Abstract
Objective: Neutrophil infiltration plays an important role in the initiation and development of abdominal aortic aneurysm (AAA). Recent studies suggested that neutrophils could release neutrophil extracellular traps (NETs), leading to tissue injury in cardiovascular diseases. However, the role of NETs in AAA is elusive. This study aimed to investigate the role and underlying mechanism of NETs in AAA development.Methods and Results: An angiotensin II (Ang II) infusion-induced AAA model was established to investigate the role of NETs during AAA development. Immunofluorescence staining showed that citrullinated histone 3 (citH3), myeloperoxidase (MPO), and neutrophil elastase (NE) (NET marker) expressions were significantly increased in Ang II-infused ApoE−/− mice. The circulating double-stranded DNA (dsDNA) level was also elevated, indicating the increased NET formation during AAA. PAD4 inhibitor YW3-56 inhibited Ang II-induced NET formation. Disruption of NET formation by YW3-56 markedly reduced Ang II-induced AAA rupture, as revealed by decreased aortic diameter, vascular smooth muscle cell (VSMC) apoptosis, and elastin degradation. Apoptosis of VSMC was evaluated by TUNEL staining and Annexin V-FITC/PI staining through flow cytometry. Western blot and inhibition experiments revealed that NETs induced VSMC apoptosis via p38/JNK pathway, indicating that PAD4-dependent NET formation played an important role in AAA.Conclusions: This study suggests that PAD4-dependent NET formation is critical for AAA rupture, which provides a novel potential therapeutic strategy for AAA disease.
Highlights
Abdominal aortic aneurysm (AAA) is clinically defined as the increase of aortic diameter by at least 50% compared with the regular diameter
Immunofluorescence staining showed that citrullinated histone 3, myeloperoxidase (MPO), and neutrophil elastase (NE) (NET marker) expressions were significantly increased in Ang Angiotensin II (II)-infused Apolipoprotein E (ApoE)−/− mice
Apoptosis of Vascular smooth muscle cells (VSMCs) was evaluated by TdT-mediated dUTP nick end labeling (TUNEL) staining and Annexin V-FITC/PI staining through flow cytometry
Summary
Abdominal aortic aneurysm (AAA) is clinically defined as the increase of aortic diameter by at least 50% compared with the regular diameter. AAA is common in men aged over 65 years [1]. AAA rupture leads to a 30-day mortality rate up to 70% [2]. Surgical treatment is the most important strategy for treating AAA [3]. The risk of surgery is high and long-term survival is still dissatisfactory [4, 5]. Looking for more effective treatments for AAA requires a better understanding of its pathological process
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