Correlation of Toll-like receptor 4, interleukin-18, transaminases, and uric acid in patients with chronic periodontitis and healthy adults.

BACKGROUND Because of the potential association between periodontal disease and inflammation, the purpose of the present study is to examine the level of Toll-like receptor 4 (TLR-4), interleukin-18 (IL-18), and uric acid as markers of the inflammatory host response in the plasma and saliva of healthy individuals and patients with periodontitis. In addition, routine biochemical parameters such as fasting glucose, insulin, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, alanine transaminase (ALT), and aspartate transaminase (AST) were measured. The authors also wanted to check whether patients with chronic periodontitis (CP) exhibit different modulations in salivary and/or plasma concentrations of these parameters compared with clinically healthy individuals. METHODS Saliva and plasma samples were collected from 40 patients with CP and 20 healthy individuals. TLR-4 and IL-18 measurements were done using commercially available enzyme-linked immunosorbent assay kits. Total, HDL, and LDL cholesterol; triglycerides; fasting glucose; AST; and ALT levels were analyzed on a biochemistry analysis system using specific kits. Non-parametric tests were used for certain parameters in the statistical analyses because the data did not follow Gaussian distribution. RESULTS Significant differences were observed in plasma and salivary TLR-4 and IL-18 levels, along with clinical measurements such as plaque index and probing depth, in patients with CP (P < 0.001). The plasma level of TLR-4 was found to be increased from 0.99 to 3.28 ng/mL in patients with CP. Salivary TLR-4 levels also showed a slightly higher increase in the diseased state (12.44 to 29.97 ng/mL). A significant increase of ≈ 46% was recorded in the plasma IL-18 level. However, salivary IL-18 levels rose up to > 5-fold in the patients with CP compared with healthy individuals. The level of plasma uric acid was found to be highly significantly increased compared with control individuals. HDL cholesterol and triglyceride also showed significant differences (P < 0.02 and P < 0.03, respectively). Plasma glucose, total cholesterol, LDL cholesterol, and insulin levels did not show any significant difference. There was only a slight increase in plasma AST and ALT levels between diseased and healthy states (22.55 versus 25.50 IU/L and 12.35 versus 15.95 IU/L, respectively). However, salivary AST and ALT levels showed a ≈ 6-fold rise in the patients with CP compared with the healthy individuals. Cross-correlation analysis in the periodontitis disease group showed a significant association of plasma AST, salivary AST, and salivary ALT with uric acid level. CONCLUSIONS Based on this study, the authors believe that TLR-4, IL-18, and uric acid could have a role in the inflammatory pathology of periodontitis. These parameters are suggested to be useful in the prognosis and diagnosis of CP. However, the mechanistic association of these parameters with inflammatory pathology of patients with periodontitis needs to be further elucidated in a higher number of samples.