Secrets of the nasal flora
It seems logical that the respiratory microbiota should be implicated in a respiratory disease such as asthma... but this still requires proof! Some studies of the nasal microbiota are working to show its influence on the development of asthma and have just added a piece to the jigsaw.
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While the microbiota of the lower respiratory tract (bronchi and lungs) has already been linked to the development of asthma9, the nasal microbiota has been little investigated from this perspective up until now. To remedy this, a team of American researchers focused on this topic. Their aim was to identify the composition of the nasal microbiota of asthma patients and compare it with that of healthy individuals in order to identify signs of its role in the disease. Samples were taken from the nasopharynx (at the end of the nasal cavity) over a one-year period, from individuals aged between 10 to 73 years old, some of whom presented with asthma exacerbation, other with a stable form, and finally others who were healthy controls10.
The initial hypothesis was confirmed: the nasal microbiota of each group had significantly different compositions. Asthmatic individuals has a microbiota richer in two families of bacteria (Bacteroidetes and Proteobacteria) compared to the control group. Four species were generally observed to a greater extent in asthmatic individuals: some already associated with localized inflammatory diseases (but never with asthma), others already reported in other respiratory disorders; finally others better known for their role in vaginosis. The microbes detected also differed depending on whether the form of the disease was exacerbated or stable.
Biomarkers within reach of a swab
This study is one of the largest conducted to date on the correlation between the nasal microbiota and asthma. Its results–to be consolidated by future analyses–represent an important step forward for research and are consistent with data collected for the lower airway study. On this basis it may be suggested that nasal microbiota, samples of which can be obtained much more easily and less invasively than by an internal bronchial examination (bronchoscopy), can be used to understand the role of the respiratory microbiota in the pathogenesis of asthma and its course. The bacteria identified could be subject to more detailed analysis to clarify their respective roles and be considered a simple tool to detect and monitor asthma. These are numerous avenues to be explored in the future from a scientific perspective.
9. Gilstrap DL, Kraft M. Asthma and the host-microbe interaction. Journal of Allergy and Clinical Immunology 2013
10. Fazlollahi M, Lee TD, Andrade J et al. The Nasal Microbiome in Asthma. Journal of Allergy and Clinical Immunology (2018)