Proinflammatory cytokines such as interferon gamma (IFNγ), tumor necrosis factor-alpha (TNFα), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6) can reach the brain parenchyma and play a role in the development of depressive disorder through regulating synaptic transmission, neuronal excitability, neuronal survival, and synaptic plasticity [46]. The gene discussed is IL1B; the disease is depressive disorder.