Associations Between Obesity, Periodontitis, and Salivary Cytokine Levels

Objectives: Obesity is associated with periodontitis. Systemic low-grade inflammation related to obesity has been presented as one explanatory factor in this association. Our aim was to examine whether there is a relationship between obesity, periodontitis, and levels of salivary inflammatory cytokines.
Methods: Salivary cytokine concentrations were measured from 287 non-diabetic obese (BMI >35kg/m²) subjects and 293 normal weight controls (BMI 18.5-25kg/m²) with Luminex xMAP technique. Their periodontal status was defined according to a cumulative risk score (CRS) index, which was previously validated in two independent study populations (Gursoy et al. Dis Markers 2011; Salminen et al. J Clin Periodontol 2014). CRS index takes into account salivary Porphyromonas gingivalis, interleukin (IL)-1β and matrix metalloproteinase-8 concentrations to calculate the risk of having periodontitis (CRS I, low risk; CRS II, medium risk; CRS III, high risk). Cytokine levels between study groups were compared with Kruskall Wallis test and with Mann Whitney U test.
Results: Increased CRS index (p=0.015) and IL-8 concentrations (p=0.033) and decreased IL-10 concentrations (p=0.022) were detected in obese subjects compared with non-obese subjects. IL-1-receptor antagonist (IL-1Ra) and IL-8 levels were higher, while IL-10 and tumor necrosis factor (TNF)-α levels were lower in the CRS II (p<0.001) and CRS III (p<0.001) groups than in the CRS I group. When the adjusted associations of CRS index with obesity and salivary cytokines were calculated, CRS III associated with salivary IL-1Ra, IL-8, and IL-10 concentrations. The association observed between obesity and CRS was lost after salivary IL-1Ra, IL-6, IL-8, IL-10, and TNF-α were included in the analyses.
Conclusions: This study indicates that four salivary cytokines explained the observed association between obesity and periodontitis. Further research is needed to explore whether local or/and systemic low-grade inflammation explains the association between obesity and periodontitis.