Hydrogen sulphide--a novel mediator of inflammation?

Monitoring variations in mitochondrial hydrogen sulfide using two-photon cyclometalated iridium(III) complex probe: A new strategy for ischemia-reperfusion drug discovery and efficacy evaluation

Hepatic ischemia-reperfusion injury (HIRI) is one of the main causes of liver insufficiency and failure after liver surgery. However, the effectiveness of current methods of treating HIRI is generally limited. Previous studies have shown that hydrogen sulfide (H2S) has a beneficial effect on HIRI, and an appropriate concentration of H2S can significantly reduce HIRI by protecting the mitochondria. Therefore, establishing an accurate imaging platform for monitoring variations in mitochondrial H2S is an effective strategy for anti-HIRI drug discovery and efficacy evaluation. To this end, a cyclometalated iridium(III) complex-based probe, Cym-Ir-EDB, was developed for detecting mitochondrial H2S in HIRI. Cym-Ir-EDB possesses good sensitivity, high selectivity, negligible cytotoxicity, and excellent mitochondrial-targeting ability, rendering it a promising imaging tool for analyzing variations in mitochondrial H2S in HIRI cells. Using Cym-Ir-EDB as a probe, anti-HIRI drugs were screened from isothiocyanates by monitoring variations in mitochondrial H2S in HIRI cells, for the first time. Moreover, the dynamics of mitochondrial H2S in HIRI cells were visualized and the response of HIRI to treatment with the screened erucin was monitored. The findings indicate that Cym-Ir-EDB can serve as a useful imaging platform for the precise imaging of mitochondrial H2S in HIRI, thereby contributing to anti-HIRI drug discovery and efficacy evaluation.

Gas Therapy: Generating, Delivery, and Biomedical Applications

Oxygen (O2), nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S), and hydrogen (H2) with direct effects, and carbon dioxide (CO2) with complementary effects on the condition of various diseases are known as therapeutic gases. The targeted delivery and in situ generation of these therapeutic gases with controllable release at the site of disease has attracted attention to avoid the risk of gas poisoning and improve their performance in treating various diseases such as cancer therapy, cardiovascular therapy, bone tissue engineering, and wound healing. Stimuli-responsive gas-generating sources and delivery systems based on biomaterials that enable on-demand and controllable release are promising approaches for precise gas therapy. This work highlights current advances in the design and development of new approaches and systems to generate and deliver therapeutic gases at the site of disease with on-demand release behavior. The performance of the delivered gases in various biomedical applications is then discussed.

Construction of a mitochondria-targeted near-infrared fluorescence turn-on fluorescent probe for H2S detection and imaging in living cells and drug-induced mice inflammatory models

The mechanism of the interaction between the signaling molecule hydrogen sulfide (H2S) and mitochondria and its related diseases is difficult to elusive. Thus it is urgent to develop effective methods and tools to visualize H2S in mitochondria and in vivo. In this work, a robust mitochondrial-targeting NIR fluorescence "turn-on" fluorescent probe, NIR1, was reported, by adopting a Changsha-OH near-infrared (NIR) dye as the NIR fluorophore, a 2,4-dinitrophenyl (DNB) moiety as both the responsive site of the H2S and the fluorescence quenching group of the NIR fluorophore, and an oxygen onium ion site as the mitochondria-targeting group, for the detection and analysis of H2S in living Raw 264.7 cells and drug-induced inflammatory mice models. NIR1 exhibited a much smaller background fluorescence signal in lack of H2S, whereas strong enhanced NIR fluorescence "turn-on" was detected in the presence of H2S, these results showed a low detection limit (30.2 nM) for quantitative detection of H2S in aqueous solutions with concentrations ranging from 0 to 1 μM H2S. These characteristics were beneficial to direct detection and imaging analysis of H2S in complicated biosystems. Therefore, first, NIR1 was applied for the NIR detection of mitochondrial H2S in living inflammatory cells with satisfactory results. Finally, NIR1 was applied to detect H2S in drug-induced inflammatory mice models with agreeable results, demonstrating that NIR1 as a molecular tool has an excellent practical application in the study of the interaction between inflammatory and H2S.

The Triple Crown: NO, CO, and H2S in cancer cell biology

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are three endogenously produced gases with important functions in the vasculature, immune defense, and inflammation. It is increasingly apparent that, far from working in isolation, these three exert many effects by modulating each other's activity. Each gas is produced by three enzymes, which have some tissue specificities and can also be non-enzymatically produced by redox reactions of various substrates. Both NO and CO share similar properties, such as activating soluble guanylate cyclase (sGC) to increase cyclic guanosine monophosphate (cGMP) levels. At the same time, H2S both inhibits phosphodiesterase 5A (PDE5A), an enzyme that metabolizes sGC and exerts redox regulation on sGC. The role of NO, CO, and H2S in the setting of cancer has been quite perplexing, as there is evidence for both tumor-promoting and pro-inflammatory effects and anti-tumor and anti-inflammatory activities. Each gasotransmitter has been found to have dual effects on different aspects of cancer biology, including cancer cell proliferation and apoptosis, invasion and metastasis, angiogenesis, and immunomodulation. These seemingly contradictory actions may relate to each gas having a dual effect dependent on its local flux. In this review, we discuss the major roles of NO, CO, and H2S in the context of cancer, with an effort to highlight the dual nature of each gas in different events occurring during cancer progression.

Intelligent polymeric hydrogen sulfide delivery systems for therapeutic applications

Hydrogen sulfide (H₂S) plays an important role in regulating various pathological processes such as protecting mammalian cell from harmful injuries, promoting tissue regeneration, and regulating the process of various diseases caused by physiological disorders. Studies have revealed that the physiological effects of H₂S are highly associated with its concentrations. At relatively low concentration, H₂S shows beneficial functions. However, long-time and high-dose donation of H₂S would inhibit regular biological process, resulting in cell dysfunction and apoptosis. To regulate the dosage of H₂S delivery for precision medicine, H₂S delivery systems with intelligent characteristics were developed and a variety of biocompatibility polymers have been utilized to establish intelligent polymeric H₂S delivery systems, with the abilities to specifically target the lesions, smartly respond to pathological microenvironments, as well as real-timely monitor H₂S delivery and lesion conditions by incorporating imaging-capable moieties. In this review, we focus on the design, preparation, and therapeutic applications of intelligent polymeric H₂S delivery systems in cardiovascular therapy, inflammatory therapy, tissue regenerative therapy, cancer therapy and bacteria-associated therapy. Strategies for precise H₂S therapies especially imaging-guided H₂S theranostics are highlighted. Since H₂S donors with stimuli-responsive characters are vital components for establishing intelligent H₂S delivery systems, the development of H₂S donors is also briefly introduced.

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H₂S is an endogenous gasotransmitter that plays important role in regulating various physiological and pathological pathways.

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Controlled H₂S delivery is vital since the therapeutic effects of H₂S are highly associated with its concentrations.

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Intelligent polymeric H₂S delivery systems possess specific targeting, stimuli responsive and imaging guided capabilities, representing a strategic option for next generation of therapies.

The potential impact of a probiotic: Akkermansia muciniphila in the regulation of blood pressure—the current facts and evidence

Akkermansia muciniphila (A. muciniphila) is present in the human gut microbiota from infancy and gradually increases in adulthood. The potential impact of the abundance of A. muciniphila has been studied in major cardiovascular diseases including elevated blood pressure or hypertension (HTN). HTN is a major factor in premature death worldwide, and approximately 1.28 billion adults aged 30–79 years have hypertension. A. muciniphila is being considered a next-generation probiotic and though numerous studies had highlighted the positive role of A. muciniphila in lowering/controlling the HTN, however, few studies had highlighted the negative impact of increased abundance of A. muciniphila in the management of HTN. Thus, in the review, we aimed to discuss the current facts, evidence, and controversy about the role of A. muciniphila in the pathophysiology of HTN and its potential effect on HTN management/regulation, which could be beneficial in identifying the drug target for the management of HTN.

Hypothermia-Triggered Mesoporous Silica Particles for Controlled Release of Hydrogen Sulfide to Reduce the I/R Injury of the Myocardium

Despite the fact that heart transplantation (HTx) is a relatively mature procedure, heart ischemic and reperfusion (I/R) injury during HTx remains a challenge. Even after a successful operation, the heart will be at risk of primary graft failure and mortality during the first year. In this study, temperature-sensitive polymer poly(N-n-propylacrylamide-co-N-tert-butyl acrylamide) (PNNTBA) was coated on diallyl trisulfide (DATS)-loaded mesoporous silica nanoparticles (DATS-MSN) to synthesize hypothermia-triggered hydrogen sulfide (H₂S) releasing particles (HT-MSN). Because the PNNTBA shell dissolves in phosphate-buffered saline at 4 °C, the loaded DATS could continuously release H₂S within 6 h when activated by glutathione (GSH). Furthermore, after co-culturing biocompatible HT-MSN with cardiomyocytes, H₂S released from HT-MSN at 4 °C was found to protect cardiomyocytes from ischemic and reperfusion (I/R) injury. In detail, the rate of cell apoptosis and lactate dehydrogenase activity was decreased, as manifested by increased BCL-2 expression and decreased BAX expression. More importantly, in an isolated heart preservation experiment, HT-MSN demonstrated potent protection against cardiac I/R injury and reduced expression of inflammatory factors TNF-α and IL-1β. This study provided a new method for the controlled release of H₂S by the donor and myocardial protection from I/R injury.

BODIPY-NBD dyad for highly selective and sensitive detection of hydrogen sulfide in cells and zebrafish

Hydrogen sulfide (H₂S) has been regarded as the third endogenous gas signaling molecule. The development of suitable tools for H₂S detection in vitro and in vivo has always been a focus of research. In this work, three BODIPY-NBD dyads (o/m/p-BNP) were designed and synthesized using BODIPY and NBD as the fluorophore and quencher, respectively. The position of the NBD moiety in the probe showed different fluorescence quenching abilities. All probes showed highly selective to H₂S. Probe o-BNP displayed the maximum fluorescence enhancement (c.a. 1300-fold) and the lowest detection limit (105 nM). Probe o-BNP can visualize the production of endogenous H₂S in HeLa cells and zebrafish.

Mechanism of preservation of the intestinal mucosa architecture and NF-κB/PGE2 reduction by hydrogen sulfide on cholera toxin-induced diarrhea in mice

AIMS

Investigate the involvement of Hydrogen sulfide (H₂S) in inflammatory parameters and intestinal morphology caused by cholera toxin (CT) in mice.

MAIN METHODS

Mice were subjected to the procedure of inducing diarrhea by CT in the isolated intestinal loop model. The intestinal loops were inoculated with H₂S donor molecules (NaHS and GYY 4137) or saline and CT. To study the role of EP2 and EP4 prostaglandin E2 (PGE2) receptors in the H₂S antisecretory effect, PAG (DL-propargylglycine - inhibitor of cystathionine-γ-lyase (CSE)), PF-04418948 (EP2 antagonist) and ONO-AE3-208 (EP4 antagonist) were used. The intestinal loops were evaluated for intestinal secretion, relation of the depth of villi and intestinal crypts, and real-time PCR for the mRNA of the CXCL2, IL-6, NOS-2, IL-17, NF-κB1, NF-κBIA, SLC6A4 and IFN-γ genes.

KEY FINDINGS

H₂S restored the villus/crypt depth ratio caused by CT. NaHS and GYY 4137 increased the expression of NF-κB1 and for the NF-κBIA gene, only GYY 4137 increased the expression of this gene. The increased expression of NF-κB inhibitors, NF-κB1 and NF-κBIA by H₂S indicates a possible decrease in NF-κB activity. The pretreatment with PAG reversed the protective effect of PF-04418948 and ONO-AE3-208, indicating that H₂S probably decreases PGE2 because in the presence of antagonists of this pathway, PAG promotes intestinal secretion.

SIGNIFICANCE

Our results point to a protective activity of H₂S against CT for promoting a protection of villus and crypt intestine morphology and also that its mechanism occurs at least in part due to decreasing the activity of NF-κB and PGE2.

Synthesis and Hydrogen Sulfide Releasing Properties of Diaminodisulfides and Dialkoxydisulfides

Heterosubstituted disulfides are an understudied class of molecules that have been used in biological studies, but they have not been investigated for their ability to release hydrogen sulfide (H₂S). The synthesis of two sets of chemicals with the diaminodisulfide (NSSN) and dialkoxydisulfide (OSSO) functional groups was reported. These chemicals were synthesized from commercially available sulfur monochloride or a simple disulfur transfer reagent. Both the diaminodisulfide and dialkoxydisulfide functional groups were found to have rapid rates of H₂S release in the presence of excess thiol. The release of H₂S was complete with 10 min, and the only byproducts were conversion of the thiols into disulfides and the amines or alcohols originally used in the synthesis of the diaminodisulfide or dialkoxydisulfide functional groups. These results will allow the design of H₂S releasing chemicals that also release natural, biocompatible alcohols or amines. Chemicals with the diaminodisulfide and dialkoxydisulfide functional groups may find applications in medicine where a controlled, burst release of H₂S is needed.

Biosynthesis, Quantification and Genetic Diseases of the Smallest Signaling Thiol Metabolite: Hydrogen Sulfide

Hydrogen sulfide (H2S) is a gasotransmitter and the smallest signaling thiol metabolite with important roles in human health. The turnover of H2S in humans is mainly governed by enzymes of sulfur amino acid metabolism and also by the microbiome. As is the case with other small signaling molecules, disease-promoting effects of H2S largely depend on its concentration and compartmentalization. Genetic defects that impair the biogenesis and catabolism of H2S have been described; however, a gap in knowledge remains concerning physiological steady-state concentrations of H2S and their direct clinical implications. The small size and considerable reactivity of H2S renders its quantification in biological samples an experimental challenge. A compilation of methods currently employed to quantify H2S in biological specimens is provided in this review. Substantial discrepancy exists in the concentrations of H2S determined by different techniques. Available methodologies permit end-point measurement of H2S concentration, yet no definitive protocol exists for the continuous, real-time measurement of H2S produced by its enzymatic sources. We present a summary of available animal models, monogenic diseases that impair H2S metabolism in humans including structure-function relationships of pathogenic mutations, and discuss possible approaches to overcome current limitations of study.

Current Perspective of Hydrogen Sulfide as a Novel Gaseous Modulator of Oxidative Stress in Glaucoma

Glaucoma is a group of diseases characterized by the progressive loss of retinal ganglion cells and their axons. Elevated intraocular pressure (IOP) is the main clinical manifestation of glaucoma. Despite being in the focus of the studies for decades, the characteristic and the exact pathology of neurodegeneration in glaucoma remains unclear. Oxidative stress is believed to be one of the main risk factors in neurodegeneration, especially its damage to the retinal ganglion cells. Hydrogen sulfide (H₂S), the recently recognized gas signaling molecule, plays a pivotal role in the nervous system, vascular system, and immune system. It has also shown properties in regulating oxidative stress through different pathways in vivo. In this review, we summarize the distribution and the properties of H₂S within the eye with an emphasis on its role in modulating oxidative stress in glaucoma.

A fluorescent probe for specific detection of cysteine in lysosomes via dual-color mode imaging

Biothiols, as part of the reactive sulfur species (RSS), are a class of bioactive molecules that play important physiological roles in human body. However, due to the similarity in structure and reaction sites of biothiols, it is difficult to differentiated detection them at the same time. In this work, a fluorescent probe CM-NBD combined coumarin derivative and 7-nitrobenzofurazan has been developed, which can effectively detect biothiols through simple ether cleavage. Because of a specific location group, CM-NBD can well localize in lysosomes with a high co-localization coefficient. Interesting, due to the weakly acidic environment of lysosomes, Cys can be distinguished from Hcy/GSH and H₂S via dual-color mode. The probe is able not only to image exogenous biothiols but also to discriminate Cys from Hcy/GSH and H₂S in cells and zebrafish model.

Synthesis and application of a new chemosensor based on the thiazolylazo-quinazolinone hybrid for detection of F- and S2- in aqueous solutions

A new chemosensor based on the thiazolylazo-quinazolinone hybrid (TAQH) was designed and synthesized for naked-eye sensitive detection of F^- and S^2-in aqueous acetonitrile solution. Spectral characterization of TAQH using FT-IR, ¹H NMR, and ¹³C NMR analysis revealed that the probe TAQH was successfully synthesized using a two steps reaction, including the diazotization-coupling and condensation reactions, respectively. The ion sensing ability of TAQH toward a wide range of anions and metal ions was evaluated by naked-eye detection method and UV-Vis absorption spectroscopy. The chemosensor TAQH displayed a fast and clear color change from yellow to red in the presence of F^- and S^2- ions, enabling easily detect with the naked eye. This clear color change is due to the effective interaction of the basic F^- and S^2- anions with hydroxyl group of chemosensor as a binding site. The experimental data also revealed that the F^- and S^2- ions were sensed by the probe TAQH over a wide pH range from 3 to 8. The results also confirmed that the TAQH has a wide linear detection range for F^- and S^2- ions. From UV-vis titration experiment, the limit of detection (LOD) for F^- and S^2- ions was found to be 3.1 μM and 5.7 μM, respectively. For quantitative measurements, the paper test strips containing TAQH were successfully fabricated and applied to detect F^- and S^2- ions in aqueous solutions. Furthermore, Job's plot based on spectroscopic data showed one-to-one stoichiometry for the interaction of anions with probe TAQH. Therefore, the proposed chemosensor with excellent features like the cost-effective, high sensitively and selectively and short response times can be utilized in any physical and biological conditions.

CBS-Induced H2S Generation in Hippocampus Inhibits EA-Induced Analgesia

Hydrogen sulfide (H₂S) is an important mediator participating in both physiological and pathological systems and related to the inflammatory process. Acupuncture has a therapeutic effect on inflammatory pain. However, whether H₂S generated in the central nervous system (CNS) is a mediator of electroacupuncture (EA) treatment for inflammatory pain is unknown. We injected complete Freund's adjuvant (CFA) to induce inflammatory pain and applied EA treatment as an interventional strategy for pain relief. The results presented here show that S-adenosyl-l-methionine (SAM), an allosteric activator of cystathionine-β-synthetase (CBS), may reverse the therapeutic effect of EA. CBS-induced H₂S generation might get involved in the mechanism of EA-induced analgesia in the hippocampus on chronic inflammatory pain.

Multifluorinated Aryl Azides for the Development of Improved H2 S Probes, and Fast Strain-promoted Azide-Alkyne Cycloaddition and Staudinger Reactions

The development of advanced bioorthogonal reactions for detection and labeling of biomolecules is significant in chemical biology. Recently, researchers have found that multifluorinated aryl azides hold great potential for the development of improved bioorthogonal reactions. The fluorine atom can be a perfect substituent group because of its properties of excellent electronegativity and small steric hindrance. In this Minireview, we discuss recent developments of improved hydrogen sulfide (H₂ S) fluorescence probes, fast strain-promoted azide-alkyne cycloaddition (SPAAC) and nonhydrolysis Staudinger reactions based on the use of multifluorinated aryl azides. Additionally, kinetic studies and biological applications of these reactions are also presented.

A novel imidazole derived colorimetric and fluorometric chemosensor for bifunctional detection of copper (II) and sulphide ions in environmental water samples

Herein, a novel "ON-OFF" colorimetric and fluorometric chemosensor; 1N-allyl-2-(2, 5-dimethoxyphenyl)-4, 5-diphenyl-1H-imidazole (ADPPI), was constructed for sequential determination of Cu²⁺ and S^2- ions in aqueous media. The interaction between chemosensor ADPPI and different metal cations was investigated using UV-VIS and fluorimetric spectroscopy. ADPPI showed a favorable and good interaction with Cu²⁺ ions producing blue colored solution peaked at 610 nm with blue fluorescence at λ_em. = 447 nm. The produced complex between Cu²⁺ ions and ADPPI can be used as a cascade probe for detection of S^2- ions. The detection limits (LODs) were 1.01 nM and 1.25 μM for Cu²⁺ and S^2- ions, respectively (the lowest between the family of colorimetric and fluorometric chemosensors). To further increase the applicability of the proposed method, Cu²⁺ and S^2- ions concentrations were measured in environmental water samples.

Assessment of the effect of sodium hydrogen sulfide (hydrogen sulfide donor) on cisplatin-induced testicular toxicity in rats

Cisplatin (CIS) is an antineoplastic drug able to produce free radicals that are capable to induce various side effects in different tissues. Hydrogen sulfide (H₂S) has notable antioxidant, anti-apoptotic, and anti-inflammatory effects in different systems but its role in male reproductive system is not fully understood. In the present research, the effect of sodium hydrosulfide (NaHS) on cisplatin-induced testicular toxicity in male rats was studied. Thirty-two Sprague-Dawley rats were equally divided into 4 groups. The control group was treated with normal saline by intraperitoneal injection. The NaHS group received NaHS (200 μg/kg/day) intraperitoneally for 15 days. The CIS group received single dose of cisplatin (5 mg/kg) intraperitoneally, while the combination of CIS and NaHS was given to the CIS+ NaHS group. At the end of the study, body and testicular weights, plasma testosterone level, histological and morphometrical alterations, inflammation via IL-1β protein, lipid peroxidation, and activity of antioxidant enzymes (including glutathione peroxidase, superoxide dismutase, and catalase) of testicular tissue were evaluated. CIS injection revealed a significant decrease (p < 0.01) in body and testis weights, plasma testosterone concentration, diameter of seminiferous tubules, germinal epithelium thickness, the number of Sertoli cells, spermatogonia and spermatocyte, Johnsen's testicular score, and testicular antioxidant enzymes, whereas it caused a significant increase (p < 0.01) in lumen diameter of the seminiferous tubules, level of lipid peroxidation, and IL-1β protein expression when compared with the control group. NaHS administration to CIS-treated rats provided marked improvement (p < 0.05) in all biochemical, histological, and morphometrical changes induced by CIS. The beneficial effects of NaHS were mediated, at least partly, by its antioxidant and anti-inflammatory properties.

Synthesis and application of coumarin fluorescence probes

In recent years, the research on fluorescent probes has developed rapidly. Coumarin fluorescent probes have also been one of the hot topics in recent years. For the synthesis and application of coumarin fluorescent probes, great progress has been made. Coumarin fluorescent probes have become more and more widely used in biochemistry, environmental protection, and disease prevention, and have broad prospects. This review introduces the three main light emitting mechanisms (PET, ICT, FRET) of fluorescent probes, and enumerates some probes based on this light emitting mechanism. In terms of the synthesis of coumarin fluorescent probes, the existing substituents on the core of coumarin compounds were modified. Based on the positions of the modified substituents, some of the fluorescent probes reported in the past ten years are listed. Most of the fluorescent probes are formed by modifying the 3 and 7 position substituents on the mother nucleus, and the 4 and 8 position substituents are relatively less modified. In terms of probe applications, the detection and application of coumarin fluorescent probes for Cu²⁺, Hg²⁺, Mg²⁺, Zn²⁺, pH, environmental polarity, and active oxygen and sulfide in the past ten years are mainly introduced.

In recent years, the research on fluorescent probes has developed rapidly.

Mammalian Transient Receptor Potential TRPA1 Channels: From Structure to Disease

The transient receptor potential ankyrin (TRPA) channels are Ca²⁺-permeable nonselective cation channels remarkably conserved through the animal kingdom. Mammals have only one member, TRPA1, which is widely expressed in sensory neurons and in non-neuronal cells (such as epithelial cells and hair cells). TRPA1 owes its name to the presence of 14 ankyrin repeats located in the NH₂ terminus of the channel, an unusual structural feature that may be relevant to its interactions with intracellular components. TRPA1 is primarily involved in the detection of an extremely wide variety of exogenous stimuli that may produce cellular damage. This includes a plethora of electrophilic compounds that interact with nucleophilic amino acid residues in the channel and many other chemically unrelated compounds whose only common feature seems to be their ability to partition in the plasma membrane. TRPA1 has been reported to be activated by cold, heat, and mechanical stimuli, and its function is modulated by multiple factors, including Ca²⁺, trace metals, pH, and reactive oxygen, nitrogen, and carbonyl species. TRPA1 is involved in acute and chronic pain as well as inflammation, plays key roles in the pathophysiology of nearly all organ systems, and is an attractive target for the treatment of related diseases. Here we review the current knowledge about the mammalian TRPA1 channel, linking its unique structure, widely tuned sensory properties, and complex regulation to its roles in multiple pathophysiological conditions.

Roles of Small-Molecule Compounds in Plant Adventitious Root Development

Adventitious root (AR) is a kind of later root, which derives from stems and leaf petioles of plants. Many different kinds of small signaling molecules can transmit information between cells of multicellular organisms. It has been found that small molecules can be involved in many growth and development processes of plants, including stomatal movement, flowering, fruit ripening and developing, and AR formation. Therefore, this review focuses on discussing the functions and mechanisms of small signaling molecules in the adventitious rooting process. These compounds, such as nitric oxide (NO), hydrogen gas (H2), hydrogen sulfide (H2S), carbon monoxide (CO), methane (CH4), ethylene (ETH), and hydrogen peroxide (H2O2), can be involved in the induction of AR formation or development. This review also sums the crosstalk between these compounds. Besides, those signaling molecules can regulate the expressions of some genes during AR development, including cell division genes, auxin-related genes, and adventitious rooting-related genes. We conclude that these small-molecule compounds enhance adventitious rooting by regulating antioxidant, water balance, and photosynthetic systems as well as affecting transportation and distribution of auxin, and these compounds further conduct positive effects on horticultural plants under environmental stresses. Hence, the effect of these molecules in plant AR formation and development is definitely a hot issue to explore in the horticultural study now and in the future.

Measurement of Protein Persulfidation: Improved Tag-Switch Method

Hydrogen sulfide (H₂S) is an endogenously produced signaling gasotransmitter, generated by the enzymes cystathionine γ-lyase, cystathionine β-synthase, and 3-mercaptopyruvate sulfurtransferase. The involvement of H₂S in numerous physiological, as well as pathophysiological conditions, was established over the past decade. However, the exact mechanism(s) of regulation of the biological functions by H₂S are under active investigations. It is proposed that the oxidative posttranslational modification of protein cysteine residues, known as persulfidation, could be the main mechanism of action of H₂S. Protein persulfides show similar reactivity to thiols, which represents one of the main obstacles in the development of a reliable method for detection of this specific protein modification. Subsequently, having a selective method for persulfide detection is of utmost importance in order to fully understand the physiological and pathophysiological role of H₂S. Several methods have been proposed for the detection of protein persulfidation, all of which are highlighted in this chapter. Furthermore, we provide a detailed description and protocol for the first selective persulfide labeling method, a tag-switch method, developed in our group.

Lysosome-targeted two-photon fluorescent probes for rapid detection of H2S in live cells

Two novel two-photon fluorescent probes (BHNP-DA and M2) were designed and synthesized and show good selectivity and high sensitivity to H₂S.

Oxidative stress in autoimmune rheumatic diseases

The management of patients with autoimmune rheumatic diseases such as rheumatoid arthritis (RA) remains a significant challenge. Often the rheumatologist is restricted to treating and relieving the symptoms and consequences and not the underlying cause of the disease. Oxidative stress occurs in many autoimmune diseases, along with the excess production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The sources of such reactive species include NADPH oxidases (NOXs), the mitochondrial electron transport chain, nitric oxide synthases, nitrite reductases, and the hydrogen sulfide producing enzymes cystathionine-β synthase and cystathionine-γ lyase. Superoxide undergoes a dismutation reaction to generate hydrogen peroxide which, in the presence of transition metal ions (e.g. ferrous ions), forms the hydroxyl radical. The enzyme myeloperoxidase, present in inflammatory cells, produces hypochlorous acid, and in healthy individuals ROS and RNS production by phagocytic cells is important in microbial killing. Both low molecular weight antioxidant molecules and antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and peroxiredoxin remove ROS. However, when ROS production exceeds the antioxidant protection, oxidative stress occurs. Oxidative post-translational modifications of proteins then occur. Sometimes protein modifications may give rise to neoepitopes that are recognized by the immune system as 'non-self' and result in the formation of autoantibodies. The detection of autoantibodies against specific antigens, might improve both early diagnosis and monitoring of disease activity. Promising diagnostic autoantibodies include anti-carbamylated proteins and anti-oxidized type II collagen antibodies. Some of the most promising future strategies for redox-based therapeutic compounds are the activation of endogenous cellular antioxidant systems (e.g. Nrf2-dependent pathways), inhibition of disease-relevant sources of ROS/RNS (e.g. isoform-specific NOX inhibitors), or perhaps specifically scavenging disease-related ROS/RNS via site-specific antioxidants.

Protective effect of methylsulfonylmethane in caerulein-induced acute pancreatitis and associated lung injury in mice

Objectives

In the present study, we have elaborated the anti-inflammatory mechanism of MSM through homing of CD34+ stem cells towards an inflamed region by regulating hydrogen sulfide (H2S) in an in vivo model of caerulein-induced acute pancreatitis (AP) and associated lung injury.

Methods

Male Swiss mice were treated with hourly intraperitoneal injections of caerulein (50 μg/kg) for 6 h. MSM (500 mg/kg) was administered intraperitoneally 1 h after the first caerulein injection (therapeutic). The serum amylase activity and myeloperoxidase (MPO) activity in lung and pancreas were measured. The levels of H2S and interleukin (IL)-1β, cystathionine-γ-lyase (CSE) and CD34+ expressions in pancreas and lungs were determined by RT-PCR and ELISA.

Key Findings

Methylsulfonylmethane significantly ameliorated pancreas and lung histopathological changes, decreased serum amylase, MPO activity and inhibited caerulein-induced IL-1β expression. Furthermore, MSM reduced caerulein-induced H2S levels by alleviating the expression of CSE in pancreas and lungs and increased CD34 expression and inhibited nuclear factor (NF)-κB translocation in caerulein-induced AP and associated lung injury.

Conclusions

These findings indicate that MSM can effectively reduce inflammatory responses and induce the homing of CD34+ cells to the injured tissues.

The dichotomous role of H2S in cancer cell biology? Déjà vu all over again

Nitric oxide (NO) a gaseous free radical is one of the ten smallest molecules found in nature, while hydrogen sulfide (H2S) is a gas that bears the pungent smell of rotten eggs. Both are toxic yet they are gasotransmitters of physiological relevance. There appears to be an uncanny resemblance between the general actions of these two gasotransmitters in health and disease. The role of NO and H2S in cancer has been quite perplexing, as both tumor promotion and inflammatory activities as well as anti-tumor and antiinflammatory properties have been described. These paradoxes have been explained for both gasotransmitters in terms of each having a dual or biphasic effect that is dependent on the local flux of each gas. In this review/commentary, I have discussed the major roles of NO and H2S in carcinogenesis, evaluating their dual nature, focusing on the enzymes that contribute to this paradox and evaluate the pros and cons of inhibiting or inducing each of these enzymes.

IL-1β augments H2S-induced increase in intracellular Ca2+ through polysulfides generated from H2S/NO interaction

H₂S has excitatory and inhibitory effects on Ca²⁺ signals via transient receptor potential ankyrin 1 (TRPA1) and ATP-sensitive K⁺ channels, respectively. H₂S converts intracellularly to polysulfides, which are more potent agonists for TRPA1 than H₂S. Under inflammatory conditions, changes in the expression and activity of these H₂S target channels and/or the conversion of H₂S to polysulfides may modulate H₂S effects. Effects of proinflammatory cytokines on H₂S-induced Ca²⁺ signals and polysulfide production in RIN14B cells were examined using fluorescence imaging with fura-2 and SSP4, respectively. Na₂S, a H₂S donor, induced 1) the inhibition of spontaneous Ca²⁺ signals, 2) inhibition followed by [Ca²⁺]_i increase, and 3) rapid [Ca²⁺]_i increase without inhibition in 50% (23/46), 22% (10/46), and 17% (8/46) of cells tested, respectively. IL-1β augmented H₂S-induced [Ca²⁺]_i increases, which were inhibited by TRPA1 and voltage-dependent L-type Ca²⁺ channel blockers. However, IL-1β treatment did not affect [Ca²⁺]_i increases evoked by a TRPA1 agonist or high concentration of KCl. Na₂S increased intracellular polysulfide levels, which were enhanced by IL-1β treatment. A NOS inhibitor suppressed the increased polysulfide production and [Ca²⁺]_i increase in IL-1β-treated cells. These results suggest that IL-1β augments H₂S-induced [Ca²⁺]_i increases via the conversion of H₂S to polysulfides through NO synthesis, but not via changes in the activity and expression of target channels. Polysulfides may play an important role in the effects of H₂S during inflammation.

The protective effects of GYY4137 on ipsilateral testicular injury in experimentally varicocele-induced rats

The aim of the present study was to evaluate whether morpholin-4-ium 4 methoxyphenyl (morpholino) phosphonodithioate (GYY4137) exhibits a protective effect on ipsilateral testicular injury in experimentally varicocele (VC)-induced rats. A total of 48 rats were randomly divided into the following 6 groups (n=8 each): Group A (control group); group B (sham group); group C (VC group); group D (VC group administered 5 mg/kg/day GYY4137); group E (VC group administered 10 mg/kg/day GYY4137) and group F (VC group administered 20 mg/kg/day GYY4137). Indicators of oxidative stress, apoptosis and inflammation were measured to evaluate the effect of GYY4137 on ipsilateral testicular injury. Compared with groups A and B, rats in group C exhibited severe histological changes and an increase in oxidative stress, apoptosis and inflammation. By contrast, amelioration of testicular damage was evident in the group D, E and F that were treated with GYY4137. These results demonstrate that GYY4137 may be a promising therapy to treat VC as it alleviates oxidative stress, apoptosis and inflammation in experimentally VC-induced rats.

AMPK Serves as a Therapeutic Target Against Anemia of Inflammation

AIMS

Anemia of inflammation (AI), the second prevalent anemia, is associated with worse prognosis and increased mortality in numerous chronic diseases. We recently reported that the gasotransmitter hydrogen sulfide (H₂S) suppressed the inflammatory activation of signal transducer and activator of transcription 3 (STAT3) and hepcidin, the critical mediators of AI. Adenosine 5'-monophosphate-activated protein kinase (AMPK) is a novel inflammatory regulator and might be activated by H₂S. In this study, we determined whether AMPK played a role in H₂S-mediated anti-inflammatory response in AI and evaluated the therapeutic potential of AMPK against AI by pharmacological and clinical approaches.

RESULTS

We showed that AMPK mediated the inhibition of STAT3, hepcidin, and AI by H₂S during inflammation. Moreover, pharmacological and genetic activation of AMPK ameliorated hepcidin production, corrected iron dysregulation, and relieved hypoferremia and anemia in both acute and chronic inflammation models in mice. Mechanistic studies indicated that AMPK suppressed STAT3/hepcidin activation by promoting proteasome-mediated Janus kinase 2 (JAK2) degradation, which was dependent on the intact function of suppressor of cytokine signaling 1 (SOCS1) and increased interactions between SOCS1 and JAK2. Most importantly, the AMPK activator metformin was associated with decreased serum hepcidin content and anemia morbidity in Chinese type 2 diabetes mellitus patients.

INNOVATION

This is the first study to demonstrate the inhibition of inflammatory hepcidin and AI by AMPK-induced JAK2 degradation. Our work uncovered AMPK as a novel therapeutic target, and metformin as a potential therapy against AI.

CONCLUSION

The present work demonstrated that AMPK mediated the therapeutic effects of H₂S and relieved AI by promoting SOCS1-mediated JAK2 degradation. Antioxid. Redox Signal. 27, 251-268.

Hydrogen sulfide therapy in brain diseases: from bench to bedside

Hydrogen sulfide (H₂S) has been recognized and studied for nearly 300 years, but past researches mainly focus on its toxicity effect. During the past two decades, the majority of researches have reported that H₂S is a novel endogenous gaseous signal molecule in organisms, and play an important role in various systems and diseases. H₂S is mainly produced by three enzymes, including cystathionine β-synthase, cystathionine γ-lyase and 3-mercaptopyruvate sulfurtransferase along with cysteine aminotransferase. H₂S had been firstly reported as a neuromodulator in the brain, because of its essential role in the facilitating hippocampal long-term potentiation at physiological concentration. It is subsequently reported that H₂S may have relevance to neurologic disorders through antioxidative, anti-inflammatory, anti-apoptotic and additional effects. Recent basic medical studies and preclinical studies on neurologic diseases have demonstrated that the administration of H₂S at physiological or pharmacological levels attenuates brain injury. However, the neuroprotective effect of H₂S is concentration-dependent, only a comparatively low dose of H₂S can provide beneficial effect. Herein, we review the neuroprotevtive role of H₂S therapy in brain diseases from its mechanism to clinical application in animal and human subjects, and therefore provide the potential strategies for further clinical treatment.

Pro-inflammatory cytokine-driven PI3K/Akt/Sp1 signalling and H2S production facilitates the pathogenesis of severe acute pancreatitis

Severe acute pancreatitis (SAP) is a disease usually associated with systemic organ dysfunction or pancreatic necrosis. Most patients with SAP suffer from defective intestinal motility in the early phase of the disease. Additionally, SAP-induced inflammation produces hydrogen sulphide (H₂S) that impairs the gastrointestinal (GI) system. However, the exact mechanism of H₂S in the regulation of SAP is yet to be elucidated. In the present paper, we used a rat model of SAP to evaluate the role of H₂S on intestinal motility by counting the number of bowel movements and investigating the effect of H₂S on inflammation. We treated colonic muscle cells (CMCs) with SAP plasma, tumour necrosis factor-α (TNF-α) or interleukin-6 (IL-6) and measured the expressions of H₂S-producing enzymes cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS) and Sp1 and PI3K/Akt by using quantitative PCR, Western blotting and immunohistochemical detection. We used the PI3K inhibitor LY294002 and the siRNA si-Sp1 to suppress the activity of the PI3K/Akt/Sp1 signalling pathway. We found that, in the SAP rat model, H₂S facilitated an inhibitory effect on intestinal motility and enhanced the inflammatory response caused by SAP (P<0.05). The expressions of CSE and CBS in CMCs were significantly increased after treatment with TNF-α or IL-6 (P<0.05). Blocking the PI3K/Akt/Sp1 pathway remarkably inhibited the synthesis of CSE and CBS. Our data demonstrated that H₂S plays a vital role in the pathogenesis of SAP and that SAP is modulated by inflammation driven by the PI3K/Akt/Sp1 signalling pathway.

New method for quantification of gasotransmitter hydrogen sulfide in biological matrices by LC-MS/MS

Hydrogen sulfide exists widely in mammalian tissues and plays a vital role in physiological and pathophysiological processes. However, striking differences with orders of magnitude were observed for the detected hydrogen sulfide concentrations in biological matrices among different measurements in literature, which lead to the uncertainty for examination the biological relevance of hydrogen sulfide. Here, we developed and validated a liquid chromatography- mass spectrometry (LC-MS/MS) method for the determination of hydrogen sulfide in various biological matrices by determination of a derivative of hydrogen sulfide and monobromobimane named sulfide dibimane (SDB). ³⁶S-labeled SDB was synthesized and validated for using as an internal standard. This method has been successfully used to measure hydrogen sulfide levels in a broad range of biological matrices, such as blood, plasma, tissues, cells, and enzymes, across different species. Moreover, a novel mode that hydrogen sulfide could loosely and non-covalently bind to human serum protein (HSA) and hemoglobin (HB) was revealed by using the developed method.

Exogenous hydrogen sulfide protects against high glucose‑induced inflammation and cytotoxicity in H9c2 cardiac cells

Hyperglycemia serves an important role in the pathogenesis of diabetic cardiomyopathy. The aim of the present study was to investigate whether exogenous hydrogen sulfide (H2S) protects against high glucose‑induced inflammation and cytotoxicity in cardiac cells by inhibiting the p38 mitogen‑activated protein kinase (MAPK)/nuclear factor‑κB (NF‑κB), cyclooxygenase‑2 (COX‑2) and inducible nitric oxide synthase (iNOS) signaling pathways. Rat H9c2 myocardium cells were exposed to 33 mM glucose (high glucose, HG) for 24 h to stimulate HG‑induced cytotoxicity. One group of cells was pretreated with NaHS (a donor of H2S) prior to HG exposure, and cell viability was determined using the Cell Counting Kit‑8 assay. The protein expression levels of p38MAPK, the phosphorylated p65 subunit of NF‑κB, iNOS, COX‑2 and caspase‑3 were analyzed by western blotting, and the protein expression levels of interleukin (IL)‑1β and IL‑6 were detected by enzyme‑linked immunosorbent assay (ELISA). Pretreatment of H9c2 cells with NaHS for 30 min prior to exposure to HG significantly ameliorated the expression of p38MAPK and NF‑κB. In addition, pretreatment with NaHS markedly attenuated p38MAPK/NF‑κB‑mediated cytotoxicity and inflammation, as evidenced by the significant increase in cell viability and decrease in iNOS, COX‑2, IL‑1β and IL‑6 expression levels. Furthermore, treatment of cells with NaHS significantly decreased the expression of caspase‑3, which suggested that NaHS attenuated HG‑induced apoptosis. In conclusion, the results of the present study provided evidence to suggest that exogenous H2S protects against HG‑induced cytotoxicity and inflammation in H9c2 cardiac cells. H2S may exert these cytoprotective effects via inhibition of the p38MAPK/NF‑κB, COX‑2 and iNOS signaling pathways.

Hydrogen Sulfide-Mediated Polyamines and Sugar Changes Are Involved in Hydrogen Sulfide-Induced Drought Tolerance in Spinacia oleracea Seedlings

Hydrogen sulfide (H2S) is a newly appreciated participant in physiological and biochemical regulation in plants. However, whether H2S is involved in the regulation of plant responses to drought stress remains unclear. Here, the role of H2S in the regulation of drought stress response in Spinacia oleracea seedlings is reported. First, drought stress dramatically decreased the relative water content (RWC) of leaves, photosynthesis, and the efficiency of PSII. Moreover, drought caused the accumulation of ROS and increased the MDA content. However, the application of NaHS counteracted the drought-induced changes in these parameters. Second, NaHS application increased the water and osmotic potential of leaves. Additionally, osmoprotectants such as proline and glycinebetaine (GB) content were altered by NaHS application under drought conditions, suggesting that osmoprotectant contributes to H2S-induced drought resistance. Third, the levels of soluble sugars and polyamines (PAs) were increased differentially by NaHS application in S. oleracea seedlings. Moreover, several genes related to PA and soluble sugar biosynthesis, as well as betaine aldehyde dehydrogenase (SoBADH), choline monooxygenase (SoCMO), and aquaporin (SoPIP1;2), were up-regulated by H2S under drought stress. These results suggest that H2S contributes to drought tolerance in S. oleracea through its effect on the biosynthesis of PAs and soluble sugars. Additionally, GB and trehalose also play key roles in enhancing S. oleracea drought resistance.

Fast-Response Turn-on Fluorescent Probes Based on Thiolysis of NBD Amine for H2 S Bioimaging

Hydrogen sulfide (H2 S) is an important endogenous signaling molecule with multiple biological functions. New selective fluorescent turn-on probes based on fast thiolyling of NBD (7-nitro-1,2,3-benzoxadiazole) amine were explored for sensing H2 S in aqueous buffer and in living cells. The syntheses of both probes are simple and quite straightforward. The probes are highly sensitive and selective toward H2 S over other biologically relevant species. The fluorescein-NBD-based probe showed 65-fold green fluorescent increase upon H2 S activation. The rhodamine-NBD-based probe reacted rapidly with H2 S (t1/2 ≈1 min) to give a 4.5-fold increase in red fluorescence. Moreover, both probes were successfully used for monitoring H2 S in living cells and in mice. Based on such probe-based tools, we could observe H2 O2 -induced H2 S biogenesis in a concentration-dependent and time-dependent fashion in living cells.

Cross talk between polysulfide and nitric oxide in rat peritoneal mast cells

The aim of this study was to define the effects of polysulfide on intracellular Ca(2+) concentration ([Ca(2+)]i) and the underlying machinery, especially from the hydrogen sulfide (H2S) and nitric oxide (NO) perspectives, in rat peritoneal mast cells. We found that a polysulfide donor, Na2S4, increased [Ca(2+)]i, which is both extracellular and intracellular Ca(2+) dependent. Intracellular Ca(2+) release induced by Na2S4 was attenuated by the addition of a ryanodine receptor blocker. A slow-releasing H2S donor, GYY4137, dose dependently increased [Ca(2+)]i that was independent from extracellular Ca(2+) influx. The GYY4137-induced [Ca(2+)]i release was partially attenuated in the presence of the ryanodine receptor blocker. Both polysulfide and H2S donors increased the intracellular NO levels in DAF-2-loaded mast cells, which were abolished by an NO scavenger, cPTIO. Inhibition of NO synthase (NOS) significantly abolished the polysulfide- or H2S-donor-induced [Ca(2+)]i elevation in the absence of extracellular Ca(2+) An NO donor, diethylamine (DEA) NONOate, increased [Ca(2+)]i in a concentration-dependent manner, in which both extracellular and intracellular Ca(2+) are associated. At higher concentrations, the DEA NONOate-induced [Ca(2+)]i increases were attenuated in the absence of extracellular Ca(2+) and by the addition of the ryanodine receptor blocker. H2S and NO dose dependently induced polysulfide production. Curiously, polysulfide, H2S, and NO donors had no effect on mast cell degranulation. Among synthases, cystathionine-γ-lyase, and neuronal NOS seemed to be the major H2S- and NO-producing synthases, respectively. These results indicate that polysulfide acts as a potential signaling molecule that regulates [Ca(2+)]i homeostasis in rat peritoneal mast cells via a cross talk with NO and H2S.

Korean red ginseng ameliorated experimental pancreatitis through the inhibition of hydrogen sulfide in mice

AIM

Effective therapy to treat acute pancreatitis (AP) or to prevent its recurrence/complication is still not available. Based on previous results that suggest that: i) hydrogen sulfide (H2S) levels were significantly increased in pancreatitis and gastritis and ii) Korean red ginseng (KRG) efficiently attenuated Helicobacter pylori-associated gastritis through the suppressive actions of H2S, we hypothesized that KRG can ameliorate experimental pancreatitis through suppression of H2S generation.

METHODS

C57BL/6 mice were pre-administered KRG and then subjected to cerulein injection or pancreatic duct ligation (PDL) to induce pancreatitis. Blood and pancreas tissues were collected and processed to measure serum levels of amylase, lipase and myeloperoxidase and the concentration of H2S and the levels of various inflammatory cytokine in pancreatic tissues of mice with induced AP.

RESULTS

KRG significantly inhibited NaHS-induced COX-2 and TNF-α mRNA in pancreatic cells, but dl-propargylglycine did not. KRG ameliorated cerulein-induced edematous pancreatitis accompanied with significant inactivation of NF-κB and JNK in pancreatic tissues of C57BL/6 mice (p < 0.001) and also significantly ameliorated PDL-induced necrotizing pancreatitis (p<0.01); in both conditions, the significant suppression of H2S resulting from KRG pretreatment afforded rescuing outcomes. Along with suppressed levels of H2S consequent to depressed expressions of CBS and CSE mRNA, KRG administration efficiently decreased the serum level of amylase, lipase, and myeloperoxidase and the expression of inflammatory cytokines in animal models of mild or severe AP.

CONCLUSIONS

These results provide evidence for the preventive and therapeutic roles of KRG against AP mediated by H2S suppression.

Gastrointestinal safety, chemotherapeutic potential, and classic pharmacological profile of NOSH-naproxen (AVT-219) a dual NO- and H2S-releasing hybrid

Naproxen (NAP) is a potent nonsteroidal anti-inflammatory drug (NSAID) with a favorable cardiovascular profile. However, its long-term use may lead to serious gastrointestinal and renal side effects. NOSH- (nitric oxide and hydrogen sulfide) releasing naproxen (NOSH-NAP, AVT-219) belongs to a new class of anti-inflammatory agents designed to overcome these limitations. We compared the gastrointestinal safety, anti-inflammatory, analgesic, antipyretic, and antiplatelet properties of AVT-219 to that of NAP in preclinical animal models. We also evaluated its anticancer effects in 11 human cancer cell (HCC) lines of six different tissue origins and in a chemotherapeutic xenograft mouse model of colon cancer. AVT-219: (1) was orders of magnitude more potent than NAP in inhibiting the growth of cultured HCC; (2) was safe to the stomach, whereas NAP caused significant ulceration; (3) showed strong anti-inflammatory, analgesic, antipyretic, and antiplatelet properties comparable to NAP; and (4) NAP caused a significant rise in plasma tumor necrosis factor-alpha (TNFα), whereas in the AVT-219-treated rats this rise was significantly less. Mechanistically, AVT-219 was a strong antioxidant, inhibited cyclooxygenase (COX)-1 and -2, thus reducing prostaglandin (PG) E2. In xenografts, AVT-219 significantly reduced tumor growth and tumor mass with no sign of GI toxicity, whereas NAP-treated mice died due to GI bleeding. AVT-219 displayed considerable safety and potency in inhibiting HCC growth; was an effective analgesic, antipyretic, antiplatelet, and anti-inflammatory; and was significantly more efficacious than NAP in reducing the growth of established tumors in a xenograft mouse model.

H2S protects against fatal myelosuppression by promoting the generation of megakaryocytes/platelets

Background

Our previous pilot studies aimed to examine the role of hydrogen sulfide (H₂S) in the generation of endothelial progenitor cells led to an unexpected result, i.e., H₂S promoted the differentiation of certain hematopoietic stem/progenitor cells in the bone marrow. This gave rise to an idea that H₂S might promote hematopoiesis.

Methods

To test this idea, a mice model of myelosuppression and cultured fetal liver cells were used to examine the role of H₂S in hematopoiesis.

Results

H₂S promoted the generation of megakaryocytes, increased platelet levels, ameliorate entorrhagia, and improved survival. These H₂S effects were blocked in both in vivo and in vitro models with thrombopoietin (TPO) receptor knockout mice (c-mpl^−/− mice). In contrast, H₂S promoted megakaryocytes/platelets generation in both in vivo and in vitro models with TPO knockout mice (TPO^−/− mice).

Conclusions

H₂S is a novel promoter for megakaryopoiesis by acting on the TPO receptors but not TPO to generate megakaryocytes/platelets.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0244-7) contains supplementary material, which is available to authorized users.