IFN-γ-NOD2/IL-5-FCGR axis enhances eosinophil extracellular trap formation in allergic bronchopulmonary aspergillosis/mycosis.

BACKGROUND

Allergic bronchopulmonary aspergillosis/mycosis (ABPA/M) is characterized by systemic eosinophilia and eosinophil-rich mucus plugs, but mechanisms programming eosinophil pathogenicity remain unclear.

OBJECTIVE

We aim to define eosinophil activation programs and upstream signals that promote extracellular trap formation in ABPA/M.

METHODS

We performed multi-omics analyses (RNA sequencing and proteomics) of blood eosinophils from healthy participants, patients with eosinophilic asthma, and patients with ABPA/M. Surface-marker profiles were compared between blood and airway eosinophils from patients with ABPA/M. In vitro stimulation assays using IFN-γ, IL-5, and a nucleotide-binding oligomerization domain-containing 2 (NOD2) ligand were combined with multi-omics readouts and functional evaluation of IgG cross-linking-induced eosinophil extracellular trap formation.

RESULTS

Multi-omics profiling identified activation patterns consistent with IFN-γ and IL-5 signaling in ABPA/M blood eosinophils. ICAM-1 was upregulated on both blood and airway eosinophils, whereas PD-L1 upregulation was specific to airway eosinophils. PD-L1 induction required combined stimulation with IFN-γ and a NOD2 ligand, but not IL-5. Under IFN-γ plus NOD2 ligand stimulation, eosinophils exhibited inflammatory remodeling, including increased Fc gamma receptor expression. Functionally, pretreatment with IFN-γ and a NOD2 ligand enhanced IgG cross-linking-induced extracellular trap formation in an NADPH oxidase-dependent manner and required lymphocyte function-associated antigen 1 interactions with ICAM-1. Combined stimulation with IFN-γ and IL-5 similarly augmented extracellular trap formation.

CONCLUSION

ABPA/M eosinophils are shaped by mixed inflammatory cues, in which IFN-γ cooperates with fungal-sensing signals or IL-5 to enhance Fc gamma receptor-linked, IgG-triggered extracellular trap formation, potentially contributing to mucus plugging.