Serum inflammatory cytokines in the progression of depression.
Frontiers in immunology January 1, 2026 Qing Feng, Zhen Yuan, Qi An et al. 1 citation
Depression involves immune dysregulation, and serum inflammatory cytokines such as IL-1β, IL-6, TNF-α, IFN-γ, and C-reactive protein link peripheral inflammation to brain dysfunction. These cytokines activate innate immune pathways like TLR4, NF-κB, MAPK, and NLRP3 inflammasome, alter tryptophan-kynurenine metabolism via IDO1 and TDO2, impair monoamine neurotransmission, enhance glutamatergic excitotoxicity, reduce BDNF-dependent neuroplasticity, and promote microglia-mediated neuroinflammation. Clinical studies associate cytokine profiles with symptom severity, cognitive dysfunction, suicidality, and illness chronicity. Anti-inflammatory compounds, antidepressants with immunomodulatory effects, and ketamine may work partly by normalizing these cytokine pathways.