TNF and colitis: TNBS administration induces transmural colitis that is driven by a Th1-mediated immune response [13,14,17] that is characterized by the infiltration of CD4 cells, neutrophils, and macrophages into the lamina propria and the secretion of cytokines [14] The most common cytokines are tumor necrosis factor (TNF)-α and interleukin (IL)-12.