Hyperoxidation of ether-linked phospholipids accelerates neutrophil extracellular trap formation

Satoshi Yotsumoto,Satoko Arakawa,Rio Ohmura,Yuito Muroi,Masato Tanaka,Makoto Arita,Kosuke Dodo,Mikiko Sodeoka,Naoki Terayama,Tatsuya Chiba,Ryohei Aoyagi,Maki Yoneyama,Megumi Magarisawa,Shigeomi Shimizu

doi:10.1038/s41598-017-15668-z

Abstract

Because neutrophil extracellular trap (NET) formation is involved in the pathology of a wide variety of diseases, NET-regulating compounds are expected to be useful for the therapies of these diseases. In this study, we identified sulfasalazine (SSZ) as a potent enhancer of NET formation both in vitro and in vivo. Although SSZ did not increase the amount of ROS generated, it accelerated the generation of ether-linked oxidized phospholipids, such as PE (18;1e/15-HETE) and PC (16;0e/13-HODE). Trolox, but not 2-ME, effectively suppressed lipid oxidation and NET formation that were induced by SSZ. SSZ is known as a potent inducer of ferroptosis in cancer cells by inhibiting xCT, a component of the cystine transporter. However, we found that SSZ accelerated NET formation in an xCT-independent manner. Structure-activity relationship studies revealed that the sulfapyridine moiety of SSZ plays a central role in enhancing NET formation. Furthermore, we found that two additional sulfonamide and sulfone derivatives possess NET-inducing activity by accelerating lipid oxidation. These results indicate that the hyperoxidation of ether-linked phospholipids is a key mechanism for accelerating NET formation.

Highlights

Because neutrophil extracellular trap (NET) formation is involved in the pathology of a wide variety of diseases, neutrophil extracellular traps (NETs)-regulating compounds are expected to be useful for the therapies of these diseases
Citrullination was inhibited by adding Cl-amidine, a PAD inhibitor, which confirmed that the observed cell death resulted from NETosis (Fig. 1d)
We found that SSZ enhanced E. coli-induced NET formation (Supplemental Fig. 1a)

Summary

Introduction

Because neutrophil extracellular trap (NET) formation is involved in the pathology of a wide variety of diseases, NET-regulating compounds are expected to be useful for the therapies of these diseases. We found that two additional sulfonamide and sulfone derivatives possess NET-inducing activity by accelerating lipid oxidation These results indicate that the hyperoxidation of ether-linked phospholipids is a key mechanism for accelerating NET formation. Activated neutrophils undergo a distinct type of cell death called NETosis that is morphologically distinct from both apoptosis and necrosis[3] This cell death process has been associated with the extracellular release of chromosomal DNA that is coated with histones and proteases and that forms web-like structures[4]. These structures are named neutrophil extracellular traps (NETs), and they play critical roles in the efficient elimination of bacteria by immobilizing bacterial cells. The precise mechanisms underlying each of these events remain obscure

Methods

Results

Conclusion