On the molecular pharmacology of resveratrol on oxidative burst inhibition in professional phagocytes

Quercetin inhibits neutrophil extracellular traps release and their cytotoxic effects on A549 cells, as well the release and enzymatic activity of elastase and myeloperoxidase

Abstract Neutrophil extracellular traps (NETs) were first reported as a microbicidal strategy for activated neutrophils. Through an immunologic response against several stimuli, neutrophils release their DNA together with proteins from granules, nucleus, and cytoplasm (e.g., elastase and myeloperoxidase). To date, NETs have been implicated in tissue damage during intense inflammatory processes, mainly when their release is dependent on oxygen radical generation. Flavonoids are antioxidant and anti-inflammatory agents; of these, quercetin is commonly found in our daily diet. Therefore, quercetin could exert some protective activity against tissue damage induced by NETs. In our in vitro assays, quercetin reduced NETs, myeloperoxidase (MPO), and elastase release from neutrophils stimulated with phorbol 12-myristate 13-acetate (PMA). The activity of these enzymes also decreased in the presence of quercetin. Quercetin also reduced the cytotoxic effect of NETs on alveolar cells (A549 cell line). Further, in silico assays indicated favorable interactions between quercetin and NET proteins (MPO and elastase). Overall, our results demonstrate that quercetin decreases deleterious cellular effects of NETs by reducing their release from activated neutrophils, and diminishing the enzymatic activity of MPO and elastase, possibly through direct interaction.

Complex interactions between nicotine and resveratrol in the Drosophila melanogaster wing spot test

Nicotine (NIC) and resveratrol (RES) are chemicals in tobacco and wine, respectively, that are widely consumed concurrently worldwide. NIC is an alkaloid known to be toxic, addictive and to produce oxidative stress, while RES is thought of as an antioxidant with putative health benefits. Oxidative stress can induce genotoxic damage, yet few studies have examined whether NIC is genotoxic in vivo. In vitro studies have shown that RES can ameliorate deleterious effects of NIC. However, RES has been reported to have both antioxidant and pro-oxidant effects, and an in vivo study reported that 0.011 mM RES was genotoxic. We used the Drosophila melanogaster wing spot test to determine whether NIC and RES, first individually and then in combination, were genotoxic and/or altered the cell division. We hypothesized that RES would modulate NIC’s effects. NIC was genotoxic in the standard (ST) cross in a concentration-independent manner, but not genotoxic in the high bioactivation (HB) cross. RES was not genotoxic in either the ST or HB cross at the concentrations tested. We discovered a complex interaction between NIC and RES. Depending on concentration, RES was protective of NIC’s genotoxic damage, RES had no interaction with NIC, or RES had an additive or synergistic effect, increasing NIC’s genotoxic damage. Most NIC, RES, and NIC/RES combinations tested altered the cell division in the ST and HB crosses. Because we used the ST and HB crosses, we demonstrated that genotoxicity and cell division alterations were modulated by the xenobiotic metabolism. These results provide evidence of NIC’s genotoxicity in vivo at specific concentrations. Moreover, NIC’s genotoxicity can be modulated by its interaction with RES in a complex manner, in which their interaction can lead to either increasing NIC’s damage or protecting against it.

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Nicotine was genotoxic at specific concentrations in the Drosophila wing spot test.

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Resveratrol protected against nicotine’s genotoxic effects at some concentrations.

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Resveratrol increased nicotine’s genotoxicity at specific concentrations.

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Nicotine and resveratrol have a complex interaction in vivo.

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Studying chemicals in combination in vivo may uncover unexpected interactions.

Biogenesis of Iron-Sulfur Clusters and Their Role in DNA Metabolism

Iron–sulfur (Fe/S) clusters (ISCs) are redox-active protein cofactors that their synthesis, transfer, and insertion into target proteins require many components. Mitochondrial ISC assembly is the foundation of all cellular ISCs in eukaryotic cells. The mitochondrial ISC cooperates with the cytosolic Fe/S protein assembly (CIA) systems to accomplish the cytosolic and nuclear Fe/S clusters maturation. ISCs are needed for diverse cellular functions, including nitrogen fixation, oxidative phosphorylation, mitochondrial respiratory pathways, and ribosome assembly. Recent research advances have confirmed the existence of different ISCs in enzymes that regulate DNA metabolism, including helicases, nucleases, primases, DNA polymerases, and glycosylases. Here we outline the synthesis of mitochondrial, cytosolic and nuclear ISCs and highlight their functions in DNA metabolism.

Neutrophils in respiratory syncytial virus infection: From harmful effects to therapeutic opportunities

Respiratory syncytial virus (RSV) is an important infectious agent in infants and young children. In most cases, RSV infection only causes mild disease, but in some, it requires invasive ventilation. Although antiviral drugs are obvious candidates to treat viral illness, and some have shown antiviral effects in humans, antivirals such as GS-5806, ALX-0171 and ALS-8176 have not yet met their expectations. Since the inappropriate or dysregulated immune response against RSV leads to harmful immune pathology, a robust immune cascade is probably underway by the time patients reach the hospital. RSV infection is associated with a strong neutrophil influx into the airway. It not clear if these cells contribute to antiviral defence or to lung pathology. This article discusses the protective and harmful roles of neutrophils during RSV infection and provides an overview of mechanisms by which neutrophil function could be targeted to prevent tissue injury and preserve homeostasis.

Resveratrol suppresses neutrophil activation via inhibition of Src family kinases to attenuate lung injury

The natural stilbenoid, Resveratrol (RSV; 3,5,4'-trihydroxystilbene) has been shown to have beneficial effects on inflammatory diseases as well as cancer, neurodegenerative diseases, and cardiovascular disorders. The underlying mechanism by which RSV affects neutrophil activation has yet to be fully elucidated. In this study, we tested the hypothesis that RSV modulates the inflammatory activities of formyl-Met-Leu-Phe-stimulated human neutrophils. We employed a well-established isolated-neutrophil model to investigate the effects of RSV on neutrophil functions and the underlying mechanism of signaling transduction. The lipopolysaccharide-induced ALI murine model was employed to evaluate the therapeutic effects of RSV. Experiment results demonstrate that RSV reduces respiratory burst, degranulation, integrin expression, and cell adhesion in activated neutrophils in dose-dependent manners. RSV inhibited phosphorylation of Src family kinases (SFKs) and reduced their enzymatic activities. Moreover, RSV and a selective inhibitor of SFKs (PP2) reduced the phosphorylation of Bruton's tyrosine kinase and Vav. There results indicated that the inhibitory effects of RSV are mediated through the inhibition of the SFKs-Btk-Vav pathway. This study also revealed that RSV attenuates endotoxin-induced lung injury. We surmise that the therapeutic effects of RSV on ALI may derive from its anti-neutrophilic inflammation function and free radical-scavenging effects.

The Bioprotective Effects of Polyphenols on Metabolic Syndrome against Oxidative Stress: Evidences and Perspectives

Polyphenols are the general designation of various kinds of phytochemicals, mainly classified as flavonoids and nonflavonoids. Polyphenolic compounds have been confirmed to exhibit numerous bioactivities and potential health benefits both in vivo and in vitro. Dietary polyphenols have been shown to significantly alleviate several manifestations of metabolic syndrome, namely, central obesity, hypertension, dyslipidemia, and high blood sugar. This review is aimed at discussing the bioprotective effects and related molecular mechanisms of polyphenols, mainly by increasing antioxidant capacity or oxygen scavenging capacity. Polyphenols can exert their antioxidative activity by balancing the organic oxidoreductase enzyme system, regulating antioxidant responsive signaling pathways, and restoring mitochondrial function. These data are helpful for providing new insights into the potential biological effects of polyphenolic compounds and the development of future antioxidant therapeutics.

Iron-sulfur clusters in nucleic acid metabolism: Varying roles of ancient cofactors

Despite their relative simplicity, iron-sulfur clusters have been omnipresent as cofactors in myriad cellular processes such as oxidative phosphorylation and other respiratory pathways. Recent research advances confirm the presence of different clusters in enzymes involved in nucleic acid metabolism. Iron-sulfur clusters can therefore be considered hallmarks of cellular metabolism. Helicases, nucleases, glycosylases, DNA polymerases and transcription factors, among others, incorporate various types of clusters that serve differing roles. In this chapter, we review our current understanding of the identity and functions of iron-sulfur clusters in DNA and RNA metabolizing enzymes, highlighting their importance as regulators of cellular function.

Resveratrol prevents nanoparticles-induced inflammation and oxidative stress via downregulation of PKC-α and NADPH oxidase in lung epithelial A549 cells

Background

Exposure to carbon black nanoparticles (CBNPs), a well-known industrial production, promotes pulmonary toxicity through inflammation and oxidative stress. Recent studies show that some polyphenols exert their antioxidant properties through regulation of protein kinase C-α (PKC-α) and NADPH oxidase (Nox) signaling. Resveratrol, a dietary polyphenol in fruits, possesses various health beneficial effects including anti-inflammatory and antioxidative properties. In this study, we aimed to elucidate the involvement of PKC-α and Nox in CBNPs-induced inflammation and oxidative stress, and to investigate the protective effects of resveratrol on CBNP-induced inflammation and oxidative stress in human lung epithelial A549 cells.

Methods

The production of reactive oxygen species (ROS) and the change of mitochondrial membrane potential (ΔΨm) were measured by flow cytometry. Nitric oxide (NO) was measured using the Griess reagent, and prostaglandin E₂ (PGE₂) production was detected by ELISA, while protein expressions were measured by Western blotting analysis.

Results

In lung epithelial A549 cells, CBNPs significantly enhanced oxidative stress by upregulation of Nox2 and membrane expression of p67^phox accompanied with increase of ROS production. CBNPs also increased inflammatory factors, including iNOS, COX-2, NO and PGE₂. However, resveratrol attenuated the above effects induced by CBNPs in A549 cells; additionally, CBNPs-induced activation of PKC-α was observed. We found that PKC-α inhibitor (Gö6976) could attenuate CBNPs-induced inflammation by down-regulation of ROS, NO and PGE₂ production in A549 cells, suggesting PKC-α might be involved in CBNPs-induced oxidative stress and inflammation. Our results also found resveratrol was able to inhibit protein expression of PKC-α induced by CBNPs. Moreover, ROS scavenger (NAC) and Nox inhibitor (DPI) attenuated CBNPs-induced expressions of iNOS and COX-2. DPI could also attenuate CBNPs-induced ROS, NO and PGE₂ production.

Conclusions

Resveratrol attenuated CBNPs-induced oxidative and inflammatory factors in lung epithelial A549 cells, at least in part via inhibiting PKC-α- and Nox-related signaling.

Pharmacological intervention with oxidative burst in human neutrophils

In this study we investigated the effect of five therapeutically used drugs and four natural polyphenolic compounds on the mechanism of oxidative burst of human neutrophils concerning their participation in the generation of reactive oxygen species (ROS). The compounds investigated decreased the oxidative burst of whole blood in the rank order of potency: N-feruloylserotonin > quercetin > curcumin > arbutin > dithiaden > carvedilol. The generation of intracellular reactive oxygen species in isolated neutrophils decreased in the same rank order, while carvedilol was ineffective. Scavenging of extracellular oxygen radicals followed the rank order of potency: N-feruloylserotonin > curcumin > quercetin > dithiaden. Arbutin and carvedilol had no effect. All compounds tested increased the activity of caspase-3 in cell-free system indicating a positive effect on apoptosis of neutrophils. Activation of protein kinase C was significantly decreased by dithiaden, curcumin, quercetin and N-feruloylserotonin. Carvedilol, dithiaden, quercetin and arbutin reduced activated neutrophil myeloperoxidase release more significantly compared with their less pronounced effect on superoxide generation The presented results are indicative of pharmacological intervention with neutrophils in pathological processes. Of particular interest was the effect of natural compounds. Intracellular inhibition of oxidative burst in isolated neutrophils by the drugs tested and natural antioxidants has to be further analysed since ROS play an important role in immunological responses of neutrophils.

Early Subretinal Allograft Rejection Is Characterized by Innate Immune Activity

Successful subretinal transplantation is limited by considerable early graft loss despite pharmacological suppression of adaptive immunity. We postulated that early innate immune activity is a dominant factor in determining graft survival and chose a nonimmunosuppressed mouse model of retinal pigment epithelial (RPE) cell transplantation to explore this. Expression of almost all measured cytokines by DH01 RPE cells increased significantly following graft preparation, and the neutrophil chemoattractant KC/GRO/CINC was most significantly increased. Subretinal allografts of DH01 cells (C57BL/10 origin) into healthy, nonimmunosuppressed C57BL/6 murine eyes were harvested and fixed at 1, 3, 7, and 28 days postoperatively and subsequently cryosectioned and stained. Graft cells were detected using SV40 large T antigen (SV40T) immunolabeling and apoptosis/necrosis by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Sections were also immunolabeled for macrophage (CD11b and F4/80), neutrophil (Gr1 Ly-6G), and T-lymphocyte (CD3-ɛ) infiltration. Images captured with an Olympus FV1000 confocal microscope were analyzed using the Imaris software. The proportion of the subretinal bolus comprising graft cells (SV40T+) was significantly (p < 0.001) reduced between postoperative day (POD) 3 (90 ± 4%) and POD 7 (20 ± 7%). CD11b+, F4/80+, and Gr1 Ly-6G+ cells increased significantly (p < 0.05) from POD 1 and predominated over SV40T+ cells by POD 7. Colabeling confocal microscopic analysis demonstrated graft engulfment by neutrophils and macrophages at POD 7, and reconstruction of z-stacked confocal images confirmed SV40T inside Gr1 Ly-6G+ cells. Expression of CD3-ɛ was low and did not differ significantly between time points. By POD 28, no graft cells were detectable and few inflammatory cells remained. These studies reveal, for the first time, a critical role for innate immune mechanisms early in subretinal graft rejection. The future success of subretinal transplantation will require more emphasis on techniques to limit innate immune-mediated graft loss, rather than focusing exclusively on suppression of the adaptive immune response.

On the pharmacology of oxidative burst of human neutrophils

The effect of three therapeutically used drugs and five polyphenolic compounds on the mechanism of oxidative burst was compared in whole blood and isolated neutrophils at cellular and molecular level. In 10 microM concentration, the compounds investigated decreased the oxidative burst of whole blood in the rank order of potency: N-feruloylserotonin (N-f-5HT) > curcumin (CUR) > quercetin (QUER) > arbutin (ARB) > resveratrol (RES) > dithiaden (DIT) > carvedilol (CARV) > brompheniramine (BPA). The ratio between the percentage inhibition of extracellular versus intracellular chemiluminescence (CL) followed the rank order QUER > N-f-5HT > RES > CUR > DIT and is indicative of the positive effect of the compounds tested against oxidative burst of neutrophils, demonstrating suppression of reactive oxygen species extracellularly with minimal alteration of intracellular reactive oxygen species (ROS). Activation of protein kinase C was significantly decreased by DIT, CUR, QUER and N-f-5HT. CARV, DIT, QUER and ARB reduced activated neutrophil myeloperoxidase release more significantly compared with the effect on superoxide anion generation. All compounds tested increased the activity of caspase-3 in cell-free system. It is suggested that other regulatory mechanisms than protein kinase C might participate in the inhibition of neutrophil activation with the compounds tested. Different mechanisms are concerned in controlling the assembly of NADPH oxidase and the regulatory role of calcium ions is suggested. Compounds decreasing the amount of extracellular ROS generation, yet affecting but minimally intracellular ROS generation, are promising for further investigation in vivo.

Effects of Resveratrol Supplementation on Oxidative Damage and Lipid Peroxidation Induced by Strenuous Exercise in Rats

The purpose of the present study was to investigate the effects of resveratrol supplementation on oxidative damage and lipid peroxidation induced by strenuous exercise in rats. The rats were randomly divided into five groups: a sedentary control group, an exercise control group, and three treatment exercise groups administered increasing doses of resveratrol (25, 50, and 100 mg/kg body weight). Resveratrol was administered by oral gavage once daily for four weeks. At the end of the four-week period, the rats performed a strenuous exercise on the treadmill, and the levels of lactate dehydrogenase (LDH), creatine kinase (CK), malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were measured. The results showed that resveratrol supplementation had protective effects against strenuous exercise-induced oxidative damage and lipid peroxidation by lowering the levels of LDH, CK, MDA, 4-HNE, and 8-OHdG in the serum or muscle of rats. These beneficial effects are probably owing to the inherent antioxidant activities of resveratrol.

"Disease modifying nutricals" for multiple sclerosis

The association between vitamin D and multiple sclerosis has (re)-opened new interest in nutrition and natural compounds in the prevention and treatment of this neuroinflammatory disease. The dietary amount and type of fat, probiotics and biologicals, salmon proteoglycans, phytoestrogens and protease inhibitor of soy, sodium chloride and trace elements, and fat soluble vitamins including D, A and E were all considered as disease-modifying nutraceuticals. Studies in experimental autoimmune encephalomyelitis mice suggest that poly-unsaturated fatty acids and their 'inflammation-resolving' metabolites and the gut microflora may reduce auto-aggressive immune cells and reduce progression or risk of relapse, and infection with whipworm eggs may positively change the gut-brain communication. Encouraged by the recent interest in multiple sclerosis-nutrition nature's pharmacy has been searched for novel compounds with anti-inflammatory, immune-modifying and antioxidative properties, the most interesting being the scorpion toxins that inhibit specific potassium channels of T cells and antioxidative compounds including the green tea flavonoid epigallocatechin-3-gallate, curcumin and the mustard oil glycoside from e.g. broccoli and sulforaphane. They mostly also inhibit pro-inflammatory signaling through NF-κB or toll-like receptors and stabilize the blood brain barrier. Disease modifying functions may also complement analgesic and anti-spastic effects of cannabis, its constituents, and of 'endocannabinoid enhancing' drugs or nutricals like inhibitors of fatty acid amide hydrolase. Nutricals will not solve multiple sclerosis therapeutic challenges but possibly support pharmacological interventions or unearth novel structures.

Resveratrol ameliorates high glucose and high-fat/sucrose diet-induced vascular hyperpermeability involving Cav-1/eNOS regulation

Vascular endothelial hyperpermeability is one of the manifestations of endothelial dysfunction. Resveratrol (Res) is considered to be beneficial in protecting endothelial function. However, currently, the exact protective effect and involved mechanisms of Res on endothelial dysfunction-hyperpermeability have not been completely clarified. The aim of present study is to investigate the effects of Res on amelioration of endothelial hyperpermeability and the role of caveolin-1 (Cav-1)/endothelial nitric oxide synthase (eNOS) pathway. Adult male Wistar rats were treated with a normal or high-fat/sucrose diet (HFS) with or without Res for 13 weeks. HFS and in vitro treatment with high glucose increased hyperpermeability in rat aorta, heart, liver and kidney and cultured bovine aortic endothelial cells (BAECs), respectively, which was attenuated by Res treatment. Application of Res reversed the changes in eNOS and Cav-1 expressions in aorta and heart of rats fed HFS and in BAECs incubated with high glucose. Res stimulated the formation of NO inhibited by high glucose in BAECs. Beta-Cyclodextrin (β-CD), caveolae inhibitor, showed the better beneficial effect than Res alone to up-regulate eNOS phosphorylative levels, while NG-Nitro-77 L-arginine methyl ester (L-NAME), eNOS inhibitor, had no effect on Cav-1 expression. Our studies suggested that HFS and in vitro treatment with high glucose caused endothelial hyperpermeability, which were ameliorated by Res at least involving Cav-1/eNOS regulation.