Amelioration of mitochondrial dysfunction in heart failure through S-sulfhydration of Ca2+/calmodulin-dependent protein kinase II

Effect of Sodium Thiosulfate Pre-Treatment on Renal Ischemia-Reperfusion Injury in Kidney Transplantation

We recently reported in a rat model of kidney transplantation that the addition of sodium thiosulfate (STS) to organ preservation solution improved renal graft quality and prolonged recipient survival. The present study investigates whether STS pre-treatment would produce a similar effect. In vitro, rat kidney epithelial cells were treated with 150 μM STS before and/or during exposure to hypoxia followed by reoxygenation. In vivo, donor rats were treated with PBS or 2.4 mg/kg STS 30 min before donor kidneys were procured and stored in UW or UW+150 μM STS solution at 4 °C for 24 h. Renal grafts were then transplanted into bilaterally nephrectomised recipient rats which were then sacrificed on post-operative day 3. STS pre-treatment significantly reduced cell death compared to untreated and other treated cells in vitro (p < 0.05), which corresponded with our in vivo result (p < 0.05). However, no significant differences were observed in other parameters of tissue injury. Our results suggest that STS pre-treatment may improve renal graft function after transplantation.

The role of hydrogen sulfide in the regulation of necroptosis across various pathological processes

Necroptosis is a programmed cell death form executed by receptor-interacting protein kinase (RIPK) 1, RIPK3 and mixed lineage kinase domain-like protein (MLKL), which assemble into an oligomer called necrosome. Accumulating evidence reveals that necroptosis participates in many types of pathological processes. Hence, clarifying the mechanism of necroptosis in pathological processes is particularly important for the prevention and treatment of various diseases. For over 300 years, hydrogen sulfide (H2S) has been widely known in the scientific community as a toxic and foul-smelling gas. However, after discovering the important physiological and pathological functions of H2S, human understanding of this small molecule changed, believing that H2S is the third gas signaling molecule after carbon monoxide (CO) and nitric oxide (NO). H2S plays an important role in various diseases, but the related mechanisms are not yet fully understood. In recent years, more and more studies have shown that H2S regulation of necroptosis is involved in various pathological processes. Herein, we focus on the recent progress on the role of H2S regulation of necroptosis in different pathological processes and profoundly analyze the related mechanisms.

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.

Hydrogen sulfide maintains mitochondrial homeostasis and regulates ganoderic acids biosynthesis by SQR under heat stress in Ganoderma lucidum

Hydrogen sulfide (H2S) has recently been recognized as an important gaseous transmitter with multiple physiological effects in various species. Previous studies have shown that H2S alleviated heat-induced ganoderic acids (GAs) biosynthesis, an important quality index of Ganoderma lucidum. However, a comprehensive understanding of the physiological effects and molecular mechanisms of H2S in G. lucidum remains unexplored. In this study, we found that heat treatment reduced the mitochondrial membrane potential (MMP) and mitochondrial DNA copy number (mtDNAcn) in G. lucidum. Increasing the intracellular H2S concentration through pharmacological and genetic means increased the MMP level, mtDNAcn, oxygen consumption rate level and ATP content under heat treatment, suggesting a role for H2S in mitigating heat-caused mitochondrial damage in G. lucidum. Further results indicated that H2S activates sulfide-quinone oxidoreductase (SQR) and complex III (Com III), thereby maintaining mitochondrial homeostasis under heat stress in G. lucidum. Moreover, SQR also mediated the negative regulation of H2S to GAs biosynthesis under heat stress. Furthermore, SQR might be persulfidated under heat stress in G. lucidum. Thus, our study reveals a novel physiological function and molecular mechanism of H2S signalling under heat stress in G. lucidum with broad implications for research on the environmental response of microorganisms.

Sulfur metabolism as a new therapeutic target of heart failure

Sulfur-based redox signaling has long attracted attention as critical mechanisms underlying the development of cardiac diseases and resultant heart failure. Especially, post-translational modifications of cysteine (Cys) thiols in proteins mediate oxidative stress-dependent cardiac remodeling including myocardial hypertrophy, senescence, and interstitial fibrosis. However, we recently revealed the existence of Cys persulfides and Cys polysulfides in cells and tissues, which show higher redox activities than Cys and substantially contribute to redox signaling and energy metabolism. We have established simple evaluation methods that can detect polysulfides in proteins and inorganic polysulfides in cells and revealed that polysulfides abundantly expressed in normal hearts are dramatically catabolized by exposure to ischemic/hypoxic and environmental electrophilic stress, which causes vulnerability of the heart to mechanical load. Accumulation of hydrogen sulfide, a nucleophilic catabolite of persulfides/polysulfides, may lead to reductive stress in ischemic hearts, and perturbation of polysulfide catabolism can improve chronic heart failure after myocardial infarction in mice. This review focuses on the (patho)physiological role of sulfur metabolism in hearts, and proposes that sulfur catabolism during ischemic/hypoxic stress has great potential as a new therapeutic strategy for the treatment of ischemic heart failure.

Cystathionine γ-lyase S-sulfhydrates SIRT1 to attenuate myocardial death in isoprenaline-induced heart failure

OBJECTIVE

Hydrogen sulfide (H₂S), the third gasotransmitter, plays a critical role in protecting against heart failure. Sirtuin-1 (SIRT1) is a highly conserved histone deacetylase that has a protective role in the treatment of heart failure by regulating the deacetylation of some functional proteins. This study investigates the interaction between SIRT1 and H₂S in heart failure and the underlying mechanisms.

METHODS AND RESULTS

Using endogenous H₂S-generating enzyme cystathionine γ-lyase (CSE) knockout mice, we found that CSE deficiency aggravated isoprenaline-induced cardiac injury. Treatment with H₂S attenuated atrial natriuretic peptide level, brain natriuretic peptide level, improved cardiac function. Moreover, H₂S treatment potentiated myocardial SIRT1 expression. Silencing CSE abolished intracellular SIRT1 expression. Furthermore, CSE/ H₂S S-sulfhydrated SIRT1 at its zinc finger domains and augmented its zinc ion binding activity to stabilize the alpha-helix structure.

DISCUSSION

In conclusion, these results uncover that a novel mechanism that CSE/H₂S S-sulfhydrated SIRT1 to prevent heart dysfunction through modulating its activity.

Sulfur signaling pathway in cardiovascular disease

Hydrogen sulfide (H2S) and sulfur dioxide (SO2), recognized as endogenous sulfur-containing gas signaling molecules, were the third and fourth molecules to be identified subsequent to nitric oxide and carbon monoxide (CO), and exerted diverse biological effects on the cardiovascular system. However, the exact mechanisms underlying the actions of H2S and SO2 have remained elusive until now. Recently, novel post-translational modifications known as S-sulfhydration and S-sulfenylation, induced by H2S and SO2 respectively, have been proposed. These modifications involve the chemical alteration of specific cysteine residues in target proteins through S-sulfhydration and S-sulfenylation, respectively. H2S induced S-sulfhydrylation can have a significant impact on various cellular processes such as cell survival, apoptosis, cell proliferation, metabolism, mitochondrial function, endoplasmic reticulum stress, vasodilation, anti-inflammatory response and oxidative stress in the cardiovascular system. Alternatively, S-sulfenylation caused by SO2 serves primarily to maintain vascular homeostasis. Additional research is warranted to explore the physiological function of proteins with specific cysteine sites, despite the considerable advancements in comprehending the role of H2S-induced S-sulfhydration and SO2-induced S-sulfenylation in the cardiovascular system. The primary objective of this review is to present a comprehensive examination of the function and potential mechanism of S-sulfhydration and S-sulfenylation in the cardiovascular system. Proteins that undergo S-sulfhydration and S-sulfenylation may serve as promising targets for therapeutic intervention and drug development in the cardiovascular system. This could potentially expedite the future development and utilization of drugs related to H2S and SO2.

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

Inhibition of the voltage-gated potassium channel Kv1.5 by hydrogen sulfide attenuates remodeling through S-nitrosylation-mediated signaling

The voltage-gated K+ channel plays a key role in atrial excitability, conducting the ultra-rapid rectifier K+ current (IKur) and contributing to the repolarization of the atrial action potential. In this study, we examine its regulation by hydrogen sulfide (H2S) in HL-1 cardiomyocytes and in HEK293 cells expressing human Kv1.5. Pacing induced remodeling resulted in shorting action potential duration, enhanced both Kv1.5 channel and H2S producing enzymes protein expression in HL-1 cardiomyocytes. H2S supplementation reduced these remodeling changes and restored action potential duration through inhibition of Kv1.5 channel. H2S also inhibited recombinant hKv1.5, lead to nitric oxide (NO) mediated S-nitrosylation and activated endothelial nitric oxide synthase (eNOS) by increased phosphorylation of Ser1177, prevention of NO formation precluded these effects. Regulation of Ikur by H2S has important cardiovascular implications and represents a novel and potential therapeutic target.

Hydrogen sulfide alleviates mitochondrial damage and ferroptosis by regulating OPA3-NFS1 axis in doxorubicin-induced cardiotoxicity

Ferroptosis is a major cause of cardiotoxicity induced by doxorubicin (DOX). Previous studies have shown that hydrogen sulfide (H₂S) inhibits ferroptosis in cardiomyocytes and myoblasts, but the underlying mechanism has not been fully elucidated. In this study, we investigated the role of H₂S in protecting against DOX-induced cardiotoxicity both in vivo and in vitro, and elucidated the potential mechanisms involved. We found that DOX downregulated the expression of glutathione peroxidase 4 (GPX4) and NFS1, and upregulated the expression of acyl-coenzyme A synthetase long-chain family member 4 (ACSL4) expression level, resulting in increased lipid peroxidation and ferroptosis. Additionally, DOX inhibited MFN2 expression and increased DRP1 and FIS1 expression, leading to abnormal mitochondrial structure and function. In contrast, exogenous H₂S inhibited DOX-induced ferroptosis by restoring GPX4 and NFS1 expression, and reducing lipid peroxidation in H9C2 cells. This effect was similar to that of the ferroptosis antagonist ferrostatin-1 (Fer-1) in protecting against DOX-induced cardiotoxicity. We further demonstrated that the protective effect of H₂S was mediated by the key mitochondrial membrane protein optic atrophy 3 (OPA3), which was downregulated by DOX and restored by exogenous H₂S. Overexpression of OPA3 alleviated DOX-induced mitochondrial dysfunction and ferroptosis both in vivo and in vitro. Mechanistically, NFS1 has an inhibitory effect on ferroptosis, and NFS1 deficiency increases the susceptibility of cardiomyocytes to ferroptosis. OPA3 is involved in the regulation of ferroptosis by interacting with NFS1. Post-translationally, DOX promoted OPA3 ubiquitination, while exogenous H₂S antagonized OPA3 ubiquitination by promoting OPA3 s-sulfhydration. In summary, our findings suggested that H₂S protects against DOX-induced cardiotoxicity by inhibiting ferroptosis via targeting the OPA3-NFS1 axis. This provides a potential therapeutic strategy for the treatment of DOX-induced cardiotoxicity.

Sulfide regulation of cardiovascular function in health and disease

Hydrogen sulfide (H2S) has emerged as a gaseous signalling molecule with crucial implications for cardiovascular health. H2S is involved in many biological functions, including interactions with nitric oxide, activation of molecular signalling cascades, post-translational modifications and redox regulation. Various preclinical and clinical studies have shown that H2S and its synthesizing enzymes - cystathionine γ-lyase, cystathionine β-synthase and 3-mercaptosulfotransferase - can protect against cardiovascular pathologies, including arrhythmias, atherosclerosis, heart failure, myocardial infarction and ischaemia-reperfusion injury. The bioavailability of H2S and its metabolites, such as hydropersulfides and polysulfides, is substantially reduced in cardiovascular disease and has been associated with single-nucleotide polymorphisms in H2S synthesis enzymes. In this Review, we highlight the role of H2S, its synthesizing enzymes and metabolites, their roles in the cardiovascular system, and their involvement in cardiovascular disease and associated pathologies. We also discuss the latest clinical findings from the field and outline areas for future study.

Role of Mitophagy in Myocardial Ischemia/Reperfusion Injury and Chinese Medicine Treatment

Mitophagy is one of the important targets for the prevention and treatment of myocardial ischemia/reperfusion injury (MIRI). Moderate mitophagy can remove damaged mitochondria, inhibit excessive reactive oxygen species accumulation, and protect mitochondria from damage. However, excessive enhancement of mitophagy greatly reduces adenosine triphosphate production and energy supply for cell survival, and aggravates cell death. How dysfunctional mitochondria are selectively recognized and engulfed is related to the interaction of adaptors on the mitochondrial membrane, which mainly include phosphatase and tensin homolog deleted on chromosome ten (PTEN)-induced kinase 1/Parkin, hypoxia-inducible factor-1 α/Bcl-2 and adenovirus e1b19k Da interacting protein 3, FUN-14 domain containing protein 1 receptor-mediated mitophagy pathway and so on. In this review, the authors briefly summarize the main pathways currently studied on mitophagy and the relationship between mitophagy and MIRI, and incorporate and analyze research data on prevention and treatment of MIRI with Chinese medicine, thereby provide relevant theoretical basis and treatment ideas for clinical prevention of MIRI.

Cystathionine γ lyase S-sulfhydrates Drp1 to ameliorate heart dysfunction

Hydrogen sulfide (H₂S), produced by cystathionine γ lyase (CSE), is an important endogenous gasotransmitter to maintain heart function. However, the molecular mechanism for how H₂S influences the mitochondrial morphology during heart failure remains poorly understood. Here, we found that CSE/H₂S pathway mediated cardiac function and mitochondrial morphology through regulating dynamin related protein 1 (Drp1) activity and translocation. Mechanistically, elevation of H₂S levels by CSE overexpression declined protein level, phosphorylation (Ser 616), oligomerization and GTPase activity of Drp1 by S-sulfhydration in mouse hearts. Interestingly, Drp1 S-sulfhydration directly competed with S-nitrosylation by nitric oxide at the specific cysteine 607. The non-S-sulfhydration of Drp1 mutation (C607A) attenuated the regulatory effect of H₂S on Drp1 activation, mitochondrial fission and heart function. Moreover, the non-canonical role of Drp1 mediated isoprenaline-induced mitochondrial dysfunction and cardiomyocyte death through interaction with voltage-dependent anion channel 1. These results uncover that a novel mechanism that H₂S S-sulfhydrated Drp1 at cysteine 607 to prevent heart failure through modulating its activity and mitochondrial translocation. Our findings also provide initial evidence demonstrating that Drp1 may be a critical regulator as well as an effective strategy for heart dysfunction.

Protein S-sulfhydration: Unraveling the prospective of hydrogen sulfide in the brain, vasculature and neurological manifestations

Hydrogen sulfide (H₂S) and hydrogen polysulfides (H₂S_n) are essential regulatory signaling molecules generated by the entire body, including the central nervous system. Researchers have focused on the classical H₂S signaling from the past several decades, whereas the last decade has shown the emergence of H₂S-induced protein S-sulfhydration signaling as a potential therapeutic approach. Cysteine S-persulfidation is a critical paradigm of post-translational modification in the process of H₂S signaling. Additionally, studies have shown the cross-relationship between S-sulfhydration and other cysteine-induced post-translational modifications, namely nitrosylation and carbonylation. In the central nervous system, S-sulfhydration is involved in the cytoprotection through various signaling pathways, viz. inflammatory response, oxidative stress, endoplasmic reticulum stress, atherosclerosis, thrombosis, and angiogenesis. Further, studies have demonstrated H₂S-induced S-sulfhydration in regulating different biological processes, such as mitochondrial integrity, calcium homeostasis, blood-brain permeability, cerebral blood flow, and long-term potentiation. Thus, protein S-sulfhydration becomes a crucial regulatory molecule in cerebrovascular and neurodegenerative diseases. Herein, we first described the generation of intracellular H₂S followed by the application of H₂S in the regulation of cerebral blood flow and blood-brain permeability. Further, we described the involvement of S-sulfhydration in different biological and cellular functions, such as inflammatory response, mitochondrial integrity, calcium imbalance, and oxidative stress. Moreover, we highlighted the importance of S-sulfhydration in cerebrovascular and neurodegenerative diseases.

Hydrogen sulfide-induced post-translational modification as a potential drug target

Hydrogen sulfide (H₂S) is one of the three known gas signal transducers, and since its potential physiological role was reported, the literature on H₂S has been increasing. H₂S is involved in processes such as vasodilation, neurotransmission, angiogenesis, inflammation, and the prevention of ischemia-reperfusion injury, and its mechanism remains to be further studied. At present, the role of post-translational processing of proteins has been considered as a possible mechanism for the involvement of H₂S in a variety of physiological processes. Current studies have shown that H₂S is involved in S-sulfhydration, phosphorylation, and S-nitrosylation of proteins, etc. This paper focuses on the effects of protein modification involving H₂S on physiological and pathological processes, looking forward to providing guidance for subsequent research.

Association of DNA methylation and transcriptome reveals epigenetic etiology of heart failure

Epigenetic modifications viz. DNA methylation, histone modifications, and RNA-based alterations play a crucial role in the development of cardiovascular diseases. In this study, we investigated DNA methylation with an aim to reveal the epigenetic etiology of heart failure. Sprague-Dawley rats surviving myocardial infarction developed acute heart failure in 1 week. Genomic DNA methylation changes were profiled by bisulfite sequencing, and gene expression levels were analyzed by RNA-seq in failing and sham-operation hearts. A total of 3480 differentially methylated genes in the promoter regions including transcriptional start site and 1934 transcriptome-altered genes were identified in the defected hearts. Common differential genes were enriched by the gene ontology, Kyoto Encyclopedia of Genes and Genomes pathway, and protein-protein interaction for HF phenotypes. Among these, Mettl11b, HDAC3, HDAC11, ubiquitination-related genes, and snoRNAs are new epigenetic classifiers that had not been reported yet, which may be important regulators in HF.

Injectable Nanocomposite Implants Reduce ROS Accumulation and Improve Heart Function after Infarction

In a myocardial infarction, blood supply to the left ventricle is abrogated due to blockage of one of the coronary arteries, leading to ischemia, which further triggers the generation of reactive oxygen species (ROS). These sequential processes eventually lead to the death of contractile cells and affect the integrity of blood vessels, resulting in the formation of scar tissue. A new heart therapy comprised of cardiac implants encapsulated within an injectable extracellular matrix-gold nanoparticle composite hydrogel is reported. The particles on the collagenous fibers within the hydrogel promote fast transfer of electrical signal between cardiac cells, leading to the functional assembly of the cardiac implants. The composite hydrogel is shown to absorb reactive oxygen species in vitro and in vivo in mice ischemia reperfusion model. The reduction in ROS levels preserve cardiac tissue morphology and blood vessel integrity, reduce the scar size and the inflammatory response, and significantly prevent the deterioration of heart function.

Cardioprotective effects of hydrogen sulfide in attenuating myocardial ischemia‑reperfusion injury (Review)

Ischemic heart disease is one of the major causes of cardiovascular‑related mortality worldwide. Myocardial ischemia can be attenuated by reperfusion that restores the blood supply. However, injuries occur during blood flow restoration that induce cardiac dysfunction, which is known as myocardial ischemia‑reperfusion injury (MIRI). Hydrogen sulfide (H₂S), the third discovered endogenous gasotransmitter in mammals (after NO and CO), participates in various pathophysiological processes. Previous in vitro and in vivo research have revealed the protective role of H₂S in the cardiovascular system that render it useful in the protection of the myocardium against MIRI. The cardioprotective effects of H₂S in attenuating MIRI are summarized in the present review.

Hydrogen sulphide reduced the accumulation of lipid droplets in cardiac tissues of db/db mice via Hrd1 S-sulfhydration

Accumulation of lipid droplets (LDs) induces cardiac dysfunctions in type 2 diabetes patients. Recent studies have shown that hydrogen sulphide (H₂ S) ameliorates cardiac functions in db/db mice, but its regulation on the formation of LDs in cardiac tissues is unclear. Db/db mice were injected with NaHS (40 μmol·kg^-1 ) for twelve weeks. H9c2 cells were treated with high glucose (40 mmol/L), oleate (200 µmol/L), palmitate (200 µmol/L) and NaHS (100 µmol/L) for 48 hours. Plasmids for the overexpression of wild-type Hrd1 and Hrd1 mutated at Cys115 were constructed. The interaction between Hrd1 and DGAT1 and DGAT2, the ubiquitylation level of DGAT1 and 2, the S-sulfhydration of Hrd1 were measured. Exogenous H₂ S ameliorated the cardiac functions, decreased ER stress and reduced the number of LDs in db/db mice. Exogenous H₂ S could elevate the ubiquitination level of DGAT 1 and 2 and increased the expression of Hrd1 in cardiac tissues of db/db mice. The S-sulfhydration of Hrd1 by NaHS enhanced the interaction between Hrd1 and DGAT1 and 2 to inhibit the formation of LD. Our findings suggested that H₂ S modified Hrd1 S-sulfhydration at Cys115 to reduce the accumulation of LDs in cardiac tissues of db/db mice.

The Hidden Role of Hydrogen Sulfide Metabolism in Cancer

Hydrogen Sulfide (H₂S), an endogenously produced gasotransmitter, is involved in various important physiological and disease conditions, including vasodilation, stimulation of cellular bioenergetics, anti-inflammation, and pro-angiogenesis. In cancer, aberrant up-regulation of H₂S-producing enzymes is frequently observed in different cancer types. The recognition that tumor-derived H₂S plays various roles during cancer development reveals opportunities to target H₂S-mediated signaling pathways in cancer therapy. In this review, we will focus on the mechanism of H₂S-mediated protein persulfidation and the detailed information about the dysregulation of H₂S-producing enzymes and metabolism in different cancer types. We will also provide an update on mechanisms of H₂S-mediated cancer progression and summarize current options to modulate H₂S production for cancer therapy.

New Targets in Heart Failure Drug Therapy

Despite recent advances in chronic heart failure management (either pharmacological or non-pharmacological), the prognosis of heart failure (HF) patients remains poor. This poor prognosis emphasizes the need for developing novel pathways for testing new HF drugs, beyond neurohumoral and hemodynamic modulation approaches. The development of new drugs for HF therapy must thus necessarily focus on novel approaches such as the direct effect on cardiomyocytes, coronary microcirculation, and myocardial interstitium. This review summarizes principal evidence on new possible pharmacological targets for the treatment of HF patients, mainly focusing on microcirculation, cardiomyocyte, and anti-inflammatory therapy.

Hydrogen Sulfide Restored the Diurnal Variation in Cardiac Function of Aging Mice

The present study was performed to investigate whether H2S could restore the diurnal variation in cardiac function of aging mice and explore the potential mechanisms. We found that ejection fraction (EF) and fractional shortening (FS) in 3-month-old mice exhibited diurnal variations over a 24-hour period. However, the diurnal variations were disrupted in 18-month-old mice, and there was a decline in EF and FS. In addition, the plasma malondialdehyde (MDA) levels were increased, and H2S concentrations and superoxide dismutase (SOD) activities were decreased in 18-month-old mice. Then, CSE KO mice were used to determine if there was a relationship between endogenous H2S and diurnal variations in EF and FS. There was no difference in 12-hour averaged EF and FS between dark and light periods in CSE KO mice accompanying increased MDA levels and decreased SOD activities in plasma, indicating that deficiency of endogenous H2S blunted diurnal variations of cardiac function. To determine whether oxidative stress disrupted the diurnal variations in cardiac function, D-galactose-induced subacute aging mice were employed. After 3-month D-gal treatment, both 12-hour averaged EF and FS in dark or light periods were decreased; meanwhile, there was no difference in 12-hour averaged EF and FS between dark and light periods. After 3-month NaHS treatment in the D-gal group, the plasma MDA levels were decreased and SOD activities were increased. The EF and FS were lower during the 12-hour light period than those during the 12-hour dark period which was fit to sine curves in the D-gal+NaHS group. Identical findings were also observed in 18-month-old mice. In conclusion, our studies revealed that the disrupted diurnal variation in cardiac function was associated with increased oxidative stress and decreased H2S levels in aging mice. H2S could restore the diurnal variation in cardiac function of aging mice by reducing oxidative stress.

A Common Molecular Switch for H2S to Regulate Multiple Protein Targets

Hydrogen sulfide, a small molecule, produced by endogenous enzymes, such as CTH, CBS, and MPST using L-cysteine as substrates, has been reported to have numerous protective effects. However, the key problem that the target of H₂S and how it can affect the structure and activity of biological molecules is still unknown. Till now, there are two main theories of its working mechanism. One is that H₂S can modify the free thiol in cysteine to produce the persulfide state of the thiol and the sulfhydration of cysteine can significantly change the structure and activity of target proteins. The other theory is that H₂S, as an antioxidant molecule, can directly break the disulfide bond in target proteins, and the persulfide state of thiol can be an intermediate product during the reaction. Both phenomena exit for no doubt since they are both supported by large amounts of experiments. Here, we will summarize both theories and try to discuss which one is the more effective or direct mechanism for H₂S and what is the relationship between them. Therefore, we will discover more protein targets of H₂S with the mechanism and understand more about the effect of this small molecule.

Persulfidation of transcription factor FOXO1 at cysteine 457: A novel mechanism by which H2S inhibits vascular smooth muscle cell proliferation

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FOXO1 is involved in the inhibitory effect of H₂S on vascular smooth muscle cell proliferation.

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H₂S inhibits vascular smooth muscle cell proliferation by maintaining FOXO1 activity.

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H₂S preserves FOXO1 activity by persulfidation.

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H₂S persulfidates FOXO1 at Cys457 and subsequently prevents FOXO1 phosphorylation at Ser256.

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The results provide new ideas for therapeutic strategies for anti-vascular remodeling.

Introduction

The proliferation of vascular smooth muscle cells (VSMCs) is an important physiological and pathological basis for many cardiovascular diseases. Endogenous hydrogen sulfide (H₂S), the third gasotransmitter, is found to preserve vascular structure by inhibiting VSMC proliferation. However, the mechanism by which H₂S suppresses VSMC proliferation has not been fully clear.

Objectives

This study aimed to explore whether H₂S persulfidates the transcription factor FOXO1 to inhibit VSMC proliferation.

Methods

After the proliferation of VSMC A7r5 cells was induced by endothelin-1 (ET-1), FOXO1 phosphorylation and proliferating cell nuclear antigen (PCNA) expression were detected by Western blotting, the degree of FOXO1 nuclear exclusion and PCNA fluorescent signals in the nucleus were detected by immunofluorescence, and the persulfidation of FOXO1 was measured through a biotin switch assay.

Results

The results showed that ET-1 stimulation increased cell proliferation, FOXO1 phosphorylation and FOXO1 nuclear exclusion to the cytoplasm in the cells. However, pretreatment with NaHS, an H₂S donor, successfully abolished the ET-1-induced increases in the VSMC proliferation, FOXO1 phosphorylation, and FOXO1 nuclear exclusion to the cytoplasm. Mechanistically, H₂S persulfidated the FOXO1 protein in A7r5 and 293T cells, and the thiol reductant DTT reversed this effect. Furthermore, the C457S mutation of FOXO1 abolished the H₂S-induced persulfidation of FOXO1 in the cells and the subsequent inhibitory effects on FOXO1 phosphorylation at Ser256, FOXO1 nuclear exclusion to the cytoplasm and cell proliferation.

Conclusion

Thus, our findings demonstrated that H₂S might inhibit VSMC proliferation by persulfidating FOXO1 at Cys457 and subsequently preventing FOXO1 phosphorylation at Ser256.

Decreased bioavailability of hydrogen sulfide links vascular endothelium and atrial remodeling in atrial fibrillation

Oxidative stress drives the pathogenesis of atrial fibrillation (AF), the most common arrhythmia. In the cardiovascular system, cystathionine γ-lyase (CSE) serves as the primary enzyme producing hydrogen sulfide (H₂S), a mammalian gasotransmitter that reduces oxidative stress. Using a case control study design in patients with and without AF and a mouse model of CSE knockout (CSE-KO), we evaluated the role of H₂S in the etiology of AF. Patients with AF (n = 51) had significantly reduced plasma acid labile sulfide levels compared to patients without AF (n = 65). In addition, patients with persistent AF (n = 25) showed lower plasma free sulfide levels compared to patients with paroxysmal AF (n = 26). Consistent with an important role for H₂S in AF, CSE-KO mice had decreased atrial sulfide levels, increased atrial superoxide levels, and enhanced propensity for induced persistent AF compared to wild type (WT) mice. Rescuing H₂S signaling in CSE-KO mice by Diallyl trisulfide (DATS) supplementation or reconstitution with endothelial cell specific CSE over-expression significantly reduced atrial superoxide, increased sulfide levels, and lowered AF inducibility. Lastly, low H₂S levels in CSE KO mice was associated with atrial electrical remodeling including longer effective refractory periods, slower conduction velocity, increased myocyte calcium sparks, and increased myocyte action potential duration that were reversed by DATS supplementation or endothelial CSE overexpression. Our findings demonstrate an important role of CSE and H₂S bioavailability in regulating electrical remodeling and susceptibility to AF.

Mitochondria-Targeted Drug Delivery in Cardiovascular Disease: A Long Road to Nano-Cardio Medicine

Cardiovascular disease (CVD) represents a major threat for human health. The available preventive and treatment interventions are insufficient to revert the underlying pathological processes, which underscores the urgency of alternative approaches. Mitochondria dysfunction plays a key role in the etiopathogenesis of CVD and is regarded as an intriguing target for the development of innovative therapies. Oxidative stress, mitochondrial permeability transition pore opening, and excessive fission are major noxious pathways amenable to drug therapy. Thanks to the advancements of nanotechnology research, several mitochondria-targeted drug delivery systems (DDS) have been optimized with improved pharmacokinetic and biocompatibility, and lower toxicity and antigenicity for application in the cardiovascular field. This review summarizes the recent progress and remaining obstacles in targeting mitochondria as a novel therapeutic option for CVD. The advantages of nanoparticle delivery over un-targeted strategies are also discussed.

Effects of hydrogen sulfide on mitochondrial function and cellular bioenergetics

Hydrogen sulfide (H₂S) was once considered to have only toxic properties, until it was discovered to be an endogenous signaling molecule. The effects of H₂S are dose dependent, with lower concentrations being beneficial and higher concentrations, cytotoxic. This scenario is especially true for the effects of H₂S on mitochondrial function, where higher concentrations of the gasotransmitter inhibit the electron transport chain, and lower concentrations stimulate bioenergetics in multiple ways. Here we review the role of H₂S in mitochondrial function and its effects on cellular physiology.

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Hydrogen sulfide (H₂S) plays central roles in mitochondrial homeostasis.

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Both excess H₂S and a paucity of H₂S have deleterious effects.

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One of the modes by which H₂S signals in mitochondria is by sulfhydrating target proteins.

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Administering H₂S (where scarcity of H₂S occurs) or inhibiting H₂S production (in case of excess H₂S) may be beneficial.

Cardioprotective Role of Melatonin in Acute Myocardial Infarction

Melatonin is a pleiotropic, indole secreted, and synthesized by the human pineal gland. Melatonin has biological effects including anti-apoptosis, protecting mitochondria, anti-oxidation, anti-inflammation, and stimulating target cells to secrete cytokines. Its protective effect on cardiomyocytes in acute myocardial infarction (AMI) has caused widespread interest in the actions of this molecule. The effects of melatonin against oxidative stress, promoting autophagic repair of cells, regulating immune and inflammatory responses, enhancing mitochondrial function, and relieving endoplasmic reticulum stress, play crucial roles in protecting cardiomyocytes from infarction. Mitochondrial apoptosis and dysfunction are common occurrence in cardiomyocyte injury after myocardial infarction. This review focuses on the targets of melatonin in protecting cardiomyocytes in AMI, the main molecular signaling pathways that melatonin influences in its endogenous protective role in myocardial infarction, and the developmental prospect of melatonin in myocardial infarction treatment.

New insights into the role of mitochondria in cardiac microvascular ischemia/reperfusion injury

As reperfusion therapies have become more widely used in acute myocardial infarction patients, ischemia-induced myocardial damage has been markedly reduced, but reperfusion-induced cardiac injury has become increasingly evident. The features of cardiac ischemia-reperfusion (I/R) injury include microvascular perfusion defects, platelet activation and sequential cardiomyocyte death due to additional ischemic events at the reperfusion stage. Microvascular obstruction, defined as a no-reflow phenomenon, determines the infarct zone, myocardial function and peri-operative mortality. Cardiac microvascular endothelial cell injury may occur much earlier and with much greater severity than cardiomyocyte injury. Endothelial cells contain fewer mitochondria than other cardiac cells, and several of the pathological alterations during cardiac microvascular I/R injury involve mitochondria, such as increased mitochondrial reactive oxygen species (mROS) levels and disturbed mitochondrial dynamics. Although mROS are necessary physiological second messengers, high mROS levels induce oxidative stress, endothelial senescence and apoptosis. Mitochondrial dynamics, including fission, fusion and mitophagy, determine the shape, distribution, size and function of mitochondria. These adaptive responses modify extracellular signals and orchestrate intracellular processes such as cell proliferation, migration, metabolism, angiogenesis, permeability transition, adhesive molecule expression, endothelial barrier function and anticoagulation. In this review, we discuss the involvement of mROS and mitochondrial morphofunction in cardiac microvascular I/R injury.

Hydrogen Sulfide as a Potential Alternative for the Treatment of Myocardial Fibrosis

Harmful, stressful conditions or events in the cardiovascular system result in cellular damage, inflammation, and fibrosis. Currently, there is no targeted therapy for myocardial fibrosis, which is highly associated with a large number of cardiovascular diseases and can lead to fatal heart failure. Hydrogen sulfide (H₂S) is an endogenous gasotransmitter similar to nitric oxide and carbon monoxide. H₂S is involved in the suppression of oxidative stress, inflammation, and cellular death in the cardiovascular system. The level of H₂S in the body can be boosted by stimulating its synthesis or supplying it exogenously with a simple H₂S donor with a rapid- or slow-releasing mode, an organosulfur compound, or a hybrid with known drugs (e.g., aspirin). Hypertension, myocardial infarction, and inflammation are exaggerated when H₂S is reduced. In addition, the exogenous delivery of H₂S mitigates myocardial fibrosis caused by various pathological conditions, such as a myocardial infarct, hypertension, diabetes, or excessive β-adrenergic stimulation, via its involvement in a variety of signaling pathways. Numerous experimental findings suggest that H₂S may work as a potential alternative for the management of myocardial fibrosis. In this review, the antifibrosis role of H₂S is briefly addressed in order to gain insight into the development of novel strategies for the treatment of myocardial fibrosis.

Pathological Roles of Mitochondrial Oxidative Stress and Mitochondrial Dynamics in Cardiac Microvascular Ischemia/Reperfusion Injury

Mitochondria are key regulators of cell fate through controlling ATP generation and releasing pro-apoptotic factors. Cardiac ischemia/reperfusion (I/R) injury to the coronary microcirculation has manifestations ranging in severity from reversible edema to interstitial hemorrhage. A number of mechanisms have been proposed to explain the cardiac microvascular I/R injury including edema, impaired vasomotion, coronary microembolization, and capillary destruction. In contrast to their role in cell types with higher energy demands, mitochondria in endothelial cells primarily function in signaling cellular responses to environmental cues. It is clear that abnormal mitochondrial signatures, including mitochondrial oxidative stress, mitochondrial fission, mitochondrial fusion, and mitophagy, play a substantial role in endothelial cell function. While the pathogenic role of each of these mitochondrial alterations in the endothelial cells I/R injury remains complex, profiling of mitochondrial oxidative stress and mitochondrial dynamics in endothelial cell dysfunction may offer promising potential targets in the search for novel diagnostics and therapeutics in cardiac microvascular I/R injury. The objective of this review is to discuss the role of mitochondrial oxidative stress on cardiac microvascular endothelial cells dysfunction. Mitochondrial dynamics, including mitochondrial fission and fusion, are critically discussed to understand their roles in endothelial cell survival. Finally, mitophagy, as a degradative mechanism for damaged mitochondria, is summarized to figure out its contribution to the progression of microvascular I/R injury.

BRD4 blockage alleviates pathological cardiac hypertrophy through the suppression of fibrosis and inflammation via reducing ROS generation

Hypertension is an essential regulator of cardiac injury and remodeling. However, the pathogenesis that contributes to cardiac hypertrophy remains to be fully explored. BRD4, as a bromodomain and extra-terminal (BET) family member, plays an important role in critical biological processes. In the study, our results showed that BRD4 expression was up-regulated in human and mouse hypertrophied hearts, and importantly these effects were modulated by reactive oxygen species (ROS) generation. In angiotensin II (Ang II)-treated cardiomyocytes, BRD4 decrease markedly blunted the prohypertrophic effect, which was further promoted by the combinational treatment of ROS scavenger (N-acetyl-cysteine, NAC). In addition, NAC pre-treatment markedly elevated the anti-fibrotic role of BRD4 suppression in Ang II-incubated cardiomyocytes by repressing transforming growth factor β1 (TGF-β1)/SMADs signaling pathway. NAC combined with BRD4 reduction further alleviated inflammation and oxidative stress in Ang II-exposed cardiomyocytes, which was partly through inhibiting nuclear factor-κB (NF-κB) signaling and improving nuclear erythroid factor 2-related factor 2 (Nrf-2)/heme oxygenase-1 (HO-1) pathway, respectively. Furthermore, the in vivo results confirmed the protective effects of BRD4 suppression on mice against aortic banding (AB)-induced cardiac hypertrophy, as evidenced by the reduced cross sectional area and fibrotic area using H&E and Masson trichrome staining. What's more, the degree of cardiac hypertrophy (ANP and BNP), the expression of pro-fibrotic genes (TGF-β1, Collagen I, Collagen III and CTGF), the levels of inflammation and oxidative stress were all significantly attenuated by the blockage of BRD4 in AB-operated mice. Taken together, repressing BRD4 expression was found to confer a protective effect against experimental cardiac hypertrophy in mice, demonstrating its potential as an effective therapeutic target for pathological cardiac hypertrophy.

An Appraisal of Developments in Allium Sulfur Chemistry: Expanding the Pharmacopeia of Garlic

Alliums and allied plant species are rich sources of sulfur compounds that have effects on vascular homeostasis and the control of metabolic systems linked to nutrient metabolism in mammals. In view of the multiple biological effects ascribed to these sulfur molecules, researchers are now using these compounds as inspiration for the synthesis and development of novel sulfur-based therapeutics. This research has led to the chemical synthesis and biological assessment of a diverse array of sulfur compounds representative of derivatives of S-alkenyl-l-cysteine sulfoxides, thiosulfinates, ajoene molecules, sulfides, and S-allylcysteine. Many of these synthetic derivatives have potent antimicrobial and anticancer properties when tested in preclinical models of disease. Therefore, the current review provides an overview of advances in the development and biological assessment of synthetic analogs of allium-derived sulfur compounds.

Macrophage autophagy regulates mitochondria-mediated apoptosis and inhibits necrotic core formation in vulnerable plaques

The vulnerable plaque is a key distinguishing feature of atherosclerotic lesions that can cause acute atherothrombotic vascular disease. This study was designed to explore the effect of autophagy on mitochondria-mediated macrophage apoptosis and vulnerable plaques. Here, we generated the mouse model of vulnerable carotid plaque in ApoE^-/- mice. Application of ApoE^-/- mice with rapamycin (an autophagy inducer) inhibited necrotic core formation in vulnerable plaques by decreasing macrophage apoptosis. However, 3-methyladenine (an autophagy inhibitor) promoted plaque vulnerability through deteriorating these indexes. To further explore the mechanism of autophagy on macrophage apoptosis, we used macrophage apoptosis model in vitro and found that 7-ketocholesterol (7-KC, one of the primary oxysterols in oxLDL) caused macrophage apoptosis with concomitant impairment of mitochondria, characterized by the impairment of mitochondrial ultrastructure, cytochrome c release, mitochondrial potential dissipation, mitochondrial fragmentation, excessive ROS generation and both caspase-9 and caspase-3 activation. Interestingly, such mitochondrial apoptotic responses were ameliorated by autophagy activator, but exacerbated by autophagy inhibitor. Finally, we found that MAPK-NF-κB signalling pathway was involved in autophagy modulation of 7-KC-induced macrophage apoptosis. So, we provide strong evidence for the potential therapeutic benefit of macrophage autophagy in regulating mitochondria-mediated apoptosis and inhibiting necrotic core formation in vulnerable plaques.

ZYZ-803 Mitigates Endoplasmic Reticulum Stress-Related Necroptosis after Acute Myocardial Infarction through Downregulating the RIP3-CaMKII Signaling Pathway

Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide, and both cardiac necroptosis and endoplasmic reticulum stress (ERS) have been involved in the pathophysiology of AMI. ZYZ-803 is a hybrid molecule of a dual donor for gasotransmitters H₂S and NO. The aim of the present study is to investigate the antinecroptosis role and potential mechanisms of ZYZ-803 in the setting of ERS during AMI injury. In vivo, ZYZ-803 preserves cardiac function and reduces infarct size significantly after 24-hour left coronary artery ligation through revising H₂S and NO imbalance. In addition, ZYZ-803 relieves ERS and necroptosis in an AMI heart. In vitro, ZYZ-803 ameliorates ERS-related necroptosis induced by tunicamycin, and such effect has been depending on the receptor-interacting protein 3- (RIP3-) Ca²⁺-calmodulin-dependent protein kinase (CaMKII) signaling pathway. These findings have identified a novel antinecroptosis potential of ZYZ-803, providing a valuable candidate for cardioprotection in acute myocardial ischemia.