In the literature, there are reports suggesting that OPN participates in the pathogenesis of some autoimmune diseases (Cantor 1995; Cho et al. 2009; Denhardt and Guo 1993; Gravallese 2003; Murugaiyan et al. 2008; Ramaiah and Rittling 2008; Scatena et al. 2007; Sodek et al. 2000; Uede 2011). Here, SPP1 is linked to autoimmune disease.