TNF and Chronic colitis: Furthermore, the colon weight/length ratio, the spleen weight, myeloperoxidase (MPO) activity and protein expression of tumor necrosis factor (TNF), IL-1 β, IL-6 and IL-22 were significantly higher in the DSS-treated colons of both wildtype and Muc13−/− mice during acute and chronic colitis (Figure 6E–H), with only a significant increase in TNF protein levels due to Muc13 knockdown after the first cycle of DSS administration compared to the control (Figure 6H).