NMDA receptor modulation of glutamate release in activated neutrophils.

Abstract

BACKGROUND:

Neutrophil depletion improves neurologic outcomes in experimental sepsis/brain injury. We hypothesized that neutrophils may exacerbate neuronal injury through the release of neurotoxic quantities of the neurotransmitter glutamate.

METHODS:

Real-time glutamate release by primary human neutrophils was determined using enzymatic biosensors. Bacterial and direct protein-kinase C (Phorbol 12-myristate 13-acetate; PMA) activation of neutrophils in human whole blood, isolated neutrophils or human cell lines were compared in the presence/absence of N-Methyl-d-aspartic acid receptor (NMDAR) antagonists. Bacterial and direct activation of neutrophils from wild-type and transgenic murine neutrophils deficient in NMDAR-scaffolding proteins were compared using flow cytometry (phagocytosis, reactive oxygen species (ROS) generation) and real-time respirometry (oxygen consumption).

FINDINGS:

Both glutamate and the NMDAR co-agonist d-serine are rapidly released by neutrophils in response to bacterial and PMA-induced activation. Pharmacological NMDAR blockade reduced both the autocrine release of glutamate, d-serine and the respiratory burst by activated primary human neutrophils. A highly specific small-molecule inhibitor ZL006 that limits NMDAR-mediated neuronal injury also reduced ROS by activated neutrophils in a murine model of peritonitis, via uncoupling of the NMDAR GluN2B subunit from its' scaffolding protein, postsynaptic density protein-95 (PSD-95). Genetic ablation of PSD-95 reduced ROS production by activated murine neutrophils. Pharmacological blockade of the NMDAR GluN2B subunit reduced primary human neutrophil activation induced by Pseudomonas fluorescens, a glutamate-secreting Gram-negative bacillus closely related to pathogens that cause hospital-acquired infections.

INTERPRETATION:

These data suggest that release of glutamate by activated neutrophils augments ROS production in an autocrine manner via actions on NMDAR expressed by these cells. FUND: GLA: Academy Medical Sciences/Health Foundation Clinician Scientist. AVG is a Wellcome Trust Senior Research Fellow.

• Authors: Ana Gutierrez Del Arroyo, Anna Hadjihambi, Jenifer Sanchez, Egor Turovsky, Vitaly Kasymov, David Cain, Tom D Nightingale, Simon Lambden, Seth G N Grant, Alexander V Gourine, Gareth L Ackland
• Journal: EBioMedicine (EBioMedicine) Vol. 47 Pg. 457-469 (Sep 2019) ISSN: 2352-3964 [Electronic] Netherlands
• PMID: 31401196 (Publication Type: Journal Article)
• Copyright: Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.

Chemical References

• Biomarkers
• NR2B NMDA receptor
• Reactive Oxygen Species
• Receptors, N-Methyl-D-Aspartate
• Glutamic Acid
• Calcium

Topics

• Animals
• Apoptosis
• Biomarkers
• Calcium (metabolism)
• Cell Line, Tumor
• Disease Models, Animal
• Glutamic Acid (biosynthesis)
• Humans
• Mice
• Neurons (metabolism)
• Neutrophil Activation (immunology)
• Neutrophils (immunology, metabolism)
• Reactive Oxygen Species
• Receptors, N-Methyl-D-Aspartate (metabolism)
• Xenograft Model Antitumor Assays