Regulation of Nrf2 by Mitochondrial Reactive Oxygen Species in Physiology and Pathology

The Interplay Between Mitochondrial Reactive Oxygen Species, Endoplasmic Reticulum Stress, and Nrf2 Signaling in Cardiometabolic Health

Significance: Mitochondria-derived reactive oxygen species (mtROS) are by-products of normal physiology that may disrupt cellular redox homeostasis on a regular basis. Nonetheless, failure to resolve sustained mitochondrial stress to mitigate high levels of mtROS might contribute to the etiology of numerous pathological conditions, such as obesity, insulin resistance, and cardiovascular disease (CVD). Recent Advances: Notably, recent studies have demonstrated that moderate mitochondrial stress might result in the induction of different stress response pathways that ultimately improve the organism's ability to deal with subsequent stress, a process termed mitohormesis. mtROS have been shown to play a key role in regulating this adaptation. Critical Issue: mtROS regulate the convergence of different signaling pathways that, when disturbed, might impair cardiometabolic health. Conversely, mtROS seem to be required to mediate activation of prosurvival pathways, contributing to improved cardiometabolic fitness. In the present review, we will primarily focus on the role of mtROS in the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway and examine the role of endoplasmic reticulum (ER) stress in coordinating the convergence of ER stress and oxidative stress signaling through activation of Nrf2 and activating transcription factor 4 (ATF4). Future Directions: The mechanisms underlying cardiometabolic protection in response to mitochondrial stress have only started to be investigated. Integrated understanding of how mtROS and ER stress cooperatively promote activation of prosurvival pathways might shed mechanistic insight into the role of mitohormesis in mediating cardiometabolic protection and might inform future therapeutic avenues for the treatment of metabolic diseases contributing to CVD. Antioxid. Redox Signal. 35, 252-269.

Senolytics and senomorphics: Natural and synthetic therapeutics in the treatment of aging and chronic diseases

Cellular senescence is a heterogeneous process guided by genetic, epigenetic and environmental factors, characterizing many types of somatic cells. It has been suggested as an aging hallmark that is believed to contribute to aging and chronic diseases. Senescent cells (SC) exhibit a specific senescence-associated secretory phenotype (SASP), mainly characterized by the production of proinflammatory and matrix-degrading molecules. When SC accumulate, a chronic, systemic, low-grade inflammation, known as inflammaging, is induced. In turn, this chronic immune system activation results in reduced SC clearance thus establishing a vicious circle that fuels inflammaging. SC accumulation represents a causal factor for various age-related pathologies. Targeting of several aging hallmarks has been suggested as a strategy to ameliorate healthspan and possibly lifespan. Consequently, SC and SASP are viewed as potential therapeutic targets either through the selective killing of SC or the selective SASP blockage, through natural or synthetic compounds. These compounds are members of a family of agents called senotherapeutics divided into senolytics and senomorphics. Few of them are already in clinical trials, possibly representing a future treatment of age-related pathologies including diseases such as atherosclerosis, osteoarthritis, osteoporosis, cancer, diabetes, neurodegenerative diseases such as Alzheimer's disease, cardiovascular diseases, hepatic steatosis, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis and age-related macular degeneration. In this review, we present the already identified senolytics and senomorphics focusing on their redox-sensitive properties. We describe the studies that revealed their effects on cellular senescence and enabled their nomination as novel anti-aging agents. We refer to the senolytics that are already in clinical trials and we present various adverse effects exhibited by senotherapeutics so far. Finally, we discuss aspects of the senotherapeutics that need improvement and we suggest the design of future senotherapeutics to target specific redox-regulated signaling pathways implicated either in the regulation of SASP or in the elimination of SC.

Effects of Bergamot Polyphenols on Mitochondrial Dysfunction and Sarcoplasmic Reticulum Stress in Diabetic Cardiomyopathy

Cardiovascular disease is the leading cause of death and disability in the Western world. In order to safeguard the structure and the functionality of the myocardium, it is extremely important to adequately support the cardiomyocytes. Two cellular organelles of cardiomyocytes are essential for cell survival and to ensure proper functioning of the myocardium: mitochondria and the sarcoplasmic reticulum. Mitochondria are responsible for the energy metabolism of the myocardium, and regulate the processes that can lead to cell death. The sarcoplasmic reticulum preserves the physiological concentration of the calcium ion, and triggers processes to protect the structural and functional integrity of the proteins. The alterations of these organelles can damage myocardial functioning. A proper nutritional balance regarding the intake of macronutrients and micronutrients leads to a significant improvement in the symptoms and consequences of heart disease. In particular, the Mediterranean diet, characterized by a high consumption of plant-based foods, small quantities of red meat, and high quantities of olive oil, reduces and improves the pathological condition of patients with heart failure. In addition, nutritional support and nutraceutical supplementation in patients who develop heart failure can contribute to the protection of the failing myocardium. Since polyphenols have numerous beneficial properties, including anti-inflammatory and antioxidant properties, this review gathers what is known about the beneficial effects of polyphenol-rich bergamot fruit on the cardiovascular system. In particular, the role of bergamot polyphenols in mitochondrial and sarcoplasmic dysfunctions in diabetic cardiomyopathy is reported.

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.

Oxidative Stress-A Key Player in the Course of Alcohol-Related Liver Disease

Oxidative stress is known to be an inseparable factor involved in the presentation of liver disorders. Free radicals interfere with DNA, proteins, and lipids, which are crucial in liver metabolism, changing their expression and biological functions. Additionally, oxidative stress modifies the function of micro-RNAs, impairing the metabolism of hepatocytes. Free radicals have also been proven to influence the function of certain transcriptional factors and to alter the cell cycle. The pathological appearance of alcohol-related liver disease (ALD) constitutes an ideal example of harmful effects due to the redox state. Finally, ethanol-induced toxicity and overproduction of free radicals provoke irreversible changes within liver parenchyma. Understanding the underlying mechanisms associated with the redox state in the course of ALD creates new possibilities of treatment for patients. The future of hepatology may become directly dependent on the effective action against reactive oxygen species. This review summarizes current data on the redox state in the natural history of ALD, highlighting the newest reports on this topic.

Chronic Inflammation in Chronic Kidney Disease Progression: Role of Nrf2

Despite recent advances in the management of chronic kidney disease (CKD), morbidity and mortality rates in these patients remain high. Although pressure-mediated injury is a well-recognized mechanism of disease progression in CKD, emerging data indicate that an intermediate phenotype involving chronic inflammation, oxidative stress, hypoxia, senescence, and mitochondrial dysfunction plays a key role in the etiology, progression, and pathophysiology of CKD. A variety of factors promote chronic inflammation in CKD, including oxidative stress and the adoption of a proinflammatory phenotype by resident kidney cells. Regulation of proinflammatory and anti-inflammatory factors through NF-κB- and nuclear factor, erythroid 2 like 2 (Nrf2)-mediated gene transcription, respectively, plays a critical role in the glomerular and tubular cell response to kidney injury. Chronic inflammation contributes to the decline in glomerular filtration rate (GFR) in CKD. Whereas the role of chronic inflammation in diabetic kidney disease (DKD) has been well-elucidated, there is now substantial evidence indicating unresolved inflammatory processes lead to fibrosis and eventual end-stage kidney disease (ESKD) in several other diseases, such as Alport syndrome, autosomal-dominant polycystic kidney disease (ADPKD), IgA nephropathy (IgAN), and focal segmental glomerulosclerosis (FSGS). In this review, we aim to clarify the mechanisms of chronic inflammation in the pathophysiology and disease progression across the spectrum of kidney diseases, with a focus on Nrf2.

The Function of the Hypothalamic-Pituitary-Adrenal Axis During Experimental Autoimmune Encephalomyelitis: Involvement of Oxidative Stress Mediators

Multiple sclerosis (MS) is an inflammatory, demyelinating disease with an unknown origin. Previous studies showed the involvement of the hypothalamic–pituitary–adrenal (HPA) axis to susceptibility to autoimmune diseases, including MS, and its best-characterized animal model, experimental autoimmune encephalomyelitis (EAE). During MS/EAE, innate immune cells are activated and release cytokines and other inflammatory mediators, leading to a vicious cycle of inflammation. In response to inflammation, the activated HPA axis modulates immune responses via glucocorticoid activity. Because the mechanisms involving oxidative stress to the HPA axis are relatively unrevealed, in this study, we investigate the inflammatory and oxidative stress status of HPA axis during EAE. Our results reveal an upregulation of Pomc gene expression, followed by POMC and ACTH protein increase at the peak of the EAE in the pituitary. Also, prostaglandins are well-known contributors of HPA axis activation, which increases during EAE at the periphery. The upregulated Tnf expression in the pituitary during the peak of EAE occurred. This leads to the activation of oxidative pathways, followed by upregulation of inducible NO synthase expression. The reactive oxidant/nitrosative species (ROS/RNS), such as superoxide anion and NO, increase their levels at the onset and peak of the disease in the pituitary and adrenal glands, returning to control levels at the end of EAE. The corticotrophs in the pituitary increased in number and volume at the peak of EAE that coincides with high lipid peroxidation levels. The expression of MC2R in the adrenal glands increases at the peak of EAE, where strong induction of superoxide anion and malondialdehyde (MDA), reduced total glutathione (GSH) content, and catalase activity occurred at the peak and end of EAE compared with controls. The results obtained from this study may help in understanding the mechanisms and possible pharmacological modulation in MS and demonstrate an effect of oxidative stress exposure in the HPA activation during the course of EAE.

Mild Mitochondrial Uncoupling Decreases Experimental Atherosclerosis, A Proof of Concept

Aim: Atherosclerosis is responsible for high morbidity and mortality rates around the world. Local arterial oxidative stress is involved in all phases of atherosclerosis development. Mitochondria is a relevant source of the oxidants, particularly under certain risky conditions, such as hypercholesterolemia. The aim of this study was to test whether lowering the production of mitochondrial oxidants by induction of a mild uncoupling can reduce atherosclerosis in hypercholesterolemic LDL receptor knockout mice.

Methods: The mice were chronically treated with very low doses of DNP (2,4-dinitrophenol) and metabolic, inflammatory and redox state markers and atherosclerotic lesion sizes were determined.

Results: The DNP treatment did not change the classical atherosclerotic risk markers, such as plasma lipids, glucose homeostasis, and fat mass, as well as systemic inflammatory markers. However, the DNP treatment diminished the production of mitochondrial oxidants, systemic and tissue oxidative damage markers, peritoneal macrophages and aortic rings oxidants generation. Most importantly, development of spontaneous and diet-induced atherosclerosis (lipid and macrophage content) were significantly decreased in the DNP-treated mice. In vitro, DNP treated peritoneal macrophages showed decreased H₂O₂ production, increased anti-inflammatory cytokines gene expression and secretion, increased phagocytic activity, and decreased LDL-cholesterol uptake.

Conclusions: These findings are a proof of concept that activation of mild mitochondrial uncoupling is sufficient to delay the development of atherosclerosis under the conditions of hypercholesterolemia and oxidative stress. These results promote future approaches targeting mitochondria for the prevention or treatment of atherosclerosis.

The Protective Effects of Sulforaphane on High-Fat Diet-Induced Obesity in Mice Through Browning of White Fat

Background: Sulforaphane (SFN), an isothiocyanate naturally occurring in cruciferous vegetables, is a potent indirect antioxidant and a promising agent for the control of metabolic disorder disease. The glucose intolerance and adipogenesis induced by diet in rats was inhibited by SFN. Strategies aimed at induction of brown adipose tissue (BAT) could be a potentially useful way to against obesity. However, in vivo protective effect of SFN against obesity by browning white adipocyte has not been reported. Our present study is aimed at evaluation the efficacy of the SFN against the high-fat induced-obesity mice and investigating the potential mechanism.

Methods: High-Fat Diet-induced obese female C57BL/6 mice were intraperitoneally injected with SFN (10 mg/kg) daily. Body weight was recorded every 3 days. 30 days later, glucose tolerance test (GTT) and insulin tolerance test (ITT) were performed. At the end of experiment, fat mass were measured and the adipogenesis as well as browning associated genes expression in white adipose tissue (WAT) were determined by RT-qPCR and western blot. Histological examination of the adipose tissue samples were carried out with hematoxylin–eosin (HE) staining and immunofluorescence staining method. In vitro, pre-adipocytes C3H10T1/2 were treated with SFN to investigate the direct effects on adipogenesis.

Results: SFN suppressed HFD-induced body weight gain and reduced the size of fat cells in mice. SFN suppressed the expression of key genes in adipogenesis, inhibited lipid accumulation in C3H10T1/2 cells, increased the expression of brown adipocyte-specific markers and mitochondrial biogenesis in vivo and in vitro, and decreased cellular and mitochondrial oxidative stress. These results suggested that SFN, as a nutritional factor, has great potential role in the battle against obesity by inducing the browning of white fat.

Conclusion: SFN could significantly decrease the fat mass, and improve glucose metabolism and increase insulin sensitivity of HFD-induced obese mice by promoting the browning of white fat and enhancing the mitochondrial biogenesis in WAT. Our study proves that SFN could serve as a potential medicine in anti-obesity and related diseases.

Redox imbalance in Crohn's disease patients is modulated by Azathioprine

Background

Crohn's disease (CD) is a chronic inflammatory disease without a specific cause. Inflammation in these patients can disturb the oxidants/antioxidants balance and results in oxidative stress that plays a destructive role. This study aimed to evaluate the gene expression of sod1, sod2, cat, nrf2 and gp91phox in CD patients before and after Azathioprine (Aza) consumption.

Method

Peripheral bloodmononuclear cells (PBMCs) were separated from CD patients (n= 15, mean age = 33.6 ± 1.8) before and after treatment with Aza and healthy controls (n= 15, mean age = 31.5 ± 1.2). The expression levels of sod1, sod2, cat, nrf2 and gp91phox were measured in byusing real-time qRT-PCR technique.

Result

The expression levels of gp91phox (P-value < 0.001), cat (P-value < 0.05), sod1 (P-value < 0.001), nrf2 (P-value < 0.001) were significantly increased compared to control group. Following treatment with Aza, the decreased expression levels of gp91phox (P-value < 0.05), cat (P-value < 0.05), sod1(P-value < 0.001) and nrf2 (P-value < 0.001) were observed in CD patients.

Conclusion

Overall, our results showed that prescription of Azathioprine can lead to the altered expression of redox system-related genes in patients with CD.

EVs from BALF-Mediators of Inflammation and Potential Biomarkers in Lung Diseases

Extracellular vesicles (EVs) have been identified as key messengers of intracellular communication in health and disease, including the lung. EVs that can be found in bronchoalveolar lavage fluid (BALF) are released by multiple cells of the airways including bronchial epithelial cells, endothelial cells, alveolar macrophages, and other immune cells, and they have been shown to mediate proinflammatory signals in many inflammatory lung diseases. They transfer complex molecular cargo, including proteins, cytokines, lipids, and nucleic acids such as microRNA, between structural cells such as pulmonary epithelial cells and innate immune cells such as alveolar macrophages, shaping mutually their functions and affecting the alveolar microenvironment homeostasis. Here, we discuss this distinct molecular cargo of BALF-EVs in the context of inducing and propagating inflammatory responses in particular acute and chronic lung disorders. We present different identified cellular interactions in the inflammatory lung via EVs and their role in lung pathogenesis. We also summarize the latest studies on the potential use of BALF-EVs as diagnostic and prognostic biomarkers of lung diseases, especially of lung cancer.

Amphora algae with low-level ionizing radiation exposure ameliorate D-galactosamine-induced inflammatory impairment in rat kidney

d-Galactosamine (d-GalN) is a well-known toxin that causes many metabolic and morphological abnormalities resulting in advanced renal failure and liver damage. Occupational exposure to low-level ionizing radiation (<1 Gy) was shown to enhance cell protection via attenuating an established inflammatory process. The present study was therefore aimed to investigate the protective impact of Amphora coffaeiformis extract and low dose gamma radiation against d-GalN induced renal damage in rats. Forty-eight adult male Swiss albino rats were distributed equally into eight groups. The measurements included antioxidants activities (superoxide dismutase, catalase and glutathione peroxidase) as well as lipid peroxidation level in kidney tissue. Also, kidney function tests and inflammatory markers (tumor necrosis factor alpha and nuclear factor kappa-light-chain-enhancer of activated B cells) were measured. Additionally, relative quantification of kidney nuclear factor erythroid 2-related factor 2 (Nrf-2) gene was estimated. Histopathological examination was also performed in kidney tissue. The results revealed decreases in antioxidant activities and downregulation of Nrf-2 expression accompanied by increases in lipid peroxidation level, kidney function tests and inflammatory markers in d-GaIN group. The treatment with Amphora algal extract and low dose gamma radiation ameliorated the previous measurements which were harmony with histopathological findings. In conclusion, A coffaeiformis extract and low dose gamma radiation provided marked functional and histological effects in the treating acute renal damage induced by d-GalN in rats.

Loss of QKI in macrophage aggravates inflammatory bowel disease through amplified ROS signaling and microbiota disproportion

Inflammatory bowel disease (IBD) is a refractory chronic inflammatory illness of the gastrointestinal (GI) tract. Macrophage exerts an important role in IBD development. QKI, as an RNA binding protein, was related with inflammatory responses in bacterial infections by regulating the polarization of macrophages. Therefore, we suspected that QKI-regulated macrophages have the potential to play a certain role in IBD and the underlying mechanism. Our results demonstrated that the mice with macrophage-specific deletion of QKI induced with dextran sodium sulfate (DSS) are more susceptible to IBD development, exhibited a severe leaky gut barrier phenotype and higher intense oxidative stress, which are rescued by treating with butylated hydroxyanisole (BHA), an agonist of NRF2. Mechanically, we observed that Keap1 mRNA in the nucleus was exported to the cytoplasm after LPS stimuli in parallel with QKI reductions, and the removal of QKI by shRNA facilitated Keap1 mRNA nuclear exporting and expression in cytoplasm, consequently NRF2 activation in nucleus was weakened, and led to the impaired antioxidant abilities. In addition, mice models of fecal microbiota transplant (FMT) and the co-culturing of mice epithelia cells with feces derived from the DSS-treated QKI-deficit mice revealed consistently aggravated colitis along with a severe oxidative stress; 16S sequencing analysis substantiated the altered compositions of commensal bacteria too. Overall, the current study represents the first effort to explore the anti-oxidant role of QKI in the intestinal macrophage via post-transcriptional regulation of Keap1 mRNA localization and the relevant NRF2 antioxidant signaling, and the disproportional changes in the microbiota were attributable to the mediation of pathogenic damage in the IBD development of QKI-deficit mice.

Reactive oxygen species modulators in pulmonary medicine

Adapted to effectively capture oxygen from inhaled air and deliver it to all other parts of the body, the lungs constitute the organ with the largest surface area. This makes the lungs more susceptible to airborne pathogens and pollutants that mediate pathologies through generation of reactive oxygen species (ROS). One pathological consequence of excessive levels of ROS production is pulmonary diseases that account for a large number of mortality and morbidity in the world. Of the various mechanisms involved in pulmonary disease pathogenesis, mitochondrial dysfunction takes prominent importance. Herein, we briefly describe the significance of oxidative stress caused by ROS in pulmonary diseases and some possible therapeutic strategies.

Transcriptional Regulation of ROS Homeostasis by the ERR Subfamily of Nuclear Receptors

Reactive oxygen species (ROS) such as superoxide anion (O₂^•-) and hydrogen peroxide (H₂O₂) are generated endogenously by processes such as mitochondrial oxidative phosphorylation, or they may arise from exogenous sources like bacterial invasion. ROS can be beneficial (oxidative eustress) as signaling molecules but also harmful (oxidative distress) to cells when ROS levels become unregulated in response to physiological, pathological or pharmacological insults. Indeed, abnormal ROS levels have been shown to contribute to the etiology of a wide variety of diseases. Transcriptional control of metabolic genes is a crucial mechanism to coordinate ROS homeostasis. Therefore, a better understanding of how ROS metabolism is regulated by specific transcription factors can contribute to uncovering new therapeutic strategies. A large body of work has positioned the estrogen-related receptors (ERRs), transcription factors belonging to the nuclear receptor superfamily, as not only master regulators of cellular energy metabolism but, most recently, of ROS metabolism. Herein, we will review the role played by the ERRs as transcriptional regulators of ROS generation and antioxidant mechanisms and also as ROS sensors. We will assess how the control of ROS homeostasis by the ERRs can be linked to physiology and disease and the possible contribution of manipulating ERR activity in redox medicine.

Nrf2 Signaling Pathway in Chemoprotection and Doxorubicin Resistance: Potential Application in Drug Discovery

Doxorubicin (DOX) is extensively applied in cancer therapy due to its efficacy in suppressing cancer progression and inducing apoptosis. After its discovery, this chemotherapeutic agent has been frequently used for cancer therapy, leading to chemoresistance. Due to dose-dependent toxicity, high concentrations of DOX cannot be administered to cancer patients. Therefore, experiments have been directed towards revealing underlying mechanisms responsible for DOX resistance and ameliorating its adverse effects. Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling is activated to increase levels of reactive oxygen species (ROS) in cells to protect them against oxidative stress. It has been reported that Nrf2 activation is associated with drug resistance. In cells exposed to DOX, stimulation of Nrf2 signaling protects cells against cell death. Various upstream mediators regulate Nrf2 in DOX resistance. Strategies, both pharmacological and genetic interventions, have been applied for reversing DOX resistance. However, Nrf2 induction is of importance for alleviating side effects of DOX. Pharmacological agents with naturally occurring compounds as the most common have been used for inducing Nrf2 signaling in DOX amelioration. Furthermore, signaling networks in which Nrf2 is a key player for protection against DOX adverse effects have been revealed and are discussed in the current review.

KLF9 regulates PRDX6 expression in hyperglycemia-aggravated bupivacaine neurotoxicity

BACKGROUND

Neurotoxicity induced by local anesthetics (LAs) is potentially life threatening, especially for patients with underlying diseases like diabetes. The anesthetic bupivacaine (Bup) has been reported to induce neurotoxicity mediated by reactive oxygen species (ROS), which is aggravated by hyperglycemia. Krüppel-like factor 9 (KLF9), an axon growth-suppressing transcription factor, plays a key role in neuronal maturation and promotes oxidative stress. This study was designed to investigate whether and how KLF9 regulates ROS levels related to LA neurotoxicity under hyperglycemic conditions.

METHODS

Klf9/GFP ShRNA (LV Sh-Klf9) was used to achieve stable Klf9 knockdown in the SH-SY5Y cell line. KLF9-deficient and normal cells were cultured under normal or high-glucose (HG) culture conditions and then exposed to Bup. Cell viability, intracellular and mitochondrial ROS, and mitochondrial membrane potential (ΔΨm) were detected to examine the role of KLF9. Thereafter, KLF9-deficient and normal cells were pretreated with small-interfering RNA targeting peroxiredoxin 6 (siRNA-Prdx6) to determine if PRDX6 was the target protein in HG-aggravated Bup neurotoxicity.

RESULTS

The mRNA and protein levels of KLF9 were increased after Bup and hyperglycemia treatment. In addition, cell survival and mitochondrial function were significantly improved, and ROS production was decreased after Sh-Klf9 treatment compared with Sh-Ctrl. Furthermore, the expression of PRDX6 was suppressed by Bup in hyperglycemic cultures and was upregulated in the Sh-Klf9 group. Moreover, the protection provided by KLF9 deficiency for cell survival, the increase in ROS production in cells and mitochondria, and the disruption of mitochondrial function were abolished by Prdx6 knockdown.

CONCLUSIONS

The results of this study demonstrated that hyperglycemia aggravated Bup neurotoxicity by upregulating KLF9 expression, which repressed the antioxidant PRDX6 and led to mitochondrial dysfunction, ROS burst, and cell death. Understanding this mechanism may, thus, offer valuable insights for the prevention and treatment of neurotoxicity induced by LAs, especially in diabetic patients.

Brazilin prevents against myocardial ischemia-reperfusion injury through the modulation of Nrf2 via the PKC signaling pathway

Background

Brazilin, a major ingredient of Caesalpinia sappan L., possesses multiple pharmaceutical activities, although whether or not brazilin exerts any protective effect on myocardial ischemia-reperfusion injury (MIRI) has not yet been reported. The present study determined the cardioprotective effects of brazilin, and elucidated the role of nuclear factor E2-associated factor 2 (Nrf2) in this process.

Methods

Following treatment with brazilin, H9c2 cells were subjected to 6 h of hypoxia/3 h of reoxygenation. CCK-8 assay and flow cytometry were employed to detect cell viability and apoptosis, respectively. Furthermore, after brazilin treatment, isolated rat hearts underwent 30 min of ischemia, followed by 90 min of reperfusion. Triphenyltetrazolium chloride (TTC) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining were performed to measure myocardial infarct size and apoptosis, respectively. The changes in the levels of proteins were detected by western blotting.

Results

Brazilin treatment dose-dependently led to a significant enhancement in cell viability, a reduction in myocardial infarct size, and a decrease in release of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH). Moreover, brazilin also remarkably inhibited apoptosis and led to various improvements in cardiac function. Additionally, brazilin treatment caused a marked alleviation of oxidative stress, as evidenced by the fact that brazilin reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), while enhancing the activities of superoxide dismutase (SOD) and glutathione peroxidase (GXH-Px). Mechanistically, it was found that brazilin induced Nrf2 nuclear translocation, with a concomitant upregulation of both heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase (NQO1) expression. Furthermore, the phosphorylation level and transcriptional activity of Nrf2 were enhanced by brazilin, although these enhancements were abrogated by treatment with a protein kinase C (PKC) inhibitor. Finally, it was observed that the protective effects of brazilin could be negated through inhibition of Nrf2, which suggested that the cardioprotection afforded by brazilin was Nrf2-dependent.

Conclusions

Taken together, our results have demonstrated that brazilin may afford protection against MIRI through the activation of Nrf2 via the PKC signaling pathway. These results may lay the foundation for the further use of brazilin in the prevention of MIRI in clinical practice.

The Effect of Acute Aerobic Exercise on Redox Homeostasis and Mitochondrial Function of Rat White Adipose Tissue

Physical exercise is characterized by an increase in physical and metabolic demand in face of physical stress. It is reported that a single exercise session induces physiological responses through redox signaling to increase cellular function and energy support in diverse organs. However, little is known about the effect of a single bout of exercise on the redox homeostasis and cytoprotective gene expression of white adipose tissue (WAT). Thus, we aimed at evaluating the effects of acute aerobic exercise on WAT redox homeostasis, mitochondrial metabolism, and cytoprotective genic response. Male Wistar rats were submitted to a single moderate-high running session (treadmill) and were divided into five groups: control (CTRL, without exercise), and euthanized immediately (0 h), 30 min, 1 hour, or 2 hours after the end of the exercise session. NADPH oxidase activity was higher in 0 h and 30 min groups when compared to CTRL group. Extramitochondrial ROS production was higher in 0 h group in comparison to CTRL and 2 h groups. Mitochondrial respiration in phosphorylative state increased in 0 h group when compared to CTRL, 30 min, 1, and 2 h groups. On the other hand, mitochondrial ATP production was lower in 0 h in comparison to 30 min group, increasing in 1 and 2 h groups when compared to CTRL and 0 h groups. CAT activity was lower in all exercised groups when compared to CTRL. Regarding oxidative stress biomarkers, we observed a decrease in reduced thiol content in 0 h group compared to CTRL and 2 h groups, and higher levels of protein carbonylation in 0 and 30 min groups in comparison to the other groups. The levels returned to basal condition in 2 h group. Furthermore, aerobic exercise increased NRF2, GPX2, HMOX1, SOD1, and CAT mRNA levels. Taken together, our results suggest that one session of aerobic exercise can induce a transient prooxidative state in WAT, followed by an increase in antioxidant and cytoprotective gene expression.

The Mitochondrial Permeability Transition: Nexus of Aging, Disease and Longevity

The activity of the mitochondrial permeability transition pore, mPTP, a highly regulated multi-component mega-channel, is enhanced in aging and in aging-driven degenerative diseases. mPTP activity accelerates aging by releasing large amounts of cell-damaging reactive oxygen species, Ca²⁺ and NAD⁺. The various pathways that control the channel activity, directly or indirectly, can therefore either inhibit or accelerate aging or retard or enhance the progression of aging-driven degenerative diseases and determine lifespan and healthspan. Autophagy, a catabolic process that removes and digests damaged proteins and organelles, protects the cell against aging and disease. However, the protective effect of autophagy depends on mTORC2/SKG1 inhibition of mPTP. Autophagy is inhibited in aging cells. Mitophagy, a specialized form of autophagy, which retards aging by removing mitochondrial fragments with activated mPTP, is also inhibited in aging cells, and this inhibition leads to increased mPTP activation, which is a major contributor to neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. The increased activity of mPTP in aging turns autophagy/mitophagy into a destructive process leading to cell aging and death. Several drugs and lifestyle modifications that enhance healthspan and lifespan enhance autophagy and inhibit the activation of mPTP. Therefore, elucidating the intricate connections between pathways that activate and inhibit mPTP, in the context of aging and degenerative diseases, could enhance the discovery of new drugs and lifestyle modifications that slow aging and degenerative disease.

Nrf2 is activated by disruption of mitochondrial thiol homeostasis but not by enhanced mitochondrial superoxide production

The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) regulates the expression of genes involved in antioxidant defenses to modulate fundamental cellular processes such as mitochondrial function and GSH metabolism. Previous reports proposed that mitochondrial reactive oxygen species production and disruption of the GSH pool activate the Nrf2 pathway, suggesting that Nrf2 senses mitochondrial redox signals and/or oxidative damage and signals to the nucleus to respond appropriately. However, until now, it has not been possible to disentangle the overlapping effects of mitochondrial superoxide/hydrogen peroxide production as a redox signal from changes to mitochondrial thiol homeostasis on Nrf2. Recently, we developed mitochondria-targeted reagents that can independently induce mitochondrial superoxide and hydrogen peroxide production mitoParaquat (MitoPQ) or selectively disrupt mitochondrial thiol homeostasis MitoChlorodinitrobenzoic acid (MitoCDNB). Using these reagents, here we have determined how enhanced generation of mitochondrial superoxide and hydrogen peroxide or disruption of mitochondrial thiol homeostasis affects activation of the Nrf2 system in cells, which was assessed by the Nrf2 protein level, nuclear translocation, and expression of its target genes. We found that selective disruption of the mitochondrial GSH pool and inhibition of its thioredoxin system by MitoCDNB led to Nrf2 activation, whereas using MitoPQ to enhance the production of mitochondrial superoxide and hydrogen peroxide alone did not. We further showed that Nrf2 activation by MitoCDNB requires cysteine sensors of Kelch-like ECH-associated protein 1 (Keap1). These findings provide important information on how disruption to mitochondrial redox homeostasis is sensed in the cytoplasm and signaled to the nucleus.

Isoliquiritigenin prevents hyperglycemia-induced renal injuries by inhibiting inflammation and oxidative stress via SIRT1-dependent mechanism

Diabetic nephropathy (DN) as a global health concern is closely related to inflammation and oxidation. Isoliquiritigenin (ISL), a natural flavonoid compound, has been demonstrated to inhibit inflammation in macrophages. Herein, we investigated the effect of ISL in protecting against the injury in STZ-induced type 1 DN and in high glucose-induced NRK-52E cells. In this study, it was revealed that the administration of ISL not only ameliorated renal fibrosis and apoptosis, but also induced the deterioration of renal function in diabetic mice. Mediated by MAPKs and Nrf-2 signaling pathways, respectively, upstream inflammatory response and oxidative stress were neutralized by ISL in vitro and in vivo. Moreover, as further revealed by the results of molecular docking, sirtuin 1 (SIRT1) binds to ISL directly, and the involvement of SIRT1 in ISL-mediated renoprotective effects was confirmed by studies using in vitro models of SIRT1 overexpression and knockdown. In summary, by reducing inflammation and oxidative stress, ISL has a significant pharmacological effect on the deterioration of DN. The benefits of ISL are associated with the direct binding to SIRT1, the inhibition of MAPK activation, and the induction of Nrf-2 signaling, suggesting the potential of ISL for DN treatment.

Dental resin monomers induce early and potent oxidative damage on human odontoblast-like cells

Resin-based dental materials consist of filler particles and different monomers that are light cured in situ to re-establish dental function and aesthetics. Due to the degree of conversion of adhesive polymers, the monomers triethyleneglycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) are released in relatively high amounts and are susceptible to degradation, acting as bioactive compounds and affecting cell and tissues. This study aimed to assess the effect of HEMA and TEGDMA exposure on metabolic activity, membrane integrity, and cell survival of human odontoblast-like cell (hOLCs). Exposure to resin monomers for 24 h induced major changes in cell membrane integrity, metabolic activity, and survival, which were measured by the calcein method and lactate dehydrogenase release. Increased and early reactive oxygen species (ROS) production was observed leading to degradative oxidation of membrane lipids identified as malondialdehyde production. Severe alteration in mitochondria occurred due to transmembrane mitochondrial potential collapse, possibly inducing activation of apoptotic cell death. hOLCs exposure to resin monomers modified the cell redox potential, with consequences on membrane permeability and integrity, including mitochondrial function. Lipid peroxidation appears to be a key phenomenon for the membrane structures oxidation after HEMA and TEGDMA exposure, leading to cell death and cytotoxicity. hOLCs respond early by differential induction of adaptive mechanisms to maintain cell homeostasis. Modulation of oxidative stress-induced response involves the regulation of genes that encode for antioxidant proteins such as catalase and heme oxygenase-1; regulation that functions as a critical protection mechanism against oxidative cell damage induced by HEMA and TEGDMA. Ascorbic acid as an antioxidant substance mitigates the oxidative damage associated with exposure to monomers.

Activation of the Melanocortin-1 Receptor by NDP-MSH Attenuates Oxidative Stress and Neuronal Apoptosis through PI3K/Akt/Nrf2 Pathway after Intracerebral Hemorrhage in Mice

Oxidative stress and neuronal apoptosis play crucial roles in secondary brain injury (SBI) after intracerebral hemorrhage (ICH). Recently, Nle4-D-Phe7-α-melanocyte-stimulating hormone (NDP-MSH), a synthetic agonist of the melanocortin-1 receptor (Mc1r), has been proved to inhibit neuroinflammatory in several diseases. This study is aimed at exploring if NDP-MSH could reduce oxidative stress and neuronal apoptosis following ICH, as well as the potential mechanism. A mouse ICH model was induced by autologous blood injection. NDP-MSH was intraperitoneally injected at 1 h after ICH. Mc1r siRNA and PI3K inhibitor LY294002 were administrated to inhibit the expression of Mc1r and phosphorylation of PI3K, respectively. Neurological test, brain water content, enzyme-linked immunosorbent assay (ELISA), terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), immunofluorescence, and Western blot analysis were utilized in this study. The results exhibited that Mc1r was mainly expressed in neurons, and its level in the ipsilateral hemisphere was significantly elevated after ICH. NDP-MSH treatment significantly attenuated the neurological deficits and brain water content 24 hours after ICH, which was accompanied by the inhibition of oxidative stress and neuronal apoptosis. The administration of NDP-MSH after ICH significantly promoted the expression of Mc1r, p-PI3K, p-Akt, and p-Nrf2, followed by an increase of Bcl-2 and reduction of cleaved caspase-3. Conversely, downregulating the expression of Mc1r and phosphorylation of PI3K aggravated the neurological deficits and brain edema at 24 hours after ICH, meanwhile, the effect of NDP-MSH on the expression of Mc1r, p-PI3K, p-Akt, p-Nrf2, Bcl-2, and cleaved caspase 3 was also abolished. In conclusion, our data suggest that the activation of Mc1r by NDP-MSH ameliorates oxidative stress and neuronal apoptosis through the PI3K/Akt/Nrf2 signaling pathway after ICH in mice.

Dimethyl fumarate protects nucleus pulposus cells from inflammation and oxidative stress and delays the intervertebral disc degeneration

Lower back pain is a common problem in middle-aged and elderly people, and intervertebral disc degeneration (IVDD) is often the main cause. The present study aimed to explore the effects of dimethyl fumarate (DMF) on inflammation and oxidative stress in the intervertebral disc. C57/BL6 mice were used to construct an IVDD model by tail suspension and daily intraperitoneal injections of 10 mg/kg DMF were administered to analyze the effects of DMF on IVDD. In addition, human nucleus pulposus (NP) cells were cultured and stimulated cells with recombinant human IL-1β and DMF to examine the effects of DMF on inflammation and oxidative stress in NP cells. DMF significantly increased the intervertebral disc height index of mice and inhibited the degradation of the extracellular matrix of mouse NP tissue. In addition, DMF also decreased the expression of inflammatory factors [including IL-6, IL-8, matrix metalloproteinase (MMP)3 and MMP13] in NP cells. In terms of oxidative stress, DMF significantly increased the antioxidative stress response in NP cells and reduced endoplasmic reticulum stress. DMF also increased the activity of the nuclear factor erythroid 2-related factor (Nrf) 2/heme oxygenase (HO)-1 signaling pathway in NP cells and increased the phosphorylation of Akt. DMF also increased the anti-inflammatory and antioxidative ability of NP cells by promoting the activity of the Nrf2/HO-1 and PI3K/Akt signaling pathways, thus delaying IVDD.

Epigallocatechin Gallate Effectively Affects Senescence and Anti-SASP via SIRT3 in 3T3-L1 Preadipocytes in Comparison with Other Bioactive Substances

AIM

We investigated different bioactive compounds including epigallocatechin gallate (EGCG), anthocyanidin, resveratrol, phloretin, spermidine, butyrate, and β-hydroxybutyrate with regard to their effect on SIRT3 via NRF2 and modulation of the proinflammatory senescence-associated secretory phenotype (SASP) in senescence induced 3T3-L1 preadipocytes.

METHODS

For induction of senescence, 3T3-L1 preadipocytes were incubated with bromodeoxyuridine (BrdU) for 8 days. Cell cycle inhibition was observed, and β-galactosidase activity was measured. After BrdU treatment, cells were treated with different bioactive compounds in various concentrations for 96 h. ELISA was used for determining proinflammatory cytokine IL6 in SASP cells.

RESULTS

CDKN1a increased significantly after BrdU incubation compared to untreated control (p < 0.01). All secondary plant ingredients used for treatment, but not anthocyanidin 50 μM, decrease CDKN1a expression (p < 0.05), whereas most endogenous substances did not attenuate CDKN1a. IL6 secretion positively correlated with CDKN1a (p < 0.01), whereas EGCG could diminish both, IL6 and CDKN1a with the strongest effect (p < 0.01). Although NRF2 positively correlated with SIRT3 activation (p < 0.05), only resveratrol (p < 0.01) and anthocyanidin (p < 0.05) could activate NRF2 significantly. Solely anthocyanidin 50 μM (p < 0.05) and 100 μM (p < 0.01) and EGCG 50 μM (p < 0.01) could increase SIRT3 expression. Activation of SIRT3 with EGCG correlated with lowered IL6 secretion significantly (p < 0.05) but not with anthocyanidin.

CONCLUSION

Accumulation of senescent cells in adipose tissue plays an important role in obesity and age-related diseases. SIRT3, located in the mitochondria, can regulate ROS via different pathways. Thus, targeting SIRT3 activating compounds such as EGCG may delay senescence of cells and senescence induced inflammatory processes.

Small molecules regulating reactive oxygen species homeostasis for cancer therapy

Elevated intracellular reactive oxygen species (ROS) and antioxidant defense systems have been recognized as one of the hallmarks of cancer cells. Compared with normal cells, cancer cells exhibit increased ROS to maintain their malignant phenotypes and are more dependent on the "redox adaptation" mechanism. Thus, there are two apparently contradictory but virtually complementary therapeutic strategies for the regulation of ROS to prevent or treat cancer. The first strategy, that is, chemoprevention, is to prevent or reduce intracellular ROS either by suppressing ROS production pathways or by employing antioxidants to enhance ROS clearance, which protects normal cells from malignant transformation and inhibits the early stage of tumorigenesis. The second strategy is the ROS-mediated anticancer therapy, which stimulates intracellular ROS to a toxicity threshold to activate ROS-induced cell death pathways. Therefore, targeting the regulation of intracellular ROS-related pathways by small-molecule candidates is considered to be a promising treatment for tumors. We herein first briefly introduce the source and regulation of ROS, and then focus on small molecules that regulate ROS-related pathways and show efficacy in cancer therapy from the perspective of pharmacophores. Finally, we discuss several challenges in developing cancer therapeutic agents based on ROS regulation and propose the direction of future development.

Oxidative Stress in Cardiovascular Diseases

Reactive oxygen species (ROS) are subcellular messengers in signal transductions pathways with both beneficial and deleterious roles. ROS are generated as a by-product of mitochondrial respiration or metabolism or by specific enzymes such as superoxide dismutases, glutathione peroxidase, catalase, peroxiredoxins, and myeloperoxidases. Under physiological conditions, the low levels of ROS production are equivalent to their detoxification, playing a major role in cellular signaling and function. In pathological situations, particularly atherosclerosis or hypertension, the release of ROS exceeds endogenous antioxidant capacity, leading to cell death. At cardiovascular levels, oxidative stress is highly implicated in myocardial infarction, ischemia/reperfusion, or heart failure. Here, we will first detail the physiological role of low ROS production in the heart and the vessels. Indeed, ROS are able to regulate multiple cardiovascular functions, such as cell proliferation, migration, and death. Second, we will investigate the implication of oxidative stress in cardiovascular diseases. Then, we will focus on ROS produced by NAPDH oxidase or during endothelial or mitochondrial dysfunction. Given the importance of oxidative stress at the cardiovascular level, antioxidant therapies could be a real benefit. In the last part of this review, we will detail the new therapeutic strategies potentially involved in cardiovascular protection and currently under study.

Mitochondrial Reactive Oxygen Species: Double-Edged Weapon in Host Defense and Pathological Inflammation During Infection

Mitochondria are inevitable sources for the generation of mitochondrial reactive oxygen species (mtROS) due to their fundamental roles in respiration. mtROS were reported to be bactericidal weapons with an innate effector function during infection. However, the controlled generation of mtROS is vital for the induction of efficient immune responses because excessive production of mtROS with mitochondrial damage leads to sustained inflammation, resulting in pathological outcomes such as sepsis. Here, we discuss the beneficial and detrimental roles of mtROS in the innate immune system during bacterial, viral, and fungal infections. Recent evidence suggests that several pathogens have evolved multiple strategies to modulate mtROS for their own benefit. We are just beginning to understand the mechanisms by which mtROS generation is regulated and how mtROS affect protective and pathological responses during infection. Several agents/small molecules that prevent the uncontrolled production of mtROS are known to be beneficial in the maintenance of tissue homeostasis during sepsis. mtROS-targeted approaches need to be incorporated into preventive and therapeutic strategies against a variety of infections.

Bixin Confers Prevention against Ureteral Obstruction-Caused Renal Interstitial Fibrosis through Activation of the Nuclear Factor Erythroid-2-Related Factor2 Pathway in Mice

Bixin is a natural carotenoid isolated from the seeds of Bixa orellana, with numerous important pharmacological activities, including antioxidant and antifibrotic effects. The nuclear factor erythroid-2-related factor2 (Nrf2) signaling pathway induced by bixin is involved in the process. Excessive reactive oxygen species generation in tubular cells contributes to kidney interstitial fibrosis. The potential therapeutic strategy for bixin in alleviating kidney fibrosis remains largely unclear. In this study, we used unilateral ureteral obstruction (UUO) to establish a renal fibrotic model. Dramatic oxidative DNA damage occurs in kidneys, especially in tubular cells after UUO. In cultured tubular cells, bixin could induce Nrf2 signaling activation by suppressing Nrf2 ubiquitination and increasing its protein stability. Transforming growth factor beta 1-induced epithelial-to-mesenchymal transition (EMT) and extracellular matrix production were suppressed by bixin, and blockade of Nrf2 activation by small interfering RNA could largely reverse the protective effect of bixin. In vivo studies showed that administration of bixin induces Nrf2 signaling activation in tubular cells and markedly attenuates partial EMT of tubular cells and kidney interstitial fibrosis after subjecting to UUO. Together, this study implies that bixin may protect against kidney interstitial fibrosis through stimulating Nrf2 activation in renal tubular cells.

Role of Nrf2 and Its Activators in Cardiocerebral Vascular Disease

Cardiocerebral vascular disease (CCVD) is a common disease with high morbidity, disability, and mortality. Oxidative stress (OS) is closely related to the progression of CCVD. Abnormal redox regulation leads to OS and overproduction of reactive oxygen species (ROS), which can cause biomolecular and cellular damage. The Nrf2/antioxidant response element (ARE) signaling pathway is one of the most important defense systems against exogenous and endogenous OS injury, and Nrf2 is regarded as a vital pharmacological target. The complexity of the CCVD pathological process and the current difficulties in conducting clinical trials have hindered the development of therapeutic drugs. Furthermore, little is known about the role of the Nrf2/ARE signaling pathway in CCVD. Clarifying the role of the Nrf2/ARE signaling pathway in CCVD can provide new ideas for drug design. This review details the recent advancements in the regulation of the Nrf2/ARE system and its role and activators in common CCVD development.

Versatile role of curcumin and its derivatives in lung cancer therapy

Lung cancer is a main cause of death all over the world with a high incidence rate. Metastasis into neighboring and distant tissues as well as resistance of cancer cells to chemotherapy demand novel strategies in lung cancer therapy. Curcumin is a naturally occurring nutraceutical compound derived from Curcuma longa (turmeric) that has great pharmacological effects, such as anti-inflammatory, neuroprotective, and antidiabetic. The excellent antitumor activity of curcumin has led to its extensive application in the treatment of various cancers. In the present review, we describe the antitumor activity of curcumin against lung cancer. Curcumin affects different molecular pathways such as vascular endothelial growth factors, nuclear factor-κB (NF-κB), mammalian target of rapamycin, PI3/Akt, microRNAs, and long noncoding RNAs in treatment of lung cancer. Curcumin also can induce autophagy, apoptosis, and cell cycle arrest to reduce the viability and proliferation of lung cancer cells. Notably, curcumin supplementation sensitizes cancer cells to chemotherapy and enhances chemotherapy-mediated apoptosis. Curcumin can elevate the efficacy of radiotherapy in lung cancer therapy by targeting various signaling pathways, such as epidermal growth factor receptor and NF-κB. Curcumin-loaded nanocarriers enhance the bioavailability, cellular uptake, and antitumor activity of curcumin. The aforementioned effects are comprehensively discussed in the current review to further direct studies for applying curcumin in lung cancer therapy.

Sulforaphane protects against skeletal muscle dysfunction in spontaneous type 2 diabetic db/db mice

AIMS

Skeletal muscle diseases have become to be the most common complication in patients with type 2 diabetic mellitus (T2DM). However, the effective therapies against skeletal muscle diseases are not yet available. Sulforaphane (SFN) is an organic isothiocyanate found in cruciferous plants. Our aim was to explore whether SFN could attenuate the skeletal muscle diseases in spontaneous type 2 diabetic db/db mice.

MATERIALS AND METHODS

The db/m and littermate db/db mice were treated with SFN or dimethyl sulfoxide. The grip strength of mice was measured by a grasping forcing machine. The electron transmission microscopy was used to perform the skeletal muscle. The western blot was used to detect the nuclear factor E2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signal pathway related proteins, and inflammatory and apoptotic associated proteins. The mRNA levels of anti-inflammatory and anti-oxidative relative genes were detected by RT-QPCR.

KEY FINDINGS

We found that SFN could significantly increase the grip strength of the db/db mice. The lean mass and gastrocnemius mass were increased in the db/db mice after administration with SFN. Additionally, the db/db mice restored the skeletal muscle fiber organization after SFN treatment. Mechanistically, SFN could activate the Nrf2/HO-1 signal pathway, and downregulate the expression of inflammatory and apoptotic associated proteins. Furthermore, SFN could also regulate the mRNA levels of anti-inflammatory and anti-oxidative related genes.

SIGNIFICANCE

Our results demonstrated that SFN can protect against skeletal muscle diseases in db/db type 2 diabetic mice and provide a potential drug to prevent skeletal muscle dysfunction in T2DM patients.

Exercise training protects the heart against ischemia-reperfusion injury: A central role for mitochondria?

Ischemic heart disease is one of the main causes of morbidity and mortality worldwide. Physical exercise is an effective lifestyle intervention to reduce the risk factors for cardiovascular disease and also to improve cardiac function and survival in patients with ischemic heart disease. Among the strategies that contribute to reduce heart damages during ischemia and reperfusion, regular physical exercise is efficient both in rodent experimental models and in humans. However, the cellular and molecular mechanisms of the cardioprotective effects of exercise remain unclear. During ischemia and reperfusion, mitochondria are crucial players in cell death, but also in cell survival. Although exercise training can influence mitochondrial function, the consequences on heart sensitivity to ischemic insults remain elusive. In this review, we describe the effects of physical activity on cardiac mitochondria and their potential key role in exercise-induced cardioprotection against ischemia-reperfusion damage. Based on recent scientific data, we discuss the role of different pathways that might help to explain why mitochondria are a key target of exercise-induced cardioprotection.

Oxidative Stress Modulation by Cameroonian Spice Extracts in HepG2 Cells: Involvement of Nrf2 and Improvement of Glucose Uptake

Oxidative stress plays a relevant role in the progression of chronic conditions, including cardiometabolic diseases. Several Cameroonian plants, including spices, are traditionally used as herbal medicines for the treatment of diseases where oxidative stress contributes to insulin resistance, like type 2 diabetes mellitus. This study evaluated the antioxidant capacity and the effects on oxidative-stress-induced impairment of glucose uptake of 11 Cameroonian spice extracts. H₂O₂-induced reactive oxygen species (ROS) production by human HepG2 cells was significantly reduced by 8/11 extracts. The most effective extracts, Xylopia parviflora, Echinops giganteus, and Dichrostachys glomerata, showed a concentration-dependent ROS-scavenging activity, which involved Nrf2 translocation into the nucleus. Xylopia parviflora, Tetrapleura tetraptera, Dichrostachys glomerata, Aframomum melegueta, and Aframomum citratum extracts showed the highest antioxidant capacity, according to oxygen radical absorbance capacity (ORAC) (2.52-88 μM Trolox Eq/g of extract), ferric-reducing antioxidant power (FRAP) (40.23-233.84 mg gallic acid Eq/g of extract), and total phenol (8.96-32.96% mg gallic acid Eq/g of extract) assays. In HepG2 cells, glucose uptake was stimulated by 4/11 extracts, similarly to insulin and metformin. H₂O₂-induced oxidative stress reduced glucose uptake, which was rescued by pretreatment with Xylopia aethiopica, Xylopia parviflora, Scorodophloeus zenkeri, Monodora myristica, and Dichrostachys glomerata extracts. The ROS-scavenging ability of the spice extracts may reside in some secondary metabolites observed by phytochemical profiling (reverse-phase high-performance liquid chromatography coupled to a diode array detector (HPLC-UV-DAD)). Further studies are needed to better clarify their biological activities and potential use to control oxidative stress and promote insulin sensitivity.

Oxidative Stress in DNA Repeat Expansion Disorders: A Focus on NRF2 Signaling Involvement

DNA repeat expansion disorders are a group of neuromuscular and neurodegenerative diseases that arise from the inheritance of long tracts of nucleotide repetitions, located in the regulatory region, introns, or inside the coding sequence of a gene. Although loss of protein expression and/or the gain of function of its transcribed mRNA or translated product represent the major pathogenic effect of these pathologies, mitochondrial dysfunction and imbalance in redox homeostasis are reported as common features in these disorders, deeply affecting their severity and progression. In this review, we examine the role that the redox imbalance plays in the pathological mechanisms of DNA expansion disorders and the recent advances on antioxidant treatments, particularly focusing on the expression and the activity of the transcription factor NRF2, the main cellular regulator of the antioxidant response.