For instance, it has been shown that suppression of Jmjd3, which is essential for M2 microglia polarization, in the substantia nigra (SN) in vivo dramatically causes microglial overactivation and exacerbated dopamine (DA) neuron death in a PD animal model [35], indicating a protective role of M2 microglia in this process. This evidence concerns the gene KDM6B and Parkinson disease.