Microbes are well known to form entire communities in our guts – or microbiomes, but less is known about the communities we have in our lungs. Researchers from Washington University School of Medicine in St. Louis investigated the correlation between microbial colonisation in the upper airway and the severity of asthma symptoms. Published in Nature Communications, the researchers investigated if the airway microbiome plays a role in severity of asthma symptoms, seeking a potential way to reduce the severity if so.

Asthma is a very common condition worldwide with more than 1 million cases per year in the UK alone. According to the Asthma and Allergy Foundation of America, asthma is the most common reason for children to miss school in the US. It’s a recurring condition affecting the airways of the lungs, and current treatments help to manage the condition but there is no known cure.

The researchers collected nasal mucus samples from 214 children aged between 5 and 11 years with mild to moderate asthma at two time-points within one year: one when their asthma was well controlled, and the other during time of early loss of asthma control. The researchers discovered that the microbiomes in these samples were different between the two time-points.

During early loss of asthma control, the children were more likely to have pathogenic bacteria such as Streptococcus, Staphylococcus, or Moraxella in their airways. When their asthma was well controlled, the children had more benign bacteria in their airways such as Dolosigranulum and Corynebacterium. The switch from benign bacteria to Moraxella was linked to the highest risk of worsening asthma symptoms and has also been identified in another previous study to be linked with increased exacerbation risk.

The researchers say that more evidence is needed to identify why this correlation exists, as there may be some hidden factors that could cause a bacterial shift or worsening of asthma. There is a growing need to find a more effective treatment for asthma than ones currently in place, as such a vast proportion of the population is diagnosed with it. This study acts as a starting point for further research to continue to discover what causes differences in the severity of asthma, and if manipulating the microbiome could lead to better management or treatment.