TNF and periodontitis: Similarly, macrophages in periodontitis are often induced towards a pro-inflammatory M1 phenotype, secreting large amounts of cytokines such as interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and interleukins (IL) (e.g., IL-6, IL-12), along with matrix metalloproteinases (MMPs), further intensifying the inflammation (19).