Alcohol-induced TLR signaling culminates in increased expression of pro-inflammatory immune genes via NF-κB activation (Fig. 1). Although NF-κB is expressed in most cells, it is transcriptionally active in brain primarily in glia [37]. Ethanol treatment activates brain microglia and NF-κB-induced transcription of pro-inflammatory immune genes, increasing expression of cytokines, proteases, and oxidases. For example, chronic ethanol increases expression of TNFα, monocyte chemoattractant protein (MCP-1), interleukin-1β (IL-1β), interleukin-6 (IL-6), and NOX (NADPH oxidase) in mouse and rat brain slice cultures [24,38,39]. Increased expression of IL-1β[40] and MCP-1 (CCl2) [20] was also found in post-mortem brains from alcoholics. Chronic ethanol treatment in rat brain cultures increases HMGB1 and TLRs in vitro in agreement with increased in vivo protein expression of HMGB1 and TLRs in mouse brain following ethanol treatment and in post-mortem brains from alcoholics [19]. Increased frontal cortical HMBG1, TLR3, and TLR4 were also observed in rats exposed to intermittent alcohol using a binge-drinking model [41]. A role for cytokines and NF-κB in innate immune gene expression was reported in rat brain slice cultures given that blockade of the cytokine TNFα
