Research provides valuable insights into the human nasal microbiome, revealing sex-specific differences and offering potential new avenues for developing treatments against respiratory diseases.

A research team led by BGI-Research has created the most extensive catalog of the human nasal microbiome to date, using large-scale metagenomic high-throughput deep sequencing. This new study, which has been published in Genome Biology, represents the first systematic effort to map the nasal microbial ecosystem and evaluate this critical barrier's resilience against respiratory pathogens.

The study “Integrated large-scale metagenome assembly and multi-kingdom network analyses identify sex differences in the human nasal microbiome” was published in Genome Biology.

The human nasal cavity, which encounters the external environment more directly than most other parts of the respiratory tract, is home to millions of microbiotas. These bacteria, fungi, and other microbes form a complex, stable community, co-evolving with the human body to create a mutually beneficial relationship. This "united front" helps protect the body from harmful pathogens.

The study offers a more holistic perspective on the human nasal microbiome, which has been relatively understudied. By examining nasal samples from 1,593 healthy young adults, the research team successfully reconstructed 4,197 metagenome-assembled bacterial genomes, including 82 newly discovered species, and cataloged 131 fungal species. This achievement represents the most complete reference blueprint of the nasal microbiome to date.

One of the key findings of the study is the discovery of significant sex-specific differences in the nasal microbiome. Using a newly developed microbial network analysis algorithm, the researchers identified keystone microbial species - those that play a pivotal role in maintaining microbiome stability. Thirteen keystone taxa were identified in males and ten in females, with the female nasal microbiome displaying higher stability and antagonistic potential against pathogens. This may help explain why men are often more susceptible to respiratory diseases than women.

Additionally, the study found the keystone microbial species appear to have evolved under long-term purifying selection, suggesting that evolutionary pressures may have influenced these differences.

Overall representation of the microbes in anterior nares of healthy young adults.

By utilizing their novel network analysis approach, the team was able to assess the significance of individual species within the microbiome and capture their intricate interactions. This method could be a powerful tool for future research, particularly in identifying microbial species with the greatest potential to influence overall nasal microbiome health.

The study offers a valuable resource for scientists investigating the nasal microbiome in relation to respiratory diseases and opens up new possibilities for developing treatments, such as innovative antibiotics or probiotic nasal sprays that could enhance the body's natural defenses by strengthening the nasal microbiome. 

"Our findings enhance the understanding of the nasal microbiome and offer new clues for developing preventive and therapeutic strategies," said Dr. Ruijin Guo, the correspondent author of the study and an associate researcher at BGI-Research. "In the future, we can precisely boost these ‘keystone’ bacteria, for example, by using nasal sprays containing functional probiotics to strengthen the nasal microbiome, making it more robust and more effective in preventing respiratory diseases."

Ethical review approval was obtained for this study.

The study can be accessed here: https://genomebiology.biomedcentral.com/articles/10.1186/s13059-024-03389-2