IL-10 Receptor or TGF-β Neutralization Abrogates the Protective Effect of a Specific Nondigestible Oligosaccharide Mixture in Cow-Milk-Allergic Mice

Background: Dietary nondigestible, short-chain galacto-, long-chain fructo-, and pectin-derived acidic oligosaccharides (GFAs) lower the effector response in cow-milk-allergic (CMA) mice; and forkhead box P3 (Foxp3)-positive regulatory T cells (Tregs) were shown to contribute to this. Objective: The aim of this study was to assess the contribution of interleukin 10 (IL-10) and transforming growth factor β (TGF-β) to the protective effect of the GFA diet in CMA mice. Methods: Female C3H/HeOuJ mice, 3-4 wk old, were orally sensitized with cholera toxin (Sham) or whey and cholera toxin (Whey) 1 time/wk for 5 consecutive weeks and challenged with whey 1 wk later. The mice were fed a control or 1% GFA (9:2:1) (Whey+GFA) diet starting 2 wk before the first sensitization. In a second experiment, the mice were also injected with αIL-10 receptor (αIL-10r), αTGF-β, or isotype control antibodies 24 h before each sensitization. The acute allergic skin response, anaphylaxis score, whey-specific IgE, mucosal mast cell protease 1 (mMCP-1), and Treg frequency in the mesenteric lymph nodes (MLNs) and intestinal Foxp3, Il10, and Tgfb mRNA expression were determined. Results: In Whey+GFA mice, intestinal Il10, Tgfb, or Foxp3 mRNA expression was 2-10 times higher (P < 0.05) and the MLN Treg frequency was 25% higher compared with Whey mice (P < 0.05). The acute allergic skin response was 50% lower in Whey+GFA mice compared with Whey mice (P < 0.01), and IL-10 receptor (IL-10r) or TGF-β neutralizing antibodies prevented this protective effect (P < 0.001). The Whey mice had higher serum mMCP-1 concentrations and whey-immunoglobulin E (-IgE) levels than Sham mice (P < 0.01), whereas these were not higher in Whey+GFA mice, and neutralizing antibodies partially interfered with these responses. Conclusions: Dietary GFAs enhance the Treg frequency in the MLNs and mucosal IL-10 and TGF-β transcription while suppressing the allergic effector response. Neutralizing antibodies showed that the allergy-protective effect of the GFA diet was mediated by IL-10 and TGF-β in CMA mice.