TNF and mood disorder: Stress-induced increases in LPS are paralleled by higher levels of proinflammatory cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), which have also been implicated in mood disorders (Bajaj et al., 2012; Shen et al., 2017; Fattorusso et al., 2019).