Astrocyte loss and astrogliosis in neuroinflammatory disorders.

Neuroinflammation can lead to either damage of astrocytes or astrogliosis. Astrocyte loss may be caused by cytotoxic T cells as seen in Rasmussen encephalitis, auto-antibodies such as in neuromyelitis optica (aquaporin-4 antibodies), or cytokines such as TNF-α in major depressive disorder. Interleukins-1 and -6 appear to be important molecular mediators of astrogliosis. Chronic focal lesions in multiple sclerosis are characterized by a very dense astrogliosis. Other mechanisms, such as astrocytic β2 adrenergic receptor deficiency, upregulation of endothelin-1 and tissue transglutaminase, may contribute to astroglial scarring in multiple sclerosis.