The International Journal of Biochemistry & Cell Biology
Cells in focusMicroglia: Proliferation and activation driven by the P2X7 receptor
Section snippets
Cell origin and plasticity
The central nervous system (CNS) is composed of two major types of cells, neurons and glia. The name ‘glia’ is attributed to astrocytes and oligodendrocytes (both being of neuroectodermal origin), and microglia (‘brain macrophages’) of a monocytic lineage. Microglia are the immunoeffector cells of the CNS, participating in innate immune responses and communicating with other immunological cells via cytokines, chemokines and other bio-active substances. Microglia comprise approximately 10% of
Functions
The functions of microglia are not fully understood, but do include the following: (1) sensing and reacting to CNS injury, (2) removing cellular debris from the brain by phagocytosis, (3) regulating astrogliosis, (4) orchestrating neuroimmune function in CNS, and (5) assisting in the development of CNS (e.g., by secreting growth factors and removing apoptotic cells). Microglial functions can be modulatory, protective or deleterious to the functions of surrounding cells, including astrocytes and
Associated pathologies
Neuroinflammation signifies the brain's patterned response to insult with a number of immunomodulatory responses such as release of cytokines and chemokines set in motion with the activation of glia. Microglial-mediated neuroinflammation is associated with conditions such as AD, HIV-dementia, Parkinson's disease, prion disease, amyotrophic lateral sclerosis, and multiple sclerosis (Garden, 2002, Hall et al., 1998, McGeer et al., 1988, Tan et al., 1999). Chronic activation of microglia exposes
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