IL-5, IL-9, IL-13, and IL-33 for UC, IL-10, IL-12, IL-27, and interferon (IFN)-γ for CD, and IL-6, IL-12, IL-17, IL-21, IL-23, and TNF-α for both IBD types are cytokines linked to disease etiology (120). Here, TNF is linked to irritable bowel syndrome.