TNF and Alzheimer disease: This idea is supported by the observations that MSC transplantation into AD mouse models reduces the release of proinflammatory cytokines such as TNF-α, IL-1β, and IL-6 from the activated microglia and astrocytes [14,54] and changes the polarization of microglia from the proinflammatory M1 phenotype to the immunomodulatory M2 phenotype [27].