SIRT1 improves VSMC functions in atherosclerosis

Targeting PDGF/PDGFR Signaling Pathway by microRNA, lncRNA, and circRNA for Therapy of Vascular Diseases: A Narrow Review

Despite the significant progress in diagnostic and therapeutic strategies, vascular diseases, such as cardiovascular diseases (CVDs) and respiratory diseases, still cannot be successfully eliminated. Vascular cells play a key role in maintaining vascular homeostasis. Notably, a variety of cells produce and secrete platelet-derived growth factors (PDGFs), which promote mitosis and induce the division, proliferation, and migration of vascular cells including vascular smooth muscle cells (SMCs), aortic SMCs, endothelial cells, and airway SMCs. Therefore, PDGF/PDGR receptor signaling pathways play vital roles in regulating the homeostasis of blood vessels and the onset and development of CVDs, such as atherosclerosis, and respiratory diseases including asthma and pulmonary arterial hypertension. Recently, accumulating evidence has demonstrated that microRNA, long-chain non-coding RNA, and circular RNA are involved in the regulation of PDGF/PDGFR signaling pathways through competitive interactions with target mRNAs, contributing to the occurrence and development of the above-mentioned diseases. These novel findings are useful for laboratory research and clinical studies. The aim of this article is to conclude the recent progresses in this field, particular the mechanisms of action of these non-coding RNAs in regulating vascular remodeling, providing potential strategies for the diagnosis, prevention, and treatment of vascular-dysfunction-related diseases, particularly CVDs and respiratory diseases.

(-)-Epicatechin gallate prevented atherosclerosis by reducing abnormal proliferation of VSMCs and oxidative stress of AML 12 cells

(-)-Epicatechin gallate (ECG) is beneficial to the treatment of cardiovascular diseases (CVDs), especially atherosclerosis (AS) through antioxidant stress, but there is a lack of detailed mechanism research. In this study, the therapeutic target of ECG was determined by crossing the drug target and disease target of CVDs and AS. The combination ability of ECG with important targets was verified by Discovery Studio software. The abnormal proliferation of vascular smooth muscle cells (VSMCs) induced by Ang-II and the oxidative damage of AML 12 induced by H2O2 were established to verify the reliability of ECG intervention on the target protein. A total of 120 ECG targets for the treatment of CVDs-AS were predicted by network pharmacology. The results of molecular docking showed that ECG has strong binding force with VEGFA, MMP-9, CASP3 and MMP-2 domains. In vitro experiments confirmed that ECG significantly reduced the expression of VEGFA, MMP-9, CASP3 and MMP-2 in Ang-II-induced VSMCs, and also blocked the abnormal proliferation, oxidative stress and inflammatory reaction of VSMCs by inhibiting the phosphorylation of PI3K signaling pathway. At the same time, ECG also interfered with H2O2-induced oxidative damage of AML 12 cells, decreased the expression of ROS and MDA and cell foaming, and increased the activities of antioxidant enzymes such as SOD, thus playing a protective role.

SIRT1-dependent PGC-1α deacetylation by SRT1720 rescues progression of atherosclerosis by enhancing mitochondrial function

Vascular smooth muscle cell (VSMC) senescence promotes atherosclerosis via lipid-mediated mitochondrial dysfunction and oxidative stress. However, the mechanisms of mitochondrial dysfunction and VSMC senescence in atherosclerosis have not been established. Here, we investigated the mechanisms whereby signaling pathways regulated by SRT1720 enhance or regulate mitochondrial functions in atherosclerotic VSMCs to suppress atherosclerosis. Initially, we examined the effect of SRT1720 on oleic acid (OA)-induced atherosclerosis. Atherosclerotic VSMCs exhibited elevated expressions of BODIPY and ADRP (adipose differentiation-related protein) and associated intracellular lipid droplet markers. In addition, the expression of collagen I was upregulated by OA, while the expressions of elastin and α-SMA were downregulated. mtDNA copy numbers, an ATP detection assay, transmission electron microscopy (TEM) imaging of mitochondria, mitochondria membrane potentials (assessed using JC-1 probe), and levels of mitochondrial oxidative phosphorylation (OXPHOS) were used to examine the effects of SRT1720 on OA-induced mitochondrial dysfunction. SRT1720 reduced mtDNA damage and accelerated mitochondria repair in VSMCs with OA-induced mitochondria dysfunction. In addition, mitochondrial reactive oxygen species (mtROS) levels were downregulated by SRT1720 in OA-treated VSMCs. Importantly, SRT1720 significantly increased SIRT1 and PGC-1α expression levels, but VSMCs senescence, inflammatory response, and atherosclerosis phenotypes were not recovered by treating cells with EX527 and SR-18292 before SRT1720. Mechanistically, the upregulations of SIRT1 and PGC-1α deacetylation by SRT1720 restored mitochondrial function, and consequently suppressed VSMC senescence and atherosclerosis-associated proteins and phenotypes. Collectively, this study indicates that SRT1720 can attenuate OA-induced atherosclerosis associated with VSMC senescence and mitochondrial dysfunction via SIRT1-mediated deacetylation of the PGC-1α pathway.

Sirtuins in macrophage immune metabolism: A novel target for cardiovascular disorders

Sirtuins (SIRT1-SIRT7), as a family of NAD+-dependent protein modifying enzymes, have various catalytic functions, such as deacetylases, dealkalylases, and deribonucleases. The Sirtuins family is directly or indirectly involved in pathophysiological processes such as glucolipid metabolism, oxidative stress, DNA repair and inflammatory response through various pathways and assumes an important role in several cardiovascular diseases such as atherosclerosis, myocardial infarction, hypertension and heart failure. A growing number of studies supports that metabolic and bioenergetic reprogramming directs the sequential process of inflammation. Failure of homeostatic restoration leads to many inflammatory diseases, and that macrophages are the central cells involving the inflammatory response and are the main source of inflammatory cytokines. Regulation of cellular metabolism has emerged as a fundamental process controlling macrophage function, but its exact signaling mechanisms remain to be revealed. Understanding the precise molecular basis of metabolic control of macrophage inflammatory processes may provide new approaches for targeting immune metabolism and inflammation. Here, we provide an update of studies in cardiovascular disease on the function and role of sirtuins in macrophage inflammation and metabolism, as well as drug candidates that may interfere with sirtuins, pointing to future prospects in this field.

Elevated circulating inflammatory biomarker levels in the SIRT1-NF-κB-sCD40L pathway in patients with acute myocardial infarction: a case-control study

BACKGROUND

Inflammation plays a key role in atherosclerosis development and progression. However, the role of novel inflammatory biomarker pathways, namely the SIRT1-NF-κB-sCD40L, in the etiopathogenesis of human atherosclerosis remains undefined. This study was designed to evaluate the changes and clinical implications of these inflammatory mediators in the plasma of patients with acute myocardial infarction (AMI).

METHODS

The peripheral arterial blood of 88 participants (68 patients with AMI and 20 age-matched controls), was drawn prior to performing coronary angiography (CAG). The SIRT1, NF-κB, and sCD40L plasma levels were quantified using ELISA. Spearman's analysis was used to evaluate the correlation between the three inflammatory markers, while Pearson's test assessed their potential correlation with cardiac troponin T (TNT) levels. Sensitivity, specificity, and area under the ROC curve (AUC) were calculated as measures of diagnostic accuracy.

RESULTS

Patients with AMI showed higher levels of circulating SIRT1, NF-κB, and sCD40L compared to the age-matched controls (p < 0.05). However, the plasma concentrations of these three inflammatory mediators did not differ between the ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) patients. Additionally, in patients with AMI, the SIRT1 level was positively correlated with NF-κB and sCD40L levels (p < 0.001). Likewise, the levels of SIRT1, NF-κB and sCD40L were positively correlated with TNT levels (p < 0.001). More importantly, the ROC analysis showed that the diagnostic accuracy of AMI was significantly higher when NF-κB or sCD40L level was used in combination with TNT levels (p < 0.05).

CONCLUSIONS

The levels of the circulating inflammatory biomarkers, including SIRT1, NF-κB, and sCD40L, were significantly elevated in patients with AMI. These novel biomarkers can improve the diagnostic accuracy of AMI when combined with TNT.KEY MESSAGESAMI is a potentially lethal CAD and is the leading cause of mortality and morbidity worldwide. Inflammation plays a key role in atherosclerosis development and progression. The levels of the circulating novel inflammatory biomarkers, including SIRT1, NF-κB, and sCD40L, were significantly elevated in patients with AMI.The SIRT1 level was positively correlated with NF-κB and sCD40L levels in patients with AMI.The levels of SIRT1, NF-κB and sCD40L were positively correlated with TNT levels.The ROC analysis showed that the diagnostic accuracy of AMI was significantly higher when NF-κB or sCD40L level was used in combination with TNT levels.SIRT1/NF-κB/sCD40L axis inhibition is a potential new target for AMI treatment.

Platelet factor 4 (PF4) induces cluster of differentiation 40 (CD40) expression in human aortic endothelial cells (HAECs) through the SIRT1/NF-κB/p65 signaling pathway

PF4 is a pro-atherosclerotic molecule. Endothelial CD40, upon binding to its ligand CD40L, induces endothelial cell (EC) activation, which is a vital pathophysiological process in the initiation and progression of atherosclerosis. However, the relationship between PF4 and endothelial CD40 remains elusive. This study aims to investigate whether and how PF4 affects endothelial CD40 expression using primary HAECs. PF4 treatment down-regulated sirtuin 1 (SIRT1) expression but upregulated the expression of acetylated NF-κB p65 (Ac-p65) and CD40 in HAECs in a concentration- and time-dependent manner. Pretreatment with SIRT1 agonist (SRT1720 or RSV) or SIRT1-overexpressing lentivirus attenuated PF4-induced Ac-p65 and CD40 expression in HAECs, whereas preincubation with SIRT1 antagonist (NAM or EX527) or SIRT1 shRNA had the opposite effect. To investigate whether NF-κB/p65 signaling pathway modulates CD40 expression in PF4-treated HAECs, PDTC, a NF-κB inhibitor, and p65-shRNA were introduced. PDTC or p65-shRNA treatment down-regulated Ac-p65 expression in HAECs. PDTC or p65-shRNA preincubation suppressed CD40 expression in HAECs after PF4 treatment. To better determine whether SIRT1 regulates CD40 expression in PF4-treated HAECs via the NF-κB/p65 signaling pathway, p65-knockdown HAECs were preincubated with SIRT1 agonists before PF4 treatment. SIRT1 agonist preincubation further decreased CD40 expression in p65-knockdown HAECs treated with PF4. Moreover, PF4 treatment promoted p65 nuclear translocation in HAECs. The results of dual luciferase assay demonstrated that four NF-κB binding sites in the promoter of human CD40 gene were activated in PF4-treated HAECs. In conclusion, our findings suggest that PF4 treatment facilitates CD40 expression in HAECs through the SIRT1/NF-κB/p65 pathway.

Regulation of Acetylation States by Nutrients in the Inhibition of Vascular Inflammation and Atherosclerosis

Atherosclerosis (AS) is a chronic metabolic disorder and primary cause of cardiovascular diseases, resulting in substantial morbidity and mortality worldwide. Initiated by endothelial cell stimulation, AS is characterized by arterial inflammation, lipid deposition, foam cell formation, and plaque development. Nutrients such as carotenoids, polyphenols, and vitamins can prevent the atherosclerotic process by modulating inflammation and metabolic disorders through the regulation of gene acetylation states mediated with histone deacetylases (HDACs). Nutrients can regulate AS-related epigenetic states via sirtuins (SIRTs) activation, specifically SIRT1 and SIRT3. Nutrient-driven alterations in the redox state and gene modulation in AS progression are linked to their protein deacetylating, anti-inflammatory, and antioxidant properties. Nutrients can also inhibit advanced oxidation protein product formation, reducing arterial intima-media thickness epigenetically. Nonetheless, knowledge gaps remain when it comes to understanding effective AS prevention through epigenetic regulation by nutrients. This work reviews and confirms the underlying mechanisms by which nutrients prevent arterial inflammation and AS, focusing on the epigenetic pathways that modify histones and non-histone proteins by regulating redox and acetylation states through HDACs such as SIRTs. These findings may serve as a foundation for developing potential therapeutic agents to prevent AS and cardiovascular diseases by employing nutrients based on epigenetic regulation.

ox-LDL regulates proliferation and apoptosis in VSMCs by controlling the miR-183-5p/FOXO1

BACKGROUND

microRNA-mRNA axes that are involved in oxidized low-density lipoprotein (ox-LDL)-induced vascular smooth muscle cells (VSMCs) proliferation/apoptosis imbalance need to be further investigated.

OBJECTIVE

To investigate the functional role of miR-183-5p/FOXO1 in VSMCs and its interaction with ox-LDL.

METHODS

RNA sequencing was used to detect transcriptome changes of VSMCs treated with ox-LDL. miR-183-5p and FOXO1 expression levels in VSMCs after ox-LDL treatment were assessed using qRT-PCR and western blotting. The regulatory effect of miR-183-5p on FOXO1 has been tried to prove using a dual-luciferase reporter assay. The functions of miR-183-5p, and FOXO1 were analyzed by CCK-8 assay and flow cytometry assay. The tissue samples or serum samples of high fat-feeding mice and carotid atherosclerosis patients were collected, and the levels of miR-183-5p/FOXO1 were analyzed.

RESULTS

RNA sequencing data showed 81 miRNAs including miR-183-5p was significantly changed after ox-LDL treatment in VSMCs. FOXO1, a miR-183-5p's potential target, was also down-regulated in ox-LDL treated cells. qRT-PCR and western blot found that expression of FOXO1 mRNA and protein significantly reduced in VSMCs treated with ox-LDL, accompanied by overexpression of miR-183-5p. miR-183-5p inhibited FOXO1 mRNA by binding to its 3' UTR. Interference miR-183-5p/FOXO1 could change proliferation/apoptosis imbalance in VSMCs under ox-LDL stimulation. Higher levels of miR-183-5p but reduced FOXO1 can be found in the thoracic aorta tissues of high fat-feeding mice. In serum samples from individuals with carotid atherosclerosis, Higher levels of miR-183-5p were observed. the miR-183-5p level was positively related to the level of serum ox-LDL in patients.

CONCLUSIONS

Aberrant expression of miR-183-5p/FOXO1 pathway mediated ox-LDL-induced proliferation/apoptosis imbalance in VSMCs. The miR-183-5p/FOXO1 axis can potentially be utilized as the target in the treatment of patients with atherosclerosis.

The Molecular Pathways of Pyroptosis in Atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease seriously endangering human health, whose occurrence and development is related to many factors. Pyroptosis is a recently identified novel programmed cell death associated with an inflammatory response and involved in the formation and progression of AS by activating different signaling pathways. Protein modifications of the sirtuin family and microRNAs (miRNAs) can directly or indirectly affect pyroptosis-related molecules. It is important to link atherosclerosis, thermogenesis and molecular modifications. This article will systematically review the molecular pathways of pyroptosis in AS, which can provide a new perspective for AS prevention and treatment.

Angiotensin II upregulates endothelin receptors through the adenosine monophosphate-activated protein kinase/sirtuin 1 pathway in vascular smooth muscle cells

OBJECTIVES

This study was designed to test our hypothesis that angiotensin II (Ang II) upregulates endothelin (ET) receptors in vascular smooth muscle cells (VSMCs).

METHODS

Rat superior mesenteric artery (SMA) without endothelium was cultured in serum-free medium for 24 h in the presence of Ang II with or without metformin or nicotinamide. In vivo, rats were implanted subcutaneously with a mini-osmotic pump infusing AngII (500 ng/kg/min) for 4 weeks. The level of protein expression was determined using Western blotting. The contractile response to ET receptor agonists was studied using sensitive myography. Caudal artery blood pressure (BP) was measured using non-invasive tail-cuff plethysmography.

KEY FINDINGS

The results showed that Ang II significantly increased ET receptors and decreased phosphorylated-adenosine monophosphate-activated protein kinase α (p-AMPKα) in SMA. Furthermore, metformin significantly inhibited Ang II-upregulated ET receptors and upregulated Ang II-decreased sirtuin 1 (Sirt1). However, this effect was reversed by nicotinamide. Moreover, the in-vivo results showed that metformin not only inhibited Ang II-induced upregulation of ET receptors but also recovered Ang II-decreased p-AMPKα and Sirt1. In addition, metformin significantly inhibited Ang II-elevated BP. However, the effect was reversed by nicotinamide, except for p-AMPKα.

CONCLUSIONS

Ang II upregulated ET receptors in VSMCs to elevate BP by inhibiting AMPK, thereby inhibiting Sirt1.

Cullin3 (CUL3) suppresses proliferation, migration and phenotypic transformation of PDGF-BB-stimulated vascular smooth muscle cells and mitigates inflammatory response by repressing Hedgehog signaling pathway

Vascular smooth muscle cell (VSMC) hyperplasia is closely associated with AS progression. Hence, it is of great significance to elucidate the molecular mechanisms underlying the involvement of VSMCs in AS. SHH antagonist can inhibit the excessive proliferation, migration and phenotypic transformation of PDGF-BB-induced VSMCs. It has been proved that CUL3 can suppress Hedgehog signaling. This current work was designed to identify the biological role of CUL3 in the behaviors of VSMCs in AS and investigate the potential molecular mechanism. VSMCs were treated with PDGF-BB to establish the cell model in vitro. Levels of CUL3, SHH and Gli1 in PDGF-BB-stimulated VSMCs were measured by RT-qPCR analysis. Then, the precise functions of CUL3 in VSMCs were determined from the perspectives of proliferation, migration, apoptosis and phenotype transformation. Besides, the influence of CUL3 on inflammatory response in VSMCs was evaluated. Moreover, the impact of CUL3 on Hedgehog signaling pathway was also investigated. In the present research, it was observed that CUL3 was lowly expressed and SHH and Gli1 were highly expressed in PDGF-BB-stimulated VSMCs. Upregulation of CUL3 suppressed the excessive proliferation, migration and phenotypic transformation and facilitated the apoptosis of PDGF-BB-stimulated VSMCs. In addition, elevation of CUL3 alleviated inflammatory response in PDGF-BB-stimulated VSMCs. Importantly, CUL3 overexpression inactivated Hedgehog signaling pathway. To conclude, CUL3 might regulate the biological behaviors of VSMCs in AS by modulating Hedgehog signaling pathway. These data encourage to further investigate any potential therapeutic role of CUL3 in animal models of AS and explore therapeutic values for AS clinically.

CircMAPK1 promotes the proliferation and migration of vascular smooth muscle cells through miR-22-3p/ methyl-CpG binding protein 2 axis

BACKGROUND AND AIMS

Atherosclerosis is a chronic inflammatory disease. The proliferation and migration of vascular smooth muscle cells (VSMCs) contribute to intimal hyperplasia. CircRNAs are class of endogenous RNA and implicated in the various biological processes. However, the role of circRNAs in atherosclerosis remains largely unknown.

METHODS AND RESULTS

Mice models of atherosclerosis were established using APOE-/- mice fed with high-fat diet. High-throughput sequencing was performed to profile the expression of circRNAs in atherosclerosis. A total of 1289 circRNAs were identified. Six circRNAs were up-regulated and 12 circRNAs were down-regulated in the atherosclerotic plaque tissues. Then we focused on circMAPK1, which showed a high level in atherosclerosis. Silencing circMAPK1 suppressed the proliferation and migration of VSMCs. Further study showed that circMAPK1 bound with miR-22-3p. CircMAPK1 silencing increased the level of miR-22-3p and suppressed the level of MECP2, a known target of miR-22-3p. Interestingly, suppression of miR-22-3p rescued the effect of circMAPK1 silencing on the proliferation and migration of VSMCs.

CONCLUSION

CircMPAK1 promoted the proliferation and migration of VSMCs through miR-22-3p/MECP2 axis. Our study revealed the role of circMAPK1 in atherosclerosis and shed lights on the treatment of atherosclerosis.

The role of TRPV1 channels in atherosclerosis

Transient receptor potential vanilloid subfamily member 1 (TRPV1) is a nonselective cation channel, that is mainly distributed in sensory nerve endings and can release a variety of neurotransmitters after activation. Early studies showed that it mainly conducts pain sensation, but research has demonstrated that it also plays an important role in cardiovascular diseases. Notably, in atherosclerosis, the activation of TRPV1 can regulate lipid metabolism, reduce foam cell formation, protect endothelial cells, inhibit smooth muscle cell proliferation and inhibit inflammation and oxidation. In this review, the role of the TRPV1 channel in atherosclerosis was discussed to provide new ideas for the prevention and treatment of atherosclerotic diseases.

miR-34c inhibits PDGF-BB-induced HAVSMCs phenotypic transformation and proliferation via PDGFR-β/SIRT1 pathway

The purpose of this study was to explore the effect of miR-34c on PDGF-BB-induced HAVSMCs phenotypic transformation and proliferation via PDGFR-β/SIRT1 pathway, so as to find a new method for early diagnosis and treatment of cardiovascular disease. HA-VSMCs were treated with platelet-derived growth factor-BB (PDGF-BB) at 0 h, 12 h, 24 h, 48 h or 36 h to explore the optimal time for phenotypic transformation of VSMCs. And then, PDGF-BB-induced HA-VSMCs were transfected with miR-34c mimics/mimics NC and pcDNA3.1-PDGFR-β/pcDNA3.1-NC to observe cell biological behaviour. CCK8 was used to detect cell proliferation activity. Transwell chamber assay was used to detect cell invasion. Early apoptosis was analyzed by flow cytometry. The expression of α-SMA and Smemb was detected by immunofluorescence staining. The expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1 were analyzed by Western blot analysis. The expression of miR-34a, miR-34b and miR-34c was detected by RT-PCR, and the targeting relationship between miR-34c and PDGFR-β was detected by luciferase reporting assay. The results indicated the proliferation and migration of PDGF-BB-induced HA-VSMCs significantly increased, and apoptosis significantly decreased. Besides, α-SMA decreased significantly, while Smemb increased significantly. Furthermore, expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1 increased significantly, and SIRT1 decreased significantly. Experimental results showed that, miR-34c mimics significantly inhibited cell proliferation and migration, and promoted cell apoptosis, and miR-34c inhibitor had the opposite effects. MiR-34c mimics significantly increased α-SMA expression and decreased Smemb expression, while the opposite effects were reflected after transfection with miR-34c inhibitor. Moreover, miR-34c mimics significantly decreased the expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1, and significantly increased the expression of SIRT1, while miR-34c inhibitor had the opposite effects. Luciferase assay confirmed that PDGFR-β was a potential target of miR-34c. Subsequently, PDGF-BB-induced HA-VSMCs were co-transfected with miR-34c mimics and pcDNA3.1-PDGFR-β. The results indicated that PDGFR-β reversed the biological function of miR-34c mimic. The results revealed the potential application value of miR-34c as a marker molecule of phenotypic transformation, providing a potential target for improving phenotypic transformation.

Phylogenic Determinants of Cardiovascular Frailty, Focus on Hemodynamics and Arterial Smooth Muscle Cells

The evolution of the circulatory system from invertebrates to mammals has involved the passage from an open system to a closed in-parallel system via a closed in-series system, accompanying the increasing complexity and efficiency of life’s biological functions. The archaic heart enables pulsatile motion waves of hemolymph in invertebrates, and the in-series circulation in fish occurs with only an endothelium, whereas mural smooth muscle cells appear later. The present review focuses on evolution of the circulatory system. In particular, we address how and why this evolution took place from a closed, flowing, longitudinal conductance at low pressure to a flowing, highly pressurized and bifurcating arterial compartment. However, although arterial pressure was the latest acquired hemodynamic variable, the general teleonomy of the evolution of species is the differentiation of individual organ function, supported by specific fueling allowing and favoring partial metabolic autonomy. This was achieved via the establishment of an active contractile tone in resistance arteries, which permitted the regulation of blood supply to specific organ activities via its localized function-dependent inhibition (active vasodilation). The global resistance to viscous blood flow is the peripheral increase in frictional forces caused by the tonic change in arterial and arteriolar radius, which backscatter as systemic arterial blood pressure. Consequently, the arterial pressure gradient from circulating blood to the adventitial interstitium generates the unidirectional outward radial advective conductance of plasma solutes across the wall of conductance arteries. This hemodynamic evolution was accompanied by important changes in arterial wall structure, supported by smooth muscle cell functional plasticity, including contractility, matrix synthesis and proliferation, endocytosis and phagocytosis, etc. These adaptive phenotypic shifts are due to epigenetic regulation, mainly related to mechanotransduction. These paradigms actively participate in cardio-arterial pathologies such as atheroma, valve disease, heart failure, aneurysms, hypertension, and physiological aging.

Silencing CCL8 inhibited the proliferation and migration of PDGF-BB-stimulated human aortic smooth muscle cells

C-C motif Chemokine ligand 8 (CCL8) has been found in diseases' pathogenesis. But its molecular mechanism in atherosclerosis (AS) remains to be elucidated. Human aortic smooth muscle cells (HASMCs) were stimulated by PDGF-BB to establish cell model. α-SMA in PDGF-BB-stimulated HASMCs was measured by immunofluorescence staining. Relative gene expressions in PDGF-BB-stimulated HASMCs were detected by quantitative real-time polymerase chain reaction and western blot. HASMCs proliferation, migration, and cell cycle were assessed by cell counting kit-8, wound-healing assay, and flow cytometry. HASMCs viability was increased after PDGF-BB stimulation, with α-SMA downregulation yet CCL8 upregulation. Silencing CCL8 inhibited PDGF-BB-stimulated HASMCs proliferation and migration, and increased cells percentage in G1 phases but decreased those in S phase. Also, silencing CCL8 decreased OPN and cyclinD1 expressions and AKT and ERK1/2 phosphorylation while increased those of α-SMA and Sm22α. However, upregulating CCL8 led to opposite effects, suggesting CCL8 could be an atherosclerosis therapeutic target.

Membrane cholesterol and substrate stiffness co-ordinate to induce the remodelling of the cytoskeleton and the alteration in the biomechanics of vascular smooth muscle cells

AIMS

Cholesterol not only deposits in foam cells at the atherosclerotic plaque, but also plays an important role as a regulator of cell migration in atherogenesis. In addition, the progression of atherosclerosis leads to arterial wall stiffening, and thus altering the micromechanical environment of vascular smooth muscle cells (VSMCs) in vivo. Our studies aim to test the hypothesis that membrane cholesterol and substrate stiffness co-ordinate to regulate VSMCs biomechanics, and thus potentially regulate VSMCs migration and atherosclerotic plaque formation.

METHODS AND RESULTS

Methyl-β-cyclodextrin was used to manipulate membrane cholesterol content in VSMCs isolated from the descending thoracic aorta of male Sprague-Dawley rats and cultured on Type I collagen-coated polyacrylamide gel substrates with varying stiffness. Atomic force microscopy (AFM) was used to determine VSMCs stiffness and integrin-fibronectin (FN) adhesion. The alignment of submembranous actin filaments was visualized with AFM and confocal microscopy. The constriction force of rat aorta was measured ex vivo using a multi-wire myograph system. Our results demonstrated that cholesterol-depletion and substrate-softening induced a significant decrease in VSMCs stiffness and adhesion to FN, as well as cytoskeletal disorganization. In addition, the contractile force of rat aorta was reduced upon cholesterol-depletion. Cholesterol-enrichment resulted in an increase in stiffness, adhesion to FN, cytoskeletal organization of VSMCs compared with the cholesterol-depleted cells, and enhanced contractile force of rat aortas compared with the cholesterol-depleted vessel rings.

CONCLUSION

Cell membrane cholesterol and substrate stiffness synergistically affect VSMCs elastic modulus (E-modulus) by regulating the organization of the actin cytoskeleton. Except for the 3.5 kPa gel substrate, cholesterol-depletion decreased VSMCs-FN adhesion force, adhesion loading rate, cytoskeletal orientation, and E-modulus compared with the control VSMCs. Conversely, cholesterol-enrichment significantly increased cytoskeleton orientation, stiffness, and VSMCs-FN cell adhesion force compared with both control and cholesterol-depleted VSMCs on a soft substrate.

Luteolin decreases atherosclerosis in LDL receptor-deficient mice via a mechanism including decreasing AMPK-SIRT1 signaling in macrophages

Lipid metabolism dysfunction and inflammatory infiltration into arterial walls are associated with the initiation and progression of atherosclerosis. Luteolin has been reported to possess anti-inflammatory actions and protect against tumor necrosis factor-α (TNF-α)-induced vascular inflammation, monocyte adhesion to endothelial cells and the formation of lipid-laden macrophages in vitro. However, the role of luteolin in atherosclerosis and the associated vascular inflammatory remains to be elucidated. The aim of the present study was to investigate the effects of luteolin on plaque development, lipid accumulation and macrophage inflammation low-density lipoprotein receptor-deficient (LDLR^-/-) mice with atherosclerosis, as well as the underlying mechanisms in ox-induced THP-1-derived macrophages. Firstly, 9-week-old male C57BL/6 mice were fed a standard chow diet, western diet or western diet supplemented with 100 mg/kg luteolin for 14 weeks. The results of histological staining revealed that 100 mg/kg dietary luteolin ameliorated western diet-induced atherosclerotic plaque development and lipid accumulation in the abdominal aorta. Furthermore, total cholesterol, triglyceride and LDL-cholesterol levels were decreased in the plasma of western diet + luteolin mice compared with those fed with a western diet alone. Quantitative polymerase chain reaction analysis revealed that dietary luteolin inhibited the expression of cluster of differentiation 68, macrophage chemoattractant protein 2 and inflammatory cytokines, including interleukin-6 (IL-6) and TNF-α. Mechanistically, luteolin decreased the total cholesterol level as well as macrophage chemokine and inflammatory cytokine expression in THP-1-derived macrophages via AMP-activated protein kinase (AMPK)-Sirtuin (SIRT)1 signaling following induction with oxidized low-density lipoprotein. The results of the present study suggest that luteolin prevents plaque development and lipid accumulation in the abdominal aorta by decreasing macrophage inflammation during atherosclerosis, which is mediated by mechanisms including AMPK-SIRT1 signaling.

SHP2 inhibitor PHPS1 protects against atherosclerosis by inhibiting smooth muscle cell proliferation

BACKGROUND

Smooth muscle cells play an important role in the development of atherosclerosis. SHP2 is known to regulate the proliferation and migration of smooth muscle cells. The purpose of this study was to determine whether the SHP2 inhibitor PHPS1 has a pro-atherosclerotic or an atheroprotective effect in vivo and in vitro.

METHODS

After exposure to a high-cholesterol diet for 4 weeks, LDL receptor-deficient (Ldlr-/-) mice were exposed to the SHP2 inhibitor PHPS1 or vehicle. Body weight, serum glucose and lipid levels were determined. The size and composition of atherosclerotic plaques were measured by en face analysis, Movat staining and immunohistochemistry. The phosphorylation of SHP2 and related signaling molecules was analyzed by Western blot. Mechanistic analyses were performed in oxLDL-stimulated cultured vascular smooth muscle cells (VSMCs) with or without 10 mM PHPS1 pretreatment. Protein phosphorylation levels were detected by Western blot, and VSMC proliferation was assessed by BrdU staining.

RESULTS

PHPS1 decreased the number of atherosclerotic plaques without significantly affecting body weight, serum glucose levels or lipid metabolism. Plaque composition analysis showed a significant decrease in the number of VSMCs in atherosclerotic lesions of Ldlr-/- mice treated with PHPS1. Stimulation with oxLDL induced a dose-dependent increase in the number of VSMCs and in SHP2 and ERK phosphorylation levels, and these effects were blocked by PHPS1.

CONCLUSION

The SHP2 inhibitor PHPS1 exerts a protective effect against atherosclerosis by reducing VSMC proliferation via SHP2/ERK pathway activation.

Whey Protein Attenuates Angiotensin II-Primed Premature Senescence of Vascular Smooth Muscle Cells through Upregulation of SIRT1

Whey protein, a by-product of milk curdling, exhibits diverse biological activities and is used as a dietary supplement. However, its effects on stress-induced vascular aging have not yet been elucidated. In this study, we found that whey protein significantly inhibited the Ang II-primed premature senescence of vascular smooth muscle cells (VSMCs). In addition, we observed a marked dose- and time-dependent increase in SIRT1 promoter activity and mRNA in VSMCs exposed to whey protein, accompanied by elevated SIRT1 protein expression. Ang II-mediated repression of SIRT1 level was dose-dependently reversed in VSMCs treated with whey protein, suggesting that SIRT1 is involved in preventing senescence in response to this treatment. Furthermore, resveratrol, a well-defined activator of SIRT1, potentiated the effects of whey protein on Ang II-primed premature senescence, whereas sirtinol, an inhibitor of SIRT1, exerted the opposite. Taken together, these results indicated that whey protein-mediated upregulation of SIRT1 exerts an anti-senescence effect, and can thus ameliorate Ang IIinduced vascular aging as a dietary supplement.

Estrogen modulates vascular smooth muscle cell function through downregulation of SIRT1

Background

There are sex differences in the incidence and severity of cardiovascular disease. Although an estrogen-mediated vasculoprotective effect is widely accepted, clinical trial results have been conflicting and the detailed mechanisms are still unclear. Sirtuin 1 (SIRT1), a class III histone deacetylase, may protect against vascular aging and atherosclerosis; however, the effects of estrogen on SIRT1 expression and vascular smooth muscle cell (VSMC) behavior remain unknown.

Materials and Methods

We ovariectomized (OVX) female, wild-type, C57BL/6J mice, which were randomized into non-estrogen- and estrogen-supplemented groups. We also treated A7r5 VSMCs with 17-β-estradiol and resveratrol, a SIRT1 activator, in vitro, and measured the expression of SIRT1 and apoptotic markers, as well as proliferation, viability, and migration.

Results

Aortic tissue from OVX mice exhibited marked VSMC hyperplasia and upregulation of SIRT1, which was reversed by 17-β-estradiol supplementation, as assessed by western blotting and immunohistochemical staining. In vitro, 17-β-estradiol downregulated SIRT1 expression in a dose- and time-dependent manner, increased apoptosis, and reduced proliferation, viability, and migration. Resveratrol reversed these effects through the activation of SIRT1. Estrogen appeared to mediate its effects through the Akt and ERK pathways.

Conclusions

Estrogen may regulate cardiovascular health via the expression of SIRT1, possibly through the AKT and ERK signaling pathways.

High glucose upregulates endothelin type B receptors in vascular smooth muscle cells via the downregulation of Sirt1

Silent information regulator family protein 1 (Sirt1) has recently gained attention for its protective effects against diabetic and cardiovascular diseases (CVDs). Vascular smooth muscle endothelin type B (ETB) receptors are involved in the pathogenesis of CVDs and diabetes. The aim of present study was to explore whether Sirt1 is involved in high glucose (HG)-mediated regulation of ETB receptors in rat superior mesenteric arteries (SMA). The rat SMA segments were cultured in the presence and absence of HG with or without the activator of Sirt1 and specific inhibitor for the extracellular signal-regulated protein kinase 1/2 (ERK1/2) for 24 h. Following organ culture, the contractile responses to sarafotoxin 6c were studied using a sensitive myograph, and the ETB receptor protein expression level was determined using western blotting. The results demonstrated that HG induced upregulation of ETB receptor expression and increased receptor-mediated vasoconstriction in SMA. Resveratrol (Res; a Sirt1 activator) concentration-dependently inhibited the HG-induced upregulation of ETB receptor expression and receptor-mediated vasoconstriction. Additionally, these effects could also be abolished by an inhibitor of the ERK1/2 signaling pathway. Furthermore, upregulation of ERK1/2 phosphorylation induced by HG was inhibited by Res. In conclusion, HG upregulated ETB receptors by downregulating Sirt1 and subsequently activating the ERK1/2 signaling pathways in the organ culture SMA.

SIRT1 suppresses colorectal cancer metastasis by transcriptional repression of miR-15b-5p

The class III deacetylase sirtuin 1 (SIRT1), a member of the sirtuin family proteins, plays a key role in many types of cancers including colorectal cancer (CRC). Here we report that SIRT1 suppressed CRC metastasis in vitro and in vivo as a negative regulator for miR-15b-5p transcription. Mechanistically, SIRT1 impaired regulatory effects of activator protein (AP-1) on miR-15b-5p trans-activation through deacetylation of AP-1. Importantly, acyl-CoA oxidase 1 (ACOX1), a key enzyme of the fatty acid oxidation (FAO) pathway, was found as a direct target for miR-15b-5p. SIRT1 expression was positively correlated with ACOX1 expression in CRC cells and in xenografts. Moreover, ACOX1 overexpression attenuated the augmentation of migration and invasion of CRC cells by miR-15b-5p overexpression. In conclusion, our study demonstrated a functional role of the SIRT1/miR-15b-5p/ACOX1 axis in CRC metastasis and suggested a potential target for metastatic CRC therapy.

Homocysteine up-regulates endothelin type A receptor in vascular smooth muscle cells through Sirt1/ERK1/2 signaling pathway

Sirtuin 1 (Sirt1) is a longevity gene that has protective effects in cardiovascular diseases (CVDs). The endothelin type A (ET_A) receptor is involved in pathogenesis of CVDs. The extracellular signal related kinases 1 and 2 (ERK1/2) signaling pathway is involved in regulation of the ET_A receptor induced by some CVD risk factors in vascular smooth muscle cells (VSMCs). Hyperhomocysteinemia (HHcy) is an independent risk factor for CVDs. The present study was designed to investigate the hypothesis that homocysteine up-regulates ET_A receptor through the Sirt1/ERK1/2 signaling pathway. In vitro experiments were performed in the rat superior mesenteric artery. The rat superior mesenteric artery was cultured with or without homocysteine (Hcy) in the presence and absence of Resveratrol (Res, a Sirt1 agonist), SRT1720 (a specific Sirt1 agonist) or U0126 (an ERK1/2 signaling pathway inhibitor) in serum-free medium for 24h. In vivo, the rats received subcutaneous injections of Hcy in the presence of or absence of Res or U0126 for 3weeks. The contractile response to ET-1 was studied using a sensitive myograph. In addition, the level of protein expression was determined using western blotting. Hcy significantly increased the expression of ET_A receptor and also increased the ET_A receptor-mediated contractile response induced by ET-1 in vitro. These effects were inhibited by Res, SRT1720 and U0126 treatment. In addition, Hcy down-regulated the level of Sirt1, and up-regulated the level of phosphorylated ERK1/2, which was reversed upon Res or SRT1720 treatment. In vivo results showed that HHcy results in the up-regulation of ET_A receptor expression, and elevated blood pressure in rats. However, Res and U0126 could block these effects, respectively. In conclusion, these results suggest that Hcy regulates ET_A receptor expression via the Sirt1/ERK1/2 signaling pathway in VSMCs.

Sirt1 Inhibits Oxidative Stress in Vascular Endothelial Cells

The vascular endothelium is a layer of cells lining the inner surface of vessels, serving as a barrier that mediates microenvironment homeostasis. Deterioration of either the structure or function of endothelial cells (ECs) results in a variety of cardiovascular diseases. Previous studies have shown that reactive oxygen species (ROS) is a key factor that contributes to the impairment of ECs and the subsequent endothelial dysfunction. The longevity regulator Sirt1 is a NAD⁺-dependent deacetylase that has a potential antioxidative stress activity in vascular ECs. The mechanisms underlying the protective effects involve Sirt1/FOXOs, Sirt1/NF-κB, Sirt1/NOX, Sirt1/SOD, and Sirt1/eNOs pathways. In this review, we summarize the most recent reports in this field to recapitulate the potent mechanisms involving the protective role of Sirt1 in oxidative stress and to highlight the beneficial effects of Sirt1 on cardiovascular functions.