The effects of therapeutic sulfide on myocardial apoptosis in response to ischemia-reperfusion injury

Ozone Administration Reduces Myocardial Ischemia Reperfusion Injury in Streptozotocin Induced Diabetes Mellitus Rat Model

Objective

This study aimed to demonstrate whether ozone has cardioprotective effects on the myocardial ischemia-reperfusion injury (IRI) in rats with streptozotocin(STZ)-induced diabetes.

Methods

A total of 38 male Wistar Albino rats were divided into five groups as follows: control group (group C,n=6), diabetic group (group D,n=6), diabetic ozone group (group DO,n=6), diabetic-ischemia/reperfusion (group DIR,n=6), diabetic-ischemia/reperfusion-ozone (group DIRO,n=6). Six rats died during this period and two died because of surgical complications. A myocardial ischemia-reperfusion model was created using a thoracotomy incision from 4th intercostal space. The LAD was ligated using an 8-0 prolene suture for 30min. Ozone was administered intraperitoneally(1mg/kg) 5min before reperfusion. The reperfusion time was 120 min. At the end of the reperfusion procedure, myocardial tissue histopathological examinations, and serum biochemical analyses were performed.

Results

The percentage of TUNEL(+) cardiomyocytes/HPF was significantly higher in the DIR group than in the C, D, and DO groups. Conversely, TUNEL positivity was significantly lower in the DIRO group than in the DIR group. The IRI score was significantly higher in the DIR and DIRO groups than that in the C, D, and DO groups. In contrast, the IRI damage score in the DIRO group was significantly lower than that in the DIR group. Serum MDA levels were significantly higher in the DIR group than in the C, D, and DO groups. Similarly, MDA levels were significantly higher in the DIRO group than in the C and D groups. CAT activity was significantly higher in the DIR group than in the C and D groups. SOD activity was significantly higher in the DIR group than in the C and DO groups.

Conclusion

Our study showed that ozone exerts cardioprotective effects in STZ-induced diabetic rats through its antioxidant role against oxidative stress. Both biochemical and histological analyses clearly revealed that ozone has beneficial effects against IRI in the diabetic rat myocardium.

Progress in the Study of Chemical Structure and Pharmacological Effects of Total Paeony Glycosides Isolated from Radix Paeoniae Rubra

Radix paeoniae rubra, known as red peony root, is derived from the dried roots of Paeonia lactiflora pall or Paeonia veitchii lynch from the Ranunculaceae family. It is recognized for its properties of clearing heat, cooling blood, dispelling stasis, and alleviating pain, making it one of the most commonly used herbs in traditional Chinese medicine. Total paeony glycosides (TPGs) are identified as the principal active constituents of Radix paeoniae rubra, comprising monoterpenoid compounds with a cage-like pinane structure and monoterpenoids with a lactone structure. This review summarizes the chemical constituents and pharmacological effects of TPGs, with the aim of elucidating their relationships.

BECN1 regulates FADD/RIPK1/Caspase-8 complex formation via RIPK1 ubiquitination by downregulating OTUD1 in MI/R induced myocyte apoptosis

BACKGROUND

Cardiomyocyte apoptosis plays a vital role in myocardial ischemia-reperfusion (MI/R) injury; however, the role of beclin1 (BECN1) remains unclear. This study aimed at revealing the function of BECN1 during cardiomyocyte apoptosis after MI/R injury.

METHODS

In vivo, TTC and Evan's blue double staining was applied to verify the gross morphological alteration in both wild type (WT) mice and BECN1 transgene mice (BECN1-TG), and TUNEL staining and western blot were adopted to evaluate the cardiomyocyte apoptosis. In vitro, a hypoxia/reoxygenation (H/R) model was established in H9c2 cells to simulate MI/R injury. Proteomics analysis was preformed to verify if apoptosis occurs in the H/R cellular model. And apoptosis factors, RIPK1, Caspase-1, Caspase-3, and cleaved Caspase-3, were investigated using western bolting. In addition, the mRNA level were verified using RT-PCR. To further investigate the protein interactions small interfering RNA and lentiviral transfection were used. To continue investigate the protein interactions, immunofluorescence and coimmunoprecipitation were applied.

RESULTS

Morphologically, BECN1 significantly attenuated the apoptosis from TTC-Evan's staining, TUNEL, and cardiac tissue western blot. After H/R, a RIPK1-induced complex (complex II) containing RIPK1, Caspase-8, and FADD was formed. Thereafter, cleaved Caspase-3 was activated, and myocyte apoptosis occurred. However, BECN1 decreased the expression of RIPK1, Caspase-8, and FADD. Nevertheless, BECN1 overexpression increased RIPK1 ubiquitination before apoptosis by inhibiting OTUD1.

CONCLUSIONS

BECN1 regulates FADD/RIPK1/Caspase-8 complex formation via RIPK1 ubiquitination by downregulating OTUD1 in C-Caspase-3-induced myocyte apoptosis after MI/R injury. Therefore, BECN1 can function as a cardioprotective candidate.

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.

Exploring Iodide and Hydrogen Sulfide as ROS Scavengers to Delay Acute Rejection in MHC-Defined Vascularized Composite Allografts

Vascularized composite allografts (VCA) face ischemic challenges due to their limited availability. Reperfusion following ischemia triggers oxidative stress and immune reactions, and scavenger molecules could mitigate ischemia-reperfusion injuries and, therefore, immune rejection. We compared two scavengers in a myocutaneous flap VCA model. In total, 18 myocutaneous flap transplants were performed in Major histocompatibility complex (MHC)-defined miniature swine. In the MATCH group (n = 9), donors and recipients had minor antigen mismatch, while the animals were fully mismatched in the MISMATCH group (n = 9). Grafts were pretreated with saline, sodium iodide (NaI), or hydrogen sulfide (H2S), stored at 4 °C for 3 h, and then transplanted. Flaps were monitored until clinical rejection without immunosuppression. In the MATCH group, flap survival did not significantly differ between the saline and hydrogen sulfide treatments (p = 0.483) but was reduced with the sodium iodide treatment (p = 0.007). In the MISMATCH group, survival was similar between the saline and hydrogen sulfide treatments (p = 0.483) but decreased with the sodium iodide treatment (p = 0.007). Rhabdomyolysis markers showed lower but non-significant levels in the experimental subgroups for both the MATCH and MISMATCH animals. This study provides insightful data for the field of antioxidant-based approaches in VCA and transplantation.

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.

Nrf2 for a key member of redox regulation: A novel insight against myocardial ischemia and reperfusion injuries

Nuclear factor erythroid-2 related factor 2 (Nrf2), a nuclear transcription factor, modulates genes responsible for antioxidant responses against toxic and oxidative stress to maintain redox homeostasis and participates in varieties of cellular processes such as metabolism and inflammation during myocardial ischemia and reperfusion injuries (MIRI). The accumulation of reactive oxygen species (ROS) from damaged mitochondria, xanthine oxidase, NADPH oxidases, and inflammation contributes to depraved myocardial ischemia and reperfusion injuries. Considering that Nrf2 played crucial roles in antagonizing oxidative stress, it is reasonable to delve into the up or down-regulated molecular mechanisms of Nrf2 in the progression of MIRI to provide the possibility of new therapeutic medicine targeting Nrf2 in cardiovascular diseases. This review systematically describes the generation of ROS, the regulatory metabolisms of Nrf2 as well as several natural or synthetic compounds activating Nrf2 during MIRI, which might provide novel insights for the anti-oxidative stress and original ideas targeting Nrf2 for the prevention and treatment in cardiovascular diseases.

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.

Reperfusion-induced injury and the effects of the dithioacetate type hydrogen sulfide donor ibuprofen derivative, BM-88, in isolated rat hearts

Hydrogen sulfide (H₂S) plays an important role in cardiac protection by regulating various redox signalings associated with myocardial ischemia/reperfusion (I/R) induced injury. The goal of the present investigations is the synthesis of a newly designed H₂S-releasing ibuprofen derivative, BM-88, and its pharmacological characterization regarding the cardioprotective effects in isolated rat hearts. Cytotoxicity of BM-88 was also estimated in H9c2 cells. H₂S-release was measured by an H₂S sensor from the coronary perfusate. Increasing concentrations of BM-88 (1.0 to 20.0 µM) were tested in in vitro studies. Preadministration of 10 µM BM-88 significantly reduced the incidence of reperfusion-induced ventricular fibrillation (VF) from its drug-free control value of 92% to 12%. However, no clear dose dependent reduction in the incidence of reperfusion-induced VF was observed while different concentrations of BM-88 were used. It was also found that 10 µM BM-88 provided a substantial protection and significantly reduced the infarct size in the ischemic/reperfused myocardium. However, this cardiac protection was not reflected in any significant changes in coronary flow and heart rates. The results support the fact that H₂S release plays an important role mitigating reperfusion-induced cardiac damage.

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.

A single-wavelength excited NIR fluorescence probe for distinguishing GSH/H2S and Cys/Hcy in living cells and zebrafish through separated dual-channels

Biothiols and hydrogen sulfide, as critical sulfur-containing reactive substances, serve essential functions in various human pathological processes, making it challenging to simultaneously distinguish them due to their similar reactivity and structures (-SH). Here, we rationalized the development of a single-wavelength excitation near-infrared (NIR) fluorescence probe, FC-NBD, for distinguishing GSH/H₂S and Cys/Hcy by separated fluorescence dual channels. In this probe, FC-NBD, composed of coumarin-benzopyrylium derivatives linked with nitro benzoxadiazole (NBD) via ether bonds, could quantitatively and selectively distinguish GSH/H₂S and Cys/Hcy with a low limit of detection (LOD) of 0.199/0.177 μM and 0.106/0.076 μM, respectively. As expected, under single-wavelength excitation (470 nm), FC-NBD demonstrated distinctly separable green and NIR fluorescence emissions towards Cys/Hcy at 550 and 660 nm, but only exhibited a noticeable NIR fluorescence emission towards GSH/H₂S at 660 nm. Moreover, FC-NBD could simultaneously visualize and discriminate GSH/H₂S and Cys/Hcy in living cells as well as zebrafish through green and NIR channels at a single excitation wavelength.

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.

The Protective Effects of miR-21-Mediated Fibroblast Growth Factor 1 in Rats with Coronary Heart Disease

Aim

The study is to verify the protective effects of miR-21-mediated fibroblast growth factor 1 (FGF1) against myocardial ischemia in rats with coronary heart disease.

Materials and Methods

Sprague-Dawley (SD) rat models of myocardial ischemia/reperfusion (MI/R) injury were constructed, and the expression of miR-21 and FGF1 in them was interfered through ischemic postconditioning. The protective effects of miR-21-mediated FGF1 on myocardium of the model rats were analyzed, and the targeted regulatory relationship between miR-21 and FGF1 was verified through myocardial cell experiments to find the mechanism of miR-21.

Results

MiR-21 and FGF1 with increased expression could protect the cardiac function of model rats and improve their diastolic blood pressure (DBP), systolic blood pressure (SBP), heart rate (HR), coronary flow (CF), bax, and bcl-2 levels, but it would also cause further increase of vascular endothelial growth factor (VEGF) and decreased infarct size (INF). In addition, intervention through both miR-21 mimics and recombinant human FGF1 could highlight the above changes. Pearson correlation analysis revealed that the expression of miR-21 was positively correlated with that of FGF1, and both miR-21 and FGF1 were significantly and linearly correlated with DBP, SBP, HR, CF, INF, bax, and bcl-2, but they were not significantly correlated with the VEGF level. The myocardial cell experiment results revealed that upregulation of miR-21 or FGF1 could alleviate apoptosis caused by hypoxia/reoxygenation of myocardial cells, and inhibition of the FGF1 expression could hinder the effect of miR-21 against apoptosis of myocardial cells. Dual luciferase reporter assay revealed that transfection of miR-21-mimics could effectively raise the fluorescence intensity of pmirGLO-FGF1-3′UTR Wt but had no significant effect on that of pmirGLO-FGF1-3′UTR Mut.

Conclusion

MiR-21 can specifically mediate the expression of FGF1 to relieve MI/R injury, protect the cardiac function, and resist apoptosis.

The Antioxidant Transcription Factor Nrf2 in Cardiac Ischemia-Reperfusion Injury

Nuclear factor erythroid-2 related factor 2 (Nrf2) is a transcription factor that controls cellular defense responses against toxic and oxidative stress by modulating the expression of genes involved in antioxidant response and drug detoxification. In addition to maintaining redox homeostasis, Nrf2 is also involved in various cellular processes including metabolism and inflammation. Nrf2 activity is tightly regulated at the transcriptional, post-transcriptional and post-translational levels, which allows cells to quickly respond to pathological stress. In the present review, we describe the molecular mechanisms underlying the transcriptional regulation of Nrf2. We also focus on the impact of Nrf2 in cardiac ischemia-reperfusion injury, a condition that stimulates the overproduction of reactive oxygen species. Finally, we analyze the protective effect of several natural and synthetic compounds that induce Nrf2 activation and protect against ischemia-reperfusion injury in the heart and other organs, and their potential clinical application.

Effects of maslinic acid on cardiac function in ischemia-reperfusion injury rats

Maslinic acid (MA), a pentacyclic triterpenoid, has been reported to exert broad pharmacological properties. However, it is still unclear whether MA exhibits protective effects against ischemia/reperfusion (I/R) injury. Herein, we aimed to investigate the effects of MA on I/R injury and its underlying mechanisms. A rat model of I/R injury was established and administrated with MA by intraperitoneal injection. Cardiac function was assessed with a color ultrasound diagnosis system and PowerLab system. The levels of oxidative stress-related and I/R-related biomarkers were evaluated by using commercial kits. Apoptosis-related biomarkers and sirtuin (SIRT)1/AMP-activated protein kinase (AMPK) signaling proteins were determined by using quantitative reverse transcription PCR and western blotting, respectively. Treatment with MA improved cardiac performance and cardiac hemodynamic parameters in the I/R injury rat model. Besides, treatment with MA (20 mg/kg) ameliorated I/R injury-related biomarkers in serum. Interestingly, treatment with MA (20 mg/kg) also regulated myocardial apoptosis and inhibited oxidative-stress in left ventricular tissue. Mechanistic studies demonstrated that MA upregulated SIRT1 and AMPK phosphorylation in the left ventricular tissue. In summary, MA exerted protective effects against the impairments of cardiac function in I/R injury rats by the regulation of SIRT1/AMPK signaling pathways.

The potential relationship between gasotransmitters and oxidative stress, inflammation and apoptosis in lead-induced hepatotoxicity in rats

The interrelationship between gasotransmitters and oxidative stress, inflammation and apoptosis in lead-induced hepatotoxicity was investigated in this study. On prolonged exposure, lead was accumulated in liver tissue of rats and impaired liver function and structure as assessed by measurement of the serum hepatic function markers and by histopathological examination. The accumulated metal induced oxidative stress, inflammation and apoptosis in the liver. Also, it increased nitric oxide (NO) production and decreased hydrogen sulfide (H₂S) level and heme oxygenase (HO-1) concentration in liver tissue. Decreasing of NO production by L-N(G)-nitroarginine methyl ester (L-NAME) and increasing of H₂S level by sodium hydrosulfide (NaHS) and carbon monoxide (CO) level by carbon monoxide-releasing molecule-A₁ (CORM-A₁) inhibited lead-induced impairment of liver function and structure. Concomitantly, these agents inhibited lead intoxication-induced oxidative stress, inflammation, apoptosis, nitrosative stress and reduction of HO-1 concentration and H₂S level. Furthermore, concurrent treatment with these agents inhibited lead intoxication-induced increase in the protein expressions of inducible NO synthase, tumor necrosis factor-alpha, interleukin-1beta and caspase-3 as well as decrease in protein expressions of HO-1 and cystathionine-γ-lyase in the liver. NO donor, l-arginine and H₂S and CO biosynthesis inhibitors, trifluoro-DL-alanine and zinc deutroporphyrin, respectively aggravated the toxic effects of lead. These results indicate, for the first time, that there is an interrelationship between gasotransmitters and lead-induced hepatotoxicity. The ability of L-N AME, NaHS and CORM-A₁ to provide protective effects against lead-induced hepatotoxicity may positively correlate, to their ability to suppress hepatic oxidative stress, nitrosative stress, inflammation and apoptosis.

Novel controlled and targeted releasing hydrogen sulfide system exerts combinational cerebral and myocardial protection after cardiac arrest

BACKGROUND

Cardiac arrest (CA) is a leading cause of death worldwide. Even after successful cardiopulmonary resuscitation (CPR), the majorities of survivals are companied with permanent myocardial and cerebral injury. Hydrogen sulfide (H2S) has been recognized as a novel gasotransmitter exerting multiple organ protection; however, the lacks of ideal H2S donors which can controlled release H2S to targeted organs such as heart and brain limits its application.

RESULTS

This work utilized mesoporous iron oxide nanoparticle (MION) as the carriers of diallyl trisulfide (DATS), with polyethylene glycol (PEG) and lactoferrin (LF) modified to MIONs to acquire the prolonged circulation time and brain-targeting effects, and a novel targeted H2S releasing system was constructed (DATS@MION-PEG-LF), which exhibited excellent biocompatibility, controlled-releasing H2S pattern, heart and brain targeting features, and the ability to be non-invasive traced by magnetic resonance imaging. DATS@MION-PEG-LF presented potent protective effects against cerebral and cardiac ischemic injury after CA in both in vitro hypoxia/reoxygenation models and in vivo CA/CPR models, which mainly involves anti-apoptosis, anti-inflammatory and anti-oxidant mechanisms. Accordingly, the cardiac and cerebral functions were obviously improved after CA/CPR, with potentially improved survival.

CONCLUSIONS

The present work provides a unique platform for targeted controlled release of H2S based on MIONs, and offers a new method for combinational myocardial and cerebral protection from ischemic injury, bringing considerable benefits for CA patients.

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.

Chronic Treatment With Hydrogen Sulfide Donor GYY4137 Mitigates Microglial and Astrocyte Activation in the Spinal Cord of Streptozotocin-Induced Diabetic Rats

Long-term diabetic patients suffer immensely from diabetic neuropathy. This study was designed to investigate the effects of hydrogen sulfide (H2S) on peripheral neuropathy, activation of microglia, astrocytes, and the cascade secretion of proinflammatory cytokines in the streptozotocin (STZ)-induced peripheral diabetic neuropathy rat model. STZ-induced diabetic rats were treated with the water-soluble, slow-releasing H2S donor GYY4137 (50 mg/kg; i.p.) daily for 4 weeks. Antiallodynic/antihyperalgesic activities were evaluated using different tests and histopathological changes and the expression of proinflammatory cytokines in the spinal cord were examined. GYY4137 treatment produced neuroprotective effects in the spinal cord of diabetic animals and modulated their sensory deficits. The treatment decreased allodynia (p < 0.05) and mechanical hyperalgesia (p < 0.01) and restored thermal hyperalgesia (p < 0.001) compared with diabetic rats. The treatment decreased the microglial response and increased astrocyte counts in spinal cord gray and white matter compared with untreated diabetic rats. Proinflammatory cytokines were reduced in the treated group compared with diabetic rats. These results suggest that H2S has a potentially ameliorative effect on the neuropathic pain through the control of astrocyte activation and microglia-mediated inflammation, which may be considered as a possible treatment of peripheral nerve hypersensitivity in diabetic patients.

E3-ubiquitin ligase TRIM6 aggravates myocardial ischemia/reperfusion injury via promoting STAT1-dependent cardiomyocyte apoptosis

Cardiomyocyte apoptosis is a major cause of myocardial ischemia/reperfusion (MI/R) injury, in which the activation of the signal transducer and activator of transcription 1 (STAT1) plays an important role. The E3-ubiquitin ligase TRIM6 has been implicated in regulating STAT1 activity, however, whether it is associated with MI/R injury and the underlying mechanism are not determined. In this study, by investigating a mouse MI/R injury model, we show that TRIM6 expression is induced in mouse heart following MI/R injury. Additionally, TRIM6 depletion reduces and its overexpression increases myocardial infarct size, serum creatine phosphokinase (CPK) level and cardiomyocyte apoptosis in mice subjected to MI/R injury, indicating that TRIM6 functions to aggravate MI/R injury. Mechanistically, TRIM6 promotes IKKε-dependent STAT1 activation, and the inhibition of IKKε or STAT1 with the specific inhibitor, CAY10576 or fludarabine, abolishes TRIM6 effects on cardiomyocyte apoptosis and MI/R injury. Similarly, TRIM6 mutant lacking the ability to ubiquitinate IKKε and induce IKKε/STAT1 activation also fails to promote cardiomyocyte apoptosis and MI/R injury. Thus, these results suggest that TRIM6 aggravates MI/R injury through promoting IKKε/STAT1 activation-dependent cardiomyocyte apoptosis, and that TRIM6 might represent a novel therapeutic target for alleviating MI/R injury.

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.

Cilostazol protects against myocardial ischemia and reperfusion injury by activating transcription factor EB (TFEB)

Although cilostazol was proved to have antitumor biological effects, its function in myocardial ischemia and reperfusion (I/R) injury and the underlying mechanisms were not fully illustrated yet. In this study, a rat model of I/R injury was constructed and quantitative real-time PCR, Western blot, and immunofluorescence (IF) assay were performed. Our results showed that cilostazol increased LC3 II/LC3 I ratio, reduced p62 abundance, and promoted the expressions of LAMP1, LAMP2, cathepsin B, and cathepsin D, indicating that cilostazol could activate autophagy and elevated lysosome activation. Following analysis showed that cilostazol enhanced nuclear protein expression of transcription factor EB (TFEB), an important regulator of autophagy-lysosome pathway. Furthermore, CCI-779, an inhibitor of TFEB, could reverse the effects of cilostazol on autophagic activity and lysosome activation. Importantly, cilostazol suppressed I/R injury-induced apoptosis by decreasing the cleavage of caspase 3 and PARP. Enzyme-linked immunosorbent assay showed that cilostazol reduced the serum levels of CTn1 and CK-MB and decreased infract size caused by I/R injuries. Altogether this study suggested that cilostazol protects against I/R injury by regulating autophagy, lysosome, and apoptosis in a rat model of I/R injury. The protective mechanism of cilostazol was partially through increasing the transcriptional activity of TFEB.

The Role of Inflammatory Cytokines in Cardiac Arrest

Introduction:

Post-cardiac arrest syndrome (PCAS) is characterized by systemic ischemia/reperfusion injury, anoxic brain injury, and post-arrest myocardial dysfunction superimposed on a precipitating pathology. The role of inflammatory cytokines in cardiac arrest remains unclear.

Aims:

We aimed to describe, with an emphasis on clinical applications, what is known about the role of inflammatory cytokines in cardiac arrest.

Data Sources:

A PubMed literature review was performed for relevant articles. Only articles in English that studied cytokines in patients with cardiac arrest were included.

Results:

Cytokines play a crucial role in the pathogenesis of PCAS. Following cardiac arrest, the large release of circulating cytokines mediates the ischemia/reperfusion injury, brain dysfunction, and myocardial dysfunction seen. Interleukins, tumor necrosis factor, and matrix metalloproteinases all play a unique prognostic role in PCAS. High levels of inflammatory cytokines have been associated with mortality and/or poor neurologic outcomes. Interventions to modify the systemic inflammation seen in PCAS continue to be heavily studied. Currently, the only approved medical intervention for comatose patients following cardiac arrest is targeted temperature management. Medical agents, including minocycline and sodium sulfide, have demonstrated promise in animal models.

Conclusions:

The role of inflammatory cytokines for both short- and long-term outcomes is an important area for future investigation.

Intravenous hydrogen sulfide does not induce neuroprotection after aortic balloon occlusion-induced spinal cord ischemia/reperfusion injury in a human-like porcine model of ubiquitous arteriosclerosis

Objective

In rodents, intravenous sulfide protected against spinal cord ischemia/reperfusion (I/R) injury during aortic balloon occlusion. We investigated the effect of intravenous sulfide on aortic occlusion-induced porcine spinal cord I/R injury.

Methods

Anesthetized and mechanically ventilated “familial hypercholesterolemia Bretoncelles Meishan” (FBM) pigs with high-fat-diet-induced hypercholesterolemia and atherosclerosis were randomized to receive either intravenous sodium sulfide 2 h (initial bolus, 0.2 mg kg body weight (bw)⁻¹; infusion, 2 mg kg bw⁻¹ h⁻¹; n = 4) or vehicle (sodium chloride, n = 4) prior to 45 min of thoracic aortic balloon occlusion and for 8 h during reperfusion (infusion, 1 mg kg bw⁻¹ h⁻¹). During reperfusion, noradrenaline was titrated to maintain blood pressure at above 80% of the baseline level. Spinal cord function was assessed by motor evoked potentials (MEPs) and lower limb reflexes using a modified Tarlov score. Spinal cord tissue damage was evaluated in tissue collected at the end of experiment using hematoxylin and eosin and Nissl staining.

Results

A balloon occlusion time of 45 min resulted in marked ischemic neuron damage (mean of 16% damaged motoneurons in the anterior horn of all thoracic motor neurons) in the spinal cord. In the vehicle group, only one animal recovered partial neuronal function with regain of MEPs and link motions at each time point after deflating. All other animals completely lost neuronal functions. The intravenous application of sodium sulfide did not prevent neuronal cell injury and did not confer to functional recovery.

Conclusion

In a porcine model of I/R injury of the spinal cord, treatment with intravenous sodium sulfide had no protective effect in animals with a pre-existing arteriosclerosis.

Gas Signaling Molecules and Mitochondrial Potassium Channels

Recently, gaseous signaling molecules, such as carbon monoxide (CO), nitric oxide (NO), and hydrogen sulfide (H₂S), which were previously considered to be highly toxic, have been of increasing interest due to their beneficial effects at low concentrations. These so-called gasotransmitters affect many cellular processes, such as apoptosis, proliferation, cytoprotection, oxygen sensing, ATP synthesis, and cellular respiration. It is thought that mitochondria, specifically their respiratory complexes, constitute an important target for these gases. On the other hand, increasing evidence of a cytoprotective role for mitochondrial potassium channels provides motivation for the analysis of the role of gasotransmitters in the regulation of channel function. A number of potassium channels have been shown to exhibit activity within the inner mitochondrial membrane, including ATP-sensitive potassium channels, Ca²⁺-activated potassium channels, voltage-gated Kv potassium channels, and TWIK-related acid-sensitive K⁺ channel 3 (TASK-3). The effects of these channels include the regulation of mitochondrial respiration and membrane potential. Additionally, they may modulate the synthesis of reactive oxygen species within mitochondria. The opening of mitochondrial potassium channels is believed to induce cytoprotection, while channel inhibition may facilitate cell death. The molecular mechanisms underlying the action of gasotransmitters are complex. In this review, we focus on the molecular mechanisms underlying the action of H₂S, NO, and CO on potassium channels present within mitochondria.

The protective effects of total paeony glycoside on ischemia/reperfusion injury in H9C2 cells via inhibition of the PI3K/Akt signaling pathway

At present, cardiovascular disease is the global leading cause of mortality. Total paeony glycoside (TPG) is a traditional Chinese medicine, which serves a pivotal role in the cardiovascular system. In the present study, the effects and underlying mechanisms of TPG on ischemia/reperfusion (I/R) injury-induced apoptosis of cardiomyocytes were investigated in vitro. Cell Counting kit-8 and flow cytometry were used to assess the viability, reactive oxygen species (ROS) content and apoptosis of H9C2 cells. The activities of lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPX) were analyzed by commercial detection kits. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were conducted to evaluate the expression levels of various factors. The results demonstrated that the viability of H9C2 cells was not significantly altered in response to various concentrations of TPG. However, following I/R injury, TPG markedly enhanced cell viability in a time- and dose-dependent manner. Furthermore, TPG decreased the rate of apoptosis and ROS levels, and reduced the activities of MDA and LDH. Conversely, TPG increased SOD and GPX activities. In addition, TPG upregulated the expression levels of pro-caspase-3 and B-cell lymphoma2 (Bcl-2), whereas it downregulated cleaved-caspase-3, poly (ADP-ribose) polymerase 1, Bcl-2-associated X protein, phosphorylated (p)-phosphatidylinositol 3 kinase (PI3K) and p-protein kinase B (Akt) expression. Treatment with insulin-like growth factor-1 increased the apoptosis of H9C2 cells, thus suggesting that activation of the PI3K/Akt signaling pathway reversed the protective effects of TPG. Taken together, TPG may suppress I/R-induced apoptosis and oxidative stress of H9C2 cells possibly by inhibiting the PI3K/Akt signaling pathway; such a phenomenon may have a therapeutic effect on cardiovascular disease.

Definitions and pathophysiology of vasoplegic shock

Vasoplegia is the syndrome of pathological low systemic vascular resistance, the dominant clinical feature of which is reduced blood pressure in the presence of a normal or raised cardiac output. The vasoplegic syndrome is encountered in many clinical scenarios, including septic shock, post-cardiac bypass and after surgery, burns and trauma, but despite this, uniform clinical definitions are lacking, which renders translational research in this area challenging. We discuss the role of vasoplegia in these contexts and the criteria that are used to describe it are discussed. Intrinsic processes which may drive vasoplegia, such as nitric oxide, prostanoids, endothelin-1, hydrogen sulphide and reactive oxygen species production, are reviewed and potential for therapeutic intervention explored. Extrinsic drivers, including those mediated by glucocorticoid, catecholamine and vasopressin responsiveness of the blood vessels, are also discussed. The optimum balance between maintaining adequate systemic vascular resistance against the potentially deleterious effects of treatment with catecholamines is as yet unclear, but development of novel vasoactive agents may facilitate greater understanding of the role of the differing pathways in the development of vasoplegia. In turn, this may provide insights into the best way to care for patients with this common, multifactorial condition.

Hydrogen Sulfide: A Potential Novel Therapy for the Treatment of Ischemia

Hydrogen sulfide (H2S) is a novel signaling molecule most recently found to be of fundamental importance in cellular function as a regulator of apoptosis, inflammation, and perfusion. Mechanisms of endogenous H2S signaling are poorly understood; however, signal transmission is thought to occur via persulfidation at reactive cysteine residues on proteins. Although much has been discovered about how H2S is synthesized in the body, less is known about how it is metabolized. Recent studies have discovered a multitude of different targets for H2S therapy, including those related to protein modification, intracellular signaling, and ion channel depolarization. The most difficult part of studying hydrogen sulfide has been finding a way to accurately and reproducibly measure it. The purpose of this review is to: elaborate on the biosynthesis and catabolism of H2S in the human body, review current knowledge of the mechanisms of action of this gas in relation to ischemic injury, define strategies for physiological measurement of H2S in biological systems, and review potential novel therapies that use H2S for treatment.

Analysis of ischemic muscle in patients with peripheral artery disease using X-ray spectroscopy

BACKGROUND

Peripheral artery disease (PAD) is a vascular disease caused by atherosclerosis, resulting in decreased blood flow to the lower extremities. The ankle-brachial index (ABI) is a standard PAD diagnostic test but only identifies reduced blood flow based on blood pressure differences. The early signs of PAD manifest themselves not only at a clinical level but also at an elemental and biochemical level. However, the biochemical and elemental alterations to PAD muscle are not well understood. The objective of this study was to compare fundamental changes in intracellular elemental compositions between control, claudicating, and critical limb ischemia muscle tissue.

MATERIALS AND METHODS

Gastrocnemius biopsies from three subjects including one control (ABI ≥ 0.9), one claudicating (0.4 ≤ ABI < 0.9), and one critical limb ischemia patient (ABI < 0.4) were evaluated using a scanning electron microscope and energy dispersive X-ray spectroscopy to quantify differences in elemental compositions. Spectra were collected for five myofibers per specimen. An analysis of variance was performed to identify significant differences in muscle elemental compositions.

RESULTS

This study revealed that intracellular magnesium and calcium were lower in PAD compared with control myofibers, whereas sulfur was higher. Magnesium and calcium are antagonistic, meaning, if magnesium concentrations go down calcium concentrations should go up. However, our findings do not support this antagonism in PAD. Our analysis found decreases in sodium and potassium, in PAD myofibers.

CONCLUSIONS

These findings may provide insight into the pathologic mechanisms that may operate in ischemic muscle and aid in the development of specialized preventive and rehabilitative treatment plans for PAD patients.

Changes in hydrogen sulfide in rats with hepatic cirrhosis in different stages

This study aimed to observe changes in the hydrogen sulfide (H₂S) system in the blood and liver tissue of rats with hepatic cirrhosis at different stages by studying the effect of H₂S on the course of hyperdynamic circulation in rats with hepatic cirrhosis. H₂S concentration in the blood from the portal vein and inferior vena cava of hepatic cirrhosis rat model induced with carbon tetrachloride was detected on the 15th, 30th, and 52nd day. The expression of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) protein, and CBS and CSE mRNA in the liver was detected by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR), respectively. The results indicated that H₂S concentration in the blood from the portal vein and inferior vena cava of rats with hepatic cirrhosis was significantly lower than that in the control group. H₂S was gradually decreased with the development of the disease and significantly lower in the blood from portal vein than in the blood of inferior vena cava at the mid-stage and the late stage groups. The expression levels of CBS and CSE protein, and CBS and CSE mRNA in the livers with hepatic cirrhosis at different stages were all higher than those in the control group, and the expression gradually increased with the development of the disease. The expression of CBS was lower than CSE in the same stages. The results indicated that the CSE mRNA was expressed predominantly in the cirrhosis groups as compared with CBS mRNA. Among experimental rats, the H₂S system has an important effect on the occurrence and development of hyperdynamic circulation in rats with hepatic cirrhosis. This finding adds to the literature by demonstrating that H₂S protects vascular remodelling in the liver, and that CSE is indispensable in this process.

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.

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.

Hydrogen Sulfide Improves Cardiomyocyte Function in a Cardiac Arrest Model

Background

Cardioplegic arrest is a common procedure for many types of cardiac surgery, and different formulations have been proposed to enhance its cardio-protective effect. Hydrogen sulfide is an important signaling molecule that has cardio-protective properties. We therefore studied the cardio-protective effect of hydrogen sulfide in cardiac cell culture and its potential therapeutic use in combination with cardioplegia formulations.

Materials/Methods

We added hydrogen sulfide donor GYY4137 to HL-1 cells to study its protective effect in nutrient starved conditions. In addition, we tested the potential use of GYY4137 when it is added into two different cardioplegia formulations: Cardi-Braun^® solution and del Nido solution in an ex vivo Langendorff perfused rat hearts model.

Results

We observed that eight-hour pre-treatment with GYY4137 significantly suppressed apoptosis in nutrient-starved HL-1 cells (28% less compared to untreated cells; p<0.05), maintained ATP content, and reduced protein synthesis. In ex vivo experiments, Cardi-Braun^® and del Nido cardioplegia solutions supplemented with GYY4137 significantly reduced the pro-apoptotic protein caspase-3 content and preserved ATP content. Furthermore, GYY4137 supplemented cardioplegia solutions decreased the S-(5-adenosyl)-L-methionine/S-(adenosyl)-L-homocysteine ratio, reducing the oxidative stress in cardiac tissue. Finally, heart beating analysis revealed the preservation of the inter-beat interval and the heart rate in del Nido cardioplegia solution supplemented with GYY4137.

Conclusions

GYY4137 preconditioning preserved energetic state during starved conditions, attenuating the cardiomyocytes apoptosis in vitro. The addition of GYY4137 to cardioplegia solutions prevented apoptosis, ATP consumption, and oxidative stress in perfused rat hearts, restoring its electrophysiological status after cardiac arrest. These findings suggested that GYY4137 sulfide donor may improve the cardioplegia solution performance during cardiac surgery.

Sevoflurane postconditioning protects the myocardium against ischemia/reperfusion injury via activation of the JAK2-STAT3 pathway

BACKGROUND

Sevoflurane postconditioning (S-post) has similar cardioprotective effects as ischemic preconditioning. However, the underlying mechanism of S-post has not been fully elucidated. Janus kinase signaling transduction/transcription activator (JAK2-STAT3) plays an important role in cardioprotection. The purpose of this study was to determine whether the cardioprotective effects of S-post are associated with activation of the JAK2-STAT3 signal pathway.

METHODS

An adult male Sprague-Dawley (SD) rat model of myocardial ischemia/reperfusion (I/R) injury was established using the Langendorff isolated heart perfusion apparatus. At the beginning of reperfusion, 2.4% sevoflurane alone or in combination with AG490 (a JAK2 selective inhibitor) was used as a postconditioning treatment. The cardiac function indicators, myocardial infarct size, lactic dehydrogenase (LDH) release, mitochondrial ultrastructure, mitochondrial reactive oxygen species (ROS) generation rates, ATP content, protein expression of p-JAK, p-STAT3, Bcl-2 and Bax were measured.

RESULTS

Compared with the I/R group, S-post significantly increased the expression of p-JAK, p-STAT3 and Bcl-2 and reduced the protein expression of Bax, which markedly decreased the myocardial infarction areas, improved the cardiac function indicators and the mitochondrial ultrastructure, decreased the mitochondrial ROS and increased the ATP content. However, the cardioprotective effects of S-post were abolished by treatment with a JAK2 selective inhibitor (p < 0.05).

CONCLUSION

This study demonstrates that the cardioprotective effects of S-post are associated with the activation of JAK2-STAT3. The mechanism may be related to an increased expression of p-JAK2 and p-STAT3 after S-post, which reduced mitochondrial ROS generation and increased mitochondrial ATP content, thereby reducing apoptosis and myocardial infarct size.

Hydrogen Sulfide Reduces Recruitment of CD11b+Gr-1+ Cells in Mice With Myocardial Infarction

The present study aimed to elucidate the mechanisms by which hydrogen sulfide (H2S) attenuates left ventricular remodeling after myocardial infarction (MI). MI was created in mice by left coronary artery ligation. One group of mice received injections of the H2S donor sodium hydrosulfide (NaHS) immediately before and 1 h after ligation, while the control group received saline alone. During both the subacute and chronic stages (1 and 4 weeks postinfarction, respectively), NaHS-treated mice demonstrated attenuation of cardiac dilation in the infarcted myocardium. Furthermore, fewer CD11b+Gr-1+ myeloid cells were detected in the infarct myocardium and peripheral blood from NaHS-treated mice, while more CD11b+Gr-1+ cells remained in the spleen and bone marrow in these animals. NaHS-treated mice also exhibited reduction in cardiomyocyte apoptosis, interstitial fibrosis, cardiac hypertrophy, and pulmonary edema, as well as overall better survival rates, when compared to controls. Thus, exogenous H2S has favorable effects on cardiac remodeling after MI. These observations further support the emerging concept that H2S treatment might have therapeutic benefits in the setting of ischemia-induced heart failure.

Hydrogen sulfide alleviates uranium-induced acute hepatotoxicity in rats: Role of antioxidant and antiapoptotic signaling

As an endogenous gaseous mediator, H₂ S exerts antioxidative, antiapoptotic, and cytoprotective effects in livers. This study was designed to investigate the protective role of H₂ S against uranium-induced hepatotoxicity in adult SD male rats after in vivo effect of uranium on endogenous H₂ S production was determined in livers. The levels of endogenous H₂ S and H₂ S-producing enzymes (CBS and CSE) were measured in liver homogenates from uranium -intoxicated rats. In rats injected intraperitoneally (i.p.) with uranyl acetate or NaHS (an H₂ S donor) alone or in combination, we examined biochemical parameters to assess liver function, revealed hepatic histopathological alteration, investigated oxidative stress markers, and explored apoptotic signaling in liver homogenates. The results suggest that uranium-intoxication in rats decreased CBS and CSE protein expression, H₂ S synthesis capacity, and endogenous H₂ S generation. NaHS administration in uranium-intoxicated rats produced amelioration in liver biochemical indices and histopathological effects, decreased MDA content, and increased GSH level and antioxidative enzymes activities like SOD, CAT, GPx, and GST. NaHS administration in uranium-intoxicated rats attenuated uranium-activated phosphorylation state of JNK. NaHS treatment in uranium-intoxicated rats increased antiapoptotic Bcl-2 but decreased pro-apoptotic Bax, resulting in the rise of Bcl-2/Bax ratio. NaHS treatment in uranium-intoxicated rats reduced the apoptosis mediator caspase-3 and cytochrome c release and elevated ATP contents. Taken together, these data implicate that H₂ S can afford protection to rat livers against uranium-induced adverse effects mediated by up-regulation of antioxidant and antiapoptotic signaling. The anti-apoptotic property of H₂ S may be involved, at least in part, in inhibiting JNK signaling. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 581-593, 2017.

Hypometabolism as the ultimate defence in stress response: how the comparative approach helps understanding of medically relevant questions

First conceptualized from breath-hold diving mammals, later recognized as the ultimate cell autonomous survival strategy in anoxia-tolerant vertebrates and burrowing or hibernating rodents, hypometabolism is typically recruited by resilient organisms to withstand and recover from otherwise life-threatening hazards. Through the coordinated down-regulation of biosynthetic, proliferative and electrogenic expenditures at times when little ATP can be generated, a metabolism turned 'down to the pilot light' allows the re-balancing of energy demand with supply at a greatly suppressed level in response to noxious exogenous stimuli or seasonal endogenous cues. A unifying hallmark of stress-tolerant organisms, the adaptation effectively prevents lethal depletion of ATP, thus delineating a marked contrast with susceptible species. Along with disengaged macromolecular syntheses, attenuated transmembrane ion shuttling and PO₂ -conforming respiration rates, the metabolic slowdown in tolerant species usually culminates in a non-cycling, quiescent phenotype. However, such a reprogramming also occurs in leading human pathophysiologies. Ranging from microbial infections through ischaemia-driven infarcts to solid malignancies, cells involved in these disorders may again invoke hypometabolism to endure conditions non-permissive for growth. At the same time, their reduced activities underlie the frequent development of a general resistance to therapeutic interventions. On the other hand, a controlled induction of hypometabolic and/or hypothermic states by pharmacological means has recently stimulated intense research aimed at improved organ preservation and patient survival in situations requiring acutely administered critical care. The current review article therefore presents an up-to-date survey of concepts and applications of a coordinated and reversibly down-regulated metabolic rate as the ultimate defence in stress responses.

Delivery of Hydrogen Sulfide by Ultrasound Targeted Microbubble Destruction Attenuates Myocardial Ischemia-reperfusion Injury

Hydrogen sulfide (H₂S) is an attractive agent for myocardial ischemia-reperfusion injury, however, systemic delivery of H₂S may cause unwanted side effects. Ultrasound targeted microbubble destruction has become a promising tool for organ specific delivery of bioactive substance. We hypothesized that delivery of H₂S by ultrasound targeted microbubble destruction attenuates myocardial ischemia-reperfusion injury and could avoid unwanted side effects. We prepared microbubbles carrying hydrogen sulfide (hs-MB) with different H₂S/C₃F₈ ratios (4/0, 3/1, 2/2, 1/3, 0/4) and determined the optimal ratio. Release of H₂S triggered by ultrasound was investigated. The cardioprotective effect of ultrasound targeted hs-MB destruction was investigated in a rodent model of myocardial ischemia-reperfusion injury. The H₂S/C₃F₈ ratio of 2/2 was found to be an optimal ratio to prepare stable hs-MB with higher H₂S loading capability. Ultrasound targeted hs-MB destruction triggered H₂S release and increased the concentration of H₂S in the myocardium and lung. Ultrasound targeted hs-MB destruction limited myocardial infarct size, preserved left ventricular function and had no influence on haemodynamics and respiratory. This cardioprotective effect was associated with alleviation of apoptosis and oxidative stress. Delivery of H₂S to the myocardium by ultrasound targeted hs-MB destruction attenuates myocardial ischemia-reperfusion injury and may avoid unwanted side effects.

Ratiometric QD-FRET Sensing of Aqueous H2S in Vitro

We report a platform for the ratiometric fluorescent sensing of endogenously generated gaseous transmitter H2S in its aqueous form (bisulfide or hydrogen sulfide anion) based on the alteration of Förster resonance energy transfer from an emissive semiconductor quantum dot (QD) donor to a dithiol-linked organic dye acceptor. The disulfide bridge between the two chromophores is cleaved upon exposure to bisulfide, resulting in termination of FRET as the dye diffuses away from the QD. This results in enhanced QD emission and dye quenching. The resulting ratiometric response can be correlated quantitatively to the concentration of bisulfide and was found to have a detection limit as low as 1.36 ± 0.03 μM. The potential for use in biological applications was demonstrated by measuring the response of the QD-based FRET sensor microinjected into live HeLa cells upon extracellular exposure to bisulfide. The methodology used here is built upon a highly multifunctional platform that offers numerous advantages, such as low detection limit, enhanced photochemical stability, and sensing ability within a biological milieu.

Hydrosulfide attenuates acute myocardial ischemic injury through the glycogen synthase kinase-3β/β-catenin signaling pathway

The endogenous signaling gasotransmitter, hydrosulfide (H2S), has been shown to exert cardioprotective effects against acute myocardial infarction (AMI) due to ischemic injury. However, the mechanisms responsible for these effects are not yet fully understood. In this study, we investigated whether sodium hydrogen sulfide (NaHS), an H2S donor, attenuates acute myocardial ischemic injury through glycogen synthase kinase-3β (GSK-3β)/β-catenin signaling. For this purpose, we utilized an in vivo rat model of AMI by occluding the left anterior descending coronary artery. NaHS (0.39, 0.78 or 1.56 mg/kg, intraperitoneally), the GSK-3β inhibitor, SB216763 (0.6 mg/kg, intravenously), or 1% dimethylsulfoxide (2 ml/kg, intravenously) were administered to the rats. The results demonstrated that the administration of medium- and high-dose NaHS and SB216763 significantly improved rat cardiac function, as evidenced by an increase in the mean arterial pressure, left ventricular developed pressure, contraction and relaxation rates, as well as a decrease in left ventricular end-diastolic pressure. In addition, the administration of NaHS and SB216763 attenuated myocardial injury as reflected by a decrease in apoptotic cell death and in the serum lactate dehydrogenase concentrations, and prevented myocardial structural changes. The administration of NaHS and SB216763 increased the concentrations of phosphorylated (p-)GSK-3β, the p-GSK-3β/t-GSK-3β ratio and downstream protein β-catenin. Moreover, western blot and immunohistochemical analyses of apoptotic signaling pathway proteins further established the cardioprotective potential of NaHS, as reflected by the upregulation of Bcl-2 expression, the downregulation of Bax expression, and a decrease in the number of TUNEL-positive stained cells. These findings suggest that hydrosulfide exerts cardioprotective effects against AMI-induced apoptosis through the GSK-3β/β-catenin signaling pathway.

Antiapoptotic Effect of Recombinant HMGB1 A-box Protein via Regulation of microRNA-21 in Myocardial Ischemia-Reperfusion Injury Model in Rats

The ~80 amino acid A box DNA-binding domain of high mobility group box 1 (HMGB1) protein antagonizes proinflammatory responses during myocardial ischemia reperfusion (I/R) injury. The exact role of microRNA-21 (miR-21) is unknown, but its altered levels are evident in I/R injury. This study examined the roles of HMGB1 A-box and miR-21 in rat myocardial I/R injury model. Sixty Sprague-Dawley rats were randomly divided into six equal groups: (1) Sham; (2) I/R; (3) Ischemic postconditioning (IPost); (4) AntagomiR-21 post-treatment; (5) Recombinant HMGB1 A-box pretreatment; and (6) Recombinant HMGB1 A-box + antagomiR-21 post-treatment. Hemodynamic indexes, arrhythmia scores, ischemic area and infarct size, myocardial injury, and related parameters were studied. Expression of miR-21 was detected by real-time quantitative polymerase chain reaction (qRT-PCR) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to quantify apoptosis. Left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), maximal rate of pressure rise (+dp/dtmax), and decline (-dp/dtmax) showed clear reduction upon treatment with recombinant HMGB1 A-box. Arrhythmia was relieved and infarct area decreased in the group pretreated with recombinant HMGB1 A-box, compared with other groups. Circulating lactate dehydrogenase (LDH) and malondialdehyde (MDA) levels increased in response to irreversible cellular injury, while creatine kinase MB isoenzymes (CK-MB) and superoxide dismutase (SOD) activities were reduced in the I/R group, which was reversed following recombinant HMGB1 A-box treatment. Interestingly, pretreatment with recombinant HMGB1 A-box showed the most dramatic reductions in miR-21 levels, compared with other groups. Significantly reduced apoptotic index (AI) was seen in recombinant HMGB1 A-box pretreatment group and recombinant HMGB1 A-box + antagomiR-21 post-treatment group, with the former showing a more dramatic lowering in AI than the latter. Bax, caspase-8, and CHOP showed reduced expression, and Bcl-2 and p-AKT levels were upregulated in recombinant HMGB1 A-box pretreatment group. Thus, recombinant HMGB1 A-box treatment protects against I/R injury and the mechanisms may involve inhibition of miR-21 expression.

Hydrogen sulfide: physiological properties and therapeutic potential in ischaemia

Hydrogen sulfide (H2 S) has become a molecule of high interest in recent years, and it is now recognized as the third gasotransmitter in addition to nitric oxide and carbon monoxide. In this review, we discuss the recent literature on the physiology of endogenous and exogenous H2 S, focusing upon the protective effects of hydrogen sulfide in models of hypoxia and ischaemia.

Hydrogen sulfide attenuates doxorubicin-induced cardiotoxicity by inhibiting the expression of peroxiredoxin III in H9c2 cells

Doxorubicin (DOX) is a widely used chemotherapeutic agent, which can give rise to severe cardiotoxicity, limiting its clinical use. Preliminary evidence suggests that hydrogen sulfide (H2S) may exert protective effects on DOX‑induced cardiotoxicity. Therefore, the aim of the present study was to investigate whether peroxiredoxin III is involved in the cardioprotection of H2S against DOX‑induced cardiotoxicity. The results demonstrated that DOX not only markedly induced injuries, including cytotoxicity and apoptosis, it also increased the expression levels of peroxiredoxin III. Notably, pretreatment with sodium hydrosulfide significantly attenuated the DOX‑induced decrease in cell viability and increase in apoptosis, and also reversed the increased expression levels of peroxiredoxin III in H9c2 cardiomyocytes. In addition, pretreatment of the H9c2 cells with N‑acetyl‑L‑cysteine, a scavenger of reactive oxygen species, prior to exposure to DOX markedly decreased the expression levels of peroxiredoxin III. In conclusion, the results of the present study suggested that exogenous H2S attenuates DOX‑induced cardiotoxicity by inhibiting the expression of peroxiredoxin III in H9c2 cells. In the present study, the apoptosis of H9c2 cardiomyocytes was assessed using an methyl thiazolyl tetrazolium assay and Hoechst staining. The levels of Prx III and cystathionine-γ-lyase were examined by western blotting.

Selenide Targets to Reperfusing Tissue and Protects It From Injury

OBJECTIVES

Since blood selenium levels decrease after ischemia and reperfusion injury, and low blood selenium correlates with negative outcome, we designed and performed experiments to determine how selenium distribution is affected by ischemia reperfusion injury. Furthermore, we tested whether different chemical forms of selenium would affect outcome after ischemia and reperfusion injury. We also examined the metabolic effects of selenide administration.

DESIGN

Laboratory investigation.

SETTING

Animal research laboratory.

SUBJECTS

Adult male C57BL/6 mice.

INTERVENTIONS

To determine selenium localization, we administered tracer doses of radioactive selenium 75 in the form of selenite or selenide and measured blood and tissue selenium levels after ischemia and reperfusion injury. Anesthetized mice were subjected to myocardial ischemia reperfusion injury (coronary artery occlusion for 60 min followed by 5 min of reperfusion after occlusion was removed) or hindlimb ischemia reperfusion injury (left leg tourniquet for 90 min followed by 5 min reperfusion after tourniquet removal). To determine whether exogenous selenium administration could reduce ischemia reperfusion injury, we synthesized and administered sodium hydroselenide and sodium selenite solutions (0.05-2.4 mg/kg). Solutions were administered at the end of coronary artery occlusion but before reperfusion. In order to determine the metabolic effects of selenide administration, we exposed mice to hydrogen selenide gas (0-5 ppm) mixed into air (20.95% oxygen) for up to 3 hours.

MEASUREMENTS AND MAIN RESULTS

In targeting assays, we measured blood and tissue selenium levels. We observed that blood selenium decreases after myocardial ischemia reperfusion and displays an inverse correlation with injury severity; selenium accumulation in heart correlates directly with injury severity. We also measured whether oxidized selenium, selenite, and reduced selenium, selenide, would target to injured heart tissue in myocardial ischemia reperfusion and injured leg muscle in a hindlimb model of ischemia reperfusion. Only selenide targets to injured tissue. We also measured damage after myocardial ischemia reperfusion injury using morphometry, neutrophil accumulation, blood cardiac troponin levels, and echocardiography and observed in all assays that selenide reduced damage to the heart; selenite was not effective. And finally, to assay metabolism, we measured oxygen consumption, carbon dioxide production, and body core temperature before, during, and after hydrogen selenide administration. All measurements indicate that selenide decreases metabolism.

CONCLUSIONS

Selenide targets to reperfusing tissue and reduces reperfusion injury perhaps by affecting oxygen metabolism.