IL4 and epilepsy: Inspiringly, intraperitoneal injection of IL-4 can regulate the phenotype of microglia after epilepsy, which might be explained by two potential mechanisms: one is the permeability of the blood-brain barrier changes after epilepsy, allowing IL-4 to enter the brain and play a role; the other one is that IL-4 regulates the peripheral mononuclear system and thus affects the microglia in the brain (Ravizza et al., 2008; Villa et al., 2016).