IgE-mediated systemic anaphylaxis and impaired tolerance to food antigens in mice with enhanced IL-4 receptor signaling

Abstract

Background: In atopic subjects food ingestion drives the production of IgE antibodies that can trigger hypersensitivity reactions. The IL-4 pathway plays a critical role in this response, and genetic polymorphisms in its components have been linked to allergy.

Objective: We sought to test whether an activating mutation in the IL-4 receptor (IL-4R) α chain enhances allergic responses to a food antigen.

Methods: F709 mice, in which the IL-4Rα immunoreceptor tyrosine-based inhibitory motif is inactivated, were gavage fed with ovalbumin (OVA). Reactions to OVA challenge and immune responses, including antibody production and T(H)2 responses, were assessed.

Results: F709 mice, but not wild-type control animals, sensitized by means of gavage with OVA and either cholera toxin or staphylococcal enterotoxin B, displayed mast cell activation and systemic anaphylaxis on enteral challenge. Anaphylaxis was elicited even in F709 mice enterally sensitized with OVA alone. Bone marrow chimera experiments established that the increased sensitivity conferred by the F709 genotype was mediated mostly by hematopoietic cells but that nonhematopoietic cells also contributed. F709 mice exhibited increased intestinal permeability to macromolecules. The F709 genotype conferred increased OVA-specific IgE but not IgG1 responses, local and systemic T(H)2 responses, and intestinal mast cell hyperplasia compared with wild-type mice. Anaphylaxis was abrogated in F709 mice lacking IgE or the high-affinity receptor for IgE (FcεRI).

Conclusion: Augmented IL-4Rα signaling confers increased intestinal permeability and dramatically enhanced sensitivity to food allergens. Unlike anaphylaxis to injected antigens, which in rodents can be mediated by either IgE or IgG antibodies, the food-induced response in F709 mice is solely IgE dependent.

Figure 1. Allergic responses in F709 mice challenged with OVA following enteral senstitization with OVA with CT

Systemic anaphylaxis was evaluated in orally gavaged mice. (A) Core body temperature, (B) symptom score, (C) diarrhea, (D) serum mMCP-1 levels, (E) Total IgE, (F) OVA-IgE and (G) OVA-IgG1 are shown. n=5–7 mice; data are representative of 3 experiments. * = p<0.05, ** = p<0.01 (student’s t-test); *** = p<0.001 (ANOVA).

Figure 2. Oral anaphylaxis in bone marrow chimera mice

Y709/F709 chimeric mice were enterally sensitized and challenged with OVA (Sal) plus CT. (A) Core body temperature, (B) diarrhea, (C) serum mMCP-1, (D) OVA-IgE and (E) OVA-IgG1 are shown. n=5–7 mice; * = p<0.05, ** = p<0.01 (ttest); *** = p<0.001 (ANOVA).

Figure 3. Anaphylaxis and antibody responses in OVA challenged Y709/IgE^−/− and F709/IgE^−/− mice enterally sensitized with OVA and CT

(A) Anaphylaxis was assessed by measuring changes in body temperature. Following sacrifice, the levels of serum mMCP-1 (B), and anti-OVA IgG1 (C) were determined by ELISA. n=5–7 mice; data are representative of 3 experiments. NS = Not Significant, *** = p<0.001 (ANOVA)

Figure 4. Allergic responses in F709 mice enterally sensitized to OVA in the absence of cholera toxin

Mice were sensitized with OVA in the absence of CT and then challenged with OVA. (A) Core body temperature, (B) diarrhea, (C) serum mMCP-1, (D) OVA-IgE, and (E) OVA-IgG1 are shown. n=5–7 mice; data are representative of 3 experiments. * = p<0.05; *** = p<0.001 by t-test.

Figure 5. Mast cells in the intestines of OVA treated F709 mice and Y709 controls

Mice were treated with OVA and CT or OVA alone. Chloroacetate esterase-reactive cells were identified in sections of jejunum. (A) Jejunal sections. Mast cells appear red. (B) Mast cell counts per 5 low power fields. n=5–7 mice. Data are representative of 3 independent experiments.

Figure 6. Cytokine transcripts in the intestines of mice enterally sensitized to OVA

Mice were treated with OVA+CT or OVA alone. RNA from jejunum was analyzed for cytokine transcripts by RT-PCR. Expression of the following genes was measured. (A) IL-4 (B) IL-13 (C) IL-5 (D) IL-9 (E) IL-10 (F) IFN-γ (G) IL-33.n=5–7 mice; * = p<0.05; ** = p<0.01 by t-test.

Figure 7. Passive IgE-mediated anaphylaxis and intestinal permeability in F709 mice

(A) Core body temperature in mice treated with anti-DNP-IgE and challenged with DNP-HSA. Plasma levels of FITC-dextran (B) and HRP (C) in naïve mice and mice as treated in (A). n=5–7 mice; data are representative of 3 independent experiments. * = p<0.05; ** = p<0.01 by t-test.