Mitochondria-targeted hydrogen sulfide donor AP39 improves neurological outcomes after cardiac arrest in mice

Copyright © 2015 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in . Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Nitric Oxide, Vol. 49, pp. 90–96 (2015), DOI:10.1016/j.niox.2015.05.001Aims Mitochondria-targeted hydrogen sulfide donor AP39, [(10-oxo-10-(4-(3-thioxo-3H-1,2-dithiol-5yl)phenoxy)decyl) triphenylphosphonium bromide], exhibits cytoprotective effects against oxidative stress in vitro. We examined whether or not AP39 improves the neurological function and long term survival in mice subjected to cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). Methods Adult C57BL/6 male mice were subjected to 8 min of CA and subsequent CPR. We examined the effects of AP39 (10, 100, 1000 nmol kg−1) or vehicle administered intravenously at 2 min before CPR (Experiment 1). Systemic oxidative stress levels, mitochondrial permeability transition, and histological brain injury were assessed. We also examined the effects of AP39 (10, 1000 nmol kg−1) or vehicle administered intravenously at 1 min after return of spontaneous circulation (ROSC) (Experiment 2). ROSC was defined as the return of sinus rhythm with a mean arterial pressure >40 mm Hg lasting at least 10 seconds. Results Vehicle treated mice subjected to CA/CPR had poor neurological function and 10-day survival rate (Experiment 1; 15%, Experiment 2; 23%). Administration of AP39 (100 and 1000 nmol kg−1) 2 min before CPR significantly improved the neurological function and 10-day survival rate (54% and 62%, respectively) after CA/CPR. Administration of AP39 before CPR attenuated mitochondrial permeability transition pore opening, reactive oxygen species generation, and neuronal degeneration after CA/CPR. Administration of AP39 1 min after ROSC at 10 nmol kg−1, but not at 1000 nmol kg−1, significantly improved the neurological function and 10-day survival rate (69%) after CA/CPR. Conclusion The current results suggest that administration of mitochondria-targeted sulfide donor AP39 at the time of CPR or after ROSC improves the neurological function and long term survival rates after CA/CPR by maintaining mitochondrial integrity and reducing oxidative stress.National Institutes of Healt

Sulfide Catabolism Ameliorates Hypoxic Brain Injury

The mammalian brain is highly vulnerable to oxygen deprivation, yet the mechanism underlying the brain’s sensitivity to hypoxia is incompletely understood. Hypoxia induces accumulation of hydrogen sulfide, a gas that inhibits mitochondrial respiration. Here, we show that, in mice, rats, and naturally hypoxia-tolerant ground squirrels, the sensitivity of the brain to hypoxia is inversely related to the levels of sulfide:quinone oxidoreductase (SQOR) and the capacity to catabolize sulfide. Silencing SQOR increased the sensitivity of the brain to hypoxia, whereas neuron-specific SQOR expression prevented hypoxia-induced sulfide accumulation, bioenergetic failure, and ischemic brain injury. Excluding SQOR from mitochondria increased sensitivity to hypoxia not only in the brain but also in heart and liver. Pharmacological scavenging of sulfide maintained mitochondrial respiration in hypoxic neurons and made mice resistant to hypoxia. These results illuminate the critical role of sulfide catabolism in energy homeostasis during hypoxia and identify a therapeutic target for ischemic brain injury

Trapping hydrogen sulfide (H₂S) with diselenides: the application in the design of fluorescent probes

Here we report a unique reaction between phenyl diselenide-ester substrates and H2S to form 1,2-benzothiaselenol-3-one. This reaction proceeded rapidly under mild conditions. Thiols could also react with the diselenide substrates. However, the resulted S-Se intermediate retained high reactivity toward H2S and eventually led to the same cyclized product 1,2-benzothiaselenol-3-one. Based on this reaction two fluorescent probes were developed and showed high selectivity and sensitivity for H2S. The presence of thiols was found not to interfere with the detection process

Trapping Hydrogen Sulfide (H2S) with Diselenides: The Application in the Design of Fluorescent Probes

Here we report a unique reaction between phenyl diselenide-ester substrates and H2S to form 1,2-benzothiaselenol-3-one. This reaction proceeded rapidly under mild conditions. Thiols could also react with the diselenide substrates. However, the resulted S–Se intermediate retained high reactivity toward H2S and eventually led to the same cyclized product 1,2-benzothiaselenol-3-one. Based on this reaction two fluorescent probes were developed and showed high selectivity and sensitivity for H2S. The presence of thiols was found not to interfere with the detection process

Sodium thiosulfate attenuates acute lung injury in mice

Acute lung injury is characterized by neutrophilic inflammation and increased lung permeability. Thiosulfate is a stable metabolite of hydrogen sulfide, a gaseous mediator that exerts antiinflammatory effects. Although sodium thiosulfate (STS) has been used as an antidote, the effect of STS on acute lung injury is unknown. The authors assessed the effects of STS on mice lung and vascular endothelial cells subjected to acute inflammation. Lung injury was assessed in mice challenged with intratracheal lipopolysaccharide or subjected to cecal ligation and puncture with or without STS. Effects of STS on endothelial permeability and the production of inflammatory cytokines and reactive oxygen species were examined in cultured endothelial cells incubated with lipopolysaccharide or tumor necrosis factor-α. Levels of sulfide and sulfane sulfur were measured using novel fluorescence probes. STS inhibited lipopolysaccharide-induced production of cytokines (interleukin-6 [pg/ml]; 313±164, lipopolysaccharide; 79±27, lipopolysaccharide+STS [n=10]), lung permeability, histologic lung injury, and nuclear factor-κB activation in the lung. STS also prevented up-regulation of interleukin-6 in the mouse lung subjected to cecal ligation and puncture. In endothelial cells, STS increased intracellular levels of sulfide and sulfane sulfur and inhibited lipopolysaccharide or tumor necrosis factor-α-induced production of cytokines and reactive oxygen species. The beneficial effects of STS were associated with attenuation of the lipopolysaccharide-induced nuclear factor-κB activation through the inhibition of tumor necrosis factor receptor-associated factor 6 ubiquitination. STS exerts robust antiinflammatory effects in mice lung and vascular endothelium. The results suggest a therapeutic potential of STS in acute lung injury

Sodium Thiosulfate Attenuates Acute Lung Injury in Mice

BACKGROUND: Acute lung injury (ALI) is characterized by neutrophilic inflammation and increased lung permeability. Thiosulfate is a stable metabolite of hydrogen sulfide, a gaseous mediator that exerts anti-inflammatory effects. While sodium thiosulfate (STS) has been used as an antidote, the effect of STS in ALI is unknown. We assessed the effects of STS in mice lung and vascular endothelial cells subjected to acute inflammation. METHODS: Lung injury was assessed in mice challenged with intratracheal lipopolysaccharide or subjected to cecal ligation and puncture with or without STS. Effects of STS on endothelial permeability, and the production of inflammatory cytokines and reactive oxygen species were examined in cultured endothelial cells incubated with lipopolysaccharide or tumor necrosis factor alpha (TNFα). Levels of sulfide and sulfane sulfur were measured using novel fluorescence probes. RESULTS: STS inhibited lipopolysaccharide-induced production of cytokines (Interleukin-6 (pg/ml); 313±164, lipopolysaccharide; 79±27, lipopolysaccharide + STS (n=10)), lung permeability, histological lung injury, and nuclear factor-κB activation in the lung. STS also prevented upregulation of Interleukin-6 in the mouse lung subjected to cecal ligation and puncture. In endothelial cells, STS increased intracellular levels of sulfide and sulfane sulfur, inhibited lipopolysaccharide or TNFα-induced production of cytokines and reactive oxygen species. The beneficial effects of STS were associated with attenuation of the lipopolysaccharide-induced nuclear factor-κB activation through the inhibition of TNF receptor-associated factor 6 ubiquitination. CONCLUSIONS: STS exerts robust anti-inflammatory effects in mice lung and vascular endothelium. Our results suggest a therapeutic potential of STS in ALI

Cytoprotective effects of hydrogen sulfide-releasing N-methyl-d-aspartate receptor antagonists mediated by intracellular sulfane sulfur

Hydrogen sulfide (H2S) exerts a host of biological effects ranging from cytotoxicity to cytoprotection. Cytotoxicity of H2S in neurodegenerative diseases may be mediated by N-methyl-d-aspartate receptor (NMDAR) activation. To exploit cytoprotective effects of H2S while minimizing its toxicity, we synthesized a series of H2S-releasing NMDAR antagonists and examined their effects against 1-methyl-4-phenylpyridinium (MPP+)-induced cell death, a cellular model of Parkinson's disease. We observed that cytoprotective effects of H2S-releasing NMDAR antagonists correlated with their ability to increase intracellular sulfane sulfur, but not H2S, levels. These studies suggest that H2S-donor compounds that increase intracellular sulfane sulfur levels are potentially useful neuroprotective agents against neurodegenerative diseases