IL1A and periodontitis: Our research group showed an upregulation of IL-17 with the association of both diseases in rats [13] and it is well known that Th17 plays an important role in the pathogenesis of collagen-induced arthritis, inducing the production of IL-1, TNF-α, IL-6, IL-8, GM-CSF and PGE2 [63, 66–68], as well as in the periodontitis development leading to osteoclastogenesis [69–71].