Figure 4.

Epithelial expression of TNF in DSS- and psiTNF-treated mice

(A and A′) Mice treated with vehicle show minimal expression of TNF-α in the distal colon, limited to the apical surface of mucosal epithelial cells (A′, arrowheads). (B and B′) After 7 days of DSS treatment, TNF production increases significantly, where every cell in the epithelial lining of the intestinal mucosa (B, dashed line) shows strong expression of TNF. (C and C′) Animals treated simultaneously with psiTNF plasmid (GFP) and DSS exhibit moderate levels of TNF expression. In contrast to animals not treated with the plasmid, distal colon of psiTNF-treated mice display only non-continuous patches of epithelial TNF expression (C′, encircled areas).