Vitamin E inhibits low-density lipoprotein-induced adhesion of monocytes to human aortic endothelial cells in vitro

α-Tocopherol reduces VLDL secretion through modulation of intracellular ER-to-Golgi transport of VLDL

Avoiding hepatic steatosis is crucial for preventing liver dysfunction, and one mechanism by which this is accomplished is through synchronization of the rate of very low density lipoprotein (VLDL) synthesis with its secretion. Endoplasmic reticulum (ER)-to-Golgi transport of nascent VLDL is the rate-limiting step in its secretion and is mediated by the VLDL transport vesicle (VTV). Recent in vivo studies have indicated that α-tocopherol (α-T) supplementation can reverse steatosis in nonalcoholic fatty liver disease, but its effects on hepatic lipoprotein metabolism are poorly understood. Here, we investigated the impact of α-T on hepatic VLDL synthesis, secretion, and intracellular ER-to-Golgi VLDL trafficking using an in vitro model. Pulse-chase assays using [3H]-oleic acid and 100 µmol/L α-T demonstrated a disruption of early VLDL synthesis, resulting in enhanced apolipoprotein B-100 expression, decreased expression in markers for VTV budding, ER-to-Golgi VLDL transport, and reduced VLDL secretion. Additionally, an in vitro VTV budding assay indicated a significant decrease in VTV production and VTV-Golgi fusion. Confocal imaging of lipid droplet (LD) localization revealed a decrease in overall LD retention, diminished presence of ER-associated LDs, and an increase in Golgi-level LD retention. We conclude that α-T disrupts ER-to-Golgi VLDL transport by modulating the expression of specific proteins and thus reduces VLDL secretion.

Vitamin E: Where Are We Now in Vascular Diseases?

Vitamin E is one of the most popular fat-soluble vitamins in pathological research and has been under scrutiny since the 1980s as a vital dietary component of food. The antioxidant effect of vitamin E has been widely studied due to its benefits in the prevention of various cardiovascular diseases. In recent years, alternative effects of vitamin E, in terms of anti-inflammatory pathways and gene regulation, have also been of interest to researchers. This review examines the role of dietary vitamin E (α-tocopherol) as an antioxidant and bioactive molecule in promoting vascular health. While the antioxidant effect of vitamin E is well established, knowledge about its capacity as a promising regulatory molecule in the control of the vascular system is limited. The aim of this review is to discuss some of these mechanisms and summarize their role in the prevention of cardiovascular diseases (CVD). Here, we also briefly discuss foods rich in vitamin E, and deliberate some potential toxicological effects of excessive supplemental vitamin E in the body.

Serum Vitamins and Homocysteine Levels in Obsessive-Compulsive Disorder: A Systematic Review and Meta-Analysis

Vitamin and homocysteine (Hcy) alternations have been associated with psychiatric disorders. The aim of this meta-analysis was to assess the association of serum vitamin and Hcy levels with obsessive-compulsive disorder (OCD). Following PRISMA protocol, we used the databases including Scopus, PubMed, Google Scholar, and Web of Science with no time restriction. Data were pooled using a random-effects model and/or fixed-effects model to estimate the standard mean difference (SMD) for evaluation of the strength of association analyses. Our data showed a significant reduction in vitamin B12 (SMD = -0.58, 95% CI = -1.08 to -0.08, p = 0.02, I2 = 65%; pheterogeneity = 0.06), vitamin E (SMD = -0.89, 95% CI = -1.23 to -0.56, p < 0.00001, I2 = 23%; pheterogeneity = 0.26), and vitamin C (SMD = -1.40, 95% CI = -2.44 to -0.36, p = 0.008, I2 = 92%; pheterogeneity < 0.0001) in OCD patients. In addition, the findings showed significantly higher levels of Hcy (SMD = 1.11, 95% CI = [0.48, 1.75], p = 0.0006, I2 = 73%; ph = 0.02) in patients compared to controls. Also, our data showed that vitamin B9 and D levels are not associated with OCD (vitamin B9: SMD = -0.23, 95% CI = -1.01 to 0.55, p = 0.56, I2 = 88%; pheterogeneity < 0.0001; vitamin D: SMD = -0.63, 95% CI = -1.41 to 0.15, p = 0.11, I2 = 88%; pheterogeneity = 0.0002). Our findings support significant impacts of Hcy and vitamin B12, E, and C levels in OCD pathogenesis. This will be important for prevention and treatment of OCD. However, further studies are recommended to elucidate more accurate conclusions.

Interventional study with vitamin E in cardiovascular disease and meta-analysis

Cardiovascular disease (CVD) is one of the major causes of morbidity and mortality and atherosclerosis is the common root to most of the CVD. Oxidative stress is one of the most important factors driving atherosclerosis and its complications. Thus, strategies for the prevention and treatment of cardiovascular events had oxidative changes as a potential target. Natural vitamin E consists of a family of eight different compounds, four tocopherols and four tocotrienols. All tocopherols and tocotrienols are potent antioxidants with lipoperoxyl radical-scavenging activities. In addition, α-tocopherol possesses also anti-inflammatory as well as anti-atherothrombotic effects by modulating platelet and clotting system. Experimental and in vitro studies described molecular and cellular signalling pathways regulated by vitamin E antithrombotic and antioxidant properties. While observational studies demonstrated an inverse association between vitamin E serum levels and CVD, interventional trials with vitamin supplements provided negative results. This review focus on the impact of vitamin E in the atherothrombotic process and describes the results of experimental and clinical studies with the caveats related to the interventional trials with vitamin E to prevent CVD.

Effects of cannabinoids on the development of chick embryos in ovo

We have examined the effects of the synthetic cannabinoids HU 210 and HU 211, the plant-derived cannabidiol and the endogenous cannabinoid anandamide on the viability and development of chick embryos. Fertilized White Leghorn chicken eggs were injected with the test compounds or carrier vehicle, via a drilled small hole in the egg, directly into the egg yolk. After nine days of exposure, the embryonal viability, length and wet weight of embryos, and wet weight of brains were measured, and the development stages were assessed according to the Hamburger and Hamilton (HH) scale. The potent synthetic cannabinoid receptor agonist HU 210 and the non-psychotropic cannabidiol were embryotoxic at the highest concentrations examined (10 µM and 50 µM, respectively), with no viable embryos after the HU 210 injection, and 20% viability after the cannabidiol injections. The effects of HU 210 on the chick embryo were attenuated by α-tocopherol and the cannabinoid receptor antagonist AM251, whereas only α-tocopherol gave a statistically significant protection against the embryotoxic effects of cannabidiol. This study shows that exposure to plant-derived or synthetic cannabinoids during early embryonal development decreases embryonal viability. Extrapolation of data across species is of course difficult, but the data would argue against the use of cannabinoids, be it recreationally or therapeutically, during pregnancy.

α-Tocopherol and Atherosclerosis

Cardiovascular disease is the leading cause of morbidity and mortality in the Western world. There is compelling evidence incriminating oxidative stress in the pathogenesis of the atherosclerotic lesion. Several lines of evidence suggest that antioxidants, especially α-tocopherol, have potential beneficial effects with regard to cardiovascular disease. In vitro, α-tocopherol has been shown to inhibit platelet adhesion and aggregation and smooth muscle cell proliferation, exert anti-inflammatory effects on monocytes, and improve endothelial function. Also, supplementation with α-tocopherol has been shown to decrease lipid peroxidation, platelet aggregation, and pro-inflammatory activity of monocytes. However, clinical trials with α-tocopherol supplementation to date have been equivocal. Thus, although mounting in vitro evidence and animal models provide a sound scientific basis for α-tocopherol supplementation, further clinical trials are required before a definitive recommendation can be made with respect to the primary and secondary prevention of heart disease.

C-Reactive Protein Increases Oxygen Radical Generation by Neutrophils

C-reactive protein (CRP) has been suggested to play a role in the pathogenesis of atherosclerosis. Neutrophil respiratory burst and levels of CRP are increased during infection. The increase in the neutrophil respiratory burst may be due to factors that are elevated in infection, such as cytokines, tumor necrosis factor, platelet-activating factor, and CRP. The direct effect of CRP on the release of oxygen radicals by neutrophils is not known. This investigation was made to determine if CRP affects the generation of oxygen radicals by neutrophils and if this effect is blocked by antioxidants. The effect of various concentrations (1 to 200 µg/mL blood) of CRP on the generation of oxygen radicals by neutrophils was measured as luminol-dependent chemiluminescence (chemiluminescent activity) on a luminometer (Auto Lumat LB953, EG & G Berthold, Gaithersburg, MD). The unit of chemiluminescent activity is the relative light unit and was expressed as relative light unit/white blood cell (RLU/WBC). Chemiluminescent activity of blood without CRP was slightly higher than that of buffer with or without CRP. CRP markedly increased the chemiluminescent activity of blood. There was no significant change in the chemiluminescent activity of WBCs with 1 µg/mL of CRP. The chemiluminescent activity increased significantly with higher concentrations of CRP. The percent increases in the chemiluminescent activity with 2, 5, 10, 25, 50, 100 and 200 µg/mL of CRP were 45%, 72%, 50%, 70%, 52%, 67%, and 68% respectively. Antioxidants (superoxide dismutase, catalase, and dimethylthiourea) blocked CRP-induced oxygen radicals by WBCs. These results suggest that CRP increases the generation of oxygen radicals from the WBCs. CRP-induced atherosclerosis may be mediated through generation of oxygen radicals by neutrophils.

A Study on Regression of Hypercholesterolemic Atherosclerosis in Rabbits by Flax Lignan Complex

Flax lignan complex (FLC) isolated from flaxseed suppresses the development of hypercholesterolemic atherosclerosis. The objectives of this study were to investigate if FLC produces regression of atherosclerosis and if regression is associated with reductions in serum lipids and oxidative stress. The studies were conducted in 4 groups of rabbits: group I, control diet (2 months); group II, 0.25% cholesterol diet (2 months); group III, 0.25% cholesterol diet (2 months) followed by regular diet (4 months); and group IV, 0.25% cholesterol diet (2 months) followed by regular diet and FLC (4 months). Serum lipids and oxidative stress parameters were measured before and at various intervals thereafter on their respective diets. The aortas were removed at the end of the protocol for assessment of atherosclerotic plaques and oxidative parameters. Atherosclerosis in group II was associated with hyperlipidemia and increased oxidative stress. Atherosclerotic changes were accelerated in group III, and this was associated with reductions in serum lipids and oxidative stress. Atherosclerotic lesions in group IV were similar to group II, but significantly smaller than those in group III, and were associated with reductions in serum lipids and oxidative stress similar to that in group III. These results indicate that FLC does not produce regression but prevents the acceleration of atherosclerosis due to the removal of cholesterol in the diet. These effects of FLC are not associated with reductions in serum lipids and oxidative stress.

Pathophysiology and Medical Treatment of Carotid Artery Stenosis

Stroke is the third leading cause of mortality. Approximately 80 to 85% strokes are ischemic due to carotid artery stenosis (CAS). The prevalence of significant CAS is 7% in women and 9% in men. Severe asymptomatic CAS varies from 0 to 3.1%. Prevalence of symptomatic CAS is high in patients with peripheral arterial disease. CAS is due to atherosclerosis, the major risk factors for which include dyslipidemia, hypertension, diabetes, obesity, cigarette smoking, advanced glycation end products (AGEs) and its receptors (RAGE, soluble RAGE [sRAGE]), lack of exercise and C-reactive protein (CRP). This article discusses the basic mechanism of atherosclerosis and the mechanisms by which these risk factors induce atherosclerosis. The role of AGEs and its receptors in the development and progression of CAS has been discussed in detail. Lifestyle changes and medical treatment of CAS such as lifestyle changes, lipid-lowering agents, antihypertensive agents, antidiabetic drugs, anti-AGE therapy, measures to elevate soluble receptors of AGE (sRAGE, esRAGE). CRP-lowering agents have been discussed in detail. The drugs especially lipid-lowering agents, and antihypertensive and antidiabetic drugs suppress, regress, and slow the progression of CAS. The possible role of lowering the levels of AGEs and raising the levels of sRAGE in the treatment of CAS has been proposed. Lifestyle changes besides medical treatment have been stressed. Lifestyle changes and medical treatment not only would slow the progression of CAS but would also regress the CAS.

Role of Advanced Glycation End Products and Its Receptors in the Pathogenesis of Cigarette Smoke-Induced Cardiovascular Disease

The interaction of advanced glycation end products (AGEs) with its cell-bound receptor RAGE increases gene expression and release of proinflammatory cytokines and increase generation of reactive oxygen species (ROS). Circulating receptors, soluble RAGE (sRAGE), and endosecretory RAGE (esRAGE) by binding with RAGE ligands have protective effects against AGE-RAGE interaction. Cigarette smoking is a risk factor for coronary artery disease, stroke, and peripheral vascular disease. This article reviews; if the AGE-RAGE axis is involved in the cigarette smoke-induced cardiovascular diseases. There are various sources of AGEs in smokers including, gas/tar of cigarette, activation of macrophages and polymorphonuclear leukocytes, uncoupling of endothelial isoform of nitric oxide synthase (eNOS) and xanthine oxidase. The levels of AGEs are elevated in smokers. Serum levels of sRAGE have been reported to be reduced, elevated, or unchanged in smokers. Mostly the levels are reduced. There is one article which shows an elevation of levels of sRAGE in smokers. Serum levels of esRAGE are unaltered in smokers. Mechanism of AGE-RAGE-induced atherosclerosis has been discussed. Atherosclerosis leads to the cardiovascular diseases. It has been suggested that ratio of AGE/sRAGE or AGE/esRAGE is useful in determining the deleterious effects of AGE-RAGE interaction in smokers. sRAGE alone is not a good marker for smoke-induced cardiovascular disease. In conclusion cigarette smoke induces formation of AGEs and reduces sRAGE resulting in the development of atherosclerosis and related coronary heart disease, stroke, and peripheral vascular disease. Ratio of AGEs/sRAGE is a better marker for cardiovascular disease than AGEs or sRAGE alone in smokers.

Oxidative stress as a mechanism of added sugar-induced cardiovascular disease

Added sugars comprising of table sugar, brown sugar, corn syrup, maple syrup, honey, molasses, and other sweeteners in the prepared processed foods and beverages have been implicated in the pathophysiology of cardiovascular diseases. This article deals with the reactive oxygen species (ROS) as a mechanism of sugar-induced cardiovascular diseases. There is an association between the consumption of high levels of serum glucose with cardiovascular diseases. Various sources of sugar-induced generation of ROS, including mitochondria, nicotinamide adenine dinucleotide phosphate-oxidase, advanced glycation end products, insulin, and uric acid have been discussed. The mechanism by which ROS induce the development of atherosclerosis, hypertension, peripheral vascular disease, coronary artery disease, cardiomyopathy, heart failure, and cardiac arrhythmias have been discussed in detail. In conclusion, the data suggest that added sugars induce atherosclerosis, hypertension, peripheral vascular disease, coronary artery disease, cardiomyopathy, heart failure, and cardiac arrhythmias and that these effects of added sugars are mediated through ROS.

Vitamin E-gene interactions in aging and inflammatory age-related diseases: implications for treatment. A systematic review

Aging is a complex biological phenomenon in which the deficiency of the nutritional state combined with the presence of chronic inflammation and oxidative stress contribute to the development of many age-related diseases. Under this profile, the free radicals produced by the oxidative stress lead to a damage of DNA, lipids and proteins with subsequent altered cellular homeostasis and integrity. In young-adult age, the cell has a complex efficient system to maintain a proper balance between the levels of free radicals and antioxidants ensuring the integrity of cellular components. In contrast, in old age this balance is poorly efficient compromising cellular homeostasis. Supplementation with Vitamin E can restore the balance and protect against the deteriorating effects of oxidative stress, progression of degenerative diseases, and aging. Experiments in cell cultures and in animals have clearly shown that Vitamin E has a pivotal role as antioxidant agent against the lipid peroxidation on cell membranes preserving the tissue cells from the oxidative damage. Such a role has been well documented in immune, endothelial, and brain cells from old animals describing how the Vitamin E works both at cytoplasmatic and nuclear levels with an influence on many genes related to the inflammatory/immune response. All these findings have supported a lot of clinical trials in old humans and in inflammatory age-related diseases with however contradictory and inconsistent results and even indicating a dangerous role of Vitamin E able to affect mortality. Various factors can contribute to all the discrepancies. Among them, the doses and the various isoforms of Vitamin E family (α,β,γ,δ tocopherols and the corresponding tocotrienols) used in different trials. However, the more plausible gap is the poor consideration of the Vitamin E-gene interactions that may open new roadmaps for a correct and personalized Vitamin E supplementation in aging and age-related diseases with satisfactory results in order to reach healthy aging and longevity. In this review, this peculiar nutrigenomic and/or nutrigenetic aspect is reported and discussed at the light of specific polymorphisms affecting the Vitamin E bioactivity.

Vitamin E isoforms differentially regulate intercellular adhesion molecule-1 activation of PKCα in human microvascular endothelial cells

Aims

ICAM-1-dependent leukocyte recruitment in vivo is inhibited by the vitamin E isoform d-α-tocopherol and elevated by d-γ-tocopherol. ICAM-1 is reported to activate endothelial cell signals including protein kinase C (PKC), but the PKC isoform and the mechanism for ICAM-1 activation of PKC are not known. It is also not known whether ICAM-1 signaling in endothelial cells is regulated by tocopherol isoforms. We hypothesized that d-α-tocopherol and d-γ-tocopherol differentially regulate ICAM-1 activation of endothelial cell PKC.

Results

ICAM-1 crosslinking activated the PKC isoform PKCα but not PKCβ in TNFα-pretreated human microvascular endothelial cells. ICAM-1 activation of PKCα was blocked by the PLC inhibitor U73122, ERK1/2 inhibitor PD98059, and xanthine oxidase inhibitor allopurinol. ERK1/2 activation was blocked by inhibition of XO and PLC but not by inhibition of PKCα, indicating that ERK1/2 is downstream of XO and upstream of PKCα during ICAM-1 signaling. During ICAM-1 activation of PKCα, the XO-generated ROS did not oxidize PKCα. Interestingly, d-α-tocopherol inhibited ICAM-1 activation of PKCα but not the upstream signal ERK1/2. The d-α-tocopherol inhibition of PKCα was ablated by the addition of d-γ-tocopherol.

Conclusions

Crosslinking ICAM-1 stimulated XO/ROS which activated ERK1/2 that then activated PKCα. ICAM-1 activation of PKCα was inhibited by d-α-tocopherol and this inhibition was ablated by the addition of d-γ-tocopherol. These tocopherols regulated ICAM-1 activation of PKCα without altering the upstream signal ERK1/2. Thus, we identified a mechanism for ICAM-1 activation of PKC and determined that d-α-tocopherol and d-γ-tocopherol have opposing regulatory functions for ICAM-1-activated PKCα in endothelial cells.

Anti-Inflammatory effect of Buddleja officinalis on vascular inflammation in human umbilical vein endothelial cells

Vascular inflammation process has been suggested to be an important risk factor in the initiation and development of atherosclerosis. In this study, we investigated whether and by what mechanisms an aqueous extract of Buddleja officinalis (ABO) inhibited the expressions of cellular adhesion molecules, which are relevant to inflammation and atherosclerosis. Pretreatment of human umbilical vein endothelial cells (HUVEC) with ABO (1-10 microg/ml) for 18 hours dose-dependently inhibited TNF-alpha-induced adhesion U937 monocytic cells, as well as mRNA and protein expressions of vascular cell adhesion molecule-1 (VCAM-1), and intercellular cell adhesion molecule-1 (ICAM-1). Pretreatment with ABO also blocked TNF-alpha-induced ROS formation. Nuclear factor-kappa B (NF-kappaB) is required in the transcription of these adhesion molecule genes. Western blot analysis revealed that ABO inhibits the translocation of the p65 subunit of NF-kappaB to the nucleus. ABO inhibited the TNF-alpha-induced degradation of IkappaB-alpha, an inhibitor of NF-kappaB, by inhibiting the phosphorylation of IkappaB-alpha in HUVEC. Taken together, ABO could reduce cytokine-induced endothelial adhesiveness throughout down-regulating intracellular ROS production, NF-kappaB, and adhesion molecule expression in HUVEC, suggesting that the natural herb Buddleja officinalis may have potential implications in atherosclerosis.

Effect of caffeic acid on tumor necrosis factor-alpha-induced vascular inflammation in human umbilical vein endothelial cells

Recruitment of specific leukocyte subpopulations at the site of inflammation requires a series of cell adhesion molecules (CAMs)-mediated interactions. The major CAMs, viz., intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin are expressed on endothelium in response to various cytokines. Caffeic acid (CA), a natural phenolic compound from herbs and other sources, has been shown to prevent cardiovascular diseases. We investigated the effect of CA on the expression of CAMs by human umbilical vein endothelial cells (HUVECs) stimulated with tumor necrosis factor (TNF-alpha). Adhesion of monocytes to CA-treated HUVECs was evaluated by co-culture experiments using 2,7-bis(2-carboxyethyl)-5(6)-carboxyfluorescein acetoxymethylester (BCECF-AM) labeling of U937 cells. The expression of adhesion and chemoattractant molecules was evaluated by Western blot and reverse transcription-polymerase chain reaction (RT-PCR), respectively. CA significantly inhibited the TNF-alpha-induced increase in U937 monocyte adhesion to HUVECs as well as decreased the protein and mRNA expression levels of CAMs on HUVECs. CA also inhibited the mRNA expression of monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8). The involvement of nuclear factor (NF)-kappaB in the transcriptional control of CAMs protein was assessed by degradation of inhibitory (I)kappaB and nuclear translocation of NF-kappaB using Western blotting and immunofluorescence staining. CA attenuated TNF-alpha-induced IkappaB degradation and NF-kappaB translocation from cytosol to the nucleus. In conclusion, TNF-alpha-induced NF-kappaB-DNA complex formation was inhibited by CA. CA reduced TNF-alpha-induced endothelial adhesiveness to HUVECs by inhibiting transcription factor activation, and CAMs expression suggesting its potential role in atherosclerosis diseases.

Vitamin E Does Not Regress Hypercholesterolemic Atherosclerosis

Background: Suppression of hypercholesterolemic atherosclerosis with vitamin E is associated with reductions in oxidative stress without reductions in serum lipids. The objectives of this study were to determine if (1) vitamin E regresses hypercholesterolemic atherosclerosis; and (2) regression is associated with reductions in serum lipids and aortic oxidative stress. Methods and Results: The studies were conducted in 4 groups of rabbits: group I, control, regular diet (2 months); group II, 0.25% cholesterol diet (2 months); group III, 0.25% cholesterol diet (2 months) followed by regular diet (2 months); and group IV, 0.25% cholesterol diet (2 months) followed by regular diet with vitamin E (40 mg/kg body weight/day) (2 months). Blood samples were collected monthly for the measurement of serum lipids and oxidative stress (chemiluminescent activity of white blood cells [WBC-CL]). Aortas were removed at the end of the protocol for assessment of atherosclerotic lesions, and oxidative stress (malondialdehyde [MDA] and CL). Increases in serum lipids in group II were associated with an increase in oxidative stress and development of atherosclerosis. Serum lipids decreased to a similar extent in groups III and IV but the atherosclerotic lesions increased by 63% and 141% compared to group II. Acceleration of atherosclerosis in the rabbits on regular diet with or without vitamin E was associated with practically no change in the oxidative stress. Conclusion: These results suggest that (1) regular diet following a high-cholesterol diet decreased oxidative stress but did not induce regression of atherosclerosis; (2) vitamin E did not produce regression; and (3) regular diet with vitamin E following a high-cholesterol diet was not associated with an increase in oxidative stress but produced acceleration of atherosclerosis.

Flax Lignan Complex Slows Down the Progression of Atherosclerosis in Hyperlipidemic Rabbits

Flax lignan complex suppresses the development of hypercholesterolemic atherosclerosis. However, it is not known whether flax lignan complex would slow down the progression of hypercholesterolemic atherosclerosis. This study was carried out to determine whether flax lignan complex slows down the progression of already developed atherosclerosis, and whether this effect is associated with reductions in serum lipids and oxidative stress. The studies were conducted in 4 groups of rabbits: group I, regular diet (2 months); group II, 0.25% cholesterol diet (2 months); group III, 0.25% cholesterol diet (4 months); group IV, 0.25% cholesterol diet (2 months) followed by 0.25% cholesterol diet plus flax lignan complex (2 months). Serum lipids and oxidative stress parameters (malondialdehyde, antioxidant reserve, white blood cell chemiluminescence) were measured before and at monthly intervals thereafter on their respective diets. Aortas were removed at the end of the protocol for assessment of atherosclerosis and oxidative stress. Atherosclerosis in group II was associated with hyperlipidemia and increased oxidative stress. Significant areas of the aortic intimal surfaces from group II (37.76% + 7.96%), group III (76.6% + 9.04%), and group IV (52.95% + 10.29%) were covered with atherosclerotic plaques. Group IV rabbits had 40% more atherosclerotic lesions than group II but 31% fewer lesions than group III. The flax lignan complex—induced reduction in the progression of atherosclerosis was associated with reductions in oxidative stress. In conclusion, flax lignan complex was effective in slowing down the progression of atherosclerosis by 31%, and this effect was associated with a reduction in oxidative stress.

Oxidative stress in prehypertension: rationale for antioxidant clinical trials

Prehypertension has been recently described as an independent category of blood pressure. Mounting evidence suggests that blood pressure in the prehypertensive range is associated with an increased risk of developing hypertension and cardiovascular disease. Several reports have assigned a critical role for oxidative stress in these disease processes. This review focuses on the clinical and experimental studies done in prehypertension and hypertension within the context of oxidative stress. This article also provides insights into why diverse therapeutic interventions, which have in common the ability to reduce oxidative stress, can impede or delay the onset of hypertension in prehypertension subjects.

Diallyl disulfide and diallyl trisulfide suppress oxidized LDL-induced vascular cell adhesion molecule and E-selectin expression through protein kinase A- and B-dependent signaling pathways

Uptake of oxidized LDL (ox-LDL) by vascular endothelial cells is a critical step in the initiation and development of atherosclerosis. Adhesion molecules are upregulated by ox-LDL and numerous inflammatory cytokines and play a pivotal role in atherogenesis. In this study, we examined whether diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS), 3 major organosulfur compounds of garlic oil, reduce adhesion molecule expression induced by ox-LDL and, if so, through what mechanism. Human umbilical vein endothelial cells were preincubated with 1 mmol/L DAS, 200 mumol/L DADS, or 100 mumol/L DATS for 16 h and then with 40 mg/L ox-LDL for an additional 24 h. ox-LDL induction of cellular and cell surface expression of E-selectin and vascular cell adhesion molecule (VCAM)-1 was suppressed by garlic allyl sulfides in the order DATS > DADS > DAS. The adhesion of HL-60 cells to endothelial cells was inhibited 27 and 33% and the production of cellular peroxides was inhibited 43 and 50% by DADS and DATS, respectively (P < 0.05). ox-LDL alone dephosphorylated protein kinase B (PKB) and cAMP responsive element binding protein (CREB); such deactivation was reversed by DADS and DATS. Electrophoretic mobility shift assay showed that the activation of CREB binding to DNA was consistent with changes in CREB phosphorylation. The protein kinase A (PKA) inhibitor H89 reversed the suppression of VCAM-1 by DADS and DATS, but the phosphoinositide 3-kinase (PI3K) inhibitor wortmannin had no effect. In contrast, wortmannin abolished DADS- and DATS-induced suppression of ox-LDL-induced E-selectin expression. These results suggest that the suppression of ox-LDL-induced E-selectin and VCAM-1 expression by DADS and DATS and, thus, monocyte adhesion to endothelial cells is likely dependent on the PI3K/PKB or PKA/CREB signaling pathway in an adhesion molecule-specific manner. To our knowledge, this is the first report that garlic modulates ox-LDL-mediated leukocyte adhesion to human endothelial cells through the PKB and PKA pathways.

Attenuation of the development of hypercholesterolemic atherosclerosis by thymoquinone

Thymoquinone (TQ), derived from Nigella sativa seed, is an antioxidant. The present study investigated whether TQ attenuates the development of atherosclerosis, and/or reduces the serum lipid levels and oxidative stress in rabbits. New Zealand white female rabbits were assigned to four groups of six animals each: group I, control; group II, 1% cholesterol diet; group III, 1% cholesterol plus TQ (10 mg/kg/day; through a nasogastric tube) diet; and group IV, 1% cholesterol plus TQ (20 mg/kg/day; through a nasogastric tube) diet. Blood samples were collected at baseline and after four and eight weeks on the experimental diets for measurement of serum lipids, total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), TC/HDL-C ratio and oxidative stress biomarkers (malondialdehyde [MDA] and protein carbonyls). At the end of the eight weeks, the aorta was removed for the assessment of atherosclerotic changes, MDA and protein carbonyls. Group II animals developed atherosclerosis (45%±11% of the intimal surface of aorta was covered with atherosclerotic plaques), which was associated with an increase in the serum TC, TG, LDL-C, HDL-C, TC/HDL-C, MDA and protein carbonyls. In group III, TQ decreased serum TC, LDL-C, MDA and protein carbonyls by 26%, 29%, 85% and 62%, respectively, and aortic MDA by 73%, which was associated with a 40% reduction of the development of aortic atherosclerosis. The higher dose of TQ in group IV had effects similar to the lower dose (group III), except that this dose further decreased serum TG. It is concluded that TQ attenuates hypercholesterolemic atherosclerosis and this effect is associated with a decrease in serum lipids and oxidative stress.

Regression of hypercholesterolemic atherosclerosis in rabbits by secoisolariciresinol diglucoside isolated from flaxseed

Secoisolariciresinol diglucoside (SDG) isolated from flaxseed is a lipid-lowering and antioxidant agent. It suppresses the development of hypercholesterolemic atherosclerosis in rabbits. It is however not known if SDG would produce regression of atherosclerosis. The objectives of this study were to determine (i) if SDG produces regression of atherosclerosis; (ii) if regression is associated with reduction in serum lipids, oxidative stress or both; and (iii) if the duration of treatment has an effect on regression. Rabbits were assigned to five groups: Group I, regular diet (control); Group II, 0.5% cholesterol diet for 2 months (mo); Group III, same as Group II but followed by regular diet for 2 mo; Group IV, same as Group II and followed by regular diet with SDG (20mg x kg body wt(-1) x day(-1) PO) for 2 mo; and Group V, same as Group IV but SDG treatment for an additional 2 mo. Blood samples were collected from rabbits before and at monthly intervals thereafter on their respective diet regimen for measurement of triglycerides (TG), total cholesterol (TC), LDL-C, HDL-C and malondialdehyde (MDA), a lipid peroxidation product. At the end of the protocol, the aorta was removed for assessment of atherosclerotic lesions, aortic MDA and aortic chemiluminescence (Aortic-CL), a measure of antioxidant reserve. MDA and Aortic-CL provide an index of oxidative stress. Increases in serum TG, TC, LDL-C, HDL-C and the risk ratio TC/HDL-C in Group II were associated with an increase in oxidative stress and development of atherosclerosis (57% of aortic intimal surface covered with lesions). Serum lipids decreased to a similar extent in Groups III-V, however atherosclerotic lesions were 84%, 63% and 44%, respectively in Groups III-V. There were more atherosclerotic lesions in Group III (+48.9%) as compared to Group II. The atherosclerotic lesions decreased by 24% and 45%, respectively in Groups IV and V compared to Group III. The reduction in atherosclerotic lesions was associated with a reduction in oxidative stress. These results suggest that (i) regular diet following a high cholesterol diet accelerates atherosclerosis in spite of a decrease in serum lipids; (ii) SDG treatment prevents the progression of atherosclerosis on a regular diet following a high cholesterol diet; (iii) prevention of progression is associated with a reduction of aortic oxidative stress and not with reductions in serum lipids; (iv) a longer duration of treatment reduces the progression of atherosclerosis to a greater extent, and tends to regress the atherosclerosis.

Antioxidant activity and metabolite profile of quercetin in vitamin-E-depleted rats

Dietary antioxidants interact in a dynamic fashion, including recycling and sparing one another, to decrease oxidative stress. Limited information is available regarding the interrelationships in vivo between quercetin and vitamin E. We investigated the antioxidant activity and metabolism of quercetin (Q) in 65 F-344 rats (n=13 per group) randomly assigned to the following vitamin E (VE)-replete and -deficient diets: (a) VE replete (30 mg alpha-tocopherol acetate/kg diet) control ad libitum (C-AL), (b) VE replete pair fed (C-PF), (c) VE replete+5.0 g Q/kg diet (R-VE+5Q), (d) VE deplete (<1 mg/kg total tocopherols)+5.0 g Q/kg diet (D-VE+5Q) and (e) D-VE. After 12 weeks, blood and tissue were collected for measurement of plasma vitamin E, quercetin and its metabolites, serum pyruvate kinase (PK), plasma protein carbonyls, malondialdehyde (MDA) and oxygen radical absorbance capacity. D-VE diets decreased serum alpha-tocopherol and increased PK activity in a time-dependent manner. The D-VE diet increased plasma protein carbonyls but did not affect MDA. Dietary quercetin supplementation increased quercetin and its metabolites in plasma and liver but did not affect D-VE-induced changes in plasma alpha-tocopherol, PK or protein carbonyls. Plasma isorhamnetin and its disposition in muscle were enhanced by the D-VE diet, as compared to the R-VE diet. Conversely, tamarixetin disposition in muscle was decreased by the D-VE diet. Thus, quercetin did not slow vitamin E decline in vivo; neither did it provide antioxidant activity in vitamin-E-depleted rats. However, vitamin E status appears to enhance the distribution of isorhamnetin into the circulation and its disposition in muscle.

Cellular, molecular and clinical aspects of vitamin E on atherosclerosis prevention

Randomised clinical trials and epidemiologic studies addressing the preventive effects of vitamin E supplementation against cardiovascular disease reported both positive and negative effects, and recent meta-analyses of the clinical studies were rather disappointing. In contrast to that, many animal studies clearly show a preventive action of vitamin E in several experimental settings, which can be explained by the molecular and cellular effects of vitamin E observed in cell cultures. This review is focusing on the molecular effects of vitamin E on the cells playing a role during atherosclerosis, in particular on the endothelial cells, vascular smooth muscle cells, monocytes/macrophages, T cells, and mast cells. Vitamin E may act by normalizing aberrant signal transduction and gene expression in antioxidant and non-antioxidant manners; in particular, over-expression of scavenger receptors and consequent foam cell formation can be prevented by vitamin E. In addition to that, the cellular effects of alpha-tocopheryl phosphate and of EPC-K1, a composite molecule between alpha-tocopheryl phosphate and l-ascorbic acid, are summarized.

Ellagic acid inhibits IL-1β-induced cell adhesion molecule expression in human umbilical vein endothelial cells

Expression of cell adhesion molecules by endothelium and the attachment of monocytes to endothelium may play a major role in atherosclerosis. Ellagic acid (EA) is a phenolic compound found in fruits and nuts including raspberries, strawberries, grapes and walnuts. Previous studies have indicated that EA possesses antioxidant activityin vitro. In the present study, we investigated the effects of EA on the formation of intracellular reactive oxygen species, the translocation of NFκB and expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 and endothelial leucocyte adhesion molecule (E-selectin) induced by IL-1β in human umbilical vein endothelial cells (HUVEC). We found that EA significantly reduced the binding of human monocytic cell line, U937, to IL-1β-treated HUVEC. The production of reactive oxygen species by IL-1β was dose-dependently suppressed by EA. Supplementation with increasing doses of EA up to 50 μmol/l was most effective in inhibiting the expression of VCAM-1 and E-selectin. Furthermore, the inhibition of IL-1β-induced adhesion molecule expression by EA was manifested by the suppression of nuclear translocation of p65 and p50. In conclusion, EA inhibits IL-1β-induced nuclear translocation of p65 and p50, thereby suppressing the expression of VCAM-1 and E-selectin, resulting in decreased monocyte adhesion. Thus, EA has anti-inflammatory properties and may play an important role in the prevention of atherosclerosis.

Oxidative stress, antioxidants, and vascular damage

Oxidative stress has been recognized as a key mechanism in the development of vascular damage, particularly atherosclerosis. In spite of substantial experimental evidence demonstrating reversal of endothelial dysfunction and prevention of atherosclerosis in experimental settings, no benefits have been observed in large clinical trials in which antioxidants have been given in high-risk patients for the prevention of cardiovascular events. Evaluation of the clinical relevance of the oxidative modification hypothesis requires identification of potential molecular targets of antioxidant interventions and effective antioxidant agents. Future research should necessarily consider quantification of interindividual variations in oxidative stress using appropriate biomarkers.

Heart disease and single-vitamin supplementation

Heart disease is the number one cause of death in the United States and has long been recognized to be multifactorial. A growing body of evidence suggests that not only free radical-mediated reactions but also inflammatory responses play major roles in atherogenesis. Vitamin E has both antioxidant and antiinflammatory properties and is the most widely studied vitamin in clinical trials and thus will be the primary example used in this review. Clinical trials of vitamin E efficacy, in hindsight, have been overly optimistic in their expectation that a vitamin could reverse poor dietary habits and a sedentary lifestyle as well as provide benefit beyond that of pharmaceutical agents in treating heart disease. However, it is also apparent that most Americans do not consume dietary amounts adequate to meet established vitamin E requirements. In response to oxidative stressors, vitamin E can decrease biomarkers of lipid peroxidation, is itself killed, and requires optimal vitamin C status to function most effectively. Thus, adequate vitamin E intakes are clearly needed, but what is adequate for what function has yet to be defined. It is noteworthy that in most trials, biomarkers were not used nor were oxidative stress and lipid peroxidation markers used or plasma vitamin E concentrations measured.

Suppression of hypercholesterolemic atherosclerosis by pentoxifylline and its mechanism

Reactive oxygen species (ROS) have been implicated in the development of hypercholesterolemic atherosclerosis. Hypercholesterolemia increases the levels of platelet activating factor (PAF) and cytokines which are known to stimulate granulocytes and endothelial cells to produce ROS. Pentoxifylline (PTX) is an inhibitor of cytokines and PAF and would reduce the generation of ROS by granulocytes and endothelial cells. PTX therefore would be expected to reduce the development of hypercholesterolemic atherosclerosis. New Zealand white female rabbits were assigned to four groups: Group I (n=12), control; Group II (n=5), PTX control (40 mg/kg body weight daily orally); Group III (n=13), 0.5% cholesterol; Group IV (n=9), 0.5% cholesterol+PTX (40 mg/kg body weight daily orally). Blood samples were collected before (0 time) and after 1 and 2 months on experimental diets for measurement of serum triglycerides (TG), total cholesterol (TC), LDL-C, HDL-C and serum malondialdehyde (MDA), a lipid peroxidation product. At the end of 2 months the aorta was removed for measurement of atherosclerotic plaques, MDA, and aortic tissue chemiluminescence (Ao-CL), a marker for antioxidant reserve. Rabbits in Group III developed atherosclerosis (56.61+/-6.90% of the intimal surface of aorta was covered with atherosclerotic plaques) which was associated with an increase in the serum TG, TC, LDL-C, HDL-C, TC/HDL-C, MDA and aortic MDA and antioxidant reserve. PTX reduced the development of atherosclerosis by 38.1% and this was associated with decreases in serum MDA by 32%, aortic MDA by 37%, and antioxidant reserve by 17.3% without changes in the serum lipids. These results suggest that ROS generated during hypercholesterolemia via cytokines and PAF may in part contribute to the development of hypercholesterolemic atherosclerosis and that suppression of production and activity of cytokines and PAF may reduce the development of hypercholesterolemic atherosclerosis.

Extrahepatic tissue concentrations of vitamin K are lower in rats fed a high vitamin E diet

BACKGROUND

An adverse hematological interaction between vitamins E and K has been reported, primarily in patients on anticoagulants. However, little is known regarding circulating levels or tissue concentrations of vitamin K in response to vitamin E supplementation. The purpose of this study was to examine the effect of different levels of dietary alpha-tocopherol on phylloquinone and menaquinone-4 concentrations, while maintaining a constant intake of phylloquinone, in rat tissues.

METHODS

Male 4-wk old Fischer 344 rats (n = 33) were fed one of 3 diets for 12 wk: control (n = 13) with 30 mg all-rac-alpha-tocopherol acetate/kg diet; vitamin E-supplemented (n = 10) with 100 mg all-rac-alpha-tocopherol acetate/kg diet; and vitamin E-restricted (n = 10) with <10 mg total tocopherols/kg diet. All 3 diets contained 470 +/- 80 microg phylloquinone/kg diet.

RESULTS

Phylloquinone concentrations were lower (P < or = 0.05) in the vitamin E-supplemented compared to the vitamin E-restricted group (mean +/- SD spleen: 531 +/- 58 vs. 735 +/- 77; kidney: 20 +/- 17 vs. 94 +/- 31, brain: 53 +/- 19 vs. 136 +/- 97 pmol/g protein respectively); no statistically significant differences between groups were found in plasma, liver or testis. Similar results were noted with menaquinone-4 concentrations in response to vitamin E supplementation.

CONCLUSION

There appears to be a tissue-specific interaction between vitamins E and K when vitamin E is supplemented in rat diets. Future research is required to elucidate the mechanism for this nutrient-nutrient interaction.

Chemical structure of flavonols in relation to modulation of angiogenesis and immune-endothelial cell adhesion

The antioxidant activity of flavonoids has been suggested to contribute to several health benefits associated with the consumption of fruits and vegetables. Four flavonols - myricetin (M), quercetin (Q), kaempferol (K) and galangin (G), all with different numbers of hydroxyl moieties (-OH) - were examined for their antioxidant activity and cytotoxicity on human umbilical vein endothelial cells (HUVECs) and for their potential antiangiogenic and cell adhesion effects. The relative antioxidant capacity of these flavonols in cell culture medium (cell-free system) and their intracellular antioxidant activity were M = Q > K = G, which correlated respectively with the presence of 3, 2, 1 and 0 moieties of -OH on their B-ring. The higher the numbers of -OH moieties on the B-ring the less toxic the flavonol was to HUVEC, and the LD50 was determined as: M (100 microM) > Q (50 microM) > K (20 microM) > G (10 microM). These flavonols at approximately 0.5 LD50 doses suppressed the vascular endothelial growth factor (VEGF)-stimulated HUVEC tubular structure formation by: M (47%) > Q (37%) > K (15%) > G (14%), which was not linearly associated with their numbers of -OH moieties. However, the magnitude of flavonols' suppression of activated U937 monocytic cells adhesion to HUVEC was associated with the number of -OH moieties on the B-ring. This was prominent when U937 cells were pretreated with these flavonols. In contrast, the numbers of -OH moiety had no apparent influence on the adhesion or expression of adhesion molecules when activated HUVECs were pretreated with these flavonols. The presence of different numbers of -OH moieties on the B-ring of the flavonols may contribute to their antioxidant activity as well as their toxicity and may play an important role in their potency for biological action such as angiogenesis and immune-endothelial cell adhesion, which, respectively, are important processes in the development of cancer and atherosclerosis.

Nutritional factors, cognitive decline, and dementia

Nutritional factors and nutritional deficiencies have been repeatedly associated with cognitive impairment. Most of the evidence is based on cross-sectional studies, which cannot prove whether a nutritional deficit is the cause or the consequence of an impaired cognitive status. In fact, cognitive impairment, in turn, can determine changes in dietary habits and consequent nutritional deficiencies. We reviewed clinical and epidemiological studies from January 1983 to June 2004. Several cross-sectional and fewer prospective studies reported an association between dietary or supplemental intake of antioxidants and protection from cognitive decline and dementia. There are negative reports as well and some methodological biases might have affected the consistencies across studies. Deficiencies of several B vitamins have been associated with cognitive dysfunction in many observational studies. More recently, deficiencies of folate (B9) and cobalamine (B12) have been studied in relation to hyperhomocysteinemia as potential determinants of cognitive impairment, dementia, and Alzheimer's disease (AD). A small number of studies assessed the association between intake of macronutrients and cognitive function or dementia. Among the others, the intake of fatty acids and cholesterol has received particular attention. Although the results are not always consistent, most studies have reported a protective role of dietary intakes of poly- and mono-unsaturated fatty acids against cognitive decline and AD. We point out that well designed intervention studies are warranted in order to establish specific levels of micro- and macronutrient deficiencies and to set general recommendations for the population.

Inhibition of tumor necrosis factor-α-induced expression of adhesion molecules in human endothelial cells by the saponins derived from roots of Platycodon grandiflorum

Adhesion molecules play an important role in the development of atherogenesis and are produced by endothelial cells after being stimulated with various inflammatory cytokines. This study examined the effect of saponins that were isolated from the roots of Platycodon grandiflorum A. DC (Campanulaceae), Changkil saponins (CKS), on the cytokine-induced monocyte/human endothelial cell interaction, which is a crucial early event in atherogenesis. CKS significantly inhibited the TNFalpha-induced increase in monocyte adhesion to endothelial cells as well as decreased the protein and mRNA expression levels of vascular adhesion molecule-1 and intercellular cell adhesion molecule-1 on endothelial cells. Furthermore, CKS significantly inhibited the TNFalpha-induced production of intracellular reactive oxygen species (ROS) and activation of NF-kappaB by preventing IkappaB degradation and inhibiting IkappaB kinase activity. Overall, CKS has anti-atherosclerotic and anti-inflammatory activity, which is least in part the result of it reducing the cytokine-induced endothelial adhesion to monocytes by inhibiting intracellular ROS production, NF-kappaB activation, and cell adhesion molecule expression in endothelial cells.

Antioxidants and endothelium protection

The endothelium is a complex organ system that controls the homeostasis of the vasculature by integrating signals between the vascular wall and the vessel lumen. Under physiological conditions, it maintains a normal vascular tone and blood fluidity by elaborating a variety of factors, such as nitric oxide, prostacyclin and endothelin. However, in pathological situations the endothelium can also modify its phenotype facilitating vasoconstriction, inflammation, and thrombotic events. These abnormal responses manifest in different clinical settings, such as hypercholesterolemia, hypertension, diabetes mellitus, and occur in the absence of any morphological change of the vessel. The etiology of these altered endothelial functions is multi-factorial, and the mechanisms underlying them are complex and not yet fully elucidated. Today, there is substantial evidence that many endothelial functions are sensitive to the presence of reactive oxygen species and subsequent oxidative stress. Here, I will review the increasing number of studies showing that exogenous antioxidants can modulate the endothelium-dependent vasodilation responses, the homeostatic endothelium-leukocyte interactions, the balance between pro- and anti-thrombotic properties, and the vascular apoptotic responses. Finally, the non-antioxidant activities of some antioxidant will also be described.

Vitamin E, oxidative stress, and inflammation

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the Western world. Its incidence has also been increasing lately in developing countries. Several lines of evidence support a role for oxidative stress and inflammation in atherogenesis. Oxidation of lipoproteins is a hallmark in atherosclerosis. Oxidized low-density lipoprotein induces inflammation as it induces adhesion and influx of monocytes and influences cytokine release by monocytes. A number of proinflammatory cytokines such as interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha) modulate monocyte adhesion to endothelium. C-reactive protein (CRP), a prototypic marker of inflammation, is a risk marker for CVD and it could contribute to atherosclerosis. Hence, dietary micronutrients having anti-inflammatory and antioxidant properties may have a potential beneficial effect with regard to cardiovascular disease. Vitamin E is a potent antioxidant with anti-inflammatory properties. Several lines of evidence suggest that among different forms of vitamin E, alpha-tocopherol (AT) has potential beneficial effects with regard to cardiovascular disease. AT supplementation in human subjects and animal models has been shown to decrease lipid peroxidation, superoxide (O2-) production by impairing the assembly of nicotinamide adenine dinucleotide phosphate (reduced form) oxidase as well as by decreasing the expression of scavenger receptors (SR-A and CD36), particularly important in the formation of foam cells. AT therapy, especially at high doses, has been shown to decrease the release of proinflammatory cytokines, the chemokine IL-8 and plasminogen activator inhibitor-1 (PAI-1) levels as well as decrease adhesion of monocytes to endothelium. In addition, AT has been shown to decrease CRP levels, in patients with CVD and in those with risk factors for CVD. The mechanisms that account for nonantioxidant effects of AT include the inhibition of protein kinase C, 5-lipoxygenase, tyrosine-kinase as well as cyclooxygenase-2. Based on its antioxidant and anti-inflammatory activities, AT (at the appropriate dose and form) could have beneficial effects on cardiovascular disease in a high-risk population.

Protocatechuic aldehyde suppresses TNF-alpha-induced ICAM-1 and VCAM-1 expression in human umbilical vein endothelial cells

Adhesion molecules, which play a crucial role in the development of atherogenesis, are produced by endothelial cells following stimulation with various inflammatory cytokines. The current studies examined the effect of a potent water-soluble antioxidant, protocatechuic aldehyde (derived from the Chinese herb, Salvia miltiorrhiza), on the expression of adhesion molecules in human umbilical vein endothelial cells (HUVECs) stimulated with tumor necrosis factor-alpha (TNF-alpha). Protocatechuic aldehyde appeared to specifically downregulate the TNF-alpha-induced cell surface expression of vascular adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) on HUVECs as well as the release of soluble VCAM-1and ICAM-1 from HUVECs in a dose-response manner at pharmacologically relevant concentrations (0.15-1.35 mM). We also observed a dose-dependent lowering of mRNA expression of VCAM-1 and ICAM-1 in the presence of protocatechuic aldehyde. Furthermore, protocatechuic aldehyde (0.15, 0.45, and 1.35 mM) notably inhibited TNF-alpha-induced upregulation of U937 cell adhesion to HUVECs to 83.7%, 60.9%, and 40.8%, respectively. A gel shift assay further showed that protocatechuic aldehyde inhibited the TNF-alpha-activated NF-kappaB and AP-1 DNA binding activities in a dose-dependent manner. Collectively, these results indicate that protocatechuic aldehyde inhibits TNF-alpha-stimulated VCAM-1 and ICAM-1expression in HUVECs through a mechanism that involves NF-kappaB and AP-1.

Vitamin E mediates cell signaling and regulation of gene expression

alpha-Tocopherol modulates two major signal transduction pathways centered on protein kinase C and phosphatidylinositol 3-kinase. Changes in the activity of these key kinases are associated with changes in cell proliferation, platelet aggregation, and NADPH-oxidase activation. Several genes are also regulated by tocopherols partly because of the effects of tocopherol on these two kinases, but also independently of them. These genes can be divided in five groups: Group 1. Genes that are involved in the uptake and degradation of tocopherols: alpha-tocopherol transfer protein, cytochrome P450 (CYP3A), gamma-glutamyl-cysteine synthetase heavy subunit, and glutathione-S-transferase. Group 2. Genes that are implicated with lipid uptake and atherosclerosis: CD36, SR-BI, and SR-AI/II. Group 3. Genes that are involved in the modulation of extracellular proteins: tropomyosin, collagen-alpha-1, MMP-1, MMP-19, and connective tissue growth factor. Group 4. Genes that are connected to adhesion and inflammation: E-selectin, ICAM-1 integrins, glycoprotein IIb, IL-2, IL-4, IL-1b, and transforming growth factor-beta (TGF-beta). Group 5. Genes implicated in cell signaling and cell cycle regulation: PPAR-gamma, cyclin D1, cyclin E, Bcl2-L1, p27, CD95 (APO-1/Fas ligand), and 5a-steroid reductase type 1. The transcription of p27, Bcl2, alpha-tocopherol transfer protein, cytochrome P450 (CYP3A), gamma-glutamyl-cysteine sythetase heavy subunit, tropomyosin, IL-2, and CTGF appears to be upregulated by one or more tocopherols. All the other listed genes are downregulated. Gene regulation by tocopherols has been associated with protein kinase C because of its deactivation by alpha-tocopherol and its contribution in the regulation of a number of transcription factors (NF-kappaB, AP1). A direct participation of the pregnane X receptor (PXR) / retinoid X receptor (RXR) has been also shown. The antioxidant-responsive element (ARE) and the TGF-beta-responsive element (TGF-beta-RE) appear in some cases to be implicated as well.

Vitamin E: Textbooks require updating

Vitamin E was discovered in 1922, but in more than 60 years many new findings have added to the early one. However, its description in many textbooks has not been proportionally updated. The result is an inaccurate, incomplete, and often incorrect description of the function of this vitamin. In some other textbooks, vitamin E is absolutely neglected. In almost all books the existence of vitamin E deficiency diseases is ignored. Recent findings on vitamin E molecular functions and its related diseases are described in this article.

Chemistry and biology of vitamin E

Our understanding of the role of vitamin E in human nutrition, health, and disease has broadened and changed over the past two decades. Viewed initially as nature's most potent lipid-soluble antioxidant (and discovered for its crucial role in mammalian reproduction) we have now come to realize that vitamin E action has many more facets, depending on the physiological context. Although mainly acting as an antioxidant, vitamin E can also be a pro-oxidant; it can even have nonantioxidant functions: as a signaling molecule, as a regulator of gene expression, and, possibly, in the prevention of cancer and atherosclerosis. Since the term vitamin E encompasses a group of eight structurally related tocopherols and tocotrienols, individual isomers have different propensities with respect to these novel, nontraditional roles. The particular beneficial effects of the individual isomers have to be considered when dissecting the physiological impact of dietary vitamin E or supplements (mainly containing only the alpha-tocopherol isomer) in clinical trials. These considerations are also relevant for the design of transgenic crop plants with the goal of enhancing vitamin E content because an engineered biosynthetic pathway may be biased toward formation of one isomer. In contrast to the tremendous recent advances in knowledge of vitamin E chemistry and biology, there is little hard evidence from clinical and epidemiologic studies on the beneficial effects of supplementation with vitamin E beyond the essential requirement.

Vitamin E supplementation suppresses macrophage accumulation and endothelial cell expression of adhesion molecules in the aorta of hypercholesterolemic rabbits

Suppression of cell adhesion molecule expression and macrophage accumulation by the endothelium is believed to play an important role in preventing the development of atherosclerosis. Earlier, we have shown that in vitro supplementation of human aortic endothelial cells with Vitamin E dose-dependently reduced expression of adhesion molecules and monocyte adhesion. Here, we report the in vivo down-regulation of endothelial cell adhesion molecules expression and macrophage accumulation in the aortas of hypercholesterolemic rabbits supplemented with Vitamin E. To this end, New Zealand White rabbits were fed a semi-purified diet containing 30 (control) or 1000 IU/kg Vitamin E. After 4 weeks, both groups' diets were switched to an atherogenic diet (0.3% cholesterol, 9% hydrogenated coconut oil, and 1% corn oil) containing the respective levels of Vitamin E and fed for 2, 4, and 6 weeks. Vitamin E supplemented rabbits had significantly higher levels of Vitamin E in their plasma and aortas. Frozen aorta sections were fixed and stained by an avidin-biotin complex method using Rb2/3 and Rb1/9 monoclonal antibodies against rabbit ICAM-1 and VCAM-1, respectively, and with RAM-11 for macrophage and von Willebrand factor for endothelial cells, followed by staining with secondary antibodies and counterstaining and evaluation under the microscope. At 6 weeks on atherogenic diet treatment, a trend (P = 0.08) toward a lower score of ICAM-1 expression by endothelial cells was observed in the aorta of Vitamin E treated rabbits compared to the control. However, a decrease in the score of VCAM-1 expression by endothelial cells in Vitamin E treated rabbits did not reach to a statistical significance. At 4 and 6 weeks on atherogenic diet, Vitamin E supplementation also significantly (P = 0.003) inhibited the accumulation of macrophages in the aorta. These results support the concept that down-regulation of adhesion molecule expression and suppression of monocyte/macrophage activation by Vitamin E in vivo is one of the potential mechanisms by which Vitamin E may suppress the development of aortic lesions in a rabbit model of atherosclerosis.

Vitamin E Modulation of Cardiovascular Disease

Endothelium in the vascular system is an important modulator of vasomotor tone and coagulation, and it plays a crucial role in the inhibition of adhesion and activation of platelets and leukocytes. Evidence indicates that dietary antioxidants may modulate these endothelium-dependent vascular functions through several mechanisms and may contribute to the prevention of vascular diseases such as atherosclerosis. Several cell cultures as well as animal and human clinical and observational studies have tested the efficacy of vitamin E on vascular function and the prevention of atherosclerosis. Our cell culture studies have indicated that vitamin E (alpha-tocopherol) inhibits the activation of endothelial cells stimulated by high levels of low-density lipoprotein cholesterol and pro-inflammatory cytokines. This inhibition is associated with the suppression of chemokines, the expression of cell surface adhesion molecules, and the adhesion of leukocytes to endothelial cells, all of which contribute to the development of lesions in the arterial wall. The molecular mechanisms by which alpha-tocopherol and other tocopherols modulate endothelial cells and smooth muscle functions have been delineated. We, and others, have also demonstrated a positive effect of dietary vitamin E on endothelium and vascular function in animal models of atherosclerosis. Several human clinical trials have also shown an improvement in the surrogate markers of atherosclerosis and vascular function by vitamin E supplementation. However, these findings have been contradicted by several vitamin E supplementation trials for the prevention of secondary cardiovascular events showing null effect. Intervention at a relatively late stage of disease and the single use of vitamin E rather than in combination with other antioxidants might have contributed to these contradictory findings. Evidence from cell cultures, as well as animal and human clinical and observational studies, strongly supports the contribution of dietary vitamin E to the maintenance of vascular function and health, in particular when it is used in combination with other dietary antioxidants, which are found in fruits, vegetables, and nuts.

Flavones mitigate tumor necrosis factor-alpha-induced adhesion molecule upregulation in cultured human endothelial cells: role of nuclear factor-kappa B

Flavones have been classified as anti-atherogenic agents that inhibit monocyte adhesion to stimulated endothelium, possibly by blocking induction of cell adhesion molecules (CAM). This anti-atherogenic feature of these flavonoids appears to be related to their chemical structures. Flavones may interfere with key signaling events involved in endothelial cell activation by inflammatory mediators. This study examined the effects of flavones on the induction of CAM and the translocation and DNA binding of nuclear factor-kappa B (NF-kappa B) in TNF-alpha-activated human umbilical vein endothelial cells (HUVEC). The effects of flavones, luteolin and apigenin, on adhesion of THP-1 monocytes to the TNF-alpha-activated HUVEC, protein expression and mRNA levels of vascular cell adhesion molecule-1 (VCAM-1), intracellular cell adhesion molecule-1 (ICAM-1) and E-selectin, and nuclear appearance and DNA binding activity of NF-kappa B were determined. Flavanols, flavonols, and flavanones were used for comparison. TNF-alpha significantly induced HUVEC protein expression of VCAM-1, ICAM-1, and E-selectin with increasing mRNA levels. Luteolin and apigenin inhibited the TNF-alpha-induced upregulation of THP-1 adhesion and VCAM-1 expression; these inhibitory effects were dose-dependent. The flavones at doses of > or =25 micromol/L almost completely abolished the increased CAM protein and mRNA regardless of their anti-oxidative activity. With the exception of the flavonol quercetin, flavonoids had no such effect; quercetin substantially attenuated the CAM induction. The flavones inhibited nuclear translocation and DNA binding activity of the NF-kappa B-containing binding site in the promoter region of the CAM genes in TNF-alpha-activated HUVEC. The inhibition of endothelial CAM induction by flavones is mediated by their interference with the NF-kappa B-dependent transcription pathway. Thus, the flavones may hamper initial atherosclerotic events involving endothelial CAM induction.

Dietary fat type affects vitamins C and E and biomarkers of oxidative status in peripheral and brain tissues of golden Syrian hamsters

Oxidative stress is an important trigger in the complex chain of events leading to neurodegenerative diseases. On the other hand, dietary fatty acids play an essential role in brain function. The objectives of this study were to assess the effect of dietary fat type on vitamin C and vitamin E (alpha-and gamma-tocopherol) concentrations in peripheral and brain tissues and its effect on 8-epiPGF(2)alpha (F(2)-isoprostanes). Male Golden Syrian hamsters (n = 120, 8 wk old) were fed diets enriched in butter, hydrogenated fat (margarine), and canola and soybean oils. After 12 wk, hamsters were deprived of food, anesthetized with isoflurane, and killed via terminal exsanguination. Analyses of vitamins C, E, and 8-epiPGF(2)alpha were performed in peripheral tissues and brain. Hamsters consuming the margarine-enriched diet had lower (P < 0.05) vitamin C and alpha-tocopherol concentrations in liver, plasma, and brain, and higher (P < 0.02) plasma 8-epiPGF(2)alpha than groups fed the butter, and the canola and soybean oil diets. Liver and plasma gamma-tocopherol concentration was higher (P < 0.001) among the groups fed the soybean- and margarine-enriched diets compared with the other groups. alpha-Tocopherol was higher (P < 0.05) and 8-epiPGF(2)alpha lower (P < 0.01) among the groups fed the canola and soybean oil diets compared with the other groups. Across the groups, an inverse correlation between plasma levels of vitamin C and 8-epiPGF(2)alpha (r = -0.37, P = 0.03) and a positive correlation between plasma levels of vitamin C and alpha-tocopherol were observed (r = 0.341, P = 0.003). Hamsters fed the butter-enriched diet had a higher (P < 0.03) plasma uric acid concentration than the other groups. The results of this study provide new evidence concerning the effect of dietary fat on antioxidant status, which is important for the maintenance of good health.

Cellular adhesion molecules and cardiovascular disease. Part II. Their association with conventional and emerging risk factors, acute coronary events and cardiovascular risk prediction

The role of cellular adhesion molecules in the patho-genesis of atherosclerosis has now been clearly demonstrated. Plasma levels of adhesion molecules, which have been shed from the cell surface, have also been associated with the presence of clinical atherosclerotic disease, cardiovascular risk factors and acute coronary syndromes. However, there is little consensus in the literature, including between the large well-designed population studies. This may be explained either by unrecognized confounding factors or, alternatively, by the unpredictable relationship between cell surface expression and activity of cellular adhesion molecules and their shedding into the plasma under different circumstances. Probably for the latter reasons, there is at present little evidence that the measurement of circulating adhesion molecules is likely to offer any additional benefit for individual patients above the assessment of conventional cardiovascular risk factors in the assessment of either the extent of, or future risk from, cardiovascular disease.

Regulation of gene expression by α-tocopherol

Several genes are regulated by tocopherols which can be categorized, based on their function, into five groups: genes that are involved in the uptake and degradation of tocopherols (Group 1) include α-tocopherol transfer protein (α-TTP) and cytochrome P450 (CYP3A); genes that are associated with lipid uptake and atherosclerosis (Group 2) include CD36, SRBI and SRAI/II. Genes that modulate the expression of extracellular proteins (Group 3) include tropomyosin, collagenα1, MMP-1, MMP-19 and connective tissue growth factor (CTGF). Genes that are related to inflammation, cell adhesion and platelet aggregation (Group 4) include Eselectin, ICAM-1, integrins, glycoprotein IIb, Il-2, IL-4 and IL-β. Group 5 comprises genes coding for proteins involved in cell signaling and cell cycle regulation and consists of PPARγ, cyclin D1, cyclin E, Bcl2-L1, p27 and CD95 (Apo-1/Fas ligand). The expression of P27, Bcl2, α-TTP, CYP3A, tropomyosin, Il-2, PPAR-γ, and CTGF appears to be up-regulated by one or more tocopherols whereas all other listed genes are down-regulated. Several mechanisms may underlie tocopherol-dependent gene regulation. In some cases protein kinase C has been implicated due to its deactivation by α-tocopherol and its participation in the regulation of a number of transcription factors (NFκB, AP-1). In other cases a direct involvement of PXR/ RXR has been documented. The antioxidant responsive element (ARE) appears in some cases to be involved as well as the transforming growth factor β responsive element (TGF-β-RE). This heterogeneity of mediators of tocopherol action suggests the need of a common element that could be a receptor or a co-receptor, able to interact with tocopherol and with transcription factors directed toward specific regions of promoter sequences of sensitive genes. Here we review recent results of the search for molecular mechanisms underpinning the central signaling mechanism.