1
|
Nayak M, Sonowal L, Pradhan L, Upadhyay A, Kamath P, Mukherjee S. Multifunctional (4-in-1) Therapeutic Applications of Nickel Thiocyanate Nanoparticles Impregnated Cotton Gauze as Antibacterial, Antibiofilm, Antioxidant and Wound Healing Agent. Chem Asian J 2024:e202400187. [PMID: 38665128 DOI: 10.1002/asia.202400187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/16/2024] [Indexed: 08/27/2024]
Abstract
The wounds, arises from accidents, burns, surgeries, diabetes, and trauma, can significantly impact well-being and present persistent clinical challenges. Ideal wound dressings should be flexible, stable, antibacterial, antioxidant and anti-inflammatory in nature, facilitating a scarless rapid wound healing. Initiatives were taken to create antibacterial cotton fabrics by incorporating agents like antibiotics and metallic nanoparticles. However, due to a lack of multifunctionality, these materials were not highly effective in causing scarless and rapid wound healing. In this article, nickel thiocyanate nanoparticle (NiSCN-NPs) impregnated cotton gauze wound dressing (NiSCN-CG) was developed. These nanoparticles were non-toxic to normal human cell lines till 1 mg/mL dose and did not cause skin irritation in the rat model. Further, NiSCN-NPs exhibited antimicrobial, antibiofilm and antioxidant activities confirmed using different in vitro experiments. In vivo wound healing studies in rat models using NiSCN-CG demonstrated rapid scarless wound healing. The nickel thiocyanate impregnated cotton gauze presents a novel approach in scarless wound healing, and as an antimicrobial agent, offering a promising solution for diverse wounds and infections in the future.
Collapse
Affiliation(s)
- Malay Nayak
- School of Biomedical Engineering, IIT (BHU), Varanasi, Varanasi, 221005, Uttar Pradesh, India
| | - Lidiya Sonowal
- School of Biomedical Engineering, IIT (BHU), Varanasi, Varanasi, 221005, Uttar Pradesh, India
| | - Lipi Pradhan
- School of Biomedical Engineering, IIT (BHU), Varanasi, Varanasi, 221005, Uttar Pradesh, India
| | - Anjali Upadhyay
- School of Biomedical Engineering, IIT (BHU), Varanasi, Varanasi, 221005, Uttar Pradesh, India
| | - Prajwal Kamath
- School of Biomedical Engineering, IIT (BHU), Varanasi, Varanasi, 221005, Uttar Pradesh, India
| | - Sudip Mukherjee
- School of Biomedical Engineering, IIT (BHU), Varanasi, Varanasi, 221005, Uttar Pradesh, India
| |
Collapse
|
2
|
Meredith JD, Gray MJ. Hypothiocyanite and host-microbe interactions. Mol Microbiol 2023; 119:302-311. [PMID: 36718113 DOI: 10.1111/mmi.15025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/30/2022] [Accepted: 01/03/2023] [Indexed: 02/01/2023]
Abstract
The pseudohypohalous acid hypothiocyanite/hypothiocyanous acid (OSCN- /HOSCN) has been known to play an antimicrobial role in mammalian immunity for decades. It is a potent oxidant that kills bacteria but is non-toxic to human cells. Produced from thiocyanate (SCN- ) and hydrogen peroxide (H2 O2 ) in a variety of body sites by peroxidase enzymes, HOSCN has been explored as an agent of food preservation, pathogen killing, and even improved toothpaste. However, despite the well-recognized antibacterial role HOSCN plays in host-pathogen interactions, little is known about how bacteria sense and respond to this oxidant. In this work, we will summarize what is known and unknown about HOSCN in innate immunity and recent advances in understanding the responses that both pathogenic and non-pathogenic bacteria mount against this antimicrobial agent, highlighting studies done with three model organisms, Escherichia coli, Streptococcus spp., and Pseudomonas aeruginosa.
Collapse
Affiliation(s)
- Julia D Meredith
- Department of Microbiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, USA
| | - Michael J Gray
- Department of Microbiology, University of Alabama at Birmingham Heersink School of Medicine, Birmingham, Alabama, USA
| |
Collapse
|
3
|
Flouda K, Gammelgaard B, Davies MJ, Hawkins CL. Modulation of hypochlorous acid (HOCl) induced damage to vascular smooth muscle cells by thiocyanate and selenium analogues. Redox Biol 2021; 41:101873. [PMID: 33550113 PMCID: PMC7868818 DOI: 10.1016/j.redox.2021.101873] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 02/08/2023] Open
Abstract
The production of hypochlorous acid (HOCl) by myeloperoxidase (MPO) plays a key role in immune defense, but also induces host tissue damage, particularly in chronic inflammatory pathologies, including atherosclerosis. This has sparked interest in the development of therapeutic approaches that decrease HOCl formation during chronic inflammation, including the use of alternative MPO substrates. Thiocyanate (SCN−) supplementation decreases HOCl production by favouring formation of hypothiocyanous acid (HOSCN), which is more selectively toxic to bacterial cells. Selenium-containing compounds are also attractive therapeutic agents as they react rapidly with HOCl and can be catalytically recycled. In this study, we examined the ability of SCN−, selenocyanate (SeCN−) and selenomethionine (SeMet) to modulate HOCl-induced damage to human coronary artery smooth muscle cells (HCASMC), which are critical to both normal vessel function and lesion formation in atherosclerosis. Addition of SCN− prevented HOCl-induced cell death, altered the pattern and extent of intracellular thiol oxidation, and decreased perturbations to calcium homeostasis and pro-inflammatory signaling. Protection was also observed with SeCN− and SeMet, though SeMet was less effective than SeCN− and SCN−. Amelioration of damage was detected with sub-stoichiometric ratios of the added compound to HOCl. The effects of SCN− are consistent with conversion of HOCl to HOSCN. Whilst SeCN− prevented HOCl-induced damage to a similar extent to SCN−, the resulting product hyposelenocyanous acid (HOSeCN), was more toxic to HCASMC than HOSCN. These results provide support for the use of SCN− and/or selenium analogues as scavengers, to decrease HOCl-induced cellular damage and HOCl production at inflammatory sites in atherosclerosis and other pathologies. HOCl induces extensive smooth muscle cell death and irreversible thiol oxidation. Addition of SCN− decreases the extent of HOCl-induced cell damage. SeCN− has similar protective effects to SCN− towards HOCl-induced cell damage. HOSeCN is less toxic than HOCl but more damaging than HOSCN. SeMet modulates HOCl-induced damage but less effectively than SCN− or SeCN−.
Collapse
Affiliation(s)
- Konstantina Flouda
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen, DK-2200, Denmark
| | - Bente Gammelgaard
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen, DK-2100, Denmark
| | - Michael J Davies
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen, DK-2200, Denmark
| | - Clare L Hawkins
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3B, Copenhagen, DK-2200, Denmark.
| |
Collapse
|
4
|
Guo C, Davies MJ, Hawkins CL. Role of thiocyanate in the modulation of myeloperoxidase-derived oxidant induced damage to macrophages. Redox Biol 2020; 36:101666. [PMID: 32781424 PMCID: PMC7417949 DOI: 10.1016/j.redox.2020.101666] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/20/2020] [Accepted: 07/28/2020] [Indexed: 12/13/2022] Open
Abstract
Myeloperoxidase (MPO) is a vital component of the innate immune system, which produces the potent oxidant hypochlorous acid (HOCl) to kill invading pathogens. However, an overproduction of HOCl during chronic inflammatory conditions causes damage to host cells, which promotes disease, including atherosclerosis. As such, there is increasing interest in the use of thiocyanate (SCN-) therapeutically to decrease inflammatory disease, as SCN- is the favoured substrate for MPO, and a potent competitive inhibitor of HOCl formation. Use of SCN- by MPO forms hypothiocyanous acid (HOSCN), which can be less damaging to mammalian cells. In this study, we examined the ability of SCN- to modulate damage to macrophages induced by HOCl, which is relevant to lesion formation in atherosclerosis. Addition of SCN- prevented HOCl-mediated cell death, altered the extent and nature of thiol oxidation and the phosphorylation of mitogen activated protein kinases. These changes were dependent on the concentration of SCN- and were observed in some cases, at a sub-stoichiometric ratio of SCN-: HOCl. Co-treatment with SCN- also modulated HOCl-induced perturbations in the expression of various antioxidant and inflammatory genes. In general, the data reflect the conversion of HOCl to HOSCN, which can induce reversible modifications that are repairable by cells. However, our data also highlight the ability of HOSCN to increase pro-inflammatory gene expression and cytokine/chemokine release, which may be relevant to the use of SCN- therapeutically in atherosclerosis. Overall, this study provides further insight into the cellular pathways by which SCN- could exert protective effects on supplementation to decrease the development of chronic inflammatory diseases, such as atherosclerosis.
Collapse
Affiliation(s)
- Chaorui Guo
- Department of Biomedical Sciences, University of Copenhagen, Panum, Blegdamsvej 3B, Copenhagen, DK-2200, Denmark
| | - Michael J Davies
- Department of Biomedical Sciences, University of Copenhagen, Panum, Blegdamsvej 3B, Copenhagen, DK-2200, Denmark
| | - Clare L Hawkins
- Department of Biomedical Sciences, University of Copenhagen, Panum, Blegdamsvej 3B, Copenhagen, DK-2200, Denmark.
| |
Collapse
|
5
|
Huang L, Xuan W, Sarna T, Hamblin MR. Comparison of thiocyanate and selenocyanate for potentiation of antimicrobial photodynamic therapy. JOURNAL OF BIOPHOTONICS 2019; 12:e201800092. [PMID: 29885019 PMCID: PMC6286685 DOI: 10.1002/jbio.201800092] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/07/2018] [Indexed: 06/08/2023]
Abstract
We have previously shown that antimicrobial photodynamic therapy (aPDT) mediated by different photosensitizers (PS) can be potentiated by a variety of inorganic salts. Potassium thiocyanate (KSCN) potentiated aPDT mediated by methylene blue (MB), while potassium selenocyanate (KSeCN) potentiated aPDT mediated by MB, Rose Bengal and the anionic porphyrin 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin dihydrochloride. However, the mechanisms of action that were proposed were fundamentally different. In the present study, we compare these two salts (KSCN and KSeCN) with different light-activated PS and different oxidative reactions for killing gram-positive and gram-negative bacteria. Overall KSeCN was more powerful than KSCN, and worked with a wider range of PS, while KSCN only worked with phenothiazinium salts. KSeCN produced killing when cells were added after light suggesting production of a semistable species called selenocyanogen (SeCN)2 . We tested three different oxidative reactions that can all potentially kill bacteria: lead tetraacetate (Pb[OAc]4 ); Fenton reagent (hydrogen peroxide [H2 O2 ] and ferrous sulfate) H2 O2 and horseradish peroxidase (HRP). In every case, KSeCN was substantially more effective (several logs) than KSCN in potentiating the bacterial killing. We conclude that (SeCN)2 is the mediator for aPDT using KSeCN, while sulfur trioxide radical anion is the mediator for KSCN using phenothiaziums. For H2 O2 /HRP with KSCN, hypothiocyanite is proposed to be the antibacterial agent in the literature, while hyposelenocyanite is said not to exist. Pb[OAc]4 is known to produce (SeCN)2 from KSeCN as well as the analogous (SCN)2 from KSCN. The mediators from Fenton reaction are unclear (pseudohalogen radical ions?) Both KSCN (which occurs naturally in the human body) and KSeCN may be clinically applicable.
Collapse
Affiliation(s)
- Liyi Huang
- Department of Infectious Diseases, First Affiliated
Hospital, Guangxi Medical University, Nanning, China
- Wellman Center for Photomedicine, Massachusetts General
Hospital, Boston, MA, USA
- Department of Dermatology, Harvard Medical School, Boston,
MA, USA
| | - Weijun Xuan
- Wellman Center for Photomedicine, Massachusetts General
Hospital, Boston, MA, USA
- Department of Dermatology, Harvard Medical School, Boston,
MA, USA
- Department of Otorhinolaryngology, Head and Neck Surgery,
First Clinical Medical College and Hospital, Guangxi University of Chinese Medicine,
Nanning, China
| | - Tadeusz Sarna
- Department of Biophysics, Faculty of Biochemistry,
Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Michael R Hamblin
- Wellman Center for Photomedicine, Massachusetts General
Hospital, Boston, MA, USA
- Department of Dermatology, Harvard Medical School, Boston,
MA, USA
- Harvard-MIT Division of Health Sciences and Technology,
Cambridge, MA, USA
| |
Collapse
|
6
|
Delporte C, Zouaoui Boudjeltia K, Furtmüller PG, Maki RA, Dieu M, Noyon C, Soudi M, Dufour D, Coremans C, Nuyens V, Reye F, Rousseau A, Raes M, Moguilevsky N, Vanhaeverbeek M, Ducobu J, Nève J, Robaye B, Vanhamme L, Reynolds WF, Obinger C, Van Antwerpen P. Myeloperoxidase-catalyzed oxidation of cyanide to cyanate: A potential carbamylation route involved in the formation of atherosclerotic plaques? J Biol Chem 2018; 293:6374-6386. [PMID: 29496995 DOI: 10.1074/jbc.m117.801076] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 02/20/2018] [Indexed: 01/03/2023] Open
Abstract
Protein carbamylation by cyanate is a post-translational modification associated with several (patho)physiological conditions, including cardiovascular disorders. However, the biochemical pathways leading to protein carbamylation are incompletely characterized. This work demonstrates that the heme protein myeloperoxidase (MPO), which is secreted at high concentrations at inflammatory sites from stimulated neutrophils and monocytes, is able to catalyze the two-electron oxidation of cyanide to cyanate and promote the carbamylation of taurine, lysine, and low-density lipoproteins. We probed the role of cyanide as both electron donor and low-spin ligand by pre-steady-state and steady-state kinetic analyses and analyzed reaction products by MS. Moreover, we present two further pathways of carbamylation that involve reaction products of MPO, namely oxidation of cyanide by hypochlorous acid and reaction of thiocyanate with chloramines. Finally, using an in vivo approach with mice on a high-fat diet and carrying the human MPO gene, we found that during chronic exposure to cyanide, mimicking exposure to pollution and smoking, MPO promotes protein-bound accumulation of carbamyllysine (homocitrulline) in atheroma plaque, demonstrating a link between cyanide exposure and atheroma. In summary, our findings indicate that cyanide is a substrate for MPO and suggest an additional pathway for in vivo cyanate formation and protein carbamylation that involves MPO either directly or via its reaction products hypochlorous acid or chloramines. They also suggest that chronic cyanide exposure could promote the accumulation of carbamylated proteins in atherosclerotic plaques.
Collapse
Affiliation(s)
- Cédric Delporte
- From the Laboratory of Pharmaceutical Chemistry and.,Analytical Platform, Faculty of Pharmacy, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Karim Zouaoui Boudjeltia
- the Laboratory of Experimental Medicine, CHU de Charleroi, A. Vésale Hospital, Université Libre de Bruxelles, 6110 Montigny-le-Tilleul, Belgium
| | - Paul G Furtmüller
- the Department of Chemistry, Division of Biochemistry, University of Natural Resources and Life Sciences (BOKU), 1180 Vienna, Austria
| | - Richard A Maki
- Torrey Pines Pharmaceuticals, Del Mar, California 92014.,the Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, California 92037
| | - Marc Dieu
- the Laboratory of Cellular Biology and
| | | | - Monika Soudi
- the Department of Chemistry, Division of Biochemistry, University of Natural Resources and Life Sciences (BOKU), 1180 Vienna, Austria
| | - Damien Dufour
- From the Laboratory of Pharmaceutical Chemistry and.,Analytical Platform, Faculty of Pharmacy, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Catherine Coremans
- From the Laboratory of Pharmaceutical Chemistry and.,Analytical Platform, Faculty of Pharmacy, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Vincent Nuyens
- the Laboratory of Experimental Medicine, CHU de Charleroi, A. Vésale Hospital, Université Libre de Bruxelles, 6110 Montigny-le-Tilleul, Belgium
| | | | - Alexandre Rousseau
- the Laboratory of Experimental Medicine, CHU de Charleroi, A. Vésale Hospital, Université Libre de Bruxelles, 6110 Montigny-le-Tilleul, Belgium
| | | | | | - Michel Vanhaeverbeek
- the Laboratory of Experimental Medicine, CHU de Charleroi, A. Vésale Hospital, Université Libre de Bruxelles, 6110 Montigny-le-Tilleul, Belgium
| | - Jean Ducobu
- the Laboratory of Experimental Medicine, CHU de Charleroi, A. Vésale Hospital, Université Libre de Bruxelles, 6110 Montigny-le-Tilleul, Belgium
| | - Jean Nève
- From the Laboratory of Pharmaceutical Chemistry and
| | - Bernard Robaye
- the Institute of Interdisciplinary Research, Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Sciences, Université Libre de Bruxelles, 6041 Gosselies, Belgium, and
| | - Luc Vanhamme
- the Laboratory of Molecular Parasitology, Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Sciences, Université Libre de Bruxelles, 6041 Gosselies, Belgium
| | - Wanda F Reynolds
- the Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, California 92037
| | - Christian Obinger
- the Department of Chemistry, Division of Biochemistry, University of Natural Resources and Life Sciences (BOKU), 1180 Vienna, Austria
| | - Pierre Van Antwerpen
- From the Laboratory of Pharmaceutical Chemistry and .,Analytical Platform, Faculty of Pharmacy, Université Libre de Bruxelles, 1050 Brussels, Belgium
| |
Collapse
|
7
|
Wu Z, Xu J, Liu Q, Dong X, Li D, Holzmann N, Frenking G, Trabelsi T, Francisco JS, Zeng X. The hypothiocyanite radical OSCN and its isomers. Phys Chem Chem Phys 2017. [PMID: 28621378 DOI: 10.1039/c7cp02774e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
An elusive biologically relevant hypothiocyanite radical (OSCN) has been generated in the gas phase, and its reversible photoisomerization with two novel isomers OSNC and SOCN has been observed in cryogenic Ar and N2 matrices at 2.8 K.
Collapse
Affiliation(s)
- Zhuang Wu
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- 215123 Suzhou
- P. R. China
| | - Jian Xu
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- 215123 Suzhou
- P. R. China
| | - Qifan Liu
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- 215123 Suzhou
- P. R. China
| | - Xuelin Dong
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- 215123 Suzhou
- P. R. China
| | - Dingqing Li
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- 215123 Suzhou
- P. R. China
| | - Nicole Holzmann
- STFC Rutherford Appleton Laboratory
- Harwell Oxford
- Didcot OX11 0QX
- UK
| | - Gernot Frenking
- Fachbereich Chemie
- Philipps-Universität Marburg
- Marburg D-35032
- Germany
- Donostia International Physics Center (DIPC)
| | - Tarek Trabelsi
- Department of Chemistry
- University of Nebraska – Lincoln
- Lincoln
- USA
| | | | - Xiaoqing Zeng
- College of Chemistry
- Chemical Engineering and Materials Science
- Soochow University
- 215123 Suzhou
- P. R. China
| |
Collapse
|
8
|
Ahmad S, Ahmad A, Hendry-Hofer TB, Loader JE, Claycomb WC, Mozziconacci O, Schöneich C, Reisdorph N, Powell RL, Chandler JD, Day BJ, Veress LA, White CW. Sarcoendoplasmic reticulum Ca(2+) ATPase. A critical target in chlorine inhalation-induced cardiotoxicity. Am J Respir Cell Mol Biol 2016; 52:492-502. [PMID: 25188881 DOI: 10.1165/rcmb.2014-0005oc] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Autopsy specimens from human victims or experimental animals that die due to acute chlorine gas exposure present features of cardiovascular pathology. We demonstrate acute chlorine inhalation-induced reduction in heart rate and oxygen saturation in rats. Chlorine inhalation elevated chlorine reactants, such as chlorotyrosine and chloramine, in blood plasma. Using heart tissue and primary cardiomyocytes, we demonstrated that acute high-concentration chlorine exposure in vivo (500 ppm for 30 min) caused decreased total ATP content and loss of sarcoendoplasmic reticulum calcium ATPase (SERCA) activity. Loss of SERCA activity was attributed to chlorination of tyrosine residues and oxidation of an important cysteine residue, cysteine-674, in SERCA, as demonstrated by immunoblots and mass spectrometry. Using cardiomyocytes, we found that chlorine-induced cell death and damage to SERCA could be decreased by thiocyanate, an important biological antioxidant, and by genetic SERCA2 overexpression. We also investigated a U.S. Food and Drug Administration-approved drug, ranolazine, used in treatment of cardiac diseases, and previously shown to stabilize SERCA in animal models of ischemia-reperfusion. Pretreatment with ranolazine or istaroxime, another SERCA activator, prevented chlorine-induced cardiomyocyte death. Further investigation of responsible mechanisms showed that ranolazine- and istaroxime-treated cells preserved mitochondrial membrane potential and ATP after chlorine exposure. Thus, these studies demonstrate a novel critical target for chlorine in the heart and identify potentially useful therapies to mitigate toxicity of acute chlorine exposure.
Collapse
Affiliation(s)
- Shama Ahmad
- 1 Pediatric Airway Research Center, Department of Pediatrics, University of Colorado, Denver, Aurora, Colorado
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Šakić D, Hanževački M, Smith DM, Vrček V. A computational study of the chlorination and hydroxylation of amines by hypochlorous acid. Org Biomol Chem 2015; 13:11740-52. [PMID: 26486691 DOI: 10.1039/c5ob01823d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The reactions of hypochlorous acid (HOCl) with ammonia, (di)methylamine, and heterocyclic amines have been studied computationally using double-hybrid DFT methods (B2PLYP-D and BK-PLYP) and a G3B3 composite scheme. In the gas phase the calculated energy barriers for N- and/or C-hydroxylation are ca. 100 kJ mol(-1) lower than the barrier for N-chlorination of amines. In the model solvent, however, the latter process becomes kinetically more favored. The explicit solvent effects are crucial for determination of the reaction mechanism. The N-chlorination is extremely susceptible to the presence of explicit water molecules, while no beneficial solvation effect has been found for the N- or C-hydroxylation of amines. The origin of the observed solvent effects arises from differential solvation of the respective transition states for chlorine- and oxygen-transfers, respectively. The nature of solvation of the transition state structures has been explored in more detail by classical molecular dynamics (MD) simulation. In agreement with the quantum mechanical approach, the most stable structural motif, which includes the amine, HOCl, and two reactive waters, has been identified during the MD simulation. The inclusion of 5 or 6 explicit water molecules is required to reproduce the experimental barriers for HOCl-induced formation of N-chloramines in an aqueous environment.
Collapse
Affiliation(s)
- Davor Šakić
- Faculty of Pharmacy and Biochemistry, University of Zagreb, A. Kovačića 1, 10000 Zagreb, Croatia.
| | | | | | | |
Collapse
|
10
|
Chandler JD, Min E, Huang J, McElroy CS, Dickerhof N, Mocatta T, Fletcher AA, Evans CM, Liang L, Patel M, Kettle AJ, Nichols DP, Day BJ. Antiinflammatory and Antimicrobial Effects of Thiocyanate in a Cystic Fibrosis Mouse Model. Am J Respir Cell Mol Biol 2015; 53:193-205. [PMID: 25490247 DOI: 10.1165/rcmb.2014-0208oc] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Thiocyanate (SCN) is used by the innate immune system, but less is known about its impact on inflammation and oxidative stress. Granulocytes oxidize SCN to evolve the bactericidal hypothiocyanous acid, which we previously demonstrated is metabolized by mammalian, but not bacterial, thioredoxin reductase (TrxR). There is also evidence that SCN is dysregulated in cystic fibrosis (CF), a disease marked by chronic infection and airway inflammation. To investigate antiinflammatory effects of SCN, we administered nebulized SCN or saline to β epithelial sodium channel (βENaC) mice, a phenotypic CF model. SCN significantly decreased airway neutrophil infiltrate and restored the redox ratio of glutathione in lung tissue and airway epithelial lining fluid to levels comparable to wild type. Furthermore, in Pseudomonas aeruginosa-infected βENaC and wild-type mice, SCN decreased inflammation, proinflammatory cytokines, and bacterial load. SCN also decreased airway neutrophil chemokine keratinocyte chemoattractant (also known as C-X-C motif chemokine ligand 1) and glutathione sulfonamide, a biomarker of granulocyte oxidative activity, in uninfected βENaC mice. Lung tissue TrxR activity and expression increased in inflamed lung tissue, providing in vivo evidence for the link between hypothiocyanous acid metabolism by TrxR and the promotion of selective biocide of pathogens. SCN treatment both suppressed inflammation and improved host defense, suggesting that nebulized SCN may have important therapeutic utility in diseases of both chronic airway inflammation and persistent bacterial infection, such as CF.
Collapse
Affiliation(s)
- Joshua D Chandler
- 1 Department of Pharmaceutical Sciences and.,Departments of 2 Medicine and
| | | | | | - Cameron S McElroy
- 1 Department of Pharmaceutical Sciences and.,Departments of 2 Medicine and
| | - Nina Dickerhof
- 3 Centre for Free Radical Research, Department of Pathology, University of Otago Christchurch, Christchurch, New Zealand
| | - Tessa Mocatta
- 3 Centre for Free Radical Research, Department of Pathology, University of Otago Christchurch, Christchurch, New Zealand
| | - Ashley A Fletcher
- 4 Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora, Colorado
| | - Christopher M Evans
- 4 Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Denver, Aurora, Colorado
| | | | | | - Anthony J Kettle
- 3 Centre for Free Radical Research, Department of Pathology, University of Otago Christchurch, Christchurch, New Zealand
| | - David P Nichols
- Departments of 2 Medicine and.,5 Pediatrics, National Jewish Health, Denver, Colorado; and
| | - Brian J Day
- 1 Department of Pharmaceutical Sciences and.,Departments of 2 Medicine and
| |
Collapse
|
11
|
Nedoboy PE, Morgan PE, Mocatta TJ, Richards AM, Winterbourn CC, Davies MJ. High plasma thiocyanate levels are associated with enhanced myeloperoxidase-induced thiol oxidation and long-term survival in subjects following a first myocardial infarction. Free Radic Res 2015; 48:1256-66. [PMID: 25050609 DOI: 10.3109/10715762.2014.947286] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Elevated levels of myeloperoxidase (MPO) are associated with poor cardiovascular outcomes. MPO uses H2O2 to generate oxidants including HOCl and HOSCN, from chloride and thiocyanate (SCN(-)) ions, respectively. SCN(-) is the preferred substrate. Elevation of this anion decreases HOCl generation and increases HOSCN formation, a thiol-specific oxidant. Such changes are of potential relevance to people with elevated SCN(-) levels, such as smokers. In this retrospective study, we examined whether elevated plasma MPO and SCN(-) levels increased thiol oxidation as a result of increased HOSCN formation, and impacted on long-term survival in 176 subjects (74 non-smokers, 46 smokers, and 56 previous smokers) hospitalized after a first myocardial infarction. Plasma thiols were not significantly altered in smokers compared to non-smokers or past smokers. However, significant positive correlations were detected between SCN(-) levels and MPO-induced thiol loss in the total population (r = 0.19, P = 0.020) and smokers alone (r = 0.58, P < 0.0001). Twelve-year all-cause mortality data indicate that above median MPO is significantly associated with higher mortality, but below-median MPO and above-median SCN(-) results in increased survival, compared to below-median SCN(-). Cox proportional hazard analysis showed a significant decrease in mortality for each 1 μM increase in SCN(-) (0.991; P = 0.040). Subject age was, as expected, a strong predictor of subject survival. Overall these data suggest that subjects with below-median MPO and above-median SCN(-) have better long-term survival, and that elevated plasma levels of SCN(-) might be protective in at least some populations.
Collapse
Affiliation(s)
- P E Nedoboy
- The Heart Research Institute , Newtown, Sydney , Australia
| | | | | | | | | | | |
Collapse
|
12
|
Chandler JD, Min E, Huang J, Nichols DP, Day BJ. Nebulized thiocyanate improves lung infection outcomes in mice. Br J Pharmacol 2015; 169:1166-77. [PMID: 23586967 DOI: 10.1111/bph.12206] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 03/14/2013] [Accepted: 03/28/2013] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND AND PURPOSE Nebulized saline solutions are used in the treatment of multiple pulmonary diseases including cystic fibrosis (CF), asthma and chronic obstructive pulmonary disease (COPD). The benefits of these therapies include improved lung function, phlegm clearance and fewer lung infections. The thiocyanate anion (SCN) is a normal component of the airway epithelial lining fluid (ELF) secreted by pulmonary epithelia with antioxidant and host defence functions. We sought to test if SCN could be nebulized to combat lung infection by bolstering innate immune defence and antioxidant capacity. EXPERIMENTAL APPROACH We established an effective antioxidant concentration of SCN in vitro using a bronchiolar epithelial cell line. We then developed a nebulization method of SCN in mice that increased ELF SCN above this concentration up to 12 h and used this method in a prolonged Pseudomonas aeruginosa infection model to test if increasing SCN improved host defence and infection outcomes. KEY RESULTS SCN protected against cytotoxicity in vitro from acute and sustained exposure to inflammation-associated oxidative stress. Nebulized SCN effectively reduced bacterial load, infection-mediated morbidity and airway inflammation in mice infected with P. aeruginosa. SCN also sustained adaptive increases in reduced GSH in infected mice. CONCLUSIONS AND IMPLICATIONS SCN is a dually protective molecule able to both enhance host defence and decrease tissue injury and inflammation as an antioxidant. Nebulized SCN could be developed to combat lung infections and inflammatory lung disease.
Collapse
Affiliation(s)
- J D Chandler
- Department of Medicine, National Jewish Health, Denver, CO 80206, USA
| | | | | | | | | |
Collapse
|
13
|
Chandler JD, Day BJ. Biochemical mechanisms and therapeutic potential of pseudohalide thiocyanate in human health. Free Radic Res 2015; 49:695-710. [PMID: 25564094 DOI: 10.3109/10715762.2014.1003372] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Thiocyanate (SCN(-)) is a ubiquitous molecule in mammalian biology, reaching up to mM concentrations in extracellular fluids. Two- electron oxidation of SCN(-) by H2O2 produces hypothiocyanous acid (HOSCN), a potent anti-microbial species. This reaction is catalyzed by chordate peroxidases (e.g., myeloperoxidase and lactoperoxidase), occurring in human secretory mucosa, including the oral cavity, airway, and alimentary tract, and regulates resident and transient flora as part of innate immunity. Increasing SCN(-) levels limits the concentrations of a family of 2-electron oxidants (H2O2, hypohalous acids, and haloamines) in favor of HOSCN formation, altering the oxidative impact on host tissue by substitution of repairable thiol and selenol oxidations instead of biomolecule degradation. This fine-tuning of inflammatory oxidation paradoxically associates with maintained host defense and decreased host injury during infections, due in part to phylogenetic differences in the thioredoxin reductase system between mammals and their pathogens. These differences could be exploited by pharmacologic use of SCN(-). Recent preclinical studies have identified anti-microbial and anti-inflammatory effects of SCN(-) in pulmonary and cardiovascular animal models, with implications for treatment of infectious lung disease and atherogenesis. Further research is merited to expand on these findings and identify other diseases where SCN(-) may be of use. High oral bioavailability and an increased knowledge of the biochemical effects of SCN(-) on a subset of pro-inflammatory reactions suggest clinical utility.
Collapse
|
14
|
Galajda M, Fodor T, Purgel M, Fábián I. The kinetics and mechanism of the oxidation of pyruvate ion by hypochlorous acid. RSC Adv 2015. [DOI: 10.1039/c4ra12789g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Kinetic experiments and DFT calculations confirm a concerted oxygen atom transfer mechanism for the oxidation of pyruvic acid by HOCl.
Collapse
Affiliation(s)
- Mónika Galajda
- MTA-DE Homogeneous Catalysis and Reaction Mechanisms Research Group
- Debrecen
- Hungary
| | - Tímea Fodor
- Department of Inorganic and Analytical Chemistry
- University of Debrecen
- Debrecen
- Hungary
| | - Mihály Purgel
- MTA-DE Homogeneous Catalysis and Reaction Mechanisms Research Group
- Debrecen
- Hungary
| | - István Fábián
- Department of Inorganic and Analytical Chemistry
- University of Debrecen
- Debrecen
- Hungary
| |
Collapse
|
15
|
Chandler JD, Nichols DP, Nick JA, Hondal RJ, Day BJ. Selective metabolism of hypothiocyanous acid by mammalian thioredoxin reductase promotes lung innate immunity and antioxidant defense. J Biol Chem 2013; 288:18421-8. [PMID: 23629660 DOI: 10.1074/jbc.m113.468090] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The endogenously produced oxidant hypothiocyanous acid (HOSCN) inhibits and kills pathogens but paradoxically is well tolerated by mammalian host tissue. Mammalian high molecular weight thioredoxin reductase (H-TrxR) is evolutionarily divergent from bacterial low molecular weight thioredoxin reductase (L-TrxR). Notably, mammalian H-TrxR contains a selenocysteine (Sec) and has wider substrate reactivity than L-TrxR. Recombinant rat cytosolic H-TrxR1, mouse mitochondrial H-TrxR2, and a purified mixture of both from rat selectively turned over HOSCN (kcat = 357 ± 16 min(-1); Km = 31.9 ± 10.3 μM) but were inactive against the related oxidant hypochlorous acid. Replacing Sec with Cys or deleting the final eight C-terminal peptides decreased affinity and turnover of HOSCN by H-TrxR. Similarly, glutathione reductase (an H-TrxR homologue lacking Sec) was less effective at HOSCN turnover. In contrast to H-TrxR and glutathione reductase, recombinant Escherichia coli L-TrxR was potently inhibited by HOSCN (IC50 = 2.75 μM). Similarly, human bronchial epithelial cell (16HBE) lysates metabolized HOSCN, but E. coli and Pseudomonas aeruginosa lysates had little or no activity. HOSCN selectively produced toxicity in bacteria, whereas hypochlorous acid was nonselectively toxic to both bacteria and 16HBE. Treatment with the H-TrxR inhibitor auranofin inhibited HOSCN metabolism in 16HBE lysates and significantly increased HOSCN-mediated cytotoxicity. These findings demonstrate both the metabolism of HOSCN by mammalian H-TrxR resulting in resistance to HOSCN in mammalian cells and the potent inhibition of bacterial L-TrxR resulting in cytotoxicity in bacteria. These data support a novel selective mechanism of host defense in mammals wherein HOSCN formation simultaneously inhibits pathogens while sparing host tissue.
Collapse
Affiliation(s)
- Joshua D Chandler
- Department of Pharmaceutical Sciences, University of Colorado Denver, Aurora, Colorado 80045, USA
| | | | | | | | | |
Collapse
|
16
|
Sandvik EL, McLeod BR, Parker AE, Stewart PS. Direct electric current treatment under physiologic saline conditions kills Staphylococcus epidermidis biofilms via electrolytic generation of hypochlorous acid. PLoS One 2013; 8:e55118. [PMID: 23390518 PMCID: PMC3563656 DOI: 10.1371/journal.pone.0055118] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 12/19/2012] [Indexed: 01/25/2023] Open
Abstract
The purpose of this study was to investigate the mechanism by which a direct electrical current reduced the viability of Staphylococcus epidermidis biofilms in conjunction with ciprofloxacin at physiologic saline conditions meant to approximate those in an infected artificial joint. Biofilms grown in CDC biofilm reactors were exposed to current for 24 hours in 1/10th strength tryptic soy broth containing 9 g/L total NaCl. Dose-dependent log reductions up to 6.7 log10 CFU/cm2 were observed with the application of direct current at all four levels (0.7 to 1.8 mA/cm2) both in the presence and absence of ciprofloxacin. There were no significant differences in log reductions for wells with ciprofloxacin compared to those without at the same current levels. When current exposures were repeated without biofilm or organics in the medium, significant generation of free chlorine was measured. Free chlorine doses equivalent to the 24 hour endpoint concentration for each current level were shown to mimic killing achieved by current application. Current exposure (1.8 mA/cm2) in medium lacking chloride and amended with sulfate, nitrate, or phosphate as alternative electrolytes produced diminished kills of 3, 2, and 0 log reduction, respectively. Direct current also killed Pseudomonas aeruginosa biofilms when NaCl was present. Together these results indicate that electrolysis reactions generating hypochlorous acid from chloride are likely a main contributor to the efficacy of direct current application. A physiologically relevant NaCl concentration is thus a critical parameter in experimental design if direct current is to be investigated for in vivo medical applications.
Collapse
Affiliation(s)
- Elizabeth L. Sandvik
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, United States of America
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, Montana, United States of America
| | - Bruce R. McLeod
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, United States of America
- Department of Electrical and Computer Engineering, Montana State University, Bozeman, Montana, United States of America
| | - Albert E. Parker
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, United States of America
- Department of Mathematical Sciences, Montana State University, Bozeman, Montana, United States of America
| | - Philip S. Stewart
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, United States of America
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, Montana, United States of America
- * E-mail:
| |
Collapse
|
17
|
Takahama U, Ansai T, Hirota S. Nitrogen Oxides Toxicology of the Aerodigestive Tract. ADVANCES IN MOLECULAR TOXICOLOGY 2013. [DOI: 10.1016/b978-0-444-62645-5.00004-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
18
|
Holzer M, Zangger K, El-Gamal D, Binder V, Curcic S, Konya V, Schuligoi R, Heinemann A, Marsche G. Myeloperoxidase-derived chlorinating species induce protein carbamylation through decomposition of thiocyanate and urea: novel pathways generating dysfunctional high-density lipoprotein. Antioxid Redox Signal 2012; 17:1043-52. [PMID: 22462773 PMCID: PMC3810648 DOI: 10.1089/ars.2011.4403] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
AIMS Protein carbamylation through cyanate is considered as playing a causal role in promoting cardiovascular disease. We recently observed that the phagocyte protein myeloperoxidase (MPO) specifically induces high-density lipoprotein (HDL) carbamylation, rather than chlorination, in human atherosclerotic lesions, raising the possibility that MPO-derived chlorinating species are involved in cyanate formation. RESULTS Here, we show that MPO-derived chlorinating species rapidly decompose the plasma components thiocyanate (SCN) and urea, thereby promoting (lipo)protein carbamylation. Strikingly, the presence of physiologic concentrations of SCN completely prevented MPO-induced 3-chlorotyrosine formation in HDL. SCN scavenged a 2.5-fold molar excess of hypochlorous acid, promoting HDL carbamylation, but not chlorination. Cyanate significantly impaired (i) HDL's ability to activate lecithin-cholesterol acyltransferase; (ii) the activity of paraoxonase, a major HDL-associated anti-inflammatory enzyme; and (iii) the antioxidative activity of HDL. INNOVATION Here, we report that MPO-derived chlorinating species preferentially induce protein carbamylation-rather than chlorination-in the presence of physiologically relevant SCN concentrations. The carbamylation of HDL results in the loss of its anti-inflammatory and antioxidative activities. CONCLUSION MPO-mediated decomposition of SCN and/or urea might be a relevant mechanism for generating dysfunctional HDL in human disease.
Collapse
Affiliation(s)
- Michael Holzer
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| | - Klaus Zangger
- Institute of Chemistry/Organic and Bioorganic Chemistry, University of Graz, Austria
| | - Dalia El-Gamal
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| | - Veronika Binder
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| | - Sanja Curcic
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| | - Viktoria Konya
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| | - Rufina Schuligoi
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| | - Akos Heinemann
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| | - Gunther Marsche
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| |
Collapse
|
19
|
Chandler JD, Day BJ. Thiocyanate: a potentially useful therapeutic agent with host defense and antioxidant properties. Biochem Pharmacol 2012; 84:1381-7. [PMID: 22968041 DOI: 10.1016/j.bcp.2012.07.029] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 07/26/2012] [Accepted: 07/26/2012] [Indexed: 12/15/2022]
Abstract
Thiocyanate (SCN) functions in host defense as part of the secreted lactoperoxidase (LPO) microbicidal pathway. SCN is the preferred substrate for LPO-driven catalytic reduction of hydrogen peroxide (H(2)O(2)) forming hypothiocyanous acid (HOSCN). HOSCN is selectively generated by many peroxidase enzymes that can utilize SCN including: eosinophil peroxidase (EPO), gastric peroxidase (GPO), myeloperoxidase (MPO), salivary peroxidase (SPO), and thyroid peroxidase (TPO). These enzymes generate HOSCN through a two-electron halogenation reaction. HOSCN is a potent microbicidal agent that kills or nullifies invading pathogens but is better tolerated by host tissue. Some controversy exists as to whether physiologic levels of HOSCN are non-toxic to host tissue, but the disagreement appears to be based on results of enzymatic generation (yielding moderate steady-state exposure) versus direct high level acute exposure in mammalian cell lines. This apparent duality is also true of other endogenous oxidants such as hydrogen peroxide and relates to the difference between physiologically relevant oxidant production versus supra-physiologic bolus dosing approaches. SCN has antioxidant properties that include the ability to protect cells against oxidizing agents such as hypochlorous acid (HOCl) and repair protein chloramines. SCN is an important endogenous molecule that has the potential to interact in complex and elegant ways with its host environment and foreign organisms. SCN's diverse properties as both host defense and antioxidant agent make it a potentially useful therapeutic.
Collapse
Affiliation(s)
- Joshua D Chandler
- Department of Medicine, National Jewish Health, Denver, CO 80206, United States
| | | |
Collapse
|
20
|
Pattison DI, Davies MJ, Hawkins CL. Reactions and reactivity of myeloperoxidase-derived oxidants: Differential biological effects of hypochlorous and hypothiocyanous acids. Free Radic Res 2012; 46:975-95. [DOI: 10.3109/10715762.2012.667566] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
21
|
|
22
|
Abstract
Hypothiocyanous acid (HOSCN) is produced in biological systems by the peroxidase-catalyzed reaction of thiocyanate (SCN(-)) with H(2)O(2). This oxidant plays an important role in the human immune system, owing to its potent bacteriostatic properties. Significant amounts of HOSCN are also formed by immune cells under inflammatory conditions, yet the reactivity of this oxidant with host tissue is poorly characterized. Traditionally, HOSCN has been viewed as a mild oxidant, which is innocuous to mammalian cells. Indeed, recent studies show that the presence of SCN(-) in airways has a protective function, by preventing the formation of other, more damaging, inflammatory oxidants. However, there is an increasing body of evidence that challenges this dogma, showing that the selectivity of HOSCN for specific thiol-containing cellular targets results in the initiation of significant cellular damage. This propensity to induce cellular dysfunction is gaining considerable interest, particularly in the cardiovascular field, as smokers have elevated plasma SCN(-), the precursor for HOSCN. This review will outline the beneficial and detrimental aspects of HOSCN formation in biological systems.
Collapse
Affiliation(s)
- Tessa J Barrett
- Inflammation Group, The Heart Research Institute , 7 Eliza Street, Newtown, Sydney, NSW 2042, Australia
| | | |
Collapse
|