Toxoplasma gondii induces extracellular traps release in cat neutrophils

• Published in: Experimental parasitology 2019-12, Vol.207, p.107770-107770, Article 107770
• Main Authors: Lacerda, Luciana Carvalho, dos Santos, Jane Lima, Wardini, Amanda Brito, da Silva, Aisla Nascimento, Santos, Andréa Gonçalves, Silva Freire, Herbert Pina, dos Anjos, Danielle Oliveira, Romano, Carla Cristina, Mendes, Érica Araújo, Munhoz, Alexandre Dias
• Format: Article
• Language: English
• Subjects: Cats; Extracellular traps; Neutrophils; Toxoplasma gondii
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1016/j.exppara.2019.107770

Neutrophils respond differently to violations of the body's physiological barriers during infections. Extracellular traps comprise one of the mechanisms used by these cells to reduce the spread of pathogens to neighboring tissues, as well as ensure a high concentration of antimicrobial agents at the site of infection. To date, this innate defense mechanism has not been previously demonstrated in neutrophils of cats exposed to Toxoplasma gondii. The aim of this study was to characterize the in vitro release of neutrophil extracellular traps (NETs) when neutrophils isolated from cats were exposed to T. gondii. First, cellular viability was tested at different time points after parasite exposure. The production of reactive oxygen species (ROS) and lactate dehydrogenase and the amount of extracellular DNA were quantified. In addition, the number of parasites associated with neutrophils was determined, and the observed NETs formed were microscopically characterized. Results showed that (i) in culture, neutrophils isolated from cats presented diminished cellular viability after 4 h of incubation, and when neutrophils were incubated with T. gondii, they displayed cytotoxic effects after 3 h of interaction; (ii) neutrophils were able to release structures composed of DNA and histones, characterized as NETs under optical, immunofluorescence, and electron scanning microscopy, when stimulated with T. gondii; (iii) only 11.4% of neutrophils were able to discharge NETs during 3 h of incubation; however, it was observed through extracellular quantification of DNA that this small number of cells were able to display different behavior compared to a negative control (no parasite) group; (iv) significant differences in ROS production were observed in neutrophils exposed to T. gondii. In conclusion, our results showed that neutrophils isolated from cats exposed to T. gondii release structures composed of DNA and histones, similar to what has already been described in other neutrophil species infected with the parasite. [Display omitted] •Here, we demonstrated that cat neutrophils exposed to T. gondii can release NETs.•Tachyzoites from T. gondii are trapped by extracellular NETs released by cat neutrophils.•Toxoplasma gondii diminishes neutrophils viability after 3 h of interaction.•Cat neutrophils, when in contact with T. gondii, produce ROS after 30 min of interaction.•The amount of extracellular DNA released by neutrophils after parasite interaction was time-dependent.