KR‐31378 ameliorates atherosclerosis by blocking monocyte recruitment in hypercholestrolemic mice

Low-dose aspirin ameliorated hyperlipidemia, adhesion molecule, and chemokine production induced by high-fat diet in Sprague-Dawley rats

In this study the effects of low-dose aspirin (5 mg/kg) on adhesion molecule and chemokine expression in a hyperlipidemic rat model. Six-week-old Sprague-Dawley (SD) rats were assigned to two control groups receiving either a regular diet or high-fat diet (HFD) and a treatment group fed HFD with 5 mg/kg aspirin for a 10-week period. Compared with the regular diet control group, the HFD control group had higher body weight, lower levels of high-density lipoprotein, higher concentrations of insulin, triglyceride, total cholesterol, and low-density lipoprotein, but no differences in blood glucose and glycated hemoglobin. The prothrombin time (PT) and activated partial thromboplastin time (aPTT) were clearly shortened in the HFD group. That group also had increased expression of intercellular adhesion molecule-1 (ICAM-1), ICAM-2, ICAM-3, vascular cell adhesion molecule (VCAM), platelet endothelial cell adhesion molecule (PECAM) and P-selectin in platelets and vascular adhesion protein-1 in lymphocyte and in aorta increased expressions of ICAM-1, ICAM-2, ICAM-3, VCAM, PECAM, E-selectin, monocyte chemoattractant protein-1 (MCP-1) and CCR2. The HFD rats also had increased PKCα, IκB kinase α (IKKα), p65, mitogen-activated protein kinases (MAPKs) (p38, c-Jun N-terminal kinases 1, extracellular signal-regulated kinase 1/2), and their phosphorylated forms. Low-dose aspirin improved HFD-induced hyperinsulinemia and hyperlipidemia, recovered PT and aPTT, inhibited upregulation of adhesion molecules and chemokines and reduced expression of PKCα, IKKα, p65, and MAPKs. Low-dose aspirin ameliorates HFD-induced hyperlipidemia and hyperinsulinemia, and prevents HFD-induced expression of adhesion molecules and chemokine formation.

KR-31543 reduces the production of proinflammatory molecules in human endothelial cells and monocytes and attenuates atherosclerosis in mouse model

KR-31543, (2S, 3R, 4S)-6-amino-4-[N-(4-chlorophenyl)- N-(2-methyl-2H-tetrazol-5-ylmethyl) amino]-3,4-dihydro- 2-dimethyoxymethyl-3-hydroxy-2-methyl-2H-1-benz opyran is a new neuroprotective agent for ischemiareperfusion damage. It has also been reported that KR-31543 has protective effects on lipid peroxidation and H₂O₂-induced reactive oxygen species production. In this study, we investigated the anti-inflammatory and anti-atherogenic properties of KR-31543. We observed that KR-31543 treatment reduced the production of MCP-1, IL-8, and VCAM-1 in HUVECs, and of MCP-1 and IL-6 in THP-1 human monocytes. We also examined the effect of KR-31543 on monocytes migration in vitro. KR-31543 treatment effectively reduced the migration of THP-1 human monocytes to the HUVEC monolayer in a dose-dependent manner. We next examined the effects of this compound on atherogenesis in LDL receptor deficient (Ldlr ⁻/⁻) mice. After 10 weeks of western diet, the formation of atherosclerotic lesion in aorta was reduced in the KR-31543-treated group compared to the control group. The accumulation of macrophages in lesion was also reduced in KR-31543 treated group. However, the plasma levels of total cholesterol, HDL, LDL, and triglyceride were not affected by KR-31543 treatment. Taken together, these results show that KR-31543 has anti-inflammatory properties on human monocytes and endothelial cells, and inhibits fatty streak lesion formation in mouse model of atherosclerosis, suggesting the potential of KR-31543 for the treatment for atherosclerosis.

Aqueous extract of unripe Rubus coreanus fruit attenuates atherosclerosis by improving blood lipid profile and inhibiting NF-κB activation via phase II gene expression

ETHNOPHARMACOLOGICAL RELEVANCE

The fruit of Rubus coreanus has been used as a traditional herbal medicine for alleviation of inflammatory and vascular diseases in Asian countries.

AIM OF THE STUDY

The anti-atherogenic effect of unripe Rubus coreanus fruit extract (URFE) and its underlying mechanism were analyzed in mice fed a high-fat diet (HFD) and in cell culture system.

MATERIALS AND METHODS

Mouse was freely given HFD alone or supplemented with URFE for 14 weeks, followed by analysis of atherosclerotic lesions and serum lipid levels. For in vitro assay, macrophages were pretreated with URFE, followed by stimulation with lipopolysaccharide (LPS). Expression levels of inflammatory genes (TNF-α, IL-1β, and iNOS) and phase II genes (heme oxygenase-1, glutamate cysteine lygase, and peroxiredoxine-1) as well as intracellular reactive oxygen species (ROS) level and NF-κB activation pathway were analyzed in cultured macrophages as well as mouse sera and aortic tissues.

RESULTS

URFE supplementation reduced HFD-induced atherosclerotic lesion formation which was correlated with decreased levels of lipids, lipid peroxides, and inflammatory mediators (TNF-α, IL-1β, and nitric oxide) in sera as well as suppression of inflammatory gene in aortic tissues. In addition, pre-treatment of macrophages with URFE also suppressed LPS-induced NF-κB activation, ROS production, and inflammatory and phase II gene expressions. Inhibition of phase II enzyme and protein activities attenuated the suppressive effects URFE on ROS production, NF-κB activation, and inflammatory gene expression.

CONCLUSION

These results suggest that URFE attenuates atherosclerosis by improving blood lipid profile and inhibiting NF-κB activation via phase II antioxidant gene expression.

Eugenosedin-A prevents high-fat diet increased adhesion molecules through inhibition of MAPK- and p65-mediated NF-κB pathway in rat model

Objectives

Previous studies have shown eugenosedin-A, a 5-HT1B/2A and α1/α2/β1-adrenergic blocker, is able to decrease cholesterol levels, hyperglycaemia and inflammation in hyperlipidaemic mice induced by high-fat diet (HFD). The aim of this study is to examine the effects of eugenosedin-A on the inhibition of adhesion molecules of platelets, the aorta and acyl-coenzymeA:cholesterol acyltransferase-1 (ACAT-1) of macrophages in a hyperlipidaemic rat model.

Methods

Six-week-old Sprague–Dawley rats were randomly divided into two control and treatment groups. The control rats received either a regular diet or HFD and the treatment groups were fed HFD with either 5 mg/kg eugenosedin-A or atorvastatin for a 10-week period.

Key findings

Compared with the two control groups, the HFD group had lower levels of high-density lipoprotein, higher concentrations of triglycerides, total cholesterol, low-density lipoprotein and insulin. The expression of adhesion molecules in platelets, aorta and monocyte-macrophage were enhanced by HFD. HFD also increased upstream proteins and their phosphorylated form in the aorta. In treatment groups, eugenosedin-A and atorvastatin improved HFD-induced hyperlipidaemia and levels of insulin. Eugenosedin-A reduced the upregulation of P-selectin, ICAM-1, ICAM-2, ICAM-3, VCAM, PECAM in platelets and inhibited E-selectin, ICAM-1, ICAM-2, ICAM-3, VCAM and PECAM protein levels in the aorta. Eugenosedin-A reduced the ACAT-1 protein expression of monocyte-macrophages. The expression of PKCα, MAPKs, IKKα and p65 and their phosphorylated form were reduced in treatment groups.

Conclusions

Taken together, hyperlipidaemia enhances the expression of adhesion molecules and ACAT-1 protein, and eugenosedin-A ameliorates those increases. Through inhibition of MAPK- and p-65-mediated NF-κB pathway, eugenosedin-A decreases the quantity of adhesion molecules.

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.

Anti-atherogenic effect of BHB-TZD having inhibitory activities on cyclooxygenase and 5-lipoxygenase in hyperlipidemic mice

Cyclooxygenase (COX) and 5-lipoxygenase (5-LOX), which play pivotal roles in atherogenesis, have been reported to be involved in plaque stability. Licofelone, a dual COX and 5-LOX inhibitor, has been reported to possess anti-atherogenic effect in rabbit atherosclerosis model. We therefore investigated the anti-atherogenic effect of BHB-TZD [5-(3,5-di-tert-butyl-4-hydroxybenzylidene)thiazolidin-2,4-dione], a dual COX and 5-LOX inhibitor, in low density lipoprotein receptor null (LDLR-/-) mice. Fifteen LDLR-/- mice were fed a western diet (control group), whereas 15 were fed a western diet plus 0.1% (w/w) BHB-TZD (BHB-TZD group). After 8 weeks, the BHB-TZD group had markedly lower serum levels of leukotriene B(4) and prostaglandin E(2) than the control group. Interestingly, BHB-TZD treatment also reduced plasma triglyceride level without significant changes in total cholesterol and HDL levels. Compared with control mice, BHB-TZD fed mice had 52% fewer fatty streak lesions in the aortic sinus, as well as fewer initial lesions in the aortic arch. Macrophage infiltration into the lesions was 40% lower, and collagen and smooth muscle cells were increased by 102% and 96%, respectively, in the BHB-TZD group compared with the control group. In addition, aortic expression of proatherogenic molecules including TNF-alpha, IL-1beta, IL-6, MCP-1 and VCAM-1, was lower in the BHB-TZD group than the control group. BHB-TZD treatment also reduced MMP-2 and MMP-9 expressions in aorta. In conclusion, BHB-TZD effectively attenuated atherosclerosis in mouse model, suggesting its therapeutic potential for atherosclerosis.

Natural therapeutic magnesium lithospermate B potently protects the endothelium from hyperglycaemia-induced dysfunction

AIMS

We have investigated the effects of magnesium lithospermate B (MLB), the active compound of the Oriental herbal remedy, Salvia miltiorrhizae, on endothelial dysfunction associated with diabetes mellitus using cultured endothelial cells and an animal model of type 2 diabetes mellitus.

METHODS AND RESULTS

The effect of MLB on vasodilatory function in Otsuka Long-Evans Tokushima Fatty (OLETF) rats was assessed. MLB treatment for 20 weeks starting at 12 weeks attenuated the decrease in endothelium-dependent vasodilation in OLETF rats. MLB treatment also increased serum nitrite level and reduced serum advanced glycation end products concentration. The effect of MLB was greater than an equivalent dose of alpha-lipoic acid (alphaLA), a popular antioxidant treatment. MLB rescued the inhibition of endothelial nitric oxide synthase (eNOS) activity and eNOS phosphorylation in endothelial cells cultured in hyperglycaemia. This effect was dependent on Akt phosphorylation and associated with decreased O-linked N-acetylglucosamine protein modification of eNOS. MLB also increased nuclear factor erythroid 2-related factor-2 (Nrf-2) activation in a phosphoinositide 3-kinase/Akt pathway dependent manner. MLB treatment induced the expression of the Nrf-2-regulated antioxidant enzyme, heme oxygenase-1. The antioxidant alphaLA could not produce this effect. Moreover, MLB decreased oxidative stress and endothelial cell apoptosis caused by hyperglycaemia.

CONCLUSION

MLB is a naturally occurring, new generation antioxidant that activates eNOS and ameliorates endothelial dysfunction in diabetes by enhancing vasodilation in addition to reducing oxidative stress. The relative strong performance of MLB makes it an ideal candidate for further, expanded trials as a new generation of antioxidant to treat diabetes-related complications.

A selective NFkappaB inhibitor, DHMEQ, reduced atherosclerosis in ApoE-deficient mice

BACKGROUND AND PURPOSE

Atherosclerosis is a chronic inflammatory process, and anti-inflammatory agents potentially inhibit the development of atherosclerosis. We tested whether a novel NFkappaB inhibitor reduces atherosclerosis.

METHODS

Dehydroxymethylepoxyquinomicin (10 mg/kg) or vehicle (chloromethyl cellulose) was injected intraperitoneally into apoE-deficient mice three times a week for 16 weeks. The entire aorta was excised and atherosclerotic area was determined at 4 and 16 weeks. Serum levels of cholesterol, triglyceride, TNF-alpha and adiponectin were also measured.

RESULTS

The atherosclerotic area was significantly smaller in mice treated with dehydroxymethyl-epoxyquinomicin both at 4 and 16 weeks. There was no significant difference in body weight or serum levels of cholesterol, triglyceride, and adiponectin.

CONCLUSIONS

A new NFkappaB inhibitor, dehydroxymethylepoxyquinomicin, reduced atherosclerosis without affecting plasma lipid levels in apoE-deficient mice.

Glabridin suppresses intercellular adhesion molecule-1 expression in tumor necrosis factor-alpha-stimulated human umbilical vein endothelial cells by blocking sphingosine kinase pathway: implications of Akt, extracellular signal-regulated kinase, and nuclear factor-kappaB/Rel signaling pathways

(R)-4-(3,4-Dihydro-8,8-dimethyl)-2H,8H-benzo[1,2-b:3,4-b'] dipyran-3yl)-1,3-benzenediol (glabridin) is known to have anti-inflammatory, antimicrobial, and cardiovascular protective activities. In the present study, we report the inhibitory effect of glabridin on intercellular adhesion molecule-1 (ICAM-1) expression in tumor necrosis factor-alpha (TNF-alpha)-stimulated human umbilical vein endothelial cells (HUVECs). Glabridin inhibited THP-1 cell adhesion to HUVECs stimulated by TNF-alpha and cell surface expression of ICAM-1 in TNF-alpha-stimulated HUVECs. The mRNA expression of adhesion molecules, including ICAM-1, vascular cell adhesion molecule-1, and E-selectin, was also suppressed by glabridin. Further study demonstrated the inhibitory effect of glabridin on nuclear factor (NF)-kappaB/Rel DNA binding, inhibitory factor-kappaB alpha (IkappaB alpha), and IkappaB beta degradation, IkappaB kinase activation, and p65 nuclear translocation in TNF-alpha-stimulated HUVECs. Treatment of a variety of cell lines with glabridin revealed that inhibitory effect of glabridin on NF-kappaB/Rel activation is not cell type-specific, and both inducible and constitutive NF-kappaB/Rel activation was suppressed by glabridin treatment. Moreover, TNF-alpha-induced phosphorylation of Akt and extracellular signal-regulated kinase (ERK) was blocked by glabridin treatment in HUVECs. Glabridin also suppressed sphingosine-1-phosphate (S1P)-induced cell surface expression and mRNA expression of ICAM-1. Further study demonstrated that TNF-alpha-induced sphingosine kinase activity was inhibited by glabridin, and the inhibitory effect of glabridin on TNF-alpha-induced ICAM-1 expression was reversed by addition of exogenous S1P. Together, our results indicate that the inhibitory effect of glabridin on ICAM-1 expression might be mediated, at least in part, by inhibiting sphingosine kinase pathway and subsequent inhibition of signaling pathways, including Akt, ERK, and NF-kappaB/Rel signaling pathway.

Trichostatin A exacerbates atherosclerosis in low density lipoprotein receptor-deficient mice

OBJECTIVE

Histone acetylation has been shown to be involved in expression of a restricted set of cellular genes including various proinflammatory molecules. We aimed to investigate the relationship between histone acetylation and atherosclerosis.

METHODS AND RESULTS

In low-density lipoprotein (LDL) receptor-deficient (Ldlr(-/-)) mice fed an atherogenic diet for 4 or 8 weeks, trichostatin A (TSA), a specific histone deacetylase inhibitor, exacerbated atherosclerosis without alteration on plasma lipid profiles. When we assayed the effects of TSA on expressions of oxidized LDL (oxLDL) receptors on RAW264.7 macrophage, we found that TSA increased CD36 mRNA and protein, as well as cell surface expression of CD36. TSA also increased acetylation at the CD36 promoter region. The uptake of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine percholate (Dil)-labeled oxLDL was enhanced in RAW264.7 macrophage by TSA. Furthermore, TSA treatment increased CD36 mRNA expression in aorta, and SRA, tumor necrosis factor (TNF)-alpha, and vascular cell adhesion molecule-1 (VCAM-1) were also elevated, whereas IL-6 and IL-1beta expressions were decreased.

CONCLUSIONS

Our findings suggest that histone acetylation could play some role in atherogenesis by modulating expressions of oxLDL receptor and some proatherogenic genes. Therefore, our results indicate that increased histone acetylation may affect the progress of atherosclerosis.

Oxidative stress during the chronic phase after stroke

Stroke is a complex disease originating and developing on the background of genetic predisposition and interaction between different risk factors that chronically damage blood vessels. The search for an effective treatment of stroke patients is the main priority of basic and clinical sciences. The chronic phase of stroke provides possibilities for therapy directed toward stimulation of recovery processes as well as prophylaxis, which reduces the probability of subsequent cerebrovascular events. Oxidative stress is a potential contributor to the pathophysiological consequences of stroke. The aim of the present review is to summarize the current knowledge of the role of oxidative stress during the chronic phase after stroke and its contribution to the initiation of subsequent stroke. The relationship among inflammation, hemostatic abnormalities, and platelet activation in chronic stroke patients is discussed in the context of ongoing free radical processes and oxidative damage. Free radical-mediated effects of increased plasma level of homocysteine and its possible contribution to the processes leading to recurrent stroke are discussed as well. The status of the antioxidant defense system and the degree of oxidative damage in the circulation of stroke survivors are examined. The results are interpreted in view of the effects of the vascular risk factors for stroke that include additional activation of inflammatory and free radical mechanisms. Also, the possibilities for combined therapy including antioxidants in the acute and convalescent stages of stroke are considered. Future investigations are expected to elucidate the role of free radical processes in the chronic phase after stroke and to evaluate the prophylactic and therapeutic potential of anti-radical agents.

KR-31378 protects cardiac H9c2 cells from chemical hypoxia-induced cell death via inhibition of JNK/p38 MAPK activation

Using a metabolic inhibition buffer as an ischemic model, we show here that KR-31378, a cardioselective ATP-sensitive potassium channel opener, protects H9c2 cells from chemical hypoxia (CH)-induced cell death. Our previous study showed that CH downregulated caspase activities, but led to differential activation of mitogen-activated protein kinases (MAPKs) in H9c2 cells. The repression of CH-induced c-jun N-terminal kinase (JNK)/p38 MAPK activation resulted in partial protection against CH- induced cell death, implying JNK/p38 MAPK's causative role in CH-induced cell death. This study furthers that research and examines if KR-31378's protective effect came from modulating MAPK activity and/or caspase activity in H9c2 cells. Although KR-31378 did not restore downregulated caspase-3 activity, it did block the activation of JNK and p38 MAPK in a dose-dependent manner. Extracellular signal-regulated kinase activity was not recovered by KR-31378 treatment. CH-induced reactive oxygen species (ROS) generation was suppressed by KR-31378. Thus our results indicate that the cardioprotective effect of KR-31378 in CH is due, at least in part, to the differential inhibition of MAPKs.