TNF and colitis: The pathogenesis of colitis caused by DSS is unclear, but can be summarized as the following mechanisms: (1) reduction in resistance and death of mucosal epithelial cells due to increased osmosis of the colonic mucosa; (2) intestinal-specific T cell induction of immune inflammatory response; (3) increased expression of cytokines, such as TNF-α, IFN-γ, and IL-10; and (4) changes in the intestinal bacterial environment.