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17 - 01 - 2017

Asthma and pulmonary bacteria: explanations by Muriel Thomas

INRA researchers have shown for the first time that lung bacteria can exaggerate or alleviate the symptoms of asthma. Muriel Thomas, research director and co-author of the study, tells us more about this major discovery.


Research carried out by researchers from the INRA and the University of Ghent (Belgium), published in the ISME Journal on the 3rd of January 2017, show that bacteria present in the lungs can alleviate certain respiratory pathologies such as asthma, or, on the contrary, exacerbate them. Muriel Thomas, Director of the joint research unit Food and Gut Microbiology for human Health and co-author of this study tells us more on the topic.



What is the microbiota? When was the pulmonary microbiota discovered and how was it revealed?


“The microbiota is a collection of microorganisms. The human microbiota is mostly made of bacteria but there may be other microorganisms such as yeast or viruses. Early publications on the pulmonary microbiota date back to 2010.

We knew that bacteria could be present in the lungs, tuberculosis for example is caused by bacteria, but this phenomenon was associated with pathologies. What is new is to suggest that there is a community of microorganisms in the lungs that is not associated to disease and may even help to fight certain diseases.” 


Could you describe the different stages of this work linking the pulmonary microbiota and asthma, especially at the experimental level? What results did you get?


“Everything was carried out via mouse studies, there is no human component. It was mostly fundamental research with a targeted application.

We first collected the bacteria present on the lungs of mice at different stages after birth. The same was done with mice who had inhaled a respiratory allergen in order to develop allergic-linked asthma.

We observed that the mice that developed asthma had a very high number of bacteria, particularly staphylococci. We assumed that these bacteria had a deleterious and aggravating effect on the disease.

We also found that the lungs were able to react differently depending on the bacteria and could select for bacteria with a potentially moderate effect on asthma.

We then repeated tests on asthma in mice in the presence of one or other of these bacteria. Result: the animals that inhaled the deleterious bacteria were sicker than others and the animals that inhaled the supposedly protective bacteria had an attenuated form of asthma.”


“We deduced that the bacteria that live in the lungs vary according to respiratory health and hay have a role in the susceptibility to asthma.”


Would you have been able to achieve these same results without using an animal model?


“We could not have achieved these results without an animal model, since we had to get bacteria in situ, that is, bacteria living in the deep areas if the lungs. This couldn’t have been possible using cell cultures or in humans. Moreover, we able to study the lungs of mice at different stages of their life.”


What are the next steps? What can this fundament study lead to?


“From this point onwards, we will try to conduct this type of research looking at other pulmonary pathologies, to better understand the mechanisms of action, to find other bacteria of interest for other respiratory pathologies, and to know whether the intestinal microbiota can also have an impact, since all microbiota communicate with each other.


Just like for the intestinal microbiota, this research could lead to therapeutic applications such as oral or inhaled probiotics that would act on the pulmonary microbiota and the intensity of asthma.”


Interview by Hélène Bour


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