Protective Actions of H2S in Acute Myocardial Infarction and Heart Failure

Chemoselective Proteomics, Zinc Fingers, and a Zinc(II) Model for H2S Mediated Persulfidation

The gasotransmitter hydrogen sulfide (H2S) is thought to be involved in the post-translational modification of cysteine residues to produce reactive persulfides. A persulfide-specific chemoselective proteomics approach with mammalian cells has identified a broad range of zinc finger (ZF) proteins as targets of persulfidation. Parallel studies with isolated ZFs show that persulfidation is mediated by ZnII, O2, and H2S, with intermediates involving oxygen- and sulfur-based radicals detected by mass spectrometry and optical spectroscopies. A small molecule ZnII complex exhibits analogous reactivity with H2S and O2, giving a persulfidated product. These data show that ZnII is not just a biological structural element, but also plays a critical role in mediating H2S-dependent persulfidation. ZF persulfidation appears to be a general post-translational modification and a possible conduit for H2S signaling. This work has implications for our understanding of H2S-mediated signaling and the regulation of ZFs in cellular physiology and development.

Harnessing Mitochondrial Stress for Health and Disease: Opportunities and Challenges

Mitochondria, essential organelles orchestrating cellular metabolism, have emerged as central players in various disease pathologies. Recent research has shed light on mitohormesis, a concept proposing an adaptive response of mitochondria to minor disturbances in homeostasis, offering novel therapeutic avenues for mitochondria-related diseases. This comprehensive review explores the concept of mitohormesis, elucidating its induction mechanisms and occurrence. Intracellular molecules like reactive oxygen species (ROS), calcium, mitochondrial unfolded proteins (UPRmt), and integrated stress response (ISR), along with external factors such as hydrogen sulfide (H2S), physical stimuli, and exercise, play pivotal roles in regulating mitohormesis. Based on the available evidence, we elucidate how mitohormesis maintains mitochondrial homeostasis through mechanisms like mitochondrial quality control and mitophagy. Furthermore, the regulatory role of mitohormesis in mitochondria-related diseases is discussed. By envisioning future applications, this review underscores the significance of mitohormesis as a potential therapeutic target, paving the way for innovative interventions in disease management.

Using mechanism-based combinations of H2S-donors to maximize the cardioprotective action of H2S

H2S-donors are cardioprotective in ischemia/reperfusion (I/R) injury. Some H2S-donors exert their beneficial effects in a nitric oxide (NO)-dependent manner, while others act using NO-independent pathways. The aims of the present study were to (i) evaluate whether H2S-donors with distinct pharmacodynamic properties act synergistically in I/R injury and (ii) determine if H2S-donors remain cardioprotective in obese mice. C57BL/6 mice were subjected to 30 min of ischemia followed by 120 min of reperfusion. Donors were administered intravenously at the end of ischemia (Na2S: 1 μmol/kg, GYY4137: 25 μmol/kg, AP39: 0,25 μmol/kg), while the 3-mercaptopyruvate sulfurtransferase (10 mg/kg) inhibitor was given intraperitonially 1 h prior to ischemia. Infarct size was estimated by 2,3,5-triphenyltetrazolium staining, while the area at risk was calculated using Evans blue. All three donors reduced infarct size when administered as a sole treatment. Co-administration of Na2S/GYY4137, as well as Na2S/AP39 reduced further the I/R injury, beyond what was observed with each individual donor. Since inhibition of the H2S-producing enzyme 3-mercaptopyruvate sulfurtransferase is known to reduce infarct size, we co-administered C3 with Na2S to determine possible additive effects between the two agents. In this case, combination of C3 with Na2S did not yield superior results compared to the individual treatments. Similarly, to what was observed in healthy mice, administration of a H2S-donor (Na2S or AP39) reduced I/R injury in mice rendered obese by consumption of a high fat diet. We conclude that combining a NO-dependent with a NO-independent H2S-donor leads to enhanced cardioprotection and that H2S-donors remain effective in obese animals.

Therapeutic potential of hydrogen sulfide in osteoarthritis development

The pathological mechanisms and treatments of osteoarthritis (OA) are critical topics in medical research. This paper reviews the regulatory mechanisms of hydrogen sulfide (H2S) in OA and the therapeutic potential of H2S donors. The review highlights the importance of changes in the endogenous H2S pathway in OA development and systematically elaborates on the role of H2S as a third gaseous transmitter that regulates inflammation, oxidative stress, and pain associated with OA. It also explains how H2S can lessen bone and joint inflammation by inhibiting leukocyte adhesion and migration, reducing pro-inflammatory mediators, and impeding the activation of key inflammatory pathways such as nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK). Additionally, H2S is shown to mitigate mitochondrial dysfunction and endoplasmic reticulum stress, and to modulate Nrf2, NF-κB, PI3K/Akt, and MAPK pathways, thereby decreasing oxidative stress-induced chondrocyte apoptosis. Moreover, H2S alleviates bone and joint pain through the activation of Kv7, K-ATP, and Nrf2/HO-1-NQO1 pathways. Recent developments have produced a variety of H2S donors, including sustained-release H2S donors, natural H2S donors, and synthetic H2S donors. Understanding the role of H2S in OA can lead to the discovery of new therapeutic targets, while innovative H2S donors offer promising new treatments for patients with OA.

Hydrogen Sulfide Promotes Postnatal Cardiomyocyte Proliferation by Upregulating SIRT1 Signaling Pathway

Hydrogen sulfide (H2S) has been identified as a novel gasotransmitter and a substantial antioxidant that can activate various cellular targets to regulate physiological and pathological processes in mammals. However, under physiological conditions, it remains unclear whether it is involved in regulating cardiomyocyte (CM) proliferation during postnatal development in mice. This study mainly aimed to evaluate the role of H2S in postnatal CM proliferation and its regulating molecular mechanisms. We found that sodium hydrosulfide (NaHS, the most widely used H2S donor, 50-200 μM) increased neonatal mouse primary CM proliferation in a dose-dependent manner in vitro. Consistently, exogenous administration of H2S also promoted CM proliferation and increased the total number of CMs at postnatal 7 and 14 days in vivo. Moreover, we observed that the protein expression of SIRT1 was significantly upregulated after NaHS treatment. Inhibition of SIRT1 with EX-527 or si-SIRT1 decreased CM proliferation, while enhancement of the activation of SIRT1 with SRT1720 promoted CM proliferation. Meanwhile, pharmacological and genetic blocking of SIRT1 repressed the effect of NaHS on CM proliferation. Taken together, these results reveal that H2S plays a promotional role in proliferation of CMs in vivo and in vitro and SIRT1 is required for H2S-mediated CM proliferation, which indicates that H2S may be a potential modulator for heart development in postnatal time window.

Attenuation of Sepsis-Induced Acute Kidney Injury by Exogenous H2S via Inhibition of Ferroptosis

Sepsis-associated acute kidney injury (SA-AKI) results in significant morbidity and mortality, and ferroptosis may play a role in its pathogenesis. Our aim was to examine the effect of exogenous H₂S (GYY4137) on ferroptosis and AKI in in vivo and in vitro models of sepsis and explore the possible mechanism involved. Sepsis was induced by cecal ligation and puncture (CLP) in male C57BL/6 mice, which were randomly divided into the sham, CLP, and CLP + GYY4137 group. The indicators of SA-AKI were most prominent at 24 h after CLP, and analysis of the protein expression of ferroptosis indicators showed that ferroptosis was also exacerbated at 24 h after CLP. Moreover, the level of the endogenous H₂S synthase CSE (Cystathionine-γ-lyase) and endogenous H₂S significantly decreased after CLP. Treatment with GYY4137 reversed or attenuated all these changes. In the in vitro experiments, LPS was used to simulate SA-AKI in mouse renal glomerular endothelial cells (MRGECs). Measurement of ferroptosis-related markers and products of mitochondrial oxidative stress showed that GYY4137 could attenuate ferroptosis and regulate mitochondrial oxidative stress. These findings imply that GYY4137 alleviates SA-AKI by inhibiting ferroptosis triggered by excessive mitochondrial oxidative stress. Thus, GYY4137 may be an effective drug for the clinical treatment of SA-AKI.

Advances of H2S in Regulating Neurodegenerative Diseases by Preserving Mitochondria Function

Neurotoxicity is induced by different toxic substances, including environmental chemicals, drugs, and pathogenic toxins, resulting in oxidative damage and neurodegeneration in mammals. The nervous system is extremely vulnerable to oxidative stress because of its high oxygen demand. Mitochondria are the main source of ATP production in the brain neuron, and oxidative stress-caused mitochondrial dysfunction is implicated in neurodegenerative diseases. H2S was initially identified as a toxic gas; however, more recently, it has been recognized as a neuromodulator as well as a neuroprotectant. Specifically, it modulates mitochondrial activity, and H2S oxidation in mitochondria produces various reactive sulfur species, thus modifying proteins through sulfhydration. This review focused on highlighting the neuron modulation role of H2S in regulating neurodegenerative diseases through anti-oxidative, anti-inflammatory, anti-apoptotic and S-sulfhydration, and emphasized the importance of H2S as a therapeutic molecule for neurological diseases.

CTH G1208T and MTHFR A1298C polymorphisms are associated with a higher risk of a first myocardial infarction with fatal outcome among women

OBJECTIVES

Cystathionine-gamma-lyase (CSE) in the transsulfuration pathway generates hydrogen sulfide (H₂S), suggested regulating cardiovascular function. The G1208T polymorphism in the CTH gene, rs1021737, has, in addition to MTHFR, been found to increase homocysteine, related to myocardial infarction (MI) risk. This study aimed, for the first time, to investigate the associations of the polymorphisms CTH G1208T, MTHFR C677T, and A1298C with the prospective risk of developing a fatal or non-fatal first MI.

METHODS

This case-referent study included 545 cases later developing a first-ever MI and 1,054 referents from the Northern Sweden Health and Disease Study. Fatal MI was defined as death within 28 days after MI symptoms.

RESULTS

Women, but not men, had a positive association between fatal MI and the CTH G1208T, odds ratio [95% confidence interval] 3.14 [1.16-8.54] for heterozygotes, and the dominant model 3.22 [1.22-8.51], and for the MTHFR A1298C heterozygotes 3.24 [1.26-8.34] and the dominant model 2.63 [1.06-6.50]. The MTHFR C677T polymorphism was not related to MI.

CONCLUSIONS

This study indicates that the minor alleles of CTH G1208T and MTHFR A1298C polymorphisms are associated with a higher risk for a fatal MI among women but not for non-fatal MI. No association was found in men.

CTH/MPST double ablation results in enhanced vasorelaxation and reduced blood pressure via upregulation of the eNOS/sGC pathway

Hydrogen sulfide (H₂S), a gasotransmitter with protective effects in the cardiovascular system, is endogenously generated by three main enzymatic pathways: cystathionine gamma lyase (CTH), cystathionine beta synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (MPST) enzymes. CTH and MPST are the predominant sources of H₂S in the heart and blood vessels, exhibiting distinct effects in the cardiovascular system. To better understand the impact of H₂S in cardiovascular homeostasis, we generated a double Cth/Mpst knockout (Cth/Mpst ^-/- ) mouse and characterized its cardiovascular phenotype. CTH/MPST-deficient mice were viable, fertile and exhibited no gross abnormalities. Lack of both CTH and MPST did not affect the levels of CBS and H₂S-degrading enzymes in the heart and the aorta. Cth/Mpst ^-/- mice also exhibited reduced systolic, diastolic and mean arterial blood pressure, and presented normal left ventricular structure and fraction. Aortic ring relaxation in response to exogenously applied H₂S was similar between the two genotypes. Interestingly, an enhanced endothelium-dependent relaxation to acetylcholine was observed in mice in which both enzymes were deleted. This paradoxical change was associated with upregulated levels of endothelial nitric oxide synthase (eNOS) and soluble guanylate cyclase (sGC) α1 and β1 subunits and increased NO-donor-induced vasorelaxation. Administration of a NOS-inhibitor, increased mean arterial blood pressure to a similar extent in wild-type and Cth/Mpst ^-/- mice. We conclude that chronic elimination of the two major H₂S sources in the cardiovascular system, leads to an adaptive upregulation of eNOS/sGC signaling, revealing novel ways through which H₂S affects the NO/cGMP pathway.

Hydrogen sulfide and its donors: Novel antitumor and antimetastatic agents for liver cancer

Hepatocellular carcinoma (HCC) is the sixth most frequent human cancer and the world's third most significant cause of cancer mortality. HCC treatment has recently improved, but its mortality continues to increase worldwide due to its extremely complicated and heterogeneous genetic abnormalities. After nitric oxide (NO) and carbon monoxide (CO), the third gas signaling molecule discovered is hydrogen sulfide (H₂S), which has long been thought to be a toxic gas. However, numerous studies have proven that H₂S plays many pathophysiological roles in mammals. Endogenous or exogenous H₂S can decrease cell proliferation, promote apoptosis, block cell cycle, invasion and migration through various cellular signaling pathways. This review analyzes and discusses the recent literature on the function and molecular mechanism of H₂S and H₂S donors in HCC, so as to provide convenience for the scientific research and clinical application of H₂S in the treatment of liver cancer.

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.

The Role of Hydrogen Sulfide in the Development and Progression of Lung Cancer

Lung cancer is one of the 10 most common cancers in the world, which seriously affects the normal life and health of patients. According to the investigation report, the 3-year survival rate of patients with lung cancer is less than 20%. Heredity, the environment, and long-term smoking or secondhand smoke greatly promote the development and progress of the disease. The mechanisms of action of the occurrence and development of lung cancer have not been fully clarified. As a new type of gas signal molecule, hydrogen sulfide (H₂S) has received great attention for its physiological and pathological roles in mammalian cells. It has been found that H₂S is widely involved in the regulation of the respiratory system and digestive system, and plays an important role in the occurrence and development of lung cancer. H₂S has the characteristics of dissolving in water and passing through the cell membrane, and is widely expressed in body tissues, which determines the possibility of its participation in the occurrence of lung cancer. Both endogenous and exogenous H₂S may be involved in the inhibition of lung cancer cells by regulating mitochondrial energy metabolism, mitochondrial DNA integrity, and phosphoinositide 3-kinase/protein kinase B co-pathway hypoxia-inducible factor-1α (HIF-1α). This article reviews and discusses the molecular mechanism of H₂S in the development of lung cancer, and provides novel insights for the prevention and targeted therapy of lung cancer.

Hydrogen sulfide protects against ischemic heart failure by inhibiting RIP1/RIP3/MLKL-mediated necroptosis

The aim of the present study was to explore whether hydrogen sulfide (H2S) protects against ischemic heart failure (HF) by inhibiting the necroptosis pathway. Mice were randomized into Sham, myocardial infarction (MI), MI + propargylglycine (PAG) and MI + sodium hydrosulfide (NaHS) group, respectively. The MI model was induced by ligating the left anterior descending coronary artery. PAG was intraperitoneally administered at a dose of 50 mg/kg/day for 4 weeks, and NaHS at a dose of 4mg/kg/day for the same period. At 4 weeks after MI, the following were observed: A significant decrease in the cardiac function, as evidenced by a decline in ejection fraction (EF) and fractional shortening (FS); an increase in plasma myocardial injury markers, such as creatine kinase-MB (CK-MB) and cardiac troponin I (cTNI); an increase in myocardial collagen content in the heart tissues; and a decrease of H2S level in plasma and heart tissues. Furthermore, the expression levels of necroptosis-related markers such as receptor interacting protein kinase 1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL) were upregulated after MI. NaHS treatment increased H2S levels in plasma and heart tissues, preserving the cardiac function by increasing EF and FS, decreasing plasma CK-MB and cTNI and reducing collagen content. Additionally, NaHS treatment significantly downregulated the RIP1/RIP3/MLKL pathway. While, PAG treatment aggravated cardiac function by activated the RIP1/RIP3/MLKL pathway. Overall, the present study concluded that H2S protected against ischemic HF by inhibiting RIP1/RIP3/MLKL-mediated necroptosis which could be a potential target treatment for ischemic HF.

Role of hydrogen sulphide in physiological and pathological angiogenesis

The role of hydrogen sulphide (H₂ S) in angiogenesis has been widely demonstrated. Vascular endothelial growth factor (VEGF) plays an important role in H₂ S-induced angiogenesis. H₂ S promotes angiogenesis by upregulating VEGF via pro-angiogenic signal transduction. The involved signalling pathways include the mitogen-activated protein kinase pathway, phosphoinositide-3 kinase pathway, nitric oxide (NO) synthase/NO pathway, signal transducer and activator of transcription 3 (STAT3) pathway, and adenosine triphosphate (ATP)-sensitive potassium (K_ATP ) channels. H₂ S has been shown to contribute to tumour angiogenesis, diabetic wound healing, angiogenesis in cardiac and cerebral ischaemic tissues, and physiological angiogenesis during the menstrual cycle and pregnancy. Furthermore, H₂ S can exert an anti-angiogenic effect by inactivating Wnt/β-catenin signalling or blocking the STAT3 pathway in tumours. Therefore, H₂ S plays a double-edged sword role in the process of angiogenesis. The regulation of H₂ S production is a promising therapeutic approach for angiogenesis-associated diseases. Novel H₂ S donors and/or inhibitors can be developed in the treatment of angiogenesis-dependent diseases.

Construction of a Band-Aid Like Cardiac Patch for Myocardial Infarction with Controllable H2 S Release

Excessive or persistent inflammation incites cardiomyocytes necrosis by generating reactive oxygen species in myocardial infarction (MI). Hydrogen sulfide (H₂ S), a gaseous signal molecule, can quickly permeate cells and tissues, growing concerned for its cardioprotective effects. However, short resident time and strong side effects greatly restrict its application. Herein, a complex scaffold (AAB) is first developed to slowly release H₂ S for myocardial protection by integrating alginate modified with 2-aminopyridine-5-thiocarboxamide (H₂ S donor) into albumin electrospun fibers. Next, a band-aid like patch is constructed based on AAB (center) and nanocomposite scaffold which comprises albumin scaffold and black phosphorus nanosheets (BPNSs). With near-infrared laser (808 nm), thermal energy generated by BPNSs can locally change the molecular structure of fibrous scaffold, thereby attaching patch to the myocardium. In this study, it is also demonstrated that AAB can enhance regenerative M2 macrophage and attenuate inflammatory polarization of macrophages via reduction in intracellular ROS. Eventually, this engineered cardiac patch can relieve inflammation and promote angiogenesis after MI, and thereby recover heart function, providing a promising therapeutic strategy for MI treatment.

On-demand therapeutic delivery of hydrogen sulfide aided by biomolecules

Hydrogen sulfide (H₂S), known as the third gasotransmitter, exerts various physiological functions including cardiac protection, angiogenesis, anti-inflammatory, and anti-cancer capability. Given its promising therapeutic potential as well as severe perniciousness if improper use, the sustained and tunable H₂S delivery systems are highly required for H₂S-based gas therapy with enhanced bioactivity and reduced side effects. To this end, a series of stimuli-responsive compounds capable of releasing H₂S (termed H₂S donors) have been designed over the past two decades to mimic the endogenous generation of H₂S and elucidate the biological functions. Further to improve the stability of H₂S donors and achieve the targeted delivery, various delivery systems have been constructed. In this review, we focus on the recent advances of an emerging subset, biomolecular-based H₂S delivery systems, which combine H₂S donors with biomolecular vectors including polysaccharide, peptide, and protein. We demonstrated their basic structures, building strategies, and therapeutic applications respectively to unfold their inherent merits endued by biomolecules including biocompatibility, biodegradability as well as expansibility. The varied development potentials of biomolecular-based H₂S delivery systems based on their specific properties are also discussed. At the end, brief future outlooks and upcoming challenges are presented as well.

The oral microbiota and cardiometabolic health: A comprehensive review and emerging insights

There is mounting evidence demonstrating that oral dysbiosis causes periodontal disease and promotes the development of cardiovascular disease. The advancement of omics techniques has driven the optimization of oral microbiota species analysis and has provided a deeper understanding of oral pathogenic bacteria. A bi-directional relationship exists between the oral microbiota and the host, and oral-gut microbiota transfer is known to alter the composition of the gut microbiota and may cause local metabolic disorders. Furthermore, cardiovascular health can also be highly affected by oral microbiota functions and metabolites, including short-chain fatty acids (SCFAs), nitric oxide (NO), hydrogen sulfide (H2S), and some lipid metabolites. Studies have found that trimethylamine oxide (TMAO) may have adverse effects on cardiovascular health, whereas SCFAs, NO, and H2S have cardioprotective effects. SCFAs and H2S exert varying oral and cardiovascular effects, however reports on this specific topic remain controversial. Previous evidences are accustomed to summarizing the functions of oral microbiota in the context of periodontitis. The direct relationship between oral microbiota and cardiovascular diseases is insufficient. By systematically summarizing the methods associated with oral microbiota transplantation (OMT), this review facilitates an investigation into the causal links between oral microbiota and cardiovascular disease. The concomitant development of omics, bioinformatics, bacterial culture techniques, and microbiota transplantation techniques is required to gain a deeper understanding of the relationship between oral microbiota and cardiovascular disease occurrence.

Homocysteinylation and Sulfhydration in Diseases

Homocysteine (Hcy) is an important intermediate in methionine metabolism and generation of one-carbon units, and its dysfunction is associated with many pathological states. Although Hcy is a non-protein amino acid, many studies have demonstrated protein-related homocysteine metabolism and possible mechanisms underlying homocysteinylation. Homocysteinylated proteins lose their original biological function and have a negative effect on the various disease phenotypes. Hydrogen sulfide (H₂S) has been recognized as an important gaseous signaling molecule with mounting physiological properties. H₂S modifies small molecules and proteins via sulfhydration, which is supposed to be essential in the regulation of biological functions and signal transduction in human health and disorders. This review briefly introduces Hcy and H₂S, further discusses pathophysiological consequences of homocysteine modification and sulfhydryl modification, and ultimately makes a prediction that H₂S might exert a protective effect on the toxicity of homocysteinylation of target protein via sulfhydration. The highlighted information here yields new insights into the role of protein modification by Hcy and H₂S in diseases.

Progress and perspective on hydrogen sulfide donors and their biomedical applications

Following the discovery of nitric oxide (NO) and carbon monoxide (CO), hydrogen sulfide (H₂ S) has been identified as the third gasotransmitter in humans. Increasing evidence have shown that H₂ S is of preventive or therapeutic effects on diverse pathological complications. As a consequence, it is of great significance to develop suitable approaches of H₂ S-based therapeutics for biomedical applications. H₂ S-releasing agents (H₂ S donors) play important roles in exploring and understanding the physiological functions of H₂ S. More importantly, accumulating studies have validated the theranostic potential of H₂ S donors in extensive repertoires of in vitro and in vivo disease models. Thus, it is imperative to summarize and update the literatures in this field. In this review, first, the background of H₂ S on its chemical and biological aspects is concisely introduced. Second, the studies regarding the H₂ S-releasing compounds are categorized and described, and accordingly, their H₂ S-donating mechanisms, biological applications, and therapeutic values are also comprehensively delineated and discussed. Necessary comparisons between related H₂ S donors are presented, and the drawbacks of many typical H₂ S donors are analyzed and revealed. Finally, several critical challenges encountered in the development of multifunctional H₂ S donors are discussed, and the direction of their future development as well as their biomedical applications is proposed. We expect that this review will reach extensive audiences across multiple disciplines and promote the innovation of H₂ S biomedicine.

Hydrogen Sulfide Biology and Its Role in Cancer

Hydrogen sulfide (H₂S) is an endogenous biologically active gas produced in mammalian tissues. It plays a very critical role in many pathophysiological processes in the body. It can be endogenously produced through many enzymes analogous to the cysteine family, while the exogenous source may involve inorganic sulfide salts. H₂S has recently been well investigated with regard to the onset of various carcinogenic diseases such as lung, breast, ovaries, colon cancer, and neurodegenerative disorders. H₂S is considered an oncogenic gas, and a potential therapeutic target for treating and diagnosing cancers, due to its role in mediating the development of tumorigenesis. Here in this review, an in-detail up-to-date explanation of the potential role of H₂S in different malignancies has been reported. The study summarizes the synthesis of H₂S, its roles, signaling routes, expressions, and H₂S release in various malignancies. Considering the critical importance of this active biological molecule, we believe this review in this esteemed journal will highlight the oncogenic role of H₂S in the scientific community.

Isoliquiritigenin Ameliorates Ischemia-Induced Myocardial Injury via Modulating the Nrf2/HO-1 Pathway in Mice

Background

Oxidative stress and inflammatory reaction play critical roles in acute myocardial infarction (AMI). Isoliquiritigenin (ISL), a flavonoid monomer extracted from licorice, has been found to have antioxidant and anti-inflammatory effects in cancer studies. Here, we tested the effect and underlying mechanisms of ISL on ischemia-induced myocardial injury in a mouse AMI model.

Methods

Adult C57BL/6 mice were pre-treated by intraperitoneal injection of ISL and/or a specific nuclear factor E2-related factor 2 (Nrf2) inhibitor ML385 for 3 days, respectively. Then, the AMI model was established by ligating the anterior descending branch of the left coronary artery. Myocardial oxidative stress status, inflammatory response, cardiac function and infarction size were assessed after 7th day of surgery.

Results

Compared with sham group, the reactive oxygen species (ROS) and malondialdehyde (MDA) level in AMI group were significantly increased. However, the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) level were dramatically decreased. ISL treatment significantly reduced the myocardial infarction area, improved cardiac function, inhibited the production of ROS and MDA and reduced the consumption of SOD and GSH-Px. Interestingly, ISL could significantly increase nuclear Nrf2 and cytosolic heme oxygenase 1 (HO-1) level in the infarcted myocardium and reduce the oxidative stress after AMI. Also, ISL treatment dramatically inhibited the activation of myocardial NF-κB pathway and reduced the expression of pro-inflammatory factors in the AMI group. However, the administration of ML385 not only suppressed the Nrf2/HO-1 activation, the anti-oxidant and anti-inflammatory effects induced by ISL, but also attenuated the beneficial role of ISL on reducing infarct size and improving cardiac function in the mouse with AMI.

Conclusion

The results suggested that activation of Nrf2/HO-1 pathway has an essential role in ISL-induced cardiac protection by alleviating myocardial oxidative stress and inflammation response in mice with AMI.

Blue light induces skin apoptosis and degeneration through activation of the endoplasmic reticulum stress-autophagy apoptosis axis: Protective role of hydrogen sulfide

Research on the phototoxicity of blue light (BL) to the skin is increasing. Although blue light can induce oxidative stress, inflammation, and inhibition of proliferation in skin cells, the mechanism by which blue light damages the skin is not yet clear. Endoplasmic reticulum (ER) stress and autophagy are two mechanisms by which cells resist external interference factors and maintain cell homeostasis and normal function, and both can affect cell apoptosis. Interestingly, we have found that blue light (435 nm ~ 445 nm, 8000 lx, 6-24 h)-induced oxidative stress triggers the ER stress-CHOP (C/EBP homologous protein) signal and affects the protein levels of B-cell lymphoma-2 (Bcl-2) and Bcl2-associated X (Bax), thereby promoting apoptosis. In addition, blue light activates autophagy in skin cells, which intensifies cell death. When ER stress is inhibited, autophagy is subsequently inhibited, suggesting that blue light-induced autophagy is influenced by ER stress. These evidences suggest that blue light induces activation of reactive oxygen species (ROS)-ER stress-autophagy-apoptosis axis signaling, which further induces skin injury and apoptosis. This is the first report on the relationships among oxidative stress, ER stress, autophagy, and apoptosis in blue light-induced skin injury. Furthermore, we have studied the effect of hydrogen sulfide (H₂S) on blue light-induced skin damage, and found that exogenous H₂S can protect skin from blue light-induced damage by regulating the ROS-ER stress-autophagy-apoptosis axis. Our data shows that when we are exposed to blue light, such as sunbathing and jaundice treatment, H₂S may be developed as a protective agent.

Hydrogen Sulfide and the Kidney: Physiological Roles, Contribution to Pathophysiology, and Therapeutic Potential

Significance: Hydrogen sulfide (H₂S), the third member of the gasotransmitter family, has a broad spectrum of biological activities, including antioxidant and cytoprotective actions, as well as vasodilatory, anti-inflammatory and antifibrotic effects. New, significant aspects of H₂S biology in the kidney continue to emerge, underscoring the importance of this signaling molecule in kidney homeostasis, function, and disease. Recent Advances: H₂S signals via three main mechanisms, by maintaining redox balance through its antioxidant actions, by post-translational modifications of cellular proteins (S-sulfhydration), and by binding to protein metal centers. Important renal functions such as glomerular filtration, renin release, or sodium reabsorption have been shown to be regulated by H₂S, using either exogenous donors or by the endogenous-producing systems. Critical Issues: Lower H₂S levels are observed in many renal pathologies, including renal ischemia-reperfusion injury and obstructive, diabetic, or hypertensive nephropathy. Unraveling the molecular targets through which H₂S exerts its beneficial effects would be of great importance not only for understanding basic renal physiology, but also for identifying new pharmacological interventions for renal disease. Future Directions: Additional studies are needed to better understand the role of H₂S in the kidney. Mapping the expression pattern of H₂S-producing and -degrading enzymes in renal cells and generation of cell-specific knockout mice based on this information will be invaluable in the effort to unravel additional roles for H₂S in kidney (patho)physiology. With this knowledge, novel targeted more effective therapeutic strategies for renal disease can be designed. Antioxid. Redox Signal. 36, 220-243.

Hydrogen Sulfide Releasing Hydrogel for Alleviating Cardiac Inflammation and Protecting Against Myocardial Ischemia-Reperfusion Injury

Myocardial infarction is one of the leading causes of death worldwide. Thus, protection against myocardial ischemia-reperfusion injury is particularly important to improve the prognosis of myocardial infarction. Recently, hydrogen sulfide...

ADAM and ADAMTS disintegrin and metalloproteinases as major factors and molecular targets in vascular malfunction and disease

A Disintegrin and Metalloproteinase (ADAM) and A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS) are two closely related families of proteolytic enzymes. ADAMs are largely membrane-bound enzymes that act as molecular scissors or sheddases of membrane-bound proteins, growth factors, cytokines, receptors and ligands, whereas ADAMTS are mainly secreted enzymes. ADAMs have a pro-domain, and a metalloproteinase, disintegrin, cysteine-rich and transmembrane domain. Similarly, ADAMTS family members have a pro-domain, and a metalloproteinase, disintegrin, and cysteine-rich domain, but instead of a transmembrane domain they have thrombospondin motifs. Most ADAMs and ADAMTS are activated by pro-protein convertases, and can be regulated by G-protein coupled receptor agonists, Ca²⁺ ionophores and protein kinase C. Activated ADAMs and ADAMTS participate in numerous vascular processes including angiogenesis, vascular smooth muscle cell proliferation and migration, vascular cell apoptosis, cell survival, tissue repair, and wound healing. ADAMs and ADAMTS also play a role in vascular malfunction and cardiovascular diseases such as hypertension, atherosclerosis, coronary artery disease, myocardial infarction, heart failure, peripheral artery disease, and vascular aneurysm. Decreased ADAMTS13 is involved in thrombotic thrombocytopenic purpura and microangiopathies. The activity of ADAMs and ADAMTS can be regulated by endogenous tissue inhibitors of metalloproteinases and other synthetic small molecule inhibitors. ADAMs and ADAMTS can be used as diagnostic biomarkers and molecular targets in cardiovascular disease, and modulators of ADAMs and ADAMTS activity may provide potential new approaches for the management of cardiovascular disorders.

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.

A ROS-responsive, self-immolative and self-reporting hydrogen sulfide donor with multiple biological activities for the treatment of myocardial infarction

Myocardial infarction (MI), as one of the leading causes of global death, urgently needs effective therapies. Recently, hydrogen sulfide (H₂S) has been regarded as a promising therapeutic agent for MI, while its spatiotemporally controlled delivery remains a major issue limiting clinical translation. To address this limitation, we designed and synthesized a novel H₂S donor (HSD-R) that can produce H₂S and emit fluorescence in response to reactive oxygen species (ROS) highly expressed at diseased sites. HSD-R can specifically target mitochondria and provide red fluorescence to visualize and quantify H₂S release in vitro and in vivo. Therapeutically, HSD-R significantly promoted the reconstruction of cardiac structure and function in a rat MI model. Mechanistically, myocardial protection is achieved by reducing cardiomyocyte apoptosis, attenuating local inflammation, and promoting angiogenesis. Furthermore, inhibition of typical pro-apoptotic genes (Bid, Apaf-1, and p53) played an important role in the anti-apoptotic effect of HSD-R to achieve cardioprotection, which were identified as new therapeutic targets of H₂S against myocardial ischemia injury. This ROS-responsive, self-immolative, and fluorescent H₂S donor can serve as a new theranostic agent for MI and other ischemic diseases.

•

A reactive oxygen species-responsive and self-reporting H₂S donor (HSD-R) is developed for controlled H₂S delivery.

•

HSD-R shows desirable fluorescence for imaging H₂S release upon triggering by reactive oxygen species.

•

HSD-R displays significant cardioprotective effects in rats.

•

HSD-R exhibits multiple biological activities including anti-apoptotic, anti-inflammatory, and pro-angiogenic effects.

•

Anti-apoptotic activity of HSD-R is due to inhibiting the expression of several pro-apoptotic factors.

An Updated Insight Into Molecular Mechanism of Hydrogen Sulfide in Cardiomyopathy and Myocardial Ischemia/Reperfusion Injury Under Diabetes

Cardiovascular diseases are the most common complications of diabetes, and diabetic cardiomyopathy is a major cause of people death in diabetes. Molecular, transcriptional, animal, and clinical studies have discovered numerous therapeutic targets or drugs for diabetic cardiomyopathy. Within this, hydrogen sulfide (H₂S), an endogenous gasotransmitter alongside with nitric oxide (NO) and carbon monoxide (CO), is found to play a critical role in diabetic cardiomyopathy. Recently, the protective roles of H₂S in diabetic cardiomyopathy have attracted enormous attention. In addition, H₂S donors confer favorable effects in myocardial infarction, ischaemia-reperfusion injury, and heart failure under diabetic conditions. Further studies have disclosed that multiplex molecular mechanisms are responsible for the protective effects of H₂S against diabetes-elicited cardiac injury, such as anti-oxidative, anti-apoptotic, anti-inflammatory, and anti-necrotic properties. In this review, we will summarize the current findings on H₂S biology and pharmacology, especially focusing on the novel mechanisms of H₂S-based protection against diabetic cardiomyopathy. Also, the potential roles of H₂S in diabetes-aggravated ischaemia-reperfusion injury are discussed.

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.

A simultaneous identification and quantification strategy for determination of sulfhydryl-containing metabolites in normal- and high-fat diet hamsters using stable isotope labeling combined with LC-MS

Sulfur-containing metabolites are related to several physiologic disorders and metabolic diseases. In this study, a simultaneous identification and quantification strategy in one batch for determination of sulfhydryl-containing metabolites was developed using stable isotope labeling combined with liquid chromatography-tandem mass spectrometry (SIL-LC-MS). In the proposed method, a pair of isotope labeling reagents, D₀/D₅-N-ethylmaleimide (D₀/D₅-NEM), was used to derivatize sulfhydryl-containing metabolites in blood and plasma of normal- and high-fat-diet (NFD and HFD) hamsters for reduced (-SH) and total (-SH, -S-S-, S-glutathionylated proteins) analysis. Quality control (QC) samples and test samples were prepared for LC-MS analysis. First, both QC samples and stable isotope labeled internal standards were used to monitor the status of the instrument and ensure the reliability of the analysis. Subsequently, an inhouse database containing 45 sulfhydryl-containing metabolites was established by MS¹ based on QC samples. Then, qualitatively differential sulfhydryl-containing metabolites were found by MS² between the NFD and HFD hamsters of the test samples, including 3 in reduced and 8 in total analysis of blood samples, and 2 in reduced and 2 in total analysis of plasma samples. Next, in quantitative analysis, satisfied linearities for 6 sulfhydryl-containing metabolites were obtained with the correlation coefficient (R²) > 0.99 and absolute quantification was carried out. The results showed that glutathione and cysteine have different concentrations in blood and plasma of hamsters. Finally, the correlation of sulfhydryl-containing metabolites with blood lipid and oxidative stress levels was determined, which provided insight into the hyperlipidemia-related oxidative stress. Taken together, the developed method of simultaneous identification with the inhouse database and MS² and quantification with standards in one batch provides a promising strategy for the analysis of sulfhydryl-containing metabolites in biological samples, which may promote the in-depth investigation on sulfhydryl-containing metabolites and related diseases.

Amino acid-based H2S donors: N-thiocarboxyanhydrides that release H2S with innocuous byproducts

A library of N-thiocarboxyanhydrides (NTAs) derived from natural amino acids with benign byproducts and controlled H2S-release kinetics is reported. Minimal acute in vitro toxicity was observed in multiple cell lines, while longer-term toxicity in cancer cells was observed, with slow-releasing donors exhibiting the greatest cytotoxic effects.

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.

Hydrogen Sulfide Metabolism and Pulmonary Hypertension

Pulmonary hypertension (PH) is a severe and multifactorial disease characterized by a progressive elevation of pulmonary arterial resistance and pressure due to remodeling, inflammation, oxidative stress, and vasoreactive alterations of pulmonary arteries (PAs). Currently, the etiology of these pathological features is not clearly understood and, therefore, no curative treatment is available. Since the 1990s, hydrogen sulfide (H₂S) has been described as the third gasotransmitter with plethoric regulatory functions in cardiovascular tissues, especially in pulmonary circulation. Alteration in H₂S biogenesis has been associated with the hallmarks of PH. H₂S is also involved in pulmonary vascular cell homeostasis via the regulation of hypoxia response and mitochondrial bioenergetics, which are critical phenomena affected during the development of PH. In addition, H₂S modulates ATP-sensitive K⁺ channel (K_ATP) activity, and is associated with PA relaxation. In vitro or in vivo H₂S supplementation exerts antioxidative and anti-inflammatory properties, and reduces PA remodeling. Altogether, current findings suggest that H₂S promotes protective effects against PH, and could be a relevant target for a new therapeutic strategy, using attractive H₂S-releasing molecules. Thus, the present review discusses the involvement and dysregulation of H₂S metabolism in pulmonary circulation pathophysiology.

Implications of Oxidative and Nitrosative Post-Translational Modifications in Therapeutic Strategies against Reperfusion Damage

Post-translational modifications based on redox reactions "switch on-off" the biological activity of different downstream targets, modifying a myriad of processes and providing an efficient mechanism for signaling regulation in physiological and pathological conditions. Such modifications depend on the generation of redox components, such as reactive oxygen species and nitric oxide. Therefore, as the oxidative or nitrosative milieu prevailing in the reperfused heart is determinant for protective signaling, in this review we defined the impact of redox-based post-translational modifications resulting from either oxidative/nitrosative signaling or oxidative/nitrosative stress that occurs during reperfusion damage. The role that cardioprotective conditioning strategies have had to establish that such changes occur at different subcellular levels, particularly in mitochondria, is also presented. Another section is devoted to the possible mechanism of signal delivering of modified proteins. Finally, we discuss the possible efficacy of redox-based therapeutic strategies against reperfusion damage.

New possible silver lining for pancreatic cancer therapy: Hydrogen sulfide and its donors

As one of the most lethal diseases, pancreatic cancer shows a dismal overall prognosis and high resistance to most treatment modalities. Furthermore, pancreatic cancer escapes early detection during the curable period because early symptoms rarely emerge and specific markers for this disease have not been found. Although combinations of new drugs, multimodal therapies, and adjuvants prolong survival, most patients still relapse after surgery and eventually die. Consequently, the search for more effective treatments for pancreatic cancer is highly relevant and justified. As a newly re-discovered mediator of gasotransmission, hydrogen sulfide (H₂S) undertakes essential functions, encompassing various signaling complexes that occupy key processes in human biology. Accumulating evidence indicates that H₂S exhibits bimodal modulation of cancer development. Thus, endogenous or low levels of exogenous H₂S are thought to promote cancer, whereas high doses of exogenous H₂S suppress tumor proliferation. Similarly, inhibition of endogenous H₂S production also suppresses tumor proliferation. Accordingly, H₂S biosynthesis inhibitors and H₂S supplementation (H₂S donors) are two distinct strategies for the treatment of cancer. Unfortunately, modulation of endogenous H₂S on pancreatic cancer has not been studied so far. However, H₂S donors and their derivatives have been extensively studied as potential therapeutic agents for pancreatic cancer therapy by inhibiting cell proliferation, inducing apoptosis, arresting cell cycle, and suppressing invasion and migration through exploiting multiple signaling pathways. As far as we know, there is no review of the effects of H₂S donors on pancreatic cancer. Based on these concerns, the therapeutic effects of some H₂S donors and NO–H₂S dual donors on pancreatic cancer were summarized in this paper. Exogenous H₂S donors may be promising compounds for pancreatic cancer treatment.

N-Methylation of Self-Immolative Thiocarbamates Provides Insights into the Mechanism of Carbonyl Sulfide Release

Hydrogen sulfide (H₂S) is an important biomolecule, and self-immolative thiocarbamates have shown great promise as triggerable H₂S donors with suitable analogous control compounds; however, thiocarbamates with electron-deficient payloads are less efficient H₂S donors. We report here the synthesis and study of a series of N-methylated esterase-triggered thiocarbamates that block the postulated unproductive deprotonation-based pathway for these compounds. The relative reaction profiles for H₂S release across a series of electron-rich and electron-poor N-Me aniline payloads are examined experimentally and computationally. We show that thiocarbamate N-methylation does block some side reactivity and increases the H₂S release profiles for electron-poor donors. Additionally, we show that isothiocyanate release is not a competitive pathway, and rather that the reduced efficiency of electron-poor donors is likely due to other side reactions.

Novel turn-on fluorescence sensor for detection and imaging of endogenous H2S induced by sodium nitroprusside

Currently, fluorescence analysis method has a good application in the detection and imaging of biomarkers and has become an important analytical method. Although there are many fluorescent probes for detecting hydrogen sulfide(H₂S), they are mostly based on fluorophores which already existed, such as 1,8-naphthalimide, coumarin, rhodamine and their derivatives. Here, a new type of fluorescent molecule (BOTD) was synthesized and applied to the detection of H₂S. The probe BOTD could quickly and sensitively detect H₂S and turn on fluorescence. Moreover, the probe BOTD was successfully applied to the detection of exogenous and endogenous H₂S in living cells, and may be expected to become a research tool for studying H₂S-induced drugs.

Neurotransmitter and neuropeptide regulation of mast cell function: a systematic review

The existence of the neural control of mast cell functions has long been proposed. Mast cells (MCs) are localized in association with the peripheral nervous system (PNS) and the brain, where they are closely aligned, anatomically and functionally, with neurons and neuronal processes throughout the body. They express receptors for and are regulated by various neurotransmitters, neuropeptides, and other neuromodulators. Consequently, modulation provided by these neurotransmitters and neuromodulators allows neural control of MC functions and involvement in the pathogenesis of mast cell–related disease states. Recently, the roles of individual neurotransmitters and neuropeptides in regulating mast cell actions have been investigated extensively. This review offers a systematic review of recent advances in our understanding of the contributions of neurotransmitters and neuropeptides to mast cell activation and the pathological implications of this regulation on mast cell–related disease states, though the full extent to which such control influences health and disease is still unclear, and a complete understanding of the mechanisms underlying the control is lacking. Future validation of animal and in vitro models also is needed, which incorporates the integration of microenvironment-specific influences and the complex, multifaceted cross-talk between mast cells and various neural signals. Moreover, new biological agents directed against neurotransmitter receptors on mast cells that can be used for therapeutic intervention need to be more specific, which will reduce their ability to support inflammatory responses and enhance their potential roles in protecting against mast cell–related pathogenesis.

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.

Hydrogen sulfide and cardiovascular disease: Doubts, clues, and interpretation difficulties from studies in geothermal areas

Hydrogen sulfide (H₂S) represents one of the main pollutants originating from both geologic phenomena such as volcanoes, geysers, fumaroles and hot springs, and geothermal plants that produce heat and electricity. Many increasing data suggest that H₂S retains a variety of biological properties, and modulates many pathways related to cardiovascular pathophysiology although its role as beneficial/adverse determinant on cardiovascular disease (CVD) is not clearly established. In this review, the current knowledge on the association between H₂S exposure and risk of CVD in geothermal areas has been examined. The few epidemiological studies carried out in geothermal areas suggest, in some cases, a protective role of H₂S towards CVD, while in others a positive association between exposure to H₂S and increased incidence of CVD. Most of the studies have an ecological design that does not allow to produce evidence to support a causal relationship and also often lack for an adequate adjustment for individual CVD risk factors. The review has also considered the potential role of two other aspects not sufficiently explored in this relationship: the production of endogenous H₂S that is a gasotransmitter producing beneficial effects on cardiovascular function at low concentration and the intake of H₂S-releasing drugs for the treatment of patients affected by hypertension, inflammatory diseases, and CVD. Thus, a threshold effect of H₂S and the shift of action as beneficial/adverse determinant given by the synergy of exogenous exposure and endogenous production cannot be excluded. In this complex scenario, an effort is warranted in the future to include a more comprehensive evaluation of risk for CVD in relation to H₂S emissions, especially in geothermal areas.

H2S Donors Reverse Age-Related Gastric Malfunction Impaired Due to Fructose-Induced Injury via CBS, CSE, and TST Expression

Objective

Excess of fructose consumption is related to life-treating conditions that affected more than a third of the global population. Therefore, to identify a newer therapeutic strategy for the impact prevention of high fructose injury in age-related malfunctions of the gastric mucosa (GM) in the animal model is important.

Methods

Adult and aged male rats were divided into control groups (standard diet, SD) and high fructose diet (HFD) groups; acute water immersion restraint stress (WIRS) was induced for evaluation of GM adaptive response and effects of testing the therapeutic potential of H₂S-releasing compounds (H₂S donors). Histological examination of gastric damage was done on hematoxylin-eosin stained slides. Cystathionine beta-synthase (CBS), Cystathionine gamma-lyase (CSE), and Thiosulfate-dithiol sulfurtransferase (TST) activities and oxidative index were assessed during exogenous administration of H₂S donors: sodium hydrosulfide (NaHS) and the novel hybrid H₂S-releasing aspirin (ATB-340). The results showed that HFD increased gastric damage in adult and aged rats. HFD-associated malfunction characterized by low activities of H₂S key enzymes, inducing increased oxidation. Pretreatment with NaHS, ATB-340 of aged rats in the models of HFD, and WIRS attenuated gastric damage in contrast to vehicle-treated group (p < 0.05). The effect of ATB-340 was characterized by reverse oxidative index and increased CBS, CSE, and TST activities. In conclusion, H₂S donors prevent GM age-related malfunctions by enhancement of CBS, CSE, and TST expression against fructose excess injury though reduction of oxidative damage.

Hydrogen sulfide signaling in regulation of cell behaviors

Recent advances in the biomedical importance of H₂S have help us understand various cellular functions and pathophysiological processes from a new aspect. Specially, H₂S has been demonstrated to play multiple roles in regulating cell behaviors, including cell survival, cell differentiation, cell senescence, cell hypertrophy, cell atrophy, cell metaplasia, and cell death, etc. H₂S contributes to cell behavior changes via various mechanisms, such as histone modification, DNA methylation, non-coding RNA changes, DNA damage repair, transcription factor activity, and post-translational modification of proteins by S-sulfhydration, etc. In this review, we summarized the recent research progress on H₂S signaling in control of cell behaviors and discussed the ways of H₂S regulation of gene expressions. Given the key roles of H₂S in both health and diseases, a better understanding of the regulation of H₂S on cell behavior change and the underlying molecular mechanisms will help us to develop novel and more effective strategies for clinical therapy.

Hydrogen Sulfide Promotes Cardiomyocyte Proliferation and Heart Regeneration via ROS Scavenging

Neonatal mouse hearts can regenerate completely in 21 days after cardiac injury, providing an ideal model to exploring heart regenerative therapeutic targets. The oxidative damage by Reactive Oxygen Species (ROS) is one of the critical reasons for the cell cycle arrest of cardiomyocytes (CMs), which cause mouse hearts losing the capacity to regenerate in 7 days or shorter after birth. As an antioxidant, hydrogen sulfide (H₂S) plays a protective role in a variety of diseases by scavenging ROS produced during the pathological processes. In this study, we found that blocking H₂S synthesis by PAG (H₂S synthase inhibitor) suspended heart regeneration and CM proliferation with ROS deposition increase after cardiac injury (myocardial infarction or apex resection) in 2-day-old mice. NaHS (a H₂S donor) administration improved heart regeneration with CM proliferation and ROS elimination after myocardial infarction in 7-day-old mice. NaHS protected primary neonatal mouse CMs from H₂O₂-induced apoptosis and promoted CM proliferation via SOD2-dependent ROS scavenging. The oxidative DNA damage in CMs was reduced with the elimination of ROS by H₂S. Our results demonstrated for the first time that H₂S promotes heart regeneration and identified NaHS as a potent modulator for cardiac repair.

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

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

Activatable Small-Molecule Hydrogen Sulfide Donors

Significance: Hydrogen sulfide (H2S) is an important biological signaling molecule involved in many physiological processes. These diverse roles have led researchers to develop contemporary methods to deliver H2S under physiologically relevant conditions and in response to various stimuli. Recent Advances: Different small-molecule donors have been developed that release H2S under various conditions. Key examples include donors activated in response to hydrolysis, to endogenous species, such as thiols, reactive oxygen species, and enzymes, and to external stimuli, such as photoactivation and bio-orthogonal chemistry. In addition, an alternative approach to release H2S has utilized the catalyzed hydrolysis of carbonyl sulfide (COS) by carbonic anhydrase to generate libraries of activatable COS-based H2S donors. Critical Issues: Small-molecule H2S donors provide important research and pharmacological tools to perturb H2S levels. Key needs, both in the development and in the use of such donors, include access to new donors that respond to specific stimuli as well as donors with well-defined control compounds that allow for clear delineation of the impact of H2S delivery from other donor byproducts. Future Directions: The abundance of reported small-molecule H2S donors provides biologists and physiologists with a chemical toolbox to ask key biological questions and to develop H2S-related therapeutic interventions. Further investigation into different releasing efficiencies in biological contexts and a clear understanding of biological responses to donors that release H2S gradually (e.g., hours to days) versus donors that generate H2S quickly (e.g., seconds to minutes) is needed.

Hydrogen sulfide signaling in mitochondria and disease

Hydrogen sulfide can signal through 3 distinct mechanisms: 1) reduction and/or direct binding of metalloprotein heme centers, 2) serving as a potent antioxidant through reactive oxygen species/reactive nitrogen species scavenging, or 3) post-translational modification of proteins by addition of a thiol (-SH) group onto reactive cysteine residues: a process known as persulfidation. Below toxic levels, hydrogen sulfide promotes mitochondrial biogenesis and function, thereby conferring protection against cellular stress. For these reasons, increases in hydrogen sulfide and hydrogen sulfide-producing enzymes have been implicated in several human disease states. This review will first summarize our current understanding of hydrogen sulfide production and metabolism, as well as its signaling mechanisms; second, this work will detail the known mechanisms of hydrogen sulfide in the mitochondria and the implications of its mitochondrial-specific impacts in several pathologic conditions.-Murphy, B., Bhattacharya, R., Mukherjee, P. Hydrogen sulfide signaling in mitochondria and disease.

H2S attenuates sepsis-induced cardiac dysfunction via a PI3K/Akt-dependent mechanism

The heart is the most vulnerable target organ in sepsis, and it has been previously reported that hydrogen sulfide (H₂S) has a protective role in heart dysfunction caused by sepsis. Additionally, studies have demonstrated that the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway has a protective function during sepsis. However, the potential association between H₂S and PI3K/Akt in sepsis-induced cardiac dysfunction is unclear. Therefore, the PI3K inhibitor LY294002 was used to investigate the role of PI3K/Akt signaling in the protective effects of H₂S during sepsis-induced myocardial injury. A rat sepsis model was established using cecal ligation and puncture (CLP) surgery. Sodium hydrosulfide, a H₂S donor, was administered intraperitoneally (8.9 µmol/kg), and serum myocardial enzyme levels, inflammatory cytokine levels, cardiac histology and cardiomyocyte apoptosis were assessed to determine the extent of myocardial damage. The results demonstrated that exogenous H₂S reduced serum myocardial enzyme levels, decreased the levels of the inflammatory factors tumor necrosis factor (TNF)-α and interleukin (IL)-6, and increased the level of anti-inflammatory IL-10 following CLP. Staining of histological sections demonstrated that myocardial damage and cardiomyocyte apoptosis were alleviated by the administration of exogenous H₂S. Western blot analysis was used to detect phosphorylated and total PI3K and Akt levels, as well as NF-κB, B-cell lymphoma-2, Bcl-2-associated X protein (Bax) and caspase levels, and the results demonstrated that H₂S significantly increased PI3K and Akt phosphorylation. This indicated that the PI3K/Akt signaling pathway was activated by H₂S. Additionally, H₂S reduced Bax and caspase expression, indicating that apoptosis was inhibited, and decreased NF-κB levels, indicating that inflammation was reduced. Furthermore, the PI3K inhibitor LY294002 eliminated the protective effects of H₂S. In conclusion, the results of the current study suggest that exogenous H₂S activates PI3K/Akt signaling to attenuate myocardial damage in sepsis.