Glia in neuroimmunology

Abstract

Accumulation of glia, especially microglia and astrocytes, is commonly observed in a variety of neurological disorders and has long been considered as static scar formation, called “gliosis." However, recent studies have revealed that these accumulated glial cells are activated and produce various factors, either toxic or protective to neural tissue. Gliosis is no more static scar, but inflammation actively participates in the development of disease processes and is called “neuroinflammation." The brain has long been considered as an immunologically privileged site. Innate immunity by microglia had been believed to be the only defense mechanism in the brain. However, in autoimmune diseases in the central nervous system, such as multiple sclerosis, glial cells are capable to function as antigen-presenting cells, effector cells to damage neural tissue, and even a negative regulator against inflammation. Activated glial cells are also involved in pathophysiology of neurodegenerative and psychiatric disorders. Thus, understanding of glial neuroinflammation is important to elucidate pathophysiology of various neuropsychological disorders and may give us clues for future therapeutic strategies against these diseases.