Background/Objectives: Recent studies suggest that plasma ceramide levels may be better predictors of CVD risk than LDL cholesterol. Ceramides are part of the sphingolipid class of lipids and are the central intermediates in complex sphingolipid biosynthesis. Sphingolipids are crucial for cellular structure and have important biological roles as complex signaling lipids, structurally and functionally differentiated by their acylated fatty acid. Higher plasma concentrations of 16:0 ceramide are associated with increased risk of heart failure. In contrast, higher concentrations of 22:0 plus 24:0 ceramide are associated with lower risk. We aim to address how alterations in these lipids can affect the human cardiac hypertrophic response. Methods: We silenced the ceramide synthase genes (CERS) responsible for the production of 16:0 ceramide (CERS5/6) or 22:0 and 24:0 ceramide (CERS2) in immortalized human ventricular cardiomyocytes and examined the altered cardiac hypertrophic response to phorbol 12-myristate 13-acetate treatment by examining changes in the transcriptome. Results: We discovered that silencing CERS2 or CERS5/6 drastically altered the cardiac cell hypertrophic response. We demonstrated that human cardiomyocytes with silenced CERS2 appeared to have an exacerbated hypertrophy response, while cardiomyocytes with silenced CERS5/6 had a more favorable response, suggesting that CERS2 and CERS5/CERS6 and their gene product metabolites may have opposing roles in the development and progression of CVD. Conclusions: The exact mechanisms through which various ceramides contribute to CVD progression are still unknown. This study will help elucidate the role of specific ceramides during cardiac hypertrophy and suggests that drugs targeting specific sphingolipids can potentially be a viable treatment option for the prevention of CVD.

Background/Objectives: Sphingolipids are a class of lipids that play important structural and functional roles in the cell. Specific ceramide species are distinguishable through the fatty acid that is acylated to the sphingosine backbone, leading to distinct biological activities. Generally, long-chain (LC) ceramides (16:0 and 18:0) drive metabolic dysfunction resulting in the progression of different disease states, while very long-chain (VLC) ceramides (22:0 and 24:0) are thought to be either beneficial against disease progression or benign. In this study, we sought to alter the cellular composition of LC and VLC ceramides in ventricular HCMs to investigate how alterations in these lipids can affect the transcriptome of otherwise healthy HCMs. Methods: Here, we used specific siRNA to knockdown the ceramide synthases responsible for the production of LC and VLC ceramides in ventricular HCMs and investigated the changes in the transcriptome of HCMs with CERS2 or CERS5/6 silenced compared to control conditions. Results: Knocking down CERS2 led to an increase in cell death as well as widespread reductions in cellular VLC sphingolipids. Additionally, we demonstrated that VLC sphingolipid species may play a protective role in maintaining cardiovascular function and that reducing these lipids may contribute to cardiac dysfunction. Similarly, knocking down CERS5 and CERS6 led to reduced LC ceramides and also resulted in profound changes in gene transcription. Interestingly, multiple genes and pathways were affected in the opposite direction when compared to the changes observed with the CERS2 knockdown. Conclusions: Taken together, our results suggest pathways through which VLC ceramides may contribute to cardiac protection, and pathways where LC ceramides may promote HCM stress and the development of cardiac disease.