Moreover, in vitro studies have shown that GFs challenged with subgingival biofilms promoting periodontitis at lower levels display increased gene expression of NLRP3, caspase-1, ASC, AIM2, IL-1β, and IL-18, whereas GFs display decreased gene expression of these factors when challenged with higher levels of subgingival biofilm (Bostanci et al., 2011). Here, IL18 is linked to periodontitis.