METHODS: There were 104 participants in the study: 19 healthy volunteers, 23 patients with periodontitis, 28 patients with T1DM, and 34 patients with T1DM and periodontitis. Levels of blood glucose/glycated hemoglobin (International Federation of Clinical Chemistry [IFCC]) were determined by high-performance liquid chromatography. Levels of IL-6, IL-8, and CXCL5 in plasma were determined by enzyme-linked immunosorbent assay (ELISA). In vitro stimulation of OKF6/TERT-2 cells and THP-1 monocytes was performed with combinations of AGE and P. gingivalis LPS. Changes in expression of IL-6, IL-8, and CXCL5 were monitored by ELISA and real-time polymerase chain reaction.
RESULTS: Patients with diabetes and periodontitis had higher plasma levels of IL-8 than patients with periodontitis alone. Plasma levels of IL-8 correlated significantly with IFCC units, clinical probing depth, and attachment loss. AGE and LPS, alone or in combination, stimulated IL-6, IL-8, and CXCL5 expression in both OKF6/TERT-2 cells and THP-1 monocytes.
CONCLUSIONS: Elevated plasma levels of IL-8 potentially contribute to the cross-susceptibility between periodontitis and T1DM. P. gingivalis LPS and AGE in combination caused significantly greater expression of IL-6, IL-8, and CXCL5 from THP-1 monocytes and OKF6/TERT-2 cells than LPS alone.