RelA haploinsufficient mice develop significantly more severe DSS-induced colitis, which is ameliorated by TNF inhibition. (A) Weight loss in DSS-exposed WT, Rela^+/−, and Rela^+/− mice treated with infliximab. n = 5 mice per condition pooled from two independent experiments. ***, P < 0.001; two-way ANOVA. (B) DAI in DSS-treated WT and Rela^+/− mice scores weight loss, stool consistency, and bleeding. n = 5 mice per condition pooled from two independent experiments. *, P < 0.05; Student’s t test. (C) Colon length of DSS-treated WT and Rela^+/− mice at day 10. **, P < 0.01; Student’s t test. (D) Hematoxylin and eosin stain of colonic sections from DSS-treated WT and Rela^+/− mice on day 10. Numbers show the following: 1, severe ulceration; 2, loss of crypt architecture; 3, inflammatory infiltrate; and 4, mild crypt dropout with sparse inflammation. Bars, 500 µm. Data in C and D are from one representative experiment of two independently performed. Bars represent means ± SEM.