Hapten-induced colitis is associated with colonic patch hypertrophy and T helper cell 2-type responses

Abstract

To investigate the potential involvement of T helper (Th)2-type responses in murine models of intestinal inflammation, we used trinitrobenzene sulfonic acid (TNBS)-hapten to induce inflammatory bowel disease in situations where Th1-type responses with interferon (IFN)-gamma synthesis are either diminished or do not occur. Intracolonic administration of TNBS to either normal (IFN-gamma+/+) or Th1-deficient IFN-gamma knockout (IFN-gamma-/-) BALB/c mice resulted in significant colitis. In IFN-gamma-/- mice, crypt inflammation was more severe than in IFN-gamma+/+ mice and was accompanied by hypertrophy of colonic patches with a lymphoepithelium containing M cells and distinct B and T cell zones resembling Peyer's patches. Hapten-specific, colonic patch T cells from both mouse groups exhibited a Th2 phenotype with interleukin (IL)-4 and IL-5 production. TNBS colitis in normal mice treated with anti-IL-4 antibodies or in IL-4(-/-) mice was less severe than in either IFN-gamma+/+ or IFN-gamma-/- mice. Our findings now show that the Th2-type responses in TNBS colitis are associated with colonic patch enlargement and inflammation of the mucosal layer and may represent a model for ulcerative colitis.

Figure 1

The course of TNBS colitis in normal and IFN-γ–deficient mice. (A) Survival rate of mice given TNBS enema. IFN-γ^+/+ (left) or IFN-γ^−/− (right) mice were given 50 (▪), 36 (•), or 25 μg TNBS/g weight (○) intracolonically on days 0 and 7. Each group contained 16–18 mice. The survival rate after administration of 50 μg/g weight was significantly higher in IFN-γ^−/− than in IFN-γ^+/+ mice. (B) Wasting disease in mice given TNBS enema. Left, weight loss of IFN-γ^+/+ mice after administration of ethanol only (□), 36 μg/g weight TNBS–ethanol (○), TNBS–ethanol together with intraperitoneal administration of rat anti– IFN-γ antibody XMG1.2 (▪), or rat IgG as a control (•) on days 0 and 7. Right, weight loss of IFN-γ^−/− mice given TNBS–ethanol (•) or ethanol only (□). The data shown represent average values, and each group contained 5–10 mice. The weights of mice treated with ethanol only were significantly higher than in other groups on days 1, 3, 5, and 10 (left) and on days 1, 3, 7, and 10 (right).

Figure 2

Histologic features of TNBS-induced colitis. (A–C) IFN-γ^+/+ mice; (D–F) IFN-γ^−/− mice. A and D show normal colon with colonic patches, and B, C, E, and F illustrate the colon after a TNBS enema. Original magnification was 10 in A, B, D, and E and 40 in C and F.

Figure 3

Immunohistochemistry of colonic lymphoid follicles of mice with TNBS colitis. The distribution of T (red) and B (green) cells in a colonic patch from an IFN-γ^+/+ (A) or IFN-γ^−/− (C) mouse. Serial sections were stained with PNA in B (IFN-γ^+/+) and D (IFN-γ^−/−). Original magnification was 100.

Figure 4

M cells detected in a colonic lymphoid follicle of an IFN-γ^−/− mouse after TNBS enema. Irregular microvilli with attached bacteria and an underlying macrophage are shown. Bar, 5 μm.

Figure 5

TNBS-specific proliferative responses in IFN-γ^+/+ or IFN-γ^−/− mice with TNBS colitis. (A) Proliferative responses of GALT and SLN cells. Cells were prepared from small intestinal Peyer's patches (white bar), cecal patches (dotted bar), colonic lamina propria lymphocytes (gray bar), colonic patches (black bar), and SLN (hatched bar). The stimulation index was determined as cpm of wells with antigen (TNBS)/cpm of wells without TNBS. The level of [³H]thymidine incorporation for control wells without TNBS was <600 cpm. Values are shown as the average ± 1 SD and are representative of three separate experiments using pooled cells from 3–5 mice in each group. (B) Expression of cytokine-specific mRNA in TNBS-stimulated CD4⁺ T cells. TNBS-stimulated total cell suspensions, which were prepared from SLN or colonic patches (CP) from IFN-γ^+/+ (lane 1) or IFN-γ^−/− (lane 2) mice with TNBS colitis, were cultured for 24 h. CD4⁺ T cells were purified by sorting and subjected to cytokine-specific RT-PCR.

Figure 6

Expression of cytokine-specific mRNA from freshly isolated lamina propria lymphocytes. Total colonic lamina propria lymphocytes or CD4⁺ T cells purified by flow cytometry were prepared on days 0 (before TNBS enema), 1, and 10 and subjected to cytokine-specific RT-PCR. 50 ng of total RNA was used for each reaction. Representative results from three individual experiments are shown.

Figure 7

Histological scores for Th1 and Th2 cytokine-deficient mice with TNBS colitis. (A) IFN-γ–deficient mice; (B) IL-4–deficient mice. Each group included 4–10 mice. Values are shown as the average ± 1 SD. The score of IFN-γ^−/− mice was significantly higher than that of other groups in A (P < 0.02). IL-4^−/− mice and mice treated with anti–IL-4 mAb showed significantly lower values than did normal BALB/c and IFN-γ^−/− mice (P < 0.05). −, rectal administration of ethanol only.