Commensal probiotic provides long-term protection in a murine model of allergic lung disease by altering the host microbiota

Abstract

Abstract The incidence of allergic diseases is increasing, with house dust mite allergy, afflicting up to 20% of the population in developed countries. House dust mites (HDM) are a common allergen that can be difficult to avoid and triggers allergic reactions, including wheezing and shortness of breath. Bacillus subtilis is a gut-associated commensal probiotic that can prevent murine HDM-induced allergic lung inflammation. We exposed C57Bl/6 mice to B. subtilis via oral gavage and challenged with intranasal HDM for up to 8 weeks. We found that pretreatment with B. subtilis was able to provide protection from eosinophil infiltration, measured in bronchial alveolar lavage fluid (BALF), for 3 weeks. This loss of protection correlated with an increase in the eosinophil chemoattractant CCL24 levels in the BALF and reduced abundance of the bacterial phylum Verrucomicorbiota in collected feces. Additionally, we found that B. subtilis treatment altered the bacterial composition by increasing the abundance of the bacteria phylum Bacteroidetes. These results support B. subtilis as a prophylactic for preventing allergic lung disease and highlights that protection can last up to 3 weeks. This work also expands our understanding of how B. subtilis mediates protection and that in addition to modifying the immune system, it is also altering the host microbiota. This work is supported by start-up funds and core facility outsourcing funds from Midwestern University.