Neutrophil Extracellular Trap Formation and Deoxyribonuclease I Activity in Patients with Otitis Media with Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

Abstract

<b><i>Introduction:</i></b> No previous studies have evaluated the levels of neutrophil extracellular trap (NET) remnants or the importance of deoxyribonuclease (DNase) I activity based on the disease activity of otitis media with antineutrophil cytoplasmic antibody-associated vasculitis (OMAAV). The aim of this study was to explore the formation of NETs in the middle ear of patients with OMAAV during the onset and remission phases of the disease, with a particular focus on the relationships between the quantifiable levels of NET remnants and DNase I activity. <b><i>Methods:</i></b> OMAAV patients were eligible for inclusion. Patients with otitis media with effusion (OME) were examined as controls. The levels of cell-free deoxyribonucleic acid (DNA), citrullinated-histone H3 (cit-H3)-DNA complex, and myeloperoxidase (MPO)-DNA complex were quantified using an enzyme-linked immunosorbent assay. DNase I activity was measured using a fluorometric method. <b><i>Results:</i></b> The quantifiable levels of cell-free DNA, cit-H3-DNA complex, and MPO-DNA complex in the middle ear lavage of patients with OMAAV at onset were significantly higher than those in patients with OMAAV at remission and in patients with OME. DNase I activity in the patients with OMAAV at onset was significantly lower than those in patients with OMAAV at remission and OME and was negatively correlated with the level of MPO-DNA complex. <b><i>Conclusions:</i></b> This study suggests that NET remnants and DNase I activity may be potentially useful biomarkers for the diagnosis and disease activity of OMAAV.