Sonodynamic effect of an anti-inflammatory agent--emodin on macrophages

Emodin has been used as an anti-inflammatory agent and inflammation is a crucial feature of atherosclerosis. Here, we investigated the sonodynamic effect of emodin on macrophages, the pivotal inflammatory cells in atherosclerotic plaque. THP-1 derived macrophages were cultured with emodin and exposed to ultrasound. Six hours later, unlike the cells treated for 5 and 10 min, the viability of cells treated for 15 min decreased significantly and the cells showed typical apoptotic chromatin fragmentation. The percentage of apoptotic and necrotic cells in the sonodynamic therapy (SDT) group was higher than that in the ultrasound group. Two hours after treatment for 15 min, the cytoskeleton lost its original features as the filaments dispersed and the cytoskeletal proteins aggregated. The percentage of cells with disturbed cytoskeletal filaments in the SDT group was higher than that in the ultrasound group. These results suggest emodin has a sonodynamic effect on macrophages and might be used as a novel sonosensitizer for SDT for atherosclerosis.