Hydrogen Sulfide Protects Human Cardiac Fibroblasts Against H2O2-induced Injury Through Regulating Autophagy-Related Proteins

Novel ray of hope for diabetic wound healing: Hydrogen sulfide and its releasing agents

BACKGROUND

Diabetes mellitus (DM) is a long-term metabolic disease accompanied by difficulties in wound healing placing a severe financial and physical burden on patients. As one of the important signal transduction molecules, both endogenous and exogenous hydrogen sulfide (H2S) was found to promote diabetic wound healing in recent studies. H2S at physiological concentrations can not only promote cell migration and adhesion functions, but also resist inflammation, oxidative stress and inappropriate remodeling of the extracellular matrix.

AIM OF REVIEW

The purpose of this review is to summarize current research on the function of H2S in diabetic wound healing at all stages, and propose future directions.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, first, the various factors affecting wound healing under diabetic pathological conditions and the in vivo H2S generation pathway are briefly introduced. Second, how H2S may improve diabetic wound healing is categorized and described. Finally, we discuss the relevant H2S donors and new dosage forms, analyze and reveal the characteristics of many typical H2S donors, which may provide new ideas for the development of H2S-released agents to improve diabetic wound healing.

Recent advances in the mechanism of hydrogen sulfide in wound healing in diabetes

Wound healing difficulties in diabetes continue to be a clinical challenge, posing a considerable burden to patients and society. Recently, exploration of the mechanism of wound healing and associated treatment options in diabetes has become topical. Of note, the positive role of hydrogen sulfide in promoting wound healing has been demonstrated in recent studies. Hydrogen sulfide is a confirmed gas transmitter in mammals, playing an essential role in pathology and physiology. This review describes the mechanism underlying the role of hydrogen sulfide in the promotion of diabetic wound healing and the potential for hydrogen sulfide supplementation as a therapeutic application.

Regulation of cardiac fibroblast cell death by unfolded protein response signaling

The endoplasmic reticulum (ER) is a tightly regulated organelle that requires specific environmental properties to efficiently carry out its function as a major site of protein synthesis and folding. Embedded in the ER membrane, ER stress sensors inositol-requiring enzyme 1 (IRE1), protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), and activating transcription factor 6 (ATF6) serve as a sensitive quality control system collectively known as the unfolded protein response (UPR). In response to an accumulation of misfolded proteins, the UPR signals for protective mechanisms to cope with the cellular stress. Under prolonged unstable conditions and an inability to regain homeostasis, the UPR can shift from its original adaptive response to mechanisms leading to UPR-induced apoptosis. These UPR signaling pathways have been implicated as an important feature in the development of cardiac fibrosis, but identifying effective treatments has been difficult. Therefore, the apoptotic mechanisms of UPR signaling in cardiac fibroblasts (CFs) are important to our understanding of chronic fibrosis in the heart. Here, we summarize the maladaptive side of the UPR, activated downstream pathways associated with cell death, and agents that have been used to modify UPR-induced apoptosis in CFs.

Evaluating the Effect of Hydrogen Sulfide in the Idiopathic Pulmonary Fibrosis Model with a Fluorescent Probe

Hydrogen sulfide (H₂S), a gaseous signaling molecule, is involved in a wide range of physiological and pathological processes. H₂S has been proven to play a beneficial role in lung diseases, and the relationship between perturbations in endogenous H₂S synthesis and degree with idiopathic pulmonary fibrosis (IPF) has attacted increasing attention. However, the changes in endogenous lung H₂S levels in the pathological progression of chronic pulmonary diseases remain unclear. To this end, we synthesized a fluorescent probe (Bcy-HS) for the selective imaging of H₂S in living cells and mice. This probe was mainly used for in situ in vivo and cellular imaging as well as a systematic assessment of intrapulmonary H₂S levels at different stages of IPF. In addition, we also discussed the potential of H₂S supplementation in the treatment of pulmonary fibrotic diseases. Our results confirmed the key role of H₂S in pulmonary fibrosis. In cellular and mice models of pulmonary fibrosis, intracellular H₂S levels are reduced. However, the severity of oxidative damage and pulmonary fibrosis decreased after NaSH (H₂S donor). Therefore, we concluded that increasing the H₂S content in vivo may be a novel strategy for IPF treatment.

Cardioprotective effects of hydrogen sulfide in attenuating myocardial ischemia‑reperfusion injury (Review)

Ischemic heart disease is one of the major causes of cardiovascular‑related mortality worldwide. Myocardial ischemia can be attenuated by reperfusion that restores the blood supply. However, injuries occur during blood flow restoration that induce cardiac dysfunction, which is known as myocardial ischemia‑reperfusion injury (MIRI). Hydrogen sulfide (H₂S), the third discovered endogenous gasotransmitter in mammals (after NO and CO), participates in various pathophysiological processes. Previous in vitro and in vivo research have revealed the protective role of H₂S in the cardiovascular system that render it useful in the protection of the myocardium against MIRI. The cardioprotective effects of H₂S in attenuating MIRI are summarized in the present review.

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.

Protocatechualdehyde protects oxygen-glucose deprivation/reoxygenation-induced myocardial injury via inhibiting PERK/ATF6α/IRE1α pathway

Endoplasmic reticulum (ER) stress has been considered as a promising strategy in developing novel therapeutic agents for cardiovascular diseases through inhibiting cardiomyocyte apoptosis. Protocatechualdehyde (PCA) is a natural phenolic compound from medicinal plant Salvia miltiorrhiza with cardiomyocyte protection. However, the potential mechanism of PCA on cardiovascular ischemic injury is largely unexplored. Here, we found that PCA exerted markedly anti-apoptotic effect in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced H9c2 cells (Rat embryonic ventricular H9c2 cardiomyocytes), which was detected by 3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT), lactate dehydrogenase (LDH), Hoechst 33258 and acridine orange/ethidium bromide (AO/EB) assays. PCA also obviously protected cardiomyocytes in myocardial fibrosis model of mice, which was determined by hematoxylin-eosin (HE) staining and TdT-mediated dUTP Nick-End Labeling (TUNEL) staining. Transcriptomics coupled with bioinformatics analysis revealed a complex pharmacological signaling network especially for PCA-mediated ER stress on cardiomyocytes. Further mechanism study suggested that PCA suppressed ER stress via inhibiting protein kinase R-like ER kinase (PERK), inositol-requiring enzyme1α (IRE1α), and transcription factor 6α (ATF6α) signaling pathway through Western blot, DIOC6 and ER-Tracker Red staining, leading to a protective effect against ER stress-mediated cardiomyocyte apoptosis. Taken together, our observations suggest that PCA is a major component from Salvia miltiorrhiza against cardiovascular ischemic injury by suppressing ER stress-associated PERK, IRE1α and ATF6α signaling pathways.

Hydrogen Sulfide: From a Toxic Molecule to a Key Molecule of Cell Life

Hydrogen sulfide (H2S) has always been considered toxic, but a huge number of articles published more recently showed the beneficial biochemical properties of its endogenous production throughout all regna. In this review, the participation of H2S in many physiological and pathological processes in animals is described, and its importance as a signaling molecule in plant systems is underlined from an evolutionary point of view. H2S quantification methods are summarized and persulfidation is described as the underlying mechanism of action in plants, animals and bacteria. This review aims to highlight the importance of its crosstalk with other signaling molecules and its fine regulation for the proper function of the cell and its survival.

Hydrogen Sulfide Attenuates β2-Microglobulin-Induced Cognitive Dysfunction: Involving Recovery of Hippocampal Autophagic Flux

BACKGROUND AND AIM

Accumulation of β2-microglobulin (B2M), a systemic pro-aging factor, regulates negatively cognitive function. Hydrogen sulfide (H2S), a novel gas signaling molecule, exerts protection against cognitive dysfunction. Therefore, the present work was designed to explore whether H2S attenuates cognitive dysfunction induced by B2M and the underlying mechanism.

MATERIALS AND METHODS

The cognitive function of rats was assessed by Y-maze, Novel object recognition (NOR), and Morris water maze (MWM) tests. The levels of autophagosome and autolysosome in hippocampus were observed by transmission electron microscopy. The expression of p62 protein in hippocampus was detected by western blot analysis.

RESULTS

NaHS (a donor of H2S) significantly alleviated cognitive impairments in the B2M-exposed rats tested by Y-maze test, NOR test and MWM test. Furthermore, NaHS recovered autophagic flux in the hippocampus of B2M-exposed rats, as evidenced by decreases in the ratio of autophagosome to autolysosome and the expression of p62 protein in the hippocampus.

CONCLUSION

In summary, these data indicated that H2S attenuates B2M-induced cognitive dysfunction, involving in recovery of the blocked autophagic flux in the hippocampus, and suggested that H2S may be a novel approach to prevent B2M-induced cognitive dysfunction.

Sodium hydrosulphide restores tumour necrosis factor-α-induced mitochondrial dysfunction and metabolic dysregulation in HL-1 cells

Tumour necrosis factor (TNF)‐α induces cardiac metabolic disorder and mitochondrial dysfunction. Hydrogen sulphide (H₂S) contains anti‐inflammatory and biological effects in cardiomyocytes. This study investigated whether H₂S modulates TNF‐α‐dysregulated mitochondrial function and metabolism in cardiomyocytes. HL‐1 cells were incubated with TNF‐α (25 ng/mL) with or without sodium hydrosulphide (NaHS, 0.1 mmol/L) for 24 hours. Cardiac peroxisome proliferator‐activated receptor (PPAR) isoforms, pro‐inflammatory cytokines, receptor for advanced glycation end products (RAGE) and fatty acid metabolism were evaluated through Western blotting. The mitochondrial oxygen consumption rate and adenosine triphosphate (ATP) production were investigated using Seahorse XF24 extracellular flux analyzer and bioluminescence assay. Fluorescence intensity using 2′, 7′‐dichlorodihydrofluorescein diacetate was used to evaluate mitochondrial oxidative stress. NaHS attenuated the impaired basal and maximal respiration, ATP production and ATP synthesis and enhanced mitochondrial oxidative stress in TNF‐α‐treated HL‐1 cells. TNF‐α‐treated HL‐1 cells exhibited lower expression of PPAR‐α, PPAR‐δ, phosphorylated 5′ adenosine monophosphate‐activated protein kinase‐α2, phosphorylated acetyl CoA carboxylase, carnitine palmitoyltransferase‐1, PPAR‐γ coactivator 1‐α and diacylglycerol acyltransferase 1 protein, but higher expression of PPAR‐γ, interleukin‐6 and RAGE protein than control or combined NaHS and TNF‐α‐treated HL‐1 cells. NaHS modulates the effects of TNF‐α on mitochondria and the cardiometabolic system, suggesting its therapeutic potential for inflammation‐induced cardiac dysfunction.

Hydrogen Sulfide Attenuates Hydrogen Peroxide-Induced Injury in Human Lung Epithelial A549 Cells

Lung tissues are frequently exposed to a hyperoxia environment, which leads to oxidative stress injuries. Hydrogen sulfide (H₂S) is widely implicated in physiological and pathological processes and its antioxidant effect has attracted much attention. Therefore, in this study, we used hydrogen peroxide (H₂O₂) as an oxidative damage model to investigate the protective mechanism of H₂S in lung injury. Cell death induced by H₂O₂ treatment could be significantly attenuated by the pre-treatment of H₂S, resulting in a decrease in the Bax/Bcl-2 ratio and the inhibition of caspase-3 activity in human lung epithelial cell line A549 cells. Additionally, the results showed that H₂S decreased reactive oxygen species (ROS), as well as neutralized the damaging effects of H₂O₂ in mitochondria energy-producing and cell metabolism. Pre-treatment of H₂S also decreased H₂O₂-induced suppression of endogenous H₂S production enzymes, cystathionine-beta-synthase (CBS), cystathionine-gamma-lyase (CSE), and 3-mercapto-pyruvate sulfurtransferase (MPST). Furthermore, the administration of H₂S attenuated [Ca²⁺] overload and endoplasmic reticulum (ER) stress through the mitogen-activated protein kinase (MAPK) signaling pathway. Therefore, H₂S might be a potential therapeutic agent for reducing ROS and ER stress-associated apoptosis against H₂O₂-induced lung injury.

Hydrogen sulfide protects H9c2 cardiomyoblasts against H2O2-induced apoptosis

Reactive oxygen species (ROS) are highly reactive chemical species that may cause irreversible tissue damage, and play a critical role in cardiovascular diseases. Hydrogen sulfide (H2S) is a gasotransmitter that acts as a ROS scavenger with cardio-protective effects. In this study, we investigated the cytoprotective effect of H2S against H2O2-induced apoptosis in cardiomyocytes. H9c2 rat cardiomyoblasts were treated with H2S (100 μM) 24 h before challenging with H2O2 (100 μM). Apoptosis was then assessed by annexin V and PI, and mitochondrial membrane potential was measured using a fluorescent probe, JC-1. Our results revealed that H2S improved cell viability, reduced the apoptotic rate, and preserved mitochondrial membrane potential. An increased Bcl-2 to Bax ratio was also seen in myocytes treated with H2S after H2O2-induced stress. Our findings indicated a therapeutic potential for H2S in preventing myocyte death following ischemia/reperfusion.

Effect of H2S on gastric ischemia-reperfusion injury in rats

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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