IL-33 promotes gastrointestinal allergy in a TSLP-independent manner

Abstract

Atopic dermatitis (AD) often precedes asthma and food allergy, indicating that epicutaneous sensitization to allergens may be important in the induction of allergic responses at other barrier surfaces. Thymic stromal lymphopoietin (TSLP) and interleukin (IL)-33 are two cytokines that may drive type 2 responses in the skin; both are potential targets in the treatment of allergic diseases. We tested the functional role of IL-33 and the interplay between IL-33 and TSLP in mouse models of atopic march and gastrointestinal (GI) allergy. IL-33-driven allergic disease occurred in a TSLP-independent manner. In contrast, mice lacking IL-33 signaling were protected from onset of allergic diarrhea in TSLP-driven disease. Epithelial-derived IL-33 was important in this model, as specific loss of IL-33 expression in the epithelium attenuated cutaneous inflammation. Notably, the development of diarrhea following sensitization with TLSP plus antigen was ameliorated even when IL-33 was blocked after sensitization. Thus, IL-33 has an important role during early cutaneous inflammation and during challenge. These data reveal critical roles for IL-33 in the "atopic march" that leads from AD to GI allergy.

Figure 1

IL-33 receptor ST2 is required in TSLP-mediated GI allergy. (A) Experimental protocol. (B) Representative photograph of the cecum and colon from indicated mice. (C) Diarrhea occurrence. (D) Diarrhea score. (E) OVA-specific IgE. (F) Intracellular cytokine staining of MLN cells. Plots are gated on CD4⁺CD44^hi cells. Data are representative of two independent experiments with three to four mice per group. Error bars indicate the mean ± SD. ** for p≤ .01; *** for p≤ .001.

Figure 2

Gastrointestinal allergy is ST2-dependent in OVA plus alum model. Mice were sensitized with two OVA/alum intraperitoneal injections and subsequently treated with intragastric OVA for seven consecutive days. (A) Representative photograph of the cecum and colon from indicated mice. (B) Diarrhea occurrence. (C) Intracellular cytokine staining of MLN cells isolated from mice challenged with PBS (upper) and OVA in WT (middle) and Il1rl1 KO mice (lower). Plots are gated on CD4⁺CD44^hi cells. (D) OVA-specific serum IgE levels. Data are representative of two independent experiments with three to four mice per group. Error bars indicate the mean ± SD. ** for p≤ .01; *** for p≤ .001.

Figure 3

IL-33 receptor ST2 is required for intradermal sensitization in TSLP-mediated GI allergy. (A) Experimental protocol. Mice were analyzed on day 15. (B) Representative ILN from MSA+OVA (control) and TSLP+OVA treated mice. (C) ILN cellularity. (D) OVA-specific serum IgE levels. (E) Intracellular cytokine staining of ILN cells. Plots are gated on CD4⁺CD44^hi cells. Data are representative of two independent experiments with three to four mice per group. Error bars indicate the mean ± SD. *** p≤ .001.

Figure 4

Attenuated cutaneous inflammation in K14-Cre⁺Il-33^f/f mice. Mice were treated with TSLP and OVA intradermally four times and analyzed on day 15 as Figure. 3. (A) Representative ILN. (B) ILN cellularity. (C) OVA-specific serum IgE levels. (D) Cytokine production by ILN cells. Data are representative of two independent experiments with three to four mice per group. Error bars indicate the mean ± SD. ** for p≤ .01.

Figure 5

Neutralization of ST2 ameliorates TSLP-mediated GI allergy. (A) Experimental protocol. (B) Diarrhea occurrence. (C) Diarrhea score. (D) Intracellular cytokine staining of MLN cells. Plots are gated on CD4⁺CD44^hi cells. Data are representative of two independent experiments with three mice per group. Error bars indicate the mean ± SD. ** for p≤ .01.

Figure 6

Intradermal administration of IL-33 promotes GI allergy. (A) Experimental protocol. (B) Representative photograph of the cecum and colon from indicated mice. (C) Diarrhea occurrence. (D) OVA-specific serum IgE levels. (E) OVA-specific IgE. (F) Intracellular cytokine staining of MLN cells isolated from mice treated with PBS+OVA (upper) and IL-33+OVA (lower). Plots are gated on CD4⁺CD44^hi cells. (G) mMCP-1 serum levels. Data are representative of two independent experiments with 3-4 mice per group. Error bars indicate the mean ± SD. *** p≤ .001.

Figure 7

Antigen-driven anaphylaxis in IL-33+OVA-sensitized mice. (A) Symptom scores. (B) Body temperature responses after antigen challenge. (C and D) Serum leakage at intestine. Data are representative of two independent experiments with three mice per group. Error bars indicate the mean ± SD. ** for p≤ .01; *** for p≤ .001.

Figure 8

IL-33 mediates GI allergy in a TSLP independent manner. (A) Representative photograph of the cecum and colon from indicated mice. (B) Diarrhea occurrence. (C) Diarrhea score. (D) OVA-specific IgE. (E) mMCP-1 serum levels. Data were pooled from two independent experiments (n=7). (F) Intracellular cytokine staining of MLN cells. Plots are gated on CD4⁺CD44^hi cells. Error bars indicate the mean ± SD.