House Dust Mediates Gut Microbiome Lactobacillus johnsonii Enrichment and Immune Defense Against Airway Allergens [Set3]

Exposure to dogs in early infancy has been shown to reduce the risk of childhood allergic disease development and dog-ownership is associated with a distinct house dust microbial exposure. Here we demonstrate, using murine models, that exposure of mice to dog-associated house dust protects against ovalbumin or cockroach allergen mediated airway pathology. Protected animals exhibited significant reductions in the total number of airway T cells, down-regulation of Th2-related airway responses as well as mucin secretion. Following house dust exposure, the cecal microbiome of protected animals was extensively restructured with significant enrichment of, amongst others, Lactobacillus johnsonii. Supplementation of wild type animals with L. johnsonii protected them against both airway allergen challenge or infection with respiratory syncytial virus. L. johnsonii mediated protection was associated with significant reductions in the total number and proportion of activated CD11c+/CD11b+ and CD11c+/CD8+ cells, as well as significantly reduced airway Th2 cytokine expression. Our results reveal that exposure to dog-associated household dust results in protection against airway allergen challenge and a distinct GI microbiome composition. Moreover the study identifies L. johnsonii as a pivotal species within the gastrointestinal tract capable of influencing adaptive immunity at remote mucosal surfaces in a manner that is protective against a variety of respiratory insults.