Exposure to food allergens through inflamed skin promotes intestinal food allergy through the thymic stromal lymphopoietin-basophil axis

Abstract

Background: Exposure to food allergens through a disrupted skin barrier has been recognized as a potential factor in the increasing prevalence of food allergy.

Objective: We sought to test the immunologic mechanisms by which epicutaneous sensitization to food allergens predisposes to intestinal food allergy.

Methods: Mice were epicutaneously sensitized with ovalbumin or peanut on an atopic dermatitis-like skin lesion, followed by intragastric antigen challenge. Antigen-specific serum IgE levels and T(H)2 cytokine responses were measured by ELISA. Expression of type 2 cytokines and mast cell proteases in the intestine were measured by using real-time PCR. Accumulation of basophils in the skin and mast cells in the intestine was examined by using flow cytometry. In vivo basophil depletion was achieved by using diphtheria toxin treatment of Baso-DTR mice. For cell-transfer studies, the basophil population was expanded in vivo by means of hydrodynamic tail vein injection of thymic stromal lymphopoietin (TSLP) cDNA plasmid.

Results: Sensitization to food allergens through an atopic dermatitis-like skin lesion is associated with an expansion of TSLP-elicited basophils in the skin that promote antigen-specific T(H)2 cytokine responses, increased antigen-specific serum IgE levels, and accumulation of mast cells in the intestine, promoting the development of intestinal food allergy. Critically, disruption of TSLP responses or depletion of basophils reduced the susceptibility to intestinal food allergy, whereas transfer of TSLP-elicited basophils into intact skin promoted disease.

Conclusion: Epicutaneous sensitization on a disrupted skin barrier is associated with accumulation of TSLP-elicited basophils, which are necessary and sufficient to promote antigen-induced intestinal food allergy.

Keywords: Food allergy; IgE; atopic dermatitis; basophils; epicutaneous sensitization; mast cells; thymic stromal lymphopoietin.

FIG. 1

Epicutaneous sensitization promotes antigen-induced food allergy. A, Experimental protocol. B, TSLP protein in the skin. C, Allergy score. D, OVA-specific serum IgE levels. E, H&E staining from the jejunum. Scale bar: 100 μm. Arrows: tissue-infiltrating granulocytes. F, Type-2 cytokine expression in the jejunum. G, Frequencies of mast cells in the lamina propria. H, Jejunal Mcpt1 and Mcpt2 expression. N = 3–4 per group. Data are representative of three independent experiments. ND: no disease.

FIG. 2

TSLP-TSLPR responses mediate antigen-induced food allergy. A, Experimental protocol. B, Allergy score. C, OVA-specific serum IgE levels. D, H&E staining from the jejunum. Scale bar: 100 μm. Arrows: tissue-infiltrating granulocytes. E, Type-2 cytokine expression in the jejunum. F, Frequencies of mast cells in the lamina propria. G, Jejunal Mcpt1 and Mcpt2 expression. N = 3–4 per group. Data are representative of three independent experiments. ns: not significant.

FIG. 3

TSLP is sufficient to promote antigen-induced intestinal food allergy. A, Experimental protocol. B, Allergy score. C, OVA-specific serum IgE levels. D, H&E staining from the jejunum. Scale bar: 100 μm. Arrows: tissue-infiltrating granulocytes. E, Type-2 cytokine expression in the jejunum. F, Frequencies of mast cells in the lamina propria. G, Jejunal Mcpt1 and Mcpt2 expression. N = 3 mice per group. Data are representative of three independent experiments.

FIG. 4

AD-like skin lesions are associated with the accumulation of TSLP-elicited basophils in the skin. A, Experimental protocol. B, Frequencies of basophils in the skin. C, H&E staining from the skin. Scale bar: 100 μm. D, Ear thickness measurement. E, Th2 cytokine responses in antigen re-stimulated skin-draining lymph nodes. N = 3–4 per group. Data are representative of three independent experiments. nd: not detected.

FIG. 5

TSLP-elicited basophil responses regulate antigen-induced food allergy. A, Experimental protocol. B, Allergy score. C, OVA-specific serum IgE levels. D, H&E staining from the jejunum. Scale bar: 100 μm. Arrows: tissue-infiltrating granulocytes. E, Type-2 cytokine expression in the jejunum. F, Frequencies of mast cells in the lamina propria. G, Jejunal Mcpt1 and Mcpt2 expression. N = 3–5 per group. Data are representative of three independent experiments.

FIG. 6

TSLP-elicited basophils are sufficient to promote intestinal food allergy. A, Experimental protocol. B, Allergy score. C, OVA-specific serum IgE levels. D, H&E staining from the jejunum. Scale bar: 100 μm. Arrows: tissue-infiltrating granulocytes. E, Type-2 cytokine expression in the jejunum. F, Frequencies of mast cells in the lamina propria. G, Jejunal Mcpt1 and Mcpt2 expression. N = 3 per group. Data are representative of three independent experiments.