Comparison between upper and lower airway microbiome profiles in chronic rhinosinusitis patients.

BACKGROUND: Dysregulation of the airway microbiota is thought to contribute to airway inflammation in both chronic rhinosinusitis (CRS) and asthma. However, the relationship between the upper and lower airway microbiome remains unclear.

METHODS: Sinus and lung brushes were collected from 29 CRS participants undergoing sinus surgery. DNA was extracted and submitted for 16s rRNA microbiome sequencing. Alpha and beta diversity metrics, taxonomic composition, and differences between individual taxa were compared for paired sinus and bronchial samples.

RESULTS: Twenty-three out of 29 participants had sufficient samples for analysis. The mean (standard deviation) age was 51.59 (14.57) years, and 10 (44%) patients were female. Twelve (52%) patients had comorbid asthma. Sinus brushes had significantly higher alpha diversity indexes (Shannon and Faith) compared to bronchial brushes (p < 0.001). Beta diversity metrics were significantly different between the sinus and bronchial samples. Principal coordinate analysis showed no clustering of paired nasal and bronchial samples. Sinus brushes had significantly more Lawsonella, Corynebacterium, and Staphylococcus compared to bronchia brushes, while the latter were enriched in Tropheryma and Sphingomonas, among others (false discovery rate [FDR]-adjusted p < 0.01). Finally, CRS patients with comorbid asthma had significantly higher Pseudomonas and Peptoniphilus in sinus brushes and lower Prevotella in bronchial brushes when compared to non-asthmatics (FDR-adjusted p < 0.01).

CONCLUSION: The sinus and bronchial bacterial microbiomes differ in important ways. Our study suggests that migration of bacteria from the sinus into the lower airways is unlikely in patients with CRS.