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C5a impairs phagosomal maturation in the neutrophil through phosphoproteomic remodeling.

Published version
Peer-reviewed

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Authors

Wood, Alexander Jt 
Vassallo, Arlette M 
Ruchaud-Sparagano, Marie-Hélène 
Scott, Jonathan 
Zinnato, Carmelo 

Abstract

Critical illness is accompanied by the release of large amounts of the anaphylotoxin, C5a. C5a suppresses antimicrobial functions of neutrophils which is associated with adverse outcomes. The signaling pathways that mediate C5a-induced neutrophil dysfunction are incompletely understood. Healthy donor neutrophils exposed to purified C5a demonstrated a prolonged defect (7 hours) in phagocytosis of Staphylococcus aureus. Phosphoproteomic profiling of 2712 phosphoproteins identified persistent C5a signaling and selective impairment of phagosomal protein phosphorylation on exposure to S. aureus. Notable proteins included early endosomal marker ZFYVE16 and V-ATPase proton channel component ATPV1G1. An assay of phagosomal acidification demonstrated C5a-induced impairment of phagosomal acidification, which was recapitulated in neutrophils from critically ill patients. Examination of the C5a-impaired protein phosphorylation indicated a role for the PI3K VPS34 in phagosomal maturation. Inhibition of VPS34 impaired neutrophil phagosomal acidification and killing of S. aureus. This study provides a phosphoproteomic assessment of human neutrophil signaling in response to S. aureus and its disruption by C5a, identifying a defect in phagosomal maturation and mechanisms of immune failure in critical illness.

Description

Keywords

Bacterial infections, Complement, Immunology, Infectious disease, Neutrophils, Case-Control Studies, Complement C5a, Critical Illness, Humans, Neutrophils, Phagocytosis, Phagosomes, Phosphoproteins, Proteome, Staphylococcal Infections, Staphylococcus aureus

Journal Title

JCI Insight

Conference Name

Journal ISSN

2379-3708
2379-3708

Volume Title

5

Publisher

American Society for Clinical Investigation
Sponsorship
European Society of Intensive Care Medicine (ESICM) (unknown)
Academy of Medical Sciences (unknown)
Wellcome Trust (205214/Z/16/Z)
AJTW was a Gates Cambridge Scholar supported by the Gates Cambridge Trust from 2015-2018. ACM is supported by a Clinical Research Career Development Fellowship from the Wellcome Trust (WT 2055214/Z/16/Z). Grants to ACM from the Academy of Medical Sciences and European Society for Intensive Care Medicine supported this work. The study was also supported by the National Institute for Health Research (NIHR) Newcastle Biomedical Research Centre (IS-BRC-1215-20001) and the Medical Research Council SHIELD antimicrobial resistance consortium (MR/ N02995X/1)