Search Results (60)

Gaseous chlorine dioxide (ClO₂) is a potent antimicrobial agent used to control microbial contamination in food and water. This study evaluates the bactericidal activity of gaseous ClO₂ released from a sodium chlorite (NaClO₂) pad against Campylobacter jejuni. Exposure to a low concentration (0.4 mg/L) of dissolved ClO₂ for 2 h resulted in a >93% reduction of C. jejuni, highlighting the bacterium’s extreme sensitivity to gaseous ClO₂. To elucidate the molecular mechanism of ClO₂-induced bactericidal action, transcriptomic analysis was conducted using RNA sequencing (RNA-seq). The results indicate that C. jejuni responds to ClO₂-induced oxidative stress by upregulating genes involved in reactive oxygen species (ROS) detoxification (sodB, ahpC, katA, msrP, and trxB), iron transport (ceuBCD, cfbpABC, and chuBCD), phosphate transport (pstSCAB), and DNA repair (rdgB and mutY). Reverse transcription-quantitative PCR (RT-qPCR) validated the increased expression of oxidative stress response genes but not general stress response genes (spoT, dnaK, and groES). These findings provide insights into the antimicrobial mechanism of ClO₂, demonstrating that oxidative damage to essential cellular components results in bacterial cell death. Full article

Cataracts, the leading cause of blindness globally, are caused by oxidative stress and inflammation, which disrupt lens transparency due to increased accumulation of reactive oxygen species (ROS) as well as protein and DNA damage during aging. Using in vitro, ex vivo, and in vivo models, we determined the protective efficacy of N-acetylcysteine amide (NACA) against oxidative stress-induced and aging-induced cataractogenesis. We found that lens epithelial cells exposed to the oxidative stress inducers hydrogen peroxide (H₂O₂) or tert-butyl hydroperoxide showed significant ROS accumulation and reduced cellular viability. These effects were inhibited by NACA via the suppression of ROS and thioredoxin-interacting protein (Txnip) expression, a regulator of oxidative stress-related cellular damage and inflammation. In ex vivo lens experiments, NACA significantly reduced H₂O₂-induced lens opacity and preserved lens integrity. Similarly to NACA-treated lenses ex vivo, the integrity and opacity of aged mouse lenses, when topically instilled with NACA, were preserved and reduced, respectively, and are directly related to reduced Txnip and increased thioredoxin (Trx) expression levels. Overall, our findings demonstrated the protective ability of NACA to abate aberrant redox-active pathways, particularly the ROS/TRX/TXNIP axis, thereby preventing cataractogenesis and preserving eye lens integrity and ultimately impeding aging-related cataracts. Full article

Thioredoxin-1 (Trx-1) is an important redox protein found in almost all prokaryotic and eukaryotic cells, which has a highly conserved active site sequence: Trp-Cys-Gly-Pro-Cys. To investigate whether the Trp31 residue is essential for the antioxidant activity of human Trx-1 (hTrx-1), we mutated Trx-1 by replacing Trp31 with Ala31 (31Ala) or deleting Trp31 residue (31Del). We introduced 31Ala and 31Del mutations into prokaryotic cells for hTrx-1 protein expression, protein purification and evaluation of antioxidant activity. The results showed that neither the replacing mutation to Ala31 nor the deletion of Trp31 residue affected the efficient expression of hTrx-1 protein in prokaryotic cells, indicating that neither form of Trp31 mutation would disrupt the folded structure of the Trx-1 protein. Comparison of the antioxidant activity of purified hTrx-1 proteins of wild-type, 31Ala and 31Del forms revealed that both mutant forms significantly decreased the antioxidant capacity of hTrx-1. Further investigations on eukaryotic cells showed that H₂O₂ treatment caused massive cell death in EA.Hy926 human endothelial cells with 31Ala and 31Del mutations compared to wild-type cells, which was associated with increased ROS production and downregulation of antioxidant Nrf2 and HO-1 expression in the mutant cells. These results suggested that mutations in the Trp31 residue of hTrx-1 remarkably disrupted cellular redox defense against oxidative stress. The antioxidant activity of hTrx-1 relies on the thiol–disulfide exchange reaction, in which the content of thiol groups forming disulfide bonds in hTrx-1 is critical. We found that the content of free thiol groups specifically participating in disulfide bond formation was significantly lower in Trp31 mutant hTrx-1 than in wild-type hTrx-1; that was speculated to affect the formation of disulfide bonds between Cys32 and Cys35 by virtual analysis, thus abolishing the antioxidant activity of hTrx-1 in cleaving oxidized groups and defending against oxidative stress. The present study provided valuable insights towards understanding the importance of Trp31 residue of hTrx-1 in maintaining the correct conformation of the Trx fold structure, the antioxidant functionality of hTrx-1 and the cellular redox defense capability against oxidative stress. Full article

Hydrogen peroxide (H₂O₂) plays a crucial role in cell signaling in response to physiological and environmental perturbations. H₂O₂ can oxidize typical 2-Cys peroxiredoxin (PRX) first into a sulfenic acid, which resolves into a disulfide that can be reduced by thioredoxin (TRX)/TRX reductase (TR). At high levels, H₂O₂ can also hyperoxidize sulfenylated PRX into a sulfinic acid that can be reduced by sulfiredoxin (SRX). Therefore, PRX, TRX, TR, and SRX (abbreviated as PTRS system here) constitute the coupled sulfenylation and sulfinylation cycle (CSSC), where certain oxidized PRX and TRX forms also function as redox signaling intermediates. Earlier studies have revealed that the PTRS system is capable of rich signaling dynamics, including linearity, ultrasensitivity/switch-like response, nonmonotonicity, circadian oscillation, and possibly, bistability. However, the origins of ultrasensitivity, which is fundamentally required for redox signal amplification, have not been adequately characterized, and their roles in enabling complex nonlinear dynamics of the PTRS system remain to be determined. Through in-depth mathematical modeling analyses, here we revealed multiple sources of ultrasensitivity that are intrinsic to the CSSC, including zero-order kinetic cycles, multistep H₂O₂ signaling, and a mechanism arising from diminished H₂O₂ removal at high PRX hyperoxidation state. The CSSC, structurally a positive feedback loop, is capable of bistability under certain parameter conditions, which requires embedding multiple sources of ultrasensitivity identified. Forming a negative feedback loop with cytosolic SRX as previously observed in energetically active cells, the mitochondrial PTRS system (where PRX3 is expressed) can produce sustained circadian oscillations through supercritical Hopf bifurcations. In conclusion, our study provided novel quantitative insights into the dynamical complexity of the PTRS system and improved appreciation of intracellular redox signaling. Full article

Background/Objectives: Infective endocarditis (IE) most commonly results from infections by Gram-positive bacteria, and, in this condition, the redox homeostasis is lost due to the overproduction of H₂O₂, leading to the overstimulation of the immune system and the upregulation of the production of proinflammatory cytokines. The aim of this study was to evaluate the levels of oxidative biomarkers and the enzymatic and non-enzymatic antioxidant systems in subjects with IE. Methods: The study included three cases with IE that had undergone aortic valve replacement (AVR) surgery that was complicated by IE, comparing them with subjects with AVR without IE. We determined the malondialdehyde (MDA), total antioxidant capacity (TAC), carbonyl group concentration, glutathione (GSH), thiols and the nitrate/nitrite ratio (NO₃⁻/NO₂⁻) in homogenized tissue from the cardiac valves. We also measured the activity of glutathione-S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR) and thioredoxin reductase (TrxR). The superoxide dismutase (SOD) isoforms and peroxidase activity were determined using native gels. Results: There were increases in the activity of antioxidant enzymes such as GST, SOD isoforms and peroxidases (p ≤ 0.01) and decreases in oxidative stress markers such as GSH (p = 0.05); meanwhile, MDA and carbonylation were increased (p ≤ 0.05). Conclusions: The results suggest that bacterial infections favor oxidative stress in the aortic valves, which increases the SOD isoforms and peroxidase activity. This contributes to the loss of the intricate redox homeostasis system in patients with IE, causing a positive feedback loop in the oxidative background that results in damage to the heart, likely leading to a fatal outcome. Full article

Cells constantly face the challenge of managing oxidants. In aerobic organisms, oxygen (O₂) is used for energy production, generating reactive oxygen species (ROS) as byproducts of enzymatic reactions. To protect against oxidative damage, cells possess an intricate system of redox scavengers and antioxidant enzymes, collectively forming the antioxidant defense system. This system maintains the redox equilibrium and enables the generation of localized oxidative signals that regulate essential cellular functions. One key component of this defense is the thioredoxin (Trx) system, which includes Trx, thioredoxin reductase (TrxR), and NADPH. The Trx system reverses oxidation of macromolecules and indirectly neutralizes ROS via peroxiredoxin (Prx). This dual function protects cells from damage accumulation and supports physiological cell signaling. However, the Trx system also shields tumors from oxidative damage, aiding their survival. Due to elevated ROS levels from their metabolism, tumors often rely on the Trx system. In addition, the Trx system regulates critical pathways such as proliferation and neoangiogenesis, which tumors exploit to enhance growth and optimize nutrient and oxygen supply. Consequently, the Trx system is a potential target for cancer therapy. The challenge lies in selectively targeting malignant cells without disrupting the redox equilibrium in healthy cells. The aim of this review article is threefold: first, to elucidate the function of the Trx system; second, to discuss the Trx system as a potential target for cancer therapies; and third, to present the possibilities for inhibiting key components of the Trx system, along with an overview of the latest clinical studies on these inhibitors. Full article

Extreme acidophilic bacteria like Leptospirillum sp. require an efficient enzyme system to counteract strong oxygen stress conditions in their natural habitat. The genome of Leptospirillum sp. CF-1 encodes the thioredoxin-fold protein TFP2, which exhibits a high structural similarity to the thioredoxin domain of E. coli CnoX. CnoX from Escherichia coli is a chaperedoxin that protects protein substrates from oxidative stress conditions using its holdase function and a subsequent transfer to foldase chaperones for refolding. Recombinantly produced and purified Leptospirillum sp. TFP2 possesses both thioredoxin and chaperone holdase activities in vitro. It can be reduced by thioredoxin reductase (TrxR). The tfp2 gene co-locates with genes for the chaperone foldase GroES/EL on the chromosome. The “tfp2 cluster” (ctpA-groES-groEL-hyp-tfp2-recN) was found between 1.9 and 8.8-fold transcriptionally up-regulated in response to 1 mM hydrogen peroxide (H₂O₂). Leptospirillum sp. tfp2 heterologously expressed in E. coli wild type and cnoX mutant strains lead to an increased tolerance of these E. coli strains to H₂O₂ and significantly reduced intracellular protein aggregates. Finally, a proteomic analysis of protein aggregates produced in E. coli upon exposition to oxidative stress with 4 mM H₂O₂, showed that Leptospirillum sp. tfp2 expression caused a significant decrease in the aggregation of 124 proteins belonging to fifteen different metabolic categories. These included several known substrates of DnaK and GroEL/ES. These findings demonstrate that Leptospirillum sp. TFP2 is a chaperedoxin-like protein, acting as a key player in the control of cellular proteostasis under highly oxidative conditions that prevail in extreme acidic environments. Full article

Salmonella enterica serovar Gallinarum biovar Gallinarum (SG) causes fowl typhoid, a notifiable infectious disease in poultry. However, the pathogenic mechanism of SG-induced systemic infection in chickens remains unclear. Thioredoxin reductase (TrxB) is a redox protein crucial for regulating various enzyme activities in Salmonella serovar, but the role in SG-induced chicken systemic infection has yet to be determined. Here, we constructed a mutant SG strain lacking the trxB gene (trxB::Cm) and used chicken embryo inoculation and chicken oral infection to investigate the role of trxB gene in the pathogenicity of SG. Our results showed that trxB::Cm exhibited no apparent differences in colony morphology and growth conditions but exhibited reduced tolerance to H₂O₂ and increased resistance to bile acids. In the chicken embryo inoculation model, there was no significant difference in the pathogenicity of trxB::Cm and wild-type (WT) strains. In the chicken oral infection, the WT-infected group exhibited typical clinical symptoms of fowl typhoid, with complete mortality between days 6 and 9 post infection. In contrast, the trxB::Cm group showed a 100% survival rate, with no apparent clinical symptoms or pathological changes observed. The viable bacterial counts in the liver and spleen of the trxB::Cm-infected group were significantly reduced, accompanied by decreased expression of cytokines and chemokines (IL-1β, IL-6, IL-12, CXCLi1, TNF-α, and IFN-γ), which were significantly lower than those in the WT group. These results show that the pathogenicity of the trxB-deficient strain was significantly attenuated, indicating that the trxB gene is a crucial virulence factor in SG-induced systemic infection in chickens, suggesting that trxB may become a potentially effective target for controlling and preventing SG infection in chickens. Full article

This study aimed to assess the influence of varying dietary levels of astaxanthin (AST) on the growth, antioxidant capacity and lipid metabolism of juvenile swimming crabs. Six diets were formulated to contain different AST levels, and the analyzed concentration of AST in experimental diets were 0, 24.2, 45.8, 72.4, 94.2 and 195.0 mg kg⁻¹, respectively. Juvenile swimming crabs (initial weight 8.20 ± 0.01 g) were fed these experimental diets for 56 days. The findings indicated that the color of the live crab shells and the cooked crab shells gradually became red with the increase of dietary AST levels. Dietary 24.2 mg kg⁻¹ astaxanthin significantly improved the growth performance of swimming crab. the lowest activities of glutathione (GSH), total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and peroxidase (POD) were found in crabs fed without AST supplementation diet. Crabs fed diet without AST supplementation showed lower lipid content and the activity of fatty acid synthetase (FAS) in hepatopancreas than those fed diets with AST supplementation, however, lipid content in muscle and the activity of carnitine palmitoyl transferase (CPT) in hepatopancreas were not significantly affected by dietary AST levels. And it can be found in oil red O staining that dietary 24.2 and 45.8 mg kg⁻¹ astaxanthin significantly promoted the lipid accumulation of hepatopancreas. Crabs fed diet with 195.0 mg kg⁻¹ AST exhibited lower expression of ampk, foxo, pi3k, akt and nadph in hepatopancreas than those fed the other diets, however, the expression of genes related to antioxidant such as cMn-sod, gsh-px, cat, trx and gst in hepatopancreas significantly down-regulated with the increase of dietary AST levels. In conclusion, dietary 24.2 and 45.8 mg kg⁻¹ astaxanthin significantly promoted the lipid accumulation of hepatopancreas and im-proved the antioxidant and immune capacity of hemolymph. Full article

As a potent detection method for cancer biomarkers in physiological fluid, a colorimetric and electrochemical dual-mode sensing platform for breast cancer biomarker thioredoxin 1 (TRX1) was developed based on the excellent peroxidase-mimicking and electrocatalytic property of Prussian blue nanoparticles (PBNPs). PBNPs were hydrothermally synthesized using K₃[Fe(CN)₆] as a precursor and polyvinylpyrrolidone (PVP) as a capping agent. The synthesized spherical PBNPs showed a significant peroxidase-like activity, having approximately 20 and 60% lower K_m values for 3,3′,5,5′-tetramethylbenzidine (TMB) and H₂O₂, respectively, compared to those of horseradish peroxidase (HRP). The PBNPs also enhanced the electron transfer on the electrode surface. Based on the beneficial features, PBNPs were used to detect target TRX1 via sandwich-type immunoassay procedures. Using the strategies, TRX1 was selectively and sensitively detected, yielding limit of detection (LOD) values as low as 9.0 and 6.5 ng mL⁻¹ via colorimetric and electrochemical approaches, respectively, with a linear range of 10–50 ng mL⁻¹ in both strategies. The PBNP-based TRX1 immunoassays also exhibited a high degree of precision when applied to real human serum samples, demonstrating significant potentials to replace conventional HRP-based immunoassay systems into rapid, robust, reliable, and convenient dual-mode assay systems which can be widely utilized for the identification of important target molecules including cancer biomarkers. Full article

Cadmium (Cd)-induced oxidative stress detrimentally affects hyperaccumulator growth, thereby diminishing the efficacy of phytoremediation technology aimed at Cd pollution abatement. In the domain of plant antioxidant mechanisms, the role of glutathione peroxidase (GPX) in conferring Cd tolerance to tobacco (Nicotiana tabacum) remained unclear. Our investigation employed genome-wide analysis to identify 14 NtGPX genes in tobacco, revealing their organization into seven subgroups characterized by analogous conserved domain patterns. Notably, qPCR analysis highlighted NtGPX8a as markedly responsive to Cd²⁺ stress. Subsequent exploration through yeast two-hybridization unveiled NtGPX8a’s utilization of thioredoxins AtTrxZ and AtTrxm2 as electron donors, and without interaction with AtTrx5. Introduction of NtGPX8a into Escherichia coli significantly ameliorated Cd-induced adverse effects on bacterial growth. Transgenic tobacco overexpressing NtGPX8a demonstrated significantly augmented activities of GPX, SOD, POD, and CAT under Cd²⁺ stress compared to the wild type (WT). Conversely, these transgenic plants exhibited markedly reduced levels of MDA, H₂O₂, and proline. Intriguingly, the expression of NtGPX8a in both E. coli and transgenic tobacco led to increased Cd accumulation, confirming its dual role in enhancing Cd tolerance and accumulation. Consequently, NtGPX8a emerges as a promising candidate gene for engineering transgenic hyperaccumulators endowed with robust tolerance for Cd-contaminated phytoremediation. Full article

UVA radiation leads to oxidative stress and inflammation in skin cells. Therefore, the aim of this study was to compare the effect of lipid extracts from microalgae Nannochloropsis oceanica (N.o.) (marine) and Chlorococcum amblystomatis (C.a.) (freshwater) on the redox balance and PUFA metabolism in human skin fibroblasts modified by UVA. Lipid extracts from both types of microalgae introduced into the fibroblast medium after UVA irradiation significantly reduced the level of ROS and enhanced expression of Nrf2, which increased the activity/level of antioxidants (SOD1/2, CAT, GSH, Trx). The reduction in oxidative stress was accompanied by a decrease in the level of 4-HNE, its protein adducts and protein carbonyl groups. Microalgae also reduced the activity of COX1/2, FAAH and MAGL increased by UVA, and as a consequence, the level of lipid mediators (especially after N.o.) decreased, both from the group of endocannabinoids (AEA, 2-AG, PEA) and eicosanoids (PGE2, 15d-PGJ2, TXB2, 15-HETE), acting mainly through receptors related to G protein, the expression of which increases after UVA. This further contributed to the reduction in oxidative stress and pro-inflammatory signaling at NF-κB and TNFα levels. Therefore, it is suggested that lipid extracts from both N.o. and C.a. microalgae can be used to regenerate fibroblast metabolism disturbed by UVA radiation. Full article

Drought stress profoundly affects plant growth and development, posing a significant challenge that is extensively researched in the field. Thioredoxins (TRXs), small proteins central to redox processes, are crucial to managing both abiotic and biotic stresses. In this research, the VyTRXy gene, cloned from wild Yanshan grapes, was validated as a functional TRX through enzyme activity assays. VyTRXy was found to bolster photosynthesis, augment levels of osmotic regulators, stimulate antioxidant enzyme activities, and strengthen drought resilience in transgenic plants. These enhancements were evidenced by higher survival rates, optimized photosynthetic metrics, increased proline levels, augmented chlorophyll concentration, reduced electrolyte leakage, and decreased malondialdehyde and hydrogen peroxide (H₂O₂) levels. Furthermore, there was a surge in the activities of enzymes such as catalase, ascorbate peroxidase, glutathione peroxidase, dehydroascorbate reductase, and glutathione reductase, along with an increased expression of TRX peroxidase. Notably, under drought stress, there was a marked elevation in the expression of stress-responsive genes, including the adversity stress-inducible expression gene (NtRD29A) and DRE-binding protein (NtDREB), in transgenic tobacco. This investigation is pivotal in the quest for drought-resistant grapevine varieties and provides significant insights into the molecular functionality of VyTRXy in enhancing grapevine drought tolerance. Full article

Selenium (Se) is a metalloid that is recognized as one of the vital trace elements in our body and plays multiple biological roles, largely mediated by proteins containing selenium—selenoproteins. Selenoproteins mainly have oxidoreductase functions but are also involved in many different molecular signaling pathways, physiological roles, and complex pathogenic processes (including, for example, teratogenesis, neurodegenerative, immuno-inflammatory, and obesity development). All of the selenoproteins contain one selenocysteine (Sec) residue, with only one notable exception, the selenoprotein P (SELENOP), which has 10 Sec residues. Although these mechanisms have been studied intensely and in detail, the characteristics and functions of many selenoproteins remain unknown. This review is dedicated to the recent data describing the identity and the functions of several selenoproteins that are less known than glutathione peroxidases (Gpxs), iodothyronine deiodinases (DIO), thioredoxin reductases (TRxRs), and methionine sulfoxide reductases (Msrs) and which are named after alphabetical letters (i.e., F, H, I, K, M, N, O, P, R, S, T, V, W). These “alphabet” selenoproteins are involved in a wide range of physiological and pathogenetic processes such as antioxidant defense, anti-inflammation, anti-apoptosis, regulation of immune response, regulation of oxidative stress, endoplasmic reticulum (ER) stress, immune and inflammatory response, and toxin antagonism. In selenium deficiency, the “alphabet” selenoproteins are affected hierarchically, both with respect to the particular selenoprotein and the tissue of expression, as the brain or endocrine glands are hardly affected by Se deficiency due to their equipment with LRP2 or LRP8. Full article

Earlier studies have shown that selenomethionine (SM) supplements in broiler breeders had higher deposition in eggs, further reduced the mortality of chicken embryos, and exerted a stronger antioxidant ability in offspring than sodium selenite (SS). Since previous studies also confirmed that Se deposition in eggs was positively correlated with maternal supplementation, this study aimed to directly investigate the antioxidant activities and underlying mechanisms of SS and SM on the chicken hepatocellular carcinoma cell line (LMH). The cytotoxicity results showed that the safe concentration of SM was up to 1000 ng/mL, while SS was 100 ng/mL. In Se treatments, both SS and SM significantly elevated mRNA stability and the protein synthesis rate of glutathione peroxidase (GPx) and thioredoxin reductase (TrxR), two Se-containing antioxidant enzymes. Furthermore, SM exerted protective effects in the H₂O₂-induced oxidant stress model by reducing free radicals (including ROS, MDA, and NO) and elevating the activities of antioxidative enzymes, which performed better than SS. Furthermore, the results showed that cotreatment with SM significantly induced apoptosis induced by H₂O₂ on elevating the content of Bcl-2 and decreasing caspase-3. Moreover, investigations of the mechanism revealed that SM might exert antioxidant effects on H₂O₂-induced LMHs by activating the Nrf2 pathway and enhancing the activities of major antioxidant selenoenzymes downstream. These findings provide evidence for the effectiveness of SM on ameliorating H₂O₂-induced oxidative impairment and suggest SM has the potential to be used in the prevention or adjuvant treatment of oxidative-related impairment in poultry feeds. Full article