However, Il25−/−Il1rn−/− mice showed attenuated development of aortitis compared with Il1rn−/− mice (Fig. 4b), indicating that IL-25 contributed to exacerbation—not suppression—of IL-1–, TNF– and IL-17–mediated aortitis in Il1rn−/− mice. This evidence concerns the gene IL1B and aortitis.