Salivary interleukin 6, interleukin 8, interleukin 17A, and tumour necrosis factor α levels in patients with periodontitis and rheumatoid arthritis

Introduction
Rheumatoid arthritis (RA) and periodontitis share risk factors and inflammatory pathways that could be related to cytokines, such as interleukin (IL)-6, IL-8, IL-17A, and tumour necrosis factor-α (TNF-α). The aim of this study was to compare periodontal status and salivary levels of selected cytokines between patients diagnosed with RA and periodontitis. RA patients were assessed for the potential influence of anti-rheumatic therapy.

Material and methods
One hundred and six patients were enrolled in a cross-sectional study. Medical assessment and periodontal examination were performed in 35 patients with chronic periodontitis, in 35 patients with RA and chronic periodontitis, and in 36 controls. Unstimulated whole saliva samples were analysed for IL-6, IL-8, IL-17A, and TNF-α.

Results
Significant differences in biomarkers and periodontal parameters were found among groups. Study groups exhibited higher mean pocket depth (PD), number of PD > 4 mm, and mean clinical attachment loss, when compared with controls. The RA group had lower bleeding on probing index and PD, but higher values of plaque indices than the periodontitis group. Concentration of evaluated cytokines were higher in the RA and periodontitis groups, compared with controls. The periodontitis group showed also higher levels of IL-6, IL-17A, and TNF-α in comparison to RA. RA patients were treated with disease-modifying anti-rheumatic drugs (DMARDs) and glucocorticosteroids.

Conclusions
Salivary levels of IL-6, IL-8, IL-17A, and TNF-α can be affected by periodontitis, RA, and presumably DMARDs. DMARD therapy appears to reduce destructive and inflammatory processes in periodontal tissues because lower values of PD, BOP, and salivary levels of IL-6, IL-17A, and TNF-α were found in RA.