TNF and myeloid sarcoma: Although LPS-induced neuroinflammation (Figure 2C) depends on peripheral activation of the immune system, blood–brain barrier breakdown, and penetration of peripheral mediators and immune cells into the CNS, i.c.v. injection of TNF-α and IL-1β, 2 proinflammatory cytokines involved in the pathogenesis of MS and known activators of astrocytes (13), resulted in acute CNS-intrinsic inflammation (Figure 2D).