The subgingival microbiome of clinically healthy current and never smokers

Abstract

Dysbiotic oral bacterial communities have a critical role in the etiology and progression of periodontal diseases. The goal of this study was to investigate the extent to which smoking increases risk for disease by influencing the composition of the subgingival microbiome in states of clinical health. Subgingival plaque samples were collected from 200 systemically and periodontally healthy smokers and nonsmokers. 16S pyrotag sequencing was preformed generating 1,623,713 classifiable sequences, which were compared with a curated version of the Greengenes database using the quantitative insights into microbial ecology pipeline. The subgingival microbial profiles of smokers and never-smokers were different at all taxonomic levels, and principal coordinate analysis revealed distinct clustering of the microbial communities based on smoking status. Smokers demonstrated a highly diverse, pathogen-rich, commensal-poor, anaerobic microbiome that is more closely aligned with a disease-associated community in clinically healthy individuals, suggesting that it creates an at-risk-for-harm environment that is primed for a future ecological catastrophe.

Figure 1

PCoA plots of the UniFrac distance for all samples by smoking status. (a) All 200 samples, a subset of (b) 50 Caucasians and (c) 34 African Americans are shown. All samples demonstrated significant clustering based on tobacco exposure, irrespective of ethnic background (P<0.05, analysis of similarity (ANOSIM) on unweighted UniFrac distances). (d) A subset of 17 African-American and 25 Caucasian smokers that does not demonstrate significant clustering based on tobacco exposure.

Figure 2

(a) Phylogenetic tree of the 572 s-OTUs. It was generated using the interactive tree of life web application (http://itol.embl.de/). The outermost circle indicates the normalized mean relative abundances of the s-OTUs in nonsmokers (green) and smokers (red). Overall abundances for each OTU are indicated by the black-to-gray circular gradient (middle circle). The Gram staining and oxygen requirement characteristics are represented by the innermost circle with Gram-negative aerobes (red), Gram-negative anaerobes (magenta), Gram-positive aerobes (blue), Gram-positive anaerobes (purple) and unknown characteristics (gray). (b, c) The relative abundance of selected species in current smokers and nonsmokers. PCoA plots of the UniFrac distances are shown, with the size of each bubble representing the abundance of the species in that sample.