Modulation Of Oxidative Stress Response Research Articles

Comparative in vitro toxicity of compositionally distinct thermal spray particulates in human bronchial cells

Thermal spray, in general, is a process that involves forcing a melted substance, such as metal or ceramic in the form of wire or powder, onto the surface of a targeted object to enhance its desired surface properties. In this paper, the melted substance is metal wire generated by an electric arc and forcibly coated on a rotary iron substrate using compressed air. This thermal process is referred to as double-wire arc thermal spray. The particles generated through these methods fall within the nanometer to micrometer agglomerate size range. There is concern regarding potential human health outcomes as these particles exhibit a similarity in particle morphology to welding fumes. Thermal spray wires with zinc (PMET540), iron and chromium (PMET731), and nickel (PMET885) as primary metal compositions were used to generate particulate via an electric arc wire thermal spray generator for exposure to human bronchial cells (BEAS-2B) to examine comparative toxicity ranging from 0-200µg/mL. Resulting cellular viability was assessed through live cell counts, and percent cytotoxicity was measured as a function of LDH release. Oxidative stress, genotoxicity, and alteration in total antioxidant capacity were evaluated through DNA damage (COMET analysis) and antioxidant concentration at 0, 3.125, 25, and 100µg/mL. Protein markers for endothelin-1 (ET-1), interleukin-6 (IL-6), and interleukin-8 (IL-8) were also assessed to determine inflammation and endothelial alteration. Resultsindicate modulation of oxidative stress response in a material and dose dependent manner. PMET540 exhibited the greatest cytotoxic effect between wires and across doses. DNA damage and antioxidant concentration induced by PMET540 were significantly higher than other wires at higher doses (DNA damage increased at 25 and 100µg/mL; Antioxidant concentration increased at 100µg/mL). However, ET-1 concentration significantly increased only after application of 100µg/mL PMET885. IL-6 and IL-8 were most highly expressed in BEAS2B culture after 25µg/mL exposure to PMET540 (99.4% Zn). This data suggests that metal composition of thermal spray wires dictates the diverse response in human bronchial cells.

Tripartite interactions between grapevine, viruses, and arbuscular mycorrhizal fungi provide insights into modulation of oxidative stress responses

Arbuscular mycorrhizal fungi (AMF) can be beneficial for plants exposed to abiotic and biotic stressors. Although widely present in agroecosystems, AMF influence on crop responses to virus infection is underexplored, particularly in woody plant species such as grapevine. Here, a two-year greenhouse experiment was set up to test the hypothesis that AMF alleviate virus-induced oxidative stress in grapevine. The ‘Merlot’ cultivar was infected with three grapevine-associated viruses and subsequently colonized with two AMF inocula, containing one or three species, respectively. Five and fifteen months after AMF inoculation, lipid peroxidation - LPO as an indicator of oxidative stress and indicators of antioxidative response (proline, ascorbate - AsA, superoxide dismutase - SOD, ascorbate- APX and guaiacol peroxidases - GPOD, polyphenol oxidase - PPO, glutathione reductase - GR) were analysed. Expression of genes coding for a stilbene synthase (STS1), an enhanced disease susceptibility (EDS1) and a lipoxygenase (LOX) were determined in the second harvesting. AMF induced reduction of AsA and SOD over both years, which, combined with not AMF-triggered APX and GR, suggests decreased activation of the ascorbate-glutathione cycle. In the mature phase of the AM symbiosis establishment GPOD emerged as an important mechanism for scavenging H2O2 accumulation. These results, together with reduction in STS1 and increase in EDS1 gene expression, suggest more efficient reactive oxygen species scavenging in plants inoculated with AMF. Composition of AMF inocula was important for proline accumulation. Overall, our study improves the knowledge on ubiquitous grapevine-virus-AMF systems in the field, highlighting that established functional AM symbiosis could reduce virus-induced stress.

Exogenous Glutathione Enhances Salt Tolerance in Kenaf by Mediating Modulation of Oxidative Stress Response and DNA Methylation

Exogenous Glutathione Enhances Salt Tolerance in Kenaf by Mediating Modulation of Oxidative Stress Response and DNA Methylation

Neuroprotective effects of G9a inhibition through modulation of peroxisome-proliferator activator receptor gamma-dependent pathways by miR-128.

JOURNAL/nrgr/04.03/01300535-202419110-00033/figure1/v/2024-03-08T184507Z/r/image-tiff Dysregulation of G9a, a histone-lysine N-methyltransferase, has been observed in Alzheimer's disease and has been correlated with increased levels of chronic inflammation and oxidative stress. Likewise, microRNAs are involved in many biological processes and diseases playing a key role in pathogenesis, especially in multifactorial diseases such as Alzheimer's disease. Therefore, our aim has been to provide partial insights into the interconnection between G9a, microRNAs, oxidative stress, and neuroinflammation. To better understand the biology of G9a, we compared the global microRNA expression between senescence-accelerated mouse-prone 8 (SAMP8) control mice and SAMP8 treated with G9a inhibitor UNC0642. We found a downregulation of miR-128 after a G9a inhibition treatment, which interestingly binds to the 3' untranslated region (3'-UTR) of peroxisome-proliferator activator receptor γ (PPARG) mRNA. Accordingly, Pparg gene expression levels were higher in the SAMP8 group treated with G9a inhibitor than in the SAMP8 control group. We also observed modulation of oxidative stress responses might be mainly driven Pparg after G9a inhibitor. To confirm these antioxidant effects, we treated primary neuron cell cultures with hydrogen peroxide as an oxidative insult. In this setting, treatment with G9a inhibitor increases both cell survival and antioxidant enzymes. Moreover, up-regulation of PPARγ by G9a inhibitor could also increase the expression of genes involved in DNA damage responses and apoptosis. In addition, we also described that the PPARγ/AMPK axis partially explains the regulation of autophagy markers expression. Finally, PPARγ/GADD45α potentially contributes to enhancing synaptic plasticity and neurogenesis after G9a inhibition. Altogether, we propose that pharmacological inhibition of G9a leads to a neuroprotective effect that could be due, at least in part, by the modulation of PPARγ-dependent pathways by miR-128.

Multi-omics analysis reveals activation of jasmonate synthesis and modulation of oxidative stress responses in boron deficient pea shoots

Boron (B) is vital for plant growth and development. Understanding aboveground tissue responses to B deficiency can offer insights into enhancing plant productivity under B-limited conditions. Here we show from comprehensive metabolomics analysis that during B deficiency treatment the number of differentially expressed metabolites (DEMs) increases from 64 to 193 in pea shoots. Boron deficiency intensified oxidative stress and led to decreased ascorbate and glutathione levels. Integrative metabolomic and transcriptomic analyses revealed activation of the phenylpropanoid biosynthesis and α-linolenic acid metabolic pathways under B deficiency. Metabolites of the phenylpropanoid pathway, including p-coumaryl alcohol and sinapic acid, increased, accompanied by upregulation of related biosynthetic genes. A decline in total flavonoid content suggested that the activation of phenylpropanoid synthesis might indicate increased lignin accumulation, thus affecting cell wall metabolism. The alterations in these pathways at specific time point highlighted the dynamic resource allocation caused by B deficiency, providing insights into metabolic reprogramming in pea shoot apices. In the α-linolenic acid pathway, B deficiency led to accumulation of 17-hydroxylinolenic acid, jasmonic acid (JA), and jasmonoyl-L-isoleucine, with upregulated JA biosynthesis genes. Jasmonates are proposed to play a key role in reprogramming shoot development particularly modulating membrane and cell wall structure and function under B deficiency. Increased levels of oxidation products of linoleic acid suggest changes to membrane structure and are also consistent with changes to the redox status of cells under B deficiency. Collectively, our findings elucidated intricate B deficiency responses at both the metabolome and transcriptome levels and identified potential targets for breeding crops tolerant to B deficiency, including jasmonate signalling, phenylpropanoid biosynthesis, and antioxidant capacity.

Environmental Signals Act as a Driving Force for Metabolic and Defense Responses in the Antarctic Plant Colobanthus quitensis.

During evolution, plants have faced countless stresses of both biotic and abiotic nature developing very effective mechanisms able to perceive and counteract adverse signals. The biggest challenge is the ability to fine-tune the trade-off between plant growth and stress resistance. The Antarctic plant Colobanthus quitensis has managed to survive the adverse environmental conditions of the white continent and can be considered a wonderful example of adaptation to prohibitive conditions for millions of other plant species. Due to the progressive environmental change that the Antarctic Peninsula has undergone over time, a more comprehensive overview of the metabolic features of C. quitensis becomes particularly interesting to assess its ability to respond to environmental stresses. To this end, a differential proteomic approach was used to study the response of C. quitensis to different environmental cues. Many differentially expressed proteins were identified highlighting the rewiring of metabolic pathways as well as defense responses. Finally, a different modulation of oxidative stress response between different environmental sites was observed. The data collected in this paper add knowledge on the impact of environmental stimuli on plant metabolism and stress response by providing useful information on the trade-off between plant growth and defense mechanisms.

The multifaceted role of reactive oxygen species in tumorigenesis.

Redox homeostasis is an essential requirement of the biological systems for performing various normal cellular functions including cellular growth, differentiation, senescence, survival and aging in humans. The changes in the basal levels of reactive oxygen species (ROS) are detrimental to cells and often lead to several disease conditions including cardiovascular, neurological, diabetes and cancer. During the last two decades, substantial research has been done which clearly suggests that ROS are essential for the initiation, progression, angiogenesis as well as metastasis of cancer in several ways. During the last two decades, the potential of dysregulated ROS to enhance tumor formation through the activation of various oncogenic signaling pathways, DNA mutations, immune escape, tumor microenvironment, metastasis, angiogenesis and extension of telomere has been discovered. At present, surgery followed by chemotherapy and/or radiotherapy is the major therapeutic modality for treating patients with either early or advanced stages of cancer. However, the majority of patients relapse or did not respond to initial treatment. One of the reasons for recurrence/relapse is the altered levels of ROS in tumor cells as well as in cancer-initiating stem cells. One of the critical issues is targeting the intracellular/extracellular ROS for significant antitumor response and relapse-free survival. Indeed, a large number of FDA-approved anticancer drugs are efficient to eliminate cancer cells and drug resistance by increasing ROS production. Thus, the modulation of oxidative stress response might represent a potential approach to eradicate cancer in combination with FDA-approved chemotherapies, radiotherapies as well as immunotherapies.

Contaminant accumulation and biological responses in Atlantic cod (Gadus morhua) caged at a capped waste disposal site in Kollevåg, Western Norway

The aim of this study was to assess whether fish in Kollevåg, a sheltered bay on the western coast of Norway, previously utilized as a waste disposal site, could be affected by environmental contaminants leaking from the waste. Farmed, juvenile Atlantic cod (Gadus morhua) were caged for six weeks at three different locations in Kollevåg bay and at one reference location. Sediments and cod samples (bile and liver) were analyzed for polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), per-and polyfluoroalkyl substances (PFASs) and polycyclic aromatic hydrocarbon (PAH) metabolites, revealing a contamination gradient at the four stations. Furthermore, hepatosomatic index (HSI) and Fulton's condition factor (CF) were significantly lower in cod caged closest to the disposal site. Levels and activities of biomarker proteins, such as vitellogenin (Vtg), metallothionein (Mt), and biotransformation and oxidative stress enzymes, including cytochrome P450 1a and 3a (Cyp1a, Cyp3a), glutathione s-transferase (Gst) and catalase (Cat), were quantified in blood plasma and liver tissue. Hepatic Cat and Gst activities were significantly reduced in cod caged at the innermost stations in Kollevåg, indicating modulation of oxidative stress responses. However, these results contrasted with reduced hepatic lipid peroxidation. Significant increases in transcript levels were observed for genes involved in lipid metabolism (fasn and acly) in cod liver, while transcript levels of ovarian steroidogenic enzyme genes such as p450scc, cyp19, 3β-hsd and 20β-hsd showed significant station-dependent increases. Cyp1a and Vtg protein levels were however not significantly altered in cod caged in Kollevåg. Plasma levels of estradiol (E2) and testosterone (T) were determined by enzyme immunoassay (EIA) and showed elevated E2 levels, but only at the innermost station. We conclude that the bay of Kollevåg did not fullfill adequate environmental condition based on environmental quality standards (EQSs) for chemicals in coastal waters. Following a six weeks caging period, environmental contaminants accumulated in cod tissues and effects were observed on biomarker responses, especially those involved in reproductive processes in cod ovary.

Toxicity of coal fly ash (CFA) and toxicological response of switchgrass in mycorrhiza-mediated CFA-soil admixtures

Increasing support for the use of Coal fly ash (CFA) in agriculture has necessitated a better understanding of the effects of the CFA in various cropping schemes. Experiments were conducted to assess mutagenic response of a mutant strain of Salmonella enterica serovar Typhimurium (TA100) to varying concentrations of CFA-water extracts, determine oxidative stress in switchgrass (Panicum virgatum L.) at varying levels of CFA-soil admixtures, and evaluate mycorrhiza-mediated modulation of oxidative stress responses of CFA-grown switchgrass. The TA100 exposed to 0%, 5%, 10%, 15%, 20% and 25% (w/v) CFA-water extracts elicited significant (p < 0.05) mutagenic responses at 20% and 25% extract levels but not below the 15% level. In greenhouse pot experiment, CFA-soil admixtures at 7.5% and 15% (w/w) significantly (p < 0.05) decreased the activities of superoxide dismutase (SOD) by 19.1% and 28.3% respectively, compared to control soil (0% w/w CFA/soil). Under the same conditions, activities of glutathione peroxidase (GPx) decreased by 75.9% and 66.9%. In contrast to the antioxidant enzyme activities, levels of malondialdehyde (MDA) an indicator of lipid peroxidation increased significantly (p < 0.05) by 30.49% and 38.38%. Inoculation of 7.5% and 15% CFA-soil admixtures with arbuscular mycorrhizal fungi (AMF), Rhizophaga clarus enhanced the activities of both SOD and GPx in the switchgrass, while it significantly (p < 0.05) reduced the levels of MDA. The study demonstrated that incorporation of CFA (at concentrations considered to be non-mutagenic against TA100) as soil amendment produced concentration-dependent oxidative stress responses in switchgrass; however, inoculation of the CFA-soil admixtures with AMF significantly modulated the oxidative stress responses.

P 075 - Modulation of oxidative stress response in neurodevelopment disorders. The case of the Rett syndrome variants: MECP2 and CDKL5

Rett syndrome (RTT) variants are rare neurodevelopmental disorders caused by mutations in the X-linked MECP2 or CDKL5 genes. Because CDKL5 mediates MeCP2 phosphorylation and CDKL5 is a MeCP2-repressed target gene, it is possible that these proteins share similar molecular pathways. Altered redox status and subclinical inflammation seem to be common denominators between the two RTT variants: increased systemic levels of 4-HNE protein adducts and dysregulated cytokine profiles were reported. The altered redox homeostasis appears to be a critical player in the posttranslational modifications of SRB1, a specific high-density lipoproteins receptor, leading to altered serum lipid profiles in both variants. Although these parallels, Nrf2 system shows an impaired function in both disorders, but with some divergent aspects. CDKL5 show an inability to induce a proper defensive response with a significantly low nuclear Nrf2 translocation after oxidative challenge, while in MECP2 a sustained Nrf2 activation observed in basaline and upon oxidative stress stimulus. These findings reveal common defective pathways related to redox homeostasis between MECP2 and CDKL5. At present, the molecular basis of the discrepancy in the Nrf2 is unknown and requires further investigation in the light of the possibility to develop new therapeutic strategies for these devastating disorders without a cure.

WhiB4 Regulates the PE/PPE Gene Family and is Essential for Virulence of Mycobacterium marinum

During the course of infection, pathogenic mycobacteria including Mycobacterium tuberculosis (M. tb) encounter host environments of variable oxygen tension, ranging from the hypoxic center of granulomas to the most oxygenated region in the lung cavities. Mycobacterial responses to changes of oxygen tension are critically related to infection outcomes, such as latency and reactivation. WhiB4 is an iron-sulfur containing transcription factor that is highly sensitive to oxygen exposure. In this study, we found that WhiB4 of Mycobacterium marinum (M. marinum), a pathogenic mycobacterial species that is closely related to M. tb, is required for its virulence. M. marinum ΔwhiB4 exhibited defective intracellular replication in macrophages and diminished virulence in zebrafish. Histology analysis revealed that the host had successfully controlled ΔwhiB4 bacteria, forming well-organized granulomas. RNA-seq analysis identified a large number of pe/ppe genes that were regulated by WhiB4, which provides an explanation for the essential role of WhiB4 in M. marinum virulence. Several antioxidant enzymes were also upregulated in ΔwhiB4, supporting its role in modulation of oxidative stress response. Taken together, we have provided new insight into and proposed a model to explain the physiological role of WhiB4.

Modulation of Oxidative Stress Responses by Vitamin E, or Vitamin A plus Vitamin C Treatment in Human Retinal Pigment Epithelial Cells

The purpose of this study was to characterize the potential of vitamins to protect the retinal pig-ment epithelium (RPE) from oxidative stress (OS). We have previously shown that OS induces the expression of AP1 transcription factors (FOSB, CFOS and ATF3), but is modulated by pretreatment with vitamin C (200 μM). We propose that OS-induced AP1 expression can be used as a biomarker of OS to test the efficacy of vitamins to limit the impact of OS in the RPE. Here we examined the efficacy of vitamin E or combined vitamin A plus vitamin C to modulate OS-induced AP1 expression in the RPE. We pretreated human ARPE-19 cells with vitamin E (0 - 7.5 μM) or with combined vitamin A (10 or 15 μM) plus vitamin C (50 or 100 μM) for 3 days prior to exposure to 500 μM H2O2 OS for 1 - 4 h. AP1 expression was assessed using qRT-PCR. Pretreatment with ≥2.5 μM vitamin E significantly decreased OS-induced AP1 expression at 1 - 4 h OS, compared to controls. Lower doses of vitamin E were ineffective at modulating OS responses. Pretreatment with 100 μM vitamin C combined with 15 μM vitamin A protected RPE cells from OS-induced AP1 expression. There is an additive and potentially protective effect of 100 μM vitamin C and 15 μM vitamin A on FOSB expression at 4 h, and a potentially protective effect of 100 μM vitamin C and 15 μM vitamin A on CFOS expression at 1 h OS. A protective effect was also seen with 15 μM vitamin A pretreatment alone on ATF3 expression. Thus, “sub-therapeutic” levels of multiple vitamins may protect RPE cells better than higher doses of a single vitamin. This OS-induced AP1 expression biomarker assay may be useful to identify complex antioxidant formulations as therapeutics for degenerative diseases that are thought to be caused by OS, like age-related macular degeneration.

Pharmacological Modulation of Oxidative Stress Response in Minimally Invasive Surgery

This systematic review aims to synthesize the data on the effectiveness of pharmacological modulation of stress response in minimally invasive surgery. Eligible trials were clinical trials randomized or not or experimental trials that investigated the effect of pharmacological agents on modulation of surgical stress response to minimally invasive surgery. No clinical trials were identified. Eight experimental trials met the inclusion criteria and were obtained in full text. Experimental models were rats or rabbits subjected to pneumoperitoneum, or pneumoretroperitoneum, not to a whole operation. Pharmacological modulation of surgical stress response was attempted with erythromycin, melatonin, mesna, verapamil, pentoxifylline, N-acetylcysteine, and zinc. All the pharmacological agents, except pentoxifylline, seemed to reduce oxidative stress markers. However, only mesna pretreatment prevented oxidative stress, because oxidative stress markers remained in the sham levels. Contrasting data were obtained for pentoxyphilline. In conclusion, available data suggest that pharmacological modulation of surgical stress response to minimally invasive surgery might be feasible.

Modulation of oxidative stress responses in the human retinal pigment epithelium following treatment with vitamin C

Oxidative stress (OS) in the retina plays an important role in the development and progression of age-related macular degeneration (AMD). Our previous work has shown that OS can quantitatively regulate the expression of AP-1 family genes in the retinal pigment epithelium (RPE). In this study, we sought to determine whether AP-1 genes can be used as cellular biomarkers of OS to evaluate the efficacy of ascorbate, the major aqueous-phase antioxidant in the blood, in reducing OS in RPE cells in vitro. Human ARPE19 cells were pretreated with increasing levels of ascorbate (0-500 µM) for 3 days which was then removed from the medium. OS was induced 24 h later by the addition of hydrogen peroxide for 1-4 h, to bring the final media concentration of H(2)O(2) to 500 µM. FosB, c-Fos, and ATF3 gene expression was examined from 0 to 24 h after OS. Pretreatment with 200 µM ascorbate maximally reduced the transcriptional OS response of AP-1 genes by up to 87% after 1 and 4 h, compared to controls. One hundred micromolar of ascorbate provided a statistically significant, but far more modest effect. Ascorbate supplementation of 100-200 µM appears to strongly inhibit OS-induced activation of AP-1 in vitro, but pretreatment with higher levels of ascorbate conferred no additional advantage. These studies suggest that there are optimal levels of antioxidant supplementation to the RPE in vitro. Laboratory assays based upon transcription factor biomarkers may be useful to define beneficial molecular responses to new antioxidants, alternative dosing regimens, and to explore therapeutic efficacy in OS models in vitro.

Nrf2, a Critical Regulator of Oxidative Stress, Is Required for HSC Function and Cytokine Response.

Abstract 1492Poster Board I-515Previous studies have established an important role for reactive oxygen species (ROS) in regulating the function and life-span of hematopoietic stem cells (HSC). Nuclear factor erythroid-2–related factor 2 (Nrf2) is a redox-sensitive transcription factor that regulates cellular responses to ROS and detoxification pathways implicated in chemoresistance, however, its role in normal stem cells is unknown. We analyzed Nrf2null mice and found increased total bone marrow cellularity, cKit+Sca1+Lin− (KSL) stem-progenitor cells, and long-term quiescent HSC (CD34−KSL) compared to wild type mice (p<0.05). Transplantation of equal numbers of KSL cells from Nrf2wt and Nrf2null resulted in a five-fold decrease in peripheral blood chimerism from Nrf2null derived cells at 16 weeks (15% wild type vs. 3% null, p<0.05). Unlike other models of deficiencies in genes associated with ROS handling, such as ATM or the FoxO family of transcription factors, basal ROS levels were not elevated in Nrf2null HSC. However, Nrf2null bone marrow cells demonstrated increased sensitivity to induced oxidative stress and in vitro treatment with H2O2 resulted in a 2 fold decrease in colony formation in methylcellulose. We also examined the in vivo sensitivity of Nrf2null cells to oxidative stress by irradiating (400 rads) stably chimeric mice 20 weeks following transplantation with either Nrf2wt or Nrf2null HSC. Mice receiving Nrf2null HSC demonstrated a 50% decrease in peripheral blood chimerism at 4 months following radiation compared to no change in Nrf2wt recipients (p<0.05) confirming that loss of Nrf2 leads to increased sensitivity to oxidative stress. Microarray gene expression analysis from Nrf2wt and Nrf2null mice revealed down regulation of the G-CSF cytokine receptor in Nrf2null HSC and suggested that defective cytokine signaling may contribute to the HSC dysfunction seen in Nrf2null bone marrow cells. To test this hypothesis, we attempted to rescue the function of Nrf2null HSC by treating mice with exogenous G-CSF. Nrf2wt and Nrf2null mice were treated with one week of daily G-CSF and then HSC were harvested and transplanted. In contrast to the defects in engraftment of untreated Nrf2null HSC, there was no significant difference in peripheral blood chimerism following transplantation of G-CSF treated Nrf2wt or Nrf2null HSC, thus demonstrating that G-CSF treatment could rescue the HSC defect in mutant mice. In conclusion, the Nrf2 transcription factor appears to be a novel and essential regulator of normal HSC function through the modulation of oxidative stress response and cytokine signaling. Disclosures:No relevant conflicts of interest to declare.