Oral Microbiome Analysis of Aortic and Femoral Arteries

Objectives: An association between bacteria and atherosclerosis has been postulated. Our objective was to identify oral bacterial species in non-atherosclerotic aortic and femoral artery tissue from patients who underwent coronary or femoral artery bypass surgery, using a targeted metagenomics approach to screen for nearly 600 oral bacterial species.
Methods: Tissue specimens from 27 male patients [mean age (SD), 62.5 (9.9) years] were harvested from clinically non-atherosclerotic areas of aortic (n=19) and femoral (n=8) artery vessels used for attachment of bypass grafts. Bacterial DNA was extracted and used for analysis by HOMINGS (Human Oral Microbe Identification using Next Generation Sequencing) based on sequencing of the V3-V4 hypervariable region of 16S rRNA gene. ProbeSeq program was used for in silico bacterial species identification. Sequence reads that were uniquely matched to a bacterial species were counted as “hits” and used for statistical analyses.

Results: A total of 202 unique bacterial species were detected in aggregate in our patient cohort. Porphyromonas gingivalis [mean hits (SD), 32,774 (28,361)] and Escherichia genus [mean hits (SD), 11,900 (19,435)] were the most predominant taxa detected compared to all other taxa [mean hits (SD), 420 (1,988)]. These two taxa had similar hits per patient distributions in both aortic and femoral artery tissues across patients. In addition, P. gingivalis hits per patient positively correlated with systolic (r=0.42, p=0.031) and diastolic blood pressure (r=0.55, p=0.003), consistent with reported role of P. gingivalis in hypertensive disorders. Finally, 22% of patients had over 50% unmatched sequence reads, suggesting a significant presence of unknown oral or non-oral bacterial species.

Conclusions: This is the first study using targeted metagenomics to screen for all known oral bacterial species in healthy artery tissues of patients with atheroscherosis. The oral microbiome might constitute a source for arterial wall colonization by pathogenic commensals potentially involved in the development of atherosclerotic cardiovascular disease.