IL18 and colitis: However, on the other hand, IL-18 is thought to promote the ability of colitis by inducing inflammatory mediators such as TNFα and chemokines (Sivakumar et al., 2002), inhibition of IL-18 has also been shown to trigger protection in experimental colitis, supporting the role of IL-18 in exacerbating colitis (Siegmund et al., 2001).