Synbiotic Combination of <i>Lactiplantibacillus plantarum</i> and Fructo-Oligosaccharide Alleviates Soy Protein-Induced Food Allergies in Mice by Modulating the Gut Microbiota and Its Metabolisms

Oral administration of synbiotics is a highly effective approach to improve food allergies through the modulation of gut microbiota. Therefore, the effects of synbiotics composed of <i>Lactiplantibacillus plantarum</i> (Lp) and fructo-oligosaccharide (FOS) on soybean-sensitized mice were explored in this study focusing on the gut microbiota and metabolisms. The results indicated that Lp-FOS intervention significantly alleviated allergic symptoms, reduced the IgE, IgG1, and mMCP-1 levels, restored the balance of Th1/Th2 and Tregs/Th17, and enhanced intestinal barrier integrity. 16S rDNA microbiome sequencing revealed that Lp-FOS increased the <i>Lachnospiraceae</i> and <i>Lactobacillus</i> proportions and reduced the <i>Desulfovibrionaceae</i> and <i>Muribaculaceae</i> proportions. Nontargeted metabolomics further demonstrated that Lp-FOS improved gut metabolic disorders by modulating key pathways involved in amino acid metabolism, cofactor and vitamin metabolism, and lipid metabolism, with a notable enhancement in tryptophan metabolism. Collectively, this study confirmed that Lp-FOS could mitigate soybean allergy by regulating the immune system, gut microbiota, and metabolic pathway. This study will offer novel insights into developing synbiotic-based interventions against food allergies.