TNF and Alzheimer disease: In addition to microglia, astrocytes are activated by tissue damage/injury or Aβ to secrete proinflammatory cytokines (e.g., IL-1, IL-6 or TNF-α), and massive astrogliosis has been reported in the brain of animal models of AD and of patients, with the accumulation of reactive astrocytes around Aβ plaques [22].