Balazs Debreceni

Antioxidant and Anti-Inflammatory Effects in RAW264.7 Macrophages of Malvidin, a Major Red Wine Polyphenol

Background Red wine polyphenols can prevent cardiovascular and inflammatory diseases. Resveratrol, the most extensively studied constituent, is unlikely to solely account for these beneficial effects because of its rather low abundance and bioavailability. Malvidin is far the most abundant polyphenol in red wine; however, very limited data are available about its effect on inflammatory processes and kinase signaling pathways. Methods & Findings The present study was carried out by using RAW 264.7 macrophages stimulated by bacterial lipopolysaccharide in the presence and absence of malvidin. From the cells, activation of nuclear factor-kappaB, mitogen-activated protein kinase, protein kinase B/Akt and poly ADP-ribose polymerase, reactive oxygen species production, mitogen-activated protein kinase phosphatase-1 expression and mitochondrial depolarization were determined. We found that malvidin attenuated lipopolysaccharide-induced nuclear factor-kappaB, poly ADP-ribose polymerase and mitogen-activated protein kinase activation, reactive oxygen species production and mitochondrial depolarization, while upregulated the compensatory processes; mitogen-activated protein kinase phosphatase-1 expression and Akt activation. Conclusions These effects of malvidin may explain the previous findings and at least partially account for the positive effects of moderate red wine consumption on inflammation-mediated chronic maladies such as obesity, diabetes, hypertension and cardiovascular disease.

The Role of Homocysteine-Lowering B-Vitamins in the Primary Prevention of Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of mortality in the Western world. The effort of research should aim at the primary prevention of CVD. Alongside statin therapy, which is maintained to be an effective method of CVD prevention, there are alternative methods such as vitamin B substitution therapy with folic acid (FA), and vitamins B12 and B6 . B-vitamins may inhibit atherogenesis by decreasing the plasma level of homocysteine (Hcy)-a suspected etiological factor for atherosclerosis-and by other mechanisms, primarily through their antioxidant properties. Although Hcy-lowering vitamin trials have failed to demonstrate beneficial effects of B-vitamins in the prevention of CVD, a meta-analysis and stratification of a number of large vitamin trials have suggested their effectiveness in cardiovascular prevention (CVP) in some aspects. Furthermore, interpretation of the results from these large vitamin trials has been troubled by statin/aspirin therapy, which was applied along with the vitamin substitution, and FA fortification, both of which obscured the separate effects of vitamins in CVP. Recent research results have accentuated a new approach to vitamin therapy for CVP. Studies undertaken with the aim of primary prevention have shown that vitamin B substitution may be effective in the primary prevention of CVD and may also be an option in the secondary prevention of disease if statin therapy is accompanied by serious adverse effects. Further investigations are needed to determine the validity of vitamin substitution therapy before its introduction in the protocol of CVD prevention.

Regulation of MKP-1 expression and MAPK activation by PARP-1 in oxidative stress: A new mechanism for the cytoplasmic effect of PARP-1 activation

Previously, it was suggested that the release of nuclearly formed ADP-ribose polymers or ADP-ribosylated proteins could be responsible for the cytosolic and mitochondrial effects of poly(ADP-ribose) polymerase (PARP)-1 activation in oxidative stress. In this report, we provide a novel alternative mechanism. We found that reactive oxygen species-activated PARP-1 regulated the activation of JNK and p38 mitogen-activated protein kinases (MAPKs) because inhibition of PARP-1 by pharmacons, small interfering RNA silencing of PARP-1 expression, or the transdominant expression of enzymatically inactive PARP-1 resulted in the inactivation of these MAPKs. This regulation was achieved by increased expression and enlarged cytoplasmic localization of MAPK phosphatase-1 (MKP-1) upon PARP-1 inhibition in oxidative stress because changes in MKP-1 expression were reflected in the phosphorylation states of JNK and p38. Furthermore, we found that in MKP-1-silenced cells, PARP inhibition was unable to exert its protective effect, indicating the pivotal roles of JNK and p38 in mediating the oxidative-stress-induced cell death as well as that of increased MKP-1 expression in mediating the protective effect of PARP inhibition. We suggest that regulation of a protein that can directly influence cytoplasmic signaling cascades at the expression level represents a novel mechanism for the cytoplasmic action of PARP-1 inhibition.

Why Do Homocysteine‐Lowering B Vitamin and Antioxidant E Vitamin Supplementations Appear To Be Ineffective in the Prevention of Cardiovascular Diseases?

Homocysteine has been established as a serious, independent risk factor for atherosclerosis. An elevated plasma homocysteine concentration is accompanied by increased cardiovascular risk; therefore, it can be assumed that lowering the plasma homocysteine level results in a decreased risk. Vitamin B complex (folic acid, and vitamins B6 and B12) substitution therapy decreases the plasma homocysteine level, inhibits oxidative stress, and ameliorates some biochemical and clinical parameters that indicate the progression of atherosclerosis. Vitamin E administration may also reduce atherogenesis through its antioxidant effect. The effectiveness of B and E vitamin substitution in decreasing cardiovascular risk has been suggested by cohort as well as prospective and retrospective studies undertaken during the last two decades. On the other hand, recent large, randomized clinical trials did not substantiate a beneficial effect of homocysteine-lowering B vitamin supplementation or vitamin E antioxidant therapies in reducing cardiovascular risk in humans. We analyzed eight B vitamin and four E vitamin trials from a critical point of view, and in this article we reviewed and commented on their results and focused on the contradictions found in them. We showed that the possible factors implicated in the failure of vitamin therapies included inappropriate designs. The protocols neglected an essential fact: that the impact of some confounding factors, such as concomitant use of statins, acetylsalicylic acid, folic acid, and other drugs, might have led to bias and an inappropriate interpretation of the data. The cardiovascular protective and preventive effects of statins and aspirin might have reduced or abolished the possibility of observing a difference in the number of events between the vitamin and placebo groups for the clinical endpoints. We concluded that the vitamin preventive effect on cardiovascular disease may not be rejected in reference to the negative trial evidence.

Suppressing LPS-induced early signal transduction in macrophages by a polyphenol degradation product: a critical role of MKP-1

Macrophages represent the first defense line against bacterial infection and therefore, play a crucial role in early inflammatory response. In this study, we investigated the role of MAPKs and MKP‐1 activation in regulation of an early inflammatory response in RAW 264.7 macrophage cells. We induced the inflammatory response by treating the macrophages with LPS and inhibited an early inflammatory response by using ferulaldehyde, a water‐soluble end‐product of dietary polyphenol degradation that we found previously to exert its beneficial anti‐inflammatory effects during the early phase of in vivo inflammation. We found that LPS‐induced ROS and nitrogen species formations were reduced by ferulaldehyde in a concentration‐dependent manner, and ferulaldehyde protected mitochondria against LPS‐induced rapid and massive membrane depolarization. LPS induced early suppression of MKP‐1, which was accompanied by activation of JNK, ERK, and p38 MAPK. By reversing LPS‐induced early suppression of MKP‐1, ferulaldehyde diminished MAPK activation, thereby inhibiting NF‐κB activation, mitochondrial depolarization, and ROS production. Taken together, our data suggest that ferulaldehyde exerts its early anti‐inflammatory effect by preserving the mitochondrial membrane integrity and shifting the expression of MKP‐1 forward in time in macrophages.

Metabolism of carnitine in phenylacetic acid-treated rats and in patients with phenylketonuria

The effect of metabolites accumulating in phenylketonuria (PKU) was investigated on carnitine metabolism in rats and in patients with PKU. Of phenylacetic acid (PEAA), phenylpyruvic acid and homogentisic acid the PEAA was found to be the most effective in inhibiting carnitine biosynthesis in rats. Following 60 min, a single intraperitoneal dose of PEAA the relative conversion rate, i. e. the hydroxylation, of tracer [Me-(3)H]butyrobetaine to [Me-(3)H]carnitine decreased from 62.2+/-6.00% to 39.4+/-5.11% (means+/-S.E.M., P<0.01) in the liver, in the only organ doing this conversion in rats. The conversion of loading amount of unlabeled butyrobetaine to carnitine was also markedly reduced. The impaired hydroxylation of butyrobetaine was reflected by a reduced free and total carnitine levels in the liver and a reduced total carnitine concentration in the plasma. PEAA decreased the hepatic level of glutamic acid and alpha-ketoglutaric acid (alpha-KG), suggesting a mechanism for the reduced flux through the butyrobetaine hydroxylase enzyme, because alpha-KG is an obligatory co-enzyme. In the plasma and urine of PKU patients on unrestricted diet, markedly decreased total carnitine levels were detected. In the liver of PEAA-treated rats and urine of PKU patients, a novel carnitine derivative, phenacetyl-carnitine was verified by HPLC and gas chromatography-mass spectrometry.

BGP-15 protects against oxidative stress- or lipopolysaccharide-induced mitochondrial destabilization and reduces mitochondrial production of reactive oxygen species

Reactive oxygen species (ROS) play a critical role in the progression of mitochondria-related diseases. A novel insulin sensitizer drug candidate, BGP-15, has been shown to have protective effects in several oxidative stress-related diseases in animal and human studies. In this study, we investigated whether the protective effects of BGP-15 are predominantly via preserving mitochondrial integrity and reducing mitochondrial ROS production. BGP-15 was found to accumulate in the mitochondria, protect against ROS-induced mitochondrial depolarization and attenuate ROS-induced mitochondrial ROS production in a cell culture model, and also reduced ROS production predominantly at the complex I-III system in isolated mitochondria. At physiologically relevant concentrations, BGP-15 protected against hydrogen peroxide-induced cell death by reducing both apoptosis and necrosis. Additionally, it attenuated bacterial lipopolysaccharide (LPS)-induced collapse of mitochondrial membrane potential and ROS production in LPS-sensitive U-251 glioma cells, suggesting that BGP-15 may have a protective role in inflammatory diseases. However, BGP-15 did not have any antioxidant effects as shown by in vitro chemical and cell culture systems. These data suggest that BGP-15 could be a novel mitochondrial drug candidate for the prevention of ROS-related and inflammatory disease progression.

Activation of mitochondrial fusion provides a new treatment for mitochondria-related diseases

Graphical abstract Figure. No Caption available. Abstract Mitochondria fragmentation destabilizes mitochondrial membranes, promotes oxidative stress and facilitates cell death, thereby contributing to the development and the progression of several mitochondria‐related diseases. Accordingly, compounds that reverse mitochondrial fragmentation could have therapeutic potential in treating such diseases. BGP‐15, a hydroxylamine derivative, prevents insulin resistance in humans and protects against several oxidative stress‐related diseases in animal models. Here we show that BGP‐15 promotes mitochondrial fusion by activating optic atrophy 1 (OPA1), a GTPase dynamin protein that assist fusion of the inner mitochondrial membranes. Suppression of Mfn1, Mfn2 or OPA1 prevents BGP‐15‐induced mitochondrial fusion. BGP‐15 activates Akt, S6K, mTOR, ERK1/2 and AS160, and reduces JNK phosphorylation which can contribute to its protective effects. Furthermore, BGP‐15 protects lung structure, activates mitochondrial fusion, and stabilizes cristae membranes in vivo determined by electron microscopy in a model of pulmonary arterial hypertension. These data provide the first evidence that a drug promoting mitochondrial fusion in in vitro and in vivo systems can reduce or prevent the progression of mitochondria‐related disorders.

Role of vitamins in cardiovascular health and disease

Cardiovascular disease (CVD) is the leading cause of mortality around the world. The prevention of CVD is a main goal of health care. Vitamins, especially those with antioxidant potency, may have a role in the prevention of and therapy for CVD. Antioxidant vitamins, vitamin C, vitamin E, and carotenoids are able to decrease the rate of oxidative stress, which may have a principal role in the pathogenesis of atherosclerosis and CVD. Vitamin B 6 , vitamin B 12 , and folic acid, as well as vitamin D, also contribute to maintenance of cardiovascular health and can induce cardioprotective effects. Although most of the randomized controlled trials on vitamins failed to show the benefit of vitamin supplementation for cardiovascular outcomes, a number of observational and cohort studies, meta-analyses, and stratified analyses of large vitamin trials appeared to show an effect in some aspects of cardiovascular prevention. Moreover, many of the vitamin trials for secondary prevention are biased by use of vitamins and drugs effective for cardiovascular prevention; therefore, the conclusions drawn from them supporting the effectiveness of vitamin substitution for the prevention of CVD may be inappropriate. To summarize, there are abundant data suggesting the role of vitamins in cardiovascular health and in the primary prevention of CVD; however, examinations using new concepts and new study designs are needed to establish the effectiveness of vitamin supplementation in the therapy for