<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Infective endocarditis is a disease that affects the endocardium and often alters heart valves, notably the aortic valve. Bacteraemia and valvular endothelial damage play an essential role in the pathogenesis of infective endocarditis. The pertinent literature suggests that neutrophil extracellular traps are important contributors to the development of the disease. However, features of the valvular damage and contribution of neutrophils to the alteration of cardiac tissue are not explored sufficiently. The purpose of this study was to investigate the occurrence and distribution of neutrophilic leukocytes and neutrophil extracellular traps in native aortic valves affected by infective endocarditis, using histopathology and immunohistochemistry assays. In addition, the presence of vegetations on the heart valve was determined. Infiltration of neutrophils into the valvular leaflet was significantly more severe at the free margin (mean 5.89 ± 3.00, <italic>p</italic> &lt; 0.001) and the middle portion (mean 4.58 ± 3.64, p = 0.032) when compared to the base portion (2.05 ± 1.90). No significant differences in neutrophilic leukocyte infiltrating inflammatory lesions were found between cusp layers. The presence of myeloperoxidase and citrullinated histone expression characteristic of neutrophil extracellular traps was demonstrated by the use of immunohistochemistry in IE-affected valvular leaflets and vegetations. Collectively, the study results suggest that the free cusp margin and its middle portion of the aortic valve are exposed to enforced blood flow; endothelial damage and vegetation formation are likely to occur along with the presence of infective endocarditis-related bacteraemia.</p>
</abstract>

Infective endocarditis is a disease that affects the endocardium and often alters heart valves, notably the aortic valve. Bacteraemia and valvular endothelial damage play an essential role in the pathogenesis of infective endocarditis. The pertinent literature suggests that neutrophil extracellular traps are important contributors to the development of the disease. However, features of the valvular damage and contribution of neutrophils to the alteration of cardiac tissue are not explored sufficiently. The purpose of this study was to investigate the occurrence and distribution of neutrophilic leukocytes and neutrophil extracellular traps in native aortic valves affected by infective endocarditis, using histopathology and immunohistochemistry assays. In addition, the presence of vegetations on the heart valve was determined. Infiltration of neutrophils into the valvular leaflet was significantly more severe at the free margin (mean 5.89 ± 3.00, p < 0.001) and the middle portion (mean 4.58 ± 3.64, p = 0.032) when compared to the base portion (2.05 ± 1.90). No significant differences in neutrophilic leukocyte infiltrating inflammatory lesions were found between cusp layers. The presence of myeloperoxidase and citrullinated histone expression characteristic of neutrophil extracellular traps was demonstrated by the use of immunohistochemistry in IE-affected valvular leaflets and vegetations. Collectively, the study results suggest that the free cusp margin and its middle portion of the aortic valve are exposed to enforced blood flow; endothelial damage and vegetation formation are likely to occur along with the presence of infective endocarditis-related bacteraemia.

Neutrophilic Leukocytes and Neutrophil Extracellular Traps in Native Aortic Valve Endocarditis

Centre of Cardiac Surgery, Pauls Stradiņš Clinical University Hospital

Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences.

This work is licensed under the Creative Commons Attribution 4.0 International License.

Infective endocarditis is a disease that affects the endocardium and often alters heart valves, notably the aortic valve. Bacteraemia and valvular endothelial...

Neutrophilic Leukocytes and Neutrophil Extracellular Traps in Native Aortic Valve Endocarditis

Published Online: Mar 09, 2023

Page range: 41 - 48

Received: Mar 28, 2022

Accepted: Aug 02, 2022

DOI: https://doi.org/10.2478/prolas-2023-0005

Keywords
infective endocarditis, NET, vegetation, immunohistochemistry

© 2023 Niks Ričards Goldiņš et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Neutrophilic Leukocytes and Neutrophil Extracellular Traps in Native Aortic Valve Endocarditis

Published Online: Mar 09, 2023

Page range: 41 - 48

Received: Mar 28, 2022

Accepted: Aug 02, 2022

DOI: https://doi.org/10.2478/prolas-2023-0005

Keywordsinfective endocarditis, NET, vegetation, immunohistochemistry

© 2023 Niks Ričards Goldiņš et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Keywords
infective endocarditis, NET, vegetation, immunohistochemistry