Abstract
Oral immunotherapy (OIT) is a promising therapeutic approach to treat food allergic patients. However, there are some concerns regarding its safety and long-term efficacy. The use of non-digestible oligosaccharides might improve OIT efficacy since they are known to directly modulate intestinal epithelial and immune cells in addition to acting as prebiotics. To investigate whether a diet supplemented with plant-derived fructo-oligosaccharides (FOS) supports the efficacy of OIT in a murine cow's milk allergy model and to elucidate the potential mechanisms involved. After oral sensitization to the cow's milk protein whey, female C3H/HeOuJ mice were fed either a control diet or a diet supplemented with FOS (1% w/w) and received OIT (10 mg whey) 5 days a week for 3 weeks by gavage. Intradermal (i.d.) and intragastric (i.g.) challenges were performed to measure acute allergic symptoms and mast cell degranulation. Blood and organs were collected to measure antibody levels and T cell and dendritic cell populations. Spleen-derived T cell fractions (whole spleen- and CD25-depleted) were transferred to naïve recipient mice to confirm the involvement of regulatory T cells (Tregs) in allergy protection induced by OIT + FOS. OIT + FOS decreased acute allergic symptoms and mast cell degranulation upon challenge and prevented the challenge-induced increase in whey-specific IgE as observed in sensitized mice. Early induction of Tregs in the mesenteric lymph nodes (MLN) of OIT + FOS mice coincided with reduced T cell responsiveness in splenocyte cultures. CD25 depletion in OIT + FOS-derived splenocyte suspensions prior to transfer abolished protection against signs of anaphylaxis in recipients. OIT + FOS increased serum galectin-9 levels. No differences in short-chain fatty acid (SCFA) levels in the cecum were observed between the treatment groups. Concisely, FOS supplementation significantly improved OIT in the acute allergic skin response, %Foxp3+ Tregs and %LAP+ Th3 cells in MLN, and serum galectin-9 levels. FOS supplementation improved the efficacy of OIT in cow's milk allergic mice. Increased levels of Tregs in the MLN and abolished protection against signs of anaphylaxis upon transfer of CD25-depleted cell fractions, suggest a role for Foxp3+ Tregs in the protective effect of OIT + FOS.
Highlights
The prevalence of food allergies has been increasing in recent decades, in particular in Western countries
Oral Immunotherapy (OIT) + FOS induced protection against these allergic symptoms: the acute allergic skin response was reduced after OIT + FOS compared to FOS (p = 0.0048) or OIT alone (p = 0.023) (Figure 2A), indicating the improved efficacy of the combination strategy
OIT + FOS protected against the anaphylaxis-associated drop in body temperature compared to sensitized control mice (p = 0.0045) and FOS no IT (p = 0.0123) (Figure 2B) and both OIT and OIT + FOS reduced the severity of anaphylaxis symptoms (Figure 2C) compared to the sensitized control (p = 0.0322 and p = 0.0002, respectively)
Summary
The prevalence of food allergies has been increasing in recent decades, in particular in Western countries. The strategy to induce desensitization and/or oral tolerance to food allergens via antigen-specific immunotherapy (AIT) has been studied extensively. Oral Immunotherapy (OIT) with milk, peanut, and hen’s egg effectively desensitized food allergic patients in randomized controlled clinical trials, measured as the absence of clinical symptoms upon food challenge [3]. Safety concerns are relevant, since adverse events ranging from mild to near-fatal reactions have been reported [4]. 95% of cow’s milk allergic children subjected to OIT experienced adverse events during treatment, including 25% suffering from severe, frequent, and unpredictable reactions [5]. Oral immunotherapy (OIT) is a promising therapeutic approach to treat food allergic patients. Aim: To investigate whether a diet supplemented with plant-derived fructooligosaccharides (FOS) supports the efficacy of OIT in a murine cow’s milk allergy model and to elucidate the potential mechanisms involved
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