The evolving biology of microglia in Alzheimer's disease.

Alzheimer's disease (AD) is typified by a robust microglial-mediated inflammatory response within the brain. Indeed, microglial accumulation around plaques in AD is one of the classical hallmarks of the disease pathology. Although microglia have the capacity to remove β-amyloid deposits and alleviate disease pathology, they fail to do so. Instead, they become chronically activated and promote inflammation-mediated impairment of cognition and cytotoxicity. However, if microglial function could be altered to engage their phagocytic response, promote their tissue maintenance functions, and prevent release of factors that promote tissue damage, this could provide therapeutic benefit. This review is focused on the current knowledge of microglial homeostatic mechanisms in AD, and mechanisms involved in the regulation of microglial phenotype in this context.