The role of oxidative stress and NADPH oxidase in the pathogenesis of atherosclerosis.

Reactive oxygen species (ROS) play a key role in the pathogenesis of atherosclerosis. The main mechanisms which are involved are low-density lipoprotein oxidative modification, inactivation of nitric oxide and modulation of redox-sensitive signaling pathways. ROS contribute to several aspects of atherosclerosis including endothelial cell dysfunction, monocyte/macrophage recruitment and activation, stimulation of inflammation, and inducing smooth muscle cell migration and proliferation. NADPH oxidase is the main source of ROS in the vasculature. This enzyme consists of a membrane-bound heterodimer of gp91phox and p22phox, cytosolic regulatory subunits p47phox, p67phox and p40phox, and small GTP-binding proteins rac1 and rac 2. Seven distinct isoforms of this enzyme have been identified, of which four (NOX1, 2, 4 and 5) may have cardiovascular function. In this paper, we review the current state of knowledge concerning the role of oxidative stress and NOX enzymes in pathogenesis of atherosclerosis. Moreover, we analyze the experimental studies that explore the relationship between the NOX family and atherosclerosis.

Mycophenolic acid attenuates the tumour necrosis factor-α-mediated proinflammatory response in endothelial cells by blocking the MAPK/NF-κB and ROS pathways.

BACKGROUND: Mycophenolate mofetil (MMF) has beneficial effects in cardiac transplant patients beyond the suppression of tissue rejection. Moreover, mycophenolic acid (MPA), its active metabolite, has been associated with positive effects on atherosclerosis in animal models. The attachment of leukocytes to the vascular endothelium and the subsequent migration of these cells into the vessel wall are early events in inflammation and atherosclerosis. The aim of this study was to investigate the effects of MPA on tumour necrosis-α (TNF-α)-induced, endothelial cell proinflammatory responses and the underlying mechanisms. METHODS AND RESULTS: Human aortic endothelial cells (HAECs) were treated with different concentrations (primarily 50 µM) of MPA before treatment with TNF-α. The surface protein and mRNA expressions of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were determined by flow cytometry and real-time RT-PCR, respectively. Adhesion of leukocytes to TNF-α-treated HAECs was evaluated by an adhesion assay. Activation of mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) was evaluated by measuring the levels of their phosphorylation using flow cytometry. NF-κB p65 translocation was detected by Western blotting. The production of reactive oxygen species (ROS) was determined by reduction in fluorescent 2',7'-dichlorofluorescein diacetate (H2 DCFH-DA). MPA significantly inhibits TNF-α-induced ICAM-1, VCAM-1 surface protein and mRNA expression as well as adhesion of mononuclear leukocytes to HAEC. ICAM-1 and VCAM-1 expressions were also reduced by antioxidants such as pyrrolidine dithiocarbamate, diphenylene iodonium and apocynin. MPA inhibited TNF-α-stimulated ROS generation similarly to apocynin. TNF-α increased ICAM-1 and VCAM-1 expression via c-Jun NH2 -terminal kinase (JNK), extracellular signal-regulated kinase (ERK1/2) and p38 MAPK. MPA and apocynin inhibited TNF-α-induced phosphorylation of all three MAP kinases. Furthermore, TNF-α-induced NF-κB activation was attenuated by SP600125 (JNK inhibitor), PD98059 (ERK1/2 inhibitor, SB203580 (p38 MAPK inhibitor) and MPA. MPA also inhibited TNF-α-induced nuclear translocation of NF-κB p65. CONCLUSION: These results suggest that, in addition to the prevention of rejection, MPA may be a promising approach for the treatment of inflammatory vascular disease.

[Mitogen-activated protein kinases in atherosclerosis]. / Kinazy aktywowane mitogenami i ich znaczenie w patogenezie miazdzycy.

Intracellular signalling cascades, in which MAPK (mitogen-activated protein kinases) intermediate, are responsible for a biological response of a cell to an external stimulus. MAP kinases, which include ERK1/2 (extracellular signalling-regulated kinase), JNK (c-Jun N-terminal kinase) and p 38 MAPK, regulate the activity of many proteins, enzymes and transcription factors and thus have a wide spectrum of biological effects. Many basic scientific studies have defined numerous details of their pathway organization and activation. There are also more and more studies suggesting that individual MAP kinases probably play an important role in the pathogenesis of atherosclerosis. They may mediate inflammatory processes, endothelial cell activation, monocyte/macrophage recruitment and activation, smooth muscle cell proliferation and T-lymphocyte differentiation, all of which represent crucial mechanisms involved in pathogenesis of atherosclerosis. The specific inhibition of an activity of the respective MAP kinases may prove a new therapeutic approach to attenuate atherosclerotic plaque formation in the future. In this paper, we review the current state of knowledge concerning MAP kinase-dependent cellular and molecular mechanisms underlying atherosclerosis.

Mycophenolate mofetil--a new atheropreventive drug?

Atherosclerosis is a form of chronic inflammation in which endothelial cell dysfunction, fibroproliferative process, oxidative stress and inflammatory cell activation are linked to plaque development and destabilization. T-lymphocytes also play a key role in pathogenesis of atherosclerosis. As a consequence, the suggested concept that modulation of an immunological response could be an appropriate target in the prevention of cardiovascular disease, is an important focus of research. Mycophenolate mofetil (MMF) is an inhibitor of inosine monophosphate dehydrogenase (IMPDH), that exerts anti-proliferative and pro-apototic effects, particularly on activated T-lymphocytes. MMF has other anti-atherogenic effects at the level of endothelial cells, monocytes/macrophages, smooth muscle cells and dendritic cells. In addition, MMF exhibits anti-oxidative properties. The present review paper provides an overview about the mechanisms of anti-atherosclerotic properties of MMF.

Bovine corneal epithelial primary cultures as an in vitro model for ophthalmic drugs studies.

In the recent years a significant development of investigations with regard to bioavailability of ocular drugs has been noticed. The corneal epithelial barrier is the main pathway for ocular penetration of topically applied ophthalmic drugs into the anterior chamber. To work out an in vitro model of bovine corneal epithelial primary cultures and exercise it for permeability research with lipophilic and hydrophilic markers, permeability coefficients estimation of the 6-carboxyfluorescein and rhodamin B was made. The corneal epithelial cultures of the 3th or 4th passage were chosen for layered culture with inserts based on the liquid-liquid interface (for the first week) and the air-liquid interface (for the two following weeks). On the 7th, 12th, 18th, 21st experiment day TER values, and on the 21st day drug permeability coefficients, were determined. The mean TER values of the 7th, 12th, 18th, 21st day of corneal epithelial culture were: 122.14, 155.14, 198.43 and; 247.43 Wcm2, respectively. The mean values of permeability coefficients on the 21st day of culture for 6-carboxyfluorescein and rhodamin B were 3.87 +/-0.10 x 10(-6)cm/s and 3.65 +/- 0.06 x 10(-6)cm/s, respectively. We state that the in vitro bovine corneal epithelial primary culture model is useful for ocular studies.

Anthocyanin-rich Aronox extract from Aronia melanocarpa E protects against 7beta-hydroxycholesterol-induced apoptosis of endothelial cells.

AIMS: It has been previously reported that dietary polyphenolic compounds have a positive effect in cardiovascular diseases, although the underlying mechanisms remain unknown. In this study, the effects of Aronox, an anthocyanin-rich extract from Aronia melanocarpa E, on human umbilical vein endothelial cell (HUVEC) apoptosis was investigated. METHODS: Apoptosis was measured in HUVEC pretreated with Aronox and than treated with 7beta-hydroxycholesterol (20 microg/ml). For the evaluation of apoptosis we used the cell binding of annexin V, the propidium iodide uptake method and the TUNEL assay. We also measured the generation of reactive oxygen species (ROS) in the cells, using fluorescent probe 2',7'-dichlorofluorescein acetate. Moreover, alteration of the mitochondrial membrane potential with subsequent cytochrome c release, activation of caspase-3, and the level of anti-apoptotic Bcl-2 were investigated. RESULTS: Aronox significantly decreased 7beta-hydroxycholesterol-induced apoptosis and ROS generation, and ameliorated the collapse of the mitochondrial transmembrane potential with subsequent inhibition of cytochrome c release. Furthermore, down-regulation of Bcl-2 and up-regulation of caspase-3 activation were reversed by Aronox. CONCLUSION: The protective action of the extract against apoptosis in endothelial cells may contribute to the potential benefits drawn from consumption of plant polyphenols.

Is there an association between angiotensin-converting enzyme gene polymorphism and functional activation of monocytes and macrophage in young patients with essential hypertension?

BACKGROUND: This study was undertaken to determine whether the phenotype of monocytes and monocyte-derived macrophages is more proatherogenic in young persons with arterial hypertension and whether this phenotype is affected by smoking or polymorphism of the angiotensin-converting enzyme (ACE) gene. METHODS: We enrolled 40 young patients (24.1 +/- 4.7 years) with previously untreated arterial hypertension and 40 age-matched healthy controls. There were 20 smokers and 20 non-smokers in each group. RESULTS: In the hypertensive group, we found enhanced monocyte expression of CD11a (P < 0.001), reduced expression of CD49d (P < 0.001) and CD62L (P < 0.005), greater oxidative stress in resting and phorbol-12-mistrate-13-acetate-stimulated monocytes (P < 0.001), enhanced adhesion of monocytes to endothelial cells (P < 0.001), greater expression of CD36 on monocyte-derived macrophages (P < 0.001), and enhanced production of reactive oxygen species by resting and phorbol-12-mistrate-13-acetate-stimulated macrophages (P < 0.001). Cigarette smoking by hypertensive patients was associated with enhanced (P < 0.002) CD11a expression. There were no associations of ACE gene polymorphism with cellular expression or reactive oxygen species production studied among hypertensive patients. Only CD62L expression in DD homozygote participants was higher (P < 0.039) than in II homozygote participants. CONCLUSIONS: It is concluded that arterial hypertension affects the function of monocytes/macrophages in young persons. Polymorphism of the ACE gene is without effect on the functional activation of monocytes and macrophages.

Effect of Lactobacillus plantarum 299v on cardiovascular disease risk factors in smokers.

BACKGROUND: The short-chain fatty acids formed in the human colon by the bacterial fermentation of fiber may have an antiinflammatory effect, may reduce insulin production, and may improve lipid metabolism. We previously showed in hypercholesterolemic patients that supplementation with the probiotic bacteria Lactobacillus plantarum 299v significantly lowers concentrations of LDL cholesterol and fibrinogen. OBJECTIVE: We determined the influence of a functional food product containing L. plantarum 299v on lipid profiles, inflammatory markers, and monocyte function in heavy smokers. DESIGN: Thirty-six healthy volunteers (18 women and 18 men) aged 35-45 y participated in a controlled, randomized, double-blind trial. The experimental group drank 400 mL/d of a rose-hip drink containing L. plantarum 299v (5 x 10(7) colony-forming units/mL); the control group consumed the same volume of product without bacteria. The experiment lasted 6 wk and entailed no changes in lifestyle. RESULTS: Significant decreases in systolic blood pressure (P < 0.000), leptin (P < 0.000), and fibrinogen (P < 0.001) were recorded in the experimental group. No such changes were observed in the control group. Decreases in F(2)-isoprostanes (37%) and interleukin 6 (42%) were also noted in the experimental group in comparison with baseline. Monocytes isolated from subjects treated with L. plantarum showed significantly reduced adhesion (P < 0.001) to native and stimulated human umbilical vein endothelial cells. CONCLUSION: L. plantarum administration leads to a reduction in cardiovascular disease risk factors and could be useful as a protective agent in the primary prevention of atherosclerosis in smokers.

Butyrate inhibits cytokine-induced VCAM-1 and ICAM-1 expression in cultured endothelial cells: the role of NF-kappaB and PPARalpha.

Adhesion and migration of leukocytes into the surrounding tissues is a crucial step in inflammation, immunity, and atherogenesis. Expression of cell adhesion molecules by endothelial cells plays a leading role in this process. Butyrate, a natural short-chain fatty acid produced by bacterial fermentation of dietary fiber, has been attributed with anti-inflammatory activity in inflammatory bowel disease. Butyrate in vitro is active in colonocytes and several other cell types. We have studied the effect of butyrate on expression of endothelial leukocyte adhesion molecules by cytokine-stimulated human umbilical vein endothelial cells (HUVEC). Pretreatment of HUVEC with butyrate-inhibited tumor necrosis factor-alpha (TNFalpha)-induced expression of vascular cell adhesion molecule-1 (VCAM-1) and intracellular cell adhesion molecule-1 (ICAM-1) in a time and concentration-dependent manner. Butyrate at 10 mM/L inhibited interleukin-1 (IL-1)-stimulated VCAM-1 and ICAM-1 expression. The effect of butyrate on cytokine-stimulated VCAM-1 expression was more pronounced than in the case of ICAM-1. Butyrate decreased TNFalpha-induced expression of mRNA for VCAM-1 and ICAM-1. Suppressed expression of VCAM-1 and ICAM-1 was associated with reduced adherence of monocytes and lymphocytes to cytokine-stimulated HUVEC. Butyrate inhibited TNFalpha-induced activation of nuclear factor-kappaB (NF-kappaB) in HUVEC. Finally, butyrate enhanced peroxisome proliferator-activated receptor-alpha (PPARalpha) expression in HUVEC. These results demonstrate that butyrate may have anti-inflammatory properties not only in colonocytes but also in endothelial cells. The anti-inflammatory and (perhaps) antiatherogenic properties of butyrate may partly be attributed to an effect on activation of NF-kappaB and PPARalpha and to the associated expression of VCAM-1 and ICAM-1. The present findings support further investigations on the therapeutic benefits of butyrate in several pathological events involving leukocyte recruitment.

Protective properties of artichoke (Cynara scolymus) against oxidative stress induced in cultured endothelial cells and monocytes.

It is currently believed that oxidative stress and inflammation play a significant role in atherogenesis. Artichoke extract exhibits hypolipemic properties and contains numerous active substances with antioxidant properties in vitro. We have studied the influence of aqueous and ethanolic extracts from artichoke on intracellular oxidative stress stimulated by inflammatory mediators (TNFalpha and LPS) and ox-LDL in endothelial cells and monocytes. Oxidative stress which reflects the intracellular production of reactive oxygen species (ROS) was followed by measuring the oxidation of 2', 7'-dichlorofluorescin (DCFH) to 2', 7'-dichlorofluorescein (DCF). Agueous and ethanolic extracts from artichoke were found to inhibit basal and stimulated ROS production in endothelial cells and monocytes in dose dependent manner. In endothelial cells, the ethanolic extract (50 microg/ml) reduced ox-LDL-induced intracellular ROS production by 60% (p<0,001) while aqueous extract (50 microg/ml) by 43% (p<0,01). The ethanolic extract (50 microg/ml) reduced ox-LDL-induced intracellular ROS production in monocytes by 76% (p<0,01). Effective concentrations (25-100 microg/ml) were well below the cytotoxic levels of the extracts which started at 1 mg/ml as assessed by LDH leakage and trypan blue exclusion. Penetration of some active substances into the cells was necessary for inhibition to take place as juged from the effect of preincubation time. These results demonstrate that artichoke extracts have marked protective properties against oxidative stress induced by inflammatory mediators and ox-LDL in cultured endothelial cells and monocytes.

[Atherosclerosis: a chronic inflammatory diseases]. / Miazdzyca jako przewlekla choroba zapalna.

In spite of years of intense investigations, the pathogenesis of atherosclerosis awaits final elucidation and its complications continue to challenge contemporary medicine. It is generally believed that atherosclerosis is the result of chronic and evolving fibroproliferative inflammatory response against harmful factors acting on the vascular wall. This work is a concise review of mechanisms participating in the initiation, evolution and complications of atherosclerosis. Endothelial cell dysfunction is discussed with emphasis on the role of endothelial adhesion molecules. Attention is focused on the function of monocytes/macrophages and lymphocytes as mediators of inflammation and immune response.

Chronic intake of potato chips in humans increases the production of reactive oxygen radicals by leukocytes and increases plasma C-reactive protein: a pilot study.

BACKGROUND: Relatively high concentrations of acrylamide in commonly ingested food products, such as French fries, potato chips, or cereals, may constitute a potential risk to human health. OBJECTIVE: The objective of this pilot study was to investigate the possible connection between chronic ingestion of acrylamide-containing potato chips and oxidative stress or inflammation. DESIGN: Fourteen healthy volunteers (mean age: 35 y; 8 women and 6 smokers of >20 cigarettes/d) were given 160 g of potato chips containing 157 microg [corrected] acrylamide daily for 4 wk. RESULTS: An increase in acrylamide-hemoglobin adducts in blood was found in all the study subjects, with a mean of 43.1 pmol x L(-1) x g(-1) hemoglobin (range: 27-76; P < 0.01) in nonsmokers and 59.0 pmol x L(-1) x g(-1) hemoglobin (range: 43-132; P < 0.05) in smokers. Concurrently, a significant increase (P < 0.01) in the oxidized LDL, high-sensitivity interleukin-6, high-sensitivity C-reactive protein, and gamma-glutamyltransferase concentrations was observed in both smokers and nonsmokers. A significant increase in reactive oxygen radical production by monocytes, lymphocytes, and granulocytes and an increase in CD14 expression in macrophages (P < 0.001) were found after intake of potato chips. Twenty-eight days from the discontinuation of the experiment, the variables under study decreased to some extent. It has been shown also that acrylamide increases the production of reactive oxygen species in isolated human monocyte-macrophages in vitro and decreases the cellular glutathione concentration. CONCLUSION: These novel findings seem to indicate that chronic ingestion of acrylamide-containing products induces a proinflammatory state, a risk factor for progression of atherosclerosis.

[The role of modified oxidation of low density lipoprotein in pathognesis of atherosclerosis]. / Rola zmodyfikowanych oksydacyjnie lipoprotein malej gestosci w patogenezie miazdzycy.

The precise mechanisms of LDL oxidation in vivo are not well-known but the presence of several enzymes and agents capable of modifying LDL particles was noted in arterial wall. These reactive agents modify lipid, protein as well as antioxidant component of the LDL particles. Postsecretory modification in LDL structure trigger its atherogenic potential. LDL particles retained in the artery wall interact with the various forms of proteoglycans in the extracellular matrix, that increases the resident time of LDL in endothelial space and allows extensive modification. The modified forms of LDL are able to activate intimal cells and to trigger various inflammatory signals. In turn, activated intimal cells can secrete enzymes and agents capable of modifying LDL. These processes can initiate and maintain a vicious circle in the intima and lead to lesion progression.