Interleukin-6 expression and regulation in astrocytes

The physiological function of interleukin-6 (IL-6) within the central nervo us system. (CNS) is complex; IL-6 exerts neurotrophic and neuroprotective e ffects, and yet can also function as a mediator of inflammation, demyelinat ion, and astrogliosis, depending on the cellular context. In the normal bra in, IL-6 levels remain low. However, elevated expression occurs ia injury, infection, stroke, and inflammation. Given the diverse biological functions of IL-6 and its expression in numerous CNS conditions, it is critical to u nderstand its regulation in the brain in order to control its expression an d ultimately its effects. Accumulating data demonstrate that the predominan t CNS source of IL-6 is the activated astrocyte. Furthermore, a wide range of factors have been demonstrated to be involved in IL-6 regulation by astr ocytes. In this review, we summarize information concerning IL-6 regulation int astrocytes, focusing on the role pf proinflammatory factors, neurotran smitters, and second messengers. (C) 1999 Elsevier Science B.V. All rights reserved.