Effects of hydrogen sulfide on mitochondrial function and cellular bioenergetics

Novel role of FTO in regulation of gut-brain communication via Desulfovibrio fairfieldensis-produced hydrogen sulfide under arsenic exposure

Fat mass and obesity-associated protein (FTO) is the key demethylase that reverses the abnormally altered N6-methyladenosine (m6A) modification in eukaryotic cells under environmental pollutants exposure. Arsenic is an environmental metalloid and can cause severe symptoms in human mainly through drinking water. However, there is no specific treatment for its toxic effects due to the uncovered mechanisms. We previously revealed that exposure to arsenic increased the level of m6A via down-regulation of FTO, which might serve as a potential target for intervention against arsenic-related disorders. In this study, our results demonstrated that chronic exposure to arsenic significantly disrupted the intestinal barrier and microenvironment. Also, this administration resulted in the enhancement of m6A modification and the reduction of FTO expression in the intestine. By using both CRISPR/Cas9-based FTO knock-in strategy and adeno-associated virus (AAV)-mediated overexpression of FTO in the intestine, we established for the first time that up-regulation of FTO remarkably ameliorated arsenic-induced disruption of intestinal barriers and altered microenvironment of mice. We also firstly identified a dominant gut microbial species, Desulfovibrio fairfieldensis, which was sharply reduced in arsenic-exposed mice, was able to proceed arsenic-induced neurobehavioral impairments by declining the levels of its major metabolite hydrogen sulfide. Administration of Desulfovibrio fairfieldensis could significantly alleviate the neurotoxicity of arsenic. Intriguingly, the beneficial effects of FTO against arsenic neurotoxicity possibly occurred through a novel gut-brain communication via Desulfovibrio fairfieldensis and its produced hydrogen sulfide. Collectively, these findings will provide new ideas for understanding the mechanisms of arsenic-induced toxic effects from a gut-brain communication perspective, and will assist the development of explicit intervention strategy via regulation of a new potential target FTO for prevention and treatment against arsenic-related both intestinal and neurological disorders.

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.

Potential therapeutic applications of medical gases in cancer treatment

Medical gases were primarily used for respiratory therapy and anesthesia, which showed promising potential in the cancer therapy. Several physiological and pathological processes were affected by the key gases, such as oxygen, carbon dioxide, nitric oxide, hydrogen sulfide, and carbon monoxide. Oxygen targets shrinking the tumor via hyperbaric oxygen therapy, and once combined with radiation therapy it enhances its effect. Nitric oxide has both anti- and pro-tumor effects depending on its level; at high doses, it triggers cell death while at low doses it supports cancer growth. The same concept is applied to hydrogen sulfide which promotes cancer growth by enhancing mitochondrial bioenergetics and supporting angiogenesis at low concentrations, while at high concentrations it induces cancer cell death while sparing normal cells. Furthermore, carbon dioxide helps induce apoptosis and improve oxygenation for cancer treatments by increasing the release of oxygen from hemoglobin. Moreover, high-dose carbon monoxide gas therapy has demonstrated significant tumor reductions in vivo and is supported by nanomedicine and specialized medicines to boost its delivery to tumor cells and the availability of hydrogen peroxide. Despite the promising potentials of these gases, several challenges remain. Gas concentrations should be regulated to balance pro-tumor and anti-tumor effects for gases such as nitric oxide and hydrogen sulfide. Furthermore, effective delivery systems, such as nanoparticles, should be developed for targeted therapy.

Effect of hydrogen sulfide on alpha-synuclein aggregation and cell viability

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder characterized by nigrostriatal degeneration and aggregation of α-synuclein (α-Syn) with accumulation of insoluble aggregates in Lewy bodies. Familial mutations in α-Syn are associated with the development of PD. Accumulation of insoluble aggregates results in neuronal toxicity. Identification of compounds that inhibit seeding activity of α-Syn is of great importance. Here we investigate the potential of H2S donor, sodium hydrosulfide (NaHS), to inhibit α-Syn aggregation. We examined the effect of NaHS on fibril growth kinetics and the structural change of α-Syn fibrils formed by self-seeding and cross-seeding of wild-type (wt) and PD familial α-Syn mutations. NaHS slowed both self- and cross-seeded A53T α-Syn fibril formation but not wild-type fibril formation. We observed a decrease in the formed fibril length in vitro. We examined the effect on fibril formation within cells. NaHS significantly reduced the number and filament length of formed oligomers in an α-Syn overexpressing cell model. Furthermore, NaHS rescued viability of A53T α-Syn overexpressing cells seeded with wt- and mutant preformed fibrils. These results support a conformation-specific effect of hydrogen sulfide on alpha-synuclein aggregation and cell viability which deserves further exploration for therapeutic potential.

Simple Strategy to Develop Multifunctional NIR Fluorescent Probes for Simultaneous Identification of H2S and SO2

H2S and SO2 have been considered as important gaseous signaling molecules in biological systems, functioning as regulatory roles in many physiological processes of organisms. To better understand the crosstalk and synergetic effects between H2S and SO2 in biological systems, developing a single fluorescent probe for dual-channel fast detection of H2S and SO2 is highly urgent. We herein report a simple strategy to develop multifunctional near-infrared (NIR) fluorescent probes for simultaneous identification of H2S and SO2. Based on the idea of modulating the reactivity of the benzopyrylium core with electron donors, two new NIR fluorescent probes (SW1 and SW2) were synthesized and evaluated. The probe SW2 could not only rapidly sense H2S and SO2 with different fluorescence signals but also be used as a reversible probe to investigate the flux of H2O2 and SO2. Moreover, SW2 was successfully applied in visualizing H2S and SO2 in living cells and mice. These results suggest that SW2 could serve as a useful tool in understanding the complex relationships between H2S and SO2 in biological systems.

Shexiang Tongxin Dropping Pills attenuate ischemic microvascular dysfunction via suppressing P66Shc-mediated mitochondrial respiration deficits

ETHNOPHARMACOLOGICAL RELEVANCE

Ischemic stroke (IS) disrupts mitochondrial energy metabolism, leading to cerebral microvascular dysfunction (CMD). Shexiang Tongxin Dropping Pills (STDP) is a traditional Chinese medicinal formulation that has been clinically used for treating microcirculatory dysfunction. We have previously reported its ability to improve cerebral microcirculatory abnormalities. Nevertheless, the protective effects of STDP on cerebral microvascular mitochondria in the context of energy metabolism repair remain underinvestigated.

AIM OF THE STUDY

This study aims to investigate the potential mechanisms by which STDP ameliorates IS-induced CMD through the restoration of mitochondrial function.

MATERIALS AND METHODS

An ischemic stroke/reperfusion model was established by occluding and subsequently reperfusing the middle cerebral artery (MCAO/R) in C57BL/6 J mice. Laser speckle contrast imaging, Y-maze, rotarod tests and TTC staining were employed to evaluate the anti-ischemic stroke effects of STDP. Histological examination of cell adhesion proteins (ICAM 1, VCAM 1) and tight junction proteins (VE-cadherin, occludin) was conducted to assess the effects of STDP on the cerebral microvascular endothelium. In vitro, a bEnd.3 cell model was established through oxygen-glucose deprivation followed by reoxygenation (OGD/R). The cytoprotective capability of STDP was assessed by quantifying endothelial permeability, reactive oxygen species (ROS) levels, and cell viability. Mendelian randomization (MR) analysis and bioinformatic studies were performed to elucidate the causal associations between mitochondrial biological function and IS. Mitochondrial membrane potential (MMP) was assessed using a tetramethylrhodamine ethyl ester perchlorate fluorescent probe, while ATP production was quantified using a commercially available assay kit. Mitochondrial respiration was evaluated by measuring the oxygen consumption rate (OCR). Finally, the verification of important targets in mouse brain slices and bEnd.3 cells was conducted through immunoblotting and immunofluorescence.

RESULTS

STDP significantly restored cerebral blood flow and neurological function, and reduced infarct volume in MCAO/R mice. Furthermore, STDP markedly alleviated inflammation and hyperpermeability of the cerebral microvascular endothelium in MCAO/R mice, as evidenced by the suppression of ICAM-1 and VCAM-1 expression, along with the upregulation of VE-cadherin and occludin protein levels. Moreover, STDP not only mitigated hyperpermeability and excessive production of ROS induced by OGD/R in bEnd.3 cells but also enhanced the protective effects of the ROS scavenger N-acetylcysteine on bEnd.3 cells. Results of MR analysis and bioinformation studies demonstrated that the disruption of mitochondrial respiration is a critical pathogenic factor in IS-induced CMD. Our data confirmed that STDP effectively restored MMP and ATP production in OGD/R-treated bEnd.3 cells. Furthermore, STDP significantly enhanced basal respiration, maximal OCR, and spare respiratory capacity in bEnd.3 cells compared to the OGD/R group. Mechanistically, STDP markedly increased endothelial cystathionine γ-lyase (CSE)-mediated hydrogen sulfide (H2S) production and S-sulfhydration of P66shc, resulting in reduced protein expression and phosphorylation levels of P66Shc. This inhibition prevented its translocation into mitochondria, thereby restoring mitochondrial respiration.

CONCLUSION

STDP facilitated CSE expression and promoted H2S production, contributing to the inactivation of P66shc by suppressing its expression and increasing its sulfhydration. This process impeded P66Shc translocation to mitochondria, subsequently restoring mitochondrial respiration and alleviating IS-induced cerebral microvascular endothelial dysfunction.

The mammalian longevity associated acetylome

Despite extensive studies at the genomic, transcriptomic and metabolomic levels, the underlying mechanisms regulating longevity are incompletely understood. Post-translational protein acetylation is suggested to regulate aspects of longevity. To further explore the role of acetylation, we develop the PHARAOH computational tool based on the 100-fold differences in longevity within the mammalian class. Analyzing acetylome and proteome data across 107 mammalian species identifies 482 and 695 significant longevity-associated acetylated lysine residues in mice and humans, respectively. These sites include acetylated lysines in short-lived mammals that are replaced by permanent acetylation or deacetylation mimickers, glutamine or arginine, respectively, in long-lived mammals. Conversely, glutamine or arginine residues in short-lived mammals are replaced by reversibly acetylated lysine in long-lived mammals. Pathway analyses highlight the involvement of mitochondrial translation, cell cycle, fatty acid oxidation, transsulfuration, DNA repair and others in longevity. A validation assay shows that substituting lysine 386 with arginine in mouse cystathionine beta synthase, to attain the human sequence, increases the pro-longevity activity of this enzyme. Likewise, replacing the human ubiquitin-specific peptidase 10 acetylated lysine 714 with arginine as in short-lived mammals, reduces its anti-neoplastic function. Overall, in this work we propose a link between the conservation of protein acetylation and mammalian longevity.

Intracellular hydrogen sulfide induces stress granule formation and translational repression through eIF2α phosphorylation

Acute exposure to high concentrations of hydrogen sulfide (H2S), a toxic gaseous substance, can cause potentially lethal respiratory damages. Stress granules (SGs) are cytoprotective membrane-less intracellular organelles formed transiently in response to various stressors. We examined SG formation and the underlying molecular mechanism following exposure to high concentrations of H2S using human bronchial BEAS-2B (BEAS) and GFP-tagged G3BP1-stably transfected CHO cells. We first examined the changes in intracellular H2S concentration by NaHS exposure. Qualitative and quantitative analyses revealed that intracellular H2S levels rapidly increased after NaHS exposure and accumulated in cells dose dependently. In terms of the response to H2S taken up after exposure to 2.5-10 mM NaHS, both cell lines formed discrete SG assemblies within 1 h. SG formation induced by NaHS exposure was enhanced by treatment with glutathione (GSH) or thioredoxin (Trx) inhibitor but suppressed by treatment with a PERK inhibitor or integrated stress response inhibitor. Levels of phosphorylation of eIF2 α, which is essential for canonical SG formation, were significantly and dose-dependently increased in NaHS-exposed BEAS cells. Phosphorylation of eIF2α was further increased by GSH or Trx inhibitor treatment. These results suggest that GSH and Trx play protective roles in H2S-induced SG formation. PERK, a kinase of eIF2α, might activate the pathway partially. Levels of newly synthesized proteins were markedly reduced in NaHS-exposed cells. In summary, when humans inhale high concentrations of H2S, H2S is rapidly taken up by pulmonary cells and induces SG formation and translational repression via eIF2α phosphorylation, thereby protecting against cell death.

Sodium aescinate induces hepatotoxicity through apoptosis and ferroptosis by inhibiting the Nrf2/CTH pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The seed of Aesculus wilsonii Rehd., also known as Suoluozi in China, is a traditional Chinese herb included in the Pharmacopoeia of China (2020). Sodium aescinate (SA) is derived from the Aesculus wilsonii Rehd.'s seeds and is extensively used in clinical practice.

AIM OF THE STUDY

The study investigated the involvement of the Nrf2/CTH pathway in SA-induced hepatotoxicity and explored potential strategies for alleviating SA-induced liver damage.

MATERIALS AND METHODS

The ICR mice and AML12 mouse hepatocytes were exposed to SA. The levels of Fe2+, cysteine (Cys), glutathione (GSH), hydrogen sulfide (H2S), ROS, lipid peroxides and caspase-3 activity were assessed. The effects of SA on signaling pathways related to ferroptosis and apoptosis were examined. Furthermore, genetic modification or agonists of Nrf2 and CTH were co-treated with SA.

RESULTS

SA triggered ferroptosis and apoptosis in AML12 cells and mouse livers, characterized by a decline in Cys, GSH, and H2S levels, as well as accumulation of Fe2+, ROS and lipid peroxides, mitochondrial dysfunction, and chromatin condensation. SA decreased Nrf2, CTH, and Bcl-2 levels, elevated Bax levels, and activated caspase-9/3. Overexpression of Nrf2 or CTH, or NAC supplementation alleviated SA-induced ferroptosis by upregulating Cys and GSH levels. Overexpression of Nrf2 or CTH, or NaHS supplementation increased H2S levels, which reduced the interaction between p616-Drp1 and VDAC1 by enhancing Drp1 S-sulfenylation, thereby alleviating SA-induced mitochondrial-dependent apoptosis. Furthermore, DMF or Met mitigated SA-induced hepatotoxicity by activating the Nrf2/CTH pathway.

CONCLUSIONS

SA triggers oxidative stress, mitochondrial dysfunction, apoptosis, and ferroptosis, ultimately leading to liver damage by suppressing the Nrf2/CTH pathway.

A pyrene-based fluorescent sensor for the discrimination and estimation of hydrazine and hydrogen sulfide and its application in assessing food spoilage

Hydrazine (N2H4) and hydrogen sulfide (H2S) are environmental contaminants that adversely affect human health. Fluorescence-based detection methods for these analytes utilize their nucleophilicity and reducing ability. Therefore, fluorescent sensors capable of detecting and distinguishing hydrazine and H2S are highly beneficial. With this objective, we synthesized a pyrene-based fluorophore, 2-(pyren-1-ylmethylene)malononitrile (PMM), to detect and differentiate hydrazine and H2S in various media and real samples. Using colorimetric and fluorimetric techniques, we examined the reaction of PMM with these analytes. Although they underwent 1,4-addition with PMM to generate a ratiometric response, the reactions followed different pathways, leading to two different products with distinct emission profiles. The reaction of PMM with hydrazine yielded the corresponding azine Py-Az, resulting in a ratiometric fluorescence response characterized by the emergence of a new peak at 458 nm and a simultaneous reduction in emission intensity at 540 nm. PMM was able to detect hydrazine in soil and water as well as its vapors. Likewise, PMM successfully detected and quantified H2S in solution and human blood serum. The addition of H2S to PMM solution resulted in a ratiometric response characterized by an increase in the intensity of pyrene monomer emission, accompanied by a concurrent decrease in emission at 540 nm. Using PMM, we also demonstrated the sequential detection of hydrazine, Cu2+, and H2S. This detection utilizes the affinity of Py-Az for Cu2+ and the subsequent demetallation of the Py-Az-Cu complex facilitated by H2S. Overall, PMM generated a ratiometric response to hydrazine, a turn-on response to Cu2+, and a turn-off response to H2S. Given that PMM exhibited a ratiometric response to H2S, PMM-coated filter paper strips were also employed to assess the freshness of protein-rich foods such as fish and meat.

Phototherapy in cancer treatment: strategies and challenges

Phototherapy has emerged as a promising modality in cancer treatment, garnering considerable attention for its minimal side effects, exceptional spatial selectivity, and optimal preservation of normal tissue function. This innovative approach primarily encompasses three distinct paradigms: Photodynamic Therapy (PDT), Photothermal Therapy (PTT), and Photoimmunotherapy (PIT). Each of these modalities exerts its antitumor effects through unique mechanisms-specifically, the generation of reactive oxygen species (ROS), heat, and immune responses, respectively. However, significant challenges impede the advancement and clinical application of phototherapy. These include inadequate ROS production rates, subpar photothermal conversion efficiency, difficulties in tumor targeting, and unfavorable physicochemical properties inherent to traditional phototherapeutic agents (PTs). Additionally, the hypoxic microenvironment typical of tumors complicates therapeutic efficacy due to limited agent penetration in deep-seated lesions. To address these limitations, ongoing research is fervently exploring innovative solutions. The unique advantages offered by nano-PTs and nanocarrier systems aim to enhance traditional approaches' effectiveness. Strategies such as generating oxygen in situ within tumors or inhibiting mitochondrial respiration while targeting the HIF-1α pathway may alleviate tumor hypoxia. Moreover, utilizing self-luminescent materials, near-infrared excitation sources, non-photoactivated sensitizers, and wireless light delivery systems can improve light penetration. Furthermore, integrating immunoadjuvants and modulating immunosuppressive cell populations while deploying immune checkpoint inhibitors holds promise for enhancing immunogenic cell death through PIT. This review seeks to elucidate the fundamental principles and biological implications of phototherapy while discussing dominant mechanisms and advanced strategies designed to overcome existing challenges-ultimately illuminating pathways for future research aimed at amplifying this intervention's therapeutic efficacy.

A superoxide anion responsive and self-reporting fluorescent H2S donor for the treatment of diabetic wound

Superoxide anion (O2•-) not only serves as a critical precursor for numerous damaging reactive oxygen species (ROS), but also is implicated in a variety of diseases, including cancer, cardiovascular disorders, and diabetes. Consequently, reducing the levels of superoxide anions and alleviating oxidative stress are of paramount importance. Conversely, hydrogen sulfide (H2S), recognized as a significant biological signaling molecule, plays vital roles in protecting mammalian cells from oxidative damage and promoting tissue regeneration. In this study, we reported a novel superoxide anion-responsive H2S donor (HSD-SO-B) designed to scavenge O2•- and produce H2S concurrently. This H2S donor exhibits several advantages: (1) rapid response to superoxide anions (O2•-) with remarkable selectivity over competing species (2) generating H2S while scavenging superoxide anions (3) producing ratiometric fluorescence for both visualization and quantification of H2S release. Moreover, this O2•--responsive, self-immolative fluorescent H2S donor has shown significant therapeutic and reparative effects on the diabetic wound model in mice.

Hydrogen Sulfide (H2S- or H2Sn-Polysulfides) in Synaptic Plasticity: Modulation of NMDA Receptors and Neurotransmitter Release in Learning and Memory

Hydrogen sulfide (H2S) has emerged as a pivotal gaseous transmitter in the central nervous system, influencing synaptic plasticity, learning, and memory by modulating various molecular pathways. This review examines recent evidence regarding how H2S regulates NMDA receptor function and neurotransmitter release in neuronal circuits. By synthesizing findings from animal and cellular models, we investigate the impacts of enzymatic H2S production and exogenous H2S on excitatory synaptic currents, long-term potentiation, and intracellular calcium signaling. Data suggest that H2S interacts directly with NMDA receptor subunits, altering receptor function and modulating neuronal excitability. Simultaneously, H2S promotes the release of neurotransmitters such as glutamate and GABA, shaping synaptic dynamics and plasticity. Furthermore, reports indicate that disruptions in H2S metabolism contribute to cognitive impairments and neurodegenerative disorders, underscoring the potential therapeutic value of targeting H2S-mediated pathways. Although the precise mechanisms of H2S-induced changes in synaptic strength remain elusive, a growing body of evidence positions H2S as a significant regulator of memory formation processes. This review calls for more rigorous exploration into the molecular underpinnings of H2S in synaptic plasticity, paving the way for novel pharmacological interventions in cognitive dysfunction.

Transcriptional memories mediate the plasticity of sulfide stress responses to enable acclimation in Urechis unicinctus

To cope with environmental stresses, organisms often adopt a memory response upon primary stress exposure to facilitate a quicker and/or stronger reaction to recurring stresses. Somatic stress memory is essential in dealing with contemporary stress. The earliest sign of somatic stress memory is a change in gene transcription levels, which alters physiology and phenotype to better cope with stress. Sulfide is a common environmental pollutant; however, some organisms have successfully colonized sulfur-rich environments. Whether stress memory plays important role in sulfide stress adaptation remains unclear. In this study, to determine whether Urechis unicinctus, a sulfur-tolerant organism, retains the memory of previous sulfide stress, we simulated a repetitive sulfide stress/recovery system. The results showed that the tolerance of U. unicinctus to sulfide stress was significantly increased after priming with 50 µM sulfide. Further, transcriptional memory genes (TMGs) involved in regulating sulfide stress memory were identified, classified according to their expression patterns, and functionally analyzed. TMGs involved in sulfide metabolism, sugar metabolism, and protein homeostasis pathway showed an enhanced response, whereas those related to DNA repair pathway demonstrated a modified response pattern. Our study indicated that U. unicinctus retains memory of sulfide stress priming, which mediates plasticity to accelerate sulfide stress adaptation.

Modeling the Interactions Between Chemicals and Proteins to Predict the Health Consequences of Air Pollution

The impacts of air pollution on human health have become a major concern, especially with rising greenhouse gas emissions and urban development. This study investigates the molecular mechanisms using the STITCH 4.0 and STRING 9.0 databases to analyze the interaction networks (PCI and PPI) associated with two air pollutants: carbon monoxide and hydrogen sulfide. The functional and pathway analysis related to these pollutants were performed by OmicsBox v.3.0. Additionally, critical proteins and their essential pathways were also identified by the Cytoscape networking tool v.3.10.3. AutoDock vina was employed to hypothetically determine the direct interactions of CO and H2S with the proteins that were found by STITCH. This study revealed that CO and H2S interacted with the different biological processes related to human health, including erythropoiesis, oxidative stress, energy production, amino acids metabolism, and multiple signaling pathways associated with respiratory, cardiovascular, and neurological functions. Six essential proteins were identified based on their degree of centrality, namely, FECH, HMOX1, ALB, CTH, CBS, and CBSL, which regulate various Reactome and KEGG pathways. Molecular docking analysis revealed that CO exhibited a strong interaction with ADI1, demonstrating a binding affinity of -1.9 kcal/mL. Alternately, the binding energy associated with the H2S interaction was notably weak (below -0.9 kcal/mL). This present research highlights the necessity for ongoing investigation into the molecular effects of air pollution to guide public health policies and interventions.

Development of a Rapid-Response Fluorescent Probe for H2S: Mechanism Elucidation and Biological Applications

Hydrogen sulfide (H2S) is an important signaling molecule involved in various physiological and pathological processes, making its accurate detection in biological systems highly desirable. In this study, two fluorescent probes (M1 and M2) based on 1,8-naphthalimide were developed for H2S detection via a nucleophilic aromatic substitution. M1 demonstrated high sensitivity and selectivity for H2S in aqueous media, with a detection limit of 0.64 µM and a strong linear fluorescence response in the range of 0-22 µM of NaHS. The reaction kinetics revealed a rapid response, with a reaction rate constant of 7.56 × 102 M-1 s-1, and M1 was most effective in the pH range of 6-10. Mechanism studies using 1H NMR titration confirmed the formation of 4-hydroxyphenyl-1,8-naphthalimide as the product of H2S-triggered nucleophilic substitution. M1 was applied in MDA-MB-231 cells for cell imaging, in which M1 provided significant fluorescence enhancement upon NaHS treatment, confirming its applicability for detecting H2S in biological environments. In comparison, M2, designed with extended conjugation for red-shifted emission, exhibited weaker sensitivity due to the reduced stability of its naphtholate product and lower solubility. These results demonstrate that M1 is a highly effective and selective fluorescent probe for detecting H2S, providing a valuable resource for investigating the biological roles of H2S in health and disease.

Why Symptoms Linger in Quiescent Crohn's Disease: Investigating the Impact of Sulfidogenic Microbes and Sulfur Metabolic Pathways

INTRODUCTION

Even in the absence of inflammation, persistent symptoms in patients with Crohn's disease (CD) are prevalent and worsen quality of life. We previously demonstrated enrichment in sulfidogenic microbes in quiescent Crohn's disease patients with (qCD + S) vs without persistent GI symptoms (qCD-S). Thus, we hypothesized that sulfur metabolic pathways would be enriched in stool while differentially abundant microbes would be associated with important sulfur metabolic pathways in qCD + S.

METHODS

We performed a multicenter observational study nested within SPARC IBD. Quiescent inflammation was defined by fecal calprotectin level < 150 mcg/g. Persistent symptoms were defined by CD-PRO2. Active CD (aCD) and non-IBD diarrhea-predominant irritable bowel syndrome (IBS-D) were included as controls.

RESULTS

Thirty-nine patients with qCD + S, 274 qCD-S, 21 aCD, and 40 IBS-D underwent paired shotgun metagenomic sequencing and untargeted metabolomic profiling. The fecal metabolome in qCD + S was significantly different relative to qCD-S and IBS-D but not aCD. Patients with qCD + S were enriched in sulfur-containing amino acid pathways, including cysteine and methionine, as well as serine, glycine, and threonine. Glutathione and nicotinate/nicotinamide pathways were also enriched in qCD + S relative to qCD-S, suggestive of mitochondrial dysfunction, a downstream target of H2S signaling. Multi-omic integration demonstrated that enriched microbes in qCD + S were associated with important sulfur metabolic pathways. Bacterial sulfur metabolic genes, including CTH, isfD, sarD, and asrC, were dysregulated in qCD + S. Finally, sulfur metabolites with and without sulfidogenic microbes showed good accuracy in predicting the presence of qCD + S.

DISCUSSION

Microbial-derived sulfur pathways and downstream mitochondrial function are perturbed in qCD + S, which implicate H2S signaling in the pathogenesis of this condition. Future studies will determine whether targeting H2S pathways results in improved quality of life in qCD + S.

Versatile nanomaterials used in combatting biofilm infections

Microbial infections are a pressing global health issue, exacerbated by the rise of antibiotic-resistant bacteria due to widespread antibiotic overuse. This resistance diminishes the effectiveness of current treatments, intensifying the need for new antimicrobial agents and innovative drug delivery strategies. Nanotechnology presents promising solutions, leveraging the unique properties of nanomaterials such as tunable optical and electronic characteristics, nanoscale size, and high surface-to-volume ratios. These features enhance their effectiveness as innovative antimicrobial agents and versatile drug delivery systems. This minireview classifies antimicrobial nanomaterials into four categories based on their mechanisms of action: thermal generation, reactive oxygen species generation, gas generation, and nanocarrier systems such as liposomes, polymersomes, and metal-organic frameworks. Uniquely, this review integrates a comparative analysis of these mechanisms, highlighting their relative advantages, limitations, and applications across diverse microbial targets. Additionally, it identifies emerging trends in the field, providing a forward-looking perspective on how recent advancements in nanotechnology can be leveraged to address unmet clinical needs. Finally, this article discusses future directions and emerging opportunities in antimicrobial nanotechnology.

Molecular regulation of cardiomyocyte functions by exogenous hydrogen sulphide in Atlantic salmon (Salmo salar)

Hydrogen sulphide (H2S) is known to regulate various physiological processes, but its role in fish cardiac function, especially at the molecular level, is poorly understood. This study examined the molecular functions of exogenous H2S, using sodium hydrosulphide (NaHS) as a donor, on Atlantic salmon cardiomyocytes. NaHS concentrations of 10 to 160 μM showed limited cytotoxicity and no impact on cell proliferation, though higher doses increased ATP activity. Menadione and NaHS administered separately or sequentially differentially regulated the expression of antioxidant response and sulphide detoxification genes. Transcriptomic analysis over 24, 48, 72, and 120 h revealed differential gene expression related to metabolic recovery. Enriched Gene Ontology terms at 24 h included processes like cell signalling and lipid metabolism, shifting to lipid metabolism and ribosomal processes by 48 h. By 120 h, xenobiotic metabolism and RNA synthesis were prominent. The study highlights NaHS-induced metabolic adjustments, particularly in lipid metabolism, in Atlantic salmon cardiomyocytes.

Pyridoxal-5-phosphate mitigates age-related metabolic imbalances in the rat heart through the H2S/AKT/GSK3β signaling axis

Pyridoxal-5-phosphate (PLP) enhances the synthesis of endogenous hydrogen sulfide, a potent regulator of cell metabolism. We used 24-month-old rats to investigate the PLP mitoprotective function in the aging heart. We demonstrated improvement of mitochondrial bioenergetic functions, inhibition of mPTP opening after PLP administration. Moreover, PLP treatment increased glucose consumption and utilization, decreased lipid transport into the cells, but increased fatty acid β-oxidation, providing sufficient energy. An ECG study showed a significant improvement in cardiac function in PLP-treated old rats. Our data suggest that PLP may exert its effect through the H2S/AKT/GSK3β axis with further targeting of the Sirt1/PGC-1α signaling pathway.

CSE/H2S Signaling Pathways in Enhancing Muscle Function and Insulin Sensitivity During Exercise

Exercise plays a crucial role in maintaining metabolic health, enhancing muscle function, and improving insulin sensitivity, thereby preventing metabolic diseases such as type 2 diabetes. Emerging evidence highlights the significance of the cystathionine γ-lyase (CSE)/hydrogen sulfide (H2S) signaling pathway as a pivotal regulator in the molecular and physiological adaptations induced by exercise. This review comprehensively examines the biosynthesis and metabolism of H2S, its distribution in different muscle tissues, and the mechanisms by which CSE/H2S influences muscle contraction, repair, and protein synthesis. Additionally, it explores how CSE/H2S modulates insulin signaling pathways, glucose uptake, and lipid metabolism, thereby enhancing insulin sensitivity. The potential of H2S donors as exercise supplements is also discussed, highlighting their ability to improve exercise performance and metabolic health. Current research advancements, including the application of multi-omics approaches, are reviewed to provide a deeper understanding of the complex molecular networks involved. Furthermore, the challenges and future directions in CSE/H2S research are addressed, emphasizing the need for further mechanistic studies and clinical applications. This review underscores the therapeutic potential of targeting the CSE/H2S pathway to optimize the benefits of exercise and improve metabolic health.

Fluorescent probes for detecting and imaging mitochondrial hydrogen sulfide

Hydrogen sulfide (H2S) is a potent redox-active signaling molecule commonly dysregulated in disease states. The production of H2S and its involvement in various pathological conditions associated with mitochondrial dysfunction have extensively documented. During stress, cystathionine gamma-lyase and cystathionine beta-synthase in cytosol are copiously translocated into the mitochondria to boost H2S production, confirming its pivotal role in mitochondrial activities. However, little study has been done on H2S levels in tissues, cells and organelles, mainly due to the absence of precise and accurate detection tools. Thus, there is an urgent need to determine and monitor the levels of H2S in these important organelles. Fluorescent probes are efficient tools for detecting and monitoring various important biomolecules including biological thiols. The development of fluorescent probes is a multi-pronged approach which involves coupling fluorophores with responsive sites. The use of fluorescent probes for monitoring mitochondrial H2S levels has recently received widespread attention, resulting in numerous publications depicting their synthesis, mechanism of action, application, and potential challenges. Fluorescent probes offer precise and timely results, high sensitivity and selectivity, low biotoxicity, and minimal background interference. In this review, we aim to report designs of such probes, reaction mechanisms and their application in detecting mitochondrial H2S levels. Fluorescent probes can help uncover physio/pathological levels of H2S in essential organelles, its interactions with various biomarkers and associated consequences in biological systems.

H2S-Scavenging Hydrogel Alleviating Mitochondria Damage to Control Periodontitis

H2S, as a typical metabolite of periodontal pathogens, exhibits a clear positive correlation with the occurrence and development of periodontitis. H2S at physiological concentrations can regulate many biological processes. However, excess H2S in the periodontal pocket can trigger secretion of proinflammatory cytokines, cause oxidative stress, and result in mitochondrial damage and cell death in human gingival fibroblasts, exacerbating periodontitis development and periodontal tissue destruction. Worse, H2S facilitates bacteria survival and proliferation by maintaining bacterial redox balance and enhancing antibiotic resistance. Unfortunately, scavenging H2S during periodontitis treatment is usually ignored. Herein, a kind of hyaluronic acid methacryloyl/ZnO (HMZ) composite hydrogel with an H2S-scavenging ability was prepared to enhance periodontitis treatment. The HMZ hydrogel possessed good injectability and cytocompatibility and was able to remove H2S by a reaction with ZnO. As a result, the HMZ hydrogel was able to increase cell viability from 13% to 120% for human gingival fibroblasts and 22% to 94% for human periodontal ligament fibroblasts at 48 h, restore mitochondrial homeostasis, and alleviate cGAS-STING signaling pathway-mediated inflammation. Meanwhile, the HMZ hydrogel showed satisfactory antibacterial properties and efficiency of plaque biofilm removal. The in vivo results further confirmed that HMZ hydrogel decreased the concentration of H2S within the periodontal pocket from 0.7 to 0.8 mM to the normal level (0.3 to 0.4 mM), killed the bacteria in the periodontal tissues, inhibited osteoclast activity, relieved excess inflammation, and decreased the vertical distance between the cementoenamel junction and the alveolar bone crest from 1,175 µm to 798 µm on the 7th day and from 1,075 µm to 693 µm on the 14th day, achieving efficient periodontal bone regeneration. In brief, an H2S scavenging-based promising strategy was developed to enhance the therapeutic efficiency of periodontitis.

UW supplementation with AP39 improves liver viability following static cold storage

Static cold storage of donor livers at 4 °C incompletely arrests metabolism, ultimately leading to decreases in ATP levels, oxidative stress, cell death, and organ failure. Hydrogen Sulfide (H2S) is an endogenously produced gas, previously demonstrated to reduce oxidative stress, reduce ATP depletion, and protect from ischemia and reperfusion injury. H2S is difficult to administer due to its rapid release curve, resulting in cellular death at high concentrations. AP39, a mitochondrially targeted, slow-release H2S donor, has been shown to reduce ischemia-reperfusion injury in hearts and kidneys. Thus, we investigated whether the addition of AP39 during 3-day static cold storage can improve liver graft viability. At the end of storage, livers underwent six hours of acellular normothermic machine perfusion, a model of transplantation. During simulated transplantation, livers stored with AP39 showed reduced resistance, reduced cellular damage (ALT and AST), and reduced apoptosis. Additionally, bile production and glucose, as well as energy charge were improved by the addition of AP39. These results indicate that AP39 supplementation improves liver viability during static cold storage.

The double face of licorice-kansui herb pair: Cure or curse, depending on the combining ratio and mediated by hydrogen sulfide

BACKGROUND

The safety and efficacy of herbal medicines including traditional Chinese medicine (TCM) has been one of the major scientific problems in the medical field. In TCM prescriptions, reasonable herbal combinations bring stronger efficacy and low risk of toxicity. However, the rules and mechanisms for herbal combinations are far from complete understood yet.

PURPOSE

In this study, we investigated the efficacy-toxicity transformation of the licorice-kansui herbal combination under clinical equivalent doses, and study the inside mechanisms.

STUDY DESIGN

Licorice-kansui or glycyrrhetinic acid-kansuinine A combinations of different combining ratio were given to malignant pleural effusion mice as well as the IEC-6 and S-180 cells.

METHODS

The therapeutic and toxic effects were characterized by various indicators; the chemical changes were analyzed by LC-MS method; the role of H2S was also studied through its inhibitors.

RESULTS

Low-proportion of licorice combined with kansui exerted comparable therapeutic effects to cisplatin, by reducing pleural effusion, promoting respiration, increasing urine volume, protecting lung tissue, and inhibiting tumor cells by inducing oxidative stress and apoptosis. On the other hand, high-proportion of licorice combined with kansui had poor therapeutic effect but induced oxidative stress, inflammation and tissue damages, especially to the small intestine. This efficacy-toxicity transformation was also reproduced by the glycyrrhetinic acid-kansuinine A combination on IEC-6 epithelial cells and S-180 tumor cells. The transformation was not simply caused by the in-solution solubilization effects of licorice during co-decocted with kansui. Furthermore, the therapeutic and toxic effects were both highly related to the hydrogen sulfide level and its anabolic enzymes, cystathionine-gamma-lyase (CSE) or cystathionine beta-synthase (CBS), either in tissues or in-vitro cells. By inhibiting CSE or CBS, all the therapeutic or toxic effects were abolished both in-vivo and in-vitro. Moreover, the intestinal sulfide-reducing bacteria Desulfovibrio and body drug-metabolism were also important variants influencing the efficacy-toxicity transformation of licorice-kansui herbal combination.

CONCLUSION

This study comprehensively uncovered the rules of licorice-kansui herbal combination, and for the first time confirmed that H2S plays a crucial role in mediating its efficacy-toxicity transformation. Our study not only supports the reasonable clinical usage of these two herbs but also provide ideas and methods for the study of other herb pairs in TCM prescriptions.

Interaction and regulation of the mitochondrial proteome - in health and disease

INTRODUCTION

Mitochondria contain multiple pathways including energy metabolism and several signaling and synthetic pathways. Mitochondrial proteomics is highly valuable for studying diseases including inherited metabolic disorders, complex and common disorders like neurodegeneration, diabetes, and cancer, since they all to some degree have mitochondrial underpinnings.

AREAS COVERED

The main mitochondrial functions and pathways are outlined, and systematic protein lists are presented. The main energy metabolic pathways are as follows: iron-sulfur cluster synthesis, one carbon metabolism, catabolism of hydrogen sulfide, kynurenines and reactive oxygen species (ROS), and others, described with the aim of laying a foundation for systematic mitochondrial pathway analysis based on proteomics data. The links of the proteins and pathways to functional effects and diseases are discussed. The disease examples are focussed on inherited metabolic disorders, cancer, neurological, and cardiovascular disorders.

EXPERT OPINION

To elucidate the role of mitochondria in health and disease, there is a need for comprehensive proteomics analyses with stringent, systematic data treatment for proper interpretation of mitochondrial pathway data. In that way, comprehensive hypothesis-based research can be performed based on proteomics data.

Novel thiomaleimide-based fluorescent probe with aggregation-induced emission for detecting H2S

It has been well established that Hydrogen sulfide (H2S) is involved in various pathophysiological processes. Therefore, accurate monitoring H2S levels in vitro or vivo is of great significance in biological systems. Herein, we firstly developed a thiomaleimide-based compound MAL-1 bearing aggregation-induced emission characteristic for selective response toward H2S due to its nucleophilicity. The proposed sensor presented prominent sensitivity and selectivity with low detection limit of 75 nM and pseudo-first-order reaction rate constant of 9.65 × 10-2 s-1, as well as low cytotoxicity which works well in recognizing H2S in real samples and visualizing H2S in living cells. Thus, it could be concluded that the novel thiomaleimide-based probe would be a promising tool for assessing intracellular H2S levels.

Harshly Oxidized Activated Charcoal Enhances Protein Persulfidation with Implications for Neurodegeneration as Exemplified by Friedreich's Ataxia

Harsh acid oxidation of activated charcoal transforms an insoluble carbon-rich source into water-soluble, disc structures of graphene decorated with multiple oxygen-containing functionalities. We term these pleiotropic nano-enzymes as "pleozymes". A broad redox potential spans many crucial redox reactions including the oxidation of hydrogen sulfide (H2S) to polysulfides and thiosulfate, dismutation of the superoxide radical (O2-*), and oxidation of NADH to NAD+. The oxidation of H2S is predicted to enhance protein persulfidation-the attachment of sulfur to cysteine residues. Persulfidated proteins act as redox intermediates, and persulfidation protects proteins from irreversible oxidation and ubiquitination, providing an important means of signaling. Protein persulfidation is believed to decline in several neurological disorders and aging. Importantly, and consistent with the role of persulfidation in signaling, the master antioxidant transcription factor Nrf2 is regulated by Keap1's persulfidation. Here, we demonstrate that pleozymes increased overall protein persulfidation in cells from apparently healthy individuals and from individuals with the mitochondrial protein mutation responsible for Friedreich's ataxia. We further find that pleozymes specifically enhanced Keap1 persulfidation, with subsequent increased accumulation of Nrf2 and Nrf2's antioxidant targets.

Quantification of persulfidation on specific proteins: are we nearly there yet?

Hydrogen sulfide (H2S) played a pivotal role in the early evolution of life on Earth before the predominance of atmospheric oxygen. The legacy of a persistent role for H2S in life's processes recently emerged through its discovery in modern biochemistry as an endogenous cellular signalling modulator involved in numerous biological processes. One major mechanism through which H2S signals is protein cysteine persulfidation, an oxidative post-translational modification. In recent years, chemoproteomic technologies have been developed to allow the global scanning of protein persulfidation targets in mammalian cells and tissues, providing a powerful tool to elucidate the broader impact of altered H2S in organismal physiological health and human disease states. While hundreds of proteins were confirmed to be persulfidated by global persulfidome methodologies, the targeting of specific proteins of interest and the investigation of further mechanistic studies are still underdeveloped due to a lack of stringent specificity of the methods and the inherent instability of persulfides. This review provides an overview of the processes of endogenous H2S production, oxidation, and signalling and highlights the application and limitations of current persulfidation labelling approaches for investigation of this important evolutionarily conserved biological switch for protein function.

Hydrogen sulfide mitigates mitochondrial dysfunction and cellular senescence in diabetic patients: Potential therapeutic applications

Diabetes induces a pro-aging state characterized by an increased abundance of senescent cells in various tissues, heightened chronic inflammation, reduced substance and energy metabolism, and a significant increase in intracellular reactive oxygen species (ROS) levels. This condition leads to mitochondrial dysfunction, including elevated oxidative stress, the accumulation of mitochondrial DNA (mtDNA) damage, mitophagy defects, dysregulation of mitochondrial dynamics, and abnormal energy metabolism. These dysfunctions result in intracellular calcium ion (Ca2+) homeostasis disorders, telomere shortening, immune cell damage, and exacerbated inflammation, accelerating the aging of diabetic cells or tissues. Hydrogen sulfide (H2S), a novel gaseous signaling molecule, plays a crucial role in maintaining mitochondrial function and mitigating the aging process in diabetic cells. This article systematically explores the specific mechanisms by which H2S regulates diabetes-induced mitochondrial dysfunction to delay cellular senescence, offering a promising new strategy for improving diabetes and its complications.

Emerging roles of hydrogen sulfide-metabolizing enzymes in cancer

Gasotransmitters play crucial roles in regulating many physiological processes, including cell signaling, cellular proliferation, angiogenesis, mitochondrial function, antioxidant production, nervous system functions and immune responses. Hydrogen sulfide (H2S) is the most recently identified gasotransmitter, which is characterized by its biphasic behavior. At low concentrations, H2S promotes cellular bioenergetics, whereas at high concentrations, it can exert cytotoxic effects. Cystathionine β-synthetase (CBS), cystathionine-γ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (3-MST), and cysteinyl-tRNA synthetase 2 (CARS2) are pivotal players in H2S biosynthesis in mammalian cells and tissues. The focus of this review is the regulation of the various pathways involved in H2S metabolism in various forms of cancer. Key enzymes in this process include the sulfide oxidation unit (SOU), which includes sulfide:quinone oxidoreductase (SQOR), human ethylmalonic encephalopathy protein 1 (hETHE1), rhodanese, sulfite oxidase (SUOX/SO), and cytochrome c oxidase (CcO) enzymes. Furthermore, the potential role of H2S methylation processes mediated by thiol S-methyltransferase (TMT) and thioether S-methyltransferase (TEMT) is outlined in cancer biology, with potential opportunities for targeting them for clinical translation. In order to understand the role of H2S in oncogenesis and tumor progression, one must appreciate the intricate interplay between H2S-synthesizing and H2S-catabolizing enzymes.

Organelle-Specific Smart Supramolecular Materials for Bioimaging and Theranostics Application

In cellular environments, certain synthetic molecules can form nanostructures via self-assembly, impacting molecular imaging, and biomedical applications. Control over the formation of these self-assembled nanostructures in subcellular organelle is challenging. By the action of stimuli, either present in the cellular environment or applied externally, in situ generation of molecular precursors can lead to accumulation and supramolecular nanostructure formation, resulting in efficient bioimaging. Here, we summarize smart fluorophore-based ordered nanostructure preparation at specific organelles for efficient bioimaging and therapeutic application towards cancer theranostics. We also present challenges and an outlook regarding intercellular self-assembly for theranostics application. Altogether, smart nanostructured materials with fluorescence read-outs at specific subcellular compartments would be beneficial in synthetic biology and precision therapeutics.

Orthogonal Persulfide Generation through Precision Tools Provides Insights into Mitochondrial Sulfane Sulfur

The sulfane sulfur pool, comprised of persulfide (RS-SH) and polysulfide (RS-SnH) derived from hydrogen sulfide (H2S), has emerged as a major player in redox biochemistry. Mitochondria, besides energy generation, serve as significant cellular redox hubs, mediate stress response and cellular health. However, the effects of endogenous mitochondrial sulfane sulfur (MSS) remain largely uncharacterized as compared with their cytosolic counterparts, cytosolic sulfane sulfur (CSS). To investigate this, we designed a novel artificial substrate for mitochondrial 3-mercaptopyruvate sulfurtransferase (3-MST), a key enzyme involved in MSS biosynthesis. Using cells expressing a mitochondrion-localized persulfide biosensor, we demonstrate this tool's ability to selectively enhance MSS. While H2S was previously known to suppress human immunodeficiency virus (HIV-1), we found that MSS profoundly affected the HIV-1 life cycle, mediating viral reactivation from latency. Additionally, we provide evidence for the role of the host's mitochondrial redox state, membrane potential, apoptosis, and respiration rates in managing HIV-1 latency and reactivation. Together, dynamic fluctuations in the MSS pool have a significant and possibly conflicting effect on HIV-1 viral latency. The precision tools developed herein allow for orthogonal generation of persulfide within both mitochondria and the cytosol and will be useful in interrogating disease biology.

Advancements in increasing efficiency of hydrogen sulfide in therapeutics: Strategies for targeted delivery as prodrugs

Hydrogen sulfide (H2S) has emerged as a potent therapeutic agent with diverse physiological functions, including vasodilation, anti-inflammation, and cytoprotection. However, its clinical application is limited due to its volatility and potential toxicity at high concentrations. To address these challenges, researchers have developed various H2S prodrugs that release H2S in a controlled and targeted manner. The review underscores the importance of targeting and delivery strategies in maximizing the therapeutic potential of H2S, a gasotransmitter with diverse physiological functions and therapeutic effects. By summarizing recent advancements, the review provides valuable insights for researchers and clinicians interested in harnessing the therapeutic benefits of H2S while minimizing off-target effects and toxicity. The integration of novel targeting and delivery approaches not only enhances the efficacy of H2S-based therapeutics but also expands the scope of potential applications, offering promising avenues for the development of new treatments for a variety of diseases and disorders.

Discovery of SIRT1-Activating Hydrogen Sulfide Donating Derivatives for Efficient Resistant of Myocardial Ischemic Injury

Activating SIRT1 or promoting SIRT1 expression are both protective against myocardial ischemia. Combining these approaches would be an effective strategy for treating ischemic heart disease. Herein, we identified lead compounds with SIRT1 activation activity through screening the natural product library, and five series of H2S donating derivatives were designed and synthesized. Among them, compound 17 exerted an effective cardioprotective effect in vitro and in vivo. The addition of H2S scavenger attenuated the protective activity, emphasizing the critical involvement of H2S in the myocardial ischemia process. Interestingly, 17 exhibited stronger direct SIRT1 activative ability and induced higher SIRT1 expression capability compared to the lead. Furthermore, 17 attenuates oxidative stress-induced cardiomyocytes apoptosis by activating the SIRT1-PGC1α signaling pathway. Our study validated the promising potential of activating SIRT1 and promoting SIRT1 expression through H2S to improve cardiomyocytes function, providing novel insights into the protective mechanisms during the progression of ischemic heart disease.

Neuroprotective signaling by hydrogen sulfide and its dysregulation in Alzheimer's disease

The ancient messenger molecule hydrogen sulfide (H2S) modulates myriad signaling cascades and has been conserved across evolutionary boundaries. Although traditionally known as an environmental toxin, H2S is also synthesized endogenously to exert modulatory and homeostatic effects in a broad array of physiologic functions. Notably, H2S levels are tightly physiologically regulated, as both its excess and paucity can be toxic. Accumulating evidence has revealed pivotal roles for H2S in neuroprotection and normal cognitive function, and H2S homeostasis is dysregulated in neurodegenerative conditions. Here, we review the normal neuroprotective roles of H2S that go awry in Alzheimer's disease, the most common form of neurodegenerative disease.

Understanding coenzyme Q

Coenzyme Q (CoQ), also known as ubiquinone, comprises a benzoquinone head group and a long isoprenoid side chain. It is thus extremely hydrophobic and resides in membranes. It is best known for its complex function as an electron transporter in the mitochondrial electron transport chain (ETC) but is also required for several other crucial cellular processes. In fact, CoQ appears to be central to the entire redox balance of the cell. Remarkably, its structure and therefore its properties have not changed from bacteria to vertebrates. In metazoans, it is synthesized in all cells and is found in most, and maybe all, biological membranes. CoQ is also known as a nutritional supplement, mostly because of its involvement with antioxidant defenses. However, whether there is any health benefit from oral consumption of CoQ is not well established. Here we review the function of CoQ as a redox-active molecule in the ETC and other enzymatic systems, its role as a prooxidant in reactive oxygen species generation, and its separate involvement in antioxidant mechanisms. We also review CoQ biosynthesis, which is particularly complex because of its extreme hydrophobicity, as well as the biological consequences of primary and secondary CoQ deficiency, including in human patients. Primary CoQ deficiency is a rare inborn condition due to mutation in CoQ biosynthetic genes. Secondary CoQ deficiency is much more common, as it accompanies a variety of pathological conditions, including mitochondrial disorders as well as aging. In this context, we discuss the importance, but also the great difficulty, of alleviating CoQ deficiency by CoQ supplementation.

Why Symptoms Linger in Quiescent Crohn's Disease: Investigating the Impact of Sulfidogenic Microbes and Sulfur Metabolic Pathways

Introduction

Even in the absence of inflammation, persistent symptoms in patients with Crohn's disease (CD) are prevalent and worsen quality of life. We previously demonstrated enrichment in sulfidogenic microbes in quiescent Crohn's disease patients with ( qCD+S ) vs. without persistent GI symptoms ( qCD-S ). Thus, we hypothesized that sulfur metabolic pathways would be enriched in stool while differentially abundant microbes would be associated with important sulfur-metabolic pathways in qCD+S.

Methods

We performed a multi-center observational study nested within SPARC IBD. Quiescent inflammation was defined by fecal calprotectin level <150 mcg/g. Persistent symptoms were defined by CD-PRO2. Active CD ( aCD ) and non-IBD diarrhea-predominant irritable bowel syndrome ( IBS-D ) were included as controls.

Results

Thirty-nine patients with qCD+S, 274 qCD-S, 21 aCD, and 40 IBS-D underwent paired shotgun metagenomic sequencing and untargeted metabolomic profiling. The fecal metabolome in qCD+S was significantly different relative to qCD-S and IBS-D but not aCD. Patients with qCD+S were enriched in sulfur-containing amino acid pathways, including cysteine and methionine, as well as serine, glycine, and threonine. Glutathione and nicotinate/nicotinamide pathways were also enriched in qCD+S relative to qCD-S, suggestive of mitochondrial dysfunction, a downstream target of H 2 S signaling. Multi-omic integration demonstrated that enriched microbes in qCD+S were associated with important sulfur-metabolic pathways. Bacterial sulfur-metabolic genes, including CTH , isfD , sarD , and asrC , were dysregulated in qCD+S. Finally, sulfur metabolites with and without sulfidogenic microbes showed good accuracy in predicting presence of qCD+S.

Discussion

Microbial-derived sulfur pathways and downstream mitochondrial function are perturbed in qCD+S, which implicate H 2 S signaling in the pathogenesis of this condition. Future studies will determine whether targeting H 2 S pathways results in improved quality of life in qCD+S.

Key Messages

What is Already Known Even in the absence of inflammation, persistent gastrointestinal symptoms are common in Crohn's disease.The microbiome is altered in quiescent Crohn's disease patients with persistent symptoms, but the functional significance of these changes is unknown. What is New Here Sulfur metabolites and sulfur metabolic pathways were enriched in stool in quiescent Crohn's disease patients with persistent symptoms.Multi-omic integration showed enriched microbes were associated with important sulfur metabolic pathways in quiescent Crohn's disease patients with persistent symptoms. How Can This Study Help Patient Care Strategies to decrease sulfidogenic microbes and associated sulfur metabolic pathways could represent a novel strategy to improve quality of life in quiescent Crohn's disease with persistent GI symptoms.

Nanocoated bacteria with H2S generation-triggered self-amplified photothermal and photodynamic effect for breast cancer therapy

Phototherapy utilizing bacterial carriers has demonstrated efficacy in anti-tumor therapy, while the poor delivery of phototherapeutic agents and immunogenicity of microbial substances remain problematic. Herein, we develop a nanocoated bacterial delivery system (IF-S.T) that in situ forms the efficient photothermal agents via biomineralization and improves the intracellular oxygenation, thus triggering the self-enhanced photothermal therapy (PTT) and photodynamic therapy (PDT) on tumor. We densely coat self-assembled IF (ICG-Fe2+) nanocomplex onto the surface of LT2, weakly virulent strain of Salmonella typhimurium (S.T), by bioadaptive nanocoating techniques, masking bacterial virulence factors and reducing the potential immune adverse effects. Upon penetrating into the tumor environment, IF-S.T responds to H2O2 to trigger the removal of the IF coating, where S.T produces excess hydrogen sulfide (H2S). H2S reacts with Fe2+, yielding ferrous sulfide (FeS) for PTT, and inhibits mitochondrial respiration to enhance tumor cell oxygenation for PDT. Consequently, IF-S.T plus laser irradiation exhibits direct tumor cells killing and elicits robust antitumor immune responses, leading to the complete tumor elimination. Thus, IF-S.T represents a promising platform for effective tumor delivery of photoactive agents for improved PTT/PDT efficacy.

Modified montmorillonite armed probiotics with enhanced on-site mucus-depleted intestinal colonization and H2S scavenging for colitis treatment

Inflammatory bowel diseases (IBD) are often associated with dysregulated gut microbiota and excessive inflammatory microenvironment. Probiotic therapy combined with inflammation management is a promising approach to alleviate IBD, but the efficacy is hindered by the inferior colonization of probiotics in mucus-depleted inflammatory bowel segments. Here, we present modified montmorillonite armed probiotic Escherichia coli Nissle 1917 (MMT-Fe@EcN) with enhanced intestinal colonization and hydrogen sulfide (H2S) scavenging for synergistic alleviation of IBD. The montmorillonite layer that can protect EcN against environmental assaults in oral delivery and improve on-site colonization of EcN in the mucus-depleted intestinal segment due to its strong adhesive capability and electronegativity, with a 22.6-fold increase in colonization efficiency compared to EcN. Meanwhile, MMT-Fe@EcN can manage inflammation by scavenging H2S, which allows for enhancing probiotic viability and colonization for restoring the gut microbiota. As a result, MMT-Fe@EcN exhibits extraordinary therapeutic effects in the dextran sulfate sodium-induced mouse colitis models, including alleviating intestinal inflammation and restoring disrupted intestinal barrier function, and gut microbiota. These findings provide a promising strategy for clinical IBD treatment and potentially other mucus-depletion-related diseases.

Hydrogen sulfide maintains mitochondrial homeostasis and regulates ganoderic acids biosynthesis by SQR under heat stress in Ganoderma lucidum

Hydrogen sulfide (H2S) has recently been recognized as an important gaseous transmitter with multiple physiological effects in various species. Previous studies have shown that H2S alleviated heat-induced ganoderic acids (GAs) biosynthesis, an important quality index of Ganoderma lucidum. However, a comprehensive understanding of the physiological effects and molecular mechanisms of H2S in G. lucidum remains unexplored. In this study, we found that heat treatment reduced the mitochondrial membrane potential (MMP) and mitochondrial DNA copy number (mtDNAcn) in G. lucidum. Increasing the intracellular H2S concentration through pharmacological and genetic means increased the MMP level, mtDNAcn, oxygen consumption rate level and ATP content under heat treatment, suggesting a role for H2S in mitigating heat-caused mitochondrial damage in G. lucidum. Further results indicated that H2S activates sulfide-quinone oxidoreductase (SQR) and complex III (Com III), thereby maintaining mitochondrial homeostasis under heat stress in G. lucidum. Moreover, SQR also mediated the negative regulation of H2S to GAs biosynthesis under heat stress. Furthermore, SQR might be persulfidated under heat stress in G. lucidum. Thus, our study reveals a novel physiological function and molecular mechanism of H2S signalling under heat stress in G. lucidum with broad implications for research on the environmental response of microorganisms.

Responsive β-Diketonate-europium(III) Complex-Based Probe for Time-Gated Luminescence Detection and Imaging of Hydrogen Sulfide In Vitro and In Vivo

As a crucial biological gasotransmitter, hydrogen sulfide (H2S) plays important roles in many pathological and physiological processes. Highly selective and sensitive detection of H2S is significant for the precise diagnosis and evaluation of diverse diseases. Nevertheless, challenges remain in view of the interference of autofluorescence in organisms and the stronger reactivity of H2S itself. Herein, we report the design and synthesis of a novel H2S-responsive β-diketonate-europium(III) complex-based probe, [Eu(DNB-Npketo)3(terpy)], for background-free time-gated luminescence (TGL) detection and imaging of H2S in autofluorescence-rich biological samples. The probe, consisting of a 2,4-dinitrobenzenesulfonyl (DNB) group coupled to a β-diketonate-europium(III) complex, shows almost no luminescence owing to the existence of intramolecular photoinduced electron transfer. The cleavage of the DNB group by a H2S-triggered reaction results in the recovery of the long-lived luminescence of the Eu3+ complex, allowing the detection of H2S in complicated biological samples to be performed in TGL mode. The probe showed a fast response, high specificity, and high sensitivity toward H2S, which enabled it to be successfully used for the quantitative TGL detection of H2S in tissue homogenates of mouse organs. Additionally, the low cytotoxicity of the probe allowed it to be further used for the TGL imaging of H2S in living cells and mice under different stimuli. All of the results suggested the potential of the probe for the investigation and diagnosis of H2S-related diseases.

Concurrent Subcellular Delivery of Hydrogen Sulfide and a Payload with Near-Infrared Light

Hydrogen sulfide (H2S) is a gaseous signaling molecule, exerting crucial regulatory functions in organelles and cellular environments. H2S exhibits high therapeutic potential and synergistic effects with other drugs, and its potency is notably enhanced through organelle-specific targeting. Yet, the navigation of light-activated H2S donors to specific organelles remains absent. Here, we report the first organelle-specific photocage that simultaneously delivers H2S and a payload with subcellular precision to mitochondria of live human cells using tissue-penetrating near-infrared light as a trigger. The fluorogenic payload enables real-time monitoring of the process, and we demonstrate the concurrent uncaging in mitochondria through a combination of fluorescence microscopy and mitochondria-specific fluorescent probes. We anticipate that these photocages will permit the precise delivery of H2S-drug combinations with exceptional spatiotemporal control, thereby driving the harnessing of known synergistic effects and the discovery of novel therapeutic strategies.

Hydrogen Sulfide can Scavenge Free Radicals to Improve Spinal Cord Injury by Inhibiting the p38MAPK/mTOR/NF-κB Signaling Pathway

Spinal cord injury (SCI) causes irreversible cell loss and neurological dysfunctions. Presently, there is no an effective clinical treatment for SCI. It can be the only intervention measure by relieving the symptoms of patients such as pain and fever. Free radical-induced damage is one of the validated mechanisms in the complex secondary injury following primary SCI. Hydrogen sulfide (H2S) as an antioxidant can effectively scavenge free radicals, protect neurons, and improve SCI by inhibiting the p38MAPK/mTOR/NF-κB signaling pathway. In this report, we analyze the pathological mechanism of SCI, the role of free radical-mediated the p38MAPK/mTOR/NF-κB signaling pathway in SCI, and the role of H2S in scavenging free radicals and improving SCI.

UW Supplementation with AP39 Improves Liver Viability Following Static Cold Storage

Static cold storage of donor livers at 4°C incompletely arrests metabolism, ultimately leading to decreases in ATP levels, oxidative stress, cell death, and organ failure. Hydrogen Sulfide (H2S) is an endogenously produced gas, previously demonstrated to reduce oxidative stress, reduce ATP depletion, and protect from ischemia and reperfusion injury. H2S is difficult to administer due to its rapid release curve, resulting in cellular death at high concentrations. AP39, a mitochondrially targeted, slow-release H2S donor, has been shown to reduce ischemia-reperfusion injury in hearts and kidneys. Thus, we investigated whether the addition of AP39 during 3-day static cold storage can improve liver graft viability. At the end of storage, livers underwent six hours of acellular normothermic machine perfusion, a model of transplantation. During simulated transplantation, livers stored with AP39 showed reduced resistance, reduced cellular damage (ALT and AST), and reduced apoptosis. Additionally, bile production and glucose, as well as energy charge were improved by the addition of AP39. These results indicate that AP39 supplementation improves liver viability during static cold storage.

Mining proteomes for zinc finger persulfidation

Hydrogen sulfide (H2S) is an endogenous gasotransmitter that signals via persulfidation. There is evidence that the cysteine residues of certain zinc finger (ZF) proteins, a common type of cysteine rich protein, are modified to persulfides by H2S. To determine how frequently ZF persulfidation occurs in cells and identify the types of ZFs that are persulfidated, persulfide specific proteomics data were evaluated. 22 datasets from 16 studies were analyzed via a meta-analysis approach. Persulfidated ZFs were identified in a range of eukaryotic species, including Homo sapiens, Mus musculus, Rattus norvegicus, Arabidopsis thaliana, and Emiliania huxley (single-celled phytoplankton). The types of ZFs identified for each species encompassed all three common ZF ligand sets (4-cysteine, 3-cysteine-1-histidine, and 2-cysteine-2-hisitidine), indicating that persulfidation of ZFs is broad. Overlap analysis between different species identified several common ZFs. GO and KEGG analysis identified pathway enrichment for ubiquitin-dependent protein catabolic process and viral carcinogenesis. These collective findings support ZF persulfidation as a wide-ranging PTM that impacts all classes of ZFs.

A multifunctional protein-based hydrogel with Au nanozyme-mediated self generation of H2S for diabetic wound healing

Diabetics usually suffer from chronic impaired wound healing due to facile infection, excessive inflammation, diabetic neuropathy, and peripheral vascular disease. Hence, the development of effective diabetic wound therapy remains a critical clinical challenge. Hydrogen sulfide (H2S) regulates inflammation, oxidative stress, and angiogenesis, suggesting a potential role in promoting diabetic wound healing. Herein, we propose a first example of fabricating an antibiotic-free antibacterial protein hydrogel with self-generation of H2S gas (H2S-Hydrogel) for diabetic wound healing by simply mixing bovine serum albumin‑gold nanoclusters (BSA-AuNCs) with Bis[tetrakis(hydroxymethyl)phosphonium] sulfate (THPS) at room temperature within a few minutes. In this process, the amino group in BAS and the aldehyde group in THPS are crossed together by Mannich reaction. At the same time, tris(hydroxymethyl) phosphorus (trivalent phosphorus) from THPS hydrolysis could reduce disulfide bonds in BSA to sulfhydryl groups, and then the sulfhydryl group generates H2S gas under the catalysis of BSA-AuNCs. THPS in H2S-Hydrogel can destroy bacterial biofilms, while H2S can inhibit oxidative stress, promote proliferation and migration of epidermal/endothelial cells, increase angiogenesis, and thus significantly increase wound closure. It would open a new perspective on the development of effective diabetic wound dressing.

First transcriptomic insight into the working muscles of racing pigeons during a competition flight

BACKGROUND

The currently known homing pigeon is a result of a sharp one-sided selection for flight characteristics focused on speed, endurance, and spatial orientation. This has led to extremely well-adapted athletic phenotypes in racing birds.

METHODS

Here, we identify genes and pathways contributing to exercise adaptation in sport pigeons by applying next-generation transcriptome sequencing of m.pectoralis muscle samples, collected before and after a 300 km competition flight.

RESULTS

The analysis of differentially expressed genes pictured the central role of pathways involved in fuel selection and muscle maintenance during flight, with a set of genes, in which variations may therefore be exploited for genetic improvement of the racing pigeon population towards specific categories of competition flights.

CONCLUSIONS

The presented results are a background to understanding the genetic processes in the muscles of birds during flight and also are the starting point of further selection of genetic markers associated with racing performance in carrier pigeons.

Redox Regulation of Mitochondrial Potassium Channels Activity

Redox reactions exert a profound influence on numerous cellular functions with mitochondria playing a central role in orchestrating these processes. This pivotal involvement arises from three primary factors: (1) the synthesis of reactive oxygen species (ROS) by mitochondria, (2) the presence of a substantial array of redox enzymes such as respiratory chain, and (3) the responsiveness of mitochondria to the cellular redox state. Within the inner mitochondrial membrane, a group of potassium channels, including ATP-regulated, large conductance calcium-activated, and voltage-regulated channels, is present. These channels play a crucial role in conditions such as cytoprotection, ischemia/reperfusion injury, and inflammation. Notably, the activity of mitochondrial potassium channels is intricately governed by redox reactions. Furthermore, the regulatory influence extends to other proteins, such as kinases, which undergo redox modifications. This review aims to offer a comprehensive exploration of the modulation of mitochondrial potassium channels through diverse redox reactions with a specific focus on the involvement of ROS.