Oxidative stress in the skin: Impact and related protection.

Insulin-degrading enzyme (IDE), a 110-kDa metalloendopeptidase, hydrolyzes several physiologically relevant peptides, including insulin and amyloid-beta (Abeta). Human IDE has 13 cysteines and is inhibited by hydrogen peroxide and S-nitrosoglutathione (GSNO), donors of reactive oxygen and nitrogen species, respectively. Here, we report that the oxidative burst of BV-2 microglial cells leads to oxidation or nitrosylation of secreted IDE, leading to the reduced activity. Hydrogen peroxide and GSNO treatment of IDE reduces the V(max) for Abeta degradation, increases IDE oligomerization, and decreases IDE thermostability. Additionally, this inhibitory response of IDE is substrate-dependent, biphasic for Abeta degradation but monophasic for a shorter bradykinin-mimetic substrate. Our mutational analysis of IDE and peptide mass fingerprinting of GSNO-treated IDE using Fourier transform-ion cyclotron resonance mass spectrometer reveal a surprising interplay of Cys-178 with Cys-110 and Cys-819 for catalytic activity and with Cys-789 and Cys-966 for oligomerization. Cys-110 is near the zinc-binding catalytic center and is normally buried. The oxidation and nitrosylation of Cys-819 allow Cys-110 to be oxidized or nitrosylated, leading to complete inactivation of IDE. Cys-789 is spatially adjacent to Cys-966, and their nitrosylation and oxidation together trigger the oligomerization and inhibition of IDE. Interestingly, the Cys-178 modification buffers the inhibition caused by Cys-819 modification and prevents the oxidation or nitrosylation of Cys-110. The Cys-178 modification can also prevent the oligomerization-mediated inhibition. Thus, IDE can be intricately regulated by reactive oxygen or nitrogen species. The structure of IDE reveals the molecular basis for the long distance interactions of these cysteines and how they regulate IDE function.

SynopsisA novel treatment serum formulated to target multiple pathways in the anti-ageing cascade was tested both in vitro and in clinical settings. In vitro testing was performed to assess the ability to stimulate key proteins and genes fundamental to the anti-ageing cascade. The antioxidant potential of the formulation was studied in a UV-irradiation clinical study. A 12-week, open-label, single-centre study was conducted to determine whether this uniquely formulated topical treatment serum could improve visible signs of facial photodamage. Clinical evaluations showed statistically significant reductions in fine wrinkles and coarse wrinkles and improvements in skin texture, tone and radiance starting at week 4 with continued improvements at weeks 8 and 12. Subject self-assessments confirmed that the beneficial effects of the treatment serum were readily observed by the users. The treatment serum was well tolerated with no treatment-related adverse events reported during the 12-week study. Use of this novel treatment serum produced significant improvements in the visible signs of facial photodamage.RésuméUn nouveau sérum de traitement conçu pour cibler de multiples voies dans la cascade anti-âge a été testé à la fois in vitro et dans les conditions cliniques. Les tests in vitro ont été réalisés afin d'évaluer la capacité de stimuler les protéines et les gènes clés fondamentales de la cascade anti-vieillissement. Le potentiel antioxydant de la formulation a été étudié dans une étude clinique utilisant le rayonnement UV. Une étude de douze semaines, en mode ouvert, monocentrique a été menée afin de déterminer si ce sérum spécialement formulé pour le traitement topique peut améliorer les signes visibles du photo-vieillissement du visage. Des évaluations cliniques ont montré une réduction statistiquement significative des rides et des ridules secondaires et l'amélioration de la texture de la peau, du tonus et d'éclat à partir de la semaine 4 avec des améliorations continues aux semaines 8 et 12. Les autoévaluations par les sujets ont confirmé que les effets bénéfiques du sérum de traitement étaient facilement observés par les utilisateurs. Le sérum de traitement a été bien toléré avec aucun événement indésirable rapporté au cours de l'étude de 12 semaines. L'utilisation de ce nouveau sérum de traitement produit des améliorations significatives dans les signes visibles du photovieillissement du visage.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are constitutively generated in biological systems as side-products of oxidation reactions. Due to their high chemical reactivity, many organisms have developed effective elimination and defence systems for ROS and RNS. Although ROS and RNS are harmful nuisances for cells, the amount of ROS and RNS depends on the oxidation states and redox status of cells, and these reactive species can be utilized as the signalling molecules for adaptive response to the oxidative stress and unusual redox balance. All organisms from bacterial to mammalian, therefore, have specific sensing systems for ROS and RNS to promote survival. In addition, ROS and RNS are intentionally generated by specific enzymes under cellular control, which can serve as effective chemical weapons against invading pathogens. Hosts fight pathogens by generating ROS and RNS as the chemical weapons, while pathogens defend the attack of ROS and RNS by sensing them and activating their defence system. Although all of the cell components are targets of ROS and RNS, the iron ions are highly susceptible to ROS and RNS. Consequently, these ions are widely used as the active centres for sensing ROS and RNS. Binding of ROS or RNS to nonhaem iron-based sensors initiates specific responses such as expression of genes encoding enzymes in elimination and defence systems for ROS and RNS. In this chapter, several nonhaem iron-based sensors showing unique sensing mechanisms are reviewed, focusing on their molecular structure and reaction mechanisms for sensing ROS and RNS, as well as the biological significance of these reactive species.

Elucidation of the redox pathways in severe coronavirus disease 2019 (COVID-19) might aid in the treatment and management of the disease. However, the roles of individual reactive oxygen species (ROS) and individual reactive nitrogen species (RNS) in COVID-19 severity have not been studied to date. The main objective of this research was to assess the levels of individual ROS and RNS in the sera of COVID-19 patients. The roles of individual ROS and RNS in COVID-19 severity and their usefulness as potential disease severity biomarkers were also clarified for the first time. The current case-control study enrolled 110 COVID-19-positive patients and 50 healthy controls of both genders. The serum levels of three individual RNS (nitric oxide (NO•), nitrogen dioxide (ONO-), and peroxynitrite (ONOO-)) and four ROS (superoxide anion (O2•-), hydroxyl radical (•OH), singlet oxygen (1O2), and hydrogen peroxide (H2O2)) were measured. All subjects underwent thorough clinical and routine laboratory evaluations. The main biochemical markers for disease severity were measured and correlated with the ROS and RNS levels, and they included tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), the neutrophil-to-lymphocyte ratio (NLR), and angiotensin-converting enzyme 2 (ACE2). The results indicated that the serum levels of individual ROS and RNS were significantly higher in COVID-19 patients than in healthy subjects. The correlations between the serum levels of ROS and RNS and the biochemical markers ranged from moderate to very strongly positive. Moreover, significantly elevated serum levels of ROS and RNS were observed in intensive care unit (ICU) patients compared with non-ICU patients. Thus, ROS and RNS concentrations in serum can be used as biomarkers to track the prognosis of COVID-19. This investigation demonstrated that oxidative and nitrative stress play a role in the etiology of COVID-19 and contribute to disease severity; thus, ROS and RNS are probable innovative targets in COVID-19 therapeutics.

Aerobic metabolism generates biologically challenging reactive oxygen species (ROS) by the endogenous autooxidation of components of the electron transport chain (ETC). Basal levels of oxidative stress can dramatically rise upon activation of the NADPH oxidase-dependent respiratory burst. To minimize ROS toxicity, prokaryotic and eukaryotic organisms express a battery of low-molecular-weight thiol scavengers, a legion of detoxifying catalases, peroxidases, and superoxide dismutases, as well as a variety of repair systems. We present herein blockage of bacterial respiration as a novel strategy that helps the intracellular pathogen Salmonella survive extreme oxidative stress conditions. A Salmonella strain bearing mutations in complex I NADH dehydrogenases is refractory to the early NADPH oxidase-dependent antimicrobial activity of IFNgamma-activated macrophages. The ability of NADH-rich, complex I-deficient Salmonella to survive oxidative stress is associated with resistance to peroxynitrite (ONOO(-)) and hydrogen peroxide (H(2)O(2)). Inhibition of respiration with nitric oxide (NO) also triggered a protective adaptive response against oxidative stress. Expression of the NDH-II dehydrogenase decreases NADH levels, thereby abrogating resistance of NO-adapted Salmonella to H(2)O(2). NADH antagonizes the hydroxyl radical (OH(.)) generated in classical Fenton chemistry or spontaneous decomposition of peroxynitrous acid (ONOOH), while fueling AhpCF alkylhydroperoxidase. Together, these findings identify the accumulation of NADH following the NO-mediated inhibition of Salmonella's ETC as a novel antioxidant strategy. NO-dependent respiratory arrest may help mitochondria and a plethora of organisms cope with oxidative stress engendered in situations as diverse as aerobic respiration, ischemia reperfusion, and inflammation.

Reactive oxygen and nitrogen species in patients with rheumatoid arthritis as potential biomarkers for disease activity and the role of antioxidants

Free radicals, such as superoxide, hydroxyl and nitric oxide, and other "reactive species", such as hydrogen peroxide, hypochlorous acid and peroxynitrite, are formed in vivo. Some of these molecules, e.g. superoxide and nitric oxide, can be physiologically useful, but they can also cause damage under certain circumstances. Excess production of reactive oxygen or nitrogen species (ROS, RNS), their production in inappropriate relative amounts (especially superoxide and NO) or deficiencies in antioxidant defences may result in pathological stress to cells and tissues. This oxidative stress can have multiple effects. It can induce defence systems, and render tissues more resistant to subsequent insult. If oxidative stress is excessive or if defence and repair responses are inadequate, cell injury can be caused by such mechanisms as oxidative damage to essential proteins, lipid peroxidation, DNA strand breakage and base modification, and rises in the concentration of intracellular "free" Ca(2+). Considerable evidence supports the view that oxidative damage involving both ROS and RNS is an important contributor to the development of atherosclerosis. Peroxynitrite (derived by reaction of superoxide with nitric oxide) and transition metal ions (perhaps released by injury to the vessel wall) may contribute to lipid peroxidation in atherosclerotic lesions.

The tubule pathology of septic acute kidney injury: a neglected area of research comes of age

Protein S-nitrosylation mediated by cellular nitric oxide (NO) plays a primary role in executing biological functions in cGMP-independent NO signaling. Although S-nitrosylation appears similar to Cys oxidation induced by reactive oxygen species, the molecular mechanism and biological consequence remain unclear. We investigated the structural process of S-nitrosylation of protein-tyrosine phosphatase 1B (PTP1B). We treated PTP1B with various NO donors, including S-nitrosothiol reagents and compound-releasing NO radicals, to produce site-specific Cys S-nitrosylation identified using advanced mass spectrometry (MS) techniques. Quantitative MS showed that the active site Cys-215 was the primary residue susceptible to S-nitrosylation. The crystal structure of NO donor-reacted PTP1B at 2.6 A resolution revealed that the S-NO state at Cys-215 had no discernible irreversibly oxidized forms, whereas other Cys residues remained in their free thiol states. We further demonstrated that S-nitrosylation of the Cys-215 residue protected PTP1B from subsequent H(2)O(2)-induced irreversible oxidation. Increasing the level of cellular NO by pretreating cells with an NO donor or by activating ectopically expressed NO synthase inhibited reactive oxygen species-induced irreversible oxidation of endogenous PTP1B. These findings suggest that S-nitrosylation might prevent PTPs from permanent inactivation caused by oxidative stress.

Reactive oxygen and nitrogen species in pulmonary hypertension

Over the past several decades, nanotechnology has contributed to the progress of biomedicine, biomarker discovery, and the development of highly sensitive electroanalytical / electrochemical biosensors for in vitro and in vivo monitoring, and quantification of oxidative and nitrosative stress markers like reactive oxygen species (ROS) and reactive nitrogen species (RNS). A major source of ROS and RNS is oxidative stress in cells, which can cause many human diseases, including cancer. Therefore, the detection of local concentrations of ROS (e. g. superoxide anion radical; O2•- ) and RNS (e. g. nitric oxide radical; NO• and its metabolites) released from biological systems is increasingly important and needs a sophisticated detection strategy to monitor ROS and RNS in vitro and in vivo. In this review, we discuss the nanomaterials-based ROS and RNS biosensors utilizing electrochemical techniques with emphasis on their biomedical applications.

Post-translational S-glutathionylation occurs through the reversible addition of a proximal donor of glutathione to thiolate anions of cysteines in target proteins, where the modification alters molecular mass, charge, and structure/function and/or prevents degradation from sulfhydryl overoxidation or proteolysis. Catalysis of both the forward (glutathione S-transferase P) and reverse (glutaredoxin) reactions creates a functional cycle that can also regulate certain protein functional clusters, including those involved in redox-dependent cell signaling events. For translational application, S-glutathionylated serum proteins may be useful as biomarkers in individuals (who may also have polymorphic expression of glutathione S-transferase P) exposed to agents that cause oxidative or nitrosative stress.

Compartmentalization of Reactive Oxygen Species and Nitric Oxide Production in Plant Cells - An Overview.- Established and Proposed Roles of Xanthine Oxidoreductase in Oxidative and Reductive Pathways in Plants.- The Roles of Plant Peroxidases in the Metabolism of Reactive Nitrogen Species and Other Nitrogenous Compounds.- Mitochondrial Signaling in Plants Under Hypoxia: Use of Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS).-Feedback Loop of Non-Coupled Respiration and Reactive Oxygen Species Production in Plant Mitochondria.- Antioxidative Systems and Stress Tolerance - Insight from Wild and Cultivated Tomato Species.- The Role of Reactive Oxygen Species Under Ammonium Nutrition.- Allelopathic Compounds as Oxidative Stress Agents: Yes or NO.- The Role of Reactive Oxygen and Nitrogen Species in Bioenergetics, Metabolism and Signaling During Seed Germination.- ROS Signalling in Plant Embryogenesis.- Nitrosative Door in Seed Dormancy Alleviation and Germination.- Dissecting Nitric Oxide Signaling in Nucleus: Role of S-Nitrosylation in Regulating Nuclear Proteins.- Nitration and S-Nitrosylation: Two Post-Translational Modifications (Ptms) Mediated by Reactive Nitrogen Species (RNS) and Their Role in Signalling Processes of Plant Cells.- S-Nitrosoglutathione Reductase: A Key Regulator of S-Nitrosylation in Plant Development and Stress Responses.- Interaction of Calcium Signaling With Reactive Oxygen and Reactive Nitrogen Species.

Reactive oxygen species are reactive, partially reduced derivatives of molecular oxygen (O 2 ). Important reactive oxygen species in biologic systems include superoxide radical anion, hydrogen peroxide, and hydroxyl radical. Closely related species include the hypohalous acids, particularly hypochlorous acid; chloramine and substituted chloramines; and singlet oxygen. Reactive nitrogen species are derived from the simple diatomic gas, nitric oxide. Peroxynitrite and its protonated form, peroxynitrous acid, are the most significant reactive nitrogen species in biologic systems. A variety of enzymatic and nonenzymatic processes can generate reactive oxygen species and reactive nitrogen species in mammalian cells. An extensive body of experimental evidence from studies using animal models supports the view that reactive oxygen species and reactive nitrogen species are important in the pathogenesis of acute respiratory distress syndrome. This view is further supported by data from clinical studies that correlate biochemical evidence of reactive oxygen species-mediated or reactive nitrogen species-mediated stress with the development of acute respiratory distress syndrome. Despite these data, pharmacologic strategies directed at minimizing reactive oxygen species-mediated or reactive nitrogen species-mediated damage have yet to be successfully introduced into clinical practice. The most extensively studied compound in this regard is N -acetylcysteine; unfortunately, clinical trials with this compound in patients with acute respiratory distress syndrome have yielded disappointing results.

Chapter 18 - Mechanisms through Which Reactive Nitrogen and Oxygen Species Interact with Physiological Signaling Systems