Hydrogen sulfide ameliorates rat myocardial fibrosis induced by thyroxine through PI3K/AKT signaling pathway

The interplay of hydrogen sulfide and microRNAs in cardiovascular diseases: insights and future perspectives

Hydrogen sulfide (H2S) is recognized as the third gasotransmitter, after nitric oxide (NO) and carbon monoxide (CO). It is known for its cardioprotective properties, including the relaxation of blood vessels, promotion of angiogenesis, regulation of myocardial cell apoptosis, inhibition of vascular smooth muscle cell proliferation, and reduction of inflammation. Additionally, abnormal H2S generation has been linked to the development of cardiovascular diseases (CVD), such as pulmonary hypertension, hypertension, atherosclerosis, vascular calcification, and myocardial injury. MicroRNAs (miRNAs) are non-coding, conserved, and versatile molecules that primarily influence gene expression by repressing translation and have emerged as biomarkers for CVD diagnosis. Studies have demonstrated that H2S can ameliorate cardiac dysfunction by regulating specific miRNAs, and certain miRNAs can also regulate H2S synthesis. The crosstalk between miRNAs and H2S offers a novel perspective for investigating the pathophysiology, prevention, and treatment of CVD. The present analysis outlines the interactions between H2S and miRNAs and their influence on CVD, providing insights into their future potential and advancement.

Crosstalk among Reactive Oxygen Species, Autophagy and Metabolism in Myocardial Ischemia and Reperfusion Stages

Myocardial ischemia is the most common cardiovascular disease. Reperfusion, an important myocardial ischemia tool, causes unexpected and irreversible damage to cardiomyocytes, resulting in myocardial ischemia/reperfusion (MI/R) injury. Upon stress, especially oxidative stress induced by reactive oxygen species (ROS), autophagy, which degrades the intracellular energy storage to produce metabolites that are recycled into metabolic pathways to buffer metabolic stress, is initiated during myocardial ischemia and MI/R injury. Excellent cardioprotective effects of autophagy regulators against MI and MI/R have been reported. Reversing disordered cardiac metabolism induced by ROS also exhibits cardioprotective action in patients with myocardial ischemia. Herein, we review current knowledge on the crosstalk between ROS, cardiac autophagy, and metabolism in myocardial ischemia and MI/R. Finally, we discuss the possible regulators of autophagy and metabolism that can be exploited to harness the therapeutic potential of cardiac metabolism and autophagy in the diagnosis and treatment of myocardial ischemia and MI/R.

Elucidating the Molecular Pathways and Therapeutic Interventions of Gaseous Mediators in the Context of Fibrosis

Fibrosis, a pathological alteration of the repair response, involves continuous organ damage, scar formation, and eventual functional failure in various chronic inflammatory disorders. Unfortunately, clinical practice offers limited treatment strategies, leading to high mortality rates in chronic diseases. As part of investigations into gaseous mediators, or gasotransmitters, including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), numerous studies have confirmed their beneficial roles in attenuating fibrosis. Their therapeutic mechanisms, which involve inhibiting oxidative stress, inflammation, apoptosis, and proliferation, have been increasingly elucidated. Additionally, novel gasotransmitters like hydrogen (H2) and sulfur dioxide (SO2) have emerged as promising options for fibrosis treatment. In this review, we primarily demonstrate and summarize the protective and therapeutic effects of gaseous mediators in the process of fibrosis, with a focus on elucidating the underlying molecular mechanisms involved in combating fibrosis.

Mechanisms Underlying the Hydrogen Sulfide Actions: Target Molecules and Downstream Signaling Pathways

Significance: As a new important gas signaling molecule like nitric oxide (NO) and carbon dioxide (CO), hydrogen sulfide (H2S), which can be produced by endogenous H2S-producing enzymes through l-cysteine metabolism in mammalian cells, has attracted wide attention for long. H2S has been proved to play an important regulatory role in numerous physiological and pathophysiological processes. However, the deep mechanisms of those different functions of H2S still remain uncertain. A better understanding of the mechanisms can help us develop novel therapeutic strategies. Recent Advances: H2S can play a regulating role through various mechanisms, such as regulating epigenetic modification, protein expression levels, protein activity, protein localization, redox microenvironment, and interaction with other gas signaling molecules such as NO and CO. In addition to discussing the molecular mechanisms of H2S from the above perspectives, this article will review the regulation of H2S on common signaling pathways in the cells, including the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), mitogen-activated protein kinase (MAPK), Janus kinase (JAK)/signal transducer, and activator of transcription (STAT) signaling pathway. Critical Issues: Although there are many studies on the mechanism of H2S, little is known about its direct target molecules. This article will also review the existing reports about them. Furthermore, the interaction between direct target molecules of H2S and the downstream signaling pathways involved also needs to be clarified. Future Directions: An in-depth discussion of the mechanism of H2S and the direct target molecules will help us achieving a deeper understanding of the physiological and pathophysiological processes regulated by H2S, and lay a foundation for developing new clinical therapeutic drugs in the future. Innovation: This review focuses on the regulation of H2S on signaling pathways and the direct target molecules of H2S. We also provide details on the underlying mechanisms of H2S functions from the following aspects: epigenetic modification, regulation of protein expression levels, protein activity, protein localization, redox microenvironment, and interaction with other gas signaling molecules such as NO and CO. Further study of the mechanisms underlying H2S will help us better understand the physiological and pathophysiological processes it regulates, and help develop new clinical therapeutic drugs in the future. Antioxid. Redox Signal. 40, 86-109.

AP39 inhibits ferroptosis by inhibiting mitochondrial autophagy through the PINK1/parkin pathway to improve myocardial fibrosis with myocardial infarction

BACKGROUND AND PURPOSE

Research has revealed the involvement of mitochondrial autophagy and iron death in the pathogenesis of myocardial fibrosis. The objective of this study is to investigate whether the mitochondrial-targeted H2S donor AP39 inhibits mitochondrial autophagy and antagonizes myocardial cell iron death through the PINK1/Parkin pathway, thereby improving myocardial fibrosis in rats with myocardial infarction.

EXPERIMENTAL APPROACH

A rat model of myocardial infarction was created by intraperitoneal injection of a high dose of isoproterenol, and H9c2 myocardial cells were subjected to hypoxic injury induced by CoCl2. Western blot, RT-PCR, transmission electron microscopy, immunohistochemistry, as well as echocardiography, and studies on isolated hearts were employed.

KEY RESULTS

In the hearts of rats with myocardial infarction, there was a significant accumulation of interstitial collagen fibers, accompanied by downregulation of CSE protein expression, activation of the PINK1/Parkin signaling pathway, and activation of mitochondrial autophagy. Intervention with AP39 resulted in a significant improvement of the aforementioned changes, which could be reversed by the addition of PAG. Similar results were observed in vitro experiments. Furthermore, the addition of CCCP reversed the antagonistic effect of AP39 on myocardial cell iron death, while the addition of RSL3 reversed the inhibitory effect of AP39 on collagen production in myocardial cells.

CONCLUSION AND IMPLICATIONS

The mitochondrial-targeted H2S donor AP39 can inhibit mitochondrial autophagy through the PINK1/Parkin pathway, antagonize myocardial cell iron death, and improve myocardial fibrosis in rats with myocardial infarction.

Vascular smooth muscle cell-derived hydrogen sulfide promotes atherosclerotic plaque stability via TFEB (transcription factor EB)-mediated autophagy

Vascular smooth muscle cells (VSMCs) contribute to plaque stability. VSMCs are also a major source of CTH (cystathionine gamma-lyase)-hydrogen sulfide (H₂S), a protective gasotransmitter in atherosclerosis. However, the role of VSMC endogenous CTH-H₂S in pathogenesis of plaque stability and the mechanism are unknown. In human carotid plaques, CTH expression in ACTA2⁺ cells was dramatically downregulated in lesion areas in comparison to non-lesion areas. Intraplaque CTH expression was positively correlated with collagen content, whereas there was a negative correlation with CD68⁺ and necrotic core area, resulting in a rigorous correlation with vulnerability index (r = -0.9033). Deletion of Cth in VSMCs exacerbated plaque vulnerability, and were associated with VSMC autophagy decline, all of which were rescued by H₂S donor. In ox-LDL treated VSMCs, cth deletion reduced collagen and heightened apoptosis association with autophagy reduction, and vice versa. For the mechanism, CTH-H₂S mediated VSMC autophagosome formation, autolysosome formation and lysosome function, in part by activation of TFEB, a master regulator for autophagy. Interference with TFEB blocked CTH-H₂S effects on VSMCs collagen and apoptosis. Next, we demonstrated that CTH-H₂S sulfhydrated TFEB at Cys212 site, facilitating its nuclear translocation, and then promoting transcription of its target genes such as ATG9A, LAPTM5 or LDLRAP1. Conclusively, CTH-H₂S increases VSMC autophagy by sulfhydration and activation of TFEB, promotes collagen secretion and inhibits apoptosis, thereby attenuating atherogenesis and plaque vulnerability. CTH-H₂S may act as a warning biomarker for vulnerable plaque.Abbreviations ATG9A: autophagy related 9A; CTH: cystathionine gamma-lyase; CQ: chloroquine; HASMCs: human aortic smooth muscle cells; H₂S: hydrogen sulfide; LAMP1: lysosomal associated membrane protein 1; LAPTM5: lysosomal protein transmembrane 5; NaHS: sodium hydrosulfide hydrate; ox-LDL: oxidized-low density lipoprotein; PPG: DL- propagylglycine; TFEB: transcription factor EB; 3-MA: 3-methyladenine; VSMCs: vascular smooth muscle cells.

N-Acetylcysteine, an ROS Inhibitor, Alleviates the Pathophysiology of Hyperthyroidism-Induced Cardiomyopathy via the ROS/Ca2+ Pathway

Hyperthyroidism is common and can induce cardiomyopathy, but there is no effective therapeutic strategy. The purpose of this study was to investigate the molecular mechanism of hyperthyroidism-induced cardiomyopathy (HTC) and the effect of N-acetylcysteine (NAC), an ROS inhibitor, on the pathophysiology of HTC in vivo and in vitro. Compared with those in the control groups in vivo and in vitro, TT3 and TT4 were significantly increased, the structure of myocardial cells was enlarged and disordered, and interstitial fibrosis and the apoptosis of myocardial cells were markedly increased in the L-Thy group. The ROS and inflammatory response were increased in the hyperthyroidism group. In the NAC group, the contents of TT3 and TT4 were decreased, the myocardial cell structure was slightly disturbed, fibrosis and apoptosis were significantly reduced, and the ROS level and inflammatory response were significantly reduced. Interestingly, L-Thy decreased the viability of fibroblasts and H9c2 cells, suggesting that L-Thy-induced fibrosis was not caused by the proliferation of fibroblasts. The molecular mechanism of HTC could be explained by the fact that L-Thy could cause cardiac hypertrophy, inflammation, and fibrosis by regulating the Ca2+/calpain/Rcan1-dependent signalling pathway, the Ca2+/Rcan1/NF-κB/p65-dependent signalling pathway, and the Ca2+/ROS/Bcl-2/caspase-3-dependent signalling pathway. In conclusion, NAC can alleviate the pathophysiology of hyperthyroidism-induced cardiomyopathy, probably by regulating the ROS/Ca2+-dependent pathway.

Whole-Blood MicroRNA Sequence Profiling and Identification of Specific miR-21 for Adolescents With Postural Tachycardia Syndrome

Objective

The aim of the study was to establish whether whole-blood microRNA (miRNA) profiles differ between postural tachycardia syndrome (POTS) sufferers and control subjects and to identify the miRNA that regulates plasma H₂S.

Study Design

High-throughput sequencing was used to obtain whole-blood miRNA expression profiles for 20 POTS sufferers and 20 normal children.The thresholds for defining differentially expressed miRNAs (DEmiRNAs) were an adjusted DESeq P of <0.05 and a log2 fold variation of ≥3. The DEmiRNA target genes were identified using RNAhybrid and miRanda, and only those identified by both were considered. The combined effects of the DEmiRNAs were determined using KEGG pathway analysis. Another 40 POTS and 20 normal patients were used as validation subjects. Plasma H₂S was determined with a sulfide electrode, and flow-mediated vasodilation (FMD) was performed with a color Doppler ultrasound system. miRNAs were analyzed using qRT-PCR.

Results

Totally, 13 DEmiRNAs were identified through high-throughput sequencing. In the 60-member validation group, the 13 miRNAs were verified again, and it turned out that miR-21 was significantly elevated and could diagnose POTS with a 100% specificity and 92.5% sensitivity. Overall, 198 and 481 genes, respectively, were shown to be targeted by the 13 DEmiRNAs when P values of 0.01 and 0.05 were used. The target gene of hsa-miR-21-5p was SP1 when the P-value is <0.01. DEmiRNAs were significantly enriched in 36 pathways (P < 0.05), in which PI3K/Akt signaling was closely related to vascular function. In the validation subjects, the plasma H₂S and FMD were higher in the POTS sufferers (P < 0.05).

Conclusion

Elevated whole-blood miR-21 levels serve as an indicator for POTS and may explain the increased plasma H₂S observed in POTS sufferers.

MicroRNA-34a: A Novel Therapeutic Target in Fibrosis

Fibrosis can occur in many organs, and severe cases leading to organ failure and death. No specific treatment for fibrosis so far. In recent years, microRNA-34a (miR-34a) has been found to play a role in fibrotic diseases. MiR-34a is involved in the apoptosis, autophagy and cellular senescence, also regulates TGF-β1/Smad signal pathway, and negatively regulates the expression of multiple target genes to affect the deposition of extracellular matrix and regulate the process of fibrosis. Some studies have explored the efficacy of miR-34a-targeted therapies for fibrotic diseases. Therefore, miR-34a has specific potential for the treatment of fibrosis. This article reviews the important roles of miR-34a in fibrosis and provides the possibility for miR-34a as a novel therapeutic target in fibrosis.

Interplay between PI3K/AKT pathway and heart disorders

The PI3K/AKT signaling has crucial role in the regulation of numerous physiological functions through activation of downstream effectors and modulation of cell cycle transition, growth and proliferation. This pathway participates in the pathogenesis of several human disorders such as heart diseases through regulation of size and survival of cardiomyocytes, angiogenic processes as well as inflammatory responses. Moreover, PI3K/AKT pathway participates in the process of myocardial injury induced by a number of substances such as H₂O₂, Mercury, lipopolysaccharides, adriamycin, doxorubicin and epirubicin. In this review, we describe the contribution of this pathway in the pathoetiology of myocardial ischemia/reperfusion injury and myocardial infarction, heart failure, cardiac hypertrophy, cardiomyopathy and toxins-induced cardiac injury.

Hydrogen sulfide regulates autophagy in nucleus pulposus cells under hypoxia

OBJECTIVE

Hydrogen sulfide (H2S) has been found to act as an important gasotransmitter to regulate cell activities. This study aimed to investigate the effect of H2S on autophagy of nucleus pulposus (NP) cells under hypoxia and possible mechanism.

MATERIALS AND METHODS

NP cells were isolated from rat caudal discs. Cobalt chloride was used to mimic hypoxia, sodium hydrosulfide was used to emulate exogenous H2S and 3-methyladenine was used to block cell autophagy. Cell viability was assessed by phase contrast microscope and Cell Counting Kit-8 method. Moreover, expression of key autophagic proteins was analyzed via western blotting, and transmission electron microscopy was performed to detect autophagosomes.

RESULTS

Hypoxia markedly impaired NP cell proliferation compared with control. Whereas H2S provided pro-proliferation and pro-autophagy effects on hypoxic NP cells. However, these beneficial impact of H2S on hypoxic NP cells were reversed by autophagy inhibitor.

CONCLUSIONS

Our results showed that H2S played a cytoprotective role in NP cells exposed to hypoxia in an autophagy-dependent manner.

miR‑214 ameliorates sepsis‑induced acute kidney injury via PTEN/AKT/mTOR‑regulated autophagy

Previous studies have suggested that oxidative stress and autophagy results in acute kidney injury (AKI) during sepsis and microRNA (miR)-214 serves a vital role in the protection of kidneys subjected to oxidative stress. The present study aimed to test whether the renoprotection of miR-214 is related to autophagy in sepsis. The role of autophagy was investigated in a mouse model of cecal ligation and puncture (CLP). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to analyze the expression of miR-214. The structure and function of kidneys harvested from the mice were evaluated. Kidney autophagy levels were detected with immunohistochemical, immunofluorescent and western blotting. It was found that miR-214 could alleviate AKI in septic mice by inhibiting the level of kidney autophagy. Furthermore, miR-214 inhibited autophagy by silencing PTEN expression in the kidney tissues of septic mice. These findings indicated that miR-214 ameliorated CLP-induced AKI by reducing oxidative stress and inhibiting autophagy through the regulation of the PTEN/AKT/mTOR pathway.

EndMT: Potential Target of H2S against Atherosclerosis

Atherosclerosis is a chronic arterial wall illness that forms atherosclerotic plaques within the arteries. Plaque formation and endothelial dysfunction are atherosclerosis' characteristics. It is believed that the occurrence and development of atherosclerosis mainly include endothelial cell damage, lipoprotein deposition, inflammation and fibrous cap formation, but its molecular mechanism has not been elucidated. Therefore, protecting the vascular endothelium from damage is one of the key factors against atherosclerosis. The factors and processes involved in vascular endothelial injury are complex. Finding out the key factors and mechanisms of atherosclerosis caused by vascular endothelial injury is an important target for reversing and preventing atherosclerosis. Changes in cell adhesion are the early characteristics of EndMT, and cell adhesion is related to vascular endothelial injury and atherosclerosis. Recent researches have exhibited that endothelial-mesenchymal transition (EndMT) can urge atherosclerosis' progress, and it is expected that inhibition of EndMT will be an object for anti-atherosclerosis. We speculate whether inhibition of EndMT can become an effective target for reversing atherosclerosis by improving cell adhesion changes and vascular endothelial injury. Studies have shown that H₂S has a strong cardiovascular protective effect. As H₂S has anti- inflammatory, anti-oxidant, inhibiting foam cell formation, regulating ion channels and enhancing cell adhesion and endothelial functions, the current research on H₂S in cardiovascular aspects is increasing, but anti-atherosclerosis's molecular mechanism and the function of H2S in EndMT have not been explicit. In order to explore the mechanism of H₂S against atherosclerosis, to find an effective target to reverse atherosclerosis, we sum up the progress of EndMT promoting atherosclerosis, and Hydrogen sulfide's potential anti- EndMT effect is discussed in this review.

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

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

PI3K/AKT pathway mediates the antidepressant- and anxiolytic-like roles of hydrogen sulfide in streptozotocin-induced diabetic rats via promoting hippocampal neurogenesis

We have previously demonstrated that hydrogen sulfide (H₂S), the third endogenous gasotransmitter, ameliorates the depression- and anxiety-like behaviors in diabetic rats, but the underlying mechanism remains unclear. The present was aimed to investigate whether the hippocampal phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway mediates H₂S-ameliorated depression- and anxiety-like behaviors in diabetic rats by improving the hippocampal neurogenesis. The depression-like behaviors were examined by Tail suspension test (TST), the anxiety-like behaviors were examined by Elevated plus maze test (EPM), and the locomotor activity was detected by Open Field Test (OFT). The expressions of doublecortin (DCX), neuron-specific nuclear protein (NeuN), glial fibrillary acidic protein (GFAP), p-AKT, and AKT in the hippocampus were determined by Western blot analysis. Results showed that NaHS, a donor of exogenous H₂S, not only activated the hippocampal PI3K/AKT pathway, as evidenced by the increase of phosphorylated AKT, but also favorably reversed streptozotocin (STZ)-disturbed hippocampal neurogenesis, as evidenced by the increases in the expressions of DCX and NeuN as well as the decrease in the expression of GFAP in the hippocampus of STZ-induced diabetic rats. Furthermore, inhibited PI3K/AKT pathway by LY294002 significantly abolished H₂S-exerted the improvement of hippocampal neurogenesis and the antidepressant- and anxiolytic-like effects in the STZ-induced diabetic rats. Taken together, these results uncover that the activation of hippocampal PI3K/AKT pathway plays an important role to restore hippocampal neurogenesis and subsequently to mediate the antidepressant- and anxiolytic-like roles of H₂S in STZ-induced diabetic rats and enhance our understanding of the robustness of H₂S as a therapeutic strategy for treatment of depression in diabetes mellitus.

Exogenous hydrogen sulfide and miR-21 antagonism attenuates macrophage-mediated inflammation in ischemia reperfusion injury of the aged kidney

Ischemia reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in the aging population. A reduction of hydrogen sulfide (H2S) production in the old kidney and renal IRI contribute to renal pathology and injury. Recent studies suggest that microRNAs (miRs) play an important role in the pathophysiology of AKI and a significant crosstalk exists between H2S and miRs. Among the miRs, miR-21 is highly expressed in AKI and is reported to have both pathological and protective role. In the present study, we sought to determine the effects of age-induced reduction in H2S and mir-21 antagonism in AKI. Wild type (WT, C57BL/6J) mice aged 12-14 weeks and 75-78 weeks underwent bilateral renal ischemia (27 min) and reperfusion for 7 days and were treated with H2S donor, GYY4137 (GYY, 0.25 mg/kg/day, ip) or locked nucleic acid anti-miR-21 (20 mg/kg b.w., ip) for 7 days. Following IRI, old kidney showed increased macrophage polarization toward M1 inflammatory phenotype, cytokine upregulation, endothelial-mesenchymal transition, and fibrosis compared to young kidney. Treatment with GYY or anti-miR-21 reversed the changes and improved renal vascular density, blood flow, and renal function in the old kidney. Anti-miR-21 treatment in mouse glomerular endothelial cells showed upregulation of H2S-producing enzymes, cystathionine β-synthase (CBS), and cystathionineγ-lyase (CSE), and reduction of matrix metalloproteinase-9 and collagen IV expression. In conclusion, exogenous H2S and inhibition of miR-21 rescued the old kidney dysfunction due to IRI by increasing H2S levels, reduction of macrophage-mediated injury, and promoting reparative process suggesting a viable approach for aged patients sustaining AKI.

Hydrogen sulfide ameliorates doxorubicin‑induced myocardial fibrosis in rats via the PI3K/AKT/mTOR pathway

The present study aimed to determine the role and regulatory mechanism of hydrogen sulfide (H2S) in the amelioration of doxorubicin‑induced myocardial fibrosis in rats. It is hypothesized that the PI3K/AKT/mTOR signaling pathway is regulated to inhibit endoplasmic reticulum stress (ERS) and autophagy to reduce myocardial fibrosis. A total of 40 adult male Sprague Dawley rats were randomly divided into 4 groups (n=10/group). The 4 groups included the normal control group (control group), model group [doxorubicin (Dox) group], H2S intervention model group (H2S+Dox group) and H2S control group (H2S group). The model used in the present study was constructed by administering intraperitoneal injections of doxorubicin (3.0 mg/kg every other day; total of 6 injections). In addition, the intervention factor, NaHS and the donor of H2S, was also administered by intraperitoneal injection (56 µmol/kg/day), which lasted a month. Pathological changes in the rats were observed using Masson staining and transmission electron microscopy, while the protein expression levels of MMPs/TIMPs, transforming growth factor‑β1, cystathionine lyase and PI3K/AKT/mTOR, which are autophagy‑related and ERS‑related proteins were detected in myocardial tissues using western blot analysis. The gene expression levels of collagen type I α‑2 chain and collagen type III α‑1 chain were detected using reverse transcription‑quantitative PCR and the quantification of myocardial H2S content was performed using ELISA. In the Dox group compared with that in the control group, myocardial fibers were significantly disordered, while the protein expression levels of ERS‑related and autophagy‑related proteins were increased markedly, and the expression levels of PI3K/AKT/mTOR proteins were reduced markedly. The aforementioned changes were markedly reversed following H2S intervention, which indicated that H2S exerts a positive protective effect on doxorubicin‑induced myocardial fibrosis. The protective mechanism of H2S intervention in myocardial fibrosis is hypothesized to be associated with the inhibition of overactivation of the ER and that of autophagy via upregulation of the PI3K/AKT/mTOR pathway.

The Potential of Hydrogen Sulfide Donors in Treating Cardiovascular Diseases

Hydrogen sulfide (H2S) has long been considered as a toxic gas, but as research progressed, the idea has been updated and it has now been shown to have potent protective effects at reasonable concentrations. H2S is an endogenous gas signaling molecule in mammals and is produced by specific enzymes in different cell types. An increasing number of studies indicate that H2S plays an important role in cardiovascular homeostasis, and in most cases, H2S has been reported to be downregulated in cardiovascular diseases (CVDs). Similarly, in preclinical studies, H2S has been shown to prevent CVDs and improve heart function after heart failure. Recently, many H2S donors have been synthesized and tested in cellular and animal models. Moreover, numerous molecular mechanisms have been proposed to demonstrate the effects of these donors. In this review, we will provide an update on the role of H2S in cardiovascular activities and its involvement in pathological states, with a special focus on the roles of exogenous H2S in cardiac protection.

Effects of D-pinitol on myocardial apoptosis and fibrosis in streptozocin-induced aging-accelerated mice

Diabetic cardiomyopathy (DCM) causes heart failure and increases the mortality in diabetic patients. Myocardial apoptosis and fibrosis are the main features of DCM and aging. The aim is to study the underlying mechanism of D-pinitol (DP) on myocardial apoptosis and fibrosis in an elderly diabetic mouse model. The diabetic model was established by SAMP-8 mice that were injected with streptozotocin daily for five consecutive days. The mice were administrated of DP (150 mg kg^-1  day^-1 ) by gavage for 10 weeks. The common metabolic disorder indices, cardiac dysfunction, oxidative stress, myocardial apoptosis and fibrosis, and PI3K/Akt/mTOR pathway were investigated. Our findings suggested that DP has a protective effect on DCM, which may be related to regulating oxidative stress, and PI3K/Akt/mTOR pathway involving cardiac fibrosis and apoptosis. DP may be a novel clinical application in fighting against DCM. PRACTICAL APPLICATIONS: D-pinitol (DP) was found in large quantities in soybean and legume foods. DP has a variety of functions, including hypoglycemic, anti-oxidation, anti-inflammatory, cardioprotective, and anti-tumor activity. We used the streptozotocin-induced SAMP8 mice as the diabetic model and treated with DP. We found that DP can improve cardiac dysfunction and inhibits the oxidative stress, myocardial apoptosis and fibrosis. DP has a significant effect on diabetic cardiomyopathy (DCM). The molecular mechanisms are related to regulating oxidative stress, and PI3K/Akt/mTOR pathway involving cardiac fibrosis and apoptosis. DP can prevent and/or delay the onset of DCM.

Exogenous hydrogen sulfide inhibits apoptosis by regulating endoplasmic reticulum stress-autophagy axis and improves myocardial reconstruction after acute myocardial infarction

During acute myocardial infarction, endoplasmic reticulum (ER) stress-induced autophagy and apoptosis have been shown as important pathogeneses of myocardial reconstruction. Importantly, hydrogen sulfide (H2S), as a third endogenous gas signaling molecule, exerts strong cytoprotective effect on anti-ER stress, autophagy regulation and antiapoptosis. Here, we showed that H2S treatment inhibits apoptosis by regulating ER stress-autophagy axis and improves myocardial reconstruction after acute myocardial infarction. We found that H2S intervention improved left ventricle function, reduced glycogen deposition in myocardial tissue mesenchyme, and inhibited apoptosis. Moreover, the expressions of fibrosis indicators (Col3a1 and Col1a2), ER stress-related proteins (CHOP and BIP/ERP78), autophagy-related proteins (Beclin and ATG5), apoptosis protein (Bax), as well as fibrosis protein Col4a3bp were all decreased after treatment with H2S. H2S administration also maintained MMP/TIMP balance. Mechanistically, H2S activated the PI3K/AKT signaling pathway. In addition, H2S treatment also reduced the expressions of ER stress-related proteins, autophagy-related proteins, and apoptins in in vitro experiments. Interestingly, activation of ER stress-autophagy axis could reverse the inhibitory effect of H2S on myocardial apoptosis. Altogether, these results suggested that exogenous H2S suppresses myocardial apoptosis by blocking ER stress-autophagy axis, which in turn reverses cardiac remodeling after myocardial infarction.

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

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

Hydrogen Sulfide Switch Phenomenon Regulating Autophagy in Cardiovascular Diseases

Hydrogen sulfide (H₂S), a novel gaseous signaling molecule, is a vital physiological signal in mammals. H₂S protects the cardiovascular system via modulation of vasodilation, vascular remodeling, and inhibition of vascular calcification, and also has anti-atherosclerosis properties. Autophagy is a lysosomal-mediated intracellular degradation mechanism for excessive or abnormal proteins and lipids. The contribution of autophagy to normal and disease-state cell physiology is extremely complicated. Autophagy acts as a double-edged sword in the cardiovascular system. It can defend against damage to cells caused by environmental changes and it can also induce active cell death under certain conditions. In recent years, accumulating evidence indicates that H₂S can up- or downregulate autophagy in many pathological processes, thereby switching from a harmful to a beneficial role. In this review, we summarize progress on understanding the mechanism by which H₂S regulates autophagy in cardiovascular disease. We also discuss a H₂S switch phenomenon that regulates autophagy and provides protection in cardiovascular diseases.

Hydrogen sulfide is a regulator of mammary gland development in prepubescent female mice

The present study aimed to investigate the effects of exogenous H2S on mammary gland development in pubescent mice and to explore the underlying mechanism. The mouse mammary epithelial cell line HC11, along with C57BL/6J mice, were treated with different concentrations of sodium hydrosulfide (NaHS), which is a donor of H2S. The HC11 cell viability, pubescent mammary gland development, and the involvement of proliferative proteins and pathways were assessed by CCK‑8 assay, EdU assay, whole mount staining, H&E staining, western blotting and reverse transcription‑quantitative PCR. Both in vitro and in vivo, a low concentration of NaHS (100 µM in vitro; 9 mg/kg in vivo) significantly promoted the viability of HC11 cells and the development of mammary glands by increasing the expression of the proliferative markers cyclin D1/3 and proliferating cell nuclear antigen. However, a high concentration of NaHS (1,000 µM in vitro; 18 mg/kg in vivo) inhibited HC11 cell viability, mammary gland development and the expression levels of proteins involved in proliferation. Subsequent experiments revealed that NaHS regulated the phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (Akt)‑mammalian target of rapamycin (mTOR) signaling pathway during this process. In vivo, intraperitoneal injection of low concentration NaHS (9 mg/kg) activated the PI3K/Akt‑mTOR pathway in mammary glands of pubescent mice, increased the secretion of insulin‑like growth factor 1 (IGF‑1) and estradiol (E2), and then stimulated mammary gland ductal development. Whereas a high concentration of NaHS (18 mg/kg) elicited the opposite effects to those of low‑dose NaHS. In conclusion, the present study demonstrated that exogenous H2S supplied by NaHS may exert bidirectional effects on mammary gland ductal development; promoting ductal development at a low concentration and inhibiting it at a high concentration. The effects of H2S may occur via the intracellular PI3K/Akt‑mTOR signaling pathway, or by regulation of the secretion of IGF‑1 and E2.

Exogenous Hydrogen Sulfide Ameliorates Diabetic Myocardial Fibrosis by Inhibiting Cell Aging Through SIRT6/AMPK Autophagy

Stress aging of myocardial cells participates in the mechanism of myocardial fibrosis (MF). Previous studies have shown that hydrogen sulfide (H₂S) can improve MF, however the specific internal mechanism remains still unclear. Therefore, this study aims to explore whether H₂S can improve myocardial cell aging induced by high glucose and myocardial fibrosis in diabetic rats by activating autophagy through SIRT6/AMPK. We observed that HG (high glucose, 33 mM) induced down-regulation of endogenous H₂S-producing enzyme CSE protein expression, increased cell senescence, down-regulation of autophagy-related proteins Beclin1, Atg5, Atg12, Atg16L1, and inhibition of SIRT6/AMPK signaling pathway in H9c2 cardiomyocytes. H₂S (NaHS: 400 μM) could up-regulate CSE protein expression, inhibit cell senescence, activate autophagy and SIRT6/AMPK signaling pathway. On the contrary, no above phenomena was achieved upon addition of CSE inhibitor PAG (dl-propargylglycine: mmol/L). In order to further elucidate the relationship between H₂S and SIRT6/AMPK signaling pathway, dorsomorphin dihydrochloride (Dor), an inhibitor of AMPK signaling pathway, was added to observe the reversal of H₂S’s inhibitory effect on myocardial cell aging. At the same, streptozotocin (STZ; 40 mg/kg) was injected intraperitoneally to build an animal model of diabetic SD rats. The results showed that myocardial collagen fibers were significantly deposited, myocardial tissue senescent cells were significantly increased and the expression of CSE protein was down-regulated, while SIRT6/AMPK signaling pathway and cell autophagy were significantly inhibited. H₂S-treated (NaHS; 56 μmol/kg) could significantly reverse the above phenomenon. In conclusion, these findings suggest that exogenous H₂S can inhibit myocardial cell senescence and improve diabetic myocardial fibrosis by activating CSE and autophagy through SIRT6/AMPK signaling pathway.

miR-214-3p Attenuates Sepsis-Induced Myocardial Dysfunction in Mice by Inhibiting Autophagy through PTEN/AKT/mTOR Pathway

Aims. More than half of the patients with sepsis would develop cardiac dysfunction, which is termed as sepsis-induced myocardial dysfunction (SIMD). Previous studies suggest that autophagy may play an important role in SIMD. The present study investigated whether miR-214-3p could attenuate SIMD by inhibiting autophagy. Main Methods. In this article, we investigated the role of autophagy in a mouse model of cecal ligation and puncture (CLP). The structure and function of hearts harvested from the mice were evaluated. Myocardial autophagy levels were detected with immunohistochemical, immunofluorescent, and Western blot. Key Findings. miR-214-3p can alleviate SIMD in septic mice by inhibiting the level of cardiac autophagy to attenuate myocardial dysfunction. Moreover, this study showed that miR-214-3p inhibited autophagy by silencing PTEN expression in the myocardial tissues of septic mice. Significance. This study showed that miR-214-3p attenuated SIMD through myocardial autophagy inhibition by silencing PTEN expression and activating the AKT/mTOR pathway. The present findings supported that miR-214-3p may be a potential therapeutic target for SIMD.

Exogenous hydrogen sulfide reduces atrial remodeling and atrial fibrillation induced by diabetes mellitus via activation of the PI3K/Akt/eNOS pathway

Diabetes mellitus (DM) facilitates atrial fibrosis and increases the risk of atrial fibrillation (AF). The underlying mechanism of DM in causing AF remains mostly unknown and potential therapeutic targets for DM‑induced AF are rarely reported. Hydrogen sulfide (H2S) has drawn considerable attention in recent years for its potential as a cardiovascular protector. Thus, the aim of the present study was to investigate the effect of H2S on DM‑induced AF and the mechanism of action. Sprague‑Dawley rats were divided into four groups, including the control group, the DM group, the H2S group and the DM+H2S group. The DM group and the DM+H2S group were administered streptozotocin to induce DM, whereas the other two groups were given citrate buffer as a control. The H2S group and the DM+H2S group were administered with an intraperitoneal injection of sodium hydrosulfide (precursor of H2S). AF inducibility, AF duration, atrial fibrosis and vital protein expression of oxidative stress were compared among the four groups. The DM group showed significantly higher AF incidence rates and duration (P<0.05). Histology results demonstrated severe atrial fibrosis in the DM group, and the PI3K/Akt/endothelial nitric oxide synthase (eNOS) pathway was significantly downregulated (P<0.05). However, when H2S was administered, the rats showed lower AF incidence and duration compared with the DM group. Additionally, H2S was able to mitigate the atrial fibrosis induced by DM, as well as the proliferation and migration of cardiac fibroblasts, as demonstrated by an MTT assay and real‑time cell analyzer migration experiment. Western blotting showed that the expression levels of the PI3K/Akt/eNOS pathway in the DM+H2S group were significantly upregulated compared with those of the DM group (P<0.05). In summary, DM status can lead to the structural remodeling of atrial fibrosis, facilitating AF incidence and persistence. Administration of H2S does not affect the glucose level, but can significantly mitigate atrial fibrosis and reduce the incidence of AF induced by DM, probably via activation of the PI3K/Akt/eNOS pathway.

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

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

Hydrogen sulfide plays an important protective role by influencing autophagy in diseases

Autophagy can regulate cell growth, proliferation, and stability of cell environment. Its dysfunction can be involved in a variety of diseases. Hydrogen sulfide (H(2)S) is an important signaling molecule that regulates many physiological and pathological processes. Recent studies indicate that H(2)S plays an important protective role in many diseases through influencing autophagy, but its mechanism is not fully understood. This article reviewed the progress about the effect of H(2)S on autophagy in diseases in recent years in order to provide theoretical basis for the further research on the interaction of H(2)S and autophagy and the mechanisms involved.

STAT1-avtiviated LINC00961 regulates myocardial infarction by the PI3K/AKT/GSK3β signaling pathway

Myocardial infarction (MI) remains a severe cardiac disease because of its high incidence and mortality worldwide. A growing body of recent investigations have confirmed that LINC00961 acts as a tumor suppressor in diverse malignancies. However, the biological significance of LINC00961 and its molecular mechanism in MI are still elusive. Hypoxia is the leading cause of MI and induces myocardial injury. In this study, we found the upregulated expression of LINC00961 in cardiomyocytes H9c2 after hypoxia treatment. Knockdown of LINC00961 ameliorated hypoxia-induced cell injury by facilitating cell viability while repressing cell apoptosis. The significant increase of signal transducer and activator of transcription 1 (STAT1) expression and phosphorylation levels was observed in hypoxia-induced cells and proved to exacerbate hypoxia injury. In addition, STAT1 transcriptionally activated LINC00961 by binding to LINC00961 promoter. Furthermore, our results validated that suppressing LINC00961 contributed to the remarkable diminution in the phosphorylation levels of phosphoinositide 3-kinases (PI3K), AKT, and glycogen synthase kinase-3β (GSK3β). Inhibition of PI3K/AKT signaling or GSK3β pathway rescued the effects of LINC00961 knockdown on the hypoxia-induced injury of cardiomyocytes. Namely, we concluded that STAT1-avtiviated LINC00961 accelerated MI via the PI3K/AKT/GSK3β pathway, which may provide clues for the treatment of patients with MI.

Altered gene expression of hydrogen sulfide-producing enzymes in the liver and muscles tissues of hyperthyroid rats

Thyroid hormones have a role in the regulation of hydrogen sulfide (H₂ S) biosynthesis. In this study, we determined the effects of hyperthyroidism on H₂ S levels in various tissues and messenger RNA (mRNA) expression of cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST) in the liver and muscles of the rat. Sixteen male Wistar rats were divided into the hyperthyroid and the control groups. Hyperthyroidism was induced by adding l-thyroxine (12 mg/L) to drinking water for a period of 21 days. H₂ S concentrations in serum, liver, aorta, heart, and soleus muscles, as well as mRNA expressions of CBS, CSE, and 3-MST in these tissues were measured at Day 21. Hyperthyroid rats had lower H₂ S levels in the serum compared with controls (14.7 ± 1.4 vs. 25.7 ± 1.6 µmol/L, p < 0.001). Compared with controls, hyperthyroid rats had lower levels of H₂ S in the aorta (89%), heart (80%), and soleus (103%) muscles, but higher levels in the liver (35%). Hyperthyroidism decreased the ratio of CBS/CSE mRNA expression in the liver and the CSE/CBS mRNA expression in the muscles by decreasing CBS levels in liver (34% cf. controls) and CSE levels in the aorta, heart, and soleus muscles (respectively, 51%, 7%, and 52% cf.). In addition, hyperthyroidism decreased the mRNA expression of 3-MST in the liver (51%) and aorta (33%), and increased it in the heart (300%) and soleus muscle (182%). In conclusion, hyperthyroidism increased H₂ S levels in the liver and decreased it in muscles; these effects are at least in part due to increases and decreases in expression of CSE in the liver and muscles, respectively. These data indicate an association between thyroid hormone status and gene expression of the H₂ S-producing enzymes in the rat.

MicroRNAs as Potential Pharmaco-targets in Ischemia-Reperfusion Injury Compounded by Diabetes

BACKGROUND

Ischemia-Reperfusion (I/R) injury is the tissue damage that results from re-oxygenation of ischemic tissues. There are many players that contribute to I/R injury. One of these factors is the family of microRNAs (miRNAs), which are currently being heavily studied. This review aims to critically summarize the latest papers that attributed roles of certain miRNAs in I/R injury, particularly in diabetic conditions and dissect their potential as novel pharmacologic targets in the treatment and management of diabetes.

METHODS

PubMed was searched for publications containing microRNA and I/R, in the absence or presence of diabetes. All papers that provided sufficient evidence linking miRNA with I/R, especially in the context of diabetes, were selected. Several miRNAs are found to be either pro-apoptotic, as in the case of miR-34a, miR-144, miR-155, and miR-200, or anti-apoptotic, as in the case of miR-210, miR-21, and miR-146a. Here, we further dissect the evidence that shows diverse cell-context dependent effects of these miRNAs, particularly in cardiomyocytes, endothelial, or leukocytes. We also provide insight into cases where the possibility of having two miRNAs working together to intensify a given response is noted.

CONCLUSIONS

This review arrives at the conclusion that the utilization of miRNAs as translational agents or pharmaco-targets in treating I/R injury in diabetic patients is promising and becoming increasingly clearer.