**2. Astrocytes in inflammation**

Despite that microglia are the main immune cells of the central nervous system (reviewed in Ransohoff, 2010), astrocytes can also become reactive and contribute to neuroinflammation and are the focus of this chapter, with microglial inflammatory effects residing beyond the scope of this chapter. During neuroinjury or neurodegeneration the production of cytokines induce astrogliosis in which astrocytes increase glial fibrillary acidic protein (GFAP) and vimentin expression as well as an array of other genes. This response increases neuronal survival and includes both supportive factors (e.g. growth factors and glutamate transporters) and cytokines to sustain/promote neuroinflammation. Interestingly, during neuroinflammation the number of astrocytes increases by the differentiation of chondroitin sulfate proteoglycan, NG2, positive cells to astrocytes and not by astrocytic proliferation (Gowing et al., 2008).
