TNF and Parkinson disease: Furthermore, increased levels of inflammatory cytokines including interleukin 1-beta (IL-1β), interleukin-6 (IL-6), interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α) have been found within brain parenchyma and human cerebrospinal fluid (CSF) of PD patients [7–9].