TNF and Sacroiliac arthritis: In a slightly different model, overexpression of mouse TNF by deletion of the adenylate-uridylate–rich elements in the murine TNF locus (TNFΔARE mice) induces not only destructive polysynovitis, including sacroiliitis, but also inflammatory bowel disease (Armaka et al., 2008; Jacques et al., 2014; Kontoyiannis et al., 1999).