Previous studies have demonstrated that hydrogen sulfide (H 2 S) protects against multiple cardiovascular disease states in a similar manner as nitric oxide (NO). H 2 S therapy also has been shown to augment NO bioavailability and signaling. The purpose of this study was to investigate the impact of H 2 S deficiency on endothelial NO synthase (eNOS) function, NO production, and ischemia/reperfusion (I/R) injury. We found that mice lacking the H 2 S-producing enzyme cystathionine γ-lyase (CSE) exhibit elevated oxidative stress, dysfunctional eNOS, diminished NO levels, and exacerbated myocardial and hepatic I/R injury. In CSE KO mice, acute H 2 S therapy restored eNOS function and NO bioavailability and attenuated I/R injury. In addition, we found that H 2 S therapy fails to protect against I/R in eNOS phosphomutant mice (S1179A). Our results suggest that H 2 S-mediated cytoprotective signaling in the setting of I/R injury is dependent in large part on eNOS activation and NO generation.eNOS uncoupling | myocardial infarction | cystathionase | Cth | nitrite H ydrogen sulfide (H 2 S), historically known for its odorous smell and toxicity at high concentrations, has recently been classified as a physiological signaling molecule with robust cytoprotective actions in multiple organ systems (1-3). H 2 S is produced enzymatically in mammalian tissues by three different enzymes: cystathionine γ-lyase (CSE), cystathionine beta-synthase (CBS), and 3-mercatopyruvate sulfurtransferase (3-MST). CSE, involved in the cysteine biosynthesis pathway, coordinates with L-cystine to produce H 2 S within the vasculature and is known to regulate blood pressure, modulate cellular metabolism, promote angiogenesis, regulate ion channels, and mitigate fibrosis and inflammation (4). Endothelial nitric oxide synthase (eNOS) catalyzes the production of nitric oxide (NO) from L-arginine within the endothelium to regulate vascular tone via cGMP signaling in vascular smooth muscle, mitochondrial respiration, platelet function, inflammation, and angiogenesis. The biological profiles of H 2 S and NO are similar, and both molecules are known to protect cells against various injurious states that result in organ injury. Although H 2 S and NO are thought to modulate independent signaling pathways, there is limited evidence of cross-talk between these two molecules (5, 6).H 2 S therapeutics and endogenous overexpression of CSE have been shown to attenuate ischemia/reperfusion (I/R) injury (7,8). Similarly, NO therapy and eNOS gene overexpression are also protective in ischemic disease states (9). Given the potent antioxidant actions of H 2 S (10, 11) and the effects of exogenous H 2 S therapy on NO bioavailability (5, 8), we investigated the effects of genetic deletion of the cystathionase gene (Cth, i.e., CSE KO) on the regulation of eNOS function and NO bioavailability. ResultsSulfide Levels are Reduced in CSE KO Mice. Whole blood and heart specimens were collected from WT and CSE KO mice to measure H 2 S levels using a high-sensitivity gas chromato...

Background Trimethylamine N-oxide (TMAO), a gut microbe dependent metabolite of dietary choline and other trimethylamine containing nutrients, is both elevated in the circulation of patients suffering from heart failure (HF) and heralds worse overall prognosis. In animal studies, dietary choline or TMAO significantly accelerate atherosclerotic lesion development in ApoE deficient mice, and reduction in TMAO levels inhibits atherosclerosis development in the LDL receptor knockout mouse. Methods and Results C57BL6/J mice were fed either a control diet, a diet containing choline (1.2%) or a diet containing TMAO (0.12%) starting 3 weeks prior to surgical TAC. Mice were studied for 12 weeks following TAC. Cardiac function and left ventricular structure were monitored at 3-week intervals using echocardiography. Twelve weeks post-TAC myocardial tissues were collected to evaluate cardiac and vascular fibrosis, and blood samples were evaluated for cardiac BNP, choline, and TMAO levels. Pulmonary edema, cardiac enlargement, and left ventricular ejection fraction (LVEF) were significantly (p < 0.05, each) worse in mice fed either TMAO or choline supplemented diets compared to the control diet. In addition, myocardial fibrosis was also significantly greater (p < 0.01, each) in the TMAO and choline groups relative to controls. Conclusions Heart failure severity is significantly enhanced in mice fed diets supplemented in either choline or the gut microbe-dependent metabolite TMAO. The present results suggest that further studies are warranted examining whether gut microbiota and the dietary choline -> TMAO pathway contribute to increased heart failure susceptibility.

Hydrogen sulfide (H2S), known as an important cellular signaling molecule, plays critical roles in many physiological and/or pathological processes. Modulation of H2S levels could have tremendous therapeutic value. However, the study on H2S has been hindered due to the lack of controllable H2S releasing agents which could mimic the slow and moderate H2S release in vivo. In this work we report the design, synthesis and biological evaluation of a new class of controllable H2S donors. Twenty five donors were prepared and tested. Their structures were based on a perthiol template, which was suggested to involve in H2S biosynthesis. H2S release mechanism from these donors was studied and proved to be thiol-dependent. We also developed a series of cell-based assays to access their H2S related activities. H9c2 cardiac myocytes were used in these experiments. We tested lead donors’ cytotoxicity and confirmed their H2S production in cells. Finally we demonstrated that selected donors showed potent protective effects in an in vivo murine model of myocardial ischemia-reperfusion injury, through a H2S related mechanism.

BackgroundSporadic Creutzfeldt-Jakob disease is classified according to the genotype at polymorphic codon 129 (M or V) of the prion protein (PrP) gene and the type (1 or 2) of abnormal isoform of PrP (PrPSc) in the brain. The most complicated entity in the current classification system is MV2, since it shows wide phenotypic variations, i.e., MV2 cortical form (MV2C), MV2 with kuru plaques (MV2K), or a mixed form (MV2K + C). To resolve their complicated pathogenesis, we performed a comprehensive analysis of the three MV2 subgroups based on histopathological, molecular, and transmission properties.ResultsIn histopathological and molecular analyses, MV2C showed close similarity to MM2 cortical form (MM2C) and could be easily discriminated from the other MV2 subgroups. By contrast, MV2K and MV2K + C showed the same molecular type and the same transmission type, and the sole difference between MV2K and MV2K + C was the presence of cortical pathology characteristic of MV2C/MM2C. The remarkable molecular feature of MV2K or MV2K + C was a mixture of type 2 PrPSc and intermediate type PrPSc, which shows intermediate electrophoretic mobility between types 1 and 2 PrPSc. Modeling experiments using PrP-humanized mice indicated that MV2K contains a mixture of intermediate type PrPSc with the 129M genotype (Mi PrPSc) and type 2 PrPSc with the 129V genotype (V2 PrPSc) that originated from V2 PrPSc, whereas MV2C + K may also contain type 2 PrPSc with the 129M genotype and cortical pathology (M2C PrPSc) that lacks infectivity to the PrP-humanized mice in addition to Mi and V2 PrPSc.ConclusionsTaken together, the present study suggests that the phenotypic heterogeneity of MV2 stems from their different PrPSc origin(s).

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