Neutrophil extracellular traps in thrombi retrieved during interventional treatment of ischemic arterial diseases

Abstract

Highlights-Neutrophil extracellular traps (NETs) modify the structure and stability of fibrin.-NET content of thrombi varies at different locations (brain, heart, peripheral arteries).-DNA and histones in thrombi correlate with age and systemic inflammatory markers.-The amount of fibrin is similar at all examined arterial locations.-Thicker fibrin fibers are formed in coronaries than in brain and peripheral arteries. 3 Abstract Introduction-The ultrastructure and cellular composition of thrombi has a profound effect on the outcome of acute ischemic stroke (AIS), coronary (CAD) and peripheral artery disease (PAD). Activated neutrophils release a web-like structure composed mainly of DNA and citrullinated histones, called neutrophil extracellular traps (NET) that modify the stability and lysability of fibrin. Here, we investigated the NET-related structural features of thrombi retrieved from different arterial localizations and their interrelations with routinely available clinical data. Patients and methods-Thrombi extracted from AIS (n=78), CAD (n=66) or PAD (n=64) patients were processed for scanning electron microscopy, (immune)stained for fibrin, citrullinated histone H3 (cH3) and extracellular DNA. Fibrin fiber diameter, cellular components, DNA and cH3 were measured and analyzed in relation to clinical parameters. Results-DNA was least present in AIS thrombi showing a 2.5-fold lower DNA/fibrin ratio than PAD, whereas cH3 antigen was unvaryingly present at all locations. The NET content of thrombi correlated parabolically with systemic inflammatory markers and positively with patients' age. The median platelet content was lower in PAD (2.2%) than in either AIS (3.9%) or CAD (3.1%) and thrombi from smokers contained less platelets than non-smokers. Fibrin fibers were significantly thicker in male patients with CAD (median fiber diameter 76.3 nm) compared to AIS (64.1 nm) or PAD (62.1 nm) and their diameter correlated parabolically with systemic inflammatory markers.Conclusions-The observed NET-related variations in thrombus structure shed light on novel determinants of thrombus stability that eventually affect both the spontaneous progress and therapeutic outcome of ischemic arterial diseases.

Surrogate Markers of Neutrophil Extracellular Trap Formation are Associated with Ischemic Outcomes and Platelet Activation after Peripheral Angioplasty and Stenting

“…Markers of NETs were previously detected at the site of thrombus formation and plaque rupture in different patient cohorts [8,[34][35][36] including patients with PAD [11]. However, our study is the first to show a significant association between surrogate markers of NET formation and ischemic outcomes in patients with stable PAD after infrainguinal angioplasty and stenting.…”

“…Neutrophil extracellular traps (NETs) are DNA-and histone-containing structures released by neutrophils, and were originally shown to fight bacteria [5]. Recently, NETs and their components were identified in atherosclerotic plaques and arterial thrombi of mice and humans [6][7][8][9][10] as well as in thrombi of patients with PAD [11].…”

Networks that stop the flow: A fresh look at fibrin and neutrophil extracellular traps

“…NETs are abundant in human venous thrombus samples, particularly those in the organizing stages [28]. Similarly, arterial thrombi from patients who suffered heart attack [29,30], stroke [31], or peripheral arterial disease [32] contain NETs (Fig. 1).…”

Polyanions in Coagulation and Thrombosis: Focus on Polyphosphate and Neutrophils Extracellular Traps

“…infusion of DNase interferes with thrombus formation (49,56). NETs are also enriched in human venous and arterial thrombi of patients who suffered from a heart attack (57), stroke (58), and peripheral vascular arterial occlusions (59). Furthermore, it has been shown that NETs alone are sufficient for vascular occlusions under septic conditions in the absence of host enzymes DNase1 and DNase1L3 (60) cleaves histones and interferes with their cytotoxic activity in a purified system, it had no effect on NETs-induced cytotoxicity suggesting that histone-dependent cytotoxicity is protected from APC degradation (63,64).…”