scholarly journals Inhibition by Polyphenolic Phytochemicals and Sulfurous Compounds of the Formation of 8-Chloroguanosine Mediated by Hypochlorous Acid, Human Myeloperoxidase, and Activated Human Neutrophils

2012 ◽  
Vol 76 (12) ◽  
pp. 2208-2213 ◽  
Author(s):  
Toshiki NAKANO ◽  
Mitsuharu MASUDA ◽  
Toshinori SUZUKI ◽  
Hiroshi OHSHIMA
Keyword(s):  
Hypochlorous Acid ◽  
Human Neutrophils ◽  
Sulfurous Compounds

In vitro effect of elastase and cathepsin G from human neutrophils on creatine kinase and lactate dehydrogenase isoenzymes

1993 ◽  
Vol 39 (6) ◽  
pp. 986-992
Author(s):  
J A Stark ◽  
A R Henderson
Keyword(s):  
Creatine Kinase ◽  
Lactate Dehydrogenase ◽  
Hypochlorous Acid ◽  
Proteolytic Enzymes ◽  
Sodium Dodecyl ◽  
Cathepsin G ◽  
Human Neutrophils ◽  
Sample Treatment ◽  
Vitro Effect

Abstract The polymorphonuclear granulocyte, or neutrophil, has been implicated as a mediator of tissue-destructive events because it releases the preformed proteolytic enzymes elastase and cathepsin G, and, as a result of myeloperoxidase action, hypochlorous acid. We show that elastase inactivates and fragments creatine kinase isoenzymes CK-2 and CK-3, and, to a lesser extent, lactate dehydrogenase (LD) isoenzyme LD-1, whereas cathepsin G acts only on CK-2. Both neutrophil enzymes act on LD-3. The course of inactivation was followed by measuring the loss of catalytic activity at 37 degrees C. The evidence for fragmentation was obtained by gel filtration; electrophoresis after sample treatment with sodium dodecyl sulfate and 2-mercaptoethanol was less satisfactory for this purpose. Hypochlorous acid inactivates CK activity by about 75% at concentrations as low as 8 mumol/L and totally at concentrations > 140 mumol/L, whereas LD activity is not affected until concentrations exceed 200 mumol/L. After a myocardial infarction, the number of neutrophils increases; they are triggered and concentrate around damaged myocardial tissue. Our data suggest that neutrophils may inactivate and fragment "cardiac" enzymes released from such damaged tissue.

Serotonin as a physiological substrate for myeloperoxidase and its superoxide-dependent oxidation to cytotoxic tryptamine-4,5-dione

2009 ◽  
Vol 425 (1) ◽  
pp. 285-293 ◽  
Author(s):  
Valdecir F. Ximenes ◽  
Ghassan J. Maghzal ◽  
Rufus Turner ◽  
Yoji Kato ◽  
Christine C. Winterbourn ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Nadph Oxidase ◽  
Tissue Damage ◽  
Acid Production ◽  
Hypochlorous Acid ◽  
Human Neutrophils ◽  
Toxic Metabolite ◽  
Inflammatory Processes ◽  
Physiological Substrates ◽  
Inflammatory Tissue

During inflammatory events, neutrophils and platelets interact to release a variety of mediators. Neutrophils generate superoxide and hydrogen peroxide, and also discharge the haem enzyme myeloperoxidase. Among numerous other mediators, platelets liberate serotonin (5-hydroxytryptamine), which is a classical neurotransmitter and vasoactive amine that has significant effects on inflammation and immunity. In the present study, we show that serotonin is a favoured substrate for myeloperoxidase because other physiological substrates for this enzyme, including chloride, did not affect its rate of oxidation. At low micromolar concentrations, serotonin enhanced hypochlorous acid production by both purified myeloperoxidase and neutrophils. At higher concentrations, it almost completely blocked the formation of hypochlorous acid. Serotonin was oxidized to a dimer by myeloperoxidase and hydrogen peroxide. It was also converted into tryptamine-4,5-dione, especially in the presence of superoxide. This toxic quinone was produced by stimulated neutrophils in a reaction that required myeloperoxidase. In plasma, stimulated human neutrophils oxidized serotonin to its dimer using the NADPH oxidase and myeloperoxidase. We propose that myeloperoxidase will oxidize serotonin at sites of inflammation. In doing so, it will impair its physiological functions and generate a toxic metabolite that will exacerbate inflammatory tissue damage. Consequently, oxidation of serotonin by myeloperoxidase may profoundly influence inflammatory processes.

Chalcones as Scavengers of HOCl and Inhibitors of Oxidative Burst: Structure-Activity Relationship Studies

2020 ◽  
Vol 17 ◽  
Author(s):  
Thaise Martins ◽  
Vera L.M. Silva ◽  
Artur M.S. Silva ◽  
José L.F.C. Lima ◽  
Eduarda Fernandes ◽  
...  
Keyword(s):  
Oxidative Burst ◽  
Hypochlorous Acid ◽  
Biological Activities ◽  
Chemical Diversity ◽  
Human Neutrophils ◽  
Aromatic Rings ◽  
Structure Activity ◽  
Antioxidant Agents ◽  
Ic50 Values ◽  
Anti Inflammatory

Aims: Evaluate the ability of chalcones to scavenge hypochlorous acid (HOCl) and modulate oxidative burst. Background: The chemistry of chalcones has long been a matter of interest to the scientific community due to the phenolic groups often present and to the various replaceable hydrogens that allow the formation of a broad number of derivatives. Due to this chemical diversity, several biological activities have been attributed to chalcones, namely anti-diabetic, anti-inflammatory and antioxidant. Objectives: Evaluate the ability of a panel of 34 structurally related chalcones to scavenge HOCl and/or suppress its produc-tion through the inhibition of human neutrophils’ oxidative burst, followed by the establishment of the respective structure-activity relationships. Methods: The ability of chalcones to scavenge HOCl was evaluated by fluorimetric detection of the inhibition of dihydro-rhodamine 123 oxidation. The ability of chalcones to inhibit neutrophils’ oxidative burst was evaluated by chemiluminomet-ric detection of the inhibition of luminol oxidation. Results: It was observed that the ability to scavenge HOCl depends on the position and number of hydroxy groups on both aromatic rings. Chalcone 5b was the most active with an IC50 value of 1.0 ± 0.1 μM. The ability to inhibit neutrophils’ oxi-dative burst depends on the presence of a 2’-hydroxy group on A-ring and on other substituents groups, e.g. methoxy, hy-droxy, nitro and/or chlorine atom(s) at C-2, C-3 and/or C-4 on B-ring, as in chalcones 2d, 2f, 2j, 2i, 4b, 2n and 1d, which were the most actives with IC50 values ranging from 0.61 ± 0.02 μM to 1.7 ± 0.2 μM. Conclusion: The studied chalcones showed high activity at a low micromolar range, indicating their potential as antioxidant agents and to be used as a molecular structural scaffold for the design of new anti-inflammatory compounds.

scholarly journals Cyanate-mediated inhibition of neutrophil myeloperoxidase activity

1997 ◽  
Vol 326 (1) ◽  
pp. 159-166 ◽  
Author(s):  
Mingwei QIAN ◽  
John W. EATON ◽  
Simon P. WOLFF
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Hypochlorous Acid ◽  
The Body ◽  
Human Neutrophils ◽  
Myeloperoxidase Activity ◽  
Alternative Substrate ◽  
Bacterial Killing ◽  
Susceptibility To Infection ◽  
Enhanced Chemiluminescence

Cyanate (CNO-) forms spontaneously in solutions containing urea, and is present in urine and the body fluids of uraemic patients. We have explored the possibility that CNO- might be one of the unknown substances responsible for the reported impairment, by urine and uraemic plasma, of neutrophil oxidative metabolism (especially as measured by luminol-enhanced chemiluminescence). Luminol-enhanced chemiluminescence generated by human neutrophils derives predominantly from the activity of myeloperoxidase (MPO) which produces hypochlorous acid from H2O2 and Cl-. We hypothesized that CNO- (which resembles the ‘pseudohalide’ thiocyanate, an alternative substrate for MPO) might somehow interfere with the activity of MPO. In support of this, we find: (i) CNO- inhibits both peroxidative and halogenating activities of MPO and also inhibits the enzyme within intact human neutrophils; (ii) the inhibition is H2O2-dependent, irreversible, accompanied by covalent addition of [14C]CNO- (or a carbon-containing fragment thereof) to the enzyme; (iii) CNO- also inhibits Cl-/H2O2/MPO-mediated bacterial killing. Impairment of this arm of neutrophil bactericidal activity by CNO- formed from urea may be one factor in the risk of urinary-tract infection associated with urinary stasis and perhaps in the generalized increase in susceptibility to infection in uraemic patients.

scholarly journals Chlorination of Guanosine and Other Nucleosides by Hypochlorous Acid and Myeloperoxidase of Activated Human Neutrophils

2001 ◽  
Vol 276 (44) ◽  
pp. 40486-40496 ◽  
Author(s):  
Mitsuharu Masuda ◽  
Toshinori Suzuki ◽  
Marlin D. Friesen ◽  
Jean-Luc Ravanat ◽  
Jean Cadet ◽  
...  
Keyword(s):  
Hypochlorous Acid ◽  
Human Neutrophils

Neutrophils from Cystic Fibrosis Patients Are Defective in Killing of Phagocytosed Pseudomonas aeruginosa.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1648-1648
Author(s):  
Guoshun Wang ◽  
Vincent G. Valentine ◽  
Nicholas A. Lanson ◽  
Kevin Leidal ◽  
Qiang Zhang ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Chloride Channel ◽  
Hypochlorous Acid ◽  
Bacterial Load ◽  
Clinical Manifestations ◽  
Human Neutrophils ◽  
Published Data ◽  
Bacterial Killing

Abstract Cystic fibrosis (CF), the most common genetic disease in Caucasians, is caused by mutations of the gene encoding the CF transmembrane conductance regulator (CFTR), a cAMP-regulated chloride channel. CF has long been recognized as an epithelial disease whose most severe complications often occur in the lung. The clinical manifestations include persistent bacterial infection, prominent neutrophil infiltration and small airway obstruction. Even though dramatic advances have been made towards understanding of CF pathogenesis, the link between the CFTR chloride channel defect and a clinical defect in bacterial eradication has not been fully established. Our published data demonstrated that CFTR is expressed in human neutrophils and their phagolysosomes. CF neutrophils are defective in the chlorination of phagocytosed Pseudomonas aeruginosa (PAO1), indicating defective intraphagolysosomal hypochlorous acid (HOCl) production. In the current report, we assessed the bacterial killing abilities of neutrophils from CF and normal individuals. Percoll-purified peripheral blood neutrophils were incubated with opsonized PAO1 at a ratio of 1:1 or 1:50. To define the role of chloride in the killing process, two different Ringer’s buffers with either 0 mM chloride or 135 mM chloride were exploited. At various time points (0, 15, 30 and 60 minutes) after incubation of neutrophils with bacteria, samples were aliquoted to assay for viable bacteria. After correction for bacterial growth over the experimental period, the bacterial viability at each time point relative to that of the initial value was obtained. Two-way ANOVA tests indicated that CF neutrophils had a significantly lower initial rate of killing of PAO1 than that in normal controls. This defect is more pronounced under the condition of high bacterial load and low extracellular chloride. Surprisingly, the low extracellular chloride significantly affected neutrophil-mediated bacterial killing even for the normal neutrophils, suggesting the dependence of this ion in the killing process. Our data provide evidence to suggest the potential role of CFTR in supplying intraphagolysosomal chloride to produce hypochlorous acid (HOCl), an oxidant essential for the killing of HOCl-sensitive bacteria.

Singlet Oxygen Is Essential for Neutrophil Extracellular Trap Formation,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3209-3209 ◽  
Author(s):  
Yoko Nishinaka ◽  
Makiko Morita ◽  
Toshiyuki Arai ◽  
Souichi Adachi ◽  
Akifumi Takaori-Kondo ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Singlet Oxygen ◽  
Host Defense ◽  
Hypochlorous Acid ◽  
Conflicts Of Interest ◽  
Human Neutrophils ◽  
Specific Method ◽  
Free System ◽  
Fluorescence Confocal Microscopy ◽  
A Cell

Abstract Abstract 3209 Neutrophil extracellular traps (NETs), which capture microbes in extracellular structures consisting of DNA fibers and antimicrobial granule proteins, are pivotal for innate host defense, but the mechanism of NET formation remains unclear. Previous observation in neutrophils of chronic granulomatous disease (CGD) patients, which defect NADPH oxidase (Nox) and fail to produce reactive oxygen species (ROS), demonstrated that ROS are important for NET formation. However, the active species were not identified. Neutrophils first generate superoxide by Nox activation, and this superoxide is converted to hydrogen peroxide (H2O2) by superoxide dismutase. Then, hypochlorous acid is produced from H2O2 by myeloperoxidase (MPO), and reacts with H2O2 to form singlet oxygen (1O2). In the current study, we revealed that 1O2, one of the ROS, is essential for NET formation. We first examined the effect of 1O2 scavengers, a-phenyl-N-tert-butyl nitrone (PBN), 3-methyl-1-phenyl-2-pyrazolin-5-one (edaravone), or uric acid (UA), on Nox-dependent NET formation upon stimulation with phorbol myristate acetate (PMA). We previously showed that PBN and edaravone suppressed 1O2 release from activated neutrophils, but did not affect superoxide release (Sommani et al. J Pharmacol Sci 2007, Kawai et al. J Pharmacol Sci 2008). We also showed that PBN is a more specific 1O2 scavenger, since it neither affected MPO activity, nor reacted with hypochlorous acid (Kawai et al. J Pharmacol Sci 2008). UA is a well-known 1O2 scavenger. Human neutrophils were isolated from peripheral blood by sedimentation through two-step Percoll gradients. The CGD patient was a 24-year-old male with gp91-phox deficiency with a G-to-A point mutation at nucleotide 389 in exon 10. Healthy volunteers and the patient provided written informed consent for participation in an institutional review board-approved protocol at Kyoto University Hospital. NET formation by PMA was visualized by fluorescence microscopy with Sytox green, a cell-impermeable DNA dye, and scanning electron microscopy (SEM). NET formation was observed at 3 h after PMA stimulation (100 ng/ml) in healthy neutrophils. The treatment of edaravone (10 μM), PBN (4 mM), or UA (5 μg/ml) significantly suppressed NET formation, suggesting that 1O2 is involved in NET formation. In contrast, CGD neutrophils did not exhibit NET formation, which is consistent with previous reports (Fuchs et al. J Cell Biol 2007. Bianchi et al. Blood 2009). We next explored the direct effect 1O2 in NET formation. First, we detected 1O2 generation by the most specific method with irradiation of porfimer sodium (Photofrin) in a cell-free system, by direct analysis of near-infrared luminescence at 1270 nm using Raman spectroscopy. The treatment of edaravone (400 μM) almost completely suppressed the 1O2 spectrum, as well as azide (400 μM), a well-known 1O2 scavenger. Next, we observed the accumulation of Photofrin in neutrophils by fluorescence confocal microscopy after incubation with Photofrin (10 μg/ml) for 1 h. These findings indicated that 1O2 was generated in neutrophils by Photofrin with light irradiation. NET formation by Photofrin (10 μg/ml, for 1 h) with irradiation (LED lamp, λmax=660 nm, for 5 min) was analyzed by fluorescence microscopy and SEM. Interestingly, NET formation was observed in CGD neutrophils, as well as healthy neutrophils. It is noteworthy that CGD neutrophils did not exhibit Nox-dependent NET formation by PMA stimulation. This was suppressed by the treatment of 1O2 scavengers, edaravone (10 μM) or PBN (4 mM). These results suggested that 1O2 directly induced NET formation in both healthy and CGD neutrophils, independent of Nox activation. Taken together, our findings demonstrated that 1O2 is essential for NET formation, which supported a recent report that MPO is required for NET formation (Metzler et al. Blood, 2011), since 1O2 is generated downstream of MPO. The modulation of NET formation should be effective in the control of infectious or inflammatory disorders. From the current study, the suppression of 1O2 could be an optimal target for regulating NET formation, minimizing impairment of innate host defense. Disclosures: No relevant conflicts of interest to declare.

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