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Investigating Aortic Valve Calcification via Isolation and Culture of T Lymphocytes using Feeder Cells from Irradiated Buffy Coat
Published on: February 4, 2021
Histological evaluation of autophagic cell death in calcified aortic valve stenosis
Pamela Somers1, Michiel Knaapen, Mark Kockx
1Department of Pathology, Middelheim Hospital Antwerp, Antwerp, Belgium.
Insights
Autophagy, not apoptosis, is the primary cell death mechanism in calcified aortic valves. This finding suggests autophagy contributes to matrix vesicle release, inflammation, and eventual aortic valve mineralization.
Area of Science:
- Cardiovascular Pathology
- Cell Biology
- Biochemistry
Background:
- Aortic valve calcification is a prevalent valvular lesion in Western populations.
- Cellular degeneration in valvular cusps accompanies calcification, but the precise cell death mechanisms remain unclear.
- Understanding cell death pathways is crucial for elucidating the pathogenesis of aortic valve disease.
Purpose of the Study:
- To investigate the predominant cell death mechanism in human aortic valve calcification.
- To differentiate between apoptosis and autophagy as contributors to valvular degeneration.
- To explore the role of cell death in the progression of aortic valve mineralization.
Main Methods:
- Comparative analysis of 12 surgically resected calcified aortic valves and 12 autopsy-obtained control valves.
- Histological examination using Hematoxylin and eosin and Alcian blue staining.
- Immunohistochemical detection of neurons (PGP9.5, neurofilament), autophagy (ubiquitin), and apoptosis (TUNEL assay).
- Co-localization studies of Alizarin red with ubiquitin labeling.
Main Results:
- Significant mineralization observed in 10/12 surgical valves versus 1/12 autopsy valves.
- Ubiquitin labeling (autophagy marker) was significantly higher in calcified valves (9/12) compared to controls (1/12).
- TUNEL-positive labeling (apoptosis marker) was rare, primarily on the endothelial layer.
Conclusions:
- Autophagy, indicated by ubiquitin accumulation, is the principal mechanism of cell death in calcified aortic valves.
- Apoptosis plays a minimal role in the degenerative process of aortic valve calcification.
- Autophagic cell death may initiate matrix vesicle release, attracting inflammatory cells and driving mineralization in degenerative aortic valves.
Background And Aim Of The Study:
Calcification in aortic valves is the most common valvular lesion in western populations. This event is correlated with cellular degeneration in the valvular cusps, although there is no exact evidence how these cells die: this requires further exploration.
Methods:
Twelve human severely calcified aortic valves obtained during cardiac surgery were studied by semi-quantitative analysis, and results compared with data from 12 human control aortic valves obtained during autopsy. Tissue analysis was by hematoxylin and eosin and Alcian blue staining. Detection of neurons was by immunohistochemical staining of PGP9.5 and neurofilament. In order to detect autophagy, an immunohistochemical staining for ubiquitin was used. The TUNEL technique was used to detect apoptosis. Co-localization of Alizarin red with ubiquitin labeling was performed on non-decalcified aortic valves.
Results:
Hematoxylin and eosin staining showed moderate to severe mineralization in 10 of 12 patients in the surgical group, but in only one of 12 in the autopsy group. No significant observations were made with regard to PGP9.5 and neurofilament staining. Moderate to severe ubiquitin labeling was found initially in the majority of the surgical resection group (9/12) compared to a minority in the autopsy group (1/12). TUNEL-positive labeling was very rare and found mostly at the endothelial layer of the valvular cusps.
Conclusion:
Immunohistochemical methods showed the main cell death mechanism involved in the calcification of aortic leaflets to be autophagy rather than apoptosis. These findings suggest that autophagic cell death might play a role in the release of matrix vesicles in early degenerative aortic valves, thereby attracting inflammatory cells, and this could eventually lead to mineralization.
