Roles in immune responses

Microglia are best known as the mononuclear phagocytes of the central nervous system (CNS) parenchyma. As a resident glial cell population, microglia play key roles during the initiation, propagation, and/or resolution of inflammation. Recently, the discovery that microglial cells continuously survey their local CNS environment in vivo improved our understanding of their immune-surveillance properties in health and disease. Microglial interactions with other elements of the immune system and resident cells of the CNS define a fine balance between neuroprotection and irreparable tissue damage. In this chapter we highlight the innate immune properties of microglia, with a focus on events that initiate an inflammatory response within the brain proper including, Toll-like receptors, inflammasomes, cytokines, and chemokines, and their relationship to immune-mediated disease exacerbation or resolution.