GYY4137 protects against myocardial ischemia and reperfusion injury by attenuating oxidative stress and apoptosis in rats

Therapeutic Potential of Hydrogen Sulfide in Ischemia and Reperfusion Injury

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

Static Cold Storage with Mitochondria-Targeted Hydrogen Sulfide Donor Improves Renal Graft Function in an Ex Vivo Porcine Model of Controlled Donation-after-Cardiac-Death Kidney Transplantation

The global donor kidney shortage crisis has necessitated the use of suboptimal kidneys from donors-after-cardiac-death (DCD). Using an ex vivo porcine model of DCD kidney transplantation, the present study investigates whether the addition of hydrogen sulfide donor, AP39, to University of Wisconsin (UW) solution improves graft quality. Renal pedicles of male pigs were clamped in situ for 30 min and the ureters and arteries were cannulated to mimic DCD. Next, both donor kidneys were nephrectomized and preserved by static cold storage in UW solution with or without AP39 (200 nM) at 4 °C for 4 h followed by reperfusion with stressed autologous blood for 4 h at 37 °C using ex vivo pulsatile perfusion apparatus. Urine and arterial blood samples were collected hourly during reperfusion. After 4 h of reperfusion, kidneys were collected for histopathological analysis. Compared to the UW-only group, UW+AP39 group showed significantly higher pO2 (p < 0.01) and tissue oxygenation (p < 0.05). Also, there were significant increases in urine production and blood flow rate, and reduced levels of urine protein, serum creatinine, blood urea nitrogen, plasma Na+ and K+, as well as reduced intrarenal resistance in the UW+AP39 group compared to the UW-only group. Histologically, AP39 preserved renal structure by reducing the apoptosis of renal tubular cells and immune cell infiltration. Our finding could lay the foundation for improved graft preservation and reduce the increasingly poor outcomes associated with DCD kidney transplantation.

Regulatory effects of trimetazidine in cardiac ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a tissue damage during reperfusion after an ischemic condition. I/R injury is induced by pathological cases including stroke, myocardial infarction, circulatory arrest, sickle cell disease, acute kidney injury, trauma, and sleep apnea. It can lead to increased morbidity and mortality in the context of these processes. Mitochondrial dysfunction is one of the hallmarks of I/R insult, which is induced via reactive oxygen species (ROS) production, apoptosis, and autophagy. MicroRNAs (miRNAs, miRs) are non-coding RNAs that play a main regulatory role in gene expression. Recently, there are evidence, which miRNAs are the major modulators of cardiovascular diseases, especially myocardial I/R injury. Cardiovascular miRNAs, specifically miR-21, and probably miR-24 and miR-126 have protective effects on myocardial I/R injury. Trimetazidine (TMZ) is a new class of metabolic agents with an anti-ischemic activity. It has beneficial effects on chronic stable angina by suppressing mitochondrial permeability transition pore (mPTP) opening. The present review study addressed the different mechanistic effects of TMZ on cardiac I/R injury. Online databases including Scopus, PubMed, Web of Science, and Cochrane library were assessed for published studies between 1986 and 2021. TMZ, an antioxidant and metabolic agent, prevents the cardiac reperfusion injury by regulating AMP-activated protein kinase (AMPK), cystathionine-γ-lyase enzyme (CSE)/hydrogen sulfide (H2S), and miR-21. Therefore, TMZ protects the heart against I/R injury by inducing key regulators such as AMPK, CSE/H2S, and miR-21.

H2S Donors with Cytoprotective Effects in Models of MI/R Injury and Chemotherapy-Induced Cardiotoxicity

Hydrogen sulfide (H2S) is an endogenous signaling molecule that greatly influences several important (patho)physiological processes related to cardiovascular health and disease, including vasodilation, angiogenesis, inflammation, and cellular redox homeostasis. Consequently, H2S supplementation is an emerging area of interest, especially for the treatment of cardiovascular-related diseases. To fully unlock the medicinal properties of hydrogen sulfide, however, the development and refinement of H2S releasing compounds (or donors) are required to augment its bioavailability and to better mimic its natural enzymatic production. Categorizing donors by the biological stimulus that triggers their H2S release, this review highlights the fundamental chemistry and releasing mechanisms of a range of H2S donors that have exhibited promising protective effects in models of myocardial ischemia-reperfusion (MI/R) injury and cancer chemotherapy-induced cardiotoxicity, specifically. Thus, in addition to serving as important investigative tools that further advance our knowledge and understanding of H2S chemical biology, the compounds highlighted in this review have the potential to serve as vital therapeutic agents for the treatment (or prevention) of various cardiomyopathies.

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.

S-nitrosylation of c-Jun N-terminal kinase mediates pressure overload-induced cardiac dysfunction and fibrosis

Cardiac fibrosis (CF) is an irreversible pathological process that occurs in almost all kinds of cardiovascular diseases. Phosphorylation-dependent activation of c-Jun N-terminal kinase (JNK) induces cardiac fibrosis. However, whether S-nitrosylation of JNK mediates cardiac fibrosis remains an open question. A biotin-switch assay confirmed that S-nitrosylation of JNK (SNO-JNK) increased significantly in the heart tissues of hypertrophic patients, transverse aortic constriction (TAC) mice, spontaneously hypertensive rats (SHRs), and neonatal rat cardiac fibroblasts (NRCFs) stimulated with angiotensin II (Ang II). Site to site substitution of alanine for cysteine in JNK was applied to determine the S-nitrosylated site. S-Nitrosylation occurred at both Cys116 and Cys163 and substitution of alanine for cysteine 116 and cysteine 163 (C116/163A) inhibited Ang II-induced myofibroblast transformation. We further confirmed that the source of S-nitrosylation was inducible nitric oxide synthase (iNOS). 1400 W, an inhibitor of iNOS, abrogated the profibrotic effects of Ang II in NRCFs. Mechanistically, SNO-JNK facilitated the nuclear translocation of JNK, increased the phosphorylation of c-Jun, and induced the transcriptional activity of AP-1 as determined by chromatin immunoprecipitation and EMSA. Finally, WT and iNOS^-/- mice were subjected to TAC and iNOS knockout reduced SNO-JNK and alleviated cardiac fibrosis. Our findings demonstrate an alternative mechanism by which iNOS-induced SNO-JNK increases JNK pathway activity and accelerates cardiac fibrosis. Targeting SNO-JNK might be a novel therapeutic strategy against cardiac fibrosis.

Necroptosis Inhibition by Hydrogen Sulfide Alleviated Hypoxia-Induced Cardiac Fibroblasts Proliferation via Sirtuin 3

Myocardial ischemia or hypoxia can induce myocardial fibroblast proliferation and myocardial fibrosis. Hydrogen sulfide (H₂S) is a gasotransmitter with multiple physiological functions. In our present study, primary cardiac fibroblasts were incubated with H₂S donor sodium hydrosulfide (NaHS, 50 μM) for 4 h followed by hypoxia stimulation (containing 5% CO₂ and 1% O₂) for 4 h. Then, the preventive effects on cardiac fibroblast proliferation and the possible mechanisms were investigated. Our results showed that NaHS reduced the cardiac fibroblast number, decreased the hydroxyproline content; inhibited the EdU positive ratio; and down-regulated the expressions of α-smooth muscle actin (α-SMA), the antigen identified by monoclonal antibody Ki67 (Ki67), proliferating cell nuclear antigen (PCNA), collagen I, and collagen III, suggesting that hypoxia-induced cardiac fibroblasts proliferation was suppressed by NaHS. NaHS improved the mitochondrial membrane potential and attenuated oxidative stress, and inhibited dynamin-related protein 1 (DRP1), but enhanced optic atrophy protein 1 (OPA1) expression. NaHS down-regulated receptor interacting protein kinase 1 (RIPK1) and RIPK3 expression, suggesting that necroptosis was alleviated. NaHS increased the sirtuin 3 (SIRT3) expressions in hypoxia-induced cardiac fibroblasts. Moreover, after SIRT3 siRNA transfection, the inhibitory effects on cardiac fibroblast proliferation, oxidative stress, and necroptosis were weakened. In summary, necroptosis inhibition by exogenous H₂S alleviated hypoxia-induced cardiac fibroblast proliferation via SIRT3.

H2S and Oxytocin Systems in Early Life Stress and Cardiovascular Disease

Today it is well established that early life stress leads to cardiovascular programming that manifests in cardiovascular disease, but the mechanisms by which this occurs, are not fully understood. This perspective review examines the relevant literature that implicates the dysregulation of the gasomediator hydrogen sulfide and the neuroendocrine oxytocin systems in heart disease and their putative mechanistic role in the early life stress developmental origins of cardiovascular disease. Furthermore, interesting hints towards the mutual interaction of the hydrogen sulfide and OT systems are identified, especially with regards to the connection between the central nervous and the cardiovascular system, which support the role of the vagus nerve as a communication link between the brain and the heart in stress-mediated cardiovascular disease.

Modulation of EndMT by Hydrogen Sulfide in the Prevention of Cardiovascular Fibrosis

Endothelial mesenchymal transition (EndMT) has been described as a fundamental process during embryogenesis; however, it can occur also in adult age, underlying pathological events, including fibrosis. Indeed, during EndMT, the endothelial cells lose their specific markers, such as vascular endothelial cadherin (VE-cadherin), and acquire a mesenchymal phenotype, expressing specific products, such as α-smooth muscle actin (α-SMA) and type I collagen; moreover, the integrity of the endothelium is disrupted, and cells show a migratory, invasive and proliferative phenotype. Several stimuli can trigger this transition, but transforming growth factor (TGF-β1) is considered the most relevant. EndMT can proceed in a canonical smad-dependent or non-canonical smad-independent manner and ultimately regulate gene expression of pro-fibrotic machinery. These events lead to endothelial dysfunction and atherosclerosis at the vascular level as well as myocardial hypertrophy and fibrosis. Indeed, EndMT is the mechanism which promotes the progression of cardiovascular disorders following hypertension, diabetes, heart failure and also ageing. In this scenario, hydrogen sulfide (H₂S) has been widely described for its preventive properties, but its role in EndMT is poorly investigated. This review is focused on the evaluation of the putative role of H₂S in the EndMT process.

Protective Effects of GYY4137 on Renal Ischaemia/Reperfusion Injury through Nrf2-Mediated Antioxidant Defence

INTRODUCTION/AIMS

Hydrogen sulfide (H2S) is considered to be the third most important endogenous gasotransmitter in organisms. GYY4137 is a long-acting donor for H2S, a gas transmitter that has been shown to prevent multi-organ damage in animal studies. We previously reported the effect of GYY4137 on cardiac ischaemia reperfusion injury (IRI) in diabetic mice. However, the role and mechanism of GYY4137 in renal IRI are poorly understood. The aims of this study were to determine whether GYY4137 can effectively alleviate the injury induced by renal ischaemia reperfusion and to explore its possible mechanism.

METHODS

Mice received right nephrectomy and clipping of the left renal pedicle for 45 min. GYY4137 was administered by intraperitoneal injection for 2 consecutive days before the operation. The model of hypoxia/reoxygenation injury was established in HK-2 cells, which were pre-treated with or without GYY4137. Renal histology, function, apoptosis, and oxidative stress were measured. Western blot was used to measure the target -protein after renal IRI.

RESULTS

The results indicated that GYY4137 had a clear protective effect on renal IRI as reflected by the attenuation of renal dysfunction, renal tubule injury, and apoptosis. Moreover, GYY4137 remarkably reduced renal IRI-induced oxidative stress. GYY4137 significantly elevated the nuclear translocation of nuclear factor-erythroid-2-related factor 2 (Nrf2) and the expression of antioxidant enzymes regulated by Nrf2, including SOD, HO-1, and NQO-1.

CONCLUSIONS

GYY4137 alleviates ischaemia reperfusion-induced renal injury through activating the antioxidant effect mediated by Nrf2 signalling.

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.

H2S- and NO-releasing gasotransmitter platform: A crosstalk signaling pathway in the treatment of acute kidney injury

Acute kidney injury (AKI) is a syndrome affecting most patients hospitalized due to kidney disease; it accounts for 15 % of patients hospitalized in intensive care units worldwide. AKI is mainly caused by ischemia and reperfusion (IR) injury, which temporarily obstructs the blood flow, increases inflammation processes and induces oxidative stress. AKI treatments available nowadays present notable disadvantages, mostly for patients with other comorbidities. Thus, it is important to investigate different approaches to help minimizing side effects such as the ones observed in patients subjected to the aforementioned treatments. Therefore, the aim of the current review is to highlight the potential of two endogenous gasotransmitters - hydrogen sulfide (H₂S) and nitric oxide (NO) - and their crosstalk in AKI treatment. Both H₂S and NO are endogenous signalling molecules involved in several physiological and pathophysiological processes, such as the ones taking place in the renal system. Overall, these molecules act by decreasing inflammation, controlling reactive oxygen species (ROS) concentrations, activating/inactivating pro-inflammatory cytokines, as well as promoting vasodilation and decreasing apoptosis, hypertrophy and autophagy. Since these gasotransmitters are found in gaseous state at environmental conditions, they can be directly applied by inhalation, or in combination with H₂S and NO donors, which are compounds capable of releasing these molecules at biological conditions, thus enabling higher stability and slow release of NO and H₂S. Moreover, the combination between these donor compounds and nanomaterials has the potential to enable targeted treatments, reduce side effects and increase the potential of H₂S and NO. Finally, it is essential highlighting challenges to, and perspectives in, pharmacological applications of H₂S and NO to treat AKI, mainly in combination with nanoparticulated delivery platforms.

The Interaction of the Endogenous Hydrogen Sulfide and Oxytocin Systems in Fluid Regulation and the Cardiovascular System

The purpose of this review is to explore the parallel roles and interaction of hydrogen sulfide (H2S) and oxytocin (OT) in cardiovascular regulation and fluid homeostasis. Their interaction has been recently reported to be relevant during physical and psychological trauma. However, literature reports on H2S in physical trauma and OT in psychological trauma are abundant, whereas available information regarding H2S in psychological trauma and OT in physical trauma is much more limited. This review summarizes recent direct and indirect evidence of the interaction of the two systems and their convergence in downstream nitric oxide-dependent signaling pathways during various types of trauma, in an effort to better understand biological correlates of psychosomatic interdependencies.

H2S counteracts proinflammatory effects of LPS through modulation of multiple pathways in human cells

BACKGROUND

Hydrogen sulfide donors reduce inflammatory signaling in vitro and in vivo. The biological effect mediated by H₂S donors depends on the kinetics of the gas release from the donor molecule. However, the molecular mechanisms of H₂S-induced immunomodulation were poorly addressed. Here, we studied the effect of two different hydrogen sulfide (H₂S)-producing agents on the generation of the LPS-induced inflammatory mediators. Importantly, we investigated the transcriptomic changes that take place in human cells after the LPS challenge, combined with the pretreatment with a slow-releasing H₂S donor-GYY4137.

METHODS

We investigated the effects of GYY4137 and sodium hydrosulfide on the release of proinflammatory molecules such as ROS, NO and TNF-α from LPS-treated human SH-SY5Y neuroblastoma and the THP-1 promonocytic cell lines. Transcriptomic and RT-qPCR studies using THP-1 cells were performed to monitor the effects of the GYY4137 on multiple signaling pathways, including various immune-related and proinflammatory genes after combined action of LPS and GYY4137.

RESULTS

The GYY4137 and sodium hydrosulfide differed in the ability to reduce the production of the LPS-evoked proinflammatory mediators. The pre-treatment with GYY4137 resulted in a drastic down-regulation of many TNF-α effectors that are induced by LPS treatment in THP-1 cells. Furthermore, GYY4137 pretreatment of LPS-exposed cells ameliorates the LPS-mediated induction of multiple pro-inflammatory genes and decreases expression of immunoproteasome genes. Besides, in these experiments we detected the up-regulation of several important pathways that are inhibited by LPS.

CONCLUSION

Based on the obtained results we believe that our transcriptomic analysis significantly contributes to the understanding of the molecular mechanisms of anti-inflammatory and cytoprotective activity of hydrogen sulfide donors, and highlights their potential against LPS challenges and other forms of inflammation.

The cystathionine γ-lyase/hydrogen sulfide pathway mediates the trimetazidine-induced protection of H9c2 cells against hypoxia/reoxygenation-induced apoptosis and oxidative stress

Objective:

Trimetazidine is a piperazine-derived metabolic agent. It exerts cardioprotective effects against myocardial ischemia/reperfusion (I/R) injury. In addition, studies confirm that the cystathionine γ-lyase (CSE)/hydrogen sulfide (H₂S) pathway serves a beneficent role in attenuating myocardial I/R injury. However, the underlying role of the CSE/H₂S pathway in the trimetazidine-induced protection against myocardial I/R injury remains elusive. Therefore, this study investigated whether trimetazidine ameliorates hypoxia/reoxygenation (H/R)-induced H9c2 cardiomyocyte injuries in an in vitro cell model of myocardial I/R injury, by enhancing the CSE/H₂S pathway.

Methods:

The H9c2 cell viability was determined with a cell counting Kit-8.

Results:

Trimetazidine significantly increased the cell viability and decreased lactate dehydrogenase (LDH) release in H/R-treated H9c2 cells. Additionally, trimetazidine increased the H₂S levels and the CSE mRNA and protein levels, promoting the CSE/H₂S pathway under H/R conditions. The inhibition of the CSE/H₂S pathway, induced by transfection with specific siRNA against human CSE (si-CSE), eliminated the trimetazidine-induced upregulation of cell viability, downregulation of LDH release, increase of caspase-3 activity and apoptosis regulator BAX expression, and the decrease of apoptosis regulator Bcl-2 expression, which suggests involvement of the CSE/H₂S pathway in trimetazidine-induced cardioprotection. Furthermore, trimetazidine mitigated the H/R-induced increase in reactive oxygen species production and NADPH oxidase 2 expression, and decrease in superoxide dismutase activity and glutathione level, in H9c2 cells. These effects were also reversed by si-CSE.

Conclusion:

This study revealed that the CSE/H₂S pathway mediates the trimetazidine-induced protection of H9c2 cardiomyocytes against H/R-induced damage by inhibiting apoptosis and oxidative stress.

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

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

Development of a hydrolysis-based small-molecule hydrogen selenide (H2Se) donor

Selenium is essential to human physiology and has recently shown potential in the treatment of common pathophysiological conditions ranging from arsenic poisoning to cancer. Although the precise metabolic and chemical pathways of selenium incorporation into biomolecules remain somewhat unclear, many such pathways proceed through hydrogen selenide (H2Se/HSe-) formation. Despite this importance, well-characterized chemistry that enables H2Se release under controlled conditions remains lacking. Motivated by this need, we report here the development of a hydrolysis-based H2Se donor (TDN1042). Utilizing 31P and 77Se NMR experiments, we demonstrate the pH dependence of H2Se release and characterize observed reaction intermediates during the hydrolysis mechanism. Finally, we confirm H2Se release using electrophilic trapping reagents, which not only demonstrates the fidelity of this donor platform but also provides an efficient method for investigating future H2Se donor motifs. Taken together, this work provides an early example of an H2Se donor that functions through a well-defined and characterized mechanism.

Inhibitor 1 of Protein Phosphatase 1 Regulates Ca2+/Calmodulin-Dependent Protein Kinase II to Alleviate Oxidative Stress in Hypoxia-Reoxygenation Injury of Cardiomyocytes

Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), regulated by inhibitor 1 of protein phosphatase 1 (I1PP1), is vital for maintaining cardiovascular homeostasis. However, the role and mechanism of I1PP1 against hypoxia-reoxygenation (H/R) injury in cardiomyocytes remain a question. In our study, after I1PP1 overexpression by adenovirus infection in the neonatal cardiomyocytes followed by hypoxia for 4 h and reoxygenation for 12 h, the CaMKIIδ alternative splicing subtype, ATP content, and lactate dehydrogenase (LDH) release were determined. CaMKII activity was evaluated by phosphoprotein phosphorylation at Thr17 (p-PLB Thr17), CaMKII phosphorylation (p-CaMKII), and CaMKII oxidation (ox-CaMKII). Reactive oxygen species (ROS), mitochondrial membrane potential, dynamin-related protein 1 (DRP1), and optic atrophy 1 (OPA1) expressions were assessed. Our study verified that I1PP1 overexpression attenuated the CaMKIIδ alternative splicing disorder; suppressed PLB phosphorylation at Thr17, p-CaMKII, and ox-CaMKII; decreased cell LDH release; increased ATP content; attenuated ROS production; increased mitochondrial membrane potential; and decreased DRP1 expression but increased OPA1 expression in the cardiomyocytes after H/R. Contrarily, CaMKIIδ alternative splicing disorder, LDH release, ATP reduction, and ROS accumulation were aggravated after H/R injury with the I1PP1 knockdown. Collectively, I1PP1 overexpression corrected disorders of CaMKIIδ alternative splicing, inhibited CaMKII phosphorylation, repressed CaMKII oxidation, suppressed ROS production, and attenuated cardiomyocyte H/R injury.

GYY4137 Attenuates Sodium Deoxycholate-Induced Intestinal Barrier Injury Both In Vitro and In Vivo

Objectives

Substantial studies have demonstrated that an elevated concentration of deoxycholic acid (DCA) in the colonic lumen may play a critical role in the pathogenesis of intestinal barrier dysfunction and inflammatory bowel disease (IBD). The purpose of this study was to investigate the protective effects of GYY4137, as a novel and synthetic H₂S donor, on the injury of intestinal barrier induced by sodium deoxycholate (SDC) both in vivo and in vitro.

Methods

In this study, Caco-2 monolayers and mouse models with high SDC concentration in the lumen were used to study the effect of GYY4137 on intestinal barrier dysfunction induced by SDC and its underlying mechanisms.

Results

In Caco-2 monolayers, a short period of addition of SDC increased the permeability of monolayers obviously, changed distribution of tight junctions (TJs), and improved the phosphorylation level of myosin light chain kinase (MLCK) and myosin light chain (MLC). However, pretreatment with GYY4137 markedly ameliorated the SDC-induced barrier dysfunction. Being injected with GYY4137 could enable mice to resist the SDC-induced injury of the intestinal barrier. Besides, GYY4137 promoted the recovery of the body weight and intestinal barrier histological score of mice with the gavage of SDC. GYY4137 also attenuated the decreased expression level of TJs in mice treated with SDC.

Conclusion

Taken together, this research suggests that GYY4137 preserves the intestinal barrier from SDC-induced injury via suppressing the activation of P-MLCK-P-MLC2 signaling pathway and increasing the expression level of tight junctions.

Hydrogen sulphide-induced hypometabolism in human-sized porcine kidneys

Background

Since the start of organ transplantation, hypothermia-forced hypometabolism has been the cornerstone in organ preservation. Cold preservation showed to protect against ischemia, although post-transplant injury still occurs and further improvement in preservation techniques is needed. We hypothesize that hydrogen sulphide can be used as such a new preservation method, by inducing a reversible hypometabolic state in human sized kidneys during normothermic machine perfusion.

Methods

Porcine kidneys were connected to an ex-vivo isolated, oxygen supplemented, normothermic blood perfusion set-up. Experimental kidneys (n = 5) received a 85mg NaHS infusion of 100 ppm and were compared to controls (n = 5). As a reflection of the cellular metabolism, oxygen consumption, mitochondrial activity and tissue ATP levels were measured. Kidney function was assessed by creatinine clearance and fractional excretion of sodium. To rule out potential structural and functional deterioration, kidneys were studied for biochemical markers and histology.

Results

Hydrogen sulphide strongly decreased oxygen consumption by 61%, which was associated with a marked decrease in mitochondrial activity/function, without directly affecting ATP levels. Renal biological markers, renal function and histology did not change after hydrogen sulphide treatment.

Conclusion

In conclusion, we showed that hydrogen sulphide can induce a controllable hypometabolic state in a human sized organ, without damaging the organ itself and could thereby be a promising therapeutic alternative for cold preservation under normothermic conditions in renal transplantation.

A Review of Hydrogen Sulfide Synthesis, Metabolism, and Measurement: Is Modulation of Hydrogen Sulfide a Novel Therapeutic for Cancer?

Significance: Hydrogen sulfide (H2S) has been recognized as the third gaseous transmitter alongside nitric oxide and carbon monoxide. In the past decade, numerous studies have demonstrated an active role of H2S in the context of cancer biology. Recent Advances: The three H2S-producing enzymes, namely cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3MST), have been found to be highly expressed in numerous types of cancer. Moreover, inhibition of CBS has shown anti-tumor activity, particularly in colon cancer, ovarian cancer, and breast cancer, whereas the consequence of CSE or 3MST inhibition remains largely unexplored in cancer cells. Intriguingly, H2S donation at high amounts or a long time duration has also been observed to induce cancer cell apoptosis in vitro and in vivo while sparing noncancerous fibroblast cells. Therefore, a bell-shaped model has been proposed to explain the role of H2S in cancer development. Specifically, endogenous H2S or a relatively low level of exogenous H2S may exhibit a pro-cancer effect, whereas exposure to H2S at a higher amount or for a long period may lead to cancer cell death. This indicates that inhibition of H2S biosynthesis and H2S supplementation serve as two distinct ways for cancer treatment. This paradoxical role of H2S has stimulated the enthusiasm for the development of novel CBS inhibitors, H2S donors, and H2S-releasing hybrids. Critical Issues: A clear relationship between H2S level and cancer progression remains lacking. The possibility that the altered levels of these byproducts have influenced the cell viability of cancer cells has not been excluded in previous studies when modulating H2S producing enzymes. Future Directions: The consequence of CSE or 3MST inhibition in cancer cells need to be examined in the future. Better portrayal of the crosstalk among these gaseous transmitters may not only lead to an in-depth understanding of cancer progression but also shed light on novel strategies for cancer therapy.

The H2S-Releasing Naproxen Derivative ATB-346 and the Slow-Release H2S Donor GYY4137 Reduce Intestinal Inflammation and Restore Transit in Postoperative Ileus

Objective: Intestinal inflammation triggers postoperative ileus (POI), commonly seen after abdominal surgery and characterized by impaired gastrointestinal transit; when prolonged, this leads to increased morbidity. Hydrogen sulfide (H2S) is recognized as an important mediator of many (patho)physiological processes, including inflammation, and is now investigated for anti-inflammatory application. Therefore, the aim of this study was to investigate the effect of the H2S-releasing naproxen derivative ATB-346, developed to reduce gastrointestinal injury by naproxen, and the slow-release H2S donor GYY4137 on intestinal inflammation and delayed gastrointestinal transit in murine POI. Methods: C57Bl6J mice were fasted for 6 h, anesthetized and after laparotomy, POI was induced by compressing the small intestine with two cotton applicators for 5 min (intestinal manipulation; IM). GYY4137 (50 mg/kg, intraperitoneally), ATB-346 (16 mg/kg, intragastrically) or naproxen (10 mg/kg, intragastrically) were administered 1 h before IM. At 24 h postoperatively, gastrointestinal transit was assessed via fluorescent imaging, and mucosa-free muscularis segments were prepared for later analysis. Inflammatory parameters and activity of inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX)-2 were measured. Histological examination of whole tissue sections was done on hematoxylin-eosin stained slides. Results: Pre-treatment with GYY4137 (geometric center; GC: 7.6 ± 0.5) and ATB-346 (GC: 8.4 ± 0.3) prevented the delayed transit induced by IM (GC: 3.6 ± 0.5 vs. 9.0 ± 0.4 in non-operated controls) while naproxen only partially did (GC: 5.9 ± 0.5; n = 8 for all groups). GYY4137 and ATB-346 significantly reduced the IM-induced increase in muscular myeloperoxidase (MPO) activity and protein levels of interleukin (IL)-6, IL-1β and monocyte chemotactic protein 1; the reduction by naproxen was less pronounced and only reached significance for MPO activity and IL-6 levels. All treatments significantly reduced the increase in COX-2 activity caused by IM, whereas only GYY4137 significantly reduced the increase in iNOS activity. Naproxen treatment caused significant histological damage of intestinal villi. Conclusion: The study shows that naproxen partially prevents POI, probably through its inhibitory effect on COX-2 activity. Both ATB-346 and GYY4137 were more effective, the result with GYY4137 showing that H2S per se can prevent POI.

Controlled-releasing hydrogen sulfide donor based on dual-modal iron oxide nanoparticles protects myocardial tissue from ischemia-reperfusion injury

BACKGROUND

Hydrogen sulfide (H2S) has shown promising therapeutic benefits in reversing a variety of pathophysiological processes in cardiovascular system, including myocardial ischemia-reperfusion (IR) injury. However, the achievement of controlled and sustained release of H2S has been a technical bottleneck that limits the clinical application of the gas molecule.

METHODS

The current study describes the development of mesoporous iron oxide nanoparticles (MIONs) which were loaded with diallyl trisulfide (DATS), a H2S donor compound, and calibrated by stimulated Raman scattering/transient absorption.

RESULTS

The synthesized MIONs were characterized with excellent mesoporosity and a narrow size distribution, which enabled them to slow down the release of H2S to a suitable rate and prolong the plateau period. The controlled-release feature of DATS-MIONs resulted in little adverse effect both in vitro and in vivo, and their protective effect on the heart tissue that underwent IR injury was observed in the mouse model of myocardial ischemia. The rapid biodegradation of DATS-MIONs was induced by Kupffer cells, which were specialized macrophages located in the liver and caused limited hepatic metabolic burden.

CONCLUSION

The sustained-release pattern and excellent biocompatibility make DATS-MIONs a promising H2S donor for research and medical purposes.

Protective Smell of Hydrogen Sulfide and Polysulfide in Cisplatin-Induced Nephrotoxicity

Though historically known as a toxic gas, hydrogen sulfide (H₂S) has displayed a new face as the third endogenous gaseous signaling molecule after nitric oxide (NO) and carbon monoxide (CO). Here in this review, we survey the role and therapeutic potential of H₂S in cisplatin-induced nephrotoxicity. Specifically, reduction of H₂S by cystathionine γ-lyase (CSE) downregulation upon cisplatin treatment may contribute to cisplatin-induced renal cell injury, possibly by augmentation of endogenous reactive oxygen species (ROS) production, while H₂S donation may prevent subsequent renal dysfunction by inhibiting NADPH oxidase activation. Intriguingly, H₂S slow-releasing compound GYY4137 seems to increase the anticancer activity of cisplatin, at least in several cancer cell lines, and this is probably due to its own anticancer effect. However, the efficacy of H₂S donors in tumor-bearing animals remains to be tested in terms of renal protection and cancer inhibition after receiving cisplatin. Furthermore, accumulative evidence regarding usage of polysulfide, a novel H₂S derived molecule, in the therapy of cisplatin-induced nephrotoxicity, was also summarized.

H 2S protects against diabetes-accelerated atherosclerosis by preventing the activation of NLRP3 inflammasome

Hydrogen sulfide (H ₂S) is an important messenger for its strong anti-inflammatory effects, which may be involved in multiple cardiovascular diseases. In our previous study, we revealed that H ₂S attenuated diabetes-accelerated atherosclerosis through suppressing oxidative stress. Here we report that GYY4137, a H ₂S donor, reduced the plaque formation of aortic roots and the levels of both intercellular cell adhesion molecule 1 (ICAM1) and vascular cell adhesion molecule 1 (VCAM1) in diabetes-accelerated atherosclerotic cells and mouse models. The inflammatory factors of TNF-α, IL-1β, IL-6, and MCP1 were also significantly reduced by GYY4137. Mechanically, GYY4137 suppressed the activation of pyrin domain containing protein 3 (NLRP3) inflammasome in diabetes-accelerated atherosclerosis conditions. Upon knockdown of NLRP3, the increase of ICAM1 and VCAM1 caused by high glucose and oxLDL could be reversed, indicating that H ₂S protected the endothelium by inhibiting the activity of NLRP3 inflammasome. In conclusion, our study indicates that GYY4137 effectively protects against the development of diabetes-accelerated atherosclerosis by inhibiting inflammasome activation.

Interaction of the hydrogen sulfide system with the oxytocin system in the injured mouse heart

Background

Both the hydrogen sulfide/cystathionine-γ-lyase (H₂S/CSE) and oxytocin/oxytocin receptor (OT/OTR) systems have been reported to be cardioprotective. H₂S can stimulate OT release, thereby affecting blood volume and pressure regulation. Systemic hyper-inflammation after blunt chest trauma is enhanced in cigarette smoke (CS)-exposed CSE^−/− mice compared to wildtype (WT). CS increases myometrial OTR expression, but to this point, no data are available on the effects CS exposure on the cardiac OT/OTR system. Since a contusion of the thorax (Txt) can cause myocardial injury, the aim of this post hoc study was to investigate the effects of CSE^−/− and exogenous administration of GYY4137 (a slow release H₂S releasing compound) on OTR expression in the heart, after acute on chronic disease, of CS exposed mice undergoing Txt.

Methods

This study is a post hoc analysis of material obtained in wild type (WT) homozygous CSE^−/− mice after 2-3 weeks of CS exposure and subsequent anesthesia, blast wave-induced TxT, and surgical instrumentation for mechanical ventilation (MV) and hemodynamic monitoring. CSE^−/− animals received a 50 μg/g GYY4137-bolus after TxT. After 4h of MV, animals were exsanguinated and organs were harvested. The heart was cut transversally, formalin-fixed, and paraffin-embedded. Immunohistochemistry for OTR, arginine-vasopressin-receptor (AVPR), and vascular endothelial growth factor (VEGF) was performed with naïve animals as native controls.

Results

CSE^−/− was associated with hypertension and lower blood glucose levels, partially and significantly restored by GYY4137 treatment, respectively. Myocardial OTR expression was reduced upon injury, and this was aggravated in CSE^−/−. Exogenous H₂S administration restored myocardial protein expression to WT levels.

Conclusions

This study suggests that cardiac CSE regulates cardiac OTR expression, and this effect might play a role in the regulation of cardiovascular function.

Role of Hydrogen Sulfide in NRF2- and Sirtuin-Dependent Maintenance of Cellular Redox Balance

Hydrogen sulfide (H₂S) has arisen as a critical gasotransmitter signaling molecule modulating cellular biological events related to health and diseases in heart, brain, liver, vascular systems and immune response. Three enzymes mediate the endogenous production of H₂S: cystathione β-synthase (CBS), cystathione γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST). CBS and CSE localizations are organ-specific. 3-MST is a mitochondrial and cytosolic enzyme. The generation of H₂S is firmly regulated by these enzymes under normal physiological conditions. Recent studies have highlighted the role of H₂S in cellular redox homeostasis, as it displays significant antioxidant properties. H₂S exerts antioxidant effects through several mechanisms, such as quenching reactive oxygen species (ROS) and reactive nitrogen species (RNS), by modulating cellular levels of glutathione (GSH) and thioredoxin (Trx-1) or increasing expression of antioxidant enzymes (AOE), by activating the transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2). H₂S also influences the activity of the histone deacetylase protein family of sirtuins, which plays an important role in inhibiting oxidative stress in cardiomyocytes and during the aging process by modulating AOE gene expression. This review focuses on the role of H₂S in NRF2 and sirtuin signaling pathways as they are related to cellular redox homeostasis.

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

Cardiovascular disease is the main cause of death worldwide, but its pathogenesis is not yet clear. Hydrogen sulfide (H₂S) is considered to be the third most important endogenous gasotransmitter in the organism after carbon monoxide and nitric oxide. It can be synthesized in mammalian tissues and can freely cross the cell membrane and exert many biological effects in various systems including cardiovascular system. More and more recent studies have supported the protective effects of endogenous H₂S and exogenous H₂S-releasing compounds (such as NaHS, Na₂S, and GYY4137) in cardiovascular diseases, such as cardiac hypertrophy, heart failure, ischemia/reperfusion injury, and atherosclerosis. Here, we provided an up-to-date overview of the mechanistic actions of H₂S as well as the therapeutic potential of various classes of H₂S donors in treating cardiovascular diseases.

Characterization and Biological Activity of a Hydrogen Sulfide-Releasing Red Light-Activated Ruthenium(II) Complex

Hydrogen sulfide (H₂S) is a biological gasotransmitter that has been employed for the treatment of ischemia-reperfusion injury. Despite its therapeutic value, the implementation of this gaseous molecule for this purpose has required H₂S-releasing prodrugs for effective intracellular delivery. The majority of these prodrugs, however, spontaneously release H₂S via uncontrolled hydrolysis. Here, we describe a Ru(II)-based H₂S-releasing agent that can be activated selectively by red light irradiation. This compound operates in living cells, increasing intracellular H₂S concentration only upon irradiation with red light. Furthermore, the red light irradiation of this compound protects H9c2 cardiomyoblasts from an in vitro model of ischemia-reperfusion injury. These results validate the use of red light-activated H₂S-releasing agents as valuable tools for studying the biology and therapeutic utility of this gasotransmitter.

Metformin Protects against H2O2-Induced Cardiomyocyte Injury by Inhibiting the miR-1a-3p/GRP94 Pathway

Ischemia-reperfusion (I/R) injury is a major side effect of the reperfusion treatment of the ischemic heart. Few therapies are available for the effective prevention of this injury caused by the oxidative stress-induced cardiomyocyte apoptosis. Metformin was shown to have a potential cardiac protective effect and ability to reduce cardiac events, but the exact mechanism remains unclear. Here, we aimed to confirm and investigate the mechanisms underlying potential metformin activity against I/R injury in response to oxidative stress. We determined that the expression of miR-1a-3p was significantly increased in neonatal rat ventricular cells (NRVCs), which were exposed to H₂O₂in vitro and in the hearts of mice that underwent the I/R injury. MiR-1a-3p was shown to target the 3′ UTR of GRP94, which results in the accumulation of un- or misfolded proteins, leading to the endoplasmic reticulum (ER) stress. The obtained results demonstrated that C/EBP β directly induces the upregulation of miR-1a-3p by binding to its promoter. Furthermore, as a direct allosteric AMPK activator, metformin was shown to activate AMPK and significantly reduce C/EBP β and miR-1a-3p levels compared with those in the control group. In conclusion, metformin protects cardiomyocytes against H₂O₂ damage through the AMPK/C/EBP β/miR-1a-3p/GRP94 pathway, which indicates that metformin may be applied for the treatment of I/R injury.

Effect of H2S on gastric ischemia-reperfusion injury in rats

AIM

To assess the effect of H₂S on oxidative stress in gastric mucosal injury induced by gastric ischemia-reperfusion (GI-R) in rats.

METHODS

GI-R was induced in rats by clamping the celiac artery for 30 min followed by 1 h reperfusion. Based on this, the rats were intraperitoneally pre-injected with different concentrations of NaHS for 14 d. Image J software and HE staining were employed to analyze the gastric mucosal damage area and deep damage, respectively. Oxidative stress indexes of the gastric mucosa were detected using commercial kits and Western blot.

RESULTS

The effects of different concentrations of NaHS on gastric mucosal injury induced by GI-R were different. Pretreatment with 10 μmol/L NaHS significantly reduced the area and depth of gastric mucosal injury induced by GI-R, with no effect on plasma H₂S. Compared with the GI-R group, pretreatment with NaHS significantly decreased the levels of malondialdehyde and H₂O₂ as well as the expression of XOD, gp91phox, and p67phox, but increased the level of reduced glutathione and the activity of SOD.

CONCLUSION

Exogenous H₂S can protect the gastric mucosa by reducing oxidative stress induced by GI-R.

Protein S-sulfhydration by hydrogen sulfide in cardiovascular system

Hydrogen sulfide (H2 S), independently of any specific transporters, has a number of biological effects on the cardiovascular system. However, until now, the detailed mechanism of H2 S was not clear. Recently, a novel post-translational modification induced by H2 S, named S-sulfhydration, has been proposed. S-sulfhydration is the chemical modification of specific cysteine residues of target proteins by H2 S. There are several methods for detecting S-sulfhydration, such as the modified biotin switch assay, maleimide assay with fluorescent thiol modifying regents, tag-switch method and mass spectrometry. H2 S induces S-sulfhydration on enzymes or receptors (such as p66Shc, phospholamban, protein tyrosine phosphatase 1B, mitogen-activated extracellular signal-regulated kinase 1 and ATP synthase subunit α), transcription factors (such as specific protein-1, kelch-like ECH-associating protein 1, NF-κB and interferon regulatory factor-1), and ion channels (such as voltage-activated Ca2+ channels, transient receptor potential channels and ATP-sensitive K+ channels) in the cardiovascular system. Although significant progress has been achieved in delineating the role of protein S-sulfhydration by H2 S in the cardiovascular system, more proteins with detailed cysteine sites of S-sulfhydration as well as physiological function need to be investigated in further studies. This review mainly summarizes the role and possible mechanism of S-sulfhydration in the cardiovascular system. The S-sulfhydrated proteins may be potential novel targets for therapeutic intervention and drug design in the cardiovascular system, which may accelerate the development and application of H2 S-related drugs in the future.

LINKED ARTICLES

This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Cardioprotection of tilianin ameliorates myocardial ischemia-reperfusion injury: Role of the apoptotic signaling pathway

Our previous research demonstrated that tilianin protects the myocardium in a myocardial ischemia reperfusion injury (MIRI) rat model and has prominent pharmacological potential as a cardiovascular drug. Our study aimed to investigate the molecular signaling implicated in the improvement of myocardial survival induced by tilianin, a flavonoid antioxidant. Tilianin (2.5, 5, and 10 mg/kg/d) or saline was orally administered to rats for 14 days. On the 15th day, ischemia was induced by ligating the left anterior descending artery for 45 min, followed by 4 h of reperfusion. The levels of MIRI-induced serum myocardial enzymes and cardiomyocyte apoptosis as well as infarct size were examined to assess the cardioprotective effects. Cardiac tissues were collected for western blot analyses to determine the protein expression of anti-apoptotic signaling molecules. In MIRI-treated rats, our results revealed that pre-administration of high dose-tilianin the reduced release of LDH, MDA, and CK-MB and increased the plasma SOD level, and significantly attenuated the infarct size. Western blot analysis showed that a remarkable rise in expression of Bcl-2 and XIAP, and decline in expression of Bax, Smac/Diablo, HtrA2/Omi, cleaved caspase-3, caspase-7 and caspase-9 was observed in the myocardium. The apoptosis index of cardiomyocytes further supports the cardioprotective effect of tilianin. Additionally, compared with the MIRI model group, pretreatment with high dose-tilianin group upregulated phosphorylated Akt and PI3K. In contrast, using the PI3K inhibitor LY294002 to block Akt activation effectively inhibited the protective effects of tilianin against MIRI. Tilianin pretreatment was beneficial for activating the PI3K/Akt signaling pathway and inhibiting myocardial apoptosis.

Sulfhydration-associated phosphodiesterase 5A dimerization mediates vasorelaxant effect of hydrogen sulfide

The study was designed to examine if the vasorelaxant effect of hydrogen sulfide was mediated by sulfhydration-associated phosphodiesterase (PDE) 5A dimerization. The thoracic aorta of rat was separated and the vasorelaxant effects were examined with in vitro vascular perfusion experiments. The dimerization and sulfhydration of PDE 5A and soluble guanylatecyclase (sGC) were measured. PDE 5A and protein kinase G (PKG) activities were tested. Intracellular cGMP content was detected by enzyme-linked immunosorbent assay (ELISA). The results showed that NaHS relaxed isolated rat vessel rings at an EC50 of (1.79 ± 0.31)×10-5mol/L, associated with significantly increased PKG activity and cGMP content in vascular tissues. Sulfhydration of sGC β1 was increased, while the levels of sGC αβ1 dimers were apparently decreased after incubation with NaHS in vascular tissues. Moreover, PDE 5A homodimers were markedly decreased, and accordingly the PDE 5A activity demonstrated by the content of 5'-GMP was significantly decreased after incubation with NaHS or GYY4137. Mechanistically, both NaHS and GYY4137 significantly enhanced the PDE 5A sulfhydration in vascular tissues. DTT partially abolished the effects of NaHS on PDE 5A activity, cGMP content and vasorelaxation. Therefore, the present study for the first time suggested that H2S exerted vasorelaxant effect probably via sulfhydration-associated PDE 5A dimerization.

miR-19b attenuates H2O2-induced apoptosis in rat H9C2 cardiomyocytes via targeting PTEN

Myocardial ischemia-reperfusion (I-R) injury lacks effective treatments. The miR-17-92 cluster plays important roles in regulating proliferation, apoptosis, cell cycle and other pivotal processes. However, their roles in myocardial I-R injury are largely unknown. In this study, we found that miR-19b was the only member of the miR-17-92 cluster that was downregulated in infarct area of heart samples from a murine model of I-R injury. Meanwhile, downregulation of miR-19b was also detected in H₂O₂-treated H9C2 cells in vitro mimicking oxidative stress occurring during myocardial I-R injury. Using flow cytometry and Western blot analysis, we found that overexpression of miR-19b decreased H₂O₂-induced apoptosis and improved cell survival, while downregulation of that had inverse effects. Furthermore, PTEN was negatively regulated by miR-19b at the protein level while silencing PTEN could completely block the aggravated impact of miR-19b inhibitor on H₂O₂-induced apoptosis in H9C2 cardiomyocytes, indicating PTEN as a downstream target of miR-19b controlling H₂O₂-induced apoptosis. These data indicate that miR-19b overexpression might be a novel therapy for myocardial I-R injury.

An Update on AMPK in Hydrogen Sulfide Pharmacology

Hydrogen sulfide (H₂S), the third bio-active gasotransmitter, is produced endogenously and tightly involved in the pathogenesis and treatment for various diseases. Adenosine 5′-monophosphate-activated protein kinase (AMPK) plays a paramount role in maintaining cellular energetic balance. Increasing evidences have also suggested AMPK as a novel modulator in multiple pathological conditions. In this paper, we will review the biological principles of H₂S and AMPK, and most importantly, the recent discoveries regarding AMPK-mediated pharmacological actions of H₂S. Emphasis will be laid on AMPK/H₂S interactions in the cardiovascular system, autophagy, diabetic complications, and inflammation. In most cases described in this article, by promoting AMPK activation, H₂S exerts cytoprotective effects or therapeutic potentials, though there remain some controversies before we can fully understand the involved mechanisms. Further researches are in need to investigate more closely any relationship between H₂S and AMPK, and to put forward the development of H₂S donors for clinical application.

The protective effects of GYY4137 on ipsilateral testicular injury in experimentally varicocele-induced rats

The aim of the present study was to evaluate whether morpholin-4-ium 4 methoxyphenyl (morpholino) phosphonodithioate (GYY4137) exhibits a protective effect on ipsilateral testicular injury in experimentally varicocele (VC)-induced rats. A total of 48 rats were randomly divided into the following 6 groups (n=8 each): Group A (control group); group B (sham group); group C (VC group); group D (VC group administered 5 mg/kg/day GYY4137); group E (VC group administered 10 mg/kg/day GYY4137) and group F (VC group administered 20 mg/kg/day GYY4137). Indicators of oxidative stress, apoptosis and inflammation were measured to evaluate the effect of GYY4137 on ipsilateral testicular injury. Compared with groups A and B, rats in group C exhibited severe histological changes and an increase in oxidative stress, apoptosis and inflammation. By contrast, amelioration of testicular damage was evident in the group D, E and F that were treated with GYY4137. These results demonstrate that GYY4137 may be a promising therapy to treat VC as it alleviates oxidative stress, apoptosis and inflammation in experimentally VC-induced rats.

Beyond a Gasotransmitter: Hydrogen Sulfide and Polysulfide in Cardiovascular Health and Immune Response

SIGNIFICANCE

Hydrogen sulfide (H₂S) metabolism leads to the formation of oxidized sulfide species, including polysulfide, persulfide, and others. Evidence is emerging that many biological effects of H₂S may indeed be due to polysulfide and persulfide activation of signaling pathways and reactivity with discrete small molecules. Recent Advances: Exogenous oxidized sulfide species, including polysulfides, are more reactive than H₂S with a wide range of molecules. Importantly, endogenous polysulfide and persulfide formation has been reported to occur via transsulfuration enzymes, cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS).

CRITICAL ISSUES

In light of the recent understanding of oxidized sulfide metabolite formation and reactivity, comparatively few studies have been reported comparing cellular biological and in vivo effects of H₂S donors versus polysulfide and persulfide donors. Likewise, it is equally unclear when, how, and to what extent persulfide and polysulfide formation occurs in vivo under pathophysiological conditions.

FUTURE DIRECTIONS

Additional studies regarding persulfide and polysulfide formation and molecular reactions are needed in nearly all aspects of biology to better understand how sulfide metabolites contribute to key chemical biology reactions involved in cardiovascular health and immune responses. Antioxid. Redox Signal. 27, 634-653.

Irisin attenuates H2O2-induced apoptosis in cardiomyocytes via microRNA-19b/AKT/mTOR signaling pathway

Irisin, a novel muscle-secreted peptide, has been proposed to play a potential role in improving myocardial remodeling that leads to impaired myocardial function and heart failure. It has been reported that controlling reactive oxygen species (ROS) exposure could increase cardiomyocyte survival and prevent pathological remodeling of the myocardium. Therefore, we aimed to determine the potential protective effects of Irisin pretreatment against ROS in cardiomyocytes and explored the potential mechanisms. H9c2 cells that were subjected to H₂O₂ in vitro were used to mimic myocardial remodeling. Then, the effects of Irisin on myocardial cell proliferation, apoptosis and cellular ROS levels were evaluated during this process by using MTT assay, flow cytometry analysis and 2'7'-Dichloro fluoresc in diacetate (DCFH-DA). In order to determine whether Irisin could regulate any microRNA (miRNA) during this process, six miRNAs that are known to be involved in apoptosis of cardiomyocytes were assessed by qRT-PCR. The protective effects of Irisin on cardiomyocytes mediated by miR-19b were evaluated by detecting cell proliferation and apoptosis. In addition, the potential target of miR-19b was predicted with bioinformatics tools and verified using dual-luciferase reporter assay. Finally, the protein levels of members of the phosphatidylinositol 3-kinase (PI3K)/Akt/signaling pathway were also examined by Western Blot. Our study showed that Irisin treatment improved H₂O₂-induced cell viability and attenuated the levels of intracellular ROS and the apoptosis of cardiomyocytes in a dose-dependent manner. We also demonstrated that Irisin promoted cell viability and inhibited cell apoptosis via upregulating miR-19b expression. In addition, PTEN was identified as a functional target gene of miR-19b that was responsible for its anti-apoptotic effects in cardiomyocytes. Further study demonstrated that Irisin-regulated miR-19b could reactivate the AKT/mTOR signaling pathway blocked by H₂O₂ in H9c2 cells. We demonstrated that Irisin strongly enhances cellular proliferation and preventsapoptosis of cardiomyocytes as well as attenuates the levels of intracellular ROS induced by H₂O₂. These effects might be mediated through the miR-19b/AKT/mTOR signaling pathway, which provide a new insight into the mechanism by which Irisin may have beneficial effect on myocardial remodeling.

Cardioprotective Effects of Nicorandil on Coronary Heart Disease Patients Undergoing Elective Percutaneous Coronary Intervention

Background

Nicorandil is a nicotinamide ester commonly prescribed for treatment of patients with coronary heart disease (CHD). In the present study, we aimed to explore the cardioprotective effects of nicorandil on CHD patients undergoing elective percutaneous coronary intervention (PCI).

Material/Methods

One hundred patients with CHD undergoing PCI were randomly divided into a control group (n=48) and a nicorandil group (n=52). Patients in the control group received traditional therapy, and while patients in the nicorandil group received nicorandil before PCI in addition to the traditional therapy. After PCI, all patients underwent coronary angiogram, and TIMI frame count (TFC) was calculated. Plasma levels of cardiac troponin I (cTnI), creatine kinase-MB (CK-MB), myeloperoxidase (MPO), and malondialdehyde (MDA) were determined before and at 6, 18, and 24 h after PCI. Moreover, systolic blood pressure (SBP), mean blood pressure (DBP), heart rate (HR), and left ventricular ejection fractions (LVEF) were recorded before and 3 months after PCI.

Results

There was a significant difference in the rate of no-reflow (P=0.036) between the 2 groups. The blood frames and levels of cTnI, CK-MB, MPO, and MDA in the nicorandil group were significantly decreased compared to the control group (all P<0.05). Moreover, administration of nicorandil markedly decreased SBP, MBP, and HR, but obviously increased LVEF at 3 months after PCI (P<0.05 or P<0.01).

Conclusions

Nicorandil exerts cardioprotective effects on CHD patients undergoing elective PCI by decreasing PCI-related myocardial injury and rate of no-reflow and improvement of LVEF.

A Long-Term and Slow-Releasing Hydrogen Sulfide Donor Protects against Myocardial Ischemia/Reperfusion Injury

Hydrogen sulfide (H2S) has been recognized as an important gasotransmitter exerting various physiological effects, especially in the cardiovascular system. Herein we investigated the cardioprotective effects of a novel long-term and slow-releasing H2S donor, DATS-MSN, using in vivo myocardial ischemia/reperfusion (I/R) models and in vitro hypoxia/reoxygenation cardiomyocyte models. Unlike the instant-releasing pattern of sodium hydrosulphide (NaHS), the release of H2S from DATS-MSN was quite slow and continuous both in the cell culture medium and in rat plasma (elevated H2S concentrations during 24 h and 72 h reperfusion). Correspondingly, DATS-MSN demonstrated superior cardioprotective effects over NaHS in I/R models, which were associated with greater survival rates, reduced CK-MB and troponin I levels, decreased cardiomyocyte apoptosis index, increased antioxidant enzyme activities, inhibited myocardial inflammation, greater reduction in the infarct area and preserved cardiac ejection fraction. Some of these effects of DATS-MSN were also found to be superior to classic slow-releasing H2S donor, GYY4137. In in vitro experiments, cardiomyocytes injury was also found to be relived with the use of DATS-MSN compared to NaHS after the hypoxia/reoxygenation processes. The present work provides a novel long-term and slow-releasing H2S donor and an insight into how the release patterns of H2S donors affect its physiological functionality.

Exogenous and Endogenous Hydrogen Sulfide Protects Gastric Mucosa against the Formation and Time-Dependent Development of Ischemia/Reperfusion-Induced Acute Lesions Progressing into Deeper Ulcerations

Hydrogen sulfide (H₂S) is an endogenous mediator, synthesized from l-cysteine by cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS) or 3-mercaptopyruvate sulfurtransferase (3-MST). The mechanism(s) involved in H₂S-gastroprotection against ischemia/reperfusion (I/R) lesions and their time-dependent progression into deeper gastric ulcerations have been little studied. We determined the effect of l-cysteine, H₂S-releasing NaHS or slow H₂S releasing compound GYY4137 on gastric blood flow (GBF) and gastric lesions induced by 30 min of I followed by 3, 6, 24 and 48 h of R. Role of endogenous prostaglandins (PGs), afferent sensory nerves releasing calcitonin gene-related peptide (CGRP), the gastric expression of hypoxia inducible factor (HIF)-1α and anti-oxidative enzymes were examined. Rats with or without capsaicin deactivation of sensory nerves were pretreated i.g. with vehicle, NaHS (18–180 μmol/kg) GYY4137 (90 μmol/kg) or l-cysteine (0.8–80 μmol/kg) alone or in combination with (1) indomethacin (14 μmol/kg i.p.), SC-560 (14 μmol/kg), celecoxib (26 μmol/kg); (2) capsazepine (13 μmol/kg i.p.); and (3) CGRP (2.5 nmol/kg i.p.). The area of I/R-induced gastric lesions and GBF were measured by planimetry and H₂-gas clearance, respectively. Expression of mRNA for CSE, CBS, 3-MST, HIF-1α, glutathione peroxidase (GPx)-1, superoxide dismutase (SOD)-2 and sulfide production in gastric mucosa compromised by I/R were determined by real-time PCR and methylene blue method, respectively. NaHS and l-cysteine dose-dependently attenuated I/R-induced lesions while increasing the GBF, similarly to GYY4137 (90 μmol/kg). Capsaicin denervation and capsazepine but not COX-1 and COX-2 inhibitors reduced NaHS- and l-cysteine-induced protection and hyperemia. NaHS increased mRNA expression for SOD-2 and GPx-1 but not that for HIF-1α. NaHS which increased gastric mucosal sulfide release, prevented further progression of acute I/R injury into deeper gastric ulcers at 6, 24 and 48 h of R. We conclude that H₂S-induced gastroprotection against I/R-injury is due to increase in gastric microcirculation, anti-oxidative properties and afferent sensory nerves activity but independent on endogenous prostaglandins.

Broad-Range Antiviral Activity of Hydrogen Sulfide Against Highly Pathogenic RNA Viruses

Hydrogen sulfide is an important endogenous mediator that has been the focus of intense investigation in the past few years, leading to the discovery of its role in vasoactive, cytoprotective and anti-inflammatory responses. Recently, we made a critical observation that H₂S also has a protective role in paramyxovirus infection by modulating inflammatory responses and viral replication. In this study we tested the antiviral and anti-inflammatory activity of the H₂S slow-releasing donor GYY4137 on enveloped RNA viruses from Ortho-, Filo-, Flavi- and Bunyavirus families, for which there is no FDA-approved vaccine or therapeutic available, with the exception of influenza. We found that GYY4137 significantly reduced replication of all tested viruses. In a model of influenza infection, GYY4137 treatment was associated with decreased expression of viral proteins and mRNA, suggesting inhibition of an early step of replication. The antiviral activity coincided with the decrease of viral-induced pro-inflammatory mediators and viral-induced nuclear translocation of transcription factors from Nuclear Factor (NF)-kB and Interferon Regulatory Factor families. In conclusion, increasing cellular H₂S is associated with significant antiviral activity against a broad range of emerging enveloped RNA viruses, and should be further explored as potential therapeutic approach in relevant preclinical models of viral infections.

The Role of Hydrogen Sulfide in Renal System

Hydrogen sulfide has gained recognition as the third gaseous signaling molecule after nitric oxide and carbon monoxide. This review surveys the emerging role of H2S in mammalian renal system, with emphasis on both renal physiology and diseases. H2S is produced redundantly by four pathways in kidney, indicating the abundance of this gaseous molecule in the organ. In physiological conditions, H2S was found to regulate the excretory function of the kidney possibly by the inhibitory effect on sodium transporters on renal tubular cells. Likewise, it also influences the release of renin from juxtaglomerular cells and thereby modulates blood pressure. A possible role of H2S as an oxygen sensor has also been discussed, especially at renal medulla. Alternation of H2S level has been implicated in various pathological conditions such as renal ischemia/reperfusion, obstructive nephropathy, diabetic nephropathy, and hypertensive nephropathy. Moreover, H2S donors exhibit broad beneficial effects in renal diseases although a few conflicts need to be resolved. Further research reveals that multiple mechanisms are underlying the protective effects of H2S, including anti-inflammation, anti-oxidation, and anti-apoptosis. In the review, several research directions are also proposed including the role of mitochondrial H2S in renal diseases, H2S delivery to kidney by targeting D-amino acid oxidase/3-mercaptopyruvate sulfurtransferase (DAO/3-MST) pathway, effect of drug-like H2S donors in kidney diseases and understanding the molecular mechanism of H2S. The completion of the studies in these directions will not only improves our understanding of renal H2S functions but may also be critical to translate H2S to be a new therapy for renal diseases.

An integrative view of cisplatin-induced renal and cardiac toxicities: Molecular mechanisms, current treatment challenges and potential protective measures

Cisplatin is currently one of the most widely-used chemotherapeutic agents against various malignancies. Its clinical application is limited, however, by inherent renal and cardiac toxicities and other side effects, of which the underlying mechanisms are only partly understood. Experimental studies show cisplatin generates reactive oxygen species, which impair the cell's antioxidant defense system, causing oxidative stress and potentiating injury, thereby culminating in kidney and heart failure. Understanding the molecular mechanisms of cisplatin-induced renal and cardiac toxicities may allow clinicians to prevent or treat this problem better and may also provide a model for investigating drug-induced organ toxicity in general. This review discusses some of the major molecular mechanisms of cisplatin-induced renal and cardiac toxicities including disruption of ionic homeostasis and energy status of the cell leading to cell injury and cell death. We highlight clinical manifestations of both toxicities as well as (novel)biomarkers such as kidney injury molecule-1 (KIM-1), tissue inhibitor of metalloproteinase-1 (TIMP-1) and N-terminal pro-B-type natriuretic peptide (NT-proBNP). We also present some current treatment challenges and propose potential protective strategies including combination therapy with novel pharmacological compounds that might mitigate or prevent these toxicities, which include the use of hydrogen sulfide.

Systems Medicine as an Emerging Tool for Cardiovascular Genetics

Cardiovascular disease (CVD) is a major contributor to morbidity and mortality worldwide. However, the pathogenesis of CVD is complex and remains elusive. Within the last years, systems medicine has emerged as a novel tool to study the complex genetic, molecular, and physiological interactions leading to diseases. In this review, we provide an overview about the current approaches for systems medicine in CVD. They include bioinformatical and experimental tools such as cell and animal models, omics technologies, network, and pathway analyses. Additionally, we discuss challenges and current literature examples where systems medicine has been successfully applied for the study of CVD.

Cardioprotection provided by Echinatin against ischemia/reperfusion in isolated rat hearts

Background

This study evaluated the protective effect of Echinatin against myocardial ischemia/reperfusion (I/R) injury in rats.

Methods

The effect of Echinatin on cardiac function in rats subjected to I/R was demonstrated through improved Langendorff retrograde perfusion technology. Adult Sprague–Dawley rats were randomly divided into five groups, and myocardial infarct size was macroscopically estimated through 2,3,5-triphenyltetrazolium chloride staining. The coronary effluent was analyzed for the release of lactate dehydrogenase (LDH) and creatine kinase (CK) to assess the degree of cardiac injury. The concentrations of malondialdehyde (MDA), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were determined along with superoxide dismutase (SOD) activity using ELISA. Finally, cardiomyocyte apoptosis analysis was conducted with POD, an in situ cell death detection kit.

Results

Echinatin (0.5 and 2.5 μg/mL) pretreatment enhanced the maximum up/down rate of the left ventricular pressure (±dp/dtmax), improved the heart rate, increased the left ventricular developed pressure (LVDP), enhanced the coronary flow, and reduced the CK and LDH levels in the coronary flow of the treated group compared with the I/R group. Echinatin limited the contents of CK and LDH, improved the LVDP, reduced the contents of MDA, IL-6, and TNF-α, and increased the SOD activity. The infarct size and cell apoptosis in the hearts of the rats in the Echinatin-treated group were smaller and lower, respectively, than those in the hearts of the rats in the I/R control group.

Conclusion

Echinatin exerts a protective effect against I/R-induced myocardial injury on hearts. This effect may be attributed to the antioxidant and anti-inflammatory activities of this compound.

Hydrogen Sulfide in Physiology and Diseases of the Digestive Tract

Hydrogen sulfide (H₂S) is a Janus-faced molecule. On one hand, several toxic functions have been attributed to H₂S and exposure to high levels of this gas is extremely hazardous to health. On the other hand, H₂S delivery based clinical therapies are being developed to combat inflammation, visceral pain, oxidative stress related tissue injury, thrombosis and cancer. Since its discovery, H₂S has been found to have pleiotropic effects on physiology and health. H₂S is a gasotransmitter that exerts its effect on different systems, such as gastrointestinal, neuronal, cardiovascular, respiratory, renal, and hepatic systems. In the gastrointestinal tract, in addition to H₂S production by mammalian cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), H₂S is also generated by the metabolic activity of resident gut microbes, mainly by colonic Sulfate-Reducing Bacteria (SRB) via a dissimilatory sulfate reduction (DSR) pathway. In the gut, H₂S regulates functions such as inflammation, ischemia/ reperfusion injury and motility. H₂S derived from gut microbes has been found to be associated with gastrointestinal disorders such as ulcerative colitis, Crohn’s disease and irritable bowel syndrome. This underscores the importance of gut microbes and their production of H₂S on host physiology and pathophysiology.