Introduction: Aortic valve stenosis (AVS) is the most common valvular disease in humans. The development of aortic valve stenosis is characterized by inflammation and calcification, both are regulated by ceramides. Ceramide Synthase 5 (CerS5) is a key enzyme in the synthesis of the highly abundant d18:1,16:0 ceramide (C16), which is associated with increased cardiovascular mortality and obesity. In this study, we investigated the impact of loss of CerS5 in combination with high fat / high cholesterol diet on the development of AVS in a murine model.  

Methods and Results: For AVS development we used a wire-injury, where the aortic valve is injured with a wire under echocardiographic control. In two experiments CerS5-/- mice and wild type controls were fed with high fat / high cholesterol diet or normal chow. In groups with high fat / high cholesterol diet peak velocity was significantly lower in CerS5-/- mice compared to wild type. Furthermore, in the valves of in CerS5-/- mice, we found less immune cell infiltration into the aortic valve, measured with CD68 staining, and less calcification, measured with von Kossa staining (A). In the groups with normal chow these effects were not visible (B). In vitro experiments with human aortic valvular interstitial cells (VICs) revealed an upregulation of CerS5 and CerS6 after treatment with pro calcifying medium (PCM) and after treatment with RNAi against CerS5 in vitro calcification was reduced in these cells (C). 

Conclusion: We were able to show that loss of CerS5 function in combination with high fat / high cholesterol diet can reduce AVS development in vivo with a decreased immune cell infiltration into the aortic valve. In addition, we found the anti-inflammatory effects of CerS5 knockout to be dependent on high fat / high cholesterol diet. In vitro experiments revealed that CerS5 is involved in valvular interstitial cell calcification. In summary CerS5 could serve as a target for a pharmacological treatment of AVS and merits further investigation.