How microbiota shape microglial phenotypes and epigenetics.
Erny D, Prinz M
Among the myeloid cells in the central nervous system (CNS) microglia are the main representatives of the innate immune system. Microglial fulfil tasks beyond phagocytosing debris and host defense against invading microorganism. During brain development microglia guide for example neurons for proper CNS formation, in adulthood they maintain tissue homeostasis and in aging microglia may become pro-inflammatory and finally exhausted. Recently, several endogenous and exogenous factors were identified that essentially shape the microglial phenotype during both steady-state and pathological conditions. This review summarizes key extrinsic and intrinsic factors, with special focus on the host microbiota, that essentially influence microglia functions and states during development, homeostasis, and disease.