The Nrf2 cell defence pathway: Keap1-dependent and -independent mechanisms of regulation

Escherichia coli and Staphylococcus aureus Differentially Regulate Nrf2 Pathway in Bovine Mammary Epithelial Cells: Relation to Distinct Innate Immune Response

Escherichia coli and Staphylococcus aureus are major mastitis causing pathogens in dairy cattle but elicit distinct immune and an inflammatory response in the udder. However, the host determinants responsible for this difference remains largely unknown. Our initial studies focused on the global transcriptomic response of primary bovine mammary epithelial cells (pbMECs) to heat-killed E. coli and S. aureus. RNA-sequencing transcriptome analysis demonstrates a significant difference in expression profiles induced by E. coli compared with S. aureus. A major differential response was the activation of innate immune response by E. coli, but not by S. aureus. Interestingly, E. coli stimulation increased transcript abundance of several genes downstream of Nrf2 (nuclear factor erythroid 2-related factor 2) that were enriched in gene sets with a focus on metabolism and immune system. However, none of these genes was dysregulated by S. aureus. Western blot analysis confirms that S. aureus impairs Nrf2 activation as compared to E. coli. Using Nrf2-knockdown cells we demonstrate that Nrf2 is necessary for bpMECs to mount an effective innate defensive response. In support of this notion, nuclear Nrf2 overexpression augmented S. aureus-stimulated inflammatory response. We also show that, unlike E. coli, S. aureus disrupts the non-canonical p62/SQSTM1-Keap1 pathway responsible for Nrf2 activation through inhibiting p62/SQSTM1 phosphorylation at S349. Collectively, our findings provide important insights into the contribution of the Nrf2 pathway to the pathogen-species specific immune response in bovine mammary epithelial cells and raise a possibility that impairment of Nrf2 activation contributes to, at least in part, the weak inflammatory response in S. aureus mastitis.

Oxidative Stress, Mitochondrial Function and Adaptation to Exercise: New Perspectives in Nutrition

Cells have the ability to adapt to stressful environments as a part of their evolution. Physical exercise induces an increase of a demand for energy that must be met by mitochondria as the main (ATP) provider. However, this process leads to the increase of free radicals and the so-called reactive oxygen species (ROS), which are necessary for the maintenance of cell signaling and homeostasis. In addition, mitochondrial biogenesis is influenced by exercise in continuous crosstalk between the mitochondria and the nuclear genome. Excessive workloads may induce severe mitochondrial stress, resulting in oxidative damage. In this regard, the objective of this work was to provide a general overview of the molecular mechanisms involved in mitochondrial adaptation during exercise and to understand if some nutrients such as antioxidants may be implicated in blunt adaptation and/or an impact on the performance of exercise by different means.

Mitochondrial Management of Reactive Oxygen Species

Mitochondria in aerobic eukaryotic cells are both the site of energy production and the formation of harmful species, such as radicals and other reactive oxygen species, known as ROS. They contain an efficient antioxidant system, including low-molecular-mass molecules and enzymes that specialize in removing various types of ROS or repairing the oxidative damage of biological molecules. Under normal conditions, ROS production is low, and mitochondria, which are their primary target, are slightly damaged in a similar way to other cellular compartments, since the ROS released by the mitochondria into the cytosol are negligible. As the mitochondrial generation of ROS increases, they can deactivate components of the respiratory chain and enzymes of the Krebs cycle, and mitochondria release a high amount of ROS that damage cellular structures. More recently, the feature of the mitochondrial antioxidant system, which does not specifically deal with intramitochondrial ROS, was discovered. Indeed, the mitochondrial antioxidant system detoxifies exogenous ROS species at the expense of reducing the equivalents generated in mitochondria. Thus, mitochondria are also a sink of ROS. These observations highlight the importance of the mitochondrial antioxidant system, which should be considered in our understanding of ROS-regulated processes. These processes include cell signaling and the progression of metabolic and neurodegenerative disease.

Silent information regulator 1 ameliorates oxidative stress injury via PGC-1α/PPARγ-Nrf2 pathway after ischemic stroke in rat

OBJECTIVE

Astrocytes mediate brain defense against oxidative stress-induced injury. Silent information regulator 1 (SIRT1) has anti-oxidative stress effects in many diseases and is highly expressed in astrocytes. However, the neuroprotective effects of SIRT1 on astrocytes after cerebral ischemia/reperfusion injury are unclear. Therein, we aim to investigate the protective effect of SIRT1 on oxidative stress injury after ischemic stroke and possible mechanisms.

METHODS

We evaluated the effects of SIRT1 in astrocytes after cerebral ischemia/reperfusion injury using oxygen-glucose deprivation/recovery (OGD/R) in astrocytes in vitro and middle cerebral artery occlusion in rats in vivo. siRNA was injected intracerebroventricularly 24 h before Middle cerebral artery (MCA) occlusion (MCAO)/reperfusion(R) to silence SIRT1.

RESULTS

SIRT1 knockdown reduced cell viability, increased oxidative stress, and decreased PGC-1α, PPARγ, Nrf2, heme oxygenase (HO)-1, and NAD(P)H: oxidoreductase-1 (NQO1) expression. Moreover, SIRT1 knockdown also suppressed PGC-1α activity, the PGC-1α/PPARγ interaction, and the PPARγ/PPRE interaction. Similarly, in our in vivo experiments, SIRT1 overexpression and PGC-1α or PPARγ knockdown reduced PGC-1α, PPARγ, Nrf2, HO-1, and NQO1 protein expression and blocked the PGC-1α/PPARγ interaction. SIRT1 overexpression plus PPARγ knockdown inhibited the interaction of PPARγ with PPRE. Nrf2 knockdown blocked Nrf2 expression and downstream proteins induced by SIRT1 overexpression.

CONCLUSION

Overall, our data indicated that SIRT1 directly mediated the PGC-1α/PPARγ pathway in response to focal cerebral ischemia/reperfusion-induced neurological deficit, providing insights into the treatment of focal cerebral ischemia/reperfusion injury.

MnTnHex-2-PyP5+, Coupled to Radiation, Suppresses Metastasis of 4T1 and MDA-MB-231 Breast Cancer via AKT/Snail/EMT Pathways

Tumor migration and invasion induced by the epithelial-to-mesenchymal transition (EMT) are prerequisites for metastasis. Here, we investigated the inhibitory effect of a mimic of superoxide dismutase (SOD), cationic Mn(III) ortho-substituted N-n-hexylpyridylporphyrin (MnTnHex-2-PyP⁵⁺, MnHex) on the metastasis of breast cancer in cellular and animal models, focusing on the migration of tumor cells and the factors that modulate this behavior. Wound healing and Transwell migration assays revealed that the migration of mouse mammary carcinoma 4T1 cells was markedly reduced during the concurrent treatment of MnHex and radiation therapy (RT) compared with that of the control and RT alone. Bioluminescence imaging showed that MnHex/RT co-treatment dramatically reduced lung metastasis of 4T1 cells in mice, compared with the sham control and both single treatments. Western blotting and immunofluorescence showed that MnHex treatment of 4T1 cells reversed the RT-induced EMT via inhibiting AKT/GSK-3β/Snail pathway in vitro, thereby decreasing cell migration and invasion. Consistently, histopathological analyses of 4T1 tumors showed that MnHex/RT reduced Snail expression, blocked EMT, and in turn suppressed metastases. Again, in the human metastatic breast cancer MDA-MB-231 cell line, MnHex inhibited metastatic potential in vitro and in vivo and suppressed the RT-induced Snail expression. In addition to our previous studies showing tumor growth inhibition, this study demonstrated that MnHex carries the ability to minimize the metastatic potential of RT-treated cancers, thus overcoming their radioresistance.

NRF2 activation inhibits valproic acid-induced neural tube defects in mice

Valproic acid (VPA) is a widely prescribed medication that has traditionally been used to treat epilepsy, yet embryonic exposure to VPA increases the risk of the fetus developing neural tube defects (NTDs). While the mechanism by which VPA causes NTDs is unknown, we hypothesize that VPA causes dysmorphogenesis through the disruption of redox-sensitive signaling pathways that are critical for proper embryonic development, and that protection from the redox disruption may decrease the prevalence of NTDs. Time-bred CD-1 mice were treated with 3H-1,2-dithiole-3-thione (D3T), an inducer of nuclear factor erythroid 2-related factor 2 (NRF2)-a transcription factor that activates the intracellular antioxidant response to prevent redox disruptions. Embryos were then collected for whole embryo culture and subsequently treated with VPA in vitro. The glutathione (GSH)/glutathione disulfide (GSSG) redox potential (E_h), a measure of the intracellular redox environment, was measured in the developing mouse embryos. Embryos treated with VPA exhibited a transiently oxidizing GSH/GSSG E_h, while those that received D3T pretreatment prior to VPA exposure showed no differences compared to controls. Moving to an in utero mouse model, time-bred C57BL/6 J dams were pretreated with or without D3T and then exposed to VPA, after which all embryos were collected for morphological analyses. The prevalence of open neural tubes in embryos treated with VPA significantly decreased with D3T pretreatment, as did the severity of the observed defects evaluated by a morphological assessment. These data show that NRF2 induction via D3T pretreatment protects against VPA-induced redox dysregulation and decreases the prevalence of NTDs in developing mouse embryos.

BTT-105 ameliorates hepatic fibrosis in non-alcoholic fatty liver animal model

BTT-105 (1-O-hexyl-2,3,5-trimethylhydroquinone), a hydroquinone derivative, is a potent anti-oxidant that was safe and tolerable in phase I clinical trial. This study examined the anti-fibrotic effect of BTT-105 in a mouse model of non-alcoholic fatty liver disease (NAFLD) along with the underlying mechanisms. In vivo, efficacy of BTT-105 evaluated from three kinds of NAFLD models (methionine/choline deficient diet (MCD), high fat diet (HF) and western diet (WD)). Metabolomics and transcriptomics profiling analysis in liver tissues were conducted. In vitro, anti-fibrotic effect of BTT-105 assessed in human hepatic stellated cells (HSCs) and primary mouse HSCs. BTT-105 improved NAFLD activity score in three kinds of NAFLD animal models (MCD, HF, and WD). BTT-105 also decreased levels of hepatic pro-collagen and collagen fibers deposition in liver tissue. Metabolome and transcriptome analysis revealed that BTT-105 decreased lipid metabolites and increased antioxidants in NAFLD mice. In HepG2 cells, BTT-105 enhanced Nrf2-ARE reporter activity in a dose-dependent manner and increased the levels of antioxidant gene expression. BTT-105 showed inhibition of HSCs activation and migration. Gene expression profiling and protein expression showed that BTT-105 increased Nrf2 activation as well as decreased PI3K-Akt pathway in activated HSCs. BTT-105 attenuated ameliorates steatohepatitis and hepatic fibrosis.

Impaired antioxidant KEAP1-NRF2 system in amyotrophic lateral sclerosis: NRF2 activation as a potential therapeutic strategy

BACKGROUND

Oxidative stress (OS) is an imbalance between oxidant and antioxidant species and, together with other numerous pathological mechanisms, leads to the degeneration and death of motor neurons (MNs) in amyotrophic lateral sclerosis (ALS).

MAIN BODY

Two of the main players in the molecular and cellular response to OS are NRF2, the transcription nuclear factor erythroid 2-related factor 2, and its principal negative regulator, KEAP1, Kelch-like ECH (erythroid cell-derived protein with CNC homology)-associated protein 1. Here we first provide an overview of the structural organization, regulation, and critical role of the KEAP1-NRF2 system in counteracting OS, with a focus on its alteration in ALS. We then examine several compounds capable of promoting NRF2 activity thereby inducing cytoprotective effects, and which are currently in different stages of clinical development for many pathologies, including neurodegenerative diseases.

CONCLUSIONS

Although challenges associated with some of these compounds remain, important advances have been made in the development of safer and more effective drugs that could actually represent a breakthrough for fatal degenerative diseases such as ALS.

Advanced preclinical models for evaluation of drug-induced liver injury - consensus statement by the European Drug-Induced Liver Injury Network [PRO-EURO-DILI-NET]

Drug-induced liver injury (DILI) is a major cause of acute liver failure (ALF) and one of the leading indications for liver transplantation in Western societies. Given the wide use of both prescribed and over the counter drugs, DILI has become a major health issue for which there is a pressing need to find novel and effective therapies. Although significant progress has been made in understanding the molecular mechanisms underlying DILI, our incomplete knowledge of its pathogenesis and inability to predict DILI is largely due to both discordance between human and animal DILI in preclinical drug development and a lack of models that faithfully recapitulate complex pathophysiological features of human DILI. This is exemplified by the hepatotoxicity of acetaminophen (APAP) overdose, a major cause of ALF because of its extensive worldwide use as an analgesic. Despite intensive efforts utilising current animal and in vitro models, the mechanisms involved in the hepatotoxicity of APAP are still not fully understood. In this expert Consensus Statement, which is endorsed by the European Drug-Induced Liver Injury Network, we aim to facilitate and outline clinically impactful discoveries by detailing the requirements for more realistic human-based systems to assess hepatotoxicity and guide future drug safety testing. We present novel insights and discuss major players in APAP pathophysiology, and describe emerging in vitro and in vivo pre-clinical models, as well as advanced imaging and in silico technologies, which may improve prediction of clinical outcomes of DILI.

Inhibition of Nrf2-mediated glucose metabolism by brusatol synergistically sensitizes acute myeloid leukemia to Ara-C

Chemotherapy resistance remains to be the primary barrier to acute myeloid leukemia (AML) treatment failure. Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been well established as a truly pleiotropic transcription factor. Inhibition of Nrf2 function increases the sensitivity of various chemotherapeutics and overcomes chemoresistance effectively. Brusatol (Bru) has been reported to decrease Nrf2 protein expression specifically by ubiquitin degradation of Nrf2. However, it remains elusive whether combination of Brusatol and Cytarabine (Ara-C) elicits a synergistic antitumor effect in AML. Our results demonstrated that combination of Ara-C and Brusatol synergistically exerted remarkable pro-apoptosis effect in HL-60 and THP-1 cells. Mechanistically, synergistic anti-tumor effect of Ara-C/Brusatol in AML cells is mediated by attenuating Nrf2 expression. To our surprise, Nrf2 inhibition by Brusatol causes downregulation of the expression of glycolysis-related proteins and decreased glucose consumption and lactate production, whereas the level of ROS production was unaffected. The activation of Nrf2 by Sulforaphane (SFP) could reverse the chemotherapeutic effect and changes of glycolysis of concomitant of Ara-C with Brusatol in AML cell lines. Additionally, Ara-C/Brusatol co-treatment decreased Glucose-6-phosphate dehydrogenase (G6PD) protein expression and increased the sensitivity of Ara-C. Moreover, the mouse xenograft in vivo experiment confirmed that combining Ara-C with Brusatol exerted stronger antileukemia than Ara-C alone. The efficacy, together with the mechanistic observations, reveals the potential of simultaneously giving these two drugs and provides a rational basis for targeting glucose catabolism in future clinical therapeutic approach.

Aging disrupts the temporal organization of antioxidant defenses in the heart of male rats and phase shifts circadian rhythms of systolic blood pressure

Aging is one of the main risk factors for cardiovascular diseases, and oxidative stress is a key element responsible for the development of age-related pathologies. In addition, the alteration of circadian rhythms also contributes to cardiovascular pathology, but the underlying mechanisms are not well defined. We investigated the aging consequences on the temporal patterns of antioxidant defenses, the molecular clock machinery, and the blood pressure, in the heart of male rats maintained under constant darkness (free running) conditions. Male Holtzman rats from young adult (3-month-old) and older (22-month-old) groups were maintained under constant darkness (12-h dark:12-h dark, DD) condition during fifteen days before the experiment. After the DD period, heart ventricle samples were isolated every 4-h throughout a 24-h period. We observed circadian rhythms of catalase (CAT) and glutathione peroxidase (GPx) mRNA expression, as well as ultradian rhythms of Nrf2 mRNA levels, in the heart of young adult rats. We also found circadian oscillations of CAT and GPx enzymatic activities, reduced glutathione (GSH) and BMAL1 protein in the same group. Interestingly, aging abolished the rhythms of CAT and GPx enzymatic activities, phase-shifted the rhythm's acrophases of GSH and BMAL1 protein levels and turned circadian the ultradian oscillation of Nrf2 expression. Moreover, aging phase-shifted the circadian pattern of systolic blood pressure. In conclusion, aging modifies the temporal organization of antioxidant defenses and blood pressure, probably, as a consequence of a disruption in the circadian rhythm of the clock's transcriptional regulator, BMAL1, in heart.

Liver disorders in COVID-19, nutritional approaches and the use of phytochemicals

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), has affected millions of people globally. It was declared a pandemic by the World Health Organization in March 2020. The hyperinflammatory response to the entry of SARS-CoV-2 into the host through angiotensin-converting enzyme 2 is the result of a "cytokine storm" and the high oxidative stress responsible for the associated symptomatology. Not only respiratory symptoms are reported, but gastrointestinal symptoms (diarrhea, vomiting, and nausea) and liver abnormalities (high levels of aspartate aminotransferase, alanine aminotransferase transaminases, and bilirubin) are observed in at least 30% of patients. Reduced food intake and a delay in medical services may lead to malnutrition, which increases mortality and poor outcomes. This review provides some strategies to identify malnutrition and establishes nutritional approaches for the management of COVID-19 and liver injury, taking energy and nutrient requirements and their impact on the immune response into account. The roles of certain phytochemicals in the prevention of the disease or as promising target drugs in the treatment of this disease are also considered.

Nrf2 and Heme Oxygenase-1 Involvement in Atherosclerosis Related Oxidative Stress

Atherosclerosis remains the underlying process responsible for cardiovascular diseases and the high mortality rates associated. This chronic inflammatory disease progresses with the formation of occlusive atherosclerotic plaques over the inner walls of vascular vessels, with oxidative stress being an important element of this pathology. Oxidation of low-density lipoproteins (ox-LDL) induces endothelial dysfunction, foam cell activation, and inflammatory response, resulting in the formation of fatty streaks in the atherosclerotic wall. With this in mind, different approaches aim to reduce oxidative damage as a strategy to tackle the progression of atherosclerosis. Special attention has been paid in recent years to the transcription factor Nrf2 and its downstream-regulated protein heme oxygenase-1 (HO-1), both known to provide protection against atherosclerotic injury. In the current review, we summarize the involvement of oxidative stress in atherosclerosis, focusing on the role that these antioxidant molecules exert, as well as the potential therapeutic strategies applied to enhance their antioxidant and antiatherogenic properties.

Bromophenol Bis (2,3,6-Tribromo-4,5-dihydroxybenzyl) Ether Protects HaCaT Skin Cells from Oxidative Damage via Nrf2-Mediated Pathways

Excessive reactive oxygen species (ROS) promotes the oxidative stress of keratinocytes, eventually causing cell damage. The natural bromophenol bis (2,3,6-tribromo-4,5-dihydroxybenzyl) ether (BTDE) from marine red algae has been reported to have a varied bioactivity; however, its antioxidant effect has yet to be investigated systemically. Our present work aimed to explore the antioxidant effect of BTDE both on the molecular and cellular models and also to illustrate the antioxidant mechanisms. Our results showed that BTDE could effectively scavenge ABTS free radicals and protect HaCaT cells from damage induced by H₂O₂. Mechanism studies in HaCaT cells demonstrated that BTDE attenuated hydrogen peroxide (H₂O₂)-induced ROS production, reduced the malondialdehyde (MDA) level, decreased the oxidized glutathione (GSSG)/glutathione (GSH) ratio, and increased the antioxidant enzyme superoxide dismutase (SOD). Moreover, BTDE could inhibit the expression of Kelch-like epichlorohydrin-associated protein 1 (Keap1) and increase the expression of both nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream proteins TrXR1, HO-1, and NQO1. BTDE also activated the upstream signaling pathway of Nrf2 such as AKT pathway, while not activating the ERK or AMPKα pathways. In general, BTDE is a promising antioxidant to protect HaCaT cells against oxidative damage via Nrf2-mediated pathways.

Induction of the antioxidant defense system using long-chain carotenoids extracted from extreme halophilic archaeon, Halovenus aranensis

The field of microbial pigments is an emerging area in natural products science. Carotenoids form a major class of such pigments and are found to be diversely synthesized by microorganisms that reside in hypersaline ecosystems to provide resistance against oxidative stress. Human cells can benefit from compounds such as carotenoids as antioxidant agents through either their capability to quench free radicals or their effect on promoting the antioxidant defense pathway. In this study, the antioxidant effectiveness of carotenoid extract from an extremely halophilic archaeon Halovenus aranensis strain EB27^T has been evaluated using different approaches. Finally, the ability of the extracted pigment to induce the antioxidant defense pathway of human primary skin fibroblast cells was studied. Hvn. aranensis carotenoid extract exhibited strong effectiveness such that at 2 µg/ml, the carotenoid extract fully neutralized the oxidative stress of hydrogen peroxide at its EC50 based on MTT assay. Results from real-time PCR of relevant genes, luciferase bioreporter of oxidative stress, and the western blot analysis further confirmed the antioxidant capability of the carotenoids. It was also shown the carotenoid extract had more antioxidant activity compared to β-carotene the same concentration. Results suggest the carotenoid extract from this archaeon to have high potential for clinical and industrial applications.

A Novel Nrf2 Pathway Inhibitor Sensitizes Keap1-Mutant Lung Cancer Cells to Chemotherapy

The nuclear factor erythroid-2-related factor 2 (Nrf2)-Keap1-ARE pathway, a master regulator of oxidative stress, has emerged as a promising target for cancer therapy. Mutations in NFE2L2, KEAP1, and related genes have been found in many human cancers, especially lung cancer. These mutations lead to constitutive activation of the Nrf2 pathway, which promotes proliferation of cancer cells and their resistance to chemotherapies. Small molecules that inhibit the Nrf2 pathway are needed to arrest tumor growth and overcome chemoresistance in Nrf2-addicted cancers. Here, we identified a novel small molecule, MSU38225, which can suppress Nrf2 pathway activity. MSU38225 downregulates Nrf2 transcriptional activity and decreases the expression of Nrf2 downstream targets, including NQO1, GCLC, GCLM, AKR1C2, and UGT1A6. MSU38225 strikingly decreases the protein level of Nrf2, which can be blocked by the proteasome inhibitor MG132. Ubiquitination of Nrf2 is enhanced following treatment with MSU38225. By inhibiting production of antioxidants, MSU38225 increases the level of reactive oxygen species (ROS) when cells are stimulated with tert-butyl hydroperoxide (tBHP). MSU38225 also inhibits the growth of human lung cancer cells in both two-dimensional cell culture and soft agar. Cancer cells addicted to Nrf2 are more susceptible to MSU38225 for suppression of cell proliferation. MSU38225 also sensitizes human lung cancer cells to chemotherapies both in vitro and in vivo Our results suggest that MSU38225 is a novel Nrf2 pathway inhibitor that could potentially serve as an adjuvant therapy to enhance the response to chemotherapies in patients with lung cancer.

Role of oxidative stress in pathophysiology of rheumatoid arthritis: insights into NRF2-KEAP1 signalling

Rheumatoid arthritis is one of the most prevalent, chronic, inflammatory disorders involving multiple articular and extra-articular complications. Immune deregulation owing to a combinatorial network of cells, inflammatory components, degrading enzymes, angiogenetic factors, exhibiting pleiotropy, synergy, or redundancy, is a critical hallmark for synovial inflammatory milieu reasoning clinical heterogeneity and variability of the disease. As a prototype of autoimmune disease, the pathophysiology of rheumatoid arthritis has been linked to oxidative stress. However, the exact mechanism for these potential driving factors contributing to disease inception and perpetuation is yet elusive. Nuclear factor erythroid 2-related factor 2 - Kelch ECH associating protein 1 (Nrf2-Keap1) pathway, controlled via multifactorial regulation, functions as a ubiquitous, evolutionarily conserved intracellular defense mechanism. Nrf2-Keap1 signalling maintains homeostatic responses against a plethora of environmental or endogenous deviations in cellular growth, death, redox metabolism, inflammation, bone remodelling, detoxification, etc. Administration of antioxidants as an add-on pharmacotherapy along with conventional drugs has been elucidated as a better measure for disease management. Some of the most promising natural and synthetic redox-based therapeutic compounds function as either scavengers of reactive species, or inhibitors of their sources, or activators of an endogenous antioxidant system (Nrf2-Keap1). The present review focuses on the binomial "rheumatoid arthritis-oxidative stress", bringing insights into their pathophysiological interrelationships and Nrf2 signalling, as well as the implications of potential diagnostic oxidative stress biomarkers and therapeutic interventions directed for disease management in patients with rheumatoid arthritis.Highlights:RA has complex etiopathogenesis, evolving from multiple endogenous and exogenous factors with oxidative stress as a critical pathogenic signature.Oxidative damage and damaged compounds could serve as potent biomarkers for disease diagnosis, therapeutic response, and prognosis.One of the supreme cytoprotective signalling cascades, the Nrf2-Keap1 pathway has been known to elicit a protective effect against RA and various other autoimmune, inflammatory, degenerative disorders.Inclusion of natural and synthetic antioxidants has been encouraged by various studies for additional therapy to conventional drugs for better management of the disease.

Chalcones: Synthetic Chemistry Follows Where Nature Leads

Chalcones belong to the flavonoid class of phenolic compounds. They form one of the largest groups of bioactive natural products. The potential anticancer, anti-inflammatory, antimicrobial, antioxidant, and antiparasitic properties of naturally occurring chalcones, and their unique chemical structural features inspired the synthesis of numerous chalcone derivatives. In fact, structural features of chalcones are easy to construct from simple aromatic compounds, and it is convenient to perform structural modifications to generate functionalized chalcone derivatives. Many of these synthetic analogs were shown to possess similar bioactivities as their natural counterparts, but often with an enhanced potency and reduced toxicity. This review article aims to demonstrate how bioinspired synthesis of chalcone derivatives can potentially introduce a new chemical space for exploitation for new drug discovery, justifying the title of this article. However, the focus remains on critical appraisal of synthesized chalcones and their derivatives for their bioactivities, linking to their interactions at the biomolecular level where appropriate, and revealing their possible mechanisms of action.

Carbofuran affects cellular autophagy and developmental senescence through the impairment of Nrf2 signalling

Carbofuran is a broad-spectrum synthetic pesticide. Its exposure to non-target mammals affects the biological system through the induction of oxidative stress. Since oxidative stress is a major contributing factor to cellular autophagy and senescence, our present investigation determined the impacts of carbofuran-induced oxidative stress on cellular autophagy and senescence. A transmembrane protein, Spinster homolog 1 (Spns1), is involved in autophagic lysosomal metabolism. Its mutation accelerates the cellular senescence and shortens the lifespan. Using a transgenic zebrafish line, expressing fluorescent microtubules-associated protein 1 light chain 3 (EGFP-LC3) at the membrane of the autophagosome, we found that carbofuran affects autophagic lysosomal biogenesis in wild-type zebrafish and exacerbates autophagic defect in spns1-mutant zebrafish. In real-time mortality study, carbofuran has shortened the lifespan of wild-type fish. Nrf2 is a stress-responsive transcription factor that regulates the expression of antioxidant genes (such as gstp1) in the prevention of oxidative stress-mediated cellular damage. To assess the effect of carbofuran on Nrf2 signalling, we established a dual-monitoring transgenic zebrafish line, expressing gstp1 promoter-driven EGFP and mCherry-tagged Neh2 domain of Nrf2. Our results suggested that the exposure of carbofuran has down-regulated both Nrf2 and Gstp1 expressions. Overall, carbofuran affects cellular autophagy and accelerates senescence by enervating the Nrf2 signalling.

The ketone body β-hydroxybutyrate mitigates the senescence response of glomerular podocytes to diabetic insults

Diabetic kidney disease (DKD) is one of the most common complications of diabetes and clinically featured by progressive albuminuria, consequent to glomerular destruction that involves podocyte senescence. Burgeoning evidence suggests that ketosis, in particular β-hydroxybutyrate, exerts a beneficial effect on aging and on myriad metabolic or chronic diseases, including obesity, diabetes and chronic kidney diseases. Its effect on DKD is largely unknown. In vitro in podocytes exposed to a diabetic milieu, β-hydroxybutyrate treatment substantially mitigated cellular senescence and injury, as evidenced by reduced formation of γH2AX foci, reduced staining for senescence-associated-β-galactosidase activity, diminished expression of key mediators of senescence signaling like p16INK4A and p21, and preserved expression of synaptopodin. This beneficial action of β-hydroxybutyrate coincided with a reinforced transcription factor Nrf2 antioxidant response. Mechanistically, β-hydroxybutyrate inhibition of glycogen synthase kinase 3β (GSK3β), a convergent point for myriad signaling pathways regulating Nrf2 activity, seems to contribute. Indeed, trigonelline, a selective inhibitor of Nrf2, or ectopic expression of constitutively active mutant GSK3β abolished, whereas selective activation of Nrf2 was sufficient for the anti-senescent and podocyte protective effects of β-hydroxybutyrate. Moreover, molecular modeling and docking analysis revealed that β-hydroxybutyrate is able to directly target the ATP-binding pocket of GSK3β and thereby block its kinase activity. In murine models of streptozotocin-elicited DKD, β-hydroxybutyrate therapy inhibited GSK3β and reinforced Nrf2 activation in glomerular podocytes, resulting in lessened podocyte senescence and injury and improved diabetic glomerulopathy and albuminuria. Thus, our findings may pave the way for developing a β-hydroxybutyrate-based novel approach of therapeutic ketosis for treating DKD.

Effect of supplementation of medium with Bauhinia forficata recombinant lectins on expression of oxidative stress genes during in vitro maturation of bovine oocytes

The lectin of Bauhinia forficata (nBfL) is a protein able to bind reversibly to N-acetylgalactosamine, performing several functions and one of them is the antiproliferative activity in tumor cells, but its effects have not yet been evaluated in female gametes. The objective of the present study was to determine the additional effect of B. forficata recombinants lectins in the medium of maturation in vitro of bovine oocytes in expression of genes related to oxidative stress pathways. To get the proteins, the gene for this recombinant lectin (rBfL) and its truncated isoform (rtBfL) were cloned and expressed in Escherichia coli (E.coli). The oocytes obtained through follicular puncture were incubated in IVM medium for 24 h containing concentrations of 10 μg/mL, 50 μg/mL and 100 μg/mL of nBfL, rBfL and rtBfL, and a no treated group as a control. In the groups treated with the concentration of 100 μg / mL, the gene expression of genes involved in oxidative stress SOD2, CAT, GPX-1, GSR, NOS2 and apoptosis BAX, CASP3 were evaluated. The rtBfL increased the expression of the SOD2, GSR and NOS2 genes and all the tested lectins increased the expression of the CASP3 gene compared to the control group. These findings indicate that the tested concentrations of the B. forficata recombinants lectins probably influence the expression of oxidative stress genes and increase the expression of the apoptotic gene CASP3 during in vitro maturation of bovine oocytes.

Effects of Aqueous Dispersions of C60, C70 and Gd@C82 Fullerenes on Genes Involved in Oxidative Stress and Anti-Inflammatory Pathways

Background: Fullerenes and metallofullerenes can be considered promising nanopharmaceuticals themselves and as a basis for chemical modification. As reactive oxygen species homeostasis plays a vital role in cells, the study of their effect on genes involved in oxidative stress and anti-inflammatory responses are of particular importance. Methods: Human fetal lung fibroblasts were incubated with aqueous dispersions of C₆₀, C₇₀, and Gd@C₈₂ in concentrations of 5 nM and 1.5 µM for 1, 3, 24, and 72 h. Cell viability, intracellular ROS, NOX4, NFκB, PRAR-γ, NRF2, heme oxygenase 1, and NAD(P)H quinone dehydrogenase 1 expression have been studied. Results & conclusion: The aqueous dispersions of C₆₀, C₇₀, and Gd@C₈₂ fullerenes are active participants in reactive oxygen species (ROS) homeostasis. Low and high concentrations of aqueous fullerene dispersions (AFD) have similar effects. C₇₀ was the most inert substance, C₆₀ was the most active substance. All AFDs have both “prooxidant” and “antioxidant” effects but with a different balance. Gd@C₈₂ was a substance with more pronounced antioxidant and anti-inflammatory properties, while C₇₀ had more pronounced “prooxidant” properties.

α-Synuclein pathology in Parkinson disease activates homeostatic NRF2 anti-oxidant response

Circumstantial evidence points to a pathological role of alpha-synuclein (aSyn; gene symbol SNCA), conferred by aSyn misfolding and aggregation, in Parkinson disease (PD) and related synucleinopathies. Several findings in experimental models implicate perturbations in the tissue homeostatic mechanisms triggered by pathological aSyn accumulation, including impaired redox homeostasis, as significant contributors in the pathogenesis of PD. The nuclear factor erythroid 2-related factor (NRF2/Nrf2) is recognized as ‘the master regulator of cellular anti-oxidant response’, both under physiological as well as in pathological conditions. Using immunohistochemical analyses, we show a robust nuclear NRF2 accumulation in post-mortem PD midbrain, detected by NRF2 phosphorylation on the serine residue 40 (nuclear active p-NRF2, S40). Curated gene expression analyses of four independent publicly available microarray datasets revealed considerable alterations in NRF2-responsive genes in the disease affected regions in PD, including substantia nigra, dorsal motor nucleus of vagus, locus coeruleus and globus pallidus. To further examine the putative role of pathological aSyn accumulation on nuclear NRF2 response, we employed a transgenic mouse model of synucleionopathy (M83 line, expressing the mutant human A53T aSyn), which manifests widespread aSyn pathology (phosphorylated aSyn; S129) in the nervous system following intramuscular inoculation of exogenous fibrillar aSyn. We observed strong immunodetection of nuclear NRF2 in neuronal populations harboring p-aSyn (S129), and found an aberrant anti-oxidant and inflammatory gene response in the affected neuraxis. Taken together, our data support the notion that pathological aSyn accumulation impairs the redox homeostasis in nervous system, and boosting neuronal anti-oxidant response is potentially a promising approach to mitigate neurodegeneration in PD and related diseases.

Enhanced NRF2 expression mitigates the decline in neural stem cell function during aging

Although it is known that aging affects neural stem progenitor cell (NSPC) biology in fundamental ways, the underlying dynamics of this process are not fully understood. Our previous work identified a specific critical period (CP) of decline in NSPC activity and function during middle age (13–15 months), and revealed the reduced expression of the redox‐sensitive transcription factor, NRF2, as a key mediator of this process. Here, we investigated whether augmenting NRF2 expression could potentially mitigate the NSPC decline across the identified CP. NRF2 expression in subventricular zone (SVZ) NSPCs was upregulated via GFP tagged recombinant adeno‐associated viral vectors (AAV‐NRF2‐eGFP), and its cellular and behavioral effects compared to animals that received control vectors (AAV‐eGFP). The vectors were administered into the SVZs of aging rats, at time points either before or after the CP. Results indicate that animals that had received AAV‐NRF2‐eGFP, prior to the CP (11 months of age), exhibited substantially improved behavioral function (fine olfactory discrimination and motor tasks) in comparison to those receiving control viruses. Further analysis revealed that NSPC proliferation, self‐renewal, neurogenesis, and migration to the olfactory bulb had significantly increased upon NRF2 upregulation. On the other hand, increasing NRF2 after the CP (at 20 months of age) produced no notable changes in NSPC activity at either cellular or behavioral levels. These results, for the first time, indicate NRF2 pathway modulation as a means to support NSPC function with age and highlight a critical time‐dependency for activating NRF2 to enhance NSPC function.

Spleen tyrosine kinase regulates crosstalk of hypoxia-inducible factor-1α and nuclear factor (erythroid-derived2)-like 2 for B cell survival

B cells play a major role in regulating disease incidence through various factors, including spleen tyrosine kinase (Syk), which transmits signals to all hematopoietic lineage cells. Hypoxia-inducible factor (HIF)-1α accumulates under hypoxic conditions, which is also oxidative stress to induce nuclear factor (erythroid-derived 2)-like 2 (Nrf2) responsible for gene expression of antioxidant enzymes. In the present study, we investigated whether B cells are regulated by crosstalk of HIF-1α and Nrf2 via reactive oxygen species (ROS)-mediated Syk activation. When B cells were incubated under hypoxic conditions, Syk phosphorylation, HIF-1α, and Nrf2 levels were increased. Hypoxia-inducible results were consistent with CoCl2 treatment, which mimics hypoxic conditions. Cell viability was reduced by the Syk inhibitor BAY 61-3606. Increased Nrf2 levels due to hypoxia or CoCl2 were inhibited by treatment with a HIF inhibitor. Hypoxia- or CoCl2-induced ROS increased HIF-1α and Nrf2 levels, which were attenuated by treatment with N-acetyl-L-cysteine (NAC), a ROS scavenger. HIF-1α levels were reduced in doxycycline-treated shNrf2 cells. Clobetasol propionate, a Nrf2 inhibitor, also inhibited HIF-1α levels induced by hypoxia or CoCl2. ROS-mediated Syk phosphorylation at tyrosine 525/526 was confirmed by treatment with H2O2, hypoxia, and CoCl2, and attenuated with NAC treatment. Inhibition of Syk phosphorylation by BAY 61-3606 is consistent with a decrease in protein HIF-1α and Nrf2 levels. Taken together, HIF-1α levels might control Nrf2 levels and vice versa, and could be associated with Syk phosphorylation in B cells. The results indicate that B cells could be regulated by crosstalk of HIF-1α and Nrf2 through ROS-mediated Syk activation.

Retinal oxidative stress activates the NRF2/ARE pathway: An early endogenous protective response to ocular hypertension

Oxidative stress contributes to degeneration of retinal ganglion cells and their axons in glaucoma, a leading cause of irreversible blindness worldwide, through sensitivity to intraocular pressure (IOP). Here, we investigated early elevations in reactive oxygen species (ROS) and a role for the NRF2-KEAP1-ARE endogenous antioxidant response pathway using microbead occlusion to elevate IOP in mice. ROS levels peaked in the retina at 1- and 2-wks following IOP elevation and remained elevated out to 5-wks. Phosphorylation of NRF2 and antioxidant gene transcription and protein levels increased concomitantly at 2-wks after IOP elevation, along with phosphorylation of PI3K and AKT. Inhibiting PI3K or AKT signaling prevented NRF2 phosphorylation and reduced transcription of antioxidant-regulated genes. Ocular hypertensive mice lacking Nrf2 had elevated ROS and a diminished increase in antioxidant gene expression. They also exhibited earlier axon degeneration and loss of visual function. In conclusion, the NRF2-KEAP1-ARE pathway is endogenously activated early in ocular hypertension due to phosphorylation of NRF2 by the PI3K/AKT pathway and serves to slow the onset of axon degeneration and vision loss in glaucoma. These data suggest that exogenous activation of this pathway might further slow glaucomatous neurodegeneration.

Phelligridin D from Inonotus obliquus attenuates oxidative stress and accumulation of ECM in mesangial cells under high glucose via activating Nrf2

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes mellitus and becomes the financial burden and health problem. Pathogenesis of DN has revealed that high glucose has resulted in the oxidative stress and accumulation of extracellular matrix (ECM). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor regulating the expression of anti-oxidant enzymes. Therefore, activating Nrf2 gives a promising approach for the treatment of DN. In the discovery of bioactive phytochemicals targeting DN, we have identified phelligridin D from Inonotus obliquus and explored its protective effects against oxidative stress and accumulation of ECM using mesangial cells under high glucose and potential mechanisms. In addition to inhibiting the self-limited proliferation of mesangial cells cultured in high glucose, phelligridin D can attenuate oxidative stress through reducing reactive oxygen species (ROS) and malondialdehyde (MDA) as well as elevating the activity of superoxide dismutase (SOD) and catalase (CAT). Meanwhile, the major components of ECM including collagen IV, fibronectin and laminin were decreased by phelligridin D via inhibiting the secretion of transforming growth factor-β₁ (TGF-β₁) and downstream connective tissue growth factor (CTGF). Further investigations have revealed phelligridin D activated Nrf2 in mesangial cells under high glucose, which was involved in its protective effects. These findings can provide evidences for the discovery of novel therapy targeting DN and application of I. obliquus in practice.

Roles of Nrf2 in Gastric Cancer: Targeting for Therapeutic Strategies

Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) is a specific transcription factor with potent effects on the regulation of antioxidant gene expression that modulates cell hemostasis under various conditions in tissues. However, the effects of Nrf2 on gastric cancer (GC) are not fully elucidated and understood. Evidence suggests that uncontrolled Nrf2 expression and activation has been observed more frequently in malignant tumors, including GC cells, which is then associated with increased antioxidant capacity, chemoresistance, and poor clinical prognosis. Moreover, Nrf2 inhibitors and the associated modulation of tumor cell redox balance have shown that Nrf2 also has beneficial effects on the therapy of various cancers, including GC. Based on previous findings on the important role of Nrf2 in GC therapy, it is of great interest to scientists in basic and clinical tumor research that Nrf2 can be active as both an oncogene and a tumor suppressor depending on different background situations.

Hepatic Nfe2l2 Is Not an Essential Mediator of the Metabolic Phenotype Produced by Dietary Methionine Restriction

The principal sensing of dietary methionine restriction (MR) occurs in the liver, where it activates multiple transcriptional programs that mediate various biological components of the response. Hepatic Fgf21 is a key target and essential endocrine mediator of the metabolic phenotype produced by dietary MR. The transcription factor, Nfe2l2, is also activated by MR and functions in tandem with hepatic Atf4 to transactivate multiple, antioxidative components of the integrated stress response. However, it is unclear whether the transcriptional responses linked to Nfe2l2 activation by dietary MR are essential to the biological efficacy of the diet. Using mice with liver-specific deletion of Nfe2l2 (Nfe2l2^fl/(Alb)) and their floxed littermates (Nfe2l2^fl/fl) fed either Control or MR diets, the absence of hepatic Nfe2l2 had no effect on the ability of the MR diet to increase FGF21, reduce body weight and adiposity, and increase energy expenditure. Moreover, the primary elements of the hepatic transcriptome were similarly affected by MR in both genotypes, with the only major differences occurring in induction of the P450-associated drug metabolism pathway and the pentose glucuronate interconversion pathway. The biological significance of these pathways is uncertain but we conclude that hepatic Nfe2l2 is not essential in mediating the metabolic effects of dietary MR.

Endocannabinoid System and Its Regulation by Polyunsaturated Fatty Acids and Full Spectrum Hemp Oils

The endocannabinoid system (ECS) consists of endogenous cannabinoids, their receptors, and metabolic enzymes that play a critical homeostatic role in modulating polyunsaturated omega fatty acid (PUFA) signaling to maintain a balanced inflammatory and redox state. Whole food-based diets and dietary interventions linked to PUFAs of animal (fish, calamari, krill) or plant (hemp, flax, walnut, algae) origin, as well as full-spectrum hemp oils, are increasingly used to support the ECS tone, promote healthy metabolism, improve risk factors associated with cardiovascular disorders, encourage brain health and emotional well-being, and ameliorate inflammation. While hemp cannabinoids of THC and CBD groups show distinct but complementary actions through a variety of cannabinoid (CB1 and CB2), adenosine (A2A), and vanilloid (TRPV1) receptors, they also modulate PUFA metabolism within a wide variety of specialized lipid mediators that promote or resolve inflammation and oxidative stress. Clinical evidence reviewed in this study links PUFAs and cannabinoids to changes in ECS tone, immune function, metabolic and oxidative stress adaptation, and overall maintenance of a well-balanced systemic function of the body. Understanding how the body coordinates signals from the exogenous and endogenous ECS modulators is critical for discerning the underlying molecular mechanisms of the ECS tone in healthy and disease states. Nutritional and lifestyle interventions represent promising approaches to address chronic metabolic and inflammatory disorders that may overlap in the population at risk. Further investigation and validation of dietary interventions that modulate the ECS are required in order to devise clinically successful second-generation management strategies.

Regulation of Nrf2 by phosphorylation: Consequences for biological function and therapeutic implications

The transcription factor nuclear factor erythroid-derived 2-like 2 (NRF2) participates in the activation of the antioxidant cytoprotective pathway and other important physiological processes to maintain cellular homeostasis. The dysregulation of NRF2 activity plays a role in various diseases, such as cardiovascular diseases, neurodegenerative diseases, and cancer. Thus, NRF2 activity is tightly regulated through multiple mechanisms, among which phosphorylation by kinases is critical in the posttranslational regulation of NRF2. For instance, PKC, casein kinase 2, and AMP-activated kinase positively, while GSK-3 negatively regulates NRF2 activity through phosphorylation of different sites. Here, we provide an overview of the phosphorylation regulation pattern of NRF2 and discuss the therapeutic potential of interventions targeting NRF2 phosphorylation.

Alcoholic and Non-Alcoholic Liver Diseases: Promising Molecular Drug Targets and their Clinical Development

Alcoholic and non-alcoholic fatty liver diseases have become a serious concern worldwide. Both these liver diseases have an identical pathology, starting from simple steatosis to cirrhosis and, ultimately to hepatocellular carcinoma. Treatment options for alcoholic liver disease (ALD) are still the same as they were 50 years ago which include corticosteroids, pentoxifylline, antioxidants, nutritional support and abstinence; and for non-alcoholic fatty liver disease (NAFLD), weight loss, insulin sensitizers, lipid-lowering agents and anti-oxidants are the only treatment options. Despite broad research in understanding the disease pathophysiology, limited treatments are available for clinical use. Some therapeutic strategies based on targeting a specific molecule have been developed to lessen the consequences of disease and are under clinical investigation. Therefore, focus on multiple molecular targets will help develop an efficient therapeutic strategy. This review comprises a brief overview of the pathogenesis of ALD and NAFLD; recent molecular drug targets explored for ALD and NAFLD that may prove to be effective for multiple therapeutic regimens and also the clinical status of these promising drug targets for liver diseases.

The in vitro and in vivo depigmenting activity of pterostilbene through induction of autophagy in melanocytes and inhibition of UVA-irradiated α-MSH in keratinocytes via Nrf2-mediated antioxidant pathways

Pterostilbene (Pt) is a natural polyphenol found in blueberries and several grape varieties. Pt's pharmacological importance was well documented. Nevertheless, the depigmenting effects are not demonstrated. We evaluated the Pt's depigmenting effects through autophagy induction in B16F10 cells and inhibition of UVA (3 J/cm²)-irradiated α-MSH in keratinocyte HaCaT cells via Nrf2-mediated antioxidant pathways. Pt (2.5–5μM) attenuated ROS production and downregulated the POMC/α-MSH pathway in HaCaT cells. The conditioned medium-derived from UVA-irradiated HaCaT pretreated with Pt suppressed melanogenesis in B16F10 through MITF-CREB-tyrosinase pathway downregulation. Interestingly, Pt-induced HaCaT autophagy was revealed by enhanced LC3-II accumulation, p62/SQSTM1 activation, and AVO formation. Pt significantly decreased melanosome gp100 but increased LC3-II levels in HaCaT cells exposed to B16F10-derived melanin. Pt activated and facilitated the Nrf2 antioxidant pathway in HaCaT cells leading to increased HO-1, γ-GCLC, and NQO-1 antioxidant protein expression. ERK, AMPK, and ROS pathways mediate the Nrf2 activation. However, Nrf2 knockdown suppressed Pt's antioxidant ability leading to uncontrolled ROS and α-MSH levels after UVA-irradiation suggested the essentiality of the Nrf2 pathway. Moreover, in α-MSH-stimulated B16F10 cells, Pt (10–30 μM) downregulated the MC1R, MITF, tyrosinase, TRP-1/-2, and melanin expression. Further, Pt showed potent anti-melanogenic effects through autophagy induction mechanism in B16F10 cells, verified by increased LC3-II/p62 levels, AVO formation, and Beclin-1/Bcl-2 ratio, decreased ATG4B levels and PI3K/AKT/mTOR pathway. Transmission electron microscopy provided direct evidence by showing autophagosomes engulfing melanosomes following Pt treatment in α-MSH-stimulated B16F10 cells. Moreover, Pt-induced anti-melanogenic activity through the downregulation of CREB-MITF pathway-mediated TRP-1/-2, tyrosinase expressions, melanosome formation, and melanin synthesis was substantially reversed due to 3-MA (autophagy inhibitor) pretreatment or LC3 silencing in B16F10 cells. In vivo results also confirmed that Pt-inhibited tyrosinase expression/activity and endogenous pigmentation in the zebrafish model. Therefore, pterostilbene is a potent skin-whitening and antioxidant agent and could be used in skin-whitening formulations as a topical applicant.

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Pt inhibits ROS-mediated POMC/α-MSH pathway in UVA-irradiated HaCaT cells.

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Pt activates Nrf2-mediated HO-1, γ-GCLC, and NQO-1 expression in HaCaT cells.

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Pt-induces autophagy in B16F10 cells leading to melanogenesis inhibition.

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Pt-mediates anti-melanogenic mechanisms in α-MSH-stimulated B16F10 cells.

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Pt-inhibits tyrosinase expression and endogenous pigmentation in zebrafish model.

Pinocembrin-7-Methylether Protects SH-SY5Y Cells Against 6-Hydroxydopamine-Induced Neurotoxicity via Modulating Nrf2 Induction Through AKT and ERK Pathways

The present study aimed to evaluate the neuroprotective effects and underlying mechanisms of pinocembrin-7-methylether (PME), a natural bioflavonoid, in 6-hydroxydopamine (6-OHDA)-induced models of Parkinson's disease in vivo and in vitro. First, we found that PME decreased apoptosis in 6-OHDA-intoxicated SH-SY5Y cells. PME also blocked several 6-OHDA-induced mitochondrial apoptotic cascades, including loss of mitochondrial membrane potential, caspase 3 and PARP activation, and a decrease in the Bcl-2/Bax ratio. Also, PME suppressed 6-OHDA-induced oxidative stress while increasing antioxidant enzymatic activity. Further investigations indicated that PME significantly enhanced nuclear accumulation of Nrf2, improved ARE promoter activity, and upregulated HO-1 and NQO1 expression levels. In addition, siRNA-mediated Nrf2 knockdown abolished PME-induced anti-oxidative and anti-apoptotic effects. Interestingly, we found that PME promoted phosphorylation of AKT and ERK, whereas pharmacological inhibition of AKT or ERK pathways diminished PME-induced Nrf2 activation and protective actions. Moreover, PME attenuated 6-OHDA-induced loss of dopaminergic neurons and ameliorated locomotor deficiency in zebrafish, supporting the neuroprotective actions of PME in vivo. In summary, we found that PME conferred neuroprotection against 6-OHDA-induced neurotoxicity in PD models in vivo and in vitro. Taken together, our findings suggest that activation of Nrf2/ARE/HO-1 signaling cascades contributes to PME-induced anti-oxidative and neuroprotective actions, which are at least partially mediated by AKT and ERK pathways.

Identification of a Stable, Non-Canonically Regulated Nrf2 Form in Lung Cancer Cells

Nrf2 (nuclear factor erythroid 2 (NF-E2)-related factor 2) transcription factor is recognized for its pro-survival and cell protective role upon exposure to oxidative, chemical, or metabolic stresses. Nrf2 controls a number of cellular processes such as proliferation, differentiation, apoptosis, autophagy, lipid synthesis, and metabolism and glucose metabolism and is a target of activation in chronic diseases like diabetes, neurodegenerative, and inflammatory diseases. The dark side of Nrf2 is revealed when its regulation is imbalanced (e.g., via oncogene activation or mutations) and under such conditions constitutively active Nrf2 promotes cancerogenesis, metastasis, and radio- and chemoresistance. When there is no stress, Nrf2 is instantly degraded via Keap1-Cullin 3 (Cul3) pathway but despite this, cells exhibit a basal activation of Nrf2 target genes. It is yet not clear how Nrf2 maintains the expression of its targets under homeostatic conditions. Here, we found a stable 105 kDa Nrf2 form that is resistant to Keap1-Cul3-mediated degradation and translocates to the nucleus of lung cancer cells. RNA-Seq analysis indicate that it might originate from the exon 2 or exon 3-truncated transcripts. This stable 105 kDa Nrf2 form might help explain the constitutive activity of Nrf2 under normal cellular conditions.

Autophagy Controls Nrf2-Mediated Dichotomy in Pressure Overloaded Hearts

Burgeoning evidence has indicated that normal autophagy is required for nuclear factor erythroid 2-related factor (Nrf2)-mediated cardiac protection whereas autophagy inhibition turns on Nrf2-mediated myocardial damage and dysfunction in a setting of pressure overload (PO). However, such a concept remains to be fully established by a careful genetic interrogation in vivo. This study was designed to validate the hypothesis using a mouse model of PO-induced cardiomyopathy and heart failure, in which cardiac autophagy and/or Nrf2 activity are genetically inhibited. Myocardial autophagy inhibition was induced by cardiomyocyte-restricted (CR) knockout (KO) of autophagy related (Atg) 5 (CR-Atg5KO) in adult mice. CR-Atg5KO impaired cardiac adaptations while exacerbating cardiac maladaptive responses in the setting of PO. Notably, it also turned off Nrf2-mediated defense while switching on Nrf2-operated tissue damage in PO hearts. In addition, cardiac autophagy inhibition selectively inactivated extracellular signal regulated kinase (ERK), which coincided with increased nuclear accumulation of Nrf2 and decreased nuclear translocation of activated ERK in cardiomyocytes in PO hearts. Mechanistic investigation revealed that autophagy is required for the activation of ERK, which suppresses Nrf2-driven expression of angiotensinogen in cardiomyocytes. Taken together, these results provide direct evidence consolidating the notion that normal autophagy enables Nrf2-operated adaptation while switching off Nrf2-mediated maladaptive responses in PO hearts partly through suppressing Nrf2-driven angiotensinogen expression in cardiomyocytes.

Rotundic acid reduces LPS-induced acute lung injury in vitro and in vivo through regulating TLR4 dimer

Acute lung injury (ALI) is a serious clinical disease. Rotundic acid (RA), a natural ingredient isolated from Ilex rotunda Thunb, exhibits multiple pharmacological activities. However, RA's therapeutic effect and mechanism on ALI remain to be elucidated. The present study aimed to further clarify its regulating effects on inflammation in vitro and in vivo. Our results indicated that RA significantly inhibited the overproduction of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). RA decreased ROS production and calcium influx. In addition, RA inhibited the activation of PI3K, MAPK, and NF-κB pathways and enhanced the activity of nuclear factor E2-related factor 2 (Nrf2) signaling. The cellular thermal shift assay and docking results indicated that RA bind to TLR4 to block TLR4 dimerization. Furthermore, RA pretreatment effectively inhibited ear edema induced by xylene and LPS-induced endotoxin death and had a protective effect on LPS-induced ALI. Our findings collectively indicated that RA has anti-inflammatory effects, which may serve as a potential therapeutic option for pulmonary inflammation.

Fructose-1,6-bisphosphatase aggravates oxidative stress-induced apoptosis in asthma by suppressing the Nrf2 pathway

Asthma is a chronic airway disease that causes excessive inflammation, oxidative stress, mucus production and bronchial epithelial cell apoptosis. Fructose‐1,6‐bisphosphatase (Fbp1) is one of the rate‐limiting enzymes in gluconeogenesis and plays a critical role in several cancers. However, its role in inflammatory diseases, such as asthma, is unclear. Here, we examined the expression, function and mechanism of action of Fbp1 in asthma. Gene Expression Omnibus (GEO) data sets revealed that Fbp1 was overexpressed in a murine model of asthma and in interleukin (IL)‐4‐ or IL‐13‐stimulated bronchial epithelial cells. We confirmed the findings in an animal model as well as Beas‐2B and 16HBE cells. In vitro investigations revealed that silencing of Fbp1 reduced apoptosis and the proportion of cells in the G2/M phase, whereas overexpression led to increases. Fbp1 knock‐down inhibited oxidative stress by activating the nuclear factor erythroid 2‐related factor 2 (Nrf2) pathway, whereas Fbp1 overexpression aggravated oxidative stress by suppressingthe Nrf2 pathway. Moreover, the Nrf2 pathway inhibitor ML385 reversed the changes caused by Fbp1 inhibition in Beas‐2B and 16HBE cells. Collectively, our data indicate that Fbp1 aggravates oxidative stress‐induced apoptosis by suppressing Nrf2 signalling, substantiating its potential as a novel therapeutic target in asthma.

Nanodelivery of natural isothiocyanates as a cancer therapeutic

Natural isothiocyanates (ITCs) are phytochemicals abundant in cruciferous vegetables with the general structure, R-NCS. They are bioactive organosulfur compounds derived from the hydrolysis of glucosinolates by myrosinase. A significant number of isothiocyanates have been isolated from different plant sources that include broccoli, Brussels sprouts, cabbage, cauliflower, kale, mustard, wasabi, and watercress. Several ITCs have been demonstrated to possess significant pharmacological properties including: antioxidant, anti-inflammatory, anti-cancer and antimicrobial activities. Due to their chemopreventive effects on many types of cancer, ITCs have been regarded as a promising anti-cancer therapeutic agent without major toxicity concerns. However, their clinical application has been hindered by several factors including their low aqueous solubility, low bioavailability, instability as well as their hormetic effect. Moreover, the typical dietary uptake of ITCs consumed for promotion of good health may be far from their bioactive (or cytotoxic) dose necessary for cancer prevention and/or treatment. Nanotechnology is one of best options to attain enhanced efficacy and minimize hormetic effect for ITCs. Nanoformulation of ITCs leads to enhance stability of ITCs in plasma and emphasize on their chemopreventive effects. This review provides a summary of the potential bioactivities of ITCs, their mechanisms of action for the prevention and treatment of cancer, as well as the recent research progress in their nanodelivery strategies to enhance solubility, bioavailability, and anti-cancer efficacy.

Dieckol alleviates dextran sulfate sodium-induced colitis via inhibition of inflammatory pathway and activation of Nrf2/HO-1 signaling pathway

Ulcerative colitis (UC) is the major type of inflammatory ailment with elevated prevalence worldwide. Dieckol (DEK) is a phlorotannin that is extensively found in marine algae and has been found to have different pharmacological properties. Nevertheless, the impact of DEK in UC has not been investigated earlier. Therefore, we appraised DEK's function in dextran sulfate sodium (DSS)-induced UC in the mouse. An overall of 30 mice was randomized into 5 equal groups. Control mice treated with a standard diet (group I), colitis mice challenged with 3% of DSS through drinking water for 7 consecutive days (group II), DEK was supplemented via oral gavage from day 1 to 10 at the dosages of 5, 10, and 15 mg/kg b.wt, respectively. All animals were sacrificed on the 11th day. The body weight (bwt), colon length, disease activity index, malondialdehyde (MDA), myeloperoxidase (MPO), and histological features were observed using suitable techniques, and COX-2 expression was investigated by immunohistochemistry. Moreover, TNF-α, IL-1β, p65, IκBα, HO-1, and Nrf2 expressions were measured using ELISA and RT-PCR techniques, respectively. DEK treatment to the colitis mice considerably lessened, DSS-challenged alterations in body weight, DAI, colonic length shortening and histological changes. DEK exhibited potent antioxidant effects due to the reduced MDA and MPO, and Nrf2 expression markers while the HO-1 marker was augmented. Additionally, DEK also suppressed the expression s of TNF-α, IL-1β, and the p-p65, p-IκBα, and p65 and augmented the expression of IκBα, which eventually proved the anti-inflammatory potential of DEK against the DSS-challenge. Based on these results, DEK has been found effective in mitigating colitis, conceivably alleviating colon inflammation through the NF-κB inhibition and triggering of Nrf2/HO-1 signaling cascade.

Methylglyoxal-Dependent Glycative Stress Is Prevented by the Natural Antioxidant Oleuropein in Human Dental Pulp Stem Cells through Nrf2/Glo1 Pathway

Methylglyoxal (MG) is a potent precursor of glycative stress (abnormal accumulation of advanced glycation end products, AGEs), a relevant condition underpinning the etiology of several diseases, including those of the oral cave. At present, synthetic agents able to trap MG are known; however, they have never been approved for clinical use because of their severe side effects. Hence, the search of bioactive natural scavengers remains a sector of strong research interest. Here, we investigated whether and how oleuropein (OP), the major bioactive component of olive leaf, was able to prevent MG-dependent glycative stress in human dental pulp stem cells (DPSCs). The cells were exposed to OP at 50 µM for 24 h prior to the administration of MG at 300 µM for additional 24 h. We found that OP prevented MG-induced glycative stress and DPSCs impairment by restoring the activity of Glyoxalase 1 (Glo1), the major detoxifying enzyme of MG, in a mechanism involving the redox-sensitive transcription factor Nrf2. Our results suggest that OP holds great promise for the development of preventive strategies for MG-derived AGEs-associated oral diseases and open new paths in research concerning additional studies on the protective potential of this secoiridoid.

Biological properties and development of hypoxia in a breast cancer 3D model generated by hanging drop technique

Hanging drop represents a simple approach designed for the generation of 3D models that have potential to be used for the study of solid tumors characteristics. The aim of the study was to develop and characterize the breast cancer 3D cellular models obtained through hanging drop technique using MDA-MB-231 cells. The biological characteristics such as: morphology, cellular viability, proliferation capacity and hypoxia, were monitored for a six-day time period. The morphological evaluation indicated that the 3D models presented the aspect of compact (seeding density of 2500 and 5000 cells/drop) and loose (seeding density of 8000 cells/drop) aggregates, with a decrease in diameter and an increase of their circularity. The cellular viability and proliferation capacity decreased in time and the level of lactate dehydrogenase (LDH) increased in a time-dependent manner, suggesting the presence of necrotic cells that were dispersed in the cellular aggregates. The occurrence of hypoxia process was suggested by the up-regulation of Hsp70 protein expression and increased level of nitric oxide (NO). Moreover, the up-regulation of HIF-1α and poli-ubiquitinated Nrf2 protein expressions and decreased level of reduced glutathione (GSH) indicated the presence of an acute hypoxic environment in MDA-MB-231 3D aggregates. In conclusion, the MDA-MB-231 3D models generated through hanging drop are compact and loose aggregates characterized by an acute hypoxic condition.

A review on herbal Nrf2 activators with preclinical evidence in cardiovascular diseases

Cardiovascular diseases (CVDs) are an ever-growing problem and are the most common cause of death worldwide. The uncontrolled production of reactive oxygen species (ROS) and the activation of ROS associated with various cell signaling pathways with oxidative cellular damage are the most common pathological conditions connected with CVDs including endothelial dysfunction, hypercontractility of vascular smooth muscle, cardiac hypertrophy and heart failure. The nuclear factor E2-related factor 2 (Nrf2) is a basic leucine zipper redox transcription factor, together with its negative regulator, kelch-like ECH-associated protein 1 (Keap1), which serves as a key regulator of cellular defense mechanisms to combat oxidative stress and associated diseases. Multiple lines of evidence described here support the cardiac protective property of Nrf2 in various experimental models of cardiac related disease conditions. In this review, we emphasized the molecular mechanisms of Nrf2 and described the detailed outline of current findings on the therapeutic possibilities of the Nrf2 activators specifically from herbal origin in various CVDs. Based on evidence from various preclinical experimental models, we have highlighted the activation of Nrf2 pathway as a budding therapeutic option for the prevention and treatment of CVDs, which needs further investigation and validation in the clinical settings.

Dose- and time-effects responses of Nonylphenol on oxidative stress in rat through the Keap1-Nrf2 signaling pathway

Nonylphenol (NP) is a representative environmental endocrine-disrupting compound that can induce oxidative stress in organisms. The Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway acts an important role in preventing oxidative stress. The aim of this study was to investigate the influence of oxidative stress caused by NP on Keap1-Nrf2 pathway in rats. Rats were treated with NP (30, 90, 270 mg/kg) for different exposure time (7, 14 and 28 days). The levels of reactive oxygen species (ROS) in serum and glutathione S-transferase (GST), UDP-Glucuronosyl Transferase (UGT) in liver were detected by ELISA kits. Western blot was used to detect Keap1, Nrf2 protein expression in liver and cerebral cortex. The results showed that 28 days of NP exposure significantly increased ROS levels in NPH group. And 14 days exposure to NP significantly enhanced the levels of GST and UGT, while 28 days of exposure showed a suppressive effect. In liver, Keap1 levels was upregulated at 7, 14 and 28 days of NP exposure, while nuclear Nrf2 levels decreased at 7 and 28 days but increased at 14 days. In cerebral cortex, Keap1 and Nrf2 expression increased at 14 days but decreased at 28 days. Besides, with the prolongation of NP exposure time, the GST and UGT levels in NPM and NPH groups were increased firstly and then decreased, while Keap1 and Nrf2 protein levels were constantly decreased in liver and cerebral cortex. In conclusion, the lower dose and shorter exposure time of NP activated the Keap1-Nrf2 pathway that may reduce the damage of oxidative stress, but when further exposed to NP at higher dose and time, the pathway could be inhibited.

Icariin enhances youth-like features by attenuating the declined gut microbiota in the aged mice

We previously reported the neuroprotective effects of icariin in rat cortical neurons. Here, we present a study on icariin's anti-aging effect in 24-month aged mice by treating them with a single daily dose of 100 mg/kg of icariin for 15 consecutive days. Icariin treatment improved motor coordination and learning skills while lowered oxidative stress biomarkers in the serum, brain, kidney, and liver of the aged mice. In addition, icariin improved the intestinal integrity of the aged mice by upregulating tight junction adhesion molecules and the Paneth and goblet cells, along with the reduction of iNOS and pro-inflammatory cytokines (IL-1β, TNF-α, IL-2 and IL-6, and IL-12). Icariin treatments also significantly upregulated aging-related signaling molecules, Sirt 1, 3 & 6, Pot1α, BUB1b, FOXO1, Ep300, ANXA3, Calb1, SNAP25, and BDNF in old mice. Through gut microbiota (GM) analysis, we observed icariin-associated improvements in GM composition of aged mice by reinstating bacteria found in the young mice, while suppressing some bacteria found in the untreated old mice. To clarify whether icariin's anti-aging effect is rooted in the GM, we performed fecal microbiota transfer (FMT) from icariin-treated old mice to the old mice. FMT-recipients exhibited similar improvements in the rotarod score and age-related biomarkers as observed in the icariin-treated old mice. Equal or better improvement on the youth-like features was noticed when aged mice were FMT with feces from young mice. Our study shows that both direct treatments with icariin and fecal transplant from the icariin-treated aged mice produce similar anti-aging phenotypes in the aged mice. We prove that GM plays a pivotal role in the healing abilities of icariin. Icariin has the potentials to be developed as a medicine for the wellness of the aged adults.

CXCR4 promotes B cell viability by the cooperation of nuclear factor (erythroid-derived 2)-like 2 and hypoxia-inducible factor-1α under hypoxic conditions

B cells that interact with T cells play a role in regulating the defense function by producing antibodies and inflammatory cytokines. C-X-C chemokine receptor type 4 (CXCR4) is a specific receptor for stromal cell-derived factor 1 (SDF-1) that controls various B cell functions. Here, we investigated whether CXCR4 regulates B cell viability by inducing hypoxia-inducible factor (HIF)-1α and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) under a hypoxic condition in WiL2-NS human B cells. Nrf2 and CXCR4 expressions increased significantly when WiL2-NS cells were incubated under a hypoxic condition. Interfering with CXCR4 expression using CXCR4-siRNA inhibited cell viability. CXCR4 expression also decreased after treatment with a HIF inhibitor under the hypoxic condition, leading to inhibited cell viability. Increased reactive oxygen species (ROS) levels and the expression of HIF-1α and Nrf2 decreased under the hypoxic condition following incubation with N-acetylcysteine, a ROS scavenger, which was associated with a decrease in CXCR4 expression. CXCR4 expression was augmented by overexpressing Nrf2 after transfecting the pcDNA3.1-Nrf2 plasmid. CXCR4 expression decreased and HIF-1α accumulation decreased when Nrf2 was inhibited by doxycycline in tet-shNrf2-expressed stable cells. Nrf2 or HIF-1α bound from -718 to -561 of the CXCR4 gene promoter as judged by a chromatin immunoprecipitation assay. Taken together, these data show that B cell viability under a hypoxic condition could be regulated by CXCR4 expression through binding of HIF-1α and Nrf2 to the CXCR4 gene promoter cooperatively. These results suggest that CXCR4 could be an additional therapeutic target to control B cells with roles at disease sites under hypoxic conditions.

Roflumilast protects from cisplatin-induced testicular toxicity in male rats and enhances its cytotoxicity in prostate cancer cell line. Role of NF-κB-p65, cAMP/PKA and Nrf2/HO-1, NQO1 signaling

Cisplatin (CIS)-induced testicular injury is a major obstacle in its application as antineoplastic agent. In this study, we investigated the protective effect and mechanism of roflumilast (ROF), a PDE4 inhibitor, against CIS-induced testicular toxicity in rats. Besides, the cytotoxic effect of CIS, with and without ROF, was evaluated on PC3 cell line. ROF reversed CIS-induced abnormalities in sperm characteristics, normalized serum testosterone level, and ameliorated CIS-induced alterations in testicular and epidydimal weights and restored normal testicular structure. Moreover, ROF increased intracellular cAMP level, PKA and HO-1 activities and Nrf2, NQO-1 and HO-1 gene expression, improved testicular oxidative stress parameters (TBARS, NO, GSH levels, and CAT activity) and inflammatory mediators (IL-1β and TNF-α, and NF-κβ p65gene expression) and reduced the proapoptotic proteins, caspase-3, Bax and increased Bcl-2. Lastly, in vitro analyses showed that ROF augmented the anticancer efficacy of CIS and enhanced the increase in gene expression of Nrf2, HO-1, and NQO-1 and the inhibition of gene expression of NF-κβ p65 induced by CIS and enhanced its apoptotic effect in PC3 cells. Conclusively, PDE4 inhibition with induction of Nrf2/HO-1, NQO-1 is a potential therapeutic approach to protect male reproductive system from the detrimental effects with augmenting, the antineoplastic effect of CIS.

Modification of the effects of aflatoxin B1 on the glutathione system and its regulatory genes by zeolite

The purpose of the present study was to use oxidative stress markers for investigating the effect of zeolite (315 mg/kg of complete feed) in the case of aflatoxin B1 contamination (92 μg/kg complete feed). In a 21-day feeding trial with broiler chickens, oxidative stress parameters such as conjugated dienes, conjugated trienes, malondialdehyde, reduced glutathione content and glutathione peroxidase activity were not changed significantly by supplementation with this mycotoxin absorbent. The relative gene expression of transcription factors KEAP1 and NRF2 was not modified by the absorbent either. Still, the expression of GSS, GSR and GPX4 genes increased significantly due to the aluminosilicate supplementation. The results suggest that zeolite reduced lipid peroxidation in the blood plasma but not in the red blood cell haemolysate or the kidney. The relative expression of the genes encoding the glutathione redox system also changed as a result of zeolite supplementation, but these changes were not found at the protein level.

Lycium barbarum polysaccharides inhibit ischemia/reperfusion-induced myocardial injury via the Nrf2 antioxidant pathway

Oxidative stress is considered to be one of main pathophysiological mechanisms in myocardial ischemia/reperfusion (I/R) injury. Lycium barbarum polysaccharides (LBP), the main ingredient of Lycium barbarum, have potential antioxidant activity. We aimed to investigate the effects of LBP on myocardial I/R injury and explore the underlying mechanisms. Myocardial I/R group was treated with or without LBP to evaluate oxidative stress markers and the role of Nrf2 signal pathway. Our results showed that I/R increased infarct size and the activities of creatine kinase (CK) and lactate dehydrogenase (LDH) when compared with control group. Meanwhile, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were enhanced and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) were decreased. These changes were associated with a significant increase in myocardial apoptosis, ultimately leading to cardiac dysfunction. LBP reduced infarct size (38.4 ± 2 % versus 19.4 ± 1.8 %, p < 0.05), CK and LDH activities and myocardial apoptotic index. Meanwhile, LBP suppressed the production of ROS and restored redox status. Additionally, LBP increased protein level of nuclear Nrf2 in vivo (2.1 ± 0.3 versus 3.8 ± 0.4, p < 0.05) and in vitro (1.9 ± 0.2 versus 3.8 ± 0.1, p < 0.05) and subsequently upregulated heme oxygenase 1 and NADPH dehydrogenase quinone 1 compared to I/R group. Interestingly, Nrf2 siRNA abolished the protective effects of LBP. LBP suppressed oxidative stress damage and attenuated cardiac dysfunction induced by I/R via activation of the Nrf2 antioxidant signal pathway.

The Nrf2 pathway in psychiatric disorders: pathophysiological role and potential targeting

Introduction: All psychiatric disorders exhibit excitotoxicity, mitochondrial dysfunction, inflammation, oxidative stress, and neural damage as their common characteristic. The endogenous nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway is implicated in the defense mechanism against oxidative stress and has a significant role in psychiatric disorders.Areas covered: We explore the role of Nrf2 pathway and its modulators in psychiatric disorders. The literature was searched utilizing various databases such as Embase, Medline, Web of Science, Pub-Med, and Google Scholar from 2010 to 2020. The search included research articles, clinical reports, systematic reviews, and meta-analyses.Expert opinion: Environmental factors and genetic predisposition can be a trigger for the development of psychiatric disorders. Nrf2 downregulates certain inflammatory pathways and upregulates various antioxidant enzymes to maintain a balance. However, its intricate balance with NF-Kβ (Nuclear factor kappa light chain enhancer of activated B cells) and its crosstalk with the transcription factor Nrf2 is critical in severe oxidative stress. Several Nrf2 modulators are now in clinical trials and can help reduce oxidative stress and neuroinflammation. There are immense potential opportunities for these modulators to become a novel therapeutic option.