Analysis of DHE-derived oxidation products by HPLC in the assessment of superoxide production and NADPH oxidase activity in vascular systems

Cigarette Smoke-Induced Reactive Oxygen Species Formation: A Concise Review

Smoking is recognized as a significant risk factor for numerous disorders, including cardiovascular diseases, respiratory conditions, and various forms of cancer. While the exact pathogenic mechanisms continue to be explored, the induction of oxidative stress via the production of excess reactive oxygen species (ROS) is widely accepted as a primary molecular event that predisposes individuals to these smoking-related ailments. This review focused on how cigarette smoke (CS) promotes ROS formation rather than the pathophysiological repercussions of ROS and oxidative stress. A comprehensive analysis of existing studies revealed the following key ways through which CS imposes ROS burden on biological systems: (1) ROS, as well as radicals, are intrinsically present in CS, (2) CS constituents generate ROS through chemical reactions with biomolecules, (3) CS stimulates cellular ROS sources to enhance production, and (4) CS disrupts the antioxidant system, aggravating the ROS generation and its functions. While the evidence supporting these mechanisms is chiefly based on in vitro and animal studies, the direct clinical relevance remains to be fully elucidated. Nevertheless, this understanding is fundamental for deciphering molecular events leading to oxidative stress and for developing intervention strategies to counter CS-induced oxidative stress.

Bradykinin promotes murine melanoma cell migration and invasion through endogenous production of superoxide and nitric oxide

Spatial confinement and temporal regulation of signaling by nitric oxide (NO) and reactive oxygen species (ROS) occurs in cancer cells. Signaling mediated by NO and ROS was investigated in two sub clones of the murine melanoma B16F10-Nex2 cell line, Nex10C and Nex8H treated or not with bradykinin (BK). The sub clone Nex10C, similar to primary site cells, has a low capacity for colonizing the lungs, whereas the sub clone Nex8H, similar to metastatic cells, corresponds to a highly invasive melanoma. BK-treated Nex10C cells exhibited a transient increase in NO and an inhibition in basal O₂^- levels. Inhibition of endogenous NO production by l-NAME resulted in detectable levels of O₂^-. l-NAME promoted Rac1 activation and enhanced Rac1-PI3K association. l-NAME in the absence of BK resulted in Nex10C cell migration and invasion, suggesting that NO is a negative regulator of O₂^- mediated cell migration and cell invasion. BK-treated Nex8H cells sustained endogenous NO production through the activation of NOS3. NO activated Rac1 and promoted Rac1-PI3K association. NO stimulated cell migration and cell invasion through a signaling axis involving Ras, Rac1 and PI3K. In conclusion, a role for O₂^- and NO as positive regulators of Rac1-PI3K signaling associated with cell migration and cell invasion is proposed respectively for Nex10C and Nex8H murine melanoma cells.

Increased NOS coupling by the metabolite tetrahydrobiopterin (BH4) reduces preeclampsia/IUGR consequences

Preeclampsia (PE) is a high-prevalence pregnancy disease characterized by placental insufficiency, gestational hypertension, and proteinuria. Overexpression of the A isoform of the STOX1 transcription factor (STOX1A) recapitulates PE in mice, and STOX1A overexpressing trophoblasts recapitulate PE patients hallmarks in terms of gene expression and pathophysiology. STOX1 overexpression induces nitroso-redox imbalance and mitochondrial hyper-activation. Here, by a thorough analysis on cell models, we show that STOX1 overexpression in trophoblasts alters inducible nitric oxide synthase (iNOS), nitric oxide (NO) content, the nitroso-redox balance, the antioxidant defense, and mitochondrial function. This is accompanied by specific alterations of the Krebs cycle leading to reduced l-malate content. By increasing NOS coupling using the metabolite tetrahydrobiopterin (BH4) we restore this multi-step pathway in vitro. Moving in vivo on two different rodent models (STOX1 mice and RUPP rats, alike early onset and late onset preeclampsia, respectively), we show by transcriptomics that BH4 directly reverts STOX1-deregulated gene expression including glutathione metabolism, oxidative phosphorylation, cholesterol metabolism, inflammation, lipoprotein metabolism and platelet activation, successfully treating placental hypotrophy, gestational hypertension, proteinuria and heart hypertrophy. In the RUPP rats we show that the major fetal issue of preeclampsia, Intra Uterine Growth Restriction (IUGR), is efficiently corrected. Our work posits on solid bases BH4 as a novel potential therapy for preeclampsia.

Doxorubicin induces cardiotoxicity in a pluripotent stem cell model of aggressive B cell lymphoma cancer patients

Cancer therapies with anthracyclines have been shown to induce cardiovascular complications. The aims of this study were to establish an in vitro induced pluripotent stem cell model (iPSC) of anthracycline-induced cardiotoxicity (ACT) from patients with an aggressive form of B-cell lymphoma and to examine whether doxorubicin (DOX)-treated ACT-iPSC cardiomyocytes (CM) can recapitulate the clinical features exhibited by patients, and thus help uncover a DOX-dependent pathomechanism. ACT-iPSC CM generated from individuals with CD20⁺ B-cell lymphoma who had received high doses of DOX and suffered cardiac dysfunction were studied and compared to control-iPSC CM from cancer survivors without cardiac symptoms. In cellular studies, ACT-iPSC CM were persistently more susceptible to DOX toxicity including augmented disorganized myofilament structure, changed mitochondrial shape, and increased apoptotic events. Consistently, ACT-iPSC CM and cardiac fibroblasts isolated from fibrotic human ACT myocardium exhibited higher DOX-dependent reactive oxygen species. In functional studies, Ca²⁺ transient amplitude of ACT-iPSC CM was reduced compared to control cells, and diastolic sarcoplasmic reticulum Ca²⁺ leak was DOX-dependently increased. This could be explained by overactive CaMKIIδ in ACT CM. Together with DOX-dependent augmented proarrhythmic cellular triggers and prolonged action potentials in ACT CM, this suggests a cellular link to arrhythmogenic events and contractile dysfunction especially found in ACT engineered human myocardium. CamKIIδ inhibition prevented proarrhythmic triggers in ACT. In contrast, control CM upregulated SERCA2a expression in a DOX-dependent manner, possibly to avoid heart failure conditions. In conclusion, we developed the first human patient-specific stem cell model of DOX-induced cardiac dysfunction from patients with B-cell lymphoma. Our results suggest that DOX-induced stress resulted in arrhythmogenic events associated with contractile dysfunction and finally in heart failure after persistent stress activation in ACT patients.

The role of mitochondrial reactive oxygen species in insulin resistance

Insulin resistance is one of the earliest pathological features of a suite of diseases including type 2 diabetes collectively referred to as metabolic syndrome. There is a growing body of evidence from both pre-clinical studies and human cohorts indicating that reactive oxygen species, such as the superoxide radical anion and hydrogen peroxide are key players in the development of insulin resistance. Here we review the evidence linking mitochondrial reactive oxygen species generated within mitochondria with insulin resistance in adipose tissue and skeletal muscle, two major insulin sensitive tissues. We outline the relevant mitochondria-derived reactive species, how the mitochondrial redox state is regulated, and methodologies available to measure mitochondrial reactive oxygen species. Importantly, we highlight key experimental issues to be considered when studying the role of mitochondrial reactive oxygen species in insulin resistance. Evaluating the available literature on both mitochondrial reactive oxygen species/redox state and insulin resistance in a variety of biological systems, we conclude that the weight of evidence suggests a likely role for mitochondrial reactive oxygen species in the etiology of insulin resistance in adipose tissue and skeletal muscle. However, major limitations in the methods used to study reactive oxygen species in insulin resistance as well as the lack of data linking mitochondrial reactive oxygen species and cytosolic insulin signaling pathways are significant obstacles in proving the mechanistic link between these two processes. We provide a framework to guide future studies to provide stronger mechanistic information on the link between mitochondrial reactive oxygen species and insulin resistance as understanding the source, localization, nature, and quantity of mitochondrial reactive oxygen species, their targets and downstream signaling pathways may pave the way for important new therapeutic strategies.

Nitroxyl Radical as a Theranostic Contrast Agent in Magnetic Resonance Redox Imaging

Significance:In vivo assessment of paramagnetic and diamagnetic conversions of nitroxyl radicals based on cyclic redox mechanism can be an index of tissue redox status. The redox mechanism of nitroxyl radicals, which enables their use as a normal tissue-selective radioprotector, is seen as being attractive on planning radiation therapy. Recent Advances:In vivo redox imaging using nitroxyl radicals as redox-sensitive contrast agents has been developed to assess tissue redox status. Chemical and biological behaviors depending on chemical structures of nitroxyl radical compounds have been understood in detail. Polymer types of nitroxyl radical contrast agents and/or nitroxyl radical-labeled drugs were designed for approaching theranostics. Critical Issues: Nitroxyl radicals as magnetic resonance imaging (MRI) contrast agents have several advantages compared with those used in electron paramagnetic resonance (EPR) imaging, while support by EPR spectroscopy is important to understand information from MRI. Redox-sensitive paramagnetic contrast agents having a medicinal benefit, that is, nitroxyl-labeled drug, have been developed and proposed. Future Directions: A development of suitable nitroxyl contrast agent for translational theranostic applications with high reaction specificity and low normal tissue toxicity is under progress. Nitroxyl radicals as redox-sensitive magnetic resonance contrast agents can be a useful tool to detect an abnormal tissue redox status such as disordered oxidative stress. Antioxid. Redox Signal. 36, 95-121.

Detection of superoxide radical in all biological systems by Thin Layer Chromatography

The study presents a new method that detects O₂^•-, via quantification of 2-hydroxyethidium (2-ΟΗ-Ε⁺) as low as ∼30 fmoles by High-Performance Thin Layer Chromatography (HPTLC). The method isolates 2-ΟΗ-Ε⁺ after its extraction by the anionic detergent SDS (at 18-fold higher than its CMC) together with certain organic/inorganic reagents, and its HPTLC-separation from di-ethidium (di-Ε⁺) and ethidium (Ε⁺). Quantification of 2-OH-E⁺ is based on its ex/em maxima at 290/540 nm, and of di-E⁺ and E⁺ at 295/545 nm. The major innovations of the present method are the development of protocols for (i) efficient extraction (by SDS) and (ii) sensitive quantification (by HPTLC) for 2-OH-E⁺ (as well as di-E⁺ and E⁺) from most biological systems (animals, plants, cells, subcellular compartments, fluids). The method extracts 2-ΟΗ-Ε⁺ (by neutralizing the strong binding between its quaternary N⁺ and negatively charged sites on phospholipids, DNA etc) together with free HE, while protects both from biological oxidases, and also extracts/quantifies total proteins (hydrophilic and hydrophobic) for expressing O₂^•- levels per protein quantity. The method also uses SDS (at 80-fold lower than its CMC) to extract/remove/wash 2-ΟΗ-Ε⁺ from cell/organelle exterior membrane sites, for more accurate internal content quantification. The new method is applied on indicative biological systems: (1) artificially stressed (mouse organs and liver mitochondria and nuclei, ±exposed to paraquat, a known O₂^•- generator), and (2) physiologically stressed (cauliflower plant, exposed to light/dark).

Aedes aegypti Infection With Trypanosomatid Strigomonas culicis Alters Midgut Redox Metabolism and Reduces Mosquito Reproductive Fitness

Aedes aegypti mosquitoes transmit arboviruses of important global health impact, and their intestinal microbiota can influence vector competence by stimulating the innate immune system. Midgut epithelial cells also produce toxic reactive oxygen species (ROS) by dual oxidases (DUOXs) that are essential players in insect immunity. Strigomonas culicis is a monoxenous trypanosomatid that naturally inhabits mosquitoes; it hosts an endosymbiotic bacterium that completes essential biosynthetic pathways of the parasite and influences its oxidative metabolism. Our group previously showed that S. culicis hydrogen peroxide (H₂O₂)-resistant (WTR) strain is more infectious to A. aegypti mosquitoes than the wild-type (WT) strain. Here, we investigated the influence of both strains on the midgut oxidative environment and the effect of infection on mosquito fitness and immunity. WT stimulated the production of superoxide by mitochondrial metabolism of midgut epithelial cells after 4 days post-infection, while WTR exacerbated H₂O₂ production mediated by increased DUOX activity and impairment of antioxidant system. The infection with both strains also disrupted the fecundity and fertility of the females, with a greater impact on reproductive fitness of WTR-infected mosquitoes. The presence of these parasites induced specific transcriptional modulation of immune-related genes, such as attacin and defensin A during WTR infection (11.8- and 6.4-fold, respectively) and defensin C in WT infection (7.1-fold). Thus, we propose that A. aegypti oxidative response starts in early infection time and does not affect the survival of the H₂O₂-resistant strain, which has a more efficient antioxidant system. Our data provide new biological aspects of A. aegypti–S. culicis relationship that can be used later in alternative vector control strategies.

Metastatic Melanoma Progression Is Associated with Endothelial Nitric Oxide Synthase Uncoupling Induced by Loss of eNOS:BH4 Stoichiometry

Melanoma is the most aggressive type of skin cancer due to its high capability of developing metastasis and acquiring chemoresistance. Altered redox homeostasis induced by increased reactive oxygen species is associated with melanomagenesis through modulation of redox signaling pathways. Dysfunctional endothelial nitric oxide synthase (eNOS) produces superoxide anion (O2-•) and contributes to the establishment of a pro-oxidant environment in melanoma. Although decreased tetrahydrobiopterin (BH4) bioavailability is associated with eNOS uncoupling in endothelial and human melanoma cells, in the present work we show that eNOS uncoupling in metastatic melanoma cells expressing the genes from de novo biopterin synthesis pathway Gch1, Pts, and Spr, and high BH4 concentration and BH4:BH2 ratio. Western blot analysis showed increased expression of Nos3, altering the stoichiometry balance between eNOS and BH4, contributing to NOS uncoupling. Both treatment with L-sepiapterin and eNOS downregulation induced increased nitric oxide (NO) and decreased O2• levels, triggering NOS coupling and reducing cell growth and resistance to anoikis and dacarbazine chemotherapy. Moreover, restoration of eNOS activity impaired tumor growth in vivo. Finally, NOS3 expression was found to be increased in human metastatic melanoma samples compared with the primary site. eNOS dysfunction may be an important mechanism supporting metastatic melanoma growth and hence a potential target for therapy.

To Love and to Kill: Accurate and Selective Colorimetry for Both Chloride and Mercury Ions Regulated by Electro-Synthesized Oxidase-like SnTe Nanobelts

Herein, SnTe nanobelts (NBs) with efficient oxidase-mimetic activity were synthesized by the simple electrochemical exfoliation method. A specific inhibition effect of Cl^- on the enzymatic behavior of the pure SnTe NBs was discovered, which was accordingly used for establishing a highly feasible, sensitive, selective, and stable Cl^- colorimetric assay. The detection concentration range was 50 nM to 1 mM, and the lowest detection limit was 20 nM for Cl^-. In addition, a signal on-off-on route based on the SnTe NB nanozyme was designed to realize the reliable and specific detection of Hg²⁺. Therein, the SnTe NBs were grafted with gold nanoparticles to form a hybrid of SnTe/Au, resulting in the depression of the oxidase-like activity, which can then be recovered in the presence of the Hg²⁺ due to the formation of a gold amalgam. Especially, it was found that the high concentration of Cl^- over 3 mM could again exert suppression influence toward the enzymatic activity of the SnTe/Au-Hg system. Based on the to-love-and-to-kill interaction between Cl^- and Hg²⁺, the detection range for Cl^- can be extended to 40 to 250 mM. In return, the assays of Cl^- could avoid in advance its interference toward the accurate Hg²⁺ assays. We systematically clarified the oxidase-like catalytic mechanism of the SnTe-derived nanozyme systems. The as-proposed colorimetry can be successfully applied in practical samples including the sweat, human serum, or seawater/tap water, relating to cystic fibrosis, hyper-/hypochloremia, or environmental control, respectively.

Toll-like receptor 7-driven lupus autoimmunity induces hypertension and vascular alterations in mice

OBJECTIVE

To investigate whether toll-like receptor 7 (TLR7) activation induces an increase in blood pressure and vascular damage in wild-type mice treated with the TLR7 agonist imiquimod (IMQ).

METHODS

Female BALB/c mice (7-9 week old) were randomly assigned to two experimental groups: an untreated control group and a group treated topically with IMQ (IMQ-treated) for 4 or 8 weeks. A group of IMQ-treated mice that take a combination of the antioxidants tempol and apocynin, and another treated IL-17-neutralizing antibody were also performed.

RESULTS

TLR7 activation gradually increased blood pressure, associated with elevated plasma levels of anti-dsDNA autoantibodies, splenomegaly, hepatomegaly, and severe expansion of splenic immune cells with an imbalance between proinflammatory T cells and regulatory T cells. TLR7 activation induced a marked vascular remodeling in mesenteric arteries characterized by an increased media--lumen ratio (≈40%), and an impaired endothelium-dependent vasorelaxation in aortas from wild-type mice after 8 weeks of treatment. In addition, an increased ROS production, as a result of the upregulation of NADPH oxidase subunits, and an enhanced vascular inflammation were found in aortas from IMQ-treated mice. These functional and structural vascular alterations induced by IMQ were improved by antioxidant treatment. Anti-IL-17 treatment reduced blood pressure and improved endothelial dysfunction in IMQ-treated mice.

CONCLUSION

Our results demonstrate that TLR7 activation induces the development of hypertension and vascular damage in BALB/c mice, and further underscore the increased vascular inflammation and oxidative stress, mediated in part by IL-17, as key factors contributing to cardiovascular complications in this TLR7-driven lupus autoimmunity model.

Evaluation of the vital viability and their application in fungal spores' disinfection with flow cytometry

More attention was focused on fungi contamination in drinking water. Most researches about the inactivation of fungal spores has been conducted on disinfection efficiency and the leakage of intracellular substances. However, the specific structural damage of fungal spores treated by different disinfectants is poorly studied. In this study, the viability assessment methods of esterase activities and intracellular reactive oxygen species (ROS) were optimized, and the effects of chlorine-based disinfectants on fungal spores were evaluated by flow cytometry (FCM) and plating. The optimal staining conditions for esterase activity detection were as follows: fungal spores (10⁶ cells/mL) were stained with 10 μM carboxyfluorescein diacetate and 50 mM ethylene diamine tetraacetic acid at 33 °C for 10 min (in dark). The optimal staining conditions for intracellular ROS detection were as follows: dihydroethidium (the final concentration of 2 μg/mL) was added into fungal suspensions (10⁶ cells/mL), and then samples were incubated at 35 °C for 20 min (in dark). The cell culturability, membrane integrity, esterase activities, and intracellular ROS were examined to reveal the structural damage of fungal spores and underlying inactivation mechanisms. Disinfectants would cause the loss of the cell viability via five main steps: altered the morphology of fungal spores; increased the intracellular ROS levels; decreased the culturability, esterase activities and membrane integrity, thus leading to the irreversible death. It is appropriate to assess the effects of disinfectants on fungal spores and investigate their inactivation mechanisms using FCM.

Actin Cytoskeleton Regulation by the Yeast NADPH Oxidase Yno1p Impacts Processes Controlled by MAPK Pathways

Reactive oxygen species (ROS) that exceed the antioxidative capacity of the cell can be harmful and are termed oxidative stress. Increasing evidence suggests that ROS are not exclusively detrimental, but can fulfill important signaling functions. Recently, we have been able to demonstrate that a NADPH oxidase-like enzyme (termed Yno1p) exists in the single-celled organism Saccharomyces cerevisiae. This enzyme resides in the peripheral and perinuclear endoplasmic reticulum and functions in close proximity to the plasma membrane. Its product, hydrogen peroxide, which is also produced by the action of the superoxide dismutase, Sod1p, influences signaling of key regulatory proteins Ras2p and Yck1p/2p. In the present work, we demonstrate that Yno1p-derived H₂O₂ regulates outputs controlled by three MAP kinase pathways that can share components: the filamentous growth (filamentous growth MAPK (fMAPK)), pheromone response, and osmotic stress response (hyperosmolarity glycerol response, HOG) pathways. A key structural component and regulator in this process is the actin cytoskeleton. The nucleation and stabilization of actin are regulated by Yno1p. Cells lacking YNO1 showed reduced invasive growth, which could be reversed by stimulation of actin nucleation. Additionally, under osmotic stress, the vacuoles of a ∆yno1 strain show an enhanced fragmentation. During pheromone response induced by the addition of alpha-factor, Yno1p is responsible for a burst of ROS. Collectively, these results broaden the roles of ROS to encompass microbial differentiation responses and stress responses controlled by MAPK pathways.

Protective effects of luteolin on the venous endothelium

Luteolin is a flavonoid with antioxidant properties already demonstrated in studies related to inflammation, tumor, and cardiovascular processes; however, there are no available information regarding its antioxidant effects at the venous endothelial site. We investigated the effects of luteolin (10, 20, and 50 μmol/L) in cultures of rat venous endothelial cells. Nitric oxide (NO) and reactive oxygen species (ROS) were analyzed by fluorimetry; 3-nitrotyrosine (3-NT) residues were evaluated by immunofluorescence, and prostacyclin (PGI₂) release was investigated by colorimetry. Intracellular NO levels were significantly enhanced after 10 min of luteolin incubation, with a parallel decrease in ROS generation. These results were accompanied by a significant reduction in the expression of 3-NT residues and enhanced PGI₂ rates. Therefore, luteolin is effective in reducing ROS thereby improving NO availability in venous endothelial cells. Besides, luteolin-induced decrease in 3-NT residues may correlate with the enhancement in endothelial PGI₂ bioavailability. These findings suggest the future application of this flavonoid as a protective agent by improving endothelial function in several circulatory disorders related to venous insufficiency.

Design, synthesis and antitumour evaluation of novel anthraquinone derivatives

We report the design, synthesis, and biological evaluation of 13 new and 1 known anthraquinone derivatives which exerted cytotoxicity against PC3, A549 and NTUB1 cell lines. The results indicate that, among these 14, compounds-1 and 14 showed the highest growth inhibitory effect on NTUB1 and PC3 cells, respectively. Compound-1 at lower doses targets DNA, induces DNA damage and subsequently triggers G2/M arrest and apoptotic cell death at 24 h. Previously we reported that 14 induced PC3 cell autophagy and in treated PC3 cells, cleaved caspase-3 and cleaved PARP, and survivin did not increase and increase, respectively. The autophagic and necrotic cell deaths mediated by 14-triggered ROS generation. Our study is the first to investigate the biological mechanism of 14 action in detail. We find that when 14 was co-administrated with Bafilomycin A1 (BAF) in PC3 cells, rapid necrotic cell death occurred with no cleaved caspase-3 and cleaved PARP activation and increasing the expression of survivin. We further show that necrotic signaling in these cells coincided with production of reactive oxygen species. In the present study, we developed methods to synthesize five new 14 analogues for studing the structure-activity relationships. This study could provide valuable sight to find new antitumor agents for cancer therapy.

Restoring mitochondrial superoxide levels with elamipretide (MTP-131) protects db/db mice against progression of diabetic kidney disease

Exposure to chronic hyperglycemia because of diabetes mellitus can lead to development and progression of diabetic kidney disease (DKD). We recently reported that reduced superoxide production is associated with mitochondrial dysfunction in the kidneys of mouse models of type 1 DKD. We also demonstrated that humans with DKD have significantly reduced levels of mitochondrion-derived metabolites in their urine. Here we examined renal superoxide production in a type 2 diabetes animal model, the db/db mouse, and the role of a mitochondrial protectant, MTP-131 (also called elamipretide, SS-31, or Bendavia) in restoring renal superoxide production and ameliorating DKD. We found that 18-week-old db/db mice have reduced renal and cardiac superoxide levels, as measured by dihydroethidium oxidation, and increased levels of albuminuria, mesangial matrix accumulation, and urinary H2O2 Administration of MTP-131 significantly inhibited increases in albuminuria, urinary H2O2, and mesangial matrix accumulation in db/db mice and fully preserved levels of renal superoxide production in these mice. MTP-131 also reduced total renal lysocardiolipin and major lysocardiolipin subspecies and preserved lysocardiolipin acyltransferase 1 expression in db/db mice. These results indicate that, in type 2 diabetes, DKD is associated with reduced renal and cardiac superoxide levels and that MTP-131 protects against DKD and preserves physiological superoxide levels, possibly by regulating cardiolipin remodeling.

Pkm2 Regulates Cardiomyocyte Cell Cycle and Promotes Cardiac Regeneration

BACKGROUND

The adult mammalian heart has limited regenerative capacity, mostly attributable to postnatal cardiomyocyte cell cycle arrest. In the last 2 decades, numerous studies have explored cardiomyocyte cell cycle regulatory mechanisms to enhance myocardial regeneration after myocardial infarction. Pkm2 (Pyruvate kinase muscle isoenzyme 2) is an isoenzyme of the glycolytic enzyme pyruvate kinase. The role of Pkm2 in cardiomyocyte proliferation, heart development, and cardiac regeneration is unknown.

METHODS

We investigated the effect of Pkm2 in cardiomyocytes through models of loss (cardiomyocyte-specific Pkm2 deletion during cardiac development) or gain using cardiomyocyte-specific Pkm2 modified mRNA to evaluate Pkm2 function and regenerative affects after acute or chronic myocardial infarction in mice.

RESULTS

Here, we identify Pkm2 as an important regulator of the cardiomyocyte cell cycle. We show that Pkm2 is expressed in cardiomyocytes during development and immediately after birth but not during adulthood. Loss of function studies show that cardiomyocyte-specific Pkm2 deletion during cardiac development resulted in significantly reduced cardiomyocyte cell cycle, cardiomyocyte numbers, and myocardial size. In addition, using cardiomyocyte-specific Pkm2 modified RNA, our novel cardiomyocyte-targeted strategy, after acute or chronic myocardial infarction, resulted in increased cardiomyocyte cell division, enhanced cardiac function, and improved long-term survival. We mechanistically show that Pkm2 regulates the cardiomyocyte cell cycle and reduces oxidative stress damage through anabolic pathways and β-catenin.

CONCLUSIONS

We demonstrate that Pkm2 is an important intrinsic regulator of the cardiomyocyte cell cycle and oxidative stress, and highlight its therapeutic potential using cardiomyocyte-specific Pkm2 modified RNA as a gene delivery platform.

Tracking isotopically labeled oxidants using boronate-based redox probes

Reactive oxygen and nitrogen species have been implicated in many biological processes and diseases, including immune responses, cardiovascular dysfunction, neurodegeneration, and cancer. These chemical species are short-lived in biological settings, and detecting them in these conditions and diseases requires the use of molecular probes that form stable, easily detectable, products. The chemical mechanisms and limitations of many of the currently used probes are not well-understood, hampering their effective applications. Boronates have emerged as a class of probes for the detection of nucleophilic two-electron oxidants. Here, we report the results of an oxygen-18-labeling MS study to identify the origin of oxygen atoms in the oxidation products of phenylboronate targeted to mitochondria. We demonstrate that boronate oxidation by hydrogen peroxide, peroxymonocarbonate, hypochlorite, or peroxynitrite involves the incorporation of oxygen atoms from these oxidants. We therefore conclude that boronates can be used as probes to track isotopically labeled oxidants. This suggests that the detection of specific products formed from these redox probes could enable precise identification of oxidants formed in biological systems. We discuss the implications of these results for understanding the mechanism of conversion of the boronate-based redox probes to oxidant-specific products.

Norepinephrine Induces Lung Microvascular Endothelial Cell Death by NADPH Oxidase-Dependent Activation of Caspase-3

Norepinephrine (NE) is the naturally occurring adrenergic agonist that is released in response to hypotension, and it is routinely administered in clinical settings to treat moderate to severe hypotension that may occur during general anesthesia and shock states. Although NE has incontestable beneficial effects on blood pressure maintenance during hypotensive conditions, deleterious effects of NE on endothelial cell function may occur. In particular, the role of reactive oxygen species (ROS) and NADPH oxidase (Nox) on the deleterious effects of NE on endothelial cell function have not been fully elucidated. Therefore, we investigated the effects of NE on ROS production in rat lung microvascular endothelial cells (RLMEC) and its contribution to cell death. RLMEC were treated with NE (5 ng/mL) for 24 hours and ROS production was assessed by CellROX and DCFDA fluorescence. Nox activity was assessed by NADPH-stimulated ROS production in isolated membranes and phosphorylation of p47phox; cell death was assessed by flow cytometry and DNA fragmentation. Caspase activation was assessed by fluorescent microscopy. Nox1, Nox2, and Nox4 mRNA expression was assessed by real-time PCR. NE increased ROS production, Nox activity, p47phox phosphorylation, Nox2 and Nox4 mRNA content, caspase-3 activation, and RLMEC death. Phentolamine, an α₁-adrenoreceptor antagonist, inhibited NE-induced ROS production and Nox activity and partly inhibited cell death while β-blockade had no effect. Apocynin and PEGSOD inhibited NE-induced caspase-3 activation and cell death while direct inhibition of caspase-3 abrogated NE-induced cell death. PEG-CAT inhibited NE-induced cell death but not caspase-3 activation. Collectively, these results indicate that NE induces RLMEC death via activation of Nox by α-adrenergic signaling and caspase-3-dependent pathways. NE has deleterious effects on RLMECs that may be important to its long-term therapeutic use.

Hyperbaric oxygenation improves redox control and reduces mortality in the acute phase of myocardial infarction in a rat model

Among the mechanisms of action of hyperbaric oxygenation (HBO), the chance of reducing injury by interfering with the mechanisms of redox homeostasis in the heart leads to the possibility of extending the period of viability of the myocardium at risk. This would benefit late interventions for reperfusion to the ischemic area. The objective of the present study was to investigate the changes in the redox system associated with HBO therapy maintained during the first hour after coronary occlusion in an acute myocardial infarction (MI) rat model. Surviving male rats (n=105) were randomly assigned to one of three groups: Sham (SH=26), myocardial infarction (MI=45) and infarction+hyperbaric therapy (HBO=34, 1 h at 2.5 atm). After 90 min of coronary occlusion, a sample of the heart was collected for western blot analysis of total protein levels of superoxide dismutase, catalase, peroxiredoxin and 3‑nitrotyrosine. Glutathione was measured by enzyme‑linked immunosorbent assay (ELISA). The detection of the superoxide radical anion was carried out by oxidation of dihydroethidium analyzed with confocal microscopy. The mortality rate of the MI group was significantly higher than that of the HBO group. No difference was noted in the myocardial infarction size. The oxidized/reduced glutathione ratio and peroxiredoxin were significantly higher in the SH and MI when compared to the HBO group. Superoxide dismutase enzymes and catalase were significantly higher in the HBO group compared to the MI and SH groups. 3‑Nitrotyrosine and the superoxide radical were significantly lower in the HBO group compared to these in the MI and SH groups. These data demonstrated that hyperbaric oxygenation therapy decreased mortality by improving redox control in the hearts of rats in the acute phase of myocardial infarction.

Agonism of GPR120 prevents ox-LDL-induced attachment of monocytes to endothelial cells

Oxidized low-density lipoprotein (ox-LDL)-induced endothelial inflammation plays an important role in the development of cardiovascular diseases. G protein-coupled receptors (GPCR) are gaining traction as potential treatment targets due to their roles in mediating a wide range of physiological processes. GPR120 is a recently identified omega-3 fatty acid receptor. We hypothesized that agonism of GPR120 might attenuate ox-LDL-induced endothelial dysfunction. In the present study, we tested the effects of two GPR120 agonists-GW9508 and TUG-891-in mitigating endothelial insult induced by ox-LDL in human aortic endothelial cells (HAECs). Real-time PCR, western blot, and ELISA analyses were used in our experiments. Our findings demonstrate that GPR120 is downregulated by exposure to ox-LDL, suggesting a role for GPR120 in mediating ox-LDL insult. Furthermore, we found that agonism of GPR120 could suppress oxidative stress and inflammation by inhibiting the production of reactive oxygen species and the expression of proinflammatory cytokines. Importantly, we show that agonism of GPR120 prevents the attachment of monocytes to endothelial cells by suppressing the expression of VCAM-1 and E-selectin. Finally, we show that agonism of GPR120 exerts a remarkable atheroprotective effect by elevating the expression level of Krüppel-like factor 2 (KLF2). Together, our results demonstrate a potential role for specific agonism of GPR120 in the prevention of endothelial damages induced by ox-LDL.

Biotin attenuation of oxidative stress, mitochondrial dysfunction, lipid metabolism alteration and 7β-hydroxycholesterol-induced cell death in 158N murine oligodendrocytes

Mitochondrial dysfunction and oxidative stress are involved in neurodegenerative diseases associated with an enhancement of lipid peroxidation products such as 7β-hydroxycholesterol (7β-OHC). It is, therefore, important to study the ability of 7β-OHC to trigger mitochondrial defects, oxidative stress, metabolic dysfunctions and cell death, which are hallmarks of neurodegeneration, and to identify cytoprotective molecules. The effects of biotin were evaluated on 158N murine oligodendrocytes, which are myelin synthesizing cells, exposed to 7β-OHC (50 µM) with or without biotin (10 and 100 nM) or α-tocopherol (positive control of cytoprotection). The effects of biotin on 7β-OHC activities were determined using different criteria: cell adhesion; plasma membrane integrity; redox status. The impact on mitochondria was characterized by the measurement of transmembrane mitochondrial potential (ΔΨm), reactive oxygen species (ROS) overproduction, mitochondrial mass, quantification of cardiolipins and organic acids. Sterols and fatty acids were also quantified. Cell death (apoptosis, autophagy) was characterized by the enumeration of apoptotic cells, caspase-3 activation, identification of autophagic vesicles, and activation of LC3-I into LC3-II. Biotin attenuates 7β-OHC-induced cytotoxicity: loss of cell adhesion was reduced; antioxidant activities were normalized. ROS overproduction, protein and lipid oxidation products were decreased. Biotin partially restores mitochondrial functions: attenuation of the loss of ΔΨm; reduced levels of mitochondrial O₂^•- overproduction; normalization of cardiolipins and organic acid levels. Biotin also normalizes cholesterol and fatty acid synthesis, and prevents apoptosis and autophagy (oxiapoptophagy). Our data support that biotin, which prevents oligodendrocytes damages, could be useful in the treatment of neurodegeneration and demyelination.

Induction of a non-apoptotic mode of cell death associated with autophagic characteristics with steroidal maleic anhydrides and 7β-hydroxycholesterol on glioma cells

Steroidal maleic anhydrides were prepared in one step: lithocholic, chenodeoxicholic, deoxicholic, ursocholic, and hyodeoxicholic acid derivatives. Their capability to induce cell death was studied on C6 rat glioma cells, and 7β-hydroxycholesterol was used as positive cytotoxic control. The highest cytotoxicity was observed with lithocholic and chenodeoxicholic acid derivatives (23-(4-methylfuran-2,5-dione)-3α-hydroxy-24-nor-5β-cholane (compound 1a), and 23-(4-methylfuran-2,5-dione)-3α,7α-dihydroxy-24-nor-5β-cholane (compound 1b), respectively), which induce a non-apoptotic mode of cell death associated with mitochondrial membrane potential loss and reactive oxygen species overproduction. No cells with condensed and/or fragmented nuclei, no PARP degradation and no cleaved-caspase-3, which are apoptotic criteria, were observed. Similar effects were found with 7β-hydroxycholesterol. The cell clonogenic survival assay showed that compound 1b was more cytotoxic than compound 1a and 7β-hydroxycholesterol. Compound 1b and 7β-hydroxycholesterol also induce cell cycle modifications. In addition, compounds 1a and 1b, and 7β-hydroxycholesterol favour the formation of large acidic vacuoles revealed by staining with acridine orange and monodansylcadaverine evocating autophagic vacuoles; they also induce an increased ratio of [LC3-II / LC3-I], and modify the expression of mTOR, Beclin-1, Atg12, and Atg5-Atg12 which is are autophagic criteria. The ratio [LC3-II / LC3-I] is also strongly modified by bafilomycin acting on the autophagic flux. Rapamycin, an autophagic inducer, and 3-methyladenine, an autophagic inhibitor, reduce and increase 7β-hydroxycholesterol-induced cell death, respectively, supporting that 7β-hydroxycholesterol induces survival autophagy. Alpha-tocopherol also strongly attenuates 7β-hydroxycholesterol-induced cell death. However, rapamycin, 3-methyladenine, and α-tocopherol have no effect on compounds 1a and 1b-induced cell death. It is concluded that these compounds trigger a non apoptotic mode of cell death, involving the mitochondria and associated with several characteristics of autophagy.

Oxidative Stress in Retinal Degeneration Promoted by Constant LED Light

Light pollution by artificial light, might accelerate retinal diseases and circadian asynchrony. The excess of light exposure is a growing problem in societies, so studies on the consequences of long-term exposure to low levels of light are needed to determine the effects on vision. The possibility to understand the molecular mechanisms of light damage will contribute to the knowledge about visual disorders related to defects in the phototransduction. Several animal models have been used to study retinal degeneration (RD) by light; however, some important aspects remain to be established. Previously, we demonstrated that cool white treatment of 200 lux light-emitting diode (LED) induces retinal transformation with rods and cones cell death and significant changes in opsin expression in the inner nuclear layer (INL) and ganglion cell layer (GCL). Therefore, to further develop describing the molecular pathways of RD, we have examined here the oxidative stress and the fatty acid composition in rat retinas maintained at constant light. We demonstrated the existence of oxidative reactions after 5 days in outer nuclear layer (ONL), corresponding to classical photoreceptors; catalase (CAT) enzyme activity did not show significant differences in all times studied and the fatty acid study showed that docosahexaenoic acid decreased after 4 days. Remarkably, the docosahexaenoic acid diminution showed a correlation with the rise in stearic acid indicating a possible association between them. We assumed that the reduction in docosahexaenoic acid may be affected by the oxidative stress in photoreceptors outer segment which in turn affects the stearic acid composition with consequences in the membrane properties. All these miss-regulation affects the photoreceptor survival through unknown mechanisms involved. We consider that oxidative stress might be one of the pathways implicated in RD promoted by light.

Critical Role of the Interaction Gut Microbiota - Sympathetic Nervous System in the Regulation of Blood Pressure

Association between gut dysbiosis and neurogenic diseases, such as hypertension, has been described. The aim of this study was to investigate whether changes in the gut microbiota alter gut-brain interactions inducing changes in blood pressure (BP). Recipient normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) were orally gavaged with donor fecal contents from SHR and WKY. We divided the animals into four groups: WKY transplanted with WKY microbiota (W-W), SHR with SHR (S-S), WKY with SHR (W-S) and SHR with WKY (S-W). Basal systolic BP (SBP) and diastolic BP (DBP) were reduced with no change in heart rate as a result of fecal microbiota transplantation (FMT) from WKY rats to SHR. Similarly, FMT from SHR to WKY increased basal SBP and DBP. Increases in both NADPH oxidase-driven reactive oxygen species production and proinflammatory cytokines in brain paraventricular nucleus linked to higher BP drop with pentolinium and plasmatic noradrenaline (NA) levels were found in the S-S group as compared to the W-W group. These parameters were reduced by FMT from WKY to SHR. Increased levels of pro-inflammatory cytokines, tyrosine hydroxylase mRNA levels and NA content in the proximal colon, whereas reduced mRNA levels of gap junction proteins, were found in the S-S group as compared to the W-W group. These changes were inhibited by FMT from WKY to SHR. According to our correlation analyses, the abundance of Blautia and Odoribacter showed a negative correlation with high SBP. In conclusion, in SHR gut microbiota is an important factor involved in BP control, at least in part, as consequence of its effect on neuroinflammation and the sympathetic nervous system activity.

Subverted regulation of Nox1 NADPH oxidase-dependent oxidant generation by protein disulfide isomerase A1 in colon carcinoma cells with overactivated KRas

Protein disulfide isomerases including PDIA1 are implicated in cancer progression, but underlying mechanisms are unclear. PDIA1 is known to support vascular Nox1 NADPH oxidase expression/activation. Since deregulated reactive oxygen species (ROS) production underlies tumor growth, we proposed that PDIA1 is an upstream regulator of tumor-associated ROS. We focused on colorectal cancer (CRC) with distinct KRas activation levels. Analysis of RNAseq databanks and direct validation indicated enhanced PDIA1 expression in CRC with constitutive high (HCT116) vs. moderate (HKE3) and basal (Caco2) Ras activity. PDIA1 supported Nox1-dependent superoxide production in CRC; however, we first reported a dual effect correlated with Ras-level activity: in Caco2 and HKE3 cells, loss-of-function experiments indicate that PDIA1 sustains Nox1-dependent superoxide production, while in HCT116 cells PDIA1 restricted superoxide production, a behavior associated with increased Rac1 expression/activity. Transfection of Rac1^G12V active mutant into HKE3 cells induced PDIA1 to become restrictive of Nox1-dependent superoxide, while in HCT116 cells treated with Rac1 inhibitor, PDIA1 became supportive of superoxide. PDIA1 silencing promoted diminished cell proliferation and migration in HKE3, not detectable in HCT116 cells. Screening of cell signaling routes affected by PDIA1 silencing highlighted GSK3β and Stat3. Also, E-cadherin expression after PDIA1 silencing was decreased in HCT116, consistent with PDIA1 support of epithelial–mesenchymal transition. Thus, Ras overactivation switches the pattern of PDIA1-dependent Rac1/Nox1 regulation, so that Ras-induced PDIA1 bypass can directly activate Rac1. PDIA1 may be a crucial regulator of redox-dependent adaptive processes related to cancer progression.

HPLC-Based Monitoring of Oxidation of Hydroethidine for the Detection of NADPH Oxidase-Derived Superoxide Radical Anion

Hydroethidine is a fluorogenic probe that in the presence of the superoxide radical anion is oxidized to a red fluorescent product, 2-hydroxyethidium. In cells, hydroethidine is also oxidized to other products, including red fluorescent ethidium. Thus, selective monitoring of 2-hydroxyethidium is required for specific detection of the superoxide radical anion. Here, we provide protocols for HPLC- and LC-MS-based quantitation of 2-hydroxyethidium, among other oxidation products. Also, a protocol for continuous sampling for real-time monitoring of superoxide production using rapid HPLC measurements of 2-hydroxyethidium is described.

Peri/epicellular protein disulfide isomerase-A1 acts as an upstream organizer of cytoskeletal mechanoadaptation in vascular smooth muscle cells

Although redox processes closely interplay with mechanoresponses to control vascular remodeling, redox pathways coupling mechanostimulation to cellular cytoskeletal organization remain unclear. The peri/epicellular pool of protein disulfide isomerase-A1 (pecPDIA1) supports postinjury vessel remodeling. Using distinct models, we investigated whether pecPDIA1 could work as a redox-dependent organizer of cytoskeletal mechanoresponses. In vascular smooth muscle cells (VSMCs), pecPDIA1 immunoneutralization impaired stress fiber assembly in response to equibiaxial stretch and, under uniaxial stretch, significantly perturbed cell repositioning perpendicularly to stretch orientation. During cyclic stretch, pecPDIA1 supported thiol oxidation of the known mechanosensor β₁-integrin and promoted polarized compartmentalization of sulfenylated proteins. Using traction force microscopy, we showed that pecPDIA1 organizes intracellular force distribution. The net contractile moment ratio of platelet-derived growth factor-exposed to basal VSMCs decreased from 0.90 ± 0.09 (IgG-exposed controls) to 0.70 ± 0.08 after pecPDI neutralization ( P < 0.05), together with an enhanced coefficient of variation for distribution of force modules, suggesting increased noise. Moreover, in a single cell model, pecPDIA1 neutralization impaired migration persistence without affecting total distance or velocity, whereas siRNA-mediated total PDIA1 silencing disabled all such variables of VSMC migration. Neither expression nor total activity of the master mechanotransmitter/regulator RhoA was affected by pecPDIA1 neutralization. However, cyclic stretch-induced focal distribution of membrane-bound RhoA was disrupted by pecPDI inhibition, which promoted a nonpolarized pattern of RhoA/caveolin-3 cluster colocalization. Accordingly, FRET biosensors showed that pecPDIA1 supports localized RhoA activity at cell protrusions versus perinuclear regions. Thus, pecPDI acts as a thiol redox-dependent organizer and noise reducer mechanism of cytoskeletal repositioning, oxidant generation, and localized RhoA activation during a variety of VSMC mechanoresponses. NEW & NOTEWORTHY Effects of a peri/epicellular pool of protein disulfide isomerase-A1 (pecPDIA1) during mechanoregulation in vascular smooth muscle cells (VSMCs) were highlighted using approaches such as equibiaxial and uniaxial stretch, random single cell migration, and traction force microscopy. pecPDIA1 regulates organization of the cytoskeleton and minimizes the noise of cell alignment, migration directionality, and persistence. pecPDIA1 mechanisms involve redox control of β₁-integrin and localized RhoA activation. pecPDIA1 acts as a novel organizer of mechanoadaptation responses in VSMCs.

Lipid damage is the best marker of oxidative injury during the cardiac remodeling process induced by tobacco smoke

BACKGROUND

Oxidative stress is one potential mechanism that explain the direct effects of smoking on cardiac remodeling process. However, no study has compared different myocardial products of macromolecule oxidation after tobacco smoke exposure. Thus, the aim of this study was to investigate the lipid hydroperoxide (LH) levels, protein carbonyl concentrations and DNA damage in cardiac tissue of rats exposed to tobacco smoke.

METHODS

Male Wistar rats were divided into two groups: group C (control, n = 14) composed of animals not exposed to cigarette smoke; group ETS (exposed to tobacco smoke, n = 14) composed by animals exposed to cigarette smoke. The animals were exposed to 2 month of ETS and morphological, biochemical and functional analyses were performed.

RESULTS

Cardiac cotinine levels were elevated in the ETS group. In addition, the myocyte cross-sectional area was higher in the ETS group. (C = 266.6 ± 23.2 μm2 and ETS = 347.5 ± 15.1 μm2, p <  0.001). Cardiac LH was higher in the ETS group than in group C (C = 196.4 ± 51.5 nmol/g and ETS = 331.9 ± 52.9 nmol/g, p <  0.001). However, there were no between-group differences in cardiac protein carbonyl concentration or DNA damage.

CONCLUSIONS

Therefore, our results suggest that, in this model, lipid damage is a good marker of oxidative damage during the cardiac remodeling process induced by 2 months of exposure to tobacco smoke.

Stimulatory TSH-Receptor Antibodies and Oxidative Stress in Graves Disease

CONTEXT

We hypothesized that TSH-receptor (TSHR) stimulating antibodies (TSAbs) are involved in oxidative stress mechanisms in patients with Graves disease (GD).

METHODS

Nicotinamide adenine dinucleotide phosphate oxidase, isoform 2 (NOX2); oxidative parameters; and oxidative burst were measured in serum, urine, and whole blood from patients with GD and control subjects. Superoxide production was investigated in human embryonic kidney (HEK)-293 cells stably overexpressing the TSHR. Lipid peroxidation was determined by immunodot-blot analysis for protein-bound 4-hydroxy-2-nonenal (4-HNE) in human primary thyrocytes and HEK-293-TSHR cells.

RESULTS

Serum NOX2 levels were markedly higher in hyperthyroid untreated vs euthyroid treated patients with GD, hyperthyroid patients with toxic nodular goiter, and euthyroid healthy control subjects (all P < 0.0001). Urine oxidative parameters were increased in patients with GD vs patients with toxic goiter (P < 0.01) and/or control subjects (P < 0.001). The maximum of the zymosan A- and phorbol 12,13-dibutyrate-induced respiratory burst of leukocytes was 1.5-fold higher in whole blood from hyperthyroid patients with GD compared with control subjects (P < 0.001 and P < 0.05). Monoclonal M22 TSAbs stimulated cAMP (HEK cells) in a dose-dependent manner. M22 (P = 0.0082), bovine TSH (P = 0.0028), and sera of hyperthyroid patients with GD (P < 0.05) increased superoxide-specific 2-hydroxyethidium levels in HEK-293 TSHR cells after 48-hour incubation vs control subjects. In contrast, triiodothyronine (T3) did not affect reactive oxygen species (ROS) production. In primary thyrocytes, the 4-HNE marker was higher in patients with GD vs control subjects at 6 and 48 hours (P = 0.02 and P = 0.04, respectively). Further, after 48-hour incubation of HEK-293 TSHR cells with patient sera, 4-HNE was higher in patients with untreated GD compared with control subjects (P < 0.05).

CONCLUSIONS

Monoclonal M22 and polyclonal serum TSAbs augment ROS generation and/or induce lipid peroxidation.

Myostatin knockout induces apoptosis in human cervical cancer cells via elevated reactive oxygen species generation

Myostatin (Mstn) is postulated to be a key determinant of muscle loss and cachexia in cancer. However, no experimental evidence supports a role for Mstn in cancer, particularly in regulating the survival and growth of cancer cells. In this study, we showed that the expression of Mstn was significantly increased in different tumor tissues and human cancer cells. Mstn knockdown inhibited the proliferation of cancer cells. A knockout (KO) of Mstn created by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) 9 (CRISPR/Cas9) induced mitochondria-dependent apoptosis in HeLa cells. Furthermore, KO of Mstn reduced the lipid content. Molecular analyses demonstrated that the expression levels of fatty acid oxidation-related genes were upregulated and then increased rate of fatty acid oxidation. Mstn deficiency-induced apoptosis took place along with generation of reactive oxygen species (ROS) and elevated fatty acid oxidation, which may play a role in triggering mitochondrial membrane depolarization, the release of cytochrome c (Cyt-c), and caspase activation. Importantly, apoptosis induced by Mstn KO was partially rescued by antioxidants and etomoxir, thereby suggesting that the increased level of ROS was functionally involved in mediating apoptosis. Overall, our findings demonstrate a novel function of Mstn in regulating mitochondrial metabolism and apoptosis within cancer cells. Hence, inhibiting the production and function of Mstn may be an effective therapeutic intervention during cancer progression and muscle loss in cachexia.

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Mstn is expressed in different tumor tissues and human cancer cells.

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Mstn knockdown inhibits the proliferation of cancer cells.

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Mstn KO induces mitochondria-dependent apoptosis in HeLa cells.

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Mstn KO increases the rate of fatty acid oxidation.

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ROS generation induces apoptosis in HeLa/Mstn KO cells.

Detection of Hydrogen Peroxide with Fluorescent Dyes

SIGNIFICANCE

Hydrogen peroxide (H₂O₂) is a powerful effector of redox signaling. It is able to oxidize cysteine residues, metal ion centers, and lipids. Understanding H₂O₂-mediated signaling requires, to some extent, measurement of H₂O₂ level. Recent Advances: Chemically and genetically encoded fluorescent probes for the detection of H₂O₂ are currently the most sensitive and popular. Novel probes are constantly being developed, with the latest progress particular with boronates and genetically encoded probes.

CRITICAL ISSUES

All currently available probes display limitations in terms of sensitivity, local and temporal resolution, and specificity in the detection of low H₂O₂ concentrations. In this review, we discuss the power of fluorescent probes and the systems in which they have been successfully employed. Moreover, we recommend approaches for overcoming probe limitations and for the avoidance of artifacts.

FUTURE DIRECTIONS

Constant improvements will lead to the generation of probes that are not only more sensitive but also specifically tailored to individual cellular compartments. Antioxid. Redox Signal. 29, 585-602.

Lactobacillus fermentum Improves Tacrolimus-Induced Hypertension by Restoring Vascular Redox State and Improving eNOS Coupling

SCOPE

The aim is to analyze whether the probiotic Lactobacillus fermentum CECT5716 (LC40) can prevent endothelial dysfunction and hypertension induced by tacrolimus in mice.

METHODS AND RESULTS

Tacrolimus increases systolic blood pressure (SBP) and impairs endothelium-dependent relaxation to acetylcholine and these effects are partially prevented by LC40. Endothelial dysfunction induced by tacrolimus is related to both increased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX2) and uncoupled endothelial nitric oxide synthase (eNOS)-driven superoxide production and Rho-kinase-mediated eNOS inhibition. LC40 treatment prevents all the aortic changes induced by tacrolimus. LC40 restores the imbalance between T-helper 17 (Th17)/regulatory T (Treg) cells induced by tacrolimus in mesenteric lymph nodes and the spleen. Tacrolimus-induced gut dysbiosis, that is, it decreases microbial diversity, increases the Firmicutes/Bacteroidetes (F/B) ratio and decreases acetate- and butyrate-producing bacteria, and these effects are prevented by LC40. Fecal microbiota transplantation (FMT) from LC40-treated mice to control mice prevents the increase in SBP and the impaired relaxation to acetylcholine induced by tacrolimus.

CONCLUSION

LC40 treatment prevents hypertension and endothelial dysfunction induced by tacrolimus by inhibiting gut dysbiosis. These effects are associated with a reduction in vascular oxidative stress, mainly through NOX2 downregulation and prevention of eNOS uncoupling, and inflammation possibly because of decreased Th17 and increased Treg cells polarization in mesenteric lymph nodes.

Detection and Characterization of Reactive Oxygen and Nitrogen Species in Biological Systems by Monitoring Species-Specific Products

SIGNIFICANCE

Since the discovery of the superoxide dismutase enzyme, the generation and fate of short-lived oxidizing, nitrosating, nitrating, and halogenating species in biological systems has been of great interest. Despite the significance of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in numerous diseases and intracellular signaling, the rigorous detection of ROS and RNS has remained a challenge. Recent Advances: Chemical characterization of the reactions of selected ROS and RNS with electron paramagnetic resonance (EPR) spin traps and fluorescent probes led to the establishment of species-specific products, which can be used for specific detection of several forms of ROS and RNS in cell-free systems and in cultured cells in vitro and in animals in vivo. Profiling oxidation products from the ROS and RNS probes provides a rigorous method for detection of those species in biological systems.

CRITICAL ISSUES

Formation and detection of species-specific products from the probes enables accurate characterization of the oxidative environment in cells. Measurement of the total signal (fluorescence, chemiluminescence, etc.) intensity does not allow for identification of the ROS/RNS formed. It is critical to identify the products formed by using chromatographic or other rigorous techniques. Product analyses should be accompanied by monitoring of the intracellular probe level, another factor controlling the yield of the product(s) formed.

FUTURE DIRECTIONS

More work is required to characterize the chemical reactivity of the ROS/RNS probes, and to develop new probes/detection approaches enabling real-time, selective monitoring of the specific products formed from the probes. Antioxid. Redox Signal. 28, 1416-1432.

The redox-sensing gene Nrf2 affects intestinal homeostasis, insecticide resistance, and Zika virus susceptibility in the mosquito Aedes aegypti

Production and degradation of reactive oxygen species (ROS) are extensively regulated to ensure proper cellular responses to various environmental stimuli and stresses. Moreover, physiologically generated ROS function as secondary messengers that can influence tissue homeostasis. The cap'n'collar transcription factor known as nuclear factor erythroid-derived factor 2 (Nrf2) coordinates an evolutionarily conserved transcriptional activation pathway that mediates antioxidant and detoxification responses in many animal species, including insects and mammals. Here, we show that Nrf2-mediated signaling affects embryo survival, midgut homeostasis, and redox biology in Aedes aegypti, a mosquito species vector of dengue, Zika, and other disease-causing viruses. We observed that AeNrf2 silencing increases ROS levels and stimulates intestinal stem cell proliferation. Because ROS production is a major aspect of innate immunity in mosquito gut, we found that a decrease in Nrf2 signaling results in reduced microbiota growth and Zika virus infection. Moreover, we provide evidence that AeNrf2 signaling also controls transcriptional adaptation of A. aegypti to insecticide challenge. Therefore, we conclude that Nrf2-mediated response regulates assorted gene clusters in A. aegypti that determine cellular and midgut redox balance, affecting overall xenobiotic resistance and vectorial adaptation of the mosquito.

Integrated molecular, biochemical, and physiological assessment unravels key extraction method mediated influences on rat neonatal cardiomyocytes

Neonatal cardiomyocytes are instrumental for disease modeling, but the effects of different cell extraction methods on basic cell biological processes remain poorly understood. We assessed the influence of two popular methods to extract rat neonatal cardiomyocytes, Pre-plating (PP), and Percoll (PC) on cell structure, metabolism, and function. Cardiomyocytes obtained from PP showed higher gene expression for troponins, titin, and potassium and sodium channels compared to PC. Also, PP cells displayed higher levels of troponin I protein. Cells obtained from PC displayed higher lactate dehydrogenase activity and lactate production than PP cells, indicating higher anaerobic metabolism after 8 days of culture. In contrast, reactive oxygen species levels were higher in PP cells as indicated by ethidium and hydroxyethidium production. Consistent with these data, protein nitration was higher in PP cells, as well as nitrite accumulation in cell medium. Moreover, PP cells showed higher global intracellular calcium under basal and 1 mM isoprenaline conditions. In a calcium-transient assessment under electrical stimulation (0.5 Hz), PP cells displayed higher calcium amplitude than cardiomyocytes obtained from PC and using a traction force microscope technique we observed that PP cardiomyocytes showed the highest relaxation. Collectively, we demonstrated that extraction methods influence parameters related to cell structure, metabolism, and function. Overall, PP derived cells are more active and mature than PC cells, displaying higher contractile function and generating more reactive oxygen species. On the other hand, PC derived cells display higher anaerobic metabolism, despite comparable high yields from both protocols.

Influence of apocynin on cardiac remodeling in rats with streptozotocin-induced diabetes mellitus

Background

Increased reactive oxygen species (ROS) generation in diabetes mellitus (DM) is an important mechanism leading to diabetic cardiomyopathy. Apocynin, a drug isolated from the herb Picrorhiza kurroa, is considered an antioxidant agent by inhibiting NADPH oxidase activity and improving ROS scavenging. This study analyzed the influence of apocynin on cardiac remodeling in diabetic rats.

Methods

Six-month-old male Wistar rats were assigned into 4 groups: control (CTL, n = 15), control + apocynin (CTL + APO, n = 20), diabetes (DM, n = 20), and diabetes + apocynin (DM + APO, n = 20). DM was induced by streptozotocin. Seven days later, apocynin (16 mg/kg/day) or vehicle was initiated and maintained for 8 weeks. Left ventricular (LV) histological sections were used to analyze interstitial collagen fraction. NADPH oxidase activity was evaluated in LV samples. Comparisons between groups were performed by ANOVA for a 2 × 2 factorial design followed by the Bonferroni post hoc test.

Results

Body weight (BW) was lower and glycemia higher in diabetic animals. Echocardiogram showed increased left atrial diameter, LV diastolic diameter, and LV mass indexed by BW in both diabetic groups; apocynin did not affect these indices. LV systolic function was impaired in DM groups and unchanged by apocynin. Isovolumic relaxation time was increased in DM groups; transmitral E/A ratio was higher in DM + APO compared to DM. Myocardial functional evaluation through papillary muscle preparations showed impaired contractile and relaxation function in both DM groups at baseline conditions. After positive inotropic stimulation, developed tension (DT) was lower in DM than CTL. In DM + APO, DT had values between those in DM and CTL + APO and did not significantly differ from either group. Myocardial interstitial collagen fraction was higher in DM than CTL and did not differ between DM + APO and CTL + APO. Serum activity of antioxidant enzymes glutathione peroxidase, superoxide dismutase (SOD), and catalase was lower in DM than CTL; apocynin restored catalase and SOD levels in DM + APO. Myocardial NADPH oxidase activity did not differ between groups.

Conclusion

Apocynin restores serum antioxidant enzyme activity despite unchanged myocardial NADPH oxidase activity in diabetic rats.

Augmentation of poly(ADP-ribose) polymerase-dependent neuronal cell death by acidosis

Tissue acidosis is a key component of cerebral ischemic injury, but its influence on cell death signaling pathways is not well defined. One such pathway is parthanatos, in which oxidative damage to DNA results in activation of poly(ADP-ribose) polymerase and generation of poly(ADP-ribose) polymers that trigger release of mitochondrial apoptosis-inducing factor. In primary neuronal cultures, we first investigated whether acidosis per sé is capable of augmenting parthanatos signaling initiated pharmacologically with the DNA alkylating agent, N-methyl- N'-nitro- N-nitrosoguanidine. Exposure of neurons to medium at pH 6.2 for 4 h after N-methyl- N'-nitro- N-nitrosoguanidine washout increased intracellular calcium and augmented the N-methyl- N'-nitro- N-nitrosoguanidine-evoked increase in poly(ADP-ribose) polymers, nuclear apoptosis-inducing factor , and cell death. The augmented nuclear apoptosis-inducing factor and cell death were blocked by the acid-sensitive ion channel-1a inhibitor, psalmotoxin. In vivo, acute hyperglycemia during transient focal cerebral ischemia augmented tissue acidosis, poly(ADP-ribose) polymers formation, and nuclear apoptosis-inducing factor , which was attenuated by a poly(ADP-ribose) polymerase inhibitor. Infarct volume from hyperglycemic ischemia was decreased in poly(ADP-ribose) polymerase 1-null mice. Collectively, these results demonstrate that acidosis can directly amplify neuronal parthanatos in the absence of ischemia through acid-sensitive ion channel-1a . The results further support parthanatos as one of the mechanisms by which ischemia-associated tissue acidosis augments cell death.

Increased monocyte-derived reactive oxygen species in type 2 diabetes: role of endoplasmic reticulum stress

NEW FINDINGS

What is the central question of this study? Patients with type 2 diabetes exhibit increased oxidative stress in peripheral blood mononuclear cells, including monocytes; however, the mechanisms remain unknown. What is the main finding and its importance? The main finding of this study is that factors contained within the plasma of patients with type 2 diabetes can contribute to increased oxidative stress in monocytes, making them more adherent to endothelial cells. We show that these effects are largely mediated by the interaction between endoplasmic reticulum stress and NADPH oxidase activity. Recent evidence suggests that exposure of human monocytes to glucolipotoxic media to mimic the composition of plasma of patients with type 2 diabetes (T2D) results in the induction of endoplasmic reticulum (ER) stress markers and formation of reactive oxygen species (ROS). The extent to which these findings translate to patients with T2D remains unclear. Thus, we first measured ROS (dihydroethidium fluorescence) in peripheral blood mononuclear cells (PBMCs) from whole blood of T2D patients (n = 8) and compared the values with age-matched healthy control subjects (n = 8). The T2D patients exhibited greater basal intracellular ROS (mean ± SD, +3.4 ± 1.4-fold; P < 0.05) compared with control subjects. Next, the increase in ROS in PBMCs isolated from T2D patients was partly recapitulated in cultured human monocytes (THP-1 cells) exposed to plasma from T2D patients for 36 h (+1.3 ± 0.08-fold versus plasma from control subjects; P < 0.05). In addition, we found that increased ROS formation in THP-1 cells treated with T2D plasma was NADPH oxidase derived and led to increased endothelial cell adhesion (+1.8 ± 0.5-fold; P < 0.05) and lipid uptake (+1.3 ± 0.3-fold; P < 0.05). Notably, we found that T2D plasma-induced monocyte ROS and downstream functional effects were abolished by treating cells with tauroursodeoxycholic acid, a chemical chaperone known to inhibit ER stress. Collectively, these data indicate that monocyte ROS production with T2D can be attributed, in part, to signals from the circulating environment. Furthermore, an interplay between ER stress and NADPH oxidase activity contributes to ROS production and may be a mechanism mediating endothelial cell adhesion and foam cell formation in T2D.

Measurement of Superoxide Production and NADPH Oxidase Activity by HPLC Analysis of Dihydroethidium Oxidation

The fluorogenic probe dihydroethidium (DHE) is widely used for detecting intracellular superoxide. DHE oxidation by superoxide generates specifically the compound 2-hydroxyethidium (2-E⁺OH), so that 2-E⁺OH detection confers specificity to superoxide assessment among many other reactive oxygen species. However, DHE oxidation in biological systems leads to formation of other fluorescent products, particularly ethidium, usually formed at higher quantities than 2-E⁺OH. Since both 2-E⁺OH and ethidium are fluorescent, their identification and quantification is possible only after their physical separation by HPLC. Here we describe the detailed procedures for superoxide measurement in cells (adhered or not) and fresh tissues fragments, followed by acetonitrile extraction and simultaneous fluorescent detection of 2-E⁺OH and ethidium and absorbance detection of remaining unreacted DHE. In addition we report the use of DHE/HPLC for measuring NADPH oxidase activity in enriched-membrane fraction isolated from cells or tissues. These methods can improve accuracy and precision of quantitative superoxide measurements in biological samples.

Multimodality Imaging of Cancer Superoxide Anion Using the Small Molecule Coelenterazine

PURPOSE

We evaluated the small molecule coelenterazine as a potential reporter of cancer-associated superoxide anion in cell culture and in mice.

PROCEDURES

The superoxide anion concentrations of various cancer cell lines were quantified by coelenterazine chemiluminescence in vitro. Coelenteramide fluorescence was detected via flow cytometry and fluorescent microscopy. Coelenterazine was used for the in vivo detection of cancer-associated superoxide anion using the 4T1 breast adenocarcinoma mouse model.

RESULTS

Various cell lines in culture demonstrated different superoxide anion concentrations, with a signal range of 3.15 ± 0.06 to 11.80 ± 0.24 times that of background. In addition to chemiluminescent detection of coelenterazine, we demonstrated fluorescent detection of coelenteramide within the cytoplasm of cells. 4T1 murine mammary adenocarcinoma tumors in mice demonstrated significantly higher 2.13 ± 0.19-fold coelenterazine-based chemiluminescence than that of surrounding normal tissues.

CONCLUSIONS

Collectively, our results indicate that coelenterazine can be used to assay superoxide anion concentrations in cultured cancer cells and in tumors growing in mice.

Long-Term Alteration of Reactive Oxygen Species Led to Multidrug Resistance in MCF-7 Cells

Reactive oxygen species (ROS) play an important role in multidrug resistance (MDR). This study aimed to investigate the effects of long-term ROS alteration on MDR in MCF-7 cells and to explore its underlying mechanism. Our study showed both long-term treatments of H₂O₂ and glutathione (GSH) led to MDR with suppressed iROS levels in MCF-7 cells. Moreover, the MDR cells induced by 0.1 μM H₂O₂ treatment for 20 weeks (MCF-7/ROS cells) had a higher viability and proliferative ability than the control MCF-7 cells. MCF-7/ROS cells also showed higher activity or content of intracellular antioxidants like glutathione peroxidase (GPx), GSH, superoxide dismutase (SOD), and catalase (CAT). Importantly, MCF-7/ROS cells were characterized by overexpression of MDR-related protein 1 (MRP1) and P-glycoprotein (P-gp), as well as their regulators NF-E2-related factor 2 (Nrf2), hypoxia-inducible factor 1 (HIF-1α), and the activation of PI3K/Akt pathway in upstream. Moreover, several typical MDR mediators, including glutathione S-transferase-π (GST-π) and c-Myc and Protein Kinase Cα (PKCα), were also found to be upregulated in MCF-7/ROS cells. Collectively, our results suggest that ROS may be critical in the generation of MDR, which may provide new insights into understanding of mechanisms of MDR.

Apocynin influence on oxidative stress and cardiac remodeling of spontaneously hypertensive rats with diabetes mellitus

PURPOSE

Although increased oxidative stress is a major component of diabetic hypertensive cardiomyopathy, research into the effects of antioxidants on cardiac remodeling remains scarce. The actions of antioxidant apocynin include inhibiting reactive oxygen species (ROS) generation by nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and ROS scavenging. We evaluated the effects of apocynin on cardiac remodeling in spontaneously hypertensive rats (SHR) with diabetes mellitus (DM).

METHODS

Male SHR were divided into four groups: control (SHR, n = 16); SHR treated with apocynin (SHR-APO; 16 mg/kg/day, added to drinking water; n = 16); diabetic SHR (SHR-DM, n = 13); and SHR-DM treated with apocynin (SHR-DM-APO, n = 14), for eight weeks. DM was induced by streptozotocin (40 mg/kg, single dose). Statistical analyzes: ANOVA and Tukey or Mann-Whitney.

RESULTS

Echocardiogram in diabetic groups showed higher left ventricular and left atrium diameters indexed for body weight, and higher isovolumetric relaxation time than normoglycemic rats; systolic function did not differ between groups. Isolated papillary muscle showed impaired contractile and relaxation function in diabetic groups. Developed tension was lower in SHR-APO than SHR. Myocardial hydroxyproline concentration was higher in SHR-DM than SHR, interstitial collagen fraction was higher in SHR-DM-APO than SHR-APO, and type III collagen protein expression was lower in SHR-DM and SHR-DM-APO than their controls. Type I collagen and lysyl oxidase expression did not differ between groups. Apocynin did not change collagen tissue. Myocardial lipid hydroperoxide concentration was higher in SHR-DM than SHR and SHR-DM-APO. Glutathione peroxidase activity was lower and catalase higher in SHR-DM than SHR. Apocynin attenuated antioxidant enzyme activity changes in SHR-DM-APO. Advanced glycation end-products and NADPH oxidase activity did not differ between groups.

CONCLUSION

Apocynin reduces oxidative stress independently of NADPH oxidase activity and does not change ventricular or myocardial function in spontaneously hypertensive rats with diabetes mellitus. The apocynin-induced myocardial functional impairment in SHR shows that apocynin actions need to be clarified during sustained chronic pressure overload.