ABSTRACT
This study is to investigate the effects of indirubin on ATP-induced immune responses of macrophages. For this, neutral red dye uptake method was used to test phagocytosis, MTT assay was used for measuring cell death, and reactive oxygen species (ROS) was tested with fluorescent probe DHE. The data showed that extracellular ATP attenuated phagocytosis, induced cell death and increased ROS production, and these effects were restored by pre-treating with indirubin. This result suggested that indirubin blockade the effects of ATP on macrophages, because extracellular ATP-induced effects are dependent on P2 receptors, in particular P2X7 receptors. Furthermore, the effects of indirubin on the activation of P2 receptors were tested, in particular P2X7 receptors. The data showed that indirubin significantly decreased ATP-induced, P2 receptors mediated intracellular Ca2+ concentration ([Ca2+]i) rise and inhibited P2X7 receptor-based ethidium bromide (EB) dye uptake. These results suggested the inhibitory effects of indirubin on the activation of P2X7 receptors, which may underlying the effects on ATP induced ROS production, phagocytosis attenuation and cell death of macrophages.