Neutrophil Extracellular Traps Induce Endothelial Cell Activation and Tissue Factor Production Through Interleukin-1α and Cathepsin G

Abstract

Objective- Coronary artery thrombosis can occur in the absence of plaque rupture because of superficial erosion. Erosion-prone atheromata associate with more neutrophil extracellular traps (NETs) than lesions with stable or rupture-prone characteristics. The effects of NETs on endothelial cell (EC) inflammatory and thrombogenic properties remain unknown. We hypothesized that NETs alter EC functions related to erosion-associated thrombosis. Approach and Results- Exposure of human ECs to NETs increased VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1) mRNA and protein expression in a time- and concentration-dependent manner. THP-1 monocytoid cells and primary human monocytes bound more avidly to NET-treated human umbilical vein ECs than to unstimulated cells under flow. Treatment of human ECs with NETs augmented the expression of TF (tissue factor) mRNA, increased EC TF activity, and hastened clotting of recalcified plasma. Anti-TF-neutralizing antibody blocked NET-induced acceleration of clotting by ECs. NETs alone did not exhibit TF activity or acceleration of clotting in cell-free assays. Pretreatment of NETs with anti-interleukin (IL)-1α-neutralizing antibody or IL-1Ra (IL-1 receptor antagonist)-but not with anti-IL-1β-neutralizing antibody or control IgG-blocked NET-induced VCAM-1, ICAM-1, and TF expression. Inhibition of cathepsin G, a serine protease abundant in NETs, also limited the effect of NETs on EC activation. Cathepsin G potentiated the effect of IL-1α on ECs by cleaving the pro-IL-1α precursor and releasing the more potent mature IL-1α form. Conclusions- NETs promote EC activation and increased thrombogenicity through concerted action of IL-1α and cathepsin G. Thus, NETs may amplify and propagate EC dysfunction related to thrombosis because of superficial erosion.

Neutrophil extracellular traps in nasal secretions of patients with stable and exacerbated chronic rhinosinusitis and their contribution to induce chemokine secretion and strengthen the epithelial barrier

“…Another study demonstrated that NETs could promote further leucocyte recruitment to lesion sites and thus potentiate the regional inflammatory response. 45 In agreement with these previous studies, our data showed that neutrophils migration increases in endothelial cells treated with NETs or H3Cit. Endothelial cells treated with NETs or H3Cit showed up-regulation of ICAM-1 levels, supporting the notion that NETs induce neutrophil migration.…”

“…nonasal epithelium, is a common feature of any form of CRS [42][43][44]. More comparable studies are required on these subjects.Another study demonstrated that NETs could promote further leucocyte recruitment to lesion sites and thus potentiate the regional inflammatory response 45. By contrast to the aforementioned studies,[42][43][44] our data showed that NETs andH3Cit, a key component of NETs, strengthen the epithelial barrier even at the basal level, and also reverse cytokine-induced increases in sinonasal epithelial permeability.…”

“…This is in line with a recent study showing that human saphenous vein and umbilical vein endothelial cells treated with NETs exhibit higher concentration of ICAM-1. 45 Therefore, NETs can mediate inflammatory responses by increasing the neutrophil migration through the increase of the endothelial cells surface expression of ICAM-1 in CRS.…”

Atherosclerosis: Beyond the lipid storage hypothesis. The role of autoimmunity

“…Recent studies, however, have provided substantial evidence of their participation in the pathogenesis of atherosclerosis and atherosclerosis-related CV events. 41,42 Additionally, the presence of NETs in human atherosclerotic vessel biopsies was observed in proximity and correlated with apoptotic endothelial cells 43 While the role of neutrophils in thrombosis was known, more recently become evident that TF is also present on NETs released by neutrophils isolated from blood drawn near occluded arteries in the cases of acute coronary syndromes, indicating their procoagulant properties. The invading bacteria get trapped in NETs and as a result, are killed or their virulence factors get degraded.…”

“…41 NETs can promote endothelial activation or damage since vascular cell adhesion molecule-1 (VCAM-1), intracellular adhesion molecule-1 (ICAM-1) and tissue factor (TF) mRNA and protein expression in endothelial cells were induced upon contact with NETs. 41,42 Additionally, the presence of NETs in human atherosclerotic vessel biopsies was observed in proximity and correlated with apoptotic endothelial cells 43 While the role of neutrophils in thrombosis was known, more recently become evident that TF is also present on NETs released by neutrophils isolated from blood drawn near occluded arteries in the cases of acute coronary syndromes, indicating their procoagulant properties. 44 Furthermore, NETs affects cytokine production.…”