Suppression of EC-SOD by oxLDL During Vascular Smooth Muscle Cell Proliferation

Key ingredients in Verbena officinalis and determination of their anti-atherosclerotic effect using a computer-aided drug design approach

Lipid metabolism disorders may considerably contribute to the formation and development of atherosclerosis (AS). Traditional Chinese medicine has received considerable attention in recent years owing to its ability to treat lipid metabolism disorders using multiple components and targets. Verbena officinalis (VO), a Chinese herbal medicine, exhibits anti-inflammatory, analgesic, immunomodulatory, and neuroprotective effects. Evidence suggests that VO regulates lipid metabolism; however, its role in AS remains unclear. In the present study, an integrated network pharmacology approach, molecular docking, and molecular dynamics simulation (MDS) were applied to examine the mechanism of VO against AS. Analysis revealed 209 potential targets for the 11 main ingredients in VO. Further, 2698 mechanistic targets for AS were identified, including 147 intersection targets between VO and AS. Quercetin, luteolin, and kaempferol were considered key ingredients for the treatment of AS based on a potential ingredient target-AS target network. GO analysis revealed that biological processes were primarily associated with responses to xenobiotic stimuli, cellular responses to lipids, and responses to hormones. Cell components were predominantly focused on the membrane microdomain, membrane raft, and caveola nucleus. Molecular functions were mainly focused on DNA-binding transcription factor binding, RNA polymerase II-specific DNA-binding transcription factor binding, and transcription factor binding. KEGG pathway enrichment analysis identified pathways in cancer, fluid shear stress, and atherosclerosis, with lipid and atherosclerosis being the most significantly enriched pathways. Molecular docking revealed that three key ingredients in VO (i.e., quercetin, luteolin, and kaempferol) strongly interacted with three potential targets (i.e., AKT1, IL-6, and TNF-α). Further, MDS revealed that quercetin had a stronger binding affinity for AKT1. These findings suggest that VO has beneficial effects on AS via these potential targets that are closely related to the lipid and atherosclerosis pathways. Our study utilized a new computer-aided drug design to identify key ingredients, potential targets, various biological processes, and multiple pathways associated with the clinical roles of VO in AS, which provides a comprehensive and systemic pharmacological explanation for the anti-atherosclerotic activity of VO.

Extracellular-superoxide dismutase DNA methylation promotes oxidative stress in homocysteine-induced atherosclerosis

In the present study, we investigate the effect of homocysteine (Hcy) on extracellular-superoxide dismutase (EC-SOD) DNA methylation in the aorta of mice, and explore the underlying mechanism in macrophages, trying to identify the key targets of Hcy-induced EC-SOD methylation changes. ApoE ^-/- mice are fed different diets for 15 weeks, EC-SOD and DNA methyltransferase 1 (DNMT1) expression levels are detected by RT-PCR and western blot analysis. EC-SOD methylation levels are assessed by ntMS-PCR. After EC-SOD overexpression or knockdown in macrophages, following the transfection of macrophages with pEGFP-N1-DNMT1, the methylation levels of EC-SOD are detected. Our data show that the concentrations of Hcy and the area of atherogenic lesions are significantly increased in ApoE ^-/- mice fed with a high-methionine diet, and have a positive correlation with the levels of superoxide anions, which indicates that Hcy-activated superoxide anions enhance the development of atherogenic lesions. EC-SOD expression is suppressed by Hcy, and the content of superoxide anion is increased when EC-SOD is silenced by RNAi in macrophages, suggesting that EC-SOD plays a major part in oxidative stress induced by Hcy. Furthermore, the promoter activity of EC-SOD is increased following transfection with the -1/-1100 fragment, and EC-SOD methylation level is significantly suppressed by Hcy, and more significantly decreased upon DNMT1 overexpression. In conclusion, Hcy may alter the DNA methylation status and DNMT1 acts as the essential enzyme in the methyl transfer process to disturb the status of EC-SOD DNA methylation, leading to decreased expression of EC-SOD and increased oxidative stress and atherosclerosis.

Persistent myopathy despite release of partial obstruction: in vivo reversal of dysfunction and transcriptional responses using rapamycin

Current and potential medical therapy for obstruction-induced myopathic bladder dysfunction (from benign prostatic hyperplasia or posterior urethral valves) focuses on symptoms. The persistent tissue pathology and dysfunction after release of obstruction is often deemed irreversible without any systematic therapeutic approaches. As rapamycin can attenuate bladder smooth muscle hypertrophy and dysfunction during the genesis of partial obstruction in vivo, we tested whether rapamycin could improve persistent function after release of obstruction (de-obstruction or REL). Female Sprague-Dawley rat bladders were partially obstructed (PBO) by suturing around both the urethra and a para-urethral steel rod, then removing the rod. One day prior to release of obstruction (preREL), voiding parameters and residual urine volume of preREL+future rapa, preREL+future veh groups were recorded. Release of obstruction (REL) was performed by suture removal following 6 weeks of PBO. For 4 more weeks after the de-obstruction, REL animals were randomized to rapamycin (REL+rapa) or vehicle (REL+veh). PBO for 6 weeks were used as positive controls. In shams, the urethra was exposed, but no suture tied. Voiding parameters and residual urine volume were measured prior to sacrifice of sham and REL+veh or REL+rapa, and PBO. Rapamycin efficacy was tested by pair-wise comparison of changes in individual voiding data from preREL+future veh or preREL+future rapa versus REL+veh or REL+rapa, respectively, as well as by comparisons of REL+veh to REL+rapa groups. Bladders were weighed and processed for a high-throughput QPCR array, and histopathology. Bladder/body mass ratios with PBO increased significantly and remained higher in the release phase in REL+veh animals. REL+rapa versus REL+veh improved residual volumes and micturition fractions toward sham levels. Three genes encoding extracellular proteins, BMP2, SOD3, and IGFBP7, correlated with functional improvement by Pearson's correlations. The promoters of these genes showed enrichment for several motifs including circadian E-boxes. While obstruction and REL augmented CLOCK and NPAS2 expression above sham levels, rapamycin treatment during release significantly blocked their expression. This experimental design of pharmaco-intervention during the de-obstruction phase revealed a novel pathway dysregulated during the clinically relevant treatment phase of obstructive bladder myopathy.

Trimetazidine Protects Against Atherosclerosis by Changing Energy Charge and Oxidative Stress

BACKGROUND This study investigated the effect and the possible mechanism of trimetazidine in atherosclerosis. MATERIAL AND METHODS We established an atherosclerotic rat model by high-fat diet and vitamin D injection. Rats were separated into 3 different groups: control, atherosclerosis, and trimetazidine (n=10). The aortic artery was isolated and its morphological features were examined by hematoxylin and eosin (HE) staining. Serum low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC), and triglycerides (TG) were analyzed using an automatic biochemical analyzer. Human aortic smooth muscle cells (HASMCs) were cultured and divided into 5 groups: no treatment, H₂O₂ treatment only, trimetazidine preincubation before H₂O₂ treatment, oxidized low-density lipoprotein (oxLDL) treatment only, and trimetazidine preincubation before oxLDL treatment. HASMCs proliferation was tested using the Cell Counting Kit-8. Reactive oxygen species (ROS) and malondialdehyde (MDA) levels, superoxide dismutase (SOD) activity of the aortic artery, and HASMCs were measured using commercially available kits. RESULTS HE staining assay showed that trimetazidine suppressed the progression of atherosclerosis and reduced foam cell formation in the aortic artery without affecting serum lipid levels. HASMCs proliferation assay revealed that trimetazidine alleviated the inhibitory effect of H₂O₂ on HASMCs proliferation and inhibited oxLDL-induced proliferation of HASMCs. Moreover, trimetazidine ameliorated ROS up-regulation elicited by H₂O₂ or oxLDL in HASMCs. Additionally, trimetazidine restored SOD activity and reduced MDA content of HASMCs. CONCLUSIONS Trimetazidine suppressed the progression of atherosclerosis by enhancing energy value, decreasing ROS level of aortic artery, modulating HASMCs proliferation, and reducing oxidative stress in HASMCs.

Lipoproteins and Cardiovascular Redox Signaling: Role in Atherosclerosis and Coronary Disease

SIGNIFICANCE

Lipoproteins, such as low-density lipoprotein, play a causal role in the development of atherosclerosis and coronary disease. Recent Advances: Lipoproteins can stimulate vascular production of reactive oxygen species, which act as important signaling molecules in the cardiovascular system contributing to the pathophysiology of endothelial dysfunction, hypertension, and atherosclerosis.

CRITICAL ISSUES

Modified lipoproteins have emerged as important regulators of redox signaling, such as oxidized or carbamylated low-density lipoprotein or modified high-density lipoproteins, that contain oxidized lipids, an altered protein cargo, and associated small molecules, such as symmetric dimethylarginine.

FUTURE DIRECTIONS

In this review, we provide an overview on signaling pathways stimulated by modified lipoproteins in the cardiovascular system and their potential role in cardiovascular disease development. Moreover, we highlight novel aspects of how gut microbiome-related mechanisms-a growing research field-may contribute to lipoprotein modification with subsequent impact on cardiovascular redox signaling. Antioxid. Redox Signal. 29, 337-352.

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.

Exercise intervention attenuates hyperhomocysteinemia-induced aortic endothelial oxidative injury by regulating SIRT1 through mitigating NADPH oxidase/LOX-1 signaling

Coronary artery disease (CAD) is a critical cardiovascular disease and a cause of high morbidity and mortality in this world. Hyperhomocysteinemia (HHcy) has been suggested as a risk factor for CAD. In addition, SIRT1 (sirtuin 1) has been reported to play a protective role in a variety of diseases, especially in the cardiovascular system. The main purpose of this study was to investigate the effects of exercise training on apoptosis and inflammation in HHcy animals. We also tested whether exercise protected against Hhcy-induced dysfunction of endothelium through modulation of SIRT1. C57BL mice (8 in each group) were fed with or without 1% L-methionine (w/w) in water for 4 months to induce HHcy. We found that Hhcy repressed SIRT1 and AMPK expression and increased NADPH oxidase activity. Plasma MDA, endothelium LOX-1 and p-p38 were up-regulated by Hhcy induction. NF-κB and it downstream molecules were activated under Hhcy situation, thereby promoting pro-inflammatory responses. Moreover, we also reported that Hhcy caused endothelium apoptosis involving Akt inhibition and mitochondria-dependent apoptotic pathways. Exercise training significantly protected against endothelium from Hhcy caused oxidative injuries. In addition, EX527 (SIRT1 inhibitor) reduced the therapeutic effects by exercise. Our results had indicated that exercise training prevent the development of atherosclerosis through SIRT1 activation and oxidative stress inhibition under Hhcy situation.

Polyphenols from Ilex latifolia Thunb. (a Chinese bitter tea) exert anti-atherosclerotic activity through suppressing NF-κB activation and phosphorylation of ERK1/2 in macrophages

Ilex latifolia Thunb is a kind of herbal tea and widely consumed as a functional tea beverage in Asian countries. In this study, polyphenols were extracted from I. latifolia and the major compounds were identified by liquid chromatography-mass spectrometry (LC-MS), then the effect on oxidized low-density lipoprotein (ox-LDL)-induced macrophage foam cell formation was investigated. Results showed that the polyphenols could significantly inhibit ox-LDL-induced macrophage foam cell formation and suppress lipid droplet accumulation and cholesterol uptake in RAW 264.7 cells. Additionally, the secretion of pro-inflammatory cytokines, such as tumor necrosis factor (TNF-α), interleukin (IL)-1β, IL-6 and inducible nitric oxide synthase (iNOS), was significantly inhibited. Moreover, the polyphenols could suppress the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and clusters of differentiation 36 (CD 36), which were receptors for ox-LDL. Mechanistically, I. latifolia polyphenols could inhibit macrophage foam cell formation by suppressing NF-κB activation and phosphorylation of ERK1/2.

LOX-1 mediated phenotypic switching of pulmonary arterial smooth muscle cells contributes to hypoxic pulmonary hypertension

In pulmonary hypertension (PH), pulmonary arterial smooth muscle cells (PASMCs) are dedifferentiated, undergoing a contractile-to-synthetic phenotypic switching. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) plays diverse roles in the cardiovascular system, but its contribution to PH remains to be fully defined. The present study was undertaken to explore the role of LOX-1 in PASMCs dedifferentiation in hypoxia-induced pulmonary vascular remodeling and PH. In a rat model of hypoxic PH, pulmonary vascular remodeling was accompanied by increased expression of LOX-1 in pulmonary arteries. In primary rat PASMCs, hypoxia-induced PASMCs dedifferentiation occurred concomitantly with LOX-1 upregulation. Inhibition of LOX-1 by either siRNA knockdown or neutralizing antibody significantly ameliorated PASMCs dedifferentiation. Mechanistically, LOX-1 promotes PASMCs dedifferentiation under hypoxic conditions via ERK1/2-Elk-1/MRTF-A/SRF signaling pathway. In conclusion, our data uncovers an important role of LOX-1 in the maintenance of PASMCs phenotype. Therapeutic targeting of LOX-1/ERK1/2-Elk-1/MRTF-A/SRF signaling axis would be exploited to treat hypoxic PH.

SIRT1 inhibition causes oxidative stress and inflammation in patients with coronary artery disease

Coronary artery disease (CAD) is the primary critical cardiovascular event. Endothelial cell and monocyte dysfunction with subsequent extravagant inflammation are the main causes of vessel damage in CAD. Thus, strategies that repress cell death and manage unsuitable pro-inflammatory responses in CAD are potential therapeutic strategies for improving the clinical prognosis of patients with CAD. SIRT1 (Sirtuin 1) plays an important role in regulating cellular physiological processes. SIRT1 is also thought to protect the cardiovascular system by means of its antioxidant, anti-inflammation and anti-apoptosis activities. In the present study, we found that the SIRT1 expression levels were repressed and the acetylated p53 expression levels were enhanced in the monocytes of patients with CAD. LOX-1/oxidative stress was also up-regulated in the monocytes of patients with CAD, thereby increasing pro-apoptotic events and pro-inflammatory responses. We also demonstrated that monocytes from CAD patients caused endothelial adhesion molecule activation and the adherence of monocytes and endothelial cells. Our findings may explain why CAD patients remain at an increased risk of long-term recurrent ischemic events and provide new knowledge regarding the management of clinical CAD patients.

The anti-proliferative effects of oleanolic acid on A7r5 cells-Role of UCP2 and downstream FGF-2/p53/TSP-1

Vascular smooth muscle cell (VSMC) proliferation is a major contributor to atherosclerosis. This study investigated the inhibitory effects of oleanolic acid (OA) against oxidized low-density lipoprotein (ox-LDL)-induced VSMC proliferation in A7r5 cells and explored underlying molecular mechanism. The cell proliferation was quantified with cell counting kit-8 (CCK-8), in which ox-LDL significantly increased A7r5 cells proliferation, while OA pretreatment effectively alleviated such changes without inducing overt cytotoxicity, as indicated by lactate dehydrogenase (LDH) assay. Quantitative real-time RT-PCR (qRT-PCR) and Western blotting revealed increased UCP2 and FGF-2 expression levels as well as decreased p53 and TSP-1 expression levels in A7r5 cells following ox-LDL exposure, while OA pretreatment reversed such changes. Furthermore, inhibiting UCP2 with genipin remarkably reversed the changes in the expression levels of FGF-2, p53, and TSP-1 induced by ox-LDL exposure; silencing FGF-2 with siRNA did not significantly change the expression levels of UCP2 but effectively reversed the changes in the expression levels of p53 and TSP-1, and activation of p53 with PRIMA-1 only significantly affected the changes in the expression levels of TSP-1, but not in UCP2 or FGF-2, suggesting a UCP-2/FGF-2/p53/TSP-1 signaling in A7r5 cells response to ox-LDL exposure. Additionally, co-treatment of OA and genipin exhibited similar effects to the expression levels of UCP2, FGF-2, p53, and TSP-1 as OA or genipin solo treatment in ox-LDL-exposed A7r5 cells, suggesting the involvement of UCP-2/FGF-2/p53/TSP-1 in the mechanism of OA. In conclusion, OA inhibits ox-LDL-induced VSMC proliferation in A7r5 cells, the mechanism involves the changes in UCP-2/FGF-2/p53/TSP-1.

CAPE increases the expression of SOD3 through epigenetics in human retinal endothelial cells

Extracellular-superoxide dismutase (EC-SOD or SOD3), which catalyzes the dismutation of superoxide anions into hydrogen peroxide, plays a key role in vascular protection against reactive oxygen species (ROS). The excess generation of ROS is closely involved in the pathogenesis of diabetic retinopathy (DR); therefore, the maintenance of SOD3 expression at high levels is important for the prevention of DR. In the present study, we showed that caffeic acid phenethyl ester (CAPE) increased the expression of SOD3 through the acetylation of histone within the SOD3 promoter region in human retinal endothelial cells (HRECs). Histone acetylation within its promoter was focused on the inhibition of histone deacetylase (HDAC), and we examined the involvement of myocyte enhancer factor 2 (MEF2) and HDAC1 in CAPE-elicited SOD3 expression. Our results demonstrate that SOD3 silencing in basal HRECs is regulated by HDAC1 composed with MEF2A/2D hetero dimers. Moreover, phosphorylation of threonine 312 in MEF2A and dissociation of HDAC1 from SOD3 promoter play pivotal roles in CAPE-elicited SOD3 expression. Overall, our findings provide that CAPE may be one of the seed compounds that maintain redox homeostasis.

Hyperoside inhibits the effects induced by oxidized low-density lipoprotein in vascular smooth muscle cells via oxLDL-LOX-1-ERK pathway

Hyperoside is a major active constituent in many medicinal plants traditionally used in Chinese medicines for their anti-inflammatory, antioxidative, and vascular protective effects. Recent studies have focused on the protective effects of hyperoside on hyperlipidemia. However, the molecular mechanisms underlying these effects are unknown. In this study, vascular smooth muscle cells (VSMCs) were treated in vitro with oxidized low-density lipoprotein (oxLDL) in the presence or absence of hyperoside. Western blotting, quantitative PCR, and tetrazolium assay were used to detect lectin-like oxLDL receptor-1 (LOX-1) expression and extracellular signal-regulated kinases (ERK) activation, and to determine VSMCs viability. The results demonstrated that oxLDL promoted LOX-1 expression, ERK activation, and proliferation in VSMCs. Hyperoside significantly inhibited the oxLDL-stimulated effects after long time exposure. However, it promoted ERK activation directly following a short incubation duration (25 min). In conclusion, hyperoside inhibits oxLDL-induced LOX-1 expression, ERK activation, and cell proliferation through the oxLDL-LOX-1-ERK pathway in VSMCs. Our findings suggest a novel role of hyperoside in treating and preventing atherosclerosis.