Children who grow up with dogs in the house have long been known to have a decreased risk of allergies and asthma. Now new research published in the journal Proceedings of the National Academy of Sciences indicates that changes in gut microbes are responsible for the safeguard that dogs provide to young children.
To study the effects of dogs on asthma and allergy risk, researchers from the University of California-San Francisco (UCSF) and the University of Michigan used a mouse study. The researchers exposed the mice to dog-associated dust. Dog-associated dust is the dust found in homes with dogs that contains canine dander and other particulates from dogs.
The mice exposed to the dog dust experienced a reshaping of their gastrointestinal microbiome, or the community of microbes in their gut.
When the mice were then exposed to cockroach or protein allergens, both of which cause inflammatory responses in the lungs that are associated with asthma, the mice exposed to the dog dust exhibited significantly reduced inflammatory responses compared to mice not exposed to dog-related dust.
The researchers additionally singled out one species of bacteria in the dog dust called Lactobacillus johnsonii, which, when fed to the mice, protected against airway inflammation attributed to allergens and respiratory syncytial virus (RSV) infection. RSV infection has previously been linked to an increased risk of asthma.
Furthermore, although exposure to Lactobacillus johnsonii alone provided some protection against allergies, infections, and asthma, exposure to the full microbial catalog in dog-associated dust resulted in increased levels of protection.
In other words, full species of bacteria are likely needed for full protection in the airway.
Professor Susan Lynch, lead study author from the Division of Gastroenterology at UCSF, states that she is convinced that “the composition and function of the gut microbiome strongly influence immune reactions and present a novel avenue for development of therapeutics for both allergic asthma and a range of other diseases.”
The results of this study indicate that changes to gut microbes most likely account for the protection that dogs offer young children against allergies and asthma.
Furthermore, Professor Lynch believes that these findings have implications for future studies: “Gut microbiome manipulation represents a promising new therapeutic strategy to protect individuals against both pulmonary infection and allergic airway disease.”
Dogs really are man’s best friend.
Dogs in the House Protect Against Asthma, Infection: http://www.medicalnewstoday.com/articles/270403.php
House Dust Exposure Mediates Gut Microbiome Lactobacillus Enrichment and Airway Immune Defense Against Allergens and Virus Infection: http://www.pnas.org/content/early/2013/12/13/1310750111.full.pdf+html?sid=97f44f8a-1e18-4adc-8af3-ddce881f2e45
Bailey the Shih-Tzu Running in the Park: http://www.freeimages.com/photo/1433430