Studies have shown that nicotinamide phosphoribosyl transferase (NAMPT) expression is upregulated in the periodontal ligament tissues of RA mice, resulting in elevated levels of proinflammatory cytokines (IL‐6), chemokines (IL‐8, CCL5), and inflammatory mediators such as COX‐2, MMP‐1, and MMP‐3 in periodontal ligament cells.212. This evidence concerns the gene IL6 and rheumatoid arthritis.