Abstract 15277: Caspase Inhibition Reduces Aortic Valve Stenosis in Apolipoprotein E Deficient Mice
Background: Aortic valve stenosis (AS) is the second most common indication for adult heart surgery in western countries. However, molecular mechanisms that lead to leaflet thickening and calcification are not well understood. Several studies describe the presence of apoptotic cells in human and experimental AS. To understand the role of apoptosis in the pathogenesis of AS, we tested the effect of the pan-caspase inhibitor quinoline-Val-Asp-difluorophenoxymethyl-ketone (Q-VD-OPh) in Apo-E −/− mice on long-term western diet.
Methods and Results: After 7 months of western diet, Apo-E −/− mice were randomly assigned into 2 groups receiving either 21 days of continued caspase-inhibitor treatment Q-VD-OPH or control peptide. Porcine aortic valve myofibroblasts (PAVMF) were cultured with oxidized-LDL (50 μg/ml) for 7 days. Effects of Q-VD-OPH or control peptide pre-incubation on alkaline phosphatase (AP) activity was assessed and compared to controls. Controls showed markedly thickening of the aortic valve leaflets that was significantly reduced by caspase inhibition (0.23±0.11mm vs. 0.12±0.07mm, p<0.01). Frequent apoptosis of endothelial cells and interstitial cells was detectable by immunostaining for active-caspase-3 that was virtually absent after treatment with Q-VD-OPH. Von Kossa staining showed significant calcification of aortic valve leaflets of mice treated with control peptide, which was not present in mice treated with the caspase inhibitor (4.1±3.2 % vs. 1.0±0.6 % of total leaflet area). Pre-incubation of PAVMF with Q-VD-OPH completely prevented ox-LDL-induced changes in AP activity (2119±231 vs. 1415±328 RFU; p<0.05). No differences between ox-LDL±control peptide were observed.
Conclusion: Experimental AS in Apo-E −/− mice on long-term western diet is associated with frequent apoptosis of endothelial and interstitial cells. Caspase-inhibitor treatment resulted in decreased aortic valve leaflet thickness and calcification in vivo and in reduced AP activity in vitro. These results indicate that apoptosis may be a key step in the pathogenesis of calcific aortic stenosis and that inhibiting this process may serve as a novel approach in the management of aortic valve disease.
- © 2010 by American Heart Association, Inc.