TNF and colitis: Consistent with reports from adult-phase studies 2, OD during adolescence caused colitis characterized by upregulated mRNA expression of proinflammatory cytokines, including tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and monocyte chemoattractant protein-1 (MCP-1), relative to mice on normal diet (Figure 3E-G).