Iron excess affects release of neutrophil extracellular traps and reactive oxygen species but does not influence other functions of neutrophils

Abstract

Neutrophils apply several antimicrobial strategies including degranulation, phagocytosis, the generation of reactive oxygen species (ROS) and the release of neutrophil extracellular traps (NETs) to fight pathogens. Iron is considered to be an invaluable constituent of host immune defense and plays a dual role in immunity. It is a well-known component of antimicrobial proteins and is a necessary microelement for pathogen survival. The aim of this study was to broaden the knowledge regarding the impact of iron on the function of neutrophils. Neutrophils from healthy blood donors and patients with mild irondeficiency anemia and HL-60 cells differentiated toward granulocyte-like cells were incubated with Fe 2+ , Fe 3+ or holo-transferrin (holo-Tf). Moreover, we isolated murine neutrophils of HFE gene knockout (KO) mice and mice fed irondeficient, iron-equivalent and high-iron diets. We analyzed the release of NETs, phagocytosis, degranulation of azurophilic granules, ROS release, bactericidal activity of granulocytes against Escherichia coli and neutrophil elastase (NE) activity. We show that holo-Tf inhibits the release of NETs stimulated by phorbol 12-myristate 13-acetate by inhibiting NE activity. Studies performed in mice models reveal that iron overload inhibits the release of NETs and ROS production in neutrophils isolated from HFE KO mice and mice fed a high-iron diet. No impact of a low-iron diet on neutrophil phagocytosis, ROS production or release of NETs was observed. Our study underscores the physiological significance of iron in neutrophil function, specifically in the release of NETs.

Proteomics unite traditional toxicological assessment methods to evaluate the toxicity of iron oxide nanoparticles

“…Studies investigating nanomaterial clearance by the immune system indicate that NETs act as physical barriers for nanoparticles (Bartneck et al, 2009). Consistently, Kuźmicka et al demonstrated that excess iron increased the release of NETs and reactive oxygen species (Kuzmicka et al, 2022). Therefore, the observed increases in the leucocyte count and neutrophil percentage indicate a primary immune response and a potential mechanism of clearance of the IONPs from the systemic circulation after intravenous administration.…”

Photothermal Nanozyme‐Based Microneedle Patch against Refractory Bacterial Biofilm Infection via Iron‐Actuated Janus Ion Therapy

“…[ 35 ] As such, high levels of intracellular iron can inhibit NETs formation. [ 36 ] To observe the effect of FGO@MN on NETs formation, we performed immunofluorescence staining of treated neutrophils after LPS stimulation using CLSM. Specifically, Ly‐6G is a marker for neutrophils and Cit‐H3 is a biomarker for NETs.…”