Hydrogen peroxide sensing and signaling by protein kinases in the cardiovascular system

The application and prospects of drug delivery systems in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease primarily affecting elderly individuals aged >65 years and has a poor prognosis. No effective treatment is currently available for IPF. The two antipulmonary fibrosis drugs nintedanib and pirfenidone approved by the FDA in the United States have somewhat decelerated IPF progression. However, the side effects of these drugs can lead to poor patient tolerance and compliance with the medications. Researchers have recently developed various methods for IPF treatment, such as gene silencing and pathway inhibitors, which hold great promise in IPF treatment. Nevertheless, the nonselectivity and nonspecificity of drugs often affect their efficacies. Drug delivery systems (DDS) are crucial for delivering drugs to specific target tissues or cells, thereby minimizing potential side effects, enhancing drug bioavailability, and reducing lung deposition. This review comprehensively summarizes the current state of DDS and various delivery strategies for IPF treatment (e.g., nano-delivery, hydrogel delivery, and biological carrier delivery) to completely expound the delivery mechanisms of different drug delivery carriers. Subsequently, the advantages and disadvantages of different DDS are fully discussed. Finally, the challenges and difficulties associated with the use of different DDS are addressed so as to accelerate their rapid clinical translation.

Rational Design of Genetically Engineered Mitochondrial-Targeting Nanozymes for Alleviating Myocardial Ischemic-Reperfusion Injury

The development of mitochondria-targeting nanozymes holds significant promise for treating myocardial ischemia-reperfusion (IR) injury but faces significant biological barriers. To overcome these obstacles, we herein utilized genetically engineered ferritin nanocages (i.e., imFTn) to develop mitochondria-targeting nanozymes consisting of three ferritin subunit assembly modules: an IR-injured cardiomyocyte-targeting module, a lysosome-escaping module, and a mitochondria-targeting module. Using imFTn as a nanozyme platform, we developed nanozymes capable of efficiently catalyzing the l-Arg substrate to produce NO. The imFTn-Ru exhibits NO-generating activities, reduces mitochondrial reactive oxygen species generation, inhibits mitochondrial permeability transition pore opening, and enhances mitochondrial membrane potential. Furthermore, imFTn-Ru provides synergistic effects by specifically targeting myocardial IR-injured tissues, facilitating their accumulation in mitochondria, and protecting mitochondria against myocardial IR-induced injury in both in vitro and in vivo models. This study underscores a rational approach to designing nanozymes for targeting specific subcellular organelles in the treatment of IR injury.

A Closed-Loop Cascade Strategy for On-Demand Regulation of Uric Acid

Despite that the current anti-hyperuricemia drugs can effectively reduce uric acid (UA) levels, imprecise medication dosage or uncontrolled lowering of UA levels may result in undesired effects. To address this issue, a closed-loop cascade strategy based on a biocompatible network composite, NW-FPNP/uricase (UOX), is proposed for on-demand regulation of UA levels. NW-FPNP/UOX is constructed by encapsulation of UOX) as UA-responsive element and FPNP, a nanoparticle of phenylboronic acid modified xanthine oxidase (XOD) inhibitor febuxostat, as H2O2-sensitive element with AMP/Gd3+ network. It interrelates the UA metabolization and generation processes into a closed loop of cascade reactions involving UOX-catalyzed UA metabolization and H2O2 generation, H2O2-triggered febuxostat regeneration and XOD inhibition, and XOD-catalyzed UA generation. Through UA level-dependent auto-adjustment of XOD activity, specially 6% at 600 × 10-6 m UA compared to 82% at 100 × 10-6 m, UA levels can be regulated to an appropriate range through dynamically balancing UA metabolization and generation. This biocompatible on-demand UA regulation system prevents the overdose of UA-lowering medications and avoids hypouricemia in hyperuricemia treatment, demonstrating great potential in intelligent UA level management. This work also introduces a new concept of a closed-loop cascade strategy for on-demand regulation of biochemical indicators within specific thresholds.

pH/H2O2 dual-responsive macrophage-targeted chitosaccharides nanoparticles to combat intracellular bacterial infection

Antibiotic resistance combined with bacteria internalization result in recurrent infections that seriously threaten human health. To overcome these problems, a pH/H2O2 dual-responsive nanoparticle (COSBN@CFS@PS) that can target macrophages, exhibiting synergistic antibiotic and β-lactamase inhibitor activity, is reported. Chitosaccharides (COS) is covalently bound with benzenboronic acid pinacol ester and assemble with cefoxitin sodium salt (CFS) to form COSBN@CFS nanoparticles. Then, COSBN@CFS was encapsulated with phosphatidylserine (PS), which aimed to targeted uptake by macrophages. After the uptake, the pH/H2O2 dual-responsive nanoparticle could effectively inhibit β-lactamase activity by release boronic acid (β-lactamase inhibitor), and then reinforced the antibacterial activity of CFS. Meanwhile, the resultant nanoparticles could significantly inhibit the growth of CFS-resistant bacteria. Furthermore, these nanoparticles could eliminate intracellular bacteria in vivo through the synergistic activities of antibiotic and β-lactamase inhibitor. The excellent biocompatibility and outstanding bactericidal activity promise COSBN@CFS@PS have great potential for diverse intracellular bacterial infection therapy.

Microenvironment-responsive nanosystems for ischemic stroke therapy

Ischemic stroke, a common neurological disorder caused by impaired blood supply to the brain, presents a therapeutic challenge. Conventional treatments like thrombolysis and neuroprotection drugs lack ideal drug delivery systems, limiting their effectiveness. Selectively delivering therapies to the ischemic cerebral tissue holds great potential for preventing and/or treating ischemia-related pathological symptoms. The unique pathological microenvironment of the brain after ischemic stroke, characterized by hypoxia, acidity, and inflammation, offers new possibilities for targeted drug delivery. Pathological microenvironment-responsive nanosystems, extensively investigated in tumors with hypoxia-responsive systems as an example, could also respond to the ischemic cerebral microenvironment and achieve brain-targeted drug delivery and release. These emerging nanosystems are gaining traction for ischemic stroke treatment. In this review, we expound on the cerebral pathological microenvironment and clinical treatment strategies of ischemic stroke, highlight various stimulus-responsive materials employed in constructing ischemic stroke microenvironment-responsive nano delivery systems, and discuss the application of these microenvironment-responsive nanosystems in microenvironment regulation for ischemic stroke treatment.

Development and translation of thiometallate sulfide donors using a porcine model of coronary occlusion and reperfusion

Sulfide-releasing compounds reduce reperfusion injury by decreasing mitochondria-derived reactive oxygen species production. We previously characterised ammonium tetrathiomolybdate (ATTM), a clinically used copper chelator, as a sulfide donor in rodents. Here we assessed translation to large mammals prior to clinical testing. In healthy pigs an intravenous ATTM dose escalation revealed a reproducible pharmacokinetic/pharmacodynamic (PK/PD) relationship with minimal adverse clinical or biochemical events. In a myocardial infarction (1-h occlusion of the left anterior descending coronary artery)-reperfusion model, intravenous ATTM or saline was commenced just prior to reperfusion. ATTM protected the heart (24-h histological examination) in a drug-exposure-dependent manner (r2 = 0.58, p < 0.05). Blood troponin T levels were significantly (p < 0.05) lower in ATTM-treated animals while myocardial glutathione peroxidase activity, an antioxidant selenoprotein, was elevated (p < 0.05). Overall, our study represents a significant advance in the development of sulfides as therapeutics and underlines the potential of ATTM as a novel adjunct therapy for reperfusion injury. Mechanistically, our study suggests that modulating selenoprotein activity could represent an additional mode of action of sulfide-releasing drugs.

Pneumococcal hydrogen peroxide regulates host cell kinase activity

Introduction

Protein kinases are indispensable reversible molecular switches that adapt and control protein functions during cellular processes requiring rapid responses to internal and external events. Bacterial infections can affect kinase-mediated phosphorylation events, with consequences for both innate and adaptive immunity, through regulation of antigen presentation, pathogen recognition, cell invasiveness and phagocytosis. Streptococcus pneumoniae (Spn), a human respiratory tract pathogen and a major cause of community-acquired pneumoniae, affects phosphorylation-based signalling of several kinases, but the pneumococcal mediator(s) involved in this process remain elusive. In this study, we investigated the influence of pneumococcal H2O2 on the protein kinase activity of the human lung epithelial H441 cell line, a generally accepted model of alveolar epithelial cells.

Methods

We performed kinome analysis using PamGene microarray chips and protein analysis in Western blotting in H441 lung cells infected with Spn wild type (SpnWT) or with SpnΔlctOΔspxB -a deletion mutant strongly attenuated in H2O2 production- to assess the impact of pneumococcal hydrogen peroxide (H2O2) on global protein kinase activity profiles.

Results

Our kinome analysis provides direct evidence that kinase activity profiles in infected H441 cells significantly vary according to the levels of pneumococcal H2O2. A large number of kinases in H441 cells infected with SpnWT are significantly downregulated, whereas this no longer occurs in cells infected with the mutant SpnΔlctOΔspxB strain, which lacks H2O2. In particular, we describe for the first time H2O2-mediated downregulation of Protein kinase B (Akt1) and activation of lymphocyte-specific tyrosine protein kinase (Lck) via H2O2-mediated phosphorylation.

Intracellular infection-responsive macrophage-targeted nanoparticles for synergistic antibiotic immunotherapy of bacterial infection

Intracellular bacteria are considered to play a key role in the failure of bacterial infection therapy and increase of antibiotic resistance. Nanotechnology-based drug delivery carriers have been receiving increasing attention for improving the intracellular antibacterial activity of antibiotics, but are accompanied by disadvantages such as complex preparation procedures, lack of active targeting, and monotherapy, necessitating further design improvements. Herein, nanoparticles targeting bacteria-infected macrophages are fabricated to eliminate intracellular bacterial infections via antibiotic release and upregulation of intracellular reactive oxygen species (ROS) levels and proinflammatory responses. These nanoparticles were formed through the reaction of the amino group on selenocystamine dihydrochloride and the aldehyde group on oxidized dextran (ox-Dex), which encapsulates vancomycin (Van) through hydrophobic interactions. These nanoparticles could undergo targeted uptake by macrophages via endocytosis and respond to the bacteria-infected intracellular microenvironment (ROS and glutathione (GSH)) for controlled release of antibiotics. Furthermore, these nanoparticles could consume intracellular GSH and promote a significant increase in the level of ROS in macrophages, subsequently up-regulating the proinflammatory response to reinforce antibacterial activity. These nanoparticles can accelerate bacteria-infected wound healing. In this work, nanoparticles were fabricated for bacteria-infected macrophage-targeted and microenvironment-responsive antibiotic delivery, cellular ROS generation, and proinflammatory up-regulation activity to eliminate intracellular bacteria, which opens up a new possibility for multifunctional drug delivery against intracellular infection.

Cardiac monoamine oxidase-A inhibition protects against catecholamine-induced ventricular arrhythmias via enhanced diastolic calcium control

AIMS

A mechanistic link between depression and risk of arrhythmias could be attributed to altered catecholamine metabolism in the heart. Monoamine oxidase-A (MAO-A), a key enzyme involved in catecholamine metabolism and longstanding antidepressant target, is highly expressed in the myocardium. The present study aimed to elucidate the functional significance and underlying mechanisms of cardiac MAO-A in arrhythmogenesis.

METHODS AND RESULTS

Analysis of the TriNetX database revealed that depressed patients treated with MAO inhibitors had a lower risk of arrhythmias compared with those treated with selective serotonin reuptake inhibitors. This effect was phenocopied in mice with cardiomyocyte-specific MAO-A deficiency (cMAO-Adef), which showed a significant reduction in both incidence and duration of catecholamine stress-induced ventricular tachycardia compared with wild-type mice. Additionally, cMAO-Adef cardiomyocytes exhibited altered Ca2+ handling under catecholamine stimulation, with increased diastolic Ca2+ reuptake, reduced diastolic Ca2+ leak, and diminished systolic Ca2+ release. Mechanistically, cMAO-Adef hearts had reduced catecholamine levels under sympathetic stress, along with reduced levels of reactive oxygen species and protein carbonylation, leading to decreased oxidation of Type II PKA and CaMKII. These changes potentiated phospholamban (PLB) phosphorylation, thereby enhancing diastolic Ca2+ reuptake, while reducing ryanodine receptor 2 (RyR2) phosphorylation to decrease diastolic Ca2+ leak. Consequently, cMAO-Adef hearts exhibited lower diastolic Ca2+ levels and fewer arrhythmogenic Ca2+ waves during sympathetic overstimulation.

CONCLUSION

Cardiac MAO-A inhibition exerts an anti-arrhythmic effect by enhancing diastolic Ca2+ handling under catecholamine stress.

Oxidative Stress Promotes Liver Cancer Metastasis via RNF25-Mediated E-Cadherin Protein Degradation

Loss of E-cadherin (ECAD) is required in tumor metastasis. Protein degradation of ECAD in response to oxidative stress is found in metastasis of hepatocellular carcinoma (HCC) and is independent of transcriptional repression as usually known. Mechanistically, protein kinase A (PKA) senses oxidative stress by redox modification in its β catalytic subunit (PRKACB) at Cys200 and Cys344. The activation of PKA kinase activity subsequently induces RNF25 phosphorylation at Ser450 to initiate RNF25-catalyzed degradation of ECAD. Functionally, RNF25 repression induces ECAD protein expression and inhibits HCC metastasis in vitro and in vivo. Altogether, these results indicate that RNF25 is a critical regulator of ECAD protein turnover, and PKA is a necessary redox sensor to enable this process. This study provides some mechanistic insight into how oxidative stress-induced ECAD degradation promotes tumor metastasis of HCC.

AQP5 deficiency promotes the senescence of lens epithelial cells through mitochondrial dysfunction

Cataract is lens opacity, which is a common blinding eye disease worldwide. Aquaporin 5 (AQP5) is expressed in the human and mouse lenses. This study aimed to investigate the underlying mechanisms of AQP5 in the senescence of lens epithelial cells (LECs). Primary LECs were isolated and cultured from Aqp5+/+ and Aqp5-/- mice. Western blot or immunofluorescence staining of p16, Ki67, MitoSOX, JC-1 and phalloidin was used in the experiments to evaluate the changes in the primary LECs. The primary Aqp5-/- LECs showed increased p16 expression and mitochondrial reactive oxygen species, decreased mitochondrial membrane potential and activity, and cytoskeletal disorders. When the cells were pretreated with Mito-TEMPO, the Aqp5-/- mice showed decreased p16 expression, reduced mitochondrial dysfunction and cytoskeletal disorders. Our results revealed that AQP5 deficiency promotes the senescence of primary LECs through mitochondrial dysfunction. This provides a new perspective for the treatment of cataracts by regulating AQP5 expression.

Hydrogen peroxide-dependent oxidation of ERK2 within its D-recruitment site alters its substrate selection

Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are dysregulated in many pervasive diseases. Recently, we discovered that ERK1/2 is oxidized by signal-generated hydrogen peroxide in various cell types. Since the putative sites of oxidation lie within or near ERK1/2's ligand-binding surfaces, we investigated how oxidation of ERK2 regulates interactions with the model substrates Sub-D and Sub-F. These studies revealed that ERK2 undergoes sulfenylation at C159 on its D-recruitment site surface and that this modification modulates ERK2 activity differentially between substrates. Integrated biochemical, computational, and mutational analyses suggest a plausible mechanism for peroxide-dependent changes in ERK2-substrate interactions. Interestingly, oxidation decreased ERK2's affinity for some D-site ligands while increasing its affinity for others. Finally, oxidation by signal-generated peroxide enhanced ERK1/2's ability to phosphorylate ribosomal S6 kinase A1 (RSK1) in HeLa cells. Together, these studies lay the foundation for examining crosstalk between redox- and phosphorylation-dependent signaling at the level of kinase-substrate selection.

GYY4137, a hydrogen sulfide donor, protects against endothelial dysfunction in porcine coronary arteries exposed to myeloperoxidase and hypochlorous acid

BACKGROUND AND AIMS

Myeloperoxidase (MPO) and its principal reaction product hypochlorous acid (HOCl) are part of the innate immune response but are also associated with endothelial dysfunction, thought to involve a reduction in nitric oxide (NO) bioavailability. We aimed to investigate the effect of MPO and HOCl on vasorelaxation of coronary arteries and to assess directly the involvement of NO. In addition, we hypothesised that the slow release hydrogen sulfide (H2S) donor GYY4137 would salvage coronary artery endothelial function in the presence of MPO and HOCl.

METHODS AND RESULTS

Contractility of porcine coronary artery segments was measured using isometric tension recording. Incubation with MPO (50 ng/ml) plus hydrogen peroxide (H2O2) (30 μM; substrate for MPO) impaired endothelium-dependent vasorelaxation to bradykinin in coronary arteries. HOCl (10-500 μM) also impaired endothelium-dependent relaxations. There was no effect of MPO plus H2O2, or HOCl, on endothelium-independent relaxations to 5'-N-ethylcarboxamidoadenosine and sodium nitroprusside. L-NAME (300 μM), a NO synthase inhibitor, attenuated bradykinin relaxations, leaving L-NAME-resistant relaxations to bradykinin mediated by endothelium-dependent hyperpolarization. In the presence of L-NAME, MPO plus H2O2 largely failed to impair endothelium-dependent relaxations to bradykinin. Similarly, HOCl failed to inhibit endothelium-dependent relaxations to bradykinin in the presence of L-NAME. GYY4137 (1-100 μM) protected endothelium-dependent relaxations to bradykinin from dysfunction caused by MPO plus H2O2, and HOCl, with no effect alone on bradykinin relaxation responses. The specific MPO inhibitor aminobenzoic acid hydrazide (ABAH) (1 and 10 μM) also protected against MPO plus H2O2-induced endothelial dysfunction (at 10 μM ABAH), but was less potent than GYY4137.

CONCLUSIONS

MPO plus H2O2, and HOCl, impair coronary artery endothelium-dependent vasorelaxation via inhibition of NO. GYY4137 protects against endothelial dysfunction in arteries exposed to MPO plus H2O2, and HOCl. H2S donors such as GYY4137 are possible therapeutic options to control excessive MPO activity in cardiovascular diseases.

Increased nitric oxide availability worsens the cardiac performance during early re-perfusion period in adult rats

OBJECTIVES

Re-perfusion is the standard therapy for acute myocardial infarction, despite the associated pathologies that may contribute to irreversible myocardial injury. The present study aims to clarify the alterations in cardiac activities in response to experimental cardiac ischemic arrest followed by re-perfusion in isolated hearts perfused with nitric oxide (NO) donor, l-arginine, or NO inhibitor, Nω-Nitro-l-arginine methyl ester hydrochloride (l-NAME), to shed light on the possible role of NO in the re-perfusion process.

METHODS

Hearts isolated from adult Wistar rats were studied on Langendorff preparation under basal conditions and during 30 min re-perfusion following 30 min of total global ischemia. Rats were randomly divided into three groups; control and l-arginine or l-NAME infused heart groups. Cardiac tissue content of malondialdhyde, catalase and nitrite was also measured.

RESULTS

Compared to the control group, both l-arginine and l-NAME infused hearts showed increased basal chronotropy and myocardial flow rate. Following ischemia and during the whole period of re-perfusion, the three groups demonstrated significant deterioration in the inotropic activity and compromised myocardial flow rate. l-arginine infused hearts revealed depressed inotropy and chronotropy, weak systolic and diastolic functions with compromised myocardial flow at early 5 min of re-perfusion, yet with significantly higher myocardial flow rate by the end of re-perfusion.

CONCLUSIONS

Reducing NO availability by l-NAME revealed mild impact on the ischemia re-perfusion induced contractile dysfunction, whereas excess NO worsens cardiac performance at the early re-perfusion period.

Rethreading Design of Ratiometric roGFP2 Mimetic Peptide for Hydrogen Peroxide Sensing

Reconstruction of the miniaturized peptide to mimic the tailored functions of protein has been attractive but challenging. Herein, initialized from the crystal structure of redox-sensitive green fluorescent protein-2 (roGFP2), we propose a practical approach to construct the roGFP2 mimetic peptide by rethreading the aromatic residues adjacent to the chromophore fragment. By fine-tuning the residues of peptides, a mini tetrapeptide (Cys-Phe-Phe-His) was designed, which can act as a hydrogen peroxide sensor using its ratiometric fluorescence. The roGFP2 mimetic tetrapeptide is biocompatible and photostable and has competitive fluorescent properties with roGFP2 by the virtue of its assembly induced emissions. We expand the ratiometric tetrapeptide for sensing hydrogen peroxide in acidic chambers. The results provide a promising approach for the artificial design of miniaturized peptides with the desired function.

Exercise training rescues impaired H2O2-mediated vasodilation in porcine collateral-dependent coronary arterioles through enhanced K+ channel activation

We previously reported that exercise training drives enhanced agonist-stimulated hydrogen peroxide (H2O2) levels and restores endothelium-dependent dilation via an increased reliance on H2O2 in arterioles isolated from ischemic porcine hearts. In this study, we tested the hypothesis that exercise training would correct impaired H2O2-mediated dilation in coronary arterioles isolated from ischemic myocardium through increases in protein kinase G (PKG) and protein kinase A (PKA) activation and subsequent colocalization with sarcolemmal K+ channels. Female adult Yucatan miniature swine were surgically instrumented with an ameroid constrictor around the proximal left circumflex coronary artery, gradually inducing a collateral-dependent vascular bed. Arterioles (∼125 µm) supplied by the left anterior descending artery served as nonoccluded control vessels. Pigs were separated into exercise (treadmill; 5 days/wk for 14 wk) and sedentary groups. Collateral-dependent arterioles isolated from sedentary pigs were significantly less sensitive to H2O2-induced dilation compared with nonoccluded arterioles, whereas exercise training reversed the impaired sensitivity. Large conductance calcium-activated potassium (BKCa) channels and 4AP-sensitive voltage-gated (Kv) channels contributed significantly to dilation in nonoccluded and collateral-dependent arterioles of exercise-trained but not sedentary pigs. Exercise training significantly increased H2O2-stimulated colocalization of BKCa channels and PKA, but not PKG, in smooth muscle cells of collateral-dependent arterioles compared with other treatment groups. Taken together, our studies suggest that with exercise training, nonoccluded and collateral-dependent coronary arterioles better use H2O2 as a vasodilator through increased coupling with BKCa and 4AP-sensitive Kv channels; changes that are mediated in part by enhanced colocalization of PKA with BKCa channels.NEW & NOTEWORTHY The current study reveals that coronary arterioles distal to stenosis display attenuated dilation responses to H2O2 that are restored with endurance exercise training. Enhanced H2O2 dilation after exercise is dependent on Kv and BKCa channels and at least in part on in colocalization of BKCa channel and PKA and independent of PKA dimerization. These findings expand our earlier studies which demonstrated that exercise training drives beneficial adaptive responses of reactive oxygen species in the microvasculature of the ischemic heart.

ROS-Responsive Janus Au/Mesoporous Silica Core/Shell Nanoparticles for Drug Delivery and Long-Term CT Imaging Tracking of MSCs in Pulmonary Fibrosis Treatment

Mesenchymal stem cell (MSC) therapy has been proven to be a potentially effective approach for idiopathic pulmonary fibrosis (IPF) treatment. However, this strategy is currently limited by the poor curative effect and an insufficient comprehension of the in vivo condition of the transplanted MSCs in the remedy of IPF. To address these issues, herein, a nanosystem composed of Janus Au/mesoporous silica core/shell nanoparticles (Janus NPs) is designed for effective therapeutic and real-time tracing of MSCs in MSC-based IPF therapy. The Janus NPs consist of a Au core and a pirfenidone (PFD)-loaded mesoporous silica shell asymmetrically decorated with two targeting moieties: one is reactive oxygen species (ROS)-sensitive thioketal grafted methoxy poly(ethylene glycol) (mPEG-TK), and the other is 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE). The asymmetric decoration on each side of the particle allows long-term anchoring of the Janus NPs on the cell membrane to facilitate the responsive release of PFD in the ROS environment of the fibrotic lung, thereby enhancing the therapeutic efficacy of the transplanted MSCs by improving the microenvironment. Following drug release, the Janus NPs quickly enter into MSCs, achieving long-term computed tomography (CT) imaging tracing of MSCs in IPF model mice for an in-depth comprehension of the cell therapy mechanism. Overall, this work reports on Janus Au/PFD-loaded mesoporous silica core/shell NPs that combine the drug delivery and imaging tracking of MSCs, which may provide a strategy for the stem cell-based treatment of IPF.

Promoting gene transfection by ROS responsive silicon nanowire arrays

The development of a fast and safe reactive oxygen species (ROS)-responsive vector is generally limited by the intracellular unstable ROS concentration, and a relatively long time is still needed for the complete intracellular release of drugs or genes induced by ROS. In this work, a gene transfection platform based on ROS-responsive silicon nanowire arrays (SN) is developed, to promote the gene transfection efficiency for several cell lines. Briefly, the surface of the ROS generating system, gold nanoparticle modified SN (SN-Au), is grafted with poly[(2-acryloyl)ethyl(p-boronic acid benzyl)diethylammonium bromide] (B-PDEAEA), an oxidation-responsive charge-reversal cationic polymer. Plasmid DNA (pDNA) bound on the surface through electrostatic interactions was directly delivered into the cells by the time the nanowires penetrate the cells. SN-Au can generate ROS under light treatment, which has an influence on the surface charge change of B-PDEAEA grafted on gold nanoparticles, realizing effective pDNA release in the cytosol for transfection. Nearly 80% of DNA released from the surface of the platform after treated with 1 mM ROS for 10 min. The transfection efficiency of the platform for several cell types was significantly enhanced after a short period of light exposure (3.2-fold for HeLa cells, 7.6-fold for L929 cells, 2.3-fold for BMSC cells and 6.2-fold for mESC cells). The platform also has good biocompatibility. Overall, our results suggest that ROS-responsive SN is a novel, efficient and safe platform for drug and gene transfection.

Application of Fluorescent Probes in Reactive Oxygen Species Disease Model

Reactive oxygen species (ROS) play an important role in living activities as signaling molecules that regulate the living activities of organisms. There are many types of ROS, mainly including hydrogen peroxide (H2O2), hypochlorous acid (HOCl), hydroxyl radical (•OH), peroxyl radical (ROO•), singlet oxygen (1O2), peroxynitrite (ONOO-) and superoxide anion radical (O2-•) etc. Existing studies have shown that changes in ROS levels are closely associated with the development of many diseases, such as inflammation, cancer, cardiovascular disease, and neurodegenerative damage. Small molecule fluorescent probes have been widely used in biology, pathology and medical diagnosis due to their advantages of noninvasive, high sensitivity and in vivo real-time detection. It is extremely important to better apply small-molecule fluorescent probes to detect ROS levels in organisms to achieve early diagnosis of diseases and assessment of therapeutic conditions. This work focuses on summarizing the representative applications of some fluorescent probes in ROS disease models in recent years. This article focuses on summarizing the construction methods of various ROS-related disease models, and classifying and analyzing the basic ideas and methods of fluorescent probes applied to disease models according to the characteristics of various diseases.

An Injectable Dual-Function Hydrogel Protects Against Myocardial Ischemia/Reperfusion Injury by Modulating ROS/NO Disequilibrium

Acute myocardial infarction (MI) is the leading cause of death worldwide. Exogenous delivery of nitric oxide (NO) to the infarcted myocardium has proven to be an effective strategy for treating MI due to the multiple physiological functions of NO. However, reperfusion of blood flow to the ischemic tissues is accompanied by the overproduction of toxic reactive oxygen species (ROS), which can further exacerbate tissue damage and compromise the therapeutic efficacy. Here, an injectable hydrogel is synthesized from the chitosan modified by boronate-protected diazeniumdiolate (CS-B-NO) that can release NO in response to ROS stimulation and thereby modulate ROS/NO disequilibrium after ischemia/reperfusion (I/R) injury. Furthermore, administration of CS-B-NO efficiently attenuated cardiac damage and adverse cardiac remodeling, promoted repair of the heart, and ameliorated cardiac function, unlike a hydrogel that only released NO, in a mouse model of myocardial I/R injury. Mechanistically, regulation of the ROS/NO balance activated the antioxidant defense system and protected against oxidative stress induced by I/R injury via adaptive regulation of the Nrf2-Keap1 pathway. Inflammation is then reduced by inhibition of the activation of NF-κB signaling. Collectively, these results show that this dual-function hydrogel may be a promising candidate for the protection of tissues and organs after I/R injury.

SOD1 mediates lysosome-to-mitochondria communication and its dysregulation by amyloid-β oligomers

Altered mitochondrial DNA (mtDNA) occurs in neurodegenerative disorders like Alzheimer's disease (AD); how mtDNA synthesis is linked to neurodegeneration is poorly understood. We previously discovered Nutrient-induced Mitochondrial Activity (NiMA), an inter-organelle signaling pathway where nutrient-stimulated lysosomal mTORC1 activity regulates mtDNA replication in neurons by a mechanism sensitive to amyloid-β oligomers (AβOs), a primary factor in AD pathogenesis (Norambuena et al., 2018). Using 5-ethynyl-2'-deoxyuridine (EdU) incorporation into mtDNA of cultured neurons, along with photoacoustic and mitochondrial metabolic imaging of cultured neurons and mouse brains, we show these effects being mediated by mTORC1-catalyzed T40 phosphorylation of superoxide dismutase 1 (SOD1). Mechanistically, tau, another key factor in AD pathogenesis and other tauopathies, reduced the lysosomal content of the tuberous sclerosis complex (TSC), thereby increasing NiMA and suppressing SOD1 activity and mtDNA synthesis. AβOs inhibited these actions. Dysregulation of mtDNA synthesis was observed in fibroblasts derived from tuberous sclerosis (TS) patients, who lack functional TSC and elevated SOD1 activity was also observed in human AD brain. Together, these findings imply that tau and SOD1 couple nutrient availability to mtDNA replication, linking mitochondrial dysfunction to AD.

Mechanochemical synthesis of an AIE-TICT-ESIPT active orange-emissive chemodosimeter for selective detection of hydrogen peroxide in aqueous media and living cells, and solid-phase quantitation using a smartphone

We report herein the design and mechanochemical synthesis of a chemodosimeter, benzothiazole-derived unsymmetrical azine protected by 4-bromomethylphenylboronic acid (BTPAB), an orange aggregation-induced emission (AIE), for the selective detection of H2O2 in a turn-on manner.

Stimuli-responsive drug delivery systems for head and neck cancer therapy

Head and neck cancer (HNC) is among the most common malignancy that has a profound impact on human health and life quality. The treatment for HNC, especially for the advanced cancer is stage-dependent and in need of combined therapies. Various forms of adjuvant treatments such as chemotherapy, phototherapy, hyperthermia, gene therapy have been included in the HNC therapy. However, there are still restrictions with traditional administration such as limited in situ therapeutic effect, systemic toxicity, drug resistance, etc. In recent years, stimuli-responsive drug delivery systems (DDSs) have attracted the great attention in HNC therapy. These intelligent DDSs could respond to unique tumor microenvironment, external triggers or dual/multi stimulus with more specific drug delivery and release, leading to enhanced treatment efficiency and less reduced side effects. In this article, recent studies on stimuli-responsive DDSs for HNC therapy were summarized, which could respond to endogenous and exogenous triggers including pH, matrix metalloproteinases (MMPs), reactive oxygen species (ROS), redox condition, light, magnetic field and multi stimuli. Their therapeutic remarks, current limits and future prospect for these intelligent DDSs were discussed. Furthermore, multifunctional stimuli-responsive DDSs have also been reviewed. With the modification of drug carriers or co-loading with therapeutic agents. Those intelligent DDSs showed more biofunctions such as combined therapeutic effects or integration of diagnosis and treatment for HNC. It is believed that stimuli-responsive drug delivery systems showed great potential for future clinic translation and application for the treatment of HNC.

Prognostic impact of diabetes in chronic and acute heart failure

A strong, bidirectional relationship exists between diabetes mellitus (DM) and heart failure (HF) and DM is responsible of the activation of several molecular and pathophysiological mechanisms that may, on the long term, damage the heart. However, the prognostic role of DM in the context of chronic and acute HF is still not yet defined and there are several gaps of evidence in the literature on this topic. These gaps are related to the wide phenotypic heterogeneity of patients with chronic and acute HF and to the concept that not all diabetic patients are the same, but there is the necessity to better characterize the disease and each single patient, also considering the role of other possible comorbidities. The aim of the present review is to summarize the pathophysiological mechanisms subtending the negative effect of DM in HF and analyze the available data exploring the prognostic impact of such comorbidity in both chronic and acute HF.

Optimization of Nanostructured Copper Sulfide to Achieve Enhanced Enzyme-Mimic Activities for Improving Anti-Infection Performance

Advanced antibacterial methods are urgently needed to deal with possible infectious diseases. As promising alternatives to antibiotics, enzyme-mimic nanocatalysts face bottlenecks of low activities and indistinct catalytic mechanisms, which seriously restrict their development for anti-infection treatment. Herein, metastable copper sulfide (Cu_2-xS) nanozymes with diversiform sizes and compositions were selected to adjust the electronic structure for enhancing enzyme-mimic activities. The as-synthesized large and thin nanoplates (L/TN nanoplates), with the stoichiometric ratio of Cu_1.25S, were proven to possess the optimal peroxidase (POD)-mimic activity. Using quantum mechanics, it was theoretically revealed that the sulfur vacancies could alter the electronic structure of copper active sites and thus reduce the reaction energy barrier of H₂O₂ to·OH to promote the POD-mimic performance. Moreover, through enhanced enzyme-mimic activities, L/TN nanoplates achieved efficient depletion of glutathione and ascorbic acid for improving antibacterial performances. Further, synergizing with the NIR irradiation, the satisfactory destruction capability for bacteria and biofilm was achieved for L/TN nanoplates under an inflammatory level of hydrogen peroxide (50 μM). Altogether, this work provides a deeper understanding of geometrical and electronic properties-dependent antibacterial performance, and paves the way toward precise compositions and structures engineering of nanozymes.

Systematic Combination of Oligonucleotides and Synthetic Polymers for Advanced Therapeutic Applications

The potential of oligonucleotides is exceptional in therapeutics because of their high safety, potency, and specificity compared to conventional therapeutic agents. However, many obstacles, such as low in vivo stability and poor cellular uptake, have hampered their clinical success. Use of polymeric carriers can be an effective approach for overcoming the biological barriers and thereby maximizing the therapeutic efficacy of the oligonucleotides due to the availability of highly tunable synthesis and functional modification of various polymers. As loaded in the polymeric carriers, the therapeutic oligonucleotides, such as antisense oligonucleotides, small interfering RNAs, microRNAs, and even messenger RNAs, become nuclease-resistant by bypassing renal filtration and can be efficiently internalized into disease cells. In this review, we introduced a variety of systematic combinations between the therapeutic oligonucleotides and the synthetic polymers, including the uses of highly functionalized polymers responding to a wide range of endogenous and exogenous stimuli for spatiotemporal control of oligonucleotide release. We also presented intriguing characteristics of oligonucleotides suitable for targeted therapy and immunotherapy, which can be fully supported by versatile polymeric carriers.

The Interplay between S-Glutathionylation and Phosphorylation of Cardiac Troponin I and Myosin Binding Protein C in End-Stage Human Failing Hearts

Oxidative stress is defined as an imbalance between the antioxidant defense system and the production of reactive oxygen species (ROS). At low levels, ROS are involved in the regulation of redox signaling for cell protection. However, upon chronical increase in oxidative stress, cell damage occurs, due to protein, DNA and lipid oxidation. Here, we investigated the oxidative modifications of myofilament proteins, and their role in modulating cardiomyocyte function in end-stage human failing hearts. We found altered maximum Ca²⁺-activated tension and Ca²⁺ sensitivity of force production of skinned single cardiomyocytes in end-stage human failing hearts compared to non-failing hearts, which was corrected upon treatment with reduced glutathione enzyme. This was accompanied by the increased oxidation of troponin I and myosin binding protein C, and decreased levels of protein kinases A (PKA)- and C (PKC)-mediated phosphorylation of both proteins. The Ca²⁺ sensitivity and maximal tension correlated strongly with the myofilament oxidation levels, hypo-phosphorylation, and oxidative stress parameters that were measured in all the samples. Furthermore, we detected elevated titin-based myocardial stiffness in HF myocytes, which was reversed by PKA and reduced glutathione enzyme treatment. Finally, many oxidative stress and inflammation parameters were significantly elevated in failing hearts compared to non-failing hearts, and corrected upon treatment with the anti-oxidant GSH enzyme. Here, we provide evidence that the altered mechanical properties of failing human cardiomyocytes are partially due to phosphorylation, S-glutathionylation, and the interplay between the two post-translational modifications, which contribute to the development of heart failure.

Construction of a lysosome-targetable ratiometric fluorescent probe for H2O2 tracing and imaging in living cells and an inflamed model

Hydrogen peroxide (H₂O₂), an important reactive oxygen species (ROS) with unique destructive oxidation properties, can be produced in lysosomes to fight off pathogens. Although many fluorescent probes have been developed for the detection and imaging of H₂O₂, the development of a ratiometric fluorescent probe for H₂O₂ detection and imaging in lysosomes and an inflammation model remains rather scarce. Therefore, it is important to develop an efficient tool for monitoring H₂O₂ in inflamed tissues to evaluate the physiological and pathological relationship between inflammation and lysosomal H₂O₂. In this work, a new naphthalimide-based lysosome-targeting fluorescent probe (NPT-H₂O₂) for ratiometric detection and imaging was developed in vitro and in vivo. The probe exhibited two well-resolved emission peaks separated by 125 nm, rapid response (<40 s), and high selectivity and sensitivity toward H₂O₂, as well as low cytotoxicity in vitro. Inspired by prominent features of these results, we further successfully applied NPT-H₂O₂ for H₂O₂ imaging with a dual-channel in living cells, demonstrating that our probe NPT-H₂O₂ was targeted in the lysosomes. Finally, NPT-H₂O₂ was used for H₂O₂ detection in inflamed tissues and achieved satisfactory results. We predict that our probe can be used as a powerful tool to reveal the relationship between physiology and pathology of inflammation and lysosomal H₂O₂.

Hydrogen peroxide (H₂O₂), an important reactive oxygen species (ROS) with unique destructive oxidation properties, can be produced in lysosomes to fight off pathogens.

Oxygen sensing, mitochondrial biology and experimental therapeutics for pulmonary hypertension and cancer

The homeostatic oxygen sensing system (HOSS) optimizes systemic oxygen delivery. Specialized tissues utilize a conserved mitochondrial sensor, often involving NDUFS2 in complex I of the mitochondrial electron transport chain, as a site of pO₂-responsive production of reactive oxygen species (ROS). These ROS are converted to a diffusible signaling molecule, hydrogen peroxide (H₂O₂), by superoxide dismutase (SOD2). H₂O₂ exits the mitochondria and regulates ion channels and enzymes, altering plasma membrane potential, intracellular Ca²⁺ and Ca²⁺-sensitization and controlling acute, adaptive, responses to hypoxia that involve changes in ventilation, vascular tone and neurotransmitter release. Subversion of this O₂-sensing pathway creates a pseudohypoxic state that promotes disease progression in pulmonary arterial hypertension (PAH) and cancer. Pseudohypoxia is a state in which biochemical changes, normally associated with hypoxia, occur despite normal pO₂. Epigenetic silencing of SOD2 by DNA methylation alters H₂O₂ production, activating hypoxia-inducible factor 1α, thereby disrupting mitochondrial metabolism and dynamics, accelerating cell proliferation and inhibiting apoptosis. Other epigenetic mechanisms, including dysregulation of microRNAs (miR), increase pyruvate dehydrogenase kinase and pyruvate kinase muscle isoform 2 expression in both diseases, favoring uncoupled aerobic glycolysis. This Warburg metabolic shift also accelerates cell proliferation and impairs apoptosis. Disordered mitochondrial dynamics, usually increased mitotic fission and impaired fusion, promotes disease progression in PAH and cancer. Epigenetic upregulation of dynamin-related protein 1 (Drp1) and its binding partners, MiD49 and MiD51, contributes to the pathogenesis of PAH and cancer. Finally, dysregulation of intramitochondrial Ca²⁺, resulting from impaired mitochondrial calcium uniporter complex (MCUC) function, links abnormal mitochondrial metabolism and dynamics. MiR-mediated decreases in MCUC function reduce intramitochondrial Ca²⁺, promoting Warburg metabolism, whilst increasing cytosolic Ca²⁺, promoting fission. Epigenetically disordered mitochondrial O₂-sensing, metabolism, dynamics, and Ca²⁺ homeostasis offer new therapeutic targets for PAH and cancer. Promoting glucose oxidation, restoring the fission/fusion balance, and restoring mitochondrial calcium regulation are promising experimental therapeutic strategies.

Reactive strategy-based SERS determination of O2˙- generated from sunscreen

A novel surface-enhanced Raman scattering (SERS) nanoprobe based on a reactive strategy was designed for the first time to determine the concentration of superoxide anion radical (O2˙-) produced from titanium dioxide by a UV radiation process. A limit of detection (LOD) for O2˙- of 9.0 nmol L-1 could be attained.

Oxidation of Protein Kinase A Regulatory Subunit PKARIα Protects Against Myocardial Ischemia-Reperfusion Injury by Inhibiting Lysosomal-Triggered Calcium Release

BACKGROUND

Kinase oxidation is a critical signaling mechanism through which changes in the intracellular redox state alter cardiac function. In the myocardium, PKARIα (type-1 protein kinase A) can be reversibly oxidized, forming interprotein disulfide bonds in the holoenzyme complex. However, the effect of PKARIα disulfide formation on downstream signaling in the heart, particularly under states of oxidative stress such as ischemia and reperfusion (I/R), remains unexplored.

METHODS

Atrial tissue obtained from patients before and after cardiopulmonary bypass and reperfusion and left ventricular (LV) tissue from mice subjected to I/R or sham surgery were used to assess PKARIα disulfide formation by immunoblot. To determine the effect of disulfide formation on PKARIα catalytic activity and subcellular localization, live-cell fluorescence imaging and stimulated emission depletion super-resolution microscopy were performed in prkar1 knock-out mouse embryonic fibroblasts, neonatal myocytes, or adult LV myocytes isolated from "redox dead" (Cys17Ser) PKARIα knock-in mice and their wild-type littermates. Comparison of intracellular calcium dynamics between genotypes was assessed in fura2-loaded LV myocytes, whereas I/R-injury was assessed ex vivo.

RESULTS

In both humans and mice, myocardial PKARIα disulfide formation was found to be significantly increased (2-fold in humans, P=0.023; 2.4-fold in mice, P<0.001) in response to I/R in vivo. In mouse LV cardiomyocytes, disulfide-containing PKARIα was not found to impact catalytic activity, but instead led to enhanced AKAP (A-kinase anchoring protein) binding with preferential localization of the holoenzyme to the lysosome. Redox-dependent regulation of lysosomal two-pore channels by PKARIα was sufficient to prevent global calcium release from the sarcoplasmic reticulum in LV myocytes, without affecting intrinsic ryanodine receptor leak or phosphorylation. Absence of I/R-induced PKARIα disulfide formation in "redox dead" knock-in mouse hearts resulted in larger infarcts (2-fold, P<0.001) and a concomitant reduction in LV contractile recovery (1.6-fold, P<0.001), which was prevented by administering the lysosomal two-pore channel inhibitor Ned-19 at the time of reperfusion.

CONCLUSIONS

Disulfide modification targets PKARIα to the lysosome, where it acts as a gatekeeper for two-pore channel-mediated triggering of global calcium release. In the postischemic heart, this regulatory mechanism is critical for protection from extensive injury and offers a novel target for the design of cardioprotective therapeutics.

H2O2/HOCl-based fluorescent probes for dynamically monitoring pathophysiological processes

Serving as representative reactive oxygen species (ROS), H2O2 and HOCl play crucial roles in biological metabolism and intercellular oxidation-reduction dynamic equilibrium. The overexpression of H2O2/HOCl may cause a variety of diseases, such as acute and chronic inflammation, cancer and neurodegenerative disorders. A major question in H2O2/HOCl-based pathological diagnosis is knowing how H2O2/HOCl concentrations can be accurately regulated to initiate a diagnosis and subsequently guarantee therapeutic effects in the course of medical advances. Fluorescent probes, with their great spatial and temporal resolutions, have been used in diverse pathophysiological processes and developed rapidly in the last five years. We summarise in this review the optical properties of H2O2/HOCl-responsive fluorescent probes and focus on effective distribution and dynamic monitoring by using pathophysiological models.

Myeloperoxidase: A versatile mediator of endothelial dysfunction and therapeutic target during cardiovascular disease

Myeloperoxidase (MPO) is a prominent mammalian heme peroxidase and a fundamental component of the innate immune response against microbial pathogens. In recent times, MPO has received considerable attention as a key oxidative enzyme capable of impairing the bioactivity of nitric oxide (NO) and promoting endothelial dysfunction; a clinically relevant event that manifests throughout the development of inflammatory cardiovascular disease. Increasing evidence indicates that during cardiovascular disease, MPO is released intravascularly by activated leukocytes resulting in its transport and sequestration within the vascular endothelium. At this site, MPO catalyzes various oxidative reactions that are capable of promoting vascular inflammation and impairing NO bioactivity and endothelial function. In particular, MPO catalyzes the production of the potent oxidant hypochlorous acid (HOCl) and the catalytic consumption of NO via the enzyme's NO oxidase activity. An emerging paradigm is the ability of MPO to also influence endothelial function via non-catalytic, cytokine-like activities. In this review article we discuss the implications of our increasing knowledge of the versatility of MPO's actions as a mediator of cardiovascular disease and endothelial dysfunction for the development of new pharmacological agents capable of effectively combating MPO's pathogenic activities. More specifically, we will (i) discuss the various transport mechanisms by which MPO accumulates into the endothelium of inflamed or diseased arteries, (ii) detail the clinical and basic scientific evidence identifying MPO as a significant cause of endothelial dysfunction and cardiovascular disease, (iii) provide an up-to-date coverage on the different oxidative mechanisms by which MPO can impair endothelial function during cardiovascular disease including an evaluation of the contributions of MPO-catalyzed HOCl production and NO oxidation, and (iv) outline the novel non-enzymatic mechanisms of MPO and their potential contribution to endothelial dysfunction. Finally, we deliver a detailed appraisal of the different pharmacological strategies available for targeting the catalytic and non-catalytic modes-of-action of MPO in order to protect against endothelial dysfunction in cardiovascular disease.

Coronary microvascular dysfunction in stable ischaemic heart disease (non-obstructive coronary artery disease and obstructive coronary artery disease)

Diffuse and focal epicardial coronary disease and coronary microvascular abnormalities may exist side-by-side. Identifying the contributions of each of these three players in the coronary circulation is a difficult task. Yet identifying coronary microvascular dysfunction (CMD) as an additional player in patients with coronary artery disease (CAD) may provide explanations of why symptoms may persist frequently following and why global coronary flow reserve may be more prognostically important than fractional flow reserve measured in a single vessel before percutaneous coronary intervention. This review focuses on the challenges of identifying the presence of CMD in the context of diffuse non-obstructive CAD and obstructive CAD. Furthermore, it is going to discuss the pathophysiology in this complex situation, examine the clinical context in which the interaction of the three components of disease takes place and finally look at non-invasive diagnostic methods relevant for addressing this question.

Vasoconstrictor Mechanisms in Chronic Hypoxia-Induced Pulmonary Hypertension: Role of Oxidant Signaling

Elevated resistance of pulmonary circulation after chronic hypoxia exposure leads to pulmonary hypertension. Contributing to this pathological process is enhanced pulmonary vasoconstriction through both calcium-dependent and calcium sensitization mechanisms. Reactive oxygen species (ROS), as a result of increased enzymatic production and/or decreased scavenging, participate in augmentation of pulmonary arterial constriction by potentiating calcium influx as well as activation of myofilament sensitization, therefore mediating the development of pulmonary hypertension. Here, we review the effects of chronic hypoxia on sources of ROS within the pulmonary vasculature including NADPH oxidases, mitochondria, uncoupled endothelial nitric oxide synthase, xanthine oxidase, monoamine oxidases and dysfunctional superoxide dismutases. We also summarize the ROS-induced functional alterations of various Ca2+ and K+ channels involved in regulating Ca2+ influx, and of Rho kinase that is responsible for myofilament Ca2+ sensitivity. A variety of antioxidants have been shown to have beneficial therapeutic effects in animal models of pulmonary hypertension, supporting the role of ROS in the development of pulmonary hypertension. A better understanding of the mechanisms by which ROS enhance vasoconstriction will be useful in evaluating the efficacy of antioxidants for the treatment of pulmonary hypertension.

Iodine Redistribution During Trauma, Sepsis, and Hibernation: An Evolutionarily Conserved Response to Severe Stress

OBJECTIVE

We performed these studies to learn how iodine in the form of free iodide behaves during stress.

DESIGN

Prospective observational trial using samples obtained from human trauma patients and retrospective observational study using remnant samples from human sepsis patients and arctic ground squirrels. Preclinical interventional study using hind-limb ischemia and reperfusion injury in mice.

SETTING

Level I trauma center emergency room and ICU and animal research laboratories.

SUBJECTS

Adult human sepsis and trauma patients, wild-caught adult arctic ground squirrels, and sexually mature laboratory mice.

INTERVENTIONS

Ischemia and reperfusion injury was induced in mice by temporary application of tourniquet to one hind-limb. Iodide was administered IV just prior to reperfusion.

MEASUREMENTS AND MAIN RESULTS

Free iodide was measured using ion chromatography. Relative to iodide in plasma from normal donors, iodide was increased 17-fold in plasma from trauma patients and 26-fold in plasma from sepsis patients. In arctic ground squirrels, iodide increases over three-fold during hibernation. And during ischemia/reperfusion injury in mice, iodide accumulates in ischemic tissue and reduces both local and systemic tissue damage.

CONCLUSIONS

Iodide redistributes during stress and improves outcome after injury. Essential functions of iodide may have contributed to its evolutionary selection and be useful as a therapeutic intervention for human patients.

Biomedical Application of Reactive Oxygen Species-Responsive Nanocarriers in Cancer, Inflammation, and Neurodegenerative Diseases

Numerous pathological conditions, including cancer, inflammatory diseases, and neurodegenerative diseases, are accompanied by overproduction of reactive oxygen species (ROS). This makes ROS vital flagging molecules in disease pathology. ROS-responsive drug delivery platforms have been developed. Nanotechnology has been broadly applied in the field of biomedicine leading to the progress of ROS-responsive nanoparticles. In this review, we focused on the production and physiological/pathophysiological impact of ROS. Particular emphasis is put on the mechanisms and effects of abnormal ROS levels on oxidative stress diseases, including cancer, inflammatory disease, and neurodegenerative diseases. Finally, we summarized the potential biomedical applications of ROS-responsive nanocarriers in these oxidative stress diseases. We provide insights that will help in the designing of new ROS-responsive nanocarriers for various applications.

Synthesis and characterization of a hyaluronic acid-based hydrogel with antioxidative and thermosensitive properties

Peripheral arterial disease (PAD) is initiated by progressive atherosclerotic blockages of the arteries supplying the lower extremities. The most common presentation of PAD is claudication (leg pain and severe walking limitation), with many patients progressing to limb threatening ischemia and amputation. Biomaterial approaches are just beginning to be explored in the therapy of PAD with different materials now being evaluated for the delivery of cells or growth factors in animal models of PAD. A biomaterial matrix optimized for minimally invasive injection in the ischemic leg muscles of patients with PAD is urgently needed. There are several important requirements for optimal delivery, retention, and performance of a biomaterial matrix in the mechanically, histologically, and biochemically dynamic intramuscular environment of the PAD leg. Ideally, the material should have mechanical properties matching those of the recipient muscle, undergo minimal swelling, and should introduce properties that can ameliorate the mechanisms operating in PAD like oxidative stress and damage. Here we have developed an injectable, antioxidative, and thermosensitive hydrogel system based on hyaluronic acid (HA). We first synthesized a unique crosslinker of disulfide-modified poloxamer F127 diacrylate. This crosslinker led to the creation of a thermosensitive HA hydrogel with minimal swelling and muscle-matching mechanical properties. We introduced unique disulfide groups into hydrogels which functioned as an effective reactive oxygen species scavenger, exhibited hydrogen peroxide (H2O2)-responsive degradation, and protected cells against H2O2-induced damage. Our antioxidative thermosensitive HA hydrogel system holds great potential for the treatment of the ischemic legs of patients with PAD.

Aurora A regulation by reversible cysteine oxidation reveals evolutionarily conserved redox control of Ser/Thr protein kinase activity

Reactive oxygen species (ROS) are physiological mediators of cellular signaling and play potentially damaging roles in human diseases. In this study, we found that the catalytic activity of the Ser/Thr kinase Aurora A was inhibited by the oxidation of a conserved cysteine residue (Cys290) that lies adjacent to Thr288, a critical phosphorylation site in the activation segment. Cys is present at the equivalent position in ~100 human Ser/Thr kinases, a residue that we found was important not only for the activity of human Aurora A but also for that of fission yeast MAPK-activated kinase (Srk1) and PKA (Pka1). Moreover, the presence of this conserved Cys predicted biochemical redox sensitivity among a cohort of human CAMK, AGC, and AGC-like kinases. Thus, we predict that redox modulation of the conserved Cys290 of Aurora A may be an underappreciated regulatory mechanism that is widespread in eukaryotic Ser/Thr kinases. Given the key biological roles of these enzymes, these findings have implications for understanding physiological and pathological responses to ROS and highlight the importance of protein kinase regulation through multivalent modification of the activation segment.

Redox signaling modulates Rho activity and tissue contractility in the Caenorhabditis elegans spermatheca

Actomyosin-based contractility in smooth muscle and nonmuscle cells is regulated by signaling through the small GTPase Rho and by calcium-activated pathways. We use the myoepithelial cells of the Caenorhabditis elegans spermatheca to study the mechanisms of coordinated myosin activation in vivo. Here, we show that redox signaling modulates RHO-1/Rho activity in this contractile tissue. Exogenously added as well as endogenously generated hydrogen peroxide decreases spermathecal contractility by inhibition of RHO-1, which depends on a conserved cysteine in its nucleotide binding site (C20). Further, we identify an endogenous gradient of H₂O₂ across the spermathecal tissue, which depends on the activity of cytosolic superoxide dismutase, SOD-1. Collectively, we show that SOD-1-mediated H₂O₂ production regulates the redox environment and fine tunes Rho activity across the spermatheca through oxidation of RHO-1 C20.

Absorbable Thioether Grafted Hyaluronic Acid Nanofibrous Hydrogel for Synergistic Modulation of Inflammation Microenvironment to Accelerate Chronic Diabetic Wound Healing

Current standard of care dressings are unsatisfactorily inefficacious for the treatment of chronic wounds. Chronic inflammation is the primary cause of the long-term incurable nature of chronic wounds. Herein, an absorbable nanofibrous hydrogel is developed for synergistic modulation of the inflammation microenvironment to accelerate chronic diabetic wound healing. The electrospun thioether grafted hyaluronic acid nanofibers (FHHA-S/Fe) are able to form a nanofibrous hydrogel in situ on the wound bed. This hydrogel degrades and is absorbed gradually within 3 days. The grafted thioethers on HHA can scavenge the reactive oxygen species quickly in the early inflammation phase to relieve the inflammation reactions. Additionally, the HHA itself is able to promote the transformation of the gathered M1 macrophages to the M2 phenotype, thus synergistically accelerating the wound healing phase transition from inflammation to proliferation and remodeling. On the chronic diabetic wound model, the average remaining wound area after FHHA-S/Fe treatment is much smaller than both that of FHHA/Fe without grafted thioethers and the control group, especially in the early wound healing stage. Therefore, this facile dressing strategy with intrinsic dual modulation mechanisms of the wound inflammation microenvironment may act as an effective and safe treatment strategy for chronic wound management.

The role of mitochondrial reactive oxygen species, NO and H2 S in ischaemia/reperfusion injury and cardioprotection

Redox signalling in mitochondria plays an important role in myocardial ischaemia/reperfusion (I/R) injury and in cardioprotection. Reactive oxygen and nitrogen species (ROS/RNS) modify cellular structures and functions by means of covalent changes in proteins including among others S‐nitros(yl)ation by nitric oxide (NO) and its derivatives, and S‐sulphydration by hydrogen sulphide (H₂S). Many enzymes are involved in the mitochondrial formation and handling of ROS, NO and H₂S under physiological and pathological conditions. In particular, the balance between formation and removal of reactive species is impaired during I/R favouring their accumulation. Therefore, various interventions aimed at decreasing mitochondrial ROS accumulation have been developed and have shown cardioprotective effects in experimental settings. However, ROS, NO and H₂S play also a role in endogenous cardioprotection, as in the case of ischaemic pre‐conditioning, so that preventing their increase might hamper self‐defence mechanisms. The aim of the present review was to provide a critical analysis of formation and role of reactive species, NO and H₂S in mitochondria, with a special emphasis on mechanisms of injury and protection that determine the fate of hearts subjected to I/R. The elucidation of the signalling pathways of ROS, NO and H₂S is likely to reveal novel molecular targets for cardioprotection that could be modulated by pharmacological agents to prevent I/R injury.

Reactive oxygen species in cardiovascular health and disease: special references to nitric oxide, hydrogen peroxide, and Rho-kinase

The interaction between endothelial cells and vascular smooth muscle cells (VSMC) plays an important role in regulating cardiovascular homeostasis. Endothelial cells synthesize and release endothelium-derived relaxing factors (EDRFs), including vasodilator prostaglandins, nitric oxide (NO), and endothelium-dependent hyperpolarization (EDH) factors. Importantly, the contribution of EDRFs to endothelium-dependent vasodilatation markedly varies in a vessel size-dependent manner; NO mainly mediates vasodilatation of relatively large vessels, while EDH factors in small resistance vessels. We have previously identified that endothelium-derived hydrogen peroxide (H₂O₂) is an EDH factor especially in microcirculation. Several lines of evidence indicate the importance of the physiological balance between NO and H₂O₂/EDH factor. Rho-kinase was identified as the effectors of the small GTP-binding protein, RhoA. Both endothelial NO production and NO-mediated signaling in VSMC are targets and effectors of the RhoA/Rho-kinase pathway. In endothelial cells, the RhoA/Rho-kinase pathway negatively regulates NO production. On the contrary, the pathway enhances VSMC contraction with resultant occurrence of coronary artery spasm and promotes the development of oxidative stress and vascular remodeling. In this review, I will briefly summarize the current knowledge on the regulatory roles of endothelium-derived relaxing factors, with special references to NO and H₂O₂/EDH factor, in relation to Rho-kinase, in cardiovascular health and disease.

Activation of the NF-κB and MAPK Signaling Pathways Contributes to the Inflammatory Responses, but Not Cell Injury, in IPEC-1 Cells Challenged with Hydrogen Peroxide

Oxidative stress can lead to intestinal cell injury as well as the induction of inflammation. It is not clear whether inflammation is an important factor leading to cell injury caused by oxidative stress. The purpose of this study was to investigate the role of inflammation in intestinal injury caused by hydrogen peroxide (H₂O₂). Our results revealed that H₂O₂ stimulation significantly decreased the viability of intestinal porcine epithelial cells (IPEC-1), increased lactate dehydrogenase (LDH) activity, and disrupted the distribution of the tight junction protein claudin-1. H₂O₂ significantly increased the mRNA expression of interleukin-6 (IL-6), IL-8, and tumor necrosis factor-α (TNF-α). H₂O₂ stimulation also led to increased phosphorylation of p38 and jun N-terminal kinase (JNK), and p65 NF-κB protein translocation into the nucleus of IPEC-1 cells. Cells treated with the NF-κB inhibitor (BAY11-7082), the p38 inhibitor (SB202190), or the JNK inhibitor (PD98059) significantly decreased mRNA and protein expression of IL-6, IL-8, and TNF-α. However, treatment with mitogen-activated protein kinase (MAPK) or NF-κB inhibitors did not prevent the damage effect on cell viability, LDH activity, or the distribution of claudin-1 in cells challenged with H₂O₂. In summary, our data demonstrate that activation of the NF-κB and MAPK signaling pathways can contribute to the inflammatory response, but not cell injury, in IPEC-1 cells challenged with H₂O₂.