IL1B and major depressive disorder: Hyperactivated microglia negatively affect neuroimmune homeostasis by overexpressing proinflammatory cytokines (e.g., TNF-α and IL-1β), class I and II major histocompatibility complex antigens, and neurotoxic molecules (e.g., RNS/ROS, superoxide anions, large amounts of nitric oxide, peroxynitrite, etc.), all of which lead to altered neuroinflammatory pathways, resulting in depression [19].