Reactive oxygen species (ROS) are major contributors to radiation therapy-induced side effects in cancer patients. A fusion antioxidant enzyme comprising glutathione S-transferase (GST), superoxide dismutase 1 (SOD1), and a transmembrane peptide has been shown to effectively mitigate ROS-induced damage. To enhance its targeting capability, the fusion protein was further modified by incorporating a matrix metalloproteinase-2/9 substrate peptide (X) and the transmembrane peptide R9, yielding the antioxidant enzyme GST-SOD1-X-R9 (GS1XR). This modification reduced its transmembrane ability in tumor cells, thereby selectively protecting normal cells from oxidative stress. However, the use of non-human GST poses potential immunogenicity risks. In this study, we employed seamless cloning technology to construct an expression vector containing the human GST gene to replace the non-human GST gene, and then expressed and purified novel fusion antioxidant enzymes GS1R and GS1XR. The protective effects of newly constructed GS1R and GS1XR against hydrogen peroxide (H₂O₂)-induced oxidative damage in L-02 cells were then evaluated using GS1 as a control. Enzymatic activity assays revealed that the specific activity of GST in GS1XR remained unchanged compared to the unmodified protein, while SOD activity was enhanced. Exposure to 200 μmol/L H₂O₂ transiently activated the nuclear factor-erythroid 2-related factor 2 (Nrf2) pathway; however, this activation diminished after 24 h, reducing cell viability to 48.4%. Both GS1R and GS1XR effectively scavenged intracellular ROS, directly counteracting oxidative stress and promoting Nrf2 nuclear translocation, thereby activating antioxidant pathways and restoring cell viability to normal levels. The two enzymes showed comparable efficacy. In contrast, GS1, lacking transmembrane capability, was restricted to scavenging extracellular ROS and provided only limited protection. In conclusion, both novel fusion antioxidant enzymes demonstrated significant potential in safeguarding normal cells from ROS-mediated oxidative damage. The findings provide a foundation for further investigation in related field.
Humans ; Oxidative Stress/drug effects* ; Hydrogen Peroxide ; Antioxidants/metabolism* ; Glutathione Transferase/metabolism* ; Recombinant Fusion Proteins/pharmacology* ; Superoxide Dismutase-1 ; Reactive Oxygen Species/metabolism* ; Superoxide Dismutase/biosynthesis*

The caries-preventive effects of arginine have been attributed to its impact on biofilm composition and pH. Recent in vitro studies suggest that arginine also affects the production of biofilm matrix components that contribute to virulence, but this mechanism has not been investigated clinically. This randomized, placebo-controlled, triple-blind, split-mouth in situ trial assessed arginine's impact on the microbial composition, matrix architecture, and microscale pH of biofilms from caries-active patients (N = 10). We also examined whether individual differences in the pH response to arginine were related to biofilm composition and matrix structure. Biofilms were grown for four days on carriers attached to intraoral splints. Three times daily, the biofilms were treated extraorally with sucrose (5 min), followed by arginine or placebo (30 min), in a split-mouth design. After growth, the microscale biofilm pH response to sucrose was monitored by pH ratiometry. Microbial biofilm composition and carbohydrate matrix architecture were analyzed by 16S rRNA gene sequencing and fluorescence lectin-binding analysis, respectively. Arginine treatment significantly mitigated sucrose-induced pH drops, reduced total carbohydrate matrix production, and altered the spatial distribution of fucose- and galactose-containing carbohydrates. Both arginine- and placebo-treated biofilms were dominated by streptococci and Veillonella spp. Paired analyses showed a significant reduction in mitis/oralis group streptococci and a non-significant increase in several arginine metabolizers in arginine-treated biofilms. Individual pH responses were not significantly associated with the abundance of specific bacterial taxa or carbohydrate matrix components. In conclusion, arginine reduced the virulence of biofilms from caries-active patients through multiple mechanisms, including suppressing matrix carbohydrate production.
Biofilms/drug effects* ; Humans ; Arginine/pharmacology* ; Hydrogen-Ion Concentration ; Dental Caries/prevention & control* ; Male ; Female ; Adult ; Double-Blind Method ; Sucrose/pharmacology*

OBJECTIVE: To explore the protective effects and underlying mechanisms of H ₂S against lipid peroxidation-mediated carbonyl stress in the uranium-treated NRK-52E cells. METHODS: Cell viability was evaluated using CCK-8 assay. Apoptosis was measured using flow cytometry. Reagent kits were used to detect carbonyl stress markers malondialdehyde, 4-hydroxynonenal, thiobarbituric acid reactive substances, and protein carbonylation. Aldehyde-protein adduct formation and alcohol dehydrogenase, aldehyde dehydrogenase 2, aldo-keto reductase, nuclear factor E2-related factor 2 (Nrf2), and cystathionine β-synthase (CBS) expression were determined using western blotting or real-time PCR. Sulforaphane (SFP) was used to activate Nrf2. RNA interference was used to inhibit CBS expression. RESULTS: GYY4137 (an H ₂S donor) pretreatment significantly reversed the uranium-induced increase in carbonyl stress markers and aldehyde-protein adducts. GYY4137 effectively restored the uranium-decreased Nrf2 expression, nuclear translocation, and ratio of nuclear to cytoplasmic Nrf2, accompanied by a reversal of the uranium-decreased expression of CBS and aldehyde-metabolizing enzymes. The application of CBS siRNA efficiently abrogated the SFP-enhanced effects on the expression of CBS, Nrf2 activation, nuclear translocation, and ratio of nuclear to cytoplasmic Nrf2 and concomitantly reversed the SFP-enhanced effects of the uranium-induced mRNA expression of aldehyde-metabolizing enzymes. Simultaneously, CBS siRNA reversed the SFP-mediated alleviation of the uranium-induced increase in reactive aldehyde levels, apoptosis rates, and uranium-induced cell viability. CONCLUSION H ₂S induces Nrf2 activation and nuclear translocation, which modulates the expression of aldehyde-metabolizing enzymes and the CBS/H ₂S axis. Simultaneously, the Nrf2-controlled CBS/H ₂S axis may at least partially promote Nrf2 activation and nuclear translocation. These events form a cycle-regulating mode through which H ₂S attenuates the carbonyl stress-mediated NRK-52E cytotoxicity triggered by uranium.
NF-E2-Related Factor 2/genetics* ; Animals ; Hydrogen Sulfide/pharmacology* ; Rats ; Signal Transduction/drug effects* ; Lipid Peroxidation/drug effects* ; Cell Line ; Uranium/toxicity* ; Antioxidant Response Elements ; Kidney/metabolism* ; Oxidative Stress/drug effects* ; Cell Survival/drug effects* ; Apoptosis/drug effects*

OBJECTIVES: Investigating the protective effect of naringenin (NAR) on the osteogenic potential of human periodontal ligament stem cells (hPDLSCs) under oxidative stress and its related mechanisms. METHODS: The oxidative damage model of hPDLSCs was established using hydrogen peroxide (H₂O₂) andthe hPDLSCs were treated with different concentrations of NAR and 0.5 μmol/L forkhead box protein O-1 (FOXO1) inhibitor AS1842856. After that, the cell counting kit-8 (CCK8) was used to determine the optimal concentrations of H₂O₂ and NAR. The alkaline phosphatase (ALP) staining and real time fluorescent quantitative reverse transcription polymerase chain reaction (qRT-PCR) were employed to assess the expression of ALP, runt-related transcription factor 2 (RUNX2) and osteocalcin (OCN) in hPDLSCs of each group. The enzyme-linked immunosorbent assay (ELISA) and 2',7'-dichlorofluorescin diacetate (DCFH-DA) staining were utilized to evaluate the expression of reactive oxygen species (ROS), malondialdehyde (MDA) and lactate dehydrogenase (LDH) in hPDLSCs. Meanwhile, qRT-PCR and western blot were used to detect the expression levels of FOXO1 and β-catenin, both are pathway related genes and proteins. RESULTS: H₂O₂ exposure led to an increase in oxidative damage in hPDLSCs, characterized by a rise in intracellular ROS levels and increased expression of MDA and LDH (P<0.05). At the same time, the osteogenic differentiation ability of hPDLSCs decreased, as evidenced by lighter ALP staining and reduced expression levels of osteogenic differentiation-related genes ALP, RUNX2 and OCN (P<0.05). Co-treatment with NAR alleviated the oxidative damage in hPDLSCs, enhanced their antioxidant capacity, and restored their osteogenic ability. The FOXO1 inhibitor AS1842856 downregulated the expression of β-catenin (P<0.05) and significantly diminished both the antioxidant effect of NAR and its ability to restore osteogenesis (P<0.05). CONCLUSIONS NAR can enhance the antioxidant capacity of hPDLSCs by activating the FOXO1/β-catenin signaling pathway within hPDLSCs, thereby mitigating oxidative stress damage and alleviating the loss of osteogenic capacity.
Humans ; Oxidative Stress/drug effects* ; Periodontal Ligament/cytology* ; Hydrogen Peroxide ; Forkhead Box Protein O1/metabolism* ; Stem Cells/cytology* ; Flavanones/pharmacology* ; beta Catenin/metabolism* ; Osteogenesis/drug effects* ; Signal Transduction ; Core Binding Factor Alpha 1 Subunit/metabolism* ; Alkaline Phosphatase/metabolism* ; Osteocalcin/metabolism* ; Cells, Cultured ; Cell Differentiation/drug effects*

OBJECTIVES: This study aims to investigate the impact of glutathione S-transferase (GST) on the environmental adaptability of Streptococcus mutans (S. mutans). METHODS: A GST knockout strain ΔgsT was constructed. Transcriptomic sequencing was performed to analyze the gene expression differences between the wild-type S. mutans UA159 and its GST knockout strain ΔgsT. Comprehensive functional assessments, including acid tolerance assays, hydrogen peroxide challenge assays, nutrient limitation growth assays, and fluorescence in situ hybridization, were conducted to evaluate the acid tolerance, antioxidant stress resistance, growth kinetics, and interspecies competitive ability of ΔgsT within plaque biofilms. RESULTS: Compared with the wild-type S. mutans, 198 genes in ΔgsT were significantly differentially expressed and enriched in pathways related to metabolism, stress response, and energy homeostasis. The survival rate of ΔgsT in acid tolerance assays was markedly reduced (P<0.01). After 15 min of hydrogen peroxide challenge, the survival rate of ΔgsT decreased to 38.12% (wild type, 71.75%). Under nutrient-limiting conditions, ΔgsT exhibited a significantly lower final OD₆₀₀ value than the wild-type strain (P<0.05). In the biofilm competition assays, the proportion of S. mutans ΔgsT in the mixed biofilm (8.50%) was significantly lower than that of the wild type (16.89%) (P<0.05). CONCLUSIONS GST enhances the acid resistance, oxidative stress tolerance, and nutrient adaptation of S. mutans by regulating metabolism-related and stress response-related genes.
Streptococcus mutans/enzymology* ; Biofilms ; Glutathione Transferase/physiology* ; Adaptation, Physiological ; Hydrogen Peroxide/pharmacology* ; Gene Expression Regulation, Bacterial ; Oxidative Stress ; Metabolic Reprogramming

OBJECTIVE: To explore the mechanism by which ω-3 polyunsaturated fatty acids (hereinafter referred to as "ω-3") exert antioxidant stress protection and promote osteogenic differentiation in MC3T3-E1 cells, and to reveal the relationship between ω-3 and the key antioxidant stress pathway involving nuclear factor E2-related factor 2 (Nrf2) and NAD (P) H quinone oxidoreductase 1 (NQO1) in MC3T3-E1 cells. METHODS: The optimal concentration of H ₂O ₂ (used to establish the oxidative stress model of MC3T3-E1 cells in vitro) and the optimal intervention concentrations of ω-3 were screened by cell counting kit 8. MC3T3-E1 cells were divided into blank control group, oxidative stress group (H ₂O ₂), low-dose ω-3 group (H ₂O ₂+low-dose ω-3), and high-dose ω-3 group (H ₂O ₂+high-dose ω-3). After osteoblastic differentiation for 7 or 14 days, the intracellular reactive oxygen species (ROS) level was measured by fluorescence staining and flow cytometry, and the mitochondrial morphological changes were observed by biological transmission electron microscope; the expression levels of Nrf2, NQO1, heme oxygenase 1 (HO-1), Mitofusin 1 (Mfn1), and Mfn2 were detected by Western blot to evaluate the cells' antioxidant stress capacity; the expression levels of Runt-related transcription factor 2 (RUNX2) and osteocalcin (OCN) were detected by immunofluorescence staining and Western blot; osteogenic potential of MC3T3-E1 cells was evaluated by alkaline phosphatase (ALP) staining and alizarin red staining. RESULTS: Compared with the oxidative stress group, the content of ROS in the low and high dose ω-3 groups significantly decreased, and the protein expressions of Nrf2, NQO1, and HO-1 significantly increased ( P<0.05). At the same time, the mitochondrial morphology of MC3T3-E1 cells improved, and the expressions of mitochondrial morphology-related proteins Mfn1 and Mfn2 significantly increased ( P<0.05). ALP staining and alizarin red staining showed that the low-dose and high-dose ω-3 groups showed stronger osteogenic ability, and the expressions of osteogenesis-related proteins RUNX2 and OCN significantly increased ( P<0.05). And the above results showed a dose-dependence in the two ω-3 treatment groups ( P<0.05). CONCLUSION ω-3 can enhance the antioxidant capacity of MC3T3-E1 cells under oxidative stress conditions and upregulate their osteogenic activity, possibly through the Nrf2/NQO1 signaling pathway.
Oxidative Stress/drug effects* ; NF-E2-Related Factor 2/metabolism* ; NAD(P)H Dehydrogenase (Quinone)/metabolism* ; Animals ; Mice ; Osteogenesis/drug effects* ; Cell Differentiation/drug effects* ; Fatty Acids, Omega-3/pharmacology* ; Signal Transduction/drug effects* ; Osteoblasts/drug effects* ; Reactive Oxygen Species/metabolism* ; Cell Line ; Hydrogen Peroxide/pharmacology* ; Core Binding Factor Alpha 1 Subunit/metabolism* ; Antioxidants/pharmacology* ; Heme Oxygenase-1/metabolism*

OBJECTIVE: To analyze the influences of dihydromyricetin on the proliferation and apoptosis of chondrocytes in osteoarthritis induced by hydrogen peroxide (H₂O₂) through reactive oxygen species (ROS)/p38 mitogen activated protein kinase (p38-MAPK) pathway. METHODS: Five C57BL/6J mice were euthanized by cervical dislocation after anesthesia. Chondrocytes were extracted and cultured.After passage, the chondrocytes were divided into control group, H2O2 group (0.8 μmol·L^-1 H₂O₂), dihydromyricetin low concentration group (0.8 μmol·L^-1 H₂O₂+20 μmol·L^-1 dihydromyricetin), dihydromyricetin high concentration group (0.8 μmol·L^-1 H₂O₂+80 μmol·L^-1 dihydromyricetin), and ROS inhibitor N-acetylcysteine (NAC) group (0.8 μmol·L^-1 H₂O₂+5 mmol·L^-1 NAC). The activity of chondrocytes was measured by methyl thiazolyl tetrazolium (MTT) assay. The apoptosis rate of chondrocytes was measured by Hoechst 33342 method. The level of ROS in chondrocytes was measured by 2, 7-dichlorofluorescein diacetate (DCFH-DA) fluorescence probe.The level of Type II collagen α1 (Col2α1) mRNA was measured by qRT-PCR.And the expression of Col2α1, p-p38-MAPK/p38-MAPK, B cell lymphoma gene-2 (Bcl-2) and Bcl-2 associated X protein (Bax) proteins was detected by Western blot. RESULTS: The chondrocytes showed swirling fibrous mass, and the expression of COL2α was positive. Compared with the control group, the chondrocyte viability, apoptosis rate, ROS fluorescence intensity, p-p38-MAPK/p38-MAPK, and the expression of Bax protein in H2O22 group increased, the level of Col2α1 mRNA, and the expression of Col2α1 and Bcl-2 proteins decreased (P<0.05). Compared with H₂O₂ group, the chondrocyte viability, apoptosis rate, ROS fluorescence intensity, p-p38-MAPK/p38-MAPK, and the expression of Bax protein in dihydromyricetin low concentration group, dihydromyricetin high concentration group, and NAC group decreased, the level of Col2α1 mRNA, and the expression of Col2α1 and Bcl-2 proteins increased (P<0.05). CONCLUSION Dihydromyricetin may inhibit chondrocyte apoptosis, inflammatory reaction and oxidative stress by inhibiting ROS/p38-MAPK pathway. Dihydromyricetin may be a potential drug for treating osteoarthritis.
Animals ; Chondrocytes/metabolism* ; Apoptosis/drug effects* ; Hydrogen Peroxide/toxicity* ; Osteoarthritis/physiopathology* ; Mice, Inbred C57BL ; Reactive Oxygen Species/metabolism* ; Mice ; Flavonols/pharmacology* ; p38 Mitogen-Activated Protein Kinases/genetics* ; Cell Proliferation/drug effects* ; Male ; Signal Transduction/drug effects* ; MAP Kinase Signaling System/drug effects* ; Cells, Cultured

OBJECTIVE: To investigate the preparation of decellularized small intestinal submucosa (dSIS) sponge scaffolds with chelated strontium (Sr) ions at different pH values, and to select the appropriate pH values for synthesizing Sr/dSIS scaffolds using the physicochemical properties and biocompatibility of the scaffolds as evaluation indexes. METHODS: (1) Sr/dSIS scaffolds preparation and grouping: After mixing dSIS solution and strontium chloride solution in equal volumes, adjusting pH of the solution to 3, 5, 7, and 9 respectively, porous scaffolds were prepared by freeze-drying method after full reaction at 37℃, which were named Sr/dSIS-3, -5, -7, and -9 respectively, and the dSIS scaffolds were used as the control group. (2) Physicochemical property evaluation: The bulk morphology of the scaffolds was observed in each group, the microscopic morphology analyzed by scanning electron microscopy, and the porosity and pore size determined, the surface elements analyzed by energy spectroscopy, the structure of functional groups analyzed by infrared spectroscopy, the chelation rate determined by atomic spectrophotometry, the water absorption rate detected by using specific gravity method, and the compression strength evaluated by universal mechanical testing machine.(3) Biocompatibility evaluation: The cytotoxicity and proliferative effect to bone mesenchymal stem cells (BMSCs) of each group were evaluated by Calcein-AM/PI double staining method. RESULTS: Scanning electron microscopy showed that the scaffolds of each group had an interconnected three-dimensional porous structure with no statistical difference in pore size and porosity. Energy spectrum analysis showed that strontium could be detected in Sr/dSIS-5, -7 and -9 groups, and strontium was uniformly distributed in the scaffolds. Functional group analysis further supported the formation of chelates in the Sr/dSIS-5, -7 and -9 groups. Chelation rate analysis showed that the Sr/dSIS-7 group had the highest strontium chelation rate, which was statistically different from the other groups (P < 0.05). The scaffolds in all the groups had good water absorption. The scaffolds in Sr/dSIS-5, -7 and -9 groups showed significantly improved mechanical properties compared with the control group (P < 0.05). The scaffolds in all the groups had good biocompatibility, and the Sr/dSIS-7 group showed the best proliferation of BMSCs. CONCLUSION When pH was 7, the Sr/dSIS scaffolds showed the highest strontium chelation rate and the best proliferation effect of BMSCs, which was the ideal pH value for the preparation of the Sr/dSIS scaffolds.
Tissue Scaffolds/chemistry* ; Biocompatible Materials ; Strontium/pharmacology* ; Ions ; Hydrogen-Ion Concentration ; Tissue Engineering/methods* ; Porosity

Xenogenic organ transplantation has been considered the most promising strategy in providing possible substitutes with the physiological function of the failing organs as well as solving the problem of insufficient donor sources. However, the xenograft, suffered from immune rejection and ischemia-reperfusion injury (IRI), causes massive reactive oxygen species (ROS) expression and the subsequent cell apoptosis, leading to the xenograft failure. Our previous study found a positive role of PPAR-γ in anti-inflammation through its immunomodulation effects, which inspires us to apply PPAR-γ agonist rosiglitazone (RSG) to address survival issue of xenograft with the potential to eliminate the excessive ROS. In this study, xenogenic bioroot was constructed by wrapping the dental follicle cells (DFC) with porcine extracellular matrix (pECM). The hydrogen peroxide (H₂O₂)-induced DFC was pretreated with RSG to observe its protection on the damaged biological function. Immunoflourescence staining and transmission electron microscope were used to detect the intracellular ROS level. SD rat orthotopic transplantation model and superoxide dismutase 1 (SOD1) knockout mice subcutaneous transplantation model were applied to explore the regenerative outcome of the xenograft. It showed that RSG pretreatment significantly reduced the adverse effects of H₂O₂ on DFC with decreased intracellular ROS expression and alleviated mitochondrial damage. In vivo results confirmed RSG administration substantially enhanced the host's antioxidant capacity with reduced osteoclasts formation and increased periodontal ligament-like tissue regeneration efficiency, maximumly maintaining the xenograft function. We considered that RSG preconditioning could preserve the biological properties of the transplanted stem cells under oxidative stress (OS) microenvironment and promote organ regeneration by attenuating the inflammatory reaction and OS injury.
Mice ; Humans ; Rats ; Animals ; Swine ; PPAR gamma/pharmacology* ; Reactive Oxygen Species/pharmacology* ; Heterografts ; Hydrogen Peroxide/pharmacology* ; Rats, Sprague-Dawley ; Rosiglitazone/pharmacology* ; Oxidative Stress

Objective To investigate the effect of H₂O₂-induced oxidative stress on autophagy and apoptosis of human bone marrow mesenchymal stem cells (hBMSCs). Methods hBMSCs were isolated and cultured. The cells were divided into control group, 3-MA group, H₂O₂ group, H₂O₂ combined with 3-MA group. DCFH-DA staining was used to analyze the level of reactive oxygen species (ROS). hBMSCs were treated with 0, 50, 100, 200, 400 μmol/L H₂O₂, and then the cell viability was detected by CCK-8 assay. The level of autophagy was detected by monodansylcadaverine (MDC) staining and LysoTracker Red staining. The cell apoptosis was detected by flow cytometry. Western blotting was used to detect the expression of beclin 1, mTOR, phosphorylated mTOR (p-mTOR), cleaved caspase-3(c-caspase-3) and caspase-3 proteins. Results Compared with the control group and 3-MA group, ROS level and autophagosomes were increased and the proliferation and apoptosis were decreased in H₂O₂ group. The protein expression of beclin 1, mTOR, c-caspase-3 was up-regulated, while the p-mTOR was down-regulated. Compared with the 3-MA group, the H₂O₂ combined with 3-MA group also had an increased ROS level and autophagosomes, but not with significantly increased apoptosis rate; The protein expression of beclin 1, mTOR, c-caspase-3 was up-regulated, and the p-mTOR was down-regulated. Conclusion H₂O₂ can induce hMSCs to trigger oxidative stress response. It enhances the autophagy and inhibits the proliferation and apoptosis of hBMSCs.
Humans ; Beclin-1/metabolism* ; Caspase 3/metabolism* ; Reactive Oxygen Species/metabolism* ; Hydrogen Peroxide/pharmacology* ; Apoptosis ; TOR Serine-Threonine Kinases/metabolism* ; Oxidative Stress ; Autophagy ; Mesenchymal Stem Cells/metabolism* ; Cell Proliferation