Neutrophil extracellular trap cell death requires both autophagy and superoxide generation

Abstract

Neutrophil extracellular traps (NETs) are extracellular chromatin structures that can trap and degrade microbes. They arise from neutrophils that have activated a cell death program called NET cell death, or NETosis. Activation of NETosis has been shown to involve NADPH oxidase activity, disintegration of the nuclear envelope and most granule membranes, decondensation of nuclear chromatin and formation of NETs. We report that in phorbol myristate acetate (PMA)-stimulated neutrophils, intracellular chromatin decondensation and NET formation follow autophagy and superoxide production, both of which are required to mediate PMA-induced NETosis and occur independently of each other. Neutrophils from patients with chronic granulomatous disease, which lack NADPH oxidase activity, still exhibit PMA-induced autophagy. Conversely, PMA-induced NADPH oxidase activity is not affected by pharmacological inhibition of autophagy. Interestingly, inhibition of either autophagy or NADPH oxidase prevents intracellular chromatin decondensation, which is essential for NETosis and NET formation, and results in cell death characterized by hallmarks of apoptosis. These results indicate that apoptosis might function as a backup program for NETosis when autophagy or NADPH oxidase activity is prevented.

Metabolic effects of fasting on human and mouse blood in vivo

“…Contrary to mice, in which all leukocyte subpopulations exhibited signs of enhanced autophagic flux, only neutrophils from healthy volunteers presented an increased number of LC3B C puncta, in line with previous findings showing autophagy activation in this population. 54,55 In addition, it has been previously demonstrated that detection of autophagy in neutrophils can be used to monitor autophagic flux at the whole body level in the context of pathological settings. 56 At present, the reasons for this discrepancy between mice and humans with respect to autophagy induction in all leukocyte subpopulation and neutrophils only, respectively, are elusive.…”

Molecular definitions of cell death subroutines: recommendations of the Nomenclature Committee on Cell Death 2012

“…161 Netotic cells exhibit massive vacuolization of the cytoplasm, rapid chromatin decondensation and breakdown of both the nuclear and granular membranes, which is required for proper NET formation. 160 Netosis is insensitive to caspase inhibitors and necrostatin-1, 162 further demonstrating that it constitutes a cell death subroutine distinct from apoptosis and regulated necrosis. However, the netotic process can be suppressed by pharmacological inhibition of NADPH oxidase (which is responsible for the oxidative burst occurring during neutrophil activation) or autophagy.…”

High glucose modulates IL‐6 mediated immune homeostasis through impeding neutrophil extracellular trap formation

“…Being a substrate for NADPH oxidase system, reduction in NADPH leads to reduced production of superoxide which is important for NETs formation. Remijesn et al (2011) suggested an intimate interplay between autophagy and NADPH oxidase system which is essential for NETosis [21]. It has been demonstrated that wortmannin and diphenylene iodinium, the inhibitors of PI3K/ autophagy and NADPH oxidase respectively, abrogated phorbol ester (PMA) induced NETosis [21].…”

“…Remijesn et al (2011) suggested an intimate interplay between autophagy and NADPH oxidase system which is essential for NETosis [21]. It has been demonstrated that wortmannin and diphenylene iodinium, the inhibitors of PI3K/ autophagy and NADPH oxidase respectively, abrogated phorbol ester (PMA) induced NETosis [21]. 2-DG has been shown to induce autophagy, NADPH oxidase activity and reactive oxygen species in endothelial cells [22].…”