Molecular aspects of atherogenesis: new insights and unsolved questions

Exploring the effects of vasoactive constituents in large cardamom: implications for the anti-hypertensive effect via eNOS coupling pathway - an in-vitro study in rat endothelial cells

Endothelial dysfunction, linked to reduced eNOS expression and nitric oxide (NO) availability, contributes to cardiovascular diseases (CVDs). Large cardamom exhibits antihypertensive effects by augmenting NO levels and antioxidant activity. To decipher its mechanisms, selected constituents were docked with eNOS-associated target genes such as GTP cyclohydrolase I (GTPCH-1) and (dihydrofolate reductase [DHFR]). Endothelial damage induced by L-NAME and fructose was countered by assessing nitric oxide metabolites (NOx), tetrahydrobipterin (BH4 levels), GCH-I expression and super oxide dismutase (SOD) activity after constituent incubation. Cyanidin-3-O-glucoside and petunidin-3-O-glucoside notably restored impaired vascular markers in both models. These phytoconstituents are likely to activate GCH-BH4-eNOS pathways, upregulating SOD and NO expression, maintaining endothelial integrity. Large cardamom's antihypertensive effects may stem from these components, synergistically enhancing endothelial NO release via the eNOS pathway.

Research Progress of Flavonoids Regulating Endothelial Function

The endothelium, as the guardian of vascular homeostasis, is closely related to the occurrence and development of cardiovascular diseases (CVDs). As an early marker of the development of a series of vascular diseases, endothelial dysfunction is often accompanied by oxidative stress and inflammatory response. Natural flavonoids in fruits, vegetables, and Chinese herbal medicines have been shown to induce and regulate endothelial cells and exert anti-inflammatory, anti-oxidative stress, and anti-aging effects in a large number of in vitro models and in vivo experiments so as to achieve the prevention and improvement of cardiovascular disease. Focusing on endothelial mediation, this paper introduces the signaling pathways involved in the improvement of endothelial dysfunction by common dietary and flavonoids in traditional Chinese medicine and describes them based on their metabolism in the human body and their relationship with the intestinal flora. The aim of this paper is to demonstrate the broad pharmacological activity and target development potential of flavonoids as food supplements and drug components in regulating endothelial function and thus in the prevention and treatment of cardiovascular diseases. This paper also introduces the application of some new nanoparticle carriers in order to improve their bioavailability in the human body and play a broader role in vascular protection.

Modulatory action of withaferin-A on oxidative damage through regulation of inflammatory mediators and apoptosis via PI3K/AKT signaling pathway in high cholesterol-induced atherosclerosis in experimental rats

Statins are widely used lipid-lowering drugs that cause many side effects. Withaferin-A (WA), popularly known as Ashwagandha, an ancient Indian medicinal herb, is extracted from Withania somnifera. Anti-atherosclerotic effect of WA has been reported. However, the mechanism remains unknown. Hence, we planned this study to investigate the WA mechanism in anti-atherosclerosis in a rat model. High cholesterol diet (HCD) was fed to induce atherosclerosis in Sprague-Dawley male rats. Five groups (N = 6 rats/group) were fed with normal diet, HCD, WA (10 mg/kg bw)+HCD, lovastatin (LS: 10 mg/kg bw)+HCD, WA (10 mg/kg bw) respectively for 90 days. Statistical analysis was done by GraphPad Prism (version 8.0.1) using one-way analysis of variance (ANOVA) followed by post hoc Duncan's test with a significance level (p < 0.05). The groups were compared for lipid profiles, oxidative stress, lipid peroxidation, inflammatory mediators, apoptotic markers, and histopathological changes in the liver and aorta. Treatment with HCD increased lipid profiles, inflammatory mediators, cytokines, and lipid peroxidation. WA as well as LS treatments significantly decreased these parameters restored the antioxidant status, and reduced lipid peroxidation (p < 0.05). Histopathological studies revealed that WA and LS reduced the hepatic fat and aortic plaque. WA reduced apoptosis via augmentation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway; increased B-cell lymphoma 2 and inhibited Bcl-2 associated X-protein proapoptotic proteins; TNF receptor superfamily member 6, Bim, caspase-3, and -9; demonstrated significant hypolipidemic and anti-inflammatory properties against HCD induced atherosclerosis in rats through regulation of inflammatory mediators and apoptosis via the PI3K/AKT signaling pathway.

N-Acetyl Cysteine, Selenium, and Ascorbic Acid Rescue Diabetic Cardiac Hypertrophy via Mitochondrial-Associated Redox Regulators

Metabolic disorders often lead to cardiac complications. Metabolic deregulations during diabetic conditions are linked to mitochondrial dysfunctions, which are the key contributing factors in cardiac hypertrophy. However, the underlying mechanisms involved in diabetes-induced cardiac hypertrophy are poorly understood. In the current study, we initially established a diabetic rat model by alloxan-administration, which was validated by peripheral glucose measurement. Diabetic rats displayed myocardial stiffness and fibrosis, changes in heart weight/body weight, heart weight/tibia length ratios, and enhanced size of myocytes, which altogether demonstrated the establishment of diabetic cardiac hypertrophy (DCH). Furthermore, we examined the expression of genes associated with mitochondrial signaling impairment. Our data show that the expression of PGC-1α, cytochrome c, MFN-2, and Drp-1 was deregulated. Mitochondrial-signaling impairment was further validated by redox-system dysregulation, which showed a significant increase in ROS and thiobarbituric acid reactive substances, both in serum and heart tissue, whereas the superoxide dismutase, catalase, and glutathione levels were decreased. Additionally, the expression levels of pro-apoptotic gene PUMA and stress marker GATA-4 genes were elevated, whereas ARC, PPARα, and Bcl-2 expression levels were decreased in the heart tissues of diabetic rats. Importantly, these alloxan-induced impairments were rescued by N-acetyl cysteine, ascorbic acid, and selenium treatment. This was demonstrated by the amelioration of myocardial stiffness, fibrosis, mitochondrial gene expression, lipid profile, restoration of myocyte size, reduced oxidative stress, and the activation of enzymes associated with antioxidant activities. Altogether, these data indicate that the improvement of mitochondrial dysfunction by protective agents such as N-acetyl cysteine, selenium, and ascorbic acid could rescue diabetes-associated cardiac complications, including DCH.

Is smoking a risk factor for bleeding in adult men with cerebral arteriovenous malformations? A single-center regression study from China

OBJECTIVE

To assess whether smoking increases the risk of bleeding in patients with cerebral arteriovenous malformations (CAVM).

MATERIAL AND METHODS

According to our research plan, 385 CAVM patients admitted to Beijing Tiantan Hospital from December 2015 to January 2018 were included in this study, including 210 bleeding patients and 175 non-bleeding patients. We divided patients into three subgroups of current smokers, ex-smokers (those who quit smoking for one year or more) and non-smokers. The relationship between smoking and the risk of CAVM rupture was assessed by univariate and multivariate regression analysis.

RESULTS

Multivariate regression analysis showed that there was a statistically significant difference between current smoker and non-smoker (OR = 1.87, p = 0.019). Among the covariates of the multivariate regression analysis, the location, combined with blood flow-related intracranial aneurysms and size were related to the risk of CAVM bleeding.

CONCLUSION

Current smoking may increase the risk of CAVM bleeding; however, there was no significant correlation between ex-smoking and CAVM bleeding.

Severe hypoglycemia exacerbates myocardial dysfunction and metabolic remodeling in diabetic mice

Although several studies have revealed that adverse cardiovascular events in diabetic patients are closely associated with severe hypoglycemia (SH), the causal relationship and related mechanisms remain unclear. This study aims to investigate whether SH promotes myocardial injury and further explores the potential mechanisms with focus on disturbances in lipid metabolism. SH promoted myocardial dysfunction and structural disorders in the diabetic mice but not in the controls. SH also enhanced the production of myocardial proinflammatory cytokines and oxidative stress. Moreover, myocardial lipid deposition developed in diabetic mice after SH, which was closely related to myocardial dysfunction and the inflammatory response. We further found that myocardial metabolic remodeling was associated with changes in PPAR-β/δ and its target molecules in diabetic mice exposed to SH. These findings demonstrate that SH exacerbates myocardial dysfunction and the inflammatory response in diabetic mice, which may be induced by myocardial metabolic remodeling via PPAR-β/δ.

Physical activity in the prevention of human diseases: role of epigenetic modifications

Epigenetic modification refers to heritable changes in gene function that cannot be explained by alterations in the DNA sequence. The current literature clearly demonstrates that the epigenetic response is highly dynamic and influenced by different biological and environmental factors such as aging, nutrient availability and physical exercise. As such, it is well accepted that physical activity and exercise can modulate gene expression through epigenetic alternations although the type and duration of exercise eliciting specific epigenetic effects that can result in health benefits and prevent chronic diseases remains to be determined. This review highlights the most significant findings from epigenetic studies involving physical activity/exercise interventions known to benefit chronic diseases such as metabolic syndrome, diabetes, cancer, cardiovascular and neurodegenerative diseases.

PPARs modulate cardiac metabolism and mitochondrial function in diabetes

Diabetic cardiomyopathy is a major complication of diabetes mellitus (DM). Currently, effective treatments for diabetic cardiomyopathy are limited. The pathophysiology of diabetic cardiomyopathy is complex, whereas mitochondrial dysfunction plays a vital role in the genesis of diabetic cardiomyopathy. Metabolic regulation targeting mitochondrial dysfunction is expected to be a reasonable strategy for treating diabetic cardiomyopathy. Peroxisome proliferator-activated receptors (PPARs) are master executors in regulating glucose and lipid homeostasis and also modulate mitochondrial function. However, synthetic PPAR agonists used for treating hyperlipidemia and DM have shown controversial effects on cardiovascular regulation. This article reviews our updated understanding of the beneficial and detrimental effects of PPARs on mitochondria in diabetic hearts.

LXR agonist T0901317 upregulates thrombomodulin expression in glomerular endothelial cells by inhibition of nuclear factor‑κB

Dysfunction of glomerular endothelial cells (GECs) induces a variety of symptoms, including proteinuria, inflammation, vascular diseases, fibrosis and thrombosis. Thrombomodulin (TM) acts as a vasoprotective molecule on the surface of the vascular endothelial cells to maintain the homeostasis of the endothelial microenvironment by suppressing cellular proliferation, adhesion and inflammatory responses. Liver X receptor (LXR), a nuclear receptor (NR) and a bile acid‑activated transcription factor, regulates metabolism and cholesterol transport, vascular tension and inflammation. Previous studies indicated that TM expression is upregulated by various NRs; however, it is unclear whether pharmacological modulation of LXR may affect TM expression and GEC function. The current study revealed that LXR activation by its agonist, T0901317, upregulates the expression and activity of TM. This effect was mediated specifically through LXR‑α, and not through LXR‑β. Additionally, T0901317 treatment inhibited nuclear factor‑κB (NF‑κB) signaling and the secretion of high glucose‑induced proinflammatory mediators, including tumor necrosis factor‑α and interleukin‑1β in GECs. Co‑immunoprecipitation experiments determined that treatment with T0901317 enhances the interaction between LXR‑α and the transcriptional coactivator, p300, in GEC extracts. The present findings suggest that NF‑κB may be a negative regulator of TM expression, and its removal may contribute to TM gene expression, particularly when in competition with the T0901317‑enhanced formation of the LXR/p300 complex. Therefore, LXR may be a novel molecular target for manipulating TM in GECs, which may advance the treatment of endothelial cell‑associated diseases.

Periodontal disease in relation to selected parameters of the cardiovascular system in a group of patients with stable angina pectoris

Introduction

Periodontal diseases (PD), which are the cause of chronic inflammatory processes, can develop increased susceptibility to vascular diseases through atherosclerosis. Due to the raised inflammatory and thrombotic risk, PD can have a significant influence on the course and results of stable angina pectoris (SAP).

Objectives

The aim of the study is to evaluate the influence of chosen PD parameters on selected cardiovascular system parameters, and the correlation between chosen parameters of periodontitis and cardiovascular system parameters.

Material and methods

The case group included 67 patients with SAP, ≤ 60 years of age. The occurrence of well-known cardiovascular disease risk factors was evaluated on the basis of the clinical interview, clinical examination and laboratory tests. The occurrence of known risk factors for cardiovascular diseases (CVD) was established on the basis of the interview, clinical research and laboratory tests. Periodontal examination included API (approximal plaque index), CAL (clinical attachment level), PD (pocket depth), and BI (bleeding index). IMT (intima-media thickness) and the size of atherosclerotic plaque in carotid arteries were assessed by ultrasound examination. Segmental contractility abnormalities were assessed on the basis of echocardiography examination, presence of the single-vessel vascular and multi-vessel vascular disease on the basis of angiographic examination.

Results

In the study group of patients, numerous risk factors and a higher level of API, CAL, PD and BI were observed. A higher prevalence of multi-vessel disease (75%) than single-vessel disease (25%) was noted on the basis of angiographic examination. Patients with contractility abnormalities demonstrated also poor oral cavity health. In addition, a higher concentration of CRP (3.2 mg/dl), fibrinogen (3.3 g/l)) and the progression of atherosclerosis, e.g. increased IMT (2.1 mm) and formation of atherosclerotic plaques were noted. Results of multivariate logistic regression demonstrated that API and PD had a significant influence on IMT. In patients with BMI ≥ 30 kg/m², the risk of increased IMT (OR = 4.67) was fourfold higher.

Summary

Periodontitis may influence the occurrence and course of the atherosclerotic process in persons with stable angina.

Transcription of liver X receptor is down-regulated by 15-deoxy-Δ(12,14)-prostaglandin J(2) through oxidative stress in human neutrophils

Liver X receptors (LXRs) are ligand-activated transcription factors of the nuclear receptor superfamily. They play important roles in controlling cholesterol homeostasis and as regulators of inflammatory gene expression and innate immunity, by blunting the induction of classical pro-inflammatory genes. However, opposite data have also been reported on the consequences of LXR activation by oxysterols, resulting in the specific production of potent pro-inflammatory cytokines and reactive oxygen species (ROS). The effect of the inflammatory state on the expression of LXRs has not been studied in human cells, and constitutes the main aim of the present work. Our data show that when human neutrophils are triggered with synthetic ligands, the synthesis of LXRα mRNA became activated together with transcription of the LXR target genes ABCA1, ABCG1 and SREBP1c. An inflammatory mediator, 15-deoxy-Δ^12,14-prostaglandin J₂ (15dPGJ₂), hindered T0901317-promoted induction of LXRα mRNA expression together with transcription of its target genes in both neutrophils and human macrophages. This down-regulatory effect was dependent on the release of reactive oxygen species elicited by 15dPGJ₂, since it was enhanced by pro-oxidant treatment and reversed by antioxidants, and was also mediated by ERK1/2 activation. Present data also support that the 15dPGJ₂-induced serine phosphorylation of the LXRα molecule is mediated by ERK1/2. These results allow to postulate that down-regulation of LXR cellular levels by pro-inflammatory stimuli might be involved in the development of different vascular diseases, such as atherosclerosis.

The methyl xanthine caffeine inhibits DNA damage signaling and reactive species and reduces atherosclerosis in ApoE(-/-) mice

OBJECTIVE

Caffeine remains one of the most widely consumed drugs in the world. Caffeine has multiple actions, including inhibition of the DNA damage response, and its metabolites, 1-methylxanthine and 1-methyluric acid, are potent antioxidants. Combined, these properties can exert direct effects on cell proliferation, cell death, inflammation, and DNA repair, all important processes that occur in atherosclerosis.

METHODS AND RESULTS

We first examined the effects of caffeine on mouse vascular smooth muscle cells. Caffeine inhibited activation of the DNA damage response regulator ataxia telangiectasia mutated protein and its downstream targets. Caffeine delayed DNA repair, had a concentration-dependent effect on cell proliferation, and protected against apoptosis. In vitro caffeine reduced oxygen consumption and decreased generation of reactive oxygen species. In vivo caffeine reduced DDR activation in vascular and nonvascular tissues, reduced reactive nitrogen species and serum levels of the DNA adduct 8-oxo-guanine, and inhibited atherogenesis in fat-fed ApoE(-/-) mice. Reduction in atherosclerosis was independent of the effects on blood pressure and serum lipids but associated with reduced cell proliferation and ataxia telangiectasia mutated protein activation.

CONCLUSIONS

The Methyl Xanthine caffeine inhibits the DNA damage response in vitro and in vivo, regulates both cell proliferation and apoptosis after DNA damage, inhibits reactive species, and reduces atherogenesis in ApoE(-/-) mice.

[Pathogenetic justification of statin use in ischaemic stroke prevention according to inflammatory theory in development of atherosclerosis]

There is an inflammatory component in the pathogenesis of ischaemic stroke, which plays an important role in inducing atherothrombotic and embolic stroke. Statins, HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase inhibitors are widely used in the primary and secondary prevention of ischaemic stroke. It has been proved that beyond their main effect on inhibition of endogenous cholesterol, they also modify the inflammatory process. Additional benefits from the use of statins result from their effect on the immune system. Increased risk of recurrent vascular episodes and risk of death after statin withdrawal in patients with vascular disorders is connected with termination of the anti-inflammatory effect of these drugs. The authors highlight that because of the anti-inflammatory effect of statins it is reasonable to use them in all patients at risk of ischaemic stroke, including those with atrial fibrillation.

Benefit of Monascus-fermented products for hypertension prevention: a review

γ-Aminobutyric acid (GABA) has been reported to play a neurotransmitter in the central nervous system thereby exerting an inhibition in nerve impulse, in turn ameliorating depression; in addition, recent study also reveals the anti-hypertensive effect of GABA in vivo. Edible fungi of the Monascus species have been used as traditional Chinese medicine in eastern Asia for several centuries. Monascus-fermented products possess a number of functional secondary metabolites, including anti-inflammatory pigments (such as monascin and ankaflavin), monacolins, dimerumic acid, and GABA. Several scientific studies have shown that these secondary metabolites have anti-inflammatory, anti-oxidative, and anti-tumor activities. Moreover, many published reports have shown the efficacy of Monascus-fermented products in the prevention or amelioration of some diseases, including hypercholesterolemia, hyperlipidemia, hypertension, diabetes, obesity, Alzheimer's disease, and numerous types of cancer in recent studies. The current article discusses and provides evidence to elucidate the anti-hypertensive benefit of Monascus-fermented metabolites, including anti-inflammatory pigments and GABA.

Inhibition of endothelial adhesion molecule expression by Monascus purpureus-fermented rice metabolites, monacolin K, ankaflavin, and monascin

BACKGROUND

Inflammation is an independent risk factor of cardiovascular diseases and is associated with endothelial dysfunction. Monascus purpureus-fermented rice, containing naturally occurring statins and various pigments, has lipid-modulating, anti-inflammatory and antioxidative effects.

RESULTS

The effects of monacolin K, ankaflavin and monascin, as metabolites from Monascus-fermented rice, on the expression of cell adhesion molecules (intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecular-1 (VCAM-1) and E-selectin) by tumor necrosis factor (TNF)-α-treated human aortic endothelial cells (HAECs) were investigated. Supplement of HAECs with these Monascus-fermented rice metabolites significantly suppressed cellular binding between the human monocytic cells U937 and TNF-α-stimulated HAECs. Immunoblot analysis showed that Monascus-fermented rice metabolites significantly attenuated TNF-α-induced VCAM-1 and E-selectin but not ICAM-1 protein expression. Gel shift assays showed that Monascus-fermented rice metabolites treatment reduced TNF-α-activated transcription factor nuclear factor (NF)-κB. Furthermore, Monascus-fermented rice metabolites also attenuated reactive oxygen species (ROS) generation in vitro and in TNF-α-treated HAECs. Supplement with an ROS scavenger N-acetylcysteine gave similar results as compared with Monascus-fermented rice metabolites.

CONCLUSION

Monascus-fermented rice metabolites reduced TNF-α-stimulated endothelial adhesiveness as well as downregulating intracellular ROS formation, NF-κB activation, and VCAM-1/E-selectin expression in HAECs, supporting the notion that the various metabolites from Monascus-fermented rice might have potential implications in clinical atherosclerosis disease.

Ligustrazine improves atherosclerosis in rat via attenuation of oxidative stress

CONTEXT

Ligustrazine (Lig) is a compound isolated from the rhizome of Ligusticum chuanxiong Hort. (Umbelliferae) and has been reported to be effective for the treatment of a variety of vascular diseases.

OBJECTIVE

The anti-atherosclerotic activities of Lig are evaluated in vivo for the first time in the present study.

MATERIALS AND METHODS

We gave rats a single injection of vitamin D3 and then fed them with an atherogenic diet for 6 weeks to induce atherosclerosis. Lig was simultaneously given to rats by gavage at the dose of 20 or 80 mg/kg in the therapy groups. Multiple approaches including spectrophotometry, hematoxylin and eosin (H&E) staining, and quantitative RT-PCR were applied to investigate the effects of Lig on blood parameters, aorta and liver histology, and gene expression. In addition, the solely effects of Lig on food intake, body weight gain, and taste preference were also evaluated.

RESULTS

We found that two doses of Lig treatment decreased the total cholesterol levels by 65.2 and 76.7%, respectively, in the plasma. Triglyceride (by 53.2 and 77.9%) and low-density lipoprotein (by 71.2 and 79.0%) levels were also decreased. However, high-density lipoprotein level was slightly increased. The circulating endothelial cells were decreased by 42.2 and 60.0% in Lig-treated rats, indicating the attenuation of endothelial injury. In contrast, Lig restored the total antioxidant capacity and superoxide dismutase 1 (SOD1) activity while decreasing the MDA generation. Furthermore, Lig improved liver dysfunction by decreasing ALT (by 13.0 and 49.7%) and AST (by 10.7 and 14.3%) levels. Histological examinations revealed that Lig suppressed atherosclerotic plaque progression in the thoracic aorta and lipid accumulation in the liver. At the transcriptional level, Lig inhibited the induction of antioxidant genes both in aorta and in liver. Lig also suppressed the mRNA expression of the genes involved in the hepatic fatty acid oxidation. Finally, Lig had a minimum effect on food intake, body weight gain, and taste preference.

DISCUSSION AND CONCLUSION

Our results suggest that Lig suppresses the development of atherosclerosis and hepatic lipid accumulation via the alleviation of oxidative stress and the improvement of dyslipidemia.

Investigation of the oxidative effect of chronic hyperammonemia on the kidney and the possible protective effect of allopurinol

Although there have been many studies on this topic, the molecular mechanism of the toxic effects of hyperammonemia on cells has not yet been fully explained. Recent studies have held oxidative stress mechanisms responsible for hyperammonemia-induced cell damage. Kidney functions are affected in diseases associated with an increase in ammonia in the blood. Our study tries to determine whether oxidative stress mechanisms are responsible for kidney damage in chronic hyperammonemia. We also investigated whether kidney damage is dependent on possible reactive oxygen products associated with the xanthine oxidase (XO) enzyme and whether the possible association can be inhibited with allopurinol, an XO enzyme inhibitor. The study took into consideration the enzyme activities of XO, xanthine dehydrogenase (XDH), superoxide dismutase (SOD), glutathione-S-transferase (GST), as well as protein thiol (P-SH) and malondialdehyde (MDA) levels. The data found demonstrated that chronic hyperammonemia had oxidative stress effects on the kidney, and that kidney XO and XDH activity changed. However, it was not possible to inhibit this oxidative stress in the kidney using allopurinol. Thus, we could not conclude that oxidative stress is an XO-dependent mechanism. The outcomes of the study suggested that this oxidative situation arising in hyperammonemia occurred through a mechanism other than the XO enzyme.

Targeting the neurovascular unit for treatment of neurological disorders

Drug discovery for CNS disorders has been restricted by the inability for therapeutic agents to cross the blood-brain barrier (BBB). Moreover, current drugs aim to correct neuron cell signaling, thereby neglecting pathophysiological changes affecting other cell types of the neurovascular unit (NVU). Components of the NVU (pericytes, microglia, astrocytes, and neurons, and basal lamina) act as an intricate network to maintain the neuronal homeostatic microenvironment. Consequently, disruptions to this intricate cell network lead to neuron malfunction and symptoms characteristic of CNS diseases. A lack of understanding in NVU signaling cascades may explain why current treatments for CNS diseases are not curative. Current therapies treat symptoms by maintaining neuron function. Refocusing drug discovery to sustain NVU function may provide a better method of treatment by promoting neuron survival. In this review, we will examine current therapeutics for common CNS diseases, describe the importance of the NVU in cerebral homeostasis and discuss new possible drug targets and technologies that aim to improve treatment and drug delivery to the diseased brain.

DNA damage links mitochondrial dysfunction to atherosclerosis and the metabolic syndrome

RATIONALE

DNA damage is present in both genomic and mitochondrial DNA in atherosclerosis. However, whether DNA damage itself promotes atherosclerosis, or is simply a byproduct of the risk factors that promote atherosclerosis, is unknown.

OBJECTIVE

To examine the effect of DNA damage on atherosclerosis, we studied apolipoprotein (Apo)E(-/-) mice that were haploinsufficient for the protein kinase ATM (ataxia telangiectasia mutated), which coordinates DNA repair.

METHODS AND RESULTS

ATM(+/-)/ApoE(-/-) mice developed accelerated atherosclerosis and multiple features of the metabolic syndrome, including hypertension, hypercholesterolemia, obesity, steatohepatitis, and glucose intolerance. Transplantation with ATM(+/+) bone marrow attenuated atherosclerosis but not the metabolic syndrome. ATM(+/-) smooth muscle cells and macrophages showed increased nuclear DNA damage and defective DNA repair signaling, growth arrest, and apoptosis. Metabolomic screening of ATM(+/-)/ApoE(-/-) mouse tissues identified metabolic changes compatible with mitochondrial defects, with increased β-hydroxybutyrate but reduced lactate, reduced glucose, and alterations in multiple lipid species. ATM(+/-)/ApoE(-/-) mouse tissues showed an increased frequency of a mouse mitochondrial "common" deletion equivalent and reduced mitochondrial oxidative phosphorylation.

CONCLUSIONS

We propose that failure of DNA repair generates defects in cell proliferation, apoptosis, and mitochondrial dysfunction. This in turn leads to ketosis, hyperlipidemia, and increased fat storage, promoting atherosclerosis and the metabolic syndrome. Prevention of mitochondrial dysfunction may represent a novel target in cardiovascular disease.

Tetrahydrobiopterin Inhibits PDGF-stimulated Migration and Proliferation in Rat Aortic Smooth Muscle Cells via the Nitric Oxide Synthase-independent Pathway

Tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide synthase (NOS) activity, is known to play important roles in modulating both NO and superoxide production during vascular diseases such as atherosclerosis. However, the role of BH4 in functions of vascular smooth muscle cells is not fully known. In this study, we tested the effects of BH4 and dihydrobiopterin (BH2), a BH4 precursor, on migration and proliferation in response to platelet-derived growth factor-BB (PDGF-BB) in rat aortic smooth muscle cells (RASMCs). Cell migration and proliferation were measured using a Boyden chamber and a 5-bromo-2'-deoxyuridine incorporation assay, respectively, and these results were confirmed with an ex vivo aortic sprout assay. Cell viability was examined by 2,3-bis [2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide assays. BH4 and BH2 decreased PDGF-BB-induced cell migration and proliferation in a dose-dependent manner. The inhibition of cell migration and proliferation by BH4 and BH2 was not affected by pretreatment with N(G)-nitro-L-arginine methyl ester, a NOS inhibitor. Moreover, the sprout outgrowth formation of aortic rings induced by PDGF-BB was inhibited by BH4 and BH2. Cell viability was not inhibited by BH4 and BH2 treatment. The present results suggest that BH4 and BH2 may inhibit PDGF-stimulated RASMC migration and proliferation via the NOS-independent pathway. Therefore, BH4 and its derivative could be useful for the development of a candidate molecule with an NO-independent anti-atherosclerotic function.

Endothelial nitric oxide synthase Glu298Asp, 4b/a, and -786T>C gene polymorphisms and the risk of ischemic stroke

BACKGROUND AND PURPOSE

Endothelial nitric oxide synthase (eNOS) gene polymorphisms were associated with reduced NO production, and were evaluated as risk factors for ischemic stroke (IS). We investigated the association between eNOS gene -786T>C (promoter), 27-bp repeat 4b/4a (intron 4), and Glu298Asp (exon 7) polymorphisms with IS in 329 IS patients and 444 controls.

MATERIALS AND METHODS

Glu298Asp and -786T>C genotyping was done by PCR-RFLP, 4b/4a was assessed by PCR-ASA. The contribution of eNOS polymorphisms to IS was analyzed by haplotype and multivariate regression analysis.

RESULTS

Higher frequency of 298Asp allele was seen in IS patients (P = 1.2 x 10(-10)), which remained independently associated with IS on multivariate analysis after controlling for traditional cerebrovascular risk factors. Allele and genotype distribution of 4b/4a and -786T>C polymorphisms were comparable between patient and controls. Significantly higher prevalence of 298Asp/4b/-786T and 298Asp/4b/-786C haplotypes were seen in IS cases, thus conferring a disease susceptibility nature to these haplotypes. Multivariate regression analysis confirmed the association of 298Asp/4b/-786T and 298Asp/4b/-786C haplotypes, and in addition identified 298Asp/4a/-786T haplotype to be independently associated with IS, after controlling for traditional cerebrovascular risk factors.

CONCLUSIONS

Genetic variation at the eNOS locus represent genetic risk factor for increased susceptibility to IS.

The emerging role of cardiovascular risk factor-induced mitochondrial dysfunction in atherogenesis

An important role in atherogenesis is played by oxidative stress, which may be induced by common risk factors. Mitochondria are both sources and targets of reactive oxygen species, and there is growing evidence that mitochondrial dysfunction may be a relevant intermediate mechanism by which cardiovascular risk factors lead to the formation of vascular lesions. Mitochondrial DNA is probably the most sensitive cellular target of reactive oxygen species. Damage to mitochondrial DNA correlates with the extent of atherosclerosis. Several cardiovascular risk factors are demonstrated causes of mitochondrial damage. Oxidized low density lipoprotein and hyperglycemia may induce the production of reactive oxygen species in mitochondria of macrophages and endothelial cells. Conversely, reactive oxygen species may favor the development of type 2 diabetes mellitus, mainly through the induction of insulin resistance. Similarly - in addition to being a cause of endothelial dysfunction, reactive oxygen species and subsequent mitochondrial dysfunction - hypertension may develop in the presence of mitochondrial DNA mutations. Finally, other risk factors, such as aging, hyperhomocysteinemia and cigarette smoking, are also associated with mitochondrial damage and an increased production of free radicals. So far clinical studies have been unable to demonstrate that antioxidants have any effect on human atherogenesis. Mitochondrial targeted antioxidants might provide more significant results.

Transmembrane signaling pathway mediates oxidized low-density lipoprotein-induced expression of plasminogen activator inhibitor-1 in vascular endothelial cells

Atherosclerotic cardiovascular disease is the number one cause of death for adults in Western society. Plasminogen activator inhibitor-1 (PAI-1), the major physiological inhibitor of plasminogen activators, has been implicated in both thrombogenesis and atherogenesis. Previous studies demonstrated that copper-oxidized low-density lipoprotein (C-oLDL) stimulated production of PAI-1 in vascular endothelial cells (EC). The present study examined the involvement of lectin-like oxidized LDL receptor-1 (LOX-1) and Ras/Raf-1/ERK1/2 pathway in the upregulation of PAI-1 in cultured EC induced by oxidized LDLs. The results demonstrated that C-oLDL or FeSO(4)-oxidized LDL (F-oLDL) increased the expression of PAI-1 or LOX-1 in human umbilical vein EC (HUVEC) or coronary artery EC (HCAEC). Treatment with C-oLDL significantly increased the levels of H-Ras mRNA, protein, and the translocation of H-Ras to membrane fraction in EC. LOX-1 blocking antibody, Ras farnesylation inhibitor (FTI-277), or small interference RNA against H-Ras significantly reduced C-oLDL or LDL-induced expression of H-Ras and PAI-1 in EC. Incubation with C-oLDL or F-oLDL increased the phosphorylation of Raf-1 and ERK1/2 in EC compared with LDL or vehicle. Treatment with Raf-1 inhibitor blocked Raf-1 phosphorylation and the elevation of PAI-1 mRNA level in EC induced by C-oLDL or LDL. Treatment with PD-98059, an ERK1/2 inhibitor, blocked C-oLDL or LDL-induced ERK1/2 phosphorylation or PAI-1 expression in EC. The results suggest that LOX-1, H-Ras, and Raf-1/ERK1/2 are implicated in PAI-1 expression induced by oxidized LDLs or LDL in cultured EC.

Contractility-dependent modulation of cell proliferation and adhesion by microscale topographical cues

Engineering of cellular assembly on biomaterial scaffolds by utilizing microscale topographical cues has emerged as a powerful strategy in cardiovascular tissue engineering and regenerative medicine. However, the mechanisms through which these cues are processed to yield changes in canonical cell behaviors remain unclear. Previously, we showed that when mixtures of cardiomyocytes and fibroblasts were cultured on polydimethylsiloxane surfaces studded with microscale pillars (micropegs), fibroblast proliferation was dramatically suppressed, which suggests that the micropegs could be exploited to minimize fibrosis and scar formation. Here, we demonstrate that this effect relies on altered adhesive and micromechanical interactions between individual cells and micropegs. First, we show that the proliferation of a cell physically attached to a micropeg is significantly lower than that of a cell cultured on a featureless region of the substrate. Micropeg adhesion is accompanied by a marked elongation in cell and nuclear shape. When fibroblast contractility is pharmacologically attenuated through low-dose inhibition of either Rho-associated kinase or myosin light chain kinase, the potency with which micropeg adhesion suppresses cell proliferation is significantly reduced. Together, our results support a model in which cell fate decisions may be directly manipulated within tissue engineering scaffolds by the inclusion of microtopographical structures that alter cellular mechanics.

Ostial Lesions of Left Main and Right Coronary Arteries: Demographic and Angiographic Features

In 258 patients with left main tract disease, the atherosclerotic risk factors were compared between patients with ostial and nonostial lesions of the left main coronary artery. Also, it was done for patients with ostial right coronary artery. Women were more likely to have ostial left main coronary artery and/or ostial right coronary artery. A multivariate logistic regression analysis revealed that the female sex (odds ratio: 2.336) and hypertriglyceridemia (odds ratio: 1.004) were independent risk factors of ostial left main coronary artery lesion. For ostial right coronary artery lesion, the female sex and family history of coronary artery disease were independent predictors. Ostial left main coronary artery and right coronary artery lesions were strongly correlated. The demographic and clinical profiles of ostial stenosis suggest that this group may represent a distinct entity, different from the more common atherosclerotic left main trunk stenosis (LMTD). The female sex and serum triglyceride level can be considered as independent predictors of ostial left main tract disease.

Peripheral blood mononuclear cells (PBMCs): a possible model for studying cardiovascular biology systems

BACKGROUND

The inflammation system, alone or in relation to or interaction with other cardiovascular pathways, is suggested to be the central pathway in the development and progression of cardiovascular diseases. The aim of the present investigation was to propose a specific and informative model for exploring this hypothesis.

METHODS

In a biological system approach, we studied the expression of 182 candidate cardiovascular genes in peripheral blood mononuclear cells (PBMCs), cells that provide specific information on the inflammatory pathway. We explored their expression in 20 individuals with or without risk factors (obesity, hypertension) for cardiovascular disease.

RESULTS

We found that: 1) 166 among the 182 selected genes were expressed in at least one individual's PBMCs, some of them being detected for the first time in this tissue; 2) all pathways were represented by the majority of their genes selected; 3) genes were expressed at a level sufficient for further study of the inter-individual variations in their mRNA to determine their biological variation; and 4) 15 genes discriminated hypertensive from obese or controls.

CONCLUSIONS

The results of the present investigation support our proposal of a promising novel strategy based on PBMC transcriptomic studies to elucidate the complexity of the cardiovascular system in relation to inflammation. Preliminary data support the usefulness of the PBMC model in hypertension/inflammation research.

The putative role of mitochondrial dysfunction in hypertension

Hypertension is a condition associated with oxidative stress, endothelial dysfunction, and increased vascular resistance, representing probably both a cause and a consequence of elevated levels of reactive oxygen (ROS) and nitrogen (RNS) species. Mitochondria are important sites of ROS production, and a mitochondrial dysfunction, preceding endothelial dysfunction, might favor the development of hypertension. ROS production may also be induced by RNS, which inhibit the respiratory chain and may be generated through the action of a mitochondrial NO synthase. Mitochondrial uncoupling proteins are involved in both experimental and human hypertension. Finally, an excessive production of ROS may damage mitochondrial DNA, with resultant impairment in the synthesis of some components of the respiratory chain and further ROS production, a vicious cycle that may be implicated in hypertensive states.

Cholestin (Monascus purpureus rice) inhibits homocysteine-induced reactive oxygen species generation, nuclear factor-κB activation, and vascular cell adhesion molecule-1 expression in human aortic endothelial cells

Hyperhomocysteinemia is associated with dysfunction and an independent risk factor of cardiovascular diseases. Cholestin (Monascus purpureus-fermented rice), contains a naturally-occurring statin, which has lipid-modulating and anti-inflammatory effects. We investigated the effects of Cholestin extract on the expression of vascular cell adhesion molecule-1 (VCAM-1) by homocysteine (HCY)-treated human aortic endothelial cells (HAECs). Supplement of HAECs with Cholestin extract significantly suppressed cellular binding between the human monocytic cells U937 and HCY-stimulated HAECs. Quantitative PCR and immunoblot analysis showed that Cholestin extract significantly attenuated HCY-induced expression of VCAM-1 mRNA and protein, respectively. Gel shift assays showed that Cholestin treatment reduced HCY-activated transcription factor nuclear factor-kappaB (NF-kappaB). Furthermore, Cholestin also attenuated reactive oxygen species (ROS) generation in vitro and in HCY-treated HAECs. Supplement with statins including simvastatin and parastatin gave similar results as compared with Cholestin. In conclusion, Cholestin reduces HCY-stimulated endothelial adhesiveness as well as downregulating intracellular ROS formation, NF-kappaB activation, and VCAM-1 expression in HAECs, supporting the notion that the natural compound Cholestin may have potential implications in clinical atherosclerosis disease.

SELDI-TOF mass spectrometry of High-Density Lipoprotein

Background

High-Density Lipoprotein (HDL), one of the main plasma lipoproteins, serves as a docking station for proteins involved in inflammation, coagulation, and lipid metabolism.

Methods

To elucidate the protein composition of HDL, we employed SELDI-TOF mass spectrometry as a potential high-throughput proteomic candidate for protein profiling of HDL. HDL derived from normolipemic individuals was captured on PS20 protein-chips using covalently bound antibodies against apo A-I or A-II.

Results

After optimisation, on-chip capture of HDL particles directly from plasma or from pre-purified HDL resulted in comparable fingerprints confirming specific capture of HDL. Depending on the capture antibody some differences in the fingerprint were observed. The most detailed fingerprint was observed up to 50 kDa; approximately 95 peaks were detected in the 3–50 kDa molecular mass range. Between 50 and 160 kDa, 27 more peaks were detected.

Conclusion

Based on these results, SELDI-TOF MS may be a suitable high-throughput candidate for HDL protein profiling and marker search. This approach may be used to i) investigate the underlying mechanisms that lead to increased atherothrombotic risk and ii) to investigate the atherothrombotic state of an individual.

Endothelial gap junctions are down-regulated by arsenic trioxide

We investigated the effect of As(2)O(3), an anti-cancer drug, on endothelial gap junctions. Human aortic endothelial cells (HAEC) were treated with As(2)O(3) at 1, 10, 100, and 1000 ng/ml and the cells were examined to evaluate the expression of connexin43 (Cx43) and to assess gap-junction communication. Endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) were measured to assess for endothelial dysfunction. Male Sprague-Dawley rats were given intravenous As(2)O(3) (200 mug/kg/day) or saline for 4 weeks, after which aortic endothelial gap junctions, eNOS, and circulating NO levels were evaluated. We found that HAEC Cx43 transcripts and gap junctions were reduced and gap-junction communication was attenuated by As(2)O(3). This decrease of Cx43 gap junctions was prevented by the addition of protease inhibitors. At a dose of 100 ng/ml of As(2)O(3), eNOS was reduced at 48 h, but NO was markedly reduced by 1 h. In animals treated with As(2)O(3), endothelial gap junctions comprising Cx37, Cx40, or Cx43 were all reduced in amount, while eNOS and circulating NO levels remained unchanged. In both in vitro and in vivo rat experiments, endothelial gap junctions were consistently reduced by As(2)O(3), unlike the response of eNOS and NO, which were decreased in cells but not in the rat aortic endothelium. The reduction in Cx43 involved both down-regulation at the transcriptional level and increased degradation. These findings indicate that gap-junction communication in the vascular endothelium is inhibited by treatment with As(2)O(3).

The role of tobacco smoke induced mitochondrial damage in vascular dysfunction and atherosclerosis

The majority of individuals chronically exposed to tobacco smoke will eventually succumb to cardiovascular disease (CVD). However, despite the major cardiovascular health implications of tobacco smoke exposure, concepts of how such exposure specifically results in cardiovascular cell dysfunction that leads to CVD development are still being explored. Moreover, surprisingly little is known about the effects of prenatal and childhood tobacco smoke exposure on adult CVD development. Herein, it is proposed that the mitochondrion is a central target for environmental oxidants, including tobacco smoke. By virtue of its multiple, essential roles in cell function including energy production, oxidant signaling, apoptosis, immune response, and thermogenesis, damage to the mitochondrion will likely play an important role in the development of multiple common forms of human disease, including CVD. Specifically, this review will discuss the potential role of tobacco smoke and environmental oxidant exposure in the induction of mitochondrial damage which is related to CVD development. Furthermore, mechanisms of how mitochondrial damage can initiate and/or contribute to CVD are discussed, as are experimental results that are consistent with the hypothesis that mitochondrial damage and dysfunction will increase CVD susceptibility. Aspects of both adult and developmental (fetal and childhood) exposure to tobacco smoke on mitochondrial damage, function and disease development are also discussed, including the future implications and direction of studies involving the role of the mitochondrion in influencing disease susceptibility mediated by environmental factors.

Oxidative Stress in Uremia: The Role of Anemia Correction: Table 1

Patients with chronic kidney disease (CKD) are prone to develop cardiovascular disorders. Numerous reports have shown the association between uremia and oxidative stress, which increases patients' risk for cumulative injury to multiple organs. Anemia is a common and disabling feature of CKD and seems to be a main cause of oxidative stress; correction of anemia represents an effective approach to reduce oxidative stress and, consequently, cardiovascular risk. There is increasing evidence that correction of anemia with erythropoiesis-stimulating agents could protect from oxidative stress in patients with CKD and ESRD. However, iron deficiency frequently complicates anemia in patients with CKD, and ferrous iron cation is a co-factor that is needed for hydroxyl radical production, which can promote cytotoxicity and tissue injury. This has raised a justifiable concern that prescription of intravenous iron may exacerbate oxidative stress and, hence, endothelial dysfunction, inflammation, and progression of cardiovascular disease, which are widely known consequences of CKD. Correction of anemia represents an effective approach to reduce oxidative stress and, consequently, cardiovascular risk. Iron deficiency is a common cause of resistance to erythropoiesis-stimulating agents, and the overall risk-benefit ratio favors use of intravenous iron to treat iron deficiency in patients with CKD. Consecutive or combined treatment with intravenous iron and erythropoiesis-stimulating agents clearly is beneficial for patients with CKD and iron deficiency, and anemia and could contribute to prevent the risk for cardiovascular events in these patients.

Assessment of inflammatory markers and endothelial function

PURPOSE OF REVIEW

To describe the background and assessment of inflammatory markers and endothelial function in atherosclerosis.

RECENT FINDINGS

Recent observations have related several inflammation markers, including cytokines and chemokines, soluble adhesion molecules, and acute-phase reactants, to the pathophysiology of atherosclerosis. Chronic inflammatory states such as rheumatoid arthritis and systemic lupus erythematosus have been identified as independent risk factors for early atherosclerosis. The role of endothelial function in atherosclerosis has been elucidated by clinical studies that have demonstrated that the status of vascular endothelium may modify the effects of risk factors on the development of atherosclerosis. These observations support the response-to-injury theory of atherosclerosis that emphasizes the role of endothelium in atherosclerosis.

SUMMARY

Inflammation and endothelial function play significant roles in the pathogenesis of atherosclerosis. Elevations in certain inflammatory mediators as well as evidence of endothelial dysfunction are related to increased risk of future cardiovascular morbidity. The value of measuring inflammatory markers and endothelial function in clinical practice remains to be defined.

Lipopolysaccharide regulated protein expression is only partly impaired in monocytes from patients with type I diabetes

BACKGROUND

Monocytes play an important role in innate immunity and atherosclerosis. A disturbed secretion of cytokines in lipopolysaccharide (LPS) activated monocytes from type 1 diabetes (T1D) patients has been described and may contribute to the impaired inflammatory response in these individuals. In the present study the influence of LPS on five different proteins with a function in immunity and atherosclerosis was analyzed in monocytes from controls and T1D patients.

METHODS

Monocytes were isolated from controls and T1D patients and the LPS-stimulated increase of IL-6, CXCL8, monocyte chemotactic protein 1 (CCL2, MCP-1) and superoxide dismutase (SOD 2), as well as the LPS-mediated decrease of apolipoprotein E (Apo E) in primary human monocytes from controls and T1D patients was determined.

RESULTS

CCL2 and IL-6 secretion in response to LPS was found significantly reduced in monocytes from T1D patients when compared to controls whereas basal CCL2 release was similar in control and T1D cells. In contrast, CXCL8 and apolipoprotein E secretion and SOD 2 expression upon LPS stimulation is similar from T1D and control monocytes.

CONCLUSION

These data indicate that LPS-mediated protein expression is only partly disturbed in monocytes from T1D patients. Reduced secretion of IL-6 and CCL2 in activated monocytes of these patients may contribute to an impaired inflammatory response and vascular disease.