Bacteria and bacterial DNA in atherosclerotic plaque and aneurysmal wall biopsies from patients with and without periodontitis

Background: Several studies have reported an association between chronic periodontitis (CP) and cardiovascular diseases. Detection of periodontopathogens, including red complex bacteria (RCB), in vascular lesions has suggested these bacteria to be involved in the pathogenesis of atherosclerosis and abdominal aortic aneurysms. Objective: In this study, we investigate bacteria and their DNA in vascular biopsies from patients with vascular diseases (VD; i.e. abdominal aortic aneurysms, atherosclerotic carotid, and common femoral arteries), with and without CP. Methods: DNA was extracted from vascular biopsies selected from 40 VD patients: 30 with CP and 10 without CP. The V3-V5 region of the 16S rDNA (V3-V5) was polymerase chain reaction (PCR)-amplified, and the amplicons were cloned into Escherichia coli, sequenced, and classified (GenBank and the Human Oral Microbiome database). Species-specific primers were used for the detection of Porphyromonas gingivalis. In addition, 10 randomly selected vascular biopsies from the CP group were subjected to scanning electron microscopy (SEM) for visualization of bacteria. Checkerboard DNA-DNA hybridization was performed to assess the presence of RCB in 10 randomly selected subgingival plaque samples from CP patients. Results: A higher load and mean diversity of bacteria were detected in vascular biopsies from VD patients with CP compared to those without CP. Enterobacteriaceae were frequently detected in vascular biopsies together with cultivable, commensal oral, and not-yet-cultured bacterial species. While 70% of the subgingival plaque samples from CP patients showed presence of RCB, only P. gingivalis was detected in one vascular biopsy. Bacterial cells were seen in all 10 vascular biopsies examined by SEM. Conclusions: A higher bacterial load and more diverse colonization were detected in VD lesions of CP patients as compared to patients without CP. This indicated that a multitude of bacterial species both from the gut and the oral cavity, rather than exclusively periodontopathogens, may be involved as additional risk factors in the pathogenesis of VD.