The human laryngeal microbiome: effects of cigarette smoke and reflux

Abstract

Prolonged diffuse laryngeal inflammation from smoking and/or reflux is commonly diagnosed as chronic laryngitis and treated empirically with expensive drugs that have not proven effective. Shifts in microbiota have been associated with many inflammatory diseases, though little is known about how resident microbes may contribute to chronic laryngitis. We sought to characterize the core microbiota of disease-free human laryngeal tissue and to investigate shifts in microbial community membership associated with exposure to cigarette smoke and reflux. Using 454 pyrosequencing of the 16S rRNA gene, we compared bacterial communities of laryngeal tissue biopsies collected from 97 non-treatment-seeking volunteers based on reflux and smoking status. The core community was characterized by a highly abundant OTU within the family Comamonadaceae found in all laryngeal tissues. Smokers demonstrated less microbial diversity than nonsmokers, with differences in relative abundances of OTUs classified as Streptococcus, unclassified Comamonadaceae, Cloacibacterium, and Helicobacter. Reflux status did not affect microbial diversity nor community structure nor composition. Comparison of healthy laryngeal microbial communities to benign vocal fold disease samples revealed greater abundance of Streptococcus in benign vocal fold disease suggesting that mucosal dominance by Streptococcus may be a factor in disease etiology.

Figure 1

Relative abundance (%) of common genera (A) and KEGG Ortholog (B) across 97 participants.

Figure 2. Comparison of bacterial community structure of false vocal fold biopsies.

Nonmetric multidimensional scaling (nMDS) plot of the Bray-Curtis diversity index calculated from square root transformed OTU table. Lowest stress: 0.159. Smokers (Normal, LPR, GERD); Nonsmokers (Normal, LPR, GERD).

Figure 3. Comparison of bacterial community structure of false vocal fold biopsies and vocal fold lesions.

Nonmetric multidimensional scaling (nMDS) plot of the Bray-Curtis diversity index calculated from square root transformed OTU table. Lowest stress: 0.159. False Vocal Fold Biopsies; Vocal Fold Lesions (Reinke’s edema, cyst, nodule, polyp).

Figure 4. Relative abundance of common genera across all false vocal fold biopsies and vocal fold lesions.

Figure 5. Relative abundance of top genera found in false vocal fold biopsies and vocal fold lesions.

Error bars represent 95% confidence intervals.

Figure 6. Schematic outlining common microbes across the aerodigestive tract,,,.