Dietary long chain n‐3 polyunsaturated fatty acids prevent allergic sensitization to cow's milk protein in mice

<jats:title>Summary</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Cow's milk allergy is one of the most common food allergies in children and no treatment is available. Dietary lipid composition may affect the susceptibility to develop allergic disease.</jats:p></jats:sec><jats:sec><jats:title>Objective</jats:title><jats:p>Assess whether dietary supplementation with long chain n‐3 polyunsaturated fatty acids (n‐3 <jats:styled-content style="fixed-case">LCPUFA</jats:styled-content>) prevents the establishment of food allergy.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Mice were fed a control or fish oil diet before and during oral sensitization with whey. Acute allergic skin response, serum immunoglobulins as well as dendritic cell (<jats:styled-content style="fixed-case">DC</jats:styled-content>) and T cell subsets in mesenteric lymph nodes (<jats:styled-content style="fixed-case">MLN</jats:styled-content>), spleen and/or small intestine were assessed.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The acute allergic skin response was reduced by more than 50% in sensitized mice fed the fish oil diet compared to the control diet. In addition, anti‐whey‐IgE and anti‐whey‐IgG1 levels were decreased in the fish oil group. Serum transfer confirmed that the Th2‐type humoral response was suppressed since sera of fish oil fed sensitized mice had a diminished capacity to induce an allergic effector response in naïve recipient mice compared to control sera. Furthermore, the acute skin response was diminished upon passive sensitization in fish oil fed naïve recipient mice. In addition, the percentage of activated Th1 cells was reduced by fish oil in spleen and <jats:styled-content style="fixed-case">MLN</jats:styled-content> of sham mice. The percentage of activated Th2 cells was reduced in both sham‐ and whey‐sensitized mice. In contrast, whey‐sensitized mice showed an increased percentage of <jats:styled-content style="fixed-case">CD</jats:styled-content>11b+<jats:styled-content style="fixed-case">CD</jats:styled-content>103+<jats:styled-content style="fixed-case">CD</jats:styled-content>8α‐ <jats:styled-content style="fixed-case">DC</jats:styled-content> in <jats:styled-content style="fixed-case">MLN</jats:styled-content> in association with enhanced FoxP3+ regulatory T cells (Treg) in spleen and intestine of fish oil fed whey‐sensitized mice compared to sham mice.</jats:p></jats:sec><jats:sec><jats:title>Conclusions and Clinical Relevance</jats:title><jats:p>Dietary n‐3 <jats:styled-content style="fixed-case">LCPUFA</jats:styled-content> largely prevented allergic sensitization in a murine model for cow's milk allergy by suppressing the humoral response, enhancing local intestinal and systemic Treg and reducing acute allergic symptoms, suggesting future applications for the primary prevention of food allergy.</jats:p></jats:sec>