Microglia and macrophages in central nervous systems

Parenchymal microglia and nonparenchymal macrophages in the central nervous system (CNS) are mononuclear phagocytes, which belong to the hematopoietic system and are involved during development, homeostasis, and diseased states (inflammation, immune responses, etc.) of CNS. With the recent rapid development of medical science and technology, the secretive roles of these cells in the developmental origin, homeostasis, and diseases are being identified. Some of them are scientifically recognized, but some are still in dispute. The activation of microglia and macrophages is commonly involved in the neuroinflammatory response in pathological CNS. Thus, here, we discuss their normal roles in the development and (un)healthy status of the inflammatory and immune response in the various neuropathological CNSs. Finally, this review will contribute to understanding the connection between CNS and the immune system in order to control neurological diseases via neuroimmune modulation.