TNF and Parkinson disease: A meta-analysis of peripheral inflammatory markers revealed elevated interleukin 1 beta (IL-1β), interleukin 2 (IL-2), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10), and C-reactive protein (CRP) levels in patients with PD and atypical Parkinsonisms [4].