformation of VSMC through its interaction with SRF. Additionally, we observed that the expression of CARMN is augmented by NRF2 binding to its promoter region. These findings suggest the potential of CARMN as a viable therapeutic target in the treatment of AAA.Graphical abstract

Oxidized phospholipid POVPC contributes to vascular calcification by triggering ferroptosis of vascular smooth muscle cells.

Vascular calcification is an actively regulated biological process resembling bone formation, and osteogenic differentiation of vascular smooth muscle cells (VSMCs) plays a crucial role in this process. 1-Palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3-phosphocholine (POVPC), an oxidized phospholipid, is found in atherosclerotic plaques and has been shown to induce oxidative stress. However, the effects of POVPC on osteogenic differentiation and calcification of VSMCs have yet to be studied. In the present study, we investigated the role of POVPC in vascular calcification using invitro and exvivo models. POVPC increased mineralization of VSMCs and arterial rings, as shown by alizarin red staining. In addition, POVPC treatment increased expression of osteogenic markers Runx2 and BMP2, indicating that POVPC promotes osteogenic transition of VSMCs. Moreover, POVPC increased oxidative stress and impaired mitochondria function of VSMCs, as shown by increased ROS levels, impairment of mitochondrial membrane potential, and decreased ATP levels. Notably, ferroptosis triggered by POVPC was confirmed by increased levels of intracellular ROS, lipid ROS, and MDA, which were decreased by ferrostatin-1, a ferroptosis inhibitor. Furthermore, ferrostatin-1 attenuated POVPC-induced calcification of VSMCs. Taken together, our study for the first time demonstrates that POVPC promotes vascular calcification via activation of VSMC ferroptosis. Reducing the levels of POVPC or inhibiting ferroptosis might provide a novel strategy to treat vascular calcification.

Spaceflight effects on human vascular smooth muscle cell phenotype and function

The cardiovascular system is strongly impacted by the hazards of spaceflight. Astronauts spending steadily increasing lengths of time in microgravity are subject to cardiovascular deconditioning resulting in loss of vascular tone, reduced total blood volume, and diminished cardiac output. Appreciating the mechanisms by which the cells of the vasculature are altered during spaceflight will be integral to understanding and combating these deleterious effects as the human presence in space advances. In this study, we performed RNA-Seq analysis coupled with review by QIAGEN Ingenuity Pathway Analysis software on human aortic smooth muscle cells (HASMCs) cultured for 3 days in microgravity and aboard the International Space Station to assess the transcriptomic changes that occur during spaceflight. The results of our RNA-Seq analysis show that SMCs undergo a wide range of transcriptional alteration while in space, significantly affecting 4422 genes. SMCs largely down-regulate markers of the contractile, synthetic, and osteogenic phenotypes including smooth muscle alpha actin (αSMA), matrix metalloproteinases (MMPs), and bone morphogenic proteins (BMPs). Additionally, components of several cellular signaling pathways were strongly impacted including the STAT3, NFκB, PI3K/AKT, HIF1α, and Endothelin pathways. This study highlights the significant changes in transcriptional behavior SMCs exhibit during spaceflight and puts these changes in context to better understand vascular function in space.

Enhancer of zeste homolog 2 facilitates phenotypic transition of vascular smooth muscle cells leading to aortic aneurysm/dissection.

Thoracic aortic aneurysms (TAAs) are a major cause of death owing to weaker blood vessel walls and higher rupture rates in affected individuals. Vascular smooth muscle cells (VSMCs) are the predominant cell type within the aortic wall and their dysregulation may contribute to TAA progression. Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, is involved in several pathological processes; however, the biological functions and mechanisms underlying VSMC phenotype transition and vascular intimal hyperplasia remain unclear. The present study aimed to determine the involvement of EZH2 in mediating VSMC function in the development of TAAs. The expression of EZH2 was revealed to be elevated in patients with thoracic aortic dissection and TAA mouse model through western blotting and reverse transcription-quantitative PCR experiments. Subsequently, a mouse model was established using β-aminopropionitrile. In vitro, EdU labeling, Transwell assay, wound healing assay and hematoxylin-eosin staining revealed that knocking down the Ezh2 gene could reduce the proliferation, invasion, migration, and calcification of mouse primary aortic smooth muscle cells. Flow cytometry analysis found that EZH2 deficiency increased cell apoptosis. Depletion of Ezh2 in mouse primary aortic VSMCs promoted the transformation of VSMCs from a synthetic to a contractile phenotype. Using RNA-sequencing analysis, it was demonstrated that Ezh2 regulated a group of genes, including integrin β3 (Itgb3), which are critically involved in the extracellular matrix signaling pathway. qChIP found Ezh2 occupies the Itgb3 promoter, thereby suppressing the expression of Itgb3. Ezh2 promotes the invasion and calcification of VSMCs, and this promoting effect is partially reversed by co-knocking down Itgb3. In conclusion, the present study identified a previously unrecognized EZH2-ITGB3 regulatory axis and thus provides novel mechanistic insights into the pathophysiological function of EZH2. EZH2 may thus serve as a potential target for the management of TAAs.

PCSK9 increases vulnerability of carotid plaque by promoting mitochondrial dysfunction and apoptosis of vascular smooth muscle cells.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been recognized as a novel lipid-lowing target. Recent clinical studies suggested the value of inhibiting PCSK9 in decreasing the vulnerability of coronary plaques. However, the evidence of PCSK9-regulated evolution of unstable carotid plaques is unclear, which has limited the use of PCSK9 inhibitor in carotid plaques. This study aimed to determine the effect and molecular mechanisms of PCSK9 on vulnerability of carotid plaques, to provide potential therapeutic targets for stabilizing carotid plaques. The expression of PCSK9 in stable and unstable carotid plaques were examined in tissue and plasma. Human aortic vascular smooth muscle cells (VSMCs) and carotid VSMCs were employed to transfect lentivirus for overexpression and knockdown of PCSK9, respectively. Morphological and functional changes of mitochondria were observed by live-cell imaging. Cell apoptosis was evaluated by propidium iodide staining. RNA-sequencing and biological examinations were performed to explore and validate the underlying mechanisms. Truncated plasmids were employed to identify the functional domain of PCSK9 in regulation of VSMCs' mitochondrial morphology, function and apoptosis. Clinically, PCSK9 was closely related with vulnerability of human carotid plaques. Increased expression of PCSK9 in human VSMCs was accompanied by higher level of apoptosis. At subcellular level of VSMCs, the morphology of mitochondria was shifted toward the fission state, followed by mitochondrial dysfunction. Inhibition of p38 MAPK activation partially rescued the above morphological and behavioral changes caused by PCSK9. Furthermore, inhibiting of dynamin-related protein 1 (DRP1) attenuated PCSK9-related mitochondrial dysfunction and cell apoptosis. The 1-149aa domain of PCSK9 protein was essential to achieve functional regulation to VSMCs. Our findings demonstrated that PCSK9 induced morphology-related mitochondrial dysfunction and apoptosis of VSMCs, which may be related to increased vulnerability of carotid plaque.

Ferrostatin-1 inhibits ferroptosis of vascular smooth muscle cells and alleviates abdominal aortic aneurysm formation through activating the SLC7A11/GPX4 axis.

Ferroptosis, a type of iron-catalyzed necrosis, is responsible for vascular smooth muscle cell (VSMC) death and serves as a potential therapeutic target for alleviating aortic aneurysm. Here, our study explored the underlying mechanism of ferroptosis affecting VSMC functions and the resultant formation of AAA using its inhibitor Ferrostatin-1 (Fer-1). Microarray-based gene expression profiling was employed to identify differentially expressed genes related to AAA and ferroptosis. An AAA model was established by angiotensin II (Ang II) induction in apolipoprotein E-knockout (ApoE-/- ) mice, followed by injection of Fer-1 and RSL-3 (ferroptosis inducer). Then, the role of Fer-1 and RSL-3 in the ferroptosis of VSMCs and AAA formation was analyzed in Ang II-induced mice. Primary mouse VSMCs were cultured invitro and treated with Ang II, Fer-1, sh-SLC7A11, or sh-GPX4 to assess the effect of Fer-1 via the SLC7A11/GPX axis. Bioinformatics analysis revealed that GPX4 was involved in the fibrosis formation of AAA, and there was an interaction between SLC7A11 and GPX4. Invitro assays showed that Fer-1 alleviated Ang II-induced ferroptosis of VSMCs and retard the consequent AAA formation. The mechanism was associated with activation of the SLC7A11/GPX4 pathway. Silencing of SLC7A11 or GPX4 could inhibit the ameliorating effect of Fer-1 on the ferroptosis of VSMCs. Invivo animal studies further demonstrated that Fer-1 inhibited Ang II-induced ferroptosis and vessel wall structural abnormalities in AAA mouse through activation of the SLC7A11/GPX4 pathway. Fer-1 may prevent AAA formation through activation of the SLC7A11/GPX4 pathway.

Calcineurin inhibition, cardiovascular consequences, vascular resistance, and potential responses.

To place the consequences of calcineurin inhibition in a cardiovascular context. Literature review coupled with personal encounters. Calcineurin is a calcium-binding and calmodulin-binding protein that is conserved across evolution from yeast to mammals. The enzyme functions as a calcium-dependent, calmodulin-stimulated protein phosphatase. Its role in regulating physiology has largely been elucidated by observing calcineurin inhibition. Calcineurin inhibition transformed organ transplantation from an experiment into a therapy and made much of general immunotherapy possible. The function of this phosphatase and how its inhibition leads to toxicity concern us to this date. Initial research from patients and animal models implicated a panoply of factors contributing to hypertension and vasculopathy. Subsequently, the role of calcineurin in regulating the effective fluid volume, sodium reabsorption, and potassium and hydrogen ion excretion was elucidated by investigating calcineurin inhibition. Understanding the regulatory effects of calcineurin on endothelial and vascular smooth muscle cell function has also made substantial progress. However, precisely how the increase in systemic vascular resistance arises requires further mechanistic research. Calcineurin inhibition continues to save lives; however, options to counteract the negative effects of calcineurin inhibition should be vigorously pursued.

HRD1 reduction promotes cholesterol-induced vascular smooth muscle cell phenotypic change via endoplasmic reticulum stress.

Phenotypic change of vascular smooth muscle cells (VSMCs) is the main contributor of vascular pathological remodeling in atherosclerosis. The endoplasmic reticulum (ER) is critical for maintaining VSMC function through elimination of misfolded proteins that impair VSMC cellular function. ER-associated degradation (ERAD) is an ER-mediated process that controls protein quality by clearing misfolded proteins. One of the critical regulators of ERAD is HRD1, which also plays a vital role in lipid metabolism. However, the function of HRD1 in VSMCs of atherosclerotic vessels remains poorly understood. The level of HRD1 expression was analyzed in aortic tissues of mice fed with a high-fat diet (HFD). The H&E and EVG (VERHOEFF'S VAN GIESON) staining were used to demonstrate pathological vascular changes. IF (immunofluorescence) and WB (western blot) were used to explore the signaling pathways in vivo and in vitro. The wound closure and transwell assays were also used to test the migration rate of VSMCs. CRISPR gene editing and transcriptomic analysis were applied in vitro to explore the cellular mechanism. Our data showed significant reduction of HRD1 in aortic tissues of mice under HFD feeding. VSMC phenotypic change and HRD1 downregulation were detected by cholesterol supplement. Transcriptomic and further analysis of HRD1-KO VSMCs showed that HRD1 deficiency induced the expression of genes related to ER stress response, proliferation and migration, but reduced the contractile-related genes in VSMCs. HRD1 deficiency also exacerbated the proliferation, migration and ROS production of VSMCs induced by cholesterol, which promoted the VSMC dedifferentiation. Our results showed that HRD1 played an essential role in the contractile homeostasis of VSMCs by negatively regulating ER stress response. Thus, HRD1 in VSMCs could serve as a potential therapeutic target in metabolic disorder-induced vascular remodeling.

Pharmacological inhibition of MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1) induces ferroptosis in vascular smooth muscle cells

MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1) is a human paracaspase protein with proteolytic activity via its caspase-like domain. The pharmacological inhibition of MALT1 by MI-2, a specific chemical inhibitor, diminishes the response of endothelial cells to inflammatory stimuli. However, it is largely unknown how MALT1 regulates the functions of vascular smooth muscle cells (SMCs). This study aims to investigate the impact of MALT1 inhibition by MI-2 on the functions of vascular SMCs, both in vitro and in vivo. MI-2 treatment led to concentration- and time-dependent cell death of cultured aortic SMCs, which was rescued by the iron chelator deferoxamine (DFO) or ferrostatin-1 (Fer-1), a specific inhibitor of ferroptosis, but not by inhibitors of apoptosis (Z-VAD-fmk), pyroptosis (Z-YVAD-fmk), or necrosis (Necrostatin-1, Nec-1). MI-2 treatment downregulated the expression of glutathione peroxidase 4 (GPX4) and ferritin heavy polypeptide 1 (FTH1), which was prevented by pre-treatment with DFO or Fer-1. MI-2 treatment also activated autophagy, which was inhibited by Atg7 deficiency or bafilomycin A1 preventing MI-2-induced ferroptosis. MI-2 treatment reduced the cleavage of cylindromatosis (CYLD), a specific substrate of MALT1. Notably, MI-2 treatment led to a rapid loss of contractility in mouse aortas, which was prevented by co-incubation with Fer-1. Moreover, local application of MI-2 significantly reduced carotid neointima lesions and atherosclerosis in C57BL/6J mice and apolipoprotein-E knockout (ApoE−/−) mice, respectively, which were both ameliorated by co-treatment with Fer-1. In conclusion, the present study demonstrated that MALT1 inhibition induces ferroptosis of vascular SMCs, likely contributing to its amelioration of proliferative vascular diseases.

Vascular dysfunction caused by loss of Brn-3b/POU4F2 transcription factor in aortic vascular smooth muscle cells is linked to deregulation of calcium signalling pathways

Phenotypic and functional changes in vascular smooth muscle cells (VSMCs) contribute significantly to cardiovascular diseases (CVD) but factors driving early adverse vascular changes are poorly understood. We report on novel and important roles for the Brn-3b/POU4F2 (Brn-3b) transcription factor (TF) in controlling VSMC integrity and function. Brn-3b protein is expressed in mouse aorta with localisation to VSMCs. Male Brn-3b knock-out (KO) aortas displayed extensive remodelling with increased extracellular matrix (ECM) deposition, elastin fibre disruption and small but consistent narrowing/coarctation in the descending aortas. RNA sequencing analysis showed that these effects were linked to deregulation of genes required for calcium (Ca2+) signalling, vascular contractility, sarco-endoplasmic reticulum (S/ER) stress responses and immune function in Brn-3b KO aortas and validation studies confirmed changes in Ca2+ signalling genes linked to increased intracellular Ca2+ and S/ER Ca2+ depletion [e.g. increased, Cacna1d Ca2+ channels; ryanodine receptor 2, (RyR2) and phospholamban (PLN) but reduced ATP2a1, encoding SERCA1 pump] and chaperone proteins, Hspb1, HspA8, DnaJa1 linked to increased S/ER stress, which also contributes to contractile dysfunction. Accordingly, vascular rings from Brn-3b KO aortas displayed attenuated contractility in response to KCl or phenylephrine (PE) while Brn-3b KO-derived VSMC displayed abnormal Ca2+ signalling following ATP stimulation. This data suggests that Brn-3b target genes are necessary to maintain vascular integrity /contractile function and deregulation upon loss of Brn-3b will contribute to contractile dysfunction linked to CVD.

Abstract 13229: Coiled-Coil Domain-Containing Protein 80 Protects Against Aortic Dissection by Maintaining the Contractile Smooth Muscle Cell Phenotype

Background: Aortic dissection (AD) is a life-threatening medical emergency characterized by adverse vascular remodeling. Effective prevention and treatment options are lacking for AD. Coiled-coil domain-containing protein 80 (CCDC80) plays an essential role in regulating vascular remodeling. In the present study, we aimed to define the role of CCDC80 in the formation and development of AD. Methods: The expression and subcellular localization of CCDC80 were determined in human and mouse AD. CCDC80 knockout mice (CCDC80 –/– ) and vascular smooth muscle cell (VSMC)-specific CCDC80 knockout mice (CCDC80 fl/fl SM22α Cre + ) were treated with angiotensin II (Ang II) or Ang II combined with β-aminopropionitrile monofumarate (BAPN) to induce AD models. RNA-Seq analysis combined with immunoprecipitation and blockage of the JAK2/STAT3 signaling pathway in CCDC80 –/– mice were used to evaluate the effect of CCDC80 deficiency on this pathway. Results: CCDC80 was downregulated in VSMCs in human and mouse AD. CCDC80 – / – mice challenged with Ang II and BAPN developed AD with higher frequency and severity compared with their littermate controls (66.7% vs. 100%, p < 0.05). Remarkably, compared with littermate controls treated with Ang II, CCDC80 –/– mice (8.3% vs. 87.5%, p < 0.05) and CCDC80 fl/fl SM22α Cre + mice (12.5% vs. 80%, p < 0.05) frequently developed AD with severe elastin fragmentation and collagen deposition. CCDC80 interacted with JAK2; CCDC80 deficiency could promote VSMC phenotype switching, proliferation, and migration as well as matrix metalloproteinase production by activating the JAK2/STAT3 signaling pathway. The JAK2/STAT3 pathway-specific inhibitor ameliorated adverse vascular remodeling and reduced AD formation (90% vs. 55%, p < 0.05) in CCDC80 knockout mice. Conclusion: CCDC80 deficiency exacerbates the progression of AD by activating the JAK2/STAT3 pathway involved in regulating the phenotype switching and function of VSMCs. Our findings suggest that CCDC80 is a potential target for the prevention and treatment of AD.

Resveratrol Inhibits Abdominal Aortic Aneurysm Progression by Reducing Extracellular Matrix Degradation, Apoptosis, Autophagy, and Inflammation of Vascular Smooth Muscle Cells via Upregulation of HMOX1.

This study aimed to explore the therapeutic effect of resveratrol (RES) against abdominal aortic aneurysm (AAA) and the role of HMOX1 underlying this effect. Vascular smooth muscle cells (VSMCs) were induced by angiotensin II (Ang II) to construct the microenvironment of AAA. HMOX1 expression was downregulated by the short hairpin ribonucleic acid (RNA) specific to HMOX1 in RES-pretreated VSMCs. The levels of matrix metalloproteinase (MMP)-2, MMP-9, and elastin were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot. Apoptosis rate was detected. The levels of apoptosis-related proteins (caspase-3 and Bax/Bcl-2), inflammatory cytokines (interleukin [IL]-6, tumor necrosis factor [TNF]-α, and IL-1β), and autophagy-related proteins (Beclin 1, light chain 3 [LC3] II/I, and p62) were detected by western blot. The secretion of inflammatory factors in cell supernatant was detected by enzyme-linked immunosorbent assay (ELISA). The number of autophagic vesicles in VSMCs was observed and analyzed by transmission electron microscopy. A rat model of pancreatic elastase-induced AAA was established to verify the effect and action mechanism of RES. Stimulation of Ang II increased the messenger RNA (mRNA) and protein levels of MMP-2 and MMP-9, decreased elastin expression, and enhanced apoptosis, secretion of inflammatory factors, and autophagy in VSMCs, whereas RES pretreatment ameliorated Ang II-induced VSMC dysfunction. In addition, HMOX1 mRNA and heme oxygenase-1 (HO-1) protein levels were significantly increased in VSMCs pretreated with RES compared with Ang II treatment alone. Silencing of HMOX1 abolished the effects of RES on VSMC dysfunction. Consistently, RES suppressed the development of AAA in rats by increasing the expression of HMOX1. Resveratrol protects against AAA by inhibiting extracellular matrix degradation, apoptosis, autophagy, and inflammation of VSMCs via HMOX1 upregulation. Our study found that angiotensin II (Ang II) stimulated increased the levels of MMP-2 and MMP-9 in vascular smooth muscle cells (VSMCs), decreased elastin expression, and promoted apoptosis, autophagy occurrence, and secretion of inflammatory factors, while resveratrol (RES) pretreatment improved this effect. In addition, downregulation of HMOX1 expression eliminated the effect of RES on the function of VSMCs. Our study elucidates that RES improves AAA progression through HMOX1 at both cellular and animal levels. This work can help doctors better understand the pathological mechanism of the occurrence and development of AAA, and provide a theoretical basis for clinicians to find better treatment options.

Activation of BMP4-pSmad1/5 pathway impairs the function of VSMCs in intracranial aneurysms

Intracranial aneurysms (IAs) are characterized by abnormal dilatation of the cerebral vessels. Vascular smooth muscle cells (VSMCs) are implicated in maintaining vascular homeostasis. Disordered VSMCs are one of the most common causes for occurrence and development of IAs. The bone morphogenetic protein 4 (BMP4) signalling pathway is involved in regulating cell proliferation, apoptosis, and differentiation. This study aimed to investigate the effects of BMP4 on VSMCs and its underlying mechanisms. BMP4 was upregulated in the VSMCs of IAs and caused apoptosis of VSMCs through Smad1/5 phosphorylation. In addition, BMP4 overexpression significantly promoted the proliferation and migration of VSMCs and induced a phenotypic transformation from contractile to inflammatory. Our findings facilitate further understanding of the occurrence and development of IAs and provide a potential therapeutic target.

PiRNA-823 is a novel potential therapeutic target in aortic dissection

Aortic dissection (AD) presents a medical challenge for clinicians. Here, to determine the role of a novel small non-coding piRNA-823 (piR-823) in AD, murine and human aorta from patients with AD were used. A high expression levels of piR-823 were found in patients with AD. Using performed loss- and gain-of-function assays in vitro and in vivo, we explore the regulatory effect of piR-823 on vascular smooth muscle cells (VSMCs) and AD. piR-823 obviously facilitates the proliferation, migration, and phenotypic transformation of VSMCs with or without nicotine treatment. piR-823 directly binds and suppresses histone deacetylase 1 (HDAC1) expression, and regulates the acetylation of histone 3 (H3) via H3K9ac and H3K27ac, eventually, VSMC functions and AD. To consolidate our findings, AD murine model was performed, and we observed that piR-823 antagomir strongly inhibited the pathogenesis of AD through regulating vascular remodeling. Thus, our study finds a potential target for the prevention and treatment strategy for nicotine-induced AD.

DDX24 Is Essential for Cell Cycle Regulation in Vascular Smooth Muscle Cells During Vascular Development via Binding to FANCA mRNA.

The DEAD-box family is essential for tumorigenesis and embryogenesis. Previously, we linked the malfunction of DDX (DEAD-box RNA helicase)-24 to a special type of vascular malformation. Here, we aim to investigate the function of DDX24 in vascular smooth muscle cells (VSMCs) and embryonic vascular development. Cardiomyocyte (CMC) and VSMC-specific Ddx24 knockout mice were generated by crossing Tagln-Cre mice with Ddx24flox/flox transgenic mice. The development of blood vessels was explored by stereomicroscope photography and immunofluorescence staining. Flow cytometry and cell proliferation assays were used to verify the regulation of DDX24 on the function of VSMCs. RNA sequencing and RNA immunoprecipitation coupled with quantitative real-time polymerase chain reaction were combined to investigate DDX24 downstream regulatory molecules. RNA pull-down and RNA stability experiments were performed to explore the regulation mechanism of DDX24. CMC/VSMC-specific Ddx24 knockout mice died before embryonic day 13.5 with defects in vessel formation and abnormal vascular remodeling in extraembryonic tissues. Ddx24 knockdown suppressed VSMC proliferation via cell cycle arrest, likely due to increased DNA damage. DDX24 protein bound to and stabilized the mRNA of FANCA (FA complementation group A) that responded to DNA damage. Consistent with the function of DDX24, depletion of FANCA also impacted cell cycle and DNA repair of VSMCs. Overexpression of FANCA was able to rescue the alterations caused by DDX24 deficiency. Our study unveiled a critical role of DDX24 in VSMC-mediated vascular development, highlighting a potential therapeutic target for VSMC-related pathological conditions.

Vascular smooth muscle cells in intracranial aneurysms

Intracranial aneurysm (IA) is a severe cerebrovascular disease characterized by abnormal bulging of cerebral vessels that may rupture and cause a stroke. The expansion of the aneurysm accompanies by the remodeling of vascular matrix. It is well-known that vascular remodeling is a process of synthesis and degradation of extracellular matrix (ECM), which is highly dependent on the phenotype of vascular smooth muscle cells (VSMCs). The phenotypic switching of VSMC is considered to be bidirectional, including the physiological contractile phenotype and alternative synthetic phenotype in response to injury. There is increasing evidence indicating that VSMCs have the ability to switch to various phenotypes, including pro-inflammatory, macrophagic, osteogenic, foamy and mesenchymal phenotypes. Although the mechanisms of VSMC phenotype switching are still being explored, it is becoming clear that phenotype switching of VSMCs plays an essential role in IA formation, progression, and rupture. This review summarized the various phenotypes and functions of VSMCs associated with IA pathology. The possible influencing factors and potential molecular mechanisms of the VSMC phenotype switching were further discussed. Understanding how phenotype switching of VSMC contributed to the pathogenesis of unruptured IAs can bring new preventative and therapeutic strategies for IA.

Hsa_circ_0031891 targets miR-579-3p to enhance HMGB1 expression and regulate PDGF-BB-induced human aortic vascular smooth muscle cell proliferation, migration, and dedifferentiation.

Atherosclerosis (AS) is an underlying cause of the majority of coronary artery disease (CAD), in which proliferation, migration, and dedifferentiation of vascular smooth muscle cells (VSMCs) exert vital roles. It has been reported that circular RNAs (circRNAs) are associated with the VSMCs function. Here, we undertook to explore the biological function and mechanism of hsa_circ_0031891 in a platelet-derived growth factor-BB (PDGF-BB)-induced AS cell model. Hsa_circ_0031891 and microRNA-579-3p (miR-579-3p) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation and migration were detected using Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), wound healing, and transwell assay. Protein levels of alpha-smooth muscle actin (α-SMA), smooth muscle protein 22-α (SM22-α), Osteopontin, and High mobility group box-1 (HMGB1) were determined using western blot assay. After predicting via a variety of bioinformatics software, the binding between miR-579-3p and hsa_circ_0031891 or HMGB1 was validated using dual-luciferase reporter and RNA pull-down assays. Increased hsa_circ_0031891 and HMGB1 and reduced miR-579-3p were found in CAD patients and PDGF-BB-induced human aortic vascular smooth muscle cells (HA-VSMCs). Moreover, hsa_circ_0031891 deficiency relieved PDGF-BB-mediated HA-VSMC proliferation, migration, and dedifferentiation. Mechanically, hsa_circ_0031891 modulated HMGB1 expression via sponging miR-579-3p. Hsa_circ_0031891 boosted PDGF-BB-induced proliferation, migration, and dedifferentiation partly by regulating the miR-579-3p/HMGB1 axis, hinting at a feasible therapeutic strategy for AS.

Atherogenic Activation of Human Vascular Smooth Muscle Cells by Monosodium Urate Crystals

Gout is strongly associated with atherosclerosis and other cardiovascular comorbidities. Furthermore, sites of extra-articular monosodium urate (MSU) crystal deposits in gout can include heart valves and atherosclerotic artery plaques, but with unclear effects therein. Hence, we seminally explored cultured vascular smooth muscle cell (VSMC) responsiveness to MSU crystals. To limit confounding effects, we cultured human aortic VSMCs under serum-free conditions to assess MSU crystal effects on VSMC differentiation and function, differentially expressed genes (DEGs) via RNA sequencing, and selected atherogenic changes in cytokines and the lipidome. MSU crystals induced p38 phosphorylation, IL-6, and VSMC vacuolization with dysregulated autophagy. MSU-crystal-induced DEGs included decreased late-stage autophagosome maturation mediator GABARAPL1, decreased physiologic VSMC differentiation regulators (LMOD1 and SYNPO2), increased ATF4, CHOP, and the intrinsic apoptosis signaling pathway in response to ER stress, and neointimal atherogenic nuclear receptors (NR4A1 and NR4A3). MSU crystals alone increased the levels of cholesterol biosynthetic intermediates 14-demethyl-lanosterol (14-DML), desmosterol, and zymosterol. Adding MSU crystals increased oxidized LDL’s capacity to increase intracellular 27-OH cholesterol, and MSU crystals and oxidized LDL synergistically induced a marked release of arachidonate. In conclusion, MSU crystals deposited in arterial media and neointima have the potential to dysregulate VSMC differentiation and proteostasis, and to induce further atherogenic effects, which include enhanced VSMC loading of oxidized cholesterol intermediates and release of IL-6 and arachidonic acid (AA).