Bifidobacterium longum and Lactobacillus plantarum alleviate house dust mite allergen-induced allergic rhinitis by regulating IL-4, IL-5, and IL-10 expression

We examined the effects of Bifidobacterium longum IM55, Lactobacillus plantarum IM76, and their (1:1 and 1:9) mixtures (PMs) on house dust mite allergen extract (HDMA)-induced allergic rhinitis (AR) in mice. Oral administration of IM55, IM76, or PM significantly suppressed HDMA-induced allergic nasal symptoms, IL-4 and IL-5 expression in the nasal mucosa, bronchoalveolar lavage fluid (BALF), and blood, and IgE level in blood. They suppressed HDMA-induced eosinophil, mast cell, and Th2 populations in BALF while the regulatory T cell population and IL-10 expression were increased. Treatment with IM55, IM76, or PM significantly reduced HDMA-induced IL-4, IL-5, IL-13, and eosinophil peroxidase expression and increased IL-10 expression in the colon. Furthermore, their treatments suppressed HDMA-induced Proteobacteria population and Proteobacteria to Bacteroidetes ratio in the gut microbiota. In conclusion, IM55 and IM76 may mitigate AR by suppressing IL-4, IL-5, and IL-13 expression and inducing IL-10 expression through the inhibition of gut Proteobacteria population.