The Fumarate Reductase ofBacteroides thetaiotaomicron, unlike That ofEscherichia coli, Is Configured so that It Does Not Generate Reactive Oxygen Species

ABSTRACTThe impact of oxidative stress upon organismal fitness is most apparent in the phenomenon of obligate anaerobiosis. The root cause may be multifaceted, but the intracellular generation of reactive oxygen species (ROS) likely plays a key role. ROS are formed when redox enzymes accidentally transfer electrons to oxygen rather than to their physiological substrates. In this study, we confirm that the predominant intestinal anaerobeBacteroides thetaiotaomicrongenerates intracellular ROS at a very high rate when it is aerated. Fumarate reductase (Frd) is a prominent enzyme in the anaerobic metabolism of many bacteria, includingB. thetaiotaomicron, and prior studies ofEscherichia coliFrd showed that the enzyme is unusually prone to ROS generation. Surprisingly, in this study biochemical analysis demonstrated that theB. thetaiotaomicronFrd does not react with oxygen at all: neither superoxide nor hydrogen peroxide is formed. Subunit-swapping experiments indicated that this difference does not derive from the flavoprotein subunit at which ROS normally arise. Experiments with the related enzyme succinate dehydrogenase discouraged the hypothesis that heme moieties are responsible. Thus, resistance to oxidation may reflect a shift of electron density away from the flavin moiety toward the iron-sulfur clusters. This study shows that the autoxidizability of a redox enzyme can be suppressed by subtle modifications that do not compromise its physiological function. One implication is that selective pressures might enhance the oxygen tolerance of an organism by manipulating the electronic properties of its redox enzymes so they do not generate ROS.IMPORTANCEWhether in sediments or pathogenic biofilms, the structures of microbial communities are configured around the sensitivities of their members to oxygen. Oxygen triggers the intracellular formation of reactive oxygen species (ROS), and the sensitivity of a microbe to oxygen likely depends upon the rates at which ROS are formed inside it. This study supports that idea, as an obligate anaerobe was confirmed to generate ROS very rapidly upon aeration. However, the suspected source of the ROS was disproven, as the fumarate reductase of the anaerobe did not display the high oxidation rate of itsE. colihomologue. Evidently, adjustments in its electronic structure can suppress the tendency of an enzyme to generate ROS. Importantly, this outcome suggests that evolutionary pressure may succeed in modifying redox enzymes and thereby diminishing the stress that an organism experiences in oxic environments. The actual source of ROS in the anaerobe remains to be discovered.

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The Neuro-Protective Effects of the TSPO Ligands CB86 and CB204 on 6-OHDA-Induced PC12 Cell Death as an In Vitro Model for Parkinson’s Disease

Biology ◽

10.3390/biology10111183 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1183

Author(s):

Sheelu Monga ◽

Nunzio Denora ◽

Valentino Laquintana ◽

Rami Yashaev ◽

Abraham Weizman ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Parkinson’S Disease ◽

Parkinson's Disease ◽

Cell Death ◽

Neurodegenerative Disorder ◽

Reactive Oxygen ◽

Ros Generation ◽

Oxygen Species ◽

The Impact

Parkinson’s disease (PD) is a progressive neurodegenerative disorder which is characterized by the degeneration of dopaminergic neurons in substantia nigra (SN). Oxidative stress or reactive oxygen species (ROS) generation was suggested to play a role in this specific type of neurodegeneration. Therapeutic options which can target and counteract ROS generation may be of benefit. TSPO ligands are known to counteract with neuro-inflammation, ROS generation, apoptosis, and necrosis. In the current study, we investigated an in vitro cellular PD model by the assessment of 6-hydroxydopamine (6-OHDA, 80 µM)-induced PC12 neurotoxicity. Simultaneously to the exposure of the cells to 6-OHDA, we added the TSPO ligands CB86 and CB204 (25 µM each) and assessed the impact on several markers of cell death. The two ligands normalized significantly (57% and 52% respectively, from 44%; whereas the control was 68%) cell proliferation at different time points from 0–24 h. Additionally, we evaluated the effect of these two TSPO ligands on necrosis using propidium iodide (PI) staining and found that the ligands inhibited significantly the 6-OHDA-induced necrosis. As compared to control, the red count was increased up to 57-fold whereas CB86 and CB204 inhibited to 2.7-fold and 3.2-fold respectively. Necrosis was also analyzed by LDH assay which showed significant effect. Both assays demonstrated similar potent anti-necrotic effect of the two TSPO ligands. Reactive oxygen species (ROS) generation induced by 6-OHDA was also inhibited by the two TSPO ligand up to 1.3 and 1.5-fold respectively, as compared to 6-OHDA group. CB86 and CB204 inhibited also normalized the cell viability up to 1.8-fold after the exposure to 6-OHDA, as assessed by XTT assay. The two TSPO ligands also inhibited apoptosis significantly (1.3-fold for both) as assessed by apopxin green staining. In summary, it appears that the two TSPO ligands CB86 and CB204 can suppress cell death of PC12 induced by 6-OHDA. The results may be relevant to the use of these two TSPO ligands as therapeutic option neurodegenerative diseases like PD.

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Impact of CD14 on Reactive Oxygen Species Production from Human Leukocytes Primed byEscherichia coliLipopolysaccharides

Oxidative Medicine and Cellular Longevity ◽

10.1155/2019/6043245 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Dmitry S. Kabanov ◽

Olga Yu. Vwedenskaya ◽

Marina A. Fokina ◽

Elena M. Morozova ◽

Sergey V. Grachev ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Reactive Oxygen ◽

Polymorphonuclear Neutrophils ◽

Ros Generation ◽

Ros Production ◽

Oxygen Species ◽

Human Pmns ◽

Species Production ◽

The Impact ◽

Priming Activity

Lipopolysaccharides (LPS) from Gram-negative bacteria prime human polymorphonuclear neutrophils (PMNs) via multicomponent receptor cluster including CD14 and MD-2·TLR4 for the enhanced release of reactive oxygen species (ROS) were triggered by bacterial derived peptideN-formyl-methionyl-leucyl-phenylalanine (fMLP). In this study, we investigated the impact of CD14 on LPS-induced priming of human PMNs for fMLP-triggered ROS generation (respiratory or oxidative) burst. Monoclonal antibodies against human CD14 (mAbs) as well as isotype-matched IgG2a did not influence significantly fMLP-triggered ROS production from LPS-unprimed PMNs. Anti-CD14 mAbs (clone UCHM-1) attenuated LPS-induced priming of PMNs as it had been mirrored by fMLP-triggered decrease of ROS production. Similar priming activity of S-LPS or Re-LPS fromEscherichia colifor fMLP-triggered ROS release from PMNs was found. Obtained results suggest that glycosylphosphatidylinositol-anchored CD14 is the key player in LPS-induced PMN priming for fMLP-triggered ROS production. We believe that blockade of CD14 on the cell surface and clinical use of anti-CD14 mAbs or their Fab fragments may diminish the production of ROS and improve outcomes during cardiovascular diseases manifested by LPS-induced inflammation.

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The impact of reactive oxygen species in the development of cardiometabolic disorders: a review

Lipids in Health and Disease ◽

10.1186/s12944-021-01435-7 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Roland Akhigbe ◽

Ayodeji Ajayi

Keyword(s):

Oxidative Stress ◽

Reactive Oxygen Species ◽

Nicotinamide Adenine Dinucleotide Phosphate ◽

Reactive Oxygen ◽

Acid Oxidation ◽

Ros Generation ◽

Metabolic Memory ◽

Oxygen Species ◽

Cardiometabolic Disorders ◽

The Impact

AbstractOxidative stress, an alteration in the balance between reactive oxygen species (ROS) generation and antioxidant buffering capacity, has been implicated in the pathogenesis of cardiometabolic disorders (CMD). At physiological levels, ROS functions as signalling mediators, regulates various physiological functions such as the growth, proliferation, and migration endothelial cells (EC) and smooth muscle cells (SMC); formation and development of new blood vessels; EC and SMC regulated death; vascular tone; host defence; and genomic stability. However, at excessive levels, it causes a deviation in the redox state, mediates the development of CMD. Multiple mechanisms account for the rise in the production of free radicals in the heart. These include mitochondrial dysfunction and uncoupling, increased fatty acid oxidation, exaggerated activity of nicotinamide adenine dinucleotide phosphate oxidase (NOX), reduced antioxidant capacity, and cardiac metabolic memory. The purpose of this study is to discuss the link between oxidative stress and the aetiopathogenesis of CMD and highlight associated mechanisms. Oxidative stress plays a vital role in the development of obesity and dyslipidaemia, insulin resistance and diabetes, hypertension via various mechanisms associated with ROS-led inflammatory response and endothelial dysfunction.

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Cell respiration and formation of reactive oxygen species: facts and artefacts

Biochemical Society Transactions ◽

10.1042/bst0311308 ◽

2003 ◽

Vol 31 (6) ◽

pp. 1308-1311 ◽

Cited By ~ 84

Author(s):

H. Nohl ◽

A.V. Kozlov ◽

L. Gille ◽

K. Staniek

Keyword(s):

Reactive Oxygen Species ◽

Reactive Oxygen ◽

Single Electron ◽

High Rate ◽

Detection Methods ◽

Ros Generation ◽

Oxygen Species ◽

Single Electrons ◽

Major Argument

It is generally taken as an established fact that mitochondrial respiration is associated with the generation of small amounts of ROS (reactive oxygen species). There are many arguments supporting this side activity. A major argument is the particular physico-chemical configuration of dioxygen, which prevents the transfer of a pair of electrons. Instead, oxygen is reduced by the successive transfer of single electrons, necessarily leading to intermediates with odd electrons. The high rate of turnover of oxygen in the respiratory chain in combination with the existence of single-electron carriers supports the concept of mitochondria as the major cellular ROS generator. Experimental evidence on the ability of mitochondria to generate ROS was, however, based essentially on in vitro experiments with isolated mitochondria. A variety of structural and functional alterations associated with the removal of mitochondria from the cell, as well as the routinely applied ROS detection methods, may lead to artefactual deviation of odd electrons to dioxygen. We therefore checked these correlations in view of ROS formation, including the often reported effect of the membrane potential on the establishment of a redox couple with oxygen out of sequence. For this purpose we developed novel methods to prove the authenticity of mitochondria for ROS generation in the living cell. Based on our experiments, we can exclude spontaneous release of ROS from mitochondria. However, we describe conditions under which mitochondria can be transformed to mild ROS generators. The site of single-electron deviation to dioxygen was found to be ubiquinol interacting with the Rieske iron–sulphur protein and low-potential cytochrome b of the bc1 complex.

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The impact of the histidyl residue position on the formation and stability of Cu(ii) complexes and their ability of ROS generation

New Journal of Chemistry ◽

10.1039/d1nj00617g ◽

2021 ◽

Author(s):

Monika Katarzyna Lesiów ◽

Katarzyna Krupa

Keyword(s):

Reactive Oxygen Species ◽

Reactive Oxygen ◽

Ros Generation ◽

Oxygen Species ◽

The Impact ◽

Residue Position

Cu(ii) complexes with Ac-H1WKGPLR-NH, Ac-EH2KA-NH2, and Ac-KEH3K-NH2 peptides are able to generate reactive oxygen species.

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Increased cerebral mitochondrial dysfunction and reactive oxygen species with cardiopulmonary bypass

European Journal of Cardio-Thoracic Surgery ◽

10.1093/ejcts/ezaa439 ◽

2020 ◽

Author(s):

Lindsay E Volk ◽

Constantine D Mavroudis ◽

Tiffany Ko ◽

Thomas Hallowell ◽

Nile Delso ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Cardiopulmonary Bypass ◽

Mitochondrial Respiration ◽

Heart Defects ◽

Reactive Oxygen ◽

Neurological Injury ◽

Ros Generation ◽

Oxygen Species ◽

Experimental Animals ◽

The Impact

Abstract OBJECTIVES Neurodevelopmental injury after cardiac surgery using cardiopulmonary bypass (CPB) for congenital heart defects is common, but the mechanism behind this injury is unclear. This study examines the impact of CPB on cerebral mitochondrial reactive oxygen species (ROS) generation and mitochondrial bioenergetics. METHODS Twenty-three piglets (mean weight 4.2 ± 0.5 kg) were placed on CPB for either 1, 2, 3 or 4 h (n = 5 per group) or underwent anaesthesia without CPB (sham, n = 3). Microdialysis was used to measure metabolic markers of ischaemia. At the conclusion of CPB or 4 h of sham, brain tissue was harvested. Utilizing high-resolution respirometry, with simultaneous fluorometric analysis, mitochondrial respiration and ROS were measured. RESULTS There were no significant differences in markers of ischaemia between sham and experimental groups. Sham animals had significantly higher mitochondrial respiration than experimental animals, including maximal oxidative phosphorylation capacity of complex I (OXPHOSCI) (3.25 ± 0.18 vs 4-h CPB: 1.68 ± 0.10, P < 0.001) and maximal phosphorylating respiration capacity via convergent input through complexes I and II (OXPHOSCI+CII) (7.40 ± 0.24 vs 4-h CPB: 3.91 ± 0.20, P < 0.0001). At 4-h, experimental animals had significantly higher ROS related to non-phosphorylating respiration through complexes I and II (ETSCI+CII) than shams (1.08 ± 0.13 vs 0.64 ± 0.04, P = 0.026). CONCLUSIONS Even in the absence of local markers of ischaemia, CPB is associated with decreased mitochondrial respiration relative to shams irrespective of duration. Exposure to 4 h of CPB resulted in a significant increase in cerebral mitochondrial ROS formation compared to shorter durations. Further study is needed to improve the understanding of cerebral mitochondrial health and its effects on the pathophysiology of neurological injury following exposure to CPB.

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Reactive Oxygen Species in Host Plant Are Required for an Early Defense Response against Attack of Stagonospora nodorum Berk. Necrotrophic Effectors SnTox

Plants ◽

10.3390/plants10081586 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1586

Author(s):

Svetlana Veselova ◽

Tatyana Nuzhnaya ◽

Guzel Burkhanova ◽

Sergey Rumyantsev ◽

Igor Maksimov

Keyword(s):

Reactive Oxygen Species ◽

Early Stage ◽

Reactive Oxygen ◽

Triticum Aestivum L ◽

Redox Status ◽

Stagonospora Nodorum ◽

Ros Generation ◽

Ros Production ◽

Oxygen Species ◽

Necrotrophic Effectors

Reactive oxygen species (ROS) play a central role in plant immune responses. The most important virulence factors of the Stagonospora nodorum Berk. are multiple fungal necrotrophic effectors (NEs) (SnTox) that affect the redox-status and cause necrosis and/or chlorosis in wheat lines possessing dominant susceptibility genes (Snn). However, the effect of NEs on ROS generation at the early stages of infection has not been studied. We studied the early stage of infection of various wheat genotypes with S nodorum isolates -Sn4VD, SnB, and Sn9MN, carrying a different set of NE genes. Our results indicate that all three NEs of SnToxA, SnTox1, SnTox3 significantly contributed to cause disease, and the virulence of the isolates depended on their differential expression in plants (Triticum aestivum L.). The Tsn1–SnToxA, Snn1–SnTox1and Snn3–SnTox3 interactions played an important role in inhibition ROS production at the initial stage of infection. The Snn3–SnTox3 inhibited ROS production in wheat by affecting NADPH-oxidases, peroxidases, superoxide dismutase and catalase. The Tsn1–SnToxA inhibited ROS production in wheat by affecting peroxidases and catalase. The Snn1–SnTox1 inhibited the production of ROS in wheat by mainly affecting a peroxidase. Collectively, these results show that the inverse gene-for gene interactions between effector of pathogen and product of host sensitivity gene suppress the host’s own PAMP-triggered immunity pathway, resulting in NE-triggered susceptibility (NETS). These results are fundamentally changing our understanding of the development of this economical important wheat disease.

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CBIO-07. CELL DEATH INDUCED BY AN OSCILLATING MAGNETIC FIELD IN PATIENT DERIVED GLIOBLASTOMA CELLS IS MEDIATED BY REACTIVE OXYGEN SPECIES

Neuro-Oncology ◽

10.1093/neuonc/noaa215.067 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii17-ii17

Author(s):

Shashank Hambarde ◽

Martyn Sharpe ◽

David Baskin ◽

Santosh Helekar

Keyword(s):

Reactive Oxygen Species ◽

Cell Death ◽

Cell Viability ◽

Cortical Neurons ◽

Reactive Oxygen ◽

Great Promise ◽

Antioxidant Vitamin ◽

Ros Generation ◽

Oxygen Species ◽

Novel Therapy

Abstract Noninvasive cancer therapy with minimal side effects would be ideal for improving patient outcome in the clinic. We have developed a novel therapy using strong rotating magnets mounted on a helmet. They generate oscillating magnetic fields (OMF) that penetrate through the skull and cover the entire brain. We have demonstrated that OMF can effectively kill patient derived glioblastoma (GBM) cells in cell culture without having cytotoxic effects on cortical neurons and normal human astrocytes (NHA). Exposure of GBM cells to OMF reduced the cell viability by 33% in comparison to sham-treated cells (p< 0.001), while not affecting NHA cell viability. Time lapse video-microscopy for 16 h after OMF exposure showed a marked elevation of mitochondrial reactive oxygen species (ROS), and rapid apoptosis of GBM cells due to activation of caspase 3. Addition of a potent antioxidant vitamin E analog Trolox effectively blocked OMF-induced GBM cell death. Furthermore, OMF significantly potentiated the cytotoxic effect of the pro-oxidant Benzylamine. The results of our studies demonstrate that OMF-induced cell death is mediated by ROS generation. These results demonstrate a potent oncolytic effect on GBM cells that is novel and unrelated to any previously described therapy, including a very different mechanism of action and different technology compared to Optune therapy. The effect is very powerful, and unlike Optune, can be seen within hours after initiation of treatment. We believe that this technology holds great promise for new, effective and nontoxic treatment of glioblastoma.

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Assessment of Physico-Chemical and Toxicological Properties of Commercial 2D Boron Nitride Nanopowder and Nanoplatelets

International Journal of Molecular Sciences ◽

10.3390/ijms22020567 ◽

2021 ◽

Vol 22 (2) ◽

pp. 567

Author(s):

Brixhilda Domi ◽

Kapil Bhorkar ◽

Carlos Rumbo ◽

Labrini Sygellou ◽

Spyros N. Yannopoulos ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Boron Nitride ◽

A549 Cells ◽

Reactive Oxygen ◽

Slight Reduction ◽

Oxygen Species ◽

Potential Toxicity ◽

Cellular Models ◽

Physico Chemical ◽

The Impact

Boron nitride (BN) nanomaterials have been increasingly explored for potential applications in chemistry and biology fields (e.g., biomedical, pharmaceutical, and energy industries) due to their unique physico-chemical properties. However, their safe utilization requires a profound knowledge on their potential toxicological and environmental impact. To date, BN nanoparticles have been considered to have a high biocompatibility degree, but in some cases, contradictory results on their potential toxicity have been reported. Therefore, in the present study, we assessed two commercial 2D BN samples, namely BN-nanopowder (BN-PW) and BN-nanoplatelet (BN-PL), with the objective to identify whether distinct physico-chemical features may have an influence on the biological responses of exposed cellular models. Morphological, structural, and composition analyses showed that the most remarkable difference between both commercial samples was the diameter of their disk-like shape, which was of 200–300 nm for BN-PL and 100–150 nm for BN-PW. Their potential toxicity was investigated using adenocarcinomic human alveolar basal epithelial cells (A549 cells) and the unicellular fungus Saccharomycescerevisiae, as human and environmental eukaryotic models respectively, employing in vitro assays. In both cases, cellular viability assays and reactive oxygen species (ROS) determinations where performed. The impact of the selected nanomaterials in the viability of both unicellular models was very low, with only a slight reduction of S. cerevisiae colony forming units being observed after a long exposure period (24 h) to high concentrations (800 mg/L) of both nanomaterials. Similarly, BN-PW and BN-PL showed a low capacity to induce the formation of reactive oxygen species in the studied conditions. Even at the highest concentration and exposure times, no major cytotoxicity indicators were observed in human cells and yeast. The results obtained in the present study provide novel insights into the safety of 2D BN nanomaterials, indicating no significant differences in the toxicological potential of similar commercial products with a distinct lateral size, which showed to be safe products in the concentrations and exposure conditions tested.

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MitoQ Is Able to Modulate Apoptosis and Inflammation

International Journal of Molecular Sciences ◽

10.3390/ijms22094753 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4753

Author(s):

Elisa Piscianz ◽

Alessandra Tesser ◽

Erika Rimondi ◽

Elisabetta Melloni ◽

Claudio Celeghini ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Mevalonate Pathway ◽

Neuronal Cell ◽

Reactive Oxygen ◽

Mitochondrial Activity ◽

Oxygen Species ◽

Short Period ◽

Inflammatory Stimuli ◽

Apoptosis And Inflammation ◽

The Impact

Mitoquinone (MitoQ) is a mitochondrial reactive oxygen species scavenger that is characterized by high bioavailability. Prior studies have demonstrated its neuroprotective potential. Indeed, the release of reactive oxygen species due to damage to mitochondrial components plays a pivotal role in the pathogenesis of several neurodegenerative diseases. The present study aimed to examine the impact of the inflammation platform activation on the neuronal cell line (DAOY) treated with specific inflammatory stimuli and whether MitoQ addition can modulate these deregulations. DAOY cells were pre-treated with MitoQ and then stimulated by a blockade of the cholesterol pathway, also called mevalonate pathway, using a statin, mimicking cholesterol deregulation, a common parameter present in some neurodegenerative and autoinflammatory diseases. To verify the role played by MitoQ, we examined the expression of genes involved in the inflammation mechanism and the mitochondrial activity at different time points. In this experimental design, MitoQ showed a protective effect against the blockade of the mevalonate pathway in a short period (12 h) but did not persist for a long time (24 and 48 h). The results obtained highlight the anti-inflammatory properties of MitoQ and open the question about its application as an effective adjuvant for the treatment of the autoinflammatory disease characterized by a cholesterol deregulation pathway that involves mitochondrial homeostasis.

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