Cardioprotection induced by hydrogen sulfide preconditioning involves activation of ERK and PI3K/Akt pathways

Cardioprotective Effects of Hydrogen Sulfide and Its Potential Therapeutic Implications in the Amelioration of Duchenne Muscular Dystrophy Cardiomyopathy

Hydrogen sulfide (H2S) belongs to the family of gasotransmitters and can modulate a myriad of biological signaling pathways. Among others, its cardioprotective effects, through antioxidant, anti-inflammatory, anti-fibrotic, and proangiogenic activities, are well-documented in experimental studies. Cardiorespiratory failure, predominantly cardiomyopathy, is a life-threatening complication that is the number one cause of death in patients with Duchenne muscular dystrophy (DMD). Although recent data suggest the role of H2S in ameliorating muscle wasting in murine and Caenorhabditis elegans models of DMD, possible cardioprotective effects have not yet been addressed. In this review, we summarize the current understanding of the role of H2S in animal models of cardiac dysfunctions and cardiac cells. We highlight that DMD may be amenable to H2S supplementation, and we suggest H2S as a possible factor regulating DMD-associated cardiomyopathy.

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 attenuates uranium-induced kidney cells pyroptosis via upregulation of PI3K/AKT/mTOR signaling

We have identified that hydrogen sulfide (H₂ S), a gaseous mediator, plays a crucial role in antioxidative, anti-inflammatory, and cytoprotective effects on uranium (U)-triggered rat nephrotoxicity. Pyroptosis is a special mode of inflammation and programmed cell death involved in the activation of inflammasome and Caspase-1 and the release of inflammatory cytokines. This study aims to confirm whether H₂ S can alleviate U-induced rat NRK-52^E cell pyroptosis and to investigate the H₂ S underlying regulatory mechanism. Our results indicate that pretreatment with NaHS (an H₂ S donor) significantly inhibited U-increased reactive oxygen species level, NLRP3, apoptosis-related speck-like protein consisting of a caspase recruitment domain (ASC), and cleaved Caspase-1 proteins expression, gasdermin D messenger RNA (GSDMD mRNA) expression, interleukin (IL)-1β and IL-18 contents, lactate dehydrogenase leakage, and numbers of double-positive dying kidney cells. NaHS application evidently augmented phosphorylated PI3K, AKT, and mTOR expression as well as ratios of their respective phosphorylation to the corresponding total proteins which were downregulated by U treatment. But, LY294002 (a PI3K inhibitor) administration effectively abrogated the consequences of NaHS on the levels of p-PI3K, cleaved Caspase-1, ASC and NLRP3 proteins, GSDMD mRNA expression, and (IL)-1β and IL-18 contents. Simultaneously, LY294002 significantly reversed the effects of NaHS on U-induced pyroptosis rate and cytotoxicity. Taken together, these results indicate that H₂ S ameliorated U-triggered NRK-52^E cells pyroptosis via upregulation of PI3K/AKT/mTOR pathway, suggesting a novel role for H₂ S in the management of nephrotoxicity caused by U exposure.

Emerging roles of cystathionine β-synthase in various forms of cancer

The expression of the reverse transsulfuration enzyme cystathionine-β-synthase (CBS) is markedly increased in many forms of cancer, including colorectal, ovarian, lung, breast and kidney, while in other cancers (liver cancer and glioma) it becomes downregulated. According to the clinical database data in high-CBS-expressor cancers (e.g. colon or ovarian cancer), high CBS expression typically predicts lower survival, while in the low-CBS-expressor cancers (e.g. liver cancer), low CBS expression is associated with lower survival. In the high-CBS expressing tumor cells, CBS, and its product hydrogen sulfide (H₂S) serves as a bioenergetic, proliferative, cytoprotective and stemness factor; it also supports angiogenesis and epithelial-to-mesenchymal transition in the cancer microenvironment. The current article reviews the various tumor-cell-supporting roles of the CBS/H₂S axis in high-CBS expressor cancers and overviews the anticancer effects of CBS silencing and pharmacological CBS inhibition in various cancer models in vitro and in vivo; it also outlines potential approaches for biomarker identification, to support future targeted cancer therapies based on pharmacological CBS inhibition.

Excessive hydrogen sulfide causes lung and brain tissue damage by promoting PARP1/Bax and C9 and inhibiting LAMB1

Excessive hydrogen sulfide (H₂S) causes serious damage to human organs and tissues. In this study, we aimed to explore the role and underlying mechanism of excessive H₂S in brain and lung tissues. A H₂S concentration of 100-800 pm promotes apoptosis and inflammation of brain and lung cells in ICR mice. Mechanistically, a H₂S concentration of 100-800 pm upregulates PARP1 and Bax expression in a dose-dependent manner in vivo and in vitro, and functional gain-and-loss experiments verified that an excessive amount of H₂S plays a pro-apoptotic role in HT22 and MML1 cells via regulation of PARP1 and Bax in vitro. By combining animal and cell experiments, we clarified that excess H₂S promotes the inflammatory response of mouse brain and lung cells by promoting the expression of C9. In addition, the downregulation of LAMB1 by an excessive H₂S concentration was confirmed using mass spectrometry and western blotting in vivo and in vitro. Combined with in vitro experiments, we found that an excessive H₂S concentration promotes the expression of STAT1 and EGFR in HT22 and MML1 cells by inhibiting the expression of LAMB1. In summary, 100-800 pm H₂S causes the brain and lung tissue damage in ICR mice, the underlying mechanisms include H₂S induced apoptosis and inflammation of mouse brain and lung cells by upregulation of PARP1/Bax and C9, respectively, and H₂S might induce fibrosis of mouse brain and lung cells by downregulation of LAMB1.

Hydrogen Sulfide: An Emerging Precision Strategy for Gas Therapy

Advances in nanotechnology have enabled the rapid development of stimuli-responsive therapeutic nanomaterials for precision gas therapy. Hydrogen sulfide (H₂ S) is a significant gaseous signaling molecule with intrinsic biochemical properties, which exerts its various physiological effects under both normal and pathological conditions. Various nanomaterials with H₂ S-responsive properties, as new-generation therapeutic agents, are explored to guide therapeutic behaviors in biological milieu. The cross disciplinary of H₂ S is an emerging scientific hotspot that studies the chemical properties, biological mechanisms, and therapeutic effects of H₂ S. This review summarizes the state-of-art research on H₂ S-related nanomedicines. In particular, recent advances in H₂ S therapeutics for cancer, such as H₂ S-mediated gas therapy and H₂ S-related synergistic therapies (combined with chemotherapy, photodynamic therapy, photothermal therapy, and chemodynamic therapy) are highlighted. Versatile imaging techniques for real-time monitoring H₂ S during biological diagnosis are reviewed. Finally, the biosafety issues, current challenges, and potential possibilities in the evolution of H₂ S-based therapy that facilitate clinical translation to patients are discussed.

An evolutionary perspective on the interplays between hydrogen sulfide and oxygen in cellular functions

The physiological effects of the endogenously generated hydrogen sulfide (H2S) have been extensively studied in recent years. This review summarized the role of H2S in the origin of life and H2S metabolism in organisms from bacteria to vertebrates, examined the relationship between H2S and oxygen from an evolutionary perspective and emphasized the oxygen-dependent manner of H2S signaling in various physiological and pathological processes. H2S and oxygen are inextricably linked in various cellular functions. H2S is involved in aerobic respiration and stimulates oxidative phosphorylation and ATP production within the cell. Besides, H2S has protective effects on ischemia and reperfusion injury in several organs by acting as an oxygen sensor. Also, emerging evidence suggests the role of H2S is in an oxygen-dependent manner. All these findings indicate the subtle relationship between H2S and oxygen and further explain why H2S, a toxic molecule thriving in an anoxia environment several billion years ago, still affects homeostasis today despite the very low content in the body.

CoenzymeQ in cellular redox regulation and clinical heart failure

Coenzyme Q (CoQ) is ubiquitously embedded in lipid bilayers of various cellular organelles. As a redox cycler, CoQ shuttles electrons between mitochondrial complexes and extramitochondrial reductases and oxidases. In this way, CoQ is crucial for maintaining the mitochondrial function, ATP synthesis, and redox homeostasis. Cardiomyocytes have a high metabolic rate and rely heavily on mitochondria to provide energy. CoQ levels, in both plasma and the heart, correlate with heart failure in patients, indicating that CoQ is critical for cardiac function. Moreover, CoQ supplementation in clinics showed promising results for treating heart failure. This review provides a comprehensive view of CoQ metabolism and its interaction with redox enzymes and reactive species. We summarize the clinical trials and applications of CoQ in heart failure and discuss the caveats and future directions to improve CoQ therapeutics.

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.

Role of Hydrogen Sulfide in Myocardial Ischemia-Reperfusion Injury

ABSTRACT

Hydrogen sulfide (H2S), generally known as a new gas signal molecule after nitric oxide and carbon monoxide, has been found as an important endogenous gasotransmitter in the last few decades, and it plays a significant role in the cardiovascular system both pathologically and physiologically. In recent years, there is growing evidence that H2S provides myocardial protection against myocardial ischemia-reperfusion injury (MIRI), which resulted in an ongoing focus on the possible mechanisms of action accounting for the H2S cardioprotective effect. At present, lots of mechanisms of action have been verified through in vitro and in vivo models of I/R injury, such as S-sulfhydrated modification, antiapoptosis, effects on microRNA, bidirectional effect on autophagy, antioxidant stress, or interaction with NO and CO. With advances in understanding of the molecular pathogenesis of MIRI and pharmacology studies, the design, the development, and the pharmacological characterization of H2S donor drugs have made great important progress. This review summarizes the latest research progress on the role of H2S in MIRI, systematically explains the molecular mechanism of H2S affecting MIRI, and provides a new idea for the formulation of a myocardial protection strategy in the future.

Beneficial effect of sodium thiosulfate extends beyond myocardial tissue in isoproterenol model of infarction: Implication for nootropic effects

One of the common negative impacts in the management of acute myocardial infarction is cognitive decline. Using the rat model of isoproterenol (ISO)-induced myocardial infarction, we assessed the cardioprotective effect of sodium thiosulfate (STS) and its influence on cognition. STS treatment reduced the cardiac infarct size by 75%, injury markers (lactate dehydrogenase: 60%, creatine kinase-muscle/brain: 44%) release in the blood, maintain the heart rate within a normal range (365 ± 10 bpm) and minimize postinfarction hypertrophic changes in comparison with the ISO group. At the cellular level, the heart from these rats had reduced reactive oxygen species (ROS) (25%), caspase-9 (60%), and improved mitochondrial function (restored electron transport chain function and copy number) compared to ISO hearts. The brain of STS-treated rats also showed a reduction in ROS (45%), caspase-9 (37%), and improved mitochondrial function relative to the brain of the ISO group, particularly limited to the striatum region, and these rats showed improved cognitive ability. Predominantly, the STS treatment reduced the reference memory defects observed in comparison to rats challenged by ISO. Furthermore, elevated circulating mitochondrial DNA and ATP were found in ISO-challenged rats, which indicate the cardiac mitochondria linked damage-associated patterns were restored to the sham level when pretreated with STS. We found increased H₂ S, a well-known metabolite of STS with a neuroprotective role in the brain after STS administration, hinting at a possible secondary defense mechanism. In conclusion, the STS mediated cardioprotection and its nootropic effects are primarily mediated via the improvement of mitochondrial function and reduction of oxidative stress.

Sodium thiosulfate prevents doxorubicin-induced DNA damage and apoptosis in cardiomyocytes in mice

AIM

Doxorubicin (DOX) induces dose-dependent cardiotoxicity due to reactive oxygen species (ROS)-mediated oxidative stress and subsequent apoptosis of cardiomyocytes. We aimed to assess whether sodium thiosulfate (STS), which has antioxidant and antiapoptotic properties, exerts cardioprotective effects on DOX-induced cardiomyopathy.

MAIN METHODS

Male C57BL/6N mice were divided into four groups, control, DOX, STS, and DOX + STS, and administered DOX (20 or 30 mg/kg) or normal saline intraperitoneally, followed by an injection of STS (2 g/kg) or normal saline 4 h later.

KEY FINDINGS

The DOX group showed a poorer 6-day survival and decreased cardiac function than the DOX + STS group. The DOX group showed a marked increase in the plasma creatine kinase isoenzyme myocardial band (CK-MB) and lactate dehydrogenase (LDH) levels 10 h after DOX injection, while the DOX + STS group showed suppression of DOX-induced elevation of CK-MB and LDH levels. The DOX group showed increased 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the heart, whereas the DOX + STS group showed increased catalase and superoxide dismutase (SOD) activities and decreased 8-OHdG levels in the heart compared with DOX group, suggesting that STS reduces DOX-induced DNA damage by improving antioxidant enzymes activities in cardiomyocytes. Additionally, the DOX + STS group showed attenuation of cleaved caspase-3 and DNA fragmentation in cardiomyocytes compared with the DOX group, suggesting that STS suppresses DOX-induced apoptosis in cardiomyocytes.

SIGNIFICANCE

STS exerts cardioprotective effects against DOX-induced cardiac dysfunction partly by improving antioxidant defense and suppressing apoptosis, indicating the therapeutic potential of STS against DOX-induced cardiomyopathy.

Hydrogen Sulfide Treatment Improves Post-Infarct Remodeling and Long-Term Cardiac Function in CSE Knockout and Wild-Type Mice

Hydrogen sulfide (H2S) is recognized as an endogenous gaseous signaling molecule generated by cystathionine γ-lyase (CSE) in cardiovascular tissues. H2S up-regulation has been shown to reduce ischemic injury, and H2S donors are cardioprotective in rodent models when administered concurrent with myocardial ischemia. We evaluated the potential utility of H2S therapy in ameliorating cardiac remodeling with administration delayed until 2 h post-infarction in mice with or without cystathionine γ-lyase gene deletion (CSE-/-). The slow-release H2S donor, GYY4137, was administered from 2 h after surgery and daily for 28 days following myocardial infarction (MI) induced by coronary artery ligation, comparing responses in CSE-/- with wild-type (WT) mice (n = 5-10/group/genotype). Measures of cardiac function and expression of key genes associated with cardiac hypertrophy, fibrosis, and apoptosis were documented in atria, ventricle, and kidney tissues. Post-MI GYY4137 administration reduced infarct area and restored cardiac function, accompanied by reduction of the elevated ventricular expression of genes mediating cardiac remodeling to near-normal levels. Few differences between WT and CSE-/- mice were observed, except CSE-/- mice had higher blood pressures, and higher atrial Mir21a expression across all treatment groups. These findings suggest endogenous CSE gene deletion does not substantially exacerbate the long-term response to MI. Moreover, the H2S donor GYY4137 administered after onset of MI preserves cardiac function and protects against adverse cardiac remodeling in both WT and CSE-deficient mice.

Protective mechanisms of hydrogen sulfide in myocardial ischemia

Hydrogen sulfide (H₂ S), which has been identified as the third gaseous signaling molecule after nitric oxide (NO) and carbon monoxide (CO), plays an important role in maintaining homeostasis in the cardiovascular system. Endogenous H₂ S is produced mainly by three endogenous enzymes: cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfur transferase. Numerous studies have shown that H₂ S has a significant protective role in myocardial ischemia. The mechanisms by which H₂ S affords cardioprotection include the antifibrotic and antiapoptotic effects, regulation of ion channels, protection of mitochondria, reduction of oxidative stress and inflammatory response, regulation of microRNA expression, and promotion of angiogenesis. Amplification of NO- and CO-mediated signaling through crosstalk between H₂ S, NO, and CO may also contribute to the cardioprotective effect. Exogenous H₂ S donors are expected to become effective drugs for the treatment of cardiovascular diseases. This review article focuses on the protective mechanisms and potential therapeutic applications of H₂ S in myocardial ischemia.

Hydrogen Sulfide and Endoplasmic Reticulum Stress: A Potential Therapeutic Target for Central Nervous System Degeneration Diseases

There are three members of the endogenous gas transmitter family. The first two are nitric oxide and carbon monoxide, and the third newly added member is hydrogen sulfide (H₂S). They all have similar functions: relaxing blood vessels, smoothing muscles, and getting involved in the regulation of neuronal excitation, learning, and memory. The cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfur transferase acts together with cysteine aminotransferase (3-MST/CAT), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfur transferase with D-amino acid oxidase (3-MST/DAO) pathways are involved in the enzymatic production of H₂S. More and more researches focus on the role of H₂S in the central nervous system (CNS), and H₂S plays a significant function in neuroprotection processes, regulating the function of the nervous system as a signaling molecule in the CNS. Endoplasmic reticulum stress (ERS) and protein misfolding in its mechanism are related to neurodegenerative diseases. H₂S exhibits a wide variety of cytoprotective and physiological functions in the CNS degenerative diseases by regulating ERS. This review summarized on the neuroprotective effect of H₂S for ERS played in several CNS diseases including Alzheimer’s disease, Parkinson’s disease, and depression disorder, and discussed the corresponding possible signaling pathways or mechanisms as well.

Cardioprotective effect of electroacupuncture in cardiopulmonary bypass through apelin/APJ signaling

Aim Acupuncture, particularly electroacupuncture (EA), can improve the clinical outcomes of cardiopulmonary bypass (CPB) patients; however, the mechanisms remain unclear. This study aimed to examine the effects of EA pre-treatment on myocardial injury after CPB and investigate its potential mechanisms.

MAIN METHODS

Male Sprague-Dawley rats were subjected to CPB and divided into Control (sham-operated), CPB, and EA (CPB + EA) groups. In the EA group, rats were treated with EA at the "PC6" acupoint for 30 min before being subjected to CPB. At 0.5, 1, and 2 h after CPB, the expression levels of plasma cardiac troponin I (cTnI) and lactate dehydrogenase (LDH), and myeloperoxidase (MPO) activity, TNFα, IL-1β, reduced glutathione (GSH), oxidized glutathione (GSSH), and the ratio of GSH/GSSH in the myocardial tissue were measured. Apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining. The expression of cleaved caspase-3 was detected by immunofluorescence. The expression of apelin, APJ, AKT, p-Akt, ERK1/2, and p-ERK1/2 was determined using western blotting.

KEY FINDINGS

Decreased myocardial injury marker levels, myocardial apoptosis, oxidative stress, and the inflammatory response were found in the EA group compared with the CPB group. The expression levels of apelin, APJ, and p-Akt/AKT were increased in the EA group, and the p-ERK1/2/ERK1/2 level was decreased.

SIGNIFICANCE

This study showed that EA pre-treatment can protect the heart from damage following CPB, which might be mainly mediated by restoring the apelin/APJ signaling pathway.

Release of endogenous hydrogen sulfide in enteric nerve cells suppresses intestinal motility during severe acute pancreatitis

Previous studies have shown that during severe acute pancreatitis (SAP) attacks, hydrogen sulfide (H2S) is released in the colon. However, the roles played by H2S in regulating enteric nerves remain unclear. In this study, we examined the association between SAP-induced H2S release and loss of intestinal motility, and also explored the relevant mechanism in enteric nerve cells. A rat SAP model was constructed and enteric nerve cells were prepared. Intestinal mobility was evaluated by measuring the number of bowel movements at indicated time points and by performing intestinal propulsion tests. The production of inflammatory cytokines during a SAP attack was quantified by ELISA, and the levels of cystathionine-γ-lyase (CSE) and cystathionine-β-synthase (CBS) were examined by immunohistochemistry and western blot analysis. In vivo studies showed that PI3K/Akt/Sp1 signaling in enteric nerve cells was blocked, confirming the mechanism of endogenous H2S formation by western blot analysis and immunofluorescence. Our results also showed that rats with SAP symptoms had reduced intestinal motility. Furthermore, PI3K/Akt/Sp1 signaling was triggered and CSE expression was up-regulated, and these changes were associated with H2S formation in the colon. In addition, propargylglycine reduced the levels of inflammatory cytokines and suppressed the release of H2S. Enteric nerve cells that were incubated with LY294002 and transfected with a Sp1-knockdown vector displayed decreased levels of CSE production, which led to a decrease in H2S production. These results suggest that SAP symptoms suppressed the intestinal motility of rats via the release of H2S in enteric nerve cells, which was dependent on the inflammation-induced PI3K/Akt/Sp1 signaling pathway.

Role of Hydrogen Sulfide in Chronic Diseases

In the past, hydrogen sulfide (H₂S) was considered as a poisonous gas or waste of the body. Later, researchers found that H₂S-producing enzymes exist in mammals. Moreover, their findings indicated that endogenous H₂S was associated with the occurrence of many diseases. Therefore, endogenous H₂S is able to participate in the regulation of physiological and pathological functions of the body as a gas signaling molecule. In this review, we summarize the regulation mechanism of endogenous H₂S on the body, such as proliferation, apoptosis, migration, angiogenesis, as well as vasodilation/vasoconstriction. Furthermore, we also analyze the relationship between H₂S and some chronic diseases, including hypoxic pulmonary hypertension, myocardial infarction, ischemic perfusion kidney injury, diabetes, and chronic intestinal diseases. Finally, we discuss dietary restriction and drugs that target for H₂S. Hence, H₂S is expected to become a potential target for treatment of these chronic diseases.

The protective effects of hydrogen sulfide on the myocardial ischemia via regulating Bmal1

BACKGROUND

To investigate the effect of hydrogen peroxide (H₂S) on myocardial clock gene Bmal1 in ischemic cardiomyocytes.

MATERIALS & METHODS

Quantitative PCR (qPCR) was used to detect the expression of Bmal1 at the mRNA level in H9C2 rat cardiomyocytes. The protein expressions of Bax and Bcl-2, PI3K/Akt, caspase-3 were measured by western blotting. The levels of reactive oxygen species (ROS) were determined by ELISA.

RESULTS

The expression level of clock gene Bmal1 demonstrated a clock rhythm of periodic oscillation within 24 h. Compared with the control group, H₂S treatment maintained the rhythm of the clock gene in ischemic cardiomyocytes and increased the transcription and expression levels of Bmal1. H₂S increased cell survival by activating PI3K/Akt signaling pathway, inhibiting mitochondrial apoptosis signaling, and reducing intracellular oxidative stress. PI3K/Akt and Bmal1 were demonstrated to be involved in H₂S protection of cardiomyocyte ischemia. Knockout of Bmal1 gene affects the degree of phosphorylation of Akt and Erk proteins, and the level of ROS production, resulting in a decrease in the protective effects of H₂S.

CONCLUSION

The expression level of Bmal1 has effects on the function of cardiomyocytes such as ROS production. The potential mechanism by which H₂S regulates clock genes may be related to the effect of clock genes on protein phosphorylation levels in ischemic cardiomyocytes.

Mechanism of H2S-mediated ROCK inhibition of total flavones of Rhododendra against myocardial ischemia injury

Our previous studies have indicated that pretreatment with total flavones of Rhododendra flower (TFR) may protect against myocardial ischemic injuries in rats and mice. The cystathionine γ-lyase/hydrogen sulfide (CSE/H₂S) pathway have been associated with several cardiovascular diseases, but the effect of TFR on the Rho-associated protein kinase (ROCK) and CSE/H₂S signaling pathways remains unknown. In the present study, the protective effects of TFR as a ROCK inhibitor in a mice model of myocardial infarction induced by isoproterenol (ISO) were investigated, and the hearts from the wild type and CSE knockout (KO) mice were examined. It was identified that the CSE KO mice exhibited decreased levels of ST segment elevation following anoxia/reoxygenation damage, increased LDH and CK-MB levels, aggravated pathological damage, and increased ROCK1, ROCK2 and MLC1 protein levels. In the CSE KO mice, there were no marked changes of the above experimental results between the TFR group and the model group. These results suggested that TFR-based inhibition of the RhoA/ROCK signal pathway may be mediated by the CSE-H₂S signalling pathway and may be a novel therapeutic target for myocardial ischemia injury.

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

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

Macrophage migration inhibitory factor plays an essential role in ischemic preconditioning-mediated cardioprotection

Ischemic preconditioning (IPC) is an endogenous protection strategy against myocardial ischemia-reperfusion (I/R) injury. Macrophage migration inhibitory factor (MIF) released from the myocardium subjected to brief periods of ischemia confers cardioprotection. We hypothesized that MIF plays an essential role in IPC-induced cardioprotection. I/R was induced either ex vivo or in vivo in male wild-type (WT) and MIF knockout (MIFKO) mice with or without proceeding IPC (three cycles of 5-min ischemia and 5-min reperfusion). Indices of myocardial injury, regional inflammation and cardiac function were determined to evaluate the extent of I/R injury. Activations of the reperfusion injury salvage kinase (RISK) pathway, AMP-activated protein kinase (AMPK) and their downstream components were investigated to explore the underlying mechanisms. IPC conferred prominent protection in WT hearts evidenced by reduced infarct size (by 33-35%), myocyte apoptosis and enzymatic markers of tissue injury, ROS production, inflammatory cell infiltration and MCP1/CCR2 expression (all P<0.05). IPC also ameliorated cardiac dysfunction both ex vivo and in vivo These protective effects were abolished in MIFKO hearts. Notably, IPC mediated further activations of RISK pathway, AMPK and the membrane translocation of GLUT4 in WT hearts. Deletion of MIF blunted these changes in response to IPC, which is the likely basis for the absence of protective effects of IPC against I/R injury. In conclusion, MIF plays a critical role in IPC-mediated cardioprotection under ischemic stress by activating RISK signaling pathway and AMPK. These results provide an insight for developing a novel therapeutic strategy that target MIF to protect ischemic hearts.

Piceatannol pretreatment alleviates acute cardiac injury via regulating PI3K-Akt-eNOS signaling in H9c2 cells

Piceatannol (3,3',4,5'-trans-trihydroxystilbene) is a natural polyphenols compound that occurs hydroxylated analogue of resveratrol showing widely biological activities. Previous studies have demonstrated its functions on anti-cancer, neuroprotection and cardioprotection. However, few studies have clarified the benefits of piceatannol on cardiomyocytes except its anti-oxidative effect based on the original property of polyphenols. Here we apply H9c2 cardiomyocytes to study the cardioprotective mechanisms of piceatannol in vitro. We firstly verify its anti-peroxidation effect by using H₂O₂-induced in vitro model. Then, flow cytometry results show piceatannol reduce cellular apoptosis by enhancing Bcl-2 expressions in immunoblot analysis. Meantime, piceatannol decreases H₂O₂-induced excessive ROS and calcium overloading, and prevents mitochondrial depolarization. Most importantly, piceatannol pretreatment can regulate PI3K-Akt-eNOS signaling pathway to alleviate peroxidative injury. Immunoblot analysis of PI3K, Akt, p-Akt and eNOS shows H₂O₂ significantly reduces expressions of these proteins. Pretreatment of piceatannol evidently increases their expressions and decreases iNOS expression, implying piceatannol can upregulate PI3K-Akt-eNOS signaling to protect cardiomyocytes from peroxidative injury.

Serum Exosomes Attenuate H2O2-Induced Apoptosis in Rat H9C2 Cardiomyocytes via ERK1/2

Exosomes are small-sized vesicles that can be released from cells into the serum. Exosomes play important roles in regulating many biological processes including cell proliferation, apoptosis, cell cycle, and metabolism. However, the roles and mechanisms of plasma exosomes in the apoptosis of rat H9C2 cardiomyocytes are largely unknown. In this study, we isolated plasma exosomes as confirmed by the marker protein CD63. Using flow cytometry and western blot analysis, we found that exosomes attenuated hydrogen peroxide (H₂O₂)-induced apoptosis and improved survival of rat H9C2 cardiomyocytes. Furthermore, the anti-apoptosis effects of serum exosomes in rat H9C2 cardiomyocytes were mediated by the activation of ERK1/2 signaling pathway. These data indicated that plasma exosomes had the protective effects against cardiomyocyte apoptosis and might be a novel therapy strategy for myocardial injury.

Salvianic acid A sodium protects HUVEC cells against tert-butyl hydroperoxide induced oxidative injury via mitochondria-dependent pathway

Salvianic acid A (Danshensu) is a major water-soluble component extracted from Salvia miltiorrhiza (Danshen), which has been widely used in clinic in China for treatment of cardiovascular diseases (CVDs). This study aimed to investigate the protective effects of salvianic acid A sodium (SAAS) against tert-butyl hydroperoxide (t-BHP) induced human umbilical vein endothelial cell (HUVEC) oxidative injury and the underlying molecular mechanisms. In the antioxidant activity-assessing model, SAAS pretreatment significantly ameliorated the cell growth inhibition and apoptosis induced by t-BHP. An ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) based-metabolic profiling was developed to investigate the metabolic changes of HUVEC cells in response to t-BHP and SAAS. The results revealed that t-BHP injury upregulated 13 metabolites mainly involved in tryptophan metabolism and phenylalanine metabolism which were highly correlated with mitochondrial function and oxidative stress, and 50 μM SAAS pretreatment effectively reversed these metabolic changes. Further biomedical research indicated that SAAS pretreatment reduced the t-BHP induced increase of lactate dehydrogenase (LDH), intracellular reactive oxygen species (ROS), malondialdehyde (MDA) and mitochondrial membrane potential (MMP), and the decrease of key antioxidant enzymes through mitochondria antioxidative pathways via JAK2/STAT3 and PI3K/Akt/GSK-3β signalings. Taken together, our results suggested that SAAS may protect HUVEC cells against t-BHP induced oxidative injury via mitochondrial antioxidative defense system.

International Union of Basic and Clinical Pharmacology. CII: Pharmacological Modulation of H2S Levels: H2S Donors and H2S Biosynthesis Inhibitors

Over the last decade, hydrogen sulfide (H2S) has emerged as an important endogenous gasotransmitter in mammalian cells and tissues. Similar to the previously characterized gasotransmitters nitric oxide and carbon monoxide, H2S is produced by various enzymatic reactions and regulates a host of physiologic and pathophysiological processes in various cells and tissues. H2S levels are decreased in a number of conditions (e.g., diabetes mellitus, ischemia, and aging) and are increased in other states (e.g., inflammation, critical illness, and cancer). Over the last decades, multiple approaches have been identified for the therapeutic exploitation of H2S, either based on H2S donation or inhibition of H2S biosynthesis. H2S donation can be achieved through the inhalation of H2S gas and/or the parenteral or enteral administration of so-called fast-releasing H2S donors (salts of H2S such as NaHS and Na2S) or slow-releasing H2S donors (GYY4137 being the prototypical compound used in hundreds of studies in vitro and in vivo). Recent work also identifies various donors with regulated H2S release profiles, including oxidant-triggered donors, pH-dependent donors, esterase-activated donors, and organelle-targeted (e.g., mitochondrial) compounds. There are also approaches where existing, clinically approved drugs of various classes (e.g., nonsteroidal anti-inflammatories) are coupled with H2S-donating groups (the most advanced compound in clinical trials is ATB-346, an H2S-donating derivative of the non-steroidal anti-inflammatory compound naproxen). For pharmacological inhibition of H2S synthesis, there are now several small molecule compounds targeting each of the three H2S-producing enzymes cystathionine-β-synthase (CBS), cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase. Although many of these compounds have their limitations (potency, selectivity), these molecules, especially in combination with genetic approaches, can be instrumental for the delineation of the biologic processes involving endogenous H2S production. Moreover, some of these compounds (e.g., cell-permeable prodrugs of the CBS inhibitor aminooxyacetate, or benserazide, a potentially repurposable CBS inhibitor) may serve as starting points for future clinical translation. The present article overviews the currently known H2S donors and H2S biosynthesis inhibitors, delineates their mode of action, and offers examples for their biologic effects and potential therapeutic utility.

ATP-sensitive potassium (KATP) channel openers diazoxide and nicorandil lower intraocular pressure by activating the Erk1/2 signaling pathway

Elevated intraocular pressure is the most prevalent and only treatable risk factor for glaucoma, a degenerative disease of the optic nerve. While treatment options to slow disease progression are available, all current therapeutic and surgical treatments have unwanted side effects or limited efficacy, resulting in the need to identify new options. Previous reports from our laboratory have established a novel ocular hypotensive effect of ATP-sensitive potassium channel (KATP) openers including diazoxide (DZ) and nicorandil (NCD). In the current study, we evaluated the role of Erk1/2 signaling pathway in KATP channel opener mediated reduction of intraocular pressure (IOP). Western blot analysis of DZ and NCD treated primary normal trabecular meshwork (NTM) cells, human TM (isolated from perfusion cultures of human anterior segments) and mouse eyes showed increased phosphorylation of Erk1/2 when compared to vehicle treated controls. DZ and NCD mediated pressure reduction (p<0.02) in human anterior segments (n = 7 for DZ, n = 4 for NCD) was abrogated by U0126 (DZ + U0126: -9.7 ± 11.5%, p = 0.11; NCD + U0126: -0.1 ± 11.5%, p = 1.0). In contrast, U0126 had no effect on latanoprostfree acid-induced pressure reduction (-52.5 ± 6.8%, n = 4, p = 0.001). In mice, DZ and NCD reduced IOP (DZ, 14.9 ± 3.8%, NCD, 16.9 ± 2.5%, n = 10, p<0.001), but the pressure reduction was inhibited by U0126 (DZ + U0126, 0.7 ± 3.0%; NCD + U0126, 0.9 ± 2.2%, n = 10, p>0.1). Histologic evaluation of transmission electron micrographs from DZ + U0126 and NCD + U0126 treated eyes revealed no observable morphological changes in the ultrastructure of the conventional outflow pathway. Taken together, the results indicate that the Erk1/2 pathway is necessary for IOP reduction by KATP channel openers DZ and NCD.

Protective Actions of H2S in Acute Myocardial Infarction and Heart Failure

Hydrogen sulfide (H2S) was identified as the third gasotransmitter in 1996 following the discoveries of the biological importance of nitric oxide and carbon monoxide. Although H2S has long been considered a highly toxic gas, the discovery of its presence and enzymatic production in mammalian tissues supports a critical role for this physiological signaling molecule. H2S is synthesized endogenously by three enzymes: cystathionine β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase. H2S plays a pivotal role in the regulation of cardiovascular function as H2S has been shown to modulate: vasodilation, angiogenesis, inflammation, oxidative stress, and apoptosis. Perturbation of endogenous production of H2S has been associated with many pathological conditions of the cardiovascular system such as diabetes, heart failure, and hypertension. As such, modulation of the endogenous H2S signaling pathway or administration of exogenous H2S has been shown to be cytoprotective. This review article will provide a summary of the current body of evidence on the role of H2S signaling in the setting of myocardial ischemia and heart failure. © 2017 American Physiological Society. Compr Physiol 7:583-602, 2017.

Endogenous hydrogen sulfide contributes to uterine quiescence during pregnancy

Recent evidence suggests that uterine activation for labor is associated with inflammation within uterine tissues. Hydrogen sulfide (H₂S) plays a critical role in inflammatory responses in various tissues. Our previous study has shown that human myometrium produces H₂S via its generating enzymes cystathionine-γ-lyase (CSE) and cystathionine-β-synthetase (CBS) during pregnancy. We therefore explored whether H₂S plays a role in the maintenance of uterine quiescence during pregnancy. Human myometrial biopsies were obtained from pregnant women at term. Uterine smooth muscle cells (UMSCs) isolated from myometrial tissues were treated with various reagents including H₂S. The protein expression of CSE, CBS and contraction-associated proteins (CAPs) including connexin 43, oxytocin receptor and prostaglandin F_2α receptor determined by Western blot. The levels of cytokines were measured by ELISA. The results showed that CSE and CBS expression inversely correlated to the levels of CAPs and activated NF-κB in pregnant myometrial tissues. H₂S inhibited the expression of CAPs, NF-κB activation and the production of interleukin (IL)-1β, IL-6 and tumor necrosis factor α (TNFα) in cultured USMCs. IL-1β treatment reversed H₂S inhibition of CAPs. Knockdown of CSE and CBS prevented H₂S suppression of inflammation. H₂S modulation of inflammation is through K_ATP channels and phosphoinositide 3-kinase (PI3K) and extracellular signal-regulated kinase (ERK) signaling pathways. H₂S activation of PI3K and ERK signaling is dependent on K_ATP channels. Our data suggest that H₂S suppresses the expression of CAPs via inhibition of inflammation in myometrium. Endogenous H₂S is one of the key factors in maintenance of uterine quiescence during pregnancy.

Hydrogen sulfide protects against endoplasmic reticulum stress and mitochondrial injury in nucleus pulposus cells and ameliorates intervertebral disc degeneration

It has been suggested that excessive apoptosis in intervertebral disc cells induced by inflammatory cytokines, such as interleukin (IL)-1β, is related to the process of intervertebral disc degeneration (IVDD). Hydrogen sulfide (H₂S), a gaseous signaling molecule, has drawn attention for its anti-apoptosis role in various pathophysiological processes in degenerative diseases. To date, there has been no investigation of the correlation of H₂S production and IVDD or of the effects of H₂S on IL-1β-induced apoptosis in nucleus pulposus (NP) cells. Here, we found that the expression levels of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), two key enzymes in the generation of H₂S, were significantly decreased in human degenerate NP tissues as well as in IL-1β-treated NP cells. NaHS (H₂S donor) administration showed a protective effect by inhibiting the endoplasmic reticulum (ER) stress response and mitochondrial dysfunction induced by IL-1β stimulation in vitro, the effect was related to activation of the PI3K/Akt and ERK1/2 signaling pathways. Suppression of these pathways by specific inhibitors, LY294002 and PD98059, partially reduced the protective effect of NaHS. Moreover, in the percutaneous needle puncture disc degeneration rat tail model, disc degeneration was partially reversed by NaHS administration. Taken together, our results suggest that H₂S plays a protective role in IVDD and the underlying mechanism involves PI3K/Akt and ERK1/2 signaling pathways-mediated suppression of ER stress and mitochondrial dysfunction in IL-1β-induced NP cells.

The effect of Chinese herbs and its effective components on coronary heart disease through PPARs-PGC1α pathway

Background

DanQi pill (DQP) is prescribed widely in China and has definite cardioprotective effect on coronary heart disease. Our previous studies proved that DQP could effectively regulate plasma levels of high density lipoprotein (HDL) and low density lipoprotein (LDL). However, the regulatory mechanisms of DQP and its major components Salvianolic acids and Panax notoginseng saponins (DS) on lipid metabolism disorders haven’t been comprehensively studied so far.

Methods

Rat model of coronary heart disease was induced by left anterior descending (LAD) artery ligation operations. Rats were divided into sham, model, DQP treated, DS treated and positive drug (clofibrate) treated groups. At 28 days after surgery, cardiac functions were assessed by echocardiography. Expressions of transcription factors and key molecules in energy metabolism pathway were measured by reverse transcriptase polymerase chain reaction or western blotting.

Results

In ischemic heart model, cardiac functions were severely injured but improved by treatments of DQP and DS. Expression of LPL was down-regulated in model group. Both DQP and DS could up-regulate the mRNA expression of LPL. Membrane proteins involved in lipid transport and uptake, such as FABP4 and CPT-1A, were down-regulated in ischemic heart tissues. Treatment with DQP and DS regulated lipid metabolisms by up-regulating expressions of FABP4 and CPT-1A. DQP and DS also suppressed expression of cytochrome P450. Furthermore, transcriptional factors, such as PPARα, PPARγ, RXRA and PGC-1α, were down-regulated in ischemic model group. DQP and DS could up-regulate expressions of these factors. However, DS showed a better efficacy than DQP on PGC-1α, a coactivator of PPARs. Key molecules in signaling pathways such as AKT1/2, ERK and PI3K were also regulated by DQP and DS simultaneously.

Conclusions

Salvianolic acids and Panax notoginseng are the major effective components of DanQi pill in improving lipid metabolism in ischemic heart model. The effects may be mediated by regulating transcriptional factors such as PPARs, RXRA and PGC-1α.

H2S biosynthesis and catabolism: new insights from molecular studies

Hydrogen sulfide (H₂S) has profound biological effects within living organisms and is now increasingly being considered alongside other gaseous signalling molecules, such as nitric oxide (NO) and carbon monoxide (CO). Conventional use of pharmacological and molecular approaches has spawned a rapidly growing research field that has identified H₂S as playing a functional role in cell-signalling and post-translational modifications. Recently, a number of laboratories have reported the use of siRNA methodologies and genetic mouse models to mimic the loss of function of genes involved in the biosynthesis and degradation of H₂S within tissues. Studies utilising these systems are revealing new insights into the biology of H₂S within the cardiovascular system, inflammatory disease, and in cell signalling. In light of this work, the current review will describe recent advances in H₂S research made possible by the use of molecular approaches and genetic mouse models with perturbed capacities to generate or detoxify physiological levels of H₂S gas within tissues.

The Effects of Hydrogen Sulfide on Adipocyte Viability in Human Adipocyte and Adipocyte-Derived Mesenchymal Stem Cell Cultures Under Ischemic Conditions

BACKGROUND

This study evaluated the in vitro effects of hydrogen sulfide on adipocyte survival under ischemic conditions and explored possible mechanisms of its apoptotic process.

METHODS

The mesenchymal stem cell culture was prepared from a human subcutaneous adipose tissue sample. Adipose-derived mesenchymal stem cells were differentiated into the adipogenic direction, and a mature adipocyte culture was obtained. The adipose-derived mesenchymal stem cell and mature adipocyte cultures were both divided into 6 groups. Sodium hydrogen sulfide was used as a hydrogen sulfide donor. After treating the groups with sodium hydrogen sulfide (0, 0.1, 1, 10, 100, and 1000 μM), the cell cultures were incubated in 1% oxygen at 37°C for 24 hours. After the ischemia period, the cell culture groups were evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test for the proliferation/cytotoxicity rates, flow cytometry for apoptosis and necrosis rates, and reverse transcriptase polymerase chain reaction for apoptotic (Bax, Caspase-3) and antiapoptotic (Bcl-2) gene expression levels.

RESULTS

Statistically significant increases in proliferation rates were found in mesenchymal stem cell groups treated with low dose (0, 1, and 1 μM) sodium hydrogen sulfide (P<0.05). For each dose, a statistically significant decrease was found in late apoptosis levels on the mature adipocyte cultures (P<0.05). In both cell culture groups, Bcl-2 gene expression was increased and Caspase-3 gene expression was decreased.

CONCLUSIONS

Under ischemic conditions, hydrogen sulfide has a protective effect on mesenchymal stem cells and mature adipocytes, and this effect is mediated by the elevation of antiapoptotic gene expression.

Remifentanil Preconditioning Reduces Postischemic Myocardial Infarction and Improves Left Ventricular Performance via Activation of the Janus Activated Kinase-2/Signal Transducers and Activators of Transcription-3 Signal Pathway and Subsequent Inhibition of Glycogen Synthase Kinase-3β in Rats

OBJECTIVES

Remifentanil preconditioning attenuates myocardial ischemia reperfusion injury, but the underlying mechanism is incompletely understood. The Janus activated kinase-2 (JAK2)/signal transducers and activators of transcription-3 (STAT3) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways are critical in both ischemic and pharmacologic preconditioning cardioprotection, which involve the inactivation of glycogen synthase kinase-3β. We hypothesized that remifentanil preconditioning confers cardioprotection via the JAK2/STAT3 and/or PI3K/Akt activation-mediated glycogen synthase kinase-3β inhibition.

DESIGN

Pharmacologic intervention.

SETTING

Research laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

In vivo and in vitro treatments.

MEASUREMENTS AND MAIN RESULTS

Male Sprague-Dawley rats (n = 6 per group) were sham operated or subjected to myocardial ischemia reperfusion injury. The JAK2 inhibitor AG490 (3 mg/kg), the PI3K inhibitor wortmannin (15 μg/kg), or the glycogen synthase kinase-3β inhibitor SB216763 (600 μg/kg) were given before inducing in vivo myocardial ischemia reperfusion injury achieved by occluding coronary artery for 30 minutes followed by 120 minutes of reperfusion in the absence or presence of remifentanil preconditioning (6 μg/kg/min). Also, isolated rat hearts were Langendorff perfused and subjected to 30 minutes of global ischemia and 120 minutes of reperfusion without or with remifentanil preconditioning (100 ng/mL) in the presence or absence of AG490 and/or SB216763. Isolated rat cardiomyocytes and H9C2 cells were subjected to hypoxia/reoxygenation alone or in combination with AG490 (100 μM), wortmannin (100 nM), or SB216763 (3 μM) without or with remifentanil preconditioning (2.5 μM). Remifentanil preconditioning reduced postischemic myocardial infarction and hemodynamic dysfunction induced by myocardial ischemia reperfusion injury concomitant with increased phosphorylation of STAT3 at tyr-705 (p-STAT3) and glycogen synthase kinase-3β but not Akt. AG490 but not wortmannin cancelled remifentanil preconditioning cardioprotection, and SB216763 restored it despite the presence of AG490. In Langendorff-perfused hearts, AG490-mediated cancellation of remifentanil preconditioning cardioprotection in attenuating postischemic myocardial infarction and creatinine kinase-MB release was reverted by concomitant administration of SB216763. Remifentanil preconditioning also attenuated posthypoxic cardiomyocyte injury and increased p-STAT3 and glycogen synthase kinase-3β in isolated primary cardiomyocytes and H9C2 cells. STAT3 gene knockdown with specific synthetic RNA cancelled remifentanil preconditioning cardioprotection, whereas glycogen synthase kinase-3β gene knockdown, which per se did not affect STAT3 under hypoxia/reoxygenation condition, preserved remifentanil preconditioning cardioprotection regardless of STAT3 abrogation.

CONCLUSIONS

Remifentanil preconditioning confers cardioprotection primarily via activation of JAK2/STAT3 signaling that can function independent of PI3K/Akt activation. Glycogen synthase kinase-3β is a critical downstream effector of remifentanil preconditioning cardioprotection.

Sensitivity of Interfibrillar and Subsarcolemmal Mitochondria to Cobalt Chloride-induced Oxidative Stress and Hydrogen Sulfide Treatment

Oxidative stress plays a significant role not only in cardiovascular disease but also in non-communicable diseases, where it plays a significant role the mortality rate. Hydrogen sulfide, the biological gaseous signaling molecule that preserves mitochondria in its mode of action, is an effective cardioprotective drug. However, cardiac mitochondria comprise of two distinct populations, namely interfibrillar and subsarcolemmal mitochondria, which respond distinctly in cardiovascular disease. This study was designed to determine the direct impact of cobalt chloride-induced oxidative stress in isolated mitochondrial subpopulations with an intention to examine the efficacy of hydrogen sulfide in preserving interfibrillar and subsarcolemmal mitochondria functional activities when they were incubated as pretreated, co-treated and post-treated agent. Mitochondrial subpopulations were isolated from the heart of male Wistar rats and subjected to cobalt chloride treatment (500 μM) for 20 min, followed by incubation with 10 μM sodium hydrosulfide in three different ways (Pre, Co, and Post-cobalt chloride treatment). Mitochondrial oxidative stress was measured by the concentration of thiobarbituric acid reactive species, reduced glutathione and the activities of enzymes like superoxide dismutase, catalase and glutathione peroxidase. Mitochondrial membrane potential, swelling behavior and enzyme activities were measured to assess its function. The increased level of lipid peroxidation and the decreased level of reduced glutathione in cobalt chloride-induced group confirm the induction of oxidative stress and were more predominant in the subsarcolemmal mitochondria. Hydrogen sulfide treatment to interfibrillar and subsarcolemmal mitochondria preserved their functional activities, but the effect was prominent only with co-treated group. In conclusion, the present study demonstrated that subsarcolemmal mitochondria are more prone to oxidative stress and the co-treatment of the mitochondria with hydrogen sulfide preserved the enzyme activity in the in vitro conditions.

Hydrogen sulphide in cardiovascular system: A cascade from interaction between sulphur atoms and signalling molecules

As a gasotransmitter, hydrogen sulphide exerts its extensive physiological and pathophysiological effects in mammals. The interaction between sulphur atoms and signalling molecules forms a cascade that modulates cellular functions and homeostasis. In this review, we focus on the signalling mechanism underlying the effect of hydrogen sulphide in the cardiovascular system and metabolism as well as the biological relevance to human diseases.

Hydroxytyrosol Protects against Myocardial Ischemia/Reperfusion Injury through a PI3K/Akt-Dependent Mechanism

Objective. To investigate the effects and mechanisms of hydroxytyrosol (HT) during the pathogenesis of myocardial ischemia reperfusion (I/R) in rat hearts. Methods. The rats were randomized into five groups: sham group, I/R group, HT+I/R group, HT+LY294002+I/R group, and LY+I/R group. Myocardial infarct size, markers of oxidative stress, extent of myocardial apoptosis, echocardiographically assessed cardiac function, and expression of Akt and GSK 3β were measured in each group. Results. Prereperfusion administration of HT was associated with a significantly smaller area of myocardial infarction and remarkably decreased level of myocardial apoptosis and necrosis, as evidenced by a lower apoptotic index, reduced cleaved caspase-3, and the serum activities of lactate dehydrogenase and creatinine kinase MB. Moreover, HT also attenuated the impairment of cardiac systolic function. However, cotreatment with LY294002 and HT completely abolished the above cardioprotective effects of HT. A subsequent mechanistic study revealed that the cardioprotective effects of HT during the process of I/R of the myocardium were dependent on the activation of the Akt/GSK3β pathway. Conclusion. Pretreatment with HT may have antiapoptotic and cardioprotective effects against myocardial I/R injury, and these effects seem to be related to the activation of the Akt/GSK3β pathway in the myocardium.

Panax Notoginseng Saponins Ameliorates Coxsackievirus B3-Induced Myocarditis by Activating the Cystathionine-γ-Lyase/Hydrogen Sulfide Pathway

This study is to determine the therapeutic effects of Panax notoginseng saponins (PNSs) on coxsackievirus B3 (CVB3)-induced myocarditis, and whether cystathionine-γ-lyase (CSE)/hydrogen sulfide (H2S) pathway is involved. Mouse model of myocarditis was induced by CVB3 infection, and the mice were subjected to vehicle (saline) or drug treatments (sodium bisulfide (NaHS), propargylglycine (PAG), or PNSs). The results showed that there were inflammatory cell infiltrations, interstitial edemas, and elevated inflammatory cytokines, in CVB3-induced myocarditis. PAG administration increased, whereas NaHS treatment decreased the severity of the myocarditis. PNS treatment dramatically alleviated these myocardial injuries and decreased the viral messenger RNA (mRNA) expression by the enhanced expression of CSE/H2S pathway. Moreover, the therapeutic effects of PNSs on myocarditis were stronger than those of NaHS. Finally, the effect of PNSs on CSE/H2S pathway and cardiac cell protection were verified in cultured cardiac cells. PNSs may be a promising medication for viral myocarditis therapy.

Endogenously produced hydrogen sulfide is involved in porcine oocyte maturation in vitro

Hydrogen sulfide, one of three known gasotransmitters, is involved in physiological processes, including reproductive functions. Oocyte maturation and surrounding cumulus cell expansion play an essential role in female reproduction and subsequent embryonic development. Although the positive effects of exogenous hydrogen sulfide on maturing oocytes are well known, the role of endogenous hydrogen sulfide, which is physiologically released by enzymes, has not yet been described in oocytes. In this study, we observed the presence of Cystathionine β-Synthase (CBS), Cystathionine γ-Lyase (CTH) and 3-Mercaptopyruvate Sulfurtransferase (3-MPST), hydrogen sulfide-releasing enzymes, in porcine oocytes. Endogenous hydrogen sulfide production was detected in immature and matured oocytes as well as its requirement for meiotic maturation. Individual hydrogen sulfide-releasing enzymes seem to be capable of substituting for each other in hydrogen sulfide production. However, meiosis suppression by inhibition of all hydrogen sulfide-releasing enzymes is not irreversible and this effect is a result of M-Phase/Maturation Promoting Factor (MPF) and Mitogen-Activated Protein Kinase (MAPK) activity inhibition. Futhermore, cumulus expansion expressed by hyaluronic acid (HA) production is affected by the inhibition of hydrogen sulfide production. Moreover, quality changes of the expanded cumuli are indicated. These results demonstrate hydrogen sulfide involvement in oocyte maturation as well as cumulus expansion. As such, hydrogen sulfide appears to be an important cell messenger during mammalian oocyte meiosis and adequate cumulus expansion.

PI3K/SGK1/GSK3β signaling pathway is involved in inhibition of autophagy in neonatal rat cardiomyocytes exposed to hypoxia/reoxygenation by hydrogen sulfide

Excessive autophagy aggravates myocardial ischemia/reperfusion (IR) injury. Hydrogen sulfide (H2S) has been shown to possess a strong cardioprotective effect due to its anti-necrosis, anti-apoptosis, anti-oxidant and anti-inflammatory properties. Our previous study showed that H2S could also protect the myocardium against IR injury through its anti-autophagy effect in vivo, but the underlying mechanism remains unclear. The aim of the present study was to determine whether PI3K/SGK1/GSK3β signaling pathway was involved in the anti-autophagy effect of H2S against myocardial hypoxia/reoxygenation (HR) injury in vitro. Autophagy was significantly increased in cardiomyocytes subjected to HR, but it was down-regulated by H2S (NaHS donor). Blocking PI3K by LY294002 (a PI3K inhibitor) or knocking down SGK1 by SGK1 siRNA augmented autophagy and attenuated the anti-autophagy effect of H2S. However, blocking GSK3β by tws119 (a GSK3β inhibitor) produced an opposite effect. In addition, while treatment of neonatal rat cardiomyocytes with HR reduced cell viability and augmented cell injury, H2S significantly reversed it. Blocking PI3K or knocking down SGK1 aggravated HR injury and weakened the protective effect of H2S, while blocking GSK3β produced an opposite effect. In conclusion, H2S can inhibit autophagy in neonatal rat cardiomyocytes exposed to H/R and exert a cardioprotective effect at least partly by regulating PI3K/SGK1/GSK3β signaling pathway.

[Hydrogen sulfide: A promising therapy in neuroprotection following cardiac arrest?]

Each year, in France, the number of cardiac arrests is evaluated between 30,000 to 50,000. When a patient survives, he undergoes a post-resuscitation syndrome which can aggravate the injuries and for which nowadays, no medication is available. In some kinds of cardiac arrest, a hypothermia protocol can be applied with a need for monitoring because of the appearance of side effects. In this context, hydrogen sulfide, which is a gasotransmitter with numerous physiological and pharmacological properties, may be interesting. Indeed, its use could protect against oxidative, inflammatory and apoptotic troubles induced by the post-resuscitation syndrome. The implied biochemical mechanisms are adenosine triphosphate potassium channels activation and cytochrome c oxidase inhibition. This molecule can also induce a suspended animation state characterized by a metabolism decrease, which could give a delay for physicians to start a therapeutic monitoring. Thus, in spite of a modest and sometimes contradictory literature, this compound could become the first neuroprotective molecule in cardiac arrest.

Hydrogen Sulfide Levels and Nuclear Factor-Erythroid 2-Related Factor 2 (NRF2) Activity Are Attenuated in the Setting of Critical Limb Ischemia (CLI)

Background

Cystathionine γ-lyase, cystathionine β-synthase, and 3-mercaptopyruvate sulfurtransferase are endogenous enzymatic sources of hydrogen sulfide (H₂S). Functions of H₂S are mediated by several targets including ion channels and signaling proteins. Nuclear factor-erythroid 2-related factor 2 is responsible for the expression of antioxidant response element–regulated genes and is known to be upregulated by H₂S. We examined the levels of H₂S, H₂S-producing enzymes, and nuclear factor-erythroid 2-related factor 2 activation status in skeletal muscle obtained from critical limb ischemia (CLI) patients.

Methods and Results

Gastrocnemius tissues were attained postamputation from human CLI and healthy control patients. We found mRNA and protein levels of cystathionine γ-lyase, cystathionine β-synthase, and 3-mercaptopyruvate sulfurtransferase were significantly decreased in skeletal muscle of CLI patients as compared to control. H₂S and sulfane sulfur levels were significantly decreased in skeletal muscle of CLI patients. We also observed significant reductions in nuclear factor-erythroid 2-related factor 2 activation as well as antioxidant proteins, such as Cu, Zn-superoxide dismutase, catalase, and glutathione peroxidase in skeletal muscle of CLI patients. Biomarkers of oxidative stress, such as malondialdehyde and protein carbonyl formation, were significantly increased in skeletal muscle of CLI patients as compared to healthy controls.

Conclusions

The data demonstrate that H₂S bioavailability and nuclear factor-erythroid 2-related factor 2 activation are both attenuated in CLI tissues concomitant with significantly increased oxidative stress. Reductions in the activity of H₂S-producing enzymes may contribute to the pathogenesis of CLI.

Role of Hydrogen Sulfide in Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is one of the major causes of high morbidity, disability, and mortality in the world. I/R injury remains a complicated and unresolved situation in clinical practice, especially in the field of solid organ transplantation. Hydrogen sulfide (H₂S) is the third gaseous signaling molecule and plays a broad range of physiological and pathophysiological roles in mammals. H₂S could protect against I/R injury in many organs and tissues, such as heart, liver, kidney, brain, intestine, stomach, hind-limb, lung, and retina. The goal of this review is to highlight recent findings regarding the role of H₂S in I/R injury. In this review, we present the production and metabolism of H₂S and further discuss the effect and mechanism of H₂S in I/R injury.

Hydrogen Sulfide Prevents Advanced Glycation End-Products Induced Activation of the Epithelial Sodium Channel

Advanced glycation end-products (AGEs) are complex and heterogeneous compounds implicated in diabetes. Sodium reabsorption through the epithelial sodium channel (ENaC) at the distal nephron plays an important role in diabetic hypertension. Here, we report that H₂S antagonizes AGEs-induced ENaC activation in A6 cells. ENaC open probability (P_O) in A6 cells was significantly increased by exogenous AGEs and that this AGEs-induced ENaC activity was abolished by NaHS (a donor of H₂S) and TEMPOL. Incubating A6 cells with the catalase inhibitor 3-aminotriazole (3-AT) mimicked the effects of AGEs on ENaC activity, but did not induce any additive effect. We found that the expression levels of catalase were significantly reduced by AGEs and both AGEs and 3-AT facilitated ROS uptake in A6 cells, which were significantly inhibited by NaHS. The specific PTEN and PI3K inhibitors, BPV_(pic) and LY294002, influence ENaC activity in AGEs-pretreated A6 cells. Moreover, after removal of AGEs from AGEs-pretreated A6 cells for 72 hours, ENaC P_O remained at a high level, suggesting that an AGEs-related “metabolic memory” may be involved in sodium homeostasis. Our data, for the first time, show that H₂S prevents AGEs-induced ENaC activation by targeting the ROS/PI3K/PTEN pathway.

Saffron extracts alleviate cardiomyocytes injury induced by doxorubicin and ischemia-reperfusion in vitro

Doxorubicin (DOX), a highly active chemotherapeutic drug, faces limitations in clinical application due to severe cardiotoxic effects (mainly through increased oxidative stress). Therefore, its effect is exacerbated in subjects with ischemic heart disease. We have recently reported that saffron extract (SAF), a natural compound mainly consisting of safranal and corcins, exerts a protective effect against DOX oxidative cytotoxicity in isolated rabbit hearts. Here, we aimed to investigate whether SAF exerts cardioprotection against combined ischemia-reperfusion (I/R) and DOX toxicity in H9c2 cardiomyocytes. H9c2 were subjected to simulated I/R, with or without DOX treatment at reperfusion, in the presence or absence of SAF prior to ischemia or at reperfusion. We evaluated the effects of these treatments by MTT, LDH and western blot analysis. Apoptosis was assessed by Hoechst 33258 staining, tetramethyl rhodamine methyl ester fluorescence and caspase activity. The results showed that I/R and DOX significantly decreased cardiomyocytes viability, inhibited reperfusion injury salvage kinase cardioprotective pathway, reduced contractile proteins (α-Actinine, Troponine C and MLC), increased caspase-3 expression and induced loss of mitochondrial membrane potential. These effects were remarkably inhibited by treatment with SAF (10 μg/mL) at reperfusion. SAF activated AKT/P70S6K and ERK1/2, restored contractile proteins expression, inhibited mitochondrial permeability transition pore and decreased caspase-3 activity. In conclusion, our findings indicate that SAF treatment exerted cardioprotection against I/R and DOX toxicity by reducing oxidative stress (LDH assay). Thereby, SAF offers a potential novel antioxidant therapeutic strategy to counteract I/R and DOX cardiotoxicity, paving the way for future clinical trials.