Excessive Reactive Oxygen Species Formation Research Articles

Inhibition of MMP8 effectively alleviates manic-like behavior and reduces neuroinflammation by modulating astrocytic CEBPD

There is an intrinsic relationship between psychiatric disorders and neuroinflammation, including bipolar disorder. Ouabain, an inhibitor of Na+/K+-ATPase, has been implicated in the mouse model with manic-like behavior. However, the molecular mechanisms linking neuroinflammation and manic-like behavior require further investigation. CCAAT/Enhancer-Binding Protein Delta (CEBPD) is an inflammatory transcription factor that contributes to neurological disease progression. In this study, we demonstrated that the expression of CEBPD in astrocytes was increased in ouabain-treated mice. Furthermore, we observed an increase in the expression and transcript levels of CEBPD in human primary astrocytes following ouabain treatment. Transcriptome analysis revealed high MMP8 expression in human primary astrocytes following CEBPD overexpression and ouabain treatment. We confirmed that MMP8 is a CEBPD-regulated gene that mediates ouabain-induced neuroinflammation. In our animal model, treatment of ouabain-injected mice with M8I (an inhibitor of MMP8) resulted in the inhibition of manic-like behavior compared to ouabain-injected mice that were not treated with M8I. Additionally, the reduction in the activation of astrocytes and microglia was observed, particularly in the hippocampal CA1 region. Excessive reactive oxygen species formation was observed in ouabain-injected mice, and treating these mice with M8I resulted in the reduction of oxidative stress, as indicated by nitrotyrosine staining. These findings suggest that MMP8 inhibitors may serve as therapeutic agents in mitigating manic symptoms in bipolar disorder.

ROS-responsive electrospun poly(amide thioketal) mats for wound dressing applications

Excessive levels of reactive oxygen species (ROS) are usually associated with the inflammatory response during the wound healing process. Therefore, strategies that can locally control the adverse effects of excessive formation of ROS may lead to improved healing times. In this work, ROS-responsive scavenging materials were developed using a degradable poly(amide thioketal) (PATK) polymer. This PATK polymer was prepared using a thioketal (TK) diacid monomer which gives the polymer the ability to be degraded by ROS. This PATK polymer was used to prepare electrospun mats by blending it with the biocompatible poly(ε-caprolactone) (PCL). The developed mats showed good degradability when exposed to an oxidative environment and can also be degraded by a photo-mediated mechanism. Cytotoxicity tests performed in vitro on a fibroblast cell line showed that the mats had no adverse effects on the cells, confirming the potential of these systems for biomedical applications. In addition, the antioxidant capacity of the membranes was also found to be good, which could be relevant for wound dressing applications.

Copine7 deficiency leads to hepatic fat accumulation via mitochondrial dysfunction

ObjectiveMitochondrial dysfunction affects hepatic lipid homeostasis and promotes ROS generation. Copine7 (CPNE7) belongs to the ubiquitous copine family of calcium-dependent phospholipid binding proteins. CPNE7 has a high calcium ion binding affinity and the capacity to scavenge reactive oxygen species (ROS). A recent study reported that abnormalities in fatty acid and lipid metabolism were linked to the gene variant of CPNE7. Therefore, the purpose of this study is to examine the role of Cpne7 in hepatic lipid metabolism based on mitochondrial function. MethodsLipid metabolism, mitochondrial function, and ROS production were investigated in high-fat diet (HFD)-fed Cpne7−/− mice and H2O2-damaged HepG2 hepatocytes following CPNE7 silencing or overexpression. ResultsCpne7 deficiency promoted severe hepatic steatosis in the HFD-induced NAFLD model. More importantly, mitochondrial dysfunction was observed along with an imbalance of mitochondrial dynamics in the livers of HFD-fed Cpne7−/−mice, resulting in high ROS levels. Similarly, CPNE7-silenced HepG2 hepatocytes showed high ROS levels, mitochondrial dysfunction, and increased lipid contents. On the contrary, CPNE7-overexpressed HepG2 cells showed low ROS levels, enhanced mitochondrial function and decreased lipid contents under H2O2-induced oxidative stress. ConclusionsIn the liver, Cpne7 deficiency causes excessive ROS formation and mitochondrial dysfunction, which aggravates lipid metabolism abnormalities. These findings provide evidence that Cpne7 deficiency contributes to the pathogenesis of NAFLD, suggesting Cpne7 as a novel therapeutic target for NAFLD.

Comprehensive Neurotoxicity of Lead Halide Perovskite Nanocrystals in Nematode Caenorhabditis elegans.

To date, all-inorganic lead halide perovskite quantum dots have emerged as promising materials for photonic, optoelectronic devices, and biological applications, especially in solar cells, raising numerous concerns about their biosafety. Most of the studies related to the toxicity of perovskite quantum dots (PeQDs) have focused on the potential risks of hybrid perovskites by using zebrafish or human cells. So far, the neurotoxic effects and fundamental mechanisms of PeQDs remain unknown. Herein, a comprehensive methodology is designed to investigate the neurotoxicity of PeQDs by using Caenorhabditis elegans as a model organism. The results show that the accumulation of PeQDs mainly focuses on the alimentary system and head region. Acute exposure to PeQDs results in a decrease in locomotor behaviors and pharyngeal pumping, whereas chronic exposure to PeQDs causes brood decline and shortens lifespan. In addition, some abnormal issues occur in the uterus during reproduction assays, such as vulva protrusion, impaired eggs left in the vulva, and egg hatching inside the mother. Excessive reactive oxygen species formation is also observed. The neurotoxicity of PeQDs is explained by gene expression. This study provides a complete insight into the neurotoxicity of PeQD and encourages the development of novel nontoxic PeQDs.

Synergistic in Vitro Antioxidant Activity of Linum Usitatissimum and Mentha Spicata

Reactive Oxygen Species (ROS) are free radicals that contain oxygen and easily react with another cell molecule. Excessive ROS formation damages the macromolecules of a cell, like lipids, DNA, and proteins, leading to oxidative stress. Oxidative stress occurs when there is an imbalance between free radical production and the body's ability to neutralize them through anti-oxidants. Oxidative stress can lead to atherosclerosis, Parkinson's disease, rheumatoid arthritis, diabetes, cancer, etc. Synthetic anti-oxidants, such as Butylated hydroxyanisole (BHA), have recently been allegedly dangerous for human health. Thus, the need arises for searching and identifying natural sources of antioxidants, which would be useful for the primary prevention of the above disorders. The main objective of this study is to explore the synergistic in vitro anti-oxidant activity of flaxseed (Linum usitatissimum) and mint (Mentha spicata) combination. It was achieved by performing in vitro spectrophotometric techniques such as ABTS (2,2-azinobis-(3- ethylbenzothiazoline-6-sulfonic acid)) and DPPH(2,2-Diphenyl-1-picrylhydrazyl) H2O2(hydrogen peroxide) and hydroxyl radical scavenging assays. The percentage of inhibition was calculated, and the results were expressed in terms of IC50 (half maximal inhibitory concentration). Although there are numerous studies on the antioxidant properties of Linum usitatissimum and Mentha spicata, there are no reports on their comparative and synergistic antioxidant properties. This study was therefore performed to investigate the comparative and synergistic anti-oxidant properties of Linum usitatissimum and Mentha spicata.

An Overview of Two Old Friends Associated with Platelet Redox Signaling, the Protein Disulfide Isomerase and NADPH Oxidase.

Oxidative stress participates at the baseline of different non-communicable pathologies such as cardiovascular diseases. Excessive formation of reactive oxygen species (ROS), above the signaling levels necessary for the correct function of organelles and cells, may contribute to the non-desired effects of oxidative stress. Platelets play a relevant role in arterial thrombosis, by aggregation triggered by different agonists, where excessive ROS formation induces mitochondrial dysfunction and stimulate platelet activation and aggregation. Platelet is both a source and a target of ROS, thus we aim to analyze both the platelet enzymes responsible for ROS generation and their involvement in intracellular signal transduction pathways. Among the proteins involved in these processes are Protein Disulphide Isomerase (PDI) and NADPH oxidase (NOX) isoforms. By using bioinformatic tools and information from available databases, a complete bioinformatic analysis of the role and interactions of PDI and NOX in platelets, as well as the signal transduction pathways involved in their effects was performed. We focused the study on analyzing whether these proteins collaborate to control platelet function. The data presented in the current manuscript support the role that PDI and NOX play on activation pathways necessary for platelet activation and aggregation, as well as on the platelet signaling imbalance produced by ROS production. Our data could be used to design specific enzyme inhibitors or a dual inhibition for these enzymes with an antiplatelet effect to design promising treatments for diseases involving platelet dysfunction.

In vitro evaluation of coenzyme Q10 on primary fibroblast culture

Chronic inflammation in periodontitis results in continuous production of Reactive Oxygen Species (ROS), so the levels are excessive, causing destruction of the gingiva, periodontal ligament, and alveolar bone through a variety of mechanisms including DNA damage and the formation of proinflammatory cytokine. One way to prevent periodontal tissue damage caused by excessive ROS formation is by administering antioxidants. Coenzyme Q10 is a powerful antioxidant that is beneficial for inhibiting free radicals to prevent the progression of periodontal tissue destruction and accelerate healing processes. The purpose of this study was to evaluate the fibroblast proliferation of the combination of Coenzyme Q10 and vegetable glycerin compared to PerioQ. Materials used were made of original Coenzyme Q10 dissolved in glycerin that was prepared in a ratio of 2:8 and 1:9, and Perio Q as the control. Each group consisted of six samples (n = 6). Primary fibroblasts were derived from healthy gingival tissue. Observations on day-1, -3, and -5 using MTT assay at a wavelength of 550nm. Statistical analysis used a Two-Way ANOVA test followed by a Post Hoc test. The experiment showed the absorbance values were high in all the groups, the highest value was on day 3, namely Coenzyme Q10 at a concentration of 2:8, followed by Coenzyme Q10 at a concentration of 1:9, and PerioQ. The statistical tests showed significant differences in the 3 groups (p < 0.05). It is concluded that Coenzyme Q10 in 1:9 and 2:8 concentrations were both as viable as Perio Q towards primary gingival fibroblast culture.

Circulating Permeability Factors in Focal Segmental Glomerulosclerosis: In Vitro Detection

The recurrence of proteinuria after kidney transplantation in patients with focal segmental glomerulosclerosis (FSGS) is considered proof of the presence of circulating permeability factors (CPFs). The aim of this study is to demonstrate the presence of plasma CPFs using series of invitro assays. Podocytes and endothelial cells (glomerular microvascular endothelial cells [GMVECs]) were incubated with plasma from FSGS patients with presumed CPFs in relapse and remission and from steroid-resistant nephrotic syndrome (SRNS), steroid-sensitive nephrotic syndrome (SSNS), membranous nephropathy (MN), and healthy controls (hCtrls). Cell viability, podocyte actin cytoskeleton architecture, and reactive oxygen species (ROS) formation with or without ROS scavenger were investigated by Cell Counting Kit-8 assay, immunofluorescence staining, and CM-H2DCFDA probing, respectively. Presumed CPF-containing plasma causes a series of events in podocytes but not in GMVECs. These events include actin cytoskeleton rearrangement and excessive formation of ROS, which results in podocyte loss. These effects were solely observed in response to CPF plasma collected during relapse, but not in response to plasma of hCtrls, or patients with SRNS, SSNS, and MN. The copresence of dimethylthiourea, a scavenger of ROS, abolished the aforementioned effects of CPF plasma. We provide a panel of invitro bioassays to measure podocyte injury and predict the presence of CPFs in plasma of patients with nephrotic syndrome (NS), providing a new framework for monitoring CPF activity that may contribute to future NS diagnostics or used for disease monitoring purposes. Moreover, our findings suggest that the inhibition of ROS formation or facilitating rapid ROS scavenging may exert beneficial effects in patients with CPFs.

Selenocystine induces oxidative-mediated DNA damage via impairing homologous recombination repair of DNA double-strand breaks in human hepatoma cells

Selenocystine (SeC) has been identified as a novel compound with broad-spectrum anticancer activity. However, the effects of SeC on modifying DNA repair mechanism were less addressed. In this study, we demonstrated that SeC selectively induced cytotoxicity and genotoxicity against HepG2 hepatoma cell line. Comet assay revealed SeC-induced DNA damage in HepG2 cells, particularly in the form of DNA double strand breaks (DSBs), corroborated by the increase expression of the DSB marker, gamma-H2AX. We further demonstrated that SeC suppressed DNA homologous recombination repair, exacerbating DNA damage accumulation. Such effects on DNA damage and cell viability inhibition were alleviated by antioxidants, glutathione and Trolox, suggesting the involvement of reactive oxygen species (ROS). High levels of intracellular and mitochondrial ROS were detected in SeC-treated HepG2. In addition, SeC impaired the expression of antioxidant enzymes (superoxidase mutases and catalase), prompting the imbalance between antioxidant protection and excessive ROS formation and eliciting DSBs and cellular death. Decreased procaspase-3, 7, and 9 and Bcl-2 proteins and an increased Bax/Bcl-2 ratio, were observed after SeC treatment, but could be reversed by Torlox, confirming the action of SeC on ROS-induced apoptosis. In vivo, the xenograft tumor model of HepG2 cells validated the inhibition of SeC on tumor growth, and the induction of DSBs and apoptosis.In summary, SeC has the capability to induce ROS-dependent DNA damage and impeded DBS repair in HepG2 cells. Thus, SeC holds great promise as a therapeutic or adjuvant agent targeting DNA repair for cancer treatment.

Anti-Inflammatory Effects of the Iron Chelator, DIBI, in Experimental Acute Lung Injury.

Iron plays a critical role in the immune response to inflammation and infection due to its role in the catalysis of reactive oxygen species (ROS) through the Haber-Weiss and Fenton reactions. However, ROS overproduction can be harmful and damage healthy cells. Therefore, iron chelation represents an innovative pharmacological approach to limit excess ROS formation and the related pro-inflammatory mediator cascades. The present study was designed to investigate the impact of the iron chelator, DIBI, in an experimental model of LPS-induced acute lung injury (ALI). DIBI was administered intraperitoneally in the early and later stages of lung inflammation as determined by histopathological evaluation. We found that lung tissues showed significant injury, as well as increased NF-B p65 activation and significantly elevated levels of various inflammatory mediators (LIX, CXCL2, CCL5, CXCL10, IL-1𝛽, IL-6) 4 h post ALI induction by LPS. Mice treated with DIBI (80 mg/kg) in the early stages (0 to 2 h) after LPS administration demonstrated a significant reduction of the histopathological damage score, reduced levels of NF-B p65 activation, and reduced levels of inflammatory mediators. Intravital microscopy of the pulmonary microcirculation also showed a reduced number of adhering leukocytes and improved capillary perfusion with DIBI administration. Our findings support the conclusion that the iron chelator, DIBI, has beneficial anti-inflammatory effects in experimental ALI.

Ethylene augments root hypoxia tolerance via growth cessation and reactive oxygen species amelioration.

Flooded plants experience impaired gas diffusion underwater, leading to oxygen deprivation (hypoxia). The volatile plant hormone ethylene is rapidly trapped in submerged plant cells and is instrumental for enhanced hypoxia acclimation. However, the precise mechanisms underpinning ethylene-enhanced hypoxia survival remain unclear. We studied the effect of ethylene pretreatment on hypoxia survival of Arabidopsis (Arabidopsis thaliana) primary root tips. Both hypoxia itself and re-oxygenation following hypoxia are highly damaging to root tip cells, and ethylene pretreatments reduced this damage. Ethylene pretreatment alone altered the abundance of transcripts and proteins involved in hypoxia responses, root growth, translation, and reactive oxygen species (ROS) homeostasis. Through imaging and manipulating ROS abundance in planta, we demonstrated that ethylene limited excessive ROS formation during hypoxia and subsequent re-oxygenation and improved oxidative stress survival in a PHYTOGLOBIN1-dependent manner. In addition, we showed that root growth cessation via ethylene and auxin occurred rapidly and that this quiescence behavior contributed to enhanced hypoxia tolerance. Collectively, our results show that the early flooding signal ethylene modulates a variety of processes that all contribute to hypoxia survival.

Silver Nanoparticles Exert Apoptotic Activity in Bladder Cancer 5637 Cells Through Alteration of Bax/Bcl-2 Genes Expression.

Bladder cancer is defined as a urinary tract malignancy that threatens men’s and women’s health. Due to the side effects of common chemotherapies, novel therapeutic strategies are necessary to overcome the issues concerning bladder cancer treatments. Nanotechnology has been suggested as a means to develop the next-generation objectives of cancer diagnosis and treatment among various novel therapies. Owing to the special characteristics that they can offer, silver nanoparticles (AgNPs) were investigated in this study to evaluate their apoptotic impact on bladder cancer 5637 cells. In this study, an MTT assay was conducted and appropriate concentrations of AgNPs were selected. Moreover, reactive oxygen species (ROS) production and apoptosis levels were determined using fluorimetric and Annexin/PI flow cytometry assays, respectively. Moreover, the activity of caspase 3,7, mRNA expression of Bax (Bcl-2-associated X) and Bcl-2 (B-cell lymphoma 2) were assessed based on colorimetric and qRT-PCR methods, respectively. The results indicated that AgNPs can significantly reduce the viability of 5637 cells in a dose-dependent mode as well as having the ability to elevate ROS production. Flow cytometry data showed that AgNPs lead to a remarkable increase in the apoptosis rate as compared with the control. Consistent with this, the induction of apoptosis was revealed by the overexpression of Bax, accompanied by a reduction in Bcl-2 expression compared to the control. Furthermore, AgNPs remarkably stimulated caspase 3,7 activation. In summary, AgNPs can mediate apoptosis in 5637 cells via excessive ROS formation, up-regulating Bax/Bcl-2 expression, and caspase 3,7 activation.

Cytoprotective Effects of the Tiger's Milk Mushroom Lignosus rhinocerotis (Agaricomycetes) Sclerotia against Oxidative Stress in PC12 Cells.

Lignosus rhinocerotis (Cooke) Ryvarden has been reported to possess numerous pharmacological effects. However, little is known about its potential role in mitigating the detrimental effects of oxidative stress. The present study investigated the cytoprotective effects of L. rhinocerotis extracts against hydrogen peroxide (H2O2)-induced oxidative stress of rat pheochromocytoma (PC12) cells. In the pre-treatment model, PC12 cells were pre-treated with aqueous (LRAQ) or ethanolic (LRET) extracts of L. rhinocerotis for 24 h, followed by 30 μM of H2O2 for 24 h. In the co-treatment model, the cells were incubated with LRAQ or LRET and H2O2 for 2 or 24 h to induce oxidative stress. Cell viability, intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), and apoptotic cells with activated caspase-3/7 were quantified. Additionally, LRET was separated into fractions by chromatographic methods prior to analysis by gas chromatography-mass spectrometry (GCMS). 320 μg/ml aqueous extract showed a significant cytoprotective effect of 70.0 ± 22.4% and 133.92 ± 8.8% in the pre-treatment and co-treatment models, respectively, compared to untreated H2O2-challenged cells. LRAQ also showed a reduction (p < 0.05) in the percentage of depolarized cells of 37.6 ± 0.6% at 640 ug/ml and 53.4 ± 4.5% at 320 ug/ml in the pre-treatment and co-treatment models, respectively, compared to untreated H2O2-challenged cells. LRAQ or LRET showed a reduction (p < 0.01) in caspase 3/7 activity compared to untreated H2O2-challenged cells in the co-treatment model. However, LRAQ or LRET did not reduce excessive ROS formation (p > 0.05). The cytoprotective effects could be attributed to the presence of fatty acids, phenols, phytosterols, and dicarboxylic acids. In conclusion, L. rhinocerotis extracts demonstrated cytoprotective effects against H2O2-induced oxidative stress in an in vitro model, contributing to the maintenance of cellular integrity through the regulation of mitochondrial function and apoptosis.

Reactive Oxygen Species-Based Biomaterials for Regenerative Medicine and Tissue Engineering Applications.

Reactive oxygen species (ROS), acting as essential mediators in biological system, play important roles in the physiologic and pathologic processes, including cellular signal transductions and cell homeostasis interference. Aberrant expression of ROS in tissue microenvironment can be caused by the internal/external stimuli and tissue injury, which may leads to an elevated level of oxidative stress, inflammatory response, and cellular damage as well as disruption in the tissue repair process. To prevent the formation of excess ROS around the injury site, advanced biomaterials can be remodeled or instructed to release their payloads in an injury microenvironment-responsive fashion to regulate the elevated levels of the ROS, which may also help downregulate the oxidative stress and promote tissue regeneration. A multitude of scaffolds and bioactive cues have been reported to promote the regeneration of damaged tissues based on the scavenging of free radicals and reactive species that confer high protection to the cellular activity and tissue function. In this review, we outline the underlying mechanism of ROS generation in the tissue microenvironment and present a comprehensive review of ROS-scavenging biomaterials for regenerative medicine and tissue engineering applications, including soft tissues regeneration, bone and cartilage repair as well as wound healing. Additionally, we highlight the strategies for the regulation of ROS by scaffold design and processing technology. Taken together, developing ROS-based biomaterials may not only help develop advanced platforms for improving injury microenvironment but also accelerate tissue regeneration.

A comparison between the function of Serendipita indica and Sinorhizobium meliloti in modulating the toxicity of zinc oxide nanoparticles in alfalfa (Medicago sativa L.).

Zinc oxide nanoparticles (ZnO-NPs) are among the most commonly used nano-fertilizers (NF). However, elevated levels of ZnO-NPs in soil may affect plant growth and development due to its potential toxicity when accumulated in large amounts in plant tissues. This research was conducted using an in situ rhizobox system with the aims of evaluating zinc uptake from nano-zinc oxide amended rhizosphere soil by alfalfa plant and the effect of plant growth-promoting microorganisms on alleviating the phytotoxicity of ZnO-NPs. Treatments included microbial inoculations (Sinorhizobium meliloti, Serendipita indica) and different ZnO-NP concentrations (0, 400, and 800 mg kg-1) with three replications. The results indicated that S. indica minimized the phytotoxicity of ZnO-NPs to alfalfa by enhancing growth rate and decreasing zinc (Zn) translocation from root to shoot. Compared with plants inoculated with S. meliloti, co-inoculation with S. indica increased the shoot dry weight by 18.33% and 8.05% at 400 and 800 mg kg-1 ZnO-NPs, respectively. However, at the highest level of ZnO-NPs (800 mg kg-1), root inoculation of S. indica and S. indica + S. meliloti decreased Zn translocation factor by 60.2% and 44.3% compared to S. meliloti, respectively. Furthermore, a distinct relation between tolerance of S. indica-colonized plant to ZnO-NPs and the ability of S. indica in inhibiting or retarding degradation of polyunsaturated lipids through prevention of excess reactive oxygen species formation was observed. Malondialdehyde content of inoculated plants with S. indica either alone or in combination with S. meliloti was significantly lower than non-inoculated plants (p< 0.01). Zn-induced oxidative stress was mitigated by S. indica through enhanced activities of catalase and peroxidase enzymes. The findings of the present study indicate the potential use of endophytes fungus S. indica for ensuring food safety and security, and human health in heavy metal-polluted soil by reducing the phytoavailability of heavy metals in the aerial parts of the host plants.

Abstract IA-023: The role of sirtuins in radiation-induced cardiac dysfunction

Abstract Currently there is no way to reliably predict who is at higher or lower risk of cardiac toxicity from radiation, and the critical factors that alter radiation-induced heart disease are not completely clear. The heart produces and uses the most energy of all organs, with &amp;gt;90% of its energy produced via mitochondrial respiration. To maintain this energy output, ~30% of the heart volume is made up of mitochondria in cardiomyocytes. Such a high metabolic rate produces increased levels of reactive oxygen species (ROS), which have the potential to cause serious oxidative damage to the heart. Antioxidant enzymes such as superoxide dysmutases (SODs), catalase, and glutathione peroxidase can help to protect against ROS-mediated damage by converting superoxide to hydrogen peroxidase, and then hydrogen peroxide to water. Oxidative stressors, including therapeutic radiation therapy, have been shown to lead to long-term effects on mitochondrial function, as measured by excess formation of ROS including superoxide, mitochondrial-related gene expression, and altered mitochondrial morphology and functions such as mitochondrial respiration, pyruvate metabolism, and ion and lipid transport. While a potential link between aging-related signaling pathways, metabolic homeostasis, and radiation-induced normal tissue damage has recently been suggested, rigorous mechanistic data to support this intriguing idea has been limited. Mitochondrial detoxification pathways, which are dysregulated in normal tissues by radiation, lead to increased ROS levels and the disruption of mitochondrial reparative pathways. SIRT3 is one of three mitochondrial-located sirtuin proteins. SIRT3 is the primary deacetylase of mitochondrial proteins, and its deacetylase activity plays a key role in maintaining mitochondrial energy metabolism equilibrium and defending against cellular damage that occurs with aging. Lysine acetylation is an important post-translational modification that can regulate the function of mitochondrial proteins. The acetylation status of key mitochondrial detoxification proteins, which are Sirt3 deacetylation targets, may be dysregulated in normal tissue following radiation exposure. Loss of SIRT3 can dysregulate mitochondrial detoxification and metabolism, leading to the accumulation of cellular damage. Sirt3 KO mice demonstrate enhanced mitochondrial dysfunction, and Sirt3 KO mice exhibit enhanced doxorubicin- and aortic constriction-induced cardiac hypertrophy. In addition, Sirt3 KO MEFs and livers are more sensitive to radiation and exhibit increased mitochondrial superoxide levels. However, the role of sirtuins in radiation-induced cardiac injury has not been examined. Here we review data on the potential role of sirtuins, and in particular Sirt3, on radiation-induced cardiac function. Citation Format: Carmen Bergom. The role of sirtuins in radiation-induced cardiac dysfunction [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-023.

Oxidative stress factors in Parkinson's disease.

Parkinson’s disease (PD) is the second most common cause of neurodegeneration. Over the last two decades, various hypotheses have been proposed to explain the etiology of PD. Among these is the oxidant-antioxidant theory, which asserts that local and systemic oxidative damage triggered by reactive oxygen species and other free radicals may promote dopaminergic neuron degeneration. Excessive reactive oxygen species formation, one of the underlying causes of pathology in the course of PD has been evidenced by various studies showing that oxidized macromolecules including lipids, proteins, and nucleic acids accumulate in brain tissues of PD patients. DNA oxidation may produce various lesions in the course of PD. Mutations incurred as a result of DNA oxidation may further enhance reactive oxygen species production in the brains of PD patients, exacerbating neuronal loss due to defects in the mitochondrial electron transport chain, antioxidant depletion, and exposure to toxic oxidized dopamine. The protein products of SNCA, PRKN, PINK1, DJ1, and LRRK2 genes are associated with disrupted oxidoreductive homeostasis in PD. SNCA is the first gene linked with familial PD and is currently known to be affected by six mutations correlated with the disorder: A53T, A30P, E46K, G51D, H50Q and A53E. PRKN encodes Parkin, an E3 ubiquitin ligase which mediates the proteasome degradation of redundant and disordered proteins such as glycosylated α-synuclein. Over 100 mutations have been found among the 12 exons of PRKN. PINK1, a mitochondrial kinase highly expressed in the brain, may undergo loss of function mutations which constitute approximately 1–8% of early onset PD cases. More than 50 PD-promoting mutations have been found in PINK1. Mutations in DJ-1, a neuroprotective protein, are a rare cause of early onset PD and constitute only 1% of cases. Around 20 mutations have been found in DJ1 among PD patients thus far. Mutations in the LRRK2 gene are the most common known cause of familial autosomal dominant PD and sporadic PD. Treatment of PD patients, especially in the advanced stages of the disease, is very difficult. The first step in managing progressive PD is to optimize dopaminergic therapy by increasing the doses of dopamine agonists and L-dopa. The next step is the introduction of advanced therapies, such as deep brain stimulation. Genetic factors may influence the response to L-dopa and deep brain stimulation therapy and the regulation of oxidative stress. Consequently, research into minimally invasive surgical interventions, as well as therapies that target the underlying etiology of PD is warranted.

Hyperoside from Z. bungeanum leaves restores insulin secretion and mitochondrial function by regulating pancreatic cellular redox status in diabetic mice

Type 2 diabetes mellitus (T2DM) is characterized by peripheral insulin resistance and insufficient insulin secretion caused by pancreatic β-cell dysfunction. Excessive production of reactive oxygen species (ROS) and activation of caspases in mitochondria inhibit insulin secretion and promote apoptosis of pancreatic β-cells. Studies have demonstrated that positive correlation between the consumption of flavonoid-rich diets and diabetes prevention. Zanthoxylum bungeanum leaves have been used as food for a long time and are rich in flavonoids with strong radical scavenging abilities. We and others have identified hyperoside as the major bioactive component of total flavonoids exacted from Zanthoxylum bungeanum leaves. We hypothesize that hyperoside from Z. bungeanum leaves (HZL) may prevent T2DM by inhibiting excessive ROS formation and reducing pancreatic β-cells apoptosis. In current study, HZL was administered to high fat diet and alloxan-induced diabetic mice, and appeared to significantly ameliorate the damage of glucose metabolism and insulin secretion as well as restore the structural integrity of pancreas, and inhibit β-cell apoptosis. Pancreatic antioxidant enzyme activities were also restored by HZL supplementation. In cultured MIN6 cells, which produce and secret insulin, HZL treatment restored insulin secretion through inhibiting the expression of TXNIP and lowering intracellular calcium concentration. These observations mechanistically linked the beneficial effects of HZL with the regulation on cellular redox status and mitochondrial function. Taken together, our findings suggest that HZL has protective effect on pancreatic β-cell function and may be a beneficial nutritional supplementation for prevention and adjuvant therapy of T2DM.

Semi-refined carrageenan promotes generation of reactive oxygen species in leukocytes of rats upon oral exposure but not in vitro.

To assess the ability of the common food additive E407a (semi-refined carrageenan) to enter leukocytes in vitro and generate reactive oxygen species (ROS) in leukocytes as awhole and granulocytes in particular, both during incubation and in experimental animals. ROS production was assessed in leukocytes incubated with E407afor 2 h at the final concentrations of 5 and 10 g/L using the dye 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA), as well as in cells isolated from rats orally exposed to E407a (140 mg/kg of weight) during 2weeks (n = 8) and control rats (n = 8), by flow cytometry. Carrageenan uptake by leukocytes was estimated by confocal microscopy using incubation of rhodamineB isothiocyanate-labelled carrageenan with leukocyte suspensions. Uptake of carrageenan by viable neutrophils, monocytes, and lymphocytes was confirmed. Oral administration of the food additive E407awas associated with excessive ROS formation by viable leukocytes (CD45+, 7‑aminoactinomycin D- cells) and especially in granulocytes. Unexpectedly, adirect impact of semi-refined carrageenan during incubation for 2 h did not affect ROS production in leukocytes, evidenced by statistically insignificant differences in mean fluorescence intensity values of 2',7'-dichlorofluorescein, which is aROS-sensitive product of intracellular H2DCFDA conversion. Oral intake of E407a and direct exposure of leukocyte suspensions to it decreased the viability of leukocytes. Food-grade carrageenan can enter leukocytes without affecting ROS generation as aresult of incubation for 2 h with leukocyte suspensions. On the contrary, oral exposure to E407a is accompanied by ROS overproduction by white blood cells, suggesting an indirect mechanism for the stimulation of ROS synthesis in vivo. E407a promotes cell death of leukocytes both in vivo and in vitro.

Regulation of Vascular Calcification by Reactive Oxygen Species.

Vascular calcification is the deposition of hydroxyapatite crystals in the medial or intimal layers of arteries that is usually associated with other pathological conditions including but not limited to chronic kidney disease, atherosclerosis and diabetes. Calcification is an active, cell-regulated process involving the phenotype transition of vascular smooth muscle cells (VSMCs) from contractile to osteoblast/chondrocyte-like cells. Diverse triggers and signal transduction pathways have been identified behind vascular calcification. In this review, we focus on the role of reactive oxygen species (ROS) in the osteochondrogenic phenotype switch of VSMCs and subsequent calcification. Vascular calcification is associated with elevated ROS production. Excessive ROS contribute to the activation of certain osteochondrogenic signal transduction pathways, thereby accelerating osteochondrogenic transdifferentiation of VSMCs. Inhibition of ROS production and ROS scavengers and activation of endogenous protective mechanisms are promising therapeutic approaches in the prevention of osteochondrogenic transdifferentiation of VSMCs and subsequent vascular calcification. The present review discusses the formation and actions of excess ROS in different experimental models of calcification, and the potential of ROS-lowering strategies in the prevention of this deleterious condition.