IL17A and periodontitis: found that F. nucleatum, an important causative agent of periodontitis, increases intestinal epithelial permeability, disrupts its integrity by disrupting connexins, promotes the secretion of cytokines TNF-α, IFN-γ, IL-1β, IL-6 and IL-17 and reduces the secretion of anti-inflammatory cytokine IL-10, thereby increasing intestinal inflammation (Liu et al., 2020a).