Inflammatory cytokines in saliva: early signs of metabolic disorders in chronic kidney disease. A controlled cross-sectional study.

OBJECTIVE: The aim of this study was to evaluate correlations between levels of cytokines in secreted stimulated saliva in patients with chronic kidney disease (CKD) and hyposalivation. STUDY
DESIGN: Seventy patients with clearance <20 mL/min/1.73 m(2) were evaluated; 40 were predialysis, 21 hemodialysis, and 9 peritoneal dialysis, and they were matched with 70 control subjects. Salivary flow rate was measured and submandibular/sublingual saliva collected. Analyses were performed for whole protein content using a protein assay, and levels of tumor necrosis factor (TNF) α, interleukin (IL) 1β, γ-interferon (γ-INF), IL-6, IL-8, IL-10, monocyte chemotactic protein (MCP) 1, and soluble intercellular adhesion molecule (sICAM) 1, by using Luminex technology.
RESULTS: Patients with CKD had lower (P = .03) stimulated salivary secretion rate and higher salivary whole protein concentration (P = .002) than control subjects. Concentrations of IL-8 (P = .03) and MCP-1 (P = .002) were decreased and TNF-α/IL-10 (P = .05) and IL-8/IL10 (P = .03) ratios were decreased in CKD patients. CKD patients with low secretion levels of stimulated saliva expressed decreased levels of TNF-α (P = .04), IL-1β (P = .02), γ-INF (P = .03), IL-6 (P = .003), IL-8 (P = .005), MCP-1 (P = .006), and sICAM-1 (P = .02).
CONCLUSIONS: Salivary cytokines and secretion rates are significantly decreased in CKD patients. Further research is necessary to understand operating mechanisms and clinical implications of the down-regulation of inflammatory markers in saliva.