Mouse neutrophils release extracellular traps in response toNaegleria fowleri

Summary Naegleria fowleri is a free‐living amoeba, which is able to infect humans through the nasal mucosa causing a disease in the central nervous system known as primary amoebic meningoencephalitis ( PAM ). Polymorphonuclear cells ( PMN s) play a critical role in the early phase of N fowleri infection. Recently, a new biological defence mechanism called neutrophil extracellular traps ( NET s) has been attracting attention. These structures represent an important strategy to immobilize and kill invading microorganisms. In this work, we evaluate the capacity of N fowleri to induce the NET s release by PMN s cells in mice in vitro and in vivo. In vitro: Neutrophils from bone marrow were cocultured with N fowleri trophozoites. In vivo: we employed a mouse model of PAM . We evaluated DNA , histone and myeloperoxidase ( MPO ) and the formation of NET s by confocal microscopy. Our results showed N fowleri induce both NET s and MPO release by PMN s cells in mice after trophozoite exposure, which increased through time, in vitro and in vivo. These results demonstrate that NET s are somehow associated with the amoebas. We suggest PMN s release their traps trying to avoid N fowleri attachment at the apical side of the nasal epithelium.