TNF and colitis: In contrast to the severe clinical symptoms of colitis found in KO mice, WT and KI mice developed more mild clinical symptoms of colitis, including lower colitis activity score (Fig. 6c), decreased colonic expression of proinflammatory cytokines (IL-6, TNF-α, and IL-1β) (Fig. 6d), fewer inflammatory infiltrates, and moderate disruption of mucosal structures (Fig. 6e).