Conclusively, P. gingivalis, through Mfa1 and FimA fimbriae, promotes immunosuppression and oncogenic cell proliferation, respectively, through a two-hit receptor-ligand process involving DC-SIGN+hi/CXCR4+hi, activating a pAKT+hipFOXO1+hiBIM−lowFOXP3+hi and IDO+hi- driven pathway, likely to impact the prognosis of oral cancers in patients with periodontitis. The gene discussed is IDO1; the disease is periodontitis.