IL1R2 and Arthritis: Indeed, a gain of function mutation in the NLRP3 (NACHT, LRR, and PYD domain-containing protein 3) inflammasome results in the autoinflammatory diseases cryopyrin-associated periodic syndromes (13), and the protective role of IL-1R2 has been shown in a mouse collagen-induced arthritis model where IL-1R2 KO mice have increased arthritis severity (14).