Multiple roles for astrocytes as effectors of cytokines and inflammatory mediators.

Astrocytes are increasingly recognized as exerting complex functions essential for normal neural activity in the healthy central nervous system (CNS). Because astrocytes also respond to all forms of CNS injury or disease, there is growing interest in how reactive astrogliosis might alter astrocyte functions and thereby affect neural functions. Reactive astrogliosis is heterogeneous and regulated in a context specific manner by different molecular signals. Prominent among astrocyte signaling mechanisms is the ability to respond to, as well as to produce, many different cytokines and inflammatory mediators. These signaling mechanisms enable astrocytes to interact with diverse cell types in ways that may contribute to crosstalk between immune/inflammatory and neural systems. Consistent with this notion is the increasing evidence that cytokines and inflammatory mediators modulate astrocyte signaling not only to influence immune and inflammatory activities in the CNS, but also to influence synaptic and neural functions in ways that may affect complex behaviors such as sickness behavior, pain, appetite, sleep, and mood.