Chest
Translating Basic Research into Clinical PracticeThe Airway Microbiome and Disease
Section snippets
The Airway Microbiome in Health and Disease
The origin of the airway microbiome is yet to be delineated. Endogenous flora from the intestines and the oropharynx, and/or environmental microbes could provide the initial seeding source, or, most likely, a continued source of bacteria (Fig 1). A study by Charlson et al7 suggested that the bacterial species detected in the lower respiratory tract of healthy individuals likely originated from microaspiration and reflected the microbiome detected in the upper respiratory tract. Certainly, it is
A Functional Role for the Airway Microbiome?
In spite of a growing bulk of literature describing the airway microbiome in different disease settings, the evidence for its function is still limited. Studies using axenic (germ-free) mice have the potential to address these questions, since these mice are completely sterile. Thus, in theory, future studies could selectively reconstitute the intestinal or airway microbiome and dissect their relative roles.
Some of the first studies to address the importance of the microbiota in allergic airway
What Can We Learn From Other Tissues?
There is a wealth of information available describing host-microbe interactions in the intestine. As mentioned earlier, species diversity is clearly linked to health, while limited diversity is associated with IBD.11, 12 Moreover, certain bacterial species have been linked with the differentiation of inflammatory or regulatory T cells in the intestine.24 Thus, placing the respiratory literature into the context of what is known for the intestine, there already are many parallels. This does
Implications for Clinical Practice
As the outgrowth of certain bacteria is associated with disease severity in CF and COPD,5, 9, 10, 13 this could be used as an indicator for timely clinical intervention and successful disease management. Moreover, the presence of specific bacterial markers such as nucleic acids, proteins, or metabolites could be more sensitive than routine diagnostics and may also precede clinical manifestation of disease. But the ultimate goal would encompass harnessing the understanding of the microbial
Conclusion
On the basis of multiple studies from different international laboratories, the existence of the airway microbiome is now firmly established. Clearly, the field is still in its infancy, and key questions remain to be answered—most notably, what is its function and how can we use it to prevent or treat chronic lung diseases? Is a “pathogenic” microbiome the basis for exacerbations of asthma and COPD? Does it provide the seed for secondary infections? Is there a link between the intestinal
Acknowledgments
Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
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