TNF and major depressive disorder: Inflammatory cytokines (especially tumor necrosis factor‐α [TNF‐α], interleukin‐1β [IL‐1β], interleukin‐6 [IL‐6], and interleukin‐17 [IL‐17]) have been proposed as modulators for key psychobiological substrates (such as hypothalamic–pituitary–adrenal axis dysregulation and monoamine neurotransmitter metabolism), which are implicated in the pathogenesis of anxiety and depression.10, 11, 12