Cytokine network in the central nervous system and its roles in growth and differentiation of glial and neuronal cells

Cells resident within the central nervous system (CNS) can synthesize, secrete and respond to inflammatory cytokines not only contributing to the responses to injury or immunological challenge within the CNS, but also regulating their own growth and differentiation potential. The actions and cell communication via cytokines in the CNS are designated as the CNS cytokine network, in which microglia and astrocytes play the central roles. To further characterize the CNS cytokine network we investigated the differences in roles of these cells, and found that microglia might contribute to the early phase of cytokine production reaction and that astrocytes might contribute the late phase of the reaction. We also investigated roles of inhibitory cytokines such as TGF β, IL-4, and IL-10, and showed that each might play a distinct role in the inhibitory regulation in the CNS. We summarized our previous report about cellular distribution of cytokine receptors in the CNS cells and discussed their roles in the CNS cytokine network. Finally, we investigated that expression of IL-6 and IL-2 receptors in neuronal and oligodendrocytic differentiation, respectively. From these results, we discussed the features of the CNS cytokine network.