TNF and neurodegenerative disease: Extracellular α-syn stimulates abnormal microglia activation in PD models, accompanied by multiple intracellular signaling pathways involving nuclear factor (NF)-κB, phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT), mitogen-activated protein kinases (MAPKs) [3–6], and a large number of inflammatory factors such as nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and reactive oxygen species (ROS) secretions in vitro, which can lead to further microglia activation and cause a perpetuating cycle of neurotoxicity, aggravating neurodegenerative diseases [3, 7–10].