Increased H2O2 Production Research Articles

Neuregulin 4 Downregulation Alters Mitochondrial Morphology and Induces Oxidative Stress in 3T3-L1 Adipocytes

Neuregulin 4 (Nrg4) is an adipokine that belongs to the epidermal growth factor family and binds to ErbB4 tyrosine kinase receptors. In 3T3-L1 adipocytes, the downregulation of Nrg4 expression enhances inflammation and autophagy, resulting in insulin resistance. Here, we searched for the causes of this phenotype. Nrg4 knockdown (Nrg4 KD) adipocytes showed a significant reduction in mitochondrial content and elongation, along with a lower content of the mitochondria fusion protein mitofusin 2 (MFN2), and increased H2O2 production compared to the control scrambled cells (Scr). The antioxidant N-acetylcysteine reversed the oxidative stress and reduced the gene expression of the pro-inflammatory cytokine tumor necrosis factor α (TNFα). Nrg4 KD adipocytes showed enhanced lipolysis and reduced lipogenesis, in addition to a significant reduction in several intermediates of the Krebs cycle. In summary, Nrg4 downregulation in adipocytes affects mitochondrial content and functioning, causing impaired cellular metabolism, which in turn results in oxidative stress, inflammation, and insulin resistance.

Nandrolone Abuse Prior to Head Trauma Mitigates Endoplasmic Reticulum Stress, Mitochondrial Bioenergetic Deficits, and Markers of Neurodegeneration.

The abuse of synthetic steroids, such as nandrolone decanoate (ND), is often associated with violent behavior, increasing the risk of traumatic brain injury (TBI). After a TBI, proteins like APP, β-amyloid peptide-42 (Aβ42), and phosphorylated tau (pTau) accumulate and trigger endoplasmic reticulum (ER) stress associated with an unfolded protein response (UPR). The involvement of mitochondrial bioenergetics in this context remains unexplored. We interrogate whether the abuse of ND before TBI alters the responses of ER stress and mitochondrial bioenergetics in connection with neurodegeneration and memory processing in mice. Male CF1 adult mice were administered ND (15mg/kg) or vehicle (VEH) s.c. for 19days, coinciding with the peak day of aggressive behavior, and then underwent cortical controlled impact (CCI) or sham surgery. Spatial memory was assessed through the Morris water maze task (MWM) post-TBI. In synaptosome preparations, i) we challenged mitochondrial complexes (I, II, and V) in a respirometry assay, employing metabolic substrates, an uncoupler, and inhibitors; and ii) assessed molecular biomarkers through Western blot. TBI significantly increased APP, Aβ42, and pTauSer396 levels, along with ER-stress proteins, GRP78, ATF6, and CHOP, implying it primed apoptotic signaling. Concurrently, TBI reduced mitochondrial Ca2+ efflux in exchange with Na+, disturbed the formation/dissipation of membrane potential, increased H2O2 production, decreased biogenesis (PGC-1⍺ and TOM20), and ATP biosynthesis coupled with oxygen consumption. Unexpectedly, ND abuse before TBI attenuated the elevations in APP, Aβ42, and pTauSer396, accompanied by a decrease in GRP78, ATF6, and CHOP levels, and partial normalization of mitochondrial-related endpoints. A principal component analysis revealed a key hierarchical signature featuring mitochondrial Ca2+ efflux, CHOP, GRP78, TOM20, H2O2, and bioenergetic efficiency as a unique variable (PC1) able to explain the memory deficits caused by TBI, as well as the preservation of memory fitness induced by prior ND abuse.

Endothelial protein disulfide isomerase A1 enhances membrane stiffness and platelet-endothelium interaction in hyperglycemia via SLC3A2 and LAMC1

BackgroundDiabetes carries an increased risk of cardiovascular disease and thromboembolic events. Upon endothelial dysfunction, platelets bind to endothelial cells to precipitate thrombus formation; however, it is unclear which surface proteins regulate platelet-endothelium interaction. We and others have shown that peri/epicellular protein disulfide isomerase A1 (pecPDI) influences the adhesion and migration of vascular cells. ObjectivesWe investigated whether pecPDI regulates adhesion-related molecules on the surface of endothelial cells and platelets that influence the binding of these cells in hyperglycemia. MethodsImmunofluorescence was used to assess platelet-endothelium interaction in vitro, cytoskeleton reorganization, and focal adhesions. Hydrogen peroxide production was assessed via Amplex Red assays (ThermoFisher Scientific). Cell biophysics was assessed using atomic force microscopy. Secreted proteins of interest were identified through proteomics (secretomics), and targets were knocked down using small interfering RNA. Protein disulfide isomerase A1 (PDI) contribution was assessed using whole-cell PDI or pecPDI inhibitors or small interfering RNA. ResultsPlatelets of healthy donors adhered more onto hyperglycemic human umbilical vein endothelial cells (HUVECs). Endothelial, but not platelet, pecPDI regulated this effect. Hyperglycemic HUVECs showed marked cytoskeleton reorganization, increased H2O2 production, and elongated focal adhesions. Indeed, hyperglycemic HUVECs were stiffer compared with normoglycemic cells. PDI and pecPDI inhibition reversed the abovementioned processes in hyperglycemic cells. A secretomics analysis revealed 8 proteins secreted in a PDI-dependent manner by hyperglycemic cells. Among these, we showed that genetic deletion of LAMC1 and SLC3A2 decreased platelet-endothelium interaction and did not potentiate the effects of PDI inhibitors. ConclusionEndothelial pecPDI regulates platelet-endothelium interaction in hyperglycemia through adhesion-related proteins and alterations in endothelial membrane biophysics.

A new colorimetric lactate biosensor based on CUPRAC reagent using binary enzyme (lactate-pyruvate oxidases)-immobilized silanized magnetite nanoparticles

A novel optical lactate biosensor is presented that utilizes a colorimetric interaction between H2O2 liberated by a binary enzymatic reaction and bis(neocuproine)copper(II) complex ([Cu(Nc)2]2+) known as CUPRAC (cupric reducing antioxidant capacity) reagent. In the first step, lactate oxidase (LOx) and pyruvate oxidase (POx) were separately immobilized on silanized magnetite nanoparticles (SiO2@Fe3O4 NPs), and thus, 2 mol of H2O2 was released per 1 mol of the substrate due to a sequential enzymatic reaction of the mixture of LOx-SiO2@Fe3O4 and POx-SiO2@Fe3O4 NPs with lactate and pyruvate, respectively. In the second step, the absorbance at 450 nm of the yellow-orange [Cu(Nc)2]+ complex formed through the color reaction of enzymatically produced H2O2 with [Cu(Nc)2]2+ was recorded. The results indicate that the developed colorimetric binary enzymatic biosensor exhibits a broad linear range of response between 0.5 and 50.0 µM for lactate under optimal conditions with a detection limit of 0.17 µM. The fabricated biosensor did not respond to other saccharides, while the positive interferences of certain reducing compounds such as dopamine, ascorbic acid, and uric acid were minimized through their oxidative removal with a pre-oxidant (NaBiO3) before enzymatic and colorimetric reactions. The fabricated optical biosensor was applied to various samples such as artificial blood, artificial/real sweat, and cow milk. The high recovery values (close to 100%) achieved for lactate-spiked samples indicate an acceptable accuracy of this colorimetric biosensor in the determination of lactate in real samples. Due to the increase in H2O2 production with the bienzymatic lactate sensor, the proposed method displays double-fold sensitivity relative to monoenzymatic biosensors and involves a neat color reaction with cupric-neocuproine having a clear stoichiometry as opposed to the rather indefinite stoichiometry of analogous redox dye methods.Graphical

Nitrogen‐Rich Carbon Dot‐Mediated n→π* Electronic Transition in Carbon Nitride for Superior Photocatalytic Hydrogen Peroxide Production

AbstractSolar‐driven synthesis of hydrogen peroxide (H2O2) through photocatalysis stands out as a promising avenue for sustainable energy generation, marked by environmental friendliness and industrial feasibility. However, the inherent limitations of carbon nitride (CN) in photocatalytic H2O2 production significantly impede their performance. Herein, a novel 0D/2D carbon dots‐modified CN nanosheet heterojunction (CDsMCN) is introduced, synthesized through a hydrothermal‐calcination tandem strategy induced by CDs derived from melamine. This innovative technique enhances the n→π* electronic transition in CDsMCN, accelerating the separation efficiency of electron‐hole pairs, boosting oxygen adsorption, and promoting a highly selective 2e− ORR. Comparative to pristine CN, CDs10MCN exhibited a remarkable tenfold increase in H2O2 production, reaching an impressive 1.48 mmol L−1. Furthermore, CDs10MCN demonstrates exceptional stability, maintaining its catalytic efficiency at the initial level over four consecutive cycles. The notable achievement of a molar selectivity of H2O2 ≈80% at an onset potential of 0.6 V (vs RHE) underscores its exceptional ability to produce the desired product selectively. Advanced in situ characterization together with DFT calculations revealed that the ultrathin CDs10MCN nanosheet heterojunction with enhanced n→π* electronic transition improves its optical properties, reduces bandgap, facilitates fast charge migration, and increases photocatalytic H2O2 performance, thereby serving as a promising candidate for advanced catalytic applications.

Selenium alleviates growth characteristics, plant pigments, photosynthetic and antioxidant capacity of basil (Ocimum basilicum L.) under low temperature

Se in optimal concentrations may help to expand the plant tolerance to the different abiotic stresses. In this regard, the effect of foliar application of sodium selenate (0, 2, 4, and 6 mg of Na2SeO4) at two temperature conditions: 1. Optimal temperature (OT, 26 ± 3 °C) and 2. Cold temperature (CT, 13 ± 3 °C) was compared. The results showed that under CT, fresh and dry weight, leaf area, and length of pre-treated plant with 2 mg.L−1 Se were more suitable than untreated plants, although selenium under OT declined these characteristics. The pre-treatment of 2 mg. L−1 of Se under CT was conducive to, the 6.75% dry weight higher than that non-treated plants with Se under low temperature conditions. Also under CT conditions, pretreatment of plants with 2 mg. L−1 Se increased H2O2 production by 102% compared to non-treated plants with selenium. However, it was about 25.56% lower than the untreated plants with selenium under CT. It is interesting to note that under the CT conditions, pretreatment of 2 mg. L −1 Se reduced the content of MDA by 10.28% compared to the same temperature conditions and no Se pretreatment. Foliar application of 2 mg.L−1 Se is recommended to improve basil endure in CT and biofortification with Se under both OT and CT.

Activation of Piezo-1 Prevents Human Microvascular Endothelial Dysfunction During Acute Inhibition of Ceramide Formation

Despite the well-known damaging effects of elevated intracellular ceramides on human microvascular function, our recent work has shown that inhibition of ceramide formation through neutral sphingomyelinase (NSmase) promotes endothelial dysfunction in arterioles from healthy adults, manifested as endothelial production of hydrogen peroxide (H2O2), rather than nitric oxide (NO), in response to flow (flow-induced dilation; FID). Recent evidence suggests that ceramide prevents inactivation of Piezo-1, a shear-sensitive Ca2+ channel and inhibition of Piezo-1 reduces endothelial nitric oxide synthase (eNOS) activation in response to flow. Together, we hypothesized that ceramide-induced Piezo-1 activation is required to maintain NO-mediated FID in human microvessels and thus agonism of Piezo-1 during NSmase inhibition will prevent endothelial dysfunction. Arterioles (100-250μm) from healthy adults were dissected from discarded surgical adipose tissue. Vessels were cannulated in organ chambers, pre-constricted with endothelin-1, and changes in internal diameter in response to increases in flow were measured with videomicroscopy. Peroxy yellow 1 (PY1) fluorescent probe was used to assess endothelial H2O2 production in human umbilical vein endothelial cells (HUVECs). Mean% maximal dilation or fluorescent intensity±SE with two-way repeated measures ANOVA is reported. FID was preserved with Piezo-1 agonism (Yoda-1, 1μM, 30min) during NSmase inhibition (GW4869 4μM, 30min; 73±16.8, n=4 vs control 73±8.2, n=9; p>0.05), however FID was diminished in the presence of the eNOS inhibitor L-NAME (100μM; -2.6±11.3, n=5; p<0.05). A similar switch to NO-mediated FID was seen with C2-ceramide (5μM)+GW4869 (70.1±9.7 vs +L-NAME -3±9.7, n=4 both; p<0.05). NSmase inhibition increased H2O2 production in HUVECs (5.2±7.4 vs 83.0±31.6, n=6; p<0.05), an effect that was diminished with Yoda-1 (5.1±7.5, n=4; p<0.05) and C2-ceramide (10.7±9.2, n=5; p<0.05). These data suggest a role for Piezo-1 in NSmase-induced NO-signaling and provide mechanistic insight into how ceramide may exert beneficial effects within the human microvasculature. This research is supported by the National Institute of Health (NHLBI) R01HL160752 (JKF) and the American Heart Association (AHA) Predoctoral Fellowship 909315 (GSK). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of VBIT-4 on the functional activity of isolated mitochondria and cell viability

VBIT-4 is a new inhibitor of the oligomerization of VDAC proteins of the outer mitochondrial membrane preventing the development of oxidative stress, mitochondrial dysfunction, and cell death in various pathologies. However, as a VDAC inhibitor, VBIT-4 may itself cause mitochondrial dysfunction in healthy cells. The article examines the effect of VBIT-4 on the functional activity of rat liver mitochondria and cell cultures. We have demonstrated that high concentrations of VBIT-4 (15–30 μM) suppressed mitochondrial respiration in state 3 and 3UDNP driven by substrates of complex I and II. VBIT-4 induced depolarization of organelles fueled by substrates of complex I but not complex II of the respiratory chain. VBIT-4 has been found to inhibit the activity of complexes I, III, and IV of the respiratory chain. Molecular docking demonstrated that VBIT-4 interacts with the rotenone-binding site in complex I with similar affinity. 15–30 μM VBIT-4 caused an increase in H2O2 production in mitochondria, decreased the Ca2+ retention capacity, but increased the time of Ca2+-dependent mitochondrial swelling. We have found that the incubation of breast adenocarcinoma (MCF-7) with 30 μM VBIT-4 for 48 h led to the decrease of the mitochondrial membrane potential, an increase in ROS production and death of MCF-7 cells. The mechanism of action of VBIT-4 on mitochondria and cells is discussed.

Enhancing photocatalytic H2O2 production with Au co-catalysts through electronic structure modification

Gold-based co-catalysts are a promising class of materials with potential applications in photocatalytic H2O2 production. However, current approaches with Au co-catalysts show limited H2O2 production due to intrinsically weak O2 adsorption at the Au site. We report an approach to strengthen O2 adsorption at Au sites, and to improve H2O2 production, through the formation of electron-deficient Auδ+ sites by modifying the electronic structure. In this case, we report the synthesis of TiO2/MoSx-Au, following selective deposition of Au onto a MoSx surface which is then further anchored onto TiO2. We further show that the catalyst achieves a significantly increased H2O2 production rate of 30.44 mmol g−1 h−1 in O2-saturated solution containing ethanol. Density functional theory calculations and X-ray photoelectron spectroscopy analysis reveal that the MoSx mediator induces the formation of electron-deficient Auδ+ sites thereby decreasing the antibonding-orbital occupancy of Au-Oads and subsequently enhancing O2 adsorption. This strategy may be useful for rationally designing the electronic structure of catalyst surfaces to facilitate artificial photosynthesis.

Insight on magnetic nitrogen-doped graphene oxide composite electrode constructing heterogeneous Electro-Fenton system for treating organophosphorus pesticide wastewater

The treatment of organic phosphorus pesticide (OPP) wastewater faces challenges such as incomplete degradation and low reaction efficiency. While heterogeneous electro-Fenton (Hetero-EF) has emerged as the preferred technology for addressing these issues due to its high treatment efficiency, further optimization is still necessary. This study used a one-pot hydrothermal method to prepare magnetic nitrogen-doped graphene oxide (Fe3O4@N-GO) composite electrodes to construct a novel Hetero-EF system. Dimethoate (DIM) was chosen as the representative pollutant to investigate the effects of parameters such as current density, pH, electrode spacing, and loading amount on degradation efficiency. The results demonstrated complete degradation of DIM within 40 min. Density functional theory (DFT) calculations and intermediate product analysis revealed that the reactive sites for DIM degradation were the P=S and P=S bonds, involving both hydrolysis and •OH pathways, with a decrease in toxicity of degradation products observed. Compared to graphite electrodes, Fe3O4@N-GO composite electrodes significantly increased H2O2 production, achieving complete DIM degradation even after 5 cycles, with a phosphate conversion rate of 30–40 %. This study highlights the innovative strategy of the Hetero-EF system in its significant application value for OPP treatment.

Abstract 484: Enhancing therapeutic responses in NSCLC using iron-oxide nanoparticles combined with pharmacological ascorbate

Abstract High dose Vitamin C (pharmacological ascorbate; P-AscH‒ > 20 mM plasma levels) given intravenously (I.V.), has made a remarkable re-emergence as an adjuvant to combined modality approaches in cancer therapy. P-AscH‒ can be readily oxidized in the presence of redox active metals (i.e., P-AscH‒ serves as an iron reducing agent), which can result in increased fluxes of H2O2. This chemical phenomenon allows for the tumor-selective enhancement of chemo-radiation in NSCLC. We hypothesized that enhancing labile Fe2+ in cancer cells using iron-oxide nanoparticles (ferumoxytol, FMX) can increase the effectiveness of P-AscH‒ in enhancing cancer cell sensitivity to chemo-radiation in NSCLC by increasing H2O2 production. To test this hypothesis, we performed clonogenic cell survival assays in-vitro. To test the role of H2O2 in the combined effect of P-AscH‒ and FMX, we developed lentiviral-based doxycycline-inducible overexpression models for catalase, and to determine the changes in Fe, we used fluorescent probes that specifically detect changes in labile Fe2+. Results from these experiments showed FMX enhanced clonogenic cell killing in NSCLC. Furthermore, catalase overexpression inhibited this effect, suggesting that enhanced H2O2 production plays a central role in the additive effect of P-AscH- and FMX. Finally, staining the cells with the fluorescent iron probes showed that FMX enhanced labile Fe2+ in cells treated with P-AscH‒. These studies continue to support the hypothesis that H2O2 plays a significant role in P-AscH‒ toxicity in cancer cells that can be exacerbated using iron oxide nanoparticles. Future studies will test these findings in-vivo using preclinical xenograft models. (supported by P01 CA217797, P30 CA086862, T32 CA078586, and P01 CA244091). Citation Format: Mekhla Singhania, Miachael S. Petronek, Casey F. Pulliam, Kranti A. Mapuskar, Amira Zaher, Douglas R. Spitz. Enhancing therapeutic responses in NSCLC using iron-oxide nanoparticles combined with pharmacological ascorbate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 484.

The application of ferrous and graphitic N modified graphene-based composite cathode material in the bio-electro-Fenton system driven by sediment microbial fuel cells to degrade methyl orange

In this work, the ferrous (Fe2+) and graphitic N modified graphene-based composite cathode materials (N-rGO/Fe3O4) were developed through an in-situ reduction method, aiming to facilitate the two-electron pathway in the oxidation-reduction process. This approach generated a specific concentration of H2O2, enabling the construction of a sediment bio-electro-Fenton system using Fe2+ released from the cathode materials. Notably, this system operates without the need for proton exchange membranes. During the cathode material preparation, the utilization of Fe2+ as a reduction agent for graphene oxide (GO), triggered ammonia water to form graphitic N in graphene sheets. This addition enhanced the two-electron pathway, resulting in increased H2O2 production. Specifically, when the Fe2+ concentration was maintained at 0.1 mol/L, precise preparation of N-rGO/Fe3O4 occurred, leading to a maximum output voltage of 0.528 V and a maximum power density of 178.17 mW/m2. The degradation of methyl orange (MO) reached 68.91% within a 25-h period, a phenomenon contributed to the presence of graphitic N in the graphene sheets. H2O2, a byproduct of the two-electron pathway in cathode oxidation reduction reaction, played a crucial role in constructing the bio-electro-Fenton system. This system, in conjunction with Fe2+ released from N-rGO/Fe3O4, facilitated the complete degradation process of MO.

A single chemotherapy administration induces muscle atrophy, mitochondrial alterations and apoptosis in breast cancer patients.

Breast cancer patients are commonly treated with sequential administrations of epirubicin-cyclophosphamide (EC) and paclitaxel (TAX). The chronic effect of this treatment induces skeletal muscle alterations, but the specific effect of each chemotherapy agent is unknown. This study aimed to investigate the effect of EC or TAX administration on skeletal muscle homeostasis in breast cancer patients. Twenty early breast cancer patients undergoing EC followed by TAX chemotherapies were included. Two groups of 10 women were established and performed vastus lateralis skeletal muscle biopsies either before the first administration (pre) of EC (50±14years) or TAX (50±16years) and 4days later (post). Mitochondrial respiratory capacity recording, reactive oxygen species production, western blotting and histological analyses were performed. Decrease in muscle fibres cross-sectional area was only observed post-EC (-25%; P<0.001), associated with a reduction in mitochondrial respiratory capacity for the complex I (CI)-linked substrate state (-32%; P=0.001), oxidative phosphorylation (OXPHOS) by CI (-35%; P=0.002), CI&CII (-26%; P=0.022) and CII (-24%; P=0.027). If H2 O2 production was unchanged post-EC, an increase was observed post-TAX for OXPHOS by CII (+25%; P=0.022). We found a decrease in makers of mitochondrial content, as shown post-EC by a decrease in the protein levels of citrate synthase (-53%; P<0.001) and VDAC (-39%; P<0.001). Despite no changes in markers of mitochondrial fission, a decrease in the expression of a marker of mitochondrial inner-membrane fusion was found post-EC (OPA1; -60%; P<0.001). We explored markers of mitophagy and found reductions post-EC in the protein levels of PINK1 (-63%; P<0.001) and Parkin (-56%; P=0.005), without changes post-TAX. An increasing trend in Bax protein level was found post-EC (+96%; P=0.068) and post-TAX (+77%; P=0.073), while the Bcl-2 level was decreased only post-EC (-52%; P=0.007). If an increasing trend in TUNEL-positive signal was observed post-EC (+68%; P=0.082), upregulation was highlighted post-TAX (+86%; P<0.001), suggesting activation of the apoptosis process. We demonstrated that a single administration of EC induced, in only 4days, skeletal muscle atrophy and mitochondrial alterations in breast cancer patients. These alterations were characterized by reductions in mitochondrial function and content as well as impairment of mitochondrial dynamics and an increase in apoptosis. TAX administration did not worsen these alterations as this group had already received EC during the preceding weeks. However, it resulted in an increased apoptosis, likely in response to the increased H2 O2 production.

Redox differences between rat neonatal and adult cardiomyocytes under hypoxia

It is generally accepted that oxidative stress plays a key role in the development of ischemia-reperfusion injury in ischemic heart disease. However, the mechanisms how reactive oxygen species trigger cellular damage are not fully understood. Our study investigates redox state and highly reactive substances within neonatal and adult cardiomyocytes under hypoxia conditions. We have found that hypoxia induced an increase in H2O2 production in adult cardiomyocytes, while neonatal cardiomyocytes experienced a decrease in H2O2 levels. This finding correlates with our observation of the difference between the electron transport chain (ETC) properties and mitochondria amount in adult and neonatal cells. We demonstrated that in adult cardiomyocytes hypoxia caused the significant increase in the ETC loading with electrons compared to normoxia. On the contrary, in neonatal cardiomyocytes ETC loading with electrons was similar under both normoxic and hypoxic conditions that could be due to ETC non-functional state and the absence of the electrons transfer to O2 under normoxia. In addition to the variations in H2O2 production, we also noted consistent pH dynamics under hypoxic conditions. Notably, the pH levels exhibited a similar decrease in both cell types, thus, acidosis is a more universal cellular response to hypoxia. We also demonstrated that the amount of mitochondria and the levels of cardiac isoforms of troponin I, troponin T, myoglobin and GAPDH were significantly higher in adult cardiomyocytes compared to neonatal ones. Remarkably, we found out that under hypoxia, the levels of cardiac isoforms of troponin T, myoglobin, and GAPDH were elevated in adult cardiomyocytes, while their level in neonatal cells remained unchanged. Obtained data contribute to the understanding of the mechanisms of neonatal cardiomyocytes’ resistance to hypoxia and the ability to maintain the metabolic homeostasis in contrast to adult ones.

Knockdown of Smox protects the integrity of the blood-brain barrier through antioxidant effect and Nrf2 pathway activation in stroke

Once an ischemic stroke occurs, reactive oxygen species (ROS) and oxidative stress degrade the tight connections between cerebral endothelial cells resulting in their damage. The expression of antioxidant genes may be enhanced, and ROS formation may be reduced following Nrf2 activation, which is associated with protection against ischemic stroke. Overexpression of spermine oxidase (Smox) in the neocortex led to increased H2O2 production. However, how Smox impacts the regulation of the blood–brain barrier (BBB) through antioxidants has not been examined yet. We conducted experiments both in the cell level and in the transient middle cerebral artery occlusion (tMCAO) model to evaluate the effect of Smox siRNA lentivirus (si-Smox) knockdown on BBB protection against ischemic stroke. Mice treated with si-Smox showed remarkably decreased BBB breakdown and reduced endothelial inflammation following stroke. The treatment with si-Smox significantly elevated the Bcl-2 to Bax ratio and decreased the production of cleaved caspase-3 in the tMCAO model. Further investigation revealed that the neuroprotective effect was the result of the antioxidant properties of si-Smox, which reduced oxidative stress and enhanced CD31+ cells in the peri-infarct cortical areas. Of significance, si-Smox activated Nrf2 in both bEnd.3 cells and tMCAO animals, and blocking Nrf2 with brusatol diminished the protective effects of si-Smox. The study findings suggest that si-Smox exerts neuroprotective effects and promotes angiogenesis by activating the Nrf2 pathway, thus decreasing oxidative stress and apoptosis caused by tMCAO. As a result, si-Smox may hold potential as a therapeutic candidate for preserving BBB integrity while treating ischemic stroke.

Abstract 16488: Sestrin2 Protects Against Long-Term Cardiac Injury and Remodeling by Modulating mTORC1 Activation in Myocardial Ischemia/Reperfusion

Introduction: Myocardial ischemia/reperfusion (I/R) injury can lead to long-term cardiac dysfunction and heart failure with reduced ejection fraction (HFrEF) in aged hearts. However, young hearts may exhibit some resistance to this process and retain better cardiac function. Our previous studies have identified a novel protein called Sestrin2 (Sesn2), which is downregulated in aged hearts. Hypothesis: Sesn2 may protect hearts from progressing to HFrEF following myocardial I/R. Methods: We induced myocardial I/R injury by ligation/release of the left anterior descending coronary arteries (LAD) in both C57BL/6J mice and mice with cardiac-specific Sesn2 knockout (Sesn2 cKO ). Cardiac function was assessed, and samples were collected at baseline, one day post I/R, seven days post I/R, and 28 days post I/R. Results: In wild-type (WT) hearts (12-18 weeks), cardiac function showed a slight decrease 28 days post I/R (IR28D), but the ejection fraction (EF) remained above 50%. However, Sesn2 cKO mice exhibited a significant reduction in cardiac function at IR28D, with an about 27.5% decrease in EF compared to WT hearts. We also observed a significant increase in volume at diastole in Sesn2 cKO mice at IR28D compared to their baseline and corresponding WT. Furthermore, when comparing mitochondrial respiration in the area at risk (AAR) of the left ventricles between the two groups, we found a significant decrease in oxygen consumption rate (OCR) and a significant increase in H 2 O 2 production in Sesn2 cKO hearts. Additionally, the mammalian target of rapamycin complex 1 (mTORC1) was significantly upregulated in Sesn2 cKO mice compared to WT hearts. Conclusions: Sesn2 exerts a cardiac protective effect by downregulating mTORC1 activation, thereby reducing long-term cardiac injury following I/R, attenuating cardiac remodeling, and improving mitochondrial respiration in the AAR of the heart.

Influencing factors and controlled release kinetics of H2O2 from PVP-coated calcium peroxide NPs for groundwater remediation

Calcium peroxide nanoparticles (nCP) as a versatile and safe solid source of hydrogen peroxide (H2O2) receive substantial attention from researchers as a potential groundwater remediation reagent. In this study, we synthesized polyvinylpyrrolidone-coated calcium peroxide nanoparticles (PVP@nCP-PVP) to control the release rate of H2O2 and modulate pH fluctuation simultaneously. The PVP@nCP-PVP is fully characterized and the H2O2 releasing kinetics and mechanisms are investigated. The H2O2 release longevity of nCP increased with the concentration of controlled release material (CRM) encapsulated shell, while the production of H2O2 decreased inversely. The acidic condition is favorable for increasing H2O2 production by promoting the complex decomposition of nCP. The low temperature prolonged the longevity of nCP and suppressed the competitive side reaction for producing O2. The release of H2O2 is consistent with zero-order reaction kinetics and the release of O2 is consistent with first-order reaction kinetics. At last, different nCP composites were employed to construct a Fenton-like system for the degradation of nitrobenzene (NB). The degradation rate was raised from 57.6% by Fe (II)/nCP to 70.0% and 93.7% by Fe (II)/nCP-PVP and Fe (II)/PVP@nCP-PVP systems, respectively. These findings demonstrate that PVP@nCP-PVP has significant advantages in repairing organically contaminated groundwater. Environmental implicationGroundwater contamination poses a great threat to human health and ecosystems. In-situ chemical oxidation (ISCO) is a widely used groundwater remediation technology. Calcium peroxide (CP) as solid hydrogen peroxide showed merits of low cost and high stability, but the further application was limited due to its violent chemical reaction and short longivity in groundwater . In this work, we prepared polyvinylpyrrolidone-coated controlled release nCP (PVP@nCP-PVP) for modulating the release of H2O2. The investigation of H2O2 release kinetics under various environmental conditions enhances the understanding of the inherent relationship between the H2O2 release performance of controlled-release materials and contamination remediation. The feasibility using macromolecules preparing controlled-release oxidizing agents was confirmed, providing a novel solution for groundwater contamination remediation.

Electrosynthesis of H2O2 over aerated cathode assembled by aligned titanium hollow fibers

Electrochemical two-electron oxygen reduction is an attractive in-situ H2O2 production technology. Herein, we developed a novel cathode mode to increase H2O2 production and practicality of electrochemical technology. In this mode, aligned titanium hollow fibers (TiHFs) work as an assembled aerated cathode. O2 enters through the axial microchannel and radial nanopores of TiHF to arrive at Ti-electrolyte interphase, resulting in unrestricted O2 supply and no flooding problem that plagues gas diffusion electrodes (GDEs). Using only four fibers as assembled aerated cathode, 79.3 mM H2O2 (∼0.27 wt%) was accumulated within 1 h, which was greater than most of reported values on GDEs and met the requirement of Fenton technology in wastewater treatment (0.1 wt%). Sequentially, the performance of this TiHF aerated cathode in organic degradation was confirmed via one-electron reduction of produced H2O2 to generate •OH. A long-term stability up to 60 h could be achieved for TiHF aerated cathode, which was superior to most previously reported GDEs for H2O2 electrosynthesis (typically, < 30 h). Furthermore, the working mechanism of H2O2 production is revealed via confocal laser scanning microscopy and in situ Raman. The dynamic formation-disappearance of the three-phase interface and the accumulation of reactive intermediate (such as *OOH) were responsible for high yield and good stability.

Visible light driven hydrogen peroxide production by oxygen and phosphorus co-doped CoP-C3N4 photocatalyst

Photocatalytic hydrogen peroxide (H2O2) by oxygen and phosphorus co-doped graphitic carbon nitride (C3N4) with cobalt phosphate (CoP) cocatalyst is investigated. The photocatalyst powder of CoP-C3N4 1:n, n = 0–4, n is the weight ratio of cyanuric acid added) was synthesized by melamine cyanurate template method. Characterization of the catalyst was performed by X-ray diffraction analysis, and scanning electron microscopy, X-ray photoemission spectra, and fluorescence decay spectra. Oxygen doping was performed by the melamine and cyanuric acid template method, followed by phosphorus doping of the C3N4 backbone by the introduction of CoP. Co-doping of O and P atom facilitated charge transfer on the C3N4 backbone, while CoP facilitated charge separation at the C3N4 interface. The CoP-C3N4 (1:4) photocatalyst increased H2O2 production rate by 293 % compared to that of the cyanuric acid-free photocatalyst and also achieved the photocatalytic oxygen evolution from water. These results indicate that O,P co-doped CoP-C3N4 can perform sacrificial agent-free hydrogen peroxide under visible light irradiation.

Downregulation of SODD mediates carnosol-induced reduction in cell proliferation in esophageal adenocarcinoma cells

Esophageal adenocarcinoma carries a poor prognosis associated with a 5-year survival rate of 12.5–20%. Therefore, a new therapeutic modality is needed for this lethal tumor. Carnosol is a phenolic diterpene purified from the herbs such as rosemary and Mountain desert sage and has been shown to have anticancer activities in multiple cancers. In this study we examined the effect of carnosol on cell proliferation in esophageal adenocarcinoma cells. We found that carnosol dose-dependently decreased cell proliferation in FLO-1 esophageal adenocarcinoma cells and significantly increased caspase-3 protein, indicating that carnosol decreases cell proliferation and increases cell apoptosis in FLO-1 cells. Carnosol significantly increased H2O2 production and N-acetyl cysteine, a reactive oxygen species (ROS) scavenger, significantly inhibited carnosol-induced decrease in cell proliferation, indicating that ROS may mediate carnosol-induced decrease in cell proliferation. Carnosol-induced decrease in cell proliferation was partially reversed by NADPH oxidase inhibitor apocynin, suggesting that NADPH oxidases may be partially involved in carnosol’s effect. In addition, carnosol significantly downregulated SODD protein and mRNA expression and knockdown of SODD significantly inhibited the carnosol-induced reduction in cell proliferation, suggesting that downregulation of SODD may contribute to carnosol-induced reduction in cell proliferation. We conclude that carnosol dose-dependently decreased cell proliferation and significantly increased caspase-3 protein. Carnosol’s effect may be through the overproduction of ROS and the downregulation of SODD. Carnosol might be useful for the treatment of esophageal adenocarcinoma.