Hydrogen sulfide decreases the levels of ROS by inhibiting mitochondrial complex IV and increasing SOD activities in cardiomyocytes under ischemia/reperfusion

Thrombosis and Aging: Fibrin Clot Properties and Oxidative Stress

Significance: Aging is a complex process associated with an increased risk of many diseases, including thrombosis. This review summarizes age-related prothrombotic mechanisms in clinical settings of thromboembolism, focusing on the role of fibrin structure and function modified by oxidative stress. Recent Advances: Aging affects blood coagulation and fibrinolysis via multiple mechanisms, including enhanced oxidative stress, with an imbalance in the oxidant/antioxidant mechanisms, leading to loss of function and accumulation of oxidized proteins, including fibrinogen. Age-related prothrombotic alterations are multifactorial involving enhanced platelet activation, endothelial dysfunction, and changes in coagulation factors and inhibitors. Formation of more compact fibrin clot networks displaying impaired susceptibility to fibrinolysis represents a novel mechanism, which might contribute to atherothrombosis and venous thrombosis. Alterations to fibrin clot structure/function are at least in part modulated by post-translational modifications of fibrinogen and other proteins involved in thrombus formation, with a major impact of carbonylation. Fibrin clot properties are also involved in the efficacy and safety of therapy with oral anticoagulants, statins, and/or aspirin. Critical Issues: Since a prothrombotic state is observed in very elderly individuals free of diseases associated with thromboembolism, the actual role of activated blood coagulation in health remains elusive. It is unclear to what extent oxidative modifications of coagulation and fibrinolytic proteins, in particular fibrinogen, contribute to a prothrombotic state in healthy aging. Future Directions: Ongoing studies will show whether novel therapies that may alter oxidative stress and fibrin characteristics are beneficial to prevent atherosclerosis and thromboembolic events associated with aging.

Therapeutic Potential of Hydrogen Sulfide in Ischemia and Reperfusion Injury

Ischemia-reperfusion (I/R) injury, a prevalent pathological condition in medical practice, presents significant treatment challenges. Hydrogen sulfide (H2S), acknowledged as the third gas signaling molecule, profoundly impacts various physiological and pathophysiological processes. Extensive research has demonstrated that H2S can mitigate I/R damage across multiple organs and tissues. This review investigates the protective effects of H2S in preventing I/R damage in the heart, brain, liver, kidney, intestines, lungs, stomach, spinal cord, testes, eyes, and other tissues. H2S provides protection against I/R damage by alleviating inflammation and endoplasmic reticulum stress; inhibiting apoptosis, oxidative stress, and mitochondrial autophagy and dysfunction; and regulating microRNAs. Significant advancements in understanding the mechanisms by which H2S reduces I/R damage have led to the development and synthesis of H2S-releasing agents such as diallyl trisulfide-loaded mesoporous silica nanoparticles (DATS-MSN), AP39, zofenopril, and ATB-344, offering a new therapeutic avenue for I/R injury.

Benzylic Trifluoromethyl Accelerates 1,6-Elimination Toward Rapid Probe Activation

Activity-based detection of hydrogen sulfide in live cells can expand our understanding of its reactivity and complex physiological effects. We have discovered a highly efficient method for fluorescent probe activation, which is driven by H2S-triggered 1,6-elimination of an α-CF3-benzyl to release resorufin. In detecting intracellular H2S, 4-azido-(α-CF3)-benzyl resorufin offers significantly faster signal generation and improved sensitivity compared to 4-azidobenzyl resorufin. Computed free energy profiles for the 1,6-elimination process support the hypothesis that a benzylic CF3 group can reduce the activation energy barrier toward probe activation. This novel probe design allows for near-real-time detection of H2S in HeLa cells under stimulation conditions.

Biomimetic Vesicles with Designer Phospholipids Can Sense Environmental Redox Cues

Cell-like materials that sense environmental cues can serve as next-generation biosensors and help advance the understanding of intercellular communication. Currently, bottom-up engineering of protocell models from molecular building blocks remains a grand challenge chemists face. Herein, we describe giant unilamellar vesicles (GUVs) with biomimetic lipid membranes capable of sensing environmental redox cues. The GUVs employ activity-based sensing through designer phospholipids that are fluorescently activated in response to specific reductive (hydrogen sulfide) or oxidative (hydrogen peroxide) conditions. These synthetic phospholipids are derived from 1,2-dipalmitoyl-rac-glycero-3-phosphocholine and they possess a headgroup with heterocyclic aromatic motifs. Despite their structural deviation from the phosphocholine headgroup, the designer phospholipids (0.5-1.0 mol %) mixed with natural lipids can vesiculate, and the resulting GUVs (7-20 μm in diameter) remain intact over the course of redox sensing. All-atom molecular dynamics simulations gave insight into how these lipids are positioned within the hydrophobic core of the membrane bilayer and at the membrane-water interface. This work provides a purely chemical method to investigate potential redox signaling and opens up new design opportunities for soft materials that mimic protocells.

Manganese induces oxidative damage in the hippocampus by regulating the expression of oxidative stress-related genes via modulation of H3K18 acetylation

Prolonged exposure to manganese (Mn) contributes to hippocampal Mn accumulation, which leads to neurodegenerative diseases called manganese poisoning. However, the underlying molecular mechanisms remain unclear and there are no ideal biomarkers. Oxidative stress is the essential mechanisms of Mn-related neurotoxicity. Furthermore, histone acetylation has been identified as being engaged in the onset and development of neurodegenerative diseases. Therefore, the work aims to understand the molecular mechanisms of oxidative damage in the hippocampus due to Mn exposure from the aspect of histone acetylation modification and to assess whether H3K18 acetylation (H3K18ac) modification level in peripheral blood reflect Mn-induced oxidative damage in the hippocampus. Here, we randomly divided 60 male rats into four groups and injected them intraperitoneally with sterile pure water and MnCl2 ⋅4H2 O (5, 10, and 15 mg/kg) for 16 weeks, 5 days a week, once a day. The data confirmed that Mn exposure down-regulated superoxide dismutase activity and glutathione level as well as up-regulated malondialdehyde level in the hippocampus and plasma, and that there was a positive correlation between these indicators in the hippocampus and plasma. Besides, we noted that Mn treatment upregulated H3K18ac modification levels in the hippocampus and peripheral blood and that H3K18ac modification levels correlated with oxidative stress. Further studies demonstrated that Mn treatment decreased the amounts of H3K18ac enrichment in the manganese superoxide dismutase (SOD2) and glutathione transferase omega 1 (GSTO1) gene promoter regions, contributing to oxidative damage in the hippocampus. In short, our results demonstrate that Mn induces oxidative damage in the hippocampus by inhibiting the expression of SOD2 and GSTO1 genes via modulation of H3K18ac. In assessing Mn-induced hippocampal neurotoxicity, oxidative damage in plasma may reflect hippocampal oxidative damage in Mn-exposed groups.

Novel ray of hope for diabetic wound healing: Hydrogen sulfide and its releasing agents

BACKGROUND

Diabetes mellitus (DM) is a long-term metabolic disease accompanied by difficulties in wound healing placing a severe financial and physical burden on patients. As one of the important signal transduction molecules, both endogenous and exogenous hydrogen sulfide (H2S) was found to promote diabetic wound healing in recent studies. H2S at physiological concentrations can not only promote cell migration and adhesion functions, but also resist inflammation, oxidative stress and inappropriate remodeling of the extracellular matrix.

AIM OF REVIEW

The purpose of this review is to summarize current research on the function of H2S in diabetic wound healing at all stages, and propose future directions.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, first, the various factors affecting wound healing under diabetic pathological conditions and the in vivo H2S generation pathway are briefly introduced. Second, how H2S may improve diabetic wound healing is categorized and described. Finally, we discuss the relevant H2S donors and new dosage forms, analyze and reveal the characteristics of many typical H2S donors, which may provide new ideas for the development of H2S-released agents to improve diabetic wound healing.

Hydrogen sulfide responsive nanoplatforms: Novel gas responsive drug delivery carriers for biomedical applications

Hydrogen sulfide (H2S) is a toxic, essential gas used in various biological and physical processes and has been the subject of many targeted studies on its role as a new gas transmitter. These studies have mainly focused on the production and pharmacological side effects caused by H2S. Therefore, effective strategies to remove H2S has become a key research topic. Furthermore, the development of novel nanoplatforms has provided new tools for the targeted removal of H2S. This paper was performed to review the association between H2S and disease, related H2S inhibitory drugs, as well as H2S responsive nanoplatforms (HRNs). This review first analyzed the role of H2S in multiple tissues and conditions. Second, common drugs used to eliminate H2S, as well as their potential for combination with anticancer agents, were summarized. Not only the existing studies on HRNs, but also the inhibition H2S combined with different therapeutic methods were both sorted out in this review. Furthermore, this review provided in-depth analysis of the potential of HRNs about treatment or detection in detail. Finally, potential challenges of HRNs were proposed. This study demonstrates the excellent potential of HRNs for biomedical applications.

Cardioprotective Effects of Hydrogen Sulfide and Its Potential Therapeutic Implications in the Amelioration of Duchenne Muscular Dystrophy Cardiomyopathy

Hydrogen sulfide (H2S) belongs to the family of gasotransmitters and can modulate a myriad of biological signaling pathways. Among others, its cardioprotective effects, through antioxidant, anti-inflammatory, anti-fibrotic, and proangiogenic activities, are well-documented in experimental studies. Cardiorespiratory failure, predominantly cardiomyopathy, is a life-threatening complication that is the number one cause of death in patients with Duchenne muscular dystrophy (DMD). Although recent data suggest the role of H2S in ameliorating muscle wasting in murine and Caenorhabditis elegans models of DMD, possible cardioprotective effects have not yet been addressed. In this review, we summarize the current understanding of the role of H2S in animal models of cardiac dysfunctions and cardiac cells. We highlight that DMD may be amenable to H2S supplementation, and we suggest H2S as a possible factor regulating DMD-associated cardiomyopathy.

Dual-targeted nanoparticles with removing ROS inside and outside mitochondria for acute kidney injury treatment

Mitochondrial oxidative stress and inflammation are the main pathological features of acute kidney injury (AKI). However, systemic toxicity of anti-inflammatory drugs and low bioavailability of antioxidants limit the treatment of AKI. Here, the lipid micelle nanosystem modified with l-serine was designed to improve treatment of AKI. The micelle kernels coating the antioxidant drug 4-carboxybutyl triphenylph-osphine bromide-modified curcumin (Cur-TPP) and quercetin (Que). In the cisplatin (CDDP)-induced AKI model, the nanosystem protected mitochondrial structure and improved renal function. Compared to mono-targeted group, the mitochondrial ROS content of renal tubular epithelial cells acting in the dual-target group decreased about 1.66-fold in vitro, serum creatinine (Scr) and urea nitrogen (BUN) levels were reduced by 1.5 and 1.2 mmol/L in vivo, respectively. Mechanistic studies indicated that the nanosystem inhibited the inflammatory response by interfering with the NF-κB and Nrf2 pathways. This study provides an efficient and low-toxicity strategy for AKI therapy.

A Small-Molecule Approach to Bypass In Vitro Selection of New Aptamers: Designer Pre-Ligands Turn Baby Spinach into Sensors for Reactive Inorganic Targets

Fluorescent light-up aptamer (FLAP) systems are promising biosensing platforms that can be genetically encoded. Here, we describe how a single FLAP that works with specific organic ligands can detect multiple, structurally unique, non-fluorogenic, and reactive inorganic targets. We developed 4-O-functionalized benzylidene imidazolinones as pre-ligands with suppressed fluorescent binding interactions with the RNA aptamer Baby Spinach. Inorganic targets, hydrogen sulfide (H2S) or hydrogen peroxide (H2O2), can specifically convert these pre-ligands into the native benzylidene imidazolinones, and thus be detected with Baby Spinach. Adaptation of this approach to live cells opened a new opportunity for top-down construction of whole-cell sensors: Escherichia coli transformed with a Baby Spinach-encoding plasmid and incubated with pre-ligands generated fluorescence in response to exogenous H2S or H2O2. Our approach eliminates the requirement of in vitro selection of a new aptamer sequence for molecular target detection, allows for the detection of short-lived targets, thereby advancing FLAP systems beyond their current capabilities. Leveraging the functional group reactivity of small molecules can lead to cell-based sensors for inorganic molecular targets, exploiting a new synergism between synthetic organic chemistry and synthetic biology.

Persulfidation of mitoKv7.4 channels contributes to the cardioprotective effects of the H2S-donor Erucin against ischemia/reperfusion injury

BACKGROUND

Hydrogen sulfide (H2S) is a gasotransmitter deeply involved in cardiovascular homeostasis and implicated in the myocardial protection against ischemia/reperfusion. The post-translational persulfidation of cysteine residues has been identified as the mechanism through which H2S regulates a plethora of biological targets. Erucin (ERU) is an isothiocyanate produced upon hydrolysis of the glucosinolate glucoerucin, presents in edible plants of Brassicaceae family, such as Eruca sativa Mill., and it has emerged as a slow and long-lasting H2S-donor.

AIM

In this study the cardioprotective profile of ERU has been investigated and the action mechanism explored, focusing on the possible role of the recently identified mitochondrial Kv7.4 (mitoKv7.4) potassium channels.

RESULTS

Interestingly, ERU showed to release H2S and concentration-dependently protected H9c2 cells against H2O2-induced oxidative damage. Moreover, in in vivo model of myocardial infarct ERU showed protective effects, reducing the extension of ischemic area, the levels of troponin I and increasing the amount of total AnxA1, as well as co-related inflammatory outcomes. Conversely, the pre-treatment with XE991, a blocker of Kv7.4 channels, abolished them. In isolated cardiac mitochondria ERU exhibited the typical profile of a mitochondrial potassium channels opener, in particular, this isothiocyanate produced a mild depolarization of mitochondrial membrane potential, a reduction of calcium accumulation into the matrix and finally a flow of potassium ions. Finally, mitoKv7.4 channels were persulfidated in ERU-treated mitochondria.

CONCLUSIONS

ERU modulates the cardiac mitoKv7.4 channels and this mechanism may be relevant for cardioprotective effects.

Regulation of Mitochondrial Respiration by Hydrogen Sulfide

Hydrogen sulfide (H2S), the third gasotransmitter, has positive roles in animals and plants. Mitochondria are the source and the target of H2S and the regulatory hub in metabolism, stress, and disease. Mitochondrial bioenergetics is a vital process that produces ATP and provides energy to support the physiological and biochemical processes. H2S regulates mitochondrial bioenergetic functions and mitochondrial oxidative phosphorylation. The article summarizes the recent knowledge of the chemical and biological characteristics, the mitochondrial biosynthesis of H2S, and the regulatory effects of H2S on the tricarboxylic acid cycle and the mitochondrial respiratory chain complexes. The roles of H2S on the tricarboxylic acid cycle and mitochondrial respiratory complexes in mammals have been widely studied. The biological function of H2S is now a hot topic in plants. Mitochondria are also vital organelles regulating plant processes. The regulation of H2S in plant mitochondrial functions is gaining more and more attention. This paper mainly summarizes the current knowledge on the regulatory effects of H2S on the tricarboxylic acid cycle (TCA) and the mitochondrial respiratory chain. A study of the roles of H2S in mitochondrial respiration in plants to elucidate the botanical function of H2S in plants would be highly desirable.

Effect of Apremilast on LPS-induced immunomodulation and inflammation via activation of Nrf2/HO-1 pathways in rat lungs

Lipopolysaccharides (LPS), the lipid component of gram-negative bacterial cell wall, is recognized as the key factor in acute lung inflammation and is found to exhibit severe immunologic reactions. Phosphodiesterase-4 (PDE-4) inhibitor: "apremilast (AP)" is an immune suppressant and anti-inflammatory drug which introduced to treat psoriatic arthritis. The contemporary experiment designed to study the protective influences of AP against LPS induced lung injury in rodents. Twenty-four (24) male experimental Wistar rats selected, acclimatized, and administered with normal saline, LPS, or AP + LPS respectively from 1 to 4 groups. The lung tissues were evaluated for biochemical parameters (MPO), Enzyme Linked Immunosorbent Assay (ELISA), flowcytometry assay, gene expressions, proteins expression and histopathological examination. AP ameliorates the lung injuries by attenuating immunomodulation and inflammation. LPS exposure upregulated IL-6, TNF-α, and MPO while downregulating IL-4 which were restored in AP pretreated rats. The changes in immunomodulation markers by LPS were reduced by AP treatment. Furthermore, results from the qPCR analysis represented an upregulation in IL-1β, MPO, TNF-α, and p38 whereas downregulated in IL-10 and p53 gene expressions in disease control animals while AP pretreated rats exhibited significant reversal in these expressions. Western blot analysis suggested an upregulation of MCP-1, and NOS-2, whereas HO-1, and Nrf-2 expression were suppressed in LPS exposed animals, while pretreatment with AP showed down regulation in the expression MCP-1, NOS-2, and upregulation of HO-1, and Nrf-2 expression of the mentioned intracellular proteins. Histological studies further affirmed the toxic influences of LPS on the pulmonary tissues. It is concluded that, LPS exposure causes pulmonary toxicities via up regulation of oxidative stress, inflammatory cytokines and stimulation of IL-1β, MPO, TNF-α, p38, MCP-1, and NOS-2 while downregulation of IL-4, IL-10, p53, HO-1, and Nrf-2 at different expression level. Pretreatment with AP controlled the toxic influences of LPS by modulating these signaling pathways.

From Gasotransmitter to Immunomodulator: The Emerging Role of Hydrogen Sulfide in Macrophage Biology

Hydrogen sulfide (H₂S) has been increasingly recognized as a crucial inflammatory mediator in immune cells, particularly macrophages, due to its direct and indirect effects on cellular signaling, redox homeostasis, and energy metabolism. The intricate regulation of endogenous H₂S production and metabolism involves the coordination of transsulfuration pathway (TSP) enzymes and sulfide oxidizing enzymes, with TSP's role at the intersection of the methionine pathway and glutathione synthesis reactions. Additionally, H₂S oxidation mediated by sulfide quinone oxidoreductase (SQR) in mammalian cells may partially control cellular concentrations of this gasotransmitter to induce signaling. H₂S is hypothesized to signal through the posttranslational modification known as persulfidation, with recent research highlighting the significance of reactive polysulfides, a derivative of sulfide metabolism. Overall, sulfides have been identified as having promising therapeutic potential to alleviate proinflammatory macrophage phenotypes, which are linked to the exacerbation of disease outcomes in various inflammatory conditions. H₂S is now acknowledged to have a significant influence on cellular energy metabolism by affecting the redox environment, gene expression, and transcription factor activity, resulting in changes to both mitochondrial and cytosolic energy metabolism processes. This review covers recent discoveries pertaining to the involvement of H₂S in macrophage cellular energy metabolism and redox regulation, and the potential implications for the inflammatory response of these cells in the broader framework of inflammatory diseases.

Relationship Between ACSL4-Mediated Ferroptosis and Chronic Obstructive Pulmonary Disease

Purpose

Although cigarette smoke exposure is the major risk factor for chronic obstructive pulmonary disease (COPD), the mechanism is not completely understood. The aim of the present study was to investigate whether ACSL4-mediated ferroptosis in lung epithelial cells plays a part in the COPD development process and its association.

Patients and Methods

In this study, animal and cell models of COPD were modelled using cigarette smoke extracts (CSEs), and cell viability, lipid ROS, iron ion deposition, and ferroptosis-related markers were measured in lung tissue and lung epithelial cells following CSE exposure. Morphological changes in mitochondria were observed in lung tissue and epithelial cells of the lung by transmission electron microscope. The expression levels of ACSL4 mRNA and protein in lung tissue and epithelial cells were measured by real-time PCR and Western blotting. In addition, animal-interfering lentivirus and cell-interfering RNA against ACSL4 were constructed in this study, ferroptosis in lung tissue and lung epithelial cells after ACSL4 interference was detected, and ACSL4 mRNA and protein expression levels were detected.

Results

CSE induced ferroptosis in lung tissues and lung epithelial cells, and the expression levels of ACSL4 were elevated in CSE-treated lung tissues and lung epithelial cells. After ACSL4 interference, the expression of ACSL4 decreased, mitochondrial morphology was restored, and ferroptosis in lung tissues and lung epithelial cells was alleviated. Both respiratory frequency and enhanced pause of COPD mice models decreased after ACSL4 interference.

Conclusion

ACSL4-mediated ferroptosis in lung epithelial cells is associated with COPD and positively correlated with ferroptosis in epithelial cells.

H2S contributed from CSE during cellular senescence suppresses inflammation and nitrosative stress

Aging involves the time-dependent deterioration of physiological functions attributed to various intracellular and extracellular factors. Cellular senescence is akin to aging and involves alteration in redox homeostasis. This is primarily marked by increased reactive oxygen/nitrogen species (ROS/RNS), inflammatory gene expression, and senescence-associated beta-galactosidase activity, all hallmarks of aging. It is proposed that gasotransmitters which include hydrogen sulfide (H₂S), carbon monoxide (CO), and nitric oxide (NO), may affect redox homeostasis during senescence. H₂S has been independently shown to induce DNA damage and suppress oxidative stress. While an increase in NO levels during aging is well established, the role of H₂S has remained controversial. To understand the role of H₂S during aging, we evaluated H₂S homeostasis in non-senescent and senescent cells, using a combination of direct measurements with a fluorescent reporter dye (WSP-5) and protein sulfhydration analysis. The free intracellular H₂S and total protein sulfhydration levels are high during senescence, concomitant to cystathionine gamma-lyase (CSE) expression induction. Using lentiviral shRNA-mediated expression knockdown, we identified that H₂S contributed by CSE alters global gene expression, which regulates key inflammatory processes during cellular senescence. We propose that H₂S decreases inflammation during cellular senescence by reducing phosphorylation of IκBα and the p65 subunit of nuclear factor kappa B (NF-κB). H₂S was also found to reduce NO levels, a significant source of nitrosative stress during cellular senescence. Overall, we establish H₂S as a key gasotransmitter molecule that regulates inflammatory phenotype and nitrosative stress during cellular senescence.

Interactions of reactive sulfur species with metalloproteins

Reactive sulfur species (RSS) entail a diverse family of sulfur derivatives that have emerged as important effector molecules in H₂S-mediated biological events. RSS (including H₂S) can exert their biological roles via widespread interactions with metalloproteins. Metalloproteins are essential components along the metabolic route of oxygen in the body, from the transport and storage of O₂, through cellular respiration, to the maintenance of redox homeostasis by elimination of reactive oxygen species (ROS). Moreover, heme peroxidases contribute to immune defense by killing pathogens using oxygen-derived H₂O₂ as a precursor for stronger oxidants. Coordination and redox reactions with metal centers are primary means of RSS to alter fundamental cellular functions. In addition to RSS-mediated metalloprotein functions, the reduction of high-valent metal centers by RSS results in radical formation and opens the way for subsequent per- and polysulfide formation, which may have implications in cellular protection against oxidative stress and in redox signaling. Furthermore, recent findings pointed out the potential role of RSS as substrates for mitochondrial energy production and their cytoprotective capacity, with the involvement of metalloproteins. The current review summarizes the interactions of RSS with protein metal centers and their biological implications with special emphasis on mechanistic aspects, sulfide-mediated signaling, and pathophysiological consequences. A deeper understanding of the biological actions of reactive sulfur species on a molecular level is primordial in H₂S-related drug development and the advancement of redox medicine.

The Mycotoxin Patulin Inhibits the Mitochondrial Carnitine/Acylcarnitine Carrier (SLC25A20) by Interaction with Cys136 Implications for Human Health

The effect of mycotoxin patulin (4-hydroxy-4H-furo [3,2c] pyran-2 [6H] -one) on the mitochondrial carnitine/acylcarnitine carrier (CAC, SLC25A20) was investigated. Transport function was measured as [³H]-carnitine_ex/carnitine_in antiport in proteoliposomes reconstituted with the native protein extracted from rat liver mitochondria or with the recombinant CAC over-expressed in E. coli. Patulin (PAT) inhibited both the mitochondrial native and recombinant transporters. The inhibition was not reversed by physiological and sulfhydryl-reducing reagents, such as glutathione (GSH) or dithioerythritol (DTE). The IC₅₀ derived from the dose-response analysis indicated that PAT inhibition was in the range of 50 µM both on the native and on rat and human recombinant protein. The kinetics process revealed a competitive type of inhibition. A substrate protection experiment confirmed that the interaction of PAT with the protein occurred within a protein region, including the substrate-binding area. The mechanism of inhibition was identified using the site-directed mutagenesis of CAC. No inhibition was observed on Cys mutants in which only the C136 residue was mutated. Mass spectrometry studies and in silico molecular modeling analysis corroborated the outcomes derived from the biochemical assays.

Bibliometric evaluation of 2011-2021 publications on hydrogen sulfide in heart preservation research

Background

Hydrogen sulfide (H₂S) is known for its unpleasant odor and severe toxicity. However, an in-depth study of H₂S showed that it can be used as an important messenger, which can play important physiological and pathological roles in vitro and in vivo. In recent years, the application of H₂S in the field of cardiac preservation has attracted the interest and attention of scholars worldwide. H₂S plays an effective and protective role in cardiac ischemia/reperfusion injury through antioxidant, anti-inflammatory, and antiapoptotic mechanisms.

Objective

The purpose of this study is to analyze the current scientific achievements on the application of H₂S in the field of cardiac preservation and to provide new ideas for further research.

Methods

TS = ("hydrogen sulfide" OR "hydrogen sulfide") AND TS = ("cardiac" OR "heart" OR "myocardium" OR "hearts") AND TS = ("reperfusion" or "transplantation" or "implanted" or "transplant" or "implantation" or "migration" or "preservation" or "grafting" OR "ischemia" OR "perfusion" or "conservation" or "preserve" or "reservation") AND DT = (Article OR Review) AND LA = (English) were used as search strategies for data collection from the Science Citation Index-Expanded database of the Web of Science Core Collection. CiteSpace 5.8. R3 and Microsoft Office Excel 2019 were used for data analysis.

Results

A total of 429 related articles were included, and the total number of articles showed a fluctuating upward trend. We used CiteSpace 5.8. R3 and Microsoft Excel 2019 to evaluate and visualize the results, analyzing institutions, countries, journals, authors, co-cited references, and keywords.

Conclusions

As increasing evidence shows that H₂S plays an indispensable role in the field of cardiac preservation, its mechanistic research and clinical application may become the main focus of future research.

Cystathionine γ-lyase and hydrogen sulfide modulates glucose transporter Glut1 expression via NF-κB and PI3k/Akt in macrophages during inflammation

Macrophages play a crucial role in inflammation, a defense mechanism of the innate immune system. Metabolic function powered by glucose transporter isoform 1 (Glut1) is necessary for macrophage activity during inflammation. The present study investigated the roles of cystathionine-γ-lyase (CSE) and its byproduct, hydrogen sulfide (H2S), in macrophage glucose metabolism to explore the mechanism by which H2S acts as an inflammatory regulator in lipopolysaccharide- (LPS) induced macrophages. Our results demonstrated that LPS-treated macrophages increased Glut1 expression. LPS-induced Glut1 expression is regulated via nuclear factor (NF)-κB activation and is associated with phosphatidylinositol-3-kinase PI3k activation. Small interfering (si) RNA-mediated silencing of CSE decreased the LPS-induced NF-κB activation and Glut1 expression, suggesting a role for H2S in metabolic function in macrophages during pro-inflammatory response. Confoundingly, treatment with GYY4137, an H2S-donor molecule, also displayed inhibitory effects upon LPS-induced NF-κB activation and Glut1 expression. Moreover, GYY4137 treatment increased Akt activation, suggesting a role in promoting resolution of inflammation. Our study provides evidence that the source of H2S, either endogenous (via CSE) or exogenous (via GYY4137), supports or inhibits the LPS-induced NF-κB activity and Glut1 expression, respectively. Therefore, H2S may influence metabolic programming in immune cells to alter glucose substrate availability that impacts the immune response.

Kidney-Targeted Nanoparticles Loaded with the Natural Antioxidant Rosmarinic Acid for Acute Kidney Injury Treatment

Acute kidney injury (AKI) is a common clinical disease with high morbidity and mortality, and with a lack of effective drugs for treatment. Oxidative stress is very important in the occurrence and progression of AKI, and antioxidants use is one of the promising treatments. Rosmarinic acid (RA) is a ubiquitous natural polyphenol with powerful antioxidant and anti-inflammatory activities. Due to its inherent characteristic with poor water solubility and inferior bioavailability, its clinical application is impeded. Hence, the authors design a nanoparticle for effectively delivering RA, which is a chemical complex of RA and fourth-generation poly-amidoamine-based amphiphilic polymer (G4-PAMAM). The nanoparticle is modified with l-serine due to the specific interaction between kidney injury molecule-1 (Kim-1) and serine, which eventually generates a promising AKI kidney-targeting nanoparticle (S-G-R). The S-G-R is rapidly cumulated and long-term retained in ischemia-reperfusion-induced AKI kidneys, especially in the damaged renal tubular cells. The S-G-R exhibits more excellent antioxidative and antiapoptotic effects in vitro and has a more outstanding ability to improve the renal function, repair damaged renal tissue, and decrease oxidative stress, inflammatory response and apoptosis of tubular cells in vivo. Overall, this study might develop a safe and effective targeting strategy for the therapy of AKI.

Beta-Sitosterol Modulates the Migration of Vascular Smooth Muscle Cells via the PPARG/AMPK/mTOR Pathway

INTRODUCTION

The increased migration of vascular smooth muscle cells (VSMCs) is an essential pathological factor in the early development of atherosclerosis. Beta-sitosterol (BS), a natural phytosterol abundant in plant seeds, exhibits various bioactivities, including cardioprotective effects. However, its effects on VSMC migration and underlying mechanisms remain to be explored.

METHOD AND RESULT

BS inhibited the proliferation and migration of angiotensin II-induced A7r5 cells and reduced intracellular oxidative stress. Targets related to VSMC migration and the targets of BS were screened, cross-referenced, and analyzed by network pharmacology combined with molecular docking technology. The identified targets were verified at the protein and gene levels using Western blotting and quantitative PCR, respectively. BS was observed to activate peroxisome proliferator-activated receptor-γ (PPARG) and adenosine 5'-monophosphate-activated protein kinase (AMPK) and negatively regulate mammalian target of rapamycin (mTOR) expression. Furthermore, a PPARG inhibitor reversed the BS-induced activation of AMPK and mTOR.

CONCLUSION

This study indicated that regulation of the PPARG/AMPK/mTOR signaling pathway could potentially contribute to the inhibitory effects of BS on angiotensin II-induced VSMC migration.

Mitochondria-targeted hydrogen sulfide donors versus acute oxidative gastric mucosal injury

Hydrogen sulfide (H₂S) as a gaseous molecule prevents gastrointestinal (GI)-tract against various injuries. This study aimed to evaluate for the first time the detailed molecular mechanism of mitochondria-targeting H₂S-prodrugs, AP39 and RT01 in gastroprotection against ischemia/reperfusion (I/R)-induced lesions. Wistar rats exposed to I/R were pretreated i.g. with vehicle, AP39 (0.004-2 mg/kg), RT01 (0.1 mg/kg), or with AP219 (0.1 mg/kg) as structural control without ability to release H₂S. AP39 was also administered with mTOR1 inhibitor, rapamycin (1 mg/kg i.g.). Gastric damage area was assessed micro-/macroscopically, gastric blood flow (GBF) by laser flowmetry, mRNA level of HIF-1α, GPx, SOD1, SOD2, annexin-A1, SOCS3, IL-1RA, IL-1β, IL-1R1, IL-1R2, TNFR2, iNOS by real-time PCR. Gastric mucosal and/or serum content of IL-1β, IL-4, IL-5, IL-10, G-CSF, M-CSF, VEGFA, GRO, RANTES, MIP-1α, MCP1, TNF-α, TIMP1, FABP3, GST-α, STAT3/5 and phosphorylation of mTOR, NF-κB, ERK, Akt was evaluated by microbeads-fluorescent assay. Mitochondrial complexes activities were measured biochemically. RNA damage was assessed as 8-OHG by ELISA. AP39 and RT01 reduced micro-/macroscopic gastric I/R-injury increasing GBF. AP39-gastroprotection was accompanied by maintained activity of mitochondrial complexes, prevented RNA oxidation and enhanced mRNA/protein expression of SOCS3, IL-1RA, annexin-A1, GST-α, HIF-1α. Rapamycin reversed AP-39-gastroprotection. AP39-gastroprotection was followed by decreased NF-κB, ERK, IL-1β and enhanced Akt and mTOR proteins phosphorylation. AP39-prevented gastric mucosal damage caused by I/R-injury, partly by mitochondrial complex activity maintenance. AP39-mediated attenuation of gastric mucosal oxidation, hypoxia and inflammation involved mTOR1 and Akt pathways activity and modulation of HIF-1α, GST-α, SOCS3, IL1RA and TIMP1 molecular interplay.

Physiological roles of hydrogen sulfide in mammalian cells, tissues and organs

H2S belongs to the class of molecules known as gasotransmitters, which also includes nitric oxide (NO) and carbon monoxide (CO). Three enzymes are recognized as endogenous sources of H2S in various cells and tissues: cystathionine g-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). The current article reviews the regulation of these enzymes as well as the pathways of their enzymatic and non-enzymatic degradation and elimination. The multiple interactions of H2S with other labile endogenous molecules (e.g. NO) and reactive oxygen species are also outlined. The various biological targets and signaling pathways are discussed, with special reference to H2S and oxidative posttranscriptional modification of proteins, the effect of H2S on channels and intracellular second messenger pathways, the regulation of gene transcription and translation and the regulation of cellular bioenergetics and metabolism. The pharmacological and molecular tools currently available to study H2S physiology are also reviewed, including their utility and limitations. In subsequent sections, the role of H2S in the regulation of various physiological and cellular functions is reviewed. The physiological role of H2S in various cell types and organ systems are overviewed. Finally, the role of H2S in the regulation of various organ functions is discussed as well as the characteristic bell-shaped biphasic effects of H2S. In addition, key pathophysiological aspects, debated areas, and future research and translational areas are identified A wide array of significant roles of H2S in the physiological regulation of all organ functions emerges from this review.

The effect of manganese and iron on mediating resuscitation of lactic acid-injured Escherichia coli

Lactic acid can induce sublethal injury of E. coli through oxidative stress. In this study, we investigated changes in SOD activity, CAT activity, GSH production and ROS production during sublethal injury and resuscitation of E. coli. Then, the effect of manganese and iron during resuscitation were studied. Both cations (≥1 mmol l^-1 ) significantly promoted the resuscitation of sublethally injured E. coli induced by lactic acid and shortened the repair time (P < 0·05). Conversely, addition of N,N,N',N'-tetrakis (2-pyridylmethyl) which is a metal chelator extended the repair time. Compared with minA, manganese and iron significantly improved SOD activity at 40, 80 and 120 min and decreased ROS production at 40 and 80 min, thereby recovering injured E. coli quickly (P < 0·05). The deletion of sodA encoding Mn-SOD, sodB encoding Fe-SOD or gshA/gshB encoding GSH significantly strengthened sublethal injury and extended the repair time (P < 0·05). It meant these genes-related oxidative stress played important roles in the acid resistance of E. coli and recovery of sublethal injury. Therefore, manganese and iron can promote the recovery of lactic-injured E. coli by the way of increasing SOD activity, scavenging ROS, and relieving oxidative stress.

Signaling Integration of Hydrogen Sulfide and Iron on Cellular Functions

Significance: Hydrogen sulfide (H₂S) is an endogenous signaling molecule, regulating numerous physiological functions from vasorelaxation to neuromodulation. Iron is a well-known bioactive metal ion, being the central component of hemoglobin for oxygen transportation and participating in biomolecule degradation, redox balance, and enzymatic actions. The interplay between H₂S and iron metabolisms and functions impacts significantly on the fate and wellness of different types of cells. Recent Advances: Iron level in vivo affects the production of H₂S via nonenzymatic reactions. On the contrary, H₂S quenches excessive iron inside the cells and regulates the redox status of iron. Critical Issues: Abnormal metabolisms of both iron and H₂S are associated with various conditions and diseases such as iron overload, anemia, oxidative stress, and cardiovascular and neurodegenerative diseases. The molecular mechanisms for the interactions between H₂S and iron are unsettled yet. Here we review signaling links of the production, metabolism, and their respective and integrative functions of H₂S and iron in normalcy and diseases. Future Directions: Physiological and pathophysiological importance of H₂S and iron as well as their therapeutic applications should be evaluated jointly, not separately. Future investigation should expand from iron-rich cells and tissues to the others, in which H₂S and iron interaction has not received due attention. Antioxid. Redox Signal. 36, 275-293.

Rationale and Design of the Groningen Intervention Study for the Preservation of Cardiac Function with Sodium Thiosulfate after St-segment Elevation Myocardial Infarction (GIPS-IV) trial

BACKGROUND

Ischemia and subsequent reperfusion cause myocardial injury in patients presenting with ST-segment elevation myocardial infarction (STEMI). Hydrogen sulfide (H₂S) reduces "ischemia-reperfusion injury" in various experimental animal models, but has not been evaluated in humans. This trial will examine the efficacy and safety of the H₂S-donor sodium thiosulfate (STS) in patients presenting with a STEMI.

STUDY DESIGN

The Groningen Intervention study for the Preservation of cardiac function with STS after STEMI (GIPS-IV) trial (NCT02899364) is a double-blind, randomized, placebo-controlled, multicenter trial, which will enroll 380 patients with a first STEMI. Patients receive STS 12.5 grams intravenously or matching placebo in addition to standard care immediately at arrival at the catheterization laboratory after providing consent. A second dose is administered 6 hours later at the coronary care unit. The primary endpoint is myocardial infarct size as quantified by cardiac magnetic resonance imaging 4 months after randomization. Secondary endpoints include the effect of STS on peak CK-MB during admission and left ventricular ejection fraction and NT-proBNP levels at 4 months follow-up. Patients will be followed-up for 2 years to assess clinical endpoints.

CONCLUSIONS

The GIPS-IV trial is the first study to determine the effect of a H₂S-donor on myocardial infarct size in patients presenting with STEMI.

Oxidative Post-Translational Modifications: A Focus on Cysteine S-Sulfhydration and the Regulation of Endothelial Fitness

Significance: Changes in the oxidative balance can affect cellular physiology and adaptation through redox signaling. The endothelial cells that line blood vessels are particularly sensitive to reactive oxygen species, which can alter cell function by a number of mechanisms, including the oxidative post-translational modification (oxPTM) of proteins on critical cysteine thiols. Such modifications can act as redox-switches to alter the function of targeted proteins. Recent Advances: Mapping the cysteine oxPTM proteome and characterizing the effects of individual oxPTMs to gain insight into consequences for cellular responses has proven challenging. A recent addition to the list of reversible oxPTMs that contributes to cellular redox homeostasis is persulfidation or S-sulfhydration. Critical Issues: It has been estimated that up to 25% of proteins are S-sulfhydrated, making this modification almost as abundant as phosphorylation. In the endothelium, persulfides are generated by the trans-sulfuration pathway that catabolizes cysteine and cystathionine to generate hydrogen sulfide (H₂S) and H₂S-related sulfane sulfur compounds (H₂S_n). This pathway is of particular importance for the vascular system, as the enzyme cystathionine γ lyase (CSE) in endothelial cells accounts for a significant portion of total vascular H₂S/H₂S_n production. Future Directions: Impaired CSE activity in endothelial dysfunction has been linked with marked changes in the endothelial cell S-sulfhydrome and can contribute to the development of atherosclerosis and hypertension. It will be interesting to determine how changes in the S-sulfhydration of specific networks of proteins contribute to endothelial cell physiology and pathophysiology. Antioxid. Redox Signal. 35, 1494-1514.

Methyl p‑hydroxycinnamate exerts anti‑inflammatory effects in mouse models of lipopolysaccharide‑induced ARDS

Methyl p-hydroxycinnamate (MH), an esterified derivative of p-Coumaric acid exerts anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Based on these effects, the present study investigated the protective role of MH in a mouse model of LPS-induced acute respiratory distress syndrome (ARDS). The results demonstrated that administration of LPS (5 mg/kg intranasally) markedly increased the neutrophil/macrophage numbers and levels of inflammatory molecules (TNF-α, IL-6, IL-1β and reactive oxygen species) in the bronchoalveolar lavage fluid (BALF) of mice. On histological examination, the presence of inflammatory cells was observed in the lungs of mice administered LPS. LPS also notably upregulated the secretion of monocyte chemoattractant protein-1 and protein content in BALF as well as expression of inducible nitric oxide synthase in the lungs of mice; it also caused activation of p38 mitogen-activated protein kinase (MAPK) and NF-κB signaling. However, MH treatment significantly suppressed LPS-induced upregulation of inflammatory cell recruitment, inflammatory molecule levels and p38MAPK/NF-κB activation, and also led to upregulation of heme oxygenase-1 (HO-1) expression in the lungs of mice. In addition, the ability of MH to induce HO-1 expression was confirmed in RAW264.7 macrophages. Taken together, the findings of the present study indicated that MH may exert protective effects against airway inflammation in ARDS mice by inhibiting inflammatory cell recruitment and the production of inflammatory molecules.

Impact of Hydrogen Sulfide on Mitochondrial and Bacterial Bioenergetics

This review focuses on the effects of hydrogen sulfide (H2S) on the unique bioenergetic molecular machines in mitochondria and bacteria-the protein complexes of electron transport chains and associated enzymes. H2S, along with nitric oxide and carbon monoxide, belongs to the class of endogenous gaseous signaling molecules. This compound plays critical roles in physiology and pathophysiology. Enzymes implicated in H2S metabolism and physiological actions are promising targets for novel pharmaceutical agents. The biological effects of H2S are biphasic, changing from cytoprotection to cytotoxicity through increasing the compound concentration. In mammals, H2S enhances the activity of FoF1-ATP (adenosine triphosphate) synthase and lactate dehydrogenase via their S-sulfhydration, thereby stimulating mitochondrial electron transport. H2S serves as an electron donor for the mitochondrial respiratory chain via sulfide quinone oxidoreductase and cytochrome c oxidase at low H2S levels. The latter enzyme is inhibited by high H2S concentrations, resulting in the reversible inhibition of electron transport and ATP production in mitochondria. In the branched respiratory chain of Escherichia coli, H2S inhibits the bo3 terminal oxidase but does not affect the alternative bd-type oxidases. Thus, in E. coli and presumably other bacteria, cytochrome bd permits respiration and cell growth in H2S-rich environments. A complete picture of the impact of H2S on bioenergetics is lacking, but this field is fast-moving, and active ongoing research on this topic will likely shed light on additional, yet unknown biological effects.

Sulfide metabolism and the mechanism of torpor

Hibernation is a powerful response of a number of mammalian species to reduce energy during the cold winter season, when food is scarce. Mammalian hibernators survive winter by spending most of the time in a state of torpor, where basal metabolic rate is strongly suppressed and body temperature comes closer to ambient temperature. These torpor bouts are regularly interrupted by short arousals, where metabolic rate and body temperature spontaneously return to normal levels. The mechanisms underlying these changes, and in particular the strong metabolic suppression of torpor, have long remained elusive. As summarized in this Commentary, increasing evidence points to a potential key role for hydrogen sulfide (H2S) in the suppression of mitochondrial respiration during torpor. The idea that H2S could be involved in hibernation originated in some early studies, where exogenous H2S gas was found to induce a torpor-like state in mice, and despite some controversy, the idea persisted. H2S is a widespread signaling molecule capable of inhibiting mitochondrial respiration in vitro and studies found significant in vivo changes in endogenous H2S metabolites associated with hibernation or torpor. Along with increased expression of H2S-synthesizing enzymes during torpor, H2S degradation catalyzed by the mitochondrial sulfide:quinone oxidoreductase (SQR) appears to have a key role in controlling H2S availability for inhibiting respiration. Specifically, in thirteen-lined squirrels, SQR is highly expressed and inhibited in torpor, possibly by acetylation, thereby limiting H2S oxidation and causing inhibition of respiration. H2S may also control other aspects associated with hibernation, such as synthesis of antioxidant enzymes and of SQR itself.

An evolutionary perspective on the interplays between hydrogen sulfide and oxygen in cellular functions

The physiological effects of the endogenously generated hydrogen sulfide (H2S) have been extensively studied in recent years. This review summarized the role of H2S in the origin of life and H2S metabolism in organisms from bacteria to vertebrates, examined the relationship between H2S and oxygen from an evolutionary perspective and emphasized the oxygen-dependent manner of H2S signaling in various physiological and pathological processes. H2S and oxygen are inextricably linked in various cellular functions. H2S is involved in aerobic respiration and stimulates oxidative phosphorylation and ATP production within the cell. Besides, H2S has protective effects on ischemia and reperfusion injury in several organs by acting as an oxygen sensor. Also, emerging evidence suggests the role of H2S is in an oxygen-dependent manner. All these findings indicate the subtle relationship between H2S and oxygen and further explain why H2S, a toxic molecule thriving in an anoxia environment several billion years ago, still affects homeostasis today despite the very low content in the body.

Hydrogen Sulfide and the Immune System

Hydrogen sulfide (H₂S) is the "third gasotransmitter" recognized alongside nitric oxide (NO) and carbon monoxide (CO). H₂S exhibits an array of biological effects in mammalian cells as revealed by studies showing important roles in the cardiovascular system, in cell signalling processes, post-translational modifications and in the immune system. Regarding the latter, using pharmacological and genetic approaches scientists have shown this molecule to have both pro- and anti-inflammatory effects in mammalian systems. The anti-inflammatory effects of H₂S appeared to be due to its inhibitory action on the nuclear factor kappa beta signalling pathway; NF-kB representing a transcription factor involved in the regulation pro-inflammatory mediators like nitric oxide, prostaglandins, and cytokines. In contrast, results from several animal model describe a more complicated picture and report on pro-inflammatory effects linked to exposure to this molecule; linked to dosage used and point of administration of this molecule. Overall, roles for H₂S in several inflammatory diseases spanning arthritis, atherosclerosis, sepsis, and asthma have been described by researchers. In light this work fascinating research, this chapter will cover H₂S biology and its many roles in the immune system.

Two-sided effects of prolonged hypoxia and sulfide exposure on juvenile ark shells (Anadara broughtonii)

Oxygen deficit and sulfide have been restrictive factors in mariculture zones. However, the adaptive mechanism in aquatic lives is still unclear. The commercial ark shells Anadara broughtonii were selected to test the tolerance and adaptive responses to prolonged and intermittent hypoxia with or without exogenous sulfide (mild, moderate, high) by evaluating their behavior, mortality, oxidative level, antioxidant responses, and the MAPK-mediated apoptosis in gills. The results indicated that the clams were tolerant to hypoxia and sulfide exposure but vulnerable during reoxygenation from the challenges. Even so, sulfide had remarkable effect on attenuating the accumulation of reactive oxygen species (ROS) and lipid peroxides caused by reoxygenation from prolonged hypoxia. The increase of glutathione level was probably as an early and primary protective response to prevent the expected reperfusion injury from reoxygenation. The challenges suppressed the oxidative level with a dose-dependent effect of sulfide, with an exception when exposed to mild sulfide. Synchronously, biphasic effects of exogenous sulfide on apoptotic cascade, which was induced by mild sulfide while it was inhibited by higher sulfide, were also detected in gills. The induced or inhibited apoptosis by hypoxia and sulfide kept to a typical ROS-MAPK-CASPASE cascade, desiderating further investigation.

The Role of Protein Persulfidation in Brain Aging and Neurodegeneration

Hydrogen sulfide (H₂S), originally considered a toxic gas, is now a recognized gasotransmitter. Numerous studies have revealed the role of H₂S as a redox signaling molecule that controls important physiological/pathophysiological functions. The underlying mechanism postulated to serve as an explanation of these effects is protein persulfidation (P-SSH, also known as S-sulfhydration), an oxidative posttranslational modification of cysteine thiols. Protein persulfidation has remained understudied due to its instability and chemical reactivity similar to other cysteine modifications, making it very difficult to selectively label. Recent developments of persulfide labeling techniques have started unraveling the role of this modification in (patho)physiology. PSSH levels are important for the cellular defense against oxidative injury, albeit they decrease with aging, leaving proteins vulnerable to oxidative damage. Aging is one of the main risk factors for many neurodegenerative diseases. Persulfidation has been shown to be dysregulated in Parkinson's, Alzheimer's, Huntington's disease, and Spinocerebellar ataxia 3. This article reviews the latest discoveries that link protein persulfidation, aging and neurodegeneration, and provides future directions for this research field that could result in development of targeted drug design.

Hydrogen Sulfide Upregulates Acid-sensing Ion Channels via the MAPK-Erk1/2 Signaling Pathway

Hydrogen sulfide (H₂S) emerged recently as a new gasotransmitter and was shown to exert cellular effects by interacting with proteins, among them many ion channels. Acid-sensing ion channels (ASICs) are neuronal voltage-insensitive Na⁺ channels activated by extracellular protons. ASICs are involved in many physiological and pathological processes, such as fear conditioning, pain sensation, and seizures. We characterize here the regulation of ASICs by H₂S. In transfected mammalian cells, the H₂S donor NaHS increased the acid-induced ASIC1a peak currents in a time- and concentration-dependent manner. Similarly, NaHS potentiated also the acid-induced currents of ASIC1b, ASIC2a, and ASIC3. An upregulation induced by the H₂S donors NaHS and GYY4137 was also observed with the endogenous ASIC currents of cultured hypothalamus neurons. In parallel with the effect on function, the total and plasma membrane expression of ASIC1a was increased by GYY4137, as determined in cultured cortical neurons. H₂S also enhanced the phosphorylation of the extracellular signal-regulated kinase (pErk1/2), which belongs to the family of mitogen-activated protein kinases (MAPKs). Pharmacological blockade of the MAPK signaling pathway prevented the GYY4137-induced increase of ASIC function and expression, indicating that this pathway is required for ASIC regulation by H₂S. Our study demonstrates that H₂S regulates ASIC expression and function, and identifies the involved signaling mechanism. Since H₂S shares several roles with ASICs, as for example facilitation of learning and memory, protection during seizure activity, and modulation of nociception, it may be possible that H₂S exerts some of these effects via a regulation of ASIC function.

Role of Hydrogen Sulfide in Myocardial Ischemia-Reperfusion Injury

ABSTRACT

Hydrogen sulfide (H2S), generally known as a new gas signal molecule after nitric oxide and carbon monoxide, has been found as an important endogenous gasotransmitter in the last few decades, and it plays a significant role in the cardiovascular system both pathologically and physiologically. In recent years, there is growing evidence that H2S provides myocardial protection against myocardial ischemia-reperfusion injury (MIRI), which resulted in an ongoing focus on the possible mechanisms of action accounting for the H2S cardioprotective effect. At present, lots of mechanisms of action have been verified through in vitro and in vivo models of I/R injury, such as S-sulfhydrated modification, antiapoptosis, effects on microRNA, bidirectional effect on autophagy, antioxidant stress, or interaction with NO and CO. With advances in understanding of the molecular pathogenesis of MIRI and pharmacology studies, the design, the development, and the pharmacological characterization of H2S donor drugs have made great important progress. This review summarizes the latest research progress on the role of H2S in MIRI, systematically explains the molecular mechanism of H2S affecting MIRI, and provides a new idea for the formulation of a myocardial protection strategy in the future.

Crescent-Shaped Supramolecular Tetrapeptide Nanostructures

Self-assembly of amphiphilic peptide-based building blocks gives rise to a plethora of interesting nanostructures such as ribbons, fibers, and tubes. However, it remains a great challenge to employ peptide self-assembly to directly produce nanostructures with lower symmetry than these highly symmetric motifs. We report here our discovery that persistent and regular crescent nanostructures with a diameter of 28 ± 3 nm formed from a series of tetrapeptides with the general structure AdKSKSEX (Ad = adamantyl group, KS = lysine residue functionalized with an S-aroylthiooxime (SATO) group, E = glutamic acid residue, and X = variable amino acid residue). In the presence of cysteine, the biological signaling gas hydrogen sulfide (H2S) was released from the SATO units of the crescent nanostructures, termed peptide-H2S donor conjugates (PHDCs), reducing levels of reactive oxygen species (ROS) in macrophage cells. Additional in vitro studies showed that the crescent nanostructures alleviated cytotoxicity induced by phorbol 12-myristate-13-acetate more effectively than common H2S donors and a PHDC of a similar chemical structure, AdKSKSE, that formed short nanoworms instead of nanocrescents. Cell internalization studies indicated that nanocrescent-forming PHDCs were more effective in reducing ROS levels in macrophages because they entered into and remained in cells better than nanoworms, highlighting how nanostructure morphology can affect bioactivity in drug delivery.

Activation of the CaR-CSE/H2S pathway confers cardioprotection against ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury is a multifactorial process triggered when an organ is subjected to transiently reduced blood supply. The result is a cascade of pathological complications and organ damage due to the production of reactive oxygen species following reperfusion. The present study aims to evaluate the role of activated calcium-sensing receptor (CaR)-cystathionine γ-lyase (CSE)/hydrogen sulfide (H2S) pathway in I/R injury. Firstly, an I/R rat model with CSE knockout was constructed. Transthoracic echocardiography, TTC and HE staining were performed to determine the cardiac function of rats following I/R Injury, followed by TUNEL staining observation on apoptosis. Besides, with the attempt to better elucidate how CaR-CSE/H2S affects I/R, in-vitro culture of human coronary artery endothelial cells (HCAECs) was conducted with gadolinium chloride (GdCl3, a CaR agonist), H₂O₂, siRNA against CSE (siCSE), or W7 (a CaM inhibitor). The interaction between CSE and CaM was subsequently detected. Plasma oxidative stress indexes, H2S and CSE, and apoptosis-related proteins were all analyzed following cell apoptosis. We found that H2S elevation led to the improvement whereas CSE knockdown decreased cardiac function in rats with I/R injury. Moreover, oxidative stress injury in I/R rats with CSE knockout was aggravated, while the increased expression of H2S and CSE in the aortic tissues resulted in alleviated the oxidative stress injury. Moreover, increased H2S and CSE levels were found to inhibit cell apoptotic ability in the aortic tissues after I/R injury, thus attenuating oxidative stress injury, accompanied by inhibited expression of apoptosis-related proteins. In HCAECs following oxidative stress treatment, siCSE and CaM inhibitor were observed to reverse the protection of CaR agonist. Coimmunoprecipitation assay revealed the interaction between CSE and CaM. Taken together, all above-mentioned data provides evidence that activation of the CaR-CSE/H2S pathway may confer a potent protective effect in cardiac I/R injury.

Advances in the Protective Mechanism of NO, H2S, and H2 in Myocardial Ischemic Injury

Myocardial ischemic injury is among the top 10 leading causes of death from cardiovascular diseases worldwide. Myocardial ischemia is caused mainly by coronary artery occlusion or obstruction. It usually occurs when the heart is insufficiently perfused, oxygen supply to the myocardium is reduced, and energy metabolism in the myocardium is abnormal. Pathologically, myocardial ischemic injury generates a large number of inflammatory cells, thus inducing a state of oxidative stress. This sharp reduction in the number of normal cells as a result of apoptosis leads to organ and tissue damage, which can be life-threatening. Therefore, effective methods for the treatment of myocardial ischemic injury and clarification of the underlying mechanisms are urgently required. Gaseous signaling molecules, such as NO, H₂S, H₂, and combined gas donors, have gradually become a focus of research. Gaseous signaling molecules have shown anti-apoptotic, anti-oxidative and anti-inflammatory effects as potential therapeutic agents for myocardial ischemic injury in a large number of studies. In this review, we summarize and discuss the mechanism underlying the protective effect of gaseous signaling molecules on myocardial ischemic injury.

The Protective Role of Hydrogen Sulfide Against Obesity-Associated Cellular Stress in Blood Glucose Regulation

Circulating palmitic acid (PA) is increased in obesity and causes metabolic stress, leading to diabetes. This includes the impairment of the glucoregulatory hormone glucagon-like peptide-1 (GLP-1) secreted from intestinal L-cells. Recently, the anti-inflammatory gasotransmitter hydrogen sulfide (H₂S) has been implicated in the enhancement of GLP-1 secretion. We hypothesized that H₂S can reduce the oxidative stress caused by palmitate and play a protective role in L-cell function. This study was conducted on both human and mouse L-cells and a mouse model of Western diet (WD)-induced obesity. PA-induced L-cell stress was assessed using DCF-DA. H₂S was delivered using the donor GYY4137. C57BL/6 mice were fed either chow diet or PA-enriched WD for 20 weeks with ongoing measurements of glycemia and GLP-1 secretion. In both L-cell models, we demonstrated that PA caused an increase in reactive oxygen species (ROS). This ROS induction was partially blocked by the H₂S administration. In mice, the WD elevated body weight in both sexes and elevated fasting blood glucose and lipid peroxidation in males. Additionally, a single GYY4137 injection improved oral glucose tolerance in WD-fed male mice and also enhanced glucose-stimulated GLP-1 release. To conclude, H₂S reduces oxidative stress in GLP-1 cells and can improve glucose clearance in mice.

Safety and Tolerability of Sodium Thiosulfate in Patients with an Acute Coronary Syndrome Undergoing Coronary Angiography: A Dose-Escalation Safety Pilot Study (SAFE-ACS)

Background

In animal studies, hydrogen sulfide (H₂S) has been shown to protect the heart from ischemia-reperfusion injury. This study evaluates the safety and tolerability of the H₂S donor sodium thiosulfate (STS) in patients with acute coronary syndrome (ACS).

Methods

Eighteen patients, undergoing coronary angiography for ACS, received STS intravenously immediately after arrival at the catheterization laboratory according to a “3 + 3 dose-escalation design” with fixed dosing endpoint (0, 2.5, 5, 10, 12.5, and 15 grams). This first dose STS was combined with verapamil and nitroglycerin required for transradial procedures. A second dose STS was administered 6 hours later. Primary endpoint was dose-limiting toxicity, defined as significant hemodynamic instability or death up to 24 hours or before discharge from the coronary care unit. Secondary outcomes included the occurrence of anaphylaxis, nausea, vomiting, and systolic blood pressure (SBP) course.

Results

Sixteen patients received two dosages of STS and two patients one dosage. None of the patients reached the primary endpoint, nor experienced a serious adverse event. We observed a clinically well-tolerated decline in SBP 1 hour after administration of the first STS dose and concomitant verapamil/nitroglycerin. SBP for all patients together reduced 16.8 (8.1–25.5) mmHg (P = 0.0008). No significant decline in SBP occurred after the second dose. Mild nausea was observed in one patient.

Conclusion

This is the first report on sodium thiosulfate administration in patients with acute coronary syndromes. Our data suggest that sodium thiosulfate was well tolerated in this setting. The potential benefit of this intervention has to be examined in larger studies.

Protective mechanisms of hydrogen sulfide in myocardial ischemia

Hydrogen sulfide (H₂ S), which has been identified as the third gaseous signaling molecule after nitric oxide (NO) and carbon monoxide (CO), plays an important role in maintaining homeostasis in the cardiovascular system. Endogenous H₂ S is produced mainly by three endogenous enzymes: cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfur transferase. Numerous studies have shown that H₂ S has a significant protective role in myocardial ischemia. The mechanisms by which H₂ S affords cardioprotection include the antifibrotic and antiapoptotic effects, regulation of ion channels, protection of mitochondria, reduction of oxidative stress and inflammatory response, regulation of microRNA expression, and promotion of angiogenesis. Amplification of NO- and CO-mediated signaling through crosstalk between H₂ S, NO, and CO may also contribute to the cardioprotective effect. Exogenous H₂ S donors are expected to become effective drugs for the treatment of cardiovascular diseases. This review article focuses on the protective mechanisms and potential therapeutic applications of H₂ S in myocardial ischemia.

Neuroprotective effects of ammonium tetrathiomolybdate, a slow-release sulfide donor, in a rodent model of regional stroke

BACKGROUND

Several therapeutic strategies to rescue the brain from ischemic injury have improved outcomes after stroke; however, there is no treatment as yet for reperfusion injury, the secondary damage caused by necessary revascularization. Recently we characterized ammonium tetrathiomolybdate (ATTM), a drug used as a copper chelator over many decades in humans, as a new class of sulfide donor that shows efficacy in preclinical injury models. We hypothesized that ATTM could confer neuroprotection in a relevant rodent model of regional stroke.

METHODS AND RESULTS

Brain ischemia was induced by transient (90-min) middle cerebral artery occlusion (tMCAO) in anesthetized Wistar rats. To mimic a clinical scenario, ATTM (or saline) was administered intravenously just prior to reperfusion. At 24 h or 7 days post-reperfusion, rats were assessed using functional (rotarod test, spontaneous locomotor activity), histological (infarct size), and molecular (anti-oxidant enzyme capacity, oxidative damage, and inflammation) outcome measurements. ATTM-treated animals showed improved functional activity at both 24 h and 7-days post-reperfusion, in parallel with a significant reduction in infarct size. These effects were additionally associated with increased brain antioxidant enzyme capacity, decreased oxidative damage, and a late (7-day) effect on pro-inflammatory cytokine levels and nitric oxide products.

CONCLUSION

ATTM confers significant neuroprotection that, along with its known safety profile in humans, provides encouragement for its development as a novel adjunct therapy for revascularization following stroke.

Dose-Dependent Effects of Long-Term Administration of Hydrogen Sulfide on Myocardial Ischemia-Reperfusion Injury in Male Wistar Rats: Modulation of RKIP, NF-κB, and Oxidative Stress

Decreased circulating levels of hydrogen sulfide (H₂S) are associated with higher mortality following myocardial ischemia. This study aimed at determining the long-term dose-dependent effects of sodium hydrosulfide (NaSH) administration on myocardial ischemia-reperfusion (IR) injury. Male rats were divided into control and NaSH groups that were treated for 9 weeks with daily intraperitoneal injections of normal saline or NaSH (0.28, 0.56, 1.6, 2.8, and 5.6 mg/kg), respectively. At the end of the study, hearts from all rats were isolated and hemodynamic parameters were recorded during baseline and following IR. In isolated hearts, infarct size, oxidative stress indices as well as mRNA expression of H₂S-, nitric oxide (NO)-producing enzymes, and inflammatory markers were measured. In heart tissue following IR, low doses of NaSH (0.28 and 0.56 mg/kg) had no effect, whereas an intermediate dose (1.6 mg/kg), improved recovery of hemodynamic parameters, decreased infarct size, and decreased oxidative stress. It also increased expression of cystathionine γ-lyase (CSE), Raf kinase inhibitor protein (RKIP), endothelial NO synthase (eNOS), and neuronal NOS (nNOS), as well as decreased expression of inducible NOS (iNOS) and nuclear factor kappa-B (NF-κB). At the high dose of 5.6 mg/kg, NaSH administration was associated with worse recovery of hemodynamic parameters and increased infarct size as well as increased oxidative stress. This dose also decreased expression of CSE, RKIP, and eNOS and increased expression of iNOS and NF-κB. In conclusion, chronic treatment with NaSH has a U-shaped concentration effect on IR injury in heart tissue. An intermediate dose was associated with higher CSE-derived H₂S, lower iNOS-derived NO, lower oxidative stress, and inflammation in heart tissue following IR.

Panax Notoginseng Saponins Attenuate Myocardial Ischemia-Reperfusion Injury Through the HIF-1α/BNIP3 Pathway of Autophagy

BACKGROUND AND OBJECTIVE

Panax Notoginseng Saponins (PNS) is a formula of Chinese medicine commonly used for treating ischemia myocardial in China. However, its mechanism of action is yet unclear. This study investigated the effect and the mechanism of PNS on myocardial ischemia-reperfusion injury (MIRI) through the hypoxia-inducible factor 1α (HIF-1α)/bcl-2/adenovirus E1B19kDa-interacting protein3 (BNIP3) pathway of autophagy.

METHODS

We constructed a rat model of myocardial injury and compared among 4 groups (n = 10, each): the sham-operated group (Sham), the ischemia-reperfusion group (IR), the PNS low-dose group, and the PNS high-dose group were pretreated with PNS (30 and 60 mg/kg, respectively). Serum creatine kinase, malonaldehyde (MDA), lactate dehydrogenase, myocardial tissue superoxide dismutase, and reactive oxygen species were detected in rats with myocardial ischemia-reperfusion after the intervention of PNS. The rat myocardial tissue was examined using hematoxylin and eosin (H&E) staining, and the mitochondria of myocardial cells were observed using transmission electron microscopy. The expressions of microtubule-associated protein light chain 3 (LC3), HIF-1α, BNIP3, Beclin-1, and autophagy-related gene-5 (Atg5) in rat myocardial tissue were detected using Western blotting.

RESULTS

The results showed that PNS was significantly protected against MIRI, as evidenced by the decreasing in the concentration of serum CK, MDA, lactate dehydrogenase, and myocardial tissue superoxide dismutase, reactive oxygen species, the attenuation of myocardial tissue histopathological changes and the mitochondrial damages of myocardial cells, and the increase of mitochondria autophagosome in myocardial cells. In addition, PNS significantly increased the expression of LC3 and the ratio of LC3II/LC3I in rat myocardial tissue. Moreover, PNS significantly increased the expression of HIF-1α, BNIP3, Atg5, and Beclin-1 in rat myocardial tissue.

CONCLUSIONS

The protective effect of PNS on MIRI was mainly due to its ability to enhance the mitochondrial autophagy of myocardial tissue through the HIF-1α/BNIP3 pathway.

Hydrogen Sulfide as Potential Regulatory Gasotransmitter in Arthritic Diseases

The social and economic impact of chronic inflammatory diseases, such as arthritis, explains the growing interest of the research in this field. The antioxidant and anti-inflammatory properties of the endogenous gasotransmitter hydrogen sulfide (H₂S) were recently demonstrated in the context of different inflammatory diseases. In particular, H₂S is able to suppress the production of pro-inflammatory mediations by lymphocytes and innate immunity cells. Considering these biological effects of H₂S, a potential role in the treatment of inflammatory arthritis, such as rheumatoid arthritis (RA), can be postulated. However, despite the growing interest in H₂S, more evidence is needed to understand the pathophysiology and the potential of H₂S as a therapeutic agent. Within this review, we provide an overview on H₂S biological effects, on its role in immune-mediated inflammatory diseases, on H₂S releasing drugs, and on systems of tissue repair and regeneration that are currently under investigation for potential therapeutic applications in arthritic diseases.

Enhancement of oxidative stress contributes to increased pathogenicity of the invasive pine wood nematode

Reactive oxygen species (ROS) play important roles in defence response of host plants versus pathogens. While generation and detoxification of ROS is well understood, how varied ability of different isolates of pathogens to overcome host ROS, or ROS contribution to a particular isolate's pathogenicity, remains largely unexplored. Here, we report that transcriptional regulation of the ROS pathway, in combination with the insulin pathway, increases the pathogenicity of invasive species Bursaphelenchus xylophilus. The results showed a positive correlation between fecundity and pathogenicity of different nematode isolates. The virulent isolates from introduced populations in Japan, China and Europe had significantly higher fecundity than native avirulent isolates from the USA. Increased expression of Mn-SOD and reduced expression of catalase/ GPX-5 and H₂O₂ accumulation during invasion are associated with virulent strains. Additional H₂O₂ could improve fecundity of Bu. xylophilus. Furthermore, depletion of Mn-SOD decreased fecundity and virulence of Bu. xylophilus, while the insulin pathway is significantly affected. Thus, we propose that destructive pathogenicity of Bu. xylophilus to pines is partly owing to upregulated fecundity modulated by the insulin pathway in association with the ROS pathway and further enhanced by H₂O₂ oxidative stress. These findings provide a better understanding of pathogenic mechanisms in plant-pathogen interactions and adaptive evolution of invasive species. This article is part of the theme issue 'Biotic signalling sheds light on smart pest management'.

Stimulation of the endogenous hydrogen sulfide synthesis suppresses oxidative-nitrosative stress and restores endothelial-dependent vasorelaxation in old rats

Hydrogen sulfide (H₂S) is an endogenous gas transmitter with profound effects on the cardiovascular system. We hypothesized that stimulation of H₂S synthesis might alleviate age-associated changes in vascular reactivity. Pyridoxal-5-phosphate (PLP), the coenzyme of H₂S-synthesizing enzymes, was administrated to old male Wistar rats per os at a dose of 0.7 mg/kg body mass once a day for 2 weeks. H₂S content in the aortic tissue, markers of oxidative stress, inducible nitric oxide synthase (iNOS) and constitutive nitric oxide synthase (cNOS), arginase activities, and endothelium-dependent vasorelaxation of the aortic rings were studied. Our results showed that PLP restored endogenous H₂S and low molecular weight S-nitrosothiol levels in old rat aorta to the levels detected in adults. PLP significantly reduced diene conjugate content, hydrogen peroxide and peroxynitrite generation rates, and iNOS and arginase activity in the aortic tissue of old rats. PLP also greatly improved acetylcholine-induced relaxation of old rat aorta (47.7% ± 4.8% versus 18.4% ± 4.1% in old rats, P < 0.05) that was abolished by NO inhibition with N-nitro-l-arginine methyl ester hydrochloride (L-NAME) or H₂S inhibition with O-carboxymethylhydroxylamine (O-CMH). Thus, PLP might be used for stimulation of endogenous H₂S synthesis and correction of oxidative and nitrosative stress and vessel tone dysfunction in aging and age-associated diseases.

The Effect of Hydrogen Sulfide on Different Parameters of Human Plasma in the Presence or Absence of Exogenous Reactive Oxygen Species

The main aim of the study is to examine the effect of sodium hydrosulfide (NaHS), an H₂S donor, on the oxidative stress in human plasma in vitro. It also examined the effects of very high concentrations of exogenous hydrogen sulfide on the hemostatic parameters (coagulation and fibrinolytic activity) of human plasma. Plasma was incubated for 5-30 min with different concentrations of NaHS from 0.01 to 10 mM. Following this, lipid peroxidation was measured as a thiobarbituric acid reactive substance (TBARS) concentration and the oxidation of amino acid residues in proteins was measured by determining the amounts of thiol groups and carbonyl groups. Hydrogen peroxide (H₂O₂) and the hydroxyl radical generating oxidation system (Fe/H₂O₂) were used as oxidative stress inducers. Hemostatic factors, such as the maximum velocity of clot formation, fibrin lysis half-time, the activated partial thromboplastin time (APTT), thrombin time (TT), and international normalized ratio (INR), were estimated. Changes in lipid peroxidation, carbonyl group formation, and thiol group oxidation were detected at high concentrations of H₂S (0.1-10 mM), and these results indicate that NaHS (as the precursor of H₂S) may have pro-oxidative effects in human plasma in vitro. Moreover, considering the data presented in this study, we suggest that the oxidative stress stimulated by NaHS (at high concentrations: 1-10 mM) is not involved in changes of the hemostatic activity of plasma.