PPARG and neurodegenerative disease: What’s more, some mechanisms of microglia polarization modulation are the same in vitro and in vivo of individuals with neurodegenerative diseases, such as PPAR-γ agonist (Pisanu et al., 2014; Yang et al., 2019), IL-4 and so on, while other mechanisms verified in vitro are not applicable in neurodegenerative diseases, which needs further research.