Caspase-1 mediates hyperlipidemia-weakened progenitor cell vessel repair

Caspase-1 activation senses metabolic dangerassociated molecular patterns (DAMPs) and mediates the initiation of inflammation in endothelial cells. Here, we examined whether the caspase-1 pathway is responsible for sensing hyperlipidemia as a DAMP in bone marrow (BM)-derived Stem cell antigen-1 positive (Sca-1⁺) stem/progenitor cells and weakening their angiogenic ability. Using biochemical methods, gene knockout, cell therapy and myocardial infarction (MI) models, we had the following findings: 1) Hyperlipidemia induces caspase-1 activity in mouse Sca-1⁺ progenitor cells in vivo; 2) Caspase-1 contributes to hyperlipidemiainduced modulation of vascular cell death-related gene expression in vivo; 3) Injection of Sca-1⁺ progenitor cells from caspase-1^-/- mice improves endothelial capillary density in heart and decreases cardiomyocyte death in a mouse model of MI; and 4) Caspase-1^-/- Sca-1⁺ progenitor cell therapy improves mouse cardiac function after MI. Our results provide insight on how hyperlipidemia activates caspase-1 in Sca-1⁺ progenitor cells, which subsequently weakens Sca-1⁺ progenitor cell repair of vasculature injury. These results demonstrate the therapeutic potential of caspase-1 inhibition in improving progenitor cell therapy for MI.