Synergistic interplay between melatonin and hydrogen sulfide enhances cadmium-induced oxidative stress resistance in stock (Matthiola incana L.).

Ornamental crops particularly cut flowers are considered sensitive to heavy metals (HMs) induced oxidative stress condition. Melatonin (MLT) is a versatile phytohormone with the ability to mitigate abiotic stresses induced oxidative stress in plants. Similarly, signaling molecules such as hydrogen sulfide (H2S) have emerged as potential options for resolving HMs related problems in plants. The mechanisms underlying the combined application of MLT and H2S are not yet explored. Therefore, we evaluated the ability of individual and combined applications of MLT (100 µM) and H2S in the form of sodium hydrosulfide (NaHS), a donor of H2S, (1.5 mM) to alleviate cadmium (Cd) stress (50 mg L-1) in stock (Matthiola incana L.) plants by measuring various morpho-physiological and biochemical characteristics. The results depicted that Cd-stress inhibited growth, photosynthesis and induced Cd-associated oxidative stress as depicted by excessive ROS accumulation. Combined application of MLT and H2S efficiently recovered all these attributes. Furthermore, Cd stress-induced oxidative stress markers including electrolyte leakage, malondialdehyde, and hydrogen peroxide are partially reversed in Cd-stressed plants by MLT and H2S application. This might be attributed to MLT or H2S induced antioxidant plant defense activities, which effectively reduce the severity of oxidative stress indicators. Overall, MLT and H2S supplementation, favorably regulated Cd tolerance in stock; yet, the combined use had a greater effect on Cd tolerance than the independent application.

Curcumin reduces myocardial ischemia-reperfusion injury, by increasing endogenous H2S levels and further modulating m6A.

BACKGROUND: Our previous research shows that Curcumin (CUR) attenuates myocardial ischemia-reperfusion injury (MIRI) by reducing intracellular total RNA m6A levels. However, the mechanism remains unknown. METHODS: For ischemia-reperfusion (IR), H9c2 cells were cultured for 6 h in serum-free low-glycemic (1 g/L) medium and a gas environment without oxygen, and then cultured for 6 h in high-glycemic (4.5 g/L) medium supplemented with 10% FBS and a 21% oxygen environment. The effects of different concentrations of CUR (5, 10, and 20 µM) treatments on signaling molecules in conventionally cultured and IR-treated H9c2 cells were examined. RESULTS: CUR treatment significantly up-regulated the H2S levels, and the mRNA and protein expression of cystathionine γ-lyase (CSE), and down-regulated the mRNAs and proteins levels of thiosulfate sulfurtransferase (TST) and ethylmalonic encephalopathy 1 (ETHE1) in H9c2 cells conventionally cultured and subjected to IR. Exogenous H2S supply (NaHS and GYY4137) significantly reduced intracellular total RNA m6A levels, and the expression of RNA m6A "writers" METTL3 and METTL14, and increased the expression of RNA m6A "eraser" FTO in H9c2 cells conventionally cultured and subjected to IR. CSE knockdown counteracted the inhibitory effect of CUR treatment on ROS production, promotion on cell viability, and inhibition on apoptosis of H9c2 cells subjected to IR. CONCLUSION: CUR attenuates MIRI by regulating the expression of H2S level-regulating enzymes and increasing the endogenous H2S levels. Increased H2S levels could regulate the m6A-related proteins expression and intracellular total RNA m6A levels.

AP39, a novel mitochondria-targeted hydrogen sulfide donor ameliorates doxorubicin-induced cardiotoxicity by regulating the AMPK/UCP2 pathway.

Doxorubicin (DOX) is a broad-spectrum, highly effective antitumor agent; however, its cardiotoxicity has greatly limited its use. Hydrogen sulfide (H2S) is an endogenous gaseous transmitter that exerts cardioprotective effects via the regulation of oxidative stress and apoptosis and maintenance of mitochondrial function, among other mechanisms. AP39 is a novel mitochondria-targeted H2S donor that, at appropriate concentrations, attenuates intracellular oxidative stress damage, maintains mitochondrial function, and ameliorates cardiomyocyte injury. In this study, DOX-induced cardiotoxicity models were established using H9c2 cells and Sprague-Dawley rats to evaluate the protective effect of AP39 and its mechanisms of action. Both in vivo and in vitro experiments showed that DOX induces oxidative stress injury, apoptosis, and mitochondrial damage in cardiomyocytes and decreases the expression of p-AMPK/AMPK and UCP2. All DOX-induced changes were attenuated by AP39 treatment. Furthermore, the protective effect of AP39 was significantly attenuated by the inhibition of AMPK and UCP2. The results suggest that AP39 ameliorates DOX-induced cardiotoxicity by regulating the expression of AMPK/UCP2.

H2S-driven chemotherapy and mild photothermal therapy induced mitochondrial reprogramming to promote cuproptosis.

The elevated level of hydrogen sulfide (H2S) in colon cancer hinders complete cure with a single therapy. However, excessive H2S also offers a treatment target. A multifunctional cascade bioreactor based on the H2S-responsive mesoporous Cu2Cl(OH)3-loaded hypoxic prodrug tirapazamine (TPZ), in which the outer layer was coated with hyaluronic acid (HA) to form TPZ@Cu2Cl(OH)3-HA (TCuH) nanoparticles (NPs), demonstrated a synergistic antitumor effect through combining the H2S-driven cuproptosis and mild photothermal therapy. The HA coating endowed the NPs with targeting delivery to enhance drug accumulation in the tumor tissue. The presence of both the high level of H2S and the near-infrared II (NIR II) irradiation achieved the in situ generation of photothermic agent copper sulfide (Cu9S8) from the TCuH, followed with the release of TPZ. The depletion of H2S stimulated consumption of oxygen, resulting in hypoxic state and mitochondrial reprogramming. The hypoxic state activated prodrug TPZ to activated TPZ (TPZ-ed) for chemotherapy in turn. Furthermore, the exacerbated hypoxia inhibited the synthesis of adenosine triphosphate, decreasing expression of heat shock proteins and subsequently improving the photothermal therapy. The enriched Cu2+ induced not only cuproptosis by promoting lipoacylated dihydrolipoamide S-acetyltransferase (DLAT) heteromerization but also performed chemodynamic therapy though catalyzing H2O2 to produce highly toxic hydroxyl radicals ·OH. Therefore, the nanoparticles TCuH offer a versatile platform to exert copper-related synergistic antitumor therapy.

H2S preconditioning induces long-lived perturbations in O2 metabolism.

Hydrogen sulfide exposure in moderate doses can induce profound but reversible hypometabolism in mammals. At a cellular level, H2S inhibits the electron transport chain (ETC), augments aerobic glycolysis, and glutamine-dependent carbon utilization via reductive carboxylation; however, the durability of these changes is unknown. We report that despite its volatility, H2S preconditioning increases P50(O2), the O2 pressure for half-maximal cellular respiration, and has pleiotropic effects on oxidative metabolism that persist up to 24 to 48 h later. Notably, cyanide, another complex IV inhibitor, does not induce this type of metabolic memory. Sulfide-mediated prolonged fractional inhibition of complex IV by H2S is modulated by sulfide quinone oxidoreductase, which commits sulfide to oxidative catabolism. Since induced hypometabolism can be beneficial in disease settings that involve insufficient or interrupted blood flow, our study has important implications for attenuating reperfusion-induced ischemic injury and/or prolonging the shelf life of biologics like platelets.

Hydrogen sulfide improves endothelial barrier function by modulating the ubiquitination degradation of KLF4 through TRAF7 S-sulfhydration in diabetic aorta.

Anomalous vascular endothelium significantly contributes to various cardiovascular diseases. VE-cadherin plays a vital role in governing the endothelial barrier. Krüppel-like factor 4(KLF4), as a transcription factor, which binds the VE-cadherin promoter and enhances its transcription. Tumor necrosis factor receptor-associated factor 7 (TRAF7) is an E3 ubiquitin ligase that has been shown to modulate the degradation of KLF4. H2S can covalently modify cysteine residues on proteins through S-sulfhydration, thereby influencing the structure and functionality of the target protein. However, the role of S-sulfhydration on endothelial barrier integrity remains to be comprehensively elucidated. This study aims to investigate whether protein S-sulfhydration in the endothelium regulates endothelial integrity and its underlying mechanism. In this study, we observed that protein S-sulfhydration was reduced in the endothelium during diabetes and TRAF7 was the main target. Overexpression of TRAF7-Cys327 mutant could mitigate the endothelial barrier damage by weakening TRAF7 interaction with KLF4 and reducing ubiquitination degradation of KLF4. In conclusion, our research demonstrates that H2S plays a pivotal role in regulating S-sulfhydration of TRAF7 at Cys327. This regulation effectively inhibits the ubiquitin-mediated degradation of KLF4, resulting in an upregulation of VE-cadherin levels. This molecular mechanism contributes to the prevention of endothelial barrier damage.

Aqueous-phase dual-functional chiral perovskites for hydrogen sulfide (H2S) detection and antibacterial applications in Escherichia coli.

Perovskite nanocrystals (PNCs) have attracted extensive attention for their potential applications in biology. However, only a handful of PNCs have been scrutinized in the biological domain due to issues such as instability, poor dispersion, and size inhomogeneity in polar solvents. The development of dual-functional perovskite nanomaterials with hydrogen sulfide (H2S) sensing and antibacterial capabilities is particularly intriguing. In this study, we prepared chiral quasi-two-dimensional (quasi-2D) perovskite nanomaterials, Bio(S-PEA)2CsPb2Br7 and Bio(R-PEA)2CsPb2Br7, that were uniformly dispersed in aqueous media. The effective encapsulation of methoxypolyethylene glycol amine (mPEG-NH2) improved water stability and uniformity of particle size. Circular dichroism (CD) signals were created by the successful insertion of chiral cations. These perovskites as probes showed a rapid and sensitive fluorescence quenching response to H2S, and the effect of imaging detection was observed at the Escherichia coli (E. coli) level. As antibacterial agents, their pronounced positive charge properties facilitated membrane lysis and subsequent E. coli death, indicating a significant antibacterial effect. This work has preliminary explored the application of chiral perovskites in biology and provides insight into the development of bifunctional perovskite nanomaterials for biological applications.

Effect of hydrogen sulfide on cabbage photosynthesis under black rot stress.

Hydrogen sulfide (H2S), as a potential gaseous signaling molecule, is involved in mediating biotic and abiotic stress in plants. Currently, there are no studies investigating the mechanism by which H2S improves photosynthesis under black rot (BR) stress caused by Xanthomonas campestris pv. Campestris (Xcc). In this study, we investigated the effect of exogenous H2S on Xcc induced photosynthetic impairment in cabbage seedlings. BR has an inhibitory effect on the photosynthetic ability of cabbage seedlings. Xcc infection can significantly reduce the chlorophyll content, photosynthetic characteristics, chlorophyll fluorescence, Calvin cycle related enzyme activity and gene expression in cabbage leaves. The use of H2S can alleviate this inhibitory effect, reduce chlorophyll decomposition, improve gas exchange, enhance the activity of Calvin cycle related enzymes, and increase the expression of related genes. Transcriptome analysis showed that all differential genes related to photosynthesis were up regulated under H2S treatment compared to normal inoculation. Therefore, spraying exogenous H2S can improve the photosynthetic capacity of cabbage seedlings, reduce Xcc induced photoinhibition, and improve plant resistance.

Neuromodulator hydrogen sulfide attenuates sickness behavior induced by lipopolysaccharide.

Sickness behavior reflects a state of altered physiology and central nervous system function that occurs during systemic infection or inflammation, serving as an adaptive response to illness. This study aims to elucidate the role of hydrogen sulfide (H2S) in regulating sickness behavior and neuroinflammatory responses in a rat model of systemic inflammation. Adult male Wistar rats were treated with lipopolysaccharide (LPS) to induce sickness behavior. Intracerebroventricular (i.c.v.) pretreatments included aminooxyacetic acid (AOAA), an inhibitor of H2S synthesis, and sodium sulfide (NaHS), an H2S donor. Behavioral assays were conducted, along with the assessment of astrocyte activation, as indicated by GFAP expression in the hypothalamus. Pretreatment with NaHS mitigated LPS-induced behavioral changes, including hypophagia, social and exploratory deficits, without affecting peripheral cytokine levels, indicating a central modulatory effect. AOAA, conversely, accentuated certain behavioral responses, suggesting a complex role of endogenous H2S in sickness behavior. These findings were reinforced by a lack of effect on plasma interleukin levels but significant reduction in GFAP expression. Our findings support the central role of H2S in modulating neuroinflammation and sickness behavior, highlighting the therapeutic potential of targeting H2S signaling in neuroinflammatory conditions.

Glycosidase-activated H2S donorsto enhance chemotherapy efficacy.

Hydrogen sulfide (H2S) plays a critical role in cancer biology. Herein, we developed a series of glycosidase-triggered hydrogen sulfide (H2S) donors by connecting sugar moieties (including glucose, galactose and mannose) to COS donors via a self-immolative spacer. In the presence of corresponding glycosidases, H2S was gradually released from these donors in PBS buffer with releasing efficiencies from 36 to 67 %. H2S release was also detected by H2S probe WSP-1 after treatment HepG2 cells with Man1. Cytotoxicities of these glycosylated H2S donors were evaluated against HepG2 by MTT assay. Among them, Man1 and Man2 exhibited an obvious reduction of cell viability in HepG2 cells, with cell viability as 37.6 % for 80 µM of Man. Consistently, significant apoptosis was observed in HepG2 cells after treatment with Man1 and Man2. Finally, We evaluated the potential of Man1 for combination therapy with doxorubicin. A synergistic effect was observed between Man1 and Doxorubicin in HepG2 and Hela cells. All these results indicated glycosidase-activated H2S donorshave promising potential for cancer therapy.

Hydrogen sulfide protects cardiomyocytes from doxorubicin-induced ferroptosis through the SLC7A11/GSH/GPx4 pathway by Keap1 S-sulfhydration and Nrf2 activation.

Recent studies have demonstrated that ferroptosis, a novel form of nonapoptotic regulated cell death plays an important role in doxorubicin (DOX)-induced cardiotoxicity (DoIC). Hydrogen sulfide (H2S) is emerging as the third important gaseous mediator in cardiovascular system. However, whether H2S has an effect on DOX-induced ferroptosis remains unknown. Here, we found that DOX not only triggered cardiomyocyte ferroptosis but also significantly inhibited the synthesis of endogenous H2S in the murine model of chronic DoIC. Application of NaHS, an H2S donor obviously activated the SLC7A11/GSH/GPx4 antioxidant pathway and thus alleviated DOX-induced ferroptosis and cardiac injury in mice. In contrast, cardiac-specific knockout of cystathionine γ-lyase gene (Cse) in mice (Csef/f/Cre+) to abolish the cardiac synthesis of endogenous H2S evidently exacerbated DOX-induced ferroptosis and cardiac dysfunction. A further suppression of SLC7A11/GSH/GPx4 pathway was obtained in Csef/f/Cre+ mice with DoIC, as compared to Csef/f/Cre- mice with DoIC. The aggravation caused by cardiac-specific Cse deficiency was remarkably rescued by exogenous supplementation of NaHS. Moreover, in DOX-stimulated H9c2 cardiomyocytes, pretreatment with NaHS dose-dependently enhanced the activity of SLC7A11/GSH/GPx4 pathway and subsequently mitigated ferroptosis and mitochondrial impairment. On the contrary, transfection with Cse siRNA in DOX-stimulated H9c2 cardiomyocytes markedly inhibited SLC7A11/GSH/GPx4 pathway, thus leading to aggravated ferroptosis and more damage to mitochondrial structure and function. In addition, the protective effect of NaHS on DOX-induced ferroptosis was closely related to the S-sulfhydrated Keap1, which in turn promoted nuclear translocation of Nrf2 and the transcription of SLC7A11 and GPx4. In conclusion, our findings suggest that H2S may exert protective effect on DoIC by inhibiting DOX-induced ferroptosis via Keap1/Nrf2-dependent SLC7A11/GSH/GPx4 antioxidant pathway.

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

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

H2S serves as the immunoregulatory essence of apoptotic cell death.

Apoptosis supports tissue homeostasis and prevents immune disorders by removing damaged and functionally aberrant cells. Here, Ou et al. utilized genetic, pharmacological, and proteomic approaches focused on sulfur amino acid catabolism to discover that hydrogen sulfide (H2S) release during apoptosis suppresses Th17 cell differentiation, thus providing therapeutic targets for autoimmune diseases.

Exogenous hydrogen sulfide ameliorates diabetes-associated cognitive dysfunction by regulating the nrf-2/HO-1 axis and the NLRP3 inflammasome pathway in diabetic rats.

Diabetes-associated cognitive dysfunction (DACD) is a complication of diabetes mellitus that leads to an increased risk of cognitive impairment and dementia. However, the molecular mechanism underlying DACD has not been elucidated, and a promising therapy for this disease remains to be established. Hydrogen sulfide (H2S), a significant antioxidative and anti-inflammatory gasotransmitter, has emerged as a neuroprotective agent. In this study, we investigated the protective effects of H2S on DACD in a streptozotocin (STZ)-induced diabetic rat model. We applied the Morris water maze to evaluate spatial learning and memory abilities. We used Western blotting and immunohistochemical staining to investigate the expression of the Nrf-2/HO-1 axis and the NLRP3 inflammasome. After NaHS (H2S donor) administration, diabetic rats exhibited improved spatial learning and memory retrieval abilities in the Morris water maze. In STZ-induced diabetic rats, the protein expression levels of the Nrf-2/HO-1 axis, the NLRP3 inflammasome and subsequent inflammatory cytokines in the hippocampal region were elevated compared to those in control rats. Exogenous H2S triggered Nrf-2/HO-1 antioxidant activity and inhibited NLRP3 inflammasome activation and proinflammatory cytokine expression. These findings suggested that exogenous H2S has neuroprotective effects by modulating the Nrf-2/HO-1 axis and the NLRP3 inflammasome pathway, which were found to be associated with DACD. H2S treatment may be a promising therapeutic strategy for preventing the progression of tissue damage caused by DACD.

Hydrogen sulfide induces Ca2+ influx in the principal cells of rat cortical collecting ducts.

Hydrogen sulfide (H2S) acts as a gas-signaling agent in various tissues. Although it has been reported that endogenous enzymes that generate H2S are expressed abundantly in the kidney, few reports examine cellular responses to H2S in renal tubular epithelial cells. In this study, we investigated the effects of NaHS, an H2S donor, and l-cysteine, a substrate for H2S production, on the principal cells of rat cortical collecting ducts (CCDs). NaHS increased the intracellular Ca2+ concentration ([Ca2+]i) in the principal cells. The removal of extracellular Ca2+ largely attenuated the [Ca2+]i response. The TRPV4 channel blocker significantly inhibited the effect of NaHS. Extracellular administration of l-cysteine also elicited a rise in [Ca2+]i. Prior treatment of CCDs with AOAA, an inhibitor of H2S production enzyme, l-cysteine-induced [Ca2+]i response was significantly reduced. These results suggest that not only exogenous H2S but also endogenously produced H2S triggers the extracellular influx pathway of Ca2+ in the principal cells of rat CCDs.

Gasotransmitters do not prevent changes in transepithelial ion transport induced by hypoxia followed by reoxygenation.

OBJECTIVES: How gaseous signalling molecules affect ion transport processes contributing to the physiological functions of the gastrointestinal tract under hypoxic conditions still needs to be clarified. The objective of the present study was to characterize the impact of gaseous signalling molecules on parameters of colonic ion transport during a hypoxia/reoxygenation cycle and the remaining secretory capacity of the epithelium after such a cycle. METHODS: Short-circuit current (Isc) and tissue conductance (Gt) recordings in Ussing chamber experiments were performed on rat colon samples using CORM-2 (putative CO donor; 35 and 350 µM), sodium nitroprusside (NO donor; 100 µM), NaHS (fast H2S donor; 10 - 1,000 µM), GYY 4137 (slow H2S donor; 50 µM) and Angeli's salt (HNO donor; 100 µM) as donors for gasotransmitters. Inhibition of endogenous synthesis of H2S was operated by inhibitors of cystathionin-γ-lyase, i.e. dl-propargylglycine (1 mM) or ß-cyano-l-alanine (5 mM), and the inhibitor of cystathionine-ß-synthase, amino-oxyacetate (5 mM). RESULTS: The fast gasotransmitter donors NaHS, sodium nitroprusside and Angeli's salt, administered 5 min before the onset of hypoxia, induced an increase in Isc. The response to the subsequently applied hypoxia was characterized by a decrease in Isc, which tended to be reduced only in the presence of the lowest concentration of NaHS (10 µM) tested. Reoxygenation resulted in a slow increase in Isc, which was unaffected by all donors or inhibitors tested. The stable acetylcholine derivative carbachol (50 µM) was administered at the end of each hypoxia/reoxygenation cycle to test the secretory capacity of the epithelium. Pretreatment of the tissue with the putative CO donor CORM-2 suppressed the secretory response induced by carbachol. The same was observed when cystathionin-γ-lyase and cystathionin-γ-synthase were inhibited simultaneously. Under both conditions, Gt drastically increased suggesting an impaired tissue integrity. CONCLUSIONS: The present results demonstrate that none of the exogenous gasotransmitter releasing drugs significantly ameliorated the changes in epithelial ion transport during the hypoxia/reoxygenation cycle ex vivo. In contrast, the putative CO donor CORM-2 exerted a toxic effect on the epithelium. The endogenous production of H2S, however, seems to have a protective effect on the mucosal integrity and the epithelial transport functions, which - when inhibited - leads to a loss of the secretory ability of the mucosa. This observation together with the trend for improvement observed with a low concentration of the H2S donor NaHS suggests a moderate protective role of low concentrations of H2S under hypoxic conditions.

A slow-releasing donor of hydrogen sulfide inhibits neuronal cell death via anti-PANoptosis in rats with spinal cord ischemia‒reperfusion injury.

BACKGROUND: Spinal cord ischemia‒reperfusion injury (SCIRI) can lead to paraplegia, which leads to permanent motor function loss. It is a disastrous complication of surgery and causes tremendous socioeconomic burden. However, effective treatments for SCIRI are still lacking. PANoptosis consists of three kinds of programmed cell death, pyroptosis, apoptosis, and necroptosis, and may contribute to ischemia‒reperfusion-induced neuron death. Previous studies have demonstrated that hydrogen sulfide (H2S) exerts a neuroprotective effect in many neurodegenerative diseases. However, whether H2S is anti-PANoptosis and neuroprotective in the progression of acute SCIRI remains unclear. Thus, in this study we aimed to explore the role of H2S in SCIRI and its underlying mechanisms. METHODS: Measurements of lower limb function, neuronal activity, microglia/macrophage function histopathological examinations, and biochemical levels were performed to examine the efficacy of H2S and to further demonstrate the mechanism and treatment of SCIRI. RESULTS: The results showed that GYY4137 (a slow-releasing H2S donor) treatment attenuated the loss of Nissl bodies after SCIRI and improved the BBB score. Additionally, the number of TUNEL-positive and cleaved caspase-3-positive cells was decreased, and the upregulation of expression of cleaved caspase-8, cleaved caspase-3, Bax, and Bad and downregulation of Bcl-2 expression were reversed after GYY4137 administration. Meanwhile, both the expression and activation of p-MLKL, p-RIP1, and p-RIP3, along with the number of PI-positive and RIP3-positive neurons, were decreased in GYY4137-treated rats. Furthermore, GYY4137 administration reduced the expression of NLRP3, cleaved caspase-1 and cleaved GSDMD, decreased the colocalization NeuN/NLRP3 and Iba1/interleukin-1ß-expressing cells, and inhibited proinflammatory factors and microglia/macrophage polarization. CONCLUSIONS: H2S ameliorated spinal cord neuron loss, prevented motor dysfunction after SCIRI, and exerted a neuroprotective effect via the inhibition of PANoptosis and overactivated microglia-mediated neuroinflammation in SCIRI.

AChE activity self-breathing control mechanisms regulated by H2Sn and GSH: Persulfidation and glutathionylation on sulfhydryl after disulfide bonds cleavage.

Hydrogen sulfide (H2S), or dihydrogen sulfane (H2Sn), acts as a signal molecule through the beneficial mechanism of persulfidation, known as the post-translational transformation of cysteine residues to persulfides. We previously reported that Glutathione (GSH) could regulate enzyme activity through S-desulfurization or glutathionylation of residues to generate protein-SG or protein-SSG, releasing H2S. However, little is known about the mechanisms by which H2Sn and GSH affect the disulfide bonds. In this study, we provide direct evidences that H2Sn and GSH modify the sulfhydryl group on Cys272, which forms disulfide bonds in acetylcholinesterase (AChE), to generate Cys-SSH and Cys-SSG, respectively. Glutathionylation of disulfide is a two-step reaction based on nucleophilic substitution, in which the first CS bond is broken, then the SS bond is broken to release H2S. H2Sn and GSH controlled self-breathing motion in enzyme catalysis by disconnecting specific disulfide bonds and modifying cysteine residues, thereby regulating AChE activity. Here, we elucidated H2Sn and GSH mechanisms on disulfide in the AChE system and proposed a self-breathing control theory induced by H2Sn and GSH. These theoretical findings shed light on the biological functions of H2Sn and GSH on sulfhydryl and disulfide bonds and enrich the theory of enzyme activity regulation.

Cardioprotective Effects of Hydrogen Sulfide and Its Potential Therapeutic Implications in the Amelioration of Duchenne Muscular Dystrophy Cardiomyopathy.

Hydrogen sulfide (H2S) belongs to the family of gasotransmitters and can modulate a myriad of biological signaling pathways. Among others, its cardioprotective effects, through antioxidant, anti-inflammatory, anti-fibrotic, and proangiogenic activities, are well-documented in experimental studies. Cardiorespiratory failure, predominantly cardiomyopathy, is a life-threatening complication that is the number one cause of death in patients with Duchenne muscular dystrophy (DMD). Although recent data suggest the role of H2S in ameliorating muscle wasting in murine and Caenorhabditis elegans models of DMD, possible cardioprotective effects have not yet been addressed. In this review, we summarize the current understanding of the role of H2S in animal models of cardiac dysfunctions and cardiac cells. We highlight that DMD may be amenable to H2S supplementation, and we suggest H2S as a possible factor regulating DMD-associated cardiomyopathy.

Hydrogels for Gasotransmitter Delivery: Nitric Oxide, Carbon Monoxide, and Hydrogen Sulfide.

Gasotransmitters, gaseous signaling molecules including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2 S), maintain myriad physiological processes. Low levels of gasotransmitters are often associated with specific problems or diseases, so NO, CO, and H2 S hold potential in treating bacterial infections, chronic wounds, myocardial infarction, ischemia, and various other diseases. However, their clinical applications as therapeutic agents are limited due to their gaseous nature, short half-life, and broad physiological roles. One route toward the greater application of gasotransmitters in medicine is through localized delivery. Hydrogels are attractive biomedical materials for the controlled release of embedded therapeutics as they are typically biocompatible, possess high water content, have tunable mechanical properties, and are injectable in certain cases. Hydrogel-based gasotransmitter delivery systems began with NO, and hydrogels for CO and H2 S have appeared more recently. In this review, the biological importance of gasotransmitters is highlighted, and the fabrication of hydrogel materials is discussed, distinguishing between methods used to physically encapsulate small molecule gasotransmitter donor compounds or chemically tether them to a hydrogel scaffold. The release behavior and potential therapeutic applications of gasotransmitter-releasing hydrogels are also detailed. Finally, the authors envision the future of this field and describe challenges moving forward.