The efficacy of oral and subcutaneous antigen-specific immunotherapy in murine cow’s milk- and peanut allergy models

Abstract

Background Antigen-specific immunotherapy (AIT) is a promising therapeutic approach for both cow’s milk allergy (CMA) and peanut allergy (PNA), but needs optimization in terms of efficacy and safety.AimCompare oral immunotherapy (OIT) and subcutaneous immunotherapy (SCIT) in murine models for CMA and PNA and determine the dose of allergen needed to effectively modify parameters of allergy.MethodsFemale C3H/HeOuJ mice were sensitized intragastrically (i.g.) to whey or peanut extract with cholera toxin. Mice were treated orally (5 times/week) or subcutaneously (3 times/week) for three consecutive weeks. Hereafter, the acute allergic skin response, anaphylactic shock symptoms and body temperature were measured upon intradermal (i.d.) and intraperitoneal (i.p.) challenge, and mast cell degranulation was measured upon i.g. challenge. Allergen-specific IgE, IgG1 and IgG2a were measured in serum at different time points. Single cell suspensions derived from lymph organs were stimulated with allergen to induce cytokine production and T cell phenotypes were assessed using flow cytometry.ResultsBoth OIT and SCIT decreased clinically related signs upon challenge in the CMA and PNA model. Interestingly, a rise in allergen-specific IgE was observed during immunotherapy, hereafter, treated mice were protected against the increase in IgE caused by allergen challenge. Allergen-specific IgG1 and IgG2a increased due to both types of AIT. In the CMA model, SCIT and OIT reduced the percentage of activated Th2 cells and increased the percentage of activated Th1 cells in the spleen. OIT increased the percentage of regulatory T cells (Tregs) and activated Th2 cells in the MLN. Th2 cytokines IL-5, IL-13 and IL-10 were reduced after OIT, but not after SCIT. In the PNA model, no differences were observed in percentages of T cell subsets. SCIT induced Th2 cytokines IL-5 and IL-10, whereas OIT had no effect.ConclusionWe have shown clinical protection against allergic manifestations after OIT and SCIT in a CMA and PNA model. Although similar allergen-specific antibody patterns were observed, differences in T cell and cytokine responses were shown. Whether these findings are related to a different mechanism of AIT in CMA and PNA needs to be elucidated.

Animal models of allergen‐specific immunotherapy in food allergy: Overview and opportunities

“…These findings are opposed to the studies of OIT reviewed above, in which efficacy to oral challenges was lost 2-4 weeks post-treatment and allergic reactivity was sustained in response to IP (systemic) challenge for ovalbumin and whey OIT 12,15. Interestingly, in these models challenges were performed IP 2-5 weeks posttreatment indicating long-term efficacy of therapy.…”

“…The concept of oral tolerance has been studied in rodents since 1910, with early studies describing how oral ingestion of antigen would inhibit later experimental hyperactivity, thus demonstrating that tolerance to ingested food involves active antigen-specific suppression of hypersensitivity. Oral IT (OIT) models have been developed using egg white, 12 ovomucoid (native or heated), 12 ovalbumin, 13 cow's milk proteins (CMPs) 14, 15 and peanut [15][16][17] in sensitized mice. [10,11]).…”

“…18,19 Interestingly, the studies in ovalbuminsensitized mice observed sustained systemic allergen-specific humoral immune responses after therapy, as demonstrated by basophil activation assays and peritoneal mast cells activation. 15 The therapeutic suppression of local gastrointestinal allergic responses was proposed to be mediated by increased IgA levels induced by treatment; however, this hypothesis remains to be formally investigated. 12 Similar results were observed in another study where peanut and whey OIT suppressed mast cell responses following oral challenge, but only mice receiving peanut OIT were protected from intraperitoneal (IP) induced anaphylaxis, indicating allergen-specific differences in therapeutic outcomes and mechanisms.…”

“…Subcutaneous (SC) injections have for decades been used in IT of allergic disease with demonstrated efficacy in asthma, rhinitis and venom allergies. 15 SCIT and OIT were able to suppress anaphylaxis and mast cell degranulation (serum mMCP-1) 38,39 A recent study compared SCIT and OIT in models of cow's milk (whey) and peanut allergy.…”

“…15 Other SCIT mouse models using food allergens support efficacy, but have been conducted without oral or IP allergen provocations for the assessment of clinical food allergy outcomes. Rather, clinical allergen-dependent differences were indicated by the observation that neither SCIT nor OIT could protect from IP-induced anaphylaxis in whey sensitized mice, but peanut-sensitized mice were protected in a therapeutic dose-dependent manner.…”