[Cellular and molecular heterogeneity of CNS macrophages in health and disease]

The central nervous system (CNS) is a highly complex collection of various cell-types, such as neurons, glial cells, vascular cells, and immune cells, and their complex and dynamic interactions enable to achieve highly sophisticated functions of the CNS. Among such CNS cells are microglia, which are well-known primary CNS macrophages localized in the CNS parenchyma and play a pivotal role in the maintenance of tissue homeostasis. Besides microglia, there are anatomically distinct macrophage populations at the border of the CNS, such as meninge, and perivascular space, called CNS-associated macrophages (CAMs). Recent studies have given novel insights into the nature of CAMs. In this review, I will discuss our current knowledge of the origins, the cellular properties of CNS macrophages.