IL6 and Parkinson disease: Higher levels of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and interferon-gamma (IFN-γ), were found in the cerebrospinal fluids and plasma of PD patients (Muller et al., 1998; Dobbs et al., 1999; Ryul Kim et al., 2018).