Oxidative Stress-induced Damage Research Articles

Gamma-glutamyl transferase levels are associated with the occurrence of post-stroke cognitive impairment: a multicenter cohort study

BackgroundGamma-glutamyl transferase (GGT) is involved in maintenance of physiological concentrations of glutathione in cells, and protects them from oxidative stress-induced damage. However, its role in post-stroke cognitive impairment (PSCI) remains unknown. Here, we investigated the effects of serum GGT on PSCI.MethodsWe conducted a prospective, multicenter cohort study. A total of 1, 957 participants with a minor ischemic stroke or transient ischemic attack whose baseline GGT levels were measured were enrolled from the Impairment of Cognition and Sleep (ICONS) study of the China National Stroke Registry-3 (CNSR-3). They were categorized into four groups according to quartiles of baseline GGT levels. Cognitive functions were assessed using the Montreal Cognitive Assessment (MoCA) approach. Multiple logistic regression models were performed to evaluate the relationship between GGT and PSCI at 3 months follow-up.ResultsAmong the 1957 participants, 671 (34.29%) patients suffered PSCI at 3 months follow-up. The highest GGT level quartile group exhibited a lower risk of PSCI in the fully adjusted model [OR (95% CI): 0.69 (0.50-0.96)], relative to the lowest group. Moreover, incorporation of GGT to the conventional model resulted in slight improvements in PSCI outcomes after 3 months (NRI: 12.00%; IDI: 0.30%).ConclusionsSerum GGT levels are inversely associated with the risk of PSCI, with extremely low levels being viable risk factors for PSCI.

Inhibition of TRPA1 Attenuates Oxidative Stress-induced Damage After Traumatic Brain Injury via the ERK/AKT Signaling Pathway

Neuron apoptosis is a feature of secondary injury after traumatic brain injury (TBI). Evidence implies that excess calcium (Ca2+) ions and reactive oxidative species (ROS) play critical roles in apoptosis. In reaction to increased ROS, the anti-oxidative master transcription factor, Transient receptor potential Ankyrin 1 (TRPA1) allows Ca2+ ions to enter cells. However, the effect of TBI on the expression of TRPA1 and the role of TRPA1 in TBI are unclear. In the present study, TBI in the mouse brain was simulated using the weight-drop model. The process of neuronal oxidative stress was simulated in HT22 neuronal cells by treatment with hydrogen peroxide. We found that TRPA1 was significantly upregulated in neurons at 24 h after TBI. Neuronal apoptosis was increased in the in vivo and in vitro models; however, this increase was reduced by the functional inhibition of TRPA1 in both models. After TBI, TRPA1 was upregulated via nuclear factor, erythroid 2 like 2 (Nrf2) in neurons. TRPA1-mediated neuronal apoptosis after TBI might be achieved in part through the CaMKII/AKT/ERK signaling pathway. To sum up, TBI-triggered TRPA1 upregulation in neurons is mediated by Nrf2 and the functional blockade of TRPA1 attenuates neuronal apoptosis and improves neuronal dysfunction, partially mediated through the activation of the calcium/calmodulin dependent protein kinase II (CaMKII) extracellular regulated kinase (ERK)/protein kinase B (AKT) signaling pathway. Our results suggest that functional blockade of TRPA1 might be a promising therapeutic intervention related to ROS and Nrf2 in TBI.

Neurotoxicity of anthracene and benz[a]anthracene involves oxidative stress-induced neuronal damage, cholinergic dysfunction and disruption of monoaminergic and purinergic enzymes.

In this study, the modulatory effects of anthracene (ANT) and benz[a]anthracene (BEN) on biochemical markers associated with neurodegeneration were assessed in mouse hippocampal neuronal cells (HT-22). Neuronal cells were cultured and exposed to ANT and BEN (25-125µM) for 5days, and the cell viability was determined via MTT assay. Morphological characteristics of the cells were assessed using a compound microscope. Biochemical parameters such as acetylcholinesterase (AChE), monoamine oxidase (MAO) and adenosine deaminase (ADA) activities as well as oxidative stress biomarkers (catalase [CAT], glutathione -S- transferase [GST] activities and Glutathione [GSH] levels) and nitric oxide [NO] levels were assessed after cells were treated with ANT and BEN for two days. The results showed that cell viability reduced with an increase in exposure time. After the fifth day of treatment, BEN and ANT (125µM) reduced percentage viability to 41 and 38.1%, respectively. Light micrographs showed shrinkage of cells, neuronal injury and cell death in cells treated with higher concentrations of BEN and ANT (50 and 125µM). Furthermore, AChE and MAO activities reduced significantly after treatment for 48h with ANT and BEN. A significant decrease in CAT and GST activities and low GSH levels were observed after treatment with BEN and ANT. However, both polycyclic aromatic hydrocarbons caused a significant increase in ADA activity and NO levels. These results suggest that ANT and BEN may induce neurodegeneration in neuronal cells via oxidative stress-induced-neuronal injury, disruption of cholinergic, monoaminergic and purinergic transmission, and increased nitric oxide levels.

Systemic Administration of Tempol, a Superoxide Dismutase Mimetic, Augments Upper Airway Muscle Activity in Obese Zucker Rats.

Obstructive sleep apnea (OSA) is characterized by repetitive partial/complete collapse of the pharynx during sleep, which results in apnea/hypopnea leading to arterial oxygen desaturations and arousals. Repetitive apnea/hypopnea-arousal episodes cause hypoxia/reoxygenation cycles, which increase free radical generation and oxidative stress that cause motor/sensory nerve impairments and muscle damage. We hypothesize that antioxidants may protect and/or reverse from oxidative stress-induced damage in OSA patients. To understand the acute protective effects of antioxidants on respiratory muscles, we studied the systemic effects of a membrane permeable superoxide dismutase mimetic, Tempol, on genioglossus (EMGGG) and diaphragmatic (EMGDIA) electro-myographic activities, hypoglossal motoneuron (HMN) nerve activity and cardiorespiratory parameters (mean arterial blood pressure, heart rate) in adult isoflurane-anesthetized obese Zucker rats (OZR) and age-matched lean Zucker rats (LZR). Tempol dose-dependently (1–100 mg/kg) increased EMGGG without changing EMGDIA in OZR and LZR. Tempol increased respiratory rate and tidal volume in OZR and LZR. Tempol (1–25 mg/kg) dose-dependently increased HMN nerve activity in healthy Sprague Dawley rats. Tempol (100 mg/kg) increased EMGGG output by 189% in OZR and 163% in LZR. With respect to mechanisms of effect, Tempol (100 mg/kg) did not augment EMGGG after bilateral HMN transection in Sprague Dawley rats. Although future studies are warranted, available data suggest that in addition to its antioxidant and antihypertensive properties, Tempol can selectively augment EMGGG through modulating HMN and this effect may prevent collapsibility and/or improve stability of the upper airway pharyngeal dilator muscles during episodes of partial and/or complete collapse of the upper airway in OSA human subjects.

REV-ERBα regulates age-related and oxidative stress-induced degeneration in retinal pigment epithelium via NRF2

Retinal pigment epithelium (RPE) dysfunction and atrophy occur in dry age-related macular degeneration (AMD), often leading to photoreceptor degeneration and vision loss. Accumulated oxidative stress during aging contributes to RPE dysfunction and degeneration. Here we show that the nuclear receptor REV-ERBα, a redox sensitive transcription factor, protects RPE from age-related degeneration and oxidative stress-induced damage. Genetic deficiency of REV-ERBα leads to accumulated oxidative stress, dysfunction and degeneration of RPE, and AMD-like ocular pathologies in aging mice. Loss of REV-ERBα exacerbates chemical-induced RPE damage, and pharmacological activation of REV-ERBα protects RPE from oxidative damage both in vivo and in vitro. REV-ERBα directly regulates transcription of nuclear factor erythroid 2-related factor 2 (NRF2) and its downstream antioxidant enzymes superoxide dismutase 1 (SOD1) and catalase to counter oxidative damage. Moreover, aged mice with RPE specific knockout of REV-ERBα also exhibit accumulated oxidative stress and fundus and RPE pathologies. Together, our results suggest that REV-ERBα is a novel intrinsic protector of the RPE against age-dependent oxidative stress and a new molecular target for developing potential therapies to treat age-related retinal degeneration.

Therapeutic Interventions to Mitigate Mitochondrial Dysfunction and Oxidative Stress-Induced Damage in Patients with Bipolar Disorder.

Bipolar disorder (BD) is characterized by mood changes, including recurrent manic, hypomanic, and depressive episodes, which may involve mixed symptoms. Despite the progress in neurobiological research, the pathophysiology of BD has not been extensively described to date. Progress in the understanding of the neurobiology driving BD could help facilitate the discovery of therapeutic targets and biomarkers for its early detection. Oxidative stress (OS), which damages biomolecules and causes mitochondrial and dopamine system dysfunctions, is a persistent finding in patients with BD. Inflammation and immune dysfunction might also play a role in BD pathophysiology. Specific nutrient supplements (nutraceuticals) may target neurobiological pathways suggested to be perturbed in BD, such as inflammation, mitochondrial dysfunction, and OS. Consequently, nutraceuticals may be used in the adjunctive treatment of BD. This paper summarizes the possible roles of OS, mitochondrial dysfunction, and immune system dysregulation in the onset of BD. It then discusses OS-mitigating strategies that may serve as therapeutic interventions for BD. It also analyzes the relationship between diet and BD as well as the use of nutritional interventions in the treatment of BD. In addition, it addresses the use of lithium therapy; novel antipsychotic agents, including clozapine, olanzapine, risperidone, cariprazine, and quetiapine; and anti-inflammatory agents to treat BD. Furthermore, it reviews the efficacy of the most used therapies for BD, such as cognitive–behavioral therapy, bright light therapy, imagery-focused cognitive therapy, and electroconvulsive therapy. A better understanding of the roles of OS, mitochondrial dysfunction, and inflammation in the pathogenesis of bipolar disorder, along with a stronger elucidation of the therapeutic functions of antioxidants, antipsychotics, anti-inflammatory agents, lithium therapy, and light therapies, may lead to improved strategies for the treatment and prevention of bipolar disorder.

Cu/Zn Superoxide Dismutase and Catalase of Yangtze Sturgeon, Acipenser dabryanus: Molecular Cloning, Tissue Distribution and Response to Fasting and Refeeding

Superoxide dismutase and catalase are two major antioxidant enzymes in the fish antioxidant defense system, which can remove excess reactive oxygen species and protect fish from stress-induced oxidative damage. The present study aimed to clone the sequences of Yangtze sturgeon, Acipenser dabryanus, Cu/Zn superoxide dismutase (AdCu/Zn-SOD) and catalase (AdCAT), and to explore changes of gene expression in the liver and intestine during fasting and refeeding. A total of 120 fish were exposed to four fasting and refeeding protocols (fasting for 0, 3, 7, or 14 d and then refeeding for 14 d). The coding sequences of AdCu/Zn-SOD and AdCAT encoded 155 and 526 amino acid proteins, respectively, both of which were expressed mainly in the liver. During fasting, when compared to the control group, liver AdCu/Zn-SOD expression was significantly higher in the 3- and 14-d groups, whereas its intestinal expression increased significantly only in the 7-d group. Liver AdCAT expression increased significantly in the 3-, 7-, and 14-d groups. During refeeding, liver AdCu/Zn-SOD expression increased significantly in the 3-, 7-, and 14-d groups compared with those in the control group. Similarly, intestinal AdCu/Zn-SOD expression increased significantly in the 3- and 7-d groups. Moreover, intestinal AdCAT expression was significantly higher in the 3-d group than in the control group, but decreased significantly in the 14-d group. Our findings indicated that AdCu/Zn-SOD and AdCAT play important roles in protecting fish against starvation-induced oxidative stress. Yangtze sturgeon exhibited the potential to adapt to a starvation and refeeding regime.

Sodium Butyrate Ameliorates Oxidative Stress-Induced Intestinal Epithelium Barrier Injury and Mitochondrial Damage through AMPK-Mitophagy Pathway.

Sodium butyrate has gained increasing attention for its vast beneficial effects. However, whether sodium butyrate could alleviate oxidative stress-induced intestinal dysfunction and mitochondrial damage of piglets and its underlying mechanism remains unclear. The present study used a hydrogen peroxide- (H2O2-) induced oxidative stress model to study whether sodium butyrate could alleviate oxidative stress, intestinal epithelium injury, and mitochondrial dysfunction of porcine intestinal epithelial cells (IPEC-J2) in AMPK-mitophagy-dependent pathway. The results indicated that sodium butyrate alleviated the H2O2-induced oxidative stress, decreased the level of reactive oxygen species (ROS), increased mitochondrial membrane potential (MMP), mitochondrial DNA (mtDNA), and mRNA expression of genes related to mitochondrial function, and inhibited the release of mitochondrial cytochrome c (Cyt c). Sodium butyrate reduced the protein expression of recombinant NLR family, pyrin domain-containing protein 3 (NLRP3) and fluorescein isothiocyanate dextran 4 kDa (FD4) permeability and increased transepithelial resistance (TER) and the protein expression of tight junction. Sodium butyrate increased the expression of light-chain-associated protein B (LC3B) and Beclin-1, reduced the expression of P62, and enhanced mitophagy. However, the use of AMPK inhibitor or mitophagy inhibitor weakened the protective effect of sodium butyrate on mitochondrial function and intestinal epithelium barrier function and suppressed the induction effect of sodium butyrate on mitophagy. In addition, we also found that after interference with AMPKα, the protective effect of sodium butyrate on IPEC-J2 cells treated with H2O2 was suppressed, indicating that AMPKα is necessary for sodium butyrate to exert its protective effect. In summary, these results revealed that sodium butyrate induced mitophagy by activating AMPK, thereby alleviating oxidative stress, intestinal epithelium barrier injury, and mitochondrial dysfunction induced by H2O2.

Inhibition of thioredoxin-interacting protein may enhance the therapeutic effect of dehydrocostus lactone in cardiomyocytes under doxorubicin stimulation via the inhibition of the inflammatory response.

Heart failure (HF) is the leading cause of death around the world, the mortality caused by HF is growing rapidly, and has become a great threaten to both public health and economic growth. Dehydrocostus lactone (DHE) is the active constituent of Saussurea lappa and is widely used in traditional Chinese medicine for its multiple biological functions, including anti-inflammatory, antioxidant and anti-cancer. To the best of our knowledge, DHE's effect on HF has not been clarified. Thioredoxin-interacting protein (TXNIP) regulates the process of oxidative stress and inflammation and leads to an increase in oxidative stress via oxidization of thioredoxin, TXNIP promotes the activation of the immune response by its binding with the NOD-like receptor protein 3 inflammasome. An MTT assay revealed that the overexpression or inhibition of TXNIP markedly decreased or significantly increased the proliferation of H9c2 cells, respectively. Through reverse transcription-quantitative PCR (RT-qPCR) and western blotting, it was determined that the expression of proinflammatory cytokines was significantly decreased with the increased expression of anti-inflammatory cytokines in a TXNIP knockout model. Further study utilizing RT-qPCR and western blotting demonstrated that these effects may be mediated by the nuclear factor erythroid 2-related factor 2/heme oxygenase-1/NF-κB signaling pathway. In conclusion, TXNIP inhibition may promote the therapeutic effect of DHE on oxidative stress-induced damage.

Orally administered titanium carbide nanosheets as anti-inflammatory therapy for colitis.

Rationale: Oxidative stress, resulting from excessive reactive oxygen species (ROS), plays an important role in the initiation and progression of inflammatory bowel disease (IBD). Therefore, developing novel strategies to target the disease location and treat inflammation is urgently needed.Methods: Herein, we designed and developed a novel and effective antioxidant orally-administered nanoplatform based on simulated gastric fluid (SGF)-stabilized titanium carbide MXene nanosheets (Ti3C2 NSs) with excellent biosafety and multiple ROS-scavenging abilities for IBD therapy.Results: This broad-spectrum and efficient ROS scavenging performance was mainly relied on the strong reducibility of Ti-C bound. Intracellular ROS levels confirmed that Ti3C2 NSs could efficiently eliminate excess ROS against oxidative stress-induced cell damage. Following oral administration, negatively-charged Ti3C2 NSs specifically adsorbed onto the positively-charged inflamed colon tissue via electrostatic interaction, leading to efficient therapy of dextran sulfate sodium salt (DSS)-induced colitis. The therapeutic mechanism mainly attributed to decreased ROS levels and pro-inflammatory cytokine secretion, and increased M2-phenotype macrophage infiltration and anti-inflammatory cytokine secretion, efficiently inhibiting inflammation and alleviating colitis symptoms. Due to their excellent ROS-scavenging performance, Ti3C2-based woundplast also promoted skin wound healing and functional vessel formation.Conclusions: Our study introduces redox-mediated antioxidant MXene nanoplatform as a novel type of orally administered nanoagents for treating IBD and other inflammatory diseases of the digestive tract.

Protective effects of ginsenoside CK against oxidative stress-induced neuronal damage, assessed with 1H-NMR-based metabolomics

Oxidative stress is an important pathogenic mechanism in degenerative diseases such as Alzheimer’s disease. Although ginsenoside compound K (CK) is protective against neuronal oxidative damage, the underlying mechanism remains to be understood. In this study, the protective effects of ginsenoside CK against oxidative stress damage induced by hydrogen peroxide in HT22 cells were investigated with 1H nuclear magnetic resonance (1H-NMR)-based metabolomics. The optimal CK concentration for decreasing oxidative stress damage in nerves was determined with MTT assays. CK (8 μM) significantly increased the HT22 cell survival rate after the model was established. Cell lysates were subjected to 1H-NMR metabolomics, western blotting, and ATP assays for verification. Metabolic perturbation occurred in HT22 cells in the model group but not the control group. Twenty biomarkers were identified and used to analyze metabolic pathways. CK reversed metabolic changes in HT22 cells by altering taurine, glutamate, glycine, and glutathione metabolism. Subsequently, CK increased ATP content and the expression of components of the PI3K/AKT signaling pathway in HT22 cells. These findings demonstrated that CK prevents oxidative stress damage and protects nerves by regulating energy-metabolism pathways, such as those of taurine, glutamate, and other amino acids, thus providing a rationale for the use of CK in Alzheimer’s disease treatment.

Protective Effect of Phragmitis Rhizoma against Oxidative Stress-induced DNA Damage and Apoptosis in Chang Liver Cells

Objectives: Phragmitis Rhizoma is the fresh or dried rhizome of Phragmites communis Trin., which has been prescribed in traditional Korean medicine to relieve fever and vomiting and to nourish the body fluids. Recently, the protective effect of Phragmitis Rhizoma extract or its components on myelotoxicity and inflammatory responses have been reported, but no study has yet been conducted on oxidative stress.Methods: The present study investigated whether an ethanol extract of Phragmitis Rhizoma (PR) could protect against cellular damage induced by oxidative stress in Chang liver cells.Results: Pretreatment with PR significantly suppressed the hydrogen peroxide (H2O2)-induced reduction of Chang cell viability and generation of reactive oxygen species (ROS), thereby deferring apoptosis. PR also markedly inhibited H2O2-induced comet tail formation and phospho-γH2AX expression, suggesting that PR protected against oxidative stress–mediated DNA damage. PR also effectively prevented the inhibition of ATP synthesis in H2O2-treated Chang cells by inhibiting the loss of mitochondrial membrane potential, indicating that PR maintains energy metabolism through preservation of mitochondrial function while eliminating ROS generated by H2O2. Immunoblotting results indicated that PR attenuated the H2O2-induced downregulation of Bcl-2 and upregulation of Bax expression.Conclusions: PR protects against oxidative injury in Chang liver cells by regulating energy homeostasis via ROS generation blockade, which is at least partly mediated through inactivation of the mitochondria-mediated apoptosis pathway.

Acacia catechu Willd. Extract Protects Neuronal Cells from Oxidative Stress-Induced Damage.

Oxidative stress (OS) and the resulting reactive oxygen species (ROS) generation and inflammation play a pivotal role in the neuronal loss occurring during the onset of neurodegenerative diseases. Therefore, promising future drugs that would prevent or slow down the progression of neurodegeneration should possess potent radical-scavenging activity. Acacia catechu Willd. heartwood extract (AC), already characterized for its high catechin content, is endowed with antioxidant properties. The aim of the present study was to assess AC neuroprotection in both human neuroblastoma SH-SY5Y cells and rat brain slices treated with hydrogen peroxide. In SH-SY5Y cells, AC prevented a decrease in viability, as well as an increase in sub-diploid-, DAPI positive cells, reduced ROS formation, and recovered the mitochondrial potential and caspase-3 activation. AC related neuroprotective effects also occurred in rat brain slices as a reversal prevention in the expression of the main proteins involved in apoptosis and signalling pathways related to calcium homeostasis following OS-mediated injury. Additionally, unbiased quantitative mass spectrometry allowed for assessing that AC partially prevented the hydrogen peroxide-induced altered proteome, including proteins belonging to the synaptic vesicle fusion apparatus. In conclusion, the present results suggest the possibility of AC as a nutraceutical useful in preventing neurodegenerative diseases.

Cold acclimation alleviates cold stress-induced PSII inhibition and oxidative damage in tobacco leaves

ABSTRACT This study aimed to explore how cold acclimation (CA) modulates cold stress in tobacco leaves and reveal the relationship between CA and cold stress resistance, and the mechanism of CA-induced plant resistance to cold stress. This study examined the effects of CA treatment (at 8–10℃ for 2 d) on the cold tolerance of tobacco leaves under 4°C cold stress treatment using seedlings without CA treatment as the control (NA). In both CA and NA leaves, cold stress treatment resulted in a decrease in maximum photochemical efficiency of PSII (F v /F m), increase in relative variable fluorescence (V J) at 2 ms on the standardized OJIP curve, inhibition of PSII activity, and impairment of electron transfer on the acceptor side. Besides increasing the malondialdehyde (MDA) content and electrolyte leakage rate, the cold stress exacerbated the degree of membrane peroxidation. The CA treatment also induced the accumulation of reactive oxygen species (ROS), including superoxide anion (O2·−) and H2O2, and increased the activities of antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbic acid peroxidase (APX). The CA treatment also enhanced the accumulation of soluble sugar (SS) and soluble protein (SP), cyclic electron flow (CEF), and the proportion of regulatory energy dissipation Y(NPQ). Moreover, CA+ cold stress treatment significantly reduced CEF and Y(NPQ) in tobacco leaves than under NA+ cold stress treatment, thus significantly alleviating the degree of PSII photoinhibition. In conclusion, CA treatment significantly alleviated PSII photoinhibition and oxidative damage in tobacco leaves under cold stress treatment. Improvement in cold resistance of tobacco leaves is associated with the induction of antioxidant enzyme activity, accumulation of osmoregulation substances, and initiation of photoprotective mechanisms.

Siderophore-Mediated Iron Acquisition Plays a Critical Role in Biofilm Formation and Survival of Staphylococcus epidermidis Within the Host.

Iron acquisition through siderophores, a class of small, potent iron-chelating organic molecules, is a widely spread strategy among pathogens to survive in the iron-restricted environment found in the host. Although these molecules have been implicated in the pathogenesis of several species, there is currently no comprehensive study addressing siderophore production in Staphylococcus epidermidis. Staphylococcus epidermidis is an innocuous skin commensal bacterium. The species, though, has emerged as a leading cause of implant-associated infections, significantly supported by an inherent ability to form biofilms. The process of adaptation from skin niche environments to the hostile conditions during invasion is yet not fully understood. Herein, we addressed the possible role of siderophore production in S. epidermidis virulence. We first identified and deleted a siderophore homolog locus, sfaABCD, and provided evidence for its involvement in iron acquisition. Our findings further suggested the involvement of siderophores in the protection against oxidative stress-induced damage and demonstrated the in vivo relevance of a siderophore-mediated iron acquisition during S. epidermidis infections. Conclusively, this study addressed, for the first time in this species, the underlying mechanisms of siderophore production, highlighting the importance of a siderophore-mediated iron acquisition under host relevant conditions and, most importantly, its contribution to survival within the host.

Mitochondriotropic antioxidant based on caffeic acid AntiOxCIN4 activates Nrf2-dependent antioxidant defenses and quality control mechanisms to antagonize oxidative stress-induced cell damage

Mitochondria are key organelles involved in cellular survival, differentiation, and death induction. In this regard, mitochondrial morphology and/or function alterations are involved in stress-induced adaptive pathways, priming mitochondria for mitophagy or apoptosis induction. We have previously shown that the mitochondriotropic antioxidant AntiOxCIN4 (100 μM; 48 h) presented significant cytoprotective effect without affecting the viability of human hepatoma-derived (HepG2) cells. Moreover, AntiOxCIN4 (12.5 μM; 72 h) caused a mild increase of reactive oxygen species (ROS) levels without toxicity to primary human skin fibroblasts (PHSF). As Nrf2 is a master regulator of the oxidative stress response inducing antioxidant-encoding gene expression, we hypothesized that AntiOxCIN4 could increase the resistance of human hepatoma-derived HepG2 to oxidative stress by Nrf2-dependent mechanisms, in a process mediated by mitochondrial ROS (mtROS). Here we showed that after an initial decrease in oxygen consumption paralleled by a moderate increase in superoxide anion levels, AntiOxCIN4 led to a time-dependent Nrf2 translocation to the nucleus. This was followed later by a 1.5-fold increase in basal respiration and a 1.2-fold increase in extracellular acidification. AntiOxCIN4 treatment enhanced mitochondrial quality by triggering the clearance of defective organelles by autophagy and/or mitophagy, coupled with increased mitochondrial biogenesis. AntiOxCIN4 also up-regulated the cellular antioxidant defense system. AntiOxCIN4 seems to have the ability to maintain hepatocyte redox homeostasis, regulating the electrophilic/nucleophilic tone, and preserve cellular physiological functions. The obtained data open a new avenue to explore the effects of AntiOxCIN4 in the context of preserving hepatic mitochondrial function in disorders, such as NASH/NAFLD and type II diabetes.

The Protective Effect of Carotenoids, Polyphenols, and Estradiol on Dermal Fibroblasts under Oxidative Stress.

Skin ageing is influenced by several factors including environmental exposure and hormonal changes. Reactive oxygen species (ROS), which mediate many of the effects of these factors, induce inflammatory processes in the skin and increase the production of matrix metalloproteinases (MMPs) in dermal fibroblasts, which leads to collagen degradation. Several studies have shown the protective role of estrogens and a diet rich in fruits and vegetables on skin physiology. Previous studies have shown that dietary carotenoids and polyphenols activate the cell’s antioxidant defense system by increasing antioxidant response element/Nrf2 (ARE/Nrf2) transcriptional activity and reducing the inflammatory response. The aim of the current study was to examine the protective effect of such dietary-derived compounds and estradiol on dermal fibroblasts under oxidative stress induced by H2O2. Human dermal fibroblasts were used to study the effect of H2O2 on cell number and apoptosis, MMP-1, and pro-collagen secretion as markers of skin damage. Treatment of cells with H2O2 led to cell death, increased secretion of MMP-1, and decreased pro-collagen secretion. Pre-treatment with tomato and rosemary extracts, and with estradiol, reversed the effects of the oxidative stress. This was associated with a reduction in intracellular ROS levels, probably through the measured increased activity of ARE/Nrf2. Conclusions: This study indicates that carotenoids, polyphenols, and estradiol protect dermal fibroblasts from oxidative stress-induced damage through a reduction in ROS levels.

CCN2 Aggravates the Immediate Oxidative Stress–DNA Damage Response following Renal Ischemia–Reperfusion Injury

AKI, due to the fact of altered oxygen supply after kidney transplantation, is characterized by renal ischemia–reperfusion injury (IRI). Recent data suggest that AKI to CKD progression may be driven by cellular senescence evolving from prolonged DNA damage response (DDR) following oxidative stress. Cellular communication factor 2 (CCN2, formerly called CTGF) is a major contributor to CKD development and was found to aggravate DNA damage and the subsequent DDR–cellular senescence–fibrosis sequence following renal IRI. We therefore investigated the impact of CCN2 inhibition on oxidative stress and DDR in vivo and in vitro. Four hours after reperfusion, full transcriptome RNA sequencing of mouse IRI kidneys revealed CCN2-dependent enrichment of several signaling pathways, reflecting a different immediate stress response to IRI. Furthermore, decreased staining for γH2AX and p-p53 indicated reduced DNA damage and DDR in tubular epithelial cells of CCN2 knockout (KO) mice. Three days after IRI, DNA damage and DDR were still reduced in CCN2 KO, and this was associated with reduced oxidative stress, marked by lower lipid peroxidation, protein nitrosylation, and kidney expression levels of Nrf2 target genes (i.e., HMOX1 and NQO1). Finally, silencing of CCN2 alleviated DDR and lipid peroxidation induced by anoxia-reoxygenation injury in cultured PTECs. Together, our observations suggest that CCN2 inhibition might mitigate AKI by reducing oxidative stress-induced DNA damage and the subsequent DDR. Thus, targeting CCN2 might help to limit post-IRI AKI.

AMPK-PINK1/Parkin Mediated Mitophagy Is Necessary for Alleviating Oxidative Stress-Induced Intestinal Epithelial Barrier Damage and Mitochondrial Energy Metabolism Dysfunction in IPEC-J2.

The imbalance of redox biology and oxidative stress leads to intestinal barrier injury and mitophagy. However, much uncertainty still exists about the role of mitophagy in oxidative stress and intestinal function. Here, we showed the effects of hydrogen peroxide (H2O2)-induced oxidative stress on intestinal epithelial cell oxidation balance, intestinal barrier function and mitochondrial energy metabolism and its underlying mechanism. In this study, we found that H2O2-induced oxidative stress activated adenosine monophosphate-activated protein kinase (AMPK) and enhanced mitophagy in intestinal porcine epithelial cells (IPEC-J2). While compound C (AMPK inhibitor) and mdivi-1 (mitophagy inhibitor) significantly reduced the activity of superoxide dismutase (SOD) and increased mitochondrial reactive oxygen species (ROS) levels in H2O2 treated cells. Moreover, compound C and mdivi-1 significantly reduced the trans-epithelium electrical resistant (TER) and increased the fluorescein isothiocyanate-dextran (FD4) flux in H2O2 treated IPEC-J2. Furthermore, compound C and mdivi-1 significantly reduced the activity of mitochondrial complex II. Seahorse XF96 data showed that compound C + mdivi-1+ H2O2 treatment significantly reduced maximum respiratory oxygen consumption and spare respiratory capacity. Additionally, compound C or mdivi-1 treatment reduced the formation of mitochondrial autophagosomes. These results unveiled that AMPK and PINK1/Parkin mediated mitophagy is necessary for alleviating oxidative stress induced intestinal epithelial barrier damage and mitochondrial energy metabolism dysfunction in IPEC-J2.

JAK Inhibition Prevents DNA Damage and Apoptosis in Testicular Ischemia-Reperfusion Injury via Modulation of the ATM/ATR/Chk Pathway.

Testicular ischemia reperfusion injury (tIRI) causes oxidative stress-induced DNA damage leading to germ cell apoptosis (GCA). The aim of the study is to establish a direct link between JAK2 activation and the DNA damage response (DDR) signaling pathways and their role in tIRI-induced GCA using AG490, a JAK2 specific inhibitor. Male Sprague Dawley rats (n = 36) were divided into three groups: sham, unilateral tIRI and tIRI + AG490 (40 mg/kg). During tIRI, augmentation in the phosphorylation levels of the JAK2/STAT1/STAT3 was measured by immunohistochemistry. Observed spermatogenic arrest was explained by the presence of considerable levels of DSB, AP sites and 8OHdG and activation of caspase 9, caspase 3 and PARP, which were measured by colorimetric assays and TUNEL. The ATM/Chk2/H2AX and ATR/Chk1 pathways were also activated as judged by their increased phosphorylation using Western blot. These observations were all prevented by AG490 inhibition of JAK2 activity. Our findings demonstrate that JAK2 regulates tIRI-induced GCA, oxidative DNA damage and activation of the ATM/Chk2/H2AX and ATR/Chk1 DDR pathways, but the cell made the apoptosis decision despite DDR efforts.