[Brain cytokine network and novel characteristics of microglia]

Microglia, macrophage-like cells in the central nervous system (CNS), are multi-functional cells; they play an important role in the removal of dead cells or their remnants by phagocytosis in CNS degeneration and are one of the important cells in the CNS cytokine network to produce and respond to a variety of cytokines. Although little is known about microglia in the normal CNS, it is obvious that they are quickly activated in all acute pathological events including apoptosis, neurodegeneration and inflammation. Activation of microglia in apoptosis is a double-edged response; under severe apoptotic conditions, microglia act as scavengers removing tissue debris and inducing apoptosis in damaged cells, whereas in more subtle injury they exert a surveillance function and might play a protective role. The transformation of resting microglia into full-blown phagocytes is strictly regulated. To understand the molecular basis of controlling mechanisms of microglia in apoptosis, the study requires in vivo models. For such purpose, we developed the brain-targeting gene delivery system using immortalized microglia, which can facilitate investigation into the roles of particular microglial genes in apoptosis and the gene therapy of several brain disorders.