Association Between Circulating Tumor Necrosis Factor Receptors and Oral Bacterium in Patients Receiving Hemodialysis: a Cross-Sectional Study

High levels of tumor necrosis factor (TNF) receptors (TNFRs; TNFR1 and TNFR2), markers of inflammation, have been reported as significant predictors of mortality in hemodialysis patients. Porphyromonas gingivalis is a major pathogenic bacterium involved in periodontitis, which induces systemic inflammation. We investigated the association between the abundance of P. gingivalis in saliva and serum TNFR levels in hemodialysis patients. A cross-sectional study was conducted on 121 hemodialysis patients visiting a clinic in the Tokyo metropolitan area. Medical interviews and examinations, comprehensive dental examinations, bacterial examinations for P. gingivalis in saliva, and measurements of circulating TNFR levels were conducted. Multiple linear regression analysis was performed to evaluate the association between the number of P. gingivalis and circulating TNFR levels. TNFR1 and TNFR2 were positively correlated with high-sensitivity C-reactive protein (hsCRP). Severe periodontitis was significantly associated with the number of P. gingivalis in saliva but not serum TNFR levels. The number of P. gingivalis was significantly associated with both TNFR1 and TNFR2 levels in sera after adjusting for age, sex, body mass index, smoking status, history of diabetes, prior cardiovascular disease events, serum levels of hsCRP and albumin, and severity of periodontitis [for TNFR1: coefficient 0.76, 95% confidence interval (CI) 0.14–1.37, p = 0.02; for TNFR2: coefficient 0.95, 95% CI 0.09–1.80, p = 0.03]. Circulating TNFR levels are associated with the number of P. gingivalis in saliva after adjusting for relevant clinical factors.