Abstract: FR-PO391
The Effects of Neutrophil Extracellular Traps (NETs) on Endothelial Health and Function
Session Information
- Hypertension and CVD: Basic
November 03, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Hypertension and CVD
- 1601 Hypertension and CVD: Basic
Authors
- Landry, Chloé, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
- Burger, Dylan, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
Background
Neutrophil extracellular traps (NETs) are intricate webs of extracellular DNA, citrullinated histones and granular protein that play an essential role in innate immunity. Dysregulation of NET formation has been implicated in acute kidney injury, lupus nephritis, and diabetic kidney disease. However, the mechanisms by which NETs contribute to kidney injury have yet to be fully elucidated. As the vasculature may represent a common pathogenic target, we examined the effect of NETs on endothelial cells in vitro and on ex vivo mesenteric artery function.
Methods
The human promyelocytic cell line, HL-60, was used to generate neutrophil-like cells in vitro. Differentiation was induced by incubation with 1.25% dimethyl sulfoxide (DMSO) for 5 days. Differentiated cells were then stimulated with 500 nM phorbol 12-myristate 13-acetate (PMA) for 4 hours to induce NET formation. NETs were isolated from the cell culture medium by differential centrifugation. Cultured Human Umbilical Vein Endothelial Cells (HUVECs) were treated with the isolated NETs at 0.5-500 ng/ml for 24 hours. Cell viability and proliferative capacity were measured in the treated HUVECs using an XTT and BrdU assay, respectively. Second-order mouse mesenteric arteries were harvested and mounted to a wire myograph. Vessels were treated with the isolated NETs at 15 ng/mL for 30 minutes, after which we measured vascular relaxation during chemical stimulation with acetylcholine, to assess their effect on endothelium-dependent vasorelaxation.
Results
NETs decreased HUVEC viability ~2-fold at 5 ng/ml (P=<0.0001) and dose dependently decreased proliferative capacity from 0.5-500 ng/ml, with proliferation being decreased by ~80% at 500 ng/ml. NETs also significantly impaired endothelium-dependent vasorelaxation, with relaxation being 43% lower in treated vessels at 10-6 M acetylcholine. This was reflected in smaller pD2 values in NET-treated vessels (5.55 vs 6.72 in control vessels) (p=0.0284).
Conclusion
These results show that NETs induce endothelial cell injury in vitro and impair endothelial function in intact vessels. Identifying the underlying mechanisms of NET-induced endothelial injury may help further understand their contribution to kidney and cardiovascular injury.