Interleukin-1 beta promotes repair of the CNS

Interleukin-1 beta (IL-1 beta) is a proinflammatory cytokine associated wit h the pathophysiology of demyelinating disorders such as multiple sclerosis and viral infections of the CNS. However, we demonstrate here that IL-1 be ta appears to promote remyelination in the adult CNS. In IL-1 beta (-/-) mi ce, acute demyelination progressed similarly to wild-type mice and showed p arallel mature oligodendrocyte depletion, microglia-macrophage accumulation , and the appearance of oligodendrocyte precursors. In contrast, IL-1 beta (-/-) mice failed to remyelinate properly, and this appeared to correlate w ith a lack of insulin-like growth factor-1 (IGF-1) production by microglia- macrophages and astrocytes and to a profound delay of precursors to differe ntiate into mature oligodendrocytes. Thus, IL-1 beta may be crucial to the repair of the CNS, presumably through the induction of astrocyte and microg lia-macrophage-derived IGF-1.