In Vivo Imaging of Neutrophil Extracellular Traps (NETs): Visualization Methods and Outcomes

Abstract

Neutrophils comprise the first line of innate immune defense during a host-pathogen interaction. ey attack microorganisms directly through three different methods, of which, phagocytosis and degranulation have been known and well-studied for decades. e formation of neutrophil extracellular traps (NETs) is the third and unique method, which was unveiled in 2004. Since then, many studies on NETs have been carried out. However, only few have successfully demonstrated the activity of NETs in vivo. Results of the in vivo studies on NETs have strengthened our understanding of their role in different situations. is review highlights the main in vivo studies, which have contributed in extending our understanding of the role of NETs during infections and diseases, thus indicating their advantages and limitations.

Neutrophil Extracellular Traps in Inflammatory Bowel Disease: Pathogenic Mechanisms and Clinical Translation

“…Ideal methodology would combine the use of sandwich enzyme-linked immunosorbent assays for blood work, targeting DNA-MPO/citH3/NE complexes, 59 colocalization studies in tissue using immunohistochemistry, 60 intravital microscopy, and live cell imaging. 61,62 2. For NET formation studies, neutrophils must be isolated with an appreciation of the ability of calcium, magnesium, and chelators to alter NET formation capacity.…”

Multiple Origins of Extracellular DNA Traps

“…These NETs are more resistant to the action of DNases ( 64 ). In the formation of NETs by the independent way of NADPH oxidase, ROS come from the mitochondria and the blockade of MPO does not inhibit the extrusion of NETs, although it is partially dependent on MLKL ( 61 , 65 ). Processes such as vesiculation, DNA decondensation, release of nuclear DNA into the cytoplasm and expulsion of extracellular DNA can be observed in this pathway ( 66 ).…”

“…Extrusion of NETs occurs in a manner dependent upon the MPO and the necroptotic cell death effector “mixed lineage kinase domain-like” (MLKL). The formation time of NETs in this pathway is lengthy (2–3 h) ( 61 ).…”

Neutrophils, NETs, NETosis and their paradoxical roles in COVID-19

“…Neutrophils reaching the circulation are: equipped with the proteins that are required to kill microorganisms and directed by cytokines into the infected cells [15]. In response to infection, polymorphonuclear leukocytes (PMNLs) are recruited to the sites of infection and they employ the following 3 major strategies to ight various microbes: phagocytosis, degranulation, and NETosis [16][17][18].…”