Our analysis found that anti-CD40-induced colitis mice displaying decreased AhR-mediated α-defensin 1 induction exhibited increased body weight loss (Figure 6b), colon shortening (Figure 6c), macroscopic colitis score (Figure 6d), increased serum FITC-dextran (Figure 6e), a marker for gut permeability, increased colonic (Figure 6f,g) and histopathological colitis scores (Figures 6h,i) as a measure, based on marked crypt architecture damage, inflammatory cell infiltration and ulceration. This evidence concerns the gene CD40 and colitis.