TNF and Parkinson disease: In PD, dysregulated levels of the GM, Enterobacteriaceae, Prevotellaceae, Verrucomicrobiaceae, Lactobacillus, Porphyromonas, Parabacteroides, Mucispirillum, and Bacteroides fragilis results in an elevated rate of TLR4, IL-1β, IL-2, IL-4, IL-6, IL-13, IL-18, tumor necrosis factor-α (TNF-α), and interferon (IFN)-γ [3].