Glutathione - From antioxidant to post-translational modifier

Liver epigenomic signature associated with chronic oxidative stress in a mouse model of glutathione deficiency

Oxidative stress is intimately involved in the pathogenesis of fatty liver disease (FLD). A major factor contributing to oxidative stress is the depletion of the ubiquitous antioxidant glutathione (GSH). Unexpectedly, chronic GSH deficiency renders glutamate-cysteine ligase modifier subunit (Gclm)-null mice protected from fatty liver injuries. Epigenetic regulation serves as an important cellular mechanism in modulating gene expression and disease outcome in FLD, although it is not well understood how systemic redox imbalance modifies the liver epigenome. In the current study, utilizing the Gclm-null mouse model, we aimed to elucidate redox-associated epigenomic changes and their implications in liver stress response. We performed high-throughput array-based DNA methylation profiling (MeDIP array) in 22,327 gene promoter regions (from -1300 bp to +500 bp of the Transcription Start Sites) in the liver and peripheral blood cells. Results from the MeDIP array demonstrate that, although global methylation enrichment in gene promoters did not change, low GSH resulted in prevalent demethylation at the individual promoter level. Such an effect likely attributed to a declined availability of the methyl donor S-adenosyl methionine (SAM) in Gclm-null liver. Functional enrichment analysis of liver target genes is suggestive of a potential role of epigenetic mechanisms in promoting cellular survival and lipid homeostasis in Gclm-null liver. In comparison with the liver tissue, MeDIP array in peripheral blood cells revealed a panel of 19 gene promoters that are candidate circulating biomarkers for hepatic epigenomic changes associated with chronic GSH deficiency. Collectively, our results provided new insights into the in vivo interplay between liver redox state and DNA methylation status. The current study laid the groundwork for future epigenetic/epigenomic investigations in experimental settings or human populations under conditions of liver oxidative stress induced by environmental or dietary challenges.

Hydrogen sulfide and its role in female reproduction

Hydrogen sulfide (H2S) is a gaseous signaling molecule produced in the body by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST). H2S is crucial in various physiological processes associated with female mammalian reproduction. These include estrus cycle, oocyte maturation, oocyte aging, ovulation, embryo transport and early embryo development, the development of the placenta and fetal membranes, pregnancy, and the initiation of labor. Despite the confirmed presence of H2S-producing enzymes in all female reproductive tissues, as described in this review, the exact mechanisms of H2S action in these tissues remain in most cases unclear. Therefore, this review aims to summarize the knowledge about the presence and effects of H2S in these tissues and outline possible signaling pathways that mediate these effects. Understanding these pathways may lead to the development of new therapeutic strategies in the field of women's health and perinatal medicine.

Responses and modulation of the white shrimp Litopenaeus vannamei glutathione peroxidases 2 and 4 during hypoxia, reoxygenation and GPx4 knock-down

Glutathione peroxidases (GPxs) are important antioxidant enzymes that act at distinct levels of the antioxidant defense. In vertebrates, there are several glutathione peroxidase (GPx) isoforms with different cellular and tissue distribution, but little is known about their interrelationships. The shrimp Litopenaeus vannamei is the main crustacean cultivated worldwide. It is affected by environmental stressors, including hypoxia and reoxygenation that cause reactive oxygen species accumulation. Thus, the antioxidant response modulation is key for shrimp resilience. Recently, several GPx isoforms genes were identified in the L. vannamei genome sequence, but their functions are just beginning to be studied. As in vertebrates, shrimp GPx isoforms can present differences in their antioxidant responses. Also, there could be interrelationships among the isoforms that may influence their responses. We evaluated shrimp GPx2 and GPx4 expressions during hypoxia, reoxygenation, and GPx4 knock-down using RNAi for silencing, as well as the enzymatic activity of total GPx and GPx4. Also, glutathione content in hepatopancreas was evaluated. GPx2 and GPx4 presented similar expression patterns during hypoxia and reoxygenation. Their expressions decreased during hypoxia and were reestablished in reoxygenation at 6 h in non-silenced shrimp. GPx2 expression was down-regulated by GPx4 knock-down, suggesting that GPx4 affects GPx2 expression. Total GPx activity changed in hypoxia and reoxygenation at 6 h but not at 12 h, while GPx4 activity was not affected by any stressor. The GSH/GSSG ratio in hepatopancreas indicated that at early hours, the redox status remains well-modulated but at 12 h it is impaired by hypoxia and reoxygenation.

New Weapons to Fight against Staphylococcus aureus Skin Infections

The treatment of Staphylococcus aureus skin and soft tissue infections faces several challenges, such as the increased incidence of antibiotic-resistant strains and the fact that the antibiotics available to treat methicillin-resistant S. aureus present low bioavailability, are not easily metabolized, and cause severe secondary effects. Moreover, besides the susceptibility pattern of the S. aureus isolates detected in vitro, during patient treatment, the antibiotics may never encounter the bacteria because S. aureus hides within biofilms or inside eukaryotic cells. In addition, vascular compromise as well as other comorbidities of the patient may impede proper arrival to the skin when the antibiotic is given parenterally. In this manuscript, we revise some of the more promising strategies to improve antibiotic sensitivity, bioavailability, and delivery, including the combination of antibiotics with bactericidal nanomaterials, chemical inhibitors, antisense oligonucleotides, and lytic enzymes, among others. In addition, alternative non-antibiotic-based experimental therapies, including the delivery of antimicrobial peptides, bioactive glass nanoparticles or nanocrystalline cellulose, phototherapies, and hyperthermia, are also reviewed.

Chronic Vitamin E Deficiency Dysregulates Purine, Phospholipid, and Amino Acid Metabolism in Aging Zebrafish Skeletal Muscle

Muscle wasting occurs with aging and may be a result of oxidative stress damage and potentially inadequate protection by lipophilic antioxidants, such as vitamin E. Previous studies have shown muscular abnormalities and behavioral defects in vitamin E-deficient adult zebrafish. To test the hypothesis that there is an interaction between muscle degeneration caused by aging and oxidative damage caused by vitamin E deficiency, we evaluated long-term vitamin E deficiency in the skeletal muscle of aging zebrafish using metabolomics. Zebrafish (55 days old) were fed E+ and E- diets for 12 or 18 months. Then, skeletal muscle samples were analyzed using UPLC-MS/MS. Data were analyzed to highlight metabolite and pathway changes seen with either aging or vitamin E status or both. We found that aging altered purines, various amino acids, and DHA-containing phospholipids. Vitamin E deficiency at 18 months was associated with changes in amino acid metabolism, specifically tryptophan pathways, systemic changes in the regulation of purine metabolism, and DHA-containing phospholipids. In sum, while both aging and induced vitamin E deficiency did have some overlap in altered and potentially dysregulated metabolic pathways, each factor also presented unique alterations, which require further study with more confirmatory approaches.

Brain CoA and Acetyl CoA Metabolism in Mechanisms of Neurodegeneration

The processes of biotransformation of pantothenic acid (Pan) in the biosynthesis and hydrolysis of CoA, key role of pantothenate kinase (PANK) and CoA synthetase (CoASY) in the formation of the priority mitochondrial pool of CoA, with a high metabolic turnover of the coenzyme and limited transport of Pan across the blood-brain barrier are considered. The system of acetyl-CoA, a secondary messenger, which is the main substrate of acetylation processes including formation of N-acetyl aspartate and acetylcholine, post-translational modification of histones, predetermines protection of the neurons against degenerative signals and cholinergic neurotransmission. Biochemical mechanisms of neurodegenerative syndromes in the cases of PANK and CoASY defects, and the possibility of correcting of CoA biosynthesis in the models with knockouts of these enzymes have been described. The data of a post-mortem study of the brains from the patients with Huntington's and Alzheimer's diseases are presented, proving Pan deficiency in the CNS, which is especially pronounced in the pathognomonic neurostructures. In the frontal cortex of the patients with Parkinson's disease, combined immunofluorescence of anti-CoA- and anti-tau protein was detected, reflecting CoAlation during dimerization of the tau protein and its redox sensitivity. Redox activity and antioxidant properties of the precursors of CoA biosynthesis were confirmed in vitro with synaptosomal membranes and mitochondria during modeling of aluminum neurotoxicity accompanied by the decrease in the level of CoA in CNS. The ability of CoA biosynthesis precursors to stabilize glutathione pool in neurostructures, in particular, in the hippocampus, is considered as a pathogenetic protection mechanism during exposure to neurotoxins, development of neuroinflammation and neurodegeneration, and justifies the combined use of Pan derivatives (for example, D-panthenol) and glutathione precursors (N-acetylcysteine). Taking into account the discovery of new functions of CoA (redox-dependent processes of CoAlation of proteins, possible association of oxidative stress and deficiency of Pan (CoA) in neurodegenerative pathology), it seems promising to study bioavailability and biotransformation of Pan derivatives, in particular of D-panthenol, 4'-phospho-pantetheine, its acylated derivatives, and compositions with redox pharmacological compounds, are promising for their potential use as etiopathogenetic agents.

Influenza virus replication is affected by glutaredoxin1-mediated protein deglutathionylation

Several redox modifications have been described during viral infection, including influenza virus infection, but little is known about glutathionylation and this respiratory virus. Glutathionylation is a reversible, post-translational modification, in which protein cysteine forms transient disulfides with glutathione (GSH), catalyzed by cellular oxidoreductases and in particular by glutaredoxin (Grx). We show here that (i) influenza virus infection induces protein glutathionylation, including that of viral proteins such as hemagglutinin (HA); (ii) Grx1-mediated deglutathionylation is important for the viral life cycle, as its inhibition, either with an inhibitor of its enzymatic activity or by siRNA, decreases viral replication. Overall these data contribute to the characterization of the complex picture of redox regulation of the influenza virus replication cycle and could help to identify new targets to control respiratory viral infection.

Effects of methionine intake on cognitive function in mild cognitive impairment patients and APP/PS1 Alzheimer's Disease model mice: Role of the cystathionine-β-synthase/H2S pathway

As a dietary intervention, methionine restriction (MR) has been reported to increase longevity and improve metabolism disorders. However, the effects of MR on alleviating neurodegenerative diseases such as Alzheimer's disease (AD) are largely unexplored. Here we sought to investigate the neuroprotective effects of low methionine intake in mild cognitive impairment (MCI) patients and APP/PS1 AD model mice, and to uncover the underlying mechanisms. In a cohort composed of 45 individuals diagnosed with MCI and 61 healthy controls without cognitive impairment, methionine intake was found to be positively associated with the increased risk of MCI, where no sex differences were observed. We further conducted a 16-week MR intervention (0.17% methionine, w/w) on APP/PS1 AD model mice. Although MR reduced Aβ accumulation in the brain of both male and female APP/PS1 mice, MR improved cognitive function only in male mice, as assessed by the Morris water maze test. Consistently, MR restored synapse ultrastructure and alleviated mitochondrial dysfunction by enhancing mitochondrial biogenesis in the brain of male APP/PS1 mice. Importantly, MR effectively balanced the redox status and activated cystathionine-β-synthase (CBS)/H₂S pathway in the brain of male APP/PS1 mice. Together, our study indicated that lower dietary methionine intake is associated with improved cognitive function, in which CBS/H₂S pathway plays an essential role. MR could be a promising nutritional intervention for preventing AD development.

Recent Developments in the Understanding of Immunity, Pathogenesis and Management of COVID-19

Coronaviruses represent a diverse family of enveloped positive-sense single stranded RNA viruses. COVID-19, caused by Severe Acute Respiratory Syndrome Coronavirus-2, is a highly contagious respiratory disease transmissible mainly via close contact and respiratory droplets which can result in severe, life-threatening respiratory pathologies. It is understood that glutathione, a naturally occurring antioxidant known for its role in immune response and cellular detoxification, is the target of various proinflammatory cytokines and transcription factors resulting in the infection, replication, and production of reactive oxygen species. This leads to more severe symptoms of COVID-19 and increased susceptibility to other illnesses such as tuberculosis. The emergence of vaccines against COVID-19, usage of monoclonal antibodies as treatments for infection, and implementation of pharmaceutical drugs have been effective methods for preventing and treating symptoms. However, with the mutating nature of the virus, other treatment modalities have been in research. With its role in antiviral defense and immune response, glutathione has been heavily explored in regard to COVID-19. Glutathione has demonstrated protective effects on inflammation and downregulation of reactive oxygen species, thereby resulting in less severe symptoms of COVID-19 infection and warranting the discussion of glutathione as a treatment mechanism.

Glutathione in Brain Disorders and Aging

Glutathione is a remarkably functional molecule with diverse features, which include being an antioxidant, a regulator of DNA synthesis and repair, a protector of thiol groups in proteins, a stabilizer of cell membranes, and a detoxifier of xenobiotics. Glutathione exists in two states—oxidized and reduced. Under normal physiological conditions of cellular homeostasis, glutathione remains primarily in its reduced form. However, many metabolic pathways involve oxidization of glutathione, resulting in an imbalance in cellular homeostasis. Impairment of glutathione function in the brain is linked to loss of neurons during the aging process or as the result of neurological diseases such as Huntington’s disease, Parkinson’s disease, stroke, and Alzheimer’s disease. The exact mechanisms through which glutathione regulates brain metabolism are not well understood. In this review, we will highlight the common signaling cascades that regulate glutathione in neurons and glia, its functions as a neuronal regulator in homeostasis and metabolism, and finally a mechanistic recapitulation of glutathione signaling. Together, these will put glutathione’s role in normal aging and neurological disorders development into perspective.

SIRT3 protects bovine mammary epithelial cells from heat stress damage by activating the AMPK signaling pathway

With global warming, heat stress has become an important challenge for the global dairy industry. Sirtuin 3 (SIRT3), an important mitochondrial NAD+dependent decarboxylase and a major regulator of cellular energy metabolism and antioxidant defense, is integral to maintaining normal mitochondrial function. The aim of this study was to assess the protective effect of SIRT3 on damage to bovine mammary epithelial cells (BMECs) induced by heat stress and to explore its potential mechanism. Our results indicate that SIRT3 is significantly downregulated in heat-stressed mammary tissue and high-temperature-treated BMECs. SIRT3 knockdown significantly increased the expression of HSP70, Bax, and cleaved-caspase 3 and inhibited the production of antioxidases, thus promoting ROS production and cell apoptosis in BMECs. In addition, SIRT3 knockdown can aggravate mitochondrial damage by mediating the expression of genes related to mitochondrial fission and fusion, including dynamin-related protein 1, mitochondrial fission 1 protein, and mitochondrial fusion proteins 1and 2. In addition, SIRT3 knockdown substantially decreased AMPK phosphorylation in BMECs. In contrast, SIRT3 overexpression in high-temperature treatment had the opposite effect to SIRT3 knockdown in BMECs. SIRT3 overexpression reduced mitochondrial damage and weakened the oxidative stress response of BMECs induced by heat stress and promoted the phosphorylation of AMPK. Taken together, our results indicate that SIRT3 can protect BMECs from heat stress damage through the AMPK signaling pathway. Therefore, the reduction of oxidative stress by SIRT3 may be the primary molecular mechanism underlying resistance to heat stress in summer cows.

Therapeutic Potential of Alpha-Lipoic Acid in Viral Infections, including COVID-19

Oxidative stress (OS), resulting from a disrupted balance between reactive oxygen species (ROS) and protective antioxidants, is thought to play an important pathogenetic role in several diseases, including viral infections. Alpha-lipoic acid (LA) is one of the most-studied and used natural compounds, as it is endowed with a well-defined antioxidant and immunomodulatory profile. Owing to these properties, LA has been tested in several chronic immunoinflammatory conditions, such as diabetic neuropathy and metabolic syndrome. In addition, a pharmacological antiviral profile of LA is emerging, that has attracted attention on the possible use of this compound for the cotreatment of several viral infections. Here, we will review the emerging literature on the potential use of LA in viral infections, including COVID-19.

Nonenzymatic Stereoselective S-Glycosylation of Polypeptides and Proteins

Here we report a nonenzymatic glycosylation reaction that builds axial S-glycosidic bonds under biorelevant conditions. This strategy is enabled by the design and use of allyl glycosyl sulfones as precursors to glycosyl radicals and exploits the exceptional functional group tolerance of radical processes. Our method introduces a variety of unprotected glycosyl units to the cysteine residues of peptides in a highly selective fashion. Through developing the second-generation protocol, we applied our method in the direct glycosylation of complex polypeptides and proteins. Computational studies were performed to elucidate the reaction mechanism.

Glutathione Participation in the Prevention of Cardiovascular Diseases

Cardiovascular diseases (CVD) (such as occlusion of the coronary arteries, hypertensive heart diseases and strokes) are diseases that generate thousands of patients with a high mortality rate worldwide. Many of these cardiovascular pathologies, during their development, generate a state of oxidative stress that leads to a deterioration in the patient’s conditions associated with the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Within these reactive species we find superoxide anion (O₂^•–), hydroxyl radical (^•OH), nitric oxide (NO^•), as well as other species of non-free radicals such as hydrogen peroxide (H₂O₂), hypochlorous acid (HClO) and peroxynitrite (ONOO^–). A molecule that actively participates in counteracting the oxidizing effect of reactive species is reduced glutathione (GSH), a tripeptide that is present in all tissues and that its synthesis and/or regeneration is very important to be able to respond to the increase in oxidizing agents. In this review, we will address the role of glutathione, its synthesis in both the heart and the liver, and its importance in preventing or reducing deleterious ROS effects in cardiovascular diseases.

Short Duration Alagebrium Chloride Therapy Prediabetes Does Not Inhibit Progression to Autoimmune Diabetes in an Experimental Model

Mechanisms by which advanced glycation end products (AGEs) contribute to type 1 diabetes (T1D) pathogenesis are poorly understood. Since life-long pharmacotherapy with alagebrium chloride (ALT) slows progression to experimental T1D, we hypothesized that acute ALT therapy delivered prediabetes, may be effective. However, in female, non-obese diabetic (NODShiLt) mice, ALT administered prediabetes (day 50-100) did not protect against experimental T1D. ALT did not decrease circulating AGEs or their precursors. Despite this, pancreatic β-cell function was improved, and insulitis and pancreatic CD45.1+ cell infiltration was reduced. Lymphoid tissues were unaffected. ALT pre-treatment, prior to transfer of primed GC98 CD8+ T cell receptor transgenic T cells, reduced blood glucose concentrations and delayed diabetes, suggesting islet effects rather than immune modulation by ALT. Indeed, ALT did not reduce interferon-γ production by leukocytes from ovalbumin-pre-immunised NODShiLt mice and NODscid recipients given diabetogenic ALT treated NOD splenocytes were not protected against T1D. To elucidate β-cell effects, NOD-derived MIN6N8 β-cell major histocompatibility complex (MHC) Class Ia surface antigens were examined using immunopeptidomics. Overall, no major changes in the immunopeptidome were observed during the various treatments with all peptides exhibiting allele specific consensus binding motifs. As expected, longer MHC Class Ia peptides were captured bound to H-2Db than H-2Kb under all conditions. Moreover, more 10-12 mer peptides were isolated from H-2Db after AGE modified bovine serum albumin (AGE-BSA) treatment, compared with bovine serum albumin (BSA) or AGE-BSA+ALT treatment. Proteomics of MIN6N8 cells showed enrichment of processes associated with catabolism, the immune system, cell cycling and presynaptic endocytosis with AGE-BSA compared with BSA treatments. These data show that short-term ALT intervention, given prediabetes, does not arrest experimental T1D but transiently impacts β-cell function.

Red-Fleshed Apple Anthocyanin Extracts Attenuate Male Reproductive System Dysfunction Caused by Busulfan in Mice

In this research, we analyzed the effect of an intragastrical oral administration of red-fleshed apple anthocyanin extract (RAAE) on busulfan-treated mice. First, we showed that the most abundant component in RAAE was cyanidin 3-O-galactoside. To determine the effect of the RAAE, the mice were divided into control and four other different concentrations of RAAE feeding treatment groups (BA0, no RAAE; BA.1, 0.1 mg/kg; BA1, 1 mg/kg; and BA5, 5 mg/kg) following busulfan injection. We observed that RAAE treatments displayed ameliorative effects on male reproductive system dysfunction caused by busulfan, such as recovering the irregular arrangements of seminiferous tubules, increasing the number of spermatogonia and spermatocytes, improving sperm concentration by 3-fold in BA.1, and improving sperm motility by 2-fold in BA1. The liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis showed significant up- or downregulation of certain metabolites, such as lysophosphatidylcholine (LysoPC), L-arginine, glycine, anandamide, and L-carnitine, which could contribute to the positive effects of RAAE, especially in PBA1 (plasma of BA1) and PBA5 (plasma of BA5). Taken together, the results indicate that 1 mg/kg of RAAE is a suitable concentration for rescuing spermatogenesis in mice. The research suggests that RAAE could be a potential nutraceutical for protecting spermatogenesis after busulfan therapy in cancer.

Adaptive epigenetic response of glutathione (GSH)-related genes against lead (Pb)-induced toxicity, in individuals chronically exposed to the metal

It is well known that one of the most outstanding adverse effects related to lead (Pb) exposure is oxidative stress; moreover, recent findings suggest that disturbances of the redox status of cells are associated with epigenetic responses, and metabolism of glutathione (GSH) plays an important role in this process. This study aimed to assess Pb exposure on % methylation of GSH-related genes' promoter regions (%CH₃-CpG) and their influence on biomarkers of oxidative stress, in workers exposed to the metal. One hundred nine male workers participated in the study; ICP-MS determined blood lead levels (BLL); biochemical parameters related to redox status, named GSH, glutathione peroxidase (GPX) and glutathione-S-transferase (GST) were quantified by UV/Vis spectrophotometry. Determination of %CH₃-CpG of genes GCLC, GPX1, GSR, and GSTP1 were done by pyrosequencing. Inverse associations were seen between BLL and %CH₃-CpG-GCLC, and %CH₃-CpG-GSTP1. Moreover, metal exposure did not impact GSH, GPX, and GST; however, negative associations were observed between %CH₃-CpG-GPX1 and %CH₃-CpG-GSTP1, and the activities of GPX and GST, respectively. Taken together, our results give further evidence about adaptive epigenetic response to avoid oxidative damage induced by Pb exposure, allowing a better understanding of the molecular mechanisms related to the metal toxicity.

Ameliorative impacts of Allium cepa Linnaeus aqueous extract against testicular damage induced by dexamethasone

The present study aimed to explore the impact of onion (Allium cepa Linnaeus) extract on testicular damage induced by dexamethasone. Forty male Wistar rats were divided into four groups (control, dexamethasone, onion extract and dexamethasone group treated with onion extract). Testosterone levels, antioxidant parameters and the expression of caspase-3 and IL-1β, IL-12, IL-10 genes, as well as histopathological examination and immunohistochemical studies of Bcl2 and caspase-9 expression, were examined. Dexamethasone was found to decrease GSH, total antioxidant activity and testosterone levels, meanwhile treatment with onion extract normalised these levels. MDA was increased in dexamethasone group but appeared normal in the treated group. Dexamethasone was shown to downregulate IL-10 and IL-2 gene expression. Conversely, IL-1β and caspase-3 gene expression were upregulated by dexamethasone and normalised in the treated group. Histopathological analysis found that dexamethasone caused atrophy to the seminiferous tubules and degeneration to spermatocytes, and immunohistochemical analysis showed overexpression of caspase-9 and inhibited the expression of Bcl-2 in dexamethasone group. These effects were normalised in the onion extract treated group. In conclusion, onion extract have a preventative effect against dexamethasone-induced testicular damage in rats; therefore, its use in complementary therapy is recommended.

Nitric oxide, other reactive signalling compounds, redox, and reductive stress

Nitric oxide (NO) and other reactive nitrogen species (RNS) are key signalling molecules in plants, but they do not work in isolation. NO is produced in cells, often increased in response to stress conditions, but many other reactive compounds used in signalling are generated and accumulate spatially and temporally together. This includes the reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), and hydrogen sulfide (H2S). Here, the interactions with such other reactive molecules is briefly reviewed. Furthermore, along with ROS and H2S, NO will potentially contribute to the overall intracellular redox of the cell. However, RNS will exist in redox couples and therefore the influence of the cellular redox on such couples will be explored. In discussions of the aberrations in intracellular redox it is usually oxidation, so-called oxidative stress, which is discussed. Here, we consider the notion of reductive stress and how this may influence the signalling which may be mediated by NO. By getting a more holistic view of NO biology, the influence on cell activity of NO and other RNS can be more fully understood, and may lead to the elucidation of methods for NO-based manipulation of plant physiology, leading to better stress responses and improved crops in the future.

Cystathionine γ-lyase promotes estrogen-stimulated uterine artery blood flow via glutathione homeostasis

During pregnancy, estrogen (E₂) stimulates uterine artery blood flow (UBF) by enhancing nitric oxide (NO)-dependent vasodilation. Cystathionine γ-lyase (CSE) promotes vascular NO signaling by producing hydrogen sulfide (H₂S) and by maintaining the ratio of reduced-to-oxidized intracellular glutathione (GSH/GSSG) through l-cysteine production. Because redox homeostasis can influence NO signaling, we hypothesized that CSE mediates E₂ stimulation of UBF by modulating local intracellular cysteine metabolism and GSH/GSSG levels to promote redox homeostasis. Using non-pregnant ovariectomized WT and CSE-null (CSE KO) mice, we performed micro-ultrasound of mouse uterine and renal arteries to assess changes in blood flow upon exogenous E₂ stimulation. We quantified serum and uterine artery NO metabolites (NO_x), serum amino acids, and uterine and renal artery GSH/GSSG. WT and CSE KO mice exhibited similar baseline uterine and renal blood flow. Unlike WT, CSE KO mice did not exhibit expected E₂ stimulation of UBF. Renal blood flow was E₂-insensitive for both genotypes. While serum and uterine artery NO_x were similar between genotypes at baseline, E₂ decreased NO_x in CSE KO serum. Cysteine was also lower in CSE KO serum, while citrulline and homocysteine levels were elevated. E₂ and CSE deletion additively decreased GSH/GSSG in uterine arteries. In contrast, renal artery GSH/GSSG was insensitive to E₂ or CSE deletion. Together, these findings suggest that CSE maintenance of uterine artery GSH/GSSG facilitates nitrergic signaling in uterine arteries and is required for normal E₂ stimulation of UBF. These data have implications for pregnancy pathophysiology and the selective hormone responses of specific vascular beds.

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CSE-null mice exhibit abnormal estrogen augmentation of uterine artery blood flow.

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Estrogen lowers uterine artery nitric oxide metabolites in CSE null mice.

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CSE loss and estrogen additively impair uterine artery glutathione homeostasis.

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Neither CSE loss nor estrogen influences renal artery blood flow or glutathione.

The impact of curcumin-graphene based nanoformulation on cellular interaction and redox-activated apoptosis: An in vitro colon cancer study

Natural plants derivatives have gained enormous merits in cancer therapy applications upon formulation with nanomaterials. Curcumin, as a popular research focus has acquired such improvements surpassing its disadvantageous low bioavailability. To this point, the available research data had confirmed the importance of nanomaterial type in orienting cellular response and provoking different toxicological and death mechanisms that may range from physical membrane damage to intracellular changes. This in turn underlines the poorly studied field of nanoformulation interaction with cells as the key determinant in toxicology outcomes. In this work, curcumin-AuNPs-reduced graphene oxide nanocomposite (CAG) was implemented as a model, to study the impact on cellular membrane integrity and the possible redox changes using colon cancer in vitro cell lines (HT-29 and SW-948), representing drug-responsive and resistant subtypes. Morphological and biochemical methods of transmission electron microscopy (TEM), apoptosis assay, reactive oxygen species (ROS) and antioxidants glutathione and superoxide dismutase (GSH and SOD) levels were examined with consideration to suitable protocols and vital optimizations. TEM micrographs proved endocytic uptake with succeeding cytoplasm deposition, which unlike other nanomaterials studied previously, conserved membrane integrity allowing intracellular cytotoxic mechanism. Apoptosis was confirmed with gold-standard morphological features observed in micrographs, while redox parameters revealed a time-dependent increase in ROS accompanied with regressive GSH and SOD levels. Collectively, this work demonstrates the success of graphene as a platform for curcumin intracellular delivery and cytotoxicity, and further highlights the importance of suitable in vitro methods to be used for nanomaterial validation.

The Cutaneous Physiological Redox: Essential to Maintain but Difficult to Define

Skin is a unique tissue, possessing extremely efficient protective and regulative mechanisms, similar only to the gut and lungs. These tissues serve as an interface with the environment and are exposed to stressors from both endogenous and exogenous sources. Interestingly, all these stressors lead downstream to a cellular production of reactive oxygen species (ROS) and other electrophiles, which, in turn could have deleterious outcomes for the living organism. Hence, such tissues should always maintain a “high-alert” condition in order to cope with these various insults. Nevertheless, a moderate production of ROS induced by stressors could actually be beneficial, although it is impossible to predict if and which exposure would lead to which outcome. Consequently, a parameter which would indicate the skin’s readiness to cope with continuously fluctuating conditions is required. It has been proposed that the redox status may serve as a suitable indicator. In this opinion manuscript, we argue that the redox status is a vague parameter that is difficult to characterized and quantify due to its extremely dynamic nature. The common convention that the redox status is composed solely of the balance between oxidants and reductants (ROS and antioxidants) is also thought-provoking. Since this parameter in vivo behaves in a dynamic and complex manner, it better fits the description of a process, rather than an individual parameter. We suggest that the homeostatic modulation of the physiological redox (PR) should be in focus, rather than the redox status parameter itself. It is further suggested that low molecular weight antioxidants (LMWA) are, in fact, rather insignificant concerning the PR maintenance, and that the major contributors to this delicate modulation are regulative, protein-based systems such as the protective phase II antioxidant enzymes. Moreover, we show that skin microbiome and cutaneous advanced lipid peroxidation end-products (ALEs) take part in sustaining the cutaneous PR homoeostasis via activation of the Nrf2–Keap1 protective pathway.

Nitric Oxide-Releasing Thermoresponsive Pluronic F127/Alginate Hydrogel for Enhanced Antibacterial Activity and Accelerated Healing of Infected Wounds

Nitric oxide (NO), a highly reactive and lipophilic molecule, is one of the molecules present in the wound environment and implicated as an important regulator in all phases of wound healing. Here, we developed an NO-releasing thermoresponsive hydrogel (GSNO-PL/AL) composed of S-nitrosoglutathione (GSNO), pluronic F127 (PL), and alginate (AL) for the treatment of infected wounds. The GSNO was incorporated into the thermoresponsive PL/AL hydrogel, and differential scanning calorimetry techniques were used for the hydrogel characterization. The hydrogel was assessed by in vitro NO release, antibacterial activity, cytotoxicity, and wound-healing activity. The GSNO-PL/AL hydrogel demonstrated thermal responsiveness and biocompatibility, and it showed sustained NO release for 7 days. It also exhibited potent bactericidal activity against Gram-positive methicillin-resistant Staphylococcus aureus and Gram-negative multidrug-resistant Pseudomonas aeruginosa (MRPA). Moreover, the GSNO-PL/AL treatment of MRPA-infected wounds accelerated healing with a reduced bacterial burden in the wounds. The GSNO-PL/AL hydrogel would be a promising option for the treatment of infected wounds.

Nitric Oxide-Releasing S-Nitrosoglutathione-Conjugated Poly(Lactic-Co-Glycolic Acid) Nanoparticles for the Treatment of MRSA-Infected Cutaneous Wounds

S-nitrosoglutathione (GSNO) has emerged as a potent agent for the treatment of infected cutaneous wounds. However, fabrication of GSNO-containing nanoparticles has been challenging due to its high hydrophilicity and degradability. The present study aimed to fabricate nanoparticles using newly synthesized GSNO-conjugated poly(lactic-co-glycolic acid) (PLGA) (GSNO-PLGA; GPNPs). Since hydrophilic GSNO was covalently bound to hydrophobic PLGA, loss of GSNO during the nanoparticle fabrication process was minimized, resulting in sufficient loading efficiency (2.32% of GSNO, 0.07 μmol/mg of NO). Real-time NO release analysis revealed biphasic NO release by GPNPs, including initial burst release within 3 min and continuous controlled release for up to 11.27 h, due to the differential degradation rates of the –SNO groups located at the surface and inside of GPNPs. Since GPNPs could deliver NO more efficiently than GSNO in response to increased interaction with bacteria, the former showed enhanced antibacterial effects against methicillin-resistant Staphylococcus aureus (MRSA) at the same equivalent concentrations of NO. Finally, the facilitating effects of GPNPs on infected wound healing were demonstrated in MRSA-challenged full-thickness wound mouse model. Collectively, the results suggested GPNPs as an ideal nanoparticle formulation for the treatment of MRSA-infected cutaneous wounds.

Redox-Modulating Agents in the Treatment of Viral Infections

Viruses use cell machinery to replicate their genome and produce viral proteins. For this reason, several intracellular factors, including the redox state, might directly or indirectly affect the progression and outcome of viral infection. In physiological conditions, the redox balance between oxidant and antioxidant species is maintained by enzymatic and non-enzymatic systems, and it finely regulates several cell functions. Different viruses break this equilibrium and induce an oxidative stress that in turn facilitates specific steps of the virus lifecycle and activates an inflammatory response. In this context, many studies highlighted the importance of redox-sensitive pathways as novel cell-based targets for therapies aimed at blocking both viral replication and virus-induced inflammation. In the review, we discuss the most recent findings in this field. In particular, we describe the effects of natural or synthetic redox-modulating molecules in inhibiting DNA or RNA virus replication as well as inflammatory pathways. The importance of the antioxidant transcription factor Nrf2 is also discussed. Most of the data reported here are on influenza virus infection. We believe that this approach could be usefully applied to fight other acute respiratory viral infections characterized by a strong inflammatory response, like COVID-19.

A Translational In Vivo and In Vitro Metabolomic Study Reveals Altered Metabolic Pathways in Red Blood Cells of Type 2 Diabetes

Clinical parameters used in type 2 diabetes mellitus (T2D) diagnosis and monitoring such as glycosylated haemoglobin (HbA1c) are often unable to capture important information related to diabetic control and chronic complications. In order to search for additional biomarkers, we performed a pilot study comparing T2D patients with healthy controls matched by age, gender, and weight. By using ¹H-nuclear magnetic resonance (NMR) based metabolomics profiling of red blood cells (RBCs), we found that the metabolic signature of RBCs in T2D subjects differed significantly from non-diabetic controls. Affected metabolites included glutathione, 2,3-bisphophoglycerate, inosinic acid, lactate, 6-phosphogluconate, creatine and adenosine triphosphate (ATP) and several amino acids such as leucine, glycine, alanine, lysine, aspartate, phenylalanine and tyrosine. These results were validated by an independent cohort of T2D and control patients. An analysis of the pathways in which these metabolites were involved showed that energetic and redox metabolism in RBCs were altered in T2D, as well as metabolites transported by RBCs. Taken together, our results revealed that the metabolic profile of RBCs can discriminate healthy controls from T2D patients. Further research is needed to determine whether metabolic fingerprint in RBC could be useful to complement the information obtained from HbA1c and glycemic variability as well as its potential role in the diabetes management.

Antidiabetic effect of Drymaria cordata leaf against streptozotocin-nicotinamide-induced diabetic albino rats

Drymaria cordata (Caryophyllaceae), commonly known as Abhijalo in Sikkimese-Tibetan, is a creeping herb grown in tropical and subtropical regions of the world. It is used by ethnic groups of Sikkim, North-East India, for the treatment of various diseases including diabetes. This study aimed to investigate the antidiabetic effect of methanol extract from D. cordata leaf (DCME) in streptozotocin (STZ) and nicotinamide (NA)-induced type 2 diabetes in rats. Diabetic Wistar albino rats were treated with DCME at 200 mg/kg and 400 mg/kg orally for 28 days. Metformin (150 mg/kg b.w.) was used as a reference drug. Fasting blood glucose (FBG) level; serum biochemical parameters; and liver, kidney, and antioxidant parameters were estimated, and pancreatic histopathology was performed after 28 days of treatment. Administration of DCME to STZ-NA-induced diabetic rats at 200 mg/kg and 400 mg/kg orally for 28 days exhibited statistically significant (P < 0.05) and dose-dependent reduction of FBG, glycosylated hemoglobin, serum lipid, and hepatorenal antioxidative parameters in DCME-treated groups when compared to those of diabetic controls. Histopathological studies of pancreas in DCME-treated rats showed improvement in β-cell density compared to diabetic group. The results demonstrate the significant antidiabetic potential of D. cordata leaf in albino rats plausibly by reducing oxidative stress and serum lipids levels, justifying the folkloric use of this plant in the treatment of diabetes.

Alginate oligosaccharides improve germ cell development and testicular microenvironment to rescue busulfan disrupted spermatogenesis

Rationale: Busulfan is currently an indispensable anti-cancer drug, particularly for children, but the side effects on male reproduction are so serious that critical drug management is needed to minimize any negative impact. Meanwhile, alginate oligosaccharides (AOS) are natural products with many consequent advantages, that have attracted a great deal of pharmaceutical attention. In the current investigation, we performed single-cell RNA sequencing on murine testes treated with busulfan and/or AOS to define the mitigating effects of AOS on spermatogenesis at the single cell level.

Methods: Testicular cells (in vivo) were examined by single cell RNA sequencing analysis, histopathological analysis, immunofluorescence staining, and Western blotting. Testes samples (ex vivo) underwent RNA sequencing analysis. Blood and testicular metabolomes were determined by liquid chromatography-mass spectrometry (LC/MS).

Results: We found that AOS increased murine sperm concentration and motility, and rescued busulfan disrupted spermatogenesis through improving (i) the proportion of germ cells, (ii) gene expression important for spermatogenesis, and (iii) transcriptional factors in vivo. Furthermore, AOS promoted the ex vivo expression of genes important for spermatogenesis. Finally, our results showed that AOS improved blood and testis metabolomes as well as the gut microbiota to support the recovery of spermatogenesis.

Conclusions: AOS could be used to improve fertility in patients undergoing chemotherapy and to combat other factors that induce infertility in humans.

Cytoprotective Effects of Dinitrosyl Iron Complexes on Viability of Human Fibroblasts and Cardiomyocytes

Nitric oxide (NO) is an important signaling molecule that plays a key role in maintaining vascular homeostasis. Dinitrosyl iron complexes (DNICs) generating NO are widely used to treat cardiovascular diseases. However, the involvement of DNICs in the metabolic processes of the cell, their protective properties in doxorubicin-induced toxicity remain to be clarified. Here, we found that novel class of mononuclear DNICs with functional sulfur-containing ligands enhanced the cell viability of human lung fibroblasts and rat cardiomyocytes. Moreover, DNICs demonstrated remarkable protection against doxorubicin-induced toxicity in fibroblasts and in rat cardiomyocytes (H9c2 cells). Data revealed that the DNICs compounds modulate the mitochondria function by decreasing the mitochondrial membrane potential (ΔΨm). Results of flow cytometry showed that DNICs were not affected the proliferation, growth of fibroblasts. In addition, this study showed that DNICs did not affect glutathione levels and the formation of reactive oxygen species in cells. Moreover, results indicated that DNICs maintained the ATP equilibrium in cells. Taken together, these findings show that DNICs have protective properties in vitro. It was further suggested that DNICs may be uncouplers of oxidative phosphorylation in mitochondria and protective mechanism is mainly provided by the leakage of excess charge through the mitochondrial membrane. It is assumed that the DNICs have the therapeutic potential for treating cardiovascular diseases and for decreasing of chemotherapy-induced cardiotoxicity in cancer survivors.

The cytokine alterations/abnormalities and oxidative damage in the pancreas during hypertension development

The aim of the present study was to compare the content of cytokines, chemokines, and oxidative stress markers in the pancreas of spontaneously hypertensive rats (SHRs) and Wistar Kyoto Rats (WKYs) serving as controls. Enzyme-like immunosorbent assay (ELISA) and biochemical methods were used to measure pancreatic levels of interleukin-1ß, interleukin-6, tumor necrosis factor α, transforming growth factor β, RANES, monocyte chemoattractant protein 1, interferon gamma-induced protein 10, malondialdehyde, and sulfhydryl groups. The results showed that the pancreatic concentrations of all studied cytokines and chemokines did not differ between 5-week-old SHRs and WKYs, except RANTES which was significantly reduced in juvenile SHRs. In 10-week-old animals, except interleukin-1ß, the levels of all these proteins were significantly reduced in SHRs. The pancreatic levels of malondialdehyde were significantly reduced in 5-week-old SHRs and significantly elevated in 10-week-old SHRs while the contents of sulfhydryl groups were similar in both rat strains at any age studied. In conclusion, these data provide evidence that in maturating SHRs, the pancreatic levels of cytokines and chemokines are significantly reduced, while malondialdehyde significantly elevated. This suggests that in the pancreas of mature SHRs, the inflammation process is suppressed but there is ongoing oxidative damage.

Considerations of the importance of redox state for reactive nitrogen species action

Nitric oxide (NO) and other reactive nitrogen species (RNS) are immensely important signalling molecules in plants, being involved in a range of physiological responses. However, the exact way in which NO fits into signal transduction pathways is not always easy to understand. Here, some of the issues that should be considered are discussed. This includes how NO may interact directly with other reactive signals, such as reactive oxygen and sulfur species, how NO metabolism is almost certainly compartmentalized, that threshold levels of RNS may need to be reached to have effects, and how the intracellular redox environment may impact on NO signalling. Until better tools are available to understand how NO is generated in cells, where it accumulates, and to what levels it reaches, it will be hard to get a full understanding of NO signalling. The interaction of RNS metabolism with the intracellular redox environment needs further investigation. A changing redox poise will impact on whether RNS species can thrive in or around cells. Such mechanisms will determine whether specific RNS can indeed control the responses needed by a cell.

The glutathione system and the related thiol network in Caenorhabditis elegans

Advances in the field of redox biology have contributed to the understanding of the complexity of the thiol-based system in mediating signal transduction. The redox environment is the overall spatiotemporal balance of oxidation-reduction systems within the integrated compartments of the cell, tissues and whole organisms. The ratio of the reduced to disulfide glutathione redox couple (GSH:GSSG) is a key indicator of the redox environment and its associated cellular health. The reaction mechanisms of glutathione-dependent and related thiol-based enzymes play a fundamental role in the function of GSH as a redox regulator. Glutathione homeostasis is maintained by the balance of GSH synthesis (de novo and salvage pathways) and its utilization through its detoxification, thiol signalling, and antioxidant defence functions via GSH-dependent enzymes and free radical scavenging. As such, GSH acts in concert with the entire redox network to maintain reducing conditions in the cell. Caenorhabditis elegans offers a simple model to facilitate further understanding at the multicellular level of the physiological functions of GSH and the GSH-dependent redox network. This review discusses the C. elegans studies that have investigated glutathione and related systems of the redox network including; orthologs to the protein-encoding genes of GSH synthesis; glutathione peroxidases; glutathione-S-transferases; and the glutaredoxin, thioredoxin and peroxiredoxin systems.

Equations to Support Redox Experimentation

Working with redox compounds needs to take into account the oxidation and reduction state of the compound under study. This redox state can be influenced by the media in which the compound is found, but will also be influenced by local environments. For example, this may be dictated perhaps by the locality of amino acids in the three dimensional structure of a protein. Therefore, historically, equations have been developed to enable either the redox poise of the environment to be determined, or the redox state of the compound of interest. If a compound is found in the wrong redox state-perhaps inactive-in a cell this has significant ramifications for its role, for example in cell signaling. Here, the use of such equations is discussed, with examples of the relevance to modern redox biology.

Healthy brain aging: Interplay between reactive species, inflammation and energy supply

Brains' high energy expenditure with preferable utilization of glucose and ketone bodies, defines the specific features of its energy homeostasis. The extensive oxidative metabolism is accompanied by a concomitant generation of high amounts of reactive oxygen, nitrogen, and carbonyl species, which will be here collectively referred to as RONCS. Such metabolism in combination with high content of polyunsaturated fatty acids creates specific problems in maintaining brains' redox homeostasis. While the levels of products of interaction between RONCS and cellular components increase slowly during the first two trimesters of individuals' life, their increase is substantially accelerated towards the end of life. Here we review the main mechanisms controlling the redox homeostasis of the mammalian brain, their age-dependencies as well as their adaptive potential, which might turn out to be much higher than initially assumed. According to recent data, the organism seems to respond to the enhancement of aging-related toxicity by forming a new homeostatic set point. Therefore, further research will focus on understanding the properties of the new set point(s), the general nature of this phenomenon and will explore the limits of brains' adaptivity.

Hepatocyte Hyperproliferation upon Liver-Specific Co-disruption of Thioredoxin-1, Thioredoxin Reductase-1, and Glutathione Reductase

Energetic nutrients are oxidized to sustain high intracellular NADPH/NADP⁺ ratios. NADPH-dependent reduction of thioredoxin-1 (Trx1) disulfide and glutathione disulfide by thioredoxin reductase-1 (TrxR1) and glutathione reductase (Gsr), respectively, fuels antioxidant systems and deoxyribonucleotide synthesis. Mouse livers lacking both TrxR1 and Gsr sustain these essential activities using an NADPH-independent methionine-consuming pathway; however, it remains unclear how this reducing power is distributed. Here, we show that liver-specific co-disruption of the genes encoding Trx1, TrxR1, and Gsr (triple-null) causes dramatic hepatocyte hyperproliferation. Thus, even in the absence of Trx1, methionine-fueled glutathione production supports hepatocyte S phase deoxyribonucleotide production. Also, Trx1 in the absence of TrxR1 provides a survival advantage to cells under hyperglycemic stress, suggesting that glutathione, likely via glutaredoxins, can reduce Trx1 disulfide in vivo. In triple-null livers like in many cancers, deoxyribonucleotide synthesis places a critical yet relatively low-volume demand on these reductase systems, thereby favoring high hepatocyte turnover over sustained hepatocyte integrity.

Atherothrombosis and Oxidative Stress: Mechanisms and Management in Elderly

SIGNIFICANCE

The incidence of cardiovascular events (CVEs) increases with age, representing the main cause of death in an elderly population. Aging is associated with overproduction of reactive oxygen species (ROS), which may affect clotting and platelet activation, and impair endothelial function, thus predisposing elderly patients to thrombotic complications. Recent Advances: There is increasing evidence to suggest that aging is associated with an imbalance between oxidative stress and antioxidant status. Thus, upregulation of ROS-producing enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and myeloperoxidase, along with downregulation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase, occurs during aging. This imbalance may predispose to thrombosis by enhancing platelet and clotting activation and eliciting endothelial dysfunction. Recently, gut-derived products, such as trimethylamine N-oxide (TMAO) and lipopolysaccharide, are emerging as novel atherosclerotic risk factors, and gut microbiota composition has been shown to change by aging, and may concur with the increased cardiovascular risk in the elderly.

CRITICAL ISSUES

Antioxidant treatment is ineffective in patients at risk or with cardiovascular disease. Further, anti-thrombotic treatment seems to work less in the elderly population.

FUTURE DIRECTIONS

Interventional trials with antioxidants targeting enzymes implicated in aging-related atherothrombosis are warranted to explore whether modulation of redox status is effective in lowering CVEs in the elderly. Antioxid. Redox Signal. 27, 1083-1124.

Effect of a Fusion Peptide by Covalent Conjugation of a Mitochondrial Cell-Penetrating Peptide and a Glutathione Analog Peptide

Previously, we designed and synthesized a library of mitochondrial antioxidative cell-penetrating peptides (mtCPPs) superior to the parent peptide, SS31, to protect mitochondria from oxidative damage. A library of antioxidative glutathione analogs called glutathione peptides (UPFs), exceptional in hydroxyl radical elimination compared with glutathione, were also designed and synthesized. Here, a follow-up study is described, investigating the effects of the most promising members from both libraries on reactive oxidative species scavenging ability. None of the peptides influenced cell viability at the concentrations used. Fluorescence microscopy studies showed that the fluorescein-mtCPP1-UPF25 (mtgCPP) internalized into cells, and spectrofluorometric analysis determined the presence and extent of peptide into different cell compartments. mtgCPP has superior antioxidative activity compared with mtCPP1 and UPF25 against H₂O₂ insult, preventing ROS formation by 2- and 3-fold, respectively. Moreover, we neither observed effects on mitochondrial membrane potential nor production of ATP. These data indicate that mtgCPP is targeting mitochondria, protecting them from oxidative damage, while also being present in the cytosol. Our hypothesis is based on a synergistic effect resulting from the fused peptide. The mitochondrial peptide segment is targeting mitochondria, whereas the glutathione analog peptide segment is active in the cytosol, resulting in increased scavenging ability.

Redox signaling: An evolution from free radicals to aging

Redox biology has evolved from studies of the pathology that involves oxidants to an understanding of how oxidants participate in normal as well as aberrant signal transduction. Although the concept that signal transduction involved changes in the redox state dates from the 1930s, the modern history of redox biology began with the discovery of superoxide dismutase by McCord and Fridovich. The initial focus was on free radicals and damage of macromolecules, which remains an important topic. But, over time it was realized that hydroperoxides, especially H2O2 produced by NADPH oxidases, and electrophiles derived from lipid peroxidation or metabolism, played essential roles in physiologically relevant signaling. The mechanisms through which H2O2 and other electrophiles signal became an important area of study that provided insight into how these reactive molecules were involved in major signaling pathways and regulation of transcription factors. Thus, the field of redox signaling that is the overlap of signal transduction with redox biology was established. Alterations in redox signaling are observed in aging, but we also now know that redox signaling is essential in physiological homeostasis and that sustained deviation from redox homeostasis results in disease. This is a review of the history of redox biology from a personal perspective of nearly fifty years working in this field that hopefully provides some insights for the reader.