Reactive Oxygen Species In Response Research Articles

SKAP2 is required for defense against K. pneumoniae infection and neutrophil respiratory burst.

Klebsiella pneumoniae is a respiratory, blood, liver, and bladder pathogen of significant clinical concern. We show that the adaptor protein, SKAP2, is required for protection against K. pneumoniae (ATCC 43816) pulmonary infections. Skap2-/- mice had 100-fold higher bacterial burden when compared to wild-type and burden was controlled by SKAP2 expression in innate immune cells. Skap2-/- neutrophils and monocytes were present in infected lungs, and the neutrophils degranulated normally in response to K. pneumoniae infection in mice; however, K. pneumoniae-stimulated reactive oxygen species (ROS) production in vitro was abolished. K. pneumoniae-induced neutrophil ROS response required the activity of SFKs, Syk, Btk, PLCγ2, and PKC. The loss of SKAP2 significantly hindered the K. pneumoniae-induced phosphorylation of SFKs, Syk, and Pyk2 implicating SKAP2 as proximal to their activation in pathogen-signaling pathways. In conclusion, SKAP2-dependent signaling in neutrophils is essential for K. pneumoniae-activated ROS production and for promoting bacterial clearance during infection.

Jasmonic acid, ethylene and ROS are involved in the response of cucumber (Cucumis sativus L.) to aphid infestation

Aphis gossypii Glover (Melon aphid) attack cucumber, and cause great loss of yield and quality. However, the molecular mechanisms of aphid resistance in cucumber remain unclear. Here, we investigated differentially regulated proteins (DRPs) in aphid-infested and non-infested cucumber, using a line (EP6392) that is highly resistant to aphids. Cucumber leaves were subjected to infestation levels of 0, 5 and 20 aphids per cucumber. Fifty-four DRPs were found between the 5 and 0 groups and 109 DRPs were found between the 20 and 0 groups. Sixteen of the up-regulated DRPs and 16 of the down-regulated DRPs were common to both the 5 vs 0 and 20 vs 0 groups. Three genes were up-regulated in both the 5- and 20-aphid-infested plants. These genes encoded 12-oxophytodienoate reductase (OPR), which is involved in jasmonic acid (JA) biosynthesis, 1-aminocyclopropane-1-carboxylic acid oxidase, which is involved in ethylene biosynthesis and peroxidase, which is involved in reactive oxygen species (ROS) formation. Exogenous application of JA decreased the aphid reproduction in cucumber leaves and increased the gene expression level of OPR11. Aphid infestation resulted in rapid increases in the levels of ethylene and ROS. Application of an ethylene receptor inhibitor 1-methylcyclopropene (1-MCP) enhanced aphid reproduction. These results indicate that JA, ethylene and ROS mediate the interaction between aphids and cucumber. The early response of ROS and ethylene might be signaling to regulate the cucumber response to aphid infestation, and JA and ethylene might enhance the aphid resistance in cucumber.

Iminoboronate Backbone‐Based Hyperbranched Polymeric Micelles with Fenton‐Like Enhanced ROS Response

AbstractCompared to normal cells, there is a relatively high level of reactive oxygen species (ROS) in tumor cells caused by defecting ROS scavenging systems. To this issue, developing ROS‐responsive nanocarriers has been a promising way to cancer therapy. However, it is always difficult for a certain ROS‐responsive nanocarrier to be perfectly triggered due to the complexity of cancerous tissues. Thus, it is pressing to improve the response sensitivity of ROS‐responsive nanocarriers. Herein, the Fenton‐like reaction enhanced ROS response of polymeric nanocarriers of an iminoboronate backbone‐based hyperbranched polymer with metallisable 8‐hyroxyquinoline (HQ) moieties is demonstrated. HQ‐Cu catalytic sites can be formed at the prepared nanocarriers via the complexation of Cu(II) ions and HQ moieties. Upon H2O2, hydroxyl radicals (·OH) are quickly generated via the Fenton‐like reaction between H2O2 and HQ‐Cu. Then, the oxidative cleavage of iminoboronate moieties can be effectively activated to disrupt the nanocarriers, leading to a rapid release of encapsulated drugs. It is proposed that this kind of polymeric nanocarriers with Cu‐complexed catalyzing‐triggered ROS response may achieve highly effective oxidation therapy.

Examination of the demyelination process in mGFAP‐driven conditional transient receptor potential ankyrin 1 (TRPA1) receptor knockout mice

Transient receptor potential ankyrin 1 (TRPA1) receptors are non‐selective cation channels responsive to a variety of exogenous irritants and endogenous stimuli including products of oxidative stress. It is mainly expressed by primary sensory neurons however, expression of TRPA1 by astrocytes and oligodendrocytes has recently been detected in the mouse brain. Genetic deletion of TRPA1 was shown to attenuate cuprizone‐induced oligodendrocyte apoptosis and myelin loss in mice. In the present study we investigated the astrocyte‐specific mGFAP‐driven conditional TRPA1 gene deficient mice in the cuprizone model. Astrocyte‐specific knockout animals were generated by crossbreeding GFAP‐Cre+/− and floxed TRPA1 (TRPA1Fl/Fl) mice. Cuprizone was administered during 6 weeks and demyelination was followed by magnetic resonance imaging (MRI). At the end of the treatment, myelin loss and glial activation were also investigated by histological methods. The results of the MRI showed significantly increased signal intensity in cuprizone‐treated GFAP‐Cre−/− TRPA1Fl/Fl mice compared to GFAP‐Cre+/− TRPA1Fl/− and GFAP‐Cre+/− TRPA1Fl/Fl animals on week 3 and week 4. However, by week 6 of the treatment the difference was not detectable by either the MRI or the histological methods. According to the currently available data, we presume that TRPA1 receptors localized on astrocytes can be activated by reactive oxygen species in response to cuprizone challenge and the consequent release of pro‐inflammatory mediators contributes to the progression of oligodendrocyte apoptosis. However, the global TRPA1 KO mice presented a more attenuated demyelination compared to the conditional KO mice, it could be hypothesized that TRPA1 receptors expressed by other cell types (neurons, oligodendrocytes) in the brain may also participate in the demyelination process.Support or Funding InformationThis research was funded by grants “The role of neuro‐inflammation in neurodegeneration: from molecules to clinics” (EFOP‐3.6.2‐16‐2017‐00008); Hungarian Brain Research Program 2. 2017‐1.2.1‐NKP‐2017‐00002. and the University of Pécs is acknowledged for a support by the 17886‐4/23018/FEKUTSTRAT excellence grant. G.K. was supported by Richter Gedeon Centenárium Foundation.

Progesterone induced blocking factor improves blood pressure, mitochondrial dysfunction and reactive oxygen species in response to sFlt‐1 induced hypertension during pregnancy

Preeclampsia (PE) is characterized by new onset hypertension in association with placental ischemia, reduced fetal weight, elevated soluble fms‐like tyrosine kinase‐1 (sFlt‐1) and placental mitochondrial (mt) dysfunction and oxidative stress (ROS). Infusion of sFlt‐1 causes hypertension and endothelial and renal dysfunction in pregnant rodent models of PE. However a role for sFlt‐1 in causing mt dysfunction and ROS is unknown. Progesterone induced blocking factor (PIBF), is a product of progesterone signaling in early pregnant which controls pro‐inflammatory processes and thus markers of endothelial dysfunction. We have previously shown that progesterone supplementation improves markers of endothelial dysfunction in the RUPP rat. Moreover, we have more recently shown that PIBF lowers blood pressure in the RUPP rat model of PE. This study was designed to test two hypothesis. We first wanted to determine a role for sFlt‐1 to cause mt dysfunction and ROS during pregnancy. We next hypothesized the PIBF supplementation would lower in sFlt‐1 induced hypertension during pregnancy and improve mt function in response to sFlt‐1 during pregnancy. sFlt‐1 was infused into normal pregnant (NP) Sprague‐Dawley rats (3.7 μg·kg−1·day−1 for 6 days, gestation days 13–19) in the presence or absence of PIBF (2.0 μg/mL) administered intraperitoneal on GD 15 to normal pregnant (NP) rats. Mean arterial blood pressure (MAP) and placental mt ROS were measured on GD 19. Infusion of sFlt‐1 into NP rats increased MAP 112 ±2 (n=11) compared with control NP rats 98±2 mmHg (n=15, p<0.05). Administration of PIBF reduced MAP to 100±1 mmHg in the presence of sFlt‐1 (n=5, p<0.05). Mt ROS in placenta was 108±6 in NP (n=4), 429±32 in NP+ sFlt‐1 (n=3, p<0.05), and significantly reduced to 234±15 in NP+ sFlt‐1+ PIBF (n=3, p<0.05). State 3 respiration, which is indicative of ATP production, was reduced in placentas of sFlt‐1 infused rats versus NP, but was improved with PIBF. Overall, our study implicates a role for sFlt‐1 to reduce placental mt function during pregnancy and that supplementation of PIBF improved placental mt function which was associated with improved blood pressures. Our data indicate the importance of improved progesterone signaling to restore placental function in the presence of sFlt‐1 which led to improved hypertension and therefore should be considered a potential therapeutic for PE.Support or Funding InformationNIH Grants: RO1HD067541‐06 and P20GM121334; T32HL105324

Hesperetin attenuated acetaminophen-induced hepatotoxicity by inhibiting hepatocyte necrosis and apoptosis, oxidative stress and inflammatory response via upregulation of heme oxygenase-1 expression

Acetaminophen (APAP) is a common antipyretic and analgesic drug, but its overdose can induce acute liver failure with lack of effective therapies. Hesperetin, a dihydrogen flavonoid compound, has been revealed to exert multiple pharmacological activities. Here, we explored the protective effects and mechanism of hesperetin on APAP-induced hepatotoxicity. The results showed that pretreatment with hesperetin dose-dependently attenuated APAP-induced acute liver injury in mice, as measured by alleviated serum enzymes activities, hepatic pathological damage and apoptosis. Moreover, hesperetin mitigated APAP-induced oxidative stress and inflammatory response in mice by inhibiting oxidative molecules but increasing antioxidative molecules production, reducing inflammatory cells infiltration and proinflammatory cytokines production, blocking Toll-like receptor (TLR)-4 signal activation. In vitro experiment indicated that hesperetin dose-dependently inhibited APAP-primed cytotoxicity, apoptosis, and reactive oxygen species (ROS) in murine AML12 hepatocytes. Notably, hesperetin up-regulated expression of heme oxygenase-1 (HO-1) mRNA and protein in the liver of mice and AML12 cells exposed to APAP. Furthermore, knockdown of HO-1 by adenovirus-mediated HO-1 siRNA reverted these beneficial effects of hesperetin on APAP-induced hepatocytotoxicity as well as ROS and inflammatory response in vivo and in vitro. These findings demonstrated that hesperetin exerted a protective prophylaxis on APAP-induced acute liver injury by inhibiting hepatocyte necrosis and apoptosis, oxidative stress and inflammatory response via up-regulating HO-1 expression.

BALANCE OF GLUTATHIONE-RELATED PROCESSES IN ALVEOLAR MACROPHAGES UNDER EXPOSURE TO SUSPENDED PARTICULATE MATTER OF ATMOSPHERIC AIR IN OF WISTAR RATS

Introduction. Air suspended particulate matter (SPM) directly influence on the human respiratory system. Dispersion is one of the characteristics of SPM determining their pathogenicity. Alveolar macrophages (AMs) produce reactive oxygen species in response to an exposure that may lead to oxidative stress. The aim of the study. To assess the contribution of the glutathione antioxidant system to the protection of AMs from oxidative stress induced by air SPMs in Vladivostok’s districts with various man-made loads. Material and methods. AMs were isolated from bronchoalveolar lavage of 17 Wistar rats. AMs were exposed by model suspensions (MS) for 2 days. MSs were identical air composition of Vladivostok’s districts with insignificant (MS № 1) and high (MS № 2) technogenic load. MS № 1 contained 22% of particles with a diameter of less than 10 µm. MS № 2 contained 70% of particles with a diameter smaller than 10 μm. The levels of malondialdehyde, glutathione and total antioxidant activity in cell culture and culture fluid were determined. Results. The gain in the proportion of fine and ultrafine particles in MS № 2 has been established to lead to an increase in lipid peroxidation in AMs and a compensatory elevation in the antioxidant activity. The elevation of oxidized glutathione concentration in cell culture indicates the intensification of hydroperoxide detoxification by AMs. The reduction of reduced glutathione exocytosis supports intracellular antioxidant processes. Conclusion. An increase in the fraction of fine and ultrafine particles in the air appears to shift AM redox balance towards oxidative stress, contributing to the formation and the progression of pathological disorders.

Mitochondria at the crossroads of ATM-mediated stress signaling and regulation of reactive oxygen species

The Ataxia-telangiectasia mutated (ATM) kinase responds to DNA double-strand breaks and other forms of cellular stress, including reactive oxygen species (ROS). Recent work in the field has uncovered links between mitochondrial ROS and ATM activation, suggesting that ATM acts as a sensor for mitochondrial derived ROS and regulates ROS accumulation in cells through this pathway. In addition, characterization of cells from Ataxia-telangiectasia patients as well as ATM-deficient mice and cell models suggest a role for ATM in modulating mitochondrial gene expression and function. Here we review ROS responses related to ATM function, recent evidence for ATM roles in mitochondrial maintenance and turnover, and the relationship between ATM and regulation of protein homeostasis.

Biochemical and genotoxic biomarkers and cell cycle assessment in the zebrafish liver (ZF-L) cell line exposed to the novel metal-insecticide magnesium-hespiridin complex

The flavonoid metal-insecticide magnesium-hesperidin complex (MgHP) has recently been considered as a novel insecticide to replace some persistent pesticides. However, it is important to evaluate its action on non-target species, mainly those living in an aquatic environment, as these ecosystems are the final receptors of most chemicals. Reactive oxygen species, antioxidant and oxidative stress biomarkers, genotoxicity as well as cell cycle was evaluated in the liver cell line from zebrafish (Danio rerio; ZF-L) exposed to 0, 0.1, 1, 10, 100 and 1000 ng mL−1 MgHP. MgHP affected cell stability by increasing reactive oxygen species (ROS) in both exposure times (24 and 96 h) at high concentrations. Catalase (CAT) activity decreased after 24 h exposure, and glutathione and metallothionein values increased, avoiding the lipid peroxidation. Genotoxicity increased as MgHP concentration increased, after 24 h exposure, exhibiting nuclear abnormalities; it was recovered after 96 h exposure, evidencing possible stimulation of DNA repair mechanisms. The alteration in the cell cycle (increasing in the Sub-G1 phase and decreasing in the S-phase) was associated with chromosomal instability. In conclusion, the responses of ROS and the antioxidant defense system depended on MgHP concentration and time exposure, while DNA exhibited some instability after 24 h exposure, which was recovered after 96 h.

TRPV4-A Missing Link Between Mechanosensation and Immunity.

Transient receptor potential vanilloid-type 4 (TRPV4) cation channel is widely expressed in all tissues as well as in immune cells and its function as mechanosensitive Ca2+ channel seems to be conserved throughout all mammalian species. Of late, emerging evidence has implicated TRPV4 in the activation and differentiation of innate immune cells, especially in neutrophils, monocytes, and macrophages. As such, TRPV4 has been shown to mediate neutrophil adhesion and chemotaxis, as well as production of reactive oxygen species in response to pro-inflammatory stimuli. In macrophages, TRPV4 mediates formation of both reactive oxygen and nitrogen species, and regulates phagocytosis, thus facilitating bacterial clearance and resolution of infection. Importantly, TRPV4 may present a missing link between mechanical forces and immune responses. This connection has been exemplary highlighted by the demonstrated role of TRPV4 in macrophage activation and subsequent induction of lung injury following mechanical overventilation. Mechanosensation via TRPV4 is also expected to activate innate immune cells and establish a pro-inflammatory loop in fibrotic diseases with increased deposition of extracellular matrix (ECM) and substrate stiffness. Likewise, TRPV4 may be activated by cell migration through the endothelium or the extracellular matrix, or even by circulating immune cells squeezing through the narrow passages of the pulmonary or systemic capillary bed, a process that has recently been linked to neutrophil priming and depriming. Here, we provide an overview over the emerging role of TRPV4 in innate immune responses and highlight two distinct modes for the activation of TRPV4 by either mechanical forces (“mechanoTRPV4”) or by pathogens (“immunoTRPV4”).

Comparison of in vitro toxicity of aerosolized engineered nanomaterials using air-liquid interface mono-culture and co-culture models

Airborne engineered nanomaterials (ENMs) can readily enter the human body through inhalation potentially leading to adverse health effects such as cardiovascular and pulmonary diseases. Our group has previously utilized and validated an integrated low flow system capable of generating and depositing airborne ENMs directly onto cells at an air-liquid interface (ALI). To further improve this ALI method for an even closer representation of the in vivo system, a co-culture model containing epithelial, endothelial and macrophage cell lines (A549, EA.hy 926, and THP-1 differentiated macrophages) was established and validated for testing ENMs toxicity. In the co-culture model, cells were exposed to citrate-capped gold (Au), 15% silver on silica (Ag-SiO2) and copper oxide (CuO) ENMs under the same protocol (4 h ALI exposure with a target concentration of 3.5 mg/m3) and compared to responses with A549 cells only or THP-1 differentiated cells only. The toxicological profile was assessed by measuring cell viability, reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) release, and interleukin (IL)-8 concentration. Results showed that 15% Ag-SiO2 induced more oxidative stress-related toxicity in the co-culture than in A549 cells alone. Both 15% Ag-SiO2 and CuO exposure produced significantly higher levels of IL-8 in the co-culture compared with A549 cells alone. Citrate-capped Au was largely inert. Further exposures of CuO on macrophages alone provided evidence of cell-cell interaction in the co-culture model. In addition, the co-culture model exhibited a similar response to primary human bronchial epithelial cells in terms of ROS and IL-8 responses after CuO exposure, suggesting a more advanced refinement of the conventional model for in vitro inhalation study.

Redox metabolism: the hidden player in carbon and nitrogen signaling?

While decades of research have considered redox metabolism as purely defensive, recent results show that reactive oxygen species (ROS) are necessary for growth and development. Close relationships have been found between the regulation of nitrogen metabolism and ROS in response to both carbon and nitrogen availability. Root nitrate uptake and nitrogen metabolism have been shown to be regulated by a signal from the oxidative pentose phosphate pathway (OPPP) in response to carbon signaling. As a major source of NADP(H), the OPPP is critical to maintaining redox balance under stress situations. Furthermore, recent results suggest that at least part of the regulation of the root nitrate transporter by nitrogen signaling is also linked to the redox status of the plant. This leads to the question of whether there is a more general role of redox metabolism in the regulation of nitrogen metabolism by carbon and nitrogen. This review highlights the role of the OPPP in carbon signaling and redox metabolism, and the interaction between redox and nitrogen metabolism. We discuss how redox metabolism could be an important player in the regulation of nitrogen metabolism in response to carbon/nitrogen interaction and the implications for plant adaptation to extreme environments and future crop development.

TRPM2-mediated extracellular Ca2+ entry promotes acinar cell necrosis in biliary acute pancreatitis.

Acute biliary pancreatitis is a significant clinical challenge as currently no specific pharmaceutical treatment exists. Intracellular Ca2+ overload, increased reactive oxygen species (ROS) production, mitochondrial damage and intra-acinar digestive enzyme activation caused by bile acids are hallmarks of acute biliary pancreatitis. Transient receptor potential melastatin 2 (TRPM2) is a non-selective cation channel that has recently emerged as an important contributor to oxidative-stress-induced cellular Ca2+ overload across different diseases. We demonstrated that TRPM2 is expressed in the plasma membrane of mouse pancreatic acinar and ductal cells, which can be activated by increased oxidative stress induced by H2 O2 treatment and contributed to bile acid-induced extracellular Ca2+ influx in acinar cells, which promoted acinar cell necrosis in vitro and in vivo. These results suggest that the inhibition of TRPM2 may be a potential treatment option for biliary pancreatitis. Acute biliary pancreatitis poses a significant clinical challenge as currently no specific pharmaceutical treatment exists. Disturbed intracellular Ca2+ signalling caused by bile acids is a hallmark of the disease, which induces increased reactive oxygen species (ROS) production, mitochondrial damage, intra-acinar digestive enzyme activation and cell death. Because of this mechanism of action, prevention of toxic cellular Ca2+ overload is a promising therapeutic target. Transient receptor potential melastatin 2 (TRPM2) is a non-selective cation channel that has recently emerged as an important contributor to oxidative-stress-induced cellular Ca2+ overload across different diseases. However, the expression and possible functions of TRPM2 in the exocrine pancreas remain unknown. Here we found that TRPM2 is expressed in the plasma membrane of mouse pancreatic acinar and ductal cells, which can be activated by increased oxidative stress induced by H2 O2 treatment. TRPM2 activity was found to contribute to bile acid-induced extracellular Ca2+ influx in acinar cells, but did not have the same effect in ductal cells. The generation of intracellular ROS in response to bile acids was remarkably higher in pancreatic acinar cells compared to isolated ducts, which can explain the difference between acinar and ductal cells. This activity promoted acinar cell necrosis in vitro independently from mitochondrial damage or mitochondrial fragmentation. In addition, bile-acid-induced experimental pancreatitis was less severe in TRPM2 knockout mice, whereas the lack of TRPM2 had no protective effect in cerulein-induced acute pancreatitis. Our results suggest that the inhibition of TRPM2 may be a potential treatment option for biliary pancreatitis.

Efficacy-shaping nanomedicine by loading Calcium Peroxide into Tumor Microenvironment-responsive Nanoparticles for the Antitumor Therapy of Prostate Cancer.

Rationale: Prostate cancer has become one of the most threatening malignant tumors in men, leading to an imperative need to develop effective and safe therapies. Because of the unique metabolism of tumor cells, the tumor microenvironment (TME) exhibits distinctive properties compared with normal tissues, among which the pH difference has been utilized as an ideal antitumor strategy. Herein, we introduce a reactive oxygen species (ROS)-controlled-release nanosystem with TME-responsiveness by applying hollow mesoporous silica nanoparticles (HMSNs) as carriers loaded with calcium peroxide (CaO2) and coated with polyacrylic acid (PAA) to construct the functional material CaO2@HMSNs-PAA. The differences in pH values and exogenous ROS scavenging abilities between the tumor tissue and normal tissues and the dual pH-responsiveness from CaO2 and PAA lay a scientific foundation for the application of CaO2@HMSNs-PAA in the tumor-selective therapy for prostate cancer.Methods: The morphology and the structure of the nanosystem were characterized by the transmission electron microscope, scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, zeta potential, dynamic light scattering measurement, low-angle X-ray diffraction patterns and nitrogen adsorption/desorption isotherm. The CaO2 loading capacity and release profiles in different buffer solutions were determined by inductively coupled plasma-mass spectrometry. The in vitro intracellular uptake of CaO2@HMSNs-PAA was explored on the PC-3 prostate cancer cell line via confocal laser scanning microscopy. The CCK-8 cell proliferation assay was conducted to evaluate the cytotoxicity of CaO2@HMSNs-PAA against PC-3 cells. ROS produced by CaO2@HMSNs-PAA was observed by a fluorescence microscope. The flow cytometry was utilized to analyze the apoptosis of PC-3 cells induced by CaO2@HMSNs-PAA. The Western blot analysis was performed to detect expressions of critical mitochondria-mediated apoptosis markers in PC-3 cells after incubation with CaO2@HMSNs-PAA. The in vivo biosafety and antitumor efficacy were evaluated out on BALB/c mice and BALB/c nude mice subcutaneously transplanted with PC-3 cells, respectively.Results: Comprehensive characterizations indicated the successful synthesis of CaO2@HMSNs-PAA with significant TME-responsiveness. The experimental results demonstrated that the well-developed nanocarrier could efficiently deliver CaO2 to the tumor site and release ROS in response to the decreased pH value of TME, exerting ideal antitumor effects both in vitro and in vivo by activating the mitochondria-mediated apoptosis pathway. Simultaneously, this nanoplatform caused no detectable damage to normal tissues.Conclusions: After loading into the above nanocomposite, the free CaO2 without a significant antitumor effect can exert excellent antitumor efficacy by responsively releasing ROS under the acidic TME to induce the mitochondria-mediated apoptosis via remarkable oxidative stress and simultaneously minimize damages to normal tissues. The current study presents a new concept of “efficacy-shaping nanomedicine” for the tumor-selective treatment of prostate cancer.

Therapeutic iminoboronate-based polymersomes with a Cu(ii)-mediated Fenton reaction-enhanced ROS-response.

Reactive oxygen species (ROS)-responsive prodrug nanoplatforms may not work efficiently due to insufficient ROS concentrations, so therapeutic polymersomes of a metallisable triamine-centered iminoboronate-functionalized amphiphilic starlike prodrug (N3-(OEG-IBCAPE)4) are prepared to show a Cu(ii)-mediated Fenton reaction-enhanced ROS response.

Organochlorine pesticides induce inflammation, ROS production, and DNA damage in human epithelial ovary cells: An invitro study.

Although the etiology of ovarian cancer is not clear, certain factors are implicated in this disease, such as ovulation, gonadotropic and steroid hormones, growth factors, cytokines, environmental agents, etc. Epidemiological studies have proven environmental exposure to pesticides with an increased risk of Epithelial Ovarian Cancer (EOC); however, the molecular mechanism underlying the carcinogenic effects of pesticides in human ovary remains poorly understood. The present study aimed to study the pro-inflammatory response of organochlorine pesticides (OCPs) namely β-hexachlorocyclohexane (β-HCH), dichlorodiphenyldichloroethylene (DDE) and Dieldrin following exposure to human ovary surface epithelial cells (HOSE) for risk prediction of epithelial ovarian cancer. We found high level of Reactive oxygen species (ROS) production and DNA damage along with up-regulation of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, nuclear factor kappa B (NF-kB) and cyclooxygenase (COX)-2 expression in OCPs treated HOSE cells compared to control (DMSO). The result of the present study suggests that β-HCH, DDE, and Dieldrin exposure induce ROS and pro-inflammatory response as well as DNA damage in HOSE cells. These various results show that OCPs may account for the neoplastic transformation of HOSE cells in the ovary.

Bioactivation of Napabucasin Triggers Reactive Oxygen Species-Mediated Cancer Cell Death.

Napabucasin (2-acetylfuro-1,4-naphthoquinone or BBI-608) is a small molecule currently being clinically evaluated in various cancer types. It has mostly been recognized for its ability to inhibit STAT3 signaling. However, based on its chemical structure, we hypothesized that napabucasin is a substrate for intracellular oxidoreductases and therefore may exert its anticancer effect through redox cycling, resulting in reactive oxygen species (ROS) production and cell death. Binding of napabucasin to NAD(P)H:quinone oxidoreductase-1 (NQO1), and other oxidoreductases, was measured. Pancreatic cancer cell lines were treated with napabucasin, and cell survival, ROS generation, DNA damage, transcriptomic changes, and alterations in STAT3 activation were assayed in vitro and in vivo. Genetic knockout or pharmacologic inhibition with dicoumarol was used to evaluate the dependency on NQO1. Napabucasin was found to bind with high affinity to NQO1 and to a lesser degree to cytochrome P450 oxidoreductase (POR). Treatment resulted in marked induction of ROS and DNA damage with an NQO1- and ROS-dependent decrease in STAT3 phosphorylation. Differential cytotoxic effects were observed, where NQO1-expressing cells generating cytotoxic levels of ROS at low napabucasin concentrations were more sensitive. Cells with low or no baseline NQO1 expression also produced ROS in response to napabucasin, albeit to a lesser extent, through the one-electron reductase POR. Napabucasin is bioactivated by NQO1, and to a lesser degree by POR, resulting in futile redox cycling and ROS generation. The increased ROS levels result in DNA damage and multiple intracellular changes, one of which is a reduction in STAT3 phosphorylation.

Reactive oxygen species (ROS) generation is stimulated by κ opioid receptor activation through phosphorylated c-Jun N-terminal kinase and inhibited by p38 mitogen-activated protein kinase (MAPK) activation

Activation of the mitogen-activated protein kinase (MAPK) c-Jun N-terminal kinase (JNK) by the Gi/o protein-coupled κ opioid receptor (KOR), μ opioid, and D2 dopamine receptors stimulates peroxiredoxin 6 (PRDX6)-mediated production of reactive oxygen species (ROS). ROS production by KOR-inactivating antagonists norbinaltorphimine (norBNI) and JDTic blocks Gαi protein activation, but the signaling mechanisms and consequences of JNK activation by KOR agonists remain uncharacterized. Binding of arrestins to KOR causes desensitization of G protein signaling and acts as a scaffold to initiate MAPK activation. Here, we found that the KOR agonists U50,488 and dynorphin B stimulated biphasic JNK activation with an early arrestin-independent phase, requiring the small G protein RAC family small GTPase 1 (RAC1) and protein kinase C (PKC), and a later arrestin-scaffolded phase, requiring RAC1 and Ras homolog family member (RHO) kinase. JNK activation by U50,488 and dynorphin B also stimulated PRDX6-dependent ROS production but with an inverted U-shaped dose-response relationship. KOR agonist-induced ROS generation resulted from the early arrestin-independent phase of JNK activation, and this ROS response was suppressed by arrestin-dependent activation of the MAPK p38. The apparent balance between p38 MAPK and JNK/ROS signaling has important physiological implications for understanding of dynorphin activities during the stress response. To visualize these activities, we monitored KOR agonist-mediated activation of ROS in transfected live cells by two fluorescent sensors, CellROX Green and HyPerRed. These findings establish an important aspect of opioid receptor signaling and suggest that ROS induction may be part of the physiological response to KOR activation.

Targeting Myeloperoxidase Disrupts Mitochondrial Redox Balance and Overcomes Cytarabine Resistance in Human Acute Myeloid Leukemia.

Chemotherapies alter cellular redox balance and reactive oxygen species (ROS) content. Recent studies have reported that chemoresistant cells have an increased oxidative state in hematologic malignancies. In this study, we demonstrated that chemoresistant acute myeloid leukemia (AML) cells had a lower level of mitochondrial and cytosolic ROS in response to cytarabine (AraC) and overexpressed myeloperoxidase (MPO), a heme protein that converts hydrogen peroxide to hypochlorous acid (HOCl), compared with sensitive AML cells. High MPO-expressing AML cells were less sensitive to AraC in vitro and in vivo. They also produced higher levels of HOCl and exhibited an increased rate of mitochondrial oxygen consumption when compared with low MPO-expressing AML cells. Targeting MPO expression or enzyme activity sensitized AML cells to AraC treatment by triggering oxidative damage and sustaining oxidative stress, particularly in high MPO-expressing AML cells. This sensitization stemmed from mitochondrial superoxide accumulation, which impaired oxidative phosphorylation and cellular energetic balance, driving apoptotic death and selective eradication of chemoresistant AML cells in vitro and in vivo. Altogether, this study uncovers a noncanonical function of MPO enzyme in maintaining redox balance and mitochondrial energetic metabolism, therefore affecting downstream pathways involved in AML chemoresistance. SIGNIFICANCE: These findings demonstrate the role of myeloperoxidase in the regulation of ROS levels and sensitivity of AML cells to cytarabine, an essential chemotherapeutic backbone in the therapy of AML.

Genotoxicity and DNA damage signaling in response to complex mixtures of PAHs in biomass burning particulate matter from cashew nut roasting

Approximately 3 billion people world-wide are exposed to air pollution from biomass burning. Herein, particulate matter (PM) emitted from artisanal cashew nut roasting, an important economic activity worldwide, was investigated. This study focused on: i) chemical characterization of polycyclic aromatic hydrocarbons (PAHs) and oxygenated (oxy-) PAHs; ii) intracellular levels of reactive oxygen species (ROS); iii) genotoxic effects and time- and dose-dependent activation of DNA damage signaling, and iv) differential expression of genes involved in xenobiotic metabolism, inflammation, cell cycle arrest and DNA repair, using A549 lung cells. Among the PAHs, chrysene, benzo[a]pyrene (B[a]P), benzo[b]fluoranthene, and benz[a]anthracene showed the highest concentrations (7.8–10 ng/m3), while benzanthrone and 9,10-anthraquinone were the most abundant oxy-PAHs. Testing of PM extracts was based on B[a]P equivalent doses (B[a]Peq). IC50 values for viability were 5.7 and 3.0 nM B[a]Peq at 24 h and 48 h, respectively. At these low doses, we observed a time- and dose-dependent increase in intracellular levels of ROS, genotoxicity (DNA strand breaks) and DNA damage signaling (phosphorylation of the protein checkpoint kinase 1 – Chk1). In comparison, effects of B[a]P alone was observed at micromolar range. To our knowledge, no previous study has demonstrated an activation of pChk1, a biomarker used to estimate the carcinogenic potency of PAHs in vitro, in lung cells exposed to cashew nut roasting extracts. Sustained induction of expression of several important stress response mediators of xenobiotic metabolism (CYP1A1, CYP1B1), ROS and pro-inflammatory response (IL-8, TNF-α, IL-2, COX2), and DNA damage response (CDKN1A and DDB2) was also identified. In conclusion, our data show high potency of cashew nut roasting PM to induce cellular stress including genotoxicity, and more potently when compared to B[a]P alone. Our study provides new data that will help elucidate the toxic effects of low-levels of PAH mixtures from air PM generated by cashew nut roasting.