Airway microbiome linked to asthma severity in children
Much like the gut, skin and mouth, our respiratory system is home to its own unique microbial population, which is being increasingly implicated in a number of diseases, from cystic fibrosis to pulmonary disease. Intriguing new research led by scientists from Washington University School of Medicine in St. Louis has found a link between specific bacterial populations in the upper airways and asthma symptom severity.
Over the last few decades scientists have challenged the old, yet oddly common, misconception that healthy lungs are sterile and free of microorganisms. In fact, our entire respiratory system is home to a diverse community of microbes, and those microbes may play a role in the ebb and flow of asthma symptoms.
This newly published study grew out of a clinical trial following over 200 children with mild to moderate asthma. The goal of the trial was to investigate whether taking a higher dose of inhaled corticosteroids at the earliest signs of trouble could more effectively stifle the oncoming asthma flare-up.
Part of the trial involved collecting nasal mucus samples from the subjects at two points, when their asthma was stable and at the beginning of a symptomatic flare-up. These samples allowed researchers to effectively study the make-up of the upper airway microbiome as a child transitioned from stable respiratory health to an asthma attack.
The results compellingly found a distinct microbiome shift in the upper airway bacterial community as a child transitioned from respiratory health to symptoms of asthma. When a child’s asthma was under control the researchers identified higher levels of Corynebacterium and Dolosigranulum bacteria in the upper airways. As an asthma flare-up loomed the researchers detected increases in Staphylococcus, Streptococcus and Moraxella bacterial populations.
“Our data demonstrated a rapid change of the airway microbiome in the children who transitioned from respiratory health to disease," explains the study’s first author, Yanjiao Zhou. "It is also intriguing to find that the microbiome changing pattern could play an important role in asthma exacerbation."
The researchers are clear in noting the new study does not present causal evidence to suggest these microbial shifts are driving exacerbations in asthma symptoms. It is a little early in the research process to come to that conclusion, but these newly discovered correlations certainly lay the groundwork for a number of novel research directions.
"Though our study can't prove causation, it raises intriguing questions that we plan to pursue,” says Avraham Beigelman, senior author on the study. “If we somehow supplement such patients with what appear to be good bacteria, will they do better? We are interested in studying whether we can deliberately alter the airway microbiome to reduce the risk of worsening asthma symptoms."
The new research was published in the journal Nature Communications.