Nasal microbiota in infancy: dynamic but personalized

Published Online: January 29, 2015

The immune system matures in early life and this may depend, among other factors, on the development of an individual’s microbiome—i.e. the collection of microorganisms that live throughout our bodies. Thus, a healthy, “correct” colonization of our bodies by various microorganisms may trigger the appropriate development of the immune system, while potential infectious agents, or pathogens, can lead to certain diseases. Because the dynamics of healthy upper respiratory systems in early life is largely unknown, Mika and colleagues have investigated the nasal microbiota in the first year of life within a prospective cohort study. Their results were recently published in The Journal of Allergy and Clinical Immunology (JACI).

The authors of this study recruited infants from Switzerland, a sampling area where most residents are relatively similar. The included infants’ dates of birth were equally distributed throughout the year and all infants were breastfed. For this study, mothers of infants took nasal swabs every two weeks, and the infants’ state of health—including respiratory infections and vaccination history—was documented during their first year of life. After removing low quality samples, the microbiota of more than 800 nasal swabs from 47 infants was analyzed. This analysis was done using previously validated 16S rRNA next-generation sequencing (i.e. the 454 Roche sequencing platform).

With this design, the authors were able to demonstrate that age and seasonal variability needs to be taken into account when assessing nasal microbiota data within the first year of life. Strikingly, and for the first time, the authors revealed that within individual infants the microbiota remained relatively similar week to week, as compared to changes seen in other infants—indicating a personalized microbiota, i.e. a microbiota unique to each person.  

Interestingly, this relative uniqueness of an individual’s microbiota was found to be most pronounced in the winter months while in the summer months the composition of an individual’s microbiota changed much more often. As for age, similarly, the microbiota was found to be less stable and ‘skin-alike’ in the first three months, and to develop to a ‘characteristic’ healthy upper respiratory tract microbiota thereafter.

The fact that this study found a personalized microbiota is crucial as it serves as a baseline for future intervention studies. However, the microbiota is also highly dynamic and this study does not answer all the questions related to this issue. This may be due to technical challenges, a relatively small sample size, and not yet analyzed, additional epidemiological factors influencing the composition of the microbiota. Microbiota studies are still relatively rare, but are part of a new and exciting research area. Much more information is expected emerge from future studies.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

Close-up of pine tree branches in Winter Close-up of pine tree branches in Winter