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Jokumsen KV, Huhle VH, Hägglund PM, Davies MJ, Gamon LF. Elevated levels of iodide promote peroxidase-mediated protein iodination and inhibit protein chlorination. Free Radic Biol Med 2024; 220:207-221. [PMID: 38663830 DOI: 10.1016/j.freeradbiomed.2024.04.230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 04/18/2024] [Indexed: 05/15/2024]
Abstract
At inflammatory sites, immune cells generate oxidants including H₂O₂. Myeloperoxidase (MPO), released by activated leukocytes employs H₂O₂ and halide/pseudohalides to form hypohalous acids that mediate pathogen killing. Hypochlorous acid (HOCl) is a major species formed. Excessive or misplaced HOCl formation damages host tissues with this linked to multiple inflammatory diseases. Previously (Redox Biology, 2020, 28, 101331) we reported that iodide (I⁻) modulates MPO-mediated protein damage by decreasing HOCl generation with concomitant hypoiodous acid (HOI) formation. HOI may however impact on protein structure, so in this study we examined whether and how HOI, from peroxidase/H₂O₂/I⁻ systems ± Cl⁻, modifies proteins. Experiments employed MPO and lactoperoxidase (LPO) and multiple proteins (serum albumins, anastellin), with both chemical (intact protein and peptide mass mapping, LC-MS) and structural (SDS-PAGE) changes assessed. LC-MS analyses revealed dose-dependent iodination of anastellin and albumins by LPO/H2O2 with increasing I⁻. Incubation of BSA with MPO/H2O2/Cl⁻ revealed modest chlorination (Tyr286, Tyr475, ∼4 %) and Met modification. Lower levels of these species, and extensive iodination at specific Tyr and His residues (>20 % modification with ≥10 μM I⁻) were detected with increasing I⁻. Anastellin dimerization was inhibited by increasing I⁻, but less marked changes were observed with albumins. These data confirm that I⁻ competes with Cl⁻ for MPO and is an efficient HOCl scavenger. These processes decrease protein chlorination and oxidation, but result in extensive iodination. This is consistent with published data on the presence of iodinated Tyr on neutrophil proteins. The biological implications of protein iodination relative to chlorination require further clarification.
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Affiliation(s)
| | - Valerie H Huhle
- Dept. of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin, Berlin, Germany
| | - Per M Hägglund
- Dept. of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael J Davies
- Dept. of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Luke F Gamon
- Dept. of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
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2
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Reynolds WF, Malle E, Maki RA. Thiocyanate Reduces Motor Impairment in the hMPO-A53T PD Mouse Model While Reducing MPO-Oxidation of Alpha Synuclein in Enlarged LYVE1/AQP4 Positive Periventricular Glymphatic Vessels. Antioxidants (Basel) 2022; 11:antiox11122342. [PMID: 36552550 PMCID: PMC9774557 DOI: 10.3390/antiox11122342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 11/23/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Parkinson's disease (PD) is due to the oxidation of alpha synuclein (αSyn) contributing to motor impairment. We developed a transgenic mouse model of PD that overexpresses the mutated human αSyn gene (A53T) crossed to a mouse expressing the human MPO gene. This model exhibits increased oxidation and chlorination of αSyn leading to greater motor impairment. In the current study, the hMPO-A53T mice were treated with thiocyanate (SCN-) which is a favored substrate of MPO as compared to chlorine. We show that hMPO-A53T mice treated with SCN- have less chlorination in the brain and show an improvement in motor skills compared to the nontreated hMPO-A53T mice. Interestingly, in the hMPO-A53T mice we found a possible link between MPO-related disease and the glymphatic system which clears waste including αSyn from the brain. The untreated hMPO-A53T mice exhibited an increase in the size of periventricular glymphatic vessels expressing the glymphatic marker LYVE1 and aquaporin 4 (AQP4). These vessels also exhibited an increase in MPO and HOCl-modified epitopes in the glymphatic vessels correlating with loss of ependymal cells lining the ventricles. These findings suggest that MPO may significantly promote the impairment of the glymphatic waste removal system thus contributing to neurodegeneration in PD. Moreover, the inhibition of MPO chlorination/oxidation by SCN- may provide a potential therapeutic approach to this disease.
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Affiliation(s)
- Wanda F. Reynolds
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
- Correspondence:
| | - Ernst Malle
- Gottfried Schatz Research Center, Division of Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Richard A. Maki
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
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Xu S, Chuang CY, Malle E, Gamon LF, Hawkins CL, Davies MJ. Influence of plasma halide, pseudohalide and nitrite ions on myeloperoxidase-mediated protein and extracellular matrix damage. Free Radic Biol Med 2022; 188:162-174. [PMID: 35718304 DOI: 10.1016/j.freeradbiomed.2022.06.222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 06/11/2022] [Indexed: 01/15/2023]
Abstract
Myeloperoxidase (MPO) mediates pathogen destruction by generating the bactericidal oxidant hypochlorous acid (HOCl). Formation of this oxidant is however associated with host tissue damage and disease. MPO also utilizes H2O2 to oxidize other substrates, and we hypothesized that mixtures of other plasma anions, including bromide (Br-), iodide (I-), thiocyanate (SCN-) and nitrite (NO2-), at normal or supplemented concentrations, might modulate MPO-mediated HOCl damage. For the (pseudo)halide anions, only SCN- significantly modulated HOCl formation (IC50 ∼33 μM), which is within the normal physiological range, as judged by damage to human plasma fibronectin or extracellular matrix preparations detected by ELISA and LC-MS. NO2- modulated HOCl-mediated damage, in a dose-dependent manner, at physiologically-attainable anion concentrations. However, this was accompanied by increased tyrosine and tryptophan nitration (detected by ELISA and LC-MS), and the overall extent of damage remained approximately constant. Increasing NO2- concentrations (0.5-20 μM) diminished HOCl-mediated modification of tyrosine and methionine, whereas tryptophan loss was enhanced. At higher NO2- concentrations, enhanced tyrosine and methionine loss was detected. These analytical data were confirmed in studies of cell adhesion and metabolic activity. Together, these data indicate that endogenous plasma levels of SCN- (but not Br- or I-) can modulate protein modification induced by MPO, including the extent of chlorination. In contrast, NO2- alters the type of modification, but does not markedly decrease its extent, with chlorination replaced by nitration. These data also indicate that MPO could be a major source of nitration in vivo, and particularly at inflammatory sites where NO2- levels are often elevated.
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Affiliation(s)
- Shuqi Xu
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Christine Y Chuang
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Ernst Malle
- Division of Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Luke F Gamon
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Clare L Hawkins
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Michael J Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark.
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4
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Khilazheva ED, Lychkovskaya EV, Kutyakov VA, Morgun AV, Salmin VV. In vitro Effects of Plasma Acid on Proliferation of Rat Brain Endothelial Cells. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022040196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Arnhold J, Malle E. Halogenation Activity of Mammalian Heme Peroxidases. Antioxidants (Basel) 2022; 11:antiox11050890. [PMID: 35624754 PMCID: PMC9138014 DOI: 10.3390/antiox11050890] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 12/10/2022] Open
Abstract
Mammalian heme peroxidases are fascinating due to their unique peculiarity of oxidizing (pseudo)halides under physiologically relevant conditions. These proteins are able either to incorporate oxidized halides into substrates adjacent to the active site or to generate different oxidized (pseudo)halogenated species, which can take part in multiple (pseudo)halogenation and oxidation reactions with cell and tissue constituents. The present article reviews basic biochemical and redox mechanisms of (pseudo)halogenation activity as well as the physiological role of heme peroxidases. Thyroid peroxidase and peroxidasin are key enzymes for thyroid hormone synthesis and the formation of functional cross-links in collagen IV during basement membrane formation. Special attention is directed to the properties, enzymatic mechanisms, and resulting (pseudo)halogenated products of the immunologically relevant proteins such as myeloperoxidase, eosinophil peroxidase, and lactoperoxidase. The potential role of the (pseudo)halogenated products (hypochlorous acid, hypobromous acid, hypothiocyanite, and cyanate) of these three heme peroxidases is further discussed.
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Affiliation(s)
- Jürgen Arnhold
- Medical Faculty, Institute of Medical Physics and Biophysics, Leipzig University, 04107 Leipzig, Germany
- Correspondence: (J.A.); or (E.M.)
| | - Ernst Malle
- Gottfried Schatz Research Center, Division of Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
- Correspondence: (J.A.); or (E.M.)
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Oral pre-treatment with thiocyanate (SCN -) protects against myocardial ischaemia-reperfusion injury in rats. Sci Rep 2021; 11:12712. [PMID: 34135432 PMCID: PMC8209016 DOI: 10.1038/s41598-021-92142-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/07/2021] [Indexed: 01/15/2023] Open
Abstract
Despite improvements in revascularization after a myocardial infarction, coronary disease remains a major contributor to global mortality. Neutrophil infiltration and activation contributes to tissue damage, via the release of myeloperoxidase (MPO) and formation of the damaging oxidant hypochlorous acid. We hypothesized that elevation of thiocyanate ions (SCN−), a competitive MPO substrate, would modulate tissue damage. Oral dosing of rats with SCN−, before acute ischemia–reperfusion injury (30 min occlusion, 24 h or 4 week recovery), significantly reduced the infarct size as a percentage of the total reperfused area (54% versus 74%), and increased the salvageable area (46% versus 26%) as determined by MRI imaging. No difference was observed in fractional shortening, but supplementation resulted in both left-ventricle end diastolic and left-ventricle end systolic areas returning to control levels, as determined by echocardiography. Supplementation also decreased antibody recognition of HOCl-damaged myocardial proteins. SCN− supplementation did not modulate serum markers of damage/inflammation (ANP, BNP, galectin-3, CRP), but returned metabolomic abnormalities (reductions in histidine, creatine and leucine by 0.83-, 0.84- and 0.89-fold, respectively), determined by NMR, to control levels. These data indicate that elevated levels of the MPO substrate SCN−, which can be readily modulated by dietary means, can protect against acute ischemia–reperfusion injury.
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Flouda K, Mercer J, Davies MJ, Hawkins CL. Role of myeloperoxidase-derived oxidants in the induction of vascular smooth muscle cell damage. Free Radic Biol Med 2021; 166:165-177. [PMID: 33631301 DOI: 10.1016/j.freeradbiomed.2021.02.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/14/2021] [Indexed: 01/12/2023]
Abstract
Myeloperoxidase (MPO) is released by activated immune cells and forms the oxidants hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN) from the competing substrates chloride and thiocyanate. MPO and the overproduction of HOCl are strongly linked with vascular cell dysfunction and inflammation in atherosclerosis. HOCl is highly reactive and causes marked cell dysfunction and death, whereas data with HOSCN are conflicting, and highly dependent on the nature of the cell type. In this study we have examined the reactivity of HOCl and HOSCN with human coronary artery smooth muscle cells (HCASMC), given the key role of this cell type in maintaining vascular function. HOCl reacts rapidly with the cells, resulting in extensive cell death by both necrosis and apoptosis, and increased levels of intracellular calcium. In contrast, HOSCN reacts more slowly, with cell death occurring only after prolonged incubation, and in the absence of the accumulation of intracellular calcium. Exposure of HCASMC to HOCl also influences mitochondrial respiration, decreases glycolysis, lactate release, the production of ATP, cellular thiols and glutathione levels. These changes occurred to varying extents on exposure of the cells to HOSCN, where evidence was also obtained for the reversible modification of cellular thiols. HOCl also induced alterations in the mRNA expression of multiple inflammatory and phenotypic genes. Interestingly, the extent and nature of these changes was highly dependent on the specific cell donor used, with more marked effects observed in cells isolated from diseased compared to healthy vessels. Overall, these data provide new insight into pathways promoting vascular dysfunction during chronic inflammation, support the use of thiocyanate as a means to modulate MPO-induced cellular damage in atherosclerosis.
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Affiliation(s)
- Konstantina Flouda
- Department of Biomedical Sciences, University of Copenhagen, Panum, Blegdamsvej 3B, Copenhagen N, DK-2200, Denmark
| | - John Mercer
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, 126 University Place, Glasgow, G12 8TA, United Kingdom
| | - Michael J Davies
- Department of Biomedical Sciences, University of Copenhagen, Panum, Blegdamsvej 3B, Copenhagen N, DK-2200, Denmark
| | - Clare L Hawkins
- Department of Biomedical Sciences, University of Copenhagen, Panum, Blegdamsvej 3B, Copenhagen N, DK-2200, Denmark.
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8
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Homme RP, Sandhu HS, George AK, Tyagi SC, Singh M. Sustained Inhibition of NF-κB Activity Mitigates Retinal Vasculopathy in Diabetes. THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:947-964. [PMID: 33640319 DOI: 10.1016/j.ajpath.2021.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 01/13/2021] [Accepted: 01/20/2021] [Indexed: 12/12/2022]
Abstract
This study investigated the effects of long-term NF-κB inhibition in mitigating retinal vasculopathy in a type 1 diabetic mouse model (Akita, Ins2Akita). Akita and wild-type (C57BL/6J) male mice, 24 to 26 weeks old, were treated with or without a selective inhibitor of NF-κB, 4-methyl-N1-(3-phenyl-propyl) benzene-1,2-diamine (JSH-23), for 4 weeks. Treatment was given when the mice were at least 24 weeks old. Metabolic parameters, key inflammatory mediators, blood-retinal barrier junction molecules, retinal structure, and function were measured. JSH-23 significantly lowered basal glucose levels and intraocular pressure in Akita. It also mitigated vascular remodeling and microaneurysms significantly. Optical coherence tomography of untreated Akita showed thinning of retinal layers; however, treatment with JSH-23 could prevent it. Electroretinogram demonstrated that A- and B-waves in Akita were significantly smaller than in wild type mice, indicating that JSH-23 intervention prevented loss of retinal function. Protein levels and gene expression of key inflammatory mediators, such as NOD-like receptor family pyrin domain-containing 3, intercellular adhesion molecule-1, inducible nitric oxide synthase, and cyclooxygenase-2, were decreased after JSH-23 treatment. At the same time, connexin-43 and occludin were maintained. Vision-guided behavior also improved significantly. The results show that reducing inflammation could protect the diabetic retina and its vasculature. Findings appear to have broader implications in treating not only ocular conditions but also other vasculopathies.
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Affiliation(s)
- Rubens P Homme
- Eye and Vision Science Laboratory, University of Louisville School of Medicine, Louisville, Kentucky; Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky
| | - Harpal S Sandhu
- Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, Louisville, Kentucky; Kentucky Lions Eye Center, University of Louisville School of Medicine, Louisville, Kentucky
| | - Akash K George
- Eye and Vision Science Laboratory, University of Louisville School of Medicine, Louisville, Kentucky; Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky
| | - Suresh C Tyagi
- Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky
| | - Mahavir Singh
- Eye and Vision Science Laboratory, University of Louisville School of Medicine, Louisville, Kentucky; Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky.
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Vasilyev V, Sokolov A, Kostevich V, Elizarova A, Gorbunov N, Panasenko O. Binding of lactoferrin to the surface of low-density lipoproteins modified by myeloperoxidase prevents intracellular cholesterol accumulation by human blood monocytes. Biochem Cell Biol 2021; 99:109-116. [DOI: 10.1139/bcb-2020-0141] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Myeloperoxidase (MPO) is a unique heme-containing peroxidase that can catalyze the formation of hypochlorous acid (HOCl). The strong interaction of MPO with low-density lipoproteins (LDL) promotes proatherogenic modification of LDL by HOCl. The MPO-modified LDL (Mox-LDL) accumulate in macrophages, resulting in the formation of foam cells, which is the pathognomonic symptom of atherosclerosis. A promising approach to prophylaxis and atherosclerosis therapy is searching for remedies that prevent the modification or accumulation of LDL in macrophages. Lactoferrin (LF) has several application points in obesity pathogenesis. We aimed to study LF binding to Mox-LDL and their accumulation in monocytes transformed into macrophages. Using surface plasmon resonance and ELISA techniques, we observed no LF interaction with intact LDL, whereas Mox-LDL strongly interacted with LF. The affinity of Mox-LDL to LF increased with the degree of oxidative modification of LDL. Moreover, an excess of MPO did not prevent interaction of Mox-LDL with LF. LF inhibits accumulation of cholesterol in macrophages exposed to Mox-LDL. The results obtained reinforce the notion of LF potency as a remedy against atherosclerosis.
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Affiliation(s)
- V.B. Vasilyev
- FSBSI (Institute of Experimental Medicine), Saint Petersburg 197376, Russia
- Saint Petersburg State University, Saint Petersburg 199034, Russia
| | - A.V. Sokolov
- FSBSI (Institute of Experimental Medicine), Saint Petersburg 197376, Russia
- Saint Petersburg State University, Saint Petersburg 199034, Russia
- Federal Research and Clinical Center of Physical–Chemical Medicine of Federal Medical Biological Agency, Moscow 119435, Russia
| | - V.A. Kostevich
- FSBSI (Institute of Experimental Medicine), Saint Petersburg 197376, Russia
- Federal Research and Clinical Center of Physical–Chemical Medicine of Federal Medical Biological Agency, Moscow 119435, Russia
| | - A.Yu. Elizarova
- FSBSI (Institute of Experimental Medicine), Saint Petersburg 197376, Russia
| | - N.P. Gorbunov
- FSBSI (Institute of Experimental Medicine), Saint Petersburg 197376, Russia
- Federal Research and Clinical Center of Physical–Chemical Medicine of Federal Medical Biological Agency, Moscow 119435, Russia
| | - O.M. Panasenko
- Federal Research and Clinical Center of Physical–Chemical Medicine of Federal Medical Biological Agency, Moscow 119435, Russia
- Pirogov Russian National Research Medical University, Moscow 117997, Russia
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10
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Myeloperoxidase: Mechanisms, reactions and inhibition as a therapeutic strategy in inflammatory diseases. Pharmacol Ther 2021; 218:107685. [DOI: 10.1016/j.pharmthera.2020.107685] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/09/2020] [Indexed: 12/17/2022]
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11
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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−.
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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.
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Myeloperoxidase Modulates Hydrogen Peroxide Mediated Cellular Damage in Murine Macrophages. Antioxidants (Basel) 2020; 9:antiox9121255. [PMID: 33321763 PMCID: PMC7764223 DOI: 10.3390/antiox9121255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/02/2020] [Accepted: 12/07/2020] [Indexed: 11/17/2022] Open
Abstract
Myeloperoxidase (MPO) is involved in the development of many chronic inflammatory diseases, in addition to its key role in innate immune defenses. This is attributed to the excessive production of hypochlorous acid (HOCl) by MPO at inflammatory sites, which causes tissue damage. This has sparked wide interest in the development of therapeutic approaches to prevent HOCl-induced cellular damage including supplementation with thiocyanate (SCN-) as an alternative substrate for MPO. In this study, we used an enzymatic system composed of glucose oxidase (GO), glucose, and MPO in the absence and presence of SCN-, to investigate the effects of generating a continuous flux of oxidants on macrophage cell function. Our studies show the generation of hydrogen peroxide (H2O2) by glucose and GO results in a dose- and time-dependent decrease in metabolic activity and cell viability, and the activation of stress-related signaling pathways. Interestingly, these damaging effects were attenuated by the addition of MPO to form HOCl. Supplementation with SCN-, which favors the formation of hypothiocyanous acid, could reverse this effect. Addition of MPO also resulted in upregulation of the antioxidant gene, NAD(P)H:quinone acceptor oxidoreductase 1. This study provides new insights into the role of MPO in the modulation of macrophage function, which may be relevant to inflammatory pathologies.
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Myeloperoxidase: A versatile mediator of endothelial dysfunction and therapeutic target during cardiovascular disease. Pharmacol Ther 2020; 221:107711. [PMID: 33137376 DOI: 10.1016/j.pharmthera.2020.107711] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 10/01/2020] [Indexed: 02/06/2023]
Abstract
Myeloperoxidase (MPO) is a prominent mammalian heme peroxidase and a fundamental component of the innate immune response against microbial pathogens. In recent times, MPO has received considerable attention as a key oxidative enzyme capable of impairing the bioactivity of nitric oxide (NO) and promoting endothelial dysfunction; a clinically relevant event that manifests throughout the development of inflammatory cardiovascular disease. Increasing evidence indicates that during cardiovascular disease, MPO is released intravascularly by activated leukocytes resulting in its transport and sequestration within the vascular endothelium. At this site, MPO catalyzes various oxidative reactions that are capable of promoting vascular inflammation and impairing NO bioactivity and endothelial function. In particular, MPO catalyzes the production of the potent oxidant hypochlorous acid (HOCl) and the catalytic consumption of NO via the enzyme's NO oxidase activity. An emerging paradigm is the ability of MPO to also influence endothelial function via non-catalytic, cytokine-like activities. In this review article we discuss the implications of our increasing knowledge of the versatility of MPO's actions as a mediator of cardiovascular disease and endothelial dysfunction for the development of new pharmacological agents capable of effectively combating MPO's pathogenic activities. More specifically, we will (i) discuss the various transport mechanisms by which MPO accumulates into the endothelium of inflamed or diseased arteries, (ii) detail the clinical and basic scientific evidence identifying MPO as a significant cause of endothelial dysfunction and cardiovascular disease, (iii) provide an up-to-date coverage on the different oxidative mechanisms by which MPO can impair endothelial function during cardiovascular disease including an evaluation of the contributions of MPO-catalyzed HOCl production and NO oxidation, and (iv) outline the novel non-enzymatic mechanisms of MPO and their potential contribution to endothelial dysfunction. Finally, we deliver a detailed appraisal of the different pharmacological strategies available for targeting the catalytic and non-catalytic modes-of-action of MPO in order to protect against endothelial dysfunction in cardiovascular disease.
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The Role of Thiocyanate in Modulating Myeloperoxidase Activity during Disease. Int J Mol Sci 2020; 21:ijms21176450. [PMID: 32899436 PMCID: PMC7503669 DOI: 10.3390/ijms21176450] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/31/2020] [Accepted: 09/01/2020] [Indexed: 12/19/2022] Open
Abstract
Thiocyanate (SCN−) is a pseudohalide anion omnipresent across mammals and is particularly concentrated in secretions within the oral cavity, digestive tract and airway. Thiocyanate can outcompete chlorine anions and other halides (F−, Br−, I−) as substrates for myeloperoxidase by undergoing two-electron oxidation with hydrogen peroxide. This forms their respective hypohalous acids (HOX where X− = halides) and in the case of thiocyanate, hypothiocyanous acid (HOSCN), which is also a bactericidal oxidative species involved in the regulation of commensal and pathogenic microflora. Disease may dysregulate redox processes and cause imbalances in the oxidative profile, where typically favoured oxidative species, such as hypochlorous acid (HOCl), result in an overabundance of chlorinated protein residues. As such, the pharmacological capacity of thiocyanate has been recently investigated for its ability to modulate myeloperoxidase activity for HOSCN, a less potent species relative to HOCl, although outcomes vary significantly across different disease models. To date, most studies have focused on therapeutic effects in respiratory and cardiovascular animal models. However, we note other conditions such as rheumatic arthritis where SCN− administration may worsen patient outcomes. Here, we discuss the pathophysiological role of SCN− in diseases where MPO is implicated.
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Vanichkitrungruang S, Chuang CY, Hawkins CL, Davies MJ. Myeloperoxidase-derived damage to human plasma fibronectin: Modulation by protein binding and thiocyanate ions (SCN -). Redox Biol 2020; 36:101641. [PMID: 32863239 PMCID: PMC7378696 DOI: 10.1016/j.redox.2020.101641] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/03/2020] [Accepted: 07/06/2020] [Indexed: 12/29/2022] Open
Abstract
Endothelial cell dysfunction is an early event in cardiovascular disease and atherosclerosis. The origin of this dysfunction is unresolved, but accumulating evidence implicates damaging oxidants, including hypochlorous acid (HOCl), a major oxidant produced by myeloperoxidase (MPO), during chronic inflammation. MPO is released extracellularly by activated leukocytes and binds to extracellular molecules including fibronectin, a major matrix glycoprotein involved in endothelial cell binding. We hypothesized that MPO binding might influence the modifications induced on fibronectin, when compared to reagent HOCl, with this including alterations to the extent of damage to protein side-chains, modified structural integrity, changes to functional domains, and impact on naïve human coronary artery endothelial cell (HCAEC) adhesion and metabolic activity. The effect of increasing concentrations of the alternative MPO substrate thiocyanate (SCN-), which might decrease HOCl formation were also examined. Exposure of fibronectin to MPO/H2O2/Cl- is shown to result in damage to the functionally important cell-binding and heparin-binding fragments, gross structural changes to the protein, and altered HCAEC adhesion and activity. Differences were observed between stoichiometric, and above-stoichiometric MPO concentrations consistent with an effect of MPO binding to fibronectin. In contrast, MPO/H2O2/SCN- induced much less marked changes and limited protein damage. Addition of increasing SCN- concentrations to the MPO/H2O2/Cl- system provided protection, with 20 μM of this anion rescuing damage to functionally-important domains, decreasing chemical modification, and maintaining normal HCAEC behavior. Modulating MPO binding to fibronectin, or enhancing SCN- levels at sites of inflammation may therefore limit MPO-mediated damage, and be of therapeutic value.
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Affiliation(s)
- Siriluck Vanichkitrungruang
- The Heart Research Institute, Newtown, NSW, Australia; Faculty of Medicine, The University of Sydney, NSW, Australia; Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Christine Y Chuang
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Clare L Hawkins
- The Heart Research Institute, Newtown, NSW, Australia; Faculty of Medicine, The University of Sydney, NSW, Australia; Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Michael J Davies
- The Heart Research Institute, Newtown, NSW, Australia; Faculty of Medicine, The University of Sydney, NSW, Australia; Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark.
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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: 17] [Impact Index Per Article: 4.3] [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.
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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.
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Chaikijurajai T, Tang WHW. Myeloperoxidase: a potential therapeutic target for coronary artery disease. Expert Opin Ther Targets 2020; 24:695-705. [PMID: 32336171 PMCID: PMC7387188 DOI: 10.1080/14728222.2020.1762177] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 04/26/2020] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Coronary artery disease (CAD) poses significant morbidity and mortality globally. Despite significant advances in treatment interventions, residual cardiovascular risks remain unchecked. Recent clinical trials have shed light on the potential therapeutic benefits of targeting anti-inflammatory pathways. Myeloperoxidase (MPO) plays an important role in atherosclerotic plaque formation and destabilization of the fibrous cap; both increase the risk of atherosclerotic cardiovascular disease and especially CAD. AREAS COVERED This article examines the role of MPO in the pathogenesis of atherosclerotic CAD and the mechanistic data from several key therapeutic drug targets. There have been numerous interesting studies on prototype compounds that directly or indirectly attenuate the enzymatic activities of MPO, and subsequently exhibit atheroprotective effects; these include aminobenzoic acid hydrazide, ferulic acid derivative (INV-315), thiouracil derivatives (PF-1355 and PF-06282999), 2-thioxanthines derivative (AZM198), triazolopyrimidines, acetaminophen, N-acetyl lysyltyrosylcysteine (KYC), flavonoids, and alternative substrates such as thiocyanate and nitroxide radical. EXPERT OPINION Future investigations must determine if the cardiovascular benefits of direct systemic inhibition of MPO outweigh the risk of immune dysfunction, which may be less likely to arise with alternative substrates or MPO inhibitors that selectively attenuate atherogenic effects of MPO.
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Affiliation(s)
- Thanat Chaikijurajai
- Kaufman Center for Heart Failure Treatment and Recovery, Heart, Vascular and Thoracic Institute, Cleveland Clinic, Cleveland OH, USA
| | - W. H. Wilson Tang
- Kaufman Center for Heart Failure Treatment and Recovery, Heart, Vascular and Thoracic Institute, Cleveland Clinic, Cleveland OH, USA
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