During the course of brain injury and inflammation there is an increased secretion of neurotrophic substances by astrocytes. We have examined the effect of the Th2-derived cytokine IL-10 and the Th1-derived cytokines Il-2 and IFN-γ on the secretion of NGF by mouse astrocytes. IL-10 induced a dose-dependent increase in NGF secretion which was blocked by anti-IL-10 antibody. In contrast, the Th1-derived cytokines IFN-γ and IL-2 did not induce NGF synthesis. Moreover, INF-γ completely inhibited the increase in NGF secretion induced by IL-10 whereas it had no effect on the induction of NGF by TNF-α. These results indicate that IL-10 similarly to other Th2-derived cytokines may provide a neurotrophic support to injured neurons via the induction of NGF synthesis, whereas the Th1-derived cytokine IFN-γ antagonizes this effect.
