Phase evolution, surface chemistry, and antimicrobial performance of Ni-incorporated vanadium pentoxide complex oxides

Nitric Oxide and Reactive Oxygen Species in PCD Signaling

Reactive oxygen species (ROS) and iron (Fe) metabolic pathways are linked. The first part of this chapter summarizes how Fe contributes to ROS production and elimination in cells. We review shortly how plants acquire Fe. Comparative transcriptomic datasets reflecting high Fe, low Fe, and very low Fe responses are scanned for differentially expressed genes encoding enzymes for ROS generation and scavenging as well as ROS signature genes. These genes are assembled and their expression patterns are discussed in light of the importance of ROS production under high and very low Fe. In the second part of this chapter, we highlight different areas of research questions revealing the regulatory interconnections between ROS and Fe signaling, namely NADPH oxidase signaling and heme breakdown, glutathione-based signaling, retrograde chloroplast, and Fe–S cluster signaling, ferroptosis and ROS marker ZAT12-mediated signaling.

Clinical and experimental evidence indicate that increased vascular permeability contributes to many disease-associated vascular complications. Oxidative stress with increased production of reactive oxygen species (ROS) has been implicated in a wide variety of pathological conditions, including inflammation and many cardiovascular diseases. It is thus important to identify the role of ROS and their mechanistic significance in microvessel barrier dysfunction under pathological conditions. The role of specific ROS and their cross talk in pathological processes is complex. The mechanisms of ROS-induced increases in vascular permeability remain poorly understood. The sources of ROS in diseases have been extensively reviewed at enzyme levels. This review will instead focus on the underlying mechanisms of ROS release by leukocytes, the differentiate effects and signaling mechanisms of individual ROS on endothelial cells, pericytes and microvessel barrier function, as well as the interplay of reactive oxygen species, nitric oxide, and nitrogen species in ROS-mediated vascular barrier dysfunction. As a counter balance of excessive ROS, nuclear factor erythroid 2 related factor 2 (Nrf2), a redox-sensitive cell-protective transcription factor, will be highlighted as a potential therapeutic target for antioxidant defenses. The advantages and limitations of different experimental approaches used for the study of ROS-induced endothelial barrier function are also discussed. This article will outline the advances emerged mainly from in vivo and ex vivo studies and attempt to consolidate some of the opposing views in the field, and hence provide a better understanding of ROS-mediated microvessel barrier dysfunction and benefit the development of therapeutic strategies.

Circulating levels of soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) play an important role in the development and progression of atherosclerosis. We hypothesized that the inflammatory marker C-reactive protein (CRP) might stimulate sLOX-1 release by activating tumor necrosis factor-α converting enzyme (TACE). Macrophages differentiated from THP-1 cells were stimulated with TNF-α and further treated with CRP in the absence or presence of specific inhibitors or small interfering RNA (siRNA). Our results showed that CRP increased sLOX-1 release from activated macrophages in a dose-dependent manner and that these effects were regulated by Fc γ receptor II (FcγRII)-mediated p47(phox) phosphorylation, reactive oxygen species (ROS) production, and TACE activation. CRP also enhanced sLOX-1 release from macrophages derived from peripheral blood mononuclear cells (PBMC) of patients with acute coronary syndrome (ACS). Pretreatment with antibody against FcγRII or with CD32 siRNA, p47(phox) siRNA, apocynin, N-acetylcysteine, tumor necrosis factor-α protease inhibitor 1 (TAPI-1) or TACE siRNA attenuated sLOX-1 release induced by CRP. CRP also elevated serum sLOX-1 levels in a rabbit model of atherosclerosis. Thus, CRP might stimulate sLOX-1 release, and the underlying mechanisms possibly involved FcγRII-mediated p47(phox) phosphorylation, ROS production, and TACE activation.

GENERAL COMMENTARY article Front. Physiol., 18 March 2015Sec. Mitochondrial Research Volume 6 - 2015 | https://doi.org/10.3389/fphys.2015.00083

Polyunsaturated fatty acids (PUFAs) can affect various functions of the immune system including inflammatory responses. An oxidative burst of phagocytes accompanied by reactive oxygen species (ROS) and reactive nitrogen species (RNS) formation is one of the phagocyte functions that could be modulated by PUFAs. To investigate the effects of omega-3 (alpha-linolenic, docosahexaenoic, eicosapentaenoic) and omega-6 (arachidonic, linoleic) PUFAs on lipopolysaccharide (LPS)-stimulated ROS and RNS production by the murine macrophage cell line RAW 264.7. Murine peritoneal macrophages RAW 264.7 were stimulated with LPS (0.1 microg/ml) and treated with 0.1-100 microM omega-3 or omega-6 PUFAs for either 8 (ROS production) or 20 h (RNS production). The cytotoxicity of PUFAs was evaluated by an ATP (adenosine triphosphate) test after both 8 and 20 h of treatment with PUFAs. Changes in ROS production by LPS-treated macrophages subsequently activated with phorbol myristate acetate (PMA) or opsonized zymosan particles (OZP) were determined by luminol-enhanced chemiluminescence, whilst the production of RNS was determined as the concentration of nitrites in cell supernatants (Griess reaction). Changes in inducible nitric oxide synthase (iNOS) expression were evaluated by Western blot analysis. The antioxidant properties of PUFAs were tested by TRAP (total peroxyl radical-trapping antioxidant parameter) assay. All PUFAs in 100 microM concentration except eicosapentaenoic acid decreased ROS production. The effect was most significant when docosahexaenoic acid was used. Arachidonic acid decreased PMA-activated ROS production even in 1 and 10 microM concentrations. On the other hand, 10 and 100 microM eicosapentaenoic acid potentiated ROS production. As concerns RNS production, all the fatty acids that were tested in a concentration of 100 microM decreased iNOS expression and nitrite accumulation. Fatty acids had no significant effect on the viability and proliferation of RAW 264.7 cells. The TRAP assay confirmed that none of the tested PUFAs exerted any significant antioxidant properties. High concentrations of PUFAs of both omega-3 and omega-6 groups can inhibit ROS and RNS formation by stimulated macrophages. The expression of iNOS can also be inhibited. This effect, together with the absence of antioxidant activity and cytotoxic properties, indicates that PUFAs can participate in the regulation of enzymes responsible for reactive species production.

Vascular permeability is a complex process involving the coordinated regulation of multiple signaling pathways in the endothelial cell. It has long been documented that vascular endothelial growth factor (VEGF) greatly enhances microvascular permeability; however, the molecular mechanisms controlling VEGF-induced permeability remain unknown. Treatment of microvascular endothelial cells with VEGF led to an increase in reactive oxygen species (ROS) production. ROS are required for VEGF-induced permeability as treatment with the free radical scavenger, N-acetylcysteine, inhibited this effect. Additionally, treatment with VEGF caused ROS-dependent tyrosine phosphorylation of both vascular-endothelial (VE)-cadherin and beta-catenin. Rac1 was required for the VEGF-induced increase in permeability and adherens junction protein phosphorylation. Knockdown of Rac1 inhibited VEGF-induced ROS production consistent with Rac lying upstream of ROS in this pathway. Collectively, these data suggest that VEGF leads to a Rac-mediated generation of ROS, which, in turn, elevates the tyrosine phosphorylation of VE-cadherin and beta-catenin, ultimately regulating adherens junction integrity.

Albumin-bound fatty acids induce mitochondrial oxidant stress and impair antioxidant responses in proximal tubular cells

This series of debates was initiated for the Journal of Applied Physiology because we believe an important means of searching for truth is through debate where contradictory viewpoints are put forward. This dialectic process whereby a thesis is advanced, then opposed by an antithesis, with a

Cancer treatments in general share various detrimental effects in common, especially upregulation of cardiovascular risk factors. Therefore, the science of onco-cardiology should not be restricted in scope to the side effects of each specific cancer drug. In particular, premature aging induced by cancer treatment may contribute to the chronic health problems of cancer survivors. About 1 660 000 people, including more than 12 000 children below the age of 18 years, are newly diagnosed with a malignancy in the United States every year.1 The American Cancer Society reported that in 2016 there are 15.5 million cancer survivors in the United States (http://www.cancer.org/cancer/news/news/report-number-of-cancer-survivors-continues-to-grow). At present, the 5-year survival rate of patients treated for cancer is 67%. Seventy-five percent of children in whom cancer is diagnosed today will live for at least 10 years; 20% will survive for longer than 35 years.1 Although these numbers are impressive compared with those from decades ago, further improvement of cancer survivors’ life span as well as quality of life and functional status is still necessary. Approximately 75% of cancer survivors have some form of chronic health problem. Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality in this population, particularly after recurrent or second malignancy. The risk of CVD in cancer survivors is 8× higher than that of the general population. The relative risks of coronary artery disease and heart failure in cancer survivors are 10× and 15× higher, respectively, than their siblings without cancer.1 Cancer treatments, including chemotherapy and radiation, can lead to both short- and long-term cardiovascular complications. Evidence of subclinical cardiac and vascular damage was observed in more than 50% of survivors 5 to 10 years after chemotherapy.1 Onco-cardiology is a medical subspecialty concerned with the diagnosis and treatment of CVDs and organ failure mediated by microcirculatory or macrocirculatory …

The iron chelator deferasirox (DFX) prevents complications related to transfusional iron overload in several haematological disorders characterized by marrow failure. It is also able to induce haematological responses in a percentage of treated patients, particularly in those affected by myelodysplastic syndromes. The underlying mechanisms responsible for this feature, however, are still poorly understood. In this study, we investigated the effect of DFX-treatment in human haematopoietic/progenitor stem cells, focussing on its impact on the redox balance, which proved to control the interplay between stemness maintenance, self-renewal and differentiation priming. Here we show, for the first time, that DFX treatment induces a significant diphenyleneiodonium-sensitive reactive oxygen species (ROS) production that leads to the activation of POU5F1 (OCT4), SOX2 and SOX17 gene expression, relevant in reprogramming processes, and the reduction of the haematopoietic regulatory proteins CTNNB1 (β-Catenin) and BMI1. These DFX-mediated events were accompanied by decreased CD34 expression, increased mitochondrial mass and up-regulation of the erythropoietic marker CD71 (TFRC) and were compound-specific, dissimilar to deferoxamine. Our findings would suggest a novel mechanism by which DFX, probably independently on its iron-chelating property but through ROS signalling activation, may influence key factors involved in self-renewal/differentiation of haematopoietic stem cells.

Melatonin as a potential tool against oxidative damage and apoptosis in ejaculated human spermatozoa

Simple SummaryPolymorphonuclear leukocytes (PMN) are the first line and most abundant immune cells against infection. They kill bacteria via phagocytosis, degranulation, and the formation of neutrophil extracellular traps (NETs). The formation of NETs is always accompanied by the production of reactive oxygen species (ROS). We aimed to research the NETs and ROS formation capacity of PMN in different lactational stages of Holstein cows. We also validated a model to mimic infection and inflammation to study the NETs and ROS formation capacity in vitro. Results show that the basal NETs and ROS values of PMN harvested from peripartum and lactating cows were higher than those in nulliparous heifers. The in vitro stimulation, using inflammatory products, of PMN derived from nulliparous heifers increased the production of ROS and NETs. PMN isolated from peripartum and lactating cows are primed to produce NETs and ROS, and this potentially contributes to the cows’ unfavorable inflammatory and immune status at these critical periods in their lactation cycle. The basal NETs and ROS production is lower in nulliparous heifers. Thus, they are an excellent model to mimic and study fundamental aspects of the production of NETs and ROS in vitro.We aimed to research the neutrophil extracellular traps (NETs) and reactive oxygen species (ROS) formation capacity of polymorphonuclear cells (PMN) during different lactational stages of Holstein cows. We also aimed to validate a model which could mimic infection and inflammation in vitro by adding increasing concentrations of lipopolysaccharide (LPS) and phorbol 12-myristate 13-acetate (PMA) to PMN suspensions isolated from nulliparous heifers and evaluate their capacity to produce NETs and ROS. In 3 replicates, we collected blood from nulliparous heifers (n = 3), cows at the end of gestation (n = 3), early postpartum (n = 3) and in mid-lactation (n = 3) in which PMN were isolated. The production of ROS in PMN were assessed using the 2’,7’-Dichlorofluorescein diacetate method, while the SYTOX Orange and Quant-iT™ PicoGreen dsDNA ultra-sensitive nucleic fluorescent acid staining methods were applied in order to quantitatively analyze the formation of NETs. Statistical analyses were performed via linear regression models using the replicate as a random. ROS values of PMN harvested from peripartum cows were 1.3 times increased compared with those in nulliparous heifers (p < 0.01). Compared with nulliparous heifers, the production of NETs by PMN isolated from mid-lactation and postpartum cows was 2.1 and 2.5 times higher (p < 0.01), respectively. In 3 replicates, in vitro stimulation of PMN isolated from nulliparous heifers (n = 3) with LPS linearly increased the production of ROS and NETs (R2 = 0.96 and 0.86, respectively). Similarly, when PMN isolated from nulliparous heifers were stimulated with PMA, a linear increase in the production of ROS (R2 = 0.99) and NETs (R2 = 0.78) was observed. The basal NETs and ROS production is lower in nulliparous heifers. Thus, they are an excellent model to mimic inflammation and study fundamental aspects of the production of NETs and ROS in vitro.

In the present study, the effects of C18 fatty acids with different numbers of double bonds, SA (stearic acid; C18:0), OA (oleic acid; C18:1), LA (linoleic acid; C18:2) and gamma-LNA (gamma-linolenic acid; C18:3), on ROS (reactive oxygen species) production by Jurkat (a human T-lymphocyte-derived cell line) and Raji (a human B-lymphocyte-derived cell line) cells were investigated. ROS production was determined by NBT (Nitro Blue Tetrazolium) reduction (intracellular and extracellular ROS production) and by dihydroethidium oxidation using flow cytometry (intracellular ROS production). The effectiveness on ROS production was gamma-LNA<SA<OA<LA in Jurkat cells and SA<gamma-LNA<OA<LA in Raji cells. LA (found in corn, soya bean and sunflower oils) was more potent than OA (found in olive oil) in stimulating ROS production in both Raji and Jurkat cells. The lower ROS production by OA compared with LA may be one of the benefits of olive oil consumption. As SA and gamma-LNA acids had little or no effect, further studies on the site of ROS production in these cells were carried out with OA and LA only. Activation of NADPH oxidase via PKC (protein kinase C) was found to be the major mechanism of ROS production induced by OA and LA in Jurkat and Raji cells.

Non-ablative pulsed focused ultrasound (pFUS) has shown promise as an immunomodulatory anti-cancer therapeutic. While largely nondestructive to tissues compared ablative ultrasound, pFUS can generate anti-tumor molecular microenvironments and enhance migration of anti-tumor immune cells into B16 and 4T1 flank tumors in immune-competent mice. pFUS also increases the number of dsDNA breaks in nuclear DNA of tumor cells by TUNEL reactions. DNA damage can elicit immune responses by causing cells to express ligands for immune cells and thus may be a critical component of generating observed immune responses in flank tumors following pFUS treatment. Here we investigate potential phyisological mechanisms underlying pFUS-associated DNA damage. B16 melanoma, 4T1 or MBA-MD-231 breast tumors, or C6 glioma cells were cultured and treated with pFUS in vitro (1 MHz, 6 MPa peak negative pressure, 10% duty cycle, 100 pulses). Cells were analyzed for DNA damage by TUNEL, reactive oxygen species (ROS) production by DCFDA, and intracellular Ca2+ by fluo-4. pFUS increased TUNEL reactivity and ROS concentrations in all cell types 2-6 hr after pFUS. Increased TUNEL reactivity was not observed when cells were incubated with the ROS scavenger Trolox (need concentration) following pFUS. pFUS generated Ca2+ transients in all cell types during pFUS treatment. Ca2+ dysregulation can increase cellular ROS production and when cytosolic Ca2+ transients were blocked by BAPTA-AM, both ROS production and TUNEL reactivity was reduced in all cell types. Further investigating mechanisms of Ca2+ transients, application of verapamil (10 uM) during pFUS to inhibit voltage-gated Ca2+ channels (VGCC) also suppressed Ca2+ transients, ROS production, and TUNEL reactivity. Lastly, the magnitudes of Ca2+ transients, ROS production, and TUNEL reactivity induced by pFUS were nonetheless different for different cell types (C6 glioma exhibited the smallest changes after pFUS, while MBA-MD-231 exhibited the largest). This suggested different sensitivities for each cell type to pFUS-induced DNA damage. As Ca2+ homeostasis can be disrupted in tumor cells, we measured resting cytosolic Ca2+ concentrations in each cell type following plasma membrane disruption with digitonin (20 uM). Resting cytosolic Ca2+ concentrations inversely correlated with increased magnitudes of ROS production or TUNEL reactivity following pFUS treatment. In conclusion, pFUS causes DNA damage in tumor cells by initiating cytosolic Ca2+ transients, in part, through VGCC that increase cellular ROS production and lead to dsDNA breaks. The effectiveness of pFUS to stimulate this physiological pathway is related to resting cytosolic Ca2+ concentrations, which different tumor cells could display varying levels of disrupted homeostasis and, thus differing magnitudes of response to pFUS. Future directions will assess potential involvement of mitochondrial dynamics in Ca2+-induced ROS production and in vivo experiments to further understand these dynamics in solid tumor models. Citation Format: Robert B. Rosenblatt, Joseph A. Frank, Scott R. Burks. Pulsed focused ultrasound induces cytosolic calcium transients that increase free radical production and dsDNA breaks in tumor cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3577.