Free Radical Research最新文献

Selenomethionine (SeMet) increases glutathione peroxidase (GPx) activity, a seleno-enzyme with an antioxidant function that counteracts reactive oxygen species (ROS). After ablation, transplant organs generate ROS during irrigation-reperfusion injury. GPx1 can be downregulated during hypoxia in ablated organs. ROS can oxidize proteins, inducing proteolysis, which compromises the transplant outcome. SeMet administration to living donors can decrease proteolysis in transplant organs, improving their preservation. Accordingly, SeMet was administered to rats for 7 days. After this period, the liver, heart, and kidneys were ablated, and proteins extracted at different postmortem intervals (PMI). Total protein analysis showed a lower protein concentration decrease in kidneys and heart from SeMet-supplemented rats after a 6 hs PMI. Molecular weight changes of proteins to proteolysis products (PPs) were studied by size exclusion chromatography (SEC). SeMet decreased PPs (<29.5 kDa) in the liver, kidneys, and heart. Specific analysis of GPx1 proteolysis by affinity chromatography coupled to inductively coupled plasma mass spectrometry (AF-ICP-MS) showed that SeMet administration decreased GPx1 proteolysis 24% in the liver and 16.8% in the heart. SeMet administration reduced the proteolysis velocity of GPx1 (V_GPx1) in heart. SeMet administration to living donors for seven days decreased proteolysis in transplant organs, improving its conservation.

Catechin is a major antioxidant and also shows anti-cancer effect. We have synthesized a catechin analog possessing a planar structure, planar catechin, which has 10-fold larger radical-scavenging activity than the parental (+)-catechin, and demonstrated that the planar catechin showed a significant cytotoxicity in cancer cells. However, the planar catechin has a possibility to lose the innate activity before reaching target cells, because of the higher reactivity with other biological molecules. In this study, we introduced acetyl groups to the phenolic hydroxy groups, which are considered as active sites of the planar catechin, in order to protect from the oxidation of the planar catechin, and examined the effects on cells regarding the toxicity. The acetylated planar catechin showed a remarkable cytotoxicity compared to the original planar catechin, especially in cancer cells, whereas the superoxide scavenging activity of the acetylated planar catechin was weak. On the other hand, after the acetylated planar catechin was treated with esterase, the enhanced superoxide scavenging activity was confirmed by an electron paramagnetic resonance technique. These results indicate that the activity of the planar catechin was maintained by acetylation of the phenolic hydroxy groups and the deprotection by intracellular esterase restored the activity, leading to the induction of the severe cytotoxicity.

Thioredoxin (TRX), a redox-regulatory protein of 12 kDa, plays an essential role in modulating oxidative stress and mediating inflammatory processes. In this study, we compared and analyzed the anti-inflammatory effects of topically applied recombinant human TRX (rhTRX), hydrocortisone, and their combination on murine models of contact dermatitis (CD). Topical application of rhTRX, hydrocortisone, and their synergistic combination notably ameliorated ear edema, reduced neutrophilic infiltration within the ear tissues and suppressed the production of cytokines. We explored the distinct anti-inflammatory mechanisms of rhTRX versus hydrocortisone in phorbol-12-myristate-13-acetate (PMA)-induced PAM212 cells. These treatments collectively downregulated the phosphorylation of p-JNK and p-P38 mitogen-activated protein kinases (MAPKs) in the cells. In addition, rhTRX did not impact the proliferation of CD4+ and CD8+ T lymphocytes. Notably, rhTRX directly downregulated macrophage migration inhibitory factor (MIF), whereas it had no effects on the glucocorticoid-induced leucine zipper (GILZ). Collectively, these findings delineated that rhTRX ameliorated CD by curtailing MAPK pathway, and enhancing glucocorticoid responsiveness through the targeted downregulation of MIF. Consequently, it holds promise as a therapeutic agent for the treatment of CD and warrants further investigation in translational research.

IQOS is a heated tobacco product (HTP) claimed to be less harmful than regular cigarettes. It is unknown whether IQOS emissions contain radicals, cause DNA damage or affect the expression of DNA repair markers in human bronchial epithelial cells. This has important implications as IQOS diffusion is quickly growing, but little toxicological and genotoxic information on its emissions is available. Therefore, we determined the presence of radicals in cigarette smoke extract (CSE) and IQOS extract (IQOSE) by Electron Spin Resonance (ESR) spectroscopy and measured their levels of Tobacco-Specific Nitrosamines (TSNAs) with liquid chromatography-mass spectrometry (LC-MS). Next, DNA damage induced by CSE and IQOSE was determined by means of the Fpg-modified comet assay in human bronchial epithelial cells (BEAS-2B). Finally, the mRNA and protein levels of DNA repair markers in response to both extracts were evaluated. CSE contained significantly more reactive oxygen species (ROS) and TSNAs, whereas more carbon/nitrogen-centered radicals were detected in IQOSE. After 1 h exposure, 3%CSE and 5%IQOSE caused DNA oxidation, while 5%IQOSE also induced DNA strand breaks and alkali-labile sites. Exposure of cells to 1% and 3% IQOSE for 4 h upregulated the expression of DNA repair genes, whereas no significant impact on DNA repair protein levels was observed. This study shows that IQOS extract contains significant amounts of radicals and TSNAs, can induce DNA damage and increase the expression of DNA repair genes in human bronchial epithelial cells. Whether IQOS use is associated with higher risk of developing lung cancer remains to be determined.

Sepsis, characterized by severe systemic inflammation and an excessive immune response to infection, is frequently triggered by bacterial endotoxins like lipopolysaccharide (LPS) from Gram-negative bacteria. Moreover, sepsis-induced cardiac dysfunction remains a leading cause of mortality. This study aims to elucidate the effects of LPS-induced cardiac injury on mitochondrial damage, oxidative stress, and subsequent cardiac dysfunction. LPS injections (in rats and mice) for three days (1.5 mg/kg) impacted the body weight and increased cardiac TNF-α. Additionally, it decreased mitochondrial complexes I and II activities while complexes III and IV remained unaffected. Disturbed in mitochondrial electron transport chain leads to an increase in reactive oxygen species (ROS). Indeed, LPS treatment significantly increased mitochondrial hydrogen peroxide production, reduced the activity of antioxidant enzymes catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase activity. This was accompanied by decreased mitochondrial and cytosolic sulfhydryl proteins and parallel increased cellular lipid peroxidation in the presence or absence of Fe²⁺. LPS-treated samples had increased glutathione s-transferase activity, which may be an attempt of the cell to remove toxic lipid peroxidation products. In a more acute Langendorff-perfused rat hearts, LPS infusion (0.5 μg/mL) induced a significant elevation in left ventricular end-diastolic pressure and a decrease in left ventricular developed pressure. These findings elucidate the harmful mitochondrial and oxidative effects of LPS in cardiac tissue and could help the development of targeted therapies to mitigate the adverse effects of sepsis-induced cardiac dysfunction.

Nitroxides, which have unpaired electrons, find diverse applications owing to their characteristic redox and radical chemistries. To fine-tune the properties of nitroxide compounds for various applications, we investigated the effect of distant substituents on their reactivity. We synthesized 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl (4-oxo-TEMPO) derivatives with electron-donating or electron-withdrawing groups at the para position of the benzyl group attached to the 2-position. The reactivities of these compounds were evaluated by measuring their second-order reaction rate constants with ascorbate using ESR spectroscopy. Density functional theory (DFT) calculations for each compound revealed a correlation between the charge of the N-O moiety and the second-order reaction rate constant. Notably, even substituents positioned far from the nitroxide center significantly affected the reductive reactivity with ascorbate. These findings suggest that both proximal and distal structural modifications can be leveraged to fine-tune nitroxide properties, providing a basis for the rational design of nitroxides with tailored reactivities.

Age-related macular degeneration (AMD), a serious physical and mental health problem worldwide, is the leading cause of irreversible, severe vision impairment and loss in older people. AMD is associated with multiple risk factors, many of which are closely linked to increased oxidative stress. Some studies have suggested that long-term and excessive exposure to blue light may be a potential risk factor for the development or progression of AMD. Recently, we demonstrated that blue light irradiation caused oxidative stress in all-trans-retinal (atRAL)-exposed human ARPE-19 retinal pigment epithelium cells by generating singlet oxygen (¹O₂), leading to apoptotic cell death. Luteolin, a flavonoid found in various edible plants, has been reported to possess divergent health-promoting properties including anti-oxidative and chemopreventive effects by up-regulating anti-oxidative and phase II detoxifying enzymes through activation of Keap1/Nrf2 signaling. Herein, we verified the cytoprotective action of luteolin against blue light irradiation using atRAL-exposed ARPE-19 cells. Our results established that luteolin effectively prevented blue light-induced apoptosis of ARPE-19 cells by mitigating oxidative stress. We also confirmed that luteolin suppressed intracellular accumulation of ¹O₂ and formation of atRAL-derived lipofuscin by increased expression of heme oxygenase-1 and aldehyde dehydrogenase 1A1 through activation of Keap1/Nrf2 signaling. Furthermore, our data implied that the luteolin-provoked activation of Keap1/Nrf2 signaling might be due to covalent binding of luteolin o-quinone to the critical cysteinyl thiol in Keap1. The present results suggest that luteolin could be helpful in the prevention and amelioration of blue light-induced retinal degeneration, including AMD.

Apart from a strong association with childhood-onset asthma, orosomucoid 1-like protein 3 (ORMDL3), an endoplasmic reticulum (ER)-localized transmembrane protein, is also linked with chronic obstructive pulmonary disease (COPD), in which cigarette smoke (CS) is the crucial risk factor. Compared to healthy subjects, COPD patients had elevated ORMDL3 mRNA in well-differentiated primary human bronchial epithelial cells (HBECs). However, its role in COPD remains understudied. We, therefore, hypothesize that ORMDL3 may play an essential role in CS-induced chronic mucus hypersecretion and inflammation via activation of specific unfolded protein response (UPR) pathways under ER stress in primary HBECs. Gene silencing using siRNA for ORMDL3 was performed in submerged culture of primary HBECs before 24-h cigarette smoke medium (CSM) exposure. The mucin, inflammatory and mitochondrial markers, and the activation of the UPR pathways were evaluated. CSM triggered significant induction of ORMDL3 expression at both mRNA and protein level, which was significantly inhibited by silencing ORMDL3. In addition, ORMDL3 knockdown inhibited CSM-induced mucin MUC5AC mRNA and release of inflammatory marker interleukin (IL)-8. Silencing ORMDL3 reduced CSM-induced ER stress via inhibiting the activating transcription factor (ATF)6 and the inositol-requiring enzyme (IRE)1 of the UPR pathways. The involvement of ORMDL3 was demonstrated in mitochondrial dynamics via fusion protein Mfn2 and mitochondrial respiration after CSM stimulation. In conclusion, ORMDL3 is an inducible gene in mediating CS-induced activation of specific ATF6 and IRE1 pathways to regulate mucus hypersecretion and inflammation. Therefore, ORMDL3 may be a promising therapeutic target to treat smoking-associated mucus hypersecretion and inflammation in COPD.

The biological effects of edaravone (Eda), a free radical scavenger, include anti-inflammatory, antioxidant, and neuroprotective qualities. Nevertheless, the function and potential mechanisms of Eda in central nervous system injury damage are still unknown. A rat model of acute diquat toxicity was constructed to observe the pathological changes in brain tissues after diquat administration. The changes of mitophagy and ferroptosis in PC12 cells were assessed to the protective activity of Eda. To assess the methylation levels of m6A RNA, the EpiQuik m6A RNA Methylation Quantification Kit was utilized. RIP, dual luciferase reporter assay and mRNA stability detection confirm the relationship between METTL14 and Aldh11l1. Knockdown and overexpression experiments were performed to determine the effects of METTL14 and Aldh1l1 on rats and PC12 cells stimulated with diquat under Eda treatment. Eda dramatically ameliorated diquat-induced central nervous system injury. Eda notably attenuated apoptosis, pro-inflammatory cytokines activation, and oxidative stress damage in diquat-induced rats. Eda significantly suppressed apoptosis, mitophagy and ferroptosis after diquat-stimulated PC12 cells. Mitophagy inhibitor Mdivi-1 reversed the induction of ferroptosis effects of diquat via decreased Fe2+ content and increased Ca2+ level. knockdown of METTL14 reversed the therapeutic effect of Eda on diquat-induced injury. Eda promoted METTL14-mediated Aldh1l1 m6A methylation and alleviates acute central nervous system injury induced by diquat in vivo and in vitro. Eda has a protective effect on diquat-induced nervous system injury, and its mechanism may be related to the activation of m6A modification of Aldh11l1 by METTL14 and the inhibition of mitophagy and.

ferroptosis.

The purpose of this study is to investigate FABP3's biological function and potential mechanism in cataract. Treatment of H₂O₂ raised FABP3 expression. H₂O₂ decreased cell viability, enhanced apoptosis, promoted Bax and cleaved caspase-3 expression, inhibited Bcl-2 expression, enhanced the levels of IL-6, IL-1β, and TNF-α, raised MDA level, and decreased SOD and GSH levels in HLE-B3 cells. However, the effects of H₂O₂ on cell viability, apoptosis, inflammatory cytokines, and oxidative stress were reversed by FABP3 knockdown and aggravated by FABP3 overexpression. H₂O₂ increased the levels of lipid hydroperoxides and Fe²⁺, but reduced the expression of GPX4, SLC7A11, and Ferritin protein. Nevertheless, knockdown of FABP3 reversed the changes of lipid hydroperoxides, Fe²⁺, GPX4, SLC7A11, and Ferritin protein, and FABP3 overexpression caused the opposite results. In addition, the inhibition of FABP3 knockdown on cell apoptosis, inflammation, and oxidative stress was reversed by ferroptosis inducer (erastin), and the promotion of FABP3 overexpression on cell apoptosis, inflammation, and oxidative stress was reversed by ferroptosis inhibitor (Fer-1). Taken together, knockdown of FABP3 in lens epithelial cells treated with H₂O₂ restrained apoptosis, inflammation, and oxidative stress through regulating ferroptosis, suggesting that FABP3 might be a potential target for cataract treatment.