Fig. 2

Mechanisms and roles of T cells on microglia cells in PD. The damaged BBB allows T lymphocytes, including Tregs, to enter the brain in the early stages of the disease, and Tregs can also play a role in immune regulation (left of the illustration). The immunosuppressive properties of Tregs gradually decrease as the disease progresses (middle and late stage), breaking the homeostasis between Tregs and Teffs. Teffs, in particular, hasten the activation of microglia cells by secreting various proinflammatory factors, which hastens the onset of neurodegeneration (right of the illustration). The images in this Figure were downloaded from ProteinLounge.com with permission to use them