title: Monosodium urate crystals induce extracellular DNA traps in neutrophils, eosinophils, and basophils but not in mononuclear cells.
abstract: Neutrophil extracellular traps (NETs) are fibers of extracellular DNA released from neutrophils due to overwhelming phagocytic stimuli. The function of NETs is to trap and kill microbes to avoid spreading of potential pathogens. NETs are formed after encounter with various gram-positive and -negative bacteria but also in response to mediators causing sterile inflammation like interleukin-8 (IL-8), tumor necrosis factor (TNF), and phorbol myristate acetate (PMA). Here we show the formation of NETs (NETting) in response to monosodium urate (MSU) crystals as further model for sterile inflammation. We identified monocytes, neutrophils, and eosinophils as MSU phagocytosing cells. Basophils did not take up the crystals, instead they upregulated their activation marker CD203c after contact with MSU. Nevertheless, MSU crystals induced extracellular trap formation also in basophils, like in eosinophils and neutrophils, which phagocytose the crystals. In contrast, monocytes do not form NETs despite uptake of the MSU crystals. In contrast to the canonical stimuli like bacteria and PMA, MSU-induced NETosis was not abrogated by plasma. Our data show that MSU crystals induce extracellular DNA trap formation in all three granulocytes lineages (NETs, EETs, and BETs) but not in monocytes, and DNA externalization does not necessitate the uptake of the crystals.
authors.affiliation: Department of Internal Medicine 3, Institute for Clinical Immunology, Friedrich-Alexander University Erlangen-Nuremberg Erlangen, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Schorn
authors.forename: Christina
authors.initials: C
authors.lastname: Janko
authors.forename: Melanie
authors.initials: M
authors.lastname: Latzko
authors.forename: Ricardo
authors.initials: R
authors.lastname: Chaurio
authors.forename: Georg
authors.initials: G
authors.lastname: Schett
authors.forename: Martin
authors.initials: M
authors.lastname: Herrmann