HDAC2 and Alzheimer disease: This is exemplified by the notable findings that the genetic deletion of microglial Hdac1 and Hdac2 substantially ameliorated the cognitive deficits of 5xFAD mice by enhancing microglial phagocytosis of Aβ.298 Despite numerous studies supporting the pivotal roles of SCFAs in mediating gut microbiota-microglia communication, mechanistic studies elucidating the underlying mechanisms of SCFAs in AD remain limited and yield conflicting results.