Involvement of inflammatory cytokines in central nervous system injury.

Pro-inflammatory cytokines, interleukin (IL) 1 and tumor necrosis factor (TNF), possess a wide range of biological actions in various tissues. In recent years, there has been increasing evidence that these cytokines are involved in inflammatory reactions in central nervous system (CNS) diseases. Although many studies have demonstrated that IL-1, TNF, and their mRNA are up-regulated in the CNS after injury, the functional roles of these cytokines in the injury are far from completely understood. Overexpression of these cytokines, such as observed during the early stage of injury, can be harmful for the injured tissue. However, low levels of these cytokines, observed during the recovery stage after injury, can enhance repair processes of the injured tissues.