Fucoidan-Mediated Covalent Modification Mitigates Allergenicity of Shrimp (<i>Penaeus vannamei</i>) in Mice via Enhanced Intestinal Barrier Function and Antigen Presentation Suppression

Covalent modification is an effective strategy for reducing the allergenicity of single allergens. However, due to the complexity of the food matrix, its application in hypoallergenic food production requires further exploration. The study showed that covalent modification of fucoidan decreased the specific antibody levels, inhibited Th2 cell differentiation, and reduced mast cell degranulation, suggesting that it significantly reduced the allergenicity of <i>Penaeus vannamei</i>. Further analysis showed that covalent modification not only up-regulated the intestinal tight junction proteins expression and improved intestinal mucus secretion but also restored intestinal microbial homeostasis by immunological and 16S rRNA gene sequencing. Additionally, covalent modification inhibited dendritic cell maturation and CD8⁺ T cell differentiation, thereby reducing antigen recognition and presentation, as determined by transcriptome and flow cytometry. Therefore, the covalent modification of fucoidan reduced shrimp allergenicity by enhancing intestinal barrier function and inhibiting antigen presentation. In conclusion, it is a potential strategy for processing hypoallergenic foods.