What is already known
The microbiota of the upper airways can influence a person’s susceptibility to acute infections and long-term conditions such as asthma. However, while most studies have focused on the upper respiratory tract microbiota in infants, little is known about how this microbiota evolves throughout life and impacts overall health.
What this research adds
Researchers examined the upper airways microbiota of 3,160 healthy Dutch people aged zero to 80 years old. A person’s nasal microbiota is more similar to their own throat microbiota than to the throat microbiota of others. While the nasal microbiota continues to evolve into early adulthood, the throat microbiota reaches full development during childhood. The nasal microbiota is influenced by age, sex and respiratory infections, whereas the throat microbiota is shaped by lifestyle factors such as smoking and antibiotic use.
Conclusions
The findings suggest that the development and maturation of the nasal microbiota are influenced by age and sex, while lifestyle factors shape the throat microbiota.
The microbiota of the upper airways can influence a person’s susceptibility to acute infections and long-term conditions such as asthma. Now, researchers have mapped the upper airway microbiota of healthy individuals, shedding light on its role in respiratory health and disease.
The findings, published in Cell, suggest that the development and maturation of the nasal microbiota are influenced by age and sex, while lifestyle factors shape the throat microbiota.
Because the upper respiratory tract acts as a barrier to pathogens and interacts with the immune system, the microbes residing in the nose and throat have been linked to many respiratory conditions. However, most studies have focused on the upper respiratory tract microbiota in infants; little is known about how this microbiota evolves throughout life and impacts overall health.
To characterize the changes of the upper respiratory tract microbiota across the lifespan, Mari-Lee Odendaal at Utrecht University in the Netherlands and her colleagues examined 5,500 samples from the nasal and oral cavities of 3,160 healthy Dutch people aged zero to 80 years old.
Microbiota maturation
The researchers found that the microbiota of the upper airways, particularly in the nose and throat, changes as people age. However, different areas have unique microbiota patterns. For example, the noses and throats of younger people have more bacteria overall but less variety among them. In contrast, older individuals have a more diverse range of bacteria in their noses and throats but a lower number of bacteria.
The amounts of bacteria such as Dolosigranulum pigrum and Corynebacterium species also change with age, with D. pigrum being more abundant in younger people. The abundance of this microbe has been linked to the absence of disease and the inhibition of potential pathogens.
A person’s nasal microbiota is more similar to their own throat microbiota than to the throat microbiota of others, the researchers also found. While the nasal microbiota continues to evolve into early adulthood, the throat microbiota reaches full development during childhood.
Knowledge gap
The team found sex differences in the nasal microbiota, with bacteria such as Lawsonella clevelandensis, Finegoldia magna and Peptoniphilus species being more abundant in males than females. These differences emerge during puberty, likely due to hormonal changes, the authors say.
Further analyses showed that the airway microbiota is altered in people who have recently had mild respiratory infection symptoms. More severe symptoms cause greater changes in the nasal microbiota. In contrast with the nasal microbiota, the throat microbiota is shaped by lifestyle factors such as smoking and antibiotic use, the researchers found.
“We shed light on age-related dynamics of the [upper respiratory tract] microbiota in a general population, filling a knowledge gap that has persisted despite numerous investigations of the human microbiome,” the authors say.
