Neutrophil extracellular trap formation and circulating nucleosomes in patients with chronic myeloproliferative neoplasms

Abstract

The mechanisms underlying increased thrombotic risk in chronic myeloproliferative neoplasms (MPN) are incompletely understood. We assessed whether neutrophil extracellular traps (NETs), which promote thrombosis, contribute to the procoagulant state in essential thrombocythemia, polycythemia vera and myelofibrosis (MF) patients. Although MPN neutrophils showed increased basal reactive oxygen species (ROS), enhanced NETosis by unstimulated neutrophils was an infrequent finding, whereas PMA-triggered NETosis was impaired, particularly in MF, due to decreased PMA-triggered ROS production. Elevated circulating nucleosomes were a prominent finding and were higher in patients with advanced disease, which may have potential prognostic implication. Histone-MPO complexes, proposed as specific NET biomarker, were seldomly detected, suggesting NETs may not be the main source of nucleosomes in most patients, whereas their correlation with high LDH points to increased cell turn-over as a plausible origin. Lack of association of nucleosomes or NETs with thrombosis or activation markers does not support their use as predictors of thrombosis although prospective studies in a larger cohort may help define their potential contribution to MPN thrombosis. These results do not provide evidence for relevant in vivo NETosis in MPN patients under steady state conditions, although availability of standardized NET biomarkers may contribute to further research in this field.

GATA1 insufficiencies in primary myelofibrosis and other hematopoietic disorders: consequences for therapy

“…We hypothesized that in myelofibrosis these abnormally high numbers of neutrophils during their interaction with para-apoptotic megakaryocytes would interact with mitochondrial DNA and generate neutrophil presenting extracellular trap (NET) of autologous DNA which would be responsible for antigen presentation and activation of T cells triggering the auto-immune-reactions. Indeed evidence for neutrophil extracellular trap formation in patients with MPN has been recently identified by Oyarzun et al [123]…”

DNA Area and NETosis Analysis (DANA): a High-Throughput Method to Quantify Neutrophil Extracellular Traps in Fluorescent Microscope Images

“…Although each of these methods has strengths, method-specific limitations exist [ 24 ]. One of the most commonly used methods to quantify NETosis is to count by eye the number of cells that have decondensed DNA and/or NET-associated proteins as visualized by fluorescence microscopy [ 25 – 27 ]. While counting NETs and NET-like structures by eye has the advantage of direct visualization, quantifying these images by eye is time consuming, subjective, and can be inconsistent between samples, over time, and across individuals.…”

La thrombose au cours des néoplasies myéloprolifératives

“…En effet, les taux de D-dimères, de complexes thrombine-anti-thrombine (TAT) 8 , ainsi que de fragments F1 Le phénomène d'émission de NET par les polynucléaires neutrophiles a été analysé au cours des néoplasies myéloprolifératives. Dans une première étude, il n'a pas été observé de différence de formation de NET ex vivo par les cellules isolées de patients, même si certains arguments en faveur d'une NETose accrue ont été relatés, notamment une augmentation des taux de nucléosomes circulants [36]. Une seconde étude, parue en 2018, a mis en évidence une augmentation de NETose ex vivo chez les patients et dans un modèle murin de néoplasie.…”