TNF and periodontitis: Among the 400 genes significantly upregulated in DAC-treated GFs infected with P. gingivalis, we identified several pro-inflammatory cytokines and chemokines, including CCL20, CCL5, CCL8, CCL13, TNF, IL1A, IL18, IL33, and CSF3. Elevated levels of many of these mediators have been detected in gingival crevicular fluid or tissue from patients with periodontitis (43), and their activity contributes to the chronicity of inflammation and alveolar bone resorption.