Bioclay Enzyme with Bimetal Synergistic Sterilization and Infectious Wound Regeneration.

Bacteria invasion is the main factor hindering the wound-healing process. However, current antibacterial therapies inevitably face complex challenges, such as the abuse of antibiotics or severe inflammation during treatment. Here, a drug-free bioclay enzyme (Bio-Clayzyme) consisting of Fe2+-tannic acid (TA) network-coated kaolinite nanoclay and glucose oxidase (GOx) was reported to destroy harmful bacteria via bimetal antibacterial therapy. At the wound site, Bio-Clayzyme was found to enhance the generation of toxic hydroxyl radicals for sterilization via cascade catalysis of GOx and Fe2+-mediated peroxidase mimetic activity. Specifically, the acidic characteristics of the infection microenvironment accelerated the release of Al3+ from kaolinite, which further led to bacterial membrane damage and amplified the antibacterial toxicity of Fe2+. Besides, Bio-Clayzyme also performed hemostasis and anti-inflammatory functions inherited from Kaol and TA. By the combination of hemostasis and anti-inflammatory and bimetal synergistic sterilization, Bio-Clayzyme achieves efficient healing of infected wounds, providing a revolutionary approach for infectious wound regeneration.

A thermo-sensitive hydrogel with prominent hemostatic effect prevents tumor recurrence via anti-anoikis-resistance.

Tumor cells can survive when detached from the extracellular matrix (ECM) or lose cell-cell connections, a phenomenon known as anoikis-resistance (AR). AR is closely associated with tumor cell metastasis and recurrence, enabling tumor cells to disseminate, migrate, and invade after detachment. To address this issue, a novel intervention method combining intraoperative hemostasis with multifunctional nanozyme driven-enhanced chemodynamic therapy (ECDT) has been proposed, which holds the potential to weaken the AR capability of tumor cells and suppress tumor recurrence. Here, a nanocomposite containing a dendritic mesoporous nanoframework with Cu2+ was developed using an anion-assisted approach after surface PEG grafting and glucose oxidase (GOx) anchoring (DMSN-Cu@GOx/PEG). DMSN-Cu@GOx/PEG was further encapsulated in a thermal-sensitive hydrogel (H@DMSN-Cu@GOx/PEG). DMSN-Cu@GOx/PEG utilizes its high peroxidase (POD) activity to elevate intracellular ROS levels, thereby weakening the AR capability of bladder cancer cells. Additionally, through its excellent catalase (CAT) activity, DMSN-Cu@GOx/PEG converts the high level of hydrogen peroxide (H2O2) catalyzed by intracellular GOx into oxygen (O2), effectively alleviating tumor hypoxia, downregulating hypoxia-inducible factor-1α (HIF-1α) expression, inhibiting epithelial-mesenchymal transition (EMT) processes, and ultimately suppressing the migration and invasion of bladder cancer cells. Interestingly, in vivo results showed that the thermosensitive hydrogel H@DMSN-Cu@GOx/PEG could rapidly gel at body temperature, forming a gel film on wounds to eliminate residual tumor tissue after tumor resection surgery. Importantly, H@DMSN-Cu@GOx/PEG exhibited excellent hemostatic capabilities, effectively enhancing tissue coagulation during post-tumor resection surgery and mitigating the risk of cancer cell dissemination and recurrence due to surgical bleeding. Such hydrogels undoubtedly possess strong surgical application. Our developed novel nanosystem and hydrogel can inhibit the AR capability of tumor cells and prevent recurrence post-surgery. This study represents the first report of using dendritic mesoporous silica-based nanoreactors for inhibiting the AR capability of bladder cancer cells and suppressing tumor recurrence post-surgery, providing a new avenue for developing strategies to impede tumor recurrence after surgery.

Liposomal Enzyme Nanoreactors Based on Nanoconfinement for Efficient Antitumor Therapy.

Enzymatic reactions can consume endogenous nutrients of tumors and produce cytotoxic species and are therefore promising tools for treating malignant tumors. Inspired by nature where enzymes are compartmentalized in membranes to achieve high reaction efficiency and separate biological processes with the environment, we develop liposomal nanoreactors that can perform enzymatic cascade reactions in the aqueous nanoconfinement of liposomes. The nanoreactors effectively inhibited tumor growth in vivo by consuming tumor nutrients (glucose and oxygen) and producing highly cytotoxic hydroxyl radicals (⋅OH). Co-compartmentalization of glucose oxidase (GOx) and horseradish peroxidase (HRP) in liposomes could increase local concentration of the intermediate product hydrogen peroxide (H2 O2 ) as well as the acidity due to the generation of gluconic acid by GOx. Both H2 O2 and acidity accelerate the second-step reaction by HRP, hence improving the overall efficiency of the cascade reaction. The biomimetic compartmentalization of enzymatic tandem reactions in biocompatible liposomes provides a promising direction for developing catalytic nanomedicines in antitumor therapy.

Biomimetic synthesis of a novel O2-regeneration nanosystem for enhanced starvation/chemo-therapy.

Glucose oxidase-mediated starvation therapy that effectively cuts off energy supply holds great promise in cancer treatment. However, high glutathione (GSH) contents and anoxic conditions severely reduce therapy efficiency and cannot fully kill cancer cells. Herein, to resolve the above problem, this study constructed a biomimetic nanosystem based on nanreproo-MnO2with porous craspedia globose-like structure and high specific surface area, and it was further modified with dopamine and folic acid to guarantee good biocompatibility and selectivity toward cancer cells. This nanosystem responsively degraded and reacted with GSH and acid to regenerate O2, which significantly increased intracellular O2levels, accelerated glucose consumption, and improved starvation therapy efficiency. Moreover, anticancer drug of camptothecin was further loaded, and notably enhanced cancer growth inhibition was obtained at very low drug concentrations. Most importantly, this novel therapy could unprecedentedly inhibit cancer cell migration to a very low ratio of 19%, and detailed cell apoptosis analyses revealed late stage apoptosis contributed most to the good therapeutic effect. This work reported a new train of thought to improve starvation therapy in biomedicine, and provided a new strategy to design targeted nanocarrier to delivery mixed drugs to overcome the restriction of starvation therapy and develop new therapy patterns.

Oncolytic Nanoreactors Producing Hydrogen Peroxide for Oxidative Cancer Therapy.

In situ generation of anticancer agents at the place of the disease is a new paradigm for cancer therapy. The production of highly potent drugs by nanoreactors through a facile synthesis pathway is demanded. We report an oncolytic nanoreactor platform loaded with the enzyme glucose oxidase (GOX) to produce hydrogen peroxide. For the first time, we realized a core-shell structure with encapsulated GOX under mild synthetic conditions, which ensured high remaining activity of GOX inside of the nanoreactor. Moreover, the nanoreactor protected the loaded GOX from proteolysis and contributed to increased thermal stability of the enzyme. The nanoreactors were effectively taken up into different cancer cells, in which they produced hydrogen peroxide by consuming intracellular glucose and oxygen, thereby leading to effective death of the cancer cells. In summary, our robust nanoreactors are a promising platform for effective anticancer therapy and sustained enzyme utilization.

Biomimetic Cascade Polymer Nanoreactors for Starvation and Photodynamic Cancer Therapy.

The selective disruption of nutritional supplements and the metabolic routes of cancer cells offer a promising opportunity for more efficient cancer therapeutics. Herein, a biomimetic cascade polymer nanoreactor (GOx/CAT-NC) was fabricated by encapsulating glucose oxidase (GOx) and catalase (CAT) in a porphyrin polymer nanocapsule for combined starvation and photodynamic anticancer therapy. Internalized by cancer cells, the GOx/CAT-NCs facilitate microenvironmental oxidation by catalyzing endogenous H2O2 to form O2, thereby accelerating intracellular glucose catabolism and enhancing cytotoxic singlet oxygen (1O2) production with infrared irradiation. The GOx/CAT-NCs have demonstrated synergistic advantages in long-term starvation therapy and powerful photodynamic therapy (PDT) in cancer treatment, which inhibits tumor cells at more than twice the rate of starvation therapy alone. The biomimetic polymer nanoreactor will further contribute to the advancement of complementary modes of spatiotemporal control of cancer therapy.

Encapsulation of glucose oxidase in Fe(III)/tannic acid nanocomposites for effective tumor ablation via Fenton reaction.

Increasing the content of reactive oxygen species (ROS) with the assistance of nanoformulations in cancer cells via the Fenton reaction is considered an effective method to treat cancer. However, the efficiency of the Fenton reaction is affected by the level of H2O2, the selection of iron ions in different nanoformulations, etc. Herein, we use FeIII-tannic acid (FeIIITA) nanocomposites as the carrier to deliver glucose oxidase (GOD) which can solve the problem of insufficient endogenous H2O2 by catalytically converting the glucose. In comparison with traditional Fe2+/Fe3+, FeIIITA nanocomposites perform higher catalytic activity in converting H2O2 to high toxic hydroxyl radicals (·OH) due to the TA-mediated reduction of Fe3+. So, the integration of GOD and TA in the construction of nanocomposites significantly enhances the efficiency of the Fenton reaction. In vitro experiments show that ·OH produced by GOD-FeIIITA nanocomposites can not only achieve a good anticancer effect at a low concentration but also promote degradability of the nanocomposites. When it is only 1.08 µg · ml-1, the cell apoptosis rate has reached 76.91%. In vivo experiments further demonstrate that GOD-FeIIITA nanocomposites can significantly inhibit tumor growth. So this work lays a good foundation for Fenton reaction-based cancer treatment.

Nano magnetic liposomes-encapsulated parthenolide and glucose oxidase for ultra-efficient synergistic antitumor therapy.

Multifunctional nanoplatforms yield extremely high synergistic therapeutic effects on the basis of low biological toxicity. Based on the unique tumor microenvironment (TME), a liposomes (Lips)-based multifunctional antitumor drug delivery system known as GOD-PTL-Lips@MNPs was synthesized for chemotherapy, chemodynamic therapy (CDT), starvation therapy, and magnetic targeting synergistic therapy. Evidence has suggested that parthenolide (PTL) can induce apoptosis and consume excessive glutathione (GSH), thereby increasing the efficacy of chemodynamic therapy. On the other hand, glucose oxidase (GOD) can consume intratumoral glucose, lower pH and increase the level of H2O2 in the tumor tissue. Integrated Fe3O4 magnetic nanoparticles (MNPs) containing Fe2+ and Fe3+ effectively catalyzes H2O2 to a highly toxic hydroxyl radical (•OH) and provide magnetic targeting. During the course of in vitro and in vivo experiments, GOD-PTL-Lips@MNPs demonstrated remarkable synergistic antitumor efficacy. In particular, in mice receiving a 14 day treatment of GOD-PTL-Lips@MNPs, tumor growth was significantly inhibited, as compared with the control group. Moreover, toxicology study and histological examination demonstrated low biotoxicity of this novel therapeutic approach. In summary, our data suggests great antitumor potential for GOD-PTL-Lips@MNPs which could provide an alternative means of further improving the efficacy of anticancer therapies.

Biomimetic Hybrid Nanozymes with Self-Supplied H+ and Accelerated O2 Generation for Enhanced Starvation and Photodynamic Therapy against Hypoxic Tumors.

Nanozymes as artificial enzymes that mimicked natural enzyme-like activities have received great attention in cancer diagnosis and therapy. Biomimetic nanozymes require more consideration regarding complicated tumor microenvironments to mimic biological enzymes, thus achieving superior nanozyme activity in vivo. Here we report a biomimetic hybrid nanozyme (named rMGB) which integrates natural enzyme glucose oxidase (GOx) with nanozyme manganese dioxide (MnO2) by mutual promotion for maximizing the enzymatic activity of MnO2 and GOx. Under hypoxia environment, we observed that MnO2 could react with endogenous H2O2 to produce O2 for enhancing the catalytic efficiency of GOx for starvation therapy. Meanwhile, we confirmed that glucose oxidation generated gluconic acid and further improved the catalytic efficiency of MnO2 subsequently. The biochemical reaction cycle, consisting of MnO2, O2, GOx, and H+, was triggered by the tumor microenvironment and accelerated each other so as to achieve self-supplied H+ and accelerate O2 generation, enhancing the starvation therapy, alleviating tumor hypoxia and accelerating the reactive oxygen species generation in photodynamic therapy. This biomimetic hybrid nanozyme would further facilitate the development of biological nanozymes for cancer treatment.

Self-Boosting Catalytic Nanoreactors Integrated with Triggerable Crosslinking Membrane Networks for Initiation of Immunogenic Cell Death by Pyroptosis.

Synthetic polymer vesicles spur novel strategies for producing intelligent nanodevices with precise and specific functions. Engineering vesicular nanodevices with tunable permeability by a general platform without involving trade-offs between structural integrity, flexibility, and functionality remains challenging. Herein, we present a general strategy to construct responsive nanoreactors based on polyion complex vesicles by integrating stimuli-responsive linkers into a crosslinking membrane network. The formulated ROS-responsive nanoreactor with self-boosting catalytic glucose oxidation could protect glucose oxidase (GOD) to achieve cytocidal function by oxidative stress induction and glucose starvation, which is ascribed to stimuli-responsive vesicle expansion without fracture and size-selective cargo release behavior. The GOD-loaded therapeutic nanoreactor induced an immunostimulatory form of cell death by pyroptosis, which has the great potential to prime anti-tumor immune responses.

Mechanism of Microbicidal Action of E-101 Solution, a Myeloperoxidase-Mediated Antimicrobial, and Its Oxidative Products.

E-101 solution is a first-in-class myeloperoxidase-mediated antimicrobial developed for topical application. It is composed of porcine myeloperoxidase (pMPO), glucose oxidase (GO), glucose, sodium chloride, and specific amino acids in an aqueous solution. Once activated, the reactive species hydrogen peroxide (H2O2), hypochlorous acid, and singlet oxygen are generated. We evaluated the treatment effects of E-101 solution and its oxidative products on ultrastructure changes and microbicidal activity against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli Time-kill and transmission electron microscopy studies were also performed using formulations with pMPO or GO omitted. The glutathione membrane protection assay was used to study the neutralization of reactive oxygen species. The potency of E-101 solution was also measured in the presence of serum and whole blood by MIC and minimal bactericidal concentration (MBC) determinations. E-101 solution demonstrated rapid bactericidal activity and ultracellular changes in MRSA and E. coli cells. When pMPO was omitted, high levels of H2O2 generated from GO and glucose demonstrated slow microbicidal activity with minimal cellular damage. When GO was omitted from the formulation, no antimicrobial activity or cellular damage was observed. Protection from exposure to E-101 solution reactive oxygen species in the glutathione protection assay was competitive and temporary. E-101 solution maintained its antimicrobial activity in the presence of inhibitory substances, such as serum and whole blood. E-101 solution is a potent myeloperoxidase enzyme system with multiple oxidative mechanisms of action. Our findings suggest that the primary site where E-101 solution exerts microbicidal action is the cell membrane, by inactivation of essential cell membrane components.

Protective effect of myricetin derivatives from Syzygium malaccense against hydrogen peroxide-induced stress in ARPE-19 cells.

Purpose: Oxidative stress is implicated in the etiology of diabetes and its debilitating complications, such as diabetic retinopathy (DR). Various flavonoids have been reported to be useful in reducing DR progression. Myricetin derivatives (F2) isolated from leaf extract of Syzygium malaccense have the potential to serve as functional food as reported previously. The present study was performed with the aim of determining the antioxidant potential and protective effect of myricetin derivatives (F2) isolated from leaf extract of S. malaccense against glucose oxidase (GO)-induced hydrogen peroxide (H2O2) production that causes oxidative stress in ARPE-19 (RPE) cells. Methods: Antioxidant properties were assessed through various radical (DPPH, ABTS, and nitric oxide) scavenging assays and determination of total phenolic content and ferric reducing antioxidant power level. ARPE-19 cells were preincubated with samples before the addition of GO (to generate H2O2). Cell viability, change in intracellular reactive oxygen species (ROS), H2O2 levels in cell culture supernatant, and gene expression were assessed. Results: F2 showed higher antioxidant levels than the extract when assessed for radical scavenging activities and ferric reducing antioxidant power. F2 protected the ARPE-19 cells against GO-H2O2-induced oxidative stress by reducing the production of H2O2 and intracellular reactive oxygen species. This was achieved by the activation of nuclear factor erythroid 2-related factor 2 (Nrf2/NFE2L2) and superoxide dismutase (SOD2), as well as downregulation of nitric oxide producer (NOS2) at the transcriptional level. Conclusions: The results showed that myricetin derivatives from S. malaccense have the capacity to exert considerable exogenous antioxidant activities and stimulate endogenous antioxidant activities. Therefore, these derivatives have excellent potential to be developed as therapeutic agents for managing DR.

Enzyme-Immobilized Chitosan Nanoparticles as Environmentally Friendly and Highly Effective Antimicrobial Agents.

Highly effective and minimally toxic antimicrobial agents have been prepared by immobilizing glucose oxidase (GOx) onto biocompatible chitosan nanoparticles (CS-NPs). CS-NPs were prepared via ionotropic gelation and used for the immobilization of GOx via approaches of covalent attachment (CA), enzyme coating (EC), enzyme precipitate coating (EPC), and magnetic nanoparticle-incorporated EPC (Mag-EPC). EPC represents an approach consisting of enzyme covalent attachment, precipitation, and cross-linking, with CA and EC being control samples while Mag-EPC was prepared by mixing magnetic nanoparticles (Mag) with enzymes during the preparation of EPC. The GOx activities of CA, EC, EPC, and Mag-EPC were 8.57, 17.7, 219, and 247 units/mg CS-NPs, respectively, representing 26 and 12 times higher activity of EPC than those of CA and EC, respectively. EPC improved the activity and stability of GOx and led to good dispersion of CS-NPs, while Mag-EPC enabled facile magnetic separation. To demonstrate the expandability of the EPC approach to other enzymes, bovine carbonic anhydrase was also employed to prepare EPC and Mag-EPC samples for their characterizations. In the presence of glucose, EPC of GOx generated H2O2 in situ, which effectively inhibited the proliferation of Staphylococcus aureus in both suspended cultures and biofilms, thereby demonstrating the potential of EPC-GOx as environmentally friendly and highly effective antimicrobial materials.

Flaminal® versus Flamazine® in the treatment of partial thickness burns: A randomized controlled trial on clinical effectiveness and scar quality (FLAM study).

Although partial thickness burns are the most frequently reported burn injuries, there is no consensus on the optimal treatment. The objective of this study was to compare the clinical effectiveness and scar quality of Flaminal® Forte to silver sulfadiazine (Flamazine®) in the treatment of partial thickness burns. In this two-arm open label multicenter randomized controlled trial, adult patients with acute partial thickness burns and an affected total body surface area of less than 30% were randomized between Flaminal® Forte and Flamazine® and followed for 12 months. Dressing changes in the Flamazine® group were performed daily, and in the Flaminal® group during the first 3 days post burn and thereafter every other day until complete wound healing or surgery. Forty-one patients were randomly allocated to Flaminal® Forte and 48 patients to Flamazine®. The primary outcome was time to wound healing, which did not differ between the groups: median 18 days with Flaminal® Forte (range 8-49 days) versus 16 days with Flamazine® (range 7-48 days; p = 0.24). Regarding the secondary outcomes during hospital admission, there were no statistically significant differences between the groups concerning need for surgery, pain scores, pruritus, or pain-related and anticipatory anxiety. More patients in the Flaminal® group developed wound colonization (78% versus 32%, p < 0.001), but the treatment groups did not differ regarding the incidence of local infections and use of systemic antibiotics. In terms of scar quality, no statistically significant differences between both treatment groups were found regarding subjective scar assessment (Patient and Observer Scar Assessment Scale (POSAS)), scar melanin and pigmentation (DermaSpectrometer®), and scar elasticity and maximal extension (Cutometer®) during 12 month postburn. In conclusion, time to wound healing did not differ, but the use of Flaminal® Forte seemed favorable because less dressing changes are needed which lowers the burden of wound care.

Targeting peroxiredoxin 1 impairs growth of breast cancer cells and potently sensitises these cells to prooxidant agents.

BACKGROUND: Our previous work has shown peroxiredoxin-1 (PRDX1), one of major antioxidant enzymes, to be a biomarker in human breast cancer. Hereby, we further investigate the role of PRDX1, compared to its close homolog PRDX2, in mammary malignant cells. METHODS: CRISPR/Cas9- or RNAi-based methods were used for genetic targeting PRDX1/2. Cell growth was assessed by crystal violet, EdU incorporation or colony formation assays. In vivo growth was assessed by a xenotransplantation model. Adenanthin was used to inhibit the thioredoxin-dependent antioxidant defense system. The prooxidant agents used were hydrogen peroxide, glucose oxidase and sodium L-ascorbate. A PY1 probe or HyPer-3 biosensor were used to detect hydrogen peroxide content in samples. RESULTS: PRDX1 downregulation significantly impaired the growth rate of MCF-7 and ZR-75-1 breast cancer cells. Likewise, xenotransplanted PRDX1-deficient MCF-7 cells presented a retarded tumour growth. Furthermore, genetic targeting of PRDX1 or adenanthin, but not PRDX2, potently sensitised all six cancer cell lines studied, but not the non-cancerous cells, to glucose oxidase and ascorbate. CONCLUSIONS: Our study pinpoints the dominant role for PRDX1 in management of exogeneous oxidative stress by breast cancer cells and substantiates further exploration of PRDX1 as a target in this disease, especially when combined with prooxidant agents.

Polymer Prodrug-Based Nanoreactors Activated by Tumor Acidity for Orchestrated Oxidation/Chemotherapy.

Therapeutic nanoreactors have been proposed to treat cancers through in situ transformation of low-toxicity prodrugs into toxic therapeutics in the body. However, the in vivo applications are limited by low tissue-specificity and different tissue distributions between sequentially injected nanoreactors and prodrugs. Herein, we construct a block copolymer prodrug-based polymersome nanoreactor that can achieve novel orchestrated oxidation/chemotherapy of cancer via specific activation at tumor sites. The block copolymers composed of poly(ethylene glycol) (PEG) and copolymerized monomers of camptothecin (CPT) and piperidine-modified methacrylate [P(CPTMA-co-PEMA)] were optimized to self-assemble into polymersomes in aqueous solution for encapsulation of glucose oxidase (GOD) to obtain GOD-loaded polymersome nanoreactors (GOD@PCPT-NR). GOD@PCPT-NR maintained inactive in normal tissues upon systemic administration. After deposition in tumor tissues, tumor acidity-triggered protonation of PPEMA segments resulted in high permeability of the polymersome membranes and oxidation reaction of diffused glucose and O2 under the catalysis of GOD. The activation of the reaction generated H2O2, improving the oxidative stress in tumors. Simultaneously, a high level of H2O2 further activated PCPTMA prodrugs, releasing active CPT drugs. High tumor oxidative stress and released CPT drugs synergistically killed cancer cells and suppressed tumor growth via oxidation/chemotherapy. Our study provides a new strategy for engineering therapeutic nanoreactors in an orchestrated fashion for cancer therapy.

Resveratrol Modulates SIRT1 and DNMT Functions and Restores LINE-1 Methylation Levels in ARPE-19 Cells under Oxidative Stress and Inflammation.

The role of epigenetic alterations in the pathogenesis of retinal degenerative diseases, including age-related macular degeneration (AMD), has been pending so far. Our study investigated the effect of oxidative stress and inflammation on DNA methyltransferases (DNMTs) and Sirtuin 1 (SIRT1) functions, as well as on long interspersed nuclear element-1 (LINE-1) methylation, in human retinal pigment epithelial (ARPE-19) cells. Therefore, we evaluated whether treatment with resveratrol may modulate DNMT and SIRT1 functions and restore changes in LINE-1 methylation. Cells were treated with 25 mU/mL glucose oxidase (GOx) or 10 µg/mL lipopolysaccharide (LPS) to mimic oxidative or inflammatory conditions, respectively. Oxidative stress decreased DNMT1, DNMT3a, DNMT3b, and SIRT1 expression (p-values < 0.05), as well as total DNMTs (-28.5%; p < 0.0001) and SIRT1 (-29.0%; p < 0.0001) activities. Similarly, inflammatory condition decreased DNMT1 and SIRT1 expression (p-values < 0.05), as well as total DNMTs (-14.9%; p = 0.007) and SIRT1 (-20.1%; p < 0.002) activities. Interestingly, GOx- and LPS-treated cells exhibited lower LINE-1 methylation compared to controls (p-values < 0.001). We also demonstrated that treatment with 10 µM resveratrol for 24 h counteracted the detrimental effect on DNMT and SIRT1 functions, and LINE-1 methylation, in cells under oxidative and inflammatory conditions. However, further studies should explore the perspectives of resveratrol as a suitable strategy for the prevention and/or treatment of retinal degenerative diseases.

Antioxidant Properties of Glial Cell-Derived Neurotrophic Factor (GDNF).

We propose an in vitro model of chronic oxidative stress based on the use of glucose oxidase. Oxidative stress modeling leads to a significant increase in the number of dead cells in culture. It was shown that the glial cell-derived neurotrophic factor exhibits a pronounced anti-oxidant effect. Preventive application of 1 ng/ml glial cell-derived neurotrophic factor significantly reduced the percentage of dead cells in culture.

Glucose oxidase facilitates osteogenic differentiation and mineralization of embryonic stem cells through the activation of Nrf2 and ERK signal transduction pathways.

Nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/heme oxygenase-1 (HO-1) signal is known to play important roles in controlling bone homeostasis. This study examined how oxidative stress affects the mineralization of embryonic stem (ES) cells by exposing them to glucose oxidase (GO), which continuously generates H2O2 at low concentrations. The roles of Nrf2/HO-1 and mitogen-activated protein kinases on osteogenesis in GO-exposed ES cells were also investigated. GO treatment at relatively low concentrations did not change the viability of ES cells, whereas it enhanced osteogenic differentiation and mineralization in the cells. GO treatment (1 mU/ml) augmented the induction of runt-related transcription factor 2 (Runx2), Nrf2, and HO-1 in ES cells. GO-mediated acceleration of Runx2 expression and mineralization was inhibited either by Nrf2 knockdown or by treating with 5 µM PD98059, an inhibitor of phospho-extracellular signal-regulated kinase (p-ERK). The GO-stimulated mineralization was also suppressed by treating the cells with reduced glutathione or catalase, but not by superoxide dismutase or N-acetyl-cysteine. Collectively, our results demonstrate that a mild oxidative stress activates Nrf2/HO-1 signaling and an ERK-mediated pathway, and facilitates the mineralization of ES cells with a corresponding increase in Runx2.

Reduced Production of Hydrogen Sulfide and Sulfane Sulfur Due to Low Cystathionine ß-Synthase Levels in Brain Astrocytes of Stroke-Prone Spontaneously Hypertensive Rats.

Stroke-prone spontaneously hypertensive rats (SHRSP/Izm; SHRSP) develop severe hypertension and die of cerebral stroke. However, the genetic mechanisms underlying their stroke susceptibility have not been clarified yet. In this study, we used astrocytes from the newborn brain cortex of spontaneously hypertensive rats (SHR/Izm; SHR) and SHRSP to find the difference of genetic characteristics. Astrocytes are known to have functions of vasodilation and nutrient uptake for neurons in the brain. The continuous generation of hydrogen peroxide (H2O2) dose-dependently causes cell death in astrocytes, and SHRSP was more vulnerable than SHR. We found that the total thiols decreased in SHRSP astrocytes but the total glutathione (GSH) did not change. Hydrogen sulfide (H2S), which is known to protect cells through anti-oxidant and vasodilatory effects, is produced by cystathionine ß-synthase (CBS) in astrocytes. We found that H2S production was significantly decreased in SHRSP as compared to SHR. This was caused by the decreasing expression of mRNA, protein and enzyme activity of CBS in astrocytes. We also found that astrocyte cell death from oxidative stress could be prevented by GYY4137 H2S donor. H2S is also known to cause protein S-sulfhydration to modify enzyme activity. Sulfane sulfur in astrocytes was significantly lower in SHRSP and decreased by CBS inhibitor. We showed that astrocytes in SHRSP vulnerable to oxidative stress may be caused by reduction of H2S through lower expression and activity of CBS.