Upregulation of pro-inflammatory cytokines has also been reported in PD, including increased expression of tumour necrosis factor α (TNFα), interleukin 1β (IL-1β), and interferon γ (IFNγ) in the substantia nigra, and upregulation of interleukin 6 (IL6) and interleukin 2 (IL2) in the striatum [33, 55–57]. This evidence concerns the gene IL6 and Parkinson disease.