In vivo ROS production and use of oxidative stress-derived biomarkers to detect the onset of diseases such as Alzheimer’s disease,Parkinson’s disease,and diabetes

Breakthroughs in biochemistry have furthered our understanding of the onset and progression of various diseases, and have advanced the development of new therapeutics. Oxidative stress and reactive oxygen species (ROS) are ubiquitous in biological systems. ROS can be formed non-enzymatically by chemical, photochemical and electron transfer reactions, or as the byproducts of endogenous enzymatic reactions, phagocytosis, and inflammation. Imbalances in ROS homeostasis, caused by impairments in antioxidant enzymes or non-enzymatic antioxidant networks, increase oxidative stress, leading to the deleterious oxidation and chemical modification of biomacromolecules such as lipids, DNA, and proteins. While many ROS are intracellular signaling messengers and most products of oxidative metabolisms are beneficial for normal cellular function, the elevation of ROS levels by light, hyperglycemia, peroxisomes, and certain enzymes causes oxidative stress-sensitive signaling, toxicity, oncogenesis, neurodegenerative diseases, and diabetes. Although the underlying mechanisms of these diseases are manifold, oxidative stress caused by ROS is a major contributing factor in their onset. This review summarizes the relationship between ROS and oxidative stress, with special reference to recent advancements in the detection of biomarkers related to oxidative stress. Further, we will introduce biomarkers for the early detection of neurodegenerative diseases and diabetes, with a focus on our recent work.     

The transition metals copper and iron in neurodegenerative diseases

Neurodegenerative diseases constitute a worldwide health problem. Metals like iron and copper are essential for life, but they are also involved in several neurodegenerative mechanisms such as protein aggregation, free radical generation and oxidative stress. The role of Fe and Cu, their pathogenic mechanisms and possible therapeutic relevance are discussed regarding four of the most common neurodegenerative diseases, Alzheimer's, Parkinson's and Huntington's diseases as well as amyotrophic lateral sclerosis. Metal-mediated oxidation by Fenton chemistry is a common feature for all those disorders and takes part of a self-amplifying damaging mechanism, leading to neurodegeneration. The interaction between metals and proteins in the nervous system seems to be a crucial factor for the development or absence of neurodegeneration. The present review also deals with the therapeutic strategies tested, mainly using metal chelating drugs. Metal accumulation within the nervous system observed in those diseases could be the result of compensatory mechanisms to improve metal availability for physiological processes.     

The role of NADPH oxidase (NOX) enzymes in neurodegenerative disease

Recently, mounting evidence implicating reactive oxygen species (ROS) generated by NADPH oxidase (NOX) enzymes in the pathogenesis of several neurodegenerative diseases including Amyotrophic lateral sclerosis (ALS), Alzheimer’s (AD), Parkinson’s (PD) and polyglutamine disease, have arisen. NOX enzymes are transmembrane proteins and generate reactive oxygen species by transporting electrons across lipid membranes. Under normal healthy conditions, low levels of ROS produced by NOX enzymes have been shown to play a role in neuronal differentiation and synaptic plasticity. However, in chronic neurodegenerative diseases over-activation of NOX in neurons, as well as in astrocytes and microglia, has been linked to pathogenic processes such as oxidative stress, exitotoxicity and neuroinflammation. In this review, we summarize the current knowledge about NOX functions in the healthy central nervous system and especially the role of NOX enzymes in neurodegenerative disease processes.     

RNA oxidation: A contributing factor or an epiphenomenon in the process of neurodegeneration

In the past decade, RNA oxidation has caught the attention of many researchers, working to uncover its role in the pathogenesis of neurodegenerative diseases. It has been well documented that RNA oxidation is involved in a wide variety of neurological diseases and is an early event in the process of neurodegeneration. The analysis of oxidized RNA species revealed that at least messenger RNA (mRNA) and ribosomal RNA (rRNA) are damaged in several neurodegenerative diseases, including Alzheimer's disease and amyotrophic lateral sclerosis (ALS). The magnitude of the RNA oxidation, at least in mRNA, is significantly high at the early stage of the disease. Oxidative damage to mRNA is not random but selective and many oxidized mRNAs are related to the pathogenesis of the disease. Several studies have suggested that oxidative modification of RNA affects the translational process and consequently produces less protein and/or defective protein. Furthermore, several proteins have been identified to be involved in handling of damaged RNA. Although a growing body of studies suggests that oxidative damage to RNA may be associated with neuron deterioration, further investigation and solid evidence are needed. In addition, further uncovering of the consequences and cellular handling of the oxidatively damaged RNA should be important focuses in this area and may provide significant insights into the pathogenesis of neurodegenerative diseases.     

Oxidative stress and neurodegeneration: the involvement of iron

Many evidences indicate that oxidative stress plays a significant role in a variety of human disease states, including neurodegenerative diseases. Iron is an essential metal for almost all living organisms due to its involvement in a large number of iron-containing proteins and enzymes, though it could be also toxic. Actually, free iron excess generates oxidative stress, particularly in brain, where anti-oxidative defences are relatively low. Its accumulation in specific regions is associated with pathogenesis in a variety of neurodegenerative diseases (i.e., Parkinson’s disease, Alzheimer’s disease, Huntington’s chorea, Amyotrophic Lateral Sclerosis and Neurodegeneration with Brain Iron Accumulation). Anyway, the extent of toxicity is dictated, in part, by the localization of the iron complex within the cell (cytosolic, lysosomal and mitochondrial), its biochemical form, i.e., ferritin or hemosiderin, as well as the ability of the cell to prevent the generation and propagation of free radical by the wide range of antioxidants and cytoprotective enzymes in the cell. Particularly, ferrous iron can act as a catalyst in the Fenton reaction that potentiates oxygen toxicity by generating a wide range of free radical species, including hydroxyl radicals (·OH). The observation that patients with neurodegenerative diseases show a dramatic increase in their brain iron content, correlated with the production of reactive oxigen species in these areas of the brain, conceivably suggests that disturbances in brain iron homeostasis may contribute to the pathogenesis of these disorders. The aim of this review is to describe the chemical features of iron in human beings and iron induced toxicity in neurodegenerative diseases. Furthermore, the attention is focused on metal chelating drugs therapeutic strategies.     

Water-soluble fractions from defatted sesame seeds protect human neuroblast cells against peroxyl radicals and hydrogen peroxide-induced oxidative stress

Oxidative stress is involved in the development of aging-related diseases, such as neurodegenerative diseases. Dietary antioxidants that can protect neuronal cells from oxidative damage play an important role in preventing such diseases. Previously, we reported that water-soluble fractions purified from defatted sesame seed flour exhibit good antioxidant activity in vitro. In the present study, we investigated the protective effects of white and gold sesame seed water-soluble fractions (WS-wsf and GS-wsf, respectively) against 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) and hydrogen peroxide (H₂O₂) induced oxidative stress in human neuroblast SH-SY5Y cells. Pretreatment with WS-wsf and GS-wsf did not protect cells against AAPH-induced cytotoxicity, while simultaneous co-treatment with AAPH significantly improved cell viability and inhibited membrane lipid peroxidation. These results suggest that WS-wsf and GS-wsf protect cells from AAPH-induced extracellular oxidative damage via direct scavenging of peroxyl radicals. When oxidative stress was induced by H₂O₂, pretreatment WS-wsf and GS-wsf significantly enhanced cell viability. These results suggest that in addition to radical scavenging, WS-wsf and GS-wsf enhance cellular resistance to intracellular oxidative stress by activation of the Nrf-2/ARE pathway as confirmed by the increased Nrf2 protein level in the nucleus and increased heme oxygenase 1 (HO-1) mRNA expression. The roles of ferulic and vanillic acids as bioactive antioxidants in these fractions were also confirmed. In conclusion, our results indicated that WS-wsf and GS-wsf, which showed antioxidant activity in vitro, are also efficient antioxidants in a cell system protecting SH-SY5Y cells against both extracellular and intracellular oxidative stress.     

Dual cell protective mechanisms activated by differing levels of oxidative stress in HT22 murine hippocampal cells

Oxidative stress is recognized as one of the pathogenic mechanisms involved in neurodegenerative disease. However, recent evidence has suggested that regulation of cellular fate in response to oxidative stress appears to be dependent on the stress levels. In this study, using HT22 cells, we attempted to understand how an alteration in the oxidative stress levels would influence neuronal cell fate. HT22 cell viability was reduced with exposure to high levels of oxidative stress, whereas, low levels of oxidative stress promoted cell survival. Erk1/2 activation induced by a low level of oxidative stress played a role in this cell protective effect. Intriguingly, subtoxic level of H₂O₂ induced expression of a growth factor, progranulin (PGRN), and exogenous PGRN pretreatment attenuated HT22 cell death induced by high concentrations of H₂O₂ in Erk1/2-dependent manner. Together, our study indicates that two different cell protection mechanisms are activated by differing levels of oxidative stress in HT22 cells.     

氧化应激及天然抗氧化剂对阿尔茨海默病的缓解作用（英文）

衰老是阿尔茨海默病（Alzheimer’s disease,AD）等神经退行性疾病的主要危险因素。氧化应激和自由基具有重要的生物学功能,氧化还原失衡导致氧化应激,与包括AD在内的许多人类疾病的病理生理有关。本文综述了活性氧（ROS）参与神经退行性疾病发病的相关机制,特别是氧化应激与AD其他关键机制的相互作用,并总结了茶多酚、L-茶氨酸、虾青素、EGb761、大豆异黄酮和烟碱在细胞和动物模型中对AD的防护作用以及在临床上对相关疾病的缓解作用。希望该综述能为AD的预防和治疗策略提供一些见解。     

Melatonin oxidative stress and neurodegenerative diseases

Oxidative Stress is implicated as one of the primary factors that contribute to the development of neurodegenerative diseases like Alzheimer's Disease, Parkinsonism and neurological conditions like epileptic seizures, stroke, brain damage, neurotrauma etc. The increased formation and release of oxygen free radicals coupled with the rather low antioxidative potential of the central nervous system are the major reasons that account for the enhanced oxidative stress seen in neuronal cells. In addition to this, brain is also enriched with polyunsaturated fatty acids that render neuronal cells easily vulnerable to oxidative attack. The fact that there is increased incidence of neurodegenerative disorders in aged individuals, has prompted many investigators to search for a common factor whose progressive decline with increase in age could account for increased oxidative stress resulting in senescence and age associated degenerative diseases. Since melatonin, the hormone secreted from the pineal gland has a remarkable anti-oxidant property and whose rate of production declines with increase in age, has prompted many to suggest that this hormone plays a crucial role in the genesis of neurodegenerative diseases. Melatonin cannot only scavenges oxygen free radicals like super oxide radical (O2-), hydroxyl radical (*OH), peroxyl radical (LOO*) and peroxynitrite anion (ONOO-), but can also enhance the antioxidative potential of the cell by stimulating the synthesis of antioxidative enzymes like super oxide dismutase (SOD), glutathione peroxidase (GPX), and also the enzymes that are involved in the synthesis of glutathione. In many instances, melatonin increases the expression of m RNA's of the antioxidative enzymes. Melatonin administration has been shown to be effective in counteracting the neurodegenerative conditions both in experimental models of neurodegenerative diseases and in patients suffering from such diseases. A disturbance of melatonin rhythm and secretion also has been noted in patients suffering from certain neurodegenerative diseases. From all these, it is evident that melatonin has a neuroprotective role.     

Retinol (Vitamin A) Increases α-Synuclein, β-Amyloid Peptide,Tau Phosphorylation and RAGE Content in Human SH-SY5Y Neuronal Cell Line

Retinoids (vitamin A and derivatives) are recognized as essential factors for central nervous system (CNS) development. Retinol (vitamin A) also was postulated to be a major antioxidant component of diet as it modulates reactive species (RS) production and oxidative stress in biological systems. Oxidative stress plays a major role either in pathogenesis or development of neurodegenerative diseases, or even in both. Here we investigate the role of retinol supplementation to human neuron-derived SH-SY5Y cells over RS production and biochemical markers associated to neurodegenerative diseases expressed at neuronal level in Parkinson’s disease and Alzheimer’s disease: α-synuclein, β-amyloid peptide, tau phosphorylation and RAGE. Retinol treatment (24 h) impaired cell viability and increased intracellular RS production at the highest concentrations (7 up to 20 µM). Antioxidant co-treatment (Trolox 100 µM) rescued cell viability and inhibited RS production. Furthermore, retinol (10 µM) increased the levels of α-synuclein, tau phosphorylation at Ser396, β-amyloid peptide and RAGE. Co-treatment with antioxidant Trolox inhibited the increased in RAGE, but not the effect of retinol on α-synuclein, tau phosphorylation and β-amyloid peptide accumulation. These data indicate that increased availability of retinol to neurons at levels above the cellular physiological concentrations may induce deleterious effects through diverse mechanisms, which include oxidative stress but also include RS-independent modulation of proteins associated to progression of neuronal cell death during the course of neurodegenerative diseases.     

Oxidative-stress-dependent up-regulation of Bcl-2 expression in the central nervous system of aged Fisher-344 rats

Oxidative stress has been shown to play a role in aging and in neurodegenerative disorders. Some of the consequences of oxidative stress are DNA base modifications, lipid peroxidation, and protein modifications such as formation of carbonyls and nitrotyrosine. These events may play a role in apoptosis, another factor in aging and neurodegeneration, in response to uncompensated oxidative stress. Bcl-2 is a mitochondrial protein that protects neurons from apoptotic stimuli including oxidative stress. Using immunohistochemistry and western blot analysis, here we show that Bcl-2 is up-regulated in the hippocampus and cerebellum of aged (24 months) Fisher 344 rats. Treatment with the free radical spin trap N-tert-butyl-alpha-phenylnitrone (PBN) effectively reverses this age-dependent Bcl-2 up-regulation indicating that this response is redox sensitive. This conclusion was further supported by inducing the same regional Bcl-2 up-regulation in young (3 months) Fisher 344 rats exposed to 100% normobaric O(2) for 48 h. Our results indicate that Bcl-2 expression is increased in the aged brain, possibly as a consequence of oxidative stress challenges. These results also illustrate the effectiveness of antioxidants in reversing age-related changes in the CNS and support further research to investigate their use in aging and in age-related neurodegenerative disorders.     

氧化应激相关性疾病中线粒体机制的研究进展

氧化应激是由体内生成的活性氧（reactive oxygen species,ROS）／活性氮（reactivenitro．genspecies,RNS）与抗氧化防御机制之间的平衡被打破引起的,这与许多疾病的发病机理相关,包括神经退行性病变、肿瘤、炎症性疾病等。而线粒体作为细胞代谢的中枢,是其作用的主要靶细胞器,氧化应激引起线粒体内脂质、蛋白质与核酸的损伤,导致线粒体结构和功能的改变,该文就线粒体在上述与氧化应激相关的疾病中改变的研究进展作一综述。     

Idebenone Ameliorates Rotenone-Induced Parkinson’s Disease in Rats Through Decreasing Lipid Peroxidation

Neurochemical Research - Oxidative stress is considered one of the mechanisms responsible for neurodegenerative diseases, especially for Parkinson’s disease. Since oxidative stress causes...     

Protective effect of daidzein against streptozotocin‐induced Alzheimer's disease via improving cognitive dysfunction and oxidative stress in rat model

Oxidative stress is performing an essential role in developing Alzheimer's disease (AD), and age‐related disorder and other neurodegenerative diseases. In existing research, we have aimed at investigating the daidzein (4′,7‐dihydroxyisoflavone) effect (10 and 20 mg/kg of body weight), as a free radical scavenger and antioxidant in streptozotocin (STZ) infused AD in rat model. Daidzein treatment led to significant improvement in intracerebroventricular‐streptozotocin (ICV‐STZ)‐induced memory and learning impairments that was evaluated by Morris water maze test and spontaneous locomotor activity. It significantly restored the alterations in malondialdehyde, catalase, superoxide dismutase, and reduced glutathione levels. In addition, histopathological observations in cerebral cortex and hippocampal areas confirmed the neuroprotective effect of daidzein. These outcomes provide experimental proof showing preventive effect of daidzein on memory, learning dysfunction and oxidative stress in case of ICV‐STZ rats. In conclusion, daidzein offers a potential treatment module for various neurodegenerative disorders with regard to mental deficits like AD.     

Oxidative Stress Induces Dephosphorylation of τ in Rat Brain Primary Neuronal Cultures

Abstract: Oxidative stress and free radical damage have been implicated in the neurodegenerative changes characteristic of several neurodegenerative diseases, including Alzheimer's disease. There is experimental evidence that the neurotoxicity of β-amyloid is mediated via free radicals, and as the deposition of β-amyloid apparently precedes the formation of paired helical filaments (PHF) in Alzheimer's disease, we have investigated whether subjecting primary neuronal cultures to oxidative stress induces changes in the phosphorylation state of the principal PHF protein τ that resemble those found in PHF-τ. Contrary to causing an increase in τ phosphorylation, treatment of neurones with hydrogen peroxide caused a dephosphorylation of τ and so we conclude that oxidative stress is not the direct cause of τ hyperphosphorylation and hence of PHF formation.     

Development and application of oxidative stress biomarkers

Abstract

Oxidative stress may cause a wide variety of free radical reactions to produce deleterious modifications in membranes, proteins, enzymes, and DNA. Reactive Oxygen Species (ROS) generated by myeloperoxidase (MPO) can induce lipid peroxidation and also play an important role in the generation of reactive chlorinating and brominating species. As the universal biomarkers, chemical, and immunochemical approach on oxidatively modified and halogenated tyrosines has been carried out. As amido-type adduct biomarkers, chemical, and immunochemical evaluation of hexanoyl- and propanoyl-lysines, hexanoyl- and propanoyl-dopamines and phospholipids were prepared and developed for application of evaluation of novel antioxidative functional food factors. We have also involved in application of oxidatively modified DNAs such as 8-hydroxy- and 8-halogenated deoxyguanosines as the useful biomarkers for age-related diseases using both in vitro and in vivo systems. Application of these oxidative stress biomarkers for novel type of functional food development and recent approach for development of novel evaluation systems are also discussed.     

Fatty acid oxidation and isoprostanes: Oxidative strain and oxidative stress

Oxidative stress is implicated as one of the key causes underlying many diseases. Free radicals are important constituents of basal physiology. Assessment of free radicals or the end products of their action has proved to be difficult. Consequently, authentication of the contribution of free radicals to physiology and pathology has usually been equivocal. Isoprostanes are biosynthesized in vivo, predominantly through free radical attack on arachidonic acid and are now regarded as robust biomarkers of oxidative stress in vivo. Isoprostanes are associated with many human diseases, and their concentration is altered over the course of normal human pregnancy, but their (patho)physiological roles have not yet been clearly defined. Measurement of F₂-isoprostanes in body fluids could offer a unique analytical opportunity to study the role of free radicals in physiology and pathophysiology in order to comprehend both oxidative strain and oxidative stress.     

Oxidative stress in patients with cardiovascular disease and chronic renal failure

Abstract

Oxidative response regulates many physiological response in human health, but if not properly regulated it could also lead to a number of deleterious effects. The importance of oxidative stress injury depends on the molecular target, the severity of the stress, and the mechanism by which the oxidative stress is imposed: it has been implicated in several diseases including cancer, neurodegenerative diseases, malaria, rheumatoid arthritis and cardiovascular and kidney disease. Most of the common diseases, such as hypertension, atherosclerosis, heart failure, and renal dysfunction, are associated with vascular functional and structural alterations including endothelial dysfunction, altered contractility, and vascular remodeling. Common to these processes is increased bioavailability of reactive oxygen species (ROS), decreased nitric oxide (NO) levels, and reduced antioxidant capacity. Oxidative processes are up-regulated also in patients with chronic renal failure (CRF) and seem to be a cause of elevated risk of morbidity and mortality in these patients.

In this review, we highlight the role of oxidative stress in cardiovascular and renal disease.