Tolérance induite par l'administration orale d'un allergène du lait de vache (étude des mécanismes cellulaires impliqués)

CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Influence of the route of exposure and the matrix on the sensitisation potency of a major cows’ milk allergen

BACKGROUND: Allergic sensitisation to food may occur through non-gastrointestinal routes such as via skin or lung. We recently demonstrated in mice that cutaneous or respiratory pre-exposures to peanut proteins on intact epithelia induce a Th2 priming and allow subsequent oral sensitization without the use of adjuvant. We then aimed to assess the impact of a similar pattern of exposure to another relevant food allergen, cows' milk. FINDINGS: The humoral and cellular immune response induced in BALB/cJ mice after repeated cutaneous applications on intact skin or after intranasal administration of cows' milk proteins was analysed. In order to assess the potential effect of the food matrix, we used either a purified major cows' milk allergen, β-lactoglobulin (BLG), or whole cows' milk containing the same amount of BLG. We then studied the impact of these pre-exposures on a subsequent oral exposure to milk in the presence or absence of the mucosal Th2 adjuvant, Cholera toxin (CT). Cutaneous applications of milk induced production of BLG-specific IgE and IgG1 in 5 and 8 mice out of 20 respectively, whereas purified BLG alone did not. Intranasal exposure to milk, but not to BLG, led to BLG-specific IgG1 production in 8 out of 20 mice. Notably, cutaneous pre-exposure to milk favours further oral sensitisation without CT, while intra-nasal pre-exposure to BLG prevents further experimental sensitisation. CONCLUSIONS: Altogether, our results thus demonstrated that the immune response induced after non-gastrointestinal exposure to food depends on the allergen, the matrix and the route of exposure

No impact of filaggrin deficiency on the efficacy of epicutaneous immunotherapy in a murine model

Background: Epicutaneous immunotherapy (EPIT®), currently investigated in the treatment of food allergy, needs the integrity of the skin to warrant safety and efficacy. Mutations in the gene encoding the key epidermal protein filaggrin (FLG) are risk factors for peanut allergy and disrupt the skin intergrity. We investigated the association between FLG deficiency and peanut EPIT® efficacy in a murine model. Methods: FLG mutant mice deficient in filaggrin (FLG-/-) or wild-type (WT) mice were sensitized with peanut protein extract (peanut protein) and cholera toxin. Sensitized mice received a patch per week during 8 weeks for EPIT®, using Viaskin®, and were then submitted to sustained peanut oral exposure. We assessed blood humoral and cellular responses and evaluated eosinophil infiltration in the gut mucosa. The different steps of allergen capture and transportation following deposition on the skin was also analyzed in sensitized mice. Results: Sensitization of mice was confirmed by a significant increase of specific Th2 biaised immunological responses. In sensitized mice, EPIT® significantly reduced IgE levels, splenocytes secretion of Th2 cytokines and recruitment of eosinophils in esophagus, compared to sensitized mice without epicutaneous immunotherapy. The allergen applied onto the skin of FLG-/- mice did not undergo passive skin passage or systemic delivery. Instead, the allergen was captured by skin CD205high DCs, which migrated to afferent lymph nodes, as already described in WT mice. Conclusions: EPIT® was efficient and safe in FLG-/- mice, suggesting that in Humans EPIT® keeps efficacy and safety in the presence of loss of function of FLG