Nrf2 for protection against oxidant generation and mitochondrial damage in cardiac injury

Nrf2: A Main Responsive Element of the Toxicity Effect Caused by Trichothecene (T-2) Mycotoxin

T-2 toxin, the most toxic type A trichothecene mycotoxin, is produced by Fusarium, and is widely found in contaminated feed and stored grains. T-2 toxin is physicochemically stable and is challenging to eradicate from contaminated feed and cereal, resulting in food contamination that is inescapable and poses a major hazard to both human and animal health, according to the World Health Organization. Oxidative stress is the upstream cause of all pathogenic variables, and is the primary mechanism through which T-2 toxin causes poisoning. Nuclear factor E2-related factor 2 (Nrf2) also plays a crucial part in oxidative stress, iron metabolism and mitochondrial homeostasis. The major ideas and emerging trends in future study are comprehensively discussed in this review, along with research progress and the molecular mechanism of Nrf2's involvement in the toxicity impact brought on by T-2 toxin. This paper could provide a theoretical foundation for elucidating how Nrf2 reduces oxidative damage caused by T-2 toxin, and a theoretical reference for exploring target drugs to alleviate T-2 toxin toxicity with Nrf2 molecules.

Mitigation of Cardiovascular Disease and Toxicity through NRF2 Signalling

Cardiovascular toxicity and diseases are phenomena that have a vastly detrimental impact on morbidity and mortality. The pathophysiology driving the development of these conditions is multifactorial but commonly includes the perturbance of reactive oxygen species (ROS) signalling, iron homeostasis and mitochondrial bioenergetics. The transcription factor nuclear factor erythroid 2 (NFE2)-related factor 2 (NRF2), a master regulator of cytoprotective responses, drives the expression of genes that provide resistance to oxidative, electrophilic and xenobiotic stresses. Recent research has suggested that stimulation of the NRF2 signalling pathway can alleviate cardiotoxicity and hallmarks of cardiovascular disease progression. However, dysregulation of NRF2 dynamic responses can be severely impacted by ageing processes and off-target toxicity from clinical medicines including anthracycline chemotherapeutics, rendering cells of the cardiovascular system susceptible to toxicity and subsequent tissue dysfunction. This review addresses the current understanding of NRF2 mechanisms under homeostatic and cardiovascular pathophysiological conditions within the context of wider implications for this diverse transcription factor.

Resveratrol Protects BEAS-2B Cells against Erastin-Induced Ferroptosis through the Nrf2/Keap1 Pathway

Ferroptosis is a newly discovered type of cell death that is different from other types of cell death morphologically and biologically. It is considered to play an important role in many pulmonary diseases. Currently, the regulatory roles of antioxidation in lung epithelial ferroptosis have not been fully explored. In this study, we show that resveratrol protected erastin-induced ferroptosis in BEAS-2B cells. Erastin led to increased reactive oxygen species production and iron deposition in BEAS-2B cells, which could be rescued by resveratrol. Furthermore, we observed that resveratrol led to modulating ferroptosis-associated gene glutathione peroxidase 4 expression and regulating glutathione in BEAS-2B cells. Resveratrol exerted an antioxidant property in erastin-induced ferroptosis of BEAS-2B cells by activating the nuclear factor-erythroid 2-related factor 2/Kelch-like ECH-associated protein signaling pathway. Finally, these findings demonstrate that resveratrol protects BEAS-2B from erastin-induced ferroptosis.

Natural products for kidney disease treatment: Focus on targeting mitochondrial dysfunction

The patients with kidney diseases are increasing rapidly all over the world. With the rich abundance of mitochondria, kidney is an organ with a high consumption of energy. Hence, renal failure is highly correlated with the breakup of mitochondrial homeostasis. However, the potential drugs targeting mitochondrial dysfunction are still in mystery. The natural products have the superiorities to explore the potential drugs regulating energy metabolism. However, their roles in targeting mitochondrial dysfunction in kidney diseases have not been extensively reviewed. Herein, we reviewed a series of natural products targeting mitochondrial oxidative stress, mitochondrial biogenesis, mitophagy, and mitochondrial dynamics. We found lots of them with great medicinal values in kidney disease. Our review provides a wide prospect for seeking the effective drugs targeting kidney diseases.

Mitofusin-2 mediates cannabidiol-induced neuroprotection against cerebral ischemia in rats

Cannabidiol (CBD) reportedly exerts protective effects against many psychiatric disorders and neurodegenerative diseases, but the mechanisms are poorly understood. In this study, we explored the molecular mechanism of CBD against cerebral ischemia. HT-22 cells or primary cortical neurons were subjected to oxygen-glucose deprivation insult followed by reoxygenation (OGD/R). In both HT-22 cells and primary cortical neurons, CBD pretreatment (0.1, 0.3, 1 μM) dose-dependently attenuated OGD/R-induced cell death and mitochondrial dysfunction, ameliorated OGD/R-induced endoplasmic reticulum (ER) stress, and increased the mitofusin-2 (MFN2) protein level in HT-22 cells and primary cortical neurons. Knockdown of MFN2 abolished the protective effects of CBD. CBD pretreatment also suppressed OGD/R-induced binding of Parkin to MFN2 and subsequent ubiquitination of MFN2. Overexpression of Parkin blocked the effects of CBD in reducing MFN2 ubiquitination and reduced cell viability, whereas overexpressing MFN2 abolished Parkin's detrimental effects. In vivo experiments were conducted on male rats subjected to middle cerebral artery occlusion (MCAO) insult, and administration of CBD (2.5, 5 mg · kg-1, i.p.) dose-dependently reduced the infarct volume and ER stress in the brains. Moreover, the level of MFN2 within the ischemic penumbra of rats was increased by CBD treatment, while the binding of Parkin to MFN2 and the ubiquitination of MFN2 was decreased. Finally, short hairpin RNA against MFN2 reversed CBD's protective effects. Together, these results demonstrate that CBD protects brain neurons against cerebral ischemia by reducing MFN2 degradation via disrupting Parkin's binding to MFN2, indicating that MFN2 is a potential target for the treatment of cerebral ischemia.

Depleted uranium causes renal mitochondrial dysfunction through the ETHE1/Nrf2 pathway

The kidney is the main organ affected by acute depleted uranium (DU) toxicity. The mechanism of nephrotoxicity induced by DU is complex and needs to be further explored. This study aimed to elucidate the function of mitochondrial dysfunction in nephrotoxicity generated by DU and confirm the latent mechanism. We verified that DU (2.5-10 mg/kg) caused mitochondrial dysfunction in male rat kidneys and decreased ATP content and the mitochondrial membrane potential. In addition, melatonin (20 mg/kg), as an antioxidant, alleviated DU-induced oxidative stress and mitochondrial dysfunction in male rats, further reducing kidney damage caused by DU. These results indicate that mitochondrial dysfunction plays a vital role in DU nephrotoxicity. When ethylmalonic encephalopathy 1 (ETHE1) was knocked down, DU-induced oxidative stress and mitochondrial dysfunction were increased, and renal injury was aggravated. When exogenous ETHE1 protein was applied to renal cells, the opposite changes were observed. We also found that ETHE1 knockdown increased the expression of NF-E2-related factor 2 (Nrf2), a vital oxidative stress regulator, and its downstream molecules heme oxygenase-1 (HO-1) and NADPH quinone oxidoreductase 1 (NQO1). Nrf2 knockout also aggravated DU-induced oxidative stress, mitochondrial dysfunction, and kidney damage. In conclusion, DU causes oxidative stress and antioxidant defense imbalance in renal cells through the ETHE1/Nrf2 pathway, further causing mitochondrial dysfunction and ultimately leading to nephrotoxicity.

Hyperkalemic or Low Potassium Cardioplegia Protects against Reduction of Energy Metabolism by Oxidative Stress

Open-heart surgery is often an unavoidable option for the treatment of cardiovascular disease and prevention of cardiomyopathy. Cardiopulmonary bypass surgery requires manipulating cardiac contractile function via the perfusion of a cardioplegic solution. Procedure-associated ischemia and reperfusion (I/R) injury, a major source of oxidative stress, affects postoperative cardiac performance and long-term outcomes. Using large-scale liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics, we addressed whether cardioplegic solutions affect the baseline cellular metabolism and prevent metabolic reprogramming by oxidative stress. AC16 cardiomyocytes in culture were treated with commonly used cardioplegic solutions, High K+ (HK), Low K+ (LK), Del Nido (DN), histidine-tryptophan-ketoglutarate (HTK), or Celsior (CS). The overall metabolic profile shown by the principal component analysis (PCA) and heatmap revealed that HK or LK had a minimal impact on the baseline 78 metabolites, whereas HTK or CS significantly repressed the levels of multiple amino acids and sugars. H2O2-induced sublethal mild oxidative stress causes decreases in NAD, nicotinamide, or acetylcarnitine, but increases in glucose derivatives, including glucose 6-P, glucose 1-P, fructose, mannose, and mannose 6-P. Additional increases include metabolites of the pentose phosphate pathway, D-ribose-5-P, L-arabitol, adonitol, and xylitol. Pretreatment with HK or LK cardioplegic solution prevented most metabolic changes and increases of reactive oxygen species (ROS) elicited by H2O2. Our data indicate that HK and LK cardioplegic solutions preserve baseline metabolism and protect against metabolic reprogramming by oxidative stress.

Association of mitochondrial homeostasis and dynamic balance with malignant biological behaviors of gastrointestinal cancer

Mitochondria determine the physiological status of most eukaryotes. Mitochondrial dynamics plays an important role in maintaining mitochondrial homeostasis, and the disorder in mitochondrial dynamics could affect cellular energy metabolism leading to tumorigenesis. In recent years, disrupted mitochondrial dynamics has been found to influence the biological behaviors of gastrointestinal cancer with the potential to be a novel target for its individualized therapy. This review systematically introduced the role of mitochondrial dynamics in maintaining mitochondrial homeostasis, and further elaborated the effects of disrupted mitochondrial dynamics on the cellular biological behaviors of gastrointestinal cancer as well as its association with cancer progression. We aim to provide clues for elucidating the etiology and pathogenesis of gastrointestinal cancer from the perspective of mitochondrial homeostasis and disorder.

Fresh Medium or L-Cystine as an Effective Nrf2 Inducer for Cytoprotection in Cell Culture

The Nrf2 gene encodes a transcription factor best known for regulating the expression of antioxidant and detoxification genes. A long list of small molecules has been reported to induce Nrf2 protein via Keap1 oxidation or alkylation. Many of these Nrf2 inducers exhibit off-target or toxic effects due to their nature as electrophiles. In searching for non-toxic Nrf2 inducers, we found that a culture medium change to fresh DMEM is capable of inducing Nrf2 protein in HeLa, HEK293, AC16 and MCF7 cells. Testing the components of DMEM led to the discovery of L-Cystine as an effective Nrf2 inducer. L-Cystine induces a dose-dependent increase of Nrf2 protein, from 0.1 to 1.6 mM. RNA-seq analyses and RT-PCR revealed an induction of multiple Nrf2 downstream genes, including NQO1, HMOX1, GCLC, GCLM, SRXN1, TXNRD1, AKR1C and OSGIN1 by 0.8 mM L-Cystine. The induction of Nrf2 protein was dependent on L-Cystine entering cells via the cystine/glutamate antiporter and the presence of Keap1. The half-life of Nrf2 protein increased from 19.4 min to 30.9 min with 0.8 mM L-Cystine treatment. L-Cystine was capable of eliciting cytoprotection by reducing ROS generation and protecting against oxidant- or doxorubicin-induced apoptosis. As an amino acid derivative, L-Cystine is considered a non-toxic Nrf2 inducer that exhibits the potential for protection against oxidative stress and tissue injury.

Swietenine Alleviates Vascular Remodelling by Enhancing Mitophagy of Pulmonary Arterial Smooth Muscle Cells in Experimental Pulmonary Hypertension

BACKGROUND

Vascular remodelling during pulmonary hypertension (PH) is characterized by the phenotypic transformation of pulmonary arterial smooth muscle cells (PASMCs). Swietenine (Swi), extracted from the seeds of traditional medicine Swietenia mahagoni, has been used to treat cardiac remodelling, but the effect of Swi on PH is unknown. This study aims to evaluate the effect of Swi on hypoxia-induced phenotypic transformation of PASMCs in experimental PH.

METHODS

In our research, C57BL/6 mice were treated with SU5416 and exposed to hypoxia for 4 weeks to establish HySu-PH model. Mice in the Swi treatment group were subjected to HySu with daily administration of Swi. Hemodynamic parameters, echocardiography, and degree of vascular muscularization were measured to evaluate the PH model. Proliferation of PASMC was assessed by Ki67 and EdU assay. Cell migration was detected by wound-healing assay. Mitophagy levels were evaluated by mito-tracker and lyso-tracker, autophagic flux, and protein expression of Pink1 and Lc3Ⅱ. The molecular docking was used to validate the interaction of Swi with Nrf2. Immunofluorescence and immunohistochemical staining was applied to determine the subcellular localization of Nrf2.

RESULTS

The results showed that Swi attenuated hypoxia-induced increase of right ventricle systolic pressure, Fulton index, and vascular remodelling and decreased PASMC proliferation, migration, and enhanced mitophagy. Furthermore, the interaction of Swi with Nrf2 promoted the translocation of Nrf2 into the nucleus, resulting in the induction of Pink1.

CONCLUSIONS

This study demonstrates that Swi prevents vascular remodelling in experimental PH through inhibition of phenotypic transformation and hyperproliferation of PASMCs caused by reversing hypoxia-induced inhibition of mitophagy.

The Role of Nrf2 in Relieving Cerebral Ischemia-Reperfusion Injury

Ischemic stroke includes two related pathological damage processes: brain injury caused by primary ischemia and secondary ischemia reperfusion (I/R) injury. I/R injury has become a worldwide health problem. Unfortunately, there is still a lack of satisfactory drugs for ameliorating cerebral I/R damage. Nrf2 is a vital endogenous antioxidant protein, which combines with Keap1 to maintain a dormant state under physiological conditions. When pathological changes such as I/R occurs, Nrf2 dissociates from Keap1 and activates the expression of downstream antioxidant proteins to exert a protective effect. Recent research have shown that the activated Nrf2 not only effectively inhibits oxidative stress, but also performs the ability to repair the function of compromised mitochondria, alleviate endoplasmic reticulum stress, eliminate inflammatory response, reduce blood-brain barrier permeability, inhibit neuronal apoptosis, enhance the neural network remolding, thereby exerting significant protective effects in alleviating the injuries caused by cell oxygen-glucose deprivation, or animal cerebral I/R. However, no definite clinical application report demonstrated the efficacy of Nrf2 activators in the treatment of cerebral I/R. Therefore, further efforts are needed to elaborate the role of Nrf2 activators in the treatment of cerebral I/R. Here, we reviewed the possible mechanisms underlying its potential pharmacological benefits in alleviating cerebral I/R injury, so as to provide a theoretical basis for studying its mechanism and developing Nrf2 activators.

Nrf2 attenuates methamphetamine-induced myocardial injury by regulating oxidative stress and apoptosis in mice

OBJECTIVES

Methamphetamine (MA) abuse is a serious social problem worldwide. Cardiovascular complications were the second leading cause of death among MA abusers. We aimed to clarify the effects of MA on myocardial injury, oxidative stress, and apoptosis in myocardial cells and to explore the potential mechanism of nuclear factor-erythroid factor 2-related factor 2 (Nrf2) in MA-induced oxidative stress and apoptosis.

METHODS

An acute cardiac toxicity model of MA was established by intraperitoneal injection of MA (2 mg/kg) for 5 days. Nrf2 activation (by sulforaphane (SFN) 1 h before MA injection) and Nrf2 gene knockout were performed to explore the regulatory effects of Nrf2 on cardiac toxicity.

RESULTS

The protein expressions of Nrf2 (p < .001) and heme oxygenase-1 (HO-1) were increased (p < .01), suggesting that MA activated the Nrf2/HO-1 pathway. In the MA group, cardiac injury score (p < .001) and cardiac troponin I (cTnI) protein expression increased (p < .01). Malondialdehyde (MDA) content increased (p < .001), superoxide dismutase (SOD) activity decreased (p < .05). Protein expressions of Caspase-3 (p < .001) and Bax (p < .001) increased, and Bcl-2 decreased (p < .001) as well. These changes were reversed by activation of Nrf2 but became more pronounced after Nrf2 knockout, suggested that the activation and knockout of Nrf2 attenuated and aggravated MA-induced myocardial injury, oxidative stress and apoptosis in myocardial cells, respectively.

CONCLUSIONS

MA administration induced myocardial injury, oxidative stress, and apoptosis in mice. Nrf2 attenuated MA-induced myocardial injury by regulating oxidative stress and apoptosis, thus playing a protective role.

Zhen Wu decoction represses renal fibrosis by invigorating tubular NRF2 and TFAM to fuel mitochondrial bioenergetics

BACKGROUND

Zhen Wu Decoction (ZWD) is a prescription from the classical text "Treatise on Exogenous Febrile Disease" and has been extensively used to control kidney diseases since the time of the Eastern Han Dynasty.

HYPOTHESIS

We hypothesized that ZWD limits tubular fibrogenesis by reinvigorating tubular bio-energetic capacity.

STUDY DESIGN / METHODS

A mouse model of chronic kidney disease (CKD) was established using unilateral ureteral obstruction (UUO). Three concentrations of ZWD, namely 25.2 g/kg (high dosage), 12.6 g/kg (middle dosage), and 6.3 g/kg (low dosage), were included to study the dose-effect relationship. Real-time qPCR was used to observe gene transcription in blood samples from patients with CKD. Different siRNAs were designed to study the role of mitochondrial transcription factor A (TFAM) and nuclear factor (erythroid-derived 2)-related factor 2 (NRF2) in transforming growth factor (TGF)-β1 induced fibrogenesis and mitochondrial damage.

RESULTS

We showed that ZWD efficiently attenuates renal function impairment and reduces renal interstitial fibrosis. TFAM and NRF2 were repressed, and the stimulator of interferon genes (STING) was activated in CKD patient blood sample. We further confirmed that ZWD activated TFAM depended on NRF2 as an important negative regulator of STING in mouse kidneys. Treatment with ZWD significantly reduced oxidative stress and inflammation by regulating the levels of oxidative phosphorylation (OXPHOS) and pro-inflammatory factors, such as interleukin-6, interleukin-1β, tumor necrosis factor receptor 1, and mitochondrial respiratory chain subunits. NRF2 inhibitors can weaken the ability of ZWD to increase TFAM expression and heal injured mitochondria, playing a similar role to that of STING inhibitors. Our study showed that ZWD elevates the expression of TFAM and mitochondrial respiratory chain subunits by promoting NRF2 activation, after suppressing mitochondrial membrane damage and cristae breakdown and restricting mitochondrial DNA (mtDNA) leakage into the cytoplasm to reduce STING activation.

CONCLUSION

ZWD maintains mitochondrial integrity and improves OXPHOS which represents an innovative insight into "strengthening Yang-Qi" theory. ZWD limits tubular fibrogenesis by reinvigorating tubular bioenergetic capacity.

Garlic (Allium sativum L.) in diabetes and its complications: Recent advances in mechanisms of action

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia and impaired islet secretion that places a heavy burden on the global health care system due to its high incidence rate, long disease course and many complications. Fortunately, garlic (Allium sativum L.), a well-known medicinal plant and functional food without the toxicity and side effects of conventional drugs, has shown positive effects in the treatment of diabetes and its complications. With interdisciplinary development and in-depth exploration, we offer a clear and comprehensive summary of the research from the past ten years, focusing on the mechanisms and development processes of garlic in the treatment of diabetes and its complications, aiming to provide a new perspective for the treatment of diabetes and promote the efficient development of this field.

ROS: Basic Concepts, Sources, Cellular Signaling, and its Implications in Aging Pathways

Reactive oxygen species (ROS) are bioproducts of cellular metabolism. There is a range of molecules with oxidizing properties known as ROS. Despite those molecules being implied negatively in aging and numerous diseases, their key role in cellular signaling is evident. ROS control several biological processes such as inflammation, proliferation, and cell death. The redox signaling underlying these cellular events is one characteristic of the new generation of scientists aimed at defining the role of ROS in the cellular environment. The control of redox potential, which includes the balance of the sources of ROS and the antioxidant system, implies an important target for understanding the cells' fate derived from redox signaling. In this review, we summarized the chemical, the redox balance, the signaling, and the implications of ROS in biological aging.

Oleuropein attenuates testicular ischemia-reperfusion by inhibiting apoptosis and inflammation

BACKGROUND

Ischemia-reperfusion injury (IRI) is the key reason of injury after testicular torsion and may eventually lead to male infertility. Oleuropein, a natural antioxidant isolated from Olea europaea, has shown beneficial effects in different models of ischemia. We evaluated the effects of oleuropein on testicular IRI and explored the underlying protective mechanisms.

METHODS

A mouse testicular torsion/detorsion (T/D) model and an oxygen-glucose deprivation/reperfusion (OGD/R) germ cell model were established and treated with oleuropein. H&E staining was used to evaluate testicular pathological changes. Apoptosis and apoptosis-associated protein levels in testis tissues were assessed by TUNEL staining, immunohistochemical staining and western blot. Apoptosis levels and apoptosis-associated protein levels in GC-1 were evaluated by flow cytometry, immunofluorescence and western blot. Oxidative stress levels were assessed by malondialdehyde (MDA) and superoxide dismutase (SOD) kits. Cell viability and inflammatory protein levels were evaluated by CCK-8 assay coupled with qRT-PCR.

RESULTS

Relative to the control group, SOD activity was markedly suppressed, while MDA, Bax, Caspase-3, TNF-α as well as IL-1β levels were significantly increased in the T/D model and OGD/R model. However, all of the aforementioned alterations were relieved by oleuropein treatment.

CONCLUSION

Our findings indicate that oleuropein may be a promising treatment option to attenuate testicular IRI via its anti-oxidant, anti-inflammatory as well as anti-apoptotic properties.

Combination of Metformin and Sorafenib Induces Ferroptosis of Hepatocellular Carcinoma Through p62-Keap1-Nrf2 Pathway

Hepatocellular carcinoma (HCC) is one of the most lethal cancers in the world. Sorafenib is the first small-molecule multi-kinase inhibitors approved by FDA for treatment of advanced HCC. Metformin has been demonstrated to have benefit for preventing cancer progression. In human recurrent HCCs, NF-E2-related factor 2 (Nrf2) was overexpressed and associated with poor survival. Nrf2 related signaling pathway plays central role to mediate cellular resistance to sorafenib through protecting HCC cells from ferroptosis. The effect of Combination treatment for HCC cells and the intrinsic mechanism have not been reported. In this study, metformin augmented the anti-tumor effect of sorafenib for HCC through ferroptosis induction by inhibiting Nrf2 related pathway. Based on the results of Nrf2 knockdown and p62 knockdown study, the combination of sorafenib and metformin suppressed proliferation of HCC cells through p62-Keap1-Nrf2/HO1 signaling way. Size of xenografts treated with the combination of sorafenib and metformin was smaller than other groups in vivo. Moreover, the combination treatment greatly induced ferroptosis in HCC cells through inhibiting Nrf2 expression. Based on our findings, the combination treatment suppressed proliferation of HCC cells through ferroptosis induction, by p62-Keap1-Nrf2/HO1 signaling way.

Neuroprotective Effects of a New Derivative of Chlojaponilactone B against Oxidative Damaged Induced by Hydrogen Peroxide in PC12 Cells

A new sesquiterpenoid (1) was obtained by hydrogenating Chlojaponilactone B. The structure of 1 was elucidated according to a combination of NMR, HRESIMS, and NOE diffraction data. The treatment of H₂O₂ in a PC12 cell model was used to evaluate the antioxidant activity of 1. An MMT assay showed that 1 had no cytotoxicity to the PC12 cell and rescued cell viability from the oxidative damage caused by H₂O₂. The treatment of 1 stabilized the mitochondria membrane potential (MMP), which decreased the intracellular ROS level and reduced cell apoptosis in the oxidative stress model. The activities of antioxidant enzyme superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the content of intracellular glutathione (GSH) were significantly enhanced after the treatment of 1. In addition, the results of qRT-PCR showed that 1 treatment minimized the cell injury by H₂O₂ via the up-regulation of the expression of nuclear factor erythroid 2 (Nrf2) and its downstream enzymes Heme oxygenase 1 (HO-1), glutamate cysteine ligase-modifier subunit (GCLm), and NAD(P)H quinone dehydrogenase 1 (Nqo1). Based on the antioxidant activity of 1, we speculated its potential as a therapeutic agent for some diseases induced by oxidative damage.

Quercetin Protects against MPP+/MPTP-Induced Dopaminergic Neuron Death in Parkinson's Disease by Inhibiting Ferroptosis

Ferroptosis, a novel form of regulated cell death, is caused by accumulation of lipid peroxides and excessive iron deposition. This process has been linked to the death of dopaminergic neurons in substantia nigra compacta (SNc) of Parkinson's disease (PD) patients. Quercetin (QCT), a natural flavonoid, has multiple pharmacological activities. However, it has not been established whether QCT can protect against dopaminergic neuron death by inhibiting ferroptosis. In this study, we investigated the potential antiferroptotic effects of QCT in cellular models established using specific ferroptosis inducers (Erastin and RSL-3) and MPP+. The effects were also explored using MPTP-induced PD mouse models. The cell counting kit-8 (CCK-8) assay was performed to assess cell viability. Variations in mitochondrial morphology were evaluated by transmission electron microscopy (TEM) while the mitochondrial membrane potential, mass, and ROS were measured by fluorescent probes. Lipid peroxidation levels were assayed through measurement of lipid ROS, MDA, GSH, and SOD levels. The effects of QCT on MPTP-induced behavioral disorders were examined by rotarod and open field tests. In vitro and in vivo, QCT significantly inhibited ferroptosis by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) protein. Additionally, QCT ameliorated motor behavioral impairments and protected against the loss of dopaminergic neurons in MPTP-induced PD models. Interestingly, Nrf2 knockdown alleviated the protective effects of QCT against ferroptosis. In conclusion, these results demonstrate that ferroptosis is involved in MPP+/MPTP-induced PD, and QCT inhibits ferroptosis by activating the Nrf2 protein. Therefore, QCT is a potential agent for preventing the loss of dopaminergic neurons by targeting ferroptosis.

AMPK and NRF2: Interactive players in the same team for cellular homeostasis?

NRF2 (Nuclear factor E2 p45-related factor 2) is a stress responsive transcription factor lending cells resilience against oxidative, xenobiotic, and also nutrient or proteotoxic insults. AMPK (AMP-activated kinase), considered as prime regulator of cellular energy homeostasis, not only tunes metabolism to provide the cell at any time with sufficient ATP or building blocks, but also controls redox balance and inflammation. Due to observed overlapping cellular responses upon AMPK or NRF2 activation and common stressors impinging on both AMPK and NRF2 signaling, it is plausible to assume that AMPK and NRF2 signaling may interdepend and cooperate to readjust cellular homeostasis. After a short introduction of the two players this narrative review paints the current picture on how AMPK and NRF2 signaling might interact on the molecular level, and highlights their possible crosstalk in selected examples of pathophysiology or bioactivity of drugs and phytochemicals.

The Nrf2 antioxidant defense system in intervertebral disc degeneration: Molecular insights

Intervertebral disc degeneration (IDD) is a common degenerative musculoskeletal disorder and is recognized as a major contributor to discogenic lower back pain. However, the molecular mechanisms underlying IDD remain unclear, and therapeutic strategies for IDD are currently limited. Oxidative stress plays pivotal roles in the pathogenesis and progression of many age-related diseases in humans, including IDD. Nuclear factor E2-related factor 2 (Nrf2) is a master antioxidant transcription factor that protects cells against oxidative stress damage. Nrf2 is negatively modulated by Kelch-like ECH-associated protein 1 (Keap1) and exerts important effects on IDD progression. Accumulating evidence has revealed that Nrf2 can facilitate the transcription of downstream antioxidant genes in disc cells by binding to antioxidant response elements (AREs) in promoter regions, including heme oxygenase-1 (HO-1), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and NADPH quinone dehydrogenase 1 (NQO1). The Nrf2 antioxidant defense system regulates cell apoptosis, senescence, extracellular matrix (ECM) metabolism, the inflammatory response of the nucleus pulposus (NP), and calcification of the cartilaginous endplates (EP) in IDD. In this review, we aim to discuss the current knowledge on the roles of Nrf2 in IDD systematically.

Insights into the activity of a protein that regulates gene expression and protects cells against oxidative stress could yield novel treatments for lower back pain. Intervertebral disc degeneration (IDD) is a common cause of lower back pain, but the molecular mechanisms underlying IDD are unclear, meaning treatment options are limited. Oxidative stress is implicated in IDD, and scientists have begun exploring the role of nuclear factor E2-related factor 2 (Nrf2), a master regulator of the body’s antioxidant responses, in regulating IDD progression. In a review of recent research, Weishi Li at Peking University Third Hospital, Beijing, China, and co-workers point out that boosting the activity of Nrf2-related signaling pathways alleviates oxidative stress in intervertebral disc cells. The researchers suggest that therapies based on non-coding RNAs may prove valuable in activating Nrf2 in IDD patients.

Wedelolactone facilitates the early development of parthenogenetically activated porcine embryos by reducing oxidative stress and inhibiting autophagy

Wedelolactone (WDL) is a coumaryl ether compound extracted from the traditional Chinese medicinal plant, Eclipta prostrata L. It is a natural polyphenol that exhibits a variety of pharmacological activities, such as anti-inflammatory, anti-free radical, and antioxidant activities in the bone, brain, and ovary. However, its effect on embryonic development remains unknown. The present study explored the influence of WDL supplementation of porcine oocytes culture in vitro on embryonic development and the underlying mechanisms and its effect on the levels of Kelch-like ECH-associated protein 1/nuclear factor-erythroid 2-related factor 2/antioxidant response element (Keap1/Nrf2/ARE). The results showed that WDL (2.5 nM) significantly increased the blastocyst formation rate, mitochondrial activity, and proliferation ability while reducing the reactive oxygen species accumulation, apoptosis, and autophagy. These findings suggested that WDL can enhance the growth and development of early porcine embryos to alleviate oxidative stress and autophagy through regulating NRF2 and microtubule-associated protein 1 light chain 3 (MAP1LC3) gene expression levels.

PRDX6 alleviates lipopolysaccharide-induced inflammation and ferroptosis in periodontitis

OBJECTIVE

Periodontitis is a progressive and inflammatory oral disease and results in the damage of the supporting tissues of teeth. Peroxiredoxin 6 (PRDX6) is an antioxidant enzyme identified as a regulator in ferroptosis. This study aimed to investigate whether PRDX6 could protect human gingival fibroblasts (HGFs) from lipopolysaccharide (LPS)-induced inflammation and its mechanisms.

MATERIAL AND METHODS

Both inflamed and non-inflamed human gingival tissues were collected to assess the expression of PRDX6 and nuclear factor erythropoietin 2-related factor 2 (NRF2) by Immunohistochemistry and Western blotting. Furthermore, the molecular mechanisms of PRDX6 have been clarified in PRDX6 silenced cells. The inflammatory cytokines in HGFs were measured by RT-qPCR and ELISA. The lipid hydroperoxide (LOOH) was detected by C11-BODIPY.

RESULTS

The expression of PRDX6 and NRF2 were decreased in gingival tissues of severe periodontitis patients. The increased LPS-induced LOOH and inflammatory cytokines were found in PRDX6 knockdown HGFs. Besides, the inhibition of ferroptosis or PRDX6 phospholipase A2 activity (PLA2) alleviated LPS-induced inflammatory cytokines and LOOH. However, inhibiting NRF2 signalling upregulated those in HGFs.

CONCLUSIONS

Therefore, this study provided a new mechanistic insight that PRDX6, regulated by the NRF2 signalling, alleviates LPS-induced inflammation and ferroptosis in human gingival fibroblasts.

Multi-Target Effects of ß-Caryophyllene and Carnosic Acid at the Crossroads of Mitochondrial Dysfunction and Neurodegeneration: From Oxidative Stress to Microglia-Mediated Neuroinflammation

Inflammation and oxidative stress are interlinked and interdependent processes involved in many chronic diseases, including neurodegeneration, diabetes, cardiovascular diseases, and cancer. Therefore, targeting inflammatory pathways may represent a potential therapeutic strategy. Emerging evidence indicates that many phytochemicals extracted from edible plants have the potential to ameliorate the disease phenotypes. In this scenario, ß-caryophyllene (BCP), a bicyclic sesquiterpene, and carnosic acid (CA), an ortho-diphenolic diterpene, were demonstrated to exhibit anti-inflammatory, and antioxidant activities, as well as neuroprotective and mitoprotective effects in different in vitro and in vivo models. BCP essentially promotes its effects by acting as a selective agonist and allosteric modulator of cannabinoid type-2 receptor (CB2R). CA is a pro-electrophilic compound that, in response to oxidation, is converted to its electrophilic form. This can interact and activate the Keap1/Nrf2/ARE transcription pathway, triggering the synthesis of endogenous antioxidant “phase 2” enzymes. However, given the nature of its chemical structure, CA also exhibits direct antioxidant effects. BCP and CA can readily cross the BBB and accumulate in brain regions, giving rise to neuroprotective effects by preventing mitochondrial dysfunction and inhibiting activated microglia, substantially through the activation of pro-survival signalling pathways, including regulation of apoptosis and autophagy, and molecular mechanisms related to mitochondrial quality control. Findings from different in vitro/in vivo experimental models of Parkinson’s disease and Alzheimer’s disease reported the beneficial effects of both compounds, suggesting that their use in treatments may be a promising strategy in the management of neurodegenerative diseases aimed at maintaining mitochondrial homeostasis and ameliorating glia-mediated neuroinflammation.

Protective Effects of Liquiritigenin against Cisplatin-Induced Nephrotoxicity via NRF2/SIRT3-Mediated Improvement of Mitochondrial Function

Acute kidney injury (AKI) induced by cisplatin (CP), a first-line anticancer drug for chemotherapy, is common. To date, there is an urgent need to find effective treatments to reduce the nephrotoxicity caused by CP. Meanwhile, the restoration of mitochondrial dysfunction shows potential to be used as an adjunct to conventional therapeutic strategies. This study found that liquiritigenin can ameliorate mitochondrial dysfunction and acute kidney injury induced by CP in mice. The intraperitoneal injection of 15 mg/kg body weight liquiritigenin for 2 days markedly protected against CP-induced mitochondrial dysfunction, restored renal tubule and mitochondrial morphology, decreased blood Scr and BUN levels, and decreased cell apoptosis. Furthermore, the elevated expression of SIRT3 induced by liquiritigenin, which can be upregulated by NRF2, was confirmed in vivo and in vitro. The underlying protective mechanisms of liquiritigenin in CP-induced nephrotoxicity were then investigated. Molecular docking results showed that liquiritigenin has potent binding activities to KEAP1, GSK-3β and HRD1. Further results showed that liquiritigenin induced the nuclear translocation of NRF2 and increased the levels of mitochondrial bioenergetics-related protein such as PGC-1α, and TFAM, which are related to NRF2 activity and mitochondrial biogenesis. In addition, liquiritigenin was found to possibly reverse the decrease in BCL2/BAX ratio induced by CP in live cultured renal tubule epithelial cells. Collectively, these results indicated that liquiritigenin could be used as a potential nephroprotective agent to protect against cisplatin-induced acute kidney injury in a NRF2-dependent manner by improving mitochondria function.

Metabolomics of oxidative stress: Nrf2 independent depletion of NAD or increases of sugar alcohols

Nrf2 encodes a transcription factor best known for regulating the expression of antioxidant and detoxification genes. Recent evidence suggested that Nrf2 mediates metabolic reprogramming in cancer cells. However, the role of Nrf2 in the biochemical metabolism of cardiac cells has not been studied. Using LC-MS/MS-based metabolomics, we addressed whether knocking out the Nrf2 gene in AC16 human cardiomyocytes affects metabolic reprogramming by oxidative stress. Profiling the basal level metabolites showed an elevated pentose phosphate pathway and increased levels of sugar alcohols, sorbitol, L-arabitol, xylitol and xylonic acid, in Nrf2 KO cells. With sublethal levels of oxidative stress, depletion of NAD, an increase of GDP and elevation of sugar alcohols, sorbitol and dulcitol, were detected in parent wild type (WT) cells. Knocking out Nrf2 did not affect these changes. Biochemical assays confirmed depletion of NAD in WT and Nrf2 KO cells due to H₂O₂ treatment. These data support that although Nrf2 deficiency caused baseline activation of the pentose phosphate pathway and sugar alcohol synthesis, a brief exposure to none-lethal doses of H₂O₂ caused NAD depletion in an Nrf2 independent manner. Loss of NAD may contribute to oxidative stress associated cell degeneration as observed with aging, diabetes and heart failure.