Antioxidative properties of hydrogen sulfide may involve in its antiadhesive action on blood platelets

Hydrogen sulphide alleviates platelet dysfunction in patients with type 2 diabetes

Hyperglycaemia stimulate platelet activation by reducing platelet H2S concentrations, potentially leading to cardiovascular events. Exogenous supplementation with H2S reversed this abnormal platelet activation under hyperglycaemia.

"One-Stone-Three-Birds" H2S-Photothermal Therapy for Enhanced Thrombolysis and Vascular Healing

Thrombus causes a serious condition characterized by the formation of blood clots in blood vessels or heart, potentially leading to life-threatening emergencies. Photothermal therapy (PTT) serves as a treatment for thrombosis that provides noninvasive thrombus dissolution and fewer bleeding side effects. However, the high temperatures generated by PTT can exacerbate vascular inflammation and promote thrombus recurrence. In this study, a photothermal hydrogen sulfide (H2S) nanogenerator (PSA@ADT-OH) is constructed using a perylene-cored photothermal agent (PSA) coassembled with a H2S donor ADT-OH. The system PSA@ADT-OH demonstrates outstanding targeting and accumulation efficiency against blood flow shear forces. It also provides sustained H2S release at thrombus sites, contributing to antiplatelet aggregation, reactive oxygen species clearance, and vascular healing. This approach opens up new possibilities for advanced thrombus treatment.

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.

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.

Investigating the impact of protein S-sulfhydration modification on vascular diseases: A comprehensive review

The post-translational modification of cysteine through redox reactions, especially S-sulfhydration, plays a critical role in regulating protein activity, interactions, and spatial arrangement. This review focuses on the impact of protein S-sulfhydration on vascular function and its implications in vascular diseases. Dysregulated S-sulfhydration has been linked to the development of vascular pathologies, including aortic aneurysms and dissections, atherosclerosis, and thrombotic diseases. The H2S signaling pathway and the enzyme cystathionine γ-lyase (CSE), which is responsible for H2S generation, are identified as key regulators of vascular function. Additionally, potential therapeutic targets for the treatment of vascular diseases, such as the H2S donor GYY4137 and the HDAC inhibitor entinostat, are discussed. The review also emphasizes the antithrombotic effects of H2S in regulating platelet aggregation and thrombosis. The aim of this review is to enhance our understanding of the function and mechanism of protein S-sulfhydration modification in vascular diseases, and to provide new insights into the clinical application of this modification.

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.

GASOMEDIATOR H2S IN THROMBOSIS AND HEMOSTASIS

This review was aimed to briefly summarize current knowledge of the biological roles of gasomediator H2S in hemostasis and cardiovascular diseases. Since the discovery that mammalian cells are enzymatically producing H2S, this molecule underwent a dramatic metamorphosis from dangerous pollutant to a biologically relevant mediator. As a gasomediator, hydrogen sulfide plays a role of signaling molecule, which is involved in a number of processes in health and disease, including pathogenesis of cardiovascular abnormalities, mainly through modulating different patterns of vasculature functions and thrombotic events. Recently, several studies have provided unequivocal evidence that H2S reduces blood platelet reactivity by inhibiting different stages of platelet activation (platelet adhesion, secretion and aggregation) and thrombus formation. Moreover, H2S changes the structure and function of fibrinogen and proteins associated with fibrinolysis. Hydrogen sulfide regulates proliferation and apoptosis of vascular smooth muscle cells, thus modulating angiogenesis and vessel function. Undoubtedly, H2S is also involved in a multitude of other physiological functions. For example, it exhibits anti-inflammatory effects by inhibiting ROS production and increasing expression of antioxidant enzymes. Some studies have demonstrated the role of hydrogen sulfide as a therapeutic agent in various diseases, including cardiovascular pathologies. Further studies are required to evaluate its importance as a regulator of cell physiology and associated cardiovascular pathological conditions such as myocardial infarction and stroke.

H2S-Releasing Composite: a Gasotransmitter Platform for Potential Biomedical Applications

Hydrogen sulfide (H₂S) is an endogenous gasotransmitter in the human body involved in various physiological functions including cytoprotection, maintaining homeostasis, and regulation of organ development. Therefore, H₂S-releasing polymers that can imitate endogenous H₂S release can offer great therapeutic potential. Despite decades of research, the use of H₂S donors in medical device applications is mostly unexplored largely due to the challenge of the steady H₂S release from a suitable polymeric platform that does not compromise the normal cellular functions of the host. In this work, an exogenous H₂S release system was developed by integrating sodium sulfide (Na₂S), a common H₂S donor, into a medical-grade thermoplastic silicone-polycarbonate-urethane polymer, Carbosil 20 80A (hereon as Carbosil), via a facile solvent evaporation technique. The spatial distribution and nature of Na₂S in Carbosil were characterized through X-ray diffraction (XRD) spectroscopy and field emission scanning electron microscopy (FESEM) with energy-dispersive spectroscopy (EDS), indicating an amorphous phase shift upon incorporating Na₂S in Carbosil. The composite, Na₂S-Carbosil, is responsive in physiological conditions, resulting in sustained H₂S release measured for 3 h. In vitro cellular responses of 3T3 mouse fibroblasts, human lung epithelial (HLE), and primary human umbilical vein endothelial cells (HUVEC) were investigated. Fibroblast cells showed cell proliferation in 24 h and complete cell migration in 42 h in vitro. The Na₂S-Carbosil composites were cytocompatible toward HUVEC and HLE cells. This study provided important in vitro proof of concept that warrants potential use of these H₂S-releasing platforms in engineering biomedical devices, tissue engineering, and drug delivery applications.

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.

Hydrogen sulfide: a gaseous signaling molecule modulates tissue homeostasis: implications in ophthalmic diseases

Hydrogen sulfide (H2S) serves as a gasotransmitter in the regulation of organ development and maintenance of homeostasis in tissues. Its abnormal levels are associated with multiple human diseases, such as neurodegenerative disease, myocardial injury, and ophthalmic diseases. Excessive exposure to H2S could lead to cellular toxicity, orchestrate pathological process, and increase the risk of various diseases. Interestingly, under physiological status, H2S plays a critical role in maintaining cellular physiology and limiting damages to tissues. In mammalian species, the generation of H2S is catalyzed by cystathionine beta-synthase (CBS), cystathionine gamma-lyase (CSE), 3-mercapto-methylthio pyruvate aminotransferase (3MST) and cysteine aminotransferase (CAT). These enzymes are found inside the mammalian eyeballs at different locations. Their aberrant expression and the accumulation of substrates and intermediates can change the level of H2S by orders of magnitude, causing abnormal structures or functions in the eyes. Detailed investigations have demonstrated that H2S donors' administration could regulate intraocular pressure, protect retinal cells, inhibit oxidative stress and alleviate inflammation by modulating the function of intra or extracellular proteins in ocular tissues. Thus, several slow-releasing H2S donors have been shown to be promising drugs for treating multiple diseases. In this review, we discuss the biological function of H2S metabolism and its application in ophthalmic diseases.

Regulation of vascular tone homeostasis by NO and H2S: Implications in hypertension

Nitric oxide (NO) and hydrogen sulfide (H2S) are two gasotransmitters that are produced in the vasculature and contribute to the regulation of vascular tone. NO and H2S are synthesized in both vascular smooth muscle and endothelial cells; NO functions primarily through the sGC/cGMP pathway, and H2S mainly through activation of the ATP-dependent potassium channels; both leading to relaxation of vascular smooth muscle cells. A deficit in the NO/H2S homeostasis is involved in the pathogenesis of various cardiovascular diseases, especially hypertension. It is now becoming increasingly clear that there are important interactions between NO and H2S and that have a profound impact on vascular tone and this may provide insights into the new therapeutic interventions. The aim of this review is to provide a better understanding of individual and interactive roles of NO and H2S in vascular biology. Overall, available data indicate that both NO and H2S contribute to vascular (patho)physiology and in regulating blood pressure. In addition, boosting NO and H2S using various dietary sources or donors could be a hopeful therapeutic strategy in the management of hypertension.

The effects of hydrogen sulfide on platelet-leukocyte aggregation and microvascular thrombolysis

The volatile transmitter hydrogen sulfide (H₂S) is known for its various functions in vascular biology. This study evaluates the effect of the H₂S-donor GYY4137 (GYY) on thrombus stability and microvascular thrombolysis. Human whole blood served for all in vitro studies and was analyzed in a resting state, after stimulation with thrombin-receptor activating peptide (TRAP) and after incubation with 10 or 30 mM GYY or its vehicle DMSO following TRAP-activation, respectively. As a marker for thrombus stability, platelet-leukocyte aggregation was assessed using flow cytometry after staining of human whole blood against CD62P and CD45, respectively. Furthermore, morphology and quantity of platelet-leukocyte aggregation were studied by means of scanning electron microscopy (scanning EM). Therefore, platelets were stained for CD62P followed by immuno gold labeling. In vivo, the dorsal skinfold chamber preparation was performed for light/dye induction of thrombi in arterioles and venules using intravital fluorescence microscopy. Thrombolysis was assessed 10 and 22 h after thrombus induction and treatment with the vehicle, GYY, or recombinant tissue plasminogen activator (rtPA). Flow cytometry revealed an increase of CD62P/CD45 positive aggregates after TRAP stimulation of human whole blood, which was significantly reduced by preincubation with 30 mM GYY. Scanning EM additionally showed a reduced platelet-leukocyte aggregation and a decreased leukocyte count within the aggregates after preincubation with GYY compared to TRAP stimulation alone. Further on, morphological signs of platelet activation were found markedly reduced upon treatment with GYY. In mice, both GYY and rtPA significantly accelerated arteriolar and venular thrombolysis compared to the vehicle control. In conclusion, GYY impairs thrombus stability by reducing platelet-leukocyte aggregation and thereby facilitates endogenous thrombolysis.

Hydrogen Sulfide as a "Double-Faced" Compound: One with Pro- and Antioxidant Effect

Hydrogen sulfide (H₂S), like other gasotransmitters such as nitric oxide (NO^•) and carbon monoxide (CO), acts as a signaling molecule in various biological systems. It may also regulate the oxidative stress observed in several diseases sometimes associated with changes of H₂S concentration. This chapter describes the "double face" of hydrogen sulfide as both an antioxidant and a prooxidant in biological systems. One proposed mechanism by which H₂S exerts its antioxidative effects is its ability to modulate the concentration of glutathione, which is a very important physiological antioxidant. This chapter discusses the interactions of H₂S with various reactive oxygen species and reactive nitrogen species, including the superoxide radical anion [Formula: see text] , hydrogen peroxide (H₂O₂), and peroxynitrite anion (ONOO^-), which is produced in a rapid reaction between [Formula: see text] and NO^•.

Medical Functions of Hydrogen Sulfide

Hydrogen sulfide (H(2)S) is a gasomediator synthesized from L- and D-cysteine in various tissues. It is involved in a number of physiological and pathological processes. H(2)S exhibits antiatherosclerotic, vasodilator, and proangiogenic properties, and protects the kidney and heart from damage following ischemia/reperfusion injury. H(2)S donors may be natural or synthetic, and may be used for the safe treatment of a wide range of diseases. This review article summarizes the current state of knowledge of the therapeutic function of H(2)S.

Hydrogen sulfide decreases the plasma lipid peroxidation induced by homocysteine and its thiolactone

Hydrogen sulfide (H2S) has been investigated widely in recent years. H2S plays a variety of roles in different biological systems, including cardiovascular system. It is the final product of amino acids metabolism, which contains sulfur-cysteine and homocysteine (Hcy). In human plasma, there are several various forms of homocysteine: free Hcy, protein-bound Hcy (S-linked, and N-linked), and homocysteine thiolactone (HTL). Our previous works have shown that both Hcy in the reduced form and its thiolactone may modify fibrinolysis, coagulation process, and biological activity of blood platelets. Moreover, we have observed that HTL, like its precursor-Hcy stimulated the generation of superoxide anion radicals (O 2 (-•) ) in blood platelets. The aim of our study in vitro was to establish the influence of sodium hydrosulfide (NaHS, as a fast-releasing H2S donor; at tested concentrations: 10-1000 µM) on the plasma lipid peroxidation induced by the reduced Hcy (at final concentrations of 0.01-1 mM) and HTL (at final concentrations of 0.1-1 µM). Our results indicate that 10 and 100 µM NaHS decreased the lipid peroxidation in plasma treated with 1 mM Hcy or 1 µM HTL (when NaHS and Hcy/HTL were added to plasma together). The protective effect of 10 and 100 µM NaHS against the lipid peroxidation in plasma preincubated with 1 mM Hcy or 1 µM HTL was also observed. Considering the data presented in this study, we suggest that the lipid peroxidation (induced by different forms of homocysteine) may be reduced by hydrogen sulfide.

Hydrogen sulfide in signaling pathways

For a long time hydrogen sulfide (H₂S) was considered a toxic compound, but recently H₂S (at low concentrations) has been found to play an important function in physiological processes. Hydrogen sulfide, like other well-known compounds - nitric oxide (NO) and carbon monoxide (CO) is a gaseous intracellular signal transducer. It regulates the cell cycle, apoptosis and the oxidative stress. Moreover, its functions include neuromodulation, regulation of cardiovascular system and inflammation. In this review, I focus on the metabolism of hydrogen sulfide (including enzymatic pathways of H₂S synthesis from l- and d-cysteine) and its signaling pathways in the cardiovascular system and the nervous system. I also describe how hydrogen sulfide may be used as therapeutic agent, i.e. in the cardiovascular diseases.

Hydrogen sulfide as a vasculoprotective factor

Hydrogen sulfide is a novel mediator with the unique properties of a gasotransmitter and many and varied physiological effects. Included in these effects are a number of cardiovascular effects that are proving beneficial to vascular health. Specifically, H2S can elicit vasorelaxation, prevention of inflammation and leukocyte adhesion, anti-proliferative effects and anti-thrombotic effects. Additionally, H2S is a chemical reductant and nucleophile that is capable of inhibiting the production of reactive oxygen species, scavenging and neutralising reactive oxygen species and boosting the efficacy of endogenous anti-oxidant molecules. These result in resistance to oxidative stress, protection of vascular endothelial function and maintenance of blood flow and organ perfusion. H2S has been shown to be protective in hypertension, atherosclerosis and under conditions of vascular oxidative stress, and deficiency of endogenous H2S production is linked to cardiovascular disease states. Taken together, these effects suggest that H2S has a physiological role as a vasculoprotective factor and that exogenous H2S donors may be useful therapeutic agents. This review article will discuss the vascular effects and anti-oxidant properties of H2S as well as examine the protective role of H2S in some important vascular disease states.

Endogenous hydrogen sulfide in perivascular adipose tissue: role in the regulation of vascular tone in physiology and pathology

Hydrogen sulfide (H2S) is synthesized from L-cysteine by cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE), and is enzymatically metabolized in mitochondria by sulfide:quinone oxidoreductase (SQR). Recent studies have indicated that H2S is synthesized by CSE in perivascular adipose tissue (PVAT), and is responsible for the anticontractile effect of PVAT on adjacent vessels. The lipophilic statin atorvastatin increases PVAT-derived H2S by suppressing its mitochondrial oxidation; the effect that results from statin-induced depletion of ubiquinone. Experimental obesity induced by a highly palatable diet has a time-dependent effect on H2S in PVAT. Adipose tissue hypoxia suppresses H2S oxidation and increases its level in short-term obesity not associated with insulin resistance. In contrast, in long-term obesity, insulin resistance and (or) hyperinsulinemia result in the down-regulation of CSE and H2S deficiency, which is corrected by treatment with the insulin sensitizer rosiglitazone. In addition, cannabinoid CB1 receptor agonist administered for 2 weeks increases H2S by impairing mitochondria biogenesis. This indicates that the rate of mitochondrial H2S oxidation plays an important role in the regulation of H2S level in PVAT. Up-regulation of H2S signaling in short-term obesity and (or) by elevated endocannabinoids may be a compensatory mechanism that maintains vascular tone, despite endothelial dysfunction.

Effect of the hydrogen sulfide donor GYY4137 on platelet activation and microvascular thrombus formation in mice

This study evaluates the effect of the H2S donor GYY4137 (GYY) on adhesion molecule expression, protein S-sulfhydration and morphology of platelets in vitro and on kinetics of microvascular thrombus formation in vivo. Using flowcytometry, untreated resting, TRAP-activated, or TRAP-activated and GYY-exposed human platelets were studied for expression of P-selectin, GPIb and GPIIb/IIIa as well as for fibrinogen binding. By means of electron microscopy, platelet morphology and intracellular granule numbers were assessed. Platelet shape change was studied using immunohistochemistry for P-selectin, NSF and F-actin by SR-SIM. Biotin switch assay served for the analysis of platelet protein S-sulfhydration by GYY. Using the FeCl3 and the light/dye model in dorsal skinfold chamber-equipped mice, the effect of GYY and its vehicle DMSO was studied on venular thrombus formation and tail-vein bleeding time. Soluble (s)P-selectin plasma concentrations were measured in GYY- or DMSO-treated animals. Exposure to GYY increased the S-sulfhydration of platelet proteins. GYY reduced dose-dependently the TRAP-induced adhesion molecule expression and attenuated the morphological signs of TRAP-associated platelet activation. In mice, GYY caused a significant prolongation of venular thrombus formation and tail-vein bleeding time. Application of an anti-P-selectin antibody in DMSO-exposed animals prolonged thrombosis formation comparably as GYY did. GYY reversed the TRAP-induced distribution of P-selectin at the plasma membrane of platelets. This indicates reduced exocytosis and shedding of P-selectin, which is supported by significantly lower sP-selectin concentrations in GYY- vs. DMSO-treated mice. H2S acts anti-thrombotic and seems to regulate thrombogenesis by interference with platelet activation and adhesion molecule-mediated aggregation.