Hydrogen Sulfide (H2S)-Releasing Compounds: Therapeutic Potential in Cardiovascular Diseases

Hydrogen sulfide mitigates ox‑LDL‑induced NLRP3/caspase‑1/GSDMD dependent macrophage pyroptosis by S‑sulfhydrating caspase‑1

Macrophage pyroptosis mediates vascular inflammation and atherosclerosis (AS). Hydrogen sulfide (H2S) exerts a protective role in preventing inflammation and AS. However, its molecular mechanisms of regulating the pyroptosis signaling pathway and inhibiting macrophage pyroptosis remain unexplored. The present study aimed to determine whether H2S mitigates macrophage pyroptosis by downregulating the pyroptosis signaling pathway and S‑sulfhydrating caspase‑1 under the stimulation of oxidized low‑density lipoprotein (ox‑LDL), a pro‑atherosclerotic factor. Macrophages derived from THP‑1 monocytes were pre‑treated using exogenous H2S donors sodium hydrosulfide (NaHS) and D,L‑propargylglycine (PAG), a pharmacological inhibitor of endogenous H2S‑producing enzymes, alone or in combination. Subsequently, cells were stimulated with ox‑LDL or the desulfhydration reagent dithiothreitol (DTT) in the presence or absence of NaHS and/or PAG. Following treatment, the levels of H2S in THP‑1 derived macrophages were measured by a methylene blue colorimetric assay. The pyroptotic phenotype of THP‑1 cells was observed and evaluated by light microscopy, Hoechst 33342/propidium iodide fluorescent staining and lactate dehydrogenase (LDH) release assay. Caspase‑1 activity in THP‑1 cells was assayed by caspase‑1 activity assay kit. Immunofluorescence staining was used to assess the accumulation of active caspase‑1. Western blotting and ELISA were performed to determine the expression of pyroptosis‑specific markers (NLRP3, pro‑caspase‑1, caspase‑1, GSDMD and GSDMD‑N) in cells and the secretion of pyroptosis‑related cytokines [interleukin (IL)‑1β and IL‑18] in the cell‑free media, respectively. The S‑sulfhydration of pro‑caspase‑1 in cells was assessed using a biotin switch assay. ox‑LDL significantly induced macrophage pyroptosis by activating the pyroptosis signaling pathway. Inhibition of endogenous H2S synthesis by PAG augmented the pro‑pyroptotic effects of ox‑LDL. Conversely, exogenous H2S (NaHS) ameliorated ox‑LDL‑and ox‑LDL + PAG‑induced macrophage pyroptosis by suppressing the activation of the pyroptosis signaling pathway. Mechanistically, ox‑LDL and the DTT increased caspase‑1 activity and downstream events (IL‑1β and IL‑18 secretion) of the caspase‑1‑dependent pyroptosis pathway by reducing S‑sulfhydration of pro‑caspase‑1. Conversely, NaHS increased S‑sulfhydration of pro‑caspase‑1, reducing caspase‑1 activity and caspase‑1‑dependent macrophage pyroptosis. The present study demonstrated the molecular mechanism by which H2S ameliorates macrophage pyroptosis by suppressing the pyroptosis signaling pathway and S‑sulfhydration of pro‑caspase‑1, thereby suppressing the generation of active caspase-1 and activity of caspase-1.

Construction of a coumarin-based fluorescent probe for accurately visualizing hydrogen sulfide in live cells and zebrafish

Hydrogen sulfide (H2S), an important gas signaling molecule, is a regulator of many physiological processes, and its abnormal levels are closely related to the onset and progression of disease. It is vital to develop methods for specific tracking of H2S in clinical diagnosis and treatment. In this study, we designed an ultrasensitive and highly stable coumarin-based fluorescent probe Cou-H2S. Through the H2S-initiated tandem reaction, Cou-H2S successfully achieved highly selective and super-fast detection of H2S. Cou-H2S was successfully applied to the monitoring of endogenous and exogenous H2S at the cellular level and verified the validity of the detection of H2S in the LPS-induced zebrafish model. Therefore, Cou-H2S might provide new insights into the study of H2S-related diseases.

Discovery of novel β-elemene hybrids with hydrogen sulfide-releasing moiety possessing cardiovascular protective activity for the treatment of atherosclerosis

Herein, a series of novel β-elemene hybrids with different types of hydrogen sulfide (H2S) donors was designed and synthesized for the first time. In addition, all compounds were tested for H2S release in phosphate buffer solution assay, among which the derivatives with 5-p-hydroxyphenyl-3H-1,2-dithiole-3-thione (ADT-OH) as the H2S donor released the best level. The results of the isolated vasodilation assay revealed that all the compounds exhibited a degree of vasodilatory effect, and the representative compound "β-elemene-H2S gas donor" hybrid L13-2h produced more than 50% vasodilatory activity at a concentration of 20 μM. Furthermore, L13-2h possessed good concentration dependence and significantly better vasodilatory activity than the lead compound L13. In the RAW 264.7 cellular lipid inhibition against oxidized low-density lipoprotein (ox-LDL) stimulation assay, eight compounds, including L13-2g and L13-2h, produced significant cellular lipid-lowering activity. The results of the further antioxidant activity study showed that the representative compounds L13-2g and L13-2h improved H2O2-induced oxidative damage in HUVEC cells and compound L13-2h exhibited excellent antioxidant damage protection activity compared to the positive control. Moreover, none of the target compounds appeared to be significantly cytotoxic at the tested concentrations. These results suggest that the hybridization of hydrogen sulfide donors with β-elemene provides a promising approach for the discovery of novel anti-atherosclerotic drugs from natural products.

Highly Sensitive H2S Gas Sensor Based on a Lead-Free CsCu2I3 Perovskite Film at Room Temperature

Recently, there have been reports of lead halide perovskite-based sensors demonstrating their potential for gas sensing applications. However, the toxicity of lead and the instability of lead-based perovskites have limited their applications. This study addressed this issue by developing a H2S gas sensor based on a lead-free CsCu2I3 film prepared using a one-step CVD method. The sensor demonstrated excellent sensing properties, including a high response and selectivity toward H2S, even at low concentrations (0.2 ppm) at room temperature. Furthermore, a reasonable sensing mechanism was proposed. It is suggested that the sensing mechanism sheds light on the role of defects in perovskite materials, the impact of H2S as an electron donor, and the occurrence of reversible chemical reactions. These findings suggest that lead-free CsCu2I3 has great potential in the field of H2S gas sensing.

Protective Effects of NaHS/miR-133a-3p on Lipopolysaccharide-Induced Cardiomyocytes Injury

Objective

The aim of this study was to investigate the effects of sodium hydrosulfide (NaHS) on Lipopolysaccharide (LPS)-induced cardiomyocyte injury in H9c2 cells.

Methods

H9c2 cardiomyocytes cultivated with medium containing 10 μg/mL LPS were used to recapitulate the phenotypes of those in sepsis. Two sequential experiments were performed. The first contained a control group, a LPS group, and a LPS + NaHS group, with the aim to assure the protective effects of NaHS on LPS-treated cardiomyocytes. The second experiment added a fourth group, the LPS + NaHS + miR-133a-3p inhibition group, with the aim to preliminarily explore whether miR-133-3p exerts a protective function downstream of NaHS. The adenosine triphosphate (ATP) kit was used to detect ATP content; real-time quantitative polynucleotide chain reaction (qPCR) was used to measure the levels of mammalian targets of rapamycin (mTOR), AMP-dependent protein kinase (AMPK), and miR-133a-3p, and Western blot (WB) was used to detect protein levels of mTOR, AMPK, myosin-like Bcl2 interacting protein (Beclin-1), microtubule-associated protein 1 light chain 3 (LC3I/II), and P62 (sequestosome-1, sqstm-1/P62).

Results

Compared with the control group, the expressions of miR-133a-3p (P < 0.001), P62 (P < 0.001), and the content of ATP (P < 0.001) decreased, while the expressions of Beclin-1 (P = 0.023) and LC3I/II (P = 0.048) increased in the LPS group. Compared with the LPS group, the expressions of miR-133a-3p (P < 0.001), P62 (P < 0.001), and the content of ATP (P < 0.001) in the NaHS + LPS group increased, while the expressions of Beclin-1 (P = 0.023) and LC3I/II (P = 0.022) decreased. Compared with the NaHS + LPS group, the expression levels of miR-133a-3p (P < 0.001), P62 (P = 0.001), and the content of ATP (P < 0.001) in the LPS + NaHS + miR-133a-3p inhibition group were downregulated, and the expression levels of Beclin-1 (P = 0.012) and LC3I/II (P = 0.010) were upregulated. The difference was statistically significant. There was no significant difference in the expression of AMPK and mTOR between groups.

Conclusion

Our research demonstrated that NaHS relieved LPS-induced myocardial injury in H9c2 by promoting the expression of miR-133a-3p, inhibiting autophagy in cardiomyocytes, and restoring cellular ATP levels.

Targeting the redox system for cardiovascular regeneration in aging

Cardiovascular aging presents a formidable challenge, as the aging process can lead to reduced cardiac function and heightened susceptibility to cardiovascular diseases. Consequently, there is an escalating, unmet medical need for innovative and effective cardiovascular regeneration strategies aimed at restoring and rejuvenating aging cardiovascular tissues. Altered redox homeostasis and the accumulation of oxidative damage play a pivotal role in detrimental changes to stem cell function and cellular senescence, hampering regenerative capacity in aged cardiovascular system. A mounting body of evidence underscores the significance of targeting redox machinery to restore stem cell self-renewal and enhance their differentiation potential into youthful cardiovascular lineages. Hence, the redox machinery holds promise as a target for optimizing cardiovascular regenerative therapies. In this context, we delve into the current understanding of redox homeostasis in regulating stem cell function and reprogramming processes that impact the regenerative potential of the cardiovascular system. Furthermore, we offer insights into the recent translational and clinical implications of redox-targeting compounds aimed at enhancing current regenerative therapies for aging cardiovascular tissues.

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.

Hydrogen sulfide inhibits gene expression associated with aortic valve degeneration by inducing NRF2-related pro-autophagy effect in human aortic valve interstitial cells

Aortic valve stenosis (AS) is the most common valvular heart disease but there are currently no effective medical treatments that can delay disease progression due to a lack of knowledge of the precise pathophysiology. The expression of sulfide: quinone oxidoreductase (SQOR) and nuclear factor erythroid 2-related factor 2 (NRF2) was decreased in the aortic valve of AS patients. However, the role of SQOR and NRF2 in the pathophysiology of AS has not been found. We investigated the effects of hydrogen sulfide (H2S)-releasing compounds on diseased aortic valve interstitial cells (AVICs) to explain the cellular mechanism of SQOR and elucidate the medical value of H2S for AS treatment. Sodium hydrosulfide (NaHS) treatment increased the expression of SQOR and NRF2 gene and consequently induced the NRF2 target genes, such as NAD(P)H quinone dehydrogenase 1 and cystathionine γ-lyase. In addition, NaHS dose-dependently decreased the expression level of fibrosis and inflammation-related genes (MMP9, TNF-α, IL6) and calcification-related genes (ALP, osteocalcin, RUNX2, COL1A1) in human AVICs. Furthermore, NaHS activated the AMPK-mTOR pathway and inhibited the PI3K-AKT pathway, resulting in a pro-autophagy effect in human AVICs. An NRF2 inhibitor, brusatol, attenuated NaHS-induced AMPK activation and decreased the autophagy markers Beclin-1 and LC3AB, suggesting that the mechanism of action of H2S is related to NRF2. In conclusion, H2S decreased gene expression levels related to aortic valve degeneration and activated AMPK-mTOR-mediated pro-autophagy function associated with NRF2 in human AVICs. Therefore, H2S could be a potential therapeutic target for the development of AS treatment.

Construction of a novel chitosan-based macromolecular nanoprobe for specific fluorescent detection of H2S in live animals

H2S is one of the signal molecules in live organisms and a poisonous gas, which is closely related to our life. The traditional synthetic small molecular organic probes often have the disadvantages of low biocompatibility. In this paper, a fluorescent nanoprobe for detecting H2S in live organisms was constructed based on chitosan. The structure of CH-CN was characterized by infrared spectroscopy, nuclear magnetic resonance, x-ray photoelectron spectroscopy (XPS), XRD and scanning electron microscope (SEM). In the presence of Na2S, the fluorescence intensity at 560 nm was significantly enhanced, and showed high selectivity and sensitivity toward H2S. Based on the good fluorescence response of CH-CN, the probe was also successfully applied to H2S imaging in HepG2 cells and zebrafish. These experimental results indicate that the probe has lower cytotoxicity and excellent stability. The present research shows a typical example of construction of chitosan-based macromolecular fluorescent materials and their bio-imaging application.

Cystathionine Gamma Lyase Is Regulated by Flow and Controls Smooth Muscle Migration in Human Saphenous Vein

The saphenous vein is the conduit of choice for bypass grafting. Unfortunately, the hemodynamic stress associated with the arterial environment of the bypass vein graft leads to the development of intimal hyperplasia (IH), an excessive cellular growth and collagen deposition that results in restenosis and secondary graft occlusion. Hydrogen sulfide (H2S) is a ubiquitous redox-modifying gasotransmitter that inhibits IH. H2S is produced via the reverse trans-sulfuration pathway by three enzymes: cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). However, the expression and regulation of these enzymes in the human vasculature remains unclear. Here, we investigated the expression of CSE, CBS and 3-MST in segments of native human saphenous vein and large arteries. Furthermore, we evaluated the regulation of these enzymes in vein segments cultured under static, venous (7 mmHg pressure) or arterial (100 mmHg pressure) pressure. CSE was expressed in the media, neointima and intima of the vessels and was negatively regulated by arterial shear stress. Adenoviral-mediated CSE overexpression or RNA interference-mediated CSE knock-down revealed that CSE inhibited primary human VSMC migration but not proliferation. We propose that high shear stress in arteriovenous bypass grafts inhibits CSE expression in both the media and endothelium, which may contribute to increased VSMC migration in the context of IH.

Near-Infrared Fluorescent Probe for Imaging Upregulated Hydrogen Sulfide Levels in Rice under Salt and Drought Stress

Hydrogen sulfide (H₂S) is a hazardous gas found in living organisms and is directly tied to our daily lives. Recent studies show that it plays a significant role in plant growth, development, and response to environmental stresses. However, few of the reported near-infrared (NIR) fluorescent probes have been applied to rice and deeply investigated the influence of the external environment on the biological molecules in its internal environment. Therefore, our team created BSZ-H₂S, which has the advantage of an emission wavelength of up to 720 nm with fast response, successfully applying it to cell and zebrafish imaging. More importantly, the probe detected H₂S in rice roots by in situ imaging in a facile manner and verified the existence of an upregulation process of H₂S in response to salt and drought stress. This work provides a concept for the intervention of external stresses in rice culture.

H2S Prodrug, SG-1002, Protects against Myocardial Oxidative Damage and Hypertrophy In Vitro via Induction of Cystathionine β-Synthase and Antioxidant Proteins

Endogenously produced hydrogen sulfide (H₂S) is critical for cardiovascular homeostasis. Therapeutic strategies aimed at increasing H₂S levels have proven cardioprotective in models of acute myocardial infarction (MI) and heart failure (HF). The present study was undertaken to investigate the effects of a novel H₂S prodrug, SG-1002, on stress induced hypertrophic signaling in murine HL-1 cardiac muscle cells. Treatment of HL-1 cells with SG-1002 under serum starvation without or with H₂O₂ increased the levels of H₂S, H₂S producing enzyme, and cystathionine β-synthase (CBS), as well as antioxidant protein levels, such as super oxide dismutase1 (SOD1) and catalase, and additionally decreased oxidative stress. SG-1002 also decreased the expression of hypertrophic/HF protein markers such as atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), galectin-3, TIMP1, collagen type III, and TGF-β1 in stressed HL-1 cells. Treatment with SG-1002 caused a significant induction of cell viability and a marked reduction of cellular cytotoxicity in HL-1 cells under serum starvation incubated without or with H₂O₂. Experimental results of this study suggest that SG-1002 attenuates myocardial cellular oxidative damage and/or hypertrophic signaling via increasing H₂S levels or H₂S producing enzymes, CBS, and antioxidant proteins.

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.

Comparative Study of Different H2S Donors as Vasodilators and Attenuators of Superoxide-Induced Endothelial Damage

In the last years, research proofs have confirmed that hydrogen sulfide (H₂S) plays an important role in various physio-pathological processes, such as oxidation, inflammation, neurophysiology, and cardiovascular protection; in particular, the protective effects of H₂S in cardiovascular diseases were demonstrated. The interest in H₂S-donating molecules as tools for biological and pharmacological studies has grown, together with the understanding of H₂S importance. Here we performed a comparative study of a series of H₂S donor molecules with different chemical scaffolds and H₂S release mechanisms. The compounds were tested in human serum for their stability and ability to generate H₂S. Their vasorelaxant properties were studied on rat aorta strips, and the capacity of the selected compounds to protect NO-dependent endothelium reactivity in an acute oxidative stress model was tested. H₂S donors showed different H₂S-releasing kinetic and produced amounts and vasodilating profiles; in particular, compound 6 was able to attenuate the dysfunction of relaxation induced by pyrogallol exposure, showing endothelial protective effects. These results may represent a useful basis for the rational development of promising H₂S-releasing agents also conjugated with other pharmacophores.

Development of Hydrogen Sulfide-Releasing Carbonic Anhydrases IX- and XII-Selective Inhibitors with Enhanced Antihyperalgesic Action in a Rat Model of Arthritis

An effective therapeutic approach based on the anti-inflammatory action of hydrogen sulfide (H₂S) and inhibition of carbonic anhydrases (CAs) IX and XII is proposed here for the management of arthritis. H₂S is a human gasotransmitter that modulates inflammatory response at low concentrations. Inhibition of CAs IX and XII can repristinate normal pH in the acidic inflamed synovial fluid, alleviating arthritis symptoms. We report here the design of H₂S donor—CA inhibitor (CAI) hybrid derivatives. The latter were tested in vitro as inhibitors of human CAs I, II, IV, IX, and XII, showing a markedly increased inhibition potency/isoform selectivity compared to the CAI synthetic precursors. The best compounds demonstrated the ability to consistently release H₂S and produce a potent pain-relieving effect in a rat model of arthritis. Compound 26 completely reverted the pain state 45 min after administration with enhanced antihyperalgesic effect in vivo compared to the single H₂S donor, CAI fragment, or their co-administration.

Nitric Oxide-Releasing Platforms for Treating Cardiovascular Disease

Cardiovascular disease (CVD) is the first leading cause of death globally. Nitric oxide (NO) is an important signaling molecule that mediates diverse processes in the cardiovascular system, thereby providing a fundamental basis for NO-based therapy of CVD. At present, numerous prodrugs have been developed to release NO in vivo. However, the clinical application of these prodrugs still faces many problems, including the low payloads, burst release, and non-controlled delivery. To address these, various biomaterial-based platforms have been developed as the carriers to deliver NO to the targeted tissues in a controlled and sustained manner. This review aims to summarize recent developments of various therapeutic platforms, engineered to release NO for the treatment of CVD. In addition, two potential strategies to improve the effectiveness of existing NO therapy are also discussed, including the combination of NO-releasing platforms and either hydrogen sulfide-based therapy or stem cell therapy. Hopefully, some NO-releasing platforms may provide important therapeutic benefits for CVD.

Recent Advances in Molecular Research on Hydrogen Sulfide (H2S) Role in Diabetes Mellitus (DM)-A Systematic Review

Abundant experimental data suggest that hydrogen sulfide (H₂S) is related to the pathophysiology of Diabetes Mellitus (DM). Multiple molecular mechanisms, including receptors, membrane ion channels, signalingmolecules, enzymes, and transcription factors, are known to be responsible for the H₂S biological actions; however, H₂S is not fully documented as a gaseous signaling molecule interfering with DM and vascular-linked pathology. In recent decades, multiple approaches regarding therapeutic exploitation of H₂S have been identified, either based on H₂S exogenous apport or on its modulated endogenous biosynthesis. This paper aims to synthesize and systematize, as comprehensively as possible, the recent literature-related data regarding the therapeutic/rehabilitative role of H₂S in DM. This review was conducted following the “Preferred reporting items for systematic reviews and meta-analyses” (PRISMA) methodology, interrogating five international medically renowned databases by specific keyword combinations/“syntaxes” used contextually, over the last five years (2017–2021). The respective search/filtered and selection methodology we applied has identified, in the first step, 212 articles. After deploying the next specific quest steps, 51 unique published papers qualified for minute analysis resulted. To these bibliographic resources obtained through the PRISMA methodology, in order to have the best available information coverage, we added 86 papers that were freely found by a direct internet search. Finally, we selected for a connected meta-analysis eight relevant reports that included 1237 human subjects elicited from clinical trial registration platforms. Numerous H₂S releasing/stimulating compounds have been produced, some being used in experimental models. However, very few of them were further advanced in clinical studies, indicating that the development of H₂S as a therapeutic agent is still at the beginning.

Hypothermia-Triggered Mesoporous Silica Particles for Controlled Release of Hydrogen Sulfide to Reduce the I/R Injury of the Myocardium

Despite the fact that heart transplantation (HTx) is a relatively mature procedure, heart ischemic and reperfusion (I/R) injury during HTx remains a challenge. Even after a successful operation, the heart will be at risk of primary graft failure and mortality during the first year. In this study, temperature-sensitive polymer poly(N-n-propylacrylamide-co-N-tert-butyl acrylamide) (PNNTBA) was coated on diallyl trisulfide (DATS)-loaded mesoporous silica nanoparticles (DATS-MSN) to synthesize hypothermia-triggered hydrogen sulfide (H₂S) releasing particles (HT-MSN). Because the PNNTBA shell dissolves in phosphate-buffered saline at 4 °C, the loaded DATS could continuously release H₂S within 6 h when activated by glutathione (GSH). Furthermore, after co-culturing biocompatible HT-MSN with cardiomyocytes, H₂S released from HT-MSN at 4 °C was found to protect cardiomyocytes from ischemic and reperfusion (I/R) injury. In detail, the rate of cell apoptosis and lactate dehydrogenase activity was decreased, as manifested by increased BCL-2 expression and decreased BAX expression. More importantly, in an isolated heart preservation experiment, HT-MSN demonstrated potent protection against cardiac I/R injury and reduced expression of inflammatory factors TNF-α and IL-1β. This study provided a new method for the controlled release of H₂S by the donor and myocardial protection from I/R injury.

Implications of Hydrogen Sulfide in Development of Pulmonary Hypertension

The pathological mechanisms underlying pulmonary hypertension (PH), as well as its treatment strategy, are crucial issues in this field. This review aimed to summarize the pathological mechanisms by which the hydrogen sulfide (H2S) pathway contributes to PH development and its future implications. The data in this review were obtained from Medline and PubMed sources up to 2022 using the search terms "hydrogen sulfide" and "pulmonary hypertension". In the review, we discussed the significance of endogenous H2S pathway alteration in PH development and showed the advance of the role of H2S as the third gasotransmitter in the mechanisms for hypoxic PH, monocrotaline-induced PH, high blood flow-induced PH, and congenital heart disease-associated PH. Notably, H2S plays a crucial role in the development of PH via certain mechanisms, such as inhibiting the proliferation of pulmonary artery smooth muscle cells, suppressing the inflammation and oxidative stress of pulmonary artery endothelial cells, inducing pulmonary artery smooth muscle cell apoptosis, and interacting with other gaseous signaling pathways. Recently, a variety of H2S donors were developed, including naturally occurring donors and synthetic H2S donors. Therefore, understanding the role of H2S in PH development may help in further exploring novel potential therapeutic targets of PH.

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.

From Tumor Cells to Endothelium and Gut Microbiome: A Complex Interaction Favoring the Metastasis Cascade

Metastasis is a complicated process through which tumor cells disseminate to distant organs and adapt to novel tumor microenvironments. This multi-step cascade relies on the accumulation of genetic and epigenetic alterations within the tumor cells as well as the surrounding non-tumor stromal cells. Endothelial cells constitute a major player in promoting metastasis formation either by inducing the growth of tumor cells or by directing them towards dissemination in the blood or lymph. In fact, the direct and indirect interactions between tumor and endothelial cells were shown to activate several mechanisms allowing cancer cells’ invasion and extravasation. On the other side, gastrointestinal cancer development was shown to be associated with the disruption of the gut microbiome. While several proposed mechanisms have been investigated in this regard, gut and tumor-associated microbiota were shown to impact the gut endothelial barrier, increasing the dissemination of bacteria through the systemic circulation. This bacterial dislocation allows the formation of an inflammatory premetastatic niche in the distant organs promoting the metastatic cascade of primary tumors. In this review, we discuss the role of the endothelial cells in the metastatic cascade of tumors. We will focus on the role of the gut vascular barrier in the regulation metastasis. We will also discuss the interaction between this vascular barrier and the gut microbiota enhancing the process of metastasis. In addition, we will try to elucidate the different mechanisms through which this bacterial dislocation prepares the favorable metastatic niche at distant organs allowing the dissemination and successful deposition of tumor cells in the new microenvironments. Finally, and given the promising results of the studies combining immune checkpoint inhibitors with either microbiota alterations or anti-angiogenic therapy in many types of cancer, we will elaborate in this review the complex interaction between these 3 factors and their possible therapeutic combination to optimize response to treatment.

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

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

Clinical Use of Hydrogen Sulfide to Protect Against Intimal Hyperplasia

Arterial occlusive disease is the narrowing of the arteries via atherosclerotic plaque buildup. The major risk factors for arterial occlusive disease are age, high levels of cholesterol and triglycerides, diabetes, high blood pressure, and smoking. Arterial occlusive disease is the leading cause of death in Western countries. Patients who suffer from arterial occlusive disease develop peripheral arterial disease (PAD) when the narrowing affects limbs, stroke when the narrowing affects carotid arteries, and heart disease when the narrowing affects coronary arteries. When lifestyle interventions (exercise, diet…) fail, the only solution remains surgical endovascular and open revascularization. Unfortunately, these surgeries still suffer from high failure rates due to re-occlusive vascular wall adaptations, which is largely due to intimal hyperplasia (IH). IH develops in response to vessel injury, leading to inflammation, vascular smooth muscle cells dedifferentiation, migration, proliferation and secretion of extra-cellular matrix into the vessel’s innermost layer or intima. Re-occlusive IH lesions result in costly and complex recurrent end-organ ischemia, and often lead to loss of limb, brain function, or life. Despite decades of IH research, limited therapies are currently available. Hydrogen sulfide (H₂S) is an endogenous gasotransmitter derived from cysteine metabolism. Although environmental exposure to exogenous high H₂S is toxic, endogenous H₂S has important vasorelaxant, cytoprotective and anti-inflammatory properties. Its vasculo-protective properties have attracted a remarkable amount of attention, especially its ability to inhibit IH. This review summarizes IH pathophysiology and treatment, and provides an overview of the potential clinical role of H₂S to prevent IH and restenosis.

Sodium thiosulfate acts as a hydrogen sulfide mimetic to prevent intimal hyperplasia via inhibition of tubulin polymerisation

Background

Intimal hyperplasia (IH) remains a major limitation in the long-term success of any type of revascularisation. IH is due to vascular smooth muscle cell (VSMC) dedifferentiation, proliferation and migration. The gasotransmitter Hydrogen Sulfide (H₂S), mainly produced in blood vessels by the enzyme cystathionine- γ-lyase (CSE), inhibits IH in pre-clinical models. However, there is currently no H₂S donor available to treat patients. Here we used sodium thiosulfate (STS), a clinically-approved source of sulfur, to limit IH.

Methods

Low density lipoprotein receptor deleted (LDLR^−/−), WT or Cse-deleted (Cse^−/−) male mice randomly treated with 4 g/L STS in the water bottle were submitted to focal carotid artery stenosis to induce IH. Human vein segments were maintained in culture for 7 days to induce IH. Further in vitro studies were conducted in primary human vascular smooth muscle cells (VSMCs).

Findings

STS inhibited IH in WT mice, as well as in LDLR^−/− and Cse^−/− mice, and in human vein segments. STS inhibited cell proliferation in the carotid artery wall and in human vein segments. STS increased polysulfides in vivo and protein persulfidation in vitro, which correlated with microtubule depolymerisation, cell cycle arrest and reduced VSMC migration and proliferation.

Interpretation

STS, a drug used for the treatment of cyanide poisoning and calciphylaxis, protects against IH in a mouse model of arterial restenosis and in human vein segments. STS acts as an H₂S donor to limit VSMC migration and proliferation via microtubule depolymerisation.

Funding

This work was supported by the Swiss National Science Foundation (grant FN-310030_176158 to FA and SD and PZ00P3-185927 to AL); the Novartis Foundation to FA; and the Union des Sociétés Suisses des Maladies Vasculaires to SD, and the Fondation pour la recherche en chirurgie vasculaire et thoracique.

Hydrogen Sulphide Release via the Angiotensin Converting Enzyme Inhibitor Zofenopril Prevents Intimal Hyperplasia in Human Vein Segments and in a Mouse Model of Carotid Artery Stenosis

OBJECTIVE

Hypertension is a major risk factor for intimal hyperplasia (IH) and re-stenosis following vascular and endovascular interventions. Preclinical studies suggest that hydrogen sulphide (H₂S), an endogenous gasotransmitter, limits re-stenosis. While there is no clinically available pure H₂S releasing compound, the sulfhydryl containing angiotensin converting enzyme inhibitor zofenopril is a source of H₂S. Here, it was hypothesised that zofenopril, due to H₂S release, would be superior to other non-sulfhydryl containing angiotensin converting enzyme inhibitors (ACEi) in reducing intimal hyperplasia.

METHODS

Spontaneously hypertensive male Cx40 deleted mice (Cx40^-/-) or wild type (WT) littermates were randomly treated with enalapril 20 mg or zofenopril 30 mg. Discarded human vein segments and primary human smooth muscle cells (SMCs) were treated with the active compound enalaprilat or zofenoprilat. IH was evaluated in mice 28 days after focal carotid artery stenosis surgery and in human vein segments cultured for seven days ex vivo. Human primary smooth muscle cell (SMC) proliferation and migration were studied in vitro.

RESULTS

Compared with control animals (intima/media thickness 2.3 ± 0.33 μm), enalapril reduced IH in Cx40^-/- hypertensive mice by 30% (1.7 ± 0.35 μm; p = .037), while zofenopril abrogated IH (0.4 ± 0.16 μm; p < .002 vs. control and p > .99 vs. sham operated Cx40^-/- mice). In WT normotensive mice, enalapril had no effect (0.9665 ± 0.2 μm in control vs. 1.140 ± 0.27 μm; p > .99), while zofenopril also abrogated IH (0.1623 ± 0.07 μm; p < .008 vs. control and p > .99 vs. sham operated WT mice). Zofenoprilat, but not enalaprilat, also prevented IH in human vein segments ex vivo. The effect of zofenopril on carotid and SMCs correlated with reduced SMC proliferation and migration. Zofenoprilat inhibited the mitogen activated protein kinase and mammalian target of rapamycin pathways in SMCs and human vein segments.

CONCLUSION

Zofenopril provides extra beneficial effects compared with non-sulfhydryl ACEi in reducing SMC proliferation and re-stenosis, even in normotensive animals. These findings may hold broad clinical implications for patients suffering from vascular occlusive diseases and hypertension.

The hepatic compensatory response to elevated systemic sulfide promotes diabetes

Impaired hepatic glucose and lipid metabolism are hallmarks of type 2 diabetes. Increased sulfide production or sulfide donor compounds may beneficially regulate hepatic metabolism. Disposal of sulfide through the sulfide oxidation pathway (SOP) is critical for maintaining sulfide within a safe physiological range. We show that mice lacking the liver- enriched mitochondrial SOP enzyme thiosulfate sulfurtransferase (Tst-/- mice) exhibit high circulating sulfide, increased gluconeogenesis, hypertriglyceridemia, and fatty liver. Unexpectedly, hepatic sulfide levels are normal in Tst-/- mice because of exaggerated induction of sulfide disposal, with associated suppression of global protein persulfidation and nuclear respiratory factor 2 target protein levels. Hepatic proteomic and persulfidomic profiles converge on gluconeogenesis and lipid metabolism, revealing a selective deficit in medium-chain fatty acid oxidation in Tst-/- mice. We reveal a critical role of TST in hepatic metabolism that has implications for sulfide donor strategies in the context of metabolic disease.

Inverse association of plasma hydrogen sulfide levels with visceral fat area among Chinese young men: a cross-sectional study

Objective

To investigate the association between plasma Hydrogen Sulfide (H₂S) levels and visceral fat area (VFA) among Chinese young men.

Methods

This cross-sectional study involved 156 Chinese male subjects, aged 18-45 years, who visited the First Hospital of Qinhuangdao (Hebei, China) in 2014 for annual health check-up. Participants were categorized into: low (VFA < 75.57 cm²), medium (75.57 cm² ≤ VFA<100.37 cm²), and high (VFA ≥ 100.37 cm²) (n = 52/group). We estimated VFA and plasma H₂S levels by using bioelectrical impedance analysis and a fluorescence probe-based approach, respectively. The associations of H₂S with VFA and obesity anthropometric measures were assessed.

Results

In the high VFA group, the body mass index (BMI, 30.4 ± 2.45 kg/m²), total body fat (TBF, 27.9 ± 3.23 kg), plasma H₂S (3.5 µmol/L), free fatty acid (FFA, 0.6 ± 0.24 mmol/L), triglyceride (TG, 2.0 mmol/L), and total cholesterol (TC, 5.5 ± 1.02 mmol/L) levels were significantly higher than that of those of the low and medium VFA groups, respectively (P < 0.05). Plasma H₂S levels were found to be inversely correlated with VFA, TBF, waist circumference, BMI, FFA, LnFINS, LnHOMA-IR, LnTG, TC, and LDL-C (P < 0.05). Multiple backward stepwise regression analysis revealed an inverse correlation of plasma H₂S levels with FFA (β = -0.214, P = 0.005) and VFA (β = -0.429, P < 0.001), independent of adiposity measures and other confounding factors.

Conclusion

VFA was independently and inversely associated with plasma H₂S levels among Chinese young men. Therefore, determining plasma H₂S levels could aid in the assessment of abnormal VAT distribution.

Hydrogen sulfide plays a potential alternative for the treatment of metabolic disorders of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a cardiovascular complication that tends to occur in patients with diabetes, obesity, or insulin resistance, with a higher late mortality rate. Sustained hyperglycemia, increased free fatty acids, or insulin resistance induces metabolic disorders in cardiac tissues and cells, leading to myocardial fibrosis, left ventricular hypertrophy, diastolic and/or systolic dysfunction, and finally develop into congestive heart failure. The close connection between all signaling pathways and the complex pathogenesis of DCM cause difficulties in finding effective targets for the treatment of DCM. It reported that hydrogen sulfide (H₂S) could regulate cell energy substrate metabolism, reduce insulin resistance, protect cardiomyocytes, and improve myocardial function by acting on related key proteins such as differentiation cluster 36 (CD36) and glucose transporter 4 (GLUT4). In this article, the relative mechanisms of H₂S in alleviating metabolic disorders of DCM were reviewed, and how H₂S can better prevent and treat DCM in clinical practice will be discussed.

H2S alleviates aortic aneurysm and dissection: Crosstalk between transforming growth factor 1 signaling and NLRP3 inflammasome

BACKGROUND

Vascular remodeling and inflammation are involved in aortic aneurysm (AA) and aortic dissection (AD). TGF-β1 signaling is involved in tissue fibrosis, extracellular matrix remodeling and inflammation, which are linked with AA and AD. The inhibition of NLRP3 inflammasome suppresses AA and AD. Hydrogen sulfide (H₂S) exerts anti-vascular remodeling and anti-inflammatory properties, but little is known about its action on AA and AD progression.

METHODS

The effect of H₂S on AA and AD formation was investigated in Sprague-Dawley (SD) rat fed a normal diet supplemented with 0.25% β-aminopropionitrile (BAPN). HE staining, Masson's trichrome staining, Picrosirius red staining and EVG staining were to evaluate vascular remodeling in the aortic wall. Western blotting and IHC were to detect the expression of TGF-β1 and matrix metalloproteinases (MMPs) and NLRP3 inflammasome-associated proteins. The interaction between TGF-β1 signaling and NLRP3 inflammasome was explored in Human aortic vascular smooth muscle cells (HA-VSMCs).

RESULTS

H₂S alleviated AA and AD progression. Specifically, it improved irregular tissue arrangement and vascular fibrosis, increased the expression of elastin fibers, decreased collagen deposition and the expression of TGF-β1 and matrix metalloproteinases (MMP-2/9). In addition, H₂S inhibited the expression of proteins involved in NLRP3 inflammasome. Furthermore, H₂S down-regulated TGF-β1 signaling and then ameliorated vascular fibrosis by preventing NLRP3 inflammasome activation. Finally, H₂S inhibited NLRP3 inflammasome activation and decreased the level of IL-1β by disrupting TGF-β1 signaling.

CONCLUSIONS

These data support a crosstalk between TGF-β1 signaling and NLRP3 inflammasome. H₂S inhibits AA and AD progression via blocking the crosstalk.

Hydrogen Sulphide and Nitric Oxide Cooperate in Cardioprotection Against Ischemia/Reperfusion Injury in Isolated Rat Heart

BACKGROUND/AIM

This study was designed to provide further evidence for the interactions between hydrogen sulfide (H₂S) and nitric oxide (NO) in ischemia/reperfusion (I/R) injury.

MATERIALS AND METHODS

Rat hearts were studied with the Langendorff technique using the H₂S donor sodium hydrosulfide (NaHS, 40 μM) and the cystathionine gamma-lyase (CTH or CSE) inhibitor DL-propargylglycine (PAG, 1 mM). NO synthase inhibitor L-NG-nitroarginine methyl ester (L-NAME, 30 mg/kg, 7 days) was administered before the isolation. The hearts were homogenized for biochemical and molecular analysis.

RESULTS

NaHS reversed I/R-induced cardiac performance impairment, increased tissue nitric oxide production and decreased tissue markers for cardiac injury, while L-NAME inhibited these effects. The expression of CTH was increased with PAG, which was suppressed by L-NAME.

CONCLUSION

H₂S and NO increase each other's production suggesting their interaction and cooperation in cardioprotection against I/R injury.

Alkylsulfenyl thiocarbonates: precursors to hydropersulfides potently attenuate oxidative stress

The recent discovery of the prevalence of hydropersulfides (RSSH) species in biological systems suggests their potential roles in cell regulatory processes. However, the reactive and transient nature of RSSH makes their study difficult, and dependent on the use of donor molecules. Herein, we report alkylsulfenyl thiocarbonates as a new class of RSSH precursors that efficiently release RSSH under physiologically relevant conditions. RSSH release kinetics from these precursors are tunable through electronic modification of the thiocarbonate carbonyl group's electrophilicity. In addition, these precursors also react with thiols to release RSSH with a minor amount of carbonyl sulfide (COS). Importantly, RSSH generation by these precursors protects against oxidative stress in H9c2 cardiac myoblasts. Furthermore, we demonstrate the ability of these precursors to increase intracellular RSSH levels.

Hybrids between H2S-donors and betamethasone 17-valerate or triamcinolone acetonide inhibit mast cell degranulation and promote hyperpolarization of bronchial smooth muscle cells

Glucocorticoids represent the standard gold treatment of inflammation in asthmatic patients. More recently, H₂S has been described to exert positive effect on this disease. Bearing in mind that an improved pharmacological activity and a reduced toxicity can be obtained through hybridization of different molecules, simultaneously modulating multiple targets, we designed and synthesized novel betamethasone 17-valerate and triamcinolone acetonide hybrids with well-known H₂S-donor moieties. Synthesized compounds have been evaluated for the potential H₂S-releasing profile both in cell-free environment and into the cytosol of bronchial smooth muscle cells (BSMCs). The two hybrids 4b and 5b were investigated by molecular modelling studies and results indicated that the steric accessibility of the isothiocyanate carbon atom can account for their different H₂S releasing properties. Furthermore, the most promising derivatives 4b and 5b have been tested for inhibitory effect on mast cell degranulation and for the ability to induce cell membrane hyperpolarization in BSMCs. Significant inhibitory effect on mast cell degranulation was assessed, resulting to reduce β-hexosaminidase release more efficiently than the corresponding native drugs. Both compounds determined a massive membrane hyperpolarization of BSMCs and proved to be 4-fold more effective compared to reference compound NS1619. These effects represent an enrichment of the pharmacological activity of the native drugs.

Mechanisms of thrombosis and research progress on targeted antithrombotic drugs

Globally, the incidence of thromboembolic diseases has increased in recent years, accompanied by an increase in patient mortality. Currently, several targeting delivery strategies have been developed to treat thromboembolic diseases. In this review, we discuss the mechanisms of thrombolysis and current anticoagulant drugs, particularly those with targeting capability, highlighting advances in the accurate treatment of thrombolysis with fewer adverse effects. Such approaches include magnetic drug-loading systems combined with molecular imaging to recanalize blood vessels and systems based on chimeric Arg-Gly-Asp (RGD) sequences that can target platelet glycoprotein receptor. With such progress in targeted antithrombotic drugs, targeted thrombolysis treatment shows significant potential benefit for patients.

H2S Pretreatment Is Promigratory and Decreases Ischemia/Reperfusion Injury in Human Microvascular Endothelial Cells

Endothelial cell injury and vascular function strongly correlate with cardiac function following ischemia/reperfusion injury. Several studies indicate that endothelial cells are more sensitive to ischemia/reperfusion compared to cardiomyocytes and are critical mediators of cardiac ischemia/reperfusion injury. H₂S is involved in the regulation of cardiovascular system homeostasis and can act as a cytoprotectant during ischemia/reperfusion. Activation of ERK1/2 in endothelial cells after H₂S stimulation exerts an enhancement of angiogenesis while its inhibition significantly decreases H₂S cardioprotective effects. In this work, we investigated how H₂S pretreatment for 24 hours prevents the ischemia/reperfusion injury and promotes angiogenesis on microvascular endothelial cells following an ischemia/reperfusion protocol in vitro, using a hypoxic chamber and ischemic buffer to simulate the ischemic event. H₂S preconditioning positively affected cell viability and significantly increased endothelial cell migration when treated with 1 μM H₂S. Furthermore, mitochondrial function was preserved when cells were preconditioned. Since ERK1/2 phosphorylation was extremely enhanced in ischemia/reperfusion condition, we inhibited ERK both directly and indirectly to verify how H₂S triggers this pathway in endothelial cells. Taken together, our data suggest that H₂S treatment 24 hours before the ischemic insult protects endothelial cells from ischemia/reperfusion injury and eventually decreases myocardial injury.

Recent advances in the protective role of hydrogen sulfide in myocardial ischemia/reperfusion injury: a narrative review

Hydrogen sulfide (H₂S) is recognized to be a novel mediator after carbon monoxide and nitric oxide in the organism. It can be produced in various mammalian tissues and exert many physiological effects in many systems including the cardiovascular system. A great amount of recent studies have demonstrated that endogenous H₂S and exogenous H₂S-releasing compounds (such as NaHS, Na₂S, and GYY4137) provide protection in many cardiovascular diseases, such as ischemia/reperfusion injury, heart failure, cardiac hypertrophy, and atherosclerosis. In recent years, many mechanisms have been proposed and verified the protective role exhibited by H₂S against myocardial ischemia/reperfusion injury, and this review is to demonstrate the protective role of exogenous and endogenous H₂S on myocardial ischemia/reperfusion injury.

Involvement of amylin B-H2S-connexin 43 signaling pathway in vascular dysfunction and enhanced ischemia-reperfusion-induced myocardial injury in diabetic rats

The present study was designed to investigate the role of amylin, H₂S, and connexin 43 in vascular dysfunction and enhanced ischemia–reperfusion (I/R)-induced myocardial injury in diabetic rats. A single dose of streptozotocin (65 mg/kg) was employed to induce diabetes mellitus. After 8 weeks, there was a significant decrease in the plasma levels of amylin, an increase in I/R injury to isolated hearts (increase in CK-MB and cardiac troponin release) on the Langendorff apparatus. Moreover, there was a significant impairment in vascular endothelium function as assessed by quantifying acetylcholine-induced relaxation in norepinephrine-precontracted mesenteric arteries. There was also a marked decrease in the expression of H₂S and connexin 43 in the hearts following I/R injury in diabetic rats. Treatment with amylin agonist, pramlintide (100 and 200 µg/kg), and H₂S donor, NaHS (10 and 20 μmol/kg) for 2 weeks improved the vascular endothelium function, abolished enhanced myocardial injury and restored the levels of H₂S along with connexin 43 in diabetic animals. However, pramlintide and NaHS failed to produce these effects the presence of gap junction blocker, carbenoxolone (20 and 40 mg/kg). Carbenoxolone also abolished the myocardial levels of connexin 43 without affecting the plasma levels of amylin and myocardial levels of H₂S. The decrease in the amylin levels with a consequent reduction in H₂S and connexin 43 may contribute to inducing vascular dysfunction and enhancing I/R-induced myocardial injury in diabetic rats.

Harnessing the Benefits of Endogenous Hydrogen Sulfide to Reduce Cardiovascular Disease

Cardiovascular disease is the leading cause of death in the U.S. While various studies have shown the beneficial impact of exogenous hydrogen sulfide (H₂S)-releasing drugs, few have demonstrated the influence of endogenous H₂S production. Modulating the predominant enzymatic sources of H₂S-cystathionine-β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase-is an emerging and promising research area. This review frames the discussion of harnessing endogenous H₂S within the context of a non-ischemic form of cardiomyopathy, termed diabetic cardiomyopathy, and heart failure. Also, we examine the current literature around therapeutic interventions, such as intermittent fasting and exercise, that stimulate H₂S production.

A novel H2S releasing-monastrol hybrid (MADTOH) inhibits L-type calcium channels

A new alleged monastrol-H₂S releasing hybrid, named MADTOH, was designed based on the structure of monastrol (M) and 5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione (ADTOH) and synthesized in 7.8% overall yield.

Natural products: The role and mechanism in low-density lipoprotein oxidation and atherosclerosis

Atherosclerosis is a chronic inflammatory, metabolic, and epigenetic disease, which leads to the life-threatening coronary artery disease. Emerging studies from bench to bedside have demonstrated the pivotal role of low-density lipoprotein (LDL) oxidation in the initiation and progression of atherosclerosis. This article hereby reviews oxidation mechanism of LDL, and the pro-atherogenic and biomarker role of oxidized LDL in atherosclerosis. We also review the pharmacological effects of several representative natural products (vitamin E, resveratrol, quercetin, probucol, tanshinone IIA, epigallocatechin gallate, and Lycopene) in protecting against LDL oxidation and atherosclerosis. Clinical and basic research supports the beneficial effects of these natural products in inhibiting LDL oxidation and preventing atherosclerosis, but the data are still controversial. This may be related to factors such as the population and the dosage and time of taking natural products involved in different studies. Understanding the mechanism of LDL oxidation and effect of oxidized LDL help researchers to find novel therapies against atherosclerosis.

The use of high-performance liquid chromatography with diode array detector for the determination of sulfide ions in human urine samples using pyrylium salts

Hydrogen sulfide is a toxic gas involved in the regulation of some essential biological processes. A novel, precise, accurate and rapid method based on high-performance liquid chromatography with diode array detection for the determination of sulfide ions in human urine sample is proposed. The method involves the derivatization of sulfide with pyrylium salts - (2,4,6-triphenylpyrylium hydrogensulfate(VI) (L1) and 4-[p-(N,N-dimethylamino)phenyl]-2,6-diphenylpyrylium chlorate(VII) (LN1). The separation occurs on InfinityLab Poroshell 120 EC C₁₈ column using acetonitrile and phosphate buffer as a mobile phase. The detectors utilized a wavelength of 371 or 580 nm. The calibration curves were linear in the range of 2-150 μmol L^-1 and 1-50 μmol L^-1 for L1 and LN1 derivatives, respectively. The samples were found to be stable from sample collection to final analysis. The method was successfully applied to samples from apparently healthy volunteers.

The slow releasing hydrogen sulfide donor GYY4137 reduces neointima formation upon FeCl3 injury of the carotid artery in mice

INTRODUCTION

Neointima formation is closely linked to vascular stenosis and occurs after endothelial damage. Hydrogen sulfide is an endogenous pleiotropic mediator with numerous positive effects on the cardio vascular system.

OBJECTIVE

This study evaluates the effect of the slow releasing hydrogen sulfide donor GYY4137 (GYY) on neointimal formation in vivo.

METHODS

The effect of GYY on neointimal formation in the carotid artery was studied in the FeCl3 injury model in GYY- or vehicle-treated mice. The carotid arteries were studied at days 7 and 21 after treatment by means of histology and immunohistochemistry for proliferating cell nuclear antigen (PCNA) and alpha smooth muscle actin (α-SMA).

RESULTS

GYY treatment significantly reduced the maximal diameter and the area of the newly formed neointima on both days 7 and 21 when compared to vehicle treatment. GYY additionally reduced the number of PCNA- and α-SMA-positive cells within the neointima on day 21 after FeCl3 injury of the carotid artery.

CONCLUSIONS

Summarizing, single treatment with the slow releasing hydrogen sulfide donor GYY reduced the extent of the newly formed neointima by affecting the cellular proliferation at the site of vascular injury.

The role of hydrogen sulphide signalling in macrophage activation

Hydrogen sulphide (H₂S) is the latest identified small gaseous mediator enabled by its lipophilic nature to freely permeate the biological membranes. Initially, H₂S was recognized by its roles in neuronal activity and vascular relaxation, which makes it an important molecule involved in paracrine signalling pathways. Recently, the immune regulatory function of gasotransmitters, H₂S in particular, is increasingly being appreciated. Endogenous H₂S level has been linked to macrophage activation, polarization and inflammasome formation. Mechanistically, H₂S‐induced protein S‐sulphydration suppresses several inflammatory pathways including NF‐κB and JNK signalling. Moreover, H₂S serves as a potent cellular redox regulator to modulate epigenetic alterations and to promote mitochondrial biogenesis in macrophages. Here in this review, we intend to summarize the recent advancements of H₂S studies in macrophages, and to discuss with focus on the therapeutic potential of H₂S donors by targeting macrophages. The feasibility of H₂S signalling component as a macrophage biomarker under disease conditions would be also discussed.

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.

Traditional Chinese medicine in cardiovascular drug discovery

In this virtual special issue entitled "Traditional Chinese Medicine in Cardiovascular Drug Discovery", a collection of 18 basic research, clinical research and review articles was published to highlight the therapeutic potential of traditional Chinese medicine (TCM) and their bioactive components in treating atherosclerosis, coronary artery disease, ischemic cardiomyopathy, heart failure and beyond.

Effects of drinking natural hydrogen sulfide (H2S) waters: a systematic review of in vivo animal studies

Natural waters containing originally hydrogen sulfide (H2S) gas with an S2-level at least 1 mg/L are classified as "sulfur waters" or "hydrogen sulfide waters." This systematic review aimed to evaluate in vivo experimental studies investigating the biological effects of natural H2S water drinking in healthy or with disease model laboratory animals. A comprehensive databases search (PubMed, Embase, Web of Science, and Google Scholar) was performed and PICOS criteria were used to assess eligibility. All relevant studies were identified, screened, and examined. The qualitative assessment was performed with the help of the SYRCLE Risk of Bias tool. A total of nine articles were included. The extracted data showed that ad libitum drinking of such waters by rats and mice exert beneficial effects on animal model of diabetes and glucose metabolism plus protective effects on diabetic cardiac, testicular, and nephrological complications as shown biochemically, histopathologically, and bio-molecularly. Additional effects were gastroprotection, antioxidant effects and improvement of intestinal physiology in healthy animals, reduction in general signs of murine model of colitis in mice, improvement in lipid metabolism and lipid-lowering effect, and positive interference with the enterohepatic cycle of the bile acids and biliary functions in hyperlipidemic rats. This systematic review provides preliminary insights into the "biological truth" about natural H2S waters and partly elucidates their potential therapeutic role in balneology and health resort medicine. However, it should be kept in mind that the retrieved preclinical data cannot be directly extrapolated to humans. Additionally, most of the included studies were rated for unclear risk of bias across all categories except random allocation, reflecting very poor reporting of methodological details. These limitations should be addressed when planning similar studies in the future. The question "can traditional hydropinic therapies or drinking cures with H2S waters at natural sulfur water spas/health resorts or natural (even artificial) H2S water consumption at home exert similar effects in humans?" remains to be clarified by clinical trials.

Metformin and Vascular Diseases: A Focused Review on Smooth Muscle Cell Function

Metformin has been used in diabetes for more than 60 years and has excellent safety in the therapy of human type 2 diabetes (T2D). There is growing evidence that the beneficial health effects of metformin are beyond its ability to improve glucose metabolism. Metformin not only reduces the incidence of cardiovascular diseases (CVD) in T2D patients, but also reduces the burden of atherosclerosis (AS) in pre-diabetes patients. Vascular smooth muscle cells (VSMCs) function is an important factor in determining the characteristics of the entire arterial vessel. Its excessive proliferation contributes to the etiology of several types of CVD, including AS, restenosis, and pulmonary hypertension. Current studies show that metformin has a beneficial effect on VSMCs function. Therefore, this review provides a timely overview of the role and molecular mechanisms by which metformin acts through VSMCs to protect CVD.