The combination of oral immunotherapy and a non-digestible oligosaccharide supplemented diet reduced allergic symptoms in a murine cow's milk allergy model

Background: Non-digestible oligosaccharides have been shown to reduce allergic symptoms in murine models of allergy. Objective: To assess the capacity of nondigestible oligosaccharides in supporting the efficacy of oral immunotherapy (OIT) in a murine model for cow's milk allergy. Method: 5-week old female C3H/HeOuJ mice were sensitized intragastrically (i.g.) to the cow's milk protein whey (20 mg whey + 15 μg cholera toxin in PBS) once a week for 5 weeks (d0-d28). Subsequently, mice were fed a 1% short chain fructo-oligosaccharide/long chain fructo-oligosaccharide (9:1) diet (FF) or a control diet (d35-d78). In addition, mice were treated i.g. with 10 mg whey in PBS or PBS alone for 5 days/week for three weeks (d41-d59). The acute allergic skin response, anaphylaxis score and body temperature were measured upon intradermal (i.d.) challenge (d64), mast cell degranulation was measured upon i.g. challenge (d70) and allergen- specific immunoglobulins were monitored during and after OIT and upon intraperitoneal (i.p.) challenge (d77). Cellular parameters were measured in spleen and mesenteric lymph nodes (MLN) at d0, d35, d50, d63, d71 and d78 and in lamina propria (LP) on d63 and d71. Results: Whey sensitized mice receiving OIT+FF showed a decreased acute allergic skin response compared to sensitized mice receiving OIT or FF alone. Body temperature, anaphylactic shock symptoms and mMCP-1 levels in serum were improved in the OIT+FF group compared to sensitized control mice on control diet. During OIT, a rise in whey-specific IgG1, IgG2a and IgA was observed independent of the diet. The increase in whey-specific IgE observed in sensitized mice after i.d. challenge (d64), was prevented in OIT+FF mice. Halfway through immunotherapy (d50), a reduction of IL-5, IL-10 and IFNγ in splenocyte culture supernatant and an increase in the percentage of CD4+ CD25+ FoxP3+ Tregs in the MLN was observed in OIT+FF mice. Directly after OIT (d63), the percentage of activated Th1 cells was increased in MLN and a tendency towards an increased percentage of Tregs was observed in the LP of the OIT+FF group. Total short chain fatty acid content was increased in the caecum of mice on FF diet. Conclusion: OIT in combination with a diet supplemented with non-digestible oligosaccharides effectively reduced allergic symptoms upon i.d. and i.g. challenges. Cellular and cytokine parameters suggest Th2 suppression and the induction of Tregs during immunotherapy in combination with the diet.