The chronic production of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interferon (IFN)-γ, interleukin (IL)-1β, and IL-6 is closely related to the etiology of MDD (Laugeray et al., 2016; Noto et al., 2016; Pfau et al., 2018). Here, TNF is linked to major depressive disorder.