The contribution of
inflammation to the pathogenesis of several
nervous system disorders has long been established. Other observations, however, indicate that both inflammatory cells and mediators may also have beneficial functions, assisting in repair and recovery processes. There is compelling evidence to indicate that in the injured nervous system, as in other tissues, macrophages are needed at an early stage after injury in order for healing to take place. Likewise, activated T cells of a particular specificity can reduce the spread of damage. This
neuroprotective effect of T cells may be caused, at least in part, by the production of
neurotrophic factors such as neurotrophin-3 or
brain-derived neurotrophic factor. Interestingly, recent findings indicate that immune cells are able to produce a variety of
neurotrophic factors which promote neuronal survival and may also mediate anti-inflammatory effects. Numerous
cytokines are induced after
nervous system injuries. Some
cytokines, such as
TNF-alpha,
IL-1 and IFN-gamma, are well known for their promotion of inflammatory responses. However, these
cytokines also have immunosuppressive functions and their subsequent expression also assists in repair or recovery processes, suggesting a dual role for some pro-inflammatory
cytokines. This should be clarified, as it may be crucial in the design of therapeutic strategies to target specific
cytokine(s). Finally, there is a growing body of evidence to show that autoreactive
IgM antibodies may constitute an endogenous system of tissue repair, and therefore prove of value as a therapeutic strategy. Available evidence would appear to indicate that the inflammatory response observed in several neurological conditions is more complex than previously thought. Therefore, the design of more effective
therapies depends on a clear delineation of the beneficial and detrimental effects of
inflammation.