Overexpression of human catalase inhibits proliferation and promotes apoptosis in vascular smooth muscle cells

The Changes of Mitochondria during Aging and Regeneration

Aging and regeneration are opposite cellular processes. Aging refers to progressive dysfunction in most cells and tissues, and regeneration refers to the replacement of damaged or dysfunctional cells or tissues with existing adult or somatic stem cells. Various studies have shown that aging is accompanied by decreased regenerative abilities, indicating a link between them. The performance of any cellular process needs to be supported by the energy that is majorly produced by mitochondria. Thus, mitochondria may be a link between aging and regeneration. It should be interesting to discuss how mitochondria behave during aging and regeneration. The changes of mitochondria in aging and regeneration discussed in this review can provide a timely and necessary study of the causal roles of mitochondrial homeostasis in longevity and health.

o8G Site-Specifically Modified tRF-1-AspGTC: A Novel Therapeutic Target and Biomarker for Pulmonary Hypertension

BACKGROUND

Hypoxia and oxidative stress contribute to the development of pulmonary hypertension (PH). tRNA-derived fragments play important roles in RNA interference and cell proliferation, but their epitranscriptional roles in PH development have not been investigated. We aimed to gain insight into the mechanistic contribution of oxidative stress-induced 8-oxoguanine in pulmonary vascular remodeling.

METHODS

Through small RNA modification array analysis and quantitative polymerase chain reaction, a significant upregulation of the 8-oxoguanine -modified tRF-1-AspGTC was found in the lung tissues and the serum of patients with PH.

RESULTS

This modification occurs at the position 5 of the tRF-1-AspGTC (5o8G tRF). Inhibition of the 5o8G tRF reversed hypoxia-induced proliferation and apoptosis resistance in pulmonary artery smooth muscle cells. Further investigation unveiled that the 5o8G tRF retargeted mRNA of WNT5A (Wingless-type MMTV integration site family, member 5A) and CASP3 (Caspase3) and inhibited their expression. Ultimately, BMPR2 (Bone morphogenetic protein receptor 2) -reactive oxygen species/5o8G tRF/WNT5A signaling pathway exacerbated the progression of PH.

CONCLUSIONS

Our study highlights the role of site-specific 8-oxoguanine-modified tRF in promoting the development of PH. Our findings present a promising therapeutic avenue for managing PH and propose 5o8G tRF as a potential innovative marker for diagnosing this disease.

Exploring Therapeutic Potential of Catalase: Strategies in Disease Prevention and Management

The antioxidant defense mechanisms play a critical role in mitigating the deleterious effects of reactive oxygen species (ROS). Catalase stands out as a paramount enzymatic antioxidant. It efficiently catalyzes the decomposition of hydrogen peroxide (H2O2) into water and oxygen, a potentially harmful byproduct of cellular metabolism. This reaction detoxifies H2O2 and prevents oxidative damage. Catalase has been extensively studied as a therapeutic antioxidant. Its applications range from direct supplementation in conditions characterized by oxidative stress to gene therapy approaches to enhance endogenous catalase activity. The enzyme's stability, bioavailability, and the specificity of its delivery to target tissues are significant hurdles. Furthermore, studies employing conventional catalase formulations often face issues related to enzyme purity, activity, and longevity in the biological milieu. Addressing these challenges necessitates rigorous scientific inquiry and well-designed clinical trials. Such trials must be underpinned by sound experimental designs, incorporating advanced catalase formulations or novel delivery systems that can overcome existing limitations. Enhancing catalase's stability, specificity, and longevity in vivo could unlock its full therapeutic potential. It is necessary to understand the role of catalase in disease-specific contexts, paving the way for precision antioxidant therapy that could significantly impact the treatment of diseases associated with oxidative stress.

Peroxisomal hydrogen peroxide signaling: A new chapter in intracellular communication research

Hydrogen peroxide (H2O2), a natural metabolite commonly found in aerobic organisms, plays a crucial role in numerous cellular signaling processes. One of the key organelles involved in the cell's metabolism of H2O2 is the peroxisome. In this review, we first provide a concise overview of the current understanding of H2O2 as a molecular messenger in thiol redox signaling, along with the role of peroxisomes as guardians and modulators of cellular H2O2 balance. Next, we direct our focus toward the recently identified primary protein targets of H2O2 originating from peroxisomes, emphasizing their importance in unraveling the complex interplay between peroxisomal H2O2 and cell signaling. We specifically focus on three areas: signaling through peroxiredoxin redox relay complexes, calcium signaling, and phospho-signaling. Finally, we highlight key research directions that warrant further investigation to enhance our comprehension of the molecular and biochemical mechanisms linking alterations in peroxisomal H2O2 metabolism with disease.

Redox-active endosomes mediate α5β1 integrin signaling and promote chondrocyte matrix metalloproteinase production in osteoarthritis

Mechanical cues sensed by integrins induce cells to produce proteases to remodel the extracellular matrix. Excessive protease production occurs in many degenerative diseases, including osteoarthritis, in which articular cartilage degradation is associated with the genesis of matrix protein fragments that can activate integrins. We investigated the mechanisms by which integrin signals may promote protease production in response to matrix changes in osteoarthritis. Using a fragment of the matrix protein fibronectin (FN) to activate the α5β1 integrin in primary human chondrocytes, we found that endocytosis of the integrin and FN fragment complex drove the production of the matrix metalloproteinase MMP-13. Activation of α5β1 by the FN fragment, but not by intact FN, was accompanied by reactive oxygen species (ROS) production initially at the cell surface, then in early endosomes. These ROS-producing endosomes (called redoxosomes) contained the integrin-FN fragment complex, the ROS-producing enzyme NADPH oxidase 2 (NOX2), and SRC, a redox-regulated kinase that promotes MMP-13 production. In contrast, intact FN was endocytosed and trafficked to recycling endosomes without inducing ROS production. Articular cartilage from patients with osteoarthritis showed increased amounts of SRC and the NOX2 complex component p67phox. Furthermore, we observed enhanced localization of SRC and p67phox at early endosomes, suggesting that redoxosomes could transmit and sustain integrin signaling in response to matrix damage. This signaling mechanism not only amplifies the production of matrix-degrading proteases but also establishes a self-perpetuating cycle that contributes to the ongoing degradation of cartilage matrix in osteoarthritis.

Anti-oxidant potential of plants and probiotic spp. in alleviating oxidative stress induced by H2O2

Cells produce reactive oxygen species (ROS) as a metabolic by-product. ROS molecules trigger oxidative stress as a feedback response that significantly initiates biological processes such as autophagy, apoptosis, and necrosis. Furthermore, extensive research has revealed that hydrogen peroxide (H2O2) is an important ROS entity and plays a crucial role in several physiological processes, including cell differentiation, cell signalling, and apoptosis. However, excessive production of H2O2 has been shown to disrupt biomolecules and cell organelles, leading to an inflammatory response and contributing to the development of health complications such as collagen deposition, aging, liver fibrosis, sepsis, ulcerative colitis, etc. Extracts of different plant species, phytochemicals, and Lactobacillus sp (probiotic) have been reported for their anti-oxidant potential. In this view, the researchers have gained significant interest in exploring the potential plants spp., their phytochemicals, and the potential of Lactobacillus sp. strains that exhibit anti-oxidant properties and health benefits. Thus, the current review focuses on comprehending the information related to the formation of H2O2, the factors influencing it, and their pathophysiology imposed on human health. Moreover, this review also discussed the anti-oxidant potential and role of different extract of plants, Lactobacillus sp. and their fermented products in curbing H2O2‑induced oxidative stress in both in-vitro and in-vivo models via boosting the anti-oxidative activity, inhibiting of important enzyme release and downregulation of cytochrome c, cleaved caspases-3, - 8, and - 9 expression. In particular, this knowledge will assist R&D sections in biopharmaceutical and food industries in developing herbal medicine and probiotics-based or derived food products that can effectively alleviate oxidative stress issues induced by H2O2 generation.

Mitochondria spatially and temporally modulate VSMC phenotypes via interacting with cytoskeleton in cardiovascular diseases

Cardiovascular diseases caused by atherosclerosis (AS) seriously endanger human health, which is closely related to vascular smooth muscle cell (VSMC) phenotypes. VSMC phenotypic transformation is marked by the alteration of phenotypic marker expression and cellular behaviour. Intriguingly, the mitochondrial metabolism and dynamics altered during VSMC phenotypic transformation. Firstly, this review combs VSMC mitochondrial metabolism in three aspects: mitochondrial ROS generation, mutated mitochondrial DNA (mtDNA) and calcium metabolism respectively. Secondly, we summarized the role of mitochondrial dynamics in regulating VSMC phenotypes. We further emphasized the association between mitochondria and cytoskelton via presenting cytoskeletal support during mitochondrial dynamics process, and discussed its impact on their respective dynamics. Finally, considering that both mitochondria and cytoskeleton are mechano-sensitive organelles, we demonstrated their direct and indirect interaction under extracellular mechanical stimuli through several mechano-sensitive signaling pathways. We additionally discussed related researches in other cell types in order to inspire deeper thinking and reasonable speculation of potential regulatory mechanism in VSMC phenotypic transformation.

Smooth Muscle Cells from a Rat Model of Obesity and Hyperleptinemia Are Partially Resistant to Leptin-Induced Reactive Oxygen Species Generation

The aim of this study was to evaluate the effect of leptin on reactive oxygen species’ (ROS) generation of smooth muscle cells (SMCs) from a rat model of obesity and hyperleptinemia. Obesity and hyperleptinemia were induced in rats by a sucrose-based diet for 24 weeks. ROS generation was detected by using dichloro-dihydrofluorescein (DCF), a fluorescent ROS probe in primary SMCs culture. An increase in plasma leptin and oxidative stress markers was observed in sucrose-fed (SF) rats. At baseline SMCs from SF rats showed a more than twofold increase in fluorescence intensity (FI) compared to that obtained in control (C) cells. When the C cells were treated with 20 ng leptin, the FI increased by about 200%, whereas the leptin-induced FI in the SF cells increased only by 60%. In addition, sucrose feeding increased the levels of p22phox and gp91phox, subunits of Nox as an O2•− source in SMCs. Treatment of cells with leptin significantly increased p22phox and gp91phox levels in C cells and did not affect SF cells. Regarding STAT3 phosphorylation and the content of PTP1B and SOCS3 as protein markers of leptin resistance, they were found to be significantly increased in SF cells. These results suggest that SF aortic SMCs are partially resistant to leptin-induced ROS generation.

Mitotic spindle disassembly in human cells relies on CRIPT having hierarchical redox signals

Swift and complete spindle disassembly in late mitosis is essential for cell survival, yet how it happens is largely unknown in mammalian cells. Here we used real-time live cell microscopy and biochemical assays to show that the primordial dwarfism (PD)-related cysteine-rich protein CRIPT dictates the spindle disassembly in a redox-dependent manner in human cells. This previously reported cytoplasmic protein was found to have a confined nuclear localization with a nucleolar concentration during interphase but was distributed to spindles and underwent redox modifications to form disulfide bonds in CXXC pairs during mitosis. Then, it directly interacted with, and might transfer a redox response to, tubulin subunits via a putative redox exchange among cysteine residues to induce microtubule depolymerization. Expression of CRIPT proteins with mutations of these cysteine residues blocked spindle disassembly, generating two cell types with long-lasting metaphase spindles or spindle remnants. Live-cell recordings of a disease-relevant mutant (CRIPTC3Y) revealed that microtubule depolymerization at spindle ends during anaphase and the entire spindle dissolution during telophase might share a common CRIPT-bearing redox-controlled mechanism.

Impact of Oxidative Stress on Embryogenesis and Fetal Development

Multiple cellular processes are regulated by oxygen radicals or reactive oxygen species (ROS) where they play crucial roles as primary or secondary messengers, particularly during cell proliferation, differentiation, and apoptosis. Embryogenesis and organogenesis encompass all these processes; therefore, their role during these crucial life events cannot be ignored, more so when there is an imbalance in redox homeostasis. Perturbed redox homeostasis is responsible for damaging the biomolecules such as lipids, proteins, and nucleic acids resulting in leaky membrane, altered protein, enzyme function, and DNA damage which have adverse impact on the embryo and fetal development. In this article, we attempt to summarize the available data in literature for an in-depth understanding of redox regulation during development that may help in optimizing the pregnancy outcome both under natural and assisted conditions.

The Involvement of the Oxidative Stress Status in Cancer Pathology: A Double View on the Role of the Antioxidants

Oxygen-free radicals, reactive oxygen species (ROS) or reactive nitrogen species (RNS), are known by their "double-sided" nature in biological systems. The beneficial effects of ROS involve physiological roles as weapons in the arsenal of the immune system (destroying bacteria within phagocytic cells) and role in programmed cell death (apoptosis). On the other hand, the redox imbalance in favor of the prooxidants results in an overproduction of the ROS/RNS leading to oxidative stress. This imbalance can, therefore, be related to oncogenic stimulation. High levels of ROS disrupt cellular processes by nonspecifically attacking proteins, lipids, and DNA. It appears that DNA damage is the key player in cancer initiation and the formation of 8-OH-G, a potential biomarker for carcinogenesis. The harmful effect of ROS is neutralized by an antioxidant protection treatment as they convert ROS into less reactive species. However, contradictory epidemiological results show that supplementation above physiological doses recommended for antioxidants and taken over a long period can lead to harmful effects and even increase the risk of cancer. Thus, we are describing here some of the latest updates on the involvement of oxidative stress in cancer pathology and a double view on the role of the antioxidants in this context and how this could be relevant in the management and pathology of cancer.

Reactive oxygen species in exercise and insulin resistance: Working towards personalized antioxidant treatment

Reactive oxygen species (ROS) are well known for their role in insulin resistance and the development of cardiometabolic disease including type 2 diabetes mellitus (T2D). Conversely, evidence supports the notion that ROS are a necessary component for glucose cell transport and adaptation to physiological stress including exercise and muscle contraction. Although genetic rodent models and cell culture studies indicate antioxidant treatment to be an effective strategy for targeting ROS to promote health, human findings are largely inconsistent. In this review we discuss human research that has investigated antioxidant treatment and glycemic control in the context of health (healthy individuals and during exercise) and disease (insulin resistance and T2D). We have identified key factors that are likely to influence the effectiveness of antioxidant treatment: 1) the context of treatment including whether oxidative distress or eustress is present (e.g., hyperglycemia/lipidaemia or during exercise and muscle contraction); 2) whether specific endogenous antioxidant deficiencies are identified (redox screening); 3) whether antioxidant treatment is specifically designed to target and restore identified deficiencies (antioxidant specificity); 4) and the bioavailability and bioactivity of the antioxidant which are influenced by treatment dose, duration, and method of administration. The majority of human research has failed to account for these factors, limiting their ability to robustly test the effectiveness of antioxidants for health promotion and disease prevention. We propose that a modern "redox screening" and "personalized antioxidant treatment" approach is required to robustly explore redox regulation of human physiology and to elicit more effective antioxidant treatment in humans.

Tumor Tissue Oxidative Stress Changes and Na, K-ATPase Evaluation in Head and Neck Squamous Cell Carcinoma

Changes in metabolism are mechanisms that are largely implicated in the development, progression, and metastasis of head and neck squamous cell carcinoma (HNSCC) and also in resistance to different anticancer therapies. Identification of biomarkers for differentiation between cancerous and normal epithelium, treatment design and prognosis remain a vital issue in the field of head and neck cancer. The present study analyzed the main biochemical changes that occur in HNSCC tumors by through mechanisms involving oxidative stress. The release of substances reactive to thiobarbituric acid was significantly lower in HNSCC tumor tissue as compared to healthy tissue. The assays related to the lipid profile assays showed changes in membrane biophysics of tumor cells due to an increase in total phospholipids and total cholesterol, as well as an increased activity and expression of the α1 subunit of Na, K-ATPase, which is fundamental in the process of carcinogenesis. The modulation of the antioxidant system was also affected, with a decrease in the catalytic activity of the enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), as well as a reduction of glutathione (GSH) content and an increase in H₂O₂ content. A reduction in catalase (CAT) activity was observed. The data presented here are in accordance with important findings described by us in a previous study, involving the same individuals, but with a focus on the damage generated in red blood cells, resulting from tumor installation. Therefore, it was possible to conclude that the biochemical alterations found in HNSCC cells are fundamental for transformation and maintenance of the tumor cell and once it is installed, it is also capable of generating injuries in the patients' red blood cells. Our data demonstrate that this could be a promising biomarker for HNSCC.

Micro RNAs in Regulation of Cellular Redox Homeostasis

In living cells Reactive Oxygen Species (ROS) participate in intra- and inter-cellular signaling and all cells contain specific systems that guard redox homeostasis. These systems contain both enzymes which may produce ROS such as NADPH-dependent and other oxidases or nitric oxide synthases, and ROS-neutralizing enzymes such as catalase, peroxiredoxins, thioredoxins, thioredoxin reductases, glutathione reductases, and many others. Most of the genes coding for these enzymes contain sequences targeted by micro RNAs (miRNAs), which are components of RNA-induced silencing complexes and play important roles in inhibiting translation of their targeted messenger RNAs (mRNAs). In this review we describe miRNAs that directly target and can influence enzymes responsible for scavenging of ROS and their possible role in cellular redox homeostasis. Regulation of antioxidant enzymes aims to adjust cells to survive in unstable oxidative environments; however, sometimes seemingly paradoxical phenomena appear where oxidative stress induces an increase in the levels of miRNAs which target genes which are supposed to neutralize ROS and therefore would be expected to decrease antioxidant levels. Here we show examples of such cellular behaviors and discuss the possible roles of miRNAs in redox regulatory circuits and further cell responses to stress.

The FOXO signaling axis displays conjoined functions in redox homeostasis and stemness

Previous views of reactive oxygen species (ROS) depicted them as harmful byproducts of metabolism as uncontrolled levels of ROS can lead to DNA damage and cell death. However, recent studies have shed light into the key role of ROS in the self-renewal or differentiation of the stem cell. The interplay between ROS levels, metabolism, and the downstream redox signaling pathways influence stem cell fate. In this review we will define ROS, explain how they are generated, and how ROS signaling can influence transcription factors, first and foremost forkhead box-O transcription factors, that shape not only the cellular redox state, but also stem cell fate. Now that studies have illustrated the importance of redox homeostasis and the role of redox signaling, understanding the mechanisms behind this interplay will further shed light into stem cell biology.

Heparin prevents in vitro glycocalyx shedding induced by plasma from COVID-19 patients

The severe forms and worsened outcomes of COVID-19 (coronavirus disease 19) are closely associated with hypertension and cardiovascular disease. Endothelial cells express Angiotensin-Converting Enzyme 2 (ACE2), which is the entrance door for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The hallmarks of severe illness caused by SARS-CoV-2 infection are increased levels of IL-6, C-reactive protein, D-dimer, ferritin, neutrophilia and lymphopenia, pulmonary intravascular coagulopathy and microthrombi of alveolar capillaries. The endothelial glycocalyx, a proteoglycan- and glycoprotein-rich layer covering the luminal side of endothelial cells, contributes to vascular homeostasis. It regulates vascular tonus and permeability, prevents thrombosis, and modulates leukocyte adhesion and inflammatory response. We hypothesized that cytokine production and reactive oxygen species (ROS) generation associated with COVID-19 leads to glycocalyx degradation. A cohort of 20 hospitalized patients with a confirmed COVID-19 diagnosis and healthy subjects were enrolled in this study. Mechanisms associated with glycocalyx degradation in COVID-19 were investigated. Increased plasma concentrations of IL-6 and IL1-β, as well as increased lipid peroxidation and glycocalyx components were detected in plasma from COVID-19 patients compared to plasma from healthy subjects. Plasma from COVID-19 patients induced glycocalyx shedding in cultured human umbilical vein endothelial cells (HUVECs) and disrupted redox balance. Treatment of HUVECs with low molecular weight heparin inhibited the glycocalyx perturbation. In conclusion, plasma from COVID-19 patients promotes glycocalyx shedding and redox imbalance in endothelial cells, and heparin treatment potentially inhibits glycocalyx disruption.

Transduction Efficiency of Adenovirus Vectors in Endothelial Cells and Vascular Smooth Muscle Cells

Adenoviral vectors are useful tools in manipulating a gene of interest in vitro and in vivo, including in the vascular system. The transduction efficiencies of adenoviral vectors in vascular cells such as endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are known to be lower than those in epithelial cell types. The effective entry for adenoviral vectors is primarily mediated through the coxsackievirus and adenovirus receptor (CAR), which has been shown to be expressed in both cell types. Cationic liposomes have been used to enhance adenovirus transduction efficiency in nonepithelial cells. Accordingly, the aim of this study is to obtain new information regarding differences in transduction efficiencies, cationic liposome sensitivity, and CAR expression between ECs and VSMCs. Using cultured rat aortic ECs and VSMCs, here, we have compared transduction efficiency of adenoviruses with or without inclusion of liposomes and CAR expression. A significant increase in basal transduction efficiency was observed in ECs compared with VSMCs. Cationic liposome polybrene enhanced transduction efficiency in VSMCs, whereas decreased efficiency was observed in ECs. Western blotting demonstrated expression of the CAR in ECs but not in VSMCs. Proteomic analysis and mouse aorta immunostaining further suggests significant expression of the CAR in ECs but not in VSMCs. In conclusion, adenoviruses can effectively transduce the gene of interest in aortic ECs likely because of abundant expression of the CAR, whereas cationic liposomes such as polybrene enhance the transduction efficiency in VSMCs lacking CAR expression.

The homeostatic role of hydrogen peroxide, superoxide anion and nitric oxide in the vasculature

Reactive oxygen and nitrogen species are produced in a wide range of physiological reactions that, at low concentrations, play essential roles in living organisms. There is a delicate equilibrium between formation and degradation of these mediators in a healthy vascular system, which contributes to maintaining these species under non-pathological levels to preserve normal vascular functions. Antioxidants scavenge reactive oxygen and nitrogen species to prevent or reduce damage caused by excessive oxidation. However, an excessive reductive environment induced by exogenous antioxidants may disrupt redox balance and lead to vascular pathology. This review summarizes the main aspects of free radical biochemistry (formation, sources and elimination) and the crucial actions of some of the most biologically relevant and well-characterized reactive oxygen and nitrogen species (hydrogen peroxide, superoxide anion and nitric oxide) in the physiological regulation of vascular function, structure and angiogenesis. Furthermore, current preclinical and clinical evidence is discussed on how excessive removal of these crucial responses by exogenous antioxidants (vitamins and related compounds, polyphenols) may perturb vascular homeostasis. The aim of this review is to provide information of the crucial physiological roles of oxidation in the endothelium, vascular smooth muscle cells and perivascular adipose tissue for developing safer and more effective vascular interventions with antioxidants.

Reactive Oxygen Species: Modulators of Phenotypic Switch of Vascular Smooth Muscle Cells

Reactive oxygen species (ROS) are natural byproducts of oxygen metabolism in the cell. At physiological levels, they play a vital role in cell signaling. However, high ROS levels cause oxidative stress, which is implicated in cardiovascular diseases (CVD) such as atherosclerosis, hypertension, and restenosis after angioplasty. Despite the great amount of research conducted to identify the role of ROS in CVD, the image is still far from being complete. A common event in CVD pathophysiology is the switch of vascular smooth muscle cells (VSMCs) from a contractile to a synthetic phenotype. Interestingly, oxidative stress is a major contributor to this phenotypic switch. In this review, we focus on the effect of ROS on the hallmarks of VSMC phenotypic switch, particularly proliferation and migration. In addition, we speculate on the underlying molecular mechanisms of these cellular events. Along these lines, the impact of ROS on the expression of contractile markers of VSMCs is discussed in depth. We conclude by commenting on the efficiency of antioxidants as CVD therapies.

Toxic effects of arsenic trioxide on spermatogonia are associated with oxidative stress, mitochondrial dysfunction, autophagy and metabolomic alterations

Arsenic is a toxic metalloid that can cause male reproductive malfunctions and is widely distributed in the environment. The aim of this study was to investigate the cytotoxicity of arsenic trioxide (ATO) induced GC-1 spermatogonial (spg) cells. Our results found that ATO increased the levels of catalase (CAT) and malonaldehyde (MDA) and reactive oxygen species (ROS), while decreasing glutathione (GSH) and the total antioxidant capacity (T-AOC). Therefore, ATO triggered oxidative stress in GC-1 spg cells. In addition, ATO also caused severe mitochondrial dysfunction that included an increase in residual oxygen consumption (ROX), and decreased the routine respiration, maximal and ATP-linked respiration (ATP-L-R), as well as spare respiratory capacity (SRC), and respiratory control rate (RCR); ATO also damaged the mitochondrial structure, including mitochondrial cristae disordered and dissolved, mitochondrial vacuolar degeneration. Moreover, degradation of p62, LC3 conversion, increasing the number of acidic vesicle organelles (AVOs) and autophagosomes and autolysosomes are demonstrated that the cytotoxicity of ATO may be associated with autophagy. Meanwhile, the metabolomics analysis results showed that 20 metabolites (10 increased and 10 decreased) were significantly altered with the ATO exposure, suggesting that maybe there are the perturbations in amino acid metabolism, lipid metabolism, glycan biosynthesis and metabolism, metabolism of cofactors and vitamins. We concluded that ATO was toxic to GC-1 spg cells via inducing oxidative stress, mitochondrial dysfunction and autophagy as well as the disruption of normal metabolism. This study will aid our understanding of the mechanisms behind ATO-induced spermatogenic toxicity.

The effects of oxidative stress on the development of atherosclerosis

Atherosclerosis is a cardiovascular disease (CVD) known widely world wide. Several hypothesizes are suggested to be involved in the narrowing of arteries during process of atherogenesis. The oxidative modification hypothesis is related to oxidative and anti-oxidative imbalance and is the most investigated. The aim of this study was to review the role of oxidative stress in atherosclerosis. Furthermore, it describes the roles of oxidative/anti-oxidative enzymes and compounds in the macromolecular and lipoprotein modifications and in triggering inflammatory events. The reactive oxygen (ROS) and reactive nitrogen species (RNS) are the most important endogenous sources produced by non-enzymatic and enzymatic [myeloperoxidase (MPO), nicotinamide adenine dinucleotide phosphate (NADH) oxidase and lipoxygenase (LO)] reactions that may be balanced with anti-oxidative compounds [glutathione (GSH), polyphenols and vitamins] and enzymes [glutathione peroxidase (Gpx), peroxiredoxins (Prdx), superoxide dismutase (SOD) and paraoxonase (PON)]. However, the oxidative and anti-oxidative imbalance causes the involvement of cellular proliferation and migration signaling pathways and macrophage polarization leads to the formation of atherogenic plaques. On the other hand, the immune occurrences and the changes in extra cellular matrix remodeling can develop atherosclerosis process.

Peroxisomal Hydrogen Peroxide Metabolism and Signaling in Health and Disease

Hydrogen peroxide (H₂O₂), a non-radical reactive oxygen species generated during many (patho)physiological conditions, is currently universally recognized as an important mediator of redox-regulated processes. Depending on its spatiotemporal accumulation profile, this molecule may act as a signaling messenger or cause oxidative damage. The focus of this review is to comprehensively evaluate the evidence that peroxisomes, organelles best known for their role in cellular lipid metabolism, also serve as hubs in the H₂O₂ signaling network. We first briefly introduce the basic concepts of how H₂O₂ can drive cellular signaling events. Next, we outline the peroxisomal enzyme systems involved in H₂O₂ metabolism in mammals and reflect on how this oxidant can permeate across the organellar membrane. In addition, we provide an up-to-date overview of molecular targets and biological processes that can be affected by changes in peroxisomal H₂O₂ metabolism. Where possible, emphasis is placed on the molecular mechanisms and factors involved. From the data presented, it is clear that there are still numerous gaps in our knowledge. Therefore, gaining more insight into how peroxisomes are integrated in the cellular H₂O₂ signaling network is of key importance to unravel the precise role of peroxisomal H₂O₂ production and scavenging in normal and pathological conditions.

Oxidative stress in metabolic syndrome & its association with DNA-strand break

Background & objectives:

Oxidative stress (OS) is associated with numerous components of metabolic syndrome (MetS). This study was aimed to investigate if hydrogen peroxide (H₂O₂) as the reactive oxygen species was capable of depicting OS in MetS, and If MetS patients showed DNA damage in the form of DNA strand breaks (DSB).

Methods:

A total of 160 participants (90 males, 70 females) ≥20 yr of age were categorized into four groups based on the number of MetS risk parameters (n=40 in each group). Sugar and lipid profile, H₂O₂ concentration in blood and DNA-strand breaks were measured.

Results:

DSB was significantly more in those with MetS (n=40) than those without (n=120) whereas H₂O₂ levels were the same in both the study groups. The number of DSB differed significantly between the control and 3 risk factor groups. DSB was also higher in groups with 2 and 1 risk factors compared to 0 risk but the difference was not significant. H₂O₂ level was higher in groups with 3, 2 and 1 risk factors compared to 0 risk group but the difference was not significant. The H₂O₂ level correlated positively with triglyceride values but not with other MetS risk parameters. There was no significant correlation between DSB and MetS risk parameters.

Interpretation & conclusions:

Our findings showed a cumulative and synergistic effect of the risk factors of MetS on DSB. Individuals with three risk parameters had a greater effect on DNA damage than in those with two or one risk parameter. Although plasma H₂O₂ level increased with an increase in the fat depots, use of H₂O₂ to depict OS in MetS should be coupled with an adjunct and estimation of DSB in peripheral blood lymphocytes may be used as indicator of OS in MetS patients.

Redox Signaling from and to Peroxisomes: Progress, Challenges, and Prospects

SIGNIFICANCE

Peroxisomes are organelles that are best known for their role in cellular lipid and hydrogen peroxide (H₂O₂) metabolism. Emerging evidence suggests that these organelles serve as guardians and modulators of cellular redox balance, and that alterations in their redox metabolism may contribute to aging and the development of chronic diseases such as neurodegeneration, diabetes, and cancer. Recent Advances: H₂O₂ is an important signaling messenger that controls many cellular processes by modulating protein activity through cysteine oxidation. Somewhat surprisingly, the potential involvement of peroxisomes in H₂O₂-mediated signaling processes has been overlooked for a long time. However, recent advances in the development of live-cell approaches to monitor and modulate spatiotemporal fluxes in redox species at the subcellular level have opened up new avenues for research in redox biology and boosted interest in the concept of peroxisomes as redox signaling platforms.

CRITICAL ISSUES

This review first introduces the reader to what is known about the role of peroxisomes in cellular H₂O₂ production and clearance, with a focus on mammalian cells. Next, it briefly describes the benefits and drawbacks of current strategies used to investigate the complex interplay between peroxisome metabolism and cellular redox state. Furthermore, it integrates and critically evaluates literature dealing with the interrelationship between peroxisomal redox metabolism, cell signaling, and human disease.

FUTURE DIRECTIONS

As the precise molecular mechanisms underlying many of these associations are still poorly understood, a key focus for future research should be the identification of primary targets for peroxisome-derived H₂O₂.

Trimetazidine Protects Against Atherosclerosis by Changing Energy Charge and Oxidative Stress

BACKGROUND This study investigated the effect and the possible mechanism of trimetazidine in atherosclerosis. MATERIAL AND METHODS We established an atherosclerotic rat model by high-fat diet and vitamin D injection. Rats were separated into 3 different groups: control, atherosclerosis, and trimetazidine (n=10). The aortic artery was isolated and its morphological features were examined by hematoxylin and eosin (HE) staining. Serum low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC), and triglycerides (TG) were analyzed using an automatic biochemical analyzer. Human aortic smooth muscle cells (HASMCs) were cultured and divided into 5 groups: no treatment, H₂O₂ treatment only, trimetazidine preincubation before H₂O₂ treatment, oxidized low-density lipoprotein (oxLDL) treatment only, and trimetazidine preincubation before oxLDL treatment. HASMCs proliferation was tested using the Cell Counting Kit-8. Reactive oxygen species (ROS) and malondialdehyde (MDA) levels, superoxide dismutase (SOD) activity of the aortic artery, and HASMCs were measured using commercially available kits. RESULTS HE staining assay showed that trimetazidine suppressed the progression of atherosclerosis and reduced foam cell formation in the aortic artery without affecting serum lipid levels. HASMCs proliferation assay revealed that trimetazidine alleviated the inhibitory effect of H₂O₂ on HASMCs proliferation and inhibited oxLDL-induced proliferation of HASMCs. Moreover, trimetazidine ameliorated ROS up-regulation elicited by H₂O₂ or oxLDL in HASMCs. Additionally, trimetazidine restored SOD activity and reduced MDA content of HASMCs. CONCLUSIONS Trimetazidine suppressed the progression of atherosclerosis by enhancing energy value, decreasing ROS level of aortic artery, modulating HASMCs proliferation, and reducing oxidative stress in HASMCs.

Oncogenic STAT5 signaling promotes oxidative stress in chronic myeloid leukemia cells by repressing antioxidant defenses

STAT5 transcription factors are frequently activated in hematopoietic neoplasms and are targets of various tyrosine kinase oncogenes. Evidences for a crosstalk between STAT5 and reactive oxygen species (ROS) metabolism have recently emerged but mechanisms involved in STAT5-mediated regulation of ROS still remain elusive. We demonstrate that sustained activation of STAT5 induced by Bcr-Abl in chronic myeloid leukemia (CML) cells promotes ROS production by repressing expression of two antioxidant enzymes, catalase and glutaredoxin-1(Glrx1). Downregulation of catalase and Glrx1 expression was also observed in primary cells from CML patients. Catalase was shown not only to reduce ROS levels but also, to induce quiescence in Bcr-Abl-positive leukemia cells. Furthermore, reduction of STAT5 phosphorylation and upregulation of catalase and Glrx1 were also evidenced in leukemia cells co-cultured with bone marrow stromal cells to mimic a leukemic niche. This caused downregulation of ROS levels and enhancement of leukemic cell quiescence. These data support a role of persistent STAT5 signaling in the regulation of ROS production in myeloid leukemias and highlight the repression of antioxidant defenses as an important regulatory mechanism.

Reprogramming human A375 amelanotic melanoma cells by catalase overexpression: Upregulation of antioxidant genes correlates with regression of melanoma malignancy and with malignant progression when downregulated

Reactive oxygen species (ROS) are implicated in tumor transformation. The antioxidant system (AOS) protects cells from ROS damage. However, it is also hijacked by cancers cells to proliferate within the tumor. Thus, identifying proteins altered by redox imbalance in cancer cells is an attractive prognostic and therapeutic tool. Gene expression microarrays in A375 melanoma cells with different ROS levels after overexpressing catalase were performed. Dissimilar phenotypes by differential compensation to hydrogen peroxide scavenging were generated. The melanotic A375-A7 (A7) upregulated TYRP1, CNTN1 and UCHL1 promoting melanogenesis. The metastatic A375-G10 (G10) downregulated MTSS1 and TIAM1, proteins absent in metastasis. Moreover, differential coexpression of AOS genes (EPHX2, GSTM3, MGST1, MSRA, TXNRD3, MGST3 and GSR) was found in A7 and G10. Their increase in A7 improved its AOS ability and therefore, oxidative stress response, resembling less aggressive tumor cells. Meanwhile, their decrease in G10 revealed a disruption in the AOS and therefore, enhanced its metastatic capacity.

These gene signatures, not only bring new insights into the physiopathology of melanoma, but also could be relevant in clinical prognostic to classify between non aggressive and metastatic melanomas.

Vascular peroxidase 1 mediates hypoxia-induced pulmonary artery smooth muscle cell proliferation, apoptosis resistance and migration

Aims

Reactive oxygen species (ROS) play essential roles in the pulmonary vascular remodelling associated with hypoxia-induced pulmonary hypertension (PH). Vascular peroxidase 1 (VPO1) is a newly identified haeme-containing peroxidase that accelerates oxidative stress development in the vasculature. This study aimed to determine the potential role of VPO1 in hypoxia-induced PH-related vascular remodelling.

Methods and results

The vascular morphology and VPO1 expression were assessed in the pulmonary arteries of Sprague–Dawley (SD) rats. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4) and VPO1 expression and HOCl production were significantly increased in hypoxic rats, which also exhibited obvious vascular remodelling. Furthermore, a hypoxia-induced PH model was generated by exposing primary rat pulmonary artery smooth muscle cells (PASMCs) to hypoxic conditions (3% O2, 48 h), which significantly increased the expression of NOX4 and VPO1 and the production of HOCl. These hypoxic changes were accompanied by enhanced proliferation, apoptosis resistance, and migration. In PASMCs, hypoxia-induced changes, including effects on the expression of cell cycle regulators (cyclin B1 and cyclin D1), apoptosis-related proteins (bax, bcl-2, and cleaved caspase-3), migration promoters (matrix metalloproteinases 2 and 9), and NF-κB expression, as well as the production of HOCl, were all inhibited by silencing VPO1 with small interfering RNAs. Moreover, treatment with HOCl under hypoxic conditions upregulated NF-κB expression and enhanced proliferation, apoptosis resistance, and migration in PASMCs, whereas BAY 11-7082 (an inhibitor of NF-κB) significantly inhibited these effects.

Conclusion

Collectively, these results demonstrate that VPO1 promotes hypoxia-induced proliferation, apoptosis resistance, and migration in PASMCs via the NOX4/VPO1/HOCl/NF-κB signalling pathway.

Age-related Impairment of Vascular Structure and Functions

Among age-related diseases, cardiovascular and cerebrovascular diseases are major causes of death. Vascular dysfunction is a key characteristic of these diseases wherein age is an independent and essential risk factor. The present work will review morphological alterations of aging vessels in-depth, which includes the discussion of age-related microvessel loss and changes to vasculature involving the capillary basement membrane, intima, media, and adventitia as well as the accompanying vascular dysfunctions arising from these alterations.

S100B promotes injury-induced vascular remodeling through modulating smooth muscle phenotype

S100B is a biomarker of nervous system injury, but it is unknown if it is also involved in vascular injury. In the present study, we investigated S100B function in vascular remodeling following injury. Balloon injury in rat carotid artery progressively induced neointima formation while increasing S100B expression in both neointimal vascular smooth muscle (VSMC) and serum along with an induction of proliferating cell nuclear antigen (PCNA). Knockdown of S100B by its shRNA delivered by adenoviral transduction attenuated the PCNA expression and neointimal hyperplasia in vivo and suppressed PDGF-BB-induced VSMC proliferation and migration in vitro. Conversely, overexpression of S100B promoted VSMC proliferation and migration. Mechanistically, S100B altered VSMC phenotype by decreasing the contractile protein expression, which appeared to be mediated by NF-κB activity. S100B induced NF-κB-p65 gene transcription, protein expression and nuclear translocation. Blockade of NF-κB activity by its inhibitor reversed S100B-mediated downregulation of VSMC contractile protein and increase in VSMC proliferation and migration. It appeared that S100B regulated NF-κB expression through, at least partially, the Receptor for Advanced Glycation End products (RAGE) because RAGE inhibitor attenuated S100B-mediated NF-κB promoter activity as well as VSMC proliferation. Most importantly, S100B secreted from VSMC impaired endothelial tube formation in vitro, and knockdown of S100B promoted re-endothelialization of injury-denuded arteries in vivo. These data indicated that S100B is a novel regulator for vascular remodeling following injury and may serve as a potential biomarker for vascular damage or drug target for treating proliferative vascular diseases.

Nrf2 modulates cell proliferation and antioxidants defenses during liver regeneration induced by partial hepatectomy

The objective was to determine the regulatory dynamic of Nrf2 during liver regeneration and the administration of EtOH and/or the G. schiedeanum extract. Male Wistar rats weighing 200-230 g were subjected to a 70% partial hepatectomy; they were then divided into three groups (groups 1-3). During the experiment, animals in Group 1 drank only water. The other two groups (2-3) received an intragastric dose of ethanol (1.5 g/kg BW, solution at 40% in isotonic saline solution). Additionally, rats in group 3 received a geranium extract daily at a dose of 300 mg/kg BW i.g. EtOh and/or Geranium schiedeanum was administered to rats with regenerating livers for 7 days. At the end of treatment, the activity was determined of the antioxidant enzymes, DNA concentration, TBARS, and TAC, in addition to the expression of Nrf-2, Cyclin D1, and Nqo1. EtOH increased ROS and Nrf-2, which activated the antioxidant defenses and delayed liver proliferation. On the other hand, Geranium schiedeanum exerted an antioxidant effect, diminishing ROS, but Nrf-2 expression increased, favoring liver proliferation through the increase of DNA concentration and the overexpression of Cyclin D1, however it did not activate the antioxidant defenses. In sum, it can be concluded that Nrf-2 possesses a regulatory dynamic that is evident in the presence of a toxic agent (EtOH) and/or a phytochemical agent with antioxidant capacity (Geranium schiedeanum) during liver regeneration.

Effect of seven Indian plant extracts on Fenton reaction-mediated damage to DNA constituents

The influences of substoichiometric amounts of seven plant extracts in the Fenton reaction-mediated damage to deoxynucleosides, deoxynucleoside monophosphates, deoxynucleoside triphosphates, and supercoiled plasmid DNA were studied to rationalize anticancer properties reported in some of these extracts. Extracts from Acacia catechu, Emblica officinalis, Spondias dulcis, Terminalia belerica, Terminalia chebula, as well as gallic acid, epicatechin, chebulagic acid and chebulinic acid enhance the extent of damage in Fenton reactions with all monomeric substrates but protect supercoiled plasmid DNA, compared to standard Fenton reactions. The damage to pyrimidine nucleosides/nucleotides is enhanced by these extracts and compounds to a greater extent than for purine ones in a concentration dependent manner. Dolichos biflorus and Hemidesmus indicus extracts generally do not show this enhancement for the monomeric substrates though they protect plasmid DNA. Compared to standard Fenton reactions for deoxynucleosides with ethanol, the presence of these five plant extracts render ethanol scavenging less effective as the radical is generated in the vicinity of the target. Since substoichiometric amounts of these extracts and the four compounds produce this effect, a catalytic mechanism involving the presence of a ternary complex of the nucleoside/nucleotide substrate, a plant compound and the hydroxyl radical is proposed. Such a mechanism cannot operate for plasmid DNA as the planar rings in the extract compounds cannot stack with the duplex DNA bases. These plant extracts, by enhancing Fenton reaction-mediated damage to deoxynucleoside triphosphates, slow down DNA replication in rapidly dividing cancer cells, thus contributing to their anticancer properties.

Redox signaling in cardiovascular pathophysiology: A focus on hydrogen peroxide and vascular smooth muscle cells

Oxidative stress represents excessive intracellular levels of reactive oxygen species (ROS), which plays a major role in the pathogenesis of cardiovascular disease. Besides having a critical impact on the development and progression of vascular pathologies including atherosclerosis and diabetic vasculopathy, oxidative stress also regulates physiological signaling processes. As a cell permeable ROS generated by cellular metabolism involved in intracellular signaling, hydrogen peroxide (H₂O₂) exerts tremendous impact on cardiovascular pathophysiology. Under pathological conditions, increased oxidase activities and/or impaired antioxidant systems results in uncontrolled production of ROS. In a pro-oxidant environment, vascular smooth muscle cells (VSMC) undergo phenotypic changes which can lead to the development of vascular dysfunction such as vascular inflammation and calcification. Investigations are ongoing to elucidate the mechanisms for cardiovascular disorders induced by oxidative stress. This review mainly focuses on the role of H₂O₂ in regulating physiological and pathological signals in VSMC.

The Effects of Toradol on Postoperative Intimal Hyperplasia in a Rat Carotid Endarterectomy Model: Laboratory Research

Carotid endarterectomy (CEA) and more recently carotid artery stenting are the treatments of choice for atherosclerotic disease of the extracranial carotid arteries; however, early restenosis caused by neointimal hyperplasia confounds surgical therapy. Oxidative stress has been implicated in the progression of intimal hyperplasia. The authors hypothesized that ketorolac tromethamine (Toradol), a nonsteroidal antiinflammatory drug that is a potent cyclooxygenase inhibitor, would decrease oxidative stress and thereby reduce intimal hyperplasia in a rat CEA model. Twenty-nine male Sprague-Dawley rats underwent CEA and were divided into 3 treatment groups as follows: (1) control (placebo), (2) 7.5 mg/kg Toradol, and (3) 10 mg/kg Toradol. Toradol treatment began 2 days before CEA and continued for 2 weeks. Two weeks after endarterectomy, carotid arteries were fixed, harvested, and examined for platelet activity (platelet reactive units), oxidative stress (malondialdehyde and glutathione), and intimal hyperplasia (measured as percentage of luminal stenosis). Platelet activity, malondialdehyde and glutathione, and intimal hyperplasia were all significantly lowered in both 7.5- and 10-mg/kg doses of Toradol versus control. Toradol given daily beginning 2 days before CEA and ending 2 weeks after the procedure was effective at significantly reducing platelet activity, oxidative stress, and intimal hyperplasia development in the rat without any increase in bleeding. Although the mechanism of action of this reduction is not completely understood, one possible explanation may be through the inhibition of reactive oxygen species production.

Oxidative products from alcohol metabolism differentially modulate pro-inflammatory cytokine expression in Kupffer cells and hepatocytes

Pro-inflammatory cytokines play a vital role in the pathogenesis of alcoholic steatohepatitis. The present study was to determine the role of alcohol-induced oxidative stress in modulating cytokine production. A rat model of alcohol consumption was used to determine alcohol-induced hepatic cytokine expression. Chronic alcohol exposure caused lipid accumulation, oxidative stress, and inflammation in the livers of Wistar rats. The role of oxidative stress in regulating cell type-specific cytokine production was further dissected in vitro. Lipopolysaccharide (LPS) dose-dependently upregulated TNF-α, MIP-1α, MCP-1, and CINC-1 in Kupffer cells-SV40, whereas TNF-α dose-dependently induced CINC-1, IP-10, and MIP-2 expression in H4IIEC3 hepatoma cells. An additive effect on cytokine production was observed in both Kupffer cells-SV40 and hepatocytes when combined hydrogen peroxide with LPS or TNF-α, respectively, which was associated with NF-κB activation and histone H3 hyper-acetylation. Unexpectedly, an inhibitory effect of 4-hydroxynonenal on cytokine production was revealed in LPS-treated Kupffer cells-SV40. Mechanistic study showed that 4-hydroxynonenal significantly enhanced mRNA degradation of TNF-α, MCP-1, and MIP-1α, and decreased the protein levels of MCP-1 in LPS-stimulated Kupffer cells-SV40 through reducing the phosphorylation of mRNA binding proteins. This study suggests that Kupffer cells and hepatocytes express distinct pro-inflammatory cytokines/chemokines in response to alcohol intoxication, and oxidative products (4-hydroxynonenal) differentially modulate pro-inflammatory cytokine/chemokine production via NF-κB signaling, histone acetylation, and mRNA stability.

Exogenous H2O2 induces growth inhibition and cell death of human pulmonary artery smooth muscle cells via glutathione depletion

Reactive oxygen species (ROS) are associated with various pathophysiological processes of vascular smooth muscle cells (VSMCs). Pyrogallol (PG) induces the superoxide anion (O2•‑)‑mediated cell death of numerous cell types. The present study aimed to investigate the effects of exogenous hydrogen peroxide (H2O2) and PG treatment on the cell growth and death of human pulmonary artery smooth muscle cells (HPASMCs), with regards to intracellular ROS and glutathione (GSH) levels, as determined by MTT and cell number assays. H2O2 led to reduced growth of HPASMCs, with a half maximal inhibitory concentration of 250‑500 µM at 24 h, and induced apoptosis, as determined by Annexin V‑staining and benzyloxycarbonyl‑Val‑Ala‑Asp‑fluoromethylketone treatment. However, PG did not strongly induce growth inhibition and death of HPASMCs. In addition, H2O2 led to increased ROS levels, including mitochondrial O2•‑, and induced GSH depletion in HPASMCs. Treatment with N‑acetyl cysteine (NAC) attenuated apoptotic cell death and ROS levels in H2O2‑treated HPASMCs, and also prevented GSH depletion. Notably, PG treatment did not increase ROS levels, including mitochondrial O2•‑. Furthermore, NAC induced a significant increase in mitochondrial O2•‑ levels in PG‑treated HPASMCs, and cell death and GSH depletion were significantly increased. L‑buthionine sulfoximine intensified cell death and GSH depletion in PG‑treated HPASMCs. In conclusion, exogenous H2O2 induced growth inhibition and cell death of HPASMCs via GSH depletion.

Downregulation of Reactive Oxygen Species in Apoptosis

Generation of reactive oxygen species (ROS) by diverse anti-cancer drugs or phytochemicals has been closely related with the induction of apoptosis in cancers. Also, the downregulation of ROS by these chemicals has been found to block initiation of carcinogenesis. Therefore, modulation of ROS by phytochemicals emerges as a crucial mechanism to regulate apoptosis in cancer prevention or therapy. This review summarizes the current understanding of the selected chemical compounds and related cellular components that modulate ROS during apoptotic process. Metformin, quercetin, curcumin, vitamin C, and other compounds have been shown to downregulate ROS in the cellular apoptotic process, and some of them even induce apoptosis in cancer cells. The cellular components mediating the downregulation of ROS include nuclear factor erythroid 2-related factor 2 antioxidant signaling pathway, thioredoxin, catalase, glutathione, heme oxygenase-1, and uncoupling proteins. The present review provides information on the relationship between these compounds and the cellular components in modulating ROS in apoptotic cancer cells.

Paradoxical Roles of Antioxidant Enzymes: Basic Mechanisms and Health Implications

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated from aerobic metabolism, as a result of accidental electron leakage as well as regulated enzymatic processes. Because ROS/RNS can induce oxidative injury and act in redox signaling, enzymes metabolizing them will inherently promote either health or disease, depending on the physiological context. It is thus misleading to consider conventionally called antioxidant enzymes to be largely, if not exclusively, health protective. Because such a notion is nonetheless common, we herein attempt to rationalize why this simplistic view should be avoided. First we give an updated summary of physiological phenotypes triggered in mouse models of overexpression or knockout of major antioxidant enzymes. Subsequently, we focus on a series of striking cases that demonstrate "paradoxical" outcomes, i.e., increased fitness upon deletion of antioxidant enzymes or disease triggered by their overexpression. We elaborate mechanisms by which these phenotypes are mediated via chemical, biological, and metabolic interactions of the antioxidant enzymes with their substrates, downstream events, and cellular context. Furthermore, we propose that novel treatments of antioxidant enzyme-related human diseases may be enabled by deliberate targeting of dual roles of the pertaining enzymes. We also discuss the potential of "antioxidant" nutrients and phytochemicals, via regulating the expression or function of antioxidant enzymes, in preventing, treating, or aggravating chronic diseases. We conclude that "paradoxical" roles of antioxidant enzymes in physiology, health, and disease derive from sophisticated molecular mechanisms of redox biology and metabolic homeostasis. Simply viewing antioxidant enzymes as always being beneficial is not only conceptually misleading but also clinically hazardous if such notions underpin medical treatment protocols based on modulation of redox pathways.

Altered pulmonary artery endothelial-smooth muscle cell interactions in experimental congenital diaphragmatic hernia

BACKGROUND

Pulmonary hypertension (PH) secondary to vascular remodeling contributes to poor outcomes in congenital diaphragmatic hernia (CDH), however mechanisms responsible are unknown. We hypothesized that pulmonary artery endothelial cell (PAEC) dysfunction contributes to smooth muscle cell (SMC) hyperplasia in experimental CDH.

METHODS

PAEC and SMC were isolated from fetal sheep with experimental CDH and controls. SMC growth was assessed alone and with SOD plus catalase and during coculture with control or CDH PAEC with and without ET-1 siRNA transfection. ET-1 protein was measured in PAEC and SMC lysates and supernatant. ROS production was measured in normal and CDH PAECs with and without ET-1 siRNA. PAEC growth and tube formation were measured with SOD plus catalase.

RESULTS

CDH SMC growth was decreased and increased with coculture with CDH PAEC more than control PAEC. Treatment of CDH PAEC with SOD plus catalase or ET-1 siRNA prevented the increase in SMC growth seen with coculture. ET-1 protein was increased in CDH PAEC and SMC. ROS production was increased in CDH PAEC and decreased with ET-1 SiRNA. SOD plus catalase restored CDH PAEC growth and tube formation.

CONCLUSION

PAEC dysfunction in experimental CDH increases SMC proliferation via ET-1 induced ROS production by PAEC.

Interleukin-1/toll-like receptor-induced nuclear factor kappa B signaling participates in intima hyperplasia after carotid artery balloon injury in goto-kakizaki rats: a potential target therapy pathway

The value of restenosis after percutaneous coronary intervention (PCI) is recognized worldwide, especially for diabetic patients. Interleukin-1/Toll-like receptor (IL-1/TLR) signaling is involved in innate and adaptive immune responses, but whether and how the IL-1/TLR-induced nuclear factor kappa B (NFκB) pathway plays key roles in intimal formation is unclear. The underlying mechanism of intima hyperplasia was investigated with a model of carotid balloon injury in Goto-Kakizaki (GK) and Wistar rats and with lipopolysaccharide-stimulated macrophages. Elastic-van Gieson staining showed the medial area peakedon Day 3 post-injury and decreased by Day 7 post-injury in both GK and Wistar rats. The N/M at Day 7 in GK rats was significantly higher than in Wistar rats (p<0.001). The percent of 5-ethynyl-2'-deoxyuridine (EdU) staining-positive cells on Day 3 post-injury was greater than seen on Day 7 post-injury in GK and Wistar rats. The percent of EdU-positive cells on Days 3 and 7 post-injury in Wistar rats was less than that found in GK rats (p<0.01; p<0.05). NFκBp65 immunostaining had increased by Day 7 post-injury. Agilent Whole Genome Oligo Microarray verified that the IL-1/TLR-induced NFκB pathway was activated by carotid balloon injury. TLR4, IL-1 receptor associated kinase, inhibitors α of NFκB, human antigen R, c-Myc (Proto-Oncogene Proteins), EGF-like module-containing mucin-like hormone receptor-like 1 and Interleukin-6 were up-regulated or down-regulated according to immunochemistry, quantitative real-time PCR, Western blotting and Enzyme linked immunosorbent assay. Overall, we conclude that the IL-1/TLR-induced NFκB pathway participates in the intimal hyperplasia after carotid injury in GK and Wistar rats and that GK rats respond more intensely to the inflammation than Wistar rats.

Aldosterone's rapid, nongenomic effects are mediated by striatin: a modulator of aldosterone's effect on estrogen action

The cellular responses to steroids are mediated by 2 general mechanisms: genomic and rapid/nongenomic effects. Identification of the mechanisms underlying aldosterone (ALDO)'s rapid vs their genomic actions is difficult to study, and these mechanisms are not clearly understood. Recent data suggest that striatin is a mediator of nongenomic effects of estrogen. We explored the hypothesis that striatin is an intermediary of the rapid/nongenomic effects of ALDO and that striatin serves as a novel link between the actions of the mineralocorticoid and estrogen receptors. In human and mouse endothelial cells, ALDO promoted an increase in phosphorylated extracellular signal-regulated protein kinases 1/2 (pERK) that peaked at 15 minutes. In addition, we found that striatin is a critical intermediary in this process, because reducing striatin levels with small interfering RNA (siRNA) technology prevented the rise in pERK levels. In contrast, reducing striatin did not significantly affect 2 well-characterized genomic responses to ALDO. Down-regulation of striatin with siRNA produced similar effects on estrogen's actions, reducing nongenomic, but not some genomic, actions. ALDO, but not estrogen, increased striatin levels. When endothelial cells were pretreated with ALDO, the rapid/nongenomic response to estrogen on phosphorylated endothelial nitric oxide synthase (peNOS) was enhanced and accelerated significantly. Importantly, pretreatment with estrogen did not enhance ALDO's nongenomic response on pERK. In conclusion, our results indicate that striatin is a novel mediator for both ALDO's and estrogen's rapid and nongenomic mechanisms of action on pERK and phosphorylated eNOS, respectively, thereby suggesting a unique level of interactions between the mineralocorticoid receptor and the estrogen receptor in the cardiovascular system.

Binding of prorenin to (pro)renin receptor induces the proliferation of human umbilical artery smooth muscle cells via ROS generation and ERK1/2 activation

INTRODUCTION

Since the discovery of the (pro)renin receptor (PRR), it has been considered as a novel bioactive molecule of the renin-angiotensin system (RAS). The activation of PRR can elicit a series of angiotensin II (AngII)-independent effects.

MATERIALS AND METHODS

In this study, we investigated the effects of prorenin and PRR on the proliferation of human umbilical artery smooth muscle (HUASM) cells and explored the possible mechanisms underlying these effects.

RESULTS

The binding of prorenin to PRR can promote proliferation and upregulate the anti-apoptotic protein Bcl-2 and downregulate the pro-apoptotic protein Bax independently of AngII in HUASM cells. In addition, the binding of prorenin to PRR can also increase the production of reactive oxygen species (ROS) and the phosphorylation of extracellular signal-regulated kinase (ERK1/2) independently of AngII. The pretreatment of HUASM cells with an NADPH oxidase inhibitor DPI decreased the production of ROS and also decreased the phosphorylation of ERK1/2. Furthermore, pretreatment of HUASM cells with DPI and the ERK1/2 inhibitor PD98059 significantly attenuated the prorenin-induced proliferation and regulation of apoptosis factors.

CONCLUSION

Binding of prorenin to PRR can induce HUASM cell proliferation via the ROS generation and ERK1/2 activation.

Hemodynamic regulation of reactive oxygen species: implications for vascular diseases

SIGNIFICANCE

Arterial blood vessels functionally and structurally adapt to altering hemodynamic forces in order to accommodate changing needs and to provide stress homeostasis. This ability is achieved at the cellular level by converting mechanical stimulation into biochemical signals (i.e., mechanotransduction). Physiological mechanical stress helps maintain vascular structure and function, whereas pathologic or aberrant stress may impair cellular mechano-signaling, and initiate or augment cellular processes that drive disease.

RECENT ADVANCES

Reactive oxygen species (ROS) may represent an intriguing class of mechanically regulated second messengers. Chronically enhanced ROS generation may be induced by adverse mechanical stresses, and is associated with a multitude of vascular diseases. Although a causal relationship has clearly been demonstrated in large numbers of animal studies, an effective ROS-modulating therapy still remains to be established by clinical studies.

CRITICAL ISSUES AND FUTURE DIRECTIONS

This review article focuses on the role of various mechanical forces (in the form of laminar shear stress, oscillatory shear stress, or cyclic stretch) as modulators of ROS-driven signaling, and their subsequent effects on vascular biology and homeostasis, as well as on specific diseases such as arteriosclerosis, hypertension, and abdominal aortic aneurysms. Specifically, it highlights the significance of the various NADPH oxidase (NOX) isoforms as critical ROS generators in the vasculature. Directed targeting of defined components in the complex network of ROS (mechano-)signaling may represent a key for successful translation of experimental findings into clinical practice.

The chemotherapeutic potential of Terminalia ferdinandiana: Phytochemistry and bioactivity

Plants contain a myriad of natural compounds which exhibit important bioactive properties. These compounds may provide alternatives to current medications and afford a significant avenue for new drug discovery. Despite this, little information is available in the literature regarding native Australian plants and their potential for medicinal and industrial uses. Recent studies have reported Terminalia ferdinandiana to be an extremely good source of antioxidants. Indeed, T. ferdinandiana has been reported to have ascorbic acid levels per gram of fruit more than 900 times higher than blueberries. T. ferdinandiana also has high levels of a variety of other antioxidants, including phenolic compounds and anthocyanins. Antioxidants have been associated with the prevention of cancer, cardiovascular diseases, and neurological degenerative disorders. They are also linked with antidiabetic bioactivities and have been associated with the reduction of obesity. Antioxidants can directly scavenge free radicals, protecting cells against oxidative stress-related damage to proteins, lipids, and nucleic acids. Therefore, T. ferdinandiana has potential in the treatment of a variety of diseases and disorders and its potential bioactivities warrant further investigation.

Catalase prevents maternal diabetes-induced perinatal programming via the Nrf2-HO-1 defense system

We investigated whether overexpression of catalase (CAT) in renal proximal tubular cells (RPTCs) could prevent the programming of hypertension and kidney disease in the offspring of dams with maternal diabetes. Male offspring of nondiabetic and diabetic dams from two transgenic (Tg) lines (Hoxb7-green fluorescent protein [GFP]-Tg [controls] and Hoxb7/CAT-GFP-Tg, which overexpress CAT in RPTCs) were studied from the prenatal period into adulthood. Nephrogenesis, systolic blood pressure, renal hyperfiltration, kidney injury, and reactive oxygen species (ROS) generation were assessed. Gene expression of transforming growth factor-β1 (TGF-β1), nuclear factor erythroid 2p45-related factor-2 (Nrf2), and heme oxygenase-1 (HO-1) was tested in both in vitro and in vivo studies. Renal dysmorphogenesis was observed in offspring of Hoxb7-GFP-Tg dams with severe maternal diabetes; the affected male offspring displayed higher renal ROS generation and developed hypertension and renal hyperfiltration as well as renal injury with heightened TGF-β1 expression in adulthood. These changes were ameliorated in male offspring of diabetic Hoxb7/CAT-GFP-Tg dams via the Nrf2-HO-1 defense system. CAT promoted Nrf2 nuclear translocation and HO-1 gene expression, seen in both in vitro and in vivo studies. In conclusion, CAT overexpression in the RPTCs ameliorated maternal diabetes-induced perinatal programming, mediated, at least in part, by triggering the Nrf2-HO-1 defense system.

ROS homeostasis during development: an evolutionary conserved strategy

The balance between cellular proliferation and differentiation is a key aspect of development in multicellular organisms. Recent studies on Arabidopsis roots revealed distinct roles for different reactive oxygen species (ROS) in these processes. Modulation of the balance between ROS in proliferating cells and elongating cells is controlled at least in part at the transcriptional level. The effect of ROS on proliferation and differentiation is not specific for plants but appears to be conserved between prokaryotic and eukaryotic life forms. The ways in which ROS is received and how it affects cellular functioning is discussed from an evolutionary point of view. The different redox-sensing mechanisms that evolved ultimately result in the activation of gene regulatory networks that control cellular fate and decision-making. This review highlights the potential common origin of ROS sensing, indicating that organisms evolved similar strategies for utilizing ROS during development, and discusses ROS as an ancient universal developmental regulator.

Oxidative stress in apoptosis and cancer: an update

The oxygen paradox tells us that oxygen is both necessary for aerobic life and toxic to all life forms. Reactive oxygen species (ROS) touch every biological and medical discipline, especially those involving proliferative status, supporting the idea that active oxygen may be increased in tumor cells. In fact, metabolism of oxygen and the resulting toxic byproducts can cause cancer and death. Efforts to counteract the damage caused by ROS are gaining acceptance as a basis for novel therapeutic approaches, and the field of prevention of cancer is experiencing an upsurge of interest in medically useful antioxidants. Apoptosis is an important means of regulating cell numbers in the developing cell system, but it is so important that it must be controlled. Normal cell death in homeostasis of multicellular organisms is mediated through tightly regulated apoptotic pathways that involve oxidative stress regulation. Defective signaling through these pathways can contribute to both unbalance in apoptosis and development of cancer. Finally, in this review, we discuss new knowledge about recent tools that provide powerful antioxidant strategies, and designing methods to deliver to target cells, in the prevention and treatment of cancer.

Long-term adaptation of the human lung tumor cell line A549 to increasing concentrations of hydrogen peroxide

Previously, we demonstrated that A549, a human lung cancer cell line, could be adapted to the free radical nitric oxide (NO●). NO● is known to be over expressed in human tumors. The original cell line, A549 (parent), and the newly adapted A549-HNO (which has a more aggressive phenotype) serve as a useful model system to study the biology of NO●. To see if tumor cells can similarly be adapted to any free radical with the same outcome, herein we successfully adapted A549 cells to high levels of hydrogen peroxide (HHP). A549-HHP, the resulting cell line, was more resistant and grew better then the parent cell line, and showed the following characteristics: (1) resistance to hydrogen peroxide, (2) resistance to NO●, (3) growth with and without hydrogen peroxide, and (4) resistance to doxorubicin. Gene chip analysis was used to determine the global gene expression changes between A549-parent and A549-HHP and revealed significant changes in the expression of over 1,700 genes. This gene profile was markedly different from that obtained from the A549-HNO cell line. The mitochondrial DNA content of the A549-HHP line determined by quantitative PCR favored a change for a more anaerobic metabolic profile. Our findings suggest that any free radical can induce resistance to other free radicals; this is especially important given that radiation therapy and many chemotherapeutic agents exert their effect via free radicals. Utilizing this model system to better understand the role of free radicals in tumor biology will help to develop new therapeutic approaches to treat lung cancer.