Hydrogen sulfide signaling in mitochondria and disease

Near-infrared Rhodols-based fluorescent probe with large Stokes shift for tracking of H2S in food spoilage and living cells

Hydrogen sulfide (H2S), as a biomarker signaling gas, is not only susceptible to food spoilage, but also plays a key function in many biological processes. In this work, an activated near infrared (NIR) H2S fluorescent probe was designed and synthesized with quinoline-conjugated Rhodols dye as fluorophore skeleton and a dinitrophenyl group as the responsive moiety. Due to the quenching effect of dinitrophenyl group and the closed-loop structure of Rhodols fluorophore, probe itself has a very weak absorption and fluorescence background signal. After the H2S-induced thiolysis reaction, the probe exhibits a remarkable colormetric change and NIR fluorescent enhancement response at 716 nm with large Stokes shift (116 nm), and possesses high sensing selectivity and sensitivity with a low detection limits of 330 nM. The response mechanism is systematically characterized by 1H NMR, MS and DFT calculations. The colorimetric change allows the probe to be used as a test strips to detect H2S in food spoilage, while NIR fluorescent response helps the probe monitor intracellular H2S.

Exploring the impact of hydrogen sulfide on hematologic malignancies: A review

Hydrogen sulfide (H2S) is one of the three most crucial gaseous messengers in the body. The discovery of H2S donors, coupled with its endogenous synthesis capability, has sparked hope for the treatment of hematologic malignancies. In the last decade, the investigation into the impact of H2S has expanded, particularly within the fields of cardiovascular function, inflammation, infection, and neuromodulation. Hematologic malignancies refer to a diverse group of cancers originating from abnormal proliferation and differentiation of blood-forming cells, including leukemia, lymphoma, and myeloma. In this review, we delve deeply into the complex interrelation between H2S and hematologic malignancies. In addition, we comprehensively elucidate the intricate molecular mechanisms by which both H2S and its donors intricately modulate the progression of tumor growth. Furthermore, we systematically examine their impact on pivotal aspects, encompassing the proliferation, invasion, and migration capacities of hematologic malignancies. Therefore, this review may contribute novel insights to our understanding of the prospective therapeutic significance of H2S and its donors within the realm of hematologic malignancies.

Hydrogen sulfide supplementation as a potential treatment for primary mitochondrial diseases

Primary mitochondrial diseases (PMD) are amongst the most common inborn errors of metabolism causing fatal outcomes within the first decade of life. With marked heterogeneity in both inheritance patterns and physiological manifestations, these conditions present distinct challenges for targeted drug therapy, where effective therapeutic countermeasures remain elusive within the clinic. Hydrogen sulfide (H2S)-based therapeutics may offer a new option for patient treatment, having been proposed as a conserved mitochondrial substrate and post-translational regulator across species, displaying therapeutic effects in age-related mitochondrial dysfunction and neurodegenerative models of mitochondrial disease. H2S can stimulate mitochondrial respiration at sites downstream of common PMD-defective subunits, augmenting energy production, mitochondrial function and reducing cell death. Here, we highlight the primary signalling mechanisms of H2S in mitochondria relevant for PMD and outline key cytoprotective proteins/pathways amenable to post-translational restoration via H2S-mediated persulfidation. The mechanisms proposed here, combined with the advent of potent mitochondria-targeted sulfide delivery molecules, could provide a framework for H2S as a countermeasure for PMD disease progression.

Natural H2S-donors: A new pharmacological opportunity for the management of overweight and obesity

The prevalence of overweight and obesity has progressively increased in the last few years, becoming a real threat to healthcare systems. To date, the clinical management of body weight gain is an unmet medical need, as there are few approved anti-obesity drugs and most require an extensive monitoring and vigilance due to risk of adverse effects and poor patient adherence/persistence. Growing evidence has shown that the gasotransmitter hydrogen sulfide (H2S) and, therefore, H2S-donors could have a central role in the prevention and treatment of overweight/obesity. The main natural sources of H2S-donors are plants from the Alliaceae (garlic and onion), Brassicaceae (e.g., broccoli, cabbage, and wasabi), and Moringaceae botanical families. In particular, polysulfides and isothiocyanates, which slowly release H2S, derive from the hydrolysis of alliin from Alliaceae and glucosinolates from Brassicaceae/Moringaceae, respectively. In this review, we describe the emerging role of endogenous H2S in regulating adipose tissue function and the potential efficacy of natural H2S-donors in animal models of overweight/obesity, with a final focus on the preliminary results from clinical trials. We conclude that organosulfur-containing plants and their extracts could be used before or in combination with conventional anti-obesity agents to improve treatment efficacy and reduce inflammation in obesogenic conditions. However, further high-quality studies are needed to firmly establish their clinical efficacy.

Chronic Exposure to Arsenic and Fluoride Starting at Gestation Alters Liver Mitochondrial Protein Expression and Induces Early Onset of Liver Fibrosis in Male Mouse Offspring

The presence of arsenic (As) and fluoride (F-) in drinking water is of concern due to the enormous number of individuals exposed to this condition worldwide. Studies in cultured cells and animal models have shown that As- or F-induced hepatotoxicity is primarily associated with redox disturbance and altered mitochondrial homeostasis. To explore the hepatotoxic effects of chronic combined exposure to As and F- in drinking water, pregnant CD-1 mice were exposed to 2 mg/L As (sodium arsenite) and/or 25 mg/L F- (sodium fluoride). The male offspring continued the exposure treatment up to 30 (P30) or 90 (P90) postnatal days. GSH levels, cysteine synthesis enzyme activities, and cysteine transporter levels were investigated in liver homogenates, as well as the expression of biomarkers of ferroptosis and mitochondrial biogenesis-related proteins. Serum transaminase levels and Hematoxylin-Eosin and Masson trichrome-stained liver tissue slices were examined. Combined exposure at P30 significantly reduced GSH levels and the mitochondrial transcription factor A (TFAM) expression while increasing lipid peroxidation, free Fe 2+, p53 expression, and serum ALT activity. At P90, the upregulation of cysteine uptake and synthesis was associated with a recovery of GSH levels. Nevertheless, the downregulation of TFAM continued and was now associated with a downstream inhibition of the expression of MT-CO2 and reduced levels of mtDNA and fibrotic liver damage. Our experimental approach using human-relevant doses gives evidence of the increased risk for early liver damage associated with elevated levels of As and F- in the diet during intrauterine and postnatal period.

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.

Effects of H2S-donor ascorbic acid derivative and ischemia/reperfusion-induced injury in isolated rat hearts

Hydrogen sulfide (H2S), a gasotransmitter, plays a crucial role in vasorelaxation, anti-inflammatory processes and mitigating myocardial ischemia/reperfusion-induced injury by regulating various signaling processes. We designed a water soluble H2S-releasing ascorbic acid derivative, BM-164, to combine the beneficial cardiovascular and anti-inflammatory effects of H2S with the excellent water solubility and antioxidant properties of ascorbic acid. DPPH antioxidant assay revealed that the antioxidant activity of BM-164 in the presence of a myocardial tissue homogenate (extract) increased continuously over the 120 min test interval due to the continuous release of H2S from BM-164. The cytotoxicity of BM-164 was tested by MTT assay on H9c2 cells, which resulted in no cytotoxic effect at concentrations of 10 to 30 μM. The possible beneficial effects of BM-164 (30 µM) was examined in isolated 'Langendorff' rat hearts. The incidence of ventricular fibrillation (VF) was significantly reduced from its control value of 79 % to 31 % in the BM-164 treated group, and the infarct size was also diminished from the control value of 28 % to 14 % in the BM-164 treated group. However, coronary flow (CF) and heart rate (HR) values in the BM-164 treated group did not show significantly different levels in comparison with the drug-free control, although a non-significant recovery in both CF and HR was observed at each time point. We attempted to reveal the mechanism of action of BM-164, focusing on the processes of autophagy and apoptosis. The expression of key autophagic and apoptotic markers in isolated rat hearts were detected by Western blot analysis. All the examined autophagy-related proteins showed increased expression levels in the BM-164 treated group in comparison to the drug-free control and/or ascorbic acid treated groups, while the changes in the expression of apoptotic markers were not obvious. In conclusion, the designed water soluble H2S releasing ascorbic acid derivative, BM-164, showed better cardiac protection against ischemia/reperfusion-induced injury compared to the untreated and ascorbic acid treated hearts, respectively.

Endothelial H2S-AMPK dysfunction upregulates the angiocrine factor PAI-1 and contributes to lung fibrosis

Dysfunction of the vascular angiocrine system is critically involved in regenerative defects and fibrosis of injured organs. Previous studies have identified various angiocrine factors and found that risk factors such as aging and metabolic disorders can disturb the vascular angiocrine system in fibrotic organs. One existing key gap is what sense the fibrotic risk to modulate the vascular angiocrine system in organ fibrosis. Here, using human and mouse data, we discovered that the metabolic pathway hydrogen sulfide (H2S)-AMP-activated protein kinase (AMPK) is a sensor of fibrotic stress and serves as a key mechanism upregulating the angiocrine factor plasminogen activator inhibitor-1 (PAI-1) in endothelial cells to participate in lung fibrosis. Activation of the metabolic sensor AMPK was inhibited in endothelial cells of fibrotic lungs, and AMPK inactivation was correlated with enriched fibrotic signature and reduced lung functions in humans. The inactivation of endothelial AMPK accelerated lung fibrosis in mice, while the activation of endothelial AMPK with metformin alleviated lung fibrosis. In fibrotic lungs, endothelial AMPK inactivation led to YAP activation and overexpression of the angiocrine factor PAI-1, which was positively correlated with the fibrotic signature in human fibrotic lungs and inhibition of PAI-1 with Tiplaxtinin mitigated lung fibrosis. Further study identified that the deficiency of the antioxidative gas metabolite H2S accounted for the inactivation of AMPK and activation of YAP-PAI-1 signaling in endothelial cells of fibrotic lungs. H2S deficiency was involved in human lung fibrosis and H2S supplement reversed mouse lung fibrosis in an endothelial AMPK-dependent manner. These findings provide new insight into the mechanism underlying the deregulation of the vascular angiocrine system in fibrotic organs.

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.

The potential role of hydrogen sulfide in cancer cell apoptosis

For a long time, hydrogen sulfide (H2S) has been considered a toxic compound, but recent studies have found that H2S is the third gaseous signaling molecule which plays a vital role in physiological and pathological conditions. Currently, a large number of studies have shown that H2S mediates apoptosis through multiple signaling pathways to participate in cancer occurrence and development, for example, PI3K/Akt/mTOR and MAPK signaling pathways. Therefore, the regulation of the production and metabolism of H2S to mediate the apoptotic process of cancer cells may improve the effectiveness of cancer treatment. In this review, the role and mechanism of H2S in cancer cell apoptosis in mammals are summarized.

Peptide-based probe for colorimetric and fluorescent detection of Cu2+ and S2- in environmental and biological systems

Pollution caused by Copper and hydrogen sulfide pollution has severe adverse effects on the environment and organisms. Real-time, fast and accurate monitoring of Cu2+ and S2- faces serious challenges. In this study, we designed a novel biosensor and synthesized it by mimicking the structure of the main Cu(II)-binding site on bovine serum albumin. As a peptide-based sensor, FGGH (FITC-Gly-Gly-His-NH2) can perform the sequential detection of Cu2+ and S2- by fluorescence and colorimetry. The high water solubility and selectivity make it suitable for monitoring Cu2+ and S2- in environmental water samples with high sensitivity; its limit of detection (LOD) is as low as 1.42 nM for Cu2+ and 22.2 nM for S2-. The paper-based sensing platform of this probe was found to be a promising tool for the on-site visualization of real-time quantitative analysis of Cu2+ and S2- due to its rapid response and recyclable detection characteristics. Additionally, FGGH was successfully used to image Cu2+ and S2- in living cells and zebrafish models with adequate fluorescence stability and low cytotoxicity, providing the first visual evidence of the effect of the interactions between Cu2+ and S2- on the redox homeostasis of organisms.

S-Allyl-L-Cysteine Affects Cell Proliferation and Expression of H2S-Synthetizing Enzymes in MCF-7 and MDA-MB-231 Adenocarcinoma Cell Lines

S-allyl-L-cysteine (SAC) is a sulfur compound present in fresh garlic. The reference literature describes its anticancer, antioxidant and neuroprotective effects. Breast cancer is infamously known as one of the most commonly diagnosed malignancies among women worldwide. Its morbidity and mortality make it reasonable to complete and expand knowledge on this cancer's characteristics. Hydrogen sulfide (H2S) and its naturally occurring donors are well-known investigation subjects for diverse therapeutic purposes. This study was conducted to investigate the SAC antiproliferative potential and effect on three enzymes involved in H2S metabolism: 3-mercaptopyruvate sulfurtransferase (MPST), cystathionine γ-lyase (CTH), and cystathionine β-synthase (CBS). We chose the in vitro cellular model of human breast adenocarcinomas: MCF-7 and MDA-MB-231. The expression of enzymes after 2, 4, 6, 8, and 24 h incubation with 2.24 mM, 3.37 mM, and 4.50 mM SAC concentrations was examined. The number of living cells was determined by the MTS assay. Changes in cellular plasma membrane integrity were measured by the LDH test. Expression changes at the protein level were analyzed using Western blot. A significant decrease in viable cells was registered for MCF-7 cells after all incubation times upon 4.50 mM SAC exposure, and after 6 and 24 h only in MDA-MB-231 upon 4.50 mM SAC. In both cell lines, the MPST gene expression significantly increased after the 24 h incubation with 4.50 mM SAC. S-allyl-L-cysteine had opposite effects on changes in CTH and CBS expression in both cell lines. In our research model, we confirmed the antiproliferative potential of SAC and concluded that our studies provided current information about the increase in MPST gene expression mediated by S-allyl-L-cysteine in the adenocarcinoma in vitro cellular model for the MCF-7 and MDA-MB-231 cell lines. Further investigation of this in vitro model can bring useful information regarding sulfur enzyme metabolism of breast adenocarcinoma and regulating its activity and expression (gene silencing) in anticancer therapy.

Hydrogen sulfide responsive nanoplatforms: Novel gas responsive drug delivery carriers for biomedical applications

Hydrogen sulfide (H2S) is a toxic, essential gas used in various biological and physical processes and has been the subject of many targeted studies on its role as a new gas transmitter. These studies have mainly focused on the production and pharmacological side effects caused by H2S. Therefore, effective strategies to remove H2S has become a key research topic. Furthermore, the development of novel nanoplatforms has provided new tools for the targeted removal of H2S. This paper was performed to review the association between H2S and disease, related H2S inhibitory drugs, as well as H2S responsive nanoplatforms (HRNs). This review first analyzed the role of H2S in multiple tissues and conditions. Second, common drugs used to eliminate H2S, as well as their potential for combination with anticancer agents, were summarized. Not only the existing studies on HRNs, but also the inhibition H2S combined with different therapeutic methods were both sorted out in this review. Furthermore, this review provided in-depth analysis of the potential of HRNs about treatment or detection in detail. Finally, potential challenges of HRNs were proposed. This study demonstrates the excellent potential of HRNs for biomedical applications.

Role of circadian clock system in the mitochondrial trans-sulfuration pathway and tissue remodeling

Previous studies from our laboratory revealed that the gaseous molecule hydrogen sulfide (H2S), a metabolic product of epigenetics, involves trans-sulfuration pathway for ensuring metabolism and clearance of homocysteine (Hcy) from body, thereby mitigating the skeletal muscle's pathological remodeling. Although the master circadian clock regulator that is known as brain and muscle aryl hydrocarbon receptor nuclear translocator like protein 1 (i.e., BMAL 1) is associated with S-adenosylhomocysteine hydrolase (SAHH) and Hcy metabolism but how trans-sulfuration pathway is influenced by the circadian clock remains unexplored. We hypothesize that alterations in the functioning of circadian clock during sleep and wake cycle affect skeletal muscle's biology. To test this hypothesis, we measured serum matrix metalloproteinase (MMP) activities using gelatin gels for analyzing the MMP-2 and MMP-9. Further, employing casein gels, we also studied MMP-13 that is known to be influenced by the growth arrest and DNA damage-45 (GADD45) protein during sleep and wake cycle. The wild type and cystathionine β synthase-deficient (CBS-/+) mice strains were treated with H2S and subjected to measurement of trans-sulfuration factors from skeletal muscle tissues. The results suggested highly robust activation of MMPs in the wake mice versus sleep mice, which appears somewhat akin to the "1-carbon metabolic dysregulation", which takes place during remodeling of extracellular matrix during muscular dystrophy. Interestingly, the levels of trans-sulfuration factors such as CBS, cystathionine γ lyase (CSE), methyl tetrahydrofolate reductase (MTHFR), phosphatidylethanolamine N-methyltransferase (PEMT), and Hcy-protein bound paraoxonase 1 (PON1) were attenuated in CBS-/+ mice. However, treatment with H2S mitigated the attenuation of the trans-sulfuration pathway. In addition, levels of mitochondrial peroxisome proliferator-activated receptor-gamma coactivator 1-α (PGC 1-α) and mitofusin-2 (MFN-2) were significantly improved by H2S intervention. Our findings suggest participation of the circadian clock in trans-sulfuration pathway that affects skeletal muscle remodeling and mitochondrial regeneration.

Dynamic Changes and Effects of H2S, IGF-1, and GH in the Traumatic Brain Injury

The aim of this study was to examine the expression changes of H2S, IGF-1, and GH in traumatic brain injury (TBI) patients and to detect their neuroprotective functions after TBI. In this study, we first collected cerebrospinal fluid (CSF) and plasma from TBI patients at different times after injury and evaluated the concentrations of H2S, IGF-1, and GH. In vitro studies were using the scratch-induced injury model and cell-cell interaction model (HT22 hippocampal neurons co-cultured with LPS-induced BV2 microglia cells). In vivo studies were using the controlled cortical impact (CCI) model in mice. Cell viability was assessed by CCK-8 assay. Pro-inflammatory cytokines expression was determined by qRT-PCR, ELISA, and nitric oxide production. Western blot was performed to assess the expression of CBS, CSE, IGF-1, and GHRH. Moreover, the recovery of TBI mice was evaluated for behavioral function by applying the modified Neurological Severity Score (mNSS), the Rotarod test, and the Morris water maze. We discovered that serum H2S, CSF H2S, and serum IGF-1 concentrations were all adversely associated with the severity of the TBI, while the concentrations of IGF-1 and GH in CSF and GH in the serum were all positively related to TBI severity. Experiments in vitro and in vivo indicated that treatment with NaHS (H2S donor), IGF-1, and MR-409 (GHRH agonist) showed protective effects after TBI. This study gives novel information on the functions of H2S, IGF-1, and GH in TBI.

Choline induced cardiac dysfunction by inhibiting the production of endogenous hydrogen sulfide in spontaneously hypertensive rats

To investigate the exact effects of dietary choline on hypertensive heart disease (HHD) and explore the potential mechanisms, male spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) were randomly divided into five groups as follows: WKY group, WKY + Choline group, SHR group, SHR + Choline group, and SHR + Choline + NaHS group. In choline treatment groups, rats were fed with 1.3% (w/v) choline in the drinking water for 3 months. The rats in the SHR + Choline + NaHS group were intraperitoneally injected with NaHS (100 micromol/kg/day, a hydrogen sulfide (H2S) donor) for 3 months. After 3 months, left ventricular ejection fraction (LVEF) and fractional shortening (LVFS), the indicators of cardiac function measured by echocardiography, were increased significantly in SHR as compared to WKY, although there was no significant difference in collagen volumes and Bax/Bcl-2 ratio between the two groups, indicating the early stage of cardiac hypertrophy. There was a significant decrease in LVEF and LVFS and an increase in collagen volumes and Bax/Bcl-2 ratio in SHR fed with choline, meanwhile, plasma H2S levels were significantly decreased significantly in SHR fed with choline accompanying by the decrease of cystathionine-gamma-lyase (CSE) activity. Three months of NaHS significantly increased plasma H2S levels, ameliorated cardiac dysfunction and inhibited cardiac fibrosis and apoptosis in SHR fed with choline. In conclusion, choline aggravated cardiac dysfunction in HHD through inhibiting the production of endogenous H2S, which was reversed by supplementation of exogenous H2S donor.

Exploring the Role of Mitochondrial Hydrogen Sulfide in Maintaining Polarity and mtDNA Integrity with a Multichannel Fluorescent Probe

Abnormal mitochondrial state has been implicated in the pathogenesis of various diseases including neurodegenerative disorders, myopathies, cardiovascular diseases, and cancers. Assessing mitochondrial functionality can be achieved by monitoring alterations in mitochondrial polarity and mitochondrial DNA (mtDNA) integrity, which serve as valuable biomarkers. Hydrogen sulfide (H2S), a gaseous signaling molecule, plays a regulatory role in mitochondrial respiratory chain activity, ATP synthesis, and calcium ion balance, thereby influencing cellular metabolism and signal transduction. Investigating the interplay between mitochondrial H2S, polarity, and mtDNA can enhance our understanding of the underlying regulatory mechanisms involved in H2S-mediated mitochondrial functions. To address this, we designed a mitochondria-targeted multichannel fluorescent probe, HNA, capable of cascaded detection of H2S and polarity, as well as parallel detection of mtDNA. The probe exhibited a significant turn-on response to H2S, emitting at approximately 604 nm, while the product HNAP demonstrated high sensitivity to polarity within the wavelength range of 526-591 nm. Additionally, the probe was able to bind to DNA, resulting in an enhanced long-wave emission at 668 nm. Facilitated by HNA, our study provides novel insights into the role of mitochondrial H2S in maintaining mitochondrial polarity and validates its protective effect on mtDNA through antioxidative mechanisms. Overall, this work proposes a potential therapeutic strategy for modulating the inflammatory process in mitochondrial-related diseases.

A role for the cystathionine-β-synthase /H2S axis in astrocyte dysfunction in the aging brain

Astrocytic dysfunction is central to age-related neurodegenerative diseases. However, the mechanisms leading to astrocytic dysfunction are not well understood. We identify that among the diverse cellular constituents of the brain, murine and human astrocytes are enriched in the expression of CBS. Depleting CBS in astrocytes causes mitochondrial dysfunction, increases the production of reactive oxygen species (ROS) and decreases cellular bioenergetics that can be partially rescued by exogenous H2S supplementation or by re-expressing CBS. Conversely, the CBS/H2S axis, associated protein persulfidation and proliferation are decreased in astrocytes upon oxidative stress which can be rescued by exogenous H2S supplementation. Here we reveal that in the aging brain, the CBS/H2S axis is downregulated leading to decreased protein persulfidation, together augmenting oxidative stress. Our findings uncover an important protective role of the CBS/H2S axis in astrocytes that may be disrupted in the aged brain.

Reactive oxygen species (ROS) scavenging biomaterials for anti-inflammatory diseases: from mechanism to therapy

Inflammation is a fundamental defensive response to harmful stimuli, but the overactivation of inflammatory responses is associated with most human diseases. Reactive oxygen species (ROS) are a class of chemicals that are generated after the incomplete reduction of molecular oxygen. At moderate levels, ROS function as critical signaling molecules in the modulation of various physiological functions, including inflammatory responses. However, at excessive levels, ROS exert toxic effects and directly oxidize biological macromolecules, such as proteins, nucleic acids and lipids, further exacerbating the development of inflammatory responses and causing various inflammatory diseases. Therefore, designing and manufacturing biomaterials that scavenge ROS has emerged an important approach for restoring ROS homeostasis, limiting inflammatory responses and protecting the host against damage. This review systematically outlines the dynamic balance of ROS production and clearance under physiological conditions. We focus on the mechanisms by which ROS regulate cell signaling proteins and how these cell signaling proteins further affect inflammation. Furthermore, we discuss the use of potential and currently available-biomaterials that scavenge ROS, including agents that were engineered to reduce ROS levels by blocking ROS generation, directly chemically reacting with ROS, or catalytically accelerating ROS clearance, in the treatment of inflammatory diseases. Finally, we evaluate the challenges and prospects for the controlled production and material design of ROS scavenging biomaterials.

Chemistry of Hydrogen Sulfide-Pathological and Physiological Functions in Mammalian Cells

Hydrogen sulfide (H2S) was recognized as a gaseous signaling molecule, similar to nitric oxide (-NO) and carbon monoxide (CO). The aim of this review is to provide an overview of the formation of hydrogen sulfide (H2S) in the human body. H2S is synthesized by enzymatic processes involving cysteine and several enzymes, including cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), cysteine aminotransferase (CAT), 3-mercaptopyruvate sulfurtransferase (3MST) and D-amino acid oxidase (DAO). The physiological and pathological effects of hydrogen sulfide (H2S) on various systems in the human body have led to extensive research efforts to develop appropriate methods to deliver H2S under conditions that mimic physiological settings and respond to various stimuli. These functions span a wide spectrum, ranging from effects on the endocrine system and cellular lifespan to protection of liver and kidney function. The exact physiological and hazardous thresholds of hydrogen sulfide (H2S) in the human body are currently not well understood and need to be researched in depth. This article provides an overview of the physiological significance of H2S in the human body. It highlights the various sources of H2S production in different situations and examines existing techniques for detecting this gas.

Construction of a novel chitosan-based macromolecular nanoprobe for specific fluorescent detection of H2S in live animals

H2S is one of the signal molecules in live organisms and a poisonous gas, which is closely related to our life. The traditional synthetic small molecular organic probes often have the disadvantages of low biocompatibility. In this paper, a fluorescent nanoprobe for detecting H2S in live organisms was constructed based on chitosan. The structure of CH-CN was characterized by infrared spectroscopy, nuclear magnetic resonance, x-ray photoelectron spectroscopy (XPS), XRD and scanning electron microscope (SEM). In the presence of Na2S, the fluorescence intensity at 560 nm was significantly enhanced, and showed high selectivity and sensitivity toward H2S. Based on the good fluorescence response of CH-CN, the probe was also successfully applied to H2S imaging in HepG2 cells and zebrafish. These experimental results indicate that the probe has lower cytotoxicity and excellent stability. The present research shows a typical example of construction of chitosan-based macromolecular fluorescent materials and their bio-imaging application.

Precise Spatiotemporal Identification of Mitochondrial H2S Fluctuations through Exploiting an On-Demand Photoactivated Probe

Various signal molecules participate in complex biological processes in mitochondria. However, most currently available probes have problems in elucidating the functions of these active species in mitochondria due to the inability to light up these probes exclusively at the desired mitochondrial location, thereby compromising the specificity and accuracy. In this study, we present an on-demand photoactivation approach to the molecular design of optimized probes for precise spatiotemporal identification of mitochondrial H2S fluctuations. The designed probe with native yellow fluorescence can monitor the process into mitochondria but maintains nonfluorescent response to H2S during cellular delivery, providing the accurate timing of accumulation in mitochondria. On-demand photoactivation exclusively at the desired mitochondrial location affords a significant aggregation-enhanced and emissive response to H2S with lighting up red fluorescence at 690 nm, which is the only way to get such an emissive phenomenon and greatly improves the specificity and accuracy of targeting mitochondrial H2S. By using this photocontrolled fluorescence responsiveness to H2S, precise spatiotemporal identification of mitochondrial H2S fluctuations is successfully performed. Our work could facilitate advances toward interrogating the physiological and pathological consequences of mitochondrial H2S in various biological events.

Recent advances in the role of endogenous hydrogen sulphide in cancer cells

Hydrogen sulphide (H2 S) is a gaseous neurotransmitter that can be self-synthesized by living organisms. With the deepening of research, the pathophysiological mechanisms of endogenous H2 S in cancer have been increasingly elucidated: (1) promote angiogenesis, (2) stimulate cell bioenergetics, (3) promote migration and proliferation thereby invasion, (4) inhibit apoptosis and (5) activate abnormal cell cycle. However, the increasing H2 S levels via exogenous sources show the opposite trend. This phenomenon can be explained by the bell-shaped pharmacological model of H2 S, that is, the production of endogenous (low concentration) H2 S promotes tumour growth while the exogenous (high concentration) H2 S inhibits tumour growth. Here, we review the impact of endogenous H2 S synthesis and metabolism on tumour progression, summarize the mechanism of action of H2 S in tumour growth, and discuss the possibility of H2 S as a potential target for tumour treatment.

A mitochondria-targeted chemiluminescent probe for detection of hydrogen sulfide in cancer cells, human serum and in vivo

Hydrogen sulfide (H2S) as a critical messenger molecule plays vital roles in regular cell function. However, abnormal levels of H2S, especially mitochondrial H2S, are directly correlated with the formation of pathological states including neurodegenerative diseases, cardiovascular disorders, and cancer. Thus, monitoring fluxes of mitochondrial H2S concentrations both in vitro and in vivo with high selectivity and sensitivity is crucial. In this direction, herein we developed the first ever example of a mitochondria-targeted and H2S-responsive new generation 1,2-dioxetane-based chemiluminescent probe (MCH). Chemiluminescent probes offer unique advantages compared to conventional fluorophores as they do not require external light irradiation to emit light. MCH exhibited a dramatic turn-on response in its luminescence signal upon reacting with H2S with high selectivity. It was used to detect H2S activity in different biological systems ranging from cancerous cells to human serum and tumor-bearing mice. We anticipate that MCH will pave the way for development of new organelle-targeted chemiluminescence agents towards imaging of different analytes in various biological models.

Reactive Oxygen Species: A Crosslink between Plant and Human Eukaryotic Cell Systems

Reactive oxygen species (ROS) are important regulating factors that play a dual role in plant and human cells. As the first messenger response in organisms, ROS coordinate signals in growth, development, and metabolic activity pathways. They also can act as an alarm mechanism, triggering cellular responses to harmful stimuli. However, excess ROS cause oxidative stress-related damage and oxidize organic substances, leading to cellular malfunctions. This review summarizes the current research status and mechanisms of ROS in plant and human eukaryotic cells, highlighting the differences and similarities between the two and elucidating their interactions with other reactive substances and ROS. Based on the similar regulatory and metabolic ROS pathways in the two kingdoms, this review proposes future developments that can provide opportunities to develop novel strategies for treating human diseases or creating greater agricultural value.

Regulation of Mitochondrial Respiration by Hydrogen Sulfide

Hydrogen sulfide (H2S), the third gasotransmitter, has positive roles in animals and plants. Mitochondria are the source and the target of H2S and the regulatory hub in metabolism, stress, and disease. Mitochondrial bioenergetics is a vital process that produces ATP and provides energy to support the physiological and biochemical processes. H2S regulates mitochondrial bioenergetic functions and mitochondrial oxidative phosphorylation. The article summarizes the recent knowledge of the chemical and biological characteristics, the mitochondrial biosynthesis of H2S, and the regulatory effects of H2S on the tricarboxylic acid cycle and the mitochondrial respiratory chain complexes. The roles of H2S on the tricarboxylic acid cycle and mitochondrial respiratory complexes in mammals have been widely studied. The biological function of H2S is now a hot topic in plants. Mitochondria are also vital organelles regulating plant processes. The regulation of H2S in plant mitochondrial functions is gaining more and more attention. This paper mainly summarizes the current knowledge on the regulatory effects of H2S on the tricarboxylic acid cycle (TCA) and the mitochondrial respiratory chain. A study of the roles of H2S in mitochondrial respiration in plants to elucidate the botanical function of H2S in plants would be highly desirable.

Mackinawite nanozymes as reactive oxygen species scavengers for acute kidney injury alleviation

BACKGROUND

Iron sulfide nanomaterials have been successfully employed as therapeutic agents for bacterial infection therapy and catalytic-ferroptosis synergistic tumor therapy due to their unique structures, physiochemical properties, and biocompatibility. However, biomedical research and understanding of the biological functions of iron sulfides are insufficient, and how iron sulfide nanomaterials affect reactive oxygen species (ROS) in diseases remains unknown. Acute kidney injury (AKI) is associated with high levels of ROS, and therefore nanomedicine-mediated antioxidant therapy has emerged as a novel strategy for its alleviation.

RESULTS

Here, mackinawite nanozymes were synthesized from glutathione (GSH) and iron ions (Fe3+) (denoted as GFeSNs) using a hydrothermal method, and then evaluated as ROS scavengers for ROS-related AKI treatment. GFeSNs showed broad-spectrum ROS scavenging ability through synergistic interactions of multiple enzymes-like and hydrogen polysulfide-releasing properties. Furthermore, both in vitro and in vivo experiments demonstrated that GFeSNs exhibited outstanding cytoprotective effects against ROS-induced damage at extremely low doses and significantly improved treatment outcomes in AKI.

CONCLUSIONS

Given the synergetic antioxidant properties and high biocompatibility, GFeSNs exhibit great potential for the treatment of AKI and other ROS-associated diseases.

Hydrogen Sulfide Prevents LPS-Induced Depression-like Behavior through the Suppression of NLRP3 Inflammasome and Pyroptosis and the Improvement of Mitochondrial Function in the Hippocampus of Mice

Hydrogen sulfide (H2S) has been implicated to have antidepressive effects. We sought to investigate the prevention effects of H2S donor NaHS on depression-like behavior induced by lipopolysaccharide (LPS) in mice and its potential mechanisms. Sucrose preference, force swimming, open field, and elevate zero maze were used to evaluate depression-like behavior. NF-κB and NLRP3 inflammasome activation and mitochondrial function in the hippocampus were determined. It was found that depression-like behavior induced by LPS was prevented by NaHS pretreatment. LPS caused NF-κB and NLRP3 inflammasome activation in the hippocampus as evidenced by increased phosphorylated-p65 levels and increased NLRP3, ASC, caspase-1, and mature IL-1β levels in the hippocampus, which were also blocked by NaHS. LPS increased GSDMD-N levels and TUNEL-positive cells in the hippocampus, which was prevented by NaHS. Abnormal mitochondrial morphology in the hippocampus was found in LPS-treated mice. Mitochondrial membrane potential and ATP production were reduced, and ROS production was increased in the hippocampus of LPS-treated mice. NaHS pretreatment improved impaired mitochondrial morphology and increased membrane potential and ATP production and reduced ROS production in the hippocampus of LPS-treated mice. Our data indicate that H2S prevents LPS-induced depression-like behaviors by inhibiting NLRP3 inflammasome activation and pyroptosis and improving mitochondrial function in the hippocampus.

Targeting Homocysteine and Hydrogen Sulfide Balance as Future Therapeutics in Cancer Treatment

A high level of homocysteine (Hcy) is associated with oxidative/ER stress, apoptosis, and impairment of angiogenesis, whereas hydrogen sulfide (H2S) has been found to reverse this condition. Recent studies have shown that cancer cells need to produce a high level of endogenous H2S to maintain cell proliferation, growth, viability, and migration. However, any novel mechanism that targets this balance of Hcy and H2S production has yet to be discovered or exploited. Cells require homocysteine metabolism via the methionine cycle for nucleotide synthesis, methylation, and reductive metabolism, and this pathway supports the high proliferative rate of cancer cells. Although the methionine cycle favors cancer cells for their survival and growth, this metabolism produces a massive amount of toxic Hcy that somehow cancer cells handle very well. Recently, research showed specific pathways important for balancing the antioxidative defense through H2S production in cancer cells. This review discusses the relationship between Hcy metabolism and the antiapoptotic, antioxidative, anti-inflammatory, and angiogenic effects of H2S in different cancer types. It also summarizes the historical understanding of targeting antioxidative defense systems, angiogenesis, and other protective mechanisms of cancer cells and the role of H2S production in the genesis, progression, and metastasis of cancer. This review defines a nexus of diet and precision medicine in targeting the delicate antioxidative system of cancer and explores possible future therapeutics that could exploit the Hcy and H2S balance.

Beneficial Effects of Two Hydrogen Sulfide (H2S)-Releasing Derivatives of Dexamethasone with Antioxidant Activity on Atopic Dermatitis in Mice

Hydrogen sulfide (H₂S) is particularly produced in the skin, where it participates in the regulation of inflammation, pruritus, cytoprotection, scarring, and angiogenesis. In this study, we compared the effects of dexamethasone (Dex) with two H₂S-releasing Dex derivatives in a murine model of atopic dermatitis (AD) induced by topical application of 2,4-dinitrochlorobenzene (DNCB). After sensitization with DNCB, the animals were topically treated for five consecutive days with either the H₂S-releasing compounds 4-hydroxy-thiobenzamide (TBZ) and 5-(p-hydroxyphenyl)-1,2-dithione-3-thione (ADT-OH), Dex, or the derivatives Dex-TBZ or Dex-ADT. Topical treatment with equimolar doses of either Dex, Dex-TBZ, or Dex-ADT resulted in similar reductions in dermatitis score, scratching behavior, edema, eosinophilia, splenomegaly, and histological changes. In contrast with Dex, the H₂S-releasing derivatives prevented IL-4 elevation and oxidative modification of skin proteins. On an equimolar dose basis, Dex-TBZ, but not Dex-ADT, promoted the elevation of endogenous H₂S production and GPx activity. Neither Dex-TBZ nor Dex-ADT decreased GR activity or caused hyperglycemia, as observed with Dex treatment. We conclude that the presence of H₂S-releasing moieties in the Dex structure does not interfere with the anti-inflammatory effects of this corticosteroid and adds beneficial therapeutical actions to the parent compound.

Hydrogen sulfide functions as a micro-modulator bound at the copper active site of Cu/Zn-SOD to regulate the catalytic activity of the enzyme

The present study examines whether there is a mechanism beyond the current concept of post-translational modifications to regulate the function of a protein. A small gas molecule, hydrogen sulfide (H₂S), was found to bind at active-site copper of Cu/Zn-SOD using a series of methods including radiolabeled binding assay, X-ray absorption near-edge structure (XANES), and crystallography. Such an H₂S binding enhanced the electrostatic forces to guide the negatively charged substrate superoxide radicals to the catalytic copper ion, changed the geometry and energy of the frontier molecular orbitals of the active site, and subsequently facilitated the transfer of an electron from the superoxide radical to the catalytic copper ion and the breakage of the copper-His61 bridge. The physiological relevance of such an H₂S effect was also examined in both in vitro and in vivo models where the cardioprotective effects of H₂S were dependent on Cu/Zn-SOD.

Mitochondrial Integrity Is Critical in Right Heart Failure Development

Molecular processes underlying right ventricular (RV) dysfunction (RVD) and right heart failure (RHF) need to be understood to develop tailored therapies for the abatement of mortality of a growing patient population. Today, the armament to combat RHF is poor, despite the advancing identification of pathomechanistic processes. Mitochondrial dysfunction implying diminished energy yield, the enhanced release of reactive oxygen species, and inefficient substrate metabolism emerges as a potentially significant cardiomyocyte subcellular protagonist in RHF development. Dependent on the course of the disease, mitochondrial biogenesis, substrate utilization, redox balance, and oxidative phosphorylation are affected. The objective of this review is to comprehensively analyze the current knowledge on mitochondrial dysregulation in preclinical and clinical RVD and RHF and to decipher the relationship between mitochondrial processes and the functional aspects of the right ventricle (RV).

Talk to Me-Interplay between Mitochondria and Microbiota in Aging

The existence of mitochondria in eukaryotic host cells as a remnant of former microbial organisms has been widely accepted, as has their fundamental role in several diseases and physiological aging. In recent years, it has become clear that the health, aging, and life span of multicellular hosts are also highly dependent on the still-residing microbiota, e.g., those within the intestinal system. Due to the common evolutionary origin of mitochondria and these microbial commensals, it is intriguing to investigate if there might be a crosstalk based on preserved common properties. In the light of rising knowledge on the gut-brain axis, such crosstalk might severely affect brain homeostasis in aging, as neuronal tissue has a high energy demand and low tolerance for according functional decline. In this review, we summarize what is known about the impact of both mitochondria and the microbiome on the host's aging process and what is known about the aging of both entities. For a long time, bacteria were assumed to be immortal; however, recent evidence indicates their aging and similar observations have been made for mitochondria. Finally, we present pathways by which mitochondria are affected by microbiota and give information about therapeutic anti-aging approaches that are based on current knowledge.

Taurine linked with healthy aging

Reversing age-associated taurine loss improves mouse longevity and monkey health.

Long-Chain Acyl Coenzyme A Dehydrogenase, a Key Player in Metabolic Rewiring/Invasiveness in Experimental Tumors and Human Mesothelioma Cell Lines

Cross-species investigations of cancer invasiveness are a new approach that has already identified new biomarkers which are potentially useful for improving tumor diagnosis and prognosis in clinical medicine and veterinary science. In this study, we combined proteomic analysis of four experimental rat malignant mesothelioma (MM) tumors with analysis of ten patient-derived cell lines to identify common features associated with mitochondrial proteome rewiring. A comparison of significant abundance changes between invasive and non-invasive rat tumors gave a list of 433 proteins, including 26 proteins reported to be exclusively located in mitochondria. Next, we analyzed the differential expression of genes encoding the mitochondrial proteins of interest in five primary epithelioid and five primary sarcomatoid human MM cell lines; the most impressive increase was observed in the expression of the long-chain acyl coenzyme A dehydrogenase (ACADL). To evaluate the role of this enzyme in migration/invasiveness, two epithelioid and two sarcomatoid human MM cell lines derived from patients with the highest and lowest overall survival were studied. Interestingly, sarcomatoid vs. epithelioid cell lines were characterized by higher migration and fatty oxidation rates, in agreement with ACADL findings. These results suggest that evaluating mitochondrial proteins in MM specimens might identify tumors with higher invasiveness.

Sulfur-Containing Amino Acids, Hydrogen Sulfide, and Sulfur Compounds on Kidney Health and Disease

Hydrogen sulfide (H₂S) plays a decisive role in kidney health and disease. H₂S can ben synthesized via enzymatic and non-enzymatic pathways, as well as gut microbial origins. Kidney disease can originate in early life induced by various maternal insults throughout the process, namely renal programming. Sulfur-containing amino acids and sulfate are essential in normal pregnancy and fetal development. Dysregulated H₂S signaling behind renal programming is linked to deficient nitric oxide, oxidative stress, the aberrant renin-angiotensin-aldosterone system, and gut microbiota dysbiosis. In animal models of renal programming, treatment with sulfur-containing amino acids, N-acetylcysteine, H₂S donors, and organosulfur compounds during gestation and lactation could improve offspring's renal outcomes. In this review, we summarize current knowledge regarding sulfide/sulfate implicated in pregnancy and kidney development, current evidence supporting the interactions between H₂S signaling and underlying mechanisms of renal programming, and recent advances in the beneficial actions of sulfide-related interventions on the prevention of kidney disease. Modifying H₂S signaling is the novel therapeutic and preventive approach to reduce the global burden of kidney disease; however, more work is required to translate this into clinical practice.

The Fecal Microbiome in Quiescent Crohn's Disease with Persistent Gastrointestinal Symptoms Show Enrichment of Oral Microbes But Depletion of Butyrate and Indole Producers

Background and Aims

Even in the absence of inflammation, persistent symptoms in Crohn's disease (CD) are prevalent and negatively impact quality of life. We aimed to determine whether quiescent CD patients with persistent symptoms ( qCD+symptoms ) have changes in microbial structure and functional potential compared to those without symptoms ( qCD-symptoms ).

Methods

We performed a prospective multi-center observational study nested within the SPARC IBD study. CD patients were included if they had evidence of quiescent disease as defined by fecal calprotectin level < 150 mcg/g. Persistent symptoms were defined by the CD-PRO2 questionnaire. Active CD ( aCD ), diarrhea-predominant irritable bowel syndrome ( IBS-D ), and healthy controls ( HC ) were included as controls. Stool samples underwent whole genome shotgun metagenomic sequencing.

Results

A total of 424 patients were analyzed, including 39 qCD+symptoms, 274 qCD-symptoms, 21 aCD, 40 IBS-D, and 50 HC. Patients with qCD+symptoms had a less diverse microbiome, including significant reductions in Shannon diversity ( P <.001) and significant differences in microbial community structure ( P <.0001), compared with qCD-symptoms, IBS-D, and HC. Further, patients with qCD+symptoms showed significant enrichment of bacterial species that are normal inhabitants of the oral microbiome, including Klebsiella pneumoniae (q=.003) as well as depletion of important butyrate and indole producers, such as Eubacterium rectale (q=.001), Lachnospiraceae spp . (q<.0001), and Faecalibacterium prausnitzii (q<.0001), compared with qCD-symptoms. Finally, qCD+symptoms showed significant reductions in bacterial tnaA genes, which mediate tryptophan metabolism, as well as significant tnaA allelic variation, compared with qCD-symptoms.

Conclusion

The microbiome in patients with qCD+symptoms show significant changes in diversity, community profile, and composition compared with qCD-symptoms. Future studies will focus on the functional significance of these changes.

What You Need to Know

Background: Persistent symptoms in quiescent Crohn's disease (CD) are prevalent and lead to worse outcomes. While changes in the microbial community have been implicated, the mechanisms by which altered microbiota may lead to qCD+symptoms remain unclear.Findings: Quiescent CD patients with persistent symptoms demonstrated significant differences in microbial diversity and composition compared to those without persistent symptoms. Specifically, quiescent CD patients with persistent symptoms were enriched in bacterial species that are normal inhabitants of the oral microbiome but depleted in important butyrate and indole producers compared to those without persistent symptoms.Implications for Patient Care: Alterations in the gut microbiome may be a potential mediator of persistent symptoms in quiescent CD. Future studies will determine whether targeting these microbial changes may improve symptoms in quiescent CD.

Fast and slow releasing sulphide donors engender distinct transcriptomic alterations in Atlantic salmon hepatocytes

Hydrogen sulphide (H₂S) is a naturally occurring compound generated either endogenously or exogenously and serves both as a gaseous signalling molecule and an environmental toxicant. Though it has been extensively investigated in mammalian systems, the biological function of H₂S in teleost fish is poorly identified. Here we demonstrate how exogenous H₂S regulates cellular and molecular processes in Atlantic salmon (Salmo salar) using a primary hepatocyte culture as a model. We employed two forms of sulphide donors: the fast-releasing salt form, sodium hydrosulphide (NaHS) and the slow-releasing organic analogue, morpholin-4-ium 4-methoxyphenyl(morpholino) phosphinodithioate (GYY4137). Hepatocytes were exposed to either a low (LD, 20 µg/L) or high (HD, 100 µg/L) dose of the sulphide donors for 24 hrs, and the expression of key sulphide detoxification and antioxidant defence genes were quantified by qPCR. The key sulphide detoxification genes sulfite oxidase 1 (soux) and the sulfide: quinone oxidoreductase 1 and 2 (sqor) paralogs in salmon showed pronounced expression in the liver and likewise responsive to the sulphide donors in the hepatocyte culture. These genes were ubiquitously expressed in different organs of salmon as well. HD-GYY4137 upregulated the expression of antioxidant defence genes, particularly glutathione peroxidase, glutathione reductase and catalase, in the hepatocyte culture. To explore the influence of exposure duration, hepatocytes were exposed to the sulphide donors (i.e., LD versus HD) either transient (1h) or prolonged (24h). Prolonged but not transient exposure significantly reduced hepatocyte viability, and the effects were not dependent on concentration or form. The proliferative potential of the hepatocytes was only affected by prolonged NaHS exposure, and the impact was not concentration dependent. Microarray analysis revealed that GYY4137 caused more substantial transcriptomic changes than NaHS. Moreover, transcriptomic alterations were more marked following prolonged exposure. Genes involved in mitochondrial metabolism were downregulated by the sulphide donors, primarily in NaHS-exposed cells. Both sulphide donors influenced the immune functions of hepatocytes: genes involved in lymphocyte-mediated response were affected by NaHS, whereas inflammatory response was targeted by GYY4137. In summary, the two sulphide donors impacted the cellular and molecular processes of teleost hepatocytes, offering new insights into the mechanisms underlying H₂S interactions in fish.

Hydrogen sulfide alleviates heart failure with preserved ejection fraction in mice by targeting mitochondrial abnormalities via PGC-1α

AIM

Increasing evidence has proposed that mitochondrial abnormalities may be an important factor contributing to the development of heart failure with preserved ejection fraction (HFpEF). Hydrogen sulfide (H₂S) has been suggested to play a pivotal role in regulating mitochondrial function. Therefore, the present study was designed to explore the protective effect of H₂S on mitochondrial dysfunction in a multifactorial mouse model of HFpEF.

METHODS

Wild type, 8-week-old, male C57BL/6J mice or cardiomyocyte specific-Cse (Cystathionine γ-lyase, a major H₂S-producing enzyme) knockout mice (CSE^cko) were given high-fat diet (HFD) and l-NAME (an inhibitor of constitutive nitric oxide synthases) or standardized chow. After 4 weeks, mice were randomly administered with NaHS (a conventional H₂S donor), ZLN005 (a potent transcriptional activator of PGC-1α) or vehicle. After additional 4 weeks, echocardiogram and mitochondrial function were evaluated. Expression of PGC-1α, NRF1 and TFAM in cardiomyocytes was assayed by western blot.

RESULTS

Challenging with HFD and l-NAME in mice not only caused HFpEF but also inhibited the production of endogenous H₂S in a time-dependent manner. Meanwhile the expression of PGC-1α and mitochondrial function in cardiomyocytes were impaired. Supplementation with NaHS not only upregulated the expression of PGC-1α, NRF1 and TFAM in cardiomyocytes but also restored mitochondrial function and ultrastructure, conferring an obvious improvement in cardiac diastolic function. In contrast, cardiac deletion of CSE gene aggravated the inhibition of PGC-1α-NRF1-TFAM pathway, mitochondrial abnormalities and diastolic dysfunction. The deleterious effect observed in CSE^cko HFpEF mice was partially counteracted by pre-treatment with ZLN005 or supplementation with NaHS.

CONCLUSION

Our findings have demonstrated that H₂S ameliorates left ventricular diastolic dysfunction by restoring mitochondrial abnormalities via upregulating PGC-1α and its downstream targets NRF1 and TFAM, suggesting the therapeutic potential of H₂S supplementation in multifactorial HFpEF.

Amino acid metabolism regulated by lncRNAs: the propellant behind cancer metabolic reprogramming

Metabolic reprogramming is one of the main characteristics of cancer cells and plays pivotal role in the proliferation and survival of cancer cells. Amino acid is one of the key nutrients for cancer cells and many studies have focused on the regulation of amino acid metabolism, including the genetic alteration, epigenetic modification, transcription, translation and post-translational modification of key enzymes in amino acid metabolism. Long non-coding RNAs (lncRNAs) are composed of a heterogeneous group of RNAs with transcripts of more than 200 nucleotides in length. LncRNAs can bind to biological molecules such as DNA, RNA and protein, regulating the transcription, translation and post-translational modification of target genes. Now, the functions of lncRNAs in cancer metabolism have aroused great research interest and significant progress has been made. This review focuses on how lncRNAs participate in the reprogramming of amino acid metabolism in cancer cells, especially glutamine, serine, arginine, aspartate, cysteine metabolism. This will help us to better understand the regulatory mechanism of cancer metabolic reprogramming and provide new ideas for the development of anti-cancer drugs. Video Abstract.

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.

Near-Infrared Fluorescent Probe for Imaging Upregulated Hydrogen Sulfide Levels in Rice under Salt and Drought Stress

Hydrogen sulfide (H₂S) is a hazardous gas found in living organisms and is directly tied to our daily lives. Recent studies show that it plays a significant role in plant growth, development, and response to environmental stresses. However, few of the reported near-infrared (NIR) fluorescent probes have been applied to rice and deeply investigated the influence of the external environment on the biological molecules in its internal environment. Therefore, our team created BSZ-H₂S, which has the advantage of an emission wavelength of up to 720 nm with fast response, successfully applying it to cell and zebrafish imaging. More importantly, the probe detected H₂S in rice roots by in situ imaging in a facile manner and verified the existence of an upregulation process of H₂S in response to salt and drought stress. This work provides a concept for the intervention of external stresses in rice culture.

Hydrogen sulfide regulates SERCA2a SUMOylation by S-Sulfhydration of SENP1 to ameliorate cardiac systole-diastole function in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus that eventually progresses to heart failure. The sarco(endo)plasmic reticulum calcium ATPase 2a (SERCA2a), an important calcium pump in cardiomyocytes, is closely related to myocardial systolic-diastolic function. In mammalian cells, hydrogen sulfide (H₂S), as a second messenger, antioxidant, and sulfurizing agent, is involved in diverse biological processes. Despite the importance of H₂S for protection against DCM, the mechanisms remain poorly understood. The aim of the present study was to determine whether H₂S regulates intracellular calcium homeostasis by acting on SERCA2a to reduce cardiomyocyte apoptosis during DCM. Db/db mice were injected with NaHS for 18 weeks. Neonatal rat cardiomyocytes (NRCMs) were treated with high glucose, palmitate, oleate, and NaHS for 48 h. Compared to the NaHS-treated groups, in vivo and in vitro type 2 diabetic models both showed reduced intracellular H₂S content, reduced cystathionine γ-lyase (CSE) expression, impaired cardiac function, decreased SERCA2a expression and decreased SERCA2a activity, reduced SUMOylation of SERCA2a, increased sentrin-specific protease 1 (SENP1) expression, and disruption of calcium homeostasis leading to activation of the mitochondrial apoptosis pathway. Compared to the NaHS-treated type 2 diabetes cellular model, overexpression of SENP1 C683A reduced the S-sulfhydration of SENP1, reduced the SUMOylation of SERCA2a, reduced the increased expression and activity of SERCA2a, and induced mitochondrial apoptosis in cardiomyocytes. These results suggested that exogenous H₂S elevates SENP1 S-sulfhydration to increase SERCA2a SUMOylation, improve myocardial systolic-diastolic function, and decrease cardiomyocyte apoptosis in DCM.

Hydropersulfides (RSSH) attenuate doxorubicin-induced cardiotoxicity while boosting its anticancer action

Cardiotoxicity is a frequent and often lethal complication of doxorubicin (DOX)-based chemotherapy. Here, we report that hydropersulfides (RSSH) are the most effective reactive sulfur species in conferring protection against DOX-induced toxicity in H9c2 cardiac cells. Mechanistically, RSSH supplementation alleviates the DOX-evoked surge in reactive oxygen species (ROS), activating nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent pathways, thus boosting endogenous antioxidant defenses. Simultaneously, RSSH turns on peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a master regulator of mitochondrial function, while decreasing caspase-3 activity to inhibit apoptosis. Of note, we find that RSSH potentiate anticancer DOX effects in three different cancer cell lines, with evidence that suggests this occurs via induction of reductive stress. Indeed, cancer cells already exhibit much higher basal hydrogen sulfide (H2S), sulfane sulfur, and reducing equivalents compared to cardiac cells. Thus, RSSH may represent a new promising avenue to fend off DOX-induced cardiotoxicity while boosting its anticancer effects.

Hydrogen sulfide signaling in plants

SIGNIFICANCE

Hydrogen sulfide (H2S) is a multitasking potent regulator that facilitates plant growth, development, and responses to environmental stimuli.

RECENT ADVANCES

The important beneficial effects of H2S in various aspects of plant physiology aroused the interest of this chemical for agriculture. Protein cysteine persulfidation has been recognized as the main redox regulatory mechanism of H2S signaling. An increasing number of studies, including large-scale proteomic analyses and function characterizations, have revealed that H2S-mediated persulfidations directly regulate protein functions, altering downstream signaling in plants. To date, the importance of H2S-mediated persufidation in several abscisic acid signaling-controlling key proteins has been assessed as well as their role in stomatal movements, largely contributing to the understanding of the plant H2S-regulatory mechanism.

CRITICAL ISSUES

The molecular mechanisms of the H2S sensing and transduction in plants remain elusive. The correlation between H2S-mediated persulfidation with other oxidative posttranslational modifications of cysteines are still to be explored.

FUTURE DIRECTIONS

Implementation of advanced detection approaches for the spatiotemporal monitoring of H2S levels in cells and the current proteomic profiling strategies for the identification and quantification of the cysteine site-specific persulfidation will provide insight into the H2S signaling in plants.

Protein persulfidation: Rewiring the hydrogen sulfide signaling in cell stress response

The past few decades have witnessed significant progress in the discovery of hydrogen sulfide (H₂S) as a ubiquitous gaseous signaling molecule in mammalian physiology, akin to nitric oxide and carbon monoxide. As the third gasotransmitter, H₂S is now known to exert a wide range of physiological and cytoprotective functions in the biological systems. However, endogenous H₂S concentrations are usually low, and its potential biologic mechanisms responsible have not yet been fully clarified. Recently, a growing body of evidence has demonstrated that protein persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH) elicited by H₂S, is a fundamental mechanism of H₂S-mediated signaling pathways. Persulfidation, as a biological switch for protein function, plays an important role in the maintenance of cell homeostasis in response to various internal and external stress stimuli and is also implicated in numerous diseases, such as cardiovascular and neurodegenerative diseases and cancer. In this review, the biological significance of protein persulfidation by H₂S in cell stress response is reviewed providing a framework for understanding the multifaceted roles of H₂S. A mechanism-guided perspective can help open novel avenues for the exploitation of therapeutics based on H₂S-induced persulfidation in the context of diseases.

GYY4137-Derived Hydrogen Sulfide Donates Electrons to the Mitochondrial Electron Transport Chain via Sulfide: Quinone Oxidoreductase in Endothelial Cells

The protective effects of hydrogen sulphide (H2S) to limit oxidative injury and preserve mitochondrial function during sepsis, ischemia/reperfusion, and neurodegenerative diseases have prompted the development of soluble H2S-releasing compounds such as GYY4137. Yet, the effects of GYY4137 on the mitochondrial function of endothelial cells remain unclear, while this cell type comprises the first target cell after parenteral administration. Here, we specifically assessed whether human endothelial cells possess a functional sulfide:quinone oxidoreductase (SQOR), to oxidise GYY4137-released H2S within the mitochondria for electron donation to the electron transport chain. We demonstrate that H2S administration increases oxygen consumption by human umbilical vein endothelial cells (HUVECs), which does not occur in the SQOR-deficient cell line SH-SY5Y. GYY4137 releases H2S in HUVECs in a dose- and time-dependent fashion as quantified by oxygen consumption and confirmed by lead acetate assay, as well as AzMC fluorescence. Scavenging of intracellular H2S using zinc confirmed intracellular and intramitochondrial sulfur, which resulted in mitotoxic zinc sulfide (ZnS) precipitates. Together, GYY4137 increases intramitochondrial H2S and boosts oxygen consumption of endothelial cells, which is likely governed via the oxidation of H2S by SQOR. This mechanism in endothelial cells may be instrumental in regulating H2S levels in blood and organs but can also be exploited to quantify H2S release by soluble donors such as GYY4137 in living systems.

The effect of mitochondria-targeted slow hydrogen sulfide releasing donor AP39-treatment on airway inflammation

Mitochondrial dysfunction has been shown to contribute to the pathophysiology of airway diseases. Therefore, mitochondria are targeted in the development of new therapeutic approaches. Hydrogen sulfide (H₂S) has been shown to be involved in the pathophysiological processes of airway inflammation. We aimed to evaluate the effect of mitochondria-targeted slow H₂S releasing donor AP39 [(10-oxo-10-(4-(3-thioxo-3H-1,2-dithiol5yl)phenoxy)decyl)triphenylphosphoniumbromide)] on lipopolysaccharide (LPS)-induced airway inflammation in mice. LPS was applied to female Balb/c mice by intranasal (i.n.) route to induce airway inflammation and the subgroups of mice were treated with i.n. AP39 (250-1000 nmol/kg). 48 h after LPS administration airway reactivity was evaluated in vivo, then bronchoalveolar lavage (BAL) fluid and lungs were collected. LPS application led to bronchial hyperreactivity and neutrophil infiltration into the lung tissues along with increased TNF-α, IL-1β and IL-6 levels in BAL fluid. LPS also induced an increase in the rate of glycolysis, glycogenolysis and Krebs-cycle. AP39 treatment prevented the LPS-induced bronchial hyperreactivity and reversed the increase in TNF-α and IL-6 levels in BAL fluid. The increase in neutrophil numbers in BAL fluid was also prevented by AP39 treatment at the highest dose. Our results indicate that AP39 can prevent bronchial hyperreactivity and decrease airway inflammation. Targeting H₂S to the mitochondria may be a new therapeutic approach in airway inflammation.

CTH/MPST double ablation results in enhanced vasorelaxation and reduced blood pressure via upregulation of the eNOS/sGC pathway

Hydrogen sulfide (H₂S), a gasotransmitter with protective effects in the cardiovascular system, is endogenously generated by three main enzymatic pathways: cystathionine gamma lyase (CTH), cystathionine beta synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (MPST) enzymes. CTH and MPST are the predominant sources of H₂S in the heart and blood vessels, exhibiting distinct effects in the cardiovascular system. To better understand the impact of H₂S in cardiovascular homeostasis, we generated a double Cth/Mpst knockout (Cth/Mpst ^-/- ) mouse and characterized its cardiovascular phenotype. CTH/MPST-deficient mice were viable, fertile and exhibited no gross abnormalities. Lack of both CTH and MPST did not affect the levels of CBS and H₂S-degrading enzymes in the heart and the aorta. Cth/Mpst ^-/- mice also exhibited reduced systolic, diastolic and mean arterial blood pressure, and presented normal left ventricular structure and fraction. Aortic ring relaxation in response to exogenously applied H₂S was similar between the two genotypes. Interestingly, an enhanced endothelium-dependent relaxation to acetylcholine was observed in mice in which both enzymes were deleted. This paradoxical change was associated with upregulated levels of endothelial nitric oxide synthase (eNOS) and soluble guanylate cyclase (sGC) α1 and β1 subunits and increased NO-donor-induced vasorelaxation. Administration of a NOS-inhibitor, increased mean arterial blood pressure to a similar extent in wild-type and Cth/Mpst ^-/- mice. We conclude that chronic elimination of the two major H₂S sources in the cardiovascular system, leads to an adaptive upregulation of eNOS/sGC signaling, revealing novel ways through which H₂S affects the NO/cGMP pathway.

Hydrogen Sulfide Promotes Osteogenesis by Modulating Macrophage Polarization

Macrophages, a versatile subset of immune cells, are essential for successful bone repair. Hydrogen sulfide (H₂S) is a gasotransmitter associated with tissue development and repair. Emerging evidence demonstrates that H₂S is involved in bone formation under physiology condition and bone regeneration under pathology condition. However, whether hydrogen sulfide mediates osteogenesis by influencing macrophages is unknown. Here, we aimed to investigate the effects of hydrogen sulfide on macrophage polarization and the subsequent impact on bone regeneration. In the present study, we found that the H₂S-donor GYY4137 stimulated M0/M1 macrophages to express high level of CD-206 and IL-10 but decreased the levels of i-NOS and TNF-α in M1 macrophages. Furthermore, coculture of GYY4137-treated M0 macrophages with pro-osteoblastic MC3T3-E1 cells significantly increased the viability of the MC3T3-E1 cells. Importantly, the formation of mineralized particles in MC3T3-E1 cells was significantly promoted following coculture with IL-4-treated and GYY4137-treated M0 macrophages. Collectively, our study demonstrated that hydrogen sulfide increased macrophages M2 polarization and subsequently promoted bone regeneration.