Rheumatoid arthritis and salivary biomarkers of periodontal disease

Abstract

Aim: To test the hypothesis that rheumatoid arthritis (RA) influenced levels of salivary biomarkers of periodontal disease.

Methods: Medical assessments, periodontal examinations and pain ratings were obtained from 35 RA, 35 chronic periodontitis and 35 age- and gender-matched healthy controls in a cross-sectional, case-controlled study. Unstimulated whole saliva samples were analysed for interleukin-1β (IL-1β), matrix metalloproteinase-8 (MMP-8) and tumour necrosis factor-α (TNF-α) concentrations.

Results: The arthritis and healthy groups had significantly less oral disease than the periodontitis group (P<0.0001), with the arthritis group having significantly more sites bleeding on probing (BOP) than matched controls (P=0.012). Salivary levels of MMP-8 and IL-1β were significantly elevated in the periodontal disease group (P<0.002), and IL-1β was the only biomarker with significantly higher levels in the arthritis group compared with controls (P=0.002). Arthritis patients receiving anti-TNF-α antibody therapy had significantly lower IL-1β and TNF-α levels compared with arthritis patients not on anti-TNF-α therapy (P=0.016, 0.024) and healthy controls (P<0.001, P=0.011), respectively.

Conclusion: RA patients have higher levels of periodontal inflammation than healthy controls, i.e., an increased BOP. Systemic inflammation appears to influence levels of select salivary biomarkers of periodontal disease, and anti-TNF-α antibody-based disease-modifying therapy significantly lowers salivary IL-1β and TNF-α levels in RA.

Figure 1

Box plots of salivary biomarker levels A) IL-1β, B) TNF-α, C) MMP-8 in the 3 study groups. Horizontal lines represent the 25^th, 50^th and 75^th percentiles, plus sign represents the mean, and asterisks represent outliers. RA denotes rheumatoid arthritis group. Mab_Y denotes RA patients on monoclonal anti-TNF-α antibody therapy. Mab_N denotes RA patients not receiving monoclonal anti-TNF-α antibody therapy. H denotes healthy group. P denotes periodontal disease group.

Figure 2

Scattergram and least squares line between A) MMP-8 level and %BOP, and B) MMP-8 level and %PD sites ≥5 mm by group. Group H denotes healthy, Mab_Y denotes RAon anti-TNF-α therapy, Mab_N denotes RA not on anti-TNF-α therapy, and P denotes periodontitis. In A) the slopes for the Mab_Y and P group were significant (r=0.63, P=0.02; r=0.42, P=0.01, respectively), and in B) only the slope for the P group was significant (r=0.36, P=0.04).