Fig. 2

In PD patients, proinflammatory cytokines, including IL-6, TNF-α, IL-2, IL-10, IL-1β, and RANTES in the blood, CSF, and the brain tissue, are higher than in the normal population. There are also more active microglia and astrocytes in the brain of PD patients than in normal people. Inflammatory factors secreted by such cells chemotactically attract peripheral inflammatory cells, including monocytes and T and B lymphocytes, which secrete proinflammatory cytokines and antibodies and contribute to neuroinflammation. The neuroinflammation ultimately leads to degeneration of dopaminergic neurons, worsening PD symptoms. Substances released by neuronal degradation, such as DAMPs and α-synuclein, further stimulate brain-resided inflammatory cells and reinforce neurodegeneration. TNF-α tumor necrosis factor α, RANTES regulated on activation normal T-expressed and secreted, IL interleukin, TLR toll-like receptor, DAMPs damage-associated molecular patterns, RBC red blood cell