(Tang and Le, 2016). M1 microglia secrete pro-inflammatory molecules (TNF-α, IL-1β, and IL-6) while M2 microglia release anti-inflammatory molecules (TGF-β and IL-10). However, unbiased global analysis techniques, such as whole-genome transcriptome analysis, indicate that microglia activation is more complex than originally considered, and the classical view of M1 and M2 activation states may not accurately account for activity in vivo (Ransohoff, 2016; Wes et al., 2016). Activated microglia undergo changes in gene expression and function that are specific to the ongoing threat (Keren-Shaul et al., 2017). There is significant heterogeneity in this process, even within an individual brain region, with microglia existing in different functional states (De Biase et al., 2017). Such differences may impart specific roles in the healthy CNS and in neuroinflammatory diseases such as AUD.
