Correction: Microbiome Profiles in Periodontitis in Relation to Host and Disease Characteristics

Genetic Control of GCF Exudation: Innate Immunity Genes and Periodontitis Susceptibility

Chronic periodontitis is a bacterial infection associated with dentally adherent biofilm (plaque) accumulation and age-related comorbidities. The disease begins as an inflammatory exudate from gingival margins, gingival crevicular fluid (GCF) in response to biofilm lysine. After a week of experimental gingivitis (no oral hygiene), biofilm lysine concentration was linearly related to biofilm accumulation (plaque index) but to GCF as an arch-shaped double curve which separated 9 strong from 6 weak GCF responders (hosts). Host DNA was examined for single nucleotide polymorphisms (SNPs) of alleles reported in 7 periodontitis-associated genes. Across all 15 hosts, an adenine SNP (A) at IL1B-511 (rs16944), was significant for strong GCF (Fisher's exact test, p < 0.05), and a thymidine SNP (T) at IL1B+3954 (rs1143634) for weak GCF provided 2 hosts possessing IL6-1363(T), rs2069827, were included. The phenotype of IL1B+3954(T) was converted from weak to strong in one host, and of the non-T allele from strong to weak in the other (specific epistasis, Fisher's exact test, p < 0.01). Together with homozygous alternate or reference SNPs at IL10-1082 or CD14-260 in 4 hosts, all hosts were identified as strong or weak GCF responders. The GCF response is therefore a strong or weak genetic trait that indicates strong or weak innate immunity in EG and controllable or uncontrollable periodontal disease, dental implant survival and late-life comorbidities.

Metagenomic Analysis to Uncover the Subgingival and Atherosclerotic Plaque Microbiota in Patients with Coronary Artery Disease

The role of periodontal pathogens in the initiation and progression of atherosclerosis has been extensively researched, yet a precise causal mechanism has not been established. The subgingival microbiota may be a source of dissemination and may contribute to the development of atherosclerosis; hence this study attempted to characterize and compare the subgingival and atherosclerotic plaques. Plaque samples were subjected to 16S rRNA-based metagenomics to study microbiota associated with subgingival and atherosclerotic plaques collected from patients with coronary artery disease. The PCoA analysis showed that the microbiomes of subgingival plaques were highly scattered and showed a diverse microbial composition, unlike the atherosclerotic plaques that did not show evident variability in the microbial composition and formed a close distinct group. The abundance of various genera in the subgingival plaques revealed Fusobacterium (11%), Acinetobacter (13%), Veillonella (9%), and Prevotella (11%) among the top ten genera. The atherosclerotic plaques contained Acinetobacter (39%), Chryseobacterium (9%), Rhizobium (5%), and Staphylococcus (4%). All the patients examined in this study had either generalized or localized periodontitis with varying degrees of severity. The community microbiota analysis revealed that 22 bacterial genera were shared between two different plaques, with Acinetobacter being dominant. Based on the Human Oral Microbiome Database, 55% of the shared microbiota in this study have been listed as periodontal microbiota, with some of them found in increased proportions in patients with periodontitis suggesting the translocation of bacteria from the periodontal pockets into the circulation. This study provides valuable insights into the possible relationship between periodontal pathogens and atherosclerotic cardiovascular disease.

Graphical Abstract

Metagenomic Analysis of Saliva Reveals Disease-Associated Microbiotas in Patients With Periodontitis and Crohn's Disease-Associated Periodontitis

Patients with Crohn’s disease frequently develop oral health problems and show a higher prevalence of oral manifestations, such as dental caries and periodontitis, than healthy individuals do. In this study, a metagenomic analysis was carried out to characterize the salivary microbiota in patients with either periodontitis or Crohn’s disease-associated periodontitis. Saliva samples were collected from six patients with both Crohn’s disease and periodontitis (Cm group), six patients with periodontitis alone (Pm group), and six healthy individuals (Hm group). Genomic DNA was collected from these samples for high-throughput Illumina HiSeq metagenomic sequencing. The composition of the bacterial communities and their metabolic pathways and gene functions were characterized and compared among the three study groups. The salivary microbial communities were significantly different among the three groups, with Firmicutes, Actinobacteria, and Bacteroidetes showing the most significant differences. The Cm and Pm groups had higher abundances of Bacteroides fragilis, Prevotella baroniae, Prevotella enoeca, and Prevotella dentasini than the Hm group. The Cm and Pm groups also showed differences in their salivary microbial communities, in that the Cm group had relatively high abundances of Firmicutes and Proteobacteria, whereas the Pm group had relatively high abundances of Actinobacteria, Bacteroidetes, and Fusobacteria. In total, 34 Pm-associated (e.g., Fusobacteria and Corynebacterium matruchotii), 18 Cm-associated (e.g., Capnocytophaga and Streptococcus oralis), and 18 Hm-associated (e.g., Streptococcus and Bacillales) predominant microbial species were identified. Most genes were involved in carbohydrate and amino acid metabolism, with those of the Cm and Pm groups showing more similarity to one another but significant differences from those of the Hm group. Most of the antibiotic resistance genes were found in the Pm group. In conclusion, the salivary microbial community structure and abundance were distinct among patients with Crohn’s disease-associated periodontitis, patients with periodontitis, and healthy individuals. Further studies are needed to evaluate the potential value of these microbiota and microbiome differences in the clinical diagnosis and treatment of oral diseases.