Hydrogen Sulfide Donor Research Articles

The Protective Action of Hsp70 and Hydrogen Sulfide Donors in THP-1 Macrophages in the Lipopolysaccharide-Induced Inflammatory Response by Modulating Endocytosis

Hsp70 and hydrogen sulfide donors reduce inflammatory processes in human and animal cells. The biological action mediated by Hsp70 and H2S donors (GYY4137 and sodium thiosulfate) depends on their protection kinetics from cell activation by lipopolysaccharides. However, the molecular mechanisms of action of Hsp70 and H2S are not well understood. We studied the effect of human recombinant Hsp70 and H2S donors on the formation of reactive oxygen species and tumor necrosis factor-alpha induced in human cells (THP-1) by lipopolysaccharides. Transcriptomic changes occurring in these cells after LPS administration in combination with GYY4137 pretreatment were investigated. The results we obtained showed that Hsp70 and hydrogen sulfide donors reduce inflammatory processes in cells activated by the action of LPS. Hsp70 and H2S donors differed in the kinetics of the protective action, while hydrogen sulfide donors turned out to be more effective. The role of endocytosis in the mechanisms of protection of cells by H2S and Hsp70 donors from the action of LPS was studied. It has been found that GYY4137 pretreatment of LPS-exposed cells reduces the LPS-induced induction of various pro-inflammatory genes and affects the expression of genes of various intracellular signaling pathways.

S-Propargyl-Cysteine Ameliorates Peripheral Nerve Injury through Microvascular Reconstruction

Microvascular reconstruction is essential for peripheral nerve repair. S-Propargyl-cysteine (SPRC), the endogenous hydrogen sulfide (H2S) donor, has been reported to promote angiogenesis. The aim of this study is to utilize the pro-angiogenic ability of SPRC to support peripheral nerve repair and to explore the potential mechanisms. The effects and mechanisms of SPRC on angiogenesis and peripheral nerve repair were examined under hypoxic condition by establishing a sciatic nerve crushed injury model in mice and rats, and a hypoxia model in human umbilical vascular endothelial cells (HUVECs) in vitro. We found that SPRC accelerated the function recovery of the injured sciatic nerve and alleviated atrophy of the gastrocnemius muscle in mice. It facilitated the viability of Schwann cells (SCs), the outgrowth and myelination of regenerated axons, and angiogenesis in rats. It enhanced the viability, proliferation, adhesion, migration, and tube formation of HUVECs under hypoxic condition. SPRC activated sirtuin1 (SIRT1) expression by promoting the production of endogenous H2S, and SIRT1 negatively regulated Notch signaling in endothelial cells (ECs), thereby promoting angiogenesis. Collectively, our study has provided important evidence that SPRC has an effective role in peripheral nerve repair through microvascular reconstruction, which could be a potentially effective medical therapy for peripheral nerve injury.

Reduced hydrogen sulfide production contributes to adrenal insufficiency induced by hypoxia via modulation of NLRP3 inflammasome activation

ABSTRACTObjective: Adrenocortical responsiveness is critical for maintaining glucocorticoids production and homeostasis during stress. We sought to investigate adrenocortical responsiveness during hypoxia in mice and the mechanisms responsible for the regulation of adrenal responsiveness.Methods: (1) Adult male WT mice were randomly divided into four groups: normoxia, hypoxia (24h), hypoxia (72h), hypoxia (72h) + GYY4137(hydrogen sulfide (H2S) donor, 133mmol/kg/day); (2) WT mice were randomly divided into four groups: sham, adrenalectomy (ADX), sham+hypoxia, ADX+hypoxia; (3) Cse-/- mice were randomly divided into two groups: Cse-/-, Cse-/- +GYY4137.Results: The circulatory level of corticosteroid induced by ACTH stimulation was significantly reduced in the mice with hypoxia compared with control mice. The mortality rate induced by lipopolysaccharide (LPS) increased during hypoxia. Cystathionine-γ-lyase (CSE) expression was significantly reduced in adrenal glands during hypoxia. GYY4137 treatment significantly increased adrenal responsiveness and attenuated NLRP3 inflammasome activation in mice treated by hypoxia and Cse-/- mice. Furthermore, The sulfhydrated level of PSMA7 in adrenal gland was decreased in the mice with hypoxia and Cse-/- mice. PSMA7 was S-sulfhydrated at cysteine 70. Blockage of S-sulfhydration of PSMA7 increased NLRP3 expression in adrenocortical cells.Conclusion: Reduced H2S production mediated hypo-adrenocortical responsiveness and NLRP3 inflammasome activation via PAMA7 S-sulfhydration during hypoxia.

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

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

Updates in Kidney Transplantation From the 2022 Banff-Canadian Society of Transplantation Joint Meeting: Conference Report.

The 2022 Banff-Canadian Society of Transplantation Meeting in Banff, Alberta, brought together transplant professionals to review new developments across various aspects of solid organ transplantation (SOT) in Canada. Presentations included consensus recommendations from expert-led forums; experiences with new procedures and legislation; reports from public health data repositories; original clinical and laboratory research; and industry updates regarding novel technologies. Speakers referenced articles and reports published in peer-reviewed journals and online, and unpublished data and preliminary findings. All authors attended presentations in-person or virtually. Recordings of select presentations were available for later review. Summaries emphasize concepts indicated by speakers as new and clinically relevant. The COVID-19 pandemic disproportionately affected solid organ transplant recipients (SOTRs), who experience worse outcomes of COVID-19 infection than the general population. Vaccinations demonstrate an attenuated immunological response in SOTRs yet provide meaningful protection. Monoclonal antibodies are effective for both passive immunization and treatment of COVID-19 in SOTRs. Infection control protocols have driven the development of virtual methods for clinical research, such as using home blood draws and virtual follow-up to evaluate vaccine efficacy in SOTRs; and patient care delivery, such as employing telerehabilitation post transplant. Access to living kidney donation is limited by various disincentives experienced by potential donors, which may be overcome by more efficient evaluations including a One-Day Living Kidney Donor Assessment Clinic. The International Donation and Transplantation Legislative and Policy Forum provided a means of establishing consensus guidance for organ donation and transplantation (ODT) program policy to standardize delivery across jurisdictions. The implementation of a deemed consent model for organ and tissue donation in Nova Scotia may provide insight as to whether this model indeed improves access to organs. Canada's Indigenous population experiences unique barriers to transplantation, prompting efforts for more inclusive ODT policy-making. The Pan-Canadian ODT Data and Performance Reporting System Project has defined performance quality indicators, of which iTransplant and other point-of-care software solutions may facilitate collection; however, these endeavors ultimately require information technology infrastructure that exceeds the capabilities of the existing Canadian Organ Replacement Register and Canadian Transplant Registry. Pig-to-human xenotransplantation requires genetic modification of pigs and xenoantibody testing in recipients but may yet prove viable. Serum cell-free DNA, urine biomarkers, and genetic markers offer an alternative to routine biopsy for identifying subclinical rejection. Modified perfusion temperatures and perfusion solutions with hydrogen sulfide donor compounds may improve organ preservation. Molecular compatibility tools provide another means of improving SOTR outcomes, and the Genome Canada Transplant Consortium has been examining important considerations of their implementation. We were unable to capture all presentations and topics at the meeting due to the sizable quantity and variety. Topics ultimately excluded from this summary include those in pathology including Banff Classification updates; those unique to extra-renal SOT; as well as numerous abstract and poster presentations, allied health provider forums, and business meetings. A portion of the material was presented by speakers prior to peer-review or publication. The various conference presentations summarized in this report identify methods by which individual clinicians and provincial ODT programs may improve access, delivery, and quality of SOT care in Canada, while additionally identifying gaps in the literature that investigators are encouraged to pursue.

Hydrogen sulfide attenuates lung injury instigated by Bisphenol-A via suppressing inflammation and oxidative stress

The xenoestrogen bisphenol A (BPA), a commonly used industrial chemical, has been linked to endocrine disruption. The point of the study was to consider the effects of chronic BPA exposure on the respiratory system of adult female rats, and the potential mitigating benefits of Sodium hydrosulfide (NaHS), a donor of hydrogen sulfide (H2S) administration. Detect biomarkers in Bronchoalveolar lavage fluid (BALF), including total protein content, Total cell counts, Neutrophils %, ICAM (intercellular adhesion molecule)-1 and TGF-β (Transforming growth factor beta). NaHS significantly reduced pro-inflammatory cytokines (IFN-β and MCAF,) also reduce (i.e. VCAM-1, VEGF, VIM, MMP-2, MMP-9), and reduced malondialdehyde and augmented activities of SOD and GSH-PX. Notably, H2S induced a marked decrease in the expression levels of p-extracellular signal-regulated protein kinase (p-ERK), p–c-Jun N-terminal kinase (p-JNK), and p-p38, H2S inhibits BPA-induced inflammation and injury in alveolar epithelial cells. These results suggest NaHS may prevent inflammation via the suppression of the ERK/JNK/ p-p38MAPK signaling pathway, Subsequent inhibition of inflammation, epithelial cell injury, and apoptosis may be providing insight into potential avenues for the treatment of lung injury.

Hydrogen sulfide donors and inhibitors in cancer research: A state-of-the-art review

Hydrogen sulfide (H2S), a gaseous biomolecule, is considered a key player in the regulation of various essential cellular events. Normal physiology is determined by the level of endogenous H2S. Any alterations (upregulation and downregulation) to the level of endogenous H2S may lead to illness, including the onset of tumorigenesis. Over the past two decades, extensive research on the role of H2S in cancer development has affirmed the potential pharmacological means to suppress cancer progression by either inhibiting H2S synthesis in cells or exposing exogenously supplied H2S donors to treat different cancers. Some H2S donors and inhibitors release H2S or affect its synthesis. As a result, they have progressed through the development process into widespread clinical use and become increasingly important. The present study draws a detailed discussion on the types of H2S donors and inhibitors and their role in cancer research. We believe that this state-of-the-art review will empower the synthesis of H2S -based chemopreventive drugs and promote the need for further in-depth exploration of the associations between H2S and cancer treatments in clinical settings.

Beneficial effects of combination therapy with testosterone and hydrogen sulfide by reducing oxidative stress and apoptosis: Rat experimental varicocele model.

Despite the effectiveness of testosterone therapy in conditions associated with testosterone deficiency, including varicocele, several dose-dependent side effects limit the clinical use of testosterone therapy. Hydrogen sulfide, a toxic gas in high concentrations but a beneficial molecule in low concentrations, acts as both a major effector and an important inducer of testosterone. This study investigated whether a subeffective dose of testosterone combined with a subeffective dose of hydrogen sulfide donor sodium hydrosulfide (NaHS) can be effective in an experimental varicocele model through a possible additive effect. Thirty Wistar rats weighing 200-250 gr were divided into 5 groups as (n = 6/each): sham, varicocele, testosterone (200 µg/kg, 5 times per wk for 4 consecutive weeks), NaHS (15 μmol/L, daily for 4 consecutive wk) and testosterone + NaHS (200 µg/kg, 5 times per wk + 15 μmol/L, daily, both for 4 consecutive wk). All animals, except in the sham group, underwent varicocele induction. The coadministration of testosterone and NaHS significantly increased serum testosterone (10.23 0.95, p = 0.01), testicular H2S levels (608.94 21.09, p 0.001), and testicular superoxide dismutase activity (66.14 1.56, p 0.001), decreased malondialdehyde levels (0.77 0.52, p 0.001), and B-cell lymphoma 2-associated X protein to B-cell lymphoma 2 (0.16 0.01, p 0.001) protein expression ratio in the testicular tissues and improved sperm parameters and testicular histopathology compared to the varicocele group. The combination therapy of subeffective doses of testosterone and NaHS can attenuate the varicocele-induced damages by reducing testicular oxidative stress and apoptosis and thus can be considered an effective approach with fewer side effects.

Co-administration of sodium hydrosulfide and tadalafil modulates hypoxia and oxidative stress on bladder dysfunction in a rat model of bladder outlet obstruction.

This study aimed to assess the possible healing effect of combination treatment with a hydrogen sulfide (H2S) donor, sodium hydrosulfide (NaHS) plus tadalafil on partial bladder outlet obstruction (PBOO)-induced bladder dysfunction. A total of 75 male Sprague-Dawley rats aged 10-wk and 300-350g were divided into five groups; control; PBOO; PBOO+NaHS (5.6mg/kg/day, i.p., 6-wk); PBOO+tadalafil (2mg/kg/day, oral, 6-wk) and PBOO+NaHS+tadalafil. PBOO was created by partial urethral ligation. 6 weeks after obstruction, the in vitro contractile responses of the detrusor muscle and Western blotting, H2S and malondialdehyde assay were performed in bladder tissues. There was an increase in bladder weight(p<0.001) and a decrease in contractile responses to KCL(p<0.001), carbachol(p<0.01), electrical field stimulation(p<0.05) and ATP (p<0.001) in the detrusor smooth muscle of obstructed rats which was normalized after the combination treatment. Cystathionine γ-lyase and cystathionine β-synthase, and nuclear factor kappa B protein levels did not significantly differ among groups. The obstruction induced decrement in 3-mercaptopyruvate sulfur transferase protein expression(p<0.001) and H2S levels(p<0.01) as well as increment in protein expressions of neuronal nitric oxide synthase (NO, p<0.001), endothelial NOS (p<0.05), inducible NOS(p<0.001), hypoxia-inducible factor 1-alpha (p<0.01), and malondialdehyde levels (p<0.01), when combined treatment entirely normalized. Combination therapy has beneficial effects on bladder dysfunction via regulating both H2S and nitric oxide pathways as well as downregulation of oxidative stress and hypoxia. The synergistic effect of H2S and nitric oxide is likely to modulate bladder function, which supports the combined therapy for enhancing clinical outcomes in men with BPH/LUTS.

Co-assembled Nanocarriers of De Novo Thiol-Activated Hydrogen Sulfide Donors with an RGDFF Pentapeptide for Targeted Therapy of Non-Small-Cell Lung Cancer.

Hydrogen sulfide releasing agents (or H2S donors) have been recognized gasotransmitters with potent cytoprotective and anticancer properties. However, the clinical application of H2S donors has been hampered by their fast H2S-release, instability, and lack of tumor targeting, despite the unclear molecular mechanism of H2S action. Here we rationally designed an amphiphilic pentapeptide (RGDFF) to coassemble with the de novo designed thiol-activated H2S donors (CL2/3) into nanocarriers for targeted therapy of non-small-cell lung cancer, which has been proved as a one-stone-three-birds strategy. The coassembly approach simply solved the solubility issue of CL2/3 by the introduction of electron-donating groups (phenyl rings) to slow down the H2S release while dramatically improving their biocompatible interface, circulation time, slow release of H2S, and tumor targeting. Experimental results confirmed that as-prepared coassembled nanocarriers can significantly induce the intrinsic apoptotic, effectively arrest cell cycle at the G2/M phase, inhibit H2S-producing enzymes, and lead to mitochondrial dysfunction by increasing intracellular ROS production in H1299 cells. The mouse tumorigenesis experiments further confirmed the in vivo anticancer effects of the coassembled nanocarriers, and such treatment made tumors more sensitive to radiotherapy then improved the prognosis of tumor-bearing mice, which holds great promise for developing a new combined approach for NSCLC.

CD44 Receptor-Targeted and Reactive Oxygen Species-Responsive H2S Donor Micelles Based on Hyaluronic Acid for the Therapy of Renal Ischemia/Reperfusion Injury.

For the therapy attenuating renal ischemia-reperfusion (IR) injury, a novel drug delivery system was urgently needed, which could precisely deliver drugs to the pathological renal tissue. Here, we have prepared new nanomaterials with a reactive oxygen species (ROS)-responsive hydrogen sulfide (H2S) donor and hyaluronic acid that targets CD44 receptor. The novel material was synthesized and characterized via related experiments. Then, rapamycin was loaded, which inhibited kidney damage. In the in vitro study, we found that the micelles had ROS-responsiveness, biocompatibility, and cell penetration. In addition, the experimental results showed that the intracellular H2S concentration after administration was threefold higher than that of the control group. The western blot assay revealed that they have anti-inflammatory effects via H2S donor blocking the NF-κB signaling pathway. Consequently, the rising CD44 receptor-targeting and ROS-sensitive H2S donor micelles would provide a promising way for renal IR injury. This work provides a strategy for improving ischemia/reperfusion injury for pharmaceuticals.

Prophylactic Treatment with Hydrogen Sulphide Can Prevent Renal Ischemia-Reperfusion Injury in L-NAME Induced Hypertensive Rats with Cisplatin-Induced Acute Renal Failure.

(Background and Objectives): Renal ischemia perfusion injury is one of the major issues in kidney transplant. The aim of the study was to investigate the hypothesis that prophylactic treatment-with a hydrogen sulphide donor to an acute renal failure case of hypertensive rats-can minimize the ischemia reperfusion injury of the kidney which is beneficial for kidney transplant. To check this hypothesis, the present study was designed to investigate the effect of chronic administration of a hydrogen sulphide (H2S) donor and sodium hydrosulfide (NaHS) on nuclear factor kappa B (NF-kB) and inter cellular adhesion molecule-1 (ICAM-1) concentration in non-renal failure (NRF) and acute renal failure (ARF) rats in the ischemia-reperfusion injury (IRI) model of the kidney in both normotensive WKY and hypertensive rats (L-nitro arginine methyl ester (L-NAME-induced); (Materials and Methods): A total number of 48 Sprague-Dawley rats were recruited into eight groups each consisting of six animals. Each of these eight groups was used to measure systemic and renal parameters, H2S, antioxidant parameters in plasma, plasma concentration of NF-kB and ICAM-1 and renal cortical blood pressure. ARF was induced by single intraperitoneal (i.p.) cisplatin injection (5 mg/kg). Hypertension was induced by oral administration of L-NAME in drinking water for four weeks at 40 mg/kg/day. NaHS was administered (i.p) at 56 µmol/kg for five weeks while dL-propargylglycine (PAG), a H2S generation inhibitor, was administered as a single intra-peritoneal injection (50 mg/kg). An acute surgical experiment was performed for the induction of renal ischemia for 30 min by renal artery clamping followed by reperfusion for three hours; (Results): Chronic administration of NaHS attenuated the severity of ARF in both normotensive and hypertensive animals (L-NAME) along with lowering the blood pressure in hypertensive groups. NaHS improved the oxidative stress parameters such as total superoxide dismutase (T-SOD), glutathione (GSH) and reduced the malondialdehyde (MDA) concentration along with reduction of NF-kB and ICAM-1 following renal IRI; Conclusions: These findings demonstrate that H2S not only reduced the severity of cisplatin induced ARF but also reduced the severity of renal IRI by upregulating antioxidants along with decreased concentrations of NF-kB and ICAM-1 in normotensive and L-NAME induced hypertensive rats.

Sodium Thiosulphate-Loaded Liposomes Control Hydrogen Sulphide Release and Retain Its Biological Properties in Hypoxia-like Environment.

Hypoxia, or insufficient oxygen availability is a common feature in the development of a myriad of cardiovascular-related conditions including ischemic disease. Hydrogen sulphide (H2S) donors, such as sodium thiosulphate (STS), are known for their cardioprotective properties. However, H2S due to its gaseous nature, is released and cleared rapidly, limiting its potential translation to clinical settings. For the first time, we developed and characterised liposome formulations encapsulating STS and explored their potential for modulating STS uptake, H2S release and the ability to retain pro-angiogenic and biological signals in a hypoxia-like environment mirroring oxygen insufficiency in vitro. Liposomes were prepared by varying lipid ratios and characterised for size, polydispersity and charge. STS liposomal encapsulation was confirmed by HPLC-UV detection and STS uptake and H2S release was assessed in vitro. To mimic hypoxia, cobalt chloride (CoCl2) was administered in conjunction with formulated and non-formulated STS, to explore pro-angiogenic and metabolic signals. Optimised liposomal formulation observed a liposome diameter of 146.42 ± 7.34 nm, a polydispersity of 0.22 ± 0.19, and charge of 3.02 ± 1.44 mV, resulting in 25% STS encapsulation. Maximum STS uptake (76.96 ± 3.08%) from liposome encapsulated STS was determined at 24 h. Co-exposure with CoCl2 and liposome encapsulated STS resulted in increased vascular endothelial growth factor mRNA as well as protein expression, enhanced wound closure and increased capillary-like formation. Finally, liposomal STS reversed metabolic switch induced by hypoxia by enhancing mitochondrial bioenergetics. These novel findings provide evidence of a feasible controlled-delivery system for STS, thus H2S, using liposome-based nanoparticles. Likewise, data suggests that in scenarios of hypoxia, liposomal STS is a good therapeutic candidate to sustain pro-angiogenic signals and retain metabolic functions that might be impaired by limited oxygen and nutrient availability.

Polysulfides derived from the hydrogen sulfide and persulfide donor P* inhibit IL-1β-mediated inducible nitric oxide synthase signaling in ATDC5 cells: are CCAAT/enhancer-binding proteins β and δ involved in the anti-inflammatory effects of hydrogen sulfide and polysulfides?

Hydrogen sulfide (H2S) emerged as an essential signaling molecule exerting beneficial effects in various cardiovascular, neurodegenerative, or musculoskeletal diseases with an inflammatory component, such as osteoarthritis. These protective effects were initially attributed to protein S-sulfhydration, a posttranslational modification of reactive cysteine residues. However, recent studies suggest that polysulfides and not H2S are responsible for S-sulfhydration. To distinguish between H2S and polysulfide-mediated effects in this study, we used the slow-releasing H2S and persulfide donor P*, which can be decomposed into polysulfides. The effects of P* on IL-1β-induced inducible nitric oxide synthase (iNOS), a pro-inflammatory mediator in osteoarthritis, were determined by nitrite measurement, qPCR, and Western blotting in the murine chondrocyte-like cell line ATDC5. Decomposed P* significantly reduced IL-1β-induced iNOS signaling via polysulfides, independently of H2S. In line with this, the fast-releasing H2S donor NaHS was ineffective. In RAW 264.7 macrophages, similar results were obtained. P*-derived polysulfides further diminished IL-1β-induced CCAAT/enhancer-binding protein (C/EBP) β and δ expression in ATDC5 cells, which might play a critical role in P*-mediated iNOS decline. In conclusion, our data support the view that polysulfides are essential signaling molecules as well as potential mediators of H2S signaling. Moreover, we propose that C/EBPβ/δ might be a novel target involved in H2S and polysulfide-mediated anti-inflammatory signaling.

Sulfanegen stimulates 3-mercaptopyruvate sulfurtransferase activity and ameliorates Alzheimer's disease pathology and oxidative stress in vivo

Increased oxidative stress and inflammation are implicated in the pathogenesis of Alzheimer's disease. Treatment with hydrogen sulfide (H2S) and H2S donors such as sodium hydrosulfide (NaSH) can reduce oxidative stress in preclinical studies, however clinical benefits of such treatments are rather ambiguous. This is partly due to poor stability and bioavailability of the H2S donors, requiring impractically large doses that are associated with dose-limiting toxicity. Herein, we identified a bioavailable 3-mercaptopyruvate prodrug, sulfanegen, which is able to pose as a sacrificial redox substrate for 3-mercaptopyruvate sulfurtransferase (3MST), one of the H2S biosynthetic enzymes in the brain. Sulfanegen is able to mitigate toxicity emanating from oxidative insults and the Aβ1-42 peptide by releasing H2S through the 3MST pathway. When administered to symptomatic transgenic mouse model of AD (APP/PS1; 7 and 12 months) and mice that were intracerebroventricularly administered with the Aβ1-42 peptide, sulfanegen was able to reverse oxidative and neuroinflammatory consequences of AD pathology by restoring 3MST function. Quantitative neuropathological analyses confirmed significant disease modifying effect of the compound on amyloid plaque burden and brain inflammatory markers. More importantly, sulfanegen treatment attenuated progressive neurodegeneration in these mice, as evident from the restoration of TH+ neurons in the locus coeruleus. This study demonstrates a previously unknown concept that supplementation of 3MST function in the brain may be a viable approach for the management of AD. Finally, brought into the spotlight is the potential of sulfanegen as a promising AD therapeutic for future drug development efforts.

Hydrogen sulfide donor GYY4137 attenuates vascular complications in mesenteric bed of streptozotocin-induced diabetic rats

Hydrogen sulfide (H2S) has been reported to have beneficial effects in different pathological conditions. Objectives: the effects of chronic treatment of diabetic rats with GYY4137 (slow releasing H2S donor) or NaHS (fast releasing H2S donor) on the reactivity of the mesenteric bed to vasoactive agonists and the changes in its downstream effectors, ERK1/2 and p38 MAP Kinase have been investigated. In addition, the levels of nitric oxide (NO) and H2S in all groups were measured. Methods: diabetes was induced by a single intraperitoneal (ip) injection of streptozotocin (STZ; 55 mg/kg). Sprague Dawley (SD; n = 10–12/group) rats were randomly divided into six groups: control, STZ-induced diabetic rats, GYY4137-treated control, NaHS-treated control, GYY4137-treated diabetic, and NaHS-treated diabetic. After 28 days of treatment, rats were sacrificed and mesenteric beds were isolated for functional or biochemical studies. The vascular reactivity of the perfused mesenteric bed to norepinephrine, carbachol and sodium nitroprusside were determined by measurement of changes in perfusion pressure. Western blotting was performed to measure the protein expression of ERK1/2, p38, eNOS, and H2S biosynthesizing enzymes cystathionine-β-synthase and cystathionine-γ-lyase. NO and H2S levels were measured in all groups in isolated mesenteric tissues or plasma. Results: diabetes resulted in a significant increase in vasoconstrictor responses to norepinephrine (e.g., 129.6 ± 6.77 mmHg in diabetic vs 89.3 ± 8.48 mmHg in control at 10−7 dose), and carbachol-induced vasodilation was significantly reduced in diabetic mesenteric bed (e.g., 68.9 ± 4.8 mmHg in diabetic vs 90.6 ± 2.2 mmHg in control at 10−7 dose). Chronic treatment of the diabetic rats with GYY4137 resulted in a significant improvement in the response to norepinephrine (e.g., 86.66 ± 8.04 mmHg in GYY4137-treated diabetic vs 129.6 ± 6.77 mmHg in untreated diabetic at 10−7 dose) or carbachol (e.g., 84.90 ± 2.48 mmHg in GYY4137-treated diabetic vs 68.9 ± 4.8 mmHg in untreated diabetic at 10−7 dose). The biochemical studies showed a marked reduction of the protein expression of ERK and p38 and a significant upregulation of the expression of eNOS and H2S synthesizing enzymes after chronic treatment with GYY4137. Plasma levels of NO and H2S were significantly elevated after treatment with GYY4137. However, H2S production in the mesenteric bed showed a marginal elevation in diabetic tissues compared to controls. Conclusion: the results indicate that GYY4137 may be a novel therapeutic tool to prevent diabetes-associated vascular dysfunction.

HA-ADT suppresses esophageal squamous cell carcinoma progression via apoptosis promotion and autophagy inhibition

Esophageal squamous cell carcinoma (ESCC) is a major cause of cancer-related deaths. We have previously connected a non-sulfated glycosaminoglycan, hyaluronic acid (HA), with a common hydrogen sulfide (H2S) donor, 5-(4-hydroxyphenyl)-3H-1,2-dithiol-3-thione (ADT-OH), to reconstruct a novel conjugate, HA-ADT. In this study, we determined the effect of HA-ADT on the growth of ESCC. Our data suggested that HA-ADT exerted more potent effects than sodium hydrosulfide (NaHS, a fast H2S-releasing donor) and morpholin-4-ium (4-methoxyphenyl)-morpholin-4-ylsulfanylidenesulfido-λ5-phosphane (GYY4137, a slow H2S-releasing donor) on inhibiting the viability, proliferation, migration, and invasion of human ESCC cells. HA-ADT increased apoptosis by suppressing the protein expressions of phospho (p)-Ser473-protein kinase B (PKB/AKT), p-Tyr199/Tyr458-phosphatidylinositol 3-kinase (PI3K), and p-Ser2448-mammalian target of rapamycin (mTOR), but suppressed autophagy through the inhibition of the protein levels of p-Ser552-β‐catenin, p‐Ser9-glycogen synthase kinase‐3β (GSK-3β), and Wnt3a in human ESCC cells. In addition, HA-ADT was more effective in terms of the growth inhibition of human ESCC xenograft tumor than NaHS and GYY4137. In conclusion, HA-ADT can suppress ESCC progression via apoptosis promotion and autophagy inhibition. HA-ADT might be efficacious for the treatment of cancer.

The Effects of H2S and Recombinant Human Hsp70 on Inflammation Induced by SARS and Other Agents In Vitro and In Vivo.

The ongoing epidemic caused by SARS-CoV-2 infection led to the search for fundamentally new ways and means to combat inflammation and other pathologies caused by this virus. Using a cellular model of lipopolysaccharide (LPS)-induced sepsis (human promonocytes), we showed that both a hydrogen sulfide donor (sodium thiosulfate, STS) and a recombinant Heat shock protein 70 (rHsp70) effectively block all major inflammatory mediators when administrated before and after LPS challenge. The protective anti-inflammatory effect of rHsp70 and H2S was also confirmed in vivo using various animal models of pneumonia. Specifically, it was found that rHsp70 injections prevented the development of the acute respiratory distress syndrome in highly pathogenic pneumonia in mice, increased animal survival, and reduced the number of Programmed death-1 (PD-1)-positive T-lymphocytes in peripheral blood. Based on our model experiments we developed a combined two-phase therapeutic approach for the treatment of COVID-19 patients. This procedure includes the inhalation of hot helium–oxygen mixtures for induction of endogenous Hsp70 in the first phase and STS inhalation in the second phase. The use of this approach has yielded positive results in COVID-19 patients, reducing the area of lung lesions, restoring parameters of innate immunity and T-cell immune response against coronavirus infection, and preventing the development of pulmonary fibrosis and immune exhaustion syndrome.

Titanium Sulfide Nanosheets Serve as Cascade Bioreactors for H2 S-Mediated Programmed Gas-Sonodynamic Cancer Therapy.

Gas‐mediated sonodynamic therapy (SDT) has the potential to become an effective strategy to improve the therapeutic outcome and survival rate of cancer patients. Herein, titanium sulfide nanosheets (TiS X NSs) are prepared as cascade bioreactors for sequential gas–sonodynamic cancer therapy. TiS X NSs themselves as hydrogen sulfide (H2S) donors can burst release H2S gas. Following H2S generation, TiS X NSs are gradually degraded to become S‐defective and partly oxidized into TiO X on their surface, which endows TiS X NSs with high sonodynamic properties under ultrasound (US) irradiation. In vitro and in vivo experiments show the excellent therapeutic effects of TiS X NSs. In detail, large amounts of H2S gas and reactive oxygen species (ROS) can simultaneously inhibit mitochondrial respiration and ATP synthesis, leading to cancer cell apoptosis. Of note, H2S gas also plays important roles in modulating and activating the immune system to effectively inhibit pulmonary metastasis. Finally, the metabolizable TiS X NSs are excreted out of the body without inducing any significant long‐term toxicity. Collectively, this work establishes a cascade bioreactor of TiS X NSs with satisfactory H2S release ability and excellent ROS generation properties under US irradiation for programmed gas–sonodynamic cancer therapy.

Development of hydrogen sulfide donors for anti-atherosclerosis therapeutics research: Challenges and future priorities.

Hydrogen sulfide (H2S), a gas transmitter found in eukaryotic organisms, plays an essential role in several physiological processes. H2S is one of the three primary biological gas transmission signaling mediators, along with nitric oxide and carbon monoxide. Several animal and in vitro experiments have indicated that H2S can prevent coronary endothelial mesenchymal transition, reduce the expression of endothelial cell adhesion molecules, and stabilize intravascular plaques, suggesting its potential role in the treatment of atherosclerosis (AS). H2S donors are compounds that can release H2S under certain circumstances. Development of highly targeted H2S donors is a key imperative as these can allow for in-depth evaluation of the anti-atherosclerotic effects of exogenous H2S. More importantly, identification of an optimal H2S donor is critical for the creation of H2S anti-atherosclerotic prodrugs. In this review, we discuss a wide range of H2S donors with anti-AS potential along with their respective transport pathways and design-related limitations. We also discuss the utilization of nano-synthetic technologies to manufacture H2S donors. This innovative and effective design example sheds new light on the production of highly targeted H2S donors.