Neutrophil activation and circulating neutrophil extracellular traps are increased in venous thromboembolism patients for at least one year after the clinical event

Abstract

Neutrophil activation and neutrophil extracellular traps (NETs) have been associated with the pathogenesis of venous thromboembolism (VTE). Considering VTE-associated chronic sequelae, which suggest that some pathological mechanisms remain after the acute episode, we investigated whether neutrophil activation is increased in patients with a prior VTE at least one year before this investigation. Thirty-seven patients with prior VTE and 37 individuals with no history of VTE were included. Neutrophil activity was evaluated by the expression of the adhesive molecule activation-specific epitopes LFA-1 (CD11a) and MAC-1 (CD11b), chemotaxis, reactive oxygen species (ROS) and by MPO-DNA complexes as markers of NETs. The adhesive molecules sICAM-1 and sVCAM-1, involved in the cross talk between neutrophil and endothelial cells, were also evaluated. Patient neutrophils presented increased CD11a expression before and after TNF-α stimulus, whereas increased CD11b expression was observed only after TNF-α stimulus, as compared to controls. Neutrophil chemotaxis on both, basal state and after IL-8 stimulus, on circulating levels of sICAM-1 and sVCAM-1, and on MPO-DNA complexes were also increased in VTE patients. ROS release was similar between patients and controls. This is, to our knowledge, the first study to investigate neutrophil inflammatory activity in VTE patients a long period after an acute event (approximately 2 years). The results showed altered neutrophil activation patterns in these patients. While activated neutrophils can cause endothelial activation and injury, the activated endothelium can induce the release of NETs with consequent endothelial cytotoxicity, creating a vicious cycle of activation between neutrophils and endothelium that can lead to thrombosis. Graphical abstract VTE patients (approximately 2 years after the clinical event) present an altered neutrophil activation state evidenced by increased activity of the LFA-1 and Mac-1 adhesive molecules, as well as increased chemotaxis and circulating levels of NETs remnants. Circulating levels of ICAM-1 and VCAM-1, which are endothelial adhesive molecules, are also increased in VTE patients, suggesting not only an exacerbated endothelial activation and dysfunction, but also an interaction of the neutrophil adhesive molecules with their endothelial ligands, favoring the migration process of neutrophil.

Fundamentals in Covid-19-Associated Thrombosis: Molecular and Cellular Aspects

“…Indeed, a higher level of D-dimer was detected in patients recovering from COVID-19, while other coagulation and inflammation markers were at basal levels (237). Besides the aforementioned factors, the assessment of NET markers may also be beneficial in the management of long-term post-COVID-19 patients since it was demonstrated that circulating NET remnants are increased in individuals up to 2 years after the diagnosis of venous thromboembolism (238). Although less is known about the long-term consequences, there is evidence that endothelial activation, low-grade inflammation, and hypercoagulability may persist in post-acute COVID-19.…”

Platelet–Neutrophil Crosstalk in Thrombosis

“…Additionally, neutrophils significantly contribute to the development of DVT through their ability to release highly thrombotic NETs [ 44 , 47 , 107 ]. During VTE and for at least 1 year post event, patients exhibit increased levels of activated neutrophils and circulating MPO-DNA complexes [ 108 ]. In mice, depleting neutrophils, administering DNase for the dissolution of NETs or inhibiting the process of NET formation by knocking out Pad4 , have all been associated with DVT protection [ 10 , 44 , 107 , 109 ].…”

Neutrophil extracellular traps mediate deep vein thrombosis: from mechanism to therapy

“…Endothelial cells directly modulate neutrophil activity through the release of cytokines such as IL-1β, IL-8, and ROS, thereby accelerating the formation of NETs and regulating platelet function ( 104 , 105 ). Meanwhile, NETs activate endothelial cells, promote the production of TXA2 and P-selectin by platelets, activate vascular cell adhesion molecule 1 (VCAM-1) and intracellular adhesion molecule 1 (ICAM-1), facilitate neutrophil migration, and enhance neutrophil-endothelial cell interactions ( 104 , 106 ). One study found that this may be associated with the Gab2 protein (Grb-associated binder to adaptor signaling protein) pathway ( 107 ).…”