Detection of local and systemic cytokines in adult periodontitis
The purpose of this study was to compare the pattern of cytokine production in healthy controls and periodontitis patients. Peripheral blood and/or gingival samples were obtained from 24 adult volunteers. Peripheral blood was obtained from the 15 patients undergoing periodontal surgery. Blood also was collected from nine additional periodontally healthy controls. Twenty-five diseased tissue samples and 12 healthy samples were obtained from patients undergoing surgery for moderate to severe periodontitis. In addition, two samples were obtained from periodontally healthy individuals undergoing crown lengthening. Samples were compared in terms of cell surface markers, includingTCR theta-beta, TCR gamma-theta, CD4, CD8, CD16, CD25, CD45, CD56, and a B cell marker (CD20), and the class MHC marker HLA-DR using monoclonal antibodies. Cytokine levels, IL-2, IL-6, IFN-gamma, and IL4, were determined by ELISA. Expression of cytokine mRNA and T cell mRNA in plasma and in gingival tissues was determined by PCR amplification.
The flow cytometry used to determine cell surface markers showed no significant differences between groups in the expression of the T cell markers. However, plasma from patients expressed significantly lower levels of CD16 and CD56 when compared with controls. Plasma levels of Th 1 cytokines (IL-2 and IFN-gamma), the Th 2 cytokine IL-4, and the inflammatory cytokine IL-6 were below the level of detection in both patients and controls. There was no significant difference between healthy controls and patients in the plasma levels of IFN-gamma and IL-10. The mRNA expression of Th 1 cytokines and inflammatory cytokines was not significantly different in the plasma of controls and patients. gamma-theta cells were detected in 13/25 diseased tissues but in none of the healthy tissue samples. The difference in gamma-theta-T cell expression between the groups was statistically significant. IFN-theta mRNA was detected in nearly all of the healthy and diseased tissue samples. However, densitometric analysis of the gels indicated that IFN-theta expression was significantly higher in diseased tissues as compared to healthy tissues. IL-6 mRNA was routinely detected in healthy and diseased tissues, but its expression was significantly higher in diseased tissues when compared with healthy tissues.
In conclusion, surface markers CD16 and CD56 were expressed on significantly fewer peripheral mononuclear cells of patients when compared with control. Further, gamma-theta-T cells were found in half of the diseased tissues, but in none of the healthy tissues of either patients or controls. Finally, significant differences were observed between healthy and inflamed gingival tissues in the cytokine mRNA profile. The increased expression of IFN-theta mRNA in diseased tissues implicates IFN-theta in the pathogenesis of periodontitis. [C.C.]
Prabhu, A., B.S. Michalowicz, and A. Mathur, J Periodont, 67:515, 1996