Free Radical Research最新文献

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra. Recently, disorders in metabolism of metals, including copper (Cu) and iron (Fe), have been reported to be linked to the pathogenesis of PD. We previously demonstrated that 6-hydoroxydopamine (6-OHDA), a neurotoxin used for the production of PD model animals, decreases Atox1, a Cu chaperone, and ATP7A, a Cu transporter, and disrupts intracellular Cu metabolism in human neuroblastoma SH-SY5Y cells. However, the exact mechanisms remain unclear. Meanwhile, intracellular Fe modulates 6-OHDA-induced cellular responses. In this study, we investigated whether Fe participates in 6-OHDA-induced abnormality in Cu metabolism. 6-OHDA-induced reactive oxygen species (ROS) production and cellular injury were suppressed by Fe chelators, deferoxamine and 2,2'-bipyridyl (BIP). These chelators also restored 6-OHDA-induced degradation of Atox1 and ATP7A proteins and subsequent Cu accumulation, indicating that intracellular Fe is involved in the disruption of Cu homeostasis associated with 6-OHDA. Atox1 has redox-sensitive cysteine (Cys) residues in its Cu-binding site. The Cys residues of Atox1 were oxidized by 6-OHDA, and BIP suppressed their oxidation. Moreover, the replacement of Cys with histidine in the Cu-binding site conferred resistance to 6-OHDA-induced Atox1 degradation. These results suggest that oxidized modification of Atox1 by 6-OHDA is likely to accelerate its degradation. Thus, we conclude that Fe and Cu metabolisms are closely related to each other in the pathogenesis of PD.

Iron oxide (Fe-O) has anti-tumor properties, due to its ability of catalyzing hydrogen peroxide (H₂O₂) of tumor cells to generate reactive oxygen species (ROS) and then cause ferroptosis. Its anti-tumor performance is restricted due to insufficient H₂O₂ in tumor cells. A nanomedicine, Au nanoparticles (NPs) grown on Fe-O, was integrated into poly-l-lactide (PLLA) scaffolds. Results indicated that Au NPs could consume glucose of tumor cells to produce H₂O₂, which supplemented reaction substrate. PLLA/Au@Fe-O scaffold showed enhanced anti-tumor activities against MG63, including increased mortality, decreased migration and colony formation. PLLA/Au@Fe-O scaffold promoted ferroptosis in MG63, including up-regulation of COX-2 protein, down-regulation of FTH1 protein and GPX4 protein. PLLA/Au@Fe-O scaffold also promoted autophagy in MG63, including down-regulation of P62 protein, and up-regulation of LC3BII/I. Mechanistically, PLLA/Au@Fe-O scaffold possessed enhanced anti-tumor activities through promoting ferroptosis and autophagy.

Both mothers and infants experience oxidative stress due to gestational diabetes mellitus (GDM), which is strongly associated with adverse pregnancy outcomes. Ferroptosis, a novel form of programmed cell death characterized by iron-dependent lipid peroxidation, is believed to play a critical role in the pathogenesis and progression of GDM. Metformin (MET) has shown potential in alleviating oxidative stress; however, research on its specific mechanisms of action in GDM remains limited. We collected placental tissues from GDM patients and healthy controls and established an in vitro GDM cell model. We measured markers of ferroptosis including malondialdehyde (MDA), glutathione (GSH), and glutathione peroxidase 4 (GPX4) activity. Additionally, we evaluated reactive oxygen species (ROS) levels, apoptosis, cell viability, and migration in the cell model. Our findings revealed significant changes in the GDM group compared to controls, including increased MDA and GSSG levels, decreased GSH levels, and reduced expression of GPX4 protein in the GDM placenta. High-glucose (HG) conditions were shown to reduce trophoblast cell viability and migration, accompanied by elevated ROS and MDA levels, as well as reduced expression of GSH, GPX4, Nrf2, and HO-1 proteins. Importantly, treatment with MET reversed these effects, similar to the action of deferoxamine mesylate (DFOM), a known ferroptosis inhibitor. These results confirm the occurrence of ferroptosis in the placentas of GDM patients and demonstrate that MET mitigates high-glucose-induced ferroptosis in trophoblasts through the Nrf2/HO-1 signaling pathway. This study provides novel insights into the protective mechanisms of MET, offering potential therapeutic strategies for GDM. management.

The concept of dual-state hyper-energy metabolism characterized by elevated glycolysis and OxPhos has gained considerable attention during tumor growth and metastasis in different malignancies. However, it is largely unknown how such metabolic phenotypes influence the radiation response in aggressive cancers. Therefore, the present study aimed to investigate the impact of hyper-energy metabolism (increased glycolysis and OxPhos) on the radiation response of a human glioma cell line. Modulation of the mitochondrial electron transport chain was carried out using a 2,4-dinitrophenol (DNP). Metabolic characterization was carried out by assessing glucose uptake, lactate production, mitochondrial mass, membrane potential, and ATP production. The radiation response was examined by cell growth, clonogenic survival, and cell death assays. Macromolecular oxidation was assessed by DNA damage, lipid peroxidation, and protein carbonylation assay. Hypermetabolic OPM-BMG cells exhibited a significant increase in glycolysis and OxPhos following irradiation as compared to the parental BMG-1 cells. Enhanced radioresistance of OPM-BMG cells was evidenced by the increase in α/β ratio (9.58) and D1 dose (4.18 Gy) as compared to 4.36 and 2.19 Gy in BMG-1 cells respectively. Moreover, OPM-BMG cells were found to exhibit increased resistance against radiation-induced cell death, and macromolecular oxidation as compared to BMG-1 cells. Inhibition of glycolysis and mitochondrial complex-II significantly enhanced the radiosensitivity of OPM-BMG cells compared to BMG-1 cells. Our results demonstrate that the hyper-energy metabolism of increased glycolysis and OxPhos confer radioresistance. Consequently targeting glycolysis and OxPhos in combination with radiation may overcome therapeutic resistance in aggressive cancers like glioma.

Diamine oxidase (DAO) histamine-degradation rates are compromised in plasma of mastocytosis patients during severe mast cell activation events. Mast cell-liberated histamine induces the release of nitric oxide (NO) close to DAO extracellular storage sites. We hypothesized that NO inhibits DAO activity. Recombinant human DAO activity was measured after incubation with NO-releasing NONOates (R¹R²N-(NO^-)-N = O). Topaquinone reactivity was quantified by absorption measurements and by mass spectrometry. Several murine models of NO-production were assessed for DAO activity inhibition in vivo. Nitric oxide released from NONOates dose dependently and irreversibly inhibited DAO activity. The NO scavengers Trolox (Vitamin E derivative) and 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (C-PTIO), the reversible DAO inhibitors diminazene and ciproxifan, the substrates histamine (EC₅₀ = 32 µM) and putrescine (EC₅₀ = 39 µM), heparin whole blood and plasma protected DAO from inhibition. Nitric oxide reduced the reactivity of topaquinone to phenylhydrazine by 90%. None of the NO producing in vivo models showed DAO inhibition in plasma or tissue. Nitric oxide is a potent irreversible DAO inhibitor in vitro representing the first discovered natural inhibitor for this enzyme. Endogenous mouse DAO inhibition in vivo could not be demonstrated. The true nature of human DAO activity inhibition during severe mastocytosis events remains unknown.

The synthetic naringenin derivative (2S)-8-carboxymethylnaringenin (CMN) was developed for the treatment of bacterial and viral respiratory infections. There are indications that CMN may act as an antioxidant, however, no studies have been conducted in this regard. This work is aimed at assessing the antiradical capacity of CMN against various physiologically relevant species in physiological environments by using thermodynamic and kinetic calculations. According to the results, CMN only exhibits modest HOO^• antiradical activity in lipid medium, modeled here as pentyl ethanoate solvent, with an overall rate constant (k_overall) of 2.01 × 10² M^-1 s^-1. However, significant antiradical activity is predicted for the aqueous medium (k_overall = 2.60 × 10⁵ M^-1s^-1) that is equivalent to the activity of the reference antioxidant Trolox. In a screen performed on a range of radicals, HO^•, NO₂, SO₄^•-, N₃^•, CH₃O^•, CCl₃O^•, CH₃OO^•, and CCl₃OO^• were also successfully scavenged by CMN in water at physiological pH. Therefore, other than a potent drug, CMN is also a good antioxidant in polar environments.

Ferroptosis characterized by iron-dependent lipid peroxidation induced by traumatic brain injury (TBI) is an important factor that aggravates diseases. Studies have shown that tetrahydrocurcumin (THC) has neuroprotective effects in brain injury. However, whether THC inhibits neurocyte ferroptosis after TBI and its mechanism remains unclear. To investigate this, a weight-drop model in rats and H₂O₂ induced oxidative stress model in SH-SY5Y cells were established, and THC was used for treatment. Immunohistochemical staining showed that iron deposition reached its peak at 8th day after TBI. We found that THC remarkably inhibited iron accumulation in the cortical cortex and corpus callosum, improved neurological damage, reduced acute cerebral edema, weight loss, oxidative stress, and inflammation. Furthermore, the activity of iPLA2β was significantly reduced, and phosphorylation of p38 was increased after TBI, while THC alleviated the decrease in iPLA2β activity and increase in the level of P-p38. It confirmed that THC effectively mitigated ferroptosis, while iPLA2β inhibitor s-BEL could reverse the effects of THC on ferroptosis in vivo and in vitro experiments. In addition, SB202190 which is an inhibitor of p38 could enhance THC protection and lessen formation of ferroptosis-related proteins in cells. In conclusion, these findings suggested that THC may promote neurological function recovery after TBI by inhibiting neuron ferroptosis via activity of iPLA2β/P-p38.

Little is known regarding the effects high-intensity training performed in hypoxia on the oxidative stress and antioxidant systems. The aim of this study was to assess the potential effect of 4 weeks of repeated sprint training in hypoxia (RSH) on the redox balance. Forty male well-trained cyclists were matched into two different interventions (RSH, n = 20) or in normoxia, RSN, n = 20) and tested twice (before (Pre-) and after (Post-) a 4-week of training) for performance (repeated sprint ability (RSA) test), oxidative stress, and antioxidant status. Antioxidant enzyme activity (Superoxide Dismutase, Glutathione Peroxidase, and catalase), NO metabolites (NOx: nitrites and nitrates), ferric reducing antioxidant power, Malondialdehyde (MDA), nitrotyrosine, and carbonyls were measured in plasma. At Post-, MDA, and carbonyls increased (p < 0.05) in the RSN group both at rest (+90.6%) and also acutely in response to RSA (+22.9%); but not in RSH. At Post-, in the RSH group, catalase increased (p < 0.05) both at rest (+44.7%) and in response to the RSA test (+66.3%). At Post-, SOD, and nitrotyrosine decreased after RSA and at rest, regardless of the group (p = 0.0012 and p = 0.0413, respectively). At Post-, NOx decreased after the RSA test, regardless of the group (p < 0.05). In conclusion, several weeks of RSH training limits the increase in oxidative stress markers both at rest and in response to RSA test. Moreover, such training downregulated SOD activity, possibly due to an overproduction of reactive oxygen species. These findings could constitute a paradigm shift with a better enzymatic adaptation after RSH concomitant with a distinct reactive oxygen species (ROS) production between RSH and RSN.

Patients with hypoxemia require high-concentration oxygen therapy. However, prolonged exposure to oxygen concentrations 21% higher than physiological concentrations (hyperoxia) may cause oxidative cellular damage. Pulmonary alveolar epithelial cells are major targets for hyperoxia-induced oxidative stress. In this study, we evaluated the therapeutic potential of the antioxidant N-acetyl-L-cysteine (NAC) for preventing hyperoxia-induced cell death. In vitro experiments were performed using the human lung cancer cell line A549. In brief, NAC-treated and untreated cells were exposed to various concentrations of oxygen (hyperoxia) for different durations. The results indicated that hyperoxia inhibited proliferation and caused cell cycle arrest in A549 cells. It also induced necrosis and autophagy. Furthermore, hyperoxia increased intracellular reactive oxygen species levels and altered mitochondrial membrane potential. Co-treatment with NAC improved the survival of cells exposed to 95% oxygen for 24 h. Experiments performed using a neonatal rat model of acute lung injury confirmed that hyperoxia induced an autophagic response. This study provides evidence for hyperoxia-induced autophagy both in vitro and in vivo. NAC can protect A549 cells from death induced by short-term hyperoxia. Our findings may inform protective strategies against hyperoxia-induced injury in developing lungs-for example, bronchopulmonary dysplasia in premature infants.

Free radicals have been implicated in the pathogenesis of cancer along with cardiovascular, neurodegenerative, pulmonary and inflammatory disorders. Further, the relationship between oxidative stress and disease is distinctively established. Clinical trials using anti-oxidants for the prevention of disease progression have indicated some beneficial effects. However, these trials failed to establish anti-oxidants as therapeutic agents due to lack of efficacy. This is attributed to the fact that living systems are under dynamic redox control wherein their redox behavior is compartmentalized and simple aggregation of redox couples, distributed throughout the system, is of miniscule importance while determining their overall redox state. Further, free radical metabolism is intriguingly complex as they play plural roles segregated in a spatio-temporal manner. Depending on quality, quantity and site of generation, free radicals exhibit beneficial or harmful effects. Use of nonspecific, non-targeted, general ROS scavengers lead to systemic elimination of all types of ROS and interferes in cellular signaling. Failure of anti-oxidants to act as therapeutic agents lies in this oversimplification of extremely dynamic cellular redox environment as a static and non-compartmentalized redox state. Rather than generalizing the term "oxidative stress" if we can identify the "type of oxidative stress" in different types of diseases, a targeted and more specific anti-oxidant therapy may be developed. In this review, we discuss the concept of redox dynamics, role and type of oxidative stress in disease conditions, and current status of anti-oxidants as therapeutic agents. Further, we probe the possibility of developing novel, targeted and efficacious anti-oxidants with drug-like properties.