TNF and periodontitis: In contrast, the activation of T cells under inflammatory conditions can lead to increased production of RANKL and Tumor Necrosis Factor-α (TNF-α), which promote osteoclast production and bone loss under kinds of inflammatory and autoimmune conditions (Colucci et al., 2004), such as periodontitis (Brunetti et al., 2005), cancer (Colucci et al., 2004) and osteoporosis (Faienza et al., 2009).