TNF and Alzheimer disease: Clustering of activated microglia (Haga et al., 1989; Simard et al., 2006) and astrocytes (Mrak et al., 1996) around amyloid plaques is observed in the AD brain, associated with upregulated expression of a variety of inflammatory cytokines, including interleukin (IL)-1 (Griffin et al., 1995), IL-6 (Bauer et al., 1991), tumor necrosis factor-α (TNF-α; Tarkowski et al., 1999), and transforming growth factor-β (TGF-β; van der Wal et al., 1993).