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Background: Advanced age is unequivocally linked to the development of cardiovascular disease; however, the mechanisms resulting in reduced endothelial cell regeneration remain poorly understood. Here, we investigated novel mechanisms involved in endothelial cell senescence that impact endothelial cell transcription and vascular repair after injury., Methods: Native endothelial cells were isolated from young (20±3.4 years) and aged (80±2.3 years) individuals and subjected to molecular analyses to assess global transcriptional and metabolic changes. In vitro studies were conducted using primary human and murine endothelial cells. A murine aortic re-endothelialization model was used to examine endothelial cell regenerative capacity in vivo., Results: RNA sequencing of native endothelial cells revealed that aging resulted in p53-mediated reprogramming to express senescence-associated genes and suppress glycolysis. Reduced glucose uptake and ATP contributed to attenuated assembly of the telomerase complex, which was required for endothelial cell proliferation. Enhanced p53 activity in aging was linked to its acetylation on K120 due to enhanced activity of the acetyltransferase MOZ (monocytic leukemic zinc finger). Mechanistically, p53 acetylation and translocation were, at least partially, attributed to the loss of the vasoprotective enzyme, CSE (cystathionine γ-lyase). CSE physically anchored p53 in the cytosol to prevent its nuclear translocation and CSE absence inhibited AKT (Protein kinase B)-mediated MOZ phosphorylation, which in turn increased MOZ activity and subsequently p53 acetylation. In mice, the endothelial cell-specific deletion of CSE activated p53, induced premature endothelial senescence, and arrested vascular repair after injury. In contrast, the adeno-associated virus 9-mediated re-expression of an active CSE mutant retained p53 in the cytosol, maintained endothelial glucose metabolism and proliferation, and prevented endothelial cell senescence. Adenoviral overexpression of CSE in native endothelial cells from aged individuals maintained low p53 activity and reactivated telomerase to revert endothelial cell senescence., Conclusions: Aging-associated impairment of vascular repair is partly determined by the vasoprotective enzyme CSE., Competing Interests: Disclosures None.

Background: Aortic aneurysm and aortic dissection (AAD) are life-threatening vascular diseases, with endothelium being the primary target for AAD treatment. Protein S-sulfhydration is a newly discovered posttranslational modification whose role in AAD has not yet been defined. This study aims to investigate whether protein S-sulfhydration in the endothelium regulates AAD and its underlying mechanism., Methods: Protein S-sulfhydration in endothelial cells (ECs) during AAD was detected and hub genes regulating homeostasis of the endothelium were identified. Clinical data of patients with AAD and healthy controls were collected, and the level of the cystathionine γ lyase (CSE)/hydrogen sulfide (H 2 S) system in plasma and aortic tissue were determined. Mice with EC-specific CSE deletion or overexpression were generated, and the progression of AAD was determined. Unbiased proteomics and coimmunoprecipitation combined with mass spectrometry analysis were conducted to determine the upstream regulators of the CSE/H 2 S system and the findings were confirmed in transgenic mice., Results: Higher plasma H 2 S levels were associated with a lower risk of AAD, after adjustment for common risk factors. CSE was reduced in the endothelium of AAD mouse and aorta of patients with AAD. Protein S-sulfhydration was reduced in the endothelium during AAD and protein disulfide isomerase (PDI) was the main target. S-sulfhydration of PDI at Cys343 and Cys400 enhanced PDI activity and mitigated endoplasmic reticulum stress. EC-specific CSE deletion was exacerbated, and EC-specific overexpression of CSE alleviated the progression of AAD through regulating the S-sulfhydration of PDI. ZEB2 (zinc finger E-box binding homeobox 2) recruited the HDAC1-NuRD complex (histone deacetylase 1-nucleosome remodeling and deacetylase) to repress the transcription of CTH , the gene encoding CSE, and inhibited PDI S-sulfhydration. EC-specific HDAC1 deletion increased PDI S-sulfhydration and alleviated AAD. Increasing PDI S-sulfhydration with the H 2 S donor GYY4137 or pharmacologically inhibiting HDAC1 activity with entinostat alleviated the progression of AAD., Conclusions: Decreased plasma H 2 S levels are associated with an increased risk of aortic dissection. The endothelial ZEB2-HDAC1-NuRD complex transcriptionally represses CTH , impairs PDI S-sulfhydration, and drives AAD. The regulation of this pathway effectively prevents AAD progression.

Background: Sodium thiosulfate (Na2S2O3) is a clinically established drug with antioxidant and sulphide-releasing properties. Na2S2O3 mediated neuro- and cardioprotective effects in ischemia/reperfusion models and anti-inflammatory effects in LPS-induced acute lung injury. Moreover, Na2S2O3 improved lung function during resuscitation from hemorrhagic shock in swine with pre-existing atherosclerosis, characterized by decreased expression of cystathionine γ-lyase (CSE), a major source of hydrogen sulfide (H2S) synthesis in the vasculature. Based on these findings, we investigated the effects of Na2S2O3 administration during resuscitation from trauma-and-hemorrhage in mice under conditions of whole body CSE deficit., Methods: After blast wave-induced blunt chest trauma and surgical instrumentation, CSE knockout (CSE-/-) mice underwent 1 h of hemorrhagic shock (MAP 35 ± 5 mm Hg). At the beginning of resuscitation comprising retransfusion, norepinephrine support and lung-protective mechanical ventilation, animals received either i.v. Na2S2O3 (0.45 mg g-1, n = 12) or vehicle (saline, n = 13). Hemodynamics, acid-base status, metabolism using stable isotopes, and visceral organ function were assessed. Blood and organs were collected for analysis of cytokines, mitochondrial respiratory capacity, and immunoblotting., Results: Na2S2O3 treatment improved arterial paO2 (P = 0.03) coinciding with higher lung tissue glucocorticoid receptor expression. Norepinephrine requirements were lower in the Na2S2O3 group (P < 0.05), which was associated with lower endogenous glucose production and higher urine output. Na2S2O3 significantly increased renal tissue IκBα and heme oxygenase-1 expression, whereas it lowered kidney IL-6 and MCP-1 levels., Conclusion: Na2S2O3 exerted beneficial effects during resuscitation of murine trauma-and-hemorrhage in CSE-/- mice, confirming and extending the previously described organ-protective and anti-inflammatory properties of Na2S2O3. The findings make Na2S2O3 a potentially promising therapeutic option in the context of impaired CSE activity and/or reduced endogenous H2S availability., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by the Shock Society.)

Background: In vascular endothelial cells, cysteine metabolism by the cystathionine γ lyase (CSE), generates hydrogen sulfide-related sulfane sulfur compounds (H 2 S n ), that exert their biological actions via cysteine S -sulfhydration of target proteins. This study set out to map the " S -sulfhydrome" (ie, the spectrum of proteins targeted by H 2 S n ) in human endothelial cells., Methods: Liquid chromatography with tandem mass spectrometry was used to identify S -sulfhydrated cysteines in endothelial cell proteins and β3 integrin intraprotein disulfide bond rearrangement. Functional studies included endothelial cell adhesion, shear stress-induced cell alignment, blood pressure measurements, and flow-induced vasodilatation in endothelial cell-specific CSE knockout mice and in a small collective of patients with endothelial dysfunction., Results: Three paired sample sets were compared: (1) native human endothelial cells isolated from plaque-free mesenteric arteries (CSE activity high) and plaque-containing carotid arteries (CSE activity low); (2) cultured human endothelial cells kept under static conditions or exposed to fluid shear stress to decrease CSE expression; and (3) cultured endothelial cells exposed to shear stress to decrease CSE expression and treated with solvent or the slow-releasing H 2 S n donor, SG1002. The endothelial cell " S -sulfhydrome" consisted of 3446 individual cysteine residues in 1591 proteins. The most altered family of proteins were the integrins and focusing on β3 integrin in detail we found that S -sulfhydration affected intraprotein disulfide bond formation and was required for the maintenance of an extended-open conformation of the β leg. β3 integrin S -sulfhydration was required for endothelial cell mechanotransduction in vitro as well as flow-induced dilatation in murine mesenteric arteries. In cultured cells, the loss of S -sulfhydration impaired interactions between β3 integrin and Gα13 (guanine nucleotide-binding protein subunit α 13), resulting in the constitutive activation of RhoA (ras homolog family member A) and impaired flow-induced endothelial cell realignment. In humans with atherosclerosis, endothelial function correlated with low H 2 S n generation, impaired flow-induced dilatation, and failure to detect β3 integrin S -sulfhydration, all of which were rescued after the administration of an H 2 S n supplement., Conclusions: Vascular disease is associated with marked changes in the S -sulfhydration of endothelial cell proteins involved in mediating responses to flow. Short-term H 2 S n supplementation improved vascular reactivity in humans highlighting the potential of interfering with this pathway to treat vascular disease.

Background: Hydrogen sulfide (H 2 S) has antihypertension and anti-inflammatory effects, and its endogenous-generation key enzyme cystathionine γ lyase (CSE) is expressed in CD4 + T cells. However, the role of CD4 + T-cell endogenous CSE/H 2 S in the development of hypertension is unclear., Methods: Peripheral blood lymphocytes were isolated from hypertensive patients or spontaneously hypertensive rats, then H 2 S production and expression of its generation enzymes, cystathionine β synthase and CSE, were measured to determine the major H 2 S generation system changes in hypertension. Mice with CSE-specific knockout in T cells (conditional knockout, by CD4 cre mice hybridization) and CD4 null mice were generated for investigating the pathophysiological relevance of the CSE/H 2 S system., Results: In lymphocytes, H 2 S from CSE, but not cystathionine β synthase, responded to blood pressure changes, supported by lymphocyte CSE protein changes and a negative correlation between H 2 S production with systolic blood pressure and diastolic blood pressure, but positive correlation with the serum level of interleukin 10 (an anti-inflammatory cytokine). Deletion of CSE in T cells elevated BP (5-8 mm Hg) under the physiological condition and exacerbated angiotensin II-induced hypertension. In keeping with hypertension, mesenteric artery dilation impaired association with arterial inflammation, an effect attributed to reduced immunoinhibitory T regulatory cell (Treg) numbers in the blood and kidney, thus causing excess CD4 + and CD8 + T cell infiltration in perivascular adipose tissues and kidney. CSE knockout CD4 + T cell transfer into CD4 null mice, also showed the similar phenotypes' confirming the role of endogenous CSE/H 2 S action. Adoptive transfer of Tregs (to conditional knockout mice) reversed hypertension, vascular relaxation impairment, and immunocyte infiltration, which confirmed that conditional knockout-induced hypertension was attributable, in part, to the reduced Treg numbers. Mechanistically, endogenous CSE/H 2 S promoted Treg differentiation and proliferation by activating AMP-activated protein kinase. In part, it depended on activation of its upstream kinase, liver kinase B1, by sulfhydration to facilitate its substrate binding and phosphorylation., Conclusion: The constitutive sulfhydration of liver kinase B1 by CSE-derived H 2 S activates its target kinase, AMP-activated protein kinase, and promotes Treg differentiation and proliferation, which attenuates the vascular and renal immune-inflammation, thereby preventing hypertension.

Hydrogen sulfide has emerged as an important gaseous signaling molecule and a regulator of critical biological processes. However, the physiological significance of hydrogen sulfide metabolites such as persulfides, polysulfides, and other reactive sulfur species (RSS) has only recently been appreciated. Emerging evidence suggests that these RSS molecules may have similar or divergent regulatory roles compared with hydrogen sulfide in various biological activities. However, the chemical nature of persulfides and polysulfides is complex and remains poorly understood within cardiovascular and other pathophysiological conditions. Recent reports suggest that RSS can be produced endogenously, with different forms having unique chemical properties and biological implications involving diverse cellular responses such as protein biosynthesis, cell-cell barrier functions, and mitochondrial bioenergetics. Enzymes of the transsulfuration pathway, CBS (cystathionine beta-synthase) and CSE (cystathionine gamma-lyase), may also produce RSS metabolites besides hydrogen sulfide. Moreover, CARSs (cysteinyl-tRNA synthetase) are also able to generate protein persulfides via cysteine persulfide (CysSSH) incorporation into nascently formed polypeptides suggesting a new biologically relevant amino acid. This brief review discusses the biochemical nature and potential roles of RSS, associated oxidative stress redox signaling, and future research opportunities in cardiovascular disease.

Background: Hydrogen sulfide (H 2 S), generated by cystathionine γ lyase (CSE), is an important endogenous regulator of vascular function. The aim of the present study was to investigate the control and consequences of CSE activity in endothelial cells under physiological and proatherogenic conditions., Methods: Endothelial cell CSE knockout mice were generated, and lung endothelial cells were studied in vitro (gene expression, protein sulfhydration, and monocyte adhesion). Mice were crossed onto the apolipoprotein E-deficient background, and atherogenesis (partial carotid artery ligation) was monitored over 21 days. CSE expression, H 2 S bioavailability, and amino acid profiling were also performed with human material., Results: The endothelial cell-specific deletion of CSE selectively increased the expression of CD62E and elevated monocyte adherence in the absence of an inflammatory stimulus. Mechanistically, CD62E mRNA was more stable in endothelial cells from CSE-deficient mice, an effect attributed to the attenuated sulfhydration and dimerization of the RNA-binding protein human antigen R. CSE expression was upregulated in mice after partial carotid artery ligation and in atheromas from human subjects. Despite the increase in CSE protein, circulating and intraplaque H 2 S levels were reduced, a phenomenon that could be attributed to the serine phosphorylation (on Ser377) and inhibition of the enzyme, most likely resulting from increased interleukin-1β. Consistent with the loss of H 2 S, human antigen R sulfhydration was attenuated in atherosclerosis and resulted in the stabilization of human antigen R-target mRNAs, for example, CD62E and cathepsin S, both of which are linked to endothelial cell activation and atherosclerosis. The deletion of CSE from endothelial cells was associated with the accelerated development of endothelial dysfunction and atherosclerosis, effects that were reversed on treatment with a polysulfide donor. Finally, in mice and humans, plasma levels of the CSE substrate l-cystathionine negatively correlated with vascular reactivity and H 2 S levels, indicating its potential use as a biomarker for vascular disease., Conclusions: The constitutive S-sulfhydration of human antigen R (on Cys13) by CSE-derived H 2 S prevents its homodimerization and activity, which attenuates the expression of target proteins such as CD62E and cathepsin S. However, as a consequence of vascular inflammation, the beneficial actions of CSE-derived H 2 S are lost owing to the phosphorylation and inhibition of the enzyme.

Objective- Flow patterns differentially regulate endothelial cell phenotype, with laminar flow promoting vasodilation and disturbed flow promoting endothelial proinflammatory activation. CSE (cystathionine γ-lyase), a major source of hydrogen sulfide (H 2 S) in endothelial cells, critically regulates cardiovascular function, by both promoting vasodilation and reducing endothelial activation. Therefore, we sought to investigate the role of CSE in the endothelial response to flow. Approach and Results- Wild-type C57Bl/6J and CSE knockout ( CSE -/- ) mice underwent partial carotid ligation to induce disturbed flow in the left carotid. In addition, endothelial cells isolated from wild-type and CSE -/- mice were exposed to either laminar or oscillatory flow, an in vitro model of disturbed flow. Interestingly, laminar flow significantly reduced CSE expression in vitro, and only disturbed flow regions show discernable CSE protein expression in vivo, correlating with enhanced H 2 S production in wild-type C57BL/6J but not CSE -/- mice. Lack of CSE limited disturbed flow-induced proinflammatory gene expression (ICAM-1[intercellular adhesion molecule 1], VCAM-1 [vascular cell adhesion molecular 1]) and monocyte infiltration and CSE -/- endothelial cells showed reduced NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activation and proinflammatory gene expression in response to oscillatory flow in vitro. In addition, CSE -/- mice showed reduced inward remodeling after partial carotid ligation. CSE -/- mice showed elevated vascular nitrite levels (measure of nitric oxide [NO]) in the unligated carotids, suggesting an elevation in baseline NO production, and the NO scavenger 2-(4-carboxyphenyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazolyl-1-oxy-3-oxide normalized the reduced inward remodeling, but not inflammation, of ligated carotids in CSE -/- mice. Conclusions- CSE expression in disturbed flow regions critically regulates both endothelial activation and flow-dependent vascular remodeling, in part through altered NO availability.

Objective: The function of perivascular adipose tissue as an anticontractile mediator in the microvasculature is lost during obesity. Obesity results in inflammation and recruitment of proinflammatory macrophages to the perivascular adipose tissue that is paralleled by depletion of the vasorelaxant signaling molecule hydrogen sulfide (H 2 S) in the vessel. The current objective was to assess the role of macrophages in determining vascular [H 2 S] and defining how this impinged on vasodilation., Approach and Results: Contractility and [H 2 S] were measured in mesenteric resistance arterioles from lean and obese mice by using pressure myography and confocal microscopy, respectively. Vasodilation was impaired and smooth muscle and endothelial [H 2 S] decreased in vessels from obese mice compared with those from lean controls. Coculturing vessels from lean mice with macrophages from obese mice, or macrophage-conditioned media, recapitulated obese phenotypes in vessels. These effects were mediated by low molecular weight species and dependent on macrophage inducible nitric oxide synthase activity., Conclusions: The inducible nitric oxide synthase activity of perivascular adipose tissue-resident proinflammatory macrophages promotes microvascular endothelial dysfunction by reducing the bioavailability of H 2 S in the vessel. These findings support a model in which vascular H 2 S depletion underpins the loss of perivascular adipose tissue anticontractile function in obesity., (© 2017 American Heart Association, Inc.)

Pretraumatic cigarette smoke (CS) exposure aggravates posttraumatic acute lung injury (ALI). Cystathionine-γ-lyase (CSE) protects against ALI and CS exposure-induced chronic obstructive lung disease (COPD). Therefore, we tested the hypothesis whether genetic CSE knockout (CSE) would aggravate posttraumatic ALI after CS exposure. After 3 to 4 weeks of CS exposure, anesthetized wild-type (WT) and CSE mice underwent blunt chest trauma, surgical instrumentation and 4 h of lung-protective mechanical ventilation. We measured hemodynamics, lung mechanics, gas exchange, metabolism, and acid-base status together with blood and tissue cytokine and chemokine levels, tissue expression of mediator proteins, parameters of oxidative and nitrosative stress, and histology. CSE mice without CS exposure showed higher cytokine and chemokine levels, and this was further enhanced by CS exposure, particularly in males. CS exposure in WT mice aggravated posttraumatic alveolar membrane thickening, dystelectasis, and inflammatory cell accumulation, which was associated with higher thoracopulmonary compliance. Pretraumatic CS exposure in CSE mice produced a similar response, except for less alveolar membrane thickening, most likely due to lung hyperinflation. CS-exposed WT mice showed the most pronounced metabolic acidosis, while CS exposure in CSE mice resulted in the lowest blood glucose levels. Urinary output and anesthesia rate were highest in male CS-exposed CSE animals. In conclusion, in murine acute-on-chronic pulmonary disease, CSE knockout aggravated posttraumatic inflammation, which was further worsened upon pretraumatic CS exposure, and this effect was particularly pronounced in males. Hence, maintaining CSE expression is critically important for stress adaptation during ALI and CS-induced COPD, most likely in a gender-dependent manner.

Objective: Clinical evidence has linked vascular calcification in advanced atherosclerotic plaques with overt cardiovascular disease and mortality. Bone resorbing monocyte-derived osteoclast-like cells are sparse in these plaques, indicating that their differentiation capability could be suppressed. Here, we seek to characterize the process of osteoclastogenesis by identifying novel regulators and pathways, with the aim of exploring possible strategies to reduce calcification., Approach and Results: We used a quantitative mass spectrometry strategy, tandem mass tagging, to quantify changes in the proteome of osteoclast-like cells differentiated from RAW264.7 cells in response to, receptor activator of nuclear factor κ-B ligand induction, a common in vitro model for osteogenesis. More than 4000 proteins were quantified, of which 138 were identified as novel osteoclast-related proteins. We selected 5 proteins for subsequent analysis (cystathionine γ-lyase [Cth/CSE], EGF-like repeat and discoidin I-like domain-containing protein 3, integrin α FG-GAP repeat containing 3, adseverin, and serpinb6b) and show that gene expression levels are also increased. Further analysis of the CSE transcript profile reveals an early onset of an mRNA increase. Silencing of CSE by siRNA and dl-propargylglycine, a CSE inhibitor, attenuated receptor activator of nuclear factor κ-B ligand-induced tartrate-resistant acid phosphatase type 5 activity and pit formation, suggesting that CSE is a potent inducer of calcium resorption. Moreover, knockdown of CSE suppressed expression of osteoclast differentiation markers., Conclusions: Our large-scale proteomics study identified novel candidate regulators or markers for osteoclastogenesis and demonstrated that CSE may act in early stages of osteoclastogenesis.

Background: Cystathionine γ-lyase (CSE) produces hydrogen sulfide (H2S) in the cardiovascular system. The deficiency of CSE in mice leads to a decreased endogenous H2S level, an age-dependent increase in blood pressure, and impaired endothelium-dependent vasorelaxation. To date, there is no direct evidence for a causative role of altered metabolism of endogenous H2S in atherosclerosis development., Methods and Results: Six-week-old CSE gene knockout and wild-type mice were fed with either a control chow or atherogenic paigen-type diet for 12 weeks. Plasma lipid profile and homocysteine levels, blood pressure, oxidative stress, atherosclerotic lesion size in the aortic roots, cell proliferation, and adhesion molecule expression were then analyzed. CSE-knockout mice fed with atherogenic diet developed early fatty streak lesions in the aortic root, elevated plasma levels of cholesterol and low-density lipoprotein cholesterol, hyperhomocysteinemia, increased lesional oxidative stress and adhesion molecule expression, and enhanced aortic intimal proliferation. Treatment of CSE-knockout mice with NaHS, but not N-acetylcysteine or ezetimibe, inhibited the accelerated atherosclerosis development. Double knockout of CSE and apolipoprotein E gene expression in mice exacerbated atherosclerosis development more than that in the mice with only apolipoprotein E or CSE knockout., Conclusions: Endogenously synthesized H2S protects vascular tissues from atherogenic damage by reducing vessel intimal proliferation and inhibiting adhesion molecule expression. Decreased endogenous H2S production predisposes the animals to vascular remodeling and early development of atherosclerosis. The CSE/H2S pathway is an important therapeutic target for protection against atherosclerosis.

Background: Cystathionine γ-lyase (CSE) produces H2S via enzymatic conversion of L-cysteine and plays a critical role in cardiovascular homeostasis. We investigated the effects of genetic modulation of CSE and exogenous H2S therapy in the setting of pressure overload-induced heart failure., Methods and Results: Transverse aortic constriction was performed in wild-type, CSE knockout, and cardiac-specific CSE transgenic mice. In addition, C57BL/6J or CSE knockout mice received a novel H2S donor (SG-1002). Mice were followed up for 12 weeks with echocardiography. We observed a >60% reduction in myocardial and circulating H2S levels after transverse aortic constriction. CSE knockout mice exhibited significantly greater cardiac dilatation and dysfunction than wild-type mice after transverse aortic constriction, and cardiac-specific CSE transgenic mice maintained cardiac structure and function after transverse aortic constriction. H2S therapy with SG-1002 resulted in cardioprotection during transverse aortic constriction via upregulation of the vascular endothelial growth factor-Akt-endothelial nitric oxide synthase-nitric oxide-cGMP pathway with preserved mitochondrial function, attenuated oxidative stress, and increased myocardial vascular density., Conclusions: Our results demonstrate that H2S levels are decreased in mice in the setting of heart failure. Moreover, CSE plays a critical role in the preservation of cardiac function in heart failure, and oral H2S therapy prevents the transition from compensated to decompensated heart failure in part via upregulation of endothelial nitric oxide synthase and increased nitric oxide bioavailability.

Rationale: Nitric oxide, the classic endothelium-derived relaxing factor (EDRF), acts through cyclic GMP and calcium without notably affecting membrane potential. A major component of EDRF activity derives from hyperpolarization and is termed endothelium-derived hyperpolarizing factor (EDHF). Hydrogen sulfide (H(2)S) is a prominent EDRF, since mice lacking its biosynthetic enzyme, cystathionine γ-lyase (CSE), display pronounced hypertension with deficient vasorelaxant responses to acetylcholine., Objective: The purpose of this study was to determine if H(2)S is a major physiological EDHF., Methods and Results: We now show that H(2)S is a major EDHF because in blood vessels of CSE-deleted mice, hyperpolarization is virtually abolished. H(2)S acts by covalently modifying (sulfhydrating) the ATP-sensitive potassium channel, as mutating the site of sulfhydration prevents H(2)S-elicited hyperpolarization. The endothelial intermediate conductance (IK(Ca)) and small conductance (SK(Ca)) potassium channels mediate in part the effects of H(2)S, as selective IK(Ca) and SK(Ca) channel inhibitors, charybdotoxin and apamin, inhibit glibenclamide-insensitive, H(2)S-induced vasorelaxation., Conclusions: H(2)S is a major EDHF that causes vascular endothelial and smooth muscle cell hyperpolarization and vasorelaxation by activating the ATP-sensitive, intermediate conductance and small conductance potassium channels through cysteine S-sulfhydration. Because EDHF activity is a principal determinant of vasorelaxation in numerous vascular beds, drugs influencing H(2)S biosynthesis offer therapeutic potential.

Objective: Recent studies have demonstrated that hydrogen sulfide (H(2)S) is produced within the vessel wall from L-cysteine regulating several aspects of vascular homeostasis. H(2)S generated from cystathione γ-lyase (CSE) contributes to vascular tone; however, the molecular mechanisms underlying the vasorelaxing effects of H(2)S are still under investigation., Methods and Results: Using isolated aortic rings, we observed that addition of L-cysteine led to a concentration-dependent relaxation that was prevented by the CSE inhibitors DL-propargylglyicine (PAG) and β-cyano-l-alanine (BCA). Moreover, incubation with PAG or BCA resulted in a rightward shift in sodium nitroprusside-and isoproterenol-induced relaxation. Aortic tissues exposed to PAG or BCA contained lower levels of cGMP, exposure of cells to exogenous H(2)S or overexpression of CSE raised cGMP concentration. RNA silencing of CSE expression reduced intracellular cGMP levels confirming a positive role for endogenous H(2)S on cGMP accumulation. The ability of H(2)S to enhance cGMP levels was greatly reduced by the nonselective phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. Finally, addition of H(2)S to a cell-free system inhibited both cGMP and cAMP breakdown., Conclusions: These findings provide direct evidence that H(2)S acts as an endogenous inhibitor of phosphodiesterase activity and reinforce the notion that this gasotransmitter could be therapeutically exploited.

Background: Hydrogen sulfide (H(2)S) is an endogenous signaling molecule with potent cytoprotective effects. The present study evaluated the therapeutic potential of H(2)S in murine models of heart failure., Methods and Results: Heart failure was induced by subjecting mice either to permanent ligation of the left coronary artery for 4 weeks or to 60 minutes of left coronary artery occlusion followed by reperfusion for 4 weeks. Transgenic mice with cardiac-restricted overexpression of the H(2)S-generating enzyme cystathione gamma-lyase (alphaMHC-CGL-Tg(+)) displayed a clear protection against left ventricular structural and functional impairment as assessed by echocardiography in response to ischemia-induced heart failure, as well as improved survival in response to permanent myocardial ischemia. Exogenous H(2)S therapy (Na(2)S; 100 microg/kg) administered at the time of reperfusion (intracardiac) and then daily (intravenous) for the first 7 days after myocardial ischemia also protected against the structural and functional deterioration of the left ventricle by attenuating oxidative stress and mitochondrial dysfunction. Additional experiments aimed at elucidating some of the protective mechanisms of H(2)S therapy found that 7 days of H(2)S therapy increased the phosphorylation of Akt and increased the nuclear localization of 2 transcription factors, nuclear respiratory factor 1 and nuclear factor-E2-related factor (Nrf2), that are involved in increasing the levels of endogenous antioxidants, attenuating apoptosis, and increasing mitochondrial biogenesis., Conclusions: The results of the present study suggest that either the administration of exogenous H(2)S or the modulation of endogenous H(2)S production may be of therapeutic benefit in the treatment of ischemia-induced heart failure.

In this study, we determined the cardioprotective effects of S-propargyl-cysteine (SPRC), a structural analog of S-allylcysteine (SAC), using in vivo models of acute myocardial infarction (MI) and in vitro hypoxic cardiomyocytes models. MI was created in rats by ligating the left anterior descending coronary artery. Plasma enzymes levels and cystathionine-gamma-lyase (CSE) activities were determined. Primary cultures of newborn rats' cardiomyocytes were injured by hypoxia for 6 h. Cell viabilities were measured with the thiazolyl blue assay. RT-PCR and western blot analysis revealed the expression of CSE in both models. The protective effects of SPRC were associated with an observed reduction in infarct size (20.8 +/- 2.4% vs. 36.0 +/- 1.3%), decreased plasma enzymes levels and reduced malondialdehyde levels when compared to the MI vehicle group (P < 0.05); cardiac function was also improved. SPRC increased CSE activity and plasma H2S concentration by 1.6-fold and 1.3-fold, respectively, in MI rats. Decreased cell viability (64.5 +/- 5.4%) in hypoxic cardiomyocytes could be rescued with use of SPRC (81.0 +/- 3.1%). Similarly, mRNA and protein expression of CSE were upregulated in the SPRC group. Treatment with the CSE inhibitor propargylglycine abolished the protective effects of SPRC. Our study provides novel evidence that SPRC is protective in myocardial infarctions via a H2S-related pathway.

Objective: We explored the effect of hydrogen sulfide (H(2)S) on atherosclerotic progression, particularly on intracellular adhesion molecule-1 (ICAM-1) in apolipoprotein-E knockout (apoE(-/-)) mice and human umbilical vein endothelial cells (HUVECs)., Methods and Results: ApoE(-/-) mice were treated with sodium hydrosulfide (NaHS) or DL-propargylglycine (PPG); HUVECs were pretreated with NaHS. Compared with control mice, apoE(-/-) mice showed decreased plasma H(2)S level and aortic H(2)S production but increased plasma ICAM-1 and aortic ICAM-1 protein and mRNA. Compared with apoE(-/-) mice, apoE(-/-)+NaHS mice showed increased plasma H(2)S level, but decreased size of atherosclerotic plaque and plasma and aortic ICAM-1 levels, whereas apoE(-/-)+PPG mice showed decreased plasma H(2)S level but enlarged plaque size and increased plasma and aortic ICAM-1 levels. NaHS suppressed ICAM-1 expression in tumor necrosis factor (TNF)-alpha-treated HUVECs. NaHS inhibited IkappaB degradation and NF-kappaB nuclear translocation in HUVECs treated with TNF-alpha., Conclusions: The vascular CSE/H(2)S pathway was disturbed in apoE(-/-) mice. H(2)S exerted an antiatherogenic effect and inhibited ICAM-1 expression in apoE(-/-) mice. H(2)S inhibited ICAM-1 expression in TNF-alpha-induced HUVECs via the NF-kappaB pathway.