Superoxide dismutase and catalase inhibit oxidized low-density lipoprotein-induced human aortic smooth muscle cell proliferation: Role of cell-cycle regulation, mitogen-activated protein kinases, and transcription factors

Effects of PM2.5 exposure on clock gene BMAL1 and cell cycle in human umbilical vein endothelial cells

Background

Fine particulate matter (PM2.5) exposure has been closely associated with cardiovascular diseases, which are relevant to cell cycle arrest. Brain and muscle aryl-hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) not only participates in regulating the circadian clock but also plays a role in modulating cell cycle. However, the precise contribution of the circadian clock gene BMAL1 to PM2.5-induced cell cycle change remains unclear. This study aims to explore the impact of PM2.5 exposure on BMAL1 expression and the cell cycle in human umbilical vein endothelial cells (HUVECs).

Methods

HUVECs was exposed to PM2.5 for 24 hours at different concentrations ((0, 12.5, 25, 75 and 100 μg.mL-1) to elucidate the potential toxic mechanism. Following exposure to PM2.5, cell viability, ROS, cell cycle, and the expression of key genes and proteins were detected.

Results

A remarkable decrease in cell viability is observed in the PM2.5-exposed HUVECs, as well as a significant increase in ROS production. In addition, PM2.5-exposed HUVECs have cycle arrest in G0/G1 phase, and the gene expression of p27 is also markedly increased. The protein expression of BMAL1 and the gene expression of BMAL1 are increased significantly. Moreover, the protein expressions of p-p38 MAPK and p-ERK1/2 exhibit a marked increase in the PM2.5-exposed HUVECs. Furthermore, following the transfection of HUVECs with siBMAL1 to suppress BMAL1 expression, we observed a reduction in both the protein and gene expression of the MAPK/ERK pathway in HUVECs exposed to PM2.5.

Conclusions

Overall, our results indicate that PM2.5 exposure significantly upregulates the circadian clock gene expression of BMAL1 and regulates G0/G1 cell cycle arrest in HUVECs through the MAPK/ERK pathway, which may provide new insights into the potential molecular mechanism regarding BMAL1 on PM2.5-induced cardiovascular diseases.

The serotonergic system dysfunction in diabetes mellitus

Most peripheral serotonin (5-HT) is synthesized in enterochromaffin cells, and most circulating 5-HT is stored in platelets. As a monoamine, 5-HT has several functions in various non-neuronal and neuronal systems. In the central nervous system, it functions as a neurotransmitter to modulate feeding behavior and mood. Numerous clinical trials have focused on increasing 5-HT activation in the central nervous system, including those involving anti-obesity drugs currently in the market, although severe side effects on peripheral system can lead to the withdrawal of certain drugs. Recent studies have revealed that both the peripheral and central serotonergic systems play a vital role in diabetes and its complications. This review summarizes the roles of the serotonergic system in blood glucose regulation, diabetic macroangiopathy, diabetic peripheral neuropathy, and diabetic encephalopathy, indicating its potential clinical significance as a therapeutic target for the treatment of diabetes and its complications.

Suppression of miR-4463 promotes phenotypic switching in VSMCs treated with Ox-LDL

Vascular smooth muscle cell (VSMC) phenotypic switching is a hallmark of vascular remodeling that contributes to atherosclerotic diseases. MicroRNA 4463 (miR-4463) has been implicated in the development of arteriosclerosis obliterans, whereas the underlying mechanisms in VSMCs have not been fully addressed. In this study, we assessed whether miR-4463 is involved in the phenotypic switching process in VSMCs. Oxidized low-density lipoprotein (Ox-LDL, 50 mg/L) was used to simulate the oxidative stress condition, and miR-4463 expression in VSMCs was detected by a quantitative polymerase chain reaction. To determine the effect of Ox-LDL-mediated regulation of miR-4463 on the phenotypic switching of VSMCs, cell counting kit-8, cell migration assays, and cytoskeleton test were performed. After using specific antagonists of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), the relationship between miR-4463 and its downstream signaling proteins was explored. Ox-LDL induced oxidative stress to promote VSMC transformation from contraction to secretion, which clearly decreased the level of miR-4463. Then, downregulated miR-4463 enhanced the migration and phenotypic transformation of VSMCs and activated the phosphorylation of JNK and ERK; these effects were increased after Ox-LDL induction. As expected, inhibiting the two signaling proteins blocked the effect of the miR-4463 inhibitor combined with Ox-LDL. In addition, inhibition of miR-4463 led to the upregulation of basic fibroblast growth factor (bFGF) expression. The results of this study demonstrate that miR-4463 is a novel regulator of VSMC function in hypoxic conditions and modulates VSMC phenotypic switching via the JNK and ERK signaling pathways; bFGF may be the target gene of miR-4463.

Catalase prevents myeloperoxidase self-destruction in response to oxidative stress

Catalase (CAT) and myeloperoxiase (MPO) are heme-containing enzymes that have attracted attention for their role in the etiology of numerous respiratory disorders such as cystic fibrosis, bronchial asthma, and acute hypoxemic respiratory failure. However, information regarding the interrelationship and competition between the two enzymes, free iron accumulation, and decreased levels of non-enzymatic antioxidants at sites of inflammation is still lacking. Myeloperoxidase catalyzes the generation of hypochlorous acid (HOCl) from the reaction of hydrogen peroxide (H₂O₂) and chloride (Cl^-). Self-generated HOCl has recently been proposed to auto-inhibit MPO through a mechanism that involves MPO heme destruction. Here, we investigate the interplay of MPO, HOCl, and CAT during catalysis, and explore the crucial role of MPO inhibitors and HOCl scavengers in protecting the catalytic site from protein modification of both enzymes against oxidative damage mediated by HOCl. We showed that CAT not only competes with MPO for H₂O₂ but also scavenges HOCl. The protective role provided by CAT versus the damaging effect provided by HOCl depends in part on the ratio between MPO/CAT and the affinity of the enzymes towards H₂O₂ versus HOCl. The severity of such damaging effects mainly depends on the ratio of HOCl to enzyme heme content. In addition to its effect in mediating protein modification and aggregation, HOCl oxidatively destroys the catalytic sites of the enzymes, which contain porphyrin rings and iron. Thus, modulation of MPO/CAT activities may be a fundamental feature of catalysis, and functions to down-regulate HOCl synthesis and prevent hemoprotein heme destruction and/or protein modification.

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

SIGNIFICANCE

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

CRITICAL ISSUES

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

FUTURE DIRECTIONS

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

Oxidative Stress in Aortas of Patients with Advanced Occlusive and Aneurysmal Diseases

BACKGROUND

Aortoiliac occlusive disease (AOD) and abdominal aortic aneurysm (AAA) are very important cardiovascular diseases that present different aspects of pathophysiology; however, oxidative stress and inflammatory response seem be relevant in both of them. Our objective was to evaluate oxidative damage and degree of inflammatory infiltrate in aortas of patients surgically treated for AOD and AAA.

MATERIALS AND METHODS

Levels of reactive oxygen species (ROS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, and myeloperoxidase (MPO) expression as well as nitrite levels and superoxide dismutase (SOD) and catalase (CAT) activities were evaluated in aortas of patients with AOD (n = 16) or AAA (n = 14), while the control group was formed by cadaveric organ donors (n = 10). We also analyzed the degree of inflammatory infiltrate in these aortas.

RESULTS

There was an increase in ROS levels and NADPH oxidase activity in patients with AOD and AAA when compared with the control group, and the AOD group demonstrated higher ROS production and NADPH oxidase activity and also nitrite levels when compared with the AAA group (P < 0.001). On the other hand, an increase of SOD activity in the AOD group and CAT activity in the AAA group was observed. Inflammatory infiltrate and MPO expression were higher in the AOD group when compared with the control group (P < 0.05).

CONCLUSIONS

Oxidative stress is relevant in both AOD and AAA, though AOD presented higher ROS levels and NADPH activity. Increased activities of antioxidant enzymes may be a compensatory phenomenon which occurs in aortas of patients with AOD and AAA. Perhaps, a relationship between oxidative stress and degree of inflammatory infiltrate may exist in the pathophysiology of AOD and AAA.

Effects of Atorvastatin on Oxidative Stress Biomarkers and Mitochondrial Morphofunctionality in Hyperfibrinogenemia-Induced Atherogenesis

Relationship between hyperfibrinogenemia (HF), oxidative stress, and atherogenesis was established. Effect of atorvastatin (Ator) was assessed. Wistar male (6 months) rats were studied: Ctr, control, without HF induction; Ctr-Ator, without HF treated with atorvastatin; AI, atherogenesis induced, and AI-Ator, atherogenesis induced and treated with atorvastatin. Atherogenesis was induced by daily adrenaline injection (0.1 mL/day/rat) for 90 days; treatment started 15 days after induction. Fibrinogen (mg/dL) and nitric oxide (NO) were measured in plasma (mM) and superoxide dismutase (SOD) (U/mL) in red cell lysate by spectrophotometry. Slices of aorta were analyzed by electron microscopy (EM). ANOVA and chi-square test were used; P < 0.05 was established. There were no significant differences between Ctr and Ctr-Atorv in fibrinogen, NO, and SOD values. Comparing Ctr with AI an increase of fibrinogen is observed (P < 0.001), but it decreased after administration of atorvastatin in AI-Ator (P < 0.001). NO diminished in AI relative to Ctr and increased in AI-Ator (P < 0.001). SOD showed an increase in AI and AI-Ator compared to Ctr (P < 0.001). EM revealed expansion of intermembrane space and disorganization of crests in AI. In AI-Ator mitochondrial areas and diameters were similar to control. Atorvastatin normalizes HF, stabilizes NO, increases SOD, and produces a partial regression of mitochondrial lesions.

Manganese superoxide dismutase regulates a redox cycle within the cell cycle

SIGNIFICANCE

Manganese superoxide dismutase (MnSOD) is a nuclear-encoded and mitochondria-matrix-localized oxidation-reduction (redox) enzyme that regulates cellular redox homeostasis. Cellular redox processes are known to regulate proliferative and quiescent growth states. Therefore, MnSOD and mitochondria-generated reactive oxygen species (ROS) are believed to be critical regulators of quiescent cells' entry into the cell cycle and exit from the proliferative cycle back to the quiescent state.

RECENT ADVANCES/CRITICAL ISSUES

Recent evidence suggests that the intracellular redox environment fluctuates during the cell cycle, shifting toward a more oxidized status during mitosis. MnSOD activity is higher in G0/G1 cells compared with S, G2 and M phases. After cell division, MnSOD activity increases in the G1 phase of the daughter generation. The periodic fluctuation in MnSOD activity during the cell cycle inversely correlates with cellular superoxide levels as well as glucose and oxygen consumption. Based on an inverse correlation between MnSOD activity and glucose consumption during the cell cycle, it is proposed that MnSOD is a central molecular player for the "Warburg effect."

FUTURE DIRECTIONS

In general, loss of MnSOD activity results in aberrant proliferation. A better understanding of the MnSOD and mitochondrial ROS-dependent cell cycle processes may lead to novel approaches to overcome aberrant proliferation. Since ROS have both deleterious (pathological) and beneficial (physiological) effects, it is proposed that "eustress" should be used when discussing ROS processes that regulate normal physiological functions, while "oxidative stress" should be used to discuss the deleterious effects of ROS.

Targeted Drug Delivery to Endothelial Adhesion Molecules

Endothelial cells represent important targets for therapeutic and diagnostic interventions in many cardiovascular, pulmonary, neurological, inflammatory, and metabolic diseases. Targeted delivery of drugs (especially potent and labile biotherapeutics that require specific subcellular addressing) and imaging probes to endothelium holds promise to improve management of these maladies. In order to achieve this goal, drug cargoes or their carriers including liposomes and polymeric nanoparticles are chemically conjugated or fused using recombinant techniques with affinity ligands of endothelial surface molecules. Cell adhesion molecules, constitutively expressed on the endothelial surface and exposed on the surface of pathologically altered endothelium—selectins, VCAM-1, PECAM-1, and ICAM-1—represent good determinants for such a delivery. In particular, PECAM-1 and ICAM-1 meet criteria of accessibility, safety, and relevance to the (patho)physiological context of treatment of inflammation, ischemia, and thrombosis and offer a unique combination of targeting options including surface anchoring as well as intra- and transcellular targeting, modulated by parameters of the design of drug delivery system and local biological factors including flow and endothelial phenotype. This review includes analysis of these factors and examples of targeting selected classes of therapeutics showing promising results in animal studies, supporting translational potential of these interventions.

Antioxidant enzymes as potential targets in cardioprotection and treatment of cardiovascular diseases. Enzyme antioxidants: the next stage of pharmacological counterwork to the oxidative stress

The focus in antioxidant research is on enzyme derivative investigations. Extracellular superoxide dismutase (EC-SOD) is of particular interest, as it demonstrates in vivo the protective action against development of atherosclerosis, hypertension, heart failure, diabetes mellitus. The reliable association of coronary artery disease with decreased level of heparin-released EC-SOD was established in clinical research. To create a base for and to develop antioxidant therapy, various SOD isozymes, catalase (CAT), methods of gene therapy, and combined applications of enzymes are used. Covalent bienzyme SOD-CHS-CAT conjugate (CHS, chondroitin sulphate) showed high efficacy and safety as the drug candidate. There is an evident trend to use the components of glycocalyx and extra-cellular matrix for target delivery of medical substances. Development of new enzyme antioxidants for therapeutic application is closely connected with progress in medical biotechnology, the pharmaceutical industry, and the bioeconomy.

Differential suppression of intracellular reactive oxygen species-mediated signaling pathway in vascular endothelial cells by several subclasses of flavonoids

Increased intracellular reactive oxygen species (ROS) is crucial for vascular endothelial dysfunction, a key step in the initiating of atherosclerosis (AS). The antioxidant activity of flavonoids has been suggested to contribute to AS prevention. However, The association of the structure characteristics to antioxidant capacities in relation to the inhibitory effects on endothelial dysfunction has not been well established. In this study, four subclasses of flavonoids with similar structures, including two anthocyanins (delphinidin and cyanidin), two flavonols (myricetin and quercetin), two flavones (luteolin and apigenin) and two isoflavones (genistein and daidzein) were examined for their inhibitory effects on intracellular ROS-mediated signaling pathway in the human umbilical vein endothelial cell EA.hy926. Cells were pretreated with different flavonoids for 2 h and then exposed to oxLDL of 100 μg/ml for another 24 h. It was found that treatment with different flavonoids alone had no notable effects on cell viability. However, the oxLDL-induced decrease of cell viability, generation of O(2)(·-) and ROS, p38MAPK activation, NF-κB nuclear translocation, NF-κB-modulated transcriptional activity as well as the mRNA expression of genes including ICAM-1, VCAM-1, E-selectin, MMP-1, MMP-2 and MMP-9 were notably inhibited by the pretreatment of different flavonoids through blunting ROS-triggered signaling pathway, in spite of apparent differences. And the number of hydroxyl groups in total, 3',4'-ortho-dihydroxyl in B-ring and 3-hydroxyl group in C-ring of flavonoids were important structure characteristics for the inhibitory effects. Thus, anthocyanins and flavonols such as delphinidin and myricetin exert higher ROS scavenging activities and more significant endothelium-protective effects compared to the other compounds. Our results provide evidence for AS prevention and a basis for designing the potent anti-atherosclerotic agents.

Antiatherosclerotic Effect of an Antibody That Binds to Extracellular Matrix Glycosaminoglycans

Objective—

Subendothelial retention of proatherogenic lipoproteins by proteoglycans is critical in atherosclerosis. The aim of this study was to characterize the recognition and antiatherogenic properties of a chimeric monoclonal antibody (mAb) that reacts with sulfated molecules.

Methods and Results—

chP3R99 mAb recognized sulfated glycosaminoglycans, mainly chondroitin sulfate (CS), by ELISA. This mAb blocked ≈70% of low-density lipoprotein (LDL)–CS association and ≈80% of LDL oxidation in vitro, and when intravenously injected to Sprague-Dawley rats (n=6, 1 mg/animal), it inhibited LDL (4 mg/kg intraperitoneally, 1 hour later) retention and oxidation in the artery wall. Moreover, subcutaneous immunization of New Zealand White rabbits (n=19) with chP3R99 mAb (100 μg, 3 doses at weekly intervals) prevented Lipofundin-induced atherosclerosis (2 mL/kg, 8 days) with a 22-fold reduction in the intima-media ratio ( P <0.01). Histopathologic and ultrastructural studies showed no intimal alterations or slight thickening, with preserved junctions between endothelial cells and scarce collagen fibers and glycosaminoglycans. In addition, immunization with chP3R99 mAb suppressed macrophage infiltration in aorta and preserved redox status. The atheroprotective effect was associated with the induction of anti-CS antibodies in chP3R99-immunized rabbits, capable of blocking CS-LDL binding and LDL oxidation.

Conclusion—

These results support the use of anti-sulfated glycosaminoglycan antibody–based immunotherapy as a potential tool to prevent atherosclerosis.

Targeted interception of signaling reactive oxygen species in the vascular endothelium

Reactive oxygen species (ROS) are implicated as injurious and as signaling agents in human maladies including inflammation, hyperoxia, ischemia-reperfusion and acute lung injury. ROS produced by the endothelium play an important role in vascular pathology. They quench, for example, nitric oxide, and mediate pro-inflammatory signaling. Antioxidant interventions targeted for the vascular endothelium may help to control these mechanisms. Animal studies have demonstrated superiority of targeting ROS-quenching enzymes catalase and superoxide dismutase to endothelial cells over nontargeted formulations. A diverse arsenal of targeted antioxidant formulations devised in the last decade shows promising results for specific quenching of endothelial ROS. In addition to alleviation of toxic effects of excessive ROS, these targeted interventions suppress pro-inflammatory mechanisms, including endothelial cytokine activation and barrier disruption. These interventions may prove useful in experimental biomedicine and, perhaps, in translational medicine.

The role of peroxidases in the pathogenesis of atherosclerosis

Reactive oxygen species (ROS), which include superoxide anions and peroxides, induce oxidative stress, contributing to the initiation and progression of cardiovascular diseases involving atherosclerosis. The endogenous and exogenous factors hypercholesterolemia, hyperglycemia, hypertension, and shear stress induce various enzyme systems such as nicotinamide adenine dinucleotide (phosphate) oxidase, xanthine oxidase, and lipoxygenase in vascular and immune cells, which generate ROS. Besides inducing oxidative stress, ROS mediate signaling pathways involved in monocyte adhesion and infiltration, platelet activation, and smooth muscle cell migration. A number of antioxidant enzymes (e.g., superoxide dismutases, catalase, glutathione peroxidases, and peroxiredoxins) regulate ROS in vascular and immune cells. Atherosclerosis results from a local imbalance between ROS production and these antioxidant enzymes. In this review, we will discuss 1) oxidative stress and atherosclerosis, 2) ROS-dependent atherogenic signaling in endothelial cells, macrophages, and vascular smooth muscle cells, 3) roles of peroxidases in atherosclerosis, and 4) antioxidant drugs and therapeutic perspectives.

Hydrogen-rich saline prevents neointima formation after carotid balloon injury by suppressing ROS and the TNF-α/NF-κB pathway

BACKGROUND

Reactive oxygen species (ROS) play a pivotal role in neointima hyperplasia after balloon injury. Molecular hydrogen has emerged as a novel antioxidant and has been proven effective in treating many diseases.

OBJECTIVES

We aimed to determine the mechanism by which hydrogen affects neointima formation.

METHODS

We assessed the influence of a hydrogen-rich saline solution (HRSS) by daily injection in rats. Rats were euthanized to evaluate the neointima. ROS, malondialdehyde (MDA) and superoxide dismutase (SOD) and reduced glutathione (GSH), were detected in the injured artery. Macrophage infiltration and the production of inflammatory factors (i.e., IL-6, TNF-α and NF-κB) were also observed. The in vitro effects of hydrogen on vascular smooth muscle cell (VSMC) proliferation were also measured.

RESULTS

HRSS decreased the neointima area significantly. The neointima/media ratio was also reduced by HRSS. There was a decline in the number of PCNA-positive cells in the intima treated with HRSS. Meanwhile, HRSS ameliorated the ROS and MDA levels and increased SOD, reduced GSH levels in the injured carotid. In addition, the levels of inflammatory factors, such as IL-6, TNF-α and NF-κB p65, were attenuated by HRSS. In vitro studies also confirmed the anti-proliferative capability of the hydrogen solution and ROS generation in VSMCs induced by PDGF-BB.

CONCLUSION

HRSS may have a protective role in the prevention of neointima hyperplasia and restenosis after angioplasty. HRSS may partially exert its role by neutralizing the local ROS and suppressing the TNF-α/NF-κB pathway.

Viscolin reduces VCAM-1 expression in TNF-α-treated endothelial cells via the JNK/NF-κB and ROS pathway

Viscolin, a major active component in a chloroform extract of Viscum coloratum, has antioxidative and anti-inflammatory properties. We focused on its effects on the expression of vascular cell adhesion molecule-1 (VCAM-1) in tumor necrosis factor-α (TNF-α)-treated human umbilical vein endothelial cells (HUVECs). The TNF-α-induced expression of VCAM-1 was significantly reduced by respectively 38±7 or 34±16% when HUVECs were pretreated with 10 or 30μM viscolin, as shown by Western blotting, and was also significantly reduced by pretreatment with the antioxidants N-acetylcysteine, diphenylene iodonium chloride, and apocynin. Viscolin also reduced TNF-α-induced VCAM-1 mRNA expression and promoter activity, decreased reactive oxygen species (ROS) production, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, and significantly reduced the binding of monocytes to TNF-α-stimulated HUVECs. The attenuation of TNF-α-induced VCAM-1 expression and cell adhesion was partly mediated by a decrease in JNK phosphorylation. Furthermore, viscolin reduced VCAM-1 expression in the aorta of TNF-α-treated mice in vivo. Taken together, these data show that viscolin inhibits TNF-α-induced JNK phosphorylation, nuclear translocation of NF-κB p65, and ROS generation and thereby suppresses VCAM-1 expression, resulting in reduced adhesion of leukocytes. These results also suggest that viscolin may prevent the development of atherosclerosis and inflammatory responses.

Lipofundin-induced hyperlipidemia promotes oxidative stress and atherosclerotic lesions in new zealand white rabbits

Atherosclerosis represents a major cause of death in the world. It is known that Lipofundin 20% induces atherosclerotic lesions in rabbits, but its effects on serum lipids behaviour and redox environment have not been addressed. In this study, New Zealand rabbits were treated with 2 mL/kg of Lipofundin for 8 days. Then, redox biomarkers and serum lipids were determined spectrophotometrically. On the other hand, the development of atherosclerotic lesions was confirmed by eosin/hematoxylin staining and electron microscopy. At the end of the experiment, total cholesterol, triglycerides, cholesterol-LDL, and cholesterol-HDL levels were significantly increased. Also, a high index of biomolecules damage, a disruption of both enzymatic and nonenzymatic defenses, and a reduction of nitric oxide were observed. Our data demonstrated that Lipofundin 20% induces hyperlipidemia, which promotes an oxidative stress state. Due to the importance of these phenomena as risk factors for atherogenesis, we suggest that Lipofundin induces atherosclerosis mainly through these mechanisms.

Peroxiredoxin 2 deficiency exacerbates atherosclerosis in apolipoprotein E-deficient mice

RATIONALE

Peroxiredoxin 2 (Prdx2), a thiol-specific peroxidase, has been reported to regulate proinflammatory responses, vascular remodeling, and global oxidative stress.

OBJECTIVE

Although Prdx2 has been proposed to retard atherosclerosis development, no direct evidence and mechanisms have been reported.

METHODS AND RESULTS

We show that Prdx2 is highly expressed in endothelial and immune cells in atherosclerotic lesions and blocked the increase of endogenous H(2)O(2) by atherogenic stimulation. Deficiency of Prdx2 in apolipoprotein E-deficient (ApoE(-/-)) mice accelerated plaque formation with enhanced activation of p65, c-Jun, JNKs, and p38 mitogen-activated protein kinase; and these proatherogenic effects of Prdx2 deficiency were rescued by administration of the antioxidant ebselen. In bone marrow transplantation experiments, we found that Prdx2 has a major role in inhibiting atherogenic responses in both vascular and immune cells. Prdx2 deficiency resulted in increased expression of vascular adhesion molecule-1, intercellular adhesion molecule-1, and monocyte chemotactic protein-1, which led to increased immune cell adhesion and infiltration into the aortic intima. Compared with deficiency of glutathione peroxidase 1 or catalase, Prdx2 deficiency showed a severe predisposition to develop atherosclerosis.

CONCLUSIONS

Prdx2 is a specific peroxidase that inhibits atherogenic responses in vascular and inflammatory cells, and specific activation of Prdx2 may be an effective means of antiatherogenic therapy.

Targeted modulation of reactive oxygen species in the vascular endothelium

'Endothelial cells lining vascular luminal surface represent an important site of signaling and injurious effects of reactive oxygen species (ROS) produced by other cells and endothelium itself in ischemia, inflammation and other pathological conditions. Targeted delivery of ROS modulating enzymes conjugated with antibodies to endothelial surface molecules (vascular immunotargeting) provides site-specific interventions in the endothelial ROS, unattainable by other formulations including PEG-modified enzymes. Targeting of ROS generating enzymes (e.g., glucose oxidase) provides ROS- and site-specific models of endothelial oxidative stress, whereas targeting of antioxidant enzymes SOD and catalase offers site-specific quenching of superoxide anion and H(2)O(2). These targeted antioxidant interventions help to clarify specific role of endothelial ROS in vascular and pulmonary pathologies and provide basis for design of targeted therapeutics for treatment of these pathologies. In particular, antibody/catalase conjugates alleviate acute lung ischemia/reperfusion injury, whereas antibody/SOD conjugates inhibit ROS-mediated vasoconstriction and inflammatory endothelial signaling. Encapsulation in protease-resistant, ROS-permeable carriers targeted to endothelium prolongs protective effects of antioxidant enzymes, further diversifying the means for targeted modulation of endothelial ROS.

Anti-atherogenic effect of berberine on LXRalpha-ABCA1-dependent cholesterol efflux in macrophages

Berberine, a botanical alkaloid purified from Cortidis rhizoma, has effects in cardiovascular diseases, yet the mechanism is not fully understood. Foam cells play a critical role in the progression of atherosclerosis. This study aimed to investigate the effect of berberine on the formation of foam cells by macrophages and the underlying mechanism. Treatment with berberine markedly suppressed oxidized low-density lipoprotein (oxLDL)-mediated lipid accumulation, which was due to an increase in cholesterol efflux. Berberine enhanced the mRNA and protein expression of ATP-binding membrane cassette transport protein A1 (ABCA1) but did not alter the protein level of ABCG1 or other scavenger receptors. Additionally, functional inhibition of ABCA1 with a pharmacological inhibitor or neutralizing antibody abrogated the effects of berberine on cholesterol efflux and lipid accumulation. Moreover, berberine induced the nuclear translocation and activation of liver X receptor alpha (LXRalpha) but not its protein expression. Knockdown of LXRalpha mRNA expression by small interfering RNA abolished the berberine-mediated protective effects on ABCA1 protein expression and oxLDL-induced lipid accumulation in macrophages. These data suggest that berberine abrogates the formation of foam cells by macrophages by enhancing LXRalpha-ABCA1-dependent cholesterol efflux.

Salvianolic acid B inhibits low-density lipoprotein oxidation and neointimal hyperplasia in endothelium-denuded hypercholesterolaemic rabbits

BACKGROUND

Atherosclerosis and restenosis are inflammatory responses involving free radicals and lipid peroxidation and may be prevented/cured by antioxidant-mediated lipid peroxidation inhibition. Salvianolic acid (Sal B), a water-soluble antioxidant obtained from a Chinese medicinal herb, is believed to have multiple preventive and therapeutic effects against human vascular diseases. In this study the in vitro and in vivo inhibitory effects of Sal B on oxidative stress were determined.

RESULTS

In human aortic endothelial cells (HAECs), Sal B reduced oxidative stress, inhibited low-density lipoprotein (LDL) oxidation and reduced oxidised LDL-induced cytotoxicity. Sal B inhibited Cu(2+) -induced LDL oxidation in vitro (with a potency 16.3 times that of probucol) and attenuated HAEC-mediated LDL oxidation as well as reactive oxygen species (ROS) production. In cholesterol-fed New Zealand White rabbits (with probucol as positive control), Sal B intake reduced Cu(2+) -induced LDL oxidation, lipid deposition in the thoracic aorta, intimal thickness of the aortic arch and thoracic aorta and neointimal formation in the abdominal aorta.

CONCLUSION

The data obtained in this study suggest that Sal B protects HAECs from oxidative injury-mediated cell death via inhibition of ROS production. The antioxidant activity of Sal B may help explain its efficacy in the treatment of vascular diseases.

TGF-β regulates Nox4, MnSOD and catalase expression, and IL-6 release in airway smooth muscle cells

Reactive oxygen species (ROS) are generated as a result of normal cellular metabolism, mainly through the mitochondria and peroxisomes, but their release is enhanced by the activation of oxidant enzymes such as NADPH oxidases or downregulation of endogenous antioxidant enzymes such as manganese-superoxide dismutase (MnSOD) and catalase. Transforming growth factor-β (TGF-β), found to be overexpressed in airway smooth muscle (ASM) from asthmatic and chronic obstructive pulmonary disease patients, may be a pivotal regulator of abnormal ASM cell (ASMC) function in these diseases. An important effect of TGF-β on ASMC inflammatory responses is the induction of IL-6 release. TGF-β also triggers intracellular ROS release in ASMCs by upregulation of NADPH oxidase 4 (Nox4). However, the effect of TGF-β on the expression of key antioxidant enzymes and subsequently on oxidant/antioxidant balance is unknown. Moreover, the role of redox-dependent pathways in the mediation of the proinflammatory effects of TGF-β in ASMCs is unclear. In this study, we show that TGF-β induced the expression of Nox4 while at the same time inhibiting the expression of MnSOD and catalase. This change in oxidant/antioxidant enzymes was accompanied by elevated ROS levels and IL-6 release. Further studies revealed a role for Smad3 and phosphatidyl-inositol kinase-mediated pathways in the induction of oxidant/antioxidant imbalance and IL-6 release. The changes in oxidant/antioxidant enzymes and IL-6 release were reversed by the antioxidants N-acetyl-cysteine (NAC) and ebselen through inhibition of Smad3 phosphorylation, indicating redox-dependent activation of Smad3 by TGF-β. Moreover, these findings suggest a potential role for NAC in preventing TGF-β-mediated pro-oxidant and proinflammatory responses in ASMCs. Knockdown of Nox4 using small interfering RNA partially prevented the inhibition of MnSOD but had no effect on catalase and IL-6 expression. These findings provide novel insights into redox regulation of ASM function by TGF-β.

PECAM-targeted delivery of SOD inhibits endothelial inflammatory response

Elevated generation of reactive oxygen species (ROS) by endothelial enzymes, including NADPH-oxidase, is implicated in vascular oxidative stress and endothelial proinflammatory activation involving exposure of vascular cell adhesion molecule-1 (VCAM-1). Catalase and superoxide dismutase (SOD) conjugated with antibodies to platelet/endothelial cell adhesion molecule 1 (PECAM-1) bind specifically to endothelium and inhibit effects of corresponding ROS, H(2)O(2), and superoxide anion. In this study, anti-PECAM/SOD, but not anti-PECAM/catalase or nontargeted enzymes, including polyethylene glycol (PEG)-SOD, inhibited 2- to 3-fold VCAM expression caused by tumor necrosis factor (TNF), interleukin-1β, and lipopolysaccharide. Anti- PECAM/SOD, but not nontargeted counterparts, accumulated in vascular endothelium after intravenous injection, localized in endothelial endosomes, and inhibited by 70% lipopolysaccharide-caused VCAM-1 expression in mice. Anti-PECAM/SOD colocalized with EEA-1-positive endothelial vesicles and quenched ROS produced in response to TNF. Inhibitors of NADPH oxidase and anion channel ClC3 blocked TNF-induced VCAM expression, affirming that superoxide produced and transported by these proteins, respectively, mediates inflammatory signaling. Anti-PECAM/SOD abolished VCAM expression caused by poly(I:C)-induced activation of toll-like receptor 3 localized in intracellular vesicles. These results directly implicate endosomal influx of superoxide in endothelial inflammatory response and suggest that site-specific interception of this signal attained by targeted delivery of anti-PECAM/SOD into endothelial endosomes may have anti-inflammatory effects.

CREB downregulation in vascular disease: a common response to cardiovascular risk

OBJECTIVE

To examine the impact of low-density lipoprotein (LDL), an established mediator of atherosclerosis, on the transcription factor cAMP-response element-binding protein (CREB), which is a regulator of vascular smooth muscle cell (VSMC) quiescence.

METHODS AND RESULTS

VSMC CREB content is diminished in rodent models of diabetes and pulmonary hypertension. We examined aortic CREB content in rodent models of aging, hypertension, and insulin resistance, and we determined nuclear CREB protein in the medial VSMC of high-fat-fed LDL receptor-null mice. There was significant loss of CREB protein in all models. In vitro, primary culture rat aortic VSMC exposed to LDL and oxidized LDL exhibited a rapid, transient increase in CREB phosphorylation and transient phosphorylation/activation of Akt, ERK, JNK, ans p38 MAPK. Exposure to oxidized LDL, but not to LDL, for 24 to 48 hours decreased CREB protein in a dose-dependent fashion and led to nuclear exclusion of CREB. Pharmacological reactive oxygen species scavengers and inhibition of ERK activation blocked oxidized LDL-mediated CREB downregulation.

CONCLUSIONS

These data support a model wherein loss of VSMC CREB protein, which renders these cells more susceptible to activation and apoptosis, is a common pathological response to vascular injury and potentially contributes to plaque progression.

Intestinal Lactobacillus sp. is associated with some cellular and metabolic characteristics of blood in elderly people

The higher counts or particular groups (Firmicutes/Bacteroidetes) of intestinal microbiota are related to host metabolic reactions, supporting a balance of human ecosystem. We further explored whether intestinal lactobacilli were associated with some principal cellular and metabolic markers of blood in 38 healthy >65-year-old persons. The questionnaire, routine clinical and laboratory data of blood indices as much as the oxidized low-density lipoprotein (ox-LDL) and baseline diene conjugates in low-density lipoprotein (BDC-LDL) of blood sera were explored. The PCR-based intestinal Lactobacillus sp. composition and counts of cultivable lactobacilli (LAB) were tested. The facultative heterofermentative lactobacilli (Lactobacillus casei and Lactobacillus paracasei) were the most frequent (89 and 97%, respectively) species found, while Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus reuteri were present in almost half of the elderly persons. The number of species simultaneously colonizing the individuals ranged from 1 to 7 (median 4). In elderly consuming probiotics the LAB counts were significantly higher than in these not consuming (median 7.8, range 4.2-10.8 vs. median 6.3, range 3.3-9.7 log cfu/g; p=0.005), adjusted (OR=1.71, CI95 1.04-2.82; p=0.035) for age and body mass index (BMI). The colonization by L. acidophilus was negatively related (r=-0.367, p=0.0275) to L. reuteri, staying significant after adjusting for age, sex and BMI (OR=0.16, CI95 0.04-0.73; p=0.018). However, the blood glucose concentration showed a tendency for a negative correlation for colonization with Lactobacillus fermentum (r=-0.309, p=0.062) adjusted for BMI (Adj. R(2)=0.181; p=0.013) but not for age and sex. The higher white blood cells (WBC) count was positively related (r=0.434, p=0.007) to presence of Lactobacillus reuteri adjusted for age, sex and BMI (Adj. R(2)=0.193, p=0.027). The lower values of ox-LDL were predicted by higher counts of cultivable lactobacilli adjusted by sex, age and BMI (r = -0.389, p = 0.016; Adj. R(2)=0.184 p=0.029). In conclusion, the pilot study of elderly persons shows that the intestinal lactobacilli are tightly associated with WBC count, blood glucose and content of ox-LDL which all serve as risk markers in pathogenesis of inflammation, metabolic syndrome and cardiovascular disease (CVD).

Overexpression of catalase delays G0/G1- to S-phase transition during cell cycle progression in mouse aortic endothelial cells

Although it is understood that hydrogen peroxide (H(2)O(2)) promotes cellular proliferation, little is known about its role in endothelial cell cycle progression. To assess the regulatory role of endogenously produced H(2)O(2) in cell cycle progression, we studied the cell cycle progression in mouse aortic endothelial cells (MAECs) obtained from mice overexpressing a human catalase transgene (hCatTg), which destroys H(2)O(2). The hCatTg MAECs displayed a prolonged doubling time compared to wild-type controls (44.0 +/- 4.7 h versus 28.6 +/- 0.8 h, p<0.05), consistent with a diminished growth rate and H(2)O(2) release. Incubation with aminotriazole, a catalase inhibitor, prevented the observed diminished growth rate in hCatTg MAECs. Inhibition of catalase activity with aminotriazole abrogated catalase overexpression-induced antiproliferative action. Flow cytometry analysis indicated that the prolonged doubling time was principally due to an extended G(0)/G(1) phase in hCatTg MAECs compared to the wild-type cells (25.0 +/- 0.9 h versus 15.9 +/- 1.4 h, p< 0.05). The hCatTg MAECs also exhibited decreased activities of the cyclin-dependent kinase (Cdk) complexes responsible for G(0)/G(1)- to S-phase transition in the cell cycle, including the cyclin D-Cdk4 and cyclin E-Cdk2 complexes. Moreover, the reduction in cyclin-Cdk activities in hCatTg MAECs was accompanied by increased protein levels of two Cdk inhibitors, p21 and p27, which inhibit the Cdk activity required for the G(0)/G(1)- to S-phase transition. Knockdown of p21 and/or p27 attenuated the antiproliferative effect of catalase overexpression in MAECs. These results, together with the fact that catalase is an H(2)O(2) scavenger, suggest that endogenously produced H(2)O(2) mediates MAEC proliferation by fostering the transition from G(0)/G(1) to S phase.

Blockade of oxidized LDL-triggered endothelial apoptosis by quercetin and rutin through differential signaling pathways involving JAK2

Oxidized LDL is highly atherogenic, as it stimulates foam cell formation and promotes inflammatory and thrombotic processes. The present study elucidated whether the antioxidants quercetin and its rutinoside rutin exert antiapoptosis in endothelial cells exposed to Cu(2+)-oxidized LDL. Quercetin and rutin inhibited the oxidized LDL-induced endothelial toxicity at nontoxic doses of </=25 muM with an inhibition of intracellular oxidant accumulation. These effects accompanied disappearance of apoptotic bodies and suppression of caspase-3 activation. Additionally, condensed nuclei vanished in oxidized LDL-exposed cells treated with quercetin and rutin. This study further explored whether such effects were achieved by redox manipulation via JAK2-STAT3-responsive death/survival signaling pathways involving multiple MAPK. Unlike quercetin, rutin blocked the activation of oxidized LDL-induced JNK and p38 MAPK as well as the upstream ASK1 phosphorylation. Quercetin dose-dependently attenuated the JAK2 phosphorylation evoked by oxidized LDL, whereas rutin abolished the JAK signaling accompanying nuclear transactivation of STAT3 and enhanced the JAK activity-inhibiting SOCS3 expression. Conversely, oxidized LDL-induced IL-6 release was minimal for the JAK2 activation, although this effect was counteracted by quercetin and rutin. These results suggest that quercetin and rutin inhibit Cu(2+)-oxidized LDL-induced endothelial apoptosis through modulating JAK2-STAT3 pathways and that rutin may modulate a signaling crosstalk between JAK2 and MAPK.

Effects of different LDL particles on inflammatory molecules in human mesangial cells

AIMS/HYPOTHESIS

Inflammation is a mechanism of glomerular damage in chronic glomerulopathies. LDL may increase the production of inflammatory cytokines in renal tissues. However, the relative role of native, oxidised and glycated LDL in promoting this process has been only partially elucidated.

METHODS

We tested the inflammatory and proapoptotic effects of native, oxidised and glycated LDL in human mesangial cells (HMCs) by measuring levels of IL6, CD40 and macrophage migration inhibitory factor (MIF) genes, MIF protein, release of IL6, soluble CD40, fibronectin and laminin, early and late apoptosis, and extracellular regulated kinases (ERK) 1/2 and c-Jun N-terminal kinase (JNK) activation.

RESULTS

IL6 and CD40 mRNA were dose-dependently upregulated by all three species; this was closely paralleled by their increased release. MIF mRNA was potently stimulated by modified LDL, as confirmed by immunostaining. Fibronectin and laminin release was stimulated by both oxidised and glycated, but not native, LDL. All LDL species induced some increase in late, but not early, apoptosis, and similarly activated JNK2/3 phosphorylation; in contrast, ERK1/2 phosphorylation was more strongly upregulated by oxidised than either native or glycated LDL.

CONCLUSIONS

In HMCs, the production and release of IL6 and CD40 is stimulated by both native and modified LDL, while MIF is more strongly stimulated by oxidised LDL. Regarding the pattern of mesangial expansion, fibronectin and laminin are upregulated by oxidised and glycated LDL. Apoptosis, if modest, is induced by all species. Intracellular signalling of native and modified LDL involves JNK2/3 and, perhaps more specifically, ERK1/2. Tight control of the lipid profile may be useful in preserving kidney function in patients with metabolic alterations.

Dietary flavonoids differentially reduce oxidized LDL-induced apoptosis in human endothelial cells: role of MAPK- and JAK/STAT-signaling

Endothelial apoptosis is a driving force in atherosclerosis development. Oxidized LDL promotes inflammatory and thrombotic processes and is highly atherogenic, as it stimulates macrophage cholesterol accumulation and foam cell formation. This study investigated multiple mitogen-activated protein kinase (MAPK)-responsive death/survival signaling pathways, through which flavonoids of (-)epigallocatechin gallate (EGCG) and hesperetin exerted antiapoptosis in endothelial cells exposed to oxidized LDL. EGCG and hesperetin substantially diminished the oxidized LDL-induced 2',7'-dichlorofluorecein staining, suggesting that these flavonoids inhibited intracellular accumulation of oxidized LDL-triggered reactive oxygen species and consequent apoptosis. The Western-blot data revealed that oxidized LDL upregulated c-Jun N-terminal kinase (JNK) phosphorylation, which was rapidly reversed by EGCG and hesperetin. They mitigated the consequent activation of the JNK downstream on p53 and c-Jun. Moreover, oxidized LDL increased luciferase activity of p53 in endothelial cells transfected with a p53 promoter construct, the increase of which was strikingly downregulated by EGCG and hesperetin. Surprisingly, hesperetin but not EGCG attenuated phosphorylation of p38MAPK and its downstream c-myc and signal transducers and activators of transcription (STAT)1 evoked by oxidized LDL. This study also attempted to explore a linkage of Janus kinase (JAK)2/STAT3 activation to MAPK signaling in oxidized LDL-induced endothelial apoptosis. Notably, we found that the JAK2 inhibitor substantially blocked the JNK activation. Our findings suggest that EGCG and hesperetin may act as antiatherogenic agents blocking oxidized LDL-induced endothelial apoptosis via differential cellular apoptotic machinery. These data provide evidence that the interplay between p38MAPK and JAK-STAT pathways is involved in dietary flavonoid protection against oxidized LDL through hampering MAPK-dependent pathways involving the activation of JAK2.

Age-dependent dichotomous effect of superoxide dismutase Ala16Val polymorphism on oxidized LDL levels

We investigated the association between superoxide dismutase (SOD) Ala16Val polymorphism and the levels of oxidized LDL lipoprotein-C (ox-LDL-C) in two age-different Greek cohorts. Four hundred fifteen middle-aged (n=147 females: 43.2+/-13 years, n=268 males: 43.3+/-14 years) Caucasian Greek subjects consisted the middle aged cohort. One hundred seventy five elderly (n=88 females: 79.9+/-4 years; n=87 males: 80.6+/-4 years) were selected from the elderly cohort. Genotype data were obtained for all of them. Multiple linear regression analysis, stratified by gender and adjusted for age, smoking habits and body mass index as covariates, showed higher ox-LDL-C levels for the middle aged men with the Val/Val genotype, compared to the other allele (Ala/Ala and Ala/Val) carriers (65.9+/-25.7 vs. 55.7+/-20.5 mg/dl; standardized beta coefficient=0.192, P=0.012). On the contrary, elderly women with the Val/Val genotype occurred with lower ox-LDL-C levels compared to the Ala/Ala or Ala/Val genotype (74.2+/-22.1 vs. 86.5+/-26.6 mg/dl; standardized beta coefficient= -0.269, P=0.015). The same trend was also recorded in elderly men, however without reaching statistical significance (standardized beta coefficient= -0.187, P=0.077). Moreover, elderly men and women with the Ala/Ala or Ala/Val genotype presented higher triglycerides levels compared to Val/Val (women: 145.2+/-68.7 vs. 114.3+/- 34.3 mg/dl, P= 0.027; men: 147.8+/-72.4 vs. 103.7 +/-38.0 mg/dl, P=0.002). Additionally, middle aged men with the Val/Val genotype had higher HDL-C levels compared to the Ala allele carriers. The results suggest that SOD Ala16Val polymorphism is an age-dependent modulator of ox-LDL-C levels in middle-aged men and elderly women.

CuZn-SOD suppresses the bovine papillomavirus-induced proliferation of fibroblasts

Eukaryotic cells continuously produce reactive oxygen species (ROS) and have mechanisms to control ROS levels. ROS have been shown to mediate cell proliferation and transformation. We studied the effect of CuZn-superoxide dismutase (CuZnSOD) on the focus-forming ability of bovine papillomavirus (BPV-1) wtDNA and hypertransforming mutant of its major oncoprotein E5, E5-17S. We found that CuZnSOD suppresses the focus-forming ability of BPV-1 wtDNA and E5 oncoprotein. Significantly fewer foci were detected in pCGCuZnSOD- and BPV-1 DNA-cotransfected cell culture compare to BPV-1 DNA-transfected cell culture (p<0.001). CuZnSOD decreases the rate of cell proliferation in both non-transformed C127 and BPV-1- and E5-transformed cell lines. CuZnSOD decelerates cell entry into the S phase of the cell cycle and has a suppressing effect on the actively dividing cells. As the transformed cells proliferate faster than normal cells when confluent, CuZnSOD inhibits the growth of foci. These results indicate that superoxide radicals may be involved in signaling for cell proliferation and that SOD suppresses cell proliferation.

Magnesium tanshinoate B protects endothelial cells against oxidized lipoprotein-induced apoptosisThis article is one of a selection of papers published in this special issue (part 2 of 2) on the Safety and Efficacy of Natural Health Products

The activation of c-Jun N-terminal kinase (JNK) signaling pathway plays an important role in the induction of cell apoptosis. We previously reported that magnesium tanshinoate B (MTB), a compound purified from a Chinese herb danshen ( Salvia miltiorrhiza ), could inhibit ischemia/reperfusion-induced myocyte apoptosis in the heart. The objective of the present study was to investigate whether MTB can prevent oxidized lipoprotein-induced apoptosis in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were incubated with copper-oxidized very low density lipoprotein (Cu-OxVLDL) or copper-oxidized low density lipoprotein (Cu-OxLDL). Treatment of cells with Cu-OxVLDL or Cu-OxLDL resulted in a 3-fold increase in the JNK activity. The amount of cytochrome c released and the activity of caspase-3 in cells treated with Cu-OxVLDL or Cu-OxLDL were significantly elevated, indicating the occurrence of apoptosis. The presence of MTB was able to abolish the JNK activation, cytochrome c release, and caspase-3 activation induced by Cu-OxVLDL or Cu-OxLDL, resulting in a marked reduction in apoptosis in endothelial cells. The data from this study indicate that oxidized lipoproteins induce apoptosis in endothelial cells. We postulate that the inhibition of the JNK signaling pathway by MTB is a key mechanism that protects these cells from oxidized lipoprotein-induced apoptosis.

Overexpression of Mitofusin 2 inhibited oxidized low-density lipoprotein induced vascular smooth muscle cell proliferation and reduced atherosclerotic lesion formation in rabbit

Our previous studies have implies that Mitofusin 2 (Mfn2), which was progressively reduced in arteries from ApoE(-/-) mice during the development of atherosclerosis, may take part in pathogenesis of atherosclerosis. In this study, we found that overexpression of Mfn2 inhibited oxidized low-density lipoprotein or serum induced vascular smooth muscle cell proliferation by down-regulation of Akt and ERK phosphorylation. Then we investigated the in vivo role of Mfn2 on the development of atherosclerosis in rabbits using adenovirus expressing Mitofusin 2 gene (AdMfn2). By morphometric analysis we found overexpression of Mfn2 inhibited atherosclerotic lesion formation and intima/media ratio by 66.7% and 74.6%, respectively, compared with control group. These results suggest that local Mfn2 treatment suppresses the development of atherosclerosis in vivo in part by attenuating the smooth muscle cell proliferation induced by lipid deposition and vascular injury.

Brain microvascular and intracranial artery resistance to atherosclerosis is associated with heme oxygenase and ferritin in Japanese quail

Oxidative stress and increased oxidation of low-density lipoprotein (oxLDL) through free radical-mediated tissue injury may be important factors in the development of extracranial atherosclerotic lesions. However, the roles of oxidative stress and hypercholesterolemia in intracranial atherosclerosis is less established. The induction of heme oxygenase (HO) is a cellular response to oxidative stress, and inducible HO (HO-1) may protect against oxidized lipids such as those produced by oxidative stress. We investigated the effects of oxLDL on cell and tissue viability, HO-1 and ferritin expression in extracranial and intracranial endothelial cells, and the arteries of cholesterol-induced atherosclerosis (CIA) Japanese quail. We report that cultured microvascular endothelial cells from the brain (QBMEC) and carotid (QCEC) differ in their response to oxidative stress. The QCECs are less responsive than QBMECs to oxidative stress induced by oxLDL, as evident by lower expression of HO-1 mRNA, HO activity, and ferritin levels. Furthermore, the higher levels of catalytic iron, thiobarbituric acid reactive substances, and lactate dehydrogenase released in QCECs indicated that these cells are more susceptible to oxidative stress than QBMECs. We also investigated the relationship between extent of atherosclerotic plaque deposition and the extracranial and intracranial arterial expression of HO-1 in quail. The common carotid and vertebral (extracranial) arteries had higher tissue cholesterol levels (starting at 2 weeks of cholesterol-supplementation) and a greater atherosclerotic plaque score (starting at 4 weeks of cholesterol-supplementation) compared with middle cerebral and basilar (intracranial) arteries, and this may be relevant to the effect of aging on the process of atherogenesis. The extracranial arteries also had early and greater levels of lipid peroxidation and catalytic iron coupled with lower expression of HO-1 protein, HO activity, and ferritin compared to the intracranial vessels. These observations suggest that the extracranial and intracranial arterial walls respond differently to oxidation of lipoproteins, and support the feasibility of increased HO-1 expression as a means of protection against oxidant injury.

Pigment epithelium-derived factor inhibits neointimal hyperplasia after vascular injury by blocking NADPH oxidase-mediated reactive oxygen species generation

Pigment epithelium-derived factor (PEDF) inhibits cytokine-induced endothelial cell activation through its antioxidative properties. However, the effect of PEDF on restenosis remains to be elucidated. Because the pathophysiological feature of restenosis is characterized by increased superoxide formation and accumulation of smooth muscle cells (SMCs), PEDF may inhibit this process via suppression of reactive oxygen species generation. We investigated here whether PEDF could prevent neointimal formation after balloon injury. PEDF levels were decreased in balloon-injured arteries. Adenoviral vector encoding human PEDF (Ad-PEDF) prevented neointimal formation. Expression and superoxide generation of the membrane components of NADPH oxidase, p22(phox) and gp91(phox), in the neointima were also suppressed by Ad-PEDF. Ad-PEDF reduced G(1) cyclin (cyclin D1 and E) expression and increased p27, a cyclin-dependent kinase inhibitor. In vitro, PEDF inhibited platelet-derived growth factor-BB-induced SMC proliferation and migration by blocking reactive oxygen species generation through suppression of NADPH oxidase activity via down-regulation of p22(PHOX) and gp91(PHOX). PEDF down-regulated G(1) cyclins and up-regulated p27 levels in platelet-derived growth factor-BB-exposed SMCs as well. These results demonstrate that PEDF could inhibit neointimal formation via suppression of NADPH oxidase-mediated reactive oxygen species generation. Our present study suggests that substitution of PEDF may be a novel therapeutic strategy for restenosis after balloon angioplasty.