IL1B and major depressive disorder: Expression of the microglial marker IBA-1 and inflammatory cytokines (IL1β, TNFα, BDNF) are up-regulated in the brain of patients with major depression (Rahman and Alzarea 2019; Torres-Platas et al. 2014) and in animal models of depressive-like behavior (Kreisel et al. 2014; Tomaz et al. 2020).