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Myeloperoxidase

About: Myeloperoxidase is a research topic. Over the lifetime, 7198 publications have been published within this topic receiving 301749 citations. The topic is also known as: uniprot:P05164 & myeloperoxidase.


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Journal ArticleDOI
TL;DR: It is demonstrated that MPO can be used as a marker for skin neutrophil content: it is recoverable from skin in soluble form, and is directly related to neutrophIL number.

3,298 citations

Journal ArticleDOI
TL;DR: It is concluded that the MPO system plays an important role in the microbicidal activity of phagocytes and the role of theMPO system in tissue injury.
Abstract: Neutrophilic polymorphonuclear leukocytes (neutrophils) are highly specialized for their primary function, the phagocytosis and destruction of microorganisms. When coated with opsonins (generally complement and/or antibody), microorganisms bind to specific receptors on the surface of the phagocyte and invagination of the cell membrane occurs with the incorporation of the microorganism into an intracellular phagosome. There follows a burst of oxygen consumption, and much, if not all, of the extra oxygen consumed is converted to highly reactive oxygen species. In addition, the cytoplasmic granules discharge their contents into the phagosome, and death of the ingested microorganism soon follows. Among the antimicrobial systems formed in the phagosome is one consisting of myeloperoxidase (MPO), released into the phagosome during the degranulation process, hydrogen peroxide (H2O2), formed by the respiratory burst and a halide, particularly chloride. The initial product of the MPO-H2O2-chloride system is hypochlorous acid, and subsequent formation of chlorine, chloramines, hydroxyl radicals, singlet oxygen, and ozone has been proposed. These same toxic agents can be released to the outside of the cell, where they may attack normal tissue and thus contribute to the pathogenesis of disease. This review will consider the potential sources of H2O2 for the MPO-H2O2-halide system; the toxic products of the MPO system; the evidence for MPO involvement in the microbicidal activity of neutrophils; the involvement of MPO-independent antimicrobial systems; and the role of the MPO system in tissue injury. It is concluded that the MPO system plays an important role in the microbicidal activity of phagocytes.

2,070 citations

Journal ArticleDOI
TL;DR: In this paper, an assay was devised to quantitate acute intestinal inflammation based on the assessment of myeloperoxidase activity, an enzyme found in neutrophils and, in much smaller quantities, in monocytes and macrophages.

1,663 citations

Journal ArticleDOI
TL;DR: Neutrophil elastase escapes azurophilic granules, translocates to the nucleus, and degrades histones to promote chromatin decondensation necessary for NET formation.
Abstract: Neutrophils release decondensed chromatin termed neutrophil extracellular traps (NETs) to trap and kill pathogens extracellularly. Reactive oxygen species are required to initiate NET formation but the downstream molecular mechanism is unknown. We show that upon activation, neutrophil elastase (NE) escapes from azurophilic granules and translocates to the nucleus, where it partially degrades specific histones, promoting chromatin decondensation. Subsequently, myeloperoxidase synergizes with NE in driving chromatin decondensation independent of its enzymatic activity. Accordingly, NE knockout mice do not form NETs in a pulmonary model of Klebsiella pneumoniae infection, which suggests that this defect may contribute to the immune deficiency of these mice. This mechanism provides for a novel function for serine proteases and highly charged granular proteins in the regulation of chromatin density, and reveals that the oxidative burst induces a selective release of granular proteins into the cytoplasm through an unknown mechanism.

1,454 citations

Journal ArticleDOI
22 Jan 1998-Nature
TL;DR: The data reveal that NO2− may regulate inflammatory processes through oxidative mechanisms, perhaps by contributing to the tyrosine nitration and chlorination observed in vivo.
Abstract: Nitric oxide (.NO) plays a central role in the pathogenesis of diverse inflammatory and infectious disorders. The toxicity of .NO is thought to be engendered, in part, by its reaction with superoxide (O2.-), yielding the potent oxidant peroxynitrite (ONOO-). However, evidence for a role of ONOO- in vivo is based largely upon detection of 3-nitrotyrosine in injured tissues. We have recently demonstrated that nitrite (NO2-), a major end-product of .NO metabolism, readily promotes tyrosine nitration through formation of nitryl chloride (NO2Cl) and nitrogen dioxide (.NO2) by reaction with the inflammatory mediators hypochlorous acid (HOCl) or myeloperoxidase. We now show that activated human polymorphonuclear neutrophils convert NO2- into NO2Cl and .NO2 through myeloperoxidase-dependent pathways. Polymorphonuclear neutrophil-mediated nitration and chlorination of tyrosine residues or 4-hydroxyphenylacetic acid is enhanced by addition of NO2- or by fluxes of .NO. Addition of 15NO2- led to 15N enrichment of nitrated phenolic substrates, confirming its role in polymorphonuclear neutrophil-mediated nitration reactions. Polymorphonuclear neutrophil-mediated inactivation of endothelial cell angiotensin-converting enzyme was exacerbated by NO2-, illustrating the physiological significance of these reaction pathways to cellular dysfunction. Our data reveal that NO2- may regulate inflammatory processes through oxidative mechanisms, perhaps by contributing to the tyrosine nitration and chlorination observed in vivo.

1,450 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023312
2022648
2021293
2020277
2019269
2018291