IL17A and Parkinson disease: More specifically, increase in differentiated Th1 and Th17 cells may directly enhance neuroinflammation by increased release of pro-inflammatory molecules including IL-1, IL-6, IL-17, TNF-α, and IFN-γ [170]; moreover, these cells exacerbate microglia-mediated neurotoxicity by increasing the release of ROS [171]; in this regard, brain infiltration of CD4+ and CD8+ cells was observed in both brain of post-mortem human PD specimens and in mouse PD model [172].