Curr. Protoc. Immunol. 102:12.14.1-12.14.30. © 2013 by John Wiley & Sons, Inc. “
“Neutrophil extracellular traps (NETs) comprise extracellular chromatin and granule protein complexes that immobilize and kill bacteria. NET release represents a recently discovered, novel anti-microbial strategy regulated learn more non-exclusively by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase generation of reactive oxygen intermediates (ROIs), particularly hydrogen peroxide. This study

aimed to characterize the role of ROIs in the process of NET release and to identify the dominant ROI trigger. We employed various enzymes, inhibitors and ROIs to record their effect fluorometrically on in vitro NET release by human peripheral blood neutrophils. Treatment with exogenous superoxide dismutase (SOD) supported the established link between hydrogen peroxide and NET production. However, treatment with myeloperoxidase inhibitors

and direct addition of hypochlorous acid (HOCl; generated in situ from sodium hypochlorite) established that HOCl was a necessary and sufficient ROI for NET release. This was confirmed by the ability of HOCl to stimulate NET release in chronic granulomatous disease (CGD) patient neutrophils which, due to the lack of a functional NADPH oxidase, also lack the capacity for NET release in response to classical stimuli. Moreover, the exogenous addition of taurine, abundantly present within the neutrophil cytosol, abrogated NET production stimulated by phorbol myristate acetate (PMA) and HOCl, providing a novel mode of cytoprotection by taurine against oxidative stress by taurine. As key effector cells of both innate C646 datasheet and acquired immune responses, polymorphonuclear leucocytes (neutrophils) possess intracellular and extracellular killing mechanisms for elimination of pathogenic bacteria. Neutrophils are also capable of switching to a non-phlogistic phenotype during the active resolution

phase of acute inflammation [1]. In addition to the classic killing mechanisms of phagocytosis and extracellular degranulation of proteases and reactive oxygen species (ROS), neutrophils are now known to extrude their decondensed nuclear chromatin complexed with granule-derived anti-microbial peptides into the extracellular space. The released structures Levetiracetam are known as neutrophil extracellular traps (NETs) and function to both immobilize and kill microbes [2]. The release of NETs has been proposed to arise as a form of programmed cell death termed ‘NETosis’, which is distinct from apoptosis and necrosis [3,4]. Research has also demonstrated NET release from viable eosinophils [5] and viable neutrophils, where short-term stimulation releases mitochondrial NET-DNA rather than nuclear DNA and neutrophil life expectancy was unaffected [6]. NET release mechanisms demonstrate variance according to the robustness of the stimulus and the cell type investigated.