TNF and inflammatory bowel disease: Furthermore, this diversity of physiological defects along with the numerous cell-types (T cells, APC and epithelial cells) and cytokines (IL-1, IL-2, IL-6, IL-12, IL-13, IL-17, IL-23, IFN-γ, and TNF-α) involved in inflammation make treating IBD a daunting task (199, 200).