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Fast and Specific Assessment of the Halogenating Peroxidase Activity in Leukocyte-enriched Blood Samples
Published on: July 28, 2016
Myeloperoxidase: Regulation of Neutrophil Function and Target for Therapy
Salma A Rizo-Téllez1,2, Meriem Sekheri1,2, János G Filep1,2
1Department of Pathology and Cell Biology, University of Montreal, Montreal, QC H3T 1J4, Canada.
Abstract:
Neutrophils, the most abundant white blood cells in humans, are critical for host defense against invading pathogens. Equipped with an array of antimicrobial molecules, neutrophils can eradicate bacteria and clear debris. Among the microbicide proteins is the heme protein myeloperoxidase (MPO), stored in the azurophilic granules, and catalyzes the formation of the chlorinating oxidant HOCl and other oxidants (HOSCN and HOBr). MPO is generally associated with killing trapped bacteria and inflicting collateral tissue damage to the host. However, the characterization of non-enzymatic functions of MPO suggests additional roles for this protein. Indeed, evolving evidence indicates that MPO can directly modulate the function and fate of neutrophils, thereby shaping immunity. These actions include MPO orchestration of neutrophil trafficking, activation, phagocytosis, lifespan, formation of extracellular traps, and MPO-triggered autoimmunity. This review scrutinizes the multifaceted roles of MPO in immunity, focusing on neutrophil-mediated host defense, tissue damage, repair, and autoimmunity. We also discuss novel therapeutic approaches to target MPO activity, expression, or MPO signaling for the treatment of inflammatory and autoimmune diseases.
Insights
Myeloperoxidase (MPO) is a key neutrophil protein with dual roles in immunity. Beyond killing pathogens, MPO influences neutrophil function and can trigger autoimmune diseases, offering new therapeutic targets.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Neutrophils are vital white blood cells for host defense against pathogens.
- Myeloperoxidase (MPO), a heme protein in neutrophils, generates oxidants for antimicrobial activity.
- MPO is traditionally linked to pathogen killing and host tissue damage.
Purpose of the Study:
- To review the multifaceted roles of MPO in immunity.
- To explore MPO's non-enzymatic functions in modulating neutrophil behavior.
- To discuss MPO's involvement in host defense, tissue damage, repair, and autoimmunity.
Main Methods:
- Literature review of MPO's functions in neutrophil biology.
- Analysis of MPO's enzymatic and non-enzymatic activities.
- Examination of MPO's role in immune responses and disease pathogenesis.
Main Results:
- MPO directly regulates neutrophil trafficking, activation, phagocytosis, and lifespan.
- MPO is implicated in the formation of neutrophil extracellular traps.
- Evidence suggests MPO can trigger autoimmunity and influence tissue repair.
Conclusions:
- MPO possesses diverse functions beyond its canonical microbicidal role, significantly shaping innate and adaptive immunity.
- MPO's non-enzymatic functions highlight its critical role in neutrophil fate and immune modulation.
- Targeting MPO offers potential therapeutic strategies for inflammatory and autoimmune diseases.
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