Effects Of H2O2 Treatment Research Articles

Andrographolide‐Mediated Protection of Barrier Integrity and Permeability is Mediated Through NLRP3 Inflammasome Inhibition in Blood‐Brain Barrier Endothelial Cells

The blood‐brain barrier (BBB) that consists of the inter‐endothelial tight junctions, acts as the major blood‐brain interface and regulator of brain microvascular hyperpermeability. In the brain, the loss of BBB integrity and hyperpermeability leads to cerebral edema formation and intracranial pressure elevation in traumatic brain injury and ischemic strokes. Recent studies demonstrated that reactive oxygen species are potential signals for the NLR family pyrin domain containing 3 (NLRP3) inflammasome activation that leads to interleukin‐1β (IL‐1β) secretion. IL‐1β plays a major role in promoting BBB hyperpermeability in various brain pathologies, including TBI. Furthermore, recent studies from our lab have demonstrated a tri‐phasic role for hydrogen peroxide (H2O2) in BBB endothelial cells where it promotes, angiogenesis, hyperpermeability and apoptosis in a tri‐phasic and concentration dependent manner. Hydrogen peroxide plays a major role physiologically as the second messenger and pathologically as an inducer of oxidative stress and associated cellular signaling. We hypothesized that in BBB endothelial cells, H2O2‐induced barrier dysfunction and hyperpermeability are NLRP3 inflammasome‐dependent. The main objective of our study was to evaluate the role of NLRP3 inflammasome signaling in H2O2‐mediated barrier dysfunction and hyperpermeability in human brain microvascular endothelial cells and to test whether andrographolide, a labdane diterpenoid possessing potent anti‐inflammatory properties will attenuate such effects. Th effect of H2O2 treatment on tight junction integrity/permeability was studied using zonula occludens‐1 (ZO‐1) immunofluorescence localization, ZO‐1 immunoblot analysis, Transwell monolayer permeability assay using FITC‐dextran (10‐kDa) as a fluorescent marker and cell viability/apoptosis assay. The effect of NLRP3 inhibitor (MCC950) and andrographolide on H2O2‐induced hyperpermeability was studied using Transwell permeability assay. Our results show that, CRISPR/Cas‐9‐mediated knockdown of ZO‐1 resulted in monolayer hyperpermeability demonstrating the significance of ZO‐1 in regulating barrier functions. CRISPR‐based activation of NLRP3 induced monolayer hyperpermeability whereas CRISPR/Cas‐9‐based NLRP3 knockdown had no significant effect on permeability. H2O2 (10µM) induced monolayer hyperpermeability and the effect was decreased by MCC950 and andrographolide treatment. Hydrogen peroxide induced cathepsin B (an activator of the NLRP3 pathway) activity significantly, and the effect was decreased by andrographolide treatment. H2O2‐mediated barrier dysfunction and hyperpermeability were not due to changes in cell viability/apoptosis. These results suggest that NLRP3 is a mediator of H2O2‐induced barrier dysfunction and hyperpermeability in human BBB endothelial cells and andrographolide is an effective inhibitor of this pathway.

Effects of H2O2 Treatment Combined With PI3K Inhibitor and MEK Inhibitor in AGS Cells: Oxidative Stress Outcomes in a Model of Gastric Cancer.

Gastric cancer is worldwide the fifth and third cancer for incidence and mortality, respectively. Stomach wall is daily exposed to oxidative stress and BER system has a key role in the defense from oxidation-induced DNA damage, whilst ErbB receptors have important roles in the pathogenesis of cancer. We used AGS cells as an aggressive gastric carcinoma cell model, treated with H2O2 alone or combined with ErbB signaling pathway inhibitors, to evaluate the effects of oxidative stress in gastric cancer, focusing on the modulation of ErbB signaling pathways and their eventual cross-talk with BER system. We showed that treatment with H2O2 combined with PI3K/AKT and MEK inhibitors influenced cell morphology and resulted in a reduction of cancer cell viability. Migration ability was reduced after H2O2 treatment alone or combined with MEK inhibitor and after PI3K/AKT inhibitor alone. Western blotting analysis showed that oxidative stress stimulated EGFR pathway favoring the MAPKs activation at the expense of PI3K/AKT pathway. Gene expression analysis by RT-qPCR showed ErbB2 and OGG1 increase under oxidative stress conditions. Therefore, we suggest that in AGS cells a pro-oxidant treatment can reduce gastric cancer cell growth and migration via a different modulation of PI3K and MAPKs pathways. Moreover, the observed ErbB2 and OGG1 induction is a cellular response to protect the cells from H2O2-induced cell death. In conclusion, to tailor specific combinations of therapies and to decide which strategy to use, administration of a chemotherapy that increases intracellular ROS to toxic levels, might not only be dependent on the tumor type, but also on the molecular targeting therapy used.

Effect of H2o2 Treatment on Flavor Quality, Texture Quality and ROS Metabolism in ‘Hongshi’ Kiwifruit Fruit During Ambient Storage

Effect of H2o2 Treatment on Flavor Quality, Texture Quality and ROS Metabolism in ‘Hongshi’ Kiwifruit Fruit During Ambient Storage

PER2 Regulates Reactive Oxygen Species Production in the Circadian Susceptibility to Ischemia/Reperfusion Injury in the Heart.

The main objective of this study was to investigate the diurnal differences in Period 2 (PER2) expression in myocardial ischemia-reperfusion (I/R) injury. We investigated diurnal variations in oxidative stress and energy metabolism after myocardial I/R in vitro and in vivo. In addition, we also analyzed the effects of H2O2 treatment and serum shock in H9c2 cells transfected with silencing RNA against Per2 (siRNA-Per2) in vitro. We used C57BL/6 male mice to construct a model of I/R injury at zeitgeber time (ZT) 2 and ZT14 by synchronizing the circadian rhythms. Our in vivo analysis demonstrated that there were diurnal differences in the severity of injury caused by myocardial infarctions, with more injury occurring in the daytime. PER2 was significantly reduced in heart tissue in the daytime and was higher at night. Our results also showed that more severe injury of mitochondrial function in daytime produced more reactive oxygen species (ROS) and less ATP, which increased myocardial injury. In vitro, our findings presented a similar trend showing that apoptosis of H9c2 cells was increased when PER2 expression was lower. Meanwhile, downregulation of PER2 disrupted the oxidative balance by increasing ROS and mitochondrial injury. The result was a reduction in ATP and failure to provide sufficient energy protection for cardiomyocytes.

Hydrogen peroxide and water availability effect on vegetative growth of soybean [Glycine max (L.) Merr.] Variety Deja 1

Soybean plant [Glycine max (L.) Merr.] Is a food crop that is a source of fat, protein, and minerals. Drought stress is a major obstacle in the cultivation of soybean plants, which causes the synthesis of excessive amounts of Reactive Oxygen Species (ROS) which triggers oxidative stress. Hydrogen peroxide (H2O2) is the most stable ROS, in low concentrations it can act as a signaling molecule and activate an antioxidant defense system to protect plants from oxidative stress. The study was conducted at the Plant Structure and Function Biology Laboratory of Diponegoro University. The study aims to determine the effect of H2O2 treatment on the condition of different levels of water availability on the vegetative growth of soybean plants variety Deja 1. Research using a completely randomized design (CRD) 4x2 factorial pattern. The first factor is H2O2 concentration (0 0.5 1 and 2 mM). The second factor is the level of water availability (100 and 35% of field capacity). Each treatment was repeated 5 times. Quantitative data were analyzed by Analysis of Variance (ANOVA) followed by DMRT test at 95% confidence level. The results showed that there was an interaction between the H2O2 concentration factor and the level of water supply to the canopy fresh weight. The 2 mM H2O2 treatment at 100% water availability and 1 mM H2O2 with 35% water availability increased vegetative growth as indicated by the canopy and root fresh weight parameters, number of leaves, stomata opening width, relative water content. Based on the results of the study it can be stated that the exogenous H2O2 treatment of leaves with certain concentrations at all different levels of water availability can increase the vegetatif growth of soybean variety of Deja 1.

Effects of H2O2 treatment on the temperature-dependent behavior of carrier transport and the optoelectronic properties for sol–gel grown MoS2/Si nanowire/Si devices

The effects of H2O2 treatment on the temperature-dependent behavior of carrier transport and the optoelectronic properties of a MoS2/Si nanowire (SiNW)/n-Si device are studied. The MoS2 thin films are prepared using the sol–gel method. The thermionic emission–diffusion model is the dominant process in the MoS2/SiNW/n-Si device when there is no H2O2 treatment. However, carrier transport in MoS2/SiNW/n-Si devices that are subject to H2O2 treatment is dominated by thermionic emission, so it demonstrates reliable rectification. Passivation of the SiNW surface increases the responsivity to solar irradiation. There is a low trap density at the MoS2/SiNW interfaces so the increase in photocurrent density for the MoS2/SiNW/n-Si device that is subject to H2O2 treatment is due to greater internal power conversion efficiency. The photo-response results for MoS2/SiNW/n-Si devices that are subject to (are not subject to) H2O2 treatment confirm that the decay in the photocurrent is due to the dominance of long-lifetime (short-lifetime) charge trapping. MoS2/SiNW/n-Si devices that are subject to H2O2 treatment exhibit reliable responsivity to solar irradiation.

Surface properties of SiO2 with and without H2O2 treatment as gate dielectrics for pentacene thin-film transistor applications

The effect of H2O2 treatment on the surface properties of SiO2 is studied. H2O2 treatment leads to the formation of Si(OH)x at the SiO2 surface that serves to reduce the number of trap states, inducing the shift of the Fermi level toward the conduction band minimum. H2O2 treatment also leads to a noticeable reduction in the value of the SiO2 capacitance per unit area. The effect of SiO2 layers with H2O2 treatment on the behavior of carrier transports for the pentacene/SiO2–based organic thin-film transistor (OTFT) is also studied. Experimental identification confirms that the shift of the threshold voltage towards negative gate-source voltages is due to the reduced number of trap states in SiO2 near the pentacene/SiO2 interface. The existence of a hydrogenated layer between pentacene and SiO2 leads to a change in the pentacene-SiO2 interaction, increasing the value of the carrier mobility.

Effects of interface modification on electrical and optoelectronic properties of p-type CuAlO2/n-type Si heterojunction devices

The effect of interface modification on the electrical properties of heterojunction diodes based on the p-type CuAlO2 and n-type Si is investigated. Compared with the CuAlO2/Si device without H2O2 treatment, the CuAlO2/Si device with H2O2 treatment exhibits a better rectification behavior. The forward-bias current–voltage characteristics can be explained on the basis of the space charge limited current theory for CuAlO2/Si device without H2O2 treatment. However, the thermionic emission model is the dominant process in this fabricated CuAlO2/Si device with H2O2 treatment. The enhanced device performance is mainly the result of the formation of Si–O bonds that serves to reduce the number of interface states. The effect of H2O2 treatment on the sensitivity to solar irradiation and the response time for CuAlO2/Si devices is also studied. An increase in the values of photocurrent and photosensitivity is attributed to the rectification performance improvement that results from interface passivation.

Effects of H2O2 treatment on the optoelectronic property of poly(3-hexylthiophene) doped with the reduced graphene oxide sheets/Si-nanowire arrays/n-type Si diodes

The effect of H2O2 treatment on the optoelectronic property of the poly(3-hexylthiophene) doped with reduced graphene oxide sheets (P3HT:RGO)/Si-nanowire (SiNW) arrays/n-type Si diode was examined. SiNW surface passivation influences device performance. Compared to P3HT:RGO/SiNWs/n-type Si diodes, P3HT:RGO/H2O2-treated SiNWs/n-type Si diodes exhibit much higher photoconductivity. The results revealed that SiNW surface passivation influences the photoconductivity by reducing the number of electron traps that serve to decrease the photocurrent time constant. High responsivity thus originates from efficient light absorption and carrier collection.

Effects of H2O2 treatment on the optical and structural properties of ZnO nanorods and the electrical properties of conductive polymer/ZnO-nanorod array diodes

The effect of H2O2 treatment on the electrical property of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS)/ZnO-nanorod array diodes was investigated in this study. The effect of H2O2 treatment on the optical and structural properties of ZnO nanorods was also examined. It is shown that H2O2 treatment may lead to the reduced number of oxygen interstitials, improving the quality of ZnO nanorods. Consequently, the PEDOT:PSS/H2O2-treated ZnO-nanorod array diode shows a better rectifying behavior than the PEDOT:PSS/ZnO-nanorod array diode, which can be interpreted by interface passivation.

The Role of ROS in Ionizing Radiation-Induced VLA-4 Mediated Adhesion of RAW264.7 Cells to VCAM-1 Under Flow Conditions

Alteration of adhesion molecule expression on endothelial cells has a direct connection with ionizing radiation-induced atherosclerosis, which is an adverse effect observed after radiotherapy. However, minimal attention has been given to monocytes/macrophages role in atherosclerosis development, which are exposed to the radiation at the same time. Under flow conditions using a parallel plate flow chamber to mimic physiological shear stress, we demonstrate here that the avidity between very late antigen-4 (VLA-4) of RAW264.7 cells and its ligand vascular cell adhesion molecule-1 (VCAM-1), was increased after low dose (0.5 Gy) irradiation, but was reduced after higher dose (5 Gy) treatment of ionizing radiation despite the fact that the surface expression of VLA-4 was up-regulated at 5 Gy of ionizing radiation. Treating the cells with free radical scavenger N-acetylcysteine had no effect on VLA-4 expression, but did reduce the avidity between RAW264.7 cells and VCAM-1 to a similar level, independent of ionizing radiation dose. The effect of H(2)O(2) treatment (from 1-100 μM) on RAW264.7 cell adhesion to VCAM-1 generated a similar bell-shaped graph as ionizing radiation. These results suggest that ionizing radiation regulates adhesive interactions between VLA-4 and VCAM-1, and that reactive oxygen species might function as a regulator, for this increased adhesiveness but with altered expression of integrin not play a major role.

Differential Effect of Paraquat and Hydrogen Peroxide on the Oxidative Stress Response in Vibrio Cholerae Non O1 26/06

ABSTRACTVibrio cholerae non O1 26/06, a non-pathogenic strain, was subjected to treatment by different concentration of paraquat (PQ) and H2O2. Exposure to PQ for 1 h caused induction of reactive oxygen species (ROS) such as superoxide anion radical (•O2−) and H2O2. At the same time, second stress factor significantly inhibited •O2− production and enhanced the intracellular H2O2 content. The enhanced ROS generation resulted in a significant increase in the levels of oxidatively damaged proteins in comparison to the control variant. Thus, the exposure of V. cholerae cells to PQ and H2O2 promoted oxidative stress. Cell response against this stress includes activation of antioxidant enzyme defence. The treatment with PQ concentrations in the range of 0 - 5 mM resulted mainly in activation of SOD, but not noticeably changed CAT activity in V. cholerae non-O1 26/06. In contrast, effect of H2O2treatment on antioxidant enzyme synthesis in our Vibrio strain was still much more pronounced for CAT than for SOD. Therefore, oxidative stress responses induced by •O2− (generated intracellularly by PQ) and H2O2 demonstrated differential adaptation of Vibrio cells to different toxic agents.

Abstract A55: Differential regulation of survivin by reactive oxygen species in breast cancer cells

Abstract Survivin is an anti-apoptotic protein that is highly expressed in most malignant tumors but minimally expressed in normal tissues. Here, we investigate how induced oxidative stress in the form of hydrogen peroxide (H2O2) affects survivin expression levels in the MCF-7 breast cancer cell line. Numerous studies have demonstrated that intracellular H2O2 is a key regulator of signal transduction however its putative role in oncogenesis remains controversial. Conflicting reports have suggested that altering intracellular H2O2 levels can both inhibit and promote apoptosis in cancer cells. Recent studies have shown that compounds that raise cancer cells' intracellular H2O2 levels may make them more susceptible to chemotherapy, while studies at the molecular level show that an increase in intracellular H2O2 activates key oncogenes that block regulated apoptosis and promote an environment optimal for malignant transformation. Based on these reports, we investigated the effects of H2O2 treatment on survivin expression in MCF-7 cells under two different conditions 1) normal proliferation in complete media, 2) cell-cycle arrest by 16-hour serum starvation. Our results show that H2O2 treatment in quiescent cells induced survivin expression in a dose-dependent manner. By contrast, H2O2 treatment in proliferating cells led to a dose-dependent decrease in survivin expression. This result was unexpected as reports indicate that survivin expression is highly induced by growth factors present in serum-complemented media. Further investigation into potential upstream signaling mediators revealed that activation of extracellular signal related kinases 1 and 2 (ERK1/2) may play an important role in H2O2-induced survivin expression. We observed an increase in ERK1/2 phosphorylation that directly corresponded to an increase in survivin expression in serum-deprived cells. However, phospho-ERK1/2 levels remained relatively constant in proliferating MCF-7 cells despite a dose-dependent decrease in survivin expression. One possible explanation for this difference is a dramatic reduction in endogenous H2O2 levels following serum-deprivation. Compared to normal cells, cancer cells have a significantly higher level of intracellular H2O2 potentially making them more susceptible to apoptosis following increased oxidative stress. This mechanism may account for the dose-dependent decrease in survivin expression observed in MCF-7 cells treated with H2O2 in the presence of complete media. However, growth factor withdrawal decreases intracellular H2O2 levels. Therefore, under conditions of serum deprivation, H2O2 may activate mitogen-activated protein (MAP) kinase signal transduction cascades that promote growth and proliferation via oxidative stress signals. Together, our results support the hypothesis that endogenous levels of H2O2 may play a critical role in how cancer cells respond to treatment regulated by the MAP kinase pathway. Based on this model, agents that increase H2O2 levels in rapidly dividing cancer cells should be explored as an adjunct to chemotherapy, representing a novel approach to induce selective apoptosis by exploiting the oxidative environment tumor cells manifest in order to sustain their excessive metabolic demands. Citation Information: Cancer Res 2009;69(23 Suppl):A55.

Reactive Oxygen Species Facilitate Adipocyte Differentiation by Accelerating Mitotic Clonal Expansion

Growth-arrested 3T3-L1 preadipocytes rapidly express CCAAT/enhancer-binding protein-beta (C/EBPbeta) upon hormonal induction of differentiation. However, the DNA binding activity of C/EBPbeta is not activated until the cells synchronously reenter S phase during the mitotic clonal expansion (MCE) phase of differentiation. In this period, C/EBPbeta is sequentially phosphorylated by MAPK and glycogen synthase kinase-3beta, inducing C/EBPbeta DNA binding activity and transcription of its target genes. Because the DNA binding activity of C/EBPbeta is further enhanced by oxidation in vitro, we investigated how redox state affects C/EBPbeta DNA binding and MCE during adipogenesis. When 3T3-L1 cells were treated with H(2)O(2) and hormonal stimuli, differentiation was accelerated with increased expression of peroxisome proliferator-activated receptor gamma. Interestingly, cell cycle progression (S to G(2)/M phase) was markedly enhanced by H(2)O(2), whereas antioxidants caused an S phase arrest during the MCE. H(2)O(2) treatment resulted in the early appearance of a punctate pattern observed by immunofluorescent staining of C/EBPbeta, which is a hallmark for C/EBPbeta binding to regulatory elements, whereas a short antioxidant treatment rapidly dispersed the centromeric localization of C/EBPbeta. Consistently, reactive oxygen species production was increased during 3T3-L1 differentiation. Our results indicate that redox-induced C/EBPbeta DNA binding activity, along with the dual phosphorylation of C/EBPbeta, is required for the MCE and terminal differentiation of adipocytes.

Lethal and mutagenic action of hydrogen peroxide on Haemophilus influenzae

The lethal and mutagenic effects of H2O2 on wild-type Haemophilus influenzae Rd and on uvr1, uvr2, rec1, and rec2 mutant strains were studied. The first two mutants are sensitive to UV, and the second two are defective in recombination. Rd, urv1, and rec1 strains were more sensitive to the killing effect of H2O2 treatment than were uvr2 and rec2 strains. There were peaks of mutagenesis at two H2O2 concentrations over a range of 30 to 275 mM. Our results suggest a specific repair of H2O2 damage that is independent of the Uvr2 and Rec2 gene products. Sensitivity to the killing effect of H2O2 and to the lethal action of near-UV light were similar for Rd and uvr1 strains. This finding suggests that the mechanisms of killing by and repair of H2O2 damage may have some overlap with those of near-UV radiation.