Figure 2. Intestinal epithelial-specific occludin KO limits epithelial apoptosis and overall severity of TNBS colitis.

A. TNBS induced wasting and loss of normal fur texture in WT (Ocln^f/f) mice. At day 4 after rectal TNBS instillation these features were almost undetectable in occludin KO^IEC (Ocln^f/f x vil-Cre) mice. Bar = 1cm.

B. TNBS-induced increases in disease activity scores were attenuated in occludin KO^IEC mice (Day 4 data, n = 5 WT, 10 KO^IEC).

C. Histopathology shows severe damage in TNBS-treated WT, but not occludin KO^IEC, mice. Bar = 50μm.

D. TNBS-induced increases in intestinal permeability to 4 kD dextran were markedly attenuated in occludin KO^IEC, relative to WT, mice (n ≥ 5 per group).

E. TNBS-induced Il6, Il1b, Cxcll, and Tnf upregulation in WT, but not occludin KO^IEC, mice (n = 5 per group).

F. TNBS increased colonic epithelial proliferation similarly in WT and occludin KO^IEC mice (n = 3 per group). Representative photomicrographs are shown in Suppl. Fig 3B.

G. TNBS increased numbers of TUNEL-positive cells in WT, but not occludin KO^IEC, mice (n = 3 per group). Representative photomicrographs are shown in Suppl. Fig 3B.

H. TNBS increased numbers of ISOL-positive cells in WT, but not occludin KO^IEC, mice (n = 3 per group).

I. TNBS increased numbers of cleaved caspase-3-positive cells in WT, but not occludin KO^IEC, mice (n = 3 per group). Representative photomicrographs are shown in Suppl. Fig 3B.

Statistical analyses by Student’s f-test or one-way ANOVA with Bonferroni post-test. *, P<0.05; **, P<0.01.