Chronically activated microglia, increased cell density and hyper-ramified morphology (Dubbelaar et al., 2018), and the enhanced release of pro-inflammatory cytokines, e.g., TNF-α, IL-1β, and IL-18, are observed in response to stress, major depression, or AD, leading to disease progression and brain damage (Pickering and O’Connor, 2007). Here, IL1B is linked to major depressive disorder.