NFKB1 and Parkinson disease: Additionally, certain conventionally dominant commensal bacteria like Faecalibacterium prausnitzii, which plays a critical role in maintaining immune homeostasis by inhibiting the NFκB signaling pathway and cytokine production and increasing colonic epithelial tight junction proteins, is significantly reduced in both IBD and PD (Laval et al., 2015; Lopez-Siles et al., 2016; Pellegrini et al., 2018).