Our data confirmed that K. variicola was able to activate microglial cells directly and up-regulate the expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, similar to the ligature microbiome-induced microglial activation but with higher immunogenic reactivity, suggesting that this PD-associated microorganism may have unique virulence factors and could promote more neuroinflammation. Here, TNF is linked to Parkinson disease.