Besnoitia besnoiti tachyzoites induce monocyte extracellular trap formation
- 560 Downloads
Extracellular trap (ET) formation has been demonstrated as an important novel effector mechanism of polymorphonuclear neutrophils (PMN), eosinophils, mast cells and macrophages acting extracellularly against pathogens. In the present study, we show that tachyzoites of the emerging apicomplexan parasite Besnoitia besnoiti, that have recently been reported as potent inducers of PMN-derived ETosis, also trigger the release of ETs in an additional cell type, namely in monocytes. Fluorescence illustrations as well as scanning electron microscopy analyses (SEM) showed monocyte-promoted ET formation to be rapidly induced upon exposure to viable tachyzoites of B. besnoiti. Classical characteristics of ETs were confirmed by the co-localization of extracellular DNA with histones (H3) or myeloperoxidase (MPO) in parasite-entrapping structures. Monocyte-derived ETs were efficiently abolished by DNase I treatment and significantly reduced by treatments with inhibitors of MPO and NADPH oxidase, thus strengthening the key roles of reactive oxygen species (ROS) and MPO in monocyte ET formation. For comparative reasons, we additionally tested sporozoite stages of the closely related parasite Eimeria bovis for their capacity to induce monocyte-derived ETs and showed that these stages indeed induce ETs. To our best knowledge, we here report for the first time on monocyte ETs against the apicomplexan parasites B. besnoiti and E. bovis. Our results indicate that monocyte-triggered ETs may represent an important effector mechanism of the host early innate immune response against B. besnoiti and add a new cell type to the list of cells capable to release ETs.
KeywordsBesnoitia besnoiti Eimeria bovis Extracellular traps Monocytes
We would like to acknowledge Brigitte Hofmann, Davinia Pérez and Klaus Becker for their excellent work in cell culture, parasite preparation and monocyte isolation as well as the collection of blood samples. We extend further our thanks to Gerd Magdowski, Institute of Anatomy and Cell Biology, Justus Liebig University, for his excellent contribution in scanning electron microscopy analyses. TMC is a PhD student of the International Giessen Graduate Centre for Life Sciences (GGL) at the JLU Giessen, Germany, and LMRS is a PhD student (grant BD 72032/2010) of the Foundation for Science and Technology (FCT; Portugal).
- EFSA (2010) Bovine Besnoitiosis: An emerging disease in Europe EFSA Journal 8Google Scholar
- Gentile A, Militerno G, Schares G, Nanni A, Testoni S, Bassi P, Gollnick NS (2012) Evidence for bovine besnoitiosis being endemic in Italy-first in vitro isolation of Besnoitia besnoiti from cattle born in Italy. Vet Parasitol 184:108–115. doi: 10.1016/j.vetpar.2011.09.014 PubMedCrossRefGoogle Scholar
- Guimarães-Costa AB, Nascimento MT, Froment GS, Soares RP, Morgado FN, Conceicao-Silva F, Saraiva EM (2009) Leishmania amazonensis promastigotes induce and are killed by neutrophil extracellular traps. Proc Natl Acad Sci USA 106:6748–6753. doi: 10.1073/pnas.0900226106 PubMedCrossRefPubMedCentralGoogle Scholar
- Hermosilla C, Barbisch B, Heise A, Kowalik S, Zahner H (2002) Development of Eimeria bovis in vitro: suitability of several bovine, human and porcine endothelial cell lines, bovine fetal gastrointestinal, Madin-Darby bovine kidney (MDBK) and African green monkey kidney (VERO) cells. Parasitol Res 88:301–307PubMedCrossRefGoogle Scholar
- Hermosilla C, Muñoz-Caro T, Silva LMR, Ruiz A, Taubert A (2014) The intriguing host innate immune response: novel anti-parasitic defence by neutrophil extracellular traps. Parasitology:1–10. doi: 10.1017/S0031182014000316
- Jacquiet P et al. (2009) Besnoitiose bovine : enquêtes épidémiologiques dans le Sud-Ouest de la France. Recueil des Journées Nationales :8Google Scholar
- Ueno N, Harker KS, Clarke EV, McWhorter FY, Liu WF, Tenner AJ, Lodoen MB (2014) Real-time imaging of Toxoplasma-infected human monocytes under fluidic shear stress reveals rapid translocation of intracellular parasites across endothelial barriers. Cell Microbiol 16:580–595. doi: 10.1111/cmi.12239 PubMedCrossRefGoogle Scholar