Yi n Zhu

Hydrogen sulfide is a novel mediator of lipopolysaccharide-induced inflammation in the mouse

Hydrogen sulfide (H2S) is synthesized in the body from l‐cysteine by several enzymes including cystathionine‐γ‐lyase (CSE). To date, there is little information about the potential role of H2S in inflammation. We have now investigated the part played by H2S in endotoxin‐induced inflammation in the mouse. E. coli lipopolysaccharide (LPS) administration produced a dose (10 and 20 mg/kg ip)‐ and time (6 and 24 h)‐dependent increase in plasma H2S concentration. LPS (10 mg/kg ip, 6 h) increased plasma H2S concentration from 34.1 ± 0.7 µM to 40.9 ± 0.6 µM (n=6, P<0.05) while H2S formation from added l‐cysteine was increased in both liver and kidney. CSE gene expression was also increased in both liver (94.2±2.7%, n=6, P<0.05) and kidney (77.5±3.2%, n=6, P<0.05). LPS injection also elevated lung (148.2±2.6%, n=6, P<0.05) and kidney (78.8±8.2%, n=6, P<0.05) myeloperoxidase (MPO, a marker of tissue neutrophil infiltration) activity alongside histological evidence of lung, liver, and kidney tissue inflammatory damage. Plasma nitrate/nitrite (NOx) concentration was additionally elevated in a time‐ and dose‐dependent manner in LPS‐injected animals. To examine directly the possible proinflammatory effect of H2S, mice were administered sodium hydrosulfide (H2S donor drug, 14 µmol/kg ip) that resulted in marked histological signs of lung inflammation, increased lung and liver MPO activity, and raised plasma TNF‐α concentration (4.6±1.4 ng/ml, n=6). In contrast, dl‐propargylglycine (CSE inhibitor, 50 mg/kg ip), exhibited marked anti‐inflammatory activity as evidenced by reduced lung and liver MPO activity, and ameliorated lung and liver tissue damage. In separate experiments, we also detected significantly higher (150.5±43.7 µM c.f. 43.8±5.1 µM, n=5, P<0.05) plasma H2S levels in humans with septic shock. These findings suggest that H2S exhibits proinflammatory activity in endotoxic shock and suggest a new approach to the development of novel drugs for this condition.

Bioactive S-alk(en)yl cysteine sulfoxide metabolites in the genus Allium: the chemistry of potential therapeutic agents

S-Alk(en)yl cysteine sulfoxides are odourless, non-protein sulfur amino acids typically found in members of the family Alliaceae and are the precursors to the lachrymatory and flavour compounds found in the agronomically important genus Allium. Traditionally, Allium species, particularly the onion (Allium cepa) and garlic (A. sativum), have been used for centuries in European, Asian and American folk medicines for the treatment of numerous human pathologies, however it is only recently that any significant progress has been made in determining their mechanisms of action. Indeed, our understanding of the role of Allium species in human health undoubtedly comes from the combination of several academic disciplines including botany, biochemistry and nutrition. During tissue damage, S-alk(en)yl cysteine sulfoxides are converted to their respective thiosulfinates or propanethial-S-oxide by the action of the enzyme alliinase (EC 4.4.1.4). Depending on the Allium species, and under differing conditions, thiosulfinates can decompose to form additional sulfur constituents including diallyl, methyl allyl, and diethyl mono-, di-, tri-, tetra-, penta-, and hexasulfides, the vinyldithiins and (E)- and (Z)-ajoene. Recent reports have shown onion and garlic extracts, along with several principal sulfur constituents, can induce phase II detoxification enzymes like glutathione-S-transferases (EC 2.5.1.18) and quinone reductase (QR) NAD(P)H: (quinine acceptor) oxidoreductase (EC 1.6.99.2) in mammalian tissues, as well as also influencing cell cycle arrest and apoptosis in numerous in vitro cancer cell models. Moreover, studies are also beginning to highlight a role of Allium-derived sulfur compounds in cardiovascular protection. In this review, we discuss the chemical diversity of S-alk(en)yl cysteine sulfoxide metabolites in the context of their biochemical and pharmacological mechanisms.

Oxidative Stress: Apoptosis in Neuronal Injury

Apoptosis has been well documented to play a significant role in cell loss during neurodegenerative disorders, such as stroke, Parkinson disease, and Alzheimers disease. In addition, reactive oxygen species (ROS) has been implicated in the cellular damage during these neurodegenerative disorders. These ROS can react with cellular macromolecular through oxidation and cause the cells undergo necrosis or apoptosis. The control of the redox environment of the cell provides addition regulation in the signal transduction pathways which are redox sensitive. Recently, many researches focus on the relationship between apoptosis and oxidative stress. However, till now, there is no clear and defined mechanisms that how oxidative stress could contribute to the apoptosis. This review hopes to make clear that generation of ROS during brain injury, particularly in ischemic stroke and Alzheimers Disease, and the fact that oxidative state plays a key role in the regulation and control of the cell survival and cell death through its interaction with cellular macromolecules and signal transduction pathway, and ultimately helps in developing an unique therapy for the treatment of these neurodegenerative disorders.

Comparison of cardioprotective effects using ramipril and DanShen for the treatment of acute myocardial infarction in rats.

In the present study, we compared cardioprotective effects of DanShen (an extract from Salvia miltiorrhiza) and the angiotensin-converting enzyme inhibitor, ramipril, in rats. With both treatment regimens, DanShen- and ramipril similar effects were observed: (1) a higher survival rate, (2) a significant reduction of infarct size, (3) significantly lower ratios of heart weight to the body weight as well as the left and right ventricular weights to body weight. DanShen showed some unique effects in the following aspects: (1) higher activities of antioxidant defense enzymes such as superoxide dismutase (SOD), catalase (CAT), glutatione perioxidase (GSH-Px) and glutathione S-transferase (GST) in the liver of rats with acute myocardial infarction (AMI), (2) lower myocardial and hepatic TBARS values; (3) augmented VEGF mRNA expressions in the non-ischemic parts of rat hearts with AMI. These results were consistent with the findings of a slight increase in myocardial capillary density and the special distribution pattern of coronary blood vessels in DanShen-treated rats.

VEGFR2 Functions As an H2S-Targeting Receptor Protein Kinase with Its Novel Cys1045–Cys1024 Disulfide Bond Serving As a Specific Molecular Switch for Hydrogen Sulfide Actions in Vascular Endothelial Cells

AIMS The potential receptor for hydrogen sulfide (H2S) remains unknown. RESULTS H2S could directly activate vascular endothelial growth factor receptor 2 (VEGFR2) and that a small interfering RNA (siRNA)-mediated knockdown of VEGFR2 inhibited H2S-induced migration of human vascular endothelial cells. H2S promoted angiogenesis in Matrigel plug assay in mice and this effect was attenuated by a VEGF receptor inhibitor. Using tandem mass spectrometry (MS), we identified a new disulfide complex located between Cys1045 and Cys1024 within VEGFR2 that was labile to H2S-mediated modification. Kinase activity of the mutant VEGFR2 (C1045A) devoid of the Cys1045-Cys1024 disulfide bond was significantly higher than wild-type VEGFR2. Transfection with vectors expressing VEGFR2 (C1045A) caused a significant increase in cell migration, while the migration-promoting effect of H2S disappeared in the cells transfected with VEGFR2 (C1045A). Therefore, the Cys1045-Cys1024 disulfide bond serves as an intrinsic inhibitory motif and functions as a molecular switch for H2S. The formation of the Cys1045-Cys1024 disulfide bond disrupted the integrity of the active conformation of VEGFR2. Breaking the Cys1045-Cys1024 disulfide bond recovered the active conformation of VEGFR2. This motif was prone to a nucleophilic attack by H2S via an interaction of their frontier molecular orbitals. siRNA-mediated knockdown of cystathionine γ-lyase attenuated migration of vascular endothelial cells induced by VEGF or moderate hypoxia. INNOVATION AND CONCLUSION The study provides the first piece of evidence of a molecular switch in H2S-targeting receptor protein kinase in H2S-induced angiogenesis and that may be applicable to additional kinases containing functionally important disulfide bonds in mediating various H2S actions.

A Boron-dipyrromethene-Based Fluorescent Probe for Colorimetric and Ratiometric Detection of Sulfite

BODIPY-Le, a colorimetric and ratiometric fluorescent probe based on boron-dipyrromethene for selective detection sulfite ion, was investigated. Boron-dipyrromethene levulinyl ester (BODIPY-Le) is composed of an indole-based BODIPY dye and the levulinyl protective group, which could be easily and selectively deprotected by sulfites. As a result, the absorption and emission spectra show a dramatic red shift, and the development of a colorimetric and ratiometric fluorescent sulfite probe could be achieved. Besides, BODIPY-Le also exhibited prominent turn-on or turn-off type fluorogenic signaling toward sulfite ions once excited at 510 and 620 nm, respectively.

Hydrogen Sulfide Protects HUVECs against Hydrogen Peroxide Induced Mitochondrial Dysfunction and Oxidative Stress

Background Hydrogen sulfide (H2S) has been shown to have cytoprotective effects in models of hypertension, ischemia/reperfusion and Alzheimers disease. However, little is known about its effects or mechanisms of action in atherosclerosis. Therefore, in the current study we evaluated the pharmacological effects of H2S on antioxidant defenses and mitochondria protection against hydrogen peroxide (H2O2) induced endothelial cells damage. Methodology and Principal Findings H2S, at non-cytotoxic levels, exerts a concentration dependent protective effect in human umbilical vein endothelial cells (HUVECs) exposed to H2O2. Analysis of ATP synthesis, mitochondrial membrane potential (ΔΨm) and cytochrome c release from mitochondria indicated that mitochondrial function was preserved by pretreatment with H2S. In contrast, in H2O2 exposed endothelial cells mitochondria appeared swollen or ruptured. In additional experiments, H2S was also found to preserve the activities and protein expressions levels of the antioxidants enzymes, superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in H2O2 exposed cells. ROS and lipid peroxidation, as assessed by measuring H2DCFDA, dihydroethidium (DHE), diphenyl-l-pyrenylphosphine (DPPP) and malonaldehyde (MDA) levels, were also inhibited by H2S treatment. Interestingly, in the current model, D, L-propargylglycine (PAG), a selective inhibitor of cystathionine γ-lyase (CSE), abolished the protective effects of H2S donors. Innovation This study is the first to show that H2S can inhibit H2O2 mediated mitochondrial dysfunction in human endothelial cells by preserving antioxidant defences. Significance H2S may protect against atherosclerosis by preventing H2O2 induced injury to endothelial cells. These effects appear to be mediated via the preservation of mitochondrial function and by reducing the deleterious effects of oxidative stress.

Hydrogen Sulfide Attenuated Tumor Necrosis Factor-α-Induced Inflammatory Signaling and Dysfunction in Vascular Endothelial Cells

Background Hydrogen sulfide (H2S), the third physiologically relevant gaseous molecule, is recognized increasingly as an anti-inflammatory mediator in various inflammatory conditions. Herein, we explored the effects and mechanisms of sodium hydrosulfide (NaHS, a H2S donor) on tumor necrosis factor (TNF)-α-induced human umbilical vein endothelial cells (HUVEC) dysfunction. Methodology and Principal Findings Application of NaHS concentration-dependently suppressed TNF-α-induced mRNA and proteins expressions of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), mRNA expression of P-selectin and E-selectin as well as U937 monocytes adhesion to HUVEC. Western blot analysis revealed that the expression of the cytoprotective enzyme, heme oxygenase-1 (HO-1), was induced and coincident with the anti-inflammatory action of NaHS. Furthermore, TNF-α-induced NF-κB activation assessed by IκBα degradation and p65 phosphorylation and nuclear translocation and ROS production were diminished in cells subjected to treatment with NaHS. Significance H2S can exert an anti-inflammatory effect in endothelial cells through a mechanism that involves the up-regulation of HO-1.

Protective Effects of Cysteine Analogues on Acute Myocardial Ischemia: Novel Modulators of Endogenous H2S Production

The current study was designed to evaluate the pharmacologic effects of three novel cysteine-containing compounds: S-propyl-l-cysteine (SPC), S-allyl-l-cysteine (SAC), and S-propargyl-l-cysteine (SPRC) on H(2)S production and antioxidant defenses in an acute myocardial infarction (MI) rat model. The enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as glutathione redox status and malonaldehyde (MDA) content, also were determined. All three compounds were found to preserve SOD and GPx activities and also tissue GSH levels while reducing the formation of the lipid peroxidation product MDA in ventricular tissues. With immunfluorescence assays, we observed the expression of CSE and Mn-SOD. The morphologic changes of the cardiac cells are seen with both light and electron microscopy. The corresponding pathologic alterations were characterized mainly as loss of adherence between cardiac myocytes and swollen or ruptured mitochondria at the ultrastructural level. Propargylglycine, a selective inhibitor of CSE, abolished the protective effects of each compound used in the current model. Our study provides novel evidence that SPC, SAC, and SPRC have cardioprotective effects in MI by reducing the deleterious effects of oxidative stress by modulating the endogenous levels of H(2)S and preserving the activities of antioxidant defensive enzymes like SOD.

The role of urotensin II in cardiovascular and renal physiology and diseases

1 Urotensin II (U‐II) is a cyclic neuropeptide that was first isolated from teleost fish some 35 years ago. Mammalian U‐II is a powerful vasoconstrictor with a potency greater than that of endothelin‐1. 2 Nevertheless, unlike endothelin‐1, which constricts all or nearly all vascular beds, the vasoactive effects of U‐II are reported to be dependent both on the species and on the regional vascular bed examined. Typical regional variability occurs in the rat in which vasoconstriction to U‐II is most robust in thoracic aorta proximal to the aortic arch and decreases gradually towards the distal peripheral arteries. As small peripheral arteries but not larger arteries such as the aorta play a major role in regulating peripheral resistance and consequent blood pressure as well as workload on the heart, doubts have been raised concerning the importance of this peptide in cardiovascular physiology. Moreover, an interaction between U‐II and other endogenous vasoactive molecules may add a level of complexity to the vascular actions of U‐II. 3 On the other hand, recent experimental and clinical studies have revealed increased expression of U‐II and urotensin receptor (UT receptor) in animals with experimentally induced myocardial infarction, heart failure, and in patients with hypertension, atherosclerosis, and diabetic nephropathy, which suggests a potential role for U‐II in both cardiovascular and renal diseases. A series of peptidic and nonpeptidic UT receptor ligands have been shown to be effective in antagonizing the effects of U‐II in the cardiorenal system. 4 This article aims to review recent advances in our understanding of the physiology and pathophysiology of U‐II with particular references to its role in cardiovascular health and disease.