June 21, 2012

In the “Dog House”: New Findings in Childhood Asthma Prevention

By Katie Williams, Ivanhoe Health Correspondent

(Ivanhoe Newswire) — Dogs may be cute and cuddly, but they contribute a lot of damage to a household; they chew your shoes, shed fur on your clothes, and knock over priceless objects. Now, a new study shows that one mess they leave behind can actually be beneficial for your children´s´ health.

In a study conducted by researchers from the University of California, San Francisco, and the University of Michigan, Ann Arbor, it was discovered that house dust from homes with dogs appears to protect against infection of a common respiratory virus associated with the development of asthma in children. This virus, respiratory syncytial virus (RSV), is common in infants and can appear as mild to severe respiratory symptoms. Infants who are severely infected have a higher risk of developing childhood asthma.

The study compared three groups of animals: mice fed house dust from homes with dogs before being infected with RSV, mice infected with RSV without exposure to dust and a control group of mice not infected with RSV.

Study researcher Kei Fujimura, PhD, University of California at San Francisco, told Ivanhoe, "We found that the mice not exposed to dust that received the RSV had lung damage, and we also saw that there was mucus buildup inside their lungs and infiltration of inflammatory cells."

The group of mice that were pretreated with the house dust did not exhibit symptoms associated with RSV infection, and they possessed a distinct gastrointestinal bacterial composition compared to animals that were not fed dust. "When we looked at the microbiotic communities, there were two groups that told us that exposure of dust changed the composition of the bacterial communities. Mice pretreated were enriched with bacilli class bacteria. We also looked at the immune response profile of mice and it supported what we found with microscopy work."

Pet ownership has been previously associated with protection against childhood asthma development. Fujimura and colleagues have recently demonstrated that the microbiome (collection of bacterial communities) in house dust from homes that have a cat or dog is compositionally different than house dust from homes without pets.

These findings prompt the idea that microbes within the dog-associated house dust colonize the gastrointestinal tract, control immune responses, and protect the host against RSV. This study´s findings begin the process in determining the identity of the microbial species that protect against RSV. By identifying the specific species that lend this protective effect, there will be more understanding about the role of microbes in defining allergic disease outcomes and could lead to microbial based therapies, eventually reducing the risk of childhood asthma development.

Source: 2012 General Meeting of the American Society for Microbiology, June 2012