TY - JOUR

T1 - New insight into the composition of extracellular traps released by macrophages exposed to different types of inducers

AU - Jensen, Mathias

AU - Thorsen, Nicoline W.

AU - Hallberg, Line A.E.

AU - Hägglund, Per

AU - Hawkins, Clare L.

N1 - Publisher Copyright: © 2023 The Authors

PY - 2023

Y1 - 2023

N2 - Neutrophil extracellular trap (NET) release plays a key role in many chronic disease settings, including atherosclerosis. They are critical to innate immune defence, but also contribute to disease by promoting thrombosis and inflammation. Macrophages are known to release extracellular traps or “METs”, but their composition and role in pathological processes are less well defined. In this study, we examined MET release from human THP-1 macrophages exposed to model inflammatory and pathogenic stimuli, including tumour necrosis factor α (TNFα), hypochlorous acid (HOCl) and nigericin. In each case, there was release of DNA from the macrophages, as visualized by fluorescence microscopy with the cell impermeable DNA binding dye SYTOX green, consistent with MET formation. Proteomic analysis on METs released from macrophages exposed to TNFα and nigericin reveals that they are composed of linker and core histones, together with a range of cytosolic and mitochondrial proteins. These include proteins involved in DNA binding, stress responses, cytoskeletal organisation, metabolism, inflammation, anti-microbial activity, and calcium binding. Quinone oxidoreductase in particular, was highly abundant in all METs but has not been reported previously in NETs. Moreover, there was an absence of proteases in METs in contrast to NETs. Some of the MET histones, contained post-translational modifications, including acetylation and methylation of Lys but not citrullination of Arg. These data provide new insight into the potential implications of MET formation in vivo and their contributions to immune defence and pathology.

AB - Neutrophil extracellular trap (NET) release plays a key role in many chronic disease settings, including atherosclerosis. They are critical to innate immune defence, but also contribute to disease by promoting thrombosis and inflammation. Macrophages are known to release extracellular traps or “METs”, but their composition and role in pathological processes are less well defined. In this study, we examined MET release from human THP-1 macrophages exposed to model inflammatory and pathogenic stimuli, including tumour necrosis factor α (TNFα), hypochlorous acid (HOCl) and nigericin. In each case, there was release of DNA from the macrophages, as visualized by fluorescence microscopy with the cell impermeable DNA binding dye SYTOX green, consistent with MET formation. Proteomic analysis on METs released from macrophages exposed to TNFα and nigericin reveals that they are composed of linker and core histones, together with a range of cytosolic and mitochondrial proteins. These include proteins involved in DNA binding, stress responses, cytoskeletal organisation, metabolism, inflammation, anti-microbial activity, and calcium binding. Quinone oxidoreductase in particular, was highly abundant in all METs but has not been reported previously in NETs. Moreover, there was an absence of proteases in METs in contrast to NETs. Some of the MET histones, contained post-translational modifications, including acetylation and methylation of Lys but not citrullination of Arg. These data provide new insight into the potential implications of MET formation in vivo and their contributions to immune defence and pathology.

KW - Atherosclerosis

KW - DNA

KW - Immunity

KW - Inflammation

KW - Macrophage

KW - Proteomics

UR - http://www.scopus.com/inward/record.url?scp=85151406353&partnerID=8YFLogxK

U2 - 10.1016/j.freeradbiomed.2023.03.025

DO - 10.1016/j.freeradbiomed.2023.03.025

M3 - Journal article

C2 - 36990299

AN - SCOPUS:85151406353

VL - 202

SP - 97

EP - 109

JO - Free Radical Biology & Medicine

JF - Free Radical Biology & Medicine

SN - 0891-5849

ER -