T-cell cytokines in injury-induced neural damage and repair

T-cell cytokines are involved in beneficial immune responses, pathological autoimmunity, and tissue inflammation. In this review, we focus on the role of interferon-gamma, interleukin (IL)-2, IL-4, IL-6, and IL-10 in autoimmune diseases such as multiple sclerosis, and primarily "nonimmune" injury of the central nervous system (CNS), in particular focal ischemia and trauma. Resident CNS cells such as microglia and astroglia are additional, and on some occasions major, cellular sources of T-cell cytokines in CNS disease. Collectively, they mediate harmful as well as beneficial functions that depend on the dynamics, cellular source, and compartmental site of their release, the pathophysiological context, and the presence of coexpressed factors. Furthermore, direct neurotoxic and neuroprotective effects of cytokines are evident that are independent from their immunoregulating properties. Whereas these complex interactions are only beginning to be understood, T-cell cytokines nevertheless hold promise as therapeutic targets in a variety of neurological disease conditions.