The role of inflammation and cytokines in brain injury

The original notion that the brain represented an "immune-privileged" organ lacking the capability to produce an inflammatory response to an injury, would appear no longer tenable. Indeed, accumulating evidence during the last decade has shown that the CNS can mount a well-defined inflammatory response to a variety of insults including trauma, ischemia, transplantation, viral infections, toxins as well as neurodegenerative processes. Many aspects of this centrally-derived inflammatory response parallel, to some extent, the nature of such a reaction in the periphery. Through the recent application of molecular biological techniques, new concepts are rapidly emerging as to the molecular mechanisms associated with the development of brain injury. In particular, the importance of cytokines, especially TNF alpha and IL-1 beta, as well as adhesion molecules, has been emphasized in the propagation and maintenance of a CNS inflammatory response. This review will summarize recent observations as to the involvement of these inflammatory mediators in CNS injury and lay claim to the possibility that inhibitors of peripheral inflammation may also be of benefit in treating CNS injuries such as stroke, head trauma, Alzheimer's disease and multiple sclerosis.