Periodontal disease and the oral microbiota in new-onset rheumatoid arthritis

Abstract

Objective: To profile the abundance and diversity of subgingival oral microbiota in patients with never-treated, new-onset rheumatoid arthritis (RA).

Methods: Periodontal disease (PD) status, clinical activity, and sociodemographic factors were determined in patients with new-onset RA, patients with chronic RA, and healthy subjects. Multiplexed-454 pyrosequencing was used to compare the composition of subgingival microbiota and establish correlations between the presence/abundance of bacteria and disease phenotypes. Anti-Porphyromonas gingivalis antibody testing was performed to assess prior exposure to the bacterial pathogen P gingivalis.

Results: The more advanced forms of periodontitis were already present at disease onset in patients with new-onset RA. The subgingival microbiota observed in patients with new-onset RA was distinct from that found in healthy controls. In most cases, however, these microbial differences could be attributed to the severity of PD and were not inherent to RA. The presence and abundance of P gingivalis were also directly associated with the severity of PD and were not unique to RA. The presence of P gingivalis was not correlated with anti-citrullinated protein antibody (ACPA) titers. Overall exposure to P gingivalis was similar between patients with new-onset RA and controls, observed in 78% of patients and 83% of controls. The presence and abundance of Anaeroglobus geminatus correlated with the presence of ACPAs/rheumatoid factor. Prevotella and Leptotrichia species were the only characteristic taxa observed in patients with new-onset RA irrespective of PD status.

Conclusion: Patients with new-onset RA exhibited a high prevalence of PD at disease onset, despite their young age and paucity of smoking history. The subgingival microbiota profile in patients with new-onset RA was similar to that in patients with chronic RA and healthy subjects whose PD was of comparable severity. Although colonization with P gingivalis correlated with the severity of PD, overall exposure to P gingivalis was similar among the groups. The role of A geminatus and Prevotella/Leptotrichia species in this process merits further study.

Trial registration: ClinicalTrials.gov NCT01198509.

Figure 1

Clustering of species-level operational taxonomic units (OTU) among groups studied. Bar graphs show relative abundance of oral microbiota (phylum level) among (A) NORA, CRA and healthy controls and (B) participants with No PD vs PD. Clustering by Yue and Clayton analysis comparing (C) patients with new-onset rheumatoid arthritis (NORA) vs patients with chronic rheumatoid arthritis (CRA) vs healthy control participants, and (D) participants with healthy gingiva or gingivitis (No PD) vs those with slight, moderate or severe periodontal disease (PD).

Figure 2

Abundance of periodontopathic bacteria (OTU-level) in patients with new-onset rheumatoid arthritis (NORA) and chronic rheumatoid arthritis (CRA). Species associated with periodontal disease, such as (A) Tannerella forsythia and (B) Treponema medium, are significantly more abundant in NORA patients compared to CRA. (C) No significant differences (NS) are observed for Porphyromonas gingivalis.

Figure 3

Prevalence and abundance of Porphyromonas and P. gingivalis (OTU1) in 83 study participants, grouped by rheumatoid arthritis (RA) status [healthy controls (HC), new-onset RA (NORA), chronic RA (CRA)] and periodontal disease (PD) status [healthy gingiva or gingivitis (No PD); slight (SLT), moderate (MOD), and severe (SEV) PD]. Although the genus Porphyromonas (A, C) is present almost universally and irrespective of RA or PD status, P. gingivalis (B, D) is significantly associated with moderate and severe PD, and not with presence of RA. (A, B) Each square represents a single individual. The darker the intensity of the box, the greater the relative abundance of Porphyromonas or P. gingivalis. NS = not significant.

Figure 4

Anti-HtpG peptide antibody (anti-P18γ) serum levels and overall P. gingivalis exposure among different groups. (A) Anti-P18γ antibodies were found in 72% of healthy subjects, 63.3% of NORA patients, and 50% of CRA patients (p=0.18; ANOVA); mean levels were not significantly different. (B) Prevalence of P. gingivalis in oral microbiota (16s) and anti-P18γ antibody (serology) in all 83 participants, grouped by healthy controls (Healthy) and RA status (NORA and CRA). Red squares denote presence of P. gingivalis by 16S pyrosequencing and/or detectable anti-P. gingivalis antibody. Each square represents a single individual and contiguous squares are representative of same participant. (*) Serum not available in one NORA participant. HC=Healthy controls; NORA=New-onset Rheumatoid arthritis; CRA=Chronic RA; PD=Periodontal disease; No-PD=Healthy gingiva.