Thrombin and NAD(P)H oxidase-mediated regulation of CD44 and BMP4-Id pathway in VSMC, restenosis, and atherosclerosis

Mechanisms modulating foam cell formation in the arterial intima: exploring new therapeutic opportunities in atherosclerosis

In recent years, the role of macrophages as the primary cell type contributing to foam cell formation and atheroma plaque development has been widely acknowledged. However, it has been long recognized that diffuse intimal thickening (DIM), which precedes the formation of early fatty streaks in humans, primarily consists of lipid-loaded smooth muscle cells (SMCs) and their secreted proteoglycans. Recent studies have further supported the notion that SMCs constitute the majority of foam cells in advanced atherosclerotic plaques. Given that SMCs are a major component of the vascular wall, they serve as a significant source of microvesicles and exosomes, which have the potential to regulate the physiology of other vascular cells. Notably, more than half of the foam cells present in atherosclerotic lesions are of SMC origin. In this review, we describe several mechanisms underlying the formation of intimal foam-like cells in atherosclerotic plaques. Based on these mechanisms, we discuss novel therapeutic approaches that have been developed to regulate the generation of intimal foam-like cells. These innovative strategies hold promise for improving the management of atherosclerosis in the near future.

Flow-induced reprogramming of endothelial cells in atherosclerosis

Atherosclerotic diseases such as myocardial infarction, ischaemic stroke and peripheral artery disease continue to be leading causes of death worldwide despite the success of treatments with cholesterol-lowering drugs and drug-eluting stents, raising the need to identify additional therapeutic targets. Interestingly, atherosclerosis preferentially develops in curved and branching arterial regions, where endothelial cells are exposed to disturbed blood flow with characteristic low-magnitude oscillatory shear stress. By contrast, straight arterial regions exposed to stable flow, which is associated with high-magnitude, unidirectional shear stress, are relatively well protected from the disease through shear-dependent, atheroprotective endothelial cell responses. Flow potently regulates structural, functional, transcriptomic, epigenomic and metabolic changes in endothelial cells through mechanosensors and mechanosignal transduction pathways. A study using single-cell RNA sequencing and chromatin accessibility analysis in a mouse model of flow-induced atherosclerosis demonstrated that disturbed flow reprogrammes arterial endothelial cells in situ from healthy phenotypes to diseased ones characterized by endothelial inflammation, endothelial-to-mesenchymal transition, endothelial-to-immune cell-like transition and metabolic changes. In this Review, we discuss this emerging concept of disturbed-flow-induced reprogramming of endothelial cells (FIRE) as a potential pro-atherogenic mechanism. Defining the flow-induced mechanisms through which endothelial cells are reprogrammed to promote atherosclerosis is a crucial area of research that could lead to the identification of novel therapeutic targets to combat the high prevalence of atherosclerotic disease.

Identification of prognostic and diagnostic signatures for cancer and acute myocardial infarction: multi-omics approaches for deciphering heterogeneity to enhance patient management

Patients diagnosed with cancer face an increased risk of cardiovascular events in the short term, while those experiencing acute myocardial infarction (AMI) have a higher incidence of cancer. Given limitations in clinical resources, identifying shared biomarkers offers a cost-effective approach to risk assessment by minimizing the need for multiple tests and screenings. Hence, it is crucial to identify common biomarkers for both cancer survival and AMI prediction. Our study suggests that monocyte-derived biomarkers, specifically WEE1, PYHIN1, SEC61A2, and HAL, hold potential as predictors for cancer prognosis and AMI. We employed a novel formula to analyze mRNA levels in clinical samples from patients with AMI and cancer, resulting in the development of a new risk score based on expression profiles. By categorizing patients into high-risk and low-risk groups based on the median risk score, we observed significantly poorer overall survival among high-risk patients in cancer cohorts using Kaplan-Meier analysis. Furthermore, calibration curves, decision curve analysis (DCA), and clinical impact curve analyses provided additional evidence supporting the robust diagnostic capacity of the risk score for AMI. Noteworthy is the shared activation of the Notch Signaling pathway, which may shed light on common high-risk factors underlying both AMI and cancer. Additionally, we validated the differential expression of these genes in cell lines and clinical samples, respectively, reinforcing their potential as meaningful biomarkers. In conclusion, our study demonstrates the promise of mRNA levels as biomarkers and emphasizes the significance of further research for validation and refinement.

Mechanisms of Small Intestine Involvement in Obesity-Induced Atherosclerosis

Purpose

Studies have shown that atherosclerotic plaques are associated with changes in the microbial composition of the intestinal flora and obesity, and that the small intestine plays an irreplaceable role in regulating intestinal flora homeostasis, but the role of the small intestine in the development of obesity-related atherosclerosis remains understudied. Therefore, this study explores the role of the small intestine in obesity-induced atherosclerosis and its molecular mechanisms.

Methods

In the GSE59054 data, small intestine tissue samples from 3 normal and 3 obese mice were analyzed using bioinformatics methods. Screening for differentially expressed genes (DEGs) using the GEO2R tool. The DEGs were next processed for bioinformatics analysis. We constructed an obese mouse model and measured aortic arch pulse wave velocity (PWV). Aortic and small intestine tissues were stained with hematoxylin-eosin (HE) to observe pathological changes. Finally, immunohistochemistry was performed to verify the expression of small intestinal proteins.

Results

We identified a total of 122 DEGs. Pathway analysis revealed that BMP4, CDH5, IL1A, NQO1, GSTM1, GSTA3, CAV1 and MGST2 were mainly enriched in the Fluid shear stress and atherosclerosis pathway. In addition, BMP4, NQO1 and GSTM1 are closely related to atherosclerosis. Ultrasound and pathological findings suggest the presence of obesity atherosclerosis. Immunohistochemistry verified high expression of BMP4 and low expression of NQO1 and GSTM1 in obese small intestine tissues.

Conclusion

The altered expression of BMP4, NQO1 and GSTM1 in small intestine tissues during obesity may be related to atherosclerosis, and Fluid shear stress and atherosclerosis pathway may be the molecular mechanism of their role.

Regulation of Adenine Nucleotide Metabolism by Adenylate Kinase Isozymes: Physiological Roles and Diseases

Adenylate kinase (AK) regulates adenine nucleotide metabolism and catalyzes the ATP + AMP ⇌ 2ADP reaction in a wide range of organisms and bacteria. AKs regulate adenine nucleotide ratios in different intracellular compartments and maintain the homeostasis of the intracellular nucleotide metabolism necessary for growth, differentiation, and motility. To date, nine isozymes have been identified and their functions have been analyzed. Moreover, the dynamics of the intracellular energy metabolism, diseases caused by AK mutations, the relationship with carcinogenesis, and circadian rhythms have recently been reported. This article summarizes the current knowledge regarding the physiological roles of AK isozymes in different diseases. In particular, this review focused on the symptoms caused by mutated AK isozymes in humans and phenotypic changes arising from altered gene expression in animal models. The future analysis of intracellular, extracellular, and intercellular energy metabolism with a focus on AK will aid in a wide range of new therapeutic approaches for various diseases, including cancer, lifestyle-related diseases, and aging.

Genome-Wide Transcriptional Profiling Reveals PHACTR1 as a Novel Molecular Target of Resveratrol in Endothelial Homeostasis

Atherosclerosis is a chronic inflammatory vascular disease in which endothelial cells play an important role in maintaining vascular homeostasis. Endotheliitis caused by endothelial dysfunction (ED) is the key cause for the development of cardiovascular and cerebrovascular diseases as well as other vascular system diseases. Resveratrol (RES), a multi-functional polyphenol present in edible plants and fruits, prevents cardiovascular disease by regulating a variety of athero-relevant signaling pathways. By transcriptome profiling of RES-treated human umbilical vein endothelial cells (HUVECs) and in-depth bioinformatic analysis, we observed that differentially expressed genes (DEGs) were enriched in KEGG pathways of fluid shear stress and atherosclerosis, suggesting that the RES may serve as a good template for a shear stress mimetic drug that hold promise in combating atherosclerosis. A heat map and multiple datasets superimposed screening revealed that RES significantly down-regulated phosphatase and actin modulator 1 (PHACTR1), a pivotal coronary artery disease risk gene associated with endothelial inflammation and polyvascular diseases. We further demonstrate that RES down-regulated the gene and protein expression of PHACTR1 and inhibited TNF-α-induced adhesion of THP-1 monocytes to activated endothelial cells via suppressing the expression of PHACTR1. Taken together, our study reveals that PHACTR1 represents a new molecular target for RES to maintain endothelial cell homeostasis and prevent atherosclerotic cardiovascular disease.

Induction of ferroptosis promotes vascular smooth muscle cell phenotypic switching and aggravates neointimal hyperplasia in mice

BACKGROUND

Stent implantation-induced neointima formation is a dominant culprit in coronary artery disease treatment failure after percutaneous coronary intervention. Ferroptosis, an iron-dependent regulated cell death, has been associated with various cardiovascular diseases. However, the effect of ferroptosis on neointima formation remains unclear.

METHODS

The mouse common right carotid arteries were ligated for 16 or 30 days, and ligated tissues were collected for further analyses. Primary rat vascular smooth muscle cells (VSMCs) were isolated from the media of aortas of Sprague-Dawley (SD) rats and used for in vitro cell culture experiments.

RESULTS

Ferroptosis was positively associated with neointima formation. In vivo, RAS-selective lethal 3 (RSL3), a ferroptosis activator, aggravated carotid artery ligation-induced neointima formation and promoted VSMC phenotypic conversion. In contrast, a ferroptosis inhibitor, ferrostatin-1 (Fer-1), showed the opposite effects in mice. In vitro, RSL3 promoted rat VSMC phenotypic switching from a contractile to a synthetic phenotype, evidenced by increased contractile markers (smooth muscle myosin heavy chain and calponin 1), and decreased synthetic marker osteopontin. The induction of ferroptosis by RSL3 was confirmed by the increased expression level of ferroptosis-associated gene prostaglandin-endoperoxide synthase 2 (Ptgs2). The effect of RSL3 on rat VSMC phenotypic switching was abolished by Fer-1. Moreover, N-acetyl-L-cysteine (NAC), the reactive oxygen species inhibitor, counteracted the effect of RSL3 on the phenotypic conversion of rat VSMCs.

CONCLUSIONS

Ferroptosis induces VSMC phenotypic switching and accelerates ligation-induced neointimal hyperplasia in mice. Our findings suggest inhibition of ferroptosis as an attractive strategy for limiting vascular restenosis.

NADPH Oxidases in Diastolic Dysfunction and Heart Failure with Preserved Ejection Fraction

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases regulate production of reactive oxygen species (ROS) that cause oxidative damage to cellular components but also regulate redox signaling in many cell types with essential functions in the cardiovascular system. Research over the past couple of decades has uncovered mechanisms by which NADPH oxidase (NOX) enzymes regulate oxidative stress and compartmentalize intracellular signaling in endothelial cells, smooth muscle cells, macrophages, cardiomyocytes, fibroblasts, and other cell types. NOX2 and NOX4, for example, regulate distinct redox signaling mechanisms in cardiac myocytes pertinent to the onset and progression of cardiac hypertrophy and heart failure. Heart failure with preserved ejection fraction (HFpEF), which accounts for at least half of all heart failure cases and has few effective treatments to date, is classically associated with ventricular diastolic dysfunction, i.e., defects in ventricular relaxation and/or filling. However, HFpEF afflicts multiple organ systems and is associated with systemic pathologies including inflammation, oxidative stress, arterial stiffening, cardiac fibrosis, and renal, adipose tissue, and skeletal muscle dysfunction. Basic science studies and clinical data suggest a role for systemic and myocardial oxidative stress in HFpEF, and evidence from animal models demonstrates the critical functions of NOX enzymes in diastolic function and several HFpEF-associated comorbidities. Here, we discuss the roles of NOX enzymes in cardiovascular cells that are pertinent to the development and progression of diastolic dysfunction and HFpEF and outline potential clinical implications.

Mitochondrial reactive oxygen is critical for IL-12/IL-18-induced IFN-γ production by CD4+ T cells and is regulated by Fas/FasL signaling

Mitochondrial activation and the production of mitochondrial reactive oxygen species (mROS) are crucial for CD4⁺ T cell responses and have a role in naïve cell signaling after TCR activation. However, little is known about mROS role in TCR-independent signaling and in recall responses. Here, we found that mROS are required for IL-12 plus IL-18-driven production of IFN-γ, an essential cytokine for inflammatory and autoimmune disease development. Compared to TCR stimulation, which induced similar levels of mROS in naïve and memory-like cells, IL-12/IL-18 showed faster and augmented mROS production in memory-like cells. mROS inhibition significantly downregulated IFN-γ and CD44 expression, suggesting a direct mROS effect on memory-like T cell function. The mechanism that promotes IFN-γ production after IL-12/IL-18 challenge depended on the effect of mROS on optimal activation of downstream signaling pathways, leading to STAT4 and NF-κB activation. To relate our findings to IFN-γ-driven lupus-like disease, we used Fas-deficient memory-like CD4⁺ T cells from lpr mice. Importantly, we found significantly increased IFN-γ and mROS production in lpr compared with parental cells. Treatment of WT cells with FasL significantly reduced mROS production and the activation of signaling events leading to IFN-γ. Moreover, Fas deficiency was associated with increased mitochondrial levels of cytochrome C and caspase-3 compared with WT memory-like cells. mROS inhibition significantly reduced the population of disease-associated lpr CD44^hiCD62L^loCD4⁺ T cells and their IFN-γ production. Overall, these findings uncovered a previously unidentified role of Fas/FasL interaction in regulating mROS production by memory-like T cells. This apoptosis-independent Fas activity might contribute to the accumulation of CD44^hiCD62L^loCD4⁺ T cells that produce increased IFN-γ levels in lpr mice. Overall, our findings pinpoint mROS as central regulators of TCR-independent signaling, and support mROS pharmacological targeting to control aberrant immune responses in autoimmune-like disease.

Identification of key differential genes in intimal hyperplasia induced by left carotid artery ligation

Background

Intimal hyperplasia is a common pathological process of restenosis following angioplasty, atherosclerosis, pulmonary hypertension, vein graft stenosis, and other proliferative diseases. This study aims to screen for potential novel gene targets and mechanisms related to vascular intimal hyperplasia through an integrated microarray analysis of the Gene Expression Omnibus Database (GEO) database.

Material and Methods

The gene expression profile of the GSE56143 dataset was downloaded from the Gene Expression Omnibus database. Functional enrichment analysis, protein-protein interaction (PPI) network analysis, and the transcription factor (TF)-target gene regulatory network were used to reveal the biological functions of differential genes (DEGs). Furthermore, the expression levels of the top 10 key DEGs were verified at the mRNA and protein level in the carotid artery 7 days after ligation.

Results

A total of 373 DEGs (199 upregulated DEGs and 174 downregulated DEGs) were screened. These DEGs were significantly enriched in biological processes, including immune system process, cell adhesion, and several pathways, which were mainly associated with cell adhesion molecules and the regulation of the actin cytoskeleton. The top 10 key DEGs (Ptprc, Fn1, Tyrobp, Emr1, Itgb2, Itgax, CD44, Ctss, Ly86, and Aif1) acted as key genes in the PPI network. The verification of these key DEGs at the mRNA and protein levels was consistent with the results of the above-mentioned bioinformatics analysis.

Conclusion

The present study identified key genes and pathways involved in intimal hyperplasia induced by carotid artery ligation. These results improved our understanding of the mechanisms underlying the development of intimal hyperplasia and provided candidate targets.

Cysteine-Rich LIM-Only Protein 4 (CRP4) Promotes Atherogenesis in the ApoE-/- Mouse Model

Vascular smooth muscle cells (VSMCs) can switch from their contractile state to a synthetic phenotype resulting in high migratory and proliferative capacity and driving atherosclerotic lesion formation. The cysteine-rich LIM-only protein 4 (CRP4) reportedly modulates VSM-like transcriptional signatures, which are perturbed in VSMCs undergoing phenotypic switching. Thus, we hypothesized that CRP4 contributes to adverse VSMC behaviours and thereby to atherogenesis in vivo. The atherogenic properties of CRP4 were investigated in plaque-prone apolipoprotein E (ApoE) and CRP4 double-knockout (dKO) as well as ApoE-deficient CRP4 wildtype mice. dKO mice exhibited lower plaque numbers and lesion areas as well as a reduced content of α-smooth muscle actin positive cells in the lesion area, while lesion-associated cell proliferation was elevated in vessels lacking CRP4. Reduced plaque volumes in dKO correlated with significantly less intra-plaque oxidized low-density lipoprotein (oxLDL), presumably due to upregulation of the antioxidant factor peroxiredoxin-4 (PRDX4). This study identifies CRP4 as a novel pro-atherogenic factor that facilitates plaque oxLDL deposition and identifies the invasion of atherosclerotic lesions by VSMCs as important determinants of plaque vulnerability. Thus, targeting of VSMC CRP4 should be considered in plaque-stabilizing pharmacological strategies.

Potential of natural products in the treatment of myocardial infarction: focus on molecular mechanisms

Although conventional drugs are widely used in the prevention and treatment of cardiovascular disease (CVD), they are being used less frequently due to concerns about possible side effects over the long term. There has been a renewed research interest in medicinal plant products, and their role in protecting the cardiovascular system and treating CVD, which are now being considered as potential alternatives to modern drugs. The most important mechanism causing damage to the myocardium after heart attack and reperfusion, is increased levels of free radicals and oxidative stress. Therefore, treatment approaches often focus on reducing free radicals or enhancing antioxidant defense mechanism. It has been previously reported that bioactive natural products can protect the heart muscle in myocardial infarction (MI). Since these compounds are readily available in fruits and vegetables, they could prevent the risk of MI if they are consumed daily. Although the benefits of a healthy diet are well known, many scientific studies have focused on whether pure natural compounds can prevent and treat MI. In this review we summarize the effects of curcumin, resveratrol, quercitin, berberine, and tanshinone on MI and CVD, and focus on their proposed molecular mechanisms of action.

Salvianolic acid B ameliorates vascular endothelial dysfunction through influencing a bone morphogenetic protein 4-ROS cycle in diabetic mice

AIM

This study investigated the roles of bone morphogenetic protein-4 (BMP4) and ROS in diabetic endothelial dysfunction and explored whether Salvianolic acid B (Sal B) improved endothelial function by affecting BMP4-ROS in diabetic mice.

MAIN METHODS

db/db mice were orally administrated with Sal B (10 mg/kg/day) for one week while db/m + mice were injected with adenoviral vectors delivering BMP4 (3 × 10⁸ pfu) and then received one week-Sal B treatment. ROS levels were assayed by DHE staining. Protein expression and phosphorylation were evaluated by Western blot. Aortic rings were suspended in myograph for force measurement. Flow-mediated dilatations in the second-order mesenteric arteries were determined by pressure myograph.

KEY FINDINGS

We first revealed the existence of a BMP4-ROS cycle in db/db mice, which stimulated p38 MAPK/JNK/caspase 3 and thus participated in endothelial dysfunction. One week-treatment or 24 h-incubation with Sal B disrupted the cycle, suppressed p38 MAPK/JNK/caspase 3 cascade, and improved endothelium-dependent relaxations (EDRs) in db/db mouse aortas. Importantly, in vivo Sal B treatment also improved flow-mediated dilatation in db/db mouse second order mesenteric arteries. Furthermore, in vivo BMP4 overexpression induced oxidative stress, stimulated p38 MAPK/JNK/caspase 3, and impaired EDRs in db/m + mouse aortas, which were all reversed by Sal B.

SIGNIFICANCE

The present study demonstrates that Sal B ameliorates endothelial dysfunction through breaking the BMP4-ROS cycle and subsequently inhibiting p38 MAPK/JNK/caspase 3 in diabetic mice and provides evidence for the additional new mechanism underlying the benefit of Sal B against diabetic vasculopathy.

Adenylate Kinase 4-A Key Regulator of Proliferation and Metabolic Shift in Human Pulmonary Arterial Smooth Muscle Cells via Akt and HIF-1α Signaling Pathways

Increased proliferation of pulmonary arterial smooth muscle cells (PASMCs) in response to chronic hypoxia contributes to pulmonary vascular remodeling in pulmonary hypertension (PH). PH shares numerous similarities with cancer, including a metabolic shift towards glycolysis. In lung cancer, adenylate kinase 4 (AK4) promotes metabolic reprogramming and metastasis. Against this background, we show that AK4 regulates cell proliferation and energy metabolism of primary human PASMCs. We demonstrate that chronic hypoxia upregulates AK4 in PASMCs in a hypoxia-inducible factor-1α (HIF-1α)-dependent manner. RNA interference of AK4 decreases the viability and proliferation of PASMCs under both normoxia and chronic hypoxia. AK4 silencing in PASMCs augments mitochondrial respiration and reduces glycolytic metabolism. The observed effects are associated with reduced levels of phosphorylated protein kinase B (Akt) as well as HIF-1α, indicating the existence of an AK4-HIF-1α feedforward loop in hypoxic PASMCs. Finally, we show that AK4 levels are elevated in pulmonary vessels from patients with idiopathic pulmonary arterial hypertension (IPAH), and AK4 silencing decreases glycolytic metabolism of IPAH-PASMCs. We conclude that AK4 is a new metabolic regulator in PASMCs interacting with HIF-1α and Akt signaling pathways to drive the pro-proliferative and glycolytic phenotype of PH.

Single-cell transcriptome analysis reveals cellular heterogeneity in the ascending aortas of normal and high-fat diet-fed mice

The aorta contains numerous cell types that contribute to vascular inflammation and thus the progression of aortic diseases. However, the heterogeneity and cellular composition of the ascending aorta in the setting of a high-fat diet (HFD) have not been fully assessed. We performed single-cell RNA sequencing on ascending aortas from mice fed a normal diet and mice fed a HFD. Unsupervised cluster analysis of the transcriptional profiles from 24,001 aortic cells identified 27 clusters representing 10 cell types: endothelial cells (ECs), fibroblasts, vascular smooth muscle cells (SMCs), immune cells (B cells, T cells, macrophages, and dendritic cells), mesothelial cells, pericytes, and neural cells. After HFD intake, subpopulations of endothelial cells with lipid transport and angiogenesis capacity and extensive expression of contractile genes were defined. In the HFD group, three major SMC subpopulations showed increased expression of extracellular matrix-degradation genes, and a synthetic SMC subcluster was proportionally increased. This increase was accompanied by upregulation of proinflammatory genes. Under HFD conditions, aortic-resident macrophage numbers were increased, and blood-derived macrophages showed the strongest expression of proinflammatory cytokines. Our study elucidates the nature and range of the cellular composition of the ascending aorta and increases understanding of the development and progression of aortic inflammatory disease.

Cardiovascular Effects Mediated by HMMR and CD44

Cardiovascular disease (CVD) is the leading cause of death worldwide. The most dangerous life-threatening symptoms of CVD are myocardial infarction and stroke. The causes of CVD are not entirely clear, and new therapeutic targets are still being sought. One of the factors involved in CVD development among vascular damage and oxidative stress is chronic inflammation. It is known that hyaluronic acid plays an important role in inflammation and is regulated by numerous stimuli, including proinflammatory cytokines. The main receptors for hyaluronic acid are CD44 and RHAMM. These receptors are membrane proteins that differ in structure, but it seems that they can perform similar or synergistic functions in many diseases. Both RHAMM and CD44 are involved in cell migration and wound healing. However, their close association with CVD is not fully understood. In this review, we describe the role of both receptors in CVD.

Identification of retinoid acid induced 16 as a novel androgen receptor target in prostate cancer cells

BACKGROUND

Retinoid acid induced 16 (RAI16) was reported to enhance tumorigenesis in hepatocellular carcinoma (HCC). The androgen receptor (AR) is a nuclear hormone receptor that functions as a critical oncogene in several cancer progressions. However, whether RAI16 is a candidate AR target gene that may involve in prostate cancer progression was unclear.

MATERIALS & METHODS

RAI16 expression was detected in prostate cancer cells with or without the AR agonist R1881 treatment by quantitative RT-PCR and Western blot. Direct AR binding to the RAI16 promoter was tested using AR chromatin immunoprecipitation (ChIP) and luciferase assay. Cell viability and colony formation assays in response to R1881 were analyzed in cells with RAI16 knockdown by specific siRNA.

RESULTS

The expression of RAI16 was high in LNCaP(AI), LNCaP(AD), C4-2 expressing AR, but low in Du145 and Pc-3 cells without AR expressing. In addition, the expression of RAI16 could be induced by 10 nM R1881 treatment LNCaP(AD) and C4-2 cells, but inhibited by AR specific siRNA treatment. Furthermore, AR binds directly to ARE3 (-2003~-1982bp) of RAI16 promoter region by ChIP and luciferase assay. RAI16 knockdown inhibited the enhancement of cell viability and colony formation of AR stimulation.

CONCLUSIONS

We demonstrate for the first time that RAI16 is a direct target gene of AR. RAI16 may involved in cell growth of prostate cancer cells in response to AR signaling.

Protein Kinase Cθ Via Activating Transcription Factor 2-Mediated CD36 Expression and Foam Cell Formation of Ly6Chi Cells Contributes to Atherosclerosis

BACKGROUND

Although the role of thrombin in atherothrombosis is well studied, its role in the pathogenesis of diet-induced atherosclerosis is not known.

METHODS

Using a mouse model of diet-induced atherosclerosis and molecular biological approaches, here we have explored the role of thrombin and its G protein-coupled receptor signaling in diet-induced atherosclerosis.

RESULTS

In exploring the role of G protein-coupled receptor signaling in atherogenesis, we found that thrombin triggers foam cell formation via inducing CD36 expression, and these events require Par1-mediated Gα12-Pyk2-Gab1-protein kinase C (PKC)θ-dependent ATF2 activation. Genetic deletion of PKCθ in apolipoprotein E (ApoE)^-/- mice reduced Western diet-induced plaque formation. Furthermore, thrombin induced Pyk2, Gab1, PKCθ, and ATF2 phosphorylation, CD36 expression, and foam cell formation in peritoneal macrophages of ApoE^-/- mice. In contrast, thrombin only stimulated Pyk2 and Gab1 but not ATF2 phosphorylation or its target gene CD36 expression in the peritoneal macrophages of ApoE^-/-:PKCθ^-/- mice, and it had no effect on foam cell formation. In addition, the aortic root cross-sections of Western diet-fed ApoE^-/- mice showed increased Pyk2, Gab1, PKCθ, and ATF2 phosphorylation and CD36 expression as compared with ApoE^-/-:PKCθ^-/- mice. Furthermore, although the monocytes from peripheral blood and the aorta of Western diet-fed ApoE^-/- mice were found to contain more of Ly6C^hi cells than Ly6C^lo cells, the monocytes from Western diet-fed ApoE^-/-:PKCθ^-/- mice were found to contain more Ly6C^lo cells than Ly6C^hi cells. It is interesting to note that the Ly6C^hi cells showed higher CD36 expression with enhanced capacity to form foam cells as compared with Ly6C^lo cells.

CONCLUSIONS

These findings reveal for the first time that thrombin-mediated Par1-Gα12 signaling via targeting Pyk2-Gab1-PKCθ-ATF2-dependent CD36 expression might be playing a crucial role in diet-induced atherogenesis.

Rac3, but not Rac1, promotes ox-LDL induced endothelial dysfunction by downregulating autophagy

The endothelial dysfunction induced by oxidized low-density lipoprotein (ox-LDL) plays an important role in the pathogenesis of atherosclerosis, which can lead to oxidative stress and inflammation. The role of autophagy in the process of atherosclerosis has drawn increasing attention. The human umbilical vein endothelial cells (HUVECs), whose Ras-related C3 botulinum toxin substrate 1 (Rac1) and Rac3 was knockdown, were used to detect whether the possible molecular mechanisms of Rac1 and Rac3 for anti-inflammatory in endothelial cells was effected by downregulation of autophagy. The HUVECs were incubated with ox-LDL. The inflammatory factors and autophagy proteins were evaluated to ascertain and compare the effect of Rac1 and Rac3 on autophagy. Then, 3-methyladenine (3-MA) as an inhibiter of autophagy was used to detect whether the effect of Rac1 and Rac3 was related to autophagy. ox-LDL-induced cell dysfunction in HUVECs was determined by testing the formation of foam cells, the expression of nuclear factor (NF)-κB and nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 and NF-κB p65 and other inflammatory factors, the release of reactive oxygen species by oxidative stress and the dysfunction of the cytomembrane. And ApoE^-/- mice on a high-fat diet were used as an animal model to detect the effect of Rac1 and Rac3 in vivo. The results showed that when Rac1 and Rac3 were decreased in HUVECs, the cell dysfunction caused by ox-LDL was inhibited. If 3-MA was used to inhibit autophagy in Rac1 and Rac3 knockdown cells, the injury induced by ox-LDL on the cells was recovered. These results indicated that the effect of Rac1 and Rac3 was combined with ox-LDL, which was related to inhibition of autophagy. The effect of Rac3 was more significant than that of Rac1.

Adenylate kinase 4 modulates oxidative stress and stabilizes HIF-1α to drive lung adenocarcinoma metastasis

Background

Adenylate kinase 4 (AK4) has been identified as a biomarker of metastasis in lung cancer. However, the impacts of AK4 on metabolic genes and its translational value for drug repositioning remain unclear.

Methods

Ingenuity upstream analyses were used to identify potential transcription factors that regulate the AK4 metabolic gene signature. The expression of AK4 and its upstream regulators in lung cancer patients was examined via immunohistochemistry. Pharmacological and gene knockdown/overexpression approaches were used to investigate the interplay between AK4 and its upstream regulators during epithelial-to-mesenchymal transition (EMT). Drug candidates that reversed AK4-induced gene expression were identified by querying a connectivity map. Orthotopic xenograft mouse models were established to evaluate the therapeutic efficacy of drug candidates for metastatic lung cancer.

Results

We found that HIF-1α is activated in the AK4 metabolic gene signature. IHC analysis confirmed this positive correlation, and the combination of both predicts worse survival in lung cancer patients. Overexpression of AK4 exaggerates HIF-1α protein expression by increasing intracellular ROS levels and subsequently induces EMT under hypoxia. Attenuation of ROS production with N-acetylcysteine abolishes AK4-induced invasion potential under hypoxia. Pharmacogenomics analysis of the AK4 gene signature revealed that withaferin-A could suppress the AK4-HIF-1α signaling axis and serve as a potent anti-metastatic agent in lung cancer.

Conclusions

Overexpression of AK4 promotes lung cancer metastasis by enhancing HIF-1α stability and EMT under hypoxia. Reversing the AK4 gene signature with withaferin-A may serve as a novel therapeutic strategy to treat metastatic lung cancer.

Electronic supplementary material

The online version of this article (10.1186/s13045-019-0698-5) contains supplementary material, which is available to authorized users.

NOXA1-dependent NADPH oxidase regulates redox signaling and phenotype of vascular smooth muscle cell during atherogenesis

Increased reactive oxygen species (ROS) production and inflammation are key factors in the pathogenesis of atherosclerosis. We previously reported that NOX activator 1 (NOXA1) is the critical functional homolog of p67phox for NADPH oxidase activation in mouse vascular smooth muscle cells (VSMC). Here we investigated the effects of systemic and SMC-specific deletion of Noxa1 on VSMC phenotype during atherogenesis in mice.

Neointimal hyperplasia following endovascular injury was lower in Noxa1-deficient mice versus the wild-type following endovascular injury. Noxa1 deletion in Apoe^-/- or Ldlr^-/- mice fed a Western diet showed 50% reduction in vascular ROS and 30% reduction in aortic atherosclerotic lesion area and aortic sinus lesion volume (P < 0.01). SMC-specific deletion of Noxa1 in Apoe^-/- mice (Noxa1^SMC-/-/Apoe^-/-) similarly decreased vascular ROS levels and atherosclerotic lesion size. TNFα-induced ROS generation, proliferation and migration were significantly attenuated in Noxa1-deficient versus wild-type VSMC. Immunofluorescence analysis of atherosclerotic lesions showed a significant decrease in cells positive for CD68 and myosin11 (22% versus 9%) and Mac3 and α-actin (17% versus 5%) in the Noxa1^SMC-/-/Apoe^-/- versus Apoe^-/- mice. The expression of transcription factor KLF4, a modulator of VSMC phenotype, and its downstream targets – VCAM1, CCL2, and MMP2 – were significantly reduced in the lesions of Noxa1^SMC-/-/Apoe^-/- versus Apoe^-/- mice as well as in oxidized phospholipids treated Noxa1^SMC-/- versus wild-type VSMC.

Our data support an important role for NOXA1-dependent NADPH oxidase activity in VSMC plasticity during restenosis and atherosclerosis, augmenting VSMC proliferation and migration and KLF4-mediated transition to macrophage-like cells, plaque inflammation, and expansion.

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NOXA1 is a VSMC-specific regulator of NADPH oxidase 1 activity and downstream cell signaling.

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NOX1 NADPH oxidase-dependent ROS generation is required for VSMC proliferation and migration after endovascular injury.

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NOXA1-dependent NOX1 activation of KLF4 in atherosclerotic lesions induces SMC phenotypic switch to macrophage-like cells.

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Atherosclerotic lesion macrophage-like cells promote plaque inflammation, matrix remodeling and increase volume expansion.

Genetic Alterations in Oxidant and Anti-Oxidant Enzymes in the Vascular System

Cardiovascular diseases (CVD) are one of the prime causes of mortality worldwide. Experimental animal models have become a valuable tool to investigate and further advance our knowledge on etiology, pathophysiology and intervention. They also provide a great opportunity to understand the contribution of different genes and effector molecules in the pathogenesis and development of diseases at the sub-cellular levels. High levels of reactive oxygen species (ROS) have been associated with the progression of CVD such as ischemic heart disease (IHD), myocardial infarction, hypertension, atherosclerosis, aortic aneurysm, aortic dissection and others. On the contrary, low levels of antioxidants were associated with exacerbated cardiovascular event. Major focus of this review is on vascular pathogenesis that leads to CVD, with special emphasis on the roles of oxidant/antioxidant enzymes in health and disease progression in vascular cells including vascular endothelium. The major oxidant enzymes that have been implicated with the progression of CVD include NADPH Oxidase, nitric oxide synthase, monoamine oxidase, and xanthine oxidoreductase. The major antioxidant enzymes that have been attributed to normalizing the levels of oxidative stress include superoxide dismutases, catalase and glutathione peroxidases (GPx), and thioredoxin. Cardiovascular phenotypes of major oxidants and antioxidants knockout and transgenic animal models are discussed here.

The CD44-HA axis and inflammation in atherosclerosis: A temporal perspective

Cardiovascular disease (CVD) due to atherosclerosis is a disease of chronic inflammation at both the systemic and the tissue level. CD44 has previously been implicated in atherosclerosis in both humans and mice. This multi-faceted receptor plays a critical part in the inflammatory response during the onset of CVD, though little is known of CD44's role during the latter stages of the disease. This review focuses on the role of CD44-dependent HA-dependent effects on inflammatory cells in several key processes, from disease initiation throughout the progression of atherosclerosis. Understanding how CD44 and HA regulate inflammation in atherogenesis is key in determining the utility of the CD44-HA axis as a therapeutic target to halt disease and potentially promote disease regression.

Transforming growth factor β1 (TGFβ1)-induced CD44V6-NOX4 signaling in pathogenesis of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive clinical syndrome of fatal outcome. The lack of information about the signaling pathways that sustain fibrosis and the myofibroblast phenotype has prevented the development of targeted therapies for IPF. Our previous study showed that isolated fibrogenic lung fibroblasts have high endogenous levels of the hyaluronan receptor, CD44V6 (CD44 variant containing exon 6), which enhances the TGFβ1 autocrine signaling and induces fibroblasts to transdifferentiate into myofibroblasts. NADPH oxidase 4 (NOX4) enzyme, which catalyzes the reduction of O₂ to hydrogen peroxide (H₂O₂), has been implicated in the cardiac and lung myofibroblast phenotype. However, whether CD44V6 regulates NOX4 to mediate tissue repair and fibrogenesis is not well-defined. The present study assessed the mechanism of how TGF-β-1-induced CD44V6 regulates the NOX4/reactive oxygen species (ROS) signaling that mediates the myofibroblast differentiation. Specifically, we found that NOX4/ROS regulates hyaluronan synthesis and the transcription of CD44V6 via an effect upon AP-1 activity. Further, CD44V6 is part of a positive-feedback loop with TGFβ1/TGFβRI signaling that acts to increase NOX4/ROS production, which is required for myofibroblast differentiation, myofibroblast differentiation, myofibroblast extracellular matrix production, myofibroblast invasion, and myofibroblast contractility. Both NOX4 and CD44v6 are up-regulated in the lungs of mice subjected to experimental lung injury and in cases of human IPF. Genetic (CD44v6 shRNA) or a small molecule inhibitor (CD44v6 peptide) targeting of CD44v6 abrogates fibrogenesis in murine models of lung injury. These studies support a function for CD44V6 in lung fibrosis and offer proof of concept for therapeutic targeting of CD44V6 in lung fibrosis disorders.

Resveratrol-Mediated Expression of KLF15 in the Ischemic Myocardium is Associated with an Improved Cardiac Phenotype

PURPOSE

Myocardial infarction results in physiological derangements that lead to structural and functional alterations to the myocardium. In addition, oxidative stress potentiates cardiac remodeling and drives disease progression. Unfortunately, treatment with antioxidants in clinical trials have failed to show any therapeutic benefits despite the positive results reported in animal studies, which warrants further investigation into their mechanism(s) of action. Accordingly, the aim of this study was to elucidate a previously unknown mechanism of action for the antioxidant, resveratrol, in the treatment of the ischemic heart.

METHODS

Male Sprague-Dawley rats underwent four weeks of chronic myocardial ischemia with or without daily resveratrol treatment (10 mg/kg/day). The expression and signaling of Krüppel-like factor 15 (KLF15) were determined by immunoblot and qPCR analyses, respectively.

RESULTS

Chronic myocardial ischemia reduced the protein expression of KLF15. In parallel, mRNA transcripts of KLF15 gene targets actively involved in cardiac remodeling were robustly increased in untreated hearts. Importantly, daily treatment with resveratrol stimulated KLF15 expression, which was associated with attenuated gene expression and an improved cardiac phenotype. Additionally, we describe a novel role for KLF15 in the regulation of redox homeostasis.

CONCLUSION

Based on our current findings, it appears that resveratrol treatment induces KLF15 expression, which may, in part, explain its therapeutic efficacy to improve the cardiac phenotype following ischemic injury.

NOX4 NADPH Oxidase-Dependent Mitochondrial Oxidative Stress in Aging-Associated Cardiovascular Disease

AIMS

Increased oxidative stress and vascular inflammation are implicated in increased cardiovascular disease (CVD) incidence with age. We and others demonstrated that NOX1/2 NADPH oxidase inhibition, by genetic deletion of p47phox, in Apoe(-/-) mice decreases vascular reactive oxygen species (ROS) generation and atherosclerosis in young age. The present study examined whether NOX1/2 NADPH oxidases are also pivotal to aging-associated CVD.

RESULTS

Both aged (16 months) Apoe(-/-) and Apoe(-/-)/p47phox(-/-) mice had increased atherosclerotic lesion area, aortic stiffness, and systolic dysfunction compared with young (4 months) cohorts. Cellular and mitochondrial ROS (mtROS) levels were significantly higher in aortic wall and vascular smooth muscle cells (VSMCs) from aged wild-type and p47phox(-/-) mice. VSMCs from aged mice had increased mitochondrial protein oxidation and dysfunction and increased vascular cell adhesion molecule 1 expression, which was abrogated with (2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl)triphenylphosphonium chloride (MitoTEMPO) treatment. NOX4 expression was increased in the vasculature and mitochondria of aged mice and its suppression with shRNA in VSMCs from aged mice decreased mtROS levels and improved function. Increased mtROS levels were associated with enhanced mitochondrial NOX4 expression in aortic VSMCs from aged subjects, and NOX4 expression levels in arterial wall correlated with age and atherosclerotic severity. Aged Apoe(-/-) mice treated with MitoTEMPO and 2-(2-chlorophenyl)-4-methyl-5-(pyridin-2-ylmethyl)-1H-pyrazolo[4,3-c]pyridine-3,6(2H,5H)-dione had decreased vascular ROS levels and atherosclerosis and preserved vascular and cardiac function.

INNOVATION AND CONCLUSION

These data suggest that NOX4, but not NOX1/2, and mitochondrial oxidative stress are mediators of CVD in aging under hyperlipidemic conditions. Regulating NOX4 activity/expression and using mitochondrial antioxidants are potential approaches to reducing aging-associated CVD.

Vascular smooth muscle cell in atherosclerosis

Vascular smooth muscle cells (VSMCs) exhibit phenotypic and functional plasticity in order to respond to vascular injury. In case of the vessel damage, VSMCs are able to switch from the quiescent 'contractile' phenotype to the 'proinflammatory' phenotype. This change is accompanied by decrease in expression of smooth muscle (SM)-specific markers responsible for SM contraction and production of proinflammatory mediators that modulate induction of proliferation and chemotaxis. Indeed, activated VSMCs could efficiently proliferate and migrate contributing to the vascular wall repair. However, in chronic inflammation that occurs in atherosclerosis, arterial VSMCs become aberrantly regulated and this leads to increased VSMC dedifferentiation and extracellular matrix formation in plaque areas. Proatherosclerotic switch in VSMC phenotype is a complex and multistep mechanism that may be induced by a variety of proinflammatory stimuli and hemodynamic alterations. Disturbances in hemodynamic forces could initiate the proinflammatory switch in VSMC phenotype even in pre-clinical stages of atherosclerosis. Proinflammatory signals play a crucial role in further dedifferentiation of VSMCs in affected vessels and propagation of pathological vascular remodelling.

Oxidative stress, NADPH oxidases, and arteries

Atherosclerosis and its major complications - myocardial infarction and stroke - remain major causes of death and disability in the United States and world-wide. Indeed, with dramatic increases in obesity and diabetes mellitus, the prevalence and public health impact of cardiovascular diseases (CVD) will likely remain high. Major advances have been made in development of new therapies to reduce the incidence of atherosclerosis and CVD, in particular for treatment of hypercholesterolemia and hypertension. Oxidative stress is the common mechanistic link for many CVD risk factors. However, only recently have the tools existed to study the interface between oxidative stress and CVD in animal models. The most important source of reactive oxygen species (and hence oxidative stress) in vascular cells are the multiple forms of enzymes nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase). Recently published and emerging studies now clearly establish that: 1) NADPH oxidases are of critical importance in atherosclerosis and hypertension in animal models; 2) given the tissue-specific expression of key components of NADPH oxidase, it may be possible to target vascular oxidative stress for prevention of CVD.

Id proteins in the vasculature: from molecular biology to cardiopulmonary medicine

The inhibitors of differentiation (Id) proteins belong to the helix-loop-helix group of transcription factors and regulate cell differentiation and proliferation. Recent studies have reported that Id proteins play important roles in cardiogenesis and formation of the vasculature. We have also demonstrated that heritable pulmonary arterial hypertension (HPAH) patients have dysregulated Id gene expression in pulmonary artery smooth muscle cells. The interaction between bone morphogenetic proteins and other growth factors or cytokines regulates Id gene expression, which impacts on pulmonary vascular cell differentiation and proliferation. Exploration of the roles of Id proteins in vascular remodelling that occurs in PAH and atherosclerosis might provide new insights into the molecular basis of these diseases. In addition, current progress in identification of the interactors of Id proteins will further the understanding of the function of Ids in vascular cells and enable the identification of novel targets for therapy in PAH and other cardiovascular diseases.

BMP4 is increased in the aortas of diabetic ApoE knockout mice and enhances uptake of oxidized low density lipoprotein into peritoneal macrophages

Background

BMP4, a member of the transforming growth factor-beta superfamily, is upregulated in the aortas of diabetic db/db mice. However, little is known about its role in diabetic atherosclerosis. Therefore, we examined the roles of BMP4 in the formation of diabetic atherosclerosis in apolipoprotein E knockout (ApoE KO) mice and in the uptake of oxidized low density lipoprotein (oxLDL) in peritoneal macrophages of wild-type mice.

Methods

To induce diabetes, ApoE KO mice were intraperitoneally injected with streptozotocin. Diabetic and non-diabetic ApoE KO mice were then fed a high-fat diet for 4 weeks. Next, to investigate a role of BMP4 in the peritoneal macrophages, we examined the uptake of oxLDL in BMP4-treated macrophages.

Results

Diabetic ApoE KO mice showed accelerated progression of aortic plaques accompanied by increased luminal plaque area. Western blot analysis showed that BMP4 expression in the whole aorta was greatly increased in diabetic ApoE KO mice, than non-diabetic mice. Western blot analysis showed that the BMP4/SMAD1/5/8 signaling pathway was strongly activated in the aorta from diabetic ApoE KO mice, compared with control ApoE KO mice. Double immunofluorescence staining showed that BMP4 was expressed in MOMA2-labeled macrophage in the aortic lesions of ApoE KO mice. BMP4 significantly increased the uptake of oxLDL into peritoneal macrophages in vitro.

Conclusion

We show that in the aorta of diabetic ApoE KO mice, BMP4 is increased and activates SMAD1/5/8. Our in vitro findings indicate that BMP4 enhances oxLDL uptake in mouse peritoneal macrophages, suggesting BMP4 may be involved in aortic plaque formation in diabetic ApoE KO mice. Targeting BMP4 may offer a new strategy for inhibition of plaque progression and stabilization of atherosclerotic lesions.

Endothelial dysfunction in diabetes and hypertension: cross talk in RAS, BMP4, and ROS-dependent COX-2-derived prostanoids

Vascular endothelium regulates cardiovascular function, and endothelial dysfunction is the key initiator for arteriosclerosis and thrombosis and their complications. The endothelium is a dynamic interface that responds to various stimuli and synthesizes and liberates vasoactive molecules such as nitric oxide, prostaglandins, hyperpolarizing factor, and endothelin. Risk factors such as hypertension, hypercholesterolemia, smoking, and hyperglycemia impair the ability of the endothelium to respond to physical or chemical stimulation appropriately, and increased oxidative stress is believed to be a major culprit. This brief article reviews the interplay among several oxidative stress regulators in the vascular wall and highlights therapeutic relevance through deeper understanding of the interplay between the renin-angiotensin system, nicotinamide adenine dinucleotide phosphate, reduced oxidase, bone morphogenic protein 4, and cyclooxygenase 2-derived prostaglandins as a concerted pathogenic cascade in inducing and maintaining endothelial dysfunction in hypertension and diabetes.

Redox signaling in cardiovascular health and disease

Spatiotemporal regulation of the activity of a vast array of intracellular proteins and signaling pathways by reactive oxygen species (ROS) governs normal cardiovascular function. However, data from experimental and animal studies strongly support that dysregulated redox signaling, resulting from hyperactivation of various cellular oxidases or mitochondrial dysfunction, is integral to the pathogenesis and progression of cardiovascular disease (CVD). In this review, we address how redox signaling modulates the protein function, the various sources of increased oxidative stress in CVD, and the labyrinth of redox-sensitive molecular mechanisms involved in the development of atherosclerosis, hypertension, cardiac hypertrophy and heart failure, and ischemia-reperfusion injury. Advances in redox biology and pharmacology for inhibiting ROS production in specific cell types and subcellular organelles combined with the development of nanotechnology-based new in vivo imaging systems and targeted drug delivery mechanisms may enable fine-tuning of redox signaling for the treatment and prevention of CVD.

Bone morphogenic protein-4 contributes to venous endothelial dysfunction in patients with diabetes undergoing coronary revascularization

BACKGROUND

Hyperglycemia-induced venous endothelial dysfunction accelerates the progression of vein graft failure in patients with diabetes undergoing surgical coronary revascularization. Recent studies suggest the importance of bone morphogenic protein-4 (BMP4)-induced arterial endothelial dysfunction in the development of hypertension and atherosclerosis. The present study investigated the potential role of BMP4 in the pathogenesis of venous endothelial dysfunction in the setting of diabetes.

METHODS

Segments of saphenous vein from pigs and from patients with diabetes or patients without diabetes, as well as human umbilical venous endothelial cells (HUVECs), were used. The changes of BMP4 expression in veins from patients and in HUVECs cultured under hyperglycemic conditions were evaluated by Western blot assay. The effects of BMP4 on the production of reactive oxygen species (ROS) and endothelium-dependent venous relaxation were assessed by using dihydroethidium fluorescence and isometric tension measurements, respectively.

RESULTS

The impaired venous endothelium-dependent relaxations (2.9%±4.8% versus control group 74.1%±10%; p<0.01) accompanied by markedly increased BMP4 expression were observed in the diabetic group. The level of BMP4 expression in HUVECs treated with high levels of glucose were elevated in a glucose concentration-dependent manner. Ex vivo treatment with the BMP4 antagonist noggin significantly improved endothelium-dependent relaxations and inhibited accumulation of ROS in saphenous veins from patients with diabetes. Noggin treatment had no effect on the venous endothelium-dependent relaxations in individuals without diabetes. Meanwhile, BMP4 inhibited acetylcholine-induced relaxation (control group, 90%±7.1% versus BMP4-treated group, 52%±12.6%; p<0.05) and enhanced ROS production in porcine saphenous veins. Such harmful effects were again reversed by noggin.

CONCLUSIONS

The increased BMP4 expression and related ROS overproduction may play an important role in the development of hyperglycemia-induced venous endothelial dysfunction.

Ginkgo biloba extract attenuates oxLDL-induced endothelial dysfunction via an AMPK-dependent mechanism

Atherosclerosis is a complex inflammatory arterial disease, and oxidized low-density lipoprotein (oxLDL) is directly associated with chronic vascular inflammation. Previous studies have shown that Ginkgo biloba extract (GbE) acts as a therapeutic agent for neurological and cardiovascular disorders. However, the mechanisms mediating the actions of GbE are still largely unknown. In the present study, we tested the hypothesis that GbE protects against oxLDL-induced endothelial dysfunction via an AMP-activated protein kinase (AMPK)-dependent mechanism. Human umbilical vein endothelial cells were treated with GbE, followed by oxLDL, for indicated time periods. Results from Western blot showed that GbE inhibited the membrane translocation of the NADPH oxidase subunits p47(phox) and Rac-1 and attenuated the increase in protein expression of membrane subunits gp91 and p22(phox) caused by oxLDL-induced AMPK dephosphorylation and subsequent PKC activation. AMPK-α(1)-specific small interfering RNA-transfected cells that had been exposed to GbE followed by oxLDL revealed elevated levels of PKC and p47(phox). In addition, exposure to oxLDL resulted in reduced AMPK-mediated Akt/endothelial nitric oxide (NO) synthase signaling and the induction of phosphorylation of p38 mitogen-activated protein kinase, which, in turn, activated NF-κB-mediated inflammatory responses, such as the release of interleukin-8, the expression of the adhesion molecule, and the adherence of monocytic cells to human umbilical vein endothelial cells. Furthermore, oxLDL upregulated the expression of inducible NO synthase, thereby augmenting the formation of NO and protein nitrosylation. Pretreatment with GbE, however, exerted significant cytoprotective effects in a dose-dependent manner. Results from this study may provide insight into a possible molecular mechanism by which GbE protects against oxLDL-induced endothelial dysfunction.

Retinoic acid induced 16 enhances tumorigenesis and serves as a novel tumor marker for hepatocellular carcinoma

Our previous work identified downregulated miR-483-5p in hepatocellular carcinoma (HCC). This study aims to identify the target of miR-483-5p, evaluate the potential value of this target as a tumor marker for HCC and explore the role of this target in HCC tumorigenesis. Upregulated retinoic acid induced 16 (RAI16) (17/18 cases) was negatively correlated with downregulated miR-483-5p (14/18 cases) in HCC tissues. The dual-luciferase reporter assay showed that RAI16 is a target of miR-483-5p. Immunohistochemistry analysis showed RAI16 was moderate or strong staining in tumor tissues but negative or weak staining in adjacent non-tumor tissues. The sensitivity and specificity of RAI16 for HCC diagnosis were 70.6 and 93.6%, respectively, and increased to 80.9 and 92.0% when combined with glypican-3. Finally, overexpression or knockdown of RAI16 increased or decreased cell viability and colony formation in HCC cell lines and enhanced or inhibited tumor cell growth in xenograft nude mice. Mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) and transforming growth factor-β pathways were mostly affected by RAI16. RAI16 could activate the phosphorylation of ERK1/2 and SMAD2/3. In conclusion, RAI16 may serve as a useful therapeutic agent for HCC gene therapy and tumor marker for HCC diagnosis.

Transcriptional regulation of platelet-derived growth factor-B chain by thrombin in endothelial cells: involvement of Egr-1 and CREB-binding protein

Thrombin and platelet-derived growth factor-B chain (PDGF-B) are key factors in the stimulation of atherosclerosis. The effect of thrombin on PDGF-B production has been characterized. However, the underlying mechanism is still far clear. Here, we investigate the transcription factors and regulators that are involved in PDGF-B production caused by thrombin in endothelial cells (ECs). Levels of PDGF were analyzed by real-time RT-PCR and ELISA, while levels of early growth response-1 (Egr-1) were analyzed by real-time RT-PCR and western blot. To evaluate the function of CBP and Egr-1 involved in regulation of PDGF-B, small interfering RNA (siRNA) were used to down-regulate their expression in mRNA and protein level. Interaction of Egr-1 and CBP was measured with immunoprecipitation and western blot. Thrombin induced an early and transient up-regulation of transcription factor early Egr-1, which was followed by a delayed increase of PDGF-B. siRNA against Egr-1-inhibited thrombin-induced PDGF-B production. Furthermore, thrombin could enhance the interaction of Egr-1 with its co-activator CREB-binding protein (CBP). CBP knockdown attenuated this interaction, and led to a reduction of PDGF-B expression induced by thrombin. Our results suggest that CBP might be one of the main interaction targets for Egr-1, and the transient activation of Egr-1 and recruitment of CBP are required for thrombin-induced PDGF-B in ECs.

Xuezhikang, extract of red yeast rice, inhibited tissue factor and hypercoagulable state through suppressing nicotinamide adenine dinucleotide phosphate oxidase and extracellular signal-regulated kinase activation

Xuezhikang, extract of red yeast rice, is a traditional Chinese medicine with multiple cardioprotective effect. It contains a family of naturally occurring statins, such as lovastatin. Tissue factor (TF) is overexpressed in macrophages of lipid core plaques, which display high procoagulant activity and seem to be a potentially target for anti-atherothrombosis. Therefore, the purpose of this study was to explore the effect and possible molecular mechanisms of xuezhikang on inhibiting TF expression and hypercoagulable state and the differences compared with lovastatin. Our results showed that xuezhikang significantly suppressed oxidized low-density lipoprotein-induced TF expression in macrophages in a concentration-dependent manner. Xuezhikang reduced nicotinamide adenine dinucleotide phosphate oxidase activity by decreasing membrane translocation of p47 through inhibition of extracellular signal-regulated kinase 1/2 activation. Nicotinamide adenine dinucleotide phosphate inhibitor (diphenyleneiodonium) also inhibited the oxidized low-density lipoprotein-induced TF expression, similar to the effects of xuezhikang. Furthermore, consistent with the severity of aortic atherosclerosis, xuezhikang (300 mg·kg·d) significantly reduced blood coagulation activation and TF expression in high-cholesterol diet-induced atherosclerotic rats. In addition, xuezhikang was more potent than lovastatin on inhibiting the expression of TF and nicotinamide adenine dinucleotide phosphate oxidase activation. These observations provide evidences that inhibition of xuezhikang on hypercoagulation and TF expression may partly account for its cardioprotective benefits.

miRNAs: roles and clinical applications in vascular disease

miRNAs are small, endogenously expressed noncoding RNAs that regulate gene expression, mainly at the post-transcriptional level, via degradation or translational inhibition of their target mRNAs. Functionally, an individual miRNA can regulate the expression of multiple target genes. The study of miRNAs is rapidly growing and recent studies have revealed a significant role of miRNAs in vascular biology and disease. Many miRNAs are highly expressed in the vasculature, and their expression is dysregulated in diseased vessels. Several miRNAs have been found to be critical modulators of vascular pathologies, such as atherosclerosis, lipoprotein metabolism, inflammation, arterial remodeling, angiogenesis, smooth muscle cell regeneration, hypertension, apoptosis, neointimal hyperplasia and signal transduction pathways. Thus, miRNAs may serve as novel biomarkers and/or therapeutic targets for vascular disease. This article summarizes the current studies related to the disease correlations and functional roles of miRNAs in the vascular system and discusses the potential applications of miRNAs in vascular disease.

Role for Nox1 NADPH oxidase in atherosclerosis

OBJECTIVE

Examine the contribution of Nox1 NADPH oxidase to atherogenesis.

METHODS AND RESULTS

Male apolipoprotein E deficient mice (ApoE(-/-)) and male mice deficient in both apolipoprotein E and Nox1 (ApoE(-/-) Nox1(-/y)) received an atherogenic diet for 18 weeks. Mean blood pressures, body weights, and serum cholesterol levels were similar between the two groups of mice. Deficiency of Nox1 decreased superoxide levels and reduced lesion area in the aortic arch from 43% (ApoE(-/-)) to 28% (ApoE(-/-) Nox1(-/y)). The reduction in lesion size at the level of the aortic valve in ApoE(-/-)/Nox1(-/y) was accompanied by a decrease in macrophage infiltration as compared to ApoE(-/-) mice. Carotid artery ligation in ApoE(-/-) mice induced accelerated intimal hyperplasia with decreased cellular proliferation and increased collagen content in the neointima of vessels deficient in Nox1.

CONCLUSIONS

Nox1-derived ROS modify lesion composition and contribute to lesion size in a murine model of atherosclerosis.

Id1: a novel therapeutic target for patients with atherosclerotic plaque rupture

Plaque neovascularization and inflammation are responsible for plaque destabilization and rupture. However, the precise triggers for inflammation and neovascularization in atherosclerosis are largely unknown. Id1 (inhibitor of DNA-binding) protein is a helix-loop-helix transcription factor and plays an important role in angiogenesis and inflammation. The expression of Id1 can be up-regulated by plaque formation factors such as vascular endothelial growth factor (VEGF), hypoxia, NAD(P)H oxidase, and TNF-alpha. Moreover, Id1 is critical to endothelial progenitor cell (EPC) population formation and angiogenesis. Evidence from diverse sources has suggested that Id1 may affect plaque destabilization through angiogenesis and inflammation. Herein we hypothesize that Id1 is an important protein for the development and progression of atherosclerotic plaque destabilization and hence blocking the expression of Id1 may serve as new targets for antiatherogenic therapy.

Low molecular weight (LMW) heparin inhibits injury-induced femoral artery remodeling in mouse via upregulating CD44 expression

OBJECTIVE

The mechanism of postangioplasty restenosis remains poorly understood. Low molecular weight (LMW) heparin has been shown to inhibit the proliferation of vascular smooth muscle cells (VSMCs), which is the principal characteristic of restenosis. Studies have shown that LMW heparin could bind to CD44. We hypothesized that LMW heparin might modulate CD44 expression thereby decreasing vascular remodeling.

METHODS

Vascular remodeling was induced in CD44(+/+) and CD44(-/-) mice and treated with LMW heparin. The arteries were harvested for histologic assessment and determination of CD44 expression. Bone marrow transplantation was introduced to further explore the role and functional sites of CD44. Effects of LMW heparin on growth capacity, CD44 expression were further studied using the cultured mouse VSMCs.

RESULTS

Transluminal injury induced remarkable remodeling in mouse femoral artery (sham wall thickness percentage [WT%]: 3.4 ± 1.2% vs injury WT%: 31.8 ± 4.7%; P < .001). LMW heparin reduced the remodeling significantly (WT%: 17.8 ± 3.5%, P < .005). CD44(-/-) mice demonstrated considerably thicker arterial wall remodeling (WT%: 46.2 ± 7.6%, P = .0035), and CD44-chimeric mice exhibited equal contributions of the local and circulating CD44 signal to the neointima formation. LMW heparin markedly upregulated CD44 expression in the injured femoral arteries. In vitro, LMW heparin decreased mouse VSMC growth capacity and upregulated its CD44 expression simultaneously in a dose-dependent and time-dependent manner, which could be partially blocked by CD44 inhibitor.

CONCLUSIONS

LMW heparin inhibits injury-induced femoral artery remodeling, at least partially, by upregulating CD44 expression.

Bone Morphogenic Protein-4 Impairs Endothelial Function Through Oxidative Stress–Dependent Cyclooxygenase-2 Upregulation

Rationale:

Bone morphogenic protein (BMP)4 can stimulate superoxide production and exert proinflammatory effects on the endothelium. The underlying mechanisms of how BMP4 mediates endothelial dysfunction and hypertension remain elusive.

Objective:

To elucidate the cellular pathways by which BMP4-induced endothelial dysfunction is mediated through oxidative stress–dependent upregulation of cyclooxygenase (COX)-2.

Methods and Results:

Impaired endothelium-dependent relaxations, exaggerated endothelium-dependent contractions, and reactive oxygen species (ROS) production were observed in BMP4-treated mouse aortae, which were prevented by the BMP4 antagonist noggin. Pharmacological inhibition with thromboxane prostanoid receptor antagonist or COX-2 but not COX-1 inhibitor prevented BMP4-induced endothelial dysfunction, which was further confirmed with the use of COX-1 −/− or COX-2 −/− mice. Noggin and knockdown of BMP receptor 1A abolished endothelium-dependent contractions and COX-2 upregulation in BMP4-treated aortae. Apocynin and tempol treatment were effective in restoring endothelium-dependent relaxations, preventing endothelium-dependent contractions and eliminating ROS overproduction and COX-2 overexpression in BMP4-treated aortae. BMP4 increased p38 mitogen-activated protein kinase (MAPK) activity through a ROS-sensitive mechanism and p38 MAPK inhibitor prevented BMP4-induced endothelial dysfunction. COX-2 inhibition blocked the effect of BMP4 without affecting BMP4-induced ROS overproduction and COX-2 upregulation. Importantly, renal arteries from hypertensive rats and humans showed higher levels of COX-2 and BMP4 accompanied by endothelial dysfunction.

Conclusions:

We show for the first time that ROS serve as a pathological link between BMP4 stimulation and the downstream COX-2 upregulation in endothelial cells, leading to endothelial dysfunction through ROS-dependent p38 MAPK activation. This BMP4/ROS/COX-2 cascade is important in the maintenance of endothelial dysfunction in hypertension.

Role of specific microRNAs in regulation of vascular smooth muscle cell differentiation and the response to injury

Vascular smooth muscle cells (VSMCs) exhibit remarkable plasticity during postnatal development. Vascular injury initiates and perpetuates VSMCs dedifferentiation to a synthetic phenotype, which has been increasingly recognized to play a central role in neointimal hyperplasia during the pathogenesis of vascular proliferative diseases. MicroRNAs (miRNAs) are a novel class of regulatory noncoding RNAs that regulate gene expression at the posttranscriptional level by binding to 3' untranslated regions of target mRNAs, leading to either degrading mRNAs or inhibiting their translation. There is emerging evidence that miRNAs are critical regulators of widespread cellular functions such as differentiation, proliferation, and migration. Recent studies have indicated that a number of specific miRNAs play important roles in regulation of vascular cell functions and contribute to neointimal hyperplasia after vascular injury. Here, we review recent advance regarding functions of specific miRNAs in vasculature and discuss possible mechanisms by which miRNAs modulate proliferation and differentiation of VSMCs.

Ellagic acid inhibits oxidized LDL-mediated LOX-1 expression, ROS generation, and inflammation in human endothelial cells

BACKGROUND

LOX-1, a lectin-like receptor on endothelial cells, facilitates the uptake of oxidized low-density lipoprotein (oxLDL). Expression of LOX-1 is involved in the pathobiological effects of oxLDL in endothelial cells, including reactive oxygen species (ROS) generation, suppression of endothelial nitric oxide synthase (eNOS) activity, and leukocytic adhesion. Moderate consumption of phenolic-enriched food may have a protective effect against the development of atherosclerosis via the antioxidant capacity of phenolic compounds at the endothelial level. In this study, we determined whether ellagic acid, a polyphenolic compound widely distributed in fruits and nuts, protects against oxLDL-induced endothelial dysfunction by modulating the LOX-1-mediated signaling pathway.

METHODS

Human umbilical vein endothelial cells (HUVECs) were pretreated with ellagic acid at doses of 5, 10, 15, and 20 μM for 2 hours and then incubated with oxLDL (150 μg/mL) for an additional 24 hours.

RESULTS

LOX-1 protein expression was markedly lower after exposure to oxLDL in HUVECs pretreated with ellagic acid or diphenyleneiodonium, a well-known inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, than in HUVECs exposed to oxLDL alone, suggesting that ellagic acid deactivates NADPH oxidase. We also found that oxLDL activated the membrane assembly of p47phox, Rac1, gp91 and p22phox, and the subsequent induction of ROS generation; however, ROS generation was markedly suppressed in cells pretreated with ellagic acid or anti-LOX-1 monoclonal antibody. In addition, oxLDL down-regulated eNOS and up-regulated inducible NO synthase (iNOS), thereby augmenting the formation of NO and protein nitrosylation. Furthermore, oxLDL induced the phosphorylation of p38 mitogen-activated protein kinase, activated the NF-κB-mediated inflammatory signaling molecules interleukin-(IL) 6 and IL-8 and the adhesion molecules intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin, and stimulated the adherence of THP-1 (a human acute monocytic leukemia cell line) to HUVECs. Pretreatment with ellagic acid, however, exerted significant cytoprotective effects in all events.

CONCLUSION

Findings from this study may provide insight into a possible molecular mechanism by which ellagic acid inhibits LOX-1-induced endothelial dysfunction. Our data indicate that ellagic acid exerts its protective effects by inhibiting NADPH oxidase-induced overproduction of superoxide, suppressing the release of NO by down-regulating iNOS, enhancing cellular antioxidant defenses, and attenuating oxLDL-induced LOX-1 up-regulation and eNOS down-regulation.