title: Neutrophil-delivered myeloperoxidase dampens the hydrogen peroxide burst after tissue wounding in zebrafish.
abstract: Prompt neutrophil arrival is critical for host defense immediately after injury [1-3]. Following wounding, a hydrogen peroxide (H(2)O(2)) burst generated in injured tissues is the earliest known leukocyte chemoattractant [4]. Generating this tissue-scale H(2)O(2) gradient uses dual oxidase [4] and neutrophils sense H(2)O(2) by a mechanism involving the LYN Src-family kinase [5], but the molecular mechanisms responsible for H(2)O(2) clearance are unknown [6]. Neutrophils carry abundant amounts of myeloperoxidase, an enzyme catalyzing an H(2)O(2)-consuming reaction [7, 8]. We hypothesized that this neutrophil-delivered myeloperoxidase downregulates the high tissue H(2)O(2) concentrations that follow wounding. This was tested in zebrafish using simultaneous fluorophore-based imaging of H(2)O(2) concentrations and leukocytes [4, 9-11] and a new neutrophil-replete but myeloperoxidase-deficient mutant (durif). Leukocyte-depleted zebrafish had an abnormally sustained wound H(2)O(2) burst, indicating that leukocytes themselves were required for H(2)O(2) downregulation. Myeloperoxidase-deficient zebrafish also had abnormally sustained high wound H(2)O(2) concentrations despite similar numbers of arriving neutrophils. A local H(2)O(2)/myeloperoxidase interaction within wound-recruited neutrophils was demonstrated. These data demonstrate that leukocyte-delivered myeloperoxidase cell-autonomously downregulates tissue-generated wound H(2)O(2) gradients in vivo, defining a new requirement for myeloperoxidase during inflammation. Durif provides a new animal model of myeloperoxidase deficiency closely phenocopying the prevalent human disorder [7, 12, 13], offering unique possibilities for investigating its clinical consequences.
authors.affiliation: Cancer and Haematology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia.
authors.forename: Luke
authors.initials: L
authors.lastname: Pase
authors.forename: Judith E
authors.initials: JE
authors.lastname: Layton
authors.forename: Christine
authors.initials: C
authors.lastname: Wittmann
authors.forename: Felix
authors.initials: F
authors.lastname: Ellett
authors.forename: Cameron J
authors.initials: CJ
authors.lastname: Nowell
authors.forename: Constantino Carlos
authors.initials: CC
authors.lastname: Reyes-Aldasoro
authors.forename: Sony
authors.initials: S
authors.lastname: Varma
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Rogers
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Hall
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Keightley
authors.forename: Philip S
authors.initials: PS
authors.lastname: Crosier
authors.forename: Clemens
authors.initials: C
authors.lastname: Grabher
authors.forename: Joan K
authors.initials: JK
authors.lastname: Heath
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Renshaw
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Lieschke
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007962:Leukocytes / Q000201:enzymology; D009154:Mutation; D020556:Neutrophil Infiltration; D009504:Neutrophils / Q000201:enzymology*; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism*; D015027:Zebrafish / Q000235:genetics / Q000293:injuries* / Q000378:metabolism
chemical_list: D006861:Hydrogen Peroxide; D009195:Peroxidase